scholarly journals Effect of Error in SO2 Slant Column Density on the Accuracy of SO2 Transport Flow Rate Estimates Based on GEMS Synthetic Radiances

2021 ◽  
Vol 13 (15) ◽  
pp. 3047
Author(s):  
Junsung Park ◽  
Wonei Choi ◽  
Hyung-Min Lee ◽  
Rokjin J. Park ◽  
Seong-Yeon Kim ◽  
...  
Keyword(s):  
Flow Rate ◽  
Column Density ◽  
Wind Data ◽  
Long Range Transport ◽  
Environment Monitoring ◽  
Vertical Column ◽  
Flow Rates ◽  
Range Transport ◽  
The Mean ◽  
Transport Flow

This study investigates the uncertainties associated with estimates of the long-range transport SO2 (LRT-SO2) flow rate calculated hourly using Geostationary Environment Monitoring Spectrometer (GEMS) synthetic radiances. These radiances were simulated over the Korean Peninsula and the surrounding regions using inputs from the GEOS-Chem model for January, April, July, and October 2016. The LRT-SO2 calculation method, which requires SO2 vertical column densities, wind data, and planetary boundary layer information, was used to quantify the effects of the SO2 slant column density (SCD) retrieval error and uncertainties in wind data on the accuracy of the LRT-SO2 estimates. The effects were estimated for simulations of three anthropogenic and three volcanic SO2 transport events. When there were no errors in the GEMS SO2 SCD and wind data, the average true LRT-SO2 flow rates (standard deviation) and those calculated for these events were 1.17 (± 0.44) and 1.21 (±0.44) Mg/h, respectively. However, the averages of the true LRT-SO2 flow rates and those calculated for the three anthropogenic (volcanic) SO2 events were 0.61 (1.17) and 0.64 (1.20) Mg/h, respectively, in the presence of GEMS SO2 SCD errors. In the presence of both errors in the GEMS SO2 SCD and wind data, the averages of the true LRT-SO2 flow rates and those calculated for the three anthropogenic (volcanic) SO2 events were 0.61 (1.17) and 0.61 (1.04) Mg/h, respectively. This corresponds to differences of 2.1% to 23.1% between the simulated and true mean LRT-SO2 flow rates. The mean correlation coefficient (R), intercept, and slope between the true and simulated LRT-SO2 flow rates were 0.51, 0.43, and 0.45 for the six simulated events, respectively. This study demonstrates that SO2 SCD accuracy is an important factor in improving estimates of LRT-SO2 flow rates.

Renal Function in Unanaesthetized River Lampreys (Lampetra FluviatilisL.): Effects of Anaesthesia, Temperature and Environmental Salinity

1983 ◽  
Vol 105 (1) ◽  
pp. 351-362 ◽  
Author(s):  
A. J. MCVICAR ◽  
J. C. RANKIN
Keyword(s):  
Renal Function ◽  
Flow Rate ◽  
Ventilation Rate ◽  
Urine Flow ◽  
The Body ◽  
Urine Flow Rate ◽  
Flow Rates ◽  
Gill Ventilation ◽  
Daily Excretion ◽  
The Mean

1. Improved estimates of urine flow rates of lampreys in various salinities were obtained by the collection of urine for periods of up to 48 h from minimally-stressed, unanaesthetized fish, following catheterization of the urinogenital papilla. 2. The mean urine flow rate of freshwater lampreys was 200.7 ±14.3 ml kg−1 day−1. 3. Urine flow in freshwater lampreys was correlated with spontaneous changes in gill ventilation rate. MS222 anaesthesia reduced both ventilation and urine flow rates, but pronounced effects were only observed at concentrations greater than those needed to induce light anaesthesia (50–55 mg 1−1). Urine flow rate in unanaesthetized fish was extremely sensitive to rapid (6°Ch−1) changes in temperature and Q10 (6–16°C) was approximately 5. 4. Urine flow rate decreased rapidly as the osmotic difference between the body fluids and environment approached zero, and the rate of flow in 30% seawater lampreys was only 7.6% that of freshwater fish. 5. There was no evidence for an effect of environmental calcium concentration on branchial osmotic permeability. 6. Extensive tubular reabsorption of ions occurred in freshwater lampreys. The total daily excretion rate of sodium ions generally decreased in salinities hyperosmotic to the plasma, indicating enhanced reabsorption, but secretion of magnesium and sulphate ions was greatly increased. Urine osmolarity was significantly increased in lampreys in hyperosmotic salinities. 7. Present data compare favourably with data obtained previously from anaesthetized animals, indicating that renal function in lampreys is not significantly impaired by light MS222 anaesthesia.

Fluid Dynamics of Tubes Used in Membrane-Tube Type Glaucoma Shunt Devices

2019 ◽  
Author(s):  
Jong Chul Han ◽  
Young Hoon Hwang ◽  
Byung Heon Ahn
Keyword(s):  
Flow Rate ◽  
Venous Pressure ◽  
Pressure Control ◽  
Full Length ◽  
Internal Diameter ◽  
Minimal Risk ◽  
Flow Rates ◽  
Membrane Tube ◽  
The Mean ◽  
Half Length

Abstract Purpose: To investigate the outflow characteristics of silicone tubes with intraluminal stents used in membrane-tube (MT) type glaucoma shunt devices (MT-device). Methods: The silicone tubes used in MicroMT (internal diameter of 100 µm with 7-0 nylon intraluminal stent) and Finetube MT (internal diameter of 200 µm with 5-0 nylon intraluminal stent) were connected to a syringe-pump that delivered a continuous flow of distilled water at flow rates of 2, 5, 10, and 25 µl/min. The pressures and resistances of tubes were measured at a steady flow rate with full-length, half-length, and absence of intraluminal stents. Results: At flow rates between 2 and 25 µl/min, the mean outflow resistance of tubes ranged from 3.0 ± 1.9 to 3.8 ± 1.7 mmHg/µl/min with a full-length intraluminal stent, 1.8 ± 1.1 to 2.2 ± 1.1 mmHg/µl/min with a half-length intraluminal stent, and 0.1 ± 0 to 0.2 ± 0 mmHg/µl/min without an intraluminal stent. At a physiologic state with a flow rate of 2 µl/min and episcleral venous pressure of 6 mmHg, the mean pressures of tubes were expected to be 13.2 ± 3.0, 10.5 ± 2.4, and 6.4 ± 0.2 mmHg in MicroMT with full-length, half-length, and absence of intraluminal stents, respectively, and 12.5 ± 3.9, 9.6 ± 2.4, and 6.2 ± 0.2 mmHg in Finetube MT with full-length, half-length, and absence of intraluminal stents, respectively. Variance of the pressure decreased according to the intraluminal stent retraction (P < 0.01). Conclusion: The tubes with intraluminal stents used in the MT-device showed safe (with a minimal risk of postoperative ocular hypotony) and effective (sufficient for intraocular pressure control) outflow characteristics.

Velocity and size characteristics of liquid-fuelled flames stabilized by a swirl burner

1990 ◽  
Vol 428 (1874) ◽  
pp. 129-155 ◽  
Keyword(s):  
Flow Rate ◽  
Elevated Temperatures ◽  
Outer Part ◽  
Arithmetic Mean ◽  
Recirculation Region ◽  
Reacting Flow ◽  
Air Velocity ◽  
Flow Rates ◽  
The Mean ◽  
Air Motion

Velocity and droplet size characteristics of an unconfined quarl burner, of 16 mm quarl inlet diameter, have been measured with a phase-Doppler anemometer at a swirl number of about 0.29: the Reynolds number of the flow was 30000, based on the cold bulk velocity of 30.4 m s -1 and the hydraulic diameter. The atomization was achieved by shear between the swirling air and six radial kerosene jets and the resulting Sauter and arithmetic mean diameters were about 70 and 50 μm respectively after injection: velocity characteristics are presented for three 5 μm-wide size classes, 10, 30 and 60 μm. The flows correspond to no combustion and combustion of natural gas with a heat release of 8 kW supplemented by liquid kerosene flow rates sufficient to generate 21.6 and 37.2 kW : the gas equivalence ratio was 0.45 and atomized kerosene at two flow rates increased the overall ratios to 1.64 and 2.53. In non­-reacting flow, droplets 30 μm and smaller are sufficiently small to be entrained by the mean air velocity towards the central part of the flow and into the swirl-induced recirculating air bubble. The 60 μm droplets are able to travel through the bubble uninfluenced by turbulent fluctuations in the air and are ‘centrifuged’ away from the centreline, through acquisition of a mean swirl velocity component, so that a large proportion of the kerosene volume flow rate lies at the edge of the swirling jet. Because larger droplets are centrifuged to the outer part of the flow, whereas the smaller are entrained towards the centreline, the Sauter and arithmetic mean diameters are, by 1.22 quarl exit diameters downstream of the quarl, approximately 65 and 36 μm at the outer part of the flow and 35 and 12 μm near the centreline in the inert flow. In reacting flow, droplets evaporate rapidly in regions of elevated temperatures and hence no droplets are found within the flame brush and recirculation region. The aerodynamic response of each size class to the air velocity is similar to inert flow so that the majority of the kerosene flow is centrifuged away from the flame. On exit from the quarl, the evaporation and burning rates cause the Sauter and arithmetic mean diameters to be about 70 and 50 μm and 60 and 30 μm at the inner and outer edges of the spray respectively. By 1.22 quarl exit-diameters from the exit of the quarl, the air motion entrains droplets smaller than about 30 μm towards the flame, at the inner edge of the spray, so that the Sauter and arithmetic mean diameters are 60 and 40 μm at the outer edge of the jet. There is comparatively little effect of changing the flow rate of kerosene because the combustion is controlled by the low available number of smaller droplets, although the Group combustion number corresponds to ‘cloud’ burning. The relative response of droplets to the mean and turbulent components of air motion, including the ‘centrifuging’ effect, can be scaled to other flows through dimensionless numbers defined in the text.

Mechanics of machine milking: II. The flow-rate pattern within single pulsation cycles

1966 ◽  
Vol 33 (2) ◽  
pp. 177-191 ◽  
Author(s):  
C. C. Thiel ◽  
P. A. Clough ◽  
D. R. Westgarth ◽  
D. N. Akam
Keyword(s):  
Flow Rate ◽  
Response Rate ◽  
Sphincter Muscle ◽  
Mean Flow ◽  
Considerable Time ◽  
Flow Rates ◽  
Machine Milking ◽  
Closing Force ◽  
The Mean ◽  
Pulsation Cycle

SummaryThe milk flowing during a single pulsation cycle was collected in a circle of contiguous cups which rotated in a chamber at 1 rev/pulsation cycle just below the end of the teatcup liner. The mean flow rate during the time taken for each collecting cup to pass under the milk stream was calculated and the flow-rate curve for the milkflow period of the pulsation cycle plotted. Flow rates were measured at 130, 97, 65, 32 and 16 c/min, and also after the pulsator had been stopped with the liner open for 0·5 min (0 pulsation).It was concluded from the series of flow-rate curves at the different pulsation rates that flow rate from the teat increased in about 0·05 sec to a steady value which continued for 0·5 sec or so, and then declined over a period of about 1·5 sec to a new constant value approximately equal to that shown after milk had flowed continuously from the teat for 0·5 min.These results suggest that once the pressure difference across the streak canal during milking forces the teat sphincter open a considerable time elapses before the muscle control system responds, and that a further much longer period elapses before the full closing force of the sphincter is exerted. Thus, it would appear that at pulsation rates of about 50 c/min and above, the streak canal is closed by pressure exerted on the teat by the closing liner, the sphincter muscle playing no active part because its response rate is slow compared with the pulsation rate. At lower pulsation rates the flow rate declines during each cycle because the sphincter muscle has time to exert a closing force to a greater or lesser extent depending on the duration of the milkflow period.

scholarly journals On the origin of the occasional spring nitrate peak in Greenland snow

2014 ◽  
Vol 14 (24) ◽  
pp. 13361-13376 ◽  
Author(s):  
L. Geng ◽  
J. Cole-Dai ◽  
B. Alexander ◽  
J. Erbland ◽  
J. Savarino ◽  
...  
Keyword(s):  
Long Range ◽  
Column Density ◽  
Nitrate Concentration ◽  
Ice Core ◽  
The Arctic ◽  
Long Range Transport ◽  
Pollution Transport ◽  
Spring Peak ◽  
Nitrate Production ◽  
Range Transport

Abstract. Ice core nitrate concentrations peak in the summer in both Greenland and Antarctica. Two nitrate concentration peaks in one annual layer have been observed some years in ice cores in Greenland from samples dating post-1900, with the additional nitrate peak occurring in the spring. The origin of the spring nitrate peak was hypothesized to be pollution transport from the mid-latitudes in the industrial era. We performed a case study on the origin of a spring nitrate peak in 2005 measured from a snowpit at Summit, Greenland, covering 3 years of snow accumulation. The effect of long-range transport of nitrate on this spring peak was excluded by using sulfate as a pollution tracer. The isotopic composition of nitrate (δ15N, δ18O and Δ17O) combined with photochemical calculations suggest that the occurrence of this spring peak is linked to a significantly weakened stratospheric ozone (O3) layer. The weakened O3 layer resulted in elevated UVB (ultraviolet-B) radiation on the snow surface, where the production of OH and NOx from the photolysis of their precursors was enhanced. Elevated NOx and OH concentrations resulted in enhanced nitrate production mainly through the NO2 + OH formation pathway, as indicated by decreases in δ18O and Δ17O of nitrate associated with the spring peak. We further examined the nitrate concentration record from a shallow ice core covering the period from 1772 to 2006 and found 19 years with double nitrate peaks after the 1950s. Out of these 19 years, 14 of the secondary nitrate peaks were accompanied by sulfate peaks, suggesting long-range transport of nitrate as their source. In the other 5 years, low springtime O3 column density was observed, suggesting enhanced local production of nitrate as their source. The results suggest that, in addition to direct transport of nitrate from polluted regions, enhanced local photochemistry can also lead to a spring nitrate peak. The enhanced local photochemistry is probably associated with the interannual variability of O3 column density in the Arctic, which leads to elevated surface UV radiation in some years. In this scenario, enhanced photochemistry caused increased local nitrate production under the condition of elevated local NOx abundance in the industrial era.

Importance of inspiratory flow rate in the cough response to citric acid inhalation in normal subjects

1990 ◽  
Vol 78 (5) ◽  
pp. 521-525 ◽  
Author(s):  
Manuel J. Barros ◽  
Stefano J. Zammattio ◽  
P. John Rees
Keyword(s):  
Citric Acid ◽  
Flow Rate ◽  
Geometric Mean ◽  
Normal Subjects ◽  
Forced Expiratory Volume ◽  
Inspiratory Flow ◽  
Inspiratory Flow Rate ◽  
Flow Rates ◽  
Cough Response ◽  
The Mean

1. The cough response to inhalation of citric acid is produced mainly by irritation of the larynx and trachea. Variations in the inspiratory flow rate might lead to changes in deposition of the drug, and consequently in the cough threshold. 2. We have studied the effect of three different inspiratory flow rates in 11 normal, non-smoking subjects (nine males, aged 23–39 years), who inhaled nebulized citric acid (2.5–640 mg/l). The test finished when a cough. was produced at each inhalation (cough threshold) or the maximum concentration was reached. 3. The inspiratory flow rate was limited with a fixed resistance and displayed on a screen so that the subjects could reach a constant inspiratory flow rate of 50, 100 and 150 l/min with a submaximal inspiratory effort. 4. The mean (sd) inspiratory flow rates achieved were 51.4 (5.3), 86.2 (16.6) and 134.4 (22.9) l/min. Baseline forced expiratory volume in 1 s and functional vital capacity were not different on the 3 study days. 5. The cough threshold (geometric mean and 95% confidence intervals) was 21 (9–54) mg/l at an inspiratory flow rate of 50 l/min and 43 (13–141) mg/l at 150 l/min (P <0.05). The amount of drug tolerated by the subjects before the cough threshold was achieved was 5.2 (2.0–13.8) mg at an inspiratory flow rate of 50 l/min and 11.6 (3.4–39.8) mg at 150 l/min (P <0.05). The number of coughs per inhalation was 1.6 (1.1–2.0) at an inspiratory flow rate of 50 l/min and 1.1 (0.7–1.5) at 150 l/min (P <0.05). 6. We conclude that lower inspiratory flow rates were associated with a greater cough stimulus in the citric acid challenge procedure used in this study. This may be related to increased laryngeal deposition. The inspiratory flow rate is a variable which should be controlled in the performance of cough challenges with citric acid.

Studies on Fluoride Concentrations in Human Submandibular/Sublingual Saliva and their Relation to Flow Rate and Plasma Fluoride Levels

1989 ◽  
Vol 68 (2) ◽  
pp. 146-149 ◽  
Author(s):  
A. Oliveby ◽  
F. Lagerlof ◽  
J. Ekstrand ◽  
C. Dawes
Keyword(s):  
Flow Rate ◽  
Salivary Flow ◽  
Salivary Flow Rate ◽  
Flow Rates ◽  
Impression Material ◽  
Collection Device ◽  
Unstimulated Saliva ◽  
The Mean ◽  
Gustatory Stimulation ◽  
Highly Correlated

Submandibular/sublingual saliva and blood were collected from five subjects after ingestion of 1 mg fluoride as NaF. An individual collection device, made from a silicone impression material, was used to collect the saliva in 10-minute samples, before and during 2 hr after the fluoride intake. In two separate experiments on each individual, submandibular/sublingual saliva was collected continuously at different flow rates: without stimulation and with gustatory stimulation. Blood was also collected at intervals throughout the experiments. The concentration of fluoride in the submandibularlsublingual saliva was less than that in the plasma but independent of salivary flow rate. The ratio between the saliva and plasma fluoride concentrations at the peak of the mean plasma fluoride concentrations was 0.55 ± 0.13 and 0.69 ± 0.11 in the experiments on unstimulated and stimulated salivary flow rate, respectively. The total amount of the ingested fluoride dose that was excreted through the submandibular/sublingual glands during 130 min was highly correlated with the salivary flow rate. The fraction of the ingested fluoride dose excreted in 2 hr was 0.04 ± 0.02% in the unstimulated saliva and 0.15 ± 0.09% in the stimulated saliva.

Effect of Low Reynolds Number Mixed Convection on Channel Flows Structure

2012 ◽  
Author(s):  
Ahmed Elatar ◽  
Kamran Siddiqui
Keyword(s):  
Reynolds Number ◽  
Flow Rate ◽  
Wall Temperature ◽  
Heated Wall ◽  
Mean Velocity ◽  
Number Range ◽  
Flow Rates ◽  
Wall Heating ◽  
The Mean ◽  
Low Reynolds

The effect of wall heating on low Reynolds numbers channel flow has been investigated experimentally. The experiments were conducted at heated bottom wall temperatures from 30 °C to 50 °C for two flow rates 0.0210 and 0.0525 kg/s, corresponding to the Reynolds number range of 150 and 750 (in the absence of heating). The results showed that the initially laminar flow became turbulent due to wall heating, and that wall heating has a significant influence on both the mean and turbulent velocity fields. The mean velocity profiles were altered by the convective currents. The magnitude of mean streamwise velocity near the heated wall increased with an increase in the wall temperature. A back flow near the upper channel wall was also observed primarily at the lower flow rate which diminished for the high flow rate. The magnitude of backflow increased with an increase in the wall temperature. The turbulent intensities were found to increase with an increase in the wall temperature for both flow rates. The result also showed the presence of strong vortices originating from the heated wall and advecting towards the central core of the channel.

Novel external stenting for reconstruction of high flow arteriovenous fistula

2021 ◽  
pp. 112972982110155
Author(s):  
Vladimir Matoussevitch ◽  
Egan Kalmykov ◽  
Robert Shahverdyan
Keyword(s):  
Flow Rate ◽  
Cardiac Remodeling ◽  
Primary Patency ◽  
High Flow ◽  
Cobalt Chromium ◽  
Mean Flow ◽  
Flow Rates ◽  
Vein Segment ◽  
The Mean

Background: High-flow arteriovenous fistulae (HF-AVF) may lead to adverse cardiac remodeling in hemodialysis patients. We have investigated whether a novel external stent is safe and effective in reducing and stabilizing flow rates during a 1-year follow-up after HF-AVF reconstruction. Methods: All patients with HF-AVF (access flow rate ⩾ 1500 ml/min), who underwent HF-AVF reconstruction with external stenting in two centers between June 2018 and May 2020, were included in this retrospective analysis. During HF-AVF reconstruction, the dilated vein segment was resected, underwent volume reduction, and was externally stabilized using a braided cobalt-chromium external stent. AVF flow rates were assessed preoperatively, intraoperatively, and at follow up visits using duplex ultrasound. Results: Forty-three HF-AVFs in 42 patients were reconstructed and supported with an external stent (mean age 49 years, range 20–86 years; 74% men). Fifty-one percent were forearm AVFs, 49% were upper arm. The mean preoperative flow rate was 2622 ± 893 ml/min (range: 1500–6000 ml/min) and was decreased to 710 ± 221 ml/min (range: 300–1300 ml/min) intra-operatively after HF-AVF reconstruction. At 6 and 12-months follow-up, the mean flow rates were 1132 ± 320 ml/min (range: 470–1700 ml/min) and 1453 ± 888 ml/min (range: 300–3800 ml/min), respectively. Recurrence of high flow (>1500 ml/min) occurred in 16% and 25% of the patients at 6 and 12 months and primary patency rates were 86% and 70%, respectively. Conclusions: This early experience with novel external stenting for HF-AVF reconstruction demonstrates that it is a safe and effective method for reducing and stabilizing flow rates up to 1-year post procedure. Additional studies are required to evaluate the durability of this procedure over the longer term and assess its effect on cardiac remodeling.

scholarly journals Ex VivoCharacterization of Effects of Renal Replacement Therapy Modalities and Settings on Pharmacokinetics of Meropenem and Vaborbactam

2018 ◽  
Vol 62 (10) ◽  
Author(s):  
Fekade B. Sime ◽  
Saurabh Pandey ◽  
Nermin Karamujic ◽  
Suzanne Parker ◽  
Elizabeth Alexander ◽  
...  
Keyword(s):  
Renal Replacement Therapy ◽  
Replacement Therapy ◽  
Surface Area ◽  
Flow Rate ◽  
Ex Vivo ◽  
Flow Rates ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Effluent Flow Rate ◽  
The Mean

ABSTRACTThe combination product meropenem-vaborbactam, with activity against KPC-producing carbapenem-resistantEnterobacteriaceae, is likely to be used during renal replacement therapy. The aim of this work was to describe the extracorporeal removal (adsorption and clearance) of meropenem-vaborbactam during continuous venovenous hemofiltration (CVVH). Anex vivomodel was used to examine the effects of a matrix of operational settings. Vaborbactam did not adsorb to AN69 (acrylonitrile and sodium methallylsulfonate copolymer) ST100 (surface area, 1 m2) hemofilter; the mean (±standard deviation [SD]) meropenem adsorption was 9% (±1%). The sieving coefficients (mean ± SD) with AN69 ST100 and ST150 (surface area, 1.5 m2) filters ranged from 0.97 ± 0.16 to 1.14 ± 0.12 and from 1.13 ± 0.01 to 1.53 ± 0.28, respectively, for meropenem and from 0.64 ± 0.39 to 0.90 ± 0.14 and 0.78 ± 0.18 to 1.04 ± 0.28, respectively, for vaborbactam. At identical settings, vaborbactam sieving coefficients were 25% to 30% lower than for meropenem. Points of dilution, blood flow rates, or effluent flow rates did not affect sieving coefficients for either drug. However, doubling the effluent flow rate resulted in >50 to 100% increases in filter clearance for both drugs. Postfilter dilution resulted in 40 to 80% increases in filter clearance at a high effluent flow rate (4,000 ml/h), compared with ∼15% increases at a low effluent flow rate (1,000 ml/h) for both drugs. For all combinations of setting and filters tested, vaborbactam clearance was lower than that of meropenem by ∼20 to 40%. Overall, meropenem-vaborbactam is efficiently cleared in CVVH mode.

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