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Search Results: 1 - 10 of 18828 matches for " Flow rate "
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Possibility of a Straightening Flow-Meter by Using Woven Screen  [PDF]
Takahiro Tsuchiya, Yota Koishi, Mitsuo Iwamoto, Hidemi Yamada
Open Journal of Fluid Dynamics (OJFD) , 2015, DOI: 10.4236/ojfd.2015.51005
Abstract: In this paper, the possibility of the flow rate measurement for a circular pipe flow by using a wo-ven screen with the property of straightening un-uniform flows is discussed. The resistance coefficient and the flow rate coefficient are estimated from the pressure difference caused by the woven screen under the experiment ranges of the wire Reynolds number, Red = 2.2 × 102-1.8 × 103, and of the open area ratio, β = 0.28-0.65. As a result, the resistance coefficient decreases and the flow rate coefficient increases as the wire Reynolds number Red or the open area ratio β increases. In addition, both coefficients are not affected by the difference between uniform and turbulent pipe flows approaching the woven screen. Therefore, the possibility of a flow-meter having the property to straighten the un-uniform flow is expected.
Pico de flujo espiratorio en ni?os uruguayos sin enfermedad, de 3 a 13 a?os
Revista chilena de pediatría , 2007, DOI: 10.4067/S0370-41062007000400016
Abstract: since the early nineties, the peak expiratory flow (pfe) has been included in consensus recommendations on control and treatment of asthma. due to the fact that the pfe presents with variations in different populations, the values for pfe were determined in healthy uruguayan children. three hundred and sixty two boys and 437 girls from 9 different schools, without prior history of respiratory disease, use of respiratory pfe were determined using a vitalograph flowmeter in standing position, and the highest value of 3 or more procedures was recorded. the children were studied grouped by gender and in weight intervals of 5 kg, length intervals of 10 cm and age intervals of 1 year. the percentile 10, 50 and 90 were determined for each class interval and was correlated with a 2nd degree polinomial function. the correlation coefficient (r2) for percentiles 10, 50 and 90 was of 0,99, 0,98, and 1,00 in the case of length, being a little less in case of age and weight. the values of pfe were greater for boys in comparison to girls from 40 kg onwards, an age of 9 years and length of 140 cm. the values obtained in this study were compared with those previously published
Muhammad Inayatullah
The Professional Medical Journal , 2000,
Abstract: OBJECTIVE: To find out normal values of PEFR in the healthy population of Multan region. DESIGN:Epidemiological survey. PERIOD: Feb to May 1996. MATERIAL AND METHODS: PEFR was measuredin a total of 4000 healthy individuals (2643 males and 1357 female) above the age of 13 years from varioussections of population. RESUTLS: Mean value of PEFR was 475 ± 73.0 litre per minute for male and 247± 78.8 litre per minute for female. There was no significant correlation with height and age in both sexes.
Modification of water application uniformity among closed circuit trickle irrigation systems  [PDF]
Hani A.-G. Mansour, Mohamed Yousif Tayel, Mohamed A. Abd El-Hady, David A. Lightfoot, Abdel-Ghany Mohamed El-Gindy
Agricultural Sciences (AS) , 2010, DOI: 10.4236/as.2010.11001
Abstract: The aim of this research was determine the ma- ximum application uniformity of closed circuit trickle irrigation systems designs. Laboratory tests carried out for Two types of closed circuits: a) One manifold for lateral lines or Closed circuits with One Manifold of Trikle Irrigation System (COMTIS); b) Closed circuits with Two Manifolds of Trikle Irrigation System (CTMTIS), and c) Traditional Trikle Irrigation System (TTIS) as a control. Three lengths of lateral lines were used, 40, 60, and 80 meters. PE tubes lateral lines: 16 mm diameter; 30 cm emitters distance, and GR built-in emitters 4 lph when operating pressure 1 bar. Experiments were conducted at the Agric. Eng. Res. Inst., ARC, MALR, Egypt. With COMTIS the emitter flow rate was 4.07, 3.51, and 3.59 lph compared to 4.18, 3.72, and 3.71 lph with CTMTIS and 3.21, 2.6, and 2.16 lph with TTIS (lateral lengths 40, 60, and 80 meters respectively). Uniformity varied widely within individual lateral lengths and between circuit types. Under CTMTIS uniformity values were 97.74, 95.14, and 92.03 %; with COMTIS they were 95.73, 89.45, and 83.25 %; and with TTIS they were 88.27, 84.73, and 80.53 % (for lateral lengths 40, 60, 80 meters respectively). The greatest uniformity was observed under CTMTIS and COMTIS when using the shortest lateral length 40 meters, then lateral length 60 meters, while the lowest value was observed when using lateral length 80 meters this result depends on the physical and hydraulic characteristics of the emitter and lateral line. CTMTIS was more uniform than either COMTIS or TTIS. Friction losses were decreased with CTMTIS in the emitter laterals at lengths 40 meters compared to TTIS and COMTIS. Therefore, differences may be related to increased friction losses when using TDIS and COMDIS.
Direct Calculation of Unsteady-State Weymouth Equations for Gas Volumetric Flow Rate with Different Friction Factors in Horizontal and Inclined Pipes  [PDF]
Abayomi O. Olatunde, Tunde A. Adeosun, Mohammed A. Usman, Olabisi M. Odunlami, Moses A. Olowofoyeku, Testy E. Ekakitie, Atanda M. Mohammed
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.44027
Abstract: Direct calculations of unsteady-state Weymouth equations for gas volumetric flow rate occur more frequently in the design and operation analysis of natural gas systems. Most of the existing gas pipelines design procedures are based on a particular friction factor and steady-state flow analysis. This paper examined the behavior of different friction factors and the need to develop model analysis capable of calculating unsteady-state gas flow rate in horizontal and inclined pipes. The results show different variation in flow rate with Panhandle A and Panhandle B attaining stability in accurate time with initial unsteadiness at the instance of flow. Chen and Jain friction factors have opposition to flow with high flow rate: The prediction also reveals that Colebrook-White degenerated to Nikuradse friction factor at high Reynolds number. The horizontal and inclined flow equations are considerably enhanced on the usage of different friction factors with the aid of Matlab to handle these calculations.
Experimental and Numerical Study of Impact of Air Filter Holes Masking on Altitude at Heavy-Duty Diesel Engine  [PDF]
Sepideh Hosseinzadeh, Mofid Gorji-Bandpy, Ghasem Javadi Rad, Mojtaba Keshavarz
Modern Mechanical Engineering (MME) , 2012, DOI: 10.4236/mme.2012.24021

At high altitudes, power of an internal combustion engine reduces due to air density reduction. In turbocharged diesel engine this issue affects the performance of the compressor and can result in unstable operation of the turbocharger if the power is not decreased by engine actuator. Mainly for testing the effects of altitude in the test room, air throttle valve and combustion air handling unit were used to reduce the suction air pressure. Easier and cheaper solution to consider effect of altitude on engine performance is to mask part of the air filter to reduce the suction pressure. In this paper, pressure drop against 0%, 26%, 52%, 66% and 74% of air filter hole’s masking for different mass flow rates has been studied by computational fluid dynamics. The analysis output mass flow rate-pressure diagram for the air filter, will be used as input data in the GT-Power software which is a one-dimensional computational fluid dynamics software and the effect of masking on altitude and performance at different revolutions per minute of the engine is investigated. Also, an experimental and computational fluid dynamics study was carried out to predict altitude against different proportions of air filter hole’s masking at 1000 rpm. The predicted results are validated by comparing with those of experimental data. A good agreement between the predicted and experimental values ensures the accuracy of the numerical predictions with the present work.

The Influence of Sheath Solvent’s Flow Rate on the Quality of Electrospun Ethyl Cellulose Nanofibers  [PDF]
Deng-Guang Yu, Xiong-Xiu Li, Jia-Wen Ge, Peng-Peng Ye, Xia Wang
Modeling and Numerical Simulation of Material Science (MNSMS) , 2013, DOI: 10.4236/mnsms.2013.34B001

The present research investigates the influence of sheath solvent’s flow rate on the quality of electrospun ethyl cellulose (EC) nanofibers using a modified coaxial process. With 24 w/v % EC in ethanol as electrospinnable core fluid and ethanol as sheath fluid, EC nanofibers generated under different sheath flow rates were generated from the modified processes. FESEM observations demonstrate that the modified process is effective in preventing the clogging of spinneret for a smooth electrospinning. The key for the modified coaxial process is the reasonable selection of a sheath flow rate matching the drawing process of core EC fluid during the electrpospinning. The EC nanofibers’ diameters (D, nm) could be manipulated through the sheath-to-core flow rate ratio (f) as D = 819-1651f (R= 0.9754) within a suitable range of 0 to 0.25. The present paper provides useful data for the implementation of the modified coaxial process controllably to obtain polymer nanofibers with high quality.

Electrical Parameters Investigation and Zero Flow Rate Effect of Nitrogen Atmospheric Nonthermal Plasma Jet  [PDF]
T. M. Allam, S. A. Ward, H. A. El-sayed, E. M. Saied, H. M. Soliman, K. M. Ahmed
Energy and Power Engineering (EPE) , 2014, DOI: 10.4236/epe.2014.612036
Abstract: The construction and operation of atmospheric nonthermal plasma jet, ANPJ, are presented in this work as well as the experimental investigations of its electrical parameters, the configuration of plasma jet column and its temperature. The device is energized by a low-cost Neon power supply of (10 kV, 30 mA, and 20 kHz) and the discharge takes place by using N2 gas with different flow rates from 3 to 25 L/min and input voltage of 6 kV. Diagnostic techniques such as voltage divider, Lissajous figure, image processing and thermometer are used. The electrical characteristics of discharge at different flow rates of N2 gas such as discharge voltage, current, mean power, power efficiency, and mean energy have been studied. The experimental results show that the maximum plasma jet length of 14 mm is detected at flow rate of 12 L/min. The results of plasma jet (heavy particles) temperature along the jet length show that jet plasma has approximately a room temperature at the jet column end. The results of zero flow rate effect on the ANPJ operation show damage in the Teflon insulator and a corrosion in the Aluminum electrodes.
Profile Design and Numerical Calculation of Instantaneous Flow Rate of a Gerotor Pump  [PDF]
Hao Liu, Jae-Cheon Lee, Alex Yoon, Sang-Tae Kim
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.31013

Gerotor pump is a special kind of internal rotary pump, which contains a trochoid profile (commonly called as cycloid). Generation of trochoid is normally realized by external rolling method, namely a circle rotating on a fixed circle without slipping. This paper proposes derivative process of the trochoid profile by means of internal rolling method, which is that internal surface of a circle contacts with a fixed circle and rotates around it without slipping. Moreover the instantaneous flow rate can be obtained by numerically calculating the change ratio of area between the inner and outer rotors in the outlet region of the gerotor pump, which avoids to complicatedly derivative process.

Impact of Pedestrian Traffic on Saturation Rate of Protected Left-Turn at Urban Intersections  [PDF]
Yixin Chen, Yulong He, Xiaoduan Sun
Open Journal of Applied Sciences (OJAppS) , 2015, DOI: 10.4236/ojapps.2015.51003
Abstract: Heavily congested intersections in metropolitan areas in China are facing unique problems due to high travel demand and a high degree of traffic law violations. Based on a study conducted by the authors of this paper, 93% of left-turn vehicles turning left in these areas were slowed in order to avoid conflict with pedestrians. Intertwined pedestrian and vehicular flows can significantly reduce the capacity of exclusive left-turn lane group through reducing saturation flow rate, which increases the congestion at intersections. This paper investigates how the saturation flow rate of exclusive left-turn lane group is affected by the characteristics of pedestrian flow. By analyzing the imagery data collected by video cameras installed at intersections, the research team is able to obtain the characteristics of both vehicular and pedestrian flows, such as speed and spatial locations. The average operating speed at the saturation flow rate with and without pedestrian traffic is used as a direct measurement to evaluate the effect of pedestrians. Based on the statistical analysis, the paper concludes that saturation flow rate is mainly affected by the position of pedestrian in the crosswalk (inside or outside of left-turn vehicle’s trajectory), and the distance between the vehicle and pedestrians. In general, when the distance is less than four meters, the smaller the distance between vehicle and pedestrians, the larger the impact. However, there is no significant impact when the distance is larger than four meters. To accurately quantify the effect, the degree of pedestrian-vehicle impact is defined in four levels. The results show that the difference in the saturation flow rate between the best and the worst level could be 15.7%, which clearly indicates how important it is to enforce pedestrian crossing behavior.
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