1/48-scale model of an F-18 aircraft in Flow Visualization Facility (FVF)

NASA Technical Reports Server (NTRS)

1980-01-01

This short movie clip shows a plastic 1/48-scale model of an F-18 aircraft inside the 'Water Tunnel' more formally known as the NASA Dryden Flow Visualization Facility. Water is pumped through the tunnel in the direction of normal airflow over the aircraft; then, colored dyes are pumped through tubes with needle valves. The dyes flow back along the airframe and over the airfoils highlighting their aerodynamic characteristics. The aircraft can also be moved through its pitch axis to observe airflow disruptions while simulating actual flight at high angles of attack. The Water Tunnel at NASA's Dryden Flight Research Center, Edwards, CA, became operational in 1983 when Dryden was a Flight Research Facility under the management of the Ames Research Center in Mountain View, CA. As a medium for visualizing fluid flow, water has played a significant role. Its use dates back to Leonardo da Vinci (1452-1519), the Renaissance Italian engineer, architect, painter, and sculptor. In more recent times, water tunnels have assisted the study of complex flows and flow-field interactions on aircraft shapes that generate strong vortex flows. Flow visualization in water tunnels assists in determining the strength of vortices, their location, and possible methods of controlling them. The design of the Dryden Water Tunnel imitated that of the Northrop Corporation's tunnel in Hawthorne, CA. Called the Flow Visualization Facility, the Dryden tunnel was built to assist researchers in understanding the aerodynamics of aircraft configured in such a way that they create strong vortex flows, particularly at high angles of attack. The tunnel provides results that compare well with data from aircraft in actual flight in another fluid-air. Other uses of the tunnel have included study of how such flight hardware as antennas, probes, pylons, parachutes, and experimental fixtures affect airflow. The facility has also been helpful in finding the best locations for emitting smoke from flight vehicles for flow visualization.

Mushrooms use convectively created airflows to disperse their spores

PubMed Central

Dressaire, Emilie; Yamada, Lisa; Song, Boya; Roper, Marcus

2016-01-01

Thousands of basidiomycete fungal species rely on mushroom spores to spread across landscapes. It has long been thought that spores depend on favorable winds for dispersal—that active control of spore dispersal by the parent fungus is limited to an impulse delivered to the spores to carry them clear of the gill surface. Here we show that evaporative cooling of the air surrounding the pileus creates convective airflows capable of carrying spores at speeds of centimeters per second. Convective cells can transport spores from gaps that may be only 1 cm high and lift spores 10 cm or more into the air. This work reveals how mushrooms tolerate and even benefit from crowding and explains their high water needs. PMID:26929324

Forced-air patient warming blankets disrupt unidirectional airflow.

PubMed

Legg, A J; Hamer, A J

2013-03-01

We have recently shown that waste heat from forced-air warming blankets can increase the temperature and concentration of airborne particles over the surgical site. The mechanism for the increased concentration of particles and their site of origin remained unclear. We therefore attempted to visualise the airflow in theatre over a simulated total knee replacement using neutral-buoyancy helium bubbles. Particles were created using a Rocket PS23 smoke machine positioned below the operating table, a potential area of contamination. The same theatre set-up, warming devices and controls were used as in our previous study. This demonstrated that waste heat from the poorly insulated forced-air warming blanket increased the air temperature on the surgical side of the drape by > 5°C. This created convection currents that rose against the downward unidirectional airflow, causing turbulence over the patient. The convection currents increased the particle concentration 1000-fold (2 174 000 particles/m(3) for forced-air warming vs 1000 particles/m(3) for radiant warming and 2000 particles/m(3) for the control) by drawing potentially contaminated particles from below the operating table into the surgical site. Cite this article: Bone Joint J 2013;95-B:407-10.

Childhood-Onset Asthma in Smokers. Association between CT Measures of Airway Size, Lung Function, and Chronic Airflow Obstruction

PubMed Central

Hardin, Megan E.; Come, Carolyn E.; San José Estépar, Raúl; Ross, James C.; Kurugol, Sila; Okajima, Yuka; Han, MeiLan K.; Kim, Victor; Ramsdell, Joe; Silverman, Edwin K.; Crapo, James D.; Lynch, David A.; Make, Barry; Barr, R. Graham; Hersh, Craig P.; Washko, George R.

2014-01-01

Rationale and Objectives: Asthma is associated with chronic airflow obstruction. Our goal was to assess the association of computed tomographic measures of airway wall volume and lumen volume with the FEV1 and chronic airflow obstruction in smokers with childhood-onset asthma. Methods: We analyzed clinical, lung function, and volumetric computed tomographic airway volume data from 7,266 smokers, including 590 with childhood-onset asthma. Small wall volume and small lumen volume of segmental airways were defined as measures 1 SD below the mean. We assessed the association between small wall volume, small lumen volume, FEV1, and chronic airflow obstruction (post-bronchodilator FEV1/FVC ratio < 0.7) using linear and logistic models. Measurements and Main Results: Compared with subjects without childhood-onset asthma, those with childhood-onset asthma had smaller wall volume and lumen volume (P < 0.0001) of segmental airways. Among subjects with childhood-onset asthma, those with the smallest wall volume and lumen volume had the lowest FEV1 and greatest odds of chronic airflow obstruction. A similar tendency was seen in those without childhood-onset asthma. When comparing these two groups, both small wall volume and small lumen volume were more strongly associated with FEV1 and chronic airflow obstruction among subjects with childhood-asthma in multivariate models. Conclusion: In smokers with childhood-onset asthma, smaller airways are associated with reduced lung function and chronic airflow obstruction. Clinical trial registered with www.clinicaltrials.gov (NCT00608764). PMID:25296268

Childhood-onset asthma in smokers. association between CT measures of airway size, lung function, and chronic airflow obstruction.

PubMed

Diaz, Alejandro A; Hardin, Megan E; Come, Carolyn E; San José Estépar, Raúl; Ross, James C; Kurugol, Sila; Okajima, Yuka; Han, MeiLan K; Kim, Victor; Ramsdell, Joe; Silverman, Edwin K; Crapo, James D; Lynch, David A; Make, Barry; Barr, R Graham; Hersh, Craig P; Washko, George R

2014-11-01

Asthma is associated with chronic airflow obstruction. Our goal was to assess the association of computed tomographic measures of airway wall volume and lumen volume with the FEV1 and chronic airflow obstruction in smokers with childhood-onset asthma. We analyzed clinical, lung function, and volumetric computed tomographic airway volume data from 7,266 smokers, including 590 with childhood-onset asthma. Small wall volume and small lumen volume of segmental airways were defined as measures 1 SD below the mean. We assessed the association between small wall volume, small lumen volume, FEV1, and chronic airflow obstruction (post-bronchodilator FEV1/FVC ratio < 0.7) using linear and logistic models. Compared with subjects without childhood-onset asthma, those with childhood-onset asthma had smaller wall volume and lumen volume (P < 0.0001) of segmental airways. Among subjects with childhood-onset asthma, those with the smallest wall volume and lumen volume had the lowest FEV1 and greatest odds of chronic airflow obstruction. A similar tendency was seen in those without childhood-onset asthma. When comparing these two groups, both small wall volume and small lumen volume were more strongly associated with FEV1 and chronic airflow obstruction among subjects with childhood-asthma in multivariate models. In smokers with childhood-onset asthma, smaller airways are associated with reduced lung function and chronic airflow obstruction. Clinical trial registered with www.clinicaltrials.gov (NCT00608764).

Burning Plastics Investigated in Space for Unique US/Russian Cooperative Project

NASA Technical Reports Server (NTRS)

Friedman, Robert

2000-01-01

It is well known that fires in the low-gravity environment of Earth-orbiting spacecraft are different from fires on Earth. The flames lack the familiar upward plume, which is the result of gravitational buoyancy. These flames, however, are strongly influenced by minor airflow currents. A recent study conducted in low gravity (microgravity) on the Russian orbital station Mir used burning plastic rods mounted in a small chamber with a controllable fan to expose the flame to airflows of different velocities. In this unique project, a Russian scientific agency, the Keldysh Research Center, furnished the apparatus and directed the Mir tests, while the NASA Glenn Research Center at Lewis Field provided the test materials and the project management. Reference testing and calibrations in ground laboratories were conducted jointly by researchers at Keldysh and at the NASA Johnson Space Center's White Sands Test Facility. Multiple samples of three different plastics were burned in the tests: Delrin, a common material for valve bodies; PMMA, a plastic "glass"; and polyethylene, a familiar material for containers and films. Each burned with a unique spherical or egg-shaped flame that spread over the rod. The effect of varying the airflow was dramatic. At the highest airflow attainable in the combustion chamber, nearly 10 cm/sec (a typical ventilation breeze), the flames were bright and strong. As airflow velocity decreased, the flames became shorter but wider. In addition, the flames became less bright, and for PMMA and polyethylene, they showed two colors, a bright part decreasing in volume and a nearly invisible remainder (see the photographs). Finally, at a very low velocity, the flames extinguished. For the plastics tested, this minimum velocity was very low, around 0.3 to 0.5 cm/sec. This finding confirms that at least a slight airflow is required to maintain a flame in microgravity for these types of materials.

Reduced Expiratory Flow Rate among Heavy Smokers Increases Lung Cancer Risk. Results from the National Lung Screening Trial-American College of Radiology Imaging Network Cohort.

PubMed

Hopkins, Raewyn J; Duan, Fenghai; Chiles, Caroline; Greco, Erin M; Gamble, Greg D; Aberle, Denise; Young, Robert P

2017-03-01

Although epidemiological studies consistently show that chronic obstructive pulmonary disease is associated with an increased risk of lung cancer, debate exists as to whether there is a linear relationship between the severity of airflow limitation and lung cancer risk. We examined this in a large, prospective study of older heavy smokers from the American College of Radiology Imaging Network subcohort of the National Lung Screening Trial (ACRIN). Airflow limitation was defined by prebronchodilator spirometry subgrouped according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 1-4. In the National Lung Screening Trial-ACRIN cohort of 18,473 screening participants, 6,436 had airflow limitation (35%) and 12,037 (65%) had no airflow limitation. From these groups, 758 lung cancer cases were prospectively identified. Participants with airflow limitation were stratified according to GOLD groups 1 (n = 1,607), 2 (n = 3,528), 3 (n = 1,083), and 4 (n = 211). Lung cancer incidence at study end (mean follow-up, 6.4 yr) was compared between the GOLD groups and those with no airflow limitation (referent group). Compared with those with no airflow limitation, where lung cancer incidence was 3.78/1,000 person years, incidence rates increased in a simple linear relationship: GOLD 1 (6.27/1,000 person yr); GOLD 2 (7.86/1,000 person yr); GOLD 3 (10.71/1,000 person yr); and GOLD 4 (13.25/1,000 person yr). All relationships were significant versus the reference group at a P value of 0.0001 or less. In a large prospective study of high-risk cigarette smokers, we report a strong linear relationship between increasing severity of airflow limitation and risk of lung cancer.

Patient specific CFD models of nasal airflow: overview of methods and challenges.

PubMed

Kim, Sung Kyun; Na, Yang; Kim, Jee-In; Chung, Seung-Kyu

2013-01-18

Respiratory physiology and pathology are strongly dependent on the airflow inside the nasal cavity. However, the nasal anatomy, which is characterized by complex airway channels and significant individual differences, is difficult to analyze. Thus, commonly adopted diagnostic tools have yielded limited success. Nevertheless, with the rapid advances in computer resources, there have been more elaborate attempts to correlate airflow characteristics in human nasal airways with the symptoms and functions of the nose by computational fluid dynamics study. Furthermore, the computed nasal geometry can be virtually modified to reflect predicted results of the proposed surgical technique. In this article, several computational fluid mechanics (CFD) issues on patient-specific three dimensional (3D) modeling of nasal cavity and clinical applications were reviewed in relation to the cases of deviated nasal septum (decision for surgery), turbinectomy, and maxillary sinus ventilation (simulated- and post-surgery). Clinical relevance of fluid mechanical parameters, such as nasal resistance, flow allocation, wall shear stress, heat/humidity/NO gas distributions, to the symptoms and surgical outcome were discussed. Absolute values of such parameters reported by many research groups were different each other due to individual difference of nasal anatomy, the methodology for 3D modeling and numerical grid, laminar/turbulent flow model in CFD code. But, the correlation of these parameters to symptoms and surgery outcome seems to be obvious in each research group with subject-specific models and its variations (virtual- and post-surgery models). For the more reliable, patient-specific, and objective tools for diagnosis and outcomes of nasal surgery by using CFD, the future challenges will be the standardizations on the methodology for creating 3D airway models and the CFD procedures. Copyright © 2012 Elsevier Ltd. All rights reserved.

Chaotic component obscured by strong periodicity in voice production system

NASA Astrophysics Data System (ADS)

Tao, Chao; Jiang, Jack J.

2008-06-01

The effect of glottal aerodynamics in producing the nonlinear characteristics of voice is investigated by comparing the outputs of the asymmetric composite model and the two-mass model. The two-mass model assumes the glottal airflow to be laminar, nonviscous, and incompressible. In this model, when the asymmetric factor is decreased from 0.65 to 0.35, only 1:1 and 1:2 modes are detectable. However, with the same parameters, four vibratory modes (1:1, 1:2, 2:4, 2:6) are found in the asymmetric composite model using the Navier-Stokes equations to describe the complex aerodynamics in the glottis. Moreover, the amplitude of the waveform is modulated by a small-amplitude noiselike series. The nonlinear detection method reveals that this noiselike modulation is not random, but rather it is deterministic chaos. This result agrees with the phenomenon often seen in voice, in which the voice signal is strongly periodic but modulated by a small-amplitude chaotic component. The only difference between the two-mass model and the composite model is in their descriptions of glottal airflow. Therefore, the complex aerodynamic characteristics of glottal airflow could be important in generating the nonlinear dynamic behavior of voice production, including bifurcation and a small-amplitude chaotic component obscured by strong periodicity.

Chaotic component obscured by strong periodicity in voice production system

PubMed Central

Tao, Chao; Jiang, Jack J.

2010-01-01

The effect of glottal aerodynamics in producing the nonlinear characteristics of voice is investigated by comparing the outputs of the asymmetric composite model and the two-mass model. The two-mass model assumes the glottal airflow to be laminar, nonviscous, and incompressible. In this model, when the asymmetric factor is decreased from 0.65 to 0.35, only 1:1 and 1:2 modes are detectable. However, with the same parameters, four vibratory modes (1:1, 1:2, 2:4, 2:6) are found in the asymmetric composite model using the Navier-Stokes equations to describe the complex aerodynamics in the glottis. Moreover, the amplitude of the waveform is modulated by a small-amplitude noiselike series. The nonlinear detection method reveals that this noiselike modulation is not random, but rather it is deterministic chaos. This result agrees with the phenomenon often seen in voice, in which the voice signal is strongly periodic but modulated by a small-amplitude chaotic component. The only difference between the two-mass model and the composite model is in their descriptions of glottal airflow. Therefore, the complex aerodynamic characteristics of glottal airflow could be important in generating the nonlinear dynamic behavior of voice production, including bifurcation and a small-amplitude chaotic component obscured by strong periodicity. PMID:18643315

Lung sound intensity in patients with emphysema and in normal subjects at standardised airflows.

PubMed Central

Schreur, H J; Sterk, P J; Vanderschoot, J; van Klink, H C; van Vollenhoven, E; Dijkman, J H

1992-01-01

BACKGROUND: A common auscultatory finding in pulmonary emphysema is a reduction of lung sounds. This might be due to a reduction in the generation of sounds due to the accompanying airflow limitation or to poor transmission of sounds due to destruction of parenchyma. Lung sound intensity was investigated in normal and emphysematous subjects in relation to airflow. METHODS: Eight normal men (45-63 years, FEV1 79-126% predicted) and nine men with severe emphysema (50-70 years, FEV1 14-63% predicted) participated in the study. Emphysema was diagnosed according to pulmonary history, results of lung function tests, and radiographic criteria. All subjects underwent phonopneumography during standardised breathing manoeuvres between 0.5 and 2 1 below total lung capacity with inspiratory and expiratory target airflows of 2 and 1 l/s respectively during 50 seconds. The synchronous measurements included airflow at the mouth and lung volume changes, and lung sounds at four locations on the right chest wall. For each microphone airflow dependent power spectra were computed by using fast Fourier transformation. Lung sound intensity was expressed as log power (in dB) at 200 Hz at inspiratory flow rates of 1 and 2 l/s and at an expiratory flow rate of 1 l/s. RESULTS: Lung sound intensity was well repeatable on two separate days, the intraclass correlation coefficient ranging from 0.77 to 0.94 between the four microphones. The intensity was strongly influenced by microphone location and airflow. There was, however, no significant difference in lung sound intensity at any flow rate between the normal and the emphysema group. CONCLUSION: Airflow standardised lung sound intensity does not differ between normal and emphysematous subjects. This suggests that the auscultatory finding of diminished breath sounds during the regular physical examination in patients with emphysema is due predominantly to airflow limitation. Images PMID:1440459

Improved Cattle Hauler

NASA Technical Reports Server (NTRS)

Saltzman, E. J.

1983-01-01

Better aerodynamics and ventilation increases fuel efficiency and decreases shipping losses. Trailer is ventilated and cooled by inlet ports in front of rig and outlet ports in middle and rear. Rounded cab and fairing reduce drag by creating an attached airflow.

Effect of anatomy on human nasal air flow and odorant transport patterns: implications for olfaction.

PubMed

Zhao, Kai; Scherer, Peter W; Hajiloo, Shoreh A; Dalton, Pamela

2004-06-01

Recent studies that have compared CT or MRI images of an individual's nasal anatomy and measures of their olfactory sensitivity have found a correlation between specific anatomical areas and performance on olfactory assessments. Using computational fluid dynamics (CFD) techniques, we have developed a method to quickly (

Airflow-terrain interactions through a mountain gap, with an example of eolian activity beneath an atmospheric hydraulic jump

NASA Astrophysics Data System (ADS)

Gaylord, David R.; Dawson, Paul J.

1987-09-01

The integration of atmospheric soundings from a fully instrumented aircraft with detailed sedimentary and geomorphic analyses of eolian features in the Ferris dune field of south-central Wyoming lends insight into the manner in which topography interacts with airflow to modify eolian activity. Topographically modified airflow results in zones of airflow deceleration, acceleration, and enhanced atmospheric turbulence, all of which influence the surface morphology and sedimentology. Extreme lateral confluence of prevailing airflow produces accelerated, unidirectional winds. These winds correlate with unusually continuous and elongate parabolic dunes that extend into a mountain gap (Windy Gap). Persistently heightened winds produced at the entrance to Windy Gap have resulted in a concentration of active sand dunes that lack slipfaces. Common development of a strongly amplified atmospheric wave analogous to a hydraulic jump in the gap contributes to the formation of a variety of eolian features that mantle the surface of Windy Gap and the Ferris dune field tail. Heightened, unidirectional winds in this zone promote grain-size segregation, the formation of elongated and aligned sand drifts, climbing and falling dunes, elongate scour streaks, and parabolic dunes that have low-angle (<20°) cross-stratification. Deflation of bedrock and loose sediment has been enhanced in the zone of maximum turbulence beneath the hydraulic jump.

Reduced Expiratory Flow Rate among Heavy Smokers Increases Lung Cancer Risk. Results from the National Lung Screening Trial–American College of Radiology Imaging Network Cohort

PubMed Central

Hopkins, Raewyn J.; Duan, Fenghai; Chiles, Caroline; Greco, Erin M.; Gamble, Greg D.; Aberle, Denise

2017-01-01

Rationale: Although epidemiological studies consistently show that chronic obstructive pulmonary disease is associated with an increased risk of lung cancer, debate exists as to whether there is a linear relationship between the severity of airflow limitation and lung cancer risk. Objectives: We examined this in a large, prospective study of older heavy smokers from the American College of Radiology Imaging Network subcohort of the National Lung Screening Trial (ACRIN). Airflow limitation was defined by prebronchodilator spirometry subgrouped according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 1–4. Methods: In the National Lung Screening Trial–ACRIN cohort of 18,473 screening participants, 6,436 had airflow limitation (35%) and 12,037 (65%) had no airflow limitation. From these groups, 758 lung cancer cases were prospectively identified. Participants with airflow limitation were stratified according to GOLD groups 1 (n = 1,607), 2 (n = 3,528), 3 (n = 1,083), and 4 (n = 211). Lung cancer incidence at study end (mean follow-up, 6.4 yr) was compared between the GOLD groups and those with no airflow limitation (referent group). Measurements and Main Results: Compared with those with no airflow limitation, where lung cancer incidence was 3.78/1,000 person years, incidence rates increased in a simple linear relationship: GOLD 1 (6.27/1,000 person yr); GOLD 2 (7.86/1,000 person yr); GOLD 3 (10.71/1,000 person yr); and GOLD 4 (13.25/1,000 person yr). All relationships were significant versus the reference group at a P value of 0.0001 or less. Conclusions: In a large prospective study of high-risk cigarette smokers, we report a strong linear relationship between increasing severity of airflow limitation and risk of lung cancer. PMID:28076701

What can vortices tell us about vocal fold vibration and voice production.

PubMed

Khosla, Sid; Murugappan, Shanmugam; Gutmark, Ephraim

2008-06-01

Much clinical research on laryngeal airflow has assumed that airflow is unidirectional. This review will summarize what additional knowledge can be obtained about vocal fold vibration and voice production by studying rotational motion, or vortices, in laryngeal airflow. Recent work suggests two types of vortices that may strongly contribute to voice quality. The first kind forms just above the vocal folds during glottal closing, and is formed by flow separation in the glottis; these flow separation vortices significantly contribute to rapid closing of the glottis, and hence, to producing loudness and high frequency harmonics in the acoustic spectrum. The second is a group of highly three-dimensional and coherent supraglottal vortices, which can produce sound by interaction with structures in the vocal tract. Present work is also described that suggests that certain laryngeal pathologies, such as asymmetric vocal fold tension, will significantly modify both types of vortices, with adverse impact on sound production: decreased rate of glottal closure, increased broadband noise, and a decreased signal to noise ratio. Recent research supports the hypothesis that glottal airflow contains certain vortical structures that significantly contribute to voice quality.

Estimating subglottal pressure via airflow interruption with auditory masking.

PubMed

Hoffman, Matthew R; Jiang, Jack J

2009-11-01

Current noninvasive measurement of subglottal pressure using airflow interruption often produces inconsistent results due to the elicitation of audio-laryngeal reflexes. Auditory feedback could be considered as a means of ensuring measurement accuracy and precision. The purpose of this study was to determine if auditory masking could be used with the airflow interruption system to improve intrasubject consistency. A prerecorded sample of subject phonation was played on a loop over headphones during the trials with auditory masking. This provided subjects with a target pitch and blocked out distracting ambient noise created by the airflow interrupter. Subglottal pressure was noninvasively measured using the airflow interruption system. Thirty subjects, divided into two equal groups, performed 10 trials without auditory masking and 10 trials with auditory masking. Group one performed the normal trials first, followed by the trials with auditory masking. Group two performed the auditory masking trials first, followed by the normal trials. Intrasubject consistency was improved by adding auditory masking, resulting in a decrease in average intrasubject standard deviation from 0.93+/-0.51 to 0.47+/-0.22 cm H(2)O (P < 0.001). Auditory masking can be used effectively to combat audio-laryngeal reflexes and aid subjects in maintaining constant glottal configuration and frequency, thereby increasing intrasubject consistency when measuring subglottal pressure. By considering auditory feedback, a more reliable method of measurement was developed. This method could be used by clinicians, as reliable, immediately available values of subglottal pressure are useful in evaluating laryngeal health and monitoring treatment progress.

Human convective boundary layer and its interaction with room ventilation flow.

PubMed

Licina, D; Melikov, A; Sekhar, C; Tham, K W

2015-02-01

This study investigates the interaction between the human convective boundary layer (CBL) and uniform airflow with different velocity and from different directions. Human body is resembled by a thermal manikin with complex body shape and surface temperature distribution as the skin temperature of an average person. Particle image velocimetry (PIV) and pseudocolor visualization (PCV) are applied to identify the flow around the manikin's body. The findings show that the direction and magnitude of the surrounding airflows considerably influence the airflow distribution around the human body. Downward flow with velocity of 0.175 m/s does not influence the convective flow in the breathing zone, while flow at 0.30 m/s collides with the CBL at the nose level reducing the peak velocity from 0.185 to 0.10 m/s. Transverse horizontal flow disturbs the CBL at the breathing zone even at 0.175 m/s. A sitting manikin exposed to airflow from below with velocity of 0.30 and 0.425 m/s assisting the CBL reduces the peak velocity in the breathing zone and changes the flow pattern around the body, compared to the assisting flow of 0.175 m/s or quiescent conditions. In this case, the airflow interaction is strongly affected by the presence of the chair. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

COMIS -- an international multizone air-flow and contaminant transport model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feustel, H.E.

1998-08-01

A number of interzonal models have been developed to calculate air flows and pollutant transport mechanisms in both single and multizone buildings. A recent development in multizone air-flow modeling, the COMIS model, has a number of capabilities that go beyond previous models, much as COMIS can be used as either a stand-alone air-flow model with input and output features or as an infiltration module for thermal building simulation programs. COMIS was designed during a 12 month workshop at Lawrence Berkeley National Laboratory (LBNL) in 1988-89. In 1990, the Executive Committee of the International Energy Agency`s Energy Conservation in Buildings andmore » Community Systems program created a working group on multizone air-flow modeling, which continued work on COMIS. The group`s objectives were to study physical phenomena causing air flow and pollutant (e.g., moisture) transport in multizone buildings, develop numerical modules to be integrated in the previously designed multizone air flow modeling system, and evaluate the computer code. The working group supported by nine nations, officially finished in late 1997 with the release of IISiBat/COMIS 3.0, which contains the documented simulation program COMIS, the user interface IISiBat, and reports describing the evaluation exercise.« less

Structure of the airflow above surface waves

NASA Astrophysics Data System (ADS)

Buckley, Marc; Veron, Fabrice

2016-04-01

Weather, climate and upper ocean patterns are controlled by the exchanges of momentum, heat, mass, and energy across the ocean surface. These fluxes are, in turn, influenced by the small-scale physics at the wavy air-sea interface. We present laboratory measurements of the fine-scale airflow structure above waves, achieved in over 15 different wind-wave conditions, with wave ages Cp/u* ranging from 1.4 to 66.7 (where Cp is the peak phase speed of the waves, and u* the air friction velocity). The experiments were performed in the large (42-m long) wind-wave-current tank at University of Delaware's Air-Sea Interaction laboratory (USA). A combined Particle Image Velocimetry and Laser Induced Fluorescence system was specifically developed for this study, and provided two-dimensional airflow velocity measurement as low as 100 um above the air-water interface. Starting at very low wind speeds (U10~2m/s), we directly observe coherent turbulent structures within the buffer and logarithmic layers of the airflow above the air-water interface, whereby low horizontal velocity air is ejected away from the surface, and higher velocity fluid is swept downward. Wave phase coherent quadrant analysis shows that such turbulent momentum flux events are wave-phase dependent. Airflow separation events are directly observed over young wind waves (Cp/u*<3.7) and counted using measured vorticity and surface viscous stress criteria. Detached high spanwise vorticity layers cause intense wave-coherent turbulence downwind of wave crests, as shown by wave-phase averaging of turbulent momentum fluxes. Mean wave-coherent airflow motions and fluxes also show strong phase-locked patterns, including a sheltering effect, upwind of wave crests over old mechanically generated swells (Cp/u*=31.7), and downwind of crests over young wind waves (Cp/u*=3.7). Over slightly older wind waves (Cp/u* = 6.5), the measured wave-induced airflow perturbations are qualitatively consistent with linear critical layer theory.

Alterations of the arginine metabolome in asthma.

PubMed

Lara, Abigail; Khatri, Sumita B; Wang, Zeneng; Comhair, Suzy A A; Xu, Weiling; Dweik, Raed A; Bodine, Melanie; Levison, Bruce S; Hammel, Jeffrey; Bleecker, Eugene; Busse, William; Calhoun, William J; Castro, Mario; Chung, Kian Fan; Curran-Everett, Douglas; Gaston, Benjamin; Israel, Elliot; Jarjour, Nizar; Moore, Wendy; Peters, Stephen P; Teague, W Gerald; Wenzel, Sally; Hazen, Stanley L; Erzurum, Serpil C

2008-10-01

As the sole nitrogen donor in nitric oxide (NO) synthesis and key intermediate in the urea cycle, arginine and its metabolic pathways are integrally linked to cellular respiration, metabolism, and inflammation. We hypothesized that arginine (Arg) bioavailability would be associated with airflow abnormalities and inflammation in subjects with asthma, and would be informative for asthma severity. Arg bioavailability was assessed in subjects with severe and nonsevere asthma and healthy control subjects by determination of plasma Arg relative to its metabolic products, ornithine and citrulline, and relative to methylarginine inhibitors of NO synthases, and by serum arginase activity. Inflammatory parameters, including fraction of exhaled NO (Fe(NO)), IgE, skin test positivity to allergens, bronchoalveolar lavage, and blood eosinophils, were also evaluated. Subjects with asthma had greater Arg bioavailability, but also increased Arg catabolism compared with healthy control subjects, as evidenced by higher levels of Fe(NO) and serum arginase activity. However, Arg bioavailability was positively associated with Fe(NO) only in healthy control subjects; Arg bioavailability was unrelated to Fe(NO) or other inflammatory parameters in severe or nonsevere asthma. Inflammatory parameters were related to airflow obstruction and reactivity in nonsevere asthma, but not in severe asthma. Conversely, Arg bioavailability was related to airflow obstruction in severe asthma, but not in nonsevere asthma. Modeling confirmed that measures of Arg bioavailabilty predict airflow obstruction only in severe asthma. Unlike Fe(NO), Arg bioavailability is not a surrogate measure of inflammation; however, Arg bioavailability is strongly associated with airflow abnormalities in severe asthma.

Air Force Laboratory’s 2005 Technology Milestones

DTIC Science & Technology

2006-01-01

Computational materials science methods can benefit the design and property prediction of complex real-world materials. With these models , scientists and...Warfighter Page Air High - Frequency Acoustic System...800) 203-6451 High - Frequency Acoustic System Payoff Scientists created the High - Frequency Acoustic Suppression Technology (HiFAST) airflow control

A trajectory design method via target practice for air-breathing hypersonic vehicle

NASA Astrophysics Data System (ADS)

Kong, Xue; Yang, Ming; Ning, Guodong; Wang, Songyan; Chao, Tao

2017-11-01

There are strong coupling interactions between aerodynamics and scramjet, this kind of aircraft also has multiple restrictions, such as the range and difference of dynamic pressure, airflow, and fuel. On the one hand, we need balance the requirement between maneuverability of vehicle and stabilization of scramjet. On the other hand, we need harmonize the change of altitude and the velocity. By describing aircraft's index system of climbing capability, acceleration capability, the coupling degree in aerospace, this paper further propose a rapid design method which based on target practice. This method aimed for reducing the coupling degree, it depresses the coupling between aircraft and engine in navigation phase, satisfy multiple restriction conditions to leave some control buffer and create good condition for control implementation. According to the simulation, this method could be used for multiple typical fly commissions such as climbing, acceleration or both.

Impact vaporization: Late time phenomena from experiments

NASA Technical Reports Server (NTRS)

Schultz, P. H.; Gault, D. E.

1987-01-01

While simple airflow produced by the outward movement of the ejecta curtain can be scaled to large dimensions, the interaction between an impact-vaporized component and the ejecta curtain is more complicated. The goal of these experiments was to examine such interaction in a real system involving crater growth, ejection of material, two phased mixtures of gas and dust, and strong pressure gradients. The results will be complemented by theoretical studies at laboratory scales in order to separate the various parameters for planetary scale processes. These experiments prompt, however, the following conclusions that may have relevance at broader scales. First, under near vacuum or low atmospheric pressures, an expanding vapor cloud scours the surrounding surface in advance of arriving ejecta. Second, the effect of early-time vaporization is relatively unimportant at late-times. Third, the overpressure created within the crater cavity by significant vaporization results in increased cratering efficiency and larger aspect ratios.

Creation of an idealized nasopharynx geometry for accurate computational fluid dynamics simulations of nasal airflow in patient-specific models lacking the nasopharynx anatomy

PubMed Central

Borojeni, Azadeh A.T.; Frank-Ito, Dennis O.; Kimbell, Julia S.; Rhee, John S.; Garcia, Guilherme J. M.

2016-01-01

Virtual surgery planning based on computational fluid dynamics (CFD) simulations has the potential to improve surgical outcomes for nasal airway obstruction (NAO) patients, but the benefits of virtual surgery planning must outweigh the risks of radiation exposure. Cone beam computed tomography (CBCT) scans represent an attractive imaging modality for virtual surgery planning due to lower costs and lower radiation exposures compared with conventional CT scans. However, to minimize the radiation exposure, the CBCT sinusitis protocol sometimes images only the nasal cavity, excluding the nasopharynx. The goal of this study was to develop an idealized nasopharynx geometry for accurate representation of outlet boundary conditions when the nasopharynx geometry is unavailable. Anatomically-accurate models of the nasopharynx created from thirty CT scans were intersected with planes rotated at different angles to obtain an average geometry. Cross sections of the idealized nasopharynx were approximated as ellipses with cross-sectional areas and aspect ratios equal to the average in the actual patient-specific models. CFD simulations were performed to investigate whether nasal airflow patterns were affected when the CT-based nasopharynx was replaced by the idealized nasopharynx in 10 NAO patients. Despite the simple form of the idealized geometry, all biophysical variables (nasal resistance, airflow rate, and heat fluxes) were very similar in the idealized vs. patient-specific models. The results confirmed the expectation that the nasopharynx geometry has a minimal effect in the nasal airflow patterns during inspiration. The idealized nasopharynx geometry will be useful in future CFD studies of nasal airflow based on medical images that exclude the nasopharynx. PMID:27525807

CT-derived Biomechanical Metrics Improve Agreement Between Spirometry and Emphysema

PubMed Central

Bhatt, Surya P.; Bodduluri, Sandeep; Newell, John D.; Hoffman, Eric A.; Sieren, Jessica C.; Han, Meilan K.; Dransfield, Mark T.; Reinhardt, Joseph M.

2016-01-01

Rationale and Objectives Many COPD patients have marked discordance between FEV1 and degree of emphysema on CT. Biomechanical differences between these patients have not been studied. We aimed to identify reasons for the discordance between CT and spirometry in some patients with COPD. Materials and Methods Subjects with GOLD stage I–IV from a large multicenter study (COPDGene) were arranged by percentiles of %predicted FEV1 and emphysema on CT. Three categories were created using differences in percentiles: Catspir with predominant airflow obstruction/minimal emphysema, CatCT with predominant emphysema/minimal airflow obstruction, and Catmatched with matched FEV1 and emphysema. Image registration was used to derive Jacobian determinants, a measure of lung elasticity, anisotropy and strain tensors, to assess biomechanical differences between groups. Regression models were created with the above categories as outcome variable, adjusting for demographics, scanner type, quantitative CT-derived emphysema, gas trapping, and airway thickness (Model 1), and after adding biomechanical CT metrics (Model 2). Results Jacobian determinants, anisotropy and strain tensors were strongly associated with FEV1. With Catmatched as control, Model 2 predicted Catspir and CatCT better than Model 1 (Akaike Information Criterion, AIC 255.8 vs. 320.8). In addition to demographics, the strongest independent predictors of FEV1 were Jacobian mean (β= 1.60,95%CI = 1.16 to 1.98; p<0.001), coefficient of variation (CV) of Jacobian (β= 1.45,95%CI = 0.86 to 2.03; p<0.001) and CV strain (β= 1.82,95%CI = 0.68 to 2.95; p = 0.001). CVs of Jacobian and strain are both potential markers of biomechanical lung heterogeneity. Conclusions CT-derived measures of lung mechanics improve the link between quantitative CT and spirometry, offering the potential for new insights into the linkage between regional parenchymal destruction and global decrement in lung function in COPD patients. PMID:27055745

Efficiency of an air curtain as an anti-insect barrier: the honey bee as a model insect.

PubMed

Kairo, Guillaume; Pioz, Maryline; Tchamitchian, Sylvie; Pelissier, Michel; Brunet, Jean-Luc; Belzunces, Luc P

2018-05-28

Vector-borne diseases are of high concern for human, animal and plant health. In humans, such diseases are often transmitted by flying insects. Flying insects stop their flight when their kinetic energy cannot compensate for the wind speed. Here, the efficiency of an air curtain in preventing insects from entering a building was studied using the honey bee as a model. Bees were trained to visit a food source placed in a building. The air curtain was tested with strongly motivated bees, when the visiting activity was very high. Airflow velocity was modulated by setting an air curtain device at different voltages. At the nominal voltage, the anti-insect efficiency was 99.9 ± 0.2% compared with both the number of bees at a given time in the absence of the air curtain and the number of bees before the activation of the air curtain. The efficiency decreased as the airflow velocity decreased. The results show that an air curtain operating at an airflow velocity of 7.5 m/sec may prevent a strong flyer with high kinetic energy, such as the honey bee, from entering a building. Thus, air curtains offer an alternative approach for combating vector-borne diseases. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Clinical relevance of fixed ratio vs lower limit of normal of FEV1/FVC in COPD: patient-reported outcomes from the CanCOLD cohort.

PubMed

van Dijk, Wouter; Tan, Wan; Li, Pei; Guo, Best; Li, Summer; Benedetti, Andrea; Bourbeau, Jean

2015-01-01

The way in which spirometry is interpreted can lead to misdiagnosis of chronic obstructive pulmonary disease (COPD) resulting in inappropriate treatment. We compared the clinical relevance of 2 criteria for defining a low ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC): the fixed ratio and the lower limit of normal. We analyzed data from the cross-sectional phase of the population-based Canadian Cohort of Obstructive Lung Disease (CanCOLD) study. We determined associations of the spirometric criteria for airflow limitation with patient-reported adverse outcomes, including respiratory symptoms, disability, health status, exacerbations, and cardiovascular disease. Sensitivity analyses were used to explore the impact of age and severity of airflow limitation on these associations. We analyzed data from 4,882 patients aged 40 years and older. The prevalence of airflow limitation was 17% by fixed ratio and 11% by lower limit of normal. Patients classified as having airflow limitation by fixed ratio only had generally small, nonsignificant increases in the odds of adverse outcomes. Patients having airflow limitation based on both fixed ratio and lower limit of normal had larger, significant increases in odds. But strongest associations were seen for patients who had airflow limitation by both fixed ratio and lower limit of normal and also had a low FEV1, defined as one less than 80% of the predicted value. Our results suggest that use of the fixed ratio alone may lead to misdiagnosis of COPD. A diagnosis established by both a low FEV1/FVC (according to fixed ratio and/or lower limit of normal) and a low FEV1 is strongly associated with clinical outcomes. Guidelines should be reconsidered to require both spirometry abnormalities so as to reduce overdiagnosis of COPD. © 2015 Annals of Family Medicine, Inc.

Nonlinear piezoelectric devices for broadband air-flow energy harvesting

NASA Astrophysics Data System (ADS)

Bai, Y.; Havránek, Z.; Tofel, P.; Meggs, C.; Hughes, H.; Button, T. W.

2015-11-01

This paper presents preliminary work on an investigation of a nonlinear air-flow energy harvester integrating magnets and a piezoelectric cantilever array. Two individual piezoelectric cantilevers with the structure of free-standing multi-layer thick-films have been fabricated and assembled with a free-spinning fan. The cantilevers were attached with different tip masses thereby achieving separated resonant frequencies. Also, permanent magnets were fixed onto the blades of the fan as well as the tips of the cantilevers, in order to create nonlinear coupling and transfer fluidic movement into mechanical oscillation. The device has been tested in a wind tunnel. Bifurcations in the spectra of the blade rotation speed of the fan as a function of output voltage have been observed, and a bandwidth (blade rotation speed range) widening effect has been achieved.

Human-Mediated Dispersal of Seeds by the Airflow of Vehicles

PubMed Central

von der Lippe, Moritz; Bullock, James M.; Kowarik, Ingo; Knopp, Tatjana; Wichmann, Matthias

2013-01-01

Human-mediated dispersal is known as an important driver of long-distance dispersal for plants but underlying mechanisms have rarely been assessed. Road corridors function as routes of secondary dispersal for many plant species but the extent to which vehicles support this process remains unclear. In this paper we quantify dispersal distances and seed deposition of plant species moved over the ground by the slipstream of passing cars. We exposed marked seeds of four species on a section of road and drove a car along the road at a speed of 48 km/h. By tracking seeds we quantified movement parallel as well as lateral to the road, resulting dispersal kernels, and the effect of repeated vehicle passes. Median distances travelled by seeds along the road were about eight meters for species with wind dispersal morphologies and one meter for species without such adaptations. Airflow created by the car lifted seeds and resulted in longitudinal dispersal. Single seeds reached our maximum measuring distance of 45 m and for some species exceeded distances under primary dispersal. Mathematical models were fit to dispersal kernels. The incremental effect of passing vehicles on longitudinal dispersal decreased with increasing number of passes as seeds accumulated at road verges. We conclude that dispersal by vehicle airflow facilitates seed movement along roads and accumulation of seeds in roadside habitats. Dispersal by vehicle airflow can aid the spread of plant species and thus has wide implications for roadside ecology, invasion biology and nature conservation. PMID:23320077

Investigation of induced recirculation during planned ventilation system maintenance

PubMed Central

Pritchard, C.J.; Scott, D.F.; Noll, J.D.; Voss, B.; Leonis, D.

2015-01-01

The Office of Mine Safety and Health Research (OMSHR) investigated ways to increase mine airflow to underground metal/nonmetal (M/NM) mine working areas to improve miners’ health and safety. One of those areas is controlled recirculation. Because the quantity of mine air often cannot be increased, reusing part of the ventilating air can be an effective alternative, if implemented properly, until the capacity of the present system is improved. The additional airflow can be used to provide effective dilution of contaminants and higher flow velocities in the underground mine environment. Most applications of controlled recirculation involve taking a portion of the return air and passing it back into the intake to increase the air volume delivered to the desired work areas. OMSHR investigated a Nevada gold mine where shaft rehabilitation was in progress and one of the two main fans was shut down to allow reduced air velocity for safe shaft work. Underground booster fan operating pressures were kept constant to maintain airflow to work areas, inducing controlled recirculation in one work zone. Investigation into system behavior and the effects of recirculation on the working area during times of reduced primary ventilation system airflow would provide additional information on implementation of controlled recirculation into the system and how these events affect M/NM ventilation systems. The National Institute for Occupational Safety and Health monitored the ventilation district when both main fans were operating and another scenario with one of the units turned off for maintenance. Airflow and contaminants were measured to determine the exposure effects of induced recirculation on miner health. Surveys showed that 19% controlled recirculation created no change in the overall district airflow distribution and a small reduction in district fresh air intake. Total dust levels increased only modestly and respirable dust levels were also low. Diesel particulate matter (DPM) levels showed a high increase in district intake mass flow, but minor increases in exposure levels related to the recirculation percentage. Utilization of DPM mass flow rates allows input into ventilation modeling programs to better understand and plan for ventilation changes and district recirculation effects on miners’ health. PMID:26190862

Electronically steerable ultrasound-driven long narrow air stream

NASA Astrophysics Data System (ADS)

Hasegawa, Keisuke; Qiu, Liwei; Noda, Akihito; Inoue, Seki; Shinoda, Hiroyuki

2017-08-01

Acoustic streaming, which is the unidirectional movement of a medium driven by its internal intense acoustic vibrations, has been known for more than a century. Despite the long history of research, there have been no scientific reports on the creation of long stretching steerable airflows in an open space, generated by ultrasound. Here, we demonstrated the creation of a narrow, straight flow in air to a distance of 400 mm from an ultrasound phased array emitting a Bessel beam. We also demonstrated that the direction of the flow could be controlled by appropriately tuning the wavefronts of the emission from the phased array. Unlike conventional airflows such as those generated by jets or fans, which decelerate and spread out as they travel farther, the flow that we created proceeded while being accelerated by the kinetic energy supplied from the ultrasound beam and keeping the diameter as small as the wavelength. A flow of 3 m/s with a 10 mm diameter extended for several hundreds of millimeters in a room that was large enough to be regarded as an open-boundary environment. These properties of the generated flow will enable fine and rapid control of three-dimensional airflow distributions.

Validation of polyvinylidene fluoride nasal sensor to assess nasal obstruction in comparison with subjective technique.

PubMed

Roopa Manjunatha, G; Mahapatra, D Roy; Prakash, Surya; Rajanna, K

2015-01-01

The aim of this study is to validate the applicability of the PolyVinyliDene Fluoride (PVDF) nasal sensor to assess the nasal airflow, in healthy subjects and patients with nasal obstruction and to correlate the results with the score of Visual Analogue Scale (VAS). PVDF nasal sensor and VAS measurements were carried out in 50 subjects (25-healthy subjects and 25 patients). The VAS score of nasal obstruction and peak-to-peak amplitude (Vp-p) of nasal cycle measured by PVDF nasal sensors were analyzed for right nostril (RN) and left nostril (LN) in both the groups. Spearman's rho correlation was calculated. The relationship between PVDF nasal sensor measurements and severity of nasal obstruction (VAS score) were assessed by ANOVA. In healthy group, the measurement of nasal airflow by PVDF nasal sensor for RN and LN were found to be 51.14±5.87% and 48.85±5.87%, respectively. In patient group, PVDF nasal sensor indicated lesser nasal airflow in the blocked nostrils (RN: 23.33±10.54% and LN: 32.24±11.54%). Moderate correlation was observed in healthy group (r=-0.710, p<0.001 for RN and r=-0.651, p<0.001 for LN), and moderate to strong correlation in patient group (r=-0.751, p<0.01 for RN and r=-0.885, p<0.0001 for LN). PVDF nasal sensor method is a newly developed technique for measuring the nasal airflow. Moderate to strong correlation was observed between PVDF nasal sensor data and VAS scores for nasal obstruction. In our present study, PVDF nasal sensor technique successfully differentiated between healthy subjects and patients with nasal obstruction. Additionally, it can also assess severity of nasal obstruction in comparison with VAS. Thus, we propose that the PVDF nasal sensor technique could be used as a new diagnostic method to evaluate nasal obstruction in routine clinical practice. Copyright © 2015 Elsevier Inc. All rights reserved.

Study of connected system of automatic control of load and operation efficiency of a steam boiler with extremal controller on a simulation model

NASA Astrophysics Data System (ADS)

Sabanin, V. R.; Starostin, A. A.; Repin, A. I.; Popov, A. I.

2017-02-01

The problems of operation effectiveness increase of steam boilers are considered. To maintain the optimum fuel combustion modes, it is proposed to use an extremal controller (EC) determining the value of airflow rate, at which the boiler generating the desired amount of heat will consume a minimum amount of fuel. EC sets the determined value of airflow rate to airflow rate controller (ARC). The test results of numerical simulation dynamic nonlinear model of steam boiler with the connected system of automatic control of load and combustion efficiency using EC are presented. The model is created in the Simulink modeling package of MATLAB software and can be used to optimize the combustion modes. Based on the modeling results, the conclusion was drawn about the possibility in principle of simultaneously boiler load control and optimizing by EC the combustion modes when changing the fuel combustion heat and the boiler characteristics and its operating mode. It is shown that it is possible to automatically control the operation efficiency of steam boilers when using EC without applying the standard flue gas analyzers. The article considers the numerical simulation dynamic model of steam boiler with the schemes of control of fuel consumption and airflow rate, the steam pressure and EC; the purpose of using EC in the scheme with linear controllers and the requirements to the quality of its operation; the results of operation of boiler control schemes without EC with estimation of influence of roughness of thermal mode maps on the nature of static and dynamic connection of the control units of fuel consumption and airflow rate; the phase trajectories and the diagrams of transient processes occurring in the control scheme with EC with stepped changing the fuel quality and boiler characteristics; analysis of modeling results and prospects for using EC in the control schemes of boilers.

Validation of cross-contamination control in biological safety cabinet for biotech/pharmaceutical manufacturing process.

PubMed

Hu, Shih-Cheng; Shiue, Angus; Tu, Jin-Xin; Liu, Han-Yang; Chiu, Rong-Ben

2015-12-01

For class II, type A2 biological safety cabinets (BSC), NSF/ANSI Standard 49 should be conformed in cabinet airflow velocity derivation, particle contamination, and aerodynamic flow properties. However, there exists a potential problem. It has been built that the cabinet air flow stabilize is influenced by the quantity of downflow of air and the height above the cabinet exhaust opening. Three air downflow quantities were compared as an operating apparatus was placed from 20 to 40 cm above the bench of the cabinet. The results show that the BSC air downflow velocity is a function of increased sampling height, displaying that containment is improvingly permitted over product protection as the sampling height decreases. This study investigated the concentration gradient of particles at various heights and downflow air quantity from the bench of the BSC. Experiment results indicate that performance near the bench was better than in the rest of the BSC. In terms of height, the best cleanliness was measured at a height of 10 cm over the bench; it reduced actually with add in height. The empirical curves accommodate, founded on the concentration gradient of particle created was elaborated for evaluating the particle concentration at different heights and downflow air quantity from the source of the bench of the BSC. The particle image velocimetry system applied for BSC airflow research to fix amount of airflow patterns and air distribution measurement and results of measurements show how obstructions can greatly influence the airflow and contaminant transportation in a BSC.

Effects of Forced Air Warming on Airflow around the Operating Table.

PubMed

Shirozu, Kazuhiro; Kai, Tetsuya; Setoguchi, Hidekazu; Ayagaki, Nobuyasu; Hoka, Sumio

2018-01-01

Forced air warming systems are used to maintain body temperature during surgery. Benefits of forced air warming have been established, but the possibility that it may disturb the operating room environment and contribute to surgical site contamination is debated. The direction and speed of forced air warming airflow and the influence of laminar airflow in the operating room have not been reported. In one institutional operating room, we examined changes in airflow speed and direction from a lower-body forced air warming device with sterile drapes mimicking abdominal surgery or total knee arthroplasty, and effects of laminar airflow, using a three-dimensional ultrasonic anemometer. Airflow from forced air warming and effects of laminar airflow were visualized using special smoke and laser light. Forced air warming caused upward airflow (39 cm/s) in the patient head area and a unidirectional convection flow (9 to 14 cm/s) along the ceiling from head to foot. No convection flows were observed around the sides of the operating table. Downward laminar airflow of approximately 40 cm/s counteracted the upward airflow caused by forced air warming and formed downward airflow at 36 to 45 cm/s. Downward airflows (34 to 56 cm/s) flowing diagonally away from the operating table were detected at operating table height in both sides. Airflow caused by forced air warming is well counteracted by downward laminar airflow from the ceiling. Thus it would be less likely to cause surgical field contamination in the presence of sufficient laminar airflow.

Change in airflow among patients with asthma discussing relationship problems with their partners.

PubMed

Schmaling, Karen B; Afari, Niloofar; Hops, Hyman; Barnhart, Scott; Buchwald, Dedra

2009-09-01

This study examined the covariation of negative emotions with airflow among 48 persons with asthma and their partners as they discussed relationship problems. Measures included self-reported questionnaires, airflow and behavior coded from videotaped discussions. Significantly increased self-reported hostility and statistically but not clinically significant declines in airflow were found post- versus pre-discussion. Self-reported responses to asthma symptoms of more anger and less loneliness predicted lower post-discussion airflow after accounting for pre-discussion airflow. The use of effort-independent measures of airflow and autonomic nervous system monitoring may inform future research regarding the physiological mechanisms through which mood and behavior affect airflow.

Traffic in the operating room: a review of factors influencing air flow and surgical wound contamination.

PubMed

Pokrywka, Marian; Byers, Karin

2013-06-01

Surgical wound contamination leading to surgical site infection can result from disruption of the intended airflow in the operating room (OR). When personnel enter and exit the OR, or create unnecessary movement and traffic during the procedure, the intended airflow in the vicinity of the open wound becomes disrupted and does not adequately remove airborne contaminants from the sterile field. An increase in the bacterial counts of airborne microorganisms is noted during increased activity levels within the OR. Researchers have studied OR traffic and door openings as a determinant of air contamination. During a surgical procedure the door to the operating room may be open as long as 20 minutes out of each surgical hour during critical procedures involving implants. Interventions into limiting excessive movement and traffic in the OR may lead to reductions in surgical site infections in select populations.

Drive Fan for the Icing Research Tunnel

NASA Image and Video Library

1944-11-21

View of the drive fan for the Icing Research Tunnel at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory in Cleveland, Ohio. The tunnel was built in the early 1940s to study the formation of ice on aircraft surfaces and methods of preventing or eradicating that ice. Ice buildup adds extra weight, effects aerodynamics, and sometimes blocks airflow through engines. The original 4100-horsepower induction motor was coupled directly to the 24-foot-diameter fan. The 12 wooden fan blades were protected on their leading edge by a neoprene boot. The system could create air speeds up to 300 miles per hour through the tunnel’s 6- by 9-foot test section. The large tail faring extending from the center of the fan is used to guide the airflow down the tunnel in a uniform way. A new 5000-horsepower motor was installed in 1987, and the original fan blades were replaced in 1993.

Regional peak mucosal cooling predicts the perception of nasal patency.

PubMed

Zhao, Kai; Jiang, Jianbo; Blacker, Kara; Lyman, Brian; Dalton, Pamela; Cowart, Beverly J; Pribitkin, Edmund A

2014-03-01

Nasal obstruction is the principal symptom that drives patients with rhinosinus disease to seek medical treatment. However, patient perception of obstruction often bears little relationship to actual measured physical obstruction of airflow. This lack of an objective clinical tool hinders effective diagnosis and treatment. Previous work has suggested that the perception of nasal patency may involve nasal trigeminal activation by cool inspiratory airflow; we attempt to derive clinically relevant variables following this phenomenon. Prospective healthy cohort. Twenty-two healthy subjects rated unilateral nasal patency in controlled room air using a visual analog scale, followed by rhinomanometry, acoustic rhinometry, and butanol lateralization thresholds (BLTs). Each subject then immediately underwent a computed tomography scan, enabling the construction of a real-time computational fluid dynamics (CFD) nasal airway model, which was used to simulate nasal mucosa heat loss during steady resting breathing. Among all measured and computed variables, only CFD-simulated peak heat loss posterior to the nasal vestibule significantly correlated with patency ratings (r = -0.46, P < .01). Linear discriminant analysis predicted patency categories with 89% success rate, with BLT and rhinomanometric nasal resistance being two additional significant variables. As validation, CFD simulated nasal resistance significantly correlated with rhinomanometrically measured resistance (r = 0.41, P < .01). These results reveal that our noses are sensing patency via a mechanism involving localized peak nasal mucosal cooling. The analysis provides a strong rationale for combining the individualized CFD with other objective and neurologic measures to create a novel clinical tool to diagnose nasal obstruction and to predict and evaluate treatment outcomes. © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

Low Frequency Noise Contamination in Fan Model Testing

NASA Technical Reports Server (NTRS)

Brown, Clifford A.; Schifer, Nicholas A.

2008-01-01

Aircraft engine noise research and development depends on the ability to study and predict the noise created by each engine component in isolation. The presence of a downstream pylon for a model fan test, however, may result in noise contamination through pylon interactions with the free stream and model exhaust airflows. Additionally, there is the problem of separating the fan and jet noise components generated by the model fan. A methodology was therefore developed to improve the data quality for the 9 15 Low Speed Wind Tunnel (LSWT) at the NASA Glenn Research Center that identifies three noise sources: fan noise, jet noise, and rig noise. The jet noise and rig noise were then measured by mounting a scale model of the 9 15 LSWT model fan installation in a jet rig to simulate everything except the rotating machinery and in duct components of fan noise. The data showed that the spectra measured in the LSWT has a strong rig noise component at frequencies as high as 3 kHz depending on the fan and airflow fan exit velocity. The jet noise was determined to be significantly lower than the rig noise (i.e., noise generated by flow interaction with the downstream support pylon). A mathematical model for the rig noise was then developed using a multi-dimensional least squares fit to the rig noise data. This allows the rig noise to be subtracted or removed, depending on the amplitude of the rig noise relative to the fan noise, at any given frequency, observer angle, or nozzle pressure ratio. The impact of isolating the fan noise with this method on spectra, overall power level (OAPWL), and Effective Perceived Noise Level (EPNL) is studied.

Lung Function Abnormalities in Smokers with Ischemic Heart Disease.

PubMed

Franssen, Frits M E; Soriano, Joan B; Roche, Nicolas; Bloomfield, Paul H; Brusselle, Guy; Fabbri, Leonardo M; García-Rio, Francisco; Kearney, Mark T; Kwon, Namhee; Lundbäck, Bo; Rabe, Klaus F; Raillard, Alice; Muellerova, Hana; Cockcroft, John R

2016-09-01

The aim of the ALICE (Airflow Limitation in Cardiac Diseases in Europe) study was to investigate the prevalence of airflow limitation in patients with ischemic heart disease and the effects on quality of life, healthcare use, and future health risk. To examine prebronchodilator and post-bronchodilator spirometry in outpatients aged greater than or equal to 40 years with clinically documented ischemic heart disease who were current or former smokers. This multicenter, cross-sectional study was conducted in 15 cardiovascular outpatient clinics in nine European countries. Airflow limitation was defined as post-bronchodilator FEV1/FVC less than 0.70. Among the 3,103 patients with ischemic heart disease who were recruited, lung function was defined for 2,730 patients. Airflow limitation was observed in 30.5% of patients with ischemic heart disease: 11.3% had mild airflow limitation, 15.8% moderate airflow limitation, 3.3% severe airflow limitation, and 0.1% very severe airflow limitation. Most patients with airflow limitation (70.6%) had no previous spirometry testing or diagnosed pulmonary disease. Airflow limitation was associated with greater respiratory symptomatology, impaired health status, and more frequent emergency room visits (P < 0.05). Airflow limitation compatible with chronic obstructive pulmonary disease affects almost one-third of patients with ischemic heart disease. Although airflow limitation is associated with additional morbidity and societal burden, it is largely undiagnosed and untreated. Clinical trial registered with www.clinicaltrials.gov (NCT 01485159).

Investigation of airflow effects on the dielectric barrier discharge with single/double discharge channel arrangement

NASA Astrophysics Data System (ADS)

Fan, Zhihui; Yan, Huijie; Liu, Yidi; Guo, Hongfei; Wang, Yuying; Ren, Chunsheng

2018-05-01

Atmospheric-pressure dielectric barrier discharge (DBD) with airflow participation has been widely used in recent years. In this paper, effects of airflow on DBD characteristics are experimentally investigated by single/double pin-to-plate DBD arrangements with an AC exciting source. The discharge electrical characteristics and the movements of discharge channels in airflow are investigated with a single pin electrode arrangement. The current intensities increase in positive cycles and decrease in negative cycles with the increase in airflow velocity. The transition from a filamentary discharge to a diffuse discharge is observed under certain airflow conditions, and the discharge channels move with the airflow with a movement velocity less than the corresponding airflow velocity. In the cases of double pin electrode arrangements, the repulsion between double pin discharge channels is apparent at a 10 mm distance but is not obvious at a 20 mm distance. When the airflow is introduced into the discharge gap, not as in the case of single pin electrode arrangement, the movements of discharge channels in airflow are affected by adjacent discharge channels. The corresponding reasons are analyzed in the paper.

"Barnacle Bill" and Surrounding from Super-Pan

NASA Image and Video Library

1997-10-14

This is an image from the super-pan sequence. Of importance are some of the features around the rock nicknamed Barnacle Bill in the left foreground. The rock shows a "streamlined tail" composed of particles deposited by wind on the leeward (downwind) side of the rock. Also seen is a "moat" around the opposite (windward) side of the rock where either erosion (or non-deposition) of fine sediment has occurred. Mars Pathfinder scientist believe that the wind blowing over and around rocks like Barnacle Bill creates an airflow pattern wherein a buffer zone is formed immediately upwind of the rock and airflow patterns keep sediment from being deposited directly upwind of Barnacle Bill. On the downwind side, however, the airflow is complex and a small wake and tapered "dead air zone" form. Sediment can be deposited within this region, the shape of the formed deposit corresponds to the airflow patterns that exist behind the rock. Similar features have been observed at the Viking landing sites, and are thought to form under high wind conditions during the autumn and winter seasons in the northern hemisphere. This image mosaic was processed by the U.S. Geological Survey in support of the NASA/JPL Mars Pathfinder Mars Mission. Sojourner spent 83 days of a planned seven-day mission exploring the Martian terrain, acquiring images, and taking chemical, atmospheric and other measurements. The final data transmission received from Pathfinder was at 10:23 UTC on September 27, 1997. Although mission managers tried to restore full communications during the following five months, the successful mission was terminated on March 10, 1998. http://photojournal.jpl.nasa.gov/catalog/PIA00982

Impact of airborne particle size, acoustic airflow and breathing pattern on delivery of nebulized antibiotic into the maxillary sinuses using a realistic human nasal replica.

PubMed

Leclerc, Lara; Pourchez, Jérémie; Aubert, Gérald; Leguellec, Sandrine; Vecellio, Laurent; Cottier, Michèle; Durand, Marc

2014-09-01

Improvement of clinical outcome in patients with sinuses disorders involves targeting delivery of nebulized drug into the maxillary sinuses. We investigated the impact of nebulization conditions (with and without 100 Hz acoustic airflow), particle size (9.9 μm, 2.8 μm, 550 nm and 230 nm) and breathing pattern (nasal vs. no nasal breathing) on enhancement of aerosol delivery into the sinuses using a realistic nasal replica developed by our team. After segmentation of the airways by means of high-resolution computed tomography scans, a well-characterized nasal replica was created using a rapid prototyping technology. A total of 168 intrasinus aerosol depositions were performed with changes of aerosol particle size and breathing patterns under different nebulization conditions using gentamicin as a marker. The results demonstrate that the fraction of aerosol deposited in the maxillary sinuses is enhanced by use of submicrometric aerosols, e.g. 8.155 ± 1.476 mg/L of gentamicin in the left maxillary sinus for the 2.8 μm particles vs. 2.056 ± 0.0474 for the 550 nm particles. Utilization of 100-Hz acoustic airflow nebulization also produced a 2- to 3-fold increase in drug deposition in the maxillary sinuses (e.g. 8.155 ± 1.476 vs. 3.990 ± 1.690 for the 2.8 μm particles). Our study clearly shows that optimum deposition was achieved using submicrometric particles and 100-Hz acoustic airflow nebulization with no nasal breathing. It is hoped that our new respiratory nasal replica will greatly facilitate the development of more effective delivery systems in the future.

Severity of Airflow Obstruction in Chronic Obstructive Pulmonary Disease (COPD): Proposal for a New Classification.

PubMed

Coton, Sonia; Vollmer, William M; Bateman, Eric; Marks, Guy B; Tan, Wan; Mejza, Filip; Juvekar, Sanjay; Janson, Christer; Mortimer, Kevin; P A, Mahesh; Buist, A Sonia; Burney, Peter G J

2017-10-01

Current classifications of Chronic Obstructive Pulmonary Disease (COPD) severity are complex and do not grade levels of obstruction. Obstruction is a simpler construct and independent of ethnicity. We constructed an index of obstruction severity based on the FEV 1 /FVC ratio, with cut-points dividing the Burden of Obstructive Lung Disease (BOLD) study population into four similarly sized strata to those created by the GOLD criteria that uses FEV 1 . We measured the agreement between classifications and the validity of the FEV 1 -based classification in identifying the level of obstruction as defined by the new groupings. We compared the strengths of association of each classification with quality of life (QoL), MRC dyspnoea score and the self-reported exacerbation rate. Agreement between classifications was only fair. FEV 1 -based criteria for moderate COPD identified only 79% of those with moderate obstruction and misclassified half of the participants with mild obstruction as having more severe COPD. Both scales were equally strongly associated with QoL, exertional dyspnoea and respiratory exacerbations. Severity assessed using the FEV 1 /FVC ratio is only in moderate agreement with the severity assessed using FEV 1 but is equally strongly associated with other outcomes. Severity assessed using the FEV 1 /FVC ratio is likely to be independent of ethnicity.

Experimental and modelling study of the effect of airflow orientation with respect to strip electrode on ozone production of surface dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Mikeš, J.; Pekárek, S.; Soukup, I.

2016-11-01

This study examines the effect of airflow orientation with respect to the strip active electrode on concentration of ozone and nitrogen dioxide produced in a planar generator based on the surface dielectric barrier discharge. The orientation of the airflow was tested in parallel and perpendicular with respect to the strips. It was found that in the investigated range of average discharge power, the ozone concentration increases approximately by 25% when airflow was oriented in parallel with respect to the strips in comparison with perpendicular orientation of the airflow. Similarly the increase of nitrogen dioxide concentration was observed for parallel orientation of the airflow with respect to the strips in comparison with the perpendicular orientation of the airflow. Within the range of wavelengths from 250 to 1100 nm, the changes of intensities of spectral lines associated with airflow orientation have been observed. A 3D numerical model describing ion trajectories and airflow patterns have also been developed.

Power requirement of rotating rods in airflow

NASA Technical Reports Server (NTRS)

Barna, P. S.; Crossman, G. R.

1974-01-01

Experiments were performed to determine the power required for rotating a rotor disc fitted with a number of radially arranged rods placed into a ducted airflow. An array of stationary rods, also radially arranged, were placed upstream close to the rotor with a small gap between the rods to cause wake interference. The results show that power increased with increasing airflow and the rate of increase varied considerably. At lower values of airflow the rate of increase was larger than at higher airflow and definite power peaks occurred at certain airflow rates, where the power attained a maximum within the test airflow range. During the test a maximum blade passage frequency of 2037 Hz was attained.

Airflow obstruction, atherosclerosis and cardiovascular risk factors in the AGES Reykjavik study.

PubMed

Gudmundsson, Gunnar; Margretardottir, Olof Birna; Sigurdsson, Martin Ingi; Harris, Tamara B; Launer, Lenore J; Sigurdsson, Sigurdur; Olafsson, Orn; Aspelund, Thor; Gudnason, Vilmundur

2016-09-01

Airflow limitation, i.e. reduced forced expiratory volume in 1-s (FEV1), is associated with increased prevalence of atherosclerosis, however, causal mechanisms remain elusive. The objective of the study was to determine if the association between airflow obstruction and markers of atherosclerosis is mediated by systemic inflammation. 1154 subjects from the longitudinal AGES Reykjavik study were included. Population characteristics, systemic inflammation markers from blood (white blood cell counts (WBC) and level of C-reactive protein (CRP)) were compared between patients with and without airflow limitation defined by reduced FEV1 on spirometry. Atherosclerosis burden was quantified by measurements of coronary artery calcium, aortic arch and distal aortic calcification in addition to carotid intimal media thickness (CIMT). Subjects were split into four groups according to smoking status and whether airflow limitation was present. There was a higher overall burden of atherosclerosis in ever-smokers compared to never-smokers, and in individuals with airflow obstruction compared to individuals without airflow obstruction. After adjusting for population characteristics, Framingham cardiovascular risk factors and markers of systemic inflammation (WBC and CRP), there was a significantly increased aortic arch and distal aorta calcification and higher CIMT measurement in individuals with airflow obstruction compared to individuals without airflow obstruction. After adjusting for population characteristics, Framingham cardiovascular risk factors and markers of systemic inflammation (WBC and CRP), there was a significantly increased aortic arch and distal aorta calcification and higher CIMT measurement in individuals with airflow obstruction compared to individuals without airflow obstruction. Systemic inflammation (WBC and CRP) does not appear to mediate the association between airflow limitation and atherosclerosis. Only airflow limitation and not systemic inflammation (WBC and CRP) appears to be an independent predictor of atherosclerosis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Correlation of VHI-10 to voice laboratory measurements across five common voice disorders.

PubMed

Gillespie, Amanda I; Gooding, William; Rosen, Clark; Gartner-Schmidt, Jackie

2014-07-01

To correlate change in Voice Handicap Index (VHI)-10 scores with corresponding voice laboratory measures across five voice disorders. Retrospective study. One hundred fifty patients aged >18 years with primary diagnosis of vocal fold lesions, primary muscle tension dysphonia-1, atrophy, unilateral vocal fold paralysis (UVFP), and scar. For each group, participants with the largest change in VHI-10 between two periods (TA and TB) were selected. The dates of the VHI-10 values were linked to corresponding acoustic/aerodynamic and audio-perceptual measures. Change in voice laboratory values were analyzed for correlation with each other and with VHI-10. VHI-10 scores were greater for patients with UVFP than other disorders. The only disorder-specific correlation between voice laboratory measure and VHI-10 was average phonatory airflow in speech for patients with UVFP. Average airflow in repeated phonemes was strongly correlated with average airflow in speech (r=0.75). Acoustic measures did not significantly change between time points. The lack of correlations between the VHI-10 change scores and voice laboratory measures may be due to differing constructs of each measure; namely, handicap versus physiological function. Presuming corroboration between these measures may be faulty. Average airflow in speech may be the most ecologically valid measure for patients with UVFP. Although aerodynamic measures changed between the time points, acoustic measures did not. Correlations to VHI-10 and change between time points may be found with other acoustic measures. Copyright © 2014 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

Contamination control in HVAC systems for aseptic processing area. Part I: Case study of the airflow velocity in a unidirectional airflow workstation with computational fluid dynamics.

PubMed

Ogawa, M

2000-01-01

A unidirectional airflow workstation for processing a sterile pharmaceutical product is required to be "Grade A," according to EU-GMP and WHO-GMP. These regulations have employed the wording of "laminar airflow" for unidirectional airflow, with an unclear definition given. This seems to have allowed many reports to describe discussion of airflow velocity only. The guidance values as to the velocity are expressed in various words of 90 ft/min, 0.45 m/sec, 0.3 m/sec, +/- 20%, or "homogeneous air speed." It has been also little clarified how variation in airflow velocity gives influences on contamination control of a workstation working with varying key characteristics, such as ceiling height, internal heat load, internal particle generation, etc. The present author has revealed following points from a case study using Computational Fluid Dynamics: the airflow characteristic in Grade A area shows no significant changes with varying the velocity of supplied airflow, and the particles generated from the operator will be exhausted outside Grade A area without contamination.

FoilSim: Basic Aerodynamics Software Created

NASA Technical Reports Server (NTRS)

Peterson, Ruth A.

1999-01-01

FoilSim is interactive software that simulates the airflow around various shapes of airfoils. The graphical user interface, which looks more like a video game than a learning tool, captures and holds the students interest. The software is a product of NASA Lewis Research Center s Learning Technologies Project, an educational outreach initiative within the High Performance Computing and Communications Program (HPCCP).This airfoil view panel is a simulated view of a wing being tested in a wind tunnel. As students create new wing shapes by moving slider controls that change parameters, the software calculates their lift. FoilSim also displays plots of pressure or airspeed above and below the airfoil surface.

Theoretical Analysis of Maximum Flow Declination Rate versus Maximum Area Declination Rate in Phonation

ERIC Educational Resources Information Center

Titze, Ingo R.

2006-01-01

Purpose: Maximum flow declination rate (MFDR) in the glottis is known to correlate strongly with vocal intensity in voicing. This declination, or negative slope on the glottal airflow waveform, is in part attributable to the maximum area declination rate (MADR) and in part to the overall inertia of the air column of the vocal tract (lungs to…

A Prototype Flight-Deck Airflow Hazard Visualization System

NASA Technical Reports Server (NTRS)

Aragon, Cecilia R.

2004-01-01

Airflow hazards such as turbulence, vortices, or low-level wind shear can pose a threat to landing aircraft and are especially dangerous to helicopters. Because pilots usually cannot see airflow, they may be unaware of the extent of the hazard. We have developed a prototype airflow hazard visual display for use in helicopter cockpits to alleviate this problem. We report on the results of a preliminary usability study of our airflow hazard visualization system in helicopter-shipboard operations.

Impact of acoustic airflow on intrasinus drug deposition: New insights into the vibrating mode and the optimal acoustic frequency to enhance the delivery of nebulized antibiotic.

PubMed

Leclerc, Lara; Merhie, Amira El; Navarro, Laurent; Prévôt, Nathalie; Durand, Marc; Pourchez, Jérémie

2015-10-15

We investigated the impact of vibrating acoustic airflow, the high frequency (f≥100 Hz) and the low frequency (f≤45 Hz) sound waves, on the enhancement of intrasinus drug deposition. (81m)Kr-gas ventilation study was performed in a plastinated human cast with and without the addition of vibrating acoustic airflow. Similarly, intrasinus drug deposition in a nasal replica using gentamicin as a marker was studied with and without the superposition of different modes of acoustic airflow. Ventilation experiments demonstrate that no sinus ventilation was observed without acoustic airflow although sinus ventilation occurred whatever the modes of acoustic airflow applied. Intrasinus drug deposition experiments showed that the high frequency acoustic airflow led to 4-fold increase in gentamicin deposition into the left maxillary sinus and to 2-fold deposition increase into the right maxillary sinus. Besides, the low frequency acoustic airflow demonstrated a significant increase of 4-fold and 2-fold in the right and left maxillary sinuses, respectively. We demonstrated the benefit of different modes of vibrating acoustic airflow for maxillary sinus ventilation and intrasinus drug deposition. The degree of gentamicin deposition varies as a function of frequency of the vibrating acoustic airflow and the geometry of the ostia. Copyright © 2015 Elsevier B.V. All rights reserved.

Turbojet-exhaust-nozzle secondary-airflow pumping as an exit control of an inlet-stability bypass system for a Mach 2.5 axisymmetric mixed-compression inlet. [Lewis 10- by 10-ft. supersonic wind tunnel test

NASA Technical Reports Server (NTRS)

Sanders, B. W.

1980-01-01

The throat of a Mach 2.5 inlet that was attached to a turbojet engine was fitted with large, porous bleed areas to provide a stability bypass system that would allow a large, stable airflow range. Exhaust-nozzle, secondary-airflow pumping was used as the exit control for the stability bypass airflow. Propulsion system response and stability bypass performance were obtained for several transient airflow disturbances, both internal and external. Internal airflow disturbances included reductions in overboard bypass airflow, power lever angle, and primary-nozzle area, as well as compressor stall. Nozzle secondary pumping as a stability bypass exit control can provide the inlet with a large stability margin with no adverse effects on propulsion system performance.

The Measurement of Airflow Using Singing Helmet That Allows Free Movement of the Jaw.

PubMed

Jiang, Jack J; Hanna, Rewais B; Willey, Malachi V; Rieves, Adam

2016-11-01

Airflow measurement is a useful method of evaluating laryngeal physiology. We introduce a noninvasive device that measures airflow without restricting jaw movement or requiring phonation into a mouthpiece, thus facilitating measurement during singing and connected speech. Validation and human subject trials were conducted. Airflow measurements were obtained from 16 male and 16 female subjects during singing, speech, and constant vowel production tasks. A similar helmet was designed by Stevens and Mead in 1968. The new device validity was evaluated by comparing the measured volume of air to a known volume of administered air using a calibration syringe. Subjects were asked to voice sustained vowels at low, medium, and high vocal intensity, read two sentences at a conversational volume, and perform different singing exercises while airflow was recorded. The device accurately and reliably measured airflow with mean airflow values falling within previously published ranges. There was an experimentally determined response time of 0.173 ± 0.014 seconds. Subjects were able to comfortably perform speech and singing exercises. Male subjects had higher airflow for all sustained vowels (P < 0.05). Airflow was higher for abduction rather than adduction sentences (P < 0.05). No other portable device has been shown to measure airflow during singing and speech while allowing for free movement of the jaw. This device provides a more natural environment to measure airflow that could be used to help evaluate laryngeal function and aid in singing training. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

The 3-D numerical study of airflow in the compressor/combustor prediffuser and dump diffuser of an industrial gas turbine

NASA Technical Reports Server (NTRS)

Agrawal, Ajay K.; Yang, Tah-Teh

1993-01-01

This paper describes the 3D computations of a flow field in the compressor/combustor diffusers of an industrial gas turbine. The geometry considered includes components such as the combustor support strut, the transition piece and the impingement sleeve with discrete cooling air holes on its surface. Because the geometry was complex and 3D, the airflow path was divided into two computational domains sharing an interface region. The body-fitted grid was generated independently in each of the two domains. The governing equations for incompressible Navier-Stokes equations were solved using the finite volume approach. The results show that the flow in the prediffuser is strongly coupled with the flow in the dump diffuser and vice versa. The computations also revealed that the flow in the dump diffuser is highly nonuniform.

The dune effect on sand-transporting winds on Mars.

PubMed

Jackson, Derek W T; Bourke, Mary C; Smyth, Thomas A G

2015-11-05

Wind on Mars is a significant agent of contemporary surface change, yet the absence of in situ meteorological data hampers the understanding of surface-atmospheric interactions. Airflow models at length scales relevant to landform size now enable examination of conditions that might activate even small-scale bedforms (ripples) under certain contemporary wind regimes. Ripples have the potential to be used as modern 'wind vanes' on Mars. Here we use 3D airflow modelling to demonstrate that local dune topography exerts a strong influence on wind speed and direction and that ripple movement likely reflects steered wind direction for certain dune ridge shapes. The poor correlation of dune orientation with effective sand-transporting winds suggests that large dunes may not be mobile under modelled wind scenarios. This work highlights the need to first model winds at high resolution before inferring regional wind patterns from ripple movement or dune orientations on the surface of Mars today.

The dune effect on sand-transporting winds on Mars

PubMed Central

Jackson, Derek W. T.; Bourke, Mary C; Smyth, Thomas A. G.

2015-01-01

Wind on Mars is a significant agent of contemporary surface change, yet the absence of in situ meteorological data hampers the understanding of surface–atmospheric interactions. Airflow models at length scales relevant to landform size now enable examination of conditions that might activate even small-scale bedforms (ripples) under certain contemporary wind regimes. Ripples have the potential to be used as modern ‘wind vanes' on Mars. Here we use 3D airflow modelling to demonstrate that local dune topography exerts a strong influence on wind speed and direction and that ripple movement likely reflects steered wind direction for certain dune ridge shapes. The poor correlation of dune orientation with effective sand-transporting winds suggests that large dunes may not be mobile under modelled wind scenarios. This work highlights the need to first model winds at high resolution before inferring regional wind patterns from ripple movement or dune orientations on the surface of Mars today. PMID:26537669

Stimulation of Electro-Olfactogram Responses in the Main Olfactory Epithelia by Airflow Depend on the Type 3 Adenylyl Cyclase

PubMed Central

Chen, Xuanmao; Xia, Zhengui; Storm, Daniel R.

2012-01-01

Cilia of olfactory sensory neurons (OSN) are the primary sensory organelles for olfaction. The detection of odorants by the main olfactory epithelium (MOE) depends on coupling of odorant receptors to the type 3 adenylyl cyclase (AC3) in olfactory cilia. We monitored the effect of airflow on electro-olfactogram (EOG) responses and found that the MOE of mice can sense mechanical forces generated by airflow. The airflow-sensitive EOG response in the MOE was attenuated when cAMP was increased by odorants or by forskolin suggesting a common mechanism for airflow and odorant detection. In addition, the sensitivity to airflow was significantly impaired in the MOE from AC3−/− mice. We conclude that AC3 in the MOE is required for detecting the mechanical force of airflow, which in turn may regulate odorant perception during sniffing. PMID:23136416

Estimating Engine Airflow in Gas-Turbine Powered Aircraft with Clean and Distorted Inlet Flows

NASA Technical Reports Server (NTRS)

Williams, J. G.; Steenken, W. G.; Yuhas, A. J.

1996-01-01

The P404-GF-400 Powered F/A-18A High Alpha Research Vehicle (HARV) was used to examine the impact of inlet-generated total-pressure distortion on estimating levels of engine airflow. Five airflow estimation methods were studied. The Reference Method was a fan corrected airflow to fan corrected speed calibration from an uninstalled engine test. In-flight airflow estimation methods utilized the average, or individual, inlet duct static- to total-pressure ratios, and the average fan-discharge static-pressure to average inlet total-pressure ratio. Correlations were established at low distortion conditions for each method relative to the Reference Method. A range of distorted inlet flow conditions were obtained from -10 deg. to +60 deg. angle of attack and -7 deg. to +11 deg. angle of sideslip. The individual inlet duct pressure ratio correlation resulted in a 2.3 percent airflow spread for all distorted flow levels with a bias error of -0.7 percent. The fan discharge pressure ratio correlation gave results with a 0.6 percent airflow spread with essentially no systematic error. Inlet-generated total-pressure distortion and turbulence had no significant impact on the P404-GE400 engine airflow pumping. Therefore, a speed-flow relationship may provide the best airflow estimate for a specific engine under all flight conditions.

Review on airflow in unsaturated zones induced by natural forcings

NASA Astrophysics Data System (ADS)

Kuang, Xingxing; Jiao, Jiu Jimmy; Li, Hailong

2013-10-01

Subsurface airflow in unsaturated zones induced by natural forcings is of importance in many environmental and engineering fields, such as environmental remediation, water infiltration and groundwater recharge, coastal soil aeration, mine and tunnel ventilation, and gas exchange between soil and atmosphere. This review synthesizes the published literature on subsurface airflow driven by natural forcings such as atmospheric pressure fluctuations, topographic effect, water table fluctuations, and water infiltration. The present state of knowledge concerning the mechanisms, analytical and numerical models, and environmental and engineering applications related to the naturally occurring airflow is discussed. Airflow induced by atmospheric pressure fluctuations is studied the most because of the applications to environmental remediation and transport of trace gases from soil to atmosphere, which are very important in understanding biogeochemical cycling and global change. Airflow induced by infiltration is also an extensively investigated topic because of its implications in rainfall infiltration and groundwater recharge. Airflow induced by water table fluctuations is important in coastal areas because it plays an important role in coastal environmental remediation and ecological systems. Airflow induced by topographic effect is studied the least. However, it has important applications in unsaturated zone gas transport and natural ventilation of mines and tunnels. Finally, the similarities and differences in the characteristics of the air pressure and airflow are compared and future research efforts are recommended.

Real-time visualization and analysis of airflow field by use of digital holography

NASA Astrophysics Data System (ADS)

Di, Jianglei; Wu, Bingjing; Chen, Xin; Liu, Junjiang; Wang, Jun; Zhao, Jianlin

2013-04-01

The measurement and analysis of airflow field is very important in fluid dynamics. For airflow, smoke particles can be added to visually observe the turbulence phenomena by particle tracking technology, but the effect of smoke particles to follow the high speed airflow will reduce the measurement accuracy. In recent years, with the advantage of non-contact, nondestructive, fast and full-field measurement, digital holography has been widely applied in many fields, such as deformation and vibration analysis, particle characterization, refractive index measurement, and so on. In this paper, we present a method to measure the airflow field by use of digital holography. A small wind tunnel model made of acrylic glass is built to control the velocity and direction of airflow. Different shapes of samples such as aircraft wing and cylinder are placed in the wind tunnel model to produce different forms of flow field. With a Mach-Zehnder interferometer setup, a series of digital holograms carrying the information of airflow filed distributions in different states are recorded by CCD camera and corresponding holographic images are numerically reconstructed from the holograms by computer. Then we can conveniently obtain the velocity or pressure information of the airflow deduced from the quantitative phase information of holographic images and visually display the airflow filed and its evolution in the form of a movie. The theory and experiment results show that digital holography is a robust and feasible approach for real-time visualization and analysis of airflow field.

Do surgeons and surgical facilities disturb the clean air distribution close to a surgical patient in an orthopedic operating room with laminar airflow?

PubMed

Cao, Guangyu; Storås, Madeleine C A; Aganovic, Amar; Stenstad, Liv-Inger; Skogås, Jan Gunnar

2018-05-04

Airflow distribution in the operating room plays an important role in ensuring a clean operating microenvironment and preventing surgical site infections (SSIs) caused by airborne contaminations. The objective of this study was to characterize the airflow distribution in proximity to a patient in an orthopedic operating room. Experimental measurements were conducted in a real operating room at St. Olav's Hospital, Norway, with a laminar airflow system. Omnidirectional anemometers were used to investigate the air distribution in the operating zone, and 4 different cases were examined with a real person and a thermal manikin. This study showed that the downward airflow from the laminar airflow system varies in each case with different surgical arrangement, such as the position of the operating lamp. The results indicate that the interaction of thermal plumes from a patient and the downward laminar airflow may dominate the operating microenvironment. The airflow distribution in proximity to a patient is influenced by both the surgical facility and the presence of medical staff. A thermal manikin may be an economical and practical way to study the interaction of thermal plumes and downward laminar airflow. The provision of higher clean airflow rate in the operating microenvironment may be an effective way to prevent the development of SSIs caused by indoor airborne contamination. Copyright © 2018 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Assessing Airflow Sensitivity to Healthy and Diseased Lung Conditions in a Computational Fluid Dynamics Model Validated In Vitro.

PubMed

Sul, Bora; Oppito, Zachary; Jayasekera, Shehan; Vanger, Brian; Zeller, Amy; Morris, Michael; Ruppert, Kai; Altes, Talissa; Rakesh, Vineet; Day, Steven; Robinson, Risa; Reifman, Jaques; Wallqvist, Anders

2018-05-01

Computational models are useful for understanding respiratory physiology. Crucial to such models are the boundary conditions specifying the flow conditions at truncated airway branches (terminal flow rates). However, most studies make assumptions about these values, which are difficult to obtain in vivo. We developed a computational fluid dynamics (CFD) model of airflows for steady expiration to investigate how terminal flows affect airflow patterns in respiratory airways. First, we measured in vitro airflow patterns in a physical airway model, using particle image velocimetry (PIV). The measured and computed airflow patterns agreed well, validating our CFD model. Next, we used the lobar flow fractions from a healthy or chronic obstructive pulmonary disease (COPD) subject as constraints to derive different terminal flow rates (i.e., three healthy and one COPD) and computed the corresponding airflow patterns in the same geometry. To assess airflow sensitivity to the boundary conditions, we used the correlation coefficient of the shape similarity (R) and the root-mean-square of the velocity magnitude difference (Drms) between two velocity contours. Airflow patterns in the central airways were similar across healthy conditions (minimum R, 0.80) despite variations in terminal flow rates but markedly different for COPD (minimum R, 0.26; maximum Drms, ten times that of healthy cases). In contrast, those in the upper airway were similar for all cases. Our findings quantify how variability in terminal and lobar flows contributes to airflow patterns in respiratory airways. They highlight the importance of using lobar flow fractions to examine physiologically relevant airflow characteristics.

The Impact of Smoking on Airflow Limitation in Subjects with History of Asthma and Inactive Tuberculosis

PubMed Central

Kim, Hyun Jung; Baek, Seunghee; Kim, Hee Jin; Lee, Jae Seung; Oh, Yeon-Mok; Lee, Sang-Do; Lee, Sei Won

2015-01-01

Background Although smoking is the most important and modifiable cause of chronic obstructive pulmonary disease (COPD), other risk factors including asthma and tuberculosis (TB) are also associated. It is common for COPD patients to have more than one of these risk factors. The aims of this study were to determine the prevalence of airflow limitation (FEV1/FVC<0.7) according to the risk factors and to investigate their impact and interaction in airflow limitation. Methods From the Korean National Health and Nutrition Examination Survey between 2008 and 2012, we analyzed participants over 40 years of age by spirometry, chest radiograph and questionnaire about asthma and smoking history. Results Of 12,631 participants, 1,548 (12.3%) had airflow limitation. The prevalence of airflow limitation in smokers (≥10 pack-year), asthmatics, and those with inactive TB was 23.9%, 32.1%, and 33.6%. The prevalence increased with the number of risk factors: 86.1% had airflow limitation if they had all three risk factors. Impacts of inactive TB and asthma on airflow limitation were equivalent to 47 and 69 pack-years of smoking, respectively. Airflow limitation resulted from lower levels of smoking in those with inactive TB and asthma. A potential interaction between smoking and inactive tuberculosis in the development of airflow limitation was identified (p = 0.054). Conclusions Asthma and inactive TB lesions increase susceptibility to smoking in the development of airflow limitation. People with these risk factors should be seen as a major target population for anti-smoking campaigns to prevent COPD. PMID:25915938

Investigating the effects of laryngotracheal stenosis on upper airway aerodynamics.

PubMed

Cheng, Tracy; Carpenter, David; Cohen, Seth; Witsell, David; Frank-Ito, Dennis O

2018-04-01

Very little is known about the impact of laryngotracheal stenosis (LTS) on inspiratory airflow and resistance, especially in air hunger states. This study investigates the effect of LTS on airway resistance and volumetric flow across three different inspiratory pressures. Head-and-neck computed tomography scans of 11 subjects from 2010 to 2016 were collected. Three-dimensional reconstructions of the upper airway from the nostrils to carina, including the oral cavity, were created for one subject with a normal airway and for 10 patients with LTS. Airflow simulations were conducted using computational fluid dynamics modeling at three different inspiratory pressures (10, 25, 40 pascals [Pa]) for all subjects under two scenarios: 1) inspiration through nostrils only (MC), and 2) through both nostrils and mouth (MO). Volumetric flows in the normal subject at the three inspiratory pressures were considerably higher (MC: 11.8-26.1 L/min; MO: 17.2-36.9 L/min) compared to those in LTS (MC: 2.86-6.75 L/min; MO: 4.11-9.00 L/min). Airway resistances in the normal subject were 0.051 to 0.092 pascal seconds per milliliter (Pa.s)/mL (MC) and 0.035-0.065 Pa.s/mL (MO), which were approximately tenfold lower than those of subjects with LTS: 0.39 to 0.89 Pa.s/mL (MC) and 0.45 to 0.84 Pa.s/mL (MO). Furthermore, subjects with glottic stenosis had the greatest resistance, whereas subjects with subglottic stenosis had the greatest variability in resistance. Subjects with tracheal stenosis had the lowest resistance. This pilot study demonstrates that LTS increases resistance and decreases airflow. Mouth breathing significantly improved airflow and resistance but cannot completely compensate for the effects of stenosis. Furthermore, location of stenosis appears to modulate the effect of the stenosis on resistance differentially. NA. Laryngoscope, 128:E141-E149, 2018. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

Distribution and Room Air Mixing Risks to Retrofitted Homes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burdick, A.

2014-12-01

An energy efficiency upgrade reduces a home’s heating and cooling load. If the load reduction is great enough and the heating, ventilation, and air conditioning system warrants replacement, that system is often upgraded with a more efficient, lower capacity system that meets the load of the upgraded house. For a single-story house with floor supply air diffusers, the ducts often are removed and upgraded. For houses with ducts that are embedded in walls, the cost of demolition precludes the replacement of ducts. The challenge with the use of existing ducts is that the reduced airflow creates a decreased throw atmore » the supply registers, and the supply air and room air do not mix well, leading to potential thermal comfort complaints. This project investigates this retrofit scenario. The issues and solutions discussed here are relevant to all climate zones, with emphasis on climates that require cooling. In this project, IBACOS performed load calculations for a two-story 1960s house and characterized duct sizes and layouts based on industry “rules of thumb” (Herk et al. 2014). The team performed duct-sizing calculations for unaltered ducts and post-retrofit airflows and examined airflow velocities and pressure changes with respect to various factors. The team then used a mocked-up duct and register setup to measure the characteristics of isothermal air—to reduce the effects of buoyancy from the observations—passing through the duct and leaving the register.« less

Experimental Investigation of the Induced Airflow of Corona Discharge

NASA Astrophysics Data System (ADS)

Huang, Yong; Zhang, Xin; Wang, Xun-Nian; Wang, Wan-Bo; Huang, Zong-Bo; Li, Hua-Xing

2013-09-01

In order to improve the acceleration effect of corona discharge acting on air, we present an experimental study on the induced airflow produced by corona discharge between two parallel electrodes. The parameters investigated are the type of electrodes, actuation voltage and the distance in the absence of free airflow. The induced flow velocity is measured directly in the accelerated region using the particle image velocimetry technology. The results show that if corona discharge is not developed into arc discharge, the induced airflow velocity increases nearly linearly with the applied voltage and the maximum induced airflow velocity near the needle electrode reaches 36 m/s. It is expected that in the future, the result can be referred to in the research about effect of active flow control to reach much higher induced airflow speed.

Airflows and turbulent flux measurements in mountainous terrain: Part 2: Mesoscale effects

USGS Publications Warehouse

Turnipseed, A.A.; Anderson, D.E.; Burns, S.; Blanken, P.D.; Monson, Russell K.

2004-01-01

The location of the Niwot Ridge Ameriflux site within the rocky mountains subjects it to airflows which are common in mountainous terrain. In this study, we examine the effects of some of these mesoscale features on local turbulent flux measurements; most notably, the formation of valley/mountain flows and mountain lee-side waves. The valley/mountain flows created local non-stationarities in the wind flow caused by the passage of a lee-side convergence zone (LCZ) in which upslope and downslope flows met in the vicinity of the measurement tower. During June-August, 2001, possible lee-side convergences were flagged for ???26% of all half-hour daytime flux measurement periods. However, there was no apparent loss of flux during these periods. On some relatively stable, summer nights, turbulence (designated via ??w), and scalar fluctuations (temperature and CO2, for example) exhibited periodicities that appeared congruent with passage of low frequency gravity waves (?? ??? 20 min). Spectral peaks at 0.0008 Hz (20 min) in both vertical velocity and scalar spectra were observed and indicated that 25-50% of the total scalar covariances were accounted for by the low frequency waves. During some periods of strong westerly winds (predominantly in winter), large mountain gravity waves were observed to form. Typically, the flux tower resided within a region of downslope "shooting flow", which created high turbulence, but had no detrimental effect on local flux measurements based on valid turbulence statistics and nearly complete energy budget closure. Periodically, we found evidence for re-circulating, rotor winds in the simultaneous time series of wind data from the Ameriflux tower site and a second meteorological site situated 8 km upslope and to the West. Only 14% of the half-hour time periods that we examined for a 4 month period in the winter of 2000-2001 indicated the possible existence of rotor winds. On average, energy budget closure was ???20% less during periods with rotor occurrence compared to those without. Results from this study demonstrate that the potential exists for relatively rare, yet significant influences of mesoscale wind flow patterns on the local half-hour flux measurements at this site. Occurrence of these events could be detected through examination of normal turbulence statistical parameters. ?? 2004 Elsevier B.V. All rights reserved.

Morphological response of a large-scale coastal blowout to a strong magnitude transport event

NASA Astrophysics Data System (ADS)

Delgado-Fernandez, Irene; Jackson, Derek; Smith, Alexander; Smyth, Thomas

2017-04-01

Large-scale blowouts are fundamental features of many coastal dune fields in temperate areas around the world. These distinctive erosional (mostly unvegetated) landform features are often characterised by a significant depression area and a connected depositional lobe at their downwind edges. These areas also provide important transport corridors to inland parts of the dune system and can provide ideal habitats for specialist flora and fauna as well as helping to enhance landscape diversity. The actual morphology and shape/size of blowouts can significantly modify the overlying atmospheric boundary layer of the wind, influencing wind flow steering and intensity within the blowout, and ultimately aeolian sediment transport. While investigations of morphological changes within blowouts have largely focused on the medium (months) to long (annual/decadal) temporal scale, studies of aeolian transport dynamics within blowouts have predominantly focused on the short-term (event) scale. Work on wind-transport processes in blowouts is still relatively rare, with ad-hoc studies providing only limited information on airflow and aeolian transport. Large-scale blowouts are characterised by elongated basins that can reach hundreds of meters, potentially resulting in airflow and transport dynamics that are very different from their smaller scale counterparts. This research focuses on a short-term, strong wind event measured at the Devil's Hole blowout (Sefton dunes, NW England), a large-scale blowout feature approximately 300 m in length and 100 m in width. In situ measurements of airflow and aeolian transport were collected during a short-term experiment on the 22nd October 2015. A total of twenty three, 3D ultrasonic anemometers, sand traps, and wenglor sensors were deployed in a spatial grid covering the distal end of the basin, walls, and depositional lobe. Terrestrial laser scanning (TLS) was used to quantify morphological changes within the blowout before and after the strong magnitude transport event. This allowed, for the first time, examination of the morphological response as a direct result of a high energy wind event as it passes through a large-scale blowout. Results indicate strong steering and acceleration of the wind along the blowout basin and up the south wall opposite to the incident regional winds. These accelerated flows generated very strong transport rates of up to 3 g/s along the basin, and moderate strong transport rates of up to 1.5 g/s up the steep north wall. The coupling of high-frequency wind events and transport response together with topographic changes defined by TLS data allows, for the first time, the ability to co-connect the morphological evolution of a coastal blowout landform with the localised driving processes.

Effects of mass airflow rate through an open-circuit gas quantification system when measuring carbon emissions.

PubMed

Gunter, Stacey A; Bradford, James A; Moffet, Corey A

2017-01-01

Methane (CH) and carbon dioxide (CO) represent 11 and 81%, respectively, of all anthropogenic greenhouse gas emissions. Agricultural CH emissions account for approximately 43% of all anthropogenic CH emissions. Most agricultural CH emissions are attributed to enteric fermentation within ruminant livestock; hence, the heightened interest in quantifying and mitigating this source. The automated, open-circuit gas quantification system (GQS; GreenFeed, C-Lock, Inc., Rapid City, SD) evaluated here can be placed in a pasture with grazing cattle and can measure their CH and CO emissions with spot sampling. However, improper management of the GQS can have an erroneous effect on emission estimates. One factor affecting the quality of emission estimates is the airflow rates through the GQS to ensure a complete capture of the breath cloud emitted by the animal. It is hypothesized that at lower airflow rates this cloud will be incompletely captured. To evaluate the effect of airflow rate through the GQS on emission estimates, a data set was evaluated with 758 CO and CH emission estimates with a range in airflows of 10.7 to 36.6 L/s. When airflow through the GQS was between 26.0 and 36.6 L/s, CO and CH emission estimates were not affected ( = 0.14 and 0.05, respectively). When airflow rates were less than 26.0 L/s, CO and CH emission estimates were lower and decreased as airflow rate decreased ( < 0.0001). We hypothesize that when airflow through the GQS decreases below 26 L/s, breath capture was incomplete and CO and CH emissions are underestimated. Maintaining mass airflow through a GQS at rates greater than 26 L/s is important for producing high quality CO and CH emission estimates.

Comparison of Respiratory Resistance Measurements Made with an Airflow Perturbation Device with Those from Impulse Oscillometry

PubMed Central

Pan, J.; Saltos, A.; Smith, D.; Johnson, A.; Vossoughi, J.

2013-01-01

The airflow perturbation device (APD) has been developed as a portable, easy to use, and a rapid response instrument for measuring respiratory resistance in humans. However, the APD has limited data validating it against the established techniques. This study used a mechanical system to simulate the normal range of human breathing to validate the APD with the clinically accepted impulse oscillometry (IOS) technique. The validation system consisted of a sinusoidal flow generator with ten standardized resistance configurations that were shown to represent a total range of resistances from 0.12 to 0.95 kPa·L−1 ·s (1.2–9.7 cm H2O·L−1 ·s). Impulse oscillometry measurements and APD measurements of the mechanical system were recorded and compared at a constant airflow of 0.15 L·s−1. Both the IOS and APD measurments were accurate in assessing nominal resistance. In addition, a strong linear relationship was observed between APD measurements and IOS measurements (R 2 = 0.999). A second series of measurements was made on ten human volunteers with external resistors added in their respiratory flow paths. Once calibrated with the mechanical system, the APD gave respiratory resistance measurements within 5% of IOS measurements. Because of their comparability to IOS measurements, APD measurements are shown to be valid representations of respiratory resistance. PMID:27006908

Fault tolerant attitude control for small unmanned aircraft systems equipped with an airflow sensor array.

PubMed

Shen, H; Xu, Y; Dickinson, B T

2014-11-18

Inspired by sensing strategies observed in birds and bats, a new attitude control concept of directly using real-time pressure and shear stresses has recently been studied. It was shown that with an array of onboard airflow sensors, small unmanned aircraft systems can promptly respond to airflow changes and improve flight performances. In this paper, a mapping function is proposed to compute aerodynamic moments from the real-time pressure and shear data in a practical and computationally tractable formulation. Since many microscale airflow sensors are embedded on the small unmanned aircraft system surface, it is highly possible that certain sensors may fail. Here, an adaptive control system is developed that is robust to sensor failure as well as other numerical mismatches in calculating real-time aerodynamic moments. The advantages of the proposed method are shown in the following simulation cases: (i) feedback pressure and wall shear data from a distributed array of 45 airflow sensors; (ii) 50% failure of the symmetrically distributed airflow sensor array; and (iii) failure of all the airflow sensors on one wing. It is shown that even if 50% of the airflow sensors have failures, the aircraft is still stable and able to track the attitude commands.

Coupling the Multizone Airflow and Contaminant Transport Software CONTAM with EnergyPlus Using Co-Simulation.

PubMed

Dols, W Stuart; Emmerich, Steven J; Polidoro, Brian J

2016-08-01

Building modelers need simulation tools capable of simultaneously considering building energy use, airflow and indoor air quality (IAQ) to design and evaluate the ability of buildings and their systems to meet today's demanding energy efficiency and IAQ performance requirements. CONTAM is a widely-used multizone building airflow and contaminant transport simulation tool that requires indoor temperatures as input values. EnergyPlus is a prominent whole-building energy simulation program capable of performing heat transfer calculations that require interzone and infiltration airflows as input values. On their own, each tool is limited in its ability to account for thermal processes upon which building airflow may be significantly dependent and vice versa. This paper describes the initial phase of coupling of CONTAM with EnergyPlus to capture the interdependencies between airflow and heat transfer using co-simulation that allows for sharing of data between independently executing simulation tools. The coupling is accomplished based on the Functional Mock-up Interface (FMI) for Co-simulation specification that provides for integration between independently developed tools. A three-zone combined heat transfer/airflow analytical BESTEST case was simulated to verify the co-simulation is functioning as expected, and an investigation of a two-zone, natural ventilation case designed to challenge the coupled thermal/airflow solution methods was performed.

[Phonatory airflow in the supraglottal space].

PubMed

Müsebeck, K; Rosenberg, H

1983-05-01

The phonatory airflow can be measured by means of a hot wire tube placed in the supraglottic space without tying down the tongue. The velocity of airflow above the glottis reaches values around c = 50 to 150 cm/s. The variations in airflow oscillations were recorded. The voice of the person under examination was picked up by a condenser microphone (Bruel & Kjaer No. 2112). According to D'Alembert's wave equation, the sound intensity is related to the velocity of the phonatory air stream. The validity of this statement has been confirmed by repeated testing. The fundamental frequency of voice and of the airflow were analysed synchronously by means of the Nicolet analyser. The air consumption is not utilized for sound production in phonation by breathing. A "hard" or "pressed" voice is associated with diminished or irregular air consumption. The method can be employed in assessing the conditions of phonetic airflow in normal and dysphonic voices.

Visualization of airflow growing soap bubbles

NASA Astrophysics Data System (ADS)

Al Rahbi, Hamood; Bock, Matthew; Ryu, Sangjin

2016-11-01

Visualizing airflow inside growing soap bubbles can answer questions regarding the fluid dynamics of soap bubble blowing, which is a model system for flows with a gas-liquid-gas interface. Also, understanding the soap bubble blowing process is practical because it can contribute to controlling industrial processes similar to soap bubble blowing. In this study, we visualized airflow which grows soap bubbles using the smoke wire technique to understand how airflow blows soap bubbles. The soap bubble blower setup was built to mimic the human blowing process of soap bubbles, which consists of a blower, a nozzle and a bubble ring. The smoke wire was placed between the nozzle and the bubble ring, and smoke-visualized airflow was captured using a high speed camera. Our visualization shows how air jet flows into the growing soap bubble on the ring and how the airflow interacts with the soap film of growing bubble.

Airflow attenuation and bed net utilization: observations from Africa and Asia.

PubMed

von Seidlein, Lorenz; Ikonomidis, Konstantin; Bruun, Rasmus; Jawara, Musa; Pinder, Margaret; Knols, Bart Gj; Knudsen, Jakob B

2012-06-15

Qualitative studies suggest that bed nets affect the thermal comfort of users. To understand and reduce this discomfort the effect of bed nets on temperature, humidity, and airflow was measured in rural homes in Asia and Africa, as well as in an experimental wind tunnel. Two investigators with architectural training selected 60 houses in The Gambia, Tanzania, Philippines, and Thailand. Data-loggers were used to measure indoor temperatures in hourly intervals over a 12 months period. In a subgroup of 20 houses airflow, temperature and humidity were measured at five-minute intervals for one night from 21.00 to 6.00 hrs inside and outside of bed nets using sensors and omni-directional thermo-anemometers. An investigator set up a bed net with a mesh size of 220 holes per inch 2 in each study household and slept under the bed net to simulate a realistic environment. The attenuation of airflow caused by bed nets of different mesh sizes was also measured in an experimental wind tunnel. The highest indoor temperatures (49.0 C) were measured in The Gambia. During the hottest months of the year the mean temperature at night (9 pm) was between 33.1 C (The Gambia) and 26.2 C (Thailand). The bed net attenuated the airflow from a minimum of 27% (Philippines) to a maximum of 71% (The Gambia). Overall the bed nets reduced airflow compared to un-attenuated airflow from 9 to 4 cm sec-1 or 52% (p<0.001). In all sites, no statistically significant difference in temperature or humidity was detected between the inside and outside of the bed net. Wind tunnel experiments with 11 different mesh-sized bed nets showed an overall reduction in airflow of 64% (range 55 - 71%) compared to un-attenuated airflow. As expected, airflow decreased with increasing net mesh size. Nets with a mesh of 136 holes inch-2 reduced airflow by 55% (mean; range 51 - 73%). A denser net (200 holes inch-2) attenuated airflow by 59% (mean; range 56 - 74%). Despite concerted efforts to increase the uptake of this intervention in many areas uptake remains poor. Bed nets reduce airflow, but have no influence on temperature and humidity. The discomfort associated with bed nets is likely to be most intolerable during the hottest and most humid period of the year, which frequently coincides with the peak of malaria vector densities and the force of pathogen transmission. These observations suggest thermal discomfort is a factor limiting bed net use and open a range of architectural possibilities to overcome this limitation.

Impact of Middle vs. Inferior Total Turbinectomy on Nasal Aerodynamics

PubMed Central

Dayal, Anupriya; Rhee, John S.; Garcia, Guilherme J. M.

2016-01-01

Objectives This computational study aims to: (1) Use virtual surgery to theoretically investigate the maximum possible change in nasal aerodynamics after turbinate surgery; (2) Quantify the relative contributions of the middle and inferior turbinates to nasal resistance and air conditioning; (3) Quantify to what extent total turbinectomy impairs the nasal air conditioning capacity. Study Design Virtual surgery and computational fluid dynamics (CFD). Setting Academic tertiary medical center. Subjects and Methods Ten patients with inferior turbinate hypertrophy were studied. Three-dimensional models of their nasal anatomies were built based on pre-surgery computed tomography scans. Virtual surgery was applied to create models representing either total inferior turbinectomy (TIT) or total middle turbinectomy (TMT). Airflow, heat transfer, and humidity transport were simulated at a 15 L/min steady-state inhalation rate. The surface area stimulated by mucosal cooling was defined as the area where heat fluxes exceed 50 W/cm2. Results In both virtual total turbinectomy models, nasal resistance decreased and airflow increased. However, the surface area where heat fluxes exceed 50 W/cm2 either decreased (TIT) or did not change significantly (TMT), suggesting that total turbinectomy may reduce the stimulation of cold receptors by inspired air. Nasal heating and humidification efficiencies decreased significantly after both TIT and TMT. All changes were greater in the TIT models than in the TMT models. Conclusion TIT yields greater increases in nasal airflow, but also impairs the nasal air conditioning capacity to a greater extent than TMT. Radical resection of the turbinates may decrease the surface area stimulated by mucosal cooling. PMID:27165673

Impact of Middle versus Inferior Total Turbinectomy on Nasal Aerodynamics.

PubMed

Dayal, Anupriya; Rhee, John S; Garcia, Guilherme J M

2016-09-01

This computational study aims to (1) use virtual surgery to theoretically investigate the maximum possible change in nasal aerodynamics after turbinate surgery, (2) quantify the relative contributions of the middle and inferior turbinates to nasal resistance and air conditioning, and (3) quantify to what extent total turbinectomy impairs the nasal air-conditioning capacity. Virtual surgery and computational fluid dynamics. Academic tertiary medical center. Ten patients with inferior turbinate hypertrophy were studied. Three-dimensional models of their nasal anatomies were built according to presurgery computed tomography scans. Virtual surgery was applied to create models representing either total inferior turbinectomy (TIT) or total middle turbinectomy (TMT). Airflow, heat transfer, and humidity transport were simulated at a steady-state inhalation rate of 15 L/min. The surface area stimulated by mucosal cooling was defined as the area where heat fluxes exceed 50 W/m(2). In both virtual total turbinectomy models, nasal resistance decreased and airflow increased. However, the surface area where heat fluxes exceed 50 W/m(2) either decreased (TIT) or did not change significantly (TMT), suggesting that total turbinectomy may reduce the stimulation of cold receptors by inspired air. Nasal heating and humidification efficiencies decreased significantly after both TIT and TMT. All changes were greater in the TIT models than in the TMT models. TIT yields greater increases in nasal airflow but also impairs the nasal air-conditioning capacity to a greater extent than TMT. Radical resection of the turbinates may decrease the surface area stimulated by mucosal cooling. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

Disposable Electronic Cigarettes and Electronic Hookahs: Evaluation of Performance

PubMed Central

Williams, Monique; Ghai, Sanjay

2015-01-01

Introduction: The purpose of this study was to characterize the performance of disposable button-activated and disposable airflow-activated electronic cigarettes (EC) and electronic hookahs (EH). Methods: The airflow rate required to produce aerosol, pressure drop, and the aerosol absorbance at 420nm were measured during smoke-outs of 9 disposable products. Three units of each product were tested in these experiments. Results: The airflow rates required to produce aerosol and the aerosol absorbances were lower for button-activated models (3mL/s; 0.41–0.55 absorbance) than for airflow-activated models (7–17mL/s; 0.48–0.84 absorbance). Pressure drop was also lower across button-activated products (range = 6–12mm H2O) than airflow-activated products (range = 15–67mm H20). For 25 of 27 units tested, airflow did not have to be increased during smoke-out to maintain aerosol production, unlike earlier generation models. Two brands had uniform performance characteristics for all parameters, while 3 had at least 1 product that did not function normally. While button-activated models lasted 200 puffs or less and EH airflow-activated models often lasted 400 puffs, none of the models produced as many puffs as advertised. Puff number was limited by battery life, which was shorter in button-activated models. Conclusion: The performance of disposable products was differentiated mainly by the way the aerosol was produced (button vs airflow-activated) rather than by product type (EC vs EH). Users needed to take harder drags on airflow-activated models. Performance varied within models, and battery life limited the number of puffs. Data suggest quality control in manufacturing varies among brands. PMID:25104117

Comparison between a Single-Channel Nasal Airflow Device and Oximetry for the Diagnosis of Obstructive Sleep Apnea

PubMed Central

Rofail, Lydia Makarie; Wong, Keith K.H.; Unger, Gunnar; Marks, Guy B.; Grunstein, Ronald R.

2010-01-01

Rationale: The most common single channel devices used for obstructive sleep apnea (OSA) screening are nasal airflow and oximetry. No studies have directly compared their role in diagnosing OSA at home. Study Objectives: To prospectively compare the diagnostic utility of home-based nasal airflow and oximetry to attended polysomnography (PSG) and to assess the diagnostic value of adding oximetry to nasal airflow for OSA. Design: Cross-sectional study Setting: Laboratory and home Participants: Sleep clinic patients with suspected OSA. Interventions: All patients had laboratory PSG and 2 sets of 3 consecutive nights on each device; nasal airflow (Flow Wizard, DiagnoseIT, Australia) and oximetry (Radical Set, Masimo, USA) at home in random order. Results: Ninety-eight of the 105 patients enrolled completed home monitoring. The accuracy of nasal airflow respiratory disturbance index (NF RDI) was not different from oximetry (ODI 3%) for diagnosing OSA (area under the ROC curve (AUC) difference, 0.04; 95% CI of difference −0.05 to 0.12; P = 0.43) over 3 nights of at-home recording. The accuracy of NF RDI was higher after 3 nights compared to one night (AUC difference, 0.05; 95% CI of difference, 0.01 to 0.08; P = 0.04). Addition of oximetry to nasal airflow did not increase the accuracy for predicting OSA compared to nasal airflow alone (P > 0.1). Conclusions: Nasal flow and oximetry have equivalent accuracy for diagnosing OSA in the home setting. Choice of device for home screening of sleep apnea may depend on logistical and service delivery issues. Citation: Makarie Rofail L; Wong KKH; Unger G; Marks GB; Grunstein RR. Comparison between a single-channel nasal airflow device and oximetry for the diagnosis of obstructive sleep apnea. SLEEP 2010;33(8):1106-1114. PMID:20815194

Investigation of nanosecond pulsed dielectric barrier discharge using plate-to-plate electrode with asymmetric dielectric arrangement in airflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qi, Haicheng; School of Physics Science and Technology, Anshan Normal University, Anshan 114005; Fan, Zhihui

Atmospheric pressure dielectric barrier discharge plasma is produced in airflow by applying nanosecond high voltage pulses with peak voltage about 35 kV and rising time about 40 ns on a plate-to-plate electrode arrangement. The effects of airflow rate (0–50 m/s) on the discharge characteristics are investigated under different barrier conditions (the bare anode case and the bare cathode case). For both cases, the breakdown voltage and the time lag increase distinctly and the discharge intensity decreases sharply when the airflow rate increases from 0 to 30 m/s, and then keep almost constant until the airflow rate is further increased to 50 m/s. For the baremore » anode case (the cathode is covered by dielectric plate), the discharge mode transforms gradually from filamentary to diffuse discharge with the increasing airflow rate. While for the bare cathode case, some micro-discharge channels are still excited, though the discharge becomes more diffuse when the airflow rate is higher than 30 m/s. By acquiring the time-resolved images of the discharge, it is proved that it is the primary discharge which becomes diffuse when airflow is introduced and the following two discharges of the same voltage pulse occur principally at the positions where the primary discharge is more intense. And in both cases, the plasma temperatures are reduced, but the degree is different. All the phenomena can be explained mainly by the variation of the space charge distribution when the airflow is introduced into the discharge gap. And it is indicated that the bare anode case has an advantage in obtaining diffuse discharge.« less

Is there any relationship between right and left hand dominance and right and left nasal airflow dominance?

PubMed

Price, A; Eccles, R

2017-10-01

Left- or right-handedness is a common human trait, and it has been previously reported that human nasal airflow dominance correlates with hand dominance. Any relationship between hand dominance and nasal airflow dominance would be unusual. This study aimed to measure nasal airflow and look for any relationship to handedness. The modified Glatzel mirror was used to record the dominant nasal passage at 15-minute intervals over a 6-hour period in 29 healthy participants consisting of 15 left-handers and 14 right-handers. In left-handers, the percentage of time that the left nasal passage was dominant ranged from 0 to 100 per cent. In right-handers, the percentage of time that the right nasal passage was dominant ranged from 4.2 to 95.8 per cent. No correlation between nasal airflow dominance and hand dominance was identified. The results do not support the hypothesis that nasal airflow and handedness are related.

Estimation of the site of wheezes in pulmonary emphysema: airflow simulation study by the use of A 4D lung model.

PubMed

Kitaoka, Hiroko; Cok, Salim

2013-01-01

Adventitious lung sounds in pulmonary emphysema, wheezes, are continuous musical sounds during expiration with 400 Hz or more. The textbook tells that expiratory airflow limitation in emphysema occurs at the peripheral airways and that wheezes are generated there. We have recently proposed a novel hypothesis based on image analysis and theoretical consideration that expiratory airflow limitation in emphysema occurs at the intra-mediastinal airway (trachea, main bronchi, and right lobar bronchi) due to compression by overinflated lungs. We performed expiratory airflow simulation by the use of a 4D finite element lung model, and found periodical vortex release with 300-900 Hz at the end of protrusion of the the tracheal posterior wall. Relationship between the peak frequency of pressure fluctuation and airflow velocity was in agreement with Strahal's law either in normal or emphysematous condition. Contrarily, airflow simulation in a small bronchus (1.5 mm in diameter) indicated no apparent periodic vortex release.

Experimental Research on Optimizing Inlet Airflow of Wet Cooling Towers under Crosswind Conditions

NASA Astrophysics Data System (ADS)

Chen, You Liang; Shi, Yong Feng; Hao, Jian Gang; Chang, Hao; Sun, Feng Zhong

2018-01-01

A new approach of installing air deflectors around tower inlet circumferentially was proposed to optimize the inlet airflow and reduce the adverse effect of crosswinds on the thermal performance of natural draft wet cooling towers (NDWCT). And inlet airflow uniformity coefficient was defined to analyze the uniformity of circumferential inlet airflow quantitatively. Then the effect of air deflectors on the NDWCT performance was investigated experimentally. By contrast between inlet air flow rate and cooling efficiency, it has been found that crosswinds not only decrease the inlet air flow rate, but also reduce the uniformity of inlet airflow, which reduce NDWCT performance jointly. After installing air deflectors, the inlet air flow rate and uniformity coefficient increase, the uniformity of heat and mass transfer increases correspondingly, which improve the cooling performance. In addition, analysis on Lewis factor demonstrates that the inlet airflow optimization has more enhancement of heat transfer than mass transfer, but leads to more water evaporation loss.

Oblique incidence sound absorption of porous materials covered by perforated metal and exposed to tangential airflow

NASA Technical Reports Server (NTRS)

Soderman, Paul T.

1982-01-01

The purpose of this study was to evaluate several acoustic linings that are candidate designs for the Ames 40- by 80-Foot Wind Tunnel test section. The acoustic treatment will be used to reduce wall reflections from aircraft model noise sources. The goal is not simply to attenuate sound propagating down the duct, but rather to create a semi-anechoic space in a windy environment by absorbing at least 80% of the incident acoustic energy over a wide frequency range, if possible.

Dynamic response of a Mach 2.5 axisymmetric inlet and turbojet engine with a poppet-value controlled inlet stability bypass system when subjected to internal and external airflow transients

NASA Technical Reports Server (NTRS)

Sanders, B. W.

1980-01-01

The throat of a Mach 2.5 inlet that was attached to a turbojet engine was fitted with a poppet-valve-controlled stability bypass system that was designed to provide a large, stable airflow range. Propulsion system response and stability bypass performance were determined for several transient airflow disturbances, both internal and external. Internal airflow disturbances included reductions in overboard bypass airflow, power lever angle, and primary-nozzle area as well as compressor stall. For reference, data are also included for a conventional, fixed-exit bleed system. The poppet valves greatly increased inlet stability and had no adverse effects on propulsion system performance. Limited unstarted-inlet bleed performance data are presented.

Measurement of the resistivity of porous materials with an alternating air-flow method.

PubMed

Dragonetti, Raffaele; Ianniello, Carmine; Romano, Rosario A

2011-02-01

Air-flow resistivity is a main parameter governing the acoustic behavior of porous materials for sound absorption. The international standard ISO 9053 specifies two different methods to measure the air-flow resistivity, namely a steady-state air-flow method and an alternating air-flow method. The latter is realized by the measurement of the sound pressure at 2 Hz in a small rigid volume closed partially by the test sample. This cavity is excited with a known volume-velocity sound source implemented often with a motor-driven piston oscillating with prescribed area and displacement magnitude. Measurements at 2 Hz require special instrumentation and care. The authors suggest an alternating air-flow method based on the ratio of sound pressures measured at frequencies higher than 2 Hz inside two cavities coupled through a conventional loudspeaker. The basic method showed that the imaginary part of the sound pressure ratio is useful for the evaluation of the air-flow resistance. Criteria are discussed about the choice of a frequency range suitable to perform simplified calculations with respect to the basic method. These criteria depend on the sample thickness, its nonacoustic parameters, and the measurement apparatus as well. The proposed measurement method was tested successfully with various types of acoustic materials.

Development of an Ultrasonic Airflow Measurement Device for Ducted Air

PubMed Central

Raine, Andrew B.; Aslam, Nauman; Underwood, Christopher P.; Danaher, Sean

2015-01-01

In this study, an in-duct ultrasonic airflow measurement device has been designed, developed and tested. The airflow measurement results for a small range of airflow velocities and temperatures show that the accuracy was better than 3.5% root mean square (RMS) when it was tested within a round or square duct compared to the in-line Venturi tube airflow meter used for reference. This proof of concept device has provided evidence that with further development it could be a low-cost alternative to pressure differential devices such as the orifice plate airflow meter for monitoring energy efficiency performance and reliability of ventilation systems. The design uses a number of techniques and design choices to provide solutions to lower the implementation cost of the device compared to traditional airflow meters. The design choices that were found to work well are the single sided transducer arrangement for a “V” shaped reflective path and the use of square wave transmitter pulses ending with the necessary 180° phase changed pulse train to suppress transducer ringing. The device is also designed so that it does not have to rely on high-speed analogue to digital converters (ADC) and intensive digital signal processing, so could be implemented using voltage comparators and low-cost microcontrollers. PMID:25954952

Mild Airflow Limitation during N2 Sleep Increases K-complex Frequency and Slows Electroencephalographic Activity

PubMed Central

Nguyen, Chinh D.; Wellman, Andrew; Jordan, Amy S.; Eckert, Danny J.

2016-01-01

Study Objectives: To determine the effects of mild airflow limitation on K-complex frequency and morphology and electroencephalogram (EEG) spectral power. Methods: Transient reductions in continuous positive airway pressure (CPAP) during stable N2 sleep were performed to induce mild airflow limitation in 20 patients with obstructive sleep apnea (OSA) and 10 healthy controls aged 44 ± 13 y. EEG at C3 and airflow were measured in 1-min windows to quantify K-complex properties and EEG spectral power immediately before and during transient reductions in CPAP. The frequency and morphology (amplitude and latency of P200, N550 and N900 components) of K-complexes and EEG spectral power were compared between conditions. Results: During mild airflow limitation (18% reduction in peak inspiratory airflow from baseline, 0.38 ± 0.11 versus 0.31 ± 0.1 L/sec) insufficient to cause American Academy of Sleep Medicine-defined cortical arousal, K-complex frequency (9.5 ± 4.5 versus 13.7 ± 6.4 per min, P < 0.01), N550 amplitude (25 ± 3 versus 27 ± 3 μV, P < 0.01) and EEG spectral power (delta: 147 ± 48 versus 230 ± 99 μV2, P < 0.01 and theta bands: 31 ± 14 versus 34 ± 13 μV2, P < 0.01) significantly increased whereas beta band power decreased (14 ± 5 versus 11 ± 4 μV2, P < 0.01) compared to the preceding non flow-limited period on CPAP. K-complex frequency, morphology, and timing did not differ between patients and controls. Conclusion: Mild airflow limitation increases K-complex frequency, N550 amplitude, and spectral power of delta and theta bands. In addition to providing mechanistic insight into the role of mild airflow limitation on K-complex characteristics and EEG activity, these findings may have important implications for respiratory conditions in which airflow limitation during sleep is common (e.g., snoring and OSA). Citation: Nguyen CD, Wellman A, Jordan AS, Eckert DJ. Mild airflow limitation during N2 sleep increases k-complex frequency and slows electroencephalographic activity. SLEEP 2016;39(3):541–550. PMID:26612389

Pitot-tube flowmeter for quantification of airflow during sleep.

PubMed

Kirkness, J P; Verma, M; McGinley, B M; Erlacher, M; Schwartz, A R; Smith, P L; Wheatley, J R; Patil, S P; Amis, T C; Schneider, H

2011-02-01

The gold-standard pneumotachograph is not routinely used to quantify airflow during overnight polysomnography due to the size, weight, bulkiness and discomfort of the equipment that must be worn. To overcome these deficiencies that have precluded the use of a pneumotachograph in routine sleep studies, our group developed a lightweight, low dead space 'pitot flowmeter' (based on pitot-tube principle) for use during sleep. We aimed to examine the characteristics and validate the flowmeter for quantifying airflow and detecting hypopneas during polysomnography by performing a head-to-head comparison with a pneumotachograph. Four experimental paradigms were utilized to determine the technical performance characteristics and the clinical usefulness of the pitot flowmeter in a head-to-head comparison with a pneumotachograph. In each study (1-4), the pitot flowmeter was connected in series with a pneumotachograph under either static flow (flow generator inline or on a face model) or dynamic flow (subject breathing via a polyester face model or on a nasal mask) conditions. The technical characteristics of the pitot flowmeter showed that, (1) the airflow resistance ranged from 0.065 ± 0.002 to 0.279 ± 0.004 cm H(2)O L(-1) s(-1) over the airflow rates of 10 to 50 L min(-1). (2) On the polyester face model there was a linear relationship between airflow as measured by the pitot flowmeter output voltage and the calibrated pneumotachograph signal a (β(1) = 1.08 V L(-1) s(-1); β(0) = 2.45 V). The clinically relevant performance characteristics (hypopnea detection) showed that (3) when the pitot flowmeter was connected via a mask to the human face model, both the sensitivity and specificity for detecting a 50% decrease in peak-to-peak airflow amplitude was 99.2%. When tested in sleeping human subjects, (4) the pitot flowmeter signal displayed 94.5% sensitivity and 91.5% specificity for the detection of 50% peak-to-peak reductions in pneumotachograph-measured airflow. Our data validate the pitot flowmeter for quantification of airflow and detecting breathing reduction during polysomnographic sleep studies. We speculate that quantifying airflow during sleep can differentiate phenotypic traits related to sleep disordered breathing.

Separate and combined effects of airflow and rehydration during exercise in the heat.

PubMed

Mora-Rodriguez, Ricardo; Del Coso, Juan; Aguado-Jimenez, Roberto; Estevez, Emma

2007-10-01

To determine whether airflow is required to obtain the beneficial effects of rehydration (thermoregulatory and cardiovascular) during exercise in dry heat. Ten moderately trained (VO2max = 55 +/- 8 mL.kg(-1).min(-1)) heat acclimated males pedaled for 60 min at 60% VO2max in a hot-dry environment (36 +/- 1 degrees C; 29 +/- 2% relative humidity) on four different occasions: 1) without rehydration or forced airflow (control trial; CON); 2) rehydrating 100% of sweat losses by ingestion of a 6% carbohydrate-electrolyte solution (rehydration trial; REH); 3) receiving airflow at a velocity of 2.55 m.s(-1) (wind trial; WIND); and 4) combining airflow and rehydration (W + R). Without airflow, rehydration alone (REH) did not lower rectal temperature below CON (39.0 +/- 0.1 vs 39.1 +/- 0.1 degrees C at 60 min; respectively). However, with airflow, rehydration reduced final rectal temperature (38.8 +/- 0.1 vs 38.5 +/- 0.1 degrees C; P < 0.05; WIND vs W + R). In the trials with wind (WIND and W + R), skin temperature was reduced by about 0.6 degrees C (P < 0.05), and heart rate drift was prevented. In the trials with rehydration (REH and W + R trials), cardiac output (CO2-rebreathing technique) was maintained higher than CON (16.5 +/- 0.4 and 17.0 +/- 0.7 vs 15.4 +/- 0.4 L.min(-1), respectively; P < 0.05). When exercising in a hot-dry environment, airflow is required for rehydration to improve thermoregulation and cardiovascular function.

Airflow Measurement of the Car HVAC Unit Using Hot-wire Anemometry

NASA Astrophysics Data System (ADS)

Fojtlín, Miloš; Planka, Michal; Fišer, Jan; Pokorný, Jan; Jícha, Miroslav

2016-03-01

Thermal environment in a vehicular cabin significantly influence drivers' fatigue and passengers' thermal comfort. This environment is traditionally managed by HVAC cabin system that distributes air and modifies its properties. In order to simulate cabin thermal behaviour, amount of the air led through car vents must be determined. The aim of this study was to develop methodology to measure airflow from the vents, and consequently calculate corresponding air distribution coefficients. Three climatic cases were selected to match European winter, summer, and spring / fall conditions. Experiments were conducted on a test vehicle in a climatic chamber. The car HVAC system was set to automatic control mode, and the measurements were executed after the system stabilisation—each case was independently measured three times. To be able to evaluate precision of the method, the airflow was determined at the system inlet (HVAC suction) and outlet (each vent), and the total airflow values were compared. The airflow was calculated by determining a mean value of the air velocity multiplied by an area of inlet / outlet cross-section. Hot-wire anemometry was involved to measure the air velocity. Regarding the summer case, total airflow entering the cabin was around 57 l s-1 with 60 % of the air entering the cabin through dashboard vents; no air was supplied to the feet compartment. The remaining cases had the same total airflow of around 42 l s-1, and the air distribution was focused mainly on feet and windows. The inlet and outlet airflow values show a good match with a maximum mass differential of 8.3 %.

Resistance to forced airflow through layers of composting organic material.

PubMed

Teixeira, Denis Leocádio; de Matos, Antonio Teixeira; Melo, Evandro de Castro

2015-02-01

The objective of this study was to adjust equations to estimate the static pressure gradient of airflow through layers of organic residues submitted to two stages of biochemical degradation, and to evaluate the static pressure drop of airflow thought the material layer. Measurements of static pressure drop in the layers of sugarcane bagasse and coffee husks mixed with poultry litter on day 0 and after 30 days of composting were performed using a prototype with specific airflow rates ranging from 0.02 to 0.13 m(3) s(-1) m(-2). Static pressure gradient and specific airflow rate data were properly fit to the Shedd, Hukill & Ives and Ergun models, which may be used to predict the static pressure gradient of air to be blown through the organic residue layers. However, the Shedd model was that which best represented the phenomenon studied. The static pressure drop of airflow increased as a power of the material layer thickness and showed tendency for decreasing with the biochemical degradation time of the organic material. Copyright © 2014 Elsevier Ltd. All rights reserved.

EC79-11481

NASA Image and Video Library

1979-08-20

A chase plane view of the tufts on the KC-135 winglet. The use of tufts in flight research dates back to the early days of the NACA, and remains an effective means of observing airflow even today. In this procedure, rows of strings are attached to an airplane's surface, with one end of each string taped to the airplane and the other end free to swing about in the airflow. The movements of the tufts are photographed by on-board cameras or a chase plane. If the tufts are arrayed in neat rows, as seen here, then the airflow is smooth over the airplane's surface. If, however, they are moving about violently, it suggests turbulent airflow. Such motions may indicate high drag, flow separation (such as in a stall), or buffeting. In some cases, tufts will actually point forward, indicating the airflow has reversed direction.

Mild Airflow Limitation during N2 Sleep Increases K-complex Frequency and Slows Electroencephalographic Activity.

PubMed

Nguyen, Chinh D; Wellman, Andrew; Jordan, Amy S; Eckert, Danny J

2016-03-01

To determine the effects of mild airflow limitation on K-complex frequency and morphology and electroencephalogram (EEG) spectral power. Transient reductions in continuous positive airway pressure (CPAP) during stable N2 sleep were performed to induce mild airflow limitation in 20 patients with obstructive sleep apnea (OSA) and 10 healthy controls aged 44 ± 13 y. EEG at C3 and airflow were measured in 1-min windows to quantify K-complex properties and EEG spectral power immediately before and during transient reductions in CPAP. The frequency and morphology (amplitude and latency of P200, N550 and N900 components) of K-complexes and EEG spectral power were compared between conditions. During mild airflow limitation (18% reduction in peak inspiratory airflow from baseline, 0.38 ± 0.11 versus 0.31 ± 0.1 L/sec) insufficient to cause American Academy of Sleep Medicine-defined cortical arousal, K-complex frequency (9.5 ± 4.5 versus 13.7 ± 6.4 per min, P < 0.01), N550 amplitude (25 ± 3 versus 27 ± 3 μV, P < 0.01) and EEG spectral power (delta: 147 ± 48 versus 230 ± 99 μV(2), P < 0.01 and theta bands: 31 ± 14 versus 34 ± 13 μV(2), P < 0.01) significantly increased whereas beta band power decreased (14 ± 5 versus 11 ± 4 μV(2), P < 0.01) compared to the preceding non flow-limited period on CPAP. K-complex frequency, morphology, and timing did not differ between patients and controls. Mild airflow limitation increases K-complex frequency, N550 amplitude, and spectral power of delta and theta bands. In addition to providing mechanistic insight into the role of mild airflow limitation on K-complex characteristics and EEG activity, these findings may have important implications for respiratory conditions in which airflow limitation during sleep is common (e.g., snoring and OSA). © 2016 Associated Professional Sleep Societies, LLC.

Effects of airflow on body temperatures and sleep stages in a warm humid climate

NASA Astrophysics Data System (ADS)

Tsuzuki, Kazuyo; Okamoto-Mizuno, Kazue; Mizuno, Koh; Iwaki, Tatsuya

2008-03-01

Airflow is an effective way to increase heat loss—an ongoing process during sleep and wakefulness in daily life. However, it is unclear whether airflow stimulates cutaneous sensation and disturbs sleep or reduces the heat load and facilitates sleep. In this study, 17 male subjects wearing short pyjamas slept on a bed with a cotton blanket under two of the following conditions: (1) air temperature (Ta) 26°C, relative humidity (RH) 50%, and air velocity (V) 0.2 m s-1; (2) Ta 32°C, RH 80%, V 1.7 m s-1; (3) Ta 32°C; RH 80%, V 0.2 m s-1 (hereafter referred to as 26/50, 32/80 with airflow, and 32/80 with still air, respectively). Electroencephalograms, electrooculograms, and mental electromyograms were obtained for all subjects. Rectal (Tre) and skin (Ts) temperatures were recorded continuously during the sleep session, and body-mass was measured before and after the sleep session. No significant differences were observed in the duration of sleep stages between subjects under the 26/50 and 32/80 with airflow conditions; however, the total duration of wakefulness decreased significantly in subjects under the 32/80 with airflow condition compared to that in subjects under the 32/80 with still air condition ( P < 0.05). Tre, Tsk, Ts, and body-mass loss under the 32/80 with airflow condition were significantly higher compared to those under the 26/50 condition, and significantly lower than those under the 32/80 with still air condition ( P < 0.05). An alleviated heat load due to increased airflow was considered to exist between the 32/80 with still air and the 26/50 conditions. Airflow reduces the duration of wakefulness by decreasing Tre, Tsk, Ts, and body-mass loss in a warm humid condition.

Experimental investigation into the interaction between the human body and room airflow and its effect on thermal comfort under stratum ventilation.

PubMed

Cheng, Y; Lin, Z

2016-04-01

Room occupants' comfort and health are affected by the airflow. Nevertheless, they themselves also play an important role in indoor air distribution. This study investigated the interaction between the human body and room airflow under stratum ventilation. Simplified thermal manikin was employed to effectively resemble the human body as a flow obstacle and/or free convective heat source. Unheated and heated manikins were designed to fully evaluate the impact of the manikin at various airflow rates. Additionally, subjective human tests were conducted to evaluate thermal comfort for the occupants in two rows. The findings show that the manikin formed a local blockage effect, but the supply airflow could flow over it. With the body heat from the manikin, the air jet penetrated farther compared with that for the unheated manikin. The temperature downstream of the manikin was also higher because of the convective effect. Elevating the supply airflow rate from 7 to 15 air changes per hour varied the downstream airflow pattern dramatically, from an uprising flow induced by body heat to a jet-dominated flow. Subjective assessments indicated that stratum ventilation provided thermal comfort for the occupants in both rows. Therefore, stratum ventilation could be applied in rooms with occupants in multiple rows. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Measurement of Turbine Engine Transient Airflow in Ground Test Facilities

DTIC Science & Technology

1980-08-01

REPORT NUMBER 12 GOVT ACCESSION NO. A E D C - T R - 8 0 - 2 1 L 6. T I T L E (aqd Subl l l |e ) MEASUREMENT OF TURBINE ENGINE TRANSIENT AIRFLOW IN...21 ILLUSTRATIONS Figure !. Direct-Connect Turbine Engine Test Cell Installation...26 3. Turbine Engine Transient Airflow Simulator (TETAS) . . . . . . . . . . . . . . . . . . . . . . . . . 27 4

Airflow accelerates bovine and human articular cartilage drying and chondrocyte death.

PubMed

Paterson, S I; Amin, A K; Hall, A C

2015-02-01

Exposure of articular cartilage to static air results in changes to the extracellular matrix (ECM) and stimulates chondrocyte death, which may cause joint degeneration. However during open orthopaedic surgery, cartilage is often exposed to laminar airflow, which may exacerbate these damaging effects. We compared drying in static and moving air in terms of cartilage appearance, hydration and chondrocyte viability, and tested the ability of saline-saturated gauze to limit the detrimental effects of air exposure. Articular cartilage from bovine metatarsophalangeal joints (N = 50) and human femoral heads (N = 6) was exposed for 90 min to (1) static air (2) airflow (up to 0.34 m/s), or (3) airflow (0.18 m/s), covered with gauze. Following air exposure, cartilage was also rehydrated (0.9% saline; 120 min) to determine the reversibility of drying effects. The influence of airflow was assessed by studying macroscopic appearance, and quantifying superficial zone (SZ) chondrocyte viability and cartilage hydration. Airflow caused advanced changes to cartilage appearance, accelerated chondrocyte death, and increased dehydration compared to static air. These effects were prevented if cartilage was covered by saline-saturated gauze. Cartilage rehydration reversed macroscopic changes associated with drying but the chondrocyte death was not altered. Chondrocytes at the cut edge of cartilage were more sensitive to drying compared to cells distant from the edge. Airflow significantly increased articular cartilage dehydration and chondrocyte death compared to static air. As laminar airflow is routinely utilised in operating theatres, it is essential that articular cartilage is kept wet via irrigation or by covering with saline-saturated gauze to prevent chondrocyte death. Copyright © 2014 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

KC-135A in flight - closeup of winglet with attached tufts

NASA Technical Reports Server (NTRS)

1979-01-01

A chase plane view of the tufts on the KC-135 winglet. The use of tufts in flight research dates back to the early days of the NACA, and remains an effective means of observing airflow even today. In this procedure, rows of strings are attached to an airplane's surface, with one end of each string taped to the airplane and the other end free to swing about in the airflow. The movements of the tufts are photographed by on-board cameras or a chase plane. If the tufts are arrayed in neat rows, as seen here, then the airflow is smooth over the airplane's surface. If, however, they are moving about violently, it suggests turbulent airflow. Such motions may indicate high drag, flow separation (such as in a stall), or buffeting. In some cases, tufts will actually point forward, indicating the airflow has reversed direction.

Preliminary investigation on the effects of primary airflow to coal particle distribution in coal-fired boilers

NASA Astrophysics Data System (ADS)

Noor, N. A. W. Mohd; Hassan, H.; Hashim, M. F.; Hasini, H.; Munisamy, K. M.

2017-04-01

This paper presents an investigation on the effects of primary airflow to coal fineness in coal-fired boilers. In coal fired power plant, coal is pulverized in a pulverizer, and it is then transferred to boiler for combustion. Coal need to be ground to its desired size to obtain maximum combustion efficiency. Coarse coal particle size may lead to many performance problems such as formation of clinker. In this study, the effects of primary airflow to coal particles size and coal flow distribution were investigated by using isokinetic coal sampling and computational fluid dynamic (CFD) modelling. Four different primary airflows were tested and the effects to resulting coal fineness were recorded. Results show that the optimum coal fineness distribution is obtained at design primary airflow. Any reduction or increase of air flow rate results in undesirable coal fineness distribution.

Flow Straightener for a Rotating-Drum Liquid Separator

NASA Technical Reports Server (NTRS)

O'Coin, James R.; Converse, David G.; Rethke, Donald W.

2004-01-01

A flow straightener has been incorporated into a rotary liquid separator that originally comprised an inlet tube, a shroud plate, an impeller, an inner drum, an outer drum, a housing, a pitot tube, and a hollow shaft motor. As a consequence of the original geometry of the impeller, shroud, inner drum, and hollow shaft, swirl was created in the airflow inside the hollow shaft during operation. The swirl speed was large enough to cause a significant pressure drop. The flow straightener consists of vanes on the back side of the shroud plate. These vanes compartmentalize the inside of the inner drum in such a way as to break up the flow path and thereby stop the air from swirling; as a result, the air enters the hollow shaft with a predominantly axial velocity instead of a swirl. Tests of the rotary liquid separator at an airflow rate of 10 cu ft/min (0.0047 cu m/s) revealed that the dynamic pressure drop was 8 in. of water (approx.=2 kPa) in the absence of the flow straightener and was reduced to 1 in. of water (approx.=0.25 kPa) in the presence of the flow straightener.

Numerical Simulation of the Self-Oscillations of the Vocal Folds and of the Resulting Acoustic Phenomena in the Vocal Tract

NASA Astrophysics Data System (ADS)

Švancara, P.; Horáček, J.; Švec, J. G.

The study presents a three-dimensional (3D) finite element (FE) model of the flow-induced self-oscillation of the human vocal folds in interaction with acoustics of simplified vocal tract models. The 3D vocal tract models of the acoustic spaces shaped for simulation of phonation of Czech vowels [a:], [i:] and [u:] were created by converting the data from the magnetic resonance images (MRI). For modelling of the fluid-structure interaction, explicit coupling scheme with separated solvers for fluid and structure domain was utilized. The FE model comprises vocal folds pretension before starting phonation, large deformations of the vocal fold tissue, vocal-fold collisions, fluid-structure interaction, morphing the fluid mesh according to the vocal-fold motion (Arbitrary Lagrangian-Eulerian approach), unsteady viscous compressible airflow described by the Navier-Stokes equations and airflow separation. The developed FE model enables to study the relationship between flow-induced vibrations of the vocal folds and acoustic wave propagation in the vocal tract and can also be used to simulate for example pathological changes in the vocal fold tissue and their influence on the voice production.

Data Visualization of Invisible Airflow Hazards During Helicopter Takeoff and Landing Operations

NASA Technical Reports Server (NTRS)

Aragon, Cecilia R.

2004-01-01

Many aircraft accidents each year are caused by encounters with unseen airflow hazards near the ground such as vortices, downdrafts, wind shear, microbursts, or other turbulence. While such hazards frequently pose problems to fixed-wing airplanes, they are especially dangerous to helicopters, which often have to operate in confined spaces and under operationally stressful conditions. We are developing flight-deck visualizations of airflow hazards during helicopter takeoff and landing operations, and are evaluating their effectiveness with usability studies. Our hope is.that this work will lead to the production of an airflow hazard detection system for pilots that will save lives.

Distributed porous throat stability bypass to increase the stable airflow range of a Mach 2.5 inlet with 60 percent internal contraction

NASA Technical Reports Server (NTRS)

Shaw, R. J.; Mitchell, G. A.; Sanders, B. W.

1974-01-01

The results of an experimental investigation to increase the stable airflow operating range of a supersonic, mixed-compression inlet with 60-percent internal contraction are presented. Various distributed-porous, throat stability-bypass entrance configurations were tested. In terms of diffuser-exit corrected airflow, a large inlet stable airflow range of about 25 percent was obtained with the optimum configuration if a constant pressure was maintained in the by-pass plenum. The location of the centerbody bleed region had a decided effect on the overall inlet performance. Limited unstart angle-of-attack data are presented.

Using Computational Fluid Dynamics to examine airflow characteristics in Empty Nose Syndrome

NASA Astrophysics Data System (ADS)

Flint, Tim; Esmaily-Moghadam, Mahdi; Thamboo, Andrew; Velasquez, Nathalia; Nayak, Jayakar V.; Sellier, Mathieu; Moin, Parviz

2016-11-01

The enigmatic disorder, empty nose syndrome (ENS), presents with a complex subjective symptom profile despite objectively patent nasal airways, and recent reports suggest that surgical augmentation of the nasal airway can improve quality of life and ENS-related complaints. In this study, computational fluid dynamics (CFD) was performed both prior to, and following, inferior turbinate augmentation to model the resultant changes in airflow patterns and better understand the pathophysiology of ENS. An ENS patient with marked reduction in ENS symptoms following turbinate augmentation was identified, and pre- and post-operative CT imaging was collected. A Finite element framework with the variational multiscale method (Esmaily-Moghadam, Comput. Methods Appl. Mech. Engrg. 2015) was used to compute the airflow, temperature, and moisture transport through the nasal cavity. Comparison of the CFD results following corrective surgery showed higher levels of airflow turbulence. Augmentation produced 50%, 25%, and 25% increases in root mean square pressure, wall shear stress, and heat flux respectively. These results provide insight into the changes in nasal airflow characteristics attainable through surgical augmentation, and by extension, how nasal airflow patterns may be distorted in the 'overly patent' airway of ENS patients. Supported by Stanford University CTR and Fulbright New Zealand.

Nocturnal Near-Surface Temperature, but not Flow Dynamics, can be Predicted by Microtopography in a Mid-Range Mountain Valley

NASA Astrophysics Data System (ADS)

Pfister, Lena; Sigmund, Armin; Olesch, Johannes; Thomas, Christoph K.

2017-11-01

We investigate nocturnal flow dynamics and temperature behaviour near the surface of a 170-m long gentle slope in a mid-range mountain valley. In contrast to many existing studies focusing on locations with significant topographic variations, gentle slopes cover a greater spatial extent of the Earth's surface. Air temperatures were measured using the high-resolution distributed-temperature-sensing method within a two-dimensional fibre-optic array in the lowest metre above the surface. The main objectives are to characterize the spatio-temporal patterns in the near-surface temperature and flow dynamics, and quantify their responses to the microtopography and land cover. For the duration of the experiment, including even clear-sky nights with weak winds and strong radiative forcing, the classical cold-air drainage predicted by theory could not be detected. In contrast, we show that the airflow for the two dominant flow modes originates non-locally. The most abundant flow mode is characterized by vertically-decoupled layers featuring a near-surface flow perpendicular to the slope and strong stable stratification, which contradicts the expectation of a gravity-driven downslope flow of locally produced cold air. Differences in microtopography and land cover clearly affect spatio-temporal temperature perturbations. The second most abundant flow mode is characterized by strong mixing, leading to vertical coupling with airflow directed down the local slope. Here variations of microtopography and land cover lead to negligible near-surface temperature perturbations. We conclude that spatio-temporal temperature perturbations, but not flow dynamics, can be predicted by microtopography, which complicates the prediction of advective-heat components and the existence and dynamics of cold-air pools in gently sloped terrain in the absence of observations.

CFD Ventilation Study for the Human Powered Centrifuge at the International Space Station

NASA Technical Reports Server (NTRS)

Son, Chang H.

2011-01-01

The Human Powered Centrifuge (HPC) is a hyper gravity facility that will be installed on board the International Space Station (ISS) to enable crew exercises under the artificial gravity conditions. The HPC equipment includes a bicycle for long-term exercises of a crewmember that provides power for rotation of HPC at a speed of 30 rpm. The crewmember exercising vigorously on the centrifuge generates the amount of carbon dioxide of several times higher than a crewmember in ordinary conditions. The goal of the study is to analyze the airflow and carbon dioxide distribution within Pressurized Multipurpose Module (PMM) cabin. The 3D computational model included PMM cabin. The full unsteady formulation was used for airflow and CO2 transport modeling with the so-called sliding mesh concept is considered in the rotating reference frame while the rest of the cabin volume is considered in the stationary reference frame. The localized effects of carbon dioxide dispersion are examined. Strong influence of the rotating HPC equipment on the CO2 distribution is detected and discussed.

Aerodynamic tricks for pitching oscillation and visual stabilization in a hovering bird

NASA Astrophysics Data System (ADS)

Su, Jian-Yuan; Ting, Shang-Chieh; Yang, Jing-Tang

2010-11-01

We experimentally investigate how small birds attain a stabilized vision and body posture during hovering. Wing-beats of finches and passerines executing asymmetrical hovering provide lift merely during the downstroke. The downstroke lift is significantly greater than the bird weight, thereby causing a pitch-up swing of the bird body. A hovering bird skillfully and unceasingly tunes the position and orientation of lift force to stabilize its vision, so that the eye displacement is approximately one-tenth less than the tail, causing an illusion that the bird body is rotating about the eye. The hovering birds also spread and fold periodically their tail with an evident phase relationship with respect to the beating wings. We found that hovering birds use their tail to intercept the strong downward air-flow induced by the downstroking wings, and sophisticatedly spread their tail upon the arrival of the downward air-flow, rendering a pitch-up moment that effectively counteracts the pitch-down body rotation. Hence during hovering the bird essentially undergoes a dynamically-stable pitching oscillation, and concurrently attains a stabilized vision.

Cleanrooms and tissue banking how happy I could be with either GMP or GTP?

PubMed

Klykens, J; Pirnay, J-P; Verbeken, G; Giet, O; Baudoux, E; Jashari, R; Vanderkelen, A; Ectors, N

2013-12-01

The regulatory framework of tissue banking introduces a number of requirements for monitoring cleanrooms for processing tissue or cell grafts. Although a number of requirements were clearly defined, some requirements are open for interpretation. This study aims to contribute to the interpretation of GMP or GTP guidelines for tissue banking. Based on the experience of the participating centers, the results of the monitoring program were evaluated to determine the feasibility of a cleanroom in tissue banking and the monitoring program. Also the microbial efficacy of a laminar airflow cabinet and an incubator in a cleanroom environment was evaluated. This study indicated that a monitoring program of a cleanroom at rest in combination with (final) product testing is a feasible approach. Although no statistical significance (0.90 < p < 0.95) was found there is a strong indication that a Grade D environment is not the ideal background environment for a Grade A obtained through a laminar airflow cabinet. The microbial contamination of an incubator in a cleanroom is limited but requires closed containers for tissue and cell products.

Observations of interference between portable particle counters and NOx monitors

NASA Astrophysics Data System (ADS)

Bereznicki, Sarah D.; Kamal, Ali

2013-08-01

Studies in environmental exposure science have developed a preference for smaller devices that can be easily co-located without need for gas standards, such as those instruments utilized in the Near-road Exposures and Effects from Urban Air Pollutants Study (NEXUS). One observation from NEXUS was the potential for instrument interference from alcohol-based particle counters on photometric-based nitrogen oxide (NOx) monitors. This article reports the findings from laboratory tests replicating enclosed-shelter monitoring configurations and operation cycles for a common photometric-based NOx monitor and a widely used alcohol-based particle counter. These tests monitored the NOx response while the particle counter sampling interval and ambient airflow rate were varied to (1) confirm that proximity between the instruments induced interferences, (2) identify any dependencies in NOx monitor recovery on ambient airflow, and (3) determine the time needed for the NOx monitor to recover to pre-interference levels under different atmospheric conditions. During particle counter operations, NOx concentrations responded instantaneously with a several-fold jump above the measurement baseline. When the particle counter was operated for more than 10 min, this interference period also showed a marked decline in the NOx baseline. The overall recovery time of the NOx monitor depended less on the time of particle counter operation, and more on the speed of ambient airflow. If photometric-based NOx monitors need to be operated alongside alcohol-based particle counters, mechanisms must be employed to exhaust alcohol-based vapors from enclosed monitoring environments. Given the strong evidence for interference, however, it is recommended these devices not be operated within close proximity to one another.

The association between chronic airflow obstruction and poverty in 12 sites of the multinational BOLD study.

PubMed

Townend, John; Minelli, Cosetta; Mortimer, Kevin; Obaseki, Daniel O; Al Ghobain, Mohammed; Cherkaski, Hamid; Denguezli, Myriam; Gunesekera, Kirthi; Hafizi, Hasan; Koul, Parvaiz A; Loh, Li C; Nejjari, Chakib; Patel, Jaymini; Sooronbayev, Talant; Buist, Sonia A; Burney, Peter G J

2017-06-01

Poverty is strongly associated with mortality from COPD, but little is known of its relation to airflow obstruction.In a cross-sectional study of adults aged ≥40 years from 12 sites (N=9255), participating in the Burden of Obstructive Lung Disease (BOLD) study, poverty was evaluated using a wealth score (0-10) based on household assets. Obstruction, measured as forced expiratory volume in 1 s (FEV 1 )/forced vital capacity (FVC) (%) after administration of 200 μg salbutamol, and prevalence of FEV 1 /FVC

The role of endotoxin in grain dust-induced lung disease.

PubMed

Schwartz, D A; Thorne, P S; Yagla, S J; Burmeister, L F; Olenchock, S A; Watt, J L; Quinn, T J

1995-08-01

To identify the role of endotoxin in grain dust-induced lung disease, we conducted a population-based, cross-sectional investigation among grain handlers and postal workers. The study subjects were selected by randomly sampling all grain facilities and post offices within 100 miles of Iowa City. Our study population consisted of 410 grain workers and 201 postal workers. Grain workers were found to be exposed to higher concentrations of airborne dust (p = 0.0001) and endotoxin (p = 0.0001) when compared with postal workers. Grain workers had a significantly higher prevalence of work-related (cough, phlegm, wheezing, chest tightness, and dyspnea) and chronic (usual cough or phlegm production) respiratory symptoms than postal workers. Moreover, after controlling for age, gender, and cigarette smoking status, work-related respiratory symptoms were strongly associated with the concentration of endotoxin in the bioaerosol in the work setting. The concentration of total dust in the bioaerosol was marginally related to these respiratory problems. After controlling for age, gender, and cigarette smoking status, grain workers were found to have reduced spirometric measures of airflow (FEV1, FEV1/FVC, and FEF25-75) and enhanced airway reactivity to inhaled histamine when compared with postal workers. Although the total dust concentration in the work environment appeared to have little effect on these measures of airflow obstruction, higher concentrations of endotoxin in the bioaerosol were associated with diminished measures of airflow and enhanced bronchial reactivity. Our results indicate that the concentration of endotoxin in the bioaerosol may be particularly important in the development of grain dust-induced lung disease.

FEV1/FVC and FEV1 for the assessment of chronic airflow obstruction in prevalence studies: do prediction equations need revision?

PubMed

Roche, Nicolas; Dalmay, François; Perez, Thierry; Kuntz, Claude; Vergnenègre, Alain; Neukirch, Françoise; Giordanella, Jean-Pierre; Huchon, Gérard

2008-11-01

Little is known on the long-term validity of reference equations used in the calculation of FEV(1) and FEV(1)/FVC predicted values. This survey assessed the prevalence of chronic airflow obstruction in a population-based sample and how it is influenced by: (i) the definition of airflow obstruction; and (ii) equations used to calculate predicted values. Subjects aged 45 or more were recruited in health prevention centers, performed spirometry and fulfilled a standardized ECRHS-derived questionnaire. Previously diagnosed cases and risk factors were identified. Prevalence of airflow obstruction was calculated using: (i) ATS-GOLD definition (FEV(1)/FVC<0.70); and (ii) ERS definition (FEV(1)/FVC

Magnetic resonance imaging and computational fluid dynamics (CFD) simulations of rabbit nasal airflows for the development of hybrid CFD/PBPK models.

PubMed

Corley, R A; Minard, K R; Kabilan, S; Einstein, D R; Kuprat, A P; Harkema, J R; Kimbell, J S; Gargas, M L; Kinzell, John H

2009-05-01

The percentages of total airflows over the nasal respiratory and olfactory epithelium of female rabbits were calculated from computational fluid dynamics (CFD) simulations of steady-state inhalation. These airflow calculations, along with nasal airway geometry determinations, are critical parameters for hybrid CFD/physiologically based pharmacokinetic models that describe the nasal dosimetry of water-soluble or reactive gases and vapors in rabbits. CFD simulations were based upon three-dimensional computational meshes derived from magnetic resonance images of three adult female New Zealand White (NZW) rabbits. In the anterior portion of the nose, the maxillary turbinates of rabbits are considerably more complex than comparable regions in rats, mice, monkeys, or humans. This leads to a greater surface area to volume ratio in this region and thus the potential for increased extraction of water soluble or reactive gases and vapors in the anterior portion of the nose compared to many other species. Although there was considerable interanimal variability in the fine structures of the nasal turbinates and airflows in the anterior portions of the nose, there was remarkable consistency between rabbits in the percentage of total inspired airflows that reached the ethmoid turbinate region (approximately 50%) that is presumably lined with olfactory epithelium. These latter results (airflows reaching the ethmoid turbinate region) were higher than previous published estimates for the male F344 rat (19%) and human (7%). These differences in regional airflows can have significant implications in interspecies extrapolations of nasal dosimetry.

Mockup Small-Diameter Air Distribution System

DOE Office of Scientific and Technical Information (OSTI.GOV)

A. Poerschke and A. Rudd

2016-05-01

This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to be brought easily within conditioned space via interior partition walls. Centrally locating the air hander unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives an equal amount of airflow, regardless of the duct position on the box. Furthermore, within a reasonable set of length restrictions, each duct continues to receive similar airflow. The design method uses anmore » additive approach to reach the total needed zonal airflow. Once the cubic feet per minute needed to satisfy the thermal load of a zone has been determined, the total number of duct runs to a zone can be calculated by dividing the required airflow by the standard airflow from each duct. The additive approach greatly simplifies the design effort and reduces the potential for duct design mistakes to be made. Measured results indicate that this plenum design can satisfy the heating load. However, the total airflow falls short of satisfying the cooling load in a hypothetical building. Static pressure inside the plenum box of 51.5 Pa limited the total airflow of the attached mini-split heat pump blower, thus limiting the total thermal capacity. Fan energy consumption is kept to 0.16 to 0.22 watt/CFM by using short duct runs and smooth duct material.« less

Analysis of Clinicians' Perceptual Cough Evaluation.

PubMed

Laciuga, Helena; Brandimore, Alexandra E; Troche, Michelle S; Hegland, Karen W

2016-08-01

This study examined the relationships between subjective descriptors and objective airflow measures of cough. We hypothesized that coughs with specific airflow characteristics would share common subjective perceptual descriptions. Thirty clinicians (speech-language pathologists, otolaryngologists, and neurologists) perceptually evaluated ten cough audio samples with specific airflow characteristics determined by peak expiratory flow rate, cough expired volume, cough duration, and number of coughs in the cough epoch. Participants rated coughs by strength, duration, quality, quantity, and overall potential effectiveness for airway protection. Perception of cough strength and effectiveness was determined by the combination of presence of pre-expulsive compression phase, short peak expiratory airflow rate rise time, high peak expiratory flow rates, and high cough volume acceleration. Perception of cough abnormality was defined predominantly by descriptors of breathiness and strain. Breathiness was characteristic for coughs with either absent compression phases and relatively high expiratory airflow rates or coughs with significantly low expired volumes and reduced peak flow rates. In contrast, excessive strain was associated with prolonged compression phases and low expiratory airflow rates or the absence of compression phase with high peak expiratory rates. The study participants reached greatest agreement in distinguishing between single and multiple coughs. Their assessment of cough strength and effectiveness was less consistent. Finally, the least agreement was shown in determining the quality categories. Modifications of cough airflow can influence perceptual cough evaluation outcomes. However, the inconsistency of cough ratings among our participants suggests that a uniform cough rating system is required.

DOE Office of Scientific and Technical Information (OSTI.GOV)

This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to be brought easily within conditioned space via interior partition walls. Centrally locating the air hander unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives an equal amount of airflow, regardless of the duct position on the box. Furthermore, within a reasonable set of length restrictions, each duct continues to receive similar airflow. The design method uses anmore » additive approach to reach the total needed zonal airflow. Once the cubic feet per minute needed to satisfy the thermal load of a zone has been determined, the total number of duct runs to a zone can be calculated by dividing the required airflow by the standard airflow from each duct. The additive approach greatly simplifies the design effort and reduces the potential for duct design mistakes to be made. Measured results indicate that this plenum design can satisfy the heating load. However, the total airflow falls short of satisfying the cooling load in a hypothetical building. Static pressure inside the plenum box of 51.5 Pa limited the total airflow of the attached mini-split heat pump blower, thus limiting the total thermal capacity. Fan energy consumption is kept to 0.16 to 0.22 watt/CFM by using short duct runs and smooth duct material.« less

Whose murk is this?

NASA Astrophysics Data System (ADS)

Samson, P. J.

2010-12-01

The public is painfully aware when the sky turns murky and air quality advisories are posted. They are often less aware if or how these events are associated with particular weather and airflow conditions. In order to give citizens the power to explore their air quality a web site, SharedAir, has been created that lists concentrations of pollutants at various measurement sites around the world and displays the trajectories associated with each day. This site is a first step in raising public literacy on how atmospheric transport affects air quality degradation. SharedAir representation of sulfate concentrations measured in Sacramento, CA on December 6, 2006.

Majority of never-smokers with airflow limitation do not have asthma: the Copenhagen General Population Study.

PubMed

Çolak, Yunus; Afzal, Shoaib; Nordestgaard, Børge G; Lange, Peter

2016-07-01

A substantial proportion of individuals with airflow limitation are never-smokers. However, whether never-smokers with airflow limitation have undiagnosed asthma is unknown. We hypothesised that the majority of never-smokers with respiratory symptoms and airflow limitation but without known asthma have undiagnosed asthma by comparing characteristics and prognosis in never-smokers with airflow limitation and asthma (NS+AFL+A) with never-smokers with airflow limitation but without asthma (NS+AFL-A). Among 94 079 participants aged 20-100 years from the general population, 39 102 (42%) were never-smokers. In this group, 13 719 (35%) reported to have respiratory symptoms of whom 1610 (12%) had airflow limitation. We investigated characteristics and risk of complications (asthma or COPD exacerbations, pneumonias and all-cause mortality) and comorbidities (lung cancer, ischaemic heart disease, myocardial infarction, deep venous thrombosis and PE) during 4.5 years median follow-up. NS+AFL-A compared with NS+AFL+A reported less allergy and respiratory symptoms, and had higher FEV1 and lower levels of eosinophils and IgE in peripheral blood. NS+AFL+A had increased risk of asthma and COPD exacerbations, but not of pneumonias; adjusted HRs in NS+AFL+A compared with NS+AFL-A were 16 (95% CI 3.7 to 73) for asthma exacerbations and 15 (2.8 to 80) for COPD exacerbations. Still, NS+AFL-A had increased risk of COPD exacerbations and pneumonias, but not of asthma exacerbations; adjusted HRs in NS+AFL-A compared with never-smokers without airflow limitation or asthma (NS-AFL-A) were 7.7 (2.8 to 21) for COPD exacerbations and 1.7 (1.3 to 2.3) for pneumonias. Risk of comorbidities or all-cause mortality was not increased in NS+AFL-A or NS+AFL+A compared with NS-AFL-A. Majority of NS+AFL-A do not seem to have undiagnosed asthma and may instead have airflow limitation caused by other risk factors. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

An In Silico Subject-Variability Study of Upper Airway Morphological Influence on the Airflow Regime in a Tracheobronchial Tree

PubMed Central

Chen, Xiaole; Lin, Jiang

2017-01-01

Determining the impact of inter-subject variability on airflow pattern and nanoparticle deposition in the human respiratory system is necessary to generate population-representative models, useful for several biomedical engineering applications. Thus, the overall research objective is to quantitatively correlate geometric parameters and coupled transport characteristics of air, vapor, and nanoparticles. Focusing on identifying morphological parameters that significantly influence airflow field and nanoparticle transport, an experimentally validated computational fluid-particle dynamics (CFPD) model was employed to simulate airflow pattern in three human lung-airway configurations. The numerical results will be used to generate guidelines to construct a representative geometry of the human respiratory system. PMID:29144436

Inlet-engine matching for SCAR including application of a bicone variable geometry inlet

NASA Technical Reports Server (NTRS)

Wasserbauer, J. F.; Gerstenmaier, W. H.

1978-01-01

Airflow characteristics of variable cycle engines (VCE) designed for Mach 2.32 can have transonic airflow requirements as high as 1.6 times the cruise airflow. This is a formidable requirement for conventional, high performance, axisymmetric, translating centerbody mixed compression inlets. An alternate inlet is defined, where the second cone of a two cone center body collapses to the initial cone angle to provide a large off-design airflow capability, and incorporates modest centerbody translation to minimize spillage drag. Estimates of transonic spillage drag are competitive with those of conventional translating centerbody inlets. The inlet's cruise performance exhibits very low bleed requirements with good recovery and high angle of attack capability.

Application of zonal model on indoor air sensor network design

NASA Astrophysics Data System (ADS)

Chen, Y. Lisa; Wen, Jin

2007-04-01

Growing concerns over the safety of the indoor environment have made the use of sensors ubiquitous. Sensors that detect chemical and biological warfare agents can offer early warning of dangerous contaminants. However, current sensor system design is more informed by intuition and experience rather by systematic design. To develop a sensor system design methodology, a proper indoor airflow modeling approach is needed. Various indoor airflow modeling techniques, from complicated computational fluid dynamics approaches to simplified multi-zone approaches, exist in the literature. In this study, the effects of two airflow modeling techniques, multi-zone modeling technique and zonal modeling technique, on indoor air protection sensor system design are discussed. Common building attack scenarios, using a typical CBW agent, are simulated. Both multi-zone and zonal models are used to predict airflows and contaminant dispersion. Genetic Algorithm is then applied to optimize the sensor location and quantity. Differences in the sensor system design resulting from the two airflow models are discussed for a typical office environment and a large hall environment.

Airflow energy harvesting with high wind velocities for industrial applications

NASA Astrophysics Data System (ADS)

Chew, Z. J.; Tuddenham, S. B.; Zhu, M.

2016-11-01

An airflow energy harvester capable of harvesting energy from vortices at high speed is presented in this paper. The airflow energy harvester is implemented using a modified helical Savonius turbine and an electromagnetic generator. A power management module with maximum power point finding capability is used to manage the harvested energy and convert the low voltage magnitude from the generator to a usable level for wireless sensors. The airflow energy harvester is characterized using vortex generated by air hitting a plate in a wind tunnel. By using an aircraft environment with wind speed of 17 m/s as case study, the output power of the airflow energy harvester is measured to be 126 mW. The overall efficiency of the power management module is 45.76 to 61.2%, with maximum power point tracking efficiency of 94.21 to 99.72% for wind speed of 10 to 18 m/s, and has a quiescent current of 790 nA for the maximum power point tracking circuit.

Spectral analysis of airflow sounds in patent versus occluded tracheostomy tubes: a pilot study in tracheostomized adult patients.

PubMed

Rao, A J; Niwa, H; Watanabe, Y; Fukuta, S; Yanagita, N

1990-05-01

Cannula occlusion is a life-threatening postoperative complication of tracheostomy. Current management largely relies on nursing care for prevention of fatalities because no proven mechanical, machine-based support monitoring exists. The objective of this paper was to address the problem of monitoring the state of cannula patency, based on analysis of airflow acoustic spectral patterns in tracheostomized adult patients in the patent and partially occluded cannula. Tracheal airflow sounds were picked up via a condenser microphone air-coupled to the skin just below the tracheal stoma. Signal output from Mic was amplified, high-pass filtered, digital tape-recorded, and analyzed on a mainframe computer. Although airflow frequencies for patient cannulae were predominantly low-pitched (0.1 to 0.3 kHz), occluded tubes had discrete high-pitched spectral peaks (1.3 to 1.6 kHz). These results suggest that frequency analysis of airflow sounds can identify a change in the status of cannula patency.

Thermal sensation and comfort during exposure to local airflow to face or legs.

PubMed

Yamashita, Kazuaki; Matsuo, Juntaro; Tochihara, Yutaka; Kondo, Youichiro; Takayama, Shizuka; Nagayama, Hiroki

2005-01-01

The present study examined the contribution of local airflow temperature to thermal sensation and comfort in humans. Eight healthy male students were exposed to local airflow to their faces (summer condition) or legs (winter condition) for 30 minutes. Local airflow temperature (Tf) was maintained at 18 degrees C to 36 degrees C, and ambient temperature (Ta) was maintained at 17.4 degrees C to 31.4 degrees C. Each subject was exposed to 16 conditions chosen from the combination of Tf and Ta. Based on the results of multiple regression analysis, the standardized partial regression coefficient of Tf and Ta were determined to be 0.93 and 0.13 in the summer condition, and 0.71 and 0.36 in the winter condition at the end of the exposure. Also, thermal comfort was observed to depend closely on the interrelation between Tf and Ta. The present data suggested that local airflow temperature is an important thermal factor regarding thermal sensation and comfort.

Fuel flexible fuel injector

DOEpatents

Tuthill, Richard S; Davis, Dustin W; Dai, Zhongtao

2015-02-03

A disclosed fuel injector provides mixing of fuel with airflow by surrounding a swirled fuel flow with first and second swirled airflows that ensures mixing prior to or upon entering the combustion chamber. Fuel tubes produce a central fuel flow along with a central airflow through a plurality of openings to generate the high velocity fuel/air mixture along the axis of the fuel injector in addition to the swirled fuel/air mixture.

Computer simulation of airflow through a multi-generation tracheobronchial conducting airway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, B.; Cheng, Yung-Sung; Yeh, Hsu-Chi

1995-12-01

Knowledge of airflow patterns in the human lung is important for an analysis of lung diseases and drug delivery of aerosolized medicine for medical treatment. However, very little systematic information is available on the pattern of airflow in the lung and on how this pattern affects the deposition of toxicants in the lung, and the efficacy of aerosol drug therapy. Most previous studies have only considered the airflow through a single bifurcating airway. However, the flow in a network of more than one bifurcation is more complicated due to the effect of interrelated lung generations. Because of the variation ofmore » airway geometry and flow condition from generation to generation, a single bifurcating airway cannot be taken as a representative for the others in different generations. The flow in the network varies significantly with airway generations because of a redistribution of axial momentum by the secondary flow motions. The influence of the redistribution of flow is expected in every generation. Therefore, a systematic information of the airflow through a multi-generation tracheobronchial conducting airway is needed, and it becomes the purpose of this study. This study has provided information on airflow in a lung model which is necessary to the study of the deposition of toxicants and therapeutic aerosols.« less

Genetic Algorithm (GA)-Based Inclinometer Layout Optimization.

PubMed

Liang, Weijie; Zhang, Ping; Chen, Xianping; Cai, Miao; Yang, Daoguo

2015-04-17

This paper presents numerical simulation results of an airflow inclinometer with sensitivity studies and thermal optimization of the printed circuit board (PCB) layout for an airflow inclinometer based on a genetic algorithm (GA). Due to the working principle of the gas sensor, the changes of the ambient temperature may cause dramatic voltage drifts of sensors. Therefore, eliminating the influence of the external environment for the airflow is essential for the performance and reliability of an airflow inclinometer. In this paper, the mechanism of an airflow inclinometer and the influence of different ambient temperatures on the sensitivity of the inclinometer will be examined by the ANSYS-FLOTRAN CFD program. The results show that with changes of the ambient temperature on the sensing element, the sensitivity of the airflow inclinometer is inversely proportional to the ambient temperature and decreases when the ambient temperature increases. GA is used to optimize the PCB thermal layout of the inclinometer. The finite-element simulation method (ANSYS) is introduced to simulate and verify the results of our optimal thermal layout, and the results indicate that the optimal PCB layout greatly improves (by more than 50%) the sensitivity of the inclinometer. The study may be useful in the design of PCB layouts that are related to sensitivity improvement of gas sensors.

Genetic Algorithm (GA)-Based Inclinometer Layout Optimization

PubMed Central

Liang, Weijie; Zhang, Ping; Chen, Xianping; Cai, Miao; Yang, Daoguo

2015-01-01

This paper presents numerical simulation results of an airflow inclinometer with sensitivity studies and thermal optimization of the printed circuit board (PCB) layout for an airflow inclinometer based on a genetic algorithm (GA). Due to the working principle of the gas sensor, the changes of the ambient temperature may cause dramatic voltage drifts of sensors. Therefore, eliminating the influence of the external environment for the airflow is essential for the performance and reliability of an airflow inclinometer. In this paper, the mechanism of an airflow inclinometer and the influence of different ambient temperatures on the sensitivity of the inclinometer will be examined by the ANSYS-FLOTRAN CFD program. The results show that with changes of the ambient temperature on the sensing element, the sensitivity of the airflow inclinometer is inversely proportional to the ambient temperature and decreases when the ambient temperature increases. GA is used to optimize the PCB thermal layout of the inclinometer. The finite-element simulation method (ANSYS) is introduced to simulate and verify the results of our optimal thermal layout, and the results indicate that the optimal PCB layout greatly improves (by more than 50%) the sensitivity of the inclinometer. The study may be useful in the design of PCB layouts that are related to sensitivity improvement of gas sensors. PMID:25897500

Tuberculosis associates with both airflow obstruction and low lung function: BOLD results.

PubMed

Amaral, André F S; Coton, Sonia; Kato, Bernet; Tan, Wan C; Studnicka, Michael; Janson, Christer; Gislason, Thorarinn; Mannino, David; Bateman, Eric D; Buist, Sonia; Burney, Peter G J

2015-10-01

In small studies and cases series, a history of tuberculosis has been associated with both airflow obstruction, which is characteristic of chronic obstructive pulmonary disease, and restrictive patterns on spirometry. The objective of the present study was to assess the association between a history of tuberculosis and airflow obstruction and spirometric abnormalities in adults.The study was performed in adults, aged 40 years and above, who took part in the multicentre, cross-sectional, general population-based Burden of Obstructive Lung Disease study, and had provided acceptable post-bronchodilator spirometry measurements and information on a history of tuberculosis. The associations between a history of tuberculosis and airflow obstruction and spirometric restriction were assessed within each participating centre, and estimates combined using meta-analysis. These estimates were stratified by high- and low/middle-income countries, according to gross national income.A self-reported history of tuberculosis was associated with airflow obstruction (adjusted odds ratio 2.51, 95% CI 1.83-3.42) and spirometric restriction (adjusted odds ratio 2.13, 95% CI 1.42-3.19).A history of tuberculosis was associated with both airflow obstruction and spirometric restriction, and should be considered as a potentially important cause of obstructive disease and low lung function, particularly where tuberculosis is common. Copyright ©ERS 2015.

Tuberculosis associates with both airflow obstruction and low lung function: BOLD results

PubMed Central

Amaral, André F. S.; Coton, Sonia; Kato, Bernet; Tan, Wan C.; Studnicka, Michael; Janson, Christer; Gislason, Thorarinn; Mannino, David; Bateman, Eric D.; Buist, Sonia; Burney, Peter G. J.

2015-01-01

Background In small studies and cases series, a history of tuberculosis has been associated with both airflow obstruction, which is characteristic of chronic obstructive pulmonary disease, and restrictive patterns on spirometry. Objective To assess the association between a history of tuberculosis and airflow obstruction and spirometric abnormalities in adults. Methods The study was performed in adults, aged 40 and above, who took part in the multicentre cross-sectional, general population-based, Burden of Obstructive Lung Disease study, had provided acceptable post-bronchodilator spirometry measurements and information on a history of tuberculosis. The associations between a history of tuberculosis and airflow obstruction and spirometric restriction were assessed within each participating centre, and estimates combined using meta-analysis. These estimates were stratified by high and low/middle income countries, according to gross national income. Results A self-reported history of tuberculosis was associated with airflow obstruction (adjusted odds ratio = 2.51, 95% confidence interval 1.83-3.42) and spirometric restriction (adjusted odds ratio = 2.13, 95% confidence interval 1.42-3.19). Conclusion A history of tuberculosis was associated with both airflow obstruction and spirometric restriction, and should be considered as a potentially important cause of obstructive disease and low lung function, particularly where tuberculosis is common. PMID:26113680

Transient Dynamics Simulation of Airflow in a CT-Scanned Human Airway Tree: More or Fewer Terminal Bronchi?

PubMed Central

Zhang, Baihua; Li, Jianhua; Yue, Yong; Qian, Wei

2017-01-01

Using computational fluid dynamics (CFD) method, the feasibility of simulating transient airflow in a CT-based airway tree with more than 100 outlets for a whole respiratory period is studied, and the influence of truncations of terminal bronchi on CFD characteristics is investigated. After an airway model with 122 outlets is extracted from CT images, the transient airflow is simulated. Spatial and temporal variations of flow velocity, wall pressure, and wall shear stress are presented; the flow pattern and lobar distribution of air are gotten as well. All results are compared with those of a truncated model with 22 outlets. It is found that the flow pattern shows lobar heterogeneity that the near-wall air in the trachea is inhaled into the upper lobe while the center flow enters the other lobes, and the lobar distribution of air is significantly correlated with the outlet area ratio. The truncation decreases airflow to right and left upper lobes and increases the deviation of airflow distributions between inspiration and expiration. Simulating the transient airflow in an airway tree model with 122 bronchi using CFD is feasible. The model with more terminal bronchi decreases the difference between the lobar distributions at inspiration and at expiration. PMID:29333194

Estimating Vocal Effort from the Aerodynamics of Labial Fricatives: A Feasibility Study.

PubMed

Meynadier, Yohann; El Hajj, Anita; Pitermann, Michel; Legou, Thierry; Giovanni, Antoine

2017-09-12

Vocal effort in loud voice is produced with increased subglottal pressure during vowels and increased supraglottal pressure during consonants. In the paper, our main objective is to check whether it was supported by a parallel increase in the airflow resistance of the laryngeal articulator and of the supralaryngeal articulator, here the lips. For this comparison, our choice fell on the fricative consonants, as their production allows perfectly synchronous air pressure and airflow measurements. Also, the calculation of the real instantaneous aerodynamic resistance is possible with fricatives-as it is with vowels-whereas it is not possible with plosives. The present feasibility study on a healthy subject is based on direct subglottal and intraoral pressures and airflow measured for /f/ or /v/ and from the contiguous vowel produced in VCVCV nonsense words at different levels of intensity. The results support that the airflow resistances at the lips and that at the larynx are quite parallel. The airflow resistance at the lips during labial fricative production could provide a good picture of the laryngeal resistance during the production of continuous speech. This suggests clinical applications using both noninvasive inferred measurements of subglottal pressure variation and direct noninferred airflow measurements from more natural speech production tasks. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Validity of peak expiratory flow measurement in assessing reversibility of airflow obstruction.

PubMed Central

Dekker, F W; Schrier, A C; Sterk, P J; Dijkman, J H

1992-01-01

BACKGROUND: Assessing the reversibility of airflow obstruction by peak expiratory (PEF) measurements would be practicable in general practice, but its usefulness has not been investigated. METHODS: PEF measurements were performed (miniWright peak flow meter) in 73 general practice patients (aged 40 to 84) with a history of asthma or chronic obstructive lung disease before and after 400 micrograms inhaled sulbutamol. The change in PEF was compared with the change in forced expiratory volume in one second (FEV1). Reversible airflow obstruction was analysed in two ways according to previous criteria. When defined as a 9% or greater increase in FEV1 expressed as a percentage of predicted values reversibility was observed in 42% of patients. Relative operating characteristic analysis showed that an absolute improvement in PEF of 60 l/min or more gave optimal discrimination between patients with reversible and irreversible airflow obstruction (the sensitivity and specificity of an increase of 60 l/min in detecting a 9% or more increase in FEV1 as a percentage of predicted values were 68% and 93% respectively, with a positive predictive value of 87%). When defined as an increase of 190 ml or more in FEV1, reversible airflow obstruction was observed in 53% of patients. Again an absolute improvement in PEF of 60 l/min or more gave optimal discrimination between patients with reversible and irreversible airflow obstruction (sensitivity 56%, specificity 94%, and positive predictive value 92%). CONCLUSION: Absolute changes in PEF can be used as a simple technique to diagnose reversible airflow obstruction in patients from general practice. PMID:1519192

Relationships among Smoking Habits, Airflow Limitations, and Metabolic Abnormalities in School Workers

PubMed Central

Horie, Masafumi; Noguchi, Satoshi; Tanaka, Wakae; Goto, Yasushi; Yoshihara, Hisanao; Kawakami, Masaki; Suzuki, Masaru; Sakamoto, Yoshio

2013-01-01

Background Chronic obstructive pulmonary disease is caused mainly by habitual smoking and is common among elderly individuals. It involves not only airflow limitation but also metabolic disorders, leading to increased cardiovascular morbidity and mortality. Objective We evaluated relationships among smoking habits, airflow limitation, and metabolic abnormalities. Methods Between 2001 and 2008, 15,324 school workers (9700 males, 5624 females; age: ≥30 years) underwent medical checkups, including blood tests and spirometry. They also responded to a questionnaire on smoking habits and medical history. Results Airflow limitation was more prevalent in current smokers than in ex-smokers and never-smokers in men and women. The frequency of hypertriglyceridemia was higher in current smokers in all age groups, and those of low high-density-lipoprotein cholesterolemia and diabetes mellitus were higher in current smokers in age groups ≥ 40 s in men, but not in women. There were significant differences in the frequencies of metabolic abnormalities between subjects with airflow limitations and those without in women, but not in men. Smoking index was an independent factor associated with increased frequencies of hypertriglyceridemia (OR 1.015; 95% CI: 1.012–1.018; p<0.0001) and low high-density-lipoprotein cholesterolemia (1.013; 1.010–1.016; p<0.0001) in men. Length of smoking cessation was an independent factor associated with a decreased frequency of hypertriglyceridemia (0.984; 0.975–0.994; p = 0.007). Conclusions Habitual smoking causes high incidences of airflow limitation and metabolic abnormalities. Women, but not men, with airflow limitation had higher frequencies of metabolic abnormalities. PMID:24312268

Relationships among smoking habits, airflow limitations, and metabolic abnormalities in school workers.

PubMed

Horie, Masafumi; Noguchi, Satoshi; Tanaka, Wakae; Goto, Yasushi; Yoshihara, Hisanao; Kawakami, Masaki; Suzuki, Masaru; Sakamoto, Yoshio

2013-01-01

Chronic obstructive pulmonary disease is caused mainly by habitual smoking and is common among elderly individuals. It involves not only airflow limitation but also metabolic disorders, leading to increased cardiovascular morbidity and mortality. We evaluated relationships among smoking habits, airflow limitation, and metabolic abnormalities. Between 2001 and 2008, 15,324 school workers (9700 males, 5624 females; age: ≥ 30 years) underwent medical checkups, including blood tests and spirometry. They also responded to a questionnaire on smoking habits and medical history. Airflow limitation was more prevalent in current smokers than in ex-smokers and never-smokers in men and women. The frequency of hypertriglyceridemia was higher in current smokers in all age groups, and those of low high-density-lipoprotein cholesterolemia and diabetes mellitus were higher in current smokers in age groups ≥ 40 s in men, but not in women. There were significant differences in the frequencies of metabolic abnormalities between subjects with airflow limitations and those without in women, but not in men. Smoking index was an independent factor associated with increased frequencies of hypertriglyceridemia (OR 1.015; 95% CI: 1.012-1.018; p<0.0001) and low high-density-lipoprotein cholesterolemia (1.013; 1.010-1.016; p<0.0001) in men. Length of smoking cessation was an independent factor associated with a decreased frequency of hypertriglyceridemia (0.984; 0.975-0.994; p = 0.007). Habitual smoking causes high incidences of airflow limitation and metabolic abnormalities. Women, but not men, with airflow limitation had higher frequencies of metabolic abnormalities.

Influence of liquid-volume and airflow rates on spray application quality and homogeneity in super-intensive olive tree canopies.

PubMed

Miranda-Fuentes, Antonio; Rodríguez-Lizana, Antonio; Gil, Emilio; Agüera-Vega, J; Gil-Ribes, Jesús A

2015-12-15

Olive is a key crop in Europe, especially in countries around the Mediterranean Basin. Optimising the parameters of a spray is essential for sustainable pesticide use, especially in high-input systems, such as the super-intensive hedgerow system. Parameters may be optimised by adjusting the applied volume and airflow rate of sprays, in addition to the liquid to air proportion and the relationship between air velocity and airflow rate. Two spray experiments using a commercial airblast sprayer were conducted in a super-intensive orchard to study how varying the liquid volume rate (testing volumes of 182, 619, and 1603 l ha(-1)) and volumetric airflow rate (with flow rates of 11.93, 8.90, and 6.15 m(3) s(-1)) influences the coverage parameters and the amount and distribution of deposits in different zones of the canopy.. Our results showed that an increase in the application volume raised the mean deposit and percentage coverage, but decreased the application efficiency, spray penetration, and deposit homogeneity. Furthermore, we found that the volumetric airflow rate had a lower influence on the studied parameters than the liquid volume; however, an increase in the airflow rate improved the application efficiency and homogeneity to a certain threshold, after which the spray quality decreased. This decrease was observed in the high-flow treatment. Our results demonstrate that intermediate liquid volume rates and volumetric airflow rates are required for the optimal spraying of pesticides on super-intensive olive crops, and would reduce current pollution levels. Copyright © 2015 Elsevier B.V. All rights reserved.

Performance Analysis of a Modular Small-Diamter Air Distribution System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poerschke, Andrew; Rudd, Armin

2016-03-01

This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to be brought easily within conditioned space via interior partition walls. Centrally locating the air handler unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives an equal amount of airflow, regardless of the duct position on the box. Furthermore, within a reasonable set of length restrictions, each duct continues to receive similar airflow. The design method uses anmore » additive approach to reach the total needed zonal airflow. Once the cubic feet per minute needed to satisfy the thermal load of a zone has been determined, the total number of duct runs to a zone can be calculated by dividing the required airflow by the standard airflow from each duct. The additive approach greatly simplifies the design effort and reduces the potential for duct design mistakes to be made. Measured results indicate that this plenum design can satisfy the heating load. However, the total airflow falls short of satisfying the cooling load in a hypothetical building. Static pressure inside the plenum box of 51.5 Pa limited the total airflow of the attached mini-split heat pump blower, thus limiting the total thermal capacity. Fan energy consumption is kept to 0.16 to 0.22 watt/CFM by using short duct runs and smooth duct material.« less

The Risk Factors and Clinical Course of Asthma with Fixed Airflow Limitation.

PubMed

Pothirat, Chaicharn; Chaiwong, Warawut; Liwsrisakun, Chalerm; Bumroongkit, Chaiwat; Deesomchok, Athavudh; Theerakittikul, Theerakorn; Limsukon, Atikun; Phetsuk, Nittaya

2016-07-01

To identify risk factors and clinical course of asthma with fixed airflow limitation. A retrospective case-control study of asthma patients was conducted over a 15-month period. Asthma with fixed airflow limitation patients were defined as chronic asthmatics who had both post-bronchodilator (BD) and on-treatment ratio of forced expiratory in first second (FEV1)/forced vital capacity (FVC) persistently less than 0.7, whereas usual chronic asthma patients had post-BD and/or on-treatment ratio of FEV1/FVC more than 0.7. Serial asthma control tests (ACT), medication used, exacerbations were assessed. The risk factors were analyzed using logistic regression. Clinical characteristics between groups were compared using Student’s t-test and Fisher’s exact test. One hundred twenty from 142 eligible subjects were enrolled. They had asthma with fixed airflow limitation (n = 40) and usual chronic asthma (n = 80). Potential risk factors of asthma with fixed airflow limitation included early disease onset (age <15 years) [(adjusted odd ratio (OR) = 3.9, 95% confidence interval (CI) 1.9-8.3)] with longer disease duration (adjusted OR = 8.4, 95% CI 4.6-15.4 for >30 years). Asthma with fixed airflow limitation patients had lower ACT scores (p<0.001), lower level of asthma control (p<0.001), required more asthma medications (p = 0.002), and higher rates of hospitalization (p = 0.001) than usual chronic asthma. The potential risk factors of asthma with fixed airflow limitation were earlier disease onset and longer disease duration. They had poorer asthma control, more medications needed, and higher rates of exacerbation than usual chronic asthma.

The effect of airflow rates and aeration mode on the respiration activity of four organic wastes: Implications on the composting process.

PubMed

Mejias, Laura; Komilis, Dimitrios; Gea, Teresa; Sánchez, Antoni

2017-07-01

The aim of this study was to assess the effect of the airflow and of the aeration mode on the composting process of non-urban organic wastes that are found in large quantities worldwide, namely: (i) a fresh, non-digested, sewage sludge (FSS), (ii) an anaerobically digested sewage sludge (ADSS), (iii) cow manure (CM) and (iv) pig sludge (PS). This assessment was done using respirometric indices. Two aeration modes were tested, namely: (a) a constant air flowrate set at three different initial fixed airflow rates, and (b) an oxygen uptake rate (OUR)-controlled airflow rate. The four wastes displayed the same behaviour namely a limited biological activity at low aeration, while, beyond a threshold value, the increase of the airflow did not significantly increase the dynamic respiration indices (DRI 1 max , DRI 24 max and AT 4 ). The threshold airflow rate varied among wastes and ranged from 42NL air kg -1 DMh -1 for CM and from 67 to 77NL air kg -1 DMh -1 for FSS, ADSS and PS. Comparing the two aeration modes tested (constant air flow, OUR controlled air flow), no statistically significant differences were calculated between the respiration activity indices obtained at those two aeration modes. The results can be considered representative for urban and non-urban organic wastes and establish a general procedure to measure the respiration activity without limitations by airflow. This will permit other researchers to provide consistent results during the measurement of the respiration activity. Results indicate that high airflows are not required to establish the maximum respiration activity. This can result in energy savings and the prevention of off-gas treatment problems due to the excessive aeration rate in full scale composting plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Proportion and clinical characteristics of non-asthmatic non-smokers among adults with airflow obstruction.

PubMed

Takiguchi, Hiroto; Takeuchi, Tomoe; Niimi, Kyoko; Tomomatsu, Hiromi; Tomomatsu, Katsuyoshi; Hayama, Naoki; Oguma, Tsuyoshi; Aoki, Takuya; Urano, Tetsuya; Asai, Satomi; Miyachi, Hayato; Asano, Koichiro

2018-01-01

Chronic obstructive pulmonary disease (COPD) mainly develops after long-term exposure to cigarette or biomass fuel smoke, but also occurs in non-smokers with or without a history of asthma. We investigated the proportion and clinical characteristics of non-smokers among middle-aged to elderly subjects with airflow obstruction. We retrospectively analyzed 1,892 subjects aged 40-89 years who underwent routine preoperative spirometry at a tertiary university hospital in Japan. Airflow obstruction was defined as a forced expiratory volume in 1 second (FEV1)/forced vital capacity < 0.7 or as the lower limit of the normal. Among 323 patients presenting with FEV1/forced vital capacity < 0.7, 43 had asthma and 280 did not. Among the non-asthmatic patients with airflow obstruction, 94 (34%) were non-smokers. A larger number of women than men with airflow obstruction had asthma (26% vs. 7.6%, p < 0.001), or were non-smokers among non-asthmatics (72% vs. 20%, p < 0.001). Non-asthmatic non-smokers, rather than non-asthmatic smokers, asthmatic non-smokers, and asthmatic smokers, exhibited better pulmonary function (median FEV1: 79% of predicted FEV1 vs. 73%, 69%, and 66%, respectively, p = 0.005) and less dyspnea on exertion (1% vs. 12%, 12%, and 28%, respectively, p = 0.001). Pulmonary emphysema on thoracic computed tomography was less common in non-smokers (p < 0.001). Using the lower limit of the normal to define airflow obstruction yielded similar results. There are a substantial number of non-smokers with airflow obstruction compatible with COPD in Japan. In this study, airflow obstruction in non-smokers was more common in women and likelier to result in mild functional and pathological abnormalities than in smokers. Further studies are warranted to investigate the long-term prognosis and appropriate management of this population in developed countries, especially in women.

Proportion and clinical characteristics of non-asthmatic non-smokers among adults with airflow obstruction

PubMed Central

Takiguchi, Hiroto; Takeuchi, Tomoe; Niimi, Kyoko; Tomomatsu, Hiromi; Tomomatsu, Katsuyoshi; Hayama, Naoki; Oguma, Tsuyoshi; Urano, Tetsuya; Asai, Satomi; Miyachi, Hayato; Asano, Koichiro

2018-01-01

Background and objectives Chronic obstructive pulmonary disease (COPD) mainly develops after long-term exposure to cigarette or biomass fuel smoke, but also occurs in non-smokers with or without a history of asthma. We investigated the proportion and clinical characteristics of non-smokers among middle-aged to elderly subjects with airflow obstruction. Methods We retrospectively analyzed 1,892 subjects aged 40–89 years who underwent routine preoperative spirometry at a tertiary university hospital in Japan. Airflow obstruction was defined as a forced expiratory volume in 1 second (FEV1)/forced vital capacity < 0.7 or as the lower limit of the normal. Results Among 323 patients presenting with FEV1/forced vital capacity < 0.7, 43 had asthma and 280 did not. Among the non-asthmatic patients with airflow obstruction, 94 (34%) were non-smokers. A larger number of women than men with airflow obstruction had asthma (26% vs. 7.6%, p < 0.001), or were non-smokers among non-asthmatics (72% vs. 20%, p < 0.001). Non-asthmatic non-smokers, rather than non-asthmatic smokers, asthmatic non-smokers, and asthmatic smokers, exhibited better pulmonary function (median FEV1: 79% of predicted FEV1 vs. 73%, 69%, and 66%, respectively, p = 0.005) and less dyspnea on exertion (1% vs. 12%, 12%, and 28%, respectively, p = 0.001). Pulmonary emphysema on thoracic computed tomography was less common in non-smokers (p < 0.001). Using the lower limit of the normal to define airflow obstruction yielded similar results. Conclusions There are a substantial number of non-smokers with airflow obstruction compatible with COPD in Japan. In this study, airflow obstruction in non-smokers was more common in women and likelier to result in mild functional and pathological abnormalities than in smokers. Further studies are warranted to investigate the long-term prognosis and appropriate management of this population in developed countries, especially in women. PMID:29742176

Chronic obstructive pulmonary disease with mild airflow limitation: current knowledge and proposal for future research - a consensus document from six scientific societies.

PubMed

Rossi, Andrea; Butorac-Petanjek, Bojana; Chilosi, Marco; Cosío, Borja G; Flezar, Matjaz; Koulouris, Nikolaos; Marin, José; Miculinic, Neven; Polese, Guido; Samaržija, Miroslav; Skrgat, Sabina; Vassilakopoulos, Theodoros; Vukić-Dugac, Andrea; Zakynthinos, Spyridon; Miravitlles, Marc

2017-01-01

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality and morbidity worldwide, with high and growing prevalence. Its underdiagnosis and hence under-treatment is a general feature across all countries. This is particularly true for the mild or early stages of the disease, when symptoms do not yet interfere with daily living activities and both patients and doctors are likely to underestimate the presence of the disease. A diagnosis of COPD requires spirometry in subjects with a history of exposure to known risk factors and symptoms. Postbronchodilator forced expiratory volume in 1 second (FEV 1 )/forced vital capacity <0.7 or less than the lower limit of normal confirms the presence of airflow limitation, the severity of which can be measured by FEV 1 % predicted: stage 1 defines COPD with mild airflow limitation, which means postbronchodilator FEV 1 ≥80% predicted. In recent years, an elegant series of studies has shown that "exclusive reliance on spirometry, in patients with mild airflow limitation, may result in underestimation of clinically important physiologic impairment". In fact, exercise tolerance, diffusing capacity, and gas exchange can be impaired in subjects at a mild stage of airflow limitation. Furthermore, growing evidence indicates that smokers without overt abnormal spirometry have respiratory symptoms and undergo therapy. This is an essential issue in COPD. In fact, on one hand, airflow limitation, even mild, can unduly limit the patient's physical activity, with deleterious consequences on quality of life and even survival; on the other hand, particularly in younger subjects, mild airflow limitation might coincide with the early stage of the disease. Therefore, we thought that it was worthwhile to analyze further and discuss this stage of "mild COPD". To this end, representatives of scientific societies from five European countries have met and developed this document to stimulate the attention of the scientific community on COPD with "mild" airflow limitation. The aim of this document is to highlight some key features of this important concept and help the practicing physician to understand better what is behind "mild" COPD. Future research should address two major issues: first, whether mild airflow limitation represents an early stage of COPD and what the mechanisms underlying the evolution to more severe stages of the disease are; and second, not far removed from the first, whether regular treatment should be considered for COPD patients with mild airflow limitation, either to prevent progression of the disease or to encourage and improve physical activity or both.

Minimum airflow reset of single-duct VAV terminal boxes

NASA Astrophysics Data System (ADS)

Cho, Young-Hum

Single duct Variable Air Volume (VAV) systems are currently the most widely used type of HVAC system in the United States. When installing such a system, it is critical to determine the minimum airflow set point of the terminal box, as an optimally selected set point will improve the level of thermal comfort and indoor air quality (IAQ) while at the same time lower overall energy costs. In principle, this minimum rate should be calculated according to the minimum ventilation requirement based on ASHRAE standard 62.1 and maximum heating load of the zone. Several factors must be carefully considered when calculating this minimum rate. Terminal boxes with conventional control sequences may result in occupant discomfort and energy waste. If the minimum rate of airflow is set too high, the AHUs will consume excess fan power, and the terminal boxes may cause significant simultaneous room heating and cooling. At the same time, a rate that is too low will result in poor air circulation and indoor air quality in the air-conditioned space. Currently, many scholars are investigating how to change the algorithm of the advanced VAV terminal box controller without retrofitting. Some of these controllers have been found to effectively improve thermal comfort, indoor air quality, and energy efficiency. However, minimum airflow set points have not yet been identified, nor has controller performance been verified in confirmed studies. In this study, control algorithms were developed that automatically identify and reset terminal box minimum airflow set points, thereby improving indoor air quality and thermal comfort levels, and reducing the overall rate of energy consumption. A theoretical analysis of the optimal minimum airflow and discharge air temperature was performed to identify the potential energy benefits of resetting the terminal box minimum airflow set points. Applicable control algorithms for calculating the ideal values for the minimum airflow reset were developed and applied to actual systems for performance validation. The results of the theoretical analysis, numeric simulations, and experiments show that the optimal control algorithms can automatically identify the minimum rate of heating airflow under actual working conditions. Improved control helps to stabilize room air temperatures. The vertical difference in the room air temperature was lower than the comfort value. Measurements of room CO2 levels indicate that when the minimum airflow set point was reduced it did not adversely affect the indoor air quality. According to the measured energy results, optimal control algorithms give a lower rate of reheating energy consumption than conventional controls.

Chronic obstructive pulmonary disease with mild airflow limitation: current knowledge and proposal for future research – a consensus document from six scientific societies

PubMed Central

Rossi, Andrea; Butorac-Petanjek, Bojana; Chilosi, Marco; Cosío, Borja G; Flezar, Matjaz; Koulouris, Nikolaos; Marin, José; Miculinic, Neven; Polese, Guido; Samaržija, Miroslav; Skrgat, Sabina; Vassilakopoulos, Theodoros; Vukić-Dugac, Andrea; Zakynthinos, Spyridon; Miravitlles, Marc

2017-01-01

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality and morbidity worldwide, with high and growing prevalence. Its underdiagnosis and hence under-treatment is a general feature across all countries. This is particularly true for the mild or early stages of the disease, when symptoms do not yet interfere with daily living activities and both patients and doctors are likely to underestimate the presence of the disease. A diagnosis of COPD requires spirometry in subjects with a history of exposure to known risk factors and symptoms. Postbronchodilator forced expiratory volume in 1 second (FEV1)/forced vital capacity <0.7 or less than the lower limit of normal confirms the presence of airflow limitation, the severity of which can be measured by FEV1% predicted: stage 1 defines COPD with mild airflow limitation, which means postbronchodilator FEV1 ≥80% predicted. In recent years, an elegant series of studies has shown that “exclusive reliance on spirometry, in patients with mild airflow limitation, may result in underestimation of clinically important physiologic impairment”. In fact, exercise tolerance, diffusing capacity, and gas exchange can be impaired in subjects at a mild stage of airflow limitation. Furthermore, growing evidence indicates that smokers without overt abnormal spirometry have respiratory symptoms and undergo therapy. This is an essential issue in COPD. In fact, on one hand, airflow limitation, even mild, can unduly limit the patient’s physical activity, with deleterious consequences on quality of life and even survival; on the other hand, particularly in younger subjects, mild airflow limitation might coincide with the early stage of the disease. Therefore, we thought that it was worthwhile to analyze further and discuss this stage of “mild COPD”. To this end, representatives of scientific societies from five European countries have met and developed this document to stimulate the attention of the scientific community on COPD with “mild” airflow limitation. The aim of this document is to highlight some key features of this important concept and help the practicing physician to understand better what is behind “mild” COPD. Future research should address two major issues: first, whether mild airflow limitation represents an early stage of COPD and what the mechanisms underlying the evolution to more severe stages of the disease are; and second, not far removed from the first, whether regular treatment should be considered for COPD patients with mild airflow limitation, either to prevent progression of the disease or to encourage and improve physical activity or both. PMID:28919728

Grain dust and respiratory health in South African milling workers.

PubMed Central

Bachmann, M; Myers, J E

1991-01-01

Respiratory health was investigated in 224 grain milling workers. The likelihood of respiratory symptoms and chronic airflow limitation was raised for workers exposed to dust independent of the effects of smoking. Smokers were more likely than non-smokers to respond to a bronchodilator at the end of the working week. Dust was more strongly associated with most abnormal outcomes than was smoking. Subjective categories of exposure to dust were more strongly associated with most abnormal outcomes than were objective categories. The prevalence of all symptoms at the time of a survey conducted at the mill six years before was higher in workers who subsequently left the mill than in those who remained employed although the differences were not significant. PMID:1931723

Airflow and thrust calibration of an F100 engine, S/N P680059, at selected flight conditions

NASA Technical Reports Server (NTRS)

Biesiadny, T. J.; Lee, D.; Rodriguez, J. R.

1978-01-01

An airflow and thrust calibration of an F100 engine, S/N P680059, was conducted to study airframe propulsion system integration losses in turbofan-powered high-performance aircraft. The tests were conducted with and without thrust augmentation for a variety of simulated flight conditions with emphasis on the transonic regime. The resulting corrected airflow data generalized into one curve with corrected fan speed while corrected gross thrust increased as simulated flight conditions increased. Overall agreement between measured data and computed results was 1 percent for corrected airflow and -1 1/2 percent for gross thrust. The results of an uncertainty analysis are presented for both parameters at each simulated flight condition.

Respiratory Source Control Using Surgical Masks With Nanofiber Media

PubMed Central

Skaria, Shaji D.; Smaldone, Gerald C.

2014-01-01

Background: Potentially infected individuals (‘source’) are sometimes encouraged to use face masks to reduce exposure of their infectious aerosols to others (‘receiver’). To improve compliance with Respiratory Source Control via face mask and therefore reduce receiver exposure, a mask should be comfortable and effective. We tested a novel face mask designed to improve breathability and filtration using nanofiber filtration. Methods: Using radiolabeled test aerosols and a calibrated exposure chamber simulating source to receiver interaction, facepiece function was measured with a life-like ventilated manikin model. Measurements included mask airflow resistance (pressure difference during breathing), filtration, (mask capture of exhaled radiolabeled test aerosols), and exposure (the transfer of ‘infectious’ aerosols from the ‘source’ to a ‘receiver’). Polydisperse aerosols were measured at the source with a mass median aerodynamic diameter of 0.95 µm. Approximately 90% of the particles were <2.0 µm. Tested facepieces included nanofiber prototype surgical masks, conventional surgical masks, and for comparison, an N95-class filtering facepiece respirator (commonly known as an ‘N95 respirator’). Airflow through and around conventional surgical face mask and nanofiber prototype face mask was visualized using Schlieren optical imaging. Results: Airflow resistance [ΔP, cmH2O] across sealed surgical masks (means: 0.1865 and 0.1791 cmH2O) approached that of the N95 (mean: 0.2664 cmH2O). The airflow resistance across the nanofiber face mask whether sealed or not sealed (0.0504 and 0.0311 cmH2O) was significantly reduced in comparison. In addition, ‘infected’ source airflow filtration and receiver exposure levels for nanofiber face masks placed on the source were comparable to that achieved with N95 placed on the source; 98.98% versus 82.68% and 0.0194 versus 0.0557, respectively. Compared to deflection within and around the conventional face masks, Schlieren optical imaging demonstrated enhanced airflow through the nanofiber mask. Conclusions: Substituting nanofiber for conventional filter media significantly reduced face mask airflow resistance directing more airflow through the face mask resulting in enhanced filtration. Respiratory source control efficacy similar to that achieved through the use of an N95 respirator worn by the source and decreased airflow resistance using nanofiber masks may improve compliance and reduce receiver exposure. PMID:24737728

Respiratory source control using surgical masks with nanofiber media.

PubMed

Skaria, Shaji D; Smaldone, Gerald C

2014-07-01

Potentially infected individuals ('source') are sometimes encouraged to use face masks to reduce exposure of their infectious aerosols to others ('receiver'). To improve compliance with Respiratory Source Control via face mask and therefore reduce receiver exposure, a mask should be comfortable and effective. We tested a novel face mask designed to improve breathability and filtration using nanofiber filtration. Using radiolabeled test aerosols and a calibrated exposure chamber simulating source to receiver interaction, facepiece function was measured with a life-like ventilated manikin model. Measurements included mask airflow resistance (pressure difference during breathing), filtration, (mask capture of exhaled radiolabeled test aerosols), and exposure (the transfer of 'infectious' aerosols from the 'source' to a 'receiver'). Polydisperse aerosols were measured at the source with a mass median aerodynamic diameter of 0.95 µm. Approximately 90% of the particles were <2.0 µm. Tested facepieces included nanofiber prototype surgical masks, conventional surgical masks, and for comparison, an N95-class filtering facepiece respirator (commonly known as an 'N95 respirator'). Airflow through and around conventional surgical face mask and nanofiber prototype face mask was visualized using Schlieren optical imaging. Airflow resistance [ΔP, cmH2O] across sealed surgical masks (means: 0.1865 and 0.1791 cmH2O) approached that of the N95 (mean: 0.2664 cmH2O). The airflow resistance across the nanofiber face mask whether sealed or not sealed (0.0504 and 0.0311 cmH2O) was significantly reduced in comparison. In addition, 'infected' source airflow filtration and receiver exposure levels for nanofiber face masks placed on the source were comparable to that achieved with N95 placed on the source; 98.98% versus 82.68% and 0.0194 versus 0.0557, respectively. Compared to deflection within and around the conventional face masks, Schlieren optical imaging demonstrated enhanced airflow through the nanofiber mask. Substituting nanofiber for conventional filter media significantly reduced face mask airflow resistance directing more airflow through the face mask resulting in enhanced filtration. Respiratory source control efficacy similar to that achieved through the use of an N95 respirator worn by the source and decreased airflow resistance using nanofiber masks may improve compliance and reduce receiver exposure. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Monitoring minimization of grade B environments based on risk assessment using three-dimensional airflow measurements and computer simulation.

PubMed

Katayama, Hirohito; Higo, Takashi; Tokunaga, Yuji; Katoh, Shigeo; Hiyama, Yukio; Morikawa, Kaoru

2008-01-01

A practical, risk-based monitoring approach using the combined data collected from actual experiments and computer simulations was developed for the qualification of an EU GMP Annex 1 Grade B, ISO Class 7 area. This approach can locate and minimize the representative number of sampling points used for microbial contamination risk assessment. We conducted a case study on an aseptic clean room, newly constructed and specifically designed for the use of a restricted access barrier system (RABS). Hotspots were located using three-dimensional airflow analysis based on a previously published empirical measurement method, the three-dimensional airflow analysis. Local mean age of air (LMAA) values were calculated based on computer simulations. Comparable results were found using actual measurements and simulations, demonstrating the potential usefulness of such tools in estimating contamination risks based on the airflow characteristics of a clean room. Intensive microbial monitoring and particle monitoring at the Grade B environmental qualification stage, as well as three-dimensional airflow analysis, were also conducted to reveal contamination hotspots. We found representative hotspots were located at perforated panels covering the air exhausts where the major piston airflows collect in the Grade B room, as well as at any locations within the room that were identified as having stagnant air. However, we also found that the floor surface air around the exit airway of the RABS EU GMP Annex 1 Grade A, ISO Class 5 area was always remarkably clean, possibly due to the immediate sweep of the piston airflow, which prevents dispersed human microbes from falling in a Stokes-type manner on settling plates placed on the floor around the Grade A exit airway. In addition, this airflow is expected to be clean with a significantly low LMAA. Based on these observed results, we propose a simplified daily monitoring program to monitor microbial contamination in Grade B environments. To locate hotspots we propose using a combination of computer simulation, actual airflow measurements, and intensive environmental monitoring at the qualification stage. Thereafter, instead of particle or microbial air monitoring, we recommend the use of microbial surface monitoring at the main air exhaust. These measures would be sufficient to assure the efficiency of the monitoring program, as well as to minimize the number of surface sampling points used in environments surrounding a RABS.

Reducing airflow energy use in multiple zone vav systems

NASA Astrophysics Data System (ADS)

Tukur, Ahmed Gidado

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 are estimated by shifting the damper distribution mean at each time to this maximum value and reducing the static pressure to achieve the same overall system airflow rate. The methodology was tested on three different buildings with varying system characteristics. Savings estimates correlated well to the savings actually realized from SPR. This result has significant implications for energy service providers, who could use the predictions to guarantee savings from SPR.

Thermal performance characterization of residential wall systems using a calibrated hot box with airflow induced by differential pressures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, D.C.; Ober, D.G.; Goodrow, J.T.

1995-09-01

ASTM E 283 ad ASTM E 1424 in conjunction with ASTM C 976 were used to study the effect of airflow on thermal performance of the wall. A typical residential 2 {times} 4 stud wall was constructed and placed on top of a subfloor, making a 2.44 {times} 2.74 m (8 by 9 ft) test specimen. This base wall assembly was then covered with two types of XPS sheathing, various housewraps, a 15{number_sign} felt, and a polyethylene vapor retarder film in 40 different configurations and tested individually per ASTM E 283 and per ASTM C 976. For 24 of themore » 40 C 976 tests, a differential pressure was induced across the test wall as per and ASTM E 1424. Airflows ranged from undetectable airflow at 0 {center_dot} Pa {Delta}P to 1.63 L/s {center_dot} m{sup 2} for the base wall assembly alone. Difference in airflow resistance performance between the ASTM E 283 and ASTM E 1424 test methods were noted. Thermal testing results incorporating both ASTM C 976 and ASTM E 1424 for tests 1--28 produced apparent thermal conductances (C-values) in the range of 0.40 W/m{sup 2} {center_dot} K for a nondetectable airflow level to 1.81 W/m{sup 2} {center_dot} K for an airflow of 1.53 L/s {center_dot} m{sup 2} for the base wall assembly alone with a 20-Pa {Delta}P. The calculated C-value for this base wall assembly was 0.40 W/m{sup 2} {center_dot} K. Test results reveal that airflow rates as low as 0.2 L/s {center_dot} m{sup 2} could produce a 46% increase in apparent C-value. Similar thermal performance differences were revealed when thicker shiplap XPS sheathing was used. Tests were also conducted using an Air-Tight Drywall configuration showing the effect of wind washing on thermal performance. By sealing the gypsum drywall on the base wall assembly tested, the apparent C-value, when exposed to a 12.5 Pa wind pressure, was found to be equivalent to a base wall assembly configuration which allows 0.15 L/s {center_dot} m{sup 2} airflow to penetrate completely through.« less

What is normal nasal airflow? A computational study of 22 healthy adults

PubMed Central

Zhao, Kai; Jiang, Jianbo

2014-01-01

Objective Nasal airflow is essential for functioning of the human nose. Given individual variation in nasal anatomy, there is yet no consensus what constitutes normal nasal airflow patterns. We attempt to obtain such information that is essential to differentiate disease-related variations. Methods Computational fluid dynamics (CFD) simulated nasal airflow in 22 healthy subjects during resting breathing. Streamline patterns, airflow distributions, velocity profiles, pressure, wall stress, turbulence, and vortical flow characteristics under quasi-steady state were analyzed. Patency ratings, acoustically measured minimum cross-sectional area (MCA), and rhinomanometric nasal resistance (NR) were examined for potential correlations with morphological and airflow-related variables. Results Common features across subjects included: >50% total pressure-drop reached near the inferior turbinate head; wall shear stress, NR, turbulence energy, and vorticity were lower in the turbinate than in the nasal valve region. However, location of the major flow path and coronal velocity distributions varied greatly across individuals. Surprisingly, on average, more flow passed through the middle than the inferior meatus and correlated with better patency ratings (r=-0.65, p<0.01). This middle flow percentage combined with peak post-vestibule nasal heat loss and MCA accounted for >70% of the variance in subjective patency ratings and predicted patency categories with 86% success. Nasal index correlated with forming of the anterior dorsal vortex. Expected for resting breathing, the functional impact for local and total turbulence, vorticity, and helicity was limited. As validation, rhinomanometric NR significantly correlated with CFD simulations (r=0.53, p<0.01). Conclusion Significant variations of nasal airflow found among healthy subjects; Key features may have clinically relevant applications. PMID:24664528

Airflow in Tracheobronchial Tree of Subjects with Tracheal Bronchus Simulated Using CT Image Based Models and CFD Method.

PubMed

Qi, Shouliang; Zhang, Baihua; Yue, Yong; Shen, Jing; Teng, Yueyang; Qian, Wei; Wu, Jianlin

2018-03-01

Tracheal Bronchus (TB) is a rare congenital anomaly characterized by the presence of an abnormal bronchus originating from the trachea or main bronchi and directed toward the upper lobe. The airflow pattern in tracheobronchial trees of TB subjects is critical, but has not been systemically studied. This study proposes to simulate the airflow using CT image based models and the computational fluid dynamics (CFD) method. Six TB subjects and three health controls (HC) are included. After the geometric model of tracheobronchial tree is extracted from CT images, the spatial distribution of velocity, wall pressure, wall shear stress (WSS) is obtained through CFD simulation, and the lobar distribution of air, flow pattern and global pressure drop are investigated. Compared with HC subjects, the main bronchus angle of TB subjects and the variation of volume are large, while the cross-sectional growth rate is small. High airflow velocity, wall pressure, and WSS are observed locally at the tracheal bronchus, but the global patterns of these measures are still similar to those of HC. The ratio of airflow into the tracheal bronchus accounts for 6.6-15.6% of the inhaled airflow, decreasing the ratio to the right upper lobe from 15.7-21.4% (HC) to 4.9-13.6%. The air into tracheal bronchus originates from the right dorsal near-wall region of the trachea. Tracheal bronchus does not change the global pressure drop which is dependent on multiple variables. Though the tracheobronchial trees of TB subjects present individualized features, several commonalities on the structural and airflow characteristics can be revealed. The observed local alternations might provide new insight into the reason of recurrent local infections, cough and acute respiratory distress related to TB.

Unidirectional pulmonary airflow patterns in the savannah monitor lizard.

PubMed

Schachner, Emma R; Cieri, Robert L; Butler, James P; Farmer, C G

2014-02-20

The unidirectional airflow patterns in the lungs of birds have long been considered a unique and specialized trait associated with the oxygen demands of flying, their endothermic metabolism and unusual pulmonary architecture. However, the discovery of similar flow patterns in the lungs of crocodilians indicates that this character is probably ancestral for all archosaurs--the group that includes extant birds and crocodilians as well as their extinct relatives, such as pterosaurs and dinosaurs. Unidirectional flow in birds results from aerodynamic valves, rather than from sphincters or other physical mechanisms, and similar aerodynamic valves seem to be present in crocodilians. The anatomical and developmental similarities in the primary and secondary bronchi of birds and crocodilians suggest that these structures and airflow patterns may be homologous. The origin of this pattern is at least as old as the split between crocodilians and birds, which occurred in the Triassic period. Alternatively, this pattern of flow may be even older; this hypothesis can be tested by investigating patterns of airflow in members of the outgroup to birds and crocodilians, the Lepidosauromorpha (tuatara, lizards and snakes). Here we demonstrate region-specific unidirectional airflow in the lungs of the savannah monitor lizard (Varanus exanthematicus). The presence of unidirectional flow in the lungs of V. exanthematicus thus gives rise to two possible evolutionary scenarios: either unidirectional airflow evolved independently in archosaurs and monitor lizards, or these flow patterns are homologous in archosaurs and V. exanthematicus, having evolved only once in ancestral diapsids (the clade encompassing snakes, lizards, crocodilians and birds). If unidirectional airflow is plesiomorphic for Diapsida, this respiratory character can be reconstructed for extinct diapsids, and evolved in a small ectothermic tetrapod during the Palaeozoic era at least a hundred million years before the origin of birds.

The Granite Mountain Atmospheric Sciences Testbed (GMAST): A Facility for Long Term Complex Terrain Airflow Studies

NASA Astrophysics Data System (ADS)

Zajic, D.; Pace, J. C.; Whiteman, C. D.; Hoch, S.

2011-12-01

This presentation describes a new facility at Dugway Proving Ground (DPG), Utah that can be used to study airflow over complex terrain, and to evaluate how airflow over a mountain barrier affects wind patterns over adjacent flatter terrain. DPG's primary mission is to conduct testing, training, and operational assessments of chemical and biological weapon systems. These operations require very precise weather forecasts. Most test operations at DPG are conducted on fairly flat test ranges having uniform surface cover, where airflow patterns are generally well-understood. However, the DPG test ranges are located alongside large, isolated mountains, most notably Granite Mountain, Camelback Mountain, and the Cedar Mountains. Airflows generated over, or influenced by, these mountains can affect wind patterns on the test ranges. The new facility, the Granite Mountain Atmospheric Sciences Testbed, or GMAST, is designed to facilitate studies of airflow interactions with topography. This facility will benefit DPG by improving understanding of how mountain airflows interact with the test range conditions. A core infrastructure of weather sensors around and on Granite Mountain has been developed including instrumented towers and remote sensors, along with automated data collection and archival systems. GMAST is expected to be in operation for a number of years and will provide a reference domain for mountain meteorology studies, with data useful for analysts, modelers and theoreticians. Visiting scientists are encouraged to collaborate with DPG personnel to utilize this valuable scientific resource and to add further equipment and scientific designs for both short-term and long-term atmospheric studies. Several of the upcoming MATERHORN (MountAin TERrain atmospHeric mOdeling and obseRvatioNs) project field tests will be conducted at DPG, giving an example of GMAST utilization and collaboration between DPG and visiting scientists.

How much does nasal cavity morphology matter? Patterns and rates of olfactory airflow in phyllostomid bats

PubMed Central

Eiting, Thomas P.; Perot, J. Blair; Dumont, Elizabeth R.

2015-01-01

The morphology of the nasal cavity in mammals with a good sense of smell includes features that are thought to improve olfactory airflow, such as a dorsal conduit that delivers odours quickly to the olfactory mucosa, an enlarged olfactory recess at the back of the airway, and a clear separation of the olfactory and respiratory regions of the nose. The link between these features and having a good sense of smell has been established by functional examinations of a handful of distantly related mammalian species. In this paper, we provide the first detailed examination of olfactory airflow in a group of closely related species that nevertheless vary in their sense of smell. We study six species of phyllostomid bats that have different airway morphologies and foraging ecologies, which have been linked to differences in olfactory ability or reliance. We hypothesize that differences in morphology correlate with differences in the patterns and rates of airflow, which in turn are consistent with dietary differences. To compare species, we make qualitative and quantitative comparisons of the patterns and rates of airflow through the olfactory region during both inhalation and exhalation across the six species. Contrary to our expectations, we find no clear differences among species in either the patterns of airflow through the airway or in rates of flow through the olfactory region. By and large, olfactory airflow seems to be conserved across species, suggesting that morphological differences appear to be driven by other mechanical demands on the snout, such as breathing and feeding. Olfactory ability may depend on other aspects of the system, such as the neurobiological processing of odours that work within the existing morphology imposed by other functional demands on the nasal cavity. PMID:25520358

Changes in aerodynamics during vocal cord dysfunction.

PubMed

Frank-Ito, Dennis O; Schulz, Kristine; Vess, Gina; Witsell, David L

2015-02-01

Changes in laryngeal airflow dynamics during episodes of vocal cord dysfunction (VCD) have not been well described. Very little is known about how inspiratory airflow is impacted when the vocal cords transition from normal inhalation state to a paradoxical adducted state; and how much change in laryngeal airflow and resistance occur before symptoms of stridor and air hunger emerge. This study provides new insight on the effects of VCD on respiratory airflow using computational fluid dynamics (CFD) techniques. Computed tomography images of a subject with normal vocal cords opening at the time of scanning were digitally modified to mimic an episode of VCD. To quantify and compare changes in inspiratory flow during VCD attack and normal inhalation, steady-state, laminar simulations were performed for three different breathing rates. Pressure-flow analysis during VCD revealed that increasing inspiratory effort is not as efficient as in normal inhalation. Airflow resistance at the epiglottis was higher in the normal state (0.04Pa.s/mL versus 0.02Pa.s/mL) than in VCD; while resistance at the glottis and trachea remained roughly the same (0.04Pa.s/mL) during normal inhalation, it escalated during VCD (0.11Pa.s/mL and 0.13Pa.s/mL at the glottis and trachea, respectively). Peak airflow velocity and vorticity occurred around the glottis during VCD, and at the epiglottis during normal inhalation. This pilot study demonstrates that attempting to force more inspired air will yield greater glottal resistance during VCD. Furthermore, there were evidence of abrupt laryngeal pressure gradient, chaotic airflow and high concentration of shear stresses in the glottal region. Copyright © 2014 Elsevier Ltd. All rights reserved.

Temperature-controlled airflow ventilation in operating rooms compared with laminar airflow and turbulent mixed airflow.

PubMed

Alsved, M; Civilis, A; Ekolind, P; Tammelin, A; Andersson, A Erichsen; Jakobsson, J; Svensson, T; Ramstorp, M; Sadrizadeh, S; Larsson, P-A; Bohgard, M; Šantl-Temkiv, T; Löndahl, J

2018-02-01

To evaluate three types of ventilation systems for operating rooms with respect to air cleanliness [in colony-forming units (cfu/m 3 )], energy consumption and comfort of working environment (noise and draught) as reported by surgical team members. Two commonly used ventilation systems, vertical laminar airflow (LAF) and turbulent mixed airflow (TMA), were compared with a newly developed ventilation technique, temperature-controlled airflow (T c AF). The cfu concentrations were measured at three locations in an operating room during 45 orthopaedic procedures: close to the wound (<40cm), at the instrument table and peripherally in the room. The operating team evaluated the comfort of the working environment by answering a questionnaire. LAF and T c AF, but not TMA, resulted in less than 10cfu/m 3 at all measurement locations in the room during surgery. Median values of cfu/m 3 close to the wound (250 samples) were 0 for LAF, 1 for T c AF and 10 for TMA. Peripherally in the room, the cfu concentrations were lowest for T c AF. The cfu concentrations did not scale proportionally with airflow rates. Compared with LAF, the power consumption of T c AF was 28% lower and there was significantly less disturbance from noise and draught. T c AF and LAF remove bacteria more efficiently from the air than TMA, especially close to the wound and at the instrument table. Like LAF, the new T c AF ventilation system maintained very low levels of cfu in the air, but T c AF used substantially less energy and provided a more comfortable working environment than LAF. This enables energy savings with preserved air quality. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Eyelashes divert airflow to protect the eye

PubMed Central

Amador, Guillermo J.; Mao, Wenbin; DeMercurio, Peter; Montero, Carmen; Clewis, Joel; Alexeev, Alexander; Hu, David L.

2015-01-01

Eyelashes are ubiquitous, although their function has long remained a mystery. In this study, we elucidate the aerodynamic benefits of eyelashes. Through anatomical measurements, we find that 22 species of mammals possess eyelashes of a length one-third the eye width. Wind tunnel experiments confirm that this optimal eyelash length reduces both deposition of airborne particles and evaporation of the tear film by a factor of two. Using scaling theory, we find this optimum arises because of the incoming flow's interactions with both the eye and eyelashes. Short eyelashes create a stagnation zone above the ocular surface that thickens the boundary layer, causing shear stress to decrease with increasing eyelash length. Long eyelashes channel flow towards the ocular surface, causing shear stress to increase with increasing eyelash length. These competing effects result in a minimum shear stress for intermediate eyelash lengths. This design may be employed in creating eyelash-inspired protection for optical sensors. PMID:25716186

Hydroclimate variability and regional atmospheric circulation over the past 1,350 years reconstructed from Lake Ohau, New Zealand

NASA Astrophysics Data System (ADS)

Roop, H. A.; Levy, R. H.; Vandergoes, M.; Dunbar, G. B.; Howarth, J. D.; Lorrey, A.; Phipps, S. J.

2016-12-01

Comprehensive understanding of natural climate-system dynamics requires high-resolution paleoclimate records extending beyond the instrumental period. This is particularly the case for the sparsely-instrumented Southern Hemisphere mid-latitudes, where the timing and amplitude of regional and hemispheric-scale climatic events are poorly constrained. Here we present a 1,350-year record of hydroclimatic variability and regional circulation derived from an annually laminated sediment record from Lake Ohau, South Island, New Zealand (44.23°S, 169.85°E). The climate of New Zealand is influenced by climatological patterns originating in both the tropics (e.g. El-Niño-Southern Oscillation, Interdecadal Pacific Oscillation) and the Antarctic (Southern Annular Mode, SAM). Utilizing the annually resolved Lake Ohau hydroclimate record in combination with a tree-ring record of summer temperature from Oroko Swamp, New Zealand (Cook et al., 2002), we generate a circulation index for the Western South Island of New Zealand. This index utilizes the temperature and precipitation anomalies defined by the Regional Climate Regime Classification scheme for New Zealand to assign synoptic scale circulation patterns to 25-year intervals from 900-2000 AD. This circulation index shows significant periods of change, most notably 835 - 985 AD when northerly airflow dominated and from 1385 - 1710 AD when strong southerly airflow persisted. Comparisons with regional SAM and ENSO reconstructions show that dry, warm conditions at Lake Ohau are consistently associated with strengthened tropical teleconnections to New Zealand and a positive SAM, while cold and wet conditions are driven by increased southerly airflow and negative phase SAM. A persistent negative SAM dominates the Little Ice Age (LIA; 1385-1710 AD) interval in the Western South Island. This same period coincides with the Northern Hemisphere LIA.

Changes in breathing pattern in the normal horse at rest up to age one year.

PubMed

Koterba, A M; Wozniak, J A; Kosch, P C

1995-07-01

Changes in pattern of airflow, sequence of respiratory muscle activation and generated pressures were measured serially in a group of foals during the first year post partum, in order to describe the maturation of the equine breathing pattern. In neonatal foals, inspiration and expiration were both primarily active and airflow pattern was essentially monophasic. By age 1 year, foals displayed essentially the same breathing pattern previously described in adult horses, utilising a combination of active and passive inspiration and expiration to breathe around, rather than from, the relaxation volume of the respiratory system (Vrx). A strong temporal relationship during growth was found between the timing of changes observed in airflow pattern and in the neuromuscular strategy of breathing. The transition to the adult breathing pattern appeared to involve a time delay in activation of both inspiratory and expiratory muscle groups, establishing a passive and active component to both inspiration and expiration. Throughout the study period, concurrent with the increase in delay of abdominal muscle activation, the expiratory flow pattern became progressively more biphasic in appearance. The time of appearance of a consistent biphasic inspiratory flow pattern was considerably later, at approximately age 1 year and coincided with the appearance of a delay in inspiratory muscle activation. From our results, we conclude that the transition from the neonatal to the adult breathing strategy in the horse appears not to be induced by the time course of chest wall stiffening during maturation. While changes in relative body proportions and size of abdominal contents during growth may influence the transition in breathing, our results also indicate that respiratory control mechanisms play an essential role in the expression of the polyphasic breathing pattern.

Chronic obstructive pulmonary disease mortality and prevalence: the associations with smoking and poverty--a BOLD analysis.

PubMed

Burney, Peter; Jithoo, Anamika; Kato, Bernet; Janson, Christer; Mannino, David; Nizankowska-Mogilnicka, Ewa; Studnicka, Michael; Tan, Wan; Bateman, Eric; Koçabas, Ali; Vollmer, William M; Gislason, Thorarrin; Marks, Guy; Koul, Parvaiz A; Harrabi, Imed; Gnatiuc, Louisa; Buist, Sonia

2014-05-01

Chronic obstructive pulmonary disease (COPD) is a commonly reported cause of death and associated with smoking. However, COPD mortality is high in poor countries with low smoking rates. Spirometric restriction predicts mortality better than airflow obstruction, suggesting that the prevalence of restriction could explain mortality rates attributed to COPD. We have studied associations between mortality from COPD and low lung function, and between both lung function and death rates and cigarette consumption and gross national income per capita (GNI). National COPD mortality rates were regressed against the prevalence of airflow obstruction and spirometric restriction in 22 Burden of Obstructive Lung Disease (BOLD) study sites and against GNI, and national smoking prevalence. The prevalence of airflow obstruction and spirometric restriction in the BOLD sites were regressed against GNI and mean pack years smoked. National COPD mortality rates were more strongly associated with spirometric restriction in the BOLD sites (<60 years: men rs=0.73, p=0.0001; women rs=0.90, p<0.0001; 60+ years: men rs=0.63, p=0.0022; women rs=0.37, p=0.1) than obstruction (<60 years: men rs=0.28, p=0.20; women rs=0.17, p<0.46; 60+ years: men rs=0.28, p=0.23; women rs=0.22, p=0.33). Obstruction increased with mean pack years smoked, but COPD mortality fell with increased cigarette consumption and rose rapidly as GNI fell below US$15 000. Prevalence of restriction was not associated with smoking but also increased rapidly as GNI fell below US$15 000. Smoking remains the single most important cause of obstruction but a high prevalence of restriction associated with poverty could explain the high 'COPD' mortality in poor countries.

Estimation of Pharyngeal Collapsibility During Sleep by Peak Inspiratory Airflow.

PubMed

Azarbarzin, Ali; Sands, Scott A; Taranto-Montemurro, Luigi; Oliveira Marques, Melania D; Genta, Pedro R; Edwards, Bradley A; Butler, James; White, David P; Wellman, Andrew

2017-01-01

Pharyngeal critical closing pressure (Pcrit) or collapsibility is a major determinant of obstructive sleep apnea (OSA) and may be used to predict the success/failure of non-continuous positive airway pressure (CPAP) therapies. Since its assessment involves overnight manipulation of CPAP, we sought to validate the peak inspiratory flow during natural sleep (without CPAP) as a simple surrogate measurement of collapsibility. Fourteen patients with OSA attended overnight polysomnography with pneumotachograph airflow. The middle third of the night (non-rapid eye movement sleep [NREM]) was dedicated to assessing Pcrit in passive and active states via abrupt and gradual CPAP pressure drops, respectively. Pcrit is the extrapolated CPAP pressure at which flow is zero. Peak and mid-inspiratory flow off CPAP was obtained from all breaths during sleep (excluding arousal) and compared with Pcrit. Active Pcrit, measured during NREM sleep, was strongly correlated with both peak and mid-inspiratory flow during NREM sleep (r = -0.71, p < .005 and r = -0.64, p < .05, respectively), indicating that active pharyngeal collapsibility can be reliably estimated from simple airflow measurements during polysomnography. However, there was no significant relationship between passive Pcrit, measured during NREM sleep, and peak or mid-inspiratory flow obtained from NREM sleep. Flow measurements during REM sleep were not significantly associated with active or passive Pcrit. Our study demonstrates the feasibility of estimating active Pcrit using flow measurements in patients with OSA. This method may enable clinicians to estimate pharyngeal collapsibility without sophisticated equipment and potentially aid in the selection of patients for non- positive airway pressure therapies. © Sleep Research Society 2016. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corley, Richard A; Minard, Kevin R; Kabilan, Senthil

The percentages of total airflows over the nasal respiratory and olfactory epithelium of female rabbits were calculated from computational fluid dynamics (CFD) simulations of steady-state inhalation. These airflows calculations, along with nasal airway geometry determinations, are critical parameters for hybrid CFD/physiologically based pharmacokinetic models that describe the nasal dosimetry of water-soluble or reactive gases and vapors in rabbits. CFD simulations were based upon three-dimensional computational meshes derived from magnetic resonance images of three adult female New Zealand White (NZW) rabbits. In the anterior portion of the nose, the maxillary turbinates of rabbits are considerably more complex than comparable regions inmore » rats, mice, monkeys, or humans. This leads to a greater surface area to volume ratio in this region and thus the potential for increased extraction of water soluble or reactive gases and vapors in the anterior portion of the nose compared to many other species. Although there was considerable interanimal variability in the fine structures of the nasal turbinates and airflows in the anterior portions of the nose, there was remarkable consistency between rabbits in the percentage of total inspired airflows that reached the ethmoid turbinate region (~50%) that is presumably lined with olfactory epithelium. These latter results (airflows reaching the ethmoid turbinate region) were higher than previous published estimates for the male F344 rat (19%) and human (7%). These differences in regional airflows can have significant implications in interspecies extrapolations of nasal dosimetry.« less

Wind observations above an urban river using a new lidar technique, scintillometry and anemometry.

PubMed

Wood, C R; Pauscher, L; Ward, H C; Kotthaus, S; Barlow, J F; Gouvea, M; Lane, S E; Grimmond, C S B

2013-01-01

Airflow along rivers might provide a key mechanism for ventilation in cities: important for air quality and thermal comfort. Airflow varies in space and time in the vicinity of rivers. Consequently, there is limited utility in point measurements. Ground-based remote sensing offers the opportunity to study 3D airflow in locations which are difficult to observe with conventional approaches. For three months in the winter and spring of 2011, the airflow above the River Thames in central London was observed using a scanning Doppler lidar, a scintillometer and sonic anemometers. First, an inter-comparison showed that lidar-derived mean wind-speed estimates compare almost as well to sonic anemometers (root-mean-square error (rmse) 0.65-0.68 ms(-1)) as comparisons between sonic anemometers (0.35-0.73 ms(-1)). Second, the lidar duo-beam operating strategy provided horizontal transects of wind vectors (comparison with scintillometer rmse 1.12-1.63 ms(-1)) which revealed mean and turbulent airflow across the river and surrounds; in particular, channelled airflow along the river and changes in turbulence quantities consistent with the roughness changes between built and river environments. The results have important consequences for air quality and dispersion around urban rivers, especially given that many cities have high traffic rates on roads located on riverbanks. Copyright © 2012 Elsevier B.V. All rights reserved.

Respiration and heartbeat signal detection from airflow at airway in rat by catheter flow sensor with temperature compensation function

NASA Astrophysics Data System (ADS)

Hasegawa, Y.; Kawaoka, H.; Yamada, T.; Matsushima, M.; Kawabe, T.; Shikida, M.

2017-12-01

We previously proposed an evaluation method for detecting both respiration and heartbeat signals from the airflow at the mouth (Kawaoka et al 201518th Int. Conf. on Solid-State Sensors, Actuators and Microsystems; Kawaoka et al 2015 IEEE Sensors; Kawaoka et al 2016 Technical Digest IEEE Micro Electro Mechanical Systems Conf.). In the current study, we developed a catheter flow sensor with temperature compensation that uses MEMS technologies and used it to directly detect the breathing airflow in the airway of a rat. The temperature sensors were integrated with the catheter flow sensor. Heaters working as airflow and temperature sensors were produced on polymer film by using the same fabrication process so that the temperature coefficients of their resistances would coincide. As a result, the variation in sensor outputs due to the airflow temperature changes ranging from 20 °C to 34 °C was suppressed to less than 2.5%. The developed catheter flow sensor was inserted into the airway of a rat to detect both respiration and heartbeat signals. The accuracy of the breathing airflow measurements was improved thanks to the temperature compensation. The tidal volume variations between the expired and inspired air were suppressed to within 5%. Heartbeat signal information was extracted from the measured breathing waveforms by applying a discrete Fourier transform.

Adult normative data for phonatory aerodynamics in connected speech.

PubMed

Lewandowski, Ali; Gillespie, Amanda I; Kridgen, Samantha; Jeong, Kwonho; Yu, Lan; Gartner-Schmidt, Jackie

2018-04-01

To establish normative values for phonatory aerodynamic measurements in connected speech across adult ages and gender. Prospective data collection across group design. One hundred fifty adults aged >18 years without voice complaints were stratified into three equal-age groups (group 1 [ages 18-39 years]; group 2 [ages 40-59 years], and group 3 [ages 60 + years]) and two equal-gender groups (male and female) resulting in 25 participants in each category. Participants read the first four sentences of the Rainbow Passage at comfortable pitch and loudness to obtain a connected speech sample. The following dependent variables were analyzed: breath number, reading passage duration, mean phonatory airflow, inspiratory airflow duration, and expiratory airflow duration. A gender effect was found for mean phonatory airflow, with males showing significantly greater phonatory airflow than females during connected speech (P < .001). Number of breaths was significantly greater for group 3 than group 2 (P < .001) and group 1 (P < .001). Duration, and inspiratory and expiratory airflow durations were all significantly greater for group 3 (P < .001) than group 2 (P < .001) than group 1 (P < .001). This study provides normative data for phonatory aerodynamics in adult connected speech. Significant age and gender effects were observed. Laryngoscope, 128:909-914, 2018. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

Fine-scale flight strategies of gulls in urban airflows indicate risk and reward in city living

PubMed Central

Shepard, Emily L. C.

2016-01-01

Birds modulate their flight paths in relation to regional and global airflows in order to reduce their travel costs. Birds should also respond to fine-scale airflows, although the incidence and value of this remains largely unknown. We resolved the three-dimensional trajectories of gulls flying along a built-up coastline, and used computational fluid dynamic models to examine how gulls reacted to airflows around buildings. Birds systematically altered their flight trajectories with wind conditions to exploit updraughts over features as small as a row of low-rise buildings. This provides the first evidence that human activities can change patterns of space-use in flying birds by altering the profitability of the airscape. At finer scales still, gulls varied their position to select a narrow range of updraught values, rather than exploiting the strongest updraughts available, and their precise positions were consistent with a strategy to increase their velocity control in gusty conditions. Ultimately, strategies such as these could help unmanned aerial vehicles negotiate complex airflows. Overall, airflows around fine-scale features have profound implications for flight control and energy use, and consideration of this could lead to a paradigm-shift in the way ecologists view the urban environment. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’. PMID:27528784

Impacts of Fluid Dynamics Simulation in Study of Nasal Airflow Physiology and Pathophysiology in Realistic Human Three-Dimensional Nose Models

PubMed Central

Lee, Heow Peuh; Gordon, Bruce R.

2012-01-01

During the past decades, numerous computational fluid dynamics (CFD) studies, constructed from CT or MRI images, have simulated human nasal models. As compared to rhinomanometry and acoustic rhinometry, which provide quantitative information only of nasal airflow, resistance, and cross sectional areas, CFD enables additional measurements of airflow passing through the nasal cavity that help visualize the physiologic impact of alterations in intranasal structures. Therefore, it becomes possible to quantitatively measure, and visually appreciate, the airflow pattern (laminar or turbulent), velocity, pressure, wall shear stress, particle deposition, and temperature changes at different flow rates, in different parts of the nasal cavity. The effects of both existing anatomical factors, as well as post-operative changes, can be assessed. With recent improvements in CFD technology and computing power, there is a promising future for CFD to become a useful tool in planning, predicting, and evaluating outcomes of nasal surgery. This review discusses the possibilities and potential impacts, as well as technical limitations, of using CFD simulation to better understand nasal airflow physiology. PMID:23205221

Phase-Contrast MRI and CFD Modeling of Apparent 3He Gas Flow in Rat Pulmonary Airways

PubMed Central

Minard, Kevin R.; Kuprat, Andrew P.; Kabilan, Senthil; Jacob, Richard E.; Einstein, Daniel R.; Carson, James P.; Corley, Richard A.

2012-01-01

Phase-contrast (PC) magnetic resonance imaging (MRI) with hyperpolarized 3He is potentially useful for developing and testing patient-specific models of pulmonary airflow. One challenge, however, is that PC-MRI provides apparent values of local 3He velocity that not only depend on actual airflow but also on gas diffusion. This not only blurs laminar flow patterns in narrow airways but also introduces anomalous airflow structure that reflects gas-wall interactions. Here, both effects are predicted in a live rat using computational fluid dynamics (CFD), and for the first time, simulated patterns of apparent 3He gas velocity are compared with in-vivo PC-MRI. Results show 1) that correlations (R2) between measured and simulated airflow patterns increase from 0.23 to 0.79 simply by accounting for apparent 3He transport, and 2) that remaining differences are mainly due to uncertain airway segmentation and partial volume effects stemming from relatively coarse MRI resolution. Higher-fidelity testing of pulmonary airflow predictions should therefore be possible with future imaging improvements. PMID:22771528

Study on airflow characteristics in the semi-closed irregular narrow flow channel

NASA Astrophysics Data System (ADS)

Jin, Yuzhen; Hu, Xiaodong; Zhu, Linhang; Hu, Xudong; Jin, Yingzi

2016-04-01

The air-jet loom is widely used in the textile industry. The interaction mechanism of airflow and yarn is not clear in such a narrow flow channel, the gas consumption is relatively large, the yarn motion is unstable and the weft insertion is often interrupted during the operation. In order to study the characteristics of the semi-closed flow field in profiled dents, the momentum conservation equation is modified and the model parameters and boundary conditions are set. Compared with the different r, the ratio of profiled dent's thickness and gap, the results show that the smaller the r is, the smaller the velocity fluctuations of the airflow is. When the angle of profiled dents α is close to zero, the diffusion of the airflow will be less. The experiment is also conducted to verify the result of the simulation with a high-speed camera and pressure sensor in profiled dents. The airflow characteristics in the semi-closed irregular narrow flow channel in the paper would provide the theoretical basis for optimizing the weft insertion process of the air-jet loom.

Phase-contrast MRI and CFD modeling of apparent 3He gas flow in rat pulmonary airways

NASA Astrophysics Data System (ADS)

Minard, Kevin R.; Kuprat, Andrew P.; Kabilan, Senthil; Jacob, Richard E.; Einstein, Daniel R.; Carson, James P.; Corley, Richard A.

2012-08-01

Phase-contrast (PC) magnetic resonance imaging (MRI) with hyperpolarized 3He is potentially useful for developing and testing patient-specific models of pulmonary airflow. One challenge, however, is that PC-MRI provides apparent values of local 3He velocity that not only depend on actual airflow but also on gas diffusion. This not only blurs laminar flow patterns in narrow airways but also introduces anomalous airflow structure that reflects gas-wall interactions. Here, both effects are predicted in a live rat using computational fluid dynamics (CFD), and for the first time, simulated patterns of apparent 3He gas velocity are compared with in vivo PC-MRI. Results show (1) that correlations (R2) between measured and simulated airflow patterns increase from 0.23 to 0.79 simply by accounting for apparent 3He transport, and (2) that remaining differences are mainly due to uncertain airway segmentation and partial volume effects stemming from relatively coarse MRI resolution. Higher-fidelity testing of pulmonary airflow predictions should therefore be possible with future imaging improvements.

Control method for turbocharged diesel engines having exhaust gas recirculation

DOEpatents

Kolmanovsky, Ilya V.; Jankovic, Mrdjan J; Jankovic, Miroslava

2000-03-14

A method of controlling the airflow into a compression ignition engine having an EGR and a VGT. The control strategy includes the steps of generating desired EGR and VGT turbine mass flow rates as a function of the desired and measured compressor mass airflow values and exhaust manifold pressure values. The desired compressor mass airflow and exhaust manifold pressure values are generated as a function of the operator-requested fueling rate and engine speed. The EGR and VGT turbine mass flow rates are then inverted to corresponding EGR and VGT actuator positions to achieve the desired compressor mass airflow rate and exhaust manifold pressure. The control strategy also includes a method of estimating the intake manifold pressure used in generating the EGR valve and VGT turbine positions.

Poppet valve control of throat stability bypass to increase stable airflow range of a Mach 2.5. inlet with 60 percent internal contraction

NASA Technical Reports Server (NTRS)

Mitchell, G. A.; Sanders, B. W.

1975-01-01

The throat of a Mach 2.5 inlet with a coldpipe termination was fitted with a stability-bypass system. System variations included several stability bypass entrance configurations. Poppet valves controlled the bypass airflow. The inlet stable airflow range achieved with each configuration was determined for both steady state conditions and internal pulse transients. Results are compared with those obtained without a stability bypass system. Transient results were also obtained for the inlet with a choke point at the diffuser exit and for the inlet with large and small stability bypass plenum volumes. Poppet valves at the stability bypass exit provided the inlet with a stable airflow range of 20 percent or greater at all static and transient conditions.

Insects have hairy eyes that reduce particle deposition

NASA Astrophysics Data System (ADS)

Amador, G. J.; Durand, F.; Mao, W.; Pusulri, S.; Takahashi, H.; Nguyen, V.-T.; Shimoyama, I.; Alexeev, A.; Hu, D. L.

2015-12-01

An insect's eyes may make up to 40% of its body's surface, and are in danger of being coated by foreign particles such as dust and pollen. To protect them, several insect species possess an array of ocular hairs evenly spaced between each photoreceptor unit. Although these hairs have been observed for over 50 years, their purpose remains a mystery. In this study, we elucidate the function of ocular hairs using a combination of experiments, numerical simulation and micro-fabrication. We measure the eyes of 18 species of insects and find that the length of their ocular hairs is equal to their spacing. We conduct wind tunnel experiments using both an insect eye mimic and an at-scale fabricated micro-pillar array of the same dimensions as the insect eye. Our experiments and simulations show that ocular hairs reduce airflow at the eye surface by up to 90%. We conclude that ocular hairs act similarly to mammalian eyelashes: as insects fly, ocular hairs deflect incoming air and create a zone of stagnant air. Airflow and particle deposition are reduced dramatically, while light is only minimally occluded. Micro-scale ocular hairs may find application in the deployment of sensors outdoors, for which accumulation of airborne dust and pollen has no current solution.

Wind-Driven Natural Ventilation Design Of Walk-Up Apartment In Coastal Region North Jakarta

NASA Astrophysics Data System (ADS)

Nugrahanti, Fathina I.; Yasin, P. E.; Nurdini, A.

2018-05-01

Housing has been the second most energy-consuming sector in Indonesia nowadays. According to the data released by government, the biggest consumption in housing sector is the use of air conditioning. This consumption will significantly rise in metropolitan-high density city like Jakarta along with the increase of vertical housing supply. This research focus on design iteration to achieve optimum model of wind-driven naturally ventilated housing. Cilincing District, North Jakarta, known as industrial and settlement area is used as case study. Since the location by the bay area, Cilincing represents the characteristic of tropical coastal area. This research utilizes the tropical coastal characteristic especially wind to design a naturally ventilated housing. Various building elements are determined as variables and tested using Ansys Fluent CFD simulator to achieve thermal comfort stadard by SNI 03-6572-2001. Preliminary results shows that unlinear (zig-zag) building layout and combination of various building distances give big impact to airflow movement around the buildings. Narrowing building distance in the middle of the site can create a kind-of tunnel / trap that strengthen the wind along the site. Inlet and outlet area should be balance to avoid uneven airflow distribution inside the room and located in different level to maximize cross-ventilation.

Methods to reduce the CO(2) concentration of educational buildings utilizing internal ventilation by transferred air.

PubMed

Kalema, T; Viot, M

2014-02-01

The aim of this study is to develop internal ventilation by transferred air to achieve a good indoor climate with low energy consumption in educational buildings with constant air volume (CAV) ventilation. Both measurements of CO2 concentration and a multi-room calculation model are presented. The study analyzes how to use more efficiently the available spaces and the capacity of CAV ventilation systems in existing buildings and the impact this has on the indoor air quality and the energy consumption of the ventilation. The temperature differences can be used to create natural ventilation airflows between neighboring spaces. The behavior of temperature-driven airflows between rooms was studied and included in the calculation model. The effect of openings between neighboring spaces, such as doors or large apertures in the walls, on the CO2 concentration was studied in different classrooms. The air temperatures and CO2 concentrations were measured using a wireless, internet-based measurement system. The multi-room calculation model predicted the CO2 concentration in the rooms, which was then compared with the measured ones. Using transferred air between occupied and unoccupied spaces can noticeably reduce the total mechanical ventilation rates needed to keep a low CO2 concentration. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Influence of bronchial diameter change on the airflow dynamics based on a pressure-controlled ventilation system.

PubMed

Ren, Shuai; Cai, Maolin; Shi, Yan; Xu, Weiqing; Zhang, Xiaohua Douglas

2018-03-01

Bronchial diameter is a key parameter that affects the respiratory treatment of mechanically ventilated patients. In this paper, to reveal the influence of bronchial diameter on the airflow dynamics of pressure-controlled mechanically ventilated patients, a new respiratory system model is presented that combines multigeneration airways with lungs. Furthermore, experiments and simulation studies to verify the model are performed. Finally, through the simulation study, it can be determined that in airway generations 2 to 7, when the diameter is reduced to half of the original value, the maximum air pressure (maximum air pressure in lungs) decreases by nearly 16%, the maximum flow decreases by nearly 30%, and the total airway pressure loss (sum of each generation pressure drop) is more than 5 times the original value. Moreover, in airway generations 8 to 16, with increasing diameter, the maximum air pressure, maximum flow, and total airway pressure loss remain almost constant. When the diameter is reduced to half of the original value, the maximum air pressure decreases by 3%, the maximum flow decreases by nearly 5%, and the total airway pressure loss increases by 200%. The study creates a foundation for improvement in respiratory disease diagnosis and treatment. Copyright © 2017 John Wiley & Sons, Ltd.

Perception of Better Nasal Patency Correlates with Increased Mucosal Cooling after Surgery for Nasal Obstruction

NASA Astrophysics Data System (ADS)

Garcia, Guilherme; Sullivan, Corbin; Frank-Ito, Dennis; Kimbell, Julia; Rhee, John

2014-11-01

Nasal airway obstruction (NAO) is a common health problem with 340,000 patients undergoing surgery annually in the United States. Traditionally, otolaryngologists have focused on airspace cross-sectional areas and nasal resistance to airflow as objective measures of nasal patency, but neither of these variables correlated consistently with patients' symptoms. Given that the sensation of nasal airflow is also associated with mucosal cooling (i.e., heat loss) during inspiration, we investigated the correlation between the sensation of nasal obstruction and mucosal cooling in 10 patients before and after NAO surgery. Three-dimensional models of the nasal anatomy were created based on pre- and post-surgery computed tomography scans. Computational fluid dynamics (CFD) simulations were conducted to quantify nasal resistance and mucosal cooling. Patient-reported symptoms were measured by a visual analog scale and the Nasal Obstruction Symptom Evaluation (NOSE), a disease-specific quality of life questionnaire. Our results revealed that the subjective sensation of nasal obstruction correlated with both nasal resistance and heat loss, but the strongest correlation was between the NOSE score and the nasal surface area where heat flux exceeds 50 W /m2 . In conclusion, a significant post-operative increase in mucosal cooling correlates well with patients' perception of better nasal patency after NAO surgery.

Numerical simulation of airflow around the evaporator in the closed space

NASA Astrophysics Data System (ADS)

Puchor, Tomáš; Banovčan, Roman; Lenhard, Richard

2018-06-01

The article deals with a numerical simulation of the forced airflow around a evaporator with the finned tubes in the electrotechnical box, by finite volume method in the program ANSYS Workbench. The work contains an analysis of the impact of forced airflow on the evaporator with the various seated the electrical components. The aim of the work is to find out the most effective way of heat dissipation by forced convection from the electrical components in the closed space with lowest pressure loss.

Computational studies of an intake manifold for restricted engine application

NASA Astrophysics Data System (ADS)

Prasetyo, Bagus Dwi; Ubaidillah, Maharani, Elliza Tri; Setyohandoko, Gabriel; Idris, Muhammad Idzdihar

2018-02-01

The Formula Society of Automotive Engineer (FSAE) student competition is an international contest for a vehicle that entirely designed and built by students from various universities. The engine design in the Formula SAE competition has to comply a tight regulation. Concerning the engine intake line, an air restrictor of circular cross-section less than 20 mm must be fitted between the throttle valve and the engine inlet. The throat is aimed to limit the engine air flow rate as it strongly influences the volumetric efficiency and then the maximum power. This article focuses on the design of the engine intake system of the Bengawan FSAE team vehicle to optimize the engine power output and its stability. The performance of engine intake system is studied through computational fluid dynamics (CFD). The objective of CFD is to know the pressure, velocity, and airflow of the air intake manifold for the best performance of the engine. The three-dimensional drawing of the intake manifold was made, and CFD simulation was conducted using ANSYS FLUENT. Two models were studied. The result shows that the different design produces a different value of the velocity of airflow and the kind of flow type.

Computational Fluid Dynamics Ventilation Study for the Human Powered Centrifuge at the International Space Station

NASA Technical Reports Server (NTRS)

Son, Chang H.

2012-01-01

The Human Powered Centrifuge (HPC) is a facility that is planned to be installed on board the International Space Station (ISS) to enable crew exercises under the artificial gravity conditions. The HPC equipment includes a "bicycle" for long-term exercises of a crewmember that provides power for rotation of HPC at a speed of 30 rpm. The crewmember exercising vigorously on the centrifuge generates the amount of carbon dioxide of about two times higher than a crewmember in ordinary conditions. The goal of the study is to analyze the airflow and carbon dioxide distribution within Pressurized Multipurpose Module (PMM) cabin when HPC is operating. A full unsteady formulation is used for airflow and CO2 transport CFD-based modeling with the so-called sliding mesh concept when the HPC equipment with the adjacent Bay 4 cabin volume is considered in the rotating reference frame while the rest of the cabin volume is considered in the stationary reference frame. The rotating part of the computational domain includes also a human body model. Localized effects of carbon dioxide dispersion are examined. Strong influence of the rotating HPC equipment on the CO2 distribution detected is discussed.

Flexible Micropost Arrays for Shear Stress Measurement

NASA Technical Reports Server (NTRS)

Wohl, Christopher J.; Palmieri, Frank L.; Hopkins, John W.; Jackson, Allen M.; Connell, John W.; Lin, Yi; Cisotto, Alexxandra A.

2015-01-01

Increased fuel costs, heightened environmental protection requirements, and noise abatement continue to place drag reduction at the forefront of aerospace research priorities. Unfortunately, shortfalls still exist in the fundamental understanding of boundary-layer airflow over aerodynamic surfaces, especially regarding drag arising from skin friction. For example, there is insufficient availability of instrumentation to adequately characterize complex flows with strong pressure gradients, heat transfer, wall mass flux, three-dimensionality, separation, shock waves, and transient phenomena. One example is the acoustic liner efficacy on aircraft engine nacelle walls. Active measurement of shear stress in boundary layer airflow would enable a better understanding of how aircraft structure and flight dynamics affect skin friction. Current shear stress measurement techniques suffer from reliability, complexity, and airflow disruption, thereby compromising resultant shear stress data. The state-of-the-art for shear stress sensing uses indirect or direct measurement techniques. Indirect measurements (e.g., hot-wire, heat flux gages, oil interferometry, laser Doppler anemometry, small scale pressure drag surfaces, i.e., fences) require intricate knowledge of the studied flow, restrictive instrument arrangements, large surface areas, flow disruption, or seeding material; with smaller, higher bandwidth probes under development. Direct measurements involve strain displacement of a sensor element and require no prior knowledge of the flow. Unfortunately, conventional "floating" recessed components for direct measurements are mm to cm in size. Whispering gallery mode devices and Fiber Bragg Gratings are examples of recent additions to this type of sensor with much smaller (?m) sensor components. Direct detection techniques are often single point measurements and difficult to calibrate and implement in wind tunnel experiments. In addition, the wiring, packaging, and installation of delicate micro-electromechanical devices impede the use of most direct shear sensors. Similarly, the cavity required for sensing element displacement is sensitive to particulate obstruction. This work was focused on developing a shear stress sensor for use in subsonic wind tunnel test facilities applicable to an array of test configurations. The non-displacement shear sensors described here have minimal packaging requirements resulting in minimal or no disturbance of boundary layer flow. Compared to previous concepts, device installation could be simple with reduced cost and down-time. The novelty lies in the creation of low profile (nanoscale to 100 µm) micropost arrays that stay within the viscous sub-layer of the airflow. Aerodynamic forces, which are related to the surface shear stress, cause post deflection and optical property changes. Ultimately, a reliable, accurate shear stress sensor that does not disrupt the airflow has the potential to provide high value data for flow physics researchers, aerodynamicists, and aircraft manufacturers leading to greater flight efficiency arising from more in-depth knowledge on how aircraft design impacts near surface properties.

An updated model of induced airflow in the unsaturated zone

USGS Publications Warehouse

Baehr, Arthur L.; Joss, Craig J.

1995-01-01

Simulation of induced movement of air in the unsaturated zone provides a method to determine permeability and to design vapor extraction remediation systems. A previously published solution to the airflow equation for the case in which the unsaturated zone is separated from the atmosphere by a layer of lower permeability (such as a clay layer) has been superseded. The new solution simulates airflow through the layer of lower permeability more rigorously by defining the leakage in terms of the upper boundary condition rather than by adding a leakage term to the governing airflow equation. This note presents the derivation of the new solution. Formulas for steady state pressure, specific discharge, and mass flow in the domain are obtained for the new model and for the case in which the unsaturated zone is in direct contact with the atmosphere.

A general introduction to aeroacoustics and atmospheric sound

NASA Technical Reports Server (NTRS)

Lighthill, James

1992-01-01

A single unifying principle (based upon the nonlinear 'momentum-flux' effects produced when different components of a motion transport different components of its momentum) is used to give a broad scientific background to several aspects of the interaction between airflows and atmospheric sound. First, it treats the generation of sound by airflows of many different types. These include, for example, jet-like flows involving convected turbulent motions (with the resulting aeroacoustic radiation sensitively dependent on the Mach number of convection) and they include, as an extreme case, the supersonic 'boom' (shock waves generated by a supersonically convected flow pattern). Next, an analysis is given of sound propagation through nonuniformly moving airflows, and the exchange is quantified of energy between flow and sound; while, finally, problems are examined of how sound waves 'on their own' may generate the airflows known as acoustic streaming.

Respiration detection chip with integrated temperature-insensitive MEMS sensors and CMOS signal processing circuits.

PubMed

Wei, Chia-Ling; Lin, Yu-Chen; Chen, Tse-An; Lin, Ren-Yi; Liu, Tin-Hao

2015-02-01

An airflow sensing chip, which integrates MEMS sensors with their CMOS signal processing circuits into a single chip, is proposed for respiration detection. Three micro-cantilever-based airflow sensors were designed and fabricated using a 0.35 μm CMOS/MEMS 2P4M mixed-signal polycide process. Two main differences were present among these three designs: they were either metal-covered or metal-free structures, and had either bridge-type or fixed-type reference resistors. The performances of these sensors were measured and compared, including temperature sensitivity and airflow sensitivity. Based on the measured results, the metal-free structure with fixed-type reference resistors is recommended for use, because it has the highest airflow sensitivity and also can effectively reduce the output voltage drift caused by temperature change.

Fluid structure interaction simulations of the upper airway in obstructive sleep apnea patients before and after maxillomandibular advancement surgery.

PubMed

Chang, Kwang K; Kim, Ki Beom; McQuilling, Mark W; Movahed, Reza

2018-06-01

The purpose of this study was to analyze pharyngeal airflow using both computational fluid dynamics (CFD) and fluid structure interactions (FSI) in obstructive sleep apnea patients before and after maxillomandibular advancement (MMA) surgery. The airflow characteristics before and after surgery were compared with both CFD and FSI. In addition, the presurgery and postsurgery deformations of the airway were evaluated using FSI. Digitized pharyngeal airway models of 2 obstructive sleep apnea patients were generated from cone-beam computed tomography scans before and after MMA surgery. CFD and FSI were used to evaluate the pharyngeal airflow at a maximum inspiration rate of 166 ml per second. Standard steady-state numeric formulations were used for airflow simulations. Airway volume increased, pressure drop decreased, maximum airflow velocity decreased, and airway resistance dropped for both patients after the MMA surgery. These findings occurred in both the CFD and FSI simulations. The FSI simulations showed an area of marked airway deformation in both patients before surgery, but this deformation was negligible after surgery for both patients. Both CFD and FSI simulations produced airflow results that indicated less effort was needed to breathe after MMA surgery. The FSI simulations demonstrated a substantial decrease in airway deformation after surgery. These beneficial changes positively correlated with the large improvements in polysomnography outcomes after MMA surgery. Copyright © 2018 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Changes in nasal airflow and heat transfer correlate with symptom improvement after surgery for nasal obstruction.

PubMed

Kimbell, J S; Frank, D O; Laud, Purushottam; Garcia, G J M; Rhee, J S

2013-10-18

Surgeries to correct nasal airway obstruction (NAO) often have less than desirable outcomes, partly due to the absence of an objective tool to select the most appropriate surgical approach for each patient. Computational fluid dynamics (CFD) models can be used to investigate nasal airflow, but variables need to be identified that can detect surgical changes and correlate with patient symptoms. CFD models were constructed from pre- and post-surgery computed tomography scans for 10 NAO patients showing no evidence of nasal cycling. Steady-state inspiratory airflow, nasal resistance, wall shear stress, and heat flux were computed for the main nasal cavity from nostrils to posterior nasal septum both bilaterally and unilaterally. Paired t-tests indicated that all CFD variables were significantly changed by surgery when calculated on the most obstructed side, and that airflow, nasal resistance, and heat flux were significantly changed bilaterally as well. Moderate linear correlations with patient-reported symptoms were found for airflow, heat flux, unilateral allocation of airflow, and unilateral nasal resistance as a fraction of bilateral nasal resistance when calculated on the most obstructed nasal side, suggesting that these variables may be useful for evaluating the efficacy of nasal surgery objectively. Similarity in the strengths of these correlations suggests that patient-reported symptoms may represent a constellation of effects and that these variables should be tracked concurrently during future virtual surgery planning. © 2013 Elsevier Ltd. All rights reserved.

The fluid dynamics of canine olfaction: unique nasal airflow patterns as an explanation of macrosmia

PubMed Central

Craven, Brent A.; Paterson, Eric G.; Settles, Gary S.

2010-01-01

The canine nasal cavity contains hundreds of millions of sensory neurons, located in the olfactory epithelium that lines convoluted nasal turbinates recessed in the rear of the nose. Traditional explanations for canine olfactory acuity, which include large sensory organ size and receptor gene repertoire, overlook the fluid dynamics of odorant transport during sniffing. But odorant transport to the sensory part of the nose is the first critical step in olfaction. Here we report new experimental data on canine sniffing and demonstrate allometric scaling of sniff frequency, inspiratory airflow rate and tidal volume with body mass. Next, a computational fluid dynamics simulation of airflow in an anatomically accurate three-dimensional model of the canine nasal cavity, reconstructed from high-resolution magnetic resonance imaging scans, reveals that, during sniffing, spatially separate odour samples are acquired by each nostril that may be used for bilateral stimulus intensity comparison and odour source localization. Inside the nose, the computation shows that a unique nasal airflow pattern develops during sniffing, which is optimized for odorant transport to the olfactory part of the nose. These results contrast sharply with nasal airflow in the human. We propose that mammalian olfactory function and acuity may largely depend on odorant transport by nasal airflow patterns resulting from either the presence of a highly developed olfactory recess (in macrosmats such as the canine) or the lack of one (in microsmats including humans). PMID:20007171

Air-flow regulation system for a coal gasifier

DOEpatents

Fasching, George E.

1984-01-01

An improved air-flow regulator for a fixed-bed coal gasifier is provided which allows close air-flow regulation from a compressor source even though the pressure variations are too rapid for a single primary control loop to respond. The improved system includes a primary controller to control a valve in the main (large) air supply line to regulate large slow changes in flow. A secondary controller is used to control a smaller, faster acting valve in a secondary (small) air supply line parallel to the main line valve to regulate rapid cyclic deviations in air flow. A low-pass filter with a time constant of from 20 to 50 seconds couples the output of the secondary controller to the input of the primary controller so that the primary controller only responds to slow changes in the air-flow rate, the faster, cyclic deviations in flow rate sensed and corrected by the secondary controller loop do not reach the primary controller due to the high frequency rejection provided by the filter. This control arrangement provides at least a factor of 5 improvement in air-flow regulation for a coal gasifier in which air is supplied by a reciprocating compressor through a surge tank.

Computational and experimental study of airflow around a fan powered UVGI lamp

NASA Astrophysics Data System (ADS)

Kaligotla, Srikar; Tavakoli, Behtash; Glauser, Mark; Ahmadi, Goodarz

2011-11-01

The quality of indoor air environment is very important for improving the health of occupants and reducing personal exposure to hazardous pollutants. An effective way of controlling air quality is by eliminating the airborne bacteria and viruses or by reducing their emissions. Ultraviolet Germicidal Irradiation (UVGI) lamps can effectively reduce these bio-contaminants in an indoor environment, but the efficiency of these systems depends on airflow in and around the device. UVGI lamps would not be as effective in stagnant environments as they would be when the moving air brings the bio-contaminant in their irradiation region. Introducing a fan into the UVGI system would augment the efficiency of the system's kill rate. Airflows in ventilated spaces are quite complex due to the vast range of length and velocity scales. The purpose of this research is to study these complex airflows using CFD techniques and validate computational model with airflow measurements around the device using Particle Image Velocimetry measurements. The experimental results including mean velocities, length scales and RMS values of fluctuating velocities are used in the CFD validation. Comparison of these data at different locations around the device with the CFD model predictions are performed and good agreement was observed.

Fuel composition effect on cathode airflow control in fuel cell gas turbine hybrid systems

NASA Astrophysics Data System (ADS)

Zhou, Nana; Zaccaria, Valentina; Tucker, David

2018-04-01

Cathode airflow regulation is considered an effective means for thermal management in solid oxide fuel cell gas turbine (SOFC-GT) hybrid system. However, performance and controllability are observed to vary significantly with different fuel compositions. Because a complete system characterization with any possible fuel composition is not feasible, the need arises for robust controllers. The sufficiency of robust control is dictated by the effective change of operating state given the new composition used. It is possible that controller response could become unstable without a change in the gains from one state to the other. In this paper, cathode airflow transients are analyzed in a SOFC-GT system using syngas as fuel composition, comparing with previous work which used humidified hydrogen. Transfer functions are developed to map the relationship between the airflow bypass and several key variables. The impact of fuel composition on system control is quantified by evaluating the difference between gains and poles in transfer functions. Significant variations in the gains and the poles, more than 20% in most cases, are found in turbine rotational speed and cathode airflow. The results of this work provide a guideline for the development of future control strategies to face fuel composition changes.

Interfacial distribution of mucus under forced expiration in a double bifurcation model

NASA Astrophysics Data System (ADS)

Rajendran, Rahul; Banerjee, Arindam

2017-11-01

Mucus is removed from the lung airways by the rhythmic beating of cilia and the mucus interaction with the turbulent core airflow generated during a cough or forced expiration. The quantity and quality of mucus are adversely altered, impairing mucociliary clearance under chronic pulmonary conditions. Existing studies on airflow induced mucus clearance have established a functional relationship between the airflow rate, mucus properties, flow bias, breathing frequency and clearance; however, the impact of airway branching, gravity, and characterization of primary and secondary flows have not been studied. The focus of the current investigation is the detailed understanding of air-mucus two-phase flow mechanism under steady expiratory airflow in a double bifurcation model. The effect of different airflow rates and mucus viscosities on the flow morphology, mucus layer thickness, mucus clearance and pressure drop across the model will be discussed. The impact of in-plane and out-of-plane configurations of the bifurcation model on the primary and secondary flow structures as well as the mucus distribution will be addressed. In addition, a detailed comparison of the flow structures in the mucus-lined airways, and its corresponding dry wall (no mucus lining) case will be presented.

Laser irradiation effects on thin aluminum plates subjected to surface flow

NASA Astrophysics Data System (ADS)

Jiang, Houman; Zhao, Guomin; Chen, Minsun; Peng, Xin

2016-10-01

The irradiation effects of LD laser on thin aluminum alloy plates are studied in experiments characterized by relatively large laser spot and the presence of 0.3Ma surface airflow. A high speed profilometer is used to record the profile change along a vertical line in the rear surface of the target, and the history of the displacement along the direction of thickness of the central point at the rear surface is obtained. The results are compared with those without airflow and those by C. D. Boley. We think that it is the temperature rise difference along the direction of thickness instead of the pressure difference caused by the airflow that makes the thin target bulge into the incoming beam, no matter whether the airflow is blown or not, and that only when the thin aluminum target is heated thus softened enough by the laser irradiation, can the aerodynamic force by the surface airflow cause non-ignorable localized plastic deformation and result a burn-through without melting in the target. However, though the target isn't softened enough in terms of the pressure difference, it might have experienced notable deformation as it is heated from room temperature to several hundred degree centigrade.

Thermal properties of highly structured composite and aluminium sheets in an aerodynamic tunnel

NASA Astrophysics Data System (ADS)

Kulhavy, Petr; Egert, Josef

This article deals with the thermodynamic behaviour of heat shields - structured metal and composite plates. Experiments have been carried out in a wind tunnel with an additional heating, which simulates the heat source from engine or exhaust pipe and simultaneously the airflow generated during a car movement. The tested sheets with hexagonal structure were a standard commercial made of aluminium and a second manufactured by replication (lamination, diffusion) from glass fabric. The airflow in a parallel way along the sheets was analysed experimentally in order to determine the heat transfer efficiency between surfaces of sheets and surrounding airflow. The temperature on the sheets was chosen to observe the effects of different sheets material, various heat power and airflow velocity. During the experiment a thermal input below the sheets and airflow velocity through the tunnel have been changed. The thermal field distribution on the metal sheet is different than in case of composite sheet. For the composite material the thermal field distribution was more homogeneous. This article describe briefly also methods of obtaining real composite geometry based on scanned data and their reconstruction for using in some future numerical models.

Microfabricated airflow nozzle for microencapsulation of living cells into 150 micrometer microcapsules.

PubMed

Sugiura, Shinji; Oda, Tatsuya; Aoyagi, Yasuyuki; Matsuo, Ryota; Enomoto, Tsuyoshi; Matsumoto, Kunio; Nakamura, Toshikazu; Satake, Mitsuo; Ochiai, Atsushi; Ohkohchi, Nobuhiro; Nakajima, Mitsutoshi

2007-02-01

Microencapsulation of genetically engineered cells has attracted much attention as an alternative nonviral strategy to gene therapy. Though smaller microcapsules (i.e. less than 300 microm) theoretically have various advantages, technical limitations made it difficult to prove this notion. We have developed a novel microfabricated device, namely a micro-airflow-nozzle (MAN), to produce 100 to 300 microm alginate microcapsules with a narrow size distribution. The MAN is composed of a nozzle with a 60 microm internal diameter for an alginate solution channel and airflow channels next to the nozzle. An alginate solution extruded through the nozzle was sheared by the airflow. The resulting alginate droplets fell directly into a CaCl2 solution, and calcium alginate beads were formed. The device enabled us to successfully encapsulate living cells into 150 microm microcapsules, as well as control microcapsule size by simply changing the airflow rate. The encapsulated cells had a higher growth rate and greater secretion activity of marker protein in 150 microm microcapsules compared to larger microcapsules prepared by conventional methods because of their high diffusion efficiency and effective scaffold surface area. The advantages of smaller microcapsules offer new prospects for the advancement of microencapsulation technology.

Implications of Airflow Dynamics and Soft-Tissue Reconstructions for the Heat Exchange Potential of Dinosaur Nasal Passages

NASA Astrophysics Data System (ADS)

Bourke, Jason Michael

This study seeks to restore the internal anatomy within the nasal passages of dinosaurs via the use of comparative anatomical methods along with computational fluid dynamic simulations. Nasal airway descriptions and airflow simulations are described for extant birds, crocodylians, and lizards. These descriptions served as a baseline for airflow within the nasal passages of diapsids. The presence of shared airflow and soft-tissue properties found in the nasal passages of extant diapsids, were used to restore soft tissues within the airways of dinosaurs under the assumption that biologically unfeasible airflow patterns (e.g., lack of air movement in olfactory recess) can serve as signals for missing soft tissues. This methodology was tested on several dinosaur taxa. Restored airways in some taxa revealed the potential presence and likely shape of nasal turbinates. Heat transfer efficiency was tested in two dinosaur species with elaborated nasal passages. Results of that analysis revealed that dinosaur noses were efficient heat exchangers that likely played an integral role in maintaining cephalic thermoregulation. Brain cooling via nasal expansion appears to have been necessary for dinosaurs to have achieved their immense body sizes without overheating their brains.

Airflow elicits a spider's jump towards airborne prey. I. Airflow around a flying blowfly

PubMed Central

Klopsch, Christian; Kuhlmann, Hendrik C.; Barth, Friedrich G.

2012-01-01

The hunting spider Cupiennius salei uses airflow generated by flying insects for the guidance of its prey-capture jump. We investigated the velocity field of the airflow generated by a freely flying blowfly close to the flow sensors on the spider's legs. It shows three characteristic phases (I–III). (I) When approaching, the blowfly induces an airflow signal near the spider with only little fluctuation (0.013 ± 0.006 m s−1) and a strength that increases nearly exponentially with time (maximum: 0.164 ± 0.051 m s−1 s.d.). The spider detects this flow while the fly is still 38.4 ± 5.6 mm away. The fluctuation of the airflow above the sensors increases linearly up to 0.037 m s−1 with the fly's altitude. Differences in the time of arrival and intensity of the fly signal at different legs probably inform the spider about the direction to the prey. (II) Phase II abruptly follows phase I with a much higher degree of fluctuation (fluctuation amplitudes: 0.114 ± 0.050 m s−1). It starts when the fly is directly above the sensor and corresponds to the time-dependent flow in the wake below and behind the fly. Its onset indicates to the spider that its prey is now within reach and triggers its jump. The spider derives information on the fly's position from the airflow characteristics, enabling it to properly time its jump. The horizontal velocity of the approaching fly is reflected by the time of arrival differences (ranging from 0.038 to 0.108 s) of the flow at different legs and the exponential velocity growth rate (16–79 s−1) during phase I. (III) The air flow velocity decays again after the fly has passed the spider. PMID:22572032

New CFD tools to evaluate nasal airflow.

PubMed

Burgos, M A; Sanmiguel-Rojas, E; Del Pino, C; Sevilla-García, M A; Esteban-Ortega, F

2017-08-01

Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. As currently CFD is not a usual tool for rhinologists, a group of engineers in collaboration with experts in Rhinology have developed a very intuitive CFD software. The program MECOMLAND ® only required snapshots from the patient's cross-sectional (tomographic) images, being the output those results originated by CFD, such as airflow distributions, velocity profiles, pressure, temperature, or wall shear stress. This is useful complementary information to cover diagnosis, prognosis, or follow-up of nasal pathologies based on quantitative magnitudes linked to airflow. In addition, the user-friendly environment NOSELAND ® helps the medical assessment significantly in the post-processing phase with dynamic reports using a 3D endoscopic view. Specialists in Rhinology have been asked for a more intuitive, simple, powerful CFD software to offer more quality and precision in their work to evaluate the nasal airflow. We present MECOMLAND ® and NOSELAND ® which have all the expected characteristics to fulfil this demand and offer a proper assessment with the maximum of quality plus safety for the patient. These programs represent a non-invasive, low-cost (as the CT scan is already performed in every patient) alternative for the functional study of the difficult rhinologic case. To validate the software, we studied two groups of patients from the Ear Nose Throat clinic, a first group with normal noses and a second group presenting septal deviations. Wall shear stresses are lower in the cases of normal noses in comparison with those for septal deviation. Besides, velocity field distributions, pressure drop between nasopharynx and the ambient, and flow rates in each nostril were different among the nasal cavities in the two groups. These software modules open up a promising future to simulate the nasal airflow behaviour in virtual surgery intervention scenarios under different pressure or temperature conditions to understand the effects on nasal airflow.

Improved Cathode Structure for a Direct Methanol Fuel Cell

NASA Technical Reports Server (NTRS)

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

An improved cathode structure on a membrane/electrode assembly has been developed for a direct methanol fuel cell, in a continuing effort to realize practical power systems containing such fuel cells. This cathode structure is intended particularly to afford better cell performance at a low airflow rate. A membrane/electrode assembly of the type for which the improved cathode structure was developed (see Figure 1) is fabricated in a process that includes brush painting and spray coating of catalyst layers onto a polymer-electrolyte membrane and onto gas-diffusion backings that also act as current collectors. The aforementioned layers are then dried and hot-pressed together. When completed, the membrane/electrode assembly contains (1) an anode containing a fine metal black of Pt/Ru alloy, (2) a membrane made of Nafion 117 or equivalent (a perfluorosulfonic acid-based hydrophilic, proton-conducting ion-exchange polymer), (3) a cathode structure (in the present case, the improved cathode structure described below), and (4) the electrically conductive gas-diffusion backing layers, which are made of Toray 060(TradeMark)(or equivalent) carbon paper containing between 5 and 6 weight percent of poly(tetrafluoroethylene). The need for an improved cathode structure arises for the following reasons: In the design and operation of a fuel-cell power system, the airflow rate is a critical parameter that determines the overall efficiency, cell voltage, and power density. It is desirable to operate at a low airflow rate in order to obtain thermal and water balance and to minimize the size and mass of the system. The performances of membrane/electrode assemblies of prior design are limited at low airflow rates. Methanol crossover increases the required airflow rate. Hence, one way to reduce the required airflow rate is to reduce the effect of methanol crossover. Improvement of the cathode structure - in particular, addition of hydrophobic particles to the cathode - has been demonstrated to mitigate the effects of crossover and decrease the airflow required.

The use of combined thermal/pressure polyvinylidene fluoride film airflow sensor in polysomnography.

PubMed

Kryger, Meir; Eiken, Todd; Qin, Li

2013-12-01

The technologies recommended by the American Academy of Sleep Medicine (AASM) to monitor airflow in polysomnography (PSG) include the simultaneous monitoring of two physical variables: air temperature (for thermal airflow) and air pressure (for nasal pressure). To comply with airflow monitoring standards in the sleep lab setting thus often requires the patient to wear two sensors under the nose during testing. We hypothesized that a single combined thermal/pressure sensor using polyvinylidene fluoride (PVDF) film responsive to both airflow temperature and pressure would be effective in documenting abnormal breathing events during sleep. Sixty patients undergoing routine PSG testing to rule out obstructive sleep apnea at two different sleep laboratories were asked to wear a third PVDF airflow sensor in addition to the traditional thermal sensor and pressure sensor. Apnea and hypopnea events were scored by the sleep lab technologists using the AASM guidelines (CMS option) using the thermal sensor for apnea and the pressure sensor for hypopnea (scorer 1). The digital PSG data were also forwarded to an outside registered polysomnographic technologist for scoring of respiratory events detected in the PVDF airflow channels (scorer 2). The Pearson correlation coefficient, r, between apnea and hypopnea indices obtained using the AASM sensors and the combined PVDF sensor was almost unity for the four calculated indices: apnea-hypopnea index (0.990), obstructive apnea index (0.992), hypopnea index (0.958), and central apnea index (1.0). The slope of the four relationships was virtually unity and the coefficient of determination (r (2)) was also close to 1. The results of intraclass correlation coefficients (>0.95) and Bland-Altman plots also provide excellent agreement between the combined PVDF sensor and the AASM sensors. The indices used to calculate apnea severity obtained with the combined PVDF thermal and pressure sensor were equivalent to those obtained using AASM-recommended sensors.

Upper Airway Collapsibility During REM Sleep in Children with the Obstructive Sleep Apnea Syndrome

PubMed Central

Huang, Jingtao; Karamessinis, Laurie R.; Pepe, Michelle E.; Glinka, Stephen M.; Samuel, John M.; Gallagher, Paul R.; Marcus, Carole L.

2009-01-01

Study Objectives: In children, most obstructive events occur during rapid eye movement (REM) sleep. We hypothesized that children with the obstructive sleep apnea syndrome (OSAS), in contrast to age-matched control subjects, would not maintain airflow in the face of an upper airway inspiratory pressure drop during REM sleep. Design: During slow wave sleep (SWS) and REM sleep, we measured airflow, inspiratory time, inspiratory time/total respiratory cycle time, respiratory rate, tidal volume, and minute ventilation at a holding pressure at which flow limitation occurred and at 5 cm H2O below the holding pressure in children with OSAS and in control subjects. Setting: Sleep laboratory. Participants: Fourteen children with OSAS and 23 normal control subjects. Results: In both sleep states, control subjects were able to maintain airflow, whereas subjects with OSAS preserved airflow in SWS but had a significant decrease in airflow during REM sleep (change in airflow of 18.58 ± 12.41 mL/s for control subjects vs −44.33 ± 14.09 mL/s for children with OSAS, P = 0.002). Although tidal volume decreased, patients with OSAS were able to maintain minute ventilation by increasing the respiratory rate and also had an increase in inspiratory time and inspiratory time per total respiratory cycle time Conclusion: Children with OSAS do not maintain airflow in the face of upper-airway inspiratory-pressure drops during REM sleep, indicating a more collapsible upper airway, compared with that of control subjects during REM sleep. However, compensatory mechanisms exist to maintain minute ventilation. Local reflexes, central control mechanisms, or both reflexes and control mechanisms need to be further explored to better understand the pathophysiology of this abnormality and the compensation mechanism. Citation: Huang J; Karamessinis LR; Pepe ME; Glinka SM; Samuel JM; Gallagher PR; Marcus CL. Upper airway collapsibility during REM sleep in children with the obstructive sleep apnea syndrome. SLEEP 2009;32(9):1173-1181. PMID:19750922

Risk factors associated with persistent airflow limitation in severe or difficult-to-treat asthma: insights from the TENOR study.

PubMed

Lee, June H; Haselkorn, Tmirah; Borish, Larry; Rasouliyan, Lawrence; Chipps, Bradley E; Wenzel, Sally E

2007-12-01

The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens study is among the largest to assess persistent airflow limitation and the first to evaluate a wide range of potential risk factors in high-risk patients with severe or difficult-to-treat asthma. A better understanding is needed regarding factors associated with persistent airway obstruction; this study was performed to determine demographic and clinical characteristics associated with persistent airflow limitation. Data from adult patients (>or= 18 years old) with severe or difficult-to-treat asthma were evaluated. Patients with COPD, obesity with a restrictive respiratory pattern, or a >or= 30 pack-year history of smoking were excluded. Patients with persistent airflow limitation (postbronchodilator FEV1/FVC ratio

MICROPROCESSOR CONTROL OF ROTOGRAVURE AIRFLOWS

EPA Science Inventory

The report discusses the technical and economic viability of using micro-processor-based control technology to collect volatile organic compound (VOC) emissions from a paper coating operation. The microprocessor-based control system monitors and controls both the airflow rate and...

A smart, intermittent driven particle sensor with an airflow change trigger using a lead zirconate titanate (PZT) cantilever

NASA Astrophysics Data System (ADS)

Takahashi, Hidetoshi; Tomimatsu, Yutaka; Kobayashi, Takeshi; Isozaki, Akihiro; Itoh, Toshihiro; Maeda, Ryutaro; Matsumoto, Kiyoshi; Shimoyama, Isao

2014-02-01

This paper reports on a smart, intermittent driven particle sensor with an airflow trigger. A lead zirconate titanate cantilever functions as the trigger, which detects an airflow change without requiring a power supply to drive the sensing element. Because an airflow change indicates that the particle concentration has changed, the trigger switches the optical particle counter from sleep mode to active mode only when the particle concentration surrounding the sensor changes. The sensor power consumption in sleep mode is 100 times less than that in the active mode. Thus, this intermittent driven method significantly reduces the total power consumption of the particle sensor. In this paper, we fabricate a prototype of the particle sensor and demonstrate that the optical particle counter can be switched on by the fabricated trigger and thus that the particle concentration can be measured.

Determination of minimum suction level necessary for field dental units.

PubMed

Charlton, David G

2010-04-01

A significant problem with most field dental units is that their suction is too weak to effectively remove debris from the mouth. The purpose of this study was to determine the minimum clinically acceptable suction level for routine dentistry. A vacuum pump was connected to a high-volume dental evacuation line in a simulated clinical setting and different suction airflow rates were evaluated by nine evaluator dentists for their capability to effectively remove amalgam debris and water. Airflow levels were rated as "clinically acceptable" or "clinically unacceptable" by each evaluator. Data were analyzed using a chi2 test for trend. Analysis indicated a significant linear trend between airflow and ratings (p < 0.0001). The first airflow level considered by all evaluators as producing clinically acceptable suction was 4.5 standard cubic feet per minute (0.127 standard cubic meters per minute). This value should be the minimum level required for all military field dental units.

Difference in airflow obstruction between Hispanic and non-Hispanic White female smokers.

PubMed

Sood, Akshay; Stidley, Christine A; Picchi, Maria A; Celedón, Juan C; Gilliland, Frank; Crowell, Richard E; Belinsky, Steven A; Tesfaigzi, Yohannes

2008-10-01

Smoking-related respiratory diseases are a major cause of morbidity and mortality. However, the relationship between smoking and respiratory disease has not been well-studied among ethnic minorities in general and among women in particular. The objective of this cross-sectional study was to evaluate the risk of airflow obstruction and to assess lung function among Hispanic and non-Hispanic White (NHW) female smokers in a New Mexico cohort. Participants completed a questionnaire detailing smoking history and underwent spirometry testing. Outcomes studied included airflow obstruction, selected lung function parameters, and chronic mucus hyper-secretion. Chi square, logistic, and linear regression techniques were utilized. Of the 1,433 eligible women participants, 248 (17.3%) were Hispanic; and 319 had airflow obstruction (22.3%). Hispanic smokers were more likely to be current smokers, and report lower pack-years of smoking, compared to NHW smokers (p < 0.05 for all analyses). Further, Hispanic smokers were at a reduced risk of airflow obstruction compared to NHW smokers, with an O.R. of 0.51, 95% C.I. 0.34, 0.78 (p = 0.002) after adjustment for age, BMI, pack-years and duration of smoking, and current smoking status. Following adjustment for covariates, Hispanic smokers also had a higher mean absolute and percent predicted post-bronchodilator FEV(1)/FVC ratio, as well as higher mean percent predicted FEV(1) (p < 0.05 for all analyses). Hispanic female smokers in this New Mexico-based cohort had lower risk of airflow obstruction and better lung function than NHW female smokers. Further, smoking history did not completely explain these associations.

Clinically remitted childhood asthma is associated with airflow obstruction in middle-aged adults.

PubMed

Omori, Keitaro; Iwamoto, Hiroshi; Yamane, Takashi; Nakashima, Taku; Haruta, Yoshinori; Hattori, Noboru; Yokoyama, Akihito; Kohno, Nobuoki

2017-01-01

While adult asthma has been shown to be a risk factor for COPD, the effect of remitted childhood asthma on adult lung function has not been clarified. The aim of this study was to examine whether remitted childhood asthma is a risk factor for airflow obstruction in a middle-aged general population. A total of 9896 participants (range: 35-60 years) from five healthcare centres were included in the study. The participants were classified into four categories based on the presence or absence of physician-diagnosed childhood/adulthood asthma and asthma symptoms as follows: healthy controls (n = 9154), remitted childhood asthma (n = 287), adulthood-onset asthma (n = 354) and childhood-adulthood asthma (n = 101). The prevalence of respiratory symptoms was similar in both the participants with remitted childhood asthma and healthy controls. The prevalence of airflow obstruction (forced expiratory volume in 1 s (FEV 1 )/forced vital capacity (FVC) < 0.7) was significantly higher in the participants with remitted childhood asthma, those with adult-onset asthma and those with childhood-adulthood asthma (5.2%, 14.4% and 16.8%, respectively) compared with healthy controls (2.2%). Multivariate logistic regression showed that remitted childhood asthma was independently associated with airflow obstruction. Among the participants with remitted childhood asthma, ever-smokers had significantly lower FEV 1 /FVC than never-smokers. Clinically remitted childhood asthma is associated with airflow obstruction in middle-aged adults. Smoking and remitted childhood asthma may be additive factors for the development of airflow obstruction. © 2016 Asian Pacific Society of Respirology.

Air quality and passenger comfort in an air-conditioned bus micro-environment.

PubMed

Zhu, Xiaoxuan; Lei, Li; Wang, Xingshen; Zhang, Yinghui

2018-04-12

In this study, passenger comfort and the air pollution status of the micro-environmental conditions in an air-conditioned bus were investigated through questionnaires, field measurements, and a numerical simulation. As a subjective analysis, passengers' perceptions of indoor environmental quality and comfort levels were determined from questionnaires. As an objective analysis, a numerical simulation was conducted using a discrete phase model to determine the diffusion and distribution of pollutants, including particulate matter with a diameter < 10 μm (PM 10 ), which were verified by experimental results. The results revealed poor air quality and dissatisfactory thermal comfort conditions in Jinan's air-conditioned bus system. To solve these problems, three scenarios (schemes A, B, C) were designed to alter the ventilation parameters. According to the results of an improved simulation of these scenarios, reducing or adding air outputs would shorten the time taken to reach steady-state conditions and weaken the airflow or lower the temperature in the cabin. The airflow pathway was closely related to the layout of the air conditioning. Scheme B lowered the temperature by 0.4 K and reduced the airflow by 0.01 m/s, while scheme C reduced the volume concentration of PM 10 to 150 μg/m 3 . Changing the air supply angle could further improve the airflow and reduce the concentration of PM 10 . With regard to the perception of airflow and thermal comfort, the scheme with an airflow provided by a 60° nozzle was considered better, and the concentration of PM 10 was reduced to 130 μg/m 3 .

Measured Performance of a Varied Airflow Small-Diameter Duct System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poerschke, Andrew

2017-03-01

This study tests the performance of a variable airflow small-diameter duct heating, ventilation, and air conditioning (HVAC) system in a new construction unoccupied low-load test house in Pittsburgh, Pennsylvania. The duct system was installed entirely in conditioned space and was operated from the winter through summer seasons. Measurements were collected on the in-room temperatures and energy consumed by the air handler and heat pump unit. Operation modes with three different volumes of airflow were compared to determine the ideal airflow scenario that maximizes room-to-room thermal uniformity while minimizing fan energy consumption. Black felt infrared imagery was used as a measuremore » of diffuser throw and in-room air mixing. Measured results indicate the small-diameter, high velocity airflow system can provide comfort under some conditions. Solar heat gains resulted in southern rooms drifting beyond acceptable temperature limits. Insufficient airflow to some bedrooms also resulted in periods of potential discomfort. Homebuilders or HVAC contractors can use these results to assess whether this space conditioning strategy is an attractive alternative to a traditional duct system. The team performed a cost analysis of two duct system configurations: (1) a conventional diameter and velocity duct system, and (2) the small-diameter duct system. This work applies to both new and retrofit homes that have achieved a low heating and cooling density either by energy conservation or by operation in a mild climate with few heating or cooling degree days. Guidance is provided on cost trade-offs between the conventional duct system and the small-diameter duct system.« less

Measured Performance of a Varied Airflow Small-Diameter Duct System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poerschke, Andrew

This study tests the performance of a variable airflow small-diameter duct heating, ventilation, and air conditioning (HVAC) system in a new construction unoccupied low-load test house in Pittsburgh, Pennsylvania. The duct system was installed entirely in conditioned space and was operated from the winter through summer seasons. Measurements were collected on the in-room temperatures and energy consumed by the air handler and heat pump unit. Operation modes with three different volumes of airflow were compared to determine the ideal airflow scenario that maximizes room-to-room thermal uniformity while minimizing fan energy consumption. Black felt infrared imagery was used as a measuremore » of diffuser throw and in-room air mixing. Measured results indicate the small-diameter, high velocity airflow system can provide comfort under some conditions. Solar heat gains resulted in southern rooms drifting beyond acceptable temperature limits. Insufficient airflow to some bedrooms also resulted in periods of potential discomfort. Homebuilders or HVAC contractors can use these results to assess whether this space conditioning strategy is an attractive alternative to a traditional duct system. The team performed a cost analysis of two duct system configurations: (1) a conventional diameter and velocity duct system, and (2) the small-diameter duct system. This work applies to both new and retrofit homes that have achieved a low heating and cooling density either by energy conservation or by operation in a mild climate with few heating or cooling degree days. Guidance is provided on cost trade-offs between the conventional duct system and the small-diameter duct system.« less

Implications of Natural Occlusion of Ventilated Racks on Ammonia and Sanitation Practices

PubMed Central

Creamer, Michelle A; Petty, Joann; Martin, Tara; Bergdall, Valerie; Hickman-Davis, Judy M

2014-01-01

Examination of ventilated rat racks prior to semiannual sanitation revealed silicone nozzles and ventilation ports that were partially or completely occluded with granular debris. We subsequently sought to document performance standards for rack sanitation and investigate the effect of ventilation port occlusion on rack function and animal husbandry practices. We hypothesized that individually ventilated cages with occluded airflow would require more frequent cage changes, comparable to those for static cages (that is, every 3 to 4 d). Sprague–Dawley rats were housed under one of 4 conditions: no airflow occlusion, occluded air-supply inlet, occluded air-exhaust outlet, and occlusion of both inlet and outlet. Cages were changed when daily ammonia concentration exceeded 20 ppm or after 14 d had elapsed. Most cages with unoccluded or partial airflow occlusion remained below the 20 ppm limit until day 12 or 13. Cages with occlusion of both inlet and outlet exceeded 20 ppm ammonia by as early as day 5. Airflow was significantly lower in cages with occlusion of both inlet and outlet airflow. Weekly inspection revealed that occlusion of ventilation ports was detectable by 3 mo after semiannual sanitation. This study demonstrates that silicone nozzles should be removed prior to rack sanitation to improve the effectiveness of cleaning ventilation ports and nozzles. While the rack is in use, silicone nozzles and ventilation ports should be inspected regularly to identify occlusion that is likely to diminish environmental quality in the cage. Intracage ammonia levels are significantly higher when both inlet and outlet airflow are occluded. PMID:24602544

Implications of natural occlusion of ventilated racks on ammonia and sanitation practices.

PubMed

Creamer, Michelle A; Petty, Joann; Martin, Tara; Bergdall, Valerie; Hickman-Davis, Judy M

2014-03-01

Examination of ventilated rat racks prior to semiannual sanitation revealed silicone nozzles and ventilation ports that were partially or completely occluded with granular debris. We subsequently sought to document performance standards for rack sanitation and investigate the effect of ventilation port occlusion on rack function and animal husbandry practices. We hypothesized that individually ventilated cages with occluded airflow would require more frequent cage changes, comparable to those for static cages (that is, every 3 to 4 d). Sprague-Dawley rats were housed under one of 4 conditions: no airflow occlusion, occluded air-supply inlet, occluded air-exhaust outlet, and occlusion of both inlet and outlet. Cages were changed when daily ammonia concentration exceeded 20 ppm or after 14 d had elapsed. Most cages with unoccluded or partial airflow occlusion remained below the 20 ppm limit until day 12 or 13. Cages with occlusion of both inlet and outlet exceeded 20 ppm ammonia by as early as day 5. Airflow was significantly lower in cages with occlusion of both inlet and outlet airflow. Weekly inspection revealed that occlusion of ventilation ports was detectable by 3 mo after semiannual sanitation. This study demonstrates that silicone nozzles should be removed prior to rack sanitation to improve the effectiveness of cleaning ventilation ports and nozzles. While the rack is in use, silicone nozzles and ventilation ports should be inspected regularly to identify occlusion that is likely to diminish environmental quality in the cage. Intracage ammonia levels are significantly higher when both inlet and outlet airflow are occluded.

A computational study of the respiratory airflow characteristics in normal and obstructed human airways.

PubMed

Sul, Bora; Wallqvist, Anders; Morris, Michael J; Reifman, Jaques; Rakesh, Vineet

2014-09-01

Obstructive lung diseases in the lower airways are a leading health concern worldwide. To improve our understanding of the pathophysiology of lower airways, we studied airflow characteristics in the lung between the 8th and the 14th generations using a three-dimensional computational fluid dynamics model, where we compared normal and obstructed airways for a range of breathing conditions. We employed a novel technique based on computing the Pearson׳s correlation coefficient to quantitatively characterize the differences in airflow patterns between the normal and obstructed airways. We found that the airflow patterns demonstrated clear differences between normal and diseased conditions for high expiratory flow rates (>2300ml/s), but not for inspiratory flow rates. Moreover, airflow patterns subjected to filtering demonstrated higher sensitivity than airway resistance for differentiating normal and diseased conditions. Further, we showed that wall shear stresses were not only dependent on breathing rates, but also on the distribution of the obstructed sites in the lung: for the same degree of obstruction and breathing rate, we observed as much as two-fold differences in shear stresses. In contrast to previous studies that suggest increased wall shear stress due to obstructions as a possible damage mechanism for small airways, our model demonstrated that for flow rates corresponding to heavy activities, the wall shear stress in both normal and obstructed airways was <0.3Pa, which is within the physiological limit needed to promote respiratory defense mechanisms. In summary, our model enables the study of airflow characteristics that may be impractical to assess experimentally. Published by Elsevier Ltd.

A 305-year continuous monthly rainfall series for the island of Ireland (1711-2016)

NASA Astrophysics Data System (ADS)

Murphy, Conor; Broderick, Ciaran; Burt, Timothy P.; Curley, Mary; Duffy, Catriona; Hall, Julia; Harrigan, Shaun; Matthews, Tom K. R.; Macdonald, Neil; McCarthy, Gerard; McCarthy, Mark P.; Mullan, Donal; Noone, Simon; Osborn, Timothy J.; Ryan, Ciara; Sweeney, John; Thorne, Peter W.; Walsh, Seamus; Wilby, Robert L.

2018-03-01

A continuous 305-year (1711-2016) monthly rainfall series (IoI_1711) is created for the Island of Ireland. The post 1850 series draws on an existing quality assured rainfall network for Ireland, while pre-1850 values come from instrumental and documentary series compiled, but not published by the UK Met Office. The series is evaluated by comparison with independent long-term observations and reconstructions of precipitation, temperature and circulation indices from across the British-Irish Isles. Strong decadal consistency of IoI_1711 with other long-term observations is evident throughout the annual, boreal spring and autumn series. Annually, the most recent decade (2006-2015) is found to be the wettest in over 300 years. The winter series is probably too dry between the 1740s and 1780s, but strong consistency with other long-term observations strengthens confidence from 1790 onwards. The IoI_1711 series has remarkably wet winters during the 1730s, concurrent with a period of strong westerly airflow, glacial advance throughout Scandinavia and near unprecedented warmth in the Central England Temperature record - all consistent with a strongly positive phase of the North Atlantic Oscillation. Unusually wet summers occurred in the 1750s, consistent with proxy (tree-ring) reconstructions of summer precipitation in the region. Our analysis shows that inter-decadal variability of precipitation is much larger than previously thought, while relationships with key modes of climate variability are time-variant. The IoI_1711 series reveals statistically significant multi-centennial trends in winter (increasing) and summer (decreasing) seasonal precipitation. However, given uncertainties in the early winter record, the former finding should be regarded as tentative. The derived record, one of the longest continuous series in Europe, offers valuable insights for understanding multi-decadal and centennial rainfall variability in Ireland, and provides a firm basis for benchmarking other long-term records and reconstructions of past climate. Correlation of Irish rainfall with other parts of Europe increases the utility of the series for understanding historical climate in further regions.

Airflow and nanoparticle deposition in a 16-generation tracheobronchial airway model

EPA Science Inventory

In order to achieve both manageable simulation and local accuracy of airflow and nanoparticle deposition in a representative human tracheobronchial (TB) region, the complex airway network was decomposed into adjustable triple-bifurcation units, spreading axially and laterally. Gi...

A dynamic ventilation model for gravity sewer networks.

PubMed

Wang, Y C; Nobi, N; Nguyen, T; Vorreiter, L

2012-01-01

To implement any effective odour and corrosion control technology in the sewer network, it is imperative that the airflow through gravity sewer airspaces be quantified. This paper presents a full dynamic airflow model for gravity sewer systems. The model, which is developed using the finite element method, is a compressible air transport model. The model has been applied to the North Head Sewerage Ocean Outfall System (NSOOS) and calibrated using the air pressure and airflow data collected during October 2008. Although the calibration is focused on forced ventilation, the model can be applied to natural ventilation as well.

Velopharyngeal port status during classical singing.

PubMed

Tanner, Kristine; Roy, Nelson; Merrill, Ray M; Power, David

2005-12-01

This investigation was undertaken to examine the status of the velopharyngeal (VP) port during classical singing. Using aeromechanical instrumentation, nasal airflow (mL/s), oral pressure (cm H2O), and VP orifice area estimates (cm2) were studied in 10 classically trained sopranos during singing and speaking. Each participant sang and spoke 3 nonsense words-/hampa/, /himpi/, and /humpu/-at 3 loudness levels (loud vs. comfortable vs. soft) and 3 pitches (high vs. comfortable vs. low), using a within-subject experimental design including all possible combinations. In general, nasal airflow, oral pressure, and VP area estimates were significantly greater for singing as compared to speech, and nasal airflow was observed during non-nasal sounds in all participants. Anticipatory nasal airflow was observed in 9 of 10 participants for singing and speaking and was significantly greater during the first vowel in /hampa/ versus /himpi/ and /humpu/. The effect of vowel height on nasal airflow was also significantly influenced by loudness and pitch. The results from this investigation indicate that at least some trained singers experience regular VP opening during classical singing. Vowel height seems to influence this effect. Future research should consider the effects of voice type, gender, experience level, performance ability, and singing style on VP valving in singers.

Numerical simulation of soft palate movement and airflow in human upper airway by fluid-structure interaction method

NASA Astrophysics Data System (ADS)

Sun, Xiuzhen; Yu, Chi; Wang, Yuefang; Liu, Yingxi

2007-08-01

In this paper, the authors present airflow field characteristics of human upper airway and soft palate movement attitude during breathing. On the basis of the data taken from the spiral computerized tomography images of a healthy person and a patient with Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS), three-dimensional models of upper airway cavity and soft palate are reconstructed by the method of surface rendering. Numerical simulation is performed for airflow in the upper airway and displacement of soft palate by fluid-structure interaction analysis. The reconstructed three-dimensional models precisely preserve the original configuration of upper airways and soft palate. The results of the pressure and velocity distributions in the airflow field are quantitatively determined, and the displacement of soft palate is presented. Pressure gradients of airway are lower for the healthy person and the airflow distribution is quite uniform in the case of free breathing. However, the OSAHS patient remarkably escalates both the pressure and velocity in the upper airway, and causes higher displacement of the soft palate. The present study is useful in revealing pathogenesis and quantitative mutual relationship between configuration and function of the upper airway as well as in diagnosing diseases related to anatomical structure and function of the upper airway.

Late Holocene climate variability from Lake Pupuke maar, Auckland, New Zealand

NASA Astrophysics Data System (ADS)

Striewski, B.; Shulmeister, J.; Augustinus, P. C.; Soderholm, J.

2013-10-01

Spectral analyses of quasi-annual organo-diatomaceous laminae couplets in an Auckland maar lake indicate brief (sub-decadal scale) episodes with strong spectral power and long periods of weak to no spectral power between c. 1700 to c. 550 cal. yr BP. Laminae couplet thickness appears to be a function of changes in wind flow over the basin, with enhanced wind flow deepening the mixing zone and providing additional nutrients for laminae formation. Aeolian dust from Australia amplifies the wind signal. Spectral signals in the high power episodes are focused in <4 years and 6-8 years windows. These are consistent with El Niño-Southern Oscillation (ENSO) periodicity. This climate system is known to play a major role in the modern Auckland climate whereby strongly negative (positive) ENSO are associated with enhanced (diminished) SW airflow over Auckland. ENSO events interact in the modern climate and the spectral results indicate that this is the case when spectral power is strong in the laminae. These results highlight strong but intermittent ENSO activity between 600 and 1400 cal. yr BP.

Investigation of the effects of miniscrew-assisted rapid palatal expansion on airflow in the upper airway of an adult patient with obstructive sleep apnea syndrome using computational fluid-structure interaction analysis

PubMed Central

Hur, Jae-Sik; Kim, Hyoung-Ho; Choi, Jin-Young; Suh, Sang-Ho

2017-01-01

Objective The objective of this study was to investigate the effects of miniscrew-assisted rapid palatal expansion (MARPE) on changes in airflow in the upper airway (UA) of an adult patient with obstructive sleep apnea syndrome (OSAS) using computational fluid-structure interaction analysis. Methods Three-dimensional UA models fabricated from cone beam computed tomography images obtained before (T0) and after (T1) MARPE in an adult patient with OSAS were used for computational fluid dynamics with fluid-structure interaction analysis. Seven and nine cross-sectional planes (interplane distance of 10 mm) in the nasal cavity (NC) and pharynx, respectively, were set along UA. Changes in the cross-sectional area and changes in airflow velocity and pressure, node displacement, and total resistance at maximum inspiration (MI), rest, and maximum expiration (ME) were investigated at each plane after MARPE. Results The cross-sectional areas at most planes in NC and the upper half of the pharynx were significantly increased at T1. Moreover, airflow velocity decreased in the anterior NC at MI and ME and in the nasopharynx and oropharynx at MI. The decrease in velocity was greater in NC than in the pharynx. The airflow pressure in the anterior NC and entire pharynx exhibited a decrease at T1. The amount of node displacement in NC and the pharynx was insignificant at both T0 and T1. Absolute values for the total resistance at MI, rest, and ME were lower at T1 than at T0. Conclusions MARPE improves airflow and decreases resistance in UA; therefore, it may be an effective treatment modality for adult patients with moderate OSAS. PMID:29090123

Response characteristics for thermal and pressure devices commonly used for monitoring nasal and oral airflow during sleep studies.

PubMed

Gehring, J M; Cho, J-G; Wheatley, J R; Amis, T C

2014-03-01

We examined thermocouple and pressure cannulae responses to oral and nasal airflow using a polyester model of a human face, with patent nasal and oral orifices instrumented with a dual thermocouple (F-ONT2A, Grass) or a dual cannula (0588, Braebon) pressure transducer (± 10 cm H2O, Celesco) system. Tidal airflow was generated using a dual compartment facemask with pneumotachographs (Fleisch 2) connected to the model orifices. During nasal breathing: thermocouple amplitude = 0.38 Ln [pneumotachograph amplitude] + 1.31 and pressure cannula amplitude = 0.93 [pneumotachograph amplitude](2.15); during oral breathing: thermocouple amplitude = 0.44 Ln [pneumotachograph amplitude] + 1.07 and pressure cannula amplitude = 0.33 [pneumotachograph amplitude](1.72); (all range ∼ 0.1-∼ 4.0 L s(-1); r(2) > 0.7). For pneumotachograph amplitudes <1 L s(-1) (linear model) change in thermocouple amplitude/unit change in pneumotachograph amplitude was similar for nasal and oral airflow, whereas nasal pressure cannula amplitude/unit change in pneumotachograph amplitude was almost four times that for oral. Increasing oral orifice area from 0.33 cm(2) to 2.15 cm(2) increased oral thermocouple amplitude/unit change in pneumotachograph amplitude by ∼ 58% but decreased pressure cannula amplitude/unit change in pneumotachograph amplitude by 49%. For pneumotachograph amplitudes up to 1 L s(-1), alterations in inspiratory/expiratory ratios or total respiratory time did not affect the sensitivity of either nasal or oral pressure cannulae or the nasal thermocouple, but the oral thermocouple sensitivity was influenced by respiratory cycle time. Different nasal and oral responses influence the ability of these systems to quantitatively assess nasal and oral airflow and oro-nasal airflow partitioning.

Pneumonia risk with inhaled fluticasone furoate and vilanterol in COPD patients with moderate airflow limitation: The SUMMIT trial.

PubMed

Crim, Courtney; Calverley, Peter M A; Anderson, Julie A; Holmes, Andrew P; Kilbride, Sally; Martinez, Fernando J; Brook, Robert D; Newby, David E; Yates, Julie C; Celli, Bartolomé R; Vestbo, Jørgen

2017-10-01

Pneumonia risk with inhaled corticosteroid use in chronic obstructive pulmonary disease (COPD) has not been thoroughly assessed in patients with moderate airflow limitation. To determine the incidence of pneumonia and risk factors in COPD patients with moderate airflow limitation who had, or were at high risk for cardiovascular disease. In the Study to Understand Mortality and MorbidITy in COPD (SUMMIT), 16,590 subjects with moderate airflow limitation (50% ≤ FEV 1  ≤ 70% predicted) and heightened cardiovascular risk were randomized double-blind 1:1:1:1 to inhaled once-daily vilanterol 25 μg (VI), fluticasone furoate 100 μg (FF), vilanterol 25 μg combined with 100 μg fluticasone furoate (FF/VI), or matched placebo. In a pre-specified analysis, we assessed investigator-reported adverse pneumonia events, and independently-adjudicated fatal events. The safety population comprised 16,568 subjects who actually received study medication. There were 1017 pneumonia events reported from 842 subjects. For placebo, FF, VI and FF/VI, reported pneumonia incidence was 5%, 5%, 4% and 6%, respectively. When adjusted for time on treatment, event rates were similar in the placebo, FF and FF/VI containing arms (3.84, 4.24 and 3.95/100 treatment years, respectively) but lower in the VI group (2.77/100 treatment years). Risk factors for pneumonia risk included: greater degree of airflow limitation (i.e. FEV 1 <60% predicted), prior exacerbation history, and BMI <25 kg/m 2 . In contrast to previous studies in patients with severe disease, increased pneumonia risk with inhaled corticosteroid use was not evident in COPD subjects with moderate airflow limitation and heightened cardiovascular risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

Operating theatre ventilation systems and microbial air contamination in total joint replacement surgery: results of the GISIO-ISChIA study.

PubMed

Agodi, A; Auxilia, F; Barchitta, M; Cristina, M L; D'Alessandro, D; Mura, I; Nobile, M; Pasquarella, C

2015-07-01

Recent studies have shown a higher rate of surgical site infections in hip prosthesis implantation using unidirectional airflow ventilation compared with turbulent ventilation. However, these studies did not measure the air microbial quality of operating theatres (OTs), and assumed it to be compliant with the recommended standards for this ventilation technique. To evaluate airborne microbial contamination in OTs during hip and knee replacement surgery, and compare the findings with values recommended for joint replacement surgery. Air samplings were performed in 28 OTs supplied with unidirectional, turbulent and mixed airflow ventilation. Samples were collected using passive sampling to determine the index of microbial air contamination (IMA). Active sampling was also performed in some of the OTs. The average number of people in the OT and the number of door openings during the sampling period were recorded. In total, 1228 elective prosthesis procedures (60.1% hip and 39.9% knee) were included in this study. Of passive samplings performed during surgical activity in unidirectional airflow ventilation OTs (U-OTs) and mixed airflow OTs (M-OTs), 58.9% and 87.6% had IMA values >2, respectively. Of samplings performed during surgical activity in turbulent airflow OTs (T-OTs) and in turbulent airflow OTs with the surgical team wearing Steri-Shield Turbo Helmets (TH-OTs), 8.6% and 60% had IMA values ≤ 2, respectively. Positive correlation was found between IMA values and the number of people in the OT and the number of door openings (P < 0.001). In addition, correlation was found between active and passive sampling (P < 0.001). These findings challenge the belief that unidirectional systems always provide acceptable airborne bacterial counts. Copyright © 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Individuality of breathing during volitional moderate hyperventilation.

PubMed

Besleaga, Tudor; Blum, Michaël; Briot, Raphaël; Vovc, Victor; Moldovanu, Ion; Calabrese, Pascale

2016-01-01

The aim of this study is to investigate the individuality of airflow shapes during volitional hyperventilation. Ventilation was recorded on 18 healthy subjects following two protocols: (1) spontaneous breathing (SP1) followed by a volitional hyperventilation at each subject's spontaneous (HVSP) breathing rate, (2) spontaneous breathing (SP2) followed by hyperventilation at 20/min (HV20). HVSP and HV20 were performed at the same level of hypocapnia: end tidal CO2 (FETCO2) was maintained at 1% below the spontaneous level. At each breath, the tidal volume (VT), the breath (TTOT), the inspiratory (TI) and expiratory durations, the minute ventilation, VT/TI, TI/TTOT and the airflow shape were quantified by harmonic analysis. Under different conditions of breathing, we test if the airflow profiles of the same individual are more similar than airflow profiles between individuals. Minute ventilation was not significantly different between SP1 (6.71 ± 1.64 l·min(-1)) and SP2 (6.57 ± 1.31 l·min(-1)) nor between HVSP (15.88 ± 4.92 l·min(-1)) and HV20 (15.87 ± 4.16 l·min(-1)). Similar results were obtained for FETCO2 between SP1 (5.06 ± 0.54 %) and SP2 (5.00 ± 0.51%), and HVSP (4.07 ± 0.51%) and HV20 (3.88 ± 0.42%). Only TI/TTOT remained unchanged in all four conditions. Airflow shapes were similar when comparing SP1-SP2, HVSP-HV20, and SP1-HVSP but not similar when comparing SP2-HV20. These results suggest the existence of an individuality of airflow shape during volitional hyperventilation. We conclude that volitional ventilation alike automatic breathing follows inherent properties of the ventilatory system. Registered by Pascale Calabrese on ClinicalTrials.gov, # NCT01881945.

An examination of elicitation method on fundamental frequency and repeatability of average airflow measures in children age 4:0-5:11 years.

PubMed

Brehm, Susan Baker; Weinrich, Barbara D; Sprouse, Dana C; May, Shelley K; Hughes, Michael R

2012-11-01

The purpose of this study was to determine the effect of task type on fundamental frequency (F(0)) and the short-term repeatability of average airflow values in preschool/kindergarten-age children. Prospective, experimental. Thirty healthy children (age 4.0-5.11 years) were included in this study. Participants completed three tasks (sustained vowel, counting, and storytelling) used to elicit measurements of F(0). With a 10-minute interval, participants also completed two trials of sustained /a/ at a comfortable pitch and loudness level for the measurement of average airflow rate. F(0) and intensity of the vowel production were recorded for both trials. A repeated measures analysis of variance revealed a significant main effect for task type elicitation on F(0) values (P=0.0003). A significant difference between elicitation tasks for F(0) was observed in the comparison of the counting and storytelling task (P<0.0001). A paired t test revealed no significant difference in average airflow rate across two trials (P=0.872). The change in F(0) and intensity was measured across the trials, and separate analyses of covariance revealed that these changes did not significantly influence average airflow values, (P=0.809) and (P=0.365), respectively. The results of this study demonstrated that F(0) may be influenced by task type in young children. Average airflow values appear to be stable over a short time period. This information is important in determining methods of evaluation and the reliability of instrumental measures in young children with voice disorders. Copyright © 2012 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

Prevalence of asthma with airflow limitation, COPD, and COPD with variable airflow limitation in older subjects in a general Japanese population: the Hisayama Study.

PubMed

Matsumoto, Koichiro; Seki, Nanae; Fukuyama, Satoru; Moriwaki, Atsushi; Kan-o, Keiko; Matsunaga, Yuko; Noda, Naotaka; Yoshida, Makoto; Koto, Hiroshi; Takata, Shohei; Nakanishi, Yoichi; Kiyohara, Yutaka; Inoue, Hiromasa

2015-01-01

Elucidating the prevalence of asthma and chronic obstructive pulmonary disease (COPD) is important for designing a public health strategy. Recent studies have discriminated a phenotype of COPD with variable airflow limitation (COPD-VAL) associated with asthma-COPD overlap syndrome. Its prevalence remains uncertain. The age and occupational distributions in the town of Hisayama and in Japan are nearly identical. Each disease's prevalence was estimated for the town's residents. In 2008, town residents (≥ 40 years) were solicited to participate in a health checkup. Individuals with abnormal spirometry (forced expiratory volume in 1s/forced vital capacity [FEV1/FVC]<70% and/or %FVC<80%) were recommended for further evaluations. Two pulmonologists in a blinded fashion reviewed their medical records, including bronchodilator reversibility. Individuals with airflow limitation were classified as having asthma, COPD, COPD-VAL, or other diseases. The prevalence of each disease was then estimated. A total of 2100 residents (43.4% of residents in the age group) completed spirometry. In 455 residents with abnormal spirometry, 190 residents had further evaluations, and the medical records of 174 residents were reviewed. The prevalence of asthma with airflow limitation, COPD, and COPD-VAL, were 2.0%, 8.4%, and 0.9%, respectively. The prevalence of COPD and COPD-VAL were higher in men and smokers than in women and never-smokers. The prevalence of COPD, but not COPD-VAL or asthma, increased with age. The prevalence of asthma with airflow limitation, COPD, and COPD-VAL were estimated in a population of residents (≥ 40 years) in Hisayama. Copyright © 2014 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Impacts of Realistic Urban Heating, Part I: Spatial Variability of Mean Flow, Turbulent Exchange and Pollutant Dispersion

NASA Astrophysics Data System (ADS)

Nazarian, Negin; Martilli, Alberto; Kleissl, Jan

2018-03-01

As urbanization progresses, more realistic methods are required to analyze the urban microclimate. However, given the complexity and computational cost of numerical models, the effects of realistic representations should be evaluated to identify the level of detail required for an accurate analysis. We consider the realistic representation of surface heating in an idealized three-dimensional urban configuration, and evaluate the spatial variability of flow statistics (mean flow and turbulent fluxes) in urban streets. Large-eddy simulations coupled with an urban energy balance model are employed, and the heating distribution of urban surfaces is parametrized using sets of horizontal and vertical Richardson numbers, characterizing thermal stratification and heating orientation with respect to the wind direction. For all studied conditions, the thermal field is strongly affected by the orientation of heating with respect to the airflow. The modification of airflow by the horizontal heating is also pronounced for strongly unstable conditions. The formation of the canyon vortices is affected by the three-dimensional heating distribution in both spanwise and streamwise street canyons, such that the secondary vortex is seen adjacent to the windward wall. For the dispersion field, however, the overall heating of urban surfaces, and more importantly, the vertical temperature gradient, dominate the distribution of concentration and the removal of pollutants from the building canyon. Accordingly, the spatial variability of concentration is not significantly affected by the detailed heating distribution. The analysis is extended to assess the effects of three-dimensional surface heating on turbulent transfer. Quadrant analysis reveals that the differential heating also affects the dominance of ejection and sweep events and the efficiency of turbulent transfer (exuberance) within the street canyon and at the roof level, while the vertical variation of these parameters is less dependent on the detailed heating of urban facets.

Causes and Consequences of Exceptional North Atlantic Heat Loss in Recent Winters

NASA Astrophysics Data System (ADS)

Josey, Simon; Grist, Jeremy; Duchez, Aurelie; Frajka-Williams, Eleanor; Hirschi, Joel; Marsh, Robert; Sinha, Bablu

2016-04-01

The mid-high latitude North Atlantic loses large amounts of heat to the atmosphere in winter leading to dense water formation. An examination of reanalysis datasets (ERA-Interim, NCEP/NCAR) reveals that heat loss in the recent winters 2013-14 and 2014-15 was exceptionally strong. The causes and consequences of this extraordinary ocean heat loss will be discussed. In 2013-2014, the net air-sea heat flux anomaly averaged over the whole winter exceeded 100 Wm-2 in the eastern subpolar gyre (the most extreme in the period since 1979 spanned by ERA-Interim). The causes of this extreme heat loss will be shown to be severe latent and sensible heat fluxes driven primarily by anomalously strong westerly airflows from North America and northerly airflows originating in the Nordic Seas. The associated sea level pressure anomaly field reflects the dominance of the second mode of atmospheric variability, the East Atlantic Pattern (EAP) over the North Atlantic Oscillation (NAO) in this winter. The extreme winter heat loss had a significant impact on the ocean extending from the sea surface into the deeper layers and a re-emergent cold Sea Surface Temperature (SST) anomaly is evident in November 2014. The following winter 2014-15 experienced further extreme heat loss that served to amplify the strength of the re-emergent SST anomaly. By summer 2015, an unprecedented cold mid-latitude North Atlantic Ocean surface temperature anomaly is evident in observations and has been widely referred to as the 'big blue blob'. The role played by the extreme surface heat loss in the preceding winters in generating this feature and it subsequent evolution through winter 2015-16 will be explored.

Changes in Wine Ethanol Content Due to Evaporation from Wine Glasses and Implications for Sensory Analysis.

PubMed

Wollan, David; Pham, Duc-Truc; Wilkinson, Kerry Leigh

2016-10-12

The relative proportion of water and ethanol present in alcoholic beverages can significantly influence the perception of wine sensory attributes. This study therefore investigated changes in wine ethanol concentration due to evaporation from wine glasses. The ethanol content of commercial wines exposed to ambient conditions while in wine glasses was monitored over time. No change in wine ethanol content was observed where glasses were covered with plastic lids, but where glasses were not covered, evaporation had a significant impact on wine ethanol content, with losses from 0.9 to 1.9% alcohol by volume observed for wines that received direct exposure to airflow for 2 h. Evaporation also resulted in decreases in the concentration of some fermentation volatiles (determined by gas chromatography-mass spectrometry) and a perceptible change in wine aroma. The rate of ethanol loss was strongly influenced by exposure to airflow (i.e., from the laboratory air-conditioning unit), together with certain glass shape and wine parameters; glass headspace in particular. This is the first study to demonstrate the significant potential for ethanol evaporation from wine in wine glasses. Research findings have important implications for the technical evaluation of wine sensory properties; in particular, informal sensory trials and wine show judging, where the use of covers on wine glasses is not standard practice.

Using reference values to define disease based on the lower limit of normal biased the population attributable fraction, but not the population excess risk: the example of chronic airflow obstruction.

PubMed

Burney, Peter; Minelli, Cosetta

2018-01-01

The impact of disease on population health is most commonly estimated by the population attributable fraction (PAF), or less commonly by the excess risk, an alternative measure that estimates the absolute risk of disease in the population that can be ascribed to the exposure. Using chronic airflow obstruction as an example, we examined the impact on these estimates of defining disease based on different "normal" values. We estimated PAF and the excess risk in scenarios in which the true rate of disease was 10% in the exposed and 5% in the unexposed, and where either 50% or 20% of the population was exposed. Disease definition was based on a "lower limit of normal", using the 5th, 1st and 0.2nd centile of values in a "normal" population as thresholds to define normality. Where normality is defined by centiles of values in a "normal" population, PAF is strongly influenced by which centile is selected to define normality. This is not true for the population excess risk. Care should be taken when interpreting estimates of PAF when disease is defined from a centile of a normal population. Copyright © 2017 Elsevier Inc. All rights reserved.

Flow separation in a computational oscillating vocal fold model

NASA Astrophysics Data System (ADS)

Alipour, Fariborz; Scherer, Ronald C.

2004-09-01

A finite-volume computational model that solves the time-dependent glottal airflow within a forced-oscillation model of the glottis was employed to study glottal flow separation. Tracheal input velocity was independently controlled with a sinusoidally varying parabolic velocity profile. Control parameters included flow rate (Reynolds number), oscillation frequency and amplitude of the vocal folds, and the phase difference between the superior and inferior glottal margins. Results for static divergent glottal shapes suggest that velocity increase caused glottal separation to move downstream, but reduction in velocity increase and velocity decrease moved the separation upstream. At the fixed frequency, an increase of amplitude of the glottal walls moved the separation further downstream during glottal closing. Increase of Reynolds number caused the flow separation to move upstream in the glottis. The flow separation cross-sectional ratio ranged from approximately 1.1 to 1.9 (average of 1.47) for the divergent shapes. Results suggest that there may be a strong interaction of rate of change of airflow, inertia, and wall movement. Flow separation appeared to be ``delayed'' during the vibratory cycle, leading to movement of the separation point upstream of the glottal end only after a significant divergent angle was reached, and to persist upstream into the convergent phase of the cycle.

Air temperature gradient in large industrial hall

NASA Astrophysics Data System (ADS)

Karpuk, Michał; Pełech, Aleksander; Przydróżny, Edward; Walaszczyk, Juliusz; Szczęśniak, Sylwia

2017-11-01

In the rooms with dominant sensible heat load, volume airflow depends on many factors incl. pre-established temperature difference between exhaust and supply airflow. As the temperature difference is getting higher, airflow volume drops down, consequently, the cost of AHU is reduced. In high industrial halls with air exhaust grids located under the ceiling additional temperature gradient above working zone should be taken into consideration. In this regard, experimental research of the vertical air temperature gradient in high industrial halls were carried out for the case of mixing ventilation system The paper presents the results of air temperature distribution measurements in high technological hall (mechanically ventilated) under significant sensible heat load conditions. The supply airflow was delivered to the hall with the help of the swirl diffusers while exhaust grids were located under the hall ceiling. Basing on the air temperature distribution measurements performed on the seven pre-established levels, air temperature gradient in the area between 2.0 and 7.0 m above the floor was calculated and analysed.

Energy Harvesting from Human Motion Using Footstep-Induced Airflow

NASA Astrophysics Data System (ADS)

Fu, H.; Xu, R.; Seto, K.; Yeatman, E. M.; Kim, S. G.

2015-12-01

This paper presents an unobtrusive in-shoe energy harvester converting foot-strike energy into electricity to power wearable or portable devices. An air-pumped turbine system is developed to address the issues of the limited vertical deformation of shoes and the low frequency of human motion that impede harvesting energy from this source. The air pump is employed to convert the vertical foot-strike motion into airflow. The generated airflow passes through the miniaturized wind turbine whose transduction is realized by an electromagnetic generator. Energy is extracted from the generator with a higher frequency than that of footsteps, boosting the output power of the device. The turbine casing is specifically designed to enable the device to operate continuously with airflow in both directions. A prototype was fabricated and then tested under different situations. A 6 mW peak power output was obtained with a 4.9 Ω load. The achievable power from this design was estimated theoretically for understanding and further improvement.

Does air gas aesthesiometry generate a true mechanical stimulus for corneal sensitivity measurement?

PubMed

Nosch, Daniela S; Pult, Heiko; Albon, Julie; Purslow, Christine; Murphy, Paul J

2018-03-01

Belmonte Ocular Pain Meter (OPM) air jet aesthesiometry overcomes some of the limitations of the Cochet-Bonnet aesthesiometer. However, for true mechanical corneal sensitivity measurement, the airflow stimulus temperature of the aesthesiometer must equal ocular surface temperature (OST), to avoid additional response from temperature-sensitive nerves. The aim of this study was to determine: (A) the stimulus temperature inducing no or least change in OST; and (B) to evaluate if OST remains unchanged with different stimulus durations and airflow rates. A total of 14 subjects (mean age 25.14 ± 2.18 years; seven women) participated in this clinical cohort study: (A) OST was recorded using an infrared camera (FLIR A310) during the presentation of airflow stimuli, at five temperatures, ambient temperature (AT) +5°C, +10°C, +15°C, +20°C and +30°C, using the OPM aesthesiometer (duration three seconds; over a four millimetre distance; airflow rate 60 ml/min); and (B) OST measurements were repeated with two stimulus temperatures (AT +10°C and +15°C) while varying stimulus durations (three seconds and five seconds) and airflow rates (30, 60, 80 and 100 ml/min). Inclusion criteria were age <40 years, no contact lens wear, absence of ocular disease including dry eye, and no use of artificial tears. Repeated measures (analysis of variance) and appropriate post-hoc t-tests were applied. (A) Stimulus temperatures of AT +10°C and +15°C induced the least changes in OST (-0.20 ± 0.13°C and 0.08 ± 0.05°C). (B) OST changes were statistically significant with both stimulus temperatures and increased with increasing airflow rates (p < 0.001), and were more marked with stimulus temperature AT +10°C. A true mechanical threshold for corneal sensitivity cannot be established with the air stimulus of the Belmonte OPM because its air jet stimulus with mechanical setting is likely to have a thermal component. Appropriate stimulus selection for an air jet aesthesiometer must incorporate stimulus temperature control that can vary with stimulus duration and airflow rate. © 2017 Optometry Australia.

Resistance to airflow through bedding materials used in infancy.

PubMed Central

Hatch, D J; Helms, P; Matthew, D J; Skinner, D

1982-01-01

Various bedding materials used in infancy, including duvets (or continental quilts), were tested for airflow using the British Standards Institution tests for pillows or fabrics. Resistance was also measured when the items were placed on a dummy infant face. Measurements were made on washed and unwashed garments, which were tested both dry and wet. Results suggest that all the bedding materials tested are safe for use even in the newborn period. The duvets produced slightly lower resistance to breathing than conventional blankets and sheets. In view of the wide variety of infant bedding fabrics it seems desirable for standard airflow performance requirements to be introduced. PMID:7092309

Two-dimensional airflow modeling underpredicts the wind velocity over dunes

PubMed Central

Michelsen, Britt; Strobl, Severin; Parteli, Eric J. R.; Pöschel, Thorsten

2015-01-01

We investigate the average turbulent wind field over a barchan dune by means of Computational Fluid Dynamics. We find that the fractional speed-up ratio of the wind velocity over the three-dimensional barchan shape differs from the one obtained from two-dimensional calculations of the airflow over the longitudinal cut along the dune’s symmetry axis — that is, over the equivalent transverse dune of same size. This finding suggests that the modeling of the airflow over the central slice of barchan dunes is insufficient for the purpose of the quantitative description of barchan dune dynamics as three-dimensional flow effects cannot be neglected. PMID:26572966

21 CFR 874.3900 - Nasal dilator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nasal dilator. 874.3900 Section 874.3900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES... nasal airflow. The device decreases airway resistance and increases nasal airflow. The external nasal...

21 CFR 874.3900 - Nasal dilator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nasal dilator. 874.3900 Section 874.3900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES... nasal airflow. The device decreases airway resistance and increases nasal airflow. The external nasal...

The construction of ventilation turrets in Atta vollenweideri leaf-cutting ants: Carbon dioxide levels in the nest tunnels, but not airflow or air humidity, influence turret structure

PubMed Central

Roces, Flavio

2017-01-01

Nest ventilation in the leaf-cutting ant Atta vollenweideri is driven via a wind-induced mechanism. On their nests, workers construct small turrets that are expected to facilitate nest ventilation. We hypothesized that the construction and structural features of the turrets would depend on the colony’s current demands for ventilation and thus might be influenced by the prevailing environmental conditions inside the nest. Therefore, we tested whether climate-related parameters, namely airflow, air humidity and CO2 levels in the outflowing nest air influenced turret construction in Atta vollenweideri. In the laboratory, we simulated a semi-natural nest arrangement with fungus chambers, a central ventilation tunnel providing outflow of air and an aboveground building arena for turret construction. In independent series, different climatic conditions inside the ventilation tunnel were experimentally generated, and after 24 hours, several features of the built turret were quantified, i.e., mass, height, number and surface area (aperture) of turret openings. Turret mass and height were similar in all experiments even when no airflow was provided in the ventilation tunnel. However, elevated CO2 levels led to the construction of a turret with several minor openings and a larger total aperture. This effect was statistically significant at higher CO2 levels of 5% and 10% but not at 1% CO2. The construction of a turret with several minor openings did not depend on the strong differences in CO2 levels between the outflowing and the outside air, since workers also built permeated turrets even when the CO2 levels inside and outside were both similarly high. We propose that the construction of turrets with several openings and larger opening surface area might facilitate the removal of CO2 from the underground nest structure and could therefore be involved in the control of nest climate in leaf-cutting ants. PMID:29145459

Per cent emphysema is associated with respiratory and lung cancer mortality in the general population: a cohort study.

PubMed

Oelsner, Elizabeth C; Carr, J Jeffrey; Enright, Paul L; Hoffman, Eric A; Folsom, Aaron R; Kawut, Steven M; Kronmal, Richard A; Lederer, David J; Lima, Joao A C; Lovasi, Gina S; Smith, Benjamin M; Shea, Steven J; Barr, R Graham

2016-07-01

Emphysema on CT is a risk factor for all-cause mortality in persons with and without airflow obstruction; however, causes of death associated with emphysema remain uncertain, particularly in the general population. To test associations between quantitatively assessed emphysema on CT and cause of death in persons with and without a substantial smoking history. The Multi-Ethnic Study of Atherosclerosis recruited 6814 participants, aged 45-84 years and without clinical cardiovascular disease, in 2000-2002. Per cent emphysema was defined on cardiac CT as per cent of lung voxels less than -950 Hounsfield units; emphysema on CT was defined as per cent emphysema above the upper limit of normal. Cause of death was classified by administrative codes. Proportional-hazards models were adjusted for age, race/ethnicity, gender, body mass index, smoking status, pack-years, coronary artery calcium, site and education. Additional adjustment for lung function was made in a subset with spirometry from 2004 to 2006. There were 1091 deaths over 12 years median follow-up. Emphysema on CT was strongly associated with increased mortality due to respiratory diseases (adjusted HR 2.94, 95% CI 1.68 to 5.15), particularly chronic lower respiratory diseases (adjusted HR 9.54, 95% CI 4.70 to 19.35), and lung cancer (adjusted HR 1.84, 95% CI 1.09 to 3.12), but not cardiovascular disease. Associations persisted among participants with fewer than 10 pack-years and those without physician-diagnosed respiratory disease, and were similar after adjustment for airflow measures and in persons without airflow limitation. Quantitatively assessed emphysema on CT is associated with greater respiratory disease and lung cancer mortality, even among persons without traditional risk factors. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

The construction of ventilation turrets in Atta vollenweideri leaf-cutting ants: Carbon dioxide levels in the nest tunnels, but not airflow or air humidity, influence turret structure.

PubMed

Halboth, Florian; Roces, Flavio

2017-01-01

Nest ventilation in the leaf-cutting ant Atta vollenweideri is driven via a wind-induced mechanism. On their nests, workers construct small turrets that are expected to facilitate nest ventilation. We hypothesized that the construction and structural features of the turrets would depend on the colony's current demands for ventilation and thus might be influenced by the prevailing environmental conditions inside the nest. Therefore, we tested whether climate-related parameters, namely airflow, air humidity and CO2 levels in the outflowing nest air influenced turret construction in Atta vollenweideri. In the laboratory, we simulated a semi-natural nest arrangement with fungus chambers, a central ventilation tunnel providing outflow of air and an aboveground building arena for turret construction. In independent series, different climatic conditions inside the ventilation tunnel were experimentally generated, and after 24 hours, several features of the built turret were quantified, i.e., mass, height, number and surface area (aperture) of turret openings. Turret mass and height were similar in all experiments even when no airflow was provided in the ventilation tunnel. However, elevated CO2 levels led to the construction of a turret with several minor openings and a larger total aperture. This effect was statistically significant at higher CO2 levels of 5% and 10% but not at 1% CO2. The construction of a turret with several minor openings did not depend on the strong differences in CO2 levels between the outflowing and the outside air, since workers also built permeated turrets even when the CO2 levels inside and outside were both similarly high. We propose that the construction of turrets with several openings and larger opening surface area might facilitate the removal of CO2 from the underground nest structure and could therefore be involved in the control of nest climate in leaf-cutting ants.

Highlighting the importance of transitional ventilation regimes in the management of Mediterranean show caves (Nerja-Pintada system, southern Spain).

PubMed

Liñán, C; Del Rosal, Y; Carrasco, F; Vadillo, I; Benavente, J; Ojeda, L

2018-08-01

This study shows the utilization of the air CO 2 exhaled by a very high number of visitors in the Nerja Cave as both a tracer and an additional tool to precisely evaluate the air circulation through the entire karst system, which includes non-touristic passages, originally free of anthropogenic CO 2 . The analysis of the temporal - spatial evolution of the CO 2 content and other monitoring data measured from January 2015 to December 2016 in the Nerja-Pintada system, including air microbiological controls, has allowed us to define a new general ventilation model, of great interest for the conservation of the subterranean environment. During the annual cycle four different ventilation regimes and two ventilation modes (UAF-mode and DAF-mode) exist which determine the significance of the anthropogenic impact within the caves. During the winter regime, the strong ventilation regime and the airflow directions from the lowest to the highest entrance (UAF-mode) contribute to the rapid elimination of anthropogenic CO 2 , and this affects the whole karstic system. During the summer regime the DAF-mode ventilation (with airflows from the highest to the lowest entrances) is activated. Although the number of visitors is maximum and the natural ventilation of the karstic system is the lowest of the annual cycle, the anthropogenic impact only affects the Tourist Galleries. The transitional ventilation regimes -spring and autumn- are the most complex of the annual cycle, with changing air-flow directions (from UAF-mode to DAF-mode and vice versa) at diurnal and poly diurnal scale, which conditions the range of the anthropogenic impact in each sector of the karst system. The activation of the DAF-mode has been observed when the temperature difference between the external and air cave is higher than 5°C. Copyright © 2018 Elsevier B.V. All rights reserved.

COPD-X Australian and New Zealand guidelines for the diagnosis and management of chronic obstructive pulmonary disease: 2017 update.

PubMed

Yang, Ian A; Brown, Juliet L; George, Johnson; Jenkins, Sue; McDonald, Christine F; McDonald, Vanessa M; Phillips, Kirsten; Smith, Brian J; Zwar, Nicholas A; Dabscheck, Eli

2017-11-20

Chronic obstructive pulmonary disease (COPD) is characterised by persistent respiratory symptoms and chronic airflow limitation, and is associated with exacerbations and comorbidities. Advances in the management of COPD are updated quarterly in the national COPD guidelines, the COPD-X plan, published by Lung Foundation Australia in conjunction with the Thoracic Society of Australia and New Zealand and available at http://copdx.org.au. Main recommendations: Spirometry detects persistent airflow limitation (post-bronchodilator FEV1/FVC < 0.7) and must be used to confirm the diagnosis.Non-pharmacological and pharmacological therapies should be considered as they optimise function (ie, improve symptoms and quality of life) and prevent deterioration (ie, prevent exacerbations and reduce decline).Pulmonary rehabilitation and regular exercise are highly beneficial and should be provided to all symptomatic COPD patients.Short- and long-acting inhaled bronchodilators and, in more severe disease, anti-inflammatory agents (inhaled corticosteroids) should be considered in a stepwise approach.Given the wide range of inhaler devices available, inhaler technique and adherence should be checked regularly.Smoking cessation is essential, and influenza and pneumococcal vaccinations reduce the risk of exacerbations.A plan of care should be developed with the multidisciplinary team. COPD action plans reduce hospitalisations and are recommended as part of COPD self-management.Exacerbations should be managed promptly with bronchodilators, corticosteroids and antibiotics as appropriate to prevent hospital admission and delay COPD progression.Comorbidities of COPD require identification and appropriate management.Supportive, palliative and end-of-life care are beneficial for patients with advanced disease.Education of patients, carers and clinicians, and a strong partnership between primary and tertiary care, facilitate evidence-based management of COPD. Changes in management as result of the guideline: Spirometry remains the gold standard for diagnosing airflow obstruction and COPD. Non-pharmacological and pharmacological treatment should be used in a stepwise fashion to control symptoms and reduce exacerbation risk.

Fabrication of a polyvinylidene difluoride fiber with a metal core and its application as directional air flow sensor

NASA Astrophysics Data System (ADS)

Bian, Yixiang; Liu, Rongrong; Hui, Shen

2016-09-01

We fabricated a sensitive air flow detector that mimic the sensing mechanism found at the tail of some insects. [see Y. Yang, A. Klein, H. Bleckmann and C. Liu, Appl. Phys. Lett. 99(2) (2011); J. J. Heys, T. Gedeon, B. C. Knott and Y. Kim, J. Biomech. 41(5), 977 (2008); J. Tao and X. Yu, Smart Mat. Struct. 21(11) (2012)]. Our bionic airflow sensor uses a polyvinylidene difluoride (PVDF) microfiber with a molybdenum core which we produced with the hot extrusion tensile method. The surface of the fiber is partially coated with conductive silver adhesive that serve as surface electrodes. A third electrode, the metal core is used to polarize polyvinylidene difluoride (PVDF) under the surface electrodes. The cantilever beam structure of the prepared symmetric electrodes of metal core piezoelectric fiber (SMPF) is used as the artificial hair airflow sensor. The surface electrodes are used to measure output voltage. Our theoretical and experimental results show that the SMPF responds fast to air flow changes, the output charge has an exponential correlation with airflow velocity and a cosine relation with the direction of airflow. Our bionic airflow sensor with directional sensing ability can also measure air flow amplitude. [see H. Droogendijk, R. G. P. Sanders and G. J. M. Krijnen, New J. Phys. 15 (2013)]. By using two surface electrodes, our sensing circuit further improves sensitivity.

Spray drying of budesonide, formoterol fumarate and their composites-II. Statistical factorial design and in vitro deposition properties.

PubMed

Tajber, L; Corrigan, O I; Healy, A M

2009-02-09

The aim of this study was to investigate the effect of changing spray drying parameters on the production of a budesonide/formoterol fumarate 100:6 (w/w) composite. The systems were spray dried as solutions from 95% ethanol/5% water (v/v) using a Büchi 191-Mini Spray Dryer. A 2(5-1) factorial design study was undertaken to assess the consequence of altering spray drying processing variables on particle characteristics. The processing parameters that were studied were inlet temperature, spray drier airflow rate, pump rate, aspirator setting and feed concentration. Each batch of the resulting powder was characterised in terms of thermal and micromeritic properties as well as an in vitro deposition by twin impinger analysis. Overall, the parameter that had the greatest influence on each response investigated was production yield - airflow (higher airflow giving greater yields), median particle size - airflow (higher airflow giving smaller particle sizes) and Carr's compressibility index - feed concentration (lower feed concentration giving smaller Carr's indices). A six- to seven-fold difference in respirable fraction can be observed by changing the spray drying process parameters. The co-spray dried composite system which displayed best in vitro deposition characteristics, showed a 2.6-fold increase in respirable fraction in the twin impinger experiments and better dose uniformity compared with the physical mix of micronised powders.

Detection of Mouse Cough Based on Sound Monitoring and Respiratory Airflow Waveforms

PubMed Central

Chen, Liyan; Lai, Kefang; Lomask, Joseph Mark; Jiang, Bert; Zhong, Nanshan

2013-01-01

Detection for cough in mice has never yielded clearly audible sounds, so there is still a great deal of debates as to whether mice can cough in response to tussive stimuli. Here we introduce an approach for detection of mouse cough based on sound monitoring and airflow signals. 40 Female BALB/c mice were pretreated with normal saline, codeine, capasazepine or desensitized with capsaicin. Single mouse was put in a plethysmograph, exposed to aerosolized 100 µmol/L capsaicin for 3 min, followed by continuous observation for 3 min. Airflow signals of total 6 min were recorded and analyzed to detect coughs. Simultaneously, mouse cough sounds were sensed by a mini-microphone, monitored manually by an operator. When manual and automatic detection coincided, the cough was positively identified. Sound and sound waveforms were also recorded and filtered for further analysis. Body movements were observed by operator. Manual versus automated counts were compared. Seven types of airflow signals were identified by integrating manual and automated monitoring. Observation of mouse movements and analysis of sound waveforms alone did not produce meaningful data. Mouse cough numbers decreased significantly after all above drugs treatment. The Bland-Altman and consistency analysis between automatic and manual counts was 0.968 and 0.956. The study suggests that the mouse is able to present with cough, which could be detected by sound monitoring and respiratory airflow waveform changes. PMID:23555643

Reconstructing atmospheric circulation over southern New Zealand: Establishment of modern westerly airflow 5500 years ago and implications for Southern Hemisphere Holocene climate change

NASA Astrophysics Data System (ADS)

Turney, C. S. M.; Wilmshurst, J. M.; Jones, R. T.; Wood, J. R.; Palmer, J. G.; Hogg, A. G.; Fenwick, P.; Crowley, S. F.; Privat, K.; Thomas, Z.

2017-03-01

Late-twentieth century changes in the intensity and migration of Southern Hemisphere westerly winds have been implicated in spatially complex variability in atmospheric and ocean circulation, and ice-sheet dynamics, across the mid- to high-latitudes. A major uncertainty, however, is whether present day hemispheric-wide symmetrical airflow is representative of past behaviour. Here we report a multi-proxy study from Stewart Island and southern Fiordland, New Zealand (46-47°S) reconstructing Holocene changes at the northern limit of westerly airflow. Increased minerogenic input and a pronounced shift in cool-loving vegetation around 5500 years ago is consistent with the establishment of westerly airflow at this latitude in the southwest Pacific. In marked contrast, stronger winds are reported further south over the subantarctic Auckland (50°S) and Campbell (52°S) Islands from 8000 years ago. Intriguingly, reconstructions from the east Pacific suggest a weakening of core westerly airflow after 8500 years ago, but an expansion along the northern limits sometime after 5500 years ago. Our results suggest similar atmospheric circulation changes have been experienced in the Pacific since 5500 years ago, but indicate an expanded network of sites is needed to comprehensively test the driver(s) and impact(s) of Holocene mid-latitude westerly winds across the Southern Hemisphere.

Computational fluid dynamics (CFD) investigation of impacts of an obstruction on airflow in underground mines.

PubMed

Zhou, L; Goodman, G; Martikainen, A

2013-01-01

Continuous airflow monitoring can improve the safety of the underground work force by ensuring the uninterrupted and controlled distribution of mine ventilation to all working areas. Air velocity measurements vary significantly and can change rapidly depending on the exact measurement location and, in particular, due to the presence of obstructions in the air stream. Air velocity must be measured at locations away from obstructions to avoid the vortices and eddies that can produce inaccurate readings. Further, an uninterrupted measurement path cannot always be guaranteed when using continuous airflow monitors due to the presence of nearby equipment, personnel, roof falls and rib rolls. Effective use of these devices requires selection of a minimum distance from an obstacle, such that an air velocity measurement can be made but not affected by the presence of that obstacle. This paper investigates the impacts of an obstruction on the behavior of downstream airflow using a numerical CFD model calibrated with experimental test results from underground testing. Factors including entry size, obstruction size and the inlet or incident velocity are examined for their effects on the distributions of airflow around an obstruction. A relationship is developed between the minimum measurement distance and the hydraulic diameters of the entry and the obstruction. A final analysis considers the impacts of continuous monitor location on the accuracy of velocity measurements and on the application of minimum measurement distance guidelines.

Computational fluid dynamics (CFD) investigation of impacts of an obstruction on airflow in underground mines

PubMed Central

Zhou, L.; Goodman, G.; Martikainen, A.

2015-01-01

Continuous airflow monitoring can improve the safety of the underground work force by ensuring the uninterrupted and controlled distribution of mine ventilation to all working areas. Air velocity measurements vary significantly and can change rapidly depending on the exact measurement location and, in particular, due to the presence of obstructions in the air stream. Air velocity must be measured at locations away from obstructions to avoid the vortices and eddies that can produce inaccurate readings. Further, an uninterrupted measurement path cannot always be guaranteed when using continuous airflow monitors due to the presence of nearby equipment, personnel, roof falls and rib rolls. Effective use of these devices requires selection of a minimum distance from an obstacle, such that an air velocity measurement can be made but not affected by the presence of that obstacle. This paper investigates the impacts of an obstruction on the behavior of downstream airflow using a numerical CFD model calibrated with experimental test results from underground testing. Factors including entry size, obstruction size and the inlet or incident velocity are examined for their effects on the distributions of airflow around an obstruction. A relationship is developed between the minimum measurement distance and the hydraulic diameters of the entry and the obstruction. A final analysis considers the impacts of continuous monitor location on the accuracy of velocity measurements and on the application of minimum measurement distance guidelines. PMID:26388684

Bacterial burden in the operating room: impact of airflow systems.

PubMed

Hirsch, Tobias; Hubert, Helmine; Fischer, Sebastian; Lahmer, Armin; Lehnhardt, Marcus; Steinau, Hans-Ulrich; Steinstraesser, Lars; Seipp, Hans-Martin

2012-09-01

Wound infections present one of the most prevalent and frequent complications associated with surgical procedures. This study analyzes the impact of currently used ventilation systems in the operating room to reduce bacterial contamination during surgical procedures. Four ventilation systems (window-based ventilation, supported air nozzle canopy, low-turbulence displacement airflow, and low-turbulence displacement airflow with flow stabilizer) were analyzed. Two hundred seventy-seven surgical procedures in 6 operating rooms of 5 different hospitals were analyzed for this study. Window-based ventilation showed the highest intraoperative contamination (13.3 colony-forming units [CFU]/h) followed by supported air nozzle canopy (6.4 CFU/h; P = .001 vs window-based ventilation) and low-turbulence displacement airflow (3.4 and 0.8 CFU/h; P < .001 vs window-based ventilation and supported air nozzle canopy). The highest protection was provided by the low-turbulence displacement airflow with flow stabilizer (0.7 CFU/h), which showed a highly significant difference compared with the best supported air nozzle canopy theatre (3.9 CFU/h; P < .001). Furthermore, this system showed no increase of contamination in prolonged durations of surgical procedures. This study shows that intraoperative contamination can be significantly reduced by the use of adequate ventilation systems. Copyright © 2012 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Optical intensity scintillation in the simulated atmospherical environment

NASA Astrophysics Data System (ADS)

Hajek, Lukas; Latal, Jan; Vanderka, Ales; Vitasek, Jan; Bojko, Marian; Bednarek, Lukas; Vasinek, Vladimir

2016-09-01

There are several parameters of the atmospheric environment which have an effect on the optical wireless connection. Effects like fog, snow or rain are ones of the effects which appears tendentiously and which are bound by season, geographic location, etc. One of the effects that appear with various intensity for the whole time is airflow. The airflow changes the local refractive index of the air and areas with lower or higher refractive index form. The light going through these areas refracts and due to the optical intensity scintillates on the detector of the receiver. The airflow forms on the basis of two effects in the atmosphere. The first is wind cut and flowing over barriers. The other is thermal flow when warm air rises to the higher layers of the atmosphere. The heart of this article is creation such an environment that will form airflow and the refractive index will scintillate. For the experiment, we used special laboratory box with high-speed ventilators and heating units to simulate atmospheric turbulence. We monitor the impact of ventilator arrangement and air temperature on the scintillation of the gas laser with wavelength 633 nm/15 mW. In the experiment, there is watched the difference in behavior between real measurement and flow simulation with the same peripheral conditions of the airflow in the area of 500 x 500 cm.

ENVIRONMENTAL TECHNOLOGY VERIFICATION, TEST REPORT OF CONTROL OF BIOAEROSOLS IN HVAC SYSTEMS, AIRFLOW PRODUCTS AFP30

EPA Science Inventory

The Environmental Technology Verification report discusses the technology and performance of the AFP30 air filter for dust and bioaerosol filtration manufactured by Airflow Products. The pressure drop across the filter was 62 Pa clean and 247 Pa dust loaded. The filtration effici...

Foehn-induced effects on dust pollution, frontal clouds and solar radiation in the Dead Sea valley

NASA Astrophysics Data System (ADS)

Kishcha, Pavel; Starobinets, Boris; Alpert, Pinhas; Kaplan, Michael

2017-04-01

The significant drying up of the Dead Sea over the past 40 years has led to an increase in an exposed area contributing to local dust pollution. Measurements show that, sometimes, in the Dead Sea valley, dust pollution can reach extreme concentrations up to several thousands of micrograms per cubic meters. Our analysis of a meteorological situation shows that a foehn phenomenon can be a causal factor for the aforementioned extreme local dust concentration. This foehn phenomenon creates strong warm and dry winds, which are accompanied by air turbulence and temperature inversion. In our study, foehn-induced effects on dust pollution, frontal clouds and solar radiation were analyzed over the Judean Mountains ( 1000 m) and over the Dead Sea valley (-420 m), using high-resolution numerical simulations and in-situ observations at meteorological stations located across the mountain ridge. An extreme dust episode occurring on March 22, 2013, was analyzed, which was characterized by measured surface dust concentrations of up to 7000 µg m-3 in the Dead Sea valley. We simulated this foehn phenomenon with the 3-km resolution COSMO-ART model. Our analysis has shown that the foehn phenomenon could be observed even over the relatively low Judean Mountains. This analysis was based on various meteorological, pyranometer, radar, and aerosol measurements together with high-resolution model data. In the Dead Sea valley, the maximum aerosol optical depth (AOD) did not coincide with the maximum surface dust concentration. This lack of coincidence indicates difficulties in using satellite-based AOD for initializing dust concentration within numerical forecast systems over this region with complex terrain. In the western Dead Sea valley, strong foehn winds of over 20 m/s were accompanied by maximal air turbulence leading to maximal local dust emissions. Thus, the model showed that, by creating significant turbulence, the foehn phenomenon intensified the saltation (bombardment) mechanism of local dust generation in the western Dead Sea valley. In addition, the foehn-induced pronounced temperature inversion trapped dust particles beneath this inversion. These two factors caused the measured extreme surface dust concentration in the Dead Sea valley on the specified day. Radar data on March 22 showed a passage of multi-layer frontal cloudiness through the area of the Dead Sea valley leading to a sharp drop in noon solar radiation. The strong descending airflow over the downwind side of the Judean Mountains significantly influenced the frontal cloudiness leading to the formation of a cloud-free band over the Dead Sea valley.

Flow volume loops in patients with goiters.

PubMed Central

Geraghty, J G; Coveney, E C; Kiernan, M; O'Higgins, N J

1992-01-01

Plain radiology is the standard means of assessing upper airway obstruction in patients with goiters. Flow volume loop curves will provide additional information, because they allow a quantitative assessment of airflow dynamics in the respiratory cycle. Fifty-one patients had flow volume loops performed before and after thyroidectomy. There was a significant increase in the maximum inspiratory flow rate (3.9 +/- 0.2 versus 4.9 +/- 0.2 L/second, p less than 0.01) after thyroidectomy. Eight of twelve patients with normal tracheal radiology had improved airflow dynamics in the postoperative period. The flow volume loop curve is a simple noninvasive means of assessing airflow dynamics in patients with goiters and may be superior to conventional radiology. PMID:1731653

A Comparative Study of Airflow and Odorant Deposition in the Mammalian Nasal Cavity

NASA Astrophysics Data System (ADS)

Richter, Joseph; Rumple, Christopher; Ranslow, Allison; Quigley, Andrew; Pang, Benison; Neuberger, Thomas; Krane, Michael; van Valkenburgh, Blaire; Craven, Brent

2013-11-01

The complex structure of the mammalian nasal cavity provides a tortuous airflow path and a large surface area for respiratory air conditioning, filtering of inspired contaminants, and olfaction. Due to the small and contorted structure of the nasal turbinals, nasal anatomy and function remains poorly understood in most mammals. Here, we utilize high-resolution MRI scans to reconstruct anatomically-accurate models of the mammalian nasal cavity. These data are used to compare the form and function of the mammalian nose. High-fidelity computational fluid dynamics (CFD) simulations of nasal airflow and odorant deposition are presented and used to compare olfactory function across species (primate, rodent, canine, feline, ungulate).

[Midface alterations in childhood as pathogenesis of obstructive sleep apnea syndrome].

PubMed

Rangel Chávez, José de Jesús; Espinosa Martínez, Cynthia; Medina Serpa, Aldo Uzziel

The onset of nasal breathing sets a genetically determined impulse to aerate the face cavities or paranasal sinuses, which in turn initiate its growth creating the useful trafficable space for air during the development of the midface. Considering the evidence that the upper airway obstruction has a primary role in the pathogenesis of respiratory sleep disorders, any condition that causes a permanent difficulty to the nasal airflow during breathing will cause hypo-development of the required amplitude in this airway, reducing the growth stimulation of the sinus cavities and altering the development of the midface as a whole. Copyright © 2016 Hospital Infantil de México Federico Gómez. Publicado por Masson Doyma México S.A. All rights reserved.

42 CFR 84.1149 - Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements. 84.1149 Section 84.1149 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF...

42 CFR 84.1149 - Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements. 84.1149 Section 84.1149 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF...

42 CFR 84.1149 - Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements. 84.1149 Section 84.1149 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF...

42 CFR 84.1149 - Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements. 84.1149 Section 84.1149 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF...

42 CFR 84.1149 - Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Airflow resistance tests; all dust, fume, and mist respirators; minimum requirements. 84.1149 Section 84.1149 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF...

Site, environmental and airflow characteristics for mono-slope beef cattle facilities in the Northern Great Plains

USDA-ARS?s Scientific Manuscript database

In conjunction with an emission monitoring study, long-term airflow and environmental data were collected from four regional producer-owned and -operated mono-slope beef cattle facilities in the Northern Great Plains. The barns were oriented east-west, with approximate dimensions of an 8-m south wal...

42 CFR 84.156 - Airflow resistance test; Type C supplied-air respirator, demand class; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... C supplied-air respirator, demand class; minimum requirements. (a) Inhalation resistance shall not... 42 Public Health 1 2010-10-01 2010-10-01 false Airflow resistance test; Type C supplied-air respirator, demand class; minimum requirements. 84.156 Section 84.156 Public Health PUBLIC HEALTH SERVICE...

Test-Retest Reliability of Respiratory Resistance Measured with the Airflow Perturbation Device

ERIC Educational Resources Information Center

Gallena, Sally K.; Solomon, Nancy Pearl; Johnson, Arthur T.; Vossoughi, Jafar; Tian, Wei

2014-01-01

Purpose: In this study, the authors aimed to determine reliability of the airflow perturbation device (APD) to measure respiratory resistance within and across sessions during resting tidal (RTB) and postexercise breathing in healthy athletes, and during RTB across trials within a session in athletes with paradoxical vocal fold motion (PVFM)…

42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

Code of Federal Regulations, 2012 CFR

2012-10-01

... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2012-10-01 2012-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH...

42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

Code of Federal Regulations, 2013 CFR

2013-10-01

... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2013-10-01 2013-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH...

42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

Code of Federal Regulations, 2014 CFR

2014-10-01

... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2014-10-01 2014-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH...

42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

Code of Federal Regulations, 2010 CFR

2010-10-01

... respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... the facepiece shall not fall below atmospheric at inhalation airflows less than 115 liters (4 cubic...

42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

Code of Federal Regulations, 2011 CFR

2011-10-01

... respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... the facepiece shall not fall below atmospheric at inhalation airflows less than 115 liters (4 cubic...

Dust control by air-blocking shelves and dust collector-to-bailing airflow ratios for a surface mine drill shroud

PubMed Central

Zheng, Y.; Reed, W.R.; Potts, J.D.; Li, M.; Rider, J.P.

2018-01-01

The National Institute for Occupational Safety and Health (NIOSH) recently developed a series of validated models utilizing computational fluid dynamics (CFD) to study the effects of air-blocking shelves on airflows and respirable dust distribution associated with medium-sized surface blasthole drill shrouds as part of a dry dust collector system. Using validated CFD models, three different air-blocking shelves were included in the present study: a 15.2-cm (6-in.)-wide shelf; a 7.6-cm (3-in.)-wide shelf; and a 7.6-cm (3-in.)-wide shelf at four different shelf heights. In addition, the dust-collector-to-bailing airflow ratios of 1.75:1, 1.5:1, 1.25:1 and 1:1 were evaluated for the 15.2-cm (6-in.)-wide air-blocking shelf. This paper describes the methodology used to develop the CFD models. The effects of air-blocking shelves and dust collector-to-bailing airflow ratios were identified by the study, and problem regions were revealed under certain conditions.

A Hot-Polymer Fiber Fabry–Perot Interferometer Anemometer for Sensing Airflow

PubMed Central

Lee, Cheng-Ling; Liu, Kai-Wen; Luo, Shi-Hong; Wu, Meng-Shan; Ma, Chao-Tsung

2017-01-01

This work proposes the first hot-polymer fiber Fabry–Perot interferometer (HPFFPI) anemometer for sensing airflow. The proposed HPFFPI is based on a single-mode fiber (SMF) endface that is attached to a UV-cured polymer to form an ultracompact fiber Fabry–Perot microcavity. The proposed polymer microcavity was heated using a low-cost chip resistor with a controllable dc driving power to achieve a desired polymer’s steady-state temperature (T) that exceeds the T of the surrounding environment. The polymer is highly sensitive to variations of T with high repeatability. When the hot polymer was cooled by the measured flowing air, the wavelength fringes of its optical spectra shifted. The HPFFPI anemometers have been experimentally evaluated for different cavity lengths and heating power values. Experimental results demonstrate that the proposed HPFFPI responses well in terms of airflow measurement. A high sensitivity of 1.139 nm/(m/s) and a good resolution of 0.0088 m/s over the 0~2.54 m/s range of airflow were achieved with a cavity length of 10 μm and a heating power of 0.402 W. PMID:28869510

The effects of a hot drink on nasal airflow and symptoms of common cold and flu.

PubMed

Sanu, A; Eccles, R

2008-12-01

Hot drinks are a common treatment for common cold and flu but there are no studies reported in the scientific and clinical literature on this mode of treatment. This study investigated the effects of a hot fruit drink on objective and subjective measures of nasal airflow, and on subjective scores for common cold/flu symptoms in 30 subjects suffering from common cold/flu. The results demonstrate that the hot drink had no effect on objective measurement of nasal airflow but it did cause a significant improvement in subjective measures of nasal airflow. The hot drink provided immediate and sustained relief from symptoms of runny nose, cough, sneezing, sore throat, chilliness and tiredness, whereas the same drink at room temperature only provided relief from symptoms of runny nose, cough and sneezing. The effects of the drinks are discussed in terms of a placebo effect and physiological effects on salivation and airway secretions. In conclusion the results support the folklore that a hot tasty drink is a beneficial treatment for relief of most symptoms of common cold and flu.

Performance power evaluation of DC fan cooling system for PV panel by using ANSYS CFX

NASA Astrophysics Data System (ADS)

Syafiqah, Z.; Amin, N. A. M.; Irwan, Y. M.; Irwanto, M.; Leow, W. Z.; Amelia, A. R.

2017-09-01

A research has been conducted to find the optimum combination for DC fan air cooling system of photovoltaic (PV) panel. During normal operation of PV panel, it is estimated that only 15 % of solar radiation is converted into electrical energy. Meanwhile, the rest of the solar radiation is converted into heat energy which affects the performance of the PV panel. Therefore, the aim of this research is to investigate the performance power evaluation of DC fan cooling system for PV panel by using ANSYS CFX. The effect of airflow configuration of DC fan has been investigated. This is to analyze whether the airflow circulation of DC fan cause a change towards the maximum temperature of PV panel. Besides, the impact of varying number of DC fans attached at the back of PV panel is evaluated. The result of airflow circulation of DC fan has been discussed. Meanwhile, with the increment number of DC fans, the PV panel temperature drops significantly. As a conclusion, the optimum number of DC fans is two with the combination of inlet airflow.

Characterization of Pump-Induced Acoustics in Space Launch System Main Propulsion System Liquid Hydrogen Feedline Using Airflow Test Data

NASA Technical Reports Server (NTRS)

Eberhart, C. J.; Snellgrove, L. M.; Zoladz, T. F.

2015-01-01

High intensity acoustic edgetones located upstream of the RS-25 Low Pressure Fuel Turbo Pump (LPFTP) were previously observed during Space Launch System (STS) airflow testing of a model Main Propulsion System (MPS) liquid hydrogen (LH2) feedline mated to a modified LPFTP. MPS hardware has been adapted to mitigate the problematic edgetones as part of the Space Launch System (SLS) program. A follow-on airflow test campaign has subjected the adapted hardware to tests mimicking STS-era airflow conditions, and this manuscript describes acoustic environment identification and characterization born from the latest test results. Fluid dynamics responsible for driving discrete excitations were well reproduced using legacy hardware. The modified design was found insensitive to high intensity edgetone-like discretes over the bandwidth of interest to SLS MPS unsteady environments. Rather, the natural acoustics of the test article were observed to respond in a narrowband-random/mixed discrete manner to broadband noise thought generated by the flow field. The intensity of these responses were several orders of magnitude reduced from those driven by edgetones.

Elasto-Aerodynamics-Driven Triboelectric Nanogenerator for Scavenging Air-Flow Energy.

PubMed

Wang, Shuhua; Mu, Xiaojing; Wang, Xue; Gu, Alex Yuandong; Wang, Zhong Lin; Yang, Ya

2015-10-27

Efficient scavenging the kinetic energy from air-flow represents a promising approach for obtaining clean, sustainable electricity. Here, we report an elasto-aerodynamics-driven triboelectric nanogenerator (TENG) based on contact electrification. The reported TENG consists of a Kapton film with two Cu electrodes at each side, fixed on two ends in an acrylic fluid channel. The relationship between the TENG output power density and its fluid channel dimensions is systematically studied. TENG with a fluid channel size of 125 × 10 × 1.6 mm(3) delivers the maximum output power density of about 9 kW/m(3) under a loading resistance of 2.3 MΩ. Aero-elastic flutter effect explains the air-flow induced vibration of Kapton film well. The output power scales nearly linearly with parallel wiring of multiple TENGs. Connecting 10 TENGs in parallel gives an output power of 25 mW, which allows direct powering of a globe light. The TENG is also utilized to scavenge human breath induced air-flow energy to sustainably power a human body temperature sensor.

Laryngeal aerodynamics associated with oral contraceptive use: preliminary findings.

PubMed

Gorham-Rowan, Mary; Fowler, Linda

2009-01-01

The purpose of this study was to examine possible differences in laryngeal aerodynamic measures during connected speech associated with oral contraceptive (OC) use. Eight women taking an OC, and eight others not taking an OC, participated in the study. Three trials of syllable /p/repetitions were obtained using a circumferentially vented face mask and small translabial tube. All participants were recorded on or near days 7 and 14 of their menstrual cycle. Subglottal pressure (P(SG)) and average airflow rates were obtained to determine laryngeal airway resistance. Glottal airflow measures of peak flow, minimum flow, alternating flow, as well as relative sound level (RSL) were obtained. P(SG) was obtained from the pressure peak associated with/p/. All airflow parameters and RSL were obtained from the vowel portion. No significant differences were found related to day of recording or OC use, indicating that OC use does not significantly affect laryngeal airflow regulation. The reader will better understand the effects of hormones and oral contraceptives on the female voice, as well as the specific changes in vocal function that may occur in conjunction with the use of oral contraceptives.

Three-Dimensional Numerical Simulation of Airflow in Nasopharynx.

NASA Astrophysics Data System (ADS)

Shome, Biswadip; Wang, Lian-Ping; Santare, Michael H.; Szeri, Andras Z.; Prasad, Ajay K.; Roberts, David

1996-11-01

A three-dimensional numerical simulation of airflow in nasopharynx (from the soft palate to the epiglottis) was conducted, using anatomically accurate model and finite element method, to study the influence of flow characteristics on obstructive sleep apnea (OSA). The results showed that the pressure drop in the nasopharynx is in the range 200-500 Pa. Ten different nasopharynx geometries resulting from three OSA treatment therapies (CPAP, mandibular repositioning devices, and surgery) were compared. The results confirmed that the airflow in the nasopharynx lies in the transitional flow regime and thus, a subtle change in the morphology caused by these treatment therapies has a large effect on the airflow. The onset of turbulence can cause as much as 40% of increase in pressure drop. For the transitional flow regime, the k-ɛ turbulence model was found to be the most appropriate model, when compared to the mixing length and the k-ω model, as it correctly reproduces the limiting laminar behavior. In addition, the pressure drop increased approximately as the square of the volumetric flow rate. Supported by NIH.

Rapid Induction of Therapeutic Hypothermia Using Transnasal High Flow Dry Air

PubMed Central

Chava, Raghuram; Raghavan, Madhavan Srinivas; Halperin, Henry; Maqbool, Farhan; Geocadin, Romergryko; Quinones-Hinojosa, Alfredo; Kolandaivelu, Aravindan; Rosen, Benjamin A.

2017-01-01

Early induction of therapeutic hypothermia (TH) is recommended in out-of-hospital cardiac arrest (CA); however, currently no reliable methods exist to initiate cooling. We investigated the effect of high flow transnasal dry air on brain and body temperatures in adult porcine animals. Adult porcine animals (n = 23) under general anesthesia were subject to high flow of transnasal dry air. Mouth was kept open to create a unidirectional airflow, in through the nostrils and out through the mouth. Brain, internal jugular, and aortic temperatures were recorded. The effect of varying airflow rate and the air humidity (0% or 100%) on the temperature profiles were recorded. The degree of brain cooling was measured as the differential temperature from baseline. A 10-minute exposure of high flow dry air caused rapid cooling of brain and gradual cooling of the jugular and the aortic temperatures in all animals. The degree of brain cooling was flow dependent and significantly higher at higher airflow rates (0.8°C ± 0.3°C, 1.03°C ± 0.6°C, and 1.3°C ± 0.7°C for 20, 40, and 80 L, respectively, p < 0.05 for all comparisons). Air temperature had minimal effect on the brain cooling over 10 minutes with similar decrease in temperature at 4°C and 30°C. At a constant flow rate (40 LPM) and temperature, the degree of cooling over 10 minutes during dry air exposure was significantly higher compared to humid air (100% saturation) (1.22°C ± 0.35°C vs. 0.21°C ± 0.12°C, p < 0.001). High flow transnasal dry air causes flow dependent cooling of the brain and the core temperatures in intubated porcine animals. The mechanism of cooling appears to be evaporation of nasal mucus as cooling is mitigated by humidifying the air. This mechanism may be exploited to initiate TH in CA. PMID:27635468

Rapid Induction of Therapeutic Hypothermia Using Transnasal High Flow Dry Air.

PubMed

Chava, Raghuram; Zviman, Menekhem; Raghavan, Madhavan Srinivas; Halperin, Henry; Maqbool, Farhan; Geocadin, Romergryko; Quinones-Hinojosa, Alfredo; Kolandaivelu, Aravindan; Rosen, Benjamin A; Tandri, Harikrishna

2017-03-01

Early induction of therapeutic hypothermia (TH) is recommended in out-of-hospital cardiac arrest (CA); however, currently no reliable methods exist to initiate cooling. We investigated the effect of high flow transnasal dry air on brain and body temperatures in adult porcine animals. Adult porcine animals (n = 23) under general anesthesia were subject to high flow of transnasal dry air. Mouth was kept open to create a unidirectional airflow, in through the nostrils and out through the mouth. Brain, internal jugular, and aortic temperatures were recorded. The effect of varying airflow rate and the air humidity (0% or 100%) on the temperature profiles were recorded. The degree of brain cooling was measured as the differential temperature from baseline. A 10-minute exposure of high flow dry air caused rapid cooling of brain and gradual cooling of the jugular and the aortic temperatures in all animals. The degree of brain cooling was flow dependent and significantly higher at higher airflow rates (0.8°C ± 0.3°C, 1.03°C ± 0.6°C, and 1.3°C ± 0.7°C for 20, 40, and 80 L, respectively, p < 0.05 for all comparisons). Air temperature had minimal effect on the brain cooling over 10 minutes with similar decrease in temperature at 4°C and 30°C. At a constant flow rate (40 LPM) and temperature, the degree of cooling over 10 minutes during dry air exposure was significantly higher compared to humid air (100% saturation) (1.22°C ± 0.35°C vs. 0.21°C ± 0.12°C, p < 0.001). High flow transnasal dry air causes flow dependent cooling of the brain and the core temperatures in intubated porcine animals. The mechanism of cooling appears to be evaporation of nasal mucus as cooling is mitigated by humidifying the air. This mechanism may be exploited to initiate TH in CA.

Low-Cost, User-Friendly, Rapid Analysis of Dynamic Data System Established

NASA Technical Reports Server (NTRS)

Arend, David J.

2004-01-01

An issue of primary importance to the development of new jet and certain other airbreathing combined-cycle powered aircraft is the advancement of airframe-integrated propulsion technologies. Namely, engine inlets and their systems and subsystems are required to capture, convert, and deliver the atmospheric airflow demanded by such engines across their operating envelope in a form that can be used to provide efficient, stable thrust. This must be done while also minimizing aircraft drag and weight. Revolutionary inlet designs aided by new technologies are needed to enable new missions. An unwanted byproduct of pursuing these inlet technologies is increased time-variant airflow distortion. Such distortions reduce propulsion system stability, performance, operability, and life. To countermand these limitations and fully evaluate the resulting configurations, best practices dictate that this distortion be experimentally measured at large scale and analyzed. The required measurements consist of those made by an array of high-response pressure transducers located in the flow field at the aerodynamic interface plane (AIP) between the inlet and engine. Although the acquisition of the necessary pitot-pressure time histories is relatively straight-forward, until recent years, the analysis has proved to be very time-consuming, tedious, and expensive. To transform the analysis of these data into a tractable and timely proposition, researchers at the NASA Glenn Research Center created and established the Rapid Analysis of Dynamic Data (RADD) system. The system provides complete, near real-time analysis of time-varying inlet airflow distortion datasets with report quality output. This fully digital approach employs Institute of Electrical and Electronics Engineers (IEEE) binary data file format standardization to establish data-acquisition-system-independent processing on low cost personal computers. Features include invalid instrumentation code-out, logging, and multiple replacement schemes as needed for each channel of instrumentation. The AIP pressure distribution can be interpolated to simulate measurements by alternate AIP probe arrays, if desired. In addition, the RADD system provides for the application of filters that can be used to focus the analysis on the frequency range of interest.

Variability among electronic cigarettes in the pressure drop, airflow rate, and aerosol production.

PubMed

Williams, Monique; Talbot, Prue

2011-12-01

This study investigated the performance of electronic cigarettes (e-cigarettes), compared different models within a brand, compared identical copies of the same model within a brand, and examined performance using different protocols. Airflow rate required to generate aerosol, pressure drop across e-cigarettes, and aerosol density were examined using three different protocols. First 10 puff protocol: The airflow rate required to produce aerosol and aerosol density varied among brands, while pressure drop varied among brands and between the same model within a brand. Total air hole area correlated with pressure drop for some brands. Smoke-out protocol: E-cigarettes within a brand generally performed similarly when puffed to exhaustion; however, there was considerable variation between brands in pressure drop, airflow rate required to produce aerosol, and the total number of puffs produced. With this protocol, aerosol density varied significantly between puffs and gradually declined. CONSECUTIVE TRIAL PROTOCOL: Two copies of one model were subjected to 11 puffs in three consecutive trials with breaks between trials. One copy performed similarly in each trial, while the second copy of the same model produced little aerosol during the third trial. The different performance properties of the two units were attributed to the atomizers. There was significant variability between and within brands in the airflow rate required to produce aerosol, pressure drop, length of time cartridges lasted, and production of aerosol. Variation in performance properties within brands suggests a need for better quality control during e-cigarette manufacture.

The difficult asthmatic.

PubMed

Gregg, I

1977-01-01

The most common reason why asthma presents difficulties in management is the failure to treat it with drugs which are appropriate and taken in adequate dosage. An understanding of the pathophysiology and aetiology of asthma is essential if full advantage is to be taken of the wide range of drugs now available for treating it. Airflow obstruction due to bronchial muscle constriction is usually readily reversible by bronchodilators, whereas that due to the inflammatory component of asthma is refractory to the latter and can only be reversed by steroids. Refractory airflow obstruction is liable to be confused with irreversible obstruction which occurs in those patients whose asthma is complicated by chronic obstructive bronchitis or other lung disease. The choice between symptomatic, preventive and suppressive forms of treatment should be made only after a careful assessment has been carried out with objective measurement of airflow obstruction. The Wright peak flow meter is unsurpassed for this purpose. By its means it should be possible to estimate how much of a patient's airflow obstruction is readily reversible, how much is refractory and how much is irreversible. In general, the aim of treatment is to relieve airflow obstruction rather than to counteract supposed aetiological factors. Both doctor and patient must understand the purpose, limitations and possible dangers of any drug which is prescribed. Steroids are the only form of treatment which is effective in persistent refractory asthma. Prejudice against steroids has resulted in many patients being deprived of their benefit, but this situation may change with the recent introduction of steroid aerosols.

DOE Office of Scientific and Technical Information (OSTI.GOV)

This study tests the performance of a variable airflow small-diameter duct heating, ventilation, and air conditioning (HVAC) system in a new construction unoccupied low-load test house in Pittsburgh, Pennsylvania. The duct system was installed entirely in conditioned space and was operated from the winter through summer seasons. Measurements were collected on the in-room temperatures and energy consumed by the air handler and heat pump unit. Operation modes with three different volumes of airflow were compared to determine the ideal airflow scenario that maximizes room-to-room thermal uniformity while minimizing fan energy consumption. Black felt infrared imagery was used as a measuremore » of diffuser throw and in-room air mixing. Measured results indicate the small-diameter, high velocity airflow system can provide comfort under some conditions. Solar heat gains resulted in southern rooms drifting beyond acceptable temperature limits. Insufficient airflow to some bedrooms also resulted in periods of potential discomfort. Homebuilders or HVAC contractors can use these results to assess whether this space conditioning strategy is an attractive alternative to a traditional duct system. The team performed a cost analysis of two duct system configurations: (1) a conventional diameter and velocity duct system, and (2) the small-diameter duct system. This work applies to both new and retrofit homes that have achieved a low heating and cooling density either by energy conservation or by operation in a mild climate with few heating or cooling degree days. Guidance is provided on cost trade-offs between the conventional duct system and the small-diameter duct system.« less

Numerical modeling of turbulent and laminar airflow and odorant transport during sniffing in the human and rat nose.

PubMed

Zhao, Kai; Dalton, Pamela; Yang, Geoffery C; Scherer, Peter W

2006-02-01

Human sniffing behavior usually involves bouts of short, high flow rate inhalation (>300 ml/s through each nostril) with mostly turbulent airflow. This has often been characterized as a factor enabling higher amounts of odorant to deposit onto olfactory mucosa than for laminar airflow and thereby aid in olfactory detection. Using computational fluid dynamics human nasal cavity models, however, we found essentially no difference in predicted olfactory odorant flux (g/cm2 s) for turbulent versus laminar flow for total nasal flow rates between 300 and 1000 ml/s and for odorants of quite different mucosal solubility. This lack of difference was shown to be due to the much higher resistance to lateral odorant mass transport in the mucosal nasal airway wall than in the air phase. The simulation also revealed that the increase in airflow rate during sniffing can increase odorant uptake flux to the nasal/olfactory mucosa but lower the cumulative total uptake in the olfactory region when the inspired air/odorant volume was held fixed, which is consistent with the observation that sniff duration may be more important than sniff strength for optimizing olfactory detection. In contrast, in rats, sniffing involves high-frequency bouts of both inhalation and exhalation with laminar airflow. In rat nose odorant uptake simulations, it was observed that odorant deposition was highly dependent on solubility and correlated with the locations of different types of receptors.

Coupling fast fluid dynamics and multizone airflow models in Modelica Buildings library to simulate the dynamics of HVAC systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Wei; Sevilla, Thomas Alonso; Zuo, Wangda

Historically, multizone models are widely used in building airflow and energy performance simulations due to their fast computing speed. However, multizone models assume that the air in a room is well mixed, consequently limiting their application. In specific rooms where this assumption fails, the use of computational fluid dynamics (CFD) models may be an alternative option. Previous research has mainly focused on coupling CFD models and multizone models to study airflow in large spaces. While significant, most of these analyses did not consider the coupled simulation of the building airflow with the building's Heating, Ventilation, and Air-Conditioning (HVAC) systems. Thismore » paper tries to fill the gap by integrating the models for HVAC systems with coupled multizone and CFD simulations for airflows, using the Modelica simul ation platform. To improve the computational efficiency, we incorporated a simplified CFD model named fast fluid dynamics (FFD). We first introduce the data synchronization strategy and implementation in Modelica. Then, we verify the implementation using two case studies involving an isothermal and a non-isothermal flow by comparing model simulations to experiment data. Afterward, we study another three cases that are deemed more realistic. This is done by attaching a variable air volume (VAV) terminal box and a VAV system to previous flows to assess the capability of the models in studying the dynamic control of HVAC systems. Finally, we discuss further research needs on the coupled simulation using the models.« less

Air trapping and airflow obstruction in newborn cystic fibrosis piglets.

PubMed

Adam, Ryan J; Michalski, Andrew S; Bauer, Christian; Abou Alaiwa, Mahmoud H; Gross, Thomas J; Awadalla, Maged S; Bouzek, Drake C; Gansemer, Nicholas D; Taft, Peter J; Hoegger, Mark J; Diwakar, Amit; Ochs, Matthias; Reinhardt, Joseph M; Hoffman, Eric A; Beichel, Reinhard R; Meyerholz, David K; Stoltz, David A

2013-12-15

Air trapping and airflow obstruction are being increasingly identified in infants with cystic fibrosis. These findings are commonly attributed to airway infection, inflammation, and mucus buildup. To learn if air trapping and airflow obstruction are present before the onset of airway infection and inflammation in cystic fibrosis. On the day they are born, piglets with cystic fibrosis lack airway infection and inflammation. Therefore, we used newborn wild-type piglets and piglets with cystic fibrosis to assess air trapping, airway size, and lung volume with inspiratory and expiratory X-ray computed tomography scans. Micro-computed tomography scanning was used to assess more distal airway sizes. Airway resistance was determined with a mechanical ventilator. Mean linear intercept and alveolar surface area were determined using stereologic methods. On the day they were born, piglets with cystic fibrosis exhibited air trapping more frequently than wild-type piglets (75% vs. 12.5%, respectively). Moreover, newborn piglets with cystic fibrosis had increased airway resistance that was accompanied by luminal size reduction in the trachea, mainstem bronchi, and proximal airways. In contrast, mean linear intercept length, alveolar surface area, and lung volume were similar between both genotypes. The presence of air trapping, airflow obstruction, and airway size reduction in newborn piglets with cystic fibrosis before the onset of airway infection, inflammation, and mucus accumulation indicates that cystic fibrosis impacts airway development. Our findings suggest that early airflow obstruction and air trapping in infants with cystic fibrosis might, in part, be caused by congenital airway abnormalities.

Influence of Applying Additional Forcing Fans for the Air Distribution in Ventilation Network

NASA Astrophysics Data System (ADS)

Szlązak, Nikodem; Obracaj, Dariusz; Korzec, Marek

2016-09-01

Mining progress in underground mines cause the ongoing movement of working areas. Consequently, it becomes necessary to adapt the ventilation network of a mine to direct airflow into newly-opened districts. For economic reasons, opening new fields is often achieved via underground workings. Length of primary intake and return routes increases and also increases the total resistance of a complex ventilation network. The development of a subsurface structure can make it necessary to change the air distribution in a ventilation network. Increasing airflow into newly-opened districts is necessary. In mines where extraction does not entail gas-related hazards, there is possibility of implementing a push-pull ventilation system in order to supplement airflows to newly developed mining fields. This is achieved by installing subsurface fan stations with forcing fans at the bottom of downcast shaft. In push-pull systems with multiple main fans, it is vital to select forcing fans with characteristic curves matching those of the existing exhaust fans to prevent undesirable mutual interaction. In complex ventilation networks it is necessary to calculate distribution of airflow (especially in networks with a large number of installed fans). In the article the influence of applying additional forcing fans for the air distribution in ventilation network for underground mine were considered. There are also analysed the extent of overpressure caused by the additional forcing fan in branches of the ventilation network (the operating range of additional forcing fan). Possibilities of increasing airflow rate in working areas were conducted.

Risk factors for persistent airflow limitation: Analysis of 306 patients with asthma.

PubMed

Wang, Lingcheng; Gao, Shuncui; Zhu, Wei; Su, Jun

2014-01-01

Objectives : To determine the risk factors associated with persistent airflow limitation in patients with asthma. Method s: This study was designed and carried out in the department of respiratory medicine, fourth People's Hospital of Jinan City, Shandong province, China between Jan 2012 and Dec 2012. Three hundred and six asthma patients participating in the study were divided into persistent airflow limitation group (PAFL) and no persistent airflow limitation group (NPAFL). The patients participated in pulmonary function tests and sputum induction examination. The clinical data including age, gender, onset age, disease course, smoking history, family history, regular corticosteroid inhalation, hospitalization history and presence of atopy were collected. Results : In 306 patients, 128 (40.5%) were included in PAFL group and 178(59.5%) in NPAFL group. Multivariate analysis demonstrated smoking (≥10 pack-years; OR, 7.1; 95% CI, 1.8 to 31.2), longer asthma duration (≥ 20years) (OR, 6.3; 95% CI, 1.7 to 28.5), absence of regular corticosteroid inhalation (OR, 3.5; 95% CI, 1.1 to 14.5) and neutrophil in induced sputum≥65% (OR, 1.8; 95% CI, 1.0 to 2.8) were independent risk factors for PAFL. Conclusions : Smoking, longer asthma duration and increased neutrophil in induced sputum are risk factors for PAFL, while regular corticosteroid inhalation is protective factor. Smoking cessation and regular corticosteroid inhalation may play an important role in preventing the occurrence of persistent airflow limitation group (PAFL).

Scoliosis associated with airflow obstruction due to endothoracic vertebral hump.

PubMed

Ito, Kenyu; Kawakami, Noriaki; Miyasaka, Kazuyoshi; Tsuji, Taichi; Ohara, Tetsuya; Nohara, Ayato

2012-12-01

A retrospective clinical study of scoliosis-associated airflow obstruction due to endothoracic vertebral hump. The purpose of this study was to evaluate and present anatomical features of patients with scoliosis who showed airflow obstruction caused by endothoracic vertebral hump. It is well known that severe scoliosis causes airflow restriction due to thoracic cage deformity. There have been few reports of clinical data and anatomical features on scoliosis associated with airflow obstruction due to endothoracic vertebral hump. The subjects were 6 patients. The diagnoses were idiopathic scoliosis in 3 patients, symptomatic scoliosis in 2 patients, and thoracogenic scoliosis in 1 patient. The radiological outcome, comorbidities, pre- and postoperative respiratory function, and surgical complication were analyzed. Four patients had preoperative atelectasis on the convex side of the lower lobe and improved after the operations. All patients showed main thoracic curves and their apex was located at T7-T9. All patients had lordoscoliosis except 1, who demonstrated kyphosing scoliosis. The correction rate was 78% (62.8%-83.5%). Preoperative thoracic lordosis within the range of -5° to -47° was postoperatively corrected to a substantially normal kyphosis within the range of 9° to 24°. The average vital capacity, percent VC improved from 0.72 L (0.33-1.17 L) to 1.21 L (0.82-1.71 L) and 45.5% (37.3%- 50.8%) to 63.7% (41.0%-88.6%) relatively. Spine Penetration Index improved from 23% (18%-35%) to 16% (13%-19%). Endothoracic hump ratio improved from 1.34 (0.98-1.93) to 1.12 (0.86-1.28). Each patient with symptomatic scoliosis and thoracogenic scoliosis required relatively long periods of respiration management. Patients having lordoscoliosis with an apex located between T7 and T9 may develop airflow obstruction due to an endothoracic vertebral hump. Correction of lordoscoliosis through anterior and posterior approaches successfully improved endothoracic hump ratio and atelectasis in all patients.

Usability Evaluation of a Flight-Deck Airflow Hazard Visualization System

NASA Technical Reports Server (NTRS)

Aragon, Cecilia R.

2004-01-01

Many aircraft accidents each year are caused by encounters with unseen airflow hazards near the ground, such as vortices, downdrafts, low level wind shear, microbursts, or turbulence from surrounding vegetation or structures near the landing site. These hazards can be dangerous even to airliners; there have been hundreds of fatalities in the United States in the last two decades attributable to airliner encounters with microbursts and low level wind shear alone. However, helicopters are especially vulnerable to airflow hazards because they often have to operate in confined spaces and under operationally stressful conditions (such as emergency search and rescue, military or shipboard operations). Providing helicopter pilots with an augmented-reality display visualizing local airflow hazards may be of significant benefit. However, the form such a visualization might take, and whether it does indeed provide a benefit, had not been studied before our experiment. We recruited experienced military and civilian helicopter pilots for a preliminary usability study to evaluate a prototype augmented-reality visualization system. The study had two goals: first, to assess the efficacy of presenting airflow data in flight; and second, to obtain expert feedback on sample presentations of hazard indicators to refine our design choices. The study addressed the optimal way to provide critical safety information to the pilot, what level of detail to provide, whether to display specific aerodynamic causes or potential effects only, and how to safely and effectively shift the locus of attention during a high-workload task. Three-dimensional visual cues, with varying shape, color, transparency, texture, depth cueing, and use of motion, depicting regions of hazardous airflow, were developed and presented to the pilots. The study results indicated that such a visualization system could be of significant value in improving safety during critical takeoff and landing operations, and also gave clear indications of the best design choices in producing the hazard visual cues.

ADVANTG Shielding Analysis for Closure Operations in an Open-Mode Repository

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bevill, Aaron M; Radulescu, Georgeta; Scaglione, John M

2013-01-01

en-mode repository concepts could require worker entry into access drifts after placement of fuel casks in order to perform activities related to backfill, plug emplacement, routine maintenance, or performance confirmation. An ideal emplacement-drift shielding configuration would minimize dose to workers while maximizing airflow through the emplacement drifts. This paper presents a preliminary investigation of the feasibility and effectiveness of radiation shielding concepts that could be employed to facilitate worker operations in an open-mode repository. The repository model for this study includes pressurized-water reactor fuel assemblies (60 GWd/MTU burnup, 40 year post-irradiation cooldown) in packages of 32 assemblies. The closest fuelmore » packages are 5 meters from dosimetry voxels in the access drift. The unshielded dose to workers in the access drift is 73.7 rem/hour. Prior work suggests that open-mode repository concepts similar to this one would require 15 m3/s of ventilation airflow. Shielding concepts considered here include partial concrete plugs, labyrinthine shields, and stainless steel photon attenuator grids. Maximum dose to workers in the access drift was estimated for each shielding concept using MCNP5 with variance reduction parameters generated by ADVANTG. Because airflow through the shielding is important for open-mode repositories, a semi-empirical estimate of the head loss due to each shielding configuration was also calculated. Airflow and shielding performance vary widely among the proposed shielding configurations. Although the partial plug configuration had the best airflow performance, it allowed dose rates 1500 greater than the specified target. Labyrinthine shielding concepts yield doses on the order of 1 mrem/hour with configurations that impose 3 to 11 J/kg head loss. Adding 1 cm lead lining to the airflow channels of labyrinthine designs further reduces the worker dose by 65% to 95%. Photon-attenuator concepts may reduce worker dose to as low as 29 mrem/hour with head loss on the order of 1.9 J/kg.« less

CPAP Devices for Emergency Prehospital Use: A Bench Study.

PubMed

Brusasco, Claudia; Corradi, Francesco; De Ferrari, Alessandra; Ball, Lorenzo; Kacmarek, Robert M; Pelosi, Paolo

2015-12-01

CPAP is frequently used in prehospital and emergency settings. An air-flow output minimum of 60 L/min and a constant positive pressure are 2 important features for a successful CPAP device. Unlike hospital CPAP devices, which require electricity, CPAP devices for ambulance use need only an oxygen source to function. The aim of the study was to evaluate and compare on a bench model the performance of 3 orofacial mask devices (Ventumask, EasyVent, and Boussignac CPAP system) and 2 helmets (Ventukit and EVE Coulisse) used to apply CPAP in the prehospital setting. A static test evaluated air-flow output, positive pressure applied, and FIO2 delivered by each device. A dynamic test assessed airway pressure stability during simulated ventilation. Efficiency of devices was compared based on oxygen flow needed to generate a minimum air flow of 60 L/min at each CPAP setting. The EasyVent and EVE Coulisse devices delivered significantly higher mean air-flow outputs compared with the Ventumask and Ventukit under all CPAP conditions tested. The Boussignac CPAP system never reached an air-flow output of 60 L/min. The EasyVent had significantly lower pressure excursion than the Ventumask at all CPAP levels, and the EVE Coulisse had lower pressure excursion than the Ventukit at 5, 15, and 20 cm H2O, whereas at 10 cm H2O, no significant difference was observed between the 2 devices. Estimated oxygen consumption was lower for the EasyVent and EVE Coulisse compared with the Ventumask and Ventukit. Air-flow output, pressure applied, FIO2 delivered, device oxygen consumption, and ability to maintain air flow at 60 L/min differed significantly among the CPAP devices tested. Only the EasyVent and EVE Coulisse achieved the required minimum level of air-flow output needed to ensure an effective therapy under all CPAP conditions. Copyright © 2015 by Daedalus Enterprises.

Lower Thoracic Spinal Cord Stimulation to Restore Cough in Patients with Spinal Cord Injury: Results of a National Institutes of Health-Sponsored Clinical Trial Part I: Methodology and Effectiveness of Expiratory Muscle Activation

PubMed Central

DiMarco, Anthony F.; Kowalski, Krzysztof E.; Geertman, Robert T.; Hromyak, Dana R.

2009-01-01

Objective Evaluation of the capacity of lower thoracic spinal cord stimulation (SCS) to activate the expiratory muscles and generate large airway pressures and high peak airflows characteristic of cough, in subjects with tetraplegia. Design Clinical trial. Setting In-patient hospital setting for electrode insertion; out-patient setting for measurement of respiratory pressures; home setting for application of SCS. Participants Subjects (N = 9; 8 men, 1 woman) with cervical spinal cord injury and weak cough. Intervention(s) A fully implantable electrical stimulation system was surgically placed in each subject. Partial hemilaminectomies were made to place single-disc electrodes in the epidural space at the T9, T11 and L1 spinal levels. A radiofrequency receiver was placed in the subcutaneous pocket over the anterior portion of the chest wall. Electrode wires were tunneled subcutaneously and connected to the receiver. Stimulation was applied by activating a small portable external stimulus controller box powered by a rechargeable battery to each electrode lead alone and in combination. Main Outcome Measure(s) Airway pressure and peak airflow generation achieved with SCS. Results Supramaximal SCS resulted in large airway pressures and high peak airflow rates during stimulation at each electrode lead. Maximum airway pressures and peak airflow rates were achieved with combined stimulation of any 2 leads. At total lung capacity, mean maximum airway pressure generation and peak airflow rates were 137 ± 30 cmH2O (mean ± SE) and 8.6 ± 1.8 (mean ± SE) L/s, respectively. Conclusions Lower thoracic SCS results in near maximum activation of the expiratory muscles and the generation of high positive airway pressures and peak airflow rates in the range of those observed with maximum cough efforts in normal individuals. PMID:19406289

Changes in Peak Airflow Measurement During Maximal Cough After Vocal Fold Augmentation in Patients With Glottic Insufficiency.

PubMed

Dion, Gregory R; Achlatis, Efstratios; Teng, Stephanie; Fang, Yixin; Persky, Michael; Branski, Ryan C; Amin, Milan R

2017-11-01

Compromised cough effectiveness is correlated with dysphagia and aspiration. Glottic insufficiency likely yields decreased cough strength and effectiveness. Although vocal fold augmentation favorably affects voice and likely improves cough strength, few data exist to support this hypothesis. To assess whether vocal fold augmentation improves peak airflow measurements during maximal-effort cough following augmentation. This case series study was conducted in a tertiary, academic laryngology clinic. Participants included 14 consecutive individuals with glottic insufficiency due to vocal fold paralysis, which was diagnosed via videostrobolaryngoscopy as a component of routine clinical examination. All participants who chose to proceed with augmentation were considered for the study whether office-based or operative augmentation was planned. Postaugmentation data were collected only at the first follow-up visit, which was targeted for 14 days after augmentation but varied on the basis of participant availability. Data were collected from June 5, 2014, to October 1, 2015. Data analysis took place between October 2, 2015, and March 3, 2017. Peak airflow during maximal volitional cough was quantified before and after vocal fold augmentation. Participants performed maximal coughs, and peak expiratory flow during the maximal cough was captured according to American Thoracic Society guidelines. Among the 14 participants (7 men and 7 women), the mean (SD) age was 62 (18) years. Three types of injectable material were used for vocal fold augmentation: carboxymethylcellulose in 5 patients, hyaluronic acid in 5, and calcium hydroxylapatite in 4. Following augmentation, cough strength increased in 11 participants and decreased cough strength was observed in 3. Peak airflow measurements during maximal cough varied from a decrease of 40 L/min to an increase of 150 L/min following augmentation. When preaugmentation and postaugmentation peak airflow measurements were compared, the median improvement was 50 L/min (95% CI, 10-75 L/min; P = .01). Immediate peak airflow measurements during cough collected within 30 minutes of augmentation varied when compared with measurements collected at follow-up (103-380 vs 160-390 L/min). Peak airflow during maximal cough may improve with vocal fold augmentation. Additional assessment and measurements are needed to further delineate which patients will benefit most regarding their cough from vocal fold augmentation.

Flow-induced resonance of screen-covered cavities

NASA Technical Reports Server (NTRS)

Soderman, Paul T.

1990-01-01

An experimental study of screen-covered cavities exposed to airflow tangent to the screen is described. The term screen refers to a thin metal plate perforated with a repetitive pattern of round holes. The purpose was to find the detailed aerodynamic and acoustic mechanisms responsible for screen-covered cavity resonance and to find ways to control the pressure oscillations. Results indicate that strong cavity acoustic resonances are created by screen orifices that shed vortices which couple resonance by choosing hole spacings such that shed vortices do not arrive at a downstream orifice in synchronization with cavity pressure oscillations. The proper hole pattern is effective at all airspeeds. It was also discovered that a reduction of orifice size tended to weaken the screen/cavity interaction regardless of hole pattern, probably because of viscous flow losses at the orifices. The screened cavities that resonated did so at much higher frequencies than the equivalent open cavity. The classical large eddy phenomenon occurs at the relatively small scale of the orifices (the excitation is typically of high frequency). The wind tunnel study was made at airspeeds from 0 to 100m/sec. The 457-mm-long by 1.09-m-high rectangular cavities had length-to-depth ratios greater than one, which is indicative of shallow cavities. The cavity screens were perforated in straight rows and columns with hole diameters ranging from 1.59 to 6.35 mm and with porosities from 2.6 to 19.6 percent.

The Impact of Urbanization on the Regional Aeolian Dynamics of an Arid Coastal Dunefield

NASA Astrophysics Data System (ADS)

Smith, Alexander; Jackson, Derek; Cooper, Andrew

2016-04-01

The anthropogenic impact on the geomorphology of many landscapes are inextricably connected but are often neglected due to the difficulty in making a direct link between the quasi natural and human processes that impact the environment. This research focuses on the Maspalomas dunefield, located on the southern coast of Gran Canaria, in the Canary Island Archipelago. The tourism industry in Maspalomas has led to intensive urbanization since the early 1960's over an elevated alluvial terrace that extends into the dunefield. Urbanization has had a substantial impact on both the regional airflow conditions and the geomorphological development of this transverse dune system. As a result airflow and sediment has been redirected in response to the large scale construction efforts. In situ data was collected during field campaigns using high resolution three-dimensional anemometry to identify the various modifications within the dunefield relative to incipient regional airflow conditions. The goal is to analyse the flow conditions near the urbanized terrace in relation to areas that are located away from the influence of the buildings and to verify numerical modelling results. Computational Fluid Dynamics (CFD) modelling is used in order to expand the areal extent of analysis by providing an understanding of relevant flow dynamics (e.g. flow velocity, directionality, turbulence, shear stresses, etc.) at the mesoscale. An integrative three dimensional model for CFD simulations was created to address the impact of both the urban area (i.e. hotels, commercial centers, and residential communities) as well as the dune terrain on regional flow conditions. Early modelling results show that there is significant flow modification around the urban terrace with streamline compression, acceleration, and deflection of flow on the windward side of the development. Consequently downwind of the terrace there is an area of highly turbulent flow conditions and well developed separation and deceleration zones as flow becomes modified by the building geometries. A historical analysis was then carried out to look at the direct link between regional airflow conditions pre and post urbanization. This is done by removing the modelled buildings and simulating flow conditions across the paleo alluvial terrace that is representative of the terrain prior to 1961. Modelling results show that there are largely unperturbed regional flow dynamics prior to urbanization with flow velocity, directionality, and turbulence remaining largely homogeneous at the mesoscale. Recent aerial LiDAR surveys show a distinct trend in the sediment dynamics (i.e. areas of accelerated and retarded dune migration) that correspond well to the modified flow conditions that have been simulated at the dunefield scale. This research begins to address the impact of societal pressures on natural systems by analysing the process-form relationship that has arisen from the coevolution of the Maspalomas dunefield.

Study of Airflow Out of the Mouth During Speech.

ERIC Educational Resources Information Center

Catford, J.C.; And Others

Airflow outside the mouth is diagnostic of articulatory activities in the vocal tract, both total volume-velocity and the distribution of particle velocities over the flow-front being useful for this purpose. A system for recording and displaying both these types of information is described. This consists of a matrix of l6 hot-wire anemometer flow…

Biomechanics of conidial dispersal in the toxic mold Stachybotrys chartarum

PubMed Central

Tucker, Kathryn; Stolze, Jessica L.; Kennedy, Aaron H.; Money, Nicholas P.

2007-01-01

Conidial dispersal in Stachybotrys chartarum in response to low-velocity airflow was studied using a microflow apparatus. The maximum rate of spore release occurred during the first 5 min of airflow, followed by a dramatic reduction in dispersal that left more than 99% of the conidia attached to their conidiophores. Micromanipulation of undisturbed colonies showed that micronewton (μN) forces were needed to dislodge spore clusters from their supporting conidiophores. Calculations show that airspeeds that normally prevail in the indoor environment disturb colonies with forces that are 1,000-fold lower, in the nanonewton (nN) range. Low-velocity airflow does not, therefore, cause sufficient disturbance to disperse a large proportion of the conidia of S. chartarum. PMID:17267247

Dislodgement and removal of dust-particles from a surface by a technique combining acoustic standing wave and airflow.

PubMed

Chen, Di; Wu, Junru

2010-01-01

It is known that there are many fine particles on the moon and Mars. Their existence may cause risk for the success of a long-term project for NASA, i.e., exploration and habitation of the moon and Mars. These dust-particles might cover the solar panels, making them fail to generate electricity, and they might also penetrate through seals on space suits, hatches, and vehicle wheels causing many incidents. The fine particles would be hazardous to human health if they were inhaled. Development of robust dust mitigation technology is urgently needed for the viable long-term exploration and habilitation of either the moon or Mars. A feasibility study to develop a dust removal technique, which may be used in space-stations or other enclosures for habitation, is reported. It is shown experimentally that the acoustic radiation force produced by a 13.8 kHz 128 dB sound-level standing wave between a 3 cm-aperture tweeter and a reflector separated by 9 cm is strong enough to overcome the van der Waals adhesive force between the dust-particles and the reflector-surface. Thus the majority of fine particles (>2 microm diameter) on a reflector-surface can be dislodged and removed by a technique combining acoustic levitation and airflow methods. The removal efficiency deteriorates for particles of less than 2 microm in size.

Determinants of spirometric abnormalities among silicotic patients in Hong Kong.

PubMed

Leung, Chi C; Chang, Kwok C; Law, Wing S; Yew, Wing W; Tam, Cheuk M; Chan, Chi K; Wong, Man Y

2005-09-01

Silicosis is the second commonest notified occupational disease in Hong Kong. To characterize the determinants of spirometric abnormalities in silicosis. The spirometric patterns of consecutive silicotic patients on confirmation by the Pneumoconiosis Medical Board from 1991 to 2002 were correlated with demographic characteristics, occupational history, smoking history, tuberculosis (TB) history and radiographic features by univariate and multiple regression analyses. Of 1576 silicotic patients included, 55.6% showed normal spirometry, 28.5% normal forced vital capacity (FVC>or=80% predicted) but reduced forced expiratory ratio (FER<70%), 7.6% reduced FVC but normal FER, and 8.4% reduced both FVC and FER. Age, ever-smoking, cigarette pack-years, industry, job type, history of TB, size of lung nodules and progressive massive fibrosis (PMF) were all significantly associated with airflow limitation on univariate analysis (all P<0.05), while sex and profusion of nodules were not. Only age, cigarette pack-years, history of TB, size of lung nodules and PMF remained as significant independent predictors of airflow obstruction in multiple logistic regression analysis. After controlling for airflow obstruction, only shorter exposure duration, history of TB and profusion of nodules were significant independent predictors of reduced FVC. As well as age, history of TB, cigarette pack-years, PMF and nodule size contributed comparable effects to airflow obstruction in multiple linear regression analyses, while profusion of nodules was the strongest factor for reduced vital capacity. In an occupational compensation setting, disease indices and history of tuberculosis are independent predictors of both airflow obstruction and reduced vital capacity for silicotic patients.

Characterization of deposition from nasal spray devices using a computational fluid dynamics model of the human nasal passages.

PubMed

Kimbell, Julia S; Segal, Rebecca A; Asgharian, Bahman; Wong, Brian A; Schroeter, Jeffry D; Southall, Jeremy P; Dickens, Colin J; Brace, Geoff; Miller, Frederick J

2007-01-01

Many studies suggest limited effectiveness of spray devices for nasal drug delivery due primarily to high deposition and clearance at the front of the nose. Here, nasal spray behavior was studied using experimental measurements and a computational fluid dynamics model of the human nasal passages constructed from magnetic resonance imaging scans of a healthy adult male. Eighteen commercially available nasal sprays were analyzed for spray characteristics using laser diffraction, high-speed video, and high-speed spark photography. Steadystate, inspiratory airflow (15 L/min) and particle transport were simulated under measured spray conditions. Simulated deposition efficiency and spray behavior were consistent with previous experimental studies, two of which used nasal replica molds based on this nasal geometry. Deposition fractions (numbers of deposited particles divided by the number released) of 20- and 50-microm particles exceeded 90% in the anterior part of the nose for most simulated conditions. Predicted particle penetration past the nasal valve improved when (1) the smaller of two particle sizes or the lower of two spray velocities was used, (2) the simulated nozzle was positioned 1.0 rather than 0.5 or 1.5 cm into the nostril, and (3) inspiratory airflow was present rather than absent. Simulations also predicted that delaying the appearance of normal inspiratory airflow more than 1 sec after the release of particles produced results equivalent to cases in which no inspiratory airflow was present. These predictions contribute to more effective design of drug delivery devices through a better understanding of the effects of nasal airflow and spray characteristics on particle transport in the nose.

Ethmoidectomy combined with superior meatus enlargement increases olfactory airflow

PubMed Central

Kondo, Kenji; Nomura, Tsutomu; Yamasoba, Tatsuya

2017-01-01

Objectives The relationship between a particular surgical technique in endoscopic sinus surgery (ESS) and airflow changes in the post‐operative olfactory region has not been assessed. The present study aimed to compare olfactory airflow after ESS between conventional ethmoidectomy and ethmoidectomy with superior meatus enlargement, using virtual ESS and computational fluid dynamics (CFD) analysis. Study Design Prospective computational study. Materials and Methods Nasal computed tomography images of four adult subjects were used to generate models of the nasal airway. The original preoperative model was digitally edited as virtual ESS by performing uncinectomy, ethmoidectomy, antrostomy, and frontal sinusotomy. The following two post‐operative models were prepared: conventional ethmoidectomy with normal superior meatus (ESS model) and ethmoidectomy with superior meatus enlargement (ESS‐SM model). The calculated three‐dimensional nasal geometries were confirmed using virtual endoscopy to ensure that they corresponded to the post‐operative anatomy observed in the clinical setting. Steady‐state, laminar, inspiratory airflow was simulated, and the velocity, streamline, and mass flow rate in the olfactory region were compared among the preoperative and two postoperative models. Results The mean velocity in the olfactory region, number of streamlines bound to the olfactory region, and mass flow rate were higher in the ESS‐SM model than in the other models. Conclusion We successfully used an innovative approach involving virtual ESS, virtual endoscopy, and CFD to assess postoperative outcomes after ESS. It is hypothesized that the increased airflow to the olfactory fossa achieved with ESS‐SM may lead to improved olfactory function; however, further studies are required. Level of Evidence NA. PMID:28894833

Using color intensity projections to visualize air flow in operating theaters with the goal of reducing infections

NASA Astrophysics Data System (ADS)

Cover, Keith S.; van Asperen, Niek; de Jong, Joost; Verdaasdonk, Rudolf M.

2013-03-01

Infection following neurosurgery is all too common. One possible source of infection is the transportation of dust and other contaminates into the open wound by airflow within the operating theatre. While many modern operating theatres have a filtered, uniform and gentle flow of air cascading down over the operating table from a large area fan in the ceiling, many obstacles might introduce turbulence into the laminar flow including lights, equipment and personal. Schlieren imaging - which is sensitive to small disturbances in the laminar flow such as breathing and turbulence caused by air warmed by a hand at body temperature - was used to image the air flow due to activities in an operating theatre. Color intensity projections (CIPs) were employed to reduce the workload of analyzing the large amount of video data. CIPs - which has been applied to images in angiography, 4D CT, nuclear medicine and astronomy - summarizes the changes over many gray scale images in a single color image in a way which most interpreters find intuitive. CIPs uses the hue, saturation and brightness of the color image to encode the summary. Imaging in an operating theatre showed substantial disruptions to the airflow due to equipment such as the lighting. When these disruptions are combined with such minor factors as heat from the hand, reversal of the preferred airflow patterns can occur. These reversals of preferred airflow patterns have the potential to transport contaminates into the open wound. Further study is required to understand both the frequency of the reversed airflow patterns and the impact they may have on infection rates.

Comparison between mixed and laminar airflow systems in operating rooms and the influence of human factors: experiences from a Swedish orthopedic center.

PubMed

Erichsen Andersson, Annette; Petzold, Max; Bergh, Ingrid; Karlsson, Jón; Eriksson, Bengt I; Nilsson, Kerstin

2014-06-01

The importance of laminar airflow systems in operating rooms as protection from surgical site infections has been questioned. The aim of our study was to explore the differences in air contamination rates between displacement ventilation and laminar airflow systems during planned and acute orthopedic implant surgery. A second aim was to compare the influence of the number of people present, the reasons for traffic flow, and the door-opening rates between the 2 systems. Active air sampling and observations were made during 63 orthopedic implant operations. The laminar airflow system resulted in a reduction of 89% in colony forming units in comparison with the displacement system (P < .001). The air samples taken in the preparation rooms showed high levels of bacterial growth (≈ 40 CFU/m(3)). Our study shows that laminar airflow-ventilated operating rooms offer high-quality air during surgery, with very low levels of colony forming units close to the surgical wound. The continuous maintenance of laminar air flow and other technical systems are crucial, because minor failures in complex systems like those in operating rooms can result in a detrimental effect on air quality and jeopardize the safety of patients. The technical ventilation solutions are important, but they do not guarantee clean air, because many other factors, such as the organization of the work and staff behavior, influence air cleanliness. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Phonatory aerodynamics in connected speech.

PubMed

Gartner-Schmidt, Jackie L; Hirai, Ryoji; Dastolfo, Christina; Rosen, Clark A; Yu, Lan; Gillespie, Amanda I

2015-12-01

1) Present phonatory aerodynamic data for healthy controls (HCs) in connected speech; 2) contrast these findings between HCs and patients with nontreated unilateral vocal fold paralysis (UVFP); 3) present pre- and post-vocal fold augmentation outcomes for patients with UVFP; 4) contrast data from patients with post-operative laryngeal augmentation to HCs. Retrospective, single-blinded. For phase I, 20 HC participants were recruited. For phase II, 20 patients with UVFP were age- and gender-matched to the 20 HC participants used in phase I. For phase III, 20 patients with UVFP represented a pre- and posttreatment cohort. For phase IV, 20 of the HC participants from phase I and 20 of the postoperative UVFP patients from phase III were used for direct comparison. Aerodynamic measures captured from a sample of the Rainbow Passage included: number of breaths, mean phonatory airflow rate, total duration of passage, inspiratory airflow duration, and expiratory airflow duration. The VHI-10 was also obtained pre- and postoperative laryngeal augmentation. All phonatory aerodynamic measures were significantly increased in patients with preoperative UVFP than the HC group. Patients with laryngeal augmentation took significantly less breaths, had less mean phonatory airflow rate during voicing, and had shorter inspiratory airflow duration than the preoperative UVFP group. None of the postoperative measures returned to HC values. Significant improvement in the Voice Handicap Index-10 scores postlaryngeal augmentation was also found. Methodology described in this study improves upon existing aerodynamic voice assessment by capturing characteristics germane to UVFP patient complaints and measuring change before and after laryngeal augmentation in connected speech. 4. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

Nonstimulated rabbit phonation model: Cricothyroid approximation.

PubMed

Novaleski, Carolyn K; Kojima, Tsuyoshi; Chang, Siyuan; Luo, Haoxiang; Valenzuela, Carla V; Rousseau, Bernard

2016-07-01

To describe a nonstimulated in vivo rabbit phonation model using an Isshiki type IV thyroplasty and uninterrupted humidified glottal airflow to produce sustained audible phonation. Prospective animal study. Six New Zealand white breeder rabbits underwent a surgical procedure involving an Isshiki type IV thyroplasty and continuous airflow delivered to the glottis. Phonatory parameters were examined using high-speed laryngeal imaging and acoustic and aerodynamic analysis. Following the procedure, airflow was discontinued, and sutures remained in place to maintain the phonatory glottal configuration for microimaging using a 9.4 Tesla imaging system. High-speed laryngeal imaging revealed sustained vocal fold oscillation throughout the experimental procedure. Analysis of acoustic signals revealed a mean vocal intensity of 61 dB and fundamental frequency of 590 Hz. Aerodynamic analysis revealed a mean airflow rate of 85.91 mL/s and subglottal pressure of 9 cm H2 O. Following the procedure, microimaging revealed that the in vivo phonatory glottal configuration was maintained, providing consistency between the experimental and postexperimental laryngeal geometry. The latter provides a significant milestone that is necessary for geometric reconstruction and to allow for validation of computational simulations against the in vivo rabbit preparation. We demonstrate a nonstimulated in vivo phonation preparation using an Isshiki type IV thyroplasty and continuous humidified glottal airflow in a rabbit animal model. This preparation elicits sustained vocal fold vibration and phonatory measures that are consistent with our laboratory's prior work using direct neuromuscular stimulation for evoked phonation. N/A. Laryngoscope, 126:1589-1594, 2016. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Building America Case Study: High-Velocity Small-Diameter Duct System, Pittsburgh, Pennsylvania

DOE Office of Scientific and Technical Information (OSTI.GOV)

A. Poerschke

This study tests the performance of a variable airflow small-diameter duct heating, ventilation, and air conditioning (HVAC) system in a new construction unoccupied low-load test house in Pittsburgh, Pennsylvania. The duct system was installed entirely in conditioned space and was operated from the winter through summer seasons. Measurements were collected on the in-room temperatures and energy consumed by the air handler and heat pump unit. Operation modes with three different volumes of airflow were compared to determine the ideal airflow scenario that maximizes room-to-room thermal uniformity while minimizing fan energy consumption. Black felt infrared imagery was used as a measuremore » of diffuser throw and in-room air mixing. Measured results indicate the small-diameter, high velocity airflow system can provide comfort under some conditions. Solar heat gains resulted in southern rooms drifting beyond acceptable temperature limits. Insufficient airflow to some bedrooms also resulted in periods of potential discomfort. Homebuilders or HVAC contractors can use these results to assess whether this space conditioning strategy is an attractive alternative to a traditional duct system. The team performed a cost analysis of two duct system configurations: (1) a conventional diameter and velocity duct system, and (2) the small-diameter duct system. This work applies to both new and retrofit homes that have achieved a low heating and cooling density either by energy conservation or by operation in a mild climate with few heating or cooling degree days. Guidance is provided on cost trade-offs between the conventional duct system and the small-diameter duct system.« less

Low speed tests of a fixed geometry inlet for a tilt nacelle V/STOL airplane

NASA Technical Reports Server (NTRS)

Syberg, J.; Koncsek, J. L.

1977-01-01

Test data were obtained with a 1/4 scale cold flow model of the inlet at freestream velocities from 0 to 77 m/s (150 knots) and angles of attack from 45 deg to 120 deg. A large scale model was tested with a high bypass ratio turbofan in the NASA/ARC wind tunnel. A fixed geometry inlet is a viable concept for a tilt nacelle V/STOL application. Comparison of data obtained with the two models indicates that flow separation at high angles of attack and low airflow rates is strongly sensitive to Reynolds number and that the large scale model has a significantly improved range of separation-free operation.

Computational Fluid Dynamics Uncertainty Analysis for Payload Fairing Spacecraft Environmental Control Systems

NASA Technical Reports Server (NTRS)

Groves, Curtis; Ilie, Marcel; Schallhorn, Paul

2014-01-01

Spacecraft components may be damaged due to airflow produced by Environmental Control Systems (ECS). There are uncertainties and errors associated with using Computational Fluid Dynamics (CFD) to predict the flow field around a spacecraft from the ECS System. This paper describes an approach to estimate the uncertainty in using CFD to predict the airflow speeds around an encapsulated spacecraft.

42 CFR 84.153 - Airflow resistance test, Type A and Type AE supplied-air respirators; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 89 300 91 4.0 102 (c) The exhalation resistance shall not exceed 25 mm. (1 inch) of water-column... 42 Public Health 1 2010-10-01 2010-10-01 false Airflow resistance test, Type A and Type AE supplied-air respirators; minimum requirements. 84.153 Section 84.153 Public Health PUBLIC HEALTH SERVICE...

77 FR 5990 - Special Conditions: Learjet Inc., Model LJ-200-1A10 Airplane, Pilot-Compartment View Through...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-07

... airflow to maintain a clear-vision area. The heavy rain and high speed conditions specified in the current... to maintain a sufficiently clear area of the windshield in low-speed flight or during surface... airflow disturbance or separation on the windshield could cause failure to maintain a clear-vision area on...

Performance assessment of U.S. residential cooking exhaust hoods.

PubMed

Delp, William W; Singer, Brett C

2012-06-05

This study assessed the performance of seven new residential cooking exhaust hoods representing common U.S. designs. Laboratory tests were conducted to determine fan curves relating airflow to duct static pressure, sound levels, and exhaust gas capture efficiency for front and back cooktop burners and the oven. Airflow rate sensitivity to duct flow resistance was higher for axial fan devices than for centrifugal fan devices. Pollutant capture efficiency (CE) ranged from <15% to >98%, varying across hoods and with airflow and burner position for each hood. CE was higher for back burners relative to front burners, presumably because most hoods covered only part of the front burners. Open hoods had higher CE than those with grease screen and metal-covered bottoms. The device with the highest CE--exceeding 80% for oven and front burners--had a large, open hood that covered most of the front burners. The airflow rate for this hood surpassed the industry-recommended level of 118 L·s(-1) (250 cfm) and produced sound levels too high for normal conversation. For hoods meeting the sound and fan efficacy criteria for Energy Star, CE was <30% for front and oven burners.

Toward smart Nebulization: Engineering acoustic airflow to penetrate maxillary sinuses in chronic rhinosinusitis.

PubMed

Moghadam, Shima Jowhari; Navarro, Laurent; Leclerc, Lara; Hodin, Sophie; Pourchez, Jérémie

2018-07-30

Treating chronic rhinosinusitis (CRS) by nebulization requires an airflow capable to deliver medication to deep target sites beyond the nasal valve. Fixed frequency acoustic airflow technology is currently available, mainly as post-surgical therapy, but still have not been able to realize the full potential of direct nose to paranasal sinuses delivery. Reported herein are the application of frequency sweep acoustic airflow and the optimization of its frequency range, sweep cycle duration and intensity. The resonant frequencies of the model's maxillary sinuses can be estimated using the Helmholtz resonator theory. Results indicated a resonant frequency of 479 Hz for the right maxillary sinus and one of 849 Hz for the left maxillary sinus. The highest intrasinus deposition within the experiments are from sweep cycle duration of 1 s, intensity of 80 dB, and frequency range of 100-850 Hz. The optimal range of frequency determined from experiments is in good agreement with the corresponding frequency range obtained from the Helmholtz resonator theory. Results reveal a significantly enhanced maxillary sinus drug deposition. This technique affords the potential of treating CRS. Copyright © 2018 Elsevier B.V. All rights reserved.

Hair sensor using a photoelectronic principle for sensing airflow and its direction

NASA Astrophysics Data System (ADS)

Huang, Kuang-Yuh; Huang, Chien-Tai

2011-01-01

Many organisms have diverse hair cells to instantaneously perceive the change of surroundings so that they can keep away from threats. These organs can precisely detect the tiny variations of airflow, water flow, sound, or pressure, and also resolve their affecting directions. Through this brilliant inspiration by the insects' cilia, we decided to design and develop a hair sensor for detecting two-dimensional airflow and pressure waves by using photoelectronic principles. The hair sensor inherently consists of an artificial cilium supported by an elastic membrane. A light-emitting diode and a quadrant photodiode are used as the photoelectronic sensor. The airflow or pressure wave directly stimulates the cilium to sway, and this motion contributes to let the projected light beam shift over the quadrant photodiode, whose four photodiodes produce then corresponding output signals. Because of dynamic and high-sensitive properties of the photoelectronic sensor, the hair sensor we developed possesses a high measurement resolution to be able to detect very tiny stimulation and its affecting direction. According to its multifaceted characteristics and simple structure, the hair sensor can be applied in numerous potential application fields, such as intrusion alarm system, noise detection system, as well as a tactile sensor.

Measuring Device for Air Speed in Macroporous Media and Its Application Inside Apple Storage Bins.

PubMed

Geyer, Martin; Praeger, Ulrike; Truppel, Ingo; Scaar, Holger; Neuwald, Daniel A; Jedermann, Reiner; Gottschalk, Klaus

2018-02-13

In cold storage facilities of fruit and vegetables, airflow is necessary for heat removal. The design of storage facilities influences the air speed in the surrounding of the product. Therefore, knowledge about airflow next to the product is important to plan the layout of cold stores adapted to the requirements of the products. A new sensing device (ASL, Air speed logger) is developed for omnidirectional measurement of air speed between fruit or vegetables inside storage bins or in bulk. It consists of four interconnected plastic spheres with 80 mm diameter each, adapted to the size of apple fruit. In the free space between the spheres, silicon diodes are fixed for the airflow measurement based on a calorimetric principle. Battery and data logger are mounted inside the spheres. The device is calibrated in a wind tunnel in a measuring range of 0-1.3 m/s. Air speed measurements in fruit bulks on laboratory scale and in an industrial fruit store show air speeds in gaps between fruit with high stability at different airflow levels. Several devices can be placed between stored products for determination of the air speed distribution inside bulks or bin stacks in a storage room.

Role of upper airway in ventilatory control in awake and sleeping dogs.

PubMed

Stradling, J R; England, S J; Harding, R; Kozar, L F; Andrey, S; Phillipson, E A

1987-03-01

We examined the role of the upper airway in the regulation of the pattern of breathing in six adult dogs during wakefulness and sleep. The dogs breathed through a fenestrated endotracheal tube inserted through a tracheostomy. The tube was modified to allow airflow to be directed either through the nose or through the tracheostomy. When airflow was diverted from nose to tracheostomy there was an abrupt increase in the rate of expiratory airflow, resulting in prolongation of the end-expiratory pause but no change in overall expiratory duration or respiratory frequency. Furthermore, electromyogram recordings from implanted diaphragmatic and laryngeal muscle electrodes did not show any changes that could be interpreted as an attempt to delay expiratory airflow or increase end-expiratory lung volume. The effects of switching from nose to tracheostomy breathing could be reversed by adding a resistance to the endotracheal tube so as to approximate upper airway resistance. The findings indicate that under normal conditions in the adult dog upper airway receptors play little role in regulation of respiratory pattern and that the upper airway exerts little influence on the maintenance of end-expiratory lung volume.

Calculation of air movement in ice caves by using the CalcFlow method

NASA Astrophysics Data System (ADS)

Meyer, Christiane; Pflitsch, Andreas; Maggi, Valter

2017-04-01

We present a method to determine the air flow regime within ice caves by temperature loggers. Technical capabilities of conducting airflow measurements are restricted by the availability of energy at the ice cave study sites throughout the year. Though the knowledge of the airflow regime is a prerequisite for the understanding of the cave climate. By cross-correlating different time series of air temperature measurements inside a cave, we define the travel time of the air between the loggers, which corresponds to the time shift of best correlation, and use this result to derive the airflow speed. Then we estimate the temperature biases and scale factors for the temperature variations observed by the different loggers by a least squares adjustment. As quality control for bias and scale we use the formal errors of the estimation process. For the calculated airflow speed quality criteria are developed by use of a simulation study. Furthermore we will apply the method to temperature measurements in the static ice cave Schellenberger Eishöhle (Germany). In the end we show how the method can be used as an advanced filter for the separation of different signal contents of the temperature measurements.

The impact of intraglottal vortices on vocal fold dynamics

NASA Astrophysics Data System (ADS)

Erath, Byron; Pirnia, Alireza; Peterson, Sean

2016-11-01

During voiced speech a critical pressure is produced in the lungs that separates the vocal folds and creates a passage (the glottis) for airflow. As air passes through the vocal folds the resulting aerodynamic loading, coupled with the tissue properties of the vocal folds, produces self-sustained oscillations. Throughout each cycle a complex flow field develops, characterized by a plethora of viscous flow phenomena. Air passing through the glottis creates a jet, with periodically-shed vortices developing due to flow separation and the Kelvin-Helmholtz instability in the shear layer. These vortices have been hypothesized to be a crucial mechanism for producing vocal fold vibrations. In this study the effect of vortices on the vocal fold dynamics is investigated experimentally by passing a vortex ring over a flexible beam with the same non-dimensional mechanical properties as the vocal folds. Synchronized particle image velocimetry data are acquired in tandem with the beam dynamics. The resulting impact of the vortex ring loading on vocal fold dynamics is discussed in detail. This work was supported by the National Science Foundation Grant CBET #1511761.

The response of stationary planetary waves to tropospheric forcing

NASA Technical Reports Server (NTRS)

Alpert, J. C.; Geller, M. A.; Avery, S. K.

1983-01-01

The lower boundary forcing of airflow over topography, and the internal forcing that results from the geographical distribution of diabatic heating, are studied in light of a steady state, linear, quasi-geostrophic model of stationary waves on a sphere. The lower boundary vertical motions forced by airflow over topography depend on whether the horizontal deflection of airflow around topographic features is taken into account, the level of the wind profile at which flow over topography is assumed to take place, and the topographic data set that was used in the forcing formulation. The lower boundary forcing is taken to be given by the observed stationary planetary wave in lower boundary geopotential height, and the internal forcing is computed using the planetary wave propagation equation on the observed wave structure.

Technology development activities for housing research animals on Space Station Freedom

NASA Technical Reports Server (NTRS)

Jenner, Jeffrey W.; Garin, Vladimir M.; Nguyen, Frank D.

1991-01-01

The development and design of animal facilities are described in terms of the technological needs for NASA's Biological Flight Research Laboratory. Animal habitats are presented with illustrations which encompass waste-collection techniques for microgravity conditions that reduce the need for crew participation. The technology is intended to be highly compatible with animal morphology, and airflow is employed as the primary mechanism of waste control. The airflow can be utilized in the form of localized high-speed directed flow that simultaneously provides a clean animal habitat and low airflow rates. The design of an animal-habitat testbed is presented which capitalizes on contamination-control mechanisms and suitable materials for microgravity conditions. The developments in materials and technologies represent significant contributions for the design of the centrifuge facilities for the Space Station Freedom.

Numerical calculation of the influence of axial position on the performance of stepped labyrinth seals

NASA Astrophysics Data System (ADS)

Wang, Dianhai; Shi, Chengying; Cai, Xinghui

2018-05-01

In order to analyze the influence of the change of axial position on the performance of labyrinth gear, the Fluent is used to simulate the airflow in the labyrinth in this paper. The leakage coefficient and heat transfer coefficient of the sealing teeth under different axial positions are obtained. The comparisons of results shows that the change of the axial position of the stepped labyrinth seals and the bushing has little effect on the airflow inside the cavity, and the change of axial position has little influence on the leakage coefficient of labyrinth seal; The change in the axial position of the stepped labyrinth seals and the bushing does not lead to a significant effect on the heat transfer characteristics of the airflow and the cavity channel.

Response of Metal Core Piezoelectric Fibers to Unsteady Airflows

NASA Astrophysics Data System (ADS)

Qiu, J. H.; Ji, H. L.; Zhu, K. J.; Park, M. J.

In the previous study, possible applications of metal core piezoelectric fibers with a diameter of 200 to 250 µm as bionic airflow sensors mimicking the flow sensitive receptor hairs of crickets have been proposed. This study aims to investigate the dynamic responses of the metal core piezoelectric fibers to unsteady airflow. The metal core piezoelectric fiber is half coated on the outer surface and is used in the bending mode. Wind tunnel tests were carried out and the output voltage of the fiber under the excitation of the unsteady aerodynamic force during flow acceleration and deceleration was measured when the wind tunnel was suddenly closed or opened by a shutter. The relationship between the maximum voltage and the steady-state velocity and that between the voltage and the acceleration of flow were also obtained.

Fabrication of highly oriented nanoporous fibers via airflow bubble-spinning

NASA Astrophysics Data System (ADS)

Liu, Fujuan; Li, Shaokai; Fang, Yue; Zheng, Fangfang; Li, Junhua; He, Jihuan

2017-11-01

Highly oriented Poly(lactic acid) (PLA) nanofibers with nanoporous structures has been successfully fabricated via airflow bubble-spinning without electrostatic hazard. In this work, the volatile solvent was necessary for preparing the nanoporous fiber, which was attributed to the competition between phase separation and solvent evaporation. The interconnected porous structures were affected by the processing variables of solution concentration, airflow temperature, collecting distance and relative humidity (RH). Besides, the rheological properties of solutions were studied and the highly oriented PLA nanofibers with nanoporous structure were also completely characterized using scanning electron microscope (SEM). This study provided a novel technique that successfully gets rid of the potential safety hazards caused by unexpected static to prepare highly oriented nanoporous fibers, which would demonstrate an impressive prospect for the fields of adsorption and filtration.

Impact of surface disinfection and sterile draping of furniture on room air quality in a cardiac procedure room with a ventilation and air-conditioning system (extrusion airflow, cleanroom class 1b (DIN 1946-4)).

PubMed

Below, Harald; Ryll, Sylvia; Empen, Klaus; Dornquast, Tina; Felix, Stefan; Rosenau, Heike; Kramer, Sebastian; Kramer, Axel

2010-09-21

In a cardiac procedure room, ventilated by a ventilation and air-conditioning system with turbulent mixed airflow, a protection zone in the operating area could be defined through visualization of airflows. Within this protection zone, no turbulence was detectable in the room air.Under the given conditions, disinfection of all surfaces including all furniture and equipment after the last operation and subsequent draping of furniture and all equipment that could not be removed from the room with sterile surgical drapes improved the indoor room air quality from cleanroom class C to cleanroom class B. This also allows procedures with elevated requirements to be performed in room class 1b.

Innovative method and equipment for personalized ventilation.

PubMed

Kalmár, F

2015-06-01

At the University of Debrecen, a new method and equipment for personalized ventilation has been developed. This equipment makes it possible to change the airflow direction during operation with a time frequency chosen by the user. The developed office desk with integrated air ducts and control system permits ventilation with 100% outdoor air, 100% recirculated air, or a mix of outdoor and recirculated air in a relative proportion set by the user. It was shown that better comfort can be assured in hot environments if the fresh airflow direction is variable. Analyzing the time step of airflow direction changing, it was found that women prefer smaller time steps and their votes related to thermal comfort sensation are higher than men's votes. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Pressure activated stability-bypass-control valves to increase the stable airflow range of a Mach 2.5 inlet with 40 percent internal contraction

NASA Technical Reports Server (NTRS)

Mitchell, G. A.; Sanders, B. W.

1974-01-01

The throat of a Mach 2.5 inlet with a coldpipe termination was fitted with a stability-bypass system. The inlet stable airflow range provided by various stability-bypass entrance configurations in alternate combination with several stability-bypass exit controls was determined for both steady-state conditions and internal transient pulses. Transient results were also obtained for the inlet with a choke point at the diffuser exit. Instart angles of attack were determined for the various stability-bypass entrance configurations. The response of the inlet-coldpipe system to internal and external oscillating disturbances was determined. Poppet valves at the stability-bypass exit provided an inlet stable airflow range of 28 percent or greater at all static and transient conditions.

Improving Aviation Safety with information Visualization: A Flight Simulation Study

NASA Technical Reports Server (NTRS)

Aragon, Cecilia R.; Hearst, Marti

2005-01-01

Many aircraft accidents each year are caused by encounters with invisible airflow hazards. Recent advances in aviation sensor technology offer the potential for aircraft-based sensors that can gather large amounts of airflow velocity data in real-time. With this influx of data comes the need to study how best to present it to the pilot - a cognitively overloaded user focused on a primary task other than that of information visualization. In this paper, we present the results of a usability study of an airflow hazard visualization system that significantly reduced the crash rate among experienced helicopter pilots flying a high fidelity, aerodynamically realistic fixed-base rotorcraft flight simulator into hazardous conditions. We focus on one particular aviation application, but the results may be relevant to user interfaces in other operationally stressful environments.

Evaluation of wind regimes and their impact on vertical mixing and coupling in a moderately dense forest

NASA Astrophysics Data System (ADS)

Wunder, Tobias; Ehrnsperger, Laura; Thomas, Christoph

2017-04-01

In the last decades much attention has been devoted to improving our understanding of organized motions in plant canopies. Particularly the impact of coherent structures on turbulent flows and vertical mixing in near-neutral conditions has been the focus of many experimental and modeling studies. Despite this progress, the weak-wind subcanopy airflow in concert with stable or weak-wind above-canopy conditions remains poorly understood. In these conditions, evidence is mounting that larger-scale motions, so called sub-meso motions which occupy time scales from minutes to hours and spatial scales from tens of meters to kilometers, dominate transport and turbulent mixing particularly in the subcanopy, because of generally weaker background flow as a result of the enhanced friction due to the plant material. We collected observations from a network of fast-response sensor across the vertical and horizontal dimensions during the INTRAMIX experiment at the Fluxnet site Waldstein/ Weidenbrunnen (DE-Bay) in a moderately dense Norway spruce (Picea Abies) forest over a period of ten weeks. Its main goal was to investigate the role of the submeso-structures on the turbulent wind field and the mixing mechanisms including coherent structures. In a first step, coupling regimes differentiating between weak and strong flows and day- and nighttime-conditions are determined. Subsequently, each of the regimes is analyzed for its dominant flow dynamics identified by wavelet analysis. It is hypothesized that strong vertical wind directional shear does not necessarily indicate a decoupling of vertical layers, but on the contrary may create situations of significant coupling of the sub-canopy with the canopy layers above. Moreover, rapid changes of wind direction or even reversals may generate substantial turbulence and induce intermittent coupling on a variety of time scales. The overarching goal is to improve diagnostics for vertical mixing in plant canopies incorporating turbulence and submeso-motions and to develop a classification of flow modes capable of representing the main driving mechanisms of mixing in forest canopies.

Numerical simulations of island-scale airflow over Maui and the Maui vortex under summer trade wind conditions

Treesearch

DaNa L. Carlis; Yi-Leng Chen; Vernon R. Morris

2010-01-01

The fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) coupled with the Noah land surface model (LSM) is employed to simulate island-scale airflow and circulations over Maui County, Hawaii, under summer trade wind conditions, during July–August 2005. The model forecasts are validated by surface observations with good agreement.

A COMPARISON OF AIRFLOW PATTERNS FROM THE QUIC MODEL AND AN ATMOSPHERIC WIND TUNNEL FOR A TWO-DIMENSIONAL BUILDING ARRAY AND A MULTI-CITY BLOCK REGION NEAR THE WORLD TRADE CENTER SITE

EPA Science Inventory

Dispersion of pollutants in densely populated urban areas is a research area of clear importance. Currently, few numerical tools exist capable of describing airflow and dispersion patterns in these complex regions in a time efficient manner. (QUIC), Quick Urban & Industrial C...

Comparative investigations of anatomy and physiology in mammalian noses (Homo sapiens--Artiodactyla).

PubMed

Grützenmacher, S; Robinson, D M; Sevecke, J; Mlynski, G; Beule, A G

2011-03-01

Knowledge of airflow in animal noses is sparse. Such knowledge could be important for selection of animal models used in environmental studies. From the phylogenetic and ontogenetic point of view, a comparison between the animal and human nose is interesting. Nose models of 5 even-toed ungulate species (he-goat, sheep, cow, roebuck, wild boar) and two humans (new born infant and adult) were examined. Anatomical and physiological features of the nasal cavities of all species were compared. All models were rinsed with water and the flow was visualized for observation. Geometric and rhinoresistometric measurements were then performed. Even-toed ungulates have two turbinates directly in the main part of the nasal airflow (respiratory turbinates) and a different number of turbinates in a so-called dead space of the nasal airflow above the nasopharyngeal duct (ethmoidal turbinates). The latter correspond with the upper and middle turbinate in analogy to the human nose. Respiratory turbinates of even-toed ungulates insert immediately behind the external nasal ostium. Thus, the whole nasal cavity acts as a functional area with the exception of a small area acting as dead space only detectable in ruminants, possibly indicating a small evolutionary progress from suinae to bovidae. The shape of the animal nasal cavity is stretched and flat. The airflow runs nearly completely turbulent through the nose. The nasal cavity in the adult human is relatively short and high. The area between the external nasal ostium and the head of the inferior turbinate is called inflow area. It distributes the airflow over the whole nasal cross section and generates a turbulent flow. So the airflow is prepared to contact the mucosa in the functional area (turbinate area). The morphology of the inflow area is approximately formed by the shape of the external nose. The nasal cavity of a newborn child is also stretched and flat and more similar to the nasal shape of the investigated animals. The inflow area in the newborn nose is not yet developed and corresponds with the growing external newborn nose. One can hypothesize that the inflow area in human noses is a morphological adaptation in the changed length-height-ratio of the nasal cavity.

Efficacy of confrontational counselling for smoking cessation in smokers with previously undiagnosed mild to moderate airflow limitation: study protocol of a randomized controlled trial.

PubMed

Kotz, Daniel; Wesseling, Geertjan; Huibers, Marcus J H; van Schayck, Onno C P

2007-11-15

The use of spirometry for early detection of chronic obstructive pulmonary disease (COPD) is still an issue of debate, particularly because of a lack of convincing evidence that spirometry has an added positive effect on smoking cessation. We hypothesise that early detection of COPD and confrontation with spirometry for smoking cessation may be effective when applying an approach we have termed "confrontational counselling"; a patient-centred approach which involves specific communication skills and elements of cognitive therapy. An important aspect is to confront the smoker with his/her airflow limitation during the counselling sessions. The primary objective of this study is to test the efficacy of confrontational counselling in comparison to regular health education and promotion for smoking cessation delivered by specialized respiratory nurses in current smokers with previously undiagnosed mild to moderate airflow limitation. The study design is a randomized controlled trial comparing confrontational counselling delivered by a respiratory nurse combined with nortriptyline for smoking cessation (experimental group), health education and promotion delivered by a respiratory nurse combined with nortriptyline for smoking cessation (control group 1), and "care as usual" delivered by the GP (control group 2). Early detection of smokers with mild to moderate airflow limitation is achieved by means of a telephone interview in combination with spirometry. Due to a comparable baseline risk of airflow limitation and motivation to quit smoking, and because of the standardization of number, duration, and scheduling of counselling sessions between the experimental group and control group 1, the study enables to assess the "net" effect of confrontational counselling. The study has been ethically approved and registered. Ethical as well as methodological considerations of the study are discussed in this protocol. A significant and relevant effect of confrontational counselling would provide an argument in favour of early detection of current smokers with airflow limitation. Successful treatment of tobacco dependence in respiratory patients requires repeated intensive interventions. The results of this study may also show that respiratory nurses are able to deliver this treatment and that intensive smoking cessation counselling is more feasible. : Netherlands Trial Register (ISRCTN 64481813).

Inflammatory Biomarkers Predict Airflow Obstruction After Exposure to World Trade Center Dust

PubMed Central

Nolan, Anna; Naveed, Bushra; Comfort, Ashley L.; Ferrier, Natalia; Hall, Charles B.; Kwon, Sophia; Kasturiarachchi, Kusali J.; Cohen, Hillel W.; Zeig-Owens, Rachel; Glaser, Michelle S.; Webber, Mayris P.; Aldrich, Thomas K.; Rom, William N.; Kelly, Kerry; Prezant, David J.

2012-01-01

Background: The World Trade Center (WTC) collapse on September 11, 2001, produced airflow obstruction in a majority of firefighters receiving subspecialty pulmonary evaluation (SPE) within 6.5 years post-September 11, 2001. Methods: In a cohort of 801 never smokers with normal pre-September 11, 2001, FEV1, we correlated inflammatory biomarkers and CBC counts at monitoring entry within 6 months of September 11, 2001, with a median FEV1 at SPE (34 months; interquartile range, 25-57). Cases of airflow obstruction had FEV1 less than the lower limit of normal (LLN) (100 of 801; 70 of 100 had serum), whereas control subjects had FEV1 greater than or equal to LLN (153 of 801; 124 of 153 had serum). Results: From monitoring entry to SPE years later, FEV1 declined 12% in cases and increased 3% in control subjects. Case subjects had elevated serum macrophage derived chemokine (MDC), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor, and interferon inducible protein-10 levels. Elevated GM-CSF and MDC increased the risk for subsequent FEV1 less than LLN by 2.5-fold (95% CI, 1.2-5.3) and 3.0-fold (95% CI, 1.4-6.1) in a logistic model adjusted for exposure, BMI, age on September 11, 2001, and polymorphonuclear neutrophils. The model had sensitivity of 38% (95% CI, 27-51) and specificity of 88% (95% CI, 80-93). Conclusions: Inflammatory biomarkers can be risk factors for airflow obstruction following dust and smoke exposure. Elevated serum GM-CSF and MDC levels soon after WTC exposure were associated with increased risk of airflow obstruction in subsequent years. Biomarkers of inflammation may help identify pathways producing obstruction after irritant exposure. PMID:21998260

Clinical characterization of children with resistant airflow obstruction, a multicenter study.

PubMed

Krishnan, Sankaran; Dozor, Allen J; Bacharier, Leonard; Lang, Jason E; Irvin, Charles G; Kaminsky, David; Farber, Harold J; Gerald, Lynn; Brown, Mark; Holbrook, Janet T; Wise, Robert A; Ryu, Julie; Bose, Sonali; Yasin, Razan; Saams, Joy; Henderson, Robert J; Teague, William G

2018-05-17

To characterize a cohort of children with airflow limitation resistant to bronchodilator (BD) therapy. Pulmonary function tests performed in children 6-17 years of age at 15 centers in a clinical research consortium were screened for resistant airflow limitation, defined as a post-BD FEV 1 and/or an FEV 1 /FVC less than the lower limits of normal. Demographic and clinical data were analyzed for associations with pulmonary function. 582 children were identified. Median age was 13 years (IQR: 11, 16), 60% were males; 62% were Caucasian, 28% were African-American; 19% were obese; 32% were born prematurely and 21% exposed to second hand smoke. Pulmonary diagnoses included asthma (93%), prior significant pneumonia (28%), and bronchiectasis (5%). 65% reported allergic rhinitis, and 11% chronic sinusitis. Subjects without a history of asthma had significantly lower post-BD FEV 1 % predicted (p = 0.008). Subjects without allergic rhinitis had lower post-BD FEV 1 % predicted (p = 0.003). Children with allergic rhinitis, male sex, obesity and Black race had better pulmonary function post-BD. There was lower pulmonary function in children after age 11 years without a history of allergic rhinitis, as compared to those with a history of allergic rhinitis. The most prevalent diagnosis in children with BD-resistant airflow limitation is asthma. Allergic rhinitis and premature birth are common co-morbidities. Children without a history of asthma, as well as those with asthma but no allergic rhinitis, had lower pulmonary function. Children with BD-resistant airflow limitation may represent a sub-group of children with persistent obstruction and high risk for life-long airway disease.

Effects of Airflow and Changing Humidity on the Aerosolization of Respirable Fungal Fragments and Conidia of Botrytis cinerea

PubMed Central

2012-01-01

The purpose of this study was to investigate the aerosolization of particles (micro- and macroconidia and fragments) from Botrytis cinerea cultures in relation to potential human inhalation in indoor environments. The influence of the following factors on the aerosolization of B. cinerea particles was studied: exposure to airflow, relative humidity (rh), changing rh, and plant or building materials. The aerodynamic diameter (da) and the respirable fraction of the aerosolized particles were determined. Conidia and fragments of B. cinerea were not aerosolized as a response to a decrease in the rh. In contrast, both micro- and macroconidia and fungal fragments were aerosolized when exposed to an airflow of 1.5 m s−1 or 0.5 m s−1. Significantly more particles of microconidial size and fragment size were aerosolized at a low rh (18 to 40% rh) than at a higher rh (60 to 80% rh) when cultures were exposed to airflow. The size of the respirable fraction of the aerosolized particles was dependent on the rh but not on the growth material. At high rh, about 30% of the aerosolized particles were of respirable size, while at low rh, about 70% were of respirable size. During low rh, more fungal (1→3)-β-d-glucan and chitinase were aerosolized than during high rh. In conclusion, exposure to external physical forces such as airflow is necessary for the aerosolization of particles from B. cinerea. The amount and size distribution are highly affected by the rh, and more particles of respirable sizes were aerosolized at low rh than at high rh. PMID:22447608

Advances in sublimation studies for particles of explosives

NASA Astrophysics Data System (ADS)

Furstenberg, Robert; Nguyen, Viet; Fischer, Thomas; Abrishami, Tara; Papantonakis, Michael; Kendziora, Chris; Mott, David R.; McGill, R. Andrew

2015-05-01

When handling explosives, or related surfaces, the hands routinely become contaminated with particles of explosives and related materials. Subsequent contact with a solid surface results in particle crushing and deposition. These particles provide an evidentiary trail which is useful for security applications. As such, the opto-physico-chemical characteristics of these particles are critical to trace explosives detection applications in DOD or DHS arenas. As the persistence of these particles is vital to their forensic exploitation, it is important to understand which factors influence their persistence. The longevity or stability of explosives particles on a substrate is a function of several environmental parameters or particle properties including: Vapor pressure, particle geometry, airflow, particle field size, substrate topography, humidity, reactivity, adlayers, admixtures, particle areal density, and temperature. In this work we deposited particles of 2,4-dinitrotoluene on standard microscopy glass slides by particle sieving and studied their sublimation as a function of airflow velocity, areal particle density and particle field size. Analysis of 2D microscopic images was used to compute and track particle size and geometrical characteristics. The humidity, temperature and substrate type were kept constant for each experiment. A custom airflow cell, using standard microscopy glass slide, allowed in-situ photomicroscopy. Areal particle densities and airflow velocities were selected to provide relevant loadings and flow velocities for a range of potential applications. For a chemical of interest, we define the radial sublimation velocity (RSV) for the equivalent sphere of a particle as the parameter to characterize the sublimation rate. The RSV is a useful parameter because it is independent of particle size. The sublimation rate for an ensemble of particles was found to significantly depend on airflow velocity, the areal density of the particles, and the particle field size. To compare sublimation studies these parameters must be known.

Genome-Wide Association Studies Identify CHRNA5/3 and HTR4 in the Development of Airflow Obstruction

PubMed Central

Shrine, Nick R. G.; Loehr, Laura R.; Zhao, Jing Hua; Manichaikul, Ani; Lopez, Lorna M.; Smith, Albert Vernon; Heckbert, Susan R.; Smolonska, Joanna; Tang, Wenbo; Loth, Daan W.; Curjuric, Ivan; Hui, Jennie; Latourelle, Jeanne C.; Henry, Amanda P.; Aldrich, Melinda; Bakke, Per; Beaty, Terri H.; Bentley, Amy R.; Borecki, Ingrid B.; Brusselle, Guy G.; Burkart, Kristin M.; Chen, Ting-hsu; Couper, David; Crapo, James D.; Davies, Gail; Dupuis, Josée; Franceschini, Nora; Gulsvik, Amund; Hancock, Dana B.; Harris, Tamara B.; Hofman, Albert; Imboden, Medea; James, Alan L.; Khaw, Kay-Tee; Lahousse, Lies; Launer, Lenore J.; Litonjua, Augusto; Liu, Yongmei; Lohman, Kurt K.; Lomas, David A.; Lumley, Thomas; Marciante, Kristin D.; McArdle, Wendy L.; Meibohm, Bernd; Morrison, Alanna C.; Musk, Arthur W.; Myers, Richard H.; North, Kari E.; Postma, Dirkje S.; Psaty, Bruce M.; Rich, Stephen S.; Rivadeneira, Fernando; Rochat, Thierry; Rotter, Jerome I.; Artigas, María Soler; Starr, John M.; Uitterlinden, André G.; Wareham, Nicholas J.; Wijmenga, Cisca; Zanen, Pieter; Province, Michael A.; Silverman, Edwin K.; Deary, Ian J.; Palmer, Lyle J.; Cassano, Patricia A.; Gudnason, Vilmundur; Barr, R. Graham; Loos, Ruth J. F.; Strachan, David P.; London, Stephanie J.; Boezen, H. Marike; Probst-Hensch, Nicole; Gharib, Sina A.; Hall, Ian P.; O’Connor, George T.; Tobin, Martin D.; Stricker, Bruno H.

2012-01-01

Rationale: Genome-wide association studies (GWAS) have identified loci influencing lung function, but fewer genes influencing chronic obstructive pulmonary disease (COPD) are known. Objectives: Perform meta-analyses of GWAS for airflow obstruction, a key pathophysiologic characteristic of COPD assessed by spirometry, in population-based cohorts examining all participants, ever smokers, never smokers, asthma-free participants, and more severe cases. Methods: Fifteen cohorts were studied for discovery (3,368 affected; 29,507 unaffected), and a population-based family study and a meta-analysis of case-control studies were used for replication and regional follow-up (3,837 cases; 4,479 control subjects). Airflow obstruction was defined as FEV1 and its ratio to FVC (FEV1/FVC) both less than their respective lower limits of normal as determined by published reference equations. Measurements and Main Results: The discovery meta-analyses identified one region on chromosome 15q25.1 meeting genome-wide significance in ever smokers that includes AGPHD1, IREB2, and CHRNA5/CHRNA3 genes. The region was also modestly associated among never smokers. Gene expression studies confirmed the presence of CHRNA5/3 in lung, airway smooth muscle, and bronchial epithelial cells. A single-nucleotide polymorphism in HTR4, a gene previously related to FEV1/FVC, achieved genome-wide statistical significance in combined meta-analysis. Top single-nucleotide polymorphisms in ADAM19, RARB, PPAP2B, and ADAMTS19 were nominally replicated in the COPD meta-analysis. Conclusions: These results suggest an important role for the CHRNA5/3 region as a genetic risk factor for airflow obstruction that may be independent of smoking and implicate the HTR4 gene in the etiology of airflow obstruction. PMID:22837378

Beach-dune dynamics: Spatio-temporal patterns of aeolian sediment transport under complex offshore airflow

NASA Astrophysics Data System (ADS)

Lynch, K.; Jackson, D.; Delgado-Fernandez, I.; Cooper, J. A.; Baas, A. C.; Beyers, M.

2010-12-01

This study examines sand transport and wind speed across a beach at Magilligan Strand, Northern Ireland, under offshore wind conditions. Traditionally the offshore component of local wind regimes has been ignored when quantifying beach-dune sediment budgets, with the sheltering effect of the foredune assumed to prohibit grain entrainment on the adjoining beach. Recent investigations of secondary airflow patterns over coastal dunes have suggested this may not be the case, that the turbulent nature of the airflow in these zones enhances sediment transport potential. Beach sediment may be delivered to the dune toe by re-circulating eddies under offshore winds in coastal areas, which may explain much of the dynamics of aeolian dunes on coasts where the dominant wind direction is offshore. The present study investigated aeolian sediment transport patterns under an offshore wind event. Empirical data were collected using load cell traps, for aeolian sediment transport, co-located with 3-D ultrasonic anemometers. The instrument positioning on the sub-aerial beach was informed by prior analysis of the airflow patterns using computational fluid dynamics. The array covered a total beach area of 90 m alongshore by 65 m cross-shore from the dune crest. Results confirm that sediment transport occurred in the ‘sheltered’ area under offshore winds. Over short time and space scales the nature of the transport is highly complex; however, preferential zones for sand entrainment may be identified. Alongshore spatial heterogeneity of sediment transport seems to show a relationship to undulations in the dune crest, while temporal and spatial variations may also be related to the position of the airflow reattachment zone. These results highlight the important feedbacks between flow characteristics and transport in a complex three dimensional surface.

Experimental study of airflow characteristics of stratum ventilation in a multi-occupant room with comparison to mixing ventilation and displacement ventilation.

PubMed

Cheng, Y; Lin, Z

2015-12-01

The motivation of this study is stimulated by a lack of knowledge about the difference of airflow characteristics between a novel air distribution method [i.e., stratum ventilation (SV)] and conventional air distribution methods [i.e., mixing ventilation (MV) and displacement ventilation (DV)]. Detailed air velocity and temperature measurements were conducted in the occupied zone of a classroom with dimensions of 8.8 m (L) × 6.1 m (W) × 2.4 m (H). Turbulence intensity and power spectrum of velocity fluctuation were calculated using the measured data. Thermal comfort and cooling efficiency were also compared. The results show that in the occupied zone, the airflow characteristics among MV, DV, and SV are different. The turbulent airflow fluctuation is enhanced in this classroom with multiple thermal manikins due to thermal buoyancy and airflow mixing effect. Thermal comfort evaluations indicate that in comparison with MV and DV, a higher supply air temperature should be adopted for SV to achieve general thermal comfort with low draft risk. Comparison of the mean air temperatures in the occupied zone reveals that SV is of highest cooling efficiency, followed by DV and then MV. This study reports the unique profiles of flow, temperature, turbulence intensity, and power spectrum of stratum ventilation, which can have a number of implications for both knowledge and understanding of the flow characteristics in a stratum-ventilated room. With respect to the former, it expounds the fundamental characteristics of this air distribution method; and with respect to the latter, it reveals the mechanism of thermal comfort and energy saving under stratum ventilation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Enhanced upper respiratory tract airflow and head fanning reduce brain temperature in brain-injured, mechanically ventilated patients: a randomized, crossover, factorial trial.

PubMed

Harris, B A; Andrews, P J D; Murray, G D

2007-01-01

Heat loss from the upper airways and through the skull are physiological mechanisms of brain cooling which have not been fully explored clinically. This randomized, crossover, factorial trial in 12 brain-injured, orally intubated patients investigated the effect of enhanced nasal airflow (high flow unhumidified air with 20 p.p.m. nitric oxide gas) and bilateral head fanning on frontal lobe brain temperature and selective brain cooling. After a 30 min baseline, each patient received the four possible combinations of the interventions--airflow, fanning, both together, no intervention--in randomized order. Each combination was delivered for 30 min and followed by a 30 min washout, the last 5 min of which provided the baseline for the next intervention. The difference in mean brain temperature over the last 5 min of the preceding washout minus the mean over the last 5 min of intervention, was 0.15 degrees C with nasal airflow (P=0.001, 95% CI 0.06-0.23 degrees C) and 0.26 degrees C with head fanning (P<0.001, 95% CI 0.17-0.34 degrees C). The estimate of the combined effect of airflow and fanning on brain temperature was 0.41 degrees C. Selective brain cooling did not occur. Physiologically, this study demonstrates that heat loss through the upper airways and through the skull can reduce parenchymal brain temperature in brain-injured humans and the onset of temperature reduction is rapid. Clinically, in ischaemic stroke, a temperature decrease of 0.27 degrees C may reduce the relative risk of poor outcome by 10-20%. Head fanning may have the potential to achieve a temperature decrease of this order.

Glottal Adduction and Subglottal Pressure in Singing.

PubMed

Herbst, Christian T; Hess, Markus; Müller, Frank; Švec, Jan G; Sundberg, Johan

2015-07-01

Previous research suggests that independent variation of vocal loudness and glottal configuration (type and degree of vocal fold adduction) does not occur in untrained speech production. This study investigated whether these factors can be varied independently in trained singing and how subglottal pressure is related to average glottal airflow, voice source properties, and sound level under these conditions. A classically trained baritone produced sustained phonations on the endoscopic vowel [i:] at pitch D4 (approximately 294 Hz), exclusively varying either (a) vocal register; (b) phonation type (from "breathy" to "pressed" via cartilaginous adduction); or (c) vocal loudness, while keeping the others constant. Phonation was documented by simultaneous recording of videokymographic, electroglottographic, airflow and voice source data, and by percutaneous measurement of relative subglottal pressure. Register shifts were clearly marked in the electroglottographic wavegram display. Compared with chest register, falsetto was produced with greater pulse amplitude of the glottal flow, H1-H2, mean airflow, and with lower maximum flow declination rate (MFDR), subglottal pressure, and sound pressure. Shifts of phonation type (breathy/flow/neutral/pressed) induced comparable systematic changes. Increase of vocal loudness resulted in increased subglottal pressure, average flow, sound pressure, MFDR, glottal flow pulse amplitude, and H1-H2. When changing either vocal register or phonation type, subglottal pressure and mean airflow showed an inverse relationship, that is, variation of glottal flow resistance. The direct relation between subglottal pressure and airflow when varying only vocal loudness demonstrated independent control of vocal loudness and glottal configuration. Achieving such independent control of phonatory control parameters would be an important target in vocal pedagogy and in voice therapy. Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Quality of life in smokers: focus on functional limitations rather than on lung function?

PubMed Central

Geijer, Roeland MM; Sachs, Alfred PE; Verheij, Theo JM; Kerstjens, Huib AM; Kuyvenhoven, Marijke M; Hoes, Arno W

2007-01-01

Background The Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification of severity of chronic obstructive pulmonary disease (COPD) is based solely on obstruction and does not capture physical functioning. The hypothesis that the Medical Research Council (MRC) dyspnoea scale would correlate better with quality of life than the level of airflow limitation was examined. Aim To study the associations between quality of life in smokers and limitations in physical functioning (MRC dyspnoea scale) and, quality of life and airflow limitation (GOLD COPD stages). Design Cross-sectional study. Setting The city of IJsselstein, a small town in the centre of The Netherlands. Method Male smokers aged 40–65 years without a prior diagnosis of COPD and enlisted with a general practice, participated in this study. Quality of life was assessed by means of a generic (SF–36) and a disease-specific, questionnaire (QOLRIQ). Results A total of 395 subjects (mean age 55.4 years, pack years 27.1) performed adequate spirometry and completed the questionnaires. Limitations of physical functioning according to the MRC dyspnoea scale were found in 25.1 % (99/395) of the participants and airflow limitation in 40.2% (159/395). The correlations of limitations of physical functioning with all quality-of-life components were stronger than the correlations of all quality-of-life subscales with the severity of airflow limitation. Conclusion In middle-aged smokers the correlation of limitations of physical functioning (MRC dyspnoea scale) with quality of life was stronger than the correlation of the severity of airflow limitation with quality of life. Future staging systems of severity of COPD should capture this and not rely on forced expiratory volume in one second (FEV1) alone. PMID:17550673

Design and control of a variable geometry turbofan with an independently modulated third stream

NASA Astrophysics Data System (ADS)

Simmons, Ronald J.

Emerging 21st century military missions task engines to deliver the fuel efficiency of a high bypass turbofan while retaining the ability to produce the high specific thrust of a low bypass turbofan. This study explores the possibility of satisfying such competing demands by adding a second independently modulated bypass stream to the basic turbofan architecture. This third stream can be used for a variety of purposes including: providing a cool heat sink for dissipating aircraft heat loads, cooling turbine cooling air, and providing a readily available stream of constant pressure ratio air for lift augmentation. Furthermore, by modulating airflow to the second and third streams, it is possible to continuously match the engine's airflow demand to the inlet's airflow supply thereby reducing spillage and increasing propulsive efficiency. This research begins with a historical perspective of variable cycle engines and shows a logical progression to proposed architectures. Then a novel method for investigating optimal performance is presented which determines most favorable on design variable geometry settings, most beneficial moment to terminate flow holding, and an optimal scheduling of variable features for fuel efficient off design operation. Mission analysis conducted across the three candidate missions verifies that these three stream variable cycles can deliver fuel savings in excess of 30% relative to a year 2000 reference turbofan. This research concludes by evaluating the relative impact of each variable technology on the performance of adaptive engine architectures. The most promising technologies include modulated turbine cooling air, variable high pressure turbine inlet area and variable third stream nozzle throat area. With just these few features it is possible to obtain nearly optimal performance, including 90% or more of the potential fuel savings, with far fewer variable features than are available in the study engine. It is abundantly clear that three stream variable architectures can significantly outperform existing two stream turbofans in both fuel efficiency and at the vehicle system level with only a modest increase in complexity and weight. Such engine architectures should be strongly considered for future military applications.

The influence of wind speed on airflow and fine particle transport within different building layouts of an industrial city.

PubMed

Mei, Dan; Wen, Meng; Xu, Xuemei; Zhu, Yuzheng; Xing, Futang

2018-04-20

In atmospheric environment, the layout difference of urban buildings has a powerful influence on accelerating or inhibiting the dispersion of particle matters (PM). In industrial cities, buildings of variable heights can obstruct the diffusion of PM from industrial stacks. In this study, PM dispersed within building groups was simulated by Reynolds-averaged Navier-Stokes equations coupled Lagrangian approach. Four typical street building arrangements were used: (a) a low-rise building block with Height/base H/b = 1 (b = 20 m); (b) step-up building layout (H/b = 1, 2, 3, 4); (c) step-down building layout (H/b = 4, 3, 2, 1); (d) high-rise building block (H/b = 5). Profiles of stream functions and turbulence intensity were used to examine the effect of various building layouts on atmospheric airflow. Here, concepts of particle suspension fraction and concentration distribution were used to evaluate the effect of wind speed on fine particle transport. These parameters showed that step-up building layouts accelerated top airflow and diffused more particles into street canyons, likely having adverse effects on resident health. In renewal old industry areas, the step-down building arrangement which can hinder PM dispersion from high-level stacks should be constructed preferentially. High turbulent intensity results in formation of a strong vortex that hinders particles into the street canyons. It is found that an increase in wind speed enhanced particle transport and reduced local particle concentrations, however, it did not affect the relative location of high particle concentration zones, which are related to building height and layout. This study has demonstrated the height variation and layout of urban architecture affect the local concentration distribution of particulate matter (PM) in the atmosphere and for the first time that wind velocity has particular effects on PM transport in various building groups. The findings may have general implications in optimization the building layout based on particle transport characteristics during the renewal of industrial cities. For city planners, the results and conclusions are useful for improving the local air quality. The study method also can be used to calculate the explosion risk of industrial dust for people who live in industrial cities.

Determination of air movement in stored grain as a factor in dynamic dispersion and distribution patterns of gaseous pesticides (fumigants).

PubMed

Berck, B

1975-05-01

The new research reported herein was motivated by variations in distribution-persistence patterns of fumigant residues (BERCK, 1974). The current developmental program is still underway. In the meantime, measurement of picoliter amounts of SF6 in air by GC equipped with a Ni63 EC detector has been proven useful over an airflow range of 10(-4) to 50 mph, representing a factor of 500,000 in differences in air velocity. Diverse applications have been outlined herein. This is the first case on record where measurement of unassisted airflow in the interstitial air of stored grain has been successfully executed, and which enabled determination of airflow speeds in the range of 0.5 to 7.5 times 10(-4) mph (=3 to 45 inches per hour).

Effects of oblique air flow on burning rates of square ethanol pool fires.

PubMed

Tao, Changfa; He, Yaping; Li, Yuan; Wang, Xishi

2013-09-15

The effects of downward airflow on the burning rate and/or burning intensity of square alcohol pool fires for different airflow speeds and directions have been studied experimentally in an inclined wind tunnel. An interesting flame-wrapping phenomenon, caused by impingement of air flow, was observed. The mass burning intensity was found to increase with the airflow speed and the impinging angle. The fuel pan rim temperatures were also measured to study the effect of wind direction and speed on heat transfer from the flame to the fuel source. A model based on heat transfer analysis was developed to correlate the burning intensity with the pan rim characteristic temperature. A good correlation was established between the model results and the experimental results. Copyright © 2013 Elsevier B.V. All rights reserved.

On the Uses of Full-Scale Schlieren Flow Visualization

NASA Astrophysics Data System (ADS)

Settles, G. S.; Miller, J. D.; Dodson-Dreibelbis, L. J.

2000-11-01

A lens-and-grid-type schlieren system using a very large grid as a light source was described at earlier APS/DFD meetings. With a field-of-view of 2.3x2.9 m (7.5x9.5 feet), it is the largest indoor schlieren system in the world. Still and video examples of several full-scale airflows and heat-transfer problems visualized thus far will be shown. These include: heating and ventilation airflows, flows due to appliances and equipment, the thermal plumes of people, the aerodynamics of an explosive trace detection portal, gas leak detection, shock wave motion associated with aviation security problems, and heat transfer from live crops. Planned future projects include visualizing fume-hood and grocery display freezer airflows and studying the dispersion of insect repellent plumes at full scale.

Impact of surface disinfection and sterile draping of furniture on room air quality in a cardiac procedure room with a ventilation and air-conditioning system (extrusion airflow, cleanroom class 1b (DIN 1946-4))

PubMed Central

Below, Harald; Ryll, Sylvia; Empen, Klaus; Dornquast, Tina; Felix, Stefan; Rosenau, Heike; Kramer, Sebastian; Kramer, Axel

2010-01-01

In a cardiac procedure room, ventilated by a ventilation and air-conditioning system with turbulent mixed airflow, a protection zone in the operating area could be defined through visualization of airflows. Within this protection zone, no turbulence was detectable in the room air. Under the given conditions, disinfection of all surfaces including all furniture and equipment after the last operation and subsequent draping of furniture and all equipment that could not be removed from the room with sterile surgical drapes improved the indoor room air quality from cleanroom class C to cleanroom class B. This also allows procedures with elevated requirements to be performed in room class 1b. PMID:20941336

A Computational Study of the Respiratory Airflow Characteristics in Normal and Obstructed Human Airways

DTIC Science & Technology

2014-01-01

normal and three different obstructed airway geometries, consisting of symmetric, asym- metric, and random obstructions. Fig. 2 shows the geometric ...normal and obstructed airways Airway resistance is a measure of the opposition to the airflow caused by geometric properties, such as airway obstruction...pressure drops. Resistance values were dependent on the degree and geometric distribution of the obstruction sites. In the symmetric obstruction model

Asbestos penetration test system for clothing materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradley, O.D.; Stampfer, J.F.; Sandoval, A.N.

1997-04-01

For hazardous work such as asbestos abatement, there is a need to assess protective clothing fabrics and seam constructions to assure an adequate barrier against hazardous material. The penetration of aerosols through fabrics usually is measured by challenging fabric samples with an aerosol stream at a constant specified airflow. To produce the specified airflow, pressure differentials across the samples often are higher than exist in a work environment. This higher airflow results in higher aerosol velocities through the fabric and, possibly, measured penetration values not representative of those actually experienced in the field. The objective of the reported work wasmore » to develop a test method that does not require these higher airflows. The authors have designed and fabricated a new system that tests fabric samples under a low, constant, specified pressure differential across the samples. This differential is adjustable from tenths of a mm Water Gauge (hundredths of an in WG) to over 25-mm WG (1-in WG). The system operates at a pressure slightly lower than its surroundings. Although designed primarily for asbestos, the system is equally applicable to the testing of other aerosols by changing the aerosol generator and detector. Through simple modification of the sample holders, the test apparatus would be capable of evaluating seam and closure constructions.« less

Case-finding of chronic obstructive pulmonary disease with questionnaire, peak flow measurements and spirometry: a cross-sectional study

PubMed Central

2014-01-01

Background Spirometry is commonly accepted as the gold standard for the diagnosis of COPD, but the reality remains that quality assured spirometry is not or cannot be provided universally around the globe. Adding PEF measurement to a screening questionnaire may rule out airflow limitation compatible with COPD rationalizing spirometry testing. Methods We conducted a cross-sectional survey in a sample of individuals 40–80 yrs. old in Dubai, UAE. They were invited to answer a short socio-demographic questionnaire including a report on current, past history of smoking, and had PEF measured, then they conducted spirometry to identify airflow limitation compatible with COPD. Results Overall, 525 (91.0%) participants performed PEF and spirometry (68% male, with a mean age of 59 years, 17% UAE Nationals), 24% reported smoking of different sorts. Overall, 68 participants (12.9%, 95% C.I. 10.3% to 16.1%) had airflow limitation compatible with COPD. PEFR alone identified 141participants with airflow limitation compatible with COPD, with specificity of 80% and sensitivity of 73.5%. Conclusions PEFR could be an easy, cheap, and non-biased tool to assist with the case-finding of COPD before confirmation with spirometry. PMID:24739210

Method of controlling a variable geometry type turbocharger

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirabayashi, Y.

1988-08-23

This patent describes a method of controlling the supercharging pressure of a variable geometry type turbocharger having a bypass, comprising the following steps which are carried out successively: receiving signals from an engine speed sensor and from an engine knocking sensor; receiving a signal from a throttle valve sensor; judging whether or not an engine is being accelerated, and proceeding to step below if the engine is being accelerated and to step below if the engine is not being accelerated, i.e., if the engine is in a constant speed operation; determining a first correction value and proceeding to step below;more » judging whether or not the engine is knocking, and proceeding to step (d) if knocking is occurring and to step (f) below if no knocking is occurring; determining a second correction value and proceeding to step; receiving signals from the engine speed sensor and from an airflow meter which measures the quantity of airflow to be supplied to the engine; calculating an airflow rate per engine revolution; determining a duty valve according to the calculated airflow rate; transmitting the corrected duty value to control means for controlling the geometry of the variable geometry type turbocharger and the opening of bypass of the turbocharger, thereby controlling the supercharging pressure of the turbocharger.« less

Airflow and temperature distribution inside the maxillary sinus: a computational fluid dynamics simulation.

PubMed

Zang, Hongrui; Liu, Yingxi; Han, Demin; Zhang, Luo; Wang, Tong; Sun, Xiuzhen; Li, Lifeng

2012-06-01

The airflow velocity and flux in maxillary sinuses were much lower than those in the nasal cavity, and the temperature in maxillary sinuses was much higher than the temperature in the middle meatus. With the increase of maximum diameter of the ostium, the above indices changed little. The purpose of the paper was to investigate, first, the flow and temperature distribution inside normal maxillary sinus in inspiration, and second, flow and temperature alteration with the increase of maximum ostium diameter. Three-dimensional models with nasal cavities and bilateral maxillary sinuses were constructed for computational fluid dynamics analysis. Virtual surgeries were implemented for the maxillary ostium, the maximum diameters of which were 8, 10, 12, and 15 mm, respectively. The finite volume method was used for numerical simulation. The indices of velocity, pressure, vector, and temperature were processed and compared between models. The airflow velocity in maxillary sinuses (average velocity 0.062 m/s) was much lower than that in the middle meatus (average velocity 3.26 m/s). With the increase of ostium diameter, airflow characteristics distributed in the maxillary sinuses changed little. The normal temperature in the maxillary sinus remained almost constant at 34°C and changed little with the increase of ostium diameter.

Hybridized electromagnetic-triboelectric nanogenerator for scavenging air-flow energy to sustainably power temperature sensors.

PubMed

Wang, Xue; Wang, Shuhua; Yang, Ya; Wang, Zhong Lin

2015-04-28

We report a hybridized nanogenerator with dimensions of 6.7 cm × 4.5 cm × 2 cm and a weight of 42.3 g that consists of two triboelectric nanogenerators (TENGs) and two electromagnetic generators (EMGs) for scavenging air-flow energy. Under an air-flow speed of about 18 m/s, the hybridized nanogenerator can deliver largest output powers of 3.5 mW for one TENG (in correspondence of power per unit mass/volume: 8.8 mW/g and 14.6 kW/m(3)) at a loading resistance of 3 MΩ and 1.8 mW for one EMG (in correspondence of power per unit mass/volume: 0.3 mW/g and 0.4 kW/m(3)) at a loading resistance of 2 kΩ, respectively. The hybridized nanogenerator can be utilized to charge a capacitor of 3300 μF to sustainably power four temperature sensors for realizing self-powered temperature sensor networks. Moreover, a wireless temperature sensor driven by a hybridized nanogenerator charged Li-ion battery can work well to send the temperature data to a receiver/computer at a distance of 1.5 m. This work takes a significant step toward air-flow energy harvesting and its potential applications in self-powered wireless sensor networks.

Measuring Device for Air Speed in Macroporous Media and Its Application Inside Apple Storage Bins

PubMed Central

Geyer, Martin; Praeger, Ulrike; Scaar, Holger; Neuwald, Daniel A.; Gottschalk, Klaus

2018-01-01

In cold storage facilities of fruit and vegetables, airflow is necessary for heat removal. The design of storage facilities influences the air speed in the surrounding of the product. Therefore, knowledge about airflow next to the product is important to plan the layout of cold stores adapted to the requirements of the products. A new sensing device (ASL, Air speed logger) is developed for omnidirectional measurement of air speed between fruit or vegetables inside storage bins or in bulk. It consists of four interconnected plastic spheres with 80 mm diameter each, adapted to the size of apple fruit. In the free space between the spheres, silicon diodes are fixed for the airflow measurement based on a calorimetric principle. Battery and data logger are mounted inside the spheres. The device is calibrated in a wind tunnel in a measuring range of 0–1.3 m/s. Air speed measurements in fruit bulks on laboratory scale and in an industrial fruit store show air speeds in gaps between fruit with high stability at different airflow levels. Several devices can be placed between stored products for determination of the air speed distribution inside bulks or bin stacks in a storage room. PMID:29438339

No need to change the skin knife in modern arthroplasty surgery.

PubMed

Ottesen, C; Skovby, A; Troelsen, A; Specht, C; Friis-Møller, A; Husted, H

2014-08-01

Earlier studies have found varying contamination rates using separate skin and deep knives in total hip (THA) and total knee (TKA) arthroplasty surgery. Previous studies were primarily conducted in the setting of concomitant use of laminar airflow and/or plastic adhesive draping. This has lead to conflicting conclusions regarding discarding the skin knife or not. This study evaluates the prevalence of contamination of a separate skin knife using modern antiseptic technique in primary THA and TKA without laminar airflow. Three knives from each primary THA and TKA surgery in non-laminar airflow operating rooms were collected: one used for the skin, one used for deeper tissues and one control knife. A total of 831 knife blades from 277 patients were cultured 12 days. Contamination of the skin knife was found in eight patients (2.8 %), contamination of the "deep" knife in five patients (1.8 %) and contamination of the control knife in five patients (1.8 %). No patient developed an infection with 1-year follow-up. Our findings suggest a very low rate of contamination of the skin knife using modern antiseptic technique without laminar airflow and/or plastic adhesive draping and do not support the use of a separate skin knife in arthroplasty surgery.

Cross-Sectional Analysis of the Utility of Pulmonary Function Tests in Predicting Emphysema in Ever-Smokers

PubMed Central

Hesselbacher, Sean E.; Ross, Robert; Schabath, Matthew B.; Smith, E. O’Brian; Perusich, Sarah; Barrow, Nadia; Smithwick, Pamela; Mammen, Manoj J.; Coxson, Harvey; Krowchuk, Natasha; Corry, David B.; Kheradmand, Farrah

2011-01-01

Emphysema is largely an under-diagnosed medical condition that can exist in smokers in the absence of airway obstruction. We aimed to determine the sensitivity and specificity of pulmonary function tests (PFTs) in assessing emphysema using quantitative CT scans as the reference standard. We enrolled 224 ever-smokers (current or former) over the age of 40. CT of thorax was used to quantify the low attenuation area (% emphysema), and to measure the standardized airway wall thickness. PFTs were used individually and in combination to predict their ability to discriminate radiographic emphysema. Significant emphysema (>7%) was detected in 122 (54%) subjects. Twenty six (21%) emphysema subjects had no evidence of airflow obstruction (FEV1/FVC ratio <70%), while all subjects with >23% emphysema showed airflow obstruction. The sensitivity and specificity of spirometry for detecting radiographic emphysema were 79% and 75%, respectively. Standardized airway wall thickness was increased in subjects with airflow obstruction, but did not correlate with emphysema severity. In this cohort of lifetime ever-smokers, PFTs alone were inadequate for diagnosing emphysema. Airway wall thickness quantified by CT morphometry was associated with airflow limitation, but not with emphysema indicating that the heterogeneous nature of lung disease in smokers may represent distinct phenotypes. PMID:21655122

Periodontitis is related to lung volumes and airflow limitation: a cross-sectional study.

PubMed

Holtfreter, Birte; Richter, Stefanie; Kocher, Thomas; Dörr, Marcus; Völzke, Henry; Ittermann, Till; Obst, Anne; Schäper, Christoph; John, Ulrich; Meisel, Peter; Grotevendt, Anne; Felix, Stephan B; Ewert, Ralf; Gläser, Sven

2013-12-01

This study aimed to assess the potential association of periodontal diseases with lung volumes and airflow limitation in a general adult population. Based on a representative population sample of the Study of Health in Pomerania (SHIP), 1463 subjects aged 25-86 years were included. Periodontal status was assessed by clinical attachment loss (CAL), probing depth and number of missing teeth. Lung function was measured using spirometry, body plethysmography and diffusing capacity of the lung for carbon monoxide. Linear regression models using fractional polynomials were used to assess associations between periodontal disease and lung function. Fibrinogen and high-sensitivity C-reactive protein (hs-CRP) were evaluated as potential intermediate factors. After full adjustment for potential confounders mean CAL was significantly associated with variables of mobile dynamic and static lung volumes, airflow limitation and hyperinflation (p<0.05). Including fibrinogen and hs-CRP did not change coefficients of mean CAL; associations remained statistically significant. Mean CAL was not associated with total lung capacity and diffusing capacity of the lung for carbon monoxide. Associations were confirmed for mean probing depth, extent measures of CAL/probing depth and number of missing teeth. Periodontal disease was significantly associated with reduced lung volumes and airflow limitation in this general adult population sample. Systemic inflammation did not provide a mechanism linking both diseases.

Parametric study on the characteristics of a SDBD actuator with a serrated electrode

NASA Astrophysics Data System (ADS)

Gao, Guoqiang; Peng, Kaisheng; Dong, Lei; Wei, Wenfu; Wu, Guangning

2017-06-01

Active flow control based on surface dielectric barrier discharge (SDBD) has become a focus of research in recent years, due to its unique advantages and diverse potential applications. Compared with the conventional SDBD with straight electrodes, the serrated electrode-based SDBD has a great advantage due to its 3D flow topology. It is believed that the boundary layer separation of moving objects can be controlled more effectively with this new type of SDBD. In SDBD with a serrated electrode, the R (tip sharpness) and N (tip number per unit length) have a great influence on the discharge and induced airflow characteristics. In this paper, a parametric study of the characteristics of SDBD with a serrated electrode has been conducted with different ranges of R and N. Aspects of the power consumption, the steady medium temperature distribution, and the maximum induced airflow velocity have been investigated. The results indicate that there is a critical value of R and N where the maximum power consumption and induced airflow velocity are achieved. The uniformity of the steady temperature distribution of the medium surface is found to be more dependent on N. We found that the accelerating effects of the induced airflow can be evaluated with the Schlieren technique, which agree well with the results from the pitot tube.

Mass Median Plume Angle: A novel approach to characterize plume geometry in solution based pMDIs.

PubMed

Moraga-Espinoza, Daniel; Eshaghian, Eli; Smyth, Hugh D C

2018-05-30

High-speed laser imaging (HSLI) is the preferred technique to characterize the geometry of the plume in pressurized metered dose inhalers (pMDIs). However, current methods do not allow for simulation of inhalation airflow and do not use drug mass quantification to determine plume angles. To address these limitations, a Plume Induction Port Evaluator (PIPE) was designed to characterize the plume geometry based on mass deposition patterns. The method is easily adaptable to current pMDI characterization methodologies, uses similar calculations methods, and can be used under airflow. The effect of airflow and formulation on the plume geometry were evaluated using PIPE and HSLI. Deposition patterns in PIPE were highly reproducible and log-normal distributed. Mass Median Plume Angle (MMPA) was a new characterization parameter to describe the effective angle of the droplets deposited in the induction port. Plume angles determined by mass showed a significant decrease in size as ethanol increases which correlates to the decrease on vapor pressure in the formulation. Additionally, airflow significantly decreased the angle of the plumes when cascade impactor was operated under flow. PIPE is an alternative to laser-based characterization methods to evaluate the plume angle of pMDIs based on reliable drug quantification while simulating patient inhalation. Copyright © 2018. Published by Elsevier B.V.

Dyssynchronous breathing during arm but not leg exercise in patients with chronic airflow obstruction.

PubMed

Celli, B R; Rassulo, J; Make, B J

1986-06-05

Some patients with chronic airflow obstruction experience dyspnea with mild arm exercise but not with more-intense leg exercise. To investigate why these patients have limited endurance during arm exertion, we studied ventilatory responses to exercise with unsupported arms in 12 patients with chronic airflow obstruction (mean [+/- SD] forced expiratory volume in one second, 0.68 +/- 0.28 liters). Unloaded leg cycling was also studied for comparison. In the five patients who had the most severe airflow obstruction, arm exercise was limited by dyspnea after 3.3 +/- 0.7 minutes, and dyssynchronous thoracoabdominal breathing developed. In the other seven patients, arm exercise was limited by the sensation of muscle fatigue after 6.1 +/- 2.0 minutes (P less than 0.05), and dyssynchronous breathing did not occur. None of the 12 patients had dyssynchronous breathing during unloaded leg cycling. Maximal transdiaphragmatic pressure, a measure of diaphragmatic fatigue, declined similarly after arm and leg exercise in both groups. During unsupported arm work, the accessory muscles of inspiration help position the torso and arms. We hypothesize that the extra demand placed on these muscles during arm exertion leads to early fatigue, an increased load on the diaphragm, and dyssynchronous thoracoabdominal inspirations. This sequence may contribute to dyspnea and limited endurance during upper-extremity exercise.

Simulations of temporal patterns of oral airflow in men and women using a two-mass model of the vocal folds under dynamic control

NASA Astrophysics Data System (ADS)

Lucero, Jorge C.; Koenig, Laura L.

2005-03-01

In this study we use a low-dimensional laryngeal model to reproduce temporal variations in oral airflow produced by speakers in the vicinity of an abduction gesture. It attempts to characterize these temporal patterns in terms of biomechanical parameters such as glottal area, vocal fold stiffness, subglottal pressure, and gender differences in laryngeal dimensions. A two-mass model of the vocal folds coupled to a two-tube approximation of the vocal tract is fitted to oral airflow records measured in men and women during the production of /aha/ utterances, using the subglottal pressure, glottal width, and Q factor as control parameters. The results show that the model is capable of reproducing the airflow records with good approximation. A nonlinear damping characteristics is needed, to reproduce the flow variation at glottal abduction. Devoicing is achieved by the combined action of vocal fold abduction, the decrease of subglottal pressure, and the increase of vocal fold tension. In general, the female larynx has a more restricted region of vocal fold oscillation than the male one. This would explain the more frequent devoicing in glottal abduction-adduction gestures for /h/ in running speech by women, compared to men. .

Investigation of a robust tendon-sheath mechanism for flexible membrane wing application in mini-UAV

NASA Astrophysics Data System (ADS)

Lee, Shian; Tjahjowidodo, Tegoeh; Lee, Hsuchew; Lai, Benedict

2017-02-01

Two inherent issues manifest themselves in flying mini-unmanned aerial vehicles (mini-UAV) in the dense area at tropical climate regions, namely disturbances from gusty winds and limited space for deployment tasks. Flexible membrane wing (FMW) UAVs are seen to be potentials to mitigate these problems. FMWs are adaptable to gusty airflow as the wings are able to flex according to the gust load to reduce the effective angle-of-attack, thus, reducing the aerodynamic loads on the wing. On the other hand, the flexible structure is allowing the UAV to fold in a compact package, and later on, the mini-UAV can be deployed instantly from the storage tube, e.g. through a catapult mechanism. This paper discusses the development of an FMW UAV actuated by a tendon-sheath mechanism (TSM). This approach allows the wing to morph to generate a rolling moment, while still allowing the wing to fold. Dynamic characteristics of the mechanism that exhibits the strong nonlinear phenomenon of friction on TSM are modeled and compensated for. A feed-forward controller was implemented based on the identified nonlinear behavior to control the warping position of the wing. The proposed strategy is validated experimentally in a wind tunnel facility by creating a gusty environment that is imitating a realistic gusty condition based upon the results of computational fluid dynamics (CFD) simulation. The results demonstrate a stable and robust wing-warping actuation, even in gusty conditions. Accurate wing-warping can be achieved via the TSM, while also allowing the wings to fold.

Communist China. Section 23. Weather and Climate. Part 3 - North China

DTIC Science & Technology

1964-06-01

Introduction 1 2. Climatic controls 2 a. General circulation and air masses 2 b. Migratory pressure systems and fronts 3 (1) Extratropical ...Sea-level pressure and surface airflow, January (map) 2 Fig. 2 Sea-level pressure and surface airflow, July (mop) 2 Fig. 3 Tracks of extratropical ...become weaker and less frequent as those of the invading monsoon become more prevalent. b. MIGRATORY PRESSURE SYSTEMS AND FRONTS (1) Extratropical

Numerical simulations of island effects on airflow and weather during the summer over the island of Oahu

Treesearch

Hiep Van Nguyen; Yie-Leng Chen; Francis Fujioka

2010-01-01

The high-resolution (1.5 km) nonhydrostatic fifth-generation Pennsylvania StateUniversity–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) and an advanced land surface model (LSM) are used to study the island-induced airflow and weather for the island of Oahu, Hawaii, under summer trade wind conditions. Despite Oahu’s relatively small...

Aircraft Survivability: Unmanned Aircraft Systems Survivability. Fall 2008

DTIC Science & Technology

2008-01-01

until June 2005. Upon deactivation, LtCol Matthews became the “Marine JCAT of One” and was assigned to the 4th Marine Aircraft Wing as a drilling ...strain gauges along with high- speed video. Seven tests were accomplished (Figure 5): four with no airflow, and three with 200 knots of airflow across...collection for manned and unmanned systems to support vulnerability testing and analysis. As Figure 7 illustrates, the system uses advanced metrology

Assessment of zero-equation SGS models for simulating indoor environment

NASA Astrophysics Data System (ADS)

Taghinia, Javad; Rahman, Md Mizanur; Tse, Tim K. T.

2016-12-01

The understanding of air-flow in enclosed spaces plays a key role to designing ventilation systems and indoor environment. The computational fluid dynamics aspects dictate that the large eddy simulation (LES) offers a subtle means to analyze complex flows with recirculation and streamline curvature effects, providing more robust and accurate details than those of Reynolds-averaged Navier-Stokes simulations. This work assesses the performance of two zero-equation sub-grid scale models: the Rahman-Agarwal-Siikonen-Taghinia (RAST) model with a single grid-filter and the dynamic Smagorinsky model with grid-filter and test-filter scales. This in turn allows a cross-comparison of the effect of two different LES methods in simulating indoor air-flows with forced and mixed (natural + forced) convection. A better performance against experiments is indicated with the RAST model in wall-bounded non-equilibrium indoor air-flows; this is due to its sensitivity toward both the shear and vorticity parameters.

Mechanical Design of a Performance Test Rig for the Turbine Air-Flow Task (TAFT)

NASA Technical Reports Server (NTRS)

Forbes, John C.; Xenofos, George D.; Farrow, John L.; Tyler, Tom; Williams, Robert; Sargent, Scott; Moharos, Jozsef

2004-01-01

To support development of the Boeing-Rocketdyne RS84 rocket engine, a full-flow, reaction turbine geometry was integrated into the NASA-MSFC turbine air-flow test facility. A mechanical design was generated which minimized the amount of new hardware while incorporating all test and instrumentation requirements. This paper provides details of the mechanical design for this Turbine Air-Flow Task (TAFT) test rig. The mechanical design process utilized for this task included the following basic stages: Conceptual Design. Preliminary Design. Detailed Design. Baseline of Design (including Configuration Control and Drawing Revision). Fabrication. Assembly. During the design process, many lessons were learned that should benefit future test rig design projects. Of primary importance are well-defined requirements early in the design process, a thorough detailed design package, and effective communication with both the customer and the fabrication contractors.

Numerical Investigation of the Turbulent Wind Flow Through Elevated Windbreak

NASA Astrophysics Data System (ADS)

Agarwal, Ashish; Irtaza, Hassan

2018-06-01

Analysis of airflow through elevated windbreaks is presented in this paper. Permeable nets and impermeable film increases considerable wind forces on the windbreaks which is susceptible to damage during high wind. A comprehensive numerical investigation has been carried out to analyze the effects of wind on standalone elevated windbreak clad with various permeable nets and an impermeable film. The variation of airflow behavior around and through permeable nets and airflow behavior around impermeable film were also been investigated. Computational fluid dynamics techniques using Reynolds Averaged Navier-Stokes equations has been used to predict the wind force coefficient and thus wind forces on panels supporting permeable nets and impermeable film for turbulent wind flow. Elevated windbreak panels were analyzed for seven different permeable nets having various solidity ratio, specific permeability and aerodynamic resistant coefficients. The permeable nets were modelled as porous jump media obeying Forchheimer's law and an impermeable film modelled as rigid wall.

A budget of energy transfer in a sustained vocal folds vibration in glottis

NASA Astrophysics Data System (ADS)

Zhang, Lucy; Yang, Jubiao; Krane, Michael

2016-11-01

A set of force and energy balance equations using the control volume approach is derived based on the first principles of physics for a sustained vocal folds vibration in glottis. The control volume analysis is done for compressible airflow in a moving and deforming control volume in the vicinity of the vocal folds. The interaction between laryngeal airflow and vocal folds are successfully simulated using the modified Immersed Finite Element Method (mIFEM), a fully coupled approach to simulate fluid-structure interactions. Detailed mathematical terms are separated out for deeper physical understanding and utilization of mechanical energy is quantified with the derived equation. The results show that majority of energy input is consumed for driving laryngeal airflow, while a smaller portion is for compensating viscous losses in and sustaining the vibration of the vocal folds. We acknowledge the funding support of NIH 2R01DC005642-10A1.

Methane emissions and airflow patterns along longwall faces and through bleeder ventilation systems

PubMed Central

Schatzel, Steven J.; Dougherty, Heather N.

2015-01-01

The National Institute for Occupational Safety and Health (NIOSH) conducted an investigation of longwall face and bleeder ventilation systems using tracer gas experiments and computer network ventilation. The condition of gateroad entries, along with the caved material’s permeability and porosity changes as the longwall face advances, determine the resistance of the airflow pathways within the longwall’s worked-out area of the bleeder system. A series of field evaluations were conducted on a four-panel longwall district. Tracer gas was released at the mouth of the longwall section or on the longwall face and sampled at various locations in the gateroads inby the shield line. Measurements of arrival times and concentrations defined airflow/gas movements for the active/completed panels and the bleeder system, providing real field data to delineate these pathways. Results showed a sustained ability of the bleeder system to ventilate the longwall tailgate corner as the panels retreated. PMID:26925166

Influence of airflow rate and substrate nature on heterogeneous struvite precipitation.

PubMed

Saidou, H; Ben Moussa, S; Ben Amor, M

2009-01-01

In wastewater treatment plants a hard scale consisting of struvite crystals can be formed, in pipes and recirculation pumps, during anaerobic digestion of wastewater. This study was conducted to evaluate the effect of airflow rate and substrate nature on nucleation type, induction period and supersaturation coefficient during struvite precipitation. A crystallization reactor similar to that designed for calcium carbonate precipitation was used. The pH of synthetic wastewater solution was increased by air bubbling. Experimental results indicated that the airflow increased heterogeneous precipitation of struvite. The susceptibility to scale formation was more important on polyamide and polyvinyl chloride than on stainless steel. In all cases, X-ray diffraction and infrared spectroscopy showed that the precipitated solid phase was solely struvite. No difference in crystal morphology was observed. However, at similar experimental conditions, the particle size of struvite was higher for stainless-steel material than that for plastic materials.

Numerical Investigation of the Turbulent Wind Flow Through Elevated Windbreak

NASA Astrophysics Data System (ADS)

Agarwal, Ashish; Irtaza, Hassan

2018-04-01

Analysis of airflow through elevated windbreaks is presented in this paper. Permeable nets and impermeable film increases considerable wind forces on the windbreaks which is susceptible to damage during high wind. A comprehensive numerical investigation has been carried out to analyze the effects of wind on standalone elevated windbreak clad with various permeable nets and an impermeable film. The variation of airflow behavior around and through permeable nets and airflow behavior around impermeable film were also been investigated. Computational fluid dynamics techniques using Reynolds Averaged Navier-Stokes equations has been used to predict the wind force coefficient and thus wind forces on panels supporting permeable nets and impermeable film for turbulent wind flow. Elevated windbreak panels were analyzed for seven different permeable nets having various solidity ratio, specific permeability and aerodynamic resistant coefficients. The permeable nets were modelled as porous jump media obeying Forchheimer's law and an impermeable film modelled as rigid wall.

Examination of a newly developed mobile dry scrubber (DS) for coal mine dust control applications

PubMed Central

Organiscak, J.; Noll, J.; Yantek, D.; Kendall, B.

2017-01-01

The Office of Mine Safety and Health Research of the U.S. National Institute for Occupational Safety and Health (NIOSH OMSHR) conducted laboratory testing of a self-tramming, remotely controlled mobile Dry Scrubber (DS) that J.H. Fletcher and Co. developed under a contract with NIOSH OMSHR to reduce the exposure of miners to airborne dust. The scrubber was found to average greater than 95 percent dust removal efficiency with disposable filters, and 88 and 90 percent, respectively, with optional washable filters in their prewash and post-wash test conditions. Although the washable filters can be reused, washing them generated personal and downstream respirable dust concentrations of 1.2 and 8.3 mg/m3, respectively, for a 10-min washing period. The scrubber’s velocity-pressure-regulated variable-frequency-drive fan maintained relatively consistent airflow near the targeted 1.42 and 4.25 m3/s (3,000 and 9,000 ft3/min) airflow rates during most of the laboratory dust testing until reaching its maximum 60-Hz fan motor frequency or horsepower rating at 2,610 Pa (10.5 in. w.g.) of filter differential pressure and 3.97 m3/s (8,420 ft3/min) of scrubber airflow quantity. Laboratory sound level measurements of the scrubber showed that the outlet side of the scrubber was noisier, and the loaded filters increased sound levels compared with clean filters at the same airflow quantities. With loaded filters, the scrubber reached a 90 dB(A) sound level at 2.83 m3/s (6,000 ft3/min) of scrubber airflow, indicating that miners should not be overexposed in relation to MSHA’s permissible exposure level — under Title 30 Code of Federal Regulations Part 62.101— of 90 dB(A) at or below this airflow quantity. The scrubber’s washable filters were not used during field-testing because of their lower respirable dust removal efficiency and the airborne dust generated by filter washing. Field-testing the scrubber with disposable filters at two underground coal mine sections showed that it could clean a portion of the section return air and provide dust reduction of about 50 percent at the face area downstream of the continuous-miner operation. PMID:28596699

Payload bay atmospheric vent airflow testing at the Vibration and Acoustic Test Facility

NASA Technical Reports Server (NTRS)

Johnston, James D., Jr.

1988-01-01

Several concerns related to venting the Space Shuttle Orbiter payload bay during launch led to laboratory experiments with a flight-type vent box installed in the wall of a subsonic wind tunnel. This report describes the test setups and procedures used to acquire data for characterization of airflow through the vent box and acoustic tones radiated from the vent-box cavity. A flexible boundary-layer spoiler which reduced the vent-tone amplitude is described.

Numerical Simulation of Airway Dimension Effects on Airflow Patterns and Odorant Deposition Patterns in the Rat Nasal Cavity

PubMed Central

Wei, Zehong; Xu, Zhixiang; Li, Bo; Xu, Fuqiang

2013-01-01

The sense of smell is largely dependent on the airflow and odorant transport in the nasal cavity, which in turn depends on the anatomical structure of the nose. In order to evaluate the effect of airway dimension on rat nasal airflow patterns and odorant deposition patterns, we constructed two 3-dimensional, anatomically accurate models of the left nasal cavity of a Sprague-Dawley rat: one was based on high-resolution MRI images with relatively narrow airways and the other was based on artificially-widening airways of the MRI images by referencing the section images with relatively wide airways. Airflow and odorant transport, in the two models, were determined using the method of computational fluid dynamics with finite volume method. The results demonstrated that an increase of 34 µm in nasal airway dimension significantly decreased the average velocity in the whole nasal cavity by about 10% and in the olfactory region by about 12% and increased the volumetric flow into the olfactory region by about 3%. Odorant deposition was affected to a larger extent, especially in the olfactory region, where the maximum odorant deposition difference reached one order of magnitude. The results suggest that a more accurate nasal cavity model is necessary in order to more precisely study the olfactory function of the nose when using the rat. PMID:24204875

Sea level static calibration of a compact multimission aircraft propulsion simulator with inlet flow distortion

NASA Technical Reports Server (NTRS)

Won, Mark J.

1990-01-01

Wind tunnel tests of propulsion-integrated aircraft models have identified inlet flow distortion as a major source of compressor airflow measurement error in turbine-powered propulsion simulators. Consequently, two Compact Multimission Aircraft Propulsion Simulator (CMAPS) units were statically tested at sea level ambient conditions to establish simulator operating performance characteristics and to calibrate the compressor airflow against an accurate bellmouth flowmeter in the presence of inlet flow distortions. The distortions were generated using various-shaped wire mesh screens placed upstream of the compressor. CMAPS operating maps and performance envelopes were obtained for inlet total pressure distortions (ratio of the difference between the maximum and minimum total pressures to the average total pressure) up to 35 percent, and were compared to baseline simulator operating characteristics for a uniform inlet. Deviations from CMAPS baseline performance were attributed to the coupled variation of both compressor inlet-flow distortion and Reynolds number index throughout the simulator operating envelope for each screen configuration. Four independent methods were used to determine CMAPS compressor airflow; direct compressor inlet and discharge measurements, an entering/exiting flow-balance relationships, and a correlation between the mixer pressure and the corrected compressor airflow. Of the four methods, the last yielded the least scatter in the compressor flow coefficient, approximately + or - 3 percent over the range of flow distortions.

Use of residence time distribution for evaluation of gaseous pollutant volatilization from stored swine manure.

PubMed

Liao, C M

1997-01-01

A quantification analysis for evaluation of gaseous pollutant volatilization as a result of mass transfer from stored swine manure is presented from the viewpoint of residence time distribution. The method is based on evaluating the moments of concentration vs. time curves of both air and gaseous pollutants. The concept of moments of concentration histories is applicable to characterize the dispersal of the supplied air or gaseous pollutant in a ventilated system. The mean age or residence time of airflow can be calculated from an inverse system state matrix [B]-1 of a linear dynamic equation describing the dynamics of gaseous pollutant in a ventilated airspace. The sum elements in an arbitrary row i in matrix [B]-1 is equal to the mean age of airflow in airspace i. The mean age of gaseous pollutant in airspace i can be obtained from the area under the concentration profile divided by the equilibrium concentration reading in that space caused by gaseous pollutant sources. Matrix [B]-1 can also be represented in terms of the inverse local airflow rate matrix ([W]-1), transition probability matrix ([P]), and air volume matrix ([V]) as, [B]-1 = [W]-1[P][V]. Finally the mean age of airflow in a ventilated airspace can be interpreted by the physical characteristics of matrices [W] and [P]. The practical use of the concepts is also applied in a typical pig unit.

The impacts of the axial-to-radial airflow quantity ratio and suction distance on air curtain dust control in a fully mechanized coal face.

PubMed

Wang, Hao; Cheng, Weimin; Sun, Biao; Yu, Haiming; Jin, Hu

2018-03-01

To understand the impacts of the axial-to-radial airflow quantity ratio (denoted as R) and the suction distance (denoted as D s ) on air curtain dust control in a fully mechanized coal face, the 3 down 610 coal face in Jiangzhuang coal mine was numerically simulated in this study. A mathematic model was established to describe the airflow migration and dust diffusion in a coal face, and a scaled physical model was constructed. The comparison between simulation results and field measurements validated the model and the parameter settings. Furthermore, the airflow migration and dust diffusion at various R and D s are analyzed using Ansys CFD. The results show that a reduction of R and D s is conducive to the formation of an effective axial dust control air curtain; the dust diffusion distance decreases with the decrease of both R and D s . By analyzing the simulation results, the optimal parameter for air curtain dust control in the 3 down 610 coal face and those faces with similar production conditions is determined as R = 1/9 and D s  = 2 m. Under the optimal parameter condition, the high-concentration dust can be confined in front of the mining driver within a space 5.8 m away from the coal face.

Reducing the ingress of urban noise through natural ventilation openings.

PubMed

Oldham, D J; de Salis, M H; Sharples, S

2004-01-01

For buildings in busy urban areas affected by high levels of road traffic noise the potential to use natural ventilation can be limited by excessive noise entering through ventilation openings. This paper is concerned with techniques to reduce noise ingress into naturally ventilated buildings while minimizing airflow path resistance. A combined experimental and theoretical approach to the interaction of airflow and sound transmission through ventilators for natural ventilation applications is described. A key element of the investigation has been the development of testing facilities capable of measuring the airflow and sound transmission losses for a range of ventilation noise control strategies. It is demonstrated that a combination of sound reduction mechanisms -- one covering low frequency sound and another covering high frequency sound -- is required to attenuate effectively noise from typical urban sources. A method is proposed for quantifying the acoustic performance of different strategies to enable comparisons and informed decisions to be made leading to the possibility of a design methodology for optimizing the ventilation and acoustic performance of different strategies. The need for employing techniques for combating low frequency sound in tandem with techniques for reducing high frequency sound in reducing the ingress of noise from urban sources such as road traffic to acceptable levels is demonstrated. A technique is proposed for enabling the acoustic and airflow performance of apertures for natural ventilation systems to be designed simultaneously.

Reconstruction of sound source signal by analytical passive TR in the environment with airflow

NASA Astrophysics Data System (ADS)

Wei, Long; Li, Min; Yang, Debin; Niu, Feng; Zeng, Wu

2017-03-01

In the acoustic design of air vehicles, the time-domain signals of noise sources on the surface of air vehicles can serve as data support to reveal the noise source generation mechanism, analyze acoustic fatigue, and take measures for noise insulation and reduction. To rapidly reconstruct the time-domain sound source signals in an environment with flow, a method combining the analytical passive time reversal mirror (AP-TR) with a shear flow correction is proposed. In this method, the negative influence of flow on sound wave propagation is suppressed by the shear flow correction, obtaining the corrected acoustic propagation time delay and path. Those corrected time delay and path together with the microphone array signals are then submitted to the AP-TR, reconstructing more accurate sound source signals in the environment with airflow. As an analytical method, AP-TR offers a supplementary way in 3D space to reconstruct the signal of sound source in the environment with airflow instead of the numerical TR. Experiments on the reconstruction of the sound source signals of a pair of loud speakers are conducted in an anechoic wind tunnel with subsonic airflow to validate the effectiveness and priorities of the proposed method. Moreover the comparison by theorem and experiment result between the AP-TR and the time-domain beamforming in reconstructing the sound source signal is also discussed.

Reaerosolization of Fluidized Spores in Ventilation Systems▿

PubMed Central

Krauter, Paula; Biermann, Arthur

2007-01-01

This project examined dry, fluidized spore reaerosolization in a heating, ventilating, and air conditioning duct system. Experiments using spores of Bacillus atrophaeus, a nonpathogenic surrogate for Bacillus anthracis, were conducted to delineate the extent of spore reaerosolization behavior under normal indoor airflow conditions. Short-term (five air-volume exchanges), long-term (up to 21,000 air-volume exchanges), and cycled (on-off) reaerosolization tests were conducted using two common duct materials. Spores were released into the test apparatus in turbulent airflow (Reynolds number, 26,000). After the initial pulse of spores (approximately 1010 to 1011 viable spores) was released, high-efficiency particulate air filters were added to the air intake. Airflow was again used to perturb the spores that had previously deposited onto the duct. Resuspension rates on both steel and plastic duct materials were between 10−3 and 10−5 per second, which decreased to 10 times less than initial rates within 30 min. Pulsed flow caused an initial spike in spore resuspension concentration that rapidly decreased. The resuspension rates were greater than those predicted by resuspension models for contamination in the environment, a result attributed to surface roughness differences. There was no difference between spore reaerosolization from metal and that from plastic duct surfaces over 5 hours of constant airflow. The spores that deposited onto the duct remained a persistent source of contamination over a period of several hours. PMID:17293522

Severity of airflow limitation, co-morbidities and management of chronic obstructive pulmonary disease patients acutely admitted to hospital.

PubMed

Au, L H; Chan, H S

2013-12-01

To assess the disease spectrum, severity of airflow limitation, admission pattern, co-morbidities, and management of patients admitted for acute exacerbations of chronic obstructive pulmonary disease. Case series. An acute regional hospital in Hong Kong. Adult subjects admitted during January 2010 to December 2010 with the principal discharge diagnosis of chronic obstructive pulmonary disease. In all, the records of 253 patients with physician-diagnosed chronic obstructive pulmonary disease were analysed. The majority were old (mean age, 78 years). The median number of admissions per patient for this condition in 2010 was two. About two thirds (64%) had had spirometry at least once. Mean forced expiratory volume in one second predicted was 55%. Almost 90% had moderate-to-very severe airflow limitation by spirometry. Overall, long-acting bronchodilators (beta agonists and/or antimuscarinics) were being prescribed for only 21% of the patients. Most of the patients admitted to hospital for acute exacerbations of chronic obstructive pulmonary disease were old, had multiple co-morbidities, and the majority had moderate-to-severe airflow limitation by spirometry. Almost half of them (around 46%) had two or more admissions in 2010. Adherence to the latest treatment guidelines seemed inadequate, there being a low prescription rate of long-acting bronchodilators. Chronic obstructive pulmonary disease patients warranting emergency admissions are at risk of future exacerbations and mortality. Management by a designated multidisciplinary team is recommended.

A Computational Fluid-Dynamics Assessment of the Improved Performance of Aerodynamic Rain Gauges

NASA Astrophysics Data System (ADS)

Colli, Matteo; Pollock, Michael; Stagnaro, Mattia; Lanza, Luca G.; Dutton, Mark; O'Connell, Enda

2018-02-01

The airflow surrounding any catching-type rain gauge when impacted by wind is deformed by the presence of the gauge body, resulting in the acceleration of wind above the orifice of the gauge, which deflects raindrops and snowflakes away from the collector (the wind-induced undercatch). The method of mounting a gauge with the collector at or below the level of the ground, or the use of windshields to mitigate this effect, is often not practicable. The physical shape of a gauge has a significant impact on its collection efficiency. In this study, we show that appropriate "aerodynamic" shapes are able to reduce the deformation of the airflow, which can reduce undercatch. We have employed computational fluid-dynamic simulations to evaluate the time-averaged airflow realized around "aerodynamic" rain gauge shapes when impacted by wind. Terms of comparison are provided by the results obtained for two standard "conventional" rain gauge shapes. The simulations have been run for different wind speeds and are based on a time-averaged Reynolds-Averaged Navier-Stokes model. The shape of the aerodynamic gauges is shown to have a positive impact on the time-averaged airflow patterns observed around the orifice compared to the conventional shapes. Furthermore, the turbulent air velocity fields for the aerodynamic shapes present "recirculating" structures, which may improve the particle-catching capabilities of the gauge collector.

2013 R&D 100 Award: DNATrax could revolutionize air quality detection and tracking

ScienceCinema

Farquar, George

2018-01-16

A team of LLNL scientists and engineers has developed a safe and versatile material, known as DNA Tagged Reagents for Aerosol Experiments (DNATrax), that can be used to reliably and rapidly diagnose airflow patterns and problems in both indoor and outdoor venues. Until DNATrax particles were developed, no rapid or safe way existed to validate air transport models with realistic particles in the range of 1-10 microns. Successful DNATrax testing was conducted at the Pentagon in November 2012 in conjunction with the Pentagon Force Protection Agency. This study enhanced the team's understanding of indoor ventilation environments created by heating, ventilation and air conditioning (HVAC) systems. DNATrax are particles comprised of sugar and synthetic DNA that serve as a bar code for the particle. The potential for creating unique bar-coded particles is virtually unlimited, thus allowing for simultaneous and repeated releases, which dramatically reduces the costs associated with conducting tests for contaminants. Among the applications for the new material are indoor air quality detection, for homes, offices, ships and airplanes; urban particulate tracking, for subway stations, train stations, and convention centers; environmental release tracking; and oil and gas uses, including fracking, to better track fluid flow.

2013 R&D 100 Award: DNATrax could revolutionize air quality detection and tracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farquar, George

A team of LLNL scientists and engineers has developed a safe and versatile material, known as DNA Tagged Reagents for Aerosol Experiments (DNATrax), that can be used to reliably and rapidly diagnose airflow patterns and problems in both indoor and outdoor venues. Until DNATrax particles were developed, no rapid or safe way existed to validate air transport models with realistic particles in the range of 1-10 microns. Successful DNATrax testing was conducted at the Pentagon in November 2012 in conjunction with the Pentagon Force Protection Agency. This study enhanced the team's understanding of indoor ventilation environments created by heating, ventilationmore » and air conditioning (HVAC) systems. DNATrax are particles comprised of sugar and synthetic DNA that serve as a bar code for the particle. The potential for creating unique bar-coded particles is virtually unlimited, thus allowing for simultaneous and repeated releases, which dramatically reduces the costs associated with conducting tests for contaminants. Among the applications for the new material are indoor air quality detection, for homes, offices, ships and airplanes; urban particulate tracking, for subway stations, train stations, and convention centers; environmental release tracking; and oil and gas uses, including fracking, to better track fluid flow.« less

Breathing life into dinosaurs: tackling challenges of soft-tissue restoration and nasal airflow in extinct species.

PubMed

Bourke, Jason M; Porter, W M Ruger; Ridgely, Ryan C; Lyson, Tyler R; Schachner, Emma R; Bell, Phil R; Witmer, Lawrence M

2014-11-01

The nasal region plays a key role in sensory, thermal, and respiratory physiology, but exploring its evolution is hampered by a lack of preservation of soft-tissue structures in extinct vertebrates. As a test case, we investigated members of the "bony-headed" ornithischian dinosaur clade Pachycephalosauridae (particularly Stegoceras validum) because of their small body size (which mitigated allometric concerns) and their tendency to preserve nasal soft tissues within their hypermineralized skulls. Hypermineralization directly preserved portions of the olfactory turbinates along with an internal nasal ridge that we regard as potentially an osteological correlate for respiratory conchae. Fossil specimens were CT-scanned, and nasal cavities were segmented and restored. Soft-tissue reconstruction of the nasal capsule was functionally tested in a virtual environment using computational fluid dynamics by running air through multiple models differing in nasal soft-tissue conformation: a bony-bounded model (i.e., skull without soft tissue) and then models with soft tissues added, such as a paranasal septum, a scrolled concha, a branched concha, and a model combining the paranasal septum with a concha. Deviations in fluid flow in comparison to a phylogenetically constrained sample of extant diapsids were used as indicators of missing soft tissue. Models that restored aspects of airflow found in extant diapsids, such as appreciable airflow in the olfactory chamber, were judged as more likely. The model with a branched concha produced airflow patterns closest to those of extant diapsids. These results from both paleontological observation and airflow modeling indicate that S. validum and other pachycephalosaurids could have had both olfactory and respiratory conchae. Although respiratory conchae have been linked to endothermy, such conclusions require caution in that our re-evaluation of the reptilian nasal apparatus indicates that respiratory conchae may be more widespread than originally thought, and other functions, such as selective brain temperature regulation, could be important. © 2014 Wiley Periodicals, Inc.

Micro-scale pollution mechanism of dust diffusion in a blasting driving face based on CFD-DEM coupled model.

PubMed

Yu, Haiming; Cheng, Weimin; Xie, Yao; Peng, Huitian

2018-05-23

In order to investigate the diffuse pollution mechanisms of high-concentration dusts in the blasting driving face, the airflow-dust coupled model was constructed based on CFD-DEM coupled model; the diffusion rules of the dusts with different diameters at microscopic scale were analyzed in combination with the field measured results. The simulation results demonstrate that single-exhaust ventilation exhibited more favorable dust suppression performance than single-forced ventilation. Under single-exhaust ventilation condition, the motion trajectories of the dusts with the diameter smaller than 20 μm were close to the airflow streamline and these dusts were mainly distributed near the footway walls; by contrast, under single-forced ventilation condition, the motion trajectories of the dust particles with a diameter range of 20~40 μm were close to the airflow streamlines, and a large number of dusts with the diameter smaller than 20 μm accumulated in the regions 5 m and 17~25 m away from the head-on section. Moreover, under the single-exhaust ventilation, the relationship between dust diameter D and negative-pressured-induced dust emission ratio P can be expressed as P = - 25.03ln(D) + 110.39, and the dust emission ratio was up to 74.36% for 7-μm dusts, and the path-dependent settling behaviors of the dusts mainly occurred around the head-on section; under single-forced ventilation condition, the z value of the dusts with the diameter over 20 μm decreased and the dusts with a diameter smaller than 7 μm are particularly harmful to human health, but their settling ratios were below 22.36%. Graphical abstract The airflow-dust CFD-DEM coupling model was established. The numerical simulation results were verified. The migration laws of airflow field were obtained in a blasting driving face. The diffusion laws of dusts were obtained after blasting.

Airflow resistance and CO2 rebreathing properties of anti-asphyxia pillows designed for epilepsy.

PubMed

Catcheside, Peter G; Mohtar, Aaron A; Reynolds, Karen J

2014-06-01

Seizure related unconscious face-down positioning could contribute to sudden unexpected death in epilepsy via asphyxia. Low airflow resistance lattice foam pillows have been advocated for this group. However, data to support this approach remain lacking, and low airflow resistance per se may not negate asphyxia risk from expired gas rebreathing. This study was designed to compare the airflow resistance and CO2 rebreathing properties of lattice vs conventional pillows. Airflow resistance and inspired CO2 levels during replicate 10 min periods of simulated adult ventilation and CO2 rebreathing were compared between cotton, latex and two lattice pillows designed for use in epilepsy (one commercially available, one prototype). Kaplan-Meier and Cox regression analyses were used to examine the hazard of exceeding 10% inspired CO2 within 10-min of rebreathing. Inspiratory resistance was significantly lower in the commercially available and prototype lattice compared to cotton and latex pillows (mean±SD; 3.2±0.8, 2.6±0.4, 26.1±3.5, 4.6±0.4 cm H2O l(-1)s respectively at 0.2l s(-1)). During simulated rebreathing, inspired CO2 exceeded 10% within 2 min with cotton and latex pillows, compared to an upper asymptote around 8-9% at 10 min with lattice pillows. The hazard of exceeding 10% inspired CO2 was therefore markedly reduced with lattice compared to cotton and latex pillows (hazard ratio vs cotton pillow; commercial 0.04 [0.01-0.18], prototype 0.08 [0.02-0.26], latex 0.79 [0.33-1.87]). Conventional pillows can rapidly accumulate potentially life-threatening CO2 levels during simulated rebreathing. Lattice pillows appear to reduce asphyxia risk but accumulated CO2 may still reach levels threatening to health and survival. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Local-Rapid Evaluation of Atmospheric Conditions (L-REAC (trademark)) System, Design and Development. Volume 3. (Operational L-REAC (trademark))

DTIC Science & Technology

2011-09-01

tunnel results show the airflow pattern around a single building. Streamline flow is from left to right. The “canyon flow” is not shown. (Snyder...Agency (EPA)/National Oceanic and Atmospheric Administration (NOAA) wind tunnel results by sampling atmospheric data at strategic locations around a...NOAA wind tunnel results show the airflow pattern around a single building. Streamline flow is from left to right. The “canyon flow” is not shown

Vapor-Generator Wand Helps To Reveal Airflow Patterns

NASA Technical Reports Server (NTRS)

Robelen, David B.

1993-01-01

In vapor-generator wand, liquid propylene glycol flows into electrically heated stainless-steel tube. Liquid boils in heated tube, and emerging vapor forms dense, smoke-like fog used to make airflow patterns visible. Built in variety of sizes, suitable for uses ranging from tabletop demonstrations to research in wind tunnels. For best viewing, plume illuminated by bright, focused incandescent spotlight at right angle to viewing direction. Viewing further enhanced by coating walls of test chamber with flat, dark color to minimize reflections and increase contrast.

Blood Leukocyte Concentrations, FEV1 Decline, and Airflow Limitation. A 15-Year Longitudinal Study of World Trade Center-exposed Firefighters.

PubMed

Zeig-Owens, Rachel; Singh, Ankura; Aldrich, Thomas K; Hall, Charles B; Schwartz, Theresa; Webber, Mayris P; Cohen, Hillel W; Kelly, Kerry J; Nolan, Anna; Prezant, David J; Weiden, Michael D

2018-02-01

Rescue/recovery work at the World Trade Center disaster site (WTC) caused a proximate decline in lung function in Fire Department of the City of New York firefighters. A subset of this cohort experienced an accelerated rate of lung function decline over 15 years of post-September 11, 2001 (9/11) follow-up. To determine if early postexposure blood leukocyte concentrations are biomarkers for subsequent FEV 1 decline and incident airflow limitation. Individual rates of forced expiratory volume in 1 second (FEV 1 ) change were calculated for 9,434 firefighters using 88,709 spirometric measurements taken between September 11, 2001, and September 10, 2016. We categorized FEV 1 change rates into three trajectories: accelerated FEV 1 decline (FEV 1 loss >64 ml/yr), expected FEV 1 decline (FEV 1 loss between 0 and 64 ml/yr), and improved FEV 1 (positive rate of change >0 ml/yr). Occurrence of FEV 1 /FVC less than 0.70 after 9/11 defined incident airflow limitation. Using regression models, we assessed associations of post-9/11 blood eosinophil and neutrophil concentrations with subsequent FEV 1 decline and airflow limitation, adjusted for age, race, smoking, height, WTC exposure level, weight change, and baseline lung function. Accelerated FEV 1 decline occurred in 12.7% of participants (1,199 of 9,434), whereas post-9/11 FEV 1 improvement occurred in 8.3% (780 of 9,434). Higher blood eosinophil and neutrophil concentrations were each associated with accelerated FEV 1 decline after adjustment for covariates (odds ratio [OR], 1.10 per 100 eosinophils/μl; 95% confidence interval [CI], 1.05-1.15; and OR, 1.10 per 1,000 neutrophils/μl; 95% CI, 1.05-1.15, respectively). Multivariable-adjusted linear regression models showed that a higher blood neutrophil concentration was associated with a faster rate of FEV 1 decline (1.14 ml/yr decline per 1,000 neutrophils/μl; 95% CI, 0.69-1.60 ml/yr; P < 0.001). Higher blood eosinophil concentrations were associated with a faster rate of FEV 1 decline in ever-smokers (1.46 ml/yr decline per 100 eosinophils/μl; 95% CI, 0.65-2.26 ml/yr; P < 0.001) but not in never-smokers (P for interaction = 0.004). Higher eosinophil concentrations were also associated with incident airflow limitation (adjusted hazard ratio, 1.10 per 100 eosinophils/μl; 95% CI, 1.04-1.15). Compared with the expected FEV 1 decline group, individuals experiencing accelerated FEV 1 decline were more likely to have incident airflow limitation (adjusted OR, 4.12; 95% CI, 3.30-5.14). Higher post-9/11 blood neutrophil and eosinophil concentrations were associated with subsequent accelerated FEV 1 decline in WTC-exposed firefighters. Both higher blood eosinophil concentrations and accelerated FEV 1 decline were associated with incident airflow limitation in WTC-exposed firefighters.

Simulation and phases of macroscopic particles in vortex flow

NASA Astrophysics Data System (ADS)

Rice, Heath Eric

Granular materials are an interesting class of media in that they exhibit many disparate characteristics depending on conditions. The same set of particles may behave like a solid, liquid, gas, something in-between, or something completely unique depending on the conditions. Practically speaking, granular materials are used in many aspects of manufacturing, therefore any new information gleaned about them may help refine these techniques. For example, learning of a possible instability may help avoid it in practical application, saving machinery, money, and even personnel. To that end, we intend to simulate a granular medium under tornado-like vortex airflow by varying particle parameters and observing the behaviors that arise. The simulation itself was written in Python from the ground up, starting from the basic simulation equations in Poschel [1]. From there, particle spin, viscous friction, and vertical and tangential airflow were added. The simulations were then run in batches on a local cluster computer, varying the parameters of radius, flow force, density, and friction. Phase plots were created after observing the behaviors of the simulations and the regions and borders were analyzed. Most of the results were as expected: smaller particles behaved more like a gas, larger particles behaved more like a solid, and most intermediate simulations behaved like a liquid. A small subset formed an interesting crossover region in the center, and under moderate forces began to throw a few particles at a time upward from the center in a fountain-like effect. Most borders between regions appeared to agree with analysis, following a parabolic critical rotational velocity at which the parabolic surface of the material dips to the bottom of the mass of particles. The fountain effects seemed to occur at speeds along and slightly faster than this division. [1] Please see thesis for references.

Application of Shark Skin Flow Control Techniques to Airflow

NASA Astrophysics Data System (ADS)

Morris, Jackson Alexander

Due to millions of years of evolution, sharks have evolved to become quick and efficient ocean apex predators. Shark skin is made up of millions of microscopic scales, or denticles, that are approximately 0.2 mm in size. Scales located on the shark's body where separation control is paramount (such as behind the gills or the trailing edge of the pectoral fin) are capable of bristling. These scales are hypothesized to act as a flow control mechanism capable of being passively actuated by reversed flow. It is believed that shark scales are strategically sized to interact with the lower 5% of a boundary layer, where reversed flow occurs at the onset of boundary layer separation. Previous research has shown shark skin to be capable of controlling separation in water. This thesis aims to investigate the same passive flow control techniques in air. To investigate this phenomenon, several sets of microflaps were designed and manufactured with a 3D printer. The microflaps were designed in both 2D (rectangular) and 3D (mirroring shark scale geometry) variants. These microflaps were placed in a low-speed wind tunnel in the lower 5% of the boundary layer. Solid fences and a flat plate diffuser with suction were placed in the tunnel to create different separated flow regions. A hot film probe was used to measure velocity magnitude in the streamwise plane of the separated regions. The results showed that low-speed airflow is capable of bristling objects in the boundary layer. When placed in a region of reverse flow, the microflaps were passively actuated. Microflaps fluctuated between bristled and flat states in reverse flow regions located close to the reattachment zone.

Tooth Surface Comparison after Air Polishing and Rubber Cup: A Scanning Electron Microscopy Study.

PubMed

Camboni, Sara; Donnet, Marcel

2016-03-01

To demonstrate, using microscopic observations, the difference between two well-known oral prophylaxis techniques: polishing paste and air polishing. The observations were performed on human enamel. Enamel samples were obtained from plaque-rich human teeth extracted for orthodontic or clinical purposes. In order to allow a reliable comparison between different applications, each enamel sample was divided into two parts: one underwent air-polishing, whereas polishing paste was applied to the other. AIR-FLOW® Master was selected together with AIR-FLOW® PLUS for the prophylaxis powder application. For the polishing-paste application, several different pastes where used, including Cleanic®, CCS®, Proxyt®, and SuperPolish. A comparative test control was also used by cleaning the enamel with sodium hypochlorite (6%). The enamel treated with AIR-FLOW PLUS showed a similar surface when compared to the control enamel; however, there was complete cleaning down to the tooth microstructure. On the other hand, use of the polishing paste resulted in an enamel surface that appeared abraded and flattened. Moreover, some of the natural irregular enamel surfaces demonstrated some filling in with debris. AIR-FLOW PLUS powder was able to more deeply clean without creating any damage to the enamel, making it suitable for regular cleaning treatments. The polishing pastes were found to abrade the enamel surface, to flatten it, and deposit debris into the microcavities. Both methods having different mechanical effects can therefore be considered as complementary, in that some patients experience a sense of "roughness" following a cleaning. A clinical recommendation for this experience would be to use the air polish first to clean the enamel surface, and follow with a little polishing paste to smooth the surface, if required.

Multivariable Robust Control of a Simulated Hybrid Solid Oxide Fuel Cell Gas Turbine Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, Alex; Banta, Larry; Tucker, David

2010-08-01

This work presents a systematic approach to the multivariable robust control of a hybrid fuel cell gas turbine plant. The hybrid configuration under investigation built by the National Energy Technology Laboratory comprises a physical simulation of a 300kW fuel cell coupled to a 120kW auxiliary power unit single spool gas turbine. The public facility provides for the testing and simulation of different fuel cell models that in turn help identify the key difficulties encountered in the transient operation of such systems. An empirical model of the built facility comprising a simulated fuel cell cathode volume and balance of plant componentsmore » is derived via frequency response data. Through the modulation of various airflow bypass valves within the hybrid configuration, Bode plots are used to derive key input/output interactions in transfer function format. A multivariate system is then built from individual transfer functions, creating a matrix that serves as the nominal plant in an H{sub {infinity}} robust control algorithm. The controller’s main objective is to track and maintain hybrid operational constraints in the fuel cell’s cathode airflow, and the turbo machinery states of temperature and speed, under transient disturbances. This algorithm is then tested on a Simulink/MatLab platform for various perturbations of load and fuel cell heat effluence. As a complementary tool to the aforementioned empirical plant, a nonlinear analytical model faithful to the existing process and instrumentation arrangement is evaluated and designed in the Simulink environment. This parallel task intends to serve as a building block to scalable hybrid configurations that might require a more detailed nonlinear representation for a wide variety of controller schemes and hardware implementations.« less

Some potential errors in the measurement of mercury gas exchange at the soil surface using a dynamic flux chamber.

PubMed

Gillis, A; Miller, D R

2000-10-09

A series of controlled environment experiments were conducted to examine the use of a dynamic flux chamber to measure soil emission and absorption of total gaseous mercury (TGM). Uncertainty about the appropriate airflow rates through the chamber and chamber exposure to ambient wind are shown to be major sources of potential error. Soil surface mercury flux measurements over a range of chamber airflow rates showed a positive linear relationship between flux rates and airflow rate through the chamber. Mercury flux measurements using the chamber in an environmental wind tunnel showed that exposure of the system to ambient winds decreased the measured flux rates by 40% at a wind speed of 1.0 m s(-1) and 90% at a wind speed of 2 m s(-1). Wind tunnel measurements also showed that the chamber footprint was limited to the area of soil inside the chamber and there is little uncertainty of the footprint size in dry soil.

Numerical Modelling of Airflow and Temperature Distribution in a Living Room with Different Heat Exchange Conditions

NASA Astrophysics Data System (ADS)

Gendelis, S.; Jakovičs, A.

2010-01-01

Numerical mathematical modelling of the indoor thermal conditions and of the energy losses for separate rooms is an important part of the analysis of the heat-exchange balance and energy efficiency in buildings. The measurements of heat transfer coefficients for bounding structures, the air-tightness tests and thermographic diagnostics done for a building allow the influence of those factors to be predicted more correctly in developed numerical models. The temperature distribution and airflows in a typical room (along with the heat losses) were calculated for different heater locations and solar radiation (modelled as a heat source) through the window, as well as various pressure differences between the openings in opposite walls. The airflow velocities and indoor temperature, including its gradient, were also analysed as parameters of thermal comfort conditions. The results obtained show that all of the listed factors have an important influence on the formation of thermal comfort conditions and on the heat balance in a room.

Gender recognition from vocal source

NASA Astrophysics Data System (ADS)

Sorokin, V. N.; Makarov, I. S.

2008-07-01

Efficiency of automatic recognition of male and female voices based on solving the inverse problem for glottis area dynamics and for waveform of the glottal airflow volume velocity pulse is studied. The inverse problem is regularized through the use of analytical models of the voice excitation pulse and of the dynamics of the glottis area, as well as the model of one-dimensional glottal airflow. Parameters of these models and spectral parameters of the volume velocity pulse are considered. The following parameters are found to be most promising: the instant of maximum glottis area, the maximum derivative of the area, the slope of the spectrum of the glottal airflow volume velocity pulse, the amplitude ratios of harmonics of this spectrum, and the pitch. On the plane of the first two main components in the space of these parameters, an almost twofold decrease in the classification error relative to that for the pitch alone is attained. The male voice recognition probability is found to be 94.7%, and the female voice recognition probability is 95.9%.

Performance of Compressor of XJ-41-V Turbojet Engine. 4; Performance Analysis Over Range of Compressor Speeds from 5000 to 10,000 RPM

NASA Technical Reports Server (NTRS)

Creagh, John W. R.; Ginsburg, Ambrose

1948-01-01

An investigation of the XJ-41-V turbojet-engine compressor was conducted to determine the performance of the compressor and to obtain fundamental information on the aerodynamic problems associated with large centrifugal-type compressors. The results of the research conducted on the original compressor indicated the compressor would not meet the desired engine-design air-flow requirements because of an air-flow restriction in the vaned collector. The compressor air-flow choking point occurred near the entrance to the vaned-collector passage and was instigated by a poor mass-flow distribution at the vane entrance and from relatively large negative angles of attack of the air stream along the entrance edges of the vanes at the outer passage wall and large positive angles of attack at the inner passage wall. As a result of the analysis, a design change of the vaned collector entrance is recommended for improving the maximum flow capacity of the compressor.

Modeling measured glottal volume velocity waveforms.

PubMed

Verneuil, Andrew; Berry, David A; Kreiman, Jody; Gerratt, Bruce R; Ye, Ming; Berke, Gerald S

2003-02-01

The source-filter theory of speech production describes a glottal energy source (volume velocity waveform) that is filtered by the vocal tract and radiates from the mouth as phonation. The characteristics of the volume velocity waveform, the source that drives phonation, have been estimated, but never directly measured at the glottis. To accomplish this measurement, constant temperature anemometer probes were used in an in vivo canine constant pressure model of phonation. A 3-probe array was positioned supraglottically, and an endoscopic camera was positioned subglottically. Simultaneous recordings of airflow velocity (using anemometry) and glottal area (using stroboscopy) were made in 3 animals. Glottal airflow velocities and areas were combined to produce direct measurements of glottal volume velocity waveforms. The anterior and middle parts of the glottis contributed significantly to the volume velocity waveform, with less contribution from the posterior part of the glottis. The measured volume velocity waveforms were successfully fitted to a well-known laryngeal airflow model. A noninvasive measured volume velocity waveform holds promise for future clinical use.

A study on new method of noninvasive esophageal venous pressure measurement based on the airflow and laser detection technology.

PubMed

Hu, Chenghuan; Huang, Feizhou; Zhang, Rui; Zhu, Shaihong; Nie, Wanpin; Liu, Xunyang; Liu, Yinglong; Li, Peng

2015-01-01

Using optics combined with automatic control and computer real-time image detection technology, a novel noninvasive method of noncontact pressure manometry was developed based on the airflow and laser detection technology in this study. The new esophageal venous pressure measurement system was tested in-vitro experiments. A stable and adjustable pulse stream was produced from a self-developed pump and a laser emitting apparatus could generate optical signals which can be captured by image acquisition and analysis system program. A synchronization system simultaneous measured the changes of air pressure and the deformation of the vein wall to capture the vascular deformation while simultaneously record the current pressure value. The results of this study indicated that the pressure values tested by the new method have good correlation with the actual pressure value in animal experiments. The new method of noninvasive pressure measurement based on the airflow and laser detection technology is accurate, feasible, repeatable and has a good application prospects.

Effects of Retronasal Smelling, Variety and Choice on Appetite and Satiety

NASA Technical Reports Server (NTRS)

Hunter, Jean; Halpern, Bruce; Binsted, K.; Caldwell, Bryan

2014-01-01

Four principal areas were investigated. Nasal Patency: Measure nasal tissue swelling and airflow in BR and compare this to PreBR baseline and PostBR recovery; Ask subjects to self-assess nasal congestion at each test to compare with Astronaut self-assessment. Odorant Identification: Measure subject's ability to recognize odorants obtained from food samples taken from FARU (Flight Analog Research Unit) menu and compare this with recognition of food odors not available on FARU; Compare subject assessed ratings of odorant intensity and food liking with nasal airflow measurements to determine effect of fluid shift on smell ability. Meal Acceptability: Determine the onset and progression of reported 'menu fatigue' during BR; Determine whether decreased nasal airflow or smell ability are factors in 'menu fatigue'. Daily Mood and Health: Record mood changes during study and compare with meal acceptability and smell ability. A change in smell ability is measured by tracking subject perception of 35 odorants from admission to the FARU through to dismissal.

Moisture Risk in Unvented Attics Due to Air Leakage Paths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prahl, D.; Shaffer, M.

2014-11-01

IBACOS completed an initial analysis of moisture damage potential in an unvented attic insulated with closed-cell spray polyurethane foam. To complete this analysis, the research team collected field data, used computational fluid dynamics to quantify the airflow rates through individual airflow (crack) paths, simulated hourly flow rates through the leakage paths with CONTAM software, correlated the CONTAM flow rates with indoor humidity ratios from Building Energy Optimization software, and used Wärme und Feuchte instationär Pro two-dimensional modeling to determine the moisture content of the building materials surrounding the cracks. Given the number of simplifying assumptions and numerical models associated withmore » this analysis, the results indicate that localized damage due to high moisture content of the roof sheathing is possible under very low airflow rates. Reducing the number of assumptions and approximations through field studies and laboratory experiments would be valuable to understand the real-world moisture damage potential in unvented attics.« less

Moisture Risk in Unvented Attics Due to Air Leakage Paths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prahl, D.; Shaffer, M.

2014-11-01

IBACOS completed an initial analysis of moisture damage potential in an unvented attic insulated with closed-cell spray polyurethane foam. To complete this analysis, the research team collected field data, used computational fluid dynamics to quantify the airflow rates through individual airflow (crack) paths, simulated hourly flow rates through the leakage paths with CONTAM software, correlated the CONTAM flow rates with indoor humidity ratios from Building Energy Optimization software, and used Warme und Feuchte instationar Pro two-dimensional modeling to determine the moisture content of the building materials surrounding the cracks. Given the number of simplifying assumptions and numerical models associated withmore » this analysis, the results indicate that localized damage due to high moisture content of the roof sheathing is possible under very low airflow rates. Reducing the number of assumptions and approximations through field studies and laboratory experiments would be valuable to understand the real-world moisture damage potential in unvented attics.« less

Effects of Bel Canto Training on Acoustic and Aerodynamic Characteristics of the Singing Voice.

PubMed

McHenry, Monica A; Evans, Joseph; Powitzky, Eric

2016-03-01

This study was designed to assess the impact of 2 years of operatic training on acoustic and aerodynamic characteristics of the singing voice. This is a longitudinal study. Participants were 21 graduate students and 16 undergraduate students. They completed a variety of tasks, including laryngeal videostroboscopy, audio recording of pitch range, and singing of syllable trains at full voice in chest, passaggio, and head registers. Inspiration, intraoral pressure, airflow, and sound pressure level (SPL) were captured during the syllable productions. Both graduate and undergraduate students significantly increased semitone range and SPL. The contributions to increased SPL were typically increased inspiration, increased airflow, and reduced laryngeal resistance, although there were individual differences. Two graduate students increased SPL without increased airflow and likely used supraglottal strategies to do so. Students demonstrated improvements in both acoustic and aerodynamic components of singing. Increasing SPL primarily through respiratory drive is a healthy strategy and results from intensive training. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Playing a brass instrument after total laryngectomy: a case report.

PubMed

Cavalot, Andrea Luigi; Schindler, Antonio; Juliani, Elsa; Schindler, Oskar; Cortesina, Giorgio

2009-08-01

A brass instrument is a musical instrument in which the tone is produced by vibration of the lips as the player blows into a tubular resonator. The case of a professional brass player who continued his activity after total laryngectomy, with insertion of a voice prosthesis in a tracheoesophageal shunt, is reported. A videoendoscopic and videofluoroscopic study of the patient during brass playing was conducted. A nonvibrating, open neoglottis during brass playing was found on videoendoscopy. Videofluorography revealed an enlarged hypopharynx, a thick neoglottis while playing at lower tone; at higher pitch the tongue base was retracted, the neoglottis was thin and stretched, and the subneoglottic area was extremely enlarged. The case reported shows that the insertion of a voice prosthesis in a tracheoesophageal shunt seems to create a regulating airflow system sufficiently advanced to play a brass instrument, further reducing the disability of laryngeal speakers. Copyright 2009 Wiley Periodicals, Inc.

Editorial Introduction: Fourth Planetary Dunes Workshop Special Issue

NASA Astrophysics Data System (ADS)

Chojnacki, Matthew; Telfer, Matt W.

2017-06-01

The Fourth International Planetary Dunes Workshop: Integrating Models, Remote Sensing, and Field Data was held May 19-22, 2015 in Boise, Idaho (see Final Announcement). More than 60 researchers and students participated in two and a half days of presentations and lively discussion, plus a full day field trip to Bruneau Dunes State Park. The workshop focused on the many landforms and deposits created by the dynamic interactions between granular material and airflow (aeolian processes). These processes are known to occur on several planetary bodies, including Earth, Mars, Titan, Venus, and possibly, cometary surfaces. The overarching purpose of this workshop was to provide a forum for discussion and the exchange of new ideas and approaches to gaining new insights into planetary aeolian processes. Meeting programs, abstracts, and E-Posters are all available at the workshop website (http://www.hou.usra.edu/meetings/dunes2015/)

Association of incidental emphysema with annual lung function decline and future development of airflow limitation

PubMed Central

Koo, Hyeon-Kyoung; Jin, Kwang Nam; Kim, Deog Kyeom; Chung, Hee Soon; Lee, Chang-Hoon

2016-01-01

Objectives Emphysema is one of the prognostic factors for rapid lung function decline in patients with COPD, but the impact of incidentally detected emphysema on population without spirometric abnormalities has not been evaluated. This study aimed to determine whether emphysema detected upon computed tomography (CT) screening would accelerate the rate of lung function decline and influence the possibility of future development of airflow limitation in a population without spirometric abnormalities. Materials and methods Subjects who participated in a routine screening for health checkup and follow-up pulmonary function tests for at least 3 years between 2004 and 2010 were retrospectively enrolled. The percentage of low-attenuation area below −950 Hounsfield units (%LAA−950) was calculated automatically. A calculated value of %LAA−950 that exceeded 10% was defined as emphysema. Adjusted annual lung function decline was analyzed using random-slope, random-intercept mixed linear regression models. Results A total of 628 healthy subjects within the normal range of spriometric values were included. Multivariable analysis showed that the emphysema group exhibited a faster decline in forced vital capacity (−33.9 versus −18.8 mL/year; P=0.02). Emphysema was not associated with the development of airflow limitation during follow-up. Conclusion Incidental emphysema quantified using CT scan was significantly associated with a more rapid decline in forced vital capacity in the population with normative spirometric values. However, an association between emphysema and future development of airflow limitation was not observed. PMID:26893550

Application of a New Spirometric Reference Equation and Its Impact on the Staging of Korean Chronic Obstructive Pulmonary Disease Patients

PubMed Central

Hwang, Yong Il; Kim, Eun Ji; Lee, Chang Youl; Park, Sunghoon; Choi, Jeong Hee; Park, Yong Bum; Jang, Seung Hun; Kim, Cheol Hong; Shin, Tae Rim; Park, Sang Myeon; Kim, Dong-Gyu; Lee, Myung-Goo; Hyun, In-Gyu

2012-01-01

Purpose A new spirometric reference equation was recently developed from the first national chronic obstructive pulmonary disease (COPD) survey in Korea. However, Morris' equation has been preferred for evaluating spirometric values instead. The objective of this study was to evaluate changes in severity staging in Korean COPD patients by adopting the newly developed Korean equation. Materials and Methods We evaluated the spirometric data of 441 COPD patients. The presence of airflow limitation was defined as an observed post-bronchodilator forced expiratory volume in one second/forced vital capacity (FEV1/FVC) less than 0.7, and the severity of airflow limitation was assessed according to GOLD stages. Spirometric values were reassessed using the new Korean equation, Morris' equation and other reference equations. Results The severity of airflow limitation was differently graded in 143 (32.4%) patients after application of the new Korean equation when compared with Morris' equation. All 143 patients were reallocated into more severe stages (49 at mild stage, 65 at moderate stage, and 29 at severe stage were changed to moderate, severe and very severe stages, respectively). Stages according to other reference equations were changed in 18.6-49.4% of the patients. Conclusion These results indicate that equations from different ethnic groups do not sufficiently reflect the airflow limitation of Korean COPD patients. The Korean reference equation should be used for Korean COPD patients in order to administer proper treatment. PMID:22318825

An analysis of heat removal during cryogen spray cooling and effects of simultaneous airflow application.

PubMed

Torres, J H; Tunnell, J W; Pikkula, B M; Anvari, B

2001-01-01

Cryogen spray cooling (CSC) is a method used to protect the epidermis from non-specific thermal injury that may occur as a result of various dermatological laser procedures. However, better understanding of cryogen deposition and skin thermal response to CSC is needed to optimize the technique. Temperature measurements and video imaging were carried out on an epoxy phantom as well as human skin during CSC with and without simultaneous application of airflow which was intended to accelerate cryogen evaporation from the substrate surface. An inverse thermal conduction model was used to estimate heat flux and total heat removed. Lifetime of the cryogen film deposited on the surface of skin and epoxy phantom lasted several hundred milliseconds beyond the spurt, but could be reduced to the spurt duration by application of airflow. Values over 100 J/cm(3) were estimated for volumetric heat removed from the epidermis using CSC. "Film cooling" instead of "evaporative cooling" appears to be the dominant mode of CSC on skin. Estimated values of heat removed from the epidermis suggest that a cryogen spurt as long as 200 milliseconds is required to counteract heat generated by high laser fluences (e.g., in treatment of port wine stains) in patients with high concentration of epidermal melanin. Additional cooling beyond spurt termination can be avoided by simultaneous application of airflow, although it is unclear at the moment if avoiding the additional cooling would be beneficial in the actual clinical situation. Copyright 2001 Wiley-Liss, Inc.

Abnormal lung sounds in patients with asthma during episodes with normal lung function.

PubMed

Schreur, H J; Vanderschoot, J; Zwinderman, A H; Dijkman, J H; Sterk, P J

1994-07-01

Even in patients with clinically stable asthma with normal lung function, the airways are characterized by inflammatory changes, including mucosal swelling. In order to investigate whether lung sounds can distinguish these subjects from normal subjects, we compared lung sound characteristics between eight normal and nine symptom-free subjects with mild asthma. All subjects underwent simultaneous recordings of airflow, lung volume changes, and lung sounds during standardized quiet breathing, and during forced maneuvers. Flow-dependent power spectra were computed using fast Fourier transform. For each spectrum we determined lung sound intensity (LSI), frequencies (Q25%, Q50%, Q75%) wheezing (W), and W%. The results were analyzed by ANOVA. During expiration, LSI was lower in patients with asthma than in healthy controls, in particular at relatively low airflow values. During quiet expiration, Q25% to Q75% were higher in asthmatics than in healthy controls, while the change of Q25% to Q75% with flow was greater in asthmatic than in normal subjects. The W and W% were not different between the subject groups. The results indicate that at given airflows, lung sounds are lower in intensity and higher in pitch in asthmatics as compared with controls. This suggests that the generation and/or transmission of lung sounds in symptom-free patients with stable asthma differ from that in normal subjects, even when lung function is within the normal range. Therefore, airflow standardized phonopneumography might reflect morphologic changes in airways of patients with asthma.

Different histological subtypes of peripheral lung cancer based on emphysema distribution in patients with both airflow limitation and CT-determined emphysema.

PubMed

Shin, Beomsu; Shin, Sumin; Chung, Myung Jin; Lee, Hyun; Koh, Won-Jung; Kim, Hojoong; Park, Hye Yun

2017-02-01

The histological subtypes by peripheral tumor location remain uncharacterized in COPD patients with emphysema. We investigated histologic subtypes of peripheral lung cancers based on the context of heterogeneous emphysema distribution in patients with airflow limitation and CT-determined emphysema. A retrospective, cross-sectional study was conducted using data from 754 patients with airflow limitation and newly-diagnosed primary lung cancers from February 2013 to February 2015. Of these, 230 patients had emphysema, as determined by computed tomography software designed to quantify emphysema. Among the 230 patients, the most common subtype in central lesions (n=84) was squamous cell carcinoma (SCC) (n=64/84, 76%). Adenocarcinoma (ADC) was more frequently observed in peripheral lesions (n=146) than central lesions (58/146 [40%] vs. 4/84 [5%], p<0.001). In peripheral lesions, ADC was more frequently seen in areas without emphysema than emphysema areas (43/74 [58%] vs. 15/72 [21%], p<0.001), while SCC was more frequently found in emphysema areas than areas without emphysema (44/72 [61%] vs. 13/74 [18%], p<0.001). These associations persisted with adjustments for age, sex, smoking status and forced expiratory volume in 1s. In patients with both airflow limitation and CT-determined emphysema, the main histological subtype of peripheral lung cancer was SCC in emphysema areas and ADC in areas without emphysema. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

A Comparison between Temperature-Controlled Laminar Airflow Device and a Room Air-Cleaner in Reducing Exposure to Particles While Asleep

PubMed Central

Spilak, Michal P.; Sigsgaard, Torben; Takai, Hisamitsu; Zhang, Guoqiang

2016-01-01

People spend approximately one third of their life sleeping. Exposure to pollutants in the sleep environment often leads to a variety of adverse health effects, such as development and exacerbation of asthma. Avoiding exposure to these pollutants by providing a sufficient air quality in the sleep environment might be a feasible method to alleviate these health symptoms. We performed full-scale laboratory measurements using a thermal manikin positioned on an experimental bed. Three ventilation settings were tested: with no filtration system operated, use of portable air cleaner and use of a temperature-controlled laminar airflow (TLA) device. The first part of the experiment investigated the air-flow characteristics in the breathing zone. In the second part, particle removal efficiency was estimated. Measured in the breathing zone, the room air cleaner demonstrated high turbulence intensity, high velocity and turbulence diffusivity level, with a particle reduction rate of 52% compared to baseline after 30 minutes. The TLA device delivered a laminar airflow to the breathing zone with a reduction rate of 99.5%. During a periodical duvet lifting mimicking a subject’s movement in bed, the particle concentration was significantly lower with the TLA device compared to the room air cleaner. The TLA device provided a barrier which significantly reduced the introduction of airborne particles into the breathing zone. Further studies should be conducted for the understanding of the transport of resuspended particles between the duvet and the laying body. PMID:27898693

A Comparison between Temperature-Controlled Laminar Airflow Device and a Room Air-Cleaner in Reducing Exposure to Particles While Asleep.

PubMed

Spilak, Michal P; Sigsgaard, Torben; Takai, Hisamitsu; Zhang, Guoqiang

2016-01-01

People spend approximately one third of their life sleeping. Exposure to pollutants in the sleep environment often leads to a variety of adverse health effects, such as development and exacerbation of asthma. Avoiding exposure to these pollutants by providing a sufficient air quality in the sleep environment might be a feasible method to alleviate these health symptoms. We performed full-scale laboratory measurements using a thermal manikin positioned on an experimental bed. Three ventilation settings were tested: with no filtration system operated, use of portable air cleaner and use of a temperature-controlled laminar airflow (TLA) device. The first part of the experiment investigated the air-flow characteristics in the breathing zone. In the second part, particle removal efficiency was estimated. Measured in the breathing zone, the room air cleaner demonstrated high turbulence intensity, high velocity and turbulence diffusivity level, with a particle reduction rate of 52% compared to baseline after 30 minutes. The TLA device delivered a laminar airflow to the breathing zone with a reduction rate of 99.5%. During a periodical duvet lifting mimicking a subject's movement in bed, the particle concentration was significantly lower with the TLA device compared to the room air cleaner. The TLA device provided a barrier which significantly reduced the introduction of airborne particles into the breathing zone. Further studies should be conducted for the understanding of the transport of resuspended particles between the duvet and the laying body.

Evaluation and comparison of nasal airway flow patterns among three subjects from Caucasian, Chinese and Indian ethnic groups using computational fluid dynamics simulation.

PubMed

Zhu, Jian Hua; Lee, Heow Pueh; Lim, Kian Meng; Lee, Shu Jin; Wang, De Yun

2011-01-31

Nasal airflow is one of the most important determinants for nasal physiology. During the long evolution of human beings, different races have developed their own attributes of nasal morphologies which result in variations of nasal airflow patterns and nasal functions. This study evaluated and compared the effects of differences of nasal morphology among three healthy male subjects from Caucasian, Chinese and Indian ethnic groups on nasal airflow patterns using computational fluid dynamics simulation. By examining the anterior nasal airway, the nasal indices and the nostril shapes of the three subjects were found to be similar to nasal cavities of respective ethnic groups. Computed tomography images of these three subjects were obtained to reconstruct 3-dimensional models of nasal cavities. To retain the flow characteristics around the nasal vestibules, a 40 mm-radius semi sphere was assembled around the human face for the prescription of zero ambient gauge pressure. The results show that more airflow tends to pass through the middle passage of the nasal airway in the Caucasian model, and through the inferior portion in the Indian model. The Indian model was found with extremely low flow flux flowing through the olfactory region. The sizes of vortexes near the anterior cavity were found to be correlated with the angles between the upper nasal valve wall and the anterior head of the nasal cavity. Copyright © 2010 Elsevier B.V. All rights reserved.

The effects of emphysema on airway disease: correlations between multi-detector CT and pulmonary function tests in smokers.

PubMed

Yahaba, Misuzu; Kawata, Naoko; Iesato, Ken; Matsuura, Yukiko; Sugiura, Toshihiko; Kasai, Hajime; Sakurai, Yoriko; Terada, Jiro; Sakao, Seiichiro; Tada, Yuji; Tanabe, Nobuhiro; Tatsumi, Koichiro

2014-06-01

Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation caused by emphysema and small airway narrowing. Quantitative evaluation of airway dimensions by multi-detector computed tomography (MDCT) has revealed a correlation between airway dimension and airflow limitation. However, the effect of emphysema on this correlation is unclear. The goal of this study was to determine whether emphysematous changes alter the relationships between airflow limitation and airway dimensions as measured by inspiratory and expiratory MDCT. Ninety-one subjects underwent inspiratory and expiratory MDCT. Images were evaluated for mean airway luminal area (Ai), wall area percentage (WA%) from the third to the fifth generation of three bronchi (B1, B5, B8) in the right lung, and low attenuation volume percent (LAV%). Correlations between each airway index and airflow limitation were determined for each patient and compared between patients with and without evidence of emphysema. In patients without emphysema, Ai and WA% from both the inspiratory and expiratory scans were significantly correlated with FEV1. No correlation was detected in patients with emphysema. In addition, emphysematous COPD patients with GOLD stage 1 or 2 disease had significantly lower changes in B8 Ai than non-emphysematous patients. A significant correlation exists between airway parameters and FEV1 in patients without emphysema. Emphysema may influence airway dimensions even in patients with mild to moderate COPD. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Control of nasal vasculature and airflow resistance in the dog.

PubMed Central

Lung, M A; Phipps, R J; Wang, J C; Widdicombe, J G

1984-01-01

Nasal vascular and airflow resistances have been measured in dogs, simultaneously on both sides separately. Vascular resistance was measured either by constant flow perfusion of the terminal branch of the maxillary artery (which supplies, via the sphenopalatine artery, the nasal septum, most of the turbinates and the nasal sinuses) or by measuring blood flow through this artery, maintained by the dog's own blood pressure. Airflow resistance was assessed by inserting balloon-tipped endotracheal catheters into the back of each nasal cavity via the nasopharynx, and measuring transnasal pressure at constant airflow through each side of the nose simultaneously. Preliminary experiments indicated that there was 5-10% collateral anastomosis between the two sides. Close-arterial injection of drugs showed different patterns of response. Adrenaline, phenylephrine, chlorpheniramine and low doses of prostaglandin F2 alpha increased vascular resistance and lowered airway resistance. Salbutamol, methacholine and histamine lowered vascular resistance and increased airway resistance. Dobutamine decreased airway resistance with a small increase in vascular resistance. Prostaglandins E1, E2 and F2 alpha (high dose) decreased both vascular and airway resistances. Substance P, eledoisin-related peptide and vasoactive intestinal polypeptide lowered vascular resistance with little change in airway resistance. The results are interpreted in terms of possible drug actions on precapillary resistance vessels, sinusoids and venules, and arteriovenous anastomoses. It is concluded that nasal airway resistance cannot be correlated with vascular resistance or blood flow, since the latter has a complex and ill-defined relationship with nasal vascular blood volume. PMID:6204040

Control of nasal vasculature and airflow resistance in the dog.

PubMed

Lung, M A; Phipps, R J; Wang, J C; Widdicombe, J G

1984-04-01

Nasal vascular and airflow resistances have been measured in dogs, simultaneously on both sides separately. Vascular resistance was measured either by constant flow perfusion of the terminal branch of the maxillary artery (which supplies, via the sphenopalatine artery, the nasal septum, most of the turbinates and the nasal sinuses) or by measuring blood flow through this artery, maintained by the dog's own blood pressure. Airflow resistance was assessed by inserting balloon-tipped endotracheal catheters into the back of each nasal cavity via the nasopharynx, and measuring transnasal pressure at constant airflow through each side of the nose simultaneously. Preliminary experiments indicated that there was 5-10% collateral anastomosis between the two sides. Close-arterial injection of drugs showed different patterns of response. Adrenaline, phenylephrine, chlorpheniramine and low doses of prostaglandin F2 alpha increased vascular resistance and lowered airway resistance. Salbutamol, methacholine and histamine lowered vascular resistance and increased airway resistance. Dobutamine decreased airway resistance with a small increase in vascular resistance. Prostaglandins E1, E2 and F2 alpha (high dose) decreased both vascular and airway resistances. Substance P, eledoisin-related peptide and vasoactive intestinal polypeptide lowered vascular resistance with little change in airway resistance. The results are interpreted in terms of possible drug actions on precapillary resistance vessels, sinusoids and venules, and arteriovenous anastomoses. It is concluded that nasal airway resistance cannot be correlated with vascular resistance or blood flow, since the latter has a complex and ill-defined relationship with nasal vascular blood volume.

Clinical Characterization and Treatment Patterns for the Frequent Exacerbator Phenotype in Chronic Obstructive Pulmonary Disease with Severe or Very Severe Airflow Limitation.

PubMed

Blasi, Francesco; Neri, Luca; Centanni, Stefano; Falcone, Franco; Di Maria, Giuseppe

2017-02-01

Chronic obstructive pulmonary disease (COPD) patients experiencing several episodes of acute clinical derangement suffer from increased morbidity, mortality, and accelerated decline in lung function. Nevertheless, the relationship between co-morbidity profile and exacerbation rates in the frequent exacerbator phenotype is poorly characterized, and evidence-based management guidelines are lacking. We sought to evaluate the co-morbidity profile and treatment patterns of "frequent exacerbators" with severe or very severe airflow limitation. We conducted a cross-sectional, multicenter study in 50 Italian hospitals. Pulmonologists abstracted clinical information from medical charts of 743 COPD frequent exacerbators. We evaluated the exacerbation risk and center-related variations in diagnostic testing. One-third of patients (n = 210) underwent a bronchodilator response test, and 163 (22%) received a computerized tomography (CT) scan; 35 had a partial response to bronchodilators, while 119 had a diagnosis of emphysema; 584 (79%) lacked sufficient diagnostic testing for classification. Only 17% of patients did not have any coexistent disease. Cardiovascular conditions were the most frequent co-morbidities. A history of heart failure [odds ratio (OR): 1.89; 95% confidence interval (CI) 1.48-2.3] and affective disorders (OR: 1.66; 95% CI 1.24-2.1) was associated with the frequency of exacerbations. Center membership was strongly associated with exacerbation risk, independent of casemix (variance partition coefficient = 29.6%). Examining the regional variation in health outcomes and health care behavior may help identify the best practices, especially when evidence-based recommendations are lacking and uncertainties surround clinical decision-making.

A Comprehensive Breath Plume Model for Disease Transmission via Expiratory Aerosols

PubMed Central

Halloran, Siobhan K.; Wexler, Anthony S.; Ristenpart, William D.

2012-01-01

The peak in influenza incidence during wintertime in temperate regions represents a longstanding, unresolved scientific question. One hypothesis is that the efficacy of airborne transmission via aerosols is increased at lower humidities and temperatures, conditions that prevail in wintertime. Recent work with a guinea pig model by Lowen et al. indicated that humidity and temperature do modulate airborne influenza virus transmission, and several investigators have interpreted the observed humidity dependence in terms of airborne virus survivability. This interpretation, however, neglects two key observations: the effect of ambient temperature on the viral growth kinetics within the animals, and the strong influence of the background airflow on transmission. Here we provide a comprehensive theoretical framework for assessing the probability of disease transmission via expiratory aerosols between test animals in laboratory conditions. The spread of aerosols emitted from an infected animal is modeled using dispersion theory for a homogeneous turbulent airflow. The concentration and size distribution of the evaporating droplets in the resulting “Gaussian breath plume” are calculated as functions of position, humidity, and temperature. The overall transmission probability is modeled with a combination of the time-dependent viral concentration in the infected animal and the probability of droplet inhalation by the exposed animal downstream. We demonstrate that the breath plume model is broadly consistent with the results of Lowen et al., without invoking airborne virus survivability. The results also suggest that, at least for guinea pigs, variation in viral kinetics within the infected animals is the dominant factor explaining the increased transmission probability observed at lower temperatures. PMID:22615902

Polyvinylidene fluoride film based nasal sensor to monitor human respiration pattern: an initial clinical study.

PubMed

Roopa Manjunatha, G; Rajanna, K; Mahapatra, D Roy; Nayak, M M; Krishnaswamy, Uma Maheswari; Srinivasa, R

2013-12-01

Design and development of a piezoelectric polyvinylidene fluoride (PVDF) thin film based nasal sensor to monitor human respiration pattern (RP) from each nostril simultaneously is presented in this paper. Thin film based PVDF nasal sensor is designed in a cantilever beam configuration. Two cantilevers are mounted on a spectacle frame in such a way that the air flow from each nostril impinges on this sensor causing bending of the cantilever beams. Voltage signal produced due to air flow induced dynamic piezoelectric effect produce a respective RP. A group of 23 healthy awake human subjects are studied. The RP in terms of respiratory rate (RR) and Respiratory air-flow changes/alterations obtained from the developed PVDF nasal sensor are compared with RP obtained from respiratory inductance plethysmograph (RIP) device. The mean RR of the developed nasal sensor (19.65 ± 4.1) and the RIP (19.57 ± 4.1) are found to be almost same (difference not significant, p > 0.05) with the correlation coefficient 0.96, p < 0.0001. It was observed that any change/alterations in the pattern of RIP is followed by same amount of change/alterations in the pattern of PVDF nasal sensor with k = 0.815 indicating strong agreement between the PVDF nasal sensor and RIP respiratory air-flow pattern. The developed sensor is simple in design, non-invasive, patient friendly and hence shows promising routine clinical usage. The preliminary result shows that this new method can have various applications in respiratory monitoring and diagnosis.

Evaluation of polyvinylidene fluoride nasal sensor to assess deviated nasal septum in comparision with peak nasal inspiratory flow measurements.

PubMed

Manjunatha, Roopa G; Rajanna, K; Mahapatra, D Roy; Prakash, Surya

2014-01-01

Deviated nasal septum (DNS) is one of the major causes of nasal obstruction. Polyvinylidene fluoride (PVDF) nasal sensor is the new technique developed to assess the nasal obstruction caused by DNS. This study evaluates the PVDF nasal sensor measurements in comparison with PEAK nasal inspiratory flow (PNIF) measurements and visual analog scale (VAS) of nasal obstruction. Because of piezoelectric property, two PVDF nasal sensors provide output voltage signals corresponding to the right and left nostril when they are subjected to nasal airflow. The peak-to-peak amplitude of the voltage signal corresponding to nasal airflow was analyzed to assess the nasal obstruction. PVDF nasal sensor and PNIF were performed on 30 healthy subjects and 30 DNS patients. Receiver operating characteristic was used to analyze the DNS of these two methods. Measurements of PVDF nasal sensor strongly correlated with findings of PNIF (r = 0.67; p < 0.01) in DNS patients. A significant difference (p < 0.001) was observed between PVDF nasal sensor measurements and PNIF measurements of the DNS and the control group. A cutoff between normal and pathological of 0.51 Vp-p for PVDF nasal sensor and 120 L/min for PNIF was calculated. No significant difference in terms of sensitivity of PVDF nasal sensor and PNIF (89.7% versus 82.6%) and specificity (80.5% versus 78.8%) was calculated. The result shows that PVDF measurements closely agree with PNIF findings. Developed PVDF nasal sensor is an objective method that is simple, inexpensive, fast, and portable for determining DNS in clinical practice.

Use of temperature-controlled laminar airflow in the management of atopic asthma: clinical evidence and experience.

PubMed

Warner, John O

2017-04-01

Avoidance of allergens in the treatment of asthma has hitherto not achieved significant benefit despite the strong evidence that allergy both increases severity and contributes to exacerbations of asthma. House dust mite, cat and dog allergens are the most common perennial allergic triggers and most avoidance strategies have focused on reducing exposures in bedrooms. Cochrane reviews have suggested that they neither significantly reduce allergen levels nor improve asthma. While the lack of efficacy may be assumed to be a consequence of exposures occurring outside the bedroom, prolonged sleep is associated with increased susceptibility to bronchospasm and airway inflammation. Thus, if efficient reductions in allergen exposure could be achieved during sleep, it might be expected that this would result in significant improvements in control of asthma. The temperature-controlled laminar airflow (TLA) is a system which can be employed over beds in a domestic environment and results in massive reductions in particulate exposure of recumbent subjects, including highly respirable allergens such as Fel. D1 from cats. Trials of TLA have demonstrated highly significant improvements in asthma quality of life and reductions on airway inflammation as monitored by exhaled nitric oxide levels. Furthermore, in patients with the worst disease, severe exacerbation frequency was significantly reduced. Based on UK health-service costs, the use of TLA falls well below the National Institute for Health and Care Excellence (NICE) threshold for the incremental cost effectiveness ratio (ICER) per quality adjusted life year (QALY). Indeed, for those with frequent exacerbations, it is cost saving and should be prescribed for such allergic asthmatic patients.

Pretreatment Prediction of the Outcomes of Intranasal Steroid Sprays in Cases with Inferior Turbinate Hypertrophy.

PubMed

Karataş, Abdullah

2017-09-01

Intranasal steroid sprays (INSS) are frequently prescribed for treating inferior turbinate hypertrophy (ITH). Complications due to the long-term application of INSS such as crusting, epistaxis, nasal mucosa dryness, and septal perforation may occur. Predicting patients who would benefit from INSS early might lower treatment costs and complication rates. We examined the predictive value of nasal decongestant response rates for the outcomes of INSS in ITH. Fifty patients with bilateral ITH were included in two groups: patients benefiting from INSS and those not benefiting. Nasal airflow was assessed by peak nasal inspiratory flow (PNIF) measurement in all cases. Measurements were taken three times: before and after the application of nasal decongestant sprays and after the application of INSS. In both groups, the nasal air flow rates significantly increased after the application of nasal decongestant sprays; however, the nasal decongestant response rates were higher in the group with patients benefiting from INSS. There was a strong correlation between the nasal air flow rates measured after the application of nasal decongestant sprays and after the application of INSS. The cut-off value for the relationship between increased nasal air flow rates after the application of nasal decongestant sprays and outcomes of INSS was 23%. Measurement of nasal airflow increase rate after the application of nasal decongestant sprays is a simple and easy method for the early prediction of the outcomes of INSS in ITH. A higher than 23% increase in nasal air flow rates after the application of nasal decongestant sprays indicates much better outcomes of INSS for patients.

Pretreatment Prediction of the Outcomes of Intranasal Steroid Sprays in Cases with Inferior Turbinate Hypertrophy

PubMed Central

Karataş, Abdullah

2017-01-01

Objective Intranasal steroid sprays (INSS) are frequently prescribed for treating inferior turbinate hypertrophy (ITH). Complications due to the long-term application of INSS such as crusting, epistaxis, nasal mucosa dryness, and septal perforation may occur. Predicting patients who would benefit from INSS early might lower treatment costs and complication rates. We examined the predictive value of nasal decongestant response rates for the outcomes of INSS in ITH. Methods Fifty patients with bilateral ITH were included in two groups: patients benefiting from INSS and those not benefiting. Nasal airflow was assessed by peak nasal inspiratory flow (PNIF) measurement in all cases. Measurements were taken three times: before and after the application of nasal decongestant sprays and after the application of INSS. Results In both groups, the nasal air flow rates significantly increased after the application of nasal decongestant sprays; however, the nasal decongestant response rates were higher in the group with patients benefiting from INSS. There was a strong correlation between the nasal air flow rates measured after the application of nasal decongestant sprays and after the application of INSS. The cut-off value for the relationship between increased nasal air flow rates after the application of nasal decongestant sprays and outcomes of INSS was 23%. Conclusion Measurement of nasal airflow increase rate after the application of nasal decongestant sprays is a simple and easy method for the early prediction of the outcomes of INSS in ITH. A higher than 23% increase in nasal air flow rates after the application of nasal decongestant sprays indicates much better outcomes of INSS for patients. PMID:29392066

Use of temperature-controlled laminar airflow in the management of atopic asthma: clinical evidence and experience

PubMed Central

Warner, John O.

2017-01-01

Avoidance of allergens in the treatment of asthma has hitherto not achieved significant benefit despite the strong evidence that allergy both increases severity and contributes to exacerbations of asthma. House dust mite, cat and dog allergens are the most common perennial allergic triggers and most avoidance strategies have focused on reducing exposures in bedrooms. Cochrane reviews have suggested that they neither significantly reduce allergen levels nor improve asthma. While the lack of efficacy may be assumed to be a consequence of exposures occurring outside the bedroom, prolonged sleep is associated with increased susceptibility to bronchospasm and airway inflammation. Thus, if efficient reductions in allergen exposure could be achieved during sleep, it might be expected that this would result in significant improvements in control of asthma. The temperature-controlled laminar airflow (TLA) is a system which can be employed over beds in a domestic environment and results in massive reductions in particulate exposure of recumbent subjects, including highly respirable allergens such as Fel. D1 from cats. Trials of TLA have demonstrated highly significant improvements in asthma quality of life and reductions on airway inflammation as monitored by exhaled nitric oxide levels. Furthermore, in patients with the worst disease, severe exacerbation frequency was significantly reduced. Based on UK health-service costs, the use of TLA falls well below the National Institute for Health and Care Excellence (NICE) threshold for the incremental cost effectiveness ratio (ICER) per quality adjusted life year (QALY). Indeed, for those with frequent exacerbations, it is cost saving and should be prescribed for such allergic asthmatic patients. PMID:28391760

Dynamics of near-surface electric discharges and mechanisms of their interaction with the airflow

NASA Astrophysics Data System (ADS)

Leonov, Sergey B.; Adamovich, Igor V.; Soloviev, Victor R.

2016-12-01

The main focus of the review is on dynamics and kinetics of near-surface discharge plasmas, such as surface dielectric barrier discharges sustained by AC and repetitively pulsed waveforms, pulsed DC discharges, and quasi-DC discharges, generated in quiescent air and in the airflow. A number of technical issues related to plasma flow control applications are discussed in detail, including discharge development via surface ionization waves, charge transport and accumulation on dielectric surface, discharge contraction, different types of flow perturbations generated by surface discharges, and effect of high-speed flow on discharge dynamics. In the first part of the manuscript, plasma morphology and results of electrical and optical emission spectroscopy measurements are discussed. Particular attention is paid to dynamics of surface charge accumulation and dissipation, both in diffuse discharges and during development of ionization instabilities resulting in discharge contraction. Contraction leads to significant increase of both the surface area of charge accumulation and the energy coupled to the plasma. The use of alternating polarity pulse waveforms accelerates contraction of surface dielectric barrier discharges and formation of filamentary plasmas. The second part discusses the interaction of discharge plasmas with quiescent air and the external airflow. Four major types of flow perturbations have been identified: (1) low-speed near-surface jets generated by electrohydrodynamic interaction (ion wind); (2) spanwise and streamwise vortices formed by both electrohydrodynamic and thermal effects; (3) weak shock waves produced by rapid heating in pulsed discharges on sub-microsecond time scale; and (4) near-surface localized stochastic perturbations, on sub-millisecond time, detected only recently. The mechanism of plasma-flow interaction remains not fully understood, especially in filamentary surface dielectric barrier discharges. Localized quasi-DC surface discharges sustained in a high-speed flow are discussed in the third part of the review. Although dynamics of this type of the discharge is highly transient, due to its strong interaction with the flow, the resultant flow structure is stationary, including the oblique shock and the flow separation region downstream of the discharge. The oblique shock is attached to a time-averaged, wedge-shaped, near-wall plasma layer, with the shock angle controlled by the discharge power, which makes possible changing the flow structure and parameters in a controlled way. Finally, unresolved and open-ended issues are discussed in the summary.

Uncertainty associated with the gravimetric measurement of particulate matter concentration in ambient air.

PubMed

Lacey, Ronald E; Faulkner, William Brock

2015-07-01

This work applied a propagation of uncertainty method to typical total suspended particulate (TSP) sampling apparatus in order to estimate the overall measurement uncertainty. The objectives of this study were to estimate the uncertainty for three TSP samplers, develop an uncertainty budget, and determine the sensitivity of the total uncertainty to environmental parameters. The samplers evaluated were the TAMU High Volume TSP Sampler at a nominal volumetric flow rate of 1.42 m3 min(-1) (50 CFM), the TAMU Low Volume TSP Sampler at a nominal volumetric flow rate of 17 L min(-1) (0.6 CFM) and the EPA TSP Sampler at the nominal volumetric flow rates of 1.1 and 1.7 m3 min(-1) (39 and 60 CFM). Under nominal operating conditions the overall measurement uncertainty was found to vary from 6.1x10(-6) g m(-3) to 18.0x10(-6) g m(-3), which represented an uncertainty of 1.7% to 5.2% of the measurement. Analysis of the uncertainty budget determined that three of the instrument parameters contributed significantly to the overall uncertainty: the uncertainty in the pressure drop measurement across the orifice meter during both calibration and testing and the uncertainty of the airflow standard used during calibration of the orifice meter. Five environmental parameters occurring during field measurements were considered for their effect on overall uncertainty: ambient TSP concentration, volumetric airflow rate, ambient temperature, ambient pressure, and ambient relative humidity. Of these, only ambient TSP concentration and volumetric airflow rate were found to have a strong effect on the overall uncertainty. The technique described in this paper can be applied to other measurement systems and is especially useful where there are no methods available to generate these values empirically. This work addresses measurement uncertainty of TSP samplers used in ambient conditions. Estimation of uncertainty in gravimetric measurements is of particular interest, since as ambient particulate matter (PM) concentrations approach regulatory limits, the uncertainty of the measurement is essential in determining the sample size and the probability of type II errors in hypothesis testing. This is an important factor in determining if ambient PM concentrations exceed regulatory limits. The technique described in this paper can be applied to other measurement systems and is especially useful where there are no methods available to generate these values empirically.

Coherent tropical-subtropical Holocene see-saw moisture patterns in the Eastern Hemisphere monsoon systems

NASA Astrophysics Data System (ADS)

Wang, Yongbo; Bekeschus, Benjamin; Handorf, Dörthe; Liu, Xingqi; Dallmeyer, Anne; Herzschuh, Ulrike

2017-08-01

The concept of a Global Monsoon (GM) has been proposed based on modern precipitation observations, but its application over a wide range of temporal scales is still under debate. Here, we present a synthesis of 268 continental paleo-moisture records collected from monsoonal systems in the Eastern Hemisphere, including the East Asian Monsoon (EAsM), the Indian Monsoon (IM), the East African Monsoon (EAfM), and the Australian Monsoon (AuM) covering the last 18,000 years. The overall pattern of late Glacial to Holocene moisture change is consistent with those inferred from ice cores and marine records. With respect to the last 10,000 years (10 ka), i.e. a period that has high spatial coverage, a Fuzzy c-Means clustering analysis of the moisture index records together with ;Xie-Beni; index reveals four clusters of our data set. The paleoclimatic meaning of each cluster is interpreted considering the temporal evolution and spatial distribution patterns. The major trend in the tropical AuM, EAfM, and IM regions is a gradual decrease in moisture conditions since the early Holocene. Moisture changes in the EAsM regions show maximum index values between 8 and 6 ka. However, records located in nearby subtropical areas, i.e. in regions not influenced by the intertropical convergence zone, show an opposite trend compared to the tropical monsoon regions (AuM, EAfM and IM), i.e. a gradual increase. Analyses of modern meteorological data reveal the same spatial patterns as in the paleoclimate records such that, in times of overall monsoon strengthening, lower precipitation rates are observed in the nearby subtropical areas. We explain this pattern as the effect of a strong monsoon circulation suppressing air uplift in nearby subtropical areas, and hence hindering precipitation. By analogy to the modern system, this would mean that during the early Holocene strong monsoon period, the intensified ascending airflows within the monsoon domains led to relatively weaker ascending or even descending airflows in the adjacent subtropical regions, resulting in a precipitation deficit compared to the late Holocene. Our conceptual model therefore integrates regionally contrasting moisture changes into the Global Monsoon hypothesis.

Relation of pulmonary vessel size to transfer factor in subjects with airflow obstruction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musk, A.W.

In a group of 61 consecutive patients undergoing assessment of airflow obstruction, a significant linear relation was demonstrated between measurements of the diameter of the midzonal pulmonary vessels on the plain chest radiographs and transfer factor (diffusing capacity for carbon monoxide) (r = 0.46, p < 0.001). Since reduction in transfer factor has been shown to relate to structural emphysema, reduction in midzone vessel caliber implies the same. However, in the individual patient neither the transfer factor nor structural emphysema can be reliably predicted from midzone vessel diameters alone.

Spacecraft Minimum Allowable Concentrations: Determination, Application, and Contingency Situations

NASA Technical Reports Server (NTRS)

Marshburn, Thomas H.; Dawson, David L. (Technical Monitor)

1999-01-01

This document is an outline of a presentation about the determination of minimum allowable concentrations in spacecraft. The presentation reviews the type of toxins and mechanisms to determine the acceptable concentrations of these toxic substances. The considerations for the unique situation that spaceflight entails including zero gravity, and the intense scrutiny are reviewed. The current measurement hardware is reviewed. The spacecraft atmospheres on the Shuttle, airflow, the Space Station and the EMU in respect to airflow, pressure, constituents are also summarized. Contingency situations and potential hazards are also discussed.

Riblets for Stars and Stripes

NASA Astrophysics Data System (ADS)

1987-01-01

Stars and Stripes racing yacht brought the American's Cup back to the United States. Originating from NASA's drag reduction technology, the boats "secret weapon" was that the hull's underside was coated with riblets. Riblets are small, barely visible grooves on the surface of an airplane intended to reduce skin friction by smoothing the turbulent airflow next to the skin. Grooves are V-shaped with the angle pointing in the direction of the airflow. No deeper than a scratch, they have a pronounced beneficial influence on air turbulence. *No longer commercially available.

Clinical Issues-November 2017.

PubMed

Johnstone, Esther M

2017-11-01

Heating, ventilation, and air-conditioning (HVAC) systems in the OR Key words: airborne contaminants, HVAC system, air pressure, air quality, temperature and humidity. Air changes and positive pressure Key words: air changes, positive pressure airflow, unidirectional airflow, outdoor air, recirculated air. Product selection Key word: product evaluation, product selection, selection committee. Entry into practice Key words: associate degree in nursing, bachelor of science in nursing, entry-level position, advanced education, BSN-prepared RNs. Mentoring in perioperative nursing Key words: mentor, novice, practice improvement, nursing workforce. Copyright © 2017 AORN, Inc. Published by Elsevier Inc. All rights reserved.

Description and test results of a digital supersonic propulsion system integrated control

NASA Technical Reports Server (NTRS)

Batterton, P. G.; Arpasi, D. J.; Baumbick, R. J.

1976-01-01

A digitally implemented integrated inlet/engine control system was developed and tested on a mixed compression, Mach 2.5, supersonic inlet and augmented turbofan engine. The control matched engine airflow to available inlet airflow so that in steady state, the shock would be at the desired location, and the overboard bypass doors would be closed. During engine induced transients, such as augmentor lights and cutoffs, the inlet operating point was momentarily changed to a more supercritical point to minimize unstarts. The digital control also provided automatic inlet restart.

Determinants of airflow obstruction in severe alpha‐1‐antitrypsin deficiency

PubMed Central

DeMeo, Dawn L; Sandhaus, Robert A; Barker, Alan F; Brantly, Mark L; Eden, Edward; McElvaney, N Gerard; Rennard, Stephen; Burchard, Esteban; Stocks, James M; Stoller, James K; Strange, Charlie; Turino, Gerard M; Campbell, Edward J; Silverman, Edwin K

2007-01-01

Background Severe α1‐antitrypsin (AAT) deficiency is an autosomal recessive genetic condition associated with an increased but variable risk for chronic obstructive pulmonary disease (COPD). A study was undertaken to assess the impact of chronic bronchitis, pneumonia, asthma and sex on the development of COPD in individuals with severe AAT deficiency. Methods The AAT Genetic Modifier Study is a multicentre family‐based cohort study designed to study the genetic and epidemiological determinants of COPD in AAT deficiency. 378 individuals (age range 33–80 years), confirmed to be homozygous for the SERPINA1 Z mutation, were included in the analyses. The primary outcomes of interest were a quantitative outcome, forced expiratory volume in 1 s (FEV1) percentage predicted, and a qualitative outcome, severe airflow obstruction (FEV1 <50% predicted). Results In multivariate analysis of the overall cohort, cigarette smoking, sex, asthma, chronic bronchitis and pneumonia were risk factors for reduced FEV1 percentage predicted and severe airflow obstruction (p<0.01). Index cases had lower FEV1 values, higher smoking histories and more reports of adult asthma, pneumonia and asthma before age 16 than non‐index cases (p<0.01). Men had lower pre‐ and post‐bronchodilator FEV1 percentage predicted than women (p<0.0001); the lowest FEV1 values were observed in men reporting a history of childhood asthma (26.9%). This trend for more severe obstruction in men remained when index and non‐index groups were examined separately, with men representing the majority of non‐index individuals with airflow obstruction (71%). Chronic bronchitis (OR 3.8, CI 1.8 to 12.0) and a physician's report of asthma (OR 4.2, CI 1.4 to 13.1) were predictors of severe airflow obstruction in multivariate analysis of non‐index men but not women. Conclusion In individuals with severe AAT deficiency, sex, asthma, chronic bronchitis and pneumonia are risk factors for severe COPD, in addition to cigarette smoking. These results suggest that, in subjects severely deficient in AAT, men, individuals with symptoms of chronic bronchitis and/or a past diagnosis of asthma or pneumonia may benefit from closer monitoring and potentially earlier treatment. PMID:17389752

Atmospheric Boundary Layer Dynamics Near Ross Island and Over West Antarctica.

NASA Astrophysics Data System (ADS)

Liu, Zhong

The atmospheric boundary layer dynamics near Ross Island and over West Antarctica has been investigated. The study consists of two parts. The first part involved the use of data from ground-based remote sensing equipment (sodar and RASS), radiosondes, pilot balloons, automatic weather stations, and NOAA AVHRR satellite imagery. The second part involved the use of a high resolution boundary layer model coupled with a three-dimensional primitive equation mesoscale model to simulate the observed atmospheric boundary layer winds and temperatures. Turbulence parameters were simulated with an E-epsilon turbulence model driven by observed winds and temperatures. The observational analysis, for the first time, revealed that the airflow passing through the Ross Island area is supplied mainly by enhanced katabatic drainage from Byrd Glacier and secondarily drainage from Mulock and Skelton glaciers. The observed diurnal variation of the blocking effect near Ross Island is dominated by the changes in the upstream katabatic airflow. The synthesized analysis over West Antarctica found that the Siple Coast katabatic wind confluence zone consists of two superimposed katabatic airflows: a relatively warm and more buoyant katabatic flow from West Antarctica overlies a colder and less buoyant katabatic airflow from East Antarctica. The force balance analysis revealed that, inside the West Antarctic katabatic wind zone, the pressure gradient force associated with the blocked airflow against the Transantarctic Mountains dominates; inside the East Antarctic katabatic wind zone, the downslope buoyancy force due to the cold air overlying the sloping terrain is dominant. The analysis also shows that these forces are in geostrophic balance with the Coriolis force. An E-epsilon turbulence closure model is used to simulate the diurnal variation of sodar backscatter. The results show that the model is capable of qualitatively capturing the main features of the observed sodar backscatter. To improve the representation of the atmospheric boundary layer, a second-order turbulence closure model coupled with the input from a mesoscale model was applied to the springtime Siple Coast katabatic wind confluence zone. The simulation was able to capture the main features of the confluence zone, which were not well resolved by the mesoscale model.

Using Coupled Energy, Airflow and IAQ Software (TRNSYS/CONTAM) to Evaluate Building Ventilation Strategies.

PubMed

Dols, W Stuart; Emmerich, Steven J; Polidoro, Brian J

2016-03-01

Building energy analysis tools are available in many forms that provide the ability to address a broad spectrum of energy-related issues in various combinations. Often these tools operate in isolation from one another, making it difficult to evaluate the interactions between related phenomena and interacting systems, forcing oversimplified assumptions to be made about various phenomena that could otherwise be addressed directly with another tool. One example of such interdependence is the interaction between heat transfer, inter-zone airflow and indoor contaminant transport. In order to better address these interdependencies, the National Institute of Standards and Technology (NIST) has developed an updated version of the multi-zone airflow and contaminant transport modelling tool, CONTAM, along with a set of utilities to enable coupling of the full CONTAM model with the TRNSYS simulation tool in a more seamless manner and with additional capabilities that were previously not available. This paper provides an overview of these new capabilities and applies them to simulating a medium-size office building. These simulations address the interaction between whole-building energy, airflow and contaminant transport in evaluating various ventilation strategies including natural and demand-controlled ventilation. CONTAM has been in practical use for many years allowing building designers, as well as IAQ and ventilation system analysts, to simulate the complex interactions between building physical layout and HVAC system configuration in determining building airflow and contaminant transport. It has been widely used to design and analyse smoke management systems and evaluate building performance in response to chemical, biological and radiological events. While CONTAM has been used to address design and performance of buildings implementing energy conserving ventilation systems, e.g., natural and hybrid, this new coupled simulation capability will enable users to apply the tool to couple CONTAM with existing energy analysis software to address the interaction between indoor air quality considerations and energy conservation measures in building design and analysis. This paper presents two practical case studies using the coupled modelling tool to evaluate IAQ performance of a CO 2 -based demand-controlled ventilation system under different levels of building envelope airtightness and the design and analysis of a natural ventilation system.

Using Coupled Energy, Airflow and IAQ Software (TRNSYS/CONTAM) to Evaluate Building Ventilation Strategies

PubMed Central

Dols, W. Stuart.; Emmerich, Steven J.; Polidoro, Brian J.

2016-01-01

Building energy analysis tools are available in many forms that provide the ability to address a broad spectrum of energy-related issues in various combinations. Often these tools operate in isolation from one another, making it difficult to evaluate the interactions between related phenomena and interacting systems, forcing oversimplified assumptions to be made about various phenomena that could otherwise be addressed directly with another tool. One example of such interdependence is the interaction between heat transfer, inter-zone airflow and indoor contaminant transport. In order to better address these interdependencies, the National Institute of Standards and Technology (NIST) has developed an updated version of the multi-zone airflow and contaminant transport modelling tool, CONTAM, along with a set of utilities to enable coupling of the full CONTAM model with the TRNSYS simulation tool in a more seamless manner and with additional capabilities that were previously not available. This paper provides an overview of these new capabilities and applies them to simulating a medium-size office building. These simulations address the interaction between whole-building energy, airflow and contaminant transport in evaluating various ventilation strategies including natural and demand-controlled ventilation. Practical Application CONTAM has been in practical use for many years allowing building designers, as well as IAQ and ventilation system analysts, to simulate the complex interactions between building physical layout and HVAC system configuration in determining building airflow and contaminant transport. It has been widely used to design and analyse smoke management systems and evaluate building performance in response to chemical, biological and radiological events. While CONTAM has been used to address design and performance of buildings implementing energy conserving ventilation systems, e.g., natural and hybrid, this new coupled simulation capability will enable users to apply the tool to couple CONTAM with existing energy analysis software to address the interaction between indoor air quality considerations and energy conservation measures in building design and analysis. This paper presents two practical case studies using the coupled modelling tool to evaluate IAQ performance of a CO2-based demand-controlled ventilation system under different levels of building envelope airtightness and the design and analysis of a natural ventilation system. PMID:27099405

Bayesian Modeling of Exposure and Airflow Using Two-Zone Models

PubMed Central

Zhang, Yufen; Banerjee, Sudipto; Yang, Rui; Lungu, Claudiu; Ramachandran, Gurumurthy

2009-01-01

Mathematical modeling is being increasingly used as a means for assessing occupational exposures. However, predicting exposure in real settings is constrained by lack of quantitative knowledge of exposure determinants. Validation of models in occupational settings is, therefore, a challenge. Not only do the model parameters need to be known, the models also need to predict the output with some degree of accuracy. In this paper, a Bayesian statistical framework is used for estimating model parameters and exposure concentrations for a two-zone model. The model predicts concentrations in a zone near the source and far away from the source as functions of the toluene generation rate, air ventilation rate through the chamber, and the airflow between near and far fields. The framework combines prior or expert information on the physical model along with the observed data. The framework is applied to simulated data as well as data obtained from the experiments conducted in a chamber. Toluene vapors are generated from a source under different conditions of airflow direction, the presence of a mannequin, and simulated body heat of the mannequin. The Bayesian framework accounts for uncertainty in measurement as well as in the unknown rate of airflow between the near and far fields. The results show that estimates of the interzonal airflow are always close to the estimated equilibrium solutions, which implies that the method works efficiently. The predictions of near-field concentration for both the simulated and real data show nice concordance with the true values, indicating that the two-zone model assumptions agree with the reality to a large extent and the model is suitable for predicting the contaminant concentration. Comparison of the estimated model and its margin of error with the experimental data thus enables validation of the physical model assumptions. The approach illustrates how exposure models and information on model parameters together with the knowledge of uncertainty and variability in these quantities can be used to not only provide better estimates of model outputs but also model parameters. PMID:19403840

Grading Severity of Productive Cough Based on Symptoms and Airflow Obstruction.

PubMed

Vazquez Guillamet, Rodrigo; Petersen, Hans; Meek, Paula; Sood, Akshay; Tesfaigzi, Yohannes

2018-04-26

The binary approach to the diagnosis of Chronic Bronchitis (CB) is a major barrier to the study of the disease. We investigated whether severity of productive cough can be graded using symptoms and presence of fixed airflow obstruction (FAO), and whether the severity correlates with health status, exposures injurious to the lung, biomarkers of inflammation, and measures of airway wall thickening. Findings from a cross-sectional sample of 1,422 participants from the Lovelace Smokers Cohort (LSC) were validated in 4,488 participants from the COPDGene cohort (COPDGene). Health status was based on the St. George's Respiratory Questionnaire, and Medical Outcomes Study 36-Item Short Form Health Survey. Circulating CC16 levels were quantified by ELISA (LSC), and airway wall thickening was measured using computed tomography (COPDGene). FAO was defined as postbronchodilator FEV 1 /FVC <0.7. The presence and duration of productive cough and presence of FAO or wheeze were graded into Healthy Smokers, Productive Cough (PC), Chronic PC, PC with Signs of Airflow Obstruction, and Chronic PC with Signs of Airflow Obstruction. In both cohorts, higher grade of severity correlated with lower health status, greater frequency of injurious exposures, greater airway wall thickening, and lower circulating CC16 levels. Further, longitudinal follow-up suggested that disease resolution can occur at every grade of severity but is more common in groups of lower severity and least common once airway remodeling develops. Therefore, severity of productive cough can be graded based on symptoms and FAO and early intervention may benefit patients by changing the natural history of disease.

A novel method for detecting airway narrowing using breath sound spectrum analysis in children.

PubMed

Tabata, Hideyuki; Hirayama, Mariko; Enseki, Mayumi; Nukaga, Mariko; Hirai, Kota; Furuya, Hiroyuki; Mochizuki, Hiroyuki

2016-01-01

Using a breath sound analyzer, we investigated new clinical parameters that are rarely affected by airflow in young children. A total of 65 children with asthma participated in this study (mean age 9.6 years). In Study 1, the intra- and inter-observer variability was measured. Common breath sound parameters, frequency at 99%, 75%, and 50% of the maximum frequency (F99, F75, and F50) and the highest frequency of inspiratory breath sounds were calculated. In addition, new parameters obtained using the ratio of sound spectra parameters, i.e., the spectrum curve indexes including the ratio of the third and fourth area to the total area and the ratio of power and frequency at F75 and F50, were calculated. In Study 2, 51 children underwent breath sound analyses. In Study 3, breath sounds were studied before and after methacholine inhalation. In Study 1, the data showed good inter- and intra-observer reliability. In Study 2, there were significant relationships between the airflow rate, age, height, and spirometric and common breath sound parameters. However, there were no significant relationships between the airflow rate and the spectrum curve indexes. Moreover, the spectrum curve indexes showed no relationships with age, height, or spirometric parameters. In Study 3, all parameters significantly changed after methacholine inhalation. Some spectrum curve indexes are not significantly affected by the airflow rate at the mouth, although they successfully indicate airway narrowing. These parameters may play a role in the assessment of bronchoconstriction in children. Copyright © 2015 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Airflow, gas deposition, and lesion distribution in the nasal passages.

PubMed Central

Morgan, K T; Monticello, T M

1990-01-01

The nasal passages of laboratory animals and man are complex, and lesions induced in the delicate nasal lining by inhaled air pollutants vary considerably in location and nature. The distribution of nasal lesions is generally a consequence of regional deposition of the inhaled material, local tissue susceptibility, or a combination of these factors. Nasal uptake and regional deposition are are influenced by numerous factors including the physical and chemical properties of the inhaled material, such as water solubility and reactivity; airborne concentration and length of exposure; the presence of other air contaminants such as particulate matter; nasal metabolism, and blood and mucus flow. For certain highly water-soluble or reactive gases, nasal airflow patterns play a major role in determining lesion distribution. Studies of nasal airflow in rats and monkeys, using casting and molding techniques combined with a water-dye model, indicate that nasal airflow patterns are responsible for characteristic differences in the distribution of nasal lesions induced by formaldehyde in these species. Local tissue susceptibility is also a complex issue that may be a consequence of many factors, including physiologic and metabolic characteristics of the diverse cell populations that comprise each of the major epithelial types lining the airways. Identification of the principal factors that influence the distribution and nature of nasal lesions is important when attempting the difficult process of determining potential human risks using data derived from laboratory animals. Toxicologic pathologists can contribute to this process by carefully identifying the site and nature of nasal lesions induced by inhaled materials. Images FIGURE 4. FIGURE 6. FIGURE 7. PMID:2200663

Interactions of bluff-body obstacles with turbulent airflows affecting evaporative fluxes from porous surfaces

NASA Astrophysics Data System (ADS)

Haghighi, Erfan; Or, Dani

2015-11-01

Bluff-body obstacles interacting with turbulent airflows are common in many natural and engineering applications (from desert pavement and shrubs over natural surfaces to cylindrical elements in compact heat exchangers). Even with obstacles of simple geometry, their interactions within turbulent airflows result in a complex and unsteady flow field that affects surface drag partitioning and transport of scalars from adjacent evaporating surfaces. Observations of spatio-temporal thermal patterns on evaporating porous surfaces adjacent to bluff-body obstacles depict well-defined and persistent zonation of evaporation rates that were used to construct a simple mechanistic model for surface-turbulence interactions. Results from evaporative drying of sand surfaces with isolated cylindrical elements (bluff bodies) subjected to constant turbulent airflows were in good agreement with model predictions for localized exchange rates. Experimental and theoretical results show persistent enhancement of evaporative fluxes from bluff-rough surfaces relative to smooth flat surfaces under similar conditions. The enhancement is attributed to formation of vortices that induce a thinner boundary layer over part of the interacting surface footprint. For a practical range of air velocities (0.5-4.0 m/s), low-aspect ratio cylindrical bluff elements placed on evaporating sand surfaces enhanced evaporative mass losses (relative to a flat surface) by up to 300% for high density of elements and high wind velocity, similar to observations reported in the literature. Concepts from drag partitioning were used to generalize the model and upscale predictions to evaporation from surfaces with multiple obstacles for potential applications to natural bluff-rough surfaces.

Voluntary Cough Airflow Differentiates Safe versus Unsafe Swallowing in Amyotrophic Lateral Sclerosis

PubMed Central

Plowman, Emily K.; Watts, Stephanie A.; Robison, Raele; Tabor, Lauren; Dion, Charles; Gaziano, Joy; Vu, Tuan; Gooch, Clifton

2016-01-01

Dysphagia and aspiration are prevalent in amyotrophic lateral sclerosis (ALS) and contribute to malnutrition, aspiration pneumonia and death. Early detection of at risk individuals is critical to ensure maintenance of safe oral intake and optimal pulmonary function. We therefore aimed to determine the discriminant ability of voluntary cough airflow measures in detecting penetration/aspiration status in ALS patients. Seventy individuals with ALS (El-Escorial criteria) completed voluntary cough spirometry testing and underwent a standardized videofluoroscopic swallowing evaluation (VFSE). A rater blinded to aspiration status derived six objective measures of voluntary cough airflow and evaluated airway safety using the Penetration Aspiration Scale (PAS). A between groups ANOVA (safe vs. unsafe swallowers) was conducted and sensitivity, specificity, area under the curve (AUC) and likelihood ratios were calculated. VFSE analysis revealed 24 penetrator/aspirators (PAS ≥3) and 46 non-penetrator/aspirators (PAS ≤2). Cough volume acceleration (CVA), peak expiratory flow rise time (PEFRT), and peak expiratory flow rate (PEFR) were significantly different between airway safety groups (p <0.05) and demonstrated significant discriminant ability to detect the presence of penetration/aspiration with AUC values of: 0.85, 0.81, and 0.78 respectively. CVA < 45.28L/s/s, PEFR <3.97L/s, and PEFRT > 76ms had sensitivities of 91.3%, 82.6% and 73.9% respectively and specificities of 82.2%, 73.9%, and 78.3% for identifying ALS penetrator/aspirators. Voluntary cough airflow measures identified ALS patients at risk for penetration/aspiration and may be a valuable screening tool with high clinical utility. PMID:26803772

Effect of enzymatic pretreatment on the physical quality of plantain (Musa ssp., group AAB) employing airflow reversal drying.

PubMed

Rodríguez-Miranda, J; Martínez-Sánchez, C E; Hernández-Santos, B; Juárez-Barrientos, J M; Ventura-Báez, E G; Herman-Lara, E

2018-01-01

This work aimed to evaluate the effect of enzymatic pretreatment on the color and texture of plantain ( Musa ssp., group AAB) dried by airflow reversal drying. Plantain slices 1.0 cm thick were used. Pretreatment with two commercial enzymes, Pectinex Ultra SPL ( Aspergillus aculeatus ) and Pectinex 3XL ( Aspergillus niger ), was performed. Drying kinetics were determined with and without pretreatment at temperatures of 50, 65 and 80 °C using a fixed bed convective dryer. An air speed of 6 m/s, a bed height of 5 cm and either unidirectional flow or airflow reversal (every 15 min) were used for drying. Color and texture were analyzed, and consumer acceptance of the results of the best treatments was determined. Pretreatment with the enzyme A. niger and airflow reversal gave the best drying kinetics and showed the greatest reduction in drying time (59.0%) at 80 °C. The best hardness results were found at 80 °C with A. niger enzymatic pretreatment with both types of air flow. Brightness and hue angle showed that samples pretreated with enzymes and dried at 65 °C had a lighter yellow color compared to non-pretreated samples. Plantain samples enzymatically pretreated and dried at 65 and 80 °C were the most accepted by consumers. This kind of enzymatic pretreatment on plantain could allow the conservation of some physical properties and reduction of drying times relative to the current methodology.

A long slit-like entrance promotes ventilation in the mud nesting social wasp, Polybia spinifex: visualization of nest microclimates using computational fluid dynamics.

PubMed

Hozumi, Satoshi; Inagaki, Terumi

2010-01-01

Polybia spinifex Richards (Hymenoptera: Vespidae) constructs mud nests characterized by a long slit-like entrance. The ventilation and thermal characteristics of the P. spinifex nest were investigated to determine whether the nest microclimate is automatically maintained due to the size of the entrance. In order to examine this hypothesis, a numerical simulation was employed to predict the effects of the entrance length. The calculations were performed with 3D-virtual models that simulated the P. spinifex nest conditions, and the reliability of the simulations was experimentally examined by using gypsum-model nests and a P. spinifex nest. The ventilation effect was determined by blowing air through the nest at 1-3 m/s (airflow conditions); the airspeed was found to be higher in models with a longer entrance. The ventilation rate was also higher in models with longer entrances, suggesting that the P. spinifex nest is automatically ventilated by natural winds. Next, the thermal effect was calculated under condition of direct sunlight. Under a calm condition (airflow, 0 m/s), thermal convection and a small temperature drop were observed in the case of models with a long entrance, whereas the ventilation and thermoregulation effects seemed small. Under airflow conditions, the temperature at the mid combs steeply dropped due to the convective airflow through the entrance at 1-2 m/s, and at 3 m/s, most of the heat was eliminated due to high thermal conductivity of the mud envelope, rather than convection.

Corollary discharge inhibition of wind-sensitive cercal giant interneurons in the singing field cricket

PubMed Central

Hedwig, Berthold

2014-01-01

Crickets carry wind-sensitive mechanoreceptors on their cerci, which, in response to the airflow produced by approaching predators, triggers escape reactions via ascending giant interneurons (GIs). Males also activate their cercal system by air currents generated due to the wing movements underlying sound production. Singing males still respond to external wind stimulation, but are not startled by the self-generated airflow. To investigate how the nervous system discriminates sensory responses to self-generated and external airflow, we intracellularly recorded wind-sensitive afferents and ventral GIs of the cercal escape pathway in fictively singing crickets, a situation lacking any self-stimulation. GI spiking was reduced whenever cercal wind stimulation coincided with singing motor activity. The axonal terminals of cercal afferents showed no indication of presynaptic inhibition during singing. In two ventral GIs, however, a corollary discharge inhibition occurred strictly in phase with the singing motor pattern. Paired intracellular recordings revealed that this inhibition was not mediated by the activity of the previously identified corollary discharge interneuron (CDI) that rhythmically inhibits the auditory pathway during singing. Cercal wind stimulation, however, reduced the spike activity of this CDI by postsynaptic inhibition. Our study reveals how precisely timed corollary discharge inhibition of ventral GIs can prevent self-generated airflow from triggering inadvertent escape responses in singing crickets. The results indicate that the responsiveness of the auditory and wind-sensitive pathway is modulated by distinct CDIs in singing crickets and that the corollary discharge inhibition in the auditory pathway can be attenuated by cercal wind stimulation. PMID:25318763

Porous silver nanosheets: a novel sensing material for nanoscale and microscale airflow sensors

NASA Astrophysics Data System (ADS)

Marzbanrad, Ehsan; Zhao, Boxin; Zhou, Norman Y.

2015-11-01

Fabrication of nanoscale and microscale machines and devices is one of the goals of nanotechnology. For this purpose, different materials, methods, and devices should be developed. Among them, various types of miniaturized sensors are required to build the nanoscale and microscale systems. In this research, we introduce a new nanoscale sensing material, silver nanosheets, for applications such as nanoscale and microscale gas flow sensors. The silver nanosheets were synthesized through the reduction of silver ions by ascorbic acid in the presence of poly(methacrylic acid) as a capping agent, followed by the growth of silver in the shape of hexagonal and triangular nanoplates, and self-assembly and nanojoining of these structural blocks. At the end of this process, the synthesized nanosheets were floated on the solution. Then, their electrical and thermal stability was demonstrated at 120 °C, and their atmospheric corrosion resistance was clarified at the same temperature range by thermogravimetric analysis. We employed the silver nanosheets in fabricating airflow sensors by scooping out the nanosheets by means of a sensor substrate, drying them at room temperature, and then annealing them at 300 °C for one hour. The fabricated sensors were tested for their ability to measure airflow in the range of 1 to 5 ml min-1, which resulted in a linear response to the airflow with a response and recovery time around 2 s. Moreover, continuous dynamic testing demonstrated that the response of the sensors was stable and hence the sensors can be used for a long time without detectable drift in their response.

Non-atopic males with adult onset asthma are at risk of persistent airflow limitation.

PubMed

Amelink, M; de Nijs, S B; Berger, M; Weersink, E J; ten Brinke, A; Sterk, P J; Bel, E H

2012-05-01

Patients with asthma have on average a more rapid decline in FEV (1) as compared with the general population. Recent cluster analysis has revealed different asthma phenotypes that can be distinguished by age of onset and reversibility of airflow limitation. This study aimed at detecting risk factors associated with persistent airflow limitation in patients with the adult onset asthma phenotype. We recruited 88 patients with adult onset (≥ 18 years) asthma from an academic pulmonary outpatient clinic in the Netherlands. The associations of age, age of asthma onset, asthma duration, gender, race, atopy, smoking pack-years, BMI, use of oral corticosteroids with post-bronchodilator FEV (1) /FVC were investigated. Multiple linear regression analysis showed an association of absence of atopy (r = -0.27, B = -0.26, P = 0.01) and male gender (r = 0.31, B = 0.30, P = 0.004) with post-bronchodilator FEV (1) /FVC. Multiple logistic regression analysis showed that male patients were 10.8 (CI: 2.6-45.2) times the odds than women to have an FEV (1) /FVC < 0.7, and non-atopic patients were 5.2 (CI: 1.3-20.3) times the odds to have an FEV (1) /FVC < 0.7 than atopic patients. We conclude that in patients with adult onset asthma, male gender and absence of atopy are associated with persistent airflow limitation. This might suggest that amongst patients with adult onset asthma, non-atopic male patients are at increased risk of accelerated decline in lung function. © 2012 Blackwell Publishing Ltd.

Transient flow combustion

NASA Technical Reports Server (NTRS)

Tacina, R. R.

1984-01-01

Non-steady combustion problems can result from engine sources such as accelerations, decelerations, nozzle adjustments, augmentor ignition, and air perturbations into and out of the compressor. Also non-steady combustion can be generated internally from combustion instability or self-induced oscillations. A premixed-prevaporized combustor would be particularly sensitive to flow transients because of its susceptability to flashback-autoignition and blowout. An experimental program, the Transient Flow Combustion Study is in progress to study the effects of air and fuel flow transients on a premixed-prevaporized combustor. Preliminary tests performed at an inlet air temperature of 600 K, a reference velocity of 30 m/s, and a pressure of 700 kPa. The airflow was reduced to 1/3 of its original value in a 40 ms ramp before flashback occurred. Ramping the airflow up has shown that blowout is more sensitive than flashback to flow transients. Blowout occurred with a 25 percent increase in airflow (at a constant fuel-air ratio) in a 20 ms ramp. Combustion resonance was found at some conditions and may be important in determining the effects of flow transients.

Airflow reduction during cold weather operation of residential heat recovery ventilators

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGugan, C.A.; Edwards, P.F.; Riley, M.A.

1987-06-01

Laboratory measurements of the performance of residential heat recovery ventilators have been carried out for the R-2000 Energy Efficient Home Program. This work was based on a preliminary test procedure developed by the Canadian Standards Association, part of which calls for testing the HRV under cold weather conditions. An environmental chamber was used to simulate outdoor conditions. Initial tests were carried out with an outdoor temperature of -20/sup 0/C; subsequent tests were carried out at a temperature of -25/sup 0/C. During the tests, airflows, temperatures, and relative humidities of airstreams entering and leaving the HRV, along with electric power inputs,more » were monitored. Frost buildup in the heat exchangers and defrost mechanisms, such as fan shutoff or recirculation, led to reductions in airflows. The magnitude of the reductions is dependent on the design of the heat exchanger and the defrost mechanism used. This paper presents the results of tests performed on a number of HRVs commercially available in Canada at the time of the testing. The flow reductions for the various defrost mechanisms are discussed.« less

Experimental investigation and CFD simulation of multi-pipe earth-to-air heat exchangers (EAHEs) flow performance

NASA Astrophysics Data System (ADS)

Amanowicz, Łukasz; Wojtkowiak, Janusz

2017-11-01

In this paper the experimentally obtained flow characteristics of multi-pipe earth-to-air heat exchangers (EAHEs) were used to validate the EAHE flow performance numerical model prepared by means of CFD software Ansys Fluent. The cut-cell meshing and the k-ɛ realizable turbulence model with default coefficients values and enhanced wall treatment was used. The total pressure losses and airflow in each pipe of multi-pipe exchangers was investigated both experimentally and numerically. The results show that airflow in each pipe of multi-pipe EAHE structures is not equal. The validated numerical model can be used for a proper designing of multi-pipe EAHEs from the flow characteristics point of view. The influence of EAHEs geometrical parameters on the total pressure losses and airflow division between the exchanger pipes can be also analysed. Usage of CFD for designing the EAHEs can be helpful for HVAC engineers (Heating Ventilation and Air Conditioning) for optimizing the geometrical structure of multi-pipe EAHEs in order to save the energy and decrease operational costs of low-energy buildings.

Mechanical Design of a Performance Test Rig for the Turbine Air-Flow Task (TAFT)

NASA Technical Reports Server (NTRS)

Xenofos, George; Forbes, John; Farrow, John; Williams, Robert; Tyler, Tom; Sargent, Scott; Moharos, Jozsef

2003-01-01

To support development of the Boeing-Rocketdyne RS84 rocket engine, a fill-flow, reaction turbine geometry was integrated into the NASA-MSFC turbine air-flow test facility. A mechanical design was generated which minimized the amount of new hardware while incorporating all test and instrUmentation requirements. This paper provides details of the mechanical design for this Turbine Air-Flow Task (TAFT) test rig. The mechanical design process utilized for this task included the following basic stages: Conceptual Design. Preliminary Design. Detailed Design. Baseline of Design (including Configuration Control and Drawing Revision). Fabrication. Assembly. During the design process, many lessons were learned that should benefit future test rig design projects. Of primary importance are well-defined requirements early in the design process, a thorough detailed design package, and effective communication with both the customer and the fabrication contractors. The test rig provided steady and unsteady pressure data necessary to validate the computational fluid dynamics (CFD) code. The rig also helped characterize the turbine blade loading conditions. Test and CFD analysis results are to be presented in another JANNAF paper.

The Nature of Nasal Fricatives: Articulatory-Perceptual Characteristics and Etiologic Considerations.

PubMed

Zajac, David J

2015-07-01

Nasal fricatives (NFs) are unusual, maladaptive articulations used by children both with and without palatal anomalies to replace oral fricatives. Nasal fricatives vary in articulatory, aerodynamic, and acoustic-perceptual characteristics with two generally distinct types recognized. One type is produced with velopharyngeal (VP) constriction that results in turbulent nasal airflow and, frequently, tissue vibration (flutter) at the VP port. Trost (1981) described these as posterior NFs that have a distinctive snorting quality. A second type of NF is produced without significant VP constriction resulting in turbulent airflow generated at the anterior liminal valve of the nose. Of importance, both types are "active" alternative articulations in that the speaker occludes the oral cavity to direct all airflow through the nose (Harding & Grunwell, 1998). It is this oral gesture that differentiates NFs from obligatory (or passive) nasal air escape that may sound similar due to incomplete VP closure. The purpose of this article is to (1) describe the articulatory, aerodynamic, and acoustic-perceptual nature of NFs, and (2) propose a theoretical framework for the acquisition of NFs by children both with and without cleft palate.

Collective odor source estimation and search in time-variant airflow environments using mobile robots.

PubMed

Meng, Qing-Hao; Yang, Wei-Xing; Wang, Yang; Zeng, Ming

2011-01-01

This paper addresses the collective odor source localization (OSL) problem in a time-varying airflow environment using mobile robots. A novel OSL methodology which combines odor-source probability estimation and multiple robots' search is proposed. The estimation phase consists of two steps: firstly, the separate probability-distribution map of odor source is estimated via Bayesian rules and fuzzy inference based on a single robot's detection events; secondly, the separate maps estimated by different robots at different times are fused into a combined map by way of distance based superposition. The multi-robot search behaviors are coordinated via a particle swarm optimization algorithm, where the estimated odor-source probability distribution is used to express the fitness functions. In the process of OSL, the estimation phase provides the prior knowledge for the searching while the searching verifies the estimation results, and both phases are implemented iteratively. The results of simulations for large-scale advection-diffusion plume environments and experiments using real robots in an indoor airflow environment validate the feasibility and robustness of the proposed OSL method.

Collective Odor Source Estimation and Search in Time-Variant Airflow Environments Using Mobile Robots

PubMed Central

Meng, Qing-Hao; Yang, Wei-Xing; Wang, Yang; Zeng, Ming

2011-01-01

This paper addresses the collective odor source localization (OSL) problem in a time-varying airflow environment using mobile robots. A novel OSL methodology which combines odor-source probability estimation and multiple robots’ search is proposed. The estimation phase consists of two steps: firstly, the separate probability-distribution map of odor source is estimated via Bayesian rules and fuzzy inference based on a single robot’s detection events; secondly, the separate maps estimated by different robots at different times are fused into a combined map by way of distance based superposition. The multi-robot search behaviors are coordinated via a particle swarm optimization algorithm, where the estimated odor-source probability distribution is used to express the fitness functions. In the process of OSL, the estimation phase provides the prior knowledge for the searching while the searching verifies the estimation results, and both phases are implemented iteratively. The results of simulations for large-scale advection–diffusion plume environments and experiments using real robots in an indoor airflow environment validate the feasibility and robustness of the proposed OSL method. PMID:22346650

The Nature of Nasal Fricatives: Articulatory-Perceptual Characteristics and Etiologic Considerations

PubMed Central

Zajac, David J.

2015-01-01

Nasal fricatives (NFs) are unusual, maladaptive articulations used by children both with and without palatal anomalies to replace oral fricatives. Nasal fricatives vary in articulatory, aerodynamic, and acoustic-perceptual characteristics with two generally distinct types recognized. One type is produced with velopharyngeal (VP) constriction that results in turbulent nasal airflow and, frequently, tissue vibration (flutter) at the VP port. Trost (1981) described these as posterior NFs that have a distinctive snorting quality. A second type of NF is produced without significant VP constriction resulting in turbulent airflow generated at the anterior liminal valve of the nose. Of importance, both types are “active” alternative articulations in that the speaker occludes the oral cavity to direct all airflow through the nose (Harding & Grunwell, 1998). It is this oral gesture that differentiates NFs from obligatory (or passive) nasal air escape that may sound similar due to incomplete VP closure. The purpose of this article is to (1) describe the articulatory, aerodynamic, and acoustic-perceptual nature of NFs, and (2) propose a theoretical framework for the acquisition of NFs by children both with and without cleft palate. PMID:27057267

An Auto-Tuning PI Control System for an Open-Circuit Low-Speed Wind Tunnel Designed for Greenhouse Technology.

PubMed

Espinoza, Karlos; Valera, Diego L; Torres, José A; López, Alejandro; Molina-Aiz, Francisco D

2015-08-12

Wind tunnels are a key experimental tool for the analysis of airflow parameters in many fields of application. Despite their great potential impact on agricultural research, few contributions have dealt with the development of automatic control systems for wind tunnels in the field of greenhouse technology. The objective of this paper is to present an automatic control system that provides precision and speed of measurement, as well as efficient data processing in low-speed wind tunnel experiments for greenhouse engineering applications. The system is based on an algorithm that identifies the system model and calculates the optimum PI controller. The validation of the system was performed on a cellulose evaporative cooling pad and on insect-proof screens to assess its response to perturbations. The control system provided an accuracy of <0.06 m·s(-1) for airflow speed and <0.50 Pa for pressure drop, thus permitting the reproducibility and standardization of the tests. The proposed control system also incorporates a fully-integrated software unit that manages the tests in terms of airflow speed and pressure drop set points.

Preparation of CNTs rope by electrostatic and airflow field carding with high speed rotor spinning

NASA Astrophysics Data System (ADS)

Dai, J. F.; Liu, J. F.; Zou, J. T.; Dai, Y. L.

2015-12-01

The large-scale preparation of disorderly CNTs with a length larger than 3 mm using CVD method were aligned in polymer monomer airflow fields in a quartz tube with an internal diameter of 200 μm and a length of 1.5 m. The airflow aligned CNTs at the output end of the pipe connects to a copper nozzle with an electrostatic field of applied voltage 5x105 V/m and space length of 0.03 m, which were further realigned using via electrostatic spinning. End to end spray into the high speed rotor twisted single-stranded carbon nanotubes threads via rotor spinning technology. The essential component of this technique was the use of carbon nanotubes at a high rotory speed (200000 r/min) combined with the double twisting of filaments that were twisted together to increase the radial friction of the entire section. SEM micrography showed that carbon nanotube thread has a uniform diameter of approximately 200 μm. Its tensile strength was tested up to 2.7 Gpa, with a length of several meters.

Effect of Phase Lag on Fluid Flow and Particle Dispersion in a Single Human Alveolus

NASA Astrophysics Data System (ADS)

Chhabra, Sudhaker; Prasad, Ajay

2007-11-01

The human lung can be divided into (1) the conducting airways, and (2) the acini. The acini are responsible for gas exchange and consist of alveoli and bronchioles. The acini are useful delivery sites for inhaled therapeutic aerosols. In normal lung function the alveolus expands and contracts in phase with the bronchiole airflow oscillation. Lung diseases such as emphysema compromise the elasticity of the lung. Consequently, the alveolus may not oscillate in-phase with the oscillating bronchiole airflow. We have previously studied flow and particle transport in an alveolus for in-phase flow. The current work focuses on measuring out-of-phase airflow patterns and particle transport in an in-vitro model of a single expanding/contracting human alveolus. The model consists of a transparent, elastic, oscillating alveolus (represented by a 5/6th hemisphere) attached to a rigid circular tube. Realistic tidal breathing conditions were achieved by matching Reynolds and Womersley numbers. Flow patterns were measured using PIV; these velocity maps were subsequently used to calculate particle transport and deposition on the alveolar wall.

Control Valve Trajectories for SOFC Hybrid System Startup

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gorrell, Megan; Banta, Larry; Rosen, William

2012-07-01

Control and management of cathode airflow in a solid oxide fuel cell gas turbine hybrid power system was analyzed using the Hybrid Performance (HyPer) hardware simulation at the National Energy Technology (NETL), U.S. Department of Energy. This work delves into previously unexplored operating practices for HyPer, via simultaneous manipulation of bypass valves and the electric load on the generator. The work is preparatory to the development of a Multi-Input, Multi-Output (MIMO) controller for HyPer. A factorial design of experiments was conducted to acquire data for 81 different combinations of the manipulated variables, which consisted of three air flow control valvesmore » and the electric load on the turbine generator. From this data the response surface for the cathode airflow with respect to bypass valve positions was analyzed. Of particular interest is the control of airflow through the cathode during system startup and during large load swings. This paper presents an algorithm for controlling air mass flow through the cathode based on a modification of the steepest ascent method.« less

A Comprehensive Breath Plume Model for Disease Transmission via Expiratory Aerosols

NASA Astrophysics Data System (ADS)

Halloran, S. K.; Wexler, A. S.; Ristenpart, W. D.

2012-11-01

The peak in influenza incidence during wintertime represents a longstanding unresolved scientific question. One hypothesis is that the efficacy of airborne transmission via aerosols is increased at low humidity and temperature, conditions that prevail in wintertime. Recent experiments with guinea pigs suggest that transmission is indeed maximized at low humidity and temperature, a finding which has been widely interpreted in terms of airborne influenza virus survivability. This interpretation, however, neglects the effect of the airflow on the transmission probability. Here we provide a comprehensive model for assessing the probability of disease transmission via expiratory aerosols between test animals in laboratory conditions. The spread of aerosols emitted from an infected animal is modeled using dispersion theory for a homogeneous turbulent airflow. The concentration and size distribution of the evaporating droplets in the resulting ``Gaussian breath plume'' are calculated as functions of downstream position. We demonstrate that the breath plume model is broadly consistent with the guinea pig experiments, without invoking airborne virus survivability. Moreover, the results highlight the need for careful characterization of the airflow in airborne transmission experiments.

Tuberculosis associated chronic obstructive pulmonary disease.

PubMed

Sarkar, Malay; Srinivasa; Madabhavi, Irappa; Kumar, Kushal

2017-05-01

Reviewed the epidemiology, clinical characteristics, mechanisms, and treatment of tuberculosis associated chronic obstructive pulmonary disease. We searched PubMed, EMBASE, and the CINAHL from inception to June 2016. We used the following search terms: Tuberculosis, COPD, Tuberculosis associated COPD, and so forth. All types of study were chosen. Chronic obstructive pulmonary disease (COPD) and tuberculosis are significant public health problems, particularly in developing countries. Although, smoking is the conventional risk factor for COPD, nonsmoking related risk factors such as biomass fuel exposure, childhood lower-respiratory tract infections, chronic asthma, outdoor air pollution, and prior history of pulmonary tuberculosis have become important risk factors of COPD, particularly in developing countries. Past history of tuberculosis as a risk factor of chronic airflow obstruction has been reported in several studies. It may develop during the course of tuberculosis or after completion of tuberculosis treatment. Developing countries with large burden of tuberculosis can contribute significantly to the burden of chronic airflow obstruction. Prompt diagnosis and treatment of tuberculosis should be emphasized to lessen the future burden of chronic airflow obstruction. © 2017 John Wiley & Sons Ltd.

Air-Abrasive Disinfection of Implant Surfaces in a Simulated Model of Periimplantitis.

PubMed

Quintero, David George; Taylor, Robert Bonnie; Miller, Matthew Braden; Merchant, Keith Roshanali; Pasieta, Scott Anthony

2017-06-01

This in vitro study aimed to evaluate the ability of air-powder abrasion to decontaminate dental implants. Twenty-six implants were inoculated with a Streptococcus sanguinis biofilm media in a novel periimplantitis defect model. Six implants served as controls, and 20 implants were disinfected with either the Cavitron JET Plus or the AIR-FLOW PERIO air-powder abrasion units. Residual bacteria were cultured, and colony forming units (CFUs) were totaled at 24 hours. As expected, negative control implant cultures showed no evidence of viable bacteria. Bacterial growth was observed on all positive control cultures, whereas only 15% of the experimental cultures displayed evidence of viable bacteria. The average CFU per streak for the positive control was 104 compared with a maximum of 10 and 4 CFUs for the Cavitron JET Plus and AIR-FLOW PERIO, respectively. There was a 99.9% reduction in bacteria for both air-powder abrasion instruments. Air-powder abrasion is an effective technique for the decontamination of dental implants, and the Cavitron JET Plus and AIR-FLOW PERIO are equally successful at eliminating viable bacteria from implant surfaces.

Airflow reversal and alternating corkscrew vortices in foredune wake zones during perpendicular and oblique offshore winds

NASA Astrophysics Data System (ADS)

Jackson, Derek W. T.; Beyers, Meiring; Delgado-Fernandez, Irene; Baas, Andreas C. W.; Cooper, Andrew J.; Lynch, Kevin

2013-04-01

On all sandy coastlines fringed by dunes, understanding localised air flow allows us to examine the potential sand transfer between the beach and dunes by wind-blown (Aeolian) action. Traditional thinking into this phenomenon had previously included only onshore winds as effective drivers of this transfer. Recent research by the authors, however, has shown that offshore air-flow too can contribute significantly, through lee-side back eddies, to the overall windblown sediment budget to coastal dunes. Under rising sea levels and increased erosion scenarios, this is an important process in any post-storm recovery of sandy beaches. Until now though, full visualisation in 3D of this newly recognised mechanism in offshore flows has not been achieved. Here, we show for the first time, this return flow eddy system using 3D computational fluid dynamics modelling, and reveal the presence of complex corkscrew vortices and other phenomena. The work highlights the importance of relatively small surface undulations in the dune crest which act to induce the spatial patterns of airflow (and transport) found on the adjacent beach.

The Breath of Planet Earth: Atmospheric Circulation. Assimilation of Surface Wind Observations

NASA Technical Reports Server (NTRS)

Atlas, Robert; Bloom, Stephen; Otterman, Joseph

2000-01-01

Differences in air pressure are a major cause of atmospheric circulation. Because heat excites the movement of atoms, warm temperatures cause, air molecules to expand. Because those molecules now occupy a larger space, the pressure that their weight exerts is decreased. Air from surrounding high-pressure areas is pushed toward the low-pressure areas, creating circulation. This process causes a major pattern of global atmosphere movement known as meridional circulation. In this form of convection, or vertical air movement, heated equatorial air rises and travels through the upper atmosphere toward higher latitudes. Air just above the equator heads toward the North Pole, and air just below the equator moves southward. This air movement fills the gap created where increased air pressure pushes down cold air. The ,cold air moves along the surface back toward the equator, replacing the air masses that rise there. Another influence on atmospheric. circulation is the Coriolis force. Because of the Earth's rotation, large-scale wind currents move in the direction of this axial spin around low-pressure areas. Wind rotates counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. just as the Earth's rotation affects airflow, so too does its surface. In the phenomenon of orographic lifting, elevated topographic features such as mountain ranges lift air as it moves up their surface.

Altitude Wind Tunnel Drive Motor Installation

NASA Image and Video Library

1943-07-21

Construction workers install the drive motor for the Altitude Wind Tunnel (AWT) in the Exhauster Building at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory. The AWT was capable of operating full-scale engines in air density, speed, and temperature similar to that found at high altitudes. The tunnel could produce wind speeds up to 500 miles per hour through a 20-foot-diameter test section at the standard operating altitude of 30,000 feet. The airflow was created by a large wooden fan near the tunnel’s southeast corner. This photograph shows the installation of the 18,000-horsepower drive motor inside the adjoining Exhauster Building in July 1943. The General Electric motor, whose support frame is seen in this photograph, connected to a drive shaft that extended from the building, through the tunnel shell, and into a 12-bladed, 31-foot-diameter spruce wood fan. Flexible couplings on the shaft allowed for the movement of the shell. The corner of the Exhauster Building was built around the motor after its installation. The General Electric induction motor could produce 10 to 410 revolutions per minute and create wind speeds up to 500 miles per hour, or Mach 0.63, at 30,000 feet. The AWT became operational in January 1944 and tested piston, turbojet and ramjet engines for nearly 20 years.

Summary and Analysis of Horizontal-Tail Contribution to Longitudinal Stability of Swept-Wing Airplanes at Low Speeds

NASA Technical Reports Server (NTRS)

Neely, Robert H.; Griner, Roland F.

1959-01-01

Air-flow characteristics behind wings and wing-body combinations are described and are related to the downwash at specific tall locations for unseparated and separated flow conditions. The effects of various parameters and control devices on the air-flow characteristics and tail contribution are analyzed and demonstrated. An attempt has been made to summarize certain data by empirical correlation or theoretical means in a form useful for design. The experimental data herein were obtained mostly at Reynolds numbers greater than 4 x 10(exp 6) and at Mach numbers less than 0.25.

Simplified Space Conditioning in Low-Load Homes: Results from Pittsburgh, Pennsylvania, New Construction Unoccupied Test House

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poerschke, Andrew; Stecher, Dave

2014-06-01

Field testing was performed in a new construction unoccupied test house in Pittsburgh, PA. Four air-based heating, ventilation, and air conditioning distribution systems—a typical airflow ducted system to the bedrooms, a low airflow ducted system to the bedrooms, a system with transfer fans to the bedrooms, and a system with no ductwork to the bedrooms—were evaluated during heating, cooling, and midseason conditions. The relative ability of each system was assessed with respect to relevant Air Conditioning Contractors of America and ASHRAE standards for house temperature uniformity and stability, respectively.

Simplified Space Conditioning in Low-Load Homes: Results from Pittsburgh, Pennsylvania, New Construction Unoccupied Test House

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poerschke, A.; Stecher, D.

2014-06-01

Field testing was performed in a new construction unoccupied test house in Pittsburgh, Pennsylvania. Four air-based heating, ventilation, and air conditioning distribution systems--a typical airflow ducted system to the bedrooms, a low airflow ducted system to the bedrooms, a system with transfer fans to the bedrooms, and a system with no ductwork to the bedrooms--were evaluated during heating, cooling, and midseason conditions. The relative ability of each system was assessed with respect to relevant Air Conditioning Contractors of America and ASHRAE standards for house temperature uniformity and stability, respectively.

Test data report, low speed wind tunnel tests of a full scale lift/cruise-fan inlet, with engine, at high angles of attack

NASA Technical Reports Server (NTRS)

Shain, W. M.

1978-01-01

A low speed wind tunnel test of a fixed lip inlet with engine, was performed. The inlet was close coupled to a Hamilton Standard 1.4 meter, variable pitch fan driven by a lycoming T55-L-11A engine. Tests were conducted with various combinations of inlet angle of attack freestream velocities, and fan airflows. Data were recorded to define the inlet airflow separation boundaries, performance characteristics, and fan blade stresses. The test model, installation, instrumentation, test, data reduction and final data are described.

A numerical study of the effects of a large sandbar upon sea breeze development

NASA Technical Reports Server (NTRS)

Kessler, R. C.; Pielke, R. A.; Mcqueen, J.; Eppel, D.

1985-01-01

Two-dimensional numerical simulations of sea breeze development over a large sandbar on the North Sea coast of Germany are reported. The numerical model used in these experiments contains a detailed treatment of soil moisture, which allows evaluation of the effects of differential surface characteristics on the airflow pattern. Results of the simulations indicate that the contrast between the moist sandbar and adjacent dry land, the tidal inundation of the sandbar, and the westward penetration of the Baltic sea breeze play important roles in the development of mesoscale airflow patterns in the sandbar region.

Single-stage electrohydraulic servosystem for actuating on airflow valve with frequencies to 500 hertz

NASA Technical Reports Server (NTRS)

Webb, J. A., Jr.; Mehmed, O.; Lorenzo, C. F.

1980-01-01

An airflow valve and its electrohydraulic actuation servosystem are described. The servosystem uses a high-power, single-stage servovalve to obtain a dynamic response beyond that of systems designed with conventional two-stage servovalves. The electrohydraulic servosystem is analyzed and the limitations imposed on system performance by such nonlinearities as signal saturations and power limitations are discussed. Descriptions of the mechanical design concepts and developmental considerations are included. Dynamic data, in the form of sweep-frequency test results, are presented and comparison with analytical results obtained with an analog computer model is made.