Science.gov

Sample records for moderator flow measurements

  1. Electrified film flows at moderate Reynolds number

    NASA Astrophysics Data System (ADS)

    Craster, Richard; Wray, Alex; Papageorgiou, Demetrios; Matar, Omar

    2014-11-01

    We examine the flow of a thin, inclined film sandwiched between two parallel electrodes. We follow the Weighted Residual Integral Boundary Layer method, which has been shown via comparison with both direct numerical simulations and experiments to give good results in both the drag-gravity and drag-inertia regimes. We extend existing models to give an accurate model of electrostatic effects via a similar separation of variables approach. A disparity in material properties between the liquid and gas regions induces a Maxwell stress at the interface, which affords a significant degree of control over the behaviour of the film. In one dimension, linear stability comparisons are made with a full Orr-Sommerfeld calculation, and nonlinear comparisons are made with direct numerical simulations, both showing excellent agreement in large parts of parameter space. The model is also extended to fully two-dimensional simulations. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1, EPSRC DTG Studentship (AWW).

  2. MODFLOW 2. 0: A program for predicting moderator flow patterns

    SciTech Connect

    Peterson, P.F. . Dept. of Nuclear Engineering); Paik, I.K. )

    1991-07-01

    Sudden changes in the temperature of flowing liquids can result in transient buoyancy forces which strongly impact the flow hydrodynamics via flow stratification. These effects have been studied for the case of potential flow of stratified liquids to line sinks, but not for moderator flow in SRS reactors. Standard codes, such as TRAC and COMMIX, do not have the capability to capture the stratification effect, due to strong numerical diffusion which smears away the hot/cold fluid interface. A related problem with standard codes is the inability to track plumes injected into the liquid flow, again due to numerical diffusion. The combined effects of buoyant stratification and plume dispersion have been identified as being important in operation the Supplementary Safety System which injects neutron-poison ink into SRS reactors to provide safe shutdown in the event of safety rod failure. The MODFLOW code discussed here provides transient moderator flow pattern information with stratification effects, and tracks the location of ink plumes in the reactor. The code, written in Fortran, is compiled for Macintosh II computers, and includes subroutines for interactive control and graphical output. Removing the graphics capabilities, the code can also be compiled on other computers. With graphics, in addition to the capability to perform safety related computations, MODFLOW also provides an easy tool for becoming familiar with flow distributions in SRS reactors.

  3. Whistle Gauge Measures Flow And Temperature

    NASA Technical Reports Server (NTRS)

    Shakkottai, Parthasarathy; Kwack, Eug Y.

    1989-01-01

    Simple, rugged gauge used to measure speed of flow and temperature of steam or other gas flowing through pipes of arbitrary diameter, from 1 to 28 in. or larger. Specially designed, instrumented whistle - has no moving parts, small, nonobstruction, operates at high temperature and pressure, and cleans itself. Does not operate at zero flow, but at moderate flows (tens of meters per second) generates intense sound for use in measurements. Consists of slanted ring groove of depth D and pressure taps in wall of pipe carrying flow to be measured. Resonant wavelength of sound generated by ring groove depends primarily on size and shape of groove and approximately equal to 4D.

  4. Stressful Life Events: Measurement, Moderators, and Adaptation.

    DTIC Science & Technology

    1980-10-10

    tolerance for stimulation, sensation seeking as a personality attribute may well serve as an important moderator of life stress. High sensation seekers...experiencing stressful life events and psychological well -being. A helping spouse seems to be particularly valuable in contributing to self- confidence...7. Crnic, K. A., Greenberg, M. T., Ragozin, A. S., & Robinson, N. M. The effects of life stress and social support on the life satisfaction and

  5. Planetary heat flow measurements.

    PubMed

    Hagermann, Axel

    2005-12-15

    The year 2005 marks the 35th anniversary of the Apollo 13 mission, probably the most successful failure in the history of manned spaceflight. Naturally, Apollo 13's scientific payload is far less known than the spectacular accident and subsequent rescue of its crew. Among other instruments, it carried the first instrument designed to measure the flux of heat on a planetary body other than Earth. The year 2005 also should have marked the launch of the Japanese LUNAR-A mission, and ESA's Rosetta mission is slowly approaching comet Churyumov-Gerasimenko. Both missions carry penetrators to study the heat flow from their target bodies. What is so interesting about planetary heat flow? What can we learn from it and how do we measure it?Not only the Sun, but all planets in the Solar System are essentially heat engines. Various heat sources or heat reservoirs drive intrinsic and surface processes, causing 'dead balls of rock, ice or gas' to evolve dynamically over time, driving convection that powers tectonic processes and spawns magnetic fields. The heat flow constrains models of the thermal evolution of a planet and also its composition because it provides an upper limit for the bulk abundance of radioactive elements. On Earth, the global variation of heat flow also reflects the tectonic activity: heat flow increases towards the young ocean ridges, whereas it is rather low on the old continental shields. It is not surprising that surface heat flow measurements, or even estimates, where performed, contributed greatly to our understanding of what happens inside the planets. In this article, I will review the results and the methods used in past heat flow measurements and speculate on the targets and design of future experiments.

  6. Structural power flow measurement

    SciTech Connect

    Falter, K.J.; Keltie, R.F.

    1988-12-01

    Previous investigations of structural power flow through beam-like structures resulted in some unexplained anomalies in the calculated data. In order to develop structural power flow measurement as a viable technique for machine tool design, the causes of these anomalies needed to be found. Once found, techniques for eliminating the errors could be developed. Error sources were found in the experimental apparatus itself as well as in the instrumentation. Although flexural waves are the carriers of power in the experimental apparatus, at some frequencies longitudinal waves were excited which were picked up by the accelerometers and altered power measurements. Errors were found in the phase and gain response of the sensors and amplifiers used for measurement. A transfer function correction technique was employed to compensate for these instrumentation errors.

  7. Heat Flow Measurement

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Heat gauges are used to measure heat flow in industrial activities. They must periodically be certified by instruments designed to provide a heat flux measurement standard. CSTAR, a NASA CCDS, and REMTECH have developed a portable heat flux checker/calibrator. The Q-CHEC can be carried to the heat gauge for certification, reducing out of service time for the gauge and eliminating the need for a replacement gauge during certification. It can provide an "end-to-end" check of the instrumentation measurement system or be used as a standalone calibrator. Because Q-CHEC offers on-site capability to detect and eliminate measurement errors, measurements do not have to be repeated, and money is saved.

  8. Three-dimensional modeling of flow and deformation in idealized mild and moderate arterial vessels.

    PubMed

    Gu, Xi; Yeoh, Guan Heng; Timchenko, Victoria

    2016-10-01

    Three-dimensional numerical calculations of mild and moderate stenosed blood vessels have been performed. Large eddy simulation through a dynamic subgrid scale Smagorinsky model is applied to model the transitional and turbulent pulsatile flow. For the compliant stenosed model, fluid-structure interaction is realized through a two-way coupling between the fluid flow and the deforming vessel through the change in the external diameter due to the increment of circumferential pressure via a novel moving boundary approach. Model predictions compare very well against measured and numerical data for the centerline velocities, thickness of the flow separation zones and radial wall displacements.

  9. Flow quality measurements in compressible subsonic flows

    NASA Technical Reports Server (NTRS)

    Stainback, P. Calvin; Johnson, Charles B.

    1987-01-01

    The purpose is to re-examine the heat transfer from a hot-wire probe in the compressible subsonic flow regime; describe the three-wire hot-wire probe calibration and data reduction techniques used to measure the velocity, density, and total temperature fluctuation; and present flow quality results obtained in the Langley 0.3 meter Transonic Cryogenic Wind Tunnel and in flight with the NASA JetStar from the same three-wire hot-wire probe.

  10. Experiments on the flow and acoustic properties of a moderate-Reynolds-number supersonic jet

    NASA Technical Reports Server (NTRS)

    Troutt, T. R.; Mclaughlin, D. K.

    1982-01-01

    Flow and acoustic properties of a jet at Reynolds number of 70,000 were studied at Mach 2.1. Measurements in a free jet test facility were made with pitot tubes and hot-wire anemometry. Center-line Mach number distributions for natural and excited jets were obtained. A slow initial growth rate was in the potential core region of the jet, indicating a transition from laminar to turbulent flow in moderate Reynolds number jets. The transition occurred within the first 2-3 diameters. Spectral components were calculated for the fluctuating flowfield, and sound pressure levels were measured for the overall near-field noise. The centroid of noise was located about 8 nozzle diameters downstream. The growth rates of instabilities were determined to be in agreement with linear stability theory predictions over a broad frequency range.

  11. Endovascular blood flow measurement system

    NASA Astrophysics Data System (ADS)

    Khe, A. K.; Cherevko, A. A.; Chupakhin, A. P.; Krivoshapkin, A. L.; Orlov, K. Yu

    2016-06-01

    In this paper an endovascular measurement system used for intraoperative cerebral blood flow monitoring is described. The system is based on a Volcano ComboMap Pressure and Flow System extended with analogue-to-digital converter and PC laptop. A series of measurements performed in patients with cerebrovascular pathologies allows us to introduce “velocity-pressure” and “flow rate-energy flow rate” diagrams as important characteristics of the blood flow. The measurement system presented here can be used as an additional instrument in neurosurgery for assessment and monitoring of the operation procedure. Clinical data obtained with the system are used for construction of mathematical models and patient-specific simulations. The monitoring of the blood flow parameters during endovascular interventions was approved by the Ethics Committee at the Meshalkin Novosibirsk Research Institute of Circulation Pathology and included in certain surgical protocols for pre-, intra- and postoperative examinations.

  12. Invariant Measures for Cherry Flows

    NASA Astrophysics Data System (ADS)

    Saghin, Radu; Vargas, Edson

    2013-01-01

    We investigate the invariant probability measures for Cherry flows, i.e. flows on the two-torus which have a saddle, a source, and no other fixed points, closed orbits or homoclinic orbits. In the case when the saddle is dissipative or conservative we show that the only invariant probability measures are the Dirac measures at the two fixed points, and the Dirac measure at the saddle is the physical measure. In the other case we prove that there exists also an invariant probability measure supported on the quasi-minimal set, we discuss some situations when this other invariant measure is the physical measure, and conjecture that this is always the case. The main techniques used are the study of the integrability of the return time with respect to the invariant measure of the return map to a closed transversal to the flow, and the study of the close returns near the saddle.

  13. Natural Laminar Flow Design for Wings with Moderate Sweep

    NASA Technical Reports Server (NTRS)

    Campbell, Richard L.; Lynde, Michelle N.

    2016-01-01

    A new method for the aerodynamic design of wings with natural laminar flow is under development at the NASA Langley Research Center. The approach involves the addition of new flow constraints to an existing knowledge-based design module for use with advanced flow solvers. The uniqueness of the new approach lies in the tailoring of target pressure distributions to achieve laminar flow on transonic wings with leading-edge sweeps and Reynolds numbers typical of current transports. The method is demonstrated on the Common Research Model configuration at critical N-factor levels representative of both flight and high-Reynolds number wind tunnel turbulence levels. The design results for the flight conditions matched the target extent of laminar flow very well. The design at wind tunnel conditions raised some design issues that prompted further improvements in the method, but overall has given promising results.

  14. DNS and LES of Separated Flows at Moderate Reynolds Numbers

    NASA Astrophysics Data System (ADS)

    Cadieux, F.; Domaradzki, J. A.; Sayadi, T.; Bose, S.; Duchaine, F.

    2012-11-01

    Flows in rotating machinery, for unmanned and micro aerial vehicles, wind turbines, and propellers consist of different flow regimes. First, a laminar boundary layer is followed by a laminar separation bubble with a shear layer on top of it that experiences transition to turbulence. Subsequently, the separated turbulent flow reattaches and evolves downstream from a nonequilibrium turbulent boundary layer to an equilibrium one. Typical RANS and LES turbulence modeling methods experience difficulties when simulating such flows because they were developed for fully developed turbulent flows. This currently leaves DNS as the only reliable but computationally expensive alternative. Our work assesses the capability of LES to reduce the resolution requirements for such flows. Flow over a flat plate with suitable velocity boundary conditions away from the plate to produce a separation bubble is considered. Benchmark DNS data for this configuration was generated with the resolution of 50 ×106 mesh points; also used was a different DNS database with 15 ×106 points reported by Spalart and Strelets in JFM 403 (2000). Employing two codes, one using structured and another unstructured mesh, we concluded that accurate LES are possible using O(1%) of the DNS resolution. Work performed during Stanford-CTR Summer Program 2012.

  15. Apparatus for measuring fluid flow

    DOEpatents

    Smith, J.E.; Thomas, D.G.

    Flow measuring apparatus includes a support loop having strain gages mounted thereon and a drag means which is attached to one end of the support loop and which bends the sides of the support loop and induces strains in the strain gages when a flow stream impacts thereon.

  16. Apparatus for measuring fluid flow

    DOEpatents

    Smith, Jack E.; Thomas, David G.

    1984-01-01

    Flow measuring apparatus includes a support loop having strain gages mounted thereon and a drag means which is attached to one end of the support loop and which bends the sides of the support loop and induces strains in the strain gages when a flow stream impacts thereon.

  17. Measuring sap flow in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sap flow measurements provide a powerful tool for quantifying plant water use and monitoring qualitative physiological responses of plants to environmental conditions. As such, sap flow methods are widely employed to invesitgate the agronomic, ecological and hydrological outcomes of plant growth. T...

  18. Wireless sap flow measurement system

    NASA Astrophysics Data System (ADS)

    Kuo, C.; Davis, T. W.; Tseng, C.; Cheng, C.; Liang, X.; Yu, P.

    2010-12-01

    This study exhibits a measurement system for wireless sensor networks to measure sap flow in multiple locations simultaneously. Transpiration is a major component of the land-surface system because it is indicative of the water movement between the soil and the air. Sap flow can be used to approximate transpiration. In forests, transpiration cannot be represented by the sap flow from a single tree. Multi-location sap flow measurements are required to show the heterogeneity caused by different trees or soil conditions. Traditional multi-location measurements require manpower and capital for data collection and instrument maintenance. Fortunately, multi-location measurements can be achieved by using the new technology of wireless sensor networks. With multi-hop communication protocol, data can be forwarded to the base station via multiple sensor nodes. This communication protocol can provide reliable data collection with the least power consumption. This study encountered two major problems. The first problem was signal amplification. The Crossbow IRIS mote was selected as the sensor node that receives the temperature data of the sap flow probe (thermocouple) through a MDA300 data acquisition board. However, the wireless sensor node could not directly receive any data from the thermocouples since the least significant bit value of the MDA300, 0.6 mV, is much higher than the voltage signal generated. Thus, the signal from the thermocouple must be amplified to exceed this threshold. The second problem is power management. A specific heat differential is required for the thermal dissipation method of measuring sap flow. Thus, an adjustable DC power supply is necessary for calibrating the heater's temperature settings. A circuit was designed to combine the signal amplifier and power regulator. The regulator has been designed to also provide power to the IRIS mote to extend battery life. This design enables wireless sap flow measurements in the forest. With the

  19. Surface flow measurements from drones

    NASA Astrophysics Data System (ADS)

    Tauro, Flavia; Porfiri, Maurizio; Grimaldi, Salvatore

    2016-09-01

    Drones are transforming the way we sense and interact with the environment. However, despite their increased capabilities, the use of drones in geophysical sciences usually focuses on image acquisition for generating high-resolution maps. Motivated by the increasing demand for innovative and high performance geophysical observational methodologies, we posit the integration of drone technology and optical sensing toward a quantitative characterization of surface flow phenomena. We demonstrate that a recreational drone can be used to yield accurate surface flow maps of sub-meter water bodies. Specifically, drone's vibrations do not hinder surface flow observations, and velocity measurements are in agreement with traditional techniques. This first instance of quantitative water flow sensing from a flying drone paves the way to novel observations of the environment.

  20. PIV measurements of isothermal plane turbulent impinging jets at moderate Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Khayrullina, A.; van Hooff, T.; Blocken, B.; van Heijst, G. J. F.

    2017-04-01

    This paper contains a detailed experimental analysis of an isothermal plane turbulent impinging jet (PTIJ) for two jet widths at moderate Reynolds numbers (7200-13,500) issued on a horizontal plane at fixed relative distances equal to 22.5 and 45 jet widths. The available literature on such flows is scarce. Previous studies on plane turbulent jets mainly focused on free jets, while most studies on impinging jets focused on the heat transfer between the jet and an impingement plane, disregarding jet development. The present study focuses on isothermal PTIJs at moderate Reynolds numbers characteristic of air curtains. Flow visualisations with fluorescent dye and 2D particle image velocimetry (PIV) measurements have been performed. A comparison is made with previous studies of isothermal free turbulent jets at moderate Reynolds numbers. Mean and instantaneous velocity and vorticity, turbulence intensity, and Reynolds shear stress are analysed. The jet issued from the nozzle with higher aspect ratio shows more intensive entrainment and a faster decay of the centreline velocity compared to the jet of lower aspect ratio for the same value of jet Reynolds number. The profiles of centreline and cross-jet velocity and turbulence intensity show that the PTIJs behave as a free plane turbulent jet until 70-75% of the total jet height. Alongside the information obtained on the jet dynamics, the data will be useful for the validation of numerical simulations.

  1. "Influence Method" applied to measure a moderated neutron flux

    NASA Astrophysics Data System (ADS)

    Rios, I. J.; Mayer, R. E.

    2016-01-01

    The "Influence Method" is conceived for the absolute determination of a nuclear particle flux in the absence of known detector efficiency. This method exploits the influence of the presence of one detector, in the count rate of another detector when they are placed one behind the other and define statistical estimators for the absolute number of incident particles and for the efficiency. The method and its detailed mathematical description were recently published (Rios and Mayer, 2015 [1]). In this article we apply it to the measurement of the moderated neutron flux produced by an 241AmBe neutron source surrounded by a light water sphere, employing a pair of 3He detectors. For this purpose, the method is extended for its application where particles arriving at the detector obey a Poisson distribution and also, for the case when efficiency is not constant over the energy spectrum of interest. Experimental distributions and derived parameters are compared with theoretical predictions of the method and implications concerning the potential application to the absolute calibration of neutron sources are considered.

  2. Measurement in multiphase reacting flows

    NASA Technical Reports Server (NTRS)

    Chigier, N. A.

    1979-01-01

    A survey is presented of diagnostic techniques and measurements made in multiphase reacting flows. The special problems encountered by the presence of liquid droplets, soot and solid particles in high temperature chemically reacting turbulent environments are outlined. The principal measurement techniques that have been tested in spray flames are spark photography, laser anemometry, thermocouples and suction probes. Spark photography provides measurement of drop size, drop size distribution, drop velocity, and angle of flight. Photographs are analysed automatically by image analysers. Photographic techniques are reliable, inexpensive and proved. Laser anemometers have been developed for simultaneous measurement of velocity and size of individual particles in sprays under conditions of vaporization and combustion. Particle/gas velocity differentials, particle Reynolds numbers, local drag coefficients and direct measurement of vaporization rates can be made by laser anemometry. Gas temperature in sprays is determined by direct in situ measurement of time constants immediately prior to measurement with compensation and signal analysis by micro-processors. Gas concentration is measured by suction probes and gas phase chromatography. Measurements of particle size, particle velocity, gas temperature, and gas concentration made in airblast and pressure atomised liquid spray flames are presented.

  3. Evaluation of flow hood measurements for residential register flows

    SciTech Connect

    Walker, I.S.; Wray, C.P.; Dickerhoff, D.J.; Sherman, M.H.

    2001-09-01

    Flow measurement at residential registers using flow hoods is becoming more common. These measurements are used to determine if the HVAC system is providing adequate comfort, appropriate flow over heat exchangers and in estimates of system energy losses. These HVAC system performance metrics are determined by using register measurements to find out if individual rooms are getting the correct airflow, and in estimates of total air handler flow and duct air leakage. The work discussed in this paper shows that commercially available flow hoods are poor at measuring flows in residential systems. There is also evidence in this and other studies that flow hoods can have significant errors even when used on the non-residential systems they were originally developed for. The measurement uncertainties arise from poor calibrations and the sensitivity of exiting flow hoods to non-uniformity of flows entering the device. The errors are usually large--on the order of 20% of measured flow, which is unacceptably high for most applications. Active flow hoods that have flow measurement devices that are insensitive to the entering airflow pattern were found to be clearly superior to commercially available flow hoods. In addition, it is clear that current calibration procedures for flow hoods may not take into account any field application problems and a new flow hood measurement standard should be developed to address this issue.

  4. MODFLOW 2.0: A program for predicting moderator flow patterns

    SciTech Connect

    Peterson, P.F.; Paik, I.K.

    1991-07-01

    Sudden changes in the temperature of flowing liquids can result in transient buoyancy forces which strongly impact the flow hydrodynamics via flow stratification. These effects have been studied for the case of potential flow of stratified liquids to line sinks, but not for moderator flow in SRS reactors. Standard codes, such as TRAC and COMMIX, do not have the capability to capture the stratification effect, due to strong numerical diffusion which smears away the hot/cold fluid interface. A related problem with standard codes is the inability to track plumes injected into the liquid flow, again due to numerical diffusion. The combined effects of buoyant stratification and plume dispersion have been identified as being important in operation the Supplementary Safety System which injects neutron-poison ink into SRS reactors to provide safe shutdown in the event of safety rod failure. The MODFLOW code discussed here provides transient moderator flow pattern information with stratification effects, and tracks the location of ink plumes in the reactor. The code, written in Fortran, is compiled for Macintosh II computers, and includes subroutines for interactive control and graphical output. Removing the graphics capabilities, the code can also be compiled on other computers. With graphics, in addition to the capability to perform safety related computations, MODFLOW also provides an easy tool for becoming familiar with flow distributions in SRS reactors.

  5. Code requirements document: MODFLOW 2. 1: A program for predicting moderator flow patterns

    SciTech Connect

    Peterson, P.F. . Dept. of Nuclear Engineering); Paik, I.K. )

    1992-03-01

    Sudden changes in the temperature of flowing liquids can result in transient buoyancy forces which strongly impact the flow hydrodynamics via flow stratification. These effects have been studied for the case of potential flow of stratified liquids to line sinks, but not for moderator flow in SRS reactors. Standard codes, such as TRAC and COMMIX, do not have the capability to capture the stratification effect, due to strong numerical diffusion which smears away the hot/cold fluid interface. A related problem with standard codes is the inability to track plumes injected into the liquid flow, again due to numerical diffusion. The combined effects of buoyant stratification and plume dispersion have been identified as being important in operation of the Supplementary Safety System which injects neutron-poison ink into SRS reactors to provide safe shutdown in the event of safety rod failure. The MODFLOW code discussed here provides transient moderator flow pattern information with stratification effects, and tracks the location of ink plumes in the reactor. The code, written in Fortran, is compiled for Macintosh II computers, and includes subroutines for interactive control and graphical output. Removing the graphics capabilities, the code can also be compiled on other computers. With graphics, in addition to the capability to perform safety related computations, MODFLOW also provides an easy tool for becoming familiar with flow distributions in SRS reactors.

  6. Code requirements document: MODFLOW 2.1: A program for predicting moderator flow patterns

    SciTech Connect

    Peterson, P.F.; Paik, I.K.

    1992-03-01

    Sudden changes in the temperature of flowing liquids can result in transient buoyancy forces which strongly impact the flow hydrodynamics via flow stratification. These effects have been studied for the case of potential flow of stratified liquids to line sinks, but not for moderator flow in SRS reactors. Standard codes, such as TRAC and COMMIX, do not have the capability to capture the stratification effect, due to strong numerical diffusion which smears away the hot/cold fluid interface. A related problem with standard codes is the inability to track plumes injected into the liquid flow, again due to numerical diffusion. The combined effects of buoyant stratification and plume dispersion have been identified as being important in operation of the Supplementary Safety System which injects neutron-poison ink into SRS reactors to provide safe shutdown in the event of safety rod failure. The MODFLOW code discussed here provides transient moderator flow pattern information with stratification effects, and tracks the location of ink plumes in the reactor. The code, written in Fortran, is compiled for Macintosh II computers, and includes subroutines for interactive control and graphical output. Removing the graphics capabilities, the code can also be compiled on other computers. With graphics, in addition to the capability to perform safety related computations, MODFLOW also provides an easy tool for becoming familiar with flow distributions in SRS reactors.

  7. Flood moderation: Declining peak flows along some Rocky Mountain rivers and the underlying mechanism

    NASA Astrophysics Data System (ADS)

    Rood, Stewart B.; Foster, Stephen G.; Hillman, Evan J.; Luek, Andreas; Zanewich, Karen P.

    2016-05-01

    It has been proposed that global warming will amplify the water cycle and intensify river floods. We tested this hypothesis by investigating historic trends in magnitudes, durations and timing of the annual peak flows of rivers that drain the Rocky Mountains around the North American hydrographic apex, the source for rivers flowing to the Pacific, Arctic (including Hudson Bay) and Atlantic Oceans. We sought century-long records and to reduce influences from land-use we assessed drainages from parks and protected areas. Of 30 rivers and reaches that were free-flowing or slightly regulated, seven displayed declining peak flows (7 p < 0.1, 4 p < 0.05), and one showed increase (p < 0.05); three of five moderately regulated rivers displayed decline (p < 0.05). Substantial floods, exceeding the 1-in-5 year recurrence (Q5), were more common in the early versus latter halves of the records for some Arctic drainages and were more common during the Pacific Decadal Oscillation negative phase for all regions. The timing of peak flows was relatively unchanged and Q5 flood durations declined for a few rivers. These results indicate flood moderation rather than flood intensification, particularly for Arctic Ocean drainages. This could reflect regional hydrological consequences from climate change including: (1) declining overall annual river flows; (2) winter warming that would increase the rain versus snow proportion, thus reducing snow accumulation and melt; and (3) spring warming that advances snow melt, lengthening the melt interval before peak flows. These changes would shift the seasonality of river flows and reduce annual peaks. We might expect continuing moderation of peak flows but there will probably still be occasional major floods from exceptional rain events such as occurred in northern Montana in 1964 and in southern Alberta in 2013.

  8. Linearized numerical solution method for rotating coaxial disk flows at moderate Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Wu, J.; Delgado, A.; Rath, H. J.

    A linearized solution method for rotating coaxial disk flows at moderate Reynolds numbers is discussed below. The analytical or numerical linearized similarity solutions agree with the nonlinear ones for infinite disk flows of the Stewartson-type as well as of the Batchelor-type with a small difference between angular velocities of both the disks. Over the inner portion of shrouded flows the computed results of the linearized partial differential equations have, overall, a good agreement with the solutions of the nonlinear von Karman similarity one and also with the complete Navier-Stokes solution.

  9. Convective heat flow in space cryogenics plugs - Critical and moderate He II heat flux densities

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Frederking, T. H. K.

    1990-01-01

    Plug flow rates of entropy, heat and normal fluid in phase separators and in zero net mass flow systems are, to some extent, quite similar. A simplified analysis of critical conditions is presented in agreement with data trends. A critical temperature gradient arises on the basis of the He II two-fluid model at the stability limit constraining the thermohydrodynamics of the system. Thus, the question of critical thermodynamic fluctuations associated with nucleation versus the possibility of critical gradients in externally imposed parameters is answered in favor of the latter route toward turbulence. Furthermore, a similarity equation is presented which incorporates size dependent rates for moderate heat flow densities observed in experiments.

  10. Turbulent bands in plane-Poiseuille flow at moderate Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Xiong, Xiangming; Tao, Jianjun; Chen, Shiyi; Brandt, Luca

    2015-04-01

    In this letter, we show via numerical simulations that the typical flow structures appearing in transitional channel flows at moderate Reynolds numbers are not spots but isolated turbulent bands, which have much longer lifetimes than the spots. Localized perturbations can evolve into isolated turbulent bands by continuously growing obliquely when the Reynolds number is larger than 660. However, interactions with other bands and local perturbations cause band breaking and decay. The competition between the band extension and breaking does not lead to a sustained turbulence until Re becomes larger than about 1000. Above this critical value, the bands split, providing an effective mechanism for turbulence spreading.

  11. Low blood flow at onset of moderate-intensity exercise does not limit muscle oxygen uptake.

    PubMed

    Nyberg, Michael; Mortensen, Stefan P; Saltin, Bengt; Hellsten, Ylva; Bangsbo, Jens

    2010-03-01

    The effect of low blood flow at onset of moderate-intensity exercise on the rate of rise in muscle oxygen uptake was examined. Seven male subjects performed a 3.5-min one-legged knee-extensor exercise bout (24 +/- 1 W, mean +/- SD) without (Con) and with (double blockade; DB) arterial infusion of inhibitors of nitric oxide synthase (N(G)-monomethyl-l-arginine) and cyclooxygenase (indomethacin) to inhibit the synthesis of nitric oxide and prostanoids, respectively. Leg blood flow and leg oxygen delivery throughout exercise was 25-50% lower (P < 0.05) in DB compared with Con. Leg oxygen extraction (arteriovenous O(2) difference) was higher (P < 0.05) in DB than in Con (5 s: 127 +/- 3 vs. 56 +/- 4 ml/l), and leg oxygen uptake was not different between Con and DB during exercise. The difference between leg oxygen delivery and leg oxygen uptake was smaller (P < 0.05) during exercise in DB than in Con (5 s: 59 +/- 12 vs. 262 +/- 39 ml/min). The present data demonstrate that muscle blood flow and oxygen delivery can be markedly reduced without affecting muscle oxygen uptake in the initial phase of moderate-intensity exercise, suggesting that blood flow does not limit muscle oxygen uptake at the onset of exercise. Additionally, prostanoids and/or nitric oxide appear to play important roles in elevating skeletal muscle blood flow in the initial phase of exercise.

  12. Gas flow meter and method for measuring gas flow rate

    DOEpatents

    Robertson, Eric P.

    2006-08-01

    A gas flow rate meter includes an upstream line and two chambers having substantially equal, fixed volumes. An adjustable valve may direct the gas flow through the upstream line to either of the two chambers. A pressure monitoring device may be configured to prompt valve adjustments, directing the gas flow to an alternate chamber each time a pre-set pressure in the upstream line is reached. A method of measuring the gas flow rate measures the time required for the pressure in the upstream line to reach the pre-set pressure. The volume of the chamber and upstream line are known and fixed, thus the time required for the increase in pressure may be used to determine the flow rate of the gas. Another method of measuring the gas flow rate uses two pressure measurements of a fixed volume, taken at different times, to determine the flow rate of the gas.

  13. Models for Turbulent Plane Couette Flow Using the Proper Orthogonal Decomposition: Moderate Aspect Ratio Domain

    NASA Astrophysics Data System (ADS)

    Moehlis, Jeff; Smith, Troy; Holmes, Philip; Faisst, Holger

    2002-11-01

    We model turbulent plane Couette flow for a moderate aspect ratio domain by expanding the velocity field as a sum of optimal modes calculated via the proper orthogonal decomposition from numerical data. Ordinary differential equations are obtained by Galerkin projection of the Navier-Stokes equations onto these modes. For a minimal truncation including only the most energetic modes having no streamwise variation, we show under quite general conditions the existence of linearly stable nontrivial fixed points, corresponding to a state in which the mean flow is coupled to streamwise vortices and their associated streaks. When the two next most energetic modes, still lacking streamwise variations, are included, chaos and heteroclinic cycles associated with the fixed points are found. The attractors involve repeated visits near unstable fixed points and periodic orbits corresponding to steady and periodically varying vortices, and account for a self-sustaining process in which vortices interact with the mean flow.

  14. Underestimation of access flow by ultrasound dilution flow measurements

    NASA Astrophysics Data System (ADS)

    Bos, Clemens; Smits, Johannes H. M.; Zijlstra, Jan J.; Blankestijn, Peter J.; Bakker, Chris J. G.; Viergever, Max A.

    2002-02-01

    For hemodialysis access surveillance, flow measurements are increasingly considered important because they identify accesses at risk of thrombosis. Usually these flow measurements are performed with the ultrasound dilution technique. In a previous patient study it was observed that the resulting flow values were systematically low as compared to magnetic resonance flow measurements, but a satisfactory explanation was lacking. In the present study, we will demonstrate by hemodynamic calculations and in vitro experiments that this discrepancy can be explained by a temporary reduction of the access flow rate, caused by the reversed needle configuration during ultrasound dilution flow measurements. In this configuration, blood is injected retrogressively at one needle and flow between the needles is increased, causing an increased dissipation of energy. The proposed explanation is subsequently confirmed in a patient with a loop graft, by measuring the blood velocity by Doppler ultrasound as a function of reversed dialyzer flow rate. Apart from the ultrasound dilution technique, these findings are applicable to other recently proposed methods for measuring access flow that employ the reversed needle configuration.

  15. Method and device for measuring fluid flow

    DOEpatents

    Atherton, Richard; Marinkovich, Phillip S.; Spadaro, Peter R.; Stout, J. Wilson

    1976-11-23

    This invention is a fluid flow measuring device for determining the coolant flow at the entrance to a specific nuclear reactor fuel region. The device comprises a plurality of venturis having the upstream inlet and throat pressure of each respectively manifolded together to provide one static pressure signal for each region monitored. The device provides accurate flow measurement with low pressure losses and uniform entrance and discharge flow distribution.

  16. Blood flow and muscle oxygenation during low, moderate, and maximal sustained isometric contractions.

    PubMed

    McNeil, Chris J; Allen, Matti D; Olympico, Eric; Shoemaker, J Kevin; Rice, Charles L

    2015-09-01

    A reduction of blood flow to active muscle will precipitate fatigue, and sustained isometric contractions produce intramuscular and compartmental pressures that can limit flow. The present study explored how blood flow and muscle oxygenation respond to isometric contractions at low, moderate, and maximal intensities. Over two visits, 10 males (26 ± 2 yr; means ± SD) performed 1-min dorsiflexion contractions at 30, 60, and 100% of maximal voluntary contraction (MVC) torque. Doppler ultrasound of the anterior tibial artery was used to record arterial diameter and mean blood velocity and to calculate absolute blood flow. The tissue oxygenation index (TOI) of tibialis anterior was acquired with near-infrared spectroscopy (NIRS). There was a progressive increase in blood flow at 30% MVC (peak of 289 ± 139% resting value), no change from rest until an increase in the final 10 s of exercise at 60% MVC (peak of 197 ± 102% rest), and an initial decrease (59 ± 30% resting value) followed by a progressive increase at 100% MVC (peak of 355 ± 133% rest). Blood flow was greater at 30 and 100% than 60% MVC during the last 30 s of exercise. TOI was ∼63% at rest and, within 30 s of exercise, reached steady-state values of ∼42%, ∼22%, and ∼22% for 30, 60, and 100% MVC, respectively. Even maximal contraction of the dorsiflexors is unable to cause more than a transient decrease of flow in the anterior tibial artery. Unlike dynamic or intermittent isometric exercise, our results indicate blood flow is not linearly graded with intensity or directly coupled with oxygenation during sustained isometric contractions.

  17. LES of Separated Flows Over an Airfoil at Moderate Reynolds Numbers

    NASA Astrophysics Data System (ADS)

    Castiglioni, G.; Domaradzki, J. A.; Grilli, M.; Hickel, S.

    2012-11-01

    Separation effects strongly affect flows for unmanned aerial vehicles, micro air vehicles, and rotating machinery, e.g., wind turbines, propellers, and low pressure turbines. The Reynolds number for such flows are usually moderate and they can be accurately simulated using DNS. However, the large computational cost of DNS makes this technique unsuitable for industrial applications while less expensive RANS and LES techniques encounter difficulties in simulating such flows because they consist of a mixture of laminar, separated, transitional, and turbulent regions. In this work we investigate an ability of LES to accurately predict the behavior of such flows on a benchmark case of a laminar separation bubble on a NACA-0012 airfoil at Rec = 5 ×104 at 5 deg of incidence for which accurate DNS results are available (Jones et al., JFM 602, 175 (2008)). Using a conservative immersed boundary method with the Adaptive Local Deconvolution Method (ALDM) we have performed 2D and 3D simulations of this flow with resolution reduced drastically from that in the benchmark DNS. The results to date show good predictions for the pressure coefficient Cp and the location of the separation point, but the friction coefficient Cf is not predicted accurately. Work performed during TTR40 Summer Program 2011.

  18. The Leicestershire Intellectual Disability Tool: A Simple Measure to Identify Moderate to Profound Intellectual Disability

    ERIC Educational Resources Information Center

    Tyrer, Freya; McGrother, Catherine W.; Thorp, Catherine F.; Taub, Nicholas A.; Bhaumik, Sabyasachi; Cicchetti, Domenic V.

    2008-01-01

    Background: It is often useful to ascertain whether adults have moderate to profound intellectual disability (approximate IQ less than 50; developmental age less than 108 months) when deciding whether to refer to specialist or mainstream services. The aim of the present study was to develop a simple measure to estimate moderate to profound…

  19. COTS MEMS Flow-Measurement Probes

    NASA Technical Reports Server (NTRS)

    Redding, Chip; Smith, Floyd A.; Blank, Greg; Cruzan, Charles

    2004-01-01

    As an alternative to conventional tubing instrumentation for measuring airflow, designers and technicians at Glenn Research Center have been fabricating packaging components and assembling a set of unique probes that contain commercial off-the-shelf (COTS) microelectromechanical systems (MEMS) sensor chips. MEMS sensor chips offer some compelling advantages over standard macroscopic measurement devices. MEMS sensor technology has matured through mass production and use in the automotive and aircraft industries. At present, MEMS are the devices of choice for sensors in such applications as tire-pressure monitors, altimeters, pneumatic controls, cable leak detectors, and consumer appliances. Compactness, minimality of power demand, rugged construction, and moderate cost all contribute to making MEMS sensors attractive for instrumentation for future research. Conventional macroscopic flow-measurement instrumentation includes tubes buried beneath the aerodynamic surfaces of wind-tunnel models or in wind-tunnel walls. Pressure is introduced at the opening of each such tube. The pressure must then travel along the tube before reaching a transducer that generates an electronic signal. The lengths of such tubes typically range from 20 ft (approx.= 6 m) to hundreds of feet (of the order of 100 m). The propagation of pressure signals in the tubes damps the signals considerably and makes it necessary to delay measurements until after test rigs have reached steady-state operation. In contrast, a MEMS pressure sensor that generates electronic output can take readings continuously under dynamic conditions in nearly real time. In order to use stainless-steel tubing for pressure measurements, it is necessary to clean many tubes, cut them to length, carefully install them, delicately deburr them, and splice them. A cluster of a few hundred 1/16-in.- (approx.=1.6-mm-) diameter tubes (such clusters are common in research testing facilities) can be several inches (of the order of 10

  20. Achromatic Emission Velocity Measurements in Luminous Flows

    NASA Technical Reports Server (NTRS)

    Schneider, S. J.; Fulghum, S. F.; Rostler, P. S.

    1997-01-01

    A new velocity measurement instrument for luminous flows was developed by Science Research Laboratory for NASA. The SIEVE (Segmented Image Emission VElocimeter) instrument uses broadband light emitted by the flow for the velocity measurement. This differs from other velocimetry techniques in that it does not depend on laser illumination and/or light scattering from particles in the flow. The SIEVE is a passive, non-intrusive diagnostic. By moving and adjusting the imaging optics, the SIEVE can provide three-dimensional mapping of a flow field and determine turbulence scale size. A SIEVE instrument was demonstrated on an illuminated rotating disk to evaluate instrument response and noise and on an oxy-acetylene torch to measure flame velocities. The luminous flow in rocket combustors and plumes is an ideal subject for the SIEVE velocity measurement technique.

  1. Influence of moderate Joule heating on electroosmotic flow velocity, retention, and efficiency in capillary electrochromatography.

    PubMed

    Chen, Guofang; Tallarek, Ulrich; Seidel-Morgenstern, Andreas; Zhang, Yukui

    2004-07-30

    The influence of Joule heating on electroosmotic flow velocity, the retention factor of neutral analytes, and separation efficiency in capillary electrochromatography was investigated theoretically and experimentally. A plot of electrical current against the applied electrical field strength was used to evaluate the Joule heating effect. When the mobile phase concentration of Tris buffer exceeded 5.0 mM in the studied capillary electrochromatography systems using particulate and monolithic columns (with an accompanying power level of heat dissipation higher than 0.35 W/m), the Joule heating effect became clearly noticeable. Theoretical models for describing the variation of electroosmotic flow velocity with increasing applied field strength and the change of retention factors for neutral analytes with electrical field strength at higher Tris buffer concentrations were analyzed to explain consequences of Joule heating in capillary electrochromatography. Qualitative agreement between experimental data and implications of the theoretical model analysis was observed. The decrease of separation efficiency in capillary electrochromatography with macroporous octadecylsilica particles at high buffer concentration can be also attributed to Joule heating mainly via the increased axial diffusion of the analyte molecules and dispersion of solute bands by a nonuniform electroosmotic flow profile over the column cross-section. However, within a moderate temperature range, the contribution of the macroscopic velocity profile in the column arising from radial temperature gradients is insignificant.

  2. Flow Disturbance Characterization Measurements in the National Transonic Facility

    NASA Technical Reports Server (NTRS)

    King, Rudolph A.; Andino, Marlyn Y.; Melton, Latunia; Eppink, Jenna; Kegerise, Michael A.; Tsoi, Andrew

    2012-01-01

    Recent flow measurements have been acquired in the National Transonic Facility (NTF) to assess the unsteady flow environment in the test section. The primary purpose of the test is to determine the feasibility of the NTF to conduct laminar-flow-control testing and boundary-layer transition sensitive testing. The NTF can operate in two modes, warm (air) and cold/cryogenic (nitrogen) test conditions for testing full and semispan scaled models. The warm-air mode enables low to moderately high Reynolds numbers through the use of high tunnel pressure, and the nitrogen mode enables high Reynolds numbers up to flight conditions, depending on aircraft type and size, utilizing high tunnel pressure and cryogenic temperatures. NASA's Environmentally Responsible Aviation (ERA) project is interested in demonstrating different laminar-flow technologies at flight-relevant operating conditions throughout the transonic Mach number range and the NTF is well suited for the initial ground-based demonstrations. Roll polar data at selected test conditions were obtained to look at the uniformity of the flow disturbance field in the test section. Data acquired from the rake probes included mean total temperatures, mean and fluctuating static/total pressures, and mean and fluctuating hot-wire measurements. . Based on the current measurements and previous data, an assessment was made that the NTF is a suitable facility for ground-based demonstrations of laminar-flow technologies at flight-relevant conditions in the cryogenic mode.

  3. LEFT VENTRICULAR DYSSYNCHRONY IN PATIENTS WITH MODERATE CORONARY STENOSIS AND BORDER LINE FRACTIONAL FLOW RESERVE

    PubMed Central

    SHIBATA, YOHEI; SONE, TAKAHITO; TSUBOI, HIDEYUKI; ISOBE, SATOSHI; ISHII, HIDEKI; SUZUKI, SUSUMU; HAYASHI, MUTSUHARU; MUROHARA, TOYOAKI

    2015-01-01

    ABSTRACT The cutoff values of fractional flow reserve (FFR) to detect physiological myocardial ischemia are still controversial. Some studies have reported that left ventricular (LV) dyssynchrony occurs in patients with coronary artery disease (CAD). The purpose of this study was to investigate LV dyssynchrony in patients with moderate coronary stenosis and borderline FFR, using stress electrocardiographically-gated myocardial perfusion single-photon emission computed tomography (SPECT). The study population comprised 10 patients with moderate (50–75% diameter) stenosis and an FFR in the range 0.75–0.90, who were compared to 10 control subjects. All underwent stress myocardial 99mTc-sestamibi (MIBI) or tetrofosmin SPECT imaging. The regional time to end systole (TES), time to peak ejection (TPE), and time to peak filling (TPF) were obtained as indexes of perfusion and function, using gated SPECT (pFAST) in combination with Cardio Gated SPECT Regional Assessment for LV Function (cardioGRAF). The dyssynchrony index (DI) was also calculated. The DI of post-stress TES was significantly greater than that of rest in patients with moderate CAD (4.8 ± 2.8 vs. 2.7 ± 1.5, P = 0.01), but there were no significant differences in the control subjects (3.0 ± 1.7 vs. 2.9 ± 1.9, P = 0.99). There were no significant differences in TPE and TPF between the groups. In conclusion, LV dyssynchrony may occur after stress in patients with coronary stenosis and borderline FFR, even without a significant reduction in perfusion. PMID:25797980

  4. Multipath ultrasonic flow meters for gas measurement

    SciTech Connect

    Saunders, M.P.

    1995-11-01

    This paper gives an introduction to the practical application of ultrasonic gas flow meters. A general outline of the theory and methods applied using multipath flow meters. The multi-path type meter provides state of the art gas flow measurements and its accuracy and reliability satisfy the requirements for custody transfer. A typical multi-path device can achieve accuracies better than 0.2%.

  5. Quantitative tomographic measurements of opaque multiphase flows

    SciTech Connect

    GEORGE,DARIN L.; TORCZYNSKI,JOHN R.; SHOLLENBERGER,KIM ANN; O'HERN,TIMOTHY J.; CECCIO,STEVEN L.

    2000-03-01

    An electrical-impedance tomography (EIT) system has been developed for quantitative measurements of radial phase distribution profiles in two-phase and three-phase vertical column flows. The EIT system is described along with the computer algorithm used for reconstructing phase volume fraction profiles. EIT measurements were validated by comparison with a gamma-densitometry tomography (GDT) system. The EIT system was used to accurately measure average solid volume fractions up to 0.05 in solid-liquid flows, and radial gas volume fraction profiles in gas-liquid flows with gas volume fractions up to 0.15. In both flows, average phase volume fractions and radial volume fraction profiles from GDT and EIT were in good agreement. A minor modification to the formula used to relate conductivity data to phase volume fractions was found to improve agreement between the methods. GDT and EIT were then applied together to simultaneously measure the solid, liquid, and gas radial distributions within several vertical three-phase flows. For average solid volume fractions up to 0.30, the gas distribution for each gas flow rate was approximately independent of the amount of solids in the column. Measurements made with this EIT system demonstrate that EIT may be used successfully for noninvasive, quantitative measurements of dispersed multiphase flows.

  6. Perspectives of anisotropic flow measurements at NICA

    NASA Astrophysics Data System (ADS)

    Korotkikh, V. L.; Lokhtin, I. P.; Malinina, L. V.; Petrushanko, S. V.; Snigirev, A. M.

    2016-08-01

    High-accuracy and high-luminosity measurements of anisotropic flow for various hadron types over full NICA energy range will provide important constraints on the early dynamics of heavy-ion reactions under the conditions where a first-order quark-hadron phase transition may occur. The statistical reach for elliptic flow measurements at NICA is estimated with HYDJET++ heavy-ion event generator.

  7. Ultrasonic rate measurement of multiphase flow

    SciTech Connect

    Dannert, D.A.; Horne, R.N.

    1993-01-01

    On 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 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. This 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. It has many advantages besides the ones previously mentioned and is in full in that chapter.

  8. Measurement of kinematically unstationary separated flows

    NASA Astrophysics Data System (ADS)

    Poensgen, C. A.; Gallus, H. E.

    The development of flow separation between the hub wall and the blade suction side in an axial compressor annular cascade is examined with several measurement techniques. The flow was first assumed to be stationary; separation could be estimated with flow visualization and pneumatic pressure measurements on lateral walls and blade surfaces were carried out for evaluating flow losses in the cascade. Measurements at airfoil surfaces with hot wire probes and hot film sensors gave information about the development of the blade boundary layer. The influence of the unstationary flow on the development of airfoil boundary layers and the separation at the hub with dependence of the aerodynamic loading is studied. Cylindrical bars were used instead of a real blading in order to obtain typical wakes without potential interactions between rotor and stator. Experimental examinations similar to the one described for the steady flow were carried out. It is found that flow losses increase in the airfoil boundary layer while they drop to the hub separation. By and large, the total losses are found to be lower with unsteady flow.

  9. Flowing dusty plasma experiments: generation of flow and measurement techniques

    NASA Astrophysics Data System (ADS)

    Jaiswal, S.; Bandyopadhyay, P.; Sen, A.

    2016-12-01

    A variety of experimental techniques for the generation of subsonic/supersonic dust fluid flows and means of measuring such flow velocities are presented. The experiments have been carried out in a \\Pi -shaped dusty plasma experimental device with micron size kaolin/melamine formaldehyde particles embedded in a background of argon plasma created by a direct current glow discharge. A stationary dust cloud is formed over the cathode region by precisely balancing the pumping speed and gas flow rate. A flow of dust particles/fluid is generated by additional gas injection from a single or dual locations or by altering the dust confining potential. The flow velocity is then estimated by three different techniques, namely, by super particle identification code, particle image velocimetry analysis and the excitation of dust acoustic waves. The results obtained from these three different techniques along with their merits and demerits are discussed. An estimation of the neutral drag force responsible for the generation as well as the attenuation of the dust fluid flow is made. These techniques can be usefully employed in laboratory devices to investigate linear and non-linear collective excitations in a flowing dusty plasma.

  10. Measurements of gravity driven granular channel flows

    NASA Astrophysics Data System (ADS)

    Facto, Kevin

    This dissertation presents experiments that studied two gravity driven granular channel flows. The first experiment used magnetic resonance imaging to measure the density and displacement distributions of poppy seeds flowing in a rough walled channel. Time-averaged measurements of normalized velocity and density showed little flow speed dependence. Instantaneous measurements, however, showed marked velocity dependence in the displacement distributions. There was evidence of aperiodic starting and stopping at lower flow speeds and the onset of density waves on a continuous flow at higher speeds. The second experiment measured forces in all three spatial directions at the boundary of a flow of steel balls. The relationship between the normal and the tangential forces were examined statistically and compared to the Coulomb friction model. For both large and small forces, the tangential and normal forces are unrelated, as there appears to be a strong tendency for the tangential force to maintain a value that will bear the weight the weight of the particles in flow.

  11. Direct numerical simulation of moderate-Reynolds-number flow past arrays of rotating spheres

    NASA Astrophysics Data System (ADS)

    Zhou, Qiang; Fan, Liang-Shih

    2015-07-01

    Direct numerical simulations with an immersed boundary-lattice Boltzmann method are used to investigate the effects of particle rotation on flows past random arrays of mono-disperse spheres at moderate particle Reynolds numbers. This study is an extension of a previous study of the authors [Q. Zhou and L.-S. Fan, "Direct numerical simulation of low-Reynolds-number flow past arrays of rotating spheres," J. Fluid Mech. 765, 396-423 (2015)] that explored the effects of particle rotation at low particle Reynolds numbers. The results of this study indicate that as the particle Reynolds number increases, the normalized Magnus lift force decreases rapidly when the particle Reynolds number is in the range lower than 50. For the particle Reynolds number greater than 50, the normalized Magnus lift force approaches a constant value that is invariant with solid volume fractions. The proportional dependence of the Magnus lift force on the rotational Reynolds number (based on the angular velocity and the diameter of the spheres) observed at low particle Reynolds numbers does not change in the present study, making the Magnus lift force another possible factor that can significantly affect the overall dynamics of fluid-particle flows other than the drag force. Moreover, it is found that both the normalized drag force and the normalized torque increase with the increase of the particle Reynolds number and the solid volume fraction. Finally, correlations for the drag force, the Magnus lift force, and the torque in random arrays of rotating spheres at arbitrary solids volume fractions, rotational Reynolds numbers, and particle Reynolds numbers are formulated.

  12. Pancreatic islet blood flow and its measurement.

    PubMed

    Jansson, Leif; Barbu, Andreea; Bodin, Birgitta; Drott, Carl Johan; Espes, Daniel; Gao, Xiang; Grapensparr, Liza; Källskog, Örjan; Lau, Joey; Liljebäck, Hanna; Palm, Fredrik; Quach, My; Sandberg, Monica; Strömberg, Victoria; Ullsten, Sara; Carlsson, Per-Ola

    2016-05-01

    Pancreatic islets are richly vascularized, and islet blood vessels are uniquely adapted to maintain and support the internal milieu of the islets favoring normal endocrine function. Islet blood flow is normally very high compared with that to the exocrine pancreas and is autonomously regulated through complex interactions between the nervous system, metabolites from insulin secreting β-cells, endothelium-derived mediators, and hormones. The islet blood flow is normally coupled to the needs for insulin release and is usually disturbed during glucose intolerance and overt diabetes. The present review provides a brief background on islet vascular function and especially focuses on available techniques to measure islet blood perfusion. The gold standard for islet blood flow measurements in experimental animals is the microsphere technique, and its advantages and disadvantages will be discussed. In humans there are still no methods to measure islet blood flow selectively, but new developments in radiological techniques hold great hopes for the future.

  13. NMRI Measurements of Flow of Granular Mixtures

    NASA Technical Reports Server (NTRS)

    Nakagawa, Masami; Waggoner, R. Allen; Fukushima, Eiichi

    1996-01-01

    We investigate complex 3D behavior of granular mixtures in shaking and shearing devices. NMRI can non-invasively measure concentration, velocity, and velocity fluctuations of flows of suitable particles. We investigate origins of wall-shear induced convection flow of single component particles by measuring the flow and fluctuating motion of particles near rough boundaries. We also investigate if a mixture of different size particles segregate into their own species under the influence of external shaking and shearing disturbances. These non-invasive measurements will reveal true nature of convecting flow properties and wall disturbance. For experiments in a reduced gravity environment, we will design a light weight NMR imager. The proof of principle development will prepare for the construction of a complete spaceborne system to perform experiments in space.

  14. Pancreatic islet blood flow and its measurement

    PubMed Central

    Jansson, Leif; Barbu, Andreea; Bodin, Birgitta; Drott, Carl Johan; Espes, Daniel; Gao, Xiang; Grapensparr, Liza; Källskog, Örjan; Lau, Joey; Liljebäck, Hanna; Palm, Fredrik; Quach, My; Sandberg, Monica; Strömberg, Victoria; Ullsten, Sara; Carlsson, Per-Ola

    2016-01-01

    Pancreatic islets are richly vascularized, and islet blood vessels are uniquely adapted to maintain and support the internal milieu of the islets favoring normal endocrine function. Islet blood flow is normally very high compared with that to the exocrine pancreas and is autonomously regulated through complex interactions between the nervous system, metabolites from insulin secreting β-cells, endothelium-derived mediators, and hormones. The islet blood flow is normally coupled to the needs for insulin release and is usually disturbed during glucose intolerance and overt diabetes. The present review provides a brief background on islet vascular function and especially focuses on available techniques to measure islet blood perfusion. The gold standard for islet blood flow measurements in experimental animals is the microsphere technique, and its advantages and disadvantages will be discussed. In humans there are still no methods to measure islet blood flow selectively, but new developments in radiological techniques hold great hopes for the future. PMID:27124642

  15. Unsteady measurement techniques for turbomachinery flows

    NASA Astrophysics Data System (ADS)

    Jaffa, Nicholas Andrew

    Accurate unsteady measurements are required for studying the flows in high speed turbomachines, which rely on the interaction between rotating and stationary components. Using statistics of phase locked ensembles simplifies the problem, but accurate frequency response in the 10-100 kHz range significantly limits the applicable techniques. This research advances the state of the art for phase resolved measurement techniques using for high speed turbomachinery flows focusing on the following areas: development, validation, and uncertainty quantification. Four methods were developed and implemented: an unsteady total pressure probe, the multiple overheat hot-wire method, the slanted hot-wire method, and the phase peak yaw hot-wire method. These methods allow for the entire phase locked average flow field to be measured (temperature, pressure, and velocity components, swirl angle, etc.). No trusted reference measurement or representative canonical flow exists for comparison of the phase resolved quantities, making validation challenging. Five different validation exercises were performed to increase the confidence and explore the range of applicability. These exercises relied on checking for consistency with expected flow features, comparing independent measurements, and cross validation with CFD. The combined uncertainties for the measurements were quantified using uncertainty estimates from investigations into the elemental error sources. The frequency response uncertainty of constant temperature hot-wire system was investigated using a novel method of illuminating the wire with a laser pulse. The uncertainty analysis provided estimates for the uncertainty in the measurements as well as showing the sensitivity to various sources of error.

  16. Attitude importance as a moderator of the relationship between implicit and explicit attitude measures.

    PubMed

    Karpinski, Andrew; Steinman, Ross B; Hilton, James L

    2005-07-01

    The authors examined attitude importance as a moderator of the relationship between the Implicit Association Test (IAT) and explicit attitude measures. In Study 1 (N = 194), as ratings of attitude importance regarding the 2000 presidential election increased, the strength of the relationship between a Bush-Gore IAT and explicit attitude measures also increased. Study 2 provided a conceptual replication of these results using attitudes toward Coke and Pepsi (N = 112). In addition, across both studies, explicit attitude measures were better predictors of deliberative behaviors than IAT scores. In Study 3 (N = 77), the authors examined the role of elaboration as a mechanism by which attitude importance may moderate IAT-explicit attitude correlations. As predicted, increased elaboration resulted in stronger IAT-explicit attitude correlations. Other possible mechanisms by which attitude importance may moderate the IAT-explicit attitude relationship also are discussed.

  17. Spectroscopic Measurement Techniques for Aerospace Flows

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; Bathel, Brett F.; Johansen, Craig T.; Cutler, Andrew D.; Hurley, Samantha

    2014-01-01

    The conditions that characterize aerospace flows are so varied, that a single diagnostic technique is not sufficient for its measurement. Fluid dynamists use knowledge of similarity to help categorize and focus on different flow conditions. For example, the Reynolds number represents the ratio of inertial to viscous forces in a flow. When the velocity scales, length scales, and gas density are large and the magnitude of the molecular viscosity is low, the Reynolds number becomes large. This corresponds to large scale vehicles (e.g Airbus A380), fast moving objects (e.g. artillery projectiles), vehicles in dense fluids (e.g. submarine in water), or flows with low dynamic viscosity (e.g. skydiver in air). In each of these cases, the inertial forces dominate viscous forces, and unsteady turbulent fluctuations in the flow variables are observed. In contrast, flows with small length scales (e.g. dispersion of micro-particles in a solid rocket nozzle), slow moving objects (e.g. micro aerial vehicles), flows with low density gases (e.g. atmospheric re-entry), or fluids with a large magnitude of viscosity (e.g. engine coolant flow), all have low Reynolds numbers. In these cases, viscous forces become very important and often the flows can be steady and laminar. The Mach number, which is the ratio of the velocity to the speed of sound in the medium, also helps to differentiate types of flows. At very low Mach numbers, acoustic waves travel much faster than the object, and the flow can be assumed to be incompressible (e.g. Cessna 172 aircraft). As the object speed approaches the speed of sound, the gas density can become variable (e.g. flow over wing of Learjet 85). When the object speed is higher than the speed of sound (Ma > 1), the presences of shock waves and other gas dynamic features can become important to the vehicle performance (e.g. SR-71 Blackbird). In the hypersonic flow regime (Ma > 5), large changes in temperature begin to affect flow properties, causing real

  18. PERFORMING QUALITY FLOW MEASUREMENTS AT MINE SITES

    EPA Science Inventory

    Accurate flow measurement data is vital to research, monitoring, and remediation efforts at mining sites. This guidebook has been prepared to provide a summary of information relating to the performance of low measurements, and how this information can be applied at mining sites....

  19. Wastewater Sampling Methodologies and Flow Measurement Techniques.

    ERIC Educational Resources Information Center

    Harris, Daniel J.; Keffer, William J.

    This document provides a ready source of information about water/wastewater sampling activities using various commercial sampling and flow measurement devices. The report consolidates the findings and summarizes the activities, experiences, sampling methods, and field measurement techniques conducted by the Environmental Protection Agency (EPA),…

  20. Respirator Filter Efficiency Testing Against Particulate and Biological Aerosols Under Moderate to High Flow Rates

    DTIC Science & Technology

    2006-08-01

    stopped and the filter removed from the system for analysis. Polonium - 210 static eliminators were used to minimize particle loss during transport to...may provide a considerable overestimate of filter performance. Brosseau et al. (1990) compared the collection of silica and asbestos aerosols by DM...a half times as great as that measured under steady flow conditions, which is consistent with the results of Stafford et al. (1973). The asbestos

  1. Measurement technique developments for LBE flows

    NASA Astrophysics Data System (ADS)

    Buchenau, D.; Eckert, S.; Gerbeth, G.; Stieglitz, R.; Dierckx, M.

    2011-08-01

    We report on the development of measurement techniques for flows in lead-bismuth eutectic alloys (LBE). This paper covers the test results of newly developed contactless flow rate sensors as well as the development and test of the LIDAR technique for operational free surface level detection. The flow rate sensors are based on the flow-induced disturbance of an externally applied AC magnetic field which manifests itself by a modified amplitude or a modified phase of the AC field. Another concept of a force-free contactless flow meter uses a single cylindrical permanent magnet. The electromagnetic torque on the magnet caused by the liquid metal flow sets the magnet into rotation. The operation of those sensors has been demonstrated at liquid metal test loops for which comparative flow rate measurements are available, as well as at the LBE loops THESYS at KIT and WEBEXPIR at SCK-CEN. For the level detection a commercial LIDAR system was successfully tested at the WEBEXPIR facility in Mol and the THEADES loop in Karlsruhe.

  2. Depth selective acousto-optic flow measurement

    PubMed Central

    Tsalach, Adi; Schiffer, Zeev; Ratner, Eliahu; Breskin, Ilan; Zeitak, Reuven; Shechter, Revital; Balberg, Michal

    2015-01-01

    Optical based methods for non-invasive measurement of regional blood flow tend to incorrectly assess cerebral blood flow, due to contribution of extra-cerebral tissues to the obtained signal. We demonstrate that spectral analysis of phase-coded light signals, tagged by specific ultrasound patterns, enables differentiation of flow patterns at different depths. Validation of the model is conducted by Monte Carlo simulation. In-vitro experiments demonstrate good agreement with the simulations' results and provide a solid validation to depth discrimination ability. These results suggest that signal contamination originating from extra-cerebral tissue may be eliminated using spectral analysis of ultrasonically tagged light. PMID:26713201

  3. Production of microbubbles from axisymmetric flow focusing in the jetting regime for moderate Reynolds numbers.

    PubMed

    Vega, E J; Acero, A J; Montanero, J M; Herrada, M A; Gañán-Calvo, A M

    2014-06-01

    We analyze both experimentally and numerically the formation of microbubbles in the jetting regime reached when a moderately viscous liquid stream focuses a gaseous meniscus inside a converging micronozzle. If the total (stagnation) pressure of the injected gas current is fixed upstream, then there are certain conditions on which a quasisteady gas meniscus forms. The meniscus tip is sharpened by the liquid stream down to the gas molecular scale. On the other side, monodisperse collections of microbubbles can be steadily produced in the jetting regime if the feeding capillary is appropriately located inside the nozzle. In this case, the microbubble size depends on the feeding capillary position. The numerical simulations for an imposed gas flow rate show that a recirculation cell appears in the gaseous meniscus for low enough values of that parameter. The experiments allow one to conclude that the bubble pinch-off comprises two phases: (i) a stretching motion of the precursor jet where the neck radius versus the time before the pinch essentially follows a potential law, and (ii) a final stage where a very thin and slender gaseous thread forms and eventually breaks apart into a number of micron-sized bubbles. Because of the difference between the free surface and core velocities, the gaseous jet breakage differs substantially from that of liquid capillary jets and gives rise to bubbles with diameters much larger than those expected from the Rayleigh-type capillary instability. The dependency of the bubble diameter upon the flow-rate ratio agrees with the scaling law derived by A. M. Gañán-Calvo [Phys. Rev. E 69, 027301 (2004)], although a slight influence of the Reynolds number can be observed in our experiments.

  4. Measurements of gamma-ray dose from a moderated /sup 252/Cf source

    SciTech Connect

    McDonald, J.C.; Griffith, R.V.; Plato, P.; Miklos, J.

    1983-06-01

    The gamma-ray dose fraction from a moderated /sup 252/Cf source was determined by using three types of dosimetry systems. Measurements were carried out in air at a distance of 35 cm from the surface of the moderating sphere (50 cm from the source which is at the center of the sphere) to the geometrical center of each detector. The moderating sphere is 0.8-mm-thick stainless steel shell filled with D/sub 2/O and covered with 0.5 mm of cadmium. Measurements were also carried out with instruments and dosimeters positioned at the surface of a 40 cm x 40 cm x 15 cm plexiglass irradiation phantom whose front surface was also 35 cm from the surface of the moderating sphere. A-150 tissue-equivalent (TE) plastic ionization chambers and a TE proportional counter (TEPC) were used to measure tissue dose, from which the neutron dose equivalent was computed. The ratio of gamma-ray dose to the neutron dose equivalent was determined by using a relatively neutron-insensitive Geiger-Mueller (GM) counter and thermoluminescent dosimeters (TLD). In addition, the event-size spectrum measured by the TEPC was also used to compute the gamma-ray dose fraction. The average value for the ratio of gamma-ray dose to neutron dose equivalent was found to be 0.18 with an uncertainty of about +-18%.

  5. Moderate Physical Activity and Its Relationship to Select Measures of a Healthy Diet

    ERIC Educational Resources Information Center

    Blakely, Frank; Dunnagan, Tim; Haynes, George; Moore, Sylvia; Pelican, Suzanne

    2004-01-01

    In rural communities, physical activity may influence and predict nutritional behaviors. The purpose of this investigation was to determine if an individual's stage of participation in moderate physical activity was related to select measures of a healthy diet. Data were collected using a mail-in survey from a random sample conducted in the…

  6. Coherent Raman spectroscopy for supersonic flow measurments

    NASA Technical Reports Server (NTRS)

    She, C. Y.

    1986-01-01

    In collaboration with NASA/Langley Research Center, a truly nonintrusive and nonseeding method for measuring supersonic molecular flow parameters was proposed and developed at Colorado State University. The feasibility of this Raman Doppler Velocimetry (RDV), currently operated in a scanning mode, was demonstrated not only in a laboratory environment at Colorado State University, but also in a major wind tunnel at NASA/Langley Research Center. The research progress of the RDV development is summarized. In addition, methods of coherent Rayleigh-Brillouin spectroscopy and single-pulse coherent Raman spectroscopy are investigated, respectively, for measurements of high-pressure and turbulent flows.

  7. Slip length measurement of gas flow

    NASA Astrophysics Data System (ADS)

    Maali, Abdelhamid; Colin, Stéphane; Bhushan, Bharat

    2016-09-01

    In this paper, we present a review of the most important techniques used to measure the slip length of gas flow on isothermal surfaces. First, we present the famous Millikan experiment and then the rotating cylinder and spinning rotor gauge methods. Then, we describe the gas flow rate experiment, which is the most widely used technique to probe a confined gas and measure the slip. Finally, we present a promising technique using an atomic force microscope introduced recently to study the behavior of nanoscale confined gas.

  8. Fluid Flow Technology that Measures Up

    NASA Technical Reports Server (NTRS)

    2004-01-01

    From 1994 to 1996, NASA s Marshall Space Flight Center conducted a Center Director's Discretionary Fund research effort to apply artificial intelligence technologies to the health management of plant equipment and space propulsion systems. Through this effort, NASA established a business relationship with Quality Monitoring and Control (QMC), of Kingwood, Texas, to provide hardware modeling and artificial intelligence tools. Very detailed and accurate Space Shuttle Main Engine (SSME) analysis and algorithms were jointly created, which identified several missing, critical instrumentation needs for adequately evaluating the engine health status. One of the missing instruments was a liquid oxygen (LOX) flow measurement. This instrument was missing since the original SSME included a LOX turbine flow meter that failed during a ground test, resulting in considerable damage for NASA. New balanced flow meter technology addresses this need with robust, safe, and accurate flow metering hardware.

  9. Improved visualization of flow field measurements

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    1991-01-01

    A capability was developed that makes it possible to apply to measured flow field data the visualization tools developed to display numerical solutions for computational fluid dynamic problems. The measurement monitor surface (MMS) procedure was applied to the analysis of flow field measurements within a low aspect ratio transonic axial flow fan rotor obtained with 2-D laser anemometry. The procedure generates input for the visualization tools developed to display numerical solutions for computational fluid dynamics problems. The relative Mach number contour plots obtained by this method resemble the conventional contour plots obtained by more traditional methods. The results show that the MMS procedure can be used to generate input for the multidimensional processing and analysis tools developed for data from numerical flow field simulations. They show that an experimenter can apply the MMS procedure to his data and then use an interactive graphics program to display scalar quantities like the Mach number by profiles, carpet plots, contour lines, and surfaces using various colors. Also, flow directionality can be shown by display of vector fields and particle traces.

  10. Ultrasonic meters measure gas pipeline flow

    SciTech Connect

    1995-04-01

    New ultrasonic meters from Stork Ultrasonic Technologies, Houston are improving pipeline gas flow measurements, custody transfers, process gas flow measurements, and flare gas applications. The meters are easy to install, extremely accurate, and all feature realtime measurements. This meter (Gassonic 400) is designed for use in 8-in. to 64-in. gas pipelines and features a dual transducer device which uses the absolute digital travel time method of pulse transmission. Wide band piezoceramic transducers are used in this bi-directional, single bounce system which includes pulse verification and high-speed electronic processing by a central processing unit. Measuring values of this meter are obtained by direct digital measurement of travel time of each individual ultrasonic pulse which covers a pre-determined distance between two transducers inserted in the pipe wall. These transducers cause negligible flow restriction and absolute digital reference and excellent repeatability is possible without adjustment or re-calibration. Dozens of measurements can be processed so that average output values are updated every second during use. It is a field-programmable meter for variations in site parameters, presentation of service diagnostics, user selected velocity or quantity outputs, and has standard analog and digital interfaces. Also, it is suitable for swirl measurement or compensation. Since it relies on a reflection method, the ultrasonic meter allows easy, one-sided insertion and it is suitable for hot-tapping. This instrument is especially useful in gas blending stations, compressor control, leak detection, salt dome storage applications, pipeline balancing, and additive injection systems.

  11. Optical Air Flow Measurements in Flight

    NASA Technical Reports Server (NTRS)

    Bogue, Rodney K.; Jentink, Henk W.

    2004-01-01

    This document has been written to assist the flight-test engineer and researcher in using optical flow measurements in flight applications. The emphasis is on describing tradeoffs in system design to provide desired measurement performance as currently understood. Optical system components are discussed with examples that illustrate the issues. The document concludes with descriptions of optical measurement systems designed for a variety of applications including aeronautics research, airspeed measurement, and turbulence hazard detection. Theoretical discussion is minimized, but numerous references are provided to supply ample opportunity for the reader to understand the theoretical underpinning of optical concepts.

  12. Review of air flow measurement techniques

    SciTech Connect

    McWilliams, Jennifer

    2002-12-01

    Airflow measurement techniques are necessary to determine the most basic of indoor air quality questions: ''Is there enough fresh air to provide a healthy environment for the occupants of the building?'' This paper outlines airflow measurement techniques, but it does not make recommendations for techniques that should be used. The airflows that will be discussed are those within a room or zone, those between rooms or zones, such as through doorways (open or closed) or passive vents, those between the building and outdoors, and those through mechanical air distribution systems. Techniques that are highlighted include particle streak velocimetry, hot wire anemometry, fan pressurization (measuring flow at a given pressure), tracer gas, acoustic methods for leak size determination, the Delta Q test to determine duct leakage flows, and flow hood measurements. Because tracer gas techniques are widely used to measure airflow, this topic is broken down into sections as follows: decay, pulse injection, constant injection, constant concentration, passive sampling, and single and multiple gas measurements for multiple zones.

  13. Accelerating moderately stiff chemical kinetics in reactive-flow simulations using GPUs

    NASA Astrophysics Data System (ADS)

    Niemeyer, Kyle E.; Sung, Chih-Jen

    2014-01-01

    The chemical kinetics ODEs arising from operator-split reactive-flow simulations were solved on GPUs using explicit integration algorithms. Nonstiff chemical kinetics of a hydrogen oxidation mechanism (9 species and 38 irreversible reactions) were computed using the explicit fifth-order Runge-Kutta-Cash-Karp method, and the GPU-accelerated version performed faster than single- and six-core CPU versions by factors of 126 and 25, respectively, for 524,288 ODEs. Moderately stiff kinetics, represented with mechanisms for hydrogen/carbon-monoxide (13 species and 54 irreversible reactions) and methane (53 species and 634 irreversible reactions) oxidation, were computed using the stabilized explicit second-order Runge-Kutta-Chebyshev (RKC) algorithm. The GPU-based RKC implementation demonstrated an increase in performance of nearly 59 and 10 times, for problem sizes consisting of 262,144 ODEs and larger, than the single- and six-core CPU-based RKC algorithms using the hydrogen/carbon-monoxide mechanism. With the methane mechanism, RKC-GPU performed more than 65 and 11 times faster, for problem sizes consisting of 131,072 ODEs and larger, than the single- and six-core RKC-CPU versions, and up to 57 times faster than the six-core CPU-based implicit VODE algorithm on 65,536 ODEs. In the presence of more severe stiffness, such as ethylene oxidation (111 species and 1566 irreversible reactions), RKC-GPU performed more than 17 times faster than RKC-CPU on six cores for 32,768 ODEs and larger, and at best 4.5 times faster than VODE on six CPU cores for 65,536 ODEs. With a larger time step size, RKC-GPU performed at best 2.5 times slower than six-core VODE for 8192 ODEs and larger. Therefore, the need for developing new strategies for integrating stiff chemistry on GPUs was discussed.

  14. Unsteady Dynamics of free falling of multi flexible fibers in moderate Reynolds number flows

    NASA Astrophysics Data System (ADS)

    Qi, Dewei

    2007-11-01

    The direct simulations of sedimentation of single and multi flexible fibers are conducted in moderate Reynolds number flows by using a newly developed method. In the method, for fluid domain, the lattice Boltzmann equations are used to solve the Navier Stokes equations. For solid domain, a fiber is discretized as a chain of rigid segments. The segments are connected through ball and socket joints and can be bent and twisted. Constraint forces are introduced at each joint. Translation and rotation matrix of fiber are linearized with respect to the constraint forces up to a second order of time step. Thus, motion of the fiber under the constraint and hydrodynamic forces could be solved by using a modified leap-frog algorithm. Effects of many body interaction on fiber fluttering are studied. It is found that in the same conditions initial fluttering may be damped by fluid viscosity for a single flexible fiber while irregular and persistent fluttering, rocking and oscillation may occur for a multi- fiber system. It is evident that clusters, such as doublets and triplets, are spontaneously formed and have a profound impact on unsteady dynamics of fibers. Two mechanisms contribute to an increase in unsteadiness. First the clusters have larger local settling velocity than a single fiber. Second, closely packed fibers become more ``fat'' or ``thick'' body and have a lower effective aspect ratio. The flows behind the 'fat' clusters tend to be more unsteady and induce vortex shedding that causes fibers persistently fluttering, rocking or oscillating. It is found that a fiber chain with a long vertical dimension is not stable. They will break down and become more flat structure. This property is directly related to that the fiber is preferentially oriented in horizontal direction due to inertia. In addition, the effects of flexibility on unsteady dynamics of sedimentation of flexible fiber are studied in a given range of Re. We find that when stiffness is very large, the

  15. Hyperbolic contraction measuring systems for extensional flow

    NASA Astrophysics Data System (ADS)

    Nyström, M.; Tamaddon Jahromi, H. R.; Stading, M.; Webster, M. F.

    2017-02-01

    In this paper an experimental method for extensional measurements on medium viscosity fluids in contraction flow is evaluated through numerical simulations and experimental measurements. This measuring technique measures the pressure drop over a hyperbolic contraction, caused by fluid extension and fluid shear, where the extensional component is assumed to dominate. The present evaluative work advances our previous studies on this experimental method by introducing several contraction ratios and addressing different constitutive models of varying shear and extensional response. The constitutive models included are those of the constant viscosity Oldroyd-B and FENE-CR models, and the shear-thinning LPTT model. Examining the results, the impact of shear and first normal stress difference on the measured pressure drop are studied through numerical pressure drop predictions. In addition, stream function patterns are investigated to detect vortex development and influence of contraction ratio. The numerical predictions are further related to experimental measurements for the flow through a 15:1 contraction ratio with three different test fluids. The measured pressure drops are observed to exhibit the same trends as predicted in the numerical simulations, offering close correlation and tight predictive windows for experimental data capture. This result has demonstrated that the hyperbolic contraction flow is well able to detect such elastic fluid properties and that this is matched by numerical predictions in evaluation of their flow response. The hyperbolical contraction flow technique is commended for its distinct benefits: it is straightforward and simple to perform, the Hencky strain can be set by changing contraction ratio, non-homogeneous fluids can be tested, and one can directly determine the degree of elastic fluid behaviour. Based on matching of viscometric extensional viscosity response for FENE-CR and LPTT models, a decline is predicted in pressure drop for

  16. Assessing stability in mild and moderate Parkinson's disease: Can clinical measures provide insight?

    PubMed

    Hubble, Ryan P; Silburn, Peter A; Naughton, Geraldine A; Cole, Michael H

    2016-09-01

    This cross-sectional study aimed to investigate the relationship between accelerometer-derived measures of movement rhythmicity and clinical measures of mobility, balance confidence and gait difficulty in people with Parkinson's disease (PD). Twenty-nine independently-living PD patients (Hoehn & Yahr Stages 1-3) with no history of significant injury or orthopaedic/deep brain stimulation surgery were recruited from a database of patients who had expressed an interest to participate in research. Participants completed clinical assessments of mobility, postural stability, balance confidence and symptom severity, while head and trunk rhythmicity was evaluated during gait using accelerometers. Following data collection, patients were stratified based on disease stage into either a Mild (Hoehn & Yahr Stage 1) or Moderate (Hoehn & Yahr Stages 2-3) PD group. The results highlighted that the Moderate PD group had poorer quality of life, reduced balance confidence and increased gait and falls difficulty. Furthermore, for these patients, gait disability and the number of previous falls were both negatively correlated with multiple components of head and trunk rhythmicity. For the Mild PD group, six-meter walk time was positively correlated with ML head rhythmicity and linear regression highlighted a significant predictive relationship between these outcomes. For the Mild and Moderate PD groups, balance confidence respectively predicted anterior-posterior trunk rhythmicity and vertical head rhythmicity. While these findings demonstrate that falls history and the Gait and Falls questionnaire provide moderate insight into head and trunk rhythmicity in Moderate PD patients, objective and clinically-feasible measures of postural instability would assist with the management of these symptoms.

  17. Helium-flow measurement using ultrasonic technique

    SciTech Connect

    Sondericker, J.H.

    1983-01-01

    While designing cryogenic instrumentation for the Colliding Beam Accelerator (CBA) helium-distribution system it became clear that accurate measurement of mass flow of helium which varied in temperature from room to sub-cooled conditions would be difficult. Conventional venturi flow meters full scale differential pressure signal would decrease by more than an order of magnitude during cooldown causing unacceptable error at operating temperature. At sub-cooled temperatures, helium would be pumped around cooling loops by an efficient, low head pressure circulating compressor. Additional pressure drop meant more pump work was necessary to compress the fluid resulting in a higher outlet temperature. The ideal mass flowmeter for this application was one which did not add pressure drop to the system, functioned over the entire temperature range, has high resolution and delivers accurate mass flow measurement data. Ultrasonic flow measurement techniques used successfully by the process industry, seemed to meet all the necessary requirements. An extensive search for a supplier of such a device found that none of the commercial stock flowmeters were adaptable to cryogenic service so the development of the instrument was undertaken by the CBA Cryogenic Control and Instrumentation Engineering Group at BNL.

  18. Solids flow rate measurement in dense slurries

    SciTech Connect

    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.

  19. Rectangular subsonic jet flow field measurements

    NASA Technical Reports Server (NTRS)

    Morrison, Gerald L.; Swan, David H.

    1990-01-01

    Flow field measurements of three subsonic rectangular cold air jets are presented. The three cases had aspect ratios of 1x2, 1x4 at a Mach number of 0.09 and an aspect ratio of 1x2 at a Mach number of 0.9. All measurements were made using a 3-D laser Doppler anemometer system. The data includes the mean velocity vector, all Reynolds stress tensor components, turbulent kinetic energy and velocity correlation coefficients. The data are presented in tabular and graphical form. No analysis of the measured data or comparison to other published data is made.

  20. 40 CFR 92.107 - Fuel flow measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... measurement. (a) Fuel flow measurement for locomotive and engine testing. The rate of fuel consumption by the... performed for at least 10 flow rates evenly distributed over the entire range of fuel flow rates used...

  1. Unified Model Deformation and Flow Transition Measurements

    NASA Technical Reports Server (NTRS)

    Burner, Alpheus W.; Liu, Tianshu; Garg, Sanjay; Bell, James H.; Morgan, Daniel G.

    1999-01-01

    The number of optical techniques that may potentially be used during a given wind tunnel test is continually growing. These include parameter sensitive paints that are sensitive to temperature or pressure, several different types of off-body and on-body flow visualization techniques, optical angle-of-attack (AoA), optical measurement of model deformation, optical techniques for determining density or velocity, and spectroscopic techniques for determining various flow field parameters. Often in the past the various optical techniques were developed independently of each other, with little or no consideration for other techniques that might also be used during a given test. Recently two optical techniques have been increasingly requested for production measurements in NASA wind tunnels. These are the video photogrammetric (or videogrammetric) technique for measuring model deformation known as the video model deformation (VMD) technique, and the parameter sensitive paints for making global pressure and temperature measurements. Considerations for, and initial attempts at, simultaneous measurements with the pressure sensitive paint (PSP) and the videogrammetric techniques have been implemented. Temperature sensitive paint (TSP) has been found to be useful for boundary-layer transition detection since turbulent boundary layers convect heat at higher rates than laminar boundary layers of comparable thickness. Transition is marked by a characteristic surface temperature change wherever there is a difference between model and flow temperatures. Recently, additional capabilities have been implemented in the target-tracking videogrammetric measurement system. These capabilities have permitted practical simultaneous measurements using parameter sensitive paint and video model deformation measurements that led to the first successful unified test with TSP for transition detection in a large production wind tunnel.

  2. Corrections on LIFPA velocity measurements in microchannel with moderate velocity fluctuations

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Yang, Fang; Khan, Jamil; Reifsnider, Ken; Wang, Guiren

    2015-02-01

    Laser-induced fluorescence photobleaching anemometer (LIFPA) has been developed in order to measure velocity fluctuations of the unsteady micro electrokinetic turbulent flows in microfluidics. The statistical errors of LIFPA measurement, because of 3-D flows and Taylor's hypothesis (compared with local Taylor's hypothesis Pinton and Labbé in J Phys II 4:1461-1468, 1994), are theoretically estimated and compared to hot-wire anemometer (HWA) measurement that is used for conventional turbulence measurement. The correction factor in the direction parallel to the laser beam is estimated, and the influence of directional correction factors of LIFPA is also investigated. It is found that in our investigation, the error due to Taylor's hypothesis is negligible. The influence of 3-D flows on the first derivative variance of velocity fluctuations in LIFPA is smaller than that in HWA measurement.

  3. 40 CFR 91.417 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Fuel flow measurement specifications... Procedures § 91.417 Fuel flow measurement specifications. (a) Fuel flow measurement is required only for raw testing but is allowed for dilute testing. (b) The fuel flow rate measurement instrument must have...

  4. 40 CFR 89.414 - Air flow measurement specifications.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Air flow measurement specifications... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method... incorporates devices that affect the air flow measurement (such as air bleeds) that result in......

  5. 40 CFR 90.417 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Fuel flow measurement specifications... Gaseous Exhaust Test Procedures § 90.417 Fuel flow measurement specifications. (a) Fuel flow measurement... measurement instrument must have a minimum accuracy of one percent of full-scale flow rate for...

  6. 40 CFR 91.416 - Intake air flow measurement specifications.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Intake air flow measurement... Procedures § 91.416 Intake air flow measurement specifications. (a) If used, the engine intake air flow measurement method used must have a range large enough to accurately measure the air flow over the...

  7. 40 CFR 89.414 - Air flow measurement specifications.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Air flow measurement specifications... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method... incorporates devices that affect the air flow measurement (such as air bleeds) that result in......

  8. 40 CFR 89.414 - Air flow measurement specifications.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Air flow measurement specifications. 89... Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method used... incorporates devices that affect the air flow measurement (such as air bleeds) that result in......

  9. 40 CFR 86.314-79 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Fuel flow measurement specifications....314-79 Fuel flow measurement specifications. (a) The fuel flow rate measurement instrument must have a minimum accuracy of ±1 percent of full-scale flow rate for each measurement range used. An exception...

  10. 40 CFR 91.417 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Fuel flow measurement specifications... Procedures § 91.417 Fuel flow measurement specifications. (a) Fuel flow measurement is required only for raw testing but is allowed for dilute testing. (b) The fuel flow rate measurement instrument must have...

  11. 40 CFR 86.314-79 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Fuel flow measurement specifications....314-79 Fuel flow measurement specifications. (a) The fuel flow rate measurement instrument must have a minimum accuracy of ±1 percent of full-scale flow rate for each measurement range used. An exception...

  12. 40 CFR 89.414 - Air flow measurement specifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Air flow measurement specifications... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method... incorporates devices that affect the air flow measurement (such as air bleeds) that result in......

  13. 40 CFR 89.414 - Air flow measurement specifications.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Air flow measurement specifications... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method... incorporates devices that affect the air flow measurement (such as air bleeds) that result in......

  14. 40 CFR 91.417 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Fuel flow measurement specifications... Procedures § 91.417 Fuel flow measurement specifications. (a) Fuel flow measurement is required only for raw testing but is allowed for dilute testing. (b) The fuel flow rate measurement instrument must have...

  15. 40 CFR 91.416 - Intake air flow measurement specifications.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Intake air flow measurement... Procedures § 91.416 Intake air flow measurement specifications. (a) If used, the engine intake air flow measurement method used must have a range large enough to accurately measure the air flow over the...

  16. 40 CFR 91.417 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Fuel flow measurement specifications... Procedures § 91.417 Fuel flow measurement specifications. (a) Fuel flow measurement is required only for raw testing but is allowed for dilute testing. (b) The fuel flow rate measurement instrument must have...

  17. 40 CFR 91.417 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Fuel flow measurement specifications... Procedures § 91.417 Fuel flow measurement specifications. (a) Fuel flow measurement is required only for raw testing but is allowed for dilute testing. (b) The fuel flow rate measurement instrument must have...

  18. 40 CFR 91.416 - Intake air flow measurement specifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Intake air flow measurement... Procedures § 91.416 Intake air flow measurement specifications. (a) If used, the engine intake air flow measurement method used must have a range large enough to accurately measure the air flow over the...

  19. 40 CFR 91.416 - Intake air flow measurement specifications.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Intake air flow measurement... Procedures § 91.416 Intake air flow measurement specifications. (a) If used, the engine intake air flow measurement method used must have a range large enough to accurately measure the air flow over the...

  20. EDITORIAL: Measurement techniques for multiphase flows Measurement techniques for multiphase flows

    NASA Astrophysics Data System (ADS)

    Okamoto, Koji; Murai, Yuichi

    2009-11-01

    Research on multiphase flows is very important for industrial applications, including power stations, vehicles, engines, food processing and so on. Multiphase flows originally have nonlinear features because of multiphase systems. The interaction between the phases plays a very interesting role in the flows. The nonlinear interaction causes the multiphase flows to be very complicated. Therefore techniques for measuring multiphase flows are very useful in helping to understand the nonlinear phenomena. The state-of-the-art measurement techniques were presented and discussed at the sixth International Symposium on Measurement Techniques for Multiphase Flows (ISMTMF2008) held in Okinawa, Japan, on 15-17 December 2008. This special feature of Measurement Science and Technology includes selected papers from ISMTMF2008. Okinawa has a long history as the Ryukyus Kingdom. China, Japan and many western Pacific countries have had cultural and economic exchanges through Okinawa for over 1000 years. Much technical and scientific information was exchanged at the symposium in Okinawa. The proceedings of ISMTMF2008 apart from these special featured papers were published in Journal of Physics: Conference Series vol. 147 (2009). We would like to express special thanks to all the contributors to the symposium and this special feature. This special feature will be a milestone in measurement techniques for multiphase flows.

  1. Aerodynamic Flow Field Measurements for Automotive Systems

    NASA Technical Reports Server (NTRS)

    Hepner, Timothy E.

    1999-01-01

    The design of a modern automotive air handling system is a complex task. The system is required to bring the interior of the vehicle to a comfortable level in as short a time as possible. A goal of the automotive industry is to predict the interior climate of an automobile using advanced computational fluid dynamic (CFD) methods. The development of these advanced prediction tools will enable better selection of engine and accessory components. The goal of this investigation was to predict methods used by the automotive industry. To accomplish this task three separate experiments were performed. The first was a laboratory setup where laser velocimeter (LV) flow field measurements were made in the heating and air conditioning unit of a Ford Windstar. The second involved flow field measurements in the engine compartment of a Ford Explorer, with the engine running idle. The third mapped the flow field exiting the center dashboard panel vent inside the Explorer, while the circulating fan operated at 14 volts. All three experiments utilized full-coincidence three-component LV systems. This enabled the mean and fluctuating velocities to be measured along with the Reynolds stress terms.

  2. Measurement of Liver Blood Flow: A Review

    PubMed Central

    Stansby, G. P.; Hobbs, K. E. F.; Hawkes, D. J.; Colchester, A. C. F.

    1991-01-01

    The study of hepatic haemodynamics is of importance in understanding both hepatic physiology and disease processes as well as assessing the effects of portosystemic shunting and liver transplantation. The liver has the most complicated circulation of any organ and many physiological and pathological processes can affect it1,2. This review surveys the methods available for assessing liver blood flow, examines the different parameters being measured and outlines problems of applicability and interpretation for each technique. The classification of these techniques is to some extent arbitrary and several so called “different” methods may share certain common principles. The methods reviewed have been classified into two groups (Table 1): those primarily reflecting flow through discrete vessels or to the whole organ and those used to assess local microcirculatory blood flow. All techniques have their advantages and disadvantages and in some situations a combination may provide the most information. In addition, because of the many factors affecting liver blood flow and sinusoidal perfusion, readings in a single subject may vary depending on positioning, recent food intake, anxiety, anaesthesia and drug therapy. This must be borne in mind if different studies are to be meaningfully compared. PMID:1931785

  3. Pulmonary O2 uptake and leg blood flow kinetics during moderate exercise are slowed by hyperventilation-induced hypocapnic alkalosis

    PubMed Central

    Chin, Lisa M. K.; Heigenhauser, George J. F.; Paterson, Donald H.

    2010-01-01

    The effect of hyperventilation-induced hypocapnic alkalosis (Hypo) on the adjustment of pulmonary O2 uptake (V̇o2p) and leg femoral conduit artery (“bulk”) blood flow (LBF) during moderate-intensity exercise (Mod) was examined in eight young male adults. Subjects completed four to six repetitions of alternate-leg knee-extension exercise during normal breathing [Con; end-tidal partial pressure of CO2 (PetCO2) ∼40 mmHg] and sustained hyperventilation (Hypo; PetCO2 ∼20 mmHg). Increases in work rate were made instantaneously from baseline (3 W) to Mod (80% estimated lactate threshold). V̇o2p was measured breath by breath by mass spectrometry and volume turbine, and LBF (calculated from mean femoral artery blood velocity and femoral artery diameter) was measured simultaneously by Doppler ultrasound. Concentration changes of deoxy (Δ[HHb])-, oxy (Δ[O2Hb])-, and total hemoglobin-myoglobin (Δ[HbTot]) of the vastus lateralis muscle were measured continuously by near-infrared spectroscopy (NIRS). The kinetics of V̇o2p, LBF, and Δ[HHb] were modeled using a monoexponential equation by nonlinear regression. The time constants for the phase 2 V̇o2p (Hypo, 49 ± 26 s; Con, 28 ± 8 s) and LBF (Hypo, 46 ± 16 s; Con, 23 ± 6 s) were greater (P < 0.05) in Hypo compared with Con. However, the mean response time for the overall Δ[HHb] response was not different between conditions (Hypo, 23 ± 5 s; Con, 24 ± 3 s), whereas the Δ[HHb] amplitude was greater (P < 0.05) in Hypo (8.05 ± 7.47 a.u.) compared with Con (6.69 ± 6.31 a.u.). Combined, these results suggest that hyperventilation-induced hypocapnic alkalosis is associated with slower convective (i.e., slowed femoral artery and microvascular blood flow) and diffusive (i.e., greater fractional O2 extraction for a given ΔV̇o2p) O2 delivery, which may contribute to the hyperventilation-induced slowing of V̇o2p (and muscle O2 utilization) kinetics. PMID:20339012

  4. Mesoscale meteorological measurements characterizing complex flows

    SciTech Connect

    Hubbe, J.M.; Allwine, K.J.

    1993-09-01

    Meteorological measurements are an integral and essential component of any emergency response system for addressing accidental releases from nuclear facilities. An important element of the US Department of Energy`s (DOE`s) Atmospheric Studies in Complex Terrain (ASCOT) program is the refinement and use of state-of-the-art meteorological instrumentation. ASCOT is currently making use of ground-based remote wind sensing instruments such as doppler acoustic sounders (sodars). These instruments are capable of continuously and reliably measuring winds up to several hundred meters above the ground, unattended. Two sodars are currently measuring the winds, as part of ASCOT`s Front Range Study, in the vicinity of DOE`s Rocky Flats Plant (RFP) near Boulder, Colorado. A brief description of ASCOT`s ongoing Front Range Study is given followed by a case study analysis that demonstrates the utility of the meteorological measurement equipment and the complexity of flow phenomena that are experienced near RFP. These complex flow phenomena can significantly influence the transport of the released material and consequently need to be identified for accurate assessments of the consequences of a release.

  5. Holocinematographic velocimetry - Resolution limitation for flow measurement

    NASA Astrophysics Data System (ADS)

    Liburdy, James A.

    1987-10-01

    The goal of developing a holocinematographic velocimeter (HCV) is to provide a technique to study the evolution of instantaneous three-dimensional velocity profiles in turbulent flow fields. The method tracks individual seed particles that have been introduced into the flow. An imaging system using far-field holography is used to provide a full field of view tracking. Velocity information is determined from measured particle displacements of sequential hologram reconstruction. This study examines the resolution limits of far-field holography as applied to the HCV. The results aid in the determination of required seeding concentrations, establish the ability to resolve particle centers, and illustrate the use of a dual TV camera system to aid resolution. A straightforward enhancement technique provides a means to eliminate noise and reduce out of image plane ambiguity.

  6. Flow Measurement by Means of Light Interference

    NASA Technical Reports Server (NTRS)

    Zobel, Th.

    1949-01-01

    There has been under development for the high-speed wind tunnel of the LFA an optical measuring arrangement for the qualitative and quantitative investigation of flow. By the use of interference measurements, the determination of density at the surface of the bodies being tested in the air stream and in the vicinity of these bodies can be undertaken. The results obtained so far in the simple preliminary investigations show that it is possible, even at a low Reynolds number, to obtain the density field in the neighborhood of a test body by optical means. Simple analytical expressions give the relation between density, pressure, velocity, and temperature. In addition to this, the interference measurement furnishes valuable data on the state of the boundary layer, that is, the sort of boundary layer (whether laminar or turbulent), as well as the temperature and velocity distribution.

  7. Measurement of Flow-Mediated Vasodilatation.

    PubMed

    Tomiyama, Hirofumi; Saisu, Tomoko; Yamashina, Akira

    2017-04-06

    The FMDJ study, a multicenter prospective observational study conducted in Japan, demonstrated the acceptable reliability of measurement of flow-mediated vasodilatation (FMD) using a semi-automatic device in individual institutions. However, in about 10% of Japanese subjects, adequate scans to determine the brachial arterial diameter failed to be obtained. The prevalence of inadequate scans was higher in women than in men, while obesity had no influence on the inadequate scan rate. The FMDJ study also proposed that attending periodic refresher courses on the measurement of FMD is needed for maintaining competency. Finally, the FMDJ study proposed reference values for FMD. Thus, FMD measurement may be categorized as a clinically applicable tool on the basis of class IIb (exploratory cohort study with good reference standards) evidence.

  8. Rectangular subsonic jet flow field measurements

    NASA Technical Reports Server (NTRS)

    Morrison, Gerald L.; Swan, David H.

    1989-01-01

    Flow field measurements are presented of 3 subsonic rectangular cold air jets. The 3 cases presented had aspect ratios of 1 x 2, 1 x 4 at a Mach number of 0.09 and an aspect ratio of 1 x 2 at a Mach number of 0.9. All measurements were made using a 3-D laser Doppler anemoneter system. The presented data includes the mean velocity vector, all Reynolds stress tensor components, turbulent kinetic energy and velocity correlation coefficients. The data is presented in tabular and graphical form. No analysis of the measured data or comparison to other published data is made. All tabular data are available in ASCII format on MS-DOS compatible disks.

  9. Turbulence measurements in high-speed flows by resonant fluoresence

    NASA Technical Reports Server (NTRS)

    Miles, R. B.

    1982-01-01

    Both mean flow and turbulence measurements were investigated using the resonant Doppler velocimeter in a Mach 3.2 nitrogen flow. Data are presented showing velocity, temperature and pressure measured point by point across the flow field. This data is compared with conventional pitot and temperature surveys. Turbulence was induced by a small metal tab in the flow and observed by both hot wire and RDV techniques. Photographs of the flow field demonstrate the utility of the RDV for quantitative flow field visualization.

  10. 40 CFR 90.416 - Intake air flow measurement specifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Intake air flow measurement... Gaseous Exhaust Test Procedures § 90.416 Intake air flow measurement specifications. (a) If used, the engine intake air flow measurement method used must have a range large enough to accurately measure...

  11. 40 CFR 90.416 - Intake air flow measurement specifications.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Intake air flow measurement... Gaseous Exhaust Test Procedures § 90.416 Intake air flow measurement specifications. (a) If used, the engine intake air flow measurement method used must have a range large enough to accurately measure...

  12. 40 CFR 90.416 - Intake air flow measurement specifications.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Intake air flow measurement... Gaseous Exhaust Test Procedures § 90.416 Intake air flow measurement specifications. (a) If used, the engine intake air flow measurement method used must have a range large enough to accurately measure...

  13. 40 CFR 90.416 - Intake air flow measurement specifications.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Intake air flow measurement... Gaseous Exhaust Test Procedures § 90.416 Intake air flow measurement specifications. (a) If used, the engine intake air flow measurement method used must have a range large enough to accurately measure...

  14. Real-time method for NO(2) flow measurements.

    PubMed

    Darrah, R C; Andrews, M L; Garscadden, A; Bletzinger, P

    1978-07-01

    Measurements of NO(2) flows are made without requiring prior experimental calibration of the flow meter. A tapered, variable area flow meter with a diameter ratio scale is used to make the real-time NO(2) flow measurements. The necessary parameters and calculations used to determine the viscosity and density of the flowing N(2)O(4)2NO(2) gas are presented. The limits of error associated with these parameters and errors associated with controlled flow measurement conditions are considered. Disregarding the scale reading error, which depends on the flow meter utilized, the limits of error are found to yield a measurement error less than 7%.

  15. Meteorological insights from planetary heat flow measurements

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.

    2015-04-01

    Planetary heat flow measurements are made with a series of high-precision temperature sensors deployed in a column of regolith to determine the geothermal gradient. Such sensors may, however, be susceptible to other influences, especially on worlds with atmospheres. First, pressure fluctuations at the surface may pump air in and out of pore space leading to observable, and otherwise unexpected, temperature fluctuations at depth. Such pumping is important in subsurface radon and methane transport on Earth: evidence of such pumping may inform understanding of methane or water vapor transport on Mars. Second, the subsurface profile contains a muted record of surface temperature history, and such measurements on other worlds may help constrain the extent to which Earth's Little Ice Age was directly solar-forced, versus volcanic-driven and/or amplified by climate feedbacks.

  16. Flow cytometer measurement of binding assays

    DOEpatents

    Saunders, George C.

    1987-01-01

    A method of measuring the result of a binding assay that does not require separation of fluorescent smaller particles is disclosed. In a competitive binding assay the smaller fluorescent particles coated with antigen compete with antigen in the sample being analyzed for available binding sites on larger particles. In a sandwich assay, the smaller, fluorescent spheres coated with antibody attach themselves to molecules containing antigen that are attached to larger spheres coated with the same antibody. The separation of unattached, fluorescent smaller particles is made unnecessary by only counting the fluorescent events triggered by the laser of a flow cytometer when the event is caused by a particle with a light scatter measurement within a certain range corresponding to the presence of larger particles.

  17. Method and Apparatus for Measuring Fluid Flow

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Nguyen, Thanh X. (Inventor); Carl, James R. (Inventor)

    1997-01-01

    Method and apparatus for making measurements on fluids related to their complex permeability are disclosed. A microwave probe is provided for exposure to the fluids. The probe can be non-intrusive or can also be positioned at the location where measurements are to be made. The impedance of the probe is determined. in part. by the complex dielectric constant of the fluids at the probe. A radio frequency signal is transmitted to the probe and the reflected signal is phase and amplitude detected at a rapid rate for the purpose of identifying the fluids. Multiple probes may be selectively positioned to monitor the behavior of the fluids including their flow rate. Fluids may be identified as between two or more different fluids as well as multiple phases of the same fluid based on differences between their complex permittivities.

  18. Transcutaneous measurement of volume blood flow

    NASA Technical Reports Server (NTRS)

    Daigle, R. E.; Mcleod, F. D.; Miller, C. W.; Histand, M. B.; Wells, M. K.

    1974-01-01

    Blood flow velocity measurements, using Doppler velocimeter, are described. The ability to measure blood velocity using ultrasound is derived from the Doppler effect; the change in frequency which occurs when sound is reflected or transmitted from a moving target. When ultrasound of the appropriate frequency is transmitted through a moving blood stream, the blood cells act as point scatterers of ultrasonic energy. If this scattered ultrasonic energy is detected, it is found to be shifted in frequency according to the velocity of the blood cells, nu, the frequency of the incident sound, f sub o, the speed of sound in the medium, c, and the angle between the sound beam and the velocity vector, o. The relation describing this effect is known as the Doppler equation. Delta f = 2 f sub o x nu x cos alpha/c. The theoretical and experimental methods are evaluated.

  19. Improved flow cytometer measurement of binding assays

    DOEpatents

    Saunders, G.C.

    1984-05-30

    The invention relates to a method of measuring binding assays carried out with different size particles wherein the binding assay sample is run through a flow cytometer without separating the sample from the marking agent. The amount of a binding reactant present in a sample is determined by providing particles with a coating of binder and also a known quantity of smaller particles with a coating of binder reactant. The binding reactant is the same as the binding reactant present in the sample. The smaller particles also contain a fluorescent chemical. The particles are combined with the sample and the binding reaction is allowed to occur for a set length of time followed by combining the smaller particles with the mixture of the particles and the sample produced and allowing the binding reactions to proceed to equilibrium. The fluorescence and light scatter of the combined mixture is then measured as the combined mixture passes through a flow cytometer equipped with a laser to bring about fluorescence, and the number and strength of fluorescent events are compared. A similar method is also provided for determining the amount of antigen present in the sample by providing spheres with an antibody coating and some smaller spheres with an antigen coating. (LEW)

  20. Flowmeter measures flow rates of high temperature fluids

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1966-01-01

    Flowmeter in which flow rate is determined by measuring the position and thus the displacement of an internal float acted upon by the flowing fluid determines the flow rates of various liquid metals at elevated temperatures. Viscous forces cause the float to move from its mounted position, affording several means for measuring this motion and the flow rate.

  1. Three dimensional flow measurements in a turbine scroll

    NASA Technical Reports Server (NTRS)

    Tabakoff, W.; Vittal, B. V. R.; Wood, B.

    1982-01-01

    A study was conducted to determine experimentally the flow behavior in combined scroll nozzle assembly of a radial inflow turbine. Hot film anemometry technique was used to measure the three dimensional flow velocity in the scroll. The through flow and secondary flow velocity components are measured at various points in three scroll sections.

  2. Method and Apparatus for Measuring Fluid Flow

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Nguyen, Than X. (Inventor); Carl, James R. (Inventor)

    1995-01-01

    The invention is a method and apparatus for monitoring the presence, concentration, and the movement of fluids. It is based on utilizing electromagnetic measurements of the complex permittivity of the fluids for detecting and monitoring the fluid. More particularly the apparatus uses one or more microwave probes which are placed at the locations where the measurements are to be made. A radio frequency signal is transmitted to the probe and the reflected signal is phase and amplitude detected at a rapid rate for the purpose of identifying the fluids, based on their dielectric constant at the probe. The apparatus can be used for multiple purposes including measures of flow rates, turbulence, dispersion, fluid identification, and changes in flow conditions of multiple fluids or multiple states of a single fluid in a flowline or a holding container. The apparatus includes a probe consisting of two electrical conductors separated by an insulator. A radio frequency signal is communicated to the probe and is reflected back from the portion of the probe exposed to the fluid. The radio frequency signal also provides a reference signal. An oscillator generates a second signal which combined with each of the reference signal and the reflected signal to produce signals of lower frequencies to facilitate filtering and amplifying those signals. The two signals are then mixed in a detector to produce an output signal that is representative of the phase and amplitude change caused by the reflection of the signal at the probe exposed to the fluid. The detector may be a dual phase detector that provides two such output signals that are in phase quadrature. A phase shifter may be provided for selectively changing the phase of the reference signal to improve the sensitivity of at least one of the output signals for more accurate readings and/or for calibration purposes. The two outputs that are in quadrature with respect to each other may be simultaneously monitored to account for

  3. [Improve, but measure in moderation; quality management in specialty residency training].

    PubMed

    Ter Braak, E W M T

    2017-01-01

    Intuitively, we believe we gain knowledge through taking measurements, and our appetite for quality measurement in general has grown spectacularly. However, this approach has to be qualified. Many aspects of quality are difficult to measure, yet are very important, and choosing what to measure may be heavily influenced by the availability bias of instruments. Moreover, a lot can be known without actually measuring. Quantitative results tend to offer false reassurance simply by their abundance, and results presented by means of Likert scales may obscure the crucial critique of a minority of respondents. Narrative comments in surveys are often much more meaningful as they can foster an open dialogue between residents and their clinical teachers, preferably led by a neutral chairperson. Contrary to what is often claimed, it is even possible to engage in improvement without prior measurement. I propose measuring only in moderation and instead devoting time and money to patient care and educating residents, and on the design and execution of improvement plans.

  4. On the Scaling of Small, Heat Simulated Jet Noise Measurements to Moderate Size Exhaust Jets

    NASA Technical Reports Server (NTRS)

    McLaughlin, Dennis K.; Bridges, James; Kuo, Ching-Wen

    2010-01-01

    Modern military aircraft jet engines are designed with variable geometry nozzles to provide optimum thrust in different operating conditions, depending on the flight envelope. However, the acoustic measurements for such nozzles are scarce, due to the cost involved in making full scale measurements and the lack of details about the exact geometry of these nozzles. Thus the present effort at The Pennsylvania State University and the NASA Glenn Research Center- in partnership with GE Aviation is aiming to study and characterize the acoustic field produced by supersonic jets issuing from converging-diverging military style nozzles. An equally important objective is to validate methodology for using data obtained from small and moderate scale experiments to reliably predict the most important components of full scale engine noise. The experimental results presented show reasonable agreement between small scale and moderate scale jet acoustic data, as well as between heated jets and heat-simulated ones. Unresolved issues however are identified that are currently receiving our attention, in particular the effect of the small bypass ratio airflow. Future activities will identify and test promising noise reduction techniques in an effort to predict how well such concepts will work with full scale engines in flight conditions.

  5. Effects of mild (33 degrees C) and moderate (29 degrees C) hypothermia on cerebral blood flow and metabolism, lactate, and extracellular glutamate in experimental head injury.

    PubMed

    Mori, K; Maeda, M; Miyazaki, M; Iwase, H

    1998-12-01

    The effects of mild (33 degrees C) and moderate (29 degrees C) hypothermia were investigated to determine which temperature was more effective against compression-induced cerebral ischemia. Eighteen cats were anesthetized. The animals were divided into three groups according to deep-brain temperature (control, 37 degrees C; mild hypothermia, 33 degrees C; and moderate hypothermia, 29 degrees C). Intracranial pressure (ICP) and cerebral blood flow (CBF) were monitored, the latter by hydrogen clearance. Arteriovenous oxygen difference (AVDO2) and cerebral venous oxygen saturation (ScvO2) were measured in blood samples from the superior sagittal sinus. The cerebral metabolic rate of oxygen (CMRO2) and the cerebral metabolic rate of lactate (CMR lactate) were calculated. Extracellular glutamate was measured by microdialysis. ICP was increased by inflation of an epidural balloon until CBF became zero, and this ischemia was maintained for 5 min, after which the balloon was quickly deflated. All parameters were recorded over 6 h. Evans blue was injected to examine vascular permeability changes. CBF was decreased by 56% by mild hypothermia and by 77% by moderate hypothermia. Mild hypothermia had a coupled metabolic suppression whereas moderate hypothermia significantly increased AVDO2 and decreased ScvO2, producing a low CBF/CMRO2 (relative ischemia). After balloon deflation, all three groups showed reactive hyperemia, which was significantly reduced by mild and moderate hypothermia. CBF then decreased to 50% of pre-inflation values and ScvO2 decreased (post-ischemic hypoperfusion). CBF/CMRO2, ScvO2, and AVDO2 did not differ significantly between the three groups. After balloon deflation, all three groups showed increased CMR lactate, which was significantly reduced by mild and moderate hypothermia. Extracellular glutamate increased in control animals (3.8 +/- 1.72 microM), an effect most effectively suppressed in the mild hypothermia group (1.0 +/- 0.46 microM). Damaged

  6. 40 CFR 90.417 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... measurement instrument must have a minimum accuracy of one percent of full-scale flow rate for each... ±five percent of full-scale flow rate for the measurement range used. The controlling parameters are...

  7. 40 CFR 90.417 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... measurement instrument must have a minimum accuracy of one percent of full-scale flow rate for each... ±five percent of full-scale flow rate for the measurement range used. The controlling parameters are...

  8. 40 CFR 90.417 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... measurement instrument must have a minimum accuracy of one percent of full-scale flow rate for each... ±five percent of full-scale flow rate for the measurement range used. The controlling parameters are...

  9. 40 CFR 90.417 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... measurement instrument must have a minimum accuracy of one percent of full-scale flow rate for each... ±five percent of full-scale flow rate for the measurement range used. The controlling parameters are...

  10. Method and apparatus for measuring flow velocity using matched filters

    SciTech Connect

    Raptis, A.C.

    1981-07-17

    An apparatus and method for measuring the flow velocities of individual phase flow components of a multiphase flow is disclosed. Signals arising from flow noise disturbance are extracted from the flow, at upstream and downstream locations. The signals are processed through pairs of matched filters which are matched to the flow disturbance frequency characteristics of the phase flow component to be measured. The processed signals are then cross-correlated to determine the transit delay time of the phase flow component between sensing positions.

  11. Method and apparatus for measuring flow velocity using matched filters

    DOEpatents

    Raptis, Apostolos C.

    1983-01-01

    An apparatus and method for measuring the flow velocities of individual phase flow components of a multiphase flow utilizes matched filters. Signals arising from flow noise disturbance are extracted from the flow, at upstream and downstream locations. The signals are processed through pairs of matched filters which are matched to the flow disturbance frequency characteristics of the phase flow component to be measured. The processed signals are then cross-correlated to determine the transit delay time of the phase flow component between sensing positions.

  12. Method and apparatus for measuring flow velocity using matched filters

    DOEpatents

    Raptis, A.C.

    1983-09-06

    An apparatus and method for measuring the flow velocities of individual phase flow components of a multiphase flow utilizes matched filters. Signals arising from flow noise disturbance are extracted from the flow, at upstream and downstream locations. The signals are processed through pairs of matched filters which are matched to the flow disturbance frequency characteristics of the phase flow component to be measured. The processed signals are then cross-correlated to determine the transit delay time of the phase flow component between sensing positions. 8 figs.

  13. Flow in a differentially rotated cylindrical drop at moderate Reynolds number

    NASA Astrophysics Data System (ADS)

    Harriott, G. M.; Brown, R. A.

    1984-07-01

    Galerkin finite-element approximations are combined with computer-implemented perturbation methods for tracking families of solutions to calculate the steady axisymmetric flows in a differentially rotated cylindrical drop as a function of Reynolds number Re, drop aspect ratio and the rotation ratio between the two end disks. The flows for Reynolds numbers below 100 are primarily viscous and reasonably described by an asymptotic analysis. When the disks are exactly counter-rotated, multiple steady flows are calculated that bifurcate to higher values of Re from the expected solution with two identical secondary cells stacked symmetrically about the axial midplane. The new flows have two cells of different size and are stable beyond the critical value Re sub c. The slope of the locus of Re sub c for drops with aspect ratio up to 3 disagrees with the result for two disks of infinite radius computed assuming the similarity form of the velocity field. Changing the rotation ratio for exact counter-rotation ruptures the junction of the multiple flow fields into two separated flow families.

  14. Measuring vortical flows in the solar interior

    NASA Astrophysics Data System (ADS)

    Langfellner, Jan

    2015-09-01

    This thesis focuses on observations of the effects of rotation on solar convection at the length scales of supergranulation and larger (>30 Mm). Rotation drives vortical flows through the Coriolis force and causes anisotropic velocity correlations that are believed to influence the large-scale solar dynamics. We obtain horizontal flows using photospheric Doppler velocity and continuum intensity images from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) spacecraft via the techniques of time-distance helioseismology (TD) and local correlation tracking (LCT) of granules. In time-distance helioseismology, the local vertical vorticity can be measured by taking the difference between wave travel times measured in the anti-clockwise and clockwise directions along a closed contour. The agreement between the TD and LCT methods is excellent up to ±60° latitude, provided that a center-to-limb correction is applied. Averaging over longitude, one finds that there is a small but significant correlation between the horizontal divergence and the vertical vorticity component of supergranular flows away from the solar equator. By comparison to a noise model, we find that the TD technique can be used to probe the vertical vorticity of flows on spatial scales larger than about 15 Mm, thus including supergranules and also giant cells. We also find that the vertical vorticity signal is much easier to measure using SDO/HMI observations than previous observations. The impact of the Sun's rotation on supergranulation is studied in detail by making spatial maps of the vertical vorticity of the flows associated with the average supergranule. The average supergranule is constructed by co-aligning thousands of individual supergranules in a given latitude band. For the first time, we are able to spatially resolve vorticity associated with inflows and outflow regions. In the northern hemisphere, outflows are on average associated with a clockwise

  15. Asymptotic theory of two-phase gas-solid flow through a vertical tube at moderate pressure gradient

    NASA Astrophysics Data System (ADS)

    Sergeev, Y. A.; Zhurov, A. I.

    1997-02-01

    Based on the equations, constitutive relations and boundary conditions of the kinetic theory of colliding particles in a gas-solid suspension, the approximate theory of the steady, developed vertical flow of a gas-particulate mixture is developed for the case of moderate gas pressure gradient in a vertical tube. The basic equations and boundary conditions show a singular behaviour of the solution of the problem at the wall. The method of matched asymptotic expansions is applied to develop a boundary layer-type theory for the flow parameters of the particulate phase. The basic equations in the bulk flow are reduced to a system of two ordinary integrodifferential equations for the particle-phase concentration and mean kinetic energy of particle velocity fluctuations (particle-phase pseudotemperature). The distributions of the particle concentration and velocity are found in both the bulk and the boundary layer. The solutions shows the bifurcation of flow parameters, and an explicit criterion is derived to identify a range of the given macroscopic parameters corresponding to upward or downward particulate flow. The integrated parameters (total fluxes of the gas and particle phase) are calculated.

  16. Ultrasonic fluid flow measurement method and apparatus

    DOEpatents

    Kronberg, James W.

    1993-01-01

    An apparatus for measuring the flow of a fluid in a pipe using ultrasonic waves. The apparatus comprises an ultrasonic generator, a lens for focusing the sound energy produced by the generator, and means for directing the focused energy into the side of the pipe through an opening and in a direction close to parallel to the long axis of the pipe. A cone carries the sound energy to the lens from the generator. Depending on the choice of materials, there may be a quarter-wave, acoustic impedance matching section between the generator and the cone to reduce the reflections of energy at the cone boundary. The lens material has an acoustic impedance similar to that of the cone material but a different sonic velocity so that the lens can converge the sound waves in the fluid. A transition section between the lens and the fluid helps to couple the energy to the fluid and assures it is directed as close to parallel to the fluid flow direction as possible.

  17. Ultrasonic fluid flow measurement method and apparatus

    DOEpatents

    Kronberg, J.W.

    1993-10-12

    An apparatus for measuring the flow of a fluid in a pipe using ultrasonic waves. The apparatus comprises an ultrasonic generator, a lens for focusing the sound energy produced by the generator, and means for directing the focused energy into the side of the pipe through an opening and in a direction close to parallel to the long axis of the pipe. A cone carries the sound energy to the lens from the generator. Depending on the choice of materials, there may be a quarter-wave, acoustic impedance matching section between the generator and the cone to reduce the reflections of energy at the cone boundary. The lens material has an acoustic impedance similar to that of the cone material but a different sonic velocity so that the lens can converge the sound waves in the fluid. A transition section between the lens and the fluid helps to couple the energy to the fluid and assures it is directed as close to parallel to the fluid flow direction as possible. 3 figures.

  18. 40 CFR 92.107 - Fuel flow measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Fuel flow measurement. 92.107 Section...) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures § 92.107 Fuel flow measurement. (a) Fuel flow measurement for locomotive and engine testing. The rate of fuel consumption by...

  19. 40 CFR 92.107 - Fuel flow measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Fuel flow measurement. 92.107 Section...) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures § 92.107 Fuel flow measurement. (a) Fuel flow measurement for locomotive and engine testing. The rate of fuel consumption by...

  20. 40 CFR 92.107 - Fuel flow measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Fuel flow measurement. 92.107 Section...) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures § 92.107 Fuel flow measurement. (a) Fuel flow measurement for locomotive and engine testing. The rate of fuel consumption by...

  1. 40 CFR 92.107 - Fuel flow measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Fuel flow measurement. 92.107 Section...) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures § 92.107 Fuel flow measurement. (a) Fuel flow measurement for locomotive and engine testing. The rate of fuel consumption by...

  2. Moderately converging ion and electron flows in two-dimensional diodes

    SciTech Connect

    Cavenago, M.

    2012-11-15

    Flow of particles in diodes is solved selfconsistently assuming an approximated system of flow lines, that can be easily represented by an analytic transformation in a complex plane, with assumed uniformity in the third spatial direction. Beam current compression is tunable by an angle parameter {alpha}{sub 0}; transformed coordinate lines are circular arcs, exactly matching to the curved cathode usually considered by rectilinear converging flows. The curvature of flow lines allows to partly balance the transverse effect of space charge. A self-contained discussion of the whole theory is reported, ranging from analytical solution for selfconsistent potential to electrode drawing to precise numerical simulation, which serves as a verification and as an illustration of typical electrode shapes. Motion and Poisson equation are written in a curved flow line system and their approximate consistency is shown to imply an ordinary differential equation for the beam edge potential. Transformations of this equation and their series solutions are given and discussed, showing that beam edge potential has a maximum, so supporting both diode (with {alpha}{sub 0}{approx_equal}{pi}/3) and triode design. Numerical simulations confirm the consistency of these solution. Geometrical details of diode design are discussed: the condition of a zero divergence beam, with the necessary anode lens effect included, is written and solved, as a function of beam compression; accurate relations for diode parameters and perveance are given. Weakly relativistic effects including self-magnetic field are finally discussed as a refinement.

  3. Moderately converging ion and electron flows in two-dimensional diodes

    NASA Astrophysics Data System (ADS)

    Cavenago, M.

    2012-11-01

    Flow of particles in diodes is solved selfconsistently assuming an approximated system of flow lines, that can be easily represented by an analytic transformation in a complex plane, with assumed uniformity in the third spatial direction. Beam current compression is tunable by an angle parameter α0; transformed coordinate lines are circular arcs, exactly matching to the curved cathode usually considered by rectilinear converging flows. The curvature of flow lines allows to partly balance the transverse effect of space charge. A self-contained discussion of the whole theory is reported, ranging from analytical solution for selfconsistent potential to electrode drawing to precise numerical simulation, which serves as a verification and as an illustration of typical electrode shapes. Motion and Poisson equation are written in a curved flow line system and their approximate consistency is shown to imply an ordinary differential equation for the beam edge potential. Transformations of this equation and their series solutions are given and discussed, showing that beam edge potential has a maximum, so supporting both diode (with α0 ≅ π/3) and triode design. Numerical simulations confirm the consistency of these solution. Geometrical details of diode design are discussed: the condition of a zero divergence beam, with the necessary anode lens effect included, is written and solved, as a function of beam compression; accurate relations for diode parameters and perveance are given. Weakly relativistic effects including self-magnetic field are finally discussed as a refinement.

  4. Numerical Dissipation and Subgrid Scale Modeling for Separated Flows at Moderate Reynolds Numbers

    NASA Astrophysics Data System (ADS)

    Cadieux, Francois; Domaradzki, Julian Andrzej

    2014-11-01

    Flows in rotating machinery, for unmanned and micro aerial vehicles, wind turbines, and propellers consist of different flow regimes. First, a laminar boundary layer is followed by a laminar separation bubble with a shear layer on top of it that experiences transition to turbulence. The separated turbulent flow then reattaches and evolves downstream from a nonequilibrium turbulent boundary layer to an equilibrium one. In previous work, the capability of LES to reduce the resolution requirements down to 1 % of DNS resolution for such flows was demonstrated (Cadieux et al., JFE 136-6). However, under-resolved DNS agreed better with the benchmark DNS than simulations with explicit SGS modeling because numerical dissipation and filtering alone acted as a surrogate SGS dissipation. In the present work numerical viscosity is quantified using a new method proposed recently by Schranner et al. and its effects are analyzed and compared to turbulent eddy viscosities of explicit SGS models. The effect of different SGS models on a simulation of the same flow using a non-dissipative code is also explored. Supported by NSF.

  5. Bodies in flowing plasmas - Spacecraft measurements

    NASA Technical Reports Server (NTRS)

    Samir, U.

    1981-01-01

    Results are reviewed from in-situ measurements relevant to the interaction of bodies in flowing plasmas. A brief discussion is given of the interaction in the general context of space plasma physics, including possible applications to solar-system plasmas. Attention is given to the mode of experimentation in the Shuttle/Spacelab era. It is noted that the majority of in-situ investigations during the past decade were limited to the very near surface of ionospheric satellites. It is expected that experiments to be carried out on board the Spacelab/Orbiter will make possible well-planned controlled experiments in the area of body-plasma interactions in its widest sense.

  6. Novel laser Doppler flowmeter for pulpal blood flow measurements

    NASA Astrophysics Data System (ADS)

    Zang, De Yu; Millerd, James E.; Wilder-Smith, Petra B. B.; Arrastia-Jitosho, Anna-Marie A.

    1996-04-01

    We have proposed and experimentally demonstrated a new configuration of laser Doppler flowmetry for dental pulpal blood flow measurements. To date, the vitality of a tooth can be determined only by subjective thermal or electric tests, which are of questionable reliability and may induced pain in patient. Non-invasive techniques for determining pulpal vascular reactions to injury, treatment, and medication are in great demand. The laser Doppler flowmetry technique is non-invasive; however, clinical studies have shown that when used to measure pulpal blood flow the conventional back-scattering Doppler method suffers from low signal-to-noise ratio (SNR) and unreliable flux readings rendering it impossible to calibrate. A simplified theoretical model indicates that by using a forward scattered geometry the detected signal has a much higher SNR and can be calibrated. The forward scattered signal is readily detectable due to the fact that teeth are relatively thin organs with moderate optical loss. A preliminary experiment comparing forward scattered detection with conventional back- scattered detection was carried out using an extracted human molar. The results validated the findings of the simple theoretical model and clearly showed the utility of the forward scattering geometry. The back-scattering method had readings that fluctuated by as much as 187% in response to small changes in sensor position relative to the tooth. The forward scattered method had consistent readings (within 10%) that were independent of the sensor position, a signal-to-noise ratio that was at least 5.6 times higher than the back-scattering method, and a linear response to flow rate.

  7. Effects of moderate and severe malnutrition in rats on splenic T lymphocyte subsets and activation assessed by flow cytometry

    PubMed Central

    Cortés-Barberena, E; González-Márquez, H; Gómez-Olivares, J L; Ortiz-Muñiz, R

    2008-01-01

    Malnutrition is distributed widely throughout the world and is a particular problem in developing countries. Laboratory animals have been very useful in studying the effects of varying levels of malnutrition because non-nutritional factors that affect humans may be controlled. The objective of the present study was to determine the effects of moderate and severe malnutrition on lymphocyte proportions and activation markers of T cells in experimentally malnourished rats during lactation by flow cytometry. Lower absolute (total) and relative (%) numbers of CD3+ and CD4+ lymphocyte subpopulations were observed in moderately (second degree) and severely (third degree) malnourished rats compared with well-nourished rats (P < 0·05). Both groups of malnourished rats showed a significant decrease in the percentage of CD71+ cells at 24 h post-activation with phytohaemagglutinin (PHA). After 24 h activation of spleen cells with PHA, a lower percentage of CD25+ cells was observed in malnourished than well-nourished rats (P < 0·05). In conclusion, the results of this study indicated an altered expression of CD71 and CD25 during activation of T lymphocytes in malnourished rats and may partially explain increased susceptibility to infection associated with malnutrition. Moreover, these results demonstrated that moderate malnutrition affects the response of T lymphocytes as much as severe malnutrition. PMID:18373698

  8. 40 CFR 89.415 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Fuel flow measurement specifications. 89.415 Section 89.415 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Emission Test Procedures § 89.415 Fuel flow measurement specifications. The fuel flow rate...

  9. 40 CFR 89.415 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Fuel flow measurement specifications. 89.415 Section 89.415 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Emission Test Procedures § 89.415 Fuel flow measurement specifications. The fuel flow rate...

  10. 40 CFR 89.415 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Fuel flow measurement specifications. 89.415 Section 89.415 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Emission Test Procedures § 89.415 Fuel flow measurement specifications. The fuel flow rate...

  11. 40 CFR 89.415 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Fuel flow measurement specifications. 89.415 Section 89.415 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Emission Test Procedures § 89.415 Fuel flow measurement specifications. The fuel flow rate...

  12. 40 CFR 89.415 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Fuel flow measurement specifications. 89.415 Section 89.415 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Emission Test Procedures § 89.415 Fuel flow measurement specifications. The fuel flow rate...

  13. Inertial effects at moderate Reynolds number in thin-film rimming flows driven by surface shear

    NASA Astrophysics Data System (ADS)

    Kay, E. D.; Hibberd, S.; Power, H.

    2013-10-01

    In this paper, we study two-dimensional thin-film flow inside a stationary circular cylinder driven by an imposed surface shear stress. Modelling is motivated by a need to understand the cooling and film dynamics provided by oil films in an aero-engine bearing chamber characterised by conditions of very high surface shear and additional film mass flux from oil droplets entering the film through the surface. In typical high-speed operation, film inertial effects can provide a significant leading-order mechanism neglected in existing lubrication theory models. Inertia at leading-order is included within a depth-averaged formulation where wall friction is evaluated similar to hydraulic models. This allows key nonlinear inertial effects to be included while retaining the ability to analyse the problem in a mathematically tractable formulation and compare with other approaches. In constructing this model, a set of simplified mass and momentum equations are integrated through the depth of the film yielding a spatially one-dimensional depth-averaged formulation of the problem. An a priori assumed form of velocity profile is needed to complete the system. In a local Stokes flow analysis, a quadratic profile is the exact solution for the velocity field though it must be modified when inertial effects become important. Extension of the velocity profile to a cubic profile is selected enabling specification of a wall friction model to include the roughness of the cylinder wall. A modelling advantage of including the inertia term, relevant to the applications considered, is that a smooth progression in solution can be obtained between cases of low Reynolds number corresponding to lubrication theory, and high Reynolds number corresponding to uniform rimming-flow. Importantly, we also investigate the effect of inertia on some typical solutions from other studies and present a greater insight to existing and new film solutions which arise from including inertia effects.

  14. A mean flow field solution to a moderately under/over-expanded turbulent supersonic jet

    NASA Astrophysics Data System (ADS)

    Emami, Babak; Bussmann, Markus; Tran, Honghi N.

    2009-04-01

    The linearized solution for an inviscid imperfectly-expanded supersonic axisymmetric jet has been extended to the case of a turbulent flow, by taking into account the mean Reynolds stresses. The analytical results agree reasonably well with experimental data available in the literature, and so indicate that the solution is a good approximation to the near-field of an imperfectly-expanded jet. This analytical solution could be used to improve semi-empirical models of broadband shock-associated noise in aeronautics. To cite this article: B. Emami et al., C. R. Mecanique 337 (2009).

  15. High-order numerical simulations of the flow around wings at moderately high Reynolds number

    NASA Astrophysics Data System (ADS)

    Vinuesa, Ricardo; Negi, Prabal; Hosseini, Seyed M.; Hanifi, Ardeshir; Henningson, Dan S.; Schlatter, Philipp

    2016-11-01

    The results of a DNS of the flow around a wing section represented by a NACA4412 profile, with Rec = 400 , 000 and 5° angle of attack, are presented in this study. The high-order spectral-element code Nek5000 was used for the computations. The Clauser pressure-gradient parameter β ranges from = 0 to 85 on the suction side, and the maximum Reθ and Reτ values are around 2 , 800 and 373, respectively. The adversre pressure gradient (APG) on the suction side of the wing leads to a progressively increasing value of the inner peak in the tangential velocity fluctuations, as well as the development of an outer peak, which is also observed in the other components of the Reynolds-stress tensor. Close to the trailing edge, i.e., at x / c = 0 . 9 , the outer peak in the inner-scaled tangential velocity profile is larger than the inner peak. These effects are connected to the fact that the large-scale motions of the flow become energized due to the APG, as apparent from spanwise-premultiplied power spectral density plots. Preliminary comparisons between DNS and well-resolved LES data, based on a relaxation-term filtering approach, are also presented with the aim of further extending the Reynolds number to Rec = 1 , 000 , 000 . Funded by the Swedish Research Council (VR) and the Knut and Alice Wallenberg Foundation.

  16. Some exact solutions to the Lighthill-Whitham-Richards-Payne traffic flow equations: II. Moderate congestion

    NASA Astrophysics Data System (ADS)

    Infeld, E.; Rowlands, G.; Skorupski, A. A.

    2014-10-01

    We find a further class of exact solutions to the Lighthill-Whitham- Richards-Payne (LWRP) traffic flow equations. As before, using two consecutive Lagrangian transformations, a linearization is achieved. Next, depending on the initial density, we either obtain exact formulae for the dependence of the car density and velocity on x,t, or else, failing that, the same result in a parametric representation. The calculation always involves two possible factorizations of a consistency condition. Both must be considered. In physical terms, the lineup usually separates into two offshoots at different velocities. Each velocity soon becomes uniform. This outcome in many ways resembles not only that of Rowlands et al (2013 J. Phys. A: Math. Theor. 46 365202 (part I)) but also the two-soliton solution to the Korteweg-de Vries equation. This paper can be read independently of part I. This explains unavoidable repetitions. Possible uses of both papers in checking numerical codes are indicated. Since LWRP, numerous more elaborate models, including multiple lanes, traffic jams, tollgates, etc, abound in the literature. However, we present an exact solution. These are few and far between, other than found by inverse scattering. The literature for various models, including ours, is given. The methods used here and in part I may be useful in solving other problems, such as shallow water flow.

  17. Quantitative analysis of the angular dynamics of a single spheroid in simple shear flow at moderate Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Rosén, Tomas; Nordmark, Arne; Aidun, Cyrus K.; Do-Quang, Minh; Lundell, Fredrik

    2016-08-01

    A spheroidal particle in simple shear flow shows surprisingly complicated angular dynamics; caused by effects of fluid inertia (characterized by the particle Reynolds number Rep) and particle inertia (characterized by the Stokes number St). Understanding this behavior can provide important fundamental knowledge of suspension flows with spheroidal particles. Up to now only qualitative analysis has been available at moderate Rep. Rigorous analytical methods apply only to very small Rep and numerical results lack accuracy due to the difficulty in treating the moving boundary of the particle. Here we show that the dynamics of the rotational motion of a prolate spheroidal particle in a linear shear flow can be quantitatively analyzed through the eigenvalues of the log-rolling particle (particle aligned with vorticity). This analysis provides an accurate description of stable rotational states in terms of Rep,St, and particle aspect ratio (rp). Furthermore we find that the effect on the orientational dynamics from fluid inertia can be modeled with a Duffing-Van der Pol oscillator. This opens up the possibility of developing a reduced-order model that takes into account effects from both fluid and particle inertia.

  18. Method and apparatus for coal analysis and flow measurement

    SciTech Connect

    Rollwitz, W.L.; King, J.D.

    1985-07-23

    A flow meter apparatus and method for measuring the flow, composition and heat content of coal is set forth. In the preferred and illustrated embodiment, the free or unpaired electron population of flowing coal is measured by electron magnetic resonance (EMR); the hydrogen nucleii population is measured by nuclear magnetic resonance (NMR). By calibration utilizing a standard specimen for a given type of coal, a profile for various types of coal can be obtained wherein measurement data is converted into an indication of the heat content typically measured in BTU per pound. This enables provision of a volumetric flow meter, a flow meter indicating flow in calorie content. This device enables integration to provide total heat content flow. Other variables describing the coal can be obtained.

  19. Calibration of dimensional change in finite element models using AGR moderator brick measurements

    NASA Astrophysics Data System (ADS)

    McNally, K.; Hall, G.; Tan, E.; Marsden, B. J.; Warren, N.

    2014-08-01

    Physically based models, resolved using the finite element (FE) method, are often used to model changes in geometry and the associated stress fields of graphite moderator bricks within a reactor. These models require inputs that describe the loading conditions (field variables), and coded relationships describing the behaviour of material properties. Historically, behaviour on material properties have been obtained from Materials Test Reactor (MTR) experiments, however data relating to samples trepanned from operating reactors are increasingly being used to improve models. Geometry measurements from operating reactors offer the potential for improving the coded relationship for dimensional change in FE models. A non-linear mixed-effect model is presented for calibrating the parameters of FE models that are sensitive to mid-brick diameter, using channel geometry measurements obtained from inspection campaigns. The work makes use of a novel technique: the development of a Bayesian emulator, which is a surrogate for the FE model. The use of an emulator allows the influence of the inputs to the finite element model to be evaluated, and delivers a substantial reduction in the computational burden of calibration.

  20. Measuring ice and liquid water content in moderately supercooled clouds with Cloudnet

    NASA Astrophysics Data System (ADS)

    Bühl, Johannes; Seifert, Patric; Myagkov, Alexander; Albert, Ansmann

    2016-04-01

    The interaction between ice nuclei and clouds is an important topic in weather and climate research. Recent laboratory experiments and field in-situ field campaigns present more and more detailed measurements of ice nucleating particles (INP) at temperatures close to 0°C. This brings moderately supercooled mixed-phase clouds into the focus of current cloud research. One current example is the European Union BACCHUS project. A major goal of BACCHUS is the analysis of the anthropogenic impact on ice nucleation. Within this project, we use the Leipzig Aerosol Cloud Remote Observations System (LACROS) and the Cloudnet framework in order to get quantitative insight into the formation of ice in mixed-phase layered clouds with cloud top temperature (CTT) from -40 to 0°C. Depolarization measurements from lidar and radar show a clear dependence between particle shape and the temperature under which the particles have been formed. The special focus of this work is on the CTT range from -10 to 0°C. An algorithm is presented to decide between ice and liquid water precipitation falling from the clouds showing that between 10% and 30% of all layered clouds show ice precipitation with CTT between -5 and 0°C. For these slightly supercooled clouds an average ice-water-content between 10e-7 and 10e-8 [kg per cubic meter] is found.

  1. The steady flow due to a rotating sphere at low and moderate Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Dennis, S. C. R.; Singh, S. N.; Ingham, D. B.

    1980-11-01

    The paper examines the problem of determining the steady axisymmetric motion induced by a sphere rotating with constant angular velocity about a diameter in a viscous incompressible fluid which is at rest at large distances from the diameter. The equations of motion are reduced to three sets of nonlinear second-order ordinary differential equations in the radial variable by expanding the flow variables as series of orthogonal Gegenbauer functions with argument mu = cos theta. Numerical solutions of the finite set of equations obtained by truncating the series after a given number of terms are obtained. Calculations are performed for Reynolds numbers of 1-100, and results are compared with various other theoretical results and with experimental data.

  2. Evaluation of a watershed model for estimating daily flow using limited flow measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Soil and Water Assessment Tool (SWAT) model was evaluated for estimation of continuous daily flow based on limited flow measurements in the Upper Oyster Creek (UOC) watershed. SWAT was calibrated against limited measured flow data and then validated. The Nash-Sutcliffe model Efficiency (NSE) and...

  3. System for measuring multiphase flow using multiple pressure differentials

    DOEpatents

    Fincke, James R.

    2003-01-01

    An improved method and system for measuring a multi-phase flow in a pressure flow meter. An extended throat venturi is used and pressure of the multi-phase flow is measured at three or more positions in the venturi, which define two or more pressure differentials in the flow conduit. The differential pressures are then used to calculate the mass flow of the gas phase, the total mass flow, and the liquid phase. The system for determining the mass flow of the high void fraction fluid flow and the gas flow includes taking into account a pressure drop experienced by the gas phase due to work performed by the gas phase in accelerating the liquid phase.

  4. Simulation of Five-Frequency Quasiperiodic and Related States For Convecting Flows In Moderate-Aspect-Ratio Box Geometries

    NASA Astrophysics Data System (ADS)

    Chiam, Keng-Hwee; Lai, Ming-Chih; Cross, M. C.; Greenside, Henry

    2000-11-01

    We have developed a finite-difference code to integrate the three-dimensional Boussinesq equations for Rayleigh-Bénard convection in a box geometry with insulating or conducting side walls and no-slip boundary conditions. Motivated by the experimental observations of Walden et al [Phys. Rev. Lett., 53, 242 (1984)], we used this code to study the dynamics of moderate-aspect-ratio convecting flows as a function of Rayleigh number, Prandtl number, and aspect ratio. Our simulations were able to reproduce the occurrence of quasiperiodic states with up to five incommensurate frequencies, although the values of the frequencies differ quantitatively. We find that the five-frequency state is sensitive to small perturbations to the system, breaking down to mode-locking, intermittent, and chaotic states on small changes in the Rayleigh and Prandtl numbers and aspect ratio. In particular, small changes in the aspect ratio lead to a surprisingly large multiplicity of distinct planforms yielding vastly different dynamics.

  5. 40 CFR 86.314-79 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... minimum accuracy of ±1 percent of full-scale flow rate for each measurement range used. An exception for... is ±2 percent of full-scale flow rate for each measurement range used. The controlling parameters are... of the full-scale value of the electronic device. (4) If the mass of fuel consumed is measured...

  6. 40 CFR 86.314-79 - Fuel flow measurement specifications.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... minimum accuracy of ±1 percent of full-scale flow rate for each measurement range used. An exception for... is ±2 percent of full-scale flow rate for each measurement range used. The controlling parameters are... of the full-scale value of the electronic device. (4) If the mass of fuel consumed is measured...

  7. ASRDI oxygen technology survey. Volume 6: Flow measurement instrumentation

    NASA Technical Reports Server (NTRS)

    Mann, D. B.

    1974-01-01

    A summary is provided of information available on liquid and gaseous oxygen flowmetering including an evaluation of commercial meters. The instrument types, physical principles of measurement, and performance characteristics are described. Problems concerning flow measurements of less than plus or minus two percent uncertainty are reviewed. Recommendations concerning work on flow reference systems, the use of surrogate fluids, and standard tests for oxygen flow measurements are also presented.

  8. Continuous flow measurements using fixed ultrasonic meters

    USGS Publications Warehouse

    Oltmann, Rick

    1993-01-01

    USGS has or soon will be installing four continuous flow-monitoring stations in the delta that will use ultrasonic velocity meters (DVM). Funding for the stations has been provided by USGS, DWR, USBR, and Contra Costa Water District.

  9. Experimental and Computational Study of the Flow past a Simplified Geometry of an Engine/Pylon/Wing Installation at low velocity/moderate incidence flight conditions

    NASA Astrophysics Data System (ADS)

    Bury, Yannick; Lucas, Matthieu; Bonnaud, Cyril; Joly, Laurent; ISAE Team; Airbus Team

    2014-11-01

    We study numerically and experimentally the vortices that develop past a model geometry of a wing equipped with pylon-mounted engine at low speed/moderate incidence flight conditions. For such configuration, the presence of the powerplant installation under the wing initiates a complex, unsteady vortical flow field at the nacelle/pylon/wing junctions. Its interaction with the upper wing boundary layer causes a drop of aircraft performances. In order to decipher the underlying physics, this study is initially conducted on a simplified geometry at a Reynolds number of 200000, based on the chord wing and on the freestream velocity. Two configurations of angle of attack and side-slip angle are investigated. This work relies on unsteady Reynolds Averaged Navier Stokes computations, oil flow visualizations and stereoscopic Particle Image Velocimetry measurements. The vortex dynamics thus produced is described in terms of vortex core position, intensity, size and turbulent intensity thanks to a vortex tracking approach. In addition, the analysis of the velocity flow fields obtained from PIV highlights the influence of the longitudinal vortex initiated at the pylon/wing junction on the separation process of the boundary layer near the upper wing leading-edge.

  10. Laser Doppler anemometer signal processing for blood flow velocity measurements

    SciTech Connect

    Borozdova, M A; Fedosov, I V; Tuchin, V V

    2015-03-31

    A new method for analysing the signal in a laser Doppler anemometer based on the differential scheme is proposed, which provides the flow velocity measurement in strongly scattering liquids, particularly, blood. A laser Doppler anemometer intended for measuring the absolute blood flow velocity in animal and human near-surface arterioles and venules is developed. The laser Doppler anemometer signal structure is experimentally studied for measuring the flow velocity in optically inhomogeneous media, such as blood and suspensions of scattering particles. The results of measuring the whole and diluted blood flow velocity in channels with a rectangular cross section are presented. (laser applications and other topics in quantum electronics)

  11. Transitional flow in the wake of a moderate to large height cylindrical roughness element

    NASA Astrophysics Data System (ADS)

    Plogmann, B.; Würz, W.; Krämer, E.

    2015-12-01

    The effect of an isolated, cylindrical roughness on the stability of an airfoil boundary layer has been studied based on particle image velocimetry and hot-wire anemometry. The investigated roughness elements range from a sub-critical to a super-critical behavior with regard to the critical roughness Reynolds number. For the sub-critical case, the nonlinear disturbance growth in the near wake is governed by oblique Tollmien-Schlichting (TS) type modes. Further downstream, these disturbance modes are, however, damped with the mean flow stabilization and no dominant modes persist in the far wake. By contrast, in the transitional configuration the disturbance growth is increased, but still associated with a TS-type instability in the near-wake centerline region of the low-aspect (height-to-diameter) ratio element. That is, the disturbances in the centerline region show a similar behavior as known for 2D elements, whereas in the outer spanwise domain a Kelvin-Helmholtz (KH) type, shear-layer instability is found, as previously reported for larger aspect ratio isolated elements. With increasing height and, thereby, aspect ratio of the roughness, the KH-type instability domain extends toward the centerline and, accordingly, the TS-type instability domain decreases. For high super-critical cases, transition is already triggered in the wall-normal and spanwise shear layers upstream and around the roughness. In the immediate wake, periodic shear-layer disturbances roll up into a—for isolated elements characteristic—shedding of vortices, which was not present at the lower roughness Reynolds number cases due to the decreased aspect ratio and, thereby, different instability mechanism.

  12. A process-oriented measure of habit strength for moderate-to-vigorous physical activity

    PubMed Central

    Grove, J. Robert; Zillich, Irja; Medic, Nikola

    2014-01-01

    Purpose: Habitual action is an important aspect of health behaviour, but the relevance of various habit strength indicators continues to be debated. This study focused specifically on moderate-to-vigorous physical activity (MVPA) and evaluated the construct validity of a framework emphasizing patterned action, stimulus-response bonding, automaticity, and negative consequences for nonperformance as indicators of habit strength for this form of exercise. Methods: Upper-level undergraduates (N = 124) provided demographic information and responded to questionnaire items assessing historical MVPA involvement, current MVPA involvement, and the four proposed habit strength dimensions. Factor analyses were used to examine the latent structure of the habit strength indicators, and the model's construct validity was evaluated via an examination of relationships with repetition history and current behaviour. Results: At a measurement level, findings indicated that the proposed four-component model possessed psychometric integrity as a coherent set of factors. Criterion-related validity was also demonstrated via significant changes in three of the four factors as a function of past involvement in MVPA and significant correlations with the frequency, duration, and intensity of current MVPA. Conclusions: These findings support the construct validity of this exercise habit strength model and suggest that it could provide a template for future research on how MVPA habits are developed and maintained. PMID:25750789

  13. I can't wait: Methods for measuring and moderating individual differences in impulsive choice.

    PubMed

    Peterson, Jennifer R; Hill, Catherine C; Marshall, Andrew T; Stuebing, Sarah L; Kirkpatrick, Kimberly

    2015-01-01

    Impulsive choice behavior occurs when individuals make choices without regard for future consequences. This behavior is often maladaptive and is a common symptom in many disorders, including drug abuse, compulsive gambling, and obesity. Several proposed mechanisms may influence impulsive choice behavior. These mechanisms provide a variety of pathways that may provide the basis for individual differences that are often evident when measuring choice behavior. This review provides an overview of these different pathways to impulsive choice, and the behavioral intervention strategies being developed to moderate impulsive choice. Because of the compelling link between impulsive choice behavior and the near-epidemic pervasiveness of obesity in the United States, we focus on the relationship between impulsive choice behavior and obesity as a test case for application of the multiple pathways approach. Choosing immediate gratification over healthier long term food choices is a contributing factor to the obesity crisis. Behavioral interventions can lead to more self controlled choices in a rat pre-clinical model, suggesting a possible gateway for translation to human populations. Designing and implementing effective impulsive choice interventions is crucial to improving the overall health and well-being of impulsive individuals.

  14. I can't wait: Methods for measuring and moderating individual differences in impulsive choice

    PubMed Central

    Peterson, Jennifer R.; Hill, Catherine C.; Marshall, Andrew T.; Stuebing, Sarah L.; Kirkpatrick, Kimberly

    2016-01-01

    Impulsive choice behavior occurs when individuals make choices without regard for future consequences. This behavior is often maladaptive and is a common symptom in many disorders, including drug abuse, compulsive gambling, and obesity. Several proposed mechanisms may influence impulsive choice behavior. These mechanisms provide a variety of pathways that may provide the basis for individual differences that are often evident when measuring choice behavior. This review provides an overview of these different pathways to impulsive choice, and the behavioral intervention strategies being developed to moderate impulsive choice. Because of the compelling link between impulsive choice behavior and the near-epidemic pervasiveness of obesity in the United States, we focus on the relationship between impulsive choice behavior and obesity as a test case for application of the multiple pathways approach. Choosing immediate gratification over healthier long term food choices is a contributing factor to the obesity crisis. Behavioral interventions can lead to more self controlled choices in a rat pre-clinical model, suggesting a possible gateway for translation to human populations. Designing and implementing effective impulsive choice interventions is crucial to improving the overall health and well-being of impulsive individuals. PMID:27695664

  15. Field methods for measuring concentrated flow erosion

    NASA Astrophysics Data System (ADS)

    Castillo, C.; Pérez, R.; James, M. R.; Quinton, J. N.; Taguas, E. V.; Gómez, J. A.

    2012-04-01

    techniques (3D) for measuring erosion from concentrated flow (pole, laser profilemeter, photo-reconstruction and terrestrial LiDAR) The comparison between two- and three-dimensional methods has showed the superiority of the 3D techniques for obtaining accurate cross sectional data. The results from commonly-used 2D methods can be subject to systematic errors in areal cross section that exceed magnitudes of 10 % on average. In particular, the pole simplified method has showed a clear tendency to understimate areas. Laser profilemeter results show that further research on calibrating optical devices for a variety of soil conditions must be carried out to improve its performance. For volume estimations, photo-reconstruction results provided an excellent approximation to terrestrial laser data and demonstrate that this new remote sensing technique has a promising application field in soil erosion studies. 2D approaches involved important errors even over short measurement distances. However, as well as accuracy, the cost and time requirements of a technique must be considered.

  16. Flow Measurement. Training Module 3.315.2.77.

    ERIC Educational Resources Information Center

    Kirkwood Community Coll., Cedar Rapids, IA.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with the principles of liquid flow and the methods of measuring open channel and fuel pipe flow rates. Included are objectives, instructor guides, student handouts, and transparency masters. The module addresses the basic flow formula, and…

  17. Efficiencies of intracoronary sodium nitroprusside on fractional flow reserve measurement

    PubMed Central

    Li, Shaosheng; Deng, Jie; Wang, Xiaozeng; Zhao, Xin; Han, Yaling

    2015-01-01

    Background: Fractional flow reserve (FFR) has certain advantages of assessing functional severity of coronary stenosis. Adenosine(AD) is the most widely used agents in FFR measurement but has the disadvantages of higher rate of complications. Sodium Nitroprusside (SNP) represents a valuable alternative. Methods and results: In 75 patients with 86 moderate coronary stenosis, FFR values, heart rate and blood pressure were measured at baseline, after 0.6 μg boluses of intracoronary (IC) SNP, and after 140 μg/kg /min of continuous intravenous (IV) AD. FFR values decreased significantly after administering IV AD and IC SNP compared with the baseline Pd/Pa values (P < 0.001). Mean FFR induced by IV AD was not significantly different from that by IC SNP (t = 0.577, P = 0.566). The mean kappa value in the evaluation of two methods was 0.973 for FFR. There was a significant correlation between the FFR values of IV AD and IC SNP (R = 0.911, P < 0.001). Significant decreases in the blood pressures were found after agents were given compared to the baseline. No significant difference was found between AD and SNP. In addition, immediate complications occurred in 60.5% patients of IV AD in contrast to no adverse events after IC SNP. Conclusion: SNP is a safe and effective agent and easy to use for the FFR measurement. Maximal hyperemia by IC SNP is equivalent to that by IV AD. IC SNP could be considered a potential alternative in patients with contraindications to AD administration. PMID:25932219

  18. Measurement and control systems for an imaging electromagnetic flow metre.

    PubMed

    Zhao, Y Y; Lucas, G; Leeungculsatien, T

    2014-03-01

    Electromagnetic flow metres based on the principles of Faraday's laws of induction have been used successfully in many industries. The conventional electromagnetic flow metre can measure the mean liquid velocity in axisymmetric single phase flows. However, in order to achieve velocity profile measurements in single phase flows with non-uniform velocity profiles, a novel imaging electromagnetic flow metre (IEF) has been developed which is described in this paper. The novel electromagnetic flow metre which is based on the 'weight value' theory to reconstruct velocity profiles is interfaced with a 'Microrobotics VM1' microcontroller as a stand-alone unit. The work undertaken in the paper demonstrates that an imaging electromagnetic flow metre for liquid velocity profile measurement is an instrument that is highly suited for control via a microcontroller.

  19. Wind-flow measurement over the Subaru Telescope.

    PubMed

    Horikawa, Hirofumi; Baba, Naoshi; Ohtsubo, Masashi; Norimoto, Yuji; Nishimura, Tetsuo; Miura, Noriaki

    2004-05-20

    Wind flows over the 8.2-m Subaru Telescope at Mauna Kea in Hawaii were analyzed with a correlation method. Three or four wind flows were detected from our measurements. Spatial and temporal resolution of the wind-flow analysis across the 8.2 m pupil were investigated experimentally. A three-dimensional spatiotemporal-frequency analysis was also applied to the wind-flow data.

  20. Measuring and moderating the water resource impact of biofuel production and trade

    NASA Astrophysics Data System (ADS)

    Fingerman, Kevin Robert

    Energy systems and water resources are inextricably linked, especially in the case of bioenergy, which can require up to three orders of magnitude more water than other energy carriers. Water scarcity already affects about 1 in 5 people globally, and stands to be exacerbated in many locales by current biofuel expansion plans. This dissertation engages with several of the analytical and governance challenges raised by this connection between bioenergy expansion and global water resources. My examination begins with an overview of important concepts in water resource analysis, followed by a review of current literature on the water impacts of most major energy pathways. I then report on a case study of ethanol fuel in California. This work employed a coupled agro-climatic and life cycle assessment (LCA) model to estimate the water resource impacts of several bioenergy expansion scenarios at a county-level resolution. It shows that ethanol production in California regularly consumes more than 1000 gallons of water per gallon of fuel produced, and that 99% of life-cycle water consumption occurs in the feedstock cultivation phase. This analysis then delves into the complexity of life cycle impact assessment for water resources. Despite improvements in water accounting methods, impact assessment must contend with the fact that different water sources are not necessarily commensurable, and that impacts depend on the state of the resource base that is drawn upon. I adapt water footprinting and LCA techniques to the bioenergy context, describing comprehensive inventory approaches and developing a process for characterizing (weighting) consumption values to enable comparison across resource bases. This process draws on metrics of water stress, accounting for environmental flow requirements, climatic variability, and non-linearity of water stress effects. My assessment framework was developed in hopes that it would be useful in managing the risks and impacts it describes. The

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  2. Turbulent Channel Flow Measurements Using Matched Hot-Wires

    NASA Astrophysics Data System (ADS)

    Estejab, Baraheh; Bailey, Sean

    2011-11-01

    We present an experimental study conducted in a turbulent channel flow facility using hot-wire probes with both constant and varying viscous-scaled wire length. The objectives of the study were threefold: first, to validate the flow produced by the channel flow facility; second, to investigate the validity of recently proposed spatial filtering corrections for Reynolds stress profiles; and third, to extend the investigation of the near-wall peak Reynolds number dependence in turbulent pipe flow conducted by Hultmark, Bailey and Smits (see J. Fluid Mech. (2010), vol. 649, pp. 103-113). We found that in channel flow, unlike in the pipe flow experiments, the near-wall peak exhibited the same Reynolds number dependence observed in turbulent boundary layer studies and channel flow DNS. Since the same measurement techniques and procedures were used in the current study as used in the pipe flow study, this demonstrated that the near-wall Reynolds number independence observed in the pipe study was not due to error introduced by measurement methodology. Furthermore, comparison of results from wires of different length verified that spatial filtering corrections work in channel flow as well as pipe and boundary layer flows. Corrected results were in good agreement with channel flow DNS, thus verifying that the flow in the facility approximates one-dimensional turbulent Poiseuille flow.

  3. Laser anemometer measurements in a transonic axial flow compressor rotor

    NASA Technical Reports Server (NTRS)

    Strazisar, A. J.; Powell, J. A.

    1979-01-01

    A laser anemometer system employing an efficient data acquisition technique was used to make measurements upstream, within, and downstream of the compressor rotor. A fluorescent dye technique allowed measurements within endwall boundary layers. Adjustable laser beam orientation minimized shadowed regions and enabled radial velocity measurements outside of the blade row. The flow phenomena investigated include flow variations from passage to passage, the rotor shock system, three-dimensional flows in the blade wake, and the development of the outer endwall boundary layer. Laser anemometer measurements are compared to a numerical solution of the streamfunction equations and to measurements made with conventional instrumentation.

  4. Photoacoustic Doppler flow measurement in optically scattering media

    NASA Astrophysics Data System (ADS)

    Fang, Hui; Maslov, Konstantin; Wang, Lihong V.

    2007-12-01

    We recently observed the photoacoustic Doppler effect from flowing small light-absorbing particles. Here, we apply the effect to measure blood-mimicking fluid flow in an optically scattering medium. The light scattering in the medium decreases the amplitude of the photoacoustic Doppler signal but does not affect either the magnitude or the directional discrimination of the photoacoustic Doppler shift. This technology may hold promise for a new Doppler method for measuring blood flow in microcirculation with high sensitivity.

  5. On-Orbit Lunar Modulation Transfer Function Measurements for the Moderate Resolution Imaging Spectroradiometer

    NASA Technical Reports Server (NTRS)

    Choi, Taeyong; Xiong, Xiaoxiong; Wang, Zhipeng

    2013-01-01

    Spatial quality of an imaging sensor can be estimated by evaluating its modulation transfer function (MTF) from many different sources such as a sharp edge, a pulse target, or bar patterns with different spatial frequencies. These well-defined targets are frequently used for prelaunch laboratory tests, providing very reliable and accurate MTF measurements. A laboratory-quality edge input source was included in the spatial-mode operation of the Spectroradiometric Calibration Assembly (SRCA), which is one of the onboard calibrators of the Moderate Resolution Imaging Spectroradiometer (MODIS). Since not all imaging satellites have such an instrument, SRCA MTF estimations can be used as a reference for an on-orbit lunar MTF algorithm and results. In this paper, the prelaunch spatial quality characterization process from the Integrated Alignment Collimator and SRCA is briefly discussed. Based on prelaunch MTF calibration using the SRCA, a lunar MTF algorithm is developed and applied to the lifetime on-orbit Terra and Aqua MODIS lunar collections. In each lunar collection, multiple scan-directionMoon-to-background transition profiles are aligned by the subpixel edge locations from a parametric Fermi function fit. Corresponding accumulated edge profiles are filtered and interpolated to obtain the edge spread function (ESF). The MTF is calculated by applying a Fourier transformation on the line spread function through a simple differentiation of the ESF. The lifetime lunar MTF results are analyzed and filtered by a relationship with the Sun-Earth-MODIS angle. Finally, the filtered lunarMTF values are compared to the SRCA MTF results. This comparison provides the level of accuracy for on-orbit MTF estimations validated through prelaunch SRCA measurements. The lunar MTF values had larger uncertainty than the SRCA MTF results; however, the ratio mean of lunarMTF fit and SRCA MTF values is within 2% in the 250- and 500-m bands. Based on the MTF measurement uncertainty range

  6. On acoustic intensity measurements in the presence of mean flow

    NASA Technical Reports Server (NTRS)

    Munro, D. H.; Ingard, K. U.

    1979-01-01

    A theoretical analysis demonstrates that the technique of measuring acoustic intensity by means of cross correlation between nearby microphones cannot, in general, be extended to situations in which there is mean flow. However, it may be possible to use this technique to measure intensities in ducts with mean flow at frequencies below their cutoff frequencies.

  7. Turbulence measurements in shock induced flow using hot wire anemometry

    NASA Technical Reports Server (NTRS)

    Hartung, Lin C.; Duffy, Robert E.; Trolier, James W.

    1988-01-01

    Heat transfer measurements over various geometric shapes have been made by immersing models in shock-induced flows. The heat transfer to a body is strongly dependent on the turbulence level of the stream. The interpretation of such heat transfer measurements requires a knowledge of the turbulence intensity. Turbulence intensity measurements, using hot-wire anemometry, have been successfully carried out in shock-induced flows. The experimental procedures for making such measurements and the techniques required are discussed.

  8. From steady solutions to chaotic flows in a Rayleigh-Bénard problem at moderate Rayleigh numbers

    NASA Astrophysics Data System (ADS)

    Puigjaner, D.; Herrero, J.; Simó, C.; Giralt, F.

    2011-05-01

    The dynamics of a Rayleigh-Bénard convection problem in a cubical cavity at moderate values of the Rayleigh number ( Ra≤105) and a Prandtl number of Pr=0.71 (with extensions to Pr=0.75 and 0.80) was investigated. The cubical cavity was heated from below and had perfectly conducting sidewalls and uniform temperature distributions on the two horizontal walls. A system of ordinary differential equations with a dimension of typically N≈11 000 was obtained when the conservation equations were discretized by means of a Galerkin method. Previous knowledge of the bifurcation diagram of steady solutions, reported in the literature, was used to identify the origin of several branches of periodic orbits that were continued with Ra. Half a dozen of such periodic orbits were found to be stable within narrow ranges of Ra (at most, some 5000 units wide). An attracting two-torus, restricted to a very narrow region of Ra, was also identified. It was found that the instabilization of periodic orbits quite often resulted into the development of complex dynamics such as the creation of homoclinic and heteroclinic orbits. Instances of both types of global bifurcations were analyzed in some detail. One particular instance of chaotic dynamics (a strange attractor) was also identified. Chaotic dynamics has been found at Pr=0.71 in a flow invariant subspace, which can be interpreted as a fixed-point subspace in terms of equivariant theory; this subspace is not attracting. However, some regions of attracting chaotic dynamics for moderate Rayleigh numbers ( 9×104≤Ra≤105) were found at values of Pr slightly above 0.71. The role of a particular homoclinic solution found at Pr=0.71 in the generation of these chaotic regions was analyzed.

  9. Capacitance Probe for Fluid Flow and Volume Measurements

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Nguyen, Thanh X. (Inventor); Carl, James R. (Inventor)

    1997-01-01

    Method and apparatus for making measurements on fluids are disclosed, including the use of a capacitive probe for measuring the flow volume of a material within a flow stream. The capacitance probe has at least two elongate electrodes and, in a specific embodiment of the invention, has three parallel elongate electrodes with the center electrode being an extension of the center conductor of a co-axial cable. A conductance probe is also provided to provide more accurate flow volume data in response to conductivity of the material within the flow stream. A preferred embodiment of the present invention provides for a gas flow stream through a micro-gravity environment that allows for monitoring a flow volume of a fluid sample, such as a urine sample, that is entrained within the gas flow stream.

  10. Capacitance probe for fluid flow and volume measurements

    NASA Technical Reports Server (NTRS)

    Arndt, G. Dickey (Inventor); Nguyen, Thanh X. (Inventor); Carl, James R. (Inventor)

    1995-01-01

    Method and apparatus for making measurements on fluids are disclosed, including the use of a capacitive probe for measuring the flow volume of a material within a flow stream. The capacitance probe has at least two elongate electrodes and, in a specific embodiment of the invention, has three parallel elongate electrodes with the center electrode being an extension of the center conductor of a co-axial cable. A conductance probe is also provided to provide more accurate flow volume data in response to conductivity of the material within the flow stream. A preferred embodiment of the present invention provides for a gas flow stream through a microgravity environment that allows for monitoring a flow volume of a fluid sample, such as a urine sample, that is entrained within the gas flow stream.

  11. Flow measurement in mechanical ventilation: a review.

    PubMed

    Schena, Emiliano; Massaroni, Carlo; Saccomandi, Paola; Cecchini, Stefano

    2015-03-01

    Accurate monitoring of flow rate and volume exchanges is essential to minimize ventilator-induced lung injury. Mechanical ventilators employ flowmeters to estimate the amount of gases delivered to patients and use the flow signal as a feedback to adjust the desired amount of gas to be delivered. Since flowmeters play a crucial role in this field, they are required to fulfill strict criteria in terms of dynamic and static characteristics. Therefore, mechanical ventilators are equipped with only the following kinds of flowmeters: linear pneumotachographs, fixed and variable orifice meters, hot wire anemometers, and ultrasonic flowmeters. This paper provides an overview of these sensors. Their working principles are described together with their relevant advantages and disadvantages. Furthermore, the most promising emerging approaches for flowmeters design (i.e., fiber optic technology and three dimensional micro-fabrication) are briefly reviewed showing their potential for this application.

  12. Measuring the Flow Through the Kerama Gap

    DTIC Science & Technology

    2012-09-30

    Jae-Hun Park Graduate School of Oceanography University of Rhode Island Narragansett, RI 02882-1197 Phone: 401-874-6515 & 401-874-6610 Fax...The principal flows in and out of the East China Sea (ECS) are through channels penetrating the Ryukyu Ridge (Figure 1). Since ~20 Sv of Kuroshio...Figure 1. The Ryukyu ridgeline, from Taiwan (on the left) to Kyushu, Japan (on the right). The Kerama Gap at Distance = 600 km from

  13. Evaluation of flow capture techniques for measuring HVAC grilleairflows

    SciTech Connect

    Walker, Iain S.; Wray, Craig P.

    2002-11-01

    This paper discusses the accuracy of commercially available flow hoods for residential applications. Results of laboratory and field tests indicate these hoods can be inadequate to measure airflows in residential systems, and there can be large measurement discrepancies between different flow hoods. The errors are due to poor calibrations, sensitivity of the hoods to grille airflow non-uniformities, and flow changes from added flow resistance. It is possible to obtain reasonable results using some flow hoods if the field tests are carefully done, the grilles are appropriate, and grille location does not restrict flow hood placement. We also evaluated several simple flow capture techniques for measuring grille airflows that could be adopted by the HVAC industry and homeowners as simple diagnostics. These simple techniques can be as accurate as commercially available devices. Our test results also show that current calibration procedures for flow hoods do not account for field application problems. As a result, agencies such as ASHRAE or ASTM need to develop a new standard for flow hood calibration, along with a new measurement standard to address field use of flow capture techniques.

  14. WEEE flow and mitigating measures in China.

    PubMed

    Yang, Jianxin; Lu, Bin; Xu, Cheng

    2008-01-01

    The research presented in this paper shows that Waste Electrical and Electronic Equipment (WEEE) issues associated with home appliances, such as TV sets, refrigerators, washing machines, air conditioners, and personal computers, are linked in the WEEE flow and recycling systems and are important to matters of public policy and regulation. In this paper, the sources and generation of WEEE in China are identified, and WEEE volumes are calculated. The results show that recycling capacity must increase if the rising quantity of domestic WEEE is to be handled properly. Simultaneously, suitable WEEE treatment will generate large volumes of secondary resources. Environmental problems caused by the existing recycling processes have been investigated in a case study. Problems mainly stem from open burning of plastic-metal parts and from precious metals leaching techniques that utilize acids. The existing WEEE flow at the national level was investigated and described. It became obvious that a considerable amount of obsolete items are stored in homes and offices and have not yet entered the recycling system. The reuse of used appliances has become a high priority for WEEE collectors and dealers because reuse generates higher economic profits than simple material recovery. The results of a cost analysis of WEEE flow shows that management and collection costs significantly influence current WEEE management. Heated discussions are ongoing in political and administrative bodies as to whether extended producer responsibilities policies are promoting WEEE recycling and management. This paper also discusses future challenges and strategies for WEEE management in China.

  15. MRI Based Diagnostics for Temperature Measurements in Turbulent Flows

    NASA Astrophysics Data System (ADS)

    Burton, Lauren Sascha; Elkins, Christopher J.; Eaton, John K.

    2014-11-01

    Accurate modeling of the thermal diffusion in the complex turbulent flows related to cooling high temperature gas turbine blades is critical to optimize the performance and predict the lifetime of the blades. Magnetic Resonance Imaging (MRI) techniques for temperature measurement in simple but related flows are being developed in an effort to obtain full field thermal measurements to better understand diffusion processes and support the development of more accurate computational models in these flows. Magnetic Resonance Thermometry (MRT) utilizes the temperature dependence of the hydrogen proton resonant frequency (PRF) in water. MRT is now routinely used to measure tissue temperatures during medical procedures, and a few previous studies have made velocity and temperature measurements in turbulent pipe flows. In this study, MRT is applied to the flow of a heated single hole film cooling jet (Reynolds number 3000) inclined at 30 degrees injected into a cold developing turbulent channel flow (Reynolds number 25,000 based on bulk velocity and channel height.) The jet fluid temperature is 30 degrees Celsius above the temperature in the channel. The temperature measurements compare well to previously published results for measured passive scalar concentration in the same flow although the temperature measurements show higher uncertainties of 5--10 % of the temperature difference. Techniques for reducing this uncertainty will be presented as well as procedures for applying MRT to quantify the turbulent heat transfer coefficient in turbulent internal flows.

  16. Bulk temperature measurement in thermally striped pipe flows

    SciTech Connect

    Lemure, N.; Olvera, J.R.; Ruggles, A.E.

    1995-12-01

    The hot leg flows in some Pressurized Water Reactor (PWR) designs have a temperature distribution across the pipe cross-section. This condition is often referred to as a thermally striped flow. Here, the bulk temperature measurement of pipe flows with thermal striping is explored. An experiment is conducted to examine the feasibility of using temperature measurements on the external surface of the pipe to estimate the bulk temperature of the flow. Simple mixing models are used to characterize the development of the temperature profile in the flow. Simple averaging techniques and Backward Propagating Neural Net are used to predict bulk temperature from the external temperature measurements. Accurate bulk temperatures can be predicted. However, some temperature distributions in the flow effectively mask the bulk temperature from the wall and cause significant error in the bulk temperature predicted using this technique.

  17. Time-resolved fluorescence decay measurements for flowing particles

    DOEpatents

    Deka, Chiranjit; Steinkamp, John A.

    1999-01-01

    Time-resolved fluorescence decay measurements for flowing particles. An apparatus and method for the measurement and analysis of fluorescence for individual cells and particles in flow are described, wherein the rapid measurement capabilities of flow cytometry and the robust measurement and analysis procedures of time-domain fluorescence lifetime spectroscopy are combined. A pulse-modulated cw laser is employed for excitation of the particles. The characteristics and the repetition rate of the excitation pulses can be readily adjusted to accommodate for fluorescence decays having a wide range of lifetimes.

  18. Time-resolved fluorescence decay measurements for flowing particles

    DOEpatents

    Deka, C.; Steinkamp, J.A.

    1999-06-01

    Time-resolved fluorescence decay measurements are disclosed for flowing particles. An apparatus and method for the measurement and analysis of fluorescence for individual cells and particles in flow are described, wherein the rapid measurement capabilities of flow cytometry and the robust measurement and analysis procedures of time-domain fluorescence lifetime spectroscopy are combined. A pulse-modulated CW laser is employed for excitation of the particles. The characteristics and the repetition rate of the excitation pulses can be readily adjusted to accommodate for fluorescence decays having a wide range of lifetimes. 12 figs.

  19. Measurement of two-component flow using ultrasonic flowmeters

    NASA Astrophysics Data System (ADS)

    Whitehouse, J. C.; Eghbali, D. A.; Flitton, V. E.; Anderson, D. G.

    Calibration of transit-time and Doppler ultrasonic flowmeters under two-component flow conditions has been conducted on 400 mm (16-in.) pipe. Testing covered total flows of 0.19 to 1.89 m(exp 3)/s (3000 to 30,000 gpm) and void fractions up to 40 percent. Both flowmeter types accurately measured total volumetric flow over a portion of their ranges. Pipe average void fraction, based on a three-beam gamma densitometer, was used to determine water component flow under stratified flow conditions, with similar results.

  20. Collective flow measured with the Plastic Ball

    SciTech Connect

    Ritter, H.G.; Gutbrod, H.H.; Kampert, K.H.; Kolb, B.; Poskanzer, A.M.; Schicker, R.; Schmidt, H.R.; Siemiarczuk, T.

    1989-08-01

    The experimental results from the Plastic Ball detector have contributed vastly to the understanding of the reaction mechanism of nuclear collisions at several hundred MeV per nucleon. The discovery of the collective flow phenomena (bounce-off of spectator fragments, side-splash in the reaction plane, and squeeze-out out of the reaction plane), as they were predicted by hydrodynamical models, has led to the experimental observation of compressed nuclear matter, which is a necessary condition before one can study the equation of state in detail and search for phase transitions at higher energies. 39 refs., 9 figs., 1 tab.

  1. Pulsating-flow measurement with an orifice flange

    NASA Astrophysics Data System (ADS)

    Bossart, L. M.

    1981-05-01

    A measurement problem encountered during instrumentation of a geothermal air drilling operation on the Baca Ranch in the Jemez Mountains in New Mexico was how to measure the flow of ammonia water solution injected into the air line. The pump that develops the pressure in the ammonia line is not a positive displacement pump, therefore, counting pump strokes does not determine the number of gal/min of ammonia flow. The flow was measured using an orifice flange differential pressure technique but, the range of flow measured, exceeded the 4:1 range ability of an orifice. A computer smoothing of the differential pressure and the line pressure together with a scaling factor, determined by the shape of the raw differential pressure, provided a smoothing of the flow data which was checked against the actual flow over a long time period to determine the volume of solution injected into the system per hour. An instantaneous reading of ammonia flow was thereby determined. It showed small variations in corrosion rate measured in the standpipe that may have been caused by a momentary variation in the flow of ammonia solution.

  2. Three-dimensional flow measurements in a tesla turbine rotor

    NASA Astrophysics Data System (ADS)

    Fuchs, Thomas; Schosser, Constantin; Hain, Rainer; Kaehler, Christian

    2015-11-01

    Tesla turbines are fluid mechanical devices converting flow energy into rotation energy by two physical effects: friction and adhesion. The advantages of the tesla turbine are its simple and robust design, as well as its scalability, which makes it suitable for custom power supply solutions, and renewable energy applications. To this day, there is a lack of experimental data to validate theoretical studies, and CFD simulations of these turbines. This work presents a comprehensive analysis of the flow through a tesla turbine rotor gap, with a gap height of only 0.5 mm, by means of three-dimensional Particle Tracking Velocimetry (3D-PTV). For laminar flows, the experimental results match the theory very well, since the measured flow profiles show the predicted second order parabolic shape in radial direction and a fourth order behavior in circumferential direction. In addition to these laminar measurements, turbulent flows at higher mass flow rates were investigated.

  3. Rationale for Measuring Duct Leakage Flows in Large Commercial Buildings

    SciTech Connect

    Wray, Craig P.; Diamond, Richard C.; Sherman, Max H.

    2005-07-01

    Industry-wide methods of assessing duct leakage are based on duct pressurization tests, and focus on ''high pressure'' ducts. Even though ''low pressure'' ducts can be a large fraction of the system and tend to be leaky, few guidelines or construction specifications require testing these ducts. We report here on the measured leakage flows from ten large commercial duct systems at operating conditions: three had low leakage (less than 5% of duct inlet flow), and seven had substantial leakage (9 to 26%). By comparing these flows with leakage flows estimated using the industry method, we show that the latter method by itself is not a reliable indicator of whole-system leakage flow, and that leakage flows need to be measured.

  4. A novel acoustic method for gas flow measurement using correlation techniques

    NASA Astrophysics Data System (ADS)

    Knuuttila, Matti Tapani

    The study demonstrates a new kind of acoustic method for gas flow measurement. The method uses upstream and downstream propagating low frequency plane wave and correlation techniques for volume flow rate determination. The theory of propagating low frequency plane waves in the pipe is introduced and is proved empirically to be applicable for flow measurement. The flow profile dependence of the method is verified and found to be negligible at least in the region of moderate perturbations. The physical principles of the method were applied in practice in the form of a flowmeter with new design concepts. The developed prototype meters were verified against the reference standard of NMI (Nederlands Meetinstituut), which showed that a wide dynamic range of 1:80 is achievable with total expanded uncertainty below 0.3%. Also the requirements used for turbine meters of linearity, weighted mean error and stability were shown to be well fulfilled. A brief comparison with other flowmeter types shows the new flowmeter to be competitive. The advantages it offers are a small pressure drop over the meter, no blockage of flow in possible malfunction, no pulsation to flow, essentially no moving parts, and the possibility for bidirectional measurements. The introduced flowmeter is also capable of using the introduced flowmeter is also capable of using the telephone network or a radio-modem to read the consumption of gas and report its operation to the user.

  5. Large, Moderate or Small? The Challenge of Measuring Mass Eruption Rates in Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Gudmundsson, M. T.; Dürig, T.; Hognadottir, T.; Hoskuldsson, A.; Bjornsson, H.; Barsotti, S.; Petersen, G. N.; Thordarson, T.; Pedersen, G. B.; Riishuus, M. S.

    2015-12-01

    The potential impact of a volcanic eruption is highly dependent on its eruption rate. In explosive eruptions ash may pose an aviation hazard that can extend several thousand kilometers away from the volcano. Models of ash dispersion depend on estimates of the volcanic source, but such estimates are prone to high error margins. Recent explosive eruptions, including the 2010 eruption of Eyjafjallajökull in Iceland, have provided a wealth of data that can help in narrowing these error margins. Within the EU-funded FUTUREVOLC project, a multi-parameter system is currently under development, based on an array of ground and satellite-based sensors and models to estimate mass eruption rates in explosive eruptions in near-real time. Effusive eruptions are usually considered less of a hazard as lava flows travel slower than eruption clouds and affect smaller areas. However, major effusive eruptions can release large amounts of SO2 into the atmosphere, causing regional pollution. In very large effusive eruptions, hemispheric cooling and continent-scale pollution can occur, as happened in the Laki eruption in 1783 AD. The Bárdarbunga-Holuhraun eruption in 2014-15 was the largest effusive event in Iceland since Laki and at times caused high concentrations of SO2. As a result civil protection authorities had to issue warnings to the public. Harmful gas concentrations repeatedly persisted for many hours at a time in towns and villages at distances out to 100-150 km from the vents. As gas fluxes scale with lava fluxes, monitoring of eruption rates is therefore of major importance to constrain not only lava but also volcanic gas emissions. This requires repeated measurements of lava area and thickness. However, most mapping methods are problematic once lava flows become very large. Satellite data on thermal emissions from eruptions have been used with success to estimate eruption rate. SAR satellite data holds potential in delivering lava volume and eruption rate estimates

  6. Measurement and control of pressure driven flows in microfluidic devices using an optofluidic flow sensor

    PubMed Central

    Cheri, Mohammad Sadegh; Shahraki, Hamidreza; Sadeghi, Jalal; Moghaddam, Mohammadreza Salehi; Latifi, Hamid

    2014-01-01

    Measurement and control of pressure-driven flow (PDF) has a great potential to enhance the performance of chemical and biological experiments in Lab on a Chip technology. In this paper, we present an optofluidic flow sensor for real-time measurement and control of PDF. The optofluidic flow sensor consists of an on-chip micro Venturi and two optical Fabry-Pérot (FP) interferometers. Flow rate was measured from the fringe shift of FP interferometers resulted from movement fluid in the on-chip micro Venturi. The experimental results show that the optofluidic flow sensor has a minimum detectable flow change of 5 nl/min that is suitable for real time monitoring and control of fluids in many chemical and biological experiments. A Finite Element Method is used to solve the three dimensional (3D) Navier–Stokes and continuity equations to validate the experimental results. PMID:25584118

  7. Gradient Driven Flow: Lattice Gas, Diffusion Equation and Measurement Scales

    DTIC Science & Technology

    2001-01-01

    03-200 1 Journal Article (refereed) 2001 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER Gradient Driven Flow : Lattice Gas, Diffusion Equation and...time regime, the collective motion exhibits an onset of oscillation. 15. SUBJECT TERMS Diffusion; Fick’s Law; Gradient Driven Flow ; Lattice Gas 16...Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 20010907 062 Gradient driven flow : lattice gas, diffusion equation and measurement scales R.B

  8. Microwave/Sonic Apparatus Measures Flow and Density in Pipe

    NASA Technical Reports Server (NTRS)

    Arndt, G. D.; Ngo, Phong; Carl, J. R.; Byerly, Kent A.

    2004-01-01

    An apparatus for measuring the rate of flow and the mass density of a liquid or slurry includes a special section of pipe instrumented with microwave and sonic sensors, and a computer that processes digitized readings taken by the sensors. The apparatus was conceived specifically for monitoring a flow of oil-well-drilling mud, but the basic principles of its design and operation are also applicable to monitoring flows of other liquids and slurries.

  9. Measurement of waves in flows across a surface

    NASA Technical Reports Server (NTRS)

    Kendall, Jr., James M. (Inventor)

    1992-01-01

    A method and apparatus for sensing wave flow across a surface wherein at least two pressure levels are sensed and combined to provide a representation of waves within the flow. In the preferred embodiment holes bored through the aircraft surface at an interval of one-half the wavelength of the flow being measured introduce pressure perturbations into a cavity so they may acoustically interfere. The interfering waveform is sensed by at least one microphone disposed in the cavity.

  10. Flow cytometry: A powerful technology for measuring biomarkers

    SciTech Connect

    Jett, J.H.

    1994-09-01

    A broad definition of a biomarker is that it is a measurable characteristic of a biological system that changes upon exposure to a physical or chemical insult. While the definition can be further refined, it is sufficient for the purposes of demonstrating the advantages of flow cytometry for making quantitative measurements of biomarkers. Flow cytometry and cell sorting technologies have emerged during the past 25 years to take their place alongside other essential tools used in biology such as optical and electron microscopy. This paper describes the basics of flow cytometry technology, provides illustrative examples of applications of the technology in the field of biomarkers, describes recent developments in flow cytometry that have not yet been applied to biomarker measurements, and projects future developments of the technology. The examples of uses of flow cytometry for biomarker quantification cited in this paper are meant to be illustrative and not exhaustive in the sense of providing a review of the field.

  11. AUTOMATED TECHNIQUE FOR FLOW MEASUREMENTS FROM MARIOTTE RESERVOIRS.

    USGS Publications Warehouse

    Constantz, Jim; Murphy, Fred

    1987-01-01

    The mariotte reservoir supplies water at a constant hydraulic pressure by self-regulation of its internal gas pressure. Automated outflow measurements from mariotte reservoirs are generally difficult because of the reservoir's self-regulation mechanism. This paper describes an automated flow meter specifically designed for use with mariotte reservoirs. The flow meter monitors changes in the mariotte reservoir's gas pressure during outflow to determine changes in the reservoir's water level. The flow measurement is performed by attaching a pressure transducer to the top of a mariotte reservoir and monitoring gas pressure changes during outflow with a programmable data logger. The advantages of the new automated flow measurement techniques include: (i) the ability to rapidly record a large range of fluxes without restricting outflow, and (ii) the ability to accurately average the pulsing flow, which commonly occurs during outflow from the mariotte reservoir.

  12. Device accurately measures and records low gas-flow rates

    NASA Technical Reports Server (NTRS)

    Branum, L. W.

    1966-01-01

    Free-floating piston in a vertical column accurately measures and records low gas-flow rates. The system may be calibrated, using an adjustable flow-rate gas supply, a low pressure gage, and a sequence recorder. From the calibration rates, a nomograph may be made for easy reduction. Temperature correction may be added for further accuracy.

  13. Flow among Musicians: Measuring Peak Experiences of Student Performers

    ERIC Educational Resources Information Center

    Sinnamon, Sarah; Moran, Aidan; O'Connell, Michael

    2012-01-01

    "Flow" is a highly coveted yet elusive state of mind that is characterized by complete absorption in the task at hand as well as by enhanced skilled performance. Unfortunately, because most measures of this construct have been developed in physical activity and sport settings, little is known about the applicability of flow scales to the…

  14. Project Themis: PIV Measurement of Elbow Flow through a Flow Conditioner

    DTIC Science & Technology

    2011-12-01

    Charts 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Project Themis: PIV Measurement of Elbow Flow through a Flow...Project Themis: PIV Measurement of Elbow Flow through a Flow Conditioner Benjamin Miller AFRL/RZSE (Jackson and Tull) Air Force Research...Max power = 20mJ @ 1kHz • Phantom V210 • 2,000 frames per second 45 CFM hose 90 ̊ long curve elbow VORTAB L/D = 30 • VORTAB placed one

  15. PIV measurements of flow in a centrifugal blood pump: steady flow.

    PubMed

    Day, Steven W; McDaniel, James C

    2005-04-01

    Magnetically suspended left ventricular assist devices have only one moving part, the impeller. The impeller has absolutely no contact with any of the fixed parts, thus greatly reducing the regions of stagnant or high shear stress that surround a mechanical or fluid bearing. Measurements of the mean flow patterns as well as viscous and turbulent stresses were made in a shaft-driven prototype of a magnetically suspended centrifugal blood pump at several constant flow rates (3-9 L/min) using particle image velocimetry (PIV). The chosen range of flow rates is representative of the range over which the pump may operate while implanted. Measurements on a three-dimensional measurement grid within several regions of the pump, including the inlet, blade passage, exit volute, and diffuser are reported. The measurements are used to identify regions of potential blood damage due to high shear stress and/or stagnation of the blood, both of which have been associated with blood damage within artificial heart valves and diaphragm-type pumps. Levels of turbulence intensity and Reynolds stresses that are comparable to those in artificial heart valves are reported. At the design flow rate (6 L/min), the flow is generally well behaved (no recirculation or stagnant flow) and stress levels are below levels that would be expected to contribute to hemolysis or thrombosis. The flow at both high (9 L/min) and low (3 L/min) flow rates introduces anomalies into the flow, such as recirculation, stagnation, and high stress regions. Levels of viscous and Reynolds shear stresses everywhere within the pump are below reported threshold values for damage to red cells over the entire range of flow rates investigated; however, at both high and low flow rate conditions, the flow field may promote activation of the clotting cascade due to regions of elevated shear stress adjacent to separated or stagnant flow.

  16. PIV measurements of flow in a centrifugal blood pump: time-varying flow.

    PubMed

    Day, Steven W; McDaniel, James C

    2005-04-01

    Measurements of the time-varying flow in a centrifugal blood pump operating as a left ventricular assist device (LVAD) are presented. This includes changes in both the pump flow rate as a function of the left ventricle contraction and the interaction of the rotating impeller and fixed exit volute. When operating with a pulsing ventricle, the flow rate through the LVAD varies from 0-11 L/min during each cycle of the heartbeat. Phase-averaged measurements of mean velocity and some turbulence statistics within several regions of the pump, including the inlet, blade passage, exit volute, and diffuser, are reported at 20 phases of the cardiac cycle. The transient flow fields are compared to the constant flow rate condition that was reported previously in order to investigate the transient effects within the pump. It is shown that the quasi-steady assumption is a fair treatment of the time varying flow field in all regions of this representative pump, which greatly simplifies the comprehension and modeling of this flow field. The measurements are further interpreted to identify the effects that the transient nature of the flow field will have on blood damage. Although regions of recirculation and stagnant flow exist at some phases of the cardiac cycle, there is no location where flow is stagnant during the entire heartbeat.

  17. Measurements of granular flow dynamics with high speed digital images

    SciTech Connect

    Lee, J.

    1994-12-31

    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.

  18. Measurement of directed blood flow by laser speckle

    NASA Astrophysics Data System (ADS)

    Hirst, Evan R.; Thompson, Oliver B.; Andrews, Michael K.

    2011-03-01

    Recent success in reconciling laser Doppler and speckle measurements of dermal perfusion by the use of multi-exposure speckle has prompted an investigation of speckle effects arising from directed blood flow which might be expected in the small blood vessels of the eye. Unlike dermal scatter, the blood in retinal vessels is surrounded by few small and stationary scatterers able to assist the return of light energy by large-angle scatter. Returning light is expected to come from multiple small angle scatter from the large red blood cells which dominate the fluid. This work compares speckle measurements on highly scattering skin, with measurements on flow in a retinal phantom consisting of a glass capillary which is itself immersed in an index matching fluid to provide a flat air-phantom interface. Brownian motion dominated measurements when small easily levitated scatters were used, and flow was undetectable. With whole-blood, Brownian motion was small and directed flows in the expected region of tens of mm/s were detectable. The nominal flow speed relates to the known pump rate; within the capillary the flow will have a profile reducing toward the walls. The pulsatile effects on laser speckle contrast in the retina are discussed with preliminary multi-exposure measurements on retinal vessels using a fundus camera. Differences between the multiple exposure curves and power spectra of perfused tissue and ordered flow are discussed.

  19. Exploratory flexural power flow measurements on a bar

    NASA Astrophysics Data System (ADS)

    Vanderwal, H. M. M.

    1990-05-01

    Exploratory experiments in a bar with an absorptive termination were performed. The bar was excited in a transversal direction. The flexural power flow in the bar was measured at various positions, applying the two transducer technique (2TT) and the four transducer technique (4TT). The separation distance between the accelerometers was varied. The power flow at the excitation point was determined from a force and an acceleration measurement (Fv). When comparing the 2TT power flow with the 4TT or Fv power flow, the discretization error (i.e. the error due to a finite accelerometer separation) is an important parameter, particularly for separations larger than one sixth of a wavelength. In order to quantify the effect of this error, a prediction of the measured power flows on the basis of an analytical solution of the bending wave equation for the far field is performed. For most cases a good agreement is found between the predicted and the measured power flow ratios (i.e. 4TT/2TT and 2TT/Fv). However, for accelerometer separations smaller than about one sixth of a wavelength, a larger scatter is observed in the power flow data, measured with the 4TT, due to loss of significant digits. This effect may result in limitations for multiple transducer techniques in two or three dimensional structures.

  20. Measurement of limb blood flow by electrical impedance plethysmography.

    PubMed Central

    Porter, J. M.; Swain, I. D.; Shakespeare, P. G.

    1985-01-01

    Limb blood flow has been measured in 72 individuals by the noninvasive technique of electrical impedance plethysmography. Venous occlusion was not used. Blood flow was measured in 230 limbs in which 195 limbs were either in normal individuals or the clinically normal limbs of patients (normal limbs). Thirty-five limbs were clinically abnormal. Measurements on limbs with clinical abnormalities showed that blood flow values often fell within the limits of the normal range. However 3 cases of known vascular injury and 2 cases studied after hand surgery under tourniquet showed lowered blood flow values by comparison with the unaffected limb. A simultaneously recorded range of cardiac output and stroke volume measurements gave similar results to those obtained in a previous, unconnected study. Images Fig. 1 PMID:4004047

  1. Enhanced Oil Recovery: Aqueous Flow Tracer Measurement

    SciTech Connect

    Joseph Rovani; John Schabron

    2009-02-01

    A low detection limit analytical method was developed to measure a suite of benzoic acid and fluorinated benzoic acid compounds intended for use as tracers for enhanced oil recovery operations. Although the new high performance liquid chromatography separation successfully measured the tracers in an aqueous matrix at low part per billion levels, the low detection limits could not be achieved in oil field water due to interference problems with the hydrocarbon-saturated water using the system's UV detector. Commercial instrument vendors were contacted in an effort to determine if mass spectrometry could be used as an alternate detection technique. The results of their work demonstrate that low part per billion analysis of the tracer compounds in oil field water could be achieved using ultra performance liquid chromatography mass spectrometry.

  2. Planetary heat flow from shallow subsurface measurements: Mars

    NASA Astrophysics Data System (ADS)

    Cornwall, Marc; Hagermann, Axel

    2016-10-01

    Planetary heat flow probes measure heat flow (depth-resolved temperature and thermal conductivity) to provide insight into the internal state of a planet. The probes have been utilized extensively on Earth, twice on the Moon, and once on the Surface of comet 67P-CG. Mars is an important target for heat flow measurement as heat flow is a critical parameter in Martian thermal history models. Earlier studies indicate that Martian planetary heat flow can be accessed at 5 m below the surface in dry regolith monitored over at least one Martian year. A one Martian year monitoring period is necessary because, in the shallow subsurface, heat flow from the interior is superposed with time varying heat flow contributions, primarily due to insolation. Given that a heat flow probe may not achieve its target depth or monitoring period, this study investigates how the depth (2-5 m), duration (0-1 Martian year) and quality of measurements influence the accuracy of planetary heat flow. An inverse model is used to show that, in the preceding scenarios, the accuracy of planetary heat flow directly estimated from depth-dependent thermal conductivity with 10-20% precision errors, temperatures with 50-100 mK precision errors and modelling uncertainties up to 500 mK, can, on average, be improved by a factor of 27 with optimization to 13%. Accuracies increase with sensor penetration depth and regolith monitoring period. Heat flow optimized from instantaneous measurements or those with the shortest regolith monitoring periods have increased accuracy where the frequency and amplitude of the temperature variation are lowest. The inverse model is based on the Function Specification Inversion method. This study demonstrates that a solution subspace can be identified within a space of uncertainties modelled for the temperature measurements and planetary heat flow: the subspace is defined by a constant log-ratio of their respective standard deviations. Optimized heat flow estimates display

  3. Filtered Rayleigh Scattering Measurements in a Buoyant Flow Field

    DTIC Science & Technology

    2008-03-01

    John William Strutt , the third Baron of Rayleigh , or more commonly known as Lord Rayleigh , was the first to offer a correct explanation of the...FILTERED RAYLEIGH SCATTERING MEASUREMENTS IN A BUOYANT FLOW FIELD         THESIS       Steven Michael Meents, Captain, USAF...AFIT/GAE/ENY/08-M22 FILTERED RAYLEIGH SCATTERING MEASUREMENTS IN A BUOYANT FLOW FIELD THESIS Presented to the Faculty Department of Aeronautics

  4. In vitro flow measurements in ion sputtered hydrocephalus shunts

    NASA Technical Reports Server (NTRS)

    Cho, Y. I.; Back, L. H.

    1989-01-01

    This paper describes an experimental procedure for accurate measurements of the pressure-drop/flow rate relationship in hydrocephalus shunts. Using a fish-hook arrangement, small flow rates in a perforated ion-sputtered Teflon microtubule were measured in vitro in a pressured system and were correlated with pressure in the system. Results indicate that appropriate drainage rates could be obtained in the physiological range for hydrocephalus shunts.

  5. Flow measurements in a water tunnel using a holocinematographic velocimeter

    NASA Technical Reports Server (NTRS)

    Weinstein, Leonard M.; Beeler, George B.

    1987-01-01

    Dual-view holographic movies were used to examine complex flows with full three-space and time resolution. This approach, which tracks the movement of small tracer particles in water, is termed holocinematographic velocimetry (HCV). A small prototype of a new water tunnel was used to demonstrate proof-of-concept for the HCV. After utilizing a conventional flow visualization apparatus with a laser light sheet to illuminate tracer particles to evaluate flow quality of the prototype tunnel, a simplified version of the HCV was employed to demonstrate the capabilities of the approach. Results indicate that a full-scale version of the water tunnel and a high performance version of the HCV should be able to check theoretical and numerical modeling of complex flows and examine the mechanisms operative in turbulent and vortex flow control concepts, providing an entirely unique instrument capable, for the first time, of simultaneous three-space and time measurements in turbulent flow.

  6. Flow measurements in a water tunnel using a holocinematographic velocimeter

    NASA Astrophysics Data System (ADS)

    Weinstein, Leonard M.; Beeler, George B.

    1987-06-01

    Dual-view holographic movies were used to examine complex flows with full three-space and time resolution. This approach, which tracks the movement of small tracer particles in water, is termed holocinematographic velocimetry (HCV). A small prototype of a new water tunnel was used to demonstrate proof-of-concept for the HCV. After utilizing a conventional flow visualization apparatus with a laser light sheet to illuminate tracer particles to evaluate flow quality of the prototype tunnel, a simplified version of the HCV was employed to demonstrate the capabilities of the approach. Results indicate that a full-scale version of the water tunnel and a high performance version of the HCV should be able to check theoretical and numerical modeling of complex flows and examine the mechanisms operative in turbulent and vortex flow control concepts, providing an entirely unique instrument capable, for the first time, of simultaneous three-space and time measurements in turbulent flow.

  7. Cyclic Concentration Measurements for Characterizing Pulsating Flow

    SciTech Connect

    Bamberger, Judith A.

    2013-07-07

    Slurry mixed in vessels via pulse jet mixers has a periodic, rather than steady, concentration profile. Measurements of local concentration taken at the center of the tank at a range of elevations within the mixed region were analyzed to obtain a greater understanding of how the periodic pulse jet mixing cycle affects the local concentration. Data were obtained at the critical suspension velocity, when all solids are suspended at the end of the pulse. The data at a range of solids loadings are analyzed to observe the effect of solids concentration during the suspension and settling portions of the mixing cycle.

  8. Measurement system design of an imaging electromagnetic flow meter

    NASA Astrophysics Data System (ADS)

    Zhao, Y. Y.; Lucas, G.; Leeungculsatien, T.; Zhang, T.

    2012-03-01

    Electromagnetic flow meters based on the principles of Faraday's laws of induction have been used successfully in many industries. In order to achieve velocity profile measurements in single phase and multiphase flows with non-uniform velocity profiles, a novel Imaging Electromagnetic Flow meter (IEF) has been developed which is described in this paper. The novel electromagnetic flow meter uses a microcontroller as the processing core to achieve the function of driving the uniform magnetic field, acquiring voltage signals with electronic system, matrix inversion calculation and result display. The work undertaken in the paper demonstrates that an imaging electromagnetic flow meter for liquid velocity profile measurement is an instrument that is highly suited for control via a microcontroller.

  9. PIV measurements of hydrodynamic interactions between biofilms and flow

    NASA Astrophysics Data System (ADS)

    Christensen, Kenneth T.; Kazemifar, Farzan; Aybar, Marcelo; Perez-Calleja, Patricia; Nerenberg, Robert; Sinha, Sumit; Hardy, Richard J.; Best, Jim L.; Sambrook Smith, Greg H.

    2015-11-01

    Biofilms constitute an important form of bacterial life in aquatic environments and are present at the interface of fluids and solid such as riverbeds or bridge columns. They are also utilized in bioreactors for bioremediation and water treatment purposes. They are permeable, heterogeneous, and deformable structures that can influence the flow and mass/momentum transport, yet their interaction with flow is not fully understood in part due to technical obstacles impeding quantitative experimental investigations. We have attempted to address these challenges using the PIV technique and fluorescence imaging to investigate the flow field around cylinders covered with biofilms at different growth stages. These measurements are meant to uncover the coupled dynamics of turbulence and the biofilm development. Preliminary results of PIV measurements of flow-biofilm interactions in channel flow will be presented.

  10. Flap survey test of a combined surface blowing model: Flow measurements at static flow conditions

    NASA Technical Reports Server (NTRS)

    Fukushima, T.

    1978-01-01

    The Combined Surface Blowing (CSB) V/STOL lift/propulsion system consists of a blown flap system which deflects the exhaust from a turbojet engine over a system of flaps deployed at the trailing edge of the wing. Flow measurements consisting of velocity measurements using split film probes and total measure surveys using a miniature Kiel probe were made at control stations along the flap systems at two spanwise stations, the centerline of the nozzle and 60 percent of the nozzle span outboard of the centerline. Surface pressure measurements were made in the wing cove and the upper surface of the first flap element. The test showed a significant flow separation in the wing cove. The extent of the separation is so large that the flow into the first flap takes place only at the leading edge of the flap. The velocity profile measurements indicate that large spanwise (3 dimensional) flow may exist.

  11. Rarefield gas flows through meshes and implications for atmospheric measurements

    NASA Astrophysics Data System (ADS)

    Gumbel, J.

    2001-05-01

    Meshes are commonly used as part of instruments for in situ atmospheric measurements. This study analyses the aerodynamic effect of meshes by means of wind tunnel experiments and numerical simulations. Based on the Direct Simulation Monte Carlo method, a simple mesh parameterisation is described and applied to a number of representative flow conditions. For open meshes freely exposed to the flow, substantial compression effects are found both upstream and downstream of the mesh. Meshes attached to close instrument structures, on the other hand, cause only minor flow disturbances. In an accompanying paper, the approach developed here is applied to the quantitative analysis of rocket-borne density measurements in the middle atmosphere.

  12. Process tomography applied to multi-phase flow measurement

    NASA Astrophysics Data System (ADS)

    Dyakowski, T.

    1996-03-01

    This paper presents the state of the art in measuring multi-phase flows by using tomographic techniques. The results presented show a wide range of industrial applications of process tomography from the nuclear and chemical to the food industry. This is illustrated by examples of the application of various tomographic sensors to the measurement of geometric or kinematic parameters of multi-phase flows. An application of process tomography for the validation of computational fluid dynamic models and the possibility of constructing a flowmeter for multi-phase flow are addressed.

  13. Guide to Flow Measurement for Electric Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Frieman, Jason D.; Walker, Mitchell L. R.; Snyder, Steve

    2013-01-01

    In electric propulsion (EP) systems, accurate measurement of the propellant mass flow rate of gas or liquid to the thruster and external cathode is a key input in the calculation of thruster efficiency and specific impulse. Although such measurements are often achieved with commercial mass flow controllers and meters integrated into propellant feed systems, the variability in potential propellant options and flow requirements amongst the spectrum of EP power regimes and devices complicates meter selection, integration, and operation. At the direction of the Committee on Standards for Electric Propulsion Testing, a guide was jointly developed by members of the electric propulsion community to establish a unified document that contains the working principles, methods of implementation and analysis, and calibration techniques and recommendations on the use of mass flow meters in laboratory and spacecraft electric propulsion systems. The guide is applicable to EP devices of all types and power levels ranging from microthrusters to high-power ion engines and Hall effect thrusters. The establishment of a community standard on mass flow metering will help ensure the selection of the proper meter for each application. It will also improve the quality of system performance estimates by providing comprehensive information on the physical phenomena and systematic errors that must be accounted for during the analysis of flow measurement data. This paper will outline the standard methods and recommended practices described in the guide titled "Flow Measurement for Electric Propulsion Systems."

  14. Heat transfer measurements of the 1983 kilauea lava flow.

    PubMed

    Hardee, H C

    1983-10-07

    Convective heat flow measurements of a basaltic lava flow were made during the 1983 eruption of Kilauea volcano in Hawaii. Eight field measurements of induced natural convection were made, giving heat flux values that ranged from 1.78 to 8.09 kilowatts per square meter at lava temperatures of 1088 and 1128 degrees Celsius, respectively. These field measurements of convective heat flux at subliquidus temperatures agree with previous laboratory measurements in furnace-melted samples of molten lava, and are useful for predicting heat transfer in magma bodies and for estimating heat extraction rates for magma energy.

  15. Heat-transfer measurements of the 1983 Kilauea lava flow

    SciTech Connect

    Hardee, H.C.

    1983-10-07

    Convective heat flow measurements of a basaltic lava flow were made during the 1983 eruption of Kilauea volcano in Hawaii. Eight field measurements of induced natural convection were made, giving heat flux values that ranged from 1.78 to 8.09 kilowatts per square meter at lava temperatures of 1088 and 1128 degrees Celsius, respectively. These field measurements of convective heat flux at subliquidus temperatures agree with previous laboratory measurements in furnace-melted samples of molten lava, and are useful for predicting heat transfer in magma bodies and for estimating heat extraction rates for magma energy.

  16. Induced airflow in flying insects II. Measurement of induced flow.

    PubMed

    Sane, Sanjay P; Jacobson, Nathaniel P

    2006-01-01

    The flapping wings of insects and birds induce a strong flow over their body during flight. Although this flow influences the sensory biology and physiology of a flying animal, there are very little data on the characteristics of this self-generated flow field or its biological consequences. A model proposed in the companion paper estimated the induced flow over flying insects. In this study, we used a pair of hot wire anemometers to measure this flow at two locations near the body of a tethered flapping hawk moth, Manduca sexta. The axial inflow anemometer measured the airflow prior to its entry into the stroke plane, whereas the radial outflow anemometer measured the airflow after it crossed the stroke plane. The high temporal resolution of the hot wire anemometers allowed us to measure not only the mean induced flow but also subtle higher frequency disturbances occurring at 1-4 times the wing beat frequency. These data provide evidence for the predictions of a mathematical model proposed in the companion paper. Specifically, the absolute value of the measured induced flow matches the estimate of the model. Also, as predicted by the model, the induced flow varies linearly with wing beat frequency. Our experiments also show that wing flexion contributes significantly to the observed higher frequency disturbances. Thus, the hot wire anemometry technique provides a useful means to quantify the aerodynamic signature of wing flexion. The phasic and tonic components of induced flow influence several physiological processes such as convective heat loss and gas exchange in endothermic insects, as well as alter the nature of mechanosensory and olfactory stimuli to the sensory organs of a flying insect.

  17. Time-Resolved Rayleigh Scattering Measurements in Hot Gas Flows

    NASA Technical Reports Server (NTRS)

    Mielke, Amy F.; Elam, Kristie A.; Sung, Chih-Jen

    2008-01-01

    A molecular Rayleigh scattering technique is developed to measure time-resolved gas velocity, temperature, and density in unseeded gas flows at sampling rates up to 32 kHz. A high power continuous-wave laser beam is focused at a point in an air flow field and Rayleigh scattered light is collected and fiber-optically transmitted to the spectral analysis and detection equipment. The spectrum of the light, which contains information about the temperature and velocity of the flow, is analyzed using a Fabry-Perot interferometer. Photomultipler tubes operated in the photon counting mode allow high frequency sampling of the circular interference pattern to provide time-resolved flow property measurements. Mean and rms velocity and temperature fluctuation measurements in both an electrically-heated jet facility with a 10-mm diameter nozzle and also in a hydrogen-combustor heated jet facility with a 50.8-mm diameter nozzle at NASA Glenn Research Center are presented.

  18. Thomson scattering measurements from asymmetric interpenetrating plasma flows

    SciTech Connect

    Ross, J. S. Moody, J. D.; Fiuza, F.; Ryutov, D.; Divol, L.; Huntington, C. M.; Park, H.-S.

    2014-11-15

    Imaging Thomson scattering measurements of collective ion-acoustic fluctuations have been utilized to determine ion temperature and density from laser produced counter-streaming asymmetric flows. Two foils are heated with 8 laser beams each, 500 J per beam, at the Omega Laser facility. Measurements are made 4 mm from the foil surface using a 60 J 2ω probe laser with a 200 ps pulse length. Measuring the electron density and temperature from the electron-plasma fluctuations constrains the fit of the multi-ion species, asymmetric flows theoretical form factor for the ion feature such that the ion temperatures, ion densities, and flow velocities for each plasma flow are determined.

  19. Effects of nonuniform acceptance in anisotropic flow measurements

    SciTech Connect

    Selyuzhenkov, Ilya; Voloshin, Sergei

    2008-03-15

    The applicability of anisotropic flow measurement techniques and their extension for detectors with nonuniform azimuthal acceptance are discussed. Considering anisotropic flow measurements with two and three (mixed harmonic) azimuthal correlations we introduce a set of observables based on the x and y components of the event flow vector. These observables provide independent measures of anisotropic flow and can be used to test the self-consistency of the analysis. Based on these observables we propose a technique that explicitly takes into account the effects of nonuniform detector acceptance. Within this approach the acceptance corrections, as well as parameters that define the method applicability, can be determined directly from experimental data. For practical purposes a brief summary of the method is provided at the end.

  20. Velocity Measurements of Turbulent Wake Flow Over a Circular Cylinder

    NASA Astrophysics Data System (ADS)

    Shih, Chang-Lung; Chen, Wei-Cheng; Chang, Keh-Chin; Wang, Muh-Rong

    2016-06-01

    There are two general concerns in the velocity measurements of turbulence. One is the temporal characteristics which governs the turbulent mixing process. Turbulence is rotational and is characterized by high levels of fluctuating vorticity. In order to obtain the information of vorticity dynamics, the spatial characteristics is the other concern. These varying needs can be satisfied by using a variety of diagnostic techniques such as invasive physical probes and non-invasive optical instruments. Probe techniques for the turbulent measurements are inherently simple and less expensive than optical methods. However, the presence of a physical probe may alter the flow field, and velocity measurements usually become questionable when probing recirculation zones. The non-invasive optical methods are mostly made of the foreign particles (or seeding) instead of the fluid flow and are, thus, of indirect method. The difference between the velocities of fluid and foreign particles is always an issue to be discussed particularly in the measurements of complicated turbulent flows. Velocity measurements of the turbulent wake flow over a circular cylinder will be made by using two invasive instruments, namely, a cross-type hot-wire anemometry (HWA) and a split-fiber hot-film anemometry (HFA), and a non-invasive optical instrument, namely, particle image velocimetry (PIV) in this study. Comparison results show that all three employed diagnostic techniques yield similar measurements in the mean velocity while somewhat deviated results in the root-mean-squared velocity, particularly for the PIV measurements. It is demonstrated that HFA possesses more capability than HWA in the flow measurements of wake flow. Wake width is determined in terms of either the flatness factor or shear-induced vorticity. It is demonstrated that flow data obtained with the three employed diagnostic techniques are capable of yielding accurate determination of wake width.

  1. Measurements of the tip-gap turbulent flow structure in a low-speed compressor cascade

    NASA Astrophysics Data System (ADS)

    Tang, Genglin

    This dissertation presents results from a thorough study of the tip-gap turbulent flow structure in a low-speed linear compressor cascade wind tunnel at Virginia Tech that includes a moving belt system to simulate the relative motion between the tip and the casing. The endwall pressure measurements and the surface oil flow visualizations were made on a stationary endwall to obtain the flow features and to determine the measurement profiles of interest. A custom-made miniature 3-orthogonal-velocity-component fiber-optic laser-Doppler velocimetry (LDV) system was used to measure all three components of velocity within a 50 mum spherical measurement volume within the gap between the endwall and the blade tip, mainly for the stationary wall with 1.65% and 3.30% tip gaps as well as some initial experiments for the moving wall. Since all of the vorticity in a flow originates from the surfaces under the action of strong pressure gradient, it was very important to measure the nearest-wall flow on the endwall and around the blade tip. The surface skin friction velocity was measured by using viscous sublayer velocity profiles, which verified the presence of an intense lateral shear layer that was observed from surface oil flow visualizations. All second- and third-order turbulence quantities were measured to provide detailed data for any parallel CFD efforts. The most complete data sets were acquired for 1.65% and 3.30% tip gap/chord ratios in a low-speed linear compressor cascade. This study found that tip gap flows are complex pressure-driven, unsteady three-dimensional turbulent flows. The crossflow velocity normal to the blade chord is nearly uniform in the and tip-gap and changes substantially from the pressure to suction side. The crossflow velocity relies on the local tip pressure loading that is different from the mid-span pressure loading because of tip leakage vortex influence. The tip gap flow is highly skewed three-dimensional flow throughout the full gap

  2. Clean seeding for flow visualization and velocimetry measurements

    NASA Astrophysics Data System (ADS)

    Reeder, Mark F.; Crafton, Jim W.; Estevadeordal, Jordi; Delapp, Joseph; McNiel, Charles; Peltier, Don; Reynolds, Tina

    2010-05-01

    Flow visualization, particle image velocimetry (PIV), and laser Doppler velocimetry (LDV) are among the most useful tools available for experimental aerodynamics studies. Implementation of these techniques, however, requires that seed material be introduced into the flow. The undesirable qualities of the seeding material often prevent the use of flow visualization and velocimetry techniques in many test environments. This is particularly true for large-scale, closed-circuit tunnels where facility operators must weigh the risks of facility contamination, sensor damage, and safety concerns that might result from the introduction of seed particles. Identification of a practical clean seeding material that minimizes or eliminates these concerns would enable flow visualization and velocimetry techniques to be deployed in these facilities. Here, we demonstrate two seeding systems that have the potential to provide such a solution. The first system is a new concept which uses liquid carbon dioxide that can be made to form discrete particles as it expands from a high-pressure tank. PIV measurements are demonstrated in several flows, including supersonic and subsonic tunnels, using these residue-free seed particles. The second system utilizes a combination of steam and liquid nitrogen to produce an aerosol or fog that serves as flow seeding. Water- or steam-based seeding has been previously demonstrated for flow visualization in subsonic tunnels; here however, we utilize this seed material for PIV and LDV measurements as well as for flow visualization in a large supersonic tunnel.

  3. Flow Field Measurement of Mixing Driven by Buoyancy

    NASA Technical Reports Server (NTRS)

    Batur, C.; Zhong, H.

    2003-01-01

    Mixing driven by buoyancy-induced flows inside a cavity consists of stretching and folding of an interface. Measurement of the flow field using particle imaging velocimetry shows that during stretching the flow field has a single elliptic point, thus dominated by a single vortex. However, global bifurcation that results in folding introduces a hyperbolic point whereby the flow field degenerates to multiple vortex interactions. The short-lived coherent structure observed during mixing which results in the Rayleigh- Taylor morphology is attributed to vortex interactions. The mixing characteristics of non-homogeneous fluids driven by buoyancy are important towards understanding transport phenomenon in a microgravity environment. Mixing consists of stretching and folding of an interface due to a flow field whose intensity depends on the body force. For miscible liquids, the characteristic of the flow field determines whether mass transport is governed by diffusion or bulk stirring which induces mixing. For technologically important processes, transport of mass is governed by the coupling of the body force to scalar gradients such as concentration and or temperature' 2 3 . In order to lend insight into these classes of problems we consider a model experimental system to study mixing driven by buoyancy-induced flows. The characteristics of mixing is addressed from detail measurements of the flow field using particle imaging velocimetry (PIV), and its corresponding interface dynamics using image processing techniques.

  4. Volumetric Flow Measurement Using an Implantable CMUT Array.

    PubMed

    Mengli Wang; Jingkuang Chen

    2011-06-01

    This paper describes volumetric-flow velocity measurement using an implantable capacitive micromachined ultrasonic transducer (CMUT) array. The array is comprised of multiple-concentric CMUT rings for ultrasound transmission and an outmost annular CMUT array for ultrasound reception. Microelectromechanical-system (MEMS) fabrication technology allows reception CMUT on this flowmeter to be implemented with a different membrane thickness and gap height than that of transmission CMUTs, optimizing the performance of these two different kinds of devices. The silicon substrate of this 2-mm-diameter CMUT ring array was bulk micromachined to approximately 80 to 100 μm thick, minimizing tissue disruption. The blood-flow velocity was detected using pulse ultrasound Doppler by comparing the demodulated echo ultrasound with the incident ultrasound. The demodulated ultrasound signal was sampled by a pulse delayed in time domain from the transmitted burst, which corresponds to detecting the signal at a specific distance. The flow tube/vessel diameter was detected through the time-flight delay difference from near and far wall reflections, which was measured from the ultrasound pulse echo. The angle between the ultrasound beam and the flow was found by using the cross-correlation from consecutive ultrasound echoes. Artificial blood flowing through three different polymer tubes was experimented with, while keeping the same volumetric flow rate. The discrepancy in flow measurement results between this CMUT meter and a calibrated laser Doppler flowmeter is less than 5%.

  5. A thermal stack structure for measurement of fluid flow

    NASA Astrophysics Data System (ADS)

    Zhao, Hao; Mitchell, S. J. N.; Campbell, D. H.; Gamble, Harold S.

    2003-03-01

    A stacked thermal structure for fluid flow sensing has been designed, fabricated, and tested. A double-layer polysilicon process was employed in the fabrication. Flow measurement is based on the transfer of heat from a temperature sensor element to the moving fluid. The undoped or lightly doped polysilicon temperature sensor is located on top of a heavily doped polysilicon heater element. A dielectric layer between the heater and the sensor elements provides both thermal coupling and electrical isolation. In comparison to a hot-wire flow sensor, the heating and sensing functions are separated, allowing the electrical characteristics of each to be optimized. Undoped polysilicon has a large temperature coefficient of resistance (TCR) up to 7 %/K and is thus a preferred material for the sensor. However, heavily doped polysilicon is preferred for the heater due to its lower resistance. The stacked flow sensor structure offers a high thermal sensitivity making it especially suitable for medical applications where the working temperatures are restricted. Flow rates of various fluids can be measured over a wide range. The fabricated flow sensors were used to measure the flow rate of water in the range μl - ml/min and gas (Helium) in the range 10 - 100ml/min.

  6. The in situ permeable flow sensor: A device for measuring groundwater flow velocity

    SciTech Connect

    Ballard, S.; Barker, G.T.; Nichols, R.L.

    1994-03-01

    A new technology called the In Situ Permeable Flow Sensor has been developed at Sandia National Laboratories. These sensors use a thermal perturbation technique to directly measure the direction and magnitude of the full three dimensional groundwater flow velocity vector in unconsolidated, saturated, porous media. The velocity measured is an average value characteristic of an approximately 1 cubic meter volume of the subsurface. During a test at the Savannah River Site in South Carolina, two flow sensors were deployed in a confined aquifer in close proximity to a well which was screened over the entire vertical extent of the aquifer and the well was pumped at four different pumping rates. In this situation horizontal flow which is radially directed toward the pumping well is expected. The flow sensors measured horizontal flow which was directed toward the pumping well, within the uncertainty in the measurements. The observed magnitude of the horizontal component of the flow velocity increased linearly with pumping rate, as predicted by theoretical considerations. The measured horizontal component of the flow velocity differed from the predicted flow velocity, which was calculated with the assumptions that the hydraulic properties of the aquifer were radially homogeneous and isotropic, by less than a factor of two. Drawdown data obtained from other wells near the pumping well during the pump test indicate that the hydraulic properties of the aquifer are probably not radially homogeneous but the effect of the inhomogeneity on the flow velocity field around the pumping well was not modeled because the degree and distribution of the inhomogeneity are unknown. Grain size analysis of core samples from wells in the area were used to estimate the vertical distribution of hydraulic conductivity.

  7. Noninvasive measurement of cerebrospinal fluid flow using an ultrasonic transit time flow sensor: a preliminary study.

    PubMed

    Pennell, Thomas; Yi, Juneyoung L; Kaufman, Bruce A; Krishnamurthy, Satish

    2016-03-01

    OBJECT Mechanical failure-which is the primary cause of CSF shunt malfunction-is not readily diagnosed, and the specific reasons for mechanical failure are not easily discerned. Prior attempts to measure CSF flow noninvasively have lacked the ability to either quantitatively or qualitatively obtain data. To address these needs, this preliminary study evaluates an ultrasonic transit time flow sensor in pediatric and adult patients with external ventricular drains (EVDs). One goal was to confirm the stated accuracy of the sensor in a clinical setting. A second goal was to observe the sensor's capability to record real-time continuous CSF flow. The final goal was to observe recordings during instances of flow blockage or lack of flow in order to determine the sensor's ability to identify these changes. METHODS A total of 5 pediatric and 11 adult patients who had received EVDs for the treatment of hydrocephalus were studied in a hospital setting. The primary EVD was connected to a secondary study EVD that contained a fluid-filled pressure transducer and an in-line transit time flow sensor. Comparisons were made between the weight of the drainage bag and the flow measured via the sensor in order to confirm its accuracy. Data from the pressure transducer and the flow sensor were recorded continuously at 100 Hz for a period of 24 hours by a data acquisition system, while the hourly CSF flow into the drip chamber was recorded manually. Changes in the patient's neurological status and their time points were noted. RESULTS The flow sensor demonstrated a proven accuracy of ± 15% or ± 2 ml/hr. The flow sensor allowed real-time continuous flow waveform data recordings. Dynamic analysis of CSF flow waveforms allowed the calculation of the pressure-volume index. Lastly, the sensor was able to diagnose a blocked catheter and distinguish between the blockage and lack of flow. CONCLUSIONS The Transonic flow sensor accurately measures CSF output within ± 15% or ± 2 ml

  8. Characterization of fracture permeability with high-resolution vertical flow measurements during borehole pumping.

    USGS Publications Warehouse

    Paillet, Frederick L.; Hess, A.E.; Cheng, C.H.; Hardin, E.

    1987-01-01

    The distribution of fracture permeability in granitic rocks was investigated by measuring the distribution of vertical flow in boreholes during periods of steady pumping. Pumping tests were conducted at two sites chosen to provide examples of moderately fractured rocks near Mirror Lake, New Hampshire and intensely fractured rocks near Oracle, Arizona. A sensitive heat-pulse flowmeter was used for accurate measurements of vertical flow as low as 0.2 liter per minute. Results indicate zones of fracture permeability in crystalline rocks are composed of irregular conduits that cannot be approximated by planar fractures of uniform aperture, and that the orientation of permeability zones may be unrelated to the orientation of individual fractures within those zones.-Authors

  9. Precision electron flow measurements in a disk transmission line.

    SciTech Connect

    Clark, Waylon T.; Pelock, Michael D.; Martin, Jeremy Paul; Jackson, Daniel Peter Jr.; Savage, Mark Edward; Stoltzfus, Brian Scott; Mendel, Clifford Will, Jr.; Pointon, Timothy David

    2008-01-01

    An analytic model for electron flow in a system driving a fixed inductive load is described and evaluated with particle in cell simulations. The simple model allows determining the impedance profile for a magnetically insulated transmission line given the minimum gap desired, and the lumped inductance inside the transition to the minimum gap. The model allows specifying the relative electron flow along the power flow direction, including cases where the fractional electron flow decreases in the power flow direction. The electrons are able to return to the cathode because they gain energy from the temporally rising magnetic field. The simulations were done with small cell size to reduce numerical heating. An experiment to compare electron flow to the simulations was done. The measured electron flow is {approx}33% of the value from the simulations. The discrepancy is assumed to be due to a reversed electric field at the cathode because of the inductive load and falling electron drift velocity in the power flow direction. The simulations constrain the cathode electric field to zero, which gives the highest possible electron flow.

  10. Phase-locked measurements of gas-liquid horizontal flows

    NASA Astrophysics Data System (ADS)

    Zadrazil, Ivan; Matar, Omar; Markides, Christos

    2014-11-01

    A flow of gas and liquid in a horizontal pipe can be described in terms of various flow regimes, e.g. wavy stratified, annular or slug flow. These flow regimes appear at characteristic gas and liquid Reynolds numbers and feature unique wave phenomena. Wavy stratified flow is populated by low amplitude waves whereas annular flow contains high amplitude and long lived waves, so called disturbance waves, that play a key role in a liquid entrainment into the gas phase (droplets). In a slug flow regime, liquid-continuous regions travel at high speeds through a pipe separated by regions of stratified flow. We use a refractive index matched dynamic shadowgraphy technique using a high-speed camera mounted on a moving robotic linear rail to track the formation and development of features characteristic for the aforementioned flow regimes. We show that the wave dynamics become progressively more complex with increasing liquid and gas Reynolds numbers. Based on the shadowgraphy measurements we present, over a range of conditions: (i) phenomenological observations of the formation, and (ii) statistical data on the downstream velocity distribution of different classes of waves. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  11. Measuring Surface Tension of a Flowing Soap Film

    NASA Astrophysics Data System (ADS)

    Sane, Aakash; Kim, Ildoo; Mandre, Shreyas

    2016-11-01

    It is well known that surface tension is sensitive to the presence of surfactants and many conventional methods exist to measure it. These techniques measure surface tension either by intruding into the system or by changing its geometry. Use of conventional methods in the case of a flowing soap film is not feasible because intruding the soap film changes surface tension due to Marangoni effect. We present a technique in which we measure the surface tension in situ of a flowing soap film without intruding into the film. A flowing soap film is created by letting soap solution drip between two wires. The interaction of the soap film with the wires causes the wires to deflect which can be measured. Surface tension is calculated using a relation between curvature of the wires and the surface tension. Our measurements indicate that the surface tension of the flowing soap film for our setup is around 0.05 N/m. The nature of this technique makes it favorable for measuring surface tension of flowing soap films whose properties change on intrusion.

  12. Two parametric flow measurement in gas-liquid two-phase flow

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Chen, C.; Xu, Y.; Zhao, Z.

    The importance and current development of two parametric measurement during two-phase flow are briefly reviewed in this paper. Gas-liquid two-phase two parametric metering experiments were conducted by using an oval gear meter and a sharp edged orifice mounted in series in a horizontal pipe. Compressed air and water were used as gas and liquid phases respectively. The correlations, which can be used to predict the total flow rate and volumetric quality of two-phase flow or volumetric flow rate of each phase, have also been proposed in this paper. Comparison of the calculated values of flow rate of each phase from the correlations with the test data showed that the root mean square fractional deviation for gas flow rate is 2.9 percent and for liquid flow rate 4.4 percent. The method proposed in this paper can be used to measure the gas and liquid flow rate in two-phase flow region without having to separate the phases.

  13. A New Differential Pressure Flow Meter for Measurement of Human Breath Flow: Simulation and Experimental Investigation.

    PubMed

    Bridgeman, Devon; Tsow, Francis; Xian, Xiaojun; Forzani, Erica

    2016-03-01

    The development and performance characterization of a new differential pressure-based flow meter for human breath measurements is presented in this article. The device, called a "Confined Pitot Tube," is comprised of a pipe with an elliptically shaped expansion cavity located in the pipe center, and an elliptical disk inside the expansion cavity. The elliptical disk, named Pitot Tube, is exchangeable, and has different diameters, which are smaller than the diameter of the elliptical cavity. The gap between the disk and the cavity allows the flow of human breath to pass through. The disk causes an obstruction in the flow inside the pipe, but the elliptical cavity provides an expansion for the flow to circulate around the disk, decreasing the overall flow resistance. We characterize the new sensor flow experimentally and theoretically, using Comsol Multiphysics(®) software with laminar and turbulent models. We also validate the sensor, using inhalation and exhalation tests and a reference method.

  14. Polymer-based micro flow sensor for dynamical flow measurements in hydraulic systems

    NASA Astrophysics Data System (ADS)

    Ahrens, R.; Festa, M.

    2010-06-01

    In this paper we present a micro flow sensor from a polymer for dynamical flow measurements in hydraulic systems. The flow sensor is based on the thermal anemometric principle and consists of two micro-structured housing shells from polysulfone (PSU) which form a small fluidic channel with a cross-section of 580 µm × 400 µm. In between there is a thin polyimide membrane supporting three gold track structures forming an electrical heater and two resistive thermometers which allows the detection of the flow direction, too. The complete sensor is inserted into the hydraulic system, but only a small bypass flow is directed through the fluidic channel by means of a special splitting system. Due to its small heat capacity, the sensor is suitable to detect flow pulsations up to about 1200 Hz which allows the sensor to be used for the condition monitoring or preventive maintenance of hydraulic systems.

  15. Field measurement of basal forces generated by erosive debris flows

    USGS Publications Warehouse

    McCoy, S.W.; Tucker, G.E.; Kean, J.W.; Coe, J.A.

    2013-01-01

    It has been proposed that debris flows cut bedrock valleys in steeplands worldwide, but field measurements needed to constrain mechanistic models of this process remain sparse due to the difficulty of instrumenting natural flows. Here we present and analyze measurements made using an automated sensor network, erosion bolts, and a 15.24 cm by 15.24 cm force plate installed in the bedrock channel floor of a steep catchment. These measurements allow us to quantify the distribution of basal forces from natural debris‒flow events that incised bedrock. Over the 4 year monitoring period, 11 debris‒flow events scoured the bedrock channel floor. No clear water flows were observed. Measurements of erosion bolts at the beginning and end of the study indicated that the bedrock channel floor was lowered by 36 to 64 mm. The basal force during these erosive debris‒flow events had a large‒magnitude (up to 21 kN, which was approximately 50 times larger than the concurrent time‒averaged mean force), high‒frequency (greater than 1 Hz) fluctuating component. We interpret these fluctuations as flow particles impacting the bed. The resulting variability in force magnitude increased linearly with the time‒averaged mean basal force. Probability density functions of basal normal forces were consistent with a generalized Pareto distribution, rather than the exponential distribution that is commonly found in experimental and simulated monodispersed granular flows and which has a lower probability of large forces. When the bed sediment thickness covering the force plate was greater than ~ 20 times the median bed sediment grain size, no significant fluctuations about the time‒averaged mean force were measured, indicating that a thin layer of sediment (~ 5 cm in the monitored cases) can effectively shield the subjacent bed from erosive impacts. Coarse‒grained granular surges and water‒rich, intersurge flow had very similar basal force distributions despite

  16. An Innovative Flow-Measuring Device: Thermocouple Boundary Layer Rake

    NASA Technical Reports Server (NTRS)

    Hwang, Danny P.; Fralick, Gustave C.; Martin, Lisa C.; Wrbanek, John D.; Blaha, Charles A.

    2001-01-01

    An innovative flow-measuring device, a thermocouple boundary layer rake, was developed. The sensor detects the flow by using a thin-film thermocouple (TC) array to measure the temperature difference across a heater strip. The heater and TC arrays are microfabricated on a constant-thickness quartz strut with low heat conductivity. The device can measure the velocity profile well into the boundary layer, about 65 gm from the surface, which is almost four times closer to the surface than has been possible with the previously used total pressure tube.

  17. Measuring fluid flow and heat output in seafloor hydrothermal environments

    NASA Astrophysics Data System (ADS)

    Germanovich, Leonid N.; Hurt, Robert S.; Smith, Joshua E.; Genc, Gence; Lowell, Robert P.

    2015-12-01

    We review techniques for measuring fluid flow and advective heat output from seafloor hydrothermal systems and describe new anemometer and turbine flowmeter devices we have designed, built, calibrated, and tested. These devices allow measuring fluid velocity at high- and low-temperature focused and diffuse discharge sites at oceanic spreading centers. The devices perform at ocean floor depths and black smoker temperatures and can be used to measure flow rates ranging over 2 orders of magnitude. Flow velocity is determined from the rotation rate of the rotor blades or paddle assembly. These devices have an open bearing design that eliminates clogging by particles or chemical precipitates as the fluid passes by the rotors. The devices are compact and lightweight enough for deployment from either an occupied or remotely operated submersible. The measured flow rates can be used in conjunction with vent temperature or geochemical measurements to obtain heat outputs or geochemical fluxes from both vent chimneys and diffuse flow regions. The devices have been tested on 30 Alvin dives on the Juan de Fuca Ridge and 3 Jason dives on the East Pacific Rise (EPR). We measured an anomalously low entrainment coefficient (0.064) and report 104 new measurements over a wide range of discharge temperatures (5°-363°C), velocities (2-199 cm/s), and depths (1517-2511 m). These include the first advective heat output measurements at the High Rise vent field and the first direct fluid flow measurement at Middle Valley. Our data suggest that black smoker heat output at the Main Endeavour vent field may have declined since 1994 and that after the 2005-2006 eruption, the high-temperature advective flow at the EPR 9°50'N field may have become more channelized, predominately discharging through the Bio 9 structure. We also report 16 measurements on 10 Alvin dives and 2 Jason dives with flow meters that predate devices described in this work and were used in the process of their development

  18. A Structured-Grid Quality Measure for Simulated Hypersonic Flows

    NASA Technical Reports Server (NTRS)

    Alter, Stephen J.

    2004-01-01

    A structured-grid quality measure is proposed, combining three traditional measurements: intersection angles, stretching, and curvature. Quality assesses whether the grid generated provides the best possible tradeoffs in grid stretching and skewness that enable accurate flow predictions, whereas the grid density is assumed to be a constraint imposed by the available computational resources and the desired resolution of the flow field. The usefulness of this quality measure is assessed by comparing heat transfer predictions from grid convergence studies for grids of varying quality in the range of [0.6-0.8] on an 8'half-angle sphere-cone, at laminar, perfect gas, Mach 10 wind tunnel conditions.

  19. Constraints on Lava Flow Emplacement Derived From Precision Topographic Measurements

    NASA Astrophysics Data System (ADS)

    Zimbelman, J. R.; Bjonnes, E. E.

    2005-12-01

    Precision topography obtained with a Differential Global Positioning System (DGPS) was used to derive constraints on the physical properties of two lava flows on the Big Island of Hawaii. We used a Trimble 4800 DGPS to collect positional information across the lava flows with < 2 cm horizontal and < 4 cm vertical precision (but field tests show that points are usually repeatable to < 1 cm both horizontally and vertically). The DGPS data were overlaid on georeferenced aerial and satellite imaging data, allowing us to correlate the measured topographic points to field notes and photographs, as well as to the local setting evident in the vertical images. We combined field and imaging data for the eastern lobe of the 1907 basalt flow from the southwestern rift zone of Mauna Loa volcano, east of the Ocean View Estates subdivision, and for portions of a grass-covered Pleistocene benmoreite flow near Mana on the western flank of Mauna Kea volcano. Measured physical dimensions of the Hawaiian lava flows obtained from the DGPS data were then used to calculate the yield strength, average effusion rate, and effective viscosity of the lavas using published relationships derived from diverse theories of fluid flow. Yield strengths obtained from three different expressions ranged from 5800 to 56000 Pa for the Mauna Loa basalt flow and from 13000 to 28000 Pa for the Mauna Kea benmoreite flow. Total flow length could not be determined for the Mauna Kea flow, but the entire surface portion of the 1907 flow is well exposed; this allowed us to calculate an average effusion rate of 29 m/s and effective viscosities ranging from 17000 to 280000 Pa-s for this flow, broadly consistent with values published for the 1984 basalt flow from the eastern rift zone of Mauna Loa. These results improve our confidence in being able to derive similar constraints on the likely emplacement conditions of lava flows on other planets, such as the enormous lava flows commonly found on the martian, venusian

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

    PubMed

    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.

  1. A technique for measuring hypersonic flow velocity profiles

    NASA Technical Reports Server (NTRS)

    Gartrell, L. R.

    1973-01-01

    A technique for measuring hypersonic flow velocity profiles is described. This technique utilizes an arc-discharge-electron-beam system to produce a luminous disturbance in the flow. The time of flight of this disturbance was measured. Experimental tests were conducted in the Langley pilot model expansion tube. The measured velocities were of the order of 6000 m/sec over a free-stream density range from 0.000196 to 0.00186 kg/cu m. The fractional error in the velocity measurements was less than 5 percent. Long arc discharge columns (0.356 m) were generated under hypersonic flow conditions in the expansion-tube modified to operate as an expansion tunnel.

  2. A flight experiment to measure rarefied-flow aerodynamics

    NASA Technical Reports Server (NTRS)

    Blanchard, Robert C.

    1990-01-01

    A flight experiment to measure rarefied-flow aerodynamics of a blunt lifting body is being developed by NASA. This experiment, called the Rarefied-Flow Aerodynamic Measurement Experiment (RAME), is part of the Aeroassist Flight Experiment (AFE) mission, which is a Pathfinder design tool for aeroassisted orbital transfer vehicles. The RAME will use flight measurements from accelerometers, rate gyros, and pressure transducers, combined with knowledge of AFE in-flight mass properties and trajectory, to infer aerodynamic forces and moments in the rarefied-flow environment, including transition into the hypersonic continuum regime. Preflight estimates of the aerodynamic measurements are based upon environment models, existing computer simulations, and ground test results. Planned maneuvers at several altitudes will provide a first-time opportunity to examine gas-surface accommondation effects on aerodynamic coefficients in an environment of changing atmospheric composition. A description is given of the RAME equipment design.

  3. Measurements and simulation of the flow around a poppet valve

    NASA Astrophysics Data System (ADS)

    Lilek, Z.; Nadarajah, S.; Peric, M.; Tindal, M. J.; Yianneskis, M.

    The flow through an axisymmetric inlet port was investigated experimentally and numerically. Laser-Doppler anemometry was used to measure the three ensemble-averaged mean and rms velocity components for two valve lifts, 6 and 10 mm. Numerical calculations of the flows were carried out using a finite volume multigrid method and a standard k-epsilon turbulence model. Comparison of the predictions with the experimental results shows good agreement for the mean velocities for the 10 mm lift case. However, for the 6 mm liftcase the predicted flow differs substantially from the experimental results. This indicates the extreme sensitivity of the flow to the valve lift and the need for more sophisticated turbulence modeling when predicting such flows.

  4. Simultaneous measurements and flow visualization in a plane mixing layer

    NASA Astrophysics Data System (ADS)

    Sherikar, S. V.; Chevray, R.

    Wind tunnel experiments performed to determine the flow characteristics of a plane mixing layer are described. Two parallel streams of air moving at different velocities were separated by a splitter plate prior to their mixing in the test section. Gaseous NH3 and gaseous HCI were introduced near the splitter plate to produce an ammonium chloride aerosol which made flow visualization possible. Flow visualization records (movies) and velocity measurements, using laser-doppler-velocimeters tracking silicone oil particles in the flow, were made simultaneously and synchronized using a chopped beam of a He-Ne laser which left a signature on the move film and provided a signal for flow rate data acquisition. Analysis of these synchronized data verified the existence of large, essentially two-dimensional coherent structures in the plane mixing layer.

  5. Direct measurement of the flow field around swimming microorganisms

    NASA Astrophysics Data System (ADS)

    Polin, Marco; Drescher, Knut; Goldstein, Raymond E.; Michel, Nicolas; Tuval, Idan

    2010-11-01

    Swimming microorganisms create flows that influence their mutual interactions and modify the rheology of their suspensions. While extensively studied theoretically, these flows have not been measured in detail around any freely-swimming microorganism. We report such measurements for the microphytes Volvox carteri and Chlamydomonas reinhardtii. The minute (˜0.3%) density excess of V. carteri over water leads to a strongly dominant Stokeslet contribution, with the widely-assumed stresslet flow only a correction to the subleading source dipole term. This implies that suspensions of V. carteri have features similar to suspensions of sedimenting particles. The flow in the region around C. reinhardtii where significant hydrodynamic interaction is likely to occur differs qualitatively from a "puller" stresslet, and can be described by a simple three-Stokeslet model.

  6. Direct Measurement of the Flow Field around Swimming Microorganisms

    NASA Astrophysics Data System (ADS)

    Drescher, Knut; Goldstein, Raymond E.; Michel, Nicolas; Polin, Marco; Tuval, Idan

    2010-10-01

    Swimming microorganisms create flows that influence their mutual interactions and modify the rheology of their suspensions. While extensively studied theoretically, these flows have not been measured in detail around any freely-swimming microorganism. We report such measurements for the microphytes Volvox carteri and Chlamydomonas reinhardtii. The minute (˜0.3%) density excess of V. carteri over water leads to a strongly dominant Stokeslet contribution, with the widely-assumed stresslet flow only a correction to the subleading source dipole term. This implies that suspensions of V. carteri have features similar to suspensions of sedimenting particles. The flow in the region around C. reinhardtii where significant hydrodynamic interaction is likely to occur differs qualitatively from a puller stresslet, and can be described by a simple three-Stokeslet model.

  7. Improved technique for blood flow velocity measurement using Doppler effect

    NASA Astrophysics Data System (ADS)

    Valadares Oliveira, Eduardo J.; Nantes Button, Vera L. d. S.; Maia, Joaquim M.; Costa, Eduardo T.

    2002-04-01

    The Doppler velocimeter developed allows to determine the angle between the ultrasonic beam and the velocity vector of the flow, and to calculate the precise blood flow in a vessel. Four piezoelectric transducers constitute the Doppler velocimeter. Three of these transducers are positioned to form an equilateral triangle (base of a pyramid). When these transducers move simultaneously, backward or forward from the initial position, the emitted ultrasonic beams focalize on a position (peak of the pyramid) closer or farther from the transducers faces, according to the depth of the vessel where we intend to measure de flow. The angle between the transducers allows adjusting the height of this pyramid and the position of the focus (where the three beams meet). A forth transducer is used to determine the diameter of the vessel and monitor the position of the Doppler velocimeter relative to the vessel. Simulation results showed that with this technique is possible to accomplish precise measurement of blood flow.

  8. Bubbly flow velocity measurements near a heated cylindrical conductor

    SciTech Connect

    Canaan, R.E.; Hassan, Y.A. )

    1990-01-01

    The objective of this study is to apply recent advances and improvements in the digital pulsed laser velocimetry (DPLV) technique to the analysis of two-phase bubbly flow about a cylindrical conductor emitting a constant heat flux within a transparent rectangular enclosure. Pulsed laser velocimetry is a rapidly advancing fluid flow visualization technique that determines full-field instantaneous velocity vectors of a quantitative nature such that the flow field remains undisturbed by the measurement. The DPLV method offers several significant advantages over more traditional fluid velocity measurement techniques such as hot wire/film anemometry and laser Doppler anemometry because reliable instantaneous velocity data may be acquired over substantial flow areas in a single experiment.

  9. Device for Measuring Low Flow Speed in a Duct

    NASA Technical Reports Server (NTRS)

    Quinn, Frank; Magee, Kevin

    2009-01-01

    A multiple-throat venturi system has been invented for measuring laminar flow of air or other gas at low speed (1 to 30 cm/s) in a duct while preserving the laminar nature of the flow and keeping the velocity profile across the duct as nearly flat as possible. While means for measuring flows at higher speeds are well established, heretofore, there have been no reliable means for making consistent, accurate measurements in this speed range. In the original application for which this system was invented, the duct leads into the test section of a low-speed wind tunnel wherein uniform, low-speed, laminar flow is required for scientific experiments. The system could also be used to monitor a slow flow of gas in an industrial process like chemical vapor deposition. In the original application, the multiple- throat venturi system is mounted at the inlet end of the duct having a rectangular cross section of 19 by 14 cm, just upstream of an assembly of inlet screens and flow straighteners that help to suppress undesired flow fluctuations (see Figure 1). The basic venturi measurement principle is well established: One measures the difference in pressure between (1) a point just outside the inlet, where the pressure is highest and the kinetic energy lowest; and (2) the narrowest part (the throat) of the venturi passage, where the kinetic energy is highest and the pressure is lowest. Then by use of Bernoulli s equation for the relationship between pressure and kinetic energy, the volumetric flow speed in the duct can be calculated from the pressure difference and the inlet and throat widths. The design of this system represents a compromise among length, pressure recovery, uniformity of flow, and complexity of assembly. Traditionally, venturis are used to measure faster flows in narrower cross sections, with longer upstream and downstream passages to maintain accuracy. The dimensions of the passages of the present venturi system are sized to provide a readily measurable

  10. Prediction of flow profiles in arteries from local measurements.

    NASA Technical Reports Server (NTRS)

    Ling, S. C.; Atabek, H. B.

    1971-01-01

    This paper develops an approximate numerical method for calculating flow profiles in arteries. The theory takes into account the nonlinear terms of the Navier-Stokes equations as well as the large deformations of the arterial wall. The method, assuming axially symmetric flow, determines velocity distribution and wall shear at a given location from the locally measured values of the pressure, pressure gradient, and pressure-radius relation. The computed results agree well with the corresponding experimental data.

  11. Advanced material distribution measurement in multiphase flows: A case study

    SciTech Connect

    George, D.L.; Ceccio, S.L.; O`Hern, T.J.; Shollenberger, K.A.; Torczynski, J.R.

    1998-08-01

    A variety of tomographic techniques that have been applied to multiphase flows are described. The methods discussed include electrical impedance tomography (EIT), magnetic resonance imaging (MRI), positron emission tomography (PET), gamma-densitometry tomography (GDT), radiative particle tracking (RDT), X-ray imaging, and acoustic tomography. Also presented is a case study in which measurements were made with EIT and GDT in two-phase flows. Both solid-liquid and gas-liquid flows were examined. EIT and GDT were applied independently to predict mean and spatially resolved phase volume fractions. The results from the two systems compared well.

  12. Measurement of VOC reactivities using a photochemical flow reactor

    SciTech Connect

    Hurley, M.D.; Chang, T.Y.; Japar, S.M.; Wallington, T.J.

    1998-07-01

    A commercial ambient air monitoring instrument, the Airtrak 2000, has been modified for use as a photochemical flow reactor and used to measure the absolute and incremental reactivity of 18 single test VOCs and the incremental reactivity of six multicomponent VOC mixtures. A flow technique is a useful supplement to traditional static chamber experiments. The static chamber technique involves periodic sampling of an irradiated mixture in a photochemical chamber. Under these conditions, the irradiated mixture is always in transition. Using a flow system, a steady-state condition is established within the flow reactor that is representative, in this case, of the early stages of the smog forming process in the atmosphere. The measurement technique also allows changes in the background chamber reactivity to be monitored and taken into account. The incremental reactivity of 13 of the 18 test compounds measured is compared with previously reported results from a static chamber experiment, and the two data sets are generally in good agreement. The additivity of reactivity was tested by measuring the incremental reactivity of six multicomponent mixtures, the components being compounds measured individually in this study. The measured reactivity of a mixture was compared to that calculated from the sum of the measured reactivity of the mixture`s individual components. The results show that reactivity is additive for the concentration range studied.

  13. Aqueous Flow Measured by Fluorophotometry in the Mouse

    PubMed Central

    Toris, Carol B.; Fan, Shan; Johnson, Thomas V.; Camras, Lucinda J.; Hays, Cassandra L.; Liu, Hong; Ishimoto, Bruce M.

    2016-01-01

    Purpose A fluorophotometer designed to measure aqueous flow in murine eyes was tested with artificial fluorescein chambers and in live mice with different anesthesia regimens, aqueous flow suppressants, and an anterior chamber cannulation method. Methods Two hours following topical fluorescein application, one group of CD-1 mice was anesthetized with ketamine/xylazine, 2,2,2-tribromoethanol, or ketamine alone. Cornea and anterior chamber fluorescein concentrations were measured periodically for 60 to 90 minutes by fluorophotometric scans to calculate aqueous flow. Later, a subgroup of mice underwent aqueous flow measurement by anterior chamber cannulation. A third group was treated with timolol, dorzolamide, and vehicle in a crossover manner 1 hour prior to fluorophotometric scans. Results Aqueous flow with ketamine/xylazine anesthesia (0.09 ± 0.05 μL/min, mean ± SD, n = 24) was slower than with tribromoethanol or ketamine alone (P < 0.001). Timolol reduced aqueous flow from 0.20 ± 0.07 μL/min to 0.07 ± 0.03 μL/min (P = 0.001) under tribromoethanol anesthesia and from 0.14 ± 0.03 μL/min to 0.10 ± 0.02 μL/min (P = 0.004) under ketamine anesthesia but not under ketamine/xylazine anesthesia. Dorzolamide reduced aqueous flow from 0.09 ± 0.03 to 0.06 ± 0.03 μL/min (P = 0.04) under ketamine/xylazine anesthesia. Aqueous flow by anterior chamber cannulation (0.20 ± 0.13 μL/min) was greater (P = 0.05) than by fluorophotometry (0.09 ± 0.07 μL/min). Conclusions A new noninvasive fluorophotometric method detected effects of general anesthesia and known aqueous suppressants on aqueous flow in mice. Aqueous flow measured by fluorophotometry was slower than by cannulation, and was technically easier with less variability. The mouse fluorophotometer is useful for repeated measurements of aqueous flow in the murine eye making crossover and longitudinal studies possible. PMID:27447085

  14. Measurements of flow-induced birefringence in microfluidics

    PubMed Central

    Sun, Chen-li; Huang, Hung-Yen

    2016-01-01

    In this study, we demonstrate the use of a microscopic circular polariscope to measure the flow-induced birefringence in a microfluidic device that represents the kinematics of fluid motion optically. Unlike the commercial birefringence microscope employed in the previous studies, our approach is able to provide direct measurement of retardance, which quantifies the difference in refractive index of the fluid experienced by the ordinary and extraordinary rays, from one single image frame. This capability facilitates unsteady full-field quantitation of flow-induced birefringence in microfluidics that has never been achieved before. At low flow rates, we find that the value of the retardance is independent of the microfluidic design and proportional to the nominal strain rates. This linearity bridges the measurement of birefringence and the deformation rate in the microflow environment, which yields the stress information of the fluid flow. In addition, the μPIV results confirm that both extensional and shear strain rates contribute to the flow-induced birefringence so that the retardance distribution can be used to represent the field of the principal strain rate in a microfluidic device. The outcome of this study proves that our approach provides a non-invasive method that enables an intuitive full-field representation of stress in the instantaneous flow field in a microfluidic device. PMID:26858809

  15. Measurement and Modelling of a Heaving Airfoil Flow

    NASA Astrophysics Data System (ADS)

    Troshin, Victor; Seifert, Avraham

    2016-11-01

    An outline of a low order modelling procedure of a heaving airfoil in still fluid using experimental measurements is provided. Due to its relative simplicity, the proposed procedure is applicable for the analysis of flow fields within complex and unsteady geometries and it is ideal for analysing the data obtained by experimentation. Currently, this procedure is used to model and predict the flow field evolution using small number of low profile load sensors and flow field measurements. The time delay neural networks are used in order to estimate the flow field. The neural networks estimate the amplitudes of the most energetic modes using four sensory inputs. The modes are calculated using proper orthogonal decomposition (POD) of the flow field data obtained experimentally by time-resolved, phase-locked particle imaging velocimetry. In order to permit the use of proper orthogonal decomposition, the measured flow field is mapped onto a stationary domain using volume preserving transformation. The analysis performed by the model showed good estimation quality within the parameter range used in the training procedure. However, the performance deteriorates for cases out of this range. This state indicates that, in order to improve the robustness of the model, both the decomposition and the training data sets must be diverse.

  16. System and method measuring fluid flow in a conduit

    DOEpatents

    Ortiz, M.G.; Kidd, T.G.

    1999-05-18

    A system is described for measuring fluid mass flow in a conduit in which there exists a pressure differential in the fluid between at least two spaced-apart locations in the conduit. The system includes a first pressure transducer disposed in the side of the conduit at a first location for measuring pressure of fluid at that location, a second or more pressure transducers disposed in the side of the conduit at a second location, for making multiple measurements of pressure of fluid in the conduit at that location, and a computer for computing the average pressure of the multiple measurements at the second location and for computing flow rate of fluid in the conduit from the pressure measurement by the first pressure transducer and from the average pressure calculation of the multiple measurements. 3 figs.

  17. System and method measuring fluid flow in a conduit

    DOEpatents

    Ortiz, Marcos German; Kidd, Terrel G.

    1999-01-01

    A system for measuring fluid mass flow in a conduit in which there exists a pressure differential in the fluid between at least two spaced-apart locations in the conduit. The system includes a first pressure transducer disposed in the side of the conduit at a first location for measuring pressure of fluid at that location, a second or more pressure transducers disposed in the side of the conduit at a second location, for making multiple measurements of pressure of fluid in the conduit at that location, and a computer for computing the average pressure of the multiple measurements at the second location and for computing flow rate of fluid in the conduit from the pressure measurement by the first pressure transducer and from the average pressure calculation of the multiple measurements.

  18. Measurement Of Multiphase Flow Water Fraction And Water-cut

    NASA Astrophysics Data System (ADS)

    Xie, Cheng-gang

    2007-06-01

    This paper describes a microwave transmission multiphase flow water-cut meter that measures the amplitude attenuation and phase shift across a pipe diameter at multiple frequencies using cavity-backed antennas. The multiphase flow mixture permittivity and conductivity are derived from a unified microwave transmission model for both water- and oil-continuous flows over a wide water-conductivity range; this is far beyond the capability of microwave-resonance-based sensors currently on the market. The water fraction and water cut are derived from a three-component gas-oil-water mixing model using the mixture permittivity or the mixture conductivity and an independently measured mixture density. Water salinity variations caused, for example, by changing formation water or formation/injection water breakthrough can be detected and corrected using an online water-conductivity tracking technique based on the interpretation of the mixture permittivity and conductivity, simultaneously measured by a single-modality microwave sensor.

  19. Measurements in a large angle oblique jet impingement flow

    NASA Technical Reports Server (NTRS)

    Foss, J. F.

    1974-01-01

    Velocity and surface pressure measurements, in the flow field of an obliquely impinging jet, and their interpretation as regards the governing mechanics and the aerodynamic noise generation characteristics of such a flow are reported. A computer controlled probe positioning mechanism allowed the measurement of the velocity magnitude and direction in the plane parallel to the plate. The mean velocity and Reynolds stress components were recorded. Measures of the terms in the momentum equation reveal the character of the pressure gradients in the neighborhood of the stagnation point. The effects of the stagnation streamline location on the vorticity field and the vortex sound considerations are discussed in relationship to the aerodynamic noise generation effects of this flow.

  20. Superelevation measurements of debris flows in a curved flume construction.

    NASA Astrophysics Data System (ADS)

    Scheidl, Christian; Rickenmann, Dieter; McArdell, Brian W.

    2013-04-01

    A possible approach to estimate maximum flow velocities is based on the vortex equation by using superelevation marks. Superelevation can be observed in bending channels, where the flow-height of the inner-curvature is lower than the flow-height of the outer-curvature, caused by the centrifugal acceleration of the flow. The objective of this work is to analyze the influence of channel geometry (bend radius and slope) and material properties on the vortex equation when applying to debris flows. In particular, the project aims to compare observed flow velocities from physical modeling in flume experiments with observations from debris-flow field sites. In a first step experimental investigations are done at the laboratory of the Swiss Federal Institute WSL, Birmensdorf. The flume consists of a flexible plastic half-pipe and is mounted on a wooden plane construction. Two different bend radii (1.0 m and 3.0 m) with a bend angle of 60° are implemented. The total length of the flume, of about 8 m, is further covered with 40 grit silicon carbide sandpaper reflecting a constant basal friction layer. To apply for the complexity of a debris-flow process, four different material mixtures based on four different grain size distributions, were defined. Superelevation is measured by laser devices mounted at two cross sections differing in their bend radii. The maximum flow velocity is measured by high-speed cameras. Additionally, a balance is placed to measure weight over time at the outflow. 80 experiments have been conducted, based on the maximum channel slope of 36 %. Another 38 experiments were performed with a channel slope of 27 %. In total, we accomplished 61 experiments for the 3.0 m bend radius and 57 experiments for the 1.0 m bend radius. Front velocities of the debris-flow experiments range between 0.4 m/s and 2.4 m/s. First analyses show plausible results when comparing observed and back calculated flow velocities. Beside the experiments, a second step of this

  1. Flow Disturbance Measurements in the National Transonic Facility

    NASA Technical Reports Server (NTRS)

    King, Rudolph A.; Andino, Marlyn Y.; Melton, Latunia; Eppink, Jenna; Kegerise, Michael A.

    2013-01-01

    Recent flow measurements have been acquired in the National Transonic Facility to assess the test-section unsteady flow environment. The primary purpose of the test is to determine the feasibility of the facility to conduct laminar-flow-control testing and boundary-layer transition-sensitive testing at flight-relevant operating conditions throughout the transonic Mach number range. The facility can operate in two modes, warm and cryogenic test conditions for testing full and semispan-scaled models. Data were acquired for Mach and unit Reynolds numbers ranging from 0.2 less than or equal to M less than or equal to 0.95 and 3.3 × 10(exp 6) less than Re/m less than 220×10(exp 6) collectively at air and cryogenic conditions. Measurements were made in the test section using a survey rake that was populated with 19 probes. Roll polar data at selected conditions were obtained to look at the uniformity of the flow disturbance field in the test section. Data acquired included mean total temperatures, mean and fluctuating static/total pressures, and mean and fluctuating hot-wire measurements. This paper focuses primarily on the unsteady pressure and hot-wire results. Based on the current measurements and previous data, an assessment was made that the facility may be a suitable facility for ground-based demonstrations of laminar-flow technologies at flight-relevant conditions in the cryogenic mode.

  2. Measurement of Two-Phase Flow Characteristics Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Keshock, E. G.; Lin, C. S.; Edwards, L. G.; Knapp, J.; Harrison, M. E.; Xhang, X.

    1999-01-01

    This paper describes the technical approach and initial results of a test program for studying two-phase annular flow under the simulated microgravity conditions of KC-135 aircraft flights. A helical coil flow channel orientation was utilized in order to circumvent the restrictions normally associated with drop tower or aircraft flight tests with respect to two-phase flow, namely spatial restrictions preventing channel lengths of sufficient size to accurately measure pressure drops. Additionally, the helical coil geometry is of interest in itself, considering that operating in a microgravity environment vastly simplifies the two-phase flows occurring in coiled flow channels under 1-g conditions for virtually any orientation. Pressure drop measurements were made across four stainless steel coil test sections, having a range of inside tube diameters (0.95 to 1.9 cm), coil diameters (25 - 50 cm), and length-to-diameter ratios (380 - 720). High-speed video photographic flow observations were made in the transparent straight sections immediately preceding and following the coil test sections. A transparent coil of tygon tubing of 1.9 cm inside diameter was also used to obtain flow visualization information within the coil itself. Initial test data has been obtained from one set of KC-135 flight tests, along with benchmark ground tests. Preliminary results appear to indicate that accurate pressure drop data is obtainable using a helical coil geometry that may be related to straight channel flow behavior. Also, video photographic results appear to indicate that the observed slug-annular flow regime transitions agree quite reasonably with the Dukler microgravity map.

  3. A Moderated Nonlinear Factor Model for the Development of Commensurate Measures in Integrative Data Analysis

    PubMed Central

    Curran, Patrick J.; McGinley, James S.; Bauer, Daniel J.; Hussong, Andrea M.; Burns, Alison; Chassin, Laurie; Sher, Kenneth; Zucker, Robert

    2015-01-01

    Integrative data analysis (IDA) is a methodological framework that allows for the fitting of models to data that have been pooled across two or more independent sources. IDA offers many potential advantages including increased statistical power, greater subject heterogeneity, higher observed frequencies of low base-rate behaviors, and longer developmental periods of study. However, a core challenge is the estimation of valid and reliable psychometric scores that are based on potentially different items with different response options drawn from different studies. In Bauer and Hussong (2009) we proposed a method for obtaining scores within an IDA called moderated nonlinear factor analysis (MNLFA). Here we move significantly beyond this work in the development of a general framework for estimating MNLFA models and obtaining scale scores across a variety of settings. We propose a five step procedure and demonstrate this approach using data drawn from n=1972 individuals ranging in age from 11 to 34 years pooled across three independent studies to examine the factor structure of 17 binary items assessing depressive symptomatology. We offer substantive conclusions about the factor structure of depression, use this structure to compute individual-specific scale scores, and make recommendations for the use of these methods in practice. PMID:25960575

  4. Wear Testing of Moderate Activities of Daily Living Using In Vivo Measured Knee Joint Loading

    PubMed Central

    Reinders, Jörn; Sonntag, Robert; Vot, Leo; Gibney, Christian; Nowack, Moritz; Kretzer, Jan Philippe

    2015-01-01

    Resumption of daily living activities is a basic expectation for patients provided with total knee replacements. However, there is a lack of knowledge regarding the impact of different activities on the wear performance. In this study the wear performance under application of different daily activities has been analyzed. In vivo load data for walking, walking downstairs/upstairs, sitting down/standing up, and cycling (50 W & 120 W) has been standardized for wear testing. Wear testing of each activity was carried out on a knee wear simulator. Additionally, ISO walking was tested for reasons of comparison. Wear was assessed gravimetrically and wear particles were analyzed. In vivo walking produced the highest overall wear rates, which were determined to be three times higher than ISO walking. Moderate wear rates were determined for walking upstairs and downstairs. Low wear rates were determined for standing up/sitting down and cycling at power levels of 50 W and 120 W. The largest wear particles were observed for cycling. Walking based on in vivo data has been shown to be the most wear-relevant activity. Highly demanding activities (stair climbing) produced considerably less wear. Taking into account the expected number of loads, low-impact activities like cycling may have a greater impact on articular wear than highly demanding activities. PMID:25811996

  5. Regional measurements of blood flow in experimental RG-2 rat gliomas

    SciTech Connect

    Groothuis, D.R.; Pasternak, J.F.; Fischer, J.M.; Blasberg, R.G.; Bigner, D.D.; Vick, N.A.

    1983-07-01

    Regional measurements of blood flow (F) were performed in transplanted intracerebral RG-2 rat gliomas using (14C)iodoantipyrine, Kety-Schmidt blood flow equations, and quantitative autoradiography. Twenty-nine intracranial tumors in ten rats were analyzed by location; 18 intraparenchymal, seven meningeal, two third-ventricular, and two fourth-ventricular tumors were studied. For all tumors, averaged mean F was 91 +/- 33 (S.D.) ml/hg/min. In all but one tumor, mean F was intermediate between normal cortex and corpus callosum values. There was moderate regional variation: averaged mean F was lower in tumor center (78 +/- 47 ml/hg/min) than in tumor periphery (93 +/- 30 ml/hg/min). Within individual tumors, F showed moderate variation which correlated to some extent with histological features; a regional F of less than 10 ml/hg/min was observed in only one tumor within an area of necrosis. F in regions of brain immediately surrounding the tumor was higher than in tumor periphery. Blood flow to RG-2 tumors seems unlikely to limit drug delivery any more than to normal brain, and the consistent levels from tumor to tumor and within individual tumors make the RG-2 model an excellent one with which to study drug delivery in experimental brain tumors.

  6. Sensors for Using Times of Flight to Measure Flow Velocities

    NASA Technical Reports Server (NTRS)

    Fralick, Gutave; Wrbanek, John D.; Hwang, Danny; Turso, James

    2006-01-01

    Thin-film sensors for measuring flow velocities in terms of times of flight are undergoing development. These sensors are very small and can be mounted flush with surfaces of airfoils, ducts, and other objects along which one might need to measure flows. Alternatively or in addition, these sensors can be mounted on small struts protruding from such surfaces for acquiring velocity measurements at various distances from the surfaces for the purpose of obtaining boundary-layer flow-velocity profiles. These sensors are related to, but not the same as, hot-wire anemometers. Each sensor includes a thin-film, electrically conductive loop, along which an electric current is made to flow to heat the loop to a temperature above that of the surrounding fluid. Instantaneous voltage fluctuations in segments of the loop are measured by means of electrical taps placed at intervals along the loop. These voltage fluctuations are caused by local fluctuations in electrical resistance that are, in turn, caused by local temperature fluctuations that are, in turn, caused by fluctuations in flow-induced cooling and, hence, in flow velocity. The differential voltage as a function of time, measured at each pair of taps, is subjected to cross-correlation processing with the corresponding quantities measured at other pairs of taps at different locations on the loop. The cross-correlations yield the times taken by elements of fluid to travel between the pairs of taps. Then the component of velocity along the line between any two pairs of taps is calculated simply as the distance between the pairs of taps divided by the travel time. Unlike in the case of hot-wire anemometers, there is no need to obtain calibration data on voltage fluctuations versus velocity fluctuations because, at least in principle, the correlation times are independent of the calibration data.

  7. Doppler Global Velocimetry Measurements for Supersonic Flow Fields

    NASA Technical Reports Server (NTRS)

    Meyers, James F.

    2005-01-01

    The application of Doppler Global Velocimetry (DGV) to high-speed flows has its origins in the original development of the technology by Komine et al (1991). Komine used a small shop-air driven nozzle to generate a 200 m/s flow. This flow velocity was chosen since it produced a fairly large Doppler shift in the scattered light, resulting in a significant transmission loss as the light passed through the Iodine vapor. This proof-of-concept investigation showed that the technology was capable of measuring flow velocity within a measurement plane defined by a single-frequency laser light sheet. The effort also proved that velocity measurements could be made without resolving individual seed particles as required by other techniques such as Fringe- Type Laser Velocimetry and Particle Image Velocimetry. The promise of making planar velocity measurements with the possibility of using 0.1-micron condensation particles for seeding, Dibble et al (1989), resulted in the investigation of supersonic jet flow fields, Elliott et al (1993) and Smith and Northam (1995) - Mach 2.0 and 1.9 respectively. Meyers (1993) conducted a wind tunnel investigation above an inclined flat plate at Mach 2.5 and above a delta wing at Mach 2.8 and 4.6. Although these measurements were crude from an accuracy viewpoint, they did prove that the technology could be used to study supersonic flows using condensation as the scattering medium. Since then several research groups have studied the technology and developed solutions and methodologies to overcome most of the measurement accuracy limitations:

  8. Measurements of Turbulent Flow Field in Separate Flow Nozzles with Enhanced Mixing Devices - Test Report

    NASA Technical Reports Server (NTRS)

    Bridges, James

    2002-01-01

    As part of the Advanced Subsonic Technology Program, a series of experiments was conducted at NASA Glenn Research Center on the effect of mixing enhancement devices on the aeroacoustic performance of separate flow nozzles. Initial acoustic evaluations of the devices showed that they reduced jet noise significantly, while creating very little thrust loss. The explanation for the improvement required that turbulence measurements, namely single point mean and RMS statistics and two-point spatial correlations, be made to determine the change in the turbulence caused by the mixing enhancement devices that lead to the noise reduction. These measurements were made in the summer of 2000 in a test program called Separate Nozzle Flow Test 2000 (SFNT2K) supported by the Aeropropulsion Research Program at NASA Glenn Research Center. Given the hot high-speed flows representative of a contemporary bypass ratio 5 turbofan engine, unsteady flow field measurements required the use of an optical measurement method. To achieve the spatial correlations, the Particle Image Velocimetry technique was employed, acquiring high-density velocity maps of the flows from which the required statistics could be derived. This was the first successful use of this technique for such flows, and shows the utility of this technique for future experimental programs. The extensive statistics obtained were likewise unique and give great insight into the turbulence which produces noise and how the turbulence can be modified to reduce jet noise.

  9. Spatial and Numerical Predictors of Measurement Performance: The Moderating Effects of Community Income and Gender

    ERIC Educational Resources Information Center

    Casey, Beth M.; Dearing, Eric; Vasilyeva, Marina; Ganley, Colleen M.; Tine, Michele

    2011-01-01

    Spatial reasoning and numerical predictors of measurement performance were investigated in 4th graders from low-income and affluent communities. Predictors of 2 subtypes of measurement performance (spatial-conceptual and formula based) were assessed while controlling for verbal and spatial working memory. Consistent with prior findings, students…

  10. Flow cytometric measurement of total DNA and incorporated halodeoxyuridine

    DOEpatents

    Dolbeare, Frank A.; Gray, Joe W.

    1986-01-01

    A method for the simultaneous flow cytometric measurement of the total DNA content and the level of DNA synthesis in normal and malignant cells is disclosed. The sensitivity of the method allows a study of cell cycle traverse rates for large scale cell populations as well as single cell measurements. A DNA stain such as propidium iodide is used as the probe for the measurement of total DNA content and a monoclonal antibody reactive with a DNA precursor such as bromodeoxyuridine (BrdU) is used as a probe for the measurement of BrdU uptake by the cells as a measure of DNA synthesis.

  11. A new approach to highly resolved measurements of turbulent flow

    NASA Astrophysics Data System (ADS)

    Puczylowski, J.; Hölling, A.; Peinke, J.; Bhiladvala, R.; Hölling, M.

    2015-05-01

    In this paper we present the design and principle of a new anemometer, namely the 2d-Laser Cantilever Anemometer (2d-LCA), which has been developed for highly resolved flow speed measurements of two components (2d) under laboratory conditions. We will explain the working principle and demonstrate the sensor’s performance by means of comparison measurements of wake turbulence with a commercial X-wire. In the past we have shown that the 2d-LCA is capable of being applied in liquid and particle-laden domains, but we also believe that other challenging areas of operation such as near-wall flows can become accessible.

  12. Fluidic Control of Nozzle Flow: Some Performance Measurements

    NASA Technical Reports Server (NTRS)

    Federspiel, John; Bangert, Linda; Wing, David; Hawkes, Tim

    1995-01-01

    Results are presented of an experimental program that investigated the use of a secondary air stream to control the amount of flow through a convergent-divergent nozzle. These static tests utilized high pressure, ambient temperature air that was injected at the throat of the nozzle through an annular slot. Multiple injection slot sizes and injection angles were tested. The introduction of secondary flow was made in an opposing direction to the primary flow and the resulting flow field caused the primary stream to react as though the physical throat size had been reduced. The percentage reduction in primary flow rate was generally about twice the injected flow rate. The most effective throttling was achieved by injecting through the smallest slot in an orientation most nearly opposed to the approaching primary flow. Thrust edliciency, as measured by changes in nozzle thrust coefficient, was highest at high nozzle pressure ratios, NPR. The static test results agreed with predictions obtained prior from PABSD, a fully viscous computational fluid dynamics program. Since use of such an injection system on gas turbine engine exhaust nozzles would be primarily at high NPRs, it was concluded that fluidic control holds promise for reducing nozzle weight and complexity on future systems.

  13. PIV measurements and flow characteristics downstream of mangrove root models

    NASA Astrophysics Data System (ADS)

    Kazemi, Amirkhosro; Curet, Oscar

    2016-11-01

    Mangrove forests attracted attentions as a solution to protect coastal areas exposed to sea-level rising, frequent storms, and tsunamis. Mangrove forests found in tide-dominated flow regions are characterized by their massive and complex root systems, which play a prominent role in the structure of tidal flow currents. To understand the role of mangrove roots in flow structure, we modeled mangrove roots with rigid and flexible arrays of cylinders with different spacing between them as well as different configurations. In this work, we investigate the fluid dynamics downstream of the models using a 2-D time-resolved particle image velocimetry (PIV) and flow visualization. We carried out experiments for four different Reynolds number based on cylinder diameters ranges from 2200 to 12000. We present time-averaged and time-resolved flow parameters including velocity distribution, vorticity, streamline, Reynolds shear stress and turbulent kinetic energy. The results show that the flow structure has different vortex shedding downstream of the cylinders due to interactions of shear layers separating from cylinders surface. The spectral analysis of the measured velocity data is also performed to obtain Strouhal number of the unsteady flow in the cylinder wake.

  14. Regional Skin Temperature Response to Moderate Aerobic Exercise Measured by Infrared Thermography

    PubMed Central

    Fernandes, Alex de Andrade; Amorim, Paulo Roberto dos Santos; Brito, Ciro José; Sillero-Quintana, Manuel; Bouzas Marins, João Carlos

    2016-01-01

    Background: Infrared thermography (IRT) does not require contact with the skin, and it is a convenient, reliable and non-invasive technique that can be used for monitoring the skin temperature (TSK). Objectives: The aim of this study was to monitor the variations in the regional TSK during exercise on 28 regions of interest (ROIs) (forehead, face, chest, abdomen, back, lumbar, anterior and posterior neck, and posterior and anterior views of the right and left hands, forearms, upper arms, thighs, and legs) with IRT. Patients and Methods: 12 physically active young males were monitored with IRT during the following three phases: a) 30 minutes before exercise b) while performing one hour of moderate intensity exercise on a treadmill at 60% of the VO2max, and c) 60 minutes after exercise. Results: During pre-exercise, all TSK reached a steady-state (P ≤ 0.05), which ensured adequate thermal stabilisation. At the beginning of exercise, there was a significant reduction in the TSK in most ROIs after 10 minutes of activity, except for the lower limbs (legs and thighs). After one hour of recovery, in the anterior view of the hands and thighs and in the posterior view of the legs, there were significant increases in the TSK compared to pre-exercise. Conclusions: There were significant distinctions in the skin temperature distribution during exercise according to the activity of the area under consideration during exercise, which may be important in the development of physiological models and heat flux analyses for different purposes. PMID:27217931

  15. Flow field measurements in the cell culture unit.

    PubMed

    Walker, Stephen; Wilder, Mike; Dimanlig, Arsenio; Jagger, Justin; Searby, Nancy

    2002-10-01

    The cell culture unit (CCU) is being designed to support cell growth for long-duration life science experiments on the International Space Station (ISS). The CCU is a perfused loop system that provides a fluid environment for controlled cell growth experiments within cell specimen chambers (CSCs), and is intended to accommodate diverse cell specimen types. Many of the functional requirements depend on the fluid flow field within the CSC (e.g., feeding and gas management). A design goal of the CCU is to match, within experimental limits, all environmental conditions, other than the effects of gravity on the cells, whether the hardware is in microgravity ( micro g), normal Earth gravity, or up to 2g on the ISS centrifuge. In order to achieve this goal, two steps are being taken. The first step is to characterize the environmental conditions of current 1g cell biology experiments being performed in laboratories using ground-based hardware. The second step is to ensure that the design of the CCU allows the fluid flow conditions found in 1g to be replicated from microgravity up to 2g. The techniques that are being used to take these steps include flow visualization, particle image velocimetry (PIV), and computational fluid dynamics (CFD). Flow visualization using the injection of dye has been used to gain a global perspective of the characteristics of the CSC flow field. To characterize laboratory cell culture conditions, PIV is being used to determine the flow field parameters of cell suspension cultures grown in Erlenmeyer flasks on orbital shakers. These measured parameters will be compared to PIV measurements in the CSCs to ensure that the flow field that cells encounter in CSCs is within the bounds determined for typical laboratory experiments. Using CFD, a detailed simulation is being developed to predict the flow field within the CSC for a wide variety of flow conditions, including microgravity environments. Results from all these measurements and analyses of the

  16. Flow field measurements in the cell culture unit

    NASA Technical Reports Server (NTRS)

    Walker, Stephen; Wilder, Mike; Dimanlig, Arsenio; Jagger, Justin; Searby, Nancy

    2002-01-01

    The cell culture unit (CCU) is being designed to support cell growth for long-duration life science experiments on the International Space Station (ISS). The CCU is a perfused loop system that provides a fluid environment for controlled cell growth experiments within cell specimen chambers (CSCs), and is intended to accommodate diverse cell specimen types. Many of the functional requirements depend on the fluid flow field within the CSC (e.g., feeding and gas management). A design goal of the CCU is to match, within experimental limits, all environmental conditions, other than the effects of gravity on the cells, whether the hardware is in microgravity ( micro g), normal Earth gravity, or up to 2g on the ISS centrifuge. In order to achieve this goal, two steps are being taken. The first step is to characterize the environmental conditions of current 1g cell biology experiments being performed in laboratories using ground-based hardware. The second step is to ensure that the design of the CCU allows the fluid flow conditions found in 1g to be replicated from microgravity up to 2g. The techniques that are being used to take these steps include flow visualization, particle image velocimetry (PIV), and computational fluid dynamics (CFD). Flow visualization using the injection of dye has been used to gain a global perspective of the characteristics of the CSC flow field. To characterize laboratory cell culture conditions, PIV is being used to determine the flow field parameters of cell suspension cultures grown in Erlenmeyer flasks on orbital shakers. These measured parameters will be compared to PIV measurements in the CSCs to ensure that the flow field that cells encounter in CSCs is within the bounds determined for typical laboratory experiments. Using CFD, a detailed simulation is being developed to predict the flow field within the CSC for a wide variety of flow conditions, including microgravity environments. Results from all these measurements and analyses of the

  17. Heat flow measurements on the southeast coast of Australia

    USGS Publications Warehouse

    Hyndman, R.D.; Jaeger, J.C.; Sass, J.H.

    1969-01-01

    Three boreholes have been drilled for the Australian National University near the southeast coast of New South Wales, Australia. The heat flows found are 1.1, 1.0, and 1.3 ??cal/cm2sec. The errors resulting from the proximity of the sea and a lake, surface temperature change, conductivity structure and water flow have been examined. The radioactive heat production in some of the intrusive rocks of the area have also been measured. The heat flows are much lower than the values of about 2.0 found elsewhere in south eastern Australia. The lower values appear to be part of a distinct heat flow province in eastern Australia. ?? 1969.

  18. Flow measurements in a model ramjet secondary combustion chamber

    SciTech Connect

    Chittilapilly, L.T.; Venkateswaran, S.; Paul, P.J.; Mukunda, H.S. Indian Institute of Science, Bangalore )

    1990-12-01

    Experimental studies were conducted on a typical secondary combustion chamber of a ramjet to understand the influence of various inlet parameters such as primary nozzle configuration, secondary air injection angle, and flow Reynolds numbers on the secondary combustion chamber (SCC) performance. Cold flow studies were made with air as the flow medium for both primary and secondary jets followed by similar studies with hot primary jets. The general flow structure in the SCC obtained from surface oil film technique showed recirculation zones near the head end. The combustor length required for jet mixing was found to be unrelated to recirculation zone length confirmed by selective temperature and total pressure profile measurements. The calculated frictional loss from the momentum balance consideration was found to be small. That significant improvement in mixing can be achieved by a choice of multiple-hole primary nozzle configuration has been demonstrated. 11 refs.

  19. Measurement of anterior and posterior circulation flow contributions to cerebral blood flow. An ultrasound-derived volumetric flow analysis.

    PubMed

    Boyajian, R A; Schwend, R B; Wolfe, M M; Bickerton, R E; Otis, S M

    1995-01-01

    Ultrasound-derived volumetric flow analysis may be useful in answering questions of basic physiological interest in the cerebrovascular circulation. Using this technique, the authors have sought to describe quantitatively the complete concurrent flow relations among all four arteries supplying the brain. The aim of this study of normal subjects was to determine the relative flow contributions of the anterior (internal carotid arteries) and posterior (vertebral arteries) cerebral circulation. Comparisons between the observed and theoretically expected anterior and posterior flow distribution would provide an opportunity to assess traditional rheological conceptions in vivo. Pulsed color Doppler ultrasonography was used to measure mean flow rates in the internal carotid and vertebral arteries in 21 normal adults. The anterior circulation (internal carotid arteries bilaterally) carried 82% of the brain's blood supply and comprised 67% of the total vascular cross-sectional area. These values demonstrate precise concordance between observations in vivo and the theoretically derived (Hagen-Poiseuille) expected flow distribution. These cerebrovascular findings support the traditional conception of macroscopic blood flow. Further studies using ultrasound-derived volumetric analysis of the brain's arterial flow relations may illuminate the vascular pathophysiology underlying aging, cerebral ischemia, and dementias.

  20. Velocity measurement of flow over random soft porous media

    NASA Astrophysics Data System (ADS)

    Selkirk, Isreal; Mirbod, Parisa

    2016-11-01

    The aim of this work is to experimentally examine the flow over random soft porous media in a three-dimensional channel. Various combination of fibrous material and the morphology of the fibers were chosen to achieve void volume fraction (ɛ) ranging from 0.4 to 0.7. Care has been taken to keep the Reynolds number low so that the flow was laminar. The channel height was constant, however the thickness of the fibrous media was varied to achieve different filling fraction. Before starting the tests in the duct with fiber arrays, a series of tests in an empty duct (i.e., without fibers) conducted to validate the experimental measurements. We also discussed the error and uncertainty sources in the experiments and described the techniques to improve their impact. We studied detailed velocity measurements of the flow over fibrous material inside a rectangular duct using a planar particle image velocimetry (PIV) technique. Using these measurements, we determined the values of the slip velocity at the interface between the fibrous media and the flow. It was found that values of the slip velocity normalized by the maximum velocity in the flow depend on solid volume fraction, pore spaces, and fraction of channel filled by the fiber layers.

  1. Low Reynolds number Couette flow facility for drag measurements

    NASA Astrophysics Data System (ADS)

    Johnson, Tyler J.; Lang, Amy W.; Wheelus, Jennifer N.; Westcott, Matthew

    2010-09-01

    For this study a new low Reynolds number Couette facility was constructed to investigate surface drag. In this facility, mineral oil was used as the working fluid to increase the shear stress across the surface of the experimental models. A mounted conveyor inside a tank creates a flow above which an experimental model of a flat plate was suspended. The experimental plate was attached to linear bearings on a slide system that connects to a force gauge used to measure the drag. Within the gap between the model and moving belt a Couette flow with a linear velocity profile was created. Digital particle image velocimetry was used to confirm the velocity profile. The drag measurements agreed within 5% of the theoretically predicted Couette flow value.

  2. Pulsed photoacoustic Doppler flow measurements in blood-mimicking phantoms

    NASA Astrophysics Data System (ADS)

    Brunker, J.; Beard, P.

    2011-03-01

    The feasibility of making spatially resolved measurements of blood flow using pulsed photoacoustic Doppler techniques has been explored. Doppler time shifts were quantified via cross-correlation of pairs of photoacoustic waveforms generated within a blood-simulating phantom using pairs of laser light pulses. The photoacoustic waves were detected using a focussed or planar PZT ultrasound transducer. For each flow measurement, a series of 100 waveform pairs was collected. Previous data processing methods involved rejection of poorly correlated waveform pairs; the modal velocity value and standard deviation were then extracted from the selected distribution of velocity measurements. However, the data selection criteria used in this approach is to some extent arbitrary. A new data analysis protocol, which involves averaging the 100 cross-correlation functions and thus uses all of the measured data, has been designed in order to prevent exclusion of outliers. This more rigorous approach has proved effective for quantifying the linear motion of micron-scale absorbers imprinted on an acetate sheet moving with velocities in the range 0.14 to 1.25 ms-1. Experimental parameters, such as the time separation between the laser pulses and the transducer frequency response, were evaluated in terms of their effect on the accuracy, resolution and range of measurable velocities. The technique was subsequently applied to fluid phantoms flowing at rates less than 5 mms-1 along an optically transparent tube. Preliminary results are described for three different suspensions of phenolic resin microspheres, and also for whole blood. Velocity information was obtained even under non-optimal conditions using a low frequency transducer and a low pulse repetition frequency. The distinguishing advantage of pulsed rather than continuous-wave excitation is that spatially resolved velocity measurements can be made. This offers the prospect of mapping flow within the microcirculation and thus

  3. Time-dependent local density measurements in unsteady flows

    NASA Technical Reports Server (NTRS)

    Mckenzie, R. L.; Monson, D. J.; Exberger, R. J.

    1979-01-01

    A laser-induced fluorescence technique for measuring the relative time-dependent density fluctuations in unsteady or turbulent flows is demonstrated. Using a 1.5-W continuous-wave Kr(+) laser, measurements have been obtained in 0.1-mm diameter by 1-mm-long sampling volumes in a Mach 3 flow of N2 seeded with biacetyl vapor. A signal amplitude resolution of 2% was achieved for a detection frequency bandwidth of 10 kHz. The measurement uncertainty was found to be dominated by noise behaving as photon statistical noise. The practical limits of signal-to-noise ratios have been characterized for a wide range of detection frequency bandwidths that encompasses those of interest in supersonic turbulence measurements.

  4. In vitro hematocrit measurement using spectrally encoded flow cytometry

    PubMed Central

    Zeidan, Adel; Golan, Lior; Yelin, Dvir

    2016-01-01

    Measuring key physiological parameters of small blood samples extracted from patients could be useful for real-time clinical diagnosis at the point of care. An important parameter required from all blood tests is the blood hematocrit, a measure of the fractional volume occupied by the red cells within the blood. In this work, we present a method for in vitro evaluation of hematocrit based on the data acquired using spectrally encoded flow cytometry. Analysis of the reflectance confocal images of blood within a flow chamber resulted in an error as low as 1.7% in the measured hematocrit. The technique could be used as part of an in vitro diagnostic system that measures important blood parameters at the point of care. PMID:27867734

  5. Nonintrusive Temperature and Velocity Measurements in a Hypersonic Nozzle Flow

    NASA Technical Reports Server (NTRS)

    OByrne, S.; Danehy, P. M.; Houwing, A. F. P.

    2002-01-01

    Distributions of nitric oxide vibrational temperature, rotational temperature and velocity have been measured in the hypersonic freestream at the exit of a conical nozzle, using planar laser-induced fluorescence. Particular attention has been devoted to reducing the major sources of systematic error that can affect fluorescence tempera- ture measurements, including beam attenuation, transition saturation effects, laser mode fluctuations and transition choice. Visualization experiments have been performed to improve the uniformity of the nozzle flow. Comparisons of measured quantities with a simple one-dimensional computation are made, showing good agreement between measurements and theory given the uncertainty of the nozzle reservoir conditions and the vibrational relaxation rate.

  6. STORM-SEWER FLOW MEASUREMENT AND RECORDING SYSTEM.

    USGS Publications Warehouse

    Kilpatrick, Frederick A.; Kaehrle, William R.

    1986-01-01

    A comprehensive study and development of instruments and techniques for measuring all components of flow in a storm-sewer drainage system were undertaken by the U. S. Geological Survey under the sponsorship of FHWA. The study involved laboratory and field calibration and testing of measuring flumes, pipe insert meters, weirs, and electromagnetic velocity meters as well as the development and calibration of pneumatic bubbler and pressure transducer head-measuring systems. Tracer dilution and acoustic-flowmeter measurements were used in field verification tests. A single micrologger was used to record data from all the instruments and also to activate on command the electromagnetic velocity meter and tracer dilution systems.

  7. Flow measurements in sewers based on image analysis: automatic flow velocity algorithm.

    PubMed

    Jeanbourquin, D; Sage, D; Nguyen, L; Schaeli, B; Kayal, S; Barry, D A; Rossi, L

    2011-01-01

    Discharges of combined sewer overflows (CSOs) and stormwater are recognized as an important source of environmental contamination. However, the harsh sewer environment and particular hydraulic conditions during rain events reduce the reliability of traditional flow measurement probes. An in situ system for sewer water flow monitoring based on video images was evaluated. Algorithms to determine water velocities were developed based on image-processing techniques. The image-based water velocity algorithm identifies surface features and measures their positions with respect to real world coordinates. A web-based user interface and a three-tier system architecture enable remote configuration of the cameras and the image-processing algorithms in order to calculate automatically flow velocity on-line. Results of investigations conducted in a CSO are presented. The system was found to measure reliably water velocities, thereby providing the means to understand particular hydraulic behaviors.

  8. Dynamic wall shear stress measurements in a turbulent channel flow

    NASA Astrophysics Data System (ADS)

    Amili, Omid; Soria, Julio

    2010-11-01

    To quantify and understand the dynamics of near wall momentum transfer, high spatial resolution, time-resolved measurements of wall shear stress distribution are essential. In this study, a film-based shear stress sensor has been used to measure the time-resolved local wall shear stress distribution in a turbulent channel flow. Measurements have been undertaken in a turbulent channel flow at Reynolds numbers up to 130,000 based on the bulk velocity and channel height. The measured fluctuating wall shear stress distribution provides spatio-temporal information of the characteristics of near wall structures by detecting their footprints. The span-wise extent of the positive two-point correlation of the stream-wise shear stress fluctuations provides the average width in the order of 100 wall units for the near-wall coherent structures. An investigation of the topological features of the velocity gradient and rate of strain tensors enables us to show an intrinsic characteristic of the near wall flow, which follows a two-dimensional flow pattern.

  9. Measurements of flow past a bileaflet mechanical heart valve

    NASA Astrophysics Data System (ADS)

    Haya, Laura; Tavoularis, Stavros

    2013-11-01

    A bileaflet mechanical heart valve has been inserted in an axisymmetric model of the aorta within a mock circulation apparatus with physiological pressure and flow variations. The velocity field behind the valve has been measured with laser Doppler velocimetry and particle image velocimetry. The results closely match those reported by similar studies. A triple jet emanated from the valve's orifices and regions of reverse flow formed in the sinus region. Velocity fluctuations were greatest in the shear layers of the jets. The average r.m.s. streamwise velocity fluctuation over the turbulent period was 0.22 m/s; its maximum value was 0.53 m/s and occurred at the onset of deceleration. Measurements with the valve inserted in an anatomical model of the aorta are planned for the near future. The present and future measurements will be compared to determine the effects of the aorta anatomy on the characteristics of flow through bileaflet valves. In particular, measurements of the viscous and turbulent shear stresses will be analyzed to identify possible locations of blood element damage, and regions of recirculation and stagnation will be identified as locations favourable to thrombus growth. The effects of flows in branching arteries and valve orientation will also be investigated. Supported by NSERC.

  10. [Measurement of cerebral blood flow by thermal diffusion using a flow probe with a Peltier stack].

    PubMed

    Yamagata, S; Kikuchi, H; Hashimoto, K; Minamikawa, J; Watanabe, Y

    1987-05-01

    In order to evaluate the blood flow by means of thermal diffusion, relationship between blood flow and parameters induced by thermal diffusion was investigated. Flow probe employed for measurement by thermal diffusion incorporated a Peltier stack which contained a small semiconductor and two L-shaped gold plates. These two plates were attached to both sides of the semiconductor by one side of each gold plate and the other side was surfaced with a tissue to be measured. Temperature gradient is created with current applied to the Peltier stack between two plates, one cooled and the other heated, and it is affected only by tissue blood flow. Two kinds of parameters of thermal diffusion were subjected to compare to blood flow. One was temperature gradient when the constant current was applied to the Peltier stack. The other was a current required to maintain a definite temperature gradient which was determined before hand. From the theoretical principle in thermodynamics, the correlations between blood flow and each of thermal diffusion parameters were defined by the following equations: (Formula: see text) where F is blood flow, delta V is voltage converted from temperature gradient, and Ci and Cv are constants. Each of phi v and phi i indicates the characteristics of each probe. Experimental study was carried out to confirm the above relationship using cortex of experimental animals. Under the general anesthesia, a cat was placed in prone position. After the craniotomy, dura mater was opened and a small flow probe, 10 mm in diameter, 5 mm in height and 5 g in weight, was placed on the cortex and blood flow was continuously evaluated by two parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Heat flow calorimeter. [measures output of Ni-Cd batteries

    NASA Technical Reports Server (NTRS)

    Fletcher, J. C.; Johnston, W. V. (Inventor)

    1974-01-01

    Heat flow calorimeter devices are used to measure heat liberated from or absorbed by an object. This device is capable of measuring the thermal output of sealed nickel-cadmium batteries or cells during charge-discharge cycles. An elongated metal heat conducting rod is coupled between the calorimeter vessel and a heat sink, thus providing the only heat exchange path from the calorimeter vessel itself.

  12. Measurements in Film Cooling Flows with Periodic Wakes

    DTIC Science & Technology

    2008-10-01

    camera, thermocouples, and constant current (cold- wire ) anemometry . Hot - wire anemometry was used for velocity measurements. The local film cooling...and constant temperature hot - wire anemometry were used to measure flow temperature and velocity, respectively. Boundary layer probes with 1.27 m...jet velocity and temperature were documented by Coulthard et al. 26 by traversing the constant current and hot - wire probes over the hole exit plane

  13. Abel Inversion of Deflectometric Measurements in Dynamic Flows

    NASA Technical Reports Server (NTRS)

    Agrawal, Ajay K.; Albers, Burt W.; Griffin, DeVon W.

    1999-01-01

    We present an Abel-inversion algorithm to reconstruct mean and rms refractive-index profiles from spatially resolved statistical measurements of the beam-deflection angle in time-dependent, axisymmetric flows. An oscillating gas-jet diffusion flame was investigated as a test case for applying the algorithm. Experimental data were obtained across the whole field by a rainbow schlieren apparatus. Results show that simultaneous multipoint measurements are necessary to reconstruct the rms refractive index accurately.

  14. Continuous heatable Langmuir probe for flowing afterglow measurements

    NASA Astrophysics Data System (ADS)

    Laubé, Sylvain; Mostefaoui, Toufik; Rowe, Bertrand

    2000-02-01

    A heatable Langmuir probe consisting of a continuous dc-heating-current loop of tungsten wire is presented. This technique is efficient to keep the probe surface clean for flowing afterglow measurements. In our experimental conditions, the perturbations on the electron density determination can be considered as very small. The measurement of the well-known rate for the dissociative recombination of O2+ shows that the gas surrounding the probe is not heated for estimated probe temperature up to 700 K.

  15. Examining School Security Measures as Moderators of the Association between Homophobic Victimization and School Avoidance

    ERIC Educational Resources Information Center

    Fisher, Benjamin W.; Tanner-Smith, Emily E.

    2015-01-01

    Homophobic victimization is a pervasive problem in U.S. schools that leads to negative outcomes for students. Those who experience homophobic victimization are at greater risk for avoiding particular spaces in school because they feel unsafe or afraid. Visible school security measures (e.g., security guards, metal detectors, and cameras) offer…

  16. Examining School Security Measures as Moderators of the Association between Homophobic Victimization and School Avoidance

    ERIC Educational Resources Information Center

    Fisher, Benjamin W.; Tanner-Smith, Emily E.

    2016-01-01

    Homophobic victimization is a pervasive problem in U.S. schools that leads to negative outcomes for students. Those who experience homophobic victimization are at greater risk for avoiding particular spaces in school because they feel unsafe or afraid. Visible school security measures (e.g., security guards, metal detectors, and cameras) offer…

  17. Method and apparatus for measuring coupled flow, transport, and reaction processes under liquid unsaturated flow conditions

    DOEpatents

    McGrail, Bernard P.; Martin, Paul F.; Lindenmeier, Clark W.

    1999-01-01

    The present invention is a method and apparatus for measuring coupled flow, transport and reaction processes under liquid unsaturated flow conditions. The method and apparatus of the present invention permit distinguishing individual precipitation events and their effect on dissolution behavior isolated to the specific event. The present invention is especially useful for dynamically measuring hydraulic parameters when a chemical reaction occurs between a particulate material and either liquid or gas (e.g. air) or both, causing precipitation that changes the pore structure of the test material.

  18. Plasma dragged microparticles as a method to measure plasma flows

    SciTech Connect

    Ticos, Catalin M.; Wang Zhehui; Delzanno, Gian Luca; Lapenta, Giovanni

    2006-10-15

    The physics of microparticle motion in flowing plasmas is studied in detail for plasmas with electron and ion densities n{sub e,i}{approx}10{sup 19} m{sup -3}, electron and ion temperatures of no more than 15 eV, and plasma flows on the order of the ion thermal speed, v{sub f}{approx}v{sub ti}. The equations of motion due to Coulomb interactions and direct impact with ions and electrons, of charge variation, as well as of heat exchange with the plasma, are solved numerically for isolated particles (or dust grains) of micron sizes. It is predicted that microparticles can survive in plasma long enough, and can be dragged in the direction of the local ion flow. Based on the theoretical analysis, we describe a new plasma flow measurement technique called microparticle tracer velocimetry (mPTV), which tracks microparticle motion in a plasma with a high-speed camera. The mPTV can reveal the directions of the plasma flow vectors at multiple locations simultaneously and at submillimeter scales, which is hard to achieve by most other techniques. Thus, mPTV can be used to study plasma flows produced in the laboratory.

  19. Observations and Measurements on Unsteady Cloud Cavitation Flow Structures

    NASA Astrophysics Data System (ADS)

    Gu, L. X.; Yan, G. J.; Huang, B.

    2015-12-01

    The objectives of this paper are to investigate the unsteady structures and hydrodynamics of cavitating flows. Experimental results are presented for a Clark-Y hydrofoil, which is fixed at α=0°, 5° and 8°. The high-speed video camera and Particle Image Velocimetry (PIV) are applied to investigate the transient flow structures. The dynamic measurement system is used to record the dynamic characteristics. The cloud cavitation exhibits noticeable unsteady characteristics. For the case of α=0°, there exit strong interactions between the attached cavity and the re-entrant flow. While for the case of α=8°, the re-entrant flow is relatively thin and the interaction between the cavity and re-entrant flow is limited. The results also present that the periodic collapse and shedding of the large-scale cloud cavitation, which leads to substantial increase of turbulent velocity fluctuations in the cavity region. Experimental evidence indicates that the hydrodynamics are clearly affected by the cavitating flow structures, the amplitude of load fluctuation are much higher for the cloud cavitating cases.

  20. Measurements of turbulent flow overlying impermeable and permeable walls

    NASA Astrophysics Data System (ADS)

    Kim, Taehoon; Blois, Gianluca; Best, James; Christensen, Kenneth

    2016-11-01

    There exist an array of natural and industrial flow systems wherein the flow is bounded by a surface that is both permeable and rough (e.g. river beds, bed reactors). In such scenarios, the wall boundary condition is complex as it involves both slip and penetration which together significantly modify the statistical and structural modifications the overlying flow owing to momentum exchange across the wall. The current investigation explores the individual roles of topography and permeability in such flows by systematically decoupling one from the other with a number of wall models having the same porous structure (i.e. cubically arranged spheres; two and five layers, respectively, to highlight the effect of turbulence penetration depth) but with different surface topography (smooth versus cubically arranged hemispheres). High resolution particle-image velocimetry measurements were conducted in the streamwise-wall-normal (x - y) plane and refractive-index matching was employed to optically access the flow within the permeable wall. First- and second-order velocity statistics are used to assess the flow modifications associated with the different wall models and thus ascertain the individual impacts of permeability and topography. NSF.

  1. Jet-Surface Interaction Test: Flow Measurements Results

    NASA Technical Reports Server (NTRS)

    Brown, Cliff; Wernet, Mark

    2014-01-01

    Modern aircraft design often puts the engine exhaust in close proximity to the airframe surfaces. Aircraft noise prediction tools must continue to develop in order to meet the challenges these aircraft present. The Jet-Surface Interaction Tests have been conducted to provide a comprehensive quality set of experimental data suitable for development and validation of these exhaust noise prediction methods. Flow measurements have been acquired using streamwise and cross-stream particle image velocimetry (PIV) and fluctuating surface pressure data acquired using flush mounted pressure transducers near the surface trailing edge. These data combined with previously reported far-field and phased array noise measurements represent the first step toward the experimental data base. These flow data are particularly applicable to development of noise prediction methods which rely on computational fluid dynamics to uncover the flow physics. A representative sample of the large flow data set acquired is presented here to show how a surface near a jet affects the turbulent kinetic energy in the plume, the spatial relationship between the jet plume and surface needed to generate surface trailing-edge noise, and differences between heated and unheated jet flows with respect to surfaces.

  2. A smart flow measurement system for flow evaluation with multiple signals in different operation modes

    NASA Astrophysics Data System (ADS)

    Kaltsas, G.; Katsikogiannis, P.; Asimakopoulos, P.; Nassiopoulou, A. G.

    2007-11-01

    This paper presents the development and evaluation of a smart flow measurement system based on an integrated thermal flow sensor that implements a heater and two pairs of thermopiles, symmetrically situated on both sides of the heater. A specially designed interface circuit monitors and controls sensor operation, allowing three different operational modes: constant voltage (CV), constant power (CP) and constant temperature (CT). It also simultaneously monitors the heater resistance and the thermopile signal. Communication with a PC is implemented through a USB connection, and a developed Java program controls the system and data representation and storage. Transfer rates in the order of 20 000 sps are achieved, which allow detailed flow monitoring. For system evaluation, flow measurements were performed in both the calorimetric and hot-wire principles with the three different modes of operation and the corresponding results are presented comparatively. Flow velocity was determined by different sensor signals (heater resistance and power, thermopile signal) and the related sensitivities were extracted. Furthermore, it was verified that the system could detect the flow direction as well as the transition point from laminar to turbulent region.

  3. Measurements of Gas Bubble Size Distributions in Flowing Liquid Mercury

    SciTech Connect

    Wendel, Mark W; Riemer, Bernie; Abdou, Ashraf A

    2012-01-01

    ABSTRACT Pressure waves created in liquid mercury pulsed spallation targets have been shown to induce cavitation damage on the target container. One way to mitigate such damage would be to absorb the pressure pulse energy into a dispersed population of small bubbles, however, measuring such a population in mercury is difficult since it is opaque and the mercury is involved in a turbulent flow. Ultrasonic measurements have been attempted on these types of flows, but the flow noise can interfere with the measurement, and the results are unverifiable and often unrealistic. Recently, a flow loop was built and operated at Oak Ridge National Labarotory to assess the capability of various bubbler designs to deliver an adequate population of bubbles to mitigate cavitation damage. The invented diagnostic technique involves flowing the mercury with entrained gas bubbles in a steady state through a horizontal piping section with a glass-window observation port located on the top. The mercury flow is then suddenly stopped and the bubbles are allowed to settle on the glass due to buoyancy. Using a bright-field illumination and a high-speed camera, the arriving bubbles are detected and counted, and then the images can be processed to determine the bubble populations. After using this technique to collect data on each bubbler, bubble size distributions were built for the purpose of quantifying bubbler performance, allowing the selection of the best bubbler options. This paper presents the novel procedure, photographic technique, sample visual results and some example bubble size distributions. The best bubbler options were subsequently used in proton beam irradiation tests performed at the Los Alamos National Laboratory. The cavitation damage results from the irradiated test plates in contact with the mercury are available for correlation with the bubble populations. The most effective mitigating population can now be designed into prototypical geometries for implementation into

  4. Measurement of Flow Phenomena in a VHTR Lower Plenum Model

    SciTech Connect

    Hugh M. McIlroy Jr.; Donald M. McEligot; Robert J. Pink

    2007-06-01

    Mean velocity and turbulence data that measure turbulent flow phenomena in an approximately 1:7 scale model of a region of the lower plenum of a typical prismatic gas-cooled reactor are presented as a follow-up to summaries presented at the 2006 Annual Meeting and the 2006 Winter Meeting. The experiments were designed to develop benchmark databases to support the first Standard Problem endorsed by the Generation IV International Forum to validate the heat transfer and fluid flow software that will be used to study the behavior of the VHTR system.

  5. Two-phase flow measurements with advanced instrumented spool pieces

    SciTech Connect

    Turnage, K.C.

    1980-09-01

    A series of two-phase, air-water and steam-water tests performed with instrumented piping spool pieces is described. The behavior of the three-beam densitometer, turbine meter, and drag flowmeter is discussed in terms of two-phase models. Results from application of some two-phase mass flow models to the recorded spool piece data are shown. Results of the study are used to make recommendations regarding spool piece design, instrument selection, and data reduction methods to obtain more accurate measurements of two-phase flow parameters. 13 refs., 23 figs., 1 tab.

  6. [Measurement of cerebral blood flow using phase-contrast MRI].

    PubMed

    Obata, T; Shishido, F; Koga, M; Ikehira, H; Kimura, F; Yoshida, K

    1997-07-01

    The development of phase-contrast magnetic resonance imaging(P-C MRI) provides a noninvasive method for measurement of volumetric blood flow(VFR). The VFR of the left and right internal carotid arteries and basilar artery were measured using P-C MRI, and total cerebral blood flow(tCBF) was calculated by summing up the VFR values in three vessels. We investigated the changes in these blood flows as influenced from age, head size, height, weight, body surface area and handedness. Moreover, regional CBF(rCBF) was measured by combining with the single photon emission computed tomography(SPECT) of 123I. The blood flows were 142 +/- 58 mL/ min(mean +/- SD) in the basilar artery, 229 +/- 86 mL/min in the left, 223 +/- 58 mL/min in the right internal carotid artery, and tCBF was 617 +/- 128 mL/min(Ref. Magn Resn Imaging 14:P. 1143, 1996). Significant increases were observed in head-size-related change of VFR in the basilar artery and height-related change of tCBF. The value of rCBF was easily acquired in combination with SPECT. Phase-contrast MRI is useful for a noninvasive and rapid analysis of cerebral VFR and has potential for clinical use.

  7. Rotating permanent magnet excitation for blood flow measurement.

    PubMed

    Nair, Sarath S; Vinodkumar, V; Sreedevi, V; Nagesh, D S

    2015-11-01

    A compact, portable and improved blood flow measurement system for an extracorporeal circuit having a rotating permanent magnetic excitation scheme is described in this paper. The system consists of a set of permanent magnets rotating near blood or any conductive fluid to create high-intensity alternating magnetic field in it and inducing a sinusoidal varying voltage across the column of fluid. The induced voltage signal is acquired, conditioned and processed to determine its flow rate. Performance analysis shows that a sensitivity of more than 250 mV/lpm can be obtained, which is more than five times higher than conventional flow measurement systems. Choice of rotating permanent magnet instead of an electromagnetic core generates alternate magnetic field of smooth sinusoidal nature which in turn reduces switching and interference noises. These results in reduction in complex electronic circuitry required for processing the signal to a great extent and enable the flow measuring device to be much less costlier, portable and light weight. The signal remains steady even with changes in environmental conditions and has an accuracy of greater than 95%. This paper also describes the construction details of the prototype, the factors affecting sensitivity and detailed performance analysis at various operating conditions.

  8. Simultaneous 3D Strain and Flow Fields Measurement of a Model Artery under Unsteady Flows

    NASA Astrophysics Data System (ADS)

    Toloui, Mostafa; Sheng, Jian

    2011-11-01

    Fluid-Structure Interaction imposes challenges in both aero-elasticity and biomedical studies. A simultaneous solid deformation and fluid flow measurement technique based on digital in-line holographic particle tracking velocimetry (PTV) has been developed. It allows us to measure concurrently 3D strain field of a deforming structure and the unsteady flow near it. To facilitate the measurement, both wall and flow are seeded with tracer particles distinguished by size. The motion of these tracers provides the 3D deformation of the wall and the 3D velocity distribution of the flow separately. A fully index matched facility including transparent artery and NaI solution is constructed to enable observations near the wall or through the complex geometry. An arterial model with the inner diameter of 9.5 mm and the thickness of 0.9 mm is manufactured from the cross-linked transparent PDMS at the mixing ratio of 1:10 and doped with mono-dispersed 19 μm polystyrene particles. A cinematic holographic PTV system is used to trace the 3D particle motion in the model and flow simultaneously. Preliminary study is performed within a sample volume of 15 × 15 × 75 mm with the spatial resolution of 7.4 μm in lateral and 10 μm in depth. Uncertainty and accuracy analysis will be reported. NSF Grant No: CBET-0844647.

  9. Experimental Investigation of Effects of Moderate Sideslip on the Flow Fields near a 45 Degree Swept-wing-fuselage Combination at Low Speed

    NASA Technical Reports Server (NTRS)

    Alford, William J , Jr; King, Thomas J , Jr

    1957-01-01

    The flow fields near a 45 degree swept-wing-fuselage combination at moderate angles of sideslip (plus-or-minus 8 degrees), as determined experimentally at low speed, are presented as variations with chordwise distance for various spanwise and vertical locations and angles of attack. The results indicated that for positions close to the fuselage (on and near the plane of symmetry) changes in the angle of sideslip caused large changes in the flow-field characteristics and particularly in the local angles of sideslip, which in some cases were nearly double the static angle of sideslip. In general, the effects of changing the angle of sideslip on the flow-field characteristics for all of the outboard underwing locations were qualitatively similar, although conditions at the more inboard and outboard locations were somewhat more severe for lifting conditions than at the one-half semispan location. The chordwise gradients in the flow parameters for the underwing locations were more severe than for the fuselage locations although the effect of changing the angle of sideslip was less severe, in that the incremental changes in the local angles of sideslip were approximately equal to the static angle of sideslip. Flow conditions near the wing tip were found to be critically dependent on vertical location, with the largest sideslip-induced variations occurring at the nearest vertical locations. The results also indicated that for the outboard underwing locations the wing was the predominant factor in disturbing the field of flow for the conditions investigated.

  10. The physiological links of the increased photosystem II activity in moderately desiccated Porphyra haitanensis (Bangiales, Rhodophyta) to the cyclic electron flow during desiccation and re-hydration.

    PubMed

    Gao, Shan; Niu, Jianfeng; Chen, Weizhou; Wang, Guangce; Xie, Xiujun; Pan, Guanghua; Gu, Wenhui; Zhu, Daling

    2013-09-01

    Photosynthetic electron flow changed considerably during desiccation and re-hydration of the intertidal macroalgae Porphyra haitanensis. Activities of both photosystem (PSI) and photosystem (PSII) increased significantly at moderate desiccation levels. Whereas PSII activity was abolished at an absolute water content (AWC) <24 %, PSI remained active with progressive decreases in AWC to values as low as 16 %. This result suggested that cyclic electron flow around PSI was still active after inactivation of linear electron flow following severe desiccation. Moreover, the PSI activity was restored more rapidly than that of PSII upon re-hydration. Pretreatment of the blades with 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) suppressed PSII activity following desiccation to an AWC of ~16 % AWC. Cyclic electron flow around PSI decreased markedly in blades pretreated with DCMU than in blades without pretreatment of DCMU during re-hydration in seawater containing DCMU. All results suggested that the activity of PSII under desiccation conditions plays an important role in the operation of cyclic electron flow during desiccation and its recovery during re-hydration. Therefore, we proposed the PSII activity during desiccation could eventually lead to the accumulation of NADPH, which could serve as electron donor for P700(+) and promote its recovery during re-hydration, thereby favoring the operation of cyclic electron flow.

  11. Earth's field NMR flow meter: preliminary quantitative measurements.

    PubMed

    Fridjonsson, Einar O; Stanwix, Paul L; Johns, Michael L

    2014-08-01

    In this paper we demonstrate the use of Earth's field NMR (EF NMR) combined with a pre-polarising permanent magnet for measuring fast fluid velocities. This time of flight measurement protocol has a considerable history in the literature; here we demonstrate that it is quantitative when employing the Earth's magnetic field for signal detection. NMR signal intensities are measured as a function of flow rate (0-1m/s) and separation distance between the permanent magnet and the EF NMR signal detection. These data are quantitatively described by a flow model, ultimately featuring no free parameters, that accounts for NMR signal modulation due to residence time inside the pre-polarising magnet, between the pre-polarising magnet and the detection RF coil and inside the detection coil respectively. The methodology is subsequently demonstrated with a metallic pipe in the pre-polarising region.

  12. Torque Transient of Magnetically Drive Flow for Viscosity Measurement

    NASA Technical Reports Server (NTRS)

    Ban, Heng; Li, Chao; Su, Ching-Hua; Lin, Bochuan; Scripa, Rosalia N.; Lehoczky, Sandor L.

    2004-01-01

    Viscosity is a good indicator of structural changes for complex liquids, such as semiconductor melts with chain or ring structures. This paper discusses the theoretical and experimental results of the transient torque technique for non-intrusive viscosity measurement. Such a technique is essential for the high temperature viscosity measurement of high pressure and toxic semiconductor melts. In this paper, our previous work on oscillating cup technique was expanded to the transient process of a magnetically driven melt flow in a damped oscillation system. Based on the analytical solution for the fluid flow and cup oscillation, a semi-empirical model was established to extract the fluid viscosity. The analytical and experimental results indicated that such a technique has the advantage of short measurement time and straight forward data analysis procedures

  13. Simultaneous measurements of air-sea gas transfer velocity and near surface turbulence at low to moderate winds (Invited)

    NASA Astrophysics Data System (ADS)

    Wang, B.; Liao, Q.; Fillingham, J. H.; Bootsma, H. A.

    2013-12-01

    Parameterization of air-sea gas transfer velocity was routinely made with wind speed. Near surface turbulent dissipation rate has been shown to have better correlation with the gas transfer velocity in a variety of aquatic environments (i.e., the small eddy model) while wind speed is low to moderate. Wind speed model may underestimate gas transfer velocity at low to moderate winds when the near surface turbulence is produced by other environmental forcing. We performed a series of field experiments to measure the CO2 transfer velocity, and the statistics of turbulence immediately below the air-water interface using a novel floating PIV and chamber system. The small eddy model was evaluated and the model coefficient was found to be a non-constant, and it varies with the local turbulent level (figure 1). Measure results also suggested an appropriate scaling of the vertical dissipation profile immediately below the interface under non-breaking conditions, which can be parameterized by the wind shear, wave height and wave age (figure 2). Figure 1. Relation between the coefficient of the small eddy model and dissipation rate. The data also include Chu & Jirka (2003) and Vachon et al. (2010). The solid regression line: α = 0.188log(ɛ)+1.158 Figure 2. Non-dimensional dissipation profiles. Symbols: measured data with the floating PIV. Solid line: regression of measured data with a -0.79 decaying rate. Dash line with -2 slope: Terray et al. (1996) relation. Dash line with two layer structure: Siddiqui & Loewen (2007) relation.

  14. Adenosine mediates decreased cerebral metabolic rate and increased cerebral blood flow during acute moderate hypoxia in the near-term fetal sheep.

    PubMed

    Blood, Arlin B; Hunter, Christian J; Power, Gordon G

    2003-12-15

    Exposure of the fetal sheep to moderate to severe hypoxic stress results in both increased cortical blood flow and decreased metabolic rate. Using intravenous infusion of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective adenosine A1 receptor antagonist that is permeable to the blood brain barrier, we examine the role of adenosine A1 receptors in mediating cortical blood flow and metabolic responses to moderate hypoxia. The effects of DPCPX blockade are compared to controls as well as animals receiving intravenous 8-(p-sulfophenyl)-theophylline) (8-SPT), a non-selective adenosine receptor antagonist which has been found to be blood brain barrier impermeable. Laser Doppler flow probes, tissue PO2, and thermocouples were implanted in the cerebral cortices of near-term fetal sheep. Catheters were placed in the brachial artery and sagittal sinus vein for collection of samples for blood gas analysis. Three to seven days later responses to a 30-min period of fetal hypoxemia (arterial PO2 10-12 mmHg) were studied with administration of 8-SPT, DPCPX, or vehicle. Cerebral metabolic rate was determined by calculation of both brain heat production and oxygen consumption. In response to hypoxia, control experiments demonstrated a 42 +/- 7 % decrease in cortical heat production and a 35 +/- 10 % reduction in oxygen consumption. In contrast, DPCPX infusion during hypoxia resulted in no significant change in brain heat production or oxygen consumption, suggesting the adenosine A1 receptor is involved in lowering metabolic rate during hypoxia. The decrease in cerebral metabolic rate was not altered by 8-SPT infusion, suggesting that the response is not mediated by adenosine receptors located outside the blood brain barrier. In response to hypoxia, control experiments demonstrated a 35 +/- 7 % increase in cortical blood flow. DPCPX infusion did not change this increase in cortical blood flow, however 8-SPT infusion attenuated increases in flow, indicating that hypoxic

  15. Inductive plethysmography potential as a surrogate for ventilatory measurements during rest and moderate physical exercise

    PubMed Central

    Cabiddu, Ramona; Pantoni, Camila B. F.; Mendes, Renata G.; Trimer, Renata; Catai, Aparecida M.; Borghi-Silva, Audrey

    2016-01-01

    Background: Portable respiratory inductive plethysmography (RIP) systems have been validated for ventilatory assessment during resting conditions and during incremental treadmill exercise. However, in clinical settings and during field-based exercise, intensity is usually constant and submaximal. A demonstration of the ability of RIP to detect respiratory measurements accurately during constant intensity conditions would promote and validate the routine use of portable RIP devices as an alternative to ergospirometry (ES), the current gold standard technique for ventilatory measures. Objective: To investigate the agreement between respiratory variables recorded by a portable RIP device and by ES during rest and constant intensity exercise. Method: Tidal volume (VT), respiratory rate (RR) and minute ventilation (VE) were concurrently acquired by portable RIP and ES in seven healthy male volunteers during standing rest position and constant intensity treadmill exercise. Results: Significant agreement was found between RIP and ES acquisitions during the standing rest position and constant intensity treadmill exercise for RR and during the standing rest position for VE. Conclusion: Our results suggest that portable RIP devices might represent a suitable alternative to ES during rest and during constant submaximal exercise. PMID:26982454

  16. Characterizing pulmonary blood flow distribution measured using arterial spin labeling.

    PubMed

    Henderson, A Cortney; Prisk, G Kim; Levin, David L; Hopkins, Susan R; Buxton, Richard B

    2009-12-01

    The arterial spin labeling (ASL) method provides images in which, ideally, the signal intensity of each image voxel is proportional to the local perfusion. For studies of pulmonary perfusion, the relative dispersion (RD, standard deviation/mean) of the ASL signal across a lung section is used as a reliable measure of flow heterogeneity. However, the RD of the ASL signals within the lung may systematically differ from the true RD of perfusion because the ASL image also includes signals from larger vessels, which can reflect the blood volume rather than blood flow if the vessels are filled with tagged blood during the imaging time. Theoretical studies suggest that the pulmonary vasculature exhibits a lognormal distribution for blood flow and thus an appropriate measure of heterogeneity is the geometric standard deviation (GSD). To test whether the ASL signal exhibits a lognormal distribution for pulmonary blood flow, determine whether larger vessels play an important role in the distribution, and extract physiologically relevant measures of heterogeneity from the ASL signal, we quantified the ASL signal before and after an intervention (head-down tilt) in six subjects. The distribution of ASL signal was better characterized by a lognormal distribution than a normal distribution, reducing the mean squared error by 72% (p < 0.005). Head-down tilt significantly reduced the lognormal scale parameter (p = 0.01) but not the shape parameter or GSD. The RD increased post-tilt and remained significantly elevated (by 17%, p < 0.05). Test case results and mathematical simulations suggest that RD is more sensitive than the GSD to ASL signal from tagged blood in larger vessels, a probable explanation of the change in RD without a statistically significant change in GSD. This suggests that the GSD is a useful measure of pulmonary blood flow heterogeneity with the advantage of being less affected by the ASL signal from tagged blood in larger vessels.

  17. Holocene Flows of the Cima Volcanic Field, Mojave Desert, Part 2: Flow Rheology from Laboratory Measurements

    NASA Astrophysics Data System (ADS)

    Robertson, T.; Whittington, A. G.; Soldati, A.; Sehlke, A.; Beem, J. R.; Gomez, F. G.

    2014-12-01

    Lava flow morphology is often utilized as an indicator of rheological behavior during flow emplacement. Rheological behavior can be characterized by the viscosity and yield strength of lava, which in turn are dependent on physical and chemical properties including crystallinity, vesicularity, and bulk composition. We are studying the rheology of a basaltic lava flow from a monogenetic Holocene cinder cone in the Cima lava field (Mojave Desert, California). The flow is roughly 2.5 km long and up to 700m wide, with a well-developed central channel along much of its length. Samples were collected along seven different traverses across the flow, along with real-time kinematic (RTK) GPS profiles to allow levee heights and slopes to be measured. Surface textures change from pahoehoe ropes near the vent to predominantly jagged `a`a blocks over the majority of the flow, including all levees and the toe. Chemically the lava shows little variation, plotting on the trachybasalt-basanite boundary on the total alkali-silica diagram. Mineralogically the lava is dominated by plagioclase, clinopyroxene and olivine phenocrysts, with abundant flow-aligned plagioclase microcrystals. The total crystal fraction is ~50% near the vent, with higher percentages in the distal portion of the flow. Vesicularity varies between ~10 and more than ~60%. Levees are ~10-15m high with slopes typically ~25-35˚, suggesting a yield strength at final emplacement of ~150,000 Pa. The effective emplacement temperature and yield strength of lava samples will be determined using the parallel-plate technique. We will test the hypothesis that these physical and rheological properties of the lava during final emplacement correlate with spatial patterns in flow morphology, such as average slope and levee width, which have been determined using remote sensing observations (Beem et al. 2014).

  18. The GUINEVERE experiment: First PNS measurements in a lead moderated sub-critical fast core

    SciTech Connect

    Thyebault, H. E.; Billebaud, A.; Chabod, S.; Lecolley, F. R.; Lecouey, J. L.; Lehaut, G.; Marie, N.; Ban, G.

    2012-07-01

    The GUINEVERE (Generation of Uninterrupted Intense Neutrons at the lead Venus Reactor) experimental program is dedicated to the study of Accelerator Driven System reactivity monitoring. It was partly carried out within the EUROTRANS integrated project (EURATOM FP6). GUINEVERE consists in coupling the fast core of the VENUS-F reactor (SCK-CEN, Mol (Belgium)), composed of enriched uranium and solid lead, with a T(d,n) neutron source provided by the GENEPI-3C deuteron accelerator. This neutron source can be operated in several modes: pulsed mode, continuous mode and also continuous mode with short beam interruptions (the so called 'beam trips'). In the past, the key questions of the reactivity control and monitoring in a subcritical system were studied in the MUSE experiments (1998-2004). These experiments highlighted the difficulty to determine precisely the reactivity with a single technique. This led to investigate a new strategy which is based on the combination of the relative reactivity monitoring via the core power to beam current relationship with absolute reactivity cross-checks during programmed beam interruptions. Consequently, to determine the reactivity, several dynamical techniques of reactivity determination have to be compared. In addition, their accuracy for absolute reactivity determination must be evaluated using a reference reactivity determination technique (from a critical state: rod drop and MSM measurements). The first sub-critical configuration which was studied was around k{sub eff} = 0.96 (SCI). Pulsed Neutron Source experiments (PNS) were carried out. The neutron population decrease was measured using fission chambers in different locations inside the core and the reflector. Neutron population time decrease was analyzed using fitting techniques and the Area Method Results obtained for the SCI reactivity will be shown, discussed and compared to the reference value given by the MSM method. (authors)

  19. Flow measurement around a model ship with propeller and rudder

    NASA Astrophysics Data System (ADS)

    van, S. H.; Kim, W. J.; Yoon, H. S.; Lee, Y. Y.; Park, I. R.

    2006-04-01

    For the design of hull forms with better resistance and propulsive performance, it is essential to understand flow characteristics, such as wave and wake development, around a ship. Experimental data detailing the local flow characteristics are invaluable for the validation of the physical and numerical modeling of computational fluid dynamics (CFD) codes, which are recently gaining attention as efficient tools for hull form evaluation. This paper describes velocity and wave profiles measured in the towing tank for the KRISO 138,000 m3 LNG carrier model with propeller and rudder. The effects of propeller and rudder on the wake and wave profiles in the stern region are clearly identified. The results contained in this paper can provide an opportunity to explore integrated flow phenomena around a model ship in the self-propelled condition, and can be added to the International Towing Tank Conference benchmark data for CFD validation as the previous KCS and KVLCC cases.

  20. Non-intrusive flow measurements on a reentry vehicle

    NASA Technical Reports Server (NTRS)

    Miles, R. B.; Satavicca, D. A.; Zimmermann, G. M.

    1983-01-01

    This study evaluates the utility of various non-intrusive techniques for the measurement of the flow field on the windward side of the Space Shuttle or a similar re-entry vehicle. Included are linear (Rayleigh, Raman, Mie, Laser Doppler Velocimetry, Resonant Doppler Velocimetry) and nonlinear (Coherent Anti-Stokes Raman, Laser Induced Fluorescence) light scattering, electron beam fluorescence, thermal emission and mass spectroscopy. Flow field properties are taken from a nonequilibrium flow model by Shinn, Moss and Simmonds at NASA Langley. Conclusions are, when possible, based on quantitative scaling of known laboratory results to the conditions projected. Detailed discussion with researchers in the field contributed further to these conclusions and provided valuable insights regarding the experimental feasibility of each of the techniques.

  1. Mass flow measurement of liquid cryogens using the triboelectric effect

    NASA Technical Reports Server (NTRS)

    Dechene, Ronald L.

    1986-01-01

    A cross correlator technique using triboelectric technology has been shown to be a feasible method to measure liquid flow rate for liquid nitrogen and JP4 jet fuel. This technology, invented and pioneered by Auburn International, Inc., is also expected to be suitable for use with all other insulating liquids and cryogens. The technology described is particularly well suited for cryogenic use, since the sensor is non-contacting and non-intrusive, and therefore, causes no additional pressure drop within the flow stream. Further development of the in-line sensor is required to produce a prototypical version for the test purposes under SSME fuel flow conditions. However, with the knowledge gained from this feasibility study, it is very likely that an acceptable sensor design for a full test bed evaluation could be produced.

  2. Optical Air Flow Measurements for Flight Tests and Flight Testing Optical Air Flow Meters

    NASA Technical Reports Server (NTRS)

    Jentink, Henk W.; Bogue, Rodney K.

    2005-01-01

    Optical air flow measurements can support the testing of aircraft and can be instrumental to in-flight investigations of the atmosphere or atmospheric phenomena. Furthermore, optical air flow meters potentially contribute as avionics systems to flight safety and as air data systems. The qualification of these instruments for the flight environment is where we encounter the systems in flight testing. An overview is presented of different optical air flow measurement techniques applied in flight and what can be achieved with the techniques for flight test purposes is reviewed. All in-flight optical airflow velocity measurements use light scattering. Light is scattered on both air molecules and aerosols entrained in the air. Basic principles of making optical measurements in flight, some basic optical concepts, electronic concepts, optoelectronic interfaces, and some atmospheric processes associated with natural aerosols are reviewed. Safety aspects in applying the technique are shortly addressed. The different applications of the technique are listed and some typical examples are presented. Recently NASA acquired new data on mountain rotors, mountain induced turbulence, with the ACLAIM system. Rotor position was identified using the lidar system and the potentially hazardous air flow profile was monitored by the ACLAIM system.

  3. SAPFLUXNET: towards a global database of sap flow measurements.

    PubMed

    Poyatos, Rafael; Granda, Víctor; Molowny-Horas, Roberto; Mencuccini, Maurizio; Steppe, Kathy; Martínez-Vilalta, Jordi

    2016-12-01

    Plant transpiration is the main evaporative flux from terrestrial ecosystems; it controls land surface energy balance, determines catchment hydrological responses and influences regional and global climate. Transpiration regulation by plants is a key (and still not completely understood) process that underlies vegetation drought responses and land evaporative fluxes under global change scenarios. Thermometric methods of sap flow measurement have now been widely used to quantify whole-plant and stand transpiration in forests, shrublands and orchards around the world. A large body of research has applied sap flow methods to analyse seasonal and diurnal patterns of transpiration and to quantify their responses to hydroclimatic variability, but syntheses of sap flow data at regional to global scales are extremely rare. Here we present the SAPFLUXNET initiative, aimed at building the first global database of plant-level sap flow measurements. A preliminary metadata survey launched in December 2015 showed an encouraging response by the sap flow community, with sap flow data sets from field studies representing >160 species and >120 globally distributed sites. The main goal of SAPFLUXNET is to analyse the ecological factors driving plant- and stand-level transpiration. SAPFLUXNET will open promising research avenues at an unprecedented global scope, namely: (i) exploring the spatio-temporal variability of plant transpiration and its relationship with plant and stand attributes, (ii) summarizing physiological regulation of transpiration by means of few water-use traits, usable for land surface models, (iii) improving our understanding of the coordination between gas exchange and plant-level traits (e.g., hydraulics) and (iv) analysing the ecological factors controlling stand transpiration and evapotranspiration partitioning. Finally, SAPFLUXNET can provide a benchmark to test models of physiological controls of transpiration, contributing to improve the accuracy of

  4. Interfacial characteristic measurements in horizontal bubbly two-phase flow

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Huang, W. D.; Srinivasmurthy, S.; Kocamustafaogullari, G.

    1990-10-01

    Advances in the study of two-phase flow increasingly require detailed internal structure information upon which theoretical models can be formulated. The void fraction and interfacial area are two fundamental parameters characterizing the internal structure of two-phase flow. However, little information is currently available on these parameters, and it is mostly limited to vertical flow configurations. In view of the above, the internal phase distribution of concurrent, air-water bubbly flow in a 50.3 mm diameter transparent pipeline has been experimentally investigated by using a double-sensor resistivity probe. Liquid and gas volumetric superficial velocities ranged from 3.74 to 5.60 m/s and 0.25 to 1.59 m/s, respectively, and average void fractions ranged from 2.12 to 22.5 percent. The local values of void fractions, interfacial area concentration, mean bubble diameter, bubble interface velocity, bubble chord-length and bubble frequency distributions were measured. The experimental results indicate that the void fraction interfacial area concentration and bubble frequency have local maxima near the upper pipe wall, and the profiles tend to flatten with increasing void fraction. The observed peak void fraction can reach 0.65, the peak interfacial area can go up to 900 approximately 1000 sq m/cu m, and the bubble frequency can reach a value of 2200 per s. These ranges of values have never been reported for vertical bubbly flow. It is found that either decreasing the liquid flow rate or increasing the gas flow would increase the local void fraction, the interfacial area concentration and the bubble frequency.

  5. Measurement Requirements for Improved Modeling of Arcjet Facility Flows

    NASA Technical Reports Server (NTRS)

    Fletcher, Douglas G.

    2000-01-01

    Current efforts to develop new reusable launch vehicles and to pursue low-cost robotic planetary missions have led to a renewed interest in understanding arc-jet flows. Part of this renewed interest is concerned with improving the understanding of arc-jet test results and the potential use of available computational-fluid- dynamic (CFD) codes to aid in this effort. These CFD codes have been extensively developed and tested for application to nonequilibrium, hypersonic flow modeling. It is envisioned, perhaps naively, that the application of these CFD codes to the simulation of arc-jet flows would serve two purposes: first. the codes would help to characterize the nonequilibrium nature of the arc-jet flows; and second. arc-jet experiments could potentially be used to validate the flow models. These two objectives are, to some extent, mutually exclusive. However, the purpose of the present discussion is to address what role CFD codes can play in the current arc-jet flow characterization effort, and whether or not the simulation of arc-jet facility tests can be used to eva1uate some of the modeling that is used to formu1ate these codes. This presentation is organized into several sections. In the introductory section, the development of large-scale, constricted-arc test facilities within NASA is reviewed, and the current state of flow diagnostics using conventional instrumentation is summarized. The motivation for using CFD to simulate arc-jet flows is addressed in the next section, and the basic requirements for CFD models that would be used for these simulations are briefly discussed. This section is followed by a more detailed description of experimental measurements that are needed to initiate credible simulations and to evaluate their fidelity in the different flow regions of an arc-jet facility. Observations from a recent combined computational and experiment.al investigation of shock-layer flows in a large-scale arc-jet facility are then used to illustrate the

  6. Noninvasive fluid flow measurements in microfluidic channels with backscatter interferometry.

    PubMed

    Markov, Dmitry A; Dotson, Stephen; Wood, Scott; Bornhop, Darryl J

    2004-11-01

    The ability to measure fluid velocity within picoliter volumes or on-chip noninvasively, is important toward fully realizing the potential of microfluidics and micrototal analysis systems, particularly in applications such as micro-high-performance liquid chromatography (HPLC) or in metering mixing where the flow rate must be quantified. Additionally, these measurements need to be performed directly on moving fluids in a noninvasive fashion. We presented here the proof of principle experiments showing nonintrusive fluid flow measurements can be accomplished on-chip using a pump and probe configuration with backscattering interferometry. The on-chip interferometric backscatter detector (OCIBD) is based on a fiber-coupled HeNe laser that illuminates a portion of an isotropically etched 40 microm radius channel and a position sensitive transducer to measure fringe pattern shifts. An infrared laser with a mechanical shutter is used to heat a section of a flowing volume and the resulting refractive index (RI) change is detected with the OCIBD downstream as a time-dependent RI perturbation. Fluid velocity is quantified as changes in the phase difference between the shutter signal and the OCIBD detected signal in the Fourier domain. The experiments are performed in the range of 3-6 microL/h with 3sigma detection limits determined to be 0.127 nL/s. Additionally, the RI response of the system is calibrated using temperature changes as well as glycerol solutions.

  7. Accurate measurement of streamwise vortices in low speed aerodynamic flows

    NASA Astrophysics Data System (ADS)

    Waldman, Rye M.; Kudo, Jun; Breuer, Kenneth S.

    2010-11-01

    Low Reynolds number experiments with flapping animals (such as bats and small birds) are of current interest in understanding biological flight mechanics, and due to their application to Micro Air Vehicles (MAVs) which operate in a similar parameter space. Previous PIV wake measurements have described the structures left by bats and birds, and provided insight to the time history of their aerodynamic force generation; however, these studies have faced difficulty drawing quantitative conclusions due to significant experimental challenges associated with the highly three-dimensional and unsteady nature of the flows, and the low wake velocities associated with lifting bodies that only weigh a few grams. This requires the high-speed resolution of small flow features in a large field of view using limited laser energy and finite camera resolution. Cross-stream measurements are further complicated by the high out-of-plane flow which requires thick laser sheets and short interframe times. To quantify and address these challenges we present data from a model study on the wake behind a fixed wing at conditions comparable to those found in biological flight. We present a detailed analysis of the PIV wake measurements, discuss the criteria necessary for accurate measurements, and present a new dual-plane PIV configuration to resolve these issues.

  8. Flow velocity measurement with the nonlinear acoustic wave scattering

    SciTech Connect

    Didenkulov, Igor; Pronchatov-Rubtsov, Nikolay

    2015-10-28

    A problem of noninvasive measurement of liquid flow velocity arises in many practical applications. To this end the most often approach is the use of the linear Doppler technique. The Doppler frequency shift of signal scattered from the inhomogeneities distributed in a liquid relatively to the emitted frequency is proportional to the sound frequency and velocities of inhomogeneities. In the case of very slow flow one needs to use very high frequency sound. This approach fails in media with strong sound attenuation because acoustic wave attenuation increases with frequency and there is limit in increasing sound intensity, i.e. the cavitation threshold. Another approach which is considered in this paper is based on the method using the difference frequency Doppler Effect for flows with bubbles. This method is based on simultaneous action of two high-frequency primary acoustic waves with closed frequencies on bubbles and registration of the scattered by bubbles acoustic field at the difference frequency. The use of this method is interesting since the scattered difference frequency wave has much lower attenuation in a liquid. The theoretical consideration of the method is given in the paper. The experimental examples confirming the theoretical equations, as well as the ability of the method to be applied in medical diagnostics and in technical applications on measurement of flow velocities in liquids with strong sound attenuation is described. It is shown that the Doppler spectrum form depends on bubble concentration velocity distribution in the primary acoustic beams crossing zone that allows one to measure the flow velocity distribution.

  9. 40 CFR 86.313-79 - Air flow measurement specifications; diesel engines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Air flow measurement specifications... Procedures § 86.313-79 Air flow measurement specifications; diesel engines. (a) The air flow measurement method used must have a range large enough to accurately measure the air flow over the engine...

  10. 40 CFR 86.313-79 - Air flow measurement specifications; diesel engines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Air flow measurement specifications... Procedures § 86.313-79 Air flow measurement specifications; diesel engines. (a) The air flow measurement method used must have a range large enough to accurately measure the air flow over the engine...

  11. 40 CFR 86.313-79 - Air flow measurement specifications; diesel engines.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 19 2012-07-01 2012-07-01 false Air flow measurement specifications... Procedures § 86.313-79 Air flow measurement specifications; diesel engines. (a) The air flow measurement method used must have a range large enough to accurately measure the air flow over the engine...

  12. Basic data for some recent Australian heat-flow measurements

    USGS Publications Warehouse

    Munroe, Robert J.; Sass, J.H.; Milburn, G.T.; Jaeger, J.C.; Tammemagi, H.Y.

    1975-01-01

    This report has been compiled to provide background information and detailed temperature and thermal conductivity data for the heat-flow values reported in Sass, Jaeger, and Munroe (in press). The data were collected as part of a joint heat-flow study by the Australian National University (ANU) and the U.S. Geological Survey (USGS) under the direction of J. C. Jaeger (ANU) and J. H. Sass (USGS). The format is similar to that used for basic data from United States heat-flow determinations (Sass and Munroe, 1974). Each section contains a state map showing the geographic distribution of heat-flow data followed by tables which list individual temperatures, thermal conductivities, and radiogenic heat production values. A companion volume (Bunker and others, 1975) gives details of the heat-production measurements together with individual radioelement concentrations. Localities are arranged in alphabetical order within each state. The methods and techniques of measurements have been described by Sass and others (1971a, b). Unusual methods or procedures which differ markedly from these techniques are noted and described in the comments sections of the tables.

  13. A New Differential Pressure Flow Meter for Measurement of Human Breath Flow: Simulation and Experimental Investigation

    PubMed Central

    Bridgeman, Devon; Tsow, Francis; Xian, Xiaojun; Forzani, Erica

    2016-01-01

    The development and performance characterization of a new differential pressure-based flow meter for human breath measurements is presented in this article. The device, called a “Confined Pitot Tube,” is comprised of a pipe with an elliptically shaped expansion cavity located in the pipe center, and an elliptical disk inside the expansion cavity. The elliptical disk, named Pitot Tube, is exchangeable, and has different diameters, which are smaller than the diameter of the elliptical cavity. The gap between the disk and the cavity allows the flow of human breath to pass through. The disk causes an obstruction in the flow inside the pipe, but the elliptical cavity provides an expansion for the flow to circulate around the disk, decreasing the overall flow resistance. We characterize the new sensor flow experimentally and theoretically, using Comsol Multiphysics® software with laminar and turbulent models. We also validate the sensor, using inhalation and exhalation tests and a reference method. PMID:27818521

  14. Measurements of the flow and thermal characteristics of turbulet jets in cross flow

    NASA Astrophysics Data System (ADS)

    Sherif, S. A.

    An experimental investigation of the flow, turbulence, and thermal characteristics of heated, cooled, and isothermal turbulent jets in cross flow is reported. The experiments were carried out in a water channel facility of the recirculation type. Hot or cold water was injected verically upward from a circular pipe located near the channel bottom to the cross-flowing stream in the channel. Hot and cold-film anemometers along with appropriate linearizers, bridges, filters, and probes were used. A new signal analysis method was developed for resolving the complex three-dimensional structure of the mean turbulent flow field resulting from the interaction between the free stream and the jet. A rotatable probe technique was used to measure the size components for the Reynolds stress tensor in isothermal flows of any turbulence intensity. New experssions that correct for the temperature contamination of the velocity signals in nonisothermal flows were developed for both the linearized and unlinearized anemometer responses. Mean velocity and turbulence intensity data were obtained for the isothermal jet at jet-to-free stream velocity ratios of 2, 4, and 6 both in and outside the jet plane of symmetry.

  15. Measuring Material Microstructure Under Flow Using 1-2 Plane Flow-Small Angle Neutron Scattering

    PubMed Central

    Gurnon, A. Kate; Godfrin, P. Douglas; Wagner, Norman J.; Eberle, Aaron P. R.; Butler, Paul; Porcar, Lionel

    2014-01-01

    A new small-angle neutron scattering (SANS) sample environment optimized for studying the microstructure of complex fluids under simple shear flow is presented. The SANS shear cell consists of a concentric cylinder Couette geometry that is sealed and rotating about a horizontal axis so that the vorticity direction of the flow field is aligned with the neutron beam enabling scattering from the 1-2 plane of shear (velocity-velocity gradient, respectively). This approach is an advance over previous shear cell sample environments as there is a strong coupling between the bulk rheology and microstructural features in the 1-2 plane of shear. Flow-instabilities, such as shear banding, can also be studied by spatially resolved measurements. This is accomplished in this sample environment by using a narrow aperture for the neutron beam and scanning along the velocity gradient direction. Time resolved experiments, such as flow start-ups and large amplitude oscillatory shear flow are also possible by synchronization of the shear motion and time-resolved detection of scattered neutrons. Representative results using the methods outlined here demonstrate the useful nature of spatial resolution for measuring the microstructure of a wormlike micelle solution that exhibits shear banding, a phenomenon that can only be investigated by resolving the structure along the velocity gradient direction. Finally, potential improvements to the current design are discussed along with suggestions for supplementary experiments as motivation for future experiments on a broad range of complex fluids in a variety of shear motions. PMID:24561395

  16. Measuring material microstructure under flow using 1-2 plane flow-small angle neutron scattering.

    PubMed

    Gurnon, A Kate; Godfrin, P Douglas; Wagner, Norman J; Eberle, Aaron P R; Butler, Paul; Porcar, Lionel

    2014-02-06

    A new small-angle neutron scattering (SANS) sample environment optimized for studying the microstructure of complex fluids under simple shear flow is presented. The SANS shear cell consists of a concentric cylinder Couette geometry that is sealed and rotating about a horizontal axis so that the vorticity direction of the flow field is aligned with the neutron beam enabling scattering from the 1-2 plane of shear (velocity-velocity gradient, respectively). This approach is an advance over previous shear cell sample environments as there is a strong coupling between the bulk rheology and microstructural features in the 1-2 plane of shear. Flow-instabilities, such as shear banding, can also be studied by spatially resolved measurements. This is accomplished in this sample environment by using a narrow aperture for the neutron beam and scanning along the velocity gradient direction. Time resolved experiments, such as flow start-ups and large amplitude oscillatory shear flow are also possible by synchronization of the shear motion and time-resolved detection of scattered neutrons. Representative results using the methods outlined here demonstrate the useful nature of spatial resolution for measuring the microstructure of a wormlike micelle solution that exhibits shear banding, a phenomenon that can only be investigated by resolving the structure along the velocity gradient direction. Finally, potential improvements to the current design are discussed along with suggestions for supplementary experiments as motivation for future experiments on a broad range of complex fluids in a variety of shear motions.

  17. Stochastic Measurement Models for Quantifying Lymphocyte Responses Using Flow Cytometry

    PubMed Central

    Kan, Andrey; Pavlyshyn, Damian; Markham, John F.; Dowling, Mark R.; Heinzel, Susanne; Zhou, Jie H. S.; Marchingo, Julia M.; Hodgkin, Philip D.

    2016-01-01

    Adaptive immune responses are complex dynamic processes whereby B and T cells undergo division and differentiation triggered by pathogenic stimuli. Deregulation of the response can lead to severe consequences for the host organism ranging from immune deficiencies to autoimmunity. Tracking cell division and differentiation by flow cytometry using fluorescent probes is a major method for measuring progression of lymphocyte responses, both in vitro and in vivo. In turn, mathematical modeling of cell numbers derived from such measurements has led to significant biological discoveries, and plays an increasingly important role in lymphocyte research. Fitting an appropriate parameterized model to such data is the goal of these studies but significant challenges are presented by the variability in measurements. This variation results from the sum of experimental noise and intrinsic probabilistic differences in cells and is difficult to characterize analytically. Current model fitting methods adopt different simplifying assumptions to describe the distribution of such measurements and these assumptions have not been tested directly. To help inform the choice and application of appropriate methods of model fitting to such data we studied the errors associated with flow cytometry measurements from a wide variety of experiments. We found that the mean and variance of the noise were related by a power law with an exponent between 1.3 and 1.8 for different datasets. This violated the assumptions inherent to commonly used least squares, linear variance scaling and log-transformation based methods. As a result of these findings we propose a new measurement model that we justify both theoretically, from the maximum entropy standpoint, and empirically using collected data. Our evaluation suggests that the new model can be reliably used for model fitting across a variety of conditions. Our work provides a foundation for modeling measurements in flow cytometry experiments thus

  18. Study of flow rate induced measurement error in flow-through nano-hole plasmonic sensor

    PubMed Central

    Tu, Long; Huang, Liang; Wang, Tianyi; Wang, Wenhui

    2015-01-01

    Flow-through gold film perforated with periodically arrayed sub-wavelength nano-holes can cause extraordinary optical transmission (EOT), which has recently emerged as a label-free surface plasmon resonance sensor in biochemical detection by measuring the transmission spectral shift. This paper describes a systematic study of the effect of microfluidic field on the spectrum of EOT associated with the porous gold film. To detect biochemical molecules, the sub-micron-thick film is free-standing in a microfluidic field and thus subject to hydrodynamic deformation. The film deformation alone may cause spectral shift as measurement error, which is coupled with the spectral shift as real signal associated with the molecules. However, this microfluid-induced measurement error has long been overlooked in the field and needs to be identified in order to improve the measurement accuracy. Therefore, we have conducted simulation and analytic analysis to investigate how the microfluidic flow rate affects the EOT spectrum and verified the effect through experiment with a sandwiched device combining Au/Cr/Si3N4 nano-hole film and polydimethylsiloxane microchannels. We found significant spectral blue shift associated with even small flow rates, for example, 12.60 nm for 4.2 μl/min. This measurement error corresponds to 90 times the optical resolution of the current state-of-the-art commercially available spectrometer or 8400 times the limit of detection. This really severe measurement error suggests that we should pay attention to the microfluidic parameter setting for EOT-based flow-through nano-hole sensors and adopt right scheme to improve the measurement accuracy. PMID:26649131

  19. Flow cytometric measurement of total DNA and incorporated halodeoxyuridine

    DOEpatents

    Dolbeare, F.A.; Gray, J.W.

    1983-10-18

    A method for the simultaneous flow cylometric measurement of total cellular DNA content and of the uptake of DNA precursors as a measure of DNA synthesis during various phases of the cell cycle in normal and malignant cells in vitro and in vivo is described. The method comprises reacting cells with labelled halodeoxyuridine (HdU), partially denaturing cellular DNA, adding to the reaction medium monoclonal antibodies (mabs) reactive with HdU, reacting the bound mabs with a second labelled antibody, incubating the mixture with a DNA stain, and measuring simultaneously the intensity of the DNA stain as a measure of the total cellular DNA and the HdU incorporated as a measure of DNA synthesis. (ACR)

  20. Flow cytometric measurement of total DNA and incorporated halodeoxyuridine

    DOEpatents

    Dolbeare, Frank A.; Gray, Joe W.

    1988-01-01

    A method for the simultaneous flow cytometric measurement of the total DNA content and the level of DNA synthesis in normal and malignant cells is disclosed. The sensitivity of the method allows a study of cell cycle traverse rates for large scale cell populations as well as single cell measurements. A DNA stain such as propidium iodide or Hoechst 33258 is used as the probe for the measurement of total DNA content and a monoclonal antibody reactive with a DNA precursor such as halodeoxy-uridine (HdU), more specifically bromodeoxyuridine (BrdU) is used as a probe for the measurement of HdU or BrdU uptake by the cells as a measure of DNA synthesis.

  1. Spectroscopy Measurements on Ablation Testing in High Enthalpy Plasma Flows

    DTIC Science & Technology

    2010-11-01

    stagnation point, are located on the ablative material sample. 3.5 InfraRed THERMOGRAPHY Surface temperature measurement is a topic of great concern...high temperature material at two different narrow wavelengths. The temperature is calculated by building the ratio of the radiation intensities. The...this work is to develop the capability of testing and characterization of ablative materials exposed to high enthalpy plasma flows including both

  2. Ultrasonic Doppler measurement of renal artery blood flow

    NASA Technical Reports Server (NTRS)

    Freund, W. R.; Meindl, J. D.

    1975-01-01

    An extensive evaluation of the practical and theoretical limitations encountered in the use of totally implantable CW Doppler flowmeters is provided. Theoretical analyses, computer models, in-vitro and in-vivo calibration studies describe the sources and magnitudes of potential errors in the measurement of blood flow through the renal artery, as well as larger vessels in the circulatory system. The evaluation of new flowmeter/transducer systems and their use in physiological investigations is reported.

  3. Laser Velocimetry Measurements of Oscillating Airfoil Dynamic Stall Flow Field

    DTIC Science & Technology

    1991-06-01

    Velocimetry Measurements of Oscillating Airfoil Dynamic Stall Flow Field By M.S.Chandrasekharal Navy-NASA Joint Institute of Aeronautics and Fluid Mechanics ...tunnel of the Fluid Mechanics Laboratory(FML) angle information. The other could be used for the at NASA Ames Research Center (ARC). It is one of...were on throat is always kept choked so that no disturbances a different traverse mechanism , but this was driven as can propagate upstream into the

  4. Modeling and Measurement of Turbulent Swirling Flows Through Abrupt Expansions.

    DTIC Science & Technology

    1987-03-01

    Measurements, B22. Touloukian , Y.S. (editor), 1967, Tbermophysical Properties of High Temperature Solid Mfaterials, Vol. 3: Ferrous Alloys ...Stanford University, 1978. School of Mechanical Engrg, Purdue University, 30. J. K. Eaton and J. P. Johnston, Turbulent Flow West Lafayette. IN, July 1983...from 12 R, where a linear curve fit of the temperature dependent resistivity of the stainless steel "e ( Touloukian , 1967) test section was used. Heat

  5. Whole Field Measurements of Vorticity in Turbulent and Unsteady Flows

    DTIC Science & Technology

    1988-10-11

    shown in Fig. 2. It was fabricated by component of velocity in flows with predominately one individually fixing Aluminum coated mirrors (with the...3. EXPERIMENTAL RESULTS Two experiments were performed to demonstrate the technique. Both used deodorized kerosene with 10 ppm of the photochromtic...the blaze angle, and the grating step width and spacing. It was fabricated by individually fixing 2.1. Review of the measurement technique aluminum

  6. Velocity Measurements of Thermoelectric Driven Flowing Liquid Lithium

    NASA Astrophysics Data System (ADS)

    Szott, Matthew; Xu, Wenyu; Fiflis, Peter; Haehnlein, Ian; Kapat, Aveek; Kalathiparambil, Kishor; Ruzic, David N.

    2014-10-01

    Liquid lithium has garnered additional attention as a PFC due to its several advantages over solid PFCs, including reduced erosion and thermal fatigue, increased heat transfer, higher device lifetime, and enhanced plasma performance due to the establishment of low recycling regimes at the wall. The Lithium Metal Infused Trenches concept (LiMIT) has demonstrated thermoelectric magnetohydrodynamic flow of liquid lithium through horizontal open-faced metal trenches with measured velocities varying from 3.7+/-0.5 cm/s in the 1.76 T field of HT-7 to 22+/-3 cm/s in the SLiDE facility at UIUC at 0.059 T. To demonstrate the versatility of the concept, a new LiMIT design using narrower trenches shows steady state, thermoelectric-driven flow at an arbitrary angle from horizontal. Velocity characteristics are measured and discussed. Based on this LiMIT concept, a new limiter design has been developed to be tested on the mid-plane of the EAST plasma. Preliminary modelling suggests lithium flow of 6 cm/s in this device. Additionally, recent testing at the Magnum-PSI facility has given encouraging results, and velocity measurements in relation to magnetic field strength and plasma flux are also presented.

  7. Measuring and Optimizing flows in the Madison Dynamo Experiment

    NASA Astrophysics Data System (ADS)

    Taylor, N. Z.; Clark, M.; Forest, C. B.; Kaplan, E. J.; Nornberg, M. D.; Rasmus, A. M.; Rahbarnia, K.

    2012-10-01

    In the Madison Dynamo Experiment, two counter-rotating impellers drive a turbulent flow of liquid sodium in a one meter-diameter sphere. One of the goals of the experiment is to observe a magnetic field grow at the expense of kinetic energy in the flow. The enormous Reynolds number of the experiment and its two vortex geometry leads to a large turbulent EMF. This poster presents results from the MDE after several upgrades were made. First, an equatorial baffle was installed to stabilize the position of the shear layer between the two counterrotating hemispheres. This reduced the scale of the largest eddies in the experiment, lowering the effective resistivity due to turbulence. Next, a probe was used to measure both the fluctuating velocity and magnetic fields, enabling a direct measurement of the turbulent EMF. This EMF is anti-parallel to the mean current, consistent with an enhanced resistivity predicted by mean field theory. Finally, vanes with adjustable orientation were installed on the vessel wall, allowing the pitch of the helical flow to be altered. Computational fluid dynamics simulations and inversion of the measured induced magnetic field are used to determine the optimum angle of these vanes to minimize the critical velocity at which the dynamo onset occurs.

  8. Flow Visualization of Low Prandtl Number Fluids using Electrochemical Measurements

    NASA Technical Reports Server (NTRS)

    Crunkleton, D.; Anderson, T.; Narayanan, R.; Labrosse, G.

    2003-01-01

    It is well established that residual flows exist in contained liquid metal processes. In 1-g processing, buoyancy forces often drive these flows and their magnitudes can be substantial. It is also known that residual flows can exist during microgravity processing, and although greatly reduced in magnitude, they can influence the properties of the processed materials. Unfortunately, there are very few techniques to visualize flows in opaque, high temperature liquid metals, and those available are not easily adapted to flight investigation. In this study, a novel technique is developed that uses liquid tin as the model fluid and solid-state electrochemical cells constructed from Yttria-Stabilized Zirconia (YSZ) to establish and measure dissolved oxygen boundary conditions. The melt serves as a common electrode for each of the electrochemical cells in this design, while independent reference electrodes are maintained at the outside surfaces of the electrolyte. By constructing isolated electrochemical cells at various locations along the container walls, oxygen is introduced or extracted by imposing a known electrical potential or passing a given current between the melt and the reference electrode. This programmed titration then establishes a known oxygen concentration boundary condition at the selected electrolyte-melt interface. Using the other cells, the concentration of oxygen at the electrolyte-melt interface is also monitored by measuring the open-circuit potentials developed between the melt and reference electrodes. Thus the electrochemical cells serve to both establish boundary conditions for the passive tracer and sense its path. Rayleigh-Benard convection was used to validate the electrochemical approach to flow visualization. Thus, a numerical characterization of the second critical Rayleigh numbers in liquid tin was conducted for a variety of Cartesian aspect ratios. The extremely low Prandtl number of tin represents the lowest value studied numerically

  9. Quantitative measurements of cerebral blood flow in volume imaging PET scanners

    SciTech Connect

    Smith, R.J.; Shao, L.; Freifelder, R.; Karp, J.S.; Ragland, J.D.

    1995-08-01

    Quantitative measurements of Cerebral Blood Flow (CBF) are performed in a volume imaging PET Scanner by means of moderate activity infusions. In equilibrium infusions, activations are measured by scanning over 10 minutes with 16 minute activations. Typical measured whole brain CBF values are 37{+-}8 ml/min/100g, close to the value of 42 ml/min/100g reported by other groups using this method. For ramped infusions, scanning over 4 minutes with 5 minute activations results in whole brain CBFs of 49 {+-} 9 ml/min/100g, close to the Kety and Schmidt value of 50 ml/min/100g. Both equilibrium and ramped infusion methods have been used to study face and word memory in human subjects. Both methods were able to detect significant activations in regions implicated in human memory. The authors conclude that precise quantitation of regional CBF is achieved using both methods, and that ramped infusions also provide accurate measures of CBF. In addition a simplified protocol for ramped infusion studies has been developed. In this method the whole brain tissue time activity curve generated from dynamic scanning is replaced by an appropriately scaled camera coincidence countrate curve. The resulting whole brain CBF values are only 7% different from the dynamic scan and fit results. Regional CBFs (rCBF) may then be generated from the summed image (4.25 minutes) using a count density vs flow lookup table.

  10. Verifying a Simplified Fuel Oil Flow Field Measurement Protocol

    SciTech Connect

    Henderson, H.; Dentz, J.; Doty, C.

    2013-07-01

    The Better Buildings program is a U.S. Department of Energy program funding energy efficiency retrofits in buildings nationwide. The program is in need of an inexpensive method for measuring fuel oil consumption that can be used in evaluating the impact that retrofits have in existing properties with oil heat. This project developed and verified a fuel oil flow field measurement protocol that is cost effective and can be performed with little training for use by the Better Buildings program as well as other programs and researchers.

  11. Measurement of electroosmotic flow in capillary and microchip electrophoresis.

    PubMed

    Wang, Wei; Zhou, Fang; Zhao, Liang; Zhang, Jian-Rong; Zhu, Jun-Jie

    2007-11-02

    Microfluidics is the science and technology of systems that process or manipulate small amounts of fluids, using channels with dimensions of tens of micrometers. Electroosmotic flow (EOF) is an important characteristic of fluids in microchannels. In this paper, EOF generation, effects on separation and definition of EOF are introduced. And EOF measurement methods on capillary electrophoresis (CE) and microchip CE are systematically reviewed based on detection principle, hallmarks of EOF measurement methods are presented, the devices and signals are also schematically described. This paper offers researchers a guidance to obtain an estimate of EOF mobility in capillary and microchip electrophoresis.

  12. Gas and liquid measurements in air-water bubbly flows

    SciTech Connect

    Zhou, X.; Doup, B.; Sun, X.

    2012-07-01

    Local measurements of gas- and liquid-phase flow parameters are conducted in an air-water two-phase flow loop. The test section is a vertical pipe with an inner diameter of 50 mm and a height of 3.2 m. The measurements are performed at z/D = 10. The gas-phase measurements are performed using a four-sensor conductivity probe. The data taken from this probe are processed using a signal processing program to yield radial profiles of the void fraction, bubble velocity, and interfacial area concentration. The velocity measurements of the liquid-phase are performed using a state-of-the-art Particle Image Velocimetry (PIV) system. The raw PIV images are acquired using fluorescent particles and an optical filtration device. Image processing is used to remove noise in the raw PIV images. The statistical cross correlation is introduced to determine the axial velocity field and turbulence intensity of the liquid-phase. Measurements are currently being performed at z/D = 32 to provide a more complete data set. These data can be used for computational fluid dynamic model development and validation. (authors)

  13. Laser velocimeter measurements of multiphase flow of solids

    SciTech Connect

    Kadambi, J.R.; Chen, R.C.; Bhunia, S.

    1989-01-01

    A unique refractive index matched facility for studying solid-liquid multiphase flow has been developed. The refractive index matching of the solid and the liquid allows the use of non-intrusive Laser Doppler Velocimetry (LDV) to measure the solid and the liquid velocities. These measurements will be useful in developing a better understanding of solid-liquid flows, especially solid-liquid and solid-solid interactions. Silica gel and 50% sodium iodide solution in water (refractive index {approx}1.443) are used as the refractive index matched solid and liquid respectively. A two color back scatter mode LDV is used for making velocity measurements. Tests were conducted in solid-liquid slurries with volumetric solid concentration levels of 5% and 15% in the Reynolds number (Re) range of 400 to 9200. Silica gel particles of mean diameter 40 microns were used. Measurements included mapping of the solid and liquid velocities and obtaining the pressure drop data. Signal processing technique utilizing histogram of velocity measurements made at a point and signal amplitude discrimination was successfully used for differentiating between solid and liquid velocities. 34 refs., 61 figs., 5 tabs.

  14. A robust thermal microstructure for mass flow rate measurement in steady and unsteady flows

    NASA Astrophysics Data System (ADS)

    Viard, R.; Talbi, A.; Merlen, A.; Pernod, P.; Frankiewicz, C.; Gerbedoen, J.-C.; Preobrazhensky, V.

    2013-06-01

    A silicon micro-machined thermal gas flow sensor operating in anemometric mode has been designed, fabricated and investigated for continuous and pulsatile flows. The sensor is specifically designed to achieve high sensitivity, fast response time and high robustness. It is composed of four metallic resistors interconnected to form a Wheatstone bridge. Two of them act simultaneously as the heating and sensing elements and the two others are used as a temperature reference. The heating element consists of a metallic wire of platinum Pt (2 µm width, 2 mm length) maintained on each lateral side by periodic silicon oxide SiO2 micro-bridges. Finite element simulations show that this structure achieves a fast thermal response time of 200 µs in constant current operating mode and a coefficient of temperature rise close to 25 °C/120 µW based on bulk electrical resistivity and when the Pt wire and SiO2 thicknesses are close to 100 nm and 500 nm, respectively. This design allows the fabrication of a robust thermal flow sensor with heating elements as long as possible, which enables accurate measurements with high signal to noise ratio. The sensor is then characterised experimentally; its electrical and thermal properties are obtained in the absence of fluid flow. These results confirm the effectiveness of the thermal insulation as predicted by the simulations. In a second step, the fluidic characterizations are reported and discussed for both continuous and pulsatile flows. In continuous mode, the sensor response was studied for gas flow rate ranging from 0 L min-1 to 10 L min-1. In pulsatile mode, the sensor is integrated inside a channel of a micro-valve actuated at 200 Hz. The measurements are compared with those obtained by a classical commercial hot wire.

  15. Acoustic measurement of the Deepwater Horizon Macondo well flow rate

    PubMed Central

    Camilli, Richard; Di Iorio, Daniela; Bowen, Andrew; Reddy, Christopher M.; Techet, Alexandra H.; Yoerger, Dana R.; Whitcomb, Louis L.; Seewald, Jeffrey S.; Sylva, Sean P.; Fenwick, Judith

    2012-01-01

    On May 31, 2010, a direct acoustic measurement method was used to quantify fluid leakage rate from the Deepwater Horizon Macondo well prior to removal of its broken riser. This method utilized an acoustic imaging sonar and acoustic Doppler sonar operating onboard a remotely operated vehicle for noncontact measurement of flow cross-section and velocity from the well’s two leak sites. Over 2,500 sonar cross-sections and over 85,000 Doppler velocity measurements were recorded during the acquisition process. These data were then applied to turbulent jet and plume flow models to account for entrained water and calculate a combined hydrocarbon flow rate from the two leak sites at seafloor conditions. Based on the chemical composition of end-member samples collected from within the well, this bulk volumetric rate was then normalized to account for contributions from gases and condensates at initial leak source conditions. Results from this investigation indicate that on May 31, 2010, the well’s oil flow rate was approximately 0.10 ± 0.017 m3 s-1 at seafloor conditions, or approximately 85 ± 15 kg s-1 (7.4 ± 1.3 Gg d-1), equivalent to approximately 57,000 ± 9,800 barrels of oil per day at surface conditions. End-member chemical composition indicates that this oil release rate was accompanied by approximately an additional 24 ± 4.2 kg s-1 (2.1 ± 0.37 Gg d-1) of natural gas (methane through pentanes), yielding a total hydrocarbon release rate of 110 ± 19 kg s-1 (9.5 ± 1.6 Gg d-1). PMID:21903931

  16. Acoustic measurement of the Deepwater Horizon Macondo well flow rate.

    PubMed

    Camilli, Richard; Di Iorio, Daniela; Bowen, Andrew; Reddy, Christopher M; Techet, Alexandra H; Yoerger, Dana R; Whitcomb, Louis L; Seewald, Jeffrey S; Sylva, Sean P; Fenwick, Judith

    2012-12-11

    On May 31, 2010, a direct acoustic measurement method was used to quantify fluid leakage rate from the Deepwater Horizon Macondo well prior to removal of its broken riser. This method utilized an acoustic imaging sonar and acoustic Doppler sonar operating onboard a remotely operated vehicle for noncontact measurement of flow cross-section and velocity from the well's two leak sites. Over 2,500 sonar cross-sections and over 85,000 Doppler velocity measurements were recorded during the acquisition process. These data were then applied to turbulent jet and plume flow models to account for entrained water and calculate a combined hydrocarbon flow rate from the two leak sites at seafloor conditions. Based on the chemical composition of end-member samples collected from within the well, this bulk volumetric rate was then normalized to account for contributions from gases and condensates at initial leak source conditions. Results from this investigation indicate that on May 31, 2010, the well's oil flow rate was approximately 0.10 ± 0.017 m(3) s(-1) at seafloor conditions, or approximately 85 ± 15 kg s(-1) (7.4 ± 1.3 Gg d(-1)), equivalent to approximately 57,000 ± 9,800 barrels of oil per day at surface conditions. End-member chemical composition indicates that this oil release rate was accompanied by approximately an additional 24 ± 4.2 kg s(-1) (2.1 ± 0.37 Gg d(-1)) of natural gas (methane through pentanes), yielding a total hydrocarbon release rate of 110 ± 19 kg s(-1) (9.5 ± 1.6 Gg d(-1)).

  17. Fluid flow measurements by means of vibration monitoring

    NASA Astrophysics Data System (ADS)

    Campagna, Mauro M.; Dinardo, Giuseppe; Fabbiano, Laura; Vacca, Gaetano

    2015-11-01

    The achievement of accurate fluid flow measurements is fundamental whenever the control and the monitoring of certain physical quantities governing an industrial process are required. In that case, non-intrusive devices are preferable, but these are often more sophisticated and expensive than those which are more common (such as nozzles, diaphrams, Coriolis flowmeters and so on). In this paper, a novel, non-intrusive, simple and inexpensive methodology is presented to measure the fluid flow rate (in a turbulent regime) whose physical principle is based on the acquisition of transversal vibrational signals induced by the fluid itself onto the pipe walls it is flowing through. Such a principle of operation would permit the use of micro-accelerometers capable of acquiring and transmitting the signals, even by means of wireless technology, to a control room for the monitoring of the process under control. A possible application (whose feasibility will be investigated by the authors in a further study) of this introduced technology is related to the employment of a net of micro-accelerometers to be installed on pipeline networks of aqueducts. This apparatus could lead to the faster and easier detection and location of possible leaks of fluid affecting the pipeline network with more affordable costs. The authors, who have previously proven the linear dependency of the acceleration harmonics amplitude on the flow rate, here discuss an experimental analysis of this functional relation with the variation in the physical properties of the pipe in terms of its diameter and constituent material, to find the eventual limits to the practical application of the measurement methodology.

  18. Sap flow measurements to determine the transpiration of facade greenings

    NASA Astrophysics Data System (ADS)

    Hölscher, Marie-Therese; Nehls, Thomas; Wessolek, Gerd

    2014-05-01

    Facade greening is expected to make a major contribution to the mitigation of the urban heat-island effect through transpiration cooling, thermal insulation and shading of vertical built structures. However, no studies are available on water demand and the transpiration of urban vertical green. Such knowledge is needed as the plants must be sufficiently watered, otherwise the posited positive effects of vertical green can turn into disadvantages when compared to a white wall. Within the framework of the German Research Group DFG FOR 1736 "Urban Climate and Heat Stress" this study aims to test the practicability of the sap flow technique for transpiration measurements of climbing plants and to obtain potential transpiration rates for the most commonly used species. Using sap flow measurements we determined the transpiration of Fallopia baldschuanica, Parthenocissus tricuspidata and Hedera helix in pot experiments (about 1 m high) during the hot summer period from August 17th to August 30th 2012 under indoor conditions. Sap flow measurements corresponded well to simultaneous weight measurement on a daily base (factor 1.19). Fallopia baldschuanica has the highest daily transpiration rate based on leaf area (1.6 mm d-1) and per base area (5.0 mm d-1). Parthenocissus tricuspidata and Hedera helix show transpiration rates of 3.5 and 0.4 mm d-1 (per base area). Through water shortage, transpiration strongly decreased and leaf temperature measured by infrared thermography increased by 1 K compared to a well watered plant. We transferred the technique to outdoor conditions and will present first results for facade greenings in the inner-city of Berlin for the hottest period in summer 2013.

  19. Contactless impedance sensors and their application to flow measurements.

    PubMed

    Opekar, František; Tůma, Petr; Stulík, Karel

    2013-02-27

    The paper provides a critical discussion of the present state of the theory of high-frequency impedance sensors (now mostly called contactless impedance or conductivity sensors), the principal approaches employed in designing impedance flow-through cells and their operational parameters. In addition to characterization of traditional types of impedance sensors, the article is concerned with the use of less common sensors, such as cells with wire electrodes or planar cells. There is a detailed discussion of the effect of the individual operational parameters (width and shape of the electrodes, detection gap, frequency and amplitude of the input signal) on the response of the detector. The most important problems to be resolved in coupling these devices with flow-through measurements in the liquid phase are also discussed. Examples are given of cell designs for continuous flow and flow-injection analyses and of detection systems for miniaturized liquid chromatography and capillary electrophoresis. New directions for the use of these sensors in molecular biology and chemical reactors and some directions for future development are outlined.

  20. Mass flow and its pulsation measurements in supersonic wing wake

    NASA Astrophysics Data System (ADS)

    Shmakov, A. S.; Shevchenko, A. M.; Yatskikh, A. A.; Yermolaev, Yu. G.

    2016-10-01

    The results of experimental study of the flow in the wing wake are presented. Experiments were carried out in supersonic wind tunnel T-325 of ITAM SB RAS. Rectangle half-wing with sharp edges with a chord length of 30 mm and semispan of 95 mm was used to generate vortex wake. Experimental data were obtained in the cross section located 6 chord length downstream of the trailing edge at Mach numbers of 2.5 and 4 and at wing angles of attack of 4 and 10 degrees. Constant temperature hot-wire anemometer was used to measure disturbances in supersonic flow. Hot-wire was made of a tungsten wire with a diameter of 10 μm and length of 1.5 mm. Shlieren flow visualization were performed. As a result, the position and size of the vortex core in the wake of a rectangular wing were determined. For the first time experimental data on the mass flow distribution and its pulsations in the supersonic longitudinal vortex were obtained.

  1. Influence of chronic moderate sleep restriction and exercise training on anxiety, spatial memory, and associated neurobiological measures in mice.

    PubMed

    Zielinski, Mark R; Davis, J Mark; Fadel, James R; Youngstedt, Shawn D

    2013-08-01

    Sleep deprivation can have deleterious effects on cognitive function and mental health. Moderate exercise training has myriad beneficial effects on cognition and mental health. However, physiological and behavioral effects of chronic moderate sleep restriction and its interaction with common activities, such as moderate exercise training, have received little investigation. The aims of this study were to examine the effects of chronic moderate sleep restriction and moderate exercise training on anxiety-related behavior, spatial memory, and neurobiological correlates in mice. Male mice were randomized to one of four 11-week treatments in a 2 [sleep restriction (∼4h loss/day) vs. ad libitum sleep] × 2 [exercise (1h/day/6 d/wk) vs. sedentary activity] experimental design. Anxiety-related behavior was assessed with the elevated-plus maze, and spatial learning and memory were assessed with the Morris water maze. Chronic moderate sleep restriction did not alter anxiety-related behavior, but exercise training significantly attenuated anxiety-related behavior. Spatial learning and recall, hippocampal cell activity (i.e., number of c-Fos positive cells), and brain derived neurotrophic factor were significantly lower after chronic moderate sleep restriction, but higher after exercise training. Further, the benefit of exercise training for some memory variables was evident under normal sleep, but not chronic moderate sleep restriction conditions. These data indicate clear detrimental effects of chronic moderate sleep restriction on spatial memory and that the benefits of exercise training were impaired after chronic moderate sleep restriction.

  2. Choice of boundary condition for lattice-Boltzmann simulation of moderate-Reynolds-number flow in complex domains.

    PubMed

    Nash, Rupert W; Carver, Hywel B; Bernabeu, Miguel O; Hetherington, James; Groen, Derek; Krüger, Timm; Coveney, Peter V

    2014-02-01

    Modeling blood flow in larger vessels using lattice-Boltzmann methods comes with a challenging set of constraints: a complex geometry with walls and inlets and outlets at arbitrary orientations with respect to the lattice, intermediate Reynolds (Re) number, and unsteady flow. Simple bounce-back is one of the most commonly used, simplest, and most computationally efficient boundary conditions, but many others have been proposed. We implement three other methods applicable to complex geometries [Guo, Zheng, and Shi, Phys. Fluids 14, 2007 (2002); Bouzidi, Firdaouss, and Lallemand, Phys. Fluids 13, 3452 (2001); Junk and Yang, Phys. Rev. E 72, 066701 (2005)] in our open-source application hemelb. We use these to simulate Poiseuille and Womersley flows in a cylindrical pipe with an arbitrary orientation at physiologically relevant Re number (1-300) and Womersley (4-12) numbers and steady flow in a curved pipe at relevant Dean number (100-200) and compare the accuracy to analytical solutions. We find that both the Bouzidi-Firdaouss-Lallemand (BFL) and Guo-Zheng-Shi (GZS) methods give second-order convergence in space while simple bounce-back degrades to first order. The BFL method appears to perform better than GZS in unsteady flows and is significantly less computationally expensive. The Junk-Yang method shows poor stability at larger Re number and so cannot be recommended here. The choice of collision operator (lattice Bhatnagar-Gross-Krook vs multiple relaxation time) and velocity set (D3Q15 vs D3Q19 vs D3Q27) does not significantly affect the accuracy in the problems studied.

  3. Measurement of flow diverter hydraulic resistance to model flow modification in and around intracranial aneurysms.

    PubMed

    Ugron, Adám; Szikora, István; Paál, György

    2014-06-01

    Flow diverters (FDs) have been successfully applied in the recent decade to the treatment of intracranial aneurysms by impairing the communication between the flows in the parent artery and the aneurysm and, thus, the blood within the aneurysm sac. It would be desirable to have a simple and accurate computational method to follow the changes in the peri- and intraaneurysmal flow caused by the presence of FDs. The detailed flow simulation around the intricate wire structure of the FDs has three disadvantages: need for high amount of computational resources and highly skilled professionals to prepare the computational grid, and also the lack of validation that makes the invested effort questionable. In this paper, we propose a porous layer method to model the hydraulic resistance (HR) of one or several layers of the FDs. The basis of this proposal is twofold: first, from an application point of view, the only interesting parameter regarding the function of the FD is its HR; second, we have developed a method to measure the HR with a simple apparatus. We present the results of these measurements and demonstrate their utility in numerical simulations of patient-specific aneurysm simulations.

  4. Measurement of flow diverter hydraulic resistance to model flow modification in and around intracranial aneurysms

    PubMed Central

    Szikora, István; Paál, György

    2014-01-01

    Flow diverters (FDs) have been successfully applied in the recent decade to the treatment of intracranial aneurysms by impairing the communication between the flows in the parent artery and the aneurysm and, thus, the blood within the aneurysm sac. It would be desirable to have a simple and accurate computational method to follow the changes in the peri- and intraaneurysmal flow caused by the presence of FDs. The detailed flow simulation around the intricate wire structure of the FDs has three disadvantages: need for high amount of computational resources and highly skilled professionals to prepare the computational grid, and also the lack of validation that makes the invested effort questionable. In this paper, we propose a porous layer method to model the hydraulic resistance (HR) of one or several layers of the FDs. The basis of this proposal is twofold: first, from an application point of view, the only interesting parameter regarding the function of the FD is its HR; second, we have developed a method to measure the HR with a simple apparatus. We present the results of these measurements and demonstrate their utility in numerical simulations of patient-specific aneurysm simulations. PMID:24936307

  5. Theoretical model of blood flow measurement by diffuse correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Sakadžić, Sava; Boas, David A.; Carp, Stefan

    2017-02-01

    Diffuse correlation spectroscopy (DCS) is a noninvasive method to quantify tissue perfusion from measurements of the intensity temporal autocorrelation function of diffusely scattered light. However, DCS autocorrelation function measurements in tissue better match theoretical predictions based on the diffusive motion of the scatterers than those based on a model where the advective nature of blood flow dominates the stochastic properties of the scattered light. We have recently shown using Monte Carlo (MC) simulations and assuming a simplistic vascular geometry and laminar flow profile that the diffusive nature of the DCS autocorrelation function decay is likely a result of the shear-induced diffusion of the red blood cells. Here, we provide theoretical derivations supporting and generalizing the previous MC results. Based on the theory of diffusing-wave spectroscopy, we derive an expression for the autocorrelation function along the photon path through a vessel that takes into account both diffusive and advective scatterer motion, and we provide the solution for the DCS autocorrelation function in a semi-infinite geometry. We also derive the correlation diffusion and correlation transfer equation, which can be applied for an arbitrary sample geometry. Further, we propose a method to take into account realistic vascular morphology and flow profile.

  6. Field measurements of boundary-layer flows in ventilated rooms

    SciTech Connect

    Zhang, J.S.; Shaw, C.Y.; MacDonald, R.A.; Nguyen-Thi, L.C.; Kerr, G.

    1995-12-31

    Profiles of air velocity and turbulent kinetic energy near the surfaces of walls, ceilings, floors, and furnishings were measured under field conditions for four space layouts of an office building: a partitioned office room, a single office room, a small conference room, and a computer room. Three types of flows near the surfaces were identified based on the measured data: (1) near-stagnant flow that had mean velocities and turbulent kinetic energies of less than 0.05 {+-} 0.025 m/s (10 {+-} 5 fpm) and 0.001 {+-} 0.001 (m/s){sup 2} (38.75 {+-} 38.75 (fpm){sup 2}), respectively; (2) weak turbulence flow that had mean velocities and turbulent kinetic energies from 0.05 {+-} 0.025 to 0.25 {+-} 0.05 m/s (10 {+-} 5 to 50 {+-} 10 fpm) and from 0.001 {+-} 0.001 to 0.01 {+-} 0.002 (m/s){sup 2} (38.75 {+-} 38.75 to 387.5 {+-} 77.5 [fpm]{sup 2}), respectively. The results are useful for establishing realistic airflow conditions in testing and modeling contaminant emission from building materials and indoor furnishings.

  7. Alkaline unwinding flow cytometry assay to measure nucleotide excision repair.

    PubMed

    Thyagarajan, Bharat; Anderson, Kristin E; Lessard, Christopher J; Veltri, Gregory; Jacobs, David R; Folsom, Aaron R; Gross, Myron D

    2007-03-01

    Nucleotide excision repair (NER), one of the DNA repair pathways, is the primary mechanism for repair of bulky adducts caused by physical and chemical agents, such as UV radiation, cisplatin and 4-nitroquinolones. Variations in DNA repair may be a significant risk factor for several cancers, but its measurement in epidemiological studies has been hindered by the high variability, complexity and laborious nature of currently available assays. An alkaline unwinding flow cytometric assay using UV-C radiation as a DNA-damaging agent was adapted for measurement of NER-mediated breaks. This assay was based on the principle of alkaline unwinding of strand breaks in double-stranded DNA to yield single-stranded DNA with the number of strand breaks being proportional to the amount of DNA damage. This assay measured 50,000 events per sample with several samples being analyzed per specimen, thereby providing very reliable measurements, which can be performed on a large-scale basis. Using area under the curve (AUC) to quantitate amount of NER-mediated breaks, this assay was able to detect increased NER-mediated breaks with increasing doses of UV-C radiation. The assay detected NER-mediated breaks in lymphocytes from normal donors and not in xeroderma pigmentosum lymphoblastoid cell lines indicating specificity for the detection of NER-mediated breaks. The assay measured NER-mediated breaks within G(1), S and G(2)/M phases of the cell cycle; thereby decreasing variability in measurements of NER-mediated breaks due to differences in cell cycle phases. Intraindividual variability for AUC after 120 min of repair was 15% with interindividual variability being approximately 43% for cells in the G(1) phase, indicating substantial between-subject variation and relatively low within-subject variation. Thus, the alkaline unwinding flow cytometry-based assay provides a high-throughput method for the specific measurement of NER-mediated breaks in lymphocytes.

  8. Pressure Gradient Estimation Based on Ultrasonic Blood Flow Measurement

    NASA Astrophysics Data System (ADS)

    Nitta, Naotaka; Homma, Kazuhiro; Shiina, Tsuyoshi

    2006-05-01

    Mechanical load to the blood vessel wall, such as shear stress and pressure, which occurs in blood flow dynamics, contribute greatly to plaque rupture in arteriosclerosis and to biochemical activation of endothelial cells. Therefore, noninvasive estimations of these mechanical loads are able to provide useful information for the prevention of vascular diseases. Although the pressure is the dominant component of mechanical load, for practical purposes, the pressure gradient is also often important. So far, we have investigated the estimation of the kinematic viscosity coefficient using a combination of the Navier-Stokes equations and ultrasonic velocity measurement. In this paper, a method for pressure gradient estimation using the estimated kinematic viscosity coefficient is proposed. The validity of the proposed method was investigated on the basis of the analysis with the data obtained by computer simulation and a flow phantom experiment. These results revealed that the proposed method can provide a valid estimation of the pressure gradient.

  9. Two-phase flow cell for chemiluminescence and bioluminescence measurements

    SciTech Connect

    Mullin, J.L.; Seitz, W.R.

    1984-01-01

    A new approach to two-phase CL (chemiluminescence) measurements is reported. A magnetically stirred reagent phase is separated from the analyte phase by a dialysis membrane so that only smaller molecules can go from one phase to the other. The system is designed so that the analyte phase flows through a spiral groove on an aluminum block that is flush against the dialysis membrane. As solution flows through the spiral grove, analyte diffuses into the reagent phase where it reacts to produce light. A simple model is developed to predict how this system will behave. Experimentally, the system is evaluated by using the luminol reaction catalyzed by peroxidase, the firefly reaction, and the bacterial bioluminescence reaction. 10 references, 4 tables, 6 figures.

  10. Using Flow Cytometry to Measure Phagocytic Uptake in Earthworms†

    PubMed Central

    Fuller-Espie, Sheryl L.

    2010-01-01

    This laboratory module familiarizes students with flow cytometry while acquiring quantitative reasoning skills during data analysis. Leukocytes, also known as coelomocytes (including hyaline and granular amoebocytes, and chloragocytes), from Eisenia hortensis (earthworms) are isolated from the coelomic cavity and used for phagocytosis of fluorescent Escherichia coli. Students learn how to set up in vitro cellular assays and become familiar with theoretical principles of flow cytometry. Histograms based on fluorescence and scatter properties combined with gating options permit students to restrict their analyses to particular subsets of coelomocytes when measuring phagocytosis, a fundamentally important innate immune mechanism used in earthworms. Statistical analysis of data is included in laboratory reports which serve as the primary assessment instrument. PMID:23653715

  11. Field Measurements of the 1983 Royal Gardens Lava Flows, Kilauea Volcano, and 1984 Mauna Loa Lava Flow, Hawaii

    NASA Technical Reports Server (NTRS)

    Fink, J.; Zimbelman, J.

    1985-01-01

    Theoretical models used in the remote determination of lava flow rheology and compositions rely on estimates of such geometric and flow parameters as volume flow rates, levee heights, and channel dimensions, as well as morphologic and structural patterns on the flow surfaces. Quantitative measures of these variables are difficult to obtain, even under optimum conditions. Detailed topographic profiles across several Hawaiian lava flows that were carefully monitored by the U.S. Geological Survey during their emplacement in 1983 were surveyed in order to test various flow emplacement models. Twenty two accurate channel cross sections were constructed by combining these profiles with digitized pre-flow topographic measurements. Levee heights, shear zone widths, and flow depths could then be read directly from the cross sections and input into the models. The profiles were also compared with ones constructed for some Martian lava flows.

  12. Laser Doppler flowmetry to measure changes in cerebral blood flow.

    PubMed

    Sutherland, Brad A; Rabie, Tamer; Buchan, Alastair M

    2014-01-01

    Laser Doppler flowmetry (LDF) is a method by which relative cerebral blood flow (CBF) of the cortex can be measured. Although the method is easy to employ, LDF only measures relative CBF, while absolute CBF cannot be quantified. LDF is useful for investigating CBF changes in a number of different applications including neurovascular and stroke research. This chapter will prepare the reader for rodent experiments using LDF with two preparations. The closed skull preparation can be used to monitor CBF with an intact skull, but in adult rats, thinning of the skull is required to obtain an accurate cortical CBF signal. The open skull preparation requires a craniotomy to expose the surface of the brain and the LDF probe is held close to the surface to measure cerebral perfusion.

  13. Heat flux measurement in a high enthalpy plasma flow

    NASA Astrophysics Data System (ADS)

    Löhle, Stefan; Battaglia, Jean-Luc; Gardarein, Jean-Laurent; Jullien, Pierre; van Ootegem, Bruno

    2008-11-01

    It is a widely used approach to measure heat flux in harsh environments like high enthalpy plasma flows, fusion plasma and rocket motor combustion chambers based on solving the inverse heat conduction problem in a semi-infinite environment. This approach strongly depends on model parameters and geometrical aspects of the sensor design. In this work the surface heat flux is determined by solving the inverse heat conduction problem using an identified system as a direct model. The identification of the system is performed using calibration measurements with modern laser technique and advanced data handling. The results of the identified thermo-physical system show that a non-integer model appears most adapted to this particular problem. It is concluded that the new method improves the heat flux sensor significantly and furthermore extend its application to very short measurement times.

  14. Langmuir-probe measurements in flowing-afterglow plasmas

    SciTech Connect

    Johnsen, R.; Shun'ko, E.V.; Gougousi, T. ); Golde, M.F. )

    1994-11-01

    The validity of the orbital-motion theory for cylindrical Langmuir probes immersed in flowing-afterglow plasmas is investigated experimentally. It is found that the probe currents scale linearly with probe area only for electron-collecting but not for ion-collecting probes. In general, no agreement is found between the ion and electron densities derived from the probe currents. Measurements in recombining plasmas support the conclusion that only the [ital electron] densities derived from probe measurements can be trusted to be of acceptable accuracy. This paper also includes a brief derivation of the orbital-motion theory, a discussion of perturbations of the plasma by the probe current, and the interpretation of plasma velocities obtained from probe measurements.

  15. Langmuir-Probe Measurements in Flowing-Afterglow Plasmas

    NASA Technical Reports Server (NTRS)

    Johnsen, R.; Shunko, E. V.; Gougousi, T.; Golde, M. F.

    1994-01-01

    The validity of the orbital-motion theory for cylindrical Langmuir probes immersed in flowing- afterglow plasmas is investigated experimentally. It is found that the probe currents scale linearly with probe area only for electron-collecting but not for ion-collecting probes. In general, no agreement is found between the ion and electron densities derived from the probe currents. Measurements in recombining plasmas support the conclusion that only the electron densities derived from probe measurements can be trusted to be of acceptable accuracy. This paper also includes a brief derivation of the orbital-motion theory, a discussion of perturbations of the plasma by the probe current, and the interpretation of plasma velocities obtained from probe measurements.

  16. Langmuir-probe measurements in flowing-afterglow plasmas

    NASA Astrophysics Data System (ADS)

    Johnsen, R.; Shun'ko, E. V.; Gougousi, T.; Golde, M. F.

    1994-11-01

    The validity of the orbital-motion theory for cylindrical Langmuir probes immersed in flowing-afterglow plasmas is investigated experimentally. It is found that the probe currents scale linearly with probe area only for electron-collecting but not for ion-collecting probes. In general, no agreement is found between the ion and electron densities derived from the probe currents. Measurements in recombining plasmas support the conclusion that only the electron densities derived from probe measurements can be trusted to be of acceptable accuracy. This paper also includes a brief derivation of the orbital-motion theory, a discussion of perturbations of the plasma by the probe current, and the interpretation of plasma velocities obtained from probe measurements.

  17. Flow cytomeric measurement of DNA and incorporated nucleoside analogs

    DOEpatents

    Dolbeare, Frank A.; Gray, Joe W.

    1989-01-01

    A method is provided for simultaneously measuring total cellular DNA and incorporated nucleoside analog. The method entails altering the cellular DNA of cells grown in the presence of a nucleoside analog so that single stranded and double stranded portions are present. Separate stains are used against the two portions. An immunochemical stain is used against the single stranded portion to provide a measure of incorporated nucleoside analog, and a double strand DNA-specific stain is used against the double stranded portion to simultaneously provide a measure of total cellular DNA. The method permits rapid flow cytometric analysis of cell populations, rapid identification of cycling and noncycling subpopulations, and determination of the efficacy of S phase cytotoxic anticancer agents.

  18. Skin friction measurements in high temperature high speed flows

    NASA Technical Reports Server (NTRS)

    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. Numerical modeling of separated flows at moderate Reynolds numbers appropriate for turbine blades and unmanned aero vehicles

    NASA Astrophysics Data System (ADS)

    Castiglioni, Giacomo

    Flows over airfoils and blades in rotating machinery, for unmanned and micro-aerial vehicles, wind turbines, and propellers consist of a laminar boundary layer near the leading edge that is often followed by a laminar separation bubble and transition to turbulence further downstream. Typical Reynolds averaged Navier-Stokes turbulence models are inadequate for such flows. Direct numerical simulation is the most reliable, but is also the most computationally expensive alternative. This work assesses the capability of immersed boundary methods and large eddy simulations to reduce the computational requirements for such flows and still provide high quality results. Two-dimensional and three-dimensional simulations of a laminar separation bubble on a NACA-0012 airfoil at Rec = 5x104 and at 5° of incidence have been performed with an immersed boundary code and a commercial code using body fitted grids. Several sub-grid scale models have been implemented in both codes and their performance evaluated. For the two-dimensional simulations with the immersed boundary method the results show good agreement with the direct numerical simulation benchmark data for the pressure coefficient Cp and the friction coefficient Cf, but only when using dissipative numerical schemes. There is evidence that this behavior can be attributed to the ability of dissipative schemes to damp numerical noise coming from the immersed boundary. For the three-dimensional simulations the results show a good prediction of the separation point, but an inaccurate prediction of the reattachment point unless full direct numerical simulation resolution is used. The commercial code shows good agreement with the direct numerical simulation benchmark data in both two and three-dimensional simulations, but the presence of significant, unquantified numerical dissipation prevents a conclusive assessment of the actual prediction capabilities of very coarse large eddy simulations with low order schemes in general

  20. Biochemical oxygen demand measurement by mediator method in flow system.

    PubMed

    Liu, Ling; Bai, Lu; Yu, Dengbin; Zhai, Junfeng; Dong, Shaojun

    2015-06-01

    Using mediator as electron acceptor for biochemical oxygen demand (BOD) measurement was developed in the last decade (BODMed). However, until now, no BOD(Med) in a flow system has been reported. This work for the first time describes a flow system of BOD(Med) method (BOD(Med)-FS) by using potassium ferricyanide as mediator and carbon fiber felt as substrate material for microbial immobilization. The system can determine the BOD value within 30 min and possesses a wider analytical linear range for measuring glucose-glutamic acid (GGA) standard solution from 2 up to 200 mg L(-1) without the need of dilution. The analytical performance of the BOD(Med)-FS is comparable or better than that of the previously reported BOD(Med) method, especially its superior long-term stability up to 2 months under continuous operation. Moreover, the BOD(Med)-FS has same determination accuracy with the conventional BOD5 method by measuring real samples from a local wastewater treatment plant (WWTP).

  1. Response of Sap-Flow Measurements on Environmental Forcings

    NASA Astrophysics Data System (ADS)

    Howe, J. A.; Dragoni, D.; Schmid, H.

    2005-05-01

    The exchange of water between the atmosphere and biosphere is an important determinant of climate and the productivity of vegetation. Both evaporation and transpiration involve substantial amounts of energy exchange at the interface of the biosphere and atmosphere. Knowing how transpiration changes throughout the seasonal and diurnal cycles can help increase the understanding of how a forest reacts to changes in the biosphere and atmosphere. A common way to estimate transpiration is by measuring the sap flowing through the living tissues of trees. A study was conducted at Morgan-Monroe State Forest, a mixed deciduous forest in south central Indiana (USA), to investigate how sap flow in trees responds to changes in meteorological and environmental conditions. The heat -dissipation technique was used to estimate sap velocities from two Big Tooth Aspen (Populus grandidentata) and two Tulip Poplars (Liriodendron tulipifera). Sap velocity patterns (normalized by a reference potential evapo-transpiration) were directly compared with meteorological and ecological measurements, such as vapor pressure deficits, photosynthetic active radiation (PAR), rain fall, and soil moisture content. In this study, we also investigated the uncertainties and problems that arise in using the heat dissipation technique to extrapolate the single-tree measurements to the forest scale.

  2. Visualization of turbulent flows with simultaneous velocity and vorticity measurements

    NASA Astrophysics Data System (ADS)

    Ong, Lawrence

    1992-09-01

    An experimental study of the turbulent boundary layer at Re(sub theta) approx. equals 1070 was conducted. This study combines velocity and vorticity measurements using a nine-sensor hot-wire probe with simultaneously obtained flow visualization images. Detailed measurements within the boundary layer with and without smoke marking of the wall layer fluid were performed at various distances from the wall, ranging from approximately y(+) approx. equals 14 to y(+) approx. equals 156, and at three axial locations downstream from the smoke injection slot. The mean statistical properties of the fluctuating velocity and vorticity components agree well with previous experimental and numerically simulated data. These boundary layer measurements were used in a joint probability analysis of the various instantaneous velocity, velocity gradient and vorticity correlations that appear in the vorticity and enstrophy transport equations. Substantial evidence supporting postulated inclined vortex models was found. Conditional analysis based on the detection of strong Reynolds stress and enstrophy events was carried out. The combined visual and hot-wire data provide evidence showing that these smoke marked regions in the flow field, which indicate vertical mass flux, are also regions of high vertical momentum flux.

  3. Methods for blood flow measurements using ultrasound contrast agents

    NASA Astrophysics Data System (ADS)

    Fowlkes, J. Brian

    2003-10-01

    Blood flow measurements using ultrasound contrast agents are being investigated for myocardial perfusion and more recently in other organ systems. The methods are based largely on the relative increase in echogenicity due to the concentration of bubbles present in the ultrasound beam. In the simplest form, regional differences in blood volume can be inferred but the possibility exists to extract perfusion from the transit of contrast agent through tissue. Perfusion measurements rely on determining the flux of blood through a tissue volume and as such require knowledge of the fractional blood volume (FBV), i.e., ml blood/g tissue and the rate of exchange, commonly measured as the mean transit time (MTT). This presentation will discuss methods of determining each of these values and their combination to estimate tissue perfusion. Underlying principles of indicator-dilution theory will be provided in the context of ultrasound contrast agents. Current methods for determining MTT will include imaging of the intravenous bolus, in-plane contrast disruption with interval and real-time contrast recovery imaging, and control of contrast agent flow using arterial disruption (contrast interruption). The advantages and limitations of the methods will be examined along with current applications. [Work supported in part by NIH.

  4. Pulsed Electron Beam Spectroscopy for Temperature Measurements in Hypersonic Flows

    DTIC Science & Technology

    2010-01-01

    atmospheric pr essures wit hin the fligh t envelope of scramjet-powered flight vehicles. Because of the pressure disparity between measured flow and me...represents what might be o btained from the pulse d e-beam s ystem if it were used in the high-te mperature (but high-pr essure ) st agnation cha...di fferential pressure pump has been developed for pressure separations up to approximately 1 torr. F or higher pr essures , a f ast act ion r otary

  5. Measuring Cell Viscoelastic Properties Using a Microfluidic Extensional Flow Device.

    PubMed

    Guillou, Lionel; Dahl, Joanna B; Lin, Jung-Ming G; Barakat, AbduI I; Husson, Julien; Muller, Susan J; Kumar, Sanjay

    2016-11-01

    The quantification of cellular mechanical properties is of tremendous interest in biology and medicine. Recent microfluidic technologies that infer cellular mechanical properties based on analysis of cellular deformations during microchannel traversal have dramatically improved throughput over traditional single-cell rheological tools, yet the extraction of material parameters from these measurements remains quite complex due to challenges such as confinement by channel walls and the domination of complex inertial forces. Here, we describe a simple microfluidic platform that uses hydrodynamic forces at low Reynolds number and low confinement to elongate single cells near the stagnation point of a planar extensional flow. In tandem, we present, to our knowledge, a novel analytical framework that enables determination of cellular viscoelastic properties (stiffness and fluidity) from these measurements. We validated our system and analysis by measuring the stiffness of cross-linked dextran microparticles, which yielded reasonable agreement with previously reported values and our micropipette aspiration measurements. We then measured viscoelastic properties of 3T3 fibroblasts and glioblastoma tumor initiating cells. Our system captures the expected changes in elastic modulus induced in 3T3 fibroblasts and tumor initiating cells in response to agents that soften (cytochalasin D) or stiffen (paraformaldehyde) the cytoskeleton. The simplicity of the device coupled with our analytical model allows straightforward measurement of the viscoelastic properties of cells and soft, spherical objects.

  6. Further time-mean measurements in confined swirling flows

    NASA Astrophysics Data System (ADS)

    Lilley, D. G.; Yoon, H. K.

    1984-04-01

    Nonswirling and swirling nonreacting flows in an axisymmetric test section with an expansion ratio D/d = 2, which may be equipped with contraction nozzles of area ratios 2 and 4, are investigated. The effects of a number of geometric parameters on the flow-field are investigated, among them side-wall expansion angles of 90 and 45 deg, swirl vane angles of 0, 38, 45, 60, and 70 deg, and contraction nozzle locations L/D = 1 and 2 (if present). Data are acquired by means of a five-hole pitot probe enabling three time-mean velocity components in the axial, radial, and azimuthal directions to be measured. The velocities are extensively plotted and artistic impressions of recirculation zones are set forth. The presence of a swirler is found to shorten the corner recirculation zone and to generate a central recirculation zone followed by a precessing vortex core. A gradual inlet expansion has the effect of encouraging the flow to remain close to the sidewall and shortening the extent of the corner recirculation zone in all cases investigated.

  7. Device for accurately measuring mass flow of gases

    DOEpatents

    Hylton, J.O.; Remenyik, C.J.

    1994-08-09

    A device for measuring mass flow of gases which utilizes a substantially buoyant pressure vessel suspended within a fluid/liquid in an enclosure is disclosed. The pressure vessel is connected to a weighing device for continuously determining weight change of the vessel as a function of the amount of gas within the pressure vessel. In the preferred embodiment, this pressure vessel is formed from inner and outer right circular cylindrical hulls, with a volume between the hulls being vented to the atmosphere external the enclosure. The fluid/liquid, normally in the form of water typically with an added detergent, is contained within an enclosure with the fluid/liquid being at a level such that the pressure vessel is suspended beneath this level but above a bottom of the enclosure. The buoyant pressure vessel can be interconnected with selected valves to an auxiliary pressure vessel so that initial flow can be established to or from the auxiliary pressure vessel prior to flow to or from the buoyant pressure vessel. 5 figs.

  8. Device for accurately measuring mass flow of gases

    DOEpatents

    Hylton, James O.; Remenyik, Carl J.

    1994-01-01

    A device for measuring mass flow of gases which utilizes a substantially buoyant pressure vessel suspended within a fluid/liquid in an enclosure. The pressure vessel is connected to a weighing device for continuously determining weight change of the vessel as a function of the amount of gas within the pressure vessel. In the preferred embodiment, this pressure vessel is formed from inner and outer right circular cylindrical hulls, with a volume between the hulls being vented to the atmosphere external the enclosure. The fluid/liquid, normally in the form of water typically with an added detergent, is contained within an enclosure with the fluid/liquid being at a level such that the pressure vessel is suspended beneath this level but above a bottom of the enclosure. The buoyant pressure vessel can be interconnected with selected valves to an auxiliary pressure vessel so that initial flow can be established to or from the auxiliary pressure vessel prior to flow to or from the buoyant pressure vessel.

  9. Evaluation of a Multicommuted Flow System for Photometric Environmental Measurements

    PubMed Central

    Ródenas-Torralba, Eva; Rocha, Fábio R. P.; Reis, Boaventura F.; de la Guardia, Miguel

    2006-01-01

    A portable flow analysis instrument is described for in situ photometric measurements. This system is based on light-emitting diodes (LEDs) and a photodiode detector, coupled to a multipumping flow system. The whole equipment presents dimensions of 25  cm × 22  cm × 10  cm, weighs circa 3 kg, and costs 650 €. System performance was evaluated for different chemistries without changing hardware configuration for determinations of (i) Fe3+ with SCN-, (ii) iodometric nitrite determination, (iii) phenol with sodium nitroprusside, and (iv) 1-naphthol-N-methylcarbamate (carbaryl) with p-aminophenol. The detection limits were estimated as 22, 60, 25, and 60 ng mL -1 for iron, nitrite, phenol, and carbaryl at the 99.7% confidence level with RSD of 2.3, 1.0, 1.8, and 0.8%, respectively. Reagent and waste volumes were lower than those obtained by flow systems with continuous reagent addition. Sampling rates of 100, 110, 65, and 72 determinations per hour were achieved for iron, nitrite, phenol, and carbaryl determinations PMID:17671614

  10. Device and method for measuring multi-phase fluid flow in a conduit using an elbow flow meter

    DOEpatents

    Ortiz, M.G.; Boucher, T.J.

    1997-06-24

    A system is described for measuring fluid flow in a conduit. The system utilizes pressure transducers disposed generally in line upstream and downstream of the flow of fluid in a bend in the conduit. Data from the pressure transducers is transmitted to a microprocessor or computer. The pressure differential measured by the pressure transducers is then used to calculate the fluid flow rate in the conduit. Control signals may then be generated by the microprocessor or computer to control flow, total fluid dispersed, (in, for example, an irrigation system), area of dispersal or other desired effect based on the fluid flow in the conduit. 2 figs.

  11. Device and method for measuring multi-phase fluid flow in a conduit using an elbow flow meter

    DOEpatents

    Ortiz, Marcos G.; Boucher, Timothy J.

    1997-01-01

    A system for measuring fluid flow in a conduit. The system utilizes pressure transducers disposed generally in line upstream and downstream of the flow of fluid in a bend in the conduit. Data from the pressure transducers is transmitted to a microprocessor or computer. The pressure differential measured by the pressure transducers is then used to calculate the fluid flow rate in the conduit. Control signals may then be generated by the microprocessor or computer to control flow, total fluid dispersed, (in, for example, an irrigation system), area of dispersal or other desired effect based on the fluid flow in the conduit.

  12. A novel technique to measure subsurface flow velocity

    NASA Astrophysics Data System (ADS)

    Bachmair, S.; Weiler, M.

    2010-12-01

    To better understand subsurface flow (SSF) processes at the hillslope scale, measuring subsurface flow velocity should be of great interest. However, due to the large heterogeneity in time and space, we are faced with the need to continuously measure SSF velocity at several locations within a hillslope over a distance being representative for certain hillslope segments. At present, SSF velocity is either measured by tracer tests over larger distances or via centimeter-scale measurements using heat dissipation or other tracers. This calls for a cheap and easily applicable method to continuously detect subsurface flow velocity in the field over a distance representative for certain hillslope segments. We currently develop a novel technique, which has shown promising results in the laboratory. The technique is based on an automatic salt tracer injection into a small-diameter borehole once the soil matrix has reached saturation. The tracer signal is captured by a 5TE probe (Decagon Devices) measuring soil moisture, electrical conductivity, and temperature every two minutes, which is inserted a few decimetres downslope of the injection point into the soil. The automatic injection is also controlled by the 5TE probe, which is connected to a CR1000 Logger (Campbell Scientific). Once saturated conditions have been established, a plug valve attached to an above-mounted bottle with NaCl solution is opened for 2 seconds and the tracer is injected into the borehole via a small steel tube screened at the bottom. Under saturated conditions the automatic injection is conducted every two hours and the breakthrough curves are analyzed for the mean effective velocity. In a first step, the technique was tested in a sand filled box with constant in- and outflow conditions representing a homogeneous miniature hillslope. Several experimental set-ups differing in hydraulic gradient, distance from injection point to 5TE probe, orientation of 5TE probe, and amount and concentration of

  13. Measurement and modelling of sap flow in maize plants

    NASA Astrophysics Data System (ADS)

    Heinlein, Florian; Biernath, Christian; Hoffmann, Peter; Klein, Christian; Thieme, Christoph; Priesack, Eckart

    2014-05-01

    Climate change as well as the changing composition of the atmosphere will have an impact on future yield of agricultural plants. In order to better estimate these impacts new, mechanistic plant growth models are needed. These models should be able to dynamically reproduce the plants' reactions to modified climate state variables like temperature, atmospheric CO2-concentration and water availability. In particular, to better describe the crop response to more strongly changing water availability the simulation of plant-internal water and solute transport processes in xylem and phloem needs to be improved. Our existing water transport model consists of two coupled 1-D Richards equations to calculate water transport in the soil and in the plants. This model has already been successfully applied to single Fagus sylvatica L. trees. At present it is adapted to agricultural plants such as maize. To simulate the water transport within the plants a representation of the flow paths, i.e. the plant architecture, is required. Aboveground plant structures are obtained from terrestrial laser scan (TLS) measurements at different development stages. These TLSs have been executed at the lysimeter facilities of Helmholtz Zentrum München and at the TERENO (Terrestrial Environmental Observatories) research farm Scheyern. Additionally, an L-system model is used to simulate aboveground and belowground plant architectures. In a further step, the quality of the explicit water flow model has to be tested using measurements. The Heat-Ratio-Method has been employed to directly measure sap flow in larger maize plants during a two-months-period in summer 2013 with a resolution of 10 minutes and thus, the plants' transpiration can be assessed. Water losses from the soil are determined by measuring the weight of lysimeters. From this evapotranspiration can be calculated. Transpiration and evapotranspiration are also simulated by application of the modelling system Expert-N. This framework

  14. Flow measurements in the edge plasma of Tore Supra

    NASA Astrophysics Data System (ADS)

    Boucher, C.; Thibault, L.-G.; Gunn, J. P.; Pascal, J.-Y.; Devynck, P.; Tore Supra Team

    2001-03-01

    In recent years, the measurement of flow velocity of the plasma in the edge of tokamaks has gained in importance. The determination of this parameter is often done using electrostatic probe systems such as Mach probes or Gundestrup probes. A Gundestrup system was recently commissioned in Tore Supra. The perpendicular ( U⊥) and parallel ( U//) components of the velocity are determined from the six ion saturation currents using a neural network. The neural network was trained using ion saturation currents obtained from a two-dimensional kinetic code developed at Tore Supra. We will describe the Gundestrup probe and the neural network training, validation and implementation. Preliminary measurements in ergodic divertor discharges show U// and U⊥ profiles that exhibit small-scale spatial modulations similar to those reported for the temperature profiles.

  15. Measurement of two-phase flow momentum with force transducers

    SciTech Connect

    Hardy, J.E.; Smith, J.E.

    1990-01-01

    Two strain-gage-based drag transducers were developed to measure two-phase flow in simulated pressurized water reactor (PWR) test facilities. One transducer, a drag body (DB), was designed to measure the bidirectional average momentum flux passing through an end box. The second drag sensor, a break through detector (BTD), was designed to sense liquid downflow from the upper plenum to the core region. After prototype sensors passed numerous acceptance tests, transducers were fabricated and installed in two experimental test facilities, one in Japan and one in West Germany. High-quality data were extracted from both the DBs and BTDs for a variety of loss-of-coolant accident (LOCA) scenarios. The information collected from these sensors has added to the understanding of the thermohydraulic phenomena that occur during the refill/reflood stage of a LOCA in a PWR. 9 refs., 15 figs.

  16. Phased-Array Measurements of Single Flow Hot Jets

    NASA Technical Reports Server (NTRS)

    Bridges, James; Lee, Sang Soo

    2005-01-01

    A 16 microphone phased-array system has been successfully applied to measure jet noise source distributions. In this study, a round convergent nozzle was tested at various hot and cold flow conditions: acoustic Mach numbers are between 0.35 and 1.6 and static temperature ratios are varied from cold to 2.7. The classical beamforming method was applied on narrowband frequencies. From the measured source distributions locations of peak strength were tracked and found to be very consistent between adjacent narrowband frequencies. In low speed heated and unheated jets, the peak source locations vary smoothly from the nozzle exit to downstream as the frequency is decreased. When the static temperature ratio was kept constant, the peak source position moved downstream with increasing acoustic Mach number for the Strouhal numbers smaller than about 1.5. It was also noted that the peak source locations of low frequencies occur farther downstream than the end of potential core.

  17. Groundwater flow speed measurement using an electrolyte antenna

    NASA Astrophysics Data System (ADS)

    Crews, J. B.; Schumer, R.

    2015-12-01

    Most hydrogeophysical methods focus on subsurface structure, water content, and other properties that can be used to infer flow properties, but only the combination of self-potential and resistivity has thus far been used to estimate water flux. Exploiting the inverse relationship between the length of a wire antenna and its electrical resonant frequency, an aqueous electrolyte solution can be injected into a borehole, and the rate at which the leading edge of the plume advances can be determined by measuring the time-rate-of-change of the plume's electrical resonant frequency using a commercial antenna analyzer. Experiments were conducted to calibrate the relationship between the electrical resonant frequency of the electrolyte plume and its physical length in water-saturated porous media. Length-versus-resonant-frequency calibration obtained from measurements on wires housed in buried conduits representing preferential flow paths through a model aquifer exhibit close agreement with theoretical predictions based on theory describing the behavior of wire antennas in air. The advantages of this method for subsurface characterization include that it is 1) deployable by one person, 2) not dependent on inversion methods, 3) effective in a single borehole, and 4) not scale dependent.

  18. Measurements of Reynolds stress profiles in unstratified tidal flow

    USGS Publications Warehouse

    Stacey, M.T.; Monismith, Stephen G.; Burau, J.R.

    1999-01-01

    In this paper we present a method for measuring profiles of turbulence quantities using a broadband acoustic doppler current profiler (ADCP). The method follows previous work on the continental shelf and extends the analysis to develop estimates of the errors associated with the estimation methods. ADCP data was collected in an unstratified channel and the results of the analysis are compared to theory. This comparison shows that the method provides an estimate of the Reynolds stresses, which is unbiased by Doppler noise, and an estimate of the turbulent kinetic energy (TKE) which is biased by an amount proportional to the Doppler noise. The noise in each of these quantities as well as the bias in the TKE match well with the theoretical values produced by the error analysis. The quantification of profiles of Reynolds stresses simultaneous with the measurement of mean velocity profiles allows for extensive analysis of the turbulence of the flow. In this paper, we examine the relation between the turbulence and the mean flow through the calculation of u*, the friction velocity, and Cd, the coefficient of drag. Finally, we calculate quantities of particular interest in turbulence modeling and analysis, the characteristic lengthscales, including a lengthscale which represents the stream-wise scale of the eddies which dominate the Reynolds stresses. Copyright 1999 by the American Geophysical Union.

  19. Measurement and Characterization of Apoptosis by Flow Cytometry.

    PubMed

    Telford, William; Tamul, Karen; Bradford, Jolene

    2016-07-01

    Apoptosis is an important mechanism in cell biology, playing a critical regulatory role in virtually every organ system. It has been particularly well characterized in the immune system, with roles ranging from immature immune cell development and selection to down-regulation of the mature immune response. Apoptosis is also the primary mechanism of action of anti-cancer drugs. Flow cytometry has been the method of choice for analyzing apoptosis in suspension cells for more than 25 years. Numerous assays have been devised to measure both the earliest and latest steps in the apoptotic process, from the earliest signal-transduction events to the late morphological changes in cell shape and granularity, proteolysis, and chromatin condensation. These assays are particularly powerful when combined into multicolor assays determining several apoptotic characteristics simultaneously. The multiparametric nature of flow cytometry makes this technology particularly suited to measuring apoptosis. In this unit, we will describe the four main techniques for analyzing caspase activity in apoptotic cells, combined with annexin V and cell permeability analysis. These relatively simple multiparametric assays are powerful techniques for assessing cell death. © 2016 by John Wiley & Sons, Inc.

  20. Thermal and flow measurements of continuous cryogenic spray cooling.

    PubMed

    Hsieh, Shou-Shing; Tsai, Huang-Hsiu

    2006-07-01

    The performance of single sprays for high heat flux cooling using R-134a was studied. The heat flux and heat transfer coefficient at the surface of a sprayed jet based on measurements of steady-state temperature gradients on a thin copper plate during continuous spraying. Meanwhile, the spray droplets flow characteristics was also quantified through laser doppler velocimetry (LDV) measurements to obtain the local velocity distributions. The effects of mass flow rate and average droplet velocity, and spray exit-to-target distance on the surface heat flux including the corresponding critical heat flux (CHF) were explored through three different nozzle diameters of 0.2, 0.3, and 0.4 mm. Finally, the effective use of the fluid being delivered based on the cooling efficiency and cooling effectiveness was also examined. The relationship between CHF and nozzle performance in terms of cooling efficiency and cooling effectiveness was found. The heat transfer removal rate can reach up to 140 W/cm(2) for the present nozzle size of d (j)=0.2 and 0.3 mm, which may enhance the current cryogen spray cooling (CSC) technique that assists laser therapy of dermatoses.

  1. Flow mediated endothelium function: advantages of an automatic measuring technique

    NASA Astrophysics Data System (ADS)

    Maio, Yamila; Casciaro, Mariano E.; José Urcola y, Maria; Craiem, Damian

    2007-11-01

    The objective of this work is to show the advantages of a non invasive automated method for measuring flow mediated dilation (FMD) in the forearm. This dilation takes place in answer to a shear tension generated by the increase of blood flow, sensed by the endothelium, after the liberation of an occlusion sustained in the time. The method consists of three stages: the continuous acquisition of images of the brachial artery using ultrasound techniques, the pulse to pulse measurement of the vessel's diameter by means of a border detection algorithm, and the later analysis of the results. By means of this technique one cannot only obtain the maximum dilation percentage (FMD%), but a continuous diameter curve that allows to evaluate other relevant aspects such as dilation speed, dilation sustain in time and general maneuver performance. The simplicity of this method, robustness of the technique and accessibility of the required elements makes it a viable alternative of great clinical value for diagnosis in the early detection of numerous cardiovascular pathologies.

  2. Characterizing blood cells by biophysical measurements in flow.

    PubMed

    Groner, W; Tycko, D

    1980-01-01

    One effect of automation in the hematology laboratory has been to introduce new characterizations of blood cells. Resistive pulse sensing (Coulter) and light scatter measurements in flow provide rapid and reproducible cell counts. They also provide information about red cell size, shape, and deformability. Thus, they have provided new characterization of these cells in terms of their biophysical properties. Leukocytes have been classified by optical scatter and absorption measurements in flow after being stained cytochemically. This provides rapid and precise WBC differential counts. However, here again, additional information about relative cell-enzyme content or activity is also accessible to provide a new characterization of the leukocytes. The ultimate range of utility of this expanding technology in the automated hematology laboratory of the future will, of course, depend upon establishing relations between the biophysical parameters and the functions of the cells. This, in turn, must depend upon the use of the technology by researchers and clinicians in studying cell function and the aberrations of these functions which define disease.

  3. 40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement... practice. (2) Flow air through the calibration system at the sample flow rate used for particulate testing... standard device. (4) Calculate air flow at standard conditions as measured by both the standard device...

  4. 40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement... practice. (2) Flow air through the calibration system at the sample flow rate used for particulate testing... standard device. (4) Calculate air flow at standard conditions as measured by both the standard device...

  5. 40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement... practice. (2) Flow air through the calibration system at the sample flow rate used for particulate testing... standard device. (4) Calculate air flow at standard conditions as measured by both the standard device...

  6. 40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement... practice. (2) Flow air through the calibration system at the sample flow rate used for particulate testing... standard device. (4) Calculate air flow at standard conditions as measured by both the standard device...

  7. 40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement... practice. (2) Flow air through the calibration system at the sample flow rate used for particulate testing... standard device. (4) Calculate air flow at standard conditions as measured by both the standard device...

  8. Measurements of the flow and turbulence characteristics of round jets in cross flow

    NASA Astrophysics Data System (ADS)

    Sherif, S. A.; Pletcher, R. H.

    1986-05-01

    Measurements of the velocity and turbulence characteristics of a round turbulent jet in cross flow are reported. The experiments were conducted in a water channel, 8.53 m long, 0.61 m wide, and 1.067 m deep, of the recirculation type. Water was injected vertically upward from a circular pipe located near the channel bottom to simulate the turbulent jet. Normal and 45 deg-slanted fiber-film probes along with appropriate anemometers and bridges were operated in the constant temperature mode to measure mean velocities, turbulence intensities, Reynolds stresses, structural parameters, correlation coefficients, and the turbulent kinetic energy. The measurements were carried out in the jet and its wake both in and outside the jet plane of symmetry.

  9. Debris flow cartography using differential GNSS and Theodolite measurements

    NASA Astrophysics Data System (ADS)

    Khazaradze, Giorgi; Guinau, Marta; Calvet, Jaume; Furdada, Gloria; Victoriano, Ane; Génova, Mar; Suriñach, Emma

    2016-04-01

    The presented results form part of a CHARMA project, which pursues a broad objective of reducing damage caused by uncontrolled mass movements, such as rockfalls, snow avalanches and debris flows. Ultimate goal of the project is to contribute towards the establishment of new scientific knowledge and tools that can help in the design and creation of early warning systems. Here we present the specific results that deal with the application of differential GNSS and classical geodetic (e.g. theodolite) methods for mapping debris and torrential flows. Specifically, we investigate the Portainé stream located in the Pallars Sobirà region of Catalonia (Spain), in the eastern Pyrenees. In the last decade more than ten debris-flow type phenomena have affected the region, causing considerable economic losses. Since early 2014, we have conducted several field campaigns within the study area, where we have employed a multi-disciplinary approach, consisting of geomorphological, dendro-chronological and geodetic methods, in order to map the river bed and reconstruct the history of the extreme flooding and debris flow events. Geodetic studies included several approaches, using the classical and satellite based methods. The former consisted of angle and distance measurements between the Geodolite 502 total station and the reflecting prisms placed on top of the control points located within the riverbed. These type of measurements are precise, although present several disadvantages such as the lack of absolute coordinates that makes the geo-referencing difficult, as well as a relatively time-consuming process that involves two persons. For this reason, we have also measured the same control points using the differential GNSS system, in order to evaluate the feasibility of replacing the total station measurements with the GNSS. The latter measuring method is fast and can be conducted by one person. However, the fact that the study area is within the riverbed, often below the trees

  10. A comparison of predicted and measured inlet distortion flows in a subsonic axial inlet flow compressor rotor

    NASA Technical Reports Server (NTRS)

    Owen, Albert K.

    1992-01-01

    Detailed flow measurements were taken inside an isolated axial compressor rotor operating subsonically near peak efficiency. These Laser Anemometer measurements were made with two inlet velocity profiles. One profile consisted of an unmodified baseline flow, and the second profile was distorted by placing axisymmetric screens on the hub and shroud well upstream of the rotor. A detailed comparison in the rotor relative reference frame between a Navier-Stokes solver and the measured experimental results showed good agreement between the predicted and measured flows. A primary flow is defined in the rotor and deviations and the computed predictions is made to assess the development of a passage vortex due to the distortion of the inlet flow. Computer predictions indicate that a distorted inlet profile has a minimal effect on the development of the flow in the rotor passage and the resulting passage vortex.

  11. Measurement and Computation of Supersonic Flow in a Lobed Diffuser-Mixer for Trapped Vortex Combustors

    NASA Technical Reports Server (NTRS)

    Brankovic, Andreja; Ryder, Robert C., Jr.; Hendricks, Robert C.; Liu, Nan-Suey; Gallagher, John R.; Shouse, Dale T.; Roquemore, W. Melvyn; Cooper, Clayton S.; Burrus, David L.; Hendricks, John A.

    2002-01-01

    The trapped vortex combustor (TVC) pioneered by Air Force Research Laboratories (AFRL) is under consideration as an alternative to conventional gas turbine combustors. The TVC has demonstrated excellent operational characteristics such as high combustion efficiency, low NO(x) emissions, effective flame stabilization, excellent high-altitude relight capability, and operation in the lean-burn or rich burn-quick quench-lean burn (RQL) modes of combustion. It also has excellent potential for lowering the engine combustor weight. This performance at low to moderate combustor mach numbers has stimulated interest in its ability to operate at higher combustion mach number, and for aerospace, this implies potentially higher flight mach numbers. To this end, a lobed diffuser-mixer that enhances the fuel-air mixing in the TVC combustor core was designed and evaluated, with special attention paid to the potential shock system entering the combustor core. For the present investigation, the lobed diffuser-mixer combustor rig is in a full annular configuration featuring sixfold symmetry among the lobes, symmetry within each lobe, and plain parallel, symmetric incident flow. During hardware cold-flow testing, significant discrepancies were found between computed and measured values for the pitot-probe-averaged static pressure profiles at the lobe exit plane. Computational fluid dynamics (CFD) simulations were initiated to determine whether the static pressure probe was causing high local flow-field disturbances in the supersonic flow exiting the diffuser-mixer and whether shock wave impingement on the pitot probe tip, pressure ports, or surface was the cause of the discrepancies. Simulations were performed with and without the pitot probe present in the modeling. A comparison of static pressure profiles without the probe showed that static pressure was off by nearly a factor of 2 over much of the radial profile, even when taking into account potential axial displacement of the

  12. A New Method for Flow Rate Measurement in Millimeter-Scale Pipes

    PubMed Central

    Ji, Haifeng; Gao, Xuemin; Wang, Baoliang; Huang, Zhiyao; Li, Haiqing

    2013-01-01

    Combining the Capacitively Coupled Contactless Conductivity Detection (C4D) technique and the principle of cross correlation flow measurement, a new method for flow rate measurement in millimeter-scale pipes was proposed. The research work included two parts. First, a new five-electrode C4D sensor was developed. Second, with two conductivity signals obtained by the developed sensor, the flow rate measurement was implemented by using the principle of cross correlation flow measurement. The experimental results showed that the proposed flow rate measurement method was effective, the developed five-electrode C4D sensor was successful, and the measurement accuracy was satisfactory. In five millimeter-scale pipes with different inner diameters of 0.5, 0.8, 1.8, 3.0 and 3.9 mm respectively, the maximum relative difference of the flow rate measurement between the reference flow rate and the measured flow rate was less than 5%. PMID:23353139

  13. Simultaneous Moisture Content and Mass Flow Measurements in Wood Chip Flows Using Coupled Dielectric and Impact Sensors

    PubMed Central

    Pan, Pengmin; McDonald, Timothy; Fulton, John; Via, Brian; Hung, John

    2016-01-01

    An 8-electrode capacitance tomography (ECT) sensor was built and used to measure moisture content (MC) and mass flow of pine chip flows. The device was capable of directly measuring total water quantity in a sample but was sensitive to both dry matter and moisture, and therefore required a second measurement of mass flow to calculate MC. Two means of calculating the mass flow were used: the first being an impact sensor to measure total mass flow, and the second a volumetric approach based on measuring total area occupied by wood in images generated using the capacitance sensor’s tomographic mode. Tests were made on 109 groups of wood chips ranging in moisture content from 14% to 120% (dry basis) and wet weight of 280 to 1100 g. Sixty groups were randomly selected as a calibration set, and the remaining were used for validation of the sensor’s performance. For the combined capacitance/force transducer system, root mean square errors of prediction (RMSEP) for wet mass flow and moisture content were 13.42% and 16.61%, respectively. RMSEP using the combined volumetric mass flow/capacitance sensor for dry mass flow and moisture content were 22.89% and 24.16%, respectively. Either of the approaches was concluded to be feasible for prediction of moisture content in pine chip flows, but combining the impact and capacitance sensors was easier to implement. In situations where flows could not be impeded, however, the tomographic approach would likely be more useful. PMID:28025536

  14. Simultaneous Moisture Content and Mass Flow Measurements in Wood Chip Flows Using Coupled Dielectric and Impact Sensors.

    PubMed

    Pan, Pengmin; McDonald, Timothy; Fulton, John; Via, Brian; Hung, John

    2016-12-23

    An 8-electrode capacitance tomography (ECT) sensor was built and used to measure moisture content (MC) and mass flow of pine chip flows. The device was capable of directly measuring total water quantity in a sample but was sensitive to both dry matter and moisture, and therefore required a second measurement of mass flow to calculate MC. Two means of calculating the mass flow were used: the first being an impact sensor to measure total mass flow, and the second a volumetric approach based on measuring total area occupied by wood in images generated using the capacitance sensor's tomographic mode. Tests were made on 109 groups of wood chips ranging in moisture content from 14% to 120% (dry basis) and wet weight of 280 to 1100 g. Sixty groups were randomly selected as a calibration set, and the remaining were used for validation of the sensor's performance. For the combined capacitance/force transducer system, root mean square errors of prediction (RMSEP) for wet mass flow and moisture content were 13.42% and 16.61%, respectively. RMSEP using the combined volumetric mass flow/capacitance sensor for dry mass flow and moisture content were 22.89% and 24.16%, respectively. Either of the approaches was concluded to be feasible for prediction of moisture content in pine chip flows, but combining the impact and capacitance sensors was easier to implement. In situations where flows could not be impeded, however, the tomographic approach would likely be more useful.

  15. Guarded capacitance probes for measuring particle concentration and flow

    DOEpatents

    Louge, M.Y.

    1995-10-17

    Guarded capacitance probe structures are constructed with guard electrodes surrounding one or more sensor electrodes and ground electrodes or grounded surfaces surrounding the guard electrodes. In a one sensor embodiment, the probe utilizes an apertured sensor electrode and the guard electrode both surrounds the sensor electrode and fills the aperture. This embodiment is particularly useful for measuring particle concentration in a fluid suspension contained within a vessel or pipe. The portion of the guard electrode within the aperture of the sensor electrode prevents electric field lines from emanating from the sensor electrode into the fluid suspension and toward infinity. A two sensor embodiment of the probe is useful for measuring flow velocities of fluid suspensions through cross correlation of the outputs generated by each sensor. The relative dimensions of the guard and sensor electrodes are selected to provide the most accurate measurements by confining the electric lines emanating from the sensor electrode or electrodes and terminating on the surrounding grounded surfaces to a small measurement volume of the fluid suspension near the vessel or pipe wall. 14 figs.

  16. Guarded capacitance probes for measuring particle concentration and flow

    DOEpatents

    Louge, Michel Y.

    1995-01-01

    Guarded capacitance probe structures are constructed with guard electrodes surrounding one or more sensor electrodes and ground electrodes or grounded surfaces surrounding the guard electrodes. In a one sensor embodiment, the probe utilizes an apertured sensor electrode and the guard electrode both surrounds the sensor electrode and fills the aperture. This embodiment is particularly useful for measuring particle concentration in a fluid suspension contained within a vessel or pipe. The portion of the guard electrode within the aperture of the sensor electrode prevents electric field lines from emanating from the sensor electrode into the fluid suspension and toward infinity. A two sensor embodiment of the probe is useful for measuring flow velocities of fluid suspensions through cross correlation of the outputs generated by each sensor. The relative dimensions of the guard and sensor electrodes are selected to provide the most accurate measurements by confining the electric lines emanating from the sensor electrode or electrodes and terminating on the surrounding grounded surfaces to a small measurement volume of the fluid suspension near the vessel or pipe wall.

  17. Guarded capacitance probes for measuring particle concentration and flow

    DOEpatents

    Louge, Michel Y.

    1996-01-01

    Guarded capacitance probe structures are constructed with guard electrodes surrounding one or more sensor electrodes and ground electrodes or grounded surfaces surrounding the guard electrodes. In a one sensor embodiment, the probe utilizes an apertured sensor electrode and the guard electrode both surrounds the sensor electrode and fills the aperture. This embodiment is particularly useful for measuring particle concentration in a fluid suspension contained within a vessel or pipe. The portion of the guard electrode within the aperture of the sensor electrode prevents electric field lines from emanating from the sensor electrode into the fluid suspension and toward infinity. A two sensor embodiment of the probe is useful for measuring flow velocities of fluid suspensions through cross correlation of the outputs generated by each sensor. The relative dimensions of the guard and sensor electrodes are selected to provide the most accurate measurements by confining the electric lines emanating from the sensor electrode or electrodes and terminating on the surrounding grounded surfaces to a small measurement volume of the fluid suspension near the vessel or pipe wall.

  18. Guarded capacitance probes for measuring particle concentration and flow

    DOEpatents

    Louge, M.Y.

    1996-08-13

    Guarded capacitance probe structures are constructed with guard electrodes surrounding one or more sensor electrodes and ground electrodes or grounded surfaces surrounding the guard electrodes. In a one sensor embodiment, the probe utilizes an apertured sensor electrode and the guard electrode both surrounds the sensor electrode and fills the aperture. This embodiment is particularly useful for measuring particle concentration in a fluid suspension contained within a vessel or pipe. The portion of the guard electrode within the aperture of the sensor electrode prevents electric field lines from emanating from the sensor electrode into the fluid suspension and toward infinity. A two sensor embodiment of the probe is useful for measuring flow velocities of fluid suspensions through cross correlation of the outputs generated by each sensor. The relative dimensions of the guard and sensor electrodes are selected to provide the most accurate measurements by confining the electric lines emanating from the sensor electrode or electrodes and terminating on the surrounding grounded surfaces to a small measurement volume of the fluid suspension near the vessel or pipe wall. 14 figs.

  19. Centromeric index measurement by slit-scan flow cytometry

    SciTech Connect

    Lucas, J.N.; Gray, J.W.; Peters, D.C.; Van Dilla, M.A.

    1983-01-01

    A report is given of the application of slit-scan flow cytometry (SSFCM) in the classification of muntjac, Chinese hamster, and human chromosomes according to centromeric index (CI) and total fluorescence. Chromosomes were isolated from mitotic cells, stained with propidium iodide and processed through the SSFCM where fluorescence profiles were measured. The centromere for each profile was taken as the point of maximum difference between the measured profile and a standard profile having no centromeric dip. The areas under the profile on either side of the centromere were then calculated and the CI was calculated as the ratio of the larger area to the total area under the profile. Relative DNA contents for each chromosome were taken to be proportional to the total fluorescence. Mean CI's for muntjac chromosomes 1, 2, and X + 3 were 0.52, 0.88, and 0.73, respectively; CI's for Chinese hamster M3-1 chromosomes 1, 2, 5, 8, and M2 were 0.53, 0.55, 0.57, 0.77, and 0.86, respectively; and average CI's for chromosome groups 4 + t (X;5), 6 + 7 + Y, 9 + M1, and 10 + 11 were 0.56, 0.82, 0.58, and 0.60, respectively. These results were, on average, within 4.4% of CI measurements made by image cytometry. CI's measured for human chromosomes 9 through 12, were, on average, within 2.0% of those made by image cytometry.

  20. Active Flow Control Strategies Using Surface Pressure Measurements

    NASA Technical Reports Server (NTRS)

    Kumar, Vikas; Alvi, Farrukh S.

    2010-01-01

    Evaluate the efficacy of Microjets Can we eliminate/minimize flow separation? Is the flow unsteadiness reduced? Guidelines for an active control Search for an appropriate sensor. Examine for means to develop a flow model for identifying the state of flow over the surface Guidelines toward future development of a Simple and Robust control methodology

  1. Momentum Flux Measuring Instrument for Neutral and Charged Particle Flows

    NASA Technical Reports Server (NTRS)

    Chavers, Greg; Chang-Diaz, Franklin; Schafer, Charles F. (Technical Monitor)

    2002-01-01

    An instrument to measure the momentum flux (total pressure) of plasma and neutral particle jets onto a surface has been developed. While this instrument was developed for magnetized plasmas, the concept works for non-magnetized plasmas as well. We have measured forces as small as 10(exp -4) Newtons on a surface immersed in the plasma where small forces are due to ionic and neutral particles with kinetic energies on the order of a few eV impacting the surface. This instrument, a force sensor, uses a target plate (surface) that is immersed in the plasma and connected to one end of an alumina rod while the opposite end of the alumina rod is mechanically connected to a titanium beam on which four strain gauges are mounted. The force on the target generates torque causing strain in the beam. The resulting strain measurements can be correlated to a force on the target plate. The alumina rod electrically and thermally isolates the target plate from the strain gauge beam and allows the strain gauges to be located out of the plasma flow while also serving as a moment arm of several inches to increase the strain in the beam at the strain gauge location. These force measurements correspond directly to momentum flux and may be used with known plasma conditions to place boundaries on the kinetic energies of the plasma and neutral particles. The force measurements may also be used to infer thrust produced by a plasma propulsive device. Stainless steel, titanium, molybdenum, and aluminum flat target plates have been used. Momentum flux measurements of H2, D2, He, and Ar plasmas produced in a magnetized plasma device have been performed.

  2. In vitro measurements of flow using multislice computed tomography (MSCT).

    PubMed

    Lackner, Klaus; Bovenschulte, Henning; Stützer, Hartmut; Just, Thomas; Al-Hassani, Hassan; Krug, Barbara

    2011-07-01

    To examine in vitro whether an assessment of flow in normal and obstructed vessels is essentially possible using modern multislice CT-scanners. An experimental model allowed known stenoses to be perfused at defined flow rates. Aorta and coronary arteries were simulated by silicone tubes. A pulsatile pump was used to perfuse water through the system with intermittent injection of a bolus of radio-opaque contrast agent. CT-measurements were carried out with slice orientation perpendicular to the tubes. 50-90% concentric stenoses were examined 5 times at 4 different stenosis slice distances. A mathematical algorithm calculated the temporal density changes within a ROI in the tube cross-sections. Quantitative assessment of the data simultaneously acquired with the 16-slice system for the "coronary" and "aortal" time-density curves showed that the model allowed for exclusion of a ≥ 80% stenosis grade with a 99% probability when the slopes of the density increase quotient was > 0.79; a stenosis grade of ≥ 90% could be excluded when the slopes of the density increase quotient was > 0.52. A Quotient > 0.94 for "peak density" was associated with a 99% probability of a stenosis grade ≥ 70%. The 64-slice system allowed stenosis grades of ≥ 80% to be discriminated from lower grades. The general feasibility of the in vitro approach was verified in an in vivo model. The spatial, contrast and temporal resolution of CT scanners with at least 16 detector rows enables qualitative and semiquantitative assessment of stenotic changes in flow.

  3. Acute Increase in Hepatic Arterial Flow During TIPS Identified by Intravascular Flow Measurements

    SciTech Connect

    Radeleff, Boris Sommer, Christof-Matthias; Heye, Tobias; Lopez-Benitez, Ruben; Sauer, Peter; Schmidt, Jan; Kauczor, Haus-Ulrich; Richter, Goetz Martin

    2009-01-15

    The purpose of this study was to investigate alterations of hepatic arterial flow during transjugular intrahepatic portosystemic stent shunt (TIPS) applying intravascular Doppler sonography. This prospective monocenter study included 25 patients with liver cirrhosis (alcohol induced [n = 19], chronic hepatitis associated [n = 3], primary biliary cirrhosis associated [n = 1], and cryptogenic [n = 2]) successfully treated with TIPS. All patients underwent intravascular hepatic arterial flow measurements during TIPS using an endoluminal flow sensor. The average arterial peak velocity (APV) and the maximum arterial peak velocity (MPV) were registered. Twenty-two patients (88%) showed increased APV, one patient (4%) showed unaffected APV, and two patients (8%) showed decreased APV after TIPS. The average portosystemic pressure gradient decreased significantly, from 22.0 {+-} 5.1 mmHg before TIPS to 11.0 {+-} 4.1 mmHg after TIPS (-50.0%; p < 0.0001). The average APV increased significantly, from 41.9 {+-} 17.8 cm/s before TIPS to 60.7 {+-} 19.0 cm/s after TIPS (+44.9%; p < 0.0001). The average MPV increased significantly, from 90.8 {+-} 31.7 cm/s before TIPS to 112.6 {+-} 34.9 cm/s after TIPS (+24.0%; p = 0.0002). These changes in perfusion set in within seconds after TIPS tract formation in all the patients with increased APV. We conclude that TIPS-induced portosystemic decompression leads to a significant increase in hepatic arterial flow. The changes occurred within seconds, suggesting a reflex-like mechanism.

  4. 21 CFR 876.1800 - Urine flow or volume measuring system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Urine flow or volume measuring system. 876.1800... (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1800 Urine flow or volume measuring system. (a) Identification. A urine flow or volume measuring system is a device...

  5. 21 CFR 876.1800 - Urine flow or volume measuring system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Urine flow or volume measuring system. 876.1800... (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1800 Urine flow or volume measuring system. (a) Identification. A urine flow or volume measuring system is a device...

  6. 21 CFR 876.1800 - Urine flow or volume measuring system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Urine flow or volume measuring system. 876.1800... (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1800 Urine flow or volume measuring system. (a) Identification. A urine flow or volume measuring system is a device...

  7. 21 CFR 876.1800 - Urine flow or volume measuring system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Urine flow or volume measuring system. 876.1800... (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1800 Urine flow or volume measuring system. (a) Identification. A urine flow or volume measuring system is a device...

  8. Turbulence Measurements of Separate Flow Nozzles with Mixing Enhancement Features

    NASA Technical Reports Server (NTRS)

    Bridges, James; Wernet, Mark P.

    2002-01-01

    Comparison of turbulence data taken in three separate flow nozzles, two with mixing enhancement features on their core nozzle, shows how the mixing enhancement features modify turbulence to reduce jet noise. The three nozzles measured were the baseline axisymmetric nozzle 3BB, the alternating chevron nozzle, 3A12B, with 6-fold symmetry, and the flipper tab nozzle 3T24B also with 6-fold symmetry. The data presented show the differences in turbulence characteristics produced by the geometric differences in the nozzles, with emphasis on those characteristics of interest in jet noise. Among the significant findings: the enhanced mixing devices reduce turbulence in the jet mixing region while increasing it in the fan/core shear layer, the ratios of turbulence components are significantly altered by the mixing devices, and the integral lengthscales do not conform to any turbulence model yet proposed. These findings should provide guidance for modeling the statistical properties of turbulence to improve jet noise prediction.

  9. Thermomolecular effect on pressure measurements with orifices in transitional flow

    NASA Technical Reports Server (NTRS)

    Potter, J. L.; Blanchard, Robert C.

    1991-01-01

    Results are presented of a study carried out in order to verify a version of the method (presented at the 7th International Rarefied Gas Dynamics Symposium) for calculating the influence of thermomolecular flow on the pressures measured by means of orifices in walls exposed to rarefied gases. In these experiments, the 'orifice effect' is examined under conditions that are significantly different from those for which the semiempirical (SE) method of Kinslow and Potter (1971) was shown to be successful. Comparisons between the predicted results with flight data and the results obtained in the laboratory, combined with limited DSMC calculations, indicate that the SE method remains a useful tool which is relatively easy to apply and which gives good results when an appropriate energy accommodation coefficient is used.

  10. Simultaneous drag and flow measurements of Olympic skeleton athletes

    NASA Astrophysics Data System (ADS)

    Moon, Yae Eun; Digiulio, David; Peters, Steve; Wei, Timothy

    2009-11-01

    The Olympic sport of skeleton involves an athlete riding a small sled face first down a bobsled track at speeds up to 130 km/hr. In these races, the difference between gold and missing the medal stand altogether can be hundredths of a second per run. As such, reducing aerodynamic drag through proper body positioning is of first order importance. To better study the flow behavior and to improve the performance of the athletes, we constructed a static force balance system on a mock section of a bobsled track. Athlete and the sled are placed on the force balance system which is positioned at the exit of an open loop wind tunnel. Simultaneous drag force and DPIV velocity field measurements were made along with video recordings of body position to aid the athletes in determining their optimal aerodynamic body position.

  11. Electrophysiological measurement of information flow during visual search.

    PubMed

    Cosman, Joshua D; Arita, Jason T; Ianni, Julianna D; Woodman, Geoffrey F

    2016-04-01

    The temporal relationship between different stages of cognitive processing is long debated. This debate is ongoing, primarily because it is often difficult to measure the time course of multiple cognitive processes simultaneously. We employed a manipulation that allowed us to isolate ERP components related to perceptual processing, working memory, and response preparation, and then examined the temporal relationship between these components while observers performed a visual search task. We found that, when response speed and accuracy were equally stressed, our index of perceptual processing ended before both the transfer of information into working memory and response preparation began. However, when we stressed speed over accuracy, response preparation began before the completion of perceptual processing or transfer of information into working memory on trials with the fastest reaction times. These findings show that individuals can control the flow of information transmission between stages, either waiting for perceptual processing to be completed before preparing a response or configuring these stages to overlap in time.

  12. Detailed flow and force measurements in a rotated triangular tube bundle subjected to two-phase cross-flow

    NASA Astrophysics Data System (ADS)

    Pettigrew, M. J.; Zhang, C.; Mureithi, N. W.; Pamfil, D.

    2005-05-01

    Two-phase cross-flow exists in many shell-and-tube heat exchangers. A detailed knowledge of the characteristics of two-phase cross-flow in tube bundles is required to understand and formulate flow-induced vibration parameters such as damping, fluidelastic instability, and random excitation due to turbulence. An experimental program was undertaken with a rotated-triangular array of cylinders subjected to air/water flow to simulate two-phase mixtures. The array is made of relatively large diameter cylinders (38 mm) to allow for detailed two-phase flow measurements between cylinders. Fiber-optic probes were developed to measure local void fraction. Local flow velocities and bubble diameters or characteristic lengths of the two-phase mixture are obtained by using double probes. Both the dynamic lift and drag forces were measured with a strain gauge instrumented cylinder.

  13. Differential Effects of Heavy Versus Moderate Loads on Measures of Strength and Hypertrophy in Resistance-Trained Men.

    PubMed

    Schoenfeld, Brad J; Contreras, Bret; Vigotsky, Andrew D; Peterson, Mark

    2016-12-01

    The purpose of the present study was to evaluate muscular adaptations between heavy- and moderate-load resistance training (RT) with all other variables controlled between conditions. Nineteen resistance-trained men were randomly assigned to either a strength-type RT routine (HEAVY) that trained in a loading range of 2-4 repetitions per set (n = 10) or a hypertrophy-type RT routine (MODERATE) that trained in a loading range of 8-12 repetitions per set (n = 9). Training was carried out 3 days a week for 8 weeks. Both groups performed 3 sets of 7 exercises for the major muscle groups of the upper and lower body. Subjects were tested pre- and post-study for: 1 repetition maximum (RM) strength in the bench press and squat, upper body muscle endurance, and muscle thickness of the elbow flexors, elbow extensors, and lateral thigh. Results showed statistically greater increases in 1RM squat strength favoring HEAVY compared to MODERATE. Alternatively, statistically greater increases in lateral thigh muscle thickness were noted for MODERATE versus HEAVY. These findings indicate that heavy load training is superior for maximal strength goals while moderate load training is more suited to hypertrophy-related goals when an equal number of sets are performed between conditions.

  14. Validity of the New Lifestyles NL-1000 Accelerometer for Measuring Time Spent in Moderate-to-Vigorous Physical Activity in School Settings

    ERIC Educational Resources Information Center

    McMinn, David; Rowe, David A.; Stark, Michelle; Nicol, Louise

    2010-01-01

    Current interest in promoting physical activity in the school environment necessitates an inexpensive, accurate method of measuring physical activity in such settings. Additionally, it is recognized that physical activity must be of at least moderate intensity in order to yield substantial health benefits. The purpose of the study, therefore, was…

  15. Self-contained Tubular Compressed-flow Generation Device for Use in Making Differential Measurements

    NASA Technical Reports Server (NTRS)

    England, John D. (Inventor); Kelley, Anthony R. (Inventor); Cronise, Raymond J. (Inventor)

    2013-01-01

    A device used in making differential measurements of a flow includes an open-ended tubular flow obstruction and a support arm. The flow obstruction has an outer annular wall and an inner annular wall. The support arm has a first end coupled to an exterior wall of a conduit and a second end coupled to the flow obstruction. The support arm positions the flow obstruction in the conduit such that a first flow region is defined around the flow obstruction's outer annular wall and a second flow region is defined by the flow obstruction's inner annular wall. The support arm's first end and second end are separated from one another with respect to a length dimension of the conduit. Measurement ports provided in the flow obstruction are coupled to points at the exterior wall of the conduit by manifolds extending through the flow obstruction and support arm.

  16. Differential Effects of Heavy Versus Moderate Loads on Measures of Strength and Hypertrophy in Resistance-Trained Men

    PubMed Central

    Schoenfeld, Brad J.; Contreras, Bret; Vigotsky, Andrew D.; Peterson, Mark

    2016-01-01

    The purpose of the present study was to evaluate muscular adaptations between heavy- and moderate-load resistance training (RT) with all other variables controlled between conditions. Nineteen resistance-trained men were randomly assigned to either a strength-type RT routine (HEAVY) that trained in a loading range of 2-4 repetitions per set (n = 10) or a hypertrophy-type RT routine (MODERATE) that trained in a loading range of 8-12 repetitions per set (n = 9). Training was carried out 3 days a week for 8 weeks. Both groups performed 3 sets of 7 exercises for the major muscle groups of the upper and lower body. Subjects were tested pre- and post-study for: 1 repetition maximum (RM) strength in the bench press and squat, upper body muscle endurance, and muscle thickness of the elbow flexors, elbow extensors, and lateral thigh. Results showed statistically greater increases in 1RM squat strength favoring HEAVY compared to MODERATE. Alternatively, statistically greater increases in lateral thigh muscle thickness were noted for MODERATE versus HEAVY. These findings indicate that heavy load training is superior for maximal strength goals while moderate load training is more suited to hypertrophy-related goals when an equal number of sets are performed between conditions. Key points Heavy loads maximize muscular strength when the numbers of sets are equated. Moderate loads maximize muscle hypertrophy when the number of sets are equated Volume load appears to be more important to increases in muscle hypertrophy compared to absolute strength PMID:27928218

  17. MEASUREMENTS AND COMPUTATIONS OF FUEL DROPLET TRANSPORT IN TURBULENT FLOWS

    SciTech Connect

    Joseph Katz and Omar Knio

    2007-01-10

    The objective of this project is to study the dynamics of fuel droplets in turbulent water flows. The results are essential for development of models capable of predicting the dispersion of slightly light/heavy droplets in isotropic turbulence. Since we presently do not have any experimental data on turbulent diffusion of droplets, existing mixing models have no physical foundations. Such fundamental knowledge is essential for understanding/modeling the environmental problems associated with water-fuel mixing, and/or industrial processes involving mixing of immiscible fluids. The project has had experimental and numerical components: 1. The experimental part of the project has had two components. The first involves measurements of the lift and drag forces acting on a droplet being entrained by a vortex. The experiments and data analysis associated with this phase are still in progress, and the facility, constructed specifically for this project is described in Section 3. In the second and main part, measurements of fuel droplet dispersion rates have been performed in a special facility with controlled isotropic turbulence. As discussed in detail in Section 2, quantifying and modeling the of droplet dispersion rate requires measurements of their three dimensional trajectories in turbulent flows. To obtain the required data, we have introduced a new technique - high-speed, digital Holographic Particle Image Velocimetry (HPIV). The technique, experimental setup and results are presented in Section 2. Further information is available in Gopalan et al. (2005, 2006). 2. The objectives of the numerical part are: (1) to develop a computational code that combines DNS of isotropic turbulence with Lagrangian tracking of particles based on integration of a dynamical equation of motion that accounts for pressure, added mass, lift and drag forces, (2) to perform extensive computations of both buoyant (bubbles) and slightly buoyant (droplets) particles in turbulence conditions

  18. Minimally destructive Doppler measurement of a quantized, superfluid flow

    NASA Astrophysics Data System (ADS)

    Anderson, Neil; Kumar, Avinash; Eckel, Stephen; Stringari, Sandro; Campbell, Gretchen

    2016-05-01

    Ring shaped Bose-Einstein condensates are of interest because they support the existence of quantized, persistent currents. These currents arise because in a ring trap, the wavefunction of the condensate must be single valued, and thus the azimuthal velocity is quantized. Previously, these persistent current states have only been measured in a destructive fashion via either interference with a phase reference or using the size of a central vortex-like structure that appears in time of flight. Here, we demonstrate a minimally destructive, in-situ measurement of the winding number of a ring shaped BEC. We excite a standing wave of phonon modes in the ring BEC using a perturbation. If the condensate is in a nonzero circulation state, then the frequency of these phonon modes are Doppler shifted, causing the standing wave to precess about the ring. From the direction and velocity of this precession, we can infer the winding number of the flow. For certain parameters, this technique can detect individual winding numbers with approximately 90% fidelity.

  19. MEASURING THE GALAXY CLUSTER BULK FLOW FROM WMAP DATA

    SciTech Connect

    Osborne, S. J.; Church, S. E.; Mak, D. S. Y.; Pierpaoli, E.

    2011-08-20

    We have looked for bulk motions of galaxy clusters in the Wilkinson Microwave Anisotropy Probe (WMAP) seven-year data. We isolate the kinetic Sunyaev-Zeldovich (SZ) signal by filtering the WMAP Q-, V-, and W-band maps with multi-frequency matched filters that utilize the spatial properties of the kinetic SZ signal to optimize detection. We try two filters: a filter that has no spectral dependence, and a filter that utilizes the spectral properties of the kinetic and thermal SZ signals to remove the thermal SZ bias. We measure the monopole and dipole spherical harmonic coefficients of the kinetic SZ signal, as well as the l = 2-5 modes, at the locations of 736 ROSAT observed galaxy clusters. We find no significant power in the kinetic SZ signal at these multipoles with either filter, consistent with the {Lambda}CDM prediction. Our limits are a factor of {approx}3 more sensitive than the claimed bulk flow detection of Kashlinsky et al. Using simulations we estimate that in maps filtered by our matched filter with no spectral dependence there is a thermal SZ dipole that would be mistakenly measured as a bulk motion of {approx}2000-4000 km s{sup -1}. For the WMAP data, the signal-to-noise ratio obtained with the unbiased filter is almost an order of magnitude lower.

  20. Multidirectional plasma flow measurement by Gundestrup Probe in scrape-off layer of ADITYA tokamak

    SciTech Connect

    Sangwan, Deepak; Jha, Ratneshwar; Tanna, Rakesh L.

    2015-11-15

    Multidirectional plasma flow measurements by using Gundestrup Probe in the scrape-off layer of ADITYA tokamak are presented. The ADITYA Gundestrup Probe-head consists of eight plates arranged around the ceramic rod and three pins normal to side plates. Plates are used to measure both parallel and perpendicular flows simultaneously and pins are used to measure plasma density and floating potential. A comparison of direct perpendicular flow measurement and by two other plates of Gundestrup Probe is presented. Possible causes of perpendicular flows are identified and compared with the measured flows. It is observed that the mechanism of the parallel flow and the perpendicular flow is different only at high parallel Mach number. A puff of the working gas is used to study its effect on the perpendicular flows and its reversal with the gas puff is observed.

  1. Observations of debris flows at Chalk Cliffs, Colorado, USA: Part 1, in-situ measurements of flow dynamics, tracer particle movement and video imagery from the summer of 2009

    USGS Publications Warehouse

    McCoy, Scott W.; Coe, Jeffrey A.; Kean, Jason W.; Tucker, Greg E.; Staley, Dennis M.; Wasklewicz, Thad A.

    2011-01-01

    Debris flows initiated by surface-water runoff during short duration, moderate- to high-intensity rainfall are common in steep, rocky, and sparsely vegetated terrain. Yet large uncertainties remain about the potential for a flow to grow through entrainment of loose debris, which make formulation of accurate mechanical models of debris-flow routing difficult. Using a combination of in situ measurements of debris flow dynamics, video imagery, tracer rocks implanted with passive integrated transponders (PIT) and pre- and post-flow 2-cm resolution digital terrain models (terrain data presented in a companion paper by STALEY et alii, 2011), we investigated the entrainment and transport response of debris flows at Chalk Cliffs, CO, USA. Four monitored events during the summer of 2009 all initiated from surface-water runoff, generally less than an hour after the first measurable rain. Despite reach-scale morphology that remained relatively constant, the four flow events displayed a range of responses, from long-runout flows that entrained significant amounts of channel sediment and dammed the main-stem river, to smaller, short-runout flows that were primarily depositional in the upper basin. Tracer-rock travel-distance distributions for these events were bimodal; particles either remained immobile or they travelled the entire length of the catchment. The long-runout, large-entrainment flow differed from the other smaller flows by the following controlling factors: peak 10-minute rain intensity; duration of significant flow in the channel; and to a lesser extent, peak surge depth and velocity. Our growing database of natural debris-flow events can be used to develop linkages between observed debris-flow transport and entrainment responses and the controlling rainstorm characteristics and flow properties.

  2. Oscillatory motion based measurement method and sensor for measuring wall shear stress due to fluid flow

    DOEpatents

    Armstrong, William D.; Naughton, Jonathan; Lindberg, William R.

    2008-09-02

    A shear stress sensor for measuring fluid wall shear stress on a test surface is provided. The wall shear stress sensor is comprised of an active sensing surface and a sensor body. An elastic mechanism mounted between the active sensing surface and the sensor body allows movement between the active sensing surface and the sensor body. A driving mechanism forces the shear stress sensor to oscillate. A measuring mechanism measures displacement of the active sensing surface relative to the sensor body. The sensor may be operated under periodic excitation where changes in the nature of the fluid properties or the fluid flow over the sensor measurably changes the amplitude or phase of the motion of the active sensing surface, or changes the force and power required from a control system in order to maintain constant motion. The device may be operated under non-periodic excitation where changes in the nature of the fluid properties or the fluid flow over the sensor change the transient motion of the active sensor surface or change the force and power required from a control system to maintain a specified transient motion of the active sensor surface.

  3. Measurement and modeling of coronary blood flow.

    PubMed

    Sinclair, Matthew D; Lee, Jack; Cookson, Andrew N; Rivolo, Simone; Hyde, Eoin R; Smith, Nicolas P

    2015-01-01

    Ischemic heart disease that comprises both coronary artery disease and microvascular disease is the single greatest cause of death globally. In this context, enhancing our understanding of the interaction of coronary structure and function is not only fundamental for advancing basic physiology but also crucial for identifying new targets for treating these diseases. A central challenge for understanding coronary blood flow is that coronary structure and function exhibit different behaviors across a range of spatial and temporal scales. While experimental studies have sought to understand this feature by isolating specific mechanisms, in tandem, computational modeling is increasingly also providing a unique framework to integrate mechanistic behaviors across different scales. In addition, clinical methods for assessing coronary disease severity are continuously being informed and updated by findings in basic physiology. Coupling these technologies, computational modeling of the coronary circulation is emerging as a bridge between the experimental and clinical domains, providing a framework to integrate imaging and measurements from multiple sources with mathematical descriptions of governing physical laws. State-of-the-art computational modeling is being used to combine mechanistic models with data to provide new insight into coronary physiology, optimization of medical technologies, and new applications to guide clinical practice.

  4. Direct measurement of floc breakage in flowing suspensions

    SciTech Connect

    Peng, S.J.; Williams, R.A. . Camborne School of Mines)

    1994-09-01

    Direct measurements of floc breakage behavior of silica and latex dispersions in a stirred tank and process pipeline have been performed using in situ scanning laser microscopy. The results show the effect of agitation intensity, flocculant dosage, and solids concentration on the floc formation and breakup in a stirred tanks. The effect of the rms velocity gradients on the floc breakage behavior in a process pipeline is also demonstrated and modeled using a quantitative relationship between the breakage constant (K) and the rms velocity gradient (G). These data provide a means of assessing, quantitatively, the strength of a floc population. Expressions for the mean dimensionless floc size R (scaled to the mean diameter of the primary particles) have been obtained for polymer-flocculated suspensions flowing in tubes. Typically R is given by (1 + aG[sup b]), where a and b depend on the volume concentration of solids. For 0.5% solids, a = 34.7, b = [minus]0.67; for 1.0% solids, a = 4.85, b= [minus]0.29.

  5. Electrophysiological measurement of information flow during visual search

    PubMed Central

    Cosman, Joshua D.; Arita, Jason T.; Ianni, Julianna D.; Woodman, Geoffrey F.

    2016-01-01

    The temporal relationship between different stages of cognitive processing is long-debated. This debate is ongoing, primarily because it is often difficult to measure the time course of multiple cognitive processes simultaneously. We employed a manipulation that allowed us to isolate ERP components related to perceptual processing, working memory, and response preparation, and then examined the temporal relationship between these components while observers performed a visual search task. We found that when response speed and accuracy were equally stressed, our index of perceptual processing ended before both the transfer of information into working memory and response preparation began. However, when we stressed speed over accuracy response preparation began before the completion of perceptual processing or transfer of information into working memory on trials with the fastest reaction times. These findings show that individuals can control the flow of information transmission between stages, either waiting for perceptual processing to be completed before preparing a response or configuring these stages to overlap in time. PMID:26669285

  6. Visual Measurements of Droplet Size in Gas Liquid Annular Flow

    SciTech Connect

    Fore, L.B.; Ibrahim, B.B.; Beus, S.G.

    2000-07-01

    Drop size distributions have been measured for nitrogen-water annular flow in a 9.67 mm hydraulic diameter duct, at system pressures of 3.4 and 17 atm and a temperature of 38 C. These new data extend the range of conditions represented by existing data in the open literature, primarily through an increase in system pressure. Since most existing correlations were developed from data obtained at lower pressures, it should be expected that the higher-pressure data presented in this paper would not necessarily follow those correlations. The correlation of Tatterson, et al. (1977) does not predict the new data very well, while the correlation of Kataoka, et al. (1983) only predicts those data taken at the lower pressure of 3.4 atm. However, the maximum drop size correlation of Kocamustafaogullari, et al. (1994) does predict the current data to a reasonable approximation. Similarly, their correlation for the Sauter mean diameter can predict the new data, provided the coefficient in the equation is adjusted.

  7. Ultrasonic Doppler measurement of renal artery blood flow

    NASA Technical Reports Server (NTRS)

    Freund, W. R.; Beaver, W. L.; Meindl, J. D.

    1976-01-01

    Studies were made of (1) blood flow redistribution during lower body negative pressure (LBNP), (2) the profile of blood flow across the mitral annulus of the heart (both perpendicular and parallel to the commissures), (3) testing and evaluation of a number of pulsed Doppler systems, (4) acute calibration of perivascular Doppler transducers, (5) redesign of the mitral flow transducers to improve reliability and ease of construction, and (6) a frequency offset generator designed for use in distinguishing forward and reverse components of blood flow by producing frequencies above and below the offset frequency. Finally methodology was developed and initial results were obtained from a computer analysis of time-varying Doppler spectra.

  8. New sensor for measurement of low air flow velocity. Phase I final report

    SciTech Connect

    Hashemian, H.M.; Hashemian, M.; Riggsbee, E.T.

    1995-08-01

    The project described here is the Phase I feasibility study of a two-phase program to integrate existing technologies to provide a system for determining air flow velocity and direction in radiation work areas. Basically, a low air flow sensor referred to as a thermocouple flow sensor has been developed. The sensor uses a thermocouple as its sensing element. The response time of the thermocouple is measured using an existing in-situ method called the Loop Current Step Response (LCSR) test. The response time results are then converted to a flow signal using a response time-versus-flow correlation. The Phase I effort has shown that a strong correlation exists between the response time of small diameter thermocouples and the ambient flow rate. As such, it has been demonstrated that thermocouple flow sensors can be used successfully to measure low air flow rates that can not be measured with conventional flow sensors. While the thermocouple flow sensor developed in this project was very successful in determining air flow velocity, determining air flow direction was beyond the scope of the Phase I project. Nevertheless, work was performed during Phase I to determine how the new flow sensor can be used to determine the direction, as well as the velocity, of ambient air movements. Basically, it is necessary to use either multiple flow sensors or move a single sensor in the monitoring area and make flow measurements at various locations sweeping the area from top to bottom and from left to right. The results can then be used with empirical or physical models, or in terms of directional vectors to estimate air flow patterns. The measurements can be made continuously or periodically to update the flow patterns as they change when people and objects are moved in the monitoring area. The potential for using multiple thermocouple flow sensors for determining air flow patterns will be examined in Phase II.

  9. An α-synuclein gene (SNCA) polymorphism moderates the association of PTSD symptomatology with hazardous alcohol use, but not with aggression-related measures.

    PubMed

    Guillot, Casey R; Fanning, Jennifer R; Liang, Tiebing; Leventhal, Adam M; Berman, Mitchell E

    2015-03-01

    Posttraumatic stress disorder (PTSD) often precedes comorbid substance use disorder and has been associated with aggression. Prior research has evidenced that alcohol use and other externalizing behaviors share genetic factors with PTSD; however, few studies have examined if specific genes are associated with externalizing behaviors in PTSD. The purpose of the current study was to investigate whether an α-synuclein gene polymorphism (SNCA rs356195) moderates the association of PTSD symptomatology with externalizing behaviors. We examined the separate and combined effects of PTSD symptomatology and SNCA rs356195 on alcohol- and aggression-related measures in nonclinical participants (N=138 European Americans; 15 diagnosed with probable PTSD). Probable PTSD status and SNCA were both associated with externalizing measures. SNCA also moderated the association of PTSD symptomatology with hazardous alcohol use, but not with aggression-related measures. Current findings suggest that variations in SNCA may increase the likelihood that PTSD symptomatology results in excessive alcohol use.

  10. Regional gastric mucosal blood flow measurements by hydrogen gas clearance in the anesthetized rat and rabbit.

    PubMed

    Leung, F W; Guth, P H; Scremin, O U; Golanska, E M; Kauffman, G L

    1984-07-01

    Hydrogen gas clearance using 3% hydrogen in air and platinum contact electrodes was employed for measuring antral and corpus mucosal blood flow in anesthetized animals. Significantly greater antral than corpus mucosal blood flow was consistently demonstrated. Corpus but not antral mucosal blood flow showed a significant dose-related increase with intravenous pentagastrin. Vasopressin induced a significant dose-related decrease in both antral and corpus mucosal blood flow. Simultaneous measurement of basal corpus mucosal blood flow by hydrogen gas clearance and of gastric mucosal blood flow by aminopyrine clearance gave similar values, but the changes with intravenous pentagastrin or vasopressin measured by aminopyrine clearance were of a much higher order of magnitude. Hydrogen gas clearance, however, reflected changes in left gastric artery blood flow much more closely than did aminopyrine clearance. Therefore, we conclude that the hydrogen gas clearance technique as described is valid for measuring regional gastric mucosal blood flow. It is safe and has potential application in human studies.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27377852

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    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.

  13. Measurements of inlet flow distortions in an axial flow fan (6 and 9 blade rotor)

    NASA Technical Reports Server (NTRS)

    Barr, L. C.

    1978-01-01

    A large quantity of experimental data on inlet flow distortions in an axial flow fan were obtained. The purpose of the study was to determine the effects of design and operating variables and the type of distortion on the response of an axial flow turbomachinery rotor. Included are background information and overall trends observed in distortion attenuation and unsteady total pressure losses.

  14. Volumetric intake flow measurements of an IC engine using magnetic resonance velocimetry

    NASA Astrophysics Data System (ADS)

    Freudenhammer, Daniel; Baum, Elias; Peterson, Brian; Böhm, Benjamin; Jung, Bernd; Grundmann, Sven

    2014-05-01

    Magnetic resonance velocimetry (MRV) measurements are performed in a 1:1 scale model of a single-cylinder optical engine to investigate the volumetric flow within the intake and cylinder geometry during flow induction. The model is a steady flow water analogue of the optical IC-engine with a fixed valve lift of mm to simulate the induction flow at crank-angle bTDC. This setup resembles a steady flow engine test bench configuration. MRV measurements are validated with phase-averaged particle image velocimetry (PIV) measurements performed within the symmetry plane of the optical engine. Differences in experimental operating parameters between MRV and PIV measurements are well addressed. Comparison of MRV and PIV measurements is demonstrated using normalized mean velocity component profiles and showed excellent agreement in the upper portion of the cylinder chamber (i.e., mm). MRV measurements are further used to analyze the ensemble average volumetric flow within the 3D engine domain. Measurements are used to describe the 3D overflow and underflow behavior as the annular flow enters the cylinder chamber. Flow features such as the annular jet-like flows extending into the cylinder, their influence on large-scale in-cylinder flow motion, as well as flow recirculation zones are identified in 3D space. Inlet flow velocities are analyzed around the entire valve curtain perimeter to quantify percent mass flow rate entering the cylinder. Recirculation zones associated with the underflow are shown to reduce local mass flow rates up to 50 %. Recirculation zones are further analyzed in 3D space within the intake manifold and cylinder chamber. It is suggested that such recirculation zones can have large implications on cylinder charge filling and variations of the in-cylinder flow pattern. MRV is revealed to be an important diagnostic tool used to understand the volumetric induction flow within engine geometries and is potentially suited to evaluate flow changes due to intake

  15. Chronic intestinal ischaemia: measurement of the total splanchnic blood flow.

    PubMed

    Zacho, Helle D

    2013-04-01

    A redundant collateral network between the intestinal arteries is present at all times. In case of ischaemia in the gastrointestinal tract, the collateral blood supply can develop further, thus accommodating the demand for oxygen even in the presence of significant stenosis or occlusion of the intestinal arteries without clinical symptoms of intestinal ischaemia. Symptoms of ischemia develop when the genuine and collateral blood supply no longer can accommodate the need for oxygen. Atherosclerosis is the most common cause of obliteration in the intestinal arteries. In chronic intestinal ischaemia (CII), the fasting splanchnic blood flow (SBF) is sufficient, but the postprandial increase in SBF is inadequate and abdominal pain will therefore develop in relation to food intake causing the patient to eat smaller meals at larger intervals with a resulting weight loss. Traditionally, the CII-diagnosis has exclusively been based upon morphology (angiography) of the intestinal arteries; however, substantial discrepancies between CII-symptoms and the presence of atherosclerosis/stenosis in the intestinal arteries have been described repeatedly in the literature impeding the diagnosis of CII. This PhD thesis explores a method to determine the total SBF and its potential use as a diagnostic tool in patients suspected to suffer from CII. The SBF can be measured using a continuous infusion of a tracer and catheterisation of a hepatic vein and an artery. By measuring the SBF before and after a standard meal it is possible to assess the ability or inability to enhance the SBF and thereby diagnosing CII. In Study I, measurement of SBF was tested against angiography in a group of patients suspected to suffer from CII due to pain and weight loss. A very good agreement between the postprandial increase in SBF and angiography was found. The method was validated against a well-established method independent of the hepatic extraction of tracer using pAH in a porcine model (study II

  16. Simple Radiowave-Based Method For Measuring Peripheral Blood Flow Project

    NASA Technical Reports Server (NTRS)

    Oliva-Buisson, Yvette J.

    2014-01-01

    Project objective is to design small radio frequency based flow probes for the measurement of blood flow velocity in peripheral arteries such as the femoral artery and middle cerebral artery. The result will be the technological capability to measure peripheral blood flow rates and flow changes during various environmental stressors such as microgravity without contact to the individual being monitored. This technology may also lead to an easier method of detecting venous gas emboli during extravehicular activities.

  17. Doppler Global Velocimetry Measurements of the Vortical Flow Above an F/A-18

    NASA Technical Reports Server (NTRS)

    Lee, Joseph W.; Meyers, James F.; Cavone, Angelo A.; Suzuki, Karen E.

    1993-01-01

    A Doppler global velocimeter was used to investigate the vortical flow above an F/A-18 model at 25-degrees angle of attack. The measurements indicate that the flow had the same characteristics as the vortical flow above a standard delta wing. The flow pattern indicating transition from stable to burst conditions found above the delta wing was also found at the 440 station above the F/A-18. Measurements downstream at the 524 station found that the flow velocity varied considerably, with standard deviations reaching 30 percent of free stream. However, individual data images indicated that the flow was spatially coherent, and not chaotic as expected.

  18. Three Component Doppler Global Velocimeter Measurements of the Flow Above A Delta Wing

    NASA Technical Reports Server (NTRS)

    Meyers, James F.; Lee, Joseph W.; Covone, Angelo A.

    1992-01-01

    A new measurement technique is being developed by NASA to measure off-surface flow fields. This method, Doppler global velocimetry, will allow quantification of complex three-dimensional flow fields at video camera rates. The entire flow field structure within a selected plane is measured simultaneously rather than by scanned, point-by-point measurements using conventional laser velocimetry. To assess the capability of this new technique, three - component velocity measurements of the vortical flow field above a thin 75-degree delta wing were made in the NASA Langley Basic Aerodynamics Research Tunnel. Measurements were made of the flow field at the 70-percent chord location at angles-of-attack of 20.5 and 40.0 degrees to investigate unburst and burst vortices. For comparison, previous fringe-type laser velocimeter measurements of the flow field at the same conditions are included.

  19. Laboratory Evaluation of Air Flow Measurement Methods for Residential HVAC Returns

    SciTech Connect

    Walker, Iain; Stratton, Chris

    2015-07-01

    This project improved the accuracy of air flow measurements used in commissioning California heating and air conditioning systems in Title 24 (Building and Appliance Efficiency Standards), thereby improving system performance and efficiency of California residences. The research team at Lawrence Berkeley National Laboratory addressed the issue that typical tools used by contractors in the field to test air flows may not be accurate enough to measure return flows used in Title 24 applications. The team developed guidance on performance of current diagnostics as well as a draft test method for use in future evaluations. The series of tests performed measured air flow using a range of techniques and devices. The measured air flows were compared to reference air flow measurements using inline air flow meters built into the test apparatus. The experimental results showed that some devices had reasonable results (typical errors of 5 percent or less) but others had much bigger errors (up to 25 percent).

  20. Continuous flow measurements using ultrasonic velocity meters - an update

    USGS Publications Warehouse

    Oltmann, Rick

    1995-01-01

    An article in the summer 1993 Newsletter described USGS work to continously monitor tidal flows in the delta using ultrasonic velocity meters.  This article updates progress since 1993, including new installations, results of data analysis, damage during this year's high flows, and the status of each site.

  1. Poiseuille flow to measure the viscosity of particle model fluids.

    PubMed

    Backer, J A; Lowe, C P; Hoefsloot, H C J; Iedema, P D

    2005-04-15

    The most important property of a fluid is its viscosity, it determines the flow properties. If one simulates a fluid using a particle model, calculating the viscosity accurately is difficult because it is a collective property. In this article we describe a new method that has a better signal to noise ratio than existing methods. It is based on using periodic boundary conditions to simulate counter-flowing Poiseuille flows without the use of explicit boundaries. The viscosity is then related to the mean flow velocity of the two flows. We apply the method to two quite different systems. First, a simple generic fluid model, dissipative particle dynamics, for which accurate values of the viscosity are needed to characterize the model fluid. Second, the more realistic Lennard-Jones fluid. In both cases the values we calculated are consistent with previous work but, for a given simulation time, they are more accurate than those obtained with other methods.

  2. Measurements in a large angle oblique jet impingement flow

    NASA Technical Reports Server (NTRS)

    Foss, J. F.

    1978-01-01

    The flow field associated with the oblique impingement of an axisymmetric jet was investigated in the externally blown flap configuration for the STOL aircraft. The passive and active spreading characteristics of the shallow angle (a greater than or = approximately to 15 degrees) oblique impingement flow, the role of the initially azimuthal vorticity field, and the stagnation point region were studied, and compared to the large ( a = 45 degres) oblique jet impingement flow. A description of the characteristics of the large angle impingement flow is presented: A flow field near the plate as showing two distinct patterns, one near the location of the maximum surface pressure, and another about the geometric intersection of the jet axis with the plate; and turbulence in the region above the plate which is greater than the one accounted for by the convection of turbulence energy by the mean motion.

  3. Validation of thermal techniques for measurement of pelvic organ blood flows in the nonpregnant sheep: comparison with transit-time ultrasonic and microsphere measurements of blood flow

    SciTech Connect

    Randall, N.J.; Beard, R.W.; Sutherland, I.A.; Figueroa, J.P.; Drost, C.J.; Nathanielsz, P.W.

    1988-03-01

    Data obtained from a thermal system capable of measuring changes in organ temperature as well as tissue thermal clearance in the uterus and vagina have been compared with blood flow measured continuously with a transit-time ultrasound volume-flow sensor placed around the common internal iliac artery and intermittently with radioactive microspheres in the chronically instrumented nonpregnant sheep. Temperature changes in both the uterus and the vagina correlated well with blood flow changes measured by both techniques after intravenous administration of estradiol or norepinephrine. Thermal clearance did not correlate well with blood flow in the vagina or uterus. These methods may have value in the investigation of blood flow patterns in various clinical situations such as the pelvic pain syndrome and early pregnancy.

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

    PubMed

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

    2017-02-21

    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.

  5. Fusion Research of Electrical Tomography with Other Sensors for Two-phase Flow Measurement

    NASA Astrophysics Data System (ADS)

    Deng, Xiang; Yang, W. Q.

    2012-01-01

    The two-phase flow widely exists in the nature and industrial processes. The measurement of two-phase flows, including gas/solids, gas/liquid and liquid/liquid flows, is still challenging. Fusions of electrical tomography with conventional sensors provide possibilities to improve two-phase flow accurate measurement. In this paper, fusions of (1) electrical resistance tomography (ERT) with electromagnetic (EM) flowmeter, (2) electrical capacitance tomography (ECT) with ERT and (3) ECT with electrostatic sensor are introduced. Some research results of fusion methods are presented and discussed. This paper can provide the theoretical support for the multi-sensor fusion for two-phase flow measurement.

  6. Free-stream temperature, density, and pressure measurements in an expansion tube flow

    NASA Technical Reports Server (NTRS)

    Haggard, K. V.

    1973-01-01

    An experimental study was conducted to determine test-flow conditions in the Langley pilot model expansion tube. Measurements of temperature, density, wall pressure, pitot pressure, and shock and interface velocities were compared with theoretical calculations based on various models of the flow cycle. The vibrational temperature and integrated density of the molecular oxygen component of the flow were measured by use of vacuum ultraviolet absorption techniques. These measurements indicate both the presence and possible degree of nonequilibrium in the flow. Data are compared with several simplified models of the flow cycle, and data trends are discussed.

  7. Neural network analysis of pulp flow speed in low coherence Doppler flowmetry measurement

    NASA Astrophysics Data System (ADS)

    Hannula, Manne; Alarousu, Erkki; Prykäri, Tuukka; Myllylä, Risto

    2007-03-01

    Low Coherence Doppler Flowmetry (LCDF) measurement produces a signal, which frequency domain characteristics are in connection to the speed of the flow. In this study a LCDF measurement data of pulp flow in a capillary was analyzed with a simple Artificial Neural Network (ANN) method to estimate the flow speed. The accuracy of the method proved to be good, validation of the method resulted in absolute error of 14 +/- 11 percentage units (mean+/-std) in flow speed estimation. The results of the study can be utilized in development of industrial pulp flow speed measurement instruments.

  8. Self-Contained Compressed-Flow Generation Device for Use in Making Differential Measurements

    NASA Technical Reports Server (NTRS)

    England, John Dwight (Inventor); Kelley, Anthony R. (Inventor); Cronise, Raymond J. (Inventor)

    2014-01-01

    A device used in making differential measurements of a flow includes a flow obstruction and a support arm. The flow obstruction's forward portion is a nose cone. The flow obstruction's aft portion is coupled to the nose cone. The support arm's first end is coupled to an exterior wall of a conduit, and its second end is coupled to the forward portion of the flow obstruction. The support arm positions the flow obstruction in the conduit such that a flow region is defined around its nose cone, and such that the support arm's first and second end are separated from one another with respect to a length dimension of the conduit. Measurement ports are provided in the support arm and flow obstruction. Manifolds extending through the flow obstruction and support arm couple the ports to points at the exterior wall of the conduit.

  9. Study on the feasibility of a precise measurement of the {tau} dependence of the cross sections for Drell-Yan experiments at moderate energies

    SciTech Connect

    Bianconi, A.

    2006-09-01

    Recently, a reconsideration of Drell-Yan cross sections at moderate energies and masses has suggested the possibility of relevant enhancements of the cross sections in some kinematical regions. If confirmed, these predictions could largely affect the planning of Drell-Yan experiments aimed at transverse spin measurements after 2010. More in general, the problem is present of a precision measurement of the {tau} dependence of Drell-Yan cross sections. Here we discuss the feasibility of such a measurement within short time at the COMPASS apparatus, and its relevance for the PANDA experiment.

  10. An ultrasonic flowmeter for measuring dynamic liquid flow

    NASA Technical Reports Server (NTRS)

    Carpini, T. D.; Monteith, J. H.

    1978-01-01

    A novel oscillating pipe system was developed to provide dynamic calibration wherein small sinusoidal signals with amplitudes of 0.5 to 10% of the steady-state flow were added to the steady-state flow by oscillating the flowmeter relative to the fixed pipes in the flow system. Excellent agreement was obtained between the dynamic velocities derived from an accelerometer mounted on the oscillating pipe system and those sensed by the flowmeter at frequencies of 7, 19, and 30 Hz. Also described were the signal processing techniques used to retrieve the small sinusoidal signals which were obscured by the fluid turbulence.

  11. The Importance of Measurement Errors for Deriving Accurate Reference Leaf Area Index Maps for Validation of Moderate-Resolution Satellite LAI Products

    NASA Technical Reports Server (NTRS)

    Huang, Dong; Yang, Wenze; Tan, Bin; Rautiainen, Miina; Zhang, Ping; Hu, Jiannan; Shabanov, Nikolay V.; Linder, Sune; Knyazikhin, Yuri; Myneni, Ranga B.

    2006-01-01

    The validation of moderate-resolution satellite leaf area index (LAI) products such as those operationally generated from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor data requires reference LAI maps developed from field LAI measurements and fine-resolution satellite data. Errors in field measurements and satellite data determine the accuracy of the reference LAI maps. This paper describes a method by which reference maps of known accuracy can be generated with knowledge of errors in fine-resolution satellite data. The method is demonstrated with data from an international field campaign in a boreal coniferous forest in northern Sweden, and Enhanced Thematic Mapper Plus images. The reference LAI map thus generated is used to assess modifications to the MODIS LAI/fPAR algorithm recently implemented to derive the next generation of the MODIS LAI/fPAR product for this important biome type.

  12. Measurement of Retinal Blood Flow Using Fluorescently Labeled Red Blood Cells1,2,3

    PubMed Central

    Kornfield, Tess E.

    2015-01-01

    Abstract Blood flow is a useful indicator of the metabolic state of the retina. However, accurate measurement of retinal blood flow is difficult to achieve in practice. Most existing optical techniques used for measuring blood flow require complex assumptions and calculations. We describe here a simple and direct method for calculating absolute blood flow in vessels of all sizes in the rat retina. The method relies on ultrafast confocal line scans to track the passage of fluorescently labeled red blood cells (fRBCs). The accuracy of the blood flow measurements was verified by (1) comparing blood flow calculated independently using either flux or velocity combined with diameter measurements, (2) measuring total retinal blood flow in arterioles and venules, (3) measuring blood flow at vessel branch points, and (4) measuring changes in blood flow in response to hyperoxic and hypercapnic challenge. Confocal line scans oriented parallel and diagonal to vessels were used to compute fRBC velocity and to examine velocity profiles across the width of vessels. We demonstrate that these methods provide accurate measures of absolute blood flow and velocity in retinal vessels of all sizes. PMID:26082942

  13. A method for measuring cooling air flow in base coolant passages of rotating turbine blades

    NASA Technical Reports Server (NTRS)

    Liebert, C. H.; Pollack, F. G.

    1975-01-01

    Method accurately determines actual coolant mass flow rate in cooling passages of rotating turbine blades. Total and static pressures are measured in blade base coolant passages. Mass flow rates are calculated from these measurements of pressure, measured temperature and known area.

  14. Development of a low flow meter for measuring gas production in bioreactors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate measurement of gas production from biological processes is important in many laboratory experiments. A gas flow rate measurement system, consisting of an embedded controller operating three gas meters, was developed to measure volumetric flows between 0 and 8 ml min-1 (1 atm, 273.15 K). The...

  15. Evolution of a natural debris flow: In situ measurements of flow dynamics, video imagery, and terrestrial laser scanning

    USGS Publications Warehouse

    McCoy, S.W.; Kean, J.W.; Coe, J.A.; Staley, D.M.; Wasklewicz, T.A.; Tucker, G.E.

    2010-01-01

    Many theoretical and laboratory studies have been undertaken to understand debris-flow processes and their associated hazards. However, complete and quantitative data sets from natural debris flows needed for confirmation of these results are limited. We used a novel combination of in situ measurements of debris-flow dynamics, video imagery, and pre- and postflow 2-cm-resolution digital terrain models to study a natural debris-flow event. Our field data constrain the initial and final reach morphology and key flow dynamics. The observed event consisted of multiple surges, each with clear variation of flow properties along the length of the surge. Steep, highly resistant, surge fronts of coarse-grained material without measurable pore-fluid pressure were pushed along by relatively fine-grained and water-rich tails that had a wide range of pore-fluid pressures (some two times greater than hydrostatic). Surges with larger nonequilibrium pore-fluid pressures had longer travel distances. A wide range of travel distances from different surges of similar size indicates that dynamic flow properties are of equal or greater importance than channel properties in determining where a particular surge will stop. Progressive vertical accretion of multiple surges generated the total thickness of mapped debris-flow deposits; nevertheless, deposits had massive, vertically unstratified sedimentological textures. ?? 2010 Geological Society of America.

  16. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... measurement accuracy, coefficient of variability measurement accuracy, and the flow rate cut-off function. The... flow measurements are made at intervals not to exceed 5 minutes. The flow rate cut-off test, conducted... definitions. (1) Sample flow rate means the quantitative volumetric flow rate of the air stream caused by...

  17. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... measurement accuracy, coefficient of variability measurement accuracy, and the flow rate cut-off function. The... flow measurements are made at intervals not to exceed 5 minutes. The flow rate cut-off test, conducted... definitions. (1) Sample flow rate means the quantitative volumetric flow rate of the air stream caused by...

  18. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... measurement accuracy, coefficient of variability measurement accuracy, and the flow rate cut-off function. The... flow measurements are made at intervals not to exceed 5 minutes. The flow rate cut-off test, conducted... definitions. (1) Sample flow rate means the quantitative volumetric flow rate of the air stream caused by...

  19. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... measurement accuracy, coefficient of variability measurement accuracy, and the flow rate cut-off function. The... flow measurements are made at intervals not to exceed 5 minutes. The flow rate cut-off test, conducted... definitions. (1) Sample flow rate means the quantitative volumetric flow rate of the air stream caused by...

  20. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... measurement accuracy, coefficient of variability measurement accuracy, and the flow rate cut-off function. The... flow measurements are made at intervals not to exceed 5 minutes. The flow rate cut-off test, conducted... definitions. (1) Sample flow rate means the quantitative volumetric flow rate of the air stream caused by...