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Sample records for high flow rate

  1. Performance of high flow rate samplers for respirable particle collection.

    Science.gov (United States)

    Lee, Taekhee; Kim, Seung Won; Chisholm, William P; Slaven, James; Harper, Martin

    2010-08-01

    The American Conference of Governmental Industrial hygienists (ACGIH) lowered the threshold limit value (TLV) for respirable crystalline silica (RCS) exposure from 0.05 to 0.025 mg m(-3) in 2006. For a working environment with an airborne dust concentration near this lowered TLV, the sample collected with current standard respirable aerosol samplers might not provide enough RCS for quantitative analysis. Adopting high flow rate sampling devices for respirable dust containing silica may provide a sufficient amount of RCS to be above the limit of quantification even for samples collected for less than full shift. The performances of three high flow rate respirable samplers (CIP10-R, GK2.69, and FSP10) have been evaluated in this study. Eleven different sizes of monodisperse aerosols of ammonium fluorescein were generated with a vibrating orifice aerosol generator in a calm air chamber in order to determine the sampling efficiency of each sampler. Aluminum oxide particles generated by a fluidized bed aerosol generator were used to test (i) the uniformity of a modified calm air chamber, (ii) the effect of loading on the sampling efficiency, and (iii) the performance of dust collection compared to lower flow rate cyclones in common use in the USA (10-mm nylon and Higgins-Dewell cyclones). The coefficient of variation for eight simultaneous samples in the modified calm air chamber ranged from 1.9 to 6.1% for triplicate measures of three different aerosols. The 50% cutoff size ((50)d(ae)) of the high flow rate samplers operated at the flow rates recommended by manufacturers were determined as 4.7, 4.1, and 4.8 microm for CIP10-R, GK2.69, and FSP10, respectively. The mass concentration ratio of the high flow rate samplers to the low flow rate cyclones decreased with decreasing mass median aerodynamic diameter (MMAD) and high flow rate samplers collected more dust than low flow rate samplers by a range of 2-11 times based on gravimetric analysis. Dust loading inside the

  2. High Frame Rate Synthetic Aperture 3D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Holbek, Simon; Stuart, Matthias Bo

    2016-01-01

    , current volumetric ultrasonic flow methods are limited to one velocity component or restricted to a reduced field of view (FOV), e.g. fixed imaging planes, in exchange for higher temporal resolutions. To solve these problems, a previously proposed accurate 2-D high frame rate vector flow imaging (VFI...

  3. High flow rate microsieve for bio medical applications

    NARCIS (Netherlands)

    van Rijn, C.J.M.; Nijdam, W.; Elwenspoek, Michael Curt

    1995-01-01

    A new composite filtration membrane having a thin filtration or sieving layer has been developed. This filtration membrane with a high pore density and a narrow pore size distribution on a macro porous support shows good separation behaviour and a high flow rate. Because of the construction method,

  4. Taylor dispersion analysis in coiled capillaries at high flow rates.

    Science.gov (United States)

    Lewandrowska, Anna; Majcher, Aldona; Ochab-Marcinek, Anna; Tabaka, Marcin; Hołyst, Robert

    2013-04-16

    Taylor Dispersion Analysis (TDA) has been performed for analytes moving at high flow rates in long, coiled capillaries. A thin injection zone of the analyte is stretched by the flow and final distribution of concentration of the analyte at the end of the capillary has the gaussian shape. The high flow rates in coiled capillary generate vortices. They convectively mix the analyte across the capillary. This mixing reduces the width of the gaussian distribution several times in comparison to the width obtained in a straight capillary in standard TDA. We have determined an empirical, scaling equation for the width as a function of the flow rate, molecular diffusion coefficient of the analyte, viscosity of the carrier phase, internal radius of the cylindrical capillary, and external radius of the coiled capillary. This equation can be used for different sizes of capillaries in a wide range of parameters without an additional calibration procedure. Our experimental results of flow in the coiled capillary could not be explained by current models based on approximate solutions of the Navier-Stokes equation. We applied the technique to determine the diffusion coefficients of the following analytes: salts, drugs, single amino acids, peptides (from dipeptides to hexapeptides), and proteins.

  5. Adiabatic flow curves of metallic materials at high strain rates

    Energy Technology Data Exchange (ETDEWEB)

    El-Magd, E. [Technische Hochschule Aachen (Germany); Scholles, H. [Rheinmetall Industrie GmbH, Unterluess (Germany); Weisshaupt, H. [Rheinmetall Industrie GmbH, Unterluess (Germany)

    1996-08-01

    Dynamic compression tests are carried out on Armco iron, Cr-V-steel, Ni-Cr-Mo-V-steel, an austenitic Ni-Cr-Mo-steel, tantalum, nickel and Ni{sub 3}Al and magnesium. The flow curves are analysed to determine the influence of the deformation energy which is transformed into heat on the flow behaviour and mechanical stability. Not only the material properties but also the conditions of friction between the specimen and the compresion tool are found to have a greate influence on the flow stress reduction and stability. High frictional forces promote mechanical instability of materials with low strain hardening and low strain rate sensitivity. (orig.) [Deutsch] Schlagdruckversuche werden an Armcoeisen, CrV-Stahl, NiCr-MoV-Stahl, austenitischen NiCrMo-Stahl, Tantal, Nickel, Ni{sub 3}Al und Magnesium durchgefuehrt. Die ermittelten Fliesskurven werden analysiert, um den Einfluss der in Waerme umgewandelte Verformungsarbeit auf das Fliessverhalten und die mechanische Stabilitaet zu erfassen. Nicht nur die Werkstoffeigenschaften sondern auch die Reibungsbedingungen erweisen sich als massgebliche Einflussgroessen fuer Fliessspannungsabnahme und die Stabilitaet. Hohe Reibungskraefte foerdern die Verformungslokalisierung und die mechanische Instabilitaet von Werkstoffen mit niedriger Verfestigung und niedriger Geschwindigkeitsempfindlichkeit. (orig.)

  6. High flow rates during modified ultrafiltration decrease cerebral blood flow velocity and venous oxygen saturation in infants.

    Science.gov (United States)

    Rodriguez, Rosendo A; Ruel, Marc; Broecker, Lothar; Cornel, Garry

    2005-07-01

    The intracranial hemodynamic effects of modified ultrafiltration in children are unknown. We investigated the effects of different blood flow rates during modified ultrafiltration on the cerebral hemodynamics of children with weights above and below 10 kg. Thirty-one children (weights: 10 kg, n = 10) undergoing cardiopulmonary bypass were studied. Middle-cerebral artery blood flow velocities and cerebral mixed venous oxygen saturations were measured before, five minutes from the beginning, and at the end of ultrafiltration. Patients were classified according to their blood flow rates during ultrafiltration in three groups: high (> or = 20 mL/kg/min), moderate (10-19 mL/kg/min), and low flow rates (flow rates of ultrafiltration and the decline in mean cerebral blood flow velocity (r = - 0.48; p = 0.005) and cerebral oxygen saturation (r = - 0.49; p = 0.005) or hematocrit increase (r = 0.59; p = 0.001). Infants exposed to high flow rates had greater reduction of cerebral blood flow velocity and regional mixed venous saturation and higher hematocrit at the end of ultrafiltration compared with those subjected to moderate and low flow rates (p flow rates through the ultrafilter during modified ultrafiltration transiently decrease the cerebral circulation in young infants compared with lower blood flow rates. These effects may be related to an increased diastolic runoff from the aorta into the ultrafiltration circuit that leads to a "stealing" effect from the intracranial circulation, which may be important in infants with dysfunctional cerebral autoregulation.

  7. A high rate flow-focusing foam generator

    OpenAIRE

    Lorenceau, Elise; Sang, Yann Yip Cheung; Hohler, Reinhard; Cohen-Addad, Sylvie

    2006-01-01

    We use a rigid axisymetric microfluidic flow focusing device to produce monodisperse bubbles, dispersed in a surfactant solution. The gas volume fraction of the dispersion collected out of this device can be as large as 90%, demonstrating that foam with solid-like viscoelastic properties can be produced in this way. The polydispersity of the bubbles is so low that we observe crystallization of our foam. We measure the diameter of the bubbles and compare these data to recent theoretical predic...

  8. High Sensitivity Carbon Nanotubes Flow-Rate Sensors and Their Performance Improvement by Coating

    Directory of Open Access Journals (Sweden)

    Xing Yang

    2010-05-01

    Full Text Available A new type of hot-wire flow-rate sensor (HWFS with a sensing element made of a macro-sized carbon nanotube (CNT strand is presented in this study. An effective way to improve repeatability of the CNT flow-rate sensor by coating a layer of Al2O3 on the CNT surface is proposed. Experimental results show that due to the large surface-to-volume ratio and thin coated Al2O3 layer, the CNT flow-rate sensor has higher sensitivity and faster response than a conventional platinum (Pt HWFS. It is also demonstrated that the covered CNT flow-rate sensor has better repeatability than its bare counterpart due to insulation from the surrounding environment. The proposed CNT flow-rate sensor shows application potential for high-sensitivity measurement of flow rate.

  9. High Sensitivity Carbon Nanotubes Flow-Rate Sensors and Their Performance Improvement by Coating

    Science.gov (United States)

    Yang, Xing; Zhou, Zhaoying; Wang, Dingqu; Liu, Xiaoli

    2010-01-01

    A new type of hot-wire flow-rate sensor (HWFS) with a sensing element made of a macro-sized carbon nanotube (CNT) strand is presented in this study. An effective way to improve repeatability of the CNT flow-rate sensor by coating a layer of Al2O3 on the CNT surface is proposed. Experimental results show that due to the large surface-to-volume ratio and thin coated Al2O3 layer, the CNT flow-rate sensor has higher sensitivity and faster response than a conventional platinum (Pt) HWFS. It is also demonstrated that the covered CNT flow-rate sensor has better repeatability than its bare counterpart due to insulation from the surrounding environment. The proposed CNT flow-rate sensor shows application potential for high-sensitivity measurement of flow rate. PMID:22399913

  10. Computed Tomography Angiography With High Flow Rates: An In Vitro and In Vivo Feasibility Study.

    Science.gov (United States)

    Mihl, Casper; Kok, Madeleine; Wildberger, Joachim E; Turek, Jakub; Muehlenbruch, Georg; Das, Marco

    2015-07-01

    The aims of this study were to test high-flow application of contrast media (CM) using novel high-flow needles and to assess injection- and flow-related parameters in a circulation phantom and in an in vivo population. A circulation phantom simulating physiological parameters was used. Preheated CM (300 mg/mL) was injected at flow rates varying between 5 and 15 mL/s through a novel 18-gauge high-flow intravenous injection needle. In addition, feasibility of these high-flow needles was tested with administration of flow rates of 9 mL/s in 20 patients referred for pre-transcatheter aortic valve implantation assessment. Injection parameters (eg, peak pressures, peak flow rates) in both phantom and in vivo setup were continuously monitored by a data acquisition program. Attenuation at predefined levels of the aorta (eg, aortic root to common femoral arteries) was measured in all patients to determine clinical applicability. In the phantom setup, injection rates up to 15 mL/s were feasible. An enhancement plateau was reached at 11 mL/s (464 [20] HU). In patients, no pressure- or flow-related complications (eg, extravasation) were recorded (mean [SD] peak pressure, 154 [8] psi; mean [SD] peak flow rate, 9.2 [0.1 mL/s; range, 9.1-9.6]). Diagnostic attenuation values were reached at all predefined levels of the aorta (330.8 [113.1] HU to 622.9 [81.5] HU). These results indicate that injections with 9 mL/s using high-flow injection needles are safe. The pressure limit of 325 psi was not reached, and the injections resulted in diagnostic attenuation values. Using this dedicated needle, high flow rates should not be considered a drawback for CM application in routine CT angiography examinations.

  11. Quartz measurement in coal dust with high-flow rate samplers: laboratory study.

    Science.gov (United States)

    Lee, Taekhee; Lee, Eun Gyung; Kim, Seung Won; Chisholm, William P; Kashon, Michael; Harper, Martin

    2012-05-01

    A laboratory study was performed to measure quartz in coal dust using high-flow rate samplers (CIP10-R, GK2.69 cyclone, and FSP10 cyclone) and low-flow rate samplers [10-mm nylon and Higgins-Dewell type (BGI4L) cyclones] and to determine whether an increased mass collection from high-flow rate samplers would affect the subsequent quartz measurement by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analytical procedures. Two different sizes of coal dusts, mass median aerodynamic diameter 4.48 μm (Coal Dust A) and 2.33 μm (Coal Dust B), were aerosolized in a calm air chamber. The mass of coal dust collected by the samplers was measured gravimetrically, while the mass of quartz collected by the samplers was determined by FTIR (NIOSH Manual of Analytical Method 7603) and XRD (NIOSH Manual of Analytical Method 7500) after one of two different indirect preparations. Comparisons between high-flow rate samplers and low-flow rate samplers were made by calculating mass concentration ratios of coal dusts, net mass ratios of coal dusts, and quartz net mass. Mass concentrations of coal dust from the FSP10 cyclone were significantly higher than those from other samplers and mass concentrations of coal dust from 10-mm nylon cyclone were significantly lower than those from other samplers, while the CIP10-R, GK2.69, and BGI4L samplers did not show significant difference in the comparison of mass concentration of coal dusts. The BGI4L cyclone showed larger mass concentration of ∼9% compared to the 10-mm nylon cyclone. All cyclones provided dust mass concentrations that can be used in complying with the International Standard Organization standard for the determination of respirable dust concentration. The amount of coal dust collected from the high-flow rate samplers was found to be higher with a factor of 2-8 compared to the low-flow rate samplers but not in direct proportion of increased flow rates. The high-flow rate samplers collected more quartz compared to

  12. Flow rates of large animal fluid delivery systems used for high-volume crystalloid resuscitation.

    Science.gov (United States)

    Nolen-Walston, Rose D

    2012-12-01

    Large animal species in states of shock can require particularly high flow rates for volume resuscitation and the ability to deliver adequate volumes rapidly may be a rate-limiting step. The objective of this study was to determine the maximum flow rates of common combinations of IV catheter, extension set, and fluid administration sets. University veterinary teaching hospital. In vitro experimental study. Maximum flow rates were measured using combinations of 4 IV catheters (3 14-Ga and a single 10-Ga), 2 IV catheter extension sets (small bore and large bore), and 2 types of fluid administration sets (standard 2-lead large animal coiled IV set and nonpressurized 4-lead arthroscopic irrigation set). The catheter, extension sets, and administration sets were arranged in 16 configurations, and flow rates measured in triplicate using tap water flowing into an open receptacle. Flow rates ranged from 7.4 L/h with an over-the-wire 14-Ga catheter, small-bore extension, and coil set, to 51.2 L/h using a 10-Ga catheter, no extension, and arthroscopic irrigation set. There was an increase of 1.3-8.9% in flow rates between the large- versus small-bore extension sets. Crystalloid delivery in vivo to an adult horse was 21% slower (9.1 L/h versus 11.5 L/h) than the corresponding in vitro measurement. Extremely high flow rates can be achieved in vitro using large-bore catheters and delivery systems, although the clinical necessity for rates >50 L/h has not been determined. The use of large-bore extension sets resulted in only a minimal increase in flow rate. © Veterinary Emergency and Critical Care Society 2012.

  13. Optimum support by high-flow nasal cannula in acute hypoxemic respiratory failure: effects of increasing flow rates.

    Science.gov (United States)

    Mauri, Tommaso; Alban, Laura; Turrini, Cecilia; Cambiaghi, Barbara; Carlesso, Eleonora; Taccone, Paolo; Bottino, Nicola; Lissoni, Alfredo; Spadaro, Savino; Volta, Carlo Alberto; Gattinoni, Luciano; Pesenti, Antonio; Grasselli, Giacomo

    2017-10-01

    Limited data exist on the correlation between higher flow rates of high-flow nasal cannula (HFNC) and its physiologic effects in patients with acute hypoxemic respiratory failure (AHRF). We assessed the effects of HFNC delivered at increasing flow rate on inspiratory effort, work of breathing, minute ventilation, lung volumes, dynamic compliance and oxygenation in AHRF patients. A prospective randomized cross-over study was performed in non-intubated patients with patients AHRF and a PaO2/FiO2 (arterial partial pressure of oxygen/fraction of inspired oxygen) ratio of ≤300 mmHg. A standard non-occlusive facial mask and HFNC at different flow rates (30, 45 and 60 l/min) were randomly applied, while maintaining constant FiO2 (20 min/step). At the end of each phase, we measured arterial blood gases, inspiratory effort, based on swings in esophageal pressure (ΔPes) and on the esophageal pressure-time product (PTPPes), and lung volume, by electrical impedance tomography. Seventeen patients with AHRF were enrolled in the study. At increasing flow rate, HFNC reduced ΔPes (p flow rate also progressively reduced minute ventilation (p flow rates was better described by exponential fitting, while ΔEELV, V T/ΔPes and oxygenation improved linearly. In this cohort of patients with AHRF, an increasing HFNC flow rate progressively decreased inspiratory effort and improved lung aeration, dynamic compliance and oxygenation. Most of the effect on inspiratory workload and CO2 clearance was already obtained at the lowest flow rate.

  14. Silica Measurement with High Flow Rate Respirable Size Selective Samplers: A Field Study.

    Science.gov (United States)

    Lee, Taekhee; Harper, Martin; Kashon, Michael; Lee, Larry A; Healy, Catherine B; Coggins, Marie A; Susi, Pam; O'Brien, Andrew

    2016-04-01

    High and low flow rate respirable size selective samplers including the CIP10-R (10 l min(-1)), FSP10 (11.2 l min(-1)), GK2.69 (4.4 l min(-1)), 10-mm nylon (1.7 l min(-1)), and Higgins-Dewell type (2.2 l min(-1)) were compared via side-by-side sampling in workplaces for respirable crystalline silica measurement. Sampling was conducted at eight different occupational sites in the USA and five different stonemasonry sites in Ireland. A total of 536 (268 pairs) personal samples and 55 area samples were collected. Gravimetric analysis was used to determine respirable dust mass and X-ray diffraction analysis was used to determine quartz mass. Ratios of respirable dust mass concentration, quartz mass concentration, respirable dust mass, and quartz mass from high and low flow rate samplers were compared. In general, samplers did not show significant differences greater than 30% in respirable dust mass concentration and quartz mass concentration when outliers (ratio 3.0) were removed from the analysis. The frequency of samples above the limit of detection and limit of quantification of quartz was significantly higher for the CIP10-R and FSP10 samplers compared to low flow rate samplers, while the GK2.69 cyclone did not show significant difference from low flow rate samplers. High flow rate samplers collected significantly more respirable dust and quartz than low flow rate samplers as expected indicating that utilizing high flow rate samplers might improve precision in quartz measurement. Although the samplers did not show significant differences in respirable dust and quartz concentrations, other practical attributes might make them more or less suitable for personal sampling. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2015.

  15. Can hydraulic-modelled rating curves reduce uncertainty in high flow data?

    Science.gov (United States)

    Westerberg, Ida; Lam, Norris; Lyon, Steve W.

    2017-04-01

    Flood risk assessments rely on accurate discharge data records. Establishing a reliable rating curve for calculating discharge from stage at a gauging station normally takes years of data collection efforts. Estimation of high flows is particularly difficult as high flows occur rarely and are often practically difficult to gauge. Hydraulically-modelled rating curves can be derived based on as few as two concurrent stage-discharge and water-surface slope measurements at different flow conditions. This means that a reliable rating curve can, potentially, be derived much faster than a traditional rating curve based on numerous stage-discharge gaugings. In this study we compared the uncertainty in discharge data that resulted from these two rating curve modelling approaches. We applied both methods to a Swedish catchment, accounting for uncertainties in the stage-discharge gauging and water-surface slope data for the hydraulic model and in the stage-discharge gauging data and rating-curve parameters for the traditional method. We focused our analyses on high-flow uncertainty and the factors that could reduce this uncertainty. In particular, we investigated which data uncertainties were most important, and at what flow conditions the gaugings should preferably be taken. First results show that the hydraulically-modelled rating curves were more sensitive to uncertainties in the calibration measurements of discharge than water surface slope. The uncertainty of the hydraulically-modelled rating curves were lowest within the range of the three calibration stage-discharge gaugings (i.e. between median and two-times median flow) whereas uncertainties were higher outside of this range. For instance, at the highest observed stage of the 24-year stage record, the 90% uncertainty band was -15% to +40% of the official rating curve. Additional gaugings at high flows (i.e. four to five times median flow) would likely substantially reduce those uncertainties. These first results show

  16. In Vivo High Frame Rate Vector Flow Imaging Using Plane Waves and Directional Beamforming

    DEFF Research Database (Denmark)

    Jensen, Jonas; Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo

    2016-01-01

    oscillation (TO) estimators and only 3 directional beamformed lines. The suggested DB vector flow estimator is employed with steered plane wave transmissions for high frame rate imaging.Two distinct plane wave sequences are used: a short sequence(3 angles) for fast flow and an interleaved long sequence (21....... The long sequence has a higher sensitivity, and when used forestimation of slow flow with a peak velocity of 0.04 m/s, the SDis 2.5 % and bias is 0.1 %. This is a factor of 4 better than ifthe short sequence is used. The carotid bifurcation was scanned on a healthy volunteer, and the short sequence...

  17. Force and vortical flow development on pitching wings at high rates

    Science.gov (United States)

    Bernal, Luis; Yu, Huai-Te; Ol, Michael; Granlund, Kenneth

    2014-11-01

    Recent experimental results of pitching flat plate wings are presented. High pitch-rate perching maneuvers are frequently used by birds for feeding and landing. Insects use very fast rotation rates at the end of each flapping stroke, which results in high thrust and precise flight. These wing motions are also of interest for engineered micro air vehicles to achieve semi-autonomous landing by unskilled operators. The wing motion considered is a constant rotation rate pitch motion from 0 to 45 degrees of an aspect-ratio-4 flat-plate wing. The goal is to gain a better understanding of force generation mechanisms and their relationship to two- and three-dimensional vortical flow structures. Leading edge, trailing edge, and tip vortices form with large separated flow regions over the wing, however comparison with linear potential flow theory gives good agreement. The evolution of the leading edge vortex is delayed for pivot axes locations downstream of the leading edge. Large forces at the end of the motion slowly return to the steady state value over more than 30 convective times. The flow in the near wake shows a brief period of vortex shedding and strong three dimensional effects. Two different three-dimensional flow features are observed: A rapid development of three-dimensionality in the core of the leading and trailing edge vortices and a swirl motion in the near wake. However the impact of these three-dimensional flow features on force development is small.

  18. High frame rate synthetic aperture vector flow imaging for transthoracic echocardiography

    Science.gov (United States)

    Villagómez-Hoyos, Carlos A.; Stuart, Matthias B.; Bechsgaard, Thor; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt

    2016-04-01

    This work presents the first in vivo results of 2-D high frame rate vector velocity imaging for transthoracic cardiac imaging. Measurements are made on a healthy volunteer using the SARUS experimental ultrasound scanner connected to an intercostal phased-array probe. Two parasternal long-axis view (PLAX) are obtained, one centred at the aortic valve and another centred at the left ventricle. The acquisition sequence was composed of 3 diverging waves for high frame rate synthetic aperture flow imaging. For verification a phantom measurement is performed on a transverse straight 5 mm diameter vessel at a depth of 100 mm in a tissue-mimicking phantom. A flow pump produced a 2 ml/s constant flow with a peak velocity of 0.2 m/s. The average estimated flow angle in the ROI was 86.22° +/- 6.66° with a true flow angle of 90°. A relative velocity bias of -39% with a standard deviation of 13% was found. In-vivo acquisitions show complex flow patterns in the heart. In the aortic valve view, blood is seen exiting the left ventricle cavity through the aortic valve into the aorta during the systolic phase of the cardiac cycle. In the left ventricle view, blood flow is seen entering the left ventricle cavity through the mitral valve and splitting in two ways when approximating the left ventricle wall. The work presents 2-D velocity estimates on the heart from a non-invasive transthoracic scan. The ability of the method detecting flow regardless of the beam angle could potentially reveal a more complete view of the flow patterns presented on the heart.

  19. High frame rate synthetic aperture vector flow imaging for transthoracic echocardiography

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Bechsgaard, Thor

    2016-01-01

    This work presents the first in vivo results of 2-D high frame rate vector velocity imaging for transthoracic cardiac imaging. Measurements are made on a healthy volunteer using the SARUS experimental ultrasound scanner connected to an intercostal phased-array probe. Two parasternal long-axis view...... (PLAX) are obtained, one centred at the aortic valve and another centred at the left ventricle. The acquisition sequence was composed of 3 diverging waves for high frame rate synthetic aperture flow imaging. For verification a phantom measurement is performed on a transverse straight 5 mm diameter...... vessel at a depth of 100 mm in a tissue-mimicking phantom. A flow pump produced a 2 ml/s constant flow with a peak velocity of 0.2 m/s. The average estimated flow anglein the ROI was 86.22◦ ± 6.66◦ with a true flow angle of 90◦. A relative velocity bias of −39% with a standard deviation of 13% was found...

  20. Clinical effect of Diskus dry-powder inhaler at low and high inspiratory flow-rates in asthmatic children

    DEFF Research Database (Denmark)

    Nielsen, K G; Auk, I L; Bojsen, K

    1998-01-01

    In vitro studies with the Diskus inhaler at low and high flow rates show consistent doses of drug as fine particles flow independency translates into flow-independent clinical effect when the device is used by patients...... at low (30 L x min[-1]) and high (90 L x min[-1]) flow rates. A pilot study in 129 children aged 3-10 yrs demonstrated that 99% of children of 3 yrs and above can generate a flow > or = 30 L x min(-1) through the device, while 26% performed > or = 90 L x min(-1). Eighteen children aged 8-15 yrs...... after salmeterol at either flow rates as compared to placebo. There was no significant difference in the protection from salmeterol on the day of low-flow inhalation versus the day of high-flow inhalation. Consistent in vitro fine particle dosing from the Diskus inhaler translates into a consistent...

  1. Accurate Angle Estimator for High-Frame-rate 2-D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Lindskov Hansen, Kristoffer

    2016-01-01

    This paper presents a novel approach for estimating 2-D flow angles using a high-frame-rate ultrasound method. The angle estimator features high accuracy and low standard deviation (SD) over the full 360° range. The method is validated on Field II simulations and phantom measurements using the ex...... measurement is performed on a carotid bifurcation of a healthy individual. A 3-s acquisition during three heart cycles is captured. A consistent and repetitive vortex is observed in the carotid bulb during systoles....

  2. High rates of gene flow by pollen and seed in oak populations across Europe.

    Directory of Open Access Journals (Sweden)

    Sophie Gerber

    Full Text Available Gene flow is a key factor in the evolution of species, influencing effective population size, hybridisation and local adaptation. We analysed local gene flow in eight stands of white oak (mostly Quercus petraea and Q. robur, but also Q. pubescens and Q. faginea distributed across Europe. Adult trees within a given area in each stand were exhaustively sampled (range [239, 754], mean 423, mapped, and acorns were collected ([17,147], 51 from several mother trees ([3], [47], 23. Seedlings ([65,387], 178 were harvested and geo-referenced in six of the eight stands. Genetic information was obtained from screening distinct molecular markers spread across the genome, genotyping each tree, acorn or seedling. All samples were thus genotyped at 5-8 nuclear microsatellite loci. Fathers/parents were assigned to acorns and seedlings using likelihood methods. Mating success of male and female parents, pollen and seed dispersal curves, and also hybridisation rates were estimated in each stand and compared on a continental scale. On average, the percentage of the wind-borne pollen from outside the stand was 60%, with large variation among stands (21-88%. Mean seed immigration into the stand was 40%, a high value for oaks that are generally considered to have limited seed dispersal. However, this estimate varied greatly among stands (20-66%. Gene flow was mostly intraspecific, with large variation, as some trees and stands showed particularly high rates of hybridisation. Our results show that mating success was unevenly distributed among trees. The high levels of gene flow suggest that geographically remote oak stands are unlikely to be genetically isolated, questioning the static definition of gene reserves and seed stands.

  3. Prediction of Ablation Rates from Solid Surfaces Exposed to High Temperature Gas Flow

    Science.gov (United States)

    Akyuzlu, Kazim M.; Coote, David

    2013-01-01

    A mathematical model and a solution algorithm is developed to study the physics of high temperature heat transfer and material ablation and identify the problems associated with the flow of hydrogen gas at very high temperatures and velocities through pipes and various components of Nuclear Thermal Rocket (NTR) motors. Ablation and melting can be experienced when the inner solid surface of the cooling channels and the diverging-converging nozzle of a Nuclear Thermal Rocket (NTR) motor is exposed to hydrogen gas flow at temperatures around 2500 degrees Kelvin and pressures around 3.4 MPa. In the experiments conducted on typical NTR motors developed in 1960s, degradation of the cooling channel material (cracking in the nuclear fuel element cladding) and in some instances melting of the core was observed. This paper presents the results of a preliminary study based on two types of physics based mathematical models that were developed to simulate the thermal-hydrodynamic conditions that lead to ablation of the solid surface of a stainless steel pipe exposed to high temperature hydrogen gas near sonic velocities. One of the proposed models is one-dimensional and assumes the gas flow to be unsteady, compressible and viscous. An in-house computer code was developed to solve the conservations equations of this model using a second-order accurate finite-difference technique. The second model assumes the flow to be three-dimensional, unsteady, compressible and viscous. A commercial CFD code (Fluent) was used to solve the later model equations. Both models assume the thermodynamic and transport properties of the hydrogen gas to be temperature dependent. In the solution algorithm developed for this study, the unsteady temperature of the pipe is determined from the heat equation for the solid. The solid-gas interface temperature is determined from an energy balance at the interface which includes heat transfer from or to the interface by conduction, convection, radiation, and

  4. Nanoimprinted distributed feedback dye laser sensors for high frame rate refractometric imaging of dissolution and fluid flow

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Sørensen, Kristian Tølbøl; Gade, Carsten

    2015-01-01

    High frame rate refractometric dissolution and fluid flow monitoring in one and two dimensions of space with distributed feedback dye laser sensors is presented. The sensors provide both low detection limits and high spatial resolution. © 2015 OSA.......High frame rate refractometric dissolution and fluid flow monitoring in one and two dimensions of space with distributed feedback dye laser sensors is presented. The sensors provide both low detection limits and high spatial resolution. © 2015 OSA....

  5. A high sensitivity fiber optic macro-bend based gas flow rate transducer for low flow rates: Theory, working principle, and static calibration

    Science.gov (United States)

    Schena, Emiliano; Saccomandi, Paola; Silvestri, Sergio

    2013-02-01

    A novel fiber optic macro-bend based gas flowmeter for low flow rates is presented. Theoretical analysis of the sensor working principle, design, and static calibration were performed. The measuring system consists of: an optical fiber, a light emitting diode (LED), a Quadrant position sensitive Detector (QD), and an analog electronic circuit for signal processing. The fiber tip undergoes a deflection in the flow, acting like a cantilever. The consequent displacement of light spot center is monitored by the QD generating four unbalanced photocurrents which are function of fiber tip position. The analog electronic circuit processes the photocurrents providing voltage signal proportional to light spot position. A circular target was placed on the fiber in order to increase the sensing surface. Sensor, tested in the measurement range up to 10 l min-1, shows a discrimination threshold of 2 l min-1, extremely low fluid dynamic resistance (0.17 Pa min l-1), and high sensitivity, also at low flow rates (i.e., 33 mV min l-1 up to 4 l min-1 and 98 mV min l-1 from 4 l min-1 up to 10 l min-1). Experimental results agree with the theoretical predictions. The high sensitivity, along with the reduced dimension and negligible pressure drop, makes the proposed transducer suitable for medical applications in neonatal ventilation.

  6. Vertical multiphase flow correlations for high production rates and large tubulars

    Energy Technology Data Exchange (ETDEWEB)

    Aggour, M.A.; Al-Yousef, H.Y. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Muraikhi, A.J.

    1996-02-01

    Numerous correlations exist for predicting pressure drop in vertical multiphase flow. These correlations, however, were all developed and tested under limited operating conditions that do not match the high production rates and large tubulars normally found in the Middle East fields. This paper presents a comprehensive evaluation of existing correlations and modifications of some correlations to determine and recommend the best correlation or correlations for various field conditions. More than 400 field data sets covering tubing sizes from 2 3/8 to 7 inches, oil rates up to 23,200 B/D, water cuts up to 95%, and gas/oil ratio (GOR) up to 927 scf/STB were used in this study. Considering all data combined, the Beggs and Brill correlation provided the best pressure predictions. However, the Hagedorn and Brown correlation was better for water cuts above 80%, while the Hasan and Kabir model was better for total liquid rates above 20,000 B/D. The Aziz correlation was significantly improved when the Orkiszewski flow-pattern transition criteria were used.

  7. Using NIF to Test Theories of High-Pressure, High-Rate Plastic Flow in Metals

    Science.gov (United States)

    Rudd, Robert E.; Arsenlis, A.; Cavallo, R. M.; Huntington, C. M.; McNaney, J. M.; Park, H. S.; Powell, P.; Prisbrey, S. T.; Remington, B. A.; Swift, D.; Wehrenberg, C. E.; Yang, L.

    2017-10-01

    Precisely controlled plasmas are playing key roles both as pump and probe in experiments to understand the strength of solid metals at high energy density (HED) conditions. In concert with theoretical advances, these experiments have enabled a predictive capability to model material strength at Mbar pressures and high strain rates. Here we describe multiscale strength models developed for tantalum starting with atomic bonding and extending up through the mobility of individual dislocations, the evolution of dislocation networks and so on until the ultimate material response at the scale of an experiment. Experiments at the National Ignition Facility (NIF) probe strength in metals ramp compressed to 1-8 Mbar. The model is able to predict 1 Mbar experiments without adjustable parameters. The combination of experiment and theory has shown that solid metals can behave significantly differently at HED conditions. We also describe recent studies of lead compressed to 3-5 Mbar. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA273.

  8. Ion-pair ultra-high performance liquid chromatographic analysis of monoamines: peak-splitting at high flow rates.

    Science.gov (United States)

    Van Schoors, Jolien; Brouwer, Hendrik-Jan; Maes, Katrien; Michotte, Yvette; Van Eeckhaut, Ann

    2013-12-20

    The use of ion-pair ultra-high performance liquid chromatography (UHPLC) coupled with electrochemical detection (ECD) is of great interest for the fast and sensitive determination of the monoamine neurotransmitters dopamine, noradrenaline and serotonin in microdialysis samples. However, when applying high flow rates in ion-pair UHPLC, other peaks than the initial compound peaks appear on the chromatogram. This peak-splitting phenomenon is caused by disturbed ion-pair retention mechanisms. The influence of several chromatographic parameters is investigated. Peak-splitting is delayed to higher flow rates when increasing the concentration of ion-pair reagent or buffering agent in the mobile phase, when decreasing the percentage of organic modifier in the mobile phase, when applying a stationary phase with a smaller amount of packing material or when increasing the separation temperature. One or a combination of these conditions can be applied to analyze the monoamine neurotransmitters using ion-pair UHPLC-ECD at high flow rates. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Enabling high-rate electrochemical flow capacitors based on mesoporous carbon microspheres suspension electrodes

    Science.gov (United States)

    Tian, Meng; Sun, Yueqing; Zhang, Chuanfang (John); Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

    2017-10-01

    Electrochemical flow capacitor (EFC) is a promising technology for grid energy storage, which combines the fast charging/discharging capability of supercapacitors with the scalable energy capacity of flow batteries. In this study, we report a high-power-density EFC using mesoporous carbon microspheres (MCMs) as suspension electrodes. By using a simple yet effective spray-drying technique, monodispersed MCMs with average particle size of 5 μm, high BET surface area of 1150-1267 m2 g-1, large pore volume of 2-4 cm3 g-1 and controllable mesopore size of 7-30 nm have been successfully prepared. The resultant MCMs suspension electrode shows excellent stability and considerable high capacitance of 100 F g-1 and good cycling ability (86% of initial capacitance after 10000 cycles). Specially, the suspension electrode exhibits excellent rate performance with 75% capacitance retention from 2 to 100 mV s-1, significantly higher than that of microporous carbon electrodes (20∼30%), due to the developed mesoporous channels facilitating for rapid ion diffusion. In addition, the electrochemical responses on both negative and positive suspension electrodes are studied, based on which an optimal capacitance matching between them is suggested for large-scale EFC unit.

  10. Antibody-Functionalized Fluid-Permeable Surfaces for Rolling Cell Capture at High Flow Rates

    Science.gov (United States)

    Mittal, Sukant; Wong, Ian Y.; Deen, William M.; Toner, Mehmet

    2012-01-01

    Adhesion-based cell capture on surfaces in microfluidic devices forms the basis of numerous biomedical diagnostics and in vitro assays. However, the performance of these platforms is partly limited by interfacial phenomena that occur at low Reynolds numbers. In contrast, cell homing to porous vasculature is highly effective in vivo during inflammation, stem cell trafficking, and cancer metastasis. Here, we show that a porous, fluid-permeable surface functionalized with cell-specific antibodies promotes efficient and selective cell capture in vitro. This architecture is advantageous due to enhanced transport as streamlines are diverted toward the surface. Moreover, specific cell-surface interactions are promoted due to reduced shear, allowing gentle cell rolling and arrest. Together, these synergistic effects enable highly effective cell capture at flow rates more than an order of magnitude larger than those provided by existing devices with solid surfaces. PMID:22385842

  11. Endothelial cell dynamics under pulsating flows: significance of high versus low shear stress slew rates (d(tau)/dt).

    Science.gov (United States)

    Hsiai, Tzung K; Cho, Sung K; Honda, Henry M; Hama, Susan; Navab, Mohamad; Demer, Linda L; Ho, Chih-Ming

    2002-05-01

    Shear stress modulates endothelial cell (EC) remodeling via realignment and elongation. We provide the first evidence that the upstroke slopes of pulsatile flow, defined as shear stress slew rates (positive d(tau)/dt), affect significantly the rates at which ECs remodel. We designed a novel flow system to isolate various shear stress slew rates by precisely controlling the frequency, amplitude, and time-averaged shear stress (tau(ave)) of pulsatile flow. Bovine aortic endothelial cell (BAEC) monolayers were exposed to three conditions: (1) pulsatile flow (1 Hz) at high slew rate (293 dyn/cm2 s), (2) pulsatile flow (1 Hz) at low slew rate (71 dyn/cm2s), and (3) steady laminar flow at d(tau)/dt = 0. All of the three conditions were operated at tau(ave) = 50 dyn/cm2. BAEC elongation and alignment were measured over 17 h. We were able to demonstrate the effects of shear stress slew rates ((tau)/dt) on EC remodeling at a fixed spatial shear stress gradient (d(tau)/dx). We found that pulsatile flow significantly increased the rates at which EC elongated and realigned, compared to steady flow at d(tau)/dt = 0. Furthermore, EC remodeling was faster in response to high than to low slew rates at a given tau(ave).

  12. Thermodynamic Characteristic Study of a High-temperature Flow-rate Control Valve for Fuel Supply of Scramjet Engines

    National Research Council Canada - National Science Library

    ZENG Wen TONG Zhizhong LI Songjing LI Hongzhou ZHANG Liang

    2012-01-01

    ... and increasing of leakage,to the valve.In this paper,a high-temperature flow-rate control valve,pilot-controlled by a pneumatic servo system is developed to control the fuel supply for scramjet...

  13. Apparatus and method for tuned unsteady flow purging of high pulse rate spark gaps

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, W.J. III.

    1988-10-12

    A spark gap switch apparatus is disclosed which is capable of operating at a high pulse rate which comprises an insulated housing; a pair of spaced apart electrodes each having one end thereof within a first bore formed in the housing and defining a spark gap therebetween; pressure wave reflector means in the first bore in the housing and spaced from the spark gap and capable of admitting purge flow; and a second enlarged bore contiguous with the first bore and spaced from the opposite side of the spark gap; whereby pressure waves generated during discharge of a spark across the spark gap will reflect off the wave reflector means and back from the enlarged bore to the spark gap to clear from the spark gap hot gases residues generated during the discharge and simultaneously restore the gas density and pressure in the spark gap to its initial value. 8 figs.

  14. Apparatus and method for tuned unsteady flow purging of high pulse rate spark gaps

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, III, William J. (Kent, WA)

    1990-01-01

    A spark gap switch apparatus is disclosed which is capable of operating at a high pulse rate which comprises an insulated housing; a pair of spaced apart electrodes each having one end thereof within a first bore formed in the housing and defining a spark gap therebetween; a pressure wave reflector in the first bore in the housing and spaced from the spark gap and capable of admitting purge flow; and a second enlarged bore contiguous with the first bore and spaced from the opposite side of the spark gap; whereby pressure waves generated during discharge of a spark across the spark gap will reflect off the wave reflector and back from the enlarged bore to the spark gap to clear from the spark gap hot gases residues generated during the discharge and simultaneously restore the gas density and pressure in the spark gap to its initial value.

  15. Very-high-flow injection rate for upper abdominal CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Masashi; Minamiguti, Hiroki; Hagihira, Takami; Kishi, Kazushi; Sato, Morio [Wakayama Medical Coll. (Japan); Shioyama, Yasukazu; Okumura, Toshiyuki; Yamada, Kouji; Kawashima, Michihisa [Central Hospital and Cancer Center of Ibaraki Prefecture, Tomobe (Japan)

    2002-06-01

    The purpose of this study was to compare a very-high-flow injection-rate method (group A) and a conventional injection-rate method (group B) for visualization of upper abdominal arteries by multidetector helical computed tomography (MDHCT). The subjects were 240 patients suspected to have abdominal lesions. They were randomly assigned to group A (120 patients) and group B (120 patients). In group A, the bilateral medial cubital veins were punctured, and contrast medium was infused at a rate of 8.6-9.6 ml/s. In group B, the unilateral medial cubital vein was punctured, and contrast medium was infused at a rate of 2.0-3.0 ml/s. The quality of vascular visualization was graded as poor, good, or excellent by three radiologists. All visualizations of the celiac trunk (CE) and superior mesenteric artery (SMA) were graded as excellent in both group A and group B. Visualization grades of the subsegmental branches of the hepatic artery (HA), right gastric artery (RGA), cystic artery, dorsal pancreatic artery (DPA), and superior pancreaticoduodenal artery (SPDA) were good or excellent in 75% (paging method)/53.3% (three-dimensional method), 85%/30%, 77.7%/18.3%, 76.7%/28.3%, and 88.3%/42.5%, respectively, in group A, and 33.3%/11.7%, 46.7%/3.4%, 41.6%/5%, 55%/4.2%, and 72.5%/14.2%, respectively, in group B. The appearance rate of intrahepatic portal branches was 28.3% in group A and 66.7% in group B in the arterial dominant phase. Group A showed better visualization results than Group B in upper abdominal arteries according to MDHCT. (author)

  16. Feeding an infant with high arched palate by high flow rate bottle nipple.

    Science.gov (United States)

    Eren, Abdulkadir; Bilgin, Huseyin; Kara, Semra

    2015-01-01

    For infants with high arched palate, feeding is one of the most immediate challenges faced by parents and caretakers. General suggestions for feeding in infants with cleft palate may be adapted to infants with high arched palate. These include oral feeding facilitation techniques and special feeding tools. Here we present a newborn with a high arched palate and serious feeding problems who was fed easily by a large size and a large hole nipple, ordinarily used for infants older than 6 months, instead of specialized feeding equipment.

  17. Prediction of FV520B Steel Flow Stresses at High Temperature and Strain Rates

    Science.gov (United States)

    Han, Xiaolan; Zhao, Shengdun; Zhang, Chenyang; Fan, Shuqin; Xu, Fan

    2015-10-01

    In order to develop reliable constitutive equations for the simulation, the hot deformation behavior of FV520B steel was investigated through isothermal compression tests in a wide range of temperatures from 900 °C to 1100 °C at an interval of 50 °C and strain rate from 0.01 to 10 s-1 on Gleeble-1500D simulator. The effects of temperature and strain rate on deformation behavior were represented by Zener-Holloman parameter in an exponent-type equation of Arrhenius constitutive. The influence of strain was incorporated in the constitutive analysis by material constants expressed as a polynomial function of strain. The constitutive equation (considering the compensation of strain) could precisely predict the flow stress only at strain rate 0.01 s-1 except at the temperatures of 900 °C and 1000 °C, whereas the flow stress predicted by a modified equation (incorporating both the strain and strain rate) demonstrated a well agreement with the experimental data throughout the entire range of temperatures and strain rates. Correlation coefficient (R) of 0.988 and average absolute relative error (AARE) of 5.7% verified the validity of developed equation from statistical analysis, which further confirmed that the modified constitutive equation could accurately predict the flow stress of FV520B steel.

  18. Intergenic DNA sequences from the human X chromosome reveal high rates of global gene flow

    Directory of Open Access Journals (Sweden)

    Wall Jeffrey D

    2008-11-01

    Full Text Available Abstract Background Despite intensive efforts devoted to collecting human polymorphism data, little is known about the role of gene flow in the ancestry of human populations. This is partly because most analyses have applied one of two simple models of population structure, the island model or the splitting model, which make unrealistic biological assumptions. Results Here, we analyze 98-kb of DNA sequence from 20 independently evolving intergenic regions on the X chromosome in a sample of 90 humans from six globally diverse populations. We employ an isolation-with-migration (IM model, which assumes that populations split and subsequently exchange migrants, to independently estimate effective population sizes and migration rates. While the maximum effective size of modern humans is estimated at ~10,000, individual populations vary substantially in size, with African populations tending to be larger (2,300–9,000 than non-African populations (300–3,300. We estimate mean rates of bidirectional gene flow at 4.8 × 10-4/generation. Bidirectional migration rates are ~5-fold higher among non-African populations (1.5 × 10-3 than among African populations (2.7 × 10-4. Interestingly, because effective sizes and migration rates are inversely related in African and non-African populations, population migration rates are similar within Africa and Eurasia (e.g., global mean Nm = 2.4. Conclusion We conclude that gene flow has played an important role in structuring global human populations and that migration rates should be incorporated as critical parameters in models of human demography.

  19. Plane-wave transverse oscillation for high-frame-rate 2-D vector flow imaging.

    Science.gov (United States)

    Lenge, Matteo; Ramalli, Alessandro; Tortoli, Piero; Cachard, Christian; Liebgott, Hervé

    2015-12-01

    Transverse oscillation (TO) methods introduce oscillations in the pulse-echo field (PEF) along the direction transverse to the ultrasound propagation direction. This may be exploited to extend flow investigations toward multidimensional estimates. In this paper, the TOs are coupled with the transmission of plane waves (PWs) to reconstruct high-framerate RF images with bidirectional oscillations in the pulse-echo field. Such RF images are then processed by a 2-D phase-based displacement estimator to produce 2-D vector flow maps at thousands of frames per second. First, the capability of generating TOs after PW transmissions was thoroughly investigated by varying the lateral wavelength, the burst length, and the transmission frequency. Over the entire region of interest, the generated lateral wavelengths, compared with the designed ones, presented bias and standard deviation of -3.3 ± 5.7% and 10.6 ± 7.4% in simulations and experiments, respectively. The performance of the ultrafast vector flow mapping method was also assessed by evaluating the differences between the estimated velocities and the expected ones. Both simulations and experiments show overall biases lower than 20% when varying the beam-to-flow angle, the peak velocity, and the depth of interest. In vivo applications of the method on the common carotid and the brachial arteries are also presented.

  20. Design and Analysis of a High Force, Low Voltage and High Flow Rate Electro-Thermal Micropump

    Directory of Open Access Journals (Sweden)

    Ghader Yosefi

    2014-12-01

    Full Text Available This paper presents the design and simulation of an improved electro-thermal micromachined pump for drug delivery applications. Thermal actuators, which are a type of Micro Electro Mechanical system (MEMS device, are highly useful because of their ability to deliver with great force and displacement. Thus, our structure is based on a thermal actuator that exploits the Joule heating effect and has been improved using the springy length properties of MEMS chevron beams. The Joule heating effect results in a difference in temperature and therefore displacement in the beams (actuators. Simulation results show that a maximum force of 4.4 mN and a maximum flow rate of 16 μL/min can be obtained by applying an AC voltage as low as 8 V at different frequencies ranging from 1 to 32 Hz. The maximum temperature was a problem at the chevron beams and the center shaft. Thus, to locally increase the temperature of the chevron beams alone and not that of the pumping diaphragm: (1 The air gaps 2 μm underneath and above the device layer were optimized for heat transfer. (2 Release holes and providing fins were created at the center shaft and actuator, respectively, to decrease the temperature by approximately 10 °C. (3 We inserted and used a polymer tube to serve as an insulator and eliminate leakage problems in the fluidic channel.

  1. Coronary CT angiography using low concentrated contrast media injected with high flow rates: Feasible in clinical practice.

    Science.gov (United States)

    Mihl, Casper; Kok, Madeleine; Wildberger, Joachim E; Altintas, Sibel; Labus, David; Nijssen, Estelle C; Hendriks, Babs M F; Kietselaer, Bas L J H; Das, Marco

    2015-11-01

    Aim of this study was to test the hypothesis that peak injection pressures and image quality using low concentrated contrast media (CM) (240 mg/mL) injected with high flow rates will be comparable to a standard injection protocol (CM: 300 mg/mL) in coronary computed tomographic angiography (CCTA). One hundred consecutive patients were scanned on a 2nd generation dual-source CT scanner. Group 1 (n=50) received prewarmed Iopromide 240 mg/mL at an injection rate of 9 mL/s, followed by a saline chaser. Group 2 (n=50) received the standard injection protocol: prewarmed Iopromide 300 mg/mL; flow rate: 7.2 mL/s. For both protocols, the iodine delivery rate (IDR, 2.16 gI/s) and the total iodine load (22.5 gI) were kept identical. Injection pressure (psi) was continuously monitored by a data acquisition program. Contrast enhancement was measured in the thoracic aorta and all proximal and distal coronary segments. Subjective and objective image quality was evaluated between both groups. No significant differences in peak injection pressures were found between both CM groups (121 ± 5.6 psi vs. 120 ± 5.3 psi, p=0.54). Flow rates of 9 mL/s were safely injected without any complications. No significant differences in contrast-to-noise ratio, signal-to-noise ratio and subjective image quality were found (all p>0.05). No significant differences in attenuation levels were found in the thoracic aorta and all segments of the coronary arteries (all p>0.05). Usage of low iodine concentration CM and injection with high flow rates is feasible. High flow rates (9 mL/s) of Iopromide 240 were safely injected without complications and should not be considered a drawback in clinical practice. No significant differences in peak pressure and image quality were found. This creates a doorway towards applicability of a broad variety in flow rates and IDRs and subsequently more individually tailored injection protocols. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  2. High shear rate flow in a linear stroke magnetorheological energy absorber

    Science.gov (United States)

    Hu, W.; Wereley, N. M.; Hiemenz, G. J.; Ngatu, G. T.

    2014-05-01

    To provide adaptive stroking load in the crew seats of ground vehicles to protect crew from blast or impact loads, a magnetorheological energy absorber (MREA) or shock absorber was developed. The MREA provides appropriate levels of controllable stroking load for different occupant weights and peak acceleration because the viscous stroking load generated by the MREA force increases with velocity squared, thereby reducing its controllable range at high piston velocity. Therefore, MREA behavior at high piston velocity is analyzed and validated experimentally in order to investigate the effects of velocity and magnetic field on MREA performance. The analysis used to predict the MREA force as a function of piston velocity squared and applied field is presented. A conical fairing is mounted to the piston head of the MREA in order reduce predicted inlet flow loss by 9% at nominal velocity of 8 m/s, which resulted in a viscous force reduction of nominally 4%. The MREA behavior is experimentally measured using a high speed servo-hydraulic testing system for speeds up to 8 m/s. The measured MREA force is used to validate the analysis, which captures the transient force quite accurately, although the peak force is under-predicted at the peak speed of 8 m/s.

  3. A field-programmable gate array based system for high frame rate laser Doppler blood flow imaging.

    Science.gov (United States)

    Nguyen, H C; Hayes-Gill, B R; Morgan, S P; Zhu, Y; Boggett, D; Huang, X; Potter, M

    2010-01-01

    This paper presents a general embedded processing system implemented in a field-programmable gate array providing high frame rate and high accuracy for a laser Doppler blood flow imaging system. The proposed system can achieve a basic frame rate of flow images at 1 frame/second for 256 x 256 images with 1024 fast Fourier transform (FFT) points used in the processing algorithm. Mixed fixed-floating point calculations are utilized to achieve high accuracy but with a reasonable resource usage. The implementation has a root mean square deviation of the relative difference in flow values below 0.1% when compared with a double-precision floating point implementation. The system can contain from one or more processing units to obtain the required frame rate and accuracy. The performance of the system is significantly higher than other methods reported to date. Furthermore, a dedicated field-programmable gate array (FPGA) board has been designed to test the proposed processing system. The board is linked with a laser line scanning system, which uses a 64 x 1 photodetector array. Test results with various operating parameters show that the performance of the new system is better, in terms of noise and imaging speed, than has been previously achieved.

  4. Intracardiac Vortex Dynamics by High-Frame-Rate Doppler Vortography-In Vivo Comparison With Vector Flow Mapping and 4-D Flow MRI.

    Science.gov (United States)

    Faurie, Julia; Baudet, Mathilde; Assi, Kondo Claude; Auger, Dominique; Gilbert, Guillaume; Tournoux, Francois; Garcia, Damien

    2017-02-01

    Recent studies have suggested that intracardiac vortex flow imaging could be of clinical interest to early diagnose the diastolic heart function. Doppler vortography has been introduced as a simple color Doppler method to detect and quantify intraventricular vortices. This method is able to locate a vortex core based on the recognition of an antisymmetric pattern in the Doppler velocity field. Because the heart is a fast-moving organ, high frame rates are needed to decipher the whole blood vortex dynamics during diastole. In this paper, we adapted the vortography method to high-frame-rate echocardiography using circular waves. Time-resolved Doppler vortography was first validated in vitro in an ideal forced vortex. We observed a strong correlation between the core vorticity determined by high-frame-rate vortography and the ground-truth vorticity. Vortography was also tested in vivo in ten healthy volunteers using high-frame-rate duplex ultrasonography. The main vortex that forms during left ventricular filling was tracked during two-three successive cardiac cycles, and its core vorticity was determined at a sampling rate up to 80 duplex images per heartbeat. Three echocardiographic apical views were evaluated. Vortography-derived vorticities were compared with those returned by the 2-D vector flow mapping approach. Comparison with 4-D flow magnetic resonance imaging was also performed in four of the ten volunteers. Strong intermethod agreements were observed when determining the peak vorticity during early filling. It is concluded that high-frame-rate Doppler vortography can accurately investigate the diastolic vortex dynamics.

  5. Assessment of Impact of High Particulate Concentration on Peak Expiratory Flow Rate of Lungs of Sand Stone Quarry Workers

    Directory of Open Access Journals (Sweden)

    Gopal Purohit

    2006-12-01

    Full Text Available This study was designed to assess the impact of high particulate concentration on peak expiratory flow rate of lungs of sand stone quarry workers. The workers were engaged in different types of activities such as drilling, loading and dressing. These different working conditions had different concentrations of RSPM, leading to different exposure levels in workers. It was found that exposure duration and exposure concentrations were the main factors responsible for damage to the respiratory tracts of the workers. The particles were deposited at various areas of the respiratory system and reduced the peak flow rate. It was also revealed from the study that most of the workers suffered from silicosis if the exposure duration was more than 20 years.

  6. Apparatus and method for tunes unsteady flow purging of high pulse rate spark gaps

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, W.J. III.

    1990-11-13

    This patent describes a spark gap switch apparatus capable of operating at a high pulse rate. It comprises: an insulated housing; a pair of spaced apart electrodes each having one end thereof within a first bore formed in the housing and defining a spark gap therebetween; pressure wave reflector means in the first bore in the housing and spaced from the spark gap; and a second enlarged bore contiguous with the first bore and spaced from the opposite side of the spark gap from the wave reflector means; whereby pressure waves generated during discharge of a spark across the spark gap will reflect off the reflector means and back from the enlarged bore to the spark gap to clear from the spark gap hot gas residues generated during the discharge and reestablish the initial pressure and density of purge gas within the spark gap.

  7. Photogrammetric Measurement of Recession Rates of Low Temperature Ablators Subjected to High Speed Flow

    Science.gov (United States)

    2011-06-01

    approximately 20 to 30 seconds ( Bjorge , Reeder, Subramanian, Crafton, & Fonov, 2005). 49 Figure 8 illustrates the tunnel with the Mach 2.94...Astronautics, Inc. Bjorge , S., Reeder, M., Subramanian, C., Crafton, J., & Fonov, S. (2005). Flow Around an Object Projected from a Cavity into a Supersonic

  8. A Modified Johnson-Cook Model for Flow Behavior of Alloy 800H at Intermediate Strain Rates and High Temperatures

    Science.gov (United States)

    Shokry, Abdallah

    2017-12-01

    A modified Johnson-Cook model for the flow behavior of alloy 800H at intermediate strain rates and high temperatures is presented. The modification is based on a study of the relation between strain hardening and both strain rate and softening parameters. The predicted stresses obtained using the modified model are compared to those obtained using the original Johnson-Cook model. The parameters constitute the two models are determined using the inverse method, Kalman filter. The results show that the modified model fits the experimental data very well for different combinations of strain rates and temperatures, with a mean value of R-squared regression of 0.90 for the modified model and 0.74 for the original Johnson-Cook model.

  9. A new concept of high flow rate non-thermal plasma reactor for air treatment

    Energy Technology Data Exchange (ETDEWEB)

    Goujard, V.; Tatibouet, J.M. [Univ. de Poitiers, Poitiers (France). Centre national de la recherche scientifique, Laboratoire de Catalyse en Chimie Organique

    2010-07-01

    Although several non-thermal plasma reactors have been tested for air treatment at the laboratory scale, up-scaling to pilot or industrial scale remains a challenge because several parameters must be considered, such as hydrodynamic behaviour, maximum voltage in an industrial environment, and maintenance of the system. This paper presented a newly developed reactor which consists to a DBD plasma generated on individual supports that could be directly inserted in gas pipes where air flow must be treated. Elimination of 40 percent of 15 ppm of propene was obtained with a energy density as low as 10 J/L. The propene conversion increased when a manganese oxide based catalyst was used because the ozone produced by the plasma was used as an as an oxidant. A simple model of the plasma-catalyst reactor behaviour showed that more than 90 percent of propene conversion can be expected for an input energy density of 10 J/L and residual ozone concentration less than 100 ppb.

  10. Peripheral intravenous power injection of iodinated contrast media through 22G and 20G cannulas: can high flow rates be achieved safely? A clinical feasibility study.

    Science.gov (United States)

    Schwab, S A; Uder, M; Anders, K; Heinrich, M C; Kuefner, M A

    2009-04-01

    Modern examination protocols for computed tomography (CT) often require high injection rates of iodinated contrast media (CM). The purpose of this study was to evaluate the maximum achievable flow rates and stability of different peripheral intravenous catheters (IVC) in vitro and to assess the feasibility of higher injection rates through small IVC in vivo. For in vitro experiments flow measurements followed by high pressure testing of different types of IVC (22, 20, and 18 gauge [G]) were performed. For the in vitro study 91 patients with already inserted 22 or 20G IVC who had been referred for CT received Iopamidol (300 mg iodine/ml) at flow rates between 2 and 5 ml/sec. Complications were documented. The maximal achievable flow rate of the tested IVC in vitro ranged from 5 to 8 ml/sec. No damage was observed during in vitro testing. The initially targeted in vivo flow rate was dropped in 33 of 91 (36 %) patients because the IVC could not be flushed adequately with saline before CM injection. Extravasation of CM occurred in 2 cases. In the remaining 58 patients the standard CT protocol was performed with flow rates of 3 ml/sec through 22G IVC and 5 ml/sec through 20G IVC, respectively. In this group, the extravasation of CM was observed twice (p > 0.05). Even with highly viscous CM, high flow rates can be applied in vitro in 22, 20, and 18G IVC without risking material damage. In vivo power injection of iodinated CM through 22G and 20G IVC seems to be safely achievable in the majority of patients with flow rates of up to 3 ml/sec and 5 ml/sec. Extravasation rates do not differ significantly between patients with high-flow or low-flow injections.

  11. Modeling High Rate Phosphorus and Nitrogen Removal in a Vertical Flow Alum Sludge based Constructed Wetlands

    Science.gov (United States)

    Jeyakumar, Lordwin; Zhao, Yaqian

    2014-05-01

    Increased awareness of the impacts of diffuse pollution and their intensification has pushed forward the need for the development of low-cost wastewater treatment techniques. One of such efforts is the use of novel DASC (Dewatered Alum Sludge Cakes) based constructed wetlands (CWs) for removing nutrients, organics, trace elements and other pollutants from wastewater. Understanding of the processes in CWs requires a numerical model that describes the biochemical transformation and degradation processes in subsurface vertical flow (VF) CWs. Therefore, this research focuses on the development of a process-based model for phosphorus (P) and nitrogen (N) removal to achieve a stable performance by using DASC as a substrate in CWs treatment system. An object-oriented modelling tool known as "STELLA" which works based on the principle of system dynamics is used for the development of P and N model. The core objective of the modelling work is oriented towards understanding the process in DASC-based CWs and optimizes design criteria. The P and N dynamic model is developed for DASC-based CWs. The P model developed exclusively for DASC-based CW was able to simulate the effluent P concentration leaving the system satisfactorily. Moreover, the developed P dynamic model has identified the major P pathways as adsorption (72%) followed by plant uptake (20%) and microbial uptake (7%) in single-stage laboratory scale DASC-based CW. Similarly, P dynamic simulation model was developed to simulate the four-stage laboratory scale DASC-based CWs. It was found that simulated and observed values of P removal were in good agreement. The fate of P in all the four stages clearly shows that adsorption played a pivotal role in each stage of the system due to the use of the DASC as a substrate. P adsorption by wetland substrate/DASC represents 59-75% of total P reduction. Subsequently, plant uptake and microbial uptake have lesser role regarding P removal (as compared to adsorption).With regard

  12. Columbus Payloads Flow Rate Anomalies

    Science.gov (United States)

    Quaranta, Albino; Bufano, Gaetana; DePalo, Savino; Holt, James M.; Szigetvari, Zoltan; Palumberi, Sergio; Hinderer, S.

    2011-01-01

    The Columbus Active Thermal Control System (ATCS) is the main thermal bus for the pressurized racks working inside the European laboratory. One of the ATCS goals is to provide proper water flow rate to each payload (P/L) by controlling actively the pressure drop across the common plenum distribution piping. Overall flow measurement performed by the Water Pump Assembly (WPA) is the only flow rate monitor available at system level and is not part of the feedback control system. At rack activation the flow rate provided by the system is derived on ground by computing the WPA flow increase. With this approach, several anomalies were raised during these 3 years on-orbit, with the indication of low flow rate conditions on the European racks FSL, BioLab, EDR and EPM. This paper reviews the system and P/Ls calibration approach, the anomalies occurred, the engineering evaluation on the measurement approach and the accuracy improvements proposed, the on-orbit test under evaluation with NASA and finally discusses possible short and long term solutions in case of anomaly confirmation.

  13. Flexible Membrane Micro Flow-rate Threshold Flow Sensor

    Directory of Open Access Journals (Sweden)

    Hee C. LIM

    2007-12-01

    Full Text Available A piezoresistive flow sensor that functions as a threshold flow switch, independent of input supply voltage, is designed, fabricated, and tested. The test flow rate is in the 10s ml/hr range. The sensor is fabricated using doped hydrogenated amorphous silicon thin film with MEMs on flexible polyimide substrate. The flow sensor is highly sensitive and able to distinguish between distilled water and 0.1 % NaCl saline solution in terms of threshold switch-on flow rate. The switch-on threshold of the flow sensor is observed to be independent of the applied input voltage. These turn-on threshold levels are adaptable to user’s application.

  14. Stability of flow focusing: The minimum attainable flow rate

    Science.gov (United States)

    Montanero, J. M.; Rebollo, N.; Acero, A.; Ferrera, C.; Herrada, M. A.; Ganan-Calvo, A. M.

    2011-11-01

    We analyze both theoretically and experimentally the stability of the steady jetting regime reached when liquid jets are focused by coaxial gas streams. In the low-viscosity case, viscous dissipation in the feeding capillary and liquid meniscus seem to be the origin of the instability. For high-viscosity liquids, the breakdown of the jetting regime takes place when the pressure drop cannot overcome the resistance force offered by surface tension. The characteristic flow rates for which the tapering menisci become unstable do not depend on the pressure drop applied to the system to produce the micro-jet. They increase (decrease) with viscosity for very low (high) viscosity liquids. Experiments confirmed the validity of the above conclusions. For each applied pressure drop, there is a minimum liquid flow rate below which the liquid meniscus drips. The minimum flow rates become practically independent of the applied pressure drop for sufficiently large values of this quantity. There exists an optimum value of the capillary-to-orifice distance for which the minimum flow rate attains a limiting value, which constitutes the lowest flow rate attainable with a given configuration in the steady jetting regime. A two-dimensional stability map with a high degree of validity is plotted on the plane defined by the Reynolds and capillary numbers based on the limiting flow rate.

  15. High flow ceramic pot filters.

    Science.gov (United States)

    van Halem, D; van der Laan, H; Soppe, A I A; Heijman, S G J

    2017-11-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6-19 L h-1), but initial LRVs for E. coli of high flow filters was slightly lower than for regular ceramic pot filters. This disadvantage was, however, only temporarily as the clogging in high flow filters had a positive effect on the LRV for E. coli (from below 1 to 2-3 after clogging). Therefore, it can be carefully concluded that regular ceramic pot filters perform better initially, but after clogging, the high flow filters have a higher flow rate as well as a higher LRV for E. coli. To improve the initial performance of new high flow filters, it is recommended to further utilize residence time of the water in the receptacle, since additional E. coli inactivation was observed during overnight storage. Although a relationship was observed between flow rate and LRV of MS2 bacteriophages, both regular and high flow filters were unable to reach over 2 LRV. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Ultrasonic rate measurement of multiphase flow

    Science.gov (United States)

    Dannert, David A.; Horne, Roland N.

    1993-01-01

    One of the most important tools in production logging and well testing is the downhole flowmeter. Unfortunately, existing tools are inaccurate outside of an idealized single phase flow regime. Spinner tools are inaccurate at extremely high or low flow rates and when the flow rate is variable. Radioactive tracer tools have similar inaccuracies and are extremely sensitive to the flow regime. Both tools completely fail in the presence of multiphase flow, whether for gas/oil, gas/water, or fluid/solid. Downhole flowmetering is important for locating producing zones and thief zones and monitoring production and injection rates. The effects of stimulation can also be determined. The goal of this project is the investigation of accurate downhole flowmetering techniques for all single phase flow regimes and multiphase flows. The measurement method investigated in this report is the use of ultrasound. There are two ways to use ultrasound for fluid velocity measurement. The first method, examined in Chapter 2, is the contrapropagation, or transit-time, method which compares travel times with and against fluid flow. Chapter 3 details the second method which measures the Doppler frequency shift of a reflected sound wave in the moving fluid. Both of these technologies need to be incorporated in order to build a true multiphase flowmeter. Chapter 4 describes the proposed downhole multiphase flowmeter.

  17. Effect of scanline orientation on ventricular flow propagation: assessment using high frame-rate color Doppler echocardiography

    Science.gov (United States)

    Greenberg, N. L.; Castro, P. L.; Drinko, J.; Garcia, M. J.; Thomas, J. D.

    2000-01-01

    Color M-mode echocardiography has recently been utilized to describe diastolic flow propagation velocity (Vp) in the left ventricle. While increasing temporal resolution from 15 to 200 Hz, this M-mode technique requires the user to select a single scanline, potentially limiting quantification of Vp due to the complex three-dimensional inflow pattern. We previously performed computational fluid dynamics simulations to demonstrate the insignificance of the scanline orientation, however geometric complexity was limited. The purpose of this study was to utilize high frame-rate 2D color Doppler images to investigate the importance of scanline selection in patients for the quantification of Vp. 2D color Doppler images were digitally acquired at 50 frames/s in 6 subjects from the apical 4-chamber window (System 5, GE/Vingmed, Milwaukee, WI). Vp was determined for a set of scanlines positioned through 5 locations across the mitral annulus (from the anterior to posterior mitral annulus). An analysis of variance was performed to examine the differences in Vp as a function of scanline position. Vp was not effected by scanline position in sampled locations from the center of the mitral valve towards the posterior annulus. Although not statistically significant, there was a trend to slower propagation velocities on the anterior side of the valve (60.8 +/- 16.7 vs. 54.4 +/- 13.6 cm/s). This study clinically validates our previous numerical experiment showing that Vp is insensitive to small perturbations of the scanline through the mitral valve. However, further investigation is necessary to examine the impact of ventricular geometry in pathologies including dilated cardiomyopathy.

  18. PERMCAT experiments with tritium at high helium flow rates relevant for the tritium extraction systems using the CAPER facility at TLK

    Energy Technology Data Exchange (ETDEWEB)

    Bükki-Deme, András, E-mail: andras.buekki-deme@kit.edu; Demange, David; Le, Thanh-Long; Fanghänel, Eleonore; Simon, Karl-Heinz

    2016-11-01

    Highlights: • We examined PERMCAT reactor efficiency processing tritiated water at high Helium carrier flow rates. • We have found that – as expected from previous studies – that the swamping ratio (ratio between the impurity and purge side flow rates) has a key effect on the decontamination factors. • On the other hand, some rather unexpected effects tend to show that the limiting phenomena of such specific operation of PERMCAT reactors (at high impurity flow rates, thus short residence time) lies on the kinetics of the isotope exchange reactions. - Abstract: Experiments are still necessary to consolidate the processes retained for the Tritium Extraction Systems of the European ITER Test Blanket Modules (TBM). A PERMCAT reactor combines a catalyst promoting isotope exchange reactions and a Pd/Ag membrane allowing tritium recovery from complex gaseous mixtures containing tritium in different chemical forms. Originally developed for the Tokamak Exhaust Processing, the PERMCAT process is also candidate to detritiate the water arising from an adsorption column installed in the TBM ancillary systems. We discuss the results of an extensive experimental campaign using a PERMCAT reactor to process Q{sub 2}O containing impurity gas mixtures at high flow rates. Two different experimental configurations were studied, namely PERMCAT stand-alone, and PERMCAT in combination with a zeolite molecular sieve bed (MSB, previously loaded with Q{sub 2}O) under regeneration. On the one hand, many expected behaviors were observed, such as the key influence of the swamping ratio (ratio between the impurity and purge side flow rates) on the decontamination factors. On the other hand, some rather unexpected effects tend to show that the limiting phenomena of such specific operation of PERMCAT reactors (at high flow rates, thus short residence time) lies on the kinetics of the isotope exchange reactions.

  19. Gas chromatography flow rates for determining deuterium/hydrogen ratios of natural gas by gas chromatography/high-temperature conversion/isotope ratio mass spectrometry.

    Science.gov (United States)

    Jia, Wanglu; Peng, Ping'an; Liu, Jinzhong

    2008-08-01

    The effects of the gas chromatography flow rate on the determination of the deuterium/hydrogen (D/H) ratios of natural gas utilising gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/TC/IRMS) have been evaluated. In general, the measured deltaD values of methane, ethane and propane decrease with increase in column flow rate. When the column flow rate is 1 mL/min or higher, which is commonly used for the determination of D/H ratios of natural gas, the organic H in gas compounds may not be completely converted into hydrogen gas. Based on the results of experiments conducted on a GC column with an i.d. of 0.32 mm, a GC flow rate of 0.6 mL/min is proposed for determining the D/H ratios of natural gas by GC/TC/IRMS. Although this value may be dependent on the instrument conditions used in this work, we believe that correct deltaD values of organic compounds with a few carbon atoms are obtained only when relatively low GC flow rates are used for D/H analysis by GC/TC/IRMS. Moreover, as the presence of trace water could significantly affect the determination of D/H ratios, a newly designed inlet liner was used to remove trace water contained in some gas samples. Copyright (c) 2008 John Wiley & Sons, Ltd.

  20. HANARO core channel flow-rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Heon Il; Chae, Hee Tae; Im, Don Soon; Kim, Seon Duk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-06-01

    HANARO core consists of 23 hexagonal flow tubes and 16 cylindrical flow tubes. To get the core flow distribution, we used 6 flow-rate measuring dummy fuel assemblies (instrumented dummy fuel assemblies). The differential pressures were measured and converted to flow-rates using the predetermined relationship between AP and flow-rate for each instrumented dummy fuel assemblies. The flow-rate for the cylindrical flow channels shows +-7% relative errors and that for the hexagonal flow channels shows +-3.5% relative errors. Generally the flow-rates of outer core channels show smaller values compared to those of inner core. The channels near to the core inlet pipe and outlet pipes also show somewhat lower flow-rates. For the lower flow channels, the thermal margin was checked by considering complete linear power histories. From the experimental results, the gap flow-rate was estimated to be 49.4 kg/s (cf. design flow of 50 kg/s). 15 tabs., 9 figs., 10 refs. (Author) .new.

  1. Coriolis mass flow rate meters for low flows

    NARCIS (Netherlands)

    Mehendale, A.

    2008-01-01

    The accurate and quick measurement of small mass flow rates (~10 mg/s) of fluids is considered an “enabling technology��? in semiconductor, fine-chemical, and food & drugs industries. Flowmeters based on the Coriolis effect offer the most direct sensing of the mass flow rate, and for this reason do

  2. Electromechanically Actuated Valve for Controlling Flow Rate

    Science.gov (United States)

    Patterson, Paul

    2007-01-01

    A proposed valve for controlling the rate of flow of a fluid would include an electric-motor-driven ball-screw mechanism for adjusting the seating element of the valve to any position between fully closed and fully open. The motor would be of a type that can be electronically controlled to rotate to a specified angular position and to rotate at a specified rate, and the ball screw would enable accurate linear positioning of the seating element as a function of angular position of the motor. Hence, the proposed valve would enable fine electronic control of the rate of flow and the rate of change of flow. The uniqueness of this valve lies in a high degree of integration of the actuation mechanism with the flow-control components into a single, relatively compact unit. A notable feature of this integration is that in addition to being a major part of the actuation mechanism, the ball screw would also be a flow-control component: the ball screw would be hollow so as to contain part of the main flow passage, and one end of the ball screw would be the main seating valve element. The relationships among the components of the valve are best understood by reference to the figure, which presents meridional cross sections of the valve in the fully closed and fully open positions. The motor would be supported by a bracket bolted to the valve body. By means of gears or pulleys and a timing belt, motor drive would be transmitted to a sleeve that would rotate on bearings in the valve body. A ball nut inside the sleeve would be made to rotate with the sleeve by use of a key. The ball screw would pass through and engage the ball nut. A key would prevent rotation of the ball screw in the valve body while allowing the ball screw to translate axially when driven by the ball nut. The outer surface of the ball screw would be threaded only in a mid-length region: the end regions of the outer surface of the ball screw would be polished so that they could act as dynamic sealing surfaces

  3. Tidal Modulation of Ice Flow on Kangerdlugssuaq and Helheim Glaciers, East Greenland, from High-Rate GPS Measurements

    DEFF Research Database (Denmark)

    Hamilton, G. S.; Stearns, L. A.; Elosegui, P.

    Boundary conditions at the frontal margins of tidewater glaciers provide important constraints on the balance of forces affecting ice flow and iceberg calving. For many large outlet glaciers in Greenland, the type of boundary condition (floating vs grounded ice) is not well known, owing to limited...

  4. Solids flow rate measurement in dense slurries

    Energy Technology Data Exchange (ETDEWEB)

    Porges, K.G.; Doss, E.D.

    1993-09-01

    Accurate and rapid flow rate measurement of solids in dense slurries remains an unsolved technical problem, with important industrial applications in chemical processing plants and long-distance solids conveyance. In a hostile two-phase medium, such a measurement calls for two independent parameter determinations, both by non-intrusive means. Typically, dense slurries tend to flow in laminar, non-Newtonian mode, eliminating most conventional means that usually rely on calibration (which becomes more difficult and costly for high pressure and temperature media). These issues are reviewed, and specific solutions are recommended in this report. Detailed calculations that lead to improved measuring device designs are presented for both bulk density and average velocity measurements. Cross-correlation, chosen here for the latter task, has long been too inaccurate for practical applications. The cause and the cure of this deficiency are discussed using theory-supported modeling. Fluid Mechanics are used to develop the velocity profiles of laminar non-Newtonian flow in a rectangular duct. This geometry uniquely allows the design of highly accurate `capacitive` devices and also lends itself to gamma transmission densitometry on an absolute basis. An absolute readout, though of less accuracy, is also available from a capacitive densitometer and a pair of capacitive sensors yields signals suitable for cross-correlation velocity measurement.

  5. NEW METHOD FOR ARRANGEMENT OF HIGH-ACCURATE DEVICES FOR MEASURING AND METERING LIQUID AND GAS FLOW RATE

    Directory of Open Access Journals (Sweden)

    I. E. Zuykov

    2009-01-01

    Full Text Available The paper presents results of a development and an industrial implementation of a new method for measuring liquid (water amount passing through measuring devices as a continuous flow by means of rotating blades. An algorithm of the device operation which serves as a basis for the method can be also used for designing devices for metering and control of gas consumption.The given method has its practical application in the electronic water meter developed at the «Elektronika» Plant of the RPC Integral.

  6. Flow rate measurements by means of tracers

    Energy Technology Data Exchange (ETDEWEB)

    Mosetti, F. (Trieste Univ. (Italy). Istituto di Geodesia e Geofisica)

    The application of some sources of diffusion for the flow rate measurement of water or other fluids is here presented. The laminar instantaneous source, obtained in practice with easy devices, is very useful in river or channel measurements. The analysis of the measurements could supply the flow rate and the presence of water losses or recharges. The section of the channel can also be determined by such a method.

  7. Purification of quinoline yellow components using high-speed counter-current chromatography by stepwise increasing the flow-rate of the mobile phase.

    Science.gov (United States)

    Oka, Hisao; Harada, Ken-Ichi; Suzuki, Masanao; Fujii, Kiyonaga; Iwaya, Masato; Ito, Yuko; Goto, Tomomi; Matsumoto, Hiroshi; Ito, Yoichiro

    2003-03-14

    Quinoline yellow (Color Index No. 47005) consists of multiple components that show a large difference in their partition coefficients (K), ranging from 0.03 to 3.3 in the solvent system tert.-butyl methyl ether (MTBE)-1-butanol-acetonitrile-aqueous 0.1 M trifluoroacetic acid (TFA). Consequently, it requires an excessively long elution time for the simultaneous separation of all components by the standard high-speed counter-current chromatography technique, which uses a constant flow-rate of the mobile phase. In order to overcome this problem, we increased the flow-rate of the mobile phase stepwise from 0.1 to 2.0 mL/min. Using this new procedure, six components (0.2-6.1 mg) were successfully isolated from 25 mg of a commercial quinoline yellow preparation in a single run using a two-phase solvent system composed of MTBE-1-butanol-acetonitrile-aqueous 0.1 M TFA (1:3:1:5, v/v). The purified components were analyzed by high-performance liquid chromatography, electrospray ionization mass spectrometry, and nuclear magnetic resonance spectroscopy.

  8. Optimum solar collector fluid flow rates

    DEFF Research Database (Denmark)

    Furbo, Simon; Shah, Louise Jivan

    1996-01-01

    Experiments showed that by means of a standard electronically controlled pump, type UPE 2000 from Grundfos it is possible to control the flow rate in a solar collector loop in such a way that the flow rate is strongly influenced by the temperature of the solar collector fluid passing the pump...... the energy consumption of a normal ciculation pump in the solar heating system.Calculations showed that the highest thermal performances for small SDHW systems based on mantle tanks with constant volume flow rates in the solar collector loops are achieved if the flow rate is situated in the interval from 0.......2 to 0.3 l/min. per m^2 solar collector for combi tank systems and in the interval from 0.3 to 0.4 l/min. per m^2 solar collector for preheating systems. Further, calculations showed that by means of an advanced control strategy for the flow rate - for instance if the flow rate is directly proportional...

  9. Visible-light active thin-film WO3 photocatalyst with controlled high-rate deposition by low-damage reactive-gas-flow sputtering

    Science.gov (United States)

    Oka, Nobuto; Murata, Akiyo; Nakamura, Shin-ichi; Jia, Junjun; Iwabuchi, Yoshinori; Kotsubo, Hidefumi; Shigesato, Yuzo

    2015-10-01

    A process based on reactive gas flow sputtering (GFS) for depositing visible-light active photocatalytic WO3 films at high deposition rates and with high film quality was successfully demonstrated. The deposition rate for this process was over 10 times higher than that achieved by the conventional sputtering process and the process was highly stable. Furthermore, Pt nanoparticle-loaded WO3 films deposited by the GFS process exhibited much higher photocatalytic activity than those deposited by conventional sputtering, where the photocatalytic activity was evaluated by the extent of decomposition of CH3CHO under visible light irradiation. The decomposition time for 60 ppm of CH3CHO was 7.5 times more rapid on the films deposited by the GFS process than on the films deposited by the conventional process. During GFS deposition, there are no high-energy particles bombarding the growing film surface, whereas the bombardment of the surface with high-energy particles is a key feature of conventional sputtering. Hence, the WO3 films deposited by GFS should be of higher quality, with fewer structural defects, which would lead to a decrease in the number of centers for electron-hole recombination and to the efficient use of photogenerated holes for the decomposition of CH3CHO.

  10. Visible-light active thin-film WO3 photocatalyst with controlled high-rate deposition by low-damage reactive-gas-flow sputtering

    Directory of Open Access Journals (Sweden)

    Nobuto Oka

    2015-10-01

    Full Text Available A process based on reactive gas flow sputtering (GFS for depositing visible-light active photocatalytic WO3 films at high deposition rates and with high film quality was successfully demonstrated. The deposition rate for this process was over 10 times higher than that achieved by the conventional sputtering process and the process was highly stable. Furthermore, Pt nanoparticle-loaded WO3 films deposited by the GFS process exhibited much higher photocatalytic activity than those deposited by conventional sputtering, where the photocatalytic activity was evaluated by the extent of decomposition of CH3CHO under visible light irradiation. The decomposition time for 60 ppm of CH3CHO was 7.5 times more rapid on the films deposited by the GFS process than on the films deposited by the conventional process. During GFS deposition, there are no high-energy particles bombarding the growing film surface, whereas the bombardment of the surface with high-energy particles is a key feature of conventional sputtering. Hence, the WO3 films deposited by GFS should be of higher quality, with fewer structural defects, which would lead to a decrease in the number of centers for electron-hole recombination and to the efficient use of photogenerated holes for the decomposition of CH3CHO.

  11. Vitreous flow rates through dual pneumatic cutters: effects of duty cycle and cut rate.

    Science.gov (United States)

    Abulon, Dina Joy K

    2015-01-01

    We aimed to investigate effects of instrument settings on porcine vitreous flow rates through dual pneumatic high-speed vitrectomy probes. The CONSTELLATION(®) Vision System was tested with 250, 450, and 650 mmHg of vacuum using six ULTRAVIT(®) vitrectomy probes of each diameter (25+(®), 25, 23, and 20 gauge) operated from 500 cuts per minute (cpm) up to 5,000 cpm. Duty cycle modes tested included biased open, 50/50, and biased closed. Flow rates were calculated by assessing the change in weight of porcine eyes during vitreous aspiration. Volumetric flow rate was measured with a computer-connected electronic scale. At lower cut rates, the biased open mode produced higher flow than did the 50/50 mode, which produced higher flow than did the biased closed mode. In the biased closed and 50/50 modes, vitreous flow rates tended to increase with increasing cut rate. Vitreous flow rates in the biased open duty cycle mode remained relatively constant across cut rates. Vitreous flow rates through dual pneumatic vitrectomy probes could be manipulated by changing the duty cycle modes on the vitrectomy system. Differences in duty cycle behavior suggest that high-speed cut rates of 5,000 cpm may optimize vitreous aspiration.

  12. Vitreous flow rates through dual pneumatic cutters: effects of duty cycle and cut rate

    Directory of Open Access Journals (Sweden)

    Abulon DJK

    2015-02-01

    Full Text Available Dina Joy K Abulon Medical Affairs, Alcon Research, Ltd, Lake Forest, CA, USA Purpose: We aimed to investigate effects of instrument settings on porcine vitreous flow rates through dual pneumatic high-speed vitrectomy probes. Methods: The CONSTELLATION® Vision System was tested with 250, 450, and 650 mmHg of vacuum using six ULTRAVIT® vitrectomy probes of each diameter (25+®, 25, 23, and 20 gauge operated from 500 cuts per minute (cpm up to 5,000 cpm. Duty cycle modes tested included biased open, 50/50, and biased closed. Flow rates were calculated by assessing the change in weight of porcine eyes during vitreous aspiration. Volumetric flow rate was measured with a computer-connected electronic scale. Results: At lower cut rates, the biased open mode produced higher flow than did the 50/50 mode, which produced higher flow than did the biased closed mode. In the biased closed and 50/50 modes, vitreous flow rates tended to increase with increasing cut rate. Vitreous flow rates in the biased open duty cycle mode remained relatively constant across cut rates. Conclusion: Vitreous flow rates through dual pneumatic vitrectomy probes could be manipulated by changing the duty cycle modes on the vitrectomy system. Differences in duty cycle behavior suggest that high-speed cut rates of 5,000 cpm may optimize vitreous aspiration. Keywords: enhanced 25-gauge vitrectomy, 25-gauge vitrectomy, 20-gauge vitrectomy, 23-gauge vitrectomy, aspiration, Constellation Vision System

  13. Flow rates for sharp-edged orifices

    Science.gov (United States)

    Groesbeck, W. A.; Manning, F. L.

    1975-01-01

    Two charts are proposed for calculating the flow coefficient and the area correction factor used in the equation for the flow rate through a sharp-edged orifice. The proposed charts account for variations in the discharge coefficient of sharp-edged orifices and can be used with any pressure ratio for both subcritical and supercritical flow conditions. They can also be used for any gas by using the appropriate gas constant and ratio of specific heats. The application of the charts is illustrated by examples.

  14. Exchange Flow Rate Measurement Technique in Density Different Gases

    Directory of Open Access Journals (Sweden)

    Motoo Fumizawa

    2012-04-01

    Full Text Available Buoyancy-driven exchange flows of helium-air through inclined a narrow tube was investigated. Exchange flows may occur following the opening of a window for ventilation, as well as when a pipe ruptures in a high temperature gas-cooled reactor. The experiment in this paper was carried out in a test chamber filled with helium and the flow was visualized using the smoke wire method. A high-speed camera recorded the flow behavior. The image of the flow was transferred to digital data, and the slow flow velocity, i.e. micro flow rate was measured by PIV software. Numerical simulation was carried out by the code of moving particle method with Lagrange method.

  15. Controlling a wide range of flow rates

    Science.gov (United States)

    Perkins, G. S.

    1979-01-01

    Servo-operated valve and two flowmeters allow accurate control over 1,900:1 flow-rate range. It was developed as part of laboratory instrument for measuring properties of confined fluids under conditions analogous to those encountered in deep drilling operations.

  16. New findings on the minimum flow rate in Flow Focusing

    Science.gov (United States)

    Bluth, Benjamin; Ganan-Calvo, Alfonso M.

    2006-11-01

    Recently published works on spatial-temporal instability analyses have dealt with flow-focused micro-jets. Those works have revealed that the minimum rate of fluid that can be focused is, in many cases, linked to an absolute/convective instability transition of the focused fluid micro-jet. Further to this, a series of very recent experiments indicate that the minimum flow rate may result very plausibly from the breakdown of a stability ``chain'', a link of it --and possibly not the weakest one- being the micro jet. The dripping-jetting transition curves in the Reynolds-Weber parametrical space show a conspicuous, consistent and interesting turning point. Whether this behaviour reflects a possible cross-over between the instability of the jet and that of the cusp-like meniscus is here discussed. Indeed, these new results are now set in perspective along with those recently published ones.

  17. Pricing and Unresponsive Flows Purging for Global Rate Enhancement

    Directory of Open Access Journals (Sweden)

    G. Abbas

    2010-01-01

    Full Text Available Pricing-based Active Queue Management (AQM, such as Random Exponential Marking (REM, outperforms other probabilistic counterpart techniques, like Random Early Detection (RED, in terms of both high utilization and negligible loss and delay. However, the pricing-based protocols do not take account of unresponsive flows that can significantly alter the subsequent rate allocation. This letter presents Purge (Pricing and Un-Responsive flows purging for Global rate Enhancement that extends the REM framework to regulate unresponsive flows. We show that Purge is effective at providing fairness and requires small memory and low-complexity operations.

  18. The Salivary IgA Flow Rate Is Increased by High Concentrations of Short-Chain Fatty Acids in the Cecum of Rats Ingesting Fructooligosaccharides

    Directory of Open Access Journals (Sweden)

    Yuko Yamamoto

    2016-08-01

    Full Text Available Salivary immunoglobulin A (IgA serves as a major effector in mucosal immunity by preventing submucosal invasion of pathogens. However, the mechanism by which consumption of fermentable fibers increases IgA in saliva was not fully elucidated. This study investigated the effects of fructooligosaccharides (FOS intake and time after feeding on IgA levels in the saliva and cecal digesta and on the concentration of short-chain fatty acids (SCFA in the cecum in rats. Five-week-old rats were fed a fiber-free diet or a diet with 50 g/kg FOS for zero, one, four, and eight weeks. Ingestion of FOS at one and eight weeks led to a higher IgA flow rate of saliva per weight of submandibular gland tissue (p < 0.05, which positively correlated with the concentration of SCFA in the cecal digesta (rs = 0.86, p = 0.0006, n = 12, but showed no correlation with the concentration of IgA in the cecal digesta (rs = 0.15, p = 0.3, n = 48. These results suggested that ingestion of FOS increased salivary IgA secretion through high levels of SCFA in the large intestine, which was produced by fermentation of FOS. Thus, continuously ingesting FOS for more than one week could increase secretion of salivary IgA.

  19. Evaluation of IOM personal sampler at different flow rates.

    Science.gov (United States)

    Zhou, Yue; Cheng, Yung-Sung

    2010-02-01

    The Institute of Occupational Medicine (IOM) personal sampler is usually operated at a flow rate of 2.0 L/min, the rate at which it was designed and calibrated, for sampling the inhalable mass fraction of airborne particles in occupational environments. In an environment of low aerosol concentrations only small amounts of material are collected, and that may not be sufficient for analysis. Recently, a new sampling pump with a flow rate up to 15 L/min became available for personal samplers, with the potential of operating at higher flow rates. The flow rate of a Leland Legacy sampling pump, which operates at high flow rates, was evaluated and calibrated, and its maximum flow was found to be 10.6 L/min. IOM samplers were placed on a mannequin, and sampling was conducted in a large aerosol wind tunnel at wind speeds of 0.56 and 2.22 m/s. Monodisperse aerosols of oleic acid tagged with sodium fluorescein in the size range of 2 to 100 microm were used in the test. The IOM samplers were operated at flow rates of 2.0 and 10.6 L/min. Results showed that the IOM samplers mounted in the front of the mannequin had a higher sampling efficiency than those mounted at the side and back, regardless of the wind speed and flow rate. For the wind speed of 0.56 m/s, the direction-averaged (the average value of all orientations facing the wind direction) sampling efficiency of the samplers operated at 2.0 L/min was slightly higher than that of 10.6 L/min. For the wind speed of 2.22 m/s, the sampling efficiencies at both flow rates were similar for particles flow rates follows the inhalable mass curve for particles in the size range of 2 to 20 microm. The test results indicate that the IOM sampler can be used at higher flow rates.

  20. Melt volume flow rate and melt flow rate of kenaf fibre reinforced Floreon/magnesium hydroxide biocomposites.

    Science.gov (United States)

    Lee, C H; Sapuan, S M; Lee, J H; Hassan, M R

    2016-01-01

    A study of the melt volume flow rate (MVR) and the melt flow rate (MFR) of kenaf fibre (KF) reinforced Floreon (FLO) and magnesium hydroxide (MH) biocomposites under different temperatures (160-180 °C) and weight loadings (2.16, 5, 10 kg) is presented in this paper. FLO has the lowest values of MFR and MVR. The increment of the melt flow properties (MVR and MFR) has been found for KF or MH insertion due to the hydrolytic degradation of the polylactic acid in FLO. Deterioration of the entanglement density at high temperature, shear thinning and wall slip velocity were the possible causes for the higher melt flow properties. Increasing the KF loadings caused the higher melt flow properties while the higher MH contents created stronger bonding for higher macromolecular chain flow resistance, hence lower melt flow properties were recorded. However, the complicated melt flow behaviour of the KF reinforced FLO/MH biocomposites was found in this study. The high probability of KF-KF and KF-MH collisions was expected and there were more collisions for higher fibre and filler loading causing lower melt flow properties.

  1. Peak expiratory flow rate and Pulse Pressure values during the ...

    African Journals Online (AJOL)

    This study assessed the peak expiratory flow rate and pulse pressure during the luteal and menstruation phases of the menstrual cycle. The peak expiratory flow rate and pulse pressure were measured using the Wright's Peak Flow Meter and Mercury Sphygmomanometer respectively. The peak expiratory flow rate and ...

  2. Wake flow characteristics at high wind speed

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge; Larsen, Torben J.; Larsen, Gunner Chr.

    2016-01-01

    Wake flow characteristic at high wind speeds is the main subject of this paper. Although the wake losses decrease at high wind speeds it has been found in a recent study that for multiple wake inflow the increase in loading due to wake effects are substantial even at wind speeds well above rated ...

  3. Responses of prawn to water flow rates

    Energy Technology Data Exchange (ETDEWEB)

    Vascotto, G.L.; Nilas, P.U.

    1987-05-28

    An aquarium study to determine the responses of postlarval macrobrachium rosenbergii to varying water changes was carried out. Six week old postlarvae were raised in glass aquaria receiving 0, 1.15, 7.2 and 14.4 water changes per day over a 12 week period. The treatments had significant influences on survival, biomass, and average size of the animals. Maximum survival and highest biomass were found in the 1.15 water turnover treatment; however, this treatment also produced the smallest average size animals. Early high mortalities were attributed to poor growing conditions in the high and low flow treatments, while later mortality appeared to be biomass dependent.

  4. Life history and past demography maintain genetic structure, outcrossing rate, contemporary pollen gene flow of an understory herb in a highly fragmented rainforest.

    Science.gov (United States)

    Suárez-Montes, Pilar; Chávez-Pesqueira, Mariana; Núñez-Farfán, Juan

    2016-01-01

    Theory predicts that habitat fragmentation, by reducing population size and increasing isolation among remnant populations, can alter their genetic diversity and structure. A cascade of effects is expected: genetic drift and inbreeding after a population bottleneck, changes in biotic interactions that may affect, as in the case of plants, pollen dynamics, mating system, reproductive success. The detection of the effects of contemporary habitat fragmentation on the genetic structure of populations are conditioned by the magnitude of change, given the few number of generations since the onset of fragmentation, especially for long-lived organisms. However, the present-day genetic structure of populations may bear the signature of past demography events. Here, we examine the effects of rainforest fragmentation on the genetic diversity, population structure, mating system (outcrossing rate), indirect gene flow and contemporary pollen dynamics in the understory herb Aphelandra aurantiaca. Also, we assessed its present-day genetic structure under different past demographic scenarios. Twelve populations of A. aurantiaca were sampled in large (4), medium (3), and small (5) forest fragments in the lowland tropical rainforest at Los Tuxtlas region. Variation at 11 microsatellite loci was assessed in 28-30 reproductive plants per population. In two medium- and two large-size fragments we estimated the density of reproductive plants, and the mating system by analyzing the progeny of different mother plants per population. Despite prevailing habitat fragmentation, populations of A. aurantiaca possess high genetic variation (He  = 0.61), weak genetic structure (Rst  = 0.037), and slight inbreeding in small fragments. Effective population sizes (Ne ) were large, but slightly lower in small fragments. Migrants derive mostly from large and medium size fragments. Gene dispersal is highly restricted but long distance gene dispersal events were detected. Aphelandra aurantiaca shows

  5. Life history and past demography maintain genetic structure, outcrossing rate, contemporary pollen gene flow of an understory herb in a highly fragmented rainforest

    Directory of Open Access Journals (Sweden)

    Pilar Suárez-Montes

    2016-12-01

    Full Text Available Introduction Theory predicts that habitat fragmentation, by reducing population size and increasing isolation among remnant populations, can alter their genetic diversity and structure. A cascade of effects is expected: genetic drift and inbreeding after a population bottleneck, changes in biotic interactions that may affect, as in the case of plants, pollen dynamics, mating system, reproductive success. The detection of the effects of contemporary habitat fragmentation on the genetic structure of populations are conditioned by the magnitude of change, given the few number of generations since the onset of fragmentation, especially for long-lived organisms. However, the present-day genetic structure of populations may bear the signature of past demography events. Here, we examine the effects of rainforest fragmentation on the genetic diversity, population structure, mating system (outcrossing rate, indirect gene flow and contemporary pollen dynamics in the understory herb Aphelandra aurantiaca. Also, we assessed its present-day genetic structure under different past demographic scenarios. Methods Twelve populations of A. aurantiaca were sampled in large (4, medium (3, and small (5 forest fragments in the lowland tropical rainforest at Los Tuxtlas region. Variation at 11 microsatellite loci was assessed in 28–30 reproductive plants per population. In two medium- and two large-size fragments we estimated the density of reproductive plants, and the mating system by analyzing the progeny of different mother plants per population. Results Despite prevailing habitat fragmentation, populations of A. aurantiaca possess high genetic variation (He = 0.61, weak genetic structure (Rst = 0.037, and slight inbreeding in small fragments. Effective population sizes (Ne were large, but slightly lower in small fragments. Migrants derive mostly from large and medium size fragments. Gene dispersal is highly restricted but long distance gene dispersal events

  6. Digital valve for high pressure high flow applications

    Science.gov (United States)

    Badescu, Mircea; Sherrit, Stewart; Lewis, Derek; Bao, Xiaoqi; Bar-Cohen, Yoseph; Hall, Jeffery L.

    2016-04-01

    To address the challenges, which are involved with the development of flow control valves that can meet high demand requirements such as high pressure, high flow rate, limited power and limited space, the authors have conceived a novel design configuration. This design consists of a digitalized flow control valve with multipath and multistage pressure reduction structures. Specifically, the valve is configured as a set of parallel flow paths from the inlet to the outlet. A choke valve controls the total flow rate by digitally opening different paths or different combination of the paths. Each path is controlled by a poppet cap valve basically operated in on-off states. The number of flow states is 2N where N is the number of flow paths. To avoid erosion from sand in the fluid and high speed flow, the seal area of the poppet cap valve is located at a distance from the flow inlet away from the high speed flow and the speed is controlled to stay below a predefined erosion safe limit. The path is a multistage structure composed of a set of serial nozzles-expansion chambers that equally distribute the total pressure drop to each stage. The pressure drop of each stage and, therefore, the flow speed at the nozzles and expansion chambers is controlled by the number of stages. The paths have relatively small cross section and could be relatively long for large number of stages and still fit in a strict annular space limit. The paper will present the design configuration, analysis and preliminary test results.

  7. Hypersonic Air Flow with Finite Rate Chemistry

    National Research Council Canada - National Science Library

    Boyd, Ian

    1997-01-01

    ... describe the effects of non-equilibrium flow chemistry, shock interaction, and turbulent mixing and combustion on the performance of vehicles and air breathing engines designed to fly in the hypersonic flow...

  8. High flow ceramic pot filters

    NARCIS (Netherlands)

    van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

    2017-01-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more

  9. Milk Flow Rates from bottle nipples used after hospital discharge.

    Science.gov (United States)

    Pados, Britt Frisk; Park, Jinhee; Thoyre, Suzanne M; Estrem, Hayley; Nix, W Brant

    To test the milk flow rates and variability in flow rates of bottle nipples used after hospital discharge. Twenty-six nipple types that represented 15 common brands as well as variety in price per nipple and store location sold (e.g., Babies R' Us, Walmart, Dollar Store) were chosen for testing. Ten of each nipple type (n = 260 total) were tested by measuring the amount of infant formula expressed in 1 minute using a breast pump. Mean milk flow rate (mL/min) and coefficient of variation (CV) were calculated. Flow rates of nipples within brand were compared statistically. Milk flow rates varied from 1.68 mL/min for the Avent Natural Newborn Flow to 85.34 mL/min for the Dr. Brown's Standard Y-cut. Variability between nipple types also varied widely, from .03 for the Dr. Brown's Standard Level 3 to .37 for MAM Nipple 1 Slow Flow. The extreme range of milk flow rates found may be significant for medically fragile infants being discharged home who are continuing to develop oral feeding skills. The name of the nipple does not provide clear information about the flow rate to guide parents in decision making. Variability in flow rates within nipples of the same type may complicate oral feeding for the medically fragile infant who may not be able to adapt easily to change in flow rates. Both flow rate and variability should be considered when guiding parents to a nipple choice.

  10. Higher flow rates improve heating during hyperthermic intraperitoneal chemoperfusion.

    Science.gov (United States)

    Furman, Matthew J; Picotte, Robert J; Wante, Mark J; Rajeshkumar, Barur R; Whalen, Giles F; Lambert, Laura A

    2014-12-01

    Heated intraperitoneal chemotherapy (HIPEC) kills cancer cells via thermal injury and improved chemotherapeutic cytotoxicity. We hypothesize that higher HIPEC flow rates improve peritoneal heating and HIPEC efficacy. (1) A HIPEC-model (30.8 L cooler with attached extracorporeal pump) was filled with 37°C water containing a suspended 1 L saline bag (SB) wrapped in a cooling sleeve, creating a constant heat sink. (2) HIPECs were performed in a swine model. Inflow, outflow, and peritoneal temperatures were monitored as flow rates varied. (3) Flow rates and temperatures during 20 HIPECs were reviewed. Higher flow rates decreased time required to increase water bath (WB) and SB temperature to 43°C. With a constant heat sink, the minimum flow rate required to reach 43°C in the WB was 1.75 L/min. Higher flow rates lead to greater temperature gradients between the WB and SB. In the swine model, the minimum flow rate required to reach 43°C outflow was 2.5-3.0 L/min. Higher flows led to more rapid heating of the peritoneum and greater peritoneal/outflow temperature gradients. Increased flow during clinical HIPEC suggested improved peritoneal heating with lower average visceral temperatures. There is a minimum flow rate required to reach goal temperature during HIPEC. Flow rate is an important variable in achieving and maintaining goal temperatures during HIPEC. © 2014 Wiley Periodicals, Inc.

  11. Effect of Flow Characteristics in the Downstream of Butterfly Valve on the Flow Rate Measurement using Venturi Tube

    Science.gov (United States)

    Yoon, Seok Ho; Lee, Jungho; Yu, Cheong Hwan; Park, San-Jin; Chung, Chang-Hwan

    2010-06-01

    For testing large-capacity pump, the accurate flow rate measurement is needed in the test loop. As a measuring method of flow rate, venturi tube is recommended due to its low pressure loss. However, upstream disturbance of loop component such as valve has an effect upon the accuracy of flow rate measurement. For controlling flow rate in case of high flow rate and large-scale piping system, butterfly-type valve is generally used due to its compactness. However, butterfly valve disturbs downstream flow by generating turbulence, cavities, or abrupt pressure change. In this study, the effect of downstream disturbance of butterfly valve on the flow rate measurement using venturi tube is investigated. Test loop consists of circulation pump, reservoir, butterfly valve, venturi tube, and reference flow meter. The test is conducted with regard to a different valve opening angle of butterfly valve. PIV system is used to visualize and analyze flow in the downstream region of butterfly valve. According to valve opening angle, the flow characteristics and the accuracy of flow rate measurement are investigated.

  12. Milk flow rates from bottle nipples used after hospital discharge

    Science.gov (United States)

    Pados, Britt Frisk; Park, Jinhee; Thoyre, Suzanne M.; Estrem, Hayley; Nix, W. Brant

    2016-01-01

    Purpose To test the milk flow rates and variability in flow rates of bottle nipples used after hospital discharge. Study Design and Methods Twenty-six nipple types that represented 15 common brands as well as variety in price per nipple and store location sold (e.g., Babies R’ Us, Walmart, Dollar Store) were chosen for testing. Ten of each nipple type (n=260 total) were tested by measuring the amount of infant formula expressed in one minute using a breast pump. Mean milk flow rate (mL/min) and coefficient of variation (CV) were calculated. Flow rates of nipples within brand were compared statistically. Results Milk flow rates varied from 1.68 mL/min for the Avent Natural Newborn Flow to 85.34 mL/min for the Dr. Brown’s Standard Y-cut. Variability between nipple types also varied widely, from .03 for the Dr. Brown’s Standard Level 3 to .37 for MAM Nipple 1 Slow Flow. Clinical Implications The extreme range of milk flow rates found may be significant for medically fragile infants being discharged home who are continuing to develop oral feeding skills. The name of the nipple does not provide clear information about the flow rate to guide parents in decision-making. Variability in flow rates within nipples of the same type may complicate oral feeding for the medically fragile infant who may not be able to adapt easily to change in flow rates. Both flow rate and variability should be considered when guiding parents to a nipple choice. PMID:27008466

  13. Ventilator gas flow rates affect inspiratory time and ventilator efficiency index in term lambs.

    Science.gov (United States)

    Bach, Katinka P; Kuschel, Carl A; Oliver, Mark H; Bloomfield, Frank H

    2009-01-01

    Despite increasing survival in the smallest preterm infants, the incidence of chronic lung disease has not decreased. Research into ventilatory strategies has concentrated on minimising barotrauma, volutrauma and atelectotrauma, but little attention has been paid to the role of bias gas flow rates and the potential for rheotrauma or shear stress injury. Ventilated preterm infants frequently receive relatively high gas flow rates. We hypothesised that altering bias gas flow rates would change the efficiency of ventilation and thereby affect ventilatory parameters. We tested this hypothesis using an artificial lung followed by ventilation of 8 term lambs. Between flows of 2 and 15 l/min, inflation time (Ti) in the artificial lung was inversely related to the bias gas flow rate. In the ventilated lambs, Ti was inversely related to flow rates up to 10 l/min, with no statistically significant effect at flow rates >10 l/min. There were no adverse effects on gas exchange or cardiovascular parameters until a flow rate of 3 l/min was used, when inadequate gas exchange occurred. Ti is inversely associated with the bias gas flow rate. Flow rates much lower than those used in many neonatal units seem to provide adequate ventilation. We suggest that the role of ventilator gas flow rates, which may potentially influence shear stress in ventilator-induced lung injury, merits further investigation. Copyright 2009 S. Karger AG, Basel.

  14. Thrombus Formation at High Shear Rates.

    Science.gov (United States)

    Casa, Lauren D C; Ku, David N

    2017-06-21

    The final common pathway in myocardial infarction and ischemic stroke is occlusion of blood flow from a thrombus forming under high shear rates in arteries. A high-shear thrombus forms rapidly and is distinct from the slow formation of coagulation that occurs in stagnant blood. Thrombosis at high shear rates depends primarily on the long protein von Willebrand factor (vWF) and platelets, with hemodynamics playing an important role in each stage of thrombus formation, including vWF binding, platelet adhesion, platelet activation, and rapid thrombus growth. The prediction of high-shear thrombosis is a major area of biofluid mechanics in which point-of-care testing and computational modeling are promising future directions for clinically relevant research. Further research in this area will enable identification of patients at high risk for arterial thrombosis, improve prevention and treatment based on shear-dependent biological mechanisms, and improve blood-contacting device design to reduce thrombosis risk.

  15. Bioelectrochemical enhancement of anaerobic methanogenesis for high organic load rate wastewater treatment in a up-flow anaerobic sludge blanket (UASB) reactor.

    Science.gov (United States)

    Zhao, Zhiqiang; Zhang, Yaobin; Chen, Shuo; Quan, Xie; Yu, Qilin

    2014-10-17

    A coupling process of anaerobic methanogenesis and electromethanogenesis was proposed to treat high organic load rate (OLR) wastewater. During the start-up stage, acetate removal efficiency of the electric-biological reactor (R1) reached the maximization about 19 percentage points higher than that of the control anaerobic reactor without electrodes (R2), and CH4 production rate of R1 also increased about 24.9% at the same time, while additional electric input was 1/1.17 of the extra obtained energy from methane. Coulombic efficiency and current recorded showed that anodic oxidation contributed a dominant part in degrading acetate when the metabolism of methanogens was low during the start-up stage. Along with prolonging operating time, aceticlastic methanogenesis gradually replaced anodic oxidation to become the main pathway of degrading acetate. When the methanogens were inhibited under the acidic conditions, anodic oxidation began to become the main pathway of acetate decomposition again, which ensured the reactor to maintain a stable performance. FISH analysis confirmed that the electric field imposed could enrich the H2/H(+)-utilizing methanogens around the cathode to help for reducing the acidity. This study demonstrated that an anaerobic digester with a pair of electrodes inserted to form a coupling system could enhance methanogenesis and reduce adverse impacts.

  16. Measuring Flow Rate in Crystalline Bedrock Wells Using the Dissolved Oxygen Alteration Method.

    Science.gov (United States)

    Vitale, Sarah A; Robbins, Gary A

    2017-07-01

    Determination of vertical flow rates in a fractured bedrock well can aid in planning and implementing hydraulic tests, water quality sampling, and improving interpretations of water quality data. Although flowmeters are highly accurate in flow rate measurement, the high cost and logistics may be limiting. In this study the dissolved oxygen alteration method (DOAM) is expanded upon as a low-cost alternative to determine vertical flow rates in crystalline bedrock wells. The method entails altering the dissolved oxygen content in the wellbore through bubbler aeration, and monitoring the vertical advective movement of the dissolved oxygen over time. Measurements were taken for upward and downward flows, and under ambient and pumping conditions. Vertical flow rates from 0.06 to 2.30 Lpm were measured. To validate the method, flow rates determined with the DOAM were compared to pump discharge rates and found to be in agreement within 2.5%. © 2017, National Ground Water Association.

  17. Peak Expiratory Flow Rate In Cigarette Smokers | Ukoli | Highland ...

    African Journals Online (AJOL)

    Objective: To compare lung function between smokers and non-smokers using Peak Expiratory Flow Rate (PEFR). Methods: This study examines the peak expiratory flow rate (PEFR) of three hundred and forty cigarette smokers, age and sex-matched with PEFR of equal number of non-smokers. Results: The mean PEFR of ...

  18. GROWTH RATE DISTRIBUTION OF BORAX SINGLE CRYSTALS ON THE (001 FACE UNDER VARIOUS FLOW RATES

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available The growth rates of borax single crystals from aqueous solutions at various flow rates in the (001 direction were measured using in situ cell method. From the growth rate data obtained, the growth rate distribution of borax crystals was investigated using Minitab Software and SPSS Software at relative supersaturation of 0807 and temperature of 25 °C. The result shows that normal, gamma, and log-normal distribution give a reasonably good fit to GRD. However, there is no correlation between growth rate distribution and flow rate of solution.   Keywords: growth rate dispersion (GRD, borax, flow rate

  19. Electro-flow focusing. The high conductivity, low viscosity limit

    Science.gov (United States)

    Ganan-Calvo, Alfonso M.; Lopez-Herrera, José M.

    2006-11-01

    Electro-flow focusing, a technique combining the features of electrospray (ES) and flow focusing (FF), provides a reliable tool to reach parametrical micro-jetting ranges not attainable by ES or FF alone under specific operational regimes (liquid properties and flow rate). In this work, we provide not only a closed theoretical model predicting the diameter of a high electrical conductivity electro-flow focused liquid micro-jet, but also its convective/absolute instability, linked to the jetting/dripping transition and the minimum liquid flow rate that can be issued in steady jetting regime. Our predictions are compared to experiments with good accord.

  20. Anomalous accumulation rates resulting from ice flow over Lake Vostok

    Science.gov (United States)

    Leonard, K. C.; Studinger, M.; Bell, R. E.; Tremblay, B.

    2004-12-01

    The accumulation rate of snow is crucial to the development of accurate age-depth models for ice-cores. The dating of the Vostok ice-core generally assumes that accumulation rates vary linearly between the core site and the ice divide 250 km to the west [Jouzel et al., 1996; Lorius et al., 1985; Petit et al., 1999], an assumption which impacts the timing of prominent climatic transitions. We present evidence for a local accumulation rate anomaly at the ice surface above the western shoreline of Lake Vostok. A significant thickening between isochronous layers results from this geographically fixed high accumulation zone which can be stratigraphically traced to a depth of 820-1100 m in the Vostok ice-core, a portion known for its high accumulation rates and paleoclimate records that deviate from other Antarctic ice-core records. This non-climatic accumulation anomaly in the Vostok ice-core impacts the flow dependent age models and subsequent interpretations of sequencing of global climate shifts during the last glacial. These previously unreported geographically fixed accumulation rate anomalies are introduced into ice-cores drilled away from ice domes (i.e., Byrd and Vostok) and should be considered in age depth models.

  1. High flow nasal cannula for respiratory support in preterm infants.

    LENUS (Irish Health Repository)

    Wilkinson, Dominic

    2011-01-01

    High flow nasal cannulae (HFNC) are small, thin, tapered cannulae used to deliver oxygen or blended oxygen and air at flow rates of > 1 L\\/min. HFNC can be used to provide high concentrations of oxygen and may deliver positive end-expiratory pressure.

  2. Increased flow resistance and decreased flow rate in patients with acute respiratory distress syndrome: The role of autonomic nervous modulation

    Directory of Open Access Journals (Sweden)

    I-Chen Chen

    2016-01-01

    Conclusion: The flow rate is decreased and the flow resistance increased in patients with ARDS. PEEP is one of the causes of increased flow resistance and decreased flow rate in patients with ARDS. Another cause of decreased flow rate and increased flow resistance in ARDS patients is the increased vagal activity and decreased sympathetic activity. The monitoring of flow rate and flow resistance during mechanical ventilation might be useful for the proper management of ARDS patients.

  3. Estimation of blood flow rates in large microvascular networks.

    Science.gov (United States)

    Fry, Brendan C; Lee, Jack; Smith, Nicolas P; Secomb, Timothy W

    2012-08-01

    Recent methods for imaging microvascular structures provide geometrical data on networks containing thousands of segments. Prediction of functional properties, such as solute transport, requires information on blood flow rates also, but experimental measurement of many individual flows is difficult. Here, a method is presented for estimating flow rates in a microvascular network based on incomplete information on the flows in the boundary segments that feed and drain the network. With incomplete boundary data, the equations governing blood flow form an underdetermined linear system. An algorithm was developed that uses independent information about the distribution of wall shear stresses and pressures in microvessels to resolve this indeterminacy, by minimizing the deviation of pressures and wall shear stresses from target values. The algorithm was tested using previously obtained experimental flow data from four microvascular networks in the rat mesentery. With two or three prescribed boundary conditions, predicted flows showed relatively small errors in most segments and fewer than 10% incorrect flow directions on average. The proposed method can be used to estimate flow rates in microvascular networks, based on incomplete boundary data, and provides a basis for deducing functional properties of microvessel networks. © 2012 John Wiley & Sons Ltd.

  4. Fluid/Vapor Separator for Variable Flow Rates

    Science.gov (United States)

    Lee, J. M.; Chuang, C.; Frederking, T. H.; Brown, G. S.; Kamioka, Y.; Vorreiter, J.

    1984-01-01

    Shutter varies gas throughput of porous plug. Variable area exposed on porous plug allows to pass varying rates of vapor flow while blocking flow of liquid helium II from cryogenic bath. Applications in refining operations, industrial chemistry, and steam-powered equipment.

  5. eaf tissue flows in ryegrass managed under different stocking rates

    Directory of Open Access Journals (Sweden)

    Mônique Foggiato da Silva

    2015-05-01

    Full Text Available Morphogenetic, structural variables and leaf biomass flows of Italian ryegrass (Lolium multiflorum Lam. were evaluated under two stocking rates: ‘Low’ and ‘High’. These rates were determined by heifers exclusively on pasture or on pasture and supplemented with corn grain. The experimental design was completely randomized following a repeated measure arrangement, two stocking rates, two and four replications of area for the stocking rates ‘low’ and ‘high’, respectively. The morphogenetic variables, the number of green leaves and tiller density were similar in both stocking rates. Leaf senescence rate was higher with low stocking rate. Heifers grazed with similar intensity and frequency in both stocking rates. The increase by 33.6% in the stocking rate caused by the use of supplement does not change the leaf biomass flow of Italian ryegrass, but alters its potential efficiency of use near the reproductive stage of the plant.

  6. variant formula for predicting peak expiratory flow rate in pregnant ...

    African Journals Online (AJOL)

    DR. AMINU

    Accepted: November, 2009. VARIANT FORMULA FOR PREDICTING PEAK EXPIRATORY FLOW RATE IN. PREGNANT WOMEN IN KURA LOCAL GOVERNMENT AREA, KANO STATE,. NIGERIA. A. I. Salisu. Department of Human Physiology, Faculty of Medicine, Bayero University, Kano salisahmedibrahim@yahoo.co.uk;.

  7. Design and Implementation of Automatic Air Flow Rate Control System

    Science.gov (United States)

    Akbar, A.; Saputra, C.; Munir, M. M.; Khairurrijal

    2016-08-01

    Venturimeter is an apparatus that can be used to measure the air flow rate. In this experiment we designed a venturimeter which equipped with a valve that is used to control the air flow rate. The difference of pressure between the cross sections was measured with the differential pressure sensor GA 100-015WD which can calculate the difference of pressures from 0 to 3737.33 Pa. A 42M048C Z36 stepper motor was used to control the valve. The precision of this motor rotation is about 0.15 °. A Graphical User Interface (GUI) was developed to monitor and set the value of flow rate then an 8-bit microcontroller was used to process the control system In this experiment- the venturimeter has been examined to get the optimal parameter of controller. The results show that the controller can set the stable output air flow rate.

  8. Flow rates through intravenous access devices: an in vitro study.

    Science.gov (United States)

    Khoyratty, Saleem I; Gajendragadkar, Pushpaj R; Polisetty, Kiran; Ward, Sue; Skinner, Tim; Gajendragadkar, Parag R

    2016-06-01

    Fluid administration using intravenous (IV) access devices is required in many settings. There are a lack of quantitative data comparing traditional cannulas and modern access devices. We aimed to investigate flow rates through modern intravenous access devices using an in vitro system. This is an experimental study. Rates of flow of intravenous fluids (crystalloid and colloid) were measured through various access devices using a uroflowmeter. Standardized conditions and repeat measurements ensured validity. Fluid was administered with or without the addition of a pressure bag and needle-free valve. Increasing the size of cannulas improved flow. Fourteen-gauge cannulas had significantly higher mean flow rates compared to 14G central venous lines in all conditions (136% higher with no pressure bag/valve; 95% CI, +130% to +152%; P Flow rates in IV devices can be maximized by pressure bag use and removal of needle-free valves. The rapid infusion catheter and emergency infusion catheter allow some increase in flow over a 14G cannula. Familiarity with varying flow rates across IV access devices could better inform clinical decisions. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  9. High Resolution, High Frame Rate Video Technology

    Science.gov (United States)

    1990-01-01

    Papers and working group summaries presented at the High Resolution, High Frame Rate Video (HHV) Workshop are compiled. HHV system is intended for future use on the Space Shuttle and Space Station Freedom. The Workshop was held for the dual purpose of: (1) allowing potential scientific users to assess the utility of the proposed system for monitoring microgravity science experiments; and (2) letting technical experts from industry recommend improvements to the proposed near-term HHV system. The following topics are covered: (1) State of the art in the video system performance; (2) Development plan for the HHV system; (3) Advanced technology for image gathering, coding, and processing; (4) Data compression applied to HHV; (5) Data transmission networks; and (6) Results of the users' requirements survey conducted by NASA.

  10. Blood flow rate measurements with indicator techniques revisited

    DEFF Research Database (Denmark)

    Sejrsen, Per; Bülow, Jens

    2009-01-01

    In view of the emerging role, disturbances in regional blood flow rate seem to play in the pathogenesis of the metabolic syndrome; we review the concepts of the classical indicator dilution and washout techniques used for determinations of regional blood flow rate. Prerequisites, assumptions......, necessary precautions for the application of these experimental techniques are emphasized. Special attention has been carried out to elucidate the consequence of a choice of indicators having a large distribution volume in the tissues....

  11. Investigation of Ultrasound-Measured Flow Velocity, Flow Rate and Wall Shear Rate in Radial and Ulnar Arteries Using Simulation.

    Science.gov (United States)

    Zhou, Xiaowei; Xia, Chunming; Stephen, Gandy; Khan, Faisel; Corner, George A; Hoskins, Peter R; Huang, Zhihong

    2017-05-01

    Parameters of blood flow measured by ultrasound in radial and ulnar arteries, such as flow velocity, flow rate and wall shear rate, are widely used in clinical practice and clinical research. Investigation of these measurements is useful for evaluating accuracy and providing knowledge of error sources. A method for simulating the spectral Doppler ultrasound measurement process was developed with computational fluid dynamics providing flow-field data. Specific scanning factors were adjusted to investigate their influence on estimation of the maximum velocity waveform, and flow rate and wall shear rate were derived using the Womersley equation. The overestimation in maximum velocity increases greatly (peak systolic from about 10% to 30%, time-averaged from about 30% to 50%) when the beam-vessel angle is changed from 30° to 70°. The Womersley equation was able to estimate flow rate in both arteries with less than 3% error, but performed better in the radial artery (2.3% overestimation) than the ulnar artery (15.4% underestimation) in estimating wall shear rate. It is concluded that measurements of flow parameters in the radial and ulnar arteries with clinical ultrasound scanners are prone to clinically significant errors. Copyright © 2017. Published by Elsevier Inc.

  12. Ultrasonic 3-D Vector Flow Method for Quantitative In Vivo Peak Velocity and Flow Rate Estimation.

    Science.gov (United States)

    Holbek, Simon; Ewertsen, Caroline; Bouzari, Hamed; Pihl, Michael Johannes; Hansen, Kristoffer Lindskov; Stuart, Matthias Bo; Thomsen, Carsten; Nielsen, Michael Bachmann; Jensen, Jorgen Arendt

    2017-03-01

    Current clinical ultrasound (US) systems are limited to show blood flow movement in either 1-D or 2-D. In this paper, a method for estimating 3-D vector velocities in a plane using the transverse oscillation method, a 32×32 element matrix array, and the experimental US scanner SARUS is presented. The aim of this paper is to estimate precise flow rates and peak velocities derived from 3-D vector flow estimates. The emission sequence provides 3-D vector flow estimates at up to 1.145 frames/s in a plane, and was used to estimate 3-D vector flow in a cross-sectional image plane. The method is validated in two phantom studies, where flow rates are measured in a flow-rig, providing a constant parabolic flow, and in a straight-vessel phantom ( ∅=8 mm) connected to a flow pump capable of generating time varying waveforms. Flow rates are estimated to be 82.1 ± 2.8 L/min in the flow-rig compared with the expected 79.8 L/min, and to 2.68 ± 0.04 mL/stroke in the pulsating environment compared with the expected 2.57 ± 0.08 mL/stroke. Flow rates estimated in the common carotid artery of a healthy volunteer are compared with magnetic resonance imaging (MRI) measured flow rates using a 1-D through-plane velocity sequence. Mean flow rates were 333 ± 31 mL/min for the presented method and 346 ± 2 mL/min for the MRI measurements.

  13. Unsteady Flows Control Hydrologic Turnover Rates in Antarctic Hyporheic Zones

    Science.gov (United States)

    Wlostowski, A. N.; Gooseff, M. N.; McKnight, D. M.; Lyons, W. B.; Saelens, E.

    2016-12-01

    channel. However, after only 2 days of high flows, the HZ becomes isotopically similar to the open channel. These results indicate that daily flood events control rates of hydrologic turnover and that complete flushing of the HZ can occur in less than 48 hours.

  14. Numerical study on flow rate limitation of open capillary channel flow through a wedge

    Directory of Open Access Journals (Sweden)

    Ting-Ting Zhang

    2016-04-01

    Full Text Available The flow characteristics of slender-column flow in wedge-shaped channel under microgravity condition are investigated in this work. The one-dimensional theoretical model is applied to predict the critical flow rate and surface contour of stable flow. However, the one-dimensional model overestimates the critical flow rate for not considering the extra pressure loss. Then, we develop a three-dimensional simulation method with OpenFOAM, a computational fluid dynamics tool, to simulate various phenomena in wedge channels with different lengths. The numerical results are verified with the capillary channel flow experimental data on the International Space Station. We find that the three-dimensional simulation perfectly predicts the critical flow rates and surface contours under various flow conditions. Meanwhile, the general behaviors in subcritical, critical, and supercritical flow are studied in three-dimensional simulation considering variations of flow rate and open channel length. The numerical techniques for three-dimensional simulation is validated for a wide range of configurations and is hopeful to provide valuable guidance for capillary channel flow experiment and efficient liquid management in space.

  15. Variability of cutaneous lymphatic flow rates in melanoma patients.

    Science.gov (United States)

    Uren, R F; Howman-Giles, R B; Thompson, J F; Roberts, J; Bernard, E

    1998-06-01

    Preoperative lymphoscintigraphy was performed in 198 consecutive patients with cutaneous melanoma prior to their definitive surgical treatment. After intradermal injection of antimony sulphide colloid labelled with technetium-99m, lymphatic flow rates were measured in each patient and found to vary according to the location of the primary tumour. The fastest flow rates occurred from melanoma sites on the distal limbs, particularly the lower limbs. The slowest flow rates were from the head and neck region and the proximal limbs, especially the upper arms and shoulders. Lack of flow in the early dynamic images occurred most commonly for tumours on the upper arms and shoulders. These results can be used to optimize the timing of blue dye injection prior to surgery and may influence the sentinel node biopsy method to be used in individuals who show no early drainage.

  16. Does Ramadan fasting affect expiratory flow rates in healthy subjects?

    Science.gov (United States)

    Subhan, Mirza M F; Siddiqui, Qamar A; Khan, Mohammed N; Sabir, Salman

    2006-11-01

    To assess whether Ramadan fasting affects the expiratory flow rates in healthy subjects, and to know if these effects correlate to a change in other variables. This unmatched case-control longitudinal study includes 46 non-smoking healthy subjects who undertook lung function testing at the Aga Khan University, Pakistan. Expiratory flow rates and body mass were measured in 3 Islamic months, corresponding to November 2001 to January 2002. There was a significant reduction in body mass in Ramadan compared to pre and post Ramadan. No significant changes in expiratory flows were seen during Ramadan as compared to the pre Ramadan period. However, forced expiratory flow rates at 75% of vital capacity (FEF(75)) and between 75% and 85% of vital capacity (FEF(75-85)) showed a significant increase in the post Ramadan period compared to Ramadan. Changes in FEF(75) were negatively correlated to changes in body mass between Ramadan and post Ramadan. This study shows that Ramadan fasting will not affect expiratory flow rates in healthy subjects. Post Ramadan values did show an increase in FEF(75) and FEF(75-85), possibly due to changes in body water and fat content. The reductions in body mass were most probably due to lack of nutrition and not dehydration as the fasts were performed in winter. Collection of reference values or early phase clinical trials measuring expiratory flow rates should not be affected by Ramadan fasting.

  17. Influence of Gas Flow Rate on the Deposition Rate on Stainless Steel 202 Substrates

    Directory of Open Access Journals (Sweden)

    M.A. Chowdhury

    2012-12-01

    Full Text Available Solid thin films have been deposited on stainless steel 202 (SS 202 substrates at different flow rates of natural gas using a hot filament thermal chemical vapor deposition (CVD reactor. In the experiments, the variations of thin film deposition rate with the variation of gas flow rate have been investigated. The effects of gap between activation heater and substrate on the deposition rate have also been observed. Results show that deposition rate on SS 202 increases with the increase in gas flow rate within the observed range. It is also found that deposition rate increases with the decrease in gap between activation heater and substrate. In addition, friction coefficient and wear rate of SS 202 sliding against SS 304 under different sliding velocities are also investigated before and after deposition. The experimental results reveal that improved friction coefficient and wear rate is obtained after deposition than that of before deposition.

  18. Penetrometry and estimation of the flow rate of powder excipients.

    Science.gov (United States)

    Zatloukal, Z; Sklubalová, Z

    2007-03-01

    In this work, penetrometry with a sphere was employed to study the flow properties of non-consolidated pharmaceutical powder excipients: sodium chloride, sodium citrate, boric acid, and sorbitol. In order to estimate flow rate, the pressure of penetration in Pascals was used. Penetrometry measurement with a sphere requires modification of the measurement container, in particular by decreasing the diameter of the container, to prevent undesirable movement of material in a direction opposite to that in which the sphere penetrates. Thus penetrometry by a sphere seems to be similar to indentation by the Brinell hardness tester. The pressure of penetration was determined from the depth of penetration by analogy with the Brinell hardness number and an equation for the inter conversion of the two variables is presented. The penetration pressure allowed direct estimation of the flow rate only for those powder excipients with a size fraction in the range of 0.250-0.630 mm. Using the ratio of penetration pressure to bulk density, a polynomial quadratic equation was generated from which the flow rates for the group of all tested powders could be estimated. Finally, if the inverse ratio of bulk density and penetration pressure was used as an independent variable, the flow rate could be estimated by linear regression with the coefficient of determination r2 = 0.9941. In conclusion, using sphere penetrometry, the flow properties of non-consolidated powder samples could be investigated by indentation. As a result, a linear regression in which the flow rate was directly proportional to the powder bulk density and inversely proportional to the penetration pressure could be best recommended for the estimation of the flow rate of powder excipients.

  19. Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse ...

    African Journals Online (AJOL)

    Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse Rate Following Ingestion of Increased Coffee Concentrations in Healthy Male Adults. ... It further indicates that, mild doses of coffee confer benefits on airflow in the lungs. While higher doses are also beneficial in improving airflow in the airway, such doses ...

  20. Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse ...

    African Journals Online (AJOL)

    We studied the effect of different concentrations of coffee on peak expiratory flow rate (PEFR), blood pressure and pulse rate in an attempt to determine some physiological effects of coffee intake. 18 apparently healthy adult males, age range 20 to 30 years, were recruited for the study over a three day period. Varying ...

  1. Homogenization of High-Contrast Brinkman Flows

    KAUST Repository

    Brown, Donald L.

    2015-04-16

    Modeling porous flow in complex media is a challenging problem. Not only is the problem inherently multiscale but, due to high contrast in permeability values, flow velocities may differ greatly throughout the medium. To avoid complicated interface conditions, the Brinkman model is often used for such flows [O. Iliev, R. Lazarov, and J. Willems, Multiscale Model. Simul., 9 (2011), pp. 1350--1372]. Instead of permeability variations and contrast being contained in the geometric media structure, this information is contained in a highly varying and high-contrast coefficient. In this work, we present two main contributions. First, we develop a novel homogenization procedure for the high-contrast Brinkman equations by constructing correctors and carefully estimating the residuals. Understanding the relationship between scales and contrast values is critical to obtaining useful estimates. Therefore, standard convergence-based homogenization techniques [G. A. Chechkin, A. L. Piatniski, and A. S. Shamev, Homogenization: Methods and Applications, Transl. Math. Monogr. 234, American Mathematical Society, Providence, RI, 2007, G. Allaire, SIAM J. Math. Anal., 23 (1992), pp. 1482--1518], although a powerful tool, are not applicable here. Our second point is that the Brinkman equations, in certain scaling regimes, are invariant under homogenization. Unlike in the case of Stokes-to-Darcy homogenization [D. Brown, P. Popov, and Y. Efendiev, GEM Int. J. Geomath., 2 (2011), pp. 281--305, E. Marusic-Paloka and A. Mikelic, Boll. Un. Mat. Ital. A (7), 10 (1996), pp. 661--671], the results presented here under certain velocity regimes yield a Brinkman-to-Brinkman upscaling that allows using a single software platform to compute on both microscales and macroscales. In this paper, we discuss the homogenized Brinkman equations. We derive auxiliary cell problems to build correctors and calculate effective coefficients for certain velocity regimes. Due to the boundary effects, we construct

  2. Influence of Reduced Mass Flow Rate and Chamber Backpressure on Swirl Injector Fluid Mechanics

    Science.gov (United States)

    Kenny, R Jeremy; Hulka, James R.

    2008-01-01

    Industry interest in variable-thrust liquid rocket engines places a demand on engine injector technology to operate over a wide range of liquid mass flow rates and chamber backpressures. One injection technology of current interest for variable thrust applications is an injector design with swirled fluids. Current swirl injector design methodologies do not take into account how swirl injector design parameters respond to elevated chamber backpressures at less than design mass flow rates. The current work was created to improve state-of-the-art swirl injector design methods in this area. The specific objective was to study the effects of elevated chamber backpressure and off-design mass flow rates on swirl injector fluid mechanics. Using a backpressure chamber with optical access, water was flowed through a swirl injector at various combinations of chamber backpressure and mass flow rates. The film thickness profile down the swirl injector nozzle section was measured through a transparent nozzle section of the injector. High speed video showed measurable increases in the film thickness profile with application of chamber backpressure and mass flow rates less than design. At prescribed combinations of chamber backpressure and injected mass flow rate, a discrete change in the film thickness profile was observed. Measured injector discharge coefficient values showed different trends with increasing chamber backpressure at low mass flow rates as opposed to near-design mass flow rates. Downstream spray angles showed classic changes in morphology as the mass flow rate was decreased below the design value. Increasing chamber backpressure decreased the spray angle at any injection mass flow rate. Experimental measurements and discussion of these results are reported in this paper.

  3. Estimation of Saturation Flow Rates at Signalized Intersections

    Directory of Open Access Journals (Sweden)

    Chang-qiao Shao

    2012-01-01

    Full Text Available The saturation flow rate is a fundamental parameter to measure the intersection capacity and time the traffic signals. However, it is revealed that traditional methods which are mainly developed using the average value of observed queue discharge headways to estimate the saturation headway might lead to underestimate saturation flow rate. The goal of this paper is to study the stochastic nature of queue discharge headways and to develop a more accurate estimate method for saturation headway and saturation flow rate. Based on the surveyed data, the characteristics of queue discharge headways and the estimation method of saturated flow rate are studied. It is found that the average value of queue discharge headways is greater than the median value and that the skewness of the headways is positive. Normal distribution tests were conducted before and after a log transformation of the headways. The goodness-of-fit test showed that for some surveyed sites, the queue discharge headways can be fitted by the normal distribution and for other surveyed sites, the headways can be fitted by lognormal distribution. According to the queue discharge headway characteristics, the median value of queue discharge headways is suggested to estimate the saturation headway and a new method of estimation saturation flow rates is developed.

  4. A MEMS-Based Flow Rate and Flow Direction Sensing Platform with Integrated Temperature Compensation Scheme

    Directory of Open Access Journals (Sweden)

    Chia-Yen Lee

    2009-07-01

    Full Text Available This study develops a MEMS-based low-cost sensing platform for sensing gas flow rate and flow direction comprising four silicon nitride cantilever beams arranged in a cross-form configuration, a circular hot-wire flow meter suspended on a silicon nitride membrane, and an integrated resistive temperature detector (RTD. In the proposed device, the flow rate is inversely derived from the change in the resistance signal of the flow meter when exposed to the sensed air stream. To compensate for the effects of the ambient temperature on the accuracy of the flow rate measurements, the output signal from the flow meter is compensated using the resistance signal generated by the RTD. As air travels over the surface of the cross-form cantilever structure, the upstream cantilevers are deflected in the downward direction, while the downstream cantilevers are deflected in the upward direction. The deflection of the cantilever beams causes a corresponding change in the resistive signals of the piezoresistors patterned on their upper surfaces. The amount by which each beam deflects depends on both the flow rate and the orientation of the beam relative to the direction of the gas flow. Thus, following an appropriate compensation by the temperature-corrected flow rate, the gas flow direction can be determined through a suitable manipulation of the output signals of the four piezoresistors. The experimental results have confirmed that the resulting variation in the output signals of the integrated sensors can be used to determine not only the ambient temperature and the velocity of the air flow, but also its direction relative to the sensor with an accuracy of ± 7.5o error.

  5. Doppler-Based Flow Rate Sensing in Microfluidic Channels

    Directory of Open Access Journals (Sweden)

    Liron Stern

    2014-09-01

    Full Text Available We design, fabricate and experimentally demonstrate a novel generic method to detect flow rates and precise changes of flow velocity in microfluidic devices. Using our method we can measure flow rates of ~2 mm/s with a resolution of 0.08 mm/s. The operation principle is based on the Doppler shifting of light diffracted from a self-generated periodic array of bubbles within the channel and using self-heterodyne detection to analyze the diffracted light. As such, the device is appealing for variety of “lab on chip” bio-applications where a simple and accurate speed measurement is needed, e.g., for flow-cytometry and cell sorting.

  6. High Flow Nasal Cannulae in preterm infants

    Directory of Open Access Journals (Sweden)

    F. Ciuffini

    2013-06-01

    Full Text Available Despite of improved survival of premature infants, the incidence of long term pulmonary complications, mostly associated with ventilation-induced lung injury, remains high. Non invasive ventilation (NIV is able to reduce the adverse effects of mechanical ventilation. Although nasal continuous positive airway pressure (NCPAP is an effective mode of NIV, traumatic nasal complications and intolerance of the nasal interface are common. Recently high flow nasal cannula (HFNC is emerging as an efficient, better tolerated form of NIV, allowing better access to the baby’s face, which may improve nursing, feeding and bonding. The aim of this review is to discuss the available evidence of effectiveness and safety of HFNC in preterm newborns with respiratory distress syndrome (RDS. It is known that distending pressure generated by HFNC increases with increasing flow rate and decreasing infant size and varies according to the amount of leaks by nose and mouth. The effects of HFNC on lung mechanics, its clinical efficacy and safety are still insufficiently investigated. In conclusion, there is a growing evidence of the feasibility of HFNC as an alternative mode of NIV. However, further larger randomized trials are required, before being able to recommend HFNC in the treatment of moderate respiratory distress of preterm infants.

  7. A novel concept of measuring mass flow rates using flow induced ...

    Indian Academy of Sciences (India)

    1555–1566. c Indian Academy of Sciences. A novel concept of measuring mass flow rates using flow induced stresses. P I JAGAD1,∗, B P PURANIK2 and A W DATE2. 1Department of Mechanical Engineering, Sinhgad College of Engineering,. Vadgaon (Bk), Pune 411 041, India. 2Department of Mechanical Engineering, ...

  8. Efficiencies of flat plate solar collectors at different flow rates

    DEFF Research Database (Denmark)

    Chen, Ziqian; Furbo, Simon; Perers, Bengt

    2012-01-01

    Two flat plate solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one collector is equipped with an ETFE foil between...... the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rate are obtained. The calculated efficiencies are in good agreement...

  9. Stretching of red blood cells at high strain rates

    Science.gov (United States)

    Mancuso, J. E.; Ristenpart, W. D.

    2017-10-01

    Most work on the mechanical behavior of red blood cells (RBCs) in flow has focused on simple shear flows. Relatively little work has examined RBC deformations in the physiologically important extensional flow that occurs at the entrance to a constriction. In particular, previous work suggests that RBCs rapidly stretch out and then retract upon entering the constriction, but to date no model predicts this behavior for the extremely high strain rates typically experienced there. In this Rapid Communication, we use high speed video to perform systematic measurements of the dynamic stretching behavior of RBCs as they enter a microfluidic constriction. We demonstrate that both the Kelvin-Voigt and Skalak viscoelastic models capture the observed stretching dynamics, up to strain rates as high as 2000 s-1. The results indicate that the effective elastic modulus of the RBC membrane at these strain rates is an order of magnitude larger than moduli measured by micropipette aspiration or other low strain rate techniques.

  10. Ultrasonic Enrichment of Flowing Blood Cells in Capillars: Influence of the Flow Rate

    Science.gov (United States)

    Carreras, Pilar; Gonzalez, Itziar; Ahumada, Oscar

    Red blood cells subjected to standing waves collect at the pressure nodes during their flow motion. Blood is a non-newtonian fluid whose density and other properties are defined by its flow velocity. Their drift motion is governed by the radiation force together with hydrodynamic conditions. This work presents a study of the blood cell enrichment performed in a rectangular capillar at f=1 MHz as a function of their flow motion. The cells collect along the central axis of the capillary in very few seconds, with a clearance in other lateral areas. Optimal flow rates below 100uL/min were found in the experiments.

  11. Flow rate and flow equation of pharmaceutical free-flowable powder excipients.

    Science.gov (United States)

    Sklubalová, Zdenka; Zatloukal, Zdenek

    2013-02-01

    Basic aspect of powder handling is powder flow which depends on mechanical properties of the solid material. This experimental work presents the results of flowability testing of the free-flowable particle size fraction of 0.0250-0.0315 cm of five powder excipients. The single-point determination of the mass flow rate from a cylindrical, flat-bottomed hopper was primarily influenced by the diameter of a circular orifice. The significant effect of the orifice height was also noted. Increasing the orifice height, the flow under gravity is directed resulting in the sudden acceleration of the flow rate. The critical zone relates to the orifice diameter. The multi-point determination of flowability employed the actual parameters of the flow equation which allows the prediction of the mass flow rate. The precision of the prediction was the basic criterion in optimization of the orifice geometry. Based on the results, the orifice height of 1.6 cm can be recommended for the correction of faster powder flow. For the slower powder flow, an orifice height of 0.2 cm can be used alternatively. In conclusion, the information about the orifice height used should be referred to whenever test the powder flowability and compare the results.

  12. A model for reaction rates in turbulent reacting flows

    Science.gov (United States)

    Chinitz, W.; Evans, J. S.

    1984-01-01

    To account for the turbulent temperature and species-concentration fluctuations, a model is presented on the effects of chemical reaction rates in computer analyses of turbulent reacting flows. The model results in two parameters which multiply the terms in the reaction-rate equations. For these two parameters, graphs are presented as functions of the mean values and intensity of the turbulent fluctuations of the temperature and species concentrations. These graphs will facilitate incorporation of the model into existing computer programs which describe turbulent reacting flows. When the model was used in a two-dimensional parabolic-flow computer code to predict the behavior of an experimental, supersonic hydrogen jet burning in air, some improvement in agreement with the experimental data was obtained in the far field in the region near the jet centerline. Recommendations are included for further improvement of the model and for additional comparisons with experimental data.

  13. High frame rate synthetic aperture duplex imaging

    DEFF Research Database (Denmark)

    Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Pihl, Michael Johannes

    2013-01-01

    Conventional color flow images are limited in velocity range and can either show the high velocities in systole or be optimized for the lower diastolic velocities. The full dynamics of the flow is, thus, hard to visualize. The dynamic range can be significantly increased by employing synthetic ap...

  14. Peak Expiratory Flow Rate in Petroleum Depot Workers and Petrol ...

    African Journals Online (AJOL)

    Peak Expiratory Flow Rate (PEFR) values in litres per minute were determined in petrol depot loaders, petrol station attendants and in control subjects. The PEFR values were 315 ± 94, 386 + 91 and 529 + 94 litres/min. in depot workers, petrol attendants and control subjects respectively. The value in the control subjects ...

  15. Peak expiratory flow rate and respiratory symptoms following ...

    African Journals Online (AJOL)

    Peak expiratory flow rate (PEFR) of 350 rural women aged (20-70 years) in Edo State, Nigeria who actively used wood as a source of fuel for cooking was measured. The height, chest circumference, weight and blood pressure of the women were also measured. Respiratory symptoms of cough with sputum production, ...

  16. variations of peak expiratory flow rate with anthropometric

    African Journals Online (AJOL)

    admin

    Summary: PEFR was measured in 300 healthy adult male and female staff and students of the. University of Benin, Benin City, and the College of Education, Ekiadolor, near Benin. The variations of. Peak Expiratory Flow Rate (PEFR) with respect to height (ht), weight (wt) and chest circumference (cc) were determined in ...

  17. Assessment of salivary flow rate: biologic variation and measure error.

    NARCIS (Netherlands)

    Jongerius, P.H.; Limbeek, J. van; Rotteveel, J.J.

    2004-01-01

    OBJECTIVE: To investigate the applicability of the swab method in the measurement of salivary flow rate in multiple-handicap drooling children. To quantify the measurement error of the procedure and the biologic variation in the population. STUDY DESIGN: Cohort study. METHODS: In a repeated

  18. Variability of flow rate when collecting stimulated human parotid saliva

    NARCIS (Netherlands)

    Burlage, FR; Pijpe, J; Coppes, RP; Hemels, MEW; Meertens, H; Canrinus, A; Vissink, A

    2005-01-01

    The aim of this study was to estimate the accuracy and reproducibility of citric-acid-stimulated parotid saliva sampling. In healthy volunteers a strong correlation (r(2) = 0.79) between flow rates from the left and right parotid gland was observed. In patients with Sjogren's syndrome this

  19. 3D modeling and characterization of a calorimetric flow rate sensor for sweat rate sensing applications

    Science.gov (United States)

    Iftekhar, Ahmed Tashfin; Ho, Jenny Che-Ting; Mellinger, Axel; Kaya, Tolga

    2017-03-01

    Sweat-based physiological monitoring has been intensively explored in the last decade with the hopes of developing real-time hydration monitoring devices. Although the content of sweat (electrolytes, lactate, urea, etc.) provides significant information about the physiology, it is also very important to know the rate of sweat at the time of sweat content measurements because the sweat rate is known to alter the concentrations of sweat compounds. We developed a calorimetric based flow rate sensor using PolydimethylSiloxane that is suitable for sweat rate applications. Our simple approach on using temperature-based flow rate detection can easily be adapted to multiple sweat collection and analysis devices. Moreover, we have developed a 3D finite element analysis model of the device using COMSOL Multiphysics™ and verified the flow rate measurements. The experiment investigated flow rate values from 0.3 μl/min up to 2.1 ml/min, which covers the human sweat rate range (0.5 μl/min-10 μl/min). The 3D model simulations and analytical model calculations covered an even wider range in order to understand the main physical mechanisms of the device. With a verified 3D model, different environmental heat conditions could be further studied to shed light on the physiology of the sweat rate.

  20. The Effect of Electric Current and Strain Rate on Serrated Flow of Sheet Aluminum Alloy 5754

    Science.gov (United States)

    Zhao, Kunmin; Fan, Rong; Wang, Limin

    2016-03-01

    Electrically assisted tensile tests are carried out on sheet aluminum alloy AA5754 at electric current densities ranging from 0 to 30.4 A/mm2 and strain rates ranging from 10-3 to 10-1 s-1. The strain rate sensitivity and the serrated flow behavior are investigated in accordance with dynamic strain aging mechanism. The strain rate sensitivity changes from negative to positive and keeps increasing with current density. The tendency toward serrated flow is characterized by the onset of Portevin-Le Chatelier (PLC) instabilities, which are influenced by strain rate, temperature, and electric current. The evolutions of three types of serrated flow are observed and analyzed with respect to strain rate and current density. The magnitude of serration varies with strain rate and current density. The serrated flow can be suppressed by a high strain rate, a high temperature, or a strong electric current. The threshold values of these parameters are determined and discussed. Conventional oven-heated tensile tests are conducted to distinguish the electroplasticity. The flow stress reduces more in electrically assisted tension compared to oven-heated tension at the same temperature level. The electric current helps suppress the serrated flow at the similar temperature level of oven-heating.

  1. Autism's 'Worryingly' High Suicide Rates Spur Conference

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_165946.html Autism's 'Worryingly' High Suicide Rates Spur Conference Signs of ... News) -- High rates of suicide among people with autism are drawing specialists to a conference this week ...

  2. Direct Assessment of Vorticity Alignment with Local and Nonlocal Strain Rates in Turbulent Flows

    OpenAIRE

    Hamlington, Peter E.; Schumacher, Jörg; Dahm, Werner J. A.

    2008-01-01

    A direct Biot-Savart integration is used to decompose the strain rate into its local and nonlocal constituents, allowing the vorticity alignment with the local and nonlocal strain rate eigenvectors to be investigated. These strain rate tensor constituents are evaluated in a turbulent flow using data from highly-resolved direct numerical simulations. While the vorticity aligns preferentially with the intermediate eigenvector of the \\textit{combined} strain rate, as has been observed previously...

  3. Effect of gas flow rate on titanium sponge reaction

    Science.gov (United States)

    Wang, Zhiliang; Feng, Gaoping; Wang, Mingdong; Hong, Yanji

    2017-08-01

    This paper expounds the important application of titanium sponge adsorption in inert gas purification, the reaction mechanism of titanium with nitrogen and oxygen was introduced. Explored the relationship between the absorption capacity of sponge titanium on the active gas in air samples and the gas flow rate. The model of sponge titanium for flowing air absorption was established by data analysis. The designed experiment verified the relationship between the titanium processing capacity and the gas collecting device. Finally, the influence of the mass of the sponge titanium on the degassing capacity was studied through experiments.

  4. Flow simulation and high performance computing

    Science.gov (United States)

    Tezduyar, T.; Aliabadi, S.; Behr, M.; Johnson, A.; Kalro, V.; Litke, M.

    1996-10-01

    Flow simulation is a computational tool for exploring science and technology involving flow applications. It can provide cost-effective alternatives or complements to laboratory experiments, field tests and prototyping. Flow simulation relies heavily on high performance computing (HPC). We view HPC as having two major components. One is advanced algorithms capable of accurately simulating complex, real-world problems. The other is advanced computer hardware and networking with sufficient power, memory and bandwidth to execute those simulations. While HPC enables flow simulation, flow simulation motivates development of novel HPC techniques. This paper focuses on demonstrating that flow simulation has come a long way and is being applied to many complex, real-world problems in different fields of engineering and applied sciences, particularly in aerospace engineering and applied fluid mechanics. Flow simulation has come a long way because HPC has come a long way. This paper also provides a brief review of some of the recently-developed HPC methods and tools that has played a major role in bringing flow simulation where it is today. A number of 3D flow simulations are presented in this paper as examples of the level of computational capability reached with recent HPC methods and hardware. These examples are, flow around a fighter aircraft, flow around two trains passing in a tunnel, large ram-air parachutes, flow over hydraulic structures, contaminant dispersion in a model subway station, airflow past an automobile, multiple spheres falling in a liquid-filled tube, and dynamics of a paratrooper jumping from a cargo aircraft.

  5. Regional variations in nocturnal fluctuations in subcutaneous blood flow rate in the lower leg of man

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Jørgensen, B

    1991-01-01

    hyperaemic response was demonstrated at both the medial and lateral aspect of the leg. As for the degree of hyperaemia and the absolute blood flow rates in the different phases, there were some deviations between the medial and the lateral locations. However, a highly significant positive correlation......The purpose of the study was to investigate possible regional variations in recently discovered nocturnal fluctuations in subcutaneous blood flow rates. Approximately 90 min after going to sleep, a 100% blood flow rate increment, lasting about 100 min, has been demonstrated in the distal and medial...... aspect of the right lower leg of normal human subjects. In the present study subcutaneous adipose tissue blood flow rates were measured simultaneously in the right and left lower legs of 16 normal human subjects over 12-20 h ambulatory conditions. The 133Xe wash-out technique, portable CdTe(Cl) detectors...

  6. Preparative isolation and purification of bergapten and imperatorin from the medicinal plant Cnidium monnieri using high-speed counter-current chromatography by stepwise increasing the flow-rate of the mobile phase.

    Science.gov (United States)

    Lia, Hua-Bin; Chen, Feng

    2004-12-17

    A high-speed counter-current chromatography (HSCCC) method was developed for the preparative separation and purification of bergapten and imperatorin from the Chinese medicinal plant Cnidium monnieri (L.) Cusson. The crude extract was obtained by extraction with ethanol from the dried fruits of Cnidium monnieri (L.) Cusson under sonication. Preparative HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (5:5:5:5, v/v/v/v) was successfully performed by increasing the flow-rate of the mobile phase stepwise from 1.0 to 2.0 ml min(-1) after 180 min. The components purified and collected were analyzed by high-performance liquid chromatography. The method yielded 45.8 mg of bergapten at 96.5% purity and 118.3 mg of imperatorin at 98.2% purity from 500 mg of the crude extract in a single run. The recoveries of bergapten and imperatorin were 92.1 and 93.7%, respectively.

  7. High bit rate BPSK receiver

    Science.gov (United States)

    Osorio-Marti, J. A.; Sieiro, J. J.; Lopez-Villegas, J. M.

    2005-06-01

    This work presents a simple differentially BPSK receiver front-end using a novel schema without the need of an explicit carrier recovery system. The main principle of operation is the conversion of the incoming BPSK signal into an ASK signal having the same modulation pattern. Two versions of the system have been designed. One is intended to work at the 433.92 MHz ISM band and the other at 2 GHz frequency band. Accordingly, two prototypes of the system core, the BPSK to ASK converter circuit, have been implemented and tested. First a hybrid version for the low frequency operation and, second a multi chip module (MCM) for the 2 GHz frequency band. The system performance has been evaluated using Agilent Technologies Advanced Design System (ADS) platform. The ability to jointly perform system, circuit and EM simulations and co-simulations is the main advantage of this design tool. Obtained results indicate that modulation rates up to 20 Mbits/s for the hybrid version and up to 80 Mbits/s for the MCM version can be reached.

  8. Good production rate forecast based on flow, reservoir analysis

    Energy Technology Data Exchange (ETDEWEB)

    El-Feky, S.A.

    1987-03-16

    Well bore flow efficiencies under expected modes of production operations, coupled with a detailed reservoir description, are necessary for an accurate evaluation of production rate forecast. A production rate forecast for an offshore water-drive oil reservoir in the Gulf of Suez has been prepared. The best overall completion that exhibits both the highest initial producing rates and the long term producing efficiencies was determined for different wells. Three different flow configurations were examined. The wells were classified according to their productivity indices into Group I, Group II, and Group III, having average productivity indices of 53, 18 and 6 b/d/psi, respectively. The study was based on the performance of the three well groups. The Orkiszewski correlation for vertical multiphase pressure gradient calculation program available from Garrett Computing Systems was used to calculate bottom hole flowing pressures at a wide range of oil and water production rates with and without gas lift. Analysis of the expected reservoir performance was essential in evaluating the production forecast. Based on the results of the evaluation, reservoir operations, including well completions, control of water production, and gas lift requirements, have been recommended.

  9. Exchange Rate Regime, Real Exchange Rate, Trade Flows and Foreign Direct Investments: The case of Morocco

    OpenAIRE

    Bouoiyour, Jamal; Rey, Serge

    2005-01-01

    We study the behavior of the Real Effective Exchange Rate (REER) of the dirham against the European currencies (Europe of the 15), over the period 1960-2000 (annual data). We measure the volatility using standard deviation, and the misalignments as the difference between the actual REER and the equilibrium REER (NATREX model). We show that a rise of the volatility of the dirham reduces the trade flows (exports and imports). The misalignments affect also the trade flows: an overvaluation leads...

  10. A flux monitoring method for easy and accurate flow rate measurement in pressure-driven flows.

    Science.gov (United States)

    Siria, Alessandro; Biance, Anne-Laure; Ybert, Christophe; Bocquet, Lydéric

    2012-03-07

    We propose a low-cost and versatile method to measure flow rate in microfluidic channels under pressure-driven flows, thereby providing a simple characterization of the hydrodynamic permeability of the system. The technique is inspired by the current monitoring method usually employed to characterize electro-osmotic flows, and makes use of the measurement of the time-dependent electric resistance inside the channel associated with a moving salt front. We have successfully tested the method in a micrometer-size channel, as well as in a complex microfluidic channel with a varying cross-section, demonstrating its ability in detecting internal shape variations.

  11. Innovative model-based flow rate optimization for vanadium redox flow batteries

    Science.gov (United States)

    König, S.; Suriyah, M. R.; Leibfried, T.

    2016-11-01

    In this paper, an innovative approach is presented to optimize the flow rate of a 6-kW vanadium redox flow battery with realistic stack dimensions. Efficiency is derived using a multi-physics battery model and a newly proposed instantaneous efficiency determination technique. An optimization algorithm is applied to identify optimal flow rates for operation points defined by state-of-charge (SoC) and current. The proposed method is evaluated against the conventional approach of applying Faraday's first law of electrolysis, scaled to the so-called flow factor. To make a fair comparison, the flow factor is also optimized by simulating cycles with different charging/discharging currents. It is shown through the obtained results that the efficiency is increased by up to 1.2% points; in addition, discharge capacity is also increased by up to 1.0 kWh or 5.4%. Detailed loss analysis is carried out for the cycles with maximum and minimum charging/discharging currents. It is shown that the proposed method minimizes the sum of losses caused by concentration over-potential, pumping and diffusion. Furthermore, for the deployed Nafion 115 membrane, it is observed that diffusion losses increase with stack SoC. Therefore, to decrease stack SoC and lower diffusion losses, a higher flow rate during charging than during discharging is reasonable.

  12. THE OPTIMIZATION OF FLOW RATES OF AN EXTRUDER

    Directory of Open Access Journals (Sweden)

    I.O. Popoola

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: The article addresses how the flow rates of an extruder can be optimized. It mentions the plastic recycling industry as an example, which is only one of many solid waste recycling industries. The literature on flow rates is reviewed to demonstrate a gap that the current study aims to fills, in the hope that it will stimulate further research in a fertile area.

    AFRIKAANSE OPSOMMING: Die artikel adresseer die vraagstuk van vloeitempo van ‘n ekstrusieproses. Dit handel met ‘n voorbeeld van ‘n plastiekherwinningsproses wat spruit uit soliede afvalverwerking. ‘n Literatuurstudie toon hoedat die navorsing verdere areas wat braak lê, aanspreek in die hoop dat verdere studie gestimuleer sal word.

  13. High energy density redox flow device

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Yet-Ming; Carter, Craig W.; Ho, Bryan Y.; Duduta, Mihai; Limthongkul, Pimpa

    2017-10-10

    Redox flow devices are described in which at least one of the positive electrode or negative electrode-active materials is a semi-solid or is a condensed ion-storing electroactive material, and in which at least one of the electrode-active materials is transported to and from an assembly at which the electrochemical reaction occurs, producing electrical energy. The electronic conductivity of the semi-solid is increased by the addition of conductive particles to suspensions and/or via the surface modification of the solid in semi-solids (e.g., by coating the solid with a more electron conductive coating material to increase the power of the device). High energy density and high power redox flow devices are disclosed. The redox flow devices described herein can also include one or more inventive design features. In addition, inventive chemistries for use in redox flow devices are also described.

  14. Experiments in a flighted conveyor comparing shear rates in compressed versus free surface flows

    Science.gov (United States)

    Pohlman, Nicholas; Higgins, Hannah; Krupiarz, Kamila; O'Connor, Ryan

    2017-11-01

    Uniformity of granular flow rate is critical in industry. Experiments in a flighted conveyor system aim to fill a gap in knowledge of achieving steady mass flow rate by correlating velocity profile data with mass flow rate measurements. High speed images were collected for uniformly-shaped particles in a bottom-driven flow conveyor belt system from which the velocity profiles can be generated. The correlation of mass flow rates from the velocity profiles to the time-dependent mass measurements will determine energy dissipation rates as a function of operating conditions. The velocity profiles as a function of the size of the particles, speed of the belt, and outlet size, will be compared to shear rate relationships found in past experiments that focused on gravity-driven systems. The dimension of the linear shear and type of decaying transition to the stationary bed may appear different due to the compression versus dilation space in open flows. The application of this research can serve to validate simulations in discrete element modeling and physically demonstrate a process that can be further developed and customized for industry applications, such as feeding a biomass conversion reactor. Sponsored by NIU's Office of Student Engagement and Experiential Learning.

  15. In vivo label-free measurement of lymph flow velocity and volumetric flow rates using Doppler optical coherence tomography.

    Science.gov (United States)

    Blatter, Cedric; Meijer, Eelco F J; Nam, Ahhyun S; Jones, Dennis; Bouma, Brett E; Padera, Timothy P; Vakoc, Benjamin J

    2016-07-05

    Direct in vivo imaging of lymph flow is key to understanding lymphatic system function in normal and disease states. Optical microscopy techniques provide the resolution required for these measurements, but existing optical techniques for measuring lymph flow require complex protocols and provide limited temporal resolution. Here, we describe a Doppler optical coherence tomography platform that allows direct, label-free quantification of lymph velocity and volumetric flow rates. We overcome the challenge of very low scattering by employing a Doppler algorithm that operates on low signal-to-noise measurements. We show that this technique can measure lymph velocity at sufficiently high temporal resolution to resolve the dynamic pulsatile flow in collecting lymphatic vessels.

  16. Numerical modelling of flow pattern for high swirling flows

    Science.gov (United States)

    Parra, Teresa; Perez, J. R.; Szasz, R.; Rodriguez, M. A.; Castro, F.

    2015-05-01

    This work focuses on the interaction of two coaxial swirling jets. High swirl burners are suitable for lean flames and produce low emissions. Computational Fluid Dynamics has been used to study the isothermal behaviour of two confined jets whose setup and operating conditions are those of the benchmark of Roback and Johnson. Numerical model is a Total Variation Diminishing and PISO is used to pressure velocity coupling. Transient analysis let identify the non-axisymmetric region of reverse flow. The center of instantaneous azimuthal velocities is not located in the axis of the chamber. The temporal sampling evidences this center spins around the axis of the device forming the precessing vortex core (PVC) whose Strouhal numbers are more than two for Swirl numbers of one. Influence of swirl number evidences strong swirl numbers are precursor of large vortex breakdown. Influence of conical diffusers evidence the reduction of secondary flows associated to boundary layer separation.

  17. Numerical modelling of flow pattern for high swirling flows

    Directory of Open Access Journals (Sweden)

    Parra Teresa

    2015-01-01

    Full Text Available This work focuses on the interaction of two coaxial swirling jets. High swirl burners are suitable for lean flames and produce low emissions. Computational Fluid Dynamics has been used to study the isothermal behaviour of two confined jets whose setup and operating conditions are those of the benchmark of Roback and Johnson. Numerical model is a Total Variation Diminishing and PISO is used to pressure velocity coupling. Transient analysis let identify the non-axisymmetric region of reverse flow. The center of instantaneous azimuthal velocities is not located in the axis of the chamber. The temporal sampling evidences this center spins around the axis of the device forming the precessing vortex core (PVC whose Strouhal numbers are more than two for Swirl numbers of one. Influence of swirl number evidences strong swirl numbers are precursor of large vortex breakdown. Influence of conical diffusers evidence the reduction of secondary flows associated to boundary layer separation.

  18. Digital image processing based mass flow rate measurement of gas/solid two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Song Ding; Peng Lihui; Lu Geng; Yang Shiyuan [Tsinghua National Laboratory for Information Science and Technology, Department of Automation, Tsinghua University, Beijing, 100084 (China); Yan Yong, E-mail: lihuipeng@tsinghua.edu.c [University of Kent, Canterbury, Kent CT2 7NT (United Kingdom)

    2009-02-01

    With the rapid growth of the process industry, pneumatic conveying as a tool for the transportation of a wide variety of pulverized and granular materials has become widespread. In order to improve plant control and operational efficiency, it is essential to know the parameters of the particle flow. This paper presents a digital imaging based method which is capable of measuring multiple flow parameters, including volumetric concentration, velocity and mass flow rate of particles in the gas/solid two phase flow. The measurement system consists of a solid state laser for illumination, a low-cost CCD camera for particle image acquisition and a microcomputer with bespoke software for particle image processing. The measurements of particle velocity and volumetric concentration share the same sensing hardware but use different exposure time and different image processing methods. By controlling the exposure time of the camera a clear image and a motion blurred image are obtained respectively. The clear image is thresholded by OTSU method to identify the particles from the dark background so that the volumetric concentration is determined by calculating the ratio between the particle area and the total area. Particle velocity is derived from the motion blur length, which is estimated from the motion blurred images by using the travelling wave equation method. The mass flow rate of particles is calculated by combining the particle velocity and volumetric concentration. Simulation and experiment results indicate that the proposed method is promising for the measurement of multiple parameters of gas/solid two-phase flow.

  19. Image Enhancement for High frame-rate Neutron Radiography

    OpenAIRE

    Saito, Y; Ito, D.

    2015-01-01

    High frame rate neutron radiography has been utilized to investigate two-phase flow in a metallic duct. However, images obtained by high frame-rate neutron radiography suffered from severe statistical noise due to its short exposure time. In this study, a spatio-temporal filter was applied to reduce the noise in the sequence images obtained by high frame-rate neutron radiography. Experiments were performed at the B4-port of the Research Reactor Institute, Kyoto University, which has a thermal...

  20. High frequency image-based flow detection

    Energy Technology Data Exchange (ETDEWEB)

    Chung, R [National Heart and Lung Institute, Royal Brompton Hospital, London SW3 6NP (United Kingdom); Prager, R W [Dept. of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Gee, A H [Dept. of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Treece, G M [Dept. of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

    2004-01-01

    Tumour angiogenesis refers to neovascular development on a microvascular scale and is an early indicator of cancer. Prototype high frequency pulsed Doppler systems using 50 MHz transducers have been reported to detect microvascular flow in vessels 0.02 mm to 0.5 mm in diameter at superficial depths of 0.5 mm. Detecting flow in microvasculature at deeper depths requires lower frequency transducers with a resulting tradeoff in spatial resolution. Using a 22 MHz transducer, we demonstrate a speckle decorrelation technique to detect in vitro flow in soft tubing of 0.5 mm diameter at a depth of 2 cm. This image-based decorrelation technique is capable of detecting flow in significantly narrower diameters down to 0.125 mm by decreasing the region of interest.

  1. Heterogeneous flow during high-pressure torsion

    Directory of Open Access Journals (Sweden)

    Roberto B. Figueiredo

    2013-06-01

    Full Text Available High-Pressure Torsion (HPT has attracted significant attention in recent years as an effective technique to process ultrafine and nanostructured materials. The hydrostatic pressure developed during processing prevents the occurrence of cracks and the low thickness to diameter ratio provides the opportunity for developing high strains at low numbers of rotations. The present work analyses the plastic flow during HPT. Experimental results and computer modeling are used to describe heterogeneous plastic flow. It is shown that variations in structure, hardness and in the distribution of strain are observed along the disc thickness. The sources of these heterogeneities are discussed.

  2. Flow rate calibration to determine cell-derived microparticles and homogeneity of blood components.

    Science.gov (United States)

    Noulsri, Egarit; Lerdwana, Surada; Kittisares, Kulvara; Palasuwan, Attakorn; Palasuwan, Duangdao

    2017-08-01

    Cell-derived microparticles (MPs) are currently of great interest to screening transfusion donors and blood components. However, the current approach to counting MPs is not affordable for routine laboratory use due to its high cost. The current study aimed to investigate the potential use of flow-rate calibration for counting MPs in whole blood, packed red blood cells (PRBCs), and platelet concentrates (PCs). The accuracy of flow-rate calibration was investigated by comparing the platelet counts of an automated counter and a flow-rate calibrator. The concentration of MPs and their origins in whole blood (n=100), PRBCs (n=100), and PCs (n=92) were determined using a FACSCalibur. The MPs' fold-changes were calculated to assess the homogeneity of the blood components. Comparing the platelet counts conducted by automated counting and flow-rate calibration showed an r2 of 0.6 (y=0.69x+97,620). The CVs of the within-run and between-run variations of flow-rate calibration were 8.2% and 12.1%, respectively. The Bland-Altman plot showed a mean bias of -31,142platelets/μl. MP enumeration revealed both the difference in MP levels and their origins in whole blood, PRBCs, and PCs. Screening the blood components demonstrated high heterogeneity of the MP levels in PCs when compared to whole blood and PRBCs. The results of the present study suggest the accuracy and precision of flow-rate calibration for enumerating MPs. This flow-rate approach is affordable for assessing the homogeneity of MPs in blood components in routine laboratory practice. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Behaviour of uranium alloys at high loading rates

    Energy Technology Data Exchange (ETDEWEB)

    Rolc, S.; Pechacek, J.; Krejci, J. (Ceskoslovenska Akademie Ved, Brno (CS). Ustav Fyzikalni Metalurgie); Buchar, J.

    1991-10-01

    The mechanical behaviour of depleted uranium, uranium with molybdenum, niobium, titanium and rhenium was investigated under high strain rates. The Hopkinson split pressure bar was used. The spallation of these materials was also studied. The correlation of the spall strength, {sigma}{sub c}, with flow properties was found. 11 refs., 4 figs., 1 tab..

  4. Carbon film deposition from high velocity rarefied flow

    Energy Technology Data Exchange (ETDEWEB)

    Rebrov, A.K., E-mail: rebrov@itp.nsc.ru; Emelyanov, A.A.; Yudin, I.B.

    2015-01-30

    The presented study is based on the idea of the activation of a gas-precursor high velocity flow by hot wire. The wire forms the channel for flow before expansion to substrate. The construction allows change of the specific flow rate, velocity, composition and temperature of a gas mixture by studying the film synthesis in conditions from free molecular to continuum flow at velocities from hundreds to thousands of m/s. At a high pressure, the film has typical and unusual hexagonal incorporations for diamond tetragonal particles. Raman spectrum with the pronounced diamond peak is typical for diamond-like film. X-ray diffraction points in the presence of lonsdaleite. Conditions of deposition were simulated by Monte Carlo method. Collisions with hot surfaces and chemical transformations were taken into consideration as well.

  5. Mercury flow experiments. 4th report Measurements of erosion rate caused by mercury flow

    CERN Document Server

    Kinoshita, H; Hino, R; Kaminaga, M

    2002-01-01

    The Japan Atomic Energy Research Institute (JAERI) and the High Energy Accelerator Research Organization (KEK) are promoting a construction plan of the Material-Life Science Facility, which is consisted of a Muon Science Facility and a Neutron Scattering Facility, in order to open up the new science fields. The Neutron Scattering Facility will be utilized for advanced fields of Material and Life science using high intensity neutron generated by the spallation reaction of a 1 MW pulsed proton beam and mercury target. Design of the spallation mercury target system aims to obtain high neutron performance with high reliability and safety. Since the target system is using mercury as the target material and contains large amount of radioactive spallation products, it is necessary to estimate reliability for strength of instruments in a mercury flow system during lifetime of the facility. Piping and components in the mercury flow system would be damaged by erosion with mercury flow, since these components will be we...

  6. High Data Rate Architecture (HiDRA)

    Science.gov (United States)

    Hylton, Alan; Raible, Daniel

    2016-01-01

    high-rate laser terminals. These must interface with the existing, aging data infrastructure. The High Data Rate Architecture (HiDRA) project is designed to provide networked store, carry, and forward capability to optimize data flow through both the existing radio frequency (RF) and new laser communications terminal. The networking capability is realized through the Delay Tolerant Networking (DTN) protocol, and is used for scheduling data movement as well as optimizing the performance of existing RF channels. HiDRA is realized as a distributed FPGA memory and interface controller that is itself controlled by a local computer running DTN software. Thus HiDRA is applicable to other arenas seeking to employ next-generation communications technologies, e.g. deep space. In this paper, we describe HiDRA and its far-reaching research implications.

  7. Design and optimization of a large flow rate booster pump in SWRO energy recovery system

    Science.gov (United States)

    Lai, Z. N.; Wu, P.; Wu, D. Z.; Wang, L. Q.

    2013-12-01

    Seawater reverse osmosis (SWRO) is a high energy-consumption industry, so energy efficiency is an important issue. Energy recovery systems, which contain a pressure exchanger and a booster pump, are widely used in SWRO plants. As a key part of energy recovery system, the difficulty of designing booster pumps lies in high inlet pressure, high medium causticity and large flow rate. High inlet pressure adds difficulties to seal design, and large flow rate and high efficiency requirement bring high demand for hydraulic design. In this paper, a 625 m3/h booster pump is designed and optimized according to the CFD (Computational Fluid Dynamics) simulation results. The impeller and volute is well designed, a new type of high pressure mechanical seal is applied and axial force is well balanced. After optimization based on blade redesign, the efficiency of the pump was improved. The best efficiency reaches more than 85% at design point according to the CFD simulation result.

  8. Highly Turbulent Taylor-Couette Flow

    NARCIS (Netherlands)

    van Gils, Dennis Paulus Maria

    2011-01-01

    The research issues addressed in this mostly experimental thesis concern highly turbulent Taylor-Couette (TC) flow (Re>105, implying Ta>1011). We study it on a fundamental level to aid our understanding of (TC) turbulence and to make predictions towards astrophysical disks, and at a practical level

  9. Low-Flow-Rate Dry-Powder Feeder

    Science.gov (United States)

    Ramsey, Keith E.

    1994-01-01

    Apparatus feeds small, precise flow of dry powder through laser beam of optical analyzer, measuring patterns of light created by forward scattering (Fraunhofer diffraction) of laser beam from powder particles. From measurement, statistical distribution of sizes of powder particles computed. Developed for analyzing particle-size distributions of solid-propellant powders. Also adapted to use in pharmaceutical industry, in manufacture of metal powder, and in other applications in which particle-size distributions of materials used to control rates of chemical reactions and/or physical characteristics of processes.

  10. Flow Interaction With Highly Flexible Structures

    Science.gov (United States)

    Shoele, Kourosh

    Studying the interaction between fluid and structure is an essential step towards the understanding of many engineering and physical problems, from the flow instability of structures to the biolocomotion of insects, birds and fishes. The simulation of such problems is computationally challenging. This justifies the attempts to develop more sophisticated and more efficient numerical models of fluid-solid interactions. In this dissertation, we proposed numerical models both in potential flow and fully viscous flow for the interaction of immersed structure with a strongly unsteady flow. In particular we have developed efficient approaches to study two groups of problems, the flow interaction with skeleton-reinforced fish fins and flow interaction with highly flexible bluff bodies. Fins of bony fishes are characterized by a skeleton-reinforced membrane structure consisting of a soft collagen membrane strengthened by embedded flexible rays. Morphologically, each ray is connected to a group of muscles so that the fish can control the rotational motion of each ray individually, enabling multi-degree of freedom control over the fin motion and deformation. We have developed fluid-structure interaction models to simulate the kinematics and dynamic performance of a structurally idealized fin. The first method includes a boundary-element model of the fluid motion and a fully-nonlinear Euler-Bernoulli beam model of the embedded rays. In the second method, we use an improved immersed boundary approach. Using these models, we study thrust generation and propulsion efficiency of the fin at different combinations of parameters at both high-Re and intermediate-Re flow. Effects of kinematic as well as structural properties are examined. It has been illustrated that the fish's capacity to control the motion of each individual ray, as well as the anisotropic deformability of the fin determined by distribution of the rays (especially the detailed distribution of ray stiffness), is

  11. Remote Quantification of Smokestack Total Effluent Mass Flow Rates Using Imaging Fourier-Transform Spectroscopy

    Science.gov (United States)

    2011-03-01

    total effluent mass flow rates by combining spectrally-determined species concentrations with flow rates estimated via analysis of sequential images...of the flow velocity. Final effluent mass flow rates for CO2 and SO2 of 13.5 +- 3.78 kg/s and 71.3 +- 19.3 g/s were in good agreement with in situ

  12. Molecule-based approach for computing chemical-reaction rates in upper atmosphere hypersonic flows.

    Energy Technology Data Exchange (ETDEWEB)

    Gallis, Michail A.; Bond, Ryan Bomar; Torczynski, John Robert

    2009-08-01

    This report summarizes the work completed during FY2009 for the LDRD project 09-1332 'Molecule-Based Approach for Computing Chemical-Reaction Rates in Upper-Atmosphere Hypersonic Flows'. The goal of this project was to apply a recently proposed approach for the Direct Simulation Monte Carlo (DSMC) method to calculate chemical-reaction rates for high-temperature atmospheric species. The new DSMC model reproduces measured equilibrium reaction rates without using any macroscopic reaction-rate information. Since it uses only molecular properties, the new model is inherently able to predict reaction rates for arbitrary nonequilibrium conditions. DSMC non-equilibrium reaction rates are compared to Park's phenomenological non-equilibrium reaction-rate model, the predominant model for hypersonic-flow-field calculations. For near-equilibrium conditions, Park's model is in good agreement with the DSMC-calculated reaction rates. For far-from-equilibrium conditions, corresponding to a typical shock layer, the difference between the two models can exceed 10 orders of magnitude. The DSMC predictions are also found to be in very good agreement with measured and calculated non-equilibrium reaction rates. Extensions of the model to reactions typically found in combustion flows and ionizing reactions are also found to be in very good agreement with available measurements, offering strong evidence that this is a viable and reliable technique to predict chemical reaction rates.

  13. Measuring device for purging water flow rate in control rod drive

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Hiroshi.

    1993-11-12

    The device of the present invention enables highly accurate measurement for an amount of purging water supplied to control rod drives of a BWR type reactor. That is, purging water is supplied from an inlet of a scram line of the control rod drives. A temperature measuring portion is disposed, for measuring temperature fluctuation of purging water, to a hydropressure control unit for providing pressure and flow rate of water required for supplying the purging water and scram operation. An instrumentation section is disposed for calculating the flow rate of purging water based on the measured data obtained in the section. An output device is disposed for outputting a flow rate value of the purging water based on the result of the calculation obtained therein. With such a constitution, flow rate of the purging water can be measured quantitatively at the hydropressure control unit. Accordingly, influences, such as fluctuation of reactor core temperature are reduced, and accuracy for the measurement of the purging water flow rate is improved. As a result, reactor safety and maintainability can be improved. (I.S.).

  14. Physiologic effects of nasopharyngeal administration of supplemental oxygen at various flow rates in healthy neonatal foals.

    Science.gov (United States)

    Wong, David M; Alcott, Cody J; Wang, Chong; Hay-Kraus, Bonnie L; Buchanan, Benjamin R; Brockus, Charles W

    2010-09-01

    To evaluate the effects of various flow rates of oxygen administered via 1 or 2 nasal cannulae on the fraction of inspired oxygen concentration (FIO2) and other arterial blood gas variables in healthy neonatal foals. 9 healthy neonatal (3- to 4-day-old) foals. In each foal, a nasal cannula was introduced into each naris and passed into the nasopharynx to the level of the medial canthus of each eye; oxygen was administered at 4 flow rates through either 1 or both cannulae (8 treatments/foal). Intratracheal FIO2, intratracheal end-tidal partial pressure of carbon dioxide, and arterial blood gas variables were measured before (baseline) and during unilateral and bilateral nasopharyngeal delivery of 50, 100, 150, and 200 mL of oxygen/kg/min. No adverse reactions were associated with administration of supplemental oxygen except at the highest flow rate, at which the foals became agitated. At individual flow rates, significant and dose-dependent increases in FIO2, PaO2, and oxygen saturation of hemoglobin (SaO2) were detected, compared with baseline values. Comparison of unilateral and bilateral delivery of oxygen at similar cumulative flow rates revealed no differences in evaluated variables. Results indicated that administration of supplemental oxygen via nasal cannulae appeared to be a highly effective means of increasing FIO2, PaO2, and SaO2 in neonatal foals. These findings may provide guidance for implementation of oxygen treatment in hypoxemic neonatal foals.

  15. Miniaturized microDMFC using silicon microsystems techniques: performances at low fuel flow rates

    Science.gov (United States)

    Kamitani, Ai; Morishita, Satoshi; Kotaki, Hiroshi; Arscott, Steve

    2008-12-01

    This paper reports the design, fabrication and characterization of high performance miniaturized micro direct methanol fuel cells (microDMFC) functioning at room temperature under a forced low input fuel flow rate (fuel flow rate of 5.52 µL min-1 for a fuel cell surface area as small as 0.3 cm2 (corresponding to a fuel use efficiency of 14.1% at 300 K). At a lower flow rate of 1.38 µL min-1, the fuel use efficiency rises to 20.1% although the power density falls to 4.3 mW cm-2. The study revealed that improved room temperature cell performances in terms of power density can be achieved at low flow rates (fuel cell area and (ii) reducing the microchannel cross-section. The study also revealed that higher fuel use efficiencies are obtained at lower fuel flow rates. Fuel (methanol) for the anode and an oxidant (air) for the cathode are supplied via a compact serpentine network of micron-size microfluidic and gas microchannels; by using silicon microsystems techniques we also render the fuel cell compatible with other silicon technologies such as microelectronics and micro- and nanoelectromechanical systems (MEMS/NEMS).

  16. Experimental Studies for Determining Gas Flow Rate Accidental Release on Linear Part of Pipeline

    Science.gov (United States)

    Fetisov, V. G.; Nikolaev, A. K.; Lykov, Y. V.

    2017-10-01

    The method of determining the flow rate of gas in the gas-dynamic resistance of a medium gas stream with high linear speed was studied. The reduction of the density of the gas is a result of its expansion. Multiple calculations of gas losses were evaluated. Calculation is set by loss of gas depending on the area of the pipeline damage. A comparative analysis was done. In order to establish a functional empirical dependence of the flow rate on the whole on the parameters of the leakage process, a series of experiments was conducted on a test bench and their processing was carried out. In experiments conducted, the effect of pressure and temperature in the receiver was evaluated, the physical properties of the gas and the diameter of the hole were predetermined by the limits of the amount of the whole flow rate in critical conditions, as well as the critical regime of gas leakage.

  17. High-Rate Receiver Design Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an initial architectural and preliminary hardware design study for a high-rate receiver capable of decoding modulation suites specified by CCSDS 413.0-G-1...

  18. Miniature, high efficiency transducers for use in ultrasonic flow meters

    Science.gov (United States)

    Saikia, Meghna

    This thesis is concerned with the development of a new type of miniature, high efficiency transducer for use in ultrasonic flow meters. The proposed transducer consists of a thin plate of a suitable piezoelectric material on which an inter-digital transducer is fabricated for the generation and detection of plate acoustic waves. When immersed in a fluid medium, this device can convert energy from plate acoustic waves (PAWs) into bulk acoustic waves (BAWs) and vice versa. It is shown that this mode coupling principle can be used to realize efficient transducers for use in ultrasonic flow meters. This transducer can be mounted flush with the walls of the pipe through which fluid is flowing, resulting in minimal disturbance of fluid flow. A prototype flow cell using these transducers has been designed and fabricated. The characteristics of this device have been measured over water flow rates varying from 0 to 7.5 liters per minute and found to be in good agreement with theory. Another attractive property of the new transducers is that they can be used to realize remotely read, passive, wireless flow meters. Details of methods that can be used to develop this wireless capability are described. The research carried out in this thesis has applications in several other areas such as ultrasonic nondestructive evaluation (NDE), noncontact or air coupled ultrasonics, and for developing wireless capability in a variety of other acoustic wave sensors.

  19. The Piece Wise Linear Reactive Flow Rate Model

    Science.gov (United States)

    Vitello, Peter; Souers, P. Clark

    2006-07-01

    For non-ideal explosives a wide range of behavior is observed in experiments dealing with differing sizes and geometries. A predictive detonation model must be able to reproduce many phenomena including such effects as: variations in the detonation velocity with the radial diameter of rate sticks; slowing of the detonation velocity around gentle corners; production of dead zones for abrupt corner turning; failure of small diameter rate sticks; and failure for rate sticks with sufficiently wide cracks. Most models have been developed to explain one effect at a time. Often, changes are made in the input parameters used to fit each succeeding case with the implication that this is sufficient for the model to be valid over differing regimes. We feel that it is important to develop a model that is able to fit experiments with one set of parameters. To address this we are creating a new generation of models that are able to produce better fitting to individual data sets than prior models and to simultaneous fit distinctly different regimes of experiments. Presented here are details of our new Piece Wise Linear reactive flow model applied to LX-17.

  20. A review of reaction rates in high temperature air

    Science.gov (United States)

    Park, Chul

    1989-01-01

    The existing experimental data on the rate coefficients for the chemical reactions in nonequilibrium high temperature air are reviewed and collated, and a selected set of such values is recommended for use in hypersonic flow calculations. For the reactions of neutral species, the recommended values are chosen from the experimental data that existed mostly prior to 1970, and are slightly different from those used previously. For the reactions involving ions, the recommended rate coefficients are newly chosen from the experimental data obtained more recently. The reacting environment is assumed to lack thermal equilibrium, and the rate coefficients are expressed as a function of the controlling temperature, incorporating the recent multitemperature reaction concept.

  1. The main natural lows of high-rate coal pyrolysis

    Directory of Open Access Journals (Sweden)

    Chemyavsky Nikola V.

    2003-01-01

    Full Text Available The importance of coal pyrolysis studies for the development of energy technologies is evident, since pvrolysis is the first stage of any process of coal thermal conversion. In combustion, pyrolysis determines conditions of coal ignition and the rate of char after-burning, in gasification, pyrolysis determines total yield of gasification products. It must be noted that in modern energy technologies pyrolysis occurs at high late of coal particle heating (=10 K/s for different fluidized bed, or FB-technologies or super-high-rate (>10**5 K/s for entrained-flow gasification, and in some of them at high pressure. In CETI during last 12 years the detailed study of pyrolysis in FB laboratory-scale PYROLYSIS-D plant and entramed-flow pilot-scale GSP-01 plant, was carried out. In this paper main results of mentioned investigations are given. Kinetic constants for bituminous coals and anthracite high heating rates in entrained flow for high temperatures (>1500 °C and >1900 °C, and in fluidized bed conditions in temperature range 972-1273 K. In order to describe data obtained in fluidized bed conditions, G--model based method of calculation of devolatization dynamics was suited to FB heating conditions. Calculated and experimental kinetic data are in good agreement. The result proves that at FB-pvrolysis conditions intrinsic mass-transfer limitations are negligible and devolatilization is really kinetic-controlled.

  2. Copepod feeding currents : flow patterns, filtration rates and energetics

    NARCIS (Netherlands)

    van Duren, L.A; Stamhuis, E.J; Videler, J.J

    Particle image velocimetry was used to construct a quasi 3-dimensional image of the flow generated by the feeding appendages of the calanoid copepod Temora longicornis. By scanning layers of flow, detailed information was obtained on flow velocity and velocity gradients. The flow around feeding T.

  3. Design and construction of a novel Coriolis mass flow rate meter

    NARCIS (Netherlands)

    Mehendale, A.; Zwikker, Rini; Jouwsma, Wybren

    2009-01-01

    The Coriolis principle for measuring flow rates has great advantages compared to other flow measurement principles, the most important being that mass flow is measured directly. Up to now the measurement of low flow rates posed a great challenge. In a joint research project, the University of Twente

  4. Solid Hydrogen Particles and Flow Rates Analyzed for Atomic Fuels

    Science.gov (United States)

    Palaszewski, Bryan A.

    2003-01-01

    The experiments were conducted at Glenn's Small Multipurpose Research Facility (SMIRF, ref. 5). The experimental setup was placed in the facility's vacuum tank to prevent heat leaks and subsequent boiloff of the liquid helium. Supporting systems maintained the temperature and pressure of the liquid helium bath where the solid particles were created. Solid hydrogen particle formation was tested from February 23 to April 2, 2001. Millimeter-sized solid-hydrogen particles were formed in a Dewar of liquid helium as a prelude to creating atomic fuels and propellants for aerospace vehicles. Atomic fuels or propellants are created when atomic boron, carbon, or hydrogen is stored in solid hydrogen particles. The current testing characterized the solid hydrogen particles without the atomic species, as a first step to creating a feed system for the atomic fuels and propellants. This testing did not create atomic species, but only sought to understand the solid hydrogen particle formation and behavior in the liquid helium. In these tests, video images of the solid particle formation were recorded, and the total mass flow rate of the hydrogen was measured. The mass of hydrogen that went into the gaseous phase was also recorded using a commercially available residual gas analyzer. The temperatures, pressures, and flow rates of the liquids and gases in the test apparatus were recorded as well. Testing conducted in 1999 recorded particles as small as 2 to 5 mm in diameter. The current testing extended the testing conditions to a very cold Dewar ullage gas of about 20 to 90 K above the 4 K liquid helium. With the very cold Dewar gas, the hydrogen freezing process took on new dimensions, in some cases creating particles so small that they seemed to be microscopic, appearing as infinitesimally small scintillations on the videotaped images.

  5. Aminophylline Improves Urine Flow Rates but Not Survival in ...

    African Journals Online (AJOL)

    Introduction: Acute kidney injury (AKI) morbidity and mortality rates remain high. Variable AKI outcomes have been reported in association with aminophylline treatment. This study evaluated AKI outcome in a group of Nigerian children treated with aminophylline. Methods: This is a retrospective study of AKI in children ...

  6. The influence of urinary flow rate on mercury excretion in children.

    Science.gov (United States)

    Trachtenberg, Felicia; Barregård, Lars; McKinlay, Sonja

    2010-01-01

    There is limited literature concerning the effect of urinary flow rate on mercury excretion at low-level exposure. The aim of the present study is to examine the influence of urinary flow rate on mercury excretion in children. Also of interest is the influence of flow rate on creatinine excretion and creatinine-corrected mercury, which arisearises with spot urine samples. A substudy of the New England Children's Amalgam Trial collected pairs of urine samples from children aged 10-16 years: a timed overnight collection and a spot daytime sample collected the following day. These samples were analyzed for mercury and creatinine concentration. Regression analysis was used to model the effect of urinary flow rate in the timed overnight samples. A paired t-test compared concentrations and creatinine-corrected mercury between overnight and daytime samples. Creatinine excretion rate (mg/h) increased significantly with urinary flow rate (mL/h), whereas creatinine concentration (g/L) decreased with flow rate. We found a non-significant increase in mercury excretion rate (ng/h) with flow rate, and mercury concentration decreased with flow rate. Mercury and creatinine concentrations were significantly higher in the overnight compared to daytime samples. For creatinine-corrected mercury, no significant impact of urinary flow rate was found. Although the creatinine excretion rate, and probably the mercury excretion rate, increased with urinary flow rate, the mercury/creatinine ratio seemed relatively unaffected by urinary flow rate. Copyright 2009 Elsevier GmbH. All rights reserved.

  7. Analysis of flow decay potential on Galileo. [oxidizer flow rate reduction by iron nitrate precipitates

    Science.gov (United States)

    Cole, T. W.; Frisbee, R. H.; Yavrouian, A. H.

    1987-01-01

    The risks posed to the NASA's Galileo spacecraft by the oxidizer flow decay during its extended mission to Jupiter is discussed. The Galileo spacecraft will use nitrogen tetroxide (NTO)/monomethyl hydrazine bipropellant system with one large engine thrust-rated at a nominal 400 N, and 12 smaller engines each thrust-rated at a nominal 10 N. These smaller thrusters, because of their small valve inlet filters and small injector ports, are especially vulnerable to clogging by iron nitrate precipitates formed by NTO-wetted stainless steel components. To quantify the corrosion rates and solubility levels which will be seen during the Galileo mission, corrosion and solubility testing experiments were performed with simulated Galileo materials, propellants, and environments. The results show the potential benefits of propellant sieving in terms of iron and water impurity reduction.

  8. Numerical Analysis of Inlet Gas-Mixture Flow Rate Effects on Carbon Nanotube Growth Rate

    Directory of Open Access Journals (Sweden)

    B. Zahed

    2013-01-01

    Full Text Available The growth rate and uniformity of Carbon Nano Tubes (CNTs based on Chemical Vapor Deposition (CVD technique is investigated by using a numerical model. In this reactor, inlet gas mixture, including xylene as carbon source and mixture of argon and hydrogen as  carrier gas enters into a horizontal CVD reactor at atmospheric pressure. Based on the gas phase and surface reactions, released carbon atoms are grown as CNTs on the iron catalysts at the reactor hot walls. The effect of inlet gas-mixture flow rate, on CNTs growth rate and its uniformity is discussed. In addition the velocity and temperature profile and also species concentrations throughout the reactor are presented.

  9. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    Energy Technology Data Exchange (ETDEWEB)

    Prasetyaningrum, A., E-mail: ajiprasetyaningrum@gmail.com; Ratnawati,; Jos, B. [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University Jl. Prof. H. Soedarto Tembalang, Semarang, Central Java, Indonesia, 50276 (Indonesia)

    2015-12-29

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O{sub 3}) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

  10. GROWTH RATE DISPERSION (GRD OF THE (010 FACE OF BORAX CRYSTALS IN FLOWING SOLUTION

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available The growth rates of borax crystals from aqueous solutions in the (010 direction at various flow rates were measured. The observed variations of the growth rate can be represented by a normal distribution.  It was found that there is no correlation between growth rate distribution and solution flow under these experimental conditions.   Keywords: Growth rate dispersion (GRD, borax, flow rate

  11. Dependence of Selected Water Quality Parameters on Flow Rates in River Profiles in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Eduard Hanslík

    2016-06-01

    The results show that in the monitored profiles, there is a direct relationship with flow rate in case of N-NO3-, suspended solids and O2. Temperature shows an inverse relationship with the flow rate. Other parameters show different relationship with the flow rate in individual monitored profiles or do not show statistically significant relation.

  12. Determination of flow rates of oil, water and gas in pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Roach, G.J.; Watt, J.S.; Zastawny, H.W. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lucas Heights, NSW (Australia). Div. of Mineral Physics

    1993-12-31

    This paper describes a multiphase flow meter developed by CSIRO for determining of the flow rates of oil, water and gas in high pressure pipelines, and the results of a trial of this flow meter on an offshore oil platform. Two gamma-ray transmission gauges are mounted about a pipeline carrying the full flow of oil, water and gas. The flow rates are determined by combining single energy gamma-ray transmission measurements which determine the mass per unit area of fluids in the gamma-ray beam as a function of time, dual energy gamma-ray transmission (DUET) which determine the approximate mass fraction of oil in the liquids, cross-correlation of gamma-ray transmission measurements, with one gauge upstream of the other, which determines flow velocity, pressure and temperature measurements, and knowledge of the specific gravities of oil and (salt) water, and solubility of the gas in the liquids, all as a function of pressure and temperature. 3 figs.

  13. Impact of extracorporeal blood flow rate on blood pressure, pulse rate and cardiac output during haemodialysis

    DEFF Research Database (Denmark)

    Schytz, Philip Andreas; Mace, Maria Lerche; Soja, Anne Merete Boas

    2015-01-01

    BACKGROUND: If blood pressure (BP) falls during haemodialysis (HD) [intradialytic hypotension (IDH)] a common clinical practice is to reduce the extracorporeal blood flow rate (EBFR). Consequently the efficacy of the HD (Kt/V) is reduced. However, only very limited knowledge on the effect......L/min diastolic BP, mean arterial pressure, PR and CO remained unchanged. CONCLUSION: Our study does not show any consistent trend in BP changes by a reduction in EBFR. Reduction in EBFR if BP falls during IDH is thus not supported. However, none of the patients experienced IDH. Further studies are required...... to evaluate the impact of changes in EBFR on BP during IDH....

  14. [High flow vascular malformations in children].

    Science.gov (United States)

    López Gutiérrez, J C; Ros, Z; Martínez, L; Díaz, M; Leal, N; Rivas, S; Hernández, F

    2002-10-01

    Unlike hemangiomas and low-flow vascular malformations which are very common in children, arterial anomalies have small incidence. Differential diagnosis is difficult, and needs a physician familiarized with vascular anomalies. Appropriate treatment must be planned by multidisciplinary team considering the patient's age, and anatomical location. Twenty-eight children with high flow vascular malformations have been treated since 1990 at La Paz Children's Hospital Vascular Anomalies Program. We excluded of the study group patients with central nervous system lesions. 85% of the patients had malformation in stage I or II (according the ISSVA accepted Schöbinger stating) and most of them were erroneously diagnosed as hemangioms with a variety of inappropriate treatments previously performed. Doppler Ultrasound and Magnetic Resonance confirmed malformation flow and extension. Angiography and selective embolization was only considered as therapeutic approach in candidates to surgical resection. 16 patients underwent complete resection of the malformation including one foot and two fingers amputation and five more incomplete resection of the ulcerate area. In conclusion, we did not find age at onset, sex and symptoms relationship. Laser, radiotherapy, surgical ligation or partial resection must be considered inappropriate therapies which may stimulate AVM exacerbation. Only radical surgical procedure after selective endovascular embolization will be successful but then reconstructive surgery should be performed to achieve good aesthetic and functional results.

  15. Intrapericardial denervation - Radial artery blood flow and heart rate responses to LBNP

    Science.gov (United States)

    Mckeever, Kenneth H.; Skidmore, Michael G.; Keil, Lanny C.; Sandler, Harold

    1990-01-01

    The effects of intrapericardial denervation on the radial artery blood flow velocity (RABFV) and heart rate (HR) responses to LBNP in rhesus monkeys were investigated by measuring the RABFV transcutaneously by a continuous-wave Doppler ultrasonic flowmeter in order to derive an index of forearm blood flow response to low (0 to -20 mm Hg) and high (0 to -60 mm Hg) ramp exposures during supine LBNP. Four of the eight subjects were subjected to efferent and afferent cardiac denervation. It was found that, during low levels of LBNP, monkeys with cardiac denervation exhibited no cardiopulmonary baroreceptor-mediated change in the RABFV or HR, unlike the intact animals, which showed steady decreases in RABFV during both high- and low-pressure protocols. It is suggested that forearm blood flow and HR responses to low-level LBNP, along with pharmacological challenge, are viable physiological tests for verifying the completeness of atrial and cardiopulmonary baroreceptor denervation.

  16. Non-contact flow gauging for the extension and development of rating curves

    Science.gov (United States)

    Perks, Matthew; Large, Andy; Russell, Andy

    2015-04-01

    Accurate measurement of river discharge is fundamental to understanding hydrological processes, associated hazards and ecological responses within fluvial systems. Established protocols for determining river discharge are partial, predominantly invasive and logistically difficult during high flows. There is demand for new methods for accurate quantification of flow velocity under high-flow/flood conditions to in turn enable better post-event reconstruction of peak discharge. As a consequence considerable effort has been devoted to the development of innovative technologies for the representation of flow in open channels. Remotely operated fixed and mobile systems capable of providing quantitative estimates of instantaneous and time-averaged flow characteristics using non-contact methods has been a major development. Amongst the new approaches for stand-alone continuous monitoring of surface flows is Large Scale Particle Image Velocimetry (LSPIV). Here we adapt the LSPIV concept, to provide continuous discharge measurements in non-uniform channels with complex flow conditions. High Definition videos (1080p; 30fps) of the water surface are acquired at 5 minute intervals. The image is rectified to correct for perspective distortion using a new, open source tool which minimises errors resulting from oblique image capture. Naturally occurring artefacts on the water surface (e.g. bubbles, debris, etc.) are tracked with the Kanade-Lucas-Tomasi (KLT) algorithm. The data generated is in the form of a complex surface water velocity field which can be interrogated to extract a range of hydrological information such as the streamwise velocity at a cross-section of interest, or even allow the interrogation of hydrodynamic flow structures. Here we demonstrate that this approach is capable of generating river discharge data comparable to concurrent measurements made using existing, accepted technologies (e.g. ADCP). The outcome is better constraint and extension of rating curves

  17. Correlation of volumetric flow rate and skin blood flow with cold intolerance in digital replantation.

    Science.gov (United States)

    Zhao, Gang; Mi, Jingyi; Rui, Yongjun; Pan, Xiaoyun; Yao, Qun; Qiu, Yang

    2017-12-01

    Cold intolerance is a common complication of digital replantation. The exact etiology is unclear, but it is considered to be multifactorial, including nonsurgical characteristics, vascular, and neurologic conditions. Blood flow may play a significant role in cold intolerance. This study was designed to evaluate the correlation of digital blood flow, including volumetric flow rate (VFR) and skin blood flow (SkBF), with cold intolerance in replanted fingers.A retrospective study was conducted among patients who underwent digital replantation between 2010 and 2013. Patients were selected into study cohort based on the inclusion criteria. Surgical data was collected on each patient, including age, sex, injury mechanism, amputation level, ischemia time, number of arteries repaired, and whether or not vascular crisis occurred. Patients were included as study cohort with both nerves repaired and without chronic disease. Cold intolerance was defined as a Cold Intolerance Symptom Severity (CISS) score over 30. The arterial flow velocity and caliber were measured by Color Doppler Ultrasound and the digital VFR was calculated. The SkBF was measured by Laser Speckle Imager. Both VFR and SkBF were calculated as a percentage of the contralateral fingers. Comparative study of surgical data and blood flow was performed between the patient with and without cold intolerance. Correlation between VFR and SkBF was also analyzed.A total of 93 patients met inclusion criteria for the study. Approximately, 42 patients were identified as having cold intolerance. Fingers that survived vascular crisis had a higher incidence of cold intolerance with a lower VFR and SkBF. The VFR was higher in 2-artery replantation, but the SkBF and incidence of cold intolerance did not differ significantly. No differences were found in age, sex, injury mechanism, amputation level, or ischemia time. Furthermore, no correlation was found between VFR and SkBF.Cold intolerance of digital replantation is associated

  18. Effect of inspiratory flow rate on the efficiency of carbon dioxide removal at tidal volumes below instrumental dead space.

    Science.gov (United States)

    Hurley, Edward H; Keszler, Martin

    2017-03-01

    The ability to ventilate babies with tidal volumes (VTs) below dead space has been demonstrated both in vivo and in vitro, though it appears to violate classical respiratory physiology. We hypothesised that this phenomenon is made possible by rapid flow of gas that penetrates the dead space allowing fresh gas to reach the lungs and that the magnitude of this phenomenon is affected by flow rate or how rapidly air flows through the endotracheal tube. We conducted two bench experiments. First, we measured the time needed for complete CO2 washout from a test lung to assess how fixed VT but different inflation flow rates affect ventilation. For the second experiment, we infused carbon dioxide at a low rate into the test lung, varied the inflation flow rate and adjusted the VT to maintain stable end tidal carbon dioxide (ETCO2). At all tested VTs, lower flow rate increased the time it took for CO2 to washout from the test lung. The effect was most pronounced for VTs below dead space. The CO2 steady-state experiment showed that ETCO2 increased when the flow rate decreased. Ventilating with a slower flow rate required a nearly 20% increase in VT for the same effective alveolar ventilation. Inflation flow rate affects the efficiency of CO2 removal with low VT. Our results are relevant for providers using volume-controlled ventilation or other modes that use low inflation flow rates because the VT required for normocapnia will be higher than published values that were generated using pressure-limited ventilation modes with high inflation flows. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  19. Energy transfer model and its applications of ultrasonic gas flow-meter under static and dynamic flow rates.

    Science.gov (United States)

    Fang, Min; Xu, Ke-Jun; Zhu, Wen-Jiao; Shen, Zi-Wen

    2016-01-01

    Most of the ultrasonic gas flow-meters measure the gas flow rate by calculating the ultrasonic transmission time difference between the downstream and upstream. Ultrasonic energy attenuation occurs in the processes of the ultrasonic generation, conversion, transmission, and reception. Additionally, at the same time, the gas flow will also affect the ultrasonic propagation during the measurement, which results in the ultrasonic energy attenuation and the offset of ultrasonic propagation path. Thus, the ultrasonic energy received by the transducer is weaker. When the gas flow rate increases, this effect becomes more apparent. It leads to the measurement accuracy reduced, and the measurement range narrowed. An energy transfer model, where the ultrasonic gas flow-meter under without/with the gas flow, is established by adopting the statistical analysis and curve fitting based on a large amount of experimental data. The static sub model without the gas flow expresses the energy conversion efficiency of ultrasonic gas transducers, and the dynamic sub model with the gas flow reflects the energy attenuation pattern following the flow rate variations. The mathematical model can be used to determine the minimum energy of the excitation signal for meeting the requirement of specific measurement range, and predict the maximum measurable flow rate in the case of fixed energy of excitation signal. Based on the above studies, a method to enhance the excitation signal energy is proposed under the output power of the transmitting circuit being a finite value so as to extend the measurement rage of ultrasonic gas flow-meter.

  20. High Strain Rate Characterisation of Composite Materials

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Normann Wilken

    -reinforced polymers, were considered, and it was first shown that the loading history controls equilibrium process. Then the High-speed servo-hydraulic test machine was analysed in terms its ability to create a state of constant strain rate in the specimen. The invertible inertial forces in the load train prevented...... a linear elastic specimen to reach a state of constant strain rate before fracture. This was in contrast to ductile materials, which are widely tested with for the High-speed servohydraulic test machine. The development of the analysis and the interpretation of the results, were based on the experience...... from designing and constructing a high-speed servo-hydraulic test machine and by performing a comprehensive test series. The difficulties encountered in the test work could be addressed with the developed analysis. The conclusion was that the High-speed servo-hydraulic test machine is less suited...

  1. Effects of Purge-Flow Rate on Microbubble Capture in Radial Arterial-Line Filters

    Science.gov (United States)

    Herbst, Daniel P.

    2016-01-01

    Abstract: The process of microbubble filtration from blood is complex and highly dependent on the forces of flow and buoyancy. To protect the patient from air emboli, arterial-line filters commonly use a micropore screen, a large volume housing with purpose-built shape, and a purge port to trap, separate, and remove circulating microbubbles. Although it has been proposed that an insufficient buoyancy force renders the purge port ineffective at removing microbubbles smaller than 500 μm, this research attempts to investigate the purge flow of an arterial-line filter to better understand the microbubble removal function in a typical radial filter design. As its primary objective, the study aims to determine the effect of purge-flow rate on bubble capture using air bolus injections from a syringe pump with 22-gauge needle and Doppler ultrasound bubble detection. The measureable bubble size generated in the test circuit ranged between 30 and 500 μm, while purge flow was varied between .1 and .5 L/min for testing. Statistical analysis of the test data was handled using a repeated measures design with significance set at p bubble counts, but the effect of purge-flow rate on bubble capture decreased as bubble size increased. Results also showed that purge flow from the test filter was capable of capturing all bubble sizes being generated over the entire flow range tested, and confirms utility of the purge port in removing microbubbles smaller than 500 μm. By analyzing bubble counts in the purge flow of a typical radial-filter design, this study demonstrates that currently available micropore filter technology is capable of removing the size range of bubbles that commonly pass through modern pump-oxygenator systems and should continue to be considered during extracorporeal circulation as a measure to improve patient safety. PMID:27729703

  2. Effects of Purge-Flow Rate on Microbubble Capture in Radial Arterial-Line Filters.

    Science.gov (United States)

    Herbst, Daniel P

    2016-09-01

    The process of microbubble filtration from blood is complex and highly dependent on the forces of flow and buoyancy. To protect the patient from air emboli, arterial-line filters commonly use a micropore screen, a large volume housing with purpose-built shape, and a purge port to trap, separate, and remove circulating microbubbles. Although it has been proposed that an insufficient buoyancy force renders the purge port ineffective at removing microbubbles smaller than 500 μm, this research attempts to investigate the purge flow of an arterial-line filter to better understand the microbubble removal function in a typical radial filter design. As its primary objective, the study aims to determine the effect of purge-flow rate on bubble capture using air bolus injections from a syringe pump with 22-gauge needle and Doppler ultrasound bubble detection. The measureable bubble size generated in the test circuit ranged between 30 and 500 μm, while purge flow was varied between .1 and .5 L/min for testing. Statistical analysis of the test data was handled using a repeated measures design with significance set at p bubble counts, but the effect of purge-flow rate on bubble capture decreased as bubble size increased. Results also showed that purge flow from the test filter was capable of capturing all bubble sizes being generated over the entire flow range tested, and confirms utility of the purge port in removing microbubbles smaller than 500 μm. By analyzing bubble counts in the purge flow of a typical radial-filter design, this study demonstrates that currently available micropore filter technology is capable of removing the size range of bubbles that commonly pass through modern pump-oxygenator systems and should continue to be considered during extracorporeal circulation as a measure to improve patient safety.

  3. High resolution measurement of the glycolytic rate

    Directory of Open Access Journals (Sweden)

    Carla X Bittner

    2010-09-01

    Full Text Available The glycolytic rate is sensitive to physiological activity, hormones, stress, aging and malignant transformation. Standard techniques to measure the glycolytic rate are based on radioactive isotopes, are not able to resolve single cells and have poor temporal resolution, limitations that hamper the study of energy metabolism in the brain and other organs. A new method is described in this article, which makes use of a recently-developed FRET glucose nanosensor to measure the rate of glycolysis in single cells with high temporal resolution. Used in cultured astrocytes, the method showed for the first time that glycolysis can be activated within seconds by a combination of glutamate and K+, supporting a role for astrocytes in neurometabolic and neurovascular coupling in the brain. It was also possible to make a direct comparison of metabolism in neurons and astrocytes lying in close proximity, paving the way to a high-resolution characterization of brain energy metabolism. Single-cell glycolytic rates were also measured in fibroblasts, adipocytes, myoblasts and tumor cells, showing higher rates for undifferentiated cells and significant metabolic heterogeneity within cell types. This method should facilitate the investigation of tissue metabolism at the single-cell level and is readily adaptable for high-throughput analysis.

  4. High Rate Performing Li-ion Battery

    Science.gov (United States)

    2015-02-09

    permeable to lithium ions and efficient in transferring the electrons into/from the LVP surface to the corresponding current collector. a) b) c) d) e...PO4)3/C for High Rate Lithium-ion Battery Applications”, Lee Hwang Sheng, Nail Suleimanov, Vishwanathan Ramar, Mangayarkarasi Murugan, Kuppan

  5. Concomitant chemoradiotherapy with high dose rate brachytherapy ...

    African Journals Online (AJOL)

    Purpose: This study aims to report the incidence of treatment-induced acute toxicities, local control and survival of patients with cervix cancer treated by external beam radiotherapy (EBR) and high-dose-rate (HDR) brachytherapy concomitant with weekly Cisplatin chemotherapy. Methods: Forty patients with FIGO Stages IB2 ...

  6. A COMPREHENSIVE STUDY OF HOURLY AND DAILY SEWAGE FLOW RATES IN FLORIDA PUBLIC SCHOOLS.

    Science.gov (United States)

    FOGARTY, WILLIAM J.; REEDER, MILTON E.

    A DETERMINATION OF THE HOURLY AND DAILY SEWAGE FLOW RATES IN FLORIDA PUBLIC SCHOOLS WAS MADE TO IDENTIFY THE FLOW CHARACTERISTICS AND TO PROVIDE A MORE PRECISE BASIS FOR THE ESTABLISHMENT OF DESIGN CRITERIA FOR SEWAGE DISPOSAL FACILITIES IN SCHOOLS. WATER FLOW DATA WAS COLLECTED FOR 158 SCHOOLS AND SEWAGE FLOW DATA FROM 42 SCHOOLS. THE FINDINGS…

  7. High strain rate behaviour of polypropylene microfoams

    Directory of Open Access Journals (Sweden)

    Martínez A.B.

    2012-08-01

    Full Text Available Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc. or personal safety (helmets, knee-pads, etc.. In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s−1 in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB. Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  8. High strain rate behaviour of polypropylene microfoams

    Science.gov (United States)

    Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.

    2012-08-01

    Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc.) or personal safety (helmets, knee-pads, etc.). In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry) is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  9. Monitoring nano-flow rate of water by atomic emission detection using helium radio-frequency plasma.

    Science.gov (United States)

    Nakagama, Tatsuro; Maeda, Tsuneaki; Uchiyama, Katsumi; Hobo, Toshiyuki

    2003-06-01

    Recently, high-performance nano-scale flow pumping systems have been developed for micro and miniaturized analysis systems. A novel device capable of measuring and monitoring nanoliter scale flow rates has been required for the further development of the pumping system. In this study, an atomic emission detector using helium radio-frequency plasma (RFP-AED) was used for the measurement of the nanoliter scale flow rate of water by quantitatively detecting the emission from hydrogen in the water molecules. Monitoring nano-flow rates of water in the range up to 1.0 microl min(-1), and the change in the flow rate by the indication of the ratio of the emissions of H (656.3 nm) and He (667.8 nm) were successful. At present, the lowest flow rate that could be determined reproducibly was 4 nl min(-1) calculated as five times the standard deviation of the background noise. Additionally, similar evaluations for the deviation of each flow rate by using the RFP-AED and a flow-injection system were produced.

  10. Effect of flow rate and concentration difference on reverse electrodialysis system

    Science.gov (United States)

    Kwon, Kilsugn; Han, Jaesuk; Kim, Daejoong

    2013-11-01

    Various energy conversion technologies have been developed to reduce dependency on limited fossil fuels, including wind power, solar power, hydropower, ocean power, and geothermal power. Among them, reverse electrodialysis (RED), which is one type of salinity gradient power (SGP), has received much attention due to high reliability and simplicity without moving parts. Here, we experimentally evaluated the RED performance with several parameters like flow rate of concentrated and dilute solution, concentration difference, and temperature. RED was composed of endplates, electrodes, spacers, anion exchange membrane, and cation exchange membrane. Endplates are made by a polypropylene. It included the electrodes, flow field for the electrode rinse solution, and path to supply a concentrated and dilute solution. Titanium coated by iridium and ruthenium was used as the electrode. The electrode rinse solution based on hexacyanoferrate system is used to reduce the power loss generated by conversion process form ionic current to electric current. Maximum power monotonously increases as increasing flow rate and concentration difference. Net power has optimal point because pumping power consumption increases with flow rate. This work was supported by Basic Science Research Program (Grat No. NRF-2011-0009993) through the National Research Foundation of Korea.

  11. High-Rate Capable Floating Strip Micromegas

    Science.gov (United States)

    Bortfeldt, Jonathan; Bender, Michael; Biebel, Otmar; Danger, Helge; Flierl, Bernhard; Hertenberger, Ralf; Lösel, Philipp; Moll, Samuel; Parodi, Katia; Rinaldi, Ilaria; Ruschke, Alexander; Zibell, André

    2016-04-01

    We report on the optimization of discharge insensitive floating strip Micromegas (MICRO-MEsh GASeous) detectors, fit for use in high-energy muon spectrometers. The suitability of these detectors for particle tracking is shown in high-background environments and at very high particle fluxes up to 60 MHz/cm2. Measurement and simulation of the microscopic discharge behavior have demonstrated the excellent discharge tolerance. A floating strip Micromegas with an active area of 48 cm × 50 cm with 1920 copper anode strips exhibits in 120 GeV pion beams a spatial resolution of 50 μm at detection efficiencies above 95%. Pulse height, spatial resolution and detection efficiency are homogeneous over the detector. Reconstruction of particle track inclination in a single detector plane is discussed, optimum angular resolutions below 5° are observed. Systematic deviations of this μTPC-method are fully understood. The reconstruction capabilities for minimum ionizing muons are investigated in a 6.4 cm × 6.4 cm floating strip Micromegas under intense background irradiation of the whole active area with 20 MeV protons at a rate of 550 kHz. The spatial resolution for muons is not distorted by space charge effects. A 6.4 cm × 6.4 cm floating strip Micromegas doublet with low material budget is investigated in highly ionizing proton and carbon ion beams at particle rates between 2 MHz and 2 GHz. Stable operation up to the highest rates is observed, spatial resolution, detection efficiencies, the multi-hit and high-rate capability are discussed.

  12. Unstimulated salivary flow rate, pH and buffer capacity of saliva in healthy volunteers.

    Science.gov (United States)

    Fenoll-Palomares, C; Muñoz Montagud, J V; Sanchiz, V; Herreros, B; Hernández, V; Mínguez, M; Benages, A

    2004-11-01

    To assess the salivary flow rate, pH, and buffer capacity of healthy volunteers, and their relationships with age, gender, obesity, smoking, and alcohol consumption, and to establish the lower-end value of normal salivary flow (oligosialia). A prospective study was conducted in 159 healthy volunteers (age > 18 years, absence of medical conditions that could decrease salivary flow). Unstimulated whole saliva was collected during ten minutes, and salivary flow rate (ml/min), pH, and bicarbonate concentration (mmol/l) were measured using a Radiometer ABL 520. The 5 percentile of salivary flow rate and bicarbonate concentration was considered the lower limit of normality. Median salivary flow rate was 0.48 ml/min (range: 0.1-2 ml/min). Age younger than 44 years was associated with higher flow rates (OR 2.10). Compared with women, men presented a higher flow rate (OR 3.19) and buffer capacity (OR 2.81). Bicarbonate concentration correlated with salivary flow rate. The lower-end values of normal flow rate and bicarbonate concentration were 0.15 ml/min and 1.800 mmol/l, respectively. The presence of obesity, smoking, and alcohol consumption did not influence salivary parameters. In healthy volunteers, salivary flow rate depends on age and gender, and correlates with buffer capacity. Obesity, smoking, and alcohol use do not influence salivary secretion.

  13. In vitro validation of endovascular Doppler-derived flow rates in models of the cerebral circulation.

    Science.gov (United States)

    McGah, P M; Nerva, J D; Morton, R P; Barbour, M C; Levitt, M R; Mourad, P D; Kim, L J; Aliseda, A

    2015-11-01

    This study presents validation of endovascular Doppler velocimetry-based volumetric flow rate measurements conducted in a pulsatile flow loop simulating conditions in both the internal carotid and basilar artery. In vitro models of cerebral vessels, each containing an aneurysm, were fabricated from patient anatomies extracted from 3D rotational angiography. Flow velocity measurements were collected with three different experimental techniques: an endovascular Doppler wire, Particle Image Velocimetry, and a time-resolved ultrasonic flow meter. Womersley's theory of pulsatile flow in a cylindrical vessel was used to compute time-resolved volumetric flow rates from the endovascular Doppler velocity. The volumetric flow rates computed from the Doppler measurements were compared to those from the Particle Image Velocimetry profile measurements, and the direct measurements from the ultrasonic flow meter. The study establishes confidence intervals for any systematic or random errors associated with the wire-derived flow rates as benchmarked to the other two modalities. There is an approximately 10% random error in the Doppler-derived peak and time-averaged flow rates. There is a measurable uniform bias, about 15% too low, in the time-averaged Doppler-derived flow rates. There is also a small proportional bias in the peak systolic Doppler-derived flow rates. Potential sources of error are also discussed.

  14. Measurement of retinal blood flow rate in diabetic rats: disparity between techniques due to redistribution of flow.

    Science.gov (United States)

    Leskova, Wendy; Watts, Megan N; Carter, Patsy R; Eshaq, Randa S; Harris, Norman R

    2013-04-26

    Reports of altered retinal blood flow in experimental models of type I diabetes have provided contrasting results, which leads to some confusion as to whether flow is increased or decreased. The purpose of our study was to evaluate early diabetes-induced changes in retinal blood flow in diabetic rats, using two distinctly different methods. Diabetes was induced by injection of streptozotocin (STZ), and retinal blood flow rate was measured under anesthesia by a microsphere infusion technique, or by an index of flow based on the mean circulation time between arterioles and venules. Measurements in STZ rats were compared to age-matched nondiabetic controls. In addition, the retinal distribution of fluorescently-labeled red blood cells (RBCs) was viewed by confocal microscopy in excised flat mounts. Retinal blood flow rate was found to decrease by approximately 33% in the STZ rats compared to controls (P contrast, the mean circulation time through the retina was found to be almost 3× faster in the STZ rats (P < 0.01). This contradiction could be explained by flow redistribution through the superficial vessels of the diabetic retina, with this possibility supported by our observation of significantly fewer RBCs flowing through the deeper capillaries. We conclude that retinal blood flow rate is reduced significantly in the diabetic rat, with a substantial decrease of flow through the capillaries due to shunting of blood through the superficial layer, allowing rapid transit from arterioles to venules.

  15. Study on solid-liquid two-phase unsteady flow characteristics with different flow rates in screw centrifugal pump

    Science.gov (United States)

    Li, R. N.; Y Wang, H.; Han, W.; Ma, W.; Shen, Z. J.

    2013-12-01

    The screw centrifugal pump is used as an object, and the unsteady numerical simulation of solid-liquid two-phase flow is carried out under different flow rate conditions in one circle by choosing the two-phase flow of sand and water as medium, using the software FLUENT based on the URANS equations, combining with sliding mesh method, and choosing the Mixture multiphase flow model and the SIMPLE algorithm. The results show that, with the flow rate increasing, the change trends for the pressure on volute outlet are almost constant, the fluctuation trends of the impeller axial force have a little change, the pressure and the axial force turn to decrease on the whole, the radial force gradually increases when the impeller maximum radius passes by half a cycle near the volute outlet, and the radial force gradually decreases when the maximum radius passes by the other half a cycle in a rotation cycle. The distributions of the solid particles are very uneven under a small flow rate condition on the face. The solid particles under a big flow rate condition are distributed more evenly than the ones under a small flow rate condition on the back. The theoretical basis and reference are provided for improving its working performance.

  16. An experimental setup for traceable measurement and calibration of liquid flow rates down to 5 nl/min.

    Science.gov (United States)

    Ahrens, Martin; Nestler, Bodo; Klein, Stephan; Lucas, Peter; Petter, Harm Tido; Damiani, Christian

    2015-08-01

    This work presents the improvements of an experimental setup for measuring ultra-low flow rates down to 5 nl/min. The system uses a telecentric CCD imaging system mounted on a high-precision, computer-controlled linear stage to track a moving liquid meniscus inside a glass capillary. Compared to the original setup, the lowest attainable expanded uncertainty at any flow rate has been reduced from 5.4% to 2%. In addition, the conformity with specification of three commercial micro-fluidic devices was evaluated using the new setup: one syringe pump, one implantable infusion pump and one thermal flow sensor. The flow sensor and the implantable infusion pump met the compliance criteria (coverage probability 95%). The syringe pump however, failed to meet the specifications at 5 nl/min and 10 nl/min. No assessment could be made at higher flow rates.

  17. High strain rate deformation of layered nanocomposites

    Science.gov (United States)

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P.; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A.; Thomas, Edwin L.

    2012-11-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  18. Relationship between salivary immunoglobulin a, lactoferrin and lysozyme flow rates and lifestyle factors in Japanese children: a cross-sectional study.

    Science.gov (United States)

    Ide, Momo; Saruta, Juri; To, Masahiro; Yamamoto, Yuko; Sugimoto, Masahiro; Fuchida, Shinya; Yokoyama, Mina; Kimoto, Shigenari; Tsukinoki, Keiichi

    2016-10-01

    The antimicrobial substances in saliva contribute to the maintenance of both oral health and overall health of the body. Therefore, the associations among immunoglobulin A (IgA), lactoferrin and lysozyme flow rates in the saliva of children, and their relationships with the physical attributes and lifestyle factors of children, were examined. Saliva was collected from 90 children who visited the Kanagawa Dental University Hospital Pediatric Dentistry, and questionnaires were completed by guardians. IgA, lactoferrin and lysozyme concentrations were measured in the saliva samples using enzyme-linked immunosorbent assays (ELISAs). The IgA flow rate in saliva increased as age, height and weight increased. A correlation was found between lactoferrin and lysozyme flow rates. When the antimicrobial substance flow rates in the saliva were divided into two groups of 22 children each based on the highest and lowest quartiles, children with either a low or high IgA flow rate also had a high or low lactoferrin flow rate, respectively. The same pattern was observed for lactoferrin and lysozyme flow rates. There is a high probability that the IgA flow rate in the saliva of children reflects and corresponds to the developmental status of immune function as the child ages and increases in height and weight. The flow rates of lactoferrin and lysozyme were correlated in children. In addition, regarding lifestyle factors, the duration of sleep and lactoferrin flow rate were also related.

  19. A comprehensive model to determine the effects of temperature and species fluctuations on reaction rates in turbulent reacting flows

    Science.gov (United States)

    Chinitz, W.

    1986-01-01

    A computationally-viable model describing the interaction between fluid-mechanical turbulence and finite-rate combustion reactions, principally in high-speed flows was developed. Chemical kinetic mechanisms, complete and global, were developed describing the finite rate reaction of fuels of interest to NASA. These fuels included principally hydrogen and silane, although a limited amount of work involved hydrocarbon fuels as well.

  20. High rate flame synthesis of highly crystalline iron oxide nanorods

    Science.gov (United States)

    Merchan-Merchan, W.; Saveliev, A. V.; Taylor, A. M.

    2008-03-01

    Single-step flame synthesis of iron oxide nanorods is performed using iron probes inserted into an opposed-flow methane oxy-flame. The high temperature reacting environment of the flame tends to convert elemental iron into a high density layer of iron oxide nanorods. The diameters of the iron oxide nanorods vary from 10 to 100 nm with a typical length of a few microns. The structural characterization performed shows that nanorods possess a highly ordered crystalline structure with parameters corresponding to cubic magnetite (Fe3O4) with the [100] direction oriented along the nanorod axis. Structural variations of straight nanorods such as bends, and T-branched and Y-branched shapes are frequently observed within the nanomaterials formed, opening pathways for synthesis of multidimensional, interconnected networks.

  1. Successful treatment of high-flow priapism with radiologic ...

    African Journals Online (AJOL)

    occlusive, low flow) painful priapism and nonischemic (arterial, high flow) painless priapism.. We report our successful treatment of arterial priapism by means of radiologic selective transcatheter embolization of the internal pudendal artery using micro ...

  2. Heating capabilities of the Hotline and Autoline at low flow rates.

    Science.gov (United States)

    Schnoor, Joerg; Weber, Ingo; Macko, Stephan; Heussen, Nicole; Rossaint, Rolf

    2006-04-01

    At low flow rates, fluid warmers using coaxial warming tubes are superior in preventing heat loss. This laboratory investigation was performed in order to compare the heating capabilities of two coaxial fluid warmers. The Hotline and the Autoline were investigated by using normal saline at various flow rates (10-99 ml x h(-1)). Final infusion temperatures were measured six times in a row at the end of the tubing by using a rapid-response thermometer. Final temperatures were compared with those of infusions, which passed through disposable i.v. tubing covered and warmed using an 'off label' convective air warming system (WarmTouch). Measurements were performed at two different room temperatures (20 and 24 degrees C). Each group was analyzed with respect to differences between various flow rates as well as differences between the groups at comparable flow rates by using a three-way anova with multiple comparisons according to Tukey's procedure. Significance was defined at P flow rates efficiently above 34 degrees C, with the Hotline being more effective than the Autoline (P flow rates (10-60 and 80 ml x h(-1)), the Autoline demonstrated lower infusion temperatures throughout elevated room temperature at flow rates between 20 and 90 ml x h(-1). Both devices heated infusions more efficiently compared with 'off label used' convective air warmer (each with P flow rates. However, the heating capability of the Hotline was superior and can further be increased at low flow rates by increasing the room temperature.

  3. High performance micro-flow cytometer based on optical fibres.

    Science.gov (United States)

    Etcheverry, S; Faridi, A; Ramachandraiah, H; Kumar, T; Margulis, W; Laurell, F; Russom, A

    2017-07-17

    Flow cytometry is currently the gold standard for analysis of cells in the medical laboratory and biomedical research. Fuelled by the need of point-of-care diagnosis, a significant effort has been made to miniaturize and reduce cost of flow cytometers. However, despite recent advances, current microsystems remain less versatile and much slower than their large-scale counterparts. In this work, an all-silica fibre microflow cytometer is presented that measures fluorescence and scattering from particles and cells. It integrates cell transport in circular capillaries and light delivery by optical fibres. Single-stream cell focusing is performed by Elasto-inertial microfluidics to guarantee accurate and sensitive detection. The capability of this technique is extended to high flow rates (up to 800 µl/min), enabling a throughput of 2500 particles/s. The robust, portable and low-cost system described here could be the basis for a point-of-care flow cytometer with a performance comparable to commercial systems.

  4. [The Effect of Dialysate Flow Rate on Dialysis Adequacy and Fatigue in Hemodialysis Patients].

    Science.gov (United States)

    Cha, Sun Mi; Min, Hye Sook

    2016-10-01

    In this single repeated measures study, an examination was done on the effects of dialysate flow rate on dialysis adequacy and fatigue in patients receiving hemodialysis. This study was a prospective single center study in which repeated measures analysis of variance were used to compare Kt/V urea (Kt/V) and urea reduction ratio (URR) as dialysis adequacy measures and level of fatigue at different dialysate flow rates: twice as fast as the participant's own blood flow, 500 mL/min, and 700 mL/min. Thirty-seven hemodialysis patients received all three dialysate flow rates using counterbalancing. The Kt/V (M±SD) was 1.40±0.25 at twice the blood flow rate, 1.41±0.23 at 500 mL/min, and 1.46±0.24 at 700 mL/min. The URR (M±SD) was 68.20±5.90 at twice the blood flow rate, 68.67±5.22 at 500 mL/min, and 70.11±5.13 at 700 mL/min. When dialysate flow rate was increased from twice the blood flow rate to 700 mL/min and from 500 mL/min to 700 mL/min, Kt/V and URR showed relative gains. There was no difference in fatigue according to dialysate flow rate. Increasing the dialysate flow rate to 700 mL/min is associated with a significant nicrease in dialysis adequacy. Hemodialysis with a dialysate flow rate of 700 mL/min should be considered in selected patients not achieving adequacy despite extended treatment times and optimized blood flow rate.

  5. Flow “Fine” Synthesis: High Yielding and Selective Organic Synthesis by Flow Methods

    Science.gov (United States)

    2015-01-01

    Abstract The concept of flow “fine” synthesis, that is, high yielding and selective organic synthesis by flow methods, is described. Some examples of flow “fine” synthesis of natural products and APIs are discussed. Flow methods have several advantages over batch methods in terms of environmental compatibility, efficiency, and safety. However, synthesis by flow methods is more difficult than synthesis by batch methods. Indeed, it has been considered that synthesis by flow methods can be applicable for the production of simple gasses but that it is difficult to apply to the synthesis of complex molecules such as natural products and APIs. Therefore, organic synthesis of such complex molecules has been conducted by batch methods. On the other hand, syntheses and reactions that attain high yields and high selectivities by flow methods are increasingly reported. Flow methods are leading candidates for the next generation of manufacturing methods that can mitigate environmental concerns toward sustainable society. PMID:26337828

  6. High dose rate brachytherapy for oral cancer

    Science.gov (United States)

    YamazakI, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Furukawa, Souhei; Koizumi, Masahiko; Ogawa, Kazuhiko

    2013-01-01

    Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer. PMID:23179377

  7. Litter ammonia losses amplified by higher air flow rates

    Science.gov (United States)

    ABSTRACT Broiler litter utilization has largely been associated with land application as fertilizer. Reducing ammonia (NH3) released from litter enhances its fertilizer value and negates detrimental impacts to the environment. A laboratory study was conducted to quantify the effect of air flow var...

  8. Behavior of free surface vortices in cylindrical vessel under fluctuating flow rate

    Energy Technology Data Exchange (ETDEWEB)

    Hideaki Monji; Toshinori Akimoto; Daisuke Miwa [Graduate School of System and Information Engineering University of Tsukuba Tsukuba 305-8573 (Japan); Hideaki Kamide [New Thechnology Development Group, Advanced Technology Division O-arai Engineering Center, Japan Nucler Cycle Development Institute O-arai 311-1393 (Japan)

    2005-07-01

    Full text of publication follows: This paper deals with characteristics of free surface vortices at an upper plenum in a Fast Breeder Reactor. The free surface vortex is one of the most important mechanisms causing gas entrainment. Because the gas entrainment affects on reactivity of the reactor, the estimation of the onset condition of gas entrainment is an important factor for design of the reactor. The gas entrainment due to the free surface vortex is a time series phenomena; (i) formation of a vortex dimple on the free surface, (ii) development of the gas core of the vortex by a downward flow, and (iii) gas entrainment by the separation of bubbles at a tip of the gas core. In this study, the gas entrainment by the bubble separation is focused on and the unsteady behavior of the gas core by the fluctuations of the flow conditions is investigated experimentally. In the experiment, the free surface vortex was generated in a cylindrical vessel with a tangential slit injection and the downward flow was by a suction pipe at the bottom. The working fluid was water and the vessel is under the atmospheric air. The gas core developed due to the circulating and downward flow. In order to know the unsteady behavior of the gas core, the injection flow rate into the vessel was changed as a sine wave, and the time series of the gas core geometry was measured by a stereo image processing. The results of the study are mainly as follows; (i) The gas core length changed with the water flow rate but the shape of the fluctuation of gas core length was not a sine wave. The core length decreased suddenly when the water flow rate decreased. This corresponds that the characteristic time of the flow for the increasing flow rate is longer than that for the decreasing flow rate. (ii) The gas core length under the fluctuating flow rate was shorter than that under the condition of the fixed water flow rate which is the same as the maximum water flow rate of the fluctuating flow. This fact

  9. High speed flow cytometric separation of viable cells

    Science.gov (United States)

    Sasaki, Dennis T.; Van den Engh, Gerrit J.; Buckie, Anne-Marie

    1995-01-01

    Hematopoietic cell populations are separated to provide cell sets and subsets as viable cells with high purity and high yields, based on the number of original cells present in the mixture. High-speed flow cytometry is employed using light characteristics of the cells to separate the cells, where high flow speeds are used to reduce the sorting time.

  10. Measurement of Air Flow Rate in a Naturally Ventilated Double Skin Facade

    DEFF Research Database (Denmark)

    Kalyanova, Olena; Jensen, Rasmus Lund; Heiselberg, Per

    2007-01-01

    Air flow rate in a naturally ventilated space is extremely difficult to measure due to the stochastic nature of wind, and as a consequence non-uniform and dynamic flow conditions. This paper describes three different methods to measure the air flow in a full-scale outdoor test facility with a nat...

  11. Economic method for measuring ultra-low flow rates of fluids

    Science.gov (United States)

    Bogdanovic, J. A.; Keller, W. F.

    1970-01-01

    Capillary tube flowmeter measures ultra-low flows of very corrosive fluids /such as chlorine trifluoride and liquid fluorine/ and other liquids with reasonable accuracy. Flowmeter utilizes differential pressure transducer and operates on the principle that for laminar flow in the tube, pressure drop is proportional to flow rate.

  12. Unsteady Flow Simulation of High-speed Turbopumps

    Science.gov (United States)

    Kiris, Cetin C.; Kwak, dochan; Chan, William; Housman, Jeffrey A.

    2006-01-01

    Computation of high-speed hydrodynamics requires high-fidelity simulation to resolve flow features involving transient flow, cavitation, tip vortex and multiple scales of unsteady fluctuations. One example of this type in aerospace is related to liquid-fueled rocket turbopump. Rocket turbopumps operate under severe conditions at very high rotational speeds typically at thousands of rpm. For example, the Shuttle orbiter low-pressure-fuel-turbopump creates transient flow features associated with reverse flows, tip clearance effects, secondary flows, vortex shedding, junction flows, and cavitation effects. Flow unsteadiness originating from the orbiter Low-Pressure-Fuel-Turbopump (LPFTP) inducer is one of the major contributors to the high frequency cyclic loading that results in high cycle fatigue damage to the flow liners just upstream of the LPFTP. The reverse flow generated at the tip of the inducer blades travels upstream and interacts with the bellows cavity. Simulation procedure for this type high-speed hydrodynamic problems requires a method for quantifying multi-scale and multi-phase flow as well as an efficient high-end computing strategy. The current paper presents a high-fidelity computational procedure for unsteady hydrodynamic problems using a high-speed liquid-fueled rocket turbopump.

  13. High-energy, high-rate materials processing

    Science.gov (United States)

    Marcus, H. L.; Bourell, D. L.; Eliezer, Z.; Persad, C.; Weldon, W.

    1987-12-01

    The increasingly available range of pulsed-power, high energy kinetic storage devices, such as low-inductance pulse-forming networks, compulsators, and homopolar generators, is presently considered as a basis for industrial high energy/high rate (HEHR) processing to accomplish shock hardening, drilling, rapid surface alloying and melting, welding and cutting, transformation hardening, and cladding and surface melting in metallic materials. Time-temperature-transformation concepts furnish the basis for a fundamental understanding of the potential advantages of this direct pulsed power processing. Attention is given to the HEHR processing of a refractory molybdenum alloy, a nickel-base metallic glass, tungsten, titanium aluminides, and metal-matrix composites.

  14. Operation of high rate microstrip gas chambers

    CERN Document Server

    Barr, A J; Bouclier, Roger; Capéans-Garrido, M; Dominik, Wojciech; Manzin, G; Million, Gilbert; Hoch, M; Ropelewski, Leszek; Sauli, Fabio; Sharma, A

    1996-01-01

    We describe recent measurements carried out in well controlled and reproducible conditions to help understanding the factors affecting the short and long term behaviour of Microstrip Gas Chambers. Special care has been taken concerning the gas purity and choice of materials used in the system and for the detectors construction. Detectors built on glasses with surface resistivity in the range $10^{13}-10^{15} \\Omega/\\Box$ have shown satisfactory performance as they do not show charging-up process at high rate and stand the large doses required for the future high luminosity experiments (~10 mC·cm-1·yr-1). Concerning the lifetime measurements, it has been observed that chambers manufactured on high-resistivity glass are far more susceptible of suffering ageing than detectors made on low resistivity, electron-conducting supports, independently of the metal used for the artwork (chromium or gold) at least in clean gas conditions. The successfully operation in the laboratory of detectors manufactured on diamond-...

  15. Real gas flows with high velocities

    CERN Document Server

    Lunev, Vladimir V

    2009-01-01

    Gasdynamic Model and Equations Outline of the Gasdynamic Model Basic Equations and Postulates Equations of State Kinetic Theory Second Law of Thermodynamics Speed of Sound Integral Equations of Motion Kinematics of Fluid Media Differential Equations of Gasdynamics Rheological Model Initial and Boundary Conditions Similarity and Modeling in Gasdynamics Euler Equations Navier-Stokes Equations Turbulent Flows Viscous and Inviscid Flow Models Inviscid Gasdynamics Stream Function, Potential,

  16. Normalizing parameters for the critical flow rate of simple fluids through nozzles

    Science.gov (United States)

    Hendricks, R. C.

    1974-01-01

    It is shown that two-phase critical nozzle flow of simple fluids almost obeys the principle of corresponding states. Quantum fluid departures from the principle are resolved as a function of temperature for para-hydrogen and helium. The critical flow rates are normalized, using a normalizing parameter for which the critical flow rates of all simple fluids reduce to a single isothermal curve. The expression obtained for the normalizing parameter is shown to provide good agreement with the experiment for the critical flow rates of nitrogen, oxygen, and para-hydrogen.

  17. Flow Rates in Liquid Chromatography, Gas Chromatography and Supercritical Fluid Chromatography: A Tool for Optimization

    Directory of Open Access Journals (Sweden)

    Joris Meurs

    2016-08-01

    Full Text Available This paper aimed to develop a standalone application for optimizing flow rates in liquid chromatography (LC, gas chromatography (GC and supercritical fluid chromatography (SFC. To do so, Van Deemter’s equation, Knox’ equation and Golay’s equation were implemented in a MATLAB script and subsequently a graphical user interface (GUI was created. The application will show the optimal flow rate or linear velocity and the corresponding plate height for the set input parameters. Furthermore, a plot will be shown in which the plate height is plotted against the linear flow velocity. Hence, this application will give optimized flow rates for any set conditions with minimal effort.

  18. Rate of coronary flow adaptation in response to changes in heart rate before and during anesthesia for coronary artery surgery

    NARCIS (Netherlands)

    van Wezel, H. B.; Kal, J. E.; Vergroesen, I.; Vroom, M. B.; de Graaf, R.; Dankelman, J.; Porsius, M.; Spaan, J. A.

    1996-01-01

    BACKGROUND: The rate of adaptation of coronary blood flow in response to stepwise changes in heart rate (HR) has been extensively studied in dogs and goats to improve our understanding of the dynamics of coronary regulation processes and their pathophysiology and to obtain time constants for

  19. Linear genetic programming for time-series modelling of daily flow rate

    Indian Academy of Sciences (India)

    In this study linear genetic programming (LGP), which is a variant of Genetic Programming, and two versions of Neural Networks (NNs) are used in predicting time-series of daily flow rates at a station on Schuylkill River at Berne, PA, USA. Daily flow rate at present is being predicted based on different time-series scenarios.

  20. Effect of Retarding Force on Mass Flow Rates of Fluid at Different ...

    African Journals Online (AJOL)

    ... mathematical model and software visualization to view the effect of retarding forces on the mass flow rate in term of visualization. C-sharp (C#) is the chosen program and this enable compares and us to determine the mass flow rates patterns in relation to retarding force in form of graphical tables at different temperature.

  1. Modeling Compressibility Effects in High-Speed Turbulent Flows

    Science.gov (United States)

    Sarkar, S.

    2004-01-01

    Man has strived to make objects fly faster, first from subsonic to supersonic and then to hypersonic speeds. Spacecraft and high-speed missiles routinely fly at hypersonic Mach numbers, M greater than 5. In defense applications, aircraft reach hypersonic speeds at high altitude and so may civilian aircraft in the future. Hypersonic flight, while presenting opportunities, has formidable challenges that have spurred vigorous research and development, mainly by NASA and the Air Force in the USA. Although NASP, the premier hypersonic concept of the eighties and early nineties, did not lead to flight demonstration, much basic research and technology development was possible. There is renewed interest in supersonic and hypersonic flight with the HyTech program of the Air Force and the Hyper-X program at NASA being examples of current thrusts in the field. At high-subsonic to supersonic speeds, fluid compressibility becomes increasingly important in the turbulent boundary layers and shear layers associated with the flow around aerospace vehicles. Changes in thermodynamic variables: density, temperature and pressure, interact strongly with the underlying vortical, turbulent flow. The ensuing changes to the flow may be qualitative such as shocks which have no incompressible counterpart, or quantitative such as the reduction of skin friction with Mach number, large heat transfer rates due to viscous heating, and the dramatic reduction of fuel/oxidant mixing at high convective Mach number. The peculiarities of compressible turbulence, so-called compressibility effects, have been reviewed by Fernholz and Finley. Predictions of aerodynamic performance in high-speed applications require accurate computational modeling of these "compressibility effects" on turbulence. During the course of the project we have made fundamental advances in modeling the pressure-strain correlation and developed a code to evaluate alternate turbulence models in the compressible shear layer.

  2. Drop-box Weir for Measuring Flow Rates Under Extreme Flow Conditions

    Science.gov (United States)

    Sediment and large rocks often are transported in runoff during extreme events. The sediment can deposit in a runoff-measuring structure and give erroneous readings. The drop-box weir (DBW) is one of only a few flow-measuring devices capable of measuring sediment-laden flows. Recent studies have ...

  3. Upgrade Strategy for ALICE at High Rate

    CERN Document Server

    Musa, L

    2012-01-01

    The longterm goal of the ALICE experiment is to provide a precise characterization of the Quark-Gluon Plasma (QGP) state. Such a determination of its properties including initial temperature, degrees of freedom, speed of sound, and in general, transport coefficients would be a major achievement. This would go a long way towards a better understanding of QCD as a genuine multi-particle theory. To achieve this goal, high statistics measurements are required, which will give access also to the very rare physics channels needed to understand the dynamics of this condensed phase of QCD. The general upgrade strategy for the ALICE central barrel is conceived to deal with this challenge with expected Pb-Pb interaction rates of up to 50 kHz, that would provide an accumulated sample of the order of 10 nb^-1 in the period 2019-2023. In this document we sketch the modifications/replacements needed in all ALICE central barrel detectors and online systems (Trigger, DAQ and HLT) for high luminosity running. As the ALICE for...

  4. Influence of transient strain rates on material flow stress and microstructure evolution

    Science.gov (United States)

    Dierdorf, Jens; Lohmar, Johannes; Hirt, Gerhard

    2017-10-01

    A comprehensive knowledge about the material flow stress is a key parameter for a reliable design of hot forming processes using Finite Element (FE) software codes. Due to the microstructure evolution caused by the interaction of hardening and softening phenomena that take place during hot forming operations, the material flow stress is influenced by strain rate and temperature. While transient strain rates and temperatures typically characterize the industrial forming processes, the flow curves used in FE simulations are normally determined at arbitrary constant temperatures and strain rates. To calculate the flow stress evolution in between the measured strain rates, FE programs use linear interpolation. Hence, the material relaxation behavior caused by the microstructure evolution during transient strain rates is not considered. Previous investigations by various authors have shown that for a rapid strain rate change by one order of magnitude significant deviations between measured flow stress and linear interpolation appear before the flow stress approximates the flow curve obtained at the new constant strain rate again. However as mentioned before, industrial forming processes are characterized by more or less smooth than instantaneous changes in strain rate. Therefore, in this study, changing strain rates with different linear slopes are investigated. For this purpose, isothermal cylinder compression tests of an industrial case hardening steel are conducted at elevated temperatures. The resulting flow stress is compared with the linear interpolation of the flow curves determined at constant strain rates. Additionally, the grain size evolution during the strain rate change is analyzed to better understand the microstructural changes. The current investigation shows that the slope of the strain rate increase significantly influences the deviation from the linear interpolation. This observation can be explained by the time dependent microstructure evolution

  5. On a sparse pressure-flow rate condensation of rigid circulation models.

    Science.gov (United States)

    Schiavazzi, D E; Hsia, T Y; Marsden, A L

    2016-07-26

    Cardiovascular simulation has shown potential value in clinical decision-making, providing a framework to assess changes in hemodynamics produced by physiological and surgical alterations. State-of-the-art predictions are provided by deterministic multiscale numerical approaches coupling 3D finite element Navier Stokes simulations to lumped parameter circulation models governed by ODEs. Development of next-generation stochastic multiscale models whose parameters can be learned from available clinical data under uncertainty constitutes a research challenge made more difficult by the high computational cost typically associated with the solution of these models. We present a methodology for constructing reduced representations that condense the behavior of 3D anatomical models using outlet pressure-flow polynomial surrogates, based on multiscale model solutions spanning several heart cycles. Relevance vector machine regression is compared with maximum likelihood estimation, showing that sparse pressure/flow rate approximations offer superior performance in producing working surrogate models to be included in lumped circulation networks. Sensitivities of outlets flow rates are also quantified through a Sobol׳ decomposition of their total variance encoded in the orthogonal polynomial expansion. Finally, we show that augmented lumped parameter models including the proposed surrogates accurately reproduce the response of multiscale models they were derived from. In particular, results are presented for models of the coronary circulation with closed loop boundary conditions and the abdominal aorta with open loop boundary conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. New approach to purging monitoring wells: Lower flow rates reduce required purging volumes and sample turbidity

    Energy Technology Data Exchange (ETDEWEB)

    Puls, R.W.

    1994-01-01

    It is generally accepted that monitoring wells must be purged to access formation water to obtain representative' ground water quality samples. Historically anywhere from 3 to 5 well casing volumes have been removed prior to sample collection to evacuate the standing well water and access the adjacent formation water. However, a common result of such purging practice is highly turbid samples from excessive downhole disturbance to the sampling zone. An alternative purging strategy has been proposed using pumps which permit much lower flow rates (<1 liter/min) and placement within the screened interval of the monitoring well. The advantages of this approach include increased spatial resolution of sampling points, less variability, less purge time (and volume), and low-turbidity samples. The overall objective is a more passive approach to sample extraction with the ideal approach being to match the intake velocity with the natural ground water flow velocity. The volume of water extracted to access formation water is generally independent of well size and capacity and dependant upon well construction, development, hydrogeologic variability and pump flow rate.

  7. Decomposition behavior of hemicellulose and lignin in the step-change flow rate liquid hot water.

    Science.gov (United States)

    Zhuang, Xinshu; Yu, Qiang; Wang, Wen; Qi, Wei; Wang, Qiong; Tan, Xuesong; Yuan, Zhenhong

    2012-09-01

    Hemicellulose and lignin are the main factors limiting accessibility of hydrolytic enzymes besides the crystallinity of cellulose. The decomposition behavior of hemicellulose and lignin in the step-change flow rate hot water system was investigated. Xylan removal increased from 64.53% for batch system (solid concentration 4.25% w/v, 18 min, 184°C) to 83.78% at high flow rates of 30 ml/min for 8 min, and then 10 ml/min for 10 min. Most of them (80-90%) were recovered as oligosaccharide. It was hypothesized that the flowing water could enhance the mass transfer to improve the sugars recovery. In addition, the solubilization mechanism of lignin in the liquid hot water was proposed according to the results of Fourier transform-infrared spectroscopy and scanning electron microscopy of the water-insoluble fraction and gas chromatography-mass spectrometry of the water-soluble fraction. It was proposed that lignin in the liquid hot water first migrated out of the cell wall in the form of molten bodies, and then flushed out of the reactor. A small quantity of them was further degraded into monomeric products such as vanillin, syringe aldehyde, coniferyl aldehyde, ferulic acid, and p-hydroxy-cinnamic acid. All of these observations would provide important information for the downstream processing, such as purification and concentration of sugars and the enzymatic digestion of residual solid.

  8. Flow visualization of bubble behavior under two-phase natural circulation flow conditions using high speed digital camera

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Wanderley F.; Su, Jian, E-mail: wlemos@con.ufrj.br, E-mail: sujian@lasme.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Faccini, Jose L.H., E-mail: faccini@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. de Termo-Hidraulica Experimental

    2013-07-01

    The The present work aims at identifying flow patterns and measuring interfacial parameters in two-phase natural circulation by using visualization technique with high-speed digital camera. The experiments were conducted in the Natural Circulation Circuit (CCN), installed at Nuclear Engineering Institute/CNEN. The thermo-hydraulic circuit comprises heater, heat exchanger, expansion tank, the pressure relief valve and pipes to interconnect the components. A glass tube is installed at the midpoint of the riser connected to the heater outlet. The natural circulation circuit is complemented by acquisition system of values of temperatures, flow and graphic interface. The instrumentation has thermocouples, volumetric flow meter, rotameter and high-speed digital camera. The experimental study is performed through analysis of information from measurements of temperatures at strategic points along the hydraulic circuit, besides natural circulation flow rates. The comparisons between analytical and experimental values are validated by viewing, recording and processing of the images for the flows patterns. Variables involved in the process of identification of flow regimes, dimensionless parameters, the phase velocity of the flow, initial boiling point, the phenomenon of 'flashing' pre-slug flow type were obtained experimentally. (author)

  9. Testing of a shrouded, short mixing stack gas eductor model using high temperature primary flow.

    OpenAIRE

    Eick, Ira James.

    1982-01-01

    Approved for public release; distribution is unlimited An existing apparatus for testing models of gas eductor systems using high temperature primary flow was redesigned and modified to provide improved control and performance over a wide range of gas temperatures and flow rates. Pumping coefficient, temperature, and pressure data were recorded for two gas eductor system models. The first, previously tested under hot flow conditions, consisted of a primary plate with four straight nozzle...

  10. High temperature flow behaviour of SiC reinforced lithium ...

    Indian Academy of Sciences (India)

    The flow behaviour of LAS glass changed from Newtonian to non-Newtonian due to the presence of crystalline phase. Further, with the addition of 40 vol.% SiC additions, the strain rate sensitivity of flow stress decreased. While the activation energy for flow in LAS was 300 kJ/mole, it increased to 995 kJ/mole with the ...

  11. Photocathodes for High Repetition Rate Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi, Ilan [Stony Brook Univ., NY (United States). Dept. of Physics and Astronomy. Center for Accelerator Science and Education

    2014-04-20

    This proposal brought together teams at Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL) and Stony Brook University (SBU) to study photocathodes for high repetition rate light sources such as Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). Below details the Principal Investigators and contact information. Each PI submits separately for a budget through his corresponding institute. The work done under this grant comprises a comprehensive program on critical aspects of the production of the electron beams needed for future user facilities. Our program pioneered in situ and in operando diagnostics for alkali antimonide growth. The focus is on development of photocathodes for high repetition rate Free Electron Lasers (FELs) and Energy Recovery Linacs (ERLs), including testing SRF photoguns, both normal-­conducting and superconducting. Teams from BNL, LBNL and Stony Brook University (SBU) led this research, and coordinated their work over a range of topics. The work leveraged a robust infrastructure of existing facilities and the support was used for carrying out the research at these facilities. The program concentrated in three areas: a) Physics and chemistry of alkali-­antimonide cathodes (BNL – LBNL) b) Development and testing of a diamond amplifier for photocathodes (SBU -­ BNL) c) Tests of both cathodes in superconducting RF photoguns (SBU) and copper RF photoguns (LBNL) Our work made extensive use of synchrotron radiation materials science techniques, such as powder-­ and single-­crystal diffraction, x-­ray fluorescence, EXAFS and variable energy XPS. BNL and LBNL have many complementary facilities at the two light sources associated with these laboratories (NSLS and ALS, respectively); use of these will be a major thrust of our program and bring our understanding of these complex materials to a new level. In addition, CHESS at Cornell will be used to continue seamlessly throughout the NSLS dark period and

  12. Cold flow mixing rate data for pulverized coal reactors

    Energy Technology Data Exchange (ETDEWEB)

    Memmott, V.J.; Smoot, L.D.

    1978-05-01

    To elucidate the mixing characteristics of particle-laden, confined jets in entrained-bed coal gasifiers, Brigham Young University examined the effects of velocity, density, injection angle, particle loading level, and particle size on the rate of particle and gas mixing. Researchers measured the gas velocity, particle mass flux, and gas composition at various radial and axial locations downstream of the primary jet exit plane. Increases in injection angle and secondary velocity significantly raised gas and particle mixing rates, while the effects of other variables were much less significant. Dispersion of particles lagged that of the gas in all cases investigated. Controlling the mixing processes may lead to increases in combustion efficiency or to a reduction in the rate of pollutant formation.

  13. Characteristics of the saliva flow rates of minor salivary glands in healthy people.

    Science.gov (United States)

    Wang, Zhen; Shen, Ming-Ming; Liu, Xiao-Jing; Si, Yan; Yu, Guang-Yan

    2015-03-01

    To investigate the normal range and characteristics of saliva secretion in the minor salivary glands (MSGs). The flow rates of MSGs were measured in 4 anatomical locations of oral mucosa, and the relationship between MSG flow rates and whole saliva flow rates were assessed in 300 healthy subjects stratified by age and sex. An additional 30 young females were further evaluated for flow symmetry, effects of stimulation, circadian effects in MSGs, and the relationship with the flow rates of major salivary glands. (1) The mean saliva flow rates were 2.10 ± 0.66 (lower labial glands), 2.14 ± 0.62 (upper labial glands), 2.88 ± 0.72 (buccal glands) and 2.15 ± 0.51 (palatal glands) μl/min/cm(2), respectively. The flow rate of buccal glands was significantly higher than the rates of SMGs in other locations (P 0.05), right vs. left (P > 0.05), and citric acid (2.5%) stimulation (P > 0.05). (4) Only labial MSG displayed a significant secretory circadian rhythm with the highest rate in the evening (P glands and that of unstimulated whole saliva (r = 0.195, P = 0.007). Our findings provide a reference for functional evaluation of MSGs and for donor site selection of MSG transplantation for treatment of severe dry eye syndrome. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. The effect of temperature fluctuations of reaction rate constants in turbulent reacting flows

    Science.gov (United States)

    Chinitz, W.; Antaki, P. J.; Kassar, G. M.

    1981-01-01

    Current models of turbulent reacting flows frequently use Arrhenius reaction rate constants obtained from static or laminar flow theory and/or experiments, or from best fits of static, laminar, and turbulent data. By treating the reaction rate constant as a continuous random variable which is temperature-dependent, the present study assesses the effect of turbulent temperature fluctuations on the reaction rate constant. This model requires that a probability density function (PDF) describing the nature of the fluctuations be specified. Three PDFs are examined: the clipped Gaussian, the beta PDF, and the ramp model. All the models indicate that the reaction rate constant is greater in a turbulent flow field than in an equivalent laminar flow. In addition, an amplification ratio, which is the ratio of the turbulent rate constant to the laminar rate constant, is defined and its behavior as a function of the mean temperature fluctuations is described

  15. A generalized Forchheimer radial flow model for constant-rate tests

    Science.gov (United States)

    Liu, Ming-Ming; Chen, Yi-Feng; Zhan, Hongbin; Hu, Ran; Zhou, Chuang-Bing

    2017-09-01

    Models used for data interpretation of constant-rate tests (CRTs) are commonly derived with the assumption of Darcian flow in an idealized integer flow dimension, where the non-Darcian nature of fluid flow and the complexity of flow geometry are disregarded. In this study, a Forchheimer's law-based analytical model is proposed with the assumption of buildup (or drawdown) decomposition for characterizing the non-Darcian flow in a generalized radial formation where the flow dimension n may become non-integer. The proposed model immediately reduces to Barker's (1988) model for Darcian flow in the generalized radial formation and to Mathias et al.'s (2008) model for non-Darcian flow in a two-dimensional confined aquifer. A comparison with numerical simulations shows that the proposed model behaves well at late times for flow dimension n > 1.5. The proposed model is finally applied for data interpretation of the constant-rate pumping tests performed at Ploemeur (Le Borgne et al., 2004), showing that the intrinsic hydraulic conductivity of formations will be underestimated and the specific storage will be overestimated if the non-Darcian effect is ignored. The proposed model is an extension of the generalized radial flow (GRF) model based on Forchheimer's law, which would be of significance for data interpretation of CRTs in aquifers of complex flow geometry in which non-Darcian flow occurs.

  16. Advances in high-rate uncooled detector fabrication at Raytheon

    Science.gov (United States)

    Black, S. H.; Kraft, R.; Medrano, A.; Kocian, T.; Bradstreet, D.; Williams, R.; Yang, T.

    2010-04-01

    Over the past two years Raytheon has made a major investment aimed at establishing a high volume uncooled manufacturing capability. This effort has addressed three elements of the uncooled value stream, namely bolometer fabrication, packaging and calibration/test. To facilitate a low cost / high volume source of bolometers Raytheon has formed a partnership with a high volume 200mm commercial silicon wafer fabrication. Over a 12 month period Raytheon has installed 200mm VOx deposition equipment, matched the metrology used on the Raytheon 150mm line, transferred the process flow used to fabricate Raytheon's double layer bolometer process and qualified the product. In this paper we will review the process transfer methodology and bolometer performance. To reduce bolometer packaging cost and increase production rates, Raytheon has implemented an automated packaging line. This line utilizes automated adhesive dispense, component pick and place, wire bonding and solder seal. In this paper we will review the process flow, qualification process and line capacity Calibration and test has traditionally been performed using a number of temperature chambers, with increased throughput being obtained by adding more chambers. This comes at the expense of increased test labor required to feed the chambers and an increased energy and floor space foot print. To avoid these collateral costs, Raytheon has implemented an automated robotic calibration cell capable of performing in excess of 5,000 calibrations a month. In this paper we will provide an overview of the calibration cell along with takt time and throughput data.

  17. A readout unit for high rate applications

    CERN Document Server

    Toledo, J; Domínguez, D; Guirao-Elias, A; Müller, H

    2002-01-01

    The LHCb readout unit (RU) is a custom entry stage to the readout network of a data-acquisition or trigger system. It performs subevent building from multiple link inputs toward a readout network via a PCI network interface or alternatively toward a high-speed link, via an S-link interface. Incoming event fragments are derandomized, buffered and assembled into single subevents. This process is based on a low- overhead framing convention and matching of equal event numbers. Programmable logic is used both in the input and output stages of the RU module, which may be configured either as a data-link multiplexer or as entry stage to a readout or trigger network. All FPGAs are interconnected via the PCI bus, which is hosted by a networked microprocessor card. Its main tasks are remote FPGA configuration and initialization of the PCI cards. The RU hardware architecture has been optimized for a throughput of up to 200 MB/s at a 1 MHz trigger rate, as required by the most demanding application, the LHCb level-1 trig...

  18. Local and Nonlocal Strain Rate Fields and Vorticity Alignment in Turbulent Flows

    OpenAIRE

    Hamlington, Peter E.; Schumacher, Jörg; Dahm, Werner J. A.

    2008-01-01

    Local and nonlocal contributions to the total strain rate tensor at any point in a flow are formulated from an expansion of the vorticity field in a local spherical neighborhood of radius R centered on x. The resulting exact expression allows the nonlocal (background) strain rate tensor to be obtained from the total strain rate tensor. In turbulent flows, where the vorticity naturally concentrates into relatively compact structures, this allows the local alignment of vorticity with the most e...

  19. In vitro simulation of in vivo pharmacokinetic model with intravenous administration via flow rate modulation.

    Science.gov (United States)

    Chen, Yuan-Cheng; Liang, Wang; Hu, Jia-Li; He, Gao-Li; Wu, Xiao-Jie; Liu, Xiao-Fang; Zhang, Jing; Hu, Xue-Qian

    2015-02-01

    The aim of this paper was to propose a method of flow rate modulation for simulation of in vivo pharmacokinetic (PK) model with intravenous injection based on a basic in vitro PK model. According to the rule of same relative change rate of concentration per unit time in vivo and in vitro, the equations for flow rate modulation were derived using equation method. Four examples from literature were given to show the application of flow rate modulation in the simulation of PK model of antimicrobial agents in vitro. Then an experiment was performed to confirm the feasibility of flow rate modulation method using levo-ornidazole as an example. The accuracy and precision of PK simulations were evaluated using average relative deviation (ARD), mean error and root mean squared error. In vitro model with constant flow rate could mimic one-compartment model, while the in vitro model with decreasing flow rate could simulate the linear mammillary model with multiple compartments. Zero-order model could be simulated using the in vitro model with elevating flow rate. In vitro PK model with gradually decreasing flow rate reproduced the two-compartment kinetics of levo-ornidazole quite well. The ARD was 0.925 % between in vitro PK parameters and in vivo values. Results suggest that various types of PK model could be simulated using flow rate modulation method without modifying the structure. The method provides uniform settings for the simulation of linear mammillary model and zero-order model based on in vitro one-compartment model, and brings convenience to the pharmacodynamic study.

  20. Effects on fuel spray characteristics and vaporization on energy release rates and flow field structure in a dump combustor

    Science.gov (United States)

    Bowman, C. T.; Hanson, R. K.; Vandsburger, U.; Allen, M. G.; McManus, K. R.

    1986-10-01

    An experimental investigation of the effects of fuel spray characteristics, specifically droplet size and extent of prevaporization, on energy release rate and flow field structure in a liquid-fueled dump combustor is in progress. Visualization and measurment of the spray characteristics and of the reacting flow field are carried out using high-speed schlieren photography and planar imaging techniques. An important element of the research is development of these imaging techniques for two-phase reacting flows. Progress to date is described in the development of several imaging techniques and initial results from experiments in the dump combustor.

  1. Passive sampling of perfluorinated chemicals in water: flow rate effects on chemical uptake.

    Science.gov (United States)

    Kaserzon, Sarit L; Vermeirssen, Etiënne L M; Hawker, Darryl W; Kennedy, Karen; Bentley, Christie; Thompson, Jack; Booij, Kees; Mueller, Jochen F

    2013-06-01

    A recently developed modified polar organic chemical integrative sampler (POCIS) provides a means for monitoring perfluorinated chemicals (PFCs) in water. However, changes in external flow rates may alter POCIS sampling behaviour and consequently affect estimated water concentrations of analytes. In this work, uptake kinetics of selected PFCs, over 15 days, were investigated. A flow-through channel system was employed with spiked river water at flow rates between 0.02 and 0.34 m s(-1). PFC sampling rates (Rs) (0.09-0.29 L d(-1) depending on analyte and flow rate) increased from the lowest to highest flow rate employed for some PFCs (MW ≤ 464) but not for others (MW ≥ 500). Rs's for some of these smaller PFCs were increasingly less sensitive to flow rate as this increased within the range investigated. This device shows promise as a sampling tool to support monitoring efforts for PFCs in a range of flow rate conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Target heart rate to determine the normal value of coronary flow reserve during dobutamine stress echocardiography

    Directory of Open Access Journals (Sweden)

    Rousse Maria G

    2011-04-01

    Full Text Available Abstract Background The determination of coronary flow reserve (CFR is an essential concept at the moment of decision-making in ischemic heart disease. There are several direct and indirect tests to evaluate this parameter. In this sense, dobutamine stress echocardiography is one of the pharmacological method most commonly used worldwide. It has been previously demonstrated that CFR can be determined by this technique. Despite our wide experience with dobutamine stress echocardiography, we ignored the necessary heart rate to consider sufficient the test for the analysis of CFR. For this reason, our main goal was to determine the velocity of coronary flow in each stage of dobutamine stress echocardiography and the heart rate value necessary to double the baseline values of coronary flow velocity in the territory of the left anterior descending (LAD coronary artery. Methods A total of 33 consecutive patients were analyzed. The patients included had low risk for coronary artery disease. All the participants underwent dobutamine stress echocardiography and coronary artery flow velocity was evaluated in the distal segment of LAD coronary artery using transthoracic color-Doppler echocardiography. Results The feasibility of determining CFR in the territory of the LAD during dobutamine stress echocardiography was high: 31/33 patients (94%. Mean CFR was 2.67 at de end of dobutamine test. There was an excellent concordance between delta HR (difference between baseline HR and maximum HR and the increase in the CFR (correlation coefficient 0.84. In this sense, we found that when HR increased by 50 beats, CFR was ≥ 2 (CI 93-99.2%. In addition, 96.4% of patients reached a CFR ≥ 2 (IC 91.1 - 99% at 75% of their predicted maximum heart rate. Conclusions We found that the feasibility of dobutamine stress echocardiography to determine CFR in the territory of the LAD coronary artery was high. In this study, it was necessary to achieve a difference of 50 bpm

  3. High voltage high repetition rate pulse using Marx topology

    Science.gov (United States)

    Hakki, A.; Kashapov, N.

    2015-06-01

    The paper describes Marx topology using MOSFET transistors. Marx circuit with 10 stages has been done, to obtain pulses about 5.5KV amplitude, and the width of the pulses was about 30μsec with a high repetition rate (PPS > 100), Vdc = 535VDC is the input voltage for supplying the Marx circuit. Two Ferrite ring core transformers were used to control the MOSFET transistors of the Marx circuit (the first transformer to control the charging MOSFET transistors, the second transformer to control the discharging MOSFET transistors).

  4. Feasibility of exhaled nitric oxide measurements at various flow rates in children with asthma.

    Science.gov (United States)

    Robroeks, Charlotte M H H T; van Vliet, Dillys; Hendriks, Han J E; Dompeling, Edward; Jöbsis, Quirijn

    2010-02-01

    Measurement of bronchial and alveolar exhaled nitric oxide (NO) levels could be of clinical importance for the treatment of asthma. To discriminate between alveolar and bronchial NO, measurements need to be assessed at various flow rates. To study the feasibility, linearity, and long-term repeatability of NO measurements at four different exhalation flow rates in children with asthma. Twenty-one children with moderate persistent asthma, aged 6-12 yrs, were included in the study. NO was measured according to the ATS/ERS guidelines, using the NIOX analyzer with flow restrictors of 30, 50, 100, and 200 ml/s. Duration of the measurements ranged from 6-10 s, depending on the flow rate. The tests were repeated 3 and 6 months after the first NO measurement. Feasibility of NO measurements at these four flow rates increased from 67% to 91% and 95% at the first, second and third visit, respectively. A significant learning effect was present. Age and lung function indices did not influence success or failure of the tests. At the first measurements occasions, no problems occurred during the NO analysis at a 100 ml/s flow rate. There was a 75-90% success rate when performing the test using flow rates of 30, 50, and 200 ml/s. However, repeating the tests resulted in a 100% success rate. Measurements were not successful if: (i) children ran out of air; (ii) NO concentration exceeded 200 ppb; (iii) the measured NO flow was unstable; and (iv) the NO plateau was not formed. This study showed good feasibility and linearity of NO measurements in asthmatic children of 6 yrs and over at flow rates between 50-200 ml/s. A significant learning effect was present. The long-term reproducibility of alveolar and bronchial NO values during 6 months was moderate. © 2010 The Authors. Journal compilation © 2010 Blackwell Munksgaard.

  5. Phosphorus mobilization in rewetted peat and sand at variable flow rate and redox regimes

    DEFF Research Database (Denmark)

    Kjærgaard, Charlotte; Heiberg, Lisa; Jensen, Henning S.

    2012-01-01

    rates from 7.6 to 11 mg P m−2 day−1. Organic or particulate P contributed to 40–45% of total P losses from the peat. In contrast, the high O2 supply during high flow rate kept the peat oxic and lowered TP release rates to 6.7 mg P m−2 day−1. The carbon poor sand demonstrated that this soil type......Despite the high priority of wetland restoration as the primary measure to reduce agricultural nutrient loads, it is also widely recognized that wetlands restored on former agricultural land could potentially release accumulated phosphorus (P) and become a source of eutrophication. Simulating...... regimes in the two soils during 21 or 67 days of continuous percolation at either 1 or 4 mm h−1. Anoxic conditions occurred in the peat soil at both low oxygen supply and anoxic infiltration, causing reductive Fe(III) dissolution with high Fe(II) and P effluent concentrations and total P (TP) release...

  6. High strain rate behavior of alloy 800H at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Shafiei, E., E-mail: shafiei.ehsan.mse@gmail.com

    2016-05-15

    In this paper, a new model using linear estimation of strain hardening rate vs. stress, has been developed to predict dynamic behavior of alloy 800H at high temperatures. In order to prove the accuracy and competency of the presented model, Johnson–Cook model pertaining modeling of flow stress curves was used. Evaluation of mean error of flow stress at deformation temperatures from 850 °C to 1050 °C and at strain rates of 5 S{sup −1} to 20 S{sup −1} indicates that the predicted results are in a good agreement with experimentally measured ones. This analysis has been done for the stress–strain curves under hot working condition for alloy 800H. However, this model is not dependent on the type of material and can be extended for any similar conditions.

  7. High mitogenomic evolutionary rates and time dependency.

    NARCIS (Netherlands)

    Subramanian, S.; Denver, D.R.; Millar, C.D.; Heupink, T.; Aschrafi, A.; Emslie, S.D.; Baroni, C.; Lambert, D.M.

    2009-01-01

    Using entire modern and ancient mitochondrial genomes of Adelie penguins (Pygoscelis adeliae) that are up to 44000 years old, we show that the rates of evolution of the mitochondrial genome are two to six times greater than those estimated from phylogenetic comparisons. Although the rate of

  8. Effect of different river flow rates on biomarker responses in common carp (Cyprinus carpio).

    Science.gov (United States)

    Hackenberger, Branimir K; Velki, Mirna; Lončarić, Zeljka; Hackenberger, Davorka K; Ečimović, Sandra

    2015-02-01

    The present study investigated effects of different river flow rates on basal activities of selected biomarkers and the occurrence of oxidative stress in the common carp (Cyprinus carpio). Juvenile carp were exposed to different river flow rates (5-120 cm/s) by caging for 3 weeks. After this period, one half of the fish were sacrificed and used for analysis. The other half received a single intraperitoneal injection of 3-methylcholanthrene (3-MC) and after 6 days were sacrificed and used for analysis. In order to investigate whether the physical activity of carp in the environment will influence the condition status of carp, following biomarkers were measured - activities of glutathione S-transferase (GST), catalase (CAT) and ethoxyresorufin-O-deethylase (EROD) and concentration of protein carbonyls (PC). The results showed that different flow rates significantly influenced biochemical biomarkers. The basal activity of GST did not change significantly after exposure to different river flow rates, whereas the activity of CAT increased with increasing river flow rates. The application of 3-MC caused significant increases in GST and CAT activities, but there were no difference between 3-MC control and 3-MC different flow rates. The occurrence of oxidative stress as a result of exposure to increased physical activity, i.e. increased river flow rates, was confirmed by measurement of PC levels - the level of PC increased with increasing river flow rates. Measurement of EROD basal activity showed that at lower river flow rates the EROD activity increased and at higher river flow rates decreased towards control levels demonstrating a close relationship between oxidative stress, PC levels and EROD activity. Obviously, biomarker responses in carp of different condition status can differ substantially. It can be concluded that flow rate may be an important factor in biomonitoring of rivers using biomarkers and since at different locations river water flow rate can vary

  9. Analysis of Winter Low-Flow Rates in New Hampshire Streams

    Science.gov (United States)

    1990-08-01

    AD-A229 512 TI1P FILE COPY * Analysis of Winter Low- Flow Rates in New Hampshire Streams Rae Ann Melloh August 1990 a DTIC fpIm ELECTE iN O V21WOl D i...Winter Low- Flow Rates in New Hampshire Streams Rae Ann Melloh August 1990 Prepared for OFFICE OF THE CHIEF OF ENGINEERS Approved for public release...Analysis of Winter Low- Flow Rates in New Hampshire Streams RAE ANN MELLOH INTRODUCTION watercourse from the drainage area divide and water- course storage

  10. Maximizing protein translation rate in the non-homogeneous ribosome flow model: a convex optimization approach.

    Science.gov (United States)

    Poker, Gilad; Zarai, Yoram; Margaliot, Michael; Tuller, Tamir

    2014-11-06

    Translation is an important stage in gene expression. During this stage, macro-molecules called ribosomes travel along the mRNA strand linking amino acids together in a specific order to create a functioning protein. An important question, related to many biomedical disciplines, is how to maximize protein production. Indeed, translation is known to be one of the most energy-consuming processes in the cell, and it is natural to assume that evolution shaped this process so that it maximizes the protein production rate. If this is indeed so then one can estimate various parameters of the translation machinery by solving an appropriate mathematical optimization problem. The same problem also arises in the context of synthetic biology, namely, re-engineer heterologous genes in order to maximize their translation rate in a host organism. We consider the problem of maximizing the protein production rate using a computational model for translation-elongation called the ribosome flow model (RFM). This model describes the flow of the ribosomes along an mRNA chain of length n using a set of n first-order nonlinear ordinary differential equations. It also includes n + 1 positive parameters: the ribosomal initiation rate into the mRNA chain, and n elongation rates along the chain sites. We show that the steady-state translation rate in the RFM is a strictly concave function of its parameters. This means that the problem of maximizing the translation rate under a suitable constraint always admits a unique solution, and that this solution can be determined using highly efficient algorithms for solving convex optimization problems even for large values of n. Furthermore, our analysis shows that the optimal translation rate can be computed based only on the optimal initiation rate and the elongation rate of the codons near the beginning of the ORF. We discuss some applications of the theoretical results to synthetic biology, molecular evolution, and functional genomics. © 2014 The

  11. Tangential stretching rate (TSR) analysis of non premixed reactive flows

    KAUST Repository

    Valorani, Mauro

    2016-10-16

    We discuss how the Tangential stretching rate (TSR) analysis, originally developed and tested for spatially homogeneous systems (batch reactors), is extended to spatially non homogeneous systems. To illustrate the effectiveness of the TSR diagnostics, we study the ignition transient in a non premixed, reaction–diffusion model in the mixture fraction space, whose dependent variables are temperature and mixture composition. The reactive mixture considered is syngas/air. A detailed H2/CO mechanism with 12 species and 33 chemical reactions is employed. We will discuss two cases, one involving only kinetics as a model of front propagation purely driven by spontaneous ignition, the other as a model of deflagration wave involving kinetics/diffusion coupling. We explore different aspects of the system dynamics such as the relative role of diffusion and kinetics, the evolution of kinetic eigenvalues, and of the tangential stretching rates computed by accounting for the combined action of diffusion and kinetics as well for kinetics only. We propose criteria based on the TSR concept which allow to identify the most ignitable conditions and to discriminate between spontaneous ignition and deflagration front.

  12. Measurement and Modelling of Air Flow Rate in a Naturally Ventilated Double Skin Facade

    DEFF Research Database (Denmark)

    Heiselberg, Per; Kalyanova, Olena; Jensen, Rasmus Lund

    2008-01-01

    Air flow rate in a naturally ventilated double skin façade (DSF) is extremely difficult to measure due to the stochastic nature of wind, and as a consequence non-uniform and dynamic flow conditions. This paper describes the results of two different methods to measure the air flow in a full......-scale outdoor test facility with a naturally ventilated double skin façade. Although both methods are difficult to use under such dynamic air flow conditions, they show reasonable agreement and can be used for experimental validation of numerical models of natural ventilation air flow in DSF. Simulations...... by the thermal simulation program, BSim, based on measured weather boundary conditions are compared to the measured air temperature, temperature gradient and mass flow rate in the DSF cavity. The results show that it is possible to predict the temperature distribution and airflow in the DSF although some...

  13. Does water content or flow rate control colloid transport in unsaturated porous media?

    Science.gov (United States)

    Knappenberger, Thorsten; Flury, Markus; Mattson, Earl D; Harsh, James B

    2014-04-01

    Mobile colloids can play an important role in contaminant transport in soils: many contaminants exist in colloidal form, and colloids can facilitate transport of otherwise immobile contaminants. In unsaturated soils, colloid transport is, among other factors, affected by water content and flow rate. Our objective was to determine whether water content or flow rate is more important for colloid transport. We passed negatively charged polystyrene colloids (220 nm diameter) through unsaturated sand-filled columns under steady-state flow at different water contents (effective water saturations Se ranging from 0.1 to 1.0, with Se = (θ - θr)/(θs - θr)) and flow rates (pore water velocities v of 5 and 10 cm/min). Water content was the dominant factor in our experiments. Colloid transport decreased with decreasing water content, and below a critical water content (Se colloid transport was inhibited, and colloids were strained in water films. Pendular ring and water film thickness calculations indicated that colloids can move only when pendular rings are interconnected. The flow rate affected retention of colloids in the secondary energy minimum, with less colloids being trapped when the flow rate increased. These results confirm the importance of both water content and flow rate for colloid transport in unsaturated porous media and highlight the dominant role of water content.

  14. Implications of sediment transport by subglacial water flow for interpreting contemporary glacial erosion rates

    Science.gov (United States)

    Beaud, Flavien; Flowers, Gwenn E.; Venditti, Jeremy G.

    2017-04-01

    The role of glaciers in landscape evolution is central to the interactions between climate and tectonic forces at high latitudes and in mountainous regions. Sediment yields from glacierized basins are used to quantify contemporary erosion rates on seasonal to decadal timescales, often under the assumption that subglacial water flow is the main contributor to these yields. Two recent studies have furthermore used such sediment fluxes to calibrate a glacial erosion rule, where erosion rate scales with ice sliding speed raised to a power greater than one. Subglacial sediment transport by water flow has however seldom been studied, thus the controls on sediment yield from glacierized basins remain enigmatic. To bridge this gap, we develop a 1-D model of morphodynamics in semi-circular bedrock-floored subglacial channels. We adapt a sediment conservation law from the fluvial literature, developed for both mixed bedrock / alluvial and alluvial conditions, to subglacial channels. Channel evolution is a function of the traditional melt-opening due to viscous heat dissipation from the water flow, and creep closure of the overlying ice, to which we add the closure or enlargement due to sediment deposition or removal, respectively. Using a simple ice geometry representing a land-terminating glacier, we find that the shear stresses produced by the water flow on the bed decrease significantly near the terminus. As the ice thins, creep closure decreases and large hydraulic potential gradients cannot be sustained. The resulting gradients in sediment transport lead to a bottleneck, and sediment accumulates if the sediment supply is adequate. A similar bottleneck occurs if a channel is well established and water discharge drops. Whether such constriction happens in space of time, in the presence of a sufficiently large sediment supply sediment accumulates temporarily near the terminus, followed shortly thereafter by enhanced sediment transport. Reduction in the cross-sectional area

  15. Indicators of Student Flow Rates in Honduras: An Assessment of an Alternative Methodology, with Two Methodologies for Estimating Student Flow Rates. BRIDGES Research Report No. 6.

    Science.gov (United States)

    Cuadra, Ernesto; Crouch, Luis

    Student promotion, repetition, and dropout rates constitute the basic data needed to forecast future enrollment and new resources. Information on student flow is significantly related to policy formulation aimed at improving internal efficiency, because dropping out and grade repetition increase per pupil cost, block access to eligible school-age…

  16. Effects of neuropeptide Y on regulation of blood flow rate in canine myocardium

    DEFF Research Database (Denmark)

    Svendsen, Jesper Hastrup; Sheikh, S P; Jørgensen, J

    1990-01-01

    The effect of neuropeptide Y (NPY) on tension development was examined in isolated canine coronary arteries, and the effects on local myocardial blood flow rate were studied in open-chest anesthetized dogs by the local 133Xe washout technique. By immunohistochemistry, numerous NPY......+. In contrast, intracoronary NPY (0.01-10 micrograms) induced a considerable degree of vasoconstriction; the reduction of blood flow rate was dose related, with a maximum reduction to 52% of control values. The effect of intracoronary NPY (1 microgram) on maximally relaxed arterioles elicited by 30 s...... of ischemia was studied in separate experiments during reactive hyperemia. NPY induced a decrease in maximum blood flow during reactive hyperemia (166.6 vs. 214.6% of preocclusive blood flow rate, mean values; P = 0.05), an increase in the cumulative excess blood flow (61.0 vs. 35.3 ml/100 g; P = 0...

  17. Power flow controller with a fractionally rated back-to-back converter

    Science.gov (United States)

    Divan, Deepakraj M.; Kandula, Rajendra Prasad; Prasai, Anish

    2016-03-08

    A power flow controller with a fractionally rated back-to-back (BTB) converter is provided. The power flow controller provide dynamic control of both active and reactive power of a power system. The power flow controller inserts a voltage with controllable magnitude and phase between two AC sources at the same frequency; thereby effecting control of active and reactive power flows between the two AC sources. A transformer may be augmented with a fractionally rated bi-directional Back to Back (BTB) converter. The fractionally rated BTB converter comprises a transformer side converter (TSC), a direct-current (DC) link, and a line side converter (LSC). By controlling the switches of the BTB converter, the effective phase angle between the two AC source voltages may be regulated, and the amplitude of the voltage inserted by the power flow controller may be adjusted with respect to the AC source voltages.

  18. D0 Silicon Upgrade: Calculating Mass Flow Rates at Sub-Sonic Conditions Trhough Venturis (FT-4052-H & FT-4053-H) and an Orifice Plate (F)-2019-H)

    Energy Technology Data Exchange (ETDEWEB)

    Zaczek, Mauiusz; /Fermilab

    1996-08-15

    The purpose of this engineering note is to explain the method involved in calculating the mass flow rates through venturis and orifice plates at sub-sonic conditions. In particular, the mass flow rate calculations are required for two FLOW-DYNE venturi flow meters, serial no. 35821 and no. 35822, and an orifice plate flow meter, serial no. 35823. The two venturis, FT-4052-H and FT-4053-H, are located in the D-Zero VLPC valve box at the refrigerator and the orifice plate, FO-2019-H, is on the high pressure helium supply line in the assembly building.

  19. Inspiratory flow rates during hard work when breathing through different respirator inhalation and exhalation resistances.

    Science.gov (United States)

    Coyne, Karen; Caretti, David; Scott, William; Johnson, Arthur; Koh, Frank

    2006-09-01

    There has been a long-standing debate regarding the adequacy of airflow rates used in respirator certification testing and whether these test flow rates underestimate actual values. This study investigated breath by breath inspiratory peak flow rate, minute ventilation, and instantaneous flow rates of eight young, healthy volunteers walking on a treadmill at 80-85% of maximal aerobic capacity until exhaustion while wearing an air-purifying respirator with one of eight combinations of inhalation and exhalation resistance. An analysis of variance was performed to identify differences among the eight conditions. Scheffe's post hoc analysis indicated which means differed. The group of conditions with the highest average value for each parameter was identified and considered to represent a worst-case scenario. Data was reported for these conditions. A Gaussian distribution was fit to the data and the 99.9% probability levels determined. The 99.9% probability level for the peak and instantaneous flow rates were 374 L/min and 336 L/min, respectively. The minute ventilation distribution was not Gaussian. Less than 1% of the recorded minute ventilations exceeded 135 L/min. Instantaneous flow rates exceeded the National Institute for Occupational Safety and Health's respirator test standards of 64, 85, and 100 L/min constant flow 91%, 87%, and 82% of the time, respectively. The recorded minute ventilations exceeded the 40 L/min minute ventilation test standard (for tests with a sinusoidal flow pattern) 100% of the time. This study showed that young, healthy respirator wearers generated peak flow rates, minute ventilations, and instantaneous flow rates that consistently exceeded current test standards. Their flow rates should be higher than those of a respirator wearer performing occupational work and could be considered upper limits. Testing respirators and respirator cartridges using a sinusoidal breathing pattern with a minute ventilation of 135 L/min (peak flow rate

  20. The use of high-flow nasal cannula in the pediatric emergency department.

    Science.gov (United States)

    Slain, Katherine N; Shein, Steven L; Rotta, Alexandre T

    To summarize the current literature describing high-flow nasal cannula use in children, the components and mechanisms of action of a high-flow nasal cannula system, the appropriate clinical applications, and its role in the pediatric emergency department. A computer-based search of PubMed/MEDLINE and Google Scholar for literature on high-flow nasal cannula use in children was performed. High-flow nasal cannula, a non-invasive respiratory support modality, provides heated and fully humidified gas mixtures to patients via a nasal cannula interface. High-flow nasal cannula likely supports respiration though reduced inspiratory resistance, washout of the nasopharyngeal dead space, reduced metabolic work related to gas conditioning, improved airway conductance and mucociliary clearance, and provision of low levels of positive airway pressure. Most data describing high-flow nasal cannula use in children focuses on those with bronchiolitis, although high-flow nasal cannula has been used in children with other respiratory diseases. Introduction of high-flow nasal cannula into clinical practice, including in the emergency department, has been associated with decreased rates of endotracheal intubation. Limited prospective interventional data suggest that high-flow nasal cannula may be similarly efficacious as continuous positive airway pressure and more efficacious than standard oxygen therapy for some patients. Patient characteristics, such as improved tachycardia and tachypnea, have been associated with a lack of progression to endotracheal intubation. Reported adverse effects are rare. High-flow nasal cannula should be considered for pediatric emergency department patients with respiratory distress not requiring immediate endotracheal intubation; prospective, pediatric emergency department-specific trials are needed to better determine responsive patient populations, ideal high-flow nasal cannula settings, and comparative efficacy vs. other respiratory support modalities

  1. Optimization of carbon dioxide supply in raceway reactors: Influence of carbon dioxide molar fraction and gas flow rate.

    Science.gov (United States)

    Duarte-Santos, T; Mendoza-Martín, J L; Acién Fernández, F G; Molina, E; Vieira-Costa, J A; Heaven, S

    2016-07-01

    Influence of CO2 composition and gas flow rate to control pH in a pilot-scale raceway producing Scenedesmus sp. was studied. Light and temperature determined the biomass productivity whereas neither the CO2 molar fraction nor the gas flow rate used influenced it; because pH was always controlled and carbon limitation did not take place. The CO2 molar fraction and the gas flow rate influenced carbon loss in the system. At low CO2 molar fraction (2-6%) or gas flow rate (75-100l·min(-1)) the carbon efficiency in the sump was higher than 95%, 85% of the injected carbon being transformed into biomass. Conversely, at high CO2 molar fraction (14%) or gas flow rate (150l·min(-1)) the carbon efficiency in the sump was lower than 67%, 32% of the carbon being fixed as biomass. Analysis here reported allows the pH control to be optimized and production costs to be reduced by optimizing CO2 efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Erythrocyte filtrability measurement by the initial flow rate method.

    Science.gov (United States)

    Hanss, M

    1983-01-01

    A new filtration technique, based on the initial filtration rate of a diluted RBC suspension through 5 mu Nucleopore filter is described. As only a few hundreds RBCs traverse each pore and as the measurement are made in a few seconds, the method is by large insensitive to filter plugging and to sedimentation effects. The results are given as a filtration index IF which is, as a first order approximation, independent of the filter conductance and of the suspending medium viscosity. The filtration times are measured electronically. The filters are re-used many times. The influence on the results reproducibility of RBC washing, of the anticoagulant, of the blood sample and the suspension storage times are considered. With our technical procedure, the relative incertitude on the measurement of I.F. is about +/- 10%. The filtration index is shown to be an intrinsic RBC filterability property.

  3. Ultrasonic 3-D Vector Flow Method for Quantitative In Vivo Peak Velocity and Flow Rate Estimation

    DEFF Research Database (Denmark)

    Holbek, Simon; Ewertsen, Caroline; Bouzari, Hamed

    2017-01-01

    Current clinical ultrasound (US) systems are limited to show blood flow movement in either 1-D or 2-D. In this paper, a method for estimating 3-D vector velocities in a plane using the transverse oscillation method, a 32×32 element matrix array, and the experimental US scanner SARUS is presented....

  4. Flow rate dependency of critical wall shear stress in a radial-flow cell

    DEFF Research Database (Denmark)

    Detry, J.G.; Jensen, Bo Boye Busk; Sindic, M.

    2009-01-01

    In the present work, a radial-flow cell was used to study the removal of starch particle aggregates from several solid substrates (glass, stainless steel, polystyrene and PTFE) in order to determine the critical wall shear stress value for each case. The particle aggregates were formed by aspersi...

  5. Performance of high-rate gravel-packed oil wells

    Energy Technology Data Exchange (ETDEWEB)

    Unneland, Trond

    2001-05-01

    Improved methods for the prediction, evaluation, and monitoring of performance in high-rate cased-hole gravel-packed oil wells are presented in this thesis. The ability to predict well performance prior to the gravel-pack operations, evaluate the results after the operation, and monitor well performance over time has been improved. This lifetime approach to performance analysis of gravel-packed oil wells contributes to increase oil production and field profitability. First, analytical models available for prediction of performance in gravel-packed oil wells are reviewed, with particular emphasis on high-velocity flow effects. From the analysis of field data from three North Sea oil fields, improved and calibrated cased-hole gravel-pack performance prediction models are presented. The recommended model is based on serial flow through formation sand and gravel in the perforation tunnels. In addition, new correlations for high-velocity flow in high-rate gravel-packed oil wells are introduced. Combined, this improves the performance prediction for gravel-packed oil wells, and specific areas can be targeted for optimized well design. Next, limitations in the current methods and alternative methods for evaluation and comparison of well performance are presented. The most widely used parameter, the skin factor, remains a convenient and important parameter. However, using the skin concept in direct comparisons between wells with different reservoir properties may result in misleading or even invalid conclusions. A discussion of the parameters affecting the skin value, with a clarification of limitations, is included. A methodology for evaluation and comparison of gravel-packed well performance is presented, and this includes the use of results from production logs and the use of effective perforation tunnel permeability as a parameter. This contributes to optimized operational procedures from well to well and from field to field. Finally, the data sources available for

  6. Highly simplified lateral flow-based nucleic acid sample preparation and passive fluid flow control

    Science.gov (United States)

    Cary, Robert E.

    2015-12-08

    Highly simplified lateral flow chromatographic nucleic acid sample preparation methods, devices, and integrated systems are provided for the efficient concentration of trace samples and the removal of nucleic acid amplification inhibitors. Methods for capturing and reducing inhibitors of nucleic acid amplification reactions, such as humic acid, using polyvinylpyrrolidone treated elements of the lateral flow device are also provided. Further provided are passive fluid control methods and systems for use in lateral flow assays.

  7. Synthesis of Core@Shell Nanostructures in a Continuous Flow Droplet Reactor: Controlling Structure through Relative Flow Rates.

    Science.gov (United States)

    Santana, Joshua S; Koczkur, Kallum M; Skrabalak, Sara E

    2017-06-20

    Bimetallic nanostructures are primarily synthesized in small volume batches. However, droplet-based reactors are receiving attention due to their ability to maintain thermal and compositional equilibrium within and between droplets, enabling flow operations for inline analyses and the scale-up of nanomaterial syntheses. Here, the syntheses of shape-controlled core@shell Au@Pd nanostructures with variable shell thicknesses are reported through control of the relative flow rates of reagents within the microreactor. Specifically, Pd shells were grown on cubic or octahedral Au seeds, selected as a model system. In batch reactions, shell thickness is determined by precursor concentration; however, as shown here, precursor feedstock concentration can be held constant, with the precursor concentration within the droplets being controlled through relative flow rates. This approach allows process conditions to be modified inline rather than from batch to batch to achieve particles with different shell thicknesses, and this procedure should be applicable to other multicomponent systems.

  8. Evaluation of the impact of viscosity, injection volume, and injection flow rate on subcutaneous injection tolerance

    Science.gov (United States)

    Berteau, Cecile; Filipe-Santos, Orchidée; Wang, Tao; Rojas, Humberto E; Granger, Corinne; Schwarzenbach, Florence

    2015-01-01

    Aim The primary objective of this study was to evaluate the impact of fluid injection viscosity in combination with different injection volumes and flow rates on subcutaneous (SC) injection pain tolerance. Methods The study was a single-center, comparative, randomized, crossover, Phase I study in 24 healthy adults. Each participant received six injections in the abdomen area of either a 2 or 3 mL placebo solution, with three different fluid viscosities (1, 8–10, and 15–20 cP) combined with two different injection flow rates (0.02 and 0.3 mL/s). All injections were performed with 50 mL syringes and 27G, 6 mm needles. Perceived injection pain was assessed using a 100 mm visual analog scale (VAS) (0 mm/no pain, 100 mm/extreme pain). The location and depth of the injected fluid was assessed through 2D ultrasound echography images. Results Viscosity levels had significant impact on perceived injection pain (P=0.0003). Specifically, less pain was associated with high viscosity (VAS =12.6 mm) than medium (VAS =16.6 mm) or low (VAS =22.1 mm) viscosities, with a significant difference between high and low viscosities (P=0.0002). Target injection volume of 2 or 3 mL was demonstrated to have no significant impact on perceived injection pain (P=0.89). Slow (0.02 mL/s) or fast (0.30 mL/s) injection rates also showed no significant impact on perceived pain during SC injection (P=0.79). In 92% of injections, the injected fluid was located exclusively in SC tissue whereas the remaining injected fluids were found located in SC and/or intradermal layers. Conclusion The results of this study suggest that solutions of up to 3 mL and up to 15–20 cP injected into the abdomen within 10 seconds are well tolerated without pain. High viscosity injections were shown to be the most tolerated, whereas injection volume and flow rates did not impact perceived pain. PMID:26635489

  9. Evaluation of the impact of viscosity, injection volume, and injection flow rate on subcutaneous injection tolerance

    Directory of Open Access Journals (Sweden)

    Berteau C

    2015-11-01

    Full Text Available Cecile Berteau,1 Orchidée Filipe-Santos,1 Tao Wang,2 Humberto E Rojas,2 Corinne Granger,1 Florence Schwarzenbach1 1Becton-Dickinson Medical Pharmaceutical Systems, Le Pont de Claix, France; 2Eli Lilly and Company, Indianapolis, IN, USA Aim: The primary objective of this study was to evaluate the impact of fluid injection viscosity in combination with different injection volumes and flow rates on subcutaneous (SC injection pain tolerance. Methods: The study was a single-center, comparative, randomized, crossover, Phase I study in 24 healthy adults. Each participant received six injections in the abdomen area of either a 2 or 3 mL placebo solution, with three different fluid viscosities (1, 8–10, and 15–20 cP combined with two different injection flow rates (0.02 and 0.3 mL/s. All injections were performed with 50 mL syringes and 27G, 6 mm needles. Perceived injection pain was assessed using a 100 mm visual analog scale (VAS (0 mm/no pain, 100 mm/extreme pain. The location and depth of the injected fluid was assessed through 2D ultrasound echography images. Results: Viscosity levels had significant impact on perceived injection pain (P=0.0003. Specifically, less pain was associated with high viscosity (VAS =12.6 mm than medium (VAS =16.6 mm or low (VAS =22.1 mm viscosities, with a significant difference between high and low viscosities (P=0.0002. Target injection volume of 2 or 3 mL was demonstrated to have no significant impact on perceived injection pain (P=0.89. Slow (0.02 mL/s or fast (0.30 mL/s injection rates also showed no significant impact on perceived pain during SC injection (P=0.79. In 92% of injections, the injected fluid was located exclusively in SC tissue whereas the remaining injected fluids were found located in SC and/or intradermal layers. Conclusion: The results of this study suggest that solutions of up to 3 mL and up to 15–20 cP injected into the abdomen within 10 seconds are well tolerated without pain. High

  10. Standard blood flow rates of cardiopulmonary bypass are adequate in awake on-pump cardiac surgery.

    Science.gov (United States)

    Porizka, Michal; Stritesky, Martin; Semrad, Michal; Dobias, Milos; Dohnalova, Alena; Korinek, Josef

    2011-04-01

    Standard blood flow rates for cardiopulmonary bypass have been assumed to be the same for awake cardiac surgery with thoracic epidural anesthesia (TEA) as for general anesthesia. However, compared with general anesthesia, awake cardiac surgery with epidural anesthesia may be associated with higher oxygen consumption and may result in lactic acidosis when standard blood flow rates were used. The aim of our study was to investigate if standard blood flow rates are adequate in awake cardiac surgery. Forty-five patients undergoing elective on-pump cardiac surgery were assigned to receive either epidural (Group TEA, n=15), combined (Group TEA-GA, n=15) or general (Group GA, n=15) anesthesia. To monitor the adequacy of standard blood flow rates, arterial lactate, acid base parameters, and central venous and jugular bulb saturation were measured at six time points (before, during, and after the surgery) in all groups. Blood flow rates were adjusted when needed. No lactic acidosis has developed in any group (p=NS). TEA as compared with TEA-GA and GA groups had lower central venous (67±4%, 75±11%, and 72±13%, respectively, pflow rates adjustments in any study group and no ventilatory support in TEA group were required. Under careful monitoring, the use of standard blood flow rates is adequate for patients undergoing awake on-pump normothermic cardiac surgery. Copyright © 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

  11. Customer Order Flow, Intermediaries, and Discovery of the Equilibrium Risk-Free Rate

    NARCIS (Netherlands)

    Menkveld, A.J.; Sarkar, A.; van der Wel, M.

    2012-01-01

    Macro announcements change the equilibrium risk-free rate. We find that Treasury prices reflect part of the impact instantaneously, but intermediaries rely on their customer order flow after the announcement to discover the full impact. This customer flow informativeness is strongest when analyst

  12. Characterisation of medical microfluidic systems regarding fast changing flow rates using optical front tracking methods.

    Science.gov (United States)

    Schroeter, Joerg; Del Bianco, Lino; Damiani, Christian; Klein, Stephan; Nestler, Bodo

    2017-10-01

    The presented optical flow metering methods are appropriate to characterise the dynamic properties of microfluidic systems. The dynamic behaviour of clinical or medical devices, micro pumps and flow sensors based on thermal methods were investigated. The Camera-System covers a flow range from 50nl/min to 500µl/min. The uncertainty is less than 4%, sample rates up to 5kS/s. The Displacement-Sensor-System covers a flow range between 100µl/min and 50ml/min. The uncertainty is less than 3% at sample rates up to 49kS/s. It was shown that measuring pulsating flow rates with thermal flow sensors is possible, but the signal is low pass filtered. The low pass behaviour is determined by the thermal properties, thermal resistance and heat capacity, of the flow channel. But the mean flow rate was always measured properly. The fluidic properties of two different types of micro pumps were examined and characterised exemplary. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  13. Passive sampling of perfluorinated chemicals in water: Flow rate effects on chemical uptake

    NARCIS (Netherlands)

    Kaserzon, S.L.; Vermeirssen, E.L.M.; Hawker, D.W.; Kennedy, K.; Bentley, C.; Thompson, J.; Booij, K.; Mueller, J.F.

    2013-01-01

    A recently developed modified polar organic chemical integrative sampler (POCIS) provides a means for monitoring perfluorinated chemicals (PFCs) in water. However, changes in external flow rates may alter POCIS sampling behaviour and consequently affect estimated water concentrations of analytes. In

  14. The relationship between sap-flow rate and sap volume in dormant sugar maples

    Science.gov (United States)

    William J. Gabriel; Russell S. Walters; Donald W. Seegrist

    1972-01-01

    Sap-flow rate is closely correlated with the sap volume produced by dormant sugar maple trees (Acer saccharum Marsh.) and could be used in making phenotypic selections of trees for superior sap production.

  15. The effects of antioxidant vitamin supplementation on expiratory flow rates at rest and during exercise.

    Science.gov (United States)

    Chenoweth, Leonie M; Smith, Joshua R; Ferguson, Christine S; Downey, Amy E; Harms, Craig A

    2015-10-01

    Previous studies suggest that pulmonary function is associated with fruit and vegetable consumption and plasma concentrations of antioxidant vitamins. Also, expiratory flow limitation (EFL) has been reported to limit ventilation during exercise in healthy individuals. We hypothesized antioxidant vitamin supplementation (AVS) would increase resting expiratory flow rates in healthy subjects and reduce EFL during exercise. Ten healthy, nonsmoking subjects (5 M/5 W), consuming flow rates (FEF25-75, FEF50) by ~9%. Following AVS, %EFL was significantly reduced by ~15% at minute 15, 20, and end-exercise with no change (p > 0.05) in end-expiratory lung volumes. Breathing frequency and ratings of perceived exertion and dyspnea were also lower (p 0.05) were evident at rest or during exercise with PLA. These results suggest that AVS can increase TAS, improve resting expiratory flow rates and reduce EFL during exercise in healthy subjects who are not meeting fruit and vegetable recommendations.

  16. Oral glucose retention, saliva viscosity and flow rate in 5-year-old children.

    Science.gov (United States)

    Negoro, M; Nakagaki, H; Tsuboi, S; Adachi, K; Hanaki, M; Tanaka, D; Takami, Y; Nakano, T; Kuwahara, M; Thuy, T T

    2000-11-01

    There are significant differences of glucose retention in site-specificity and individuals. Sixty-two 5-year-old nursery schoolchildren participated in this study on the relation between the viscosity of saliva and flow rate and glucose retention. Each child was instructed to rinse his/her mouth with a glucose solution (0.5 M, 5 ml) and then to spit out. Three minutes after rinsing, glucose retention was determined. Resting saliva was collected by a natural outflow method, then the flow rate was determined. A rotational viscometer was used to determine the viscosity. Glucose retention and flow rate were correlated at the left maxillary primary molars, and glucose retention and viscosity were correlated at the maxillary central primary incisors. It was concluded that glucose retention after glucose mouth rinsing was site-specific, and that glucose retention and the index of decayed, missing and filled primary teeth (dmft) were slightly correlated with the salivary viscosity and flow rate.

  17. The effect of carbon dioxide flow rate on the euthanasia of laboratory mice

    National Research Council Canada - National Science Library

    Moody, CM; Chua, B; Weary, DM

    2014-01-01

    .... Sensations of dyspnea may explain why rodents find CO2 concentrations >3% aversive. This study aimed to assess the effect of CO2 flow rates on time between the onset of dyspnea and various measures of insensibility...

  18. Potential of aeration flow rate and bio-char addition to reduce greenhouse gas and ammonia emissions during manure composting

    DEFF Research Database (Denmark)

    Chowdhury, Md Albarune; de Neergaard, Andreas; Jensen, Lars Stoumann

    2014-01-01

    Aeration is an important factor influencing CO2, CH4, N2O and NH3 emissions from the composting process. Both CH4 and N2O are potent greenhouse gases (GHG) of high importance. Here, we examined the effects of high and low aeration rates together with addition of barley straw with and without bio...... to composting hen manure and barley straw at low flow rates proved most effective in reducing cumulative NH3 and CH4 losses. Addition of bio-char in combination with barley straw to hen manure at both high and low flow rates reduced total GHG emissions (as CO2-equivalents) by 27-32% compared with barley straw...

  19. High energy density redox flow device

    Energy Technology Data Exchange (ETDEWEB)

    Carter, W. Craig; Chiang, Yet-Ming; Duduta, Mihai; Limthongkul, Pimpa

    2017-04-04

    Redox flow devices are described including a positive electrode current collector, a negative electrode current collector, and an ion-permeable membrane separating said positive and negative current collectors, positioned and arranged to define a positive electroactive zone and a negative electroactive zone; wherein at least one of said positive and negative electroactive zone comprises a flowable semi-solid composition comprising ion storage compound particles capable of taking up or releasing said ions during operation of the cell, and wherein the ion storage compound particles have a polydisperse size distribution in which the finest particles present in at least 5 vol % of the total volume, is at least a factor of 5 smaller than the largest particles present in at least 5 vol % of the total volume.

  20. Study of Low Flow Rate Ladle Bottom Gas Stirring Using Triaxial Vibration Signals

    Science.gov (United States)

    Yenus, Jaefer; Brooks, Geoffrey; Dunn, Michelle; Li, Zushu; Goodwin, Tim

    2018-02-01

    Secondary steelmaking plays a great role in enhancing the quality of the final steel product. The metal quality is a function of metal bath stirring in ladles. The metal bath is often stirred by an inert gas to achieve maximum compositional and thermal uniformity throughout the melt. Ladle operators often observe the top surface phenomena, such as level of meniscus disturbance, to evaluate the status of stirring. However, this type of monitoring has significant limitations in assessing the process accurately especially at low gas flow rate bubbling. The present study investigates stirring phenomena using ladle wall triaxial vibration at a low flow rate on a steel-made laboratory model and plant scale for the case of the vacuum tank degasser. Cold model and plant data were successfully modeled by partial least-squares regression to predict the amount of stirring. In the cold model, it was found that the combined vibration signal could predict the stirring power and recirculation speed effectively in specific frequency ranges. Plant trials also revealed that there is a high structure in each data set and in the same frequency ranges at the water model. In the case of industrial data, the degree of linear relationship was strong for data taken from a single heat.

  1. Measuring and modelling air mass flow rate in the injection stretch blow moulding process

    OpenAIRE

    Salomeia, Y.; Menary, G. H.; Armstrong, C G; Nixon, J; S. Yan

    2016-01-01

    The injection stretch blow moulding process involves the inflation and stretching of a hot preform into a mould to form bottles. A critical process variable and an essential input for process simulations is the rate of pressure increase within the preform during forming, which is regulated by an air flow restrictor valve. The paper describes a set of experiments for measuring the air flow rate within an industrial ISBM machine and the subsequent modelling of it with the FEA package ABAQUS. Tw...

  2. Long-Run Determinants of the Real Exchange Rate; A Stock-Flow Perspective

    OpenAIRE

    Hamid Faruqee

    1994-01-01

    This paper examines the long-run determinants of the real exchange rate from a stock-flow perspective. The empirical analysis estimates a long-run relationship between the real exchange rate, net foreign assets, and other factors affecting trade flows. Using postwar data for the United States and Japan, cointegration analysis supports the finding that the structural factors underlying each country's net trade and net foreign asset positions determine the long-run path for the real value of th...

  3. The effect of carbon dioxide flow rate on the euthanasia of laboratory mice.

    Science.gov (United States)

    Moody, C M; Chua, B; Weary, D M

    2014-10-01

    Laboratory rodents are commonly euthanized by exposure to gradually increasing concentrations of carbon dioxide (CO2). Current recommended flow rates range between 10 and 30% chamber vol/min and result in insensibility before exposure to painful concentrations (humans dyspnea is associated with a negative affective experience. Sensations of dyspnea may explain why rodents find CO2 concentrations >3% aversive. This study aimed to assess the effect of CO2 flow rates on time between the onset of dyspnea and various measures of insensibility (recumbency, loss of the righting reflex and loss of the pedal withdrawal reflex) to identify flow rates that minimize the potential experience of dyspnea. The results of this study indicate that a flow rate of 50% chamber vol/min, while holding the CO2 cage concentration just below 40%, minimizes the interval between the onset of labored breathing and recumbency. Using a 50% flow rate this interval averaged (± SE) 30.3 ± 2.9 s versus 49.7 ± 2.9 s at 20% chamber vol/min (F3,22 = 7.83, P = 0.0013). Similarly, the interval between the onset of labored breathing and loss of the righting reflex averaged 38.2 ± 2.4 s at a flow rate of 50% versus 59.2 ± 2.4 s at 20% chamber vol/min of CO2 (F3,22 = 13.62, P < 0.0001). We conclude that higher flow rates reduce the duration of dyspnea, but even at the highest flow rate mice experience more than 30 s between the onset of dyspnea and the most conservative estimate of insensibility. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  4. Fluid-Structure Interaction Effects on Mass Flow Rates in Solid Rocket Motors

    Science.gov (United States)

    2015-09-02

    in Solid Rocket Motors 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) William Harrigan 5d. PROJECT NUMBER...Determination of mass flow rate in a solid rocket motor is critical in the design of a new motor due to its effect on the thrust produced. Fluid...mass flow rates. The FSI analyses with two‐way coupling provided a more accurate assessment of solid rocket motor internal ballistics. 15. SUBJECT

  5. Gas flow rate dependence of the discharge characteristics of a helium atmospheric pressure plasma jet interacting with a substrate

    Science.gov (United States)

    Yan, Wen; Economou, Demetre J.

    2017-10-01

    A 2D (axisymmetric) computational study of the discharge characteristics of an atmospheric pressure plasma jet as a function of gas flow rate was performed. The helium jet emerged from a dielectric tube, with an average gas flow velocity in the range 2.5-20 m s-1 (1 atm, 300 K) in a nitrogen ambient, and impinged on a substrate a short distance dowstream. The effect of the substrate conductivity (conductror versus insulator) was also studied. Whenever possible, simulation predictions were compared with published experimental observations. Discharge ignition and propagation in the dielectric tube were hardly affected by the He gas flow velocity. Most properties of the plasma jet, however, depended sensitively on the He gas flow velocity, which determined the concentration distributions of helium and nitrogen in the mixing layer forming in the gap between the tube exit and the substrate. At low gas flow velocity, the plasma jet evolved from a hollow (donut-shaped) feature to one where the maximum of electron density was on axis. When the gas flow velocity was high, the plasma jet maintained its hollow structure until it struck the substrate. For a conductive substrate, the radial ion fluxes to the surface were relatively uniform over a radius of ~0.4-0.8 mm, and the dominant ion flux was that of He+. For a dielectric substrate, the radial ion fluxes to the surface peaked on the symmetry axis at low He gas flow velocity, but a hollow ion flux distribution was observed at high gas flow velocity. At the same time, the main ion flux switched from N2+ to He2+ as the He gas flow velocity increased from a low to a high value. The diameter of the plasma ‘footprint’ on the substrate first increased with increasing He gas flow velocity, and eventually saturated with further increases in velocity.

  6. A Distributed Flow Rate Control Algorithm for Networked Agent System with Multiple Coding Rates to Optimize Multimedia Data Transmission

    Directory of Open Access Journals (Sweden)

    Shuai Zeng

    2013-01-01

    Full Text Available With the development of wireless technologies, mobile communication applies more and more extensively in the various walks of life. The social network of both fixed and mobile users can be seen as networked agent system. At present, kinds of devices and access network technology are widely used. Different users in this networked agent system may need different coding rates multimedia data due to their heterogeneous demand. This paper proposes a distributed flow rate control algorithm to optimize multimedia data transmission of the networked agent system with the coexisting various coding rates. In this proposed algorithm, transmission path and upload bandwidth of different coding rate data between source node, fixed and mobile nodes are appropriately arranged and controlled. On the one hand, this algorithm can provide user nodes with differentiated coding rate data and corresponding flow rate. On the other hand, it makes the different coding rate data and user nodes networked, which realizes the sharing of upload bandwidth of user nodes which require different coding rate data. The study conducts mathematical modeling on the proposed algorithm and compares the system that adopts the proposed algorithm with the existing system based on the simulation experiment and mathematical analysis. The results show that the system that adopts the proposed algorithm achieves higher upload bandwidth utilization of user nodes and lower upload bandwidth consumption of source node.

  7. Risk Factors for Reduced Salivary Flow Rate in a Japanese Population: The Hisayama Study

    Directory of Open Access Journals (Sweden)

    Kenji Takeuchi

    2015-01-01

    Full Text Available The purpose of this study was to determine distinct risk factors causing reduced salivary flow rate in a community-dwelling population using a prospective cohort study design. This was a 5-year follow-up survey of 1,377 community-dwelling Japanese individuals aged ≥40 years. The salivary flow rate was evaluated at baseline and follow-up by collecting stimulated saliva. Data on demographic characteristics, use of medication, and general and oral health status were obtained at baseline. The relationship between reduced salivary flow rate during the follow-up period and its predictors was evaluated after adjustment for confounding factors. In a multivariate logistic regression model, higher age and plaque score and lower serum albumin levels were significantly associated with greater odds of an obvious reduction in salivary flow rate (age per decade, odds ratio [OR] = 1.25, 95% confidence interval [CI] = 1.03–1.51; serum albumin levels <4 g/dL, OR = 1.60, 95% CI = 1.04–2.46; plaque score ≥1, OR = 1.53, 95% CI = 1.04–2.24. In a multivariate linear regression model, age and plaque score remained independently associated with the increased rate of reduced salivary flow. These results suggest that aging and plaque score are important predictors of reduced salivary flow rate in Japanese adults.

  8. Factors influencing the flow rate through a surgical defect in human fetal membranes.

    Science.gov (United States)

    Devlieger, R; Gratacos, E; Ardon, H; Vanstraelen, S; Deprest, J

    2002-03-01

    In order to determine factors influencing the flow rate trough a created defect in human fetal membranes, an ex vivo set-up was used with fetal membranes collected from patients undergoing Caesarean section at term. The membranes were secured at the bottom of a plastic tube and traumatised with needles ranging from 14-26 Gauges (Ga), under a hydrostatic pressure of 10 to 20 cm H(2)O and an angle of 45 degrees or 90 degrees. The column was filled with amniotic fluid or Hartmann's solution. The duration of the puncture was 1 s or the time it takes to aspirate 10 ml through the needle. The flow rate through the defect in the fetal membranes and size of the defect were measured. The flow rate and defect size increased with increasing diameter of the needle. Increasing the pressure in the column resulted in a significant linear increase in the flow rate. Replacing the saline solution with amniotic fluid did not result in significant changes in the measured flow rates, except for the small needle size (24 Ga). Increasing the duration of the puncture did not result in increased flow rates, except for small needle size (24 Ga). These experiments suggest that needle diameter, angle of needle insertion, duration of the procedure, amniotic fluid pressure and composition could influence the incidence of amniotic fluid leakage following amniocentesis. Copyright 2002 John Wiley & Sons, Ltd.

  9. High temperature flow behaviour of SiC reinforced lithium ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The compressive flow behaviour of lithium aluminosilicate (LAS) glass, with and without SiC particulate reinforcements, was studied. The LAS glass crystallized to β spodumene during high-temperature testing. The flow behaviour of LAS glass changed from Newtonian to non-Newtonian due to the presence of.

  10. Association beween resting heart rate, shear and flow-mediated dilation in healthy adults.

    Science.gov (United States)

    Fox, Brandon M; Brantley, Lucy; White, Claire; Seigler, Nichole; Harris, Ryan A

    2014-10-01

    Preclinical data have demonstrated that heart rate (HR) can directly impact vascular endothelial function, in part, through a shear-stress mechanism. This study sought to explore, in humans, the associations between resting heart rate and both shear and endothelial function assessed by flow-mediated dilation (FMD). The brachial artery FMD test was performed in 31 apparently healthy volunteers. Basal (B) and hyperaemic (H) shear were quantified in the following two ways using data from the FMD test: the traditional cumulative shear area under the curve up to peak dilation (Shearcum) method; and our novel method of shear summation (Shearsum), which accounts for HR by summing each individual cardiac cycle shear up to peak dilation. Data were grouped by tertiles based on resting HR as follows: low (LHR = 43-56 beats min(-1); n = 10); middle (MHR = 58-68 beats min(-1); n = 11); and high (HHR = 69-77 beats min(-1); n = 10). Within the LHR group, both B-Shearcum and H-Shearcum were significantly higher (P heart rate and both shear and endothelial function in humans. Moreover, these findings have implications for considering heart rate as an important physiological variable when quantifying shear and performing the FMD test. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

  11. Effects of air flow rate on the oxidation of NBG-18 and NBG-25 nuclear graphite

    Science.gov (United States)

    Chi, Se-Hwan; Chan Kim, Gen

    2017-08-01

    The effects of air flow rate (FR) (FR range: 1-10 L/min) on the oxidation of NBG-18 and NBG-25 nuclear graphite grades at temperatures between 600 and 1100 °C were studied, in reference to the standard test procedure for measuring oxidation rates of nuclear graphite in air (ASTM D 7542-09). The results showed that the FR effects on oxidation rate (OR) increase with increasing temperature with negligible FR effects at 600 °C for both materials. At high temperatures (>800 °C) there appears to be a two-stage relationship between FR and OR, which corresponds to the transition between reaction rates dominated by chemical kinetics and those dominated by diffusion. The material-specific microstructure appeared strongly influences this transition. The overall OR-FR behaviours of NBG-18 were higher than NBG-25 at 600-800 °C while negligible differences in the OR-FR behaviours between the two grades were observed at 900-1100 °C. The mercury porosimetry data showed that the higher OR-FR behaviours observed in NBG-18 may partly be attributed to the differences in the pore size distribution (open porosity and cumulative pore area) between the grades, especially for the large size pores (diameter ≫ 5 × 103 nm).

  12. Magnetic resonance measurement of blood and CSF flow rates with phase contrast--normal values, repeatability and CO2 reactivity.

    Science.gov (United States)

    Piechnik, Stefan K; Summers, Paul E; Jezzard, Peter; Byrne, James V

    2008-01-01

    Similarity in flow pulsatility has been proposed as a basis for semi-automated segmentation of vessel lumens for MR-based flow measurement, but re-examinations of salient aspects of the methodology have not been widely reported. 12 normal control subjects underwent repeated (3*Baseline+1*5%CO2) phase contrast measurements of CSF flow through the cerebral aqueduct and foramen magnum, and CBF through the 6 large cranial vessels at the level of the 1st vertebra. Average flows were calculated for regions temporally correlated (0.3 < or = Rthreshold < or = 0.95) to user defined seed points and their 3 x 3 neighbours. Arterial CBF averaged 710ml/min, with low variability (+/- 4%/17%, intra-individual/group CV respectively) and was the only flow to respond significantly to 5%/mmHg CO2. Venous outflow was much smaller (298ml/min +/- 10%/ 72%), possibly due to the weak venous pulse and variable venous anatomy. Average CSF flows exceeded the classical 0.4ml/min CSF production rate and were highly variable--aqueduct: 0.6ml/min (+/- 50%/93%), foramen magnum: -2.7ml/min (+/- 158%/226%). This preliminary analysis identified procedural steps that can improve the accuracy and repeatability of MR flow measurements, but the process remains user-dependent for the weakly pulsatile foramen magnum CSF and venous flows where variability remains a significant confound even to relatively large perturbations such as CO2 administration.

  13. Core surface flow modelling from high-resolution secular variation

    DEFF Research Database (Denmark)

    Holme, R.; Olsen, Nils

    2006-01-01

    -flux hypothesis, but the spectrum of the SV implies that a conclusive test of frozen-flux is not possible. We parametrize the effects of diffusion as an expected misfit in the flow prediction due to departure from the frozen-flux hypothesis; at low spherical harmonic degrees, this contribution dominates...... the expected departure of the SV predictions from flow to the observed SV, while at high degrees the SV model uncertainty is dominant. We construct fine-scale core surface flows to model the SV. Flow non-uniqueness is a serious problem because the flows are sufficiently small scale to allow flow around non......-series of magnetic data and better parametrization of the external magnetic field....

  14. Impact of flow rate on lactate uptake and gluconeogenesis in glucagon-stimulated perfused livers.

    Science.gov (United States)

    Sumida, Ken D; Urdiales, Jerry H; Donovan, Casey M

    2006-01-01

    The impact of reduced hepatic flow on lactate uptake and gluconeogenesis was examined in isolated glucagon-stimulated perfused livers from 24-h-fasted rats. After surgical isolation, livers were perfused (single pass) for 30 min with Krebs-Henseleit (KH) bicarbonate buffer, fresh bovine erythrocytes (hematocrit approximately 20%), and no added substrate. After this "washout" period, steady-state perfusions were initiated with a second reservoir containing the KH buffer, bovine erythrocytes, [U-(14)C]lactate (10,000 dpm/ml), lactate (2.5 mM), and glucagon (250 microg/ml). Perfusion flow rate was adjusted to one of five rates (i.e., 1.8, 2.7, 3.9, 7.4, and 11.0 ml.min(-1).100 g body wt(-1)). After the perfusion, the liver was dissected out and weighed so as to establish the actual flow rate per gram of liver. The resulting flow rates ranged from 0.52 to 4.03 ml.min(-1).g liver(-1). As a function of flow rate, lactate uptake rose in a hyperbolic fashion to an apparent plateau of 2.34 micromol.min(-1).g liver(-1). Fractional extraction (FX) of lactate from the perfusate demonstrated an exponential decline with increased flow rates (r=0.97). At flow rates above 1.0 ml.min(-1).g liver(-1), adjustments in FX compensated for changes in lactate delivery, resulting in steady rates of lactate uptake and gluconeogenesis. Below 1.0.min(-1).g liver(-1) the increased FX was unable to compensate for the decline in lactate delivery and lactate uptake declined rapidly. Gluconeogenesis demonstrated similar kinetics to lactate uptake, reflecting its dominant role among pathways for lactate removal under the current conditions.

  15. Modeling Flow Rate to Estimate Hydraulic Conductivity in a Parabolic Ceramic Water Filter

    Directory of Open Access Journals (Sweden)

    Ileana Wald

    2012-01-01

    Full Text Available In this project we model volumetric flow rate through a parabolic ceramic water filter (CWF to determine how quickly it can process water while still improving its quality. The volumetric flow rate is dependent upon the pore size of the filter, the surface area, and the height of water in the filter (hydraulic head. We derive differential equations governing this flow from the conservation of mass principle and Darcy's Law and find the flow rate with respect to time. We then use methods of calculus to find optimal specifications for the filter. This work is related to the research conducted in Dr. James R. Mihelcic's Civil and Environmental Engineering Lab at USF.

  16. Salivary flow rate and pH during prolonged gum chewing in humans.

    Science.gov (United States)

    Polland, K E; Higgins, F; Orchardson, R

    2003-09-01

    Gum chewing for 20 min causes an increase in salivary flow rate and salivary pH. Most people chew gum for longer than 20 min, and our aim was to determine how whole mouth salivary flow rate and pH might adapt during prolonged gum chewing. Resting saliva was collected over 5 min; gum-stimulated saliva was collected at intervals during 90 min, chewing a single pellet (1.5 g) of mint-flavoured, sugar-free gum (n = 19). Subjects chewed at their own preferred rate and style. Both salivary flow rate and pH were increased above resting levels for the entire 90 min. The salivary flow was significantly greater (anovaP chewing. The saliva pH remained significantly higher (P pH even after 90-min chewing. When the experiment was repeated with the gum pellets replaced at 30 and 60 min (n = 9), similar increases in salivary flow rate and pH were found. In the latter experiment, there was no evidence of any cumulative effects on flow or pH. The persistent increase in salivary pH in particular could be beneficial to oral and dental health.

  17. Evaporation of polydispersed droplets in a highly turbulent channel flow

    Energy Technology Data Exchange (ETDEWEB)

    Cochet, M.; Bazile, Rudy; Ferret, B.; Cazin, S. [INPT, UPS, IMFT (Institut de Mecanique des Fluides de Toulouse), Universite de Toulouse (France)

    2009-09-15

    A model experiment for the study of evaporating turbulent two-phase flows is presented here. The study focuses on a situation where pre-atomized and dispersed droplets vaporize and mix in a heated turbulent flow. The test bench consists in a channel flow with characteristics of homogeneous and isotropic turbulence where fluctuations levels reach very high values (25% in the established zone). An ultrasonic atomizer allows the injection of a mist of small droplets of acetone in the carrier flow. The large range diameters ensure that every kind of droplet behavior with regards to turbulence is possible. Instantaneous concentration fields of the vaporized phase are extracted from fluorescent images (PLIF) of the two phase flow. The evolution of the mixing of the acetone vapor is analyzed for two different liquid mass loadings. Despite the high turbulence levels, concentration fluctuations remain significant, indicating that air and acetone vapor are not fully mixed far from the injector. (orig.)

  18. High-temperature plastic flow behaviour in the binder of WC-Co cemented carbides

    Science.gov (United States)

    Lee, In-Chul

    1996-04-01

    Co-rich solid solution alloys regarded as the composition of binder phasesat elevated temperatures in WC-Co cemented carbides were fabricated and the high-temperature deformation behaviour of the alloys was investigated. The logarithmic relationship between flow stress and strain rate is expressed by a single straight line with the slope of 0.15 at a constant temperature in all strain rate range examined, unlike in cemented carbides showing the sigmoidal behaviour. The solid solution hardening due to the addition of Cr3C2 and VC is negligible in the Co-9WC-lCr3C2-0.5VC alloy and the mutual relation in flow stress is different between the cemented carbides and their binder phases in region I. The plastic flow in region I in WC-Co cemented carbides cannot be explained by the flow stress or flow behaviour in the binder phase.

  19. Technical characterization of dialysis fluid flow and mass transfer rate in dialyzers with various filtration coefficients using dimensionless correlation equation.

    Science.gov (United States)

    Fukuda, Makoto; Yoshimura, Kengo; Namekawa, Koki; Sakai, Kiyotaka

    2017-06-01

    The objective of the present study is to evaluate the effect of filtration coefficient and internal filtration on dialysis fluid flow and mass transfer coefficient in dialyzers using dimensionless mass transfer correlation equations. Aqueous solution of vitamin B12 clearances were obtained for REXEED-15L as a low flux dialyzer, and APS-15EA and APS-15UA as high flux dialyzers. All the other design specifications were identical for these dialyzers except for filtration coefficient. The overall mass transfer coefficient was calculated, moreover, the exponents of Reynolds number (Re) and film mass transfer coefficient of the dialysis-side fluid (k D) for each flow rate were derived from the Wilson plot and dimensionless correlation equation. The exponents of Re were 0.4 for the low flux dialyzer whereas 0.5 for the high flux dialyzers. Dialysis fluid of the low flux dialyzer was close to laminar flow because of its low filtration coefficient. On the other hand, dialysis fluid of the high flux dialyzers was assumed to be orthogonal flow. Higher filtration coefficient was associated with higher k D influenced by mass transfer rate through diffusion and internal filtration. Higher filtration coefficient of dialyzers and internal filtration affect orthogonal flow of dialysis fluid.

  20. High order Poisson Solver for unbounded flows

    DEFF Research Database (Denmark)

    Hejlesen, Mads Mølholm; Rasmussen, Johannes Tophøj; Chatelain, Philippe

    2015-01-01

    This paper presents a high order method for solving the unbounded Poisson equation on a regular mesh using a Green’s function solution. The high order convergence was achieved by formulating mollified integration kernels, that were derived from a filter regularisation of the solution field....... The method was implemented on a rectangular domain using fast Fourier transforms (FFT) to increase computational efficiency. The Poisson solver was extended to directly solve the derivatives of the solution. This is achieved either by including the differential operator in the integration kernel...... or by performing the differentiation as a multiplication of the Fourier coefficients. In this way, differential operators such as the divergence or curl of the solution field could be solved to the same high order convergence without additional computational effort. The method was applied and validated using...

  1. Towards a high-resolution flow camera using artificial hair sensor arrays for flow pattern observations.

    Science.gov (United States)

    Dagamseh, A M K; Wiegerink, R J; Lammerink, T S J; Krijnen, G J M

    2012-12-01

    Flow-sensor arrays uncover the potential to measure spatio-temporal flow patterns rather than flow measurements at just a single point. We present in this paper the developments in design, fabrication and interfacing of biomimetic flow-sensor arrays, inspired by flow-sensitive organs (cerci) of crickets. For the purpose of high-resolution flow field visualization by our artificial hair flow-sensor arrays, various array-interfacing schemes are discussed and compared. Frequency division multiplexing (FDM) is shown to be an attractive method for efficient interrogation of capacitive array sensors. Using silicon-on-insulator technology with deep trench isolation structures, hair-based flow-sensors with differential capacitive read-out, arranged in single-chip arrays, have been successfully fabricated. FDM is implemented and used to interrogate individual hair sensors providing simultaneous real-time flow measurements from multiple hairs. This powerful approach is demonstrated by reconstruction of the field of a harmonic dipole field at the position of the hairs and by localizing this dipole source relative to the array elements.

  2. Investigation on the Core Bypass Flow in a Very High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Yassin

    2013-10-22

    Uncertainties associated with the core bypass flow are some of the key issues that directly influence the coolant mass flow distribution and magnitude, and thus the operational core temperature profiles, in the very high-temperature reactor (VHTR). Designers will attempt to configure the core geometry so the core cooling flow rate magnitude and distribution conform to the design values. The objective of this project is to study the bypass flow both experimentally and computationally. Researchers will develop experimental data using state-of-the-art particle image velocimetry in a small test facility. The team will attempt to obtain full field temperature distribution using racks of thermocouples. The experimental data are intended to benchmark computational fluid dynamics (CFD) codes by providing detailed information. These experimental data are urgently needed for validation of the CFD codes. The following are the project tasks: • Construct a small-scale bench-top experiment to resemble the bypass flow between the graphite blocks, varying parameters to address their impact on bypass flow. Wall roughness of the graphite block walls, spacing between the blocks, and temperature of the blocks are some of the parameters to be tested. • Perform CFD to evaluate pre- and post-test calculations and turbulence models, including sensitivity studies to achieve high accuracy. • Develop the state-of-the art large eddy simulation (LES) using appropriate subgrid modeling. • Develop models to be used in systems thermal hydraulics codes to account and estimate the bypass flows. These computer programs include, among others, RELAP3D, MELCOR, GAMMA, and GAS-NET. Actual core bypass flow rate may vary considerably from the design value. Although the uncertainty of the bypass flow rate is not known, some sources have stated that the bypass flow rates in the Fort St. Vrain reactor were between 8 and 25 percent of the total reactor mass flow rate. If bypass flow rates are on the

  3. Computational analysis of high-throughput flow cytometry data.

    Science.gov (United States)

    Robinson, J Paul; Rajwa, Bartek; Patsekin, Valery; Davisson, Vincent Jo

    2012-08-01

    Flow cytometry has been around for over 40 years, but only recently has the opportunity arisen to move into the high-throughput domain. The technology is now available and is highly competitive with imaging tools under the right conditions. Flow cytometry has, however, been a technology that has focused on its unique ability to study single cells and appropriate analytical tools are readily available to handle this traditional role of the technology. Expansion of flow cytometry to a high-throughput (HT) and high-content technology requires both advances in hardware and analytical tools. The historical perspective of flow cytometry operation as well as how the field has changed and what the key changes have been discussed. The authors provide a background and compelling arguments for moving toward HT flow, where there are many innovative opportunities. With alternative approaches now available for flow cytometry, there will be a considerable number of new applications. These opportunities show strong capability for drug screening and functional studies with cells in suspension. There is no doubt that HT flow is a rich technology awaiting acceptance by the pharmaceutical community. It can provide a powerful phenotypic analytical toolset that has the capacity to change many current approaches to HT screening. The previous restrictions on the technology, based on its reduced capacity for sample throughput, are no longer a major issue. Overcoming this barrier has transformed a mature technology into one that can focus on systems biology questions not previously considered possible.

  4. Computational analysis of high-throughput flow cytometry data

    Science.gov (United States)

    Robinson, J Paul; Rajwa, Bartek; Patsekin, Valery; Davisson, Vincent Jo

    2015-01-01

    Introduction Flow cytometry has been around for over 40 years, but only recently has the opportunity arisen to move into the high-throughput domain. The technology is now available and is highly competitive with imaging tools under the right conditions. Flow cytometry has, however, been a technology that has focused on its unique ability to study single cells and appropriate analytical tools are readily available to handle this traditional role of the technology. Areas covered Expansion of flow cytometry to a high-throughput (HT) and high-content technology requires both advances in hardware and analytical tools. The historical perspective of flow cytometry operation as well as how the field has changed and what the key changes have been discussed. The authors provide a background and compelling arguments for moving toward HT flow, where there are many innovative opportunities. With alternative approaches now available for flow cytometry, there will be a considerable number of new applications. These opportunities show strong capability for drug screening and functional studies with cells in suspension. Expert opinion There is no doubt that HT flow is a rich technology awaiting acceptance by the pharmaceutical community. It can provide a powerful phenotypic analytical toolset that has the capacity to change many current approaches to HT screening. The previous restrictions on the technology, based on its reduced capacity for sample throughput, are no longer a major issue. Overcoming this barrier has transformed a mature technology into one that can focus on systems biology questions not previously considered possible. PMID:22708834

  5. The role of unsteady effusion rates on inflation in long-lived lava flow fields

    Science.gov (United States)

    Rader, E.; Vanderkluysen, L.; Clarke, A.

    2017-11-01

    The emission of volcanic gases and particles can have global and lasting environmental effects, but their timing, tempo, and duration can be problematic to quantify for ancient eruptions where real-time measurements are absent. Lava flows, for example, may be long-lasting, and their impact is controlled by the rate, tempo, and vigor of effusion. These factors are currently difficult to derive from the geologic record but can have large implications for the atmospheric impact of an eruption. We conducted a set of analogue experiments on lava flow inflation aiming at connecting lava morphologies preserved in the rock record to eruption tempo and dynamics through pulsating effusion rates. Inflation, a process where molten material is injected beneath the crust of an active lava flow and lifts it upwards, is a common phenomenon in basaltic volcanic systems. This mechanism requires three components: a) a coherent, insulating crust; b) a wide-spread molten core; and c) pressure built up beneath the crust from a sustained supply of molten material. Inflation can result in a lava flow growing tens of meters thick, even in flow fields that expand hundreds of square kilometers. It has been documented that rapid effusion rates tend to create channels and tubes, isolating the active part of the flow from the stagnant part, while slow effusion rates may cause crust to form quickly and seize up, forcing lava to overtop the crust. However, the conditions that allow for inflation of large flow fields have not previously been evaluated in terms of effusion rate. By using PEG 600 wax and a programmable pump, we observe how, by pulsating effusion rate, inflation occurs even in very low viscosity basaltic eruptions. We show that observations from inflating Hawaiian lava flows correlate well with experimental data and indicate that instantaneous effusion rates may have been 3 times higher than average effusion rates during the emplacement of the 23 January 1988 flow at Kīlauea (Hawai

  6. Unchanged cerebral blood flow and oxidative metabolism after acclimatization to high altitude

    DEFF Research Database (Denmark)

    Møller, Kirsten; Paulson, Olaf B; Hornbein, Thomas F.

    2002-01-01

    . Global cerebral blood flow at rest and during exercise on a bicycle ergometer was measured by the Kety-Schmidt technique. Cerebral metabolic rates of oxygen, glucose, and lactate were calculated by the Fick principle. Cerebral function was assessed by a computer-based measurement of reaction time...... and cerebral metabolic rates of oxygen and glucose also remained unchanged, whereas cerebral metabolic rates of lactate increased slightly but nonsignificantly at high altitude during exercise compared with high altitude at rest. Reaction time was unchanged. The data indicate that cerebral blood flow......The authors investigated the effect of acclimatization to high altitude on cerebral blood flow and oxidative metabolism at rest and during exercise. Nine healthy, native sea-level residents were studied 3 weeks after arrival at Chacaltaya, Bolivia (5,260 m) and after reacclimatization to sea level...

  7. Potential of aeration flow rate and bio-char addition to reduce greenhouse gas and ammonia emissions during manure composting.

    Science.gov (United States)

    Chowdhury, Md Albarune; de Neergaard, Andreas; Jensen, Lars Stoumann

    2014-02-01

    Aeration is an important factor influencing CO2, CH4, N2O and NH3 emissions from the composting process. Both CH4 and N2O are potent greenhouse gases (GHG) of high importance. Here, we examined the effects of high and low aeration rates together with addition of barley straw with and without bio-char on GHG and NH3 emissions from composting cattle slurry and hen manure in small-scale laboratory composters. Depending on treatment, cumulative C losses via CO2 and CH4 emissions accounted for 11.4-22.5% and 0.004-0.2% of initial total carbon, while N losses as N2O and NH3 emissions comprised 0.05-0.1% and 0.8-26.5% of initial total nitrogen, respectively. Decreasing the flow rate reduced cumulative NH3 losses non-significantly (by 88%) but significantly increased CH4 losses (by 51%) from composting of cattle slurry with barley straw. Among the hen manure treatments evaluated, bio-char addition to composting hen manure and barley straw at low flow rates proved most effective in reducing cumulative NH3 and CH4 losses. Addition of bio-char in combination with barley straw to hen manure at both high and low flow rates reduced total GHG emissions (as CO2-equivalents) by 27-32% compared with barley straw addition alone. Comparisons of flow rates showed that low flow could be an alternative strategy for reducing NH3 losses without any significant change in N2O emissions, pointing to the need for well-controlled composting conditions if gaseous emissions are to be minimised. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. A Computational Framework to Optimize Subject-Specific Hemodialysis Blood Flow Rate to Prevent Intimal Hyperplasia

    Science.gov (United States)

    Mahmoudzadeh, Javid; Wlodarczyk, Marta; Cassel, Kevin

    2017-11-01

    Development of excessive intimal hyperplasia (IH) in the cephalic vein of renal failure patients who receive chronic hemodialysis treatment results in vascular access failure and multiple treatment complications. Specifically, cephalic arch stenosis (CAS) is known to exacerbate hypertensive blood pressure, thrombosis, and subsequent cardiovascular incidents that would necessitate costly interventional procedures with low success rates. It has been hypothesized that excessive blood flow rate post access maturation which strongly violates the venous homeostasis is the main hemodynamic factor that orchestrates the onset and development of CAS. In this article, a computational framework based on a strong coupling of computational fluid dynamics (CFD) and shape optimization is proposed that aims to identify the effective blood flow rate on a patient-specific basis that avoids the onset of CAS while providing the adequate blood flow rate required to facilitate hemodialysis. This effective flow rate can be achieved through implementation of Miller's surgical banding method after the maturation of the arteriovenous fistula and is rooted in the relaxation of wall stresses back to a homeostatic target value. The results are indicative that this optimized hemodialysis blood flow rate is, in fact, a subject-specific value that can be assessed post vascular access maturation and prior to the initiation of chronic hemodialysis treatment as a mitigative action against CAS-related access failure. This computational technology can be employed for individualized dialysis treatment.

  9. Acute short-term mental stress does not influence salivary flow rate dynamics.

    Directory of Open Access Journals (Sweden)

    Ella A Naumova

    Full Text Available BACKGROUND: Results of studies that address the influence of stress on salivary flow rate and composition are controversial. The aim of this study was to reveal the influence of stress vulnerability and different phases of stress reactivity on the unstimulated and stimulated salivary flow rate. We examined that acute mental stress does not change the salivary flow rate. In addition, we also examined the salivary cortisol and protein level in relation to acute mental stress stimuli. METHODS: Saliva of male subjects was collected for five minutes before, immediately, 10, 30 and 120 min after toothbrushing. Before toothbrushing, the subjects were exposed to acute stress in the form of a 2 min public speech. Salivary flow rate and total protein was measured. The physiological stress marker cortisol was analyzed using enzyme-linked immunosorbent assay. To determine the subjects' psychological stress reaction, the State-Trait-Anxiety Inventory State questionnaire (STAI data were obtained. The subjects were divided into stress subgroup (S1 (psychological reactivity, stress subgroup (S2 (psychological and physiological reactivity and a control group. The area under the curve for salivarycortisol concentration and STAI-State scores were calculated. All data underwent statistical analysis using one-way analysis of variance. RESULTS: Immediately after stress exposure, all participants exhibited a psychological stress reaction. Stress exposure did not change the salivary flow rate. Only 69% of the subjects continued to display a physiological stress reaction 20 minutes after the public talk. There was no significant change in the salivary flow rate during the psychological and the physiological stress reaction phases relative to the baseline. CONCLUSIONS: Acute stress has no impact on the salivary flow rate; however, there may be other responses through salivary proteins that are increased with the acute stress stimuli. Future studies are needed to examine

  10. Study on flow parameters of fractal porous media in the high-velocity fluid flow regime

    Science.gov (United States)

    Qi, Mei; Xu, Hui; Yang, Chao; Qu, Tailai; Kong, lingxiao; Wu, Shucheng; Zeng, Baoquan; Xu, Haixia

    2017-12-01

    High-velocity fluid flow, which will result in the region of the wellbore or fracture, is generally in the turbulent flow regime and has drawn tremendous attention in petroleum engineering field. Turbulent factor is the key parameter, which is widely used to describe high-velocity flow in porous media. In this work, a theoretical model for turbulent factor in fractal porous media in the high-velocity fluid flow regime is developed. Moreover, a novel analytical expression for the permeability in porous media based on Wu's resistance model is also derived. Then, the analytical Kozeny-Carman constant with no empirical constant is obtained. The predictions of permeability-porosity relation by the current mathematical models have been validated by comparing with available experimental data. Furthermore, the effects of structural parameters of porous media on the curve of velocity and pressure drop are discussed in detail.

  11. Contraction rate, flow modification and bed layering impact on scour at the elliptical guide banks

    Science.gov (United States)

    Gjunsburgs, B.; Jaudzems, G.; Bizane, M.; Bulankina, V.

    2017-10-01

    Flow contraction by the bridge crossing structures, intakes, embankments, piers, abutments and guide banks leads to general scour and the local scour in the vicinity of the structures. Local scour is depending on flow, river bed and structures parameters and correct understanding of the impact of each parameter can reduce failure possibility of the structures. The paper explores hydraulic contraction, the discharge redistribution between channel and floodplain during the flood, local flow modification and river bed layering on depth, width and volume of scour hole near the elliptical guide banks on low-land rivers. Experiments in a flume, our method for scour calculation and computer modelling results confirm a considerable impact of the contraction rate of the flow, the discharge redistribution between channel and floodplain, the local velocity, backwater and river bed layering on the depth, width, and volume of scour hole in steady and unsteady flow, under clear water condition. With increase of the contraction rate of the flow, the discharge redistribution between channel and floodplain, the local velocity, backwater values, the scour depth increases. At the same contraction rate, but at a different Fr number, the scour depth is different: with increase in the Fr number, the local velocity, backwater, scour depth, width, and volume is increasing. Acceptance of the geometrical contraction of the flow, approach velocity and top sand layer of the river bed for scour depth calculation as accepted now, may be the reason of the structures failure and human life losses.

  12. Dynamics of High Pressure Reacting Shear Flows

    Science.gov (United States)

    2015-10-02

    liquid rockets, future gas turbines • When the combustion systems are for propulsion, limited tankage dictates that on-board propellants be stored in...condensed form – eg, kerosene, liquid oxygen in rockets • Combustion systems can no longer be designed to meet modern requirements without considering...speed gaseous H2 Symmetric recirculation zones Low-speed liquid O2 High-speed gaseous H2 Asymmetric recirculation zones Combustion case Results

  13. Salivary flow rates measured during radiation therapy in head and neck cancer patients: a pilot study assessing salivary sediment formation.

    Science.gov (United States)

    Chambers, Mark S; Tomsett, Kelley L; Artopoulou, Ioli I; Garden, Adam S; El-Naggar, Adel K; Martin, Jack W; Keene, Harris J

    2008-08-01

    Xerostomia often occurs in patients being managed for head and neck cancer who receive radiation therapy. Although accurate salivary sampling can be therapeutically important to measure during radiation, sampling errors can occur because of salivary sediments. Determining the impact that salivary sediments have on measured salivary flow rates during radiation is important for management of patients. The purpose of this study was to assess the magnitude of error associated with the inclusion of nonsalivary components (sediment) in the calculation of whole stimulated saliva flow rates prior to and during radiation therapy (SS and SSR) in patients with head and neck cancer. Whole paraffin-stimulated saliva was collected in large-mouth centrifuge tubes from 20 patients with head and neck cancer prior to and during the third week of radiation therapy. Gravimetric methods were used to calculate the flow rates at g/5 min. After centrifugation, supernatant saliva was removed and the sediment was oven-dried to remove residual moisture. Sediment weight was subtracted from the original weight of saliva specimens and flow rates were recalculated. Means and standard deviations were determined and flow rate differences before (BC) and after (AC) sediment correction were evaluated statistically with the paired t test (alpha=.05). A nonparametric analysis of the flow rate data with the Wilcoxon matched-pairs signed-ranks test was also used to examine the magnitude and direction of the intrapair (BC-AC) differences (alpha=.05). On average, salivary sediment contributed less than 1% of the total uncorrected weight of saliva prior to radiation therapy. In specimens collected during radiation therapy, sediment contributed an average of 14% of the total uncorrected weight and as high as 95.4% in 1 patient. Sediment percentages were 20% and higher in 4 patients. In the Wilcoxon analysis, 19 out of 20 paired BC and AC flow rates were higher in the BC group in the SS and SSR samples. The

  14. Milk Flow Rates From Bottle Nipples Used for Feeding Infants Who Are Hospitalized

    Science.gov (United States)

    Park, Jinhee; Thoyre, Suzanne M.; Estrem, Hayley; Nix, W. Brant

    2015-01-01

    Purpose This study tested the milk flow rates and variability in flow of currently available nipples used for bottle-feeding infants who are hospitalized. Method Clinicians in 3 countries were surveyed regarding nipples available to them for feeding infants who are hospitalized. Twenty-nine nipple types were identified, and 10 nipples of each type were tested by measuring the amount of infant formula expressed in 1 min using a breast pump. Mean milk flow rate (mL/min) and coefficient of variation were used to compare nipples within brand and within category (i.e., Slow, Standard, Premature). Results Flow rates varied widely between nipples, ranging from 2.10 mL/min for the Enfamil Cross-Cut to 85.34 mL/min for the Dr. Brown's Y-Cut Standard Neck. Variability of flow rates among nipples of the same type ranged from a coefficient of variation of 0.05 for Dr. Brown's Level 1 Standard- and Wide-Neck to 0.42 for the Enfamil Cross-Cut. Mean coefficient of variation by brand ranged from 0.08 for Dr. Brown's to 0.36 for Bionix. Conclusions Milk flow is an easily manipulated variable that may contribute to the degree of physiologic instability experienced by infants who are medically fragile during oral feeding. This study provides clinicians with information to guide appropriate selection of bottle nipples for feeding infants who are hospitalized. PMID:26172340

  15. Milk Flow Rates From Bottle Nipples Used for Feeding Infants Who Are Hospitalized.

    Science.gov (United States)

    Pados, Britt F; Park, Jinhee; Thoyre, Suzanne M; Estrem, Hayley; Nix, W Brant

    2015-11-01

    This study tested the milk flow rates and variability in flow of currently available nipples used for bottle-feeding infants who are hospitalized. Clinicians in 3 countries were surveyed regarding nipples available to them for feeding infants who are hospitalized. Twenty-nine nipple types were identified, and 10 nipples of each type were tested by measuring the amount of infant formula expressed in 1 min using a breast pump. Mean milk flow rate (mL/min) and coefficient of variation were used to compare nipples within brand and within category (i.e., Slow, Standard, Premature). Flow rates varied widely between nipples, ranging from 2.10 mL/min for the Enfamil Cross-Cut to 85.34 mL/min for the Dr. Brown's Y-Cut Standard Neck. Variability of flow rates among nipples of the same type ranged from a coefficient of variation of 0.05 for Dr. Brown's Level 1 Standard- and Wide-Neck to 0.42 for the Enfamil Cross-Cut. Mean coefficient of variation by brand ranged from 0.08 for Dr. Brown's to 0.36 for Bionix. Milk flow is an easily manipulated variable that may contribute to the degree of physiologic instability experienced by infants who are medically fragile during oral feeding. This study provides clinicians with information to guide appropriate selection of bottle nipples for feeding infants who are hospitalized.

  16. On rating curve variability in presence of movable bed and unsteady flow. Applications to Tuscan rivers.

    Science.gov (United States)

    Minatti, Lorenzo; Nicoletta De Cicco, Pina; Paris, Enio

    2014-05-01

    In common engineering practice, rating curves are obtained from direct stage-discharge measurements or, more often, from stage measurements coupled with flow simulations. The present work mainly focuses on the latter technique, where stage-measuring gauges are usually installed on bridges with flow conditions likely to be influenced by local geometry constraints. In such cases, backwater flow and flow transition to supercritical state may occur, influencing sediment transport capacity and triggering more intense changes in river morphology. The unsteadiness of the flow hydrograph may play an important role too, according to the velocity of its rising and falling limbs. Nevertheless, the simulations conducted to build a rating curve are often carried out with steady flow and fixed bed conditions where the afore-mentioned effects are not taken into account at all. Numerical simulations with mobile bed and different unsteady flow conditions have been conducted on some real case studies in the rivers of Tuscany (Italy), in order to assess how rating curves change with respect to the "standard" one (that is, the classical steady flow rating curve). A 1D finite volume numerical model (REMo, River Evolution Modeler) has been employed for the simulations. The model solves the 1D Shallow Water equations coupled with the sediments continuity equation in composite channels, where the overbanks are treated with fixed bed conditions while the main channel can either aggrade or be scoured. The model employs an explicit scheme with 2nd order accuracy in both space and time: this allows the correct handling of moderately stiff source terms via a local corrector step. Such capability is very important for the applications of the present work as it allows the modelling of abrupt contractions and jumps in bed bottom elevations which often occur near bridges. The outcomes of the simulations are critically analyzed in order to provide a first insight on the conditions inducing

  17. High-Flow Jet Exit Rig Designed and Fabricated

    Science.gov (United States)

    Buehrle, Robert J.; Trimarchi, Paul A.

    2003-01-01

    The High-Flow Jet Exit Rig at the NASA Glenn Research Center is designed to test single flow jet nozzles and to measure the appropriate thrust and noise levels. The rig has been designed for the maximum hot condition of 16 lbm/sec of combustion air at 1960 R (maximum) and to produce a maximum thrust of 2000 lb. It was designed for cold flow of 29.1 lbm/sec of air at 530 R. In addition, it can test dual-flow nozzles (nozzles with bypass flow in addition to core flow) with independent control of each flow. The High- Flow Jet Exit Rig was successfully fabricated in late 2001 and is being readied for checkout tests. The rig will be installed in Glenn's Aeroacoustic Propulsion Laboratory. The High-Flow Jet Exit Rig consists of the following major components: a single component force balance, the natural-gas-fueled J-79 combustor assembly, the plenum and manifold assembly, an acoustic/instrumentation/seeding (A/I/S) section, a table, and the research nozzles. The rig will be unique in that it is designed to operate uncooled. The structure survives the 1960 R test condition because it uses carefully selected high temperature alloy materials such as Hastelloy-X. The lower plenum assembly was designed to operate at pressures to 450 psig at 1960 R, in accordance with the ASME B31.3 piping code. The natural gas-fueled combustor fires directly into the lower manifold. The hot air is directed through eight 1-1/2-in. supply pipes that supply the upper plenum. The flow is conditioned in the upper plenum prior to flowing to the research nozzle. The 1-1/2-in. supply lines are arranged in a U-shaped design to provide for a flexible piping system. The combustor assembly checkout was successfully conducted in Glenn's Engine Component Research Laboratory in the spring of 2001. The combustor is a low-smoke version of the J79 combustor used to power the F4 Phantom military aircraft. The natural gas-fueled combustor demonstrated high-efficiency combustion over a wide range of operating

  18. High readmission rate after heart valve surgery

    DEFF Research Database (Denmark)

    Sibilitz, K L; Berg, S K; Thygesen, Lau Caspar

    2015-01-01

    age (hazard ratio (95% CI): 1.3 (1.0-1.6)), male sex (1.2 (1.0-1.5)), mitral valve surgery (1.3 (1.0-1.6)), and infective endocarditis after surgery (1.8 (1.1-3.0), p: 0.01) predicted readmission, whereas higher age (2.3 (1.0-5.4)), higher comorbidity score (3.2 (1.8-6.0)), and infective endocarditis......BACKGROUND: After heart valve surgery, knowledge on long-term self-reported health status and readmission is lacking. Thus, the optimal strategy for out-patient management after surgery remains unclear. METHODS: Using a nationwide survey with linkage to Danish registers with one year follow-up, we...... included all adults 6-12 months after heart valve surgery irrespective of valve procedure, during Jan-June 2011 (n = 867). Participants completed a questionnaire regarding health-status (n = 742), and answers were compared with age- and sex-matched healthy controls. Readmission rates and mortality were...

  19. Scale dependence of the alignment between strain rate and rotation in turbulent shear flow

    Science.gov (United States)

    Fiscaletti, D.; Elsinga, G. E.; Attili, A.; Bisetti, F.; Buxton, O. R. H.

    2016-10-01

    The scale dependence of the statistical alignment tendencies of the eigenvectors of the strain-rate tensor ei, with the vorticity vector ω , is examined in the self-preserving region of a planar turbulent mixing layer. Data from a direct numerical simulation are filtered at various length scales and the probability density functions of the magnitude of the alignment cosines between the two unit vectors | ei.ω ̂| are examined. It is observed that the alignment tendencies are insensitive to the concurrent large-scale velocity fluctuations, but are quantitatively affected by the nature of the concurrent large-scale velocity-gradient fluctuations. It is confirmed that the small-scale (local) vorticity vector is preferentially aligned in parallel with the large-scale (background) extensive strain-rate eigenvector e1, in contrast to the global tendency for ω to be aligned in parallel with the intermediate strain-rate eigenvector [Hamlington et al., Phys. Fluids 20, 111703 (2008), 10.1063/1.3021055]. When only data from regions of the flow that exhibit strong swirling are included, the so-called high-enstrophy worms, the alignment tendencies are exaggerated with respect to the global picture. These findings support the notion that the production of enstrophy, responsible for a net cascade of turbulent kinetic energy from large scales to small scales, is driven by vorticity stretching due to the preferential parallel alignment between ω and nonlocal e1 and that the strongly swirling worms are kinematically significant to this process.

  20. On the use of in vivo measured flow rates as boundary conditions for image-based hemodynamic models of the human aorta: implications for indicators of abnormal flow.

    Science.gov (United States)

    Gallo, D; De Santis, G; Negri, F; Tresoldi, D; Ponzini, R; Massai, D; Deriu, M A; Segers, P; Verhegghe, B; Rizzo, G; Morbiducci, U

    2012-03-01

    The purpose of this study is to investigate how the imposition of personalized, non-invasively measured blood flow rates as boundary conditions (BCs) influences image-based computational hemodynamic studies in the human aorta. We extracted from 4D phase-contrast MRI acquisitions of a healthy human (1) the geometry of the thoracic aorta with supra-aortic arteries and (2) flow rate waveforms at all boundaries. Flow simulations were carried out, and the implications that the imposition of different BC schemes based on the measured flow rates have on wall shear stress (WSS)-based indicators of abnormal flow were analyzed. Our results show that both the flow rate repartition among the multiple outlets of the aorta and the distribution and magnitude of the WSS-based indicators are strongly influenced by the adopted BC strategy. Keeping as reference hemodynamic model the one where the applied BC scheme allowed to obtain a satisfactory agreement between the computed and the measured flow rate waveforms, differences in WSS-based indicators up to 49% were observed when the other BC strategies were applied. In conclusion, we demonstrate that in subject-specific computational hemodynamics models of the human aorta the imposition of BC settings based on non-invasively measured flow rate waveforms influences indicators of abnormal flow to a large extent. Hence, a BCs set-up assuring realistic, subject-specific instantaneous flow rate distribution must be applied when BCs such as flow rates are prescribed.

  1. A relationship between salivary flow rates and Candida counts in patients with xerostomia.

    Science.gov (United States)

    Nadig, Suchetha Devendrappa; Ashwathappa, Deepak Timmasandra; Manjunath, Muniraju; Krishna, Sowmya; Annaji, Araleri Gopalkrishna; Shivaprakash, Praveen Kunigal

    2017-01-01

    Most of the adult population is colonized by Candida in their oral cavity. The process of colonization depends on several factors, including the interaction between Candida and salivary proteins. Therefore, salivary gland hypofunction may alter the oral microbiota and increase the risk for opportunistic infections, such as candidiasis. Hence, it is necessary to evaluate the relationship between salivary flow rates (SFRs) and Candida colony counts in the saliva of patients with xerostomia. This study aims to determine and evaluate the relationship between SFRs and Candida colony forming units (CFUs) in patients with xerostomia. This study was a descriptive study. The study participants were taken from the patients attending outpatient department in a private dental college. Fifty patients, who reported xerostomia in a questionnaire of the symptoms of xerostomia, were selected. Chewing stimulated whole saliva samples were collected from them and their SFRs were assessed. Saliva samples were inoculated in the Sabouraud dextrose agar culture media for 24-48 h, and Candida CFUs were counted. Chi-squared test was used to analyze the data. There was a significant inverse relationship between salivary flow and candida CFUs count when patients with high colony counts were analyzed (cutoff point of 400 or greater CFU/mL). Females had less SFR than males. Most of the patients who had hyposalivation were taking medication for the underlying systemic diseases. Candida albicans was the most frequent species. There was a significantly negative correlation between SFRs and Candida CFUs in the patients with xerostomia.

  2. Do eosinophil counts correlate differently with asthma severity by symptoms versus peak flow rate?

    Science.gov (United States)

    Koshak, E A; Alamoudi, O S

    1999-12-01

    Discrepancy in asthmatic assessment by symptoms and peak flow rate (PFR) is a frequent dilemma. Currently, total peripheral eosinophil count (TPEC) is under study for asthma evaluation. To explore the correlation between TPEC and asthma severity assessed by symptoms alone versus symptoms and PFR. Adults asthmatics were selected from the Asthma Clinic. Severity assessment was based on two methods: symptoms alone or symptoms and PFR. Expiratory PFR was recorded by a Wright peak flow meter. Severity levels included mild intermittent, mild persistent, moderate persistent, and severe persistent. Total peripheral eosinophil count was performed on a Celldyn-3500 counter. Data was analyzed for statistical significance. Sixty asthmatics aged 15 to 70 years (mean = 34 years), of which 68.3% were female, were studied. Severity levels differed between the two assessment methods in 45% of the cases and showed a predominance of the moderate persistent type. Total peripheral eosinophil count ranged between 22 and 2470 cells/mm3 (mean = 520 +/- SD = 393) and eosinophilia was found in 50% of the cases. Total peripheral eosinophil count showed a high positive correlation with increased asthma severity level assessed by history alone (r = 0.460, P < .001); more than by history and PFR (r = 0.328, P < .05). The discrepancy between symptoms and PFR is confirmed by these results. A reliable objective parameter in asthma assessment is a continuous challenge. This study advocates the possible supplementation of TPEC as another objective parameter that might help in selecting the appropriate severity level in asthmatics.

  3. Exposure Time Distributions reveal Denitrification Rates along Groundwater Flow Path of an Agricultural Unconfined Aquifer

    Science.gov (United States)

    Kolbe, T.; Abbott, B. W.; Thomas, Z.; Labasque, T.; Aquilina, L.; Laverman, A.; Babey, T.; Marçais, J.; Fleckenstein, J. H.; Peiffer, S.; De Dreuzy, J. R.; Pinay, G.

    2016-12-01

    Groundwater contamination by nitrate is nearly ubiquitous in agricultural regions. Nitrate is highly mobile in groundwater and though it can be denitrified in the aquifer (reduced to inert N2 gas), this process requires the simultaneous occurrence of anoxia, an electron donor (e.g. organic carbon, pyrite), nitrate, and microorganisms capable of denitrification. In addition to this the ratio of the time groundwater spent in a denitrifying environment (exposure time) to the characteristic denitrification reaction time plays an important role, because denitrification can only occur if the exposure time is longer than the characteristic reaction time. Despite a long history of field studies and numerical models, it remains exceedingly difficult to measure or model exposure times in the subsurface at the catchment scale. To approach this problem, we developed a unified modelling approach combining measured environmental proxies with an exposure time based reactive transport model. We measured groundwater age, nitrogen and sulfur isotopes, and water chemistry from agricultural wells in an unconfined aquifer in Brittany, France, to quantify changes in nitrate concentration due to dilution and denitrification. Field data showed large differences in nitrate concentrations among wells, associated with differences in the exposure time distributions. By constraining a catchment-scale characteristic reaction time for denitrification with water chemistry proxies and exposure times, we were able to assess rates of denitrification along groundwater flow paths. This unified modeling approach is transferable to other catchments and could be further used to investigate how catchment structure and flow dynamics interact with biogeochemical processes such as denitrification.

  4. Deployable Emergency Shutoff Device Blocks High-Velocity Fluid Flows

    Science.gov (United States)

    Nabors, Sammy A.

    2015-01-01

    NASA's Marshall Space Flight Center has developed a device and method for blocking the flow of fluid from an open pipe. Motivated by the sea-bed oil-drilling catastrophe in the Gulf of Mexico in 2010, NASA innovators designed the device to plug, control, and meter the flow of gases and liquids. Anchored with friction fittings, spikes, or explosively activated fasteners, the device is well-suited for harsh environments and high fluid velocities and pressures. With the addition of instrumentation, it can also be used as a variable area flow metering valve that can be set based upon flow conditions. With robotic additions, this patent-pending innovation can be configured to crawl into a pipe then anchor and activate itself to block or control fluid flow.

  5. Effect of Various Sugary Beverages on Salivary pH, Flow Rate, and Oral Clearance Rate amongst Adults

    Directory of Open Access Journals (Sweden)

    Rinki Hans

    2016-01-01

    Full Text Available Introduction. Diet is a major aetiological factor for dental caries and enamel erosion. This study was undertaken with the aim of assessing the effect of selected locally available beverages on salivary pH, flow rate, and oral clearance rate amongst adults. Materials and Method. This clinical trial comprised 120 subjects. Test beverages undertaken were pepsi, fruit drink, coffee, and sweetened milk. Statistical analysis was carried out using SPSS version 17. Descriptive statistics, one-way ANOVA, and post hoc Tukey’s test were applied in the statistical tests. Results. It was found that salivary pH decreased for all the beverages immediately after consumption and the salivary flow rate increased after their consumption. The oral clearance rate of sweetened milk was found to be the least at 6.5 minutes and that of pepsi was found to be 13 minutes. However, the oral clearance rates of fruit drink and coffee were found to be equal at 15 minutes. Conclusion. Although it was found out that liquids cleared rapidly from the oral cavity, they had a significant cariogenic and erosive potential. Hence, it is always advised to minimise the consumption of beverages, especially amongst children and young adults to maintain a good oral health.

  6. Using acoustics to estimate inspiratory flow rate and drug removed from a dry powder inhaler.

    Science.gov (United States)

    Holmes, Martin S; Seheult, Jansen; Geraghty, Colm; D'Arcy, Shona; Costello, Richard W; Reilly, Richard B

    2013-01-01

    Morbidity and mortality rates of chronic respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD) are rising. There is a strong requirement for more effective management of these chronic diseases. Dry powder inhalers (DPIs) are one kind of devices currently employed to deliver medication aimed at controlling asthma and COPD symptoms. Despite their proven effectiveness when used correctly, some patients are unable to reach the inspiratory flow rate required to remove medication from the breath actuated devices and as a result, the medication does not reach the airways. This study employs an acoustic recording device, attached to a common DPI to record the audio signals of simulated inhalations. A rotameter was used to measure the flow rate through the inhaler while a milligram weighing scale was used to measure the amount of drug removed from each simulated inhalation. It was found that a strong correlation existed (R(2)>0.96) when average power, median amplitude, root mean square and mean absolute deviation were used to predict peak inspiratory flow rate. At a flow of 30 L/Min (mean absolute deviation=0.0049), it was found that 77% of the total emitted dose was removed from the inhaler. Results indicate that acoustic measurements may be used in the prediction of inspiratory flow rate and quantity of medication removed from an inhaler.

  7. Impact of physical incompatibility on drug mass flow rates: example of furosemide-midazolam incompatibility

    Science.gov (United States)

    2012-01-01

    Background Patients in intensive care units receive many drugs simultaneously but through limited venous accesses. Several intravenous therapies have to be administered through the same catheter, thus increasing the risk of physicochemical incompatibility. The purpose of this work was to assess and to quantify the impact of physical incompatibility on the mass flow rates of drugs infused simultaneously to the patient, through an in vitro study. Methods Furosemide-midazolam incompatibility was used to assess the impact of physical incompatibility on drug mass flow rates. Furosemide, midazolam, and saline were simultaneously infused. A filter was added at the end of the infusion line to retain visible particles. Two infusion conditions were tested with and without visible particles. A partial least square method on UV spectra was used to determine simultaneously the concentrations of the two drugs at the egress of the terminal extension line. The drug mass flow rate (expressed as mg/h) was calculated as the product of drug concentration versus total flow rate. Observed/theoretical mass flow rate ratios for each drug (%) were determined per infusion condition. Results Even in the absence of visible particles, precipitation of furosemide led to a drug loss estimated at between 10% and 15%. Furosemide is more impacted by interaction because the pH of the mixture is acid and this form is poorly soluble in an aqueous solution. Conclusions Physical incompatibility between furosemide and midazolam leads to a significant reduction in drug delivered to the patient and may result in treatment failure. PMID:22794308

  8. Influence Of Lixiviant Flow Rate On Heap Leaching Of Low Grade Manganese Carbonate Ore

    Science.gov (United States)

    Fobi, C. M.

    2008-12-01

    A study was carried out to ascertain the influence of lixiviant flow rate on leaching of low grade manganese carbonate ore from Nsuta, Ghana, and also the levels of impurities in the resulting leachate when the ore is heap-leached for 24 hours at two different flow rates. It was found out that the lixiviant flow rate has influence on the dissolution of manganese; about 8.42% recovery of manganese was obtained when the ore was leached at a flow rate of 5 ml/min whilst 99.28% was obtained in the case of 10 ml/min. It was also observed that some levels of impurities such as iron and magnesium were in the leachate: 4075 mg/l of iron and 2575 mg/l of magnesium were in the leachate when the ore was leached at a flow rate of 5 ml/min and 2500 mg/l of iron and 3970 mg/l of magnesium were in the leachate in the case of 10 ml/min. The results indicate that leachate should be purified before the final recovery of manganese from solution.

  9. ChargeOut! : discounted cash flow compared with traditional machine-rate analysis

    Science.gov (United States)

    Ted Bilek

    2008-01-01

    ChargeOut!, a discounted cash-flow methodology in spreadsheet format for analyzing machine costs, is compared with traditional machine-rate methodologies. Four machine-rate models are compared and a common data set representative of logging skidders’ costs is used to illustrate the differences between ChargeOut! and the machine-rate methods. The study found that the...

  10. Control of skin blood flow, sweating, and heart rate - Role of skin vs. core temperature

    Science.gov (United States)

    Wyss, C. R.; Brengelmann, G. L.; Johnson, J. M.; Rowell, L. B.; Niederberger, M.

    1974-01-01

    A study was conducted to generate quantitative expressions for the influence of core temperature, skin temperature, and the rate of change of skin temperature on sweat rate, skin blood flow, and heart rate. A second goal of the study was to determine whether the use of esophageal temperature rather than the right atrial temperature as a measure of core temperature would lead to different conclusions about the control of measured effector variables.

  11. Turbulent behaviour of non-cohesive sediment gravity flows at unexpectedly high flow density

    Science.gov (United States)

    Baker, Megan; Baas, Jaco H.; Malarkey, Jonathan; Kane, Ian

    2016-04-01

    Experimental lock exchange-type turbidity currents laden with non-cohesive silica-flour were found to be highly dynamic at remarkably high suspended sediment concentrations. These experiments were conducted to produce sediment gravity flows of volumetric concentrations ranging from 1% to 52%, to study how changes in suspended sediment concentration affects the head velocities and run-out distances of these flows, in natural seawater. Increasing the volumetric concentration of suspended silica-flour, C, up to C = 46%, within the flows led to a progressive increase in the maximum head velocity. This relationship suggests that suspended sediment concentration intensifies the density difference between the turbulent suspension and the ambient water, which drives the flow, even if almost half of the available space is occupied by sediment particles. However, from C = 46% to C = 52% a rapid reduction in the maximum head velocity was measured. It is inferred that at C = 46%, friction from grain-to-grain interactions begins to attenuate turbulence within the flows. At C > 46%, the frictional stresses become progressively more dominant over the turbulent forces and excess density, thus producing lower maximum head velocities. This grain interaction process started to rapidly reduce the run-out distance of the silica-flour flows at equally high concentrations of C ≥ 47%. All flows with C 9%. Yet, the critical flow concentration at which turbulence modulation commenced for these silica-flour laden flows appeared to be much higher. We suggest that Bagnold's 9% criterion cannot be applied to flows that carry fine-grained sediment, because turbulent forces are more important than dispersive forces, and frictional forces start to affect the flows only at concentrations just below the cubic packing density of spheres of C = 52%. These experimental results also imply that natural flows may be able to transport vast volumes of non-cohesive sediment with relative ease, especially

  12. Impact of syringe size on the performance of infusion pumps at low flow rates.

    Science.gov (United States)

    Schmidt, Nadia; Saez, Claudia; Seri, Istvan; Maturana, Andrés

    2010-03-01

    To evaluate the impact of syringe size on start-up delay and the time to reach 50% and 90% of target flow rates, using two commercially available syringe infusion pumps at infusion rates of < or =1 mL/hr. Two syringes (Terumo) of different size (10-mL and 50-mL), using two syringe infusion pumps (Pump A, Terumo Terufusion Infusion Pump TE-331; and Pump B, Braun Perfusor Compact S) were studied. Effective fluid delivery was measured at 0.4 mL/hr, 0.8 mL/hr, and 1.0 mL/hr for the initial 60 mins, using the gravimetric method. Instant flow was calculated as volume difference for every 1-min interval per minute. Start-up delay was defined as time in minutes of 0 flow from the start of infusion. Syringe placement, bubble removal, infusion line priming, and positioning were standardized for all measurements, using new syringes and infusion lines. Each experiment was repeated six times. Statistical analysis was performed, using a nonparametric test (Mann-Whitney U test). None. None. None. Using the 50-mL syringe, the start-up delay was consistently higher and the time to reach 50% and 90% of target flow were significantly longer, independent of which syringe infusion pump was used. At every flow rate studied, the pumps did not reach the target flow rate before 60 mins with the 50-mL syringe. With the 10-mL syringe, target flow rate was achieved before 20 mins for both pumps. Our findings demonstrate a clinically relevant impact of syringe size on syringe infusion pump performance at low flow rates. The time to reach 50% and 90% of target flow are significantly longer, using the 50-mL syringe compared with the 10-mL syringe, and the time to reach 50% of target flow is independent of the longer start-up delay. Based on our findings, we speculate that smaller syringe sizes and higher infusion rates are preferable for continuous drug infusions, particularly when prompt establishment of the drug effect is critical.

  13. Optimal power flow calculation for power system with UPFC considering load rate equalization

    Science.gov (United States)

    Liu, Jiankun; Chen, Jing; Zhang, Qingsong

    2017-06-01

    Unified power flow controller (UPFC) device can change system electrical quantity (such as voltage, impedance, phase angle, etc.) rapidly and flexibly under the premise of maintain security, stability and reliability of power system, thus can improve the transmission power and transmission line utilization, so as to enhance the power supply capacity of the power grid. Based on a thorough study of the steady-state model of UPFC, taking load rate equalization as objective function, the optimal power flow model is established with UPFC, and simplified interior point method is used to solve it. Finally, optimal power flow of 24 continuous sections actual data is calculated on a typical day of Nanjing network. The results show that the optimal power flow calculation with UPFC can optimize the load rate equalization on the basis of eliminating line overload, improving the voltage level of local power network.

  14. Studies with sample conductivity, insertion rates, and particle deflection in a continuous flow electrophoresis system

    Science.gov (United States)

    Williams, G., Jr.

    1982-01-01

    The continuous flow electrophoresis system makes electrophoresis possible in a free-flowing film of aqueous electrolyte medium. The sample continuously enters the electrolyte at the top of the chamber and is subjected to the action of a lateral dc field. This divides the sample into fractions since each component has a distinctive electrophoretic mobility. Tests were made using monodisperse polystyrene latex microspheres to determine optimum sample conductivity, insertion rates and optimum electric field applications as baseline data for future STS flight experiments. Optimum sample flow rates for the selected samples were determined to be approximately 26 micro-liters/min. Experiments with samples in deionized water yielded best results and voltages in the 20 V/cm to 30 V/cm range were optimum. Deflections of formaldehyde fixed turkey and bovine erythrocytes were determined using the continuous flow electrophoresis system. The effects of particle interactions on sample resolution and migration in the chamber was also evaluated.

  15. The influence of orifice height on flow rate of powder excipients.

    Science.gov (United States)

    Zatloukal, Z; Sklubalová, Z

    2011-12-01

    The influence of the orifice height of a cylindrical, flat-bottomed hopper on the mass flow rate of the free-flowable size fractions of sodium chloride and boric acid was investigated. It was observed that a zone of sudden acceleration of the mass flow under gravity occurred when a critical orifice height had been achieved. Based on the results, an orifice diameter equal to 12 mm with a height of between 8-16 mm is recommended for the faster flow of sodium chloride while an orifice diameter equal to 8 mm with a height of less than 8mm is appropriate for the slower flow of boric acid. In summary, the orifice height should be taken into consideration as an important parameter of a cylindrical test hopper in order to obtain a reproducible and comparable mass flow as the single-point characteristic of powder flowability.

  16. The Effect of Low Flow Inhalation Anesthesia on Operative Hemodynamic Condition in Comparison with High Flow Anesthesia

    Directory of Open Access Journals (Sweden)

    M Eidi

    2007-07-01

    Full Text Available Introduction & Objective: Low flow anesthesia technique in which the flow fresh gas is lower than minute volume of the patient results in improvement in the patient’s care such as reduction of operative hypothermia, reduction of postoperative shivering and leads to an increase in economical and enviornmental interests. The goal of the study was to investigate the patients’ operative hemodynamic variations using the high and low flow anesthesia techniques. Materials & Methods: This prospective, clincal and single blind study was carried out in Tbriz Emam Khomeini Hospital in 1384. In this study 97 patients in ASA class I or II after routine induction of G.A, during maintenance of anesthesia were randomly divided in two groups group I (high flow anesthesia and group II (low flow anesthesia. For all patients ECG, HR, SPO2, BP, B.T, ETCO2 and inspiratory, expiratory percentage of O2, N2O, halothane, postoprative shievring and duration of oprations were recorded. 46 patients underwent high flow anesthesia and 51 patients underwent low flow anesthesia. Results: The average blood pressure in group I was as follow: preoperative, systol=13820 mmHg and diastol=7815 mmHg, intraoperative, systol=10531 mmHg and diastol=6410 mmHg and in recovery systol=11615 mmHg and diastol=7013 mmHg. In group II who had low flow anesthesia the blood pressure was found to be systol=13922 mmHg and diastol=7922 mmHg preoperative, systol=12221 mmHg and diastol=7517 mmHg intraoperative and systol=11815 mmHg and diastol=7717 mmHg in recovery. The differences in blood pressure in both group were statiscally significant (p=0.01. The average heart rate in group I was 9018 beat/min preoperative, 7014 intraoperative and 126 in recovery. The avrage heart rate in group II was 87.921 preoperative, 8616 intraoperative and 10417 in recovery. The differences were statiscally significant but there was no significant difference between

  17. High data rate optical transceiver terminal

    Science.gov (United States)

    Clarke, E. S.

    1973-01-01

    The objectives of this study were: (1) to design a 400 Mbps optical transceiver terminal to operate from a high-altitude balloon-borne platform in order to permit the quantitative evaluation of a space-qualifiable optical communications system design, (2) to design an atmospheric propagation experiment to operate in conjunction with the terminal to measure the degrading effects of the atmosphere on the links, and (3) to design typical optical communications experiments for space-borne laboratories in the 1980-1990 time frame. As a result of the study, a transceiver package has been configured for demonstration flights during late 1974. The transceiver contains a 400 Mbps transmitter, a 400 Mbps receiver, and acquisition and tracking receivers. The transmitter is a Nd:YAG, 200 Mhz, mode-locked, CW, diode-pumped laser operating at 1.06 um requiring 50 mW for 6 db margin. It will be designed to implement Pulse Quaternary Modulation (PQM). The 400 Mbps receiver utilizes a Dynamic Crossed-Field Photomultiplier (DCFP) detector. The acquisition receiver is a Quadrant Photomultiplier Tube (QPMT) and receives a 400 Mbps signal chopped at 0.1 Mhz.

  18. Influence of biogas flow rate on biomass composition during the optimization of biogas upgrading in microalgal-bacterial processes.

    Science.gov (United States)

    Serejo, Mayara L; Posadas, Esther; Boncz, Marc A; Blanco, Saúl; García-Encina, Pedro; Muñoz, Raúl

    2015-03-03

    The influence of biogas flow rate (0, 0.3, 0.6, and 1.2 m(3) m(-2) h(-1)) on the elemental and macromolecular composition of the algal-bacterial biomass produced from biogas upgrading in a 180 L photobioreactor interconnected to a 2.5 L external bubbled absorption column was investigated using diluted anaerobically digested vinasse as cultivation medium. The influence of the external liquid recirculation/biogas ratio (0.5 biogas, was also evaluated. A L/G ratio of 10 was considered optimum to support CO2 and H2S removals of 80% and 100%, respectively, at all biogas flow rates tested. Biomass productivity increased at increasing biogas flow rate, with a maximum of 12 ± 1 g m(-2) d(-1) at 1.2 m(3) m(-2) h(-1), while the C, N, and P biomass content remained constant at 49 ± 2%, 9 ± 0%, and 1 ± 0%, respectively, over the 175 days of experimentation. The high carbohydrate contents (60-76%), inversely correlated to biogas flow rates, would allow the production of ≈100 L of ethanol per 1000 m(3) of biogas upgraded under a biorefinery process approach.

  19. Characteristics of combustion and heat transfer of excess enthalpy flames stabilized in a stagnation flow. 2nd Report. ; Heat flux at high flow rate and effects of Lewis number. Yodomi nagarechu ni anteika sareta choka enthalpy kaen no nensho oyobi etsudentatsu tokusei. 2. ; Koryuryo ni okeru netsuryusoku oyobi Lewis su no koka

    Energy Technology Data Exchange (ETDEWEB)

    Ito, S. (Daido Institute of Technology, Nagoya (Japan)); Asato, K.; Kawamura, T. (Gifu University, Gifu (Japan). Faculty of Engineerirng); Mazaki, T. (Daido Senior High School, Nagoya (Japan)); Umemura, H. (Mitsubishi Electric Corp., Tokyo (Japan))

    1993-08-25

    For the purpose of developing small-sized combustors of high heat transfer efficiency for household and business uses, a study has been carried out on the characteristics of an excess enthalpy flame stabilized in a stagnant flow, the maximum heat flux utilizable from flames through a heat receiver wall, the heat transfer characteristics near the extinction limits, and the effects of Lewis number (Le). Even when heat is drawn from the heat receiver wall in the downstream of flames, stable flames are kept until they extremely approach the heat receiver wall by the effect of preheating for lean methane-air flames of Le[approx equal]1.0 and lean propane-air flames of Le>1.0 and by the effect of preheating and Lewis effect for lean hydrogen-air flames of Le<1.0. In any flames, therefore, the heat flux to the heat receiver wall increases abruptly with the increase of stagnant velocity gradient and thereby the heat transfer characteristics at the heat receiver wall are improved. Heat transfer in the cases where flames exist on the outside and inside of the temperature boundary layer depend not on the thickness of the temperature boundary layer but on the position of flames. 6 refs., 9 figs.

  20. The effect of chewing gum's flavor on salivary flow rate and pH

    OpenAIRE

    Karami-Nogourani, Maryam; Kowsari-Isfahan, Raha; Hosseini-Beheshti, Mozhgan

    2011-01-01

    Background: Chewing sugar-free gums is a convenient way to increase salivary flow. Salivary flow increases in response to both gustatory (taste) and mechanical (chewing) stimuli, and chewing gum can provide both of these stimuli. The aim of this study was to compare the effect of five different flavors of sugar-free chewing gum on the salivary flow rate (SFR) and pH. Materials and Methods: Fifteen dental students volunteered at the same time on six consecutive days, to collect one minute u...

  1. The relationship between drained angle and flow rate of size fractions of powder excipients.

    Science.gov (United States)

    Sklubalová, Z; Zatloukal, Z

    2009-12-01

    The influence of powder size of chosen pharmaceutical powder excipients on drained angle as well as the correlation between drained angle and the mass flow rate of certain powder size fractions were investigated in this work. A method of the indirect estimation of the three-dimensional drained angle from the mass of the residual powder was used experimentally to study the influence of powder size fractions in range of 0.200-0.630 mm for sodium chloride, sodium citrate, potassium chloride, and potassium citrate. Failures of flow significantly increased the drained angles for powder size fraction of 0.200-0.250 mm. For the uniformly flowable powder size fraction of 0.400-0.500 mm, the faster the flow rate, the smaller drained angles were observed for excipients investigated. To estimate parameters of the flow equation, the measurement of material flow rates from the hopper of different orifice sizes is needed, while the estimation of drained angle is much easier needing only one hopper. Finally, the increase of the hopper wall angle of the standard conical hopper to 70 degrees could be recommended to achieve uniform mass flow and to reduce the adverse effect of powder gliding along the hopper walls.

  2. An adaptive finite element method for high speed flows

    Science.gov (United States)

    Peraire, J.; Morgan, K.; Peiro, J.; Zienkiewicz, O. C.

    1987-01-01

    The solution of the equations of compressible high speed flow, on unstructured triangular grids in 2D and tetrahedral grids in 3D, is considered. Solution methods based upon both Taylor-Galerkin and Runge-Kutta time-stepping techniques are presented and the incorporation of the ideas of flux corrected transport (FCT) is discussed. These methods are combined with an adaptive mesh regeneration procedure and are employed in the solution of several examples, consisting of Euler flows in both 2D and 3D and Navier-Stokes flows in 2D.

  3. Salivary flow rates among women diagnosed with benign and malignant tumors.

    Science.gov (United States)

    Napeñas, Joel J; Miles, Leslie; Guajardo-Streckfus, Cynthia; Streckfus, Charles F

    2013-01-01

    The purpose of this study was to compare salivary flow rates (SWS) among patients diagnosed with benign and varying malignant solid tumors with the comparison group, prior to the initiation of any treatment. An evaluation of the results found that mean baseline SWS flow rates were higher for healthy patients (1.55 ml/min) when compared to patients diagnosed with benign tumors (1.13 ml/min), breast cancer (1.09 ml/min), and reproductive carcinomas (0.94 ml/min). The overall model (F = 7.76; p flow rates. The results suggest that salivary secretion is lower among both benign and malignant tumor subjects prior to the initiation of treatment. Salivary evaluations of subjects prior to treatment may be useful in identifying individuals at risk for oral complications during chemotherapy. ©2013 Special Care Dentistry Association and Wiley Periodicals, Inc.

  4. Primary standards for measuring flow rates from 100 nl/min to 1 ml/min - gravimetric principle.

    Science.gov (United States)

    Bissig, Hugo; Petter, Harm Tido; Lucas, Peter; Batista, Elsa; Filipe, Eduarda; Almeida, Nelson; Ribeiro, Luis Filipe; Gala, João; Martins, Rui; Savanier, Benoit; Ogheard, Florestan; Niemann, Anders Koustrup; Lötters, Joost; Sparreboom, Wouter

    2015-08-01

    Microflow and nanoflow rate calibrations are important in several applications such as liquid chromatography, (scaled-down) process technology, and special health-care applications. However, traceability in the microflow and nanoflow range does not go below 16 μl/min in Europe. Furthermore, the European metrology organization EURAMET did not yet validate this traceability by means of an intercomparison between different National Metrology Institutes (NMIs). The NMIs METAS, Centre Technique des Industries Aérauliques et Thermiques, IPQ, Danish Technological Institute, and VSL have therefore developed and validated primary standards to cover the flow rate range from 0.1 μl/min to at least 1 ml/min. In this article, we describe the different designs and methods of the primary standards of the gravimetric principle and the results obtained at the intercomparison for the upper flow rate range for the various NMIs and Bronkhorst High-Tech, the manufacturer of the transfer standards used.

  5. The Effect of Minimum Wage Rates on High School Completion

    Science.gov (United States)

    Warren, John Robert; Hamrock, Caitlin

    2010-01-01

    Does increasing the minimum wage reduce the high school completion rate? Previous research has suffered from (1. narrow time horizons, (2. potentially inadequate measures of states' high school completion rates, and (3. potentially inadequate measures of minimum wage rates. Overcoming each of these limitations, we analyze the impact of changes in…

  6. Retrograde flow and shear rate acutely impair endothelial function in humans.

    Science.gov (United States)

    Thijssen, Dick H J; Dawson, Ellen A; Tinken, Toni M; Cable, N Timothy; Green, Daniel J

    2009-06-01

    Changes in arterial shear stress induce functional and structural vasculature adaptations. Recent studies indicate that substantial retrograde flow and shear can occur through human conduit arteries. In animals, retrograde shear is associated with atherogenic effects. The aim of this study was to examine the impact of incremental levels of retrograde shear on endothelial function in vivo. On 3 separate days, we examined bilateral brachial artery flow-mediated dilation, an index of NO-mediated endothelial function, in healthy men (24+/-3 years) before and after a 30-minute intervention consisting of cuff inflation to 25, 50, or 75 mm Hg. Cuff inflations resulted in "dose"-dependent increases in retrograde shear rate, compared with the noncuffed arm, within subjects (P<0.001). Flow-mediated dilation in the cuffed arm did not change in response to the 25-mm Hg stimulus but decreased significantly after both the 50- and 75-mm Hg interventions (P<0.05). The decrease in flow-mediated dilation after the 75-mm Hg intervention was significantly larger than that observed after a 50-mm Hg intervention (P=0.03). In the noncuffed arm, no changes in shear rate or flow-mediated dilation were observed. These results demonstrate that an increase in retrograde shear rate induces a dose-dependent attenuation of endothelial function in humans. This finding contributes to our understanding regarding the possible detrimental effects of retrograde shear rate in vivo.

  7. Estimation of Leak Flow Rate during Post-LOCA Using Cascaded Fuzzy Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Yeong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Na, Man Gyun [Chosun University, Gwangju (Korea, Republic of)

    2016-10-15

    In this study, important parameters such as the break position, size, and leak flow rate of loss of coolant accidents (LOCAs), provide operators with essential information for recovering the cooling capability of the nuclear reactor core, for preventing the reactor core from melting down, and for managing severe accidents effectively. Leak flow rate should consist of break size, differential pressure, temperature, and so on (where differential pressure means difference between internal and external reactor vessel pressure). The leak flow rate is strongly dependent on the break size and the differential pressure, but the break size is not measured and the integrity of pressure sensors is not assured in severe circumstances. In this paper, a cascaded fuzzy neural network (CFNN) model is appropriately proposed to estimate the leak flow rate out of break, which has a direct impact on the important times (time approaching the core exit temperature that exceeds 1200 .deg. F, core uncover time, reactor vessel failure time, etc.). The CFNN is a data-based model, it requires data to develop and verify itself. Because few actual severe accident data exist, it is essential to obtain the data required in the proposed model using numerical simulations. In this study, a CFNN model was developed to predict the leak flow rate before proceeding to severe LOCAs. The simulations showed that the developed CFNN model accurately predicted the leak flow rate with less error than 0.5%. The CFNN model is much better than FNN model under the same conditions, such as the same fuzzy rules. At the result of comparison, the RMS errors of the CFNN model were reduced by approximately 82 ~ 97% of those of the FNN model.

  8. Comparison of Gravity Flow Rates Between ENFit and Legacy Feeding Tubes.

    Science.gov (United States)

    Mundi, Manpreet S; Duellman, Wanda; Epp, Lisa; Davidson, Jacob; Hurt, Ryan T

    2017-04-01

    Misconnections between enteral supplies and other access devices have led to significant morbidity and mortality. To reduce misconnections, a standard small-bore connector has been developed (International Organization for Standards 80369-8; ENFit). The full impact of transition to this connector is not known, however. Working with major manufacturers and Food and Drug Administration, we obtained ENFit and comparative legacy tubes of variable sizes (low-profile, 14F, 18F, 20F, and 24F balloon gastrostomies). Gravity enteral feeding was simulated with an empty bolus syringe attached to the feeding tube to be tested. The tube was clamped and filled to the 60-mL mark with liquid (water, Jevity 1 Cal, Isosource HN, Isosource 1.5 Cal, Two Cal HN, and Nourish). The clamp was released, and time for formula to leave the syringe was recorded. There was no difference in flow rate between the aggregate legacy and ENFit tubes for the low-profile, 18F, and 20F sizes. The ENFit 14F tubes had a lower flow rate versus the legacy tubes, largely due to the low flow rates seen with the 1 ENFit tube. Similarly, 24F ENFit tubes with some formulas yielded lower flow rates as opposed to legacy. Overall, for the low-profile, 18F, and 20F sizes, the ENFit tubes had similar flow rates when compared with the legacy tubes. For the 14F and 24F sizes, the flow rate of ENFit tubes was significantly lower, which could result in longer EN delivery for patients who are using these tubes to provide gravity feeding.

  9. Co-relationships between glandular salivary flow rates and dental caries.

    Science.gov (United States)

    Diaz de Guillory, Carolina; Schoolfield, John D; Johnson, Dorthea; Yeh, Chih-Ko; Chen, Shuo; Cappelli, David P; Bober-Moken, Irene G; Dang, Howard

    2014-09-01

    This study was designed to evaluate the relationship of age, gender, ethnicity and salivary flow rates on dental caries in an adult population using data collected from the Oral Health San Antonio Longitudinal Study of Aging (OH: SALSA). Saliva is essential to maintain a healthy oral environment and diminished output can result in dental caries. Although gender and age play a role in the quantity of saliva, little is known about the interaction of age, gender and ethnicity on dental caries and salivary flow rates. Data from the 1147 participants in the OH: SALSA were analysed. The dependent variables were the number of teeth with untreated coronal caries, number of teeth with root caries and the number of coronal and root surfaces with untreated caries. The independent variables were stimulated and unstimulated glandular salivary flow rates along with the age, sex and ethnicity (e.g. European or Mexican ancestry) of the participants. Coronal caries experience was greater in younger participants while root surface caries experience was greater in the older participants. Coronal caries was lower in the older age groups while the root caries experience increased. Men had a statistically significant (p flow rates showed no age difference and remained constant with age, whereas the age differences in the unstimulated and stimulated submandibular/sublingual salivary flow rates were significant. The mean number of teeth with coronal and root caries was higher in Mexican-Americans than in European-Americans. Over one-fourth of the adults between the ages of 60 and 79 have untreated root caries over one-third having untreated coronal caries. Lower salivary flow rates play a significant role in both the number of teeth and the number of surfaces developing caries in these adults. Women and individuals of European-American ancestry experience less caries. © 2013 The Gerodontology Society and John Wiley & Sons A/S.

  10. Validating Whole-Airway CFD Predictions of DPI Aerosol Deposition at Multiple Flow Rates.

    Science.gov (United States)

    Longest, P Worth; Tian, Geng; Khajeh-Hosseini-Dalasm, Navvab; Hindle, Michael

    2016-12-01

    The objective of this study was to compare aerosol deposition predictions of a new whole-airway CFD model with available in vivo data for a dry powder inhaler (DPI) considered across multiple inhalation waveforms, which affect both the particle size distribution (PSD) and particle deposition. The Novolizer DPI with a budesonide formulation was selected based on the availability of 2D gamma scintigraphy data in humans for three different well-defined inhalation waveforms. Initial in vitro cascade impaction experiments were conducted at multiple constant (square-wave) particle sizing flow rates to characterize PSDs. The whole-airway CFD modeling approach implemented the experimentally determined PSDs at the point of aerosol formation in the inhaler. Complete characteristic airway geometries for an adult were evaluated through the lobar bronchi, followed by stochastic individual pathway (SIP) approximations through the tracheobronchial region and new acinar moving wall models of the alveolar region. It was determined that the PSD used for each inhalation waveform should be based on a constant particle sizing flow rate equal to the average of the inhalation waveform's peak inspiratory flow rate (PIFR) and mean flow rate [i.e., AVG(PIFR, Mean)]. Using this technique, agreement with the in vivo data was acceptable with <15% relative differences averaged across the three regions considered for all inhalation waveforms. Defining a peripheral to central deposition ratio (P/C) based on alveolar and tracheobronchial compartments, respectively, large flow-rate-dependent differences were observed, which were not evident in the original 2D in vivo data. The agreement between the CFD predictions and in vivo data was dependent on accurate initial estimates of the PSD, emphasizing the need for a combination in vitro-in silico approach. Furthermore, use of the AVG(PIFR, Mean) value was identified as a potentially useful method for characterizing a DPI aerosol at a constant flow rate.

  11. High bias gas flows increase lung injury in the ventilated preterm lamb.

    Directory of Open Access Journals (Sweden)

    Katinka P Bach

    Full Text Available BACKGROUND: Mechanical ventilation of preterm babies increases survival but can also cause ventilator-induced lung injury (VILI, leading to the development of bronchopulmonary dysplasia (BPD. It is not known whether shear stress injury from gases flowing into the preterm lung during ventilation contributes to VILI. METHODS: Preterm lambs of 131 days' gestation (term = 147 d were ventilated for 2 hours with a bias gas flow of 8 L/min (n = 13, 18 L/min (n = 12 or 28 L/min (n = 14. Physiological parameters were measured continuously and lung injury was assessed by measuring mRNA expression of early injury response genes and by histological analysis. Control lung tissue was collected from unventilated age-matched fetuses. Data were analysed by ANOVA with a Tukey post-hoc test when appropriate. RESULTS: High bias gas flows resulted in higher ventilator pressures, shorter inflation times and decreased ventilator efficiency. The rate of rise of inspiratory gas flow was greatest, and pulmonary mRNA levels of the injury markers, EGR1 and CTGF, were highest in lambs ventilated with bias gas flows of 18 L/min. High bias gas flows resulted in increased cellular proliferation and abnormal deposition of elastin, collagen and myofibroblasts in the lung. CONCLUSIONS: High ventilator bias gas flows resulted in increased lung injury, with up-regulation of acute early response genes and increased histological lung injury. Bias gas flows may, therefore, contribute to VILI and BPD.

  12. High regression rate, high density hybrid fuels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR program will investigate high energy density novel nanofuels combined with high density binders for use with an N2O oxidizer. Terves has developed...

  13. Effects of Chewing Different Flavored Gums on Salivary Flow Rate and pH

    OpenAIRE

    Karami Nogourani, Maryam; Janghorbani, Mohsen; Kowsari Isfahan, Raha; Hosseini Beheshti, Mozhgan

    2012-01-01

    Chewing gum increases salivary flow rate (SFR) and pH, but differences in preferences of gum flavor may influence SFR and pH. The aim of this paper was to assess the effect of five different flavors of sucrose-free chewing gum on the salivary flow rate and pH in healthy dental students in Isfahan, Iran. Fifteen (7 men and 8 women) healthy dental student volunteers collected unstimulated saliva and then chewed one of five flavored gums for 6 min. The whole saliva was collected and assessed for...

  14. The rate dependence of the saturation flow stress of Cu and 1100 Al

    Energy Technology Data Exchange (ETDEWEB)

    Preston, D.L.; Tonks, D.L.; Wallace, D.C.

    1991-01-01

    The strain-rate dependence of the saturation flow stress of OFHC Cu and 1100 Al from 10{sup {minus}3}s{sup {minus}1} to nearly to 10{sup 12}s{sup {minus}1} is examined. The flow stress above 10{sup 9}s{sup {minus}1} is estimated using Wallace's theory of overdriven shocks in metals. A transition to the power-law behavior {Psi} {approximately} {tau}{sub s}{sup 5} occurs at a strain rate of order 10{sup 5}s{sup {minus}1}. 10 refs., 2 figs.

  15. Effects of neuropeptide Y on regulation of blood flow rate in canine myocardium

    DEFF Research Database (Denmark)

    Svendsen, J H; Sheikh, S P; Jørgensen, J

    1990-01-01

    The effect of neuropeptide Y (NPY) on tension development was examined in isolated canine coronary arteries, and the effects on local myocardial blood flow rate were studied in open-chest anesthetized dogs by the local 133Xe washout technique. By immunohistochemistry, numerous NPY-like immunoreac......The effect of neuropeptide Y (NPY) on tension development was examined in isolated canine coronary arteries, and the effects on local myocardial blood flow rate were studied in open-chest anesthetized dogs by the local 133Xe washout technique. By immunohistochemistry, numerous NPY...

  16. Peak expiratory flow rates produced with the Laerdal and Mapleson-C bagging circuits.

    Science.gov (United States)

    Jones, A; Hutchinson, R; Lin, E; Oh, T

    1992-01-01

    This study compared the peak expiratory flow rates (PEFR) at different inspiratory pause pressures (IPP) produced by the Mapleson-C circuit and the Laerdal self-inflating resuscitator. The difference in PEFR produced by the two circuits was significantly different at the lowest and the highest IPP studied (I3 and 38cm H20). The greatest differences in the mean expiratory flow rates produced was, however, only 0.07 litre sec(-7). The authors suggest that the choice of bagging circuit should depend on the experience and familiarity of the therapist with the circuit. Copyright © 1992 Australian Physiotherapy Association. Published by . All rights reserved.

  17. The Steady Flow Resistance of Perforated Sheet Materials in High Speed Grazing Flows

    Science.gov (United States)

    Syed, Asif A.; Yu, Jia; Kwan, H. W.; Chien, E.; Jones, Michael G. (Technical Monitor)

    2002-01-01

    A study was conducted to determine the effects of high speed grazing air flow on the acoustic resistance of perforated sheet materials used in the construction of acoustically absorptive liners placed in commercial aircraft engine nacelles. Since DC flow resistance of porous sheet materials is known to be a major component of the acoustic resistance of sound suppression liners, the DC flow resistance of a set of perforated face-sheets and linear 'wiremesh' face-sheets was measured in a flow duct apparatus (up to Mach 0.8). Samples were fabricated to cover typical variations in perforated face-sheet parameters, such as hole diameter, porosity and sheet thickness, as well as those due to different manufacturing processes. The DC flow resistance data from perforated sheets were found to correlate strongly with the grazing flow Mach number and the face-sheet porosity. The data also show correlation against the boundary layer displacement thickness to hole-diameter ratio. The increase in resistance with grazing flow for punched aluminum sheets is in good agreement with published results up to Mach 0.4, but is significantly larger than expected above Mach 0.4. Finally, the tests demonstrated that there is a significant increase in the resistance of linear 'wiremesh' type face-sheet materials.

  18. Robust and Optimal Control of Magnetic Microparticles inside Fluidic Channels with Time-Varying Flow Rates

    Directory of Open Access Journals (Sweden)

    Islam S.M. Khalil

    2016-06-01

    Full Text Available Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For example, magnetic particles need to be navigated controllably in vessels against flowing streams of body fluid. This paper describes the motion control of paramagnetic microparticles in the flowing streams of fluidic channels with time-varying flow rates (maximum flow is 35 ml.hr−1. This control is designed using a magnetic-based proportional-derivative (PD control system to compensate for the time-varying flow inside the channels (with width and depth of 2 mm and 1.5 mm, respectively. First, we achieve point-to-point motion control against and along flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1. The average speeds of single microparticle (with average diameter of 100 μm against flow rates of 6 ml.hr−1 and 30 ml.hr−1 are calculated to be 45 μm.s−1 and 15 μm.s−1, respectively. Second, we implement PD control with disturbance estimation and compensation. This control decreases the steady-state error by 50%, 70%, 73%, and 78% at flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1, respectively. Finally, we consider the problem of finding the optimal path (minimal kinetic energy between two points using calculus of variation, against the mentioned flow rates. Not only do we find that an optimal path between two collinear points with the direction of maximum flow (middle of the fluidic channel decreases the rise time of the microparticles, but we also decrease the input current that is supplied to the electromagnetic coils by minimizing the kinetic energy of the microparticles, compared to a PD control with disturbance compensation.

  19. Meta-Analysis of Salivary Flow Rates in Young and Older Adults.

    Science.gov (United States)

    Affoo, Rebecca H; Foley, Norine; Garrick, Rushlee; Siqueira, Walter L; Martin, Ruth E

    2015-10-01

    To determine whether salivary flow decreases as a function of aging. Meta-analysis. Literature review. Individuals aged 18 and older reported to be free of major systemic disease. Relevant studies were identified through a literature search of several databases, from their inception to June 2013. Studies were included if saliva had been collected on at least one occasion in subjects aged 18 and older and if the data were presented in a manner that enabled comparisons of younger and older participants. Differences in salivary flow rates between age groups were calculated for each salivary source and condition and reported as standardized mean differences (SMDs), standard errors (SEs) and 95% confidence intervals (CIs). The results were pooled using a random effects model. A separate analysis examining medication use was also conducted. Forty-seven studies were included. Whole (SMD = 0.551, SE = 0.056, 95% CI = 0.423-0.678, P flow rates were reduced significantly in older participants and in unstimulated and stimulated conditions. In contrast, parotid and minor gland salivary flow rates were not significantly reduced with increasing age. Additionally, unstimulated and stimulated SMSL, and unstimulated whole salivary flow rates were significantly lower in older adults, regardless of medication usage. The aging process is associated with reduced salivary flow in a salivary-gland-specific manner; this reduction in salivary flow cannot be explained on the basis of medications. These findings have important clinical implications for maintaining optimal oral health in older adults. © 2015, Copyright the Authors Journal compilation © 2015, The American Geriatrics Society.

  20. An investigation of the effect of pore scale flow on average geochemical reaction rates using direct numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Molins, Sergi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division; Trebotich, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Computational Research Division; Steefel, Carl I. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division; Shen, Chaopeng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Computational Research Division

    2012-03-30

    The scale-dependence of geochemical reaction rates hinders their use in continuum scale models intended for the interpretation and prediction of chemical fate and transport in subsurface environments such as those considered for geologic sequestration of CO2. Processes that take place at the pore scale, especially those involving mass transport limitations to reactive surfaces, may contribute to the discrepancy commonly observed between laboratory-determined and continuum-scale or field rates. In this study we investigate the dependence of mineral dissolution rates on the pore structure of the porous media by means of pore scale modeling of flow and multicomponent reactive transport. The pore scale model is composed of high-performance simulation tools and algorithms for incompressible flow and conservative transport combined with a general-purpose multicomponent geochemical reaction code. The model performs direct numerical simulation of reactive transport based on an operator-splitting approach to coupling transport and reactions. The approach is validated with a Poiseuille flow single-pore experiment and verified with an equivalent 1-D continuum-scale model of a capillary tube packed with calcite spheres. Using the case of calcite dissolution as an example, the high-resolution model is used to demonstrate that nonuniformity in the flow field at the pore scale has the effect of decreasing the overall reactivity of the system, even when systems with identical reactive surface area are considered. In conclusion, the effect becomes more pronounced as the heterogeneity of the reactive grain packing increases, particularly where the flow slows sufficiently such that the solution approaches equilibrium locally and the average rate becomes transport-limited.

  1. A non-contact optical procedure for precise measurement of respiration rate and flow

    Science.gov (United States)

    Scalise, Lorenzo; Marchionni, Paolo; Ercoli, Ilaria

    2010-04-01

    The use of standard instrumentation for the assessment of the respiration rate as of flow is an important goal in medicine. Spirometers, textile-based capacitive sensors or photopletismography are standard contact instrumentations used for such aim; the main drawback in the use of such instrumentations is the necessity to have a direct contact of the instrument with the patient. In this paper, we present an optical no-contact method for monitoring of both the respiration rate and flow. This method is based on the measurement of external chest wall movement by a laser Doppler vibrometer. The measurement procedure has already been demonstrated to be extremely well performing for what concern the monitoring of the cardiac activity. The proposed method can be operated at a distance of 1.5 m, on different point of the patient thoracic and abdominal area. We have monitored respiration rate and flow on 8 patients with a spirometer and simultaneously with the proposed noncontact measurement procedure. Bland-Altman analysis of the respiration rate measured with both instruments demonstrate a mean error on the determination of the respiration rate of < 1% and of the < 4% for the instantaneous flow. We also report a study on the optimal position on the thoracic area based on quality of the signal measured on the same population of subject.

  2. Channel Geometry and Flood Flows: Quantifying over-bank flow dynamics during high-flow events in North Carolina's floodplains

    Science.gov (United States)

    Lovette, J. P.; Duncan, J. M.; Vimal, S.; Band, L. E.

    2015-12-01

    Natural riparian areas play numerous roles in the maintenance and improvement of stream water quality. Both restoration of riparian areas and improvement of hydrologic connectivity to the stream are often key goals of river restoration projects. These management actions are designed to improve nutrient removal by slowing and treating overland flow delivered from uplands and by storing, treating, and slowly releasing streamwater from overbank inundation during flood events. A major question is how effective this storage of overbank flow is at treating streamwater based on the cumulative time stream discharge at a downstream location has spent in shallower, slower overbank flow. The North Carolina Floodplain Mapping Program maintains a detailed statewide Flood Risk Information System (FRIS) using HEC-RAS modeling, lidar, and detailed surveyed river cross-sections. FRIS provides extensive information regarding channel geometry on approximately 39,000 stream reaches (a slightly coarser spatial resolution than the NHD+v2 dataset) with tens of cross-sections for each reach. We use this FRIS data to calculate volume and discharge from floodplain riparian areas separately from in-channel flow during overbank events. Preliminary results suggest that a small percentage of total annual discharge interacts with the full floodplain extent along a stream reach due to the infrequency of overbank flow events. However, with the significantly different physical characteristics of the riparian area when compared to the channel itself, this overbank flow can provide unique services to water quality. Our project aims to use this information in conjunction with data from the USGS SPARROW program to target non-point source hotspots of Nitrogen and Phosphorus addition and removal. By better understanding the flow dynamics within riparian areas during high flow events, riparian restoration projects can be carried out with improved efficacy.

  3. Applications of an adaptive unstructured solution algorithm to the analysis of high speed flows

    Science.gov (United States)

    Thareja, R. R.; Prabhu, R. K.; Morgan, K.; Peraire, J.; Peiro, J.

    1990-01-01

    An upwind cell-centered scheme for the solution of steady laminar viscous high-speed flows is implemented on unstructured two-dimensional meshes. The first-order implementation employs Roe's (1981) approximate Riemann solver, and a higher-order extension is produced by using linear reconstruction with limiting. The procedure is applied to the solution of inviscid subsonic flow over an airfoil, inviscid supersonic flow past a cylinder, and viscous hypersonic flow past a double ellipse. A detailed study is then made of a hypersonic laminar viscous flow on a 24-deg compression corner. It is shown that good agreement is achieved with previous predictions using finite-difference and finite-volume schemes. However, these predictions do not agree with experimental observations. With refinement of the structured grid at the leading edge, good agreement with experimental observations for the distributions of wall pressure, heating rate and skin friction is obtained.

  4. High-resolution AUV mapping and lava flow ages at Axial Seamount

    Science.gov (United States)

    Clague, D. A.; Paduan, J. B.; Dreyer, B. M.; Caress, D. W.; Martin, J.

    2011-12-01

    Mapping along mid-ocean ridges, as on land, requires identification of flow boundaries and sequence, and ages of some flows to understand eruption history. Multibeam sonars on autonomous underwater vehicles (AUV) now generate 1-m resolution maps that resolve lava pillars, internal flow structures and boundaries, and lava flow emplacement sequences using crosscutting relations and abundance of fissures. MBARI has now mapped the summit caldera floor and rims and the upper south rift zone on Axial Seamount on the Juan de Fuca Ridge. With the advent of the high-resolution bathymetry and the ability to observe flow contacts to determine superposition using ROVs and submersibles, the missing component has been determining absolute ages of the flows. We used the MBARI ROV Doc Ricketts to collect short push cores (Six ages from the lowermost part of the south rift of Axial Seamount include samples on a cone with deep summit crater that is ~16,580 aBP and on 5 flows between 950 and 1510 aBP. Two additional flows from the southeast rim of the caldera are 905 and 2005 aBP. An age of 6910 aBP from 15 cm depth in a 2-m volcaniclastic unit on top of a pre-caldera flow on the eastern rim of the caldera suggests formation of the caldera several tens of thousands aBP. Seven ages on at least 5 flows on the floor of Axial caldera range from 620 to 1145 aBP, whereas 10 extensive mapped flows are all inferred to be <620 aBP as they are covered by sediment too thin to sample. The older pillow flows are difficult to map as discrete flows. In contrast, the 11 flows erupted during the last 620 years have an eruption frequency of 55 years. Of these, 6 not significantly overlapped by younger flows have a combined surface area of 30.2 km2 and represent roughly the output over 275 years of eruptive activity in the caldera at Axial Seamount, although they were not erupted in a continuous 275 year timespan. If we use average flow thicknesses of 3-5 m for these sheet flows, we estimate a lava

  5. The Effect of Insulating Blood Warmer Output Tubing on the Temperature of Packed Red Blood Cells at Low Flow Rates

    Science.gov (United States)

    1989-01-01

    blood cells at the point of patient entry at low flow rates . Utilizing a surgical suite, every attempt was made to replicate a true surgical setting...Flow control pumps were used to regulate flow rates of 300, 600, and 900 milliliters per hour (ml/hr) through Fenwall Laboratories blood warming coils

  6. High Definition Graphics Application In Fluid Flow Simulations

    Science.gov (United States)

    Bancroft, Gordon; Merritt, Fergus; Buning, Pieter; Watson, Val

    1987-06-01

    The Fluid Dynamics Division of the NASA Ames Research Center is using high definition (high spatial and color resolution) computer graphics to help visualize flow fields from computer simulations of air flow about vehicles such as the Space Shuttle. Computational solutions of the flow field are obtained from Cray supercomputers. These solutions are then transferred to Silicon Graphics Workstations for creation and interactive viewing of dynamic 3D displays of the flow fields. The scientist's viewing position in the 3D space can be interactively changed while the fluid flow is either frozen in time or moving in time. Specific animated sequences can be created for viewing on the workstation or for recording on video tape or 16mm movies with the aid of specialized software that permits easy editing and automatic "tweening" of the sequences. This paper will describe the software developed for creating the 3D flow field displays and for creating the animation sequences. It will also specify the hardware required to generate these displays, to record them on video tape, and to record them on 16mm film. A video tape will be shown to illustrate the capabilities of the hardware and software with examples.

  7. Quasi-three dimensional hydraulic design and performance calculation of high specific speed mixed-flow pump

    Science.gov (United States)

    Su, M.; Zhang, Y. X.; Zhang, J. Y.; Hou, H. C.

    2016-05-01

    According to the basic parameters of 211-80 high specific speed mixed-flow pump, based on the quasi-three dimensional flow theory, the hydraulic design of impeller and its matching spaced guide vanes for high specific speed mixed flow pump was completed, in which the iterative calculation of S 1, S 2 stream surfaces was employed to obtain meridional flow fields and the point-by-point integration method was employed to draw blade camber lines. Blades are thickened as well as blade leading edges are smoothed in the conformal mapping surface. Subsequently the internal fields of the whole flow passage of the designed pump were simulated by using RANS equations with RNG k-ε two-equation turbulent model. The results show that, compared with the 211-80 model, the hydraulic efficiency of the designed pump at the optimal flow rate increases 9.1%. The hydraulic efficiency of designed pump in low flow rate condition (78% designed flow rate) increases 6.46%. The hydraulic efficiency in high flow rate areas increases obviously and there is no bad phenomenon of suddenly decrease of hydraulic efficiency in model pump. From the distributions of velocity and pressure fields, it can be seen that the flow in impeller is uniform and the increase of pressure is gentle. There are no obvious impact phenomenon on impeller inlet and obvious wake shedding vortex phenomenon from impeller outlet to guide vanes inlet.

  8. Marangoni Flow and Surface Tension of High Temperature Melts

    Science.gov (United States)

    Hibiya, Taketoshi; Ozawa, Shumpei

    Marangoni flow plays an important role in the heat and mass transport for highly value-added high-temperature processes, such as crystal growth, welding, casting, and electron beam melting. For silicon single crystal growth, the effect of the oscillatory Marangoni flow on the introduction of growth striation was discussed by Chen and Wilcox for the first time in 1972 [1]. The existence of the Marangoni flow within molten silicon was proved through microgravity experiments in space on board a sounding rocket in 1983 by Eyer et al. [2], who found formation of growth striation in single crystals even under microgravity, where buoyancy-driven flow was suppressed. To explain the Marangoni effect at the melt surface, surface tension is essential. Keene [3] discussed the oxygen contamination in the surface tension measurement and recommended the use of a levitation technique, which is a containerless process and assures the contamination-free condition from measurement devices. It is well known that flow direction in the weld pool is dependent on surface contamination and that this is related to weldability [4, 5]. Flow direction is controlled by the temperature coefficient of surface tension for molten steels; contaminants are oxygen and sulfur. In the electron beam button melting system, the Marangoni flow is dominant because of intense heating at the melt surface [5]. In this chapter, surface tension of high temperature metallic melts is discussed from the viewpoint of the Marangoni effect in the value-added high temperature processes, particularly from the viewpoint of the effect of oxygen and sulfur. Theoretical treatment for oxygen adsorption is also discussed.

  9. Expanding the range for predicting critical flow rates of gas wells producing from normally pressured waterdrive reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Upchurch, E.R. (Thums Long Beach Co. (US))

    1989-08-01

    The critical flow rate of a gas well is the minimum flow rate required to prevent accumulation of liquids in the tubing. Theoretical models currently available for estimating critical flow rates are restricted to wells with water/gas ratios less than 150bbl/MMcf (0.84 X 10/sup -3/ m/sup 3//m/sup 3/). For wells producing at higher water/gas ratios from normally pressured waterdrive reservoirs, a method of estimating critical flow rates is derived through use of an empirical multiphase-flow correlation.

  10. Research on Gas-liquid Flow Rate Optimization in Foam Drilling

    Science.gov (United States)

    Gao, B. K.; Sun, D. G.; Jia, Z. G.; Huang, Z. Q.

    2010-03-01

    With the advantages of less gas consumption, higher carrying rocks ability, lower leakage and higher penetration rate, foam drilling is widely used today in petroleum industry. In the process of foam underbalanced drilling, the mixture of gas, liquid and cuttings flows upwards through the annular, so it is a typical gas-liquid-solid multi-phase flow. In order to protect the reservoir and avoid borehole wall collapsing during foam drilling, it is crucial to ensure that the bottom hole pressure is lower than the formation pressure and higher than the formation collapse pressure, and in the mean time, foam drilling fluid in the whole wellbore should be in the best foam quality stage in order to have sufficient capacity to carry cuttings. In this paper, main relations between bottom hole pressure and gas-liquid injecting rate are analyzed with the underbalanced multiphase flow models. And in order to obtain precise flow pattern and flow pressure, the whole well bore is spatial meshed and iterative method is used. So, a convenient safety window expressed by gas-liquid injecting rate is obtained instead of that by bottom hole pressure. Finally, a foam drilling example from a block in Yemen is presented; the drilling results show that this method is reliable and practical.

  11. Effects of Gas Flow Rate on the Discharge Characteristics of a DC Excited Plasma Jet

    Science.gov (United States)

    Li, Xuechen; Jia, Pengying; Di, Cong; Bao, Wenting; Zhang, Chunyan

    2015-09-01

    A direct current (DC) source excited plasma jet consisting of a hollow needle anode and a plate cathode has been developed to form a diffuse discharge plume in ambient air with flowing argon as the working gas. Using optical and electrical methods, the discharge characteristics are investigated for the diffuse plasma plume. Results indicate that the discharge has a pulse characteristic, under the excitation of a DC voltage. The discharge pulse corresponds to the propagation process of a plasma bullet travelling from the anode to the cathode. It is found that, with an increment of the gas flow rate, both the discharge plume length and the current peak value of the pulsed discharge decrease in the laminar flow mode, reach their minima at about 1.5 L/min, and then slightly increase in the turbulent mode. However, the frequency of the pulsed discharge increases in the laminar mode with increasing the argon flow rate until the argon flow rate equals to about 1.5 L/min, and then slightly decreases in the turbulent mode. supported by National Natural Science Foundation of China (Nos. 10805013, 11375051), Funds for Distinguished Young Scientists of Hebei Province, China (No. A2012201045), Department of Education for Outstanding Youth Project of China (No. Y2011120), and Youth Project of Hebei University of China (No. 2011Q14)

  12. Cerberus Fossae and Elysium Planitia Lavas, Mars: Source Vents, Flow Rates, Edifice Styles and Water Interactions

    Science.gov (United States)

    Sakimoto, S. E. H.; Gregg, T. K. P.

    2004-01-01

    The Cerberus Fossae and Elysium Planitia regions have been suggested as some of the youngest martian surfaces since the Viking mission, although there was doubt whether the origins were predominantly volcanic or fluvial. The Mars Global Surveyor and Mars Odyssey Missions have shown that the region is certainly young in terms of the topographic preservation and the youthful crater counts (e.g. in the tens to a few hundred million yrs.). Numerous authors have shown that fluvial and volcanic features share common flow paths and vent systems, and that there is evidence for some interaction between the lava flows and underlying volatiles as well as the use by lavas and water of the same vent system. Given the youthful age and possible water-volcanism interaction environment, we'd like constraints on water and volcanic flux rates and interactions. Here, we model ranges of volcanic flow rates where we can well-constrain them, and consider the modest flow rate results results in context with local eruption styles, and track vent locations, edifice volumes, and flow sources and data.

  13. Performance of PEM fuel cells stack as affected by number of cell and gas flow-rate

    Science.gov (United States)

    Syampurwadi, A.; Onggo, H.; Indriyati; Yudianti, R.

    2017-03-01

    The proton exchange membrane fuel cell (PEMFC) is a promising technology as an alternative green energy due to its high power density, low operating temperatures, low local emissions, quiet operation and fast start up-shutdown. In order to apply fuel cell as portable power supply, the performance investigation of small number of cells is needed. In this study, PEMFC stacks consisting of 1, 3, 5 and 7-cells with an active area of 25 cm2 per cell have been designed and developed. Their was evaluated in variation of gas flow rate. The membrane electrode assembly (MEA) was prepared by hot-pressing commercial gas diffusion electrodes (Pt loading 0.5 mg/cm2) on pre-treated Nafion 117 membrane. The stacks were constructed using bipolar plates in serpentine pattern and Z-type gas flow configuration. The experimental results were presented as polarization and power output curves which show the effects of varying number of cells and H2/O2 flow-rates on the PEMFC performance. The experimental results showed that not only number of cells and gas flow-rates affected the fuel cells performance, but also the operating temperature as a result of electrochemistry reaction inside the cell.

  14. High-Rate Strong-Signal Quantum Cryptography

    Science.gov (United States)

    Yuen, Horace P.

    1996-01-01

    Several quantum cryptosystems utilizing different kinds of nonclassical lights, which can accommodate high intensity fields and high data rate, are described. However, they are all sensitive to loss and both the high rate and the strong-signal character rapidly disappear. A squeezed light homodyne detection scheme is proposed which, with present-day technology, leads to more than two orders of magnitude data rate improvement over other current experimental systems for moderate loss.

  15. Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Christensen, H

    1991-01-01

    Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage uni.......0001). The synchronism of the nocturnal subcutaneous hyperemia and the decrease in systemic mean arterial blood pressure point to a common, possibly central nervous or humoral, eliciting mechanism.......Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit...

  16. The Effect of the Volume Flow rate on the Efficiency of a Solar Collector

    DEFF Research Database (Denmark)

    Fan, Jianhua; Shah, Louise Jivan; Furbo, Simon

    rates. Theoretically, a simplified model of the solar collector panel is built by means of the CFD (Computational Fluid Dynamics) code Fluent, where the geometry of the collector panel except the casing is fully modeled. Both lateral and longitudinal heat conduction in the absorber fins, the heat...... transfer from the absorber to the solar collector fluid and the heat loss from the absorber are considered. Flow and temperature distribution in the collector panel are investigated with buoyancy effect. Measurements are carried out with the solar collector panel. Collector efficiencies are measured......The flow distribution inside a collector panel with an area of 12.5 m² and with 16 parallel connected horizontal fins and the effect of the flow nonuniformity on the risk of boiling and on the collector efficiency have been theoretically and experimentally investigated for different volume flow...

  17. Syringe-pump-induced fluctuation in all-aqueous microfluidic system implications for flow rate accuracy.

    Science.gov (United States)

    Li, Zida; Mak, Sze Yi; Sauret, Alban; Shum, Ho Cheung

    2014-02-21

    We report a new method to display the minute fluctuations induced by syringe pumps on microfluidic flows by using a liquid-liquid system with an ultralow interfacial tension. We demonstrate that the stepper motor inside the pump is a source of fluctuations in microfluidic flows by comparing the frequencies of the ripples observed at the interface to that of the pulsation of the stepper motor. We also quantify the fluctuations induced at different flow rates, using syringes of different diameters, and using different syringe pumps with different advancing distances per step. Our work provides a way to predict the frequency of the fluctuation that the driving syringe pump induces on a microfluidic system and suggests that syringe pumps can be a source of fluctuations in microfluidic flows, thus contributing to the polydispersity of the resulting droplets.

  18. Skin friction measurements in high temperature high speed flows

    Science.gov (United States)

    Schetz, J. A.; Diller, Thomas E.; Wicks, A. L.

    1992-01-01

    An experimental investigation was conducted to measure skin friction along the chamber walls of supersonic combustors. A direct force measurement device was used to simultaneously measure an axial and transverse component of the small tangential shear force passing over a non-intrusive floating element. The floating head is mounted to a stiff cantilever beam arrangement with deflection due to the flow on the order of 0.00254 mm (0.0001 in.). This allowed the instrument to be a non-nulling type. A second gauge was designed with active cooling of the floating sensor head to eliminate non-uniform temperature effects between the sensor head and the surrounding wall. Samples of measurements made in combustor test facilities at NASA Langley Research Center and at the General Applied Science Laboratory (GASL) are presented. Skin friction coefficients between 0.001 - 0.005 were measured dependent on the facility and measurement location. Analysis of the measurement uncertainties indicate an accuracy to within +/- 10-15 percent of the streamwise component.

  19. Review of flow rate estimates of the Deepwater Horizon oil spill

    Science.gov (United States)

    McNutt, Marcia K.; Camilli, Rich; Crone, Timothy J.; Guthrie, George D.; Hsieh, Paul A.; Ryerson, Thomas B.; Savas, Omer; Shaffer, Frank

    2012-01-01

    The unprecedented nature of the Deepwater Horizon oil spill required the application of research methods to estimate the rate at which oil was escaping from the well in the deep sea, its disposition after it entered the ocean, and total reservoir depletion. Here, we review what advances were made in scientific understanding of quantification of flow rates during deep sea oil well blowouts. We assess the degree to which a consensus was reached on the flow rate of the well by comparing in situ observations of the leaking well with a time-dependent flow rate model derived from pressure readings taken after the Macondo well was shut in for the well integrity test. Model simulations also proved valuable for predicting the effect of partial deployment of the blowout preventer rams on flow rate. Taken together, the scientific analyses support flow rates in the range of ~50,000–70,000 barrels/d, perhaps modestly decreasing over the duration of the oil spill, for a total release of ~5.0 million barrels of oil, not accounting for BP's collection effort. By quantifying the amount of oil at different locations (wellhead, ocean surface, and atmosphere), we conclude that just over 2 million barrels of oil (after accounting for containment) and all of the released methane remained in the deep sea. By better understanding the fate of the hydrocarbons, the total discharge can be partitioned into separate components that pose threats to deep sea vs. coastal ecosystems, allowing responders in future events to scale their actions accordingly.

  20. Flow perfusion rate modulates cell deposition onto scaffold substrate during cell seeding.

    Science.gov (United States)

    Campos Marín, A; Brunelli, M; Lacroix, D

    2017-11-29

    The combination of perfusion bioreactors with porous scaffolds is beneficial for the transport of cells during cell seeding. Nonetheless, the fact that cells penetrate into the scaffold pores does not necessarily imply the interception of cells with scaffold substrate and cell attachment. An in vitro perfusion system was built to relate the selected flow rate with seeding efficiency. However, the in vitro model does not elucidate how the flow rate affects the transport and deposition of cells onto the scaffold. Thus, a computational model was developed mimicking in vitro conditions to identify the mechanisms that bring cells to the scaffold from suspension flow. Static and dynamic cell seeding configurations were investigated. In static seeding, cells sediment due to gravity until they encounter the first obstacle. In dynamic seeding, 12, 120 and 600 [Formula: see text] flow rates were explored under the presence or the absence of gravity. Gravity and secondary flow were found to be key factors for cell deposition. In vitro and in silico seeding efficiencies are in the same order of magnitude and follow the same trend with the effect of fluid flow; static seeding results in higher efficiency than dynamic perfusion although irregular spatial distribution of cells was found. In dynamic seeding, 120 [Formula: see text] provided the best seeding results. Nevertheless, the perfusion approach reports low efficiencies for the scaffold used in this study which leads to cell waste and low density of cells inside the scaffold. This study suggests gravity and secondary flow as the driving mechanisms for cell-scaffold deposition. In addition, the present in silico model can help to optimize hydrodynamic-based seeding strategies prior to experiments and enhance cell seeding efficiency.

  1. Thermal Mechanisms for High Amplitude Aerodynamic Flow Control (YIP 2012)

    Science.gov (United States)

    2016-04-15

    high speed, high Reynolds number jets (see Samimy et al. 2010 and references therein). In this case, localized arc filament plasma actuators (LAFPAs...fundamentally different from the widely studied ac-DBD plasma actuator which functions through momentum transfer between ionized and neutral species... arc plasmas has been demonstrated in high-speed flows having turbulent boundary layers and negligible pressure gradient (Lazar et al. 2008; Kearney

  2. Direct Numerical Simulation of Disperse Multiphase High-Speed Flows

    Energy Technology Data Exchange (ETDEWEB)

    Nourgaliev, R R; Dinh, T N; Theofanous, T G; Koning, J M; Greenman, R M; Nakafuji, G T

    2004-02-17

    A recently introduced Level-Set-based Cartesian Grid (LSCG) Characteristics-Based Matching (CBM) method is applied for direct numerical simulation of shock-induced dispersal of solid material. The method incorporates the latest advancements in the level set technology and characteristics-based numerical methods for solution of hyperbolic conservation laws and boundary treatment. The LSCG/CBM provides unique capabilities to simulate complex fluid-solid (particulate) multiphase flows under high-speed flow conditions and taking into account particle-particle elastic and viscoelastic collisions. The particular emphasis of the present study is placed on importance of appropriate modeling of particle-particle collisions, which are demonstrated to crucially influence the global behavior of high-speed multiphase particulate flows. The results of computations reveal the richness and complexity of flow structures in compressible disperse systems, due to dynamic formation of shocks and contact discontinuities, which provide an additional long-range interaction mechanism in dispersed high-speed multiphase flows.

  3. Analysis of arrayed nanocapacitor formed on nanorods by flow-rate interruption atomic layer deposition

    Science.gov (United States)

    Lin, Bo-Cheng; Ku, Ching-Shun; Lee, Hsin-Yi; Chakroborty, Subhendu; Wu, Albert T.

    2017-12-01

    Flow-rate interruption (FRI) atomic layer deposition (ALD) technique was adopted to fabricate AZO/Al2O3/AZO thin film on a ZnO nanorod array template at low temperature. The high quality amorphous dielectric Al2O3 layer was deposited at 50 °C. The template with an average of 0.73 μm in length was made by a simple hydrothermal method on a c-plane sapphire with an AZO seed layer. Using Polystyrene (PS) microspheres were served as a mask to form vertical and well-aligned ZnO nanostructures. Field-emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) images show ALD to have achieved good step coverage and thickness control in the thin films structure coating. The capacitance density of the arrayed template nanocapacitor increased more than 100% than those of the thin film capacitor at an applied frequency of 10 kHz. These results suggest that the ZnO-arrayed template could enhance energy storage capability by providing significant surface area. This structure provides a concept for high surface-area nanocapacitor applications.

  4. Energy policy act transportation study: Interim report on natural gas flows and rates

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-11-17

    This report, Energy Policy Act Transportation Study: Interim Report on Natural Gas Flows and Rates, is the second in a series mandated by Title XIII, Section 1340, ``Establishment of Data Base and Study of Transportation Rates,`` of the Energy Policy Act of 1992 (P.L. 102--486). The first report Energy Policy Act Transportation Study: Availability of Data and Studies, was submitted to Congress in October 1993; it summarized data and studies that could be used to address the impact of legislative and regulatory actions on natural gas transportation rates and flow patterns. The current report presents an interim analysis of natural gas transportation rates and distribution patterns for the period from 1988 through 1994. A third and final report addressing the transportation rates and flows through 1997 is due to Congress in October 2000. This analysis relies on currently available data; no new data collection effort was undertaken. The need for the collection of additional data on transportation rates will be further addressed after this report, in consultation with the Congress, industry representatives, and in other public forums.

  5. Evaluation of Peak Expiratory Flow rates (PEFR) of Workers in a ...

    African Journals Online (AJOL)

    Method: In this descriptive cross-sectional study, 105 workers of a cement company who presented for the annual fitness to work exercise were sampled and had their peak expiratory flow rates measured using a spirometer. Data were also collected using structured interviewer-administered questionnaires and a walk ...

  6. Flow rate through microfilters: Influence of the pore size distribution, hydrodynamic interactions, wall slip, and inertia

    DEFF Research Database (Denmark)

    Jensen, Kaare Hartvig; Valente, Andre X. C. N.; Stone, Howard A.

    2014-01-01

    to obtain an analytical formula for the pressure drop across the microfilter versus the flow rate that accounts for the non-uniform distribution of pore sizes, the hydrodynamic interactions between the pores given their layout pattern, and wall slip. Further, we discuss inertial effects and their order...

  7. Influence of nitrogen flow rates on materials properties of CrNx films ...

    Indian Academy of Sciences (India)

    Abstract. Chromium nitride (CrN) hard thin films were deposited on different substrates by reactive direct current. (d.c.) magnetron sputtering with different nitrogen flow rates. The X-ray diffraction patterns showed mixed Cr2N and CrN phases. The variations in structural parameters are discussed. The grain size increased ...

  8. Diurnal variations in lower leg subcutaneous blood flow rate in patients with chronic venous leg ulcers

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Kristensen, J K

    1991-01-01

    The blood flow rate in subcutaneous adipose tissue was measured on the lower legs of 11 patients with chronic lower-leg venous insufficiency and ulceration and in eight age-matched control subjects for 12-20 h, under ambulatory conditions, using the 133Xe wash-out technique with portable Cadmium...

  9. Fabric inlet stratifiers for solar tanks with different volume flow rates

    DEFF Research Database (Denmark)

    Andersen, Elsa; Furbo, Simon

    2006-01-01

    in the centre of a glass tank (400 x 400 x 900 mm). The forced volume flow rate is in the range of 6 – 10 l/min, and water enters the stratification pipe from the bottom of the tank. The thermal behaviour of the stratification pipes is investigated for different realistic operation conditions...

  10. Lower urinary tract symptoms and urinary flow rates in female patients with hyperthyroidism.

    Science.gov (United States)

    Ho, Chen-Hsun; Chang, Tien-Chun; Guo, Ya-Jun; Chen, Shyh-Chyan; Yu, Hong-Jeng; Huang, Kuo-How

    2011-01-01

    To investigate lower urinary tract symptoms (LUTS) and voiding function in a cohort of hyperthyroid women. The autonomic nervous system (ANS) imbalance has been thought to cause LUTS in hyperthyroidism. Between January 2008 and December 2008, 65 newly diagnosed, untreated female hyperthyroid patients were enrolled in this study. Another 62 age-matched healthy women were enrolled as a control group. Demographics, LUTS, urinary flow rates, hyperthyroid symptoms, and serum levels of thyroid hormones were recorded before and after the medical treatment for hyperthyroidism. Compared with the control group, the hyperthyroid patients had a higher mean symptom score of frequency (1.15 ± 1.75 vs 0.31 ± 1.05, P = .01), incomplete emptying (0.91 ± 1.47 vs 0.29 ± 1.12, P = .02), straining (1.05 ± 0.85 vs 0.27 ± 0.51, P flow rates improved significantly. The severity of LUTS was associated with neither serum levels of thyroid hormone nor other hyperthyroid symptoms. Hyperthyroid women have worse LUTS and lower peak flow rates than healthy controls. However, the severity of LUTS is only mild (IPSS flow rates improve after the treatment for hyperthyroidism. The exact mechanisms of LUTS and/or lower urinary tract dysfunction in hyperthyroidism require further investigation. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Flow rates and pressure profiles for one to four axially alined Borda inlets

    Science.gov (United States)

    Hendricks, R. C.; Stetz, T. T.

    1984-01-01

    Choked flow rate and pressure profile data were taken on sequential, axially alined inlets of the Borda type. The configurations consisted of two to four inlets spaced 0.8 and 30 diameters apart. At a spacing of 30 diameters the reduced flow rate appeared to follow the simple empirical relation G sub r/G sub r,1=N(-b), where G sub r,1 is the reduced flow rate for a single inlet; N is the number of inlets; and b, which is weakly temperature dependent, is approximately 0.4. The relation is in reasonable agreement with an analysis of the N-inlet configuration. At a spacing of 30 diameters the pressure profiles dropped sharply at the entrance and partially recovered within each inlet somewhat independently of N. Jetting through the last Borda was common at low temperatures. At a spacing of 0.8 diameter fluid jetting was prevalent at low temperatures for each configuration studied and flow rates were the same as that for a single inlet.

  12. Glucose Pump Test can be Used to Measure Blood Flow Rate of ...

    African Journals Online (AJOL)

    2018-02-07

    Feb 7, 2018 ... Purpose: In chronic hemodialysis patients, the low flow of vascular access may leads to inadequate dialysis, increased rate of hospitalization, morbidity, and mortality. It was found that surveillance should be performed for native arteriovenous (AV) should not be performed for AV graft in various studies.

  13. Influence of nitrogen flow rates on materials properties of CrNx films ...

    Indian Academy of Sciences (India)

    Chromium nitride (CrN) hard thin films were deposited on different substrates by reactive direct current (d.c.) magnetron sputtering with different nitrogen flow rates. The X-ray diffraction patterns showed mixed Cr2N and CrN phases. The variations in structural parameters are discussed. The grain size increased with ...

  14. Nocturnal variations in subcutaneous blood flow rate in lower leg of normal human subjects

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Jørgensen, B

    1991-01-01

    Subcutaneous adipose tissue blood flow rate was measured in the lower leg of 22 normal human subjects over 12- to 20-h ambulatory conditions. The 133Xe washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used. The tracer depot was applied on the medial aspect...

  15. Performance and radial distribution profiles of a variable flow rate sprinkler developed for precision irrigation

    Directory of Open Access Journals (Sweden)

    Robson André Armindo

    2012-04-01

    Full Text Available Variable rate sprinklers (VRS have been developed to promote localized water application of irrigated areas. In Precision Irrigation, VRS permits better control of flow adjustment and, at the same time, provides satisfactory radial distribution profiles for various pressures and flow rates are really necessary. The objective of this work was to evaluate the performance and radial distribution profiles of a developed VRS which varies the nozzle cross sectional area by moving a pin in or out using a stepper motor. Field tests were performed under different conditions of service pressure, rotation angles imposed on the pin and flow rate which resulted in maximal water throw radiuses ranging from 7.30 to 10.38 m. In the experiments in which the service pressure remained constant, the maximal throw radius varied from 7.96 to 8.91 m. Averages were used of repetitions performed under conditions without wind or with winds less than 1.3 m s-1. The VRS with the four stream deflector resulted in greater water application throw radius compared to the six stream deflector. However, the six stream deflector had greater precipitation intensities, as well as better distribution. Thus, selection of the deflector to be utilized should be based on project requirements, respecting the difference in the obtained results. With a small opening of the nozzle, the VRS produced small water droplets that visually presented applicability for foliar chemigation. Regarding the comparison between the estimated and observed flow rates, the stepper motor produced excellent results.

  16. PROGRESSIVE MUSCLE RELAXATION INCREASE PEAK EXPIRATORY FLOW RATE ON CHRONIC OBSTRUCTIVE PULMONARY DISEASE PATIENTS

    Directory of Open Access Journals (Sweden)

    Tintin Sukartini

    2017-07-01

    Full Text Available Introduction: Limited progressive air flow in Chronic Obstructive Pulmonary Disease (COPD can caused by small airway disease (bronchiolitis obstructive and loss of elasticity of the lung (emphysema. Further it can be decreasing the quality of life in COPD patients because dyspnea and uncomfortable in activity. Progressive muscle relaxation (PMR is one of the relaxation technique that can repair pulmonary ventilation by decreasing chronic constriction of the respiratory muscles. The objective of this study was to analyze the effect of progressive muscle relaxation on raised peak expiratory flow rate (PEFR. Method: A pre-experimental one group pre-post test design was used in this study. Population was all of the COPD patients at Pulmonary Specialist Polyclinic Dr Mohamad Soewandhie Surabaya. There were 8 respondents taken by using purposive sampling. PEFR was counted by using peak flow meter every six day. Data were analyzed by using Paired t-Test with significance level  p≤0.05. Result: The result showed that PMR had significance level on increasing of PEFR (p=0.012. Discussion: It can be concluded that PMR has an effect on raise PEFR. Further studies are recommended to measure the effect of PMR on respiratory rate (RR, heart rate (HR subjective dyspnoe symptoms, forced expiration volume on the first minute (FEV1 and mid maximum flow rate (MMFR in COPD patients.

  17. The control of self-propelled microjets inside a microchannel with time-varying flow rates

    NARCIS (Netherlands)

    Khalil, I.S.M.; Magdanz, Veronika; Sanchez, Samuel; Schmidt, Oliver S.; Misra, Sarthak

    We demonstrate the closed-loop motion control of self-propelled microjets inside a fluidic microchannel. The motion control of the microjets is achieved in hydrogen peroxide solution with time-varying flow rates, under the influence of the controlled magnetic fields and the self-propulsion force.

  18. Sympathetic nervous system activation, arterial shear rate, and flow-mediated dilation.

    NARCIS (Netherlands)

    Thijssen, D.H.J.; Atkinson, C.L.; Ono, K.; Sprung, V.S.; Spence, A.L.; Pugh, C.J.; Green, D.J.

    2014-01-01

    The aim of this study was to examine the contribution of arterial shear to changes in flow-mediated dilation (FMD) during sympathetic nervous system (SNS) activation in healthy humans. Ten healthy men reported to our laboratory four times. Bilateral FMD, shear rate (SR), and catecholamines were

  19. Determination of vibration frequency depending on abrasive mass flow rate during abrasive water jet cutting

    Czech Academy of Sciences Publication Activity Database

    Hreha, P.; Radvanská, A.; Hloch, Sergej; Peržel, V.; Krolczyk, G.; Monková, K.

    2014-01-01

    Roč. 77, 1-4 (2014), s. 763-774 ISSN 0268-3768 Institutional support: RVO:68145535 Keywords : Abrasive water jet * Abrasive mass flow rate * Vibration Subject RIV: JQ - Machines ; Tools Impact factor: 1.458, year: 2014 http://link.springer.com/article/10.1007%2Fs00170-014-6497-9#page-1

  20. Glucose Pump Test can be Used to Measure Blood Flow Rate of ...

    African Journals Online (AJOL)

    Purpose: In chronic hemodialysis patients, the low flow of vascular access may leads to inadequate dialysis, increased rate of hospitalization, morbidity, and mortality. It was found that surveillance should be performed for native arteriovenous (AV) should not be performed for AV graft in various studies. However ...

  1. High energy density Z-pinch plasmas using flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Shumlak, U., E-mail: shumlak@uw.edu; Golingo, R. P., E-mail: shumlak@uw.edu; Nelson, B. A., E-mail: shumlak@uw.edu; Bowers, C. A., E-mail: shumlak@uw.edu; Doty, S. A., E-mail: shumlak@uw.edu; Forbes, E. G., E-mail: shumlak@uw.edu; Hughes, M. C., E-mail: shumlak@uw.edu; Kim, B., E-mail: shumlak@uw.edu; Knecht, S. D., E-mail: shumlak@uw.edu; Lambert, K. K., E-mail: shumlak@uw.edu; Lowrie, W., E-mail: shumlak@uw.edu; Ross, M. P., E-mail: shumlak@uw.edu; Weed, J. R., E-mail: shumlak@uw.edu [Aerospace and Energetics Research Program, University of Washington, Seattle, Washington, 98195-2250 (United States)

    2014-12-15

    The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes – Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and

  2. Highly efficient resistive plate chambers for high rate environment

    CERN Document Server

    Cwiok, M; Górski, M; Królikowski, J

    1999-01-01

    The full scale prototype of an inverted double gap RPC module for ME-1/1 station of the CMS detector was tested in the gamma irradiation facility at the CERN SPS muon beam. The chamber made of medium resistivity bakelite and filled with "green gas" mixture of C /sub 2/H/sub 2/F/sub 4//iso-butane/SF/sub 6/ has wide efficiency plateau and good timing properties when operated in avalanche mode under continuous irradiation with strong /sup 137/Cs source for rates up to about 5 kHz/cm/sup 2//gap. (10 refs).

  3. Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes

    Science.gov (United States)

    Zouache, Moussa A.; Eames, Ian; Samsudin, Amir

    2016-01-01

    In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac0.67, where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma. PMID:26990431

  4. Scale dependence of the alignment between strain rate and rotation in turbulent shear flow

    KAUST Repository

    Fiscaletti, D.

    2016-10-24

    The scale dependence of the statistical alignment tendencies of the eigenvectors of the strain-rate tensor e(i), with the vorticity vector omega, is examined in the self-preserving region of a planar turbulent mixing layer. Data from a direct numerical simulation are filtered at various length scales and the probability density functions of the magnitude of the alignment cosines between the two unit vectors vertical bar e(i) . (omega) over cap vertical bar are examined. It is observed that the alignment tendencies are insensitive to the concurrent large-scale velocity fluctuations, but are quantitatively affected by the nature of the concurrent large-scale velocity-gradient fluctuations. It is confirmed that the small-scale (local) vorticity vector is preferentially aligned in parallel with the large-scale (background) extensive strain-rate eigenvector e(1), in contrast to the global tendency for omega to be aligned in parallelwith the intermediate strain-rate eigenvector [Hamlington et al., Phys. Fluids 20, 111703 (2008)]. When only data from regions of the flow that exhibit strong swirling are included, the so-called high-enstrophy worms, the alignment tendencies are exaggerated with respect to the global picture. These findings support the notion that the production of enstrophy, responsible for a net cascade of turbulent kinetic energy from large scales to small scales, is driven by vorticity stretching due to the preferential parallel alignment between omega and nonlocal e(1) and that the strongly swirling worms are kinematically significant to this process.

  5. Void fraction in horizontal bulk flow boiling at high flow qualities

    Energy Technology Data Exchange (ETDEWEB)

    Collado, Fancisco J.; Monne, Carlos [Dpto. de Ingenieria Mecanica, Universidad de Zaragoza-CPS, Maria de Luna 3, 50018-Zaragoza (Spain); Pascau, Antonio [Dpto. de Ciencia de los Materiales y Fluidos, Universidad de Zaragoza-CPS, Maria de Luna 3, 50018-Zaragoza (Spain)

    2008-04-15

    In this work, a new thermodynamic prediction of the vapor void fraction in bulk flow boiling, which is the core process of many energy conversion systems, is analyzed. The current heat balance is based on the flow quality, which is closely related to the measured void fraction, although some correlation for the vapor-liquid velocity ratio is needed. So here, it is suggested to work with the 'static' or thermodynamic quality, which is directly connected to the void fraction through the densities of the phases. Thus, the relation between heat and the mixture enthalpy (here based on the thermodynamic quality instead of the flow one) should be analyzed in depth. The careful void fraction data taken by Thom during the 'Cambridge project' for horizontal saturated flow boiling with high flow qualities ({<=}0.8) have been used for this analysis. As main results, first, we have found that the applied heat and the increment of the proposed thermodynamic enthalpy mixture throughout the heated duct do not agree, and for closure, a parameter is needed. Second, it has been checked that this parameter is practically equal to the classic velocity ratio or 'slip' ratio, suggesting that it should be included in a true thermodynamic heat balance. Furthermore, it has been clearly possible to improve the 'Cambridge project' correlations for the 'slip' ratio, here based on inlet pressure and water velocity, and heat flux. The calculated void fractions compare quite well with the measured ones. Finally, the equivalence of the suggested new heat balance with the current one through the 'slip' ratio is addressed. Highlighted is the same new energetic relation for saturated flow boiling that has been recently confirmed by the authors for Knights data, also taken during the 'Cambridge project', which include not only horizontal but also vertical upwards flows with moderate outlet flow quality ({<=}0.2). (author)

  6. Measurements of granular flow dynamics with high speed digital images

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jingeol [Univ. of Florida, Gainesville, FL (United States)

    1994-01-01

    The flow of granular materials is common to many industrial processes. This dissertation suggests and validates image processing algorithms applied to high speed digital images to measure the dynamics (velocity, temperature and volume fraction) of dry granular solids flowing down an inclined chute under the action of gravity. Glass and acrylic particles have been used as granular solids in the experiment. One technique utilizes block matching for spatially averaged velocity measurements of the glass particles. This technique is compared with the velocity measurement using an optic probe which is a conventional granular flow velocity measurement device. The other technique for measuring the velocities of individual acrylic particles is developed with correspondence using a Hopfield network. This technique first locates the positions of particles with pattern recognition techniques, followed by a clustering technique, which produces point patterns. Also, several techniques are compared for particle recognition: synthetic discriminant function (SDF), minimum average correlation energy (MACE) filter, modified minimum average correlation energy (MMACE) filter and variance normalized correlation. The author proposes an MMACE filter which improves generalization of the MACE filter by adjusting the amount of averaged spectrum of training images in the spectrum whitening stages of the MACE filter. Variance normalized correlation is applied to measure the velocity and temperature of flowing glass particles down the inclined chute. The measurements are taken for the steady and wavy flow and qualitatively compared with a theoretical model of granular flow.

  7. Minimum state for high Reynolds and Peclet number turbulent flows

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Ye, E-mail: yezhou@llnl.go [Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94551 (United States); Buckingham, A.C. [Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94551 (United States); Bataille, F. [PROMES-CNRS, Tecnosud, 66100 Perpignan (France); Mathelin, L. [LIMSI-CNRS, BP 133, 91403 Orsay (France)

    2009-07-20

    Direct numerical simulations (DNS) or experiments for the very high Reynolds (Re) and Peclet (Pe) number flows commonly exceed the resolution possible even when use is made of the most advanced computer capability or most sophisticated diagnostics and physical capabilities of advanced laboratory facilities. In practice use is made of statistical flow data bases developed at the highest Re and Pe levels achievable within the currently available facility limitations. In addition, there is presently no metric to indicate whether and how much of the fully resolved physics of the flow of interest has been captured within the facilities available. In this Letter the authors develop the necessary metric criteria for homogeneous, isotropic and shear layer flows. It is based on establishing a smaller subset of the total range of dynamic scale interactions that will still faithfully reproduce all of the essential, significant, influences of the larger range of scale interactions. The work identifies a minimum significant Re and Pe level that must be obtained by DNS or experiment in order to capture all of the significant dynamic influences in data which is then scaleable to flows of interest. Hereafter this is called the minimum state. Determination of the minimum state is based on finding a minimum scale separation for the energy-containing scales of the flow and scalar fields sufficient to prevent contamination by interaction with the (non-universal) velocity dissipation and scalar diffusivity inertial range scale limits.

  8. Real-time High-fidelity Surface Flow Simulation.

    Science.gov (United States)

    Ren, Bo; Yuan, Tailing; Li, Chenfeng; Xu, Kun; Hu, Shi-Min

    2017-06-30

    Surface flow phenomena, such as rain water flowing down a tree trunk and progressive water front in a shower room, are common in real life. However, compared with the 3D spatial fluid flow, these surface flow problems have been much less studied in the graphics community. To tackle this research gap, we present an efficient, robust and high-fidelity simulation approach based on the shallow-water equations. Specifically, the standard shallow-water flow model is extended to general triangle meshes with a feature-based bottom friction model, and a series of coherent mathematical formulations are derived to represent the full range of physical effects that are important for real-world surface flow phenomena. In addition, by achieving compatibility with existing 3D fluid simulators and by supporting physically realistic interactions with multiple fluids and solid surfaces, the new model is flexible and readily extensible for coupled phenomena. A wide range of simulation examples are presented to demonstrate the performance of the new approach.

  9. Next Generation Flow for highly sensitive and standardized detection of minimal residual disease in multiple myeloma.

    Science.gov (United States)

    Flores-Montero, J; Sanoja-Flores, L; Paiva, B; Puig, N; García-Sánchez, O; Böttcher, S; van der Velden, V H J; Pérez-Morán, J-J; Vidriales, M-B; García-Sanz, R; Jimenez, C; González, M; Martínez-López, J; Corral-Mateos, A; Grigore, G-E; Fluxá, R; Pontes, R; Caetano, J; Sedek, L; Del Cañizo, M-C; Bladé, J; Lahuerta, J-J; Aguilar, C; Bárez, A; García-Mateo, A; Labrador, J; Leoz, P; Aguilera-Sanz, C; San-Miguel, J; Mateos, M-V; Durie, B; van Dongen, J J M; Orfao, A

    2017-10-01

    Flow cytometry has become a highly valuable method to monitor minimal residual disease (MRD) and evaluate the depth of complete response (CR) in bone marrow (BM) of multiple myeloma (MM) after therapy. However, current flow-MRD has lower sensitivity than molecular methods and lacks standardization. Here we report on a novel next generation flow (NGF) approach for highly sensitive and standardized MRD detection in MM. An optimized 2-tube 8-color antibody panel was constructed in five cycles of design-evaluation-redesign. In addition, a bulk-lysis procedure was established for acquisition of ⩾107 cells/sample, and novel software tools were constructed for automatic plasma cell gating. Multicenter evaluation of 110 follow-up BM from MM patients in very good partial response (VGPR) or CR showed a higher sensitivity for NGF-MRD vs conventional 8-color flow-MRD -MRD-positive rate of 47 vs 34% (P=0.003)-. Thus, 25% of patients classified as MRD-negative by conventional 8-color flow were MRD-positive by NGF, translating into a significantly longer progression-free survival for MRD-negative vs MRD-positive CR patients by NGF (75% progression-free survival not reached vs 7 months; P=0.02). This study establishes EuroFlow-based NGF as a highly sensitive, fully standardized approach for MRD detection in MM which overcomes the major limitations of conventional flow-MRD methods and is ready for implementation in routine diagnostics.

  10. A relationship between salivary flow rates and Candida counts in patients with xerostomia

    Science.gov (United States)

    Nadig, Suchetha Devendrappa; Ashwathappa, Deepak Timmasandra; Manjunath, Muniraju; Krishna, Sowmya; Annaji, Araleri Gopalkrishna; Shivaprakash, Praveen Kunigal

    2017-01-01

    Context: Most of the adult population is colonized by Candida in their oral cavity. The process of colonization depends on several factors, including the interaction between Candida and salivary proteins. Therefore, salivary gland hypofunction may alter the oral microbiota and increase the risk for opportunistic infections, such as candidiasis. Hence, it is necessary to evaluate the relationship between salivary flow rates (SFRs) and Candida colony counts in the saliva of patients with xerostomia. Aims: This study aims to determine and evaluate the relationship between SFRs and Candida colony forming units (CFUs) in patients with xerostomia. Settings and Design: This study was a descriptive study. Subjects and Methods: The study participants were taken from the patients attending outpatient department in a private dental college. Fifty patients, who reported xerostomia in a questionnaire of the symptoms of xerostomia, were selected. Chewing stimulated whole saliva samples were collected from them and their SFRs were assessed. Saliva samples were inoculated in the Sabouraud dextrose agar culture media for 24–48 h, and Candida CFUs were counted. Statistical Analysis Used: Chi-squared test was used to analyze the data. Results: There was a significant inverse relationship between salivary flow and candida CFUs count when patients with high colony counts were analyzed (cutoff point of 400 or greater CFU/mL). Females had less SFR than males. Most of the patients who had hyposalivation were taking medication for the underlying systemic diseases. Candida albicans was the most frequent species. Conclusions: There was a significantly negative correlation between SFRs and Candida CFUs in the patients with xerostomia. PMID:28932047

  11. Engine panel seals for hypersonic engine applications: High temperature leakage assessments and flow modelling

    Science.gov (United States)

    Steinetz, Bruce M.; Mutharasan, Rajakkannu; Du, Guang-Wu; Miller, Jeffrey H.; Ko, Frank

    1992-01-01

    A critical mechanical system in advanced hypersonic engines is the panel-edge seal system that seals gaps between the articulating horizontal engine panels and the adjacent engine splitter walls. Significant advancements in seal technology are required to meet the extreme demands placed on the seals, including the simultaneous requirements of low leakage, conformable, high temperature, high pressure, sliding operation. In this investigation, the seal concept design and development of two new seal classes that show promise of meeting these demands will be presented. These seals include the ceramic wafer seal and the braided ceramic rope seal. Presented are key elements of leakage flow models for each of these seal types. Flow models such as these help designers to predict performance-robbing parasitic losses past the seals, and estimate purge coolant flow rates. Comparisons are made between measured and predicted leakage rates over a wide range of engine simulated temperatures and pressures, showing good agreement.

  12. Flow-Based Systems for Rapid and High-Precision Enzyme Kinetics Studies

    Directory of Open Access Journals (Sweden)

    Supaporn Kradtap Hartwell

    2012-01-01

    Full Text Available Enzyme kinetics studies normally focus on the initial rate of enzymatic reaction. However, the manual operation of steps of the conventional enzyme kinetics method has some drawbacks. Errors can result from the imprecise time control and time necessary for manual changing the reaction cuvettes into and out of the detector. By using the automatic flow-based analytical systems, enzyme kinetics studies can be carried out at real-time initial rate avoiding the potential errors inherent in manual operation. Flow-based systems have been developed to provide rapid, low-volume, and high-precision analyses that effectively replace the many tedious and high volume requirements of conventional wet chemistry analyses. This article presents various arrangements of flow-based techniques and their potential use in future enzyme kinetics applications.

  13. Saliva flow rate, buffer capacity, and pH of autistic individuals.

    Science.gov (United States)

    Bassoukou, Ivy Haralambos; Nicolau, José; dos Santos, Maria Teresa

    2009-03-01

    The objective of the study was to evaluate saliva flow rate, buffer capacity, pH levels, and dental caries experience (DCE) in autistic individuals, comparing the results with a control group (CG). The study was performed on 25 noninstitutionalized autistic boys, divided in two groups. G1 composed of ten children, ages 3-8. G2 composed of 15 adolescents ages 9-13. The CG was composed of 25 healthy boys, randomly selected and also divided in two groups: CG3 composed of 14 children ages 4-8, and CG4 composed of 11 adolescents ages 9-14. Whole saliva was collected under slight suction, and pH and buffer capacity were determined using a digital pHmeter. Buffer capacity was measured by titration using 0.01 N HCl, and the flow rate expressed in ml/min, and the DCE was expressed by decayed, missing, and filled teeth (permanent dentition [DMFT] and primary dentition [dmft]). Data were plotted and submitted to nonparametric (Kruskal-Wallis) and parametric (Student's t test) statistical tests with a significance level less than 0.05. When comparing G1 and CG3, groups did not differ in flow rate, pH levels, buffer capacity, or DMFT. Groups G2 and CG4 differ significantly in pH (p = 0.007) and pHi = 7.0 (p = 0.001), with lower scores for G2. In autistic individuals aged 3-8 and 9-13, medicated or not, there was no significant statistical difference in flow rate, pH, and buffer capacity. The comparison of DCE among autistic children and CG children with deciduous (dmft) and mixed/permanent decayed, missing, and filled teeth (DMFT) did not show statistical difference (p = 0.743). Data suggest that autistic individuals have neither a higher flow rate nor a better buffer capacity. Similar DCE was observed in both groups studied.

  14. Prediction of Leak Flow Rate Using FNNs in Severe LOCA Circumstances

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Yeong; Yoo, Kwae Hwan; Kim, Ju Hyun; Na, Man Gyun [Chosun University, Gwangju (Korea, Republic of); Hur, Seop; Kim, Chang Hwoi [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    Leak flow rate is a function of break size, differential pressure ( i.e., difference between internal and external reactor vessel pressure), temperature, and so on. Specially, the leak flow rate is strongly dependent on the break size and the differential pressure, but the break size is not measured and the integrity of pressure sensors is not assured in severe circumstances. In this study, a fuzzy neural network (FNN) model is proposed to predict the leak flow rate out of break, which has a direct impact on the important times (time approaching the core exit temperature that exceeds 1200 .deg. F, core uncover time, reactor vessel failure time, etc.). Since FNN is a data-based model, it requires data to develop and verify itself. However, because actual severe accident data do not exist to the best of our knowledge, it is essential to obtain the data required in the proposed model using numerical simulations. These data were obtained by simulating severe accident scenarios for the optimized power reactor 1000 (OPR 1000) using MAAP4 code. In this study, FNN model was developed to predict the leak flow rate in severe post-LOCA circumstances.. The training data were selected from among all the acquired data using an SC method to train the proposed FNN model with more informative data. The developed FNN model predicted the leak flow rate using the time elapsed after reactor shutdown and the predicted break size, and its validity was verified in the basis of the simulation data of OPR1000 using MAAP4 code.

  15. Engineering of Biomimetic Hair-Flow Sensor Arrays Dedicated to High-Resolution Flow Field Measurements

    NARCIS (Netherlands)

    Dagamseh, A.M.K.; Bruinink, C.M.; Droogendijk, H.; Wiegerink, Remco J.; Lammerink, Theodorus S.J.; Krijnen, Gijsbertus J.M.

    2010-01-01

    This paper addresses the latest developments in biomimetic hair-flow sensors towards sensitive high-density arrays. Improving the electrodes design of the hair sensor, using Silicon-on-Insulator (SOI) wafer technology, has resulted in the ability to measure small capacitance changes as caused by

  16. High-Flow Nasal Cannula Therapy Versus Intermittent Noninvasive Ventilation in Obese Subjects After Cardiothoracic Surgery.

    Science.gov (United States)

    Stéphan, François; Bérard, Laurence; Rézaiguia-Delclaux, Saida; Amaru, Priscilla

    2017-09-01

    Obese patients are considered at risk of respiratory failure after cardiothoracic surgery. High-flow nasal cannula has demonstrated its non-inferiority after cardiothoracic surgery compared to noninvasive ventilation (NIV), which is the recommended treatment in obese patients. We hypothesized that NIV was superior to high-flow nasal cannula for preventing or resolving acute respiratory failure after cardiothoracic surgery in this population. We performed a post hoc analysis of a randomized, controlled trial. Obese subjects were randomly assigned to receive NIV for at least 4 h/d (inspiratory pressure, 8 cm H2O; expiratory pressure, 4 cm H2O; FIO2 , 0.5) or high-flow nasal cannula delivered continuously (flow, 50 L/min, FIO2 0.5). Treatment failure (defined as re-intubation, switch to the other treatment, or premature discontinuation) occurred in 21 of 136 (15.4%, 95% CI 9.8-22.6%) subjects with NIV compared to 18 of 135 (13.3%, 95% CI 8.1-20.3%) subjects with high-flow nasal cannula (P = .62). No significant differences were found for dyspnea and comfort scores. Skin breakdown was significantly more common with NIV after 24 h (9.2%, 95% CI 5.0-16.0 vs 1.6%, 95% CI 1.0-6.0; P = .01). No significant differences were found for ICU mortality (5.9% for subjects with NIV vs 2.2% for subjects with high-flow nasal cannula, P = .22) or for any of the other secondary outcomes. Among obese cardiothoracic surgery subjects with or without respiratory failure, the use of continuous high-flow nasal cannula compared to intermittent NIV (8/4 cm H2O) did not result in a worse rate of treatment failure. Because high-flow nasal cannula presents some advantages, it may be used instead of NIV in obese patients after cardiothoracic surgery. Copyright © 2017 by Daedalus Enterprises.

  17. Properties of thin films for high temperature flow sensors

    Science.gov (United States)

    Albin, Sacharia

    1991-01-01

    Requirements of material parameters of high temperature flow sensors are identified. Refractory metal silicides offer high temperature sensitivity and high frequency response and are stable up to 1000 C. Intrinsic semiconductors of high band gap are also considered as sensor elements. SiC and diamond are identified. Combined with substrates of low thermal and electrical conductivity, such as quartz or Al2O3, these materials meet several requirements of high sensitivity and frequency response. Film deposition and patterning techniques suitable for these materials are identified.

  18. Comparison of Aerodynamic Particle Size Distribution Between a Next Generation Impactor and a Cascade Impactor at a Range of Flow Rates.

    Science.gov (United States)

    Yoshida, Hiroyuki; Kuwana, Akemi; Shibata, Hiroko; Izutsu, Ken-Ichi; Goda, Yukihiro

    2017-04-01

    Wide variation in respiratory flow rates between patients emphasizes the importance of evaluating the aerodynamic particle size distribution (APSD) of dry powder inhaler (DPI) using a multi-stage impactor at different flow rates. US Pharmacopeia recently listed modified configurations of the Andersen cascade impactor (ACI) and new sets of cut-off diameter specifications for the operation at flow rates of 60 and 90 L/min. The purpose of this study was to clarify the effect of these changes on the APSD of DPI products at varied flow rates. We obtained APSD profiles of four DPIs and device combinations, Relenza®-Diskhaler® (GlaxoSmithKline Co.), Seebri®-Breezhaler® (Novartis Pharma Co.), Pulmicort®-Turbuhaler® (Astrazeneca Co.), and Spiriva®-Handihaler® (Nippon Boehringer Ingelheim Co.) using Next Generation Impactors (NGIs) and ACIs at flow rates from 28.3 to 90 L/min to evaluate the difference in the use of previous and new sets of cut-off diameter specifications. Processing the data using the new specifications for ACI apparently reduced large differences in APSD obtained by NGI and ACI with the previous specifications at low and high flow rates in all the DPIs. Selecting the appropriate configuration of ACI corresponding to the flow rate provided comparable APSD profiles of Pulmicort®-Turbuhaler® to those using NGIs at varied flow rates. The results confirmed the relevance of the current US Pharmacopeia specifications for ACI analysis in obtaining APSD profiles of DPI products at wide flow rates.

  19. The association between coronary flow rate and impaired heart rate recovery in patients with metabolic syndrome: A preliminary report.

    Science.gov (United States)

    Alihanoglu, Yusuf I; Kilic, I Dogu; Evrengul, Harun; Yildiz, Bekir S; Alur, Ihsan; Uludag, Burcu; Kuru, Omur; Taskoylu, Ozgur; Kaftan, Havane Asuman

    2014-01-01

    The aim of this study is to evaluate heart rate recovery (HRR) and association between coronary flow rate and HRR in patients with metabolic syndrome (MS) who had morphologically normal coronary angiogram. Study population included 43 patients with MS and 37 control subjects without MS. All patients were selected from individuals who had recently undergone coronary angiography in our hospital and were diagnosed as having angiographically normal coronary arteries. Exercise stress test results obtained prior to coronary angiography were evaluated for calculating HRR and other parameters. In addition, coronary flow was objectively evaluated for each major coronary artery in each subject using TIMI frame count method. All HRR values calculated were detected significantly lower in MS group compared to controls (HRR first: 32 ± 9 vs. 37 ± 10; p = 0.01, second: 46 ± 11 vs. 52 ± 11; p = 0.03, third: 51 ± 12 vs. 59 ± 12; p = 0.00, fourth: 54 ± 13 vs. 61 ± 2; p = 0.02). TIMI frame counts for each major epicardial coronary artery and mean TIMI frame count were also found to be significantly higher in MS group compared to controls (left anterior descending artery:51 ± 24 vs. 39 ± 15; p = 0.009, left circumflex artery: 32 ± 11 vs. 24 ± 7; p = 0.001, right coronary artery: 33 ± 14 vs. 24 ± 10; p = 0.003, mean TIMI frame count: 38 ± 15 vs. 29 ± 9;p = 0.002). Additionally, significant negative correlations were also detected between HRR first minute and coronary TIMI frame count values in patients with MS. None of MS parameters did not affect HRR values, however mean TIMI frame count independently associated with HRR first minute (p = 0.04) in patients with MS. Impaired coronary blood flow occurring in MS might be a clue of autonomic dysfunction in addition to previously known endothelial dysfunction.

  20. High throughput holographic imaging-in-flow for the analysis of a wide plankton size range.

    Science.gov (United States)

    Yourassowsky, Catherine; Dubois, Frank

    2014-03-24

    We developed a Digital Holographic Microscope (DHM) working with a partial coherent source specifically adapted to perform high throughput recording of holograms of plankton organisms in-flow, in a size range of 3 µm-300 µm, which is of importance for this kind of applications. This wide size range is achieved with the same flow cell and with the same microscope magnification. The DHM configuration combines a high magnification with a large field of view and provides high-resolution intensity and quantitative phase images refocusing on high sample flow rate. Specific algorithms were developed to detect and extract automatically the particles and organisms present in the samples in order to build holograms of each one that are used for holographic refocusing and quantitative phase contrast imaging. Experimental results are shown and discussed.

  1. Influence of peak inspiratory flow rates and pressure drops on inhalation performance of dry powder inhalers.

    Science.gov (United States)

    Hira, Daiki; Okuda, Tomoyuki; Ichihashi, Mika; Mizutani, Ayano; Ishizeki, Kazunori; Okada, Toyoko; Okamoto, Hirokazu

    2012-01-01

    The aim of this study was to reveal the relationship between human inspiratory flow patterns and the concomitant drops in pressure in different inhalation devices, and the influence of the devices on inhalation performance. As a model formulation for inhalers, a physically mixed dry powder composed of salbutamol sulfate and coarse lactose monohydrate was selected. The drops in pressure at 28.3 L/min of three inhalation devices, Single-type, Dual-type, and Reverse-type, was 1.0, 5.1, and 8.7 kPa, respectively. Measurements of human inspiratory patterns revealed that although the least resistant device (Single) had large inter- and intra-individual variation of peak flow rate (PFR), the coefficients of variation of PFR of the three devices were almost the same. In tests with a human inspiratory flow simulator in vitro, inhalation performance was higher, but the variation in inhalation performance in the range of human flow patterns was wider, for the more resistant device. To minimize the intra- and inter-individual variation in inhalation performance for the model formulation in this study, a formulation design that allows active pharmaceutical ingredient to detach from the carrier with a lower inhalation flow rate is needed.

  2. Effect of solar chimney inclination angle on space flow pattern and ventilation rate

    Energy Technology Data Exchange (ETDEWEB)

    Bassiouny, Ramadan; Korah, Nader S.A. [Department of Mechanical Power Engineering and Energy, Minia University, Minia 61111 (Egypt)

    2009-02-15

    The solar chimney is a simple and practical idea that is applied to enhance space natural ventilation. The chimney could be vertical or inclined. The chimney inclination angle is an important parameter that greatly affects space flow pattern and ventilation rate. In the present study, the effect of chimney inclination angle on air change per hour and indoor flow pattern was numerically and analytically investigated. A numerical simulation using Ansys, a FEM-based code, was used to predict flow pattern. Then the results were compared with published experimental measurements. A FORTRAN program was developed to iteratively solve the mathematical model that was obtained through an overall energy balance on the solar chimney. The analytical results showed that an optimum air flow rate value was achieved when the chimney inclination is between 45 and 70 for latitude of 28.4 . The numerically predicted flow pattern inside the space supports this finding. Moreover, in the present study a correlation to predict the air change per hour was developed. The correlation was tested within a solar intensity greater than or equal to 500 W/m{sup 2}, and chimney width from 0.1 m to 0.35 m for different inclination angles with acceptable values. (author)

  3. Uncertainty in future high flows in Qiantang River Basin, China

    NARCIS (Netherlands)

    Tian, Y.; Booij, Martijn J.; Wang, G.

    2015-01-01

    Uncertainties in high flows originating from greenhouse gas emissions scenarios, hydrological model structures, and their parameters for the Jinhua River basin, China, were assessed. The baseline (1961–90) and future (2011–40) climates for A1B, A2, and B2 scenarios were downscaled from the general

  4. Abnormal blood flow in the sublingual microcirculation at high altitude

    NARCIS (Netherlands)

    Martin, Daniel S.; Ince, Can; Goedhart, Peter; Levett, Denny Z. H.; Grocott, Mike P. W.

    2009-01-01

    We report the first direct observations of deranged microcirculatory blood flow at high altitude, using sidestream dark-field imaging. Images of the sublingual microcirculation were obtained from a group of 12 volunteers during a climbing expedition to Cho Oyu (8,201 m) in the Himalayas.

  5. Numerical investigation of high pressure condensing flows in supersonic nozzles

    NARCIS (Netherlands)

    Azzini, L.; Pini, M.

    2017-01-01

    High-pressure non-equilibrium condensing flows are investigated in this paper through a quasi-1D Euler model coupled to the method of moments for the physical characterization of the dispersed phase. Two different numerical approaches, namely the so-called (a) the mixture and (b) continuum phase

  6. Effect of different carrier gases and their flow rates on the growth of carbon nanotubes

    Science.gov (United States)

    Tewari, Aarti; Sharma, Suresh C.

    2015-04-01

    The present paper examines the effect of different carrier gases and their flow rates on the growth of carbon nanotubes (CNTs). A theoretical model is developed incorporating the charging rate of the carbon nanotube, kinetics of all the plasma species, and the growth rate of the CNTs because of diffusion and accretion of ions on the catalyst nanoparticle. The three different carrier gases, i.e., argon (Ar), ammonia, and nitrogen, are considered in the present investigation, and flow rates of all the three carrier gases are varied individually (keeping the flow rates of hydrocarbon and hydrogen gas constant) to investigate the variations in the number densities of hydrocarbon and hydrogen ions in the plasma and their consequent effects on the height and radius of CNT. Based on the results obtained, it is concluded that Ar favors the formation of CNTs with larger height and radius whereas ammonia contributes to better height of CNT but decreases the radius of CNT, and nitrogen impedes both the height and radius of CNT. The present work can serve to the better understanding of process parameters during growth of CNTs by a plasma enhanced chemical vapor deposition process.

  7. Effects of flow and water chemistry on lead release rates from pipe scales.

    Science.gov (United States)

    Xie, Yanjiao; Giammar, Daniel E

    2011-12-01

    Lead release from pipe scales was investigated under different water compositions, stagnation times, and flow regimes. Pipe scales containing PbO(2) and hydrocerussite (Pb(3)(OH)(2)(CO(3))(2)) were developed on lead pipes by conditioning the pipes with water containing free chlorine for eight months. Water chemistry and the composition of the pipe scales are two key factors affecting lead release from pipe scales. The water rarely reached equilibrium with pipe scales within one day, which makes solid-water contact time and corrosion product dissolution rates the controlling factors of lead concentrations for the conditions tested. Among five water compositions studied, a solution with orthophosphate had the lowest dissolved lead release rate and highest particulate lead release rate. Free chlorine also decreased the dissolved lead release rate at stagnant conditions. Water flow increased rates of release of both dissolved and particulate lead by accelerating the mass transfer of lead out of the porous pipe scales and by physically destabilizing pipe scales. Dissolved lead comprised the majority of the lead released at both stagnant and laminar flow conditions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Stability of unstimulated and stimulated whole saliva flow rates in children.

    Science.gov (United States)

    Sánchez-Pérez, Leonor; Irigoyen-Camacho, Esther; Sáenz-Martínez, Laura; Zepeda Zepeda, Marco; Acosta-Gío, Enrique; Méndez-Ramírez, Ignacio

    2016-09-01

    To analyze the stability of the unstimulated saliva flow rate (USFR) and the stimulated saliva flow rate (SSFR) in children followed from age 7 to 12 years old. Longitudinal study. Whole saliva samples were collected from school children (50 girls and 50 boys). Forty-four girls and 32 boys remained in this cohort for 6 years (dropout rate 24%). Variables that could influence USFR or SSFR patterns were analyzed in a repeated-measures manova. Over a 6-year follow-up, the children's USFR ranged from 0.41 to 0.46 mL/min in the initial and final observation, respectively, and showed no significant differences (P = 0.4455) during the follow-up. The children consistently belonged to one of three distinct SSFR groups (P saliva for screening or diagnostic purposes. © 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. High PRF ultrafast sliding compound doppler imaging: fully qualitative and quantitative analysis of blood flow.

    Science.gov (United States)

    Kang, Jinbum; Jang, Won Seuk; Yoo, Yangmo

    2018-01-15

    Ultrafast compound Doppler imaging based on plane-wave excitation (UCDI) can be used to evaluate cardiovascular diseases using high frame rates. In particular, it provides a fully quantifiable flow analysis over a large region of interest with high spatio-temporal resolution. However, the pulse-repetition frequency (PRF) in the UCDI method is limited for high-velocity flow imaging since it leverages between the number of plane-wave angles (N) and acquisition time. In this paper, we present high PRF ultrafast sliding compound Doppler imaging method (HUSDI) to improve quantitative flow analysis. With the HUSDI method, full scanline images (i.e., each tilted plane wave data) in a Doppler frame buffer are consecutively summed using a sliding window to create high-quality ensemble data so that there is no reduction in frame rate and flow sensitivity. In addition, by updating a new compounding set with a certain time difference (i.e., sliding window step size or L), the HUSDI method allows various Doppler PRFs with the same acquisition data to enable a fully qualitative, retrospective flow assessment. To evaluate the performance of the proposed HUSDI method, simulation, in vitro and in vivo studies were conducted under diverse flow circumstances. In the simulation and in vitro studies, the HUSDI method showed improved hemodynamic representations without reducing either temporal resolution or sensitivity compared to the UCDI method. For the quantitative analysis, the root mean squared velocity error (RMSVE) was measured using 9 angles (-12° to 12°) with L of 1 to 9, and the results were found to be comparable to those of the UCDI method (L=N=9), i.e., ≤ 0.24 cm/s, for all L values. For the in vivo study, the flow data acquired from a full cardiac cycle of the femoral vessels of a healthy volunteer were analyzed using a PW spectrogram, and arterial and venous flows were successfully assessed with

  10. Relative viscosity of emulsions in simple shear flow: Temperature, shear rate, and interfacial tension dependence

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Se Bin; Lee, Joon Sang [Dept. of Mechanical Engineering, Yonsei Unversity, Seoul (Korea, Republic of)

    2015-08-15

    We simulate an emulsion system under simple shear rates to analyze its rheological characteristics using the lattice Boltzmann method (LBM). We calculate the relative viscosity of an emulsion under a simple shear flow along with changes in temperature, shear rate, and surfactant concentration. The relative viscosity of emulsions decreased with an increase in temperature. We observed the shear-thinning phenomena, which is responsible for the inverse proportion between the shear rate and viscosity. An increase in the interfacial tension caused a decrease in the relative viscosity of the decane-in-water emulsion because the increased deformation caused by the decreased interfacial tension significantly influenced the wall shear stress.

  11. Accurate measurements of experimental parameters in supercritical fluid chromatography. I. Extent of variations of the mass and volumetric flow rates.

    Science.gov (United States)

    Tarafder, Abhijit; Guiochon, Georges

    2013-04-12

    Previous reports have highlighted the influence of the properties of the mobile phase flow rate on the column performance achieved in supercritical fluid chromatography (SFC). In SFC both the mass and the volumetric flow rates have unique influences on the chromatographic performance and the determination of their exact values is critical. It is well understood that the mass flow rate stays constant along an SFC system whereas the volumetric flow rate may vary considerably, but the extent of these variations and the role of the individual operating parameters in influencing these variations have not been clearly reported yet. The factors that control the mass and the volumetric flow rates in an SFC system are discussed and the possible extent of variations of these flow rates under different operating pressures and temperatures are demonstrate quantitatively. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Comparison of emergence times with different fresh gas flow rates following desflurane anaesthesia.

    Science.gov (United States)

    Jeong, Ji Seon; Yoon, Sung Wook; Choi, Sung Lark; Choi, Sung Hwan; Lee, Bong Yeong; Jeong, Mi Ae

    2014-12-01

    To investigate emergence times with different fresh gas flow rates, following desflurane anaesthesia. Patients undergoing surgery with desflurane anaesthesia were randomly assigned to receive fresh gas flow rates of 100% oxygen during emergence of 2 l/min (group D2), 4 l/min (group D4) or 6 l/min (group D6). Time to eye opening, spontaneous movement and extubation (emergence time) were assessed after desflurane discontinuation. The end-tidal concentration of desflurane and bispectral index were recorded at each of these timepoints. A total of 105 patients were included in the study, with 35 in each of the three groups. Mean times to extubation were 17.6 min, 9.9 min and 9.1 min in groups D2, D4 and D6, respectively. Times to eye opening, spontaneous movement and extubation in group D2 were significantly longer than in groups D4 and D6. These results suggest that there is the potential to predict emergence time based on fresh gas flow rate following desflurane anaesthesia. It should therefore be possible to use a low-flow technique during the emergence period, in addition to the maintenance period, without delaying recovery if the inhaled anaesthetic is stopped at the predicted time before the end of surgery. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  13. Long-term flow-through column experiments and their relevance to natural granitoid weathering rates

    Science.gov (United States)

    White, Arthur F.; Schulz, Marjorie S.; Lawrence, Corey R.; Vivit, Davison V.; Stonestrom, David A.

    2017-01-01

    Four pairs of fresh and partly-weathered granitoids, obtained from well-characterized watersheds—Merced River, CA, USA; Panola, GA, USA; Loch Vale, CO, USA, and Rio Icacos, Puerto Rico—were reacted in columns under ambient laboratory conditions for 13.8 yrs, the longest running experimental weathering study to date. Low total column mass losses (flow rates. Effluent Na concentrations showed no clear trend with time during the last decade of reaction (fresh granitoids) or increased slowly with time (weathered granitoids). Analysis of cumulative Na release indicated that plagioclase dissolution achieved steady state in 3 of the 4 fresh granitoids during the last decade of reaction. Surface-area normalized plagioclase dissolution rates exhibited a narrow range (0.95 to 1.26 10-13 moles m-2 s-1), in spite of significant stoichiometric differences (An0.21 to An0.50). Rates were an order of magnitude slower than previously reported in shorter duration experiments but generally 2 to 3 orders of magnitude faster than corresponding natural analogs. CrunchFlow simulations indicated that more than a hundredfold decrease in column flow rates would be required to produce near-saturation reaction affinities that would start to slow plagioclase weathering to real-world levels. Extending simulations to approximate long term weathering in naturally weathered profiles required additional decreases in the intrinsic plagioclase dissolution and kaolinite precipitation rates and relatively large decreases in the fluid flow rate, implying that exposure to reactive mineral surfaces is significantly limited in the natural environment compared to column experiments.

  14. Liquid-phase reduction synthesis of mono-dispersed gold nanoparticles on glass microfluidic device with flow rate control

    Science.gov (United States)

    Tanabe, Yu; Yagyu, Hiromasa

    2017-02-01

    Gold nanoparticles (GNPs) in aqueous dispersion were synthesized on a low-cost glass microfluidic device developed by authors. The effect of a channel width and a flow rate on the size distribution of synthesized GNPs was reported for synthesis of mono-dispersed GNPs. A soda-lime glass substrates was processed by the micropowder blasting. Three holes were processed on the upper substrate, and Y-shaped microchannel was processed on the bottom substrate. Tetrachloroauric (III) acid aqueous solution for Au ion and the mixture of aqueous solution of sodium citrate acid for reducing agent and tannic acid for the protective agent were injected to a microchannel in the device by syringe pump. From the analysis of absorption peak at around 530nm in absorption spectrum, the synthesized GNPs on the device has sharpen peak in comparison with that of GNPs synthesized on the beaker. Moreover, the spectrum with low flow rate showed a sharpened peak in comparison with that of high rate. In the channel width of 260μm, the full width at half maximum (FWHM) at the absorption peak affecting to a distribution of diameter of GNPs were 79.2nm for 0.05mL/min and 92.9nm for 0.06mL/min. Conversely, FWHM in the channel width of 430μm showed almost constant value. From TEM images, the synthesized GNPs using the channel width of 260μm at the flow rate of 0.05mL/min was found to have the mean diameter of 11.5nm and coefficient of variation of 0.09. These results confirmed that the combination of low flow rate and small channel width were attributed to realizing the mono-dispersed GNPs.

  15. Real exchange rate, trade flows and foreign direct investments: the Moroccan case

    OpenAIRE

    Bouoiyour, Jamal; Rey, Serge

    2005-01-01

    We study the behavior of the Real Effective Exchange Rate (REER) of the dirham against the European currencies (the EU15), over the period 1960–2000. We measure the volatility using standard deviation, and the misalignments as the difference between the actual REER and the equilibrium REER (NATREX model). We show that a rise in the volatility of the dirham reduces the trade flows, i.e. the exports and the imports. The misalignments also affect the trade flows: an overvaluation leads to a redu...

  16. Venturi fouling and what can cause an overestimate of the flow rate by one percent

    Energy Technology Data Exchange (ETDEWEB)

    Hedberg, P. [Remote CAE AB, Gothenburg (Sweden); Nilsson, H. [Ringhals AB, Varobacka (Sweden)

    2011-07-01

    In this study, we are looking for phenomena which can explain the effect that venturi fouling has on the measurement of feedwater flow rate in a PWR, Unit 3 of Ringhals Nuclear Power Plant, Sweden. When hydrazine is injected into the feedwater, it reduces the deposits of magnetite on the wetted surface of the venturi, and elsewhere at the given temperature ~200°C. This changes the reading from the flow measuring device and becomes closer to the originally calibrated data. Over time magnetite is rebuilt on the walls. We are searching for what can overestimate the mass flow rate in the order of 1%. Potential explanations are; changes in the venturi cross section area, change in properties of the fluid mixture, effects of suspended magnetite particles, changes in wall shear stress due to regular wall roughness, changes in the wall shear stress due to self-organized ripple wall roughness, changes in swirling flow due to wall roughness, separation in the diffuser part of venturi due to wall roughness, changes in the velocity profile (entering the venturi) due to wall roughness, and local buildup of deposits around the pressure taps. Besides visual inspection of recently replaced venturi meters, numerical and theoretical estimates have been used to find the most likely explanation. We have derived a new wall function to introduce the self-organized ripple wall shear stress and used it in CFD (Computational Fluid Dynamics) simulations. The first conclusion from the simulations is that the required regular wall roughness is not consistent with the observed thickness of the deposit on the wetted surfaces. Nor does the cross section area change sufficiently to make the flow rate deviate by 1%. The changes in fluid properties, due to the fluid mixing, are not significant. This is also true for a fluid with suspended magnetite particles. The only effect that is large enough to overestimate the flow by 1% is the self-organized wall ripple, for the observed deposit thickness

  17. The efficacy of oxygen wafting using different delivery devices, flow rates and device positioning.

    Science.gov (United States)

    Blake, Denise F; Shih, Elizabeth M; Mateos, Paul; Brown, Lawrence H

    2014-08-01

    Oxygen "wafting" provides a non-contact oxygen alternative for uncooperative paediatric patients in the emergency department (ED). The aim of this study was to identify the combination of oxygen delivery device, flow rate and device positioning that delivers the highest concentration of wafted oxygen. ED nursing staff were surveyed to determine current oxygen wafting practice. A simulated patient and oxygen sensor were used to compare wafted oxygen concentrations for six delivery devices in various positions and oxygen flow rates. Only oxygen tubing and the paediatric non-rebreather mask consistently delivered wafted oxygen concentrations above 30%. The paediatric non-rebreather held below the face produced concentrations ranging from 26.1% (10 cm) to 39.8% (5 cm). At 15 L/min, tubing held in front of the face produced concentrations ranging from 31.2% (15 cm) to 56.7% (5 cm); reducing the flow rate to 6-8 L/min had no meaningful effect on the delivered oxygen concentration. When tubing was used below the face, flow rates between 6 and 8 L/min produced somewhat higher concentrations than 15 L/min (5 cm: 36.3% vs. 30.9%). When delivering oxygen by wafting, the highest oxygen concentrations are achieved when positioning tubing 5-15 cm in front of the face or positioning tubing or a paediatric non-rebreather mask 5-10 cm below the face at 10-15 L/min flow. This should be considered when using oxygen wafting in the ED. Copyright © 2014 College of Emergency Nursing Australasia Ltd. Published by Elsevier Ltd. All rights reserved.

  18. Modeling the influence of preferential flow on the spatial variability and time-dependence of mineral weathering rates

    Science.gov (United States)

    Pandey, Sachin; Rajaram, Harihar

    2016-12-01

    Inferences of weathering rates from laboratory and field observations suggest significant scale and time-dependence. Preferential flow induced by heterogeneity (manifest as permeability variations or discrete fractures) has been suggested as one potential mechanism causing scale/time-dependence. We present a quantitative evaluation of the influence of preferential flow on weathering rates using reactive transport modeling. Simulations were performed in discrete fracture networks (DFNs) and correlated random permeability fields (CRPFs), and compared to simulations in homogeneous permeability fields. The simulations reveal spatial variability in the weathering rate, multidimensional distribution of reactions zones, and the formation of rough weathering interfaces and corestones due to preferential flow. In the homogeneous fields and CRPFs, the domain-averaged weathering rate is initially constant as long as the weathering front is contained within the domain, reflecting equilibrium-controlled behavior. The behavior in the CRPFs was influenced by macrodispersion, with more spread-out weathering profiles, an earlier departure from the initial constant rate and longer persistence of weathering. DFN simulations exhibited a sustained time-dependence resulting from the formation of diffusion-controlled weathering fronts in matrix blocks, which is consistent with the shrinking core mechanism. A significant decrease in the domain-averaged weathering rate is evident despite high remaining mineral volume fractions, but the decline does not follow a 1/t dependence, characteristic of diffusion, due to network scale effects and advection-controlled behavior near the inflow boundary. The DFN simulations also reveal relatively constant horizontally averaged weathering rates over a significant depth range, challenging the very notion of a weathering front.

  19. Miniature High Stability High Temperature Space Rated Blackbody Radiance Source

    Science.gov (United States)

    Jones, J. A.; Beswick, A. G.

    1987-09-01

    This paper presents the design and test performance of a conical cavity type blackbody radiance source that will meet the requirements of the Halogen Occultation Experiment (HALOE) on the NASA Upper Atmospheric Research Satellite program (UARS). Since a radiance source meeting the requirements of this experiment was unavailable in the commercial market, a development effort was undertaken by the HALOE Project. The blackbody radiance source operates in vacuum at 1300 K + 0.5 K over any 15-minute interval, uses less than 7.5 watts of power, maintains a 49°C outer case temperature, and fits within the 2.5 x 2.5 x 3.0 inch envelope allocated inside the HALOE instrument. Also, the unit operates in air, during ground testing of the HALOE instrument, where it uses 17 watts of power with an outer case temperature of 66°C. The thrust of this design effort was to minimize the heat losses, in order to keep the power usage under 7.5 watts, and to minimize the amount of silica in the materials. Silica in the presence of the platinum heater winding used in this design would cause the platinum to erode, changing the operating temperature set-point. The design required the development of fabrication techniques which would provide very small, close tolerance parts from extremely difficult-to-machine materials. Also, a space rated ceramic core and unique, low thermal conductance, ceramic-to-metal joint was developed, tested and incorporated in this design. The completed flight qualification hardware has undergone performance, environmental and life testing. The design configuration and test results are discussed in detail in this paper.

  20. On the consistency of flow rate color Doppler assessment for the internal jugular vein

    Directory of Open Access Journals (Sweden)

    Francesco Sisini

    2014-01-01

    Full Text Available Color Doppler methodology to assess the vessel blood flow rate is based on the time averaged velocity of the blood measured in the longitudinal plane and the cross sectional area measurement taken either in the longitudinal plane, by assuming circular cross sectional area, or in the transversal plane. The measurement option in longitudinal plane is based on the assumption of circular cross sectional area, while the transversal one needs to evaluate both time-averaged velocity and cross sectional area in the same vessel point. A precise and validated assessment methodology is still lacking. Four healthy volunteers underwent internal jugular vein colour Doppler scanning. The cross sectional area was assessed by means of B-mode imaging in the transversal plane all along the vessel cervical course. During this assessment, cross sectional area, major and minor axis of the vessel were measured and recorded. The distance between the internal jugular vein wall and the skin surface were measured together with the intra-luminal diameter and statistically correlated with the cross sectional area data. The internal jugular vein cross sectional area measured on the transversal plane were significantly different from the cross sectional area calculated using the assumption of circular shape. The intra-luminal distance showed high correlation with the measured cross sectional area. The proper anatomical point in the cross sectional area transversal measurement can be identified by using the internal jugular vein intra-luminal distance as landmark.

  1. In vivo imaging of ocular blood flow using high-speed ultrasound

    Science.gov (United States)

    Ketterling, Jeffrey A.; Urs, Raksha; Silverman, Ronald H.

    2017-01-01

    Clinical ophthalmic ultrasound is currently performed with mechanically scanned, single-element probes, but these are unable to provide useful information about blood flow with Doppler techniques. Linear arrays are well-suited for the detection of blood flow, but commercial systems generally exceed FDA ophthalmic safety limits. A high-speed plane-wave ultrasound approach with an 18-MHz linear array was utilized to characterize blood flow in the orbit and choroid. Acoustic intensity was measured and the plane-wave mode was within FDA limits. Data were acquired for up to 2 sec and up to 20,000 frames/s with sets of steered plane-wave transmissions that spanned 2*θ degrees where 0 degrees was normal to the array. Lateral resolution was characterized using compounding from 1 to 50 transmissions and -6-dB lateral beamwidths ranged from 320 to 180 μm, respectively. Compounded high-frame-rate data were post-processed using a singular value decomposition spatiotemporal filter and then flow was estimated at each pixel using standard Doppler processing methods. A 1-cm diameter rotating scattering phantom and a 2-mm diameter tube with a flow of blood-mimicking fluid were utilized to validate the flow-estimation algorithms. In vivo data were obtained from the posterior pole of the human eye which revealed regions of flow in the choroid and major orbital vessels supplying the eye. PMID:28275423

  2. Modeling the interaction between flow and highly flexible aquatic vegetation

    Science.gov (United States)

    Dijkstra, J. T.; Uittenbogaard, R. E.

    2010-12-01

    Aquatic vegetation has an important role in estuaries and rivers by acting as bed stabilizer, filter, food source, and nursing area. However, macrophyte populations worldwide are under high anthropogenic pressure. Protection and restoration efforts will benefit from more insight into the interaction between vegetation, currents, waves, and sediment transport. Most aquatic plants are very flexible, implying that their shape and hence their drag and turbulence production depend on the flow conditions. We have developed a numerical simulation model that describes this dynamic interaction between very flexible vegetation and a time-varying flow, using the sea grass Zostera marina as an example. The model consists of two parts: an existing 1DV k-ɛ turbulence model simulating the flow combined with a new model simulating the bending of the plants, based on a force balance that takes account of both vegetation position and buoyancy. We validated this model using observations of positions of flexible plastic strips and of the forces they are subjected to, as well as hydrodynamic measurements. The model predicts important properties like the forces on plants, flow velocity profiles, and turbulence characteristics well. Although the validation data are limited, the results are sufficiently encouraging to consider our model to be of generic value in studying flow processes in fields of flexible vegetation.

  3. Kinetic behaviour in supercritical fluid chromatography with modified mobile phase for 5 μm particle size and varied flow rates.

    Science.gov (United States)

    Lesellier, E; Fougere, L; Poe, Donald P

    2011-04-15

    After much development of stationary phase chemistry, in recent years the focus of many studies in HPLC has shifted to increase the efficiency and analysis speed. Ultra high pressure liquid chromatography (UHPLC) using sub-2 μm particles, and high temperature liquid chromatography (HTLC), using temperatures above 100°C have received much attention. These new approaches allow the use of flow rates higher than those classically used in HPLC, reducing the analysis duration. Due to the low viscosity of supercritical fluids, high velocities, i.e. high flow rates, can be achieved with classical pumping systems typically used in supercritical fluid chromatography (SFC). The effects of the flow rate increase with CO(2)/methanol mobile phase was studied on the inlet pressure, t(0), the retention factor of the compounds, and on the efficiency. Simple comparisons of efficiencies obtained at varied temperature between SFC and HPLC, with a packed column containing 5 μm particles, show the greater kinetic performances achieved with the CO(2)/methanol fluid, and underline specific behaviours of SFC, occurring for high flow rates and sub-ambient temperature. Some values (N/t(0)) are also compared to UHPLC data, showing that good performance can be achieved in SFC without applying drastic analytical conditions. Finally, simple kinetic plots (t(0) vs N) at constant column length are used to select combinations of temperature and flow rate necessary to achieve a required theoretical plate number. Copyright © 2010 Elsevier B.V. All rights reserved.

  4. Flow rate, syringe size and architecture are critical to start-up performance of syringe pumps.

    Science.gov (United States)

    Neff, S B; Neff, T A; Gerber, S; Weiss, M M

    2007-07-01

    Significant start-up delays are inherent to syringe infusion pumps, particularly at low infusion rates, as routinely used in children's anaesthesia and intensive care. Such delays are mainly the result of engagement of gears in the mechanical drive or compliance of the syringe assembly. The purpose of the present study was to determine the effect of flow rate, syringe size and syringe architecture on fluid delivery during infusion start-up. Elapsed time from infusion start to achievement of steady-state flow was gravimetrically determined for various infusion rates (0.1, 0.5, 1 mL h-1), different syringe sizes (10-, 20-, 30-, 50-mL) and syringes of two different brands (BD and Codan). Four measurements for each condition were performed with two identical Alaris Asena GH syringe infusion pumps (total of eight experiments). Statistical analysis was done by two-way ANOVA with Bonferroni's post-test; P brand in comparison with the Codan syringes (P < 0.01). Highest possible flow rate, smaller sized syringes and syringe plungers with reduced compressibility should be preferred in order to avoid significant start-up delays in fluid delivery.

  5. Primary standard for liquid flow rates between 30 and 1500 nl/min based on volume expansion.

    Science.gov (United States)

    Lucas, Peter; Ahrens, Martin; Geršl, Jan; Sparreboom, Wouter; Lötters, Joost

    2015-08-01

    An increasing number of microfluidic systems operate at flow rates below 1 μl/min. Applications include (implanted) micropumps for drug delivery, liquid chromatography, and microreactors. For the applications where the absolute accuracy is important, a proper calibration is required. However, with standard calibration facilities, flow rate calibrations below ~1 μl/min are not feasible because of a too large calibration uncertainty. In the current research, a traceable flow rate using a certain temperature increase rate is proposed. When the fluid properties, starting mass, and temperature increase rate are known, this principle yields a direct link to SI units, which makes it a primary standard. In this article, it will be shown that this principle enables flow rate uncertainties in the order of 2-3% for flow rates from 30 to 1500 nl/min.

  6. Sulfate Reduction at pH 5 in a High-Rate Membrane Bioreactor: Reactor Performance and Microbial Community Analyses

    NARCIS (Netherlands)

    Bijmans, M.F.M.; Dopson, M.; Peeters, T.W.T.; Lens, P.N.L.; Buisman, C.J.N.

    2009-01-01

    High rate sulfate reduction under acidic conditions opens possibilities for new process flow sheets that allow the selective recovery of metals from mining and metallurgical waste and process water. However, knowledge about high-rate sulfate reduction under acidic conditions is limited. This paper

  7. Emergence and decay rate of the edge plasma flow shear near a critical transition

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, J M; Garcia, L [Universidad Carlos III, 28911 Leganes, Madrid (Spain); Carreras, B A [BACV Solutions, Inc, Oak Ridge, Tennessee 37830 (United States)], E-mail: jmdelgad@fis.uc3m.es

    2009-01-15

    Recently, the experimental results for the emergence of the plasma shear flow layer in TJ-II have been explained as a second-order phase transition like process by using a simple model of envelope equations for the fluctuation level, the averaged poloidal velocity shear and the pressure gradient (2006 Phys. Plasmas 13 122509). Here, we extend this model by incorporating radial coupling. The model is applied to the study of the turbulence-shear flow interaction when the energy flux is low. Transition dynamics and their concomitant thresholds are examined within the context of this model. The effect of an external torque induced by electrode biasing has also been considered. In particular, we analyze the decay rate of the shear flow after switching off the biasing.

  8. Maximum two-phase flow rates of subcooled nitrogen through a sharp-edged orifice

    Science.gov (United States)

    Simoneau, R. J.

    1975-01-01

    An experiment was conducted and data are presented in which subcooled liquid nitrogen was discharged through a sharp-edged orifice at flow rates near the maximum. The data covered a range of inlet stagnation pressure from slightly above saturation to twice the thermodynamic critical pressure. The data were taken along five separate inlet stagnation isotherms ranging from 0.75 to 1.035 times the thermodynamic critical temperature. The results indicate that: (1) subcooled liquids do not choke or approach maximum flow in an asymptotic manner even though the back pressure is well below saturation; (2) orifice flow coefficients are not constant as is frequently assumed. A metastable jet appears to exist which breaks down if the difference between back pressure and saturation pressure is large enough.

  9. Humidified high-flow nasal cannula oxygen in bronchiolitis reduces need for invasive ventilation but not intensive care admission.

    Science.gov (United States)

    Goh, Chong Tien; Kirby, Lynette J; Schell, David N; Egan, Jonathan R

    2017-09-01

    To describe the changes to paediatric intensive care unit (PICU) admission patterns and ventilation requirements for children with bronchiolitis following the introduction of humidified high-flow nasal cannula oxygen outside the PICU. Retrospective study comparing patients high-flow nasal cannula oxygen use (year 2008) to those immediately following the introduction of humidified high-flow nasal cannula oxygen use (year 2011) and those following further consolidation of humidified high-flow nasal cannula oxygen use outside the PICU (year 2013). Humidified high-flow nasal cannula oxygen use up to 1 L/kg/min in the hospital did not reduce PICU admission. Intubation rates were reduced from 22.2% in 2008 to 7.8% in 2013. There was a non-significant trend towards decreased length of stay in the PICU while hospital length of stay showed a significant decrease following the introduction of humidified high-flow nasal cannula oxygen. Age high-flow nasal cannula oxygen therapy. Humidified high-flow nasal cannula oxygen utilised outside of the PICU in our institution for children with bronchiolitis did not reduce admission rates or length of stay to the PICU but was associated with a decreasing need for invasive ventilation and reduced hospital length of stay. © 2017 Paediatrics and Child Health Division (The Royal Australasian College of Physicians).

  10. High-flow priapism treated with superselective transcatheter embolization using polyvinyl alcohol particles

    Directory of Open Access Journals (Sweden)

    Sebastián Sánchez-López

    2017-02-01

    Full Text Available Objectives: Priapism is a persistent erection of the penis not associated with sexual stimulation. High-flow priapism is caused by unregulated arterial inflow, usually preceded by perineal or penile blunt trauma and formation of an arterial-lacunar fistula. We present a case of high-flow priapism in a 13-year-old patient managed with polyvinyl alcohol particles. Methods: After obtaining informed consent of the parents of the minor, diagnosis was made with penile Color Doppler Ultrasound and confirmed with flush angiography. Selective arterial embolization was performed with the use of polyvinyl alcohol particles. Results: Complete detumescence was achieved without compromising the patient’s erectile function. Conclusions: The use of permanent occlusive agents like polyvinyl alcohol particles for embolization shows good occlusion rates compared to temporary agents. More studies are needed to find the safer and better agent for the treatment of high flow priapism without compromising erectile function.

  11. An extracorporeal carbon dioxide removal (ECCO2R) device operating at hemodialysis blood flow rates.

    Science.gov (United States)

    Jeffries, R Garrett; Lund, Laura; Frankowski, Brian; Federspiel, William J

    2017-09-06

    Extracorporeal carbon dioxide removal (ECCO2R) systems have gained clinical appeal as supplemental therapy in the treatment of acute and chronic respiratory injuries with low tidal volume or non-invasive ventilation. We have developed an ultra-low-flow ECCO2R device (ULFED) capable of operating at blood flows comparable to renal hemodialysis (250 mL/min). Comparable operating conditions allow use of minimally invasive dialysis cannulation strategies with potential for direct integration to existing dialysis circuitry. A carbon dioxide (CO2) removal device was fabricated with rotating impellers inside an annular hollow fiber membrane bundle to disrupt blood flow patterns and enhance gas exchange. In vitro gas exchange and hemolysis testing was conducted at hemodialysis blood flows (250 mL/min). In vitro carbon dioxide removal rates up to 75 mL/min were achieved in blood at normocapnia (pCO2 = 45 mmHg). In vitro hemolysis (including cannula and blood pump) was comparable to a Medtronic Minimax oxygenator control loop using a time-of-therapy normalized index of hemolysis (0.19 ± 0.04 g/100 min versus 0.12 ± 0.01 g/100 min, p = 0.169). In vitro performance suggests a new ultra-low-flow extracorporeal CO2 removal device could be utilized for safe and effective CO2 removal at hemodialysis flow rates using simplified and minimally invasive connection strategies.

  12. Dynamics, OH distributions and UV emission of a gliding arc at various flow-rates investigated by optical measurements

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Sun, Zhiwei; Li, Zhongshan

    2014-01-01

    We demonstrate a plasma discharge which is generated between two diverging electrodes and extended into a gliding arc in non-equilibrium condition by an air flow at atmospheric pressure. Effects of the air flow rates on the dynamics, ground-state OH distributions and spectral characterization of UV...... occur more frequently at higher flow rates. The anchor points of the gliding arc are mostly steady at the top of the electrodes at lower flow rates whereas at higher flow rates they glide up along the electrodes most of the time. The afterglow of fully developed gliding arcs is observed to decay over......-state OH were investigated using planar laser-induced fluorescence. The results show that the shape, height, intensity and thickness of ground-state OH distribution vary significantly with air flow rates. Finally, UV emission of the gliding arc is measured using optical emission spectroscopy...

  13. The efficacy of centralized flow rate control in 802.11-based wireless mesh networks

    KAUST Repository

    Jamshaid, K.

    2013-06-13

    Commodity WiFi-based wireless mesh networks (WMNs) can be used to provide last mile Internet access. These networks exhibit extreme unfairness with backlogged traffic sources. Current solutions propose distributed source-rate control algorithms requiring link-layer or transport-layer changes on all mesh nodes. This is often infeasible in large practical deployments. In wireline networks, router-assisted rate control techniques have been proposed for use alongside end-to-end mechanisms. We wish to evaluate the feasibility of establishing similar centralized control via gateways in WMNs. In this paper, we focus on the efficacy of this control rather than the specifics of the controller design mechanism. We answer the question: Given sources that react predictably to congestion notification, can we enforce a desired rate allocation through a single centralized controller? The answer is not obvious because flows experience varying contention levels, and transmissions are scheduled by a node using imperfect local knowledge. We find that common router-assisted flow control schemes used in wired networks fail in WMNs because they assume that (1) links are independent, and (2) router queue buildups are sufficient for detecting congestion. We show that non-work-conserving, rate-based centralized scheduling can effectively enforce rate allocation. It can achieve results comparable to source rate limiting, without requiring any modifications to mesh routers or client devices. 2013 Jamshaid et al.; licensee Springer.

  14. Study on transient hydrodynamic performance and cavitation characteristic of high-speed mixed-flow pump

    Science.gov (United States)

    Chen, T.; Sun, Y. B.; Liu, Y. L.; Wu, D. Z.; Wang, L. Q.

    2013-12-01

    In order to analyse the hydrodynamic performance and cavitation characteristic of a high-speed mixed-flow pump during transient operations, experimental studies were carried out. The transient hydrodynamic performance and cavitation characteristics of the mixed-flow pump with guide vane during start-up operation processes were tested on the pump performance test-bed. Performance tests of the pump were carried out under various inlet pressures and speed-changing operations. The real-time instantaneous external characteristics such as rotational speed, hydraulic head, flow rate, suction pressure and discharge pressure of the pump were measured. Based on the experimental results, the effect of fluid acceleration on the hydrodynamic performances and cavitation characteristics of the mixed-flow pump were analysed and evaluated.

  15. Water velocity, turbulence, and migration rate of subyearling fall Chinook salmon in the free-flowing and impounded Snake River

    Science.gov (United States)

    Tiffan, Kenneth F.; Kock, Tobias J.; Haskell, Craig A.; Connor, William P.; Steinhorst, R. Kirk

    2009-01-01

    We studied the migratory behavior of subyearling fall Chinook salmon Oncorhynchus tshawytscha in free-flowing and impounded reaches of the Snake River to evaluate the hypothesis that velocity and turbulence are the primary causal mechanisms of downstream migration. The hypothesis states that impoundment reduces velocity and turbulence and alters the migratory behavior of juvenile Chinook salmon as a result of their reduced perception of these cues. At a constant flow (m3 /s), both velocity (km/d) and turbulence (the SD of velocity) decreased from riverine to impounded habitat as cross-sectional areas increased. We found evidence for the hypothesis that subyearling Chinook salmon perceive velocity and turbulence cues and respond to these cues by varying their behavior. The percentage of the subyearlings that moved faster than the average current speed decreased as fish made the transition from riverine reaches with high velocities and turbulence to upper reservoir reaches with low velocities and turbulence but increased to riverine levels again as the fish moved further down in the reservoir, where velocity and turbulence remained low. The migration rate (km/d) decreased in accordance with longitudinal reductions in velocity and turbulence, as predicted by the hypothesis. The variation in migration rate was better explained by a repeatedmeasures regression model containing velocity (Akaike’s information criterion ¼ 1,769.0) than a model containing flow (2,232.6). We conclude that subyearling fall Chinook salmon respond to changes in water velocity and turbulence, which work together to affect the migration rate.

  16. Effect of flow rate, duty cycle, amplitude, and treatment Time of ultrasonic regimens towards Escherichia coli harbouring lipase

    Science.gov (United States)

    Omar, W. S. A. W.; Sulaiman, A. Z.; Ajit, A.; Chisti, Y.; Chor, A. L. T.

    2017-06-01

    A full factorial design (FFD) approach was conducted to assess the effect of four factors, namely flow rate, duty cycle, amplitude, and treatment time of ultrasonic regimens towards Escherichia coli harbouring lipase. The 22 experiments were performed as the following values with six replicates of centre point: flow rate (0.1, 0.2, and 0.3 L/min), duty cycle (0, 20, and 40 ), amplitude (2, 6, and 10), and treatment time (10, 35, and 60 min). The FFD was employed as preliminary screening in shake flask cultivation to choose the significant factors (Pcoli culture. Also, the designated flow rate and amplitude accordingly showed no effect towards the amount of dry cells weight (DCW). DCW1 was found significantly degraded after the exposure of high duty cycle and treatment time as other factors remained constant. Whereas for the lipase activity, no significant difference was observed in any main factors or interactions. Paired samples t-test confirms the result at a p-value of 0.625. This experimental study suggests the direct and continuous approach of sonication caused an adverse effect on the cells culture density.

  17. Fluorophotometric determination of aqueous humor flow rates in red-tailed hawks (Buteo jamaicensis).

    Science.gov (United States)

    Jones, Michael P; Ward, Daniel A

    2012-04-01

    To determine aqueous humor flow rate (AHFR) in an avian species by use of anterior segment fluorophotometry. 9 healthy red-tailed hawks (Buteo jamaicensis; 4 males and 5 females) that ranged from 8 months to 8 years of age. A protocol was developed for fluorophotometric determination of AHFR. Topical administration of 10% fluorescein was used to load the corneas, and corneal and aqueous humor fluorescein concentrations were measured approximately 5, 6.5, and 8 hours later. Concentration-versus-time plots were generated, and slopes and cornea-to-aqueous humor concentration ratios from these plots were used to manually calculate flow rates. Mean ± SD AHFRs for the right eye, left eye, and both eyes were 3.17 ± 1.36 μL/min (range, 1.67 to 6.21 μL/min), 2.86 ± 0.88 μL/min (range, 2.04 to 4.30 μL/min), and 2.90 ± 0.90 μL/min (range, 1.67 to 4.42 μL/min), respectively. The AHFRs were similar for right and left eyes. These flow rates represented a mean aqueous humor transfer coefficient of 0.0082/min, which is similar to that of mammalian species. The AHFR in red-tailed hawks was similar to that of most mammalian species, and the fractional egress was almost identical to that of other species. This information will allow a greater understanding of aqueous humor flow in avian eyes, which is crucial when evaluating diseases that affect avian eyes as well as medications that alter aqueous humor flow.

  18. Pressure drop-flow rate curves for single-phase steam in Combustion Engineering type steam generator U-tubes during severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Fynan, Douglas A.; Ahn, Kwang-Il, E-mail: kiahn@kaeri.re.kr

    2016-12-15

    Highlights: • Pressure drop-flow rate curves for superheated steam in U-tubes were generated. • Forward flow of hot steam is favored in the longer and taller U-tubes. • Reverse flow of cold steam is favored in short U-tubes. • Steam generator U-tube bundle geometry and tube diameter are important. • Need for correlation development for natural convention heat transfer coefficient. - Abstract: Characteristic pressure drop-flow rate curves are generated for all row numbers of the OPR1000 steam generators (SGs), representative of Combustion Engineering (CE) type SGs featuring square bend U-tubes. The pressure drop-flow rate curves are applicable to severe accident natural circulations of single-phase superheated steam during high pressure station blackout sequences with failed auxiliary feedwater and dry secondary side which are closely related to the thermally induced steam generator tube rupture event. The pressure drop-flow rate curves which determine the recirculation rate through the SG tubes are dependent on the tube bundle geometry and hydraulic diameter of the tubes. The larger CE type SGs have greater variation of tube length and height as a function of row number with forward flow of steam favored in the longer and taller high row number tubes and reverse flow favored in the short low row number tubes. Friction loss, natural convection heat transfer coefficients, and temperature differentials from the primary to secondary side are dominant parameters affecting the recirculation rate. The need for correlation development for natural convection heat transfer coefficients for external flow over tube bundles currently not modeled in system codes is discussed.

  19. Turbulent transport measurements in a cold model of GT-burner at realistic flow rates

    Directory of Open Access Journals (Sweden)

    Gobyzov Oleg

    2016-01-01

    Full Text Available In the present work simultaneous velocity field and passive admixture concentration field measurements at realistic flow-rates conditions in a non-reacting flow in a model of combustion chamber with an industrial mixing device are reported. In the experiments for safety reasons the real fuel (natural gas was replaced with neon gas to simulate stratification in a strongly swirling flow. Measurements were performed by means of planar laser-induced fluorescence (PLIF and particle image velocimetry technique (PIV at Reynolds number, based on the mean flow rate and nozzle diameter, ≈300 000. Details on experimental technique, features of the experimental setup, images and data preprocessing procedures and results of performed measurements are given in the paper. In addition to the raw velocity and admixture concentration data in-depth evaluation approaches aimed for estimation of turbulent kinetic energy (TKE components, assessment of turbulent Schmidt number and analysis of the gradient closure hypothesis from experimental data are presented in the paper.

  20. Analytical expressions for optimum flow rates in evaporators and condensers of heat pumping systems

    Energy Technology Data Exchange (ETDEWEB)

    Granryd, E. [Dept. of Energy Technology, Royal Institute of Technology, KTH, Stockholm (Sweden)

    2010-11-15

    The flow velocities on the air or liquid side of evaporators and condensers in refrigerating or heat pump systems affect the system performance considerably. Furthermore the velocity can often be chosen rather freely without obvious first cost implications. The purpose of the paper is to show analytical relations indicating possible optimum operating conditions. Considering a base case where the design data are known, simple analytical relations are deduced for optimum flow rates that will result in highest overall COP of the system when energy demand for the compressor as well as pumps or fans are included. This optimum is equivalent to the solution for minimum total energy demand of the system for a given cooling load. It is also shown that a different (and higher) flow rate will result in maximum net cooling capacity for a refrigerating system with fixed compressor speed. The expressions can be used for design purposes as well as for checking suitable flow velocities in existing plants. The relations may also be incorporated in algorithms for optimal operation of systems with variable speed compressors. (author)

  1. Estimation of inlet flow rates for image-based aneurysm CFD models: where and how to begin?

    Science.gov (United States)

    Valen-Sendstad, Kristian; Piccinelli, Marina; KrishnankuttyRema, Resmi; Steinman, David A

    2015-06-01

    Patient-specific flow rates are rarely available for image-based computational fluid dynamics models. Instead, flow rates are often assumed to scale according to the diameters of the arteries of interest. Our goal was to determine how choice of inlet location and scaling law affect such model-based estimation of inflow rates. We focused on 37 internal carotid artery (ICA) aneurysm cases from the Aneurisk cohort. An average ICA flow rate of 245 mL min(-1) was assumed from the literature, and then rescaled for each case according to its inlet diameter squared (assuming a fixed velocity) or cubed (assuming a fixed wall shear stress). Scaling was based on diameters measured at various consistent anatomical locations along the models. Choice of location introduced a modest 17% average uncertainty in model-based flow rate, but within individual cases estimated flow rates could vary by >100 mL min(-1). A square law was found to be more consistent with physiological flow rates than a cube law. Although impact of parent artery truncation on downstream flow patterns is well studied, our study highlights a more insidious and potentially equal impact of truncation site and scaling law on the uncertainty of assumed inlet flow rates and thus, potentially, downstream flow patterns.

  2. Investigations on efficiencies of HT solar collectors for different flow rates and collector tilts

    DEFF Research Database (Denmark)

    Chen, Ziqian; Perers, Bengt; Furbo, Simon

    2013-01-01

    Two HT solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one solar collector is equipped with an ETFE foil between the abso......Two HT solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one solar collector is equipped with an ETFE foil between...... the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates and tilt. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rates are obtained. The calculated efficiencies are in good...

  3. The effect of flow rate on the oscillatory activation energy of an oscillating reaction

    Science.gov (United States)

    Monteiro, Emily V.; Varela, Hamilton; Faria, Roberto B.

    2017-09-01

    The simultaneous influence of temperature and flow rate (k0) in the oscillatory regime of the bromate-oxalic acid-acetone-Ce(III) oscillating reaction was investigated. The influence of temperature was evaluated in terms of the oscillatory activation energy (Eω), which was determined at different flow rates. Increasing k0, the oscillatory activation energy is decreased, tending to a limit value, Eω∞. The sensitivity of Eω with k0 is described by the parameter η = dEω/d(1/k0). Eω∞ and η are global properties of any particular oscillating reaction and describes a correlation between the dynamical behavior and temperature, and should be used when comparing different oscillating reactions.

  4. A micromixer with consistent mixing performance for a wide range of flow rates.

    Science.gov (United States)

    Goovaerts, Robert; Van Assche, Tom; Sonck, Marc; Denayer, Joeri; Desmet, Gert

    2015-02-01

    A micromixer with consistent mixing performance for a wide range of flow rates is presented. The mixer makes use of internally moving elements, i.e. steel balls that are located in dedicated mixing chambers. Movement is induced by a rotating magnetic field. To get better insight in differences between active and passive mixing, we studied a mixer that can operate in both regimes. A mixing performance study for a range of flow rates along with pressure drop data is presented. The response of the moving elements in regard to the magnetic field is shown experimentally and shows the limitations of earlier modeling studies. Lastly, the estimated power input on the fluids was calculated and allows for a comparison with more well-known convective-type mixers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Salivary buffer capacity, pH, and stimulated flow rate of crack cocaine users.

    Science.gov (United States)

    Woyceichoski, Iverson Ernani Cogo; Costa, Carlos Henrique; de Araújo, Cristiano Miranda; Brancher, João Armando; Resende, Luciane Grochocki; Vieira, Iran; de Lima, Antonio Adilson Soares

    2013-08-01

    Crack cocaine is the freebase form of cocaine that can be smoked. The use of this drug has been considered a public health problem in many countries. The aim of this study was to assess the stimulated salivary flow rate (SSFR), pH, and the buffer capacity of saliva in crack cocaine users. Stimulated whole saliva was collected from 54 selected crack cocaine users and 40 non-users. All samples were analyzed for SSFR, pH, and buffer capacity. SSFR was analyzed by gravimetric method. The buffer capacity and pH were determined using a digital pH meter. The crack cocaine users demonstrated higher buffer capacity than the control group (P > 0.05). Salivary pH was lower in crack cocaine users (P 0.05). Crack cocaine users might exhibit a significant decrease in salivary pH, but not in salivary flow rate or buffer capacity. © 2012 Blackwell Publishing Asia Pty Ltd.

  6. Model Reference Adaptive Control of the Air Flow Rate of Centrifugal Compressor Using State Space Method

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jaeyoung; Jung, Mooncheong; Yu, Sangseok [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Yi, Sun [North Carolina A and T State Univ., Raleigh (United States)

    2016-08-15

    In this study, a model reference adaptive controller is developed to regulate the outlet air flow rate of centrifugal compressor for automotive supercharger. The centrifugal compressor is developed using the analytical based method to predict the transient behavior of operating and the designed model is validated with experimental data to confirm the system accuracy. The model reference adaptive control structure consists of a compressor model and a MRAC(model reference adaptive control) mechanism. The feedback control do not robust with variation of system parameter but the applied adaptive control is robust even if the system parameter is changed. As a result, the MRAC was regulated to reference air flow rate. Also MRAC was found to be more robust control compared with the feedback control even if the system parameter is changed.

  7. HIGH STRAIN RATE BEHAVIOUR OF AN AZ31 + 0.5 Ca MAGNESIUM ALLOY

    Directory of Open Access Journals (Sweden)

    Josef Pešička

    2012-01-01

    Full Text Available The paper reports behaviour of magnesium alloy AZ31 (nominal composition 3 % Al - 1 % Zn – balance Mg with an addition of 0.5 wt. % Ca at high strain rates. Samples were prepared by the squeeze cast technology. Dynamic compression Hopkinson tests were performed at room temperature with impact velocities ranging from 11.2 to 21.9 m.s-1. A rapid increase of the flow stress and the strain rate sensitivity was observed at high strain rates. Transmission electron microscopy showed extremely high dislocation density and mechanical twins of two types. Adiabatic shear banding is discussed as the reason for the observed behaviour at high strain rates.

  8. Influence of oxygen flow rate on metal-insulator transition of vanadium oxide thin films grown by RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xu; Liu, Xinkun; Li, Haizhu; Huang, Mingju [Henan University, Key Lab of Informational Opto-Electronical Materials and Apparatus, School of Physics and Electronics, Kaifeng (China); Zhang, Angran [South China Normal University, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, Guangzhou (China)

    2017-03-15

    High-quality vanadium oxide (VO{sub 2}) films have been fabricated on Si (111) substrates by radio frequency (RF) magnetron sputtering deposition method. The sheet resistance of VO{sub 2} has a significant change (close to 5 orders of magnitude) in the process of the metal-insulator phase transition (MIT). The field emission-scanning electron microscope (FE-SEM) results show the grain size of VO{sub 2} thin films is larger with the increase of oxygen flow. The X-ray diffraction (XRD) results indicate the thin films fabricated at different oxygen flow rates grow along the (011) crystalline orientation. As the oxygen flow rate increases from 3 sccm to 6 sccm, the phase transition temperature of the films reduces from 341 to 320 K, the width of the thermal hysteresis loop decreases from 32 to 9 K. The thin films fabricated in the condition of 5 sccm have a high temperature coefficient of resistance (TCR) -3.455%/K with a small resistivity of 2.795 ρ/Ω cm. (orig.)

  9. Efficient Unsteady Flow Visualization with High-Order Access Dependencies

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiang; Guo, Hanqi; Yuan, Xiaoru

    2016-04-19

    We present a novel high-order access dependencies based model for efficient pathline computation in unsteady flow visualization. By taking longer access sequences into account to model more sophisticated data access patterns in particle tracing, our method greatly improves the accuracy and reliability in data access prediction. In our work, high-order access dependencies are calculated by tracing uniformly-seeded pathlines in both forward and backward directions in a preprocessing stage. The effectiveness of our proposed approach is demonstrated through a parallel particle tracing framework with high-order data prefetching. Results show that our method achieves higher data locality and hence improves the efficiency of pathline computation.

  10. Effects of chest wall compression on expiratory flow rates in patients with chronic obstructive pulmonary disease

    OpenAIRE

    Masafumi Nozoe; Kyoshi Mase; Tomoyuki Ogino; Shigefumi Murakami; Sachie Takashima; Kazuhisa Domen

    2016-01-01

    Background: Manual chest wall compression (CWC) during expiration is a technique for removing airway secretions in patients with respiratory disorders. However, there have been no reports about the physiological effects of CWC in patients with chronic obstructive pulmonary disease (COPD). Objective: To compare the effects of CWC on expiratory flow rates in patients with COPD and asymptomatic controls. Method: Fourteen subjects were recruited from among patients with COPD who were receivi...

  11. Development and evaluation of a meter for measuring return line fluid flow rates during drilling

    Energy Technology Data Exchange (ETDEWEB)

    Loeppke, G.E.; Schafer, D.M.; Glowka, D.A.; Scott, D.D.; Wernig, M.D. (Sandia National Labs., Albuquerque, NM (United States)); Wright, E.K. (Ktech Corp., Albuquerque, NM (United States))

    1992-06-01

    The most costly problem routinely encountered in geothermal drilling is lost circulation, which occurs when drilling fluid is lost to the formation rather than circulating back to the surface. The successful and economical treatment of lost circulation requires the accurate measurement of drilling fluid flow rate both into and out of the well. This report documents the development of a meter for measuring drilling fluid outflow rates in the return line of a drilling rig. The meter employs a rolling counterbalanced float that rides on the surface of the fluid in the return line. The angle of the float pivot arm is sensed with a pendulum potentiometer, and the height of the float is calculated from this measurement. The float height is closely related to the fluid height and, therefore, the flow rate in the line. The prototype rolling float meter was extensively tested under laboratory conditions in the Wellbore Hydraulics Flow Facility; results from these tests were used in the design of the field prototype rolling float meter. The field prototype meter was tested under actual drilling conditions in August and September 1991 at the Long Valley Exploratory Well near Mammoth Lakes, Ca. In addition, the performance of several other commercially available inflow and outflow meters was evaluated in the field. The tested inflow meters included conventional pump stroke counters, rotary pump speed counters, magnetic flowmeters, and an ultrasonic Doppler flowmeter. On the return flow line, a standard paddlemeter, an acoustic level meter, and the prototype rolling float meter were evaluated for measuring drilling fluid outflow rates.

  12. Rate-Based Active Queue Management for TCP Flows over Wired and Wireless Networks

    OpenAIRE

    Jun Wang; Min Song

    2007-01-01

    Current active queue management (AQM) and TCP protocol are designed and tuned to work well on wired networks where packet loss is mainly due to network congestion. In wireless networks, however, communication links suffer from significant transmission bit errors and handoff failures. As a result, the performance of TCP flows is significantly degraded. To mitigate this problem, we analyze existing AQM schemes and propose a rate-based exponential AQM (REAQM) scheme. The proposed REAQM scheme u...

  13. Predicting Hourly Traflc Noise from Traflc Flow Rate Model: Underlying Concepts for the DYNAMAP Project

    OpenAIRE

    Smiraglia M.; Benocci R.; Zambon G.; Roman H.E.

    2016-01-01

    The DYNAMAP project aims at obtaining a dynamic noise map of a large residential area such as the City of Milan (Italy), by recording traffic noise from a limited number of noise sensors. To this end,we perform a statistical analysis of road stretches and group them into different clusters showing a similar measured hourly traffic noise behavior. In the sameway,we group simulated hourly traffic flow rates and compare their compositions with those of the traffic noise g...

  14. Determination of salivary flow rate, pH, and dental caries during pregnancy: A study

    Directory of Open Access Journals (Sweden)

    Amruta A Karnik

    2015-01-01

    Full Text Available Introduction: Saliva is an important diagnostic biofluid and the salivary composition is affected by various systemic conditions including pregnancy. Aims: The study was conducted to evaluate the salivary flow rate and pH in pregnant and non-pregnant Indian women and, consequently, to compare and correlate the salivary flow rate, pH, and prevalence of dental caries in both groups. Settings and Design: A cross-sectional study was conducted in our institute on a sample of 30 pregnant and 30 non-pregnant women. Materials and Methods: The clinical findings for Decayed-Missing-Filled Teeth (DMFT index were recorded. Unstimulated whole saliva was collected to determine the salivary flow rate and pH. Statistical Analysis Used: Data were statistically analyzed using Student′s t-test. Results: Salivary flow rate was lower in pregnant women (0.63 ml/min as compared to that in non-pregnant women (0.81 ml/min (P < 0.05 and the pH was also lesser in pregnant women (6.56 than in non-pregnant women (6.86 (P < 0.05. DMFT index showed a strong negative correlation with pH in pregnant women and non-pregnant women (P < 0.05. Conclusion: A difference was observed between the salivary parameters of pregnant and non-pregnant women in this sample. However, all the values were within the normal range. A significant inverse relation was found between salivary pH and dental caries for both the groups.

  15. Porcine In Vivo Validation of a Virtual Contrast Model: The Influence of Contrast Agent Properties and Vessel Flow Rates.

    Science.gov (United States)

    Peach, T W; Ventikos, Y; Byrne, J V; You, Z

    2016-12-01

    Accurately and efficiently modeling the transport of angiographic contrast currently offers the best method of verifying computational fluid dynamics simulations and, with it, progress toward the lofty goal of prediction of aneurysm treatment outcome a priori. This study specifically examines the influence of estimated flow rate and contrast properties on such in silico predictions of aneurysm contrast residence and decay. Four experimental sidewall aneurysms were created in swine, with aneurysm contrast flow patterns and decay rates observed under angiography. A simplified computational fluid dynamics model of the experimental aneurysm was constructed from 3D angiography and contrast residence predicted a priori. The relative influence of a number of estimated model parameters (contrast viscosity, contrast density, and blood flow rate) on contrast residence was then investigated with further simulations. Contrast infiltration and washout pattern were accurately predicted by the a priori computational fluid dynamics model; however, the contrast decay rate was underestimated by ∼25%. This error was attributed to the estimated parent vessel flow rate alone, and the effects of contrast viscosity and density on the decay rate were found to be inconsequential. A linear correlation between the parent vessel flow rate and the corresponding contrast decay rate was observed. In experimental sidewall aneurysms, contrast fluid properties (viscosity and density) were shown to have a negligible effect on variation in the modeled contrast decay rate. A strong linear correlation was observed between parent vessel flow rate and contrast decay over a physiologically reasonable range of flow rates. © 2016 by American Journal of Neuroradiology.

  16. Heart rate in the pathophysiology of coronary blood flow and myocardial ischaemia: benefit from selective bradycardic agents

    Science.gov (United States)

    Heusch, G

    2008-01-01

    Starting out from a brief description of the determinants of coronary blood flow (perfusion, pressure, extravascular compression, autoregulation, metabolic regulation, endothelium-mediated regulation and neurohumoral regulation) the present review highlights the overwhelming importance of metabolic regulation such that coronary blood flow is increased at increased heart rate under physiological circumstances and the overwhelming importance of extravascular compression such that coronary blood flow is decreased at increased heart rate through reduction of diastolic duration in the presence of severe coronary stenoses. The review goes on to characterize the role of heart rate in the redistribution of regional myocardial blood flow between a normal coronary vascular tree with preserved autoregulation and a poststenotic vasculature with exhausted coronary reserve. When flow is normalized by heart rate, there is a consistent close relationship of regional myocardial blood flow and contractile function for each single cardiac cycle no matter whether or not there is a coronary stenosis and what the actual blood flow is. β-Blockade improves both flow and function along this relationship. When the heart rate reduction associated with β-blockade is prevented by pacing, α-adrenergic coronary vasoconstriction is unmasked and both flow and function are deteriorated. Selective heart rate reduction, however, improves both flow and function without any residual negative effect such as unmasked α-adrenergic coronary vasoconstriction or negative inotropic action. PMID:18223669

  17. Atomistic Origin of Rate-Dependent Serrated Plastic Flow in Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Yao YG

    2008-01-01

    Full Text Available Abstract Nanoindentation simulations on a binary metallic glass were performed under various strain rates by using molecular dynamics. The rate-dependent serrated plastic flow was clearly observed, and the spatiotemporal behavior of its underlying irreversible atomic rearrangement was probed. Our findings clearly validate that the serration is a temporally inhomogeneous characteristic of such rearrangements and not directly dependent on the resultant shear-banding spatiality. The unique spatiotemporal distribution of shear banding during nanoindentation is highlighted in terms of the potential energy landscape (PEL theory.

  18. Characterization of a Porous Nano-electrospray Capillary Emitter at Ultra-low Flow Rates.

    Science.gov (United States)

    Jarvas, Gabor; Fonslow, Bryan; Yates, John R; Foret, Frantisek; Guttman, Andras

    2017-01-01

    Biopharmaceuticals, especially therapeutic monoclonal antibodies, have emerged as a very promising new generation of protein-based drugs. However, their comprehensive analysis continues to pose new challenges for the bioanalytical field. Hyphenation of capillary electrophoresis with electrospray ionization (CE-MS) is a promising technique to address these challenges. One of the main advantages of CE-MS is the ability to produce stable electrospray at ultra-low flow rates (5-20 nl/min range). In this short communication we report on the characterization of a porous nano-electrospray capillary emitter focusing on the effects of ultra-low flow rate on ionization efficiency, ion suppression and detection sensitivity. Ion suppression effect of a poorly-ionizable sugar in the presence of an easily-ionized peptide was reduced by almost 2-fold. Intact therapeutic antibody infusion analysis demonstrated that MS detection sensitivity increased by an order of magnitude with the decrease of flow rate from 250 nL/min to 20 nL/min using the nano-electrospray capillary emitter. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Relationship between xerostomia and salivary flow rates in HIV-infected individuals.

    Science.gov (United States)

    Nittayananta, Wipawee; Chanowanna, Nilnara; Pruphetkaew, Nannapat; Nauntofte, Birgitte

    2013-08-01

    The aim of the present study was to determine the relationship between self-reported xerostomia and salivary flow rates among HIV-infected individuals. A cross-sectional study was performed on 173 individuals (81 HIV-infected individuals, mean age: 32 years, and 92 non-HIV controls, mean age: 30 years). Subjective complaints of dry mouth, based on a self-report of xerostomia questions, and dry mouth, based on a visual analogue scale (VAS), were recorded along with measurements of salivary flow rate of both unstimulated and wax-stimulated whole saliva. The relationship between subjective responses to the xerostomia questions, the VAS of dry mouth, and objective measurements of salivary flow rates were analyzed. Responses to the questions--Do you carry water or a saliva substitute? and Have you had taste disturbance?--were significantly different between HIV-infected and non-HIV individuals (P hyposalivation, especially at a resting stage. © 2013 Wiley Publishing Asia Pty Ltd.

  20. Salivary flow rate and biochemical composition analysis in stimulated whole saliva of children with cystic fibrosis.

    Science.gov (United States)

    da Silva Modesto, Karine Barros; de Godói Simões, Jéssica Bueno; de Souza, Amanda Ferreira; Damaceno, Neiva; Duarte, Danilo Antonio; Leite, Mariana Ferreira; de Almeida, Eliete Rodrigues

    2015-11-01

    It is recognized that cystic fibrosis (CF) patients present a risk for oral diseases, since it affects exocrine glands, and the treatment consists of a carbohydrate-rich diet. Recognizing the protective function of saliva on maintaining oral health, the aim of the study was to evaluate salivary parameters in stimulated whole saliva from children with CF. A case-control study was conducted comparing stimulated whole saliva of healthy (n=28; control group) and CF children (n=21; experimental group). Salivary flow rate, initial pH, buffer capacity (total and in each range of pH), total protein and sialic acid (total, free, and conjugated) concentration, α-amylase and salivary peroxidase activities were evaluated. Data were compared by two-tailed Student t test (95% CI; p ≤ 0.05). CF patients presented a significant reduction in salivary parameters compared with the control group (p ≤ 0.05): salivary flow rate (36%), buffer capacity (pH range from 6.9 to 6.0), sialic acid concentration (total 75%, free 61%, and conjugated 83%); α-amylase and salivary peroxidase activities (55%). Additionally, a significant increase in total protein concentration (180%) of stimulated whole saliva from CF patients was verified compared with the control group (p ≤ 0.05). Children with CF presented significant changes in salivary composition, including salivary flow rate, buffering capacity and protective proteins of the oral cavity, compared with children without CF. Copyright © 2015 Elsevier Ltd. All rights reserved.