scholarly journals Measurement of Permeability in Horizontal Direction of Open-Graded Friction Course with Rutting

2020 ◽  
Vol 12 (16) ◽  
pp. 6428
Author(s):  
Jaewon Yoo ◽  
Tan Hung Nguyen ◽  
Eungu Lee ◽  
Yunje Lee ◽  
Jaehun Ahn
Keyword(s):  
Hydraulic Gradient ◽  
Testing Equipment ◽  
Horizontal Direction ◽  
Flow Area ◽  
Cross Sectional ◽  
Traffic Loading ◽  
Test Methodology ◽  
Discharge Velocity ◽  
Open Graded Friction Course ◽  
Horizontal Permeability

Although the permeability of open-graded friction course (OGFC) materials in the transverse direction and the reduction in permeability associated with long-term traffic loading are important issues, they have remained under researched thus far. In this study, testing equipment and procedure were developed to evaluate the permeability of an OGFC specimen along the horizontal direction and its reduction due to rutting. Horizontal permeability tests were conducted by varying the hydraulic gradient of specimens with porosities of 19.6%, 15.6%, and 10.3%. The reduction in cross-section due to traffic loading was simulated via a wheel tracking test, and the permeability was subsequently evaluated. The reliability of test methodology was successfully verified; the tendency of the relationship between discharge velocity and hydraulic gradient was in good agreement with existing research results. The reduction in cross-sectional flow area due to rutting decreased and the horizontal permeability. The test results using developed testing equipment will enable efficient OGFC design.

scholarly journals Discharge Estimation Using Tsallis and Shannon Entropy Theory in Natural Channels

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1786
Author(s):  
Jitendra Kumar Vyas ◽  
Muthiah Perumal ◽  
Tommaso Moramarco
Keyword(s):  
Flow Velocity ◽  
Surface Flow ◽  
Tsallis Entropy ◽  
Accurate Estimation ◽  
Mean Flow ◽  
Flow Area ◽  
Cross Sectional ◽  
The Cross ◽  
Discharge Estimation ◽  
Mean Flow Velocity

Streamflow measurements during high floods is a challenge for which the World Meteorological Organization fosters the development of innovative technologies for achieving an accurate estimation of the discharge. The use of non-contact sensors for monitoring surface flow velocities is of interest to turn these observed values into a cross-sectional mean flow velocity, and subsequently, into discharge if bathymetry is given. In this context, several techniques are available for the estimation of mean flow velocity, starting from observed surface velocities. Among them, the entropy-based methodology for river discharge assessment is often applied by leveraging the theoretical entropic principles of Shannon and Tsallis, both of which link the maximum flow velocity measured at a vertical of the flow area, named the y-axis, and the cross-sectional mean flow velocity at a river site. This study investigates the performance of the two different entropic approaches in estimating the mean flow velocity, starting from the maximum surface flow velocity sampled at the y-axis. A velocity dataset consisting of 70 events of measurements collected at two gauged stations with different geometric and hydraulic characteristics on the Po and Tiber Rivers in Italy was used for the analysis. The comparative evaluation of the velocity distribution observed at the y-axis of all 70 events of measurement was closely reproduced using both the Shannon and Tsallis entropy approaches. Accurate values in terms of the cross-sectional mean flow velocity and discharge were obtained with average errors not exceeding 10%, demonstrating that the Shannon and Tsallis entropy concepts were equally efficient for discharge estimation in any flow conditions.

Nasal vestibule wall elasticity: interactions with a nasal dilator strip

1999 ◽  
Vol 86 (5) ◽  
pp. 1638-1643 ◽  
Author(s):  
T. C. Amis ◽  
J. P. Kirkness ◽  
E. di Somma ◽  
J. R. Wheatley
Keyword(s):  
Elastic Properties ◽  
Cross Sectional Area ◽  
Horizontal Direction ◽  
Sectional Area ◽  
Cross Sectional ◽  
Nasal Vestibule ◽  
Wall Displacement ◽  
Recoil Force ◽  
Wall Compliance

We studied the effect of an adhesive external nasal dilator strip (ENDS) on external nasal geometry in 20 healthy Caucasian adults (10 men, 10 women; age 21–45 yr). The recoil force exerted by ENDS was estimated by bending the device ( n = 10) with known weights. In the horizontal direction, a small/medium-sized ENDS in situ exerted a unilateral recoil force of 21.4–22.6 g. Application of ENDS resulted in a displacement of the lateral nasal vestibule walls that had both anterosuperior and horizontal components and that was maintained over an 8-h period. The resultant unilateral nasal vestibule wall displacement at the tip of the device was at 47.6 ± 2.0° to the horizontal (as related to the plane of the device when in situ) and had a magnitude of 3.5 ± 0.1 mm. ENDS increased external nasal cross-sectional area by 23.0–65.3 mm2. Nasal vestibule wall compliance was estimated at 0.05–0.16 mm/g. Thus ENDS applies a relatively constant abducting force irrespective of nasal width. Variable responsiveness to ENDS may be related to differences in elastic properties of the nasal vestibule wall.

Effect of Non Uniform Flow Distribution on Single Phase Heat Transfer in Parallel Microchannels

2007 ◽  
Author(s):  
Akhilesh V. Bapat ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Single Phase ◽  
Flow Distribution ◽  
Uniform Flow ◽  
Hydrodynamic Performance ◽  
Flow Area ◽  
Cross Sectional ◽  
Uniform Flow Distribution ◽  
Parallel Microchannels

The continuum assumption has been widely accepted for single phase liquid flows in microchannels. There are however a number of publications which indicate considerable deviation in thermal and hydrodynamic performance during laminar flow in microchannels. In the present work, experiments have been performed on six parallel microchannels with varying cross-sectional dimensions. A careful assessment of friction factor and heat transfer in is carried out by properly accounting for flow area variations and the accompanying non-uniform flow distribution in individual channels. These factors seem to be responsible for the discrepancy in predicting friction factor and heat transfer using conventional theory.

Laboratory Investigation of an Alternative Permeability Indicator to Determine Optimal Maintenance Timing for Open-Graded Friction Course

2020 ◽  
Vol 2674 (4) ◽  
pp. 165-177
Author(s):  
Shenghua Wu ◽  
Li Liu ◽  
Gang Yao ◽  
Juan Zhang ◽  
Omar Tahri
Keyword(s):  
Heavy Traffic ◽  
Low Impact Development ◽  
Traffic Loading ◽  
Measuring Device ◽  
Open Graded Friction Course ◽  
Optimal Maintenance ◽  
Air Void ◽  
Relationship Of ◽  
The Relationship

Open-graded friction course (OGFC) is a low impact development practice that provides a better pavement drainage solution and safer driving conditions. However, there exists a gap in understanding how internal pores in OGFC mix affect hydraulic conductivity, particularly when OGFC suffers the most rutting damage under the effects of high temperature and heavy traffic loading. There is also a lack of research on determining the optimal maintenance timing for an OGFC pavement. This study aims at characterizing the relationship of volumetric and permeability properties for OGFC slab specimens and quantifying permeability deterioration over time using a developed precipitation simulator and permeability measuring device and rutting test. Seven test temperatures (40, 45, 50, 55, 60, 65, and 70°C) were considered in the rutting test. The effect of clogging material size on permeability was also evaluated. The test results suggested that interconnected air void was lower than total air void, and higher rutting temperature resulted in reduced interconnected air void. The clogging experiment suggested that 0.3–0.6 mm material caused the most clogging while 0.075–0.15 mm material caused the least clogging. Based on this study, it is recommended to use a field measured rut depth as an alternative permeability indicator for determining optimal maintenance timing for an OGFC pavement using the correlation established between permeability and rut depth. A case study of OGFC pavement demonstrated that when the field measured rut depth reached 4.5 mm or higher, timely maintenance is needed.

scholarly journals A Non-Dimensional Conceptual Design Procedure for the Vaneless Volutes of Radial Inflow Turbines

1991 ◽  
Author(s):  
A. Whitfield ◽  
A. B. Mohd Noor
Keyword(s):  
Mach Number ◽  
Conceptual Design ◽  
Swirling Flow ◽  
Design Procedure ◽  
Area Ratio ◽  
Working Fluid ◽  
Flow Area ◽  
Cross Sectional ◽  
The Absolute ◽  
Inlet Conditions

The requirements for the volute of a radial inflow turbine are that it should collect the working fluid, deliver it to the turbine rotor as efficiently as possible and provide the desired rotor inlet conditions. The overall performance requirements of the turbine leads to the rotor design and the identification of the desired flow conditions at rotor inlet in terms of the magnitude and direction of the absolute Mach number, see Whitfield (1990). The volute must then be designed to ensure that the desired rotor inlet conditions are attained. A non-dimensional conceptual design procedure for a vaneless turbine volute is described. Based on a knowledge of the magnitude and direction of the absolute Mach number at rotor inlet the overall dimensions of the volute in terms of the radius ratio and flow area ratio are first established. The overall design is then developed to provide the variation of the volute centroid radius and area ratio with azimuth angle. A trapezoidal cross-sectional shape is then used to establish the outer dimensions of the volute. The non-dimensional design procedure assumes a one-dimensional compressible flow and as such relies on the empirical specification of the dissipation of angular momentum, the dissipation of energy, and the deviation of the swirling flow from that of a free vortex. The effect of the uncertainties associated with the empirical data on the volute design geometry is assessed.

scholarly journals Scale orientated analysis of river width changes due to extreme flood hazards

2011 ◽  
Vol 11 (8) ◽  
pp. 2137-2147 ◽  
Author(s):  
G. Krapesch ◽  
C. Hauer ◽  
H. Habersack
Keyword(s):  
Numerical Models ◽  
Width Ratio ◽  
Flood Hazards ◽  
Stream Power ◽  
Flow Area ◽  
Cross Sectional ◽  
Average Width ◽  
Extreme Floods ◽  
Mean Width ◽  
Extreme Flood

Abstract. This paper analyses the morphological effects of extreme floods (recurrence interval >100 years) and examines which parameters best describe the width changes due to erosion based on 5 affected alpine gravel bed rivers in Austria. The research was based on vertical aerial photos of the rivers before and after extreme floods, hydrodynamic numerical models and cross sectional measurements supported by LiDAR data of the rivers. Average width ratios (width after/before the flood) were calculated and correlated with different hydraulic parameters (specific stream power, shear stress, flow area, specific discharge). Depending on the geomorphological boundary conditions of the different rivers, a mean width ratio between 1.12 (Lech River) and 3.45 (Trisanna River) was determined on the reach scale. The specific stream power (SSP) best predicted the mean width ratios of the rivers especially on the reach scale and sub reach scale. On the local scale more parameters have to be considered to define the "minimum morphological spatial demand of rivers", which is a crucial parameter for addressing and managing flood hazards and should be used in hazard zone plans and spatial planning.

scholarly journals Calculation of the total cross-sectional area of the spool air of the distributor of an automobile air motor

2019 ◽  
Keyword(s):  
Distribution System ◽  
Combustion Engine ◽  
Slide Valve ◽  
Compressed Air ◽  
Entry And Exit ◽  
Flow Area ◽  
Cross Sectional ◽  
Software Application ◽  
Analytical Estimation ◽  
Separate Block

One of actual issues in the field of gas dynamics of piston engines which concerns the analytical estimation of influence of structural and regime parameters on the processes of flowing of gases through gas distribution mechanisms is examined. Gas interchange process in two-tact engines is performed by means of opening-closing of blow-off windows or slide-valve with a piston. The method of calculating the total plane of the flow area of slide-valve air distributor for a motor-car pneumatic engine is proposed. The mathematical descriptions of the pre-set areas of the entry and exit openings of slide-valve air distributor have been performed with the help of the theory of R-functions. The algorithm for creating the computer calculating program for determining the flow area of slide-valve air distributor is considered. The proposed algorithm has been used for developing the software application intended for calculating the areas which are formed by the entry and exit openings of slide-valve accounting for their different possible configurations. The calculations of flow area of these openings allow determining the air losses in the air distributive system of pneumatic engine and defining the specific size for the inlets and outlets of the compressed air. The results of calculations of the air distribution system and the parameters of the compressed air intake is presented as a separate block in the general dynamic model of calculations of working processes of the motor-car pneumatic engine, when determining the speed, temperature and air flow of the slide-valve air distributor. The motor-car pneumatic engine is more economical and environmentally friendly in comparison with the internal combustion engine at the low revolutions.

scholarly journals Widefield Swept-Source Optical Coherence Tomography Angiography Assessment of Choroidal Changes in Vogt-Koyanagi-Harada Disease

2021 ◽  
Vol 8 ◽  
Author(s):  
Yujing Qian ◽  
Jingyuan Yang ◽  
Anyi Liang ◽  
Chan Zhao ◽  
Fei Gao ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Disease Activity ◽  
Optical Coherence Tomography Angiography ◽  
Comprehensive Evaluation ◽  
Cross Sectional Study ◽  
Optical Coherence ◽  
Flow Area ◽  
Cross Sectional ◽  
Swept Source ◽  
Vascular Abnormalities

Purpose: To investigate choroidal changes in patients with Vogt-Koyanagi-Harada disease (VKH) using widefield swept-source optical coherence tomography angiography (SS-OCTA).Methods: In this cross-sectional study, 133 eyes of 69 patients with VKH (52 eyes of 28 active VKH patients and 81 eyes of 41 inactive VKH patients) and 104 eyes of 52 age and sex matched healthy volunteers were imaged using a widefield SS-OCTA instrument. On 12 mm × 12 mm OCTA scans, mean choroidal thickness (MCT), choroidal vascularity index (CVI), choriocapillaris (CC) flow area, and mean retinal thickness (MRT) were separately calculated in the fovea (diameter of 1 mm) and in concentric rings with different radii (1–3, 3–6, 6–9, and 9–12 mm).Results: Eyes with active VKH showed significant increases in MCT, CVI, and MRT, and decreased CC flow area in all central and peripheral regions (0–1, 1–3, 3–6, 6–9, and 9–12 mm) than in the healthy eyes (p ≤ 0.01) and inactive VKH eyes (p < 0.05). Inactive VKH eyes only showed marked decrease in CC flow area in all regions compared with controls (p < 0.05). Flow voids were observed in 51 of 52 (98.1%) active VKH eyes and 50 of 81 (61.7%) inactive VKH eyes on 12 mm × 12 mm OCTA. The MCT of all regions was significantly correlated with age, disease duration, and disease activity, whereas CVI was associated with age and disease activity. The CC flow void was related to visual acuity in all regions (p < 0.05).Conclusion: Widefield SS-OCTA enables a more comprehensive evaluation of chorioretinal changes in patients with VKH disease. Structural and vascular abnormalities are observed in both the central and peripheral choroid and are closely correlated with disease activity.

scholarly journals The Study on Internal Flow Characteristics of Disc Filter under Different Working Condition

2021 ◽  
Vol 11 (16) ◽  
pp. 7715
Author(s):  
Yanbing Chi ◽  
Peiling Yang ◽  
Zixuan Ma ◽  
Haiying Wang ◽  
Yuxuan Liu ◽  
...  
Keyword(s):  
Irrigation System ◽  
Flow Characteristics ◽  
Head Loss ◽  
Main Flow ◽  
Horizontal Direction ◽  
Macroscopic Model ◽  
Hydraulic Characteristics ◽  
Flow Area ◽  
Micro Irrigation ◽  
Filter Bed

A disc filter (DF) is an important component in a micro irrigation system. However, it has a high head loss and low filtration efficiency, which can lead to the inoperability of micro irrigation systems. To improve the filtration ability and to decrease the pressure loss of the irrigation system, it is necessary to internalize the hydraulic characteristics of DFs. In this study, the filter bed of a DF was divided into three parts, i.e., upper, middle, and lower, which were wrapped with a transparent film. The wrapped part was completely blocked. The purpose was to analyze the hydraulic characteristics of different clogged conditions in three types of filters under four types of flows. In addition, we attempted to simulate the filter operation process with computational fluid dynamics, based on two aspects—a macroscopic model and a simplified model. The results showed that the patterns of head loss among all of the DFs was consistent, and the macroscopic model that treated filter bed as a porous medium could express the measured results. The macroscopic models observed that there was a circular flow in the DF, and the flow velocity presented a symmetrical distribution in a horizontal direction. The middle of the filter element appeared in a high-pressure area and demonstrated the highest head loss, which may be the main flow area of the DF, and the inner flow characteristics of the DF were consistent under different conditions. The simplified models showed that the main flow area is near the filter bed in the inner DF, and the flow is tangent to the filter bed between 45 and 90 degrees in a horizontal direction. The uneven distribution of velocity and pressure on the filter bed might be necessary factors to impact filter efficiency.

Evaluation of the reasons for the microvascular changes in patients with Fabry disease using optic coherence tomography angiography

2020 ◽  
pp. 112067212097428
Author(s):  
Cezmi Dogan ◽  
Busenur Gonen ◽  
Mevlut Tamer Dincer ◽  
Burak Mergen ◽  
Ertugrul Kiykim ◽  
...  
Keyword(s):  
Blood Flow ◽  
Fabry Disease ◽  
Renal Involvement ◽  
Vascular Density ◽  
Optic Coherence Tomography ◽  
Healthy Controls ◽  
Duration Of Treatment ◽  
Flow Area ◽  
Cross Sectional ◽  
Significant Difference

Purpose: To investigate the blood flow changes in the choriocapillaris and the superficial and deep capillary plexus of the retina using optic coherence tomography angiography (OCTA) in patients with Fabry disease (FD) and reveal any possible association of these changes with the systemic findings. Methods: This cross-sectional study included 38 patients with FD and age- and gender-matched 40 healthy controls. OCTA images were obtained from all patients. Superficial (sCVD) and deep capillary vascular density (dCVD) in the foveal, parafoveal, and perifoveal zones and the whole image were recorded for each patient. Flow area in the choriocapillaris and central macular thickness (CMT) were also recorded. Results: Patients with FD showed a lower whole image (54.45 ± 5.99% vs 57.32 ± 6.71%, p = 0.004), foveal (34.94 ± 7.60% vs 39.65 ± 7.03%, p = 0.003), parafoveal (57.41 ± 4.85% vs 59.19 ± 4.67%, p = 0.043), and perifoveal (55.87 ± 6.43% vs 58.87 ± 7.02%, p = 0.003) dCVD compared to the healthy controls without a significant difference in the sCVD and choriocapillaris blood flow ( p > 0.05). A significantly lower whole image and foveal dCVD in the FD patients with renal involvement was observed compared to the healthy controls ( p = 0.027 and p = 0.024, respectively) without any significant difference between the FD patients without renal involvement and healthy controls ( p = 0.17 and p = 0.13, respectively). CMT was significantly higher in FD patients with renal involvement compared to the ones without renal involvement (252.1 ± 18.5 µm vs 235.5 ± 17.6 µm, p = 0.016). Conclusion: Patients with FD showed a lower dCVD without any change in sCVD and choriocapillaris compared to the healthy controls. This decrease was associated mostly with the renal involvement and duration of treatment.

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