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Artykuły w czasopismach na temat „Airflow measurements”

Autor: Grafiati

Data publikacji: 4 czerwca 2021

Data aktualizacji: 2 lutego 2022

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1

De Vogeleer, Gerlinde, Peter Demeyer, Philippe Van Overbeke i Jan G. Pieters. "Assessing Airflow Distribution in Vents of a Naturally Ventilated Test Facility Using Reference Air Velocity Measurements". Transactions of the ASABE 61, nr 3 (2018): 1065–76. http://dx.doi.org/10.13031/trans.12458.

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Abstract. Emission measurement in naturally ventilated buildings is a complex task because wind conditions can change quickly, inducing high spatial and temporal variations in the air velocity and pollutant concentration at the vent level. Simply taking the product of differential pollutant concentration and airflow rate may generate inaccurate results because the limited number of measurement locations usually fails to correctly reflect the velocity and concentration distributions in the vents. To assess the predictability of the airflow distribution in the vents of a naturally ventilated building, detailed measurements were conducted in the vents. Linear regression was applied to velocity measurements taken in the vents and at a 10 m mast (meteomast) located 20 m away. The detailed airflow measurements were used to validate statistical models. Results showed that the velocity distribution in the ridge vent could be modeled accurately and precisely for all wind directions (R2 > 89%). Models for unidirectional airflows showed high predictability for the side vent (R2 > 92%). Models for bidirectional airflows showed good predictability for the windward side when the air flowed in the same direction as the outside wind (R2 > 88%) but showed less accurate results for the leeward side as well as for airflows moving in the opposite direction to the outside wind. For all models and wind directions, the most important input variable was the velocity component measured perpendicular to the vents at the meteomast. The importance of the velocity component measured parallel to the vents increased near the edges of the vent when the vent was on the windward side but did not reach the importance of the perpendicular component. The results confirmed the importance of using different models for unidirectional and bidirectional airflows to obtain accurate airflow assessments. Keywords: Airflow rate distribution, Mock-up building, Natural ventilation, Ultrasonic anemometer.

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Marano, Giuseppe. "Airflow measurements in small animals". Laboratory Animals 28, nr 3 (1.07.1994): 239–43. http://dx.doi.org/10.1258/002367794780681624.

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Monitoring respiratory airflow is extremely important in pharmacological studies of the respiratory system. However, in mechanically ventilated small animals (e.g. rats and guinea pigs) the use of a commercial pneumotachometer, attached directly to the tracheal cannula, substantially increases the equipment dead space (the volume shared by inspired and expired gases). Since apparatus dead space must be added to the tidal volume (determined on the basis of ventilatory rate and animal body weight) necessary to meet the respiratory needs of the animal, the resulting stroke volume is greatly increased, specially in very small animals. This results in an increase in intrathoracic pressure which is potentially associated with a decrease in venous return, cardiac output, and arterial pressure. The author investigated the possibility of avoiding the potential problems of the added instrumental dead space by software-summing the separate flows measured on the inflation and deflation limbs of the breathing circuit. This study shows that the summation of the flow signals obtained from separate pneumotachometers on the inspiratory and expiratory arms of the breathing circuit is not dissimilar to the total flow as measured by a pneumotachometer directly attached to the tracheal cannula and that the method here described can be an advantageous alternative to the employment of a single pneumotachometer.

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3

Tang, Xiaoning, i Xiong Yan. "Airflow resistance of acoustical fibrous materials: Measurements, calculations and applications". Journal of Industrial Textiles 49, nr 8 (15.10.2018): 981–1010. http://dx.doi.org/10.1177/1528083718805714.

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The acoustic performance of fibrous materials is mainly determined by its airflow resistance, and it is a parameter of the resistance that the airflow meets through the materials. This paper has summarized the recent advances on the measurements, calculations and applications of airflow resistance. Firstly, different methods for airflow resistance measurements are presented, mainly including the direct airflow method, alternating airflow method and acoustical method. We have summarized the development history, current status and industrial applications of these methods. Secondly, this paper has summarized the models of calculating airflow resistance. Most of these empirical models are based on the characteristic parameters of fibrous materials, for instance bulk density, fiber diameter, porosity and thickness. Thirdly, this review has gathered the applications of airflow resistance in sound absorption and noise control. It is a crucial parameter in the prediction of both normal incidence sound absorption and reverberation chamber sound absorption. In conclusion, this review has concluded with some perspectives for the measurements, calculations and applications of airflow resistance.

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4

M'zoughi, Fares, Izaskun Garrido, Aitor J. Garrido i Manuel De La Sen. "ANN-Based Airflow Control for an Oscillating Water Column Using Surface Elevation Measurements". Sensors 20, nr 5 (29.02.2020): 1352. http://dx.doi.org/10.3390/s20051352.

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Oscillating water column (OWC) plants face power generation limitations due to the stalling phenomenon. This behavior can be avoided by an airflow control strategy that can anticipate the incoming peak waves and reduce its airflow velocity within the turbine duct. In this sense, this work aims to use the power of artificial neural networks (ANN) to recognize the different incoming waves in order to distinguish the strong waves that provoke the stalling behavior and generate a suitable airflow speed reference for the airflow control scheme. The ANN is, therefore, trained using real surface elevation measurements of the waves. The ANN-based airflow control will control an air valve in the capture chamber to adjust the airflow speed as required. A comparative study has been carried out to compare the ANN-based airflow control to the uncontrolled OWC system in different sea conditions. Also, another study has been carried out using real measured wave input data and generated power of the NEREIDA wave power plant. Results show the effectiveness of the proposed ANN airflow control against the uncontrolled case ensuring power generation improvement.

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5

Miller, Creighton J., i Raymond Daniloff. "Airflow measurements: Theory and utility of findings". Journal of Voice 7, nr 1 (marzec 1993): 38–46. http://dx.doi.org/10.1016/s0892-1997(05)80110-9.

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6

Blonshine, Susan, i Michael D. Goldman. "Optimizing Performance of Respiratory Airflow Resistance Measurements". Chest 134, nr 6 (grudzień 2008): 1304–9. http://dx.doi.org/10.1378/chest.06-2898.

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7

Wodziak, Waldemar, i Jacek Sobczyk. "PIV measurements of airflow past multiple cylinders". EPJ Web of Conferences 180 (2018): 02121. http://dx.doi.org/10.1051/epjconf/201817002121.

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Wodziak, Waldemar, i Jacek Sobczyk. "PIV measurements of airflow past multiple cylinders". EPJ Web of Conferences 180 (2018): 02121. http://dx.doi.org/10.1051/epjconf/201818002121.

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Flow characteristics in vicinity of six circular cylinders aligned inline was investigated experimentally by means of PIV method. Experiments were conducted in a low speed closed circuit wind tunnel. Inflow velocity was 1.2 m/s which corresponds to Re=1600 based on the cylinder diameter. Spacing ratio between cylinders L/D was 1.5. Instantaneous and averaged velocity fields were presented. Experiments were designed in order to use their results as a test case for future numerical calculations.

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9

Pesic, Radivoje, Aleksandar Davinic, Snezana Petkovic, Dragan Taranovic i Danijela Miloradovic. "Aspects of volumetric efficiency measurement for reciprocating engines". Thermal Science 17, nr 1 (2013): 35–48. http://dx.doi.org/10.2298/tsci120531153p.

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The volumetric efficiency significantly influences engine output. Both design and dimensions of an intake and exhaust system have large impact on volumetric efficiency. Experimental equipment for measuring of airflow through the engine, which is placed in the intake system, may affect the results of measurements and distort the real picture of the impact of individual structural factors. This paper deals with the problems of experimental determination of intake airflow using orifice plates and the influence of orifice plate diameter on the results of the measurements. The problems of airflow measurements through a multi-process Otto/Diesel engine were analyzed. An original method for determining volumetric efficiency was developed based on in-cylinder pressure measurement during motored operation, and appropriate calibration of the experimental procedure was performed. Good correlation between the results of application of the original method for determination of volumetric efficiency and the results of theoretical model used in research of influence of the intake pipe length on volumetric efficiency was determined.

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10

Ferdyn-Grygierek, Joanna, Andrzej Baranowski, Monika Blaszczok i Jan Kaczmarczyk. "Thermal Diagnostics of Natural Ventilation in Buildings: An Integrated Approach". Energies 12, nr 23 (29.11.2019): 4556. http://dx.doi.org/10.3390/en12234556.

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Diagnostics of natural ventilation in buildings is problematic, as the airflow rate changes considerably over time. One constant average airflow is usually assumed when calculating energy demand for a building, however, such a simplification could be fraught with considerable error. The paper describes a comprehensive methodology for the diagnostics of a natural ventilation system in a building and its practical application. Based on in situ measurements and simulations in two existing buildings (dwelling house and school) in Poland, the real values of the ventilating airflows were analyzed and resulting heat demand was compared with the design values. The pros and cons of various methods for evaluation of natural ventilation are discussed. The real airflow was determined by measurements in a ventilation grille or by a tracer gas concentration decay method. The airtightness of the buildings’ envelope was evaluated based on the fan pressurization test. The last stage entailed computer simulations of air exchange in buildings using CONTAM software. The multizone models of the buildings were calibrated and verified with existing measured data. Measured airflow in a multifamily house was small and substantially deviated from the Polish standard. In case of a school, the air flow rate amounted to an average of 10% of the required value. Calculation of the heat demand for ventilation based on the standard value of the airflow led to a considerable overestimation of this value in relation to the real consumption. In the analyzed cases, the difference was 40% for the school and 30% for the residential building.

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11

Eccles, R. "A guide to practical aspects of measurement of human nasal airflow by rhinomanometry". Rhinology journal 49, nr 1 (1.03.2011): 2–10. http://dx.doi.org/10.4193/rhino10.065.

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The guide is intended for all those interested in measuring human nasal airflow by rhinomanometry, either for clinical or research purposes. The guide is written in non-technical language so that it may be understood by nursing and support staff who may need to make measurements using rhinomanometry. It is not a systematic review of the literature but a personal view based on over 40 years experience of measuring nasal airflow. The guide introduces the basic principles of nasal airflow and pressure and their measurement. The following topics are discussed: anterior and posterior rhinomanometry and their relative problems and benefits, control of errors in measurement, standard operating procedures, calibration of equipment, measurement of the totally obstructed nose, reproducibility and sensitivity of rhinomanometry, hygiene, factors influencing nasal airflow such as rest and exercise, alcohol, medicines, temperature and humidity and diseases such as common cold and allergy.

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12

Ebner, P. P., S. A. Grimm, M. Schneebeli i A. Steinfeld. "An instrumented sample holder for time-lapse microtomography measurements of snow under advective airflow". Geoscientific Instrumentation, Methods and Data Systems 3, nr 2 (24.09.2014): 179–85. http://dx.doi.org/10.5194/gi-3-179-2014.

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Abstract. An instrumented sample holder was developed for time-lapse microtomography of snow samples to enable in situ nondestructive spatial and temporal measurements under controlled advective airflows, temperature gradients, and air humidities. The design was aided by computational fluid dynamics simulations to evaluate the airflow uniformity across the snow sample. Morphological and mass transport properties were evaluated during a 4-day test run. This instrument allows the experimental characterization of metamorphism of snow undergoing structural changes with time.

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13

Ebner, P. P., S. A. Grimm, M. Schneebeli i A. Steinfeld. "An instrumented sample holder for time-lapse micro-tomography measurements of snow under advective airflow". Geoscientific Instrumentation, Methods and Data Systems Discussions 4, nr 1 (24.06.2014): 353–73. http://dx.doi.org/10.5194/gid-4-353-2014.

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Abstract. An instrumented sample holder was developed for time-lapse micro-tomography of snow samples to enable in-situ nondestructive spatial and temporal measurements under controlled advective airflows, temperature gradients, and air humidities. The design was aided by computational fluid dynamics simulations to evaluate the airflow uniformity across the snow sample. Morphological and mass transport properties were evaluated during a 4 day test run. This instrument allows the experimental characterization of metamorphism of snow undergoing structural changes with time.

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14

Lopresti, Erika R., Arthur T. Johnson, Frank C. Koh, William H. Scott, Shaya Jamshidi i Nischom K. Silverman. "Testing limits to airflow perturbation device (APD) measurements". BioMedical Engineering OnLine 7, nr 1 (2008): 28. http://dx.doi.org/10.1186/1475-925x-7-28.

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Danišovič, Peter, Juraj Šrámek, Michal Hodoň i Martin Húdik. "Testing measurements of airflow velocity in road tunnels". MATEC Web of Conferences 117 (2017): 00035. http://dx.doi.org/10.1051/matecconf/201711700035.

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16

Weir, M. J. C. "AIRFLOW PATTERNS FROM PHOTOGRAMMETRIC MEASUREMENTS OF WINDBLOWN TIMBER". Photogrammetric Record 7, nr 42 (26.08.2006): 731–36. http://dx.doi.org/10.1111/j.1477-9730.1973.tb01213.x.

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Whicker, Jeffrey J., Guy D. Baker i Piotr T. Wasiolek. "QUANTITATIVE MEASUREMENTS OF AIRFLOW INSIDE A NUCLEAR LABORATORY". Health Physics 79, nr 6 (grudzień 2000): 712–21. http://dx.doi.org/10.1097/00004032-200012000-00018.

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18

Panov, A. P., i A. N. Serov. "Measurements of the Airflow Velocity Using Ultrasonic Transducers". Russian Microelectronics 48, nr 7 (grudzień 2019): 501–5. http://dx.doi.org/10.1134/s1063739719070096.

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19

Bard, Michael C., Thomas V. McCaffrey, David H. Slavit i Richard J. Lipton. "Noninvasive Technique for Estimating Subglottic Pressure and Laryngeal Efficiency". Annals of Otology, Rhinology & Laryngology 101, nr 7 (lipiec 1992): 578–82. http://dx.doi.org/10.1177/000348949210100706.

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The clinical assessment of aerodynamic parameters is important in the physiology and pathophysiology of laryngeal function. Vocal efficiency is among these objective measurements and can be calculated from simultaneous recordings of subglottic pressure, airflow, and sound intensity. Modern techniques allow us to accurately determine sound intensity and airflow. However, methods to determine subglottic pressure are either invasive or laborious. We have evaluated a noninvasive, indirect method to determine subglottic pressure by using a technique based on the interruption of transglottic airflow during phonation. The correlation between the indirectly acquired subglottic pressure measured in the oral cavity by using this technique and the subglottic pressure obtained directly by translaryngeal puncture in human volunteers was highly significant in 35 trials (r = .92, p < .01). This study describes a reliable technique for the noninvasive measurement of subglottic pressure, sound intensity, and airflow.

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20

Bolberg, Mads. "How small-scale variation in mineral wool products effect random incidence sound absorption". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, nr 4 (1.08.2021): 2313–17. http://dx.doi.org/10.3397/in-2021-2103.

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Mineral wool products are produced by creating a spray of fibres, that is collected and made into slabs. This randomized spray can lead to small variations across a slab. Nevertheless, mineral wool slabs are often treated in acoustics as locally reacting perfectly homogeneous, isotropic materials. This means that small-scale characterisations are extrapolated to large-scale without considering the impact from possible variations in a large-scale setup. The question is how the small-scale characterisations should be used for large-scale setups with this in mind. Three products with the same thickness and density, but with significantly different specific airflow resistances were selected for random incidence sound absorption tests. The products were all specially made ceiling tiles and measurements were conducted in E200 setup according to ISO 354:2003. The tiles were gradually exchanged in a random fashion, so measurement results were obtained using a combination of tiles with different specific airflow resistances. Results showed a surprisingly linear relation between the sound absorption and the average specific airflow resistance of tiles used in the measurements. The results point to that variations in products must be observed, but also that small variations in specific airflow resistance in standardized products are insignificant.

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21

Garman, K. E., K. A. Hill, P. Wyss, M. Carlsen, J. R. Zimmerman, B. H. Stirm, T. Q. Carney, R. Santini i P. B. Shepson. "An Airborne and Wind Tunnel Evaluation of a Wind Turbulence Measurement System for Aircraft-Based Flux Measurements*". Journal of Atmospheric and Oceanic Technology 23, nr 12 (1.12.2006): 1696–708. http://dx.doi.org/10.1175/jtech1940.1.

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Abstract Although the ability to measure vertical eddy fluxes of gases from aircraft platforms represents an important capability to obtain spatially resolved data, accurate and reliable determination of the turbulent vertical velocity presents a great challenge. A nine-hole hemispherical probe known as the “Best Air Turbulence Probe” (often abbreviated as the “BAT Probe”) is frequently used in aircraft-based flux studies to sense the airflow angles and velocity relative to the aircraft. Instruments such as inertial navigation and global positioning systems allow the measured airflow to be converted into the three-dimensional wind velocity relative to the earth’s surface by taking into account the aircraft’s velocity and orientation. Calibration of the aircraft system has previously been performed primarily through in-flight experiments, where calibration coefficients were determined by performing various flight maneuvers. However, a rigorous test of the BAT Probe in a wind tunnel has not been previously undertaken. The authors summarize the results of a complement of low-speed wind tunnel tests and in-flight calibrations for the aircraft–BAT Probe combination. Two key factors are addressed in this paper: The first is the correction of systematic error arising from airflow measurements with a noncalibrated BAT Probe. The second is the instrumental precision in measuring the vertical component of wind from the integrated aircraft-based wind measurement system. The wind tunnel calibration allows one to ascertain the extent to which the BAT Probe airflow measurements depart from a commonly used theoretical potential flow model and to correct for systematic errors that would be present if only the potential flow model were used. The precision in the determined vertical winds was estimated by propagating the precision of the BAT Probe data (determined from the wind tunnel study) and the inertial measurement precision (determined from in-flight tests). The precision of the vertical wind measurement for spatial scales larger than approximately 2 m is independent of aircraft flight speed over the range of airspeeds studied, and the 1σ precision is approximately 0.03 m s−1.

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22

Hernandez Bennetts, Victor, Kamarulzaman Kamarudin, Thomas Wiedemann, Tomasz Kucner, Sai Somisetty i Achim Lilienthal. "Multi-Domain Airflow Modeling and Ventilation Characterization Using Mobile Robots, Stationary Sensors and Machine Learning". Sensors 19, nr 5 (5.03.2019): 1119. http://dx.doi.org/10.3390/s19051119.

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Ventilation systems are critically important components of many public buildings and workspaces. Proper ventilation is often crucial for preventing accidents, such as explosions in mines and avoiding health issues, for example, through long-term exposure to harmful respirable matter. Validation and maintenance of ventilation systems is thus of key interest for plant operators and authorities. However, methods for ventilation characterization, which allow us to monitor whether the ventilation system in place works as desired, hardly exist. This article addresses the critical challenge of ventilation characterization—measuring and modelling air flow at micro-scales—that is, creating a high-resolution model of wind speed and direction from airflow measurements. Models of the near-surface micro-scale flow fields are not only useful for ventilation characterization, but they also provide critical information for planning energy-efficient paths for aerial robots and many applications in mobile robot olfaction. In this article we propose a heterogeneous measurement system composed of static, continuously sampling sensing nodes, complemented by localized measurements, collected during occasional sensing missions with a mobile robot. We introduce a novel, data-driven, multi-domain airflow modelling algorithm that estimates (1) fields of posterior distributions over wind direction and speed (“ventilation maps”, spatial domain); (2) sets of ventilation calendars that capture the evolution of important airflow characteristics at measurement positions (temporal domain); and (3) a frequency domain analysis that can reveal periodic changes of airflow in the environment. The ventilation map and the ventilation calendars make use of an improved estimation pipeline that incorporates a wind sensor model and a transition model to better filter out sporadic, noisy airflow changes. These sudden changes may originate from turbulence or irregular activity in the surveyed environment and can, therefore, disturb modelling of the relevant airflow patterns. We tested the proposed multi-domain airflow modelling approach with simulated data and with experiments in a semi-controlled environment and present results that verify the accuracy of our approach and its sensitivity to different turbulence levels and other disturbances. Finally, we deployed the proposed system in two different real-world industrial environments (foundry halls) with different ventilation regimes for three weeks during full operation. Since airflow ground truth cannot be obtained, we present a qualitative discussion of the generated airflow models with plant operators, who concluded that the computed models accurately depicted the expected airflow patterns and are useful to understand how pollutants spread in the work environment. This analysis may then provide the basis for decisions about corrective actions to avoid long-term exposure of workers to harmful respirable matter.

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Cowie, Robert L., Margot F. Underwood i Stephen K. Field. "Asthma Symptoms Do not Predict Spirometry". Canadian Respiratory Journal 14, nr 6 (2007): 339–42. http://dx.doi.org/10.1155/2007/816132.

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BACKGROUND: Asthma is a disease characterized by variable airflow obstruction, but the measurement of airflow is often omitted in the process of diagnosis and management of the disease.OBJECTIVES: Features of asthma severity and control were examined to determine the extent to which objective measurements, including forced expiratory volume in 1 s and forced expiratory volume in 1 s/forced vital capacity, correlated with other manifestations of the disease.METHODS: Subjects were a consecutive sample of patients with asthma attending a university-based asthma clinic. All subjects underwent routine assessment using a standard questionnaire and spirometry.RESULTS: A total of 500 subjects were included in the present study, and their assessment showed that neither symptoms nor history could predict or be predicted by their measurements of lung function.CONCLUSION: Routine measurement of lung function should be performed on subjects with asthma if normal or near-normal lung function is a desired component of asthma control.

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Scaar, H., U. Praeger, M. Spuhler, D. A. Neuwald, I. Truppel, M. Linke, K. Gottschalk, M. König, J. N. Wünsche i M. Geyer. "Wind tunnel airflow measurements on plastic apple storage bins". Acta Horticulturae, nr 1194 (marzec 2018): 1321–28. http://dx.doi.org/10.17660/actahortic.2018.1194.186.

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Kisilewicz, T., i K. Nowak-Dzieszko. "Low airflow measurements by means of gas tracing method". IOP Conference Series: Materials Science and Engineering 415 (1.11.2018): 012030. http://dx.doi.org/10.1088/1757-899x/415/1/012030.

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Jiang, Jack, Timothy O'Mara, David Conley i David Hanson. "Phonation threshold pressure measurements during phonation by airflow interruption". Laryngoscope 109, nr 3 (marzec 1999): 425–32. http://dx.doi.org/10.1097/00005537-199903000-00016.

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Fishwick, D., R. Barraclough, T. Pickering, A. Fletcher, R. Lewis, R. Niven i C. J. Warburton. "Comparison of various airflow measurements in symptomatic textile workers". Occupational Medicine 60, nr 8 (15.09.2010): 631–34. http://dx.doi.org/10.1093/occmed/kqq135.

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Pedersen, T. F. "On wind turbine power performance measurements at inclined airflow". Wind Energy 7, nr 3 (lipiec 2004): 163–76. http://dx.doi.org/10.1002/we.112.

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Cui, Can, Wenjian Cai i Haoran Chen. "Airflow measurements using averaging Pitot tube under restricted conditions". Building and Environment 139 (lipiec 2018): 17–26. http://dx.doi.org/10.1016/j.buildenv.2018.05.014.

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Eftekhari, M. M., i D. J. Pinnock. "Natural ventilation: Airflow measurements in a lightweight test room". Building Services Engineering Research and Technology 19, nr 1 (luty 1998): 37–42. http://dx.doi.org/10.1177/014362449801900107.

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Pogosov, G. A., i N. Sh Khaikin. "Doppler measurements of relative airflow velocities using CO2 lasers". Measurement Techniques 36, nr 11 (listopad 1993): 1247–50. http://dx.doi.org/10.1007/bf00978175.

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Vernay, Didier G., Benny Raphael i Ian F. C. Smith. "Augmenting simulations of airflow around buildings using field measurements". Advanced Engineering Informatics 28, nr 4 (październik 2014): 412–24. http://dx.doi.org/10.1016/j.aei.2014.06.003.

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Cheong, K. W. "Tracer gas technology for airflow measurements in HVAC systems". International Journal of Energy Research 20, nr 12 (grudzień 1996): 1081–93. http://dx.doi.org/10.1002/(sici)1099-114x(199612)20:12<1081::aid-er236>3.0.co;2-o.

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Tamura, Kaori, Sayaka Matsumoto, Yu Hsuan Tseng, Takayuki Kobayashi, Jun’ichi Miwa, Ken’ichi Miyazawa, Toyotaka Hirao i in. "Physiological and subjective comfort evaluation under different airflow directions in a cooling environment". PLOS ONE 16, nr 4 (14.04.2021): e0249235. http://dx.doi.org/10.1371/journal.pone.0249235.

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Indoor comfort is influenced by airflow direction, but subjective evaluations can differ. This study evaluates the airflow comfort with subjective assessments and physiological measurements, including skin temperature, electroencephalograms, and electrocardiograms. Nineteen participants entered a test room at 20°C after staying in a room at 32°C for acclimation. They were exposed to indirect and direct airflow conditions to their faces and performed four tasks under each condition: resting, counting to 10 s following time alerts, counting to 10 s in mind, and mental calculation. Subjective assessments showed relatively higher thermal sensation and pleasantness under indirect airflow. The psychological time calculated from counting behaviors was longer under indirect airflow, indicating suppression of negative emotions. The face temperatures significantly declined during experiments under direct airflow. The beta and gamma bands of electroencephalograms were inhibited under the indirect condition, and these amplitudes were negatively correlated with pleasant feelings. Electrocardiogram parameters indicated that sympathetic nervous activity was predominant during counting, following alerts and mental calculation in indirect airflow. This study supports the comfort of indirect airflow based on reliable evidence.

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Rodríguez Vercher, Juan Carlos, Romina del Rey i Jesús Alba. "Indirect determination of airflow resistance of textiles with reference samples". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, nr 3 (1.08.2021): 3708–13. http://dx.doi.org/10.3397/in-2021-2495.

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Airflow resistance is a non-acoustic parameter of great relevance in the acoustic characterization of porous materials. It is used in several sound absorbing material prediction models and it is also a control parameter for acoustic conditioning and insulation in different building solutions. The ISO 9053 standard defines several methods to obtain it, using both direct measurements and indirect techniques. However, both procedures may involve problems related to the placement of the textile samples in the tube or to the stability of the samples during testing. In this work, the use of reference materials to stabilize the measurement of thin materials is proposed. Airflow resistance results obtained for different materials in an impedance tube are presented. The tests have been carried out by following the Ingard & Dear method, as an indirect technique accepted by the standard. Several material compositions with a wide range of airflow resistance values have been analyzed with different reference materials.

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Hoff, Steven J., Dwaine S. Bundy, Minda A. Nelson, Brian C. Zelle, Larry D. Jacobson, Albert J. Heber, Jiqin Ni, Yuanhui Zhang, Jacek A. Koziel i David B. Beasley. "Real-Time Airflow Rate Measurements from Mechanically Ventilated Animal Buildings". Journal of the Air & Waste Management Association 59, nr 6 (czerwiec 2009): 683–94. http://dx.doi.org/10.3155/1047-3289.59.6.683.

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E. Franz, L. F. Bouse i J. C. Brusse. "System for In-flight Airflow Measurements of an Agricultural Aircraft". Transactions of the ASAE 39, nr 6 (1996): 1961–69. http://dx.doi.org/10.13031/2013.27697.

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L. F. Bouse, E. Franz i J. C. Brusse. "In-flight Airflow Measurements of a Cessna AgHusky Agricultural Aircraft". Transactions of the ASAE 39, nr 6 (1996): 1971–76. http://dx.doi.org/10.13031/2013.27698.

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Kook Kim, Jin, Joo-Heon Yoon, Chang Hoon Kim, Tae Wook Nam, Dae Bo Shim i Hyang Ae Shin. "Particle image velocimetry measurements for the study of nasal airflow". Acta Oto-Laryngologica 126, nr 3 (styczeń 2006): 282–87. http://dx.doi.org/10.1080/00016480500361320.

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Allil, Alexandre Silva, Fábio da S. Dutra, Marcelo Martins Werneck, Regina Célia da Silva Barros Allil i Cesar Cosenza De Carvalho. "Optoelectronic sensor applied to airflow velocity measurements on flare systems". Rio Oil and Gas Expo and Conference 20, nr 2020 (1.12.2020): 226–27. http://dx.doi.org/10.48072/2525-7579.rog.2020.226.

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Ceylan, Seyit M., Mahmut A. Kanmaz, Ilyas Disikirik i Pinar G. Karadeniz. "Peak nasal inspiratory airflow measurements for assessing laryngopharyngeal reflux treatment". Clinical Otolaryngology 46, nr 4 (21.02.2021): 796–801. http://dx.doi.org/10.1111/coa.13737.

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NI, J. Q., A. J. HEBER, T. T. LIM, C. A. DIEHL, R. K. DUGGIRALA i B. L. HAYMORE. "Hydrogen sulphide emission from two large pig-finishing buildings with long-term high-frequency measurements". Journal of Agricultural Science 138, nr 2 (marzec 2002): 227–36. http://dx.doi.org/10.1017/s0021859601001824.

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Hydrogen sulphide (H2S) is a common toxic air pollutant and is emitted from decomposing manure at animal facilities. However, there have been only a few studies of H2S emissions from animal buildings, especially those involving long-term, high-frequency measurements. In the current study, H2S emissions from two, 1000-head pig-finishing buildings in Illinois, USA, were monitored with a high-frequency measurement system for 6 months in 1997 during two, partial, pig-growth cycles. Air sample streams were continuously taken from the pit headspace, and the pit and wall fan exhaust air. Hydrogen sulphide concentration was measured at each location with H2S converters and sulphur dioxide (SO2) analysers during 16 or 24 sampling cycles per day, resulting in 4544 sampling cycles and 219 days of reliable data. Building ventilation rate was the summation of pit fan and wall fan airflow rates. Airflow rates of the underfloor manure pit fans were measured directly with full-size impeller anemometers or calculated from airflow/voltage relationships of the fans. Airflow rates of the wall fans were calculated from fan operation and differential static pressure data and fan performance curves. Mean H2S emission was 0·59 kg/day per building, 0·74 g/day per m2 of pit surface area, or 6·3 g/day per animal unit (AU = 500 kg animal weight). The determination of H2S emission per AU was restricted to 193 days when building occupancy was at least 700 pigs per building. Higher temperatures and building ventilation rates resulted in significantly higher H2S emissions per AU.

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Smith, Bonnie E., Thomas W. Guyette, Yash Patil i Timothy S. Brannan. "Pressure-Flow Measurements for Selected Nasal Sound Segments Produced by Normal Children and Adolescents". Cleft Palate-Craniofacial Journal 40, nr 2 (marzec 2003): 158–64. http://dx.doi.org/10.1597/1545-1569_2003_040_0158_pfmfsn_2.0.co_2.

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Objective The purpose of this prospective study was to: (1) report simultaneous oral-nasal pressures, nasal airflow rates, and velopharyngeal orifice areas for nasal sounds produced by children and adolescents; (2) determine whether data could be statistically classified by age, sex, or utterance type; and (3) provide guidelines for determining typical from atypical productions. Participants The study involved 56 subjects, with two boys and two girls representing each age from 5 to 18 years. Subjects had no history of speech therapy, were judged as having normal speech and resonance at the time of testing, and had no upper respiratory tract infections or allergies at the time of testing. Methods All subjects repeated /ma/ and “hamper” at normal pitch and loudness after an examiner model. Mean oral-nasal pressures, nasal airflow rates, and velopharyngeal orifice areas were calculated for each subject's utterances. A discriminate function analysis determined whether data could be grouped by age and sex. Results Significant differences in mean data for age groups of 5 to 9 years, 10 to 13 years, and 14 to 18 years were observed. Data showed decreases in pressures and increases in nasal airflow and orifice areas with age. Variability in pressure stayed consistent or decreased with age, but variability in nasal airflow and orifice areas increased with age. Conclusions We propose a scheme for categorizing velopharyngeal function for oral and nasal sound production to be used in clinical testing.

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Romano, Francesco, Samanta Milani, Roberto Ricci i Cesare Maria Joppolo. "Operating Theatre Ventilation Systems and Their Performance in Contamination Control: “At Rest” and “In Operation” Particle and Microbial Measurements Made in an Italian Large and Multi-Year Inspection Campaign". International Journal of Environmental Research and Public Health 17, nr 19 (5.10.2020): 7275. http://dx.doi.org/10.3390/ijerph17197275.

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In Operating Theatres (OT), the ventilation system plays an important role in controlling airborne contamination and reducing the risks of Surgical Site Infections (SSIs). The air cleanliness is really crucial in this field and different measurements are used in order to characterize the situation in terms of both airborne microbiological pollutants and particle size and concentration. Although the ventilation systems and airborne contamination are strictly linked, different air diffusion schemes (in particular, the Partial Unidirectional Airflow, P-UDAF, and the Mixing Airflow, MAF) and various design parameters are used, and there is still no consensus on real performance and optimum solutions. This study presents measurements procedures and results obtained during Inspection and Periodic Performance Testing (1228 observations) in a large sample of Italian OTs (175 OTs in 31 Italian hospitals) in their operative life (period from 2010 to 2018). The inspections were made after a cleaning procedure, both in “at-rest” conditions and “in operation” state. Inert and microbial contamination data (in air and on surfaces) are analyzed and commented according to four relevant air diffusion schemes and design classes. Related data on Recovery Time (RT) and personnel presence were picked up and are commented. The results confirm that the ventilation systems are able to maintain the targeted performance levels in the OT operative life. However, they attest that significant differences in real OT contamination control capabilities do exist and could be ascribed to various design choices and to different operation and maintenance practices. The study shows and confirms that the air diffusion scheme and the design airflow rate are critical factors. Beside large variations in measurements, the performance values, in terms of control of airborne particle and microbial contamination (in air and on surfaces), for P-UDAF systems are better than those that were assessed for the MAF air diffusion solution. The average performances do increase with increasing airflows, and the results offer a better insight on this relationship leading to some possible optimization.

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Chinchella, Enrico, Arianna Cauteruccio, Mattia Stagnaro i Luca G. Lanza. "Investigation of the Wind-Induced Airflow Pattern Near the Thies LPM Precipitation Gauge". Sensors 21, nr 14 (17.07.2021): 4880. http://dx.doi.org/10.3390/s21144880.

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The airflow velocity pattern generated by a widely used non-catching precipitation gauge (the Thies laser precipitation monitor or LPM) when immersed in a wind field is investigated using computational fluid dynamics (CFD). The simulation numerically solves the unsteady Reynolds-averaged Navier–Stokes (URANS) equations and the setup is validated against dedicated wind tunnel measurements. The adopted k-ω shear stress transport (SST) turbulence model closely reproduces the flow pattern generated by the complex, non-axisymmetric outer geometry of the instrument. The airflow pattern near the measuring area varies with the wind direction, the most intense recirculating flow and turbulence being observed when the wind blows from the back of the instrument. Quantitative parameters are used to discuss the magnitude of the airflow perturbations with respect to the ideal configuration where the instrument is transparent to the wind. The generated airflow pattern is expected to induce some bias in operational measurements, especially in strong wind conditions. The proposed numerical simulation framework provides a basis to develop correction curves for the wind-induced bias of non-catching gauges, as a function of the undisturbed wind speed and direction.

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Gendelis, S., i A. Jakovičs. "Numerical Modelling of Airflow and Temperature Distribution in a Living Room with Different Heat Exchange Conditions". Latvian Journal of Physics and Technical Sciences 47, nr 4 (1.01.2010): 27–43. http://dx.doi.org/10.2478/v10047-010-0016-z.

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Numerical Modelling of Airflow and Temperature Distribution in a Living Room with Different Heat Exchange ConditionsNumerical 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.

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Markov, Detelin, Nikolay Ivanov, George Pichurov, Marina Zasimova, Peter Stankov, Evgueni Smirnov, Iskra Simova, Vladimir Ris, Radostina A. Angelova i Rositsa Velichkova. "On the Procedure of Draught Rate Assessment in Indoor Spaces". Applied Sciences 10, nr 15 (22.07.2020): 5036. http://dx.doi.org/10.3390/app10155036.

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The objective of the paper is to demonstrate the importance of the unsteady Computational Fluid Dynamics (CFD) simulations and long-term measurements for the reliable assessment of thermal comfort indoors, for proper categorization of the indoor thermal environment and for identifying the reasons for complaints due to draught discomfort. Numerical simulations and experimental measurements were applied in combination to study ventilation in a field laboratory, a university classroom with a controlled indoor environment. Strong unsteadiness of the airflow was registered both in the unsteady RANS results and the real-scale long-term velocity data measured with thermo anemometer. Low-frequency high-amplitude velocity fluctuations observed lead to substantial time variation of the draught rate. In case of categorization of a thermal environment, the point measurements or steady-state RANS computations would lead to wrong conclusions as well as they cannot be used for identification of the reasons for people’s complaints due to draught discomfort if strong unsteadiness of the airflow exists. It is demonstrated that the length of the time interval for draught rate (DR) assessment may not be universal if low-frequency high-amplitude pulsations are present in the room airflow.

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Verneuil, Andrew, Bruce R. Gerratt, David A. Berry, Ming Ye, Jody Kreiman i Gerald S. Berke. "Modeling Measured Glottal Volume Velocity Waveforms". Annals of Otology, Rhinology & Laryngology 112, nr 2 (luty 2003): 120–31. http://dx.doi.org/10.1177/000348940311200204.

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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.

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Xu, Zhanyang, Wenhe Liu, Tieliang Wang, Wei Yu i Yuqing Zhang. "Simulation of Airflow in the Burning Cave of an Auxiliary Heating System in a Greenhouse". Transactions of the ASABE 61, nr 4 (2018): 1405–16. http://dx.doi.org/10.13031/trans.12719.

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Abstract. In this study, numerical simulations of airflow were carried out in the burning cave of an auxiliary heating system. Experimental measurements were also conducted to verify the performance of the numerical model, and turbulent airflow in the burning cave was considered. The numerical simulation in the burning cave was performed for three cases:(1) with a baffle at the bottom of the burning cave entrance, (2) without a baffle at the burning cave entrance, and (3) with a baffle at the top of the burning cave entrance. The turbulent airflow was modeled using the realizable k-e turbulence model as well as the non-equilibrium wall function. The airflow velocity was assessed in the burning cave, and some suggestions were given to improve the performance of the burning cave. The results showed that the airflow entering the burning cave differed due to different positions of the baffle. The smoldering combustion was more even and the burning rate could be controlled more easily when the baffle was placed at the top of the burning cave entrance, making the airflow enter the burning cave through the bottom of the baffle. The results also showed that the maximum airflow velocity in the burning cave increased with increased distance between the baffle and the bottom of the burning cave. Keywords: Airflow, Burning cave, Greenhouse, Simulation.

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Wang, Fujen, Yishun Huang i BowoYuli Prasetyo. "Energy-Efficient Improvement Approaches through Numerical Simulation and Field Measurement for a Data Center". Energies 12, nr 14 (18.07.2019): 2757. http://dx.doi.org/10.3390/en12142757.

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The power density of electronic equipment increased dramatically recently. Data center and data processing and telecommunication facilities are facing the exceptionally high sensible heat loads which result in a large amount of energy consumption. In this study, a numerical simulation using computational fluid dynamics (CFD) was conducted to investigate the influence of alternative approaches to avoid bypassing and recirculation for air distribution in a full-scale data center. Field measurements were extensively conducted to validate the simulation results. Various performance indexes were adopted to enhance the evaluation of the thermal performance of the data center. The simulation results revealed that the practice with hot aisle enclosure and the installation of blocking panels for the unoccupied racks can provide satisfactory airflow distribution and thermal management under low load conditions. The return temperature index (RTI) can be improved by 3% through CFD simulation through installation of the blank panels, which reveals the reduction of recirculation airflow. The return heat index (RHI) increases by 8%, which presents a reduction of bypass airflow. A practical experiment using physical air curtains was conducted to enclose the hot aisle in the data center, which also reveals an 8% improvement for bypass airflow. Higher cooling performance can be achieved via reduction of recirculation and bypass airflow in the data center. Through the simulation of different improvement approaches in the data center, the optimum practice for cooling airflow arrangement can be identified accordingly.

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