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1
Song, Xin-Yi, Qing-Chang Lu, and Zhong-Ren Peng. "Spatial Distribution of Fine Particulate Matter in Underground Passageways." International Journal of Environmental Research and Public Health 15, no. 8 (July 25, 2018): 1574. http://dx.doi.org/10.3390/ijerph15081574.
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The unfavorable locations of underground infrastructures and poor ventilation facilities can result in the deterioration of enclosed air quality. Some researchers have studied air quality and ventilation measures in different types of underground buildings. However, few studies have investigated the pollution in pedestrian passageways connecting underground structures. Hence, in this paper, we attempted to investigate the spatial distribution of fine particulate matter (PM2.5) in underground passageways. First, measurements were designed and conducted in a pedestrian passageway beneath the Shanghai South Railway Station, Shanghai, China. Second, numerical simulations were performed based on computational fluid dynamic (CFD) technology. Finally, the numerical simulations were extended to examine impacts of the ventilation measures on PM2.5 concentration with different inlet positions and air velocity in underground passageways. The simulation results showed good agreement with the experimental data, and the numerical model was validated to be an effective method to investigate the spatial distribution of PM2.5 in underground passageways. Results suggest that building additional entrances is an advisable method for improving air quality in the underground passageways of the Shanghai South Railway Station, while jet fans are not recommended. Findings of this study offer suggestions for mitigating PM2.5 pollution in underground passageways.
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Adamčík, Martin, Tomáš Svěrák, and Peter Peciar. "PARAMETERS EFFECTING FORCED VORTEX FORMATION IN BLADE PASSAGEWAY OF DYNAMIC AIR CLASSIFIER." Acta Polytechnica 57, no. 5 (October 31, 2017): 304. http://dx.doi.org/10.14311/ap.2017.57.0304.
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<p>Air classification of particulate materials is a method of classifying particles into coarse and fine fractions based on their size, density, or shape. Performance of the rotor air classifier is affected by operating parameters which include the classifier rotor speed, air inlet velocity and material feed rate. Effects of operating and structural parameters on turbulent flow field patterns inside of a dynamic air classifier are investigated. Increasing the computing power, together with new turbulence models and<br />approaches, to simulate complex fully turbulent problems by solving Navier-Stokes equations allows studying and capturing smaller flow structures and properties more accurately. Velocity vector maps for varying operating parameters are studied by means of numerical simulations. The experimental section includes a visualization of flow patterns and velocity vector maps in the rotor region by the use of the particle image velocimetry (PIV). Results are compared and discussed.</p>
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Gao, Ran, Angui Li, Wenjun Lei, Yujiao Zhao, Ying Zhang, and Baoshun Deng. "Study of a proposed tunnel evacuation passageway formed by opposite-double air curtain ventilation." Safety Science 50, no. 7 (August 2012): 1549–57. http://dx.doi.org/10.1016/j.ssci.2012.03.007.
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Li, Da. "Design for New Type Centrifugal Fan and Passageway of the Air Conditioner Indoor Unit." IOP Conference Series: Earth and Environmental Science 632 (January 14, 2021): 052003. http://dx.doi.org/10.1088/1755-1315/632/5/052003.
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Yue, Yu, Wen Jiang, Zhang Zhang, Chen Wang, Zong You Shao, Zhi Min Tang, Wei Dong Shen, Ke Li, and Guang Hui Liu. "Investigations of the Energy-Saving Technology of a Cloud Computing Data Center." Applied Mechanics and Materials 556-562 (May 2014): 6228–31. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.6228.
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This paper shows the energy consumption distribution of current data center, presents some effective energy-saving measures to reduce the energy consumption of a cloud computing data center. Raise an effective way to optimize the air distribution of the data center such as sealing the cold passageway. Through the use of ADU can solve the local overheating inside the equipment cabinet. The use of the modularization UPS, the high-voltage direct current technology and harmonic suppression can improve the efficiency of the power supply system.
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Wang, A. Cheng, Kuan Yu Chen, Ken Chuan Cheng, and H. H. Chiu. "Elucidating the Effects of Helical Passageways in Abrasive Flow Machining." Advanced Materials Research 264-265 (June 2011): 1862–67. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.1862.
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Conventional AFM have difficulty achieving uniform roughness of an axial distribution in circular hole polishing due to limited unitary axial motion of abrasive media. Therefore, this work develops mechanism designs for different passageways to obtain multiple flowing paths of an abrasive medium, whose flowing behavior enhances polishing effectiveness by increasing the abrasive surface area and radial shear forces. The motion of the abrasive medium is studied by utilizing the design of the mold cores, which mold shapes include the circular passageway and helical passageway. The optimum design of the different passageways is then verified using CFD-ACE+ numerical software. Analytical results indicate that the optimum design is the mechanism with a passageway of six helices. Furthermore, surface roughness measurements demonstrate the increase in uniformity and the roughness improvement rate (RIR). Experimental results for surface roughness indicate that roughness deviation of six helices passageway of approximately 0.1001 m Ra is significantly better than those on a circular passageway of around 0.1760 m Ra. Additionally, the six helices passageway is also superior to circular passageway in reducing roughness improvement rate (RIR) by roughly 85% compared with RIR 75% for the circular passageway.
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Hirabayashi, H., and H. Shimada. "Panel Discussion 2: ^|^ldquo;Management of Air and Food Passageway Foreign Bodies^|^rdquo;^|^mdash;Introduction." Nihon Kikan Shokudoka Gakkai Kaiho 65, no. 2 (2014): 148. http://dx.doi.org/10.2468/jbes.65.148.
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Gao, Ran, Angui Li, Wenjun Lei, Yujiao Zhao, Ying Zhang, and Baoshun Deng. "A novel evacuation passageway formed by a breathing air supply zone combined with upward ventilation." Physica A: Statistical Mechanics and its Applications 392, no. 20 (October 2013): 4793–803. http://dx.doi.org/10.1016/j.physa.2013.06.030.
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Janczarek, Iwona, Izabela Wilk, Anna Wiśniewska, Roland Kusy, Katarzyna Cikacz, Martyna Frątczak, and Przemysław Wójcik. "Effect of air temperature and humidity in a stable on basic physiological parameters in horses." Roczniki Naukowe Polskiego Towarzystwa Zootechnicznego 16, no. 3 (September 30, 2020): 55–65. http://dx.doi.org/10.5604/01.3001.0014.4154.
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The aim of the study was to analyse selected air parameters in a stable (microclimate) and the basic physiological parameters of horses housed in the stable in different seasons of the year. The research material was 12 adult hot-blooded horses kept in a brick stable with stalls. Air parameters in the stable (temperature in the passageway, temperature in the stall at two points, relative humidity in the passageway, and relative humidity in the stall at two points) were determined four times in one year, in summer, autumn, winter and spring. Measurements were made with a Bluetooth BLE-LOGGER LB-518 battery-operated cordless thermo-hygrometer at 12 noon at five points in the stable located 300 cm apart. Physiological parameters of the horses, i.e. internal body temperature (Veterinär SC 12 veterinary thermometer), heart rate (Polar ELECTRO OY RS800CX with PolarProTrainer 5.0. software), and respiratory rate (with a manual stopwatch) were measured at 6 a.m. and 6 p.m. on each day of the study. The season of the year was found to have a significant influence on the microclimate of the stable. To ensure optimal air humidity, airing of the stable should be limited only in winter and periodically in autumn. It is also worth emphasizing that the stable microclimate has a marked effect on the basic physiological parameters of horses. High temperature and relative humidity in the stable can cause unfavourable changes in the form of an increase in evening body temperature in the summer and a decrease in the winter. The remaining parameters, i.e. heart rate and respiratory rate, can also unfavourably increase, mainly in the summer. Horses should have fewer problems maintaining normal physiological parameters in winter, even fewer in autumn, and the fewest in spring.
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Cheng, Ken Chuan, Kuan Yu Chen, A. Cheng Wang, and Yan Cherng Lin. "Study the Rheological Properties of Abrasive Gel with Various Passageways in Abrasive Flow Machining." Advanced Materials Research 126-128 (August 2010): 447–56. http://dx.doi.org/10.4028/www.scientific.net/amr.126-128.447.
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Abrasive flow machining (AFM) is a simple and efficient method to remove recasting layers making by wire electrical discharge machining (WEDM). However, conventional AFM methods have difficulty achieving uniform roughness of an axial distribution in circular hole polishing due to limited unitary axial motion of abrasive media. Therefore, this work develops mechanism designs for different passageways to obtain multiple flowing paths of abrasive medium, whose flowing behavior enhances polishing effectiveness by increasing the abrasive surface area and radial shear forces. The motion of the abrasive medium is studied by utilizing different mold cores, which mold shapes include the circular, hollow and helical passageway. The optimum design of the passageways is then verified using CFD-ACE+ software, numerical results indicate that passageway with six helices performed better in the uniform surface roughness than others’ do. Experimental results show that roughness deviation of six helices passageway of approximately 0.100 m Ra is significantly better than those on a circular passageway of around 0.1760 m Ra. Additionally, the six helices passageway is also superior to circular passageway in reducing roughness improvement rate (RIR) by roughly 87% compared with RIR 67.7% for the circular passageway.
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Elad, David, Sara Naftali, Moshe Rosenfeld, and Michael Wolf. "Physical stresses at the air-wall interface of the human nasal cavity during breathing." Journal of Applied Physiology 100, no. 3 (March 2006): 1003–10. http://dx.doi.org/10.1152/japplphysiol.01049.2005.
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The nose is the front line defender of the respiratory system and is rich with mechanoreceptors, thermoreceptors, and nerve endings. A time-dependent computational model of transport through nasal models of a healthy human has been used to analyze the fields of physical stresses that may develop at the air-wall interface of the nasal mucosa. Simulations during quiet breathing revealed wall shear stresses as high as 0.3 Pa in the noselike model and 1.5 Pa in the anatomical model. These values are of the same order of those known to exist in uniform large arteries. The distribution of temperature near the nasal wall at peak inspiration is similar to that of wall shear stresses. The lowest temperatures occur in the vicinity of high stresses due to the narrow passageway in these locations. Time and spatial gradients of these stresses may have functional effects on nasal sensation of airflow and may play a role in the well-being of nasal breathing.
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Guryev, Alim, Nartmir Khanov, Olga Mareeva, Vasilii Fartukov, Anna Zhuravleva, and Aleksandra Verkhoglyadova. "New way to dampen the energy of medium- and high-pressure flows." E3S Web of Conferences 264 (2021): 03046. http://dx.doi.org/10.1051/e3sconf/202126403046.
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The current practice of hydraulic engineering construction applies four methods for damping extra energy of excess water discharge: throwing out the stream into the tailwater; using twisting of the stream in the water passageway, in a water-well, and on a multistage drop; and energy damping in a vertical shaft. The cheapest method is energy damping by throwing the jet into the downstream reservoir. The main disadvantages limiting the use of this method include the need for appropriate topographic conditions in the tailrace basin, strong rocks in the river channel, and the possibility of water throwing at a large distance from the hydropower project, which restricts the use of this method. Extra energy damping with the use of twisting flow in the water passageway requires complex structures, providing for a rotational movement of water and forming a deep vacuum in the outlet conduit. The breaking of vacuum requires a large amount of air, which causes dynamic modes, and its removal complicates the design of energy damping structures. The most reliable way of energy damping is damping in a stilling well. But the disadvantages of water-sucking wells are low efficiency accompanied by an uneven distribution of specific discharges in the inlet section and a sharp increase in the cost at high-pressure hydroelectric installations. The use of multistage cross-fall drastically facilitates the operation of a stilling well and serves as its supplement. Energy damping in a vertical shaft is easy to use. Still, it results in trapping a large amount of air at all operating modes, which has limited its practical use in hydraulic engineering construction. However, the damping of flow energy in a vertical shaft except for possible air supply has shown high efficiency of operation in combination with a diversion water pipe with a reverse slope. A variant of such design of flow energy damping in a vacuum vertical shaft has been developed and studied as applied to conditions of the Rogun hydropower project. Model studies of the design on the scale of 1:100 showed high efficiency and reliability in all possible ranges of discharged flow rates.
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Mkilaha, I. S. N., M. Inoue, D. Kawai, I. Naruse, and K. Ohtake. "Simultaneous reduction of particulate matter and NOx in a diesel engine by compressed gas injection: macroscopic study at residual load." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 211, no. 3 (March 1, 1997): 227–36. http://dx.doi.org/10.1243/0954407971526380.
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A modified pre-chamber of an indirect injection (IDI) diesel engine was used to elucidate the influence on emissions of compressed air injection into the pre-chamber during combustion. The test parameters were air injection timing and arrangements of gas injection. This paper presents the experimental results for two types of injection arrangements; I- and Y-type. The I-type is arranged such that the gas injection jet and fuel injection nozzle are in opposite directions, while the Y-type is such that it forms a ‘Y’ shape with the nozzle and the passageway. Results obtained reveal that the Y-type arrangement is superior in combustion characteristics and emissions reduction to the I-type. A remarkable reduction in both particulate matter (PM) and NO x is realized at air injection timings during 35° and 65° after top dead centre (ATDC). The reduction mechanism can be explained as due to the induced turbulence which improves mixing and heat transfer. The effect of the modifications on the performance of the engine was evaluated based on the fuel economy and efficiency. This evaluation has shown that the test cylinder approximates closely to the normal cylinder of the original engine.
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Shirvani, K., and Amir Firouzi. "Aluminide Coating Formation on Internal Passages of GTD-111 Superalloy by Slurry Technique." Materials Science Forum 595-598 (September 2008): 185–90. http://dx.doi.org/10.4028/www.scientific.net/msf.595-598.185.
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The diffusion aluminide coatings are widely used in the air-cooling passages to protect their surfaces against high temperature corrosion. In this study plain and Si-modified aluminide coatings were applied by slurry technique on internal surfaces of Ni-base GTD-111 superalloy cylindrical specimens derived from a gas turbine air-cooled blade. The slurries containing Al or Al plus Si powders were applied on internal surfaces by injection method. Then, the samples were heated to high temperature (800-1000°C) to form the coatings. Optical, SEM-EDS, and XRD were utilized for characterizing microstructures and phase compositions of the coatings. The thicknesses of applied coatings on internal surfaces were in the range of 30-50 μm that meets specifications for diffusion coatings in such application (i.e. 25-756m). The examinations demonstrated that both coating types were contained β-NiAl phase as the matrix. The uniformities of coatings applied on different surface positions of passageway were determined. In addition, the effects of time and temperature of coating process as well as mass of dried slurry on the coating thickness were also discussed.
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Mullisen, R. S. "Thermal Engineering Design Project: Disk Brake Cooling Simulation." International Journal of Mechanical Engineering Education 25, no. 4 (October 1997): 299–305. http://dx.doi.org/10.1177/030641909702500406.
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A thermal engineering design project involving simulated cooling of vented and nonvented disk brakes is described. A heated copper tube was rotated in a manner that replicated the motion of a single vented passageway inside a disk brake rotor. The class assignment required design and construction of equipment, and data reduction using the lumped heat capacity method to obtain heat transfer correlations. The seven student groups plus the author produced 238 data points which were collectively correlated into two Nusselt number curves. The curve for the nonvented brakes simulation was benchmarked against the published literature for a cylinder in crossflow; the deviation was about 31%. The results from the vented brakes simulation which, in addition to the external air flow, had an internal radial flow driven by the rotation produced a 30% cooling augmentation over the nonvented simulation.
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Xue, Zhigang, Jiming Hao, Fahe Chai, Ning Duan, Yizhen Chen, Jindan Li, Fu Chen, Simei Liu, and Wenqing Pu. "Air Quality Impact of the Coal-Fired Power Plants in the Northern Passageway of the China West-East Power Transmission Project." Journal of the Air & Waste Management Association 55, no. 12 (December 2005): 1816–26. http://dx.doi.org/10.1080/10473289.2005.10464781.
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Kouremenos, D. A., C. D. Rakopoulos, and D. Hountalas. "Thermodynamic Analysis of Indirect Injection Diesel Engines by Two-Zone Modeling of Combustion." Journal of Engineering for Gas Turbines and Power 112, no. 1 (January 1, 1990): 138–49. http://dx.doi.org/10.1115/1.2906468.
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This work presents a thermodynamic analysis of a naturally aspirated, four-stroke, diesel engine with a swirl prechamber, under firing conditions during the open and closed part of the cycle. For calculating the heat exchange between gas and walls in both the main chamber and (swirl) prechamber, the relevant characteristic velocities and lengths are calculated by setting up a zero-dimensional energy cascade turbulence model. One-dimensional, quasi-steady, compressible flow with heat transfer inside the throat passageway connecting the two chambers is used. Combustion in both the main chamber and the swirl prechamber is attacked by proposing a two-zone combustion model, and following the movement of the spray plume inside an air solid body rotation environment in the prechamber and its later progression into the main chamber through the connecting throat. To validate the analysis, an extensive experimental investigation is undertaken at the laboratory of the authors on a flexible Ricardo, single-cylinder, swirl chamber diesel engine, and evaluating its performance in a wide range of operating conditions. The experimental results are found to be in good agreement with the theoretical results obtained from the computer program implementing the analysis.
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DATCU, Raluca, Andreea MIHALACHE, Andreea MUCIBABICI, and Andreea STAN. "Călătorind printr-o harpă – amenajarea unui portic." Argument. Spațiul construit. Concept și expresie, no. 10 (2018): 261–72. http://dx.doi.org/10.54508/argument.10.15.
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As far as today’s civilization development environment is concerned, man is living in an uninterrupted sound environment. Everywhere he is accompanied by a multitude of sounds and noises of varying intensity, having more or less violent effects on his hearing and his health. We can define noise as a representation of the sound vibration, not having a systematic attribute that is transmitted through various environments (air, water etc.) and that sensitizes the human ear negatively. In the Larousse dictionary, noise is a harmless sound system. Scientists with a specialization in physics characterize noise as a chaotic overlap with different frequencies and intensities, and physiologists appreciate the noise as any disturbing sound that causes an unpleasant sensation. It is proposed to revitalize the portico on street Ion Câmpineanu number 25, which hosts the entrance to a music shop. At present, it is a non-hostile and dark space dominated by massive pillars and shades of gray. Intervention involves the creation of a dynamic and interactive space in which the passageway is stimulated visually, tactile and auditory. With this solution, we want the public space in the studied area to develop a particular ambiance and vibration, allowing passers-by, hearing a harp melody, or even creating one’s own.
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Truman, J., J. Ewer, and E. Ball. "Dynamics of cyclic GMP levels in identified neurones during ecdysis behaviour in the locust Locusta migratoria." Journal of Experimental Biology 199, no. 4 (April 1, 1996): 749–58. http://dx.doi.org/10.1242/jeb.199.4.749.
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A grasshopper hatches from its egg, which is laid in soil, as a vermiform larva. This larva continues the stereotyped hatching behaviour as it digs through the egg pod, which provides a passageway to the soil surface. Once at the surface, shedding, or ecdysis, of the vermiform cuticle is initiated. When this process is complete, the first-instar cuticle is expanded to assume the form of the first-instar hopper. We have demonstrated, using immunocytochemical techniques, that these behaviour patterns are associated with dramatic increases in intracellular levels of cyclic GMP in sets of identified neurones in the ventral central nervous system. The most prominent cyclic-GMP-expressing cells are 34 neurones that appear to contain crustacean cardioactive peptide (CCAP). These CCAP cells show no detectable cyclic GMP at hatching or while the vermiform larva digs through the soil. Upon reaching the surface and freeing itself, the larva initiates ecdysis and associated air-swallowing and tracheal filling within about 1 min. These changes are immediately preceded by the appearance of cyclic GMP in the CCAP cells. Cyclic GMP levels in these neurones peak by 5 min and then decline back to basal levels by 20-30 min. Conditions that cause ecdysing animals to resume digging prolong the elevation of cyclic GMP levels. Once animals have assumed their 'hopper' form, however, external stimuli can no longer affect the time course of the cyclic GMP response. The neurones containing elevated cyclic GMP levels probably influence the air-swallowing, tracheal filling and circulatory changes that are associated with ecdysis behaviour. Pairs of descending midline neurones in abdominal segments 2-4 also become cyclic-GMP-immunoreactive, but they show peak expression after cyclic GMP levels in the CCAP cells have declined. Also, neurones in the caudolateral region of the abdominal ganglia often become cyclic-GMP-immunoreactive when ecdysing animals are forced to resume digging for an extended period.
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LaComb, Chase O., Richard D. Tandy, Szu Ping Lee, John C. Young, and James W. Navalta. "Oral versus Nasal Breathing during Moderate to High Intensity Submaximal Aerobic Exercise." International Journal of Kinesiology and Sports Science 5, no. 1 (January 31, 2017): 8. http://dx.doi.org/10.7575//aiac.ijkss.v.5n.1p.8.
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Introduction: When comparing oral breathing versus nasal breathing, a greater volume of air can be transported through the oral passageway but nasal breathing may also have benefits at submaximal exercise intensities. Purpose: The purpose of this study was to determine breathing efficiency during increasing levels of submaximal aerobic exercise. Methods: Nineteen individuals (males N=9, females N=10) completed a test for maximal oxygen consumption (VO2max) and on separate days 4-min treadmill runs at increasing submaximal intensities (50%, 65%, and 80% of VO2max) under conditions of oral breathing or nasal breathing. Respiratory (respiration rate [RR], pulmonary ventilation [VE]), metabolic (oxygen consumption [VO2], carbon dioxide production [VCO2]) and efficiency measures (ventilatory equivalents for oxygen [Veq×O2-1] and carbon dioxide [Veq×CO2-1] were obtained. Data were analyzed utilizing a 2 (sex) x 2 (condition) x3 (intensity) repeated measures ANOVA with significance accepted at p≤0.05. Results: Significant interactions existed between breathing mode and intensity such that oral breathing resulted in greater RR, VE, VO2, and VCO2 at all three submaximal intensities (p<.05). Veq×O2-1 and Veq×CO2-1 presented findings that nasal breathing was more efficient than oral breathing during the 65% and 80% VO2max intensities (p<0.05). Conclusion: Based on this analysis, oral breathing provides greater respiratory and metabolic volumes during moderate and moderate-to-high submaximal exercise intensities, but may not translate to greater respiratory efficiency. However when all variables are considered together, it is likely that oral breathing represents the more efficient mode, particularly at higher exercise intensities.
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Glaser, Dan R., Katrina Burch, Dennis L. Brinkley, and Philip Reppert. "Localization of deep voids through geophysical signatures of secondary dewatering features." GEOPHYSICS 86, no. 3 (May 1, 2021): WA139—WA152. http://dx.doi.org/10.1190/geo2020-0491.1.
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Discrete deep targets are a significant challenge for most surface-based geophysical techniques, even when considering high property contrasts. In general, surface-based geophysical methods lose lateral and vertical resolution with depth as a result of the limited acquisition geometry and increased signal attenuation. The former can be overcome through use of cross-borehole methods, but lateral localization is still needed for optimal borehole placement. As such, a relatively small, deep void located near the maximum depth of investigation (DOI) is very unlikely to be detected. Yet, secondary features associated with these voids can be exploited for enhanced detection performance. When voids are located below the groundwater table, a significant amount of dewatering and pumping is required to make them a functional passageway. This dewatering not only removes water from the void space but also the surrounding formation, resulting in a much larger, if more diffuse, secondary target: an induced groundwater table gradient. Many geophysical sensing methods are sensitive to subsurface moisture content. We have implemented a 2D joint-petrophysical mixing model (JPM), using inverted electrical resistivity tomography (ERT) and inverted seismic refraction models to sense changes in the groundwater table gradient. Our results are validated using the depth to bedrock, groundwater-surface water information, ground-penetrating radar, and time-domain reflectometry methods. Our initial proof of concept is applied to a shallow area with a significant soil moisture gradient, through different surface soil types and bedrock. The 2D JPM results are used to generate an estimate of air, moisture, and matrix percent fractions in the investigation area, providing a clear delineation of the groundwater surface and associated gradient. This refined hydraulic gradient estimate can then be used to laterally locate a void at or below the DOI of ERT and seismic refraction.
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Zhou, Xiao Jun. "Study on Structural Design and Driving Process of Subway Station Passageway Crossing Urban Trunk Road by Tunneling Method." Advanced Materials Research 919-921 (April 2014): 887–90. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.887.
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On the basis of unfavorable geology of a passageway in subway station to cross urban trunk road with heavy traffic flow in Chengdu city, the comparison of two different driving methods for the underground passageway with three arches and two pillars is carried out in the paper. The result shows that both center drift-pillar method and partial bench-cut method can be used to build the passageway in the subway station. But the latter is superior to the former in reducing construction cost, risk and timescale. While the former is more efficient in controlling ground subsidence. The tubular roof protection is also designed to reinforce the shear strength of soil above the crown of the passageway before excavating the poor surrounding soil. The inventive driving procedure of partial bench-cut method presented in the paper can be utilized to guide the rational design and economical construction of shallow passageway for subway station to cross urban trunk road in weak geological strata.
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E, Jia Qiang, Rong Jia Zhu, Hong Yan Zuo, Yan Ping Long, and Xiao Feng Hu. "Simulation and Analysis on Heat Transfer Performance of Oscillating Heat Pipe with Single and Double Passageway." Advanced Materials Research 516-517 (May 2012): 433–37. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.433.
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A relative full-scale numerical simulation has been conducted on oscillating heat pipe(OHP) with single passageway(S-OHP)and double passageway(D-OHP). Mathematical model for studying the influence on the heat transfer performance of the number of passageway was built, including turbulence model, volume of fluid model, continue surface force model, and heat and mass transfer model caused by phase change, and all of which were based on the consideration of gas-liquid interface, wall adhesion angle, surface tension and process of phase change. Results showed that, on the one hand, strong coherence of the initial gas-liquid distribution, as well as the flow phenomena during boiling stage, were found between S-OHP and D-OHP, on the other hand, the heat-transfer capability of the D-OHP is slightly higher than the S-OHP.
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Cao, Yi, Zhong Yi Zuo, and Hui Zhi Xu. "Research on Pedestrian Crossing Characteristics and Crossing Facilities of University's Passageway." Advanced Materials Research 859 (December 2013): 261–65. http://dx.doi.org/10.4028/www.scientific.net/amr.859.261.
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In order to adapt to the particularity of pedestrian crossing of universitys passageway, as well as relief the conflict between pedestrians and vehicles, the pedestrian crossing characteristics and crossing facilities were studied. Taking Huanghe road segment near to the main entrance of Dalian Jiaotong University as the investigation object, the pedestrian crossing and vehicle operating characteristics were investigated. By the method of mathematical statistics, the pedestrian crossing characteristics at peak and off-peak period were compared and analyzed. Taking Dalian Jiaotong University as an example, based on the particularity of universitys pedestrian crossing, the design plan of pedestrian crossing facilities was proposed. The research shows that, there is an obvious time distribution characteristic in universitys pedestrian crossing. It is necessary to considerate this characteristic and security to plan pedestrian crossing facilities.
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Feng, Zeng Chao, Jiang Fang Wang, and Dong Zhao. "Effect of Rock Nonhomogeneous Characteristics on Threshold Permeability." Advanced Materials Research 243-249 (May 2011): 3217–22. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3217.
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Permeability is one of an important characteristic of rock materials. The connectivity of permeate passageways could be used by probability of threshold permeability for evaluation. In the foundation of micro CT scan figures of rock samples, nonhomogeneous density distribution of inner rock is studied and connectivity rough of rock by threshold permeability program is also calculated. And the results are: the distribution of rock permeate passageways is nonhomogeneity and the probability of rock threshold permeability is also greatly declined, which is determined not only by ratios of nonporous particles but also by space distribution styles of porous medium.
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Li, Zhi Yong, Jie Nian Yan, Guang Cheng Jiang, Shui Xiang Xie, Ying Jun Fu, Wei Wei Zang, and Shuai Wei Yang. "The Research on Smart Drill-In Fluid Design." Advanced Materials Research 146-147 (October 2010): 1075–79. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.1075.
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There are continuous high concerns on formation protection technology in international petroleum engineering field. The reservoir drill-in fluid (RDF) is the first non-native fluid to contact formation, and which influences directly the ultimate capacity of oil and gas well. The paper discusses the smart RDF design method based on conventional drilling fluid. The designed RDF system is characterized as good formation damage control, as well as the performance easily adjusted for field application. The technology combines ideal packing technology with active calcium carbonate to obtain low permeability filter cake, high return permeability and low initial flowing pressure. The sized calcium carbonates contribute to develop sealing zone for preventing filtrate and solids from invading into formation, and the organophilic passageway in filter cake (the active calcium carbonate) is favorable to open automatically passageway for oil and gas during production. Different modifiers used to ground calciumcarbonate surface modification are evaluated in laboratory. And the laboratory results show modified calcium carbonates are comfortable with conventional drilling fluids additives such as XC(Xanthan ), potassium polyacrylate(K-PAM), sodium carboxymethyl cellulose(Na-CMC).
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Wang, Wei, and Yuntao Liang. "Prevention and Control Technology for Harmful Toxic Gas Intrusion in High-Fire-Hazard-Risk Areas of Close-Distance Coal Seams." Journal of Chemistry 2020 (October 28, 2020): 1–12. http://dx.doi.org/10.1155/2020/9040825.
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Fire hazard-risk area in small coal pits can be found in the southern part of the Shigetai Coal Mine, a close-distance coal seam mining sector in the Shendong mining area, which is susceptible to the risk of harmful toxic gas intrusion, seriously threatening the safety of mining around the working surface. Aiming at this problem, a numerical model representing the mining activity on the close-distance coal seams was established to simulate the movement pattern of overlying strata and the development process of fractures based on the horizontal stress “normalization” technology. Also, the principal air-leak passageways were detected with the SF6 tracer analysis. On this basis, the influencing pattern of harmful toxic gas intruding into the working surface can be comprehensively analyzed, providing a basis for effectively preventing and controlling gas intrusion disasters. The research findings show that, after a lower coal seam has been mined, the caving zone ranges from 73 m to 94 m in height, and the fractured zone tends to develop all the way to the surface. Furthermore, shear fractures are the major passageways for air leakage, and the occurrence of gas intrusion disasters is basically taking place at the same time frame as the occurrence of roof weighting. Meanwhile, the harmful toxic gas intrudes the working surface through the fractures on the security coal pillars and shear fractures on the overlying strata. To prevent intrusion disasters from occurring, the applications of inorganic foaming and curing materials for filling were studied in combination with the actual engineering conditions. The construction grounds in sections where the fire hazard-risk area in small coal pits have not been stripped were drilled, and filling materials were poured into the goaf to create an isolation belt. As can be observed from the applied areas, constructing isolation belts to block the major air-leak passageways can effectively prevent the harmful toxic gases from intruding into the working surface, ensuring the safety of mining on the working surface.
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Zhu, Rong Sheng, Xiu Li Wang, Yun Long, Zhi Jun Yu, and Qiang Fu. "Transient Dynamic Characteristics Study on Reactor Coolant Pump in Variable Working Conditions." Advanced Materials Research 601 (December 2012): 258–64. http://dx.doi.org/10.4028/www.scientific.net/amr.601.258.
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For the study of the transient hydraulic characteristics and internal flow mechanism of the reactor coolant pump from designed conditions to off-designed conditions, using CFX software to simulate the variable flow transient characteristics of reactor coolant pump impeller passageway. The results show that: during the flow transition, the radial force of the impeller doesn’t rotate around the coordinates origin, but rotates around some point in the fourth quadrant, and radial forces of the guide vanes mainly distributes in the first and second quadrant, and radial forces of the volute completely distribute in the fourth quadrant. Because of the influence from the blade number, radial forces of the impeller and guide vanes are in obvious star distribution, meanwhile, because the pump body uses annular structure，the flow and velocity in the impeller passageway and the pressure distribution of the impeller export asymmetry radial force. During the transition to big flow, the radial force impact of the impeller and guide vane mainly shows in the direction of the offset and slightly decreasement of the change magnitude. The radial force on the volute moves down with the incensement of the flow, and the changes magnitude become larger. During the transition to small flow, radial forces bearing on impellers, guide vanes and the volute, whether on the size, direction or the change magnitude, have a significant change.
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Tang, Xi Ya. "Decorative Arts of Gates Detail Components in Chinese Traditional Architecture." Advanced Materials Research 860-863 (December 2013): 1237–43. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.1237.
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Gate decoration art is one of Chinese traditional architecture decoration. It not only has own structure form and material form of building passageway against with that of other nations in the world, but so is a cultural background miniature of Chinese nation, and it is a material carrier of folk culture and decorative pattern. Decorative arts of gates detail components in Chinese traditional architecture have contained abundant aesthetic value and cultural connotation, all of this endowed gate decoration art with secret oriental color.
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Fei, Rui Zhen, Li Min Peng, Cheng Hua Shi, and Wei Chao Yang. "Characteristics of Train Wind and Analysis of Personnel Safety in Double-Line Shield Tunnel." Applied Mechanics and Materials 444-445 (October 2013): 264–69. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.264.
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Based on the three-dimensional incompressible Navier - Stokes equations and the standard turbulent model, this paper develops a tunnel-air-train simulation model. Time-history variation rules and space distribution characteristics of train wind are studied at 200km per hour, and safety avoidance distance on evacuation passageways is further discussed. The results show that: Train wind is complex three-dimensional flow which is changed with time and space, since personnel safety may be threatened by train wind. Therefore, effective measures should be taken to avoid accidents.
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Zhu, Xue Jun, Xing Lin Wen, Jie Peng, Lin Hai Gao, and De Ming Qu. "Application Study on Technology of Closure by Curtain Grouting in Mine Two of Dongfeng Coal Mine." Advanced Materials Research 446-449 (January 2012): 2002–6. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2002.
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The closure is just a way to build an underground wall blocking water by curtain grouting, by which in the district rich in water of mine two of Dongfeng coal mine curtain grouting was done to closure the passageway of water, reduce the water, remove the threat from water disasters, and improve the operation conditions, to promote the safety in production and increase the economic efficiency and the social efficiency; at the same time, protect the valuable water resources in periphery of mining area, maintain the balance of ecological environment, was worth to be popularized.
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Zhang, Xin, Jie Xu, Jian Yuan Guo, and Yang Wang. "Study on Evacuation Facilities Bottleneck in Xizhimen Station with Simulation." Advanced Materials Research 706-708 (June 2013): 2044–47. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.2044.
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Urban Rail Transit (URT) is more and more popular with citizens. Evacuation capability of stations is concerned with their service levels. When emergencies occur, passengers' safety is threatened. 3-line Xizhimen Station is taken with M/G/c/c theory for an example. By analyzing evacuation capability of stairs and passageways, evacuation bottlenecks are found to improve the service level of Xizhimen subway station.
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Rodger, Johnny. "Welcome back to Junkspace! Performing infinity while confined in lockdown." Architectural Research Quarterly 24, no. 4 (December 2020): 383–86. http://dx.doi.org/10.1017/s1359135520000408.
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For months we have been locked out of Junkspace. So, who’s complaining? Confined to domestic spaces, #stayhome has given many of us a forced opportunity to rethink the type of spaces that are not only functional and useful, but that make us feel comfortable. Our own residential arena may have felt restrictive and even – for some – oppressive at times, but who would say that they truly missed their daily passage through the endlessly stale air of check-in desks, departure gates, and duty frees at the airport; the epic journeys through low ceiling corridors and passageways of railway terminals and subway stations; and the blinding hallucinatory proliferation of brands and franchises in malls…?
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Fan, Gang Wei, Dong Sheng Zhang, and Lei Zhou. "Fracture Zonation for Overlying Strata in Underground Mining of Shallow Coal Seam." Advanced Materials Research 594-597 (November 2012): 2607–11. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.2607.
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Overburden fractures are the passageways for water resource loss in underground mining. A new zonation for overburden movement was present through the analysis on hydraulic aperture and permeability according to numerical calculations. Fractured zone was divided into three parts, the upper, the middle and the lower and their heights were educed. In the bedding plane, end fracture development zone and middle fracture compaction zone were defined and their range was calculated out. The achievements can be used for water resource conservation and gas prevention or drainage, etc.
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Cheng, Hai Gen, Yan Wang, and Li Xie. "Optimization Analysis of Position and the Shape of the Pre-Setting Hole on Cast- In Situ Box Girder Roof." Advanced Materials Research 243-249 (May 2011): 2004–9. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.2004.
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By analyzing concrete crack on the roof caused by the pre-setting hole during the construction process of the pre-stressed concrete cast-in-situ box girder bridge, this paper, which uses segment integral analysis method by ANSYS finite element program, primarily takes into account different hole position and shapes. The result shows that different position and the shape of the pre-setting hole can be seemed as decisive factors in influencing stress near the hole. It can be concluded as: the pre-setting hole should set as far as possible from pre-stressed passageway and the pre-stressed rebar first, then the shapes of hole should use circular or take corner cut polygon. Ultimately, under the premise of normal used construction, it is considerable to strive as much as possible in narrowing down the dimension of the pre-setting hole.
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Höfer, Dirk, and Detlev Drenckhahn. "Cytoskeletal differences between stereocilia of the human sperm passageway and microvilli/stereocilia in other locations." Anatomical Record 245, no. 1 (May 1996): 57–64. http://dx.doi.org/10.1002/(sici)1097-0185(199605)245:1<57::aid-ar10>3.0.co;2-8.
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Zuo, Yu Yu. "Gas Turbine Engines Lubrication System Design." Advanced Materials Research 900 (February 2014): 773–76. http://dx.doi.org/10.4028/www.scientific.net/amr.900.773.
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There are many reasons for having a lubricant within the engine besides that of reducing friction. However scrupulously clean the engine is maintained, there will always be a small amount of dirt or impurities that find their way inside. That dirt must be removed before it can cause damage to bearings or block small oil passageways. The oil can be used to keep the engine clean by carrying dirt to the oil filter where it is strained out and where it remains until replacement of the filter. The majority of the bearings within the engine are manufactured from steel, a metal which would soon oxidize itself if it were not prevented from doing so by a liberal coating of oil, thus the lubricant will also minimise corrosion inside the engine.
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Xu, Yan, Zhen Shun Liu, and Wen Zhao. "Earth Pressure Analysis on Subway Deep Excavation near Arch Bridge Abutment." Advanced Materials Research 368-373 (October 2011): 2955–59. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.2955.
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Subway construction involves a large number of excavation engineering. For the restrictions caused by conditions on the spot,Many foundation pits projects showed some features of clear spatial effects, complex stress characteristics,multiplex affecting factors, it often can not be suit for the applicable conditions of the existed earth pressure theory very well. On the background of BeiLing Station Passageway construction in Shenyang Subway Line No.2, Through counting and analyzing the results of three-dimensional numerical simulation in detail,summing up regulations of Taishan bridge abutment displacement in the horizontal plane. Force act on 4,5foundations fender post present trapezium and parabola distribution with depth respectively. So it is concluded the properties of foundation pit earth pressure, proposing a simple calculating model comparing its results with numerical simulation results to verify the reasonableness of the model. So the problem which is how to calculate the earth pressure under the complexity of obvious spatial effects and a variety of environmental conditions can be solved and reference experiences on the calculation of earth pressure can be provided to similar Follow-up projects
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Mao, Fei, Jian Xin Tang, Jiao Jiao Peng, and Zhi Qiang Li. "Features of Coal Pore & Fracture in Chuandong and their Relationship with Extra-Low Permeability." Advanced Materials Research 594-597 (November 2012): 2636–39. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.2636.
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The comparative datas from home and abroad indicate that extra-low permeability of coal seam is the basic reason why the gas outbursts obviously demonstrate three features in Chuandong. Further analysis on the microstructure of coal pore and fracture show that, firstly，the quantity of micro pores is much more than that of macro pores; the total volume of the pores is large while the volume of interconnected pores is small. This is helpful to gas storage but going against gas flow. Secondly, fracture density varys with magnification; there are many short fractures but only a few long fractures; all of the fractures are similar in width and in the form of zigzag; the directivity of fracture extension is irregular. Thirdly, fracture fillings are mainly hard inorganic matters. It is put forward that both pressure sensitive effect and water sensitivity effect exist in the coal seam and they are "double-edged swords" to permeability. In order to increase the permeability, it is necessary to change passive exhausting into active driving, remove gas reservoir and provide the passageway for gas dissipation.
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Topczewska, Jadwiga, and Anna Rogowska. "Assessment of housing conditions in selected horse stables." Roczniki Naukowe Polskiego Towarzystwa Zootechnicznego 13, no. 4 (December 28, 2017): 67–75. http://dx.doi.org/10.5604/01.3001.0013.5204.
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The objective of the study was to assess housing conditions for horses. Both new and adapted stables were selected for the study. Measurements of the buildings were made, the area of the boxes was calculated, and the equipment was evaluated. The microclimate of the stables was evaluated by means of direct measurements in the boxes and in the corridors in six replications, at 7 am, 2 pm and 7 pm, taking into account the season of the year. The temperature, relative humidity and air speed were measured with a Kastrel 3000 anemometer, and light intensity with a TES-1335 light meter. The concentration of gaseous impurities (CO2, H2S and NH3) was measured with a GAS-HUNTER meter. The results obtained were statistically analysed using STATISTICA 10.0. Several of the boxes in the adapted sheep building did not have the recommended minimum area of 9 m2, and also had smallest the cubic area per head. The air temperature was within the recommended range, but in one of the stables a temperature of 4°C was recorded in winter. The air movement in the passageways exceeded the recommended levels due to aeration through open doors. The skylights in the stable located next to the riding halls improved the natural lighting. In contrast, the stable adapted from a sheep building, with its low ceiling and small windows, was dimly lit and required artificial lighting. Despite the significant differences in the construction of the buildings, when they were erected, and the size of the stud, the microclimatic conditions were not found to differ significantly from the recommended standards.
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Lei, Wenjun, Zhanjiang Zheng, Chuanliang Rong, Chuanmin Tai, Shengzhong Zhao, and Angui Li. "Study on fire smoke control in evacuation passageways on the top floor of an atrium involving breathing zones combined with underfloor makeup air supplementation." Safety Science 153 (September 2022): 105807. http://dx.doi.org/10.1016/j.ssci.2022.105807.
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Conhaim, R. L., A. Eaton, N. C. Staub, and T. D. Heath. "Equivalent pore estimate for the alveolar-airway barrier in isolated dog lung." Journal of Applied Physiology 64, no. 3 (March 1, 1988): 1134–42. http://dx.doi.org/10.1152/jappl.1988.64.3.1134.
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In high-pressure pulmonary edema, lung interstitial and air space edema liquids have equal protein concentrations (Am. J. Physiol. 231: 1466, 1976). This suggests that the alveolar-airway barrier separating the air and interstitial spaces is relatively unrestrictive, even without apparent epithelial injury. To estimate the equivalent pore population of the alveolar-airway barrier we inflated each of 18 isolated dog lung lobes for 1 h with a solution of colored tracer of uniform radius. Tracer radii ranged from 1.3 to 405 nm. After freezing the lobes in liquid N2, we measured interstitial tracer concentrations in frozen perivascular cuffs or in samples thawed after dissection from frozen cuffs. Relative to the concentrations instilled, interstitial concentrations ranged from 0.34 for the smallest particles (1.3 and 3.5 nm radius) to zero for particles with radii of 405 nm. From the results we designed a pore model of the alveolar-airway barrier to reproduce the concentrations we measured. No single-pore model could be obtained, although a three-pore model fit the data well. The model results predict that pores with radii of 1, 40, and 400 nm would account for 68, 30, and 2% of total liquid flux, respectively. The majority of liquid flux (68%) would occur through passageways smaller than the smallest tracer we used (1.3 nm radius). We believe the alveolar-airway barrier consists not only of tight intercellular junctions that allow passage of only water and electrolytes but also of a smaller number of large leaks that allow passage of particles up to nearly 400 nm in radius.
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Zhu, Ming Zhi, Xiao Juan Chen, Mei Cong Wang, Wen Kai Wu, Gang Chen, and Bao Xu Wang. "General Structure Layout and Design of Target Area of SGIII Facility." Advanced Materials Research 765-767 (September 2013): 286–90. http://dx.doi.org/10.4028/www.scientific.net/amr.765-767.286.
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ShenGuang III (SGIII) facility will be constructed for research in Inertial Confinement Fusion. In this paper, general structure layout and design of target area of SGIII facility are described. Target area structure support system must provide a stable and precisely platform for optical elements before and during a shot. General structure layout must satisfy the mul-function consideration and logistic priority. The modularity and hardware commonality, cleanliness, and low neutron activation should be considered in the structural design of target area. The general structure layout of target area is rectangle. The target bay and the switchyard have the multi-layered layout to satisfy the demand of transporting beam lasers unidirectionally from south to north and supporting the optics modules and physical diagnostic instruments with different height. The passageways of population & goods flow of target area are designed to include the vertical channels between the different layers and the horizontal channels on the same layer. The opto-mechanical elements (OM) are classified as OM1, OM2, and OM3. The OM1 are the infrastructures. The OM2 include target chamber, the shell of final optics assemblies, the mirror frames, and the beam enclosures. The OM3 is line replaceable units that are attached to the OM2 on kinematic equivalent three-vee mounts.
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Antipatis, Christos, Cheryl J. Ashworth, George Grant, Richard G. Lea, Susan M. Hay, and William D. Rees. "Effects of maternal vitamin A status on fetal heart and lung: changes in expression of key developmental genes." American Journal of Physiology-Lung Cellular and Molecular Physiology 275, no. 6 (December 1, 1998): L1184—L1191. http://dx.doi.org/10.1152/ajplung.1998.275.6.l1184.
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Vitamin A is required during pregnancy for fetal lung development. These experiments monitored fetal lung morphology in normal and vitamin A-deficient rats. The expression of elastin and the growth arrest-specific gene 6 ( gas6) in fetal and neonatal hearts and lungs was assessed by Northern blotting. In normal-fed rats, elastin and gas6 were expressed in the fetal lung and heart from day 19 of gestation up to day 2 postnatally. Maternal vitamin A deficiency altered fetal lung development. On day 20, the bronchial passageways were less developed and showed reduced staining for elastic fibers, and in the neonates, the relative air space and the size of the sacculi were reduced. In the fetal lung, the mRNAs for elastin and gas6 were reduced to 56 and 68% of the control values, respectively. In the fetal heart, the mRNA for elastin was reduced to 64% of the control value, whereas gas6 was increased twofold. In the neonate, there was no change in elastin expression in the lung or heart, but gas6 expression in the heart was increased twofold. These results suggest that, in the pregnant rat, vitamin A deficiency may retard fetal lung development or influence the differentiation of critical cell lines. The changes in elastin and gas6 expression may be used to identify the cell types affected.
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Dyko, M. P., and K. Vafai. "Fundamental Issues and Recent Advancements in Analysis of Aircraft Brake Natural Convective Cooling." Journal of Heat Transfer 120, no. 4 (November 1, 1998): 840–57. http://dx.doi.org/10.1115/1.2825903.
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A heightened awareness of the importance of natural convective cooling as a driving factor in design and thermal management of aircraft braking systems has emerged in recent years. As a result, increased attention is being devoted to understanding the buoyancy-driven flow and heat transfer occurring within the complex air passageways formed by the wheel and brake components, including the interaction of the internal and external flow fields. Through application of contemporary computational methods in conjunction with thorough experimentation, robust numerical simulations of these three-dimensional processes have been developed and validated. This has provided insight into the fundamental physical mechanisms underlying the flow and yielded the tools necessary for efficient optimization of the cooling process to improve overall thermal performance. In the present work, a brief overview of aircraft brake thermal considerations and formulation of the convection cooling problem are provided. This is followed by a review of studies of natural convection within closed and open-ended annuli and the closely related investigation of inboard and outboard subdomains of the braking system. Relevant studies of natural convection in open rectangular cavities are also discussed. Both experimental and numerical results obtained to date are addressed, with emphasis given to the characteristics of the flow field and the effects of changes in geometric parameters on flow and heat transfer. Findings of a concurrent numerical and experimental investigation of natural convection within the wheel and brake assembly are presented. These results provide, for the first time, a description of the three-dimensional aircraft braking system cooling flow field.
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CHERNYH, O. N., and A. V. BURLACHENKO. "Assessment of the kinematic structure of the flow behind the well of a buried type of downstream AIC culverts." Prirodoobustrojstvo, no. 1 (2022): 34–40. http://dx.doi.org/10.26897/1997-6011-2022-1-34-40.
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The purpose of the investigation is to study the operating conditions of the downstream of the low-pressure conjugation and water passageway structures of the reclamation complex of the agro-industrial complex (AIC) in relation to the structural scheme of culvert sections operating in the conditions of the conjugation of the pools by the type of a submerged jet in the presence of a deep, relatively short stilling well. A brief description of the laboratory installation, the measuring equipment used to record turbulent fl ow characteristics and the methodology for performing model studies is given. The results are given on fi nding and studying rational downstream structures and devices (hearth, baffl es, apron) taking into account pulsating fl ow effects on the fastening elements. The fl ow modes behind the culvert structure and spillway dam with a deep well have been established, calculated dependences are given to determine its optimal parameters and assess the average and pulsation components of pressure on the main elements of the downstream devices. On the model operating at the Reynolds numbers over 10000 and Froude numbers in the compressed section from 20 to 120, a design was chosen that provides the greatest energy baffl e effect at the angle of the turbulent jet entry into the well varying within 50°…70°, which includes blocks in addition to the deep short well. This made it possible to analyze the kinematic structure of the fl ow and reveal the intense attenuation of the pulsation component of the fl ow velocities and pressures along the length of the outlet channel by about 20% compared to a jump well of simple outlines, and a decrease in the planned irregularity of the diagrams. All this together confi rmed the effi ciency of the structure on the sloping sections of the reclamation network for the structures with a specifi c fl ow rate in the range of 0.15…5.5 m2 /s. As a result of the research carried out, the design of the device and downstream anchorage has been improved providing the necessary reliability of its operation.
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Jasztal, Michał. "Testing the Process of Evacuation from the Passenger Aircraft with the Use of Computer Simulation." Safety & Fire Technology 56, no. 2 (2020): 22–39. http://dx.doi.org/10.12845/sft.56.2.2020.2.
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Aim: The main aim of the study was to investigate the possibility to use the Pathfinder simulation software to determine the duration of an evacuation and to plan its course for various scenarios of evacuation organisation, for specific profiles and behaviours of passengers and on-board personnel, and for a specific geometrical arrangement of the passenger cabin of a selected passenger aircraft. In addition, the paper discusses selected factors that affect the evacuation from the passenger aircraft. Project and methods: The Pathfinder software used in the research has the graphical interface to create an evacuation simulation model (2D and 3D) as well as tools to visualise the results. Pathfinder is based on artificial intelligence algorithms, in which each passenger has a number of individual features that can influence his/her movements and decisions during the simulation. The simulation of people's movement is determined by their profiles and behaviours, the parameters of which can be entered by means of probability distributions, which makes it possible to take into account the stochastic nature of the evacuation process. Results: The Boeing 787 Dreamliner was selected for the study, for which six options for simulating the evacuation of 252 passengers and eight members of on-board personnel were conducted. The shortest evacuation time was achieved by changing the even distribution of the number of passengers to the individual emergency exits, thus avoiding congestions in sensitive areas of the passenger cabin. The increase in passengers' maximum speed has paradoxically increased evacuation times, as it has increased the intensity of passenger collisions. It was found that one of the key issues affecting the timing of an evacuation is the proper organisation of the evacuation by on-board personnel, who, by guiding passengers through the geometrically most advantageous passageways, results in the fastest possible evacuation. The simulations in variants five and six have achieved satisfactory evacuation times, which are within the emergency aircraft evacuation time limit required in a certification process. Conclusions: The presented simulation models, the results obtained, and the wide range of possibilities of three-dimensional visualisation of research results give a rational basis for the use of Pathfinder software for testing the evacuation process and thus: for the usage in the aircraft design process, for preparing aircrafts for tests, for shaping evacuation procedures, for on-board personnel training and for air accident investigation.
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Sayahi, Emborg, Hedlund, and Cwirzen. "Plastic Shrinkage Cracking in Concrete." Proceedings 34, no. 1 (November 18, 2019): 2. http://dx.doi.org/10.3390/proceedings2019034002.
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Plastic shrinkage cracking in concrete is mainly a physical process, in which chemical reactions between cement and water do not play a decisive role. It is commonly believed that rapid and excessive moisture loss, due to evaporation is the primary cause of the phenomenon. Once the concrete is cast, its solid particles start to settle due to gravity, causing an upward water-flow from the concrete interior and through its pore system to the surface, i.e., bleeding regime. When the amount of the evaporated water exceeds the amount of the water accumulated at the concrete surface, i.e., bleed water, concrete enters the so called drying regime, during which water menisci form inside the pores causing a build-up of a negative pore pressure, also known as capillary pressure. The progressive evaporation gradually decreases the radii of the menisci, which causes a further increase of the pore pressure and solid particles consolidation. Eventually, the skeleton of the concrete becomes stiff enough to resist the gravitational forces, which means that the vertical deformation of the concrete either completely stops or continues at a much lower rate. At this point, the capillary pressure is no longer able to further consolidate the concrete and move the pore water towards the surface. Instead, the developed tensile forces reduce the inter particle distances and the horizontal deformation continues. If the concrete member is restrained (e.g., due to reinforcement, variation in sectional depth, the friction of the form, etc.), the shrinkage can lead to tensile stresses accumulation. Once the tensile stresses exceed the early age tensile strength of the concrete, cracks start to form, preparing passageways for ingress of harmful materials into the concrete interior, which eventually may impair the durability and serviceability of the structure. This abstract reports the findings of a PhD research, carried out at Luleå University of Technology (LTU) to investigate the impact of parameters such as, admixtures, water-cement ratio (w/c), cement type, dosage of superplasticizer (SP), and steel fibers, on concrete’s cracking tendency while in plastic state. The results show that presence of accelerators, retarders, coarser cement particles, high w/c, and more SP increases the cracking risk, while stabilizers, air entraining agents (AEA), shrinkage reducing admixtures (SRA), and steel fibers notably decrease the cracking potential. Based on the findings of the above mentioned investigation a new model is proposed to estimate the severity of plastic shrinkage cracking, based on the initial setting time and the amount of the evaporated water from within the concrete bulk. The experimental results of the PhD research, alongside those reported by other researchers, were utilized to check the validity of the proposed model. According to the outcomes, the model could predict the cracking severity of the tested concretes with a good precision.
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Baghlad, Faddia, Benouada Douaiba, and Abbes Azzi. "AERODYNAMIC EFFECTS OF POLLUTION CONCENTRATIONS IN URBAN STREET CANYON USING TWO PASSIVE CONTROL METHODS: CROSSING UNDER BUILDING AND LOW BOUNDARY WALL." Journal of Urban and Environmental Engineering, October 5, 2019, 13–22. http://dx.doi.org/10.4090/juee.2019.v13n1.013022.
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The present work, focused on the Atmospheric boundary-layer airflows and their interactions with obstacles, particularly in relation to urban air quality, therefore two passive control methods are represented in barriers solid LBWs (Low Boundary Walls) and crossings under building, in order to investigate the dynamic impacts in the center urban canyon road. These passive control solutions are designed for reducing the concentrations airflows polluted necessary, while a correct air quality in the urban areas. For these reasons, the passageways under building and LBWs models have been performed with a two dimensional numerical ANSYS-CFX code, rendering it ideal for examining the concentration distribution within street canyons of H1/H2 = 0.5-1-1.5 and the dynamics effects of pollution concentrations of vehicle emissions of sulfur hexafluoride (SF6), which it is taken as a tracer gas within the symmetrical urban street canyon. However the Reynolds-averaged Navier–Stokes equations and the k-ɛ turbulence model are applied in order to close the equations system. The results achieved are evidence about the diminishing of the pollutant concentrations normalized in in the leeward and windward of the urban street canyon
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Allen, Cody W., Chad M. Holcomb, and Maurício de Oliveira. "Estimating Recoverable Performance Degradation Rates and Optimizing Maintenance Scheduling." Journal of Engineering for Gas Turbines and Power 141, no. 1 (November 14, 2018). http://dx.doi.org/10.1115/1.4041004.
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Many of the components on a gas turbine are subject to fouling and degradation over time due to debris buildup. For example, axial compressors are susceptible to degradation as a result of debris buildup on compressor blades. Similarly, air-cooled lube oil heat exchangers incur degradation as a result of debris buildup in the cooling air passageways. In this paper, we develop a method for estimating the degradation rate of a given gas turbine component that experiences recoverable degradation due to normal operation over time. We then establish an economic maintenance scheduling model, which utilizes the derived rate and user input economic factors to provide a locally optimal maintenance schedule with minimized operator costs. The rate estimation method makes use of statistical methods combined with historical data to give an algorithm with which a performance loss rate can be extracted from noisy data measurements. The economic maintenance schedule is then derived by minimizing the cost model in user specified intervals and the final schedule results as a combination of the locally optimized schedules. The goal of the combination of algorithms is to maximize component output and efficiency, while minimizing maintenance costs. The rate estimation method is validated by simulation where the underlying noisy data measurements come from a known probability distribution. Then, an example schedule optimization is provided to validate the economic optimization model and show the efficacy of the combined methods.