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Jing, Jiajun, Dong-Seok Lee, Jaewan Joe, Eui-Jong Kim, Young-Hum Cho i 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 (3.07.2023): 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 i Sumio Hoka. "Effects of Forced Air Warming on Airflow around the Operating Table". Anesthesiology 128, nr 1 (1.01.2018): 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 i Bingjie Dou. "An Automatic Recognition Method for Airflow Field Structures of Convective Systems Based on Single Doppler Radar Data". Atmosphere 11, nr 2 (27.01.2020): 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 i 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 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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Yamamoto, Toshiaki, Robert Donovan i David Ensor. "Model Study for Optimization of Cleanroom Airflows". Journal of the IEST 31, nr 6 (1.11.1988): 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, nr 3 (1.08.2003): 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, i Zbigniew Buliński. "Determination of the Interzonal Airflows in Naturally Ventilated Dwellings Based on Concentration Measurements of the Metabolic Carbon Dioxide". Energies 16, nr 1 (21.12.2022): 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 i 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, i Mingxin Cheng. "Aerodynamic Performance of Hex-Rotor UAV Considering the Horizontal Airflow". Applied Sciences 9, nr 22 (9.11.2019): 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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Zhao, Wanying, Christopher Choi, Dapeng Li, Geqi Yan, Hao Li i Zhengxiang Shi. "Effects of Airspeed on the Respiratory Rate, Rectal Temperature, and Immunity Parameters of Dairy Calves Housed Individually in an Axial-Fan-Ventilated Barn". Animals 11, nr 2 (31.01.2021): 354. http://dx.doi.org/10.3390/ani11020354.
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At many modern dairy farms, calves raised in barns are kept in individual stalls separated by solid partitions, which act as barriers. Ventilation fans blowing air perpendicular to these stalls only provide the optimal airflow to the first few calves, while those further away receive a slower airflow. To ascertain whatever effects different airflow speeds may have on the health of animals kept in stalls located at increasing distances from ventilation fans, we divided a select group of 43 Holstein dairy calves into six subgroups based on age, and each subgroup was subjected to either a specified high-speed or low-speed airflow as follows: (1) Six 3-day-olds received high-speed airflow (D3-HA); (2) Six 3-day-olds received low-speed airflow (D3-LA); (3) Eight 19 (±3)-day-olds received high-speed airflow (D19-HA); (4) Eight 19 (± 3)-day-olds received low-speed airflow (D19-LA); (5) Eight 29 (±3)-day-olds received high-speed airflow (D29-HA); and (6) Seven 29 (±3)-day-olds received medium-speed airflow (D29-MA). These trials show that the rectal temperatures and respiratory rates of D19-LA (39.37 °C; 72.90 breaths/min) were significantly higher than those of D19-HA (39.14 °C; 61.57 breaths/min) (p ≤ 0.05), and those of D29-MA (39.40 °C; 75.52 breaths/min) were significantly higher than those of D29-HA (39.20 °C; 68.41 breaths/min) (p ≤ 0.05). At 33 (±3) days of age, those calves receiving high-speed airflow (p ≤ 0.05) registered significantly higher immunoglobulins A and M than calves receiving low-speed flow. Those calves subjected to a high-speed airflow also registered significantly lower tumor necrosis factor levels than those receiving low-speed flow (p ≤ 0.05). Among the 29 to 43-day-old calves, no significant differences in immunity parameters were found to exist between groups D29-HA and D29-MA. On the basis of these findings, we were able to conclude that in the warm season, when the calves were less than 0.5 months old, low-speed (0.17–0.18 m/s) airflows had no significant effect on calves; when the calves were 1 month old, low-speed airflow (0.20–0.21 m/s) may impair the immune functions; when the calves were 1 to 1.5 months old, the airflow velocity higher than 0.9 m/s can meet the needs of the calf without a negative impact on the calf.
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Fu, Xiu Zhang, i Jian Dong. "Numerical Analysis on the Impact of Windows and Interior Doors on Indoor Airflow of Rural Residence". Applied Mechanics and Materials 548-549 (kwiecień 2014): 1683–88. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.1683.
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There are several factors impacting on the indoor airflows, such as building openings, ambient wind speed, occupants’ behavior and so forth. This paper concentrates on the impact of windows and interior doors on airflows in a rural multi-storey residential building. The indoor airflow simulation was carried out by using the CFD software. 3 states of interior doors were set, and 60 regions were arrayed in bedroom to observe the variation of airflows. According to data of regions, the uniformity of airflow and the thermal comfort were analyzed. Simulation results identified that closing interior doors will increase the mean age of indoor air about 7 times as it under the condition of opening doors, which is from 90s to 666s. It also shows that transom windows is beneficial to improve natural ventilation efficiency, as it can raise the average wind velocity by 40% when interior doors are closed.
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Zhu, Jialiang, Lihui Wang, Zhiling Li, Jianan Ma, Changjiang Ma i Xinwei Yang. "Simulation study on the dynamic velocity field of the supplying jet coupled with the platform piston wind in non-screen door subway stations". E3S Web of Conferences 356 (2022): 02037. http://dx.doi.org/10.1051/e3sconf/202235602037.
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The coupling airflows of platform piston wind and station air-conditioning supply air is the most typical airflow organization of non-screen door subway station platform. By establishing a CFD software model of the coupling process between piston wind and air-conditioning supply air in subway station platform, the velocity field of the coupled airflow in the platform under different vehicle conditions is numerically simulated. It has been found that: when the train enters the station, the maximal piston wind velocity can reach 8 m/s with the air-conditioning supply air near the approach end significantly affected by the piston wind than at other positions. The study can provide a theoretical basis for the optimization of the airflow organization and energy consumption in the non-screen door subway station platform.
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VENCKUS, Žilvinas, Albertas VENSLOVAS i Mantas PRANSKEVIČIUS. "EXPERIMENTAL RESEARCH INTO AERODYNAMIC PARAMETERS OF A CYLINDRICAL ONE-LEVEL 8-CHANNEL CYCLONE". JOURNAL OF ENVIRONMENTAL ENGINEERING AND LANDSCAPE MANAGEMENT 22, nr 4 (17.12.2014): 284–91. http://dx.doi.org/10.3846/16486897.2014.973415.
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The Environmental Protection Laboratory of Vilnius Gediminas Technical University has developed and installed a one-level 8-channel cyclone with different internal structure, which is used for separation of particulate matter from air streams. Airflow velocity was measured in five points of each channel: at the end and the beginning of the channel, in the middle of the channel and in points arranged at 45° angle from the channel's end and beginning. The highest airflow velocity determined in 8-channel device by regulating volumes of peripheral and transit airflows with curvilinear semi-rings was in cyclone's channel 1, while the lowest – in channel 2. Contrary to the above, the highest airflow velocity in 8-channel cyclone by using quarter-rings without holes and with 5° opening angle of plates in holes was recorded in channel 2. Tests on aerodynamic resistance were carried out in airflow inlet and outlet ducts. In all cases analysed the highest aerodynamic resistance in 8-channel cyclone was determined when airflow distribution was regulated at 75/25 ratio with semi-rings. When quarter-rings without holes and with 5° opening angle of plates in holes were used, higher aerodynamic resistance in the system was created by using quarter-rings without holes, i.e. 0° opening of plates.
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Chen, Jinyan, Van-Thai Tran, Hejun Du, Junshan Wang i Chao Chen. "A Direct-Writing Approach for Fabrication of CNT/Paper-Based Piezoresistive Pressure Sensors for Airflow Sensing". Micromachines 12, nr 5 (30.04.2021): 504. http://dx.doi.org/10.3390/mi12050504.
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Airflow sensor is a crucial component for monitoring environmental airflow conditions in many engineering fields, especially in the field of aerospace engineering. However, conventional airflow sensors have been suffering from issues such as complexity and bulk in structures, high cost in fabrication and maintenance, and low stability and durability. In this work, we developed a facile direct-writing method for fabricating a low-cost piezoresistive element aiming at high-performance airflow sensing, in which a commercial pen was utilized to drop solutions of single-walled carbon nanotubes onto tissue paper to form a piezoresistive sensing element. The encapsulated piezoresistive element was tested for electromechanical properties under two loading modes: one loading mode is the so-called pressure mode in which the piezoresistive element is pressed by a normal pressure, and another mode is the so-called bending mode in which the piezoresistive element is bended as a cantilever beam. Unlike many other developed airflow sensors among which the sensing elements are normally employed as cantilever beams for facing winds, we designed a fin structure to be incorporated with the piezoresistive element for airflow sensing; the main function of the fin is to face winds instead of the piezoresistive element, and subsequently transfer and enlarge the airflow pressure to the piezoresistive element for the normal pressure loading mode. With this design, the piezoresistive element can also be protected by avoiding experiencing large strains and direct contact with external airflows so that the stability and durability of the sensor can be maintained. Moreover, we experimentally found that the performance parameters of the airflow sensor could be effectively tuned by varying the size of the fin structure. When the fin sizes of the airflow sensors were 20 mm, 30 mm, and 40 mm, the detection limits and sensitivities of the fabricated airflow sensors were measured as 8.2 m/s, 6.2 m/s, 3.2 m/s, 0.0121 (m/s)−2, 0.01657 (m/s)−2, and 0.02264 (m/s)−2, respectively. Therefore, the design of the fin structure could pave an easy way for adjusting the sensor performance without changing the sensor itself toward different application scenarios.
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Kelemenová, Tatiana. "AIRFLOW MEASUREMENT TEST DEVICE FOR AIRFLOW SENSORS". Acta Mechatronica 4, nr 4 (31.12.2019): 17–21. http://dx.doi.org/10.22306/am.v4i4.52.
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Basset, Patricia, Angélique Amelot, Jacqueline Vaissière i Bernard Roubeau. "Nasal airflow in French spontaneous speech". Journal of the International Phonetic Association 31, nr 1 (czerwiec 2001): 87–99. http://dx.doi.org/10.1017/s0025100301001074.
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The goal of this paper is to compare the degree of anticipatory and carryover phenomena in the behaviour of the velum during the production of French spontaneous speech, and to compare the data with the same speech material, but read. Airflows through the nose and the mouth were taken as an indirect indication of the velum behaviour. French is a language of special interest because there is a phonological contrast between oral and nasal vowels. The results show a tendency for nasal airflow to start before the nasal and a strong propensity to spread after the nasal. No differences could be established between speaking styles (spontaneous vs. read speech) regarding nasal airflow anticipation and carryover.
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Kravchenko, Ilia, Risto Kosonen i Simo Kilpeläinen. "Performance Analysis of the Demand-Based Ventilation in a Nordic Apartment Building". Applied Sciences 11, nr 1 (27.12.2020): 176. http://dx.doi.org/10.3390/app11010176.
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In general, new Finnish apartment buildings are equipped with mechanical balanced demand-based ventilation. The airflow rate in the kitchen hood is boosted on demand to improve pollutant extraction during cooking. However, in practice, it has been found that the system does not work as desired. The focus of the paper was to present the simulation results from a case building equipped with a ventilation system that is commonly used in Finland. In the analysis, the airflow rates are calculated for the room, apartment, and air handling unit (AHU) levels for various ventilation mode scenarios. A significant imbalance of over 10% between the supply and exhaust airflows at the room and apartment levels was observed in the boosting mode. This imbalance creates a pressure difference over the building envelope, particularly in small studio apartments. The calculated pressure difference for future buildings with high airtightness were at the warning level of 40 Pa below atmospheric level. The kitchen hood exhaust system showed a 28% lower airflow rate in certain scenarios. A new solution to guarantee the designed airflow rates was proposed and assessed. The new solution consists of replacing the apartment level flow control damper and a new balancing method for the kitchen hood exhaust branch. The proposed design was able to stay within 10% of the designed airflow rates in all operation modes.
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Soriano, Noelle Cielito, Kevin A. Janni, Baitong Chen, Melissa Wilson i Erin L. Cortus. "A Multi-Airspace Model to Investigate Airflow Patterns and Carbon Dioxide Emission Sources in Deep-pit Beef Cattle Finishing Facilities". Journal of the ASABE 67, nr 5 (2024): 1295–308. http://dx.doi.org/10.13031/ja.15956.
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HighlightsA multi-control volume mass balance approach tested with data from cattle finishing barns.Airflow estimates were highest in the barn airspace, compared to the animal-occupied zone and manure pit headspace.Slurry CO2 emission calculations were sensitive to gas concentration differences between zones and animal numbers.Abstract. An increasing number of cattle finishing barns in the Midwest are naturally ventilated (NV) with slatted floors over deep-pit manure storages. However, there is limited gas emission data currently available for this type of cattle housing and manure storage. Emission rate measurements are particularly challenging in NV barns where there are low gas concentrations and large variations in air velocity and direction. This research explores gas emission estimation using carbon dioxide (CO2) concentrations measured at the north and south wall openings, floor, nose level, and above the manure surface in the storage pit. With these measurements, three control volume mass balances for the barn airspace, animal-occupied zone (AOZ), and manure pit headspace were used to estimate airflows between control volumes and CO2 emissions rates. In this study, the estimated airflow and CO2 emission values for two NV barns were calculated for the summer, fall, and spring seasons. Nominal airflow rates calculated between the three control volumes for each barn were variable using three different solution approaches applied in this study. There was a general pattern where airflow through the barn airspace was larger than airflow between the barn airspace and animal-occupied zone, followed by airflow through the slatted floors. The range of estimated CO2 emissions considering both barns and three solution approaches was -1.16 g/s to 29.3 g/s. Overall, while calculated airflow and CO2 emission results were variable across three solution approaches, this study provides insight on a range of CO2 emissions and airflow rates through deep-pit NV cattle finishing facilities. Further model validation would be needed prior to the use of this model for gas mitigation purposes. Keywords: Airflow, Beef cattle, Carbon dioxide emission, Deep-pit barns, Modeling.
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Xing, Xiao, i Guo Ming Ye. "Numerical Simulation of Yarn Untwisting Mechanism in a Pneumatic Splicer Process". Applied Mechanics and Materials 229-231 (listopad 2012): 1721–24. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.1721.
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For better study of the airflow movement in the untwisting chamber of a pneumatic splicer, this paper uses a commercial computational fluid dynamics software FLUENT to realize the three dimensional numerical simulation for the characteristic of the airflows in the untwisting chamber. A three-dimensional grid and the realizable k- ε tur¬bulence model are used in this simulation. The characteristics of the air flows in different parts of the chamber are analysed according to the computed result. The airflow in the untwisting chamber can be divided into three regions in longitudinal section and two regions in cross section.
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Brownlie, Len, Collin Bailey, Jorge Carbo, Dan Judelson, Peter Ostafichuk, Jeff Allison i David Rival. "Measurement and Visualization of Airflow through Sports Textiles". Proceedings 49, nr 1 (15.06.2020): 21. http://dx.doi.org/10.3390/proceedings2020049021.
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In marathon running, maintenance of body temperature is critical for peak performance. Race apparel should maximize ventilation yet current fabric permeability standards are based on airflow rates that are not generated during running. A novel flow measurement device was used to measure airflow through textiles and the effects of fabric hole size, coverage area and standoff distance between a simulated torso and fabric at velocities of 3.3, 5.3 and 10 m.s−1. Fluorescent dye injection in a tow tank or flume permitted visualization of flow through fabrics. Ventilation is constrained by the low flow velocity in the stagnation area over the chest of an athlete, with freestream airflows of 3.3 and 10 m.s−1 reduced to 1.31 +/− 0.10 m/s (39.6%) and 3.51 +/− 0.27 m.s−1 (35.0%), respectively at a yaw angle of 20°. The initial low flow velocity precludes improvements in airflow despite changes in the standoff distance, fabric hole size or coverage area.
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Doyle, Lex William, Louis Irving, Anjali Haikerwal, Katherine Lee, Sarath Ranganathan i Jeanie Cheong. "Airway obstruction in young adults born extremely preterm or extremely low birth weight in the postsurfactant era". Thorax 74, nr 12 (26.09.2019): 1147–53. http://dx.doi.org/10.1136/thoraxjnl-2019-213757.
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BackgroundIt is unknown if adults born <28 weeks or <1000 g since surfactant has been available are reaching their full airway growth potential.ObjectiveTo compare expiratory airflow at 25 years and from 8 to 25 years of participants born <28 weeks or <1000 g with controls, and within the preterm group to compare those who had bronchopulmonary dysplasia with those who did not.MethodsAll survivors born <28 weeks or <1000 g in 1991–1992 in Victoria, Australia, were eligible. Controls were born contemporaneously, weighing >2499 g. At 8, 18 and 25 years, expiratory airflows were measured and the results converted to z-scores. Outcomes were compared between groups at age 25 years, and trajectories (change in z-scores per year) from childhood were contrasted between groups.ResultsExpiratory airflows were measured at 25 years on 164 of 297 (55%) preterm survivors and 130 of 260 (50%) controls. Preterm participants had substantially reduced airflow compared with controls at age 25 years (eg, zFEV1; mean difference −0.97, 95% CI −1.23 to –0.71; p<0.001). Preterm participants had lower airflow trajectories than controls between 8 and 18 years, but not between 18 and 25 years. Within the preterm group, those who had bronchopulmonary dysplasia had worse airflows and trajectories than those who did not.ConclusionsYoung adults born <28 weeks or <1000 g in the surfactant era, particularly those who had bronchopulmonary dysplasia, have substantially reduced airway function compared with controls. Some are destined to develop COPD in later adult life.
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Osabutey, Augustina, Brady Cromer, Alexander Davids, Logan Prouty, Noor Haleem, Robert Thaler, Richard Nicolai i Xufei Yang. "Distribution of Airflow and Media Moisture Content across Two Vertical Bed Biofilters". AgriEngineering 4, nr 1 (24.02.2022): 179–89. http://dx.doi.org/10.3390/agriengineering4010013.
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For its small square footage, a vertical bed biofilter was developed for odor emission mitigation for livestock facilities with limited area available for biofilter installation. However, a concern about the design is that airflow and moisture may be poorly distributed across the biofilter due to the effects of gravity. Relevant data are sporadic in the literature. To fill the knowledge gap, two vertical bed biofilters were constructed at a university swine facility and monitored for two months. The monitoring was taken at 27 grid points on each biofilter per field visit. Results revealed that both the airflow and medium moisture content were unevenly distributed. The sun-facing side of the biofilters had significantly lower medium moisture content (p < 0.01) due to solar-induced water evaporation. The side directly facing the barn exhaust had the highest airflow. Airflows varied along the height of the biofilters, but no significant difference was noted. The uniformity of airflow and moisture content, characterized by coefficient of variance (CV) and distribution uniformity (DU) respectively, were examined over the monitoring campaign. Possible reasons for uneven distribution were explored and recommendations are made to address the uniformity issue. The findings from the study are expected to further the development and implementation of biofiltration technology for livestock odor control.
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Wang, Junshi, Simon Mendez, Haibo Dong i Howard A. Stone. "Links between language, fluid dynamics, and the airflows that transport pathogens". Journal of the Acoustical Society of America 152, nr 4 (październik 2022): A287—A288. http://dx.doi.org/10.1121/10.0016300.
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Growing evidence shows that the airflows that accompany speech during social interactions contribute to the transport of pathogens, such as the SARS-CoV-2 virus. However, it is still elusive how the manners of articulation during speaking, such as time-varying airflow rate, and instantaneous teeth and lip movements, may affect the transport features of airflow exiting the mouth. We combine experimental and numerical approaches to investigate the flow patterns produced by representative vowels, such as /a/, /o/, and /i/, and consonants, such as /p/, /k/, /s/, and /h/, that have distinct articulatory characteristics. A 3D vocal tract is modeled with a temporally varying exit that captures key morphologic and kinematic features of the human vocal tract, including teeth and lips, during speaking. An incompressible flow solver based on a sharp-interface immersed-boundary-method (IBM) is employed to compute the resultant airflow. By comparing representative utterance pairs, like /apa/ and /aha/, we are able to isolate the effect of articulatory features and show significant differences in spatial-temporal patterns of airflow under the influences of a time-varying orifice, different orifice aspect ratios, and different relative lip-teeth positions. This work helps bring insight into the understanding of articulatory phonetics, and the links to different languages, from a fluid dynamics perspective.
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Han, Wenqi, Yaqing Peng, Xunmei Wu i Mengtao Han. "Spatiotemporal distribution prediction of coughing airflow at mouth based on machine learning—Part II: Boundary inference using neural network". E3S Web of Conferences 396 (2023): 01009. http://dx.doi.org/10.1051/e3sconf/202339601009.
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In the post-epidemic era, the trajectory of pathogenic airflows and droplets generated by coughing have been widely studied. However, owing to the limitations of measurement methods, there is a lack of detailed data on their spatiotemporal distribution at the mouth during coughing, which are the basis of research and the critical boundary conditions for computational simulation. Previous experiments have determined the velocity distribution of coughing airflow in spaces located far from the mouth. This study aims to collect detailed data at the mouth for use as the Computational Fluid Dynamics (CFD) boundary conditions from the experimental data. In Part I of this study, the critical parameters that describe the boundary conditions at the mouth for CFD simulation were obtained. Based on these parameters, this part infers the detailed temporal and spatial distribution velocity data of the coughing airflow at the mouth using a neural network. We performed CFD simulation on the prediction results with V=10.76 and M=4, and got FAC2=0.56 compared with the experimental values. The results obtained provided a generic detailed boundary condition for coughing airflow at the mouth and appropriate machine-learning parameters. This study can provide more accurate boundary conditions for simulating the propagation of pathogenic airflow and a supplementary database for epidemic prevention research.
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Lampret, Žiga, Gorazd Krese i Matjaž Prek. "Enhancing cooling performance via airflow temperature fluctuations". E3S Web of Conferences 111 (2019): 02072. http://dx.doi.org/10.1051/e3sconf/201911102072.
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In ventilated and air-conditioned indoor environment, air movement substantially impacts thermal sensation and comfort of occupants from the point of view of whole body and local thermal sensation. Skin temperature and its rate of change are important factors for thermal sensation. Both are affected by the airflow velocity and temperature changes around the body which causes skin temperature fluctuations and changes in convective heat transfer. In this study the impact of temperature fluctuations in airflow on human thermal sensation was examined. For the purposes of the study, an air handling unit was designed for generating airflows with temperature fluctuations and used in a subjective experiment. The experimental study indicates that temperature fluctuations possibly influence the human perception of air movement with a distinct cooling effect.
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Pan, Jin, i Feng Jin. "Design and performance analysis of a discontinuous spiral baffle heat exchanger". Journal of Physics: Conference Series 2709, nr 1 (1.02.2024): 012006. http://dx.doi.org/10.1088/1742-6596/2709/1/012006.
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Abstract In this paper, a new type of heat exchanger with discontinuous spiral baffles is designed, and its performance on heat transfer is analyzed by numerical simulation. The research results show that the airflow in shell-side flows by a similar helical way, “Flow dead zone” is not found. The high enthalpy airflow’s temperature decreases about 38% of the inlet air temperature by cooling down with a convective heat transfer coefficient of 344.4 W/(m2·K), while the decrease of the airflow pressure is 30%.
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Przydrozny, Edward, i Aleksandra Przydrozna. "Temperature and airflow setting in dual-duct ventilation systems". E3S Web of Conferences 116 (2019): 00063. http://dx.doi.org/10.1051/e3sconf/201911600063.
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Past experiences of excess energy consumption and malfunctioning controls introduced prejudice when considering dual-duct ventilation systems during design stages. Modern technologies, however, can be used to improve performance and control of dual-duct systems, thus making these a sensible and safe design option. In the paper, we discuss challenges associated with setting the warm and cold supply air temperatures and how these set-points affect the airflows. We present limitations in temperature settings, due to instantaneous room thermal conditions and the individual design temperature requirements. Portions of warm and cold air (the ratio of these in the ventilating airflow) affect the transport costs of ventilating airflow. In many cases, rational control of warm and cold air temperature set-points, in a yearly cycle, enables distribution of similar portions of warm and cold air within the system. Even airflows in warm and cold air installations minimise the overall flow resistance, so that the air transport costs are minimal. Simultaneously, apart from minimising the energy for air transport, the primary energy demand for air treatment should be controlled and minimised.
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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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Yamamoto, Toshiaki, Andrew Viner, Robert Donovan i David Ensor. "Model Study of Contaminant Flow in the Vicinity of Semiconductor Processing Equipment". Journal of the IEST 33, nr 4 (1.07.1990): 25–31. http://dx.doi.org/10.17764/jiet.2.33.4.g31703341581611q.
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A continuous particle monitoring system was set up to. identify short-term particle bursts that reflect equipment operation and personnel activity within the photolithography bay of a cleanroom. The frequency and magnitude of the bursts vary with location and strongly depend on airflow, especially departures from vertical laminar flow introduced by equipment placement and/or human traffic. For example, the particle concentration above a stepper electronics cabinet was significantly reduced by moving the cabinet away from the cleanroom wall. Also, the particle concentration above the photoresist coater is very high during the operation of the wafer spinner; therefore, particles generated should be swept away by the airflows in order to minimize the particle transport to the wafer processing area. Numerical simulation of the airflow around two selected pieces of processing equipment was performed to better explain particle transport from these sources. Zones of recirculation and particle trapping, as predicted by this modeling, were shown to exist near the equipment. The improvement in airflow distributions results in more complete and rapid removal of particles from the vicinity of the equipment.
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Deng, Tian, Wei Chen, Xing-ming Ren, Shuai Jiang i Chao-hua Yuan. "Experiment on the Breakup of Liquid Jets in Different Cross-Airflows". International Journal of Aerospace Engineering 2019 (1.07.2019): 1–13. http://dx.doi.org/10.1155/2019/2576568.
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The experiment is conducted with a high-speed camera to investigate the breakup processes of liquid jets in uniform, shear-laden, and swirling cross-airflows. The liquid used in the test is water, the nozzle diameter is 2 mm, and the liquid-to-air momentum flux ratio q ranges from 5 to 3408.5. The results indicate that liquid jets break up to form small droplets in the uniform cross-airflow. There is an exponential relation between the broken position and q. In the shear-laden cross-airflow, the penetration depth of the jet is similar to that of the uniform case, both of which increase with the increase of q. When q and the mean Weber number are the same as the uniform case, the penetration depth of the jet increases by 25% when the velocity ratio of the upper and lower inlets is UR=5; the jet penetration depth decreases by 47.2% when the ratio of UR=0.2 and the jet breaks up quickly and the atomization effect will be better. In the swirling cross-airflow, the jet trajectory is similar to the uniform case and also satisfies the exponential property. When the swirl is weak (swirling number SN=0.49), the jet penetration depth increases compared to the uniform case; when the swirl is strong (SN=0.82), the cross-swirling airflow restrains the jet penetration depth.
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Alsved, M., A. Civilis, P. Ekolind, A. Tammelin, A. Erichsen Andersson, J. Jakobsson, T. Svensson i in. "Temperature-controlled airflow ventilation in operating rooms compared with laminar airflow and turbulent mixed airflow". Journal of Hospital Infection 98, nr 2 (luty 2018): 181–90. http://dx.doi.org/10.1016/j.jhin.2017.10.013.
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Mahmud, Md Sultan, Azlan Zahid, Long He, Heping Zhu, Daeun Choi, Grzegorz Krawczyk i Paul Heinemann. "Development of an Automatic Airflow Control System for Precision Sprayers Based on Tree Canopy Density". Journal of the ASABE 65, nr 6 (2022): 1225–40. http://dx.doi.org/10.13031/ja.14972.
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HighlightsA LiDAR-guided automatic airflow control system for precision sprayers was developed.Three models were built to measure the amount of airflow required for apple trees.The study confirmed that adjusting the fan inlet could control airflow penetration into tree canopies.Results suggest that the system can reduce spray drift and off-target losses. Abstract. The airflow discharged from orchard airblast sprayers is a primary component for successfully carrying spray droplets to the target trees. Because of the variation in orchard tree canopies, control of the airflow to minimize off-target loss during spray application is essential. An automatic airflow control system for precision sprayers was developed to maximize spray droplet coverage on targets and minimize off-target loss while considering the tree canopy densities. The primary component of the system was an iris damper, which was designed as a retrofit attachment on the fan inlet of a three-point airblast intelligent sprayer. A 3D light detection and ranging (LiDAR) sensor was installed at the top of the sprayer to acquire the tree canopy data. A motor was employed to control the damper opening with a micro-controller. To develop the models required for automatic airflow control, field experiments were conducted at three canopy density orchards with different cultivars (GoldRush, Gala, and Fuji). A total of 15 trees (five trees from each cultivar) were randomly selected, and five different damper openings (openings 1, 2, 3, 4, and 5) were tested for each tree. Opening 1 represented the same air inlet as a traditional precision airblast sprayer, while openings 2, 3, 4, and 5 were the sequentially reduced air inlets of the sprayer. A canopy density measurement algorithm was scripted to measure the canopy point density of individual trees. Three models were built to show relationships between (1) tree canopy point densities and airflows; (2) canopy densities and damper openings; and (3) damper opening and motor steps. The combination of the two models (2 & 3) was used to assess the amount of airflow required for a specific canopy density. Field validations for medium and high-density trees showed that the system achieved adequate spray penetration at the top, middle, bottom, back-left, and back-right positions of the tree sections and reduced off-target loss at the ground and edge of next row sections using openings 4 and 2, respectively. However, the mechanical motion of the damper required 3 s to move from minimum to maximum opening, so the average canopy density was recommended to control the airflow. The overall results suggested that the automatic airflow control system could reduce spray drift and off-target losses and improve spray application efficiency in orchards. Keywords: Automation, Canopy sensing, Fan inlet, Precision spraying, Variable rate application.
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Lee, Linda D., Matthew Berkheiser, Ying Jiang, Brenda Hackett, Ray Y. Hachem, Roy F. Chemaly i Issam I. Raad. "Risk of Bioaerosol Contamination With Aspergillus Species Before and After Cleaning in Rooms Filtered With High-Efficiency Particulate Air Filters That House Patients With Hematologic Malignancy". Infection Control & Hospital Epidemiology 28, nr 9 (wrzesień 2007): 1066–70. http://dx.doi.org/10.1086/519866.
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Objective.To examine the impact of cleaning and directional airflow on environmental contamination with Aspergillus species in hospital rooms filtered with high-efficiency particulate air (HEPA) filters that house patients with hematologic malignancy.Design.Detailed environmental assessment.Setting.A 475-bed tertiary cancer center in the southern United States.Methods.From April to October 2004, 1,258 surface samples and 627 bioaerosol samples were obtained from 74 HEPA-filtered rooms (in addition, 88 outdoor bioaerosol samples were obtained). Samples were collected from rooms cleaned within 1 hour after patient discharge and from rooms before cleaning. Positive and negative airflows were evaluated using air-current tubes at entrances to patient rooms.Results.Of 1,258 surface samples, 3.3% were positive for Aspergillus species. Univariate analysis showed no relationship between cleaning status and occurrence of Aspergillus species. Of 627 bioaerosol samples, 7.3% were positive for Aspergillus species. Multiple logistic analysis revealed independently significant associations with detection of Aspergillus species. Cleaned rooms positive for Aspergillus species had a higher geometric mean density of colonies than that of rooms sampled before cleaning (18.9 vs 5.5 colony-forming units [cfu] per cubic meter; P = .0047). Rooms with positive airflow had a detection rate for bioaerosol samples equivalent to that of rooms with negative airflow (7.3% vs 7.8%; P = .8). There was no significant difference in the density of Aspergillus species between rooms with negative airflow and rooms with positive airflow (12.5 vs 8.4 cfu/m3; P = .33).Conclusions.Concentration of bioaerosol contamination with Aspergillus species was increased in rooms sampled 1 hour after cleaning compared with rooms sampled before cleaning, suggesting a possible correlation between reentrained bioaerosols (ie, those suspended by activity in the room) after cleaning and the risk of nosocomial invasive aspergillosis.
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Leopold, Donald A. "Perception of Airflow Is More Important Than Actual Airflow". Archives of Otolaryngology–Head & Neck Surgery 132, nr 6 (1.06.2006): 597. http://dx.doi.org/10.1001/archotol.132.6.597.
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Zeng, Jie, Zhi Yan Hou i Hao Zeng Jiang. "The Numerical Simulation of Swirling Airflow Field for Different Swirling Airflow Head in Swirling Airflow Finishing". Applied Mechanics and Materials 678 (październik 2014): 582–86. http://dx.doi.org/10.4028/www.scientific.net/amm.678.582.
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The key of swirling airflow finishing is how to generate the swirling airflow. In the paper, three swirling airflow head are discussed according the manners of tangential inflow. By means of FLUENT, the general software of CFD, the swirling airflow field from different airflow head is simulated. The simulation results are shown by the flow line graphs, tangential velocity, radial distribution graphs, etc. All we have studied is as the basis for the determination of the application scope of each swirling airflow head.
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Latif, Haider, Samira Rahnama, Alessandro Maccarini, Goran Hultmark, Peter V. Nielsen i Alireza Afshari. "Precision Ventilation in an Open-Plan Office: A New Application of Active Chilled Beam (ACB) with a JetCone Feature". Sustainability 14, nr 7 (2.04.2022): 4242. http://dx.doi.org/10.3390/su14074242.
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Mixing ventilation systems effectively improves thermal comfort in open-spaces due to adequate turbulent mixing of the cold stream with ambient air. This study introduces the concept of precision ventilation for achieving local thermal comfort in a mixing ventilation system. This precision ventilation system provides asymmetrical airflows from an active chilled beam (ACB) to each of the office occupants. These ACBs provide air velocities with different magnitudes and directions. To achieve different magnitudes and directions, JetCones are used to vary the airflow in different parts of the ACB. The performance of the precision ventilation system was analyzed using full-scale laboratory experiments and computational fluid dynamic (CFD) simulations. The full-scale laboratory experiments were conducted in a 4.2 m × 3 m × 2.8 m (L × W × H) thermal isolated room with an open-plan dual desk-chair setup. The jet-cones in the ACB unit were adjusted to throw the required amount of flow to the occupants. The occupants had different metabolic rates of 1.2, 1.4, and 1.6 in a warm office space. The room set point temperatures varied between 23 and 26 °C. The experimental and CFD results show that occupants facing symmetrical airflow distribution and with a constant 1.2 metabolic rate had a similar PMV index. The occupants with 1.2, 1.4, and 1.6 metabolic rate were exposed to asymmetrical airflows, i.e., 30%, 58%, and 70% of the total airflow. Occupants with higher metabolic rates were kept thermally neutral, in the −0.5 to +0.5 PMV range, by increasing the air velocity and room temperature to 0.4 m/s and 25 °C, respectively.
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Li, Jiaying, Wei You i Wowo Ding. "The potential of the height-to-width ratio as an indicator to characterize the ventilation performance of a canyon in the urban context". Journal of Physics: Conference Series 2600, nr 10 (1.11.2023): 102021. http://dx.doi.org/10.1088/1742-6596/2600/10/102021.
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Abstract The height-to-width ratio (H/W) of canyons has been proven to be a significant indicator related to ventilation performance (airflow status and ventilation efficiency), which can help designers assess urban ventilation performance and guide the design quickly. However, previous research focused on the canyons in ideal geometric settings rather than in the urban context. This study explores whether the relationships between H/W, airflow status, and ventilation efficiency of ideal form studies apply to canyons in the urban context. Firstly, the relationship between the three in ideal geometric settings is sorted out by literature reviews. Then, the validity of the findings of ideal form studies in in the urban context is verified, using a typical residential area, Nanjing, China, as a case. This study found that H/W can affect the ventilation performance to a certain extent in in the urban context. However, most canyons’ airflows are affected by complex environmental factors, turning into different flow types (Deviation Type, Crossing Type, and Multivortex Type), which reduces the correlation between H/W, airflow status, and ventilation efficiency of canyons in the urban context.
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Hou, Min, Jiheng Ni i Hanping Mao. "Effects of Airflow Disturbance on the Content of Biochemical Components and Mechanical Properties of Cucumber Seedling Stems". Agriculture 13, nr 6 (26.05.2023): 1125. http://dx.doi.org/10.3390/agriculture13061125.
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In order to explore the changes in biochemical components and mechanical properties of cucumber seedlings with dwarfing characteristics under airflow disturbance treatment, ‘Jinyou No. 1’ cucumber seedlings were used as experimental materials and the split-plot design was used. The cucumber seedlings were treated with airflow disturbance with two airflow temperatures of 25 ± 5 °C and 35 ± 5 °C as the main factors and four airflow velocities of 1, 3, 6 and 9 m/s as the secondary factors. At the same time, cucumber seedlings without airflow disturbance were used as controls to study the effects of airflow temperature and velocity on the biochemical components and mechanical properties of cucumber seedling stems. The results showed that with the increase in airflow velocity, the content of the stems’ biochemical components increased to varying degrees, and the bending load, shear load, elastic modulus, bending strength and shear strength of the seedling stems also increased. Under the same airflow velocity, the biochemical component content and the accepted load of seedlings under the 25 ± 5 °C airflow temperature treatment were larger than those under the 35 ± 5 °C airflow greenhouse treatment, but the elastic modulus, bending strength and shear strength of seedlings under the 25 ± 5 °C airflow temperature treatment were lesser than those under the 35 ± 5 °C airflow temperature treatment. Using the grey relational analysis method, the correlation degree between the biochemical components of the stem and the mechanical properties of the stem was different. The correlation degree between the biochemical components of the seedling stem and the mechanical properties under different airflow temperature treatments was significant. The correlation degree between the biochemical components of the seedling stem and the mechanical properties under different airflow velocity treatments was greater than 0.60, indicating that the biochemical components of the seedling stem under airflow velocity treatments had a greater influence on the mechanical properties. In summary, airflow disturbance significantly affected the biochemical components and mechanical properties of cucumber seedlings. The biochemical components and mechanical properties of seedlings were negatively correlated with airflow temperature and positively correlated with airflow velocity. With a decrease in airflow temperature and an increase in airflow velocity, the biochemical components and mechanical properties of seedlings increased.
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Shang, Shanshan, Chongwen Yu i Meiling Li. "Numerical simulation of swirling airflow dynamics in vortex spinning". Textile Research Journal 88, nr 7 (30.01.2017): 833–43. http://dx.doi.org/10.1177/0040517517690631.
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In this paper, a computational fluid dynamics model has been established and a three-dimensional numerical simulation of the flow characteristics of airflow in a vortex spinning nozzle has been carried out. A realizable k-ɛ model is used to simulate the turbulence of airflow in the nozzle. Unstructured tetrahedral grids which have good adaptability to complex boundaries are used in this paper to mesh the computational region. The computational model of the airflow field is solved and the characteristics of airflow in a vortex spinning nozzle are obtained. The results show that the flow principle of the airflow is determined by the pressure distribution of the airflow. The airflow field in the nozzle can be divided into external and internal areas, according to the flow characteristics and functions of airflow. The trajectory of swirling airflow from the jet orifices has a regular rotational motion within the twisting chamber, but the trajectory of swirling airflow from nozzle inlet is complex and backflow occurs; finally, these two strands of airflow are fused together as a regular rotational motion.
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Eschenbacher, William L. "Defining Airflow Obstruction". Chronic Obstructive Pulmonary Diseases: Journal of the COPD Foundation 3, nr 2 (2016): 515–18. http://dx.doi.org/10.15326/jcopdf.3.2.2015.0166.
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Clarke, R. W., i A. S. Jones. "Nasal airflow sensation". Clinical Otolaryngology 20, nr 2 (kwiecień 1995): 97–99. http://dx.doi.org/10.1111/j.1365-2273.1995.tb00022.x.
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Freed, Arthur N., i Carol A. Hirshman. "Airflow-induced Bronchoconstriction". Anesthesiology 69, nr 6 (1.12.1988): 923–32. http://dx.doi.org/10.1097/00000542-198812000-00019.
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Quanjer, Philip H., Brendan Cooper, Gregg L. Ruppel, Maureen P. Swanney, Janet Stocks, Bruce H. Culver i Bruce R. Thompson. "Defining airflow obstruction". European Respiratory Journal 45, nr 2 (31.01.2015): 561–62. http://dx.doi.org/10.1183/09031936.00126014.
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Miller, Martin R. "Defining airflow obstruction". European Respiratory Journal 45, nr 2 (31.01.2015): 560. http://dx.doi.org/10.1183/09031936.00157114.
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Smith, Margaret, i Om Kurmi. "Defining airflow obstruction". European Respiratory Journal 45, nr 2 (31.01.2015): 563–64. http://dx.doi.org/10.1183/09031936.00207014.
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Turpin, Ivan M. "Laminar Airflow Systems". AORN Journal 68, nr 3 (wrzesień 1998): 366. http://dx.doi.org/10.1016/s0001-2092(06)62403-4.
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Friberg, Barbro. "Laminar Airflow Systems". AORN Journal 68, nr 3 (wrzesień 1998): 366–68. http://dx.doi.org/10.1016/s0001-2092(06)62404-6.
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McQuarrie, Donald G., John L. Glover i Mary M. Olson. "Laminar Airflow Systems". AORN Journal 51, nr 4 (kwiecień 1990): 1035–48. http://dx.doi.org/10.1016/s0001-2092(07)66844-6.
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Johansen, O. "Integrated airflow meter". Medical & Biological Engineering & Computing 27, nr 2 (marzec 1989): 210–12. http://dx.doi.org/10.1007/bf02446233.
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