Novel monorail infusion catheter for volumetric coronary blood flow measurement in humans: in vitro validation.

PubMed

van 't Veer, Marcel; Adjedj, Julien; Wijnbergen, Inge; Tóth, Gabor G; Rutten, Marcel C M; Barbato, Emanuele; van Nunen, Lokien X; Pijls, Nico H J; De Bruyne, Bernard

2016-08-20

The aim of this study is to validate a novel monorail infusion catheter for thermodilution-based quantitative coronary flow measurements. Based on the principles of thermodilution, volumetric coronary flow can be determined from the flow rate of a continuous saline infusion, the temperature of saline when it enters the coronary artery, and the temperature of the blood mixed with the saline in the distal part of the coronary artery. In an in vitro set-up of the systemic and coronary circulation at body temperature, coronary flow values were varied from 50-300 ml/min in steps of 50 ml/min. At each coronary flow value, thermodilution-based measurements were performed at infusion rates of 15, 20, and 30 ml/min. Temperatures and pressures were simultaneously measured with a pressure/temperature sensor-tipped guidewire. Agreement of the calculated flow and the measured flow as well as repeatability were assessed. A total of five catheters were tested, with a total of 180 measurements. A strong correlation (ρ=0.976, p<0.0001) and a difference of -6.5±15.5 ml/min were found between measured and calculated flow. The difference between two repeated measures was 0.2%±8.0%. This novel infusion catheter used in combination with a pressure/temperature sensor-tipped guidewire allows accurate and repeatable absolute coronary flow measurements. This opens a window to a better understanding of the coronary microcirculation.

A field technique for estimating aquifer parameters using flow log data

USGS Publications Warehouse

Paillet, Frederick L.

2000-01-01

A numerical model is used to predict flow along intervals between producing zones in open boreholes for comparison with measurements of borehole flow. The model gives flow under quasi-steady conditions as a function of the transmissivity and hydraulic head in an arbitrary number of zones communicating with each other along open boreholes. The theory shows that the amount of inflow to or outflow from the borehole under any one flow condition may not indicate relative zone transmissivity. A unique inversion for both hydraulic-head and transmissivity values is possible if flow is measured under two different conditions such as ambient and quasi-steady pumping, and if the difference in open-borehole water level between the two flow conditions is measured. The technique is shown to give useful estimates of water levels and transmissivities of two or more water-producing zones intersecting a single interval of open borehole under typical field conditions. Although the modeling technique involves some approximation, the principle limit on the accuracy of the method under field conditions is the measurement error in the flow log data. Flow measurements and pumping conditions are usually adjusted so that transmissivity estimates are most accurate for the most transmissive zones, and relative measurement error is proportionately larger for less transmissive zones. The most effective general application of the borehole-flow model results when the data are fit to models that systematically include more production zones of progressively smaller transmissivity values until model results show that all accuracy in the data set is exhausted.A numerical model is used to predict flow along intervals between producing zones in open boreholes for comparison with measurements of borehole flow. The model gives flow under quasi-steady conditions as a function of the transmissivity and hydraulic head in an arbitrary number of zones communicating with each other along open boreholes. The theory shows that the amount of inflow to or outflow from the borehole under any one flow condition may not indicate relative zone transmissivity. A unique inversion for both hydraulic-head and transmissivity values is possible if flow is measured under two different conditions such as ambient and quasi-steady pumping, and if the difference in open-borehole water level between the two flow conditions is measured. The technique is shown to give useful estimates of water levels and transmissivities of two or more water-producing zones intersecting a single interval of open borehole under typical field conditions. Although the modeling technique involves some approximation, the principle limit on the accuracy of the method under field conditions is the measurement error in the flow log data. Flow measurements and pumping conditions are usually adjusted so that transmissivity estimates are most accurate for the most transmissive zones, and relative measurement error is proportionately larger for less transmissive zones. The most effective general application of the borehole-flow model results when the data are fit to models that symmetrically include more production zones of progressively smaller transmissivity values until model results show that all accuracy in the data set is exhausted.

Method of measuring cross-flow vortices by use of an array of hot-film sensors

NASA Technical Reports Server (NTRS)

Agarwal, Aval K. (Inventor); Maddalon, Dal V. (Inventor); Mangalam, Siva M. (Inventor)

1993-01-01

The invention is a method for measuring the wavelength of cross-flow vortices of air flow having streamlines of flow traveling across a swept airfoil. The method comprises providing a plurality of hot-film sensors. Each hot-film sensor provides a signal which can be processed, and each hot-film sensor is spaced in a straight-line array such that the distance between successive hot-film sensors is less than the wavelength of the cross-flow vortices being measured. The method further comprises determining the direction of travel of the streamlines across the airfoil and positioning the straight-line array of hot film sensors perpendicular to the direction of travel of the streamlines, such that each sensor has a spanwise location. The method further comprises processing the signals provided by the sensors to provide root-mean-square values for each signal, plotting each root-mean-square value as a function of its spanwise location, and determining the wavelength of the cross-flow vortices by noting the distance between two maxima or two minima of root-mean-square values.

Lava effusion rate definition and measurement: a review

USGS Publications Warehouse

Calvari, Sonia; Dehn, Jonathan; Harris, A.

2007-01-01

Measurement of effusion rate is a primary objective for studies that model lava flow and magma system dynamics, as well as for monitoring efforts during on-going eruptions. However, its exact definition remains a source of confusion, and problems occur when comparing volume flux values that are averaged over different time periods or spatial scales, or measured using different approaches. Thus our aims are to: (1) define effusion rate terminology; and (2) assess the various measurement methods and their results. We first distinguish between instantaneous effusion rate, and time-averaged discharge rate. Eruption rate is next defined as the total volume of lava emplaced since the beginning of the eruption divided by the time since the eruption began. The ultimate extension of this is mean output rate, this being the final volume of erupted lava divided by total eruption duration. Whether these values are total values, i.e. the flux feeding all flow units across the entire flow field, or local, i.e. the flux feeding a single active unit within a flow field across which many units are active, also needs to be specified. No approach is without its problems, and all can have large error (up to ∼50%). However, good agreement between diverse approaches shows that reliable estimates can be made if each approach is applied carefully and takes into account the caveats we detail here. There are three important factors to consider and state when measuring, giving or using an effusion rate. First, the time-period over which the value was averaged; second, whether the measurement applies to the entire active flow field, or a single lava flow within that field; and third, the measurement technique and its accompanying assumptions.

Turbulence measurements in hypersonic shock-wave boundary-layer interaction flows

NASA Technical Reports Server (NTRS)

Mikulla, V.; Horstman, C. C.

1976-01-01

Turbulent intensity and Reynolds shear stress measurements are presented for two nonadiabatic hypersonic shock-wave boundary-layer interaction flows, one with and one without separation. These measurements were obtained using a new hot-wire probe specially designed for heated flows. Comparison of the separated and attached flows shows a significant increase above equilibrium values in the turbulent intensity and shear stress downstream of the interaction region for the attached case, while for the separated case, the turbulent fluxes remain close to equilibrium values. This effect results in substantial differences in turbulence lifetimes for the two flows. It is proposed that these differences are due to a coupling between the turbulent energy and separation bubble unsteadiness, a hypothesis supported by the statistical properties of the turbulent fluctuations.

Diversifying natural resources value measurements: The Trinity River study

USGS Publications Warehouse

Taylor, J.G.; Douglas, A.J.

1999-01-01

An interdisciplinary team set out to establish the economic and social values of the Trinity River in northern California. This information was intended to support the Secretary of the Interior's decision on allocation of Trinity River flows. This team set out to measure the values of Trinity River flows, fishery resources, and recreation amenities in several different ways. A survey was mailed to users of the Trinity River. This single instrument included economic measures (willingness-to-pay and costs incurred in visiting) and social-psychological measures (importance, satisfaction, and water allocation preferences). A closely related survey measured several of these same values among west coast regional households. The results of these surveys were compiled, and the measured economic and social values were compared. We found that integrating economic and social value information provides a greater depth of understanding of the resource's value. In addition, this integration provides a more in-depth understanding through the quantitative and qualitative results that emerge.

Secondary Flows and Boundary-Layer Accumulations in Turbine Nozzles

NASA Technical Reports Server (NTRS)

Rohlik, Harold E; Kofskey, Milton G; Allen, Hubert W; Herzig, Howard Z

1954-01-01

An investigation of secondary-flow loss patterns originating in three sets of turbine nozzle blade passages was conducted by means of flow-visualization studies and detailed flow measurements. For all cases, high loss values were measured in the fluid downstream of the corners formed by the suction surfaces of the blades and the shrouds, and these losses were accompanied by discharge-angle deviations from design values. Despite the size of the loss regions and angle gradients, over-all mass-average blade efficiencies were of the order of 0.99 and 0.98 and, therefore, are not a good index of blade performance.

CBF measured by Xe-CT: Approach to analysis and normal values

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yonas, H.; Darby, J.M.; Marks, E.C.

1991-09-01

Normal reference values and a practical approach to CBF analysis are needed for routine clinical analysis and interpretation of xenon-enhanced computed tomography (CT) CBF studies. The authors measured CBF in 67 normal individuals with the GE 9800 CT scanner adapted for CBF imaging with stable Xe. CBF values for vascular territories were systematically analyzed using the clustering of contiguous 2-cm circular regions of interest (ROIs) placed within the cortical mantle and basal ganglia. Mixed cortical flows averaged 51 {plus minus} 10ml.100g-1.min-1. High and low flow compartments, sampled by placing 5-mm circular ROIs in regions containing the highest and lowest flowmore » values in each hemisphere, averaged 84 {plus minus} 14 and 20 {plus minus} 5 ml.100 g-1.min-1, respectively. Mixed cortical flow values as well as values within the high flow compartment demonstrated significant decline with age; however, there were no significant age-related changes in the low flow compartment. The clustering of systematically placed cortical and subcortical ROIs has provided a normative data base for Xe-CT CBF and a flexible and uncomplicated method for the analysis of CBF maps generated by Xe-enhanced CT.« less

Effect of Doppler flow meter position on discharge measurement in surcharged manholes.

PubMed

Yang, Haoming; Zhu, David Z; Liu, Yanchen

2018-02-01

Determining the proper installation location of flow meters is important for accurate measurement of discharge in sewer systems. In this study, flow field and flow regimes in two types of manholes under surcharged flow were investigated using a commercial computational fluid dynamics (CFD) code. The error in measuring the flow discharge using a Doppler flow meter (based on the velocity in a Doppler beam) was then estimated. The values of the corrective coefficient were obtained for the Doppler flow meter at different locations under various conditions. Suggestions for selecting installation positions are provided.

Fundamental supply of skin blood flow in the Chinese Han population: Measurements by a full-field laser perfusion imager.

PubMed

Fei, W; Xu, S; Ma, J; Zhai, W; Cheng, S; Chang, Y; Wang, X; Gao, J; Tang, H; Yang, S; Zhang, X

2018-05-08

Skin blood flow is believed to link with many diseases, and shows a significant heterogeneity. There are several papers on basal cutaneous microcirculation perfusion in different races, while the data in Chinese is vacant. The aim was to establish the database of absolute fundamental supply of skin blood flow in the Chinese Han population. With a full-field laser perfusion imager (FLPI), the skin blood flow can be quantified. Cutaneous perfusion values were determined in 17 selected skin areas in 406 healthy participants aged between 20 and 80 years (mean 35.05 ± 11.33). Essential parameters such as weight, height were also measured and values of BMI were calculated. The perfusion values were reported in Arbitrary Perfusion Units (APU). The highest cutaneous perfusion value fell on eyelid (931.20 ± 242.59 in male and 967.83 ± 225.49 in female), and pretibial had the lowest value (89.09 ± 30.28 in male and 85.08 ± 33.59 in female). The values were higher in men than women on the bank of fingertips, nose, forehead, cheek, neck and earlobe (P < .05). Perfusion values on stretch and flexion side of forearm had negative correlation with age (P = .01 and P = 4.88 × 10 -3 , respectively) in male. Abdomen was negatively correlated with BMI in both gender (P = .02, respectively). Skin blood flow values vary with skin regions. There is a tendency to measure higher perfusion values in men than in women. And the values are irrelevant with age or BMI. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Use of instantaneous streamflow measurements to improve regression estimates of index flow for the summer month of lowest streamflow in Michigan

USGS Publications Warehouse

Holtschlag, David J.

2011-01-01

In Michigan, index flow Q50 is a streamflow characteristic defined as the minimum of median flows for July, August, and September. The state of Michigan uses index flow estimates to help regulate large (greater than 100,000 gallons per day) water withdrawals to prevent adverse effects on characteristic fish populations. At sites where long-term streamgages are located, index flows are computed directly from continuous streamflow records as GageQ50. In an earlier study, a multiple-regression equation was developed to estimate index flows IndxQ50 at ungaged sites. The index equation explains about 94 percent of the variability of index flows at 147 (index) streamgages by use of six explanatory variables describing soil type, aquifer transmissivity, land cover, and precipitation characteristics. This report extends the results of the previous study, by use of Monte Carlo simulations, to evaluate alternative flow estimators, DiscQ50, IntgQ50, SiteQ50, and AugmQ50. The Monte Carlo simulations treated each of the available index streamgages, in turn, as a miscellaneous site where streamflow conditions are described by one or more instantaneous measurements of flow. In the simulations, instantaneous flows were approximated by daily mean flows at the corresponding site. All estimators use information that can be obtained from instantaneous flow measurements and contemporaneous daily mean flow data from nearby long-term streamgages. The efficacy of these estimators was evaluated over a set of measurement intensities in which the number of simulated instantaneous flow measurements ranged from 1 to 100 at a site. The discrete measurement estimator DiscQ50 is based on a simple linear regression developed between information on daily mean flows at five or more streamgages near the miscellaneous site and their corresponding GageQ50 index flows. The regression relation then was used to compute a DiscQ50 estimate at the miscellaneous site by use of the simulated instantaneous flow measurement. This process was repeated to develop a set of DiscQ50 estimates for all simulated instantaneous measurements, a weighted DiscQ50 estimate was formed from this set. Results indicated that the expected value of this weighted estimate was more precise than the IndxQ50 estimate for all measurement intensities evaluated. The integrated index-flow estimator, IntgQ50, was formed by computing a weighted average of the index estimate IndxQ50 and the DiscQ50 estimate. Results indicated that the IntgQ50 estimator was more precise than the DiscQ50 estimator at low measurement intensities of one to two measurements. At greater measurement intensities, the precision of the IntgQ50 estimator converges to the DiscQ50 estimator. Neither the DiscQ50 nor the IntgQ50 estimators provided site-specific estimates. In particular, although expected values of DiscQ50 and IntgQ50 estimates converge with increasing measurement intensity, they do not necessarily converge to the site-specific value of Q50. The site estimator of flow, SiteQ50, was developed to facilitate this convergence at higher measurement intensities. This is accomplished by use of the median of simulated instantaneous flow values for each measurement intensity level. A weighted estimate of the median and information associated with the IntgQ50 estimate was used to form the SiteQ50 estimate. Initial simulations indicate that the SiteQ50 estimator generally has greater precision than the IntgQ50 estimator at measurement intensities greater than 3, however, additional analysis is needed to identify streamflow conditions under which instantaneous measurements will produce estimates that generally converge to the index flows. A preliminary augmented index regression equation was developed, which contains the index regression estimate and two additional variables associated with base-flow recession characteristics. When these recession variables were estimated as the medians of recession parameters compute

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.

Collisional Shift and Broadening of Iodine Spectral Lines in Air Near 543 nm

NASA Technical Reports Server (NTRS)

Fletcher, D. G.; McDaniel, J. C.

1995-01-01

The collisional processes that influence the absorption of monochromatic light by iodine in air have been investigated. Measurements were made in both a static cell and an underexpanded jet flow over the range of properties encountered in typical compressible-flow aerodynamic applications. Experimentally measured values of the collisional shift and broadening coefficients were 0.058 +/- 0.004 and 0.53 +/- 0.010 GHz K(exp 0.7)/torr, respectively. The measured shift value showed reasonable agreement with theoretical calculations based on Lindholm-Foley collisional theory for a simple dispersive potential. The measured collisional broadening showed less favorable agreement with the calculated value.

Studies of lava flows in the Tharsis region of Mars using SHARAD

NASA Astrophysics Data System (ADS)

Simon, Molly N.; Carter, Lynn M.; Campbell, Bruce A.; Phillips, Roger J.; Mattei, Stefania

2014-11-01

The Tharsis region of Mars is covered in volcanic flows that can stretch for tens to hundreds of kilometers. Radar measurements of the dielectric properties of these flows can provide information regarding their composition and density. SHARAD (shallow radar), a sounding radar on the Mars Reconnaissance Orbiter, detects basal interfaces beneath flows in some areas of Tharsis northwest and west of Ascraeus Mons, with additional detections south of Pavonis Mons. Comparisons with 12.6 cm ground-based radar images suggest that SHARAD detects basal interfaces primarily in dust or regolith-mantled regions. We use SHARAD data to estimate the real relative permittivity of the flows by comparing the measured time delay of returns from the subsurface with altimetry measurements of the flow heights relative to the surrounding plains. In cases where the subsurface interface is visible at different depths, spanning tens of meters, it is also possible to measure the loss tangent (tan δ) of the material. The permittivity values calculated range from 7.6 to 11.6, with an average of 9.6, while the mean loss tangent values range from 7.8 × 10-3 to 2.9 × 10-2 with an average of 1.0 × 10-2. These permittivity and loss tangent estimates for the flows northwest of Ascraeus Mons, west of Ascraeus Mons, and south of Pavonis Mons are consistent with the lab-measured values for dense, low-titanium basalt.

Viscous slip coefficients for binary gas mixtures measured from mass flow rates through a single microtube

NASA Astrophysics Data System (ADS)

Yamaguchi, H.; Takamori, K.; Perrier, P.; Graur, I.; Matsuda, Y.; Niimi, T.

2016-09-01

The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip boundary condition can be applied. The measured viscous slip coefficients of binary gas mixtures exhibit a concave function of the molar ratio of the mixture, showing a similar profile with numerical results. However, from the detailed comparison between the measured and numerical values with the complete and incomplete accommodation at a surface, it is inappropriate to estimate the viscous slip coefficient for the mixture numerically by employing separately measured tangential momentum accommodation coefficient for each component. The time variation of the molar ratio in the downstream chamber was measured by sampling the gas from the chamber using the quadrupole mass spectrometer. In our measurements, it is indicated that the volume flow rate of argon is larger than that of helium because of the difference in the tangential momentum accommodation coefficient.

Seepage investigation on selected reaches of Fish Creek, Teton County, Wyoming, 2004

USGS Publications Warehouse

Wheeler, Jerrod D.; Eddy-Miller, Cheryl A.

2005-01-01

A seepage investigation was conducted on Fish Creek, a tributary to the Snake River in Teton County in western Wyoming, near Wilson. Mainstem, return flow, tributary, spring, and diversion sites were selected and measured on six reaches along Fish Creek. Flow was measured under two flow regimes, high flow in August 2004 and base flow in November 2004. During August 17-19, 2004, 20 sites had quantifiable discharge with median values ranging from 0.93 to 384 ft3/s for the 14 mainstem sites on Fish Creek, and from 0.35 to 12.2 ft3/s for the 5 return, spring, and tributary sites (inflows). The discharge was 2.23 ft3/s for the single diversion site (outflow). Estimated gains or losses from ground water were calculated for all reaches using the median discharge values and the estimated measurement errors. Reach 1 had a calculated gain in discharge from ground water (23.8 ?3.3 ft3/s). Reaches 2-6 had no calculated gains in flow, greater than the estimated error, that could be attributed to ground water. A second set of measurements were made under base-flow conditions during November 3-4, 2004. Twelve of the 20 sites visited in August 2004 were flowing and were measured. All of the Reach 1 sites near Teton Village were dry. Median discharge values ranged from 10.3 to 70.0 ft3/s on the nine Fish Creek mainstem sites, and from 2.32 to 3.71 ft3/s on the three return, spring, and tributary sites (inflows). Reaches 2, 3 and 6 had a gain from ground water. Reaches 4 and 5 had no calculated gains in flow, greater than the estimated error, that could be attributed to ground water.

Studies on unsteady pressure fields in the region of separating and reattaching flows

NASA Astrophysics Data System (ADS)

Govinda Ram, H. S.; Arakeri, V. H.

1990-12-01

Experimental studies on the measurement of pressure fields in the region of separating and reattaching flows behind several two-dimensional fore-bodies and one axisymmetric body are reported. In particular, extensive measurements of mean pressure, surface pressure fluctuation, and pressure fluctuation within the flow were made for a series of two-dimensional fore-body shapes consisting of triangular nose with varying included angle. The measurements from different bodies are compared and one of the important findings is that the maximum values of rms pressure fluctuation levels in the shear layer approaching reattachment are almost equal to the maximum value of the surface fluctuation levels.

Surveillance of hemodialysis vascular access with ultrasound vector flow imaging

NASA Astrophysics Data System (ADS)

Brandt, Andreas H.; Olesen, Jacob B.; Hansen, Kristoffer L.; Rix, Marianne; Jensen, Jørgen A.; Nielsen, Michael B.

2015-03-01

The aim of this study was prospectively to monitor the volume flow in patients with arteriovenous fistula (AVF) with the angle independent ultrasound technique Vector Flow Imaging (VFI). Volume flow values were compared with Ultrasound dilution technique (UDT). Hemodialysis patients need a well-functioning vascular access with as few complications as possible and preferred vascular access is an AVF. Dysfunction due to stenosis is a common complication, and regular monitoring of volume flow is recommended to preserve AVF patency. UDT is considered the gold standard for volume flow surveillance, but VFI has proven to be more precise, when performing single repeated instantaneous measurements. Three patients with AVF were monitored with UDT and VFI monthly for five months. A commercial ultrasound scanner with a 9 MHz linear array transducer with integrated VFI was used to obtain data. UDT values were obtained with Transonic HD03 Flow-QC Hemodialysis Monitor. Three independent measurements at each scan session were obtained with UDT and VFI each month. Average deviation of volume flow between UDT and VFI was 25.7 % (Cl: 16.7% to 34.7%) (p= 0.73). The standard deviation for all patients, calculated from the mean variance of each individual scan sessions, was 199.8 ml/min for UDT and 47.6 ml/min for VFI (p = 0.002). VFI volume flow values were not significantly different from the corresponding estimates obtained using UDT, and VFI measurements were more precise than UDT. The study indicates that VFI can be used for surveillance of volume flow.

MR imaging of apparent 3He gas transport in narrow pipes and rodent airways

NASA Astrophysics Data System (ADS)

Minard, Kevin R.; Jacob, Richard E.; Laicher, Gernot; Einstein, Daniel R.; Kuprat, Andrew P.; Corley, Richard A.

2008-10-01

High sensitivity makes hyperpolarized 3He an attractive signal source for visualizing gas flow with magnetic resonance (MR) imaging. Its rapid Brownian motion, however, can blur observed flow lamina and alter measured diffusion rates when excited nuclei traverse shear-induced velocity gradients during data acquisition. Here, both effects are described analytically, and predicted values for measured transport during laminar flow through a straight, 3.2-mm diameter pipe are validated using two-dimensional (2D) constant-time images of different binary gas mixtures. Results show explicitly how measured transport in narrow conduits is characterized by apparent values that depend on underlying gas dynamics and imaging time. In ventilated rats, this is found to obscure acquired airflow images. Nevertheless, flow splitting at airway branches is still evident and use of 3D vector flow mapping is shown to reveal surprising detail that highlights the correlation between gas dynamics and lung structure.

Determination of local values of gas and liquid mass flux in highly loaded two-phase flow

NASA Technical Reports Server (NTRS)

Burick, R. J.; Scheuerman, C. H.; Falk, A. Y.

1974-01-01

A measurement system using a deceleration probe was designed for determining the local values of gas and liquid mass flux in various gas/liquid droplet sprayfields. The system was used to characterize two-phase flowfields generated by gas/liquid rocket-motor injectors. Measurements were made at static pressures up to 500 psia and injected mass flow ratios up to 20. The measurement system can also be used at higher pressures and in gas/solid flowfields.

Instabilities of mixed convection flows adjacent to inclined plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abu-Mulaweh, H.I.; Armaly, B.F.; Chen, T.S.

1987-11-01

The measurements by Sparrow and Husar and by Lloyd and Sparrow established that the onset of instability (transition from laminar to turbulent) in free convection boundary layer flow above an inclined heated plate is predominated by the wave mode of instability for inclination angles less than 14 deg, as measured from the vertical, and by the vortex mode of instability for angles greater than 17 deg. The transition Grashof number deceased as the angle of inclination increased. The predictions of Chen and Tzuoo for this flow provide trends that are similar to measured values, but the predicted critical Grashof numbersmore » deviate significantly (three orders of magnitude smaller) from measured values. The instability of mixed convection boundary layer flow adjacent to inclined heated plates have also been treated numerically by Chen and Mucoglu for wave instability and by Chen et al. for vortex instability. Comparisons with measurements of instability in mixed convection flow adjacent to inclined plates were not available in the literature. It is anticipated, however, that these predictions will underestimate the actual onset of instability, as in the free convection case. The lack of measurements in this flow domain for this geometry has motivated the present study. The onset of instability in mixed convection flow adjacent to an isothermally heated inclined plate was determined in this study through flow visualization. The buoyancy-assisting and buoyancy-opposing flow cases were examined for the flow both above and below the heated plate. The critical Grashof-Reynolds number relationships for the onset of instability in this flow domain are reported in this paper.« less

Systematic heat flow measurements across the Wagner Basin, northern Gulf of California

NASA Astrophysics Data System (ADS)

Neumann, Florian; Negrete-Aranda, Raquel; Harris, Robert N.; Contreras, Juan; Sclater, John G.; González-Fernández, Antonio

2017-12-01

A primary control on the geodynamics of rifting is the thermal regime. To better understand the geodynamics of rifting in the northern Gulf of California we systematically measured heat-flow across the Wagner Basin, a tectonically active basin that lies near the southern terminus of the Cerro Prieto fault. The heat flow profile is 40 km long, has a nominal measurement spacing of ∼1 km, and is collocated with a seismic reflection profile. Heat flow measurements were made with a 6.5-m violin-bow probe. Although heat flow data were collected in shallow water, where there are significant temporal variations in bottom water temperature, we use CTD data collected over many years to correct our measurements to yield accurate values of heat flow. After correction for bottom water temperature, the mean and standard deviation of heat flow across the western, central, and eastern parts of the basin are 220 ± 60, 99 ± 14, 889 ± 419 mW m-2, respectively. Corrections for sedimentation would increase measured heat flow across the central part of basin by 40 to 60%. We interpret the relatively high heat flow and large variability on the western and eastern flanks in terms of upward fluid flow at depth below the seafloor, whereas the lower and more consistent values across the central part of the basin are suggestive of conductive heat transfer. Moreover, heat flow across the central basin is consistent with gabbroic underplating at a depth of 15 km and suggests that continental rupture here has not gone to completion.

Towards metering tap water by Lorentz force velocimetry

NASA Astrophysics Data System (ADS)

Vasilyan, Suren; Ebert, Reschad; Weidner, Markus; Rivero, Michel; Halbedel, Bernd; Resagk, Christian; Fröhlich, Thomas

2015-11-01

In this paper, we present enhanced flow rate measurement by applying the contactless Lorentz Force Velocimetry (LFV) technique. Particularly, we show that the LFV is a feasible technique for metering the flow rate of salt water in a rectangular channel. The measurements of the Lorentz forces as a function of the flow rate are presented for different electrical conductivities of the salt water. The smallest value of conductivity is achieved at 0.06 S·m-1, which corresponds to the typical value of tap water. In comparison with previous results, the performance of LFV is improved by approximately 2 orders of magnitude by means of a high-precision differential force measurement setup. Furthermore, the sensitivity curve and the calibration factor of the flowmeter are provided based on extensive measurements for the flow velocities ranging from 0.2 to 2.5 m·s-1 and conductivities ranging from 0.06 to 10 S·m-1.

Interpretation of lunar heat flow data. [for estimating bulk uranium abundance

NASA Technical Reports Server (NTRS)

Conel, J. E.; Morton, J. B.

1975-01-01

Lunar heat flow observations at the Apollo 15 and 17 sites can be interpreted to imply bulk U concentrations for the moon of 5 to 8 times those of normal chondrites and 2 to 4 times terrestrial values inferred from the earth's heat flow and the assumption of thermal steady state between surface heat flow and heat production. A simple model of nearsurface structure that takes into account the large difference in (highly insulating) regolith thickness between mare and highland provinces is considered. This model predicts atypically high local values of heat flow near the margins of mare regions - possibly a factor of 10 or so higher than the global average. A test of the proposed model using multifrequency microwave techniques appears possible wherein heat flow traverse measurements are made across mare-highland contacts. The theoretical considerations discussed here urge caution in attributing global significance to point heat-flow measurements on the moon.

Arcjet Flow Properties Determined from Laser-Induced Fluorescence of Atomic Species

NASA Technical Reports Server (NTRS)

Fletcher, Douglas G.

1997-01-01

Flow property measurements that were recently acquired in the Ames Research Center Aerodynamic Heating Facility (AHF) arc jet using two-photon Laser-Induced Fluorescence (LIF) of atomic nitrogen and oxygen are reported. The measured properties, which include velocity, translational temperature, and species concentration, cover a wide range of facility operation for the 30 cm nozzle. During the tests, the arc jet pressure and input stream composition were maintained at fixed values and the arc current was varied to vary the flow enthalpy. As part of this ongoing effort, a measurement of the two-photon absorption coefficient for the 3p4D<-2p4S transition of atomic nitrogen was performed, and the measured value is used to convert the relative concentration measurements to absolute values. A flow reactor is used to provide a known temperature line shape profile to deconvolve the laser line width contribution to the translational temperature measurements. Results from the current experiments are compared with previous results obtained using NO-Beta line profiles at room temperature and the problem of multimode laser oscillation and its impact on the two-photon excitation line shape are discussed. One figure is attached, and this figure shows relative N atom concentration measurements as a function of the arc power. Other measurements have already been acquired and analyzed. This poster represents an application of laser-spectroscopic measurements in an important test facility. The arc jet flow facilities are heavily used in thermal protection material development and evaluation. All hypersonic flight and planetary atmospheric entry vehicles will use materials tested in these arc jet facilities.

Model calibration and issues related to validation, sensitivity analysis, post-audit, uncertainty evaluation and assessment of prediction data needs

USGS Publications Warehouse

Tiedeman, Claire; Hill, Mary C.

2007-01-01

When simulating natural and engineered groundwater flow and transport systems, one objective is to produce a model that accurately represents important aspects of the true system. However, using direct measurements of system characteristics, such as hydraulic conductivity, to construct a model often produces simulated values that poorly match observations of the system state, such as hydraulic heads, flows and concentrations (for example, Barth et al., 2001). This occurs because of inaccuracies in the direct measurements and because the measurements commonly characterize system properties at different scales from that of the model aspect to which they are applied. In these circumstances, the conservation of mass equations represented by flow and transport models can be used to test the applicability of the direct measurements, such as by comparing model simulated values to the system state observations. This comparison leads to calibrating the model, by adjusting the model construction and the system properties as represented by model parameter values, so that the model produces simulated values that reasonably match the observations.

Reentry heating analysis of space shuttle with comparison of flight data

NASA Technical Reports Server (NTRS)

Gong, L.; Quinn, R. D.; Ko, W. L.

1982-01-01

Surface heating rates and surface temperatures for a space shuttle reentry profile were calculated for two wing cross sections and one fuselage cross section. Heating rates and temperatures at 12 locations on the wing and 6 locations on the fuselage are presented. The heating on the lower wing was most severe, with peak temperatures reaching values of 1240 C for turbulent flow and 900 C for laminar flow. For the fuselage, the most severe heating occured on the lower glove surface where peak temperatures of 910 C and 700 C were calculated for turbulent flow and laminar flow, respectively. Aluminum structural temperatures were calculated using a finite difference thermal analyzer computer program, and the predicted temperatures are compared to measured flight data. Skin temperatures measured on the lower surface of the wing and bay 1 of the upper surface of the wing agreed best with temperatures calculated assuming laminar flow. The measured temperatures at bays two and four on the upper surface of the wing were in quite good agreement with the temperatures calculated assuming separated flow. The measured temperatures on the lower forward spar cap of bay four were in good agreement with values predicted assuming laminar flow.

A study of disequilibrium between 220Rn and 216Po for 220Rn measurements using a flow-through Lucas scintillation cell.

PubMed

Sathyabama, N; Datta, D; Gaware, J J; Mayya, Y S; Tripathi, R M

2014-01-01

Lucas-type scintillation cells (LSCs) are commonly used for rapid measurements of (220)Rn concentrations in flow-through mode in field and for calibration experiments in laboratories. However, in those measurements, equilibrium between (220)Rn and (216)Po is generally assumed and two alpha particles are considered to be emitted per (220)Rn decay due to very short half-life of (216)Po. In this paper, a small, yet significant disequilibrium existing between (220)Rn and (216)Po has been examined and shown that less than two alpha particles are actually emitted per (220)Rn decay in the cell when flow is maintained. A theoretical formula has been derived for the first time for a correction factor (CF) to be applied to this measured concentration to account for the disequilibrium. The existence of this disequilibrium has been verified experimentally and is found to increase with the increase in the ratio of flow rate to cell volume. The reason for the disequilibrium is attributed to the flushing out of (216)Po formed in the cell before its decay due to the flow. Uncertainties in measured concentrations have been estimated and the estimated CF values have been found to be significant for the flow rates considered above 5 dm(3) min(-1) for a cell of volume 0.125 dm(3). The calculated values of the CF are about 1.055 to 1.178 in the flow rate range of 4 to 15 dm(3) min(-1) for the cell of volume 0.125 dm(3), while the corresponding experimental values are 1.023 to 1.264. This is a systematic error introduced in (220)Rn measurements using a flow-through LSC, which can be removed either by correct formulation or by proper design of a measurement set-up.

Is there a necessity for individual blood water corrections when conductivity-based access blood flow measurements are made?

PubMed

Huang, Shih-Han S; Heidenheim, Paul A; Gallo, Kerri; Jayakumar, Saumya; Lindsay, Robert M

2011-01-01

Access blood water flow rate (Qaw) can be measured during hemodialysis using an online effective ionic dialysance (EID) methodology. Fresenius employ this methodology in their 2008K dialysis machine. The machine computer converts Qaw to an access blood flow rate (Fresenius Qa) using a generic blood water constant (BWC). We wished to validate this BWC. 18 patients had Fresenius Qa measurements using the EID and these were compared with a 'gold standard' ultrasound dilution methodology (Transonic Qa). Qa values were also obtained by removing the BWC from Fresenius Qa values to obtain the Qaw and recorrecting it with individualized patient factors using hematocrit and total protein values (HctTp Qa). The measurements were repeated after 1 h. There were no significant differences between Fresenius and Transonic, nor between HctTp and Transonic Qa values (p > 0.17). There were strong correlations between both sets of values (r > 0.856; p < 0.001). There was a significant correlation between the pairs of Transonic Qa values (r = 0.823; p < 0.007), but not for Fresenius Qa pairs (r = 0.573; p > 0.07). It was surmised that the BWC was not valid post-dialysis. The generic BWC is comparable to individualized blood water correction factors when Qa measures are made early in dialysis and prior to ultrafiltration treatment. Copyright © 2011 S. Karger AG, Basel.

The renal blood flow reserve in healthy humans and patients with atherosclerotic renovascular disease measured by positron emission tomography using [15O]H2O.

PubMed

Päivärinta, Johanna; Koivuviita, Niina; Oikonen, Vesa; Iida, Hidehiro; Liukko, Kaisa; Manner, Ilkka; Löyttyniemi, Eliisa; Nuutila, Pirjo; Metsärinne, Kaj

2018-06-11

Microvascular function plays an important role in ARVD (atherosclerotic renovascular disease). RFR (renal flow reserve), the capacity of renal vasculature to dilate, is known to reflect renal microvascular function. In this pilot study, we assessed PET (positron emission tomography)-based RFR values of healthy persons and renal artery stenosis patients. Seventeen patients with ARVD and eight healthy subjects were included in the study. Intravenous enalapril 1 mg was used as a vasodilatant, and the maximum response (blood pressure and RFR) to it was measured at 40 min. Renal perfusion was measured by means of oxygen-15-labeled water PET. RFR was calculated as a difference of stress flow and basal flow and was expressed as percent [(stress blood flow - basal blood flow)/basal blood flow] × 100%. RFR of the healthy was 22%. RFR of the stenosed kidneys of bilateral stenosis patients (27%) was higher than that of the stenosed kidneys of unilateral stenosis patients (15%). RFR of the contralateral kidneys of unilateral stenosis patients was 21%. There was no difference of statistical significance between RFR values of ARVD subgroups or between ARVD subgroups and the healthy. In the stenosed kidneys of unilateral ARVD patients, stenosis grade of the renal artery correlated negatively with basal (p = 0.04) and stress flow (p = 0.02). Dispersion of RFR values was high. This study is the first to report [ 15 O]H 2 O PET-based RFR values of healthy subjects and ARVD patients in humans. The difference between RFR values of ARVD patients and the healthy did not reach statistical significance perhaps because of high dispersion of RFR values. [ 15 O]H 2 O PET is a valuable non-invasive and quantitative method to evaluate renal blood flow though high dispersion makes imaging challenging. Larger studies are needed to get more information about [ 15 O]H 2 O PET method in evaluation of renal blood flow.

Portal hypertension in patients with cirrhosis: indirect assessment of hepatic venous pressure gradient by measuring azygos flow with 2D-cine phase-contrast magnetic resonance imaging.

PubMed

Gouya, Hervé; Grabar, Sophie; Vignaux, Olivier; Saade, Anastasia; Pol, Stanislas; Legmann, Paul; Sogni, Philippe

2016-07-01

To measure azygos, portal and aortic flow by two-dimensional cine phase-contrast magnetic resonance imaging (2D-cine PC MRI), and to compare the MRI values to hepatic venous pressure gradient (HVPG) measurements, in patients with cirrhosis. Sixty-nine patients with cirrhosis were prospectively included. All patients underwent HVPG measurements, upper gastrointestinal endoscopy and 2D-cine PC MRI measurements of azygos, portal and aortic blood flow. Univariate and multivariate regression analyses were used to evaluate the correlation between the blood flow and HVPG. The performance of 2D-cine PC MRI to diagnose severe portal hypertension (HVPG ≥ 16 mmHg) was determined by receiver operating characteristic curve (ROC) analysis, and area under the curves (AUC) were compared. Azygos and aortic flow values were associated with HVPG in univariate linear regression model. Azygos flow (p < 10(-3)), aortic flow (p = 0.001), age (p = 0.001) and presence of varices (p < 10(-3)) were independently associated with HVPG. Azygos flow (AUC = 0.96 (95 % CI [0.91-1.00]) had significantly higher AUC than aortic (AUC = 0.64 (95 % CI [0.51-0.77]) or portal blood flow (AUC = 0.40 (95 % CI [0.25-0.54]). 2D-cine PC MRI is a promising technique to evaluate significant portal hypertension in patients with cirrhosis. • Noninvasive HVPG assessment can be performed with MRI azygos flow. • Azygos MRI flow is an easy-to-measure marker to detect significant portal hypertension. • MRI flow is more specific that varice grade to detect portal hypertension.

Development of In-Fiber Reflective Bragg Gratings as Shear Stress Monitors in Aerodynamic Facilities

NASA Technical Reports Server (NTRS)

Parmar, Devendra S.; Sprinkle, Danny R.; Singh, Jag J.

1998-01-01

Bragg gratings centered at nominal wavelengths of 1290 nm and 1300 run were inscribed in a 9/125 microns germano-silicate optical fiber, using continuous wave frequency doubled Ar+ laser radiation at 244 nm. Such gratings have been used extensively as temperature and strain monitors in smart structures. They have, however, never been used for measuring aerodynamic shear stresses. As a test of their sensitivity as shear stress monitors, a Bragg fiber attached to a metal plate was subjected to laminar flows in a glass pipe. An easily measurable large flow-induced wavelength shift (Delta Lambda(sub B)) was observed in the Bragg reflected wavelength. Thereafter, the grating was calibrated by making one time, simultaneous measurements of Delta Lambda(sub B) and the coefficient of skin friction (C(sub f)) with a skin friction balance, as a function of flow rates in a subsonic wind tunnel. Onset of fan-induced transition in the tunnel flow provided a unique flow rate for correlating Delta Lambda(sub B) and (C(sub f) values needed for computing effective modulus of rigidity (N(sub eff)) of the fiber attached to the metal plate. This value Of N(sub eff) is expected to remain constant throughout the elastic stress range expected during the Bragg grating aerodynamic tests. It has been used for calculating the value of Cf at various tunnel speeds, on the basis of measured values of Bragg wavelength shifts at those speeds.

New leak assembly based on fluidic nanochannels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Aiqing; Zhao, Yongheng; Wang, Xudi, E-mail: wxudi@hfut.edu.cn

2016-09-15

Fluidic nanochannels with a characteristic dimension of ∼280 nm were fabricated and designed as a leak assembly, where the nanochannels were formed on silicon wafers and enclosed with Pyrex{sup ®} glass. The geometric dimensions were characterized by scanning electron microscopy, and the gas flow conductance of He and other heavy gases (N{sub 2}, O{sub 2}, and Ar) was measured, and its uncertainty estimated, by the difference method. The results indicated that the measured flow conductance values were 45% less than the calculated flow conductance values. For helium, molecular flow was shown to occur at pressures ranging from vacuum to atmospheric pressure.more » As a consequence of the well-defined geometry, the prediction of flow conductance could be achieved for various gas species.« less

Quantitative framework for preferential flow initiation and partitioning

USGS Publications Warehouse

Nimmo, John R.

2016-01-01

A model for preferential flow in macropores is based on the short-range spatial distribution of soil matrix infiltrability. It uses elementary areas at two different scales. One is the traditional representative elementary area (REA), which includes a sufficient heterogeneity to typify larger areas, as for measuring field-scale infiltrability. The other, called an elementary matrix area (EMA), is smaller, but large enough to represent the local infiltrability of soil matrix material, between macropores. When water is applied to the land surface, each EMA absorbs water up to the rate of its matrix infiltrability. Excess water flows into a macropore, becoming preferential flow. The land surface then can be represented by a mesoscale (EMA-scale) distribution of matrix infiltrabilities. Total preferential flow at a given depth is the sum of contributions from all EMAs. Applying the model, one case study with multi-year field measurements of both preferential and diffuse fluxes at a specific depth was used to obtain parameter values by inverse calculation. The results quantify the preferential–diffuse partition of flow from individual storms that differed in rainfall amount, intensity, antecedent soil water, and other factors. Another case study provided measured values of matrix infiltrability to estimate parameter values for comparison and illustrative predictions. These examples give a self-consistent picture from the combination of parameter values, directions of sensitivities, and magnitudes of differences caused by different variables. One major practical use of this model is to calculate the dependence of preferential flow on climate-related factors, such as varying soil wetness and rainfall intensity.

Near-field entrainment in black smoker plumes

NASA Astrophysics Data System (ADS)

Smith, J. E.; Germanovich, L. N.; Lowell, R. P.

2013-12-01

In this work, we study the entrainment rate of the ambient fluid into a plume in the extreme conditions of hydrothermal venting at ocean floor depths that would be difficult to reproduce in the laboratory. Specifically, we investigate the flow regime in the lower parts of three black smoker plumes in the Main Endeavour Field on the Juan de Fuca Ridge discharging at temperatures of 249°C, 333°C, and 336°C and a pressure of 21 MPa. Such flow conditions are typical for ocean floor hydrothermal venting but would be difficult to reproduce in the laboratory. The centerline temperature was measured at several heights in the plume above the orifice. Using a previously developed turbine flow meter, we also measured the mean flow velocity at the orifice. Measurements were conducted during dives 4452 and 4518 on the submersible Alvin. Using these measurements, we obtained a range of 0.064 - 0.068 for values of the entrainment coefficient α, which is assumed constant near the orifice. This is half the value of α ≈ 0.12 - 0.13 that would be expected for plume flow regimes based on the existing laboratory results and field measurements in lower temperature and pressure conditions. In fact, α = 0.064 - 0.068 is even smaller than the value of α ≈ 0.075 characteristic of jet flow regimes and appears to be the lowest reported in the literature. Assuming that the mean value α = 0.066 is typical for hydrothermal venting at ocean floor depths, we then characterized the flow regimes of 63 black smoker plumes located on the Endeavor Segment of the Juan de Fuca Ridge. Work with the obtained data is ongoing, but current results indicate that approximately half of these black smokers are lazy in the sense that their plumes exhibit momentum deficits compared to the pure plume flow that develops as the plume rises. The remaining half produces forced plumes that show the momentum excess compared to the pure plumes. The lower value of the entrainment coefficient has important implications for measurements of mass and heat output at mid-oceanic ridges. For example, determining heat output based on the maximum height of plume rise has become a common method of measuring heat flux produced by hydrothermal circulation at mid-oceanic ridges. The fundamental theory for the rise and spreading of turbulent buoyant plumes suggests that the heat output in this method is proportional to α2 and is, therefore, sensitive to the value of α. The considerably different entrainment rates in lazy and forced black smoker plumes may be important for understanding larvae transport mechanism in the life cycle of macrofauna near hydrothermal vents.

Wide-range measurement of thermal effusivity using molybdenum thin film with low thermal conductivity for thermal microscopes

NASA Astrophysics Data System (ADS)

Miyake, Shugo; Matsui, Genzou; Ohta, Hiromichi; Hatori, Kimihito; Taguchi, Kohei; Yamamoto, Suguru

2017-07-01

Thermal microscopes are a useful technology to investigate the spatial distribution of the thermal transport properties of various materials. However, for high thermal effusivity materials, the estimated values of thermophysical parameters based on the conventional 1D heat flow model are known to be higher than the values of materials in the literature. Here, we present a new procedure to solve the problem which calculates the theoretical temperature response with the 3D heat flow and measures reference materials which involve known values of thermal effusivity and heat capacity. In general, a complicated numerical iterative method and many thermophysical parameters are required for the calculation in the 3D heat flow model. Here, we devised a simple procedure by using a molybdenum (Mo) thin film with low thermal conductivity on the sample surface, enabling us to measure over a wide thermal effusivity range for various materials.

16 CFR 460.5 - R-value tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... INSULATION 460.5 R-value tests. R-value measures resistance to heat flow. R-values given in labels, fact...) All types of insulation except aluminum foil must be tested with ASTM C 177-04, “Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded...

16 CFR 460.5 - R-value tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... INSULATION 460.5 R-value tests. R-value measures resistance to heat flow. R-values given in labels, fact...) All types of insulation except aluminum foil must be tested with ASTM C 177-04, “Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded...

16 CFR 460.5 - R-value tests.

Code of Federal Regulations, 2012 CFR

2012-01-01

... INSULATION 460.5 R-value tests. R-value measures resistance to heat flow. R-values given in labels, fact...) All types of insulation except aluminum foil must be tested with ASTM C 177-04, “Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded...

16 CFR 460.5 - R-value tests.

Code of Federal Regulations, 2013 CFR

2013-01-01

... INSULATION 460.5 R-value tests. R-value measures resistance to heat flow. R-values given in labels, fact...) All types of insulation except aluminum foil must be tested with ASTM C 177-04, “Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded...

16 CFR 460.5 - R-value tests.

Code of Federal Regulations, 2014 CFR

2014-01-01

... INSULATION 460.5 R-value tests. R-value measures resistance to heat flow. R-values given in labels, fact...) All types of insulation except aluminum foil must be tested with ASTM C 177-04, “Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded...

Calculation and measurement of a neutral air flow velocity impacting a high voltage capacitor with asymmetrical electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malík, M., E-mail: michal.malik@tul.cz; Primas, J.; Kopecký, V.

2014-01-15

This paper deals with the effects surrounding phenomenon of a mechanical force generated on a high voltage asymmetrical capacitor (the so called Biefeld-Brown effect). A method to measure this force is described and a formula to calculate its value is also given. Based on this the authors derive a formula characterising the neutral air flow velocity impacting an asymmetrical capacitor connected to high voltage. This air flow under normal circumstances lessens the generated force. In the following part this velocity is measured using Particle Image Velocimetry measuring technique and the results of the theoretically calculated velocity and the experimentally measuredmore » value are compared. The authors found a good agreement between the results of both approaches.« less

Three-dimensional flow measurements in a vaneless radial turbine scroll

NASA Technical Reports Server (NTRS)

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

1982-01-01

The flow behavior in a vaneless radial turbine scroll was examined experimentally. The data was obtained using the slant sensor technique of hot film anemometry. This method used the unsymmetric heat transfer characteristics of a constant temperature hot film sensor to detect the flow direction and magnitude. This was achieved by obtaining a velocity vector measurement at three sensor positions with respect to the flow. The true magnitude and direction of the velocity vector was then found using these values and a Newton-Raphson numerical technique. The through flow and secondary flow velocity components are measured at various points in three scroll sections.

Activation energy measurements of cheese

USDA-ARS?s Scientific Manuscript database

Temperature sweeps of cheeses using small amplitude oscillatory shear tests produced values for activation energy of flow (Ea) between 30 and 44 deg C. Soft goat cheese and Queso Fresco, which are high-moisture cheeses and do not flow when heated, exhibited Ea values between 30 and 60 kJ/mol. The ...

Quantitative values of blood flow through the human forearm, hand, and finger as functions of temperature

NASA Technical Reports Server (NTRS)

Montgomery, L. D.

1974-01-01

A literature search was made to obtain values of human forearm, hand and finger blood flow as functions of environmental temperature. The sources used include both government and laboratory reports and the research presented in the open literature. An attempt was made to review many of the more quantitative noninvasive determinations and to collate the results in such a way as to yield blood flow values for each body segment as continuous functions of temperature. A brief review of the various ways used to measure blood flow is included along with an abstract of each work from which data was taken.

Base-flow data in the Arnold Air Force Base area, Tennessee, June and October 2002

USGS Publications Warehouse

Robinson, John A.; Haugh, Connor J.

2004-01-01

Arnold Air Force Base (AAFB) occupies about 40,000 acres in Coffee and Franklin Counties, Tennessee. The primary mission of AAFB is to support the development of aerospace systems. This mission is accomplished through test facilities at Arnold Engineering Development Center (AEDC), which occupies about 4,000 acres in the center of AAFB. Base-flow data including discharge, temperature, and specific conductance were collected for basins in and near AAFB during high base-flow and low base-flow conditions. Data representing high base-flow conditions from 109 sites were collected on June 3 through 5, 2002, when discharge measurements at sites with flow ranged from 0.005 to 46.4 ft3/s. Data representing low base-flow conditions from 109 sites were collected on October 22 and 23, 2002, when discharge measurements at sites with flow ranged from 0.02 to 44.6 ft3/s. Discharge from the basin was greater during high base-flow conditions than during low base-flow conditions. In general, major tributaries on the north side and southeastern side of the study area (Duck River and Bradley Creek, respectively) had the highest flows during the study. Discharge data were used to categorize stream reaches and sub-basins. Stream reaches were categorized as gaining, losing, wet, dry, or unobserved for each base-flow measurement period. Gaining stream reaches were more common during the high base-flow period than during the low base-flow period. Dry stream reaches were more common during the low base-flow period than during the high base-flow period. Losing reaches were more predominant in Bradley Creek and Crumpton Creek. Values of flow per square mile for the study area of 0.55 and 0.37 (ft3/s)/mi2 were calculated using discharge data collected on June 3 through 5, 2002, and October 22 and 23, 2002, respectively. Sub-basin areas with surplus or deficient flow were defined within the basin. Drainage areas for each stream measurement site were delineated and measured from topographic maps. Change in flow per square mile for each sub-basin was calculated using data from each base-flow measurement period. The calculated values were used to define the areas of surplus or deficient flow for high and low base-flow conditions. Many areas of deficient flow were present throughout the study area under high and low base-flow conditions. Most areas of deficient flow were in the headwater basins. Fewer areas of surplus flow were present under low base-flow conditions than during the high base-flow conditions. The flow per square mile for each major tributary basin in the study area also was calculated. The values of flow per square mile for the Dry Creek, Spring Creek, and Wiley Creek basins were greatest under both high and low base-flow conditions.

40 CFR 1065.230 - Raw exhaust flow meter.

Code of Federal Regulations, 2010 CFR

2010-07-01

... flow meter. (a) Application. You may use measured raw exhaust flow, as follows: (1) Use the actual... the following cases, you may use a raw exhaust flow meter signal that does not give the actual value... consumed. (b) Component requirements. We recommend that you use a raw-exhaust flow meter that meets the...

A laser interferometer for measuring skin friction in three-dimensional flows

NASA Technical Reports Server (NTRS)

Monson, D. J.

1983-01-01

A new, nonintrusive method is described for measuring skin friction in three-dimensional flows with unknown direction. The method uses a laser interferometer to measure the changing slope of a thin oil film applied to a surface experiencing shear stress. The details of the method are described, and skin friction measurements taken in a swirling three-dimensional boundary-layer flow are presented. Comparisons between analytical results and experimental values from the laser interferometer method and from a bidirectional surface-fence gauge are made.

Off-design flow measurements in a centrifugal compressor vaneless diffuser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pinarbasi, A.; Johnson, M.W.

1995-10-01

Detailed measurements have been taken of the three-dimensional velocity field within the vaneless diffuser of a backswept low speed centrifugal compressor using hot-wire anemometry. A 16% below and an 11% above design flow rate were used in the present study. Results at both flow rates show how the blade wake mixes out more rapidly than the passage wake. Strong secondary flows inherited from the impeller at the higher flow rate delay the mixing out of the circumferential velocity variations, but at both flow rates these circumferential variations are negligible at the last measurement station. The measured tangential/radial flow angle ismore » used to recommend optimum values for the vaneless space and vane angle for design of a vaned diffuser.« less

Intra- and Inter-rater Agreement of Superior Vena Cava Flow and Right Ventricular Outflow Measurements in Late Preterm and Term Neonates.

PubMed

Mahoney, Liam; Fernandez-Alvarez, Jose R; Rojas-Anaya, Hector; Aiton, Neil; Wertheim, David; Seddon, Paul; Rabe, Heike

2018-02-24

To explore the intra- and inter-rater agreement of superior vena cava (SVC) flow and right ventricular (RV) outflow in healthy and unwell late preterm neonates (33-37 weeks' gestational age), term neonates (≥37 weeks' gestational age), and neonates receiving total-body cooling. The intra- and inter-rater agreement (n = 25 and 41 neonates, respectively) rates for SVC flow and RV outflow were determined by echocardiography in healthy and unwell late preterm and term neonates with the use of Bland-Altman plots, the repeatability coefficient, the repeatability index, and intraclass correlation coefficients. The intra-rater repeatability index values were 41% for SVC flow and 31% for RV outflow, with intraclass correlation coefficients indicating good agreement for both measures. The inter-rater repeatability index values for SVC flow and RV outflow were 63% and 51%, respectively, with intraclass correlation coefficients indicating moderate agreement for both measures. If SVC flow or RV outflow is used in the hemodynamic treatment of neonates, sequential measurements should ideally be performed by the same clinician to reduce potential variability. © 2018 by the American Institute of Ultrasound in Medicine.

Pulsatility of Lenticulostriate Arteries Assessed by 7 Tesla Flow MRI-Measurement, Reproducibility, and Applicability to Aging Effect.

PubMed

Schnerr, Roald S; Jansen, Jacobus F A; Uludag, Kamil; Hofman, Paul A M; Wildberger, Joachim E; van Oostenbrugge, Robert J; Backes, Walter H

2017-01-01

Characterization of flow properties in cerebral arteries with 1.5 and 3 Tesla MRI is usually limited to large cerebral arteries and difficult to evaluate in the small perforating arteries due to insufficient spatial resolution. In this study, we assessed the feasibility to measure blood flow waveforms in the small lenticulostriate arteries with 7 Tesla velocity-sensitive MRI. The middle cerebral artery was included as reference. Imaging was performed in five young and five old healthy volunteers. Flow was calculated by integrating time-varying velocity values over the vascular cross-section. MRI acquisitions were performed twice in each subject to determine reproducibility. From the flow waveforms, the pulsatility index and damping factor were deduced. Reproducibility values, in terms of the intraclass correlation coefficients, were found to be good to excellent. Measured pulsatility index of the lenticulostriate arteries significantly increased and damping factor significantly decreased with age. In conclusion, we demonstrate that blood flow through the lenticostriate arteries can be precisely measured using 7 Tesla MRI and reveal effects of arterial stiffness due to aging. These findings hold promise to provide relevant insights into the pathologies involving perforating cerebral arteries.

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. © 2013 ISA Published by ISA All rights reserved.

Patient state index and cerebral blood flow changes during shoulder arthroscopy in beach chair position.

PubMed

Buget, Mehmet Ilke; Atalar, Ata Can; Edipoglu, Ipek Saadet; Sungur, Zerrin; Sivrikoz, Nukhet; Karadeniz, Meltem; Saka, Esra; Kucukay, Suleyman; Senturk, Mert N

2016-01-01

The aim of the study were to demonstrate the possible hemodynamic changes and cerebral blood flow alterations in patients who were positioned from supine to beach chair position; and to detect if the position change causes any cortical activity alteration as measured by the 4-channeled electroencephalography monitor. 35 patients were included. Before the induction, mean arterial pressure and patient state index values were recorded (T0). After the intubation, doppler-ultrasonography of the patients' internal carotid and vertebral arteries were evaluated to acquire cerebral blood flow values from the formula. In supine position, mean arterial pressure, patient state index and cerebral blood flow values were recorded (T1) and the patient was positioned to beach chair position. After 5min all measurements were repeated (T2). Measurements of patient state index and mean arterial pressure were repeated after 20 (T3), and 40 (T4)min. There was a significant decrease between T0 and T1 in heart rate (80.5±11.6 vs. 75.9±14.4beats/min), MAP (105.8±21.9 vs. 78.9±18.4mmHg) and PSI (88.5±8.3 vs. 30.3±9.7) (all p<0.05). Mean arterial pressure decreased significantly after position change, and remained decreased, compared to T1. The overall analysis of patient state index values (T1-T4) showed no significant change; however, comparing only T1 and T2 resulted in a statically significant decrease in patient state index. There was a significant decrease in cerebral blood flow after beach chair position. Beach chair position was associated with a decrease in cerebral blood flow and patient state index values. Patient state index was affected by the gravitational change of the cerebral blood flow; however, both factors were not directly correlated to each other. Moreover, the decrease in patient state index value was transient and returned to normal values within 20min. Copyright © 2015 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

[Patient state index and cerebral blood flow changes during shoulder arthroscopy in beach chair position].

PubMed

Buget, Mehmet Ilke; Atalar, Ata Can; Edipoglu, Ipek Saadet; Sungur, Zerrin; Sivrikoz, Nukhet; Karadeniz, Meltem; Saka, Esra; Kucukay, Suleyman; Senturk, Mert N

2016-01-01

The aim of the study were to demonstrate the possible hemodynamic changes and cerebral blood flow alterations in patients who were positioned from supine to beach chair position; and to detect if the position change causes any cortical activity alteration as measured by the 4-channeled electroencephalography monitor. 35 patients were included. Before the induction, mean arterial pressure and patient state index values were recorded (T0). After the intubation, doppler-ultrasonography of the patients' internal carotid and vertebral arteries were evaluated to acquire cerebral blood flow values from the formula. In supine position, mean arterial pressure, patient state index and cerebral blood flow values were recorded (T1) and the patient was positioned to beach chair position. After 5min all measurements were repeated (T2). Measurements of patient state index and mean arterial pressure were repeated after 20 (T3), and 40 (T4)min. There was a significant decrease between T0 and T1 in heart rate (80.5±11.6 vs. 75.9±14.4beats/min), MAP (105.8±21.9 vs. 78.9±18.4mmHg) and PSI (88.5±8.3 vs. 30.3±9.7) (all p<0.05). Mean arterial pressure decreased significantly after position change, and remained decreased, compared to T1. The overall analysis of patient state index values (T1-T4) showed no significant change; however, comparing only T1 and T2 resulted in a statically significant decrease in patient state index. There was a significant decrease in cerebral blood flow after beach chair position. Beach chair position was associated with a decrease in cerebral blood flow and patient state index values. Patient state index was affected by the gravitational change of the cerebral blood flow; however, both factors were not directly correlated to each other. Moreover, the decrease in patient state index value was transient and returned to normal values within 20min. Copyright © 2015 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

Further development and testing of the metabolic gas analyzer

NASA Technical Reports Server (NTRS)

1973-01-01

Continued development of a metabolic monitor utilizing a mass spectrometer and digital computer to perform measurements and data reduction, is reported. The device prints-out breath-by-breath values for 02 consumption, C02 production, minute volume and tidal volume. The flow is measured by introduction of a tracer gas to the expired gas stream. Design modifications to reduce pressure drop in the flow splitter to one inch of water at 600 liters/min flow and to extend the range of linear flow measurement to 1000 liters/min are discussed.

ESTIMATION OF SHEAR STRESS WORKING ON SUBMERGED HOLLOW FIBRE MEMBRANE BY CFD METHOD IN MBRs

NASA Astrophysics Data System (ADS)

Zaw, Hlwan Moe; Li, Tairi; Nagaoka, Hiroshi

This study was conducted to evaluate shear stress working on submerged hollow fibre membrane by CFD (Computation Fluid Dynamics) method in MBRs. Shear stress on hollow fibre membrane caused by aeration was measured directly using a two-direction load sensor. The measurement of water-phase flow velocity was done also by using laser doppler velocimeter. It was confirmed that the shear stress was possible to be evaluated from the water-phase flow velocityby the result of comparison of time average shear stress actually measured with one hollow fibre membrane and the one calculated by the water-phase flow velocity. In the estimation of the water-phase flow velocity using the CFD method, time average water-phase flow velocity estimated by consideration of the fluid resistance of the membrane module nearly coincided with the measured values, and it was shown that it was possible to be estimated also within the membrane module. Moreover, the measured shear stress and drag force well coincided with the values calculated from the estimated water-phase flow velocity outside of membrane module and in the center of membrane module, and it was suggested that the shear stress on the hollow fibre membrane could be estimated by the CFD method in MBRs.

Accurate viscosity measurements of flowing aqueous glucose solutions with suspended scatterers using a dynamic light scattering approach with optical coherence tomography.

PubMed

Weatherbee, Andrew; Popov, Ivan; Vitkin, Alex

2017-08-01

The viscosity of turbid colloidal glucose solutions has been accurately determined from spectral domain optical coherence tomography (OCT) M-mode measurements and our recently developed OCT dynamic light scattering model. Results for various glucose concentrations, flow speeds, and flow angles are reported. The relative "combined standard uncertainty" uc(η) on the viscosity measurements was ±1% for the no-flow case and ±5% for the flow cases, a significant improvement in measurement robustness over previously published reports. The available literature data for the viscosity of pure water and our measurements differ by 1% (stagnant case) and 1.5% (flow cases), demonstrating good accuracy; similar agreement is seen across the measured glucose concentration range when compared to interpolated literature values. The developed technique may contribute toward eventual noninvasive glucose measurements in medicine. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Thermo-Osmotic Flow in Thin Films.

PubMed

Bregulla, Andreas P; Würger, Alois; Günther, Katrin; Mertig, Michael; Cichos, Frank

2016-05-06

We report on the first microscale observation of the velocity field imposed by a nonuniform heat content along the solid-liquid boundary. We determine both radial and vertical velocity components of this thermo-osmotic flow field by tracking single tracer nanoparticles. The measured flow profiles are compared to an approximate analytical theory and to numerical calculations. From the measured slip velocity we deduce the thermo-osmotic coefficient for both bare glass and Pluronic F-127 covered surfaces. The value for Pluronic F-127 agrees well with Soret data for polyethylene glycol, whereas that for glass differs from literature values and indicates the complex boundary layer thermodynamics of glass-water interfaces.

Evaluation of (/sup 18/F)-4-fluoroantipyrine as a new blood flow tracer for multiradionuclide autoradiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sako, K.; Diksic, M.; Kato, A.

This article reports the evaluation of (/sup 18/F)-4-fluoroantipyrine (FAP) as a quantitative blood flow tracer by comparing blood flow measured with (/sup 18/F)FAP to that determined simultaneously with (/sup 14/C)-4-iodoantipyrine (IAP), a standard blood flow tracer, by means of double-tracer autoradiography. The single-pass extraction value (m), which indicates diffusibility of a tracer, was determined according to the procedure described by Crone. The diffusibility of FAP was essentially the same as that of IAP. The brain-blood partition coefficient for FAP was found to be similar to that for IAP, 0.89 +/- 0.01. Values of local cerebral blood flow obtained with FAPmore » agree with those determined with IAP. From these results, we concluded that FAP is indeed as good a blood flow tracer as IAP. Since /sup 18/F is a positron-emitting radionuclide, it might be a useful tracer for blood flow measurement by positron emission tomography.« less

Myocardial blood flow quantification by Rb-82 cardiac PET/CT: A detailed reproducibility study between two semi-automatic analysis programs.

PubMed

Dunet, Vincent; Klein, Ran; Allenbach, Gilles; Renaud, Jennifer; deKemp, Robert A; Prior, John O

2016-06-01

Several analysis software packages for myocardial blood flow (MBF) quantification from cardiac PET studies exist, but they have not been compared using concordance analysis, which can characterize precision and bias separately. Reproducible measurements are needed for quantification to fully develop its clinical potential. Fifty-one patients underwent dynamic Rb-82 PET at rest and during adenosine stress. Data were processed with PMOD and FlowQuant (Lortie model). MBF and myocardial flow reserve (MFR) polar maps were quantified and analyzed using a 17-segment model. Comparisons used Pearson's correlation ρ (measuring precision), Bland and Altman limit-of-agreement and Lin's concordance correlation ρc = ρ·C b (C b measuring systematic bias). Lin's concordance and Pearson's correlation values were very similar, suggesting no systematic bias between software packages with an excellent precision ρ for MBF (ρ = 0.97, ρc = 0.96, C b = 0.99) and good precision for MFR (ρ = 0.83, ρc = 0.76, C b = 0.92). On a per-segment basis, no mean bias was observed on Bland-Altman plots, although PMOD provided slightly higher values than FlowQuant at higher MBF and MFR values (P < .0001). Concordance between software packages was excellent for MBF and MFR, despite higher values by PMOD at higher MBF values. Both software packages can be used interchangeably for quantification in daily practice of Rb-82 cardiac PET.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Randall, N.J.; Beard, R.W.; Sutherland, I.A.

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 havemore » value in the investigation of blood flow patterns in various clinical situations such as the pelvic pain syndrome and early pregnancy.« less

Water Conservation Measures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ian Metzger, Jesse Dean

2010-12-31

This software requires inputs of simple water fixture inventory information and calculates the water/energy and cost benefits of various retrofit opportunities. This tool includes water conservation measures for: Low-flow Toilets, Low-flow Urinals, Low-flow Faucets, and Low-flow Showheads. This tool calculates water savings, energy savings, demand reduction, cost savings, and building life cycle costs including: simple payback, discounted payback, net-present value, and savings to investment ratio. In addition this tool also displays the environmental benefits of a project.

Modeling and Simulation of the Gonghe geothermal field (Qinghai, China) Constrained by Geophysical

NASA Astrophysics Data System (ADS)

Zeng, Z.; Wang, K.; Zhao, X.; Huai, N.; He, R.

2017-12-01

The Gonghe geothermal field in Qinghai is important because of its variety of geothermal resource types. Now, the Gonghe geothermal field has been a demonstration area of geothermal development and utilization in China. It has been the topic of numerous geophysical investigations conducted to determine the depth to and the nature of the heat source, and to image the channel of heat flow. This work focuses on the causes of geothermal fields used numerical simulation method constrained by geophysical data. At first, by analyzing and inverting an magnetotelluric (MT) measurements profile across this area we obtain the deep resistivity distribution. Using the gravity anomaly inversion constrained by the resistivity profile, the density of the basins and the underlying rocks can be calculated. Combined with the measured parameters of rock thermal conductivity, the 2D geothermal conceptual model of Gonghe area is constructed. Then, the unstructured finite element method is used to simulate the heat conduction equation and the geothermal field. Results of this model were calibrated with temperature data for the observation well. A good match was achieved between the measured values and the model's predicted values. At last, geothermal gradient and heat flow distribution of this model are calculated(fig.1.). According to the results of geophysical exploration, there is a low resistance and low density region (d5) below the geothermal field. We recognize that this anomaly is generated by tectonic motion, and this tectonic movement creates a mantle-derived heat upstream channel. So that the anomalous basement heat flow values are higher than in other regions. The model's predicted values simulated using that boundary condition has a good match with the measured values. The simulated heat flow values show that the mantle-derived heat flow migrates through the boundary of the low-resistance low-density anomaly area to the Gonghe geothermal field, with only a small fraction moving to other regions. Therefore, the mantle-derived heat flow across the tectonic channel to the cohesive continuous supply heat for Gonghe geothermal field, is the main the main causes of abundant geothermal resources.

The influence of changes in blood flow on the accuracy of pulse oximetry in humans.

PubMed

Vegfors, M; Lindberg, L G; Lennmarken, C

1992-05-01

Oxygen saturation (SpO2) was measured with a pulse oximeter in ten healthy, young men breathing air. A pulse oximeter probe was attached to the second toe and a laser Doppler probe to the first toe of the same foot for measurement of changes in peripheral blood flow. The pulse oximeter and laser Doppler readings were simultaneously compared when the foot was positioned 40 cm (position 1) above heart level, elevated 10 cm (position 2) above heart level and horizontally at heart level (position 3). Using this experimental human model, we achieved various blood flows. The AC and DC optical signals used for determination of oxygen saturation were recorded from the pulse oximeter and analysed. There was a significant increase (P less than 0.05) between position 1 and 3 in blood flow as measured by the laser Doppler flow meter. The corresponding pulse oximeter readings of haemoglobin saturation also increased significantly (P less than 0.05) comparing these two leg positions. Analysing the AC- and DC optical signals, the AC value of infrared light increased considerably, while the AC value of the red light decreased slightly. The DC values of red and infrared light did not change significantly. In summary, when blood flow was decreased, the ratio of red to infrared transmitted light was changed, resulting in a low SpO2 reading.

Effective flow resistivity of highway pavements.

PubMed

Rochat, Judith L; Read, David R

2013-12-01

In the case of highway traffic noise, propagating sound is influenced by the ground over which it travels, whether it is the pavement itself or the ground between the highway and nearby communities. Properly accounting for ground type in modeling can increase accuracy in noise impact determinations and noise abatement design. Pavement-specific effective flow resistivity values are being investigated for inclusion in the Federal Highway Administration Traffic Noise Model, which uses these values in the sound propagation algorithms and currently applies a single effective flow resistivity value to all pavement. Pavement-specific effective flow resistivity values were obtained by applying a modified version of the American National Standards Institute S1.18 standard. The data analysis process was tailored to allow for increased sensitivity and extraction of effective flow resistivity values for a broad range of pavements (sound absorptive to reflective). For porous pavements (sound absorptive), it was determined that examination of the measured data can reveal influence from an underlying structure. Use of such techniques can aid in the design of quieter pavements.

Forming of film surface of very viscous liquid flowing with gas in pipes

NASA Astrophysics Data System (ADS)

Czernek, Krystian; Witczak, Stanisław

2017-10-01

The study presents the possible use of optoelectronic system for the measurement of the values, which are specific for hydrodynamics of two-phase gas liquid flow in vertical pipes, where a very-high-viscosity liquid forms a falling film in a pipe. The experimental method was provided, and the findings were presented and analysed for selected values, which characterize the two-phase flow. Attempt was also made to evaluate the effects of flow parameters and properties of the liquid on the gas-liquid interface value, which is decisive for the conditions of heat exchange and mass transfer in falling film equipment. The nature and form of created waves at various velocities were also described.

Streamflow gain/loss in the Republican River basin, Nebraska, March 1989

USGS Publications Warehouse

Johnson, Michaela R.; Stanton, Jennifer S.; Cornwall, James F.; Landon, Matthew K.

2002-01-01

This arc and point data set contains streamflow measurement sites and reaches indicating streamflow gain or loss under base-flow conditions along the Republican River and tributaries in Nebraska during March 21 to 22, 1989 (Boohar and others, 1990). These measurements were made to obtain data on ground-water/surface-water interaction. Flow was visually observed to be zero, was measured, or was estimated at 136 sites. The measurements were made on the main stem of the Republican River and all flowing tributaries that enter the Republican River above Swanson Reservoir and parts of the Frenchman, Red Willow, and Medicine Creek drainages in the Nebraska part of the Republican River Basin. Tributaries were followed upstream until the first road crossing where zero flow was encountered. For selected streams, points of zero flow upstream of the first zero flow site were also checked. Streamflow gain or loss for each stream reach was calculated by subtracting the streamflow values measured at the upstream end of the reach and values for contributing tributaries from the downstream value. The data obtained reflected base-flow conditions suitable for estimating streamflow gains and losses for stream reaches between sites. This digital data set was created by manually plotting locations of streamflow measurements. These points were used to designate stream-reach segments to calculate gain/loss per river mile. Reach segments were created by manually splitting the lines from a 1:250,000 hydrography data set (Soenksen and others, 1999) at every location where the streams were measured. Each stream-reach segment between streamflow-measurement sites was assigned a unique reach number. All other lines in the hydrography data set without reach numbers were omitted. This data set was created to archive the calculated streamflow gains and losses of selected streams in part of the Republican River Basin, Nebraska in March 1989, and make the data available for use with geographic information systems (GIS). If measurement sites are used separately from reaches, the maximum scale of 1:100,000 should not be exceeded. When used in conjunction with the reach segments, the maximum scale should not exceed 1:250,000.

Flow over bedforms in a large sand-bed river: A field investigation

USGS Publications Warehouse

Holmes, Robert R.; Garcia, Marcelo H.

2008-01-01

An experimental field study of flows over bedforms was conducted on the Missouri River near St. Charles, Missouri. Detailed velocity data were collected under two different flow conditions along bedforms in this sand-bed river. The large river-scale data reflect flow characteristics similar to those of laboratory-scale flows, with flow separation occurring downstream of the bedform crest and flow reattachment on the stoss side of the next downstream bedform. Wave-like responses of the flow to the bedforms were detected, with the velocity decreasing throughout the flow depth over bedform troughs, and the velocity increasing over bedform crests. Local and spatially averaged velocity distributions were logarithmic for both datasets. The reach-wise spatially averaged vertical-velocity profile from the standard velocity-defect model was evaluated. The vertically averaged mean flow velocities for the velocity-defect model were within 5% of the measured values and estimated spatially averaged point velocities were within 10% for the upper 90% of the flow depth. The velocity-defect model, neglecting the wake function, was evaluated and found to estimate thevertically averaged mean velocity within 1% of the measured values.  

A double-gaussian, percentile-based method for estimating maximum blood flow velocity.

PubMed

Marzban, Caren; Illian, Paul R; Morison, David; Mourad, Pierre D

2013-11-01

Transcranial Doppler sonography allows for the estimation of blood flow velocity, whose maximum value, especially at systole, is often of clinical interest. Given that observed values of flow velocity are subject to noise, a useful notion of "maximum" requires a criterion for separating the signal from the noise. All commonly used criteria produce a point estimate (ie, a single value) of maximum flow velocity at any time and therefore convey no information on the distribution or uncertainty of flow velocity. This limitation has clinical consequences especially for patients in vasospasm, whose largest flow velocities can be difficult to measure. Therefore, a method for estimating flow velocity and its uncertainty is desirable. A gaussian mixture model is used to separate the noise from the signal distribution. The time series of a given percentile of the latter, then, provides a flow velocity envelope. This means of estimating the flow velocity envelope naturally allows for displaying several percentiles (e.g., 95th and 99th), thereby conveying uncertainty in the highest flow velocity. Such envelopes were computed for 59 patients and were shown to provide reasonable and useful estimates of the largest flow velocities compared to a standard algorithm. Moreover, we found that the commonly used envelope was generally consistent with the 90th percentile of the signal distribution derived via the gaussian mixture model. Separating the observed distribution of flow velocity into a noise component and a signal component, using a double-gaussian mixture model, allows for the percentiles of the latter to provide meaningful measures of the largest flow velocities and their uncertainty.

Measurement of blood flow through the retinal circulation of the cat during normoxia and hypoxemia using fluorescent microspheres.

PubMed

Ahmed, J; Pulfer, M K; Linsenmeier, R A

2001-09-01

The most successful method for measuring absolute blood flow rate through the retinal circulation has been the use of radioactive microspheres. The purpose of this study was to develop a microsphere method that did not have the drawbacks associated with radioactivity and to use this method to make measurements of retinal blood flow in the cat. Blood flow measurements were made by injecting 15-microm-diameter polystyrene microspheres into the left ventricle of anesthetized, artificially ventilated cats. These microspheres were labeled with one of three fluorescent dyes. Retinal blood flow measurements were made by determining the number of spheres that were embedded in the retina and comparing them to the number found in a reference sample. Spheres in the retina were counted by making retinal whole mounts and taking retinal images with a CCD camera mounted on an epifluorescence microscope equipped with filter sets appropriate for imaging the dyes used to label the spheres. Blood flow measurements made under normal conditions showed a mean retinal blood flow of 19.8 +/- 12.4 ml/min 100 g tissue (mean +/- SD; n = 15 cats). Since the retinal circulation perfuses only the inner half of the retina, the effective flow rate in that region is about twice this value. RBF increased during hypoxemia (P(a)O2 < 42 mm Hg) to 336% of the normoxic value on average. Analysis of sphere deposition patterns showed that the central retina had a higher blood flow than the peripheral retina, although this difference was significant only during hypoxemia. We conclude that even with a relatively small number of spheres deposited in the retina, the technique can reveal important properties of the retinal circulation. Copyright 2001 Academic Press.

Ultrasonic Blood Flow Measurement in Haemodialysis

PubMed Central

Sampson, D.; Papadimitriou, M.; Kulatilake, A. E.

1970-01-01

A 5-megacycle Doppler flow meter, calibrated in-vitro, was found to give a linear response to blood flow in the ranges commonly encountered in haemodialysis. With this, blood flow through artificial kidneys could be measured simply and with a clinically acceptable error. The method is safe, as blood lines do not have to be punctured or disconnected and hence there is no risk of introducing infection. Besides its value as a research tool the flow meter is useful in evaluating new artificial kidneys. Suitably modified it could form the basis of an arterial flow alarm system. PMID:5416812

Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling

NASA Technical Reports Server (NTRS)

Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.

2011-01-01

Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.

Effects of a Rotating Aerodynamic Probe on the Flow Field of a Compressor Rotor

NASA Technical Reports Server (NTRS)

Lepicovsky, Jan

2008-01-01

An investigation of distortions of the rotor exit flow field caused by an aerodynamic probe mounted in the rotor is described in this paper. A rotor total pressure Kiel probe, mounted on the rotor hub and extending up to the mid-span radius of a rotor blade channel, generates a wake that forms additional flow blockage. Three types of high-response aerodynamic probes were used to investigate the distorted flow field behind the rotor. These probes were: a split-fiber thermo-anemometric probe to measure velocity and flow direction, a total pressure probe, and a disk probe for in-flow static pressure measurement. The signals acquired from these high-response probes were reduced using an ensemble averaging method based on a once per rotor revolution signal. The rotor ensemble averages were combined to construct contour plots for each rotor channel of the rotor tested. In order to quantify the rotor probe effects, the contour plots for each individual rotor blade passage were averaged into a single value. The distribution of these average values along the rotor circumference is a measure of changes in the rotor exit flow field due to the presence of a probe in the rotor. These distributions were generated for axial flow velocity and for static pressure.

Heat-transfer measurements of the 1983 Kilauea lava flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

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.

Retinal blood flow detection in diabetic patients by Doppler Fourier domain optical coherence tomography◊

PubMed Central

Wang, Yimin; Fawzi, Amani; Tan, Ou; Gil-Flamer, John; Huang, David

2010-01-01

We present human retinal blood flow investigation for diabetic patients using Doppler Fourier domain optical coherence tomography (FD-OCT). The scanning pattern consisted of two concentric circles around the optic nerve head. The blood flow in one patient with diabetes and no retinpathy and another patient with treated proliferative diabetic retinopathy were measured. The patient without retinopathy showed a total blood flow value at the lower level of the normal range. The flow distribution between superior and inferior retina was balanced. The patient with diabetic retinopathy had a flow value lower than the normal people. Our study shows that Doppler FD-OCT can be used to evaluate the total retinal blood flow in patients with retinal diseases. PMID:19259246

Systems and methods for thermal imaging technique for measuring mixing of fluids

DOEpatents

Booten, Charles; Tomerlin, Jeff; Winkler, Jon

2016-06-14

Systems and methods for thermal imaging for measuring mixing of fluids are provided. In one embodiment, a method for measuring mixing of gaseous fluids using thermal imaging comprises: positioning a thermal test medium parallel to a direction gaseous fluid flow from an outlet vent of a momentum source, wherein when the source is operating, the fluid flows across a surface of the medium; obtaining an ambient temperature value from a baseline thermal image of the surface; obtaining at least one operational thermal image of the surface when the fluid is flowing from the outlet vent across the surface, wherein the fluid has a temperature different than the ambient temperature; and calculating at least one temperature-difference fraction associated with at least a first position on the surface based on a difference between temperature measurements obtained from the at least one operational thermal image and the ambient temperature value.

Heat transfer and fluid mechanics measurements in transitional boundary layer flows

NASA Technical Reports Server (NTRS)

Wang, T.; Simon, T. W.; Buddhavarapu, J.

1985-01-01

Experimental results are presented to document hydrodynamic and thermal development of flat-plate boundary layers undergoing natural transition. Local heat transfer coefficients, skin friction coefficients and profiles of velocity, temperature and Reynolds normal and shear stresses are presented. A case with no transition and transitional cases with 0.68% and 2.0% free-stream disturbance intensities were investigated. The locations of transition are consistent with earlier data. A late-laminar state with significant levels of turbulence is documented. In late-transitional and early-turbulent flows, turbulent Prandtl number and conduction layer thickness values exceed, and the Reynolds analogy factor is less than, values previously measured in fully turbulent flows.

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

NASA Technical Reports Server (NTRS)

Kenny, R Jeremy; Hulka, James R.

2008-01-01

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

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.

[Positron emission tomographic evaluations on hemodynamics and glucose metabolism of brain tumors and perifocal edematous tissues].

PubMed

Mizukawa, N; Hino, A; Imahori, Y; Tenjin, H; Yano, I; Yoshino, E; Hirakawa, K; Yamashita, M; Oki, F; Nakahashi, H

1989-03-01

Blood flow and glucose metabolism of the tumors and perifocal edematous tissues were evaluated using positron emission tomography (PET). Thirty-one brain tumor cases were investigated 12 non glial tumors (9 meningiomas and 3 metastatic tumors) and 19 gliomas (these were classified in 5 astrocytomas, 7 anaplastic astrocytomas and 7 glioblastomas, according to the malignancy). The diagnosis were confirmed pathologically in 30 cases. Cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2), oxygen extraction fraction (OEF) and cerebral blood volume (CBV) were measured by O-15 labeled gases inhalation methods. Cerebral metabolic rate for glucose (CMFglu) were measured by F-18 Deoxyglucose intravenous injection method and calculated by Hutchins's formula. The rate constant (ks) and lumped constant (LC) used in this study were the same as those published by Phelps et al. in 1979. The blood flow and glucose metabolic rates of tumors were measured by the same methods. The results were as follows: 1) Meningiomas showed very high blood flow and blood volume with a wide range. The OEF and metabolic rate for glucose (MRglu) values were very low. 2) Metastatic tumors showed the low values of blood flow, metabolic rate for oxygen (MRO2) and OEF. 3) The blood flow and MRglu values on gliomas were varied with no significant differences between the three subgroups. On the other hands, as the malignancy of the glioma increased, a statistically significant increase in blood volume and a decrease in OEF were noted. 4) The OEF values from the various types of tumors studied were significantly lower than those obtained from the normal tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of automatic measurement of contrast flow intensity: an innovative tool in contrast-enhanced ultrasound imaging of atherosclerotic carotid plaque neovascularization. A pilot study.

PubMed

Lisowska, A; Knapp, M; Tycinska, A; Sawicki, R; Kralisz, P; Lisowski, P; Sobkowicz, B; Musial, W I

2014-02-01

Contrast-enhanced ultrasound imaging of the carotid arteries (CECU) permits direct, real-time visualization of neovascularization in atherosclerotic plaques and is a confirmed predictor of unstable atheromatous lesions. The aim of the study was the assessment of a new, automatically measured index of intensity in quantitative estimation of the contrast flow through the carotid plaque (till now assessed only visually). Forty-four patients (mean age 70.4±11.4) with ultrasound diagnosed significant stenosis of internal carotid artery (ICA), after cerebrovascular or cardiovascular events, qualified for carotid artery stenting (CAS) were examined. The carotid ultrasound examinations with contrast agent Sonovue were performed. Visually in 22 patients (50%) contrast flow through the atherosclerotic plaques was found. In 17 patients (38.6%) massive, calcified atherosclerotic plaques were present. Patients with preserved contrast flow through the plaque more frequently had a history of cerebral stroke (P=0.04). Massive calcifications of atherosclerotic plaques correlated with a previous MI (P=0.03) and the degree of advancement of coronary artery disease (P=0.04), but not with a previous cerebral stroke. Contrast flow through the atherosclerotic plaque positively correlated with values of the index of intensity (r=0.69, P<0.00001). In patients with preserved contrast flow the mean value of the index of intensity was 22.24±3.55 dB as compared with 12.37±7.67 dB - a value present in patients without preserved contrast flow. No significant relation for the degree of calcifications and the value of the index of intensity was found. The assessment of the index of intensity is a novel, simple and automatic method to estimate the degree of contrast flow through the carotid plaque. The values of the index of intensity correlate with the contrast flow through the atherosclerotic plaque, but not with its calcification.

An alternative method to estimate zero flow temperature differences for Granier's thermal dissipation technique.

PubMed

Regalado, Carlos M; Ritter, Axel

2007-08-01

Calibration of the Granier thermal dissipation technique for measuring stem sap flow in trees requires determination of the temperature difference (DeltaT) between a heated and an unheated probe when sap flow is zero (DeltaT(max)). Classically, DeltaT(max) has been estimated from the maximum predawn DeltaT, assuming that sap flow is negligible at nighttime. However, because sap flow may continue during the night, the maximum predawn DeltaT value may underestimate the true DeltaT(max). No alternative method has yet been proposed to estimate DeltaT(max) when sap flow is non-zero at night. A sensitivity analysis is presented showing that errors in DeltaT(max) may amplify through sap flux density computations in Granier's approach, such that small amounts of undetected nighttime sap flow may lead to large diurnal sap flux density errors, hence the need for a correct estimate of DeltaT(max). By rearranging Granier's original formula, an optimization method to compute DeltaT(max) from simultaneous measurements of diurnal DeltaT and micrometeorological variables, without assuming that sap flow is negligible at night, is presented. Some illustrative examples are shown for sap flow measurements carried out on individuals of Erica arborea L., which has needle-like leaves, and Myrica faya Ait., a broadleaf species. We show that, although DeltaT(max) values obtained by the proposed method may be similar in some instances to the DeltaT(max) predicted at night, in general the values differ. The procedure presented has the potential of being applied not only to Granier's method, but to other heat-based sap flow systems that require a zero flow calibration, such as the Cermák et al. (1973) heat balance method and the T-max heat pulse system of Green et al. (2003).

Determination of cohesive and normal stresses and simulation of fluidization using kinetic theory

NASA Astrophysics Data System (ADS)

Bezbaruah, R.

1991-08-01

The general objective of this study is focused on the solid stresses involved in gas-solid flow. These stresses are generally included in the momentum conservation equations, essentially for stability and to prevent particles from collapsing to unreasonably low values of gas volume fraction. The first half of this work undertakes the measurement of the stresses in various powders by direct means, while the second part uses a newly developed kinetic theory constitutive equation for stress to predict the flow and also the solid's viscosity in a CFB. The cohesive or tensile stress found to exist in some classes of powders is measured using a Cohetester, based on which a cohesive force model is derived, which is sensitive to the characteristic properties of the powder material. The normal stress is measured using a Consolidometer, and the powder solid's modulus is obtained as a function of the volume fraction. The solid's modulus is seen to vary with particle size and particle type, with the smaller size particles being more compressible. The simulation of flow in the CFB using Gidaspow's (1991) extension of Ding's (1990) kinetic theory model to dilute phase flow, predicts realistic values of solids' viscosity that are comparable to viscosities obtained experimentally by Miller (1991). However, to obtain a match between the two, the value of the restitution coefficient has to be close to unity. The flow behavior showed periodic oscillations of flow (turbulence) as seen in a real system.

Study of double exposure holography of the 3-dimensional character of the flow around an airfoil profile in a wind tunnel

NASA Technical Reports Server (NTRS)

Heid, G.; Stanislas, M.

1986-01-01

The tridimensional character of the flow around a profile placed between walls is demonstrated and the incidence induced with the assistance of measurements of velocities by double exposure holography is evaluated. The values obtained by the theory of Menard are compared satisfactorily to the values obtained by this experiment.

Numerical prediction of Pelton turbine efficiency

NASA Astrophysics Data System (ADS)

Jošt, D.; Mežnar, P.; Lipej, A.

2010-08-01

This paper presents a numerical analysis of flow in a 2 jet Pelton turbine with horizontal axis. The analysis was done for the model at several operating points in different operating regimes. The results were compared to the results of a test of the model. Analysis was performed using ANSYS CFX-12.1 computer code. A k-ω SST turbulent model was used. Free surface flow was modelled by two-phase homogeneous model. At first, a steady state analysis of flow in the distributor with two injectors was performed for several needle strokes. This provided us with data on flow energy losses in the distributor and the shape and velocity of jets. The second step was an unsteady analysis of the runner with jets. Torque on the shaft was then calculated from pressure distribution data. Averaged torque values are smaller than measured ones. Consequently, calculated turbine efficiency is also smaller than the measured values, the difference is about 4 %. The shape of the efficiency diagram conforms well to the measurements.

Can Seismic Observations of Bed Conditions on Ice Streams Help Constrain Parameters in Ice Flow Models?

NASA Astrophysics Data System (ADS)

Kyrke-Smith, Teresa M.; Gudmundsson, G. Hilmar; Farrell, Patrick E.

2017-11-01

We investigate correlations between seismically derived estimates of basal acoustic impedance and basal slipperiness values obtained from a surface-to-bed inversion using a Stokes ice flow model. Using high-resolution measurements along several seismic profiles on Pine Island Glacier (PIG), we find no significant correlation at kilometer scale between acoustic impedance and either retrieved basal slipperiness or basal drag. However, there is a stronger correlation when comparing average values along the individual profiles. We hypothesize that the correlation appears at the length scales over which basal variations are important to large-scale ice sheet flow. Although the seismic technique is sensitive to the material properties of the bed, at present there is no clear way of incorporating high-resolution seismic measurements of bed properties on ice streams into ice flow models. We conclude that more theoretical work needs to be done before constraints on mechanical conditions at the ice-bed interface from acoustic impedance measurements can be of direct use to ice sheet models.

Determination of the air w-value in proton beams using ionization chambers with gas flow capability.

PubMed

Moyers, M F; Vatnitsky, S M; Miller, D W; Slater, J M

2000-10-01

The purpose of this work was to determine the w-value of air for protons using the paired gas method. Several plastic- and magnesium-walled chambers were used with air, synthetic air, nitrogen, and argon flowing gases. Using argon as a reference gas, the w-value of air was measured and ranged from 32.7 to 34.5 J/C for protons with energies encountered in radiotherapy. Using nitrogen as a reference gas, the w-value of air ranged from 35.2 to 35.4 J/C over the same range of proton energies. The w-value was found, at a given energy, to be independent of the ion chamber used. The uncertainty in these measurements was estimated at 5.2% at the 2sigma level. This uncertainty was dominated by the 4.4% uncertainty in the w-value of the reference gas.

VARTM Process Modeling of Aerospace Composite Structures

NASA Technical Reports Server (NTRS)

Song, Xiao-Lan; Grimsley, Brian W.; Hubert, Pascal; Cano, Roberto J.; Loos, Alfred C.

2003-01-01

A three-dimensional model was developed to simulate the VARTM composite manufacturing process. The model considers the two important mechanisms that occur during the process: resin flow, and compaction and relaxation of the preform. The model was used to simulate infiltration of a carbon preform with an epoxy resin by the VARTM process. The model predicted flow patterns and preform thickness changes agreed qualitatively with the measured values. However, the predicted total infiltration times were much longer than measured most likely due to the inaccurate preform permeability values used in the simulation.

Prediction of alpha factor values for fine pore aeration systems.

PubMed

Gillot, S; Héduit, A

2008-01-01

The objective of this work was to analyse the impact of different geometric and operating parameters on the alpha factor value for fine bubble aeration systems equipped with EPDM membrane diffusers. Measurements have been performed on nitrifying plants operating under extended aeration and treating mainly domestic wastewater. Measurements performed on 14 nitrifying plants showed that, for domestic wastewater treatment under very low F/M ratios, the alpha factor is comprised between 0.44 and 0.98. A new composite variable (the Equivalent Contact Time, ECT) has been defined and makes it possible for a given aeration tank, knowing the MCRT, the clean water oxygen transfer coefficient and the supplied air flow rate, to predict the alpha factor value. ECT combines the effect on mass transfer of all generally accepted factors affecting oxygen transfer performances (air flow rate, diffuser submergence, horizontal flow). (c) IWA Publishing 2008.

Problems with indirect determinations of peak streamflows in steep, desert stream channels

USGS Publications Warehouse

Glancy, Patrick A.; Williams, Rhea P.

1994-01-01

Many peak streamflow values used in flood analyses for desert areas are derived using the Manning equation. Data used in the equation are collected after the flow has subsided, and peak flow is thereby determined indirectly. Most measurement problems and associated errors in peak-flow determinations result from (1) channel erosion or deposition that cannot be discerned or properly evaluated after the fact, (2) unsteady and non-uniform flow that rapidly changes in magnitude, and (3) appreciable sediment transport that has unknown effects on energy dissipation. High calculated velocities and Froude numbers are unacceptable to some investigators. Measurement results could be improved by recording flows with a video camera, installing a recording stream gage and recording rain gages, measuring channel scour with buried chains, analyzing measured data by multiple techniques, and supplementing indirect measurements with direct measurements of stream velocities in similar ephemeral streams.

Device and method for measuring the energy content of hot and humid air streams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosen, H. N.; Girod, G. F.; Kent, A. C.

1985-12-24

a portable device and method for measuring enthalpy and humidity of humid air from a space or flow channel at temperatures from 80/sup 0/ to 400/sup 0/ F. is described. the device consists of a psychrometer for measuring wet-bulb temperature, a vacuum pump for inducing sample air flow through the unit, a water-heating system for accurate psychrometer readings, an electronic computer system for evaluation of enthalpy and humidity from corrected and averaged values of wet- and dry- bulb temperatures, and a monitor for displaying the values. The device is programmable by the user to modify evaluation methods as necessary.

Near-infrared spectroscopy assessment of cerebral oxygen metabolism in the developing premature brain.

PubMed

Roche-Labarbe, Nadège; Fenoglio, Angela; Aggarwal, Alpna; Dehaes, Mathieu; Carp, Stefan A; Franceschini, Maria Angela; Grant, Patricia Ellen

2012-03-01

Little is known about cerebral blood flow, cerebral blood volume (CBV), oxygenation, and oxygen consumption in the premature newborn brain. We combined quantitative frequency-domain near-infrared spectroscopy measures of cerebral hemoglobin oxygenation (SO(2)) and CBV with diffusion correlation spectroscopy measures of cerebral blood flow index (BF(ix)) to determine the relationship between these measures, gestational age at birth (GA), and chronological age. We followed 56 neonates of various GA once a week during their hospital stay. We provide absolute values of SO(2) and CBV, relative values of BF(ix), and relative cerebral metabolic rate of oxygen (rCMRO(2)) as a function of postmenstrual age (PMA) and chronological age for four GA groups. SO(2) correlates with chronological age (r=-0.54, P value ≤0.001) but not with PMA (r=-0.07), whereas BF(ix) and rCMRO(2) correlate better with PMA (r=0.37 and 0.43, respectively, P value ≤0.001). Relative CMRO2 during the first month of life is lower when GA is lower. Blood flow index and rCMRO(2) are more accurate biomarkers of the brain development than SO(2) in the premature newborns.

Pulsatility index variations using two different transit-time flowmeters in coronary artery bypass surgery.

PubMed

Nordgaard, Håvard B; Vitale, Nicola; Astudillo, Rafael; Renzulli, Attilio; Romundstad, Pål; Haaverstad, Rune

2010-05-01

Transit-time flow measurement is widely accepted as an intra-operative assessment in coronary artery bypass grafting (CABG). However, the two most commonly applied flowmeters, manufactured by MediStim ASA and Transonic Inc., have different default filter settings of 20 and 10 Hz, respectively. This may cause different flow measurements, which will influence the reported results. The aim was to compare pulsatility index (PI) values recorded by the MediStim and Transonic flowmeters in two different clinical settings: (1) analysis of the flow patterns recorded simultaneously by both flowmeters in the same CABGs; and (2) evaluation of flow patterns under different levels of filter settings in the same grafts. Graft flow and PI were measured using the two different flowmeters simultaneously in 19 bypass grafts. Finally, eight grafts were assessed under different digital filter settings at 5, 10, 20, 30, 50 and 100 Hz. The Transonic flowmeter provided substantially lower PI as compared with the MediStim flowmeter. By increasing the filter setting in the flowmeter, PI increased considerably. The Transonic flowmeter displayed a lower PI than the MediStim, due to a lower filter setting. In the Transonic,flow signals are filtered at a lower level, rendering a 'smoother' pattern of flow curves. Because different filter settings determine different PIs, caution must be taken when flow values and flowmeters are compared. The type of flowmeter should be indicated whenever graft flow measurements and derived indexes are provided [corrected]. Copyright 2009 European Association for Cardio-Thoracic Surgery. All rights reserved.

Validation of the flow-through chamber (FTC) and steady-state (SS) methods for clearance rate measurements in bivalves

PubMed Central

Larsen, Poul S.; Riisgård, Hans Ulrik

2012-01-01

Summary To obtain precise and reliable laboratory clearance rate (filtration rate) measurements with the ‘flow-through chamber method’ (FTC) the design must ensure that only inflow water reaches the bivalve's inhalant aperture and that exit flow is fully mixed. As earlier recommended these prerequisites can be checked by a plot of clearance rate (CR) versus increasing through-flow (Fl) to reach a plateau, which is the true CR, but we also recommend to plot percent particles cleared versus reciprocal through-flow where the plateau becomes the straight line CR/Fl, and we emphasize that the percent of particles cleared is in itself neither a criterion for valid CR measurement, nor an indicator of appropriate ‘chamber geometry’ as hitherto adapted in many studies. For the ‘steady-state method’ (SS), the design must ensure that inflow water becomes fully mixed with the bivalve's excurrent flow to establish a uniform chamber concentration prevailing at its incurrent flow and at the chamber outlet. These prerequisites can be checked by a plot of CR versus increasing Fl, which should give the true CR at all through-flows. Theoretically, the experimental uncertainty of CR for a given accuracy of concentration measurements depends on the percent reduction in particle concentration (100×P) from inlet to outlet of the ideal ‘chamber geomety’. For FTC, it decreases with increasing values of P while for SS it first decreases but then increases again, suggesting the use of an intermediate value of P. In practice, the optimal value of P may depend on the given ‘chamber geometry’. The fundamental differences between the FTC and the SS methods and practical guidelines for their use are pointed out, and new data on CR for the blue mussel, Mytilus edulis, illustrate a design and use of the SS method which may be employed in e.g. long-term growth experiments at constant algal concentrations. PMID:23213362

Multibreath alveolar oxygen tension imaging.

PubMed

Clapp, Justin; Hamedani, Hooman; Kadlecek, Stephen; Xin, Yi; Shaghaghi, Hoora; Siddiqui, Sarmad; Rossman, Milton D; Rizi, Rahim R

2016-10-01

This study tested the ability of a multibreath hyperpolarized HP (3) He MRI protocol to increase the accuracy of regional alveolar oxygen tension (PA O2 ) measurements by lessening the influence of gas-flow artifacts. Conventional single-breath PA O2 measurement has been susceptible to error induced by intervoxel gas flow, particularly when used to study subjects with moderate-to-severe chronic obstructive pulmonary disease (COPD). Both single-breath and multibreath PA O2 imaging schemes were implemented in seven human subjects (one healthy, three asymptomatic smokers, and three COPD). The number and location of voxels with nonphysiologic PA O2 values generated by intervoxel gas flow were compared between the two protocols. The multibreath scheme resulted in a significantly lower total percentage of nonphysiologic PA O2 values (6.0%) than the single-breath scheme (13.7%) (P = 0.006). PA O2 maps showed several patterns of gas-flow artifacts that were present in the single-breath protocol but mitigated by the multibreath approach. Multibreath imaging also allowed for the analysis of slow-filling areas that presented no signal after a single breath. A multibreath approach enhances the accuracy and completeness of noninvasive PA O2 measurement by significantly lessening the proportion of nonphysiologic values generated by intervoxel gas flow. Magn Reson Med 76:1092-1101, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Surface roughness of flowable resin composites eroded by acidic and alcoholic drinks

PubMed Central

Poggio, Claudio; Dagna, Alberto; Chiesa, Marco; Colombo, Marco; Scribante, Andrea

2012-01-01

Aim: The aim of this study is to evaluate the surface roughness of four flowable resin composites following exposure to acidic and alcoholic drinks. Materials and Methods: SureFil SDR flow, TetricEvoFlow, Esthet-X Flow and Amaris Flow HT samples were immersed in artificial saliva, Coca Cola and Chivas Regal Whisky. Each specimen was examined using a Leica DCM 3D microscope: Arithmetical mean height of the surface profiles was measured (Sa). Results: Kruskal-Wallis test showed significant differences among various groups (P<0,001). Mann Whitney test was applied and control groups showed significantly lower Sa values than other groups (P=0,008). Coca Cola groups showed highest Sa values (P<0,021). No significant differences (P=0,14) in surface texture were found among the specimens of the different materials. No significant differences were found among TetricEvoFlow, Esthet-X Flow and Amaris Flow under control conditions nor after Coca Cola application. Under control condition and after Coca Cola application SureFil SDR flow showed significantly higher Sa values. Moreover, after whisky application Amaris Flow showed significantly lower Sa values then the other three groups that showed no significant differences among them. Conclusions: Acidic and alcoholic drinks eroded the surface roughness of all evaluated flowable resin composites. PMID:22557811

Modeling preferential water flow and solute transport in unsaturated soil using the active region model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng, F.; Wang, K.; Zhang, R.

2009-03-15

Preferential flow and solute transport are common processes in the unsaturated soil, in which distributions of soil water content and solute concentrations are often characterized as fractal patterns. An active region model (ARM) was recently proposed to describe the preferential flow and transport patterns. In this study, ARM governing equations were derived to model the preferential soil water flow and solute transport processes. To evaluate the ARM equations, dye infiltration experiments were conducted, in which distributions of soil water content and Cl{sup -} concentration were measured. Predicted results using the ARM and the mobile-immobile region model (MIM) were compared withmore » the measured distributions of soil water content and Cl{sup -} concentration. Although both the ARM and the MIM are two-region models, they are fundamental different in terms of treatments of the flow region. The models were evaluated based on the modeling efficiency (ME). The MIM provided relatively poor prediction results of the preferential flow and transport with negative ME values or positive ME values less than 0.4. On the contrary, predicted distributions of soil water content and Cl- concentration using the ARM agreed reasonably well with the experimental data with ME values higher than 0.8. The results indicated that the ARM successfully captured the macroscopic behavior of preferential flow and solute transport in the unsaturated soil.« less

Flow-field measurements in the windward surface shock layer of space shuttle orbiter configurations at Mach number 8. [wind tunnel tests of scale models

NASA Technical Reports Server (NTRS)

Martindale, W. R.; Carter, L. D.

1975-01-01

Pitot pressure and total-temperature measurements were made in the windward surface shock layer of two 0.0175-scale space shuttle orbiter models at simulated re-entry conditions. Corresponding surface static pressure measurements were also made. Flow properties at the edge of the model boundary layer were derived from these measurements and compared with values calculated using conventional methods.

U-values of flat and domed skylights

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klems, Joseph H.

1999-10-01

Data from nighttime measurements of the net heat flow through several types of skylights is presented. A well-known thermal test facility was reconfigured to measure the net heat flow through the bottom of a skylight/light well combination. Use of this data to determine the U-factor of the skylight is considerably more complicated than the analogous problem of a vertical fenestration contained in a test mask. Correction of the data for heat flow through the skylight well surfaces and evidence for the nature of the heat transfer between the skylight and the bottom of the well is discussed. The resulting measuredmore » U-values are presented and compared with calculations using the WINDOW4 and THERM programs.« less

Using a reactive transport model to elucidate differences between laboratory and field dissolution rates in regolith

NASA Astrophysics Data System (ADS)

Moore, Joel; Lichtner, Peter C.; White, Art F.; Brantley, Susan L.

2012-09-01

The reactive transport model FLOTRAN was used to forward-model weathering profiles developed on granitic outwash alluvium over 40-3000 ka from the Merced, California (USA) chronosequence as well as deep granitic regolith developed over 800 ka near Davis Run, Virginia (USA). Baseline model predictions that used laboratory rate constants (km), measured fluid flow velocities (v), and BET volumetric surface areas for the parent material (AB,mo) were not consistent with measured profiles of plagioclase, potassium feldspar, and quartz. Reaction fronts predicted by the baseline model are deeper and thinner than the observed, consistent with faster rates of reaction in the model. Reaction front depth in the model depended mostly upon saturated versus unsaturated hydrologic flow conditions, rate constants controlling precipitation of secondary minerals, and the average fluid flow velocity (va). Unsaturated hydrologic flow conditions (relatively open with respect to CO2(g)) resulted in the prediction of deeper reaction fronts and significant differences in the separation between plagioclase and potassium feldspar reaction fronts compared to saturated hydrologic flow (relatively closed with respect to CO2(g)). Under saturated or unsaturated flow conditions, the rate constant that controls precipitation rates of secondary minerals must be reduced relative to laboratory rate constants to match observed reaction front depths and measured pore water chemistry. Additionally, to match the observed reaction front depths, va was set lower than the measured value, v, for three of the four profiles. The reaction front gradients in mineralogy and pore fluid chemistry could only be modeled accurately by adjusting values of the product kmAB,mo. By assuming km values were constrained by laboratory data, field observations were modeled successfully with TST-like rate equations by dividing measured values of AB,mo by factors from 50 to 1700. Alternately, with sigmoidal or Al-inhibition rate models, this adjustment factor ranges from 5 to 170. Best-fit models of the wetter, hydrologically saturated Davis Run profile required a smaller adjustment to AB,mo than the drier hydrologically unsaturated Merced profiles. We attributed the need for large adjustments in va and AB,mo necessary for the Merced models to more complex hydrologic flow that decreased the reactive surface area in contact with bulk flow water, e.g., dead-end pore spaces containing fluids that are near or at chemical equilibrium. Thus, rate models from the laboratory can successfully predict weathering over millions of years, but work is needed to understand how to incorporate changes in what controls the relationship between reactive surface area and hydrologic flow.

Heat flow, morphology, pore fluids and hydrothermal circulation in a typical Mid-Atlantic Ridge flank near Oceanographer Fracture Zone

NASA Astrophysics Data System (ADS)

Le Gal, V.; Lucazeau, F.; Cannat, M.; Poort, J.; Monnin, C.; Battani, A.; Fontaine, F.; Goutorbe, B.; Rolandone, F.; Poitou, C.; Blanc-Valleron, M.-M.; Piedade, A.; Hipólito, A.

2018-01-01

Hydrothermal circulation affects heat and mass transfers in the oceanic lithosphere, not only at the ridge axis but also on their flanks, where the magnitude of this process has been related to sediment blanket and seamounts density. This was documented in several areas of the Pacific Ocean by heat flow measurements and pore water analysis. However, as the morphology of Atlantic and Indian ridge flanks is generally rougher than in the Pacific, these regions of slow and ultra-slow accretion may be affected by hydrothermal processes of different regimes. We carried out a survey of two regions on the eastern and western flanks of the Mid-Atlantic Ridge between Oceanographer and Hayes fracture zones. Two hundred and eight new heat flow measurements were obtained along six seismic profiles, on 5 to 14 Ma old seafloor. Thirty sediment cores (from which porewaters have been extracted) have been collected with a Kullenberg corer equipped with thermistors thus allowing simultaneous heat flow measurement. Most heat flow values are lower than those predicted by purely conductive cooling models, with some local variations and exceptions: heat flow values on the eastern flank of the study area are more variable than on the western flank, where they tend to increase westward as the sedimentary cover in the basins becomes thicker and more continuous. Heat flow is also higher, on average, on the northern sides of both the western and eastern field regions and includes values close to conductive predictions near the Oceanographer Fracture Zone. All the sediment porewaters have a chemical composition similar to that of bottom seawater (no anomaly linked to fluid circulation has been detected). Heat flow values and pore fluid compositions are consistent with fluid circulation in volcanic rocks below the sediment. The short distances between seamounts and short fluid pathways explain that fluids flowing in the basaltic aquifer below the sediment have remained cool and unaltered. Finally, relief at small-scale is calculated using variogram of bathymetry and compared for different regions affected by hydrothermal circulation.

Effect of grazing flow on the acoustic impedance of Helmholtz resonators consisting of single and clustered orifices

NASA Technical Reports Server (NTRS)

Hersch, A. S.; Walker, B.

1979-01-01

A semiempirical fluid mechanical model is derived for the acoustic behavior of thin-walled single orifice Helmholtz resonators in a grazing flow environment. The incident and cavity sound fields are connected in terms of an orifice discharge coefficient whose values are determined experimentally using the two-microphone method. Measurements show that at high grazing flow speeds, acoustical resistance is almost linearly proportional to the grazing flow speed and almost independent of incident sound pressure. The corresponding values of reactance are much smaller and tend towards zero. For thicker-walled orifice plates, resistance and reactance were observed to be less sensitive to grazing flow as the ratio of plate thickness to orifice diameter increased. Loud tones were observed to radiate from a single orifice Helmholtz resonator due to interaction between the grazing flow shear layer and the resonator cavity. Measurements showed that the tones radiated at a Strouhal number equal to 0.26. The effects of grazing flow on the impedance of Helmholtz resonators consisting of clusters of orifices was also studied. In general, both resistance and reaction were found to be virtually independent of orifice relative spacing and number. These findings are valid with and without grazing flow.

Design and numerical simulation on an auto-cumulative flowmeter in horizontal oil-water two-phase flow

NASA Astrophysics Data System (ADS)

Xie, Beibei; Kong, Lingfu; Kong, Deming; Kong, Weihang; Li, Lei; Liu, Xingbin; Chen, Jiliang

2017-11-01

In order to accurately measure the flow rate under the low yield horizontal well conditions, an auto-cumulative flowmeter (ACF) was proposed. Using the proposed flowmeter, the oil flow rate in horizontal oil-water two-phase segregated flow can be finely extracted. The computational fluid dynamics software Fluent was used to simulate the fluid of the ACF in oil-water two-phase flow. In order to calibrate the simulation measurement of the ACF, a novel oil flow rate measurement method was further proposed. The models of the ACF were simulated to obtain and calibrate the oil flow rate under different total flow rates and oil cuts. Using the finite-element method, the structure of the seven conductance probes in the ACF was simulated. The response values for the probes of the ACF under the conditions of oil-water segregated flow were obtained. The experiments for oil-water segregated flow under different heights of the oil accumulation in horizontal oil-water two-phase flow were carried out to calibrate the ACF. The validity of the oil flow rate measurement in horizontal oil-water two-phase flow was verified by simulation and experimental results.

Design and numerical simulation on an auto-cumulative flowmeter in horizontal oil-water two-phase flow.

PubMed

Xie, Beibei; Kong, Lingfu; Kong, Deming; Kong, Weihang; Li, Lei; Liu, Xingbin; Chen, Jiliang

2017-11-01

In order to accurately measure the flow rate under the low yield horizontal well conditions, an auto-cumulative flowmeter (ACF) was proposed. Using the proposed flowmeter, the oil flow rate in horizontal oil-water two-phase segregated flow can be finely extracted. The computational fluid dynamics software Fluent was used to simulate the fluid of the ACF in oil-water two-phase flow. In order to calibrate the simulation measurement of the ACF, a novel oil flow rate measurement method was further proposed. The models of the ACF were simulated to obtain and calibrate the oil flow rate under different total flow rates and oil cuts. Using the finite-element method, the structure of the seven conductance probes in the ACF was simulated. The response values for the probes of the ACF under the conditions of oil-water segregated flow were obtained. The experiments for oil-water segregated flow under different heights of the oil accumulation in horizontal oil-water two-phase flow were carried out to calibrate the ACF. The validity of the oil flow rate measurement in horizontal oil-water two-phase flow was verified by simulation and experimental results.

Optical tweezers for measuring the interaction of the two single red blood cells in flow condition

NASA Astrophysics Data System (ADS)

Lee, Kisung; Muravyov, Alexei; Semenov, Alexei; Wagner, Christian; Priezzhev, Alexander

2017-03-01

Aggregation of red blood cells (RBCs) is an intrinsic property of blood, which has direct effect on the blood viscosity and therefore affects overall the blood circulation throughout the body. It is attracting interest for the research in both fundamental science and clinical application. Despite of the intensive research, the aggregation mechanism is remaining not fully clear. Recent advances in methods allowed measuring the interaction between single RBCs in a well-defined configuration leading the better understanding of the mechanism of the process. However the most of the studies were made on the static cells. Thus, the measurements in flow mimicking conditions are missing. In this work, we aim to study the interaction of two RBCs in the flow conditions. We demonstrate the characterization of the cells interaction strength (or flow tolerance) by measuring the flow velocity to be applied to separate two aggregated cells trapped by double channel optical tweezers in a desired configuration. The age-separated cells were used for this study. The obtained values for the minimum flow velocities needed to separate the two cells were found to be 78.9 +/- 6.1 μm/s and 110 +/- 13 μm/s for old and young cells respectively. The data obtained is in agreement with the observations reported by other authors. The significance of our results is in ability for obtaining a comprehensible and absolute physical value characterizing the cells interaction in flow conditions (not like the Aggregation Index measured in whole blood suspensions by other techniques, which is some abstract parameter)

Comparison of Two Acoustic Waveguide Methods for Determining Liner Impedance

NASA Technical Reports Server (NTRS)

Jones, Michael G.; Watson, Willie R.; Tracy, Maureen B.; Parrott, Tony L.

2001-01-01

Acoustic measurements taken in a flow impedance tube are used to assess the relative accuracy of two waveguide methods for impedance eduction in the presence of grazing flow. The aeroacoustic environment is assumed to contain forward and backward-traveling acoustic waves, consisting of multiple modes, and uniform mean flow. Both methods require a measurement of the complex acoustic pressure profile over the length of the test liner. The Single Mode Method assumes that the sound pressure level and phase decay-rates of a single progressive mode can be extracted from this measured complex acoustic pressure profile. No a priori assumptions are made in the Finite Element. Method regarding the modal or reflection content in the measured acoustic pressure profile. The integrity of each method is initially demonstrated by how well their no-flow impedances match those acquired in a normal incidence impedance tube. These tests were conducted using ceramic tubular and conventional perforate liners. Ceramic tubular liners were included because of their impedance insensitivity to mean flow effects. Conversely, the conventional perforate liner was included because its impedance is known to be sensitive to mean flow velocity effects. Excellent comparisons between impedance values educed with the two waveguide methods in the absence of mean flow and the corresponding values educed with the normal incident impedance tube were observed. The two methods are then compared for mean flow Mach numbers up to 0.5, and are shown to give consistent results for both types of test liners. The quality of the results indicates that the Single Mode Method should be used when the measured acoustic pressure profile is clearly dominated by a single progressive mode, and the Finite Element Method should be used for all other cases.

Further experiments for mean velocity profile of pipe flow at high Reynolds number

NASA Astrophysics Data System (ADS)

Furuichi, N.; Terao, Y.; Wada, Y.; Tsuji, Y.

2018-05-01

This paper reports further experimental results obtained in high Reynolds number actual flow facility in Japan. The experiments were performed in a pipe flow with water, and the friction Reynolds number was varied up to Reτ = 5.3 × 104. This high Reynolds number was achieved by using water as the working fluid and adopting a large-diameter pipe (387 mm) while controlling the flow rate and temperature with high accuracy and precision. The streamwise velocity was measured by laser Doppler velocimetry close to the wall, and the mean velocity profile, called log-law profile U+ = (1/κ) ln(y+) + B, is especially focused. After careful verification of the mean velocity profiles in terms of the flow rate accuracy and an evaluation of the consistency of the present results with those from previously measurements in a smaller pipe (100 mm), it was found that the value of κ asymptotically approaches a constant value of κ = 0.384.

Changes of the corrosion potential of iron in stagnation and flow conditions and their relationship with metal release.

PubMed

Fabbricino, Massimiliano; Korshin, Gregory V

2014-10-01

This study examined the behavior of corrosion potential (Ecorr) of iron exposed to drinking water during episodes of stagnation and flow. These measurements showed that during stagnation episodes, Ecorr values decrease prominently and consistently. This decrease is initially rapid but it becomes slower as the stagnation time increases. During flow episodes, the Ecorr values increase and reach a quasi-steady state. Experiments with varying concentrations of dissolved oxygen showed that the decrease of Ecorr values characteristic for stagnation is likely to be associated with the consumption of dissolved oxygen by the exposed metal. The corrosion potential of iron and its changes during stagnation were sensitive to the concentrations of sulfate and chloride ions. Measurements of iron release showed that both the absolute values of Ecorr measured prior to or after stagnation episodes were well correlated with the logarithms of concentrations of total iron. The slope of this dependence showed that the observed correlations between Ecorr values and Fe concentrations corresponded to the coupling between the oxidant consumption and changes of Fe redox status. These results demonstrate that in situ Ecorr measurements can be a sensitive method with which to ascertain effects of hydrodynamic conditions and short-term variations of water chemistry on metal release and corrosion in drinking water. This approach is valuable practically because Ecorr measurements are precise, can be carried out in situ with any desired time resolution, do not affect the state of exposed surface in any extent and can be carried out with readily available equipment. Copyright © 2014 Elsevier Ltd. All rights reserved.

New diesel injection nozzle flow measuring device

NASA Astrophysics Data System (ADS)

Marčič, Milan

2000-04-01

A new measuring device has been developed for diesel injection nozzle testing, allowing measuring of the steady flow through injection nozzle and the injection rate. It can be best applied for measuring the low and high injection rates of the pintle and single hole nozzle. In steady flow measuring the fuel pressure at the inlet of the injection nozzle is 400 bar. The sensor of the measuring device measures the fuel charge, resulting from fuel rubbing in the fuel injection system, as well as from the temperature gradient in the sensor electrode. The electric charge is led to the charge amplifier, where it is converted into electric current and amplified. The amplifier can be used also to measure the mean injection rate value.

Extreme value statistics and finite-size scaling at the ecological extinction/laminar-turbulence transition

NASA Astrophysics Data System (ADS)

Shih, Hong-Yan; Goldenfeld, Nigel

Experiments on transitional turbulence in pipe flow seem to show that turbulence is a transient metastable state since the measured mean lifetime of turbulence puffs does not diverge asymptotically at a critical Reynolds number. Yet measurements reveal that the lifetime scales with Reynolds number in a super-exponential way reminiscent of extreme value statistics, and simulations and experiments in Couette and channel flow exhibit directed percolation type scaling phenomena near a well-defined transition. This universality class arises from the interplay between small-scale turbulence and a large-scale collective zonal flow, which exhibit predator-prey behavior. Why is asymptotically divergent behavior not observed? Using directed percolation and a stochastic individual level model of predator-prey dynamics related to transitional turbulence, we investigate the relation between extreme value statistics and power law critical behavior, and show that the paradox is resolved by carefully defining what is measured in the experiments. We theoretically derive the super-exponential scaling law, and using finite-size scaling, show how the same data can give both super-exponential behavior and power-law critical scaling.

Skin-friction gauge for use in hypervelocity impulse facilities

NASA Technical Reports Server (NTRS)

Kelly, G. M.; Simmons, J. M.; Paull, A.

1992-01-01

A transducer is presented which can measure as rise-time of about 20 microsec, and is thereby applicable to measurements in the high-enthalpy flows associated with hypervelocity impulse facilities. Results are presented which demonstrate the effectiveness of the concept in the case of skin-friction measurements conducted on a flat plate at Mach 3.2. The calibration used was against theoretical skin-friction values in a simple flow.

Color Doppler ultrasound evaluation of testicular blood flow in stallions.

PubMed

Pozor, M A; McDonnell, S M

2004-04-01

The objectives of this study were to evaluate the potential use of color Doppler ultrasound to characterize blood flow to the stallion testis, and to establish reference values for Doppler measures of blood flow in the testicular artery of the stallion. Both testes from each of 52 horses were examined using a pulsed-wave color Doppler ultrasound with a sector array 5/7.5 MHz transducer with a 1mm gate setting. Peak systolic velocity (PSV), end diastolic velocity (EDV), resistive index (RI), and pulsatility index (PI) of the testicular artery were measured in each of two locations, the convoluted aspect (spermatic cord) and the marginal aspect of the artery (on the epididymal edge of testis). We found that: (1) all measures were obtainable; (2) except for EDV, the majority of the measures were higher at the cord location than at the marginal aspect of the artery (P < 0.05); and (3) measures for left and right testes were similar (P > 0.10). Resulting measures from 41 of these stallions (82 testes) that appeared free of testicular pathology provide useful reference values for clinical evaluation. Evaluation of 11 cases with testicular pathology suggested further investigation of possible effects of these various conditions on testicular blood flow and testicular function.

Wind-Tunnel Investigation of Control-Surface Characteristics XX : Plain and Balanced Flaps on an NACA 0009 Rectangular Semispan Tail Surface

NASA Technical Reports Server (NTRS)

Garner, Elizabeth I.

1944-01-01

Correlation is established between aerodynamic characteristics of control surfaces in two-dimensional and three-dimensional flow. Slope of lift curve was affected little by overhang and balance-nose shape, but increased by sealing flap-nose gap. Effectiveness of balancing tab was same for sealed plain flap and unsealed overhang flap. Changes in hinge-moment coefficient were diminished by sealing gap. Values measured by three-dimensional flow disagreed with two-dimensional flow values until aspect ratio corrections were made.

Numerical Simulation of Two Dimensional Flows in Yazidang Reservoir

NASA Astrophysics Data System (ADS)

Huang, Lingxiao; Liu, Libo; Sun, Xuehong; Zheng, Lanxiang; Jing, Hefang; Zhang, Xuande; Li, Chunguang

2018-01-01

This paper studied the problem of water flow in the Yazid Ang reservoir. It built 2-D RNG turbulent model, rated the boundary conditions, used the finite volume method to discrete equations and divided the grid by the advancing-front method. It simulated the two conditions of reservoir flow field, compared the average vertical velocity of the simulated value and the measured value nearby the water inlet and the water intake. The results showed that the mathematical model could be applied to the similar industrial water reservoir.

40 CFR 1065.345 - Vacuum-side leak verification.

Code of Federal Regulations, 2011 CFR

2011-07-01

... zero flow, or by detecting the dilution of a known concentration of span gas when it flows through the.... Measure and record the absolute pressure of the trapped gas and optionally the system absolute temperature... pressure and optionally temperature. (4) Calculate the leak flow rate based on an assumed value of zero for...

40 CFR 1065.345 - Vacuum-side leak verification.

Code of Federal Regulations, 2014 CFR

2014-07-01

... zero flow, or by detecting the dilution of a known concentration of span gas when it flows through the.... Measure and record the absolute pressure of the trapped gas and optionally the system absolute temperature... pressure and optionally temperature. (4) Calculate the leak flow rate based on an assumed value of zero for...

40 CFR 1065.345 - Vacuum-side leak verification.

Code of Federal Regulations, 2013 CFR

2013-07-01

... zero flow, or by detecting the dilution of a known concentration of span gas when it flows through the.... Measure and record the absolute pressure of the trapped gas and optionally the system absolute temperature... pressure and optionally temperature. (4) Calculate the leak flow rate based on an assumed value of zero for...

40 CFR 1065.345 - Vacuum-side leak verification.

Code of Federal Regulations, 2010 CFR

2010-07-01

... zero flow, or by detecting the dilution of a known concentration of span gas when it flows through the.... Measure and record the absolute pressure of the trapped gas and optionally the system absolute temperature... pressure and optionally temperature. (4) Calculate the leak flow rate based on an assumed value of zero for...

40 CFR 1065.345 - Vacuum-side leak verification.

Code of Federal Regulations, 2012 CFR

2012-07-01

... zero flow, or by detecting the dilution of a known concentration of span gas when it flows through the.... Measure and record the absolute pressure of the trapped gas and optionally the system absolute temperature... pressure and optionally temperature. (4) Calculate the leak flow rate based on an assumed value of zero for...

Boundary layer separation and reattachment detection on airfoils by thermal flow sensors.

PubMed

Sturm, Hannes; Dumstorff, Gerrit; Busche, Peter; Westermann, Dieter; Lang, Walter

2012-10-24

A sensor concept for detection of boundary layer separation (flow separation, stall) and reattachment on airfoils is introduced in this paper. Boundary layer separation and reattachment are phenomena of fluid mechanics showing characteristics of extinction and even inversion of the flow velocity on an overflowed surface. The flow sensor used in this work is able to measure the flow velocity in terms of direction and quantity at the sensor's position and expected to determine those specific flow conditions. Therefore, an array of thermal flow sensors has been integrated (flush-mounted) on an airfoil and placed in a wind tunnel for measurement. Sensor signals have been recorded at different wind speeds and angles of attack for different positions on the airfoil. The sensors used here are based on the change of temperature distribution on a membrane (calorimetric principle). Thermopiles are used as temperature sensors in this approach offering a baseline free sensor signal, which is favorable for measurements at zero flow. Measurement results show clear separation points (zero flow) and even negative flow values (back flow) for all sensor positions. In addition to standard silicon-based flow sensors, a polymer-based flexible approach has been tested showing similar results.

Boundary Layer Separation and Reattachment Detection on Airfoils by Thermal Flow Sensors

PubMed Central

Sturm, Hannes; Dumstorff, Gerrit; Busche, Peter; Westermann, Dieter; Lang, Walter

2012-01-01

A sensor concept for detection of boundary layer separation (flow separation, stall) and reattachment on airfoils is introduced in this paper. Boundary layer separation and reattachment are phenomena of fluid mechanics showing characteristics of extinction and even inversion of the flow velocity on an overflowed surface. The flow sensor used in this work is able to measure the flow velocity in terms of direction and quantity at the sensor's position and expected to determine those specific flow conditions. Therefore, an array of thermal flow sensors has been integrated (flush-mounted) on an airfoil and placed in a wind tunnel for measurement. Sensor signals have been recorded at different wind speeds and angles of attack for different positions on the airfoil. The sensors used here are based on the change of temperature distribution on a membrane (calorimetric principle). Thermopiles are used as temperature sensors in this approach offering a baseline free sensor signal, which is favorable for measurements at zero flow. Measurement results show clear separation points (zero flow) and even negative flow values (back flow) for all sensor positions. In addition to standard silicon-based flow sensors, a polymer-based flexible approach has been tested showing similar results. PMID:23202160

Validation of a CFD Model by Using 3D Sonic Anemometers to Analyse the Air Velocity Generated by an Air-Assisted Sprayer Equipped with Two Axial Fans

PubMed Central

García-Ramos, F. Javier; Malón, Hugo; Aguirre, A. Javier; Boné, Antonio; Puyuelo, Javier; Vidal, Mariano

2015-01-01

A computational fluid dynamics (CFD) model of the air flow generated by an air-assisted sprayer equipped with two axial fans was developed and validated by practical experiments in the laboratory. The CFD model was developed by considering the total air flow supplied by the sprayer fan to be the main parameter, rather than the outlet air velocity. The model was developed for three air flows corresponding to three fan blade settings and assuming that the sprayer is stationary. Actual measurements of the air velocity near the sprayer were taken using 3D sonic anemometers. The workspace sprayer was divided into three sections, and the air velocity was measured in each section on both sides of the machine at a horizontal distance of 1.5, 2.5, and 3.5 m from the machine, and at heights of 1, 2, 3, and 4 m above the ground The coefficient of determination (R2) between the simulated and measured values was 0.859, which demonstrates a good correlation between the simulated and measured data. Considering the overall data, the air velocity values produced by the CFD model were not significantly different from the measured values. PMID:25621611

Validation of a CFD model by using 3D sonic anemometers to analyse the air velocity generated by an air-assisted sprayer equipped with two axial fans.

PubMed

García-Ramos, F Javier; Malón, Hugo; Aguirre, A Javier; Boné, Antonio; Puyuelo, Javier; Vidal, Mariano

2015-01-22

A computational fluid dynamics (CFD) model of the air flow generated by an air-assisted sprayer equipped with two axial fans was developed and validated by practical experiments in the laboratory. The CFD model was developed by considering the total air flow supplied by the sprayer fan to be the main parameter, rather than the outlet air velocity. The model was developed for three air flows corresponding to three fan blade settings and assuming that the sprayer is stationary. Actual measurements of the air velocity near the sprayer were taken using 3D sonic anemometers. The workspace sprayer was divided into three sections, and the air velocity was measured in each section on both sides of the machine at a horizontal distance of 1.5, 2.5, and 3.5 m from the machine, and at heights of 1, 2, 3, and 4 m above the ground The coefficient of determination (R2) between the simulated and measured values was 0.859, which demonstrates a good correlation between the simulated and measured data. Considering the overall data, the air velocity values produced by the CFD model were not significantly different from the measured values.

The effects of aortic coarctation on cerebral hemodynamics and its importance in the etiopathogenesis of intracranial aneurysms.

PubMed

Singh, Pankaj K; Marzo, Alberto; Staicu, Cristina; William, Matt G; Wilkinson, Iain; Lawford, Patricia V; Rufenacht, Daniel A; Bijlenga, Philippe; Frangi, Alejandro F; Hose, Rodney; Patel, Umang J; Coley, Stuart C

2010-01-01

Hemodynamic changes in the cerebral circulation in presence of coarctation of aorta (CoA) and their significance in the increased intracranial aneurysms (IAs) formation in these patients remain unclear. In the present study, we measured the flow-rate waveforms in the cerebral arteries of a patient with CoA, followed by an analysis of different hemodynamic indices in a coexisting IA. Phase-contrast Magnetic Resonance (pc-MR) volumetric flow-rate (VFR) measurements were performed in cerebral arteries of a 51 years old woman with coexisting CoA, and five healthy volunteers. Numerical predictions of a number of relevant hemodynamic indices were performed in an IA located in sub-clinoid part of left internal carotid artery (ICA) of the patient. Computations were performed using Ansys(®)-CFX(™) solver using the VFR values measured in the patient as boundary conditions (BCs). A second analysis was performed using the average VFR values measured in healthy volunteers. The VFR waveforms measured in the patient and healthy volunteers were compared followed by a comparison of the hemodynamic indices obtained using both approaches. The results are discussed in the background of relevant literature. Mean flow-rates were increased by 27.1% to 54.9% (2.66-5.44 ml/sec) in the cerebral circulation of patients with CoA as compared to healthy volunteers (1.2-3.95 ml/sec). Velocities were increased inside the IA by 35-45%. An exponential rise of 650% was observed in the area affected by high wall shear stress (WSS>15Pa) when flow-rates specific to CoA were used as compared to population average flow-rates. Absolute values of space and time averaged WSS were increased by 65%. Whereas values of maximum pressure on the IA wall were increased by 15% the area of elevated pressure was actually decreased by 50%, reflecting a more focalized jet impingement within the IA of the CoA patient. IAs can develop in patients with CoA several years after the surgical repair. Cerebral flow-rates in CoA patients are significantly higher as compared to average flow-rates in healthy population. The increased supra-physiological WSS (>15Pa), OSI (>0.2) and focalized pressure may play an important role in the etiopathogenesis of IAs in patients with CoA.

The Effects of Aortic Coarctation on Cerebral Hemodynamics and its Importance in the Etiopathogenesis of Intracranial Aneurysms

PubMed Central

Singh, Pankaj K; Marzo, Alberto; Staicu, Cristina; William, Matt G; Wilkinson, Iain; Lawford, Patricia V; Rufenacht, Daniel A; Bijlenga, Philippe; Frangi, Alejandro F; Hose, Rodney; Patel, Umang J; Coley, Stuart C

2010-01-01

Objectives: Hemodynamic changes in the cerebral circulation in presence of coarctation of aorta (CoA) and their significance in the increased intracranial aneurysms (IAs) formation in these patients remain unclear. In the present study, we measured the flow-rate waveforms in the cerebral arteries of a patient with CoA, followed by an analysis of different hemodynamic indices in a coexisting IA. Materials and Methods: Phase-contrast Magnetic Resonance (pc-MR) volumetric flow-rate (VFR) measurements were performed in cerebral arteries of a 51 years old woman with coexisting CoA, and five healthy volunteers. Numerical predictions of a number of relevant hemodynamic indices were performed in an IA located in sub-clinoid part of left internal carotid artery (ICA) of the patient. Computations were performed using Ansys®-CFX™ solver using the VFR values measured in the patient as boundary conditions (BCs). A second analysis was performed using the average VFR values measured in healthy volunteers. The VFR waveforms measured in the patient and healthy volunteers were compared followed by a comparison of the hemodynamic indices obtained using both approaches. The results are discussed in the background of relevant literature. Results: Mean flow-rates were increased by 27.1% to 54.9% (2.66–5.44 ml/sec) in the cerebral circulation of patients with CoA as compared to healthy volunteers (1.2–3.95 ml/sec). Velocities were increased inside the IA by 35–45%. An exponential rise of 650% was observed in the area affected by high wall shear stress (WSS>15Pa) when flow-rates specific to CoA were used as compared to population average flow-rates. Absolute values of space and time averaged WSS were increased by 65%. Whereas values of maximum pressure on the IA wall were increased by 15% the area of elevated pressure was actually decreased by 50%, reflecting a more focalized jet impingement within the IA of the CoA patient. Conclusions: IAs can develop in patients with CoA several years after the surgical repair. Cerebral flow-rates in CoA patients are significantly higher as compared to average flow-rates in healthy population. The increased supra-physiological WSS (>15Pa), OSI (>0.2) and focalized pressure may play an important role in the etiopathogenesis of IAs in patients with CoA. PMID:22518256

Heat flow and geothermal potential of the East Mesa KGRA, Imperial Valley, California

NASA Technical Reports Server (NTRS)

Swanberg, C. A.

1974-01-01

The East Mesa KGRA (Known Geothermal Resource Area) is located in the southeast part of the Imperial Valley, California, and is roughly 150 kilometers square in areal extent. A new heat flow technique which utilizes temperature gradient measurements across best clays is presented and shown to be as accurate as conventional methods for the present study area. Utilizing the best clay gradient technique, over 70 heat flow determinations have been completed within and around the East Mesa KGRA. Background heat flow values range from 1.4 to 2.4 hfu (1 hfu = .000001 cal. per square centimeter-second) and are typical of those throughout the Basin and Range province. Heat flow values for the northwest lobe of the KGRA (Mesa anomaly) are as high as 7.9 hfu, with the highest values located near gravity and seismic noise maxima and electrical resistivity minima. An excellent correlation exists between heat flow contours and faults defined by remote sensing and microearthquake monitoring.

Water Use in Wetland Kalo Cultivation in Hawai`i

USGS Publications Warehouse

Gingerich, Stephen B.; Yeung, Chiu W.; Ibarra, Tracy-Joy N.; Engott, John A.

2007-01-01

Ten cultivation areas (8 windward, 2 leeward) were selected for a kalo water-use study, primarily on the basis of the diversity of environmental and agricultural conditions under which wetland kalo is grown and landowner permission and availability. Flow and water-temperature data were collected at the lo`i complex level and at the individual lo`i level. To ensure that flow and temperature data collected at different lo`i reflect similar irrigation conditions (continuous flooding of the mature crop), only lo`i with crops near the harvesting stage were selected for water-temperature data collection. The water need for kalo cultivation varies depending on the crop stage. In this study, data were collected during the dry season (June-October), when water requirements for cooling kalo approach upper limits. Flow measurements generally were made during the warmest part of the day, and temperature measurements were made every 15 minutes at each site for about a two-month period. Flow and temperature data were collected from kalo cultivation areas on four islands - Kaua`i, O`ahu, Maui, and Hawai`i. The average inflow value for the 19 lo`i complexes measured in this study is 260,000 gallons per acre per day, and the median inflow value is 150,000 gallons per acre per day. The average inflow value for the 17 windward sites is 270,000 gallons per acre per day, and the median inflow value is 150,000 gallons per acre per day. The average inflow value for the two leeward sites is 150,000 gallons per acre per day. The average inflow value measured for six individual lo`i is 350,000 gallons per acre per day, and the median inflow value is 270,000 gallons per acre per day. The average inflow value for the five windward lo`i is 370,000 gallons per acre per day, and the median inflow value is 320,000 gallons per acre per day. The inflow value for the one leeward lo`i is 210,000 gallons per acre per day. These inflow values are consistent with previously reported values for inflow and are significantly higher than values generally estimated for water consumption during kalo cultivation. These measurements of inflow are important for future considerations of water-use requirements for successful kalo cultivation. Of the 17 lo`i complexes where water inflow temperature was measured, only 3 had inflow temperatures that rose above 27 ?C, the threshold temperature above which wetland kalo is more susceptible to fungi and associated rotting diseases. The coldest mean inflow temperature was 20.0 ?C and the warmest inflow temperature was 24.9 ?C. All 15 of the sites where outflow temperatures were measured had some temperatures greater than 27 ?C. Outflow temperatures exceeded 27 ?C between 2.5 percent and about 40 percent of the time. Mean outflow temperatures ranged from 23.0 ?C to 26.7 ?C.

A Comparative Study on Quantitative Assessment of Blood Flow and Vascularization in Polycystic Ovary Syndrome Patients and Normal Women Using Three-Dimensional Power Doppler Ultrasonography.

PubMed

Garg, Nitasha; Khaira, Harkiran Kaur; Kaur, Manjot; Sinha, Smita

2018-04-01

To compare the quantitative assessment of blood flow and vascularization of ovaries in polycystic ovary syndrome patients and normal women using three-dimensional power Doppler ultrasonography. This cross-sectional quantitative study was conducted on women of reproductive age group (15-45 years) attending Gynaecology OPD AIMSR, Bathinda, Punjab. Thirty women were enrolled in polycystic ovarian syndrome (PCOS) group and 30 healthy women in control group. Women were categorized as polycystic ovary syndrome according to Rotterdam's criteria. The women with PCOS underwent transvaginal USG Doppler on day 6 of the cycle using 3D power Doppler USG equipment (GE Voluson E8), and vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were measured. The mean values of VI, FI and VFI measured by power Doppler ultrasonography were significantly increased ( P value = 0.000) in women with PCOS when compared with healthy women. This study suggests that blood flow and vascularization measured by 3D power Doppler ultrasonography in ovaries of polycystic ovary syndrome patients were significantly more than the ovaries of normal women.

Glucose pump test can be used to measure blood flow rate of native arteriovenous fistula in chronic hemodialysis.

PubMed

Yavuz, Y C; Selcuk, N Y; Altıntepe, L; Güney, I; Yavuz, S

2018-01-01

In chronic hemodialysis patients, the low flow of vascular access may leads to inadequate dialysis, increased rate of hospitalization, morbidity, and mortality. It was found that surveillance should be performed for native arteriovenous (AV) should not be performed for AV graft in various studies. However, surveillance was done in graft AV fistulas in most studies. Doppler ultrasonography (US) was suggested for surveillance of AV fistulas by the last vascular access guideline of National Kidney Foundation Disease Outcomes Quality Initiative (NKF KDOQI). The aim of study is to determine whether glucose pump test (GPT) is used for surveillance of native AV fistulas by using Doppler US as reference. In 93 chronic hemodialysis patients with native AV fistula, blood flow rates were measured by Doppler US and GPT. For GPT, glucose was infused to 16 mL/min by pump and was measured at basal before the infusion and 11 s after the start of the infusion by glucometer. Doppler US was done by an expert radiologist. Used statistical tests were Mann-Whitney U test, Friedman test, regression analysis, and multiple regression analysis. Median values of blood flow rates measured by GPT (707 mL/min) and by Doppler US (700 mL/min) were not different (Z = 0.414, P = 0.678). Results of GPT and Doppler US measurements were positive correlate by regression analysis. The mean GPT value of diabetic patients (n = 39; 908 mL/min) was similar to that of nondiabetic patients (n = 54; 751 mL/min; Z = 1.31, P = 0.188). GPT values measured at three different dialysis session did not differ from each other that by Friedman test (F = 0.92, P = 0.39). This showed that GPT was stable and reliable. Glucose pump test can be used to measure blood flow rate of native AV fistula. GPT is an accurate and reliable test.

A comparison of daily water use estimates derived from constant-heat sap-flow probe values and gravimetric measurements in pot-grown saplings.

PubMed

McCulloh, Katherine A; Winter, Klaus; Meinzer, Frederick C; Garcia, Milton; Aranda, Jorge; Lachenbruch, Barbara

2007-09-01

Use of Granier-style heat dissipation sensors to measure sap flow is common in plant physiology, ecology and hydrology. There has been concern that any change to the original Granier design invalidates the empirical relationship between sap flux density and the temperature difference between the probes. Here, we compared daily water use estimates from gravimetric measurements with values from variable length heat dissipation sensors, which are a relatively new design. Values recorded during a one-week period were compared for three large pot-grown saplings of each of the tropical trees Pseudobombax septenatum (Jacq.) Dugand and Calophyllum longifolium Willd. For five of the six individuals, P values from paired t-tests comparing the two methods ranged from 0.12 to 0.43 and differences in estimates of total daily water use over the week of the experiment averaged < 3%. In one P. septenatum sapling, the sap flow sensors underestimated water use relative to the gravimetric measurements. This discrepancy could have been associated with naturally occurring gradients in temperature that reduced the difference in temperature between the probes, which would have caused the sensor method to underestimate water use. Our results indicate that substitution of variable length heat dissipation probes for probes of the original Granier design did not invalidate the empirical relationship determined by Granier between sap flux density and the temperature difference between probes.

Ocular blood flow values measured by laser speckle flowgraphy correlate with the postmenstrual age of normal neonates.

PubMed

Matsumoto, Tadashi; Itokawa, Takashi; Shiba, Tomoaki; Katayama, Yuuji; Arimura, Tetsushi; Hine, Kotaro; Mizukaki, Norio; Yoda, Hitoshi; Hori, Yuichi

2016-08-01

To evaluate the relationships between optic nerve head (ONH) blood flow by laser speckle flowgraphy (LSFG), and postmenstrual age and body weight in normal neonates. During their normal sleep, we studied 24 infants (postmenstrual age, 248-295 days) whose ocular blood flow could be measured three consecutive times. While the subjects slept in the supine position, three mean blur rate (MBR) values of the ONH were obtained: the MBR-A (mean of all values), MBR-V (vessel mean) and MBR-T (tissue mean) in the ONH. With regard to eye diseases, no retinopathy of prematurity (ROP) was observed, and no severe systemic diseases requiring treatment were noted in the subjects. Pearson's correlation coefficients were used to determine the relationship between the MBR-A, -V, -T and postmenstrual age (days) and body weight (g). Postmenstrual age was significantly correlated with MBR-A (r = 0.64, p = 0.0007), MBR-V (r = 0.62, p = 0.0012) and MBR-T (r = 0.62, p = 0.0012). However, the body weight was not correlated with the MBR (MBR-A: r = 0.37, p = 0.07, MBR-V: r = 0.31, p = 0.14, MBR-T: r = 0.38, p = 0.06). Our results clarified that the values of ocular blood flow measured by LSFG correlate with the postmenstrual age of normal neonates.

New Marine Heat Flow measurements at the Costa Rica Rift, Panama Basin

NASA Astrophysics Data System (ADS)

Harris, R. N.; Kolandaivelu, K. P.; Gregory, E. P. M.; Alshafai, R.; Lowell, R. P.; Hobbs, R. W.

2016-12-01

We report new heat flow measurements collected along the southern flank of the Costa Rica ridge. This ridge flank has been the site of numerous seismic, heat flow, and ocean drilling experiments and has become an important type location for investigations of off-axis hydrothermal processes. These data were collected as part of an interdisciplinary NERC and NSF-funded collaboration entitled: Oceanographic and Seismic Characterization of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge (OSCAR), to better understand links between crustal evolution, hydrothermal heat loss and the impact of this heat loss and fluid mass discharge on deep ocean circulation. The heat flow measurements are collocated with a newly acquired high-resolution seismic profile collected using a GI-gun source to image the sedimentary and upper crustal section. The profile is tied to ODP Hole 504B and provides robust estimates of the sediment thickness as well as its internal structure. In total five heat flow stations consisting of 67 new heat flow measurements were made, spanning crustal ages between 1.3 and 5.4 Myr. The full spreading rate of 66 mm/yr gives rise to abyssal hill basement relief between 500 and 250 m. Sediment cover is relatively incomplete in this region and varies between 0 and 290 m. The majority of heat flow values fall below half-space cooling models indicating that significant amounts of heat are removed by hydrothermal circulation. Low heat flow values are observed in sediment ponds between abyssal hill relief and high values are generally associated with ridge-ward dipping faults bounding abyssal hills. These faults are likely high permeability pathways where heated fluids are discharging, providing an example where large-scale faulting and block rotation plays a major role in ventilated ridge flank fluid circulation. The heat flow fraction (qobs/qpred) varies between varies between 0.01 and 4.1 and has a mean of 0.3 indicating that on average 70% of the expected heat is advected. The mass flux associated with this heat advection is 5 x 10-6 kg/m2-s assuming temperature discharge on the ridge flank is 10° C above ambient.

Simultaneous measurements of temperature and density in air flows using UV laser spectroscopy

NASA Technical Reports Server (NTRS)

Fletcher, D. G.; Mckenzie, R. L.

1991-01-01

The simultaneous measurement of temperature and density using laser-induced fluorescence of oxygen in combination with Q-branch Raman scattering of nitrogen and oxygen is demonstrated in a low-speed air flow. The lowest density and temperature measured in the experiment correspond to the freestream values at Mach 5 in the Ames 3.5-Foot Hypersonic Wind Tunnel for stagnation conditions of 100 atm and 1000 K. The experimental results demonstrate the viability of the optical technique for measurements that support the study of compressible turbulence and the validation of numerical codes in supersonic and hypersonic wind tunnel flows.

A multi-time-step noise reduction method for measuring velocity statistics from particle tracking velocimetry

NASA Astrophysics Data System (ADS)

Machicoane, Nathanaël; López-Caballero, Miguel; Bourgoin, Mickael; Aliseda, Alberto; Volk, Romain

2017-10-01

We present a method to improve the accuracy of velocity measurements for fluid flow or particles immersed in it, based on a multi-time-step approach that allows for cancellation of noise in the velocity measurements. Improved velocity statistics, a critical element in turbulent flow measurements, can be computed from the combination of the velocity moments computed using standard particle tracking velocimetry (PTV) or particle image velocimetry (PIV) techniques for data sets that have been collected over different values of time intervals between images. This method produces Eulerian velocity fields and Lagrangian velocity statistics with much lower noise levels compared to standard PIV or PTV measurements, without the need of filtering and/or windowing. Particle displacement between two frames is computed for multiple different time-step values between frames in a canonical experiment of homogeneous isotropic turbulence. The second order velocity structure function of the flow is computed with the new method and compared to results from traditional measurement techniques in the literature. Increased accuracy is also demonstrated by comparing the dissipation rate of turbulent kinetic energy measured from this function against previously validated measurements.

Experimental performance of the regenerator for the Chrysler upgraded automotive gas turbine engine

NASA Technical Reports Server (NTRS)

Winter, J. M.; Nussle, R. C.

1982-01-01

Automobile gas turbine engine regenerator performance was studied in a regenerator test facility that provided a satisfactory simulation of the actual engine operating environment but with independent control of airflow and gas flow. Velocity and temperature distributions were measured immediately downstream of both the core high-pressure-side outlet and the core low-pressure-side outlet. For the original engine housing, the regenerator temperature effectiveness was 1 to 2 percent higher than the design value, and the heat transfer effectiveness was 2 to 4 percent lower than the design value over the range of test conditions simulating 50 to 100 percent of gas generator speed. Recalculating the design values to account for seal leakage decreased the design heat transfer effectiveness to values consistent with those measured herein. A baffle installed in the engine housing high-pressure-side inlet provided more uniform velocities out of the regenerator but did not improve the effectiveness. A housing designed to provide more uniform axial flow to the regenerator was also tested. Although temperature uniformity was improved, the effectiveness values were not improved. Neither did 50-percent flow blockage (90 degree segment) applied to the high-pressure-side inlet change the effectiveness significantly.

Performance of an electrochemical carbon monoxide monitor in the presence of anesthetic gases.

PubMed

Dunning, M; Woehlck, H J

1997-11-01

The passage of volatile anesthetic agents through accidentally dried CO2 absorbents in anesthesia circuits can result in the chemical breakdown of anesthetics with production of greater than 10000 ppm carbon monoxide (CO). This study was designed to evaluate a portable CO monitor in the presence of volatile anesthetic agents. Two portable CO monitors employing electrochemical sensors were tested to determine the effects of anesthetic agents, gas sample flow rates, and high CO concentrations on their electrochemical sensor. The portable CO monitors were exposed to gas mixtures of 0 to 500 ppm CO in either 70% nitrous oxide, 1 MAC concentrations of contemporary volatile anesthetics, or reacted isoflurane or desflurane (containing CO and CHF3) in oxygen. The CO measurements from the electrochemical sensors were compared to simultaneously obtained samples measured by gas chromatography (GC). Data were analyzed by linear regression. Overall correlation between the portable CO monitors and the GC resulted in an r2 value >0.98 for all anesthetic agents. Sequestered samples produced an exponential decay of measured CO with time, whereas stable measurements were maintained during continuous flow across the sensor. Increasing flow rates resulted in higher CO readings. Exposing the CO sensor to 3000 and 19000 ppm CO resulted in maximum reported concentrations of approximately 1250 ppm, with a prolonged recovery. Decrease in measured concentration of the sequestered samples suggests destruction of the sample by the sensor, whereas a diffusion limitation is suggested by the dependency of measured value upon flow. Any value over 500 ppm must be assumed to represent dangerous concentrations of CO because of the non-linear response of these monitors at very high CO concentrations. These portable electrochemical CO monitors are adequate to measure CO concentrations up to 500 ppm in the presence of typical clinical concentrations of anesthetics.

An automatic bolus injector for use in radiotracer studies of blood flow: design and evaluation.

PubMed

Snyder, R E; Overton, T R; Boisvert, D P; Petruk, K C

1976-12-01

An electromechanical device is described which automatically injects the radiotracer bolus used in the measurement of cerebral blood flow. It consists of two electronically controlled, solenoid operated syringes, one containing the radiotracer solution and the other heparinized saline. Results are presented which show that use of the automatic bolus injector in place of hand injection leads to an improvement in the precision of measured flow values. Additional advantages of the device are discussed.

Frontal lobe dysfunction in long-term cannabis users.

PubMed

Lundqvist, T; Jönsson, S; Warkentin, S

2001-01-01

This study examined the neurophysiological effects of cannabis. Cerebral blood flow (CBF) was measured in 12 long-term cannabis users shortly after cessation of cannabis use (mean 1.6 days). The findings showed significantly lower mean hemispheric blood flow values and significantly lower frontal values in the cannabis subjects compared to normal controls. The results suggest that the functional level of the frontal lobes is affected by long-term cannabis use.

Distribution of intrarenal blood flow consequent to left atrial balloon inflation.

PubMed

Passmore, J C; Stremel, R W; Hock, C E; Allen, R L; Bradford, W B

1985-01-01

The effects of inflation of a balloon within, and consequent distension of, the left atrium (LABI, left atrial balloon inflation) on total renal blood flow (RBF) and intrarenal blood flow distribution were measured and compared to values obtained from another group of dogs that were hemorrhaged (HEM) to the same level of hypotension as that produced by LABI, a mean systemic arterial pressure of 88 mm Hg. Kidney wt/kg, RBF/kg body wt, and urine flow were markedly reduced during the hemorrhage period in the HEM group when compared to values obtained during the experimental period for the LABI group. Data from the freeze-dissection (133Xe) analysis revealed that the percentage distribution of blood flow as renal outer cortical (OC) blood flow was less (26%) in the HEM group than in the LABI group (50%), this latter value being very similar to that of control dogs that experienced no hypotension (49%). LABI better maintains OC blood flow and urine flow when compared to HEM at the same systemic blood pressure, suggesting a role for cardiopulmonary receptors in reflex sympathetic control of renal blood flow distribution during hypotension.

Average properties of bidisperse bubbly flows

NASA Astrophysics Data System (ADS)

Serrano-García, J. C.; Mendez-Díaz, S.; Zenit, R.

2018-03-01

Experiments were performed in a vertical channel to study the properties of a bubbly flow composed of two distinct bubble size species. Bubbles were produced using a capillary bank with tubes with two distinct inner diameters; the flow through each capillary size was controlled such that the amount of large or small bubbles could be controlled. Using water and water-glycerin mixtures, a wide range of Reynolds and Weber number ranges were investigated. The gas volume fraction ranged between 0.5% and 6%. The measurements of the mean bubble velocity of each species and the liquid velocity variance were obtained and contrasted with the monodisperse flows with equivalent gas volume fractions. We found that the bidispersity can induce a reduction of the mean bubble velocity of the large species; for the small size species, the bubble velocity can be increased, decreased, or remain unaffected depending of the flow conditions. The liquid velocity variance of the bidisperse flows is, in general, bound by the values of the small and large monodisperse values; interestingly, in some cases, the liquid velocity fluctuations can be larger than either monodisperse case. A simple model for the liquid agitation for bidisperse flows is proposed, with good agreement with the experimental measurements.

Expiratory flow limitation relates to symptoms during COPD exacerbations requiring hospital admission.

PubMed

Jetmalani, Kanika; Timmins, Sophie; Brown, Nathan J; Diba, Chantale; Berend, Norbert; Salome, Cheryl M; Wen, Fu-Qiang; Chen, Peng; King, Gregory G; Farah, Claude S

2015-01-01

Expiratory flow limitation (EFL) is seen in some patients presenting with a COPD exacerbation; however, it is unclear how EFL relates to the clinical features of the exacerbation. We hypothesized that EFL when present contributes to symptoms and duration of recovery during a COPD exacerbation. Our aim was to compare changes in EFL with symptoms in subjects with and without flow-limited breathing admitted for a COPD exacerbation. A total of 29 subjects with COPD were recruited within 48 hours of admission to West China Hospital for an acute exacerbation. Daily measurements of post-bronchodilator spirometry, resistance, and reactance using the forced oscillation technique and symptom (Borg) scores until discharge were made. Flow-limited breathing was defined as the difference between inspiratory and expiratory respiratory system reactance (EFL index) greater than 2.8 cmH2O·s·L(-1). The physiological predictors of symptoms during recovery were determined by mixed-effect analysis. Nine subjects (31%) had flow-limited breathing on admission despite similar spirometry compared to subjects without flow-limited breathing. Spirometry and resistance measures did not change between enrolment and discharge. EFL index values improved in subjects with flow-limited breathing on admission, with resolution in four patients. In subjects with flow-limited breathing on admission, symptoms were related to inspiratory resistance and EFL index values. In subjects without flow-limited breathing, symptoms related to forced expiratory volume in 1 second/forced vital capacity. In the whole cohort, EFL index values at admission was related to duration of stay (Rs=0.4, P=0.03). The presence of flow-limited breathing as well as abnormal respiratory system mechanics contribute independently to symptoms during COPD exacerbations.

Incarcerated Inguinal Hernia Mesh Repair: Effect on Testicular Blood Flow and Sperm Autoimmunity.

PubMed

Krnić, Dragan; Družijanić, Nikica; Štula, Ivana; Čapkun, Vesna; Krnić, Duška

2016-05-05

BACKGROUND The aim of our study was to determine an influence of incarcerated inguinal hernia mesh repair on testicular circulation and to investigate consequent sperm autoimmunity as a possible reason for infertility. MATERIAL AND METHODS This prospective study was performed over a 3-year period, and 50 male patients were included; 25 of these patients underwent elective open mesh hernia repair (Group I). Group II consisted of 25 patients who had surgery for incarcerated inguinal hernia. Doppler ultrasound evaluation of the testicular blood flow and blood samplings for antisperm antibodies (ASA) was performed in all patients before the surgery, on the second day, and 5 months after. Main outcome ultrasound measures were resistive index (RI) and pulsative index (PI), as their values are inversely proportional to testicular blood flow. RESULTS In Group I, RI, and PI temporarily increased after surgery and then returned to basal values in the late postoperative period. Friedman analysis showed a significant difference in RI and PI for all measurements in Group II (p<0.05), with a significant decrease between the preoperative, early, and late postoperative periods. All final values were within reference range, including ASA, despite significant increase of ASA in the late postoperative period. CONCLUSIONS Although statistically significant differences in values of testicular flow parameters and immunologic sensitization in observed time, final values remained within the reference ranges in all patients. Our results suggest that the polypropylene mesh probably does not cause any clinically significant effect on testicular flow and immunologic response in both groups of patients.

Incarcerated Inguinal Hernia Mesh Repair: Effect on Testicular Blood Flow and Sperm Autoimmunity

PubMed Central

Krnić, Dragan; Družijanić, Nikica; Štula, Ivana; Čapkun, Vesna; Krnić, Duška

2016-01-01

Background The aim of our study was to determine an influence of incarcerated inguinal hernia mesh repair on testicular circulation and to investigate consequent sperm autoimmunity as a possible reason for infertility. Material/Methods This prospective study was performed over a 3-year period, and 50 male patients were included; 25 of these patients underwent elective open mesh hernia repair (Group I). Group II consisted of 25 patients who had surgery for incarcerated inguinal hernia. Doppler ultrasound evaluation of the testicular blood flow and blood samplings for antisperm antibodies (ASA) was performed in all patients before the surgery, on the second day, and 5 months after. Main outcome ultrasound measures were resistive index (RI) and pulsative index (PI), as their values are inversely proportional to testicular blood flow. Results In Group I, RI, and PI temporarily increased after surgery and then returned to basal values in the late postoperative period. Friedman analysis showed a significant difference in RI and PI for all measurements in Group II (p<0.05), with a significant decrease between the preoperative, early, and late postoperative periods. All final values were within reference range, including ASA, despite significant increase of ASA in the late postoperative period. Conclusions Although statistically significant differences in values of testicular flow parameters and immunologic sensitization in observed time, final values remained within the reference ranges in all patients. Our results suggest that the polypropylene mesh probably does not cause any clinically significant effect on testicular flow and immunologic response in both groups of patients. PMID:27149257

A spatial emergy model for Alachua County, Florida

NASA Astrophysics Data System (ADS)

Lambert, James David

A spatial model of the distribution of energy flows and storages in Alachua County, Florida, was created and used to analyze spatial patterns of energy transformation hierarchy in relation to spatial patterns of human settlement. Emergy, the available energy of one kind previously required directly or indirectly to make a product or service, was used as a measure of the quality of the different forms of energy flows and storages. Emergy provides a common unit of measure for comparing the productive contributions of natural processes with those of economic and social processes---it is an alternative to using money for measuring value. A geographic information system was used to create a spatial model and make maps that show the distribution and magnitude of different types of energy and emergy flows and storages occurring in one-hectare land units. Energy transformities were used to convert individual energy flows and storages into emergy units. Maps of transformities were created that reveal a clear spatial pattern of energy transformation hierarchy. The maps display patterns of widely-dispersed areas with lower transformity energy flows and storages, and smaller, centrally-located areas with higher transformities. Energy signature graphs and spatial unit transformities were used to characterize and compare the types and amounts of energy being consumed and stored according to land use classification, planning unit, and neighborhood categories. Emergy ratio maps and spatial unit ratios were created by dividing the values for specific emergy flows or storages by the values for other emergy flows or storages. Spatial context analysis was used to analyze the spatial distribution patterns of mean and maximum values for emergy flows and storages. The modeling method developed for this study is general and applicable to all types of landscapes and could be applied at any scale. An advantage of this general approach is that the results of other studies using this method will be directly comparable with the results of this study. The results and conclusions of this study reinforce the hypothesis that an urban landscape will develop a predictable spatial pattern that can be described in terms of a universal energy transformation hierarchy.

Concentration Dependence of VO2+ Crossover of Nafion for Vanadium Redox Flow Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lawton, Jamie; Jones, Amanda; Zawodzinski, Thomas A

2013-01-01

The VO2+ crossover, or permeability, through Nafion in a vanadium redox flow battery (VRFB) was monitored as a function of sulfuric acid concentration and VO2+ concentration. A vanadium rich solution was flowed on one side of the membrane through a flow field while symmetrically on the other side a blank or vanadium deficit solution was flowed. The blank solution was flowed through an electron paramagnetic resonance (EPR) cavity and the VO2+ concentration was determined from the intensity of the EPR signal. Concentration values were fit using a solution of Fick s law that allows for the effect of concentration changemore » on the vanadium rich side. The fits resulted in permeability values of VO2+ ions across the membrane. Viscosity measurements of many VO2+ and H2SO4 solutions were made at 30 60 C. These viscosity values were then used to determine the effect of the viscosity of the flowing solution on the permeability of the ion. 2013 The Electrochemical Society. [DOI: 10.1149/2.004306jes] All rights reserved.« less

Vortex dynamics and heat transfer behind self-oscillating inverted flags of various lengths in channel flow

NASA Astrophysics Data System (ADS)

Yu, Yuelong; Liu, Yingzheng; Chen, Yujia

2018-04-01

The influence of an inverted flag's length-to-channel-width ratio (C* = L/W) on its oscillating behavior in a channel flow and the resultant vortex dynamics and heat transfer are determined experimentally. Three systems with C* values of 0.125, 0.250, and 0.375 were chosen for comparison. The interaction of highly unsteady flow with the inverted flag is measured with time-resolved particle image velocimetry. Variations in the underlying flow physics are discussed in terms of the statistical flow quantities, flag displacement, phase-averaged flow field, and vortex dynamics. The results show that the increase in C* shifts the occurrence of the flapping regime at high dimensionless bending stiffness. With the flag in the flapping region, three distinct vortex dynamics—the von Kármán vortex street, the G mode, and the singular mode—are identified at C* values of 0.375, 0.250, and 0.125, respectively. Finally, the heat transfer enhancement from the self-oscillating inverted flag is measured to serve as complementary information to quantify the cause-and-effect relationship between vortex dynamics and wall heat transfer. The increase in C* strongly promotes wall heat removal because disruption of the boundary layer by the energetic vortices is substantially intensified. Among all systems, wall heat transfer removal is most efficient at the intermediate C* value of 0.250.

Detecting influential observations in nonlinear regression modeling of groundwater flow

USGS Publications Warehouse

Yager, Richard M.

1998-01-01

Nonlinear regression is used to estimate optimal parameter values in models of groundwater flow to ensure that differences between predicted and observed heads and flows do not result from nonoptimal parameter values. Parameter estimates can be affected, however, by observations that disproportionately influence the regression, such as outliers that exert undue leverage on the objective function. Certain statistics developed for linear regression can be used to detect influential observations in nonlinear regression if the models are approximately linear. This paper discusses the application of Cook's D, which measures the effect of omitting a single observation on a set of estimated parameter values, and the statistical parameter DFBETAS, which quantifies the influence of an observation on each parameter. The influence statistics were used to (1) identify the influential observations in the calibration of a three-dimensional, groundwater flow model of a fractured-rock aquifer through nonlinear regression, and (2) quantify the effect of omitting influential observations on the set of estimated parameter values. Comparison of the spatial distribution of Cook's D with plots of model sensitivity shows that influential observations correspond to areas where the model heads are most sensitive to certain parameters, and where predicted groundwater flow rates are largest. Five of the six discharge observations were identified as influential, indicating that reliable measurements of groundwater flow rates are valuable data in model calibration. DFBETAS are computed and examined for an alternative model of the aquifer system to identify a parameterization error in the model design that resulted in overestimation of the effect of anisotropy on horizontal hydraulic conductivity.

Turbofan aft duct suppressor study

NASA Technical Reports Server (NTRS)

Syed, A. A.; Motsinger, R. E.; Fiske, G. H.; Joshi, M. C.; Kraft, R. E.

1983-01-01

Suppressions due to acoustic treatment in the annular exhaust duct of a model fan were theoretically predicted and compared with measured suppressions. The predictions are based on the modal analysis of sound propagation in a straight annular flow duct with segmented treatment. Modal distributions of the fan noise source (fan-stator interaction only) were measured using in-duct modal probes. The flow profiles were also measured in the vicinity of the modal probes. The acoustic impedance of the single degree of freedom treatment was measured in the presence of grazing flow. The measured values of mode distribution of the fan noise source, the flow velocity profile and the acoustic impedance of the treatment in the duct were used as input to the prediction program. The predicted suppressions, under the assumption of uniform flow in the duct, compared well with the suppressions measured in the duct for all test conditions. The interaction modes generated by the rotor-stator interaction spanned a cut-off ratio range from nearly 1 to 7.

Heat-flow measurements at shot points along the 1978 Saudi Arabia seismic deep-refraction line; Part I, Results of the measurements

USGS Publications Warehouse

Gettings, M.E.; Showail, Abdullah

1982-01-01

Heat-flow measurements were made at five onland shot points of the 1978 Saudi Arabian seismic deep-refraction line, which sample major tectonic elements of the Arabian Shield along a profile from Ar Riyad to the Farasan Islands. Because of the pattern drilling at each shot point, several holes (60 m deep) could be logged for temperature at each site and thus allow a better estimate of the geothermal gradient. Each site was mapped and sampled in detail, and modal and. chemical analyses of representative specimens were made in the laboratory. Thermal conductivities were computed from the modal analyses and single-mineral conductivity data. The resulting heat-flow values, combined with published values for the Red Sea and coastal plain, indicate a three-level pattern, with a heat flow of about 4.5 heat-flow unit (HFU) over the Red Sea axial trough, about 3.0 HFU over the shelf and coastal plain, and an essentially constant 1.0 HFU over the Arabian Shield at points well away from the suture zone with the oceanic crust. At three sites where the rocks are granitic, gamma-ray spectrometry techniques were employed to estimate thorium, potassium, and uranium concentrations. The resulting plot of heat generation versus heat flow suggests that in the Arabian Shield the relationship between heat flow and heat production is not linear. More heat-flow data are essential to establish or reject this conclusion.

Planar Laser-Induced Iodine Fluorescence Measurements in Rarefied Hypersonic Flow

NASA Technical Reports Server (NTRS)

Cecil, Eric; McDaniel, James C.

2005-01-01

A planar laser-induced fluorescence (PLIF) technique is discussed and applied to measurement of time-averaged values of velocity and temperature in an I(sub 2)-seeded N(sub 2) hypersonic free jet facility. Using this technique, a low temperature, non-reacting, hypersonic flow over a simplified model of a reaction control system (RCS) was investigated. Data are presented of rarefied Mach 12 flow over a sharp leading edge flat plate at zero incidence, both with and without an interacting jet issuing from a nozzle built into the plate. The velocity profile in the boundary layer on the plate was resolved. The slip velocity along the plate, extrapolated from the velocity profile data, varied from nearly 100% down to 10% of the freestream value. These measurements are compared with results of a DSMC solution. The velocity variation along the centerline of a jet issuing from the plate was measured and found to match closely with the correlation of Ashkenas and Sherman. The velocity variation in the oblique shock terminating the jet was resolved sufficiently to measure the shock wave thickness.

10 CFR 431.264 - Uniform test method for the measurement of flow rate for commercial prerinse spray valves.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., the water consumption flow rate of commercial prerinse spray valves. (b) Testing and Calculations. The test procedure to determine the water consumption flow rate for prerinse spray valves, expressed in... the previous step. Round the final water consumption value to one decimal place as follows: (1) A...

Overland flow velocities on semiarid hillslopes 2471

USDA-ARS?s Scientific Manuscript database

A series of 188 rainfall plot simulations was conducted on grass, shrub, oak savanna, and juniper sites in Arizona and Nevada. A total of 897 flow velocity measurements was obtained on 3.6% to 39.6% slopes with values ranging from 0.007 m s-1 to 0.115 m s-1. The experimental data showed that flow ve...

Decreased femoral arterial flow during simulated microgravity in the rat

NASA Technical Reports Server (NTRS)

Roer, Robert D.; Dillaman, Richard M.

1994-01-01

To determine whether the blood supply to the hindlimbs of rats is altered by the tail-suspension model of weightlessness, rats were chronically instrumented for the measurement of femoral artery flow. Ultrasonic transit-time flow probes were implanted into 8-wk-old Wistar-Furth rats under ketamine-xylazine anesthesia, and, after 24 h of recovery, flow was measured in the normal ambulatory posture. Next, rats were suspended and flow was measured immediately and then daily over the next 4-7 days. Rats were subsequently returned to normal posture, and flow was monitored daily for 1-3 days. Mean arterial flow decreased immediately on the rats being suspensed and continued to decrease until a new steady state of approximately 60% of control values was attained at 5 days. On the rats returning to normal posture, flow increased to levels observed before suspension. Quantile-quantile plots of blood flow data revealed a decrease in flow during both systole and diastole. The observed decrease in hindlimb blood flow during suspension suggests a possible role in the etiology of muscular atrophy and bone loss in microgravity.

Higher harmonic flow coefficients of identified hadrons in Pb-Pb collisions at √{s_{NN}}=2.76 TeV

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Albuquerque, D. S. D.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; An, M.; Andrei, C.; Andrews, H. A.; Andronic, A.; Anguelov, V.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Balasubramanian, S.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Beltran, L. G. E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biro, G.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Bonora, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Cabala, J.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chauvin, A.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crkovska, J.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danisch, M. C.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; De, S.; De Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; De Souza, R. D.; Deisting, A.; Deloff, A.; Dénes, E.; Deplano, C.; Dhankher, P.; Di Bari, D.; Di Mauro, A.; Di Nezza, P.; Di Ruzza, B.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Endress, E.; Engel, H.; Epple, E.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Espagnon, B.; Estienne, M.; Esumi, S.; Eulisse, G.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Francisco, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gajdosova, K.; Gallio, M.; Galvan, C. D.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Garg, K.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Germain, M.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, A. S.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Grachov, O. A.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grosso, R.; Gruber, L.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Guzman, I. B.; Haake, R.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hamon, J. C.; Harris, J. W.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Hellbär, E.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Herrmann, F.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hippolyte, B.; Horak, D.; Hosokawa, R.; Hristov, P.; Hughes, C.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Inaba, M.; Incani, E.; Ippolitov, M.; Irfan, M.; Isakov, V.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacak, B.; Jacazio, N.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jahnke, C.; Jakubowska, M. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Khatun, A.; Kileng, B.; Kim, D. W.; Kim, D. J.; Kim, D.; Kim, H.; Kim, J. S.; Kim, J.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Ladron de Guevara, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lapidus, K.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, S.; Lehas, F.; Lehner, S.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; León Vargas, H.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Lupi, M.; Lutz, T. H.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Mao, Y.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzilli, M.; Mazzoni, M. A.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Mhlanga, S.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Mischke, A.; Mishra, A. N.; Mishra, T.; Miskowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Moreira De Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Münning, K.; Munzer, R. H.; Murakami, H.; Murray, S.; Musa, L.; Musinsky, J.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Navarro, S. R.; Nayak, K.; Nayak, R.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Negrao De Oliveira, R. A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Oleniacz, J.; Oliveira Da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Oravec, M.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, D.; Pagano, P.; Paić, G.; Pal, S. K.; Palni, P.; Pan, J.; Pandey, A. K.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Pei, H.; Peitzmann, T.; Peng, X.; Pereira Da Costa, H.; Peresunko, D.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pimentel, L. O. D. L.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Ploskon, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Poppenborg, H.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Ravasenga, I.; Read, K. F.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Saarinen, S.; Sadhu, S.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Sarkar, N.; Sarma, P.; Scapparone, E.; Scarlassara, F.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schmidt, M.; Schuchmann, S.; Schukraft, J.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Sheikh, A. I.; Shigaki, K.; Shou, Q.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singhal, V.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Sozzi, F.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Stachel, J.; Stan, I.; Stankus, P.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Sumowidagdo, S.; Swain, S.; Szabo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thakur, D.; Thomas, D.; Tieulent, R.; Tikhonov, A.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trombetta, G.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vala, M.; Valencia Palomo, L.; Van Der Maarel, J.; Van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vázquez Doce, O.; Vechernin, V.; Veen, A. M.; Velure, A.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Vickovic, L.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilk, G.; Wilkinson, J.; Willems, G. A.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yalcin, S.; Yang, P.; Yano, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yurchenko, V.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.

2016-09-01

The elliptic, triangular, quadrangular and pentagonal anisotropic flow coefficients for π±, K± and p+overline{p} in Pb-Pb collisions at √{s_{NN}}=2.76 TeV were measured with the ALICE detector at the Large Hadron Collider. The results were obtained with the Scalar Product method, correlating the identified hadrons with reference particles from a different pseudorapidity region. Effects not related to the common event symmetry planes (non-flow) were estimated using correlations in pp collisions and were subtracted from the measurement. The obtained flow coefficients exhibit a clear mass ordering for transverse momentum ( p T) values below ≈ 3 GeV/ c. In the intermediate p T region (3 < p T < 6 GeV/ c), particles group at an approximate level according to the number of constituent quarks, suggesting that coalescence might be the relevant particle production mechanism in this region. The results for p T < 3 GeV/ c are described fairly well by a hydrodynamical model (iEBE-VISHNU) that uses initial conditions generated by A Multi-Phase Transport model (AMPT) and describes the expansion of the fireball using a value of 0.08 for the ratio of shear viscosity to entropy density ( η/s), coupled to a hadronic cascade model (UrQMD). Finally, expectations from AMPT alone fail to quantitatively describe the measurements for all harmonics throughout the measured transverse momentum region. However, the comparison to the AMPT model highlights the importance of the late hadronic rescattering stage to the development of the observed mass ordering at low values of p T and of coalescence as a particle production mechanism for the particle type grouping at intermediate values of p T for all harmonics. [Figure not available: see fulltext.

Higher harmonic flow coefficients of identified hadrons in Pb-Pb collisions at $$\\sqrt{s_{\\mathrm{NN}}}=2.76 $$ TeV

DOE PAGES

Adam, J.; Adamová, D.; Aggarwal, M. M.; ...

2016-09-28

The elliptic, triangular, quadrangular and pentagonal anisotropic flow coefficients for π ± , K ± and p +more » $$\\bar{p}$$ in Pb-Pb collisions at √s NN=2.76 TeV were measured with the ALICE detector at the Large Hadron Collider. The results were obtained with the Scalar Product method, correlating the identified hadrons with reference particles from a different pseudorapidity region. Effects not related to the common event symmetry planes (non-flow) were estimated using correlations in pp collisions and were subtracted from the measurement. The obtained flow coefficients exhibit a clear mass ordering for transverse momentum (p T ) values below ≈ 3 GeV/c. In the intermediate p T region (3 < p T < 6 GeV/c), particles group at an approximate level according to the number of constituent quarks, suggesting that coalescence might be the relevant particle production mechanism in this region. The results for p T < 3 GeV/c are described fairly well by a hydrodynamical model (iEBE-VISHNU) that uses initial conditions generated by A Multi-Phase Transport model (AMPT) and describes the expansion of the fireball using a value of 0.08 for the ratio of shear viscosity to entropy density (η/s), coupled to a hadronic cascade model (UrQMD). Finally, expectations from AMPT alone fail to quantitatively describe the measurements for all harmonics throughout the measured transverse momentum region. However, the comparison to the AMPT model highlights the importance of the late hadronic rescattering stage to the development of the observed mass ordering at low values of p T and of coalescence as a particle production mechanism for the particle type grouping at intermediate values of p T for all harmonics.« less

An Investigation into Performance Modelling of a Small Gas Turbine Engine

DTIC Science & Technology

2012-10-01

b = Combustor part load constant f = Fuel to mass flow ratio or scale factor h = Enthalpy F = Force P = Pressure T = Temperature W = Mass flow...HP engine performance parameters[5,6] Parameter Condition (ISA, SLS) Value Thrust 108000 rpm 230 N Pressure Ratio 108000 rpm 4 Mass Flow Rate...system. The reasons for removing the electric starter were to ensure uniform flow through the bell- mouth for mass flow rate measurement, eliminate a

Features of separating turbulent boundary layers

NASA Technical Reports Server (NTRS)

Nagabushana, K. A.; Agarwal, Naval K.; Simpson, Roger L.

1988-01-01

In the present study of two strong adverse pressure gradient flows, mean flow and turbulence characteristics are measured, together with frequency spectra, using hot-wire and laser anemometry. In these separating flows, reattachment occurs over a shorter distance than separation. It is noted that the outer flow variables form a unique set of scaling parameters for streamwise power spectra in adverse pressure gradient flows. The inner flow scaling of Perry et al. (1985) for streamwise spectra does not hold in the backflow region unless the value of the downstream-upstream intermittency in the flow is unity.

Relationship between regional myocardial blood flow and thallium-201 distribution in the presence of coronary artery stenosis and dipyridamole-induced vasodilation.

PubMed Central

Mays, A E; Cobb, F R

1984-01-01

This study assesses the relationship between the distribution of thallium-201 and myocardial blood flow during coronary vasodilation induced by intravenous dipyridamole in canine models of partial and complete coronary artery stenosis. 10 dogs were chronically instrumented with catheters in the left atrium and aorta and with a balloon occluder and electromagnetic flow probe on the proximal left circumflex coronary artery. Regional myocardial blood flow was measured during control conditions with radioisotope-labeled microspheres, and the phasic reactive hyperemic response to a 20-s transient occlusion was then recorded. Dipyridamole was then infused intravenously until phasic coronary blood flow increased to match peak hyperemic values. The left circumflex coronary artery was either partially occluded to reduce phasic blood flow to control values (group 1) or it was completely occluded (group 2), and thallium-201 and a second microsphere label were injected. 5 min later, the animals were sacrificed, the left ventricle was sectioned into 1-2-g samples, and thallium-201 activity and regional myocardial blood flow were measured. Curvilinear regression analyses between thallium-201 localization and myocardial blood flow during dipyridamole infusion demonstrated a slightly better fit to a second- as compared with a first-order model, indicating a slight roll-off of thallium activity as myocardial blood flow increases. During the dipyridamole infusion, the increases in phasic blood flow, the distributions of regional myocardial blood flow, and the relationships between thallium-201 localization and regional blood flow were comparable to values previously observed in exercising dogs with similar occlusions. These data provide basic validation that supports the use of intravenous dipyridamole and thallium-201 as an alternative to exercise stress and thallium-201 for evaluating the effects of coronary occlusive lesions on the distribution of regional myocardial blood flow. PMID:6715540

Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Wenzhong; Yi, Ji; Chen, Siyu

Purpose: Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. Methods: The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (smallmore » ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. Results: In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as −0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31μl/min among four wild-type rats. The authors’ measured flow rates were consistent with results in the literature. Conclusions: By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length.« less

Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length

PubMed Central

Liu, Wenzhong; Yi, Ji; Chen, Siyu; Jiao, Shuliang; Zhang, Hao F.

2015-01-01

Purpose: Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. Methods: The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (small ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. Results: In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as −0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31μl/min among four wild-type rats. The authors’ measured flow rates were consistent with results in the literature. Conclusions: By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length. PMID:26328984

Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length.

PubMed

Liu, Wenzhong; Yi, Ji; Chen, Siyu; Jiao, Shuliang; Zhang, Hao F

2015-09-01

Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (small ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as -0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31 μl/min among four wild-type rats. The authors' measured flow rates were consistent with results in the literature. By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length.

The Streaming Potential Generated by Flow of Wet Steam in Capillary Tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marsden, S.S. Jr.; Tyran, Craig K.

1986-01-21

For a constant pressure differential, the flow of wet steam generated electric potentials which increased with time and did not reach equilibrium values. These potentials were found to increase to values greater than 100 volts. The reason for this kind of potential build-up behavior was the presence of tiny flowing water slugs which were interspersed with electrically nonconductive steam vapor slugs. The measured electric potential for wet steam increased with pressure differential, but the relationship was not linear. The increase in potential with pressure drop was attributed both to an increase in fluid flow rate and changes in the wetmore » steam quality.« less

Predictive value of reactive hyperemia for cardiovascular events in patients with peripheral arterial disease undergoing vascular surgery.

PubMed

Huang, Alex L; Silver, Annemarie E; Shvenke, Elena; Schopfer, David W; Jahangir, Eiman; Titas, Megan A; Shpilman, Alex; Menzoian, James O; Watkins, Michael T; Raffetto, Joseph D; Gibbons, Gary; Woodson, Jonathan; Shaw, Palma M; Dhadly, Mandeep; Eberhardt, Robert T; Keaney, John F; Gokce, Noyan; Vita, Joseph A

2007-10-01

Reactive hyperemia is the compensatory increase in blood flow that occurs after a period of tissue ischemia, and this response is blunted in patients with cardiovascular risk factors. The predictive value of reactive hyperemia for cardiovascular events in patients with atherosclerosis and the relative importance of reactive hyperemia compared with other measures of vascular function have not been previously studied. We prospectively measured reactive hyperemia and brachial artery flow-mediated dilation by ultrasound in 267 patients with peripheral arterial disease referred for vascular surgery (age 66+/-11 years, 26% female). Median follow-up was 309 days (range 1 to 730 days). Fifty patients (19%) had an event, including cardiac death (15), myocardial infarction (18), unstable angina (8), congestive heart failure (6), and nonhemorrhagic stroke (3). Patients with an event were older and had lower hyperemic flow velocity (75+/-39 versus 95+/-50 cm/s, P=0.009). Patients with an event also had lower flow-mediated dilation (4.5+/-3.0 versus 6.9+/-4.6%, P<0.001), and when these 2 measures of vascular function were included in the same Cox proportional hazards model, lower hyperemic flow (OR 2.7, 95% CI 1.2 to 5.9, P=0.018) and lower flow-mediated dilation (OR 4.2, 95% CI: 1.8 to 9.8, P=0.001) both predicted cardiovascular events while adjusting for other risk factors. Thus, lower reactive hyperemia is associated with increased cardiovascular risk in patients with peripheral arterial disease. Furthermore, flow-mediated dilation and reactive hyperemia incrementally relate to cardiovascular risk, although impaired flow-mediated dilation was the stronger predictor in this population. These findings further support the clinical relevance of vascular function measured in the microvasculature and conduit arteries in the upper extremity.

Heat Flow and Hydrothermal Circulation of the Lucky Strike Segment, Mid Atlantic Ridge

NASA Astrophysics Data System (ADS)

Bonneville, A.; Escartin, J.; Lucazeau, F.; Cannat, M.; Gouze, P.; von Herzen, R. P.; Adam, C.; Le Bars, M.; Monoury, E.; Vidal, V.

2003-12-01

In June 2003, expedition Luckyflux aboard the R/V Poseidon conducted a heat flow survey of a zone centred on the Lucky Strike segment of the Mid Atlantic ridge south of the Azores between ˜35° N and 39° N. Using a 5 m-long lance with 7 outrigger thermal probes, about 150 successful thermal gradient measurements were obtained, 140 of these with in-situ thermal conductivity. Measurements were made at ˜1 mile intervals along several profiles, where adequately sedimented sites were identified using 6-channel and 3.5 kHz seismic data from the previous Sudazores'98 cruise. We conducted heat flow measurements in two areas: a near axis region within the V-shaped ridge of overthickened crust that emanated from the Azores hotspot between ˜14 and 4 Ma, and an off-axis region East of the V-shaped ridge. The off-axis region is characterized by an homogeneous sediment cover, 300-400 m thick, and crustal ages varying between ˜6 and >10 Ma. Long wavelength (tens of km) low heat flow anomalies can be identified but the mean of 160 mWm-2 is comparable to the conductive heat flow expected for a crust of that age. Along two 80-km profiles perpendicular to the ridge, we observed coherent but different patterns. On the first profile, low heat flow values of 20-50 mWm-2 are observed at the base of the V-shaped ridge. These values are 100 mWm-2 below the profile average, showing that hydrothermal circulations can also affect oceanic crust beneath a thick and relatively impermeable sediment cover. On the other profile, heat flow generally decreases from west to east. On both profiles, higher than average values of heat flow are also present, associated on one of them with a nearly outcropping basement elevation. These contrasting overall heat flow patterns in similar geological context indicate that the likely pattern of hydrothermal circulations is mainly 3D, and not driven only by the presence of basement outcrops. In the near-axis region, where the tectonic structure is more complicated and the sediment cover heterogeneous, heat flow data show no clear spatial variation and their mean value, 60 to 90 mWm-2, is systematically lower than theoretical conductive values for young seafloor. These heat flow differences will be used to estimate the importance of advection in the heat budget. This characterization of the regional thermal state around a slow-spreading segment will provide the basis for future long-term studies on the structure, thermal evolution and the hydrothermal systems within the MOMAR (MOnitoring the Mid Atlantic Ridge) project.

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

NASA Astrophysics Data System (ADS)

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

2016-01-01

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

Ultrasonic assessment of hepatic blood flow as a marker of mouse hepatocarcinoma.

PubMed

Bonnin, Philippe; Villemain, Aude; Vincent, François; Debbabi, Haythem; Silvestre, Jean Sébastien; Contreres, Jean Olivier; Levy, Bernard I; Tobelem, Gérard; Dupuy, Evelyne

2007-04-01

Two-dimensional color-coded pulsed Doppler ultrasonography (US) with a 12-MHz linear transducer was used to follow tumor growth and neoangiogenesis development in 12 transgenic mice developing a whole liver hepatocellular carcinoma (HCC) induced by the expression of SV40-T antigen. In this model, male mice developed HCC at various temporal and histologic stages (hyperplastic, four-eight wk; nodular, 12 wk; diffuse carcinoma, 16-20 wk), whereas female mice remained tumor free. Seven age-matched tumor-free mice were used as controls. Liver volume was calculated from B-mode images of the abdomen. Blood flow waveforms were recorded from the hepatic tumor-feeding artery upstream from the tumor vessels, allowing quantitative blood flow velocity measurements. Measurements were performed every four weeks from four to 20 weeks. As early as the hyperplastic stage (eight weeks), liver volume was increased by 2.7-fold, hepatic artery peak-systolic blood flow velocities (BFV) by 1.5-fold, end-diastolic BFV by 1.6-fold and mean BFV by 2.0-fold compared with control values (p < 0.001). Differences increased until 20 weeks and peak-systolic reached 90 +/- 6, end-diastolic 54 +/- 5 and mean BFV 48 +/- 5 cm s(-1). Successive measurements of BFV were reproducible and intraobserver repeatability coefficient values were <3 cm s(-1). In contrast, mesenteric artery BFV, which did not supply tumor region, did not show any significant difference with respect to control values. Thus, an increase in BFV constitutes a functional evaluation of tumor vascularity. In preclinical studies in small animals, measurements of liver volume and blood flow velocities in hepatic tumor-feeding artery provide a useful, reproducible, noninvasive, easy-to-repeat tool to monitor tumor growth and neoangiogenesis in hepatocellular carcinoma in mice.

Estimating maximum instantaneous distortion from inlet total pressure rms and PSD measurements. [Root Mean Square and Power Spectral Density methods

NASA Technical Reports Server (NTRS)

Melick, H. C., Jr.; Ybarra, A. H.; Bencze, D. P.

1975-01-01

An inexpensive method is developed to determine the extreme values of instantaneous inlet distortion. This method also provides insight into the basic mechanics of unsteady inlet flow and the associated engine reaction. The analysis is based on fundamental fluid dynamics and statistical methods to provide an understanding of the turbulent inlet flow and quantitatively relate the rms level and power spectral density (PSD) function of the measured time variant total pressure fluctuations to the strength and size of the low pressure regions. The most probable extreme value of the instantaneous distortion is then synthesized from this information in conjunction with the steady state distortion. Results of the analysis show the extreme values to be dependent upon the steady state distortion, the measured turbulence rms level and PSD function, the time on point, and the engine response characteristics. Analytical projections of instantaneous distortion are presented and compared with data obtained by a conventional, highly time correlated, 40 probe instantaneous pressure measurement system.

Simulated Microgravity Increases Cutaneous Blood Flow in the Head and Leg of Humans

NASA Technical Reports Server (NTRS)

Stout, M. Shannon; Watenpaugh, Donald E.; Breit, Gregory A.; Hargens, Alan R.

1995-01-01

The cutaneous microcirculation vasodilates during acute 6 degree head-down tilt (HDT, simulated microgravity) relative to upright conditions, more in the lower body than in the upper body. Cutaneous microvascular blood flow was measured with laser-Doppler flowmetry at the leg (over the distal tibia) and cheek (over the zygomatic arch) of eight healthy men before, during, and after 24 h of HDT. Results were calculated as a percentage of baseline value (100% measured during pre-tilt upright sitting). Cutaneous blood flow in the cheek increased significantly to 165 +/- 37% (mean +/- SE, p less than 0.05) at 9-12 h HDT, then returned to near baseline values by 24 h HDT (114 +/- 29%, NSD), despite increased local arterial pressure. Microvascular flow in the leg remained significantly elevated above baseline througout 24 h HDT (427 +/- 85% at 3 h HDT and 215 +/- 142% at 24 h HDT, p less than 0.05). During the 6-h upright sitting recovery period, cheek and leg blood flow levels returned to near pre-tilt baseline values. Because hydrostatic effects of HDT increase local arterial pressure at the carotid sinus, baroreflex-mediated withdrawal of sympathetic tone probably contributed to increased microvascular flows at the head and leg during HDT. In the leg baroreflex effects combined with minimal stimulation of local veno-arteriolar and myogenic autoregulatory vasoconstriction to elicit relatively larger and more sustained increases in cutaneous flow during HDT. In the cheek, delayed myogenic vasoconstriction and/or hurmonal effects apparently compensated for flow elevation by 24 h of HDT. Therefore, localized vascular adaptations to gravity probably explain differences in acclimation of lower and upper body blood flow to HDT and actual microgravity.

Feather roughness reduces flow separation during low Reynolds number glides of swifts.

PubMed

van Bokhorst, Evelien; de Kat, Roeland; Elsinga, Gerrit E; Lentink, David

2015-10-01

Swifts are aerodynamically sophisticated birds with a small arm and large hand wing that provides them with exquisite control over their glide performance. However, their hand wings have a seemingly unsophisticated surface roughness that is poised to disturb flow. This roughness of about 2% chord length is formed by the valleys and ridges of overlapping primary feathers with thick protruding rachides, which make the wing stiffer. An earlier flow study of laminar-turbulent boundary layer transition over prepared swift wings suggested that swifts can attain laminar flow at a low angle of attack. In contrast, aerodynamic design theory suggests that airfoils must be extremely smooth to attain such laminar flow. In hummingbirds, which have similarly rough wings, flow measurements on a 3D printed model suggest that the flow separates at the leading edge and becomes turbulent well above the rachis bumps in a detached shear layer. The aerodynamic function of wing roughness in small birds is, therefore, not fully understood. Here, we performed particle image velocimetry and force measurements to compare smooth versus rough 3D-printed models of the swift hand wing. The high-resolution boundary layer measurements show that the flow over rough wings is indeed laminar at a low angle of attack and a low Reynolds number, but becomes turbulent at higher values. In contrast, the boundary layer over the smooth wing forms open laminar separation bubbles that extend beyond the trailing edge. The boundary layer dynamics of the smooth surface varies non-linearly as a function of angle of attack and Reynolds number, whereas the rough surface boasts more consistent turbulent boundary layer dynamics. Comparison of the corresponding drag values, lift values and glide ratios suggests, however, that glide performance is equivalent. The increased structural performance, boundary layer robustness and equivalent aerodynamic performance of rough wings might have provided small (proto) birds with an evolutionary window to high glide performance. © 2015. Published by The Company of Biologists Ltd.

The viscosity of pāhoehoe lava: In situ syn-eruptive measurements from Kilauea, Hawaii

NASA Astrophysics Data System (ADS)

Chevrel, Magdalena Oryaëlle; Harris, Andrew J. L.; James, Mike R.; Calabrò, Laura; Gurioli, Lucia; Pinkerton, Harry

2018-07-01

Viscosity is one of the most important physical properties controlling lava flow dynamics. Usually, viscosity is measured in the laboratory where key parameters can be controlled but can never reproduce the natural environment and original state of the lava in terms of crystal and bubble contents, dissolved volatiles, and oxygen fugacity. The most promising approach for quantifying the rheology of molten lava in its natural state is therefore to carry out direct field measurements by inserting a viscometer into the lava while it is flowing. Such in-situ syn-eruptive viscosity measurements are notoriously difficult to perform due to the lack of appropriate instrumentation and the difficulty of working on or near an active lava flow. In the field, rotational viscometer measurements are of particular value as they have the potential to measure the properties of the flow interior rather than an integration of the viscosity of the viscoelastic crust + flow interior. To our knowledge only one field rotational viscometer is available, but logistical constraints have meant that it has not been used for 20 yr. Here, we describe new viscosity measurements made using the refurbished version of this custom-built rotational viscometer, as performed on active pāhoehoe lobes from the 61G lava flow of Kilauea's Pu'u 'Ō'ō eruption in 2016. We successfully measured a viscosity of ∼380 Pa s at strain-rates between 1.6 and 5 s-1 and at 1144 °C. Additionally, synchronous lava sampling allowed us to provide detailed textural and chemical characterization of quenched samples. Application of current physico-chemical models based on this characterization (16 ± 4 vol.% crystals; 50 ± 6 vol.% vesicles), gave viscosity estimates that were approximately compatible with the measured values, highlighting the sensitivity of model-based viscosity estimates on the effect of deformable bubbles. Our measurements also agree on the range of viscosities in comparison to previous field experiments on Hawaiian lavas. Conversely, direct comparison with sub-liquidus rheological laboratory measurements on natural lavas was unsuccessful because recreating field conditions (in particular volatile and bubble content) is so far inaccessible in the laboratory. Our work shows the value of field rotational viscometry fully-integrated with sample characterization to quantify three-phase lava viscosity. Finally, this work suggests the need for the development of a more versatile instrument capable of recording precise measurements at low torque and low strain rate, and with synchronous temperature measurements.

Wall-wake velocity profile for compressible non-adiabatic flows

NASA Technical Reports Server (NTRS)

Sun, C. C.; Childs, M. E.

1975-01-01

A form of the wall-wake profile, which is applicable to flows with heat transfer, and for which a variation in y = O at y = delta, was suggested. The modified profile, which takes into account the effect of turbulent Prandtl number, was found to provide a good representation of experimental data for a wide range numbers and heat transfer. The Cf values which are determined by a least squares fit of the profile to the data agree well with values which were measured by the floating element technique. In addition, the values of delta determined by the fit correspond more closely to the outer edge of the viscous flow region than those obtained with earlier versions of the wall-wake profile.

Ground-Water Flow in the Vicinity of the Ho-Chunk Nation Communities of Indian Mission and Sand Pillow, Jackson County, Wisconsin

USGS Publications Warehouse

Dunning, Charles P.; Mueller, Gregory D.; Juckem, Paul F.

2008-01-01

An analytic element ground-water-flow model was constructed to help understand the ground-water-flow system in the vicinity of the Ho-Chunk Nation communities of Indian Mission and Sand Pillow in Jackson County, Wisconsin. Data from interpretive reports, well-drillers' construction reports, and an exploratory augering program in 2003 indicate that sand and gravel of varying thickness (0-150 feet[ft]) and porous sandstone make up a composite aquifer that overlies Precambrian crystalline rock. The geometric mean values for horizontal hydraulic conductivity were estimated from specific-capacity data to be 61.3 feet per day (ft/d) for sand and gravel, 6.6 ft/d for sandstone, and 12.0 ft/d for the composite aquifer. A ground-water flow model was constructed, the near field of which encompassed the Levis and Morrison Creeks Watershed. The flow model was coupled to the parameter-estimation program UCODE to obtain a best fit between simulated and measured values of ground-water levels and estimated Q50 flow duration (base flow). Calibration of the model with UCODE provided a ground-water recharge rate of 9 inches per year and a horizontal hydraulic conductivity of 13 ft/d for the composite aquifer. Using these calibrated parameter values, simulated heads from the model were on average within 5 ft of the measured water levels. In addition, these parameter values provided an acceptable base-flow calibration for Hay, Dickey, and Levis Creeks; the calibration was particularly close for Levis Creek, which was the most frequently measured stream in the study area. The calibrated model was used to simulate ground-water levels and to determine the direction of ground-water flow in the vicinity of Indian Mission and Sand Pillow communities. Backward particle tracking was conducted for Sand Pillow production wells under two pumping simulations to determine their 20-year contributing areas. In the first simulation, new production wells 6, 7, and 8 were each pumped at 50 gallons per minute (gal/min). In the second simulation, new production wells 6, 7, and 8 and existing production well 5 were each pumped at 50 gal/min. The second simulation demonstrated interference between the existing production well 5 and the new production wells when all were pumping at 50 gal/min.

Heat flow and heat generation in greenstone belts

NASA Technical Reports Server (NTRS)

Drury, M. J.

1986-01-01

Heat flow has been measured in Precambrian shields in both greenstone belts and crystalline terrains. Values are generally low, reflecting the great age and tectonic stability of the shields; they range typically between 30 and 50 mW/sq m, although extreme values of 18 and 79 mW/sq m have been reported. For large areas of the Earth's surface that are assumed to have been subjected to a common thermotectonic event, plots of heat flow against heat generation appear to be linear, although there may be considerable scatter in the data. The relationship is expressed as: Q = Q sub o + D A sub o in which Q is the observed heat flow, A sub o is the measured heat generation at the surface, Q sub o is the reduced heat flow from the lower crust and mantle, and D, which has the dimension of length, represents a scale depth for the distribution of radiogenic elements. Most authors have not used data from greenstone belts in attempting to define the relationship within shields, considering them unrepresentative and preferring to use data from relatively homogeneous crystalline rocks. A discussion follows.

Simultaneous blood flow and blood oxygenation measurements using a combination of diffuse speckle contrast analysis and near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Seong, Myeongsu; Phillips, Zephaniah; Mai, Phuong Minh; Yeo, Chaebeom; Song, Cheol; Lee, Kijoon; Kim, Jae Gwan

2016-02-01

A combined diffuse speckle contrast analysis (DSCA)-near-infrared spectroscopy (NIRS) system is proposed to simultaneously measure qualitative blood flow and blood oxygenation changes in human tissue. The system employs an optical switch to alternate two laser sources at two different wavelengths and a CCD camera to capture the speckle image. Therefore, an optical density can be measured from two wavelengths for NIRS measurements and a speckle contrast can be calculated for DSCA measurements. In order to validate the system, a flow phantom test and an arm occlusion protocol for arterial and venous occlusion were performed. Shorter exposure times (<1 ms) show a higher drop (between 50% and 66%) and recovery of 1/KS2 values after occlusion (approximately 150%), but longer exposure time (3 ms) shows more consistent hemodynamic changes. For four subjects, the 1/KS2 values dropped to an average of 82.1±4.0% during the occlusion period and the average recovery of 1/KS2 values after occlusion was 109.1±0.8%. There was also an approximately equivalent amplitude change in oxyhemoglobin (OHb) and deoxyhemoglobin (RHb) during arterial occlusion (max RHb=0.0085±0.0024 mM/DPF, min OHb=-0.0057±0.0044 mM/DPF). The sensitivity of the system makes it a suitable modality to observe qualitative hemodynamic trends during induced physiological changes.

In vitro calibration of a system for measurement of in vivo convective heat transfer coefficient in animals

PubMed Central

Tangwongsan, Chanchana; Chachati, Louay; Webster, John G; Farrell, Patrick V

2006-01-01

Background We need a sensor to measure the convective heat transfer coefficient during ablation of the heart or liver. Methods We built a minimally invasive instrument to measure the in vivo convective heat transfer coefficient, h in animals, using a Wheatstone-bridge circuit, similar to a hot-wire anemometer circuit. One arm is connected to a steerable catheter sensor whose tip is a 1.9 mm × 3.2 mm thin film resistive temperature detector (RTD) sensor. We used a circulation system to simulate different flow rates at 39°C for in vitro experiments using distilled water, tap water and saline. We heated the sensor approximately 5°C above the fluid temperature. We measured the power consumed by the sensor and the resistance of the sensor during the experiments and analyzed these data to determine the value of the convective heat transfer coefficient at various flow rates. Results From 0 to 5 L/min, experimental values of h in W/(m2·K) were for distilled water 5100 to 13000, for tap water 5500 to 12300, and for saline 5400 to 13600. Theoretical values were 1900 to 10700. Conclusion We believe this system is the smallest, most accurate method of minimally invasive measurement of in vivo h in animals and provides the least disturbance of flow. PMID:17067386

40 CFR 1065.202 - Data updating, recording, and control.

Code of Federal Regulations, 2010 CFR

2010-07-01

... means. § 1065.514, § 1065.530 Steady-state and ramped-modal duty cycle reference and feedback speeds and... mean value per test interval. § 1065.530, § 1065.545 Diluted exhaust flow rate from a CVS with a heat exchanger upstream of the flow measurement N/A 1 Hz. § 1065.530, § 1065.545 Diluted exhaust flow rate from a...

Study on Gas-liquid Falling Film Flow in Internal Heat Integrated Distillation Column

NASA Astrophysics Data System (ADS)

Liu, Chong

2017-10-01

Gas-liquid internally heat integrated distillation column falling film flow with nonlinear characteristics, study on gas liquid falling film flow regulation control law, can reduce emissions of the distillation column, and it can improve the quality of products. According to the distribution of gas-liquid mass balance internally heat integrated distillation column independent region, distribution model of heat transfer coefficient of building internal heat integrated distillation tower is obtained liquid distillation falling film flow in the saturated vapour pressure of liquid water balance, using heat transfer equation and energy equation to balance the relationship between the circulating iterative gas-liquid falling film flow area, flow parameter information, at a given temperature, pressure conditions, gas-liquid flow falling film theory makes the optimal parameters to achieve the best fitting value with the measured values. The results show that the geometric gas-liquid internally heat integrated distillation column falling film flow heat exchange area and import column thermostat, the average temperature has significant. The positive correlation between the heat exchanger tube entrance due to temperature difference between inside and outside, the heat flux is larger, with the increase of internal heat integrated distillation column temperature, the slope decreases its temperature rise, which accurately describes the internal gas-liquid heat integrated distillation tower falling film flow regularity, take appropriate measures to promote the enhancement of heat transfer. It can enhance the overall efficiency of the heat exchanger.

Theoretical analysis of stack gas emission velocity measurement by optical scintillation

NASA Astrophysics Data System (ADS)

Yang, Yang; Dong, Feng-Zhong; Ni, Zhi-Bo; Pang, Tao; Zeng, Zong-Yong; Wu, Bian; Zhang, Zhi-Rong

2014-04-01

Theoretical analysis for an online measurement of the stack gas flow velocity based on the optical scintillation method with a structure of two parallel optical paths is performed. The causes of optical scintillation in a stack are first introduced. Then, the principle of flow velocity measurement and its mathematical expression based on cross correlation of the optical scintillation are presented. The field test results show that the flow velocity measured by the proposed technique in this article is consistent with the value tested by the Pitot tube. It verifies the effectiveness of this method. Finally, by use of the structure function of logarithmic light intensity fluctuations, the theoretical explanation of optical scintillation spectral characteristic in low frequency is given. The analysis of the optical scintillation spectrum provides the basis for the measurement of the stack gas flow velocity and particle concentration simultaneously.

Relationship of 133Xe cerebral blood flow to middle cerebral arterial flow velocity in men at rest

NASA Technical Reports Server (NTRS)

Clark, J. M.; Skolnick, B. E.; Gelfand, R.; Farber, R. E.; Stierheim, M.; Stevens, W. C.; Beck, G. Jr; Lambertsen, C. J.

1996-01-01

Cerebral blood flow (CBF) was measured by 133Xe clearance simultaneously with the velocity of blood flow through the left middle cerebral artery (MCA) over a wide range of arterial PCO2 in eight normal men. Average arterial PCO2, which was varied by giving 4% and 6% CO2 in O2 and by controlled hyperventilation on O2, ranged from 25.3 to 49.9 mm Hg. Corresponding average values of global CBF15 were 27.2 and 65.0 ml 100 g min-1, respectively, whereas MCA blood-flow velocity ranged from 42.8 to 94.2 cm/s. The relationship of CBF to MCA blood-flow velocity over the imposed range of arterial PCO2 was described analytically by a parabola with the equation: CBF = 22.8 - 0.17 x velocity + 0.006 x velocity2 The observed data indicate that MCA blood-flow velocity is a useful index of CBF response to change in arterial PCO2 during O2 breathing at rest. With respect to baseline values measured while breathing 100% O2 spontaneously, percent changes in velocity were significantly smaller than corresponding percent changes in CBF at increased levels of arterial PCO2 and larger than CBF changes at the lower arterial PCO2. These observed relative changes are consistent with MCA vasodilation at the site of measurement during exposure to progressive hypercapnia and also during extreme hyperventilation hypocapnia.

Use of sap flow measurements to validate stomatal functions for mature beech (Fagus sylvatica) in view of ozone uptake calculations.

PubMed

Braun, Sabine; Schindler, Christian; Leuzinger, Sebastian

2010-09-01

For a quantitative estimate of the ozone effect on vegetation reliable models for ozone uptake through the stomata are needed. Because of the analogy of ozone uptake and transpiration it is possible to utilize measurements of water loss such as sap flow for quantification of ozone uptake. This technique was applied in three beech (Fagus sylvatica) stands in Switzerland. A canopy conductance was calculated from sap flow velocity and normalized to values between 0 and 1. It represents mainly stomatal conductance as the boundary layer resistance in forests is usually small. Based on this relative conductance, stomatal functions to describe the dependence on light, temperature, vapour pressure deficit and soil moisture were derived using multivariate nonlinear regression. These functions were validated by comparison with conductance values directly estimated from sap flow. The results corroborate the current flux parameterization for beech used in the DO3SE model. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Film cooling: case of double rows of staggered jets.

PubMed

Dorignac, E; Vullierme, J J; Noirault, P; Foucault, E; Bousgarbiès, J L

2001-05-01

An experimental investigation of film cooling of a wall in a case of double rows of staggered hot jets (65 degrees C) in an ambient air flow. The wall is heated at a temperature value between the one of the jets and the one of the main flow. Experiments have been carried out for different injection rates, the main flow velocity is maintained at 32 m/s. Association of the measures of temperature profiles by cold wire and the measures of wall temperature by infrared thermography allows us to describe the behaviour of the flows and to propose the best injection which assures a good cooling of the plate.

Cerebral oxygenation in the beach chair position for shoulder surgery in regional anesthesia: impact on cerebral blood flow and neurobehavioral outcome.

PubMed

Aguirre, José A; Märzendorfer, Olivia; Brada, Muriel; Saporito, Andrea; Borgeat, Alain; Bühler, Philipp

2016-12-01

Beach chair position is considered a potential risk factor for central neurological events particularly if combined with low blood pressure. The aim of this study was to assess the impact of regional anesthesia on cerebral blood flow and neurobehavioral outcome. This is a prospective, assessor-blinded observational study evaluating patients in the beach chair position undergoing shoulder surgery under regional anesthesia. University hospital operating room. Forty patients with American Society of Anesthesiologists classes I-II physical status scheduled for elective shoulder surgery. Cerebral saturation and blood flow of the middle cerebral artery were measured prior to anesthesia and continued after beach chair positioning until discharge to the postanesthesia care unit. The anesthesiologist was blinded for these values. Controlled hypotension with systolic blood pressure≤100mm Hg was maintained during surgery. Neurobehavioral tests and values of regional cerebral saturation, bispectral index, the mean maximal blood flow of the middle cerebral artery, and invasive blood pressure were measured prior to regional anesthesia, and measurements were repeated after placement of the patient on the beach chair position and every 20 minutes thereafter until discharge to postanesthesia care unit. The neurobehavioral tests were repeated the day after surgery. The incidence of cerebral desaturation events was 5%. All patients had a significant blood pressure drop 5 minutes after beach chair positioning, measured at the heart as well as the acoustic meatus levels, when compared with baseline values (P<.05). There was no decrease in either the regional cerebral saturation (P=.136) or the maximal blood flow of the middle cerebral artery (P=.212) at the same time points. Some neurocognitive tests showed an impairment 24 hours after surgery (P<.001 for 2 of 3 tests). Beach chair position in patients undergoing regional anesthesia for shoulder surgery had no major impact on cerebral blood flow and cerebral oxygenation. However, some impact on neurobehavioral outcome 24 hours after surgery was observed. Copyright © 2016 Elsevier Inc. All rights reserved.

Lower limb sympathectomy assessed by laser Doppler blood flow and transcutaneous oxygen measurements.

PubMed

Lantsberg, L; Goldman, M

1990-01-01

In a retrospective study of critical ischaemia of the lower limb, sympathectomy appeared to be of value in the majority of patients. We therefore assessed sympathectomy by measuring skin blood flow before and after the procedure using laser Doppler flowmetry (LDF) and transcutaneous oxygen tension (TCpO2) techniques. Twenty patients underwent chemical sympathectomy and there was one surgical procedure. Measurements were performed before and 1 week after sympathectomy below the knee and on the forefoot. Symptomatic improvement occurred in 20 of 21 patients. This study demonstrates that skin blood flow in the leg and foot is improved by sympathectomy and confirms objectively our clinical impression.

Groundwater flow and potential effects on evaporite dissolution in the Paradox Basin, SE Utah

NASA Astrophysics Data System (ADS)

Reitman, N.; Ge, S.; Mueller, K. J.

2012-12-01

A hydrogeologic study was conducted in the portion of the Paradox Basin south of the Needles District of Canyonlands National Park, Utah. Geology of the study area comprises fractured and faulted Paleozoic sandstone, limestone, and shale, which are underlain by evaporite cycles of the Paradox Formation. The evaporite deposits deform and dissolve when they come in contact with groundwater, generating land subsidence, saline groundwater, and salt input to the Colorado River. Active faults in the region slip at a rate of approximately 2 mm/year, likely due to evaporite dissolution. The objective of this study is to better understand groundwater flow and solute transport dynamics and to help determine the rate and timing of subsurface salt dissolution, which is an important control on the salt tectonics in the region. Study methods include hydrologic fieldwork, laboratory tests, and numerical modeling. No groundwater wells exist in the study area. Water samples from springs and seeps were collected throughout the study area. Analysis of total dissolved solids (TDS), stable oxygen (δ18O) and deuterium (δD) isotopes, spring and seep locations, and prior data are used to gain a preliminary understanding of the shallow groundwater flow in the region. Stable isotope ratios of oxygen (18O/16O) and deuterium (D/H) are used to constrain the source of spring water. Measured δ values are compared to predicted δ values for precipitation from WaterIsotopes.org for each sample site. Measured isotopic values range from -14.9 ‰ to -10.7 ‰ for δ18O and -108 ‰ to -78 ‰ for δD. The majority of samples from above 2000 m match predicted isotopic values for precipitation. Most samples taken below 2000 m are lighter than predicted isotopic values for precipitation. The TDS of spring samples measured in the lab show they range from 184 mg/L to 1552 mg/L with the majority of samples between 220 - 430 mg/L. TDS shows a weak correlation (R2 = 0.54) with altitude, where lower TDS is measured in higher altitude samples. These measurements are consistent with high altitude samples representing precipitation and low altitude samples representing shallow groundwater. Location and altitude of springs sampled in this study, as well as those recorded by earlier studies, were used to create a potentiometric surface map in GIS. From the map, water flow direction is inferred to flow mostly from the Abajo Mountains in the southeast towards the Colorado River in the northwest. A transient groundwater flow and solute transport model is developed for a 2-D cross section from the Abajo Mountains in the SE to the Colorado River in the NW. Recharge is applied in the southeast, driving water flow towards the northwest. Most discharge flows into the Colorado River, primarily via seepage through cliff faces. Surface discharge occurs in topographic lows. The flow and solute concentration patterns from the model are generally consistent with field data. Evaporite dissolution varies laterally depending on groundwater flow pattern. Deep groundwater flow patterns and pore pressure data from the model will contribute to an understanding of subsurface salt dissolution and active salt tectonics in the study region. Additionally, the results of this study will help land and water managers protect scarce freshwater resources in this arid desert region.

Association of HeartMate II left ventricular assist device flow estimate with thermodilution cardiac output.

PubMed

Hasin, Tal; Huebner, Marianne; Li, Zhuo; Brown, Daniel; Stulak, John M; Boilson, Barry A; Joyce, Lyle; Pereira, Naveen L; Kushwaha, Sudhir S; Park, Soon J

2014-01-01

Cardiac output (CO) assessment is important in treating patients with heart failure. Durable left ventricular assist devices (LVADs) provide essentially all CO. In currently used LVADs, estimated device flow is generated by a computerized algorithm. However, LVAD flow estimate may be inaccurate in tracking true CO. We correlated LVAD (HeartMate II) flow with thermodilution CO during postoperative care (day 2-10 after implant) in 81 patients (5,616 paired measurements). Left ventricular assist device flow and CO correlated with a low correlation coefficient (r = 0.42). Left ventricular assist device readings were lower than CO measurements by approximately 0.36 L/min, trending for larger difference with higher values. Left ventricular assist device flow measurements showed less temporal variability compared with CO. Grouping for simultaneous measured blood pressure (BP < 60, 60-70, 70-80, 80-90, and ≥90), the correlation of CO with LVAD flow differed (R = 0.42, 0.67, 0.48, 0.32, 0.32, respectively). Indicating better correlation when mean blood pressure is 60 to 70 mm Hg. Left ventricular assist device flow generally trends with measured CO, but large variability exists, hence flow measures should not be assumed to equal with CO. Clinicians should take into account variables such as high CO, BP, and opening of the aortic valve when interpreting LVAD flow readout. Direct flow sensors incorporated in the LVAD system may allow for better estimation.

Comparison of five portable peak flow meters.

PubMed

Takara, Glaucia Nency; Ruas, Gualberto; Pessoa, Bruna Varanda; Jamami, Luciana Kawakami; Di Lorenzo, Valéria Amorim Pires; Jamami, Mauricio

2010-05-01

To compare the measurements of spirometric peak expiratory flow (PEF) from five different PEF meters and to determine if their values are in agreement. Inaccurate equipment may result in incorrect diagnoses of asthma and inappropriate treatments. Sixty-eight healthy, sedentary and insufficiently active subjects, aged from 19 to 40 years, performed PEF measurements using Air Zone, Assess, Galemed, Personal Best and Vitalograph peak flow meters. The highest value recorded for each subject for each device was compared to the corresponding spirometric values using Friedman's test with Dunn's post-hoc (p<0.05), Spearman's correlation test and Bland-Altman's agreement test. The median and interquartile ranges for the spirometric values and the Air Zone, Assess, Galemed, Personal Best and Vitalograph meters were 428 (263-688 L/min), 450 (350-800 L/min), 420 (310-720 L/min), 380 (300-735 L/min), 400 (310-685 L/min) and 415 (335-610 L/min), respectively. Significant differences were found when the spirometric values were compared to those recorded by the Air Zone(R) (p<0.001) and Galemed (p<0.01) meters. There was no agreement between the spirometric values and the five PEF meters. The results suggest that the values recorded from Galemed meters may underestimate the actual value, which could lead to unnecessary interventions, and that Air Zone meters overestimate spirometric values, which could obfuscate the need for intervention. These findings must be taken into account when interpreting both devices' results in younger people. These differences should also be considered when directly comparing values from different types of PEF meters.

High-quality heat flow determination from the crystalline basement of the south-east margin of North China Craton

NASA Astrophysics Data System (ADS)

Jiang, Guangzheng; Tang, Xiaoyin; Rao, Song; Gao, Peng; Zhang, Linyou; Zhao, Ping; Hu, Shengbiao

2016-03-01

Very few of heat flow data have come from the crystalline basement in the North China Craton but rather from boreholes in the sedimentary cover of oil-gas basins. Explorations for hot dry rock (HDR) geothermal resources and porphyry gold deposits in eastern China offer now valuable opportunities to study the terrestrial heat flow in the crystalline basement. In this study, we obtained continuous temperature logs from two boreholes (the LZ borehole with a depth of 3471 m and the DR borehole with a depth of 2179 m) located in the south-east margin of the North China Craton. The boreholes have experienced long shut-in times (442 days and 261 days for the LZ borehole and DR borehole, respectively); thus, it can be expected that the temperature conditions have re-equilibrated after drilling and drill-mud circulation. Rock thermal conductivity and radiogenic heat production were measured for 68 crystalline rock samples from these two boreholes. The measured heat-flow density was determined to be 71.8 ± 2.3 mW m-2 (for the LZ borehole) and 91.5 ± 1.2 mW m-2 (for the DR borehole). The heat flow for the LZ borehole is close to the value of 75 mW m-2 determined in the Chinese Continental Scientific Drilling main hole (CCSD MH), both being in the Sulu-Dabie orogenic belt and thus able to verify each other. The value for the DR borehole is higher than the above two values, which supports former high heat-flow values determined in the Bohai Bay Basin.

Measurement and research on the appearance of tongue board based on modification to discuss centrifugal fan air performance

NASA Astrophysics Data System (ADS)

Jwo, Ching-Song; Cheng, Tseng-Tang; Cho, Hung-Pin; Chiang, Wei-Tang; Chen, Sih-Li; Chen, Chien-Wei; Jian, Ling-You

2011-12-01

This paper presents a reduced fan noise method, with increased fan-benefit analysis of various performances. The experimental approach adopts changes in the outlet in the form of two fans (flat tongue and a V-Type tongue plate) in order to measure the noise under the two forms of value and volume of supply air fan, shaft power consumption, operating current, and static pressure. The results showed that the tongue plate and the V-plane tongue plate noise between the value of the measurement location of 6.7 in the tongue plate in the plane below the noise level is about V-tongue plate 1 ~ 1.5dB (A). Air flow rate testing showed that the flat plate and the V-Type tongue plate between the tongue plate V-Type flow rate value, the measurement location of 3.4 in the tongue plate in the plane was more than the V-Type flow rate tongue plate 5 to 5.5%. Shaft power testing of measurement model 3, and measurement model 4, showed that the tongue plate in the plane V-tongue plate was more than 8%, 5%. The measurement models 3 and 4 and 5 showed more than the V-Type plane tongue plate 1%, 2.7%, and 2.6%. The measurement models 6 and 8 showed that, the flat tongue plate is less than the V-tongue plate of 2.9% and 2.3%. Static pressure testing showed that the flat tongue plate in particular measurement models (3,4,8,9), the static value of V-tongue plate than the 11.1% higher, respectively, 9%, 4.3%, and 3.7%. The results summarized above suggest that, in the specific measurement points, when parallel to the tongue plate the V-tongue board has better performance.

Instrumental record of debris flow initiation during natural rainfall: Implications for modeling slope stability

USGS Publications Warehouse

Montgomery, D.R.; Schmidt, K.M.; Dietrich, W.E.; McKean, J.

2009-01-01

The middle of a hillslope hollow in the Oregon Coast Range failed and mobilized as a debris flow during heavy rainfall in November 1996. Automated pressure transducers recorded high spatial variability of pore water pressure within the area that mobilized as a debris flow, which initiated where local upward flow from bedrock developed into overlying colluvium. Postfailure observations of the bedrock surface exposed in the debris flow scar reveal a strong spatial correspondence between elevated piezometric response and water discharging from bedrock fractures. Measurements of apparent root cohesion on the basal (Cb) and lateral (Cl) scarp demonstrate substantial local variability, with areally weighted values of Cb = 0.1 and Cl = 4.6 kPa. Using measured soil properties and basal root strength, the widely used infinite slope model, employed assuming slope parallel groundwater flow, provides a poor prediction of hydrologie conditions at failure. In contrast, a model including lateral root strength (but neglecting lateral frictional strength) gave a predicted critical value of relative soil saturation that fell within the range defined by the arithmetic and geometric mean values at the time of failure. The 3-D slope stability model CLARA-W, used with locally observed pore water pressure, predicted small areas with lower factors of safety within the overall slide mass at sites consistent with field observations of where the failure initiated. This highly variable and localized nature of small areas of high pore pressure that can trigger slope failure means, however, that substantial uncertainty appears inevitable for estimating hydrologie conditions within incipient debris flows under natural conditions. Copyright 2009 by the American Geophysical Union.

Estimating recharge rates with analytic element models and parameter estimation

USGS Publications Warehouse

Dripps, W.R.; Hunt, R.J.; Anderson, M.P.

2006-01-01

Quantifying the spatial and temporal distribution of recharge is usually a prerequisite for effective ground water flow modeling. In this study, an analytic element (AE) code (GFLOW) was used with a nonlinear parameter estimation code (UCODE) to quantify the spatial and temporal distribution of recharge using measured base flows as calibration targets. The ease and flexibility of AE model construction and evaluation make this approach well suited for recharge estimation. An AE flow model of an undeveloped watershed in northern Wisconsin was optimized to match median annual base flows at four stream gages for 1996 to 2000 to demonstrate the approach. Initial optimizations that assumed a constant distributed recharge rate provided good matches (within 5%) to most of the annual base flow estimates, but discrepancies of >12% at certain gages suggested that a single value of recharge for the entire watershed is inappropriate. Subsequent optimizations that allowed for spatially distributed recharge zones based on the distribution of vegetation types improved the fit and confirmed that vegetation can influence spatial recharge variability in this watershed. Temporally, the annual recharge values varied >2.5-fold between 1996 and 2000 during which there was an observed 1.7-fold difference in annual precipitation, underscoring the influence of nonclimatic factors on interannual recharge variability for regional flow modeling. The final recharge values compared favorably with more labor-intensive field measurements of recharge and results from studies, supporting the utility of using linked AE-parameter estimation codes for recharge estimation. Copyright ?? 2005 The Author(s).

[Non-invasive estimation of aortic flow by local electrical impedance changes].

PubMed

Okuda, N; Ohashi, N; Yamada, M; Fujinami, T

1986-09-01

Aortic flow velocity was measured by catheter-tip flow transducer in 25 patients who underwent left cardiac catheterization for non-invasive estimates by the impedance method. Disk electrodes were attached to the skin at the levels of the second thoracic vertebra in the posterior median line and the V8 lead position for electrocardiography. Alternating current, 350 micro-amperes, 50 KHz constant, was applied to the outer electrode, and impedance changes were detected via the inner electrode. The e wave, or height of the first derivative dz/dt wave of the electrical impedance was lower in cases of old myocardial infarction and higher in cases of aortic valve regurgitation, as compared with the values of the healthy control group. The time lag between the start of the upward deflection and the peak value of the dz/dt wave coincided with that of the aortic flow curve as measured at the aortic arch and descending aorta. These time lags were about 20 to 30 msec as compared with the ascending aortic flow curve, and were -20 to -30 msec as compared with the abdominal aortic flow curve. There was a close correlation between the maximum flow velocity measured at the aortic arch and the height of the e waves. The regression equation was: Y = 0.21X - 1.53, r = 0.88, p less than 0.01. These data suggest that the first derivative of electrical impedance change as obtained by the disk electrode method reflects aortic flow at the arch and descending aorta.

[Value of fractional flow reserve measurement in endovascular therapy for patients with Stanford B type aortic dissection complicated with renal blood flow injury].

PubMed

Guo, Xi; Li, Peng; Liu, Guangrui; Huang, Xiaoyong; Yong, Qiang; Wang, Guoqin; Huang, Lianjun

2015-10-01

To analyze the value of fractional flow reserve (FFR) measurement on endovascular therapy for patients with renal artery stenosis. Clinical data of 12 patients with Stanford B type aortic dissection complicated with renal blood flow injury in Anzhen hospital hospitalized from May 2013 to February 2014 were retrospectively analyzed. Renal artery angiography was performed and fractional flow reserve (FFR) was measured before Thoracic endovascular aortic repair. After operation, renal artery FFR was measured again, and renal artery stenting was performed in patients with FFR ≤ 0.90 or average pressure difference between proximal and distal of renal artery > 20 mmHg (1 mmHg = 0.133 kPa) and not applied for patients with FFR > 0.90.The patients were then subsequently followed up clinically. Kidney function were measured after 1 month, and contrast-enhanced ultrasonography data were obtained at 1 and 3 months later, respectively. The FFR of 1 patient was 0.90, while the FFR of other patients were less than 0.90 before thoracic endovascular aortic repair. After the procedure,the angiography showed that the blood flow of renal artery in 8 patients were fluency, and the FFR index was over 0.90. There were 4 patients with FFR less than 0.90. After renal artery stenting, the FFR of these 4 patients were all above 0.90. Compared with pre-procedure, blood urea nitrogen ((8.84 ± 3.99) mmol/L vs. (5.18 ± 1.69) mmol/L, P = 0.011) and uric acid ((359.3 ± 77.3) µmol/L vs. (276.9 ± 108.3) µmol/L, P = 0.008) decreased significantly after 1 month, and there was no significant difference in serum creatinine (P = 0.760). Contrast-enhanced ultrasonography results showed that blood flow of renal artery were fluency after 1 month and 3 months. In patients with aortic dissection complicating renal blood flow injury, the FFR measurement is meaningful in evaluating the blood flow status of target organs and guide the endovascular revascularization.

Diagnostic performance of labial minor salivary gland flow measurement for assessment of xerostomia.

PubMed

Satoh-Kuriwada, Shizuko; Iikubo, Masahiro; Shoji, Noriaki; Sakamoto, Maya; Sasano, Takashi

2012-08-01

Minor salivary gland flow rate (MF) has been proposed as a key feature of xerostomia (subjective feeling of dry mouth). To assess its diagnostic performance, MF was compared in xerostomia and control subjects. Sixty-six subjects with xerostomia and 30 controls were enrolled. MF was measured in the lower labial mucosa using the iodine-starch filter paper method. Stimulated whole salivary flow rates were also measured using the gum test (stimulated-WF). Both labial-MF and stimulated-WF were significantly lower in xerostomia subjects than in controls. There was a positive correlation between labial-MF and stimulated-WF in control but not xerostomia subjects. In xerostomia subjects compared to controls, there was a significantly larger reduction in labial-MF than in stimulated-WF. Xerostomia was most accurately diagnosed using a labial-MF cutoff value of 0.25 μL/cm(2)/min. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy at this cutoff value were 1.00, 0.87, 0.93, 1.00, and 0.96, respectively. Compared to respective values of 0.64, 1.00, 1.00, 0.56, and 0.75 for stimulated-WF at the traditional cutoff of 1.0 mL/min, these data indicate the higher sensitivity, negative predictive value, and diagnostic accuracy of labial-MF. Xerostomia was more strongly related to reduction of labial-MF than to that of stimulated-WF. Xerostomia was most likely triggered at a labial-MF cut-off value of 0.25 μL/cm(2)/min based on results from the iodine-starch method. Copyright © 2012 Elsevier Ltd. All rights reserved.

MODFLOW-2000, The U.S. Geological Survey Modular Ground-Water Model - User Guide to Modularization Concepts and the Ground-Water Flow Process

USGS Publications Warehouse

Harbaugh, Arlen W.; Banta, Edward R.; Hill, Mary C.; McDonald, Michael G.

2000-01-01

MODFLOW is a computer program that numerically solves the three-dimensional ground-water flow equation for a porous medium by using a finite-difference method. Although MODFLOW was designed to be easily enhanced, the design was oriented toward additions to the ground-water flow equation. Frequently there is a need to solve additional equations; for example, transport equations and equations for estimating parameter values that produce the closest match between model-calculated heads and flows and measured values. This report documents a new version of MODFLOW, called MODFLOW-2000, which is designed to accommodate the solution of equations in addition to the ground-water flow equation. This report is a user's manual. It contains an overview of the old and added design concepts, documents one new package, and contains input instructions for using the model to solve the ground-water flow equation.

Compressible flow across narrow passages: Comparison of theory and experiment for face seals

NASA Technical Reports Server (NTRS)

Allen, G. P.; Wisander, D. W.; Hady, W. F.

1978-01-01

Computer calculation for determining compressible flow across radial face seals were compared with measured results obtained in a seal simulator rig at pressure ratios to 0.9 (ambient pressure/sealed pressure). In general, the measured and calculated leakages across the seal dam agreed within 3 percent. The resultant loss coefficient, dependent upon the pressure ratio, ranged from 0.47 to 0.68. The calculated pressures were within 2.5 N/cu um of the measured values.

Technique for measuring gas conversion factors

NASA Technical Reports Server (NTRS)

Singh, J. J.; Sprinkle, D. R. (Inventor)

1985-01-01

A method for determining hydrocarbon conversion factors for a flowmeter. A mixture of air, O2 and C sub x H sub y is burned and the partial paressure of O2 in the resulting gas is forced to equal the partial pressure of O2 in air. The flowrate of O2 flowing into the mixture is measured by flowmeter and the flowrate of C sub x H sub y flowing into the mixture is measured by the flowmeter conversion factor is to be determined. These measured values are used to calculate the conversion factor.

A comparison of daily water use estimates derived from constant-heat sap-flow probe values and gravimetric measurements in pot-grown saplings.

Treesearch

K.A. McCulloh; K. Winter; F.C. Meinzer; M. Garcia; J. Aranda; Lachenbruch B.

2007-01-01

The use of Granier-style heat dissipation sensors to measure sap flow is common in plant physiology, ecology, and hydrology. There has been concern that any change to the original Granier design invalidates the empirical relationship between sap flux density and the temperature difference between the probes. We compared daily water use estimates from gravimetric...

Application of laser Doppler velocimeter to chemical vapor laser system

NASA Technical Reports Server (NTRS)

Gartrell, Luther R.; Hunter, William W., Jr.; Lee, Ja H.; Fletcher, Mark T.; Tabibi, Bagher M.

1993-01-01

A laser Doppler velocimeter (LDV) system was used to measure iodide vapor flow fields inside two different-sized tubes. Typical velocity profiles across the laser tubes were obtained with an estimated +/-1 percent bias and +/-0.3 to 0.5 percent random uncertainty in the mean values and +/-2.5 percent random uncertainty in the turbulence-intensity values. Centerline velocities and turbulence intensities for various longitudinal locations ranged from 13 to 17.5 m/sec and 6 to 20 percent, respectively. In view of these findings, the effects of turbulence should be considered for flow field modeling. The LDV system provided calibration data for pressure and mass flow systems used routinely to monitor the research laser gas flow velocity.

Heat Flow Budget of the Gulf of California Rift: Preliminary Results of a High Resolution Survey Across the Wagner Basin

NASA Astrophysics Data System (ADS)

Negrete-Aranda, R.; Neumann, F.; Harris, R. N.; Contreras, J.; Gonzalez-Fernandez, A.; Sclater, J. G.

2016-12-01

The thermal regime exerts a primary control on rift dynamics and mode of extension for continental lithosphere. We present three heat-flow profiles across the southern terminus of the Cerro Prieto fault, in the northern Gulf of California. The longest profile is 42 km and has a measurement spacing of 1 km that spans the hanging-wall block (Wagner basin) and the footwall block of that fault. Measurements were taken with a 6.5 m long Fielax, violin-bow probe. Most measurements are of good quality, i.e., the probe fully penetrated sediments and measurements were stable enough to perform reliable inversion for heat flow and thermal properties. However, it was necessary to perform numerous corrections due to environmental phenomena related the copious sedimentation in the area, and seasonal changes in water temperature. Our measurements indicate the total throughput across the central rift and its east shoulder is 15 KW/m per meter of rift length. More important, heat flow values cluster in three distinct spatial groups: (i) heat flow in the well sedimented depocenter of the Wagner basin is approximately 200 mW/m2; (ii) the footwall block heat-flow is approximately 400 mW/m2; and (iii) heat flow across the fault zone is very high, up to 5,000 mW/m2. Our interpretation is that the former value represents the background conductive heat flow in the rift whereas heat flow across the fault represents advective heat transport by hydrothermal fluids. The high heat flow in the footwall block of the Cerro Prieto fault might be result of both conductive and advective heat transfer by fluid seepage from the basin. These data provide evidence that fluids from deep magma bodies transported along faults assist rifting in the northern Gulf of California. We are exploring how fluids may play a role in weakening the lithosphere and help localizing/delocalizing strain along major transforms and numerous normal faults observed in the area.

Measurement of glomerular filtration rate, renal plasma flow, and endogenous creatinine clearance in cheetahs (Acinonyx jubatus jubatus).

PubMed

Holder, Erin Hall; Citino, Scott B; Businga, Nancy; Cartier, Leslie; Brown, Scott A

2004-06-01

Glomerular filtration rate (GFR), renal plasma flow (RPF), and the endogenous creatinine clearance (CCr) rate were determined in 13 captive cheetahs, Acinonyx jubatus jubatus (seven females and six males, 1.5-7.5 yr of age, x = 5.02 yr), during general anesthesia with Telazol and isoflurane by measuring the urinary clearances of inulin, para-aminohipppuric acid, and endogenous creatinine, respectively. Methods to determine GFR, RPF, and endogenous CCr in captive cheetahs were evaluated, and the relationship between GFR and CCr for this species was determined. The GFR and the RPF were stable during the procedure, with mean values of 1.59+/-0.17 ml/min/kg body weight and 5.12+/-1.15 ml/min/kg body weight, respectively. Although the mean value for CCr (1.47+/-0.20 ml/min/kg body weight) was significantly less than the corresponding value for GFR, the mean difference (0.11+/-0.02 ml/min/kg weight) between the two measurements was slight, and the values were highly correlated (R2 = 0.928; P < 0.0001). The measurement of CCr in cheetahs should provide a reliable estimate of GFR, facilitating the early detection of renal disease in this species.

A discharge flow-photoionization mass spectrometric study of the FO(X 2 Pi i) radical. Photoionization efficiency spectrum and ionization energy

NASA Technical Reports Server (NTRS)

Zhang, Zhengyu; Kuo, Szu-Cherng; Klemm, R. Bruce; Monks, Paul S.; Stief, Louis J.

1994-01-01

Photoionization efficiency spectra of FO were measured over the wavelength range 80.0-100.0 nm and in the ionization threshold region, 94.0-100.0 nm, using a discharge flow-photoionization mass spectrometer apparatus coupled to a synchrotron radiation source. FO was generated by the reaction of F2P atoms with NO3 and via a F2O2 discharge. A value of 12.78 +/- 0.03 eV was obtained for the adiabatic ionization energy of FO from photoion thresholds which corresponds to FO(+)(X 3 Sigma -) from FO(X 2 Pi i). These results, which are the first to be obtained by direct Photo-ionization mass spectrometry (PIMS) measurements, corroborate those of a photoelectron spectroscopy (PES) study; however, the ionization energy determined here is free from interferences due to other species which complicated the PES measurement. A value of 109.5 +/- 8.0 kJ/mol for Delta f H 0 298(FO) is computed from the present value of IE(FO) and a previous appearance energy measurement, and a value for the proton affinity of FO is calculated to be 511.5 +/- 10.0 kJ/mol.

The measurements of water flow rates in the straight microchannel based on the scanning micro-PIV technique

NASA Astrophysics Data System (ADS)

Wang, H. L.; Han, W.; Xu, M.

2011-12-01

Measurement of the water flow rate in microchannel has been one of the hottest points in the applications of microfluidics, medical, biological, chemical analyses and so on. In this study, the scanning microscale particle image velocimetry (scanning micro-PIV) technique is used for the measurements of water flow rates in a straight microchannel of 200μm width and 60μm depth under the standard flow rates ranging from 2.481μL/min to 8.269μL/min. The main effort of this measurement technique is to obtain three-dimensional velocity distribution on the cross sections of microchannel by measuring velocities of the different fluid layers along the out-of-plane direction in the microchannel, so the water flow rates can be evaluated from the discrete surface integral of velocities on the cross section. At the same time, the three-dimensional velocity fields in the measured microchannel are simulated numerically using the FLUENT software in order to verify the velocity accuracy of measurement results. The results show that the experimental values of flow rates are well consistent to the standard flow rates input by the syringe pump and the compared results between numerical simulation and experiment are consistent fundamentally. This study indicates that the micro-flow rate evaluated from three-dimensional velocity by the scanning micro-PIV technique is a promising method for the micro-flow rate research.

Quantitative measurement of regional blood flow with gadolinium diethylenetriaminepentaacetate bolus track NMR imaging in cerebral infarcts in rats: validation with the iodo[14C]antipyrine technique.

PubMed Central

Wittlich, F; Kohno, K; Mies, G; Norris, D G; Hoehn-Berlage, M

1995-01-01

NMR bolus track measurements were correlated with autoradiographically determined regional cerebral blood flow (rCBF). The NMR method is based on bolus infusion of the contrast agent gadolinium diethylenetriaminepentaacetate and high-speed T*2-sensitive NMR imaging. The first pass of the contrast agent through the image plane causes a transient decrease of the signal intensity. This time course of the signal intensity is transformed into relative concentrations of the contrast agent in each pixel. The mean transit time and relative blood flow and volume are calculated from such indicator dilution curves. We investigated whether this NMR technique correctly expresses the relative rCBF. The relative blood flow data, calculated from NMR bolus track experiments, and the absolute values of iodo[14C]antipyrine autoradiography were compared. A linear relationship was observed, indicating the proportionality of the transient NMR signal change with CBF. Excellent interindividual reproducibility of calibration constants is observed (r = 0.963). For a given NMR protocol, bolus track measurements calibrated with autoradiography after the experiment allow determination of absolute values for rCBF and regional blood volume. Images Fig. 2 Fig. 3 PMID:7892189

Effect of altitude on spirometric parameters and the performance of peak flow meters.

PubMed Central

Pollard, A. J.; Mason, N. P.; Barry, P. W.; Pollard, R. C.; Collier, D. J.; Fraser, R. S.; Miller, M. R.; Milledge, J. S.

1996-01-01

BACKGROUND: Portable peak flow meters are used in clinical practice for measurement of peak expiratory flow (PEF) at many different altitudes throughout the world. Some PEF meters are affected by gas density. This study was undertaken to establish which type of meter is best for use above sea level and to determine changes in spirometric measurements at altitude. METHODS: The variable orifice mini-Wright peak flow meter was compared with the fixed orifice Micro Medical Microplus turbine microspirometer at sea level and at Everest Base Camp (5300 m). Fifty one members of the 1994 British Mount Everest Medical Expedition were studied (age range, 19-55). RESULTS: Mean forced vital capacity (FVC) fell by 5% and PEF rose by 25.5%. However, PEF recorded with the mini-Wright peak flow meter underestimated PEF by 31%, giving readings 6.6% below sea level values. FVC was lowest in the mornings and did not improve significantly with acclimatisation. Lower PEF values were observed on morning readings and were associated with higher acute mountain sickness scores, although the latter may reflect decreased effort in those with acute mountain sickness. There was no change in forced expiratory volume in one second (FEV1) at altitude when measured with the turbine microspirometer. CONCLUSIONS: The cause of the fall in FVC at 5300 m is unknown but may be attributed to changes in lung blood volume, interstitial lung oedema, or early airways closure. Variable orifice peak flow meters grossly underestimate PEF at altitude and fixed orifice devices are therefore preferable where accurate PEF measurements are required above sea level. PMID:8711651

Exploring imperfect squeezing flow measurements in a Teflon geometry for semisolid foods.

PubMed

Terpstra, M E J; Janssen, A M; Linden, E van der

2007-11-01

The method of imperfect lubricated squeezing flow in a Teflontrade mark geometry has been explored for the characterization of elongational behavior of custard and mayonnaise. Two Newtonian products, one of low (0.07 Pas) and one of high (18 Pas) shear viscosity, were used as references. Measurements of custards and mayonnaises did not behave according to either the theory of lubricated or nonlubricated squeezing flow, as there were effects of the initial sample height and compression speed. Also, calculated values for the flow index were not as we had expected. The same was true for the Newtonian samples. An important factor explaining the effect of compression speed was the presence of a certain amount of friction, rendering both lubricated theory and nonlubricated theory nonapplicable. Correcting for (pseudo-) thixotropic behavior of custard and mayonnaise appears to be an effective way of obtaining realistic values for the flow index. The presence of buoyancy also affected the results, especially in the case of low viscous products and the effect of initial sample height. Other factors that played a role in the results were yield stress for custard and mayonnaise and instrumental artifacts associated with the imperfect setup of the measurement, especially for the highly viscous products. Quantitatively correcting the results for all of these factors is not possible at this point. Although the imperfect squeezing flow technique in a Teflon geometry is a very practical way to measure semisolids such as custard and mayonnaise under (partly) elongational deformation, the results should be regarded as more qualitative than quantitative.

MRI measurements of intracranial pressure in the upright posture: The effect of the hydrostatic pressure gradient.

PubMed

Alperin, Noam; Lee, Sang H; Bagci, Ahmet M

2015-10-01

To add the hydrostatic component of the cerebrospinal fluid (CSF) pressure to magnetic resonance imaging (MRI)-derived intracranial pressure (ICP) measurements in the upright posture for derivation of pressure value in a central cranial location often used in invasive ICP measurements. Additional analyses were performed using data previously collected from 10 healthy subjects scanned in supine and sitting positions with a 0.5T vertical gap MRI scanner (GE Medical). Pulsatile blood and CSF flows to and from the brain were quantified using cine phase-contrast. Intracranial compliance and pressure were calculated using a previously described method. The vertical distance between the location of the CSF flow measurement and a central cranial location was measured manually in the mid-sagittal T1 -weighted image obtained in the upright posture. The hydrostatic pressure gradient of a CSF column with similar height was then added to the MR-ICP value. After adjustment for the hydrostatic component, the mean ICP value was reduced by 7.6 mmHg. Mean ICP referenced to the central cranial level was -3.4 ± 1.7 mmHg compared to the unadjusted value of +4.3 ± 1.8 mmHg. In the upright posture, the hydrostatic pressure component needs to be added to the MRI-derived ICP values for compatibility with invasive ICP at a central cranial location. © 2015 Wiley Periodicals, Inc.

Electromagnetic probe technique for fluid flow measurements

NASA Technical Reports Server (NTRS)

Arndt, G. D.; Carl, J. R.

1994-01-01

The probes described herein, in various configurations, permit the measurement of the volume fraction of two or more fluids flowing through a pipe. Each probe measures the instantaneous relative dielectric constant of the fluid in immediate proximity. As long as separation of the relative dielectric constant of the fluid is possible, several or even many fluids can be measured in the same flow stream. By using multiple probes, the velocity of each fluid can generally be determined as well as the distribution of each constituent in the pipe. The values are determined by statistical computation. There are many potential applications for probes of this type in industry and government. Possible NASA applications include measurements of helium/hydrazine flow during rocket tests at White Sands, liquid/gas flow in hydrogen or oxygen lines in Orbiter engines, and liquid/gaseous Freon flow in zero gravity tests with the KS135 aircraft at JSC. Much interest has been shown recently by the oil industry. In this a good method is needed to measure the fractions of oil, water, and natural gas flowing in a pipeline and the velocity of each. This particular problem involves an extension of what has been developed to date and our plans to solve this problem will be discussed herein.

Evaluation of exhaled nitric oxide in schoolchildren at different exhalation flow rates.

PubMed

Pedroletti, Christophe; Zetterquist, Wilhelm; Nordvall, Lennart; Alving, Kjell

2002-09-01

Nitric oxide (NO) in exhaled air is believed to reflect allergic inflammation in the airways. Measured levels of exhaled NO vary with the exhaled flow rate, which therefore must be standardized. The aim of this study was to estimate the optimal exhalation flow rate when measuring NO in exhaled air. We studied 15 asthmatic children (8-18 y) with elevated NO levels and 15 age-matched controls and focused on how the quality of the NO curve profile, the discriminatory power, and the reproducibility were influenced by the exhalation flow rate. We used an on-line system for NO measurements at six different exhalation flow rates in the interval of 11-382 mL/s. The fraction of exhaled nitric oxide (FENO) was highly flow-dependent as was expected. Intermediate flow rates yielded a flat and stable NO plateau and were considerably easier to interpret than those obtained at the highest and lowest flow rates. The ratio of FENO between asthmatics and controls was lower at higher flow rates and a considerable overlap in NO values was demonstrated at all flow rates except 50 mL/s. The reproducibility was much lower at more extreme flow rates and was best at 50 mL/s. We conclude that a target exhalation flow rate of approximately 50 mL/s is to be preferred using the single-breath method for on-line NO measurements in schoolchildren.

A Comparison of Theory and Experiment for High-speed Free-molecule Flow

NASA Technical Reports Server (NTRS)

Stalder, Jackson R; Goodwin, Glen; Creager, Marcus O

1951-01-01

A comparison is made of free-molecule-flow theory with the results of wind-tunnel tests performed to determine the drag and temperature-rise characteristics of a transverse circular cylinder. The measured values of the cylinder center-point temperature confirmed the salient point of the heat-transfer analysis which was the prediction that an insulated cylinder would attain a temperature higher than the stagnation temperature of the stream. Good agreement was obtained between the theoretical and the experimental values for the drag coefficient.

40 CFR 1065.546 - Validation of minimum dilution ratio for PM batch sampling.

Code of Federal Regulations, 2010 CFR

2010-07-01

... flows and/or tracer gas concentrations for transient and ramped modal cycles to validate the minimum... mode-average values instead of continuous measurements for discrete mode steady-state duty cycles... molar flow data. This involves determination of at least two of the following three quantities: Raw...

SVM-based multisensor data fusion for phase concentration measurement in biomass-coal co-combustion

NASA Astrophysics Data System (ADS)

Wang, Xiaoxin; Hu, Hongli; Jia, Huiqin; Tang, Kaihao

2018-05-01

In this paper, the electrical method combines the electrostatic sensor and capacitance sensor to measure the phase concentration of pulverized coal/biomass/air three-phase flow through data fusion technology. In order to eliminate the effects of flow regimes and improve the accuracy of the phase concentration measurement, the mel frequency cepstrum coefficient features extracted from electrostatic signals are used to train the Continuous Gaussian Mixture Hidden Markov Model (CGHMM) for flow regime identification. Support Vector Machine (SVM) is introduced to establish the concentration information fusion model under identified flow regimes. The CGHMM models and SVM models are transplanted on digital signal processing (DSP) to realize on-line accurate measurement. The DSP flow regime identification time is 1.4 ms, and the concentration predict time is 164 μs, which can fully meet the real-time requirement. The average absolute value of the relative error of the pulverized coal is about 1.5% and that of the biomass is about 2.2%.

Parametres pour l'instabilite fluidelastique: Derivees de stabilite et amortissement diphasique

NASA Astrophysics Data System (ADS)

Charreton, Constant

Heat exchangers and steam generators are crucial components in nuclear power plants. Water heated by nuclear fission is flowing through thousands of tubes inside a steam generator. Heat is transmitted to a second water network, external to the tubes. Steam is generated from the water of the secondary to power the turbines that produce electrical power. In this process, two-phase cross flow across the tubes causes several excitation phenomena. Vibration induced on the tubes can compromise the structural integrity of the steam generator, and can lead to power plant shutdowns. Better understanding of parameters at stake would lead to improved power plant safety and reliability. Fluidelastic instability is without doubt one of the most destructive vibration phenomena. It causes the steam generator tubes to collide against one another. This can lead to premature wear on the tubes, cracks due to fatigue and eventually, leaks leading to radioactive water contamination. Therefore, predicting conditions leading to fluidelastic instability would allow to control the damage on the tubes. In this thesis, we aim at identifying the key parameters to predict fluidelastic instability. To do so, a theoretical approach is based on the quasi-steady model. It is shown that the equation used to predict fluidelastic instability comprises two parameters that are hard to characterize. There is, on one hand, the derivative of the lift coefficient on a cylinder, and damping on the other hand. The main objective of this project is to measure these parameters experimentally. Knowing that the sign of the lift coefficient derivative is a sufficient indicator of fluidelastic instability, this derivative was measured. The experiments were carried out on the center tube of an array. The flow is single-phase and values of Reynolds number are low to moderate, thus filling a gap in the literature. Indeed, the lift coefficient derivative is known for high values of the Reynolds number only. Meanwhile, numerical methods are developed. They are based on the direct resolution of Navier-Stokes equations with the finite-element method, and on potential flow theory. Results for the lift coefficient derivative are compared to the measurements. Furthermore, the influence of geometric parameters of the array are investigated. The trend in the results show that the derivative of the lift coefficient becomes Reynolds independent for high values. From the literature and the measurements, a relationship is proposed for the lift coefficient derivative with respect to the Reynolds number. Values are injected in the quasi-steady model to predict the critical velocity for the onset of instability of a single flexible tube. Stability maps for various Reynolds numbers are proposed, using typical values for the tube damping. However, the maps do not compare well with critical velocities found in the literature for high values of the Reynolds number. Stability tests would be necessary to confirm the validity of the maps for low Reynolds, as fluidelastic has never been investigated in this range of Reynolds number. Yet, for high values of the Reynolds number, it seems like the quasi-steady model fails to predict the behavior of the experiments. An accurate value for the total damping of a tube is required to locate instability results on a map. However, in steam generators subjected to two-phase flow, damping on a tube is much more important than for single-phase flow. Yet, its origin is unknown. Therefore, we measured two-phase damping for internal flow using a specific test section. Indeed, a few studies on two-phase flow suggest that the damping mechanism is the same for a tube in cross-flow and for a tube subjected to internal flow. The present study focuses on the physics underlying the two-phase damping mechanism. The test bench consists of a sliding rigid tube subjected to upward internal two-phase flow. It essentially is a mass-spring system subjected to a transverse sinusoidal force. The damping is extracted from the frequency response function of the tube. Meanwhile, gas phase motion is characterized through video processing of the oscillating tube. The relative amplitude of the gas phase is related to two-phase flow damping values via a model of the forces acting on the bubbles. Varying excitation parameters such as frequency and excitation force confirms that two-phase damping is a viscous (velocity dependent) dissipation mechanism. Its direct relation with flow pattern transitions was confirmed. Furthermore, the combination of the videos and the analytical model suggests that the power dissipated by the drag force on the bubbles is significant in the two-phase damping mechanism. However, the model over-predicts the amplitude of the gas phase. This suggests that pseudo-turbulence generated by the motion of the tube is to be considered. The results of this study form an experimental database that can be used as input for fluidelastic instability models. Particularly, two-phase flow experiments will eventually help validating numerical methods, regarding the damping as well as the behavior of the gas phase. This work contributes to modeling and understanding two-phase flow induced vibration.

Flow Rates Measurement and Uncertainty Analysis in Multiple-Zone Water-Injection Wells from Fluid Temperature Profiles

PubMed Central

Reges, José E. O.; Salazar, A. O.; Maitelli, Carla W. S. P.; Carvalho, Lucas G.; Britto, Ursula J. B.

2016-01-01

This work is a contribution to the development of flow sensors in the oil and gas industry. It presents a methodology to measure the flow rates into multiple-zone water-injection wells from fluid temperature profiles and estimate the measurement uncertainty. First, a method to iteratively calculate the zonal flow rates using the Ramey (exponential) model was described. Next, this model was linearized to perform an uncertainty analysis. Then, a computer program to calculate the injected flow rates from experimental temperature profiles was developed. In the experimental part, a fluid temperature profile from a dual-zone water-injection well located in the Northeast Brazilian region was collected. Thus, calculated and measured flow rates were compared. The results proved that linearization error is negligible for practical purposes and the relative uncertainty increases as the flow rate decreases. The calculated values from both the Ramey and linear models were very close to the measured flow rates, presenting a difference of only 4.58 m³/d and 2.38 m³/d, respectively. Finally, the measurement uncertainties from the Ramey and linear models were equal to 1.22% and 1.40% (for injection zone 1); 10.47% and 9.88% (for injection zone 2). Therefore, the methodology was successfully validated and all objectives of this work were achieved. PMID:27420068

Simulated Microgravity Increases Cutaneous Blood Flow in the Head and Leg of Humans

NASA Technical Reports Server (NTRS)

Stout, M. Shannon; Watenpaugh, Donald E.; Breit, Gregory A.; Hargens, Alan R.

1995-01-01

The cutaneous micro-circulation vasodilates during acute 6 deg. head-down tilt (HDT, simulated microgravity) relative to upright conditions, more in the lower body than in the upper body. We expected that relative magnitudes of and differences between upper and lower body cutaneous blood flow elevation would be sustained during initial acclimation to simulated microgravity. We measured cutaneous micro-vascular blood flow with laser-Doppler flowmetry at the leg (over the distal tibia) and cheek (over the zygomatic arch) of eight healthy men before, during, and after 24 h of HDT. Results were calculated as a percentage of baseline value (100% measured during pre-tilt upright sitting). Cutaneous blood flow in the cheek increased significantly to 165 +/- 37% (mean + SE, p less than 0.05) at 9-12 h HDT, then returned to near baseline values by 24 h HDT (114 +/- 29%, NSD), despite increased local arterial pressure. Microvascular flow in the leg remained significantly elevated above baseline throughout 24 h HDT (427 +/- 85% at 3 h HDT and 215 +/- 142% at 24 h HDT, p less than 0.05). During the 6-h upright sitting recovery period, cheek and leg blood flow levels returned to near pre-tilt baseline values. Because hydrostatic effects of HDT increase local arterial pressure at the carotid sinus, baroreflex-mediated withdrawal of sympathetic tone probably contributed to increased microvascular flows at the head and leg during HDT. In the leg, baroreflex effects combined with minimal stimulation of local veno-arteriolar and myogenic autoregulatory vasoconstriction to elicit relatively larger and more sustained increases in cutaneous flow during HDT. In the cheek, delayed myogenic vasoconstriction and/or humoral effects apparently compensated for flow elevation by 24 h of HDT. Therefore, localized vascular adaptations to gravity probably explain differences in acclimation of lower and upper body blood flow to HDT and actual microgravity.

Revisiting Maxwell’s accommodation coefficient: A study of nitrogen flow in a silica microtube across all flow regimes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lei, Wenwen, E-mail: wlei@physics.usyd.edu.au; McKenzie, David R., E-mail: d.mckenzie@physics.usyd.edu.au

2014-12-15

Gas flows have been studied quantitatively for more than a hundred years and have relevance in modern fields such as the control of gas inputs to processes, the measurement of leak rates and the separation of gaseous species. Cha and McCoy have derived a convenient formula for the flow of an ideal gas applicable across a wide range of Knudsen numbers (Kn) that approaches the Navier–Stokes equations at small Kn and the Smoluchowski extension of the Knudsen flow equation at large Kn. Smoluchowski’s result relies on the Maxwell definition of the tangential momentum accommodation coefficient α, recently challenged by Aryamore » et al. We measure the flow rate of nitrogen gas in a smooth walled silica tube across a wide range of Knudsen numbers from 0.0048 to 12.4583. We find that the nitrogen flow obeys the Cha and McCoy equation with a large value of α, unlike carbon nanotubes which show flows consistent with a small value of α. Silica capillaries are therefore not atomically smooth. The flow at small Kn has α=0.91 and at large Kn has α close to one, consistent with the redefinition of accommodation coefficient by Arya et al., which also resolves a problem in the literature where there are many observations of α of less than one at small Kn and many equal to one at large Kn. Silica capillaries are an excellent choice for an accurate flow control system. - Highlights: • First experimental study on flow rate across all flow regimes in a well-defined microtube. • Extend Cha and McCoy theory for molecular flow regime. • Demonstrate the Maxwell accommodation coefficient is different in the slip and molecular flow regimes.« less

Age, gender, and voided volume dependency of peak urinary flow rate and uroflowmetry nomogram in the Indian population

PubMed Central

Kumar, Vikash; Dhabalia, Jayesh V.; Nelivigi, Girish G.; Punia, Mahendra S.; Suryavanshi, Manav

2009-01-01

Objectives: The objective of this study was measurement of urine flow parameters by a non invasive urodynamic test. Variation of flow rates based on voided volume, age, and gender are described. Different nomograms are available for different populations and racial differences of urethral physiology are described. Currently, there has been no study from the Indian population on uroflow parameters. So the purpose of this study was to establish normal reference ranges of maximum and average flow rates, to see the influence of age, gender, and voided volume on flow rates, and to chart these values in the form of a nomogram. Methods: We evaluated 1,011 uroflowmetry tests in different age groups in a healthy population (healthy relatives of our patients) 16-50 year old males, >50 year old males, 5-15 year old children, and >15 year pre-menopausal and post-menopausal females. The uroflowmetry was done using the gravitimetric method. Flow chart parameters were analyzed and statistical calculations were used for drawing uroflow nomograms. Results: Qmax values in adult males were significantly higher than in the elderly and Qmax values in young females were significantly higher than in young males. Qmax values in males increased with age until 15 years old; followed by a slow decline until reaching 50 years old followed by a rapid decline after 50 years old even after correcting voided volume. Qmax values in females increased with age until they reached age 15 followed by decline in flow rate until a pre-menopausal age followed by no significant decline in post-menopausal females. Qmax values increased with voided volume until 700 cc followed by a plateau and decline. Conclusions: Qmax values more significantly correlated with age and voided volume than Qavg. Nomograms were drawn in centile form to provide normal reference ranges. Qmax values in our population were lower than described in literature. Patients with voided volume up to 50 ml could be evaluated with a nomogram. PMID:19955668

Hybrid Stochastic Forecasting Model for Management of Large Open Water Reservoir with Storage Function

NASA Astrophysics Data System (ADS)

Kozel, Tomas; Stary, Milos

2017-12-01

The main advantage of stochastic forecasting is fan of possible value whose deterministic method of forecasting could not give us. Future development of random process is described better by stochastic then deterministic forecasting. Discharge in measurement profile could be categorized as random process. Content of article is construction and application of forecasting model for managed large open water reservoir with supply function. Model is based on neural networks (NS) and zone models, which forecasting values of average monthly flow from inputs values of average monthly flow, learned neural network and random numbers. Part of data was sorted to one moving zone. The zone is created around last measurement average monthly flow. Matrix of correlation was assembled only from data belonging to zone. The model was compiled for forecast of 1 to 12 month with using backward month flows (NS inputs) from 2 to 11 months for model construction. Data was got ridded of asymmetry with help of Box-Cox rule (Box, Cox, 1964), value r was found by optimization. In next step were data transform to standard normal distribution. The data were with monthly step and forecast is not recurring. 90 years long real flow series was used for compile of the model. First 75 years were used for calibration of model (matrix input-output relationship), last 15 years were used only for validation. Outputs of model were compared with real flow series. For comparison between real flow series (100% successfully of forecast) and forecasts, was used application to management of artificially made reservoir. Course of water reservoir management using Genetic algorithm (GE) + real flow series was compared with Fuzzy model (Fuzzy) + forecast made by Moving zone model. During evaluation process was founding the best size of zone. Results show that the highest number of input did not give the best results and ideal size of zone is in interval from 25 to 35, when course of management was almost same for all numbers from interval. Resulted course of management was compared with course, which was obtained from using GE + real flow series. Comparing results showed that fuzzy model with forecasted values has been able to manage main malfunction and artificially disorders made by model were founded essential, after values of water volume during management were evaluated. Forecasting model in combination with fuzzy model provide very good results in management of water reservoir with storage function and can be recommended for this purpose.

Selenium mass balance in the Great Salt Lake, Utah

USGS Publications Warehouse

Diaz, X.; Johnson, W.P.; Naftz, D.L.

2009-01-01

A mass balance for Se in the south arm of the Great Salt Lake was developed for September 2006 to August 2007 of monitoring for Se loads and removal flows. The combined removal flows (sedimentation and volatilization) totaled to a geometric mean value of 2079??kg Se/yr, with the estimated low value being 1255??kg Se/yr, and an estimated high value of 3143??kg Se/yr at the 68% confidence level. The total (particulates + dissolved) loads (via runoff) were about 1560??kg Se/yr, for which the error is expected to be ?? 15% for the measured loads. Comparison of volatilization to sedimentation flux demonstrates that volatilization rather than sedimentation is likely the major mechanism of selenium removal from the Great Salt Lake. The measured loss flows balance (within the range of uncertainties), and possibly surpass, the measured annual loads. Concentration histories were modeled using a simple mass balance, which indicated that no significant change in Se concentration was expected during the period of study. Surprisingly, the measured total Se concentration increased during the period of the study, indicating that the removal processes operate at their low estimated rates, and/or there are unmeasured selenium loads entering the lake. The selenium concentration trajectories were compared to those of other trace metals to assess the significance of selenium concentration trends. ?? 2008 Elsevier B.V.

Correcting for the echo-time effect after measuring the cerebral blood flow by arterial spin labeling.

PubMed

Foucher, Jack R; Roquet, Daniel; Marrer, Corinne; Pham, Bich-Thuy; Gounot, Daniel

2011-10-01

To take into account the echo time (TE) influence on arterial spin labeling (ASL) signal when converting it in regional cerebral blood flow (rCBF). Gray matter ASL signal decrease with increasing TE as a consequence of the difference in the apparent transverse relaxation rates between labeled water in capillaries and nonlabeled water in the tissue (δR 2*). We aimed to measure ASL/rCBF changes in different parts of the brain and correct them. Fifteen participants underwent ASL measurements at TEs of 9.7-30 ms. Decreases in ASL values were localized by statistical parametric mapping. The corrections assessed were a subject-per-subject adjustment, an average δR 2* value adjustment, and a two-compartment model adjustment. rCBF decreases associated with increasing TEs were found for gray matter and were corrected using an average δR 2* value of 20 s(-1) . Conversely, for white matter, rCBF values increased with increasing TEs (δR 2* = -23 s(-1)). Our correction was as good as using a two-compartment model. However, it must be done separately for the gray and white matter rCBF values because the capillary R 2* values are, respectively, larger and smaller than those of surrounding tissues. Copyright © 2011 Wiley-Liss, Inc.

Operational evaluation of a proppeller test stand in the quiet flow facility at Langley Research Center

NASA Technical Reports Server (NTRS)

Block, P. J. W.

1982-01-01

Operational proof tests of a propeller test stand (PTS) in a quiet flow facility (QFF) are presented. The PTS is an experimental test bed for acoustic propeller research in the quiet flow environment of the QFF. These proof tests validate thrust and torque predictions, examine the repeatability of measurements on the PTS, and determine the effect of applying artificial roughness to the propeller blades. Since a thrusting propeller causes an open jet to contract, the potential flow core was surveyed to examine the magnitude of the contraction. These measurements are compared with predicted values. The predictions are used to determine operational limitations for testing a given propeller design in the QFF.

Mean velocities and Reynolds stresses in a juncture flow

NASA Technical Reports Server (NTRS)

Mcmahon, H.; Hubbartt, J.; Kubendran, L.

1982-01-01

Values of three mean velocity components and six turbulence stresses measured in a juncture flow are presented and discussed. The juncture flow is generated by a constant thickness body, having an elliptical leading edge, which is mounted perpendicular to a large flat plate along which a turbulent boundary layer is growing. The measurements were carried out at two streamwise stations in the juncture and were made using two single sensor hot-wire probes. The secondary flow in the juncture results in a considerable distortion in the mean velocity profiles. The secondary flow also transports turbulence in the juncture flow and has a large effect on the turbulence stresses. From visual inspection of the results, there is considerable evidence of similarity between the turbulent shear stresses and the mean flow strain rates. There is some evidence of similarity between the variations in the turbulent stress components.

Quantitative colorectal cancer perfusion measurement using dynamic contrast-enhanced multidetector-row computed tomography: effect of acquisition time and implications for protocols.

PubMed

Goh, Vicky; Halligan, Steve; Hugill, Jo-Ann; Gartner, Louise; Bartram, Clive I

2005-01-01

To determine the effect of acquisition time on quantitative colorectal cancer perfusion measurement. Dynamic contrast-enhanced computed tomography (CT) was performed prospectively in 10 patients with histologically proven colorectal cancer using 4-detector row CT (Lightspeed Plus; GE Healthcare Technologies, Waukesha, WI). Tumor blood flow, blood volume, mean transit time, and permeability were assessed for 3 acquisition times (45, 65, and 130 seconds). Mean values for all 4 perfusion parameters for each acquisition time were compared using the paired t test. Significant differences in permeability values were noted between acquisitions of 45 seconds and 65 and 130 seconds, respectively (P=0.02, P=0.007). There was no significant difference for values of blood volume, blood flow, and mean transit time between any of the acquisition times. Scan acquisitions of 45 seconds are too short for reliable permeability measurement in the abdomen. Longer acquisition times are required.

Simple graph models of information spread in finite populations

PubMed Central

Voorhees, Burton; Ryder, Bergerud

2015-01-01

We consider several classes of simple graphs as potential models for information diffusion in a structured population. These include biases cycles, dual circular flows, partial bipartite graphs and what we call ‘single-link’ graphs. In addition to fixation probabilities, we study structure parameters for these graphs, including eigenvalues of the Laplacian, conductances, communicability and expected hitting times. In several cases, values of these parameters are related, most strongly so for partial bipartite graphs. A measure of directional bias in cycles and circular flows arises from the non-zero eigenvalues of the antisymmetric part of the Laplacian and another measure is found for cycles as the value of the transition probability for which hitting times going in either direction of the cycle are equal. A generalization of circular flow graphs is used to illustrate the possibility of tuning edge weights to match pre-specified values for graph parameters; in particular, we show that generalizations of circular flows can be tuned to have fixation probabilities equal to the Moran probability for a complete graph by tuning vertex temperature profiles. Finally, single-link graphs are introduced as an example of a graph involving a bottleneck in the connection between two components and these are compared to the partial bipartite graphs. PMID:26064661

Local blood flow in peripheral nerves and their ganglia: Resurrecting key ideas around its measurement and significance.

PubMed

Zochodne, Douglas W

2018-06-01

Over 3 decades ago, seminal work by Phillip Low and colleagues established exquisite physiology around the measurement of nerve blood flow (NBF). Although not widely explored recently, its connection to the clinic has awaited human methodology. While human studies have not achieved a convincing level of rigour, newer imaging technologies are offering early information. The peripheral nerve trunk has parallel blood flow compartments that include epineurial flow dominated by arteriovenous shunts and downstream endoneurial blood flow (EBF). NBF and EBF have lower values than central nervous system blood flow, lack autoregulation yet have sympathetic and peptidergic neurovascular control. Contrary to expectation, injury to nerves is often associated with rises in NBF rather than ischemia, a finding of biological interest corroborated by human studies. Despite its potential importance, quantitative human measurements of EBF and NBF are not yet available. However, with development, careful NBF analysis may present new insights into nerve disorders. Muscle Nerve 57: 884-895, 2018. © 2017 Wiley Periodicals, Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bamberger, Judith A.; Piepel, Gregory F.; Enderlin, Carl W.

Understanding how uncertainty manifests itself in complex experiments is important for developing the testing protocol and interpreting the experimental results. This paper describes experimental and measurement uncertainties, and how they can depend on the order of performing experimental tests. Experiments with pulse-jet mixers in tanks at three scales were conducted to characterize the performance of transient-developing periodic flows in Newtonian slurries. Other test parameters included the simulant, solids concentration, and nozzle exit velocity. Critical suspension velocity and cloud height were the metrics used to characterize Newtonian slurry flow associated with mobilization and mixing. During testing, near-replicate and near-repeat tests weremore » conducted. The experimental results were used to quantify the combined experimental and measurement uncertainties using standard deviations and percent relative standard deviations (%RSD) The uncertainties in critical suspension velocity and cloud height tend to increase with the values of these responses. Hence, the %RSD values are the more appropriate summary measure of near-replicate testing and measurement uncertainty.« less

Comparison of five portable peak flow meters

PubMed Central

Takara, Glaucia Nency; Ruas, Gualberto; Pessoa, Bruna Varanda; Jamami, Luciana Kawakami; Di Lorenzo, Valéria Amorim Pires; Jamami, Mauricio

2010-01-01

OBJECTIVE To compare the measurements of spirometric peak expiratory flow (PEF) from five different PEF meters and to determine if their values are in agreement. Inaccurate equipment may result in incorrect diagnoses of asthma and inappropriate treatments. METHODS Sixty-eight healthy, sedentary and insufficiently active subjects, aged from 19 to 40 years, performed PEF measurements using Air Zone®, Assess®, Galemed®, Personal Best® and Vitalograph® peak flow meters. The highest value recorded for each subject for each device was compared to the corresponding spirometric values using Friedman’s test with Dunn’s post-hoc (p<0.05), Spearman’s correlation test and Bland-Altman’s agreement test. RESULTS The median and interquartile ranges for the spirometric values and the Air Zone®, Assess®, Galemed®, Personal Best® and Vitalograph® meters were 428 (263–688 L/min), 450 (350–800 L/min), 420 (310–720 L/min), 380 (300–735 L/min), 400 (310–685 L/min) and 415 (335–610 L/min), respectively. Significant differences were found when the spirometric values were compared to those recorded by the Air Zone® (p<0.001) and Galemed ® (p<0.01) meters. There was no agreement between the spirometric values and the five PEF meters. CONCLUSIONS The results suggest that the values recorded from Galemed® meters may underestimate the actual value, which could lead to unnecessary interventions, and that Air Zone® meters overestimate spirometric values, which could obfuscate the need for intervention. These findings must be taken into account when interpreting both devices’ results in younger people. These differences should also be considered when directly comparing values from different types of PEF meters. PMID:20535364

Use of radars to monitor stream discharge by noncontact methods

USGS Publications Warehouse

Costa, J.E.; Cheng, R.T.; Haeni, F.P.; Melcher, N.; Spicer, K.R.; Hayes, E.; Plant, W.; Hayes, K.; Teague, C.; Barrick, D.

2006-01-01

Conventional measurements of river flows are costly, time‐consuming, and frequently dangerous. This report evaluates the use of a continuous wave microwave radar, a monostatic UHF Doppler radar, a pulsed Doppler microwave radar, and a ground‐penetrating radar to measure river flows continuously over long periods and without touching the water with any instruments. The experiments duplicate the flow records from conventional stream gauging stations on the San Joaquin River in California and the Cowlitz River in Washington. The purpose of the experiments was to directly measure the parameters necessary to compute flow: surface velocity (converted to mean velocity) and cross‐sectional area, thereby avoiding the uncertainty, complexity, and cost of maintaining rating curves. River channel cross sections were measured by ground‐penetrating radar suspended above the river. River surface water velocity was obtained by Bragg scattering of microwave and UHF Doppler radars, and the surface velocity data were converted to mean velocity on the basis of detailed velocity profiles measured by current meters and hydroacoustic instruments. Experiments using these radars to acquire a continuous record of flow were conducted for 4 weeks on the San Joaquin River and for 16 weeks on the Cowlitz River. At the San Joaquin River the radar noncontact measurements produced discharges more than 20% higher than the other independent measurements in the early part of the experiment. After the first 3 days, the noncontact radar discharge measurements were within 5% of the rating values. On the Cowlitz River at Castle Rock, correlation coefficients between the USGS stream gauging station rating curve discharge and discharge computed from three different Doppler radar systems and GPR data over the 16 week experiment were 0.883, 0.969, and 0.992. Noncontact radar results were within a few percent of discharge values obtained by gauging station, current meter, and hydroacoustic methods. Time series of surface velocity obtained by different radars in the Cowlitz River experiment also show small‐amplitude pulsations not found in stage records that reflect tidal energy at the gauging station. Noncontact discharge measurements made during a flood on 30 January 2004 agreed with the rated discharge to within 5%. Measurement at both field sites confirm that lognormal velocity profiles exist for a wide range of flows in these rivers, and mean velocity is approximately 0.85 times measured surface velocity. Noncontact methods of flow measurement appear to (1) be as accurate as conventional methods, (2) obtain data when standard contact methods are dangerous or cannot be obtained, and (3) provide insight into flow dynamics not available from detailed stage records alone.

Design and evaluation of a miniature laser speckle imaging device to assess gingival health

PubMed Central

Regan, Caitlin; White, Sean M.; Yang, Bruce Y.; Takesh, Thair; Ho, Jessica; Wink, Cherie; Wilder-Smith, Petra; Choi, Bernard

2016-01-01

Abstract. Current methods used to assess gingivitis are qualitative and subjective. We hypothesized that gingival perfusion measurements could provide a quantitative metric of disease severity. We constructed a compact laser speckle imaging (LSI) system that could be mounted in custom-made oral molds. Rigid fixation of the LSI system in the oral cavity enabled measurement of blood flow in the gingiva. In vitro validation performed in controlled flow phantoms demonstrated that the compact LSI system had comparable accuracy and linearity compared to a conventional bench-top LSI setup. In vivo validation demonstrated that the compact LSI system was capable of measuring expected blood flow dynamics during a standard postocclusive reactive hyperemia and that the compact LSI system could be used to measure gingival blood flow repeatedly without significant variation in measured blood flow values (p<0.05). Finally, compact LSI system measurements were collected from the interdental papilla of nine subjects and compared to a clinical assessment of gingival bleeding on probing. A statistically significant correlation (ρ=0.53; p<0.005) was found between these variables, indicating that quantitative gingival perfusion measurements performed using our system may aid in the diagnosis and prognosis of periodontal disease. PMID:27787545

Design and evaluation of a miniature laser speckle imaging device to assess gingival health

NASA Astrophysics Data System (ADS)

Regan, Caitlin; White, Sean M.; Yang, Bruce Y.; Takesh, Thair; Ho, Jessica; Wink, Cherie; Wilder-Smith, Petra; Choi, Bernard

2016-10-01

Current methods used to assess gingivitis are qualitative and subjective. We hypothesized that gingival perfusion measurements could provide a quantitative metric of disease severity. We constructed a compact laser speckle imaging (LSI) system that could be mounted in custom-made oral molds. Rigid fixation of the LSI system in the oral cavity enabled measurement of blood flow in the gingiva. In vitro validation performed in controlled flow phantoms demonstrated that the compact LSI system had comparable accuracy and linearity compared to a conventional bench-top LSI setup. In vivo validation demonstrated that the compact LSI system was capable of measuring expected blood flow dynamics during a standard postocclusive reactive hyperemia and that the compact LSI system could be used to measure gingival blood flow repeatedly without significant variation in measured blood flow values (p<0.05). Finally, compact LSI system measurements were collected from the interdental papilla of nine subjects and compared to a clinical assessment of gingival bleeding on probing. A statistically significant correlation (ρ=0.53 p<0.005) was found between these variables, indicating that quantitative gingival perfusion measurements performed using our system may aid in the diagnosis and prognosis of periodontal disease.

Aero-thermal investigation of a highly loaded transonic linear turbine guide vane cascade. A test case for inviscid and viscous flow computations

NASA Astrophysics Data System (ADS)

Arts, T.; Lambertderouvroit, M.; Rutherford, A. W.

1990-09-01

An experimental aerothermal investigation of a highly loaded transonic turbine nozzle guide vane mounted in a linear cascade arrangement is presented. The measurements were performed in a short duration isentropic light piston compression tube facility, allowing a correct simulation of Mach and Reynolds numbers as well as of the gas to wall temperature ratio compared to the values currently observed in modern aeroengines. The experimental program consisted of the following: (1) flow periodicity checks by means of wall static pressure measurements and Schlieren flow visualizations; (2) blade velocity distribution measurements by means of static pressure tappings; (3) blade convective heat transfer measurements by means of static pressure tappings; (4) blade convective heat transfer measurements by means of platinium thin films; (5) downstream loss coefficient and exit flow angle determinations by using a new fast traversing mechanism; and (6) free stream turbulence intensity and spectrum measurements. These different measurements were performed for several combinations of the free stream flow parameters looking at the relative effects on the aerodynamic blade performance and blade convective heat transfer of Mach number, Reynolds number, and freestream turbulence intensity.

Vacuum-bag-only processing of composites

NASA Astrophysics Data System (ADS)

Thomas, Shad

Ultrasonic imaging in the C-scan mode in conjunction with the amplitude of the reflected signal was used to measure flow rates of an epoxy resin film penetrating through the thickness of single layers of woven carbon fabric. Assemblies, comprised of a single layer of fabric and film, were vacuum-bagged and ultrasonically scanned in a water tank during impregnation at 50°C, 60°C, 70°C, and 80°C. Measured flow rates were plotted versus inverse viscosity to determine the permeability in the thin film, non-saturated system. The results demonstrated that ultrasonic imaging in the C-scan mode is an effective method of measuring z-direction resin flow through a single layer of fabric. The permeability values determined in this work were consistent with permeability values reported in the literature. Capillary flow was not observed at the temperatures and times required for pressurized flow to occur. The flow rate at 65°C was predicted from the linear plot of flow rate versus inverse viscosity. The effects of fabric architecture on through-thickness flow rates during impregnation of an epoxy resin film were measured by ultrasonic imaging. Multilayered laminates comprised of woven carbon fabrics and epoxy films (prepregs) were fabricated by vacuum-bagging. Ultrasonic imaging was performed in a heated water tank (65°C) during impregnation. Impregnation rates showed a strong dependence on fabric architecture, despite similar areal densities. Impregnation rates are directly affected by inter-tow spacing and tow nesting, which depend on fabric architecture, and are indirectly affected by areal densities. A new method of predicting resin infusion rates in prepreg and resin film infusion processes was proposed. The Stokes equation was used to derive an equation to predict the impregnation rate of laminates as a function of fabric architecture. Flow rate data previously measured by ultrasound was analyzed with the new equation and the Kozeny-Carman equation. A fiber interaction parameter was determined as a function of fabric architecture. The derived equation is straight-forward to use, unlike the Kozeny-Carman equation. The results demonstrated that the newly derived equation can be used to predict the resin infusion rate of multilayer laminates.

Present-day heat flow model of Mars

PubMed Central

Parro, Laura M.; Jiménez-Díaz, Alberto; Mansilla, Federico; Ruiz, Javier

2017-01-01

Until the acquisition of in-situ measurements, the study of the present-day heat flow of Mars must rely on indirect methods, mainly based on the relation between the thermal state of the lithosphere and its mechanical strength, or on theoretical models of internal evolution. Here, we present a first-order global model for the present-day surface heat flow for Mars, based on the radiogenic heat production of the crust and mantle, on scaling of heat flow variations arising from crustal thickness and topography variations, and on the heat flow derived from the effective elastic thickness of the lithosphere beneath the North Polar Region. Our preferred model finds heat flows varying between 14 and 25 mW m−2, with an average value of 19 mW m−2. Similar results (although about ten percent higher) are obtained if we use heat flow based on the lithospheric strength of the South Polar Region. Moreover, expressing our results in terms of the Urey ratio (the ratio between total internal heat production and total heat loss through the surface), we estimate values close to 0.7–0.75, which indicates a moderate contribution of secular cooling to the heat flow of Mars (consistent with the low heat flow values deduced from lithosphere strength), unless heat-producing elements abundances for Mars are subchondritic. PMID:28367996

A note on drillhole depths required for reliable heat flow determinations

USGS Publications Warehouse

Chapman, D.S.; Howell, J.; Sass, J.H.

1984-01-01

In general, there is a limiting depth in a drillhole above which the reliability of a single determination of heat flow decreases rapidly with decreasing depth and below which the statistical uncertainty of a heat flow determination does not change perceptibly with increasing depth. This feature has been established empirically for a test case comprising a group of twelve heat flow sites in the Republic of Zambia. The technique consists of constructing heat flow versus depth curves for individual sites by progressively discarding data from the lower part of the hole and recomputing heat flow from the remaining data. For the Zambian test case, the curves converge towards a uniform value of 67 ?? 3 mW m-2 when all available data are used, but values of heat flow calculated for shallow(< 100 m) parts of the same holes range from 45 to 95 mW m-2. The heat flow versus depth curves are enclosed by a perturbation envelope which has an amplitude of 40 mW m-2 at the surface and decreases linearly to the noise level at 190 m. For the test region of Zambia a depth of 170 m is needed to guarantee a heat flow measurement within ?? 10% of the background regional value. It is reasonable to expect that this depth will be shallower in some regions and deeper in others. Features of heat flow perturbation envelopes can be used as quantitative reliability indices for heat flow studies. ?? 1984.

40 CFR 87.64 - Sampling and analytical procedures for measuring gaseous exhaust emissions.

Code of Federal Regulations, 2012 CFR

2012-07-01

.../kilonewton rO. (c) Report CO2 by calculation from fuel mass flow rate measurements in Appendices 3 and 5 to... 1, 2011, report CO2 values along with your emission levels of regulated NOX to the Administrator for... on or after January 1, 2011. By January 1, 2011, report CO2 values along with your emission levels of...

Theoretical and Experimental Investigation of Random Gust Loads Part I : Aerodynamic Transfer Function of a Simple Wing Configuration in Incompressible Flow

NASA Technical Reports Server (NTRS)

Hakkinen, Raimo J; Richardson, A S , Jr

1957-01-01

Sinusoidally oscillating downwash and lift produced on a simple rigid airfoil were measured and compared with calculated values. Statistically stationary random downwash and the corresponding lift on a simple rigid airfoil were also measured and the transfer functions between their power spectra determined. The random experimental values are compared with theoretically approximated values. Limitations of the experimental technique and the need for more extensive experimental data are discussed.

Quantitative blood flow measurements in the small animal cardiopulmonary system using digital subtraction angiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin Mingde; Marshall, Craig T.; Qi, Yi

Purpose: The use of preclinical rodent models of disease continues to grow because these models help elucidate pathogenic mechanisms and provide robust test beds for drug development. Among the major anatomic and physiologic indicators of disease progression and genetic or drug modification of responses are measurements of blood vessel caliber and flow. Moreover, cardiopulmonary blood flow is a critical indicator of gas exchange. Current methods of measuring cardiopulmonary blood flow suffer from some or all of the following limitations--they produce relative values, are limited to global measurements, do not provide vasculature visualization, are not able to measure acute changes, aremore » invasive, or require euthanasia. Methods: In this study, high-spatial and high-temporal resolution x-ray digital subtraction angiography (DSA) was used to obtain vasculature visualization, quantitative blood flow in absolute metrics (ml/min instead of arbitrary units or velocity), and relative blood volume dynamics from discrete regions of interest on a pixel-by-pixel basis (100x100 {mu}m{sup 2}). Results: A series of calibrations linked the DSA flow measurements to standard physiological measurement using thermodilution and Fick's method for cardiac output (CO), which in eight anesthetized Fischer-344 rats was found to be 37.0{+-}5.1 ml/min. Phantom experiments were conducted to calibrate the radiographic density to vessel thickness, allowing a link of DSA cardiac output measurements to cardiopulmonary blood flow measurements in discrete regions of interest. The scaling factor linking relative DSA cardiac output measurements to the Fick's absolute measurements was found to be 18.90xCO{sub DSA}=CO{sub Fick}. Conclusions: This calibrated DSA approach allows repeated simultaneous visualization of vasculature and measurement of blood flow dynamics on a regional level in the living rat.« less

Local Flow Conditions for Propulsion Experiments on the NASA F-15B Propulsion Flight Test Fixture

NASA Technical Reports Server (NTRS)

Vachon, Michael J.; Moes, Timothy R.; Corda, Stephen

2005-01-01

Local flow conditions were measured underneath the National Aeronautics and Space Administration F-15B airplane to support development of future experiments on the Propulsion Flight Test Fixture (PFTF). The local Mach number and flow angles were measured using a conventional air data boom on a cone-cylinder mounted under the PFTF and compared with the airplane air data nose boom measurements. At subsonic flight speeds, the airplane and PFTF Mach numbers were approximately equal. Transonic Mach number values were up to 0.1 greater at the PFTF than the airplane, which is a counterintuitive result. The PFTF local supersonic Mach numbers were as much as 0.46 less than the airplane values. The maximum local Mach number at the PFTF was approximately 1.6 at an airplane Mach number near 2.0. The PFTF local angle of attack was negative at all Mach numbers, ranging from -3 to -8 degrees. When the airplane angle of sideslip was zero, the PFTF local value was zero between Mach 0.8 and Mach 1.1, -2 degrees between Mach 1.1 and Mach 1.5, and increased from zero to 1 degree from Mach 1.5 to Mach 2.0. Airplane inlet shock waves crossed the aerodynamic interface plane between Mach 1.85 and Mach 1.90.

[Digital blood flow measurement by venous occlusion plethysmography in Raynaud's phenomenon. Value of the rewarming test].

PubMed

Cristol, R; Debray, J

1986-01-01

The fingertip blood flow measured by mercury strain gauge plethysmography with venous occlusion, at 22 degrees C room temperature, had significantly lower mean values in 190 patients with Raynaud's phenomenon (55 men aged 49 yrs +/- 16, 135 women aged 48 yrs +/- 16) than in 40 age and sex matched controls: 18 ml/100 ml/minute +/- 14.6 versus 35 ml/100 ml/minute +/- 15 at level p less than 0.01. The mean fingertip blood flow was significantly lower (p less than 0.01) in 31 cases of scleroderma and 32 cases of pulpar necrosis (respectively 13 ml +/- 13 and 11 ml +/- 8) than in 55 cases of primary Raynaud's disease (no detectable etiology and normal capillaroscopy 5 years after onset) or in 34 cases of mild Raynaud's phenomenon (respectively 21.6 +/- 16 and 24.4 +/- 18). A warming test (both hands in water at 45 degrees C during 3 minutes) was performed in 50 cases with low basal fingertip blood flow. It induced a "normalized" flow in 22 cases (mostly primary or mild Raynaud), a partly improved flow in 20 cases (mostly secondary Raynaud) and no improvement in 8 cases (scleroderma). The warming test appears to be clinically useful to assess the vasospasm and the vasodilating capabilities.

Flow fields behind a variable-area nozzle for radial turbines

NASA Astrophysics Data System (ADS)

Hayami, Hiroshi; Hyun, Yong-Ik; Senoo, Yasutoshi; Yamaguchi, Michiteru

The flow fields behind a variable-area nozzle for radial turbines were measured in detail using a three-hole cobra probe in 15 cases, which are a combination of three nozzle throat areas (0.8, 1.0, and 1.4 times the rated area) and five values of the tip-clearance to blade-height ratio (between 0.0 to 0.099). The flow fields at different tip clearances are presented in contour maps, and the pitch mean values are discussed as spanwise distributions of total pressure loss, flow angle, and radial and tangential velocity components. It is shown that the intensity of swirl behind the nozzle is decreased and the pressure loss is increased with the tip clearance, and the effect is magnified as the blade loading is higher.

A stepwise model to predict monthly streamflow

NASA Astrophysics Data System (ADS)

Mahmood Al-Juboori, Anas; Guven, Aytac

2016-12-01

In this study, a stepwise model empowered with genetic programming is developed to predict the monthly flows of Hurman River in Turkey and Diyalah and Lesser Zab Rivers in Iraq. The model divides the monthly flow data to twelve intervals representing the number of months in a year. The flow of a month, t is considered as a function of the antecedent month's flow (t - 1) and it is predicted by multiplying the antecedent monthly flow by a constant value called K. The optimum value of K is obtained by a stepwise procedure which employs Gene Expression Programming (GEP) and Nonlinear Generalized Reduced Gradient Optimization (NGRGO) as alternative to traditional nonlinear regression technique. The degree of determination and root mean squared error are used to evaluate the performance of the proposed models. The results of the proposed model are compared with the conventional Markovian and Auto Regressive Integrated Moving Average (ARIMA) models based on observed monthly flow data. The comparison results based on five different statistic measures show that the proposed stepwise model performed better than Markovian model and ARIMA model. The R2 values of the proposed model range between 0.81 and 0.92 for the three rivers in this study.

Correlation between voluntary cough and laryngeal cough reflex flows in patients with traumatic brain injury.

PubMed

Lee, Sang Chul; Kang, Seong-Woong; Kim, Min Tae; Kim, Yong Kyun; Chang, Won Hyuk; Im, Sang Hee

2013-08-01

To correlate voluntary cough and laryngeal cough reflex (LCR) flows in patients with traumatic brain injury (TBI). Cross-sectional study. University rehabilitation hospital. Patients with TBI (n=25) and healthy controls (n=48). Not applicable. Peak cough flows (PCFs) and LCR flows were measured using a peak flow meter at the oral-nasal interface. The largest value of 3 attempts was recorded for PCF and LCR, respectively. LCR was elicited by 20% solution of pharmaceutic-grade citric acid dissolved in sterile .15M NaCl solution that was inhaled from a nebulizer. PCF was 447.4 ± 99.0 L/min in the control group and 211.7 ± 58.2 L/min in the patient group. LCR was 209.2 ± 63.8L/min in the control group and 170.0 ± 59.7 L/min in the patient group. Both PCF (P=.000) and LCR (P=.013) were significantly reduced in patients with TBI compared to that of the control group. LCR was strongly related to the PCF in both control (R=.645; P=.000) and patient (R=.711; P=.000) groups. As LCR can be measured as a numerical value and significantly correlates with PCF, LCR can be used to estimate cough ability of patients with TBI who cannot cooperate with PCF measurement. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

A comparison of quality of present-day heat flow obtained from BHTs, Horner Plots of Malay Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waples, D.W.; Mahadir, R.

1994-07-01

Reconciling temperature data obtained from measurement of single BHT, multiple BHT at a single depth, RFTs, and DSTs, is very difficult. Quality of data varied widely, however DST data were assumed to be most reliable. Data from 87 wells was used in this study, but only 47 wells have DST data. BASINMOD program was used to calculate the present-day heat flow, using measured thermal conductivity and calibrated against the DST data. The heat flows obtained from the DST data were assumed to be correct and representative throughout the basin. Then, heat flows using (1) uncorrected RFT data, (2) multiple BHTmore » data corrected by the Horner plot method, and (3) single BHT values corrected upward by a standard 10% were calculated. All of these three heat-flow populations had identically standard deviations to that for the DST data, but with significantly lower mean values. Correction factors were calculated to give each of the three erroneous populations the same mean value as the DST population. Heat flows calculated from RFT data had to be corrected upward by a factor of 1.12 to be equivalent to DST data; Horner plot data corrected by a factor of 1.18, and single BHT data by a factor of 1.2. These results suggest that present-day subsurface temperatures using RFT, Horner plot, and BHT data are considerably lower than they should be. The authors suspect qualitatively similar results would be found in other areas. Hence, they recommend significant corrections be routinely made until local calibration factors are established.« less

Analysis of the dynamics of venous blood flow in the context of lower limb temperature distribution and tissue composition in the elderly.

PubMed

Skomudek, Aleksandra; Gilowska, Iwona; Jasiński, Ryszard; Rożek-Piechura, Krystyna

2017-01-01

The elderly are particularly vulnerable to degenerative diseases, such as circulatory and respiratory system and vascular system diseases. The objective of this study was therefore to evaluate the distribution of temperature and the dynamics of venous blood flow in the lower limbs (LLs) and to assess the interdependence of these parameters in terms of the somatic components in males and females participating in activities at the University of the Third Age. The study included 60 females (mean age 67.4 years) and 40 males (mean age 67.5 years). A body composition assessment was performed using the bioimpedance technique - Tanita BC-418MA. The following parameters were examined: fat%, fat mass, fat-free mass, and total body water. The minimal, maximal, and mean temperature values and their distributions were examined using infrared thermographic camera VarioCAM Head. Measurements of the venous refilling time and the work of the LL venous pump were examined using a Rheo Dopplex II PPG. In males, the mean value of the right LL temperature was 30.58 and the mean value of the left LL was 30.28; the P -value was 0.805769. In females, the mean value of the right LL temperature was 29.58 and the mean value of the left limb was 29.52; the P -value was 0.864773. In males, the right limb blood flow was 34.17 and the left limb blood flow was 34.67; the P -value was 0.359137. In females, the right limb blood flow was 26.89 and the left limb blood flow was 26.09; the P -value was 0.796348. Research results showed that the temperature distribution and the dynamics of blood flow are not significantly different between the right and left extremities in both males and females. However, significant temperature differences were found between the gender groups. Significantly higher temperature values in both the right and left extremities were recorded in males than in females.

A NEW PRINCIPLE FOR ELECTROMAGNETIC CATHETER FLOW METERS*

PubMed Central

Kolin, Alexander

1969-01-01

An electromagnetic catheter flow meter is described in which the magnetic field is generated by two parallel bundles of wire carrying equal currents in opposite directions. The electrodes are fixed centrally to the insulated wire bundles that generate the magnetic field. The flow sensor is flexible, resembling a split catheter. The flow transducer is designed to constrict as it is introduced through a branch artery and to expand in the main artery over the span of its diameter. The principle is suitable for branch flow measurement as well as for measurement of flow in a major artery or vein by the same transducer. A special method of guiding the electrode wires results in a zero base line at zero flow for the entire range of diameters accommodating the field generating coil. The electrodes could be used in this configuration with a magnetic field generated by coils external to the patient for blood flow measurements with a catheter of reduced gauge. The transducer can be made smaller in circumference than those employed in other electromagnetic flow measuring catheter devices. This feature is of special value for envisaged clinical uses (percutaneous introduction) to minimize surgical intervention. The velocity sensitivity of the flow transducer is a logarithmic function of the tube diameter. The flow throughout the entire tube cross section contributes to the flow signal. It is sufficient to calibrate the transducer by one measurement in a dielectric conduit of less than maximum diameter. The sensitivity at other diameters follows from a logarithmic plot. The diameter of the blood vessel is outlined by the transducer in radiograms, thus obviating the need for radiopaque materials. The principle was demonstrated by measurements in vitro. Experiments in vivo, derivation of equations, and construction details will be published elsewhere. Images PMID:5257127

Low-flow characteristics of streams in Virginia

USGS Publications Warehouse

Hayes, Donald C.

1991-01-01

Streamflow data were collected and low-flow characteristics computed for 715 gaged sites in Virginia Annual minimum average 7-consecutive-day flows range from 0 to 2,195 cubic feet per second for a 2-year recurrence interval and from 0 to 1,423 cubic feet per second for a 10-year recurrence interval. Drainage areas range from 0.17 to 7,320 square miles. Existing and discontinued gaged sites are separated into three types: long-term continuous-record sites, short-term continuous-record sites, and partial-record sites. Low-flow characteristics for long-term continuous-record sites are determined from frequency curves of annual minimum average 7-consecutive-day flows . Low-flow characteristics for short-term continuous-record sites are estimated by relating daily mean base-flow discharge values at a short-term site to concurrent daily mean discharge values at nearby long-term continuous-record sites having similar basin characteristics . Low-flow characteristics for partial-record sites are estimated by relating base-flow measurements to daily mean discharge values at long-term continuous-record sites. Information from the continuous-record sites and partial-record sites in Virginia are used to develop two techniques for estimating low-flow characteristics at ungaged sites. A flow-routing method is developed to estimate low-flow values at ungaged sites on gaged streams. Regional regression equations are developed for estimating low-flow values at ungaged sites on ungaged streams. The flow-routing method consists of transferring low-flow characteristics from a gaged site, either upstream or downstream, to a desired ungaged site. A simple drainage-area proration is used to transfer values when there are no major tributaries between the gaged and ungaged sites. Standard errors of estimate for108 test sites are 19 percent of the mean for estimates of low-flow characteristics having a 2-year recurrence interval and 52 percent of the mean for estimates of low-flow characteristics having a 10-year recurrence interval . A more complex transfer method must be used when major tributaries enter the stream between the gaged and ungaged sites. Twenty-four stream networks are analyzed, and predictions are made for 84 sites. Standard errors of estimate are 15 percent of the mean for estimates of low-flow characteristics having a 2-year recurrence interval and 22 percent of the mean for estimates of low-flow characteristics having a 10-year recurrence interval. Regional regression equations were developed for estimating low-flow values at ungaged sites on ungaged streams. The State was divided into eight regions on the basis of physiography and geographic grouping of the residuals computed in regression analyses . Basin characteristics that were significant in the regression analysis were drainage area, rock type, and strip-mined area. Standard errors of prediction range from 60 to139 percent for estimates of low-flow characteristics having a 2-year recurrence interval and 90 percent to 172 percent for estimates of low-flow characteristics having a 10-year recurrence interval.

Predictive Value of Reactive Hyperemia for Cardiovascular Events in Patients With Peripheral Arterial Disease Undergoing Vascular Surgery

PubMed Central

Huang, Alex L.; Silver, Annemarie E.; Shvenke, Elena; Schopfer, David W.; Jahangir, Eiman; Titas, Megan A.; Shpilman, Alex; Menzoian, James O.; Watkins, Michael T.; Raffetto, Joseph D.; Gibbons, Gary; Woodson, Jonathan; Shaw, Palma M.; Dhadly, Mandeep; Eberhardt, Robert T.; Keaney, John F.; Gokce, Noyan; Vita, Joseph A.

2008-01-01

Objective Reactive hyperemia is the compensatory increase in blood flow that occurs after a period of tissue ischemia, and this response is blunted in patients with cardiovascular risk factors. The predictive value of reactive hyperemia for cardiovascular events in patients with atherosclerosis and the relative importance of reactive hyperemia compared with other measures of vascular function have not been previously studied. Methods and Results We prospectively measured reactive hyperemia and brachial artery flow-mediated dilation by ultrasound in 267 patients with peripheral arterial disease referred for vascular surgery (age 66±11 years, 26% female). Median follow-up was 309 days (range 1 to 730 days). Fifty patients (19%) had an event, including cardiac death (15), myocardial infarction (18), unstable angina (8), congestive heart failure (6), and nonhemorrhagic stroke (3). Patients with an event were older and had lower hyperemic flow velocity (75±39 versus 95±50 cm/s, P=0.009). Patients with an event also had lower flow-mediated dilation (4.5±3.0 versus 6.9±4.6%, P<0.001), and when these 2 measures of vascular function were included in the same Cox proportional hazards model, lower hyperemic flow (OR 2.7, 95% CI 1.2 to 5.9, P=0.018) and lower flow-mediated dilation (OR 4.2, 95% CI: 1.8 to 9.8, P=0.001) both predicted cardiovascular events while adjusting for other risk factors. Conclusions Thus, lower reactive hyperemia is associated with increased cardiovascular risk in patients with peripheral arterial disease. Furthermore, flow-mediated dilation and reactive hyperemia incrementally relate to cardiovascular risk, although impaired flow-mediated dilation was the stronger predictor in this population. These findings further support the clinical relevance of vascular function measured in the microvasculature and conduit arteries in the upper extremity. PMID:17717291

Surface flow observations from a gauge-cam station on the Tiber river

NASA Astrophysics Data System (ADS)

Tauro, Flavia; Porfiri, Maurizio; Petroselli, Andrea; Grimaldi, Salvatore

2016-04-01

Understanding the kinematic organization of natural water bodies is central to hydrology and environmental engineering practice. Reliable and continuous flow observations are essential to comprehend flood generation and propagation mechanisms, erosion dynamics, sediment transport, and drainage network evolution. In engineering practice, flood warning systems largely rely on real-time discharge measurements, and flow velocity monitoring is important for the design and management of hydraulic structures, such as reservoirs and hydropower plants. Traditionally, gauging stations have been equipped with water level meters, and stage-discharge relationships (rating curves) have been established through few direct discharge measurements. Only in rare instances, monitoring stations have integrated radar technology for local measurement of surface flow velocity. Establishing accurate rating curves depends on the availability of a comprehensive range of discharge values, including measurements recorded during extreme events. However, discharge values during high-flow events are often difficult or even impossible to obtain, thereby hampering the reliability of discharge predictions. Fully remote observations have been enabled in the past ten years through optics-based velocimetry techniques. Such methodologies enable the estimation of the surface flow velocity field over extended regions from the motion of naturally occurring debris or floaters dragged by the current. Resting on the potential demonstrated by such approaches, here, we present a novel permanent gauge-cam station for the observation of the flow velocity field in the Tiber river. This new station captures one-minute videos every 10 minutes over an area of up to 20.6 × 15.5m2. In a feasibility study, we demonstrate that experimental images analyzed via particle tracking velocimetry and particle image velocimetry can be used to obtain accurate surface flow velocity estimations in close agreement with radar records. Future efforts will be devoted to the development of a comprehensive testbed infrastructure for investigating the potential of multiple optics-based approaches for surface hydrology.

TDLAS-based sensors for in situ measurement of syngas composition in a pressurized, oxygen-blown, entrained flow coal gasifier

NASA Astrophysics Data System (ADS)

Sur, Ritobrata; Sun, Kai; Jeffries, Jay B.; Hanson, Ronald K.; Pummill, Randy J.; Waind, Travis; Wagner, David R.; Whitty, Kevin J.

2014-07-01

Tunable diode laser absorption spectroscopy based in situ sensors for CO (2.33 μm), CO2 (2.02 μm), CH4 (2.29 μm) and H2O (1.35 μm) were deployed in a pilot-scale (1 ton/day), high-pressure (up to 18 atm), entrained flow, oxygen-blown, slagging coal gasifier at the University of Utah. Measurements of species mole fraction with 3-s time resolution were taken at the pre- and post-filtration stages of the gasifier synthesis gas (called here syngas) output flow. Although particulate scattering makes pre-filter measurements more difficult, this location avoids the time delay of flow through the filtration devices. With the measured species and known N2 concentrations, the H2 content was obtained via balance. The lower heating value and the Wobbe index of the gas mixture were estimated using the measured gas composition. The sensors demonstrated here show promise for monitoring and control of the gasification process.

40 CFR 1065.205 - Performance specifications for measurement instruments.

Code of Federal Regulations, 2014 CFR

2014-07-01

... are all determined with the same collected data, as described in § 1065.305, and based on absolute... meters to allow noise to be measured at the lowest calibrated value instead of zero flow rate. [79 FR...

Follicle vascularity coordinates corpus luteum blood flow and progesterone production.

PubMed

de Tarso, S G S; Gastal, G D A; Bashir, S T; Gastal, M O; Apgar, G A; Gastal, E L

2017-03-01

Colour Doppler ultrasonography was used to compare the ability of preovulatory follicle (POF) blood flow and its dimensions to predict the size, blood flow and progesterone production capability of the subsequent corpus luteum (CL). Cows (n=30) were submitted to a synchronisation protocol. Follicles ≥7mm were measured and follicular wall blood flow evaluated every 12h for approximately 3.5 days until ovulation. After ovulation, cows were scanned daily for 8 days and similar parameters were evaluated for the CL. Blood samples were collected and plasma progesterone concentrations quantified. All parameters were positively correlated. Correlation values ranged from 0.26 to 0.74 on data normalised to ovulation and from 0.31 to 0.74 on data normalised to maximum values. Correlations between calculated ratios of both POF and CL in data normalised to ovulation and to maximum values ranged from moderate (0.57) to strong (0.87). Significant (P<0.0001) linear regression analyses were seen in all comparisons. In conclusion, higher correlations were observed between the dimensions of POF and/or CL and blood flow of both structures, as well as POF and/or CL blood flow with plasma progesterone concentrations of the resultant CL. These findings indicate that follicle vascularity coordinates CL blood flow and progesterone production in synchronised beef cows.

Blood flow quantification using 1D CFD parameter identification

NASA Astrophysics Data System (ADS)

Brosig, Richard; Kowarschik, Markus; Maday, Peter; Katouzian, Amin; Demirci, Stefanie; Navab, Nassir

2014-03-01

Patient-specific measurements of cerebral blood flow provide valuable diagnostic information concerning cerebrovascular diseases rather than visually driven qualitative evaluation. In this paper, we present a quantitative method to estimate blood flow parameters with high temporal resolution from digital subtraction angiography (DSA) image sequences. Using a 3D DSA dataset and a 2D+t DSA sequence, the proposed algorithm employs a 1D Computational Fluid Dynamics (CFD) model for estimation of time-dependent flow values along a cerebral vessel, combined with an additional Advection Diffusion Equation (ADE) for contrast agent propagation. The CFD system, followed by the ADE, is solved with a finite volume approximation, which ensures the conservation of mass. Instead of defining a new imaging protocol to obtain relevant data, our cost function optimizes the bolus arrival time (BAT) of the contrast agent in 2D+t DSA sequences. The visual determination of BAT is common clinical practice and can be easily derived from and be compared to values, generated by a 1D-CFD simulation. Using this strategy, we ensure that our proposed method fits best to clinical practice and does not require any changes to the medical work flow. Synthetic experiments show that the recovered flow estimates match the ground truth values with less than 12% error in the mean flow rates.

Non-invasive pulmonary blood flow analysis and blood pressure mapping derived from 4D flow MRI

NASA Astrophysics Data System (ADS)

Delles, Michael; Rengier, Fabian; Azad, Yoo-Jin; Bodenstedt, Sebastian; von Tengg-Kobligk, Hendrik; Ley, Sebastian; Unterhinninghofen, Roland; Kauczor, Hans-Ulrich; Dillmann, Rüdiger

2015-03-01

In diagnostics and therapy control of cardiovascular diseases, detailed knowledge about the patient-specific behavior of blood flow and pressure can be essential. The only method capable of measuring complete time-resolved three-dimensional vector fields of the blood flow velocities is velocity-encoded magnetic resonance imaging (MRI), often denoted as 4D flow MRI. Furthermore, relative pressure maps can be computed from this data source, as presented by different groups in recent years. Hence, analysis of blood flow and pressure using 4D flow MRI can be a valuable technique in management of cardiovascular diseases. In order to perform these tasks, all necessary steps in the corresponding process chain can be carried out in our in-house developed software framework MEDIFRAME. In this article, we apply MEDIFRAME for a study of hemodynamics in the pulmonary arteries of five healthy volunteers. The study included measuring vector fields of blood flow velocities by phase-contrast MRI and subsequently computing relative blood pressure maps. We visualized blood flow by streamline depictions and computed characteristic values for the left and the right pulmonary artery (LPA and RPA). In all volunteers, we observed a lower amount of blood flow in the LPA compared to the RPA. Furthermore, we visualized blood pressure maps using volume rendering and generated graphs of pressure differences between the LPA, the RPA and the main pulmonary artery. In most volunteers, blood pressure was increased near to the bifurcation and in the proximal LPA, leading to higher average pressure values in the LPA compared to the RPA.

40 CFR 65.160 - Performance test and TRE index value determination records.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the control device, the total regeneration stream mass flow during each carbon-bed regeneration cycle... each regeneration during the period of the performance test (and within 15 minutes of completion of any... the recovery system, the total regeneration stream mass flow measured at least every 15 minutes and...

40 CFR 65.160 - Performance test and TRE index value determination records.

Code of Federal Regulations, 2012 CFR

2012-07-01

... the control device, the total regeneration stream mass flow during each carbon-bed regeneration cycle... each regeneration during the period of the performance test (and within 15 minutes of completion of any... the recovery system, the total regeneration stream mass flow measured at least every 15 minutes and...

40 CFR 65.160 - Performance test and TRE index value determination records.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the control device, the total regeneration stream mass flow during each carbon-bed regeneration cycle... each regeneration during the period of the performance test (and within 15 minutes of completion of any... the recovery system, the total regeneration stream mass flow measured at least every 15 minutes and...

40 CFR 65.160 - Performance test and TRE index value determination records.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the control device, the total regeneration stream mass flow during each carbon-bed regeneration cycle... each regeneration during the period of the performance test (and within 15 minutes of completion of any... the recovery system, the total regeneration stream mass flow measured at least every 15 minutes and...

Opposed-flow flame spread and extinction in mixed-convection boundary layers

NASA Technical Reports Server (NTRS)

Altenkirch, R. A.; Wedha-Nayagam, M.

1989-01-01

Experimental data for flame spread down thin fuel samples in an opposing, mixed-convection, boundary-layer flow are analyzed to determine the gas-phase velocity that characterizes how the flame reacts as it spreads toward the leading edge of the fuel sample into a thinning boundary layer. In the forced-flow limit where the cube of the Reynolds number divided by the Grashof number, Re exp 3/Gr, is large, L(q)/L(e), where L(q) is a theoretical flame standoff distance at extinction and L(e) is the measured distance from the leading edge of the sample where extinction occurs, is found to be proportional to Re exp n with n = -0.874 and Re based on L(e). The value of n is established by the character of the flow field near the leading edge of the flame. The Re dependence is used, along with a correction for the mixed-convection situation where Re exp 3/Gr is not large, to construct a Damkohler number with which the measured spread rates correlate for all values of Re exp 3/Gr.

Can we Relate Basal Ice Mechanics to Seismic Observations of the Bed?

NASA Astrophysics Data System (ADS)

Kyrke-Smith, T.; Gudmundsson, G. H.; Farrell, P. E.

2017-12-01

We compare results from two different methods of quanitfying basal ice conditions, by investigating correlations between seismically-derived estimates of basal acoustic impedance and basal slipperiness values obtained from a surface-to-bed inversion of a Stokes ice flow model. Using high-resolution measurements taken along several seismic profiles on Pine Island Glacier (PIG), we find no correlation between acoustic impedance and retrieved basal slipperiness wihtin each individual profile. However, there is a correlation when comparing averaged values across each distinct profile. Nevertheless, there is no clear way of incorporating seismic measurements of bed properties on ice streams into ice flow models. We conclude that more theoretical work needs done before constraints on mechanical conditions at the ice-bed interface from acoustic impedance measurements can be of direct use to ice sheet models.

A comparison of airborne wake vortex detection measurements with values predicted from potential theory

NASA Technical Reports Server (NTRS)

Stewart, Eric C.

1991-01-01

An analysis of flight measurements made near a wake vortex was conducted to explore the feasibility of providing a pilot with useful wake avoidance information. The measurements were made with relatively low cost flow and motion sensors on a light airplane flying near the wake vortex of a turboprop airplane weighing approximately 90000 lbs. Algorithms were developed which removed the response of the airplane to control inputs from the total airplane response and produced parameters which were due solely to the flow field of the vortex. These parameters were compared with values predicted by potential theory. The results indicated that the presence of the vortex could be detected by a combination of parameters derived from the simple sensors. However, the location and strength of the vortex cannot be determined without additional and more accurate sensors.

Concentration Measurements in a Cold Flow Model Annular Combustor Using Laser Induced Fluorescence

NASA Technical Reports Server (NTRS)

Morgan, Douglas C.

1996-01-01

A nonintrusive concentration measurement method is developed for determining the concentration distribution in a complex flow field. The measurement method consists of marking a liquid flow with a water soluble fluorescent dye. The dye is excited by a two dimensional sheet of laser light. The fluorescent intensity is shown to be proportional to the relative concentration level. The fluorescent field is recorded on a video cassette recorder through a video camera. The recorded images are analyzed with image processing hardware and software to obtain intensity levels. Mean and root mean square (rms) values are calculated from these intensity levels. The method is tested on a single round turbulent jet because previous concentration measurements have been made on this configuration by other investigators. The previous results were used to comparison to qualify the current method. These comparisons showed that this method provides satisfactory results. 'Me concentration measurement system was used to measure the concentrations in the complex flow field of a model gas turbine annular combustor. The model annular combustor consists of opposing primary jets and an annular jet which discharges perpendicular to the primary jets. The mixing between the different jet flows can be visualized from the calculated mean and rms profiles. Concentration field visualization images obtained from the processing provide further qualitative information about the flow field.

Application of Manning's Formula for Estimation of Liquid Metal Levels in Electromagnetic Flow Measurements

NASA Astrophysics Data System (ADS)

Stelian, Carmen

2015-02-01

Lorentz force velocimetry is a new technique in electromagnetic flow measurements based on exposing an electrical conducting metal to a static magnetic field and measuring the force acting on the magnet system. The calibration procedure of a Lorentz force flowmeter used in industrial open-channel flow measurements is difficult because of the fluctuating liquid level in the channel. In this paper, the application of Manning's formula to estimate the depth of a liquid metal flowing in an open channel is analyzed by using the numerical modeling. Estimations of Manning's n parameter for aluminum show higher values as compared with water flowing in artificial channels. Saint-Venant equations are solved in order to analyze the wave propagation at the free surface of the liquid. Numerical results show a significant damping of waves at the surface of liquid metals as compared with water. Therefore, the Manning formula can be used to correlate the liquid depth and the flow rate in LFF numerical calibration procedure. These results show that the classical formulas, used exclusively to study the water flow in open channels, can be also applied for the liquid metals. The application of Manning's formulas requires experimental measurements of the parameter n, which depends on the channel bed roughness and also on the physical properties of the liquid flowing in channel.

Emerging interdependence between stock values during financial crashes.

PubMed

Rocchi, Jacopo; Tsui, Enoch Yan Lok; Saad, David

2017-01-01

To identify emerging interdependencies between traded stocks we investigate the behavior of the stocks of FTSE 100 companies in the period 2000-2015, by looking at daily stock values. Exploiting the power of information theoretical measures to extract direct influences between multiple time series, we compute the information flow across stock values to identify several different regimes. While small information flows is detected in most of the period, a dramatically different situation occurs in the proximity of global financial crises, where stock values exhibit strong and substantial interdependence for a prolonged period. This behavior is consistent with what one would generally expect from a complex system near criticality in physical systems, showing the long lasting effects of crashes on stock markets.

Emerging interdependence between stock values during financial crashes

PubMed Central

Tsui, Enoch Yan Lok; Saad, David

2017-01-01

To identify emerging interdependencies between traded stocks we investigate the behavior of the stocks of FTSE 100 companies in the period 2000-2015, by looking at daily stock values. Exploiting the power of information theoretical measures to extract direct influences between multiple time series, we compute the information flow across stock values to identify several different regimes. While small information flows is detected in most of the period, a dramatically different situation occurs in the proximity of global financial crises, where stock values exhibit strong and substantial interdependence for a prolonged period. This behavior is consistent with what one would generally expect from a complex system near criticality in physical systems, showing the long lasting effects of crashes on stock markets. PMID:28542278

On the evolution of the geothermal regime of the North China Basin

NASA Astrophysics Data System (ADS)

Wang, Ji-yang; Chen, Mo-xiang; Wang, Ji-an; Deng, Xiao

1985-12-01

Recent heat flow and regional geothermal studies indicate that the North China Basin is characterized by relatively high heat flow compared with most stable areas in other parts of the world, but lower heat flow than most active tectonic areas. Measured heat flow values range from 61 to 74 mW m -2. The temperature at a depth of 2000 m is generally in the range 75 to 85°C, but sometimes is 90°C or higher. The geothermal gradient in Cenozoic sediments is in the range 30 to 40°C/km for most of the area. The calculated temperature at the Moho is 560 and 640°C for surface heat flow values of 63 and 71 mW m -2, respectively. These thermal data are consistent with other geophysical observations for the North China Basin. Relatively high heat flow in this area is related to Late Cretaceous-Paleogene rifting as described in this paper.

Nonlinear Reynolds stress model for turbulent shear flows

NASA Technical Reports Server (NTRS)

Barton, J. Michael; Rubinstein, R.; Kirtley, K. R.

1991-01-01

A nonlinear algebraic Reynolds stress model, derived using the renormalization group, is applied to equilibrium homogeneous shear flow and fully developed flow in a square duct. The model, which is quadratically nonlinear in the velocity gradients, successfully captures the large-scale inhomogeneity and anisotropy of the flows studied. The ratios of normal stresses, as well as the actual magnitudes of the stresses are correctly predicted for equilibrium homogeneous shear flow. Reynolds normal stress anisotropy and attendant turbulence driven secondary flow are predicted for a square duct. Profiles of mean velocity and normal stresses are in good agreement with measurements. Very close to walls, agreement with measurements diminishes. The model has the benefit of containing no arbitrary constants; all values are determined directly from the theory. It seems that near wall behavior is influenced by more than the large scale anisotropy accommodated in the current model. More accurate near wall calculations may well require a model for anisotropic dissipation.

The feasibility of recharge rate determinations using the steady- state centrifuge method

USGS Publications Warehouse

Nimmo, J.R.; Stonestrom, David A.; Akstin, K.C.

1994-01-01

The establishment of steady unsaturated flow in a centrifuge permits accurate measurement of small values of hydraulic conductivity (K). This method can provide a recharge determination if it is applied to an unsaturated core sample from a depth at which gravity alone drives the flow. A K value determined at the in situ water content indicates the long-term average recharge rate at a point. Tests of this approach have been made at two sites. For sandy core samples a better knowledge of the matric pressure profiles is required before a recharge rate can be determined. Fine-textured cores required new developments of apparatus and procedures, especially for making centrifuge measurements with minimal compaction of the samples. -from Authors

Retrospective cost adaptive Reynolds-averaged Navier-Stokes k-ω model for data-driven unsteady turbulent simulations

NASA Astrophysics Data System (ADS)

Li, Zhiyong; Hoagg, Jesse B.; Martin, Alexandre; Bailey, Sean C. C.

2018-03-01

This paper presents a data-driven computational model for simulating unsteady turbulent flows, where sparse measurement data is available. The model uses the retrospective cost adaptation (RCA) algorithm to automatically adjust the closure coefficients of the Reynolds-averaged Navier-Stokes (RANS) k- ω turbulence equations to improve agreement between the simulated flow and the measurements. The RCA-RANS k- ω model is verified for steady flow using a pipe-flow test case and for unsteady flow using a surface-mounted-cube test case. Measurements used for adaptation of the verification cases are obtained from baseline simulations with known closure coefficients. These verification test cases demonstrate that the RCA-RANS k- ω model can successfully adapt the closure coefficients to improve agreement between the simulated flow field and a set of sparse flow-field measurements. Furthermore, the RCA-RANS k- ω model improves agreement between the simulated flow and the baseline flow at locations at which measurements do not exist. The RCA-RANS k- ω model is also validated with experimental data from 2 test cases: steady pipe flow, and unsteady flow past a square cylinder. In both test cases, the adaptation improves agreement with experimental data in comparison to the results from a non-adaptive RANS k- ω model that uses the standard values of the k- ω closure coefficients. For the steady pipe flow, adaptation is driven by mean stream-wise velocity measurements at 24 locations along the pipe radius. The RCA-RANS k- ω model reduces the average velocity error at these locations by over 35%. For the unsteady flow over a square cylinder, adaptation is driven by time-varying surface pressure measurements at 2 locations on the square cylinder. The RCA-RANS k- ω model reduces the average surface-pressure error at these locations by 88.8%.

Influence of nitric oxide-mediated vasodilation on the blood pressure measured with the tail-cuff method in the rat.

PubMed

Fritz, Mariana; Rinaldi, Gustavo

2007-11-01

Systolic blood pressure (SBP) is frequently measured in rats by the tail cuff method, which usually comprises pulse/flow disappearance and reappearance during cuff inflation (Inf) and deflation (Def), separated by an interval between cycles (IBC). Although Def values are habitually used to estimate SBP, in 58 Wistar rats we found (Def-Inf) to be -6 +/- 1 mmHg, indicating that Def < Inf in most cases. When the IBC was lengthened to 2 min, (Def-Inf) was increased to -17 +/- 2 mmHg, indicating the probable accumulation of a vasodilating metabolite. This increase of (Def-Inf) was prevented by papaverine, indicating its relation to smooth muscle contractility. Adrenergic blockade did not prevent the increase of (Def-Inf), but pretreatment with L-NAME decreased it to -5 +/- 2 mmHg (p < 0.05). Simultaneous measurement of SBP by tail-cuff method and carotid cannulation revealed that the Inf value was the most accurate estimation of intravascular SBP. We conclude that: (1) the Inf value should be taken as representative of SBP, since depending on the duration of suprasystolic compression the Def value can underestimate it, and (2) nitric oxide accumulation due to flow deprivation was the main cause of SBP underestimation by Def values.

Label-Free, Flow-Imaging Methods for Determination of Cell Concentration and Viability.

PubMed

Sediq, A S; Klem, R; Nejadnik, M R; Meij, P; Jiskoot, Wim

2018-05-30

To investigate the potential of two flow imaging microscopy (FIM) techniques (Micro-Flow Imaging (MFI) and FlowCAM) to determine total cell concentration and cell viability. B-lineage acute lymphoblastic leukemia (B-ALL) cells of 2 different donors were exposed to ambient conditions. Samples were taken at different days and measured with MFI, FlowCAM, hemocytometry and automated cell counting. Dead and live cells from a fresh B-ALL cell suspension were fractionated by flow cytometry in order to derive software filters based on morphological parameters of separate cell populations with MFI and FlowCAM. The filter sets were used to assess cell viability in the measured samples. All techniques gave fairly similar cell concentration values over the whole incubation period. MFI showed to be superior with respect to precision, whereas FlowCAM provided particle images with a higher resolution. Moreover, both FIM methods were able to provide similar results for cell viability as the conventional methods (hemocytometry and automated cell counting). FIM-based methods may be advantageous over conventional cell methods for determining total cell concentration and cell viability, as FIM measures much larger sample volumes, does not require labeling, is less laborious and provides images of individual cells.

Changes in scalp and cortical blood flow during hyperventilation measured with diffusing-wave spectroscopy

NASA Astrophysics Data System (ADS)

Li, Jun; Ninck, Markus; Gisler, Thomas

2009-07-01

Changes in scalp and cortical blood flow induced by voluntary hyperventilation are investigated by near-infrared diffusing-wave spectroscopy. The temporal intensity autocorrelation function g(2) (τ) of multiply scattered light is recorded from the forehead of subjects during hyperventilation. Blood flow within the sampled tissue volume is estimated by the mean decay rate of g(2) (τ) . Data measured from six subjects show that the pattern of the hemodynamic response during 50 s hyperventilation is rather complicated: within the first 10 s, in three subjects an initial increase in blood flow is observed; from 10 s to 20 s, the mean blood flow is smaller than its baseline value for all six subjects; for the duration from 20 s to 30 s, the blood flow increases again. However, after 30 s the change is not consistent across subjects. Further study on one of these subjects by using two receivers probing the blood flow in the cortex and in the superficial layers simultaneously, reveals that during hyperventilation, the direction of change in blood flow within the scalp is opposite to the one in the brain. This helps to understand the complicated hemodynamic response observed in our measurements.

Surface tension of flowing soap films

NASA Astrophysics Data System (ADS)

Sane, Aakash; Mandre, Shreyas; Kim, Ildoo

2018-04-01

The surface tension of flowing soap films is measured with respect to the film thickness and the concentration of soap solution. We perform this measurement by measuring the curvature of the nylon wires that bound the soap film channel and use the measured curvature to parametrize the relation between the surface tension and the tension of the wire. We find the surface tension of our soap films increases when the film is relatively thin or made of soap solution of low concentration, otherwise it approaches an asymptotic value 30 mN/m. A simple adsorption model with only two parameters describes our observations reasonably well. With our measurements, we are also able to measure Gibbs elasticity for our soap film.

Imposing constraints on parameter values of a conceptual hydrological model using baseflow response

NASA Astrophysics Data System (ADS)

Dunn, S. M.

Calibration of conceptual hydrological models is frequently limited by a lack of data about the area that is being studied. The result is that a broad range of parameter values can be identified that will give an equally good calibration to the available observations, usually of stream flow. The use of total stream flow can bias analyses towards interpretation of rapid runoff, whereas water quality issues are more frequently associated with low flow condition. This paper demonstrates how model distinctions between surface an sub-surface runoff can be used to define a likelihood measure based on the sub-surface (or baseflow) response. This helps to provide more information about the model behaviour, constrain the acceptable parameter sets and reduce uncertainty in streamflow prediction. A conceptual model, DIY, is applied to two contrasting catchments in Scotland, the Ythan and the Carron Valley. Parameter ranges and envelopes of prediction are identified using criteria based on total flow efficiency, baseflow efficiency and combined efficiencies. The individual parameter ranges derived using the combined efficiency measures still cover relatively wide bands, but are better constrained for the Carron than the Ythan. This reflects the fact that hydrological behaviour in the Carron is dominated by a much flashier surface response than in the Ythan. Hence, the total flow efficiency is more strongly controlled by surface runoff in the Carron and there is a greater contrast with the baseflow efficiency. Comparisons of the predictions using different efficiency measures for the Ythan also suggest that there is a danger of confusing parameter uncertainties with data and model error, if inadequate likelihood measures are defined.

Integration of Quantitative Positron Emission Tomography Absolute Myocardial Blood Flow Measurements in the Clinical Management of Coronary Artery Disease.

PubMed

Gewirtz, Henry; Dilsizian, Vasken

2016-05-31

In the >40 years since planar myocardial imaging with(43)K-potassium was introduced into clinical research and management of patients with coronary artery disease (CAD), diagnosis and treatment have undergone profound scientific and technological changes. One such innovation is the current state-of-the-art hardware and software for positron emission tomography myocardial perfusion imaging, which has advanced it from a strictly research-oriented modality to a clinically valuable tool. This review traces the evolving role of quantitative positron emission tomography measurements of myocardial blood flow in the evaluation and management of patients with CAD. It presents methodology, currently or soon to be available, that offers a paradigm shift in CAD management. Heretofore, radionuclide myocardial perfusion imaging has been primarily qualitative or at best semiquantitative in nature, assessing regional perfusion in relative terms. Thus, unlike so many facets of modern cardiovascular practice and CAD management, which depend, for example, on absolute values of key parameters such as arterial and left ventricular pressures, serum lipoprotein, and other biomarker levels, the absolute levels of rest and maximal myocardial blood flow have yet to be incorporated into routine clinical practice even in most positron emission tomography centers where the potential to do so exists. Accordingly, this review focuses on potential value added for improving clinical CAD practice by measuring the absolute level of rest and maximal myocardial blood flow. Physiological principles and imaging fundamentals necessary to understand how positron emission tomography makes robust, quantitative measurements of myocardial blood flow possible are highlighted. © 2016 American Heart Association, Inc.

Pretreatment Prediction of the Outcomes of Intranasal Steroid Sprays in Cases with Inferior Turbinate Hypertrophy.

PubMed

Karataş, Abdullah

2017-09-01

Intranasal steroid sprays (INSS) are frequently prescribed for treating inferior turbinate hypertrophy (ITH). Complications due to the long-term application of INSS such as crusting, epistaxis, nasal mucosa dryness, and septal perforation may occur. Predicting patients who would benefit from INSS early might lower treatment costs and complication rates. We examined the predictive value of nasal decongestant response rates for the outcomes of INSS in ITH. Fifty patients with bilateral ITH were included in two groups: patients benefiting from INSS and those not benefiting. Nasal airflow was assessed by peak nasal inspiratory flow (PNIF) measurement in all cases. Measurements were taken three times: before and after the application of nasal decongestant sprays and after the application of INSS. In both groups, the nasal air flow rates significantly increased after the application of nasal decongestant sprays; however, the nasal decongestant response rates were higher in the group with patients benefiting from INSS. There was a strong correlation between the nasal air flow rates measured after the application of nasal decongestant sprays and after the application of INSS. The cut-off value for the relationship between increased nasal air flow rates after the application of nasal decongestant sprays and outcomes of INSS was 23%. Measurement of nasal airflow increase rate after the application of nasal decongestant sprays is a simple and easy method for the early prediction of the outcomes of INSS in ITH. A higher than 23% increase in nasal air flow rates after the application of nasal decongestant sprays indicates much better outcomes of INSS for patients.

Pretreatment Prediction of the Outcomes of Intranasal Steroid Sprays in Cases with Inferior Turbinate Hypertrophy

PubMed Central

Karataş, Abdullah

2017-01-01

Objective Intranasal steroid sprays (INSS) are frequently prescribed for treating inferior turbinate hypertrophy (ITH). Complications due to the long-term application of INSS such as crusting, epistaxis, nasal mucosa dryness, and septal perforation may occur. Predicting patients who would benefit from INSS early might lower treatment costs and complication rates. We examined the predictive value of nasal decongestant response rates for the outcomes of INSS in ITH. Methods Fifty patients with bilateral ITH were included in two groups: patients benefiting from INSS and those not benefiting. Nasal airflow was assessed by peak nasal inspiratory flow (PNIF) measurement in all cases. Measurements were taken three times: before and after the application of nasal decongestant sprays and after the application of INSS. Results In both groups, the nasal air flow rates significantly increased after the application of nasal decongestant sprays; however, the nasal decongestant response rates were higher in the group with patients benefiting from INSS. There was a strong correlation between the nasal air flow rates measured after the application of nasal decongestant sprays and after the application of INSS. The cut-off value for the relationship between increased nasal air flow rates after the application of nasal decongestant sprays and outcomes of INSS was 23%. Conclusion Measurement of nasal airflow increase rate after the application of nasal decongestant sprays is a simple and easy method for the early prediction of the outcomes of INSS in ITH. A higher than 23% increase in nasal air flow rates after the application of nasal decongestant sprays indicates much better outcomes of INSS for patients. PMID:29392066

Sequence optimization to reduce velocity offsets in cardiovascular magnetic resonance volume flow quantification - A multi-vendor study

PubMed Central

2011-01-01

Purpose Eddy current induced velocity offsets are of concern for accuracy in cardiovascular magnetic resonance (CMR) volume flow quantification. However, currently known theoretical aspects of eddy current behavior have not led to effective guidelines for the optimization of flow quantification sequences. This study is aimed at identifying correlations between protocol parameters and the resulting velocity error in clinical CMR flow measurements in a multi-vendor study. Methods Nine 1.5T scanners of three different types/vendors were studied. Measurements were performed on a large stationary phantom. Starting from a clinical breath-hold flow protocol, several protocol parameters were varied. Acquisitions were made in three clinically relevant orientations. Additionally, a time delay between the bipolar gradient and read-out, asymmetric versus symmetric velocity encoding, and gradient amplitude and slew rate were studied in adapted sequences as exploratory measurements beyond the protocol. Image analysis determined the worst-case offset for a typical great-vessel flow measurement. Results The results showed a great variation in offset behavior among scanners (standard deviation among samples of 0.3, 0.4, and 0.9 cm/s for the three different scanner types), even for small changes in the protocol. Considering the absolute values, none of the tested protocol settings consistently reduced the velocity offsets below the critical level of 0.6 cm/s neither for all three orientations nor for all three scanner types. Using multilevel linear model analysis, oblique aortic and pulmonary slices showed systematic higher offsets than the transverse aortic slices (oblique aortic 0.6 cm/s, and pulmonary 1.8 cm/s higher than transverse aortic). The exploratory measurements beyond the protocol yielded some new leads for further sequence development towards reduction of velocity offsets; however those protocols were not always compatible with the time-constraints of breath-hold imaging and flow-related artefacts. Conclusions This study showed that with current systems there was no generic protocol which resulted into acceptable flow offset values. Protocol optimization would have to be performed on a per scanner and per protocol basis. Proper optimization might make accurate (transverse) aortic flow quantification possible for most scanners. Pulmonary flow quantification would still need further (offline) correction. PMID:21388521

Inland notches micromorphology

NASA Astrophysics Data System (ADS)

Brook, Anna; Ben-Binyamin, Atzmon; Shtober-Zisu, Nurit

2017-04-01

Inland notches are well known phenomenon in Israel and can be found mostly along the mountainous backbone, developed in hard limestone or dolomite rocks within the Mediterranean climate zone and up to the desert fringe. LiDAR technology presents an opportunity to study the fine scale rock surface within the notch and its texture patterns. De-trending of the LiDAR reconstructed DEM to a local trend, surface roughness, was achieved by fitting a normalized surface to all measured ground points within the roughness neighborhood. Micro-topography plays an important role for modelling geomorphology dynamics, resulting in improved estimates for micro stream lines network and topographic erosion as well as mineral accumulation or deposition. Clearly, dissolution occurs whenever rock and solvent meet; thus water and moisture's crucial role in the decay of carbonate rocks results in texture and roughness variability. Study aims is to generate high resolution normalized DEM models using a terrestrial LiDAR, redefining the texture and roughness within the notch while assessing weathering processes caused by water. Plan curvature is the second derivative of slope taken perpendicular to its direction. It influences convergence and divergence of flow and it emphasizes the ridges and valleys across the surface. Concaved classified areas were tested against all planar curvature areas to distinguish them as unique areas based on their texture co-occurrence measures (GLCM). Overall negative curvature pixels show poor separability, in both TD and JM separation tests, while classes of curvature degree describe a positive trend showing medium and high concavity as unique areas. Study aims to link classified areas as the basic micro infrastructure for water flow, potential runoff flow and further accumulation of minerals. On the other hand, positive values of Plan curvature present the convexity of rock surface to imply diverging flow, thus describing the watershed line within the micro-topography. GLCM texture measure map distinct areas within the notch. Middle section of the notch has uniform texture neighborhood with relatively low mean elevation values (high values for homogeneity and energy). Bottom cavity of notch reveals a more chaotic texture, highlighting the spatial disorder with relatively high mean values. Entropy calculates how random the roughness values are, and as such, high values of this measure, at the cavity's bottom, suggest a potentially rapid erosion or disposition dynamics.

On-line measurement of heat of combustion

NASA Technical Reports Server (NTRS)

Chaturvedi, S. K.; Chegini, H.

1988-01-01

An experimental method for an on-line measurement of heat of combustion of a gaseous hydrocarbon fuel mixture of unknown composition is developed. It involves combustion of a test gas with a known quantity of air to achieve a predetermined oxygen concentration level in the combustion products. This is accomplished by a feedback controller which maintains the gas volumetric flow rate at a level consistent with the desired oxygen concentration in the products. The heat of combustion is determined from a known correlation with the gas volumetric flow rate. An on-line microcomputer accesses the gas volumetric flow data, and displays the heat of combustion values at desired time intervals.

Background-Oriented Schlieren (BOS) for Scramjet Inlet-isolator Investigation

NASA Astrophysics Data System (ADS)

Che Idris, Azam; Rashdan Saad, Mohd; Hing Lo, Kin; Kontis, Konstantinos

2018-05-01

Background-oriented Schlieren (BOS) technique is a recently invented non-intrusive flow diagnostic method which has yet to be fully explored in its capabilities. In this paper, BOS technique has been applied for investigating the general flow field characteristics inside a generic scramjet inlet-isolator with Mach 5 flow. The difficulty in finding the delicate balance between measurement sensitivity and measurement area image focusing has been demonstrated. The differences between direct cross-correlation (DCC) and Fast Fourier Transform (FFT) raw data processing algorithm have also been demonstrated. As an exploratory study of BOS capability, this paper found that BOS is simple yet robust enough to be used to visualize complex flow in a scramjet inlet in hypersonic flow. However, in this case its quantitative data can be strongly affected by 3-dimensionality thus obscuring the density value with significant errors.

Visualizing dissolved oxygen transport for liquid ventilation in an in vitro model of the human airways

NASA Astrophysics Data System (ADS)

Janke, T.; Bauer, K.

2017-04-01

Up until to now, the measurement of dissolved oxygen concentrations during liquid ventilation is limited to the determination of averaged concentrations of the liquid entering or leaving the body. The work presented in this paper aims to extend the possible measurement techniques in the research of liquid ventilation. Therefore optical measurements of the dissolved oxygen concentration, using a luminescent sensor dye, are performed. The preparation of a suitable sensor liquid, based on the metal complex Dichlorotris(1,10)-(phenanthroline)ruthenium(II), is presented. A transparent simplified human lung geometry is used for conducting the experiments. Inspiratory as well as expiratory flow at three different constant flow rates is investigated, covering the flow regimes \\text{Re}=83 -333 and \\text{Pe}=33 300 -133 000. The applied measurement technique is capable to reveal distinctive concentration patterns during inspiration and expiration caused by the laminar flow characteristics. Allowing a sufficiently long flow duration, local concentration inhomogeneities disappear and an exponential rise and decay of the mean values can be observed for inspiration and expiration.

Calorimetry of 25 Ah lithium/thionyl chloride cells

NASA Technical Reports Server (NTRS)

Johnson, C. J.; Dawson, S.

1991-01-01

Heat flow measurements of 25-Ah lithium thionyl chloride cells provided a method to calculate an effective thermal potential, E(TP) of 3.907 V. The calculation is useful to determine specific heat generation of this cell chemistry and design. The E(TP) value includes heat generation by electrochemical cell reactions, competitive chemical reactions, and resistance heating at the tabs, connectors, and leads. Heat flow was measured while applying electrical loads to the cell in an isothermal calorimeter set at 0, 20, and 60 C.

TOXICITY OF ACETYLENIC ALCOHOLS TO THE FATHEAD MINNOW, PIMEPHALES PROMELAS: NARCOSIS AND PROELECTROPHILE ACTIVATION

EPA Science Inventory

The 96-h LC50 values for 16 acetylenic alcohols in the fathead minnow (Pimephales promelas) were determined using continuous-flow diluters. The measured LC50 values for seven tertiary propargylic alcohols agreed closely with the QSAR predictions based upon data for other organic ...

Heat transfer, pressure drop and flow patterns during flow boiling of R407C in a horizontal microfin tube

NASA Astrophysics Data System (ADS)

Rollmann, P.; Spindler, K.; Müller-Steinhagen, H.

2011-08-01

The heat transfer, pressure drop and flow patterns during flow boiling of R407C in a horizontal microfin tube have been investigated. The microfin tube is made of copper with a total fin number of 55 and a helix angle of 15°. The fin height is 0.24 mm and the inner tube diameter at fin root is 8.95 mm. The test tube is 1 m long. It is heated electrically. The experiments have been performed at saturation temperatures between -30°C and +10°C. The mass flux was varied between 25 and 300 kg/m2/s, the heat flux from 20,000 W/m2 down to 1,000 W/m2. The vapour quality was kept constant at 0.1, 0.3, 0.5, 0.7 at the inlet and 0.8, 1.0 at the outlet, respectively. The measured heat transfer coefficient is compared with the correlations of Cavallini et al., Shah as well as Zhang et al. Cavallini's correlation contains seven experimental constants. After fitting these constants to our measured values, the correlation achieves good agreement. The measured pressure drop is compared to the correlations of Pierre, Kuo and Wang as well as Müller-Steinhagen and Heck. The best agreement is achieved with the correlation of Kuo and Wang. Almost all values are calculated within an accuracy of ±30%. The flow regimes were observed. It is shown, that changes in the flow regime affect the heat transfer coefficient significantly.

Relation of electrochemical potentials and iron content to ground-water flow patterns

USGS Publications Warehouse

Back, William; Barnes, Ivan

1965-01-01

This study was undertaken to develop means of measuring oxidation potentials in aquifer systems and to use the measured values in interpreting the behavior of iron in ground water. Anne Arundel County, Md., was selected as the area of study because of the wide range of concentration of iron-nearly zero to about 35 ppm-in the ground water and the rather complete information on the geology and hydrology. The regional geology consists of coastal plain sediments ranging in age from Early Cretaceous through the Recent. Most of the pH and oxidation-potential measurements were made in nonmarine Cretaceous deposits, only a few in the marine Eocene. Iron-bearing minerals in the area are primarily hematite or limonite and glauconite with a small amount of pyrite. Equipment was developed that permits the measurement of oxidation potentials by use of saturated calomel and platinum electrodes in ground-water samples uncontaminated by oxygen of the atmosphere. Measured Eh values range from about +700 mv to -40 mv. Approximately 2 to 3 hours are required to measure a stable or nearly stable oxidation potential. The mineralogy and organic content of the deposits and the ground-water flow pattern are the primary controls on the oxidation potential and pH of the water. A correlation exists between the oxidation potential and the concentration of iron in ground water; the higher concentrations occur in waters with the lowest values of Eh. The concentration of iron in the water tested shows little correlation with the pH of the water. The highest oxidation potentials were measured in water produced from shallow wells and those wells in recharge areas. The lowest potentials were measured farthest downgradient in water associated with gray and green sediments. The Eh values measured in the field are between values predicted from the solubility of Fe(OH)2(c) and values predicted from the solubility of hematite.

Heat Transfer at the Reattachment Zone of Separated Laminar Boundary Layers

NASA Technical Reports Server (NTRS)

Chung, Paul M.; Viegas, John R.

1961-01-01

The flow and heat transfer are analyzed at the reattachment zone of two-dimensional separated laminar boundary layers. The fluid is considered to be flowing normal to the wall at reattachment. An approximate expression is derived for the heat transfer in the reattachment region and a calculated value is compared with an experimental measurement.

Does Arterial Spin-labeling MR Imaging–measured Tumor Perfusion Correlate with Renal Cell Cancer Response to Antiangiogenic Therapy in a Mouse Model?

PubMed Central

Schor-Bardach, Rachel; Alsop, David C.; Pedrosa, Ivan; Solazzo, Stephanie A.; Wang, Xiaoen; Marquis, Robert P.; Atkins, Michael B.; Regan, Meredith; Signoretti, Sabina; Lenkinski, Robert E.; Goldberg, S. Nahum

2009-01-01

Purpose: To determine whether arterial spin-labeling (ASL) magnetic resonance (MR) imaging findings at baseline and early during antiangiogenic therapy can predict later resistance to therapy. Materials and Methods: Protocol was approved by an institutional animal care and use committee. Caki-1, A498, and 786-0 human renal cell carcinoma (RCC) xenografts were implanted in 39 nude mice. Animals received 80 mg sorafenib per kilogram of body weight once daily once tumors measured 12 mm. ASL imaging was performed at baseline and day 14, with additional imaging performed for 786-0 and A498 (3 days to 12 weeks). Mean blood flow values and qualitative differences in spatial distribution of blood flow were analyzed and compared with histopathologic findings for viability and microvascular density. t Tests were used to compare differences in mean tumor blood flow. Bonferroni-adjusted P values less than .05 denoted significant differences. Results: Baseline blood flow was 80.1 mL/100 g/min ± 23.3 (standard deviation) for A498, 75.1 mL/100 g/min ± 28.6 for 786-0, and 10.2 mL/100 g/min ± 9.0 for Caki-1. Treated Caki-1 showed no significant change (14.9 mL/100 g/min ± 7.6) in flow, whereas flow decreased in all treated A498 on day 14 (47.9 mL/100 g/min ± 21.1) and in 786-0 on day 3 (20.3 mL/100 g/min ± 8.7) (P = .003 and .03, respectively). For A498, lowest values were measured at 28–42 days of receiving sorafenib. Regions of increased flow occurred on days 35–49, 17–32 days before documented tumor growth and before significant increases in mean flow (day 77). Although 786-0 showed new, progressive regions with signal intensity detected as early as day 5 that correlated to viable tumor at histopathologic examination, no significant changes in mean flow were noted when day 3 was compared with all subsequent days (P > .99). Conclusion: ASL imaging provides clinically relevant information regarding tumor viability in RCC lines that respond to sorafenib. © RSNA, 2009 PMID:19474376

Small-scale anisotropic intermittency in magnetohydrodynamic turbulence at low magnetic Reynolds numbers.

PubMed

Okamoto, Naoya; Yoshimatsu, Katsunori; Schneider, Kai; Farge, Marie

2014-03-01

Small-scale anisotropic intermittency is examined in three-dimensional incompressible magnetohydrodynamic turbulence subjected to a uniformly imposed magnetic field. Orthonormal wavelet analyses are applied to direct numerical simulation data at moderate Reynolds number and for different interaction parameters. The magnetic Reynolds number is sufficiently low such that the quasistatic approximation can be applied. Scale-dependent statistical measures are introduced to quantify anisotropy in terms of the flow components, either parallel or perpendicular to the imposed magnetic field, and in terms of the different directions. Moreover, the flow intermittency is shown to increase with increasing values of the interaction parameter, which is reflected in strongly growing flatness values when the scale decreases. The scale-dependent anisotropy of energy is found to be independent of scale for all considered values of the interaction parameter. The strength of the imposed magnetic field does amplify the anisotropy of the flow.

Probing Reliability of Transport Phenomena Based Heat Transfer and Fluid Flow Analysis in Autogeneous Fusion Welding Process

NASA Astrophysics Data System (ADS)

Bag, S.; de, A.

2010-09-01

The transport phenomena based heat transfer and fluid flow calculations in weld pool require a number of input parameters. Arc efficiency, effective thermal conductivity, and viscosity in weld pool are some of these parameters, values of which are rarely known and difficult to assign a priori based on the scientific principles alone. The present work reports a bi-directional three-dimensional (3-D) heat transfer and fluid flow model, which is integrated with a real number based genetic algorithm. The bi-directional feature of the integrated model allows the identification of the values of a required set of uncertain model input parameters and, next, the design of process parameters to achieve a target weld pool dimension. The computed values are validated with measured results in linear gas-tungsten-arc (GTA) weld samples. Furthermore, a novel methodology to estimate the overall reliability of the computed solutions is also presented.

Mock Circulatory System of the Fontan Circulation to Study Respiration Effects on Venous Flow Behavior

PubMed Central

Vukicevic, M.; Chiulli, J.A.; Conover, T.; Pennati, G.; Hsia, T.Y.; Figliola, R.S.

2013-01-01

We describe an in vitro model of the Fontan circulation with respiration to study subdiaphragmatic venous flow behavior. The venous and arterial connections of a total cavopulmonary connection (TCPC) test section were coupled with a physical lumped parameter (LP) model of the circulation. Intrathoracic and subdiaphragmatic pressure changes associated with normal breathing were applied. This system was tuned for two patients (5 years, 0.67 m2; 10 years, 1.2 m2) to physiological values. System function was verified by comparison to the analytical model on which it was based and by consistency with published clinical measurements. Overall, subdiaphragmatic venous flow was influenced by respiration. Flow within the arteries and veins increased during inspiration but decreased during expiration with retrograde flow in the inferior venous territories. System pressures and flows showed close agreement with the analytical LP model (p < 0.05). The ratio of the flow rates occurring during inspiration to expiration were within the clinical range of values reported elsewhere. The approach used to setup and control the model was effective and provided reasonable comparisons with clinical data. PMID:23644612

Human red blood cell behavior under homogeneous extensional flow in a hyperbolic-shaped microchannel.

PubMed

Yaginuma, T; Oliveira, M S N; Lima, R; Ishikawa, T; Yamaguchi, T

2013-01-01

It is well known that certain pathological conditions result in a decrease of red blood cells (RBCs) deformability and subsequently can significantly alter the blood flow in microcirculation, which may block capillaries and cause ischemia in the tissues. Microfluidic systems able to obtain reliable quantitative measurements of RBC deformability hold the key to understand and diagnose RBC related diseases. In this work, a microfluidic system composed of a microchannel with a hyperbolic-shaped contraction followed by a sudden expansion is presented. We provide a detailed quantitative description of the degree of deformation of human RBCs under a controlled homogeneous extensional flow field. We measured the deformation index (DI) as well as the velocity of the RBCs travelling along the centerline of the channel for four different flow rates and analyze the impact of the particle Reynolds number. The results show that human RBC deformation tends to reach a plateau value in the region of constant extensional rate, the value of which depends on the extension rate. Additionally, we observe that the presence of a sudden expansion downstream of the hyperbolic contraction modifies the spatial distribution of cells and substantially increases the cell free layer (CFL) downstream of the expansion plane similarly to what is seen in other expansion flows. Beyond a certain value of flow rate, there is only a weak effect of inlet flow rates on the enhancement of the downstream CFL. These in vitro experiments show the potential of using microfluidic systems with hyperbolic-shaped microchannels both for the separation of the RBCs from plasma and to assess changes in RBC deformability in physiological and pathological situations for clinical purposes. However, the selection of the geometry and the identification of the most suitable region to evaluate the changes on the RBC deformability under extensional flows are crucial if microfluidics is to be used as an in vitro clinical methodology to detect circulatory diseases.

Human red blood cell behavior under homogeneous extensional flow in a hyperbolic-shaped microchannel

PubMed Central

Yaginuma, T.; Oliveira, M. S. N.; Lima, R.; Ishikawa, T.; Yamaguchi, T.

2013-01-01

It is well known that certain pathological conditions result in a decrease of red blood cells (RBCs) deformability and subsequently can significantly alter the blood flow in microcirculation, which may block capillaries and cause ischemia in the tissues. Microfluidic systems able to obtain reliable quantitative measurements of RBC deformability hold the key to understand and diagnose RBC related diseases. In this work, a microfluidic system composed of a microchannel with a hyperbolic-shaped contraction followed by a sudden expansion is presented. We provide a detailed quantitative description of the degree of deformation of human RBCs under a controlled homogeneous extensional flow field. We measured the deformation index (DI) as well as the velocity of the RBCs travelling along the centerline of the channel for four different flow rates and analyze the impact of the particle Reynolds number. The results show that human RBC deformation tends to reach a plateau value in the region of constant extensional rate, the value of which depends on the extension rate. Additionally, we observe that the presence of a sudden expansion downstream of the hyperbolic contraction modifies the spatial distribution of cells and substantially increases the cell free layer (CFL) downstream of the expansion plane similarly to what is seen in other expansion flows. Beyond a certain value of flow rate, there is only a weak effect of inlet flow rates on the enhancement of the downstream CFL. These in vitro experiments show the potential of using microfluidic systems with hyperbolic-shaped microchannels both for the separation of the RBCs from plasma and to assess changes in RBC deformability in physiological and pathological situations for clinical purposes. However, the selection of the geometry and the identification of the most suitable region to evaluate the changes on the RBC deformability under extensional flows are crucial if microfluidics is to be used as an in vitro clinical methodology to detect circulatory diseases. PMID:24404073

Runoff process in the Miyake-jima Island after Eruption in 2000

NASA Astrophysics Data System (ADS)

Tagata, Satoshi; Itoh, Takahiro; Miyamoto, Kuniaki; Ishizuka, Tadanori

2014-05-01

Hydrological environment in a basin can be changed completely due to volcanic eruption. Huge volume of tephra was yielded due to eruptions in 2000 in the Miyake-jima Island, Japan. Hydrological monitoring was conducted at four observation sites with several hundred m2 in a basin. Those were decided by the distribution of thickness and the grain size of the tephra. Rainfall intensity was measured by a tipping bucket type raingauge and flow discharge was calculated by the over flow depth in a flow gauging weir in the monitoring. However, the runoff rate did not relate to the grain size of tephra and the thickness of tephra deposition, according to measured data of rainfall intensity and runoff discharge. Supposing that if total runoff in one rainfall event is equal to the summation of rainfall over a threshold, the value of the threshold must be the loss rainfall intensity, the value of the threshold corresponds to the infiltration for the rainfall intensity. The relationships between loss rainfall intensity and the antecedent precipitation are calculated using measured rainfall and runoff data in every rainfall event, focusing on that the antecedent precipitation before occurrence of surface runoff approximately corresponds to the water contents under the slope surface. In present study, the results obtained through data analyses are summarized as follows: (1) There are some values for the threshold values, and the loss rainfall intensity approaches to some constant value if the value of the antecedent precipitation increases. The constant value corresponds to the saturated infiltration. (2) The loss rainfall intensity must be vertical unsaturated infiltration, and observed data for water runoff can express that the runoff is given by the excess rainfall intensity more than the loss rainfall intensity. (3) There are two antecedent times for rainfall with several hours and several days, and the saturation ratio before antecedent time at four observation sites can be predicted in the range from sixty to ninety percentages by the water retention curve.

In vitro validation of a Pitot-based flow meter for the measurement of respiratory volume and flow in large animal anaesthesia.

PubMed

Moens, Yves P S; Gootjes, Peter; Ionita, Jean-Claude; Heinonen, Erkki; Schatzmann, Urs

2009-05-01

To remodel and validate commercially available monitors and their Pitot tube-based flow sensors for use in large animals, using in vitro techniques. Prospective, in vitro experiment. Both the original and the remodelled sensor were studied with a reference flow generator. Measurements were taken of the static flow-pressure relationship and linearity of the flow signal. Sensor airway resistance was calculated. Following recalibration of the host monitor, volumes ranging from 1 to 7 L were generated by a calibration syringe, and bias and precision of spirometric volume was determined. Where manual recalibration was not available, a conversion factor for volume measurement was determined. The influence of gas composition mixture and peak flow on the conversion factor was studied. Both the original and the remodelled sensor showed similar static flow-pressure relationships and linearity of the flow signal. Mean bias (%) of displayed values compared with the reference volume of 3, 5 and 7 L varied between -0.4% and +2.4%, and this was significantly smaller than that for 1 L (4.8% to +5.0%). Conversion factors for 3, 5 and 7 L were very similar (mean 6.00 +/- 0.2, range 5.91-6.06) and were not significantly influenced by the gas mixture used. Increasing peak flow caused a small decrease in the conversion factor. Volume measurement error and conversion factors for inspiration and expiration were close to identity. The combination of the host monitor with the remodelled flow sensor allowed accurate in vitro measurement of flows and volumes in a range expected during large animal anaesthesia. This combination has potential as a reliable spirometric monitor for use during large animal anaesthesia.

Velocity and pressure measurements in guide vane clearance gap of a low specific speed Francis turbine

NASA Astrophysics Data System (ADS)

Thapa, B. S.; Dahlhaug, O. G.; Thapa, B.

2016-11-01

In Francis turbine, a small clearance gap between the guide vanes and the cover plates is usually required to pivot guide vanes as a part of governing system. Deflection of cover plates and erosion of mating surfaces causes this gap to increase from its design value. The clearance gap induces the secondary flow in the distributor system. This effects the main flow at the runner inlet, which causes losses in efficiency and instability. A guide vane cascade of a low specific speed Francis turbine has been developed for experimental investigations. The test setup is able to produce similar velocity distributions at the runner inlet as that of a reference prototype turbine. The setup is designed for particle image velocimetry (PIV) measurements from the position of stay vane outlet to the position of runner inlet. In this study, velocity and pressure measurements are conducted with 2 mm clearance gap on one side of guide vane. Leakage flow is observed and measured together with pressure measurements. It is concluded that the leakage flow behaves as a jet and mixes with the main flow in cross-wise direction and forms a vortex filament. This causes non-uniform inlet flow conditions at runner blades.

Effects of caffeine on fractional flow reserve values measured using intravenous adenosine triphosphate.

PubMed

Nakayama, Masafumi; Chikamori, Taishiro; Uchiyama, Takashi; Kimura, Yo; Hijikata, Nobuhiro; Ito, Ryosuke; Yuhara, Mikio; Sato, Hideaki; Kobori, Yuichi; Yamashina, Akira

2018-04-01

We investigated the effects of caffeine intake on fractional flow reserve (FFR) values measured using intravenous adenosine triphosphate (ATP) before cardiac catheterization. Caffeine is a competitive antagonist for adenosine receptors; however, it is unclear whether this antagonism affects FFR values. Patients were evenly randomized into 2 groups preceding the FFR study. In the caffeine group (n = 15), participants were given coffee containing 222 mg of caffeine 2 h before the catheterization. In the non-caffeine group (n = 15), participants were instructed not to take any caffeine-containing drinks or foods for at least 12 h before the catheterization. FFR was performed in patients with more than intermediate coronary stenosis using the intravenous infusion of ATP at 140 μg/kg/min (normal dose) and 170 μg/kg/min (high dose), and the intracoronary infusion of papaverine. FFR was followed for 30 s after maximal hyperemia. In the non-caffeine group, the FFR values measured with ATP infusion were not significantly different from those measured with papaverine infusion. However, in the caffeine group, the FFR values were significantly higher after ATP infusion than after papaverine infusion (P = 0.002 and P = 0.007, at normal and high dose ATP vs. papaverine, respectively). FFR values with ATP infusion were significantly increased 30 s after maximal hyperemia (P = 0.001 and P < 0.001 for normal and high dose ATP, respectively). The stability of the FFR values using papaverine showed no significant difference between the 2 groups. Caffeine intake before the FFR study affected FFR values and their stability. These effects could not be reversed by an increased ATP dose.

Heat transfer and pressure measurements for the SSME fuel turbine

NASA Technical Reports Server (NTRS)

Dunn, Michael G.; Kim, Jungho

1991-01-01

A measurement program is underway using the Rocketdyne two-stage Space Shuttle Main Engine (SSME) fuel turbine. The measurements use a very large shock tunnel to produce a short-duration source of heated and pressurized gas which is subsequently passed through the turbine. Within this environment, the turbine is operated at the design values of flow function, stage pressure ratio, stage temperature ratio, and corrected speed. The first stage vane row and the first stage blade row are instrumented in both the spanwise and chordwise directions with pressure transducers and heat flux gages. The specific measurements to be taken include time averaged surface pressure and heat flux distributions on the vane and blade, flow passage static pressure, flow passage total pressure and total temperature distributions, and phase resolved surface pressure and heat flux on the blade.

The influence on response of axial rotation of a six-group local-conductance probe in horizontal oil-water two-phase flow

NASA Astrophysics Data System (ADS)

Weihang, Kong; Lingfu, Kong; Lei, Li; Xingbin, Liu; Tao, Cui

2017-06-01

Water volume fraction is an important parameter of two-phase flow measurement, and it is an urgent task for accurate measurement in horizontal oil field development and optimization of oil production. The previous ring-shaped conductance water-cut meter cannot obtain the response values corresponding to the oil field water conductivity for oil-water two-phase flow in horizontal oil-producing wells characterized by low yield liquid, low velocity and high water cut. Hence, an inserted axisymmetric array structure sensor, i.e. a six-group local-conductance probe (SGLCP), is proposed in this paper. Firstly, the electric field distributions generated by the exciting electrodes of SGLCP are investigated by the finite element method (FEM), and the spatial sensitivity distributions of SGLCP are analyzed from the aspect of different separations between two electrodes and different axial rotation angles respectively. Secondly, the numerical simulation responses of SGLCP in horizontal segregated flow are calculated from the aspect of different water cut and heights of the water layer, respectively. Lastly, an SGLCP-based well logging instrument was developed, and experiments were carried out in a horizontal pipe with an inner diameter of 125 mm on the industrial-scale experimental multiphase flow setup in the Daqing Oilfield, China. In the experiments, the different oil-water two-phase flow, mineralization degree, temperature and pressure were tested. The results obtained from the simulation experiments and simulation well experiments demonstrate that the designed and developed SGLCP-based instrument still has a good response characteristic for measuring water conductivity under the different conditions mentioned above. The validity and reliability of obtaining the response values corresponding to the water conductivity through the designed and developed SGLCP-based instrument are verified by the experimental results. The significance of this work can provide an effective technology for measuring the water volume fraction of oil-water two-phase flow in horizontal oil-producing wells.

Parametric test results of a swirl-can combustor

NASA Technical Reports Server (NTRS)

Niedzwiecki, R. W.; Jones, R. E.

1973-01-01

Pollutant levels of oxides of nitrogen, unburned hydrocarbons, and carbon monoxide were measured for three models of an experimental, annular swirl can combustor. The combustor was 1.067 meters in outer diameter, incorporated 120 modules, and was specifically designed for elevated exit temperature performance. Test conditions included combustor inlet temperatures of 589, 756 and 839 K, inlet pressures of 3 to 6.4 atmospheres, reference velocities of 21 to 38 meters per second and combustor equivalence ratios, based on total combustor flows of 0.206 to 1.028. Maximum oxides of nitrogen emission index values occurred at an equivalence ratio of 0.7 with lower values measured for both higher and lower equivalence ratios. Oxides of nitrogen concentrations, to the 0.7 level with 756 K inlet air, were correlated for the three models by a combined parameter consisting of measured flow and geometric parameters. Effects of the individual parameters comprising the correlation are also presented.

Calibration and Measurement in Turbulence Research by the Hot-Wire Method

NASA Technical Reports Server (NTRS)

Kovasznay, Kaszlo

1947-01-01

The problem of turbulence in aerodynamics is at present being attacked both theoretically and experimentally. In view of the fact however that purely theoretical considerations have not thus far led to satisfactory results the experimental treatment of the problem is of great importance. Among the different measuring procedures the hot wire methods are so far recognized as the most suitable for investigating the turbulence structure. The several disadvantages of these methods however, in particular those arising from the temperature lag of the wire can greatly impair the measurements and may easily render questionable the entire value of the experiment. The name turbulence is applied to that flow condition in which at any point of the stream the magnitude and direction of the velocity fluctuate arbitrarily about a well definable mean value. This fluctuation imparts a certain whirling characteristic to the flow.

(BOREAS) BOREAS TE-7 Sap Flow Data

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Hogg, E. H.; Hurdle, P. A.

2000-01-01

The BOREAS TE-7 team collected data sets in support of its efforts to characterize and interpret information on the sap flow of boreal vegetation. The heat pulse method was used to monitor sap flow and to estimate rates of transpiration from aspen, black spruce, and mixed wood forests at the SSAOA, MIX, SSA-OBS. and Batoche sites in Saskatchewan, Canada. Measurements were made at the various sites from May to October 1994, May to October 1995, and April to October 1996. A scaling procedure was used to estimate canopy transpiration rates from the sap flow measurements. The data were stored in tabular ASCII files. Analyses to date show a tendency for sap flow in aspen to remain remarkably constant over a wide range of environmental conditions VPD from 1.0 to 4.8 kPa and solar radiation less than 400 W/sq m). For forests with high aerodynamic conductance, the results would indicate an inverse relationship between stomatal conductance and VPD, for VPD greater than 1 kPa. A possible interpretation is that stomata are operating to maintain leaf water potentials above a critical minimum value, which in turn places a maximum value on the rate of sap flow that can be sustained by the tree. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distrobuted Activity Archive Center (DAAC).

High-ionic-strength electroosmotic flows in uncharged hydrophobic nanochannels.

PubMed

Kim, Daejoong; Darve, Eric

2009-02-01

We report molecular dynamics simulation results of high-ionic-strength electroosmotic flows inside uncharged nanochannels. The possibility of this unusual electrokinetic phenomenon has been discussed by Dukhin et al. [A. Dukhin, S. Dukhin, P. Goetz, Langmuir 21 (2005) 9990]. Our computed velocity profiles clearly indicate the presence of a net flow with a maximum velocity around 2 m/s. We found the apparent zeta potential to be -29.7+/-6.8 mV, using the Helmholtz-Smoluchowski relation and the measured mean velocity. This value is comparable to experimentally measured values in Dukhin et al. and references therein. We also investigate the orientations of water molecules in response to an electric field by computing polarization density. Water molecules in the bulk region are oriented along the direction of the external electric field, while their near-wall orientation shows oscillations. The computation of three-dimensional density distributions of sodium and chloride ions around each individual water molecule show that chloride ions tend to concentrate near a water molecule, whereas sodium ions are diffusely distributed.

Calibrant-Free Analyte Quantitation via a Variable Velocity Flow Cell.

PubMed

Beck, Jason G; Skuratovsky, Aleksander; Granger, Michael C; Porter, Marc D

2017-01-17

In this paper, we describe a novel method for analyte quantitation that does not rely on calibrants, internal standards, or calibration curves but, rather, leverages the relationship between disparate and predictable surface-directed analyte flux to an array of sensing addresses and a measured resultant signal. To reduce this concept to practice, we fabricated two flow cells such that the mean linear fluid velocity, U, was varied systematically over an array of electrodes positioned along the flow axis. This resulted in a predictable variation of the address-directed flux of a redox analyte, ferrocenedimethanol (FDM). The resultant limiting currents measured at a series of these electrodes, and accurately described by a convective-diffusive transport model, provided a means to calculate an "unknown" concentration without the use of calibrants, internal standards, or a calibration curve. Furthermore, the experiment and concentration calculation only takes minutes to perform. Deviation in calculated FDM concentrations from true values was minimized to less than 0.5% when empirically derived values of U were employed.

Fuel use control in the fishing industry. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Billington, G.

1985-08-01

The project undertook fuel flow monitoring of a random sample of fishing vessels in the New Zealand fishing industry. The object of the project was to determine the value of fuel flow measurement on a range of vessels of differing size and fishing method, and to investigate the effect on fuel consumption of hull fouling and propeller repitching where this appeared to be required. Eight vessels in the port of Tauranga were included in the trials. Three of these are company-owned and operated and the remainder are owner-operated. One purse seiner, two longliners and five trawlers (pair and single) weremore » involved. Fuel flow measurements were carried out, with before-and-after tests on one vessel to determine the value of removing hull fouling. In two cases propeller repitching was undertaken. The tests demonstrated that five of the eight vessels could, through minor operational changes, make significant fuel conservation gains with minimal loss of performance.« less

Novel Downhole Electromagnetic Flowmeter for Oil-Water Two-Phase Flow in High-Water-Cut Oil-Producing Wells.

PubMed

Wang, Yanjun; Li, Haoyu; Liu, Xingbin; Zhang, Yuhui; Xie, Ronghua; Huang, Chunhui; Hu, Jinhai; Deng, Gang

2016-10-14

First, the measuring principle, the weight function, and the magnetic field of the novel downhole inserted electromagnetic flowmeter (EMF) are described. Second, the basic design of the EMF is described. Third, the dynamic experiments of two EMFs in oil-water two-phase flow are carried out. The experimental errors are analyzed in detail. The experimental results show that the maximum absolute value of the full-scale errors is better than 5%, the total flowrate is 5-60 m³/d, and the water-cut is higher than 60%. The maximum absolute value of the full-scale errors is better than 7%, the total flowrate is 2-60 m³/d, and the water-cut is higher than 70%. Finally, onsite experiments in high-water-cut oil-producing wells are conducted, and the possible reasons for the errors in the onsite experiments are analyzed. It is found that the EMF can provide an effective technology for measuring downhole oil-water two-phase flow.

Novel Downhole Electromagnetic Flowmeter for Oil-Water Two-Phase Flow in High-Water-Cut Oil-Producing Wells

PubMed Central

Wang, Yanjun; Li, Haoyu; Liu, Xingbin; Zhang, Yuhui; Xie, Ronghua; Huang, Chunhui; Hu, Jinhai; Deng, Gang

2016-01-01

First, the measuring principle, the weight function, and the magnetic field of the novel downhole inserted electromagnetic flowmeter (EMF) are described. Second, the basic design of the EMF is described. Third, the dynamic experiments of two EMFs in oil-water two-phase flow are carried out. The experimental errors are analyzed in detail. The experimental results show that the maximum absolute value of the full-scale errors is better than 5%, the total flowrate is 5–60 m3/d, and the water-cut is higher than 60%. The maximum absolute value of the full-scale errors is better than 7%, the total flowrate is 2–60 m3/d, and the water-cut is higher than 70%. Finally, onsite experiments in high-water-cut oil-producing wells are conducted, and the possible reasons for the errors in the onsite experiments are analyzed. It is found that the EMF can provide an effective technology for measuring downhole oil-water two-phase flow. PMID:27754412

Analytical and experimental study of mean flow and turbulence characteristics inside the passages of an axial flow inducer

NASA Technical Reports Server (NTRS)

Gorton, C. A.; Lakshminarayana, B.

1974-01-01

The effort conducted to gather additional understanding of the complex inviscid and viscid effects existing within the passages of a three-bladed axial flow inducer operating at a flow coefficient of 0.065 is summarized. The experimental investigations included determination of the blade static pressure and blade limiting streamline angle distributions, and measurement of the three components of mean velocity, turbulence intensities and turbulence stresses at locations inside the inducer blade passage utilizing a rotating three-sensor hotwire probe. Applicable equations were derived for the hotwire data reduction analysis and solved numerically to obtain the appropriate flow parameters. Analytical investigations were conducted to predict the three-dimensional inviscid flow in the inducer by numerically solving the exact equations of motion, and to approximately predict the three-dimensional viscid flow by incorporating the dominant viscous terms into the exact equations. The analytical results are compared with the experimental measurements and design values where appropriate.

A study of methods to estimate debris flow velocity

USGS Publications Warehouse

Prochaska, A.B.; Santi, P.M.; Higgins, J.D.; Cannon, S.H.

2008-01-01

Debris flow velocities are commonly back-calculated from superelevation events which require subjective estimates of radii of curvature of bends in the debris flow channel or predicted using flow equations that require the selection of appropriate rheological models and material property inputs. This research investigated difficulties associated with the use of these conventional velocity estimation methods. Radii of curvature estimates were found to vary with the extent of the channel investigated and with the scale of the media used, and back-calculated velocities varied among different investigated locations along a channel. Distinct populations of Bingham properties were found to exist between those measured by laboratory tests and those back-calculated from field data; thus, laboratory-obtained values would not be representative of field-scale debris flow behavior. To avoid these difficulties with conventional methods, a new preliminary velocity estimation method is presented that statistically relates flow velocity to the channel slope and the flow depth. This method presents ranges of reasonable velocity predictions based on 30 previously measured velocities. ?? 2008 Springer-Verlag.

Mean velocities and Reynolds stresses upstream of a simulated wing-fuselage juncture

NASA Technical Reports Server (NTRS)

Mcmahon, H.; Hubbartt, J.; Kubendran, L. R.

1983-01-01

Values of three mean velocity components and six turbulence stresses measured in a turbulent shear layer upstream of a simulated wing-fuselage juncture and immediately downstream of the start of the juncture are presented nd discussed. Two single-sensor hot-wire probes were used in the measurements. The separated region just upstream of the wing contains an area of reversed flow near the fuselage surface where the turbulence level is high. Outside of this area the flow skews as it passes around the body, and in this skewed region the magnitude and distribution of the turbulent normal and shear stresses within the shear layer are modified slightly by the skewing and deceleration of the flow. A short distance downstream of the wing leading edge the secondary flow vortext is tightly rolled up and redistributes both mean flow and turbulence in the juncture. The data acquisition technique employed here allows a hot wire to be used in a reversed flow region to indicate flow direction.

Heat flow in the SAFOD pilot hole and implications for the strength of the San Andreas Fault

USGS Publications Warehouse

Williams, C.F.; Grubb, F.V.; Galanis, S.P.

2004-01-01

Detailed thermal measurements have been acquired in the 2.2-km-deep SAFOD pilot hole, located 1.8 km west of the SAF near Parkfield, California. Heat flow from the basement section of the borehole (770 to 2160 m) is 91 mW m-2, higher than the published 74 mW m -2 average for the Parkfield area. Within the resolution of the measurements, heat flow is constant across faults that intersect the borehole, suggesting that fluid flow does not alter the conductive thermal regime. Reanalysis of regional heat flow reveals an increase in heat flow along the SAF northwest of Parkfield. This transition corresponds to a shallowing base of seismicity and a change in fault behavior near the northern terminus of the M6 1966 Parkfield earthquake rupture. The persistence of elevated heat flow in the Coast Ranges to the west appears to rule out frictional heating on the SAF as the source of the SAFOD value.

New heat flow measurements in Oman and the thermal state of the Arabian Shield and Platform

NASA Astrophysics Data System (ADS)

Rolandone, Frédérique; Lucazeau, Francis; Leroy, Sylvie; Mareschal, Jean-Claude; Jorand, Rachel; Goutorbe, Bruno; Bouquerel, Hélène

2013-03-01

The present-day thermal regime of the Arabian plate is affected by the dynamics of the Afar plume and the rifting of the Red Sea and the Gulf of Aden. The Arabian plate is a Precambrian Shield and its thermal regime, before the plume and rifting activities, should be similar to that of other Precambrian Shields with a thick lithosphere. This is consistent with low heat-flow values measured in Saudi Arabia (35-44 mWm- 2), but not with recent measurements in Jordan that show higher heat flow (56-66 mWm- 2). We have conducted measurements in the eastern Arabian plate to obtain 10 new heat-flux values. We also derived 20 heat-flux values from oil exploration wells. Our measurements show that surface heat flux is uniformly low (45 mWm- 2) in the eastern Arabian Shield and is consistent with low crustal heat production (0.7 μWm- 3). A steady-state geotherm for the Arabian platform that intersects the isentropic temperature profile at a depth of 150 km is consistent with the seismic observations. Differences in heat flow between the eastern (60 mWm- 2) and the western (45 mWm- 2) parts of Arabia reflect differences in crustal heat production as well as a higher mantle heat flux in the west. Seismic tomography studies of the mantle beneath Arabia show this east-west contrast. The lithospheric thickness for the Arabian plate is 150 km, and the progressive thinning near the Red Sea is caused by the thermal erosion of the plume. The Afar plume mostly affects the base of the Arabian lithosphere along the Red Sea and the western part of the Gulf of Aden by channeling magmas from the asthenosphere through the rift. The continental domain is not affected by rifting in the Gulf of Aden. The main thermal effect of the Arabian plate is probably the channeling of the Afar plume to the North.

Measurements of slip length for flows over graphite surface with gas domains

NASA Astrophysics Data System (ADS)

Li, Dayong; Wang, Yuliang; Pan, Yunlu; Zhao, Xuezeng

2016-10-01

We present the measurements of slip lengths for the flows of purified water over graphite surface covered with surface nanobubbles or nano/micropancakes, which can be produced after using high temperature water to replace low temperature water. The slip length values measured on bare graphite surface, nano/micropancake or nanobubble covered graphite surfaces are about 8 nm, 27 nm, and 63 nm, respectively. Our results indicate that the gaseous domains formed at the solid-liquid interface, including surface nanobubbles and nano/micropancakes, could act as a lubricant and significantly increase slip length.

A comparison of mean parotid gland dose with measures of parotid gland function after radiotherapy for head-and-neck cancer: Implications for future trials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roesink, Judith M.; Schipper, Maria; Busschers, Wim

2005-11-15

Purpose: To determine the most adequate parameter to measure the consequences of reducing the parotid gland dose. Methods and Materials: One hundred eight patients treated with radiotherapy for various malignancies of the head and neck were prospectively evaluated using three methods. Parotid gland function was objectively determined by measuring stimulated parotid flow using Lashley cups and scintigraphy. To assess xerostomia-related quality of life, the head-and-neck cancer module European Organization for Research and Treatment of Cancer QLQ (Quality of Life Questionnaire) H and N35 was used. Measurements took place before radiotherapy and 6 weeks and 12 months after the completion ofmore » radiotherapy. Complication was defined for each method using cutoff values. The correlation between these complications and the mean parotid gland dose was investigated to find the best measure for parotid gland function. Results: For both flow and scintigraphy data, the best definition for objective parotid gland toxicity seemed to be reduction of stimulated parotid flow to {<=}25% of the preradiotherapy flow. Of all the subjective variables, only the single item dry mouth 6 weeks after radiotherapy was found to be significant. The best correlation with the mean parotid gland dose was found for the stimulated flow measurements. The predictive ability was the highest for the time point 1 year after radiotherapy. Subjective findings did not correlate with the mean parotid dose. Conclusions: Stimulated flow measurements using Lashley cups, with a complication defined as flow {<=}25% of the preradiotherapy output, correlated best with the mean parotid gland dose. When reduction of the mean dose to the parotid gland is intended, the stimulated flow measurement is the best method for evaluating parotid gland function.« less

Longitudinal optical monitoring of blood flow in breast tumors during neoadjuvant chemotherapy

NASA Astrophysics Data System (ADS)

Cochran, J. M.; Chung, S. H.; Leproux, A.; Baker, W. B.; Busch, D. R.; DeMichele, A. M.; Tchou, J.; Tromberg, B. J.; Yodh, A. G.

2017-06-01

We measure tissue blood flow markers in breast tumors during neoadjuvant chemotherapy and investigate their correlation to pathologic complete response in a pilot longitudinal patient study (n  =  4). Tumor blood flow is quantified optically by diffuse correlation spectroscopy (DCS), and tissue optical properties, blood oxygen saturation, and total hemoglobin concentration are derived from concurrent diffuse optical spectroscopic imaging (DOSI). The study represents the first longitudinal DCS measurement of neoadjuvant chemotherapy in humans over the entire course of treatment; it therefore offers a first correlation between DCS flow indices and pathologic complete response. The use of absolute optical properties measured by DOSI facilitates significant improvement of DCS blood flow calculation, which typically assumes optical properties based on literature values. Additionally, the combination of the DCS blood flow index and the tissue oxygen saturation from DOSI permits investigation of tissue oxygen metabolism. Pilot results from four patients suggest that lower blood flow in the lesion-bearing breast is correlated with pathologic complete response. Both absolute lesion blood flow and lesion flow relative to the contralateral breast exhibit potential for characterization of pathological response. This initial demonstration of the combined optical approach for chemotherapy monitoring provides incentive for more comprehensive studies in the future and can help power those investigations.

Parametric Characterization of Flow Inside Cererbal Aneurysms Treated with Flow-Diverting Stents

NASA Astrophysics Data System (ADS)

Barbour, Michael; Levitt, Michael; Geindreau, Christian; Johnson, Luke; Chivukula, Keshav; Aliseda, Alberto

2017-11-01

Cerebral aneurysms are often treated with a flow-diverting stent (FDS) to reduce blood flow into the aneurysm sac, promoting the development of a stable thrombus. Successful treatment is highly dependent on the degree of flow reduction and the altered hemodynamics inside the aneurysm sac following treatment. Establishing a causal connection between hemodynamic metrics of FDS-treated CAs and long-term clinical outcomes requires a rigorous parametric characterization of this flow environment. We use 3D particle image velocimetry (PIV) to measure the flow inside idealized aneurysm models treated with FDS. Physiologically realistic Reynolds numbers and increasing levels of parent vessel curvature are analyzed to understand the effect of inertia on flow development. The flow velocity into the aneurysm and the topology of the flow inside the sac is shown to be highly dependent on parent vessel Dean number (De). The role of flow pulsatility is then added to the study via time-dependent waveforms. Velocity measurements at 2 values of parent vessel Womersley number (Wo) allow us to parameterize flow inside of CAs treated with FDS as a function of De, Re and Wo, improving the fundamental understanding of how FDS alter CA hemodynamics and aiding in the development of new treatments.

Optimization design of submerged propeller in oxidation ditch by computational fluid dynamics and comparison with experiments.

PubMed

Zhang, Yuquan; Zheng, Yuan; Fernandez-Rodriguez, E; Yang, Chunxia; Zhu, Yantao; Liu, Huiwen; Jiang, Hao

The operating condition of a submerged propeller has a significant impact on flow field and energy consumption of the oxidation ditch. An experimentally validated numerical model, based on the computational fluid dynamics (CFD) tool, is presented to optimize the operating condition by considering two important factors: flow field and energy consumption. Performance demonstration and comparison of different operating conditions were carried out in a Carrousel oxidation ditch at the Yingtang wastewater treatment plants in Anhui Province, China. By adjusting the position and rotating speed together with the number of submerged propellers, problems of sludge deposit and the low velocity in the bend could be solved in a most cost-effective way. The simulated results were acceptable compared with the experimental data and the following results were obtained. The CFD model characterized flow pattern and energy consumption in the full-scale oxidation ditch. The predicted flow field values were within -1.28 ± 7.14% difference from the measured values. By determining three sets of propellers under the rotating speed of 6.50 rad/s with one located 5 m from the first curved wall, after numerical simulation and actual measurement, not only the least power density but also the requirement of the flow pattern could be realized.

Probable flood predictions in ungauged coastal basins of El Salvador

USGS Publications Warehouse

Friedel, M.J.; Smith, M.E.; Chica, A.M.E.; Litke, D.

2008-01-01

A regionalization procedure is presented and used to predict probable flooding in four ungauged coastal river basins of El Salvador: Paz, Jiboa, Grande de San Miguel, and Goascoran. The flood-prediction problem is sequentially solved for two regions: upstream mountains and downstream alluvial plains. In the upstream mountains, a set of rainfall-runoff parameter values and recurrent peak-flow discharge hydrographs are simultaneously estimated for 20 tributary-basin models. Application of dissimilarity equations among tributary basins (soft prior information) permitted development of a parsimonious parameter structure subject to information content in the recurrent peak-flow discharge values derived using regression equations based on measurements recorded outside the ungauged study basins. The estimated joint set of parameter values formed the basis from which probable minimum and maximum peak-flow discharge limits were then estimated revealing that prediction uncertainty increases with basin size. In the downstream alluvial plain, model application of the estimated minimum and maximum peak-flow hydrographs facilitated simulation of probable 100-year flood-flow depths in confined canyons and across unconfined coastal alluvial plains. The regionalization procedure provides a tool for hydrologic risk assessment and flood protection planning that is not restricted to the case presented herein. ?? 2008 ASCE.

The experimental verification of a streamline curvature numerical analysis method applied to the flow through an axial flow fan

NASA Technical Reports Server (NTRS)

Pierzga, M. J.

1981-01-01

The experimental verification of an inviscid, incompressible through-flow analysis method is presented. The primary component of this method is an axisymmetric streamline curvature technique which is used to compute the hub-to-tip flow field of a given turbomachine. To analyze the flow field in the blade-to-blade plane of the machine, the potential flow solution of an infinite cascade of airfoils is also computed using a source model technique. To verify the accuracy of such an analysis method an extensive experimental verification investigation was conducted using an axial flow research fan. Detailed surveys of the blade-free regions of the machine along with intra-blade surveys using rotating pressure sensing probes and blade surface static pressure taps provide a one-to-one relationship between measured and predicted data. The results of this investigation indicate the ability of this inviscid analysis method to predict the design flow field of the axial flow fan test rotor to within a few percent of the measured values.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burton, H.W.; Stevenson, T.R.; Dysko, R.C.

The transplantation of whole skeletal muscles is a common clinical procedure. Although atypical blood flows have been reported in small free muscle grafts, the blood flow of large neurovascular-intact (NVI) and neurovascular-anastomosed (NVA) grafts have not been measured. Because the maximum specific force (N/cm{sup 2}) of NVI and NVA grafts is 65% that of control muscles, we hypothesized that total and regional blood flows of NVI and NVA grafts at rest and during twitch contractions are significantly lower than lower flows of control muscles. In rabbits, blood flows of control rectus femoris (RFM) muscles and NVI and NVA grafts ofmore » RFM muscles were measured by the radioactive-microsphere technique. Total blood flows in grafts were not different from the control RFM muscle values, except for a higher resting flow in NVA grafts and a lower flow at 3 Hz in NVI grafts. Minor variations in regional flows were observed. We conclude that the operative procedures of grating and repair of blood vessels affect the vascular bed of muscles minimally, and the deficits observed in grafts do not arise from inadequate perfusion.« less

Blunted postprandial reaction of portal venous flow in chronic liver disease, assessed with duplex Doppler: significance for prognosis.

PubMed

de Vries, P J; de Hooge, P; Hoekstra, J B; van Hattum, J

1994-12-01

To establish the effects of a meal on portal venous flow and the prognostic value of this parameter, 46 patients with chronic liver disease and 28 healthy subjects were examined with duplex Doppler before and after a meal. The measurements were completed in 40 patients and 21 healthy subjects. Postprandial portal venous diameter, blood velocity and quantitative flow were measured for 60 min. Mean baseline values were: 11.4 mm versus 10.2 mm (p = 0.019), 10.8 cm.s-1 versus 13.4 cm.s-1 (p = 0.015) and 668 ml.min-1 versus 646 ml.min-1 (p = 0.7) respectively. Spleen size was 15.0 cm versus 10.6 cm (p = 0.0001) respectively. Postprandial diameter, velocity and flow increased significantly in patients and controls (p = 0.0001 for all). Mean postprandial flow could best be described by a polynomial equation with a parabolic curve. Patients' curves were more blunted than controls', with significantly different regression constants (p = 0.025 and p = 0.029). All subjects were followed up for survival and variceal haemorrhage. The mean follow-up time was 47 months. Early maximum postprandial velocity (p = 0.041) and large spleen size (p = 0.002) were significantly related to an unfavourable prognosis for survival. Early maximum velocity was also related to increased variceal haemorrhage. This study shows that postprandial portal venous flow is blunted in patients with chronic liver disease. Postprandial portal venous flow may have prognostic significance.

Application of nonlinear least-squares regression to ground-water flow modeling, west-central Florida

USGS Publications Warehouse

Yobbi, D.K.

2000-01-01

A nonlinear least-squares regression technique for estimation of ground-water flow model parameters was applied to an existing model of the regional aquifer system underlying west-central Florida. The regression technique minimizes the differences between measured and simulated water levels. Regression statistics, including parameter sensitivities and correlations, were calculated for reported parameter values in the existing model. Optimal parameter values for selected hydrologic variables of interest are estimated by nonlinear regression. Optimal estimates of parameter values are about 140 times greater than and about 0.01 times less than reported values. Independently estimating all parameters by nonlinear regression was impossible, given the existing zonation structure and number of observations, because of parameter insensitivity and correlation. Although the model yields parameter values similar to those estimated by other methods and reproduces the measured water levels reasonably accurately, a simpler parameter structure should be considered. Some possible ways of improving model calibration are to: (1) modify the defined parameter-zonation structure by omitting and/or combining parameters to be estimated; (2) carefully eliminate observation data based on evidence that they are likely to be biased; (3) collect additional water-level data; (4) assign values to insensitive parameters, and (5) estimate the most sensitive parameters first, then, using the optimized values for these parameters, estimate the entire data set.

Comparison of thermal, salt and dye tracing to estimate shallow flow velocities: Novel triple-tracer approach

NASA Astrophysics Data System (ADS)

Abrantes, João R. C. B.; Moruzzi, Rodrigo B.; Silveira, Alexandre; de Lima, João L. M. P.

2018-02-01

The accurate measurement of shallow flow velocities is crucial to understand and model the dynamics of sediment and pollutant transport by overland flow. In this study, a novel triple-tracer approach was used to re-evaluate and compare the traditional and well established dye and salt tracer techniques with the more recent thermal tracer technique in estimating shallow flow velocities. For this purpose a triple tracer (i.e. dyed-salted-heated water) was used. Optical and infrared video cameras and an electrical conductivity sensor were used to detect the tracers in the flow. Leading edge and centroid velocities of the tracers were measured and the correction factors used to determine the actual mean flow velocities from tracer measured velocities were compared and investigated. Experiments were carried out for different flow discharges (32-1813 ml s-1) on smooth acrylic, sand, stones and synthetic grass bed surfaces with 0.8, 4.4 and 13.2% slopes. The results showed that thermal tracers can be used to estimate shallow flow velocities, since the three techniques yielded very similar results without significant differences between them. The main advantages of the thermal tracer were that the movement of the tracer along the measuring section was more easily visible than it was in the real image videos and that it was possible to measure space-averaged flow velocities instead of only one velocity value, with the salt tracer. The correction factors used to determine the actual mean velocity of overland flow varied directly with Reynolds and Froude numbers, flow velocity and slope and inversely with flow depth and bed roughness. In shallow flows, velocity estimation using tracers entails considerable uncertainty and caution must be taken with these measurements, especially in field studies where these variables vary appreciably in space and time.

Experimental evaluation of heat transfer on a 1030:1 area ratio rocket nozzle

NASA Technical Reports Server (NTRS)

Kacynski, Kenneth J.; Pavli, Albert J.; Smith, Tamara A.

1987-01-01

A 1030:1 carbon steel, heat-sink nozzle was tested. The test conditions included a nominal chamber pressure of 2413 kN/sq m and a mixture ratio range of 2.78 to 5.49. The propellants were gaseous oxygen and gaseous hydrogen. Outer wall temperature measurements were used to calculate the inner wall temperature and the heat flux and heat rate to the nozzle at specified axial locations. The experimental heat fluxes were compared to those predicted by the Two-Dimensional Kinetics (TDK) computer model analysis program. When laminar boundary layer flow was assumed in the analysis, the predicted values were within 15 percent of the experimental values for the area ratios of 20 to 975. However, when turbulent boundary layer conditions were assumed, the predicted values were approximately 120 percent higher than the experimental values. A study was performed to determine if the conditions within the nozzle could sustain a laminar boundary layer. Using the flow properties predicted by TDK, the momentum-thickness Reynolds number was calculated, and the point of transition to turbulent flow was predicted. The predicted transition point was within 0.5 inches of the nozzle throat. Calculations of the acceleration parameter were then made to determine if the flow conditions could produce relaminarization of the boundary layer. It was determined that if the boundary layer flow was inclined to transition to turbulent, the acceleration conditions within the nozzle would tend to suppress turbulence and keep the flow laminar-like.

Experimental evaluation of heat transfer on a 1030:1 area ratio rocket nozzle

NASA Technical Reports Server (NTRS)

Kacynski, Kenneth J.; Pavli, Albert J.; Smith, Tamara A.

1987-01-01

A 1030:1 carbon steel, heat-sink nozzle was tested. The test conditions included a nominal chamber pressure of 2413 kN/sq m and a mixture ratio range of 2.78 to 5.49. The propellants were gaseous oxygen and gaseous hydrogen. Outer wall temperature measurements were used to calculate the inner wall temperature and the heat flux and heat rate to the nozzle at specified axial locations. The experimental heat fluxes were compared to those predicted by the Two-Dimensional Kinetics (TDK) computer model analysis program. When laminar boundary layer flow was assumed in the analysis, the predicted values were within 15% of the experimental values for the area ratios of 20 to 975. However, when turbulent boundary layer conditions were assumed, the predicted values were approximately 120% higher than the experimental values. A study was performed to determine if the conditions within the nozzle could sustain a laminar boundary layer. Using the flow properties predicted by TDK, the momentum-thickness Reynolds number was calculated, and the point of transition to turbulent flow was predicted. The predicted transition point was within 0.5 inches of the nozzle throat. Calculations of the acceleration parameter were then made to determine if the flow conditions could produce relaminarization of the boundary layer. It was determined that if the boundary layer flow was inclined to transition to turbulent, the acceleration conditions within the nozzle would tend to suppress turbulence and keep the flow laminar-like.

40 CFR 1065.307 - Linearity verification.

Code of Federal Regulations, 2012 CFR

2012-07-01

... meter at different flow rates. Use a gravimetric reference measurement (such as a scale, balance, or... nitrogen. Select gas divisions that you typically use. Use a selected gas division as the measured value.... For linearity verification for gravimetric PM balances, use external calibration weights that that...

40 CFR 1065.307 - Linearity verification.

Code of Federal Regulations, 2013 CFR

2013-07-01

... meter at different flow rates. Use a gravimetric reference measurement (such as a scale, balance, or... nitrogen. Select gas divisions that you typically use. Use a selected gas division as the measured value.... For linearity verification for gravimetric PM balances, use external calibration weights that that...

Prediction of hydrographs and flow-duration curves in almost ungauged catchments: Which runoff measurements are most informative for model calibration?

NASA Astrophysics Data System (ADS)

Pool, Sandra; Viviroli, Daniel; Seibert, Jan

2017-11-01

Applications of runoff models usually rely on long and continuous runoff time series for model calibration. However, many catchments around the world are ungauged and estimating runoff for these catchments is challenging. One approach is to perform a few runoff measurements in a previously fully ungauged catchment and to constrain a runoff model by these measurements. In this study we investigated the value of such individual runoff measurements when taken at strategic points in time for applying a bucket-type runoff model (HBV) in ungauged catchments. Based on the assumption that a limited number of runoff measurements can be taken, we sought the optimal sampling strategy (i.e. when to measure the streamflow) to obtain the most informative data for constraining the runoff model. We used twenty gauged catchments across the eastern US, made the assumption that these catchments were ungauged, and applied different runoff sampling strategies. All tested strategies consisted of twelve runoff measurements within one year and ranged from simply using monthly flow maxima to a more complex selection of observation times. In each case the twelve runoff measurements were used to select 100 best parameter sets using a Monte Carlo calibration approach. Runoff simulations using these 'informed' parameter sets were then evaluated for an independent validation period in terms of the Nash-Sutcliffe efficiency of the hydrograph and the mean absolute relative error of the flow-duration curve. Model performance measures were normalized by relating them to an upper and a lower benchmark representing a well-informed and an uninformed model calibration. The hydrographs were best simulated with strategies including high runoff magnitudes as opposed to the flow-duration curves that were generally better estimated with strategies that captured low and mean flows. The choice of a sampling strategy covering the full range of runoff magnitudes enabled hydrograph and flow-duration curve simulations close to a well-informed model calibration. The differences among such strategies covering the full range of runoff magnitudes were small indicating that the exact choice of a strategy might be less crucial. Our study corroborates the information value of a small number of strategically selected runoff measurements for simulating runoff with a bucket-type runoff model in almost ungauged catchments.

Regional cerebral blood flow in childhood headache

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roach, E.S.; Stump, D.A.

1989-06-01

Regional cerebral blood flow (rCBF) was measured in 16 cranial regions in 23 children and adolescents with frequent headaches using the non-invasive Xenon-133 inhalation technique. Blood flow response to 5% carbon dioxide (CO2) was also determined in 21 patients, while response to 50% oxygen was measured in the two patients with hemoglobinopathy. Included were 10 patients with a clinical diagnosis of migraine, 4 with musculoskeletal headaches, and 3 with features of both types. Also studied were 2 patients with primary thrombocythemia, 2 patients with hemoglobinopathy and headaches, 1 patient with polycythemia, and 1 with headaches following trauma. With two exceptions,more » rCBF determinations were done during an asymptomatic period. Baseline rCBF values tended to be higher in these young patients than in young adults done in our laboratory. Localized reduction in the expected blood flow surge after CO2 inhalation, most often noted posteriorly, was seen in 8 of the 13 vascular headaches, but in none of the musculoskeletal headache group. Both patients with primary thrombocythemia had normal baseline flow values and altered responsiveness to CO2 similar to that seen in migraineurs; thus, the frequently reported headache and transient neurologic signs with primary thrombocythemia are probably not due to microvascular obstruction as previously suggested. These data support the concept of pediatric migraine as a disorder of vasomotor function and also add to our knowledge of normal rCBF values in younger patients. Demonstration of altered vasomotor reactivity to CO2 could prove helpful in children whose headache is atypical.« less

Modification of Turbulent Pipe Flow Equations to Estimate the Vertical Velocity Profiles Under Woody Debris Jams

NASA Astrophysics Data System (ADS)

Cervania, A.; Knack, I. M. W.

2017-12-01

The presence of woody debris (WD) jams in rivers and streams increases the risk of backwater flooding and reduces the navigability of a channel, but adds fish and macroinvertebrate habitat to the stream. When designing river engineering projects engineers use hydraulic models to predict flow behavior around these obstructions. However, the complexities of flow through and beneath WD jams are still poorly understood. By increasing the ability to predict flow behavior around WD jams, landowners and engineers are empowered to develop sustainable practices regarding the removal or placement of WD in rivers and flood plains to balance the desirable and undesirable effects to society and the environment. The objective of this study is to address some of this knowledge gap by developing a method to estimate the vertical velocity profile of flow under WD jams. When flow passes under WD jams, it becomes affected by roughness elements on all sides, similar to turbulent flows in pipe systems. Therefore, the method was developed using equations that define the velocity profiles of turbulent pipe flows: the law of the wall, the logarithmic law, and the velocity defect law. Flume simulations of WD jams were conducted and the vertical velocity profiles were measured along the centerline. A calculated velocity profile was fit to the measured profile through the calibration of eight parameters. An optimal value or range of values have been determined for several of these parameters using cross-validation techniques. The results indicate there may be some promise to using this method in hydraulic models.

An Experimental Study of Turbulent Skin Friction Reduction in Supersonic Flow Using a Microblowing Technique

NASA Technical Reports Server (NTRS)

Hwang, Danny P.

1999-01-01

A new turbulent skin friction reduction technology, called the microblowing technique has been tested in supersonic flow (Mach number of 1.9) on specially designed porous plates with microholes. The skin friction was measured directly by a force balance and the boundary layer development was measured by a total pressure rake at the tailing edge of a test plate. The free stream Reynolds number was 1.0(10 exp 6) per meter. The turbulent skin friction coefficient ratios (C(sub f)/C(sub f0)) of seven porous plates are given in this report. Test results showed that the microblowing technique could reduce the turbulent skin friction in supersonic flow (up to 90 percent below a solid flat plate value, which was even greater than in subsonic flow).

An electrical analogy relating the Atlantic multidecadal oscillation to the Atlantic meridional overturning circulation.

PubMed

Kurtz, Bruce E

2014-01-01

The Atlantic meridional overturning circulation (AMOC) is the northward flow of surface water to subpolar latitudes where deepwater is formed, balanced by southward abyssal flow and upwelling in the vicinity of the Southern Ocean. It is generally accepted that AMOC flow oscillates with a period of 60-80 years, creating a regular variation in North Atlantic sea surface temperature known as the Atlantic multidecadal oscillation (AMO). This article attempts to answer two questions: how is the AMOC driven and why does it oscillate? Using methods commonly employed by chemical engineers for analyzing processes involving flowing liquids, apparently not previously applied to trying to understand the AMOC, an equation is developed for AMOC flow as a function of the meridional density gradient or the corresponding temperature gradient. The equation is based on the similarity between the AMOC and an industrial thermosyphon loop cooler, which circulates a heat transfer liquid without using a mechanical pump. Extending this equation with an analogy between the flow of heat and electricity explains why the AMOC flow oscillates and what determines its period. Calculated values for AMOC flow and AMO oscillation period are in good agreement with measured values.

An Electrical Analogy Relating the Atlantic Multidecadal Oscillation to the Atlantic Meridional Overturning Circulation

PubMed Central

Kurtz, Bruce E.

2014-01-01

The Atlantic meridional overturning circulation (AMOC) is the northward flow of surface water to subpolar latitudes where deepwater is formed, balanced by southward abyssal flow and upwelling in the vicinity of the Southern Ocean. It is generally accepted that AMOC flow oscillates with a period of 60–80 years, creating a regular variation in North Atlantic sea surface temperature known as the Atlantic multidecadal oscillation (AMO). This article attempts to answer two questions: how is the AMOC driven and why does it oscillate? Using methods commonly employed by chemical engineers for analyzing processes involving flowing liquids, apparently not previously applied to trying to understand the AMOC, an equation is developed for AMOC flow as a function of the meridional density gradient or the corresponding temperature gradient. The equation is based on the similarity between the AMOC and an industrial thermosyphon loop cooler, which circulates a heat transfer liquid without using a mechanical pump. Extending this equation with an analogy between the flow of heat and electricity explains why the AMOC flow oscillates and what determines its period. Calculated values for AMOC flow and AMO oscillation period are in good agreement with measured values. PMID:24940739

The 400 microsphere per piece "rule" does not apply to all blood flow studies.

PubMed

Polissar, N L; Stanford, D C; Glenny, R W

2000-01-01

Microsphere experiments are useful in measuring regional organ perfusion as well as heterogeneity of blood flow within organs and correlation of perfusion between organ pieces at different time points. A 400 microspheres/piece "rule" is often used in planning experiments or to determine whether experiments are valid. This rule is based on the statement that 400 microspheres must lodge in a region for 95% confidence that the observed flow in the region is within 10% of the true flow. The 400 microspheres precision rule, however, only applies to measurements of perfusion to a single region or organ piece. Examples, simulations, and an animal experiment were carried out to show that good precision for measurements of heterogeneity and correlation can be obtained from many experiments with <400 microspheres/piece. Furthermore, methods were developed and tested for correcting the observed heterogeneity and correlation to remove the Poisson "noise" due to discrete microsphere measurements. The animal experiment shows adjusted values of heterogeneity and correlation that are in close agreement for measurements made with many or few microspheres/piece. Simulations demonstrate that the adjusted values are accurate for a variety of experiments with far fewer than 400 microspheres/piece. Thus the 400 microspheres rule does not apply to many experiments. A "rule of thumb" is that experiments with a total of at least 15,000 microspheres, for all pieces combined, are very likely to yield accurate estimates of heterogeneity. Experiments with a total of at least 25,000 microspheres are very likely to yield accurate estimates of correlation coefficients.

Measurement and prediction of model-rotor flow fields

NASA Technical Reports Server (NTRS)

Owen, F. K.; Tauber, M. E.

1985-01-01

This paper shows that a laser velocimeter can be used to measure accurately the three-component velocities induced by a model rotor at transonic tip speeds. The measurements, which were made at Mach numbers from 0.85 to 0.95 and at zero advance ratio, yielded high-resolution, orthogonal velocity values. The measured velocities were used to check the ability of the ROT22 full-potential rotor code to predict accurately the transonic flow field in the crucial region around and beyond the tip of a high-speed rotor blade. The good agreement between the calculated and measured velocities established the code's ability to predict the off-blade flow field at transonic tip speeds. This supplements previous comparisons in which surface pressures were shown to be well predicted on two different tips at advance ratios to 0.45, especially at the critical 90 deg azimuthal blade position. These results demonstrate that the ROT22 code can be used with confidence to predict the important tip-region flow field, including the occurrence, strength, and location of shock waves causing high drag and noise.

Experimental validation of a self-calibrating cryogenic mass flowmeter

NASA Astrophysics Data System (ADS)

Janzen, A.; Boersch, M.; Burger, B.; Drache, J.; Ebersoldt, A.; Erni, P.; Feldbusch, F.; Oertig, D.; Grohmann, S.

2017-12-01

The Karlsruhe Institute of Technology (KIT) and the WEKA AG jointly develop a commercial flowmeter for application in helium cryostats. The flowmeter functions according to a new thermal measurement principle that eliminates all systematic uncertainties and enables self-calibration during real operation. Ideally, the resulting uncertainty of the measured flow rate is only dependent on signal noises, which are typically very small with regard to the measured value. Under real operating conditions, cryoplant-dependent flow rate fluctuations induce an additional uncertainty, which follows from the sensitivity of the method. This paper presents experimental results with helium at temperatures between 30 and 70 K and flow rates in the range of 4 to 12 g/s. The experiments were carried out in a control cryostat of the 2 kW helium refrigerator of the TOSKA test facility at KIT. Inside the cryostat, the new flowmeter was installed in series with a Venturi tube that was used for reference measurements. The measurement results demonstrate the self-calibration capability during real cryoplant operation. The influences of temperature and flow rate fluctuations on the self-calibration uncertainty are discussed.

Software-based on-site estimation of fractional flow reserve using standard coronary CT angiography data.

PubMed

De Geer, Jakob; Sandstedt, Mårten; Björkholm, Anders; Alfredsson, Joakim; Janzon, Magnus; Engvall, Jan; Persson, Anders

2016-10-01

The significance of a coronary stenosis can be determined by measuring the fractional flow reserve (FFR) during invasive coronary angiography. Recently, methods have been developed which claim to be able to estimate FFR using image data from standard coronary computed tomography angiography (CCTA) exams. To evaluate the accuracy of non-invasively computed fractional flow reserve (cFFR) from CCTA. A total of 23 vessels in 21 patients who had undergone both CCTA and invasive angiography with FFR measurement were evaluated using a cFFR software prototype. The cFFR results were compared to the invasively obtained FFR values. Correlation was calculated using Spearman's rank correlation, and agreement using intraclass correlation coefficient (ICC). Sensitivity, specificity, accuracy, negative predictive value, and positive predictive value for significant stenosis (defined as both FFR ≤0.80 and FFR ≤0.75) were calculated. The mean cFFR value for the whole group was 0.81 and the corresponding mean invFFR value was 0.84. The cFFR sensitivity for significant stenosis (FFR ≤0.80/0.75) on a per-lesion basis was 0.83/0.80, specificity was 0.76/0.89, and accuracy 0.78/0.87. The positive predictive value was 0.56/0.67 and the negative predictive value was 0.93/0.94. The Spearman rank correlation coefficient was ρ = 0.77 (P < 0.001) and ICC = 0.73 (P < 0.001). This particular CCTA-based cFFR software prototype allows for a rapid, non-invasive on-site evaluation of cFFR. The results are encouraging and cFFR may in the future be of help in the triage to invasive coronary angiography. © The Foundation Acta Radiologica 2015.

[Quantification and monitoring of vascular resistance in the lower limbs by the Doppler method (animal model)

NASA Technical Reports Server (NTRS)

Arbeille, P.; Berson, M.; Blondeau, B.; Durand, A.; Bodard, S.; Locatelli, A.; Fox, G. E. (Principal Investigator)

1995-01-01

The object of this study was to define and validate a non-invasive method of evaluation and monitoring of vascular resistances in the leg. Blood flow velocity was measured by Doppler ultrasound in an animal model (ewe) with similar blood flow characteristics in the lower limb as man and allowing access to the required invasive measurements for validation of the method (pressure and flow). Vascular resistances distal to the measuring point (femoral, for example) were assessed using the resistance index R = D/S, S being the peak systolic deflection and D that of diastolic reflux of the Doppler spectral analysis of flow in the femoral artery. The values and variations of this resistance index were compared with the vascular resistances calculated from measurements of pressure and flow at the point of Doppler sampling and expressed in mmHg/ml/min. Femoral flow was measured by Doppler ultrasound (Doppler-echo), and mean pressure by an arterial catheter introduced into the abdominal aorta. Compression of the lower limb veins induced a venous return resulting in a reduction of cardiac output and femoral flow. During compression, femoral flow decreased by an average of 29% (p < 0.001) although mean pressure and heart rate did not change significantly. The femoral resistance index (Rf) increased by an average of 37.5% (p < 0.01) and vascular resistances increased by 45.9% (p < 0.01). Injection of 1 mg adrenaline induced peripheral vasoconstriction with an increase in blood pressure and a decrease in heart rate and femoral flow.(ABSTRACT TRUNCATED AT 250 WORDS).

The scale of hydrothermal circulation of the Iheya-North field inferred from intensive heat flow measurements and ocean drilling

NASA Astrophysics Data System (ADS)

Masaki, Y.; Kinoshita, M.; Yamamoto, H.; Nakajima, R.; Kumagai, H.; Takai, K.

2014-12-01

Iheya-North hydrothermal field situated in the middle Okinawa trough backarc basin is one of the largest ongoing Kuroko deposits in the world. Active chimneys as well as diffuse ventings (maximum fluid temperature 311 °C) have been located and studied in detail through various geological and geophysical surveys. To clarify the spatial scale of the hydrothermal circulation system, intensive heat flow measurements were carried out and ~100 heat flow data in and around the field from 2002 to 2014. In 2010, Integrated Ocean Drilling Program (IODP) Expedition 331 was carried out, and subbottom temperature data were obtained around the hydrothermal sites. During the JAMSTEC R/V Kaiyo cruise, KY14-01 in 2014, Iheya-North "Natsu" and "Aki" hydrothermal fields were newly found. The Iheya-Noth "Natsu" and "Aki" sites are located 1.2 km and 2.6 km south from the Iheya-North original site, respectively, and the maximum venting fluid temperature was 317 °C. We obtained one heat flow data at the "Aki" site. The value was 17 W/m2. Currently, the relationship between these hydrothermal sites are not well known. Three distinct zones are identified by heat flow values within 3 km from the active hydrothermal field. They are high-heat flow zone (>1 W/m2; HHZ), moderate-heat-flow zone (1-0.1 W/m2; MHZ); and low-heat-flow zone (<0.1 W/m2; LHZ). With increasing distance east of the HHZ, heat flow gradually decreases towards MHZ and LHZ. In the LHZ, temperature at 37m below the seafloor (mbsf) was 6 °C, that is consistent with the surface low heat flow suggesting the recharge of seawater. However, between 70 and 90 mbsf, the coarser sediments were cored, and temperature increased from 25 °C to 40°C. The temperature was 905°C at 151 mbsf, which was measured with thermoseal strips. The low thermal gradient in the upper 40 m suggests downward fluid flow. We infer that a hydrothermal circulation in the scale of ~1.5 km horizontal vs. ~a few hundred meters vertical.

Wave number selection in the presence of noise: Experimental results

NASA Astrophysics Data System (ADS)

Zhilenko, Dmitry; Krivonosova, Olga; Gritsevich, Maria; Read, Peter

2018-05-01

In this study, we consider how the wave number selection in spherical Couette flow, in the transition to azimuthal waves after the first instability, occurs in the presence of noise. The outer sphere was held stationary, while the inner sphere rotational speed was increased linearly from a subcritical flow to a supercritical one. In a supercritical flow, one of two possible flow states, each with different azimuthal wave numbers, can appear depending upon the initial and final Reynolds numbers and the acceleration value. Noise perturbations were added by introducing small disturbances into the rotational speed signal. With an increasing noise amplitude, a change in the dominant wave number from m to m ± 1 was found to occur at the same initial and final Reynolds numbers and acceleration values. The flow velocity measurements were conducted by using laser Doppler anemometry. Using these results, the role of noise as well as the behaviour of the amplitudes of the competing modes in their stages of damping and growth were determined.

Design and Implementation of Automatic Air Flow Rate Control System

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

A site-specific slurry application technique on grassland and on arable crops.

PubMed

Schellberg, Jürgen; Lock, Reiner

2009-01-01

There is evidence that unequal slurry application on agricultural land contributes to N losses to the environment. Heterogeneity within fields demands adequate response by means of variable rate application. A technique is presented which allows site-specific application of slurry on grassland and arable land based on pre-defined application maps. The system contains a valve controlling flow rate by an on-board PC. During operation, flow rate is measured and scaled against set point values given in the application map together with the geographic position of the site. The systems worked sufficiently precise at a flow rate between 0 and 25 l s(-1) and an offset of actual slurry flow from set point values between 0.33 and 0.67 l s(-1). Long-term experimentation is required to test if site-specific application de facto reduces N surplus within fields and so significantly contributes to the unloading of N in agricultural areas.

Influence of flow-through and renewal exposures on the toxicity of copper to rainbow trout

USGS Publications Warehouse

Welsh, P.G.; Lipton, J.; Mebane, C.A.; Marr, J.C.A.

2008-01-01

We examined changes in water chemistry and copper (Cu) toxicity in three paired renewal and flow-through acute bioassays with rainbow trout (Oncorhynchus mykiss). Test exposure methodology influenced both exposure water chemistry and measured Cu toxicity. Ammonia and organic carbon concentrations were higher and the fraction of dissolved Cu lower in renewal tests than in paired flow-through tests. Cu toxicity was also lower in renewal tests; 96 h dissolved Cu LC50 values were 7-60% higher than LC50s from matching flow-through tests. LC50 values in both types of tests were related to dissolved organic carbon (DOC) concentrations in exposure tanks. Increases in organic carbon concentrations in renewal tests were associated with reduced Cu toxicity, likely as a result of the lower bioavailability of Cu-organic carbon complexes. The biotic ligand model of acute Cu toxicity tended to underpredict toxicity in the presence of DOC. Model fits between predicted and observed toxicity were improved by assuming that only 50% of the measured DOC was reactive, and that this reactive fraction was present as fulvic acid. ?? 2007 Elsevier Inc. All rights reserved.

Forced Convection Heat Transfer of Subcooled Liquid Nitrogen in Horizontal Tube

NASA Astrophysics Data System (ADS)

Tatsumoto, H.; Shirai, Y.; Hata, K.; Kato, T.; Shiotsu, M.

2008-03-01

The knowledge of forced convection heat transfer of liquid hydrogen is important for the cooling design of a HTS superconducting magnet and a cold neutron moderator material. An experimental apparatus that could obtain forced flow without a pump was developed. As a first step of the study, the forced flow heat transfer of subcooled liquid nitrogen in a horizontal tube, instead of liquid hydrogen, was measured for the pressures ranging from 0.3 to 2.5 MPa. The inlet temperature was varied from 78 K to around its saturation temperature. The flow velocities were varied from 0.1 to 7 m/s. The heat transfer coefficients in the non-boiling region and the departure from nucleate boiling (DNB) heat fluxes were higher for higher flow velocity and higher subcooling. The measured values of Nu/Pr0.4 in the non-boiling region were proportional to Reynolds number (Re) to the power of 0.8. With a decrease in Re, Nu/Pr0.4 approached a constant value corresponding to that in a pool of liquid nitrogen. The correlation of DNB heat flux was derived that can describe the experimental data within ±15% difference.

Segmental microvascular permeability in ischemia-reperfusion injury in rat lung.

PubMed

Khimenko, P L; Taylor, A E

1999-06-01

Segmental microvascular permeabilities were measured using pre- and postalveolar vessel capillary filtration coefficient (Kfc) values (ml. min-1. cmH2O-1. 100 g-1) in isolated rat lungs subjected to ischemia-reperfusion (I/R). Total Kfc values measured in flowing and nonflowing lungs were highly correlated (r = 0.98, P < 0.0001). Kfc values were then measured in another group of lungs under no-flow conditions when airway pressure was increased to 20 cmH2O and either the arterial or venous pressure was elevated to 7-8 cmH2O to measure the prealveolar and postalveolar Kfc values. Control total and postalveolar Kfc values were 0.0225 +/- 0.001 and 0.0219 +/- 0.001 ml. min-1. cmH2O-1. 100 g-1, respectively, and the prealveolar permeability was extremely small (0.00003 +/- 0.00005 ml. min-1. cmH2O-1. 100 g-1). Kfc values were again made in nonflowing lungs that had been subjected to 45 min of ischemia followed by 30 min of reperfusion. After I/R, the total membrane Kfc increased 10-fold to 0.2597 +/- 0.006 ml. min-1. cmH2O-1. 100 g-1, the prealveolar Kfc increased to 0.0677 +/- 0.003 ml. min-1. cmH2O-1. 100 g-1, and the postalveolar Kfc increased to 0.1354 +/- 0.008 ml. min-1. cmH2O-1. 100 g-1 (P < 0.05 for all I/R values). These data indicate that normal solvent microvascular permeability was predominantly postalveolar, and after I/R damage, the postalveolar (venular) permeability comprised 52% of the total, whereas the prealveolar and alveolar vessels comprised only 27 and 23%, respectively, of the total Kfc.

Fluid mechanics experiments in oscillatory flow. Volume 1: Report

NASA Technical Reports Server (NTRS)

Seume, J.; Friedman, G.; Simon, T. W.

1992-01-01

Results of a fluid mechanics measurement program in oscillating flow within a circular duct are presented. The program began with a survey of transition behavior over a range of oscillation frequency and magnitude and continued with a detailed study at a single operating point. Such measurements were made in support of Stirling engine development. Values of three dimensionless parameters, Re(sub max), Re(sub w), and A(sub R), embody the velocity amplitude, frequency of oscillation and mean fluid displacement of the cycle, respectively. Measurements were first made over a range of these parameters which included operating points of all Stirling engines. Next, a case was studied with values of these parameters that are representative of the heat exchanger tubes in the heater section of NASA's Stirling cycle Space Power Research Engine (SPRE). Measurements were taken of the axial and radial components of ensemble-averaged velocity and rms-velocity fluctuation and the dominant Reynolds shear stress, at various radial positions for each of four axial stations. In each run, transition from laminar to turbulent flow, and its reverse, were identified and sufficient data was gathered to propose the transition mechanism. Models of laminar and turbulent boundary layers were used to process the data into wall coordinates and to evaluate skin friction coefficients. Such data aids in validating computational models and is useful in comparing oscillatory flow characteristics to those of fully-developed steady flow. Data were taken with a contoured entry to each end of the test section and with flush square inlets so that the effects of test section inlet geometry on transition and turbulence are documented. Volume 1 contains the text of the report including figures and supporting appendices. Volume 2 contains data reduction program listings and tabulated data (including its graphical presentation).

Accuracy of Oxygen Flow Delivered by Compressed-Gas Cylinders in Hospital and Prehospital Emergency Care.

PubMed

Duprez, Frédéric; Michotte, Jean Bernard; Cuvelier, Gregory; Legrand, Alexandre; Mashayekhi, Sharam; Reychler, Gregory

2018-03-01

Oxygen cylinders are widely used both in hospital and prehospital care. Excessive or inappropriate F IO 2 may be critical for patients with hypercapnia or hypoxia. Moreover, over-oxygenation could be deleterious in ischemic disorders. Supplemental oxygen from oxygen cylinder should therefore be delivered accurately. The aim of this study was to assess the accuracy of oxygen flows for oxygen cylinder in hospital and prehospital care. A prospective trial was conducted to evaluate accuracy of delivered oxygen flows (2, 4, 6, 9 and 12 L/min) for different oxygen cylinder ready for use in different hospital departments. Delivered flows were analyzed randomly using a calibrated thermal mass flow meter. Two types of oxygen cylinder were evaluated: 78 oxygen cylinder with a single-stage regulator and 70 oxygen cylinder with a dual-stage regulator. Delivered flows were compared to the required oxygen flow. The residual pressure value for each oxygen cylinder was considered. A coefficient of variation was calculated to compare the variability of the delivered flow between the two types of oxygen cylinder. The median values of delivered flows were all ≥ 100% of the required flow for single stage (range 100-109%) and < 100% of required flow for dual stage (range 95-97%). The median values of the delivered flow differed between single and dual stage. It was found that single stage is significantly higher than dual stage ( P = .01). At low flow, the dispersion of the measures for single stage was higher than with a high oxygen flow. Delivered flow differences were also found between low and high residual pressures, but only with single stage ( P = .02). The residual pressure for both oxygen cylinders (no. = 148) ranged from 73 to 2,900 pounds per square inch, and no significant difference was observed between the 2 types ( P = .86). The calculated coefficient of variation ranged from 7% (±1%) for dual stage to 8% (±2%) for single stage. This study shows good accuracy of oxygen flow delivered via oxygen cylinders. This accuracy was higher with dual stage. Single stage was also accurate, however, at low flow this accuracy is slightly less. Moreover, with single stage, when residual pressure decreases, the median value of delivered flow decreased. Copyright © 2018 by Daedalus Enterprises.

Oscillating-Flow Regenerator Test Rig: Hardware and Theory With Derived Correlations for Screens and Felts

NASA Technical Reports Server (NTRS)

Gedeon, D.; Wood, J. G.

1996-01-01

A number of wire mesh and metal felt test samples, with a range of porosities, yield generic correlations for friction factor, Nusselt number, enhanced axial conduction ratio, and overall heat flux ratio. This information is directed primarily toward stirling cycle regenerator modelers, but will be of use to anyone seeking to better model fluid flow through these porous materials. Behind these results lies an oscillating-flow test rig, which measures pumping dissipation and thermal energy transport in sample matrices, and several stages of data-reduction software, which correlate instantaneous values for the above dimensionless groups. Within the software, theoretical model reduces instantaneous quantifies from cycle-averaged measurables using standard parameter estimation techniques.

A study of the round jet/plane wall flow field

NASA Technical Reports Server (NTRS)

Foss, J. F.; Kleis, S. J.

1971-01-01

Impingement angles, between the axisymmetric jet axis and the plane wall, from zero to 15 degrees have been examined for nozzle heights of 0.75, 1.0, 1.5 and 2.0 diameters and for: (1) a fully developed pipe flow, and (2) a relatively uniform exit velocity condition. Velocity measurements have been used to define isotach contours and to determine mass, momentum and energy flux values for the near field (within five diameters) of the jet. Surface pressure measurements have been used to define surface pressure forces and jet centerline trajectories. The geometric and flow conditions examined and the interpretation of the results have been motivated by the externally blown flap STOL aircraft application.

Sweat Rate Prediction Equations for Outdoor Exercise with Transient Solar Radiation

DTIC Science & Technology

2012-01-01

AD] 15 Interchangeable variables gSL W/m2 Global solar load Direct weather station data; pyranometer values 25 Direct measurement from weather station ...Fanger equations 2, 4, 13, Direct or weather station values Rdif W Diffuse irradiance Rref W Reflected irradiance AD m2 Body surface area (BSA) from DuBois...assuming the given weather station uses standard meteorological measuring instru- ments. In the heat flow form expressed by Matthew et al. (25

Experimental investigation of turbulent flow through a circular-to-rectangular transition duct. Ph.D. Thesis - Washington Univ.

NASA Technical Reports Server (NTRS)

Davis, David O.

1991-01-01

Steady, incompressible, turbulent, swirl-free flow through a circular-to-rectangular transition duck was studied experimentally. The cross-sectional area remains the same at the exit as at the inlet, but varies through the transition section to a maximum value approximately 15 percent above the inlet value. The cross-sectional geometry everywhere along the duct is defined by the equation of a superellipse. Mean and turbulence data were accumulated utilizing pressure and hot-wire instrumentation at five stations along the test section. Data are presented for operating bulk Reynolds numbers of 88,000 and 390,000. Measured quantities include total and static pressure, the three components of the mean velocity vector, and the six components of the Reynolds stress tensor. In addition to the transition duct measurements, a hot-wire technique which relies on the sequential use of single rotatable normal and slant-wire probes was proposed. The technique is applicable for measurement of the total mean velocity vector and the complete Reynolds stress tensor when the primary flow is arbitrarily skewed relative to a plane which lies normal to the probe axis of rotation.

Final Scientific/Technical Report of Gas Hydrate Dynamics on the Alaskan Beaufort Continental Slope: Modeling and Field Characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hornbach, Matthew J; Colwell, Frederick S; Harris, Robert

Methane Hydrates, a solid form of methane and water, exist at high pressures and low temperatures, occurs on every continental margin on Earth, represents one of the largest reservoirs of carbon on the planet, and, if destabilized, may play an important role in both slope stability and climate change. For decades, researchers have studied methane hydrates with the hope of determining if methane hydrates are destabilizing, and if so, how this destabilization might impact slope stability and ocean/atmosphere carbon budgets. In the past ~5 years, it has become well established that the upper “feather-edge” of methane hydrate stability (intermediate watermore » depths of ~200-500 meters below sea level) represents an important frontier for methane hydrates stability research, as this zone is most susceptible to destabilization due to minor fluctuations in ocean temperature in space and time. The Arctic Ocean—one of the fastest warming regions on Earth—is perhaps the best place to study possible changes to methane hydrate stability due to ocean warming. To address the stability of methane hydrates at intermediate ocean depths, Southern Methodist University in partnership with Oregon State University and The United State Geological Survey at Woods Hole began investigating methane hydrate stability in intermediate water depths below both the US Beaufort Sea and the Atlantic Margin, from 2012-2017. The work was funded by the Department of Energy’s (DOE) National Energy Technology Laboratory (NETL). The key goal of the SMU component of this study was to collect the first ever heat flow data in the Beaufort Sea and compare measured shallow (probe-based1) heat flow values with deeper (BSR-derived2) heat flow values, and from this, determine whether hydrates were in thermal equilibrium. In September 2016, SMU/OSU collected the first ever heat flow measurements in the US Beaufort Sea. Despite poor weather and rough seas, the cruise was a success, with 116 heat flow measurements acquired across the margin, spanning 4 transects separated by more than 400 km. Useable heat flow data exists for 97% (113) of probe heat flow measurements, revealing a clear picture of regional heat flow across the basin. During the past 8 months since the cruise, SMU researchers have processed the heat flow and thermal conductivity measurements and compared results to deeper heat flow estimates obtained from seismic data. The analysis reveals clear, consistent trends: All probe heat flow measurements in depths greater than 800 mbsl are consistent with BSR-derived values; heat flow measurements obtained in water depths between ~250-750 mbsl are systematically lower than those estimated from BSRs; and heat flow estimates in water depths shallower than ~250 mbsl are systematically warmer than deeper estimates. The consistency between shallow (probe) and deep (BSR) heat flow measurements at depths greater than ~750 m where ocean temperature changes are minimal supports the premise that the hydrates consist primarily of methane and represent a valuable tool for estimating heat flow. The anomalous cooling trend observed in the upper 250 m is consistent with expected seasonal effects observed in shallow ocean buoy measurements in the arctic, when cold, less dense melting sea ice cools the upper 200 m of the ocean during the summer as ice melting occurs. The discrepancy in heat flow at intermediate water depths is best explained via recent intermediate ocean temperature warming, where long-term (annual or longer) warming intermediate ocean bottom waters result in an anomalously low heat flow in shallow heat flow measurements. Using the characteristic 1D time-length scale for diffusion, we estimate that ocean temperature warming began no later than ~1200 years ago but arguably much more recently as results are limited by seismic resolution. More importantly, our analysis indicates methane hydrate is destabilizing not only in the upper feather edge (200-500 mbsl) but at depths as great as 750 mbsl. The intermediate ocean warming rate supports previous studies suggesting geologically rapid warming (>0.1 deg C/decade) at intermediate ocean depths in the Beaufort Sea. Assuming no further changes or additional warming, our analysis indicates methane hydrates will destabilize at seafloor depths shallower than 750 mbsl in the Beaufort Sea within the next ~3000 years. 1 Probe outfitted with sensors inserted into the seafloor sediment 2 Bottom-simulating reflector (BSR) seismic data indicates presence of hydrate deposits« less

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

PubMed

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

2004-11-01

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

Skin microvascular flow during hypobaric exposure with and without a mechanical counter-pressure space suit glove

NASA Technical Reports Server (NTRS)

Tanaka, Kunihiko; Waldie, James; Steinbach, Gregory C.; Webb, Paul; Tourbier, Dietmar; Knudsen, Jeffrey; Jarvis, Christine W.; Hargens, Alan R.

2002-01-01

INTRODUCTION: Current space suits are rigid, gas-pressurized shells that protect astronauts from the vacuum of space. A tight elastic garment or mechanical-counter-pressure (MCP) suit generates pressure by compression and may have several advantages over current space suit technology. In this study, we investigated local microcirculatory effects produced with and without a prototype MCP glove. METHODS: The right hand of eight normal volunteers was studied at normal ambient pressure and during exposure to -50, -100 and -150 mm Hg with and without the MCP glove. Measurements included the pressure against the hand, skin microvascular flow, temperature on the dorsum of the hand, and middle finger girth. RESULTS: Without the glove, skin microvascular flow and finger girth significantly increased with negative pressure, and the skin temperature decreased compared with the control condition. The MCP glove generated approximately 200 mm Hg at the skin surface; all measured values remained at control levels during exposure to negative pressure. DISCUSSION: Without the glove, skin microvascular flow and finger girth increased with negative pressure, probably due to a blood shift toward the hand. The elastic compression of the material of the MCP glove generated pressure on the hand similar to that in current gas-pressurized space suit gloves. The MCP glove prevented the apparent blood shift and thus maintained baseline values of the measured variables despite exposure of the hand to negative pressure.

Effect of Oscillating Tabs on a Jet-in-Cross-Flow

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.

2003-01-01

A novel technique for active control of a jet-in-cross-flow is explored in this study. Two triangular tabs are placed at the 90 degree and 270 degree edges of the jet orifice, relative to the direction of the cross-flow. A slight asymmetry in the placement of the two tabs is reversed periodically. This causes a profound oscillation of the flow field that persists as far downstream as the measurements were permitted by the facility (100 orifice diameters). Parametric dependence of the unsteadiness and its impact on the flowfield has been investigated preliminarily. It is found that the effect becomes increasingly pronounced with increasing value of the momentum flux ratio (J). However, there is little or no effect at low values of J in the range, J less than 15. The effective frequencies of oscillation are low - more than an order of magnitude lower than that found with oscillatory blowing technique in previous studies. The flow mechanism apparently involves a direct perturbation of the counter-rotating streamwise vortex pair of the flow.

Regional Heat Flow Map and the Continental Thermal Isostasy Understanding of México

NASA Astrophysics Data System (ADS)

Espinoza-Ojeda, O. M.; Harris, R. N.

2014-12-01

The first heat flow values made in Mexico were reported by Von Herzen [Science, 1963] for the marine environment and Smith [EPSL, 1974] for the continent. Since that time the number of measurements has increased greatly but are mostly from oil and gas exploration and in and around geothermal areas. We have compiled published values of conductive heat flow for Mexico and the Gulf of California to generate a new regional heat flow map consisting of 261 values. In addition to those original values, published heat flow sources include, Lee and Henyey [JGR, 1975], Lawver and Williams [JGR, 1979] Smith et al. [JGR, 1979], Lachenbruch et al. [JGR, 1985], and Ziagos et al. [JGR, 1985]. Although the geographic distribution is uneven, heat flow data are present in each of the eight main tectonic provinces. Our new compilation indicates relatively high regional heat flow averages in the Gulf Extensional Province (n=114, 92±22 mW/m2) and Mexican Basin and Range (n=21, 82±20 mW/m2) and are consistent with geologic estimates of extension. Lower regional averages are found in the Baja California Microplate (n=91, 75±19 mW/m2), the Sierra Madre Occidental (n=9, 75±12 mW/m2), the Sierra Madre Oriental (n=4, 68±15 mW/m2) and Mesa Central (n=X 77±23 mW/m2). In contrast low and variable heat flow value characterize the forearc region of the Middle America Trench (n=6, 35±16 mW/m2). A higher mean heat flow is associated with the Trans-Mexican Volcanic Belt (n=6, 78±26 mW/m2). Continental elevation results from a combination of buoyancy (i.e. compositional and thermal) and geodynamic forces. We combine these regional heat flow values with estimates of crustal thickness and density for each tectonic province and compute the thermal and compositional buoyancy following the approach of Hasterok and Chapman [JGR, 2007a,b]. We find that within uncertainties most provinces lie near the theoretical isostatic relationship with the exception of the Mesa Central and Sierra Madre del Sur that are anomalously below and above the theoretical relationship, respectively.

Efficient Permeability Measurement and Numerical Simulation of the Resin Flow in Low Permeability Preform Fabricated by Automated Dry Fiber Placement

NASA Astrophysics Data System (ADS)

Agogue, Romain; Chebil, Naziha; Deleglise-Lagardere, Mylène; Beauchene, Pierre; Park, Chung Hae

2017-10-01

We propose a new experimental method using a Hassler cell and air injection to measure the permeability of fiber preform while avoiding a race tracking effect. This method was proven to be particularly efficient to measure very low through-thickness permeability of preform fabricated by automated dry fiber placement. To validate the reliability of the permeability measurement, the experiments of viscous liquid infusion into the preform with or without a distribution medium were performed. The experimental data of flow front advancement was compared with the numerical simulation result using the permeability values obtained by the Hassler cell permeability measurement set-up as well as by the liquid infusion experiments. To address the computational cost issue, the model for the equivalent permeability of distribution medium was employed in the numerical simulation of liquid flow. The new concept using air injection and Hassler cell for the fiber preform permeability measurement was shown to be reliable and efficient.

Statistical evaluation of the effects of fall and winter flows on the spring condition of rainbow and brown trout in the green river downstream of Flaming Gorge Dam.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magnusson, A. K.; LaGory, K. E.; Hayse, J. W.

2009-01-09

Flaming Gorge Dam, a hydroelectric facility operated by the Bureau of Reclamation (Reclamation), is located on the Green River in Daggett County, northeastern Utah. In recent years, single peak releases each day or steady flows have been the operational pattern during the winter period. A double-peak pattern (two flow peaks each day) was implemented during the winter of 2006-2007 by Reclamation. Because there is no recent history of double-peaking at Flaming Gorge Dam, the potential effects of double-peaking operations on the body condition of trout in the dam's tailwater are not known. A study plan was developed that identified researchmore » activities to evaluate potential effects from double-peaking operations during winter months. Along with other tasks, the study plan identified the need to conduct a statistical analysis of existing data on trout condition and macroinvertebrate abundance to evaluate potential effects of hydropower operations. This report presents the results of this analysis. We analyzed historical data to (1) describe temporal patterns and relationships among flows, benthic macroinvertebrate abundance, and condition of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) in the tailwaters of Flaming Gorge Dam and (2) to evaluate the degree to which flow characteristics (i.e., flow volumes and flow variability) and benthic macroinvertebrate abundance affect the condition of trout in this area. This information, together with further analyses of size-stratified trout data, may also serve as baseline data to which the effects of potential future double-peaking flows can be compared. The condition (length, weight and/or relative weight) of rainbow trout (Oncorhynchus mykiss) at two sites in the Green River downstream of Flaming Gorge Dam (Tailrace and Little Hole) and weight of brown trout (Salmo trutta) at the Little Hole site has been decreasing since 1990 while the abundance of brown trout has been increasing at the two sites. At the same time, flow variability in the river has decreased and the abundance of total benthic macroinvertebrates at the Tailrace site has increased. The condition of trout in spring (averaged across all sampled trout) was positively correlated with fall and winter flow variability (including within-day skewness, within-season skewness and/or change in flow between days) at both locations. No negative correlations between trout condition and any measure of flow variability were detected. The length and weight of rainbow trout at the Little Hole site were negatively correlated with increasing fall and winter flow volume. The condition of brown trout at Little Hole and the condition of brown and rainbow trout at Tailrace were not correlated with flow volume. Macroinvertebrate variables during October were either positively correlated or not correlated with measures of trout condition at the Tailrace and Little Hole sites. With the exception of a positive correlation between taxa richness of macroinvertebrates in January and the relative weight of brown trout at Tailrace, the macroinvertebrate variables during January and April were either not correlated or negatively correlated with measures of trout condition. We hypothesize that high flow variability increased drift by dislodging benthic macroinvertebrates, and that the drift, in turn, resulted in mostly lower densities of benthic macroinvertebrates, which benefited the trout by giving them more feeding opportunities. This was supported by negative correlations between benthic macroinvertebrates and flow variability. Macroinvertebrate abundance (with the exception of ephemeropterans) was also negatively correlated with flow volume. The change in trout condition from fall to spring, as measured by the ratio of spring to fall relative weight, was evaluated to determine their usefulness as a standardized index to control for the initial condition of the fish as they enter the winter period. The ratio values were less correlated with the fall condition values than the spring condition values and did not show the same relationships to flows, to macroinvertebrates, or across years as the above-mentioned spring relative weight values. We found that the condition ratio of rainbow trout at Tailrace was positively correlated with within-day flow variability but was not correlated with flow volume, between-day-, or within-season flow variability. The condition ratios of rainbow trout at Little Hole and of both trout species at Tailrace were not correlated to any of the measured flow variables. The condition ratios of both trout species were positively correlated with the abundance of January benthic macroinvertebrates at the Little Hole site and with January dipterans (brown trout) or total coleopterans (rainbow trout) at the Tailrace site. The relationships among flows, macroinvertebrates, and trout condition were varied among species and locations.« less

Development of multiple-eye PIV using mirror array

NASA Astrophysics Data System (ADS)

Maekawa, Akiyoshi; Sakakibara, Jun

2018-06-01

In order to reduce particle image velocimetry measurement error, we manufactured an ellipsoidal polyhedral mirror and placed it between a camera and flow target to capture n images of identical particles from n (=80 maximum) different directions. The 3D particle positions were determined from the ensemble average of n C2 intersecting points of a pair of line-of-sight back-projected points from a particle found in any combination of two images in the n images. The method was then applied to a rigid-body rotating flow and a turbulent pipe flow. In the former measurement, bias error and random error fell in a range of  ±0.02 pixels and 0.02–0.05 pixels, respectively; additionally, random error decreased in proportion to . In the latter measurement, in which the measured value was compared to direct numerical simulation, bias error was reduced and random error also decreased in proportion to .

Carbon-dioxide flow measurement in geodynamically active area of West Bohemia

NASA Astrophysics Data System (ADS)

Vlcek, Josef; Fischer, Tomas; Heinicke, Jens

2016-04-01

Geodynamically active area of West Bohemia is interesting not only due to its earthquake swarms occurrence but also due to degassing flux of magmatic origin occurring in natural moffettes and mineral springs. While monitoring of earthquakes is done by a standard local seismic network, monitoring of amount of CO2 is at its initial stage. Despite lack of data, the 2014 earthquake swarm showed also very interesting increase in CO2 flow. This correlation with seismicity motivated us to develop robust and reliable methods of CO2 flow measurement, which would be sufficient to create denser monitoring network. Standard usage of gas-flowmeter for the purpose of gas flow measurement is dependent on the weather and device conditions, which makes the measurement instable in time and unreliable. Although gas-flowmeter is also accompanied with measurement of the gas pressure in the well to check flow rate value, reliability of this method is still low. This problematic behavior of the flow measurement was the reason to test new methods to measure CO2 amount - the first is based on measuring the density water with bubbles in the well by differential pressure gauge. The second one utilizes electric conductivity measurement to determine the density of bubbles in the water-gas mixture. Advantage of these methods is that their probes are directly in the well or moffette, where the concentration is measured. This approach is free of the influence of moving parts and assures the independence of measurements of environmental conditions. In this paper we show examples of obtained data series from selected sites and compare the trend of the curves, the mutual relations of the measured quantities and the influence of environmental conditions.

Hydraulic properties for interrill erosion on steep slopes using a portable rainfall simulator

NASA Astrophysics Data System (ADS)

Shin, Seung Sook; Hwang, Yoonhee; Deog Park, Sang; Yun, Minu; Park, Sangyeon

2017-04-01

The hydraulic parameters for sheet flow on steep slopes have been not frequently measured because the shallow flow depth and slow flow velocity are difficult to measure. In this study hydraulic values of sheet flow were analyzed to evaluate interrill erosion on steep slopes. A portable rainfall simulator was used to conduct interrill erosion test. The kinetic energy of rainfall simulator was obtained by disdrometer being capable of measuring the drop size distribution and velocity of falling raindrops. The sheet flow velocity was determined by the taken time for a dye transferring fixed points using video images. Surface runoff discharge and sediment yield increased with increase of rainfall intensity and kinetic energy and slope steepness. Especially sediment yield was strongly correlated with sheet flow velocity. The maximum velocity of sheet flow was 2.3cm/s under rainfall intensity of 126.8mm/h and slope steepness of 53.2%. The sheet flow was laminar and subcritical flow as the flow Reynolds number and Froude number are respectively the ranges of 10 22 and 0.05 0.25. The roughness coefficient (Manning's n) for sheet flow on steep slopes was relatively large compared to them on the gentle slope. Keywords: Sheet flow velocity; Rainfall simulator; Interrill erosion; Steep slope This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIP) (No. 2015R1C1A2A01055469).

Soil CO2 emissions as a proxy for heat and mass flow assessment, Taupō Volcanic Zone, New Zealand

USGS Publications Warehouse

Bloomberg, S.; Werner, Cynthia A.; Rissmann, C.F.; Mazot, A.; Horton, Travis B.; Gravley, D; Kennedy, B.; Oze, C

2014-01-01

The quantification of heat and mass flow between deep reservoirs and the surface is important for understanding magmatic and hydrothermal systems. Here, we use high-resolution measurement of carbon dioxide flux (φCO2) and heat flow at the surface to characterize the mass (CO2 and steam) and heat released to the atmosphere from two magma-hydrothermal systems. Our soil gas and heat flow surveys at Rotokawa and White Island in the Taupō Volcanic Zone, New Zealand, include over 3000 direct measurements of φCO2 and soil temperature and 60 carbon isotopic values on soil gases. Carbon dioxide flux was separated into background and magmatic/hydrothermal populations based on the measured values and isotopic characterization. Total CO2 emission rates (ΣCO2) of 441 ± 84 t d−1 and 124 ± 18 t d−1were calculated for Rotokawa (2.9 km2) and for the crater floor at White Island (0.3 km2), respectively. The total CO2 emissions differ from previously published values by +386 t d−1 at Rotokawa and +25 t d−1 at White Island, demonstrating that earlier research underestimated emissions by 700% (Rotokawa) and 25% (White Island). These differences suggest that soil CO2 emissions facilitate more robust estimates of the thermal energy and mass flux in geothermal systems than traditional approaches. Combining the magmatic/hydrothermal-sourced CO2 emission (constrained using stable isotopes) with reservoir H2O:CO2mass ratios and the enthalpy of evaporation, the surface expression of thermal energy release for the Rotokawa hydrothermal system (226 MWt) is 10 times greater than the White Island crater floor (22.5 MWt).

Local flow measurements at the inlet spike tip of a Mach 3 supersonic cruise airplane

NASA Technical Reports Server (NTRS)

Johnson, H. J.; Montoya, E. J.

1973-01-01

The flow field at the left inlet spike tip of a YF-12A airplane was examined using at 26 deg included angle conical flow sensor to obtain measurements at free-stream Mach numbers from 1.6 to 3.0. Local flow angularity, Mach number, impact pressure, and mass flow were determined and compared with free-stream values. Local flow changes occurred at the same time as free-stream changes. The local flow usually approached the spike centerline from the upper outboard side because of spike cant and toe-in. Free-stream Mach number influenced the local flow angularity; as Mach number increased above 2.2, local angle of attack increased and local sideslip angle decreased. Local Mach number was generally 3 percent less than free-stream Mach number. Impact-pressure ratio and mass flow ratio increased as free-stream Mach number increased above 2.2, indicating a beneficial forebody compression effect. No degradation of the spike tip instrumentation was observed after more than 40 flights in the high-speed thermal environment encountered by the airplane. The sensor is rugged, simple, and sensitive to small flow changes. It can provide accurate imputs necessary to control an inlet.

Comparison of two surface temperature measurement using thermocouples and infrared camera

NASA Astrophysics Data System (ADS)

Michalski, Dariusz; Strąk, Kinga; Piasecka, Magdalena

This paper compares two methods applied to measure surface temperatures at an experimental setup designed to analyse flow boiling heat transfer. The temperature measurements were performed in two parallel rectangular minichannels, both 1.7 mm deep, 16 mm wide and 180 mm long. The heating element for the fluid flowing in each minichannel was a thin foil made of Haynes-230. The two measurement methods employed to determine the surface temperature of the foil were: the contact method, which involved mounting thermocouples at several points in one minichannel, and the contactless method to study the other minichannel, where the results were provided with an infrared camera. Calculations were necessary to compare the temperature results. Two sets of measurement data obtained for different values of the heat flux were analysed using the basic statistical methods, the method error and the method accuracy. The experimental error and the method accuracy were taken into account. The comparative analysis showed that although the values and distributions of the surface temperatures obtained with the two methods were similar but both methods had certain limitations.

Effect of beam hardening on transmural myocardial perfusion quantification in myocardial CT imaging

NASA Astrophysics Data System (ADS)

Fahmi, Rachid; Eck, Brendan L.; Levi, Jacob; Fares, Anas; Wu, Hao; Vembar, Mani; Dhanantwari, Amar; Bezerra, Hiram G.; Wilson, David L.

2016-03-01

The detection of subendocardial ischemia exhibiting an abnormal transmural perfusion gradient (TPG) may help identify ischemic conditions due to micro-vascular dysfunction. We evaluated the effect of beam hardening (BH) artifacts on TPG quantification using myocardial CT perfusion (CTP). We used a prototype spectral detector CT scanner (Philips Healthcare) to acquire dynamic myocardial CTP scans in a porcine ischemia model with partial occlusion of the left anterior descending (LAD) coronary artery guided by pressure wire-derived fractional flow reserve (FFR) measurements. Conventional 120 kVp and 70 keV projection-based mono-energetic images were reconstructed from the same projection data and used to compute myocardial blood flow (MBF) using the Johnson-Wilson model. Under moderate LAD occlusion (FFR~0.7), we used three 5 mm short axis slices and divided the myocardium into three LAD segments and three remote segments. For each slice and each segment, we characterized TPG as the mean "endo-to-epi" transmural flow ratio (TFR). BH-induced hypoenhancement on the ischemic anterior wall at 120 kVp resulted in significantly lower mean TFR value as compared to the 70 keV TFR value (0.29+/-0.01 vs. 0.55+/-0.01 p<1e-05). No significant difference was measured between 120 kVp and 70 keV mean TFR values on segments moderately affected or unaffected by BH. In the entire ischemic LAD territory, 120 kVp mean endocardial flow was significantly reduced as compared to mean epicardial flow (15.80+/-10.98 vs. 40.85+/-23.44 ml/min/100g; p<1e-04). At 70 keV, BH was effectively minimized resulting in mean endocardial MBF of 40.85+/-15.3407 ml/min/100g vs. 74.09+/-5.07 ml/min/100g (p=0.0054) in the epicardium. We also found that BH artifact in the conventional 120 kVp images resulted in falsely reduced MBF measurements even under non-ischemic conditions.

Stereoscopic particle image velocimetry investigations of the mixed convection exchange flow through a horizontal vent

NASA Astrophysics Data System (ADS)

Varrall, Kevin; Pretrel, Hugues; Vaux, Samuel; Vauquelin, Olivier

2017-10-01

The exchange flow through a horizontal vent linking two compartments (one above the other) is studied experimentally. This exchange is here governed by both the buoyant natural effect due to the temperature difference of the fluids in both compartments, and the effect of a (forced) mechanical ventilation applied in the lower compartment. Such a configuration leads to uni- or bi-directional flows through the vent. In the experiments, buoyancy is induced in the lower compartment thanks to an electrical resistor. The forced ventilation is applied in exhaust or supply modes and three different values of the vent area. To estimate both velocity fields and flow rates at the vent, measurements are realized at thermal steady state, flush the vent in the upper compartment using stereoscopic particle image velocimetry (SPIV), which is original for this kind of flow. The SPIV measurements allows the area occupied by both upward and downward flows to be determined.

Systematic Heat Flow Measurements Across the Wagner Basin, Northern Gulf of California

NASA Astrophysics Data System (ADS)

Neumann, F.; Negrete-Aranda, R.; Harris, R. N.; Contreras, J.; Sclater, J. G.; Gonzalez-Fernandez, A.

2017-12-01

A primary control on the geodynamics of rifting is the thermal regime. To better understand the geodynamics of rifting in the northern Gulf of California we systematically measured heat-flow across the Wagner Basin, a tectonically active basin that lies near the southern terminus of the Cerro Prieto fault. Seismic reflection profiles show sediment in excess of 5 s two-way travel time, implying a sediment thickness of > 7 km. The heat flow profile is 40 km long, has a nominal measurement spacing of 1 km, and is collocated with a seismic reflection profile. Heat flow measurements were made with a 6.5-m violin-bow probe. Most measurements are of good quality in that the probe fully penetrated sediments and measurements were stable enough to invert for heat flow and thermal properties. We have estimated corrections for environmental perturbations due to changes in bottom water temperature and sedimentation. The mean and standard deviation of heat flow across the western, central, and eastern parts of the basin are 220±60, 99±14, 1058±519 mW m-2, respectively. Corrections for sedimentation would increase measured heat flow across the central part of basin by 40 to 60%. We interpret the relatively high heat flow and large variability on the western and eastern flanks in terms of upward fluid flow at depth below the seafloor, whereas the lower and more consistent values across the central part of the basin are suggestive of conductive heat transfer. Based on an observed fault depth of 1.75 km we estimated the maximum Darcy velocities through the western and eastern flanks as 3 and 10 cm yr-1, respectively. Heat flow across the central basin is consistent with gabbroic underplating at a depth of 15 km and suggests that continental rupture here has not gone to completion.

Carbon Isotope Composition as an Indicator of DOC Sources to a Stream During Events in a Temperate Forested Catchment

NASA Astrophysics Data System (ADS)

Doctor, D. H.; Sebestyen, S. D.; Aiken, G. R.; Shanley, J. B.; Kendall, C.; Boyer, E. W.

2006-12-01

Increased DOC flux in streams and rivers is commonly observed during high runoff regimes, however DOC concentrations alone do not provide information about multiple sources or pathways of DOC to streams. In an effort to gain this information, we measured DOC concentrations and stable carbon isotope composition (δ13C-DOC) on samples collected at high-frequency during events at Sleepers River Research Watershed in Vermont, USA. During snowmelt and storm events, peaks in stream DOC concentration (up to 10.5 mg/L) were coincident with peaks in flow. Stream water δ13C-DOC measurements ranged between -23.7‰ and - 28.9‰ and indicated changing sources of DOC during events; the highest δ13C-DOC values occurred consistently at the lowest flows, and the lowest δ13C-DOC values occurred with peaks in discharge. Water samples collected from shallow wells and stacked soil lysimeters showed the highest DOC concentrations in the most shallow (<0.5 m) lysimeter waters, and the lowest concentrations in the deeper (>1.5 m) well waters. Wells and lysimeters exhibited a range of δ13C-DOC values similar to those observed in the stream; however, samples collected from shallow horizons at nested wells and lysimeters consistently showed lower δ13C-DOC values than those from greater depths. Maple leaf litter collected from across the watershed provided an end-member of fresh organic material, with average δ13C composition of -31.3±0.7‰ (n=57), which is lower than the lowest measured DOC values in any of the stream, well, or lysimeter waters. A subset of stream waters were fractionated onto XAD4 and XAD8 resins; the hydrophobic acid fraction (XAD8) had consistently lower δ13C values than the transphilic acid fraction (XAD4), and both of these were lower than those of the bulk DOC. Samples with lower δ13C-DOC values also exhibited higher SUVA-254 values, i.e. greater aromaticity. Thus, lower δ13C-DOC values are interpreted as an indicator of relatively "fresh", more aromatic and more biologically labile material while higher δ13C-DOC values indicate relatively more degraded material. Since lower δ13C-DOC values were observed in the shallowest well and lysimeter waters and in stream water during periods of highest DOC flux, we surmise that fresh DOC is mobilized to the stream along relatively shallow flowpaths during high flows, and that a second source of more degraded DOC supplies background concentrations to the stream at lower flows.

Design of a High Viscosity Couette Flow Facility for Patterned Surface Drag Measurements

NASA Astrophysics Data System (ADS)

Johnson, Tyler; Lang, Amy

2009-11-01

Direct drag measurements can be difficult to obtain with low viscosity fluids such as air or water. In this facility, mineral oil is used as the working fluid to increase the shear stress across the surface of experimental models. A mounted conveyor creates a flow within a plexiglass tank. The experimental model of a flat or patterned surface is suspended above a moving belt. Within the gap between the model and moving belt a Couette flow with a linear velocity profile is created. PIV measurements are used to determine the exact velocities and the Reynolds numbers for each experiment. The model is suspended by bars that connect to the pillow block housing of each bearing. Drag is measured by a force gauge connected to linear roller bearings that slide along steel rods. The patterned surfaces, initially consisting of 2-D cavities, are embedded in a plexiglass plate so as to keep the total surface area constant for each experiment. First, the drag across a flat plate is measured and compared to theoretical values for laminar Couette flow. The drag for patterned surfaces is then measured and compared to a flat plate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, R.V.

This book reports on remedial measures for gas wells and new methods for calculating the position of the stabilized performance curves for gas wells as well as the heating value for natural gases from compositional analyses. In addition, the author includes problem solutions in an appendix and a section showing the relation between the conventional empirical equation and the theoretical performance equation of A.S. Odeh. The author successfully bridges the gap between the results of empirical testing and the theory of unsteady-state flow in porous media. It strengthens the bond between conventional reservoir engineering practices and understanding gas well behavior.more » Problems listed at the end of each chapter are excellent exercises for practitioners. This book provides information on: Natural Gas Engineering; Properties of natural gas; Application of gas laws to reservoir engineering; Gas measurement; Flow of natural gas in circular pipe and annular conductors; Flow of gas in porous media (a review); Gas well testing; Unsteady-state flow behavior of gas wells; Production forecasting for gas wells; Production decline curves for gas wells; Sizing flow strings for gas wells; Remedial measures for gas wells; Gas sales contracts; and appendices on Compressibility for natural gas, Gas measurement factors, SI metric conversion factors, and Solutions to problems.« less

Improving Ecological Response Monitoring of Environmental Flows

NASA Astrophysics Data System (ADS)

King, Alison J.; Gawne, Ben; Beesley, Leah; Koehn, John D.; Nielsen, Daryl L.; Price, Amina

2015-05-01

Environmental flows are now an important restoration technique in flow-degraded rivers, and with the increasing public scrutiny of their effectiveness and value, the importance of undertaking scientifically robust monitoring is now even more critical. Many existing environmental flow monitoring programs have poorly defined objectives, nonjustified indicator choices, weak experimental designs, poor statistical strength, and often focus on outcomes from a single event. These negative attributes make them difficult to learn from. We provide practical recommendations that aim to improve the performance, scientific robustness, and defensibility of environmental flow monitoring programs. We draw on the literature and knowledge gained from working with stakeholders and managers to design, implement, and monitor a range of environmental flow types. We recommend that (1) environmental flow monitoring programs should be implemented within an adaptive management framework; (2) objectives of environmental flow programs should be well defined, attainable, and based on an agreed conceptual understanding of the system; (3) program and intervention targets should be attainable, measurable, and inform program objectives; (4) intervention monitoring programs should improve our understanding of flow-ecological responses and related conceptual models; (5) indicator selection should be based on conceptual models, objectives, and prioritization approaches; (6) appropriate monitoring designs and statistical tools should be used to measure and determine ecological response; (7) responses should be measured within timeframes that are relevant to the indicator(s); (8) watering events should be treated as replicates of a larger experiment; (9) environmental flow outcomes should be reported using a standard suite of metadata. Incorporating these attributes into future monitoring programs should ensure their outcomes are transferable and measured with high scientific credibility.

Measurement Of Crossflow Vortex Structure

NASA Technical Reports Server (NTRS)

Maddalon, Dal V.; Agarwal, Navel K.

1994-01-01

Method developed for measuring wavelengths of crossflow vortices by using surface-mounted, microthin, multielement hot-film sensors. Provides direct and true value of wavelength of crossflow vortices at various spanwise locations without localized flow disturbances. Attainment of laminar airflow on aircraft wings has significant potential for reducing drag and increasing fuel efficiency.

Field calibration of submerged sluice gates in irrigation canals

USDA-ARS?s Scientific Manuscript database

Four rectangular sluice gates were calibrated for submerged-flow conditions using nearly 16,000 field-measured data points on Canal B of the B-XII irrigation scheme in Lebrija, Spain. Water depth and gate opening values were measured using acoustic sensors at each of the gate structures, and the dat...

A comparison of measured and predicted test flow in an expansion tube with air and oxygen test gases

NASA Technical Reports Server (NTRS)

Aaggard, K. V.; Goad, W. K.

1975-01-01

Simultaneous time-resolved measurements of temperature, density, pitot pressure, and wall pressure in both air and O2 test gases were obtained in the Langley pilot model expansion tube. These tests show nonequilibrium chemical and vibrational relaxation significantly affect the test-flow condition. The use of an electromagnetic device to preopen the secondary diaphragm before the arrival of the primary shock wave resulted in an improvement in the agreement between the measured pitot pressure and the value inferred from measured density and interface velocity. Boundary-layer splitter plates used to reduce the wall boundary layer show that this disagreement in the measured and inferred pitot pressures is not a result of boundary-layer effects.

The characterisation and application of a pulsed neodymium YAG laser DGV system to a time-varying high-speed flow

NASA Astrophysics Data System (ADS)

Thorpe, S. J.; Quinlan, N.; Ainsworth, R. W.

2000-10-01

Doppler Global Velocimetry (DGV) is a whole-field measurement technique which has attracted significant interest from the fluid-flow research community since its introduction in 1991. Practical implementations of the methodology have focused on two principal laser light sources: the argon ion laser, applied to steady state or slowly varying flows; and the pulsed neodymium YAG laser for the measurement of instantaneous velocity fields. However, the emphasis in the published literature has been very much on research using the argon laser. This paper reports the application of a Q-switched, injection-seeded neodymium YAG laser to the proven Oxford DGV system, and the use of this combination in a short duration unsteady high-speed flow. The pertinent characteristics of the apparatus are described, and the impact of these on the integrity of the resulting velocity measurements is presented. Adaptations to the commercial laser system that make it suitable for application to the measurement of transient high-speed flows are described. Finally, the application of this system to a short duration unsteady flow is described. This application is based on the flow found in a new type of transdermal drug delivery device, where particles of the drug material are projected at high speed through the skin. Whole-field velocities are recorded, and values as high as 800 m/ s are evident.

Application of a Short Intracellular pH Method to Flow Cytometry for Determining Saccharomyces cerevisiae Vitality ▿

PubMed Central

Weigert, Claudia; Steffler, Fabian; Kurz, Tomas; Shellhammer, Thomas H.; Methner, Frank-Jürgen

2009-01-01

The measurement of yeast's intracellular pH (ICP) is a proven method for determining yeast vitality. Vitality describes the condition or health of viable cells as opposed to viability, which defines living versus dead cells. In contrast to fluorescence photometric measurements, which show only average ICP values of a population, flow cytometry allows the presentation of an ICP distribution. By examining six repeated propagations with three separate growth phases (lag, exponential, and stationary), the ICP method previously established for photometry was transferred successfully to flow cytometry by using the pH-dependent fluorescent probe 5,6-carboxyfluorescein. The correlation between the two methods was good (r2 = 0.898, n = 18). With both methods it is possible to track the course of growth phases. Although photometry did not yield significant differences between exponentially and stationary phases (P = 0.433), ICP via flow cytometry did (P = 0.012). Yeast in an exponential phase has a unimodal ICP distribution, reflective of a homogeneous population; however, yeast in a stationary phase displays a broader ICP distribution, and subpopulations could be defined by using the flow cytometry method. In conclusion, flow cytometry yielded specific evidence of the heterogeneity in vitality of a yeast population as measured via ICP. In contrast to photometry, flow cytometry increases information about the yeast population's vitality via a short measurement, which is suitable for routine analysis. PMID:19581482

Fluid flow dynamics in MAS systems

NASA Astrophysics Data System (ADS)

Wilhelm, Dirk; Purea, Armin; Engelke, Frank

2015-08-01

The turbine system and the radial bearing of a high performance magic angle spinning (MAS) probe with 1.3 mm-rotor diameter has been analyzed for spinning rates up to 67 kHz. We focused mainly on the fluid flow properties of the MAS system. Therefore, computational fluid dynamics (CFD) simulations and fluid measurements of the turbine and the radial bearings have been performed. CFD simulation and measurement results of the 1.3 mm-MAS rotor system show relatively low efficiency (about 25%) compared to standard turbo machines outside the realm of MAS. However, in particular, MAS turbines are mainly optimized for speed and stability instead of efficiency. We have compared MAS systems for rotor diameter of 1.3-7 mm converted to dimensionless values with classical turbomachinery systems showing that the operation parameters (rotor diameter, inlet mass flow, spinning rate) are in the favorable range. This dimensionless analysis also supports radial turbines for low speed MAS probes and diagonal turbines for high speed MAS probes. Consequently, a change from Pelton type MAS turbines to diagonal turbines might be worth considering for high speed applications. CFD simulations of the radial bearings have been compared with basic theoretical values proposing considerably smaller frictional loss values. The discrepancies might be due to the simple linear flow profile employed for the theoretical model. Frictional losses generated inside the radial bearings result in undesired heat-up of the rotor. The rotor surface temperature distribution computed by CFD simulations show a large temperature gradient over the rotor.

Base-flow characteristics of streams in the Valley and Ridge, Blue Ridge, and Piedmont physiographic provinces of Virginia

USGS Publications Warehouse

Nelms, D.L.; Harlow, G.E.; Hayes, Donald C.

1995-01-01

Growth within the Valley and Ridge, Blue Ridge, and Piedmont Physiographic Provinces of Virginia has focussed concern about allocation of surface-water flow and increased demands on the ground-water resources. The purpose of this report is to (1) describe the base-flow characteristics of streams, (2) identify regional differences in these flow characteristics, and (3) describe, if possible, the potential surface-water and ground-water yields of basins on the basis of the base-flow character- istics. Base-flow characteristics are presented for streams in the Valley and Ridge, Blue Ridge, and Piedmont Physiographic Provinces of Virginia. The provinces are separated into five regions: (1) Valley and Ridge, (2) Blue Ridge, (3) Piedmont/Blue Ridge transition, (4) Piedmont northern, and (5) Piedmont southern. Different flow statistics, which represent streamflows predominantly comprised of base flow, were determined for 217 continuous-record streamflow-gaging stations from historical mean daily discharge and for 192 partial-record streamflow-gaging stations by means of correlation of discharge measurements. Variability of base flow is represented by a duration ratio developed during this investigation. Effective recharge rates were also calculated. Median values for the different flow statistics range from 0.05 cubic foot per second per square mile for the 90-percent discharge on the streamflow-duration curve to 0.61 cubic foot per second per square mile for mean base flow. An excellent estimator of mean base flow for the Piedmont/Blue Ridge transition region and Piedmont southern region is the 50-percent discharge on the streamflow-duration curve, but tends to under- estimate mean base flow for the remaining regions. The base-flow variability index ranges from 0.07 to 2.27, with a median value of 0.55. Effective recharge rates range from 0.07 to 33.07 inches per year, with a median value of 8.32 inches per year. Differences in the base-flow characteristics exist between regions. The median discharges for the Valley and Ridge, Blue Ridge, and Piedmont/Blue Ridge transition regions are higher than those for the Piedmont regions. Results from statistical analysis indicate that the regions can be ranked in terms of base-flow characteristics from highest to lowest as follows: (1) Piedmont/Blue Ridge transition, (2) Valley and Ridge and Blue Ridge, (3) Piedmont southern, and (4) Piedmont northern. The flow statistics are consistently higher and the values for base-flow variability are lower for basins within the Piedmont/Blue Ridge transition region relative to those from the other regions, whereas the basins within the Piedmont northern region show the opposite pattern. The group rankings of the base-flow characteristics were used to designate the potential surface-water yield for the regions. In addition, an approach developed for this investigation assigns a rank for potential surface- water yield to a basin according to the quartiles in which the values for the base-flow character- istics are located. Both procedures indicate that the Valley and Ridge, Blue Ridge, and Piedmont/Blue Ridge transition regions have moderate-to-high potential surface-water yield and the Piedmont regions have low-to-moderate potential surface- water yield. In order to indicate potential ground-water yield from base-flow characteristics, aquifer properties for 51 streamflow-gaging stations with continuous record of streamflow data were determined by methods that use streamflow records and basin characteristics. Areal diffusivity ranges from 17,100 to 88,400 feet squared per day, with a median value of 38,400 feet squared per day. Areal transmissivity ranges from 63 to 830 feet squared per day, with a median value of 270 feet squared per day. Storage coefficients, which were estimated by dividing areal transmissivity by areal diffusivity, range from approximately 0.001 to 0.019 (dimensionless), with a median value of 0.007. The median value for areal diffus

Revisiting the accuracy of peak flow meters: a double-blind study using formal methods of agreement.

PubMed

Nazir, Z; Razaq, S; Mir, S; Anwar, M; Al Mawlawi, G; Sajad, M; Shehab, A; Taylor, R S

2005-05-01

There is widespread use of peak flow meters in both hospitals and general practice. Previous studies to assess peak flow meter accuracy have shown significant differences in the values obtained from different meters. However, many of these studies did not use human subjects for peak flow measurements and did not compare meters of varying usage. In this study human subjects have been used with meters of varying usage. Participants were tested using two new (meters A and C) and one old peak flow meter (meter B) in random order. The study was double-blinded. Participants were recruited from the university campus. Four hundred and nine individuals participated. The difference between peak flow means of A and B was -9.93 l/min (95% CI: -12.37 to -7.48, P<0.0001). The difference between peak flow means of B and C was 20.08 l/min (95% CI: 17.85-22.29, P<0.0001). The difference between peak flow means of A and C was 10.15 l/min (95% CI: 7.68-12.61, P<0.0001). There was a significant difference between the values obtained from the new and old peak flow meters and also between the two new peak flow meters. We conclude that there is need for caution in interchangeably using flow meters in clinical practice.

Flow resistance dynamics in step‐pool channels: 2. Partitioning between grain, spill, and woody debris resistance

USGS Publications Warehouse

Wilcox, Andrew C.; Nelson, Jonathan M.; Wohl, Ellen E.

2006-01-01

In step‐pool stream channels, flow resistance is created primarily by bed sediments, spill over step‐pool bed forms, and large woody debris (LWD). In order to measure resistance partitioning between grains, steps, and LWD in step‐pool channels we completed laboratory flume runs in which total resistance was measured with and without grains and steps, with various LWD configurations, and at multiple slopes and discharges. Tests of additive approaches to resistance partitioning found that partitioning estimates are highly sensitive to the order in which components are calculated and that such approaches inflate the values of difficult‐to‐measure components that are calculated by subtraction from measured components. This effect is especially significant where interactions between roughness features create synergistic increases in resistance such that total resistance measured for combinations of resistance components greatly exceeds the sum of those components measured separately. LWD contributes large proportions of total resistance by creating form drag on individual pieces and by increasing the spill resistance effect of steps. The combined effect of LWD and spill over steps was found to dominate total resistance, whereas grain roughness on step treads was a small component of total resistance. The relative contributions of grain, spill, and woody debris resistance were strongly influenced by discharge and to a lesser extent by LWD density. Grain resistance values based on published formulas and debris resistance values calculated using a cylinder drag approach typically underestimated analogous flume‐derived values, further illustrating sources of error in partitioning methods and the importance of accounting for interaction effects between resistance components.

Flow resistance dynamics in step-pool channels: 2. Partitioning between grain, spill, and woody debris resistance

NASA Astrophysics Data System (ADS)

Wilcox, Andrew C.; Nelson, Jonathan M.; Wohl, Ellen E.

2006-05-01

In step-pool stream channels, flow resistance is created primarily by bed sediments, spill over step-pool bed forms, and large woody debris (LWD). In order to measure resistance partitioning between grains, steps, and LWD in step-pool channels we completed laboratory flume runs in which total resistance was measured with and without grains and steps, with various LWD configurations, and at multiple slopes and discharges. Tests of additive approaches to resistance partitioning found that partitioning estimates are highly sensitive to the order in which components are calculated and that such approaches inflate the values of difficult-to-measure components that are calculated by subtraction from measured components. This effect is especially significant where interactions between roughness features create synergistic increases in resistance such that total resistance measured for combinations of resistance components greatly exceeds the sum of those components measured separately. LWD contributes large proportions of total resistance by creating form drag on individual pieces and by increasing the spill resistance effect of steps. The combined effect of LWD and spill over steps was found to dominate total resistance, whereas grain roughness on step treads was a small component of total resistance. The relative contributions of grain, spill, and woody debris resistance were strongly influenced by discharge and to a lesser extent by LWD density. Grain resistance values based on published formulas and debris resistance values calculated using a cylinder drag approach typically underestimated analogous flume-derived values, further illustrating sources of error in partitioning methods and the importance of accounting for interaction effects between resistance components.

Heat flow through a basaltic outcrop on a sedimented young ridge flank

NASA Astrophysics Data System (ADS)

Wheat, C. Geoffrey; Mottl, Michael J.; Fisher, Andrew T.; Kadko, David; Davis, Earl E.; Baker, Edward

2004-12-01

One hundred seven thermal gradients were measured in shallow surface sediments using the submersible Alvin within a 0.5 km2 area on and around the 65-m-high, mostly sediment-covered Baby Bare outcrop located on the eastern flank of the Juan de Fuca Ridge. Heat flow values range from 0.35 W m-2, which is close to the average value (0.27 W m-2) for the sediment-buried 3.5-Myr-old crust surrounding the outcrop, to as high as 490 W m-2. Some measurements are purely conductive, whereas others are consistent with upward fluid seepage through this sediment layer. Highest heat flow values are found roughly 10 m below the summit along a ridge-parallel fault where shimmering water, springs, and communities of clams were found. Heat flow values surrounding a second fault are elevated to a lesser extent (maximum of 9.2 W m-2). The total power output from this 0.5 km2 area is 1.5 MW, about 10 times greater than the conductive power output predicted for a commensurate area of 3.5-Myr crust. Much of this heat loss is conductive (˜84%), consistent with an independent estimate of the convective heat flux from Rn/heat anomalies in spring fluids and in the water column above the springs. Calculations suggest that the 64°C isotherm, which is the temperature in the surrounding upper crust, is <20 m below the summit, corresponding to a height that is 30 m above the surrounding turbidite plain. These elevated fluid temperatures at shallow depths provide thermal buoyance to drive seafloor seepage from the outcrop.

Comparison of ASL and DCE MRI for the non-invasive measurement of renal blood flow: quantification and reproducibility.

PubMed

Cutajar, Marica; Thomas, David L; Hales, Patrick W; Banks, T; Clark, Christopher A; Gordon, Isky

2014-06-01

To investigate the reproducibility of arterial spin labelling (ASL) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and quantitatively compare these techniques for the measurement of renal blood flow (RBF). Sixteen healthy volunteers were examined on two different occasions. ASL was performed using a multi-TI FAIR labelling scheme with a segmented 3D-GRASE imaging module. DCE MRI was performed using a 3D-FLASH pulse sequence. A Bland-Altman analysis was used to assess repeatability of each technique, and determine the degree of correspondence between the two methods. The overall mean cortical renal blood flow (RBF) of the ASL group was 263 ± 41 ml min(-1) [100 ml tissue](-1), and using DCE MRI was 287 ± 70 ml min(-1) [100 ml tissue](-1). The group coefficient of variation (CVg) was 18 % for ASL and 28 % for DCE-MRI. Repeatability studies showed that ASL was more reproducible than DCE with CVgs of 16 % and 25 % for ASL and DCE respectively. Bland-Altman analysis comparing the two techniques showed a good agreement. The repeated measures analysis shows that the ASL technique has better reproducibility than DCE-MRI. Difference analysis shows no significant difference between the RBF values of the two techniques. Reliable non-invasive monitoring of renal blood flow is currently clinically unavailable. Renal arterial spin labelling MRI is robust and repeatable. Renal dynamic contrast-enhanced MRI is robust and repeatable. ASL blood flow values are similar to those obtained using DCE-MRI.

Determination of compound-specific Hg isotope ratios from transient signals using gas chromatography coupled to multicollector inductively coupled plasma mass spectrometry (MC-ICP/MS).

PubMed

Dzurko, Mark; Foucher, Delphine; Hintelmann, Holger

2009-01-01

MeHg and inorganic Hg compounds were measured in aqueous media for isotope ratio analysis using aqueous phase derivatization, followed by purge-and-trap preconcentration. Compound-specific isotope ratio measurements were performed by gas chromatography interfaced to MC-ICP/MS. Several methods of calculating isotope ratios were evaluated for their precision and accuracy and compared with conventional continuous flow cold vapor measurements. An apparent fractionation of Hg isotopes was observed during the GC elution process for all isotope pairs, which necessitated integration of signals prior to the isotope ratio calculation. A newly developed average peak ratio method yielded the most accurate isotope ratio in relation to values obtained by a continuous flow technique and the best reproducibility. Compound-specific isotope ratios obtained after GC separation were statistically not different from ratios measured by continuous flow cold vapor measurements. Typical external uncertainties were 0.16 per thousand RSD (n = 8) for the (202)Hg(/198)Hg ratio of MeHg and 0.18 per thousand RSD for the same ratio in inorganic Hg using the optimized operating conditions. Using a newly developed reference standard addition method, the isotopic composition of inorganic Hg and MeHg synthesized from this inorganic Hg was measured in the same run, obtaining a value of delta (202)Hg = -1.49 +/- 0.47 (2SD; n = 10). For optimum performance a minimum mass of 2 ng per Hg species should be introduced onto the column.

Factors affecting the viscosity of sodium hypochlorite and their effect on irrigant flow.

PubMed

Bukiet, F; Soler, T; Guivarch, M; Camps, J; Tassery, H; Cuisinier, F; Candoni, N

2013-10-01

To assess the influence of concentration, temperature and surfactant addition to a sodium hypochlorite solution on its dynamic viscosity and to calculate the corresponding Reynolds number to determine the corresponding flow regimen. The dynamic viscosity of the irrigant was assessed using a rotational viscometer. Sodium hypochlorite with concentrations ranging from 0.6% to 9.6% was tested at 37 and 22 °C. A wide range of concentrations of three different surfactants was mixed in 2.4% sodium hypochlorite for viscosity measurements. The Reynolds number was calculated under each condition. Data were analysed using two-way anova. There was a significant influence of sodium hypochlorite concentration (P < 0.001) and temperature (P < 0.001) on dynamic viscosity: the latter significantly increased with sodium hypochlorite concentration and decreased with temperature. A significant influence of surfactant concentration on dynamic viscosity (P < 0.001) occurred, especially for high surfactant concentrations: 6.25% for benzalkonium chloride, 15% for Tween 80 and 6.25% for Triton X-100. Reynolds number values calculated for a given flow rate (0.14 mL s(-1)), and root canal diameter (sizes 45 and 70) clearly qualified the irrigant flow regimen as laminar. Dynamic viscosity increased with sodium hypochlorite and surfactant concentration but decreased with temperature. Under clinical conditions, all viscosities measured led to laminar flow. The transition between laminar and turbulent flow may be reached by modifying different parameters at the same time: increasing flow rate and temperature whilst decreasing irrigant viscosity by adding surfactants with a high value of critical micellar concentration. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Assessment of actual transpiration rate in olive tree field combining sap-flow, leaf area index and scintillometer measurements

NASA Astrophysics Data System (ADS)

Agnese, C.; Cammalleri, C.; Ciraolo, G.; Minacapilli, M.; Provenzano, G.; Rallo, G.; de Bruin, H. A. R.

2009-09-01

Models to estimate the actual evapotranspiration (ET) in sparse vegetation area can be fundamental for agricultural water managements, especially when water availability is a limiting factor. Models validation must be carried out by considering in situ measurements referred to the field scale, which is the relevant scale of the modelled variables. Moreover, a particular relevance assumes to consider separately the components of plant transpiration (T) and soil evaporation (E), because only the first is actually related to the crop stress conditions. Objective of the paper was to assess a procedure aimed to estimate olive trees actual transpiration by combining sap flow measurements with the scintillometer technique at field scale. The study area, located in Western Sicily (Italy), is mainly cultivated with olive crop and is characterized by typical Mediterranean semi-arid climate. Measurements of sap flow and crop actual evapotranspiration rate were carried out during 2008 irrigation season. Crop transpiration fluxes, measured on some plants by means of sap flow sensors, were upscaled considering the leaf area index (LAI). The comparison between evapotranspiration values, derived by displaced-beam small-aperture scintillometer (DBSAS-SLS20, Scintec AG), with the transpiration fluxes obtained by the sap flow sensors, also allowed to evaluate the contribute of soil evaporation in an area characterized by low vegetation coverage.

Noncontact diffuse optical assessment of blood flow changes in head and neck free tissue transfer flaps

NASA Astrophysics Data System (ADS)

Huang, Chong; Radabaugh, Jeffrey P.; Aouad, Rony K.; Lin, Yu; Gal, Thomas J.; Patel, Amit B.; Valentino, Joseph; Shang, Yu; Yu, Guoqiang

2015-07-01

Knowledge of tissue blood flow (BF) changes after free tissue transfer may enable surgeons to predict the failure of flap thrombosis at an early stage. This study used our recently developed noncontact diffuse correlation spectroscopy to monitor dynamic BF changes in free flaps without getting in contact with the targeted tissue. Eight free flaps were elevated in patients with head and neck cancer; one of the flaps failed. Multiple BF measurements probing the transferred tissue were performed during and post the surgical operation. Postoperative BF values were normalized to the intraoperative baselines (assigning "1") for the calculation of relative BF change (rBF). The rBF changes over the seven successful flaps were 1.89±0.15, 2.26±0.13, and 2.43±0.13 (mean±standard error), respectively, on postoperative days 2, 4, and 7. These postoperative values were significantly higher than the intraoperative baseline values (p<0.001), indicating a gradual recovery of flap vascularity after the tissue transfer. By contrast, rBF changes observed from the unsuccessful flaps were 1.14 and 1.34, respectively, on postoperative days 2 and 4, indicating less flow recovery. Measurement of BF recovery after flap anastomosis holds the potential to act early to salvage ischemic flaps.

Noncontact diffuse optical assessment of blood flow changes in head and neck free tissue transfer flaps

PubMed Central

Huang, Chong; Radabaugh, Jeffrey P.; Aouad, Rony K.; Lin, Yu; Gal, Thomas J.; Patel, Amit B.; Valentino, Joseph; Shang, Yu; Yu, Guoqiang

2015-01-01

Abstract. Knowledge of tissue blood flow (BF) changes after free tissue transfer may enable surgeons to predict the failure of flap thrombosis at an early stage. This study used our recently developed noncontact diffuse correlation spectroscopy to monitor dynamic BF changes in free flaps without getting in contact with the targeted tissue. Eight free flaps were elevated in patients with head and neck cancer; one of the flaps failed. Multiple BF measurements probing the transferred tissue were performed during and post the surgical operation. Postoperative BF values were normalized to the intraoperative baselines (assigning “1”) for the calculation of relative BF change (rBF). The rBF changes over the seven successful flaps were 1.89±0.15, 2.26±0.13, and 2.43±0.13 (mean±standard error), respectively, on postoperative days 2, 4, and 7. These postoperative values were significantly higher than the intraoperative baseline values (p<0.001), indicating a gradual recovery of flap vascularity after the tissue transfer. By contrast, rBF changes observed from the unsuccessful flaps were 1.14 and 1.34, respectively, on postoperative days 2 and 4, indicating less flow recovery. Measurement of BF recovery after flap anastomosis holds the potential to act early to salvage ischemic flaps. PMID:26187444

Assessment of internal mammary artery and saphenous vein graft patency and flow reserve using transthoracic Doppler echocardiography

NASA Technical Reports Server (NTRS)

Chirillo, F.; Bruni, A.; Balestra, G.; Cavallini, C.; Olivari, Z.; Thomas, J. D.; Stritoni, P.

2001-01-01

OBJECTIVE: To investigate transthoracic Doppler echocardiography in the identification of coronary artery bypass graft (CABG) flow for assessing graft patency. DESIGN: The initial study group comprised 45 consecutive patients with previous CABG undergoing elective cardiac catheterisation for recurrent ischaemia. The Doppler variables best correlated with angiographic graft patency were then tested prospectively in a further 84 patients (test group). SETTING: Three tertiary referral centres. INTERVENTIONS: Flow velocities in grafts were recorded at rest and during hyperaemia induced by dipyridamole (0.56 mg/kg/4 min), under the guidance of transthoracic colour Doppler flow mapping. Findings on transthoracic Doppler were compared with angiography. MAIN OUTCOME MEASURES: Feasibility of identifying open grafts by Doppler and diagnostic accuracy for Doppler detection of significant (>/= 70%) graft stenosis. RESULTS: In the test group the identification rate for mammary artery grafts was 100%, for saphenous vein grafts to left anterior descending coronary artery 91%, for vein grafts to right coronary artery 96%, and for vein grafts to circumflex artery 90%. Coronary flow reserve (the ratio between peak diastolic velocity under hyperaemia and at baseline) of < 1.9 (95% confidence interval 1.83 to 2.08) had 100% sensitivity, 98% specificity, 87.5% positive predictive value, and 100% negative predictive value for mammary artery graft stenosis. Coronary flow reserve of < 1.6 (95% CI 1.51 to 1.73) had 91% sensitivity, 87% specificity, 85.4% positive predictive value, and 92.3% negative predictive value for significant vein graft stenosis. CONCLUSIONS: Transthoracic Doppler can provide non-invasive assessment of CABG patency.

Estimating soil hydraulic properties from soil moisture time series by inversion of a dual-permeability model

NASA Astrophysics Data System (ADS)

Dalla Valle, Nicolas; Wutzler, Thomas; Meyer, Stefanie; Potthast, Karin; Michalzik, Beate

2017-04-01

Dual-permeability type models are widely used to simulate water fluxes and solute transport in structured soils. These models contain two spatially overlapping flow domains with different parameterizations or even entirely different conceptual descriptions of flow processes. They are usually able to capture preferential flow phenomena, but a large set of parameters is needed, which are very laborious to obtain or cannot be measured at all. Therefore, model inversions are often used to derive the necessary parameters. Although these require sufficient input data themselves, they can use measurements of state variables instead, which are often easier to obtain and can be monitored by automated measurement systems. In this work we show a method to estimate soil hydraulic parameters from high frequency soil moisture time series data gathered at two different measurement depths by inversion of a simple one dimensional dual-permeability model. The model uses an advection equation based on the kinematic wave theory to describe the flow in the fracture domain and a Richards equation for the flow in the matrix domain. The soil moisture time series data were measured in mesocosms during sprinkling experiments. The inversion consists of three consecutive steps: First, the parameters of the water retention function were assessed using vertical soil moisture profiles in hydraulic equilibrium. This was done using two different exponential retention functions and the Campbell function. Second, the soil sorptivity and diffusivity functions were estimated from Boltzmann-transformed soil moisture data, which allowed the calculation of the hydraulic conductivity function. Third, the parameters governing flow in the fracture domain were determined using the whole soil moisture time series. The resulting retention functions were within the range of values predicted by pedotransfer functions apart from very dry conditions, where all retention functions predicted lower matrix potentials. The diffusivity function predicted values of a similar range as shown in other studies. Overall, the model was able to emulate soil moisture time series for low measurement depths, but deviated increasingly at larger depths. This indicates that some of the model parameters are not constant throughout the profile. However, overall seepage fluxes were still predicted correctly. In the near future we will apply the inversion method to lower frequency soil moisture data from different sites to evaluate the model's ability to predict preferential flow seepage fluxes at the field scale.

Can MR Measurement of Renal Artery Flow and Renal Volume Predict the Outcome of Percutaneous Transluminal Renal Angioplasty?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Binkert, Christoph A.; Debatin, Jorg F.; Schneider, Ernst

2001-07-15

Purpose: Predicting therapeutic benefit from percutaneous transluminal renal angioplasty (PTRA) in patients with renal artery stenosis (RAS) remains difficult. This study investigates whether magnetic resonance (MR)-based renal artery flow measurements relative to renal parenchymal volume can predict clinical outcome following PTRA.Methods: The data on 23 patients (13 men, 10 women; age range 47-82 years, mean age 64 years) were analyzed. The indication for treatment was hypertension (n = 18) or renal insufficiency (n = 5). Thirty-four cases of RAS were identified: bilateral disease was manifest in 11 and unilateral disease in 12 patients. The MR imaging protocol included a breath-hold,more » cardiac-gated cine phase-contrast sequence for renal flow measurement and a fast multiplanar spoiled gradient-echo sequence for renal volume measurement. MR measurements were performed on the day prior to and the day following PTRA. Clinical success was defined as (a) a reduction in diastolic blood pressure > 15% or (b) a reduction in serum creatinine > 20%. Kidneys were categorized as normal volume or low volume. A renal flow index (RFI) was calculated by dividing the renal flow (ml/min) by the renal volume (cm{sup 3}).Results: Clinical success was observed in 11 patients. Twelve patients did not benefit from angioplasty. Normal kidney volume was seen in 10 of 11 responders and in 8 of 12 nonresponders, resulting in a sensitivity of 91%, specificity of 33%, a positive predictive value (PPV) of 56% and a negative predictive value (NPV) of 80%. A RFI below a threshold of 1.5 ml/min/cm{sup 3} predicted successful outcome with 100% sensitivity, 33% specificity, 58% PPV, and 100% NPV. The combination of normal renal volume and a RFI below 1.5 ml/min/cm{sup 3} identified PTRA responders with a sensitivity of 91%, a specificity of 67%, a PPV of 71%, and a NPV of 89%. PTRA resulted in a greater increase in renal flow in responders compared with nonresponders (p < 0.001).Conclusion: A combination of cine phase-contrast MR renal flow and parenchymal volume measurements enables identification of patients benefiting from PTRA with a high sensitivity and NPV, but only moderate specificity and PPV.« less

Fundamental investigation of ARC interruption in gas flows

NASA Astrophysics Data System (ADS)

Benenson, D. M.; Frind, G.; Kinsinger, R. E.; Nagamatsu, H. T.; Noeske, H. O.; Sheer, R. E., Jr.

1980-07-01

Thermal recovery in gas blast interrupters is discussed. The thermal recovery process was investigated with physical and aerodynamic methods, typically using reduced size nozzles and short sinusoidal current pulses. Aerodynamic characterization of the cold flow fields in several different nozzle types included measurements of the pressure and flow fields, both steady-state and turbulent components, with special attention given to wakes and shock structures. Special schlieren techniques on DC arcs and high speed photography on arcs in orifice nozzles show that shock heating broadens the arc independent of turbulence effects and produces a poorly recovering downstream arc section. Measured recovery speeds in both orifice and convergent-divergent nozzles agree with predictions of several arc theories assuming turbulent power losses. However, data on post-zero currents and power loss show values much smaller than theoretical predictions. Hydrogen, deuterium, and methane were measured.

Measuring the mechanical efficiency of a working cardiac muscle sample at body temperature using a flow-through calorimeter.

PubMed

Taberner, Andrew J; Johnston, Callum M; Pham, Toan; June-Chiew Han; Ruddy, Bryan P; Loiselle, Denis S; Nielsen, Poul M F

2015-08-01

We have developed a new `work-loop calorimeter' that is capable of measuring, simultaneously, the work-done and heat production of isolated cardiac muscle samples at body temperature. Through the innovative use of thermoelectric modules as temperature sensors, the development of a low-noise fluid-flow system, and implementation of precise temperature control, the heat resolution of this device is 10 nW, an improvement by a factor of ten over previous designs. These advances have allowed us to conduct the first flow-through measurements of work output and heat dissipation from cardiac tissue at body temperature. The mechanical efficiency is found to vary with peak stress, and reaches a peak value of approximately 15 %, a figure similar to that observed in cardiac muscle at lower temperatures.

( sup 99m Tc)diphosphonate uptake and hemodynamics in arthritis of the immature dog knee

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, E.S.; Soballe, K.; Henriksen, T.B.

1991-03-01

The relationship between (99mTc)diphosphonate uptake and bone hemodynamics was studied in canine carrageenan-induced juvenile chronic arthritis. Blood flow was determined with microspheres, plasma and red cell volumes were measured by labeled fibrinogen and red cells, and the microvascular volume and mean transit time of blood were calculated. Normal femoral epiphyses had lower central and higher subchondral blood flow and diphosphonate uptake values. Epiphyseal vascular volume was uniform, resulting in a greater transit time of blood centrally. In arthritis, blood flow and diphosphonate uptake were increased subchondrally and unaffected centrally, while epiphyseal vascular volume was increased throughout, leading to prolonged transitmore » time centrally. The normal metaphyses had low blood flow and diphosphonate uptake values in cancellous bone and very high values in growth plates, but a large vascular volume throughout. The mean transit time therefore was low in growth plates and high in adjacent cancellous bone. Arthritis caused decreased blood flow and diphosphonate uptake in growth plates but increased vascular volume and transit time of blood. Diphosphonate uptake correlated positively with blood flow and plasma volume and negatively with red cell volume in a nonlinear fashion. Thus, changes in diphosphonate uptake and microvascular hemodynamics occur in both epiphyseal and metaphyseal bone in chronic synovitis of the immature knee. The (99mTc)diphosphonate bone scan seems to reflect blood flow, plasma volume, and red cell volume of bone.« less

Empirical flow parameters - a tool for hydraulic model validity assessment : [summary].

DOT National Transportation Integrated Search

2013-10-01

Hydraulic modeling assembles models based on generalizations of parameter values from textbooks, professional literature, computer program documentation, and engineering experience. Actual measurements adjacent to the model location are seldom availa...

Numerical Simulation of Flow Field Within Parallel Plate Plastometer

NASA Technical Reports Server (NTRS)

Antar, Basil N.

2002-01-01

Parallel Plate Plastometer (PPP) is a device commonly used for measuring the viscosity of high polymers at low rates of shear in the range 10(exp 4) to 10(exp 9) poises. This device is being validated for use in measuring the viscosity of liquid glasses at high temperatures having similar ranges for the viscosity values. PPP instrument consists of two similar parallel plates, both in the range of 1 inch in diameter with the upper plate being movable while the lower one is kept stationary. Load is applied to the upper plate by means of a beam connected to shaft attached to the upper plate. The viscosity of the fluid is deduced from measuring the variation of the plate separation, h, as a function of time when a specified fixed load is applied on the beam. Operating plate speeds measured with the PPP is usually in the range of 10.3 cm/s or lower. The flow field within the PPP can be simulated using the equations of motion of fluid flow for this configuration. With flow speeds in the range quoted above the flow field between the two plates is certainly incompressible and laminar. Such flows can be easily simulated using numerical modeling with computational fluid dynamics (CFD) codes. We present below the mathematical model used to simulate this flow field and also the solutions obtained for the flow using a commercially available finite element CFD code.

An Evaluation of Selected Extraordinary Floods in the United States Reported by the U.S. Geological Survey and Implications for Future Advancement of Flood Science

USGS Publications Warehouse

Costa, John E.; Jarrett, Robert D.

2008-01-01

Thirty flood peak discharges determine the envelope curve of maximum floods documented in the United States by the U.S. Geological Survey. These floods occurred from 1927 to 1978 and are extraordinary not just in their magnitude, but in their hydraulic and geomorphic characteristics. The reliability of the computed discharge of these extraordinary floods was reviewed and evaluated using current (2007) best practices. Of the 30 flood peak discharges investigated, only 7 were measured at daily streamflow-gaging stations that existed when the flood occurred, and 23 were measured at miscellaneous (ungaged) sites. Methods used to measure these 30 extraordinary flood peak discharges consisted of 21 slope-area measurements, 2 direct current-meter measurements, 1 culvert measurement, 1 rating-curve extension, and 1 interpolation and rating-curve extension. The remaining four peak discharges were measured using combinations of culvert, slope-area, flow-over-road, and contracted-opening measurements. The method of peak discharge determination for one flood is unknown. Changes to peak discharge or rating are recommended for 20 of the 30 flood peak discharges that were evaluated. Nine floods retained published peak discharges, but their ratings were downgraded. For two floods, both peak discharge and rating were corrected and revised. Peak discharges for five floods that are subject to significant uncertainty due to complex field and hydraulic conditions, were re-rated as estimates. This study resulted in 5 of the 30 peak discharges having revised values greater than about 10 percent different from the original published values. Peak discharges were smaller for three floods (North Fork Hubbard Creek, Texas; El Rancho Arroyo, New Mexico; South Fork Wailua River, Hawaii), and two peak discharges were revised upward (Lahontan Reservoir tributary, Nevada; Bronco Creek, Arizona). Two peak discharges were indeterminate because they were concluded to have been debris flows with peak discharges that were estimated by an inappropriate method (slope-area) (Big Creek near Waynesville, North Carolina; Day Creek near Etiwanda, California). Original field notes and records could not be found for three of the floods, however, some data (copies of original materials, records of reviews) were available for two of these floods. A rating was assigned to each of seven peak discharges that had no rating. Errors identified in the reviews include misidentified flow processes, incorrect drainage areas for very small basins, incorrect latitude and longitude, improper field methods, arithmetic mistakes in hand calculations, omission of measured high flows when developing rating curves, and typographical errors. Common problems include use of two-section slope-area measurements, poor site selection, uncertainties in Manning's n-values, inadequate review, lost data files, and insufficient and inadequately described high-water marks. These floods also highlight the extreme difficulty in making indirect discharge measurements following extraordinary floods. Significantly, none of the indirect measurements are rated better than fair, which indicates the need to improve methodology to estimate peak discharge. Highly unsteady flow and resulting transient hydraulic phenomena, two-dimensional flow patterns, debris flows at streamflow-gaging stations, and the possibility of disconnected flow surfaces are examples of unresolved problems not well handled by current indirect discharge methodology. On the basis of a comprehensive review of 50,000 annual peak discharges and miscellaneous floods in California, problems with individual flood peak discharges would be expected to require a revision of discharge or rating curves at a rate no greater than about 0.10 percent of all floods. Many extraordinary floods create complex flow patterns and processes that cannot be adequately documented with quasi-steady, uniform one-dimensional analyses. These floods are most accura

Cerebral blood flow response to changes in arterial carbon dioxide tension during hypothermic cardiopulmonary bypass in children

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kern, F.H.; Ungerleider, R.M.; Quill, T.J.

1991-04-01

We examined the relationship of changes in partial pressure of carbon dioxide on cerebral blood flow responsiveness in 20 pediatric patients undergoing hypothermic cardiopulmonary bypass. Cerebral blood flow was measured during steady-state hypothermic cardiopulmonary bypass with the use of xenon 133 clearance methodology at two different arterial carbon dioxide tensions. During these measurements there was no significant change in mean arterial pressure, nasopharyngeal temperature, pump flow rate, or hematocrit value. Cerebral blood flow was found to be significantly greater at higher arterial carbon dioxide tensions (p less than 0.01), so that for every millimeter of mercury rise in arterial carbonmore » dioxide tension there was a 1.2 ml.100 gm-1.min-1 increase in cerebral blood flow. Two factors, deep hypothermia (18 degrees to 22 degrees C) and reduced age (less than 1 year), diminished the effect carbon dioxide had on cerebral blood flow responsiveness but did not eliminate it. We conclude that cerebral blood flow remains responsive to changes in arterial carbon dioxide tension during hypothermic cardiopulmonary bypass in infants and children; that is, increasing arterial carbon dioxide tension will independently increase cerebral blood flow.« less

Sustained High Basal Motion of the Greenland Ice Sheet Revealed by Borehole Deformation

NASA Technical Reports Server (NTRS)

Ryser, Claudia; Luthi, Martin P.; Andrews, Lauren C.; Hoffman, Matthew, J.; Catania, Ginny A.; Hawley, Robert L.; Neumann, Thomas A.; Kristensen, Steen S.

2014-01-01

Ice deformation and basal motion characterize the dynamical behavior of the Greenland ice sheet (GrIS). We evaluate the contribution of basal motion from ice deformation measurements in boreholes drilled to the bed at two sites in the western marginal zone of the GrIS. We find a sustained high amount of basal motion contribution to surface velocity of 44-73 percent in winter, and up to 90 percent in summer. Measured ice deformation rates show an unexpected variation with depth that can be explained with the help of an ice-flow model as a consequence of stress transfer from slippery to sticky areas. This effect necessitates the use of high-order ice-flow models, not only in regions of fast-flowing ice streams but in all temperate-based areas of the GrIS. The agreement between modeled and measured deformation rates confirms that the recommended values of the temperature-dependent flow rate factor A are a good choice for ice-sheet models.

Turbulent boundary layer in high Rayleigh number convection in air.

PubMed

du Puits, Ronald; Li, Ling; Resagk, Christian; Thess, André; Willert, Christian

2014-03-28

Flow visualizations and particle image velocimetry measurements in the boundary layer of a Rayleigh-Bénard experiment are presented for the Rayleigh number Ra=1.4×1010. Our visualizations indicate that the appearance of the flow structures is similar to ordinary (isothermal) turbulent boundary layers. Our particle image velocimetry measurements show that vorticity with both positive and negative sign is generated and that the smallest flow structures are 1 order of magnitude smaller than the boundary layer thickness. Additional local measurements using laser Doppler velocimetry yield turbulence intensities up to I=0.4 as in turbulent atmospheric boundary layers. From our observations, we conclude that the convective boundary layer becomes turbulent locally and temporarily although its Reynolds number Re≈200 is considerably smaller than the value 420 underlying existing phenomenological theories. We think that, in turbulent Rayleigh-Bénard convection, the transition of the boundary layer towards turbulence depends on subtle details of the flow field and is therefore not universal.

Simulation of blood flow through an artificial heart

NASA Technical Reports Server (NTRS)

Kiris, Cetin; Chang, I-Dee; Rogers, Stuart E.; Kwak, Dochan

1991-01-01

A numerical simulation of the incompressible viscous flow through a prosthetic tilting disk heart valve is presented in order to demonstrate the current capability to model unsteady flows with moving boundaries. Both steady state and unsteady flow calculations are done by solving the incompressible Navier-Stokes equations in 3-D generalized curvilinear coordinates. In order to handle the moving boundary problems, the chimera grid embedding scheme which decomposes a complex computational domain into several simple subdomains is used. An algebraic turbulence model for internal flows is incorporated to reach the physiological values of Reynolds number. Good agreement is obtained between the numerical results and experimental measurements. It is found that the tilting disk valve causes large regions of separated flow, and regions of high shear.

Radionuclide migration: laboratory experiments with isolated fractures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rundberg, R.S.; Thompson, J.L.; Maestas, S.

Laboratory experiments examining flow and element migration in rocks containing isolated fractures have been initiated at the Los Alamos National Laboratory. Techniques are being developed to establish simple fracture flow systems which are appropriate to models using analytical solutions to the matrix diffusion-flow equations, such as those of I. Neretnieks [I. Neretnieks, Diffusion in the Rock Matrix: An Important Factor in Radionuclide Retardation? J. Geophys. Res. 85, 4379 (1980).] These experiments are intended to be intermediate steps toward larger scale field experiments where it may become more difficult to establish and control the parameters important to nuclide migration in fracturedmore » media. Laboratory experiments have been run on fractures ranging in size from 1 to 20 cm in length. The hydraulic flow in these fractures was studied to provide the effective apertures. The flows established in these fracture systems are similar to those in the granite fracture flow experiments of Witherspoon et al. [P.A. Witherspoon, J.S.Y. Wang, K. Iwai, and J.E. Gale, Validity of Cubic Law for Fluid Flow in a Deformable Rock Fracture, Lawrence Berkeley Laboratory report LBL-9557 (October 1979).] Traced solutions containing {sup 85}Sr and {sup 137}Cs were flowed through fractures in Climax Stock granite and welded tuff (Bullfrog and Tram members, Yucca Mountain, Nevada Test Site). The results of the elutions through granite agree with the matrix diffusion calculations based on independent measurements of K/sub d/. The results of the elutions through tuff, however, agree only if the K/sub d/ values used in the calculations are lower than the K/sub d/ values measured using a batch technique. This trend has been previously observed in chromatographic column experiments with tuff. 5 figures, 3 tables.« less

Turbulent Boundary Layers in Oscillating Flows. Part 1: an Experimental and Computational Study

NASA Technical Reports Server (NTRS)

Cook, W. J.

1986-01-01

An experimental-computational study of the behavior of turbulent boundary layers for oscillating air flows over a plane surface with a small favorable mean pressure gradient is described. Experimental studies were conducted for boundary layers generated on the test section wall of a facility that produces a flow with a mean free stream velocity and a superposed nearly-pure sinusoidal component over a wide range of frequency. Flow at a nominal mean free stream velocity of 50 m/s were studied at atmospheric pressure and temperature at selected axial positions over a 2 m test length for frequencies ranging from 4 to 29 Hz. Quantitative experimental results are presented for unsteady velocity profiles and longitudinal turbulence levels obtained from hot wire anemometer measurements at three axial positions. Mean velocity profiles for oscillating flows were found to exhibit only small deviations from corresponding steady flow profiles, while amplitudes and phase relationships exhibited a strong dependence on axial position and frequency. Since sinusoidal flows could be generated over a wide range of frequency, studies at fixed values of reduced frequency at different axial positions were studied. Results show that there is some utility in the use of reduced frequency to correlate unsteady velocity results. The turbulence level u' sub rms was observed to vary essentially sinusoidally around values close to those measured in steady flow. However, the amplitude of oscillation and phase relations for turbulence level were found to be strongly frequency dependent. Numerical predictions were obtained using an unsteady boundary layer computational code and the Cebeci-Smith and Glushko turbulence models. Predicted quantities related to unsteady velocity profiles exhibit fair agreement with experiment when the Cebeci-Smith turbulence model is used.

Modelling Cerebral Blood Flow and Temperature Using a Vascular Porous Model

NASA Astrophysics Data System (ADS)

Blowers, Stephen; Thrippleton, Michael; Marshall, Ian; Harris, Bridget; Andrews, Peter; Valluri, Prashant

2016-11-01

Macro-modelling of cerebral blood flow can assist in determining the impact of temperature intervention to reduce permanent tissue damage during instances of brain trauma. Here we present a 3D two phase fluid-porous model for simulating blood flow through the capillary region linked to intersecting 1D arterial and venous vessel trees. This combined vasculature porous (VaPor) model simulates both flow and energy balances, including heat from metabolism, using a vasculature extracted from MRI data which are expanded upon using a tree generation algorithm. Validation of temperature balance has been achieved using rodent brain data. Direct flow validation is not as straight forward due to the method used in determining regional cerebral blood flow (rCBF). In-vivo measurements are achieved using a tracer, which disagree with direct measurements of simulated flow. However, by modelling a virtual tracer, rCBF values are obtained that agree with those found in literature. Temperature profiles generated with the VaPor model show a reduction in core brain temperature after cooling the scalp not seen previously in other models.

[Echocardiography in Boid snakes: Demonstration and blood flow measurements].

PubMed

Schroff, S; Starck, J M; Krautwald-Junghanns, M-E; Pees, M

2012-01-01

Comparative echocardiography and blood flow measurements in different boid species. 51 healthy snakes from seven different species were examined echocardiographically under standardized conditions. The heart and the great vessels were displayed using 2-D-ultrasonography. Pulsed-wave doppler technique measurements of the blood flow within the vessels were performed and results analyzed statistically. The examinations could be performed in non-sedated snakes in ventral recumbency. The best image quality was obtained using the ventrolateral coupling site. An examination scheme applicable to all examined snake species was established. Diversity in the anatomy of vessels could be detected in different snake species. A characteristic shape of the curve demonstrating the blood flow against time could be shown for the respective vessels. There were positive correlations between the size of the snakes and the absolute blood flow (total flow, systemic flow, pulmonary flow to body length: p<0.001; r=0.770; r=0.627; r=0.766; respectively to body mass: p<0.001; r=0.815; r=0.698; r=0.788), as well as negative correlations between the size of the animals and the blood flow relative to body mass (total flow, systemic flow, pulmonary flow to body length: p<0.001; r=-0.533; r=-0.512; r=-0.478; respectively total flow to body mass: p<0.001; r=-0.768). When using standardized conditions, echocardiography in boid snakes is a useful diagnostic tool for the assessment of cardiac function. Reference values provided in this study serve as a basis for ultrasound examination in veterinary practice.

Uncertainly Analysis of Two Types of Humidity Sensors by a Humidity Generator with a Divided-Flow System.

PubMed

Chen, Ling-Hsi; Chen, Chiachung

2018-02-21

Humidity measurement is an important technique for the agricultural, foods, pharmaceuticals, and chemical industries. For the sake of convenience, electrical relative humidity (RH) sensors have been widely used. These sensors need to be calibrated to ensure their accuracy and the uncertainty measurement of these sensors has become a major concern. In this study, a self-made divided-flow generator was established to calibrate two types of electrical humidity sensors. The standard reference humidity was calculated from dew-point temperature and air dry-bulb temperature measured by a chilled mirror monitor. This divided-flow generator could produce consistent result of RH measurement results. The uncertainty of the reference standard increased with the increase of RH values. The combined uncertainty with the adequate calibration equations were ranged from 0.82% to 1.45% RH for resistive humidity sensors and 0.63% to 1.4% for capacitive humidity sensors, respectively. This self-made, divided-flow generator, and calibration method are cheap, time-saving, and easy to be used. Thus, the proposed approach can easily be applied in research laboratories.

Uncertainly Analysis of Two Types of Humidity Sensors by a Humidity Generator with a Divided-Flow System

PubMed Central

Chen, Ling-Hsi

2018-01-01

Humidity measurement is an important technique for the agricultural, foods, pharmaceuticals, and chemical industries. For the sake of convenience, electrical relative humidity (RH) sensors have been widely used. These sensors need to be calibrated to ensure their accuracy and the uncertainty measurement of these sensors has become a major concern. In this study, a self-made divided-flow generator was established to calibrate two types of electrical humidity sensors. The standard reference humidity was calculated from dew-point temperature and air dry-bulb temperature measured by a chilled mirror monitor. This divided-flow generator could produce consistent result of RH measurement results. The uncertainty of the reference standard increased with the increase of RH values. The combined uncertainty with the adequate calibration equations were ranged from 0.82% to 1.45% RH for resistive humidity sensors and 0.63% to 1.4% for capacitive humidity sensors, respectively. This self-made, divided-flow generator, and calibration method are cheap, time-saving, and easy to be used. Thus, the proposed approach can easily be applied in research laboratories. PMID:29466313

Application of a Line Laser Scanner for Bed Form Tracking in a Laboratory Flume

NASA Astrophysics Data System (ADS)

de Ruijsscher, T. V.; Hoitink, A. J. F.; Dinnissen, S.; Vermeulen, B.; Hazenberg, P.

2018-03-01

A new measurement method for continuous detection of bed forms in movable bed laboratory experiments is presented and tested. The device consists of a line laser coupled to a 3-D camera, which makes use of triangulation. This allows to measure bed forms during morphodynamic experiments, without removing the water from the flume. A correction is applied for the effect of laser refraction at the air-water interface. We conclude that the absolute measurement error increases with increasing flow velocity, its standard deviation increases with water depth and flow velocity, and the percentage of missing values increases with water depth. Although 71% of the data is lost in a pilot moving bed experiment with sand, still high agreement between flowing water and dry bed measurements is found when a robust LOcally weighted regrESSion (LOESS) procedure is applied. This is promising for bed form tracking applications in laboratory experiments, especially when lightweight sediments like polystyrene are used, which require smaller flow velocities to achieve dynamic similarity to the prototype. This is confirmed in a moving bed experiment with polystyrene.

Regional Cerebral Blood Flow In Dementia: Receiver-Operating-Characteristic Analysis

NASA Astrophysics Data System (ADS)

Zemcov, Alexander; Barclay, Laurie; Sansone, Joseph; Blass, John P.; Metz, Charles E.

1985-06-01

The coupling of mentation to regional cerebral blood flow (rCBF) has prompted the application of the Xe-133 inhalation method of measuring rCBF in the differential diagnosis of the two most common dementing diseases, Alzheimer's disease and multi-infarct dementia (MID). In this study receiver-operating-characteristic (ROC) curve analysis was used to assess the effectiveness of a 32 detector Xe-133 inhalation system in discriminating between patients with Alzheimer's disease and normal controls, MID patients and normal controls and between patients with Alzheimer's disease and MID. The populations were clinically evaluated as 1) normal (age 63.1 + 13.1, n=23), 2) Alzheimer's disease (age 72.7 + 7.0, n=82), 3) MID (age 76.4 + 7.6, n=27): The mean flow values for all detectors were lowest for the Alzheimer's disease group, larger for the MID group and largest for the normal controls. The dynamic relationship between the correct identifications (true posi-tives) versus incorrect identifications (false positives) per detector for any 2 pairs of clinical groups varies as the cutoff value of flow is changed over the range of experimental blood flow values. Therefore a quantitative characterization of the "decision" or ROC curve (TP vs FP) for each detector and for each pair of clinical groups provides a measure of the overall diagnostic efficacy of the detector. Detectors directed approximately toward the speech, auditory and association cortices were most effective in disciminatinq between each of the dementia groups and the controls. Frontal detectors were diagnostically inefficient. The Xe-133 inhalation system provided virtually no diagnostic power in discriminating between the two forms of dementia, however. Therefore this imaging technology is most useful when assessing the general diagnostic state of dementia (Alz-heimer's disease and MID) from normal cognitive function.

Normal reference values for regional pulmonary peripheral airspace epithelial permeability. Influence of pneumonectomy and the smoking habit.

PubMed

Todisco, T; Dottorini, M; Rossi, F; Baldoncini, A; Palumbo, R

1989-01-01

Peripheral airspace epithelial permeability (PAEP) to diethylentriaminopentacetate (DTPA), an index of pulmonary integrity, was measured in 3 groups of subjects for different purposes: (1) to establish vertical regional reference values; (2) to determine the physiological role of acute doubling of total pulmonary blood flow; (3) to quantify the pulmonary epithelial damage in smokers and the possibility of lung protection by an agent stimulating surfactant production. This study broadens previous knowledge of PAEP. First of all, regional reference values are given for young normal nonsmoking subjects and the existence of a vertical gradient of PAEP is confirmed. Furthermore, this study shows that this gradient is independent of the vertical blood flow gradient, since an acute increase of total blood flow in pneumonectomized patients does not modify the regional distribution of PAEP. Finally, it is confirmed that the cigarette smoker's lung is more permeable than the controls and that probably a drug-stimulating surfactant production gives some protection against damage due to chronic smoking.

Estimating drain flow from measured water table depth in layered soils under free and controlled drainage

NASA Astrophysics Data System (ADS)

Saadat, Samaneh; Bowling, Laura; Frankenberger, Jane; Kladivko, Eileen

2018-01-01

Long records of continuous drain flow are important for quantifying annual and seasonal changes in the subsurface drainage flow from drained agricultural land. Missing data due to equipment malfunction and other challenges have limited conclusions that can be made about annual flow and thus nutrient loads from field studies, including assessments of the effect of controlled drainage. Water table depth data may be available during gaps in flow data, providing a basis for filling missing drain flow data; therefore, the overall goal of this study was to examine the potential to estimate drain flow using water table observations. The objectives were to evaluate how the shape of the relationship between drain flow and water table height above drain varies depending on the soil hydraulic conductivity profile, to quantify how well the Hooghoudt equation represented the water table-drain flow relationship in five years of measured data at the Davis Purdue Agricultural Center (DPAC), and to determine the impact of controlled drainage on drain flow using the filled dataset. The shape of the drain flow-water table height relationship was found to depend on the selected hydraulic conductivity profile. Estimated drain flow using the Hooghoudt equation with measured water table height for both free draining and controlled periods compared well to observed flow with Nash-Sutcliffe Efficiency values above 0.7 and 0.8 for calibration and validation periods, respectively. Using this method, together with linear regression for the remaining gaps, a long-term drain flow record for a controlled drainage experiment at the DPAC was used to evaluate the impacts of controlled drainage on drain flow. In the controlled drainage sites, annual flow was 14-49% lower than free drainage.

Methods to Evaluate Influence of Onsite Septic Wastewater-Treatment Systems on Base Flow in Selected Watersheds in Gwinnett County, Georgia, October 2007

USGS Publications Warehouse

Landers, Mark N.; Ankcorn, Paul D.

2008-01-01

The influence of onsite septic wastewater-treatment systems (OWTS) on base-flow quantity needs to be understood to evaluate consumptive use of surface-water resources by OWTS. If the influence of OWTS on stream base flow can be measured and if the inflow to OWTS is known from water-use data, then water-budget approaches can be used to evaluate consumptive use. This report presents a method to evaluate the influence of OWTS on ground-water recharge and base-flow quantity. Base flow was measured in Gwinnett County, Georgia, during an extreme drought in October 2007 in 12 watersheds that have low densities of OWTS (22 to 96 per square mile) and 12 watersheds that have high densities (229 to 965 per square mile) of OWTS. Mean base-flow yield in the high-density OWTS watersheds is 90 percent greater than in the low-density OWTS watersheds. The density of OWTS is statistically significant (p-value less than 0.01) in relation to base-flow yield as well as specific conductance. Specific conductance of base flow increases with OWTS density, which may indicate influence from treated wastewater. The study results indicate considerable unexplained variation in measured base-flow yield for reasons that may include: unmeasured processes, a limited dataset, and measurement errors. Ground-water recharge from a high density of OWTS is assumed to be steady state from year to year so that the annual amount of increase in base flow from OWTS is expected to be constant. In dry years, however, OWTS contributions represent a larger percentage of natural base flow than in wet years. The approach of this study could be combined with water-use data and analyses to estimate consumptive use of OWTS.

Cutaneous heat flow during heating and cooling in Alligator mississipiensis.

PubMed

Smith, E N

1976-05-01

Direct in vivo measurement of heat flow across the skin of the American alligator (Alligator mississipiensis) showed increased heat flow during warming. Mean values at 25 degrees C during warming (15-35 degrees C) in air (airspeed 300 cm/s) were 17.9 +/- 92 SE cal/cm2 per h (mean alligator wt 3.27 kg). Cooling heat flow at the same temperature was 13.6 +/- 0.57 cal/cm2 per h. Subdermal heat flow was reduced during warming and was not significantly different from cutaneous heat flow during cooling. This indicated that the alligator was able to control its rate of heat exchange with the environment by altering cutaneous perfusion. Atropine, phenoxybenzamine, nitroglycerin, and Xylocaine did not affect cutaneous heat flow or heating and cooling rates. Atropine blocked bradycardia during cooling.

3-D High-Lift Flow-Physics Experiment - Transition Measurements

NASA Technical Reports Server (NTRS)

McGinley, Catherine B.; Jenkins, Luther N.; Watson, Ralph D.; Bertelrud, Arild

2005-01-01

An analysis of the flow state on a trapezoidal wing model from the NASA 3-D High Lift Flow Physics Experiment is presented. The objective of the experiment was to characterize the flow over a non-proprietary semi-span three-element high-lift configuration to aid in assessing the state of the art in the computation of three-dimensional high-lift flows. Surface pressures and hot-film sensors are used to determine the flow conditions on the slat, main, and flap. The locations of the attachments lines and the values of the attachment line Reynolds number are estimated based on the model surface pressures. Data from the hot-films are used to determine if the flow is laminar, transitional, or turbulent by examining the hot-film time histories, statistics, and frequency spectra.

Contribution of piezometric measurement to knowledge and management of low water levels: examples on the chalk aquifer in the Champagne Ardennes region

NASA Astrophysics Data System (ADS)

Stollsteiner, P.; Bessiere, H.; Nicolas, J.; Allier, D.; Berthet, O.

2015-04-01

This article is based on a BRGM study on piezometric indicators, threshold values of discharge and groundwater levels for the assessment of potentially-exploitable water resources of chalky watersheds. A method for estimating low water levels based on groundwater levels is presented from three examples representing chalk aquifers with different cycles: annual, combined and interannual. The first is located in Picardy and the two others in the Champagne-Ardennes region. Piezometers with annual cycles, used in these examples, are supposed to be representative of the aquifer hydro-dynamics. Except for multi-annual systems, the analysis between discharge measurements at a hydrometric station and groundwater levels measured at a piezometer representative of the main aquifer, leads to relatively precise and satisfactory relationships within a chalky context. These relationships may be useful for monitoring, validation, extension or reconstruction of the low water flow data. On the one hand, they allow definition of the piezometric levels corresponding to the different alert thresholds of river discharges. On the other hand, they clarify the proportions of low surface water flow from runoff or drainage of the aquifer. Finally, these correlations give an assessment of the minimum flow for the coming weeks. However, these correlations cannot be used to optimize the value of the exploitable water resource because it seems to be difficult to integrate the value of the effective rainfall that could occur during the draining period. Moreover, in the case of multi-annual systems, the solution is to attempt a comprehensive system modelling and, if it is satisfactory, using the simulated values to get rid of parasites or running the model for forecasting purposes.

Evaluating Uncertainties in Coronal Electron Temperature and Radial Speed Measurements Using a Simulation of the Bastille Day Eruption

NASA Astrophysics Data System (ADS)

Reginald, Nelson; St. Cyr, Orville; Davila, Joseph; Rastaetter, Lutz; Török, Tibor

2018-05-01

Obtaining reliable measurements of plasma parameters in the Sun's corona remains an important challenge for solar physics. We previously presented a method for producing maps of electron temperature and speed of the solar corona using K-corona brightness measurements made through four color filters in visible light, which were tested for their accuracies using models of a structured, yet steady corona. In this article we test the same technique using a coronal model of the Bastille Day (14 July 2000) coronal mass ejection, which also contains quiet areas and streamers. We use the coronal electron density, temperature, and flow speed contained in the model to determine two K-coronal brightness ratios at (410.3, 390.0 nm) and (423.3, 398.7 nm) along more than 4000 lines of sight. Now assuming that for real observations, the only information we have for each line of sight are these two K-coronal brightness ratios, we use a spherically symmetric model of the corona that contains no structures to interpret these two ratios for electron temperature and speed. We then compare the interpreted (or measured) values for each line of sight with the true values from the model at the plane of the sky for that same line of sight to determine the magnitude of the errors. We show that the measured values closely match the true values in quiet areas. However, in locations of coronal structures, the measured values are predictably underestimated or overestimated compared to the true values, but can nevertheless be used to determine the positions of the structures with respect to the plane of the sky, in front or behind. Based on our results, we propose that future white-light coronagraphs be equipped to image the corona using four color filters in order to routinely create coronal maps of electron density, temperature, and flow speed.

The NASA Langley laminar-flow-control experiment on a swept, supercritical airfoil: Suction coefficient analysis

NASA Technical Reports Server (NTRS)

Brooks, Cuyler W., Jr.; Harris, Charles D.; Harvey, William D.

1991-01-01

A swept supercritical wing incorporating laminar flow control at transonic flow conditions was designed and tested. The definition of an experimental suction coefficient and a derivation of the compressible and incompressible formulas for the computation of the coefficient from measurable quantities is presented. The suction flow coefficient in the highest velocity nozzles is shown to be overpredicted by as much as 12 percent through the use of an incompressible formula. However, the overprediction on the computed value of suction drag when some of the suction nozzles were operating in the compressible flow regime is evaluated and found to be at most 6 percent at design conditions.

Experimental scaling law for the subcritical transition to turbulence in plane Poiseuille flow.

PubMed

Lemoult, Grégoire; Aider, Jean-Luc; Wesfreid, José Eduardo

2012-02-01

We present an experimental study of the transition to turbulence in a plane Poiseuille flow. Using a well-controlled perturbation, we analyze the flow by using extensive particle image velocimetry and flow visualization (using laser-induced fluorescence) measurements, and use the deformation of the mean velocity profile as a criterion to characterize the state of the flow. From a large parametric study, four different states are defined, depending on the values of the Reynolds number and the amplitude of the perturbation. We discuss the role of coherent structures, such as hairpin vortices, in the transition. We find that the minimal amplitude of the perturbation triggering transition scales asymptotically as Re(-1).

Analysis of low flows and selected methods for estimating low-flow characteristics at partial-record and ungaged stream sites in western Washington

USGS Publications Warehouse

Curran, Christopher A.; Eng, Ken; Konrad, Christopher P.

2012-01-01

Regional low-flow regression models for estimating Q7,10 at ungaged stream sites are developed from the records of daily discharge at 65 continuous gaging stations (including 22 discontinued gaging stations) for the purpose of evaluating explanatory variables. By incorporating the base-flow recession time constant τ as an explanatory variable in the regression model, the root-mean square error for estimating Q7,10 at ungaged sites can be lowered to 72 percent (for known values of τ), which is 42 percent less than if only basin area and mean annual precipitation are used as explanatory variables. If partial-record sites are included in the regression data set, τ must be estimated from pairs of discharge measurements made during continuous periods of declining low flows. Eight measurement pairs are optimal for estimating τ at partial-record sites, and result in a lowering of the root-mean square error by 25 percent. A low-flow survey strategy that includes paired measurements at partial-record sites requires additional effort and planning beyond a standard strategy, but could be used to enhance regional estimates of τ and potentially reduce the error of regional regression models for estimating low-flow characteristics at ungaged sites.

An inter-laboratory comparison of PNH clone detection by high-sensitivity flow cytometry in a Russian cohort.

PubMed

Sipol, Alexandra A; Babenko, Elena V; Borisov, Vyacheslav I; Naumova, Elena V; Boyakova, Elena V; Yakunin, Dimitry I; Glazanova, Tatyana V; Chubukina, Zhanna V; Pronkina, Natalya V; Popov, Alexander M; Saveliev, Leonid I; Lugovskaya, Svetlana A; Lisukov, Igor A; Kulagin, Alexander D; Illingworth, Andrea J

2015-01-01

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal stem cell disorder characterized by partial or absolute deficiency of glycophosphatidyl-inositol (GPI) anchor-linked surface proteins on blood cells. A lack of precise diagnostic standards for flow cytometry has hampered useful comparisons of data between laboratories. We report data from the first study evaluating the reproducibility of high-sensitivity flow cytometry for PNH in Russia. PNH clone sizes were determined at diagnosis in PNH patients at a central laboratory and compared with follow-up measurements in six laboratories across the country. Analyses in each laboratory were performed according to recommendations from the International Clinical Cytometry Society (ICCS) and the more recent 'practical guidelines'. Follow-up measurements were compared with each other and with the values determined at diagnosis. PNH clone size measurements were determined in seven diagnosed PNH patients (five females, two males: mean age 37 years); five had a history of aplastic anemia and three (one with and two without aplastic anemia) had severe hemolytic PNH and elevated plasma lactate dehydrogenase. PNH clone sizes at diagnosis were low in patients with less severe clinical symptoms (0.41-9.7% of granulocytes) and high in patients with severe symptoms (58-99%). There were only minimal differences in the follow-up clone size measurement for each patient between the six laboratories, particularly in those with high values at diagnosis. The ICCS-recommended high-sensitivity flow cytometry protocol was effective for detecting major and minor PNH clones in Russian PNH patients, and showed high reproducibility between laboratories.

Construction and calibration of a groundwater-flow model to assess groundwater availability in the uppermost principal aquifer systems of the Williston Basin, United States and Canada

USGS Publications Warehouse

Davis, Kyle W.; Long, Andrew J.

2018-05-31

The U.S. Geological Survey developed a groundwater-flow model for the uppermost principal aquifer systems in the Williston Basin in parts of Montana, North Dakota, and South Dakota in the United States and parts of Manitoba and Saskatchewan in Canada as part of a detailed assessment of the groundwater availability in the area. The assessment was done because of the potential for increased demands and stresses on groundwater associated with large-scale energy development in the area. As part of this assessment, a three-dimensional groundwater-flow model was developed as a tool that can be used to simulate how the groundwater-flow system responds to changes in hydrologic stresses at a regional scale.The three-dimensional groundwater-flow model was developed using the U.S. Geological Survey’s numerical finite-difference groundwater model with the Newton-Rhapson solver, MODFLOW–NWT, to represent the glacial, lower Tertiary, and Upper Cretaceous aquifer systems for steady-state (mean) hydrological conditions for 1981‒2005 and for transient (temporally varying) conditions using a combination of a steady-state period for pre-1960 and transient periods for 1961‒2005. The numerical model framework was constructed based on existing and interpreted hydrogeologic and geospatial data and consisted of eight layers. Two layers were used to represent the glacial aquifer system in the model; layer 1 represented the upper one-half and layer 2 represented the lower one-half of the glacial aquifer system. Three layers were used to represent the lower Tertiary aquifer system in the model; layer 3 represented the upper Fort Union aquifer, layer 4 represented the middle Fort Union hydrogeologic unit, and layer 5 represented the lower Fort Union aquifer. Three layers were used to represent the Upper Cretaceous aquifer system in the model; layer 6 represented the upper Hell Creek hydrogeologic unit, layer 7 represented the lower Hell Creek aquifer, and layer 8 represented the Fox Hills aquifer. The numerical model was constructed using a uniform grid with square cells that are about 1 mile (1,600 meters) on each side with a total of about 657,000 active cells.Model calibration was completed by linking Parameter ESTimation (PEST) software with MODFLOW–NWT. The PEST software uses statistical parameter estimation techniques to identify an optimum set of input parameters by adjusting individual model input parameters and assessing the differences, or residuals, between observed (measured or estimated) data and simulated values. Steady-state model calibration consisted of attempting to match mean simulated values to measured or estimated values of (1) hydraulic head, (2) hydraulic head differences between model layers, (3) stream infiltration, and (4) discharge to streams. Calibration of the transient model consisted of attempting to match simulated and measured temporally distributed values of hydraulic head changes, stream base flow, and groundwater discharge to artesian flowing wells. Hydraulic properties estimated through model calibration included hydraulic conductivity, vertical hydraulic conductivity, aquifer storage, and riverbed hydraulic conductivity in addition to groundwater recharge and well skin.The ability of the numerical model to accurately simulate groundwater flow in the Williston Basin was assessed primarily by its ability to match calibration targets for hydraulic head, stream base flow, and flowing well discharge. The steady-state model also was used to assess the simulated potentiometric surfaces in the upper Fort Union aquifer, the lower Fort Union aquifer, and the Fox Hills aquifer. Additionally, a previously estimated regional groundwater-flow budget was compared with the simulated steady-state groundwater-flow budget for the Williston Basin. The simulated potentiometric surfaces typically compared well with the estimated potentiometric surfaces based on measured hydraulic head data and indicated localized groundwater-flow gradients that were topographically controlled in outcrop areas and more generalized regional gradients where the aquifers were confined. The differences between the measured and simulated (residuals) hydraulic head values for 11,109 wells were assessed, which indicated that the steady-state model generally underestimated hydraulic head in the model area. This underestimation is indicated by a positive mean residual of 11.2 feet for all model layers. Layer 7, which represents the lower Hell Creek aquifer, is the only layer for which the steady-state model overestimated hydraulic head. Simulated groundwater-level changes for the transient model matched within plus or minus 2.5 feet of the measured values for more than 60 percent of all measurements and to within plus or minus 17.5 feet for 95 percent of all measurements; however, the transient model underestimated groundwater-level changes for all model layers. A comparison between simulated and estimated base flows for the steady-state and transient models indicated that both models overestimated base flow in streams and underestimated annual fluctuations in base flow.The estimated and simulated groundwater budgets indicate the model area received a substantial amount of recharge from precipitation and stream infiltration. The steady-state model indicated that reservoir seepage was a larger component of recharge in the Williston Basin than was previously estimated. Irrigation recharge and groundwater inflow from outside the Williston Basin accounted for a relatively small part of total groundwater recharge when compared with recharge from precipitation, stream infiltration, and reservoir seepage. Most of the estimated and simulated groundwater discharge in the Williston Basin was to streams and reservoirs. Simulated groundwater withdrawal, discharge to reservoirs, and groundwater outflow in the Williston Basin accounted for a smaller part of total groundwater discharge.The transient model was used to simulate discharge to 571 flowing artesian wells within the model area. Of the 571 established flowing artesian wells simulated by the model, 271 wells did not flow at any time during the simulation because hydraulic head was always below the land-surface altitude. As hydraulic head declined throughout the simulation, 68 of these wells responded by ceasing to flow by the end of 2005. Total mean simulated discharge for the 571 flowing artesian wells was 55.1 cubic feet per second (ft3/s), and the mean simulated flowing well discharge for individual wells was 0.118 ft3/s. Simulated discharge to individual flowing artesian wells increased from 0.039 to 0.177 ft3/s between 1961 and 1975 and decreased to 0.102 ft3/s by 2005. The mean residual for 34 flowing wells with measured discharge was 0.014 ft3/s, which indicates the transient model overestimated discharge to flowing artesian wells in the model area.Model limitations arise from aspects of the conceptual model and from simplifications inherent in the construction and calibration of a regional-scale numerical groundwater-flow model. Simplifying assumptions in defining hydraulic parameters in space and hydrologic stresses and time-varying observational data in time can limit the capabilities of this tool to simulate how the groundwater-flow system responds to changes in hydrologic stresses, particularly at the local scale; nevertheless, the steady-state model adequately simulated flow in the uppermost principal aquifer systems in the Williston Basin based on the comparison between the simulated and estimated groundwater-flow budget, the comparison between simulated and estimated potentiometric surfaces, and the results of the calibration process.

Measuring the Osmotic Water Permeability of the Plant Protoplast Plasma Membrane: Implication of the Nonosmotic Volume

PubMed Central

2010-01-01

Starting from the original theoretical descriptions of osmotically induced water volume flow in membrane systems, a convenient procedure to determine the osmotic water permeability coefficient (Pos) and the relative nonosmotic volume (β) of individual protoplasts is presented. Measurements performed on protoplasts prepared from pollen grains and pollen tubes of Lilium longiflorum cv. Thunb. and from mesophyll cells of Nicotiana tabacum L. and Arabidopsis thaliana revealed low values for the osmotic water permeability coefficient in the range 5–20 μm · s−1 with significant differences in Pos, depending on whether β is considered or not. The value of β was determined using two different methods: by interpolation from Boyle-van’t Hoff plots or by fitting a solution of the theoretical equation for water volume flow to the whole volume transients measured during osmotic swelling. The values determined with the second method were less affected by the heterogeneity of the protoplast samples and were around 30% of the respective isoosmotic protoplast volume. It is therefore important to consider nonosmotic volume in the calculation of Pos as plant protoplasts behave as nonideal osmometers. PMID:17568979

Effects of linking a soil-water-balance model with a groundwater-flow model

USGS Publications Warehouse

Stanton, Jennifer S.; Ryter, Derek W.; Peterson, Steven M.

2013-01-01

A previously published regional groundwater-flow model in north-central Nebraska was sequentially linked with the recently developed soil-water-balance (SWB) model to analyze effects to groundwater-flow model parameters and calibration results. The linked models provided a more detailed spatial and temporal distribution of simulated recharge based on hydrologic processes, improvement of simulated groundwater-level changes and base flows at specific sites in agricultural areas, and a physically based assessment of the relative magnitude of recharge for grassland, nonirrigated cropland, and irrigated cropland areas. Root-mean-squared (RMS) differences between the simulated and estimated or measured target values for the previously published model and linked models were relatively similar and did not improve for all types of calibration targets. However, without any adjustment to the SWB-generated recharge, the RMS difference between simulated and estimated base-flow target values for the groundwater-flow model was slightly smaller than for the previously published model, possibly indicating that the volume of recharge simulated by the SWB code was closer to actual hydrogeologic conditions than the previously published model provided. Groundwater-level and base-flow hydrographs showed that temporal patterns of simulated groundwater levels and base flows were more accurate for the linked models than for the previously published model at several sites, particularly in agricultural areas.

Flow determination of a pump-turbine at zero discharge

NASA Astrophysics Data System (ADS)

Edinger, G.; Erne, S.; Doujak, E.; Bauer, C.

2014-03-01

When starting up a reversible Francis pump-turbine in pump mode, the machine may operate at zero flow at a given gate opening. Besides reversal flow and prerotation in the draft tube cone, the onset of a fully separated flow in the vaned diffuser is observable at zero- discharge condition. In this paper, the occurrence of prerotation and reversal flow in the conical draft tube and the flow in one stay vane channel of a pump-turbine are examined experimentally and compared to numerical simulations. In order to assess the strongly three-dimensional flow in the stay vane channel, measurements with a 2D laser doppler velocimeter (LDV) were performed at various positions. The inlet flow in the draft tube cone, which becomes significantly at zero discharge in pump mode, is investigated by velocity measurements at two different positions. Pressure fluctuations in the draft tube cone induced by complex flow patterns are also recorded and analyzed. It is found that the swirl number at zero discharge does not significant differ from the values obtained at very low load pumping. Experimental investigations combined with CFD have shown that in the stay vane channel flow velocity components different from zero occur even at no discharge. Streamline plots show the fully separated flow structure.

Fast perfusion measurements in rat skeletal muscle at rest and during exercise with single-voxel FAIR (flow-sensitive alternating inversion recovery).

PubMed

Pohmann, Rolf; Künnecke, Basil; Fingerle, Jürgen; von Kienlin, Markus

2006-01-01

Non-invasive measurement of perfusion in skeletal muscle by in vivo magnetic resonance remains a challenge due to its low level and the correspondingly low signal-to-noise ratio. To enable accurate, quantitative, and time-resolved perfusion measurements in the leg muscle, a technique with a high sensitivity is required. By combining a flow-sensitive alternating inversion recovery (FAIR)-sequence with a single-voxel readout, we have developed a new technique to measure the perfusion in the rat gastrocnemius muscle at rest, yielding an average value of 19.4 +/- 4.8 mL/100 g/min (n = 22). In additional experiments, perfusion changes were elicited by acute ischemia and reperfusion or by exercise induced by electrical, noninvasive muscle stimulation with varying duration and intensity. The perfusion time courses during these manipulations were measured with a temporal resolution of 2.2 min, showing increases in perfusion of a factor of up to 2.5. In a direct comparison, the results agreed closely with values found with microsphere measurements in the same animals. The quantitative and noninvasive method can significantly facilitate the investigation of atherosclerotic diseases and the examination of drug efficacy.

Electron-Ion Recombination Rate Coefficient Measurements in a Flowing Afterglow Plasma

NASA Technical Reports Server (NTRS)

Gougousi, Theodosia; Golde, Michael F.; Johnsen, Rainer

1996-01-01

The flowing-afterglow technique in conjunction with computer modeling of the flowing plasma has been used to determine accurate dissociative-recombination rate coefficients alpha for the ions O2(+), HCO(+), CH5(+), C2H5(+), H3O(+), CO2(+), HCO2(+), HN2O(+), and N2O(+) at 295 K. We find that the simple form of data analysis that was employed in earlier experiments was adequate and we largely confirm earlier results. In the case of HCO(+) ions, published coefficients range from 1.1 X 10(exp -7) to 2.8 x 10(exp -7) cu cm/S, while our measurements give a value of 1.9 x 10(exp -7) cu cm/S.

Lunar heat flow experiments: Science objectives and a strategy for minimizing the effects of lander-induced perturbations

NASA Astrophysics Data System (ADS)

Kiefer, Walter S.

2012-01-01

Reliable measurements of the Moon's global heat flow would serve as an important diagnostic test for models of lunar thermal evolution and would also help to constrain the Moon's bulk abundance of radioactive elements and its differentiation history. The two existing measurements of lunar heat flow are unlikely to be representative of the global heat flow. For these reasons, obtaining additional heat flow measurements has been recognized as a high priority lunar science objective. In making such measurements, it is essential that the design and deployment of the heat flow probe and of the parent spacecraft do not inadvertently modify the near-surface thermal structure of the lunar regolith and thus perturb the measured heat flow. One type of spacecraft-related perturbation is the shadow cast by the spacecraft and by thermal blankets on some instruments. The thermal effects of these shadows propagate by conduction both downward and outward from the spacecraft into the lunar regolith. Shadows cast by the spacecraft superstructure move over the surface with time and only perturb the regolith temperature in the upper 0.8 m. Permanent shadows, such as from thermal blankets covering a seismometer or other instruments, can modify the temperature to greater depth. Finite element simulations using measured values of the thermal diffusivity of lunar regolith show that the limiting factor for temperature perturbations is the need to measure the annual thermal wave for 2 or more years to measure the thermal diffusivity. The error induced by permanent spacecraft thermal shadows can be kept below 8% of the annual wave amplitude at 1 m depth if the heat flow probe is deployed at least 2.5 m away from any permanent spacecraft shadow. Deploying the heat flow probe 2 m from permanent shadows permits measuring the annual thermal wave for only one year and should be considered the science floor for a heat flow experiment on the Moon. One way to meet this separation requirement would be to deploy the heat flow and seismology experiments on opposite sides of the spacecraft. This result should be incorporated in the design of future lunar geophysics spacecraft experiments. Differences in the thermal environments of the Moon and Mars result in less restrictive separation requirements for heat flow experiments on Mars.

Laser Doppler flowmetry for measurement of laminar capillary blood flow in the horse

NASA Astrophysics Data System (ADS)

Adair, Henry S., III

1998-07-01

Current methods for in vivo evaluation of digital hemodynamics in the horse include angiography, scintigraphy, Doppler ultrasound, electromagnetic flow and isolated extracorporeal pump perfused digit preparations. These techniques are either non-quantifiable, do not allow for continuous measurement, require destruction of the horse orare invasive, inducing non- physiologic variables. In vitro techniques have also been reported for the evaluation of the effects of vasoactive agents on the digital vessels. The in vitro techniques are non-physiologic and have evaluated the vasculature proximal to the coronary band. Lastly, many of these techniques require general anesthesia or euthanasia of the animal. Laser Doppler flowmetry is a non-invasive, continuous measure of capillary blood flow. Laser Doppler flowmetry has been used to measure capillary blood flow in many tissues. The principle of this method is to measure the Doppler shift, that is, the frequency change that light undergoes when reflected by moving objects, such as red blood cells. Laser Doppler flowmetry records a continuous measurement of the red cell motion in the outer layer of the tissue under study, with little or no influence on physiologic blood flow. This output value constitutes the flux of red cells and is reported as capillary perfusion units. No direct information concerning oxygen, nutrient or waste metabolite exchange in the surrounding tissue is obtained. The relationship between the flowmeter output signal and the flux of red blood cells is linear. The principles of laser Doppler flowmetry will be discussed and the technique for laminar capillary blood flow measurements will be presented.

4D flow MRI assessment of extracranial-intracranial bypass: qualitative and quantitative evaluation of the hemodynamics.

PubMed

Sekine, Tetsuro; Takagi, Ryo; Amano, Yasuo; Murai, Yasuo; Orita, Erika; Matsumura, Yoshio; Kumita, Shin-Ichiro

2016-03-01

Our aim was to assess the feasibility of using time-resolved 3D phase-contrast (4D flow) MRI to characterize extracranial-intracranial (EC-IC) bypass. We enrolled 32 patients who underwent EC-IC bypass (15 men, 17 women; mean age 66.4 years). In all, 16 underwent radial artery graft (RAG) bypass and 16 underwent superficial temporal artery (STA) bypass. 4D flow MRI, time-of-flight (TOF) magnetic resonance angiography (MRA), and computed tomography angiography (CTA) were performed. Bypass patency, flow direction, and blood flow volume (BFV) of each artery were determined by 4D flow MRI. Arterial diameters were measured by TOF-MRA and CTA. We compared RAG and STA bypasses by evaluating the flow direction and BFV of each artery. We evaluated the correlation between arterial diameters (measured by CTA or MRA) and the BFV and the detectability of flow direction (measured by 4D flow MRI) of each artery. 4D flow MRI confirmed the patency of each bypass artery. Flow direction of the M1 segment of the middle cerebral artery and BFV in the bypass artery differed between RAG and STA groups (p < 0.01). BFV in the bypass slightly correlated with the diameters on CTA (p < 0.05, R (2) = 0.287). Of the 29 arteries in the circle of Willis, nine were not depicted on 4D flow MRI. Cutoff values for arterial diameters on CTA and TOF-MRA for detecting the artery on 4D flow MRI were 2.4 and 1.8 mm, respectively. 4D flow MRI provided unique information for characterizing EC-IC bypasses, although this detectability is limited when addressing small arteries with slow flow.

Efficacy of the ejector flow-meter. A scavenging device for anaesthetic gases.

PubMed

Obel, D; Jørgensen, S; Ferguson, A; Frandsen, K

1985-01-01

Measurements of air concentrations of nitrous oxide and halothane in the breathing zone of the anaesthetist and the operating-room nurse were carried out during inhalation anaesthesia with a Mapleson D system. Gas removal was performed from inside the breathing system at the same rate as that of the fresh gas inflow by means of an ejector flow-meter. The concentrations of nitrous oxide and halothane were maintained below the Danish Threshold Limit Values of 100 and 5 parts per million, respectively, by using this type of scavenging. When these anaesthetics were used simultaneously, the reduced Threshold Limit Values were not exceeded during endotracheal anaesthesia.

Transition Within a Hypervelocity Boundary Layer on a 5-Degree Half-Angle Cone in Air/CO2 Mixtures

DTIC Science & Technology

2013-01-01

showed an increase in the reference Reynolds number Re* (see Equation 6 on page 8) at the point of transition as reservoir enthalpy hres in- creased...Germain and Adam also observed that flows of CO2 transitioned at higher values of Re* than flows of air for the same hres and Pres. Johnson et al. 5...symbol indicates that the flow was laminar to the last measurable ther- mocouple location, which is recorded. Experiment wCO2 hres Pres T ∗ xtr Retr

A heat-flow reconnaissance of southeastern Alaska.

USGS Publications Warehouse

Sass, J.H.; Lawver, L.A.; Munroe, R.J.

1985-01-01

Heat flow was measured at nine sites in crystalline and sedimentary rocks of SE Alaska. Seven of the sites, located between 115 and 155 km landward of the Queen Charlotte-Fairweather transform fault, have heat flows significantly higher than the mean in the coastal provinces between Cape Mendocino and the Queen Charlotte Islands, and lower than the mean for 81 values within 100 km of the San Andreas transform fault, even further S. There is no evidence for heat sources that might be associated with late Cainozoic thermal events.-P.Br.

40 CFR 60.704 - Test methods and procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... and hydrogen. (iii) Method 4 to measure the content of water vapor. (3) The volumetric flow rate shall... part) if published values are not available or cannot be calculated. Bws=Water vapor content of the...

40 CFR 60.704 - Test methods and procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... and hydrogen. (iii) Method 4 to measure the content of water vapor. (3) The volumetric flow rate shall... part) if published values are not available or cannot be calculated. Bws=Water vapor content of the...

FlowCal: A user-friendly, open source software tool for automatically converting flow cytometry data from arbitrary to calibrated units

PubMed Central

Castillo-Hair, Sebastian M.; Sexton, John T.; Landry, Brian P.; Olson, Evan J.; Igoshin, Oleg A.; Tabor, Jeffrey J.

2017-01-01

Flow cytometry is widely used to measure gene expression and other molecular biological processes with single cell resolution via fluorescent probes. Flow cytometers output data in arbitrary units (a.u.) that vary with the probe, instrument, and settings. Arbitrary units can be converted to the calibrated unit molecules of equivalent fluorophore (MEF) using commercially available calibration particles. However, there is no convenient, non-proprietary tool available to perform this calibration. Consequently, most researchers report data in a.u., limiting interpretation. Here, we report a software tool named FlowCal to overcome current limitations. FlowCal can be run using an intuitive Microsoft Excel interface, or customizable Python scripts. The software accepts Flow Cytometry Standard (FCS) files as inputs and is compatible with different calibration particles, fluorescent probes, and cell types. Additionally, FlowCal automatically gates data, calculates common statistics, and produces publication quality plots. We validate FlowCal by calibrating a.u. measurements of E. coli expressing superfolder GFP (sfGFP) collected at 10 different detector sensitivity (gain) settings to a single MEF value. Additionally, we reduce day-to-day variability in replicate E. coli sfGFP expression measurements due to instrument drift by 33%, and calibrate S. cerevisiae mVenus expression data to MEF units. Finally, we demonstrate a simple method for using FlowCal to calibrate fluorescence units across different cytometers. FlowCal should ease the quantitative analysis of flow cytometry data within and across laboratories and facilitate the adoption of standard fluorescence units in synthetic biology and beyond. PMID:27110723

Microcirculatory responses of sacral tissue in healthy individuals and inpatients on different pressure-redistribution mattresses.

PubMed

Bergstrand, S; Källman, U; Ek, A-C; Engström, M; Lindgren, M

2015-08-01

The aim of this study was to explore the interaction between interface pressure, pressure-induced vasodilation, and reactive hyperaemia with different pressure-redistribution mattresses. A cross-sectional study was performed with a convenience sample of healthy young individuals, and healthy older individuals and inpatients, at a university hospital in Sweden. Blood flow was measured at depths of 1mm, 2mm, and 10mm using laser Doppler flowmetry and photoplethysmography. The blood flow, interface pressure and skin temperature were measured in the sacral tissue before, during, and after load while lying on one standard hospital mattress and three different pressure-redistribution mattresses. There were significant differences between the average sacral pressure, peak sacral pressure, and local probe pressure on the three pressure-redistribution mattresses, the lowest values found were with the visco-elastic foam/air mattress (23.5 ± 2.5mmHg, 49.3 ± 11.1mmHg, 29.2 ± 14.0mmHg, respectively). Blood flow, measured as pressure-induced vasodilation, was most affected in the visco-elastic foam/air group compared to the alternating pressure mattress group at tissue depths of 2mm (39.0% and 20.0%, respectively), and 10mm (56.9 % and 35.1%, respectively). Subjects in all three groups, including healthy 18-65 year olds, were identified with no pressure-induced vasodilation or reactive hyperaemia on any mattress (n=11), which is considered a high-risk blood flow response. Interface pressure magnitudes considered not harmful during pressure-exposure on different pressure-redistribution mattresses can affect the microcirculation in different tissue structures. Despite having the lowest pressure values compared with the other mattresses, the visco-elastic foam/air mattress had the highest proportion of subjects with decreased blood flow. Healthy young individuals were identified with the high-risk blood flow response, suggesting an innate vulnerability to pressure exposure. Furthermore, the evaluation of pressure-redistribution support surfaces in terms of mean blood flow during and after tissue exposure is not feasible, but assessment of pressure-induced vasodilation and reactive hyperaemia could be a new way to assess individualised physiological measurements of mechanisms known to be related to pressure ulcer development.

Measurement of viscosity of gaseous mixtures at atmospheric pressure

NASA Technical Reports Server (NTRS)

Singh, J. J.; Mall, G. H.; Chegini, H.

1986-01-01

Coefficients of viscosity of various types of gas mixtures, including simulated natural-gas samples, have been measured at atmospheric pressure and room temperature using a modified capillary tube method. Pressure drops across the straight capillary tube section of a thermal mass flowmeter were measured for small, well-defined, volume flow rates for the test gases and for standard air. In this configuration, the flowmeter provides the volumetric flow rates as well as a well-characterized capillary section for differential pressure measurements across it. The coefficients of viscosity of the test gases were calculated using the reported value of 185.6 micro P for the viscosity of air. The coefficients of viscosity for the test mixtures were also calculated using Wilke's approximation of the Chapman-Enskog (C-E) theory. The experimental and calculated values for binary mixtures are in agreement within the reported accuracy of Wilke's approximation of the C-E theory. However, the agreement for multicomponent mixtures is less satisfactory, possible because of the limitations of Wilkes's approximation of the classical dilute-gas state model.

Flow tilt angle measurements using lidar anemometry

NASA Astrophysics Data System (ADS)

Dellwik, Ebba; Mann, Jakob

2010-05-01

A new way of estimating near-surface mean flow tilt angles from ground based Doppler lidar measurements is presented. The results are compared with traditional mast based in-situ sonic anemometry. The tilt angle assessed with the lidar is based on 10 or 30 minute mean values of the velocity field from a conically scanning lidar. In this mode of measurement, the lidar beam is rotated in a circle by a prism with a fixed angle to the vertical at varying focus distances. By fitting a trigonometric function to the scans, the mean vertical velocity can be estimated. Lidar measurements from (1) a fetch-limited beech forest site taken at 48-175m above ground level, (2) a reference site in flat agricultural terrain and (3) a second reference site in very complex terrain are presented. The method to derive flow tilt angles and mean vertical velocities from lidar has several advantages compared to sonic anemometry; there is no flow distortion caused by the instrument itself, there are no temperature effects and the instrument misalignment can be corrected for by comparing tilt estimates at various heights. Contrary to mast-based instruments, the lidar measures the wind field with the exact same alignment error at a multitude of heights. Disadvantages with estimating vertical velocities from a lidar compared to mast-based measurements are slightly increased levels of statistical errors due to limited sampling time, because the sampling is disjunct and a requirement for homogeneous flow. The estimated mean vertical velocity is biased if the flow over the scanned circle is not homogeneous. However, the error on the mean vertical velocity due to flow inhomogeneity can be approximated by a function of the angle of the lidar beam to the vertical, the measurement height and the vertical gradient of the mean vertical velocity, whereas the error due to flow inhomogeneity on the horizontal mean wind speed is independent of the lidar beam angle. For the presented measurements over forest, it is evaluated that the systematic error due to the inhomogeneity of the flow is less than 0.2 degrees. Other possibilities for utilizing lidars for flow tilt angle and mean vertical velocities are discussed.

Effects of Land-Use Changes and Ground-Water Withdrawals on Stream Base Flow, Pocono Creek Watershed, Monroe County, Pennsylvania

USGS Publications Warehouse

Sloto, Ronald A.

2008-01-01

The Pocono Creek watershed drains 46.5 square miles in eastern Monroe County, Pa. Between 2000 and 2020, the population of Monroe County is expected to increase by 70 percent, which will result in substantial changes in land-use patterns. An evaluation of the effect of reduced recharge from land-use changes and additional ground-water withdrawals on stream base flow was done by the U.S. Geological Survey (USGS) in cooperation with the U.S. Environmental Protection Agency (USEPA) and the Delaware River Basin Commission as part of the USEPA?s Framework for Sustainable Watershed Management Initiative. Two models were used. A Soil and Water Assessment Tool (SWAT) model developed by the USEPA provided areal recharge values for 2000 land use and projected full buildout land use. The USGS MODFLOW-2000 ground-water-flow model was used to estimate the effect of reduced recharge from changes in land use and additional ground-water withdrawals on stream base flow. This report describes the ground-water-flow-model simulations. The Pocono Creek watershed is underlain by sedimentary rock of Devonian age, which is overlain by a veneer of glacial deposits. All water-supply wells are cased into and derive water from the bedrock. In the ground-water-flow model, the surficial geologic units were grouped into six categories: (1) moraine deposits, (2) stratified drift, (3) lake deposits, (4) outwash, (5) swamp deposits, and (6) undifferentiated deposits. The unconsolidated surficial deposits are not used as a source of water. The ground-water and surface-water systems are well connected in the Pocono Creek watershed. Base flow measured on October 13, 2004, at 27 sites for model calibration showed that streams gained water between all sites measured except in the lower reach of Pocono Creek. The ground-water-flow model included the entire Pocono Creek watershed. Horizontally, the modeled area was divided into a 53 by 155 cell grid with 6,060 active cells. Vertically, the modeled area was discretized into four layers. Layers 1 and 2 represented the unconsolidated surficial deposits where they are present and bedrock where the surficial deposits are absent. Layer 3 represented shallow bedrock and was 200 ft (feet) thick. Layer 4 represented deep bedrock and was 300 ft thick. A total of 873 cells representing streams were assigned to layer 1. Recharge rates for model calibration were provided by the USEPA SWAT model for 2000 land-use conditions. Recharge rates for 2000 for the 29 subwatersheds in the SWAT model ranged from 6.11 to 22.66 inches per year. Because the ground-water-flow model was calibrated to base-flow data collected on October 13, 2004, the 2000 recharge rates were multiplied by 1.18 so the volume of recharge was equal to the volume of streamflow measured at the mouth of Pocono Creek. During model calibration, adjustments were made to aquifer hydraulic conductivity and streambed conductance. Simulated base flows and hydraulic heads were compared to measured base flows and hydraulic heads using the root mean squared error (RMSE) between measured and simulated values. The RMSE of the calibrated model for base flow was 4.7 cubic feet per second for 27 locations, and the RMSE for hydraulic heads for 15 locations was 35 ft. The USEPA SWAT model was used to provide areal recharge values for 2000 and full buildout land-use conditions. The change in recharge ranged from an increase of 37.8 percent to a decrease of 60.8 percent. The ground-water-flow model was used to simulate base flow for 2000 and full buildout land-use conditions using steady-state simulations. The decrease in simulated base flow ranged from 3.8 to 63 percent at the streamflow-measurement sites. Simulated base flow at streamflow-gaging station Pocono Creek above Wigwam Run near Stroudsburg, Pa. (01441495), decreased 25 percent. This is in general agreement with the SWAT model, which estimated a 30.6-percent loss in base flow at the streamflow-gaging station.

Magnetic resonance imaging-derived arterial peak flow in peripheral arterial disease: towards a standardized measurement.

PubMed

Versluis, B; Nelemans, P J; Wildberger, J E; Schurink, G-W; Leiner, T; Backes, W H

2014-08-01

To determine the best location to measure the arterial peak flow (APF) in patients with peripheral arterial disease in order to facilitate clinical standardization. Two hundred and fifty-nine patients with varying degrees of peripheral artery disease (PAD) and 48 patients without PAD were included. All patients underwent magnetic resonance phase-contrast imaging of the common femoral artery (CFA), superficial femoral artery (SFA), and popliteal artery (PA). APF values of patients with PAD were compared with patients with no PAD. The discriminative ability to identify PAD was evaluated by means of receiver-operator characteristic curves and the corresponding areas under the curve (AUC). Mean APF values in patients with PAD were reduced by 42%, 55% and 59% compared with non-PAD patients for the CFA, SFA, and PA, respectively (p < .01). The AUC's were 0.84, 0.92, and 0.93 for the CFA, SFA, and PA, respectively. The APF measured at the level of the PA shows the largest differences between patients with PAD and patients with no PAD and the best discriminative ability compared with the APF acquired in the CFA or SFA. The PA seems to be the most suitable level for standardized flow measurements in patients with PAD in order to obtain relevant functional information about the vascular status. Copyright © 2014 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Pilot Study of Laser Doppler Measurement of Flow Variability in the Microcirculation of the Palatal Mucosa

PubMed Central

Le Bars, Pierre; Niagha, Gaston; Kouadio, Ayepa Alain; Demoersman, Julien; Roy, Elisabeth; Armengol, Valérie; Soueidan, Assem

2016-01-01

Background. Histopathological alterations can arise when the denture-supporting mucosa experiences microbial and mechanical stress through the denture base and diagnosis of these diseases usually follows microvascular changes. Microcirculation measurement could allow for detection of such dysfunction and aid in the early diagnosis of palatal mucosa pathologies. Materials and Methods. We tested the sensitivity of laser Doppler for measuring the microcirculation of the palatal mucosa, assessing the median raphe (MR), Schroeder area (SA), and retroincisive papilla (RP). A Doppler PeriFlux 5000 System, containing a laser diode, was used. 54 healthy participants were recruited. We compare the measurements of PU (perfusion unit) using ANOVA test. Results. The numerical values for palatal mucosa blood flow differed significantly among the anatomical areas (p = 0.0167). The mean value of Schroeder area was 92.6 (SD: 38.4) and was significantly higher than the retroincisive papilla (51.9) (SD: 20.2) (p < 0.05), which in turn was higher than that of median raphe (31.9) (SD: 24.2) (p < 0.0001). Conclusion. Schroeder area appeared to have the greatest sensitivity, and vascular flow variability among individuals was also greatest in this region. We suggest that analysis of blood stream modification with laser Doppler of the palatal mucosa can help to detect onset signs of pathological alterations. PMID:27340663

Molecular Rayleigh Scattering Diagnostic for Measurement of High Frequency Temperature Fluctuations

NASA Technical Reports Server (NTRS)

Mielke, Amy F.; Elam, Kristie A.

2005-01-01

A novel technique for measurement of high frequency temperature fluctuations in unseeded gas flows using molecular Rayleigh scattering is investigated. The spectrum of laser light scattered from molecules in a gas flow is resolved using a Fabry-Perot interferometer. The width of the spectral peak is broadened by thermal motion of the molecules and hence is related to gas temperature. The interference fringe pattern containing spectral information is divided into four concentric regions using a series of mirrors angled with respect to one another. Light from each of these regions is directed towards photomultiplier tubes and sampled at 10 kHz using photon counting electronics. Monitoring the relative change in intensity within each region allows measurement of gas temperature. Independently monitoring the total scattered intensity provides a measure of gas density. This technique also has the potential to simultaneously measure a single component of flow velocity by monitoring the spectral peak location. Measurements of gas temperature and density are demonstrated using a low speed heated air jet surrounded by an unheated air co-flow. Mean values of temperature and density are shown for radial scans across the jet flow at a fixed axial distance from the jet exit plane. Power spectra of temperature and density fluctuations at several locations in the jet are also shown. The instantaneous measurements have fairly high uncertainty; however, long data records provide highly accurate statistically quantities, which include power spectra. Mean temperatures are compared with thermocouple measurements as well as the temperatures derived from independent density measurements. The accuracy for mean temperature measurements was +/- 7 K.

Control method for turbocharged diesel engines having exhaust gas recirculation

DOEpatents

Kolmanovsky, Ilya V.; Jankovic, Mrdjan J; Jankovic, Miroslava

2000-03-14

A method of controlling the airflow into a compression ignition engine having an EGR and a VGT. The control strategy includes the steps of generating desired EGR and VGT turbine mass flow rates as a function of the desired and measured compressor mass airflow values and exhaust manifold pressure values. The desired compressor mass airflow and exhaust manifold pressure values are generated as a function of the operator-requested fueling rate and engine speed. The EGR and VGT turbine mass flow rates are then inverted to corresponding EGR and VGT actuator positions to achieve the desired compressor mass airflow rate and exhaust manifold pressure. The control strategy also includes a method of estimating the intake manifold pressure used in generating the EGR valve and VGT turbine positions.

Cerebral blood flow in normal and abnormal sleep and dreaming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, J.S.; Ishikawa, Y.; Hata, T.

Measurements of regional or local cerebral blood flow (CBF) by the xenon-133 inhalation method and stable xenon computerized tomography CBF (CTCBF) method were made during relaxed wakefulness and different stages of REM and non-REM sleep in normal age-matched volunteers, narcoleptics, and sleep apneics. In the awake state, CBF values were reduced in both narcoleptics and sleep apneics in the brainstem and cerebellar regions. During sleep onset, whether REM or stage I-II, CBF values were paradoxically increased in narcoleptics but decreased severely in sleep apneics, while in normal volunteers they became diffusely but more moderately decreased. In REM sleep and dreamingmore » CBF values greatly increased, particularly in right temporo-parietal regions in subjects experiencing both visual and auditory dreaming.« less

Flow in a centrifugal fan impeller at off-design conditions

NASA Astrophysics Data System (ADS)

Wright, T.; Tzou, K. T. S.; Madhavan, S.

1984-06-01

A fully three-dimensional finite element analysis of inviscid, incompressible blade channel flow is the basis of the present study of both predicted and measured surface velocity and pressure distributions in the internal flow channels of a centrifugal fan impeller, for volume flow rates of 80-125 percent the design flow rate. The experimental results made extensive use of blade and sidewall surface pressure taps installed in a scale model of an airfoil-bladed centrifugal fan impeller. The results obtained illustrate the ability of both flow analyses to predict the dominant features of the impeller flow field, including peak blade surface velocities and adverse gradients at flows far from the design point. Insight is also gained into the limiting channel diffusion values for typical centrifugal cascade performance, together with the influence of viscous effects, as seen in deviations from ideal flow predictions.

Biomedical Effects of Chemical-Threat-Agent Antidote and Pretreatment Drugs. An Abstracted Bibliography. Volume 1.

DTIC Science & Technology

1986-04-01

Adams, R., Venna, P., Jackson, A., and Miller, R. TITLE: Plasma pharmacokinetics of intravenously administered atropine in normal human subjects Journal...atropine by i.v. route and inhalation. Measurements of respiratory airway resistance, N2 closing volume, maximal expiratory flow volume, pressure volume...maximum flow -static recoil and esophageal elasticity were compared to non-atropinized values. FINDINGS: "I.V. administration produced a marked

Specific Impulse and Mass Flow Rate Error

NASA Technical Reports Server (NTRS)

Gregory, Don A.

2005-01-01

Specific impulse is defined in words in many ways. Very early in any text on rocket propulsion a phrase similar to .specific impulse is the thrust force per unit propellant weight flow per second. will be found.(2) It is only after seeing the mathematics written down does the definition mean something physically to scientists and engineers responsible for either measuring it or using someone.s value for it.

Development of a diffraction imaging flow cytometer

PubMed Central

Jacobs, Kenneth M.; Lu, Jun Q.

2013-01-01

Diffraction images record angle-resolved distribution of scattered light from a particle excited by coherent light and can correlate highly with the 3D morphology of a particle. We present a jet-in-fluid design of flow chamber for acquisition of clear diffraction images in a laminar flow. Diffraction images of polystyrene spheres of different diameters were acquired and found to correlate highly with the calculated ones based on the Mie theory. Fast Fourier transform analysis indicated that the measured images can be used to extract sphere diameter values. These results demonstrate the significant potentials of high-throughput diffraction imaging flow cytometry for extracting 3D morphological features of cells. PMID:19794790

[The value of the thermocouple in the measurement of the gastric mucosal blood-flow. The influence of the occlusion of the celiac artery and prostaglandin E1 on the gastric mucosal blood flow. An experimental study in animals (author's transl)].

PubMed

Koch, H; Demling, L

1976-02-27

The study has been carried out to ensure the positive evidence of the measurement of the gastric mucosal blood-flow with the aid of the thermocouple (heat-clearance technique). The experiments have shown that the suction pressure of 600 mm mercury column which was used to fix the Thermocouple to the mucosa was indispensable in order to assess the blood-flow in the entire depth of the mucosa. Changes in the mucosal blood-flow are measuured at the same rate in all quadrants of the gastric corpus. The measuring of the blood-flow of a well circumscribed area of the mucosa is therefore representative for the entire corpus. Vasopressin led to a significant reduction of the gastric mucosal blood-flow measured with heat-clearance as well aminopyrine-clearance. There was a linear correlation between the results of both methods. Vasopressin selectively reduces the blood-flow of the gastric mucosa but not of the submucosa, the muscular layer and the serosa. Therefore it seems to be probable that changes in mucosal blood-flow selectively can be measured with the aid of the thermocouple. After previous stimulation with pentagastrin neither mucosal blood-flow nor acid secretion of the stomach were influenced by the occlusion of the celiac artery by 25 %. The occlusion of the celiac artery by 50 % reduced significantly the pentagastrin-stimulated gastric mucosal blood-flow whereas the acid secretion was not influenced. Prostaglandin E1 at a dose rate of 2 mug/kg-h increased significantly arterial and mucosal blood-flow as well as acid secretion of the stomach. In comparison PGE1 administered at a dose rate of 4 mug/kg-h reduced significantly gastric mucosal blood-flow and gastric secretion. PGE1 at a dose rate of 8 mug/kg-h did not produce any significant changes in blood-flow and secretion. The results suggested that the changes of gastric secretion observed with PGE1 were the consequence of primary changes in the gastric mucosal blood-flow.

FAIR exempting separate T (1) measurement (FAIREST): a novel technique for online quantitative perfusion imaging and multi-contrast fMRI.

PubMed

Lai, S; Wang, J; Jahng, G H

2001-01-01

A new pulse sequence, dubbed FAIR exempting separate T(1) measurement (FAIREST) in which a slice-selective saturation recovery acquisition is added in addition to the standard FAIR (flow-sensitive alternating inversion recovery) scheme, was developed for quantitative perfusion imaging and multi-contrast fMRI. The technique allows for clean separation between and thus simultaneous assessment of BOLD and perfusion effects, whereas quantitative cerebral blood flow (CBF) and tissue T(1) values are monitored online. Online CBF maps were obtained using the FAIREST technique and the measured CBF values were consistent with the off-line CBF maps obtained from using the FAIR technique in combination with a separate sequence for T(1) measurement. Finger tapping activation studies were carried out to demonstrate the applicability of the FAIREST technique in a typical fMRI setting for multi-contrast fMRI. The relative CBF and BOLD changes induced by finger-tapping were 75.1 +/- 18.3 and 1.8 +/- 0.4%, respectively, and the relative oxygen consumption rate change was 2.5 +/- 7.7%. The results from correlation of the T(1) maps with the activation images on a pixel-by-pixel basis show that the mean T(1) value of the CBF activation pixels is close to the T(1) of gray matter while the mean T(1) value of the BOLD activation pixels is close to the T(1) range of blood and cerebrospinal fluid. Copyright 2001 John Wiley & Sons, Ltd.

The thermal state of the Arabian plate derived from heat flow measurements in Oman and Yemen

NASA Astrophysics Data System (ADS)

Rolandone, Frederique; Lucazeau, Francis; Leroy, Sylvie; Mareschal, Jean-Claude; Jorand, Rachel; Goutorbe, Bruno; Bouquerel, Hélène

2013-04-01

The dynamics of the Afar plume and the rifting of the Red Sea and the Gulf of Aden affect the present-day thermal regime of the Arabian plate. However, the Arabian plate is a Precambrian shield covered on its eastern part by a Phanerozoic platform and its thermal regime, before the plume and rifting activities, should be similar to that of other Precambrian shields with a thick and stable lithosphere. The first heat flow measurements in the shield, in Saudi Arabia, yielded low values (35-44 mW/m2), similar to the typical shields values. Recent heat flow measurements in Jordan indicate higher values (56-66 mW/m2). As part of the YOCMAL project (YOung Conjugate MArgins Laboratory), we have conducted heat flow measurements in southern and northern Oman to obtain 10 new heat flux values in the eastern Arabian plate. We also derived 20 heat flux values in Yemen and Oman by processing thermal data from oil exploration wells. The surface heat flux in these different locations is uniformly low (45 mW/m2). The heat production in samples from the Dhofar and Socotra Precambrian basement is also low (0.7 µW/m3). Differences in heat flow between the eastern (60 mW/m2) and the western (45 mW/m2) parts of Arabia reflect differences in crustal heat production as well as a higher mantle heat flux in the west. We have calculated a steady state geotherm for the Arabian platform that intersects the isentropic temperature profile at a depth of about 150 km, consistent with the seismic observations. Seismic tomography studies of the mantle beneath Arabia also show this east-west contrast. Seismic studies have shown that the lithosphere is rather thin, 100 km or less below the shield and 150 km below the platform. The lithospheric thickness for the Arabian plate is 150 km, and the progressive thinning near the Red Sea, caused by the thermal erosion of the plume material, is too recent to be detected at the surface. The Afar plume mostly affects the base of the Arabian lithosphere along the Red Sea and the western part of the Gulf of Aden. The extent of this effect is explained by channeling of the asthenospheric magma by the rift. The subdued penetration into the Gulf of Aden is probably due to the important segmentation of the rift. The continental domain is not affected by rifting in the Gulf of Aden. The main thermal effect of the Arabian plate is probably the channeling of the Afar plume to the North.

Precision diamond grinding of ceramics and glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, S.; Paul, H.; Scattergood, R.O.

A new research initiative will be undertaken to investigate the effect of machine parameters and material properties on precision diamond grinding of ceramics and glass. The critical grinding depth to initiate the plastic flow-to-brittle fracture regime will be directly measured using plunge-grind tests. This information will be correlated with machine parameters such as wheel bonding and diamond grain size. Multiaxis grinding tests will then be made to provide data more closely coupled with production technology. One important aspect of the material property studies involves measuring fracture toughness at the very short crack sizes commensurate with grinding damage. Short crack toughnessmore » value`s can be much less than the long-crack toughness values measured in conventional fracture tests.« less

Semihard scattering unraveled from collective dynamics by two-pion azimuthal correlations in 158A GeV/c Pb+Au collisions.

PubMed

Agakichiev, G; Appelshäuser, H; Baur, R; Bielcikova, J; Braun-Munzinger, P; Cherlin, A; Drees, A; Esumi, S I; Filimonov, K; Fraenkel, Z; Fuchs, Ch; Glässel, P; Hering, G; Huovinen, P; Lenkeit, B; Marín, A; Messer, F; Messer, M; Milosevic, J; Miśkowiec, D; Nix, O; Panebrattsev, Yu; Petrácek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Razin, S; Rehak, P; Sako, H; Saveljic, N; Schmitz, W; Shimansky, S; Socol, E; Specht, H J; Stachel, J; Tilsner, H; Tserruya, I; Voigt, C; Voloshin, S; Weber, C; Wessels, J P; Wurm, J P; Yurevich, V

2004-01-23

Elliptic flow and two-particle azimuthal correlations of charged hadrons and high-p(T) pions (p(T)>1 GeV/c) have been measured close to midrapidity in 158A GeV/c Pb+Au collisions by the CERES experiment. Elliptic flow (v(2)) rises linearly with p(T) to a value of about 10% at 2 GeV/c. Beyond p(T) approximately 1.5 GeV/c, the slope decreases considerably, possibly indicating a saturation of v(2) at high p(T). Two-pion azimuthal anisotropies for p(T)>1.2 GeV/c exceed the elliptic flow values by about 60% in midcentral collisions. These nonflow contributions are attributed to nearside and back-to-back jetlike correlations, the latter exhibiting centrality dependent broadening.

Novel Non-invasive Estimation of Coronary Blood Flow using Contrast Advection in Computed Tomography Angiography

NASA Astrophysics Data System (ADS)

Eslami, Parastou; Seo, Jung-Hee; Rahsepar, Amirali; George, Richard; Lardo, Albert; Mittal, Rajat

2014-11-01

Coronary computed tomography angiography (CTA) is a promising tool for assessment of coronary stenosis and plaque burden. Recent studies have shown the presence of axial contrast concentration gradients in obstructed arteries, but the mechanism responsible for this phenomenon is not well understood. We use computational fluid dynamics to study intracoronary contrast dispersion and the correlation of concentration gradients with intracoronary blood flow and stenotic severity. Data from our CFD patient-specific simulations reveals that contrast dispersions are generated by intracoronary advection effects, and therefore, encode the coronary flow velocity. This novel method- Transluminal Attenuation Flow Encoding (TAFE) - is used to estimate the flowrate in phantom studies as well as preclinical experiments. Our results indicate a strong correlation between the values estimated from TAFE and the values measured in these experiments. The flow physics of contrast dispersion associated with TAFE will be discussed. This work is funded by grants from Coulter Foundation and Maryland Innovation Initiative. The authors have pending patents in this technology and RM and ACL have other financial interests associated with TAFE.

Resistance within hemodialysis shunts predicts patency.

PubMed

Bui, Trung D; Gordon, Ian L; Parashar, Amish; Vo, David; Wilson, Samuel E

2006-01-01

The authors examined the relationship between patency after thrombectomy of clotted dialysis grafts and intraoperative measurements of flow (Q), pressure gradient (PGR), and longitudinal resistance (RL). Eighteen thrombosed arteriovenous (AV) grafts underwent 21 thrombectomies. Pressures at arterial (P1) and venous (P2) ends of the AV grafts were determined with 22-gauge catheters and standard transducers; flow was measured with transit-time probes; arithmetic averaging of waveforms was used to compute mean Q, PGR, and RL. Kaplan-Meier patency curves were analyzed by using log rank methods. Mean patency for all grafts was 164 +/-152 days. For each variable, the 21 measurements were split and the patency curve for the grafts with the 11 lowest value grafts was compared to the curve representing the 10 highest value grafts. The difference between high RL versus low RL patency curves was significant with high-resistance grafts having a median patency of 55 days and low-resistance grafts having a median patency greater than 151 days (p = 0.0089). In contrast, the high Q group median patency was 151 days versus 174 days for the low Q group (p = 0.86). Median patency for the low PGR group was 115 days compared to 62 days for the high PGR group (p = 0.162). Longitudinal resistance within AV grafts, but not flow or pressure gradient, showed a significant correlation with patency after thrombectomy. Increased resistance to flow within AV grafts appears to be an important factor affecting the propensity of dialysis grafts to thrombose.

Heat as a tracer to estimate dissolved organic carbon flux from a restored wetland

USGS Publications Warehouse

Burow, K.R.; Constantz, J.; Fujii, R.

2005-01-01

Heat was used as a natural tracer to characterize shallow ground water flow beneath a complex wetland system. Hydrogeologic data were combined with measured vertical temperature profiles to constrain a series of two-dimensional, transient simulations of ground water flow and heat transport using the model code SUTRA (Voss 1990). The measured seasonal temperature signal reached depths of 2.7 m beneath the pond. Hydraulic conductivity was varied in each of the layers in the model in a systematic manual calibration of the two-dimensional model to obtain the best fit to the measured temperature and hydraulic head. Results of a series of representative best-fit simulations represent a range in hydraulic conductivity values that had the best agreement between simulated and observed temperatures and that resulted in simulated pond seepage values within 1 order of magnitude of pond seepage estimated from the water budget. Resulting estimates of ground water discharge to an adjacent agricultural drainage ditch were used to estimate potential dissolved organic carbon (DOC) loads resulting from the restored wetland. Estimated DOC loads ranged from 45 to 1340 g C/(m2 year), which is higher than estimated DOC loads from surface water. In spite of the complexity in characterizing ground water flow in peat soils, using heat as a tracer provided a constrained estimate of subsurface flow from the pond to the agricultural drainage ditch. Copyright ?? 2005 National Ground Water Association.

Hg isotopes reveal in-stream processing and legacy inputs in East Fork Poplar Creek, Oak Ridge, Tennessee, USA

DOE PAGES

Demers, Jason D.; Blum, Joel D.; Brooks, Scott C.; ...

2018-03-01

In this paper, natural abundance stable Hg isotope measurements were used to place new constraints on sources, transport, and transformations of Hg along the flow path of East Fork Poplar Creek (EFPC), a point-source contaminated headwater stream in Oak Ridge, Tennessee. Particulate-bound Hg in the water column of EFPC within the Y-12 National Security Complex, was isotopically similar to average metallic Hg(0) used in industry, having a mean δ 202Hg value of -0.42 ± 0.09‰ (1SD) and near-zero Δ 199Hg. On average, particulate fraction δ 202Hg values increased downstream by 0.53‰, while Δ 199Hg decreased by -0.10‰, converging with themore » Hg isotopic composition of the fine fraction of streambed sediment along the 26 km flow path. The dissolved fraction behaved differently. Although initial Δ 199Hg values of the dissolved fraction were also near-zero, these values increased transiently along the flow path. Initial δ 202Hg values of the dissolved fraction were more variable than in the particulate fraction, ranging from -0.44 to 0.18‰ among three seasonal sampling campaigns, but converged to an average δ 202Hg value of 0.01 ± 0.10‰ (1SD) downstream. Dissolved Hg in the hyporheic and riparian pore water had higher and lower δ 202Hg values, respectively, compared to dissolved Hg in stream water. Finally, variations in Hg isotopic composition of the dissolved and suspended fractions along the flow path suggest that: (1) physical processes such as dilution and sedimentation do not fully explain decreases in total mercury concentrations along the flow path; (2) in-stream processes include photochemical reduction, but microbial reduction is likely more dominant; and (3) additional sources of dissolved mercury inputs to EFPC at baseflow during this study predominantly arise from the hyporheic zone.« less

Hg isotopes reveal in-stream processing and legacy inputs in East Fork Poplar Creek, Oak Ridge, Tennessee, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demers, Jason D.; Blum, Joel D.; Brooks, Scott C.

In this paper, natural abundance stable Hg isotope measurements were used to place new constraints on sources, transport, and transformations of Hg along the flow path of East Fork Poplar Creek (EFPC), a point-source contaminated headwater stream in Oak Ridge, Tennessee. Particulate-bound Hg in the water column of EFPC within the Y-12 National Security Complex, was isotopically similar to average metallic Hg(0) used in industry, having a mean δ 202Hg value of -0.42 ± 0.09‰ (1SD) and near-zero Δ 199Hg. On average, particulate fraction δ 202Hg values increased downstream by 0.53‰, while Δ 199Hg decreased by -0.10‰, converging with themore » Hg isotopic composition of the fine fraction of streambed sediment along the 26 km flow path. The dissolved fraction behaved differently. Although initial Δ 199Hg values of the dissolved fraction were also near-zero, these values increased transiently along the flow path. Initial δ 202Hg values of the dissolved fraction were more variable than in the particulate fraction, ranging from -0.44 to 0.18‰ among three seasonal sampling campaigns, but converged to an average δ 202Hg value of 0.01 ± 0.10‰ (1SD) downstream. Dissolved Hg in the hyporheic and riparian pore water had higher and lower δ 202Hg values, respectively, compared to dissolved Hg in stream water. Finally, variations in Hg isotopic composition of the dissolved and suspended fractions along the flow path suggest that: (1) physical processes such as dilution and sedimentation do not fully explain decreases in total mercury concentrations along the flow path; (2) in-stream processes include photochemical reduction, but microbial reduction is likely more dominant; and (3) additional sources of dissolved mercury inputs to EFPC at baseflow during this study predominantly arise from the hyporheic zone.« less

Scalar Dissipation Modeling for Passive and Active Scalars: a priori Study Using Direct Numerical Simulation

NASA Technical Reports Server (NTRS)

Selle, L. C.; Bellan, Josette

2006-01-01

Transitional databases from Direct Numerical Simulation (DNS) of three-dimensional mixing layers for single-phase flows and two-phase flows with evaporation are analyzed and used to examine the typical hypothesis that the scalar dissipation Probability Distribution Function (PDF) may be modeled as a Gaussian. The databases encompass a single-component fuel and four multicomponent fuels, two initial Reynolds numbers (Re), two mass loadings for two-phase flows and two free-stream gas temperatures. Using the DNS calculated moments of the scalar-dissipation PDF, it is shown, consistent with existing experimental information on single-phase flows, that the Gaussian is a modest approximation of the DNS-extracted PDF, particularly poor in the range of the high scalar-dissipation values, which are significant for turbulent reaction rate modeling in non-premixed flows using flamelet models. With the same DNS calculated moments of the scalar-dissipation PDF and making a change of variables, a model of this PDF is proposed in the form of the (beta)-PDF which is shown to approximate much better the DNS-extracted PDF, particularly in the regime of the high scalar-dissipation values. Several types of statistical measures are calculated over the ensemble of the fourteen databases. For each statistical measure, the proposed (beta)-PDF model is shown to be much superior to the Gaussian in approximating the DNS-extracted PDF. Additionally, the agreement between the DNS-extracted PDF and the (beta)-PDF even improves when the comparison is performed for higher initial Re layers, whereas the comparison with the Gaussian is independent of the initial Re values. For two-phase flows, the comparison between the DNS-extracted PDF and the (beta)-PDF also improves with increasing free-stream gas temperature and mass loading. The higher fidelity approximation of the DNS-extracted PDF by the (beta)-PDF with increasing Re, gas temperature and mass loading bodes well for turbulent reaction rate modeling.

An Experiment to Introduce Mass Transfer Concepts Using a Commercial Hollow Fiber Blood Oxygenator

ERIC Educational Resources Information Center

McIver, Keith; Merrill, Thomas; Farrell, Stephanie

2017-01-01

A commercial hollow fiber blood oxygenation laboratory experiment was used to introduce lower level engineering students to mass balances in a two-phase system. Using measured values of concentration and flow rate, students calculated the rate of mass transfer from the gas phase and into the liquid phase, and compared the two values to determine…

48-hours administration of fenoterol in spontaneous preterm labor - does it affect fetal preload?

PubMed

Grzesiak, Mariusz; Forys, Sebastian; Sobczak, Malgorzata; Ahmed, Rehana B; Wilczynski, Jan

2013-01-01

to investigate whether any changes in the preload index (PLI) occur within the first 48 hours of fenoterol intravenous tocolysis. Doppler evaluation of placental and fetal circulation was performed in 36 pregnant women prior to fenoterol administration and after 24/48 hours. Measurements were obtained from a longitudinal section of the inferior vena cava (IVC) and preload index was calculated. To determine changes over time, an all study variable analysis of variance (ANOVA) for repeated measurements, followed by Tukey-Kramer's multiple comparison test was used. The effects of additional clinical covariates were checked. The maternal heart rate values were significantly increased after 24 hours and 48 hours in comparison to pre-treatment values. No significant changes in fetal heart rate were observed during treatment. The fetal IVC PLI values were significantly reduced after 24 hours and 48 hours of treatment. The increase in PLI values when comparing 24 and 48 hours results were not statistically significant. These observations were consistent with ANOVA post-hoc analysis. 48 hours intravenous administration of fenoterol appears not to alter inferior vena cava blood flow by itself. The reduction in PLI values may reflect lower fetal preload conditions during the course of successful tocolytic treatment. Therefore, Doppler IVC PLI measurement should be considered as a possible additional assessment method of effectiveness of treatment. However, other Doppler venous blood flow parameters should be assessed to confirm the results and clarify whether maternal corticosteroids administration may be interfering with the results.

Evidence of equilibrium peak runoff rates in steep tropical terrain on the island of Dominica during Tropical Storm Erika, August 27, 2015

NASA Astrophysics Data System (ADS)

Ogden, Fred L.

2016-11-01

Tropical Storm Erika was a weakly organized tropical storm when its center of circulation passed more than 150 km north of the island of Dominica on August 27, 2015. Hurricane hunter flights had difficulty finding the center of circulation as the storm encountered a high shear environment. Satellite and radar observations showed gyres imbedded within the broader circulation. Radar observations from Guadeloupe show that one of these gyres formed in convergent mid-level flow triggered by orographic convection over the island of Dominica. Gauge-adjusted radar rainfall data indicated between 300 and 750 mm of rainfall on Dominica, most of it over a four hour period. The result was widespread flooding, destruction of property, and loss of life. The extremity of the rainfall on steep watersheds covered with shallow soils was hypothesized to result in near-equilibrium runoff conditions where peak runoff rates equal the watershed-average peak rainfall rate minus a small constant loss rate. Rain gauge adjusted radar rainfall estimates and indirect peak discharge (IPD) measurements from 16 rivers at watershed areas ranging from 0.9 to 31.4 km2 using the USGS Slope-Area method allowed testing of this hypothesis. IPD measurements were compared against the global envelope of maximum observed flood peaks versus drainage area and against simulations using the U.S. Army Corps of Engineers Gridded Surface/Subsurface Hydrologic Analysis (GSSHA) model to detect landslide-affected peak flows. Model parameter values were estimated from the literature. Reasonable agreement was found between GSSHA simulated peak flows and IPD measurements in some watersheds. Results showed that landslide dam failure affected peak flows in 5 of the 16 rivers, with peak flows significantly greater than the envelope curve values for the flood of record for like-sized watersheds on the planet. GSSHA simulated peak discharges showed that the remaining 11 peak flow values were plausible. Simulations of an additional 24 watersheds ranging in size from 2.2 to 75.4 km2 provided confirmation that the IPD measurements varied from 40 to nearly 100% of the envelope curve value depending on storm-total rainfall. Results presented in this paper support the hypothesis that on average, the peak discharges scaled linearly with drainage area, and the constant of proportionality was equivalent to 134 mm h-1, or a unit discharge of 37.22 m3 s-1 km-2. The results also indicate that after the available watershed storage was filled after approximately 450-500 mm of rain fell, runoff efficiencies exceeded 50-60%, and peak runoff rates were more than 80% of the peak rainfall rate minus a small constant loss rate of 20 mm h-1. These findings have important implications for design of resilient infrastructure, and means that rainfall rate was the primary determinant of peak flows once the available storage was filled in the absences of landslide dam failure.

Computations of Flow over a Hump Model Using Higher Order Method with Turbulence Modeling

NASA Technical Reports Server (NTRS)

Balakumar, P.

2005-01-01

Turbulent separated flow over a two-dimensional hump is computed by solving the RANS equations with k - omega (SST) turbulence model for the baseline, steady suction and oscillatory blowing/suction flow control cases. The flow equations and the turbulent model equations are solved using a fifth-order accurate weighted essentially. nonoscillatory (WENO) scheme for space discretization and a third order, total variation diminishing (TVD) Runge-Kutta scheme for time integration. Qualitatively the computed pressure distributions exhibit the same behavior as those observed in the experiments. The computed separation regions are much longer than those observed experimentally. However, the percentage reduction in the separation region in the steady suction case is closer to what was measured in the experiment. The computations did not predict the expected reduction in the separation length in the oscillatory case. The predicted turbulent quantities are two to three times smaller than the measured values pointing towards the deficiencies in the existing turbulent models when they are applied to strong steady/unsteady separated flows.

High throughput, parallel imaging and biomarker quantification of human spermatozoa by ImageStream flow cytometry.

PubMed

Buckman, Clayton; George, Thaddeus C; Friend, Sherree; Sutovsky, Miriam; Miranda-Vizuete, Antonio; Ozanon, Christophe; Morrissey, Phil; Sutovsky, Peter

2009-12-01

Spermatid specific thioredoxin-3 protein (SPTRX-3) accumulates in the superfluous cytoplasm of defective human spermatozoa. Novel ImageStream technology combining flow cytometry with cell imaging was used for parallel quantification and visualization of SPTRX-3 protein in defective spermatozoa of five men from infertile couples. The majority of the SPTRX-3 containing cells were overwhelmingly spermatozoa with a variety of morphological defects, detectable in the ImageStream recorded images. Quantitative parameters of relative SPTRX-3 induced fluorescence measured by ImageStream correlated closely with conventional flow cytometric measurements of the same sample set and reflected the results of clinical semen evaluation. Image Stream quantification of SPTRX-3 combines and surpasses the informative value of both conventional flow cytometry and light microscopic semen evaluation. The observed patterns of the retention of SPTRX-3 in the sperm samples from infertility patients support the view that SPTRX3 is a biomarker of male infertility.

Acoustic structure and propagation in highly porous, layered, fibrous materials

NASA Technical Reports Server (NTRS)

Lambert, R. F.; Tesar, J. S.

1984-01-01

The acoustic structure and propagation of sound in highly porous, layered, fine fiber materials is examined. Of particular interest is the utilization of the Kozeny number for determining the static flow resistance and the static structure factor based on flow permeability measurements. In this formulation the Kozeny number is a numerical constant independent of volume porosity at high porosities. The other essential parameters are then evaluated employing techniques developed earlier for open cell foams. The attenuation and progressive phase characteristics in bulk samples are measured and compared with predicted values. The agreements on the whole are very satisfactory.

Flow Transitions in a Rotating Magnetic Field

NASA Technical Reports Server (NTRS)

Volz, M. P.; Mazuruk, K.

1996-01-01

Critical Rayleigh numbers have been measured in a liquid metal cylinder of finite height in the presence of a rotating magnetic field. Several different stability regimes were observed, which were determined by the values of the Rayleigh and Hartmann numbers. For weak rotating magnetic fields and small Rayleigh numbers, the experimental observations can be explained by the existence of a single non-axisymmetric meridional roll rotating around the cylinder, driven by the azimuthal component of the magnetic field. The measured dependence of rotational velocity on magnetic field strength is consistent with the existence of laminar flow in this regime.

Oil release from Macondo well MC252 following the Deepwater Horizon accident.

PubMed

Griffiths, Stewart K

2012-05-15

Oil flow rates and cumulative discharge from the BP Macondo Prospect well in the Gulf of Mexico are calculated using a physically based model along with wellhead pressures measured at the blowout preventer (BOP) over the 86-day period following the Deepwater Horizon accident. Parameters appearing in the model are determined empirically from pressures measured during well shut-in and from pressures and flow rates measured the preceding day. This methodology rigorously accounts for ill-characterized evolution of the marine riser, installation and removal of collection caps, and any erosion at the wellhead. The calculated initial flow rate is 67,100 stock-tank barrels per day (stbd), which decays to 54,400 stbd just prior to installation of the capping stack and subsequent shut-in. The calculated cumulative discharge is 5.4 million stock-tank barrels, of which 4.6 million barrels entered the Gulf. Quantifiable uncertainties in these values are -9.3% and +7.5%, yielding a likely total discharge in the range from 4.9 to 5.8 million barrels. Minimum and maximum credible values of this discharge are 4.6 and 6.2 million barrels. Alternative calculations using the reservoir and sea-floor pressures indicate that any erosion within the BOP had little affect on cumulative discharge.

Analyzing land surface temperature variations during Fogo Island (Cape Verde) 2014-2015 eruption with Landsat 8 images

NASA Astrophysics Data System (ADS)

Vieira, D.; Teodoro, A.; Gomes, A.

2016-10-01

Land Surface Temperature (LST) is an important parameter related to land surface processes that changes continuously through time. Assessing its dynamics during a volcanic eruption has both environmental and socio-economical interest. Lava flows and other volcanic materials produced and deposited throughout an eruption transform the landscape, contributing to its heterogeneity and altering LST measurements. This paper aims to assess variations of satellite-derived LST and to detect patterns during the latest Fogo Island (Cape Verde) eruption, extending from November 2014 through February 2015. LST data was obtained through four processed Landsat 8 images, focused on the caldera where Pico do Fogo volcano sits. QGIS' plugin Semi-Automatic Classification was used in order to apply atmospheric corrections and radiometric calibrations. The algorithm used to retrieve LST values is a single-channel method, in which emissivity values are known. The absence of in situ measurements is compensated by the use of MODIS sensor-derived LST data, used to compare with Landsat retrieved measurements. LST data analysis shows as expected that the highest LST values are located inside the caldera. High temperature values were also founded on the south-facing flank of the caldera. Although spatial patterns observed on the retrieved data remained roughly the same during the time period considered, temperature values changed throughout the area and over time, as it was also expected. LST values followed the eruption dynamic experiencing a growth followed by a decline. Moreover, it seems possible to recognize areas affected by lava flows of previous eruptions, due to well-defined LST spatial patterns.

Azimuthal anisotropy distributions in high-energy collisions

NASA Astrophysics Data System (ADS)

Yan, Li; Ollitrault, Jean-Yves; Poskanzer, Arthur M.

2015-03-01

Elliptic flow in ultrarelativistic heavy-ion collisions results from the hydrodynamic response to the spatial anisotropy of the initial density profile. A long-standing problem in the interpretation of flow data is that uncertainties in the initial anisotropy are mingled with uncertainties in the response. We argue that the non-Gaussianity of flow fluctuations in small systems with large fluctuations can be used to disentangle the initial state from the response. We apply this method to recent measurements of anisotropic flow in Pb+Pb and p+Pb collisions at the LHC, assuming linear response to the initial anisotropy. The response coefficient is found to decrease as the system becomes smaller and is consistent with a low value of the ratio of viscosity over entropy of η / s ≃ 0.19. Deviations from linear response are studied. While they significantly change the value of the response coefficient they do not change the rate of decrease with centrality. Thus, we argue that the estimate of η / s is robust against non-linear effects.

Entrainment in Laboratory Simulations of Cumulus Cloud Flows

NASA Astrophysics Data System (ADS)

Narasimha, R.; Diwan, S.; Subrahmanyam, D.; Sreenivas, K. R.; Bhat, G. S.

2010-12-01

A variety of cumulus cloud flows, including congestus (both shallow bubble and tall tower types), mediocris and fractus have been generated in a water tank by simulating the release of latent heat in real clouds. The simulation is achieved through ohmic heating, injected volumetrically into the flow by applying suitable voltages between diametral cross-sections of starting jets and plumes of electrically conducting fluid (acidified water). Dynamical similarity between atmospheric and laboratory cloud flows is achieved by duplicating values of an appropriate non-dimensional heat release number. Velocity measurements, made by laser instrumentation, show that the Taylor entrainment coefficient generally increases just above the level of commencement of heat injection (corresponding to condensation level in the real cloud). Subsequently the coefficient reaches a maximum before declining to the very low values that characterize tall cumulus towers. The experiments also simulate the protected core of real clouds. Cumulus Congestus : Atmospheric cloud (left), simulated laboratory cloud (right). Panels below show respectively total heat injected and vertical profile of heating in the laboratory cloud.

Distribution of extravascular fluid volumes in isolated perfused lungs measured with H215O.

PubMed Central

Jones, T; Jones, H A; Rhodes, C G; Buckingham, P D; Hughes, J M

1976-01-01

The distributions per unit volume of extravascular water (EVLW), blood volume, and blood flow were measured in isolated perfused vertical dog lungs. A steady-state tracer technique was employed using oxygen-15, carbon-11, and nitrogen-13 isotopes and external scintillation counting of the 511-KeV annihilation radiation common to all three radionuclides. EVLW, and blood volume and flow increased from apex to base in all preparations, but the gradient of increasing flow exceeded that for blood and EVLW volumes. The regional distributions of EVLW and blood volume were almost identical. With increasing edema, lower-zone EVLW increased slightly relative to that in the upper zone. There was no change in the distribution of blood volume or flow until gross edema (100% wt gain) occurred when lower zone values were reduced. In four lungs the distribution of EVLW was compared with wet-to-dry ratios from lung biopsies taken immediately afterwards. Whereas the isotopically measured EVLW increased from apex to base, the wet-to-dry weight ratios remained essentially uniform. We concluded that isotopic methods measure only an "exchangeable" water pool whose volume is dependent on regional blood flow and capillary recruitment. Second, the isolated perfused lung can accommodate up to 60% wt gain without much change in the regional distribution of EVLW, volume, or flow. PMID:765354

Resonant Doppler velocimeter. Ph.D. Thesis. Final Report, 1 Jul. 1974 - 31 Oct. 1979; [velocity, temperature, and pressure measurement

NASA Technical Reports Server (NTRS)

Zimmermann, M.

1980-01-01

A technique is presented for visualizing and quantitatively measuring velocity, temperature, and pressure by shining a single frequency laser beam into a gaseous flow which is seeded with an atomic species. The laser is tuned through the absorption frequencies of the seeded species and the absorption profile is detected by observing fluorescence as the atoms relax back to the ground state. The flow velocity is determined by observing the Doppler shift in the absorption frequency. Spectroscopic absorption line broadening mechanisms furnish information regarding the static temperature and pressure of the moving gas. Results of experiments conducted in the free stream and in the bow shock of a conical model mounted in a hypersonic wind tunnel indicate that the experimental uncertainties in the measurement of average values for the velocity, temperature and pressure of the flow are 0.1, 5 and 10 percent respectively.

Simultaneous three-dimensional velocity and mixing measurements by use of laser Doppler velocimetry and fluorescence probes in a water tunnel

NASA Technical Reports Server (NTRS)

Neuhart, Dan H.; Wing, David J.; Henderson, Uleses C., Jr.

1994-01-01

A water tunnel investigation was conducted to demonstrate the capabilities of a laser-based instrument that can measure velocity and fluorescence intensity simultaneously. Fluorescence intensity of an excited fluorescent dye is directly related to concentration level and is used to indicate the extent of mixing in flow. This instrument is a three-dimensional laser Doppler velocimeter (LDV) in combination with a fluorometer for measuring fluorescence intensity variations. This capability allows simultaneous flow measurements of the three orthogonal velocity components and mixing within the same region. Two different flows which were generated by two models were studied: a generic nonaxisymmetric nozzle propulsion simulation model with an auxiliary internal water source that generated a jet flow and an axisymmetric forebody model with a circular sector strake that generated a vortex flow. The off-body flow fields around these models were investigated in the Langley 16- by 24-Inch Water Tunnel. The experimental results were used to calculate 17 quantities that included mean and fluctuating velocities, Reynolds stresses, mean and fluctuating dye fluorescence intensities (proportional to concentration), and fluctuating velocity and dye concentration correlations. An uncertainty analysis was performed to establish confidence levels in the experimental results. In general, uncertainties in mean velocities varied between 1 and 7 percent of free-stream velocity; uncertainties in fluctuating velocities varied between 1 and 5 percent of reference values. The results show characteristics that are unique to each type of flow.

Improving catchment discharge predictions by inferring flow route contributions from a nested-scale monitoring and model setup

NASA Astrophysics Data System (ADS)

van der Velde, Y.; Rozemeijer, J. C.; de Rooij, G. H.; van Geer, F. C.; Torfs, P. J. J. F.; de Louw, P. G. B.

2011-03-01

Identifying effective measures to reduce nutrient loads of headwaters in lowland catchments requires a thorough understanding of flow routes of water and nutrients. In this paper we assess the value of nested-scale discharge and groundwater level measurements for the estimation of flow route volumes and for predictions of catchment discharge. In order to relate field-site measurements to the catchment-scale an upscaling approach is introduced that assumes that scale differences in flow route fluxes originate from differences in the relationship between groundwater storage and the spatial structure of the groundwater table. This relationship is characterized by the Groundwater Depth Distribution (GDD) curve that relates spatial variation in groundwater depths to the average groundwater depth. The GDD-curve was measured for a single field site (0.009 km2) and simple process descriptions were applied to relate groundwater levels to flow route discharges. This parsimonious model could accurately describe observed storage, tube drain discharge, overland flow and groundwater flow simultaneously with Nash-Sutcliff coefficients exceeding 0.8. A probabilistic Monte Carlo approach was applied to upscale field-site measurements to catchment scales by inferring scale-specific GDD-curves from the hydrographs of two nested catchments (0.4 and 6.5 km2). The estimated contribution of tube drain effluent (a dominant source for nitrates) decreased with increasing scale from 76-79% at the field-site to 34-61% and 25-50% for both catchment scales. These results were validated by demonstrating that a model conditioned on nested-scale measurements improves simulations of nitrate loads and predictions of extreme discharges during validation periods compared to a model that was conditioned on catchment discharge only.

Water velocity and the nature of critical flow in large rapids on the Colorado River, Utah

USGS Publications Warehouse

Magirl, Christopher S.; Gartner, Jeffrey W.; Smart, Graeme M.; Webb, Robert H.

2009-01-01

Rapids are an integral part of bedrock‐controlled rivers, influencing aquatic ecology, geomorphology, and recreational value. Flow measurements in rapids and high‐gradient rivers are uncommon because of technical difficulties associated with positioning and operating sufficiently robust instruments. In the current study, detailed velocity, water surface, and bathymetric data were collected within rapids on the Colorado River in eastern Utah. With the water surface survey, it was found that shoreline‐based water surface surveys may misrepresent the water surface slope along the centerline of a rapid. Flow velocities were measured with an ADCP and an electronic pitot‐static tube. Integrating multiple measurements, the ADCP returned velocity data from the entire water column, even in sections of high water velocity. The maximum mean velocity measured with the ADCP was 3.7 m/s. The pitot‐static tube, while capable of only point measurements, quantified velocity 0.39 m below the surface. The maximum mean velocity measured with the pitot tube was 5.2 m/s, with instantaneous velocities up to 6.5 m/s. Analysis of the data showed that flow was subcritical throughout all measured rapids with a maximum measured Froude number of 0.7 in the largest measured rapids. Froude numbers were highest at the entrance of a given rapid, then decreased below the first breaking waves. In the absence of detailed bathymetric and velocity data, the Froude number in the fastest‐flowing section of a rapid was estimated from near‐surface velocity and depth soundings alone.

Model for predicting peak expiratory flow rate of Nigerian workers in a cement factory in Itori, Ogun State, Nigeria.

PubMed

Ismaila, Salami Olasunkanmi; Akanbi, Olusegun Gabriel; Olaoniye, Wasiu

2015-01-01

The main aim of the study was to propose a model for predicting the peak expiratory flow rate (PEFR) of Nigerian workers in a cement factory. Sixty randomly selected non-smoker and healthy workers (30 in production sections, 30 in the administrative section of the factory) participated in the study. Their physical characteristics and PEFR were measured. Multiple correlations using SPSS version 16.0 were performed on the data. The values of PEFR, using the obtained model, were compared with the measured values using a two-tailed t test. There were positive correlations among age, height and PEFR. A prediction equation for PEFR based on age, height, weight and years of exposure (experience) was obtained with R² = .843 (p < 0.001). The developed model will be useful for the management in determining PEFR of workers in the cement industry for possible medical attention.

Doppler aortic flow velocity measurement in healthy children.

PubMed Central

Sohn, S.; Kim, H. S.

2001-01-01

To determine normal values for Doppler parameters of left ventricular function, ascending aortic blood flow velocity was measured by pulsed wave Doppler echocardiography in 63 healthy children with body surface area (BSA) < 1 m(2) (age < 10 yr). Peak velocity was independent of sex, but increased with body size. Mean acceleration was related to peak velocity (r = 0.75, p < 0.0001). Both stroke distance and ejection time had strong negative correlations with heart rate and positive correlations with BSA, suggesting that these parameters should be evaluated in relation to heart rate and body size. Mean intra- and interobserver variability for peak velocity, ejection time, stroke and minute distance ranged from 3 to 7%, whereas variability for acceleration time was 9 to 13%. These data may be used as reference values for the assessment of hemodynamic states in young children with cardiac disease. PMID:11306737

Time of travel and dispersion in a selected reach of Roberts Creek, Clayton County, Iowa

USGS Publications Warehouse

Kolpin, D.W.; Kalkhoff, S.J.

1992-01-01

Time of travel was determined by dye tracing, using rhodamine WT as the tracer. One dyeinjection site and three sampling sites were used to measure time of travel. Two dye-tracing tests were conducted at discharges having flow-duration values of 48 and 80 percent. The discharges at the time of the two dye-tracing tests approximated medium- and low-flow conditions. The average stream velocity in the study area was 0.23 foot per second during medium-flow conditions, March 20 to 22,1990, and 0.07 foot per second during low-flow conditions, April 30 to May 12, 1990. The injected dye dispersed in a plume that lasted about 18 hours during medium flow and about 64 hours during low flow at the downstream site.

Three-Dimensional Navier-Stokes Simulation of Space Shuttle Main Propulsion 17-inch Disconnect Valves

NASA Technical Reports Server (NTRS)

Kandula, M.; Pearce, D. G.

1991-01-01

A steady incompressible three-dimensional viscous flow analysis has been conducted for the Space Shuttle external tank/orbiter propellant feed line disconnect flapper valves with upstream elbows. The Navier-Stokes code, INS3D, is modified to handle interior obstacles and a simple turbulence model. The flow solver is tested for stability and convergence in the presence of interior flappers. An under-relaxation scheme has been incorporated to improve the solution stability. Important flow characteristics such as secondary flows, recirculation, vortex and wake regions, and separated flows are observed. Computed values for forces, moments, and pressure drop are in satisfactory agreement with water flow test data covering a maximum tube Reynolds number of 3.5 million. The predicted hydrodynamical stability of the flappers correlates well with the measurements.

Effects of Elastoplastic Material Properties on Shallow Fault Slip and Surface Displacement Fields

NASA Astrophysics Data System (ADS)

Nevitt, J. M.; Brooks, B. A.; Minson, S. E.; Lockner, D. A.; Moore, D. E.; Ericksen, T. L.; Hudnut, K. W.; Glennie, C. L.; Madugo, C. M.

2016-12-01

A primary control on the geodynamics of rifting is the thermal regime. To better understand the geodynamics of rifting in the northern Gulf of California we systematically measured heat-flow across the Wagner Basin, a tectonically active basin that lies near the southern terminus of the Cerro Prieto fault. Seismic reflection profiles show sediment in excess of 5 s two-way travel time, implying a sediment thickness of > 7 km. The heat flow profile is 40 km long, has a nominal measurement spacing of 1 km, and is collocated with a seismic reflection profile. Heat flow measurements were made with a 6.5-m violin-bow probe. Most measurements are of good quality in that the probe fully penetrated sediments and measurements were stable enough to invert for heat flow and thermal properties. We have estimated corrections for environmental perturbations due to changes in bottom water temperature and sedimentation. The mean and standard deviation of heat flow across the western, central, and eastern parts of the basin are 220±60, 99±14, 1058±519 mW m-2, respectively. Corrections for sedimentation would increase measured heat flow across the central part of basin by 40 to 60%. We interpret the relatively high heat flow and large variability on the western and eastern flanks in terms of upward fluid flow at depth below the seafloor, whereas the lower and more consistent values across the central part of the basin are suggestive of conductive heat transfer. Based on an observed fault depth of 1.75 km we estimated the maximum Darcy velocities through the western and eastern flanks as 3 and 10 cm yr-1, respectively. Heat flow across the central basin is consistent with gabbroic underplating at a depth of 15 km and suggests that continental rupture here has not gone to completion.

Computer aided approximation of flow rate through systemic-pulmonary arterial shunts (SPAS).

PubMed

Vennemann, Peter; Montag, Michael; Peters, Franz; Merzkirch, Wolfgang

2012-02-22

The discrimination of flow rates through bronchial arteries that are affected by pathological SPAS today still happens solely qualitatively. A reproducible quantification of flow rates, however, would enable the comprehension of phenomena like the intensified shunt perfusion seen in cases of chronic inflammations or the characterization of SPAS that may cause cardiovascular problems. A computational program is developed, that allows the modeling of individual bronchial arteries on the basis of the information provided by angiography. Angiographic images are available from the standard clinical assessment of SPAS. The flow through continuous and geometrically measurable vessel segments and SPAS is given by the law of Hagen-Poiseuille. The discharge through healthy branches is calculated by means of allometric scaling laws. The simulation results are verified by flow experiments in artificial vessel networks made of glass and PE tubing. The experimental set-up mimics realistic, pulsating pressure and flow conditions. When applied to the artificial vessel networks, the model described herein provides results for the volumetric flow rate that differ from values measured in laboratory experiments by <6%. The computer model is also applied to real angiographic images. Due to inaccuracies during the deduction of the geometry and due to necessary simplifications of the model, we expect significant deviations between calculated and real flow rates in bronchial systems. Nevertheless, the presented method enables the physician to objectively estimate the order of magnitude of volumetric flow through individual SPAS fairly independently from his experience and without the need of measurements additional to the mandatory angiography.