Relevant bibliographies by topics / Airflow

Academic literature on the topic 'Airflow'

Author: Grafiati
Published: 4 June 2021
Last updated: 6 September 2023

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Journal articles on the topic "Airflow"

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Jing, Jiajun, Dong-Seok Lee, Jaewan Joe, Eui-Jong Kim, Young-Hum Cho, and Jae-Hun Jo. "A Visualized Method of Airflow between Adjacent Zones inside a Multizone Building Based on Pressure Difference Frequency: Airflow Mapping." Indoor Air 2023 (July 3, 2023): 1–19. http://dx.doi.org/10.1155/2023/5433093.

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The airflow movement inside a multizone building has a significant impact on pollutant transfer, thermal comfort, and indoor air quality. However, there are difficulties in visualizing the airflow movement with existing methods. This study proposes a visualization method for evaluating airflows between adjacent internal zones inside a multizone building based on the analysis of pressure difference frequency. After the distribution of absolute pressure is measured and the wind pressures on the surfaces of the building are calculated, the variation of pressure differences between each couple of adjacent zones is analyzed for three levels: greater than 0 Pa, equal to 0 Pa, and less than 0 Pa (for any given zones selected as target zones). Finally, an airflow mapping is created for each floor using the visNetwork tool based on the R language. A target building was selected for applying the proposed method. The airflow mappings were derived from a detailed analysis of the pressure difference frequency between each couple of adjacent zones, presenting the variations of airflow direction and the dominant airflow during the measurement period in a visualized form. For example, the airflow direction from 1F_Z2 to 1F_Z3 is 92.0%. The spatial similarity in the variations of the airflow directions can also be observed on certain floors. The results of this experimental study show that the airflows between multiple zones can be easily identified without a complex building zone analysis. The variation in internal airflow direction between adjacent zones can be intuitively visualized, providing insight to the airtightness levels of building components. It is also observed that the airflow rates computed based on the airflow mappings can provide more guidance for the control of HVAC systems.
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Shirozu, Kazuhiro, Tetsuya Kai, Hidekazu Setoguchi, Nobuyasu Ayagaki, and Sumio Hoka. "Effects of Forced Air Warming on Airflow around the Operating Table." Anesthesiology 128, no. 1 (January 1, 2018): 79–84. http://dx.doi.org/10.1097/aln.0000000000001929.

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Abstract Background 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. Methods 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. Results 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. Conclusions 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.
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Wang, Ping, Kai Gu, Jinyi Hou, and Bingjie Dou. "An Automatic Recognition Method for Airflow Field Structures of Convective Systems Based on Single Doppler Radar Data." Atmosphere 11, no. 2 (January 27, 2020): 142. http://dx.doi.org/10.3390/atmos11020142.

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Airflow structures within convective systems are important predictors of damaging convective disasters. To automatically recognize different kinds of airflow structures (the convergence, divergence, cyclonic rotation, and anticyclonic rotation) within convective systems, an airflow structure recognition method is proposed, in this paper, based on a regular hexagonal template. On the basis of single Doppler radar data, the template is designed according to the appearance model of airflows in radial velocity maps. The proposed method is able to output types and intensities of airflow structures within convective systems. In addition, the outputs of the proposed method are integrated into a projection map of the airflow field structure types and intensities (PMAFSTI), which is developed in this work to visualize three-dimensional airflow structures within convective cells. The proposed airflow structure automatic recognition method and the PMAFSTI were tested using three typical cases. Results of the tests suggest the following: (1) At different evolution stages of the convective systems, e.g., growth, split, and dissipation, the three-dimensional distribution of the airflow fields within convective systems could be clearly observed through the PMAFSTI and (2) on the basis of recognizing the structures of the airflow field, the complex airflow field, such as a squall line, could be further divided into several small parts making the analysis of convective systems more scientific and elaborate.
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Lestinen, Sami, Mark Wesseling, Risto Kosonen, Hannu Koskela, and Dirk Müller. "Airflow characteristics under planar opposed ventilation jets in a controlled indoor environment." E3S Web of Conferences 111 (2019): 01029. http://dx.doi.org/10.1051/e3sconf/201911101029.

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Healthy, comfortable and intelligent indoor environment is a key objective in comprehensive well-being. This is also a main target of advanced HVAC-technology. In indoor environments, air distribution plays a major role while providing clean air to occupants. Therefore, investigating ventilation jets is an essential matter. In this study, the main objective was to improve knowledge on numerical modeling and airflow characteristics. In addition, the reliability of modeling methods were investigated. The experiments were carried out in a test room by using omnidirectional anemometers. The planar air jets were supplied below the ceiling from the opposite long-side walls. The exhaust openings were correspondingly near the floor. Isothermal and incompressible viscous airflow was simulated by using RANS, URANS, DES (SST-k-ω - LES) and SBES (SST-k-ω - LES) methods. The results show that modeling method has considerable effects on the predicted airflow field. However, the study indicates that correctly implemented numerical modeling may predict well the averaged airflow characteristics. Furthermore, the unsteady simulation allows airflows to fluctuate reasonably. In addition, SBES and DES methods were more sensitive in generating the airflow fluctuations than URANS. A recommendation is to carefully test and choose a modeling method for indoor airflows.
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De Vogeleer, Gerlinde, Peter Demeyer, Philippe Van Overbeke, and Jan G. Pieters. "Assessing Airflow Distribution in Vents of a Naturally Ventilated Test Facility Using Reference Air Velocity Measurements." Transactions of the ASABE 61, no. 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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Yamamoto, Toshiaki, Robert Donovan, and David Ensor. "Model Study for Optimization of Cleanroom Airflows." Journal of the IEST 31, no. 6 (November 1, 1988): 24–29. http://dx.doi.org/10.17764/jiet.1.31.6.et0013l4g2678g46.

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A menu-driven numerical simulation was developed to model the airflow in a typical industrial process cleanroom. The effects of changing entry velocity, isolating curtain height, and return airflow are evaluated. Theoretical guidelines for minimizing the strength of recirculation zones and optimizing the airflows in the cleanroom are discussed. These simulations help identify cleanroom designs that minimize the transport of particle contamination.
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Liu, Mingsheng. "Variable Speed Drive Volumetric Tracking for Airflow Control in Variable Air Volume Systems." Journal of Solar Energy Engineering 125, no. 3 (August 1, 2003): 318–23. http://dx.doi.org/10.1115/1.1559168.

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An airflow control method has been developed for variable air volume (VAV) systems. This airflow control method is termed VSD volumetric tracking (VSDVT) since both the supply and return airflows are determined using signals of variable speed drives (VSD) instead of flow stations. Its performance is studied and compared with the fan tracking (FT) method using model simulations. For the simulation considered, the VSDVT maintains a constant building pressure and the required outside airflow under all load conditions, and reduces the annual supply and return air fan energy significantly. This paper presents the VSDVT method, the system models, and the simulation results.
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Bulińska, Anna, and Zbigniew Buliński. "Determination of the Interzonal Airflows in Naturally Ventilated Dwellings Based on Concentration Measurements of the Metabolic Carbon Dioxide." Energies 16, no. 1 (December 21, 2022): 95. http://dx.doi.org/10.3390/en16010095.

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The role of interzonal airflows is especially pronounced in naturally ventilated buildings. In such buildings, reversed airflows in the ventilation stacks might occur as well. This affects the air exchange rate and contaminant distribution in buildings. A significant increase in carbon dioxide concentration is a characteristic phenomenon for poorly ventilated rooms. This paper demonstrates the application of metabolic carbon dioxide concentration measurements for interzonal airflow estimation in naturally ventilated buildings. The presented method is based on the continuous measurements of CO2 concentration at one point in each zone. These measurements are used to estimate airflow pattern in a multizone building by applying an inverse analysis. The developed methodology employs an iterative Levenberg-Marquardt procedure to maximise the nonlinear likelihood function. The validity of the method was verified against measurements carried out in a single naturally ventilated room. Further, the method was applied to calculate the airflow pattern in two apartments in Poland, containing 4 and 6 zones. The obtained results revealed very poor ventilation in both investigated apartments and reversed airflow in exhaust ducts. The amount of fresh air entering the rooms was insufficient to ensure good indoor air quality. The developed methodology can be effectively used as a diagnostic tool to identify the potential problems with ventilation systems.
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Wang, Yuanchen, Christian Lodroner, Michael Müller, and Konstantinos Stergiaropoulos. "Monitoring of Indoor Airflows with a New Two-Dimensional Airflow Sensor." E3S Web of Conferences 111 (2019): 05005. http://dx.doi.org/10.1051/e3sconf/201911105005.

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Although airflow is invisible, it has a big influence on the indoor environment. An incorrectly planned HVAC systems can lead to draught and thermal discomfort in occupied zones. Since the commissioning tests required after the installation of HVAC systems are generally performed without occupancy, the tests results do not always accurately represent the airflow that occurs during ordinary usage. The airflow needs to be continuously monitored and controlled by an intelligent HVAC system. The aim of this study is to develop a new two-dimensional airflow sensor for the monitoring of indoor airflow, which can also indicate the flow direction. Several of these sensors can be placed in a planar sensor array, by which a two-dimensional section of the flow field is created. By recording data from several of these arrays simultaneously, an image of the three-dimensional flow could be acquired. The prototype of the sensor, which is made by Hahn-Schickard Society for Applied Research is currently being validated at the Institute for Building Energetics, Thermotechnology and Energy Storage. When the development is completed, it will greatly contribute to the control strategies of HVAC systems.
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Lei, Yao, and Mingxin Cheng. "Aerodynamic Performance of Hex-Rotor UAV Considering the Horizontal Airflow." Applied Sciences 9, no. 22 (November 9, 2019): 4797. http://dx.doi.org/10.3390/app9224797.

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In this paper, the aerodynamic performance of a Hex-rotor unmanned aerial vehicle (UAV) with different rotational speeds (1500–2300 RPM) considering the horizontal airflow conditions is analyzed by both simulations and experiments. A low-speed wind tunnel experiments platform is applied to measure the thrust, torque, and power consumption of a Hex-rotor UAV with different rotational speeds in horizontal airflow, which varied from 0 m/s–4 m/s. First, this paper introduces the effect of horizontal airflow on a UAV. Then, the low-speed wind tunnel experiments were carried out on a Hex-rotor UAV (D/L = 0.56) with different horizontal velocities to determine the hover performance. Finally, numerical simulations were obtained with the streamline distributions, pressure distributions, velocity contour, and vortex distributions at different horizontal airflow conditions to describe the aerodynamic interference effect of different horizontal airflows. Combined with the experimental results and numerical simulations results, the horizontal airflow proved to have a significant influence on the aerodynamic performance of the Hex-rotor UAV with an increase in thrust and power. Indeed, the streamlines in the flow field were coupled to each other at the presence of the incoming airflow. Especially when the incoming airflow was larger, the Hex-rotor UAV could properly use low-speed flight to maintain high power loading. Finally, it is inferred that the aerodynamic performance of the Hex-rotor UAV is also related to the movement and deformation of the vortex at the tip of the rotor.
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Dissertations / Theses on the topic "Airflow"

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Seidel, Robin. "Mechanical dynamic response of airflow sensors of airflow sensors of crickets." Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493806.

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Insects have evolved very elaborate sensing systems. The airflow sensors of crickets are among the most sensitive sensors in the animal world. The sensor comprises a thin hair, which protrudes from the surface of the cuticle and sits in a specialised socket. Its elliptical base is surrounded by a flexible joint membrane to allow the hair to rotate. The polarity of the base restricts the rotation of the hair to a preferred plane of movement. The results of the morphometric analysis of the airflow sensors presented in this study show that the maximal diameter of the hair is a strong predictor for the other parameters determining the sensors geometry, such as the hair length, its socket geometry, as well as the hair's elliptical base, which is otherwise hidden within the socket and out of view unless the hair and its base are removed.
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Solaymani-Kohal, Jamshid. "Airflow through horizontal openings." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294525.

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Jaroslawski, ML. "Airflow limitation in croup." Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/26628.

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This thesis investigates a mechanism for air flow limitation in children with croup. Croup is a common condition affecting many young children. Infection (usually viral) causes swelling of the mucosa in the subglottic region of the airway with consequent narrowing of the airway. Although researchers have investigated croup for the past sixty years, there is still very little information available on how croup affects air flow dynamics. The current theory assumes that the stenosis formed by croup in the subglottis of infants leads to a dynamic collapse of the extrathoracic trachea (Chernick, 1990). According to this literature, the dynamic collapse of the extrathoracic trachea will limit the inspiratory flow. It was believed that in severe cases of croup, the dynamic collapse may even temporarily block the airways. In order to investigate the mechanism for air flow limitation in croup the author used the intrathoracic pressure - flow traces from twenty patients with croup, four patients who had been intubated for croup and five normal subjects. Laryngeal X-rays from another twenty patients with croup were analysed as well as five videos, made during laryngoscopy, of the subglottic cross-sectional area of an additional five patients with croup requiring intubation. All data used in this project was collected by an experienced paediatrician from the Red Cross War Memorial Children's Hospital who is also the supervisor of this thesis. Both the video and the X-ray data showed that the dynamic collapse of the trachea contributes much less to airflow obstruction than the subglottic swelling itself. The hypothesis investigated in this thesis is that air flow becomes restricted due to wave speed limitation. According to the theory of wave speed limitation, an increase in driving pressure (the intrathoracic pressure) does not increase the flow if the speed of the air particles exceeds the wave speed. In our case the wave speed is the speed of sound within the lumen of the compliant, narrowed airway. In order to test that theory, it was necessary to obtain the flow, the driving pressure in the subglottis and the cross-sectional area of the subglottis of patients with croup. Unfortunately, the measurement of subglottal cross-sectional areas from videos made during laryngoscopies, proved to be impossible due to both ethical and practical constraints. The measurement of the subglottal cross-sectional areas from X-rays was also difficult in practice. Therefore, the cross-sectional area is calculated. The general orifice equation is modified m order to calculate the subglottal cross-sectional areas in patients with croup. Two methods are used to test the hypothesis of wave speed limitation: i) The wave speed limitation formula. The wave speed limitation formula directly calculates the maximum flow from the pressure - flow data. Hereafter the calculated maximum flow is compared with the measured flow. ii) A lumped component model. A nonlinear, lumped component model has been used to calculate the flow from the driving pressure (intrathoracic pressure). Flow is not limited in this model and an increase in driving pressure will result in a corresponding increase in flow. The flow which is calculated using this model has also been compared to the measured flow. It was found that, in children with croup, there is a good correlation (r=0.82) between calculated and measured values of maximum flow using the wave speed limitation model. The slope of the linear fit using a least square's approximation is 0.98 and this linear relationship is valid for a 0.05 level of significance for Conover's nonparametric test (Daniel and Terrell, 1989). The lumped component model was able to fit the inspiratory flow data with a small sum of square error in the case of both normal ((7.56 ± 0.86) · 10⁻⁹ (ml/s)²) and intubated patients ((3.2 ± 0.75)·10⁻⁹ (ml/s)²). However, the error rose dramatically in patients with croup ((2.04 ± 0.5) -10⁻⁸ (ml/s)²) thus indicating that the lumped component model is no longer valid in these patients. It is concluded that the measured flow velocities in patients with croup approach the calculated velocity of sound in the region of the subglottic swelling, and that the wave speed theory accurately describes the flow limitation. Further support of this is the fact that the lumped component model, which does not incorporate a flow limiting mechanism, breaks down in patients with croup.
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Abedi, Milad. "Directional Airflow for HVAC Systems." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/88524.

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Directional airflow has been utilized to enable targeted air conditioning in cars and airplanes for many years, where the occupants could adjust the direction of flow. In the building sector however, HVAC systems are usually equipped with stationary diffusors that can only supply the air either in the form of diffusion or with fixed direction to the room in which they have been installed. In the present thesis, the possibility of adopting directional airflow in lieu of the conventional uniform diffusors has been investigated. The potential benefits of such a modification in control capabilities of the HVAC system in terms of improvements in the overall occupant thermal comfort and energy consumption of the HVAC system have been investigated via a simulation study and an experimental study. In the simulation study, an average of 59% per cycle reduction was achieved in the energy consumption. The reduction in the required duration of airflow (proportional to energy consumption) in the experimental study was 64% per cycle. The feasibility of autonomous control of the directional airflow, has been studied in a simulation experiment by utilizing the Reinforcement Learning algorithm which is an artificial intelligence approach that facilitates autonomous control in unknown environments. In order to demonstrate the feasibility of enabling the existing HVAC systems to control the direction of airflow, a device (called active diffusor) was designed and prototyped. The active diffusor successfully replaced the existing uniform diffusor and was able to effectively target the occupant positions by accurately directing the airflow jet to the desired positions.
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The notion of adjustable direction of airflow has been used in the car industry and airplanes for decades, enabling the users to manually adjust the direction of airflow to their satisfaction. However, in the building the introduction of the incoming airflow to the environment of the room is achieved either by non-adjustable uniform diffusors, aiming to condition the air in the environment in a homogeneous manner. In the present thesis, the possibility of adopting directional airflow in place of the conventional uniform diffusors has been investigated. The potential benefits of such a modification in control capabilities of the HVAC system in terms of improvements in the overall occupant thermal comfort and energy consumption of the HVAC system have been investigated via a simulation study and an experimental study. In the simulation study, an average of 59% per cycle reduction was achieved in the energy consumption. The reduction in the required duration of airflow (proportional to energy consumption) in the experimental study was 64% per cycle on average. The feasibility of autonomous control of the directional airflow, has been studied in a simulation experiment by utilizing the Reinforcement Learning algorithm which is an artificial intelligence approach that facilitates autonomous control in unknown environments. In order to demonstrate the feasibility of enabling the existing HVAC systems to control the direction of airflow, a device (called active diffusor) was designed and prototyped. The active diffusor successfully replaced the existing uniform diffusor and was able to effectively target the occupant positions by accurately directing the airflow jet to the desired positions.
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Fung, Chak Fai. "The structure of airflow over waves." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409924.

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Baddock, Matthew. "Airflow dynamics in transverse dune interdunes." Thesis, University of Northampton, 2005. http://nectar.northampton.ac.uk/2994/.

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Aeolian dune interdunes have been relatively ignored when compared with the research attention on the morphodynamics of the dune bodies themselves. This neglect is in spite of the possible significance of interdune dynamics for the geomorphology of the sand dune system as a whole, especially with regard to dune spacing. This project involved the collection of geomorphologically relevant airflow data for four relatively simple transverse dune interdunes. The study locations were chosen in order to sample interdunes with different size and surface type characteristics, the dynamics of which were investigated for when incident flow was normal to the upwind crest. The findings confirm existing models of aeolian dune lee-side flow in terms of flow re-attachment length and recovery attributes. A consistent pattern of increasing near-surface velocity downwind of re-attachment provides a mechanism for interdunes as sand-free features. Where studies for comparison from other aeolian examples are limited, the field-measured turbulence shows the importance of the shear layer as a source of turbulence, and agrees with studies from subaqueous bedforms. The importance of shear stress variability and the possible contribution of turbulence structures to the maintenance of sediment transport at re-attachment where velocity and mean stress is low or negative is also emphasised. At the downwind edge of interdunes, the mean and turbulent velocity properties, and therefore morphodynamics, vary according to the interdune size. In this case, interdune length leads to greater recovery, and a balance exists in this region between the recovering flow at the surface, dissipating wake from above and the obstacle effect of the dune. The flow dynamics are characterised for the different types of interdune observed. Dynamics accordant with the flow response model are seen to characterise the interdune setting with the closest spacing. The occurrence of other “extended” aeolian interdunes with a length well over that for flow separation demanded the development of a new descriptive model to characterise the dynamics therein. In this model, the variation in near-surface flow allowed process zones to be identified through the interdune. The geomorphological significance of the processes dominating each zone are discussed and comparisons are made between the flow response case and the new interdune model from this study
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Rennie, Catherine. "Investigation of sinonasal airflow and transport." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/23889.

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This work comprises an investigation of airflow and transport in the human upper airways, which not only perform essential air conditioning physiological functions (heat and water exchange and primary filtration) but also house the olfactory receptors. The conflicting requirements posed by efficient air transit on the one hand and sampling for olfaction on the other renders the geometry of the upper airways complex. Knowledge of the geometry and flow conditions are primary requirements for understanding the physiological mechanics of the airways. This work describes the application of imaging and experimental measurement techniques to determine the variations in nasal airway geometry and the characteristics of nasal inspiratory flow. Whilst the results are relevant to a host of applications, the particular case of sinonasal ventilation well illustrates the interrelation between form, flow and function as well as motivating the development of improved techniques for clinical management. Specifically 3T MR imaging has been investigated as a means to define the anatomy in congested and decongested states. Results show very large changes in nasal airway calibre and moreover allow the variation in mucosal engorgement throughout the nasal cavity to be mapped. Highly time resolved hot wire measurements of inspiratory flow profiles revealed for the first time the rapid temporal development of inspiratory flow during normal inspiration and dramatically so during sniffing. Variations in flow profile were recorded across a cohort of subjects for conditions of normal inspiration, sniffing and smelling. Sinonasal gas exchange is of particular interest given the common occurrence of sinus pathologies. Here short half-life Krypton imaging has been used to investigate gas exchange between the maxillary sinus and the nasal cavity. It has been shown that the technique can provide quantitative assessment of volume flow rate in a model, demonstrating the rapid venting associated with an accessory ostium.
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Bates, Alister. "Mechanics of airflow in human inhalation." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25515.

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The mechanics of airflow in the large airways during inspiration affects important physiological functions such as ventilation, olfaction, heat exchange and mass transfer. The behaviour of the airflow is important not only for healthcare applications including diagnosis, intervention planning and assessment, but for inhalation toxicology. This research aims to further the understanding of human nasal physiology through computational modelling. Specifically, the effects of transient inhalation conditions on flow dynamics and transport were characterised and the changes in flow behaviour in response to certain pathologies quantified. The key findings can be summarised as follows: Firstly, the time scales for airflow in the large airways have been identified and the initial flow patterns revealed. Three phases in the temporal behaviour of the flow were identified (flow initiation, quasi-equilibrium and decay). The duration of each phase differs depending on the quantity of interest. Flow in the nose was characterised as transitional, whilst in parts of the descending airways it is turbulent, particularly in the faster moving regions around the jets which may occur in the pharynx, larynx and at the superior end of the trachea. The bulk of the flow is biased to fill only certain regions of the airways, whilst other regions carry little flow, due to features upstream. Analysis of cross-sectional images provided by medical imaging does not necessarily provide a representative view of the area available to the flow. Various scalar species were employed to represent the fate of nanoparticles and gaseous species within the airways. Only species with high diffusion rates exhibited significant absorption at the airway walls. Airway pathologies often cause changes to the geometry of the airway. One such pathology, the goitre, was found to curve the trachea and in some cases cause constriction. Both these geometric changes were found to increase the pressure loss and energy required to drive flow through the trachea. Furthermore, the flow in pathological cases was more disturbed. High resolution simulations have been used to address these topics and the scales simulated have been analysed in terms of the smallest features possible in the flow to determine their fidelity.
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Odewole, Gboyega Akindeji. "Airflow patterns in ventilated wall cavities." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/airflow-patterns-in-ventilated-wall-cavities(f67d5b52-af96-4784-a1ac-6d6c3c41812e).html.

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Though heating, insulation, wall claddings and cavity-wall construction are considered as measures for remediating moisture and condensation in buildings, ventilation of wall cavities has however become a mantra among architects and other building professionals. Holes of any size and shape are made and located on building facades based on the accepted wisdom that a little air movement will keep the wall cavities dry. Whilst ventilation has been found to be successful in the control of moisture and condensation in rooms and larger enclosures, there is however insufficient understanding of how it works in thin spaces with high aspect ratios, such as the wall cavities studied in this thesis.In order to put in place good control and management practices in the remediation of moisture and condensation in vertical wall cavities by natural ventilation, it is vital to understand the dynamics of airflow in these cavities. In this thesis therefore, different size and shape of slots were employed to numerically investigate the effects of size, spacing and number of the slots on the characteristics of the velocity fields (patterns of airflow and distributions of velocity) in different cavity models. The Reynolds-Averaged-Navier-Stokes (RANS) methodology was employed to simulate the cavity flows under different modelling conditions using FLUENT. The BS 5925 model, an empirical relation for predicting ventilation rates in rooms and other larger enclosures, was employed and modified to predict ventilation rates in these cavities. Experimentally, the mapping of the airstreams in these cavities was obtained under similar reference (inlet) wind speeds employed for the numerical investigations.The results of this study show that there exists a potential at higher wind speeds for natural ventilation in the remediation of moisture and condensation in the cavities of vertical walls. The steady state approach employed in the RANS-based computation of cavity flows in this thesis averages out the peak values of air velocities and therefore gives no information about regions of maxima or minima velocity values even at higher wind speeds. This makes the predicted air change rates insensitive to the inlet air velocities from the ventilation slots and therefore makes the results more applicable for long term control and management of moisture in these cavities. In order to therefore put in place short, medium and long term plans for remediation of moisture in these wall cavities, a time-dependent computation is required. This will also allow the efficiency of the cavity ventilation to be properly assessed. Using the modified BS 5925 model, reasonable predictions were obtained for the air change rates of the wall cavities with the different size of ventilation slots employed. Close agreements are also obtained at lower and higher wind speeds between the predicted ventilation rates from the modified BS 5925 model and the experimental results employed as benchmark for validating the results.
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Rowell, Jeffrey. "Schlieren imaging : visualization of airflow in speech." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55103.

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Schlieren imaging is a non-invasive research tool that enables real-time visualization of airflow through refraction of light. Used predominantly in aerospace and ballistics research, its suitability for observing airflow in speech was proposed nearly 40 years ago. To date, this potential has been virtually unexplored. The following proof-of-concept study investigates the visual correlates of nasal versus non-nasal airflow to provide a preliminary demonstration of the tool’s ability to visualize aerodynamic events in speech. Simultaneous schlieren and audio recordings were made of three French nasal/non-nasal minimal pairs spoken by eight native-French speakers. These stimuli were presented to 10 raters in Video-only, Audio-only and Combined Audio-Visual formats. The raters coded each stimulus as either “nasal” or “not nasal”. Accurate designation of Video-only stimuli was significantly above chance response (p < .05), indicating that the difference between airflow for nasal and non-nasal sounds can be visualized and perceived through schlieren imaging alone. Non-significant improvements were observed over time in the Video-only condition. Differences between Combined Audio-Visual and Audio-only stimuli were non-significant and likely influenced by a ceiling effect for the auditory information presented in both conditions. Further research is needed with more difficult auditory-perceptual tasks to explore potential supplementary advantages of schlieren visual feedback alongside auditory ratings of resonance. Future research may also benefit from improved training procedures for schlieren imaging. Nonetheless, schlieren imaging has promising potential for future implementation in both speech research and clinical applications, particularly for speech resonance disorders.
Medicine, Faculty of
Audiology and Speech Sciences, School of
Graduate
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Books on the topic "Airflow"

1

Airflow. Hemel Hempstead: Nexus Special Interests, 1998.

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Lynn, Wray H., ed. Airflow in ducts. Hayward, CA: LAMA Books, 1996.

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Thurlbeck, William M. Chronic airflow obstruction. 2nd ed. Oxford: Blackwell Scientific, 1997.

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M, Thurlbeck William, Wright Joanne Lynne, and Thurlbeck William M, eds. Thurlbeck's chronic airflow obstruction. 2nd ed. Hamilton, Ont: B.C. Decker, 1999.

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L, Felker Travis, ed. Dampers and airflow control. Atlanta, Ga: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, 2009.

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Canada Mortgage and Housing Corporation., ed. CMHC garbage bag airflow test. [Ottawa]: Canada Mortgage and Housing Corporation, 2001.

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Baechtel, John. Practical engine airflow: Performance theory & application. North Branch, MN: CarTech, 2015.

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Transient airflow in building drainage systems. Abingdon, Oxon: Spon Press, 2010.

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Roulet, Claude-Alain. Airflow patterns within buildings: Measurement techniques... Coventry: Air Infiltration and Ventilation Centre, 1991.

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Swaffield, J. A. Transient airflow in building drainage systems. Abingdon, Oxon: Spon Press, 2010.

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Book chapters on the topic "Airflow"

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Singh, Pramod. "Airflow." In Learn PySpark, 67–84. Berkeley, CA: Apress, 2019. http://dx.doi.org/10.1007/978-1-4842-4961-1_4.

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Cheng, Hwee Ming. "Airflow." In Physiology Question-Based Learning, 51–59. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-12790-3_6.

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Littler, John, Saffa Riffat, and Mashhour Eid. "Interzone Airflow." In Solar Energy Applications to Buildings and Solar Radiation Data, 94–100. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-2961-6_10.

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Champion, Howard R., Nova L. Panebianco, Jan J. De Waele, Lewis J. Kaplan, Manu L. N. G. Malbrain, Annie L. Slaughter, Walter L. Biffl, et al. "Airflow Obstruction." In Encyclopedia of Intensive Care Medicine, 124. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-00418-6_1097.

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Beausoleil-Morrison, Ian. "Internal airflow." In Fundamentals of Building Performance Simulation, 117–23. New York : Routledge, 2020. I Includes bibliographical references and index.: Routledge, 2020. http://dx.doi.org/10.1201/9781003055273-9.

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Jones, James, and Demetri Telionis. "Forced Airflow." In Aeroform, 160–84. New York: Routledge, 2022. http://dx.doi.org/10.4324/9781003167761-7.

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Petty, Thomas L. "Chronic Airflow Obstruction." In Topics in Clinical Pharmacology and Therapeutics, 358–66. New York, NY: Springer New York, 1986. http://dx.doi.org/10.1007/978-1-4612-4864-4_18.

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Keey, Roger B., Timothy A. G. Langrish, and John C. F. Walker. "Airflow and Convection." In Kiln-Drying of Lumber, 203–19. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-642-59653-7_9.

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Ellison, Gordon N. "Thermodynamics of Airflow." In Thermal Computations for Electronics, 21–28. Second edition. | Boca Raton, FL : CRC Press/Taylor & Francis Group, 2020.: CRC Press, 2020. http://dx.doi.org/10.1201/9781003029328-2.

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Jones, James, and Demetri Telionis. "Wind and Airflow." In Aeroform, 37–79. New York: Routledge, 2022. http://dx.doi.org/10.4324/9781003167761-3.

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Conference papers on the topic "Airflow"

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Qin, Yongqiang, Chris J. Vincent, Nadia Bianchi-Berthouze, and Yuanchun Shi. "AirFlow." In CHI '14: CHI Conference on Human Factors in Computing Systems. New York, NY, USA: ACM, 2014. http://dx.doi.org/10.1145/2559206.2581309.

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E.M. Garlinski and D.D. Mann. "Airflow Characteristics through a Horizontal-Airflow Biofilter." In 2004, Ottawa, Canada August 1 - 4, 2004. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2004. http://dx.doi.org/10.13031/2013.16768.

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Baskar, Subramaniyan, and Sebastian Prince Arockia Doss. "Investigation on Underhood Airflow Management - Effect of Airflow Statistics." In International Conference on Advances in Design, Materials, Manufacturing and Surface Engineering for Mobility. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2018. http://dx.doi.org/10.4271/2018-28-0024.

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Ito, Kyoko, Yuta Tsuji, Hirotake Ishii, and Hiroshi Shimoda. "The Recovery Effect in Work Efficiency by Temporary Stimulative Airflow." In Intelligent Human Systems Integration (IHSI 2022) Integrating People and Intelligent Systems. AHFE International, 2022. http://dx.doi.org/10.54941/ahfe1001078.

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In this paper, we examined stimulative airflows to recover the arousal level and performance of office workers. First, two types of airflow were selected as candidates based on the results of preliminary experiments. Next, we conducted an experiment to verify the effects of these airflows. There are nine participants in the experiment and work efficiency was measured from their work performance. The airflows were exposed to detect a decrease in the arousal level of the participants. From the results, six participants were included in the analysis. We analyzed the results before and after exposure to the airflow using various physiological indicators.
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Linder, Stephen Paul, Jim Van Gilder, Yan Zhang, and Enda Barrett. "Dynamic Control of Airflow Balance in Data Centers." In ASME 2019 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ipack2019-6304.

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Abstract Efficient cooling of data center infrastructure is an important way to reduce total energy consumption. Containment, with separation of hot and cold airflows has allowed significant increase in efficiencies. However, balancing the airflow, so that IT equipment in an aisle only receives the cooling airflow that that aisle needs is still often not done. We propose a new architecture where IT racks are clustered together with shared hot aisles ducted to a common ceiling plenum. Each aisle has an actively controlled damper used to balance the airflow to the cooling infrastructure. Using a differential air pressure sensor in each aisle and an algorithm designed to balance the flow network, we minimize the cooling airflow and maximize cooling efficiency.
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Kargar, Alireza, Mohammad H. Hosni, Steve Eckels, and Tomas Gielda. "Experimental Analysis of an Air-to-Air Heat Exchanger for Use in a Refrigeration Brayton Cycle." In ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56544.

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The refrigeration Brayton cycle, which has been used extensively in various industries, has an excellent potential for use in automotive air conditioning applications. However, the air-cycle system has a couple of drawbacks including fog generation and low cycle efficiency. In this research project, an air-to-air heat exchanger called a ‘mixer’ is designed and used at the outlet of a refrigeration Brayton cycle. The primary function of the mixer is to remove moisture from the secondary warm airflow into the system. Successful moisture removal from the secondary airflow results in achieving the second function of fog dissipation from the primary cold airflow. In order for the system to perform appropriately, the moisture removal rate must be kept at the highest possible rate. The experimental results from this research project reveal that to enhance moisture removal rate, one may either increase the primary cold airflow rate, decrease the secondary warm airflow rate, or the combination of the above airflow adjustments. Furthermore, based on experimental results, one may speculate that there is an optimum point in decreasing the secondary airflow rate. However, in increasing the primary airflow rate, one must be aware of the pressure drop through the cold side of the mixer as the higher pressure drop results in higher power consumption for the Brayton cycle. It is important to point out that appropriate levels of the primary and secondary airflows impacts the mixer effectiveness, and that for a constant cold airflow rate, decreasing the warm airflow rate below the cold airflow rate results in higher effectiveness.
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Yuill, David P., Nathan K. Redmann, and Mingsheng Liu. "Development of a Fan Airflow Station for Airflow Control in VAV Systems." In ASME 2003 International Solar Energy Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/isec2003-44022.

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A fan airflow station has been developed by the authors. This station is used to determine fan airflow using fan speed and fan head as inputs. These inputs can be measured accurately in variable air volume (VAV) systems, so they can be used as a cost-effective control monitoring method for heating, ventilation and air conditioning (HVAC) systems. Theoretical models have been developed for the flow station using both second and third order relationships between the airflow and the inputs. The theoretical model has been experimentally tested and excellent agreement between the model and the experimental values was found. The second order model was within 1.71% of the experimental values, and the third order model was within 1.52%. The second order model, which is much simpler, is considered adequate for use in buildings.
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D D Mann, K N Wilson, and C S Ima. "Evaluation of Airflow through a Horizontal-Airflow Biofilter with a Non-Pressurized Headspace." In ASABE/CSBE North Central Intersectional Meeting. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2006. http://dx.doi.org/10.13031/2013.22356.

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Zheng, B., X. Pang, M. Liu, and I. Joo. "Using a Fan Air Flow Station to Control Building Static Pressure in a Variable Volume Air Conditioning System." In ASME 2005 International Solar Energy Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/isec2005-76215.

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A fan airflow station measures airflow through a fan using fan speed, fan head, and the field-calibrated fan curve. This paper presents the theory and techniques of using fan airflow station in a variable volume system for building pressure control. These techniques include fan curve calibration, determination of the volumetric flow difference of the supply and return airflows, and sensor locations. The return fan speed profiles were plotted, and data was collected on building pressure after implementing the fan air flow station. The Implementation of a fan air flow station demonstrates that the return fan speed can track the supply fan speed profile as building loads change, such that building pressure is maintained within a satisfactory range.
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Nguyen Minh-Dung, N., H. Takahashi, K. Kuwana, T. Takahata, K. Matsumoto, and I. Shimoyama. "3D airflow velocity vector sensor." In 2011 IEEE 24th International Conference on Micro Electro Mechanical Systems (MEMS 2011). IEEE, 2011. http://dx.doi.org/10.1109/memsys.2011.5734474.

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Reports on the topic "Airflow"

1

Lorenzetti, D. M. Assessing multizone airflow software. Office of Scientific and Technical Information (OSTI), December 2001. http://dx.doi.org/10.2172/795952.

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Caress, R. W., D. W. MacArthur, K. S. Allander, J. A. Bounds, M. M. Catlett, S. E. Garner, J. D. Johnson, J. P. Johnson, and D. A. Rutherford. LRAD-based airflow monitors. Office of Scientific and Technical Information (OSTI), March 1994. http://dx.doi.org/10.2172/10130984.

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Harrje, D. (Airflow patterns within buildings). Office of Scientific and Technical Information (OSTI), November 1989. http://dx.doi.org/10.2172/5452864.

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Winkler, Jonathan M., Scott G. Horowitz, Jason W. DeGraw, and Noel D. Merket. Evaluating EnergyPlus Airflow Network Model for Residential Ducts, Infiltration, and Interzonal Airflow. Office of Scientific and Technical Information (OSTI), October 2017. http://dx.doi.org/10.2172/1400370.

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Stratton, J. Chris, W. J. N. Turner, Craig P. Wray, and Iain S. Walker. Measuring Residential Ventilation System Airflows: Part 1 – Laboratory Evaluation of Airflow Meter Devices. Office of Scientific and Technical Information (OSTI), November 2012. http://dx.doi.org/10.2172/1168595.

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Stratton, J. Chris, W. J. N. Turner, Craig P. Wray, and Iain S. Walker. Measuring Residential Ventilation System Airflows: Part 1 – Laboratory Evaluation of Airflow Meter Devices. Office of Scientific and Technical Information (OSTI), November 2012. http://dx.doi.org/10.2172/1168596.

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Stokes, A. W., and G. Corbett. Airflow distributions in 9 east longwall. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1986. http://dx.doi.org/10.4095/304981.

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Biermayer, Peter J., James Lutz, and Alex Lekov. Measurement of airflow in residential furnaces. Office of Scientific and Technical Information (OSTI), January 2004. http://dx.doi.org/10.2172/826106.

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Fisk, William J., David Faulkner, Douglas P. Sullivan, and Woody Delp. Measuring rates of outdoor airflow into HVAC systems. Office of Scientific and Technical Information (OSTI), October 2002. http://dx.doi.org/10.2172/824629.

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Persily, Andrew K., and Elizabeth M. Ivy. Input data for multizone airflow and IAQ analysis. Gaithersburg, MD: National Institute of Standards and Technology, 2001. http://dx.doi.org/10.6028/nist.ir.6585.

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