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Sample records for abrasive flow rate

  1. Mass flow rate measurement in abrasive jets using acoustic emission

    NASA Astrophysics Data System (ADS)

    Ivantsiv, V.; Spelt, J. K.; Papini, M.

    2009-09-01

    The repeatability of abrasive jet machining operations is presently limited by fluctuations in the mass flow rate due to powder compaction, stratification and humidity effects. It was found that the abrasive mass flow rate for a typical abrasive jet micromachining setup could be determined by using data from the acoustic emission of the abrasive jet impacting a flat plate. Two methods for extracting the mass flow rate from the acoustic emission were developed and compared. In the first method, the number of particle impacts per unit time was determined by a direct count of peaks in the acoustic emission signal. The second method utilizes the power spectrum density of the acoustic emission in a specific frequency range. Both measures were found to correlate strongly with the mass flow rate measured by weighing samples of blasted powder for controlled time periods. It was found that the peak count method permits measurement of the average frequency of the impacts and the mass flow rate, but can only be applied to flow rates in which the impact frequency is approximately one order of magnitude less than the frequency of the target plate ringing. The power spectrum density method of signal processing is applicable to relatively fine powders and to flow rates at which the average impact frequency is of the same order of magnitude as that of the ringing due to the impact. The acoustic emission technique can be used to monitor particle flow variations over a wide range of time periods and provides a straightforward and accurate means of process control.

  2. Synthesis CNTs Particle Based Abrasive Media for Abrasive Flow Machining Process

    NASA Astrophysics Data System (ADS)

    Kumar, Sonu; Murtaza, Q.; Walia, R. S.; Dhull, S.; Tyagi, P. K.

    2016-02-01

    Abrasive flow machining (AFM) is a modem fine finishing process used for intricate and internal finishing of components or parts. It is based on flowing of viscoelastic abrasive media over the surface to be fine finished. The abrasive media is the important parameter in the AFM process because of its ability to accurately abrade the predefined area along it flow path. In this study, an attempt is made to develop a new abrasive, alumina with Carbon non tubes (CNTs) in viscoelastic medium. CNT s in house produced through chemical vapour deposition technique and characterize through TEM. Performance evaluation of the new abrasive media is carried out by increasing content of CNT s with fixed extrusion pressure, viscosity of media and media flow rate as process parameters and surface finish improvement and material removal as process responses in AFM setup. Significantly improvement has been observed in material removal and maximum improvement of 100% has been observed in the surface finish on the inner cylindrical surface of the cast iron work piece.

  3. Dry Flowing Abrasive Decontamination Technique for Pipe Systems with Swirling Air Flow

    SciTech Connect

    Kameo, Yutaka; Nakashima, Mikio; Hirabayashi, Takakuni

    2003-10-15

    A dry abrasive decontamination method was developed for removing radioactive corrosion products from surfaces of coolant pipe systems in decommissioning of a nuclear power plant. Erosion behavior of inside surfaces of stainless and carbon steel pipes by a swirling air flow containing alumina or cast-iron grit abrasive was studied. Erosion depths of the test pipes were approximately proportional to an abrasive concentration in air and an exponent of flow rate of airstream. The experimental results indicated that the present method could keep satisfactory erosion ability of abrasives even for a large-size pipe. The present method was successfully applied to {sup 60}Co-contaminated specimens sampled from a pipe of the water cleanup system of the Japan Power Demonstration Reactor.

  4. Nanometric Finishing on Biomedical Implants by Abrasive Flow Finishing

    NASA Astrophysics Data System (ADS)

    Subramanian, Kavithaa Thirumalai; Balashanmugam, Natchimuthu; Shashi Kumar, Panaghra Veeraiah

    2016-01-01

    Abrasive flow finishing (AFF) is a non-conventional finishing technique that offers better accuracy, efficiency, consistency, economy in finishing of complex/difficult to machine materials/components and provides the possibility of effective automation as aspired by the manufacturing sector. The present study describes the finishing of a hip joint made of ASTM grade Co-Cr alloy by Abrasive Flow Machining (AFM) process. The major input parameters of the AFF process were optimized for achieving nanometric finishing of the component. The roughness average (Ra) values were recorded during experimentation using surface roughness tester and the results are discussed in detail. The surface finished hip joints were characterized using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and residual stress analysis using X-Ray Diffraction (XRD). The discussion lays emphasis on the significance, efficacy and versatile nature of the AFF process in finishing of bio-medical implants.

  5. Can Wet Rocky Granular Flows Become Debris Flows Due to Fine Sediment Production by Abrasion?

    NASA Astrophysics Data System (ADS)

    Arabnia, O.; Sklar, L. S.; Bianchi, G.; Mclaughlin, M. K.

    2015-12-01

    Debris flows are rapid mass movements in which elevated pore pressures are sustained by a viscous fluid matrix with high concentrations of fine sediments. Debris flows may form from coarse-grained wet granular flows as fine sediments are entrained from hillslope and channel material. Here we investigate whether abrasion of the rocks within a granular flow can produce sufficient fine sediments to create debris flows. To test this hypothesis experimentally, we used a set of 4 rotating drums ranging from 0.2 to 4.0 m diameter. Each drum has vanes along the boundary ensure shearing within the flow. Shear rate was varied by changing drum rotational velocity to maintain a constant Froude Number across drums. Initial runs used angular clasts of granodiorite with a tensile strength of 7.6 MPa, with well-sorted coarse particle size distributions linearly scaled with drum radius. The fluid was initially clear water, which rapidly acquired fine-grained wear products. After each 250 m tangential distance, we measured the particle size distributions, and then returned all water and sediment to the drums for subsequent runs. We calculate particle wear rates using statistics of size and mass distributions, and by fitting the Sternberg equation to the rate of mass loss from the size fraction > 2mm. Abundant fine sediments were produced in the experiments, but very little change in the median grain size was detected. This appears to be due to clast rounding, as evidenced by a decrease in the number of stable equilibrium resting points. We find that the growth in the fine sediment concentration in the fluid scales with unit drum power. This relationship can be used to estimate fine sediment production rates in the field. We explore this approach at Inyo Creek, a steep catchment in the Sierra Nevada, California. There, a significant debris flow occurred in July 2013, which originated as a coarse-grained wet granular flow. We use surveys to estimate flow depth and velocity where super

  6. Seasonal-scale abrasion and quarrying patterns from a two-dimensional ice-flow model coupled to distributed and channelized subglacial drainage

    NASA Astrophysics Data System (ADS)

    Beaud, Flavien; Flowers, Gwenn E.; Pimentel, Sam

    2014-08-01

    Field data and numerical modeling show that glaciations have the potential either to enhance relief or to dampen topography. We aim to model the effect of the subglacial hydraulic system on spatiotemporal patterns of glacial erosion by abrasion and quarrying on time scales commensurate with drainage system fluctuations (e.g., seasonal to annual). We use a numerical model that incorporates a dual-morphology subglacial drainage system coupled to a higher-order ice-flow model and process-specific erosion laws. The subglacial drainage system allows for a dynamic transition between two morphologies: the distributed system, characterized by an increase in basal water pressure with discharge, and the channelized system, which exhibits a decrease in equilibrium water pressure with increasing discharge. We apply the model to a simple synthetic glacier geometry, drive it with prescribed meltwater input variations, and compute sliding and erosion rates over a seasonal cycle. When both distributed and channelized systems are included, abrasion and sliding maxima migrate ~ 20% up-glacier compared to simulations with distributed drainage only. Power-law sliding generally yields to a broader response of abrasion to water pressure changes along the flowline compared to Coulomb-friction sliding. Multi-day variations in meltwater input elicit a stronger abrasion response than either diurnal- or seasonal variations alone for the same total input volume. An increase in water input volume leads to increased abrasion. We find that ice thickness commensurate with ice sheet outlet glaciers can hinder the up-glacier migration of abrasion. Quarrying patterns computed with a recently published law differ markedly from calculated abrasion patterns, with effective pressure being a stronger determinant than sliding speeds of quarrying rates. These variations in calculated patterns of instantaneous erosion as a function of hydrology-, sliding-, and erosion-model formulation, as well as model

  7. The surface quality of AWJ cut parts as a function of abrasive material reusing rate

    NASA Astrophysics Data System (ADS)

    Schnakovszky, C.; Herghelegiu, E.; Radu, M. C.; Tampu, N. C.

    2015-11-01

    Abrasive water jet cutting (AWJ) has been extensively used during the last years to process a large variety of materials since it offers important advantages as a good quality of the processed surface, without heat affected zones, low environmental impact (no emission of dust or other compounds that endanger the health of the user), small induced mechanical stresses etc. The main disadvantage is the high cost of processing (cost of equipment and consumables). In view of this, the effects of reusing the abrasive material on the quality of processed surface are investigated in this paper. Two steel materials were used: OL 37 (S 235) with large applicability in machine building industry and 2P armor steel used in the arms industry. The reusing rate of the garnet abrasive material was: 0%, 20%, 40%, 60%, 80% and 100%. The quality of processed surface was quantified by the following parameters: width at the jet inlet (Li), width at the jet outlet (Lo), inclination angle (α), deviation from perpendicularity (u) and roughness (Ra).

  8. Theoretical study on removal rate and surface roughness in grinding a RB-SiC mirror with a fixed abrasive.

    PubMed

    Wang, Xu; Zhang, Xuejun

    2009-02-10

    This paper is based on a microinteraction principle of fabricating a RB-SiC material with a fixed abrasive. The influence of the depth formed on a RB-SiC workpiece by a diamond abrasive on the material removal rate and the surface roughness of an optical component are quantitatively discussed. A mathematical model of the material removal rate and the simulation results of the surface roughness are achieved. In spite of some small difference between the experimental results and the theoretical anticipation, which is predictable, the actual removal rate matches the theoretical prediction very well. The fixed abrasive technology's characteristic of easy prediction is of great significance in the optical fabrication industry, so this brand-new fixed abrasive technology has wide application possibilities. PMID:19209202

  9. Simulation of abrasive flow machining process for 2D and 3D mixture models

    NASA Astrophysics Data System (ADS)

    Dash, Rupalika; Maity, Kalipada

    2015-12-01

    Improvement of surface finish and material removal has been quite a challenge in a finishing operation such as abrasive flow machining (AFM). Factors that affect the surface finish and material removal are media viscosity, extrusion pressure, piston velocity, and particle size in abrasive flow machining process. Performing experiments for all the parameters and accurately obtaining an optimized parameter in a short time are difficult to accomplish because the operation requires a precise finish. Computational fluid dynamics (CFD) simulation was employed to accurately determine optimum parameters. In the current work, a 2D model was designed, and the flow analysis, force calculation, and material removal prediction were performed and compared with the available experimental data. Another 3D model for a swaging die finishing using AFM was simulated at different viscosities of the media to study the effects on the controlling parameters. A CFD simulation was performed by using commercially available ANSYS FLUENT. Two phases were considered for the flow analysis, and multiphase mixture model was taken into account. The fluid was considered to be a

  10. Study of abrasive wear rate of silicon using n-alcohols

    NASA Technical Reports Server (NTRS)

    Danyluk, S.

    1982-01-01

    The work carried out at the University of Illinois at Chicago for the Flat-Plate Solar Array Project under contract No. 956053 is summarized. The abrasion wear rate of silicon in a number of fluid environments and the parameters that influence the surface mechanical properties of silicon were determined. Three tests were carried out in this study: circular and linear multiple-scratch test, microhardness test and a three-point bend test. The pertinent parameters such as effect of surface orientation, dopant and fluid properties were sorted. A brief review and critique of previous work is presented.

  11. The effect of hydrogen peroxide on polishing removal rate in CMP with various abrasives

    NASA Astrophysics Data System (ADS)

    Manivannan, R.; Ramanathan, S.

    2009-01-01

    The effect of hydrogen peroxide in chemical mechanical planarization slurries for shallow trench isolation was investigated. The various abrasives used in this study were ceria, silica, alumina, zirconia, titania, silicon carbide, and silicon nitride. Hydrogen peroxide suppresses the polishing of silicon dioxide and silicon nitride surfaces by ceria abrasives. The polishing performances of other abrasives were either unaffected or enhanced slightly with the addition of hydrogen peroxide. The ceria abrasives were treated with hydrogen peroxide, and the polishing of the work surfaces with the treated abrasive shows that the inhibiting action of hydrogen peroxide is reversible. It was found that the effect of hydrogen peroxide as an additive is a strong function of the nature of the abrasive particle.

  12. Air Abrasion

    MedlinePlus

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  13. Lithologic Influence and Experimental Variability in Gravel Abrasion: Implications for Predicting Rates of Downstream Fining of River Bed Sediments

    NASA Astrophysics Data System (ADS)

    Farrow, J. W.; Sklar, L. S.

    2004-12-01

    The question of what controls the occurrence and rate of downstream fining of bed-material sediments remains a fundamental unsolved problem despite over a century of field, experimental and theoretical investigations. Downstream fining rates are commonly modeled as exponential or power-law functions of travel distance. Much recent work has focused on the relative influence of particle abrasion and differential transport, however, no general method has been developed for explicitly accounting for the influence of rock strength in parameterizing fining models. Here we report preliminary results of laboratory tumbling experiments in which we are investigating the influence of variable rock durability, both between and within distinct lithologic units, on rates of particle abrasion. We consider three separate questions: 1) can rock tensile strength be used to predict differences in bulk fining rates across a wide spectrum of rock types; 2) does variability in rock durability among individual gravel clasts of the same lithologic composition and initial grain size lead to patterns of downstream evolution of grain size distributions that differ significantly from the predictions of simple fining models; and 3) how large is the uncertainty in abrasion coefficients determined by laboratory tumbling, as determined by replicate experiments with identical initial conditions? We use a horizontal axis, 25-cm diameter, steel barrel tumbler, driven by a mechanical transmission with excellent control of rotational velocity. Rock samples were collected from units of the Franciscan Formation in the Redwood Creek Watershed of Marin County, California, and from sedimentary and intrusive volcanic rocks of the Henry Mountains, in southeastern Utah. We collected clasts predominantly from hillslope source areas, to focus our attention on the durability of gravel as it enters the river network. We use the `Brazilian' tensile splitting test to measure the strength of 50-mm diameter core

  14. Effect of cuticular abrasion and recovery on water loss rates in queens of the desert harvester ant Messor pergandei.

    PubMed

    Johnson, Robert A; Kaiser, Alexander; Quinlan, Michael; Sharp, William

    2011-10-15

    Factors that affect water loss rates (WLRs) are poorly known for organisms in natural habitats. Seed-harvester ant queens provide an ideal system for examining such factors because WLRs for mated queens excavated from their incipient nests are twofold to threefold higher than those of alate queens. Indirect data suggest that this increase results from soil particles abrading the cuticle during nest excavation. This study provides direct support for the cuticle abrasion hypothesis by measuring total mass-specific WLRs, cuticular abrasion, cuticular transpiration, respiratory water loss and metabolic rate for queens of the ant Messor pergandei at three stages: unmated alate queens, newly mated dealate queens (undug foundresses) and mated queens excavated from their incipient nest (dug foundresses); in addition we examined these processes in artificially abraded alate queens. Alate queens had low WLRs and low levels of cuticle abrasion, whereas dug foundresses had high WLRs and high levels of cuticle abrasion. Total WLR and cuticular transpiration were lowest for alate queens, intermediate for undug foundresses and highest for dug foundresses. Respiratory water loss contributed ~10% of the total WLR and was lower for alate queens and undug foundresses than for dug foundresses. Metabolic rate did not vary across stages. Total WLR and cuticular transpiration of artificially abraded alate queens increased, whereas respiratory water loss and metabolic rate were unaffected. Overall, increased cuticular transpiration accounted for essentially all the increased total water loss in undug and dug foundresses and artificially abraded queens. Artificially abraded queens and dug foundresses showed partial recovery after 14 days. PMID:21957113

  15. Investigation of Noise Level and Penetration Rate of Pneumatic Drill vis-à-vis Rock Compressive Strength and Abrasivity

    NASA Astrophysics Data System (ADS)

    Kivade, S. B.; Murthy, Ch. S. N.; Vardhan, H.

    2014-10-01

    In this paper, detailed studies were carried out to determine the influence of rock properties on the sound level produced during pneumatic drilling. Further, investigation was also carried out on the effect of thrust, air pressure and compressive strength on penetration rate and the sound level produced. For this purpose, a fabricated pneumatic drill set up available in the institute was used. Rock properties, like compressive strength and abrasivity, of various samples collected from the field were determined in the laboratory. Drilling experiments were carried out on ten different rock samples for varying thrust and air pressure values and the corresponding A-weighted equivalent continuous sound levels were measured. It was observed that, very low thrust results in low penetration rate. Even very high thrust does not produce high penetration rate at higher operating air pressures. With increase in thrust beyond the optimum level, the penetration rate starts decreasing and causes the drill bit to `stall'. Results of the study show that penetration rate and sound level increases with increase in the thrust level. After reaching the maximum, they start decreasing despite the increase of thrust. The main purpose of the study is to develop a general prediction model and to investigate the relationships between sound level produced during drilling and physical properties such as uniaxial compressive strength and abrasivity of sedimentary rocks. The results were evaluated using the multiple regression analysis taking into account the interaction effects of predictor variables.

  16. Dual-Flow-Rate Valve

    NASA Technical Reports Server (NTRS)

    Allbritain, R. H.

    1986-01-01

    Flow-control device precisely adjusted for two rates. Heart of twoposition valve is sliding poppet. At far-right position, poppet allows low flow. At far-left position, allows high flow. Valve supplies high-pressure gas at either of two preselected flow rates. Valve adjustable between 0.12 and 1.2 lb/s (0.054 and 0.54 kg/s) of hydrogen at 3,300 lb/in.2 (23 MN/m2) and 80 degrees F (27 degrees C). Two flow rates preadjusted between these limits in increments of 0.01 lb/s (0.0045 kg/s).

  17. The effects of abrasives on electrical submersible pumps

    SciTech Connect

    Wilson, B.L. )

    1990-06-01

    The electrical submersible pump (ESP) is a high-speed rotating device. Its operational life in oil wells can depend on the type and quantities of abrasives present in the produced fluid. This paper reports on a set of experiments performed in a specialized abrasive test loop. In the test, the size and quantity of abrasives were varied along with flow rate through the pump. This paper also examines recent literature on sand production and explores some of the practical problems in sand measurement.

  18. Valve for abrasive material

    DOEpatents

    Gardner, Harold S.

    1982-01-01

    A ball valve assembly for controlling the flow of abrasive particulates including an enlarged section at the bore inlet and an enlarged section at the bore outlet. A refractory ceramic annular deflector is positioned in each of the enlarged sections, substantially extending the useful life of the valve.

  19. Columbus Payloads Flow Rate Anomalies

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  20. Abrasion of restorative materials by toothaste.

    PubMed

    Heath, J R; Wilson, H J

    1976-04-01

    The procedure developed in this investigation is suitable for determining the abrasion resistance of restorative materials to toothbrush/dentifrice abrasion. Ideally, a restoration should have an abrasion resistance similar to that of enamel. Of the materials tested, gold was the only one that wore slightly less than enamel, whilst amalgam wore almost twice as quickly. The silicate material and composites (excluding TD.71) wear away 2-4 times faster than enamel. TD.71 and especially the unfilled resin exhibited very high rates of abrasion. After prolonged toothbrush/dentifrice abrasion, the surfaces of gold and amalgam were considerably smoother than those of the silicate and composite materials. PMID:1066445

  1. Effect of Experimental Variables of Abrasive Wear on 3D Surface Roughness and Wear Rate of Al-4.5 % Cu Alloy

    NASA Astrophysics Data System (ADS)

    Ghosh, Debashis; Mallik, Manab; Mandal, Nilrudra; Dutta, Samik; Roy, Himadri; Lohar, Aditya Kumar

    2016-05-01

    This investigation was primarily carried out to examine the abrasive wear behavior of as cast Al-4.5 % Cu alloy. Wear tests have been carried out using an abrasive wear machine with emery paper embedded with SiC particles acting as abrasive medium. The experiments were planned using central composite design, with, load, cycle and grit size as input variables, whereas wear rate and 3D roughness were considered as output variable. Analysis of variance was applied to check the adequacy of the mathematical model and their respective parameters. Microstructural investigations of the worn surfaces have been carried out to explain the observed results and to understand the wear micro-mechanisms as per the planned experiments. Desirability function optimization technique was finally employed to optimize the controlling factors. The observed results revealed that, grit size plays a significant role in the variation of wear rate and 3D roughness as compared to load and cycles. Based on the significance of interactions, the regression equations were derived and verified further with a number of confirmation runs to assess the adequacy of the model. A close agreement (±10 %) between the predicted and experimentally measured results was obtained from this investigation.

  2. Abrasion of heavy-duty coated steel pipes by sediment transport

    SciTech Connect

    Kariyazono, Yoshihisa; Miyajima, Yoshihiro; Sato, Koichi; Yamashita, Toshihiko, Yamashita; Saeki, Hiroshi

    1994-12-31

    Heavy-duty coatings are standard treatment for steel pipe piles in coastal zones to prevent corrosion. Large amounts of sand sometimes drift around piles by the action of waves. Coatings undergo abrasion by collision of sand particles. Authors carried out experiments by a large scale U-shaped tube which generated a strong oscillatory flow with sand drift and numerical analysis of collision of the particles. Authors found out the abrasion rate of pile is nearly proportional to the collision energy of the particles. Abrasion rate of polyethylene and elastic polyurethane coatings were lower than those of other materials.

  3. Flow rate measuring devices for gas flows

    NASA Astrophysics Data System (ADS)

    Bonfig, K. W.

    1985-07-01

    Flowrate measuring devices are described: volume meter with fixed or mobile walls; turbine meter; throttling procedure; ultrasonic and Doppler methods; vortex method; rotary flowmeter; and swinging body flow measuring procedure. Flowrate can also be measured from the force exerted on bodies immersed in a fluid or based on thermodynamical principles. The characteristics and operating envelope of each device/method are given.

  4. Flow rate logging seepage meter

    NASA Technical Reports Server (NTRS)

    Reay, William G. (Inventor); Walthall, Harry G. (Inventor)

    1996-01-01

    An apparatus for remotely measuring and logging the flow rate of groundwater seepage into surface water bodies. As groundwater seeps into a cavity created by a bottomless housing, it displaces water through an inlet and into a waterproof sealed upper compartment, at which point, the water is collected by a collection bag, which is contained in a bag chamber. A magnet on the collection bag approaches a proximity switch as the collection bag fills, and eventually enables the proximity switch to activate a control circuit. The control circuit then rotates a three-way valve from the collection path to a discharge path, enables a data logger to record the time, and enables a pump, which discharges the water from the collection bag, through the three-way valve and pump, and into the sea. As the collection bag empties, the magnet leaves the proximity of the proximity switch, and the control circuit turns off the pump, resets the valve to provide a collection path, and restarts the collection cycle.

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

    DOEpatents

    Robertson, Eric P.

    2006-08-01

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

  6. Measuring Your Peak Flow Rate

    MedlinePlus

    ... meter. Proper cleaning with mild detergent in hot water will keep your peak flow meter working accurately and may keep you healthier. Related Content News: American Lung Association Applauds EPA’s Update to Cross-State Air Pollution Rule News: American Lung Association Invests More Than $ ...

  7. Dust transport and abrasion assessment within simulated standing vegetation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop residues are useful in protecting the top soil from depletion and abrasion due to wind erosion. A wind tunnel study was done to measure sand transport and abrasion energies within the simulated artificial standing vegetation. Wind profiles, relative abrasion energies and rates of sand dischar...

  8. Relationship between abrasive wear and microstructure of composite resins.

    PubMed

    Draughn, R A; Harrison, A

    1978-08-01

    The in vitro abrasion resistance of seven commercial composite resin restorative materials has been measured. Analysis of the composite microstructures shows that abrasion rates are dependent upon the size, hardness, and volume fraction of particles in the material. The most abrasion-resistant composites contain a high volume fraction of large, hard particles. PMID:278840

  9. CFD Based Erosion Modelling of Abrasive Waterjet Nozzle using Discrete Phase Method

    NASA Astrophysics Data System (ADS)

    Hakim Kamarudin, Naqib; Prasada Rao, A. K.; Azhari, Azmir

    2016-02-01

    In Abrasive Waterjet (AWJ) machining, the nozzle is the most critical component that influences the performance, precision and economy. Exposure to a high speed jet and abrasives makes it susceptible to wear erosion which requires for frequent replacement. The present works attempts to simulate the erosion of the nozzle wall using computational fluid dynamics. The erosion rate of the nozzle was simulated under different operating conditions. The simulation was carried out in several steps which is flow modelling, particle tracking and erosion rate calculation. Discrete Phase Method (DPM) and K-ε turbulence model was used for the simulation. Result shows that different operating conditions affect the erosion rate as well as the flow interaction of water, air and abrasives. The simulation results correlates well with past work.

  10. Flow Rate Measurements Using Flow-Induced Pipe Vibration

    SciTech Connect

    R. P. Evans; Jonathan D. Blotter; Alan G. Stephens

    2004-03-01

    This paper focuses on the possibility of a non-intrusive, low cost, flow rate measurement technique. The technique is based on signal noise from an accelerometer attached to the surface of the pipe. The signal noise is defined as the standard deviation of the frequency averaged time series signal. Experimental results are presented that indicate a nearly quadratic relationship between the signal noise and mass flow rate in the pipe. It is also shown that the signal noise - flow rate relationship is dependant on the pipe material and diameter.

  11. Flow rate limitation in open capillary channel flows.

    PubMed

    Haake, Dennis; Rosendahl, Uwe; Ohlhoff, Antje; Dreyer, Michael E

    2006-09-01

    This paper reports the experimental and theoretical investigations of forced liquid flows through open capillary channels under reduced gravity conditions. An open capillary channel is a structure that establishes a liquid flow path at low Bond numbers, when the capillary pressure caused by the surface tension force dominates in comparison to the hydrostatic pressure induced by gravitational or residual accelerations. In case of steady flow through the channel, the capillary pressure of the free surface balances the pressure difference between the liquid and the surrounding constant-pressure gas phase. Because of convective and viscous momentum transport, the pressure along the flow path decreases and causes the free surface to bend inward. The maximum flow rate is achieved when the free surface collapses and gas ingestion occurs at the outlet. This critical flow rate depends on the geometry of the channel and the properties of the liquid. In this paper we present a comparison of the theoretical and experimental critical flow rates and surface profiles for convective dominated flows. For the prediction of the critical flow rate a one-dimensional theoretical model taking into account the entrance pressure loss and the frictional pressure loss in the channel is developed. PMID:17124140

  12. Historical river flow rates for dose calculations

    SciTech Connect

    Carlton, W.H.

    1991-06-10

    Annual average river flow rates are required input to the LADTAP Computer Code for calculating offsite doses from liquid releases of radioactive materials to the Savannah River. The source of information on annual river flow rates used in dose calculations varies, depending on whether calculations are for retrospective releases or prospective releases. Examples of these types of releases are: Retrospective - releases from routine operations (annual environmental reports) and short term release incidents that have occurred. Prospective - releases that might be expected in the future from routine or abnormal operation of existing or new facilities (EIS`s, EID`S, SAR`S, etc.). This memorandum provides historical flow rates at the downstream gauging station at Highway 301 for use in retrospective dose calculations and derives flow rate data for the Beaufort-Jasper and Port Wentworth water treatment plants.

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  14. Abrasion resistance of linings in filament wound composite pipe

    SciTech Connect

    Hall, S.C.

    1999-07-01

    Fiberglass filament wound composite pipe has numerous industrial applications including transportation of petroleum and natural gas. Its corrosion resistance is well known but it can be susceptible to abrasion and erosion when it is used to transport slurries or dry gas containing sand particles. However, composite pipe can be manufactured integrally with abrasion resistant linings which protect the pipe from abrasion and erosion and increase its life. Laboratory investigations were performed to determine the effect of abrasive flows through polyurea-lined and unlined glass-reinforced epoxy (GRE) pipe, ultra-high molecular weight (UHMW) polyethylene (PE) pipe, and unlined steel pipe. Results are provided for the abrasion resistance, chemical resistance, adhesion strength, elongation, tensile strength, impact resistance and hardness of selected linings. The abrasion resistance of polyurea-lined composite pipe proved to be almost as resistant to abrasion and erosion as unlined steel pipe without the electrochemical corrosion associated with steel pipe.

  15. Ultrasonic rate measurement of multiphase flow

    SciTech Connect

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

    1993-01-01

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

  16. Ultrasonic rate measurement of multiphase flow

    NASA Astrophysics Data System (ADS)

    Dannert, David A.; Horne, Roland N.

    1993-01-01

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

  17. Measurements of the Coefficient of Restitution of Quartz Sand on Basalt: Implications for Abrasion Rates on Earth and Mars

    NASA Technical Reports Server (NTRS)

    Banks, M.; Bridges, N. T.; Benzit, M.

    2005-01-01

    Knowledge of the rates at which rocks abrade from the impact of saltating sand provides important input into estimating the age and degree of modification of arid surfaces on Earth and Mars. Previous work has relied on measuring mass loss rates in the field and the laboratory. The susceptibility of rocks and other natural materials has been quantified on a relative scale from laboratory studies.

  18. Abrasion by aeolian particles: Earth and Mars

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Marshall, J. R.; White, B. R.; Pollack, J. B.; Marshall, J.; Krinsley, D.

    1984-01-01

    Estimation of the rate of aeolian abrasion of rocks on Mars requires knowledge of: (1) particle flux, (2) susceptibilities to abrasion of various rocks, and (3) wind frequencies on Mars. Fluxes and susceptibilities for a wide range of conditions were obtained in the laboratory and combined with wind data from the Viking meteorology experiment. Assuming an abundant supply of sand-sized particles, estimated rates range up to 2.1 x 10 to the minus 2 power cm of abrasion per year in the vicinity of Viking Lander 1. This rate is orders of magnitude too great to be in agreement with the inferred age of the surface based on models of impact crater flux. The discrepancy in the estimated rate of abrasion and the presumed old age of the surface cannot be explained easily by changes in climate or exhumation of ancient surfaces. The primary reason is thought to be related to the agents of abrasion. At least some sand-sized (approx. 100 micrometers) grains appear to be present, as inferred from both lander and orbiter observations. High rates of abrasion occur for all experimental cases involving sands of quartz, basalt, or ash. However, previous studies have shown that sand is quickly comminuted to silt- and clay-sized grains in the martian aeolian regime. Experiments also show that these fine grains are electrostatically charged and bond together as sand-sized aggregates. Laboratory simulations of wind abrasion involving aggregates show that at impact velocities capable of destroying sand, aggregates from a protective veneer on the target surface and can give rise to extremely low abrasion rates.

  19. Electromagnetic flow rate meter. [for liquid metals

    NASA Technical Reports Server (NTRS)

    Banks, B. A. (Inventor)

    1974-01-01

    A liquid metal, whose flow rate is to be determined, is directed through a chamber made of electrically-insulating material on which there is impressed a magnetic field perpendicular to the direction of flow of the liquid metal. The magnetic field is made to increase in strength in a downstream direction of the flow of liquid metal. At least a pair of electrodes are disposed in the chamber traversely and perpendicular to the direction of flow and an ammeter is connected between the electrodes. Electrodes may be disposed in the top or the bottom of the chamber and each may be segmented. Oppositely disposed electrodes may be used with at least one dividing wall extending from each electrode to cause reversal of the direction of flow of the liquid metal. The magnetic field may be provided by electromagnets or permanent magnets such as shaded pole permanent magnets.

  20. Reserve, flowing electrolyte, high rate lithium battery

    NASA Astrophysics Data System (ADS)

    Puskar, M.; Harris, P.

    Flowing electrolyte Li/SOCl2 tests in single cell and multicell bipolar fixtures have been conducted, and measurements are presented for electrolyte flow rates, inlet and outlet temperatures, fixture temperatures at several points, and the pressure drop across the fixture. Reserve lithium batteries with flowing thionyl-chloride electrolytes are found to be capable of very high energy densities with usable voltages and capacities at current densities as high as 500 mA/sq cm. At this current density, a battery stack 10 inches in diameter is shown to produce over 60 kW of power while maintaining a safe operating temperature.

  1. Controlling a wide range of flow rates

    NASA Technical Reports Server (NTRS)

    Perkins, G. S.

    1979-01-01

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

  2. Rates of Flow: Some Useful Equations.

    ERIC Educational Resources Information Center

    Robertson, I. S.

    1979-01-01

    Presents a step-by-step approach to be used in solving different forms of physics problems, starting from familiar grounds and finding well known results on the way. Uses the rate of heat flow and the resulting changes of temperature with time of a copper block as an example. (GA)

  3. [The application of air abrasion in dentistry].

    PubMed

    Mandinić, Zoran; Vulićević, Zoran R; Beloica, Milos; Radović, Ivana; Mandić, Jelena; Carević, Momir; Tekić, Jasmina

    2014-01-01

    One of the main objectives of contemporary dentistry is to preserve healthy tooth structure by applying techniques of noninvasive treatment. Air abrasion is a minimally invasive nonmechanical technique of tooth preparation that uses kinetic energy to remove carious tooth structure. A powerful narrow stream of moving aluminum-oxide particles hit the tooth surface and they abrade it without heat, vibration or noise. Variables that affect speed of cutting include air pressure, particle size, powder flow, tip's size, angle and distance from the tooth. It has been proposed that air abrasion can be used to diagnose early occlusal-surface lesions and treat them with minimal tooth preparation using magnifier. Reported advantages of air abrasion include reduced noise, vibration and sensitivity. Air abrasion cavity preparations have more rounded internal contours than those prepared with straight burs. This may increase the longevity of placed restorations because it reduces the incidence of fractures and a consequence of decreased internal stresses. However, air abrasion cannot be used for all patients, i.e. in cases involving severe dust allergy, asthma, chronic obstructive lung disease, recent extraction or other oral surgery, open wounds, advanced periodontal disease, recent placement of orthodontic appliances and oral abrasions, or subgingival caries removal. Many of these conditions increase the risk of air embolism in the oral soft tissues. Dust control is a challenge, and it necessitates the use of rubber dam, high-volume evacuation, protective masks and safety eyewear for both the patient and the therapist. PMID:24684041

  4. Flow rate measurement in aggressive conductive fluids

    NASA Astrophysics Data System (ADS)

    Dubovikova, Nataliia; Kolesnikov, Yuri; Karcher, Christian

    2014-03-01

    Two non-contact experimental methods of flow rate measurements for aggressive conductive liquids are described. The techniques are based on electromagnetic forces and Faraday's law: Lorentz force is induced inside moving conductive liquid under influence of variable magnetic field of permanent magnets. They are mounted along a liquid metal channel or (in case of the second method) inserted into rotated metal wheels. The force acts in the opposite of fluids' velocity direction and hence it is possible to measure reaction force of it that takes place according to Newton's law on magnetic field source - permanent magnets. And by knowing the force, which linearly depends on velocity, one can calculate mean flow rate of liquid. In addition experimental "dry" calibration and its results are described for one of the measurements' techniques.

  5. Microwave sintering of sol-gel derived abrasive grain

    DOEpatents

    Plovnick, Ross; Celikkaya, Ahmet; Blake, Rodger D.

    1997-01-01

    A method is provided for making microwave-sintered, free flowing alpha alumina-based ceramic abrasive grain, under conditions effective to couple microwaves with calcined alpha alumina-based abrasive gain precursor and sinter it at a temperature of at least about 1150.degree. C.

  6. Electromechanically Actuated Valve for Controlling Flow Rate

    NASA Technical Reports Server (NTRS)

    Patterson, Paul

    2007-01-01

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

  7. Deconvolution of wellbore pressure and flow rate

    SciTech Connect

    Kuchuk, F.J. ); Carter, R.G. . Langley Research Center); Ayestaran, L. )

    1990-03-01

    Determination of the influence function of a well/reservoir system from the deconvolution of wellbore flow rate and pressure is presented. Deconvolution is fundamental and is particularly applicable to system identification. A variety of different deconvolution algorithms are presented. The simplest algorithm is a direct method that works well for data without measurement noise but that fails in the presence of even small amounts of noise. The authors show, however, that a modified algorithm that imposes constraints on the solution set works well, even with significant measurement errors.

  8. Bio-active glass air-abrasion has the potential to remove resin composite restorative material selectively

    NASA Astrophysics Data System (ADS)

    Milly, Hussam; Andiappan, Manoharan; Thompson, Ian; Banerjee, Avijit

    2014-06-01

    The aims of this study were to assess: (a) the chemistry, morphology and bioactivity of bio-active glass (BAG) air-abrasive powder, (b) the effect of three air-abrasion operating parameters: air pressure, powder flow rate (PFR) and the abrasive powder itself, on the selective removal of resin composite and (c) the required “time taken”. BAG abrasive particles were characterised using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and Fourier-transform infrared spectroscopy (FTIR). Standardised resin composite restorations created within an enamel analogue block (Macor™) in vitro, were removed using air-abrasion undersimulated clinical conditions. 90 standardised cavities were scanned before and after resin composite removal using laser profilometry and the volume of the resulting 3D images calculated. Multilevel linear model was used to identify the significant factors affecting Macor™ removal. BAG powder removed resin composite more selectively than conventional air-abrasion alumina powder using the same operating parameters (p < 0.001) and the effect of altering the unit's operating parameters was significant (p < 0.001). In conclusion, BAG powder is more efficient than alumina in the selective removal of resin composite particularly under specific operating parameters, and therefore may be recommended clinically as a method of preserving sound enamel structure when repairing and removing defective resin composite restorations.

  9. Solids flow rate measurement in dense slurries

    SciTech Connect

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

    1993-09-01

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

  10. A review on nozzle wear in abrasive water jet machining application

    NASA Astrophysics Data System (ADS)

    Syazwani, H.; Mebrahitom, G.; Azmir, A.

    2016-02-01

    This paper discusses a review on nozzle wear in abrasive water jet machining application. Wear of the nozzle becomes a major problem since it may affect the water jet machining performance. Design, materials, and life of the nozzle give significance effect to the nozzle wear. There are various parameters that may influence the wear rate of the nozzle such as nozzle length, nozzle inlet angle, nozzle diameter, orifice diameter, abrasive flow rate and water pressure. The wear rate of the nozzle can be minimized by controlling these parameters. The mechanism of wear in the nozzle is similar to other traditional machining processes which uses a cutting tool. The high pressure of the water and hard abrasive particles may erode the nozzle wall. A new nozzle using a tungsten carbide-based material has been developed to reduce the wear rate and improve the nozzle life. Apart from that, prevention of the nozzle wear has been achieved using porous lubricated nozzle. This paper presents a comprehensive review about the wear of abrasive water jet nozzle.

  11. Machining human dentin by abrasive water jet drilling.

    PubMed

    Kohorst, Philipp; Tegtmeyer, Sven; Biskup, Christian; Bach, Friedrich-Wilhelm; Stiesch, Meike

    2014-01-01

    The aim of this experimental in-vitro study was to investigate the machining of human dentin using an abrasive water jet and to evaluate the influence of different abrasives and water pressures on the removal rate. Seventy-two human teeth had been collected after extraction and randomly divided into six homogeneous groups (n=12). The teeth were processed in the area of root dentin with an industrial water jet device. Different abrasives (saccharose, sorbitol, xylitol) and water pressures (15 or 25 MPa) were used in each group. Dimensions of dentin removal were analysed using a stripe projection microscope and both drilling depth as well as volume of abrasion were recorded. Morphological analyses of the dentin cavities were performed using scanning electron microscopy (SEM). Both drilling depth and volume of abrasion were significantly influenced by the abrasive and the water pressure. Depending on these parameters, the drilling depth averaged between 142 and 378 μm; the volume of abrasion averaged between 0.07 and 0.15 mm3. Microscopic images revealed that all cavities are spherical and with clearly defined margins. Slight differences between the abrasives were found with respect to the microroughness of the surface of the cavities. The results indicate that abrasive water jet machining is a promising technique for processing human dentin. PMID:24642975

  12. Adjustable flow rate controller for polymer solutions

    DOEpatents

    Jackson, Kenneth M.

    1981-01-01

    An adjustable device for controlling the flow rate of polymer solutions which results in only little shearing of the polymer molecules, said device comprising an inlet manifold, an outlet manifold, a plurality of tubes capable of providing communication between said inlet and outlet manifolds, said tubes each having an internal diameter that is smaller than that of the inlet manifold and large enough to insure that viscosity of the polymer solution passing through each said tube will not be reduced more than about 25 percent, and a valve associated with each tube, said valve being capable of opening or closing communication in that tube between the inlet and outlet manifolds, each said valve when fully open having a diameter that is substantially at least as great as that of the tube with which it is associated.

  13. Universal scaling relations for pebble abrasion

    NASA Astrophysics Data System (ADS)

    Litwin, K. L.; Jerolmack, D. J.

    2012-12-01

    The process of abrasion of gravel in bed load transport results from particle-to-particle collisions, where the energy involved is sufficient to cause chipping and spallation but not fragmentation of parent grains. The removed rock material is not infinitesimal; daughter products as large as coarse sand can be produced. Although previous work has shown that lithology, grain shape, and energy of collision are contributing factors that control abrasion rates of river-bed material, little is known regarding the relationship between these factors and diminution rates. Here we explicitly isolate and investigate how these three factors influence rates of abrasion and the size distribution of daughter products, with laboratory experiments. The apparatus is a double pendulum (Newton's cradle) that produces well-controlled binary collisions. A high-speed camera precisely measures collision energy, while mass of parent rocks. and the size and shape distributions of daughter products, are measured periodically. We examined abrasion of initially square-cut 'rocks' as they underwent successive collisions in the binary collision apparatus. We have examined mass loss rate for varied lithologies, and observe a similar power-law relationship between impact energy and mass abraded. When normalized by sensible material properties, mass loss curves for all materials collapse onto a single curve, suggesting that the underlying mechanics of abrasion for different materials are the same. The relationship does not display the linear trend expected from pure energetics, and we suggest that this is a shape effect as protruding - and hence easily eroded - corners are worn away. Analysis of daughter-product particle size distributions for different lithology fragments - including natural rocks and also bricks - show the same functional form. Surprisingly, it is the power-law relation expected for brittle materials undergoing fragmentation. This suggests that brittle fracture theory also

  14. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... spindle speed under all conditions of normal grinding. The rated maximum speed of the wheel shall not be...) Floor stand and bench mounted abrasive wheels used for external grinding shall be provided with safety guards (protection hoods). The maximum angular exposure of the grinding wheel periphery and sides...

  15. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... spindle speed under all conditions of normal grinding. The rated maximum speed of the wheel shall not be...) Floor stand and bench mounted abrasive wheels used for external grinding shall be provided with safety guards (protection hoods). The maximum angular exposure of the grinding wheel periphery and sides...

  16. Quantitative Estimation of Tissue Blood Flow Rate.

    PubMed

    Tozer, Gillian M; Prise, Vivien E; Cunningham, Vincent J

    2016-01-01

    The rate of blood flow through a tissue (F) is a critical parameter for assessing the functional efficiency of a blood vessel network following angiogenesis. This chapter aims to provide the principles behind the estimation of F, how F relates to other commonly used measures of tissue perfusion, and a practical approach for estimating F in laboratory animals, using small readily diffusible and metabolically inert radio-tracers. The methods described require relatively nonspecialized equipment. However, the analytical descriptions apply equally to complementary techniques involving more sophisticated noninvasive imaging.Two techniques are described for the quantitative estimation of F based on measuring the rate of tissue uptake following intravenous administration of radioactive iodo-antipyrine (or other suitable tracer). The Tissue Equilibration Technique is the classical approach and the Indicator Fractionation Technique, which is simpler to perform, is a practical alternative in many cases. The experimental procedures and analytical methods for both techniques are given, as well as guidelines for choosing the most appropriate method. PMID:27172960

  17. Abrasion resistant heat pipe

    DOEpatents

    Ernst, Donald M.

    1984-10-23

    A specially constructed heat pipe for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

  18. Abrasion resistant heat pipe

    DOEpatents

    Ernst, D.M.

    1984-10-23

    A specially constructed heat pipe is described for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

  19. 46 CFR 162.018-7 - Flow rating tests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Flow rating tests. 162.018-7 Section 162.018-7 Shipping...: SPECIFICATIONS AND APPROVAL ENGINEERING EQUIPMENT Safety Relief Valves, Liquefied Compressed Gas § 162.018-7 Flow rating tests. (a) Flow rating of valves shall be conducted in accordance with UG-131 of section VIII...

  20. 14 CFR 23.1095 - Carburetor deicing fluid flow rate.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Carburetor deicing fluid flow rate. 23.1095... Induction System § 23.1095 Carburetor deicing fluid flow rate. (a) If a carburetor deicing fluid system is used, it must be able to simultaneously supply each engine with a rate of fluid flow, expressed...

  1. 14 CFR 23.1095 - Carburetor deicing fluid flow rate.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Carburetor deicing fluid flow rate. 23.1095... Induction System § 23.1095 Carburetor deicing fluid flow rate. (a) If a carburetor deicing fluid system is used, it must be able to simultaneously supply each engine with a rate of fluid flow, expressed...

  2. 14 CFR 23.1095 - Carburetor deicing fluid flow rate.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Carburetor deicing fluid flow rate. 23.1095... Induction System § 23.1095 Carburetor deicing fluid flow rate. (a) If a carburetor deicing fluid system is used, it must be able to simultaneously supply each engine with a rate of fluid flow, expressed...

  3. 14 CFR 23.1095 - Carburetor deicing fluid flow rate.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Carburetor deicing fluid flow rate. 23.1095... Induction System § 23.1095 Carburetor deicing fluid flow rate. (a) If a carburetor deicing fluid system is used, it must be able to simultaneously supply each engine with a rate of fluid flow, expressed...

  4. 14 CFR 23.1095 - Carburetor deicing fluid flow rate.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Carburetor deicing fluid flow rate. 23.1095... Induction System § 23.1095 Carburetor deicing fluid flow rate. (a) If a carburetor deicing fluid system is used, it must be able to simultaneously supply each engine with a rate of fluid flow, expressed...

  5. Abrasion protection in process piping

    SciTech Connect

    Accetta, J.

    1996-07-01

    Process piping often is subjected to failure from abrasion or a combination of abrasion and corrosion. Abrasion is a complex phenomenon, with many factors involved to varying degrees. Hard, mineral based alumina ceramic and basalt materials are used to provide protection against abrasion in many piping systems. Successful life extension examples are presented from many different industries. Lined piping components require special attention with regard to operating conditions as well as design and engineering considerations. Economic justification involves direct cost comparisons and avoided costs.

  6. Nutrient transport as affected by rate of overland flow

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little information is currently available concerning the effects of varying flow rate on nutrient transport by overland flow. The objective of this study was to measure the effects of overland flow rate on nutrient transport following the application of beef cattle or swine manure to plots containin...

  7. Abrasion resistant composition

    DOEpatents

    Fischer, Keith D; Barnes, Christopher A; Henderson, Stephen L

    2014-05-13

    A surface covering composition of abrasion resistant character adapted for disposition in overlying bonded relation to a metal substrate. The surface covering composition includes metal carbide particles within a metal matrix at a packing factor of not less than about 0.6. Not less than about 40 percent by weight of the metal carbide particles are characterized by an effective diameter in the range of +14-32 mesh prior to introduction to the metal matrix. Not less than about 3 percent by weight of the metal carbide particles are characterized by an effective diameter of +60 mesh prior to introduction to the metal matrix.

  8. Ionospheric Heating Rates Associated with Solar Wind Forcing: Ejecta flow, High Speed Flow and Slow Flow

    NASA Astrophysics Data System (ADS)

    Knipp, D. J.; Kasprzak, B.; Richardson, I.; Paige, T.; Evans, D.

    2001-12-01

    We present estimates of global ionospheric Joule and particle heating as a function of solar wind flow types over solar cycles 21, 22 and the first half of solar cycle 23. Richardson et al., [JGR, 2000] used a variety of techniques to categorize the solar wind flow as ejecta, high-speed stream or slow flow. Their work provides the basis for our catigorization of heating by flow type. The estimates of Joule heating are based on output of the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure, and fits to the Polar Cap Index [Chun et al., GRL, 1999]. Estimates of particle heating are derived from polar orbiting satellites. Although ejecta only account for 19% of the solar wind flow, they account for 27% of the Joule heating. High-speed stream flow accounts for 47% of the flow occurrence and 44% of the Joule heating. We will show similar comparisons for particle heating. Our solar cycle statistics indicate that Joule heating produces a yearly average hemispheric heating rate of 53 GW while particles produce a hemispheric heating rate of 38 GW. Joule heating exhibits more variability than particle heating. During solar cycle maximum years Joule heating accounts for twice the heating associated with particles heating.

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

    NASA Technical Reports Server (NTRS)

    Branum, L. W.

    1966-01-01

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

  10. Kerf modelling in abrasive waterjet milling using evolutionary computation and ANOVA techniques

    NASA Astrophysics Data System (ADS)

    Alberdi, A.; Rivero, A.; Carrascal, A.; Lamikiz, A.

    2012-04-01

    Many researchers demonstrated the capability of Abrasive Waterjet (AWJ) technology for precision milling operations. However, the concurrence of several input parameters along with the stochastic nature of this technology leads to a complex process control, which requires a work focused in process modelling. This research work introduces a model to predict the kerf shape in AWJ slot milling in Aluminium 7075-T651 in terms of four important process parameters: the pressure, the abrasive flow rate, the stand-off distance and the traverse feed rate. A hybrid evolutionary approach was employed for kerf shape modelling. This technique allowed characterizing the profile through two parameters: the maximum cutting depth and the full width at half maximum. On the other hand, based on ANOVA and regression techniques, these two parameters were also modelled as a function of process parameters. Combination of both models resulted in an adequate strategy to predict the kerf shape for different machining conditions.

  11. Effect of abrasive grit size on wear of manganese-zinc ferrite under three-body abrasion

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1987-01-01

    Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and deformed layers produced in single-crystal Mn-Zn ferrites under three-body abrasion. The abrasion mechanism of Mn-Zn ferrite changes drastically with the size of abrasive grits. With 15-micron (1000-mesh) SiC grits, abrasion of Mn-Zn ferrite is due principally to brittle fracture; while with 4- and 2-micron (4000- and 6000-mesh) SiC grits, abrasion is due to plastic deformation and fracture. Both microcracking and plastic flow produce polycrystalline states on the wear surfaces of single-crystal Mn-Zn ferrites. Coefficient of wear, total thickness of the deformed layers, and surface roughness of the wear surfaces increase markedly with an increase in abrasive grit size. The total thicknesses of the deformed layers are 3 microns for the ferrite abraded by 15-micron SiC, 0.9 microns for the ferrite abraded by 4-micron SiC, and 0.8 microns for the ferrite abraded by 1-micron SiC.

  12. In vitro effect of air-abrasion operating parameters on dynamic cutting characteristics of alumina and bio-active glass powders.

    PubMed

    Milly, H; Austin, R S; Thompson, I; Banerjee, A

    2014-01-01

    Minimally invasive dentistry advocates the maintenance of all repairable tooth structures during operative caries management in combination with remineralization strategies. This study evaluated the effect of air-abrasion operating parameters on its cutting efficiency/pattern using bio-active glass (BAG) powder and alumina powder as a control in order to develop its use as a minimally invasive operative technique. The cutting efficiency/pattern assessment on an enamel analogue, Macor, was preceded by studying the powder flow rate (PFR) of two different commercial intraoral air-abrasion units with differing powder-air admix systems. The parameters tested included air pressure, powder flow rate, nozzle-substrate distance, nozzle angle, shrouding the air stream with a curtain of water, and the chemistry of abrasive powder. The abraded troughs were scanned and analyzed using confocal white light profilometry and MountainsMap surface analysis software. Data were analyzed statistically using one-way and repeated-measures analysis of variance tests (p=0.05). The air-abrasion unit using a vibration mechanism to admix the abrasive powder with the air stream exhibited a constant PFR regardless of the set air pressure. Significant differences in cutting efficiency were observed according to the tested parameters (p<0.05). Alumina powder removed significantly more material than did BAG powder. Using low air pressure and suitable consideration of the effect of air-abrasion parameters on cutting efficiency/patterns can improve the ultraconservative cutting characteristics of BAG air-abrasion, thereby allowing an introduction of this technology for the controlled cleaning/removal of enamel, where it is indicated clinically. PMID:23718212

  13. Changes in rabbit lacrimal gland fluid osmolarity with flow rate.

    PubMed

    Gilbard, J P; Dartt, D A

    1982-12-01

    To determine whether the osmolarity of rabbit lacrimal gland fluid (LGF) changes with flow rate, microvolumes (approximately 0.2 microliters) were collected directly from he cannulated glandular excretory duct of anesthetized rabbits. Low flow rates were obtained by collection of LGF 5 min after instillation of proparacaine: higher flow rates were obtained by stimulation with 0.45, 0.9, 3.8, or 15 micrograms of acetylcholine administered by local arterial injection. At low flow rates (less than 0.11 microliters/min), LGF osmolarity was 334 +/- 4 mOsm/L (n = 19). As flow rate increased to maximal rates (13.0 to 19.1 microliters/min), LGF osmolarity decreased to a value of 299 +/- 2 mOsm/L (n = 7). In keratoconjunctivitis sicca, increase in LGF osmolarity, as well as tear film evaporation, may contribute to elevated tear film osmolarity. PMID:7141824

  14. 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.

  15. Loose abrasive slurries for optical glass lapping

    SciTech Connect

    Neauport, Jerome; Destribats, Julie; Maunier, Cedric; Ambard, Chrystel; Cormont, Philippe; Pintault, B.; Rondeau, Olivier

    2010-10-20

    Loose abrasive lapping is widely used to prepare optical glass before its final polishing. We carried out a comparison of 20 different slurries from four different vendors. Slurry particle sizes and morphologies were measured. Fused silica samples were lapped with these different slurries on a single side polishing machine and characterized in terms of surface roughness and depth of subsurface damage (SSD). Effects of load, rotation speed, and slurry concentration during lapping on roughness, material removal rate, and SSD were investigated.

  16. Flow rates through earthen, geomembrane & composite cut-off walls

    SciTech Connect

    Tachavises, C.; Benson, C.H.

    1997-12-31

    Flow rates through soil-bentonite (SIB), geomembrane (GM), and composite geomembrane-soil (CGS) cut-off walls were determined using a numerical model of ground water flow. Various geological and wall conditions were simulated. Results of the simulations show that flow rates past all wall types are affected by hydraulic conductivities of the aquifer and underlying confining layer. Flow rates past GM walls with perfect joints are very low, provided the confining layer has low hydraulic conductivity. However, if a small fraction of the joints are defective, GM walls can be ineffective in blocking flow. CGS walls with a low hydraulic conductivity shell are less sensitive to joint defects. CGS walls with good shells typically have lower flow rates than SB and GM walls, even if the CGS wall contains defective joints.

  17. Abrasive Wear Study of NiCrFeSiB Flame Sprayed Coating

    NASA Astrophysics Data System (ADS)

    Sharma, Satpal

    2013-10-01

    In the present study, abrasive wear behavior of NiCrFeSiB alloy coating on carbon steel was investigated. The NiCrFeSiB coating powder was deposited by flame spraying process. The microstructure, porosity and hardness of the coatings were evaluated. Elemental mapping was carried out in order to study the distribution of various elements in the coating. The abrasive wear behavior of these coatings was investigated under three normal loads (5, 10 and 15 N) and two abrasive grit sizes (120 and 320 grit). The abrasive wear rate was found to increase with the increase of load and abrasive size. The abrasive wear resistance of coating was found to be 2-3 times as compared to the substrate. Analysis of the scanning electron microscope images revealed cutting and plowing as the material removal mechanisms in these coatings under abrasive wear conditions used in this investigation.

  18. Mechanics, kinematics and geometry of pebble abrasion from binary collisions

    NASA Astrophysics Data System (ADS)

    Miller, K. L.; Jerolmack, D. J.

    2014-12-01

    As sediment is transported downstream as bedload, it collides with the bed causing sharp edges to chip and wear away, rounding the rock through the process of abrasion. Previous work has linked abrasion to downstream fining and rounding of grains, however, there has been little attempt to understand the underlying kinematics of abrasion. Furthermore, most studies neglect the fine particle produced during the abrasion process, as the initial grain gets smaller and rounder. In this research, we preform well-controlled laboratory experiments to determine the functional dependence between impact energy and mass lost from abrasion. We use a double-pendulum "Newton's Cradle" set-up to examine the abrasion between two grains and with a high-speed camera, we can quantify the impact energies during collision. Results from experiments verify that mass loss is proportional to kinetic energy. We define a material parameter that incorporates material density, Young's modulus, and tensile stress and show that this parameter is directly related to the proportionality between mass loss and energy. We identify an initial region of the mass loss curves in which abrasion is independent of energy and material properties; results suggest this region is determined by shape. We show that grain size distributions of daughter products are universal and independent of material; they follow a Weibull distribution, which is expected distribution from brittle fracture theory. Finally, scanning electron microscope (SEM) images show a thin damage zone near the surface, suggesting that collision energy is attenuated over some small skin depth. Overall, we find that pebble abrasion by collision can be characterized by two universal scaling relations - the mass loss versus energy curves and the size distribution of daughter products. Results will be useful for estimating expected abrasion rates in the field, and additionally demonstrate that low-energy collisions produce large quantities of sand

  19. Atmospheric particulate emissions from dry abrasive blasting using coal slag.

    PubMed

    Kura, Bhaskar; Kambham, Kalpalatha; Sangameswaran, Sivaramakrishnan; Potana, Sandhya

    2006-08-01

    Coal slag is one of the widely used abrasives in dry abrasive blasting. Atmospheric emissions from this process include particulate matter (PM) and heavy metals, such as chromium, lead, manganese, nickel. Quantities and characteristics of PM emissions depend on abrasive characteristics and process parameters. Emission factors are key inputs to estimate emissions. Experiments were conducted to study the effect of blast pressure, abrasive feed rate, and initial surface contamination on total PM (TPM) emission factors for coal slag. Rusted and painted mild steel surfaces were used as base plates. Blasting was carried out in an enclosed chamber, and PM was collected from an exhaust duct using U.S. Environment Protection Agency source sampling methods for stationary sources. Results showed that there is significant effect of blast pressure, feed rate, and surface contamination on TPM emissions. Mathematical equations were developed to estimate emission factors in terms of mass of emissions per unit mass of abrasive used, as well as mass of emissions per unit of surface area cleaned. These equations will help industries in estimating PM emissions based on blast pressure and abrasive feed rate. In addition, emissions can be reduced by choosing optimum operating conditions. PMID:16933653

  20. Atmospheric particulate emissions from dry abrasive blasting using coal slag

    SciTech Connect

    Bhaskar Kura; Kalpalatha Kambham; Sivaramakrishnan Sangameswaran; Sandhya Potana

    2006-08-15

    Coal slag is one of the widely used abrasives in dry abrasive blasting. Atmospheric emissions from this process include particulate matter (PM) and heavy metals, such as chromium, lead, manganese, nickel. Quantities and characteristics of PM emissions depend on abrasive characteristics and process parameters. Emission factors are key inputs to estimate emissions. Experiments were conducted to study the effect of blast pressure, abrasive feed rate, and initial surface contamination on total PM (TPM) emission factors for coal slag. Rusted and painted mild steel surfaces were used as base plates. Blasting was carried out in an enclosed chamber, and PM was collected from an exhaust duct using U.S. Environment Protection Agency source sampling methods for stationary sources. Results showed that there is significant effect of blast pressure, feed rate, and surface contamination on TPM emissions. Mathematical equations were developed to estimate emission factors in terms of mass of emissions per unit mass of abrasive used, as well as mass of emissions per unit of surface area cleaned. These equations will help industries in estimating PM emissions based on blast pressure and abrasive feed rate. In addition, emissions can be reduced by choosing optimum operating conditions. 40 refs., 5 figs., 2 tabs.

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

    PubMed

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

    2010-08-01

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

  2. Performance of High Flow Rate Samplers for Respirable Particle Collection

    PubMed Central

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

    2010-01-01

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

  3. Abrasion-resistant antireflective coating for polycarbonate

    NASA Technical Reports Server (NTRS)

    Wydeven, T. J.

    1978-01-01

    Following plasma-polymerization technique, treatment in oxygen glow discharge further enhances abrasion resistance and transmission. Improvement in abrasion resistance was shown by measuring percentage of haze resulting from abrasion. Coating samples were analyzed for abrasion using standard fresh rubber eraser. Other tests included spectra measurements and elemental analysis with spectrometers and spectrophotometers.

  4. Resistance of dentin coating materials against abrasion by toothbrush.

    PubMed

    Gando, Iori; Ariyoshi, Meu; Ikeda, Masaomi; Sadr, Alireza; Nikaido, Toru; Tagami, Junji

    2013-01-01

    Thin-film coating of root dentin surface by all-in-one adhesives has been shown to be an effective option to prevent root surface caries. The purpose of this study was to investigate the wear resistance against toothbrush abrasion of two all-in-one coating materials; Shield Force (SF) and Hybrid Coat (HC). Bovine dentin surfaces were covered with one of the coating materials; SF or HC. After storage in water for 24 h, the testing surface was subjected to the toothbrush abrasion test up to 50,000 cycles either in water or toothpaste slurry. The remaining thickness of the coating material was measured using SEM. Toothpaste slurry significantly increased rate of tooth brush abrasion of the coating materials. While SF and HC wore at a similar pace under toothbrush abrasion, SF had a thicker coat and could protect dentin longer, up to 50,000 cycles. PMID:23370872

  5. Single chamber fuel cells: Flow geometry, rate and composition considerations

    SciTech Connect

    Stefan, Ionel C.; Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    2003-11-17

    Four different single chamber fuel cell designs were compared using propane-air gas mixtures. Gas flow around the electrodes has a significant influence on the open circuit voltage and the power density of the cell. The strong influence of flow geometry is likely due to its effect on gas composition, particularly on the oxygen chemical potential at the two electrodes as a result of gas mixing. The chamber design which exposes the cathode first to the inlet gas was found to yield the best performance at lower flow rates, while the open tube design with the electrodes equally exposed to the inlet gas worked best at higher flow rates.

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

    PubMed Central

    Abulon, Dina Joy K

    2015-01-01

    Purpose We aimed to investigate effects of instrument settings on porcine vitreous flow rates through dual pneumatic high-speed vitrectomy probes. Methods The CONSTELLATION® Vision System was tested with 250, 450, and 650 mmHg of vacuum using six ULTRAVIT® vitrectomy probes of each diameter (25+®, 25, 23, and 20 gauge) operated from 500 cuts per minute (cpm) up to 5,000 cpm. Duty cycle modes tested included biased open, 50/50, and biased closed. Flow rates were calculated by assessing the change in weight of porcine eyes during vitreous aspiration. Volumetric flow rate was measured with a computer-connected electronic scale. Results At lower cut rates, the biased open mode produced higher flow than did the 50/50 mode, which produced higher flow than did the biased closed mode. In the biased closed and 50/50 modes, vitreous flow rates tended to increase with increasing cut rate. Vitreous flow rates in the biased open duty cycle mode remained relatively constant across cut rates. Conclusion Vitreous flow rates through dual pneumatic vitrectomy probes could be manipulated by changing the duty cycle modes on the vitrectomy system. Differences in duty cycle behavior suggest that high-speed cut rates of 5,000 cpm may optimize vitreous aspiration. PMID:25709386

  7. Abrasives in snuff?

    PubMed

    Dahl, B L; Stølen, S O; Oilo, G

    1989-08-01

    The purpose of this study was to determine and calculate the inorganic contents of four brands of snuff. Visual inspection of wet snuff showed fairly large, yellow crystal-like particles. Scanning electron microscopy and X-ray dispersive (EDX) analyses were used to study both wet snuff and ashes of snuff, whereas light emission spectrography was used to determine elements in the ashes. The crystal-like particles did not dissolve in distilled water or in ethanol heated to 60 degrees C. EDX analyses showed that most elements remained in the particles after washing. The total weight percentage of inorganic material in snuff was calculated after burning dried snuff until constant weight was obtained. The ashes of snuff did not contain any crystal-like particles but consisted of a small-grained amorphous mass. The following elements were detected: Ag, Al, Ba, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, P, Pb, Si, Sr, Ti, Va, and Zr. Other elements such as rare earths were not searched for. The weight percentage of inorganic elements ranged between 12.35 +/- 0.69 and 20.95 +/- 0.81. Provided snuff is used in the same manner as chewing tobacco, and some people admit to doing so, there is a risk that its relatively high contents of inorganic material and heavily soluble salts may be conducive to excessive abrasion of teeth and restorations. PMID:2782061

  8. Turbine flow sensor for volume-flow rate verification in MR.

    PubMed

    Frayne, R; Holdsworth, D W; Smith, R F; Kasrai, R; Larsen, J P; Rutt, B K

    1994-09-01

    A turbine flow sensor for MR flow experiments has been evaluated using reference volume-flow rate measurements obtained using an electromagnetic (EM) flow meter measurements and simultaneous phase contrast (PC) MR acquisitions. After calibration, the device was found to have accuracy (compared with the EM flow meter), linearity, and precision of better than +/- 1%, +/- 3.5%, 3.5%, respectively, in constant flow mode (0 to 30 ml s-1). The frequency response of the flow sensor was flat (within +/- 10%) up to 13.9 Hz. Volume-flow rate measurements on constant and simulated physiologic flow waveforms were in close agreement with both the electromagnetic (EM) flow meter and the gated MR PC estimates. PMID:7984075

  9. Position paper -- Tank ventilation system design air flow rates

    SciTech Connect

    Goolsby, G.K.

    1995-01-04

    The purpose of this paper is to document a project position on required ventilation system design air flow rates for the waste storage tanks currently being designed by project W-236A, the Multi-Function Waste Tank Facility (MWTF). The Title 1 design primary tank heat removal system consists of two systems: a primary tank vapor space ventilation system; and an annulus ventilation system. At the conclusion of Title 1 design, air flow rates for the primary and annulus ventilation systems were 960 scfm and 4,400 scfm, respectively, per tank. These design flow rates were capable of removing 1,250,000 Btu/hr from each tank. However, recently completed and ongoing studies have resulted in a design change to reduce the extreme case heat load to 700,000 Btu/hr. This revision of the extreme case heat load, coupled with results of scale model evaporative testing performed by WHC Thermal Hydraulics, allow for a reduction of the design air flow rates for both primary and annulus ventilation systems. Based on the preceding discussion, ICF Kaiser Hanford Co. concludes that the design should incorporate the following design air flow rates: Primary ventilation system--500 scfm maximum and Annulus ventilation system--1,100 scfm maximum. In addition, the minimum air flow rates in the primary and annulus ventilation systems will be investigated during Title 2 design. The results of the Title 2 investigation will determine the range of available temperature control using variable air flows to both ventilation systems.

  10. Conduit Coating Abrasion Testing

    NASA Technical Reports Server (NTRS)

    Sullivan, Mary K.

    2013-01-01

    During my summer internship at NASA I have been working alongside the team members of the RESTORE project. Engineers working on the RESTORE project are creating ·a device that can go into space and service satellites that no longer work due to gas shortage or other technical difficulties. In order to complete the task of refueling the satellite a hose needs to be used and covered with a material that can withstand effects of space. The conduit coating abrasion test will help the researchers figure out what type of thermal coating to use on the hose that will be refueling the satellites. The objective of the project is to determine whether or not the conduit coating will withstand the effects of space. For the RESTORE project I will help with various aspects of the testing that needed to be done in order to determine which type of conduit should be used for refueling the satellite. During my time on the project I will be assisting with wiring a relay board that connected to the test set up by soldering, configuring wires and testing for continuity. Prior to the testing I will work on creating the testing site and help write the procedure for the test. The testing will take place over a span of two weeks and lead to an informative conclusion. Working alongside various RESTORE team members I will assist with the project's documentation and records. All in all, throughout my internship at NASA I hope to learn a number of valuable skills and be a part of a hard working team of engineers.

  11. Fluid/Vapor Separator for Variable Flow Rates

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  12. Rock Cutting Depth Model Based on Kinetic Energy of Abrasive Waterjet

    NASA Astrophysics Data System (ADS)

    Oh, Tae-Min; Cho, Gye-Chun

    2016-03-01

    Abrasive waterjets are widely used in the fields of civil and mechanical engineering for cutting a great variety of hard materials including rocks, metals, and other materials. Cutting depth is an important index to estimate operating time and cost, but it is very difficult to predict because there are a number of influential variables (e.g., energy, geometry, material, and nozzle system parameters). In this study, the cutting depth is correlated to the maximum kinetic energy expressed in terms of energy (i.e., water pressure, water flow rate, abrasive feed rate, and traverse speed), geometry (i.e., standoff distance), material (i.e., α and β), and nozzle system parameters (i.e., nozzle size, shape, and jet diffusion level). The maximum kinetic energy cutting depth model is verified with experimental test data that are obtained using one type of hard granite specimen for various parameters. The results show a unique curve for a specific rock type in a power function between cutting depth and maximum kinetic energy. The cutting depth model developed here can be very useful for estimating the process time when cutting rock using an abrasive waterjet.

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

    PubMed

    Zhou, Yue; Cheng, Yung-Sung

    2010-02-01

    The Institute of Occupational Medicine (IOM) personal sampler is usually operated at a flow rate of 2.0 L/min, the rate at which it was designed and calibrated, for sampling the inhalable mass fraction of airborne particles in occupational environments. In an environment of low aerosol concentrations only small amounts of material are collected, and that may not be sufficient for analysis. Recently, a new sampling pump with a flow rate up to 15 L/min became available for personal samplers, with the potential of operating at higher flow rates. The flow rate of a Leland Legacy sampling pump, which operates at high flow rates, was evaluated and calibrated, and its maximum flow was found to be 10.6 L/min. IOM samplers were placed on a mannequin, and sampling was conducted in a large aerosol wind tunnel at wind speeds of 0.56 and 2.22 m/s. Monodisperse aerosols of oleic acid tagged with sodium fluorescein in the size range of 2 to 100 microm were used in the test. The IOM samplers were operated at flow rates of 2.0 and 10.6 L/min. Results showed that the IOM samplers mounted in the front of the mannequin had a higher sampling efficiency than those mounted at the side and back, regardless of the wind speed and flow rate. For the wind speed of 0.56 m/s, the direction-averaged (the average value of all orientations facing the wind direction) sampling efficiency of the samplers operated at 2.0 L/min was slightly higher than that of 10.6 L/min. For the wind speed of 2.22 m/s, the sampling efficiencies at both flow rates were similar for particles < 60 microm. The results also show that the IOM's sampling efficiency at these two different flow rates follows the inhalable mass curve for particles in the size range of 2 to 20 microm. The test results indicate that the IOM sampler can be used at higher flow rates. PMID:19953412

  14. Studies on pressure losses and flow rate optimization in vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Tang, Ao; Bao, Jie; Skyllas-Kazacos, Maria

    2014-02-01

    Premature voltage cut-off in the operation of the vanadium redox flow battery is largely associated with the rise in concentration overpotential at high state-of-charge (SOC) or state-of-discharge (SOD). The use of high constant volumetric flow rate will reduce concentration overpotential, although potentially at the cost of consuming excessive pumping energy which in turn lowers system efficiency. On the other hand, any improper reduction in flow rate will also limit the operating SOC and lead to deterioration in battery efficiency. Pressure drop losses are further exacerbated by the need to reduce shunt currents in flow battery stacks that requires the use of long, narrow channels and manifolds. In this paper, the concentration overpotential is modelled as a function of flow rate in an effort to determine an appropriate variable flow rate that can yield high system efficiency, along with the analysis of pressure losses and total pumping energy. Simulation results for a 40-cell stack under pre-set voltage cut-off limits have shown that variable flow rates are superior to constant flow rates for the given system design and the use of a flow factor of 7.5 with respect to the theoretical flow rate can reach overall high system efficiencies for different charge-discharge operations.

  15. Estimating rates of debris flow entrainment from ground vibrations

    NASA Astrophysics Data System (ADS)

    Kean, J. W.; Coe, J. A.; Coviello, V.; Smith, J. B.; McCoy, S. W.; Arattano, M.

    2015-08-01

    Debris flows generate seismic waves as they travel downslope and can become more dangerous as they entrain sediment along their path. We present field observations that show a systematic relation between the magnitude of seismic waves and the amount of erodible sediment beneath the flow. Specifically, we observe that a debris flow traveling along a channel filled initially with sediment 0.34 m thick generates about 2 orders of magnitude less spectral power than a similar-sized flow over the same channel without sediment fill. We adapt a model from fluvial seismology to explain this observation and then invert it to estimate the level of bed sediment (and rate of entrainment) beneath a passing series of surges. Our estimates compare favorably with previous direct measurements of entrainment rates at the site, suggesting the approach may be a new indirect way to obtain rare field constraints needed to test models of debris flow entrainment.

  16. A modified ASTM G-75 abrasion test helps select candidate alloys for service in a corrosive and abrasive slurry

    SciTech Connect

    Corbett, R.A.; Morrison, W.S.; Jenkins, C.F.; Westinghouse Savannah River Co., Aiken, SC )

    1989-01-01

    The design of a hazardous waste immobilization facility at the Savannah River Site (SRS) set material requirements for both abrasion resistance and corrosion resistance in process equipment. Standard ASTM slurry wear test G75 was modified to permit evaluation and comparison of abrasive resistance of candidate materials of construction in the laboratory. However, corrosion was found to contribute significantly to overall metal loss during the testing. Consequently, the abrasive slurry used for the testing was modified by adjusting its chemistry to include appropriate corrosive species. The Miller numbers obtained in the modified G75 Miller abrasion test are described. Pilot plant observations for Type 304L austenitic stainless steel were available. These data were used to generate a Morrison-Miller Ratio'' in order to determine anticipated field abrasion properties for other alloys. Hardness for many of the alloys fell in a narrow range about Rockwell B90, but performance varied significantly in response to slurry chemistry. This effect if synergistic may often be overlooked in the selection process, and it needs to be addressed. Some pilot plant testing of other alloys is essential to confirm the calculated abrasion rates and the approach of using the Morrison-Miller ratio. 6 refs., 3 figs., 5 tabs.

  17. Flow rate limitation in open wedge channel under microgravity

    NASA Astrophysics Data System (ADS)

    Wei, YueXing; Chen, XiaoQian; Huang, YiYong

    2013-08-01

    A study of flow rate limitation in an open wedge channel is reported in this paper. Under microgravity condition, the flow is controlled by the convection and the viscosity in the channel as well as the curvature of the liquid free surface. A maximum flow rate is achieved when the curvature cannot balance the pressure difference leading to a collapse of the free surface. A 1-dimensional theoretical model is used to predict the critical flow rate and calculate the shape of the free surface. Computational Fluid Dynamics tool is also used to simulate the phenomenon. Results show that the 1-dimensional model overestimates the critical flow rate because extra pressure loss is not included in the governing equation. Good agreement is found in 3-dimensional simulation results. Parametric study with different wedge angles and channel lengths show that the critical flow rate increases with increasing the cross section area; and decreases with increasing the channel length. The work in this paper can help understand the surface collapsing without gravity and for the design in propellant management devices in satellite tanks.

  18. Rate-based ABR flow control using two timescale SPSA

    NASA Astrophysics Data System (ADS)

    Bhatnagar, Shalabh; Fu, Michael C.; Marcus, Steven I.

    1999-08-01

    In this paper, a two timescale simultaneous perturbation stochastic approximation algorithm is developed and applied to closed loop rate based available bit rate flow control. The relevant convergence results are stated and explained. Numerical experiments demonstrate fast convergence even in the presence of significant delays and a large number of parameterized policy levels.

  19. Granular flow through an aperture: pressure and flow rate are independent.

    PubMed

    Aguirre, María Alejandra; Grande, Juan Gabriel; Calvo, Adriana; Pugnaloni, Luis A; Géminard, Jean-Christophe

    2011-06-01

    We simultaneously measure the flow rate and the normal force on the base, near the outlet, during the discharge through an orifice of a dense packing of monosized disks driven by a conveyor belt. We find that the normal force on the base decreases even when a constant flow rate is measured. In addition, we show, by changing the mass of the disks, that pressure can be changed while the flow rate remains constant. Conversely, we are able, by changing the belt velocity, to set different flow rates for the same pressure. The experiment confirms that, contrary to what has been implicitly assumed in numerous works, the flow rate through an aperture is not controlled by the pressure in the outlet region. PMID:21797356

  20. MASS ACCRETION RATE OF ROTATING VISCOUS ACCRETION FLOW

    SciTech Connect

    Park, Myeong-Gu

    2009-11-20

    The mass accretion rate of transonic spherical accretion flow onto compact objects such as black holes is known as the Bondi accretion rate, which is determined only by the density and the temperature of gas at the outer boundary. A rotating accretion flow has angular momentum, which modifies the flow profile from the spherical Bondi flow, and hence its mass accretion rate, but most work on disc accretion has taken the mass flux to be given with the relation between that parameter and external conditions left uncertain. Within the framework of a slim alpha disk, we have constructed global solutions of the rotating, viscous, hot accretion flow in the Paczynski-Wiita potential and determined its mass accretion rate as a function of density, temperature, and angular momentum of gas at the outer boundary. We find that the low angular momentum flow resembles the spherical Bondi flow and its mass accretion rate approaches the Bondi accretion rate for the same density and temperature at the outer boundary. The high angular momentum flow on the other hand is the conventional hot accretion disk with advection, but its mass accretion rate can be significantly smaller than the Bondi accretion rate with the same boundary conditions. We also find that solutions exist only within a limited range of dimensionless mass accretion rate m-dotident toM-dot/M-dot{sub B}, where M-dot is the mass accretion rate and M-dot{sub B} is the Bondi accretion rate: when the temperature at the outer boundary is equal to the virial temperature, solutions exist only for 0.05approxrate is roughly independent of the radius of the outer boundary but inversely proportional to the angular momentum at the outer boundary and proportional to the viscosity parameter, m-dotapprox =9.0 alphalambda{sup -1} when 0.1 approx

  1. Induction and measurement of minute flow rates through nanopipes

    NASA Astrophysics Data System (ADS)

    Sinha, Shashank; Pia Rossi, Maria; Mattia, D.; Gogotsi, Yury; Bau, Haim H.

    2007-01-01

    A simple technique to simultaneously induce fluid flow through an individual nanopipe and measure the flow rate and the pressure difference across the pipe is described. Two liquid drops of different sizes are positioned at the two ends of the nanopipe. Due to the higher capillary pressure of the smaller drop, flow is driven from the smaller drop to the bigger drop. The instantaneous pressures of the two drops are estimated from the drops' shapes and sizes. The flow rate is estimated by monitoring the sizes of the drops as functions of time with a microscope and a video camera. A theory that correlates the drops' sizes and the flow rate is derived. Measurements are carried out with an ionic salt and glycerin to estimate the effective tube radius of the nanopipes with diameters ranging from 200 to 300nm. The tubes' diameters are independently measured with a scanning electron microscope. The method is also verified by tracking the motion of fluorescent particles through the nanopipe. The paper provides a simple technique for studying extremely low flow rates in nanofluidic systems. When working with low-evaporation fluids such as ionic salts, the measurements can be carried out with an electron microscope.

  2. First-order control of surface roughness at three scales: boundary layer dynamics, tracer dispersion and pebble abrasion

    NASA Astrophysics Data System (ADS)

    Jerolmack, D. J.; Litwin, K. L.; Phillips, C. B.; Martin, R. L.

    2012-12-01

    In many situations it may be appropriate to treat surfaces as smooth and particles as spherical, however here we focus on scenarios in which the roughness of the surface exerts a first-order control on flow and transport dynamics. We describe three vignettes at three different scales: (1) roughness transitions and resulting sediment transport dynamics over ~10-km distance in a desert dune field; (2) reach-scale river bed roughness and its influence on dispersion of tracer particles in bed load; and (3) the control of particle surface roughness on the nature and rate of pebble abrasion. For (1), we show how the abrupt transition from a flat surface to a dune field may be treated as a step increase in the aerodynamic roughness parameter - so long as the spatial scale considered is significantly larger than that of an individual dune. This increase causes a spatial decline in the boundary stress downwind that may be understood using simple boundary layer theory, resulting in a factor of three decrease in the sand flux over a distance of kilometers. For (2), laboratory and field studies of tracer particles in bed load indicate that they undergo short flights separated by long rest periods having a power-law tail - even in steady flows. We hypothesize that for near-threshold transport - which predominates is coarse-grained rivers - particles become trapped in 'wells' produced by surface roughness, and their rest time is controlled by the time for the surface to scour down and release them. Laboratory observations support this hypothesis, while comparison to non-geophysical 'flows' indicates that these dynamics are generic to transport in disordered systems. Finally, for (3) we report laboratory experiments by our group and others showing how abrasion rate decreases with decreasing particle roughness. Geometric models quantitatively support the intuition that locations of high positive curvature on pebble surfaces are more susceptible to abrasion; as they are

  3. Comparing the Air Abrasion Cutting Efficacy of Dentine Using a Fluoride-Containing Bioactive Glass versus an Alumina Abrasive: An In Vitro Study.

    PubMed

    Tan, Melissa H X; Hill, Robert G; Anderson, Paul

    2015-01-01

    Air abrasion as a caries removal technique is less aggressive than conventional techniques and is compatible for use with adhesive restorative materials. Alumina, while being currently the most common abrasive used for cutting, has controversial health and safety issues and no remineralisation properties. The alternative, a bioactive glass, 45S5, has the advantage of promoting hard tissue remineralisation. However, 45S5 is slow as a cutting abrasive and lacks fluoride in its formulation. The aim of this study was to compare the cutting efficacy of dentine using a customised fluoride-containing bioactive glass Na0SR (38-80 μm) versus the conventional alumina abrasive (29 μm) in an air abrasion set-up. Fluoride was incorporated into Na0SR to enhance its remineralisation properties while strontium was included to increase its radiopacity. Powder outflow rate was recorded prior to the cutting tests. Principal air abrasion cutting tests were carried out on pristine ivory dentine. The abrasion depths were quantified and compared using X-ray microtomography. Na0SR was found to create deeper cavities than alumina (p < 0.05) despite its lower powder outflow rate and predictably reduced hardness. The sharper edges of the Na0SR glass particles might improve the cutting efficiency. In conclusion, Na0SR was more efficacious than alumina for air abrasion cutting of dentine. PMID:26697067

  4. Comparing the Air Abrasion Cutting Efficacy of Dentine Using a Fluoride-Containing Bioactive Glass versus an Alumina Abrasive: An In Vitro Study

    PubMed Central

    Tan, Melissa H. X.; Hill, Robert G.; Anderson, Paul

    2015-01-01

    Air abrasion as a caries removal technique is less aggressive than conventional techniques and is compatible for use with adhesive restorative materials. Alumina, while being currently the most common abrasive used for cutting, has controversial health and safety issues and no remineralisation properties. The alternative, a bioactive glass, 45S5, has the advantage of promoting hard tissue remineralisation. However, 45S5 is slow as a cutting abrasive and lacks fluoride in its formulation. The aim of this study was to compare the cutting efficacy of dentine using a customised fluoride-containing bioactive glass Na0SR (38–80 μm) versus the conventional alumina abrasive (29 μm) in an air abrasion set-up. Fluoride was incorporated into Na0SR to enhance its remineralisation properties while strontium was included to increase its radiopacity. Powder outflow rate was recorded prior to the cutting tests. Principal air abrasion cutting tests were carried out on pristine ivory dentine. The abrasion depths were quantified and compared using X-ray microtomography. Na0SR was found to create deeper cavities than alumina (p < 0.05) despite its lower powder outflow rate and predictably reduced hardness. The sharper edges of the Na0SR glass particles might improve the cutting efficiency. In conclusion, Na0SR was more efficacious than alumina for air abrasion cutting of dentine. PMID:26697067

  5. Packet Scheduling Mechanism to Improve Quality of Short Flows and Low-Rate Flows

    NASA Astrophysics Data System (ADS)

    Yokota, Kenji; Asaka, Takuya; Takahashi, Tatsuro

    In recent years elephant flows are increasing by expansion of peer-to-peer (P2P) applications on the Internet. As a result, bandwidth is occupied by specific users triggering unfair resource allocation. The main packet-scheduling mechanism currently employed is first-in first-out (FIFO) where the available bandwidth of short flows is limited by elephant flows. Least attained service (LAS), which decides transfer priority of packets by the total amount of transferred data in all flows, was proposed to solve this problem. However, routers with LAS limit flows with large amount of transferred data even if they are low-rate. Therefore, it is necessary to improve the quality of low-rate flows with long holding times such as voice over Internet protocol (VoIP) applications. This paper proposes rate-based priority control (RBPC), which calculates the flow rate and control the priority by using it. Our proposed method can transfer short flows and low-rate flows in advance. Moreover, its fair performance is shown through simulations.

  6. Effect of viscoelasticity on the flow pattern and the volumetric flow rate in electroosmotic flows through a microchannel.

    PubMed

    Park, H M; Lee, W M

    2008-07-01

    Many lab-on-a-chip based microsystems process biofluids such as blood and DNA solutions. These fluids are viscoelastic and show extraordinary flow behaviors, not existing in Newtonian fluids. Adopting appropriate constitutive equations these exotic flow behaviors can be modeled and predicted reasonably using various numerical methods. In the present paper, we investigate viscoelastic electroosmotic flows through a rectangular straight microchannel with and without pressure gradient. It is shown that the volumetric flow rates of viscoelastic fluids are significantly different from those of Newtonian fluids under the same external electric field and pressure gradient. Moreover, when pressure gradient is imposed on the microchannel there appear appreciable secondary flows in the viscoelastic fluids, which is never possible for Newtonian laminar flows through straight microchannels. The retarded or enhanced volumetric flow rates and secondary flows affect dispersion of solutes in the microchannel nontrivially. PMID:18584093

  7. Effects of Mass Flow Rate on the Thermal-Flow Characteristics of Microwave CO2 Plasma.

    PubMed

    Hong, Chang-Ki; Na, Young-Ho; Uhm, Han-Sup; Kim, Youn-Jea

    2015-03-01

    In this study, the thermal-flow characteristics of atmospheric pressure microwave CO2 plasma were numerically investigated by simulation. The electric and gas flow fields in the reaction chamber with a microwave axial injection torch operated at 2.45 GHz were simulated. The microwave launcher had the standard rectangular waveguide WR340 geometry. The simulation was performed by using the COMSOL Multiphysics plasma model with various mass flow rates of CO2. The electric fields, temperature profiles and the density of electrons were graphically depicted for different CO2 inlet mass flow rates. PMID:26413663

  8. Comparison of saturation flow rates at signalized intersections

    SciTech Connect

    Stokes, R.W.

    1988-11-01

    The intersection, being the focal point of conflicts and congestion in the roadway network, is a critical area in the efficient use of the urban street system. As a result, the capacity of the intersection, particularly the signalized intersection, has been the subject of much research in recent years. Procedures for estimating signalized intersection capacity are typically based on the use of an ideal, maximum traffic flow rate (saturation flow) that is adjusted to reflect site-specific conditions that may not be ideal. Regardless of the specific procedure used in signalized intersection capacity analyses, saturates flow is used as the base flow rate. Various capacity influencing factors are then used to modify this base flow value to reflect prevailing conditions. This article presents a brief review of studied conducted to estimate saturation flows at signalized intersections. Given the sensitivity of signalized intersection capacity analysis procedures to saturation flow values, the information presented here should be of interest to the practitioner, as well as the theorist.

  9. Entropy production rates from viscous flow calculations. I - A turbulent boundary layer flow

    NASA Astrophysics Data System (ADS)

    Moore, J.; Moore, J. G.

    1983-03-01

    A procedure for obtaining entropy production rates from viscous flow calculations is described. The method is based on process thermodynamics; it allows loss production to be calculated in 'irreversible equilibrium processes'. The two-dimensional turbulent boundary layer of Samuel and Joubert is considered. Mean rates of entropy production are evaluated from measured data using rates of dissipation and rates of increase of turbulence kinetic energy. Calculations performed with the Moore Cascade Flow Program give good agreement with mean rates of entropy production and reveal details of the distribution of entropy production throughout the boundary layer.

  10. Low-Flow-Rate Dry-Powder Feeder

    NASA Technical Reports Server (NTRS)

    Ramsey, Keith E.

    1994-01-01

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

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

    PubMed

    Ma, Rong-Hua; Wang, Dung-An; Hsueh, Tzu-Han; Lee, Chia-Yen

    2009-01-01

    This study develops a MEMS-based low-cost sensing platform for sensing gas flow rate and flow direction comprising four silicon nitride cantilever beams arranged in a cross-form configuration, a circular hot-wire flow meter suspended on a silicon nitride membrane, and an integrated resistive temperature detector (RTD). In the proposed device, the flow rate is inversely derived from the change in the resistance signal of the flow meter when exposed to the sensed air stream. To compensate for the effects of the ambient temperature on the accuracy of the flow rate measurements, the output signal from the flow meter is compensated using the resistance signal generated by the RTD. As air travels over the surface of the cross-form cantilever structure, the upstream cantilevers are deflected in the downward direction, while the downstream cantilevers are deflected in the upward direction. The deflection of the cantilever beams causes a corresponding change in the resistive signals of the piezoresistors patterned on their upper surfaces. The amount by which each beam deflects depends on both the flow rate and the orientation of the beam relative to the direction of the gas flow. Thus, following an appropriate compensation by the temperature-corrected flow rate, the gas flow direction can be determined through a suitable manipulation of the output signals of the four piezoresistors. The experimental results have confirmed that the resulting variation in the output signals of the integrated sensors can be used to determine not only the ambient temperature and the velocity of the air flow, but also its direction relative to the sensor with an accuracy of ± 7.5° error. PMID:22346708

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

    PubMed Central

    Ma, Rong-Hua; Wang, Dung-An; Hsueh, Tzu-Han; Lee, Chia-Yen

    2009-01-01

    This study develops a MEMS-based low-cost sensing platform for sensing gas flow rate and flow direction comprising four silicon nitride cantilever beams arranged in a cross-form configuration, a circular hot-wire flow meter suspended on a silicon nitride membrane, and an integrated resistive temperature detector (RTD). In the proposed device, the flow rate is inversely derived from the change in the resistance signal of the flow meter when exposed to the sensed air stream. To compensate for the effects of the ambient temperature on the accuracy of the flow rate measurements, the output signal from the flow meter is compensated using the resistance signal generated by the RTD. As air travels over the surface of the cross-form cantilever structure, the upstream cantilevers are deflected in the downward direction, while the downstream cantilevers are deflected in the upward direction. The deflection of the cantilever beams causes a corresponding change in the resistive signals of the piezoresistors patterned on their upper surfaces. The amount by which each beam deflects depends on both the flow rate and the orientation of the beam relative to the direction of the gas flow. Thus, following an appropriate compensation by the temperature-corrected flow rate, the gas flow direction can be determined through a suitable manipulation of the output signals of the four piezoresistors. The experimental results have confirmed that the resulting variation in the output signals of the integrated sensors can be used to determine not only the ambient temperature and the velocity of the air flow, but also its direction relative to the sensor with an accuracy of ± 7.5° error. PMID:22346708

  13. High strain-rate plastic flow in Fe and Al

    NASA Astrophysics Data System (ADS)

    Smith, Raymond; Eggert, Jon; Rudd, Robert; Bolme, Cynthia; Collins, Gilbert

    2011-06-01

    Understanding the nature and time-dependence of material deformation at high strain rates is an important goal in condensed matter physics. Under dynamic loading, the rate of plastic strain is determined by the flow of dislocations through the crystal lattice and is a complex function of time, distance, sample purity, temperature, internal stresses, microstructure and strain rate. Under shock compression time-dependent plasticity is typically inferred by fitting elastic precursor stresses as a function of propagation distance with a phenomenologically based dislocation kinetics model. We employ a laser-driven ramp wave loading technique to compress 6-70 micron thick samples of bcc-Fe and fcc-Al over a strain rate range of 1e6-1e8 1/s. Our data show that for fixed sample thickness, stresses associated the onset of plasticity are highly dependent on the strain rate of compression and do not readily fit into the elastic stress - distance evolution descriptive of instantaneous shock loading. We find that the elastic stress at the onset of plasticity is well correlated with the strain rate at the onset of plastic flow for both shock- and ramp-wave experiments. Our data, combined with data from other dynamic compression platforms, reveal a sharp increase in the peak elastic stress at high strain rates, consistent with a transition in dislocation flow dominated by phonon drag. smith248@llnl.gov

  14. Measuring gas flow rates in the Milky Way

    NASA Astrophysics Data System (ADS)

    Wakker, Bart

    2010-09-01

    Gas flows out of and into the Milky Way are a crucial element in its evolution. Supernovae heat gas in the disk and lift it into the halo. Tidal streams and instabilities in the hot Galactic corona result in an inflow of low-metallicity gas. These flows can be observed in the form of the high-velocity clouds {HVCs}. Their location, brightness, distances, ionization structure and metallicities can be used to determine the conditions in the gaseous disk and halo as well as the rate of mass flow corresponding to the different processes. So far, sufficient information to derive an associated mass flow rate is available for just 5 HVCs. We propose to observe 20 AGNs toward most of the other HVC complexes as well as toward a few small clouds, in order to derive a metallicity for almost every HVC complex, which will complement distance measurements that have been or will be obtained in our ongoing program. Combining all the data, we can derive {a} the rate of the circulation of gas between disk and halo, constraining the Galactic supernova rate and {b} the accretion rate of low-metallicity material that feeds star formation over 10 Gyr, which will constrain both models of galactic chemical evolution and models of the conditions in the hot galactic corona.

  15. Theoretical Analysis of Maximum Flow Declination Rate versus Maximum Area Declination Rate in Phonation

    ERIC Educational Resources Information Center

    Titze, Ingo R.

    2006-01-01

    Purpose: Maximum flow declination rate (MFDR) in the glottis is known to correlate strongly with vocal intensity in voicing. This declination, or negative slope on the glottal airflow waveform, is in part attributable to the maximum area declination rate (MADR) and in part to the overall inertia of the air column of the vocal tract (lungs to…

  16. A model for reaction rates in turbulent reacting flows

    NASA Technical Reports Server (NTRS)

    Chinitz, W.; Evans, J. S.

    1984-01-01

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

  17. Study of the crevicular fluid flow rate in smokers.

    PubMed

    Rosa, G M; Lucas, G Q; Lucas, O N

    2000-01-01

    The purpose of this study was to investigate if smoking--a risk factor in periodontal disease-affects the crevicular fluid (CF) flow rate. Twenty-nine dental students were included in the control group--non-smokers- (NS) and 34 in the experimental group--smokers- (S). All subjects were enrolled in a rigorous dental hygiene program (RDHP). The Greene-Vermillion plaque index, and Löe-Silness gingival index (GI) were recorded. CF was obtained and measured with the Periotron 8000. These recordings were made before and after the RDHP. The results show that the CF mean flow rate was slightly lower in the S group than in the NS group, for both recordings. The analysis of the relation between the CF flow rate and the GI recorded in the dental surfaces, revealed a significantly lower flow rate in the S group for GI 1 (p < 0.01) and GI 3 (p < 0.05). The difference observed between the S and NS groups, may be due to the vasoconstrictor action of the cigarette components (nicotine and/or metabolites) on the gingival vasculature. PMID:11885468

  18. 93. TEMPERATURE AND FLOW RATE CONTROLS FOR SYSTEM 1 AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    93. TEMPERATURE AND FLOW RATE CONTROLS FOR SYSTEM 1 AND SYSTEM 2, FACING WEST IN MECHANICAL EQUIPMENT ROOM (101), LSB (BLDG. 770) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  19. Effects of argon gas flow rate on laser-welding.

    PubMed

    Takayama, Yasuko; Nomoto, Rie; Nakajima, Hiroyuki; Ohkubo, Chikahiro

    2012-01-01

    The purpose of this study was to evaluate the effects of the rate of argon gas flow on joint strength in the laser-welding of cast metal plates and to measure the porosity. Two cast plates (Ti and Co-Cr alloy) of the same metal were abutted and welded together. The rates of argon gas flow were 0, 5 and 10 L/min for the Co-Cr alloy, and 5 and 10 L/min for the Ti. There was a significant difference in the ratio of porosity according to the rate of argon gas flow in the welded area. Argon shielding had no significant effect on the tensile strength of Co-Cr alloy. The 5 L/min specimens showed greater tensile strength than the 10 L/min specimens for Ti. Laser welding of the Co-Cr alloy was influenced very little by argon shielding. When the rate of argon gas flow was high, joint strength decreased for Ti. PMID:22447067

  20. Calibration of high flow rate thoracic-size selective samplers.

    PubMed

    Lee, Taekhee; Thorpe, Andrew; Cauda, Emanuele; Harper, Martin

    2016-01-01

    High flow rate respirable size selective samplers, GK4.126 and FSP10 cyclones, were calibrated for thoracic-size selective sampling in two different laboratories. The National Institute for Occupational Safety and Health (NIOSH) utilized monodisperse ammonium fluorescein particles and scanning electron microscopy to determine the aerodynamic particle size of the monodisperse aerosol. Fluorescein intensity was measured to determine sampling efficiencies of the cyclones. The Health Safety and Laboratory (HSL) utilized a real time particle sizing instrument (Aerodynamic Particle Sizer) and polydisperse glass sphere particles and particle size distributions between the cyclone and reference sampler were compared. Sampling efficiency of the cyclones were compared to the thoracic convention defined by the American Conference of Governmental Industrial Hygienists (ACGIH)/Comité Européen de Normalisation (CEN)/International Standards Organization (ISO). The GK4.126 cyclone showed minimum bias compared to the thoracic convention at flow rates of 3.5 l min(-1) (NIOSH) and 2.7-3.3 l min(-1) (HSL) and the difference may be from the use of different test systems. In order to collect the most dust and reduce the limit of detection, HSL suggested using the upper end in range (3.3 l min(-1)). A flow rate of 3.4 l min(-1) would be a reasonable compromise, pending confirmation in other laboratories. The FSP10 cyclone showed minimum bias at the flow rate of 4.0 l min(-1) in the NIOSH laboratory test. The high flow rate thoracic-size selective samplers might be used for higher sample mass collection in order to meet analytical limits of quantification. PMID:26891196

  1. Calibration of high flow rate thoracic-size selective samplers

    PubMed Central

    Lee, Taekhee; Thorpe, Andrew; Cauda, Emanuele; Harper, Martin

    2016-01-01

    High flow rate respirable size selective samplers, GK4.126 and FSP10 cyclones, were calibrated for thoracic-size selective sampling in two different laboratories. The National Institute for Occupational Safety and Health (NIOSH) utilized monodisperse ammonium fluorescein particles and scanning electron microscopy to determine the aerodynamic particle size of the monodisperse aerosol. Fluorescein intensity was measured to determine sampling efficiencies of the cyclones. The Health Safety and Laboratory (HSL) utilized a real time particle sizing instrument (Aerodynamic Particle Sizer) and poly-disperse glass sphere particles and particle size distributions between the cyclone and reference sampler were compared. Sampling efficiency of the cyclones were compared to the thoracic convention defined by the American Conference of Governmental Industrial Hygienists (ACGIH)/Comité Européen de Normalisation (CEN)/International Standards Organization (ISO). The GK4.126 cyclone showed minimum bias compared to the thoracic convention at flow rates of 3.5 l min−1 (NIOSH) and 2.7–3.3 l min−1 (HSL) and the difference may be from the use of different test systems. In order to collect the most dust and reduce the limit of detection, HSL suggested using the upper end in range (3.3 l min−1). A flow rate of 3.4 l min−1 would be a reasonable compromise, pending confirmation in other laboratories. The FSP10 cyclone showed minimum bias at the flow rate of 4.0 l min−1 in the NIOSH laboratory test. The high flow rate thoracic-size selective samplers might be used for higher sample mass collection in order to meet analytical limits of quantification. PMID:26891196

  2. Inflow rates and interrupted flow effects on concentrated flow erosion and intake rate in two soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface irrigation is the most widely used irrigation practice world wide, but its water use efficiency is low. Interrupted supply of water to furrows may reduce intake rate (IR) upstream and improve irrigation efficiency in many soils, but has an insignificant effect in others. Similarly, intermitt...

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

    NASA Astrophysics Data System (ADS)

    Carreras, Pilar; Gonzalez, Itziar; Ahumada, Oscar

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

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

    PubMed Central

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

    2012-01-01

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

  5. Aeolian Abrasion, a Dominant Erosion Agent in the Martian Environment

    NASA Astrophysics Data System (ADS)

    Bridges, N.; Cooper, G.; Eddlemon, E.; Greeley, R.; Laity, J.; Phoreman, J.; Razdan, A.; van Note, S.; White, B.; Wilson, G.

    2004-12-01

    Aeolian abrasion is one of the predominant erosion mechanisms on Mars today. Martian ventifacts record the climate under which the rocks were modified (wind direction, wind speeds and particle flux) and therefore tie into the overall climatic regime of the planet. By better understanding the rates at which rocks abrade and the features diagnostic of specific climatic conditions, we can gain insight into past climates. Herein we report on numerical models, wind tunnel experiments, and field work to determine 1) Particle and kinetic fluxes on Earth and Mars, 2) the degree to which these parameters control abrasion, and 3) how, in detail, rocks of various shapes and compositions erode over time. Kinetic energy generally increases with height, whereas flux decreases, and impact angles, which affect energy transfer, and rebound effects are functions of the rock facet angle. This results in a non-linear relationship between abrasion potential and height that is a function of wind speed, planetary environment, and target geometry. We have computed the first three of these parameters numerically using a numerical saltation code, combined with published flux calculations These results have been compared to wind tunnel tests of flux vs. height, abrasion of erodible targets, and high speed video analysis under terrestrial and Martian pressures. We are also using high resolution laser scanning to characterize textures, shapes, and weathering changes for terrestrial and Martian rocks at the 100s of microns scale. We find that facet angle, texture, and rock heterogeneity are of critical importance in determining the rate and style of abrasion. Field and theoretical results demonstrate that high speed winds, not the integrated flux of lower speeds, and sand, not dust, produce most rock abrasion. On Mars, this requires sustained winds above 20-25 m/s at the near surface, a challenge in the current environment.

  6. Demystifying ratings: How flow control shocks credit quality

    SciTech Connect

    Martin, J.H.

    1998-07-01

    Financial operations of many solid waste systems, waste-to-energy facilities in particular, have been shocked by the lack of congressional, and state and local legislation to resolve the loss of legal flow control. Flow control is a system's legal authority to direct waste into its own facilities. In contrast is economic flow control, where the market factors prevail and waste is brought to a facility based on competitive pricing. The loss of legal flow control threatens solid waste systems and impinges their underlying credit quality. Credit quality is expressed as the bond rating, a statement about the borrowers ability and willingness to repay debt in full and on time. While the courts have identified acceptable alternatives to enable municipal systems to diversity revenues (creating revenue flexibility), such alternatives may not be palatable as they represent additional taxation or fees. The paper highlights how the loss of legal flow control has shocked the operations, management and credit quality of solid waste systems. These shocks have stimulated public and private partnerships in order to facilitate economic flow control. Municipal credit solutions, credit impacts and credit trends are explained to identify how solid waste systems have responded in an operating climate exacerbated by regulatory changes (environmental and accounting) as well as utility deregulations. Analytical considerations are presented for evaluating the credit quality of solid waste bonds.

  7. Abrasive swivel assembly and method

    DOEpatents

    Hashish, Mohamed; Marvin, Mark

    1990-01-01

    An abrasive swivel assembly for providing a rotating, particle-laden fluid stream and, ultimately, a rotating particle-laden fluid jet is disclosed herein. This assembly includes a tubular arrangement for providing a particle-free stream of fluid, a swivel assembly for rotating a section of the tubular arrangement, and a tubular end section for introducing solid particles into the particle-free fluid stream at a point along the rotating tubular section, whereby to produce a particle-laden fluid stream. This last-mentioned stream can then be used in combination with a cooperating nozzle arrangement for providing a rotating particle-laden fluid jet. In an actual working embodiment, the fluid stream is of sufficiently high pressure so that the abrasive jet can be used as a cutting jet.

  8. Abrasive swivel assembly and method

    DOEpatents

    Hashish, Mohamed; Marvin, Mark

    1989-01-01

    An abrasive swivel assembly for providing a rotating, particle-laden fluid stream and, ultimately, a rotating particle-laden fluid jet is disclosed herein. This assembly includes a tubular arrangement for providing a particle-free stream of fluid, means for rotating a section of the tubular arrangement, and means for introducing solid particles into the particle-free fluid stream at a point along the rotating tubular section, whereby to produce a particle-laden fluid stream. This last-mentioned stream can then be used in combination with a cooperating nozzle arrangement for providing a rotating particle-laden fluid jet. In an actual working embodiment, the fluid stream is of sufficiently high pressure so that the abrasive jet can be used as a cutting jet.

  9. Vacuum rated flow controllers for inert gas ion engines

    NASA Technical Reports Server (NTRS)

    Pless, L. C.

    1987-01-01

    Electrical propulsion systems which use a gas as a propellant require a gas flowmeter/controller which is capable of operating in a vacuum environment. The presently available instruments in the required flow ranges are designed and calibrated for use at ambient pressure. These instruments operate by heating a small diameter tube through which the gas is flowing and then sensing the change in temperature along the length of the tube. This temperature change is a function of the flow rate and the gas heat capacity. When installed in a vacuum, the change in the external thermal characteristics cause the tube to overheat and the temperature sensors are then operating outside their calibrated range. In addition, the variation in heat capacity with temperature limit the accuracy obtainable. These problems and the work in progress to solve them are discussed.

  10. Age related flow rate nomograms in a normal pediatric population.

    PubMed

    Gaum, L D; Wese, F X; Liu, T P; Wong, A K; Hardy, B E; Churchill, B M

    1989-01-01

    Uroflow studies in a normal pediatric population were analysed statistically. Single studies for 511 subjects (272 boys and 239 girls) were reviewed. Nomograms relating peak flow to volume voided and age were established. An acceptable lower limit for peak flow was obtained from the data and a volume voided range was calculated so that both criteria could be used with 90% probability to define the normal voiding situation. The mean values of peak flow rate increased with volume voided in both sexes and also with age in the male population. Different sets of nomograms, which are necessary for daily clinical evaluation, are given. They define the normal values in the normal population. PMID:2763925

  11. Effect of mechanical abrasion on the viability, disruption and germination of spores of Bacillus subtilis

    PubMed Central

    Jones, C.A.; Padula, N.L.; Setlow, P.

    2005-01-01

    Aims To elucidate the factors influencing the sensitivity of Bacillus subtilis spores to killing and disruption by mechanical abrasion, and the mechanism of stimulation of spore germination by abrasion. Methods and Results Spores of B. subtilis strains were abraded by shaking with glass beads in liquid or the dry state, and spore killing, disruption and germination were determined. Dormant spores were more resistant to killing and disruption by abrasion than were growing cells or germinated spores. However, dormant spores of the wild-type strain with or without most coat proteins removed, spores of strains with mutations causing spore coat defects, spores lacking their large depot of dipicolinic acid (DPA) and spores with defects in the germination process exhibited essentially identical rates of killing and disruption by abrasion. When spores lacking all nutrient germinant receptors were enumerated by plating directly on nutrient medium, abrasion increased the plating efficiency of these spores before killing them. Spores lacking all nutrient receptors and either of the two redundant cortex-lytic enzymes behaved similarly in this regard, but the plating efficiency of spores lacking both cortex-lytic enzymes was not stimulated by abrasion. Conclusions Dormant spores are more resistant to killing and disruption by abrasion than are growing cells or germinated spores, and neither the complete coats nor DPA are important in spore resistance to such treatments. Germination is not essential for spore killing by abrasion, although abrasion can trigger spore germination by activation of either of the spore’s cortex-lytic enzymes. Significance and Importance This work provides new insight into the mechanisms of the killing, disruption and germination of spores by abrasion and makes the surprising finding that at least much of the spore coat is not important in spore resistance to abrasion. PMID:16313421

  12. A transport equation for reaction rate in turbulent flows

    NASA Astrophysics Data System (ADS)

    Sabelnikov, V. A.; Lipatnikov, A. N.; Chakraborty, N.; Nishiki, S.; Hasegawa, T.

    2016-08-01

    New transport equations for chemical reaction rate and its mean value in turbulent flows have been derived and analyzed. Local perturbations of the reaction zone by turbulent eddies are shown to play a pivotal role even for weakly turbulent flows. The mean-reaction-rate transport equation is shown to involve two unclosed dominant terms and a joint closure relation for the sum of these two terms is developed. Obtained analytical results and, in particular, the closure relation are supported by processing two widely recognized sets of data obtained from earlier direct numerical simulations of statistically planar 1D premixed flames associated with both weak large-scale and intense small-scale turbulence.

  13. Multi-rate flowing Wellbore electric conductivity logging method

    SciTech Connect

    Tsang, Chin-Fu; Doughty, Christine

    2003-04-22

    The flowing wellbore electric conductivity logging method involves the replacement of wellbore water by de-ionized or constant-salinity water, followed by constant pumping with rate Q, during which a series of fluid electric conductivity logs are taken. The logs can be analyzed to identify depth locations of inflow, and evaluate the transmissivity and electric conductivity (salinity) of the fluid at each inflow point. The present paper proposes the use of the method with two or more pumping rates. In particular it is recommended that the method be applied three times with pumping rates Q, Q /2, and 2Q. Then a combined analysis of the multi-rate data allows an efficient means of determining transmissivity and salinity values of all inflow points along a well with a confidence measure, as well as their inherent or far-field pressure heads. The method is illustrated by a practical example.

  14. Modeling the dissipation rate in rotating turbulent flows

    NASA Technical Reports Server (NTRS)

    Speziale, Charles G.; Raj, Rishi; Gatski, Thomas B.

    1990-01-01

    A variety of modifications to the modeled dissipation rate transport equation that have been proposed during the past two decades to account for rotational strains are examined. The models are subjected to two crucial test cases: the decay of isotropic turbulence in a rotating frame and homogeneous shear flow in a rotating frame. It is demonstrated that these modifications do not yield substantially improved predictions for these two test cases and in many instances give rise to unphysical behavior. An alternative proposal, based on the use of the tensor dissipation rate, is made for the development of improved models.

  15. Pressure-strain-rate events in homogeneous turbulent shear flow

    NASA Technical Reports Server (NTRS)

    Brasseur, James G.; Lee, Moon J.

    1988-01-01

    A detailed study of the intercomponent energy transfer processes by the pressure-strain-rate in homogeneous turbulent shear flow is presented. Probability density functions (pdf's) and contour plots of the rapid and slow pressure-strain-rate show that the energy transfer processes are extremely peaky, with high-magnitude events dominating low-magnitude fluctuations, as reflected by very high flatness factors of the pressure-strain-rate. A concept of the energy transfer class was applied to investigate details of the direction as well as magnitude of the energy transfer processes. In incompressible flow, six disjoint energy transfer classes exist. Examination of contours in instantaneous fields, pdf's and weighted pdf's of the pressure-strain-rate indicates that in the low magnitude regions all six classes play an important role, but in the high magnitude regions four classes of transfer processes, dominate. The contribution to the average slow pressure-strain-rate from the high magnitude fluctuations is only 50 percent or less. The relative significance of high and low magnitude transfer events is discussed.

  16. Decrease in the etch rate of polymers in the oxygen afterglow with increasing gas flow rate

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.; Wydeven, T.

    1988-01-01

    This paper reports the variation of the etch rate of polymers in the afterglow of a radio frequency discharge in oxygen as a function of total flow rate in the range 2-10 cu cm (STP)/min. The measurements were made at ambient temperature with the O(P-3) concentration held essentially constant. Results are reported on three polymers: cis-polybutadiene, a polybutadiene with 33 percent 1,2 double bonds, and a polybutadiene with 40 percent 1,2 double bonds. It has been observed that the etch rate of these polymers decreases significantly with increasing flow rate, strongly suggesting that the vapor-phase products of polymer degradation contribute to the degradation process.

  17. Interference well testing—variable fluid flow rate

    NASA Astrophysics Data System (ADS)

    Kutasov, I. M.; Eppelbaum, L. V.; Kagan, M.

    2008-03-01

    At present when conducting an interference well test a constant flow rate (at the 'active' well) is utilized and the type-curve matching technique (where only 2-3 values of pressure drops are matched) is used to estimate the porosity-total compressibility product and formation permeability. For oil and geothermal reservoirs with low formation permeability the duration of the test may require a long period of time and it can be difficult to maintain a constant flow rate. The qualitative term 'long' period of time means that (at a given distance between the 'active' and 'observational' well) more test time (for low permeability formations) is needed to obtain tangible pressure drops in the 'observational' well. In this study we present working equations which will allow us to process field data when the flow rate at the 'active' well is a function of time. The shut-in period is also considered. A new method of field data processing, where all measured pressure drops are utilized, is proposed. The suggested method allows us to make use of the statistical theory to obtain error estimates on the regression parameters. It is also shown that when high precision (resolution) pressure gauges are employed the pressure time derivative equations can be used for the determination of formation hydraulic diffusivity. An example is presented to demonstrate the data processing procedure.

  18. Sensitivity of Flow and Sediment Transport in Meandering Rivers to Scale Effects and Flow Rate

    SciTech Connect

    Shams, Mehrzad; Ahmadi, Goodarz; Smith, Duane H.

    2008-06-01

    Sensitivity of flow and sediment transport in a meandering river to variations in scaling and flow rate was studied. The FLUENT™ code was used for evaluating the river flow characteristics, including the mean velocity field and the Reynolds stress components, as well as for particle trajectory analysis. Particular attention was given to the sensitivity of the sedimentation patterns of different size particles in the river bend for various scales. Simulation studies were performed for both a model river and a physical river. The physical river was geometrically similar to the model river, with a scaling ratio of 1:100, but with identical Froude number. The flow and particle deposition patterns in the physical and model rivers were compared. It was shown that the mean flow quantities exhibit dynamic similarity, but the turbulence parameters and the particle sedimentation features in the physical river were different from the model. The secondary flows and particle transport patterns were also found to be sensitive to variation in the scale and flow rate.

  19. Computer Simulation of Stress-Strain State of Pipeline Section Affected by Abrasion Due to Mechanical Impurities

    NASA Astrophysics Data System (ADS)

    Burkov, P. V.; Afanas’ev, R. G.; Burkova, S. P.

    2016-04-01

    The paper presents the effect of abrasive wear of the pipeline section occurred due to mechanical impurities in the transported gas flow. The approaches to the detection of the maximum specific wear of the pipeline wall and the geometry of abrasion are the main problems of computer simulation described in this paper.

  20. Episodic fluid flow in the Nankai accretionary complex: Timescale, geochemistry, flow rates, and fluid budget

    USGS Publications Warehouse

    Saffer, D.M.; Bekins, B.A.

    1998-01-01

    Down-hole geochemical anomalies encountered in active accretionary systems can be used to constrain the timing, rates, and localization of fluid flow. Here we combine a coupled flow and solute transport model with a kinetic model for smectite dehydration to better understand and quantify fluid flow in the Nankai accretionary complex offshore of Japan. Compaction of sediments and clay dehydration provide fluid sources which drive the model flow system. We explicitly include the consolidation rate of underthrust sediments in our calculations to evaluate the impact that variations in this unknown quantity have on pressure and chloride distribution. Sensitivity analysis of steady state pressure solutions constrains bulk and flow conduit permeabilities. Steady state simulations with 30% smectite in the incoming sedimentary sequence result in minimum chloride concentrations at site 808 of 550 mM, but measured chlorinity is as low as 447 mM. We simulate the transient effects of hydrofracture or a strain event by assuming an instantaneous permeability increase of 3-4 orders of magnitude along a flow conduit (in this case the de??collement), using steady state results as initial conditions. Transient results with an increase in de??collement permeability from 10-16 m2 to 10-13 m2 and 20% smectite reproduce the observed chloride profile at site 808 after 80-160 kyr. Modeled chloride concentrations are highly sensitive to the consolidation rate of underthrust sediments, such that rapid compaction of underthrust material leads to increased freshening. Pressures within the de??collement during transient simulations rise rapidly to a significant fraction of lithostatic and remain high for at least 160 kyr, providing a mechanism for maintaining high permeability. Flow rates at the deformation front for transient simulations are in good agreement with direct measurements, but steady state flow rates are 2-3 orders of magnitude smaller than observed. Fluid budget calculations

  1. Abrasion-resistant coatings for plastic surfaces

    NASA Technical Reports Server (NTRS)

    Wydeven, T.; Hollahan, J. R.

    1976-01-01

    Optically clear composition of organosilicon compounds insulates plastic surfaces and protects them from abrasion. Plasma polymerization process produces superior uniformity and clarity than previous coating techniques.

  2. Measuring Black Smoker Fluid Flow Rates Using Image Correlation Velocimetry

    NASA Astrophysics Data System (ADS)

    Crone, T. J.; Wilcock, W. S.; McDuff, R. E.

    2006-12-01

    Motivated by a desire to find non-invasive methods for obtaining time-series measurements of fluid flow rates through mid-ocean ridge black smokers, we are developing an image-based velocimetry technique that will provide this information through the analysis of video sequences showing the turbulent structures of black smoker effluent jets. Our ultimate goal is to develop an autonomous seafloor instrument suitable for use with a cabled seafloor observatory that can provide extended time-series measurements of black smoker discharge rates with little user intervention. The method we are developing is based on the two-dimensional cross-correlation of an array of overlapping subimages from two sequential image frames within a sequence. For each pair of images this yields a two- dimensional representation of the instantaneous velocity field in the imaged flow. For each video sequence, the set of these "image velocity fields" from all image pairs is temporally averaged to yield a smoothed representation of the time-averaged image flow field. A transformation is then applied to convert the image flow fields into a relative discharge rate. We have developed a computational algorithm to implement this technique and have successfully applied it to video sequences collected in the late 1980s and early 1990s showing the discharge of black smokers in the Main Endeavour field of the Juan de Fuca Ridge over the course of weeks and months. We are able to resolve velocity fields that are qualitatively consistent with those predicted by plume theory from 5 seconds of video (150 image pairs), but it is difficult to calibrate or assess the precision of the technique with field data alone. In order to address these issues, as well as refine the computational algorithm, we have conducted laboratory simulations of black smoker jets with known discharge rates over a range of Reynolds numbers. We have recorded these simulations to obtain video image sequences that are similar to those

  3. Abrasive drill for resilient materials

    NASA Technical Reports Server (NTRS)

    Koch, A. J.

    1981-01-01

    Resilient materials normally present problem in obtaining accurate and uniform hole size and position. Tool is fabricated from stiff metal rod such as tungsten or carbon steel that has diameter slightly smaller than required hole. Piercing/centering point is ground on one end of rod. Rod is then plasma-sprayed (flame-sprayed) with suitable hard abrasive coating. High-speed, slow-feed operation of tool is necessary for accurate holes, and this can be done with drill press, hard drill, or similar machines.

  4. Quantitative characterization of agglomerate abrasion in a tumbling blender by using the Stokes number approach.

    PubMed

    Willemsz, Tofan A; Nguyen, Tien Thanh; Hooijmaijers, Ricardo; Frijlink, Henderik W; Vromans, Herman; van der Voort Maarschalk, Kees

    2013-03-01

    Removal of microcrystalline cellulose agglomerates in a dry-mixing system (lactose, 100 M) predominantly occurs via abrasion. The agglomerate abrasion rate potential is estimated by the Stokes abrasion (StAbr) number of the system. The StAbr number equals the ratio between the kinetic energy density of the moving powder bed and the work of fracture of the agglomerate. Basically, the StAbr number concept describes the blending condition of the dry-mixing system. The concept has been applied to investigate the relevance of process parameters on agglomerate abrasion in tumbling blenders. Here, process parameters such as blender rotational speed and relative fill volumes were investigated. In this study, the StAbr approach revealed a transition point between abrasion rate behaviors. Below this transition point, a blending condition exists where agglomerate abrasion is dominated by the kinetic energy density of the powder blend. Above this transition point, a blending condition exists where agglomerates show (undesirable) slow abrasion rates. In this situation, the blending condition is mainly determined by the high fill volume of the filler. PMID:23250711

  5. Oxygen Mass Flow Rate Generated for Monitoring Hydrogen Peroxide Stability

    NASA Technical Reports Server (NTRS)

    Ross, H. Richard

    2002-01-01

    Recent interest in propellants with non-toxic reaction products has led to a resurgence of interest in hydrogen peroxide for various propellant applications. Because peroxide is sensitive to contaminants, material interactions, stability and storage issues, monitoring decomposition rates is important. Stennis Space Center (SSC) uses thermocouples to monitor bulk fluid temperature (heat evolution) to determine reaction rates. Unfortunately, large temperature rises are required to offset the heat lost into the surrounding fluid. Also, tank penetration to accomodate a thermocouple can entail modification of a tank or line and act as a source of contamination. The paper evaluates a method for monitoring oxygen evolution as a means to determine peroxide stability. Oxygen generation is not only directly related to peroxide decomposition, but occurs immediately. Measuring peroxide temperature to monitor peroxide stability has significant limitations. The bulk decomposition of 1% / week in a large volume tank can produce in excess of 30 cc / min. This oxygen flow rate corresponds to an equivalent temperature rise of approximately 14 millidegrees C, which is difficult to measure reliably. Thus, if heat transfer were included, there would be no temperature rise. Temperature changes from the surrounding environment and heat lost to the peroxide will also mask potential problems. The use of oxygen flow measurements provides an ultra sensitive technique for monitoring reaction events and will provide an earlier indication of an abnormal decomposition when compared to measuring temperature rise.

  6. Decreased blood flow rate disrupts endothelial repair in vivo.

    PubMed Central

    Vyalov, S.; Langille, B. L.; Gotlieb, A. I.

    1996-01-01

    Both local hemodynamics and endothelial injury have been implicated in vascular disorders including bypass graft failure and atherogenesis, but little is known about the effect of local blood flow conditions on repair of endothelial injury. We decreased blood flow rates and shear stresses in common carotid arteries of rabbits by ligating the ipsilateral external carotid artery. After 24 hours, endothelial cells were less elongated, contained fewer central microfilament bundles, and showed less polarity of the centrosome toward the heart than endothelial cells in unmanipulated carotid arteries. To examine wound repair, we made narrow longitudinal intimal wounds at the time of flow reduction using a nylon monofilament device. In arteries with normal blood flows, endothelial cells at the edge of the wound initially spread and elongated in the direction of the wound. The dense peripheral band of actin was attenuated and central microfilaments became more prominent. Endothelial cells remained in close contact with their neighbors in the monolayer. The centrosome of cells adjacent to the wound was redistributed toward the wound side of the nucleus at 6 and 12 hours. Complete closure occurred by 24 hours, at which time the elongated endothelial cells covering the wound were organized in a herringbone pattern with their downstream ends at the center of the wound. With decreased flow and shear stress, the cells at the wound edge spread less than those in normal vessels at 12 hours after wounding and were randomly oriented and polygonal in shape. Also, re-endothelialization proceeded more slowly and there was a marked reduction of central microfilaments in cells at the wound edge. At 24 hours, the wounds were still open, the endothelial cells covering the central portion of the wound did not maintain intimate contact with their neighbors, and orientation of the centrosome toward the wound was reduced. We hypothesize that loss of cell-cell contact during repair at low flow

  7. Low-Flow-Rate Dry-Powder Feeder

    NASA Technical Reports Server (NTRS)

    Ramsey, Keith E.

    1994-01-01

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

  8. A numerical procedure for analysis of finite rate reacting flows

    NASA Technical Reports Server (NTRS)

    Shang, H. M.; Chen, Y. S.; Chen, Z. J.; Chen, C. P.; Wang, T. S.

    1993-01-01

    Combustion processes in rocket propulsion systems are characterized by the existence of multiple, vastly differing time and length scales, as well as flow-speeds at wide variation of Mach numbers. The chemical kinetics processes in the highly active reaction zone are characterized by much smaller scales compared to fluid convective and diffusive time scales. An operator splitting procedure for transient finite rate chemistry problems has been developed using a pressure based method, which can be applied to all speed flows without difficulties. The splitting of chemical kinetics terms formed the fluid-mechanical terms of the species equation ameliorated the difficulties associated with the disparate time scales and stiffness in the set of equations which describes highly exothermic combustion. A combined efficient ordinary differential equations (ODE) solver was used to integrate the effective chemical source terms over the residence time at each grid cell. One and two dimensional reacting flow situations were carried out to demonstrate and verify the current procedure. Different chemical kinetics with different degrees of nonlinearity have also been incorporated to test the robustness and generality of the proposed method.

  9. [Effects of carrier liquid and flow rate on the separation in gravitational field-flow fractionation].

    PubMed

    Guo, Shuang; Zhu, Chenqi; Gao-Yang, Yaya; Qiu, Bailing; Wu, Di; Liang, Qihui; He, Jiayuan; Han, Nanyin

    2016-02-01

    Gravitational field-flow fractionation is the simplest field-flow fractionation technique in terms of principle and operation. The earth' s gravity is its external field. Different sized particles are injected into a thin channel and carried by carrier fluid. The different velocities of the carrier liquid in different places results in a size-based separation. A gravitational field-flow fractionation (GrFFF) instrument was designed and constructed. Two kinds of polystyrene (PS) particles with different sizes (20 µm and 6 µm) were chosen as model particles. In this work, the separation of the sample was achieved by changing the concentration of NaN3, the percentage of mixed surfactant in the carrier liquid and the flow rate of carrier liquid. Six levels were set for each factor. The effects of these three factors on the retention ratio (R) and plate height (H) of the PS particles were investigated. It was found that R increased and H decreased with increasing particle size. On the other hand, the R and H increased with increasing flow rate. The R and H also increased with increasing NaN3 concentration. The reason was that the electrostatic repulsive force between the particles and the glass channel wall increased. The force allowed the samples approach closer to the channel wall. The results showed that the resolution and retention time can be improved by adjusting the experimental conditions. These results can provide important values to the further applications of GrFFF technique. PMID:27382718

  10. VARIABLE FIRING RATE OIL BURNER USING PULSE FUEL FLOW CONTROL.

    SciTech Connect

    KRISHNA,C.R.; BUTCHER,T.A.; KAMATH,B.R.

    2004-10-01

    problem is to develop a burner, which can operate at two firing rates, with the lower rate being significantly lower than 0.5 gallons per hour. This paper describes the initial results of adopting this approach through a pulsed flow nozzle. It has been shown that the concept of flow modulation with a small solenoid valve is feasible. Especially in the second configuration tested, where the Lee valve was integrated with the nozzle, reasonable modulation in flow of the order of 1.7 could be achieved. For this first prototype, the combustion performance is still not quite satisfactory. Improvements in operation, for example by providing a sharp and positive shut-off so that there is no flow under low pressures with consequent poor atomization could lead to better combustion performance. This could be achieved by using nozzles that have shut off or check valves for example. It is recommended that more work in cooperation with the valve manufacturer could produce a technically viable system. Marketability is of course a far more complex problem to be addressed once a technically viable product is available.

  11. Pervaporative irrigation: a flow rate driven by environmental conditions

    NASA Astrophysics Data System (ADS)

    Todman, L. C.; Mougros, C.; Ireson, A. M.; Butler, A. P.; Templeton, M. R.

    2012-04-01

    Pervaporative irrigation allows in-situ treatment of low quality water (e.g. saline water) whilst simultaneously distributing water throughout the soil. The system is also low energy, requiring only that a positive head of water is maintained in a supply tank. To irrigate using this method a pervaporative polymer membrane is formed into a pipe, buried in the soil and filled with water. Water is transported across the membrane by the process of pervaporation whilst the transport of contaminants is retarded, thus reducing the risk of soil degradation due to the use of low water quality. Uniquely these systems also inherently provide a feedback mechanism by which crops can affect the irrigation rate. Such a system has significant possibilities to provide an irrigation pipe from which water is only applied when required, hence reducing the volume of water used. However such systems are currently not fully understood and, to be implemented effectively, the behaviour of the membrane in different environmental conditions must be quantified. From experimental results this work has identified the significance of vapour flows in predicting the flux from the irrigation system in dry soils. In a 15cm layer of sand, the presence of a desiccant above the soil doubled the flux from the pipe, but more than 70% of this mass was adsorbed by the desiccant. Experiments also show that the flux into typical top soil was greater than into sand because of the greater capacity of the top soil for water adsorption. This adsorption maintained a lower humidity in the soil, hence providing a larger gradient across the irrigation membrane and inducing a higher flux. Although there is some evidence that seeds can absorb water from vapour flows the possibility that plants also do this has not yet been explored. This technology provides future opportunities to explore the interaction of plants both with vapour flows, and with a system where the irrigation rate is influenced by the crop uptake and

  12. compartment transfer rates in horizontal flow constructed wetlands

    NASA Astrophysics Data System (ADS)

    Maier, Uli; Oswald, Sascha; Thullner, Martin; Grathwohl, Peter

    2010-05-01

    A conceptual computer model has been constructed to simulate the compartment transfer rates in horizontal flow constructed wetlands. The model accounts for flow and transport in the variably saturated porous medium as well as biogeochemical change reactions. The most concentrated contaminants such as BTEX, MTBE and gasoline hydrocarbons and dissolved as well as mineral phase electron acceptors are considered. Also of major interest are reduced species with high oxygen demand such as ammonium. The influence of marsh plants on microbial activity, gas transport, water balance and contaminant fate in general is matter of current investigation. The constructed wetlands consist of a coarse sand or fine gravel porous medium. Marsh plants were introduced after installation, however, a number of control basins are operated unplanted. Water levels and through flow rates are adjusted to optimize the remediation efficiency. The system is likely to be neither reaction nor mixing limited, thus both, values of dispersivity and degradation kinetics may be crucial for remediation efficiency. Biogeochemical modelling is able to delineate in detail (i) the zonation of processes, (ii) temporal variation (breakthrough curves) and (iii) mass balance information. The contributions of biodegradation and volatilisation and the influence of plants (compartment transfer) can generally best be evaluated by the component's mass balance. More efficient mixing is expected in the wetlands with open water body which leads to both, more biodegradation and volatilisation. An important task is to quantify the role of plants and root systems for contaminant attenuation in constructed wetlands. The long term goal of investigation is to allow for predictions for the design of large scale compartment transfer wetlands that may be applied to remediate the site as a whole.

  13. Development of a flow rate monitoring method for the wearable ventricular assist device driver.

    PubMed

    Ohnuma, Kentaro; Homma, Akihiko; Sumikura, Hirohito; Tsukiya, Tomonori; Takewa, Yoshiaki; Mizuno, Toshihide; Mukaibayashi, Hiroshi; Kojima, Koichi; Katano, Kazuo; Taenaka, Yoshiyuki; Tatsumi, Eisuke

    2015-06-01

    Our research institute has been working on the development of a compact wearable drive unit for an extracorporeal ventricular assist device (VAD) with a pneumatically driven pump. A method for checking the pump blood flow on the side of the drive unit without modifying the existing blood pump and impairing the portability of it will be useful. In this study, to calculate the pump flow rate indirectly from measuring the flow rate of the driving air of the VAD air chamber, we conducted experiments using a mock circuit to investigate the correlation between the air flow rate and the pump flow rate as well as its accuracy and error factors. The pump flow rate was measured using an ultrasonic flow meter at the inflow and outflow tube, and the air flow was measured using a thermal mass flow meter at the driveline. Similarity in the instantaneous waveform was confirmed between the air flow rate in the driveline and the pump flow rate. Some limitations of this technique were indicated by consideration of the error factors. A significant correlation was found between the average pump flow rate in the ejecting direction and the average air flow rate in the ejecting direction (R2 = 0.704-0.856), and the air flow rate in the filling direction (R2 = 0.947-0.971). It was demonstrated that the average pump flow rate was estimated exactly in a wide range of drive conditions using the air flow of the filling phase. PMID:25500948

  14. Ceramic-bonded abrasive grinding tools

    DOEpatents

    Holcombe, Jr., Cressie E.; Gorin, Andrew H.; Seals, Roland D.

    1994-01-01

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  15. Ceramic-bonded abrasive grinding tools

    DOEpatents

    Holcombe, C.E. Jr.; Gorin, A.H.; Seals, R.D.

    1994-11-22

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  16. Ultrasonic Abrasive Removal Of EDM Recast

    NASA Technical Reports Server (NTRS)

    Mandel, Johnny L.; Jacobson, Marlowe S.

    1990-01-01

    Ultrasonic abrasive process removes layer of recast material generated during electrical-discharge machining (EDM) of damper pocket on turbine blade. Form-fitted tool vibrated ultrasonically in damper pocket from which material removed. Vibrations activate abrasive in pocket. Amount of material removed controlled precisely.

  17. Bendable Extension For Abrasive-Jet Cleaning

    NASA Technical Reports Server (NTRS)

    Mayer, Walter

    1989-01-01

    Hard-to-reach places cleaned more easily. Extension for abrasive-jet apparatus bent to provide controlled abrasive cleaning of walls in deep cavities or other hard-to-reach places. Designed for controlled removal of penetrant inspection dyes from inside castings, extension tube also used for such general grit-blasting work as removal of scratches.

  18. Development of digital flow control system for multi-channel variable-rate sprayers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Precision modulation of nozzle flow rates is a critical step for variable-rate spray applications in orchards and ornamental nurseries. An automatic flow rate control system activated with microprocessors and pulse width modulation (PWM) controlled solenoid valves was developed to control flow rates...

  19. Corneal abrasions associated with pepper spray exposure.

    PubMed

    Brown, L; Takeuchi, D; Challoner, K

    2000-05-01

    Pepper spray containing oleoresin capsicum is used by law enforcement and the public as a form of nonlethal deterrent. Stimulated by the identification of a case of a corneal abrasion associated with pepper spray exposure, a descriptive retrospective review of a physician-maintained log of patients presenting to a jail ward emergency area over a 3-year period was performed. The objective was to give some quantification to the frequency with which an emergency physician could expect to see corneal abrasions associated with pepper spray exposure. Of 100 cases of pepper spray exposure identified, seven patients had sustained corneal abrasions. We conclude that corneal abrasions are not rare events when patients are exposed to pepper spray and that fluorescein staining and slit lamp or Wood's lamp examination should be performed on all exposed patients in whom corneal abrasions cannot be excluded on clinical grounds. PMID:10830682

  20. High Resolution Laser Scanning Techniques for Rock Abrasion and Texture Analyses on Mars and Earth

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.; Razdan, A.; Greeley, R.; Laity, J. E.

    2004-01-01

    Aeolian abrasion is operative in many arid locations on Earth and is probably the dominant rock erosion process in the current Martian environment. Therefore, understanding the controlling parameters and rates of aeolian abrasion provides 1) insight into the stability of rocks on planetary surfaces and the environments under which the rocks abrade, and 2) a link between ventifact (a rock abraded by windblown particles) morphology and: a) abrasion conditions, b) possible ancient environments under which the rocks were abraded, and c) rock properties. promising and we plan further investigations in the wind tunnel and field. Our intent here is to discuss the basic technique, initial results, and upcoming plans.

  1. Abrasive wear by coal-fueled diesel engine and related particles

    SciTech Connect

    Ives, L.K.

    1992-09-01

    The development of commercially viable diesel engines that operate directly on pulverized coal-fuels will require solution to the problem of severe abrasive wear. The purpose of the work described in this report was to investigate the nature of the abrasive wear problem. Analytical studies were carried out to determine the characteristics of the coal-fuel and associated combustion particles responsible for abrasion. Laboratory pinon-disk wear tests were conducted on oil-particle mixtures to determine the relationship between wear rate and a number of different particle characteristics, contact parameters, specimen materials properties, and other relevant variables.

  2. Fluid flow meter for measuring the rate of fluid flow in a conduit

    NASA Technical Reports Server (NTRS)

    White, P. R. (Inventor)

    1986-01-01

    A tube fluid flow rate meter consists of a reservoir divided by flexible diaphragm into two separate isolated compartments. The incoming and outgoing tubes open into the compartments. The orifice is sized to allow maximum tube fluid flow. Opposing compression springs are secured within the two compartments on opposite sides of the orifice to maintain orifice position when the tube fluid pressure is zero. A tapered element is centered in, and extends through the orifice into the compartment, leaving an annular opening between the element and the perimeter of the oriface. The size varies as the diaphragm flexes with changes in the tube fluid pressure to change the fluid flow through the opening. The light source directs light upon the element which in turn scatters the light through the opening into the compartment. The light detector in the compartment senses the scattered light to generate a signal indicating the amount of fluid.

  3. Influence of Corrosion on the Abrasion of Cutter Steels Used in TBM Tunnelling

    NASA Astrophysics Data System (ADS)

    Espallargas, N.; Jakobsen, P. D.; Langmaack, L.; Macias, F. J.

    2015-01-01

    Abrasion on tunnel boring machine (TBM) cutters may be critical in terms of project duration and costs. Several researchers are currently studying the degradation of TBM cutter tools used for excavating hard rock, soft ground and loose soil. So far, the primary focus of this research has been directed towards abrasive wear. Abrasive wear is a very common process in TBM excavation, but with a view to the environment in which the tools are working, corrosion may also exert an influence. This paper presents a selection of techniques that can be used to evaluate the influence of corrosion on abrasion on TBM excavation tools. It also presents the influence of corrosion on abrasive wear for some initial tests, with constant steel and geomaterial and varying properties of the excavation fluids (soil conditioners, anti-abrasion additives and water). The results indicate that the chloride content in the water media greatly influences the amount of wear, providing evidence of the influence of corrosion on the abrasion of the cutting tools. The presence of conditioning additives tailored to specific rock or soil conditions reduces wear. However, when chloride is present in the water, the additives minimise wear rates but fail to suppress corrosion of the cutting tools.

  4. Flow rate calibration for absolute cell counting rationale and design.

    PubMed

    Walker, Clare; Barnett, David

    2006-05-01

    There is a need for absolute leukocyte enumeration in the clinical setting, and accurate, reliable (and affordable) technology to determine absolute leukocyte counts has been developed. Such technology includes single platform and dual platform approaches. Derivations of these counts commonly incorporate the addition of a known number of latex microsphere beads to a blood sample, although it has been suggested that the addition of beads to a sample may only be required to act as an internal quality control procedure for assessing the pipetting error. This unit provides the technical details for undertaking flow rate calibration that obviates the need to add reference beads to each sample. It is envisaged that this report will provide the basis for subsequent clinical evaluations of this novel approach. PMID:18770842

  5. Microstructure and abrasive wear in silicon nitride ceramics

    SciTech Connect

    Dogan, Cynthia P.; Hawk, Jeffrey A.

    2001-10-01

    It is well known that abrasive wear resistance is not strictly a materials property, but also depends upon the specific conditions of the wear environment. Nonetheless, characteristics of the ceramic microstructure do influence its hardness and fracture toughness and must, therefore, play an active role in determining howa ceramic will respond to the specific stress states imposed upon it by the wear environment. In this study, the ways in which composition and microstructure influence the abrasive wear behavior of six commercially-produced silicon nitride based ceramics are examined. Results indicate that microstructural parameters, such as matrix grain size and orientation, porosity, and grain boundary microstructure, and thermal expansion mismatch stresses created as the result of second phase formation, influence the wear rate through their effect on wear sheet formation and subsurface fracture. It is also noted that the potential impact of these variables on the wear rate may not be reflected in conventional fracture toughness measurements.

  6. Computational techniques for flows with finite-rate condensation

    NASA Technical Reports Server (NTRS)

    Candler, Graham V.

    1993-01-01

    A computational method to simulate the inviscid two-dimensional flow of a two-phase fluid was developed. This computational technique treats the gas phase and each of a prescribed number of particle sizes as separate fluids which are allowed to interact with one another. Thus, each particle-size class is allowed to move through the fluid at its own velocity at each point in the flow field. Mass, momentum, and energy are exchanged between each particle class and the gas phase. It is assumed that the particles do not collide with one another, so that there is no inter-particle exchange of momentum and energy. However, the particles are allowed to grow, and therefore, they may change from one size class to another. Appropriate rates of mass, momentum, and energy exchange between the gas and particle phases and between the different particle classes were developed. A numerical method was developed for use with this equation set. Several test cases were computed and show qualitative agreement with previous calculations.

  7. Emulsification in turbulent flow 2. Breakage rate constants.

    PubMed

    Vankova, Nina; Tcholakova, Slavka; Denkov, Nikolai D; Vulchev, Vassil D; Danner, Thomas

    2007-09-15

    Systematic experimental study of the effects of several factors on the breakage rate constant, k(BR), during emulsification in turbulent flow is performed. These factors are the drop size, interfacial tension, viscosity of the oil phase, and rate of energy dissipation in the flow. As starting oil-water premixes we use emulsions containing monodisperse oil drops, which have been generated by the method of membrane emulsification. By passing these premixes through a narrow-gap homogenizer, working in turbulent regime of emulsification, we study the evolution of the number concentration of the drops with given diameter, as a function of the emulsification time. The experimental data are analyzed by a kinetic scheme, which takes into account the generation of drops of a given size (as a result of breakage of larger drops) and their disappearance (as a result of their own breakage process). The experimental results for k(BR) are compared with theoretical expressions from the literature and their modifications. The results for all systems could be described reasonably well by an explicit expression, which is a product of: (a) the frequency of collisions between drops and turbulent eddies of similar size, and (b) the efficiency of drop breakage, which depends on the energy required for drop deformation. The drop deformation energy contains two contributions, originating from the drop surface extension and from the viscous dissipation inside the breaking drop. In the related subsequent paper, the size distribution of the daughter drops formed in the process of drop breakage is analyzed for the same experimental systems. PMID:17553511

  8. Characterization and dispersion of pollutant releases from the abrasive blasting of lead paint from steel bridges

    SciTech Connect

    Lee, M.; Rana, B.

    1999-07-01

    The characterization of airborne and spent material for abrasive blasting of steel paint was performed as part of the Environmental Impact Statement for Lead Paint Removal Operations on New York City Department of Transportation Bridges1. Laboratory tests were performed on painted steel components of the Williamsburg Bridge, to determine the sizes of particles typically released into the air as aerosol and onto the ground as bulk material, as a result of accidental releases from abrasive blasting operations. Two of the most commonly used abrasives for paint removal on steel structures, recyclable steel grit and expendable abrasives were subjected to the laboratory tests. The results of the tests were used to determine the percentage of existing paint and abrasive which becomes airborne and the resultant particle size distributions, which were employed in the air quality concentration and deposition modeling for the EIS. Particle size distributions of the airborne material indicated that the profiles of airborne lead and particulate matter have a mean particle size between 15 and 21 microns. Spent abrasives and paint chips that settle on the floor are larger in size with a mean diameter greater than 259 microns, although up to 6% of this material has a mean diameter less than 50 microns. The percentage of paint and expendable abrasives that become airborne as a result of abrasive blasting were estimated to be as high as 9.0 and 12.4%, respectively. Potential release rates were derived for total accumulation (duration of the project), annual, quarterly, 24-hour, and 1-hour time averaging periods for abrasives, lead, and other metals. Pollutant releases were simulated as individual sources at multiple release heights with the Environment Protection Agency's ISC3ST model for six representative bridges near potential places of public exposure.

  9. Controls on matrix flow, preferential flow and deep drainage rates in an alluvial Vertisol.

    NASA Astrophysics Data System (ADS)

    Arnold, Sven; Larsen, Joshua; Reading, Lucy; Finch, Warren; Bulovic, Nevenka; McIntyre, Neil

    2016-04-01

    Deep drainage is the process that describes water percolating from the land surface to a depth below the root zone where it may contribute to groundwater recharge. Quantitative estimation of deep drainage through Vertisols is challenging, largely due to the unknown relative contributions from: (i) flow through the soil matrix; and (ii) flow along preferential pathways in particular soil cracks, and how to model the transience of the relative contributions. The Condamine River Alluvium, a significant aquifer in semi-arid eastern Australia, is mostly covered by uniform dark cracking clays such as Black and Grey Vertisols. The aim of this study was to identify the environmental conditions (rainfall, antecedent soil moisture, etc) controlling matrix and preferential flow in selected Vertisol profiles at the time scale of individual rainfall events. Field experiments (including 16 probes recording soil moisture at one hour intervals across eight depths between 100 mm and 4000 mm) provide extensive soil moisture data, supplemented by weather station data collected at 15-minute intervals. In addition, laboratory experiments were used to infer the water retention curves. These data were used to (i) derive deep drainage rates using the zero-flux plane method, and (ii) calibrate a soil moisture balance model that represents both matrix and preferential flow. The model was used to estimate the parts of the vertical water flux attributed to soil matrix and preferential flow. High antecedent soil moisture was associated with low fluxes at shallow depths, however at deeper depths both low and high antecedent soil moisture were associated with larger fluxes. Further, both rainfall amount and intensity controlled the interplay between matrix and preferential flow. The results reveal new insights into deep drainage processes in Vertisols and provide the basis for developing a practical approach for deep drainage estimation.

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  11. 40 CFR 75.33 - Standard missing data procedures for SO2, NOX, and flow rate.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... SO2, NOX, and flow rate. 75.33 Section 75.33 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....33 Standard missing data procedures for SO2, NOX, and flow rate. (a) Following initial certification of the required SO2, NOX, and flow rate monitoring system(s) at a particular unit or stack...

  12. 40 CFR 75.33 - Standard missing data procedures for SO2, NOX, and flow rate.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SO2, NOX, and flow rate. 75.33 Section 75.33 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....33 Standard missing data procedures for SO2, NOX, and flow rate. (a) Following initial certification of the required SO2, NOX, and flow rate monitoring system(s) at a particular unit or stack...

  13. 40 CFR 75.33 - Standard missing data procedures for SO2, NOX, and flow rate.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SO2, NOX, and flow rate. 75.33 Section 75.33 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....33 Standard missing data procedures for SO2, NOX, and flow rate. (a) Following initial certification of the required SO2, NOX, and flow rate monitoring system(s) at a particular unit or stack...

  14. 40 CFR 75.33 - Standard missing data procedures for SO2, NOX, and flow rate.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SO2, NOX, and flow rate. 75.33 Section 75.33 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....33 Standard missing data procedures for SO2, NOX, and flow rate. (a) Following initial certification of the required SO2, NOX, and flow rate monitoring system(s) at a particular unit or stack...

  15. Study of coolant activation and dose rates with flow rate and power perturbations in pool-type research reactors

    SciTech Connect

    Mirza, N.M.; Mirza, S.M.; Ahmad, N. )

    1991-12-01

    This paper reports on a computer code using the multigroup diffusion theory based LEOPARD and ODMUG programs that has been developed to calculate the activity in the coolant leaving the core of a pool-type research reactor. Using this code, the dose rates at various locations along the coolant path with varying coolant flow rate and reactor power perturbations are determined. A flow rate decrease from 1000 to 145 m{sup 3}/h is considered. The results indicate that a flow rate decrease leads to an increase in the coolant outlet temperature, which affects the neutron group constants and hence the group fluxes. The activity in the coolant leaving the core increases with flow rate decrease. However, at the inlet of the holdup tank, the total dose rate first increases, then passes through a maximum at {approximately} 500 m{sup 3}/h, and finally decreases with flow rate decrease. The activity at the outlet of the holdup tank is mainly due to {sup 24}Na and {sup 56}Mn, and it increases by {approximately} 2% when the flow rate decreases from 1000 to 145 m{sup 3}/h. In an accidental power rise at constant flow rate, the activity in the coolant increases, and the dose rates at all the points along the coolant path show a slight nonlinear rise as the reactor power density increases.

  16. Unsteady flow characteristic of low-specific-speed centrifugal pump under different flow-rate conditions

    NASA Astrophysics Data System (ADS)

    Cui, Baoling; Chen, Desheng; Xu, Wenjing; Jin, Yingzi; Zhu, Zuchao

    2015-02-01

    To investigate the unsteady flow characteristics in centrifugal pump, the flow field in a low-specific-speed centrifugal pump with complex impeller is numerically simulated under different conditions. The RNG κ-ɛ turbulence model and sliding mesh are adopted during the process of computation. The results show that the interaction between impeller and volute results in the unstable flow of the fluid, which causes the uneven distribution of pressure fluctuations around the circumference of volute. Besides the main frequency and its multiple frequency of pressure fluctuations in the centrifugal pump, the frequency caused by the long blades of complex impeller also plays a dominant role in the low-frequency areas. Furthermore, there exists biggish fluctuation phenomenon near the tongue. The composition of static pressure fluctuations frequency on the volute wall and blade outlet is similar except that the fluctuation amplitude near the volute wall reduces. In general, the different flow rates mainly have influence on the amplitude of fluctuation frequency in the pump, while have little effect on the frequency composition.

  17. The abrasion and impact-abrasion behavior of austempered ductile irons

    SciTech Connect

    Hawk, Jeffrey A.; Dogan, Omer N.; Lerner, Y.S.

    1998-01-01

    Austempering of ductile irons has led to a new class of irons, Austempered Ductile Irons (ADIs), with improved mechanical strength and fracture toughness lacking in gray cast irons. Laboratory wear tests have been used to evaluate the abrasive and impact-abrasive wear behavior of a suite of ADIs. The use of high-stress, two-body abrasion, low-stress, three-body abrasion, and impact-abrasion tests provides a clear picture of the abrasive wear behavior of the ADIs and the mechanisms of material removal. When combined with hardness measurements, fracture toughness and a knowledge of the microstructure of the ADIs, the overall performance can be assessed relative to more wear resistant materials such as martensitic steels and high-chromium white cast irons

  18. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various abrasives... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Abrasive device and accessories. 872.6010...

  19. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various abrasives... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Abrasive device and accessories. 872.6010...

  20. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories. (a) Identification. An abrasive device and accessories is a device constructed of various abrasives... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Abrasive device and accessories. 872.6010...

  1. The Effect of Pleural Abrasion on the Treatment of Primary Spontaneous Pneumothorax: A Systematic Review of Randomized Controlled Trials

    PubMed Central

    Ming, Mo-yu; Cai, Shuang-qi; Chen, Yi-Qiang

    2015-01-01

    Background Pleural abrasion has been widely used to control the recurrence of primary spontaneous pneumothorax (PSP). However, controversy still exists regarding the advantages and disadvantages of pleural abrasion compared with other interventions in preventing the recurrence of PSP. Methods The PubMed, Embase, and Cochrane Central Register of Controlled Trials databases were searched up to December 15, 2014 to identify randomized controlled trials (RCTs) that compared the effects of pleural abrasion with those of other interventions in the treatment of PSP. The study outcomes included the PSP recurrence rate and the occurrence rate of adverse effects. Results Mechanical pleural abrasion and apical pleurectomy after thoracoscopic stapled bullectomy exhibited similarly persistent postoperative air leak occurrence rates (p = 0.978) and 1-year PSP recurrence rates (p = 0.821), whereas pleural abrasion led to reduced residual chest pain and discomfort (p = 0.001) and a smaller rate of hemothorax (p = 0.036) than did apical pleurectomy. However, the addition of minocycline pleurodesis to pleural abrasion did not reduce the pneumothorax recurrence rate compared with apical pleurectomy (3.8% for both procedures) but was associated with fewer complications. There was no statistical difference in the pneumothorax recurrence rate between mechanical pleural abrasion and chemical pleurodesis with minocycline on either an intention-to-treat basis (4 of 42 versus 0 of 42, p = 0.12; Fisher exact test) or after exclusions (2 of 40 versus 0 of 42, p = 0.24; Fisher exact test). Pleural abrasion plus minocycline pleurodesis also did not reduce the pneumothorax recurrence rate compared with pleural abrasion alone (p = 0.055). Moreover, pleural abrasion plus minocycline pleurodesis was associated with more intense acute chest pain. The postoperative overall recurrence rate in patients who underwent staple line coverage with absorbable cellulose mesh and fibrin glue was similar to that

  2. Dental Abrasion of Incisor caused by a Babies' Dummy Clip: A Case Report.

    PubMed

    Doğramacı, Esma J; Rossi-Fedele, Giampiero

    2015-09-01

    Tooth surface loss (TSL), the non-carious loss of tooth tissue, is considered pathological if the teeth involved experience sensitivity and pain, are functionally compromised or they detract from the patient's appearance. TSL is a common clinical finding in many patient groups, although differences between the primary and permanent dentition contribute to TSL occurring at a faster rate and with worse outcomes in the primary dentition. This case report presents localized abrasion and associated apical periodontitis affecting a single primary tooth in a 2-year-old infant following the misuse of a babies' dummy clip whilst teething. Abrasion is rare in the primary dentition. CPD/CLINICAL RELEVANCE: This article highlights an unusual presentation of dental abrasion affecting the primary dentition caused by a previously unreported foreign object; abrasion in this case was a side-effect of soothing the discomfort of teething. PMID:26630866

  3. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  4. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  5. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  6. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  7. 30 CFR 72.610 - Abrasive blasting.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed... mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as...

  8. Method and apparatus for controlling the flow rate of mercury in a flow system

    DOEpatents

    Grossman, Mark W.; Speer, Richard

    1991-01-01

    A method for increasing the mercury flow rate to a photochemical mercury enrichment utilizing an entrainment system comprises the steps of passing a carrier gas over a pool of mercury maintained at a first temperature T1, wherein the carrier gas entrains mercury vapor; passing said mercury vapor entrained carrier gas to a second temperature zone T2 having temperature less than T1 to condense said entrained mercury vapor, thereby producing a saturated Hg condition in the carrier gas; and passing said saturated Hg carrier gas to said photochemical enrichment reactor.

  9. A New Method for Flow Rate Measurement in Millimeter-Scale Pipes

    PubMed Central

    Ji, Haifeng; Gao, Xuemin; Wang, Baoliang; Huang, Zhiyao; Li, Haiqing

    2013-01-01

    Combining the Capacitively Coupled Contactless Conductivity Detection (C4D) technique and the principle of cross correlation flow measurement, a new method for flow rate measurement in millimeter-scale pipes was proposed. The research work included two parts. First, a new five-electrode C4D sensor was developed. Second, with two conductivity signals obtained by the developed sensor, the flow rate measurement was implemented by using the principle of cross correlation flow measurement. The experimental results showed that the proposed flow rate measurement method was effective, the developed five-electrode C4D sensor was successful, and the measurement accuracy was satisfactory. In five millimeter-scale pipes with different inner diameters of 0.5, 0.8, 1.8, 3.0 and 3.9 mm respectively, the maximum relative difference of the flow rate measurement between the reference flow rate and the measured flow rate was less than 5%. PMID:23353139

  10. The measurement of abrasive particles velocities in the process of abrasive water jet generation

    NASA Astrophysics Data System (ADS)

    Zeleňák, Michal; Foldyna, Josef; Říha, Zdeněk

    2014-08-01

    An optimization of the design of the abrasive cutting head using the numerical simulation requires gathering as much information about processes occurring in the cutting head as possible. Detailed knowledge of velocities of abrasive particles in the process of abrasive water jet generation is vital for the verification of the numerical model. A method of measurement of abrasive particles at the exit of focusing tube using the FPIV technique was proposed and preliminary tests are described in the paper. Results of analysis of measured velocity fields are presented in the paper.

  11. New iron-based SiC spherical composite magnetic abrasive for magnetic abrasive finishing

    NASA Astrophysics Data System (ADS)

    Zhang, Guixiang; Zhao, Yugang; Zhao, Dongbiao; Zuo, Dunwen; Yin, Fengshi

    2013-03-01

    SiC magnetic abrasive is used to polish surfaces of precise, complex parts which are hard, brittle and highly corrosion-resistant in magnetic abrasive finishing(MAF). Various techniques are employed to produce this magnetic abrasive, but few can meet production demands because they are usually time-consuming, complex with high cost, and the magnetic abrasives made by these techniques have irregular shape and low bonding strength that result in low processing efficiency and shorter service life. Therefore, an attempt is made by combining gas atomization and rapid solidification to fabricate a new iron-based SiC spherical composite magnetic abrasive. The experimental system to prepare this new magnetic abrasive is constructed according to the characteristics of gas atomization and rapid solidification process and the performance requirements of magnetic abrasive. The new iron-based SiC spherical composite magnetic abrasive is prepared successfully when the machining parameters and the composition proportion of the raw materials are controlled properly. Its morphology, microstructure, phase composition are characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD) analysis. The MAF tests on plate of mold steel S136 are carried out without grinding lubricant to assess the finishing performance and service life of this new SiC magnetic abrasive. The surface roughness( R a) of the plate worked is rapidly reduced to 0.051 μm from an initial value of 0.372 μm within 5 min. The MAF test is carried on to find that the service life of this new SiC magnetic abrasive reaches to 155 min. The results indicate that this process presented is feasible to prepare the new SiC magnetic abrasive; and compared with previous magnetic abrasives, the new SiC spherical composite magnetic abrasive has excellent finishing performance, high processing efficiency and longer service life. The presented method to fabricate magnetic abrasive through gas atomization and rapid

  12. Flow rate decline of steam wells in fractured geothermal reservoirs

    SciTech Connect

    Bodvarsson, G.S.; Witherspoon, P.A.

    1985-01-01

    Decline curves are commonly used at The Geysers geothermal field to assess the generating capacity of a producing lease. It is generally assumed that wells will initially be drilled using 40-acre (400 m) spacing, with infill drilling used later to provide additional producing wells as needed. It is commonly believed that the final well spacing should not be less than 10 acres (200 m). Decline curves are used with this approach to estimate the number of make-up wells during a project lifetime (up to 30 years), as well as the appropriate plant size (MWe). A rather simple two-dimensional model was used to investigate the factors that control flow rate decline in steam wells. The effects of parameters such as fracture spacing and permeability are considered, as well as the effects of permeability, porosity and initial liquid saturation in the rock matrix. Also, the conventional P/z method that is commonly used in analyzing gas well production is investigated in terms of its applicability to fractured vapor dominated systems.

  13. Influence of the Flow Rate of Oxidising Atmosphere on the Flame Spread Rate on the Surface of Organic Setlled Dust

    NASA Astrophysics Data System (ADS)

    Martinka, Jozef; Balog, Karol; Hrušovský, Ivan; Valentová, Veronika

    2013-01-01

    The presented paper deals with determining the influence of the flow rate of oxidising atmosphere on the flame spread along the surface of the organic settled dust layer. We determined the rate of the flame spread on the surface of the organic settled dust layer (whole grain rye and spelt flour) with absolute moisture of 10 % wt., for the flow rates of oxidising atmosphere 1, 3, 5 and 10 cm/s. Pure oxygen was used as an oxidising atmosphere. The obtained results suggest that there exists a power relationship of the flame spread rate along the surface of organic settled dust layer to the flow rate of the oxidising mixture. The method described is suitable for the relative comparison of the organic settled dust layer from the point of its ability to spread the flame and the influence of the air flow rate on this process.

  14. The effect of temperature and flow rate on aluminum etch rates in RF plasmas

    SciTech Connect

    Danner, D.A.; Hess, D.W.

    1986-01-01

    The effect of sample temperature and etch gas flow rate on the etching of aluminum in BCl/sub 3//Cl/sub 2/ and CCl/sub 4//Cl/sub 2/ mixtures in a parallel-plate plasma etcher was investigated. Through the use of a thermally conductive epoxy to ensure good heat-transfer, sample heating due to exothermic chemical reactions and plasma heating was found to result in a temperature difference of more than 100/sup 0/C between bonded and unbonded samples. Thus, considerable increases in etch rate were observed for the unbonded samples. Etch nonuniformities during both the inhibition period and metal etching were studied, using different plasma conditions and a nozzle to deliver chlorine directly to the aluminum surface. Oxide etching depended upon ion flux and/or energy and upon the concentration of BCl/sub X/ or CCl/sub X/ species, while Cl/sub 2/ concentration at the sample surface determined the relative aluminum etch rates across the aluminum sample.

  15. Volumetric flow rate comparisons for water and product on pasteurization systems.

    PubMed

    Schlesser, J E; Stroup, W H; McKinstry, J A

    1994-04-01

    A flow calibration tube system was assembled to determine the volumetric flow rates for water and various dairy products through a holding tube, using three different flow promotion methods. With the homogenizer, the volumetric flow rates of water and reconstituted skim milk were within 1.5% of each other. With the positive displacement pump, the flow rate for reconstituted skim milk increased compared with that for water as the pressure increased or temperature decreased. The largest increase in flow rate was at 310-kPa gauge and 20 degrees C. On a magnetic flow meter system, the volumetric flow rates of water and reconstituted skim milk were within .5% of the flow rate measured from the volume collected in a calibrated tank. The flow rate of whole milk was similar to that of skim milk on the three flow promoters evaluated. Ice milk mix increased the flow rate of the positive displacement pump, but not the homogenizer and magnetic flow meter system. PMID:8201053

  16. Nonintrusive Flow Rate Determination Through Space Shuttle Water Coolant Loop Floodlight Coldplate

    NASA Technical Reports Server (NTRS)

    Werlink, Rudolph; Johnson, Harry; Margasahayam, Ravi

    1997-01-01

    Using a Nonintrusive Flow Measurement System (NFMS), the flow rates through the Space Shuttle water coolant coldplate were determined. The objective of this in situ flow measurement was to prove or disprove a potential block inside the affected coldplate had contributed to a reduced flow rate and the subsequent ice formation on the Space Shuttle Discovery. Flow through the coldplate was originally calculated to be 35 to 38 pounds per hour. This application of ultrasonic technology advanced the envelope of flow measurements through use of 1/4-inch-diameter tubing, which resulted in extremely low flow velocities (5 to 30 pounds per hour). In situ measurements on the orbiters Discovery and Atlantis indicated both vehicles, on the average, experienced similar flow rates through the coldplate (around 25 pounds per hour), but lower rates than the designed flow. Based on the noninvasive checks, further invasive troubleshooting was eliminated. Permanent monitoring using the NFMS was recommended.

  17. [Synchonization of the blood flow rate in arterial with the changing rate of space of blood pressure with time].

    PubMed

    Zhang, Shenghua; Qin, Renjia

    2012-10-01

    In physiology-related books, there are many relationship curves about blood flow rate in arteries and blood pressure changes with time, but there are not much explanation about such relationship. This is the very the question that the present article tries to answer. We clarified the relations between blood flow rate and blood pressure gradient using the experimental curves as the basis, using Poiseuille Law and relative knowledge of phisics and mathematics, and using analysis and reasoning. Based on the study, it can be concluded that in every course of cardiac cycle, the blood flow rate of any section in artery blood vessel is roughly synchronized with changing rate of space and time of the blood pressure, but blood flow rate is not synchronized with blood pressure. PMID:23198422

  18. Abrasive wear of advanced structural materials

    NASA Astrophysics Data System (ADS)

    Lee, Gun-Young

    Wear of advanced structural materials, namely composites and ceramics, in abrasion has been examined in the present study. A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile) matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material. The size of this non-contributing portion of reinforcement is estimated by modeling three primary wear mechanisms, specifically plowing, cracking at the matrix/reinforcement interface or in the reinforcement, and particle removal. Critical variables describing the role of the reinforcement, such as the relative size, fracture toughness, and the nature of the matrix/reinforcement interface, are characterized by a single contribution coefficient, C. Predictions are compared with the results of experimental two-body (pin-on-drum) abrasive wear tests performed on a model aluminum particulate-reinforced epoxy-matrix composite material. In addition, the effects of post heat-treatment on the wear behavior of toughened silicon carbide (ABC-SiC) are investigated by characterizing the role of the microstructures introduced during the post annealing processes. When the annealing temperature is above 1300°C, an aluminum rich secondary phase (nano-precipitate) forms and grows inside the SiC grains. This toughened silicon carbide (ABC-SiC), annealed at temperatures ranging from 0 to 1600°C, is subjected to two- and three-body abrasions with different sizes of abrasives (3˜70 mum). The test results exhibit that the effect of nano-precipitates on wear resistance of post-annealed ABC-SiC is restricted to the abrasion with fine abrasives (3 mum), since nano-precipitates, in the range from 4 nm at 1300°C to 25 nm at 1600°C, are comparable in dimension

  19. Air abrasion: an old technology reborn.

    PubMed

    Berry, E A; Eakle, W S; Summitt, J B

    1999-08-01

    Recently, air abrasion has experienced a rebirth in restorative dentistry. Originally developed in the late 1940s, the principle of air abrasion is the imparting of kinetic energy to tiny aluminum oxide particles that are projected by a stream of compressed air or gas and expelled from a small nozzle. The force generated by the relatively hard particles striking a relatively hard surface is sufficient to cut into that surface. In the last decade, more than a dozen models of air abrasion units have been introduced into the marketplace and more are on the way. Manufacturers have developed air abrasion instruments that offer a broad range of features, from small table-top units to self-contained systems with compressors, vacuums, and curing lights. The costs range dramatically--from $1,000 to $20,000 or more--depending on the complexity of the features and attachments. Manufacturers make a variety of claims to support the value of this technology to the practicing dentist. A term often used to describe one of the benefits of air abrasion is microdentistry. The claim is that smaller, less invasive tooth preparations may be accomplished using air abrasion than with a traditional bur and air turbine. This may be true in some instances, but it would certainly depend on the operator's experience and ability to visually discern fine detail. Other claims about air abrasion are that it can be used to cut into tooth structure without local anesthesia and that it should be used on all stained grooves or fissures to determine if incipient carious lesions are present. Despite the limited number of clinical studies, the popularity of air abrasion continues to grow. To gain additional insight about these claims and to see what might be on the horizon for this technology, I spoke with three highly respected educators who are recognized for their expertise in air abrasion. What they said should give the reader a better understanding of how air abrasion might augment restorative

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

    ERIC Educational Resources Information Center

    FOGARTY, WILLIAM J.; REEDER, MILTON E.

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

  1. A methodology to reduce uncertainties in the high-flow portion of a rating curve

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flow monitoring at watershed scale relies on the establishment of a rating curve that describes the relationship between stage and flow and is developed from actual flow measurements at various stages. Measurement errors increase with out-of-bank flow conditions because of safety concerns and diffic...

  2. Effect of flow rate on environmental variables and phytoplankton dynamics: results from field enclosures

    NASA Astrophysics Data System (ADS)

    Zhang, Haiping; Chen, Ruihong; Li, Feipeng; Chen, Ling

    2015-03-01

    To investigate the effects of flow rate on phytoplankton dynamics and related environment variables, a set of enclosure experiments with different flow rates were conducted in an artificial lake. We monitored nutrients, temperature, dissolved oxygen, pH, conductivity, turbidity, chlorophyll- a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s, which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light, resulting in a dramatic shift in phytoplankton composition, from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However, flow rate significantly enhanced the inter-relationships among environmental variables, in particular by inducing higher water turbidity and vegetative reproduction of periphyton ( Spirogyra). These changes were accompanied by a decrease in underwater light intensity, which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist, because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.

  3. Preparation of Fe-doped colloidal SiO(2) abrasives and their chemical mechanical polishing behavior on sapphire substrates.

    PubMed

    Lei, Hong; Gu, Qian; Chen, Ruling; Wang, Zhanyong

    2015-08-20

    Abrasives are one of key influencing factors on surface quality during chemical mechanical polishing (CMP). Silica sol, a widely used abrasive in CMP slurries for sapphire substrates, often causes lower material removal rate (MRRs). In the present paper, Fe-doped colloidal SiO2 composite abrasives were prepared by a seed-induced growth method in order to improve the MRR of sapphire substrates. The CMP performance of Fe-doped colloidal SiO2 abrasives on sapphire substrates was investigated using UNIPOL-1502 CMP equipment. Experimental results indicate that the Fe-doped colloidal SiO2 composite abrasives exhibit lower surface roughness and higher MRR than pure colloidal SiO2 abrasives for sapphire substrates under the same testing conditions. Furthermore, the acting mechanism of Fe-doped colloidal SiO2 composite abrasives in sapphire CMP was analyzed by x-ray photoelectron spectroscopy. Analytical results show that the Fe in the composite abrasives can react with the sapphire substrates to form aluminum ferrite (AlFeO3) during CMP, which promotes the chemical effect in CMP and leads to improvement of MRR. PMID:26368752

  4. Eruption rate, area, and length relationships for some Hawaiian lava flows

    NASA Technical Reports Server (NTRS)

    Pieri, David C.; Baloga, Stephen M.

    1986-01-01

    The relationships between the morphological parameters of lava flows and the process parameters of lava composition, eruption rate, and eruption temperature were investigated using literature data on Hawaiian lava flows. Two simple models for lava flow heat loss by Stefan-Boltzmann radiation were employed to derive eruption rate versus planimetric area relationship. For the Hawaiian basaltic flows, the eruption rate is highly correlated with the planimetric area. Moreover, this observed correlation is superior to those from other obvious combinations of eruption rate and flow dimensions. The correlations obtained on the basis of the two theoretical models, suggest that the surface of the Hawaiian flows radiates at an effective temperature much less than the inner parts of the flowing lava, which is in agreement with field observations. The data also indicate that the eruption rate versus planimetric area correlations can be markedly degraded when data from different vents, volcanoes, and epochs are combined.

  5. An electronic flow control system for a variable-rate tree sprayer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Precise modulation of nozzle flow rates is a critical measure to achieve variable-rate spray applications. An electronic flow rate control system accommodating with microprocessors and pulse width modulation (PWM) controlled solenoid valves was designed to manipulate the output of spray nozzles inde...

  6. Towards Multiphase Periodic Boundary Conditions with Flow Rate Constraint

    NASA Astrophysics Data System (ADS)

    Sawko, Robert; Thompson, Chris P.

    2011-09-01

    This paper presents the development of a solver for a two-phase, stratified flow with periodic boundary conditions. Governing equations are supplemented with a specification of constant mass fluxes for each phase. The method allows an estimate steady state phase fraction and pressure drop in the streamwise direction. The analytical solution for two-phase laminar flow is presented and serves as a validation of the numerical technique. For turbulent conditions, Reynolds-Averaged Navier-Stokes equations are employed and closed with a two-equation model. Experimental data is taken as a reference for the purpose of validation. In both flow conditions the method delivers accurate results although in the case of turbulent flow it requires the specification of interfacial viscosity showing that a direct generalisation of two-equation model is unsatisfactory. Further research avenues are outlined.

  7. Tracheal Mucus Flow Rates in Experimental Bronchitis in Rats

    PubMed Central

    Lightowler, Norah M.; Williams, J. R. B.

    1969-01-01

    The flow of mucus in the trachea of rats previously exposed to an atmosphere of SO2 in air was measured and correlated with the histological changes in the trachea, bronchi and lungs. Reduction in the speed of mucus flow in the exposed trachea was found with increasing severity of bronchopulmonary changes. ImagesFigs. 9-12Figs. 6-7Figs. 2-5 PMID:5772066

  8. Abrasion resistance of medical glove materials.

    PubMed

    Walsh, Donna L; Schwerin, Matthew R; Kisielewski, Richard W; Kotz, Richard M; Chaput, Maria P; Varney, George W; To, Theresa M

    2004-01-15

    Due to the increasing demand for nonlatex medical gloves in the health-care community, there is a need to assess the durability of alternative glove materials. This study examines durability characteristics of various glove materials by abrasion resistance testing. Natural rubber latex (latex), polyvinyl chloride (vinyl), acrylonitrile butadiene (nitrile), polychloroprene (neoprene), and a styrene-ethylene/butylene-styrene block copolymer (SEBS) were tested. All test specimens, with the exception of the vinyl, were obtained from surgical gloves. Unaged out-of-the-box specimens as well as those subjected to various degrees of artificial aging were included in the study. After the abrasion sequence, the barrier integrity of the material was assessed through the use of a static leak test. Other traditional tests performed on these materials were viral penetration to validate the abrasion data and tear testing for comparative purposes. The results indicate that specific glove-material performance is dependent upon the particular test under consideration. Most notably, abrasion, even in controlled nonsevere conditions, may compromise to varying degrees the barrier integrity of latex, vinyl, SEBS, nitrile, and neoprene glove materials. However, as evidenced by the results of testing three brands of neoprene gloves, the abrasion resistance of any one glove material may be significantly affected by variations in production processes. PMID:14689500

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  10. Temperature and flow rate effects on mass median diameters of thermally generated malathion and naled fogs.

    PubMed

    Brown, J R; Chew, V; Melson, R O

    1993-06-01

    The effects of temperature and flow rate on mass median diameters (mmds) of thermally generated aerosol clouds were studied. Number 2 fuel oil alone, undiluted and diluted malathion 91, and undiluted naled were examined. There was a significant flow rate x temperature interaction on the mmds of diluted malathion fogs: i.e., differences among flow rates depended on temperature and vice versa. PMID:8350082

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

    PubMed

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

    2015-02-01

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

  12. Numerical investigation and thermodynamic analysis of the effect of electrolyte flow rate on performance of all vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Khazaeli, Ali; Vatani, Ali; Tahouni, Nassim; Panjeshahi, Mohammad Hassan

    2015-10-01

    In flow batteries, electrolyte flow rate plays a crucial role on the minimizing mass transfer polarization which is at the compensation of higher pressure drop. In this work, a two-dimensional numerical method is applied to investigate the effect of electrolyte flow rate on cell voltage, maximum depth of discharge and pressure drop a six-cell stack of VRFB. The results show that during the discharge process, increasing electrolyte flow rate can raise the voltage of each cell up to 50 mV on average. Moreover, the maximum depth of discharge dramatically increases with electrolyte flow rate. On the other hand, the pressure drop also positively correlates with electrolyte flow rate. In order to investigate all these effects simultaneously, average energy and exergy efficiencies are introduced in this study for the transient process of VRFB. These efficiencies give insight into choosing an appropriate strategy for the electrolyte flow rate. Finally, the energy efficiency of electricity storage using VRFB is investigated and compared with other energy storage systems. The results illustrate that this kind of battery has at least 61% storage efficiency based on the second law of thermodynamics, which is considerably higher than that of their counterparts.

  13. Field measurements of incision rates following bedrock exposure: Implications for process controls on the long profiles of valleys cut by rivers and debris flows

    USGS Publications Warehouse

    Stock, Jonathan D.; Montgomery, David R.; Collins, Brian D.; Dietrich, William E.; Sklar, Leonard

    2005-01-01

    Until recently, published rates of incision of bedrock valleys came from indirect dating of incised surfaces. A small but growing literature based on direct measurement reports short-term bedrock lowering at geologically unsustainable rates. We report observations of bedrock lowering from erosion pins monitored over 1–7 yr in 10 valleys that cut indurated volcanic and sedimentary rocks in Washington, Oregon, California, and Taiwan. Most of these channels have historically been stripped of sediment. Their bedrock is exposed to bed-load abrasion, plucking, and seasonal wetting and drying that comminutes hard, intact rock into plates or equant fragments that are removed by higher flows. Consequent incision rates are proportional to the square of rock tensile strength, in agreement with experimental results of others. Measured rates up to centimeters per year far exceed regional long-term erosion-rate estimates, even for apparently minor sediment-transport rates. Cultural artifacts on adjoining strath terraces in Washington and Taiwan indicate at least several decades of lowering at these extreme rates. Lacking sediment cover, lithologies at these sites lower at rates that far exceed long-term rock-uplift rates. This rate disparity makes it unlikely that the long profiles of these rivers are directly adjusted to either bedrock hardness or rock-uplift rate in the manner predicted by the stream power law, despite the observation that their profiles are well fit by power-law plots of drainage area vs. slope. We hypothesize that the threshold of motion of a thin sediment mantle, rather than bedrock hardness or rock-uplift rate, controls channel slope in weak bedrock lithologies with tensile strengths below ∼3–5 MPa. To illustrate this hypothesis and to provide an alternative interpretation for power-law plots of area vs. slope, we combine Shields' threshold transport concept with measured hydraulic relationships and downstream fining rates. In contrast to fluvial

  14. An investigation into magnetic electrolytic abrasive turning

    NASA Astrophysics Data System (ADS)

    Mahdy, M. A. M.; Ismaeial, A. L.; Aly, F. F.

    2013-07-01

    The magnetic electrolytic abrasive turning (MEAT) process as a non-traditional machining is used to obtain surface finishing like mirror. MEAT provides one of the best alternatives for producing complex shapes with good finish in advanced materials used in aircraft and aerospace industries. The improvement of machining accuracy of MEAT continues to be a major challenge for modern industry. MEAT is a hybrid machining which combines two or more processes to remove material. The present research focuses on the development of precision electrochemical turning (ECT) under the effects of magnetic field and abrasives. The effect of magnetic flux density, electrochemical conditions and abrasive parameters on finishing efficiency and surface roughness are investigated. An empirical relationship is deduced.

  15. Effects of mean flow on duct mode optimum suppression rates

    NASA Technical Reports Server (NTRS)

    Kraft, R. E.; Wells, W. R.

    1976-01-01

    The nature of the solution to the convected acoustic wave equation and associated boundary conditions for rectangular ducts containing uniform mean flow is examined in terms of the complex mapping between the wall admittance and characteristic mode eigenvalues. It is shown that the Cremer optimum suppression criteria must be modified to account for the effects of flow below certain critical values of the nondimensional frequency parameter of duct height divided by sound wavelength. The implications of these results on the design of low frequency suppressors are considered.

  16. Flow in a mechanical bileaflet heart valve at laminar and near-peak systole flow rates: CFD simulations and experiments.

    PubMed

    Ge, Liang; Leo, Hwa-Liang; Sotiropoulos, Fotis; Yoganathan, Ajit P

    2005-10-01

    Time-accurate, fully 3D numerical simulations and particle image velocity laboratory experiments are carried out for flow through a fully open bileaflet mechanical heart valve under steady (nonpulsatile) inflow conditions. Flows at two different Reynolds numbers, one in the laminar regime and the other turbulent (near-peak systole flow rate), are investigated. A direct numerical simulation is carried out for the laminar flow case while the turbulent flow is investigated with two different unsteady statistical turbulence modeling approaches, unsteady Reynolds-averaged Navier-Stokes (URANS) and detached-eddy simulation (DES) approach. For both the laminar and turbulent cases the computed mean velocity profiles are in good overall agreement with the measurements. For the turbulent simulations, however, the comparisons with the measurements demonstrate clearly the superiority of the DES approach and underscore its potential as a powerful modeling tool of cardiovascular flows at physiological conditions. The study reveals numerous previously unknown features of the flow. PMID:16248308

  17. Corneal Abrasions and Corneal Foreign Bodies.

    PubMed

    Ahmed, Faheem; House, Robert James; Feldman, Brad Hal

    2015-09-01

    Corneal abrasions and corneal foreign bodies are frequently encountered ophthalmological injuries that are commonly diagnosed and managed by primary care physicians. The clinical course of a corneal epithelial defect can range from a relatively benign self-healing abrasion to a potentially sight-threatening complication such as a corneal ulcer, recurrent erosion, or traumatic iritis. A detailed clinical history regarding risk factors and exposure, along with a thorough slit lamp examination with fluorescein dye are essential for proper diagnosis and treatment, as well as to rule out penetrating globe injuries. Referral to an ophthalmologist is recommended in difficult cases or if other injuries are suspected. PMID:26319343

  18. Friction and abrasion of elastomeric materials

    NASA Technical Reports Server (NTRS)

    Gent, A. N.

    1975-01-01

    An abrasion apparatus is described. Experimental measurements are reported for four representative elastomeric materials, including a typical high-quality tire tread material and a possible replacement material for aircraft tire treads based on transpolypentenamer (TPPR). Measurements are carried out at different levels of frictional work input, corresponding to different severities of wear, and at both ambient temperature and at 100 C. Results indicate the marked superiority in abrasion resistance of the material based on TPPR, especially at 100 C, in comparison with the other materials examined.

  19. Long arc stabilities with various arc gas flow rates

    NASA Astrophysics Data System (ADS)

    Maruyama, K.; Takeda, K.; Sugimoto, M.; Noguchi, Y.

    2014-11-01

    A new arc torch for use in magnetically driven arc device was developed with a commercially available TIG welding arc torch. The torch has a water-cooling system to the torch nozzle and has a nozzle nut to supply a swirling-free plasma gas flow. Its endurance against arc thermal load is examined. Features of its generated arc are investigated.

  20. Sliding-gate valve for use with abrasive materials

    DOEpatents

    Ayers, Jr., William J.; Carter, Charles R.; Griffith, Richard A.; Loomis, Richard B.; Notestein, John E.

    1985-01-01

    The invention is a flow and pressure-sealing valve for use with abrasive solids. The valve embodies special features which provide for long, reliable operating lifetimes in solids-handling service. The valve includes upper and lower transversely slidable gates, contained in separate chambers. The upper gate provides a solids-flow control function, whereas the lower gate provides a pressure-sealing function. The lower gate is supported by means for (a) lifting that gate into sealing engagement with its seat when the gate is in its open and closed positions and (b) lowering the gate out of contact with its seat to permit abrasion-free transit of the gate between its open and closed positions. When closed, the upper gate isolates the lower gate from the solids. Because of this shielding action, the sealing surface of the lower gate is not exposed to solids during transit or when it is being lifted or lowered. The chamber containing the lower gate normally is pressurized slightly, and a sweep gas is directed inwardly across the lower-gate sealing surface during the vertical translation of the gate.

  1. Estimation of the velocities and discharge rates of groundwater flows by helium and tritium distributions

    SciTech Connect

    Ivanov, V.V.; Antonenko, E.F.; Obukhova, S.N.

    1995-11-01

    Modeling is used to show that bends in the curves of groundwater flows and confluence of different-age flows demonstrate themselves in spatial variability in concentration fields of {sup 4}He, {sup 3}H, and {sup 14}C isotopes. The results are used to reveal typical flows in a section of Switzerland and to estimate their velocities and discharge rates.

  2. Weldability of an abrasion-resistant steel

    SciTech Connect

    Adonyi, Y.; Domis, W.F.; Chen, C.C.

    1995-12-31

    The welding performance of a low-carbon-equivalent, abrasion-resistant steel newly developed for the mining industry was studied using a combination of simulative and actual weldability tests. The susceptibility to hydrogen-induced cracking in the weld-metal and heat-affected zones (HAZ), as well as the potential loss of strength and toughness in the HAZ, were evaluated. Simulative testing included the use of the Gleeble 1500 thermomechanical simulator to produce single and multiple-pass weld HAZ microstructures on CVN-size specimens. The effects of heat input, interpass temperature, and post-weld heat treatment (PWHT) on the HAZ microstructure and properties were determined. Additionally, a computer software was used to predict theoretical HAZ hardnesses and volume fraction of phases as a function of cooling rates. The actual welding tests included the Gapped Bead-on-Plate and the Y-groove tests to determine the weld-metal and HAZ susceptibility to hydrogen-induced cracking. Three heat inputs, two diffusible hydrogen and two weld-metal yield-strength levels were used for the actual welding stage. Good correlation was found between microstructure predictions, physical simulations, and actual weld testing results. The new steel was found to be highly weldable because of the low preheat required to avoid HAZ hydrogen induced cracking. All aspects of weld-metal and HAZ cracking behavior had to be addressed for a complete weldability characterization. It was also found that use of excessive heat inputs and PWHT should be avoided when welding this type of steels.

  3. Incorporating a Time Horizon in Rate-of-Return Estimations: Discounted Cash Flow Model in Electric Transmission Rate Cases

    SciTech Connect

    Chatterjee, Bishu; Sharp, Peter A.

    2006-07-15

    Electric transmission and other rate cases use a form of the discounted cash flow model with a single long-term growth rate to estimate rates of return on equity. It cannot incorporate information about the appropriate time horizon for which analysts' estimates of earnings growth have predictive powers. Only a non-constant growth model can explicitly recognize the importance of the time horizon in an ROE calculation. (author)

  4. Recent progress of abrasion-resistant materials: learning from nature.

    PubMed

    Meng, Jingxin; Zhang, Pengchao; Wang, Shutao

    2016-01-21

    Abrasion-resistant materials have attracted great attention for their broad applications in industry, biomedicine and military. However, the development of abrasion-resistant materials that have with unique features such as being lightweight and flexible remains a great challenge in order to satisfy unmet demands. The outstanding performance of natural abrasion-resistant materials motivates the development of new bio-inspired abrasion-resistant materials. This review summarizes the recent progress in the investigation of natural abrasion-resistant materials to explore their general design principles (i.e., the correlation between chemical components and structural features). Following natural design principles, several artificial abrasion-resistant materials have shown unique abrasion-resistant properties. The potential challenges in the future and possible solutions for designing bio-inspired abrasion-resistant materials are also briefly discussed. PMID:26335377

  5. A Model for Variable Levee Formation Rates in an Active Lava Flow

    NASA Technical Reports Server (NTRS)

    Glaze, L. S.; Baloga, S. M.; Mouginis-Mark, P.; Crisp, J.

    2004-01-01

    Channelized lava flows on Mars and the Earth often feature levees and collateral margins that change in volume along the path of the flow. Consistent with field observations of terrestrial flows, this suggests that the rate of levee formation varies with distance and other factors. Previous models have assumed a constant rate of levee growth, specified by a single parameter, lambda. The rate of levee formation for lava flows is a good indicator of the mass eruption rate and rheology of the flow. Insight into levee formation will help us better understand whether or not the effusion rate was constant during an eruption, and once local topography is considered, allows us to look at cooling and/or rheology changes downslope. Here we present a more realistic extension of the levee formation model that treats the rate of levee growth as a function of distance along the flow path. We show how this model can be used with a terrestrial flow and a long lava flow on Mars. The key statement of the new formulation is the rate of transfer from the active component to the levees (or other passive components) through an element dx along the path of the flow. This volumetric transfer equation is presented.

  6. Gas, liquids flow rates hefty at Galveston Bay discovery

    SciTech Connect

    Petzet, G.A.

    1998-01-19

    Extended flow tests indicate a large Vicksburg (Oligocene) gas, condensate, and oil field is about to be developed in western Galveston Bay. Internal estimates indicates that ultimate recovery from the fault block in which the discovery well was drilled could exceed 1 tcf of gas equivalent of proved, possible, and probable reserves. The paper discusses the test program for this field and other prospects in the Galveston Bay area.

  7. The rock abrasion record at Gale Crater: Mars Science Laboratory results from Bradbury Landing to Rocknest

    NASA Astrophysics Data System (ADS)

    Bridges, N. T.; Calef, F. J.; Hallet, B.; Herkenhoff, K. E.; Lanza, N. L.; Le Mouélic, S.; Newman, C. E.; Blaney, D. L.; Pablo, M. A.; Kocurek, G. A.; Langevin, Y.; Lewis, K. W.; Mangold, N.; Maurice, S.; Meslin, P.-Y.; Pinet, P.; Renno, N. O.; Rice, M. S.; Richardson, M. E.; Sautter, V.; Sletten, R. S.; Wiens, R. C.; Yingst, R. A.

    2014-06-01

    Ventifacts, rocks abraded by wind-borne particles, are found in Gale Crater, Mars. In the eastward drive from "Bradbury Landing" to "Rocknest," they account for about half of the float and outcrop seen by Curiosity's cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from submillimeter lineations to centimeter-scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high-speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today.

  8. The rock abrasion record at Gale Crater: Mars Science Laboratory results from Bradbury Landing to Rocknest

    USGS Publications Warehouse

    Bridges, N.T.; Calef, F.J., III; Hallett, B.W.; Herkenhoff, Kenneth E.; Lanza, N.L.; Le Mouélic, S.; Newman, C.E.; Blaney, D.L.; de Pablo, M.A.; Kocurek, G.A.; Langevin, Y.; Lewis, K.W.; Mangold, N.; Maurice, S.; Meslin, P.-Y.; Pinet, P.; Renno, N.O.; Rice, CM.S.; Richardson, M.E.; Sautter, V.; Sletten, R.S.; Wiens, R.C.; Yingst, R.A.

    2014-01-01

    Ventifacts, rocks abraded by wind-borne particles, are found in Gale Crater, Mars. In the eastward drive from “Bradbury Landing” to “Rocknest,” they account for about half of the float and outcrop seen by Curiosity's cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from submillimeter lineations to centimeter-scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high-speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today.

  9. 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.

  10. A Novel Microfluidic Flow Rate Detection Method Based on Surface Plasmon Resonance Temperature Imaging

    PubMed Central

    Deng, Shijie; Wang, Peng; Liu, Shengnan; Zhao, Tianze; Xu, Shanzhi; Guo, Mingjiang; Yu, Xinglong

    2016-01-01

    A novel microfluidic flow rate detection method based on surface plasmon resonance (SPR) temperature imaging is proposed. The measurement is performed by space-resolved SPR imaging of the flow induced temperature variations. Theoretical simulations and analysis were performed to demonstrate a proof of concept using this approach. Experiments were implemented and results showed that water flow rates within a wide range of tens to hundreds of μL/min could be detected. The flow rate sensor is resistant to disturbances and can be easily integrated into microfluidic lab-on-chip systems. PMID:27347960

  11. A Novel Microfluidic Flow Rate Detection Method Based on Surface Plasmon Resonance Temperature Imaging.

    PubMed

    Deng, Shijie; Wang, Peng; Liu, Shengnan; Zhao, Tianze; Xu, Shanzhi; Guo, Mingjiang; Yu, Xinglong

    2016-01-01

    A novel microfluidic flow rate detection method based on surface plasmon resonance (SPR) temperature imaging is proposed. The measurement is performed by space-resolved SPR imaging of the flow induced temperature variations. Theoretical simulations and analysis were performed to demonstrate a proof of concept using this approach. Experiments were implemented and results showed that water flow rates within a wide range of tens to hundreds of μL/min could be detected. The flow rate sensor is resistant to disturbances and can be easily integrated into microfluidic lab-on-chip systems. PMID:27347960

  12. Investigation of the effect of wall friction on the flow rate in 2D and 3D Granular Flow

    NASA Astrophysics Data System (ADS)

    Carballo-Ramirez, Brenda; Pleau, Mollie; Easwar, Nalini; Birwa, Sumit; Shah, Neil; Tewari, Shubha

    We have measured the mass flow rate of spherical steel spheres under gravity in vertical, straight-walled 2 and 3-dimensional hoppers, where the flow velocity is controlled by the opening size. Our measurements focus on the role of friction and its placement along the walls of the hopper. In the 2D case, an increase in the coefficient of static friction from μ = 0.2 to 0.6 is seen to decrease the flow rate significantly. We have changed the placement of frictional boundaries/regions from the front and back walls of the 2D hopper to the side walls and floor to investigate the relative importance of the different regions in determining the flow rate. Fits to the Beverloo equation show significant departure from the expected exponent of 1.5 in the case of 2D flow. In contrast, 3D flow rates do not show much dependence on wall friction and its placement. We compare the experimental data to numerical simulations of gravity driven hopper granular flow with varying frictional walls constructed using LAMMPS*. *http://lammps.sandia.gov Supported by NSF MRSEC DMR 0820506.

  13. Distributed measurement of flow rate in conduits using heated fiber optic distributed temperature sensing

    NASA Astrophysics Data System (ADS)

    Sánchez, Raúl; Zubelzu, Sergio; Rodríguez-Sinobas, Leonor; Juana, Luis

    2016-04-01

    In some cases flow varies along conduits, such as in irrigated land drainage pipes and channels, irrigation laterals and others. Detailed knowledge of flow rate along the conduit makes possible analytical evaluation of water distribution and collection systems performance. Flow rate can change continuously in some systems, like in drainage pipes and channels, or abruptly, like in conduits bifurcations or emitter insertions. A heat pulse along the conduit makes possible to get flow rate from continuity and heat balance equations. Due to the great value of specific heat of water, temperature changes along conduit are smaller than the noise that involves the measurement process. This work presents a methodology that, dealing with the noise of distributed temperature measurements, leads to flow rate determination along pressurized pipes or open channel flows.

  14. 30 CFR 75.1101-19 - Nozzles; flow rate and direction.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Nozzles; flow rate and direction. 75.1101-19...; flow rate and direction. The nozzles of each dry powder chemical system shall be capable of discharging... minimize the effect of ventilation upon fire control....

  15. 30 CFR 75.1101-19 - Nozzles; flow rate and direction.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Nozzles; flow rate and direction. 75.1101-19...; flow rate and direction. The nozzles of each dry powder chemical system shall be capable of discharging... minimize the effect of ventilation upon fire control....

  16. Determining seed cotton mass flow rate by pressure drop across a blowbox

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A seed cotton mass flow rate sensor would offer useful feedback for gin managers and provide a critical input for advanced process control systems. Several designs of seed cotton mass flow rate sensors have been evaluated in the laboratory, but none have found acceptance in commercial gins. The obje...

  17. Determining Seed Cotton Mass Flow Rate by Pressure Drop Across a Blowbox: Gin Testing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate measurement of the mass flow rate of seed cotton is needed for control and monitoring purposes in gins. A system was developed that accurately predicted mass flow rate based on the static pressure drop measured across the blowbox and the air velocity and temperature entering the blowbox. Ho...

  18. Determining seed cotton mass flow rate by pressure drop across a blowbox

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A seed cotton mass flow rate sensor would offer useful feedback for gin managers and provide a critical input for advanced process control systems. Several designs of seed cotton mass flow rate sensors have been evaluated in the laboratory, but none have found acceptance in commercial gins. The ob...

  19. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... exceeded. (j) All employees using abrasive wheels shall be protected by eye protection equipment in accordance with the requirements of subpart I of this part except when adequate eye protection is afforded by eye shields which are permanently attached to the bench or floor stand....

  20. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  1. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  2. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  3. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  4. Evaluation and Treatment of Perioperative Corneal Abrasions

    PubMed Central

    Segal, Kira L.; Fleischut, Peter M.; Kim, Charles; Levine, Ben; Faggiani, Susan L.; Banerjee, Samprit; Gadalla, Farida; Lelli, Gary J.

    2014-01-01

    Purpose. To evaluate perioperative risk factors for corneal abrasion (CA) and to determine current care for perioperative CA in a tertiary care setting. Methods. Hospital-based, cross-sectional study. In Operating Room and Post-Anesthesia Care Units patients, a comparison of cases and controls was evaluated to elucidate risk factors, time to treatment, and most common treatments prescribed for corneal abrasions. Results. 86 cases of corneal abrasion and 89 controls were identified from the 78,542 surgical procedures performed over 2 years. Statistically significant risk factors were age (P = 0.0037), general anesthesia (P < 0.001), greater average estimated blood loss (P < 0.001), eyes taped during surgery (P < 0.001), prone position (P < 0.001), trendelenburg position (P < 0.001), and supplemental oxygen en route to and in the Post-Anesthesia Care Units (P < 0.001). Average time to complaint was 129 minutes. 94% of cases had an inpatient ophthalmology consult, with an average time to consult of 164 minutes. The most common treatment was artificial tears alone (40%), followed by combination treatment of antibiotic ointment and artificial tears (35.3%). Conclusions. Trendelenburg positioning is a novel risk factor for CA. Diagnosis and treatment of perioperative corneal abrasions by an ophthalmologist typically require three hours in the tertiary care setting. PMID:24672709

  5. 30 CFR 58.610 - Abrasive blasting.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... miners shall use in accordance with 30 CFR 56.5005 or 57.5005 respirators approved for abrasive blasting by NIOSH under 42 CFR part 84, or the operation shall be performed in a totally enclosed device with the miner outside the device. (b) Underground areas of underground mines. Silica sand or...

  6. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Abrasive wheels. 1915.134 Section 1915.134 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Tools and Related...

  7. 29 CFR 1915.134 - Abrasive wheels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Abrasive wheels. 1915.134 Section 1915.134 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Tools and Related...

  8. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  9. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  10. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  11. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  12. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  13. Numerical Simulation Study of Influence of Nozzle Entrance Diameter on Jet Performance of Pre-mixed Abrasive Water Jet

    NASA Astrophysics Data System (ADS)

    Guan, Jinfa; Deng, Songsheng; Jiao, Guangwei; Chen, Ming; Hua, Weixing

    Physical model of cone-cylinder nozzle was established. Based on the CFD software of FLUENT, the flow field about abrasive water jet in cone-cylinder nozzle was simulated by use of standard k-ɛ turbulent model, Lagrange Discrete Phase Model and SIMPLE algorithm. The simulation results show that axial velocity of abrasive particle is always smaller than axial velocity of abrasive particle and increases gradually with the increase of axial distance. Axial static pressure of water decreases gradually with the increase of axial distance. Axial velocity of abrasive particle at the exit of cone-cylinder nozzle decreases with the increase of nozzle entrance diameter. And axial static pressure of water at the entrance of cone-cylinder nozzle decreases with the increase of nozzle entrance diameter. 8mm is selected as an optimal nozzle entrance diameter.

  14. Measuring the rate of local evaporation from the liquid surface under the action of gas flow

    NASA Astrophysics Data System (ADS)

    Lyulin, Yu. V.; Feoktistov, D. V.; Afanas'ev, I. A.; Chachilo, E. S.; Kabov, O. A.; Kuznetsov, G. V.

    2015-07-01

    The dynamics of evaporation from the surface of a liquid layer under the action of a gas flow has been studied. Correlation dependences of the rate of liquid evaporation on the gas flow rate and temperature for the ethanol-air system have been obtained and compared to other published experimental data. It is established that, for the two-phase systems studied, the evaporation rate growth with increasing temperature exhibits an almost identical character independently of the thermal properties of particular liquids and gases. In contrast, the character of the evaporation rate growth with increasing gas flow velocity significantly depends on these properties.

  15. Application of Lorentz force techniques for flow rate measurement

    NASA Astrophysics Data System (ADS)

    Ebert, Reschad Johann; Resagk, Christian

    2014-11-01

    We report on the progress of the Lorentz force velocimetry (LFV): a contactless non-invasive flow velocity measurement technique. This method has been developed and demonstrated for various applications in our institute and in industry. At applications for weakly conducting fluids such as electrolytes with conductivities in the range of 1 - 10 S/m the challenging bottleneck is the detection of the tiny Lorentz forces in the noisy environment of the test channel. For the force measurement a state-of-the-art electromagnetic force compensation balance is used. Due to this device the mass of the Lorentz force generating magnets is limited. For enabling larger magnet systems and for higher force signals we have developed and tested a buoyancy based weight force compensation method which will be presented here. Additionally, results of LFV measurements at non-symmetric fluid profiles will be shown. By that an evaluation of the feasibility of this measurement principle for disturbed fluid profiles that are relevant for developing the LFV for weakly conducting fluids towards industrial applications can be made. Additionally a prospective setup for using the LFV for molten salt flows will be explained.

  16. Lab-scale ash production by abrasion and collision experiments of porous volcanic samples

    NASA Astrophysics Data System (ADS)

    Mueller, S. B.; Lane, S. J.; Kueppers, U.

    2015-09-01

    In the course of explosive eruptions, magma is fragmented into smaller pieces by a plethora of processes before and during deposition. Volcanic ash, fragments smaller than 2 mm, has near-volcano effects (e.g. increasing mobility of PDCs, threat to human infrastructure) but may also cause various problems over long duration and/or far away from the source (human health and aviation matters). We quantify the efficiency of ash generation during experimental fracturing of pumiceous and scoriaceous samples subjected to shear and normal stress fields. Experiments were designed to produce ash by overcoming the yield strength of samples from Tenerife (Canary Islands, Spain), Sicily and Lipari Islands (Italy), with this study having particular interest in the < 355 μm fraction. Fracturing within volcanic conduits, plumes and pyroclastic density currents (PDCs) was simulated through a series of abrasion (shear) and collision (normal) experiments. An understanding of these processes is crucial as they are capable of producing very fine ash (< 10 μm). These particles can remain in the atmosphere for several days and may travel large distances (~ 1000s of km). This poses a threat to the aviation industry and human health. From the experiments we establish that abrasion produced the finest-grained material and up to 50% of the generated ash was smaller than 10 μm. In comparison, the collision experiments that applied mainly normal stress fields produced coarser grain sizes. Results were compared to established grain size distributions for natural fall and PDC deposits and good correlation was found. Energies involved in collision and abrasion experiments were calculated and showed an exponential correlation with ash production rate. Projecting these experimental results into the volcanic environment, the greatest amounts of ash are produced in the most energetic and turbulent regions of volcanic flows, which are proximal to the vent. Finest grain sizes are produced in PDCs

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  18. Measurement of Retinal Blood Flow Rate in Diabetic Rats: Disparity Between Techniques Due to Redistribution of Flow

    PubMed Central

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

    2013-01-01

    Purpose. Reports of altered retinal blood flow in experimental models of type I diabetes have provided contrasting results, which leads to some confusion as to whether flow is increased or decreased. The purpose of our study was to evaluate early diabetes-induced changes in retinal blood flow in diabetic rats, using two distinctly different methods. Methods. Diabetes was induced by injection of streptozotocin (STZ), and retinal blood flow rate was measured under anesthesia by a microsphere infusion technique, or by an index of flow based on the mean circulation time between arterioles and venules. Measurements in STZ rats were compared to age-matched nondiabetic controls. In addition, the retinal distribution of fluorescently-labeled red blood cells (RBCs) was viewed by confocal microscopy in excised flat mounts. Results. Retinal blood flow rate was found to decrease by approximately 33% in the STZ rats compared to controls (P < 0.001) as assessed by the microsphere technique. However, in striking contrast, the mean circulation time through the retina was found to be almost 3× faster in the STZ rats (P < 0.01). This contradiction could be explained by flow redistribution through the superficial vessels of the diabetic retina, with this possibility supported by our observation of significantly fewer RBCs flowing through the deeper capillaries. Conclusions. We conclude that retinal blood flow rate is reduced significantly in the diabetic rat, with a substantial decrease of flow through the capillaries due to shunting of blood through the superficial layer, allowing rapid transit from arterioles to venules. PMID:23572104

  19. High flow rate nozzle system with production of uniform size droplets

    DOEpatents

    Stockel, I.H.

    1990-10-16

    Method steps for production of substantially uniform size droplets from a flow of liquid include forming the flow of liquid, periodically modulating the momentum of the flow of liquid in the flow direction at controlled frequency, generating a cross flow direction component of momentum and modulation of the cross flow momentum of liquid at substantially the same frequency and phase as the modulation of flow direction momentum, and spraying the so formed modulated flow through a first nozzle outlet to form a desired spray configuration. A second modulated flow through a second nozzle outlet is formed according to the same steps, and the first and second modulated flows impinge upon each other generating a liquid sheet. Nozzle apparatus for modulating each flow includes rotating valving plates interposed in the annular flow of liquid. The plates are formed with radial slots. Rotation of the rotating plates is separably controlled at differential angular velocities for a selected modulating frequency to achieve the target droplet size and production rate for a given flow. The counter rotating plates are spaced to achieve a desired amplitude of modulation in the flow direction, and the angular velocity of the downstream rotating plate is controlled to achieve the desired amplitude of modulation of momentum in the cross flow direction. Amplitude of modulation is set according to liquid viscosity. 5 figs.

  20. High flow rate nozzle system with production of uniform size droplets

    DOEpatents

    Stockel, Ivar H.

    1990-01-01

    Method steps for production of substantially uniform size droplets from a flow of liquid include forming the flow of liquid, periodically modulating the momentum of the flow of liquid in the flow direction at controlled frequency, generating a cross flow direction component of momentum and modulation of the cross flow momentum of liquid at substantially the same frequency and phase as the modulation of flow direction momentum, and spraying the so formed modulated flow through a first nozzle outlet to form a desired spray configuration. A second modulated flow through a second nozzle outlet is formed according to the same steps, and the first and second modulated flows impinge upon each other generating a liquid sheet. Nozzle apparatus for modulating each flow includes rotating valving plates interposed in the annular flow of liquid. The plates are formed with radial slots. Rotation of the rotating plates is separably controlled at differential angular velocities for a selected modulating frequency to achieve the target droplet size and production rate for a given flow. The counter rotating plates are spaced to achieve a desired amplitude of modulation in the flow direction, and the angular velocity of the downstream rotating plate is controlled to achieve the desired amplitude of modulation of momentum in the cross flow direction. Amplitude of modulation is set according to liquid viscosity.

  1. Abrasion in pyroclastic density currents: Insights from tumbling experiments

    NASA Astrophysics Data System (ADS)

    Kueppers, Ulrich; Putz, Constanze; Spieler, Oliver; Dingwell, Donald B.

    2012-01-01

    During granular mass movements of any kind, particles may interact with one another. The degree of interaction is a function of several variables including; grain-size distribution, particle concentration, density stratification and degree of fluidisation. The impact of particle interaction is additionally influenced by the relative speed, impact angle and clast temperature. Thus, both source conditions and transport-related processes are expected to influence the flow dynamics of pyroclastic density currents and their subsequent deposition. Here, we use tumbling experiments to shed light on the susceptibility of porous clasts to abrasion. We investigated the abrasion of unaltered volcanic rocks (5.7-80 vol.% porosity) from Unzen (Japan), Bezymianny (Russia) and Santorini (Greece) volcanoes as well as one synthetic analogue material, an insulating material with the trade name Foamglas® (95 vol.% porosity). Each experiment started with angular fragments generated in a jaw crusher from larger clasts. Two experimental series were performed; on samples with narrow and broader grain-size distributions, respectively. The dry samples were subject to rotational movement at constant speed and ambient temperature in a gum rotational tumbler for durations of 15, 30, 45, 60 and 120 min. The amount of volcanic ash (particles <2 mm) generated was evaluated as a function of experimental duration and sample porosity. We term “abrasion” as the ash fraction generated during the experiments. The observed increase of “abrasion” with increasing sample porosity and experimental duration is initially non-linear but becomes linear for experiments of 30 min duration or longer. For any given sample, abrasion appears to be more effective for coarser samples and larger initial mass. The observed range of ash generated in our experiments is between 1 and 35 wt.%. We find that this amount generally increases with increasing initial clast size or increasing breadth of the initial grain

  2. Sensitivity to edge and flow rate in the control of speed and altitude

    NASA Technical Reports Server (NTRS)

    Wolpert, Lawrence

    1991-01-01

    A number of studies have examined the potential efficacy of global flow rate and edge rate for specifying changes in self-motion. These have ranged from passive judgements of simulated accelerating self-motion to the active control of altitude in the presence of changes in flow and edge rates. A number of these studies are summarized and an attempt is made to reconcile their respective findings.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. Effects of Upstream Turbulence on Measurement Uncertainty of Flow Rate by Venturi

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

    Venturi has been widely used for measuring flow rate in a variety of engineering applications since pressure loss is relatively small compared with other measuring method. The current study focuses on making detailed estimation of measured uncertainties as the upstream turbulence affects uncertainty levels of the water flows in the closed-loop testing. Upstream turbulences can be controlled by selecting 9 different swirl generators. Measurement uncertainty of flow rate has been estimated by a quantitative uncertainty analysis which is based on the ANSI/ASME PTC 19.1-2005 standard. The best way to reduce error in measuring flow rate was investigated for evaluating its measurement uncertainty. The results of flow rate uncertainty analysis show that the case with systematic error has higher than that without systematic error. Especially the result with systematic error exhibits that the uncertainty of flow rate was gradually increased by upstream turbulence. Uncertainty of flow rate measurement can be mainly affected by differential pressure and discharge coefficient. Flow disturbance can be also reduced by increasing of the upstream straight length of Venturi.

  5. Comparative Evaluation of Gingival Depigmentation using Tetrafluoroethane Cryosurgery and Gingival Abrasion Technique: Two Years Follow Up

    PubMed Central

    Kumar, Santhosh; Bhat, G. Subraya; Bhat, K. Mahalinga

    2013-01-01

    Objective: A comparative evaluation of the gingival depigmentation by using Tetrafluoroethane cryosurgery and the gingival abrasion technique – 2 years of follow up. Material and Methods: Ten systemically healthy patients who were aged 18 to 36 years were selected for the study. Tetrafluoroethane was used for the cryosurgical depigmentation and the gingival abrasion technique used a coarse flame shaped bur. The presence or absence of pigmentation was tabulated, based on the GPI (Gingival Pigmentation Index). For the statistical analysis, Freidman’s test was used. Results: The keratinization was completed within a week after the application of the cryogen and about 10 days after the gingival abrasion technique was done. The statistical analysis which was done after 90th, 180th days and 2 years. The p-value which was obtained (p<.001) showed the superiority of cryosurgery over the gingival abrasion. During the follow up period, no side effects were seen for both the techniques and the improved aesthetics was maintained upto 2 years. Conclusion: The use of cryogen Tetrafluoroethane is easy, practical and inexpensive as compared to gingival abrasion, due to its high rate of recurrence. Hence, it is more acceptable to the patients and the operator. Further studies are needed to assess the long term effectiveness of the cryosurgical method of depigmentation. PMID:23543863

  6. [Grinding of titanium. 1. Commercial and experimental wheels made of silicon carbide abrasives].

    PubMed

    Miyakawa, O; Watanabe, K; Okawa, S; Nakano, S; Shiokawa, N; Kobayashi, M; Tamura, H

    1990-01-01

    Cast titanium was ground with commercial and experimental wheels made of silicon carbide abrasives, and their grinding performance was investigated. With the vitrified wheels made of the GC abrasive, at a higher the wheel circumferential speed and heavier the grinding pressure, the cutting rate was greater, accompanied by violent wear of the wheel. Being independent of the wheel speed, the grinding ratio reached about 1 under pressure heavier than 100 gf. The MgO-MgCl2-bonded wheels of the C abrasive exhibited a similar tendency. The manner in which the wheel was moved over the work during grinding proved to be very important, compared with the Ni-Cr alloy as reported previously. Only depression of the wheel against the work resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn, due to oxidation of titanium. Even when the wheel was moved over the work, chip-formation process of the cutting edge was far from ideal, and the work surface was contaminated due to reaction of titanium with the abrasive. At a higher wheel circumferential speed, more chips were loaded or built-up in the wheel and strongly rubbed the work surface, resulting in violent wear of the wheel; loading and dislodging of such chips were repeated. PMID:2134811

  7. Comparison between PEEK and Ti6Al4V concerning micro-scale abrasion wear on dental applications.

    PubMed

    Sampaio, M; Buciumeanu, M; Henriques, B; Silva, F S; Souza, J C M; Gomes, J R

    2016-07-01

    In the oral cavity, abrasive wear is predictable at exposed tooth or restorative surfaces, during mastication and tooth brushing. Also, wear can occur at contacting surfaces between the Ti-based prosthetic structures and implants in presence of abrasive compounds from food or toothpaste. Thus, the aim of this work was to compare the abrasive wear resistance of PEEK and Ti6Al4V on three-body abrasion related to different hydrated silica content and loads. Surfaces of Ti6Al4V or PEEK cylinders (8mm diameter and 4mm height) were wet ground on SiC papers and then polished with 1µm diamond paste. After that, surfaces were ultrasonically cleaned in propyl alcohol for 15min and then in distilled water for 10min. Micro-scale abrasion tests were performed at 60rpm and on different normal loads (0.4, 0.8 or 1.2N) after 600 ball revolutions using suspensions with different weight contents of hydrated silica. After abrasive tests, wear scars on flat samples were measured to quantify the wear volume and characterized by scanning electron microscope (SEM) to identify the dominant wear mechanisms. Results showed a higher volume loss rate on PEEK than that recorded on Ti6Al4V,, when subjected to three-body abrasion tests involving hydrated silica suspensions. An increase in volume loss was noted on both tested materials when the abrasive content or load was increased. PEEK was characterized by less wear resistance than that on Ti6Al4V after micro-scale abrasion wear in contact with hydrated silica particles, as commonly found in toothpastes. PMID:26849309

  8. Prediction Of Abrasive And Diffusive Tool Wear Mechanisms In Machining

    NASA Astrophysics Data System (ADS)

    Rizzuti, S.; Umbrello, D.

    2011-01-01

    Tool wear prediction is regarded as very important task in order to maximize tool performance, minimize cutting costs and improve the quality of workpiece in cutting. In this research work, an experimental campaign was carried out at the varying of cutting conditions with the aim to measure both crater and flank tool wear, during machining of an AISI 1045 with an uncoated carbide tool P40. Parallel a FEM-based analysis was developed in order to study the tool wear mechanisms, taking also into account the influence of the cutting conditions and the temperature reached on the tool surfaces. The results show that, when the temperature of the tool rake surface is lower than the activation temperature of the diffusive phenomenon, the wear rate can be estimated applying an abrasive model. In contrast, in the tool area where the temperature is higher than the diffusive activation temperature, the wear rate can be evaluated applying a diffusive model. Finally, for a temperature ranges within the above cited values an adopted abrasive-diffusive wear model furnished the possibility to correctly evaluate the tool wear phenomena.

  9. Financial modeling in medicine: cash flow, basic metrics, the time value of money, discount rates, and internal rate of return.

    PubMed

    Lexa, Frank James; Berlin, Jonathan W

    2005-03-01

    In this article, the authors cover tools for financial modeling. Commonly used time lines and cash flow diagrams are discussed. Commonly used but limited terms such as payback and breakeven are introduced. The important topics of the time value of money and discount rates are introduced to lay the foundation for their use in modeling and in more advanced metrics such as the internal rate of return. Finally, the authors broach the more sophisticated topic of net present value. PMID:17411805

  10. Wheel Abrasion Experiment Conducted on Mars

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.

    1998-01-01

    Sojourner rover showing Lewis' wheel abrasion experiment. The Mars Pathfinder spacecraft soft-landed on Mars on July 4, 1997. Among the many experiments on its small Sojourner rover are three technology experiments from the NASA Lewis Research Center, including the Wheel Abrasion Experiment (WAE). The WAE was designed, built, delivered, and operated on Mars by a team of engineers and scientists from Lewis' Photovoltaics and Space Environments Branch. This experiment collected data to assess wheel surface wear on the Sojourner. It used a specially designed rover wheel, with thin films (200 to 1000 angstroms) of aluminum, nickel, and platinum deposited on black, anodized aluminum strips attached to the rover's right center wheel. As the wheel spun in the Martian soil, a photovoltaic sensor monitored changes in film reflectivity. These changes indicated abrasion of the metal films by Martian surface material. Rolling wear data were accumulated by the WAE. Also, at frequent intervals, all the rover wheels, except the WAE test wheel, were locked to hold the rover stationary while the test wheel alone was spun and dug into the Martian regolith. These tests created wear conditions more severe than simple rolling. The WAE will contribute substantially to our knowledge of Martian surface characteristics. Marked abrasion would indicate a surface composed of hard, possibly sharply edged grains, whereas lack of abrasion would suggest a somewhat softer surface. WAE results will be correlated with ground simulations to determine which terrestrial materials behave most like those on Mars. This knowledge will enable a deeper understanding of erosion processes on Mars and the role they play in Martian surface evolution. Preliminary results show that electrostatic charging of the rover wheels sometimes caused dust to accumulate on the WAE wheel, making interpretation of the reflectance data problematic. If electrostatic charging is the mechanism for dust attraction, this indicates

  11. Improvement in high stress abrasive wear property of steel by hardfacing

    SciTech Connect

    Kumar, S.; Mondal, D.P.; Khaira, H.K.; Jha, A.K.

    1999-12-01

    High stress abrasive wear behavior of mild steel, medium carbon steel, and hardfacing alloy has been studied to ascertain the extent of improvement in the wear properties after hardfacing of steel. High stress abrasive wear tests were carried out by sliding the specimen against the abrasive media consisting of silicon carbide particles, rigidly bonded on paper base and mounted on disk. Maximum wear was found in the case of mild steel followed by a medium carbon alloy steel and a hardfacing alloy. Different compositions of steels and constituent phases present led to different wear rates of the specimen. The extent of improvement in wear performance of steel due to hardfacing is quite appreciable (twice compared to mild steel). Microstructural examination of the wear surface has been carried out to understand the wear mechanism.

  12. Abrasive wear: The efects of fibres size on oil palm empty fruit bunch polyester composite

    NASA Astrophysics Data System (ADS)

    Kasolang, S.; Kalam, A.; Ahmad, M. A.; Rahman, N. A.; Suhadah, W. N.

    2012-06-01

    This paper presents an experimental investigation carried out to determine the effect of palm oil empty fruit bunch (OPEFB) fibre size in dry sliding testing of polyester composite. These composite samples were produced by mixing raw OPEFB fibre with resin. The samples were prepared at different sizes of fibre (100, 125, 180 and 250μm). Abrasion Resistance Tester (TR-600) was used to carried out abrasive wear tests in dry sliding conditions. These tests were performed at room temperature for two different loads (10 and 30N) and at a constant sliding velocity of 1.4m/s. The specific wear rates of OPEFB polyester composites were obtained. The morphology of composite surface before and after tests was also examined using 3D microscope imaging. Preliminary work on thermal distribution at the abrasive wheel point was also conducted for selected samples.

  13. Abrasion-Resistant Technology and its Prospect for CFB Boilers

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Li, Y. J.; Wang, L. J.; Liu, S. H.; Dou, Q. R.

    In recent years, CFB boilers (CFBB) have been widely used in the commercial power plants due to its environmental benefits, high combustion efficiency, wide coal flexibility, and some other advantages. At the same time, the abrasion problem, the greatest weakness of this kind of boiler, has been gradually exposed in its application process. The abrasion, particularly on key parts such as the heating surface of water-cooled wall, furnace corners, separator entrance, seriously restricts the long-period operation ability of the CFBB. This article discusses current development status for various abrasion resistant refractory materials used in a CFBB. Some comments are provided for developing new high-performance abrasion resistant refractory materials and rapid-repaired materials according to the abrasion principle and the abrasion on different parts, as well as the economical and environmental requirements for the material. The abrasion solution and operation period of CFBB can be better improved given realization.

  14. Quartz Measurement in Coal Dust with High-Flow Rate Samplers: Laboratory Study

    PubMed Central

    LEE, TAEKHEE; LEE, EUN GYUNG; KIM, SEUNG WON; CHISHOLM, WILLIAM P.; KASHON, MICHAEL; HARPER, MARTIN

    2015-01-01

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

  15. Investigation of flow rate in a quasi-2D hopper with two symmetric outlets

    NASA Astrophysics Data System (ADS)

    Zhang, Xuezhi; Zhang, Sheng; Yang, Guanghui; Lin, Ping; Tian, Yuan; Wan, Jiang-Feng; Yang, Lei

    2016-03-01

    In this study the flow rate in a quasi-2D hopper with two symmetric outlets was investigated numerically. When two outlets merge into one, the flow rate is obviously bigger than that with a large enough distance between them. To explain the influence of the interaction between these two outlets, it was found that the velocity field above one outlet will be affected by the neighboring outlet by reducing the stagnant zone. With increasing distance, this interaction becomes weaker. Finally the formula of flow rate considering various outlet sizes and distances is fitted to the simulation data.

  16. Onset Mechanism of Strain Rate Induced Flow Stress Up-turn

    SciTech Connect

    Fan, Yue; Osetskiy, Yury N; Yip, Sidney; Yildiz-Botterud, Bilge

    2012-01-01

    The strain-rate response of flow stress in a plastically deforming crystal is formulated through a stresssensitive dislocation mobility model that can be evaluated by atomistic simulation. For the flow stress of a model crystal of bcc Fe containing a 1/2 <111> screw dislocation, this approach describes naturally a non-Arrhenius upturn at high strain rate, an experimentally established transitional behavior for which the underlying mechanism has not been clarified. Implications of our findings regarding the previous explanations of strain-rate effects on flow stress are discussed.

  17. Flow variability of an aerial variable-rate nozzle at constant pressures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Variable-rate ground application systems have been in use for the past 15 years, but due to high application speeds, flow requirements, and aerodynamic considerations, variable-rate aerial nozzles have not been available until now. In 2006, Spray Target, Inc. released the VeriRate™ variable-rate aer...

  18. An efficient, explicit finite-rate algorithm to compute flows in chemical nonequilibrium

    NASA Technical Reports Server (NTRS)

    Palmer, Grant

    1989-01-01

    An explicit finite-rate code was developed to compute hypersonic viscous chemically reacting flows about three-dimensional bodies. Equations describing the finite-rate chemical reactions were fully coupled to the gas dynamic equations using a new coupling technique. The new technique maintains stability in the explicit finite-rate formulation while permitting relatively large global time steps.

  19. Does Water Content or Flow Rate Control Colloid Transport in Unsaturated Porous Media?

    SciTech Connect

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

    2014-03-01

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

  20. Natural-Scale Lava Flow Experiments on Video: Variations with Temperature, Slope, and Effusion Rate

    NASA Astrophysics Data System (ADS)

    Karson, J. A.; Wysocki, R.; Edwards, B. R.; Lev, E.

    2013-12-01

    Investigations of active basaltic lava flows and analog materials show that flow dynamics and final flow morphology are strongly determined by the rapidly evolving rheology of the lava crust which constrains the downslope advance of the lava flow. The non-dimensional factor Ψ (ratio of the time scale of crust formation to advective heat loss) provides a useful means of comparing different flows. The key parameters that control Ψ include the melt viscosity, temperature, effusion rate, and slope. Experimental lava flows, up to several meters long created in the Syracuse University Lava Project permit these variables to be investigated independently and in combination in volume-limited flows (<450 kg, 0.5 m3). Video results show lava is very sensitive to relatively small variations in these variables under experimental conditions. For example, experiments 1.1 Ga Keewenan basalt from the Mid-Continent Rift and 200 Ma basalt from the Palisades Sill show very different flow rates and flow morphologies for meter-scale flows on dry sand slopes between 5° and 20°, with all other variables held constant. Similar differences result from varying the effusion rate (~10-4m3s-1) or temperature (1050°-1250°C) on a constant slope. In addition, videos document the development of a wide range of reproducible lava flow structures found in natural lava flows including folds, shear zones, lava tubes, inflated lobes, break-outs, and bubbles (limu o'Pele), that provide additional information on lava crust development. New, continuous flow (cooling-limited) experiments show downslope variations under constant flow conditions.

  1. Influence of impactor operating flow rate on particle size distribution of four jet nebulizers.

    PubMed

    Zhou, Yue; Brasel, Trevor L; Kracko, Dean; Cheng, Yung-Sung; Ahuja, Amitkumar; Norenberg, Jeffrey P; Kelly, H William

    2007-01-01

    When a nebulizer is evaluated by the Andersen Cascade Impactor (ACI), the flow rate is generally maintained at 28.3 L/min, as recommended by the manufacturer. However, the nebulizer flow rate that a patient inhales is only around 18 L/min. Because the drive flow of a nebulizer is approximately 6-8 L/min, the nebulized drug is mixed with outside air when delivered. Evaluating impactor performance at the 28.3 L/min flow rate is less than ideal because an additional 10 L/min of outside air is mixed with the drug, thereby affecting the drug size distribution and dose before inhalation and deposition in the human lung. In this study we operated the ACI at an 18.0 L/min flow rate to test whether the effect of the changing ambient humidity was being exaggerated by the 28.3 L/min flow rate. The study was carried out at three different relative humidity levels and two different impactor flow rates with four commercially available nebulizers. The mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD) of the droplets were found to increase when the impactor was operated at a flow rate of 18 L/min compared to that of 28.3 L/min. The higher MMAD and GSD could cause the patient to inhale less of the drug than expected if the nebulizer was evaluated by the ACI at the operating flow rate of 28.3 L/min. PMID:17763140

  2. Effects of flow rate and temperature on cyclic gas exchange in tsetse flies (Diptera, Glossinidae).

    PubMed

    Terblanche, John S; Chown, Steven L

    2010-05-01

    Air flow rates may confound the investigation and classification of insect gas exchange patterns. Here we report the effects of flow rates (50, 100, 200, 400 ml min(-1)) on gas exchange patterns in wild-caught Glossina morsitans morsitans from Zambia. At rest, G. m. morsitans generally showed continuous or cyclic gas exchange (CGE) but no evidence of discontinuous gas exchange (DGE). Flow rates had little influence on the ability to detect CGE in tsetse, at least in the present experimental setup and under these laboratory conditions. Importantly, faster flow rates resulted in similar gas exchange patterns to those identified at lower flower rates suggesting that G. m. morsitans did not show DGE which had been incorrectly identified as CGE at lower flow rates. While CGE cycle frequency was significantly different among the four flow rates (p<0.05), the direction of effects was inconsistent. Indeed, inter-individual variation in CGE cycle frequency exceeded flow rate treatment variation. Using a laboratory colony of closely related, similar-sized G. morsitans centralis we subsequently investigated the effects of temperature, gender and feeding status on CGE pattern variation since these factors can influence insect metabolic rates. At 100 ml min(-1) CGE was typical of G. m. centralis at rest, although it was significantly more common in females than in males (57% vs. 43% of 14 individuals tested per gender). In either sex, temperature (20, 24, 28 and 32 degrees C) had little influence on the number of individuals showing CGE. However, increases in metabolic rate with temperature were modulated largely by increases in burst volume and cycle frequency. This is unusual among insects showing CGE or DGE patterns because increases in metabolic rate are usually modulated by increases in frequency, but either no change or a decline in burst volume. PMID:20399350

  3. Method and apparatus for measuring the mass flow rate of a fluid

    DOEpatents

    Evans, Robert P.; Wilkins, S. Curtis; Goodrich, Lorenzo D.; Blotter, Jonathan D.

    2002-01-01

    A non invasive method and apparatus is provided to measure the mass flow rate of a multi-phase fluid. An accelerometer is attached to a pipe carrying a multi-phase fluid. Flow related measurements in pipes are sensitive to random velocity fluctuations whose magnitude is proportional to the mean mass flow rate. An analysis of the signal produced by the accelerometer shows a relationship between the mass flow of a fluid and the noise component of the signal of an accelerometer. The noise signal, as defined by the standard deviation of the accelerometer signal allows the method and apparatus of the present invention to non-intrusively measure the mass flow rate of a multi-phase fluid.

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

    DOEpatents

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

    2016-03-08

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

  5. Liquid abrasive pressure pot scoping tests report

    SciTech Connect

    Archibald, K.E.

    1996-01-01

    The primary initiatives of the LITCO Decontamination Development group at the Idaho Chemical Process Plant (ICPP) are the development of methods to eliminate the use of sodium bearing decontamination chemicals and minimization of the amount of secondary waste generated during decontamination activities. In July of 1994, a Commerce Business Daily (CBD) announcement was issued by the INEL to determine commercial interest in the development of an in-situ liquid abrasive grit blasting system. As a result of the CBD announcement, Klieber & Schulz issued an Expression of Interest letter which stated they would be interested in testing a prototype Liquid Abrasive Pressure Pot (LAPP). LITCO`s Decontamination group and Kleiber & Schulz entered into a Cooperative Research and Development Agreement (CRADA) in which the Decontamination Development group tested the prototype LAPP in a non-radioactive hot cell mockup. Test results are provided.

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

    NASA Astrophysics Data System (ADS)

    Zhao, Kunmin; Fan, Rong; Wang, Limin

    2016-03-01

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

  7. Effects of gas flow rate on deposition rate and number of Si clusters incorporated into a-Si:H films

    NASA Astrophysics Data System (ADS)

    Toko, Susumu; Torigoe, Yoshihiro; Keya, Kimitaka; Seo, Hyunwoong; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2016-01-01

    The suppression of cluster incorporation into a-Si:H films is the key to better film stability, because incorporated clusters contribute to the formation of SiH2 bonds and hence lead to light-induced degradation of the films. To deposit stable a-Si:H solar cells at a high deposition rate (DR), we studied the effects of the gas flow rate on DR and the number of Si clusters incorporated into a-Si:H films with discharge power as a parameter, using a multihollow discharge-plasma chemical vapor deposition method. We succeeded in depositing high-quality a-Si:H films with the incorporation of few clusters at DR of 0.1 nm/s. We also found that, under a low gas flow rate and a high discharge power, high-density clusters exist in plasma and hence DR is reduced as a result of radical loss to the clusters.

  8. Abrasive slurry composition for machining boron carbide

    DOEpatents

    Duran, Edward L.

    1985-01-01

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  9. Abrasive slurry composition for machining boron carbide

    DOEpatents

    Duran, E.L.

    1984-11-29

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  10. Mechanisms of microhole formation on glasses by an abrasive slurry jet

    SciTech Connect

    Wang, J.; Nguyen, T.; Pang, K. L.

    2009-02-15

    Abrasive jet micromachining is considered as a promising precision processing technology for brittle materials such as silicon substrates and glasses that are increasingly used in various applications. In this paper, the mechanisms of microhole formation on brittle glasses by an abrasive slurry jet are studied based on the viscous flow and erosion theories. It is shown that the hole cross section is characterized by a ''W'' shape and can be classified into three zones caused, respectively, by jet direct impact, viscous flow, and turbulent flow induced erosion. An analysis of the surface morphology shows that ductile-mode erosion is dominant. The effect of process parameters on material removal is studied which shows that increasing the pressure and erosion time increases the hole depth, but has little effect on the hole diameter.

  11. Effects of nitrogen flow rate on the properties of indium oxide thin films.

    PubMed

    Cho, Shinho; Kim, Moonhwan

    2013-11-01

    Indium oxide thin films are deposited on glass substrates at nitrogen flow rates of 0-50% by rf reactive magnetron sputtering and are characterized for their structural, morphological, electrical, and optical properties. The experimental results showed that the control of nitrogen flow rate has a significant effect on the properties of the In2O3 thin films. The change in the preferred growth orientation from (222) to (400) planes is observed above a nitrogen flow rate of 10%. The average optical transmittance in the wavelength range of 400-1100 nm is increased from 85.4% at 0% to 86.7% at 50%, where the smallest value of the optical band gap energy is obtained. In addition to the improvement in crystallinity of the films, the nitrogen flow rate plays a crucial role in the fabrication of high-quality indium oxide films and devices. PMID:24245335

  12. Coal flow aids reduce coke plant operating costs and improve production rates

    SciTech Connect

    Bedard, R.A.; Bradacs, D.J.; Kluck, R.W.; Roe, D.C.; Ventresca, B.P.

    2005-06-01

    Chemical coal flow aids can provide many benefits to coke plants, including improved production rates, reduced maintenance and lower cleaning costs. This article discusses the mechanisms by which coal flow aids function and analyzes several successful case histories. 2 refs., 10 figs., 1 tab.

  13. Direct Measurement of Planar Flow Rate in Excised Canine Larynx Model

    PubMed Central

    Oren, Liran; Khosla, Sid; Dembinski, Doug; Ying, Jun; Gutmark, Ephraim

    2014-01-01

    Objective During phonation, skewing of the glottal flow waveform (Q) during phonation refers to a phenomenon that occurs when the flow decelerates more rapidly than it accelerates. This skewing is clinically important because it increases the glottal efficiency, which is defined by the acoustic intensity (units are sound pressure level or SPL) divided by the subglottal pressure. Current theoretical models predict that the only mechanism to cause skewing of Q involves changes in the vocal tract inertance. The purpose of the current work is to show that other factors at the vocal fold level can also cause skewing of Q and to determine if the acoustic intensity is correlated with MFDR. Study design Basic Science Methods Intraglottal geometry and velocity measurements were taken in five canine larynges at the mid-membranous plane using two-dimensional particle imaging velocimetry (PIV). The flow rate at the glottal exit was computed from the PIV measurements for low, medium, and high subglottal pressures. Results Vortices form in the superior aspect of the divergent glottis during closing. These vortices produce negative pressure that increases both the maximum value of Q and the rapid deceleration of the flow. The skewing of the flow rate is increased as the intraglottal vortices are increased by increasing the subglottal pressure. The increase in the acoustic intensity is highly correlated with certain properties of the flow rate waveform, such as maximum flow rate. Conclusion Flow skewing and the acoustic intensity can be increased by increasing the intraglottal vortices. PMID:25093928

  14. Predicting abrasive wear with coupled Lagrangian methods

    NASA Astrophysics Data System (ADS)

    Beck, Florian; Eberhard, Peter

    2015-05-01

    In this paper, a mesh-less approach for the simulation of a fluid with particle loading and the prediction of abrasive wear is presented. We are using the smoothed particle hydrodynamics (SPH) method for modeling the fluid and the discrete element method (DEM) for the solid particles, which represent the loading of the fluid. These Lagrangian methods are used to describe heavily sloshing fluids with their free surfaces as well as the interface between the fluid and the solid particles accurately. A Reynolds-averaged Navier-Stokes equations model is applied for handling turbulences. We are predicting abrasive wear on the boundary geometry with two different wear models taking cutting and deformation mechanisms into account. The boundary geometry is discretized with special DEM particles. In doing so, it is possible to use the same particle type for both the calculation of the boundary conditions for the SPH method as well as the DEM and for predicting the abrasive wear. After a brief introduction to the SPH method and the DEM, the handling of the boundary and the coupling of the fluid and the solid particles are discussed. Then, the applied wear models are presented and the simulation scenarios are described. The first numerical experiment is the simulation of a fluid with loading which is sloshing inside a tank. The second numerical experiment is the simulation of the impact of a free jet with loading to a simplified pelton bucket. We are especially investigating the wear patterns inside the tank and the bucket.

  15. Circular Signs of the Rock Abrasion Tool

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image was taken by Mars Exploration Rover Opportunity's front hazard-avoidance camera, providing a circular sign of the success of the rover's first grinding of a rock. The round, shallow hole seen in this image is on a rock dubbed 'McKittrick,' located in the 'El Capitan' area of the larger outcrop near Opportunity's landing site.

    Opportunity used its rock abrasion tool to grind off a patch of rock 45.5 millimeters (1.8 inches) in diameter during the 30th martian day, or sol, of its mission (Feb. 23, 2004). The grinding exposed fresh rock for close inspection by the rover's microscopic imager and two spectrometers located on its robotic arm. The Honeybee Robotics team, which designed and operates the rock abrasion tool, determined the depth of the cut at 'McKittrick' to be 4.4 millimeters (0.17 inches) deep.

    On sol 34 (Feb. 27, 2004), the rover is scheduled to grind into its second target on the 'El Capitan' area, a rock dubbed 'Guadalupe' in the upper middle part of this image. The rock abrasion tools on both Mars Exploration Rovers were supplied by Honeybee Robotics, New York, N.Y.

  16. Measurement of cerebral blood flow rate and its relationship with brain function using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Liu, Jian; Wang, Yi; Zhao, Yuqian; Dou, Shidan; Ma, Yushu; Ma, Zhenhe

    2016-03-01

    Activity of brain neurons will lead to changes in local blood flow rate (BFR). Thus, it is important to measure the local BFR of cerebral cortex on research of neuron activity in vivo, such as rehabilitation evaluation after stroke, etc. Currently, laser Doppler flowmetry is commonly used for blood flow measurement, however, relatively low resolution limits its application. Optical coherence tomography (OCT) is a powerful noninvasive 3D imaging modality with high temporal and spatial resolutions. Furthermore, OCT can provide flow distribution image by calculating Doppler frequency shift which makes it possible for blood flow rate measurement. In this paper, we applied OCT to measure the blood flow rate of the primary motor cortex in rats. The animal was immobilized and anesthetized with isoflurane, an incision was made along the sagittal suture, and bone was exposed. A skull window was opened on the primary motor cortex. Then, blood flow rate changes in the primary motor cortex were monitored by our homemade spectral domain OCT with a stimulation of the passive movement of the front legs. Finally, we established the relationship between blood flow rate and the test design. The aim is to demonstrate the potential of OCT in the evaluation of cerebral cortex function.

  17. Are gingival and periodontal conditions related to salivary gland flow rates in healthy individuals?

    PubMed

    Crow, H C; Ship, J A

    1995-11-01

    Some have suggested that gingival and periodontal health is related to salivary gland function; however, there are few data to support this hypothesis. The purpose of this study was to determine if correlations existed between major salivary gland flow rates and gingival and periodontal conditions in people of different ages. The results suggest that there is no consistent relationship between major salivary gland flow rates and gingival and periodontal conditions in healthy people. PMID:7499648

  18. Cover and Erosion Asymmetry in Saltation-Abrasion

    NASA Astrophysics Data System (ADS)

    Stark, C. P.; Parker, G.

    2014-12-01

    Erosion in bedrock-floored rivers is both driven and limited by the amount of sediment transported along the bed. Some sediment boosts wear rates, whereas too much generates a protective cover. This phenomenon determines the shape of river channels in a variety of landscapes and limits how fast they evolve. Here we reevaluate data from a well-known bedrock wear experiment to throw new light on how the saltation-abrasion process. Instead of a symmetric form for erosion versus sediment flux relative to transport capacity, we find the erosion rate peak shifts towards lower sediment fluxes when blocking of oblique saltation trajectories is taken into account. The theoretical context for this reevaluation is a cover-saltation-abrasion model, based on queueing theory (QT), for bedload transport over a planar bedrock bed. The QT approach provides some clarity in the stochastic treatment of granular impacts and cover, and generates closed-form solutions for wear rate in terms of sediment flux and simplified saltation geometry. Applied to the Sklar & Dietrich (2001) experiments in a very small recirculating flume, the two-parameter QT model fits the observed relation between erosion rate and sediment load, infers sediment flux as a function of load, admits non-negligible wear rates for a mean sediment depth of one grain, i.e., for full cover on average, but also suggests that bedrock erosion is blocked at >=50% instantaneous cover. The QT model makes testable predictions for future laboratory experiments and highlights the need for specific improvements in more comprehensive treatments of bedrock erosion and cover.

  19. Performance of TSI 3760 condensation nuclei counter at reduced pressures and flow rates

    SciTech Connect

    Zhiqun Zhang; Liu, B.Y.H. )

    1991-01-01

    This article describes an experimental study of the performance of the TSI model 3760 clean room condensation nuclei counter (CNC) at various pressures and flow rates. Studies were made to determine the counting efficiency of the instrument in the pressure range of 0.1-1 atom and flow rate range of 0.15-1.4 L/min. The counting efficiency curves were found to be shifted to larger particle sizes as the pressure or flow rate was reduced. The low pressure and low flow rate limits of the instrument were also determined. The numerical model developed in a previous study was used to predict the performance of the CNC. The numerical results were compared with the experimental data and found to agree well in the pressure range of 0.2-1.0 atm and flow rate range of 0.3-1.4 L/min. Discrepancies were found to be more significant at the lower pressures and flow rates.

  20. Flow rate dictates permeability enhancement during fluid pressure oscillations in laboratory experiments

    NASA Astrophysics Data System (ADS)

    Candela, Thibault; Brodsky, Emily E.; Marone, Chris; Elsworth, Derek

    2015-04-01

    Seismic waves have been observed to increase the permeability in fractured aquifers. A detailed, predictive understanding of the process has been hampered by a lack of constraint on the primary physical controls. What aspect of the oscillatory forcing is most important in determining the magnitude of the permeability enhancement? Here we present laboratory results showing that flow rate is the primary control on permeability increases in the laboratory. We fractured Berea sandstone samples under triaxial stresses of tens of megapascals and applied dynamic fluid stresses via pore pressure oscillations. In each experiment, we varied either the amplitude or the frequency of the pressure changes. Amplitude and frequency each separately correlated with the resultant permeability increase. More importantly, the permeability changes correlate with the flow rate in each configuration, regardless of whether flow rate variations were driven by varying amplitude or frequency. We also track the permeability evolution during a single set of oscillations by measuring the phase lags (time delays) of successive oscillations. Interpreting the responses with a poroelastic model shows that 80% of the permeability enhancement is reached during the first oscillation and the final permeability enhancement scales exponentially with the imposed change in flow rate integrated over the rock volume. The establishment of flow rate as the primary control on permeability enhancement from seismic waves opens the door to quantitative studies of earthquake-hydrogeological coupling. The result also suggests that reservoir permeability could be engineered by imposing dynamic stresses and changes in flow rate.

  1. Flow rate dictates permeability enhancement during fluid pressure oscillations in laboratory experiments

    NASA Astrophysics Data System (ADS)

    Brodsky, E. E.; Candela, T.; Elsworth, D.; Marone, C.

    2014-12-01

    Seismic waves have been observed to increase the permeability in fractured aquifers. A detailed, predictive understanding of the process has been hampered by a lack of constraint on the primary physical controls. What aspect of the oscillatory forcing is most important in determining the magnitude of the permeability enhancement? Here we present laboratory results showing that flow rate is the primary control on permeability increases in the laboratory. We fractured Berea sandstone samples under triaxial stresses of tens of megapascals, and applied dynamic fluid-stresses via pore pressure oscillations. In each experiment, we varied either the amplitude or the frequency of the pressure changes. Amplitude and frequency each separately correlated with the resultant permeability increase. More importantly, the permeability changes correlate with the flow rate in each configuration, regardless of whether flow rate variations were driven by varying amplitude or frequency. We also track the permeability evolution during a single set of oscillations by measuring the phase lags (time delays) of successive oscillations. Interpreting the responses with a poroelastic model shows that 80% of the permeability enhancement is reached during the first oscillation and the final permeability enhancement scales exponentially with the imposed change in flow rate integrated over the rock volume. The establishment of flow rate as the primary control on permeability enhancement from seismic waves opens the door to quantitative studies of earthquake-hydrogeological coupling. The result also suggests that reservoir permeability could be engineered by imposing dynamic stresses and changes in flow rate.

  2. Pressure difference-flow rate variation in a femoral artery branch casting of man for steady flow

    NASA Technical Reports Server (NTRS)

    Cho, Y. I.; Back, L. H.; Crawford, D. W.

    1983-01-01

    In-vitro, steady flow in a casting of the profunda femoris branch of the femoral artery of man was studied by measuring pressure differences in the main lumen and also in the branch over a large Reynolds number range from 200 to 1600. Effects of viscous and inviscid flows in this femoral artery branch were demonstrated quantitatively. The critical ratio of the flow rate in the branch to the upstream main lumen in this casting was found to be 0.4, above which the inviscid flow analysis indicated a pressure rise and below which it yielded a pressure drop in the main lumen across the branch junction. Pressure rises were experimentally found to occur both in the main lumen and in the branch for certain ranges of the aforementioned ratio.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    PubMed

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

    2016-01-01

    Direct in vivo imaging of lymph flow is key to understanding lymphatic system function in normal and disease states. Optical microscopy techniques provide the resolution required for these measurements, but existing optical techniques for measuring lymph flow require complex protocols and provide limited temporal resolution. Here, we describe a Doppler optical coherence tomography platform that allows direct, label-free quantification of lymph velocity and volumetric flow rates. We overcome the challenge of very low scattering by employing a Doppler algorithm that operates on low signal-to-noise measurements. We show that this technique can measure lymph velocity at sufficiently high temporal resolution to resolve the dynamic pulsatile flow in collecting lymphatic vessels. PMID:27377852

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

    PubMed Central

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

    2016-01-01

    Direct in vivo imaging of lymph flow is key to understanding lymphatic system function in normal and disease states. Optical microscopy techniques provide the resolution required for these measurements, but existing optical techniques for measuring lymph flow require complex protocols and provide limited temporal resolution. Here, we describe a Doppler optical coherence tomography platform that allows direct, label-free quantification of lymph velocity and volumetric flow rates. We overcome the challenge of very low scattering by employing a Doppler algorithm that operates on low signal-to-noise measurements. We show that this technique can measure lymph velocity at sufficiently high temporal resolution to resolve the dynamic pulsatile flow in collecting lymphatic vessels. PMID:27377852

  6. Martian and Terrestrial Rock Abrasion from Wind Tunnel and Field Studies

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.; Greeley, R.; Eddlemon, E.; Laity, J. E.; Meyer, C.; Phoreman, J.; White, B. R.

    2003-01-01

    Earth and Mars exhibit ventifacts, rocks that have been abraded by saltating sand. Previous theoretical and laboratory studies have determined abrasion susceptibilities of rocks as a function of sand type and impact angle and rock material strengths. For the last two years we have been engaged in wind tunnel and field studies to better understand the fundamental factors which control and influence rock abrasion and ventifact formation on Earth and Mars. In particular, we are examining: 1) What types of rocks (composition, texture, and shape) preferentially erode and what are the relative rates of one type vs. another? 2) What are the controlling factors of the aeolian sand cloud (flux, particle speed, surface roughness, etc) which favor rock abrasion?, 3) How do specific ventifact characteristics tie into their mode of formation and rock properties? We find several important factors: 1) Initial rock shape controls the rate of abrasion, with steeper faces abrading faster than shallower ones. The relationship is partly dependent on angle-dependent flux (proportional to sin[theta]) but exhibits additional non-linear effects from momentum transfer efficiency and rebound effects that vary with incidence angle. 2) Irregular targets with pits or grooves abrade at greater rates than targets with smooth surfaces, with indentations generally enlarging with time. Surfaces become rougher with time. 3) Targets also abrade via slope retreat, which is roughly dependent on the slope of the front face. The formation of basal sills is common, as observed on terrestrial and Martian ventifacts.

  7. Effect of banana on cold stress test & peak expiratory flow rate in healthy volunteers.

    PubMed

    Sarkar, C; Bairy, K L; Rao, N M; Udupa, E G

    1999-07-01

    The effect of banana on cold stress induced hypertension, peak expiratory flow rate and plasma ACE activity in healthy human volunteers was tested. Systolic blood pressure (P < 0.005), diastolic blood pressure (P < 0.025) and mean arterial blood pressure (P < 0.005) were significantly decreased during cold stress after banana treatment compared to controls subjected to cold stress. There was no significant changes in heart rate and peak expiratory flow rate but only significant decrease in plasma ACE activity after banana treatment. Banana decreased the rise of systolic blood pressure and diastolic blood pressure in healthy volunteers subjected to cold stress test without much effect on heart rate and peak expiratory flow rate. PMID:10709336

  8. Multi-wave ultrasonic Doppler method for measuring high flow-rates using staggered pulse intervals

    NASA Astrophysics Data System (ADS)

    Muramatsu, Ei; Murakawa, Hideki; Sugimoto, Katsumi; Asano, Hitoshi; Takenaka, Nobuyuki; Furuichi, Noriyuki

    2016-02-01

    The ultrasonic pulsed Doppler method (UDM) can obtain a velocity profile along the path of an ultrasonic beam. However, the UDM measurement volume is relatively large and it is known that the measurement volume affects the measurement accuracy. In this study, the effect of the measurement volume on velocity and flow rate measurements is analytically and experimentally evaluated. The velocities measured using UDM are considered to be ensemble-averaged values over the measurement volume in order to analyze the velocity error due to the measurement volume, while the flow rates are calculated from the integration of the velocity profile across the pipe. The analytical results show that the channel width, i.e. the spatial resolution along the ultrasonic beam axis, rather than the ultrasonic beam diameter, strongly influences the flow rate measurement. To improve the accuracy of the flow rate, a novel method using a multi-wave ultrasonic transducer consisting of two piezo-electric elements with different basic frequencies is proposed to minimize the size of the measurement volume in the near-wall region of a pipe flow. The velocity profiles in the near-wall region are measured using an 8 MHz sensor with a small diameter, while those far from the transducer are measured using a hollow 2 MHz sensor in the multi-wave transducer. The applicability of the multi-wave transducer was experimentally investigated using the water flow-rate calibration facility at the National Institute of Advanced Industrial Science and Technology (AIST). As a result, the errors in the flow rate were found to be below  -1%, while the multi-wave method is shown to be particularly effective for measuring higher flow rates in a large-diameter pipe.

  9. Effects of coil location and injection flow rate in an inductively coupled RF plasma torch

    NASA Astrophysics Data System (ADS)

    Wei, D.; Apelian, D.; Farouk, B.

    1985-07-01

    A numerical model has been developed to investigate the effects of central carrier gas flow rate and coil location in an inductively coupled RF plasma torch. Solution algorithm is based on the primitive variable formulation of the Navier-Stokes equations and includes a pseudo two-dimensional electromagnetic field model. Computational results have shown that with increasing carrier gas flow rate, the plasma plume is penetrated and the back flow due to the magnetic pumping effects is diminished. This facilitates the delivery of powder particles into the discharge region. However, the plasma plume is also disturbed significantly thus enhancing power loss.

  10. The effects of changes in flow rate on erosion volumes in young incising river systems

    NASA Astrophysics Data System (ADS)

    Day, S. S.; Gran, K. B.

    2010-12-01

    The effects of changes in flow rate on erosion volumes in young incising river systems Rainfall events, and the way in which water drains from the landscape after them, can have an impact on erosion rates in a river system. We are running a series of experiments to test how increased rate of flow either from rapid large rainfall events or more common events exacerbated by runoff can impact erosion in a watershed. These experiments will use a small basin (1 m^2) with a flat erodible bed. Water runs over the surface as overland flow and a stream network evolves following a single rapid base level drop. Sediment concentrations are measured every 10 minutes to track the volume of sediment leaving the basin. Topography is scanned with a high-resolution laser scanner at the beginning, end, and 5-10 times throughout each run. These scans will be used to both track volumetric sediment flux and determine spatially where erosion is occurring as the landscape evolves. Metrics including drainage density, stream length and width can be derived from the topographic scans. The water enters the basin as an even sheet flow from the top of the basin and flows to a narrow opening at the bottom of the tank. To test how changes to the flow rate impact basin evolution we will change the flow rate of each run. The rates will vary from 1 to 38 liters/minute. In addition, to test how changes in flow rate compare to changes in volume we will be varying the volume from 189 to 568 liters. There will be a total of 24 separate runs performed during the course of this experiment. This setup emulates the flat agricultural lands in southern Minnesota where rivers are actively evolving in response to a sudden base level drop on the Minnesota River. First order streams such as ravines and gullies incise into this flat landscape partly in response to overland flow draining toward the river. Changes to local hydrology, which cause water to be routed into these features more rapidly, may cause incision

  11. Controlling hydrophilicity of polymer film by altering gas flow rate in atmospheric-pressure homogeneous plasma

    NASA Astrophysics Data System (ADS)

    Kang, Woo Seok; Hur, Min; Lee, Jae-Ok; Song, Young-Hoon

    2014-03-01

    This paper reports on controlling the hydrophilicity of polyimide films using atmospheric-pressure homogeneous plasmas by changing only the gas flow rate. The gas flow changed the discharge atmosphere by mixing the feed gas with ambient air because of the particular geometry of the reactor developed for the study, and a low gas flow rate was found to be favorable because it generated abundant nitrogen or oxygen species that served as sources of hydrophilic functional groups over the polymer surface. After low-gas-flow plasma treatment, the polymer surface exhibited hydrophilic characteristics with increased surface roughness and enhanced chemical properties owing to the surface addition of functional groups. Without adding any reactive gases or requiring high plasma power and longer treatment time, the developed reactor with low-gas-flow operation offered effective and economical wettability control of polyimide films.

  12. Impact of gas flow rate on breakdown of filamentary dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Höft, H.; Becker, M. M.; Kettlitz, M.

    2016-03-01

    The influence of gas flow rate on breakdown properties and stability of pulsed dielectric barrier discharges (DBDs) in a single filament arrangement using a gas mixture of 0.1 vol. % O2 in N2 at atmospheric pressure was investigated by means of electrical and optical diagnostics, accompanied by fluid dynamics and electrostatics simulations. A higher flow rate perpendicular to the electrode symmetry axis resulted in an increased breakdown voltage and DBD current maximum, a higher discharge inception jitter, and a larger emission diameter of the discharge channel. In addition, a shift of the filament position for low gas flow rates with respect to the electrode symmetry axis was observed. These effects can be explained by the change of the residence time of charge carriers in the discharge region—i.e., the volume pre-ionization—for changed flow conditions due to the convective transport of particles out of the center of the gap.

  13. A measurement method of the flow rate in a pipe using a microphone array

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Beum; Kim, Yang-Hann

    2002-09-01

    A method of measuring the flow rate in a pipe is proposed. The method utilizes one-dimensional acoustic pressure signals that are generated by a loud speaker. A microphone array mounted flush with the inner pipe wall is used to measure the signals. A formula for the flow rate, which is a function of the change of wave number, is derived from a simple mathematical model of sound field in the pipe conveying a viscous fluid. The change of the wave number, which is one of the results caused by flow, is estimated from the recursive relation among the measured microphone array signals. Since measurement errors, due to extraneous measurement noise and mismatch of response characteristics between microphones, exist in the estimated flow rate, a method of compensating the errors is proposed. By using this measurement method, the flow rate can be obtained more accurately than that of our previous method. To verify applicability of the measurement method, numerical simulation and experiments are performed. The estimated flow rates are within 5% error bound. copyright 2002 Acoustical Society of America.

  14. Evaluation of the effect of transcutaneous electrical nerve stimulation (TENS) on whole salivary flow rate

    PubMed Central

    Pal-Singh, Mohit; Mathur, Hemant; Astekar, Sowmya; Gulati, Pranay; Lakhani, Shruta

    2015-01-01

    Background: Saliva plays a critical role in maintaining oral homeostasis; it modulates the ecosystem through lubrication of the alimentary bolus, protection against microorganisms, buffer and repair of the oral mucosa, and helps in dental re-mineralization. Various local and systemic factors such as medications, radiation therapy, systemic conditions, etc. can lead to reduction in salivary flow. A decrease in salivary function, known as Xerostomia, increases a patient’s risk for caries and other oral infections. Palliative management of Xerostomia includes wetting agents such as ice chips, drugs and saliva substitutes. Systemic agents stimulate salivary flow but often have unfavorable side effects. Newer modalities like transcutaneous electrical nerve stimulation (TENS), which has fewer side effects, have been used to stimulate salivary flow. The aim of the present study was to assess and evaluate the effect of TENS on whole salivary flow rates in healthy adult subjects. Study design: A total of 80 healthy adult subjects were enrolled in the study. Unstimulated and stimulated saliva (using TENS) was collected for 5 minutes and the mean salivary flow rates were calculated. Data obtained was analyzed using the SPSS (Statistical package for social sciences) version 15. Students ‘t’ test was employed for comparative analysis. Results: Sixty-five of the 80 subjects demonstrated an increase in the salivary flow rate on application of TENS. Twelve subjects demonstrated a mild reduction in the salivary flow rates. Seven subjects experienced transient mild twitching of facial musculature as side effects. Conclusion: Significant increase in salivary flow rates was observed on application of TENS with minimal or no side effects. Key words:Stimulated saliva, whole salivary flow, TENS. PMID:25810824

  15. Flow rates and warming efficacy with Hotline and Ranger blood/fluid warmers.

    PubMed

    Horowitz, Peter E; Delagarza, Miguel A; Pulaski, Jaime J; Smith, Robert A

    2004-09-01

    The heating capabilities of a water bath blood/fluid warmer, Hotline, have proven superior to those of other devices. The dry heat warmer Ranger has not previously been compared with the Hotline. We evaluated these devices in terms of flow rates and efficacy of warming. We delivered room temperature (21 degrees C) saline and 10 degrees C packed red blood cells (RBCs) by using 90 mm Hg (gravity equivalent) and 300 mm Hg bag pressure and various sizes of IV catheters. The outflow from each device was connected to an inline thermistor, and simultaneous measurements of outflow temperature and flow volume per minute were recorded. Additional data points were obtained with a roller pump that delivered flows of 1-6 L/h through each device. We calculated the effect of these flow rates and outflow temperatures on the mean body temperature (MBT) of a 70-kg patient. The Hotline and Ranger had similar flow rates at 90 and 300 mm Hg pressure infusion when studied with various sizes of IV catheters. Hotline was able to deliver warmer RBCs and saline at slower flow rates (1-4 L/h), but because changes in MBT were almost identical, there was no clinically important advantage, and almost no heat was transferred at these slower flow rates. At more rapid flow rates (>4 L/h), the Ranger warmed RBCs and saline better and produced smaller decreases in MBT than the Hotline. The use of the Hotline for rapid infusions, especially of cold RBCs, is not recommended because of low outflow temperatures and decreases in MBT that were three times larger than those seen with the Ranger. PMID:15333412

  16. Preparation of monodisperse polystyrene/silica core-shell nano-composite abrasive with controllable size and its chemical mechanical polishing performance on copper

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Wang, Haibo; Zhang, Zefang; Qin, Fei; Liu, Weili; Song, Zhitang

    2011-11-01

    Monodisperse silica-coated polystyrene (PS) nano-composite abrasives with controllable size were prepared via a two-step process. Monodisperse positively charged PS colloids were synthesized via polymerization of styrene by using a cationic initiator. In the subsequent coating process, silica formed shell on the surfaces of core PS particles via the ammonia-catalyzed hydrolysis and condensation of tetraethoxysilane. Neither centrifugation/water wash/redispersion cycle process nor surface modification or addition surfactant was needed in the whole process. The morphology of the abrasives was characterized by scanning electron microscope. Transmission electron microscope and energy dispersive X-ray analysis results indicated that silica layer was successfully coated onto the surfaces of PS particles. Composite abrasive has a core-shell structure and smooth surface. The chemical mechanical polishing performances of the composite abrasive and conventional colloidal silica abrasive on blanket copper wafers were investigated. The root mean square roughness decreases from 4.27 nm to 0.56 nm using composite abrasive. The PS/SiO2 core-shell composite abrasives exhibited little higher material removal rate than silica abrasives.

  17. Effect of Various Sugary Beverages on Salivary pH, Flow Rate, and Oral Clearance Rate amongst Adults.

    PubMed

    Hans, Rinki; Thomas, Susan; Garla, Bharat; Dagli, Rushabh J; Hans, Manoj Kumar

    2016-01-01

    Introduction. Diet is a major aetiological factor for dental caries and enamel erosion. This study was undertaken with the aim of assessing the effect of selected locally available beverages on salivary pH, flow rate, and oral clearance rate amongst adults. Materials and Method. This clinical trial comprised 120 subjects. Test beverages undertaken were pepsi, fruit drink, coffee, and sweetened milk. Statistical analysis was carried out using SPSS version 17. Descriptive statistics, one-way ANOVA, and post hoc Tukey's test were applied in the statistical tests. Results. It was found that salivary pH decreased for all the beverages immediately after consumption and the salivary flow rate increased after their consumption. The oral clearance rate of sweetened milk was found to be the least at 6.5 minutes and that of pepsi was found to be 13 minutes. However, the oral clearance rates of fruit drink and coffee were found to be equal at 15 minutes. Conclusion. Although it was found out that liquids cleared rapidly from the oral cavity, they had a significant cariogenic and erosive potential. Hence, it is always advised to minimise the consumption of beverages, especially amongst children and young adults to maintain a good oral health. PMID:27051556

  18. Effect of Various Sugary Beverages on Salivary pH, Flow Rate, and Oral Clearance Rate amongst Adults

    PubMed Central

    Hans, Rinki; Thomas, Susan; Garla, Bharat; Dagli, Rushabh J.

    2016-01-01

    Introduction. Diet is a major aetiological factor for dental caries and enamel erosion. This study was undertaken with the aim of assessing the effect of selected locally available beverages on salivary pH, flow rate, and oral clearance rate amongst adults. Materials and Method. This clinical trial comprised 120 subjects. Test beverages undertaken were pepsi, fruit drink, coffee, and sweetened milk. Statistical analysis was carried out using SPSS version 17. Descriptive statistics, one-way ANOVA, and post hoc Tukey's test were applied in the statistical tests. Results. It was found that salivary pH decreased for all the beverages immediately after consumption and the salivary flow rate increased after their consumption. The oral clearance rate of sweetened milk was found to be the least at 6.5 minutes and that of pepsi was found to be 13 minutes. However, the oral clearance rates of fruit drink and coffee were found to be equal at 15 minutes. Conclusion. Although it was found out that liquids cleared rapidly from the oral cavity, they had a significant cariogenic and erosive potential. Hence, it is always advised to minimise the consumption of beverages, especially amongst children and young adults to maintain a good oral health. PMID:27051556

  19. Improving Flow Response of a Variable-rate Aerial Application System by Interactive Refinement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experiments were conducted to evaluate response of a variable-rate aerial application controller to changing flow rates and to improve its response at correspondingly varying system pressures. System improvements have been made by refinement of the control algorithms over time in collaboration with ...

  20. Influence of flow rate on aerosol particle size distributions from pressurized and breath-actuated inhalers.

    PubMed

    Smith, K J; Chan, H K; Brown, K F

    1998-01-01

    Particle size distribution of delivered aerosols and the total mass of drug delivered from the inhaler are important determinants of pulmonary deposition and response to inhalation therapy. Inhalation flow rate may vary between patients and from dose to dose. The Andersen Sampler (AS) cascade impactor operated at flow rates of 30 and 55 L/min and the Marple-Miller Impactor (MMI) operated at flow rates of 30, 55, and 80 L/min were used in this study to investigate the influence of airflow rate on the particle size distributions of inhalation products. Total mass of drug delivered from the inhaler, fine particle mass, fine particle fraction, percentage of nonrespirable particles, and amount of formulation retained within the inhaler were determined by ultraviolet spectrophotometry for several commercial bronchodilator products purchased in the marketplace, including a pressurized metered-dose inhaler (pMDI), breath-actuated pressurized inhaler (BAMDI), and three dry powder inhalers (DPIs), two containing salbutamol sulphate and the other containing terbutaline sulphate. Varying the flow rate through the cascade impactor produced no significant change in performance of the pressurized inhalers. Increasing the flow rate produced a greater mass of drug delivered and an increase in respirable particle mass and fraction from all DPIs tested. PMID:10346666

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

    PubMed

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

    2016-04-01

    High and low flow rate respirable size selective samplers including the CIP10-R (10 l min(-1)), FSP10 (11.2 l min(-1)), GK2.69 (4.4 l min(-1)), 10-mm nylon (1.7 l min(-1)), and Higgins-Dewell type (2.2 l min(-1)) were compared via side-by-side sampling in workplaces for respirable crystalline silica measurement. Sampling was conducted at eight different occupational sites in the USA and five different stonemasonry sites in Ireland. A total of 536 (268 pairs) personal samples and 55 area samples were collected. Gravimetric analysis was used to determine respirable dust mass and X-ray diffraction analysis was used to determine quartz mass. Ratios of respirable dust mass concentration, quartz mass concentration, respirable dust mass, and quartz mass from high and low flow rate samplers were compared. In general, samplers did not show significant differences greater than 30% in respirable dust mass concentration and quartz mass concentration when outliers (ratio <0.3 or >3.0) were removed from the analysis. The frequency of samples above the limit of detection and limit of quantification of quartz was significantly higher for the CIP10-R and FSP10 samplers compared to low flow rate samplers, while the GK2.69 cyclone did not show significant difference from low flow rate samplers. High flow rate samplers collected significantly more respirable dust and quartz than low flow rate samplers as expected indicating that utilizing high flow rate samplers might improve precision in quartz measurement. Although the samplers did not show significant differences in respirable dust and quartz concentrations, other practical attributes might make them more or less suitable for personal sampling. PMID:26608952

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

    PubMed Central

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

    2016-01-01

    High and low flow rate respirable size selective samplers including the CIP10-R (10 l min−1), FSP10 (11.2 l min−1), GK2.69 (4.4 l min−1), 10-mm nylon (1.7 l min−1), and Higgins-Dewell type (2.2 l min−1) were compared via side-by-side sampling in workplaces for respirable crystalline silica measurement. Sampling was conducted at eight different occupational sites in the USA and five different stonemasonry sites in Ireland. A total of 536 (268 pairs) personal samples and 55 area samples were collected. Gravimetric analysis was used to determine respirable dust mass and X-ray diffraction analysis was used to determine quartz mass. Ratios of respirable dust mass concentration, quartz mass concentration, respirable dust mass, and quartz mass from high and low flow rate samplers were compared. In general, samplers did not show significant differences greater than 30% in respirable dust mass concentration and quartz mass concentration when outliers (ratio <0.3 or >3.0) were removed from the analysis. The frequency of samples above the limit of detection and limit of quantification of quartz was significantly higher for the CIP10-R and FSP10 samplers compared to low flow rate samplers, while the GK2.69 cyclone did not show significant difference from low flow rate samplers. High flow rate samplers collected significantly more respirable dust and quartz than low flow rate samplers as expected indicating that utilizing high flow rate samplers might improve precision in quartz measurement. Although the samplers did not show significant differences in respirable dust and quartz concentrations, other practical attributes might make them more or less suitable for personal sampling. PMID:26608952

  3. Effects of dose, flow rate, and bile acid on diclofenac disposition in the perfused rat liver.

    PubMed

    Uraki, Misato; Kawase, Atsushi; Matsushima, Yuka; Iwaki, Masahiro

    2016-06-01

    An in situ perfused rat liver system is useful for studying the hepatic disposition of drugs and their metabolites. However, the effects of the perfusion conditions on drug disposition are unclear. We examined the effects of conditions such as flow rate (13 or 26 mL/min) and bile acid on disposition of diclofenac (DF) as a model drug and DF metabolites [diclofenac-1-O-acyl glucuronide (DF-Glu) or 4'-hydroxydiclofenac (DF-4'OH)] in the absence of albumin. DF, DF-Glu, and DF-4'OH concentrations in the perfusate and cumulative amounts of DF-Glu excreted in bile were measured using high-performance liquid chromatography methods. DF in the perfusate was rapidly eliminated as the perfusate flow rate increased. The area under the plasma concentration-time curve from 0 to 60 min (AUC0-60) for DF-Glu and DF-4'OH in a perfusate containing bile acid was lower at a flow rate of 26 and 13 mL/min, respectively. The bile flow rate at 26 mL/min with 24 μM of bile acid in the perfusate was significantly higher (ca. 3.5 times) compared with that at 13 mL/min without bile acid. Cumulative biliary DF-Glu excretion was also dramatically affected by the flow rate and addition of bile acid. This study indicated that the flow rate and bile acid in the perfused rat liver were key factors for bile flow rate and DF, DF-Glu, and DF-4'OH disposition in the absence of albumin. PMID:25656736

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

    SciTech Connect

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

    2009-08-01

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

  5. A new dimension to conservative dentistry: Air abrasion

    PubMed Central

    Hegde, Vivek S; Khatavkar, Roheet A

    2010-01-01

    Air abrasion dentistry has evolved over a period of time from a new concept of an alternative means of cavity preparation to an essential means of providing a truly conservative preparation for preservation of a maximal sound tooth structure. The development of bonded restorations in combination with air abrasion dentistry provides a truly minimal intervention dentistry. This article reviews the development of air abrasion, its clinical uses, and the essential accessories required for its use. PMID:20582212

  6. Process For Controlling Flow Rate Of Viscous Materials Including Use Of Nozzle With Changeable Openings

    DOEpatents

    Ellingson, William A.; Forster, George A.

    1999-11-02

    Apparatus and a method for controlling the flow rate of viscous materials through a nozzle includes an apertured main body and an apertured end cap coupled together and having an elongated, linear flow channel extending the length thereof. An end of the main body is disposed within the end cap and includes a plurality of elongated slots concentrically disposed about and aligned with the flow channel. A generally flat cam plate having a center aperture is disposed between the main body and end cap and is rotatable about the flow channel. A plurality of flow control vane assemblies are concentrically disposed about the flow channel and are coupled to the cam plate. Each vane assembly includes a vane element disposed adjacent the end of the flow channel. Rotation of the cam plate in a first direction causes a corresponding rotation of each of the vane elements for positioning the individual vane elements over the aperture in the end cap blocking flow through the flow channel, while rotation in an opposite direction removes the vane elements from the aperture and positions them about the flow channel in a nested configuration in the full open position, with a continuous range of vane element positions available between the full open and closed positions.

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

    PubMed Central

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

    2015-01-01

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

  8. Mechanism for measurement of flow rate of cerebrospinal fluid in hydrocephalus shunts.

    PubMed

    Rajasekaran, Sathish; Kovar, Spencer; Qu, Peng; Inwald, David; Williams, Evan; Qu, Hongwei; Zakalik, Karol

    2014-01-01

    The measurement of the flow rate of cerebrospinal fluid (CSF) or existence of CSF flow inside the shunt tube after shunt implant have been reported as tedious process for both patients and doctors; this paper outlines a potential in vitro flow rate measurement method for CSF in the hydrocephalus shunt. The use of implantable titanium elements in the shunt has been proposed to allow for an accurate temperature measurement along the shunt for prediction of CSF flow rate. The CSF flow velocity can be deduced by decoupling the thermal transfer in the measured differential time at a pair of measurement spots of the titanium elements. Finite element analyses on the fluidic and thermal behaviors of the shunt system have been conducted. Preliminary bench-top measurements on a simulated system have been carried out. The measured flow rates, ranging from 0.5 mm/sec to 1.0 mm/sec, which is clinically practical, demonstrate good agreements with the simulation results. PMID:25570411

  9. Colloidal asphaltene deposition in laminar pipe flow: Flow rate and parametric effects

    NASA Astrophysics Data System (ADS)

    Hashmi, S. M.; Loewenberg, M.; Firoozabadi, A.

    2015-08-01

    Deposition from a suspended phase onto a surface can aversely affect everyday transport processes on a variety of scales, from mineral scale corrosion of household plumbing systems to asphaltene deposition in large-scale pipelines in the petroleum industry. While petroleum may be a single fluid phase under reservoir conditions, depressurization upon production often induces a phase transition in the fluid, resulting in the precipitation of asphaltene material which readily aggregates to the colloidal scale and deposits on metallic surfaces. Colloidal asphaltene deposition in wellbores and pipelines can be especially problematic for industrial purposes, where cleanup processes necessitate costly operational shutdowns. In order to better understand the parametric dependence of deposition which leads to flow blockages, we carry out lab-scale experiments under a variety of material and flow conditions. We develop a parametric scaling model to understand the fluid dynamics and transport considerations governing deposition. The lab-scale experiments are performed by injecting precipitating petroleum fluid mixtures into a small metal pipe, which results in deposition and clogging, assessed by measuring the pressure drop across the pipe. Parametric scaling arguments suggest that the clogging behavior is determined by a combination of the Peclet number, volume fraction of depositing material, and the volume of the injection itself.

  10. Time decay rates for the equations of the compressible heat-conductive flow through porous media

    NASA Astrophysics Data System (ADS)

    Chen, Qing; Tan, Zhong; Wu, Guochun

    2015-11-01

    We consider the time decay rates of smooth solutions to the Cauchy problem for the equations of the compressible heat-conductive flow through porous media. We prove the global existence and uniqueness of the solutions by the standard energy method. Moreover, we establish the optimal decay rates of the solution as well as its higher-order spatial derivatives. And the damping effect on the time decay rates of the solution is studied in detail.

  11. Control of skin blood flow, sweating, and heart rate - Role of skin vs. core temperature

    NASA Technical Reports Server (NTRS)

    Wyss, C. R.; Brengelmann, G. L.; Johnson, J. M.; Rowell, L. B.; Niederberger, M.

    1974-01-01

    A study was conducted to generate quantitative expressions for the influence of core temperature, skin temperature, and the rate of change of skin temperature on sweat rate, skin blood flow, and heart rate. A second goal of the study was to determine whether the use of esophageal temperature rather than the right atrial temperature as a measure of core temperature would lead to different conclusions about the control of measured effector variables.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  13. The dollars and sense of selecting abrasion-resistant materials

    SciTech Connect

    Jackson, D.

    1988-05-01

    Sliding abrasion and impact damage affect mine and plant operating costs on a month-to-month, or, in some cases, day-to-day basis. Modern technology has given us the tools necessary to fight abrasion on every front - materials and techniques that are cost-effective, long-lasting, and easy to use. An inspection of abrasion-resistant materials and processes - metals; ceramics; sprayable and trowelable compounds; polyethylene; urethane; rubber; epoxy - may well provide information that could help improve your company's balance sheet. The following is a compilation of product releases, literature, and manuals offered by manufacturers of abrasion-resistant materials.

  14. Fluvial erosion of physically modeled abrasion-dominated slot canyons

    NASA Astrophysics Data System (ADS)

    Carter, Carissa L.; Anderson, Robert S.

    2006-11-01

    Abrasion-dominated fluvial erosion generates slot canyons in massive bedrock with intricately undulating walls. Flows in slot canyons are unusual in that the walls comprise a significant portion of the wetted perimeter of the flow during geomorphically effective floods. In Wire Pass, Utah, the upper Paria River incises through massive, crossbedded Navajo Sandstone. Incision in Wire Pass and related slots occurs only during flash floods; paleoflood debris indicates that the width/depth ratios of these flows are at times as low as 1:1. Submeter resolution field mapping of a 20-m length of Wire Pass shows that the wall morphology is a complicated combination of in-phase (meander-like) and out-of-phase (pinch and swell) undulations. In order to investigate evolution of slot canyons and the influence of their wall shapes on flow dynamics, we recorded the evolution of four distinct canyon wall morphologies in a 2.4 m flume box at the St. Anthony Falls Laboratory. In a substrate consisting of ˜ 3:2 mixtures of F110 sand and Plaster of Paris, we molded canyons with in-phase and out-of-phase undulations, and wide (6.5 cm) and narrow (4 cm) straight initial wall profiles. Discharges ranged from 1.4 L/s to 2.9 L/s, and wall and bed morphology were measured at 5 h intervals at 0.5 cm resolution. Results show efficient back-eddy erosion in the undulating canyon walls and related erosional bedforms in all channels created by vortices in the flow. Maximum filaments of velocity are depressed and asymmetric, and the implied shear stress distribution varied in space and time on the channel beds. Flow width/depth ratios strongly influence the flow structure and distribution of shear stress in a slot and appear to be a factor in dictating whether a bedrock channel widens its walls or incises its bed.

  15. The effect on human salivary flow rate of the temperature of a gustatory stimulus.

    PubMed

    Dawes, C; O'Connor, A M; Aspen, J M

    2000-11-01

    In the first study, whole saliva was collected from ten adults during stimulation with sour, carbonated, sweet and water stimuli in the form of 5-ml of ice at about -10 degrees C or of liquids at 0, 8, 20 or 37 degrees C. Parotid saliva was also collected in response to ice or infusion into the mouth of the liquids at different temperatures. Another group of ten adults also collected whole saliva in response to water at 20 degrees C, with or without the presence in the mouth of an acrylic cube of dimensions similar to those of the ice. In a second study, 20 adults collected whole saliva in response to stimulation with 5 ml of water and of an astringent stimulus at 0, 8, 37 and 70 degrees C. In the first study, flow rates fell in the order sour, carbonated, sweet and water and flow rates in response to stimuli in the form of ice were very significantly higher than in response to the corresponding liquids at the four different temperatures. With the sour stimulus, liquids at 0 and 8 degrees C elicited higher flow rates than liquids at 20 or 37 degrees C. Although the presence in the mouth of the acrylic block increased the flow rate of whole saliva, the increase was only about 30% of that achieved with ice. In the second study, the astringent stimulus was a more effective salivary stimulus than water; flow rates were significantly higher in response to liquids at 0 and 8 degrees C than at the higher temperatures and flow rates in response to liquids at 37 degrees C were significantly lower than with the other temperatures. In summary, stimuli in the form of ice were the most effective and liquids at 37 degrees C were least effective in stimulating salivary flow. PMID:11000382

  16. Transport rates of a class of two-dimensional maps and flows

    NASA Astrophysics Data System (ADS)

    Rom-Kedar, V.

    1990-07-01

    A method is developed for estimating the transport rates of phase space areas for a class of two-dimensional diffeomorphisms and flows. The class of diffeomorphisms we considered are defined by the topological structure of their stable and unstable manifolds, and hence are universal. We show how to estimate the transport rates for a class of diffeomorphisms found by Easton and for an extension of this class of diffeomorphisms which is found via a “perturbation” of the topology of the stable and unstable manifolds. This is done by introducing symbolic dynamics and transfer matrices which in turn relate transport phenomena in phase space to Markov processes in a precise manner. In addition to the transport rates, we use the transfer matrices to obtain estimates for the topological entropy, averaged stretching rates, and the elongation rate of the unstable manifold. The flows we consider are two-dimensional, time-periodic flows which can be reduced via Poincaré section to the extended family of maps. We develop an analytical method, based on Chirikov's Whisker map, to classify a given flow according to the structure of its manifolds in its Poincaré section. This allows the techniques developed here for maps to be directly applied to time-periodic flows.

  17. An in vivo assessment of the influence of needle gauges on endodontic irrigation flow rate

    PubMed Central

    Gopikrishna, Velayutham; Sibi, Swamy; Archana, Durvasulu; Pradeep Kumar, Angabakkam Rajasekaran; Narayanan, Lakshmi

    2016-01-01

    Aim: The aim of this clinical study was to assess the influence of irrigation needle gauge on endodontic irrigation flow rates. Settings and Design: In vivo assessment. Materials and Methods: Five specialist endodontists performed intracanal irrigation procedures on 50 mesiobuccal canal of mandibular first molars using three different irrigation needle gauges. Data of time taken for irrigation was recorded by an irrigation testing system and analyzed using independent sample “T” test and one-way analysis of variance (ANOVA) test. The level of significance was set at P < 0.05. Statistical Analysis Used: The following tests were used for the statistical analysis: Independent sample “T” test, one-way ANOVA test, and post hoc multiple comparison was carried out using Tukey's honest significant difference (HSD) test using Statistical Package for the Social Sciences (SPSS) version 16 for Windows. Results: The average flow rate of 26 gauge was 0.27 mLs−1, of 27 gauge was 0.19 mLs−1, and of 30 gauge was 0.09 mls−1. There was statistical significance among the gauges (P < 0.001). 26 gauge had highest flow rate when compared with other groups followed by 27 gauge and 30 gauge respectively. The operator variability for flow rate of three endodontic irrigation needle gauges (26 gauge, 27 gauge, and 30 gauge) was found to be not significant. Conclusions: Needle gauge has significant influence on endodontic irrigation flow rate. PMID:27099430

  18. Pebble Jammed in Rock Abrasion Tool

    NASA Technical Reports Server (NTRS)

    2004-01-01

    After the rock abrasion tool on NASA's Mars Exploration Rover Opportunity stopped working on sol 199 (Aug. 15, 2004), rover operators used the panoramic camera to take this image the next day for help in diagnosing the problem. The tool was closer than the camera could focus on sharply, but the image does show a dark spot just left of center, which engineers have determined is likely to be a pebble jammed between the cutting-blade rotor and the wire-brush rotor. If that diagnosis is confirmed by further analysis, the tool will likely be commanded to turn the rotors in reverse to release the pebble.

  19. Mars Pathfinder Wheel Abrasion Experiment Ground Test

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Siebert, Mark W.

    1998-01-01

    The National Aeronautics and Space Administration (NASA) sent a mission to the martian surface, called Mars Pathfinder. The mission payload consisted of a lander and a rover. The primary purpose of the mission was demonstrating a novel entry, descent, and landing method that included a heat shield, a parachute, rockets, and a cocoon of giant air bags. Once on the surface, the spacecraft returned temperature measurements near the Martian surface, atmosphere pressure, wind speed measurements, and images from the lander and rover. The rover obtained 16 elemental measurements of rocks and soils, performed soil-mechanics, atmospheric sedimentation measurements, and soil abrasiveness measurements.

  20. Skeletal blood flow, iliac histomorphometry, and strontium kinetics in osteoporosis: a relationship between blood flow and corrected apposition rate

    SciTech Connect

    Reeve, J.; Arlot, M.; Wootton, R.; Edouard, C.; Tellez, M.; Hesp, R.; Green, J.R.; Meunier, P.J.

    1988-06-01

    In 20 untreated patients with idiopathic or postmenopausal osteoporosis, kinetic studies of skeletal blood flow (using /sup 18/F) and bone turnover (using /sup 85/Sr) were combined with dynamic histomorphometry performed on transiliac biopsies taken within 6 weeks of each other. In 8 patients the combined studies were repeated after treatment. A further 5 patients were studied only while receiving treatment. As expected, skeletal blood flow measured by /sup 18/F correlated with an index of /sup 85/Sr uptake into the exchangeable pools of bone. Additionally and independently, skeletal blood flow correlated with an index of the work rate of the osteoblasts in each multicellular unit of bone (the corrected apposition rate of Parfitt). These correlations were statistically significant in both the untreated patients (P less than 0.05) and the whole group (P less than 0.001). Further indices related to bone turnover at the level of the skeleton as a whole were significantly associated with skeletal blood flow only in the combined group.

  1. Effects of shear rate, confinement, and particle parameters on margination in blood flow.

    PubMed

    Mehrabadi, Marmar; Ku, David N; Aidun, Cyrus K

    2016-02-01

    The effects of flow and particle properties on margination of particles in red blood cell (RBC) suspensions is investigated using direct numerical simulation (DNS) of cellar blood flow. We focus on margination of particles in the flow of moderately dense suspensions of RBCs. We hypothesize that margination rate in nondilute suspensions is mainly driven by the RBC-enhanced diffusion of marginating particles in the RBC-filled region. We derive a scaling law for margination length in a straight channel. Margination length increases cubically with channel height and is independent of shear rate. We verify this scaling law for margination length by DNS of flowing RBCs and marginating particles. We also show that rigidity and size both lead to particle margination with rigidity having a more significant effect compared to size within the range of parameters in this study. PMID:26986415

  2. Effects of shear rate, confinement, and particle parameters on margination in blood flow

    NASA Astrophysics Data System (ADS)

    Mehrabadi, Marmar; Ku, David N.; Aidun, Cyrus K.

    2016-02-01

    The effects of flow and particle properties on margination of particles in red blood cell (RBC) suspensions is investigated using direct numerical simulation (DNS) of cellar blood flow. We focus on margination of particles in the flow of moderately dense suspensions of RBCs. We hypothesize that margination rate in nondilute suspensions is mainly driven by the RBC-enhanced diffusion of marginating particles in the RBC-filled region. We derive a scaling law for margination length in a straight channel. Margination length increases cubically with channel height and is independent of shear rate. We verify this scaling law for margination length by DNS of flowing RBCs and marginating particles. We also show that rigidity and size both lead to particle margination with rigidity having a more significant effect compared to size within the range of parameters in this study.

  3. Studies with sample conductivity, insertion rates, and particle deflection in a continuous flow electrophoresis system

    NASA Technical Reports Server (NTRS)

    Williams, G., Jr.

    1982-01-01

    The continuous flow electrophoresis system makes electrophoresis possible in a free-flowing film of aqueous electrolyte medium. The sample continuously enters the electrolyte at the top of the chamber and is subjected to the action of a lateral dc field. This divides the sample into fractions since each component has a distinctive electrophoretic mobility. Tests were made using monodisperse polystyrene latex microspheres to determine optimum sample conductivity, insertion rates and optimum electric field applications as baseline data for future STS flight experiments. Optimum sample flow rates for the selected samples were determined to be approximately 26 micro-liters/min. Experiments with samples in deionized water yielded best results and voltages in the 20 V/cm to 30 V/cm range were optimum. Deflections of formaldehyde fixed turkey and bovine erythrocytes were determined using the continuous flow electrophoresis system. The effects of particle interactions on sample resolution and migration in the chamber was also evaluated.

  4. Turbulent transport measurements in a cold model of GT-burner at realistic flow rates

    NASA Astrophysics Data System (ADS)

    Gobyzov, Oleg; Chikishev, Leonid; Lobasov, Alexey; Sharaborin, Dmitriy; Dulin, Vladimir; Bilsky, Artur; Tsatiashvili, Vakhtang; Avgustinovich, Valery; Markovich, Dmitriy

    2016-03-01

    In the present work simultaneous velocity field and passive admixture concentration field measurements at realistic flow-rates conditions in a non-reacting flow in a model of combustion chamber with an industrial mixing device are reported. In the experiments for safety reasons the real fuel (natural gas) was replaced with neon gas to simulate stratification in a strongly swirling flow. Measurements were performed by means of planar laser-induced fluorescence (PLIF) and particle image velocimetry technique (PIV) at Reynolds number, based on the mean flow rate and nozzle diameter, ≈300 000. Details on experimental technique, features of the experimental setup, images and data preprocessing procedures and results of performed measurements are given in the paper. In addition to the raw velocity and admixture concentration data in-depth evaluation approaches aimed for estimation of turbulent kinetic energy (TKE) components, assessment of turbulent Schmidt number and analysis of the gradient closure hypothesis from experimental data are presented in the paper.

  5. Model for charge/discharge-rate-dependent plastic flow in amorphous battery materials

    NASA Astrophysics Data System (ADS)

    Khosrownejad, S. M.; Curtin, W. A.

    2016-09-01

    Plastic flow is an important mechanism for relaxing stresses that develop due to swelling/shrinkage during charging/discharging of battery materials. Amorphous high-storage-capacity Li-Si has lower flow stresses than crystalline materials but there is evidence that the plastic flow stress depends on the conditions of charging and discharging, indicating important non-equilibrium aspects to the flow behavior. Here, a mechanistically-based constitutive model for rate-dependent plastic flow in amorphous materials, such as LixSi alloys, during charging and discharging is developed based on two physical concepts: (i) excess energy is stored in the material during electrochemical charging and discharging due to the inability of the amorphous material to fully relax during the charging/discharging process and (ii) this excess energy reduces the barriers for plastic flow processes and thus reduces the applied stresses necessary to cause plastic flow. The plastic flow stress is thus a competition between the time scales of charging/discharging and the time scales of glassy relaxation. The two concepts, as well as other aspects of the model, are validated using molecular simulations on a model Li-Si system. The model is applied to examine the plastic flow behavior of typical specimen geometries due to combined charging/discharging and stress history, and the results generally rationalize experimental observations.

  6. Debris-flow deposits and watershed erosion rates near southern Death Valley, CA, United States

    USGS Publications Warehouse

    Schmidt, K.M.; Menges, C.M.

    2003-01-01

    Debris flows from the steep, granitic hillslopes of the Kingston Range, CA are commensurate in age with nearby fluvial deposits. Quaternary chronostratigraphic differentiation of debris-flow deposits is based upon time-dependent characteristics such as relative boulder strength, derived from Schmidt Hammer measurements, degree of surface desert varnish, pedogenesis, and vertical separation. Rock strength is highest for Holocene-aged boulders and decreases for Pleistocene-aged boulders weathering to grus. Volumes of age-stratified debris-flow deposits, constrained by deposit thickness above bedrock, GPS surveys, and geologic mapping, are greatest for Pleistocene deposits. Shallow landslide susceptibility, derived from a topographically based GIS model, in conjunction with deposit volumes produces watershed-scale erosion rates of ???2-47 mm ka-1, with time-averaged Holocene rates exceeding Pleistocene rates. ?? 2003 Millpress.

  7. Major salivary gland flow rates in young and old, generally healthy African Americans and whites.

    PubMed

    Jones, R E; Ship, J A

    1995-02-01

    Saliva is essential to maintain and preserve oral health. Previous studies of primarily white populations demonstrated that salivary gland flow rates are age-stable in healthy adults, but there are little data on African Americans of different ages. The purpose of this study was to determine if there is a relationship between age, gender, and race in unstimulated and stimulated parotid and submandibular salivary gland flow rates and to evaluate subjective responses to questions regarding salivary dysfunction. Sixty generally healthy, middle socioeconomic class African Americans and whites between the ages of 20 to 40 and 60 to 80 years were evaluated. The results indicate, in general, that objective and subjective measurements of major salivary gland flow rates are independent of age, gender, and race. Further studies are required using larger populations. These results suggest that signs and symptoms of dry mouth in the elderly regardless of race or gender should not be considered a normal sequela of aging. PMID:7897685

  8. Assessing effusion rate of lava flows from thermal structure: theoretical analysis and lab-scale experiments

    NASA Astrophysics Data System (ADS)

    Garel, Fanny; Kaminski, Edouard; Tait, Stephen; Limare, Angela

    2010-05-01

    Management of effusive volcanic crises has to be based on the quantitative interpretation of flow monitoring. An important issue is the ability to predict where the flow will go, and when it will stop. Geophysical fluid dynamics shows that the spreading of lava flows is mainly controlled by its rheology and the eruptive mass flux. Hence the key question is how to evaluate them during the eruption (rather than afterwards). A relationship between the surface structure temperature and the eruption rate is likely to exist, based on the first-order argument that higher eruption rates should correspond to larger energy radiated by a lava flow. A theoretical formula combining some empirical parameters was developed by Harris and co-workers (review in Harris et al., 2007) and is used to estimate lava flow rate from satellite. However, the theoretical grounds of this technique, as well as its domain of validity, remain questioned. Here we propose a systematic theoretical study to help to define the validity domain of this approach and to investigate whether or not it can be refined and/or modify to better assess flow rates. We chose in our approach to study at lab-scale a flow with a rheology simpler than that of the natural lava, but taking into account all the complexity of the cooling process at the surface of the flow, by radiation and convection. We used fully controlled experimental parameters, especially the cooling conditions, the flux rate and geometry of the flow. The spreading geometry is the one of an axisymmetric viscous gravity current of newtonian viscosity (Huppert, 1982). For a given enthalpy content, the coupled cooling/spreading processes are characterized by two dimensionless numbers. A first one quantifies the efficiency of the surface cooling compared to the heat advected in the flow. The second one quantifies the relative efficiency of radiative and convective surface cooling. We identify different stages of cooling as a function of these numbers and

  9. Glacial erosion and bedrock properties in NW Scotland: Abrasion and plucking, hardness and joint spacing

    NASA Astrophysics Data System (ADS)

    Krabbendam, Maarten; Glasser, Neil F.

    2011-07-01

    Subglacial erosion beneath glaciers occurs predominantly by abrasion and plucking, producing distinct erosional forms. The controls on the relative importance of abrasion vs. plucking are poorly understood. On the one hand, glacial conditions that favour or suppress cavity formation (ice velocity, ice thickness, and water pressure) are thought to favour plucking or abrasion, respectively. Conversely, bedrock properties are also known to control landforms, but this has rarely been analysed quantitatively. In this study we compare landforms and bedrock properties of sandstone and quartzite at the bed of a palaeo-ice stream near Ullapool in NW Scotland. The boundary between the rock types is at right angles to the westward palaeo-ice flow, and palaeoglacial conditions on both rock types were similar. We report quantitative parameters for bedrock properties (Schmidt hammer hardness and joint spacing) and use morphometric parameters to analyse the landforms. Torridon sandstone is soft but thick-bedded and with a wide joint spacing. Erosional bedforms include roche moutonnées with smoothed tops and concave stoss sides, whalebacks, and elongate p-forms, indicating a high proportion of abrasion over plucking. Cambrian quartzite is hard but thin-bedded with narrow joint spacing. Erosional landforms are angular to subangular with abundant plucked lee faces, suggesting a high proportion of plucking over abrasion. Hardness and joint spacing thus exert a strong control on subglacial erosional landforms and the mechanisms that formed them. Thus glacial conditions (ice velocity, ice thickness) can only be inferred from glacial erosional landforms if the effects of bedrock properties of the substrate are considered.

  10. Flow rate self-sensing of a pump with double piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Zhang, Zhonghua; Kan, Junwu; Wang, Shuyun; Wang, Hongyun; Wen, Jianming; Ma, Zehui

    2013-12-01

    According to the method of segmenting electrode, the flow rate self-sensing of a conventional piezoelectric pump with the actuators of double diaphragms is presented in this paper. The novel pump is characterized by the simultaneous function of fluid transportation and the flow rate self-testing through only one piezoelectric element. The analysis indicates that direct and converse piezoelectric effect can be concurrently applied to obtain the simultaneous function through dividing the electrode of the piezoelectric element into driving unit and sensing unit. With two commercialized segmented-electrode piezoelectric diaphragms, a prototype pump is fabricated with the size of 65 mm×40 mm×12 mm and tested according to the frequency characteristics at a fixed driving voltage and the driving voltage characteristics at a fixed frequency. The results show that sensing voltages of diaphragms are increased or decreased with the change of the flow rate as a function of frequency. When the flow rate reaches the maximum value of 45.98 ml/min at 15 Hz, outlet/inlet sensing voltages also reach maximum values of 6.80 Vpp and 19.4 Vpp, respectively. It demonstrates that the pump itself could accurately reflect the optimal frequency through monitoring outlet/inlet sensing voltages. The testing results indicate the good linear relationship between outlet/inlet sensing voltages and the flow rate as a function of driving voltage. Therefore, both theoretical analysis and experiments have proved that flow rate self-sensing can be realized for the piezoelectric pumps with double actuators through segmenting their electrode. Moreover, if any electrode of double piezoelectric actuators is segmented, the pump can obtain the complete self-sensing function.

  11. Effect of flow rate on loss mechanisms in a backswept centrifugal impeller

    NASA Astrophysics Data System (ADS)

    Farge, Talib Z.; Johnson, Mark W.

    1992-06-01

    Detailed measurements of the three velocity components, total, and static pressures on five measurement planes without a low speed shrouded backswept centrifugal impeller are presented. A comparison is made between the design flowfield and the flowfields for both below and above design flow rates. The flow is dominated by a passage vortex that rotates in the opposite direction to the impeller. This vortex develops in the inducer, is strongest in the axial to radial bend, and then decays toward the outlet. The vortex is also most prominent at the lowest flow rate and is responsible for stabilizing the shroud boundary layer and hence reducing the large losses associated with the separation of this boundary layer in radial impellers. At the outlet, the wake is located on the shroud at all flow rates, but tends to be spread more evenly across the shroud than is the case in a radial machine. The impeller efficiency is also generally found to be spread more evenly across the shroud than is the case in a radial machine. The impeller efficiency is also generally found to be higher at lower flow rates in contrast to observations for radial impellers.

  12. Quantifying the flow rate of the Deepwater Horizon Macondo Well oil spill

    NASA Astrophysics Data System (ADS)

    Camilli, R.; Bowen, A.; Yoerger, D. R.; Whitcomb, L. L.; Techet, A. H.; Reddy, C. M.; Sylva, S.; Seewald, J.; di Iorio, D.; Whoi Flow Rate Measurement Group

    2010-12-01

    The Deepwater Horizon blowout in the Mississippi Canyon block 252 of the Gulf of Mexico created the largest recorded offshore oil spill. The well outflow’s multiple leak sources, turbulent multiphase flow, tendency for hydrate formation, and extreme source depth of 1500 m below the sea surface complicated the quantitative estimation of oil and gas leakage rates. We present methods and results from a U.S. Coast Guard sponsored flow assessment study of the Deepwater Horizon’s damaged blow out preventer and riser. This study utilized a remotely operated vehicle equipped with in-situ acoustic sensors (a Doppler sonar and an imaging multibeam sonar) and isobaric gas-tight fluid samplers to measure directly outflow from the damaged well. Findings from this study indicate oil release rates and total release volume estimates that corroborate estimates made by the federal government’s Flow Rate Technical Group using non-acoustic techniques. The acoustic survey methods reported here provides a means for estimating fluid flow rates in subsurface environments, and are potentially useful for a diverse range of oceanographic applications. Photograph of the Discoverer Enterprise burning natural gas collected from the Macondo well blowout preventer during flow measurement operations. Copyright Wood Hole Oceanographic Institution.

  13. Research and realization of ultrasonic gas flow rate measurement based on ultrasonic exponential model.

    PubMed

    Zheng, Dandan; Hou, Huirang; Zhang, Tao

    2016-04-01

    For ultrasonic gas flow rate measurement based on ultrasonic exponential model, when the noise frequency is close to that of the desired signals (called similar-frequency noise) or the received signal amplitude is small and unstable at big flow rate, local convergence of the algorithm genetic-ant colony optimization-3cycles may appear, and measurement accuracy may be affected. Therefore, an improved method energy genetic-ant colony optimization-3cycles (EGACO-3cycles) is proposed to solve this problem. By judging the maximum energy position of signal, the initial parameter range of exponential model can be narrowed and then the local convergence can be avoided. Moreover, a DN100 flow rate measurement system with EGACO-3cycles method is established based on NI PCI-6110 and personal computer. A series of experiments are carried out for testing the new method and the measurement system. It is shown that local convergence doesn't appear with EGACO-3cycles method when similar-frequency noises exist and flow rate is big. Then correct time of flight can be obtained. Furthermore, through flow calibration on this system, the measurement range ratio is achieved 500:1, and the measurement accuracy is 0.5% with a low transition velocity 0.3 m/s. PMID:26821309

  14. Mars Exploration Rovers' Rock Abrasion Tool

    NASA Astrophysics Data System (ADS)

    Gorevan, S.; Myrick, T.; Davis, K.; Ji, J.; Bartlett, P.; Mukherjee, S.; Arafat, T.

    2003-04-01

    Each of the twin 2003 Mars Exploration Rovers will be equipped with a Rock Abrasion Tool (RAT) designed and tested by Honeybee Robotics. The RAT is a robotic grinding tool and science instrument about the size of a soda can and weighing less than 690 grams that is carried by the robotic arm or Instrument Deployment Device (IDD) of the rover. The primary purpose of the RAT is to remove the dust and surface rind from Mars rock targets to reveal the underlying petrographic features. After the RAT is placed and preloaded against the target rock by the IDD, all operations of the RAT are performed autonomously. Using three small motors to drive the rotation, revolve and z-axis subassemblies the RAT removes a 45 mm diameter, 5 mm deep patch of rock. The RAT has a resin-bonded diamond abrasion wheel and two brushes to provide a clean observation surface for the three surface instruments - APXS, Microscopic Imager and Moessbauer Spectrometer. Detailed design and operation descriptions, as well as recent qualification and operational testing results will be presented.

  15. Microstructural effects in abrasive wear. Quarterly progress report, January 1-June 1, 1980

    SciTech Connect

    Fiore, N.F.; Kosel, T.H.; Channagiri, M.; Desai, V.; Fulcher, J.; Shetty, H.R.

    1980-06-01

    Research aimed at establishing quantitative relationships between microstructure and wear resistance of highly alloyed materials is described including high-Cr white irons and experimental Co-base and Ni-base powder metallurgy (PM) alloys now used or potentially to be used in coal mining, handling and gasification. The specific types of wear under study are low-stress abrasion and gouging wear encountered in mining, coal conversion and transfer applications. Research has concentrated on the investigation of wear in Co-base PM alloys No. 19 and No. 6, which have been sintered to provide different carbide sizes at the same volume fraction in each respective alloy. Low-stress abrasion tests using Al/sub 2/O/sub 3/ abrasive have been completed on Alloy No. 19 and the results show a monotonic decrease in wear rate with increasing size. A series of single-point scratch test simulations of abrasive wear mechanisms has been initiated, and these tests provide valuable insights into material removal processes in the Co-base alloys.

  16. The cooling rates of pahoehoe flows: The importance of lava porosity

    NASA Technical Reports Server (NTRS)

    Jones, Alun C.

    1993-01-01

    Many theoretical models have been put forward to account for the cooling history of a lava flow; however, only limited detailed field data exist to validate these models. To accurately model the cooling of lava flows, data are required, not only on the heat loss mechanisms, but also on the surface skin development and the causes of differing cooling rates. This paper argues that the cause of such variations in the cooling rates are attributed, primarily, to the vesicle content and degassing history of the lava.

  17. The rate dependence of the saturation flow stress of Cu and 1100 Al

    SciTech Connect

    Preston, D.L.; Tonks, D.L.; Wallace, D.C.

    1991-01-01

    The strain-rate dependence of the saturation flow stress of OFHC Cu and 1100 Al from 10{sup {minus}3}s{sup {minus}1} to nearly to 10{sup 12}s{sup {minus}1} is examined. The flow stress above 10{sup 9}s{sup {minus}1} is estimated using Wallace's theory of overdriven shocks in metals. A transition to the power-law behavior {Psi} {approximately} {tau}{sub s}{sup 5} occurs at a strain rate of order 10{sup 5}s{sup {minus}1}. 10 refs., 2 figs.

  18. Method of measuring the mass flow rate of a substance entering a cocurrent fluid stream

    DOEpatents

    Cochran, Jr., Henry D.

    1978-04-11

    This invention relates to an improved method of monitoring the mass flow rate of a substance entering a cocurrent fluid stream. The method very basically consists of heating equal sections of the fluid stream above and below the point of entry of the substance to be monitored, and measuring and comparing the resulting change in temperature of the sections. Advantage is taken of the difference in thermal characteristics of the fluid and the substance to be measured to correlate temperature differences in the sections above and below the substance feed point for providing an indication of the mass flow rate of the substance.

  19. Efficient generation in a chemical oxygen - iodine laser with a low buffer-gas flow rate

    SciTech Connect

    Azyazov, V N; Safonov, V S; Ufimtsev, N I

    2002-09-30

    The efficient generation in a chemical oxygen - iodine laser (COIL) with a low buffer-gas flow rate for Mach numbers M {<=} 1 is demonstrated. The maximum output power of the COIL was 415 W for a molecular chlorine flow rate of 20 mmol s{sup -1}, which corresponds to a chemical efficiency {eta}{sub ch} =23%. It is shown that the substitution of the buffer gas CO{sub 2} for N{sub 2} does not cause any significant variation in the dependence of the output power on the degree of dilution of the active medium. (lasers)

  20. The Effects of Bottom Blowing Gas Flow Rate Distribution During the Steelmaking Converter Process on Mixing Efficiency

    NASA Astrophysics Data System (ADS)

    Chu, Kuan-Yu; Chen, Hsing-Hao; Lai, Po-Han; Wu, Hsuan-Chung; Liu, Yung-Chang; Lin, Chi-Cheng; Lu, Muh-Jung

    2016-04-01

    Featuring the advantages of top-blown and bottom-blown oxygen converters, top and bottom combined blown converters are mainstream devices used in steelmaking converter. This study adopted the FLUENT software to develop a numerical model that simulates 3D multiphase flows of gas (air and argon), liquid steel, and slag. Ten numerical experiments were conducted to analyze the effects that the bottom blowing gas flow rate distribution patterns (uniform, linear fixed total flow rate, linear fixed maximal flow rate, and V-type) and bottom blowing gas flow distribution gradients of combined blown converters exert on slag surface stirring heights, flow field patterns, simulation system dynamic pressures, mixing time, and liquid steel-slag interface velocity. The simulation results indicated that the mixing efficiency was highest for the linear fixed total flow rate, followed by the linear fixed maximal flow rate, V-type, and uniform patterns. The bottom blowing gas flow rate distribution exhibited linear patterns and large gradients, and high bottom blowing total flow rates increased the mixing efficiency substantially. In addition, the results suggested that even when bottom blowing total flow rate was reduced, adopting effective bottom blowing gas flow rate distribution patterns and gradients could improve the mixing efficiency.

  1. Using stream sediment lithology to explore the roles of abrasion and channel network structure in shaping downstream sediment yields

    NASA Astrophysics Data System (ADS)

    Mueller, E. R.; Smith, M. E.; Pitlick, J.

    2012-12-01

    Both the flux and characteristics of stream sediment evolve downstream in response to variations in sediment supply, abrasion rate, and channel network structure. We use a simple erosion-abrasion mass balance to model the downstream evolution of sediment flux in two adjacent watersheds draining differing mixtures of soft and resistant rock types in the northern Rocky Mountains. Measurements of bed sediment grain size and lithology are used in conjunction with measured bed load and suspended load sediment fluxes to constrain the model. The results show that the downstream evolution in bed load flux and composition can be strongly influenced by subtle differences in underlying geology, which shapes both the abrasion characteristics and travel path lengths of individual rock types. In the Big Wood basin, abrasion rapidly reduces the size of soft sedimentary and volcanic rocks exposed in headwater areas, concentrating resistant granitic rocks in the stream bed and depressing bed load in favor of suspended load. Alternatively, in the North Fork Big Lost basin, volcanic and sedimentary lithologies are exposed throughout the catchment, and the bed material becomes dominated by erodible but resistant quartzitic sandstones. The result is a much higher bed load flux best modeled with modest abrasion rates. In both cases, the best-fit model can reproduce within 5% the composition of the stream bed substrate using realistic erosion and abrasion parameters. The results also demonstrate a strong linkage between modern hillslopes and channel systems even in these formerly glaciated landscapes, as the sediment signature of the primary streams reflects the systematic tapping of distinct source areas. While this work shows promise, measurement of the spatial patterns in the size and composition of bed and suspended load fluxes at locations throughout a channel network would better elucidate that relative importance of supply, sorting, and abrasion processes.

  2. Reaction and internal energy relaxation rates in viscous thermochemically non-equilibrium gas flows

    SciTech Connect

    Kustova, E. V.; Oblapenko, G. P.

    2015-01-15

    In the present paper, reaction and energy relaxation rates as well as the normal stress are studied for viscous gas flows with vibrational and chemical non-equilibrium. Using the modified Chapman-Enskog method, multi-temperature models based on the Treanor and Boltzmann vibrational distributions are developed for the general case taking into account all kinds of vibrational energy transitions, exchange reactions, dissociation, and recombination. Integral equations specifying the first-order corrections to the normal mean stress and reaction rates are derived, as well as approximate systems of linear equations for their numerical computation. Generalized thermodynamic driving forces associated with all non-equilibrium processes are introduced. It is shown that normal stresses and rates of non-equilibrium processes can be expressed in terms of the same driving forces; the symmetry of kinetic coefficients in these expressions is proven. The developed general model is applied to a particular case of a pure N{sub 2} viscous flow with slow VT relaxation. Normal stress and rates of vibrational relaxation are studied for various ratios of vibrational and translational temperatures. The cross effects between different vibrational transitions in viscous flows are evaluated, along with the influence of anharmonicity and flow compressibility on the first-order corrections to the relaxation rate. Limits of validity for the widely used Landau–Teller model of vibrational relaxation are indicated.

  3. A non-contact optical procedure for precise measurement of respiration rate and flow

    NASA Astrophysics Data System (ADS)

    Scalise, Lorenzo; Marchionni, Paolo; Ercoli, Ilaria

    2010-04-01

    The use of standard instrumentation for the assessment of the respiration rate as of flow is an important goal in medicine. Spirometers, textile-based capacitive sensors or photopletismography are standard contact instrumentations used for such aim; the main drawback in the use of such instrumentations is the necessity to have a direct contact of the instrument with the patient. In this paper, we present an optical no-contact method for monitoring of both the respiration rate and flow. This method is based on the measurement of external chest wall movement by a laser Doppler vibrometer. The measurement procedure has already been demonstrated to be extremely well performing for what concern the monitoring of the cardiac activity. The proposed method can be operated at a distance of 1.5 m, on different point of the patient thoracic and abdominal area. We have monitored respiration rate and flow on 8 patients with a spirometer and simultaneously with the proposed noncontact measurement procedure. Bland-Altman analysis of the respiration rate measured with both instruments demonstrate a mean error on the determination of the respiration rate of < 1% and of the < 4% for the instantaneous flow. We also report a study on the optimal position on the thoracic area based on quality of the signal measured on the same population of subject.

  4. Soybean seedlings tolerate abrasion from air-propelled grit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New tools for controlling weeds would be useful for soybean production in organic systems. Air-propelled abrasive grit is one such tool that performs well for in-row weed control in corn, but crop safety in soybean is unknown. We examined responses to abrasion by corn-cob grit of soybean seedlings a...

  5. Sand abrasion injury and biomass partitiioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind blown soil particle abrasion negatively impacts millions of hectares of crops annually. The goal of this study was to examine the effects of wind and wind blown sand abrasion damage on cotton (Gossypium hirsutum L.) seedling biomass partitioning to leaves, stems, and roots. Seedlings of three ...

  6. 29 CFR 1926.303 - Abrasive wheels and tools.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 8 2014-07-01 2014-07-01 false Abrasive wheels and tools. 1926.303 Section 1926.303 Labor... (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Tools-Hand and Power § 1926.303 Abrasive wheels and tools. (a) Power. All grinding machines shall be supplied with sufficient power to maintain...

  7. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Abrasive device and accessories. 872.6010 Section 872.6010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and...

  8. 21 CFR 872.6010 - Abrasive device and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Abrasive device and accessories. 872.6010 Section 872.6010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and...

  9. Abrasion of 6 dentifrices measured by vertical scanning interference microscopy

    PubMed Central

    PASCARETTI-GRIZON, Florence; MABILLEAU, Guillaume; CHAPPARD, Daniel

    2013-01-01

    Objectives The abrasion of dentifrices is well recognized to eliminate the dental plaque. The aims of this study were to characterize the abrasive powders of 6 dentifrices (3 toothpastes and 3 toothpowders) and to measure the abrasion on a test surface by Vertical Scanning Interference microscopy (VSI). Material and Methods Bright field and polarization microscopy were used to identify the abrasive particles on the crude dentifrices and after prolonged washes. Scanning electron microscopy and microanalysis characterized the shape and nature of the particles. Standardized and polished blocks of poly(methylmethacrylate) were brushed with a commercial electric toothbrush with the dentifrices. VSI quantified the mean roughness (Ra) and illustrated in 3D the abraded areas. Results Toothpastes induced a limited abrasion. Toothpowders induced a significantly higher roughness linked to the size of the abrasive particles. One powder (Gencix® produced a high abrasion when used with a standard testing weight. However, the powder is based on pumice particles covered by a plant homogenate that readily dissolves in water. When used in the same volume, or after dispersion in water, Ra was markedly reduced. Conclusion Light and electron microscopy characterize the abrasive particles and VSI is a new tool allowing the analysis of large surface of abraded materials. PMID:24212995

  10. Sand abrasion injury and biomass partitioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind blown soil particle abrasion negatively impacts millions of hectares of crops annually. The goal of this study was to examine the effects of wind and wind blown sand abrasion damage on cotton (Gossypium hirsutum L.) seedling biomass partitioning to leaves, stems, and roots. Seedlings of three ...

  11. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... of the American National Standard Safety Code for the Use, Care, and Protection of Abrasive Wheels... Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery....

  12. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... of the American National Standard Safety Code for the Use, Care, and Protection of Abrasive Wheels... Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery....

  13. Cotton seedling abrasion and recovery from wind blown sand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of hectares of crops are exposed to wind blown sand abrasion each year and in many instances the damage is thought to be severe enough to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton (Gossypium hirsutum L.) seedlings...

  14. 29 CFR 1910.215 - Abrasive wheel machinery.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 5 2010-07-01 2010-07-01 false Abrasive wheel machinery. 1910.215 Section 1910.215 Labor... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery. (a... wheel in motion. (5) Excluded machinery. Natural sandstone wheels and metal, wooden, cloth, or...

  15. Sand abrasion injury and biomass partitioning in cotton seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Millions of acres of crops are exposed to wind blown sand abrasion injury each year and in many instances the damage is thought to be sufficiently severe to require replanting. The goal of this study was to determine the effects of wind blown sand abrasion duration on cotton seedlings. Seedlings of ...

  16. Peak flow rate and recession-curve characteristics of a karst spring in the Inner Bluegrass, central Kentucky

    USGS Publications Warehouse

    Felton, G.K.; Currens, J.C.

    1994-01-01

    The flow rate at the terminal spring of a 1929 ha karst ground-water catchment has been continuously monitored for 2 years, and 108 identifiable events were analyzed. The peak flow rates followed a beta frequency distribution with parameters ?? = 0.365 and ?? = 1.135. Events were separated into high-flow and low-flow. High-flow events had characteristics attributable to pipe flow. Correlation and stepwise regression were used to develop peak flow rate prediction equations for the combined 108 events and for the 81 low-flow events. The portion of the recession curve identified as pipe flow was a watershed constant and time invariant. The base flow was seasonal, increasing in the winter to approximately 0.071 m3s-1 and decreasing in the summer to approximately 0.014 m3s-1. ?? 1994.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  18. Electron-impact vibrational excitation rates in the flow field of aeroassisted orbital transfer vehicles

    NASA Technical Reports Server (NTRS)

    Lee, J.-H.

    1985-01-01

    This paper examines the vibrational excitation rate processes expected in the flow field of aeroassisted orbital transfer vehicles (AOTVs). An analysis of the multiple-quantum vibrational excitation processes by electron impact is made to predict the vibrational excitation cross sections, rate coefficients, and relaxation times which control vibrational temperature. The expression for the rate of electron-vibration energy transfer is derived by solving the system of master equations which account for the multiple-level transitions. The vibrational excitation coefficients, which are the prerequisite physical quantities in solving the obtained vibrational equation, are calculated based on the theoretically predicted cross sections. These cross sections are obtained from quantum mechanical calculations, based on the concept that vibrational excitation of molecules by electron impact occurs through formation of an intermediate negative ion state. Finally, the modified Landau-Teller-type rate equation, which is suitable for the numerical calculations for the AOTV flow fields, is suggested.

  19. Development of a mechanistic model for predicting corrosion rate in multiphase oil/water/gas flows

    SciTech Connect

    Zhang, R.; Gopal, M.; Jepson, W.P.

    1997-09-01

    A mechanistic model has been developed to predict corrosion rates in multiphase (water/oil/CO{sub 2}) flow conditions. The model takes into account electrochemistry, reaction kinetics, and, mass transport effects. This paper describes the equations used to determine pH and bulk concentrations of various ions, which are then used to calculate the mass transfer rates to the corrosion surface. The result includes the determination of the mass transfer coefficients of various ionic species and corrosion rates. Details of relations used for determination of mass transfer coefficients for multiphase flows, and rates of electrochemical reaction kinetics are discussed and predicted results are compared with experimental observations. Agreement between model results and experimental data is good.

  20. Expanding the range for predicting critical flow rates of gas wells producing from normally pressured waterdrive reservoirs

    SciTech Connect

    Upchurch, E.R. )

    1989-08-01

    The critical flow rate of a gas well is the minimum flow rate required to prevent accumulation of liquids in the tubing. Theoretical models currently available for estimating critical flow rates are restricted to wells with water/gas ratios less than 150bbl/MMcf (0.84 X 10/sup -3/ m/sup 3//m/sup 3/). For wells producing at higher water/gas ratios from normally pressured waterdrive reservoirs, a method of estimating critical flow rates is derived through use of an empirical multiphase-flow correlation.

  1. Zero-valent iron removal rates of aqueous Cr(VI) measured under flow conditions

    SciTech Connect

    Kaplan, Daniel I.; Gilmore, Tyler J.

    2004-06-30

    The rates of Cr(VI) removal from the aqueous phase by zero-valent iron Fe(0) was measured under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a gournwater remediation technology that replaces the sand in a filter pack of a conventioanl well with a reactive material, such as Fe(0).

  2. Evaluation of planarization performance for a novel alkaline copper slurry under a low abrasive concentration

    NASA Astrophysics Data System (ADS)

    Mengting, Jiang; Yuling, Liu; Haobo, Yuan; Guodong, Chen; Weijuan, Liu

    2014-11-01

    A novel alkaline copper slurry that possesses a relatively high planarization performance is investigated under a low abrasive concentration. Based on the action mechanism of CMP, the feasibility of using one type of slurry in copper bulk elimination process and residual copper elimination process, with different process parameters, was analyzed. In addition, we investigated the regular change of abrasive concentration effect on copper and tantalum removal rate and within wafer non-uniformity (WIWNU) in CMP process. When the abrasive concentration is 3 wt%, in bulk elimination process, the copper removal rate achieves 6125 Å/min, while WIWNU is 3.5%, simultaneously. In residual copper elimination process, the copper removal rate is approximately 2700 Å/min, while WIWNU is 2.8%. Nevertheless, the tantalum removal rate is 0 Å/min, which indicates that barrier layer isn't eliminated in residual copper elimination process. The planarization experimental results show that an excellent planarization performance is obtained with a relatively high copper removal rate in bulk elimination process. Meanwhile, after residual copper elimination process, the dishing value increased inconspicuously, in a controllable range, and the wafer surface roughness is only 0.326 nm (sq < 1 nm) after polishing. By comparison, the planarization performance and surface quality of alkaline slurry show almost no major differences with two kinds of commercial acid slurries after polishing. All experimental results are conducive to research and improvement of alkaline slurry in the future.

  3. Microfracture patterns of abrasive wear striations on teeth indicate directionality.

    PubMed

    Gordon, K R

    1984-03-01

    A method is described that will indicate the direction that an abrasive particle was traveling as it scored the surface of a brittle material. Light and scanning electron micrographs of glass, dentine, and enamel abraded by loose and, steel carbide, and diamond indicate that partial Hertzian fracture cones are formed at the margins of wear striations during abrasion. The bases of these fracture cones face in the direction of travel of the abrasive particle and, therefore, indicate directionality. Because this method is based only on the consistent geometry of fracturing of brittle materials, it is independent of the loading of the abrasive particle. The only other method available to determine directionality of striations is unreliable since it uses the width of striations, and, hence, is dependent upon a consistent loading regime of the abrasive particle. This new method has direct application for determining the direction of movement of the jaws during mastication in living or fossil animals. PMID:6731603

  4. Solidification Structure and Abrasion Resistance of High Chromium White Irons

    SciTech Connect

    Dogan, O.N.; Hawk, J.A.; Laird, George, II

    1997-06-01

    Superior abrasive wear resistance, combined with relatively low production costs, makes high Cr white cast irons (WCIs) particularly attractive for applications in the grinding, milling, and pumping apparatus used to process hard materials. Hypoeutectic, eutectic, and hypereutectic cast iron compositions, containing either 15 or 26 wt pct chromium, were studied with respect to the macrostructural transitions of the castings, solidification paths, and resulting microstructures when poured with varying superheats. Completely equiaxed macrostructures were produced in thick section castings with slightly hypereutectic compositions. High-stress abrasive wear tests were then performed on the various alloys to examine the influence of both macrostructure and microstructure on wear resistance. Results indicated that the alloys with a primarily austenitic matrix had a higher abrasion resistance than similar alloys with a pearlitic/bainitic matrix. Improvement in abrasion resistance was partially attributed to the ability of the austenite to transform to martensite at the wear surface during the abrasion process.

  5. Solidification structure and abrasion resistance of high chromium white irons

    SciTech Connect

    Dogan, O.N.; Hawk, J.A.; Laird, G. II

    1997-06-01

    Superior abrasive wear resistance, combined with relatively low production costs, makes high Cr white cast irons (WCIs) particularly attractive for applications in the grinding, milling, and pumping apparatus used to process hard materials. Hypoeutectic, eutectic, and hypereutectic cast iron compositions, containing either 15 or 26 wt pct chromium, were studied with respect to the macrostructural transitions of the castings, solidification paths, and resulting microstructures when poured with varying superheats. Completely equiaxed macrostructures were produced in thick section castings with slightly hypereutectic compositions. High-stress abrasive wear tests were then performed on the various alloys to examine the influence of both macrostructure and microstructure on wear resistance. Results indicated that the alloys with a primarily austenitic matrix had a higher abrasion resistance than similar alloys with a pearlitic/bainitic matrix. Improvement in abrasion resistance was partially attributed to the ability of the austenite to transform to martensite at the wear surface during the abrasion process.

  6. Effects of Gas Flow Rate on the Discharge Characteristics of a DC Excited Plasma Jet

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Jia, Pengying; Di, Cong; Bao, Wenting; Zhang, Chunyan

    2015-09-01

    A direct current (DC) source excited plasma jet consisting of a hollow needle anode and a plate cathode has been developed to form a diffuse discharge plume in ambient air with flowing argon as the working gas. Using optical and electrical methods, the discharge characteristics are investigated for the diffuse plasma plume. Results indicate that the discharge has a pulse characteristic, under the excitation of a DC voltage. The discharge pulse corresponds to the propagation process of a plasma bullet travelling from the anode to the cathode. It is found that, with an increment of the gas flow rate, both the discharge plume length and the current peak value of the pulsed discharge decrease in the laminar flow mode, reach their minima at about 1.5 L/min, and then slightly increase in the turbulent mode. However, the frequency of the pulsed discharge increases in the laminar mode with increasing the argon flow rate until the argon flow rate equals to about 1.5 L/min, and then slightly decreases in the turbulent mode. supported by National Natural Science Foundation of China (Nos. 10805013, 11375051), Funds for Distinguished Young Scientists of Hebei Province, China (No. A2012201045), Department of Education for Outstanding Youth Project of China (No. Y2011120), and Youth Project of Hebei University of China (No. 2011Q14)

  7. Research on Gas-liquid Flow Rate Optimization in Foam Drilling

    NASA Astrophysics Data System (ADS)

    Gao, B. K.; Sun, D. G.; Jia, Z. G.; Huang, Z. Q.

    2010-03-01

    With the advantages of less gas consumption, higher carrying rocks ability, lower leakage and higher penetration rate, foam drilling is widely used today in petroleum industry. In the process of foam underbalanced drilling, the mixture of gas, liquid and cuttings flows upwards through the annular, so it is a typical gas-liquid-solid multi-phase flow. In order to protect the reservoir and avoid borehole wall collapsing during foam drilling, it is crucial to ensure that the bottom hole pressure is lower than the formation pressure and higher than the formation collapse pressure, and in the mean time, foam drilling fluid in the whole wellbore should be in the best foam quality stage in order to have sufficient capacity to carry cuttings. In this paper, main relations between bottom hole pressure and gas-liquid injecting rate are analyzed with the underbalanced multiphase flow models. And in order to obtain precise flow pattern and flow pressure, the whole well bore is spatial meshed and iterative method is used. So, a convenient safety window expressed by gas-liquid injecting rate is obtained instead of that by bottom hole pressure. Finally, a foam drilling example from a block in Yemen is presented; the drilling results show that this method is reliable and practical.

  8. Design and experimental study of high-speed low-flow-rate centrifugal compressors

    SciTech Connect

    Gui, F.; Reinarts, T.R.; Scaringe, R.P.; Gottschlich, J.M.

    1995-12-31

    This paper describes a design and experimental effort to develop small centrifugal compressors for aircraft air cycle cooling systems and small vapor compression refrigeration systems (20--100 tons). Efficiency improvements at 25% are desired over current designs. Although centrifugal compressors possess excellent performance at high flow rates, low-flow-rate compressors do not have acceptable performance when designed using current approaches. The new compressors must be designed to operate at a high rotating speed to retain efficiency. The emergence of the magnetic bearing provides the possibility of developing such compressors that run at speeds several times higher than current dominating speeds. Several low-flow-rate centrifugal compressors, featured with three-dimensional blades, have been designed, manufactured and tested in this study. An experimental investigation of compressor flow characteristics and efficiency has been conducted to explore a theory for mini-centrifugal compressors. The effects of the overall impeller configuration, number of blades, and the rotational speed on compressor flow curve and efficiency have been studied. Efficiencies as high as 84% were obtained. The experimental results indicate that the current theory can still be used as a guide, but further development for the design of mini-centrifugal compressors is required.

  9. Cerberus Fossae and Elysium Planitia Lavas, Mars: Source Vents, Flow Rates, Edifice Styles and Water Interactions

    NASA Technical Reports Server (NTRS)

    Sakimoto, S. E. H.; Gregg, T. K. P.

    2004-01-01

    The Cerberus Fossae and Elysium Planitia regions have been suggested as some of the youngest martian surfaces since the Viking mission, although there was doubt whether the origins were predominantly volcanic or fluvial. The Mars Global Surveyor and Mars Odyssey Missions have shown that the region is certainly young in terms of the topographic preservation and the youthful crater counts (e.g. in the tens to a few hundred million yrs.). Numerous authors have shown that fluvial and volcanic features share common flow paths and vent systems, and that there is evidence for some interaction between the lava flows and underlying volatiles as well as the use by lavas and water of the same vent system. Given the youthful age and possible water-volcanism interaction environment, we'd like constraints on water and volcanic flux rates and interactions. Here, we model ranges of volcanic flow rates where we can well-constrain them, and consider the modest flow rate results results in context with local eruption styles, and track vent locations, edifice volumes, and flow sources and data.

  10. Evaluation of reaction rates in streambed sediments with seepage flow: a novel code

    NASA Astrophysics Data System (ADS)

    Boano, Fulvio; De Falco, Natalie; Arnon, Shai

    2015-04-01

    Streambed interfaces represent hotspots for nutrient transformations because they host different microbial species which perform many heterotrophic and autotrophic reactions. The evaluation of these reaction rates is crucial to assess the fate of nutrients in riverine environments, and it is often performed through the analysis of concentrations from water samples collected along vertical profiles. The most commonly employed evaluation tool is the Profile code developed by Berg et al. (1998), which determines reaction rates by fitting observed concentrations to a diffusion-reaction equation that neglects the presence of water flow within sediments. However, hyporheic flow is extremely common in streambeds, where solute transport is often controlled by advection rather than diffusion. There is hence a pressing need to develop new methods that can be applied even to advection-dominated sediments. This contribution fills this gap by presenting a novel approach that extends the method proposed by Berg et al. (1998). This new approach includes the influence of vertical solute transport by upwelling or downwelling water, and it is this suited to the typical flow conditions of stream sediments. The code is applied to vertical profiles of dissolved oxygen from a laboratory flume designed to mimic the complex flow conditions of real streams. The results show that it is fundamental to consider water flow to obtain reliable estimates of reaction rates in streambeds. Berg, P., N. Risgaard-Petersen, and S. Rysgaard, 1998, Interpretation of measured concentration profiles in the sediment porewater, Limnology and Oceanography, 43:1500-1510.

  11. Review of flow rate estimates of the Deepwater Horizon oil spill

    PubMed Central

    McNutt, Marcia K.; Camilli, Rich; Crone, Timothy J.; Guthrie, George D.; Hsieh, Paul A.; Ryerson, Thomas B.; Savas, Omer; Shaffer, Frank

    2012-01-01

    The unprecedented nature of the Deepwater Horizon oil spill required the application of research methods to estimate the rate at which oil was escaping from the well in the deep sea, its disposition after it entered the ocean, and total reservoir depletion. Here, we review what advances were made in scientific understanding of quantification of flow rates during deep sea oil well blowouts. We assess the degree to which a consensus was reached on the flow rate of the well by comparing in situ observations of the leaking well with a time-dependent flow rate model derived from pressure readings taken after the Macondo well was shut in for the well integrity test. Model simulations also proved valuable for predicting the effect of partial deployment of the blowout preventer rams on flow rate. Taken together, the scientific analyses support flow rates in the range of ∼50,000–70,000 barrels/d, perhaps modestly decreasing over the duration of the oil spill, for a total release of ∼5.0 million barrels of oil, not accounting for BP's collection effort. By quantifying the amount of oil at different locations (wellhead, ocean surface, and atmosphere), we conclude that just over 2 million barrels of oil (after accounting for containment) and all of the released methane remained in the deep sea. By better understanding the fate of the hydrocarbons, the total discharge can be partitioned into separate components that pose threats to deep sea vs. coastal ecosystems, allowing responders in future events to scale their actions accordingly. PMID:22187459

  12. Review of flow rate estimates of the Deepwater Horizon oil spill

    USGS Publications Warehouse

    McNutt, Marcia K.; Camilli, Rich; Crone, Timothy J.; Guthrie, George D.; Hsieh, Paul A.; Ryerson, Thomas B.; Savas, Omer; Shaffer, Frank

    2012-01-01

    The unprecedented nature of the Deepwater Horizon oil spill required the application of research methods to estimate the rate at which oil was escaping from the well in the deep sea, its disposition after it entered the ocean, and total reservoir depletion. Here, we review what advances were made in scientific understanding of quantification of flow rates during deep sea oil well blowouts. We assess the degree to which a consensus was reached on the flow rate of the well by comparing in situ observations of the leaking well with a time-dependent flow rate model derived from pressure readings taken after the Macondo well was shut in for the well integrity test. Model simulations also proved valuable for predicting the effect of partial deployment of the blowout preventer rams on flow rate. Taken together, the scientific analyses support flow rates in the range of ~50,000–70,000 barrels/d, perhaps modestly decreasing over the duration of the oil spill, for a total release of ~5.0 million barrels of oil, not accounting for BP's collection effort. By quantifying the amount of oil at different locations (wellhead, ocean surface, and atmosphere), we conclude that just over 2 million barrels of oil (after accounting for containment) and all of the released methane remained in the deep sea. By better understanding the fate of the hydrocarbons, the total discharge can be partitioned into separate components that pose threats to deep sea vs. coastal ecosystems, allowing responders in future events to scale their actions accordingly.

  13. Variability in venom volume, flow rate and duration in defensive stings of five scorpion species.

    PubMed

    van der Meijden, Arie; Coelho, Pedro; Rasko, Mykola

    2015-06-15

    Scorpions have been shown to control their venom usage in defensive encounters, depending on the perceived threat. Potentially, the venom amount that is injected could be controlled by reducing the flow speed, the flow duration, or both. We here investigated these variables by allowing scorpions to sting into an oil-filled chamber, and recording the accreting venom droplets with high-speed video. The size of the spherical droplets on the video can then be used to calculate their volume. We recorded defensive stings of 20 specimens representing 5 species. Significant differences in the flow rate and total expelled volume were found between species. These differences are likely due to differences in overall size between the species. Large variation in both venom flow speed and duration are described between stinging events of single individuals. Both venom flow rate and flow duration correlate highly with the total expelled volume, indicating that scorpions may control both variables in order to achieve a desired end volume of venom during a sting. PMID:25911958

  14. A methodology to reduce uncertainties in the high-flow portion of the rating curve for Goodwater Creek Watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flow monitoring at watershed scale relies on the establishment of a rating curve that describes the relationship between stage and flow and is developed from actual flow measurements at various stages. Measurement errors increase with out-of-bank flow conditions because of safety concerns and diffic...

  15. Energy policy act transportation study: Interim report on natural gas flows and rates

    SciTech Connect

    1995-11-17

    This report, Energy Policy Act Transportation Study: Interim Report on Natural Gas Flows and Rates, is the second in a series mandated by Title XIII, Section 1340, ``Establishment of Data Base and Study of Transportation Rates,`` of the Energy Policy Act of 1992 (P.L. 102--486). The first report Energy Policy Act Transportation Study: Availability of Data and Studies, was submitted to Congress in October 1993; it summarized data and studies that could be used to address the impact of legislative and regulatory actions on natural gas transportation rates and flow patterns. The current report presents an interim analysis of natural gas transportation rates and distribution patterns for the period from 1988 through 1994. A third and final report addressing the transportation rates and flows through 1997 is due to Congress in October 2000. This analysis relies on currently available data; no new data collection effort was undertaken. The need for the collection of additional data on transportation rates will be further addressed after this report, in consultation with the Congress, industry representatives, and in other public forums.

  16. An experimental and theoretical study of the flow phenomena within a vortex sink rate sensor

    NASA Technical Reports Server (NTRS)

    Goglia, G. L.; Patel, D. K.

    1974-01-01

    Tests were conducted to obtain a description of the flow field within a vortex sink rate sensor and to observe the influence of viscous effects on its performance. The characteristics of the sensor are described. The method for conducting the test is reported. It was determined that for a specific mass flow rate and the geometry of the vortex chamber, the flow in the vortex chamber was only affected, locally, by the size of the sink tube diameter. Within the sink tube, all three velocity components were found to be higher for the small sink tube diameters. As the speed of rotation of the sensor was increased, the tangential velocities within the vortex chamber, as well as in the sink tube, increased in proportion to the speed of rotation.

  17. Flow rate estimation by optical coherence tomography using contrast dilution approach

    NASA Astrophysics Data System (ADS)

    Štohanzlová, Petra; Kolář, Radim

    2015-07-01

    This paper describes experiments and methodology for flow rate estimation using optical coherence tomography and dilution method in single fiber setup. The single fiber is created from custom made glass capillary and polypropylene hollow fiber. As a data source, measurements on single fiber phantom with continuous flow of carrier medium and bolus of Intralipid solution as a contrast agent were used using Thorlabs OCT OCS1300SS. The measured data were processed by methods of image processing, in order to precisely align the individual images in the sequence and extract dilution curves from the area inside the fiber. An experiment proved that optical coherence tomography can be used for flow rate estimation by the dilution method with precision around 7%.

  18. Velocity and flow rate measurement of liquid metal by contactless electromagnetic Lorentz force technique

    NASA Astrophysics Data System (ADS)

    Dubovikova, N.; Karcher, C.; Kolesnikov, Y.

    2016-07-01

    Providing flow analysis in case of aggressive and hot liquids is a complicated task, especially when liquid's composition and, hence, its physical properties, are unknown. Contactless techniques are the most promising methods for liquid metal flow rate control and some of these methods are based on electromagnetic induction of breaking force acting on an electrically conductive fluid which is moving through a magnetic field. One of the techniques is time-of-flight Lorentz force velocimetry (LFV). By using the method one can estimate volumetric flow rate without knowing of electrical conductivity, magnitude of magnetic field or characteristic dimension. The most important and crucial challenge within the technique is detection of small fluctuations of Lorentz force value. In this article we will focus on application and investigation of time-of-flight LFV.

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

    NASA Astrophysics Data System (ADS)

    Prasetyaningrum, A.; Ratnawati, Jos, B.

    2015-12-01

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O3) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

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

    PubMed

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

    2000-11-01

    There are significant differences of glucose retention in site-specificity and individuals. Sixty-two 5-year-old nursery schoolchildren participated in this study on the relation between the viscosity of saliva and flow rate and glucose retention. Each child was instructed to rinse his/her mouth with a glucose solution (0.5 M, 5 ml) and then to spit out. Three minutes after rinsing, glucose retention was determined. Resting saliva was collected by a natural outflow method, then the flow rate was determined. A rotational viscometer was used to determine the viscosity. Glucose retention and flow rate were correlated at the left maxillary primary molars, and glucose retention and viscosity were correlated at the maxillary central primary incisors. It was concluded that glucose retention after glucose mouth rinsing was site-specific, and that glucose retention and the index of decayed, missing and filled primary teeth (dmft) were slightly correlated with the salivary viscosity and flow rate. PMID:11000387

  1. Effects of concentration and sniff flow rate on the rat electroolfactogram.

    PubMed

    Scott, John W; Acevedo, Humberto P; Sherrill, Lisa

    2006-07-01

    Previous reports using the electroolfactogram (EOG) to study the spatial and temporal aspects of response in the rodent olfactory epithelium had focused on high odorant concentrations that gave large responses. This investigation has used lower concentrations to test the difference between responses in the rat dorsomedial and lateral recesses with a range of nasal flow rates and a range of chemical properties. The responses to a highly polar, more hydrophilic odorant changed more steeply with flow rate than responses to a very nonpolar, hydrophobic odorant. With low flow rates there was a response delay in the lateral recess, which is consistent with the models indicating lower flow rates in that region. We observed significant volume conduction effects in which large responses in the dorsomedial region obscured smaller initial portions of the lateral responses. These effects could be removed by destroying the dorsomedial response with a high concentration of a low molecular weight ester. We caution that investigators of EOG recordings from the intact epithelium must attend to the possible presence of volume conduction, which can be assessed by attention to the selectivity of odorant response, response waveform, and response latency. PMID:16740644

  2. Effects of Concentration and Sniff Flow Rate on the Rat Electroolfactogram

    PubMed Central

    Scott, John W.; Acevedo, Humberto P.; Sherrill, Lisa

    2008-01-01

    Previous reports using the electroolfactogram (EOG) to study the spatial and temporal aspects of response in the rodent olfactory epithelium had focused on high odorant concentrations that gave large responses. This investigation has used lower concentrations to test the difference between responses in the rat dorsomedial and lateral recesses with a range of nasal flow rates and a range of chemical properties. The responses to a highly polar, more hydrophilic odorant changed more steeply with flow rate than responses to a very non-polar, hydrophobic odorant. With low flow rates there was a response delay in the lateral recess, which is consistent with the models indicating lower flow rates in that region. We observed significant volume conduction effects in which large responses in the dorsomedial region obscured smaller initial portions of the lateral responses. These effects could be removed by destroying the dorsomedial response with a high concentration of a low molecular weight ester. We caution that investigators of EOG recordings from the intact epithelium must attend to the possible presence of volume conduction, which can be assessed by attention to the selectivity of odorant response, response waveform, and response latency. PMID:16740644

  3. URBAN WET-WEATHER FLOW MICROBIAL CONTAMINATION: HIGH-RATE TREATMENT APPROACHES

    EPA Science Inventory

    fThis presentation is on high-rate disinfection of wet-weather flow (WWF) and pretreatment processes of suspended solids to enhance the disinfection. A discussion of pretreatment processes and of the newest disinfection technologies used for WWF is included, along with the feasib...

  4. NORMAL OF RANGE OF DIURNAL CHANGES IN PEAK EXPIRATORY FLOW RATES

    EPA Science Inventory

    Measuring peak expiratory flow rates (PEFR) several times a day can provide an objective assessment of functional changes relative to environmental or occupational exposures. his report describes the pattern of diurnal changes in PEFR in a reference population, and defines ranges...

  5. Flow, aeration, and carbon dioxide transfer rates for airlifts used in recirculating aquaculture systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Airlift pumping systems reduce the electrical costs of moving water in a recirculating aquaculture system and can be concurrently designed to aerate water and remove carbon dioxide. This study determined the water flow, oxygen transfer, and CO2 removal rates for water using airlift technology in a 1...

  6. Forecasting Student Entrants, Flows and Success Rates. Technical Report. Studies in Institutional Management in Higher Education.

    ERIC Educational Resources Information Center

    Han, Stjepan; And Others

    This document is concerned with an information system to study the internal dynamics of student flows, choice of subjects and success rates, taking into account different regional affiliations and the socioeconomic backgrounds of students. Among the external factors to be considered will be the demographic dimension in terms of changes in the…

  7. ESTIMATION OF PHYTOPLANKTON DECOMPOSITION RATES USING TWO-STAGE CONTINUOUS FLOW STUDIES

    EPA Science Inventory

    A two-stage continuous flow (TSCF) system was used to quantify phytoplankton decomposition rates and to characterize the decay process as a function of phytoplankton species, phytoplankton physiological state, and the presence and character of a decomposer community. A TSCF syste...

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

    SciTech Connect

    Prasetyaningrum, A. Ratnawati,; Jos, B.

    2015-12-29

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

  9. 40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642...

  10. 40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642...

  11. 40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642...

  12. 40 CFR 1065.642 - SSV, CFV, and PDP molar flow rate calculations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false SSV, CFV, and PDP molar flow rate calculations. 1065.642 Section 1065.642 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.642...

  13. Effect of reference conditions on flow rate, modifier fraction and retention in supercritical fluid chromatography.

    PubMed

    De Pauw, Ruben; Shoykhet Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

    2016-08-12

    When using compressible mobile phases such as fluidic CO2, the density, the volumetric flow rates and volumetric fractions are pressure dependent. The pressure and temperature definition of these volumetric parameters (referred to as the reference conditions) may alter between systems, manufacturers and operating conditions. A supercritical fluid chromatography system was modified to operate in two modes with different definition of the eluent delivery parameters, referred to as fixed and variable mode. For the variable mode, the volumetric parameters are defined with reference to the pump operating pressure and actual pump head temperature. These conditions may vary when, e.g. changing the column length, permeability, flow rate, etc. and are thus variable reference conditions. For the fixed mode, the reference conditions were set at 150bar and 30°C, resulting in a mass flow rate and mass fraction of modifier definition which is independent of the operation conditions. For the variable mode, the mass flow rate of carbon dioxide increases with system pump operating pressure, decreasing the fraction of modifier. Comparing the void times and retention factor shows that the deviation between the two modes is almost independent of modifier percentage, but depends on the operating pressure. Recalculating the set volumetric fraction of modifier to the mass fraction results in the same retention behaviour for both modes. This shows that retention in SFC can be best modelled using the mass fraction of modifier. The fixed mode also simplifies method scaling as it only requires matching average column pressure. PMID:27401813

  14. Experimental Determination of The Space and Flow Rate Dependency of The Subsoil Transport Parameters

    NASA Astrophysics Data System (ADS)

    Javaux, M.; Vanclooster, M.

    Within this presentation, the influence of the flow rate and scale on the transport of a non-reactive saline tracer in a large undisturbed sandy subsoil monolith is stud- ied. The monolithique sample was extracted in a quarry at 10 m depth from the sur- face and equipped in the laboratory with tensiometers, temperature probes and time- domain-reflectometry probes. Eight solute breakthrough experiments were conducted at different flow rates allowing to elucidate the solute transport parameters in terms of a variable flow rate. The latter was controlled by means of a high precision irri- gation system in a range between 1 and 100 cm/d. Solute resident concentrations of a saline tracer was continuously monitored through 10 TDR probes of 0.4 m length, inserted in 3 vertical transects. Time series were used to estimate apparent dispersiv- ities and velocities at different locations by inversion of the analytical solution of the convection-dispersion equation for solute resident concentrations. The evolution of the apparent dispersivity with depth is studied in order to characterize the transport pro- cesses. Horizontal heterogeneity of the effective parameters is related to a mesoscale effective dispersivity factor. Furthermore, influence of the flow rate on the estimated dispersivity is also investigated.

  15. Lava Tube Flow Models at Alba Patera, Mars: Topographic Constraints on Eruption Rates

    NASA Technical Reports Server (NTRS)

    Riedel, S. J.; Sakimoto, S. E. H.; Bradley, B. A.; DeWet, A.

    2001-01-01

    Alba Patera has some of the longest lava tubes over some of the shallowest slopes on Mars. We use Mars Orbiter Laser Altimeter (MOLA) topography to model eruption rates for several Alba Patera lava tubes and compare them within Alba and with flows from other martian volcanic regions. Additional information is contained in the original extended abstract.

  16. Hot-wire sandwiched Fabry-Perot interferometer for microfluidic flow rate sensing

    NASA Astrophysics Data System (ADS)

    Li, Ying; Yan, Guofeng; Zhang, Liang; He, Sailing

    2015-08-01

    We present a Fabry-Perot interferometer for microfluidic flow rate sensing. The FPI was composed by a pair of fiber Bragg grating reflectors and a micro Co2+-doped optical fiber cavity, acting as a "hot-wire" sensor. A microfluidic channel made from commercial silica capillary was integrated with the FPIs on a chip to realize flow-rate sensing system. By utilizing a tunable pump laser with wavelength of 1480 nm, the proposed flowmeter was experimentally demonstrated. The flow rate of the liquid sample is determined by the induced resonance wavelength shift of the FPI. The effect of the pump power on the performance of our flowmeter was investigated. The dynamic response was also measured under different flow-rate conditions. The experimental results achieve a sensitivity of 70 pm/(μL/s), a dynamic range up to 1.1 μL/s and response time in the level of seconds. Such good performance renders the sensor a promising supplementary component in microfluidic biochemical sensing system.

  17. The Impact of RELAP5 Pipe Break Flow Rates Associated With Reverse Flow Limiter Removal for Steam Generator Replacement

    SciTech Connect

    Dong Zheng; Jarvis, Julie M.; Vieira, Allen T.

    2006-07-01

    Pipe break flow rates are calculated for a main feedwater line break (FWLB) in the main steam valve vault (MSVV) for a PWR Steam Generator Replacement (SGR). A reverse flow limiter is installed in the original steam generator (OSG) feedwater nozzle to limit the blowdown flowrate in the event of a postulated FWLB. This feature is not incorporated in the replacement steam generator (RSG) design. The change in RSG nozzle design in conjunction with new operating conditions results in increased FWLB mass and energy releases which can impact environmental temperatures and pressures and flooding levels. In the United States, benchmarking for safety related analyses is necessary in consideration of 10CFR50.59 requirements. RELAP5/MOD3 is used to model the pipe break flowrates for a FWLB at different break locations. The benchmark FWLB blowdown releases are larger than the OSG design basis blowdown releases due to differences in RELAP5/MOD3 versions which are found to have different algorithms for subcooled choked flow. The SGR FWLB blowdown release rates are determined to have minimal impact on the compartment temperature and pressure response. However, the flooding levels and associated equipment qualification are potentially impacted. Modeling techniques used to minimize the impact of the SGR blowdown releases on MSVV flooding levels include modeling flashing effects, more realistic RSG temperature distribution, inventory depletion and Auxiliary Feedwater (AFW) flow initiation time, and considering loss of offsite power scenarios. A detailed flooding hazard evaluation is needed, which considers the actual main feedwater isolation times to ensure that environmentally qualified safety related components, required to mitigate the effects of a FWLB inside the MSVV, can perform their safety function prior to being submerged. (authors)

  18. Observation of Oil Flow Characteristics in Rolling Piston Rotary Compressor for Reducing Oil Circulation Rate

    NASA Astrophysics Data System (ADS)

    Song, S. j.; Noh, K. Y.; Min, B. C.; Yang, J. S.; Choi, G. M.; Kim, D. J.

    2015-08-01

    The oil circulation rate (OCR) of the rolling piston rotary compressor is a significant factor which affects the performance of refrigeration system. The increase of oil discharge causes decreasing of the heat transfer efficiency in the heat exchanger, pressure drop and lack of oil in lubricate part in compressor. In this study, the internal flow of compressor was visualized to figure out the oil droplet flow characteristics. The experiments and Computational Fluid Dynamics (CFD) simulations were conducted in various frequency of compressor to observe the effect of operation frequency on oil droplet flow characteristics for reducing OCR. In situ, measurement of oil droplet diameter and velocity were conducted by using high speed image visualization and Particle Image Velocimetry (PIV). The flow paths were dominated by copper wire parts driving the motor which was inserted in compressor. In order to verify the reliability of CFD simulation, the tendency of oil flow characteristics in each flow path and the compressor operating conditions were applied in CFD simulation. For reducing OCR, the structure such as vane, disk and ring is installed in the compressor to restrict the main flow path of oil particle. The effect of additional structure for reducing OCR was evaluated using CFD simulation and the results were discussed in detail.

  19. Patterns and rates of ground-water flow on Long Island, New York

    USGS Publications Warehouse

    Buxton, Herbert T.; Modica, Edward

    1992-01-01

    Increased ground-water contamination from human activities on Long Island has prompted studies to define the pattern and rate of ground-water movement. A two-dimensional, fine-mesh, finite-element model consisting of 11,969 nodes and 22,880 elements was constructed to represent ground-water flow along a north-south section through central Long Island. The model represents average hydrologic conditions within a corridor approximately 15 miles wide. The model solves discrete approximations of both the potential and stream functions. The resulting flownet depicts flow paths and defines the vertical distribution of flow within the section. Ground-water flow rates decrease with depth. Sixty-two percent of the water flows no deeper than the upper glacial (water-table) aquifer, 38 percent enters the underlying Magothy aquifer, and only 3.1 percent enters the Lloyd aquifer. The limiting streamlines for flow to the Magothy and Lloyd aquifers indicate that aquifer recharge areas are narrow east-west bands through the center of the island. The recharge area of the Magothy aquifer is only 5.4 miles wide; that of the Lloyd aquifer is less than 0.5 miles. The distribution of ground-water traveltime and a flownet are calculated from model results; both are useful in the investigation of contaminant transport or the chemical evolution of ground water within the flow system. A major discontinuity in traveltime occurs across the streamline which separates the flow subsystems of the two confined aquifers. Water that reaches the Lloyd aquifer attains traveltimes as high as 10,000 years, whereas water that has not penetrated deeper than the Magothy aquifer attains traveltimes of only 2,000 years. The finite-element approach used in this study is particularly suited to ground-water systems that have complex hydrostratigraphy and cross-sectional symmetry.

  20. Effusion rate, length, and area relationships for some lava flows on Hawaii and Mount Etna with planetary implications

    NASA Technical Reports Server (NTRS)

    Pieri, D.; Baloga, S.

    1984-01-01

    A model for the radiative cooling of thermally well mixed lava flows is presented and the relationship between effusion rate and length and area is analyzed. If radiative cooling is the prime mode of heat loss for a lava flow, one should expect to see a stronger correlation between the effusion rate and the plan area of the flow, than between effusion rate and just flow length. Different flows on a single volcano with differing initial temperatures, volatile content, and gross compositions should yield different areas for a given effusion rate. Likewise, a range of slopes for the relationship between effusion rate and flow area should result from comparisons between different volcanoes. As a test of these ideas, available data on the effusion rates, lengths, and areas of Hawaiian and Etnean flow is studied. It was found that: (1) the effusion rate/area correlation was statistically more significant than the correlation between effusion rate and length for four out of the five eruption episodes which met the necessary criteria of more than three individual flows with area, length, and effusion rate independently measured; (2) that there exists a minimum length and area for a given effusion rate, reflecting competition between overall characteristic proportionality between effusion rate and flow length, width, and area.

  1. Saliva flow rate, buffer capacity, and pH of autistic individuals.

    PubMed

    Bassoukou, Ivy Haralambos; Nicolau, José; dos Santos, Maria Teresa

    2009-03-01

    The objective of the study was to evaluate saliva flow rate, buffer capacity, pH levels, and dental caries experience (DCE) in autistic individuals, comparing the results with a control group (CG). The study was performed on 25 noninstitutionalized autistic boys, divided in two groups. G1 composed of ten children, ages 3-8. G2 composed of 15 adolescents ages 9-13. The CG was composed of 25 healthy boys, randomly selected and also divided in two groups: CG3 composed of 14 children ages 4-8, and CG4 composed of 11 adolescents ages 9-14. Whole saliva was collected under slight suction, and pH and buffer capacity were determined using a digital pHmeter. Buffer capacity was measured by titration using 0.01 N HCl, and the flow rate expressed in ml/min, and the DCE was expressed by decayed, missing, and filled teeth (permanent dentition [DMFT] and primary dentition [dmft]). Data were plotted and submitted to nonparametric (Kruskal-Wallis) and parametric (Student's t test) statistical tests with a significance level less than 0.05. When comparing G1 and CG3, groups did not differ in flow rate, pH levels, buffer capacity, or DMFT. Groups G2 and CG4 differ significantly in pH (p = 0.007) and pHi = 7.0 (p = 0.001), with lower scores for G2. In autistic individuals aged 3-8 and 9-13, medicated or not, there was no significant statistical difference in flow rate, pH, and buffer capacity. The comparison of DCE among autistic children and CG children with deciduous (dmft) and mixed/permanent decayed, missing, and filled teeth (DMFT) did not show statistical difference (p = 0.743). Data suggest that autistic individuals have neither a higher flow rate nor a better buffer capacity. Similar DCE was observed in both groups studied. PMID:18594879

  2. Influence of mechanical rock properties and fracture healing rate on crustal fluid flow dynamics

    NASA Astrophysics Data System (ADS)

    Sachau, Till; Bons, Paul; Gomez-Rivas, Enrique; Koehn, Daniel; de Riese, Tamara

    2016-04-01

    Fluid flow in the Earth's crust is very slow over extended periods of time, during which it occurs within the connected pore space of rocks. If the fluid production rate exceeds a certain threshold, matrix permeability alone is insufficient to drain the fluid volume and fluid pressure builds up, thereby reducing the effective stress supported by the rock matrix. Hydraulic fractures form once the effective pressure exceeds the tensile strength of the rock matrix and act subsequently as highly effective fluid conduits. Once local fluid pressure is sufficiently low again, flow ceases and fractures begin to heal. Since fluid flow is controlled by the alternation of fracture permeability and matrix permeability, the flow rate in the system is strongly discontinuous and occurs in intermittent pulses. Resulting hydraulic fracture networks are largely self-organized: opening and subsequent healing of hydraulic fractures depends on the local fluid pressure and on the time-span between fluid pulses. We simulate this process with a computer model and describe the resulting dynamics statistically. Special interest is given to a) the spatially and temporally discontinuous formation and closure of fractures and fracture networks and b) the total flow rate over time. The computer model consists of a crustal-scale dual-porosity setup. Control parameters are the pressure- and time-dependent fracture healing rate, and the strength and the permeability of the intact rock. Statistical analysis involves determination of the multifractal properties and of the power spectral density of the temporal development of the total drainage rate and hydraulic fractures. References Bons, P. D. (2001). The formation of large quartz veins by rapid ascent of fluids in mobile hydrofractures. Tectonophysics, 336, 1-17. Miller, S. a., & Nur, A. (2000). Permeability as a toggle switch in fluid-controlled crustal processes. Earth and Planetary Science Letters, 183(1-2), 133-146. Sachau, T., Bons, P. D

  3. Design of an impact abrasion testing machine

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Beeley, P. R.; Baker, A. J.

    1994-04-01

    By using a cam-flat follower-impact shaft with a crank-flat rotating anvil system, the machine to be described can create various impact abrasion conditions to simulate a large range of industrial situations encountered in this field. The main features of the machine are the long working life of the flat rotating anvil, which works in the same way as that of the disk in a pin-on-disk wear tester, and the accurate control of both the impact energy delivered to the specimen and the total sliding distance of the specimen on the anvil. Statistical analysis of test results on the machine with EN24 steel and cast high manganese steel shows that the uncertainty of the population mean is within +/- 4.7% of the sample mean under a 95% confidence level of student distribution, which indicates a very good accuracy of test.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  5. Effect of different carrier gases and their flow rates on the growth of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Tewari, Aarti; Sharma, Suresh C.

    2015-04-01

    The present paper examines the effect of different carrier gases and their flow rates on the growth of carbon nanotubes (CNTs). A theoretical model is developed incorporating the charging rate of the carbon nanotube, kinetics of all the plasma species, and the growth rate of the CNTs because of diffusion and accretion of ions on the catalyst nanoparticle. The three different carrier gases, i.e., argon (Ar), ammonia, and nitrogen, are considered in the present investigation, and flow rates of all the three carrier gases are varied individually (keeping the flow rates of hydrocarbon and hydrogen gas constant) to investigate the variations in the number densities of hydrocarbon and hydrogen ions in the plasma and their consequent effects on the height and radius of CNT. Based on the results obtained, it is concluded that Ar favors the formation of CNTs with larger height and radius whereas ammonia contributes to better height of CNT but decreases the radius of CNT, and nitrogen impedes both the height and radius of CNT. The present work can serve to the better understanding of process parameters during growth of CNTs by a plasma enhanced chemical vapor deposition process.

  6. Effect of different carrier gases and their flow rates on the growth of carbon nanotubes

    SciTech Connect

    Tewari, Aarti; Sharma, Suresh C.

    2015-04-15

    The present paper examines the effect of different carrier gases and their flow rates on the growth of carbon nanotubes (CNTs). A theoretical model is developed incorporating the charging rate of the carbon nanotube, kinetics of all the plasma species, and the growth rate of the CNTs because of diffusion and accretion of ions on the catalyst nanoparticle. The three different carrier gases, i.e., argon (Ar), ammonia, and nitrogen, are considered in the present investigation, and flow rates of all the three carrier gases are varied individually (keeping the flow rates of hydrocarbon and hydrogen gas constant) to investigate the variations in the number densities of hydrocarbon and hydrogen ions in the plasma and their consequent effects on the height and radius of CNT. Based on the results obtained, it is concluded that Ar favors the formation of CNTs with larger height and radius whereas ammonia contributes to better height of CNT but decreases the radius of CNT, and nitrogen impedes both the height and radius of CNT. The present work can serve to the better understanding of process parameters during growth of CNTs by a plasma enhanced chemical vapor deposition process.

  7. Abrasion and catastrophic rupture of lunar rocks - Some implications to the micrometeoroid flux at 1 AU.

    NASA Technical Reports Server (NTRS)

    Gault, D. E.; Hoerz, F.; Hartung, J. B.

    1972-01-01

    Results from laboratory studies of hypervelocity impact against crystalline rocks, combined with estimates of the micrometeoroid flux at the lunar surface, provide a basis for calculating abrasion rates and survival times before catastrophic rupture of rocks on the lunar surface. The surface residence times observed for lunar rocks of the order of 10 m.y. (derived from the track densities of iron group nuclei) restrict the mass range of impacting particles of interest to masses less than about 1.01 gram. Extrapolation downward to smaller masses following flux distributions suggested by early satellite data and photographic meteor observations leads to absurd rates of abrasion. Consistent with the observed crater populations on the lunar rocks and with the Pegasus, Explorer, and Pioneer satellite data, the slope of the mass-flux distribution must decrease markedly for masses below 1 to .1 microgram.

  8. Use of Flow Cytometry to Measure Biogeochemical Rates and Processes in the Ocean

    NASA Astrophysics Data System (ADS)

    Lomas, Michael W.; Bronk, Deborah A.; van den Engh, Ger

    2011-01-01

    An important goal of marine biogeochemists is to quantify the rates at which elements cycle through the ocean's diverse microbial assemblage, as well as to determine how these rates vary in time and space. The traditional view that phytoplankton are producers and bacteria are consumers has been found to be overly simplistic, and environmental metagenomics is discovering new and important microbial metabolisms at an accelerating rate. Many nutritional strategies previously attributed to one microorganism or functional group are also or instead carried out by other groups. To tease apart which organism is doing what will require new analytical approaches. Flow cytometry, when combined with other techniques, has great potential for expanding our understanding of microbial interactions because groups can be distinguished optically, sorted, and then collected for subsequent analyses. Herein, we review the advances in our understanding of marine biogeochemistry that have arisen from the use of flow cytometry.

  9. Determining the Sun's Deep Meridional Flow Speed Using Active Latitude Drift Rates Since 1874

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Wilson, Robert M.

    2005-01-01

    Dynamo models that incorporate a deep meridional return flow indicate that this flow regulates both the period and the amplitude of the sunspot cycle. We recently examined the equatorward drift of the active latitudes (as given by the centroid of the sunspot areas in each hemisphere) and found evidence supporting this view. In those studies we fit the equatorward drift in each hemisphere for each sunspot cycle with a simple parabola - giving us a drift rate and its deceleration for each hemisphere/cycle. Here we analyze the same data (the Royal Greenwich Observatory/JSAF/NOAA daily active region summaries) to determine the drift rates in each hemisphere on a yearly basis (rotation-by- rotation measurements smoothed to remove high frequencies) and fit them with a simple model for the meridional flow that provides the meridional flow speed as a function of latitude and time from 1874 to 2005. These flow speeds can be used to test dynamo models - some of which have predictive capabilities.

  10. On the relationship between the rate of salivary flow and salivary fluoride clearance.

    PubMed

    Duckworth, Ralph M; Jones, S

    2015-01-01

    The amount of fluoride retained in the mouth following the application of dentifrices, mouthwashes, etc. may be important in determining their anticaries efficacy. In this study we investigated the relationship between the salivary flow rate and salivary fluoride clearance. Ten adults tested six mouthrinses, consisting of aqueous sodium fluoride solutions (0.013, 0.026 mol/l) with and without added sodium chloride (1.28 mol/l) or sucrose (0.44 mol/l), in a randomised order. Prior to each test, subjects swallowed, rinsed for 2 min with 2 ml water and then expectorated into a preweighed container to obtain a measure of initial saliva flow rate. Next, the procedure was repeated using one of the test rinses. Finally, samples of unstimulated whole saliva were collected for up to 3 h after each mouthrinse application and analysed for fluoride. Salivary fluoride concentrations were significantly lower after application of mouthrinses that contained either sucrose or NaCl, both of which compounds markedly enhanced salivary flow, than after the use of corresponding mouthrinses without any additive. Area under the salivary fluoride clearance curve (AUC) values were inversely correlated with salivary flow rate on an individual basis (p < 0.01). The observed behaviour could not be completely attributed to treatment dilution by saliva at the time of application. PMID:25634162

  11. Grain-size-independent plastic flow at ultrahigh pressures and strain rates.

    PubMed

    Park, H-S; Rudd, R E; Cavallo, R M; Barton, N R; Arsenlis, A; Belof, J L; Blobaum, K J M; El-dasher, B S; Florando, J N; Huntington, C M; Maddox, B R; May, M J; Plechaty, C; Prisbrey, S T; Remington, B A; Wallace, R J; Wehrenberg, C E; Wilson, M J; Comley, A J; Giraldez, E; Nikroo, A; Farrell, M; Randall, G; Gray, G T

    2015-02-13

    A basic tenet of material science is that the flow stress of a metal increases as its grain size decreases, an effect described by the Hall-Petch relation. This relation is used extensively in material design to optimize the hardness, durability, survivability, and ductility of structural metals. This Letter reports experimental results in a new regime of high pressures and strain rates that challenge this basic tenet of mechanical metallurgy. We report measurements of the plastic flow of the model body-centered-cubic metal tantalum made under conditions of high pressure (>100  GPa) and strain rate (∼10(7)  s(-1)) achieved by using the Omega laser. Under these unique plastic deformation ("flow") conditions, the effect of grain size is found to be negligible for grain sizes >0.25  μm sizes. A multiscale model of the plastic flow suggests that pressure and strain rate hardening dominate over the grain-size effects. Theoretical estimates, based on grain compatibility and geometrically necessary dislocations, corroborate this conclusion. PMID:25723227

  12. Effects of saline-water flow rate and air speed on leakage current in RTV coatings

    SciTech Connect

    Kim, S.H.; Hackam, R.

    1995-10-01

    Room temperature vulcanizing (RTV) silicone rubber is increasingly being used to coat porcelain and glass insulators in order to improve their electrical performance in the presence of pollution and moisture. A study of the dependence of leakage current, pulse current count and total charge flowing across the surface of RTV on the flow rate of the saline water and on the compressed air pressure used to create the salt-fog is reported. The fog was directed at the insulating rods either from one or two sides. The RTV was fabricated from polydimethylsiloxane polymer, a filler of alumina trihydrate (ATH), a polymerization catalyst and fumed silica reinforcer, all dispersed in 1,1,1-trichloroethane solvent. The saline water flow rate was varied in the range 0.4 to 2.0 l/min. The compressed air pressure at the input of the fog nozzles was varied from 0.20 to 0.63 MPa. The air speed at the surface of the insulating rods was found to depend linearly on the air pressure measured at the inlet to the nozzles and varied in the range 3 to 14 km/hr. The leakage current increased with increasing flow rate and increasing air speed. This is attributed to the increased loss of hydrophobicity with a larger quantity of saline fog and a larger impact velocities of fog droplets interacting with the surface of the RTV coating.

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

    NASA Astrophysics Data System (ADS)

    Kwon, Kilsugn; Han, Jaesuk; Kim, Daejoong

    2013-11-01

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

  14. Changes in Advective Flow Rates and Flow Paths in Response to Earthquakes Recorded by Japan Trench Subseafloor Temperature Observations

    NASA Astrophysics Data System (ADS)

    Fulton, P. M.; Brodsky, E. E.; Kano, Y.; Mori, J. J.; Chester, F. M.; Eguchi, N.; Toczko, S.

    2013-12-01

    In July 2012, the JFAST project (IODP Expedition 343/343T) installed a temperature observatory across the fault that generated the March 2011 Mw9.0 Tohoku earthquake. The observatory consisted of 55 temperature-sensing dataloggers with <0.001°C resolution attached to a rope extending 820 m beneath the seafloor in a fully cased 3.5' inner diameter borehole. Sensor spacing varied from 1.3 to 9 m over the lowermost ~150 m. Most measurements were taken every 10 seconds - 10 minutes depending on the instrument. Ten of the instruments also recorded pressure at <1000 Pa resolution to provide control on sensor depths. The sensor string and data were recovered after a 9-month deployment in April 2013. In addition to monitoring a frictional heat signal across the plate boundary fault from slip during the 11 March 2011 Tohoku Earthquake, signatures of advective fluid flow are observed within a damage zone at shallower depths. These advective signals appear as transient temperature anomalies above the background geotherm and have large spatially-correlative variability suggestive of fluctuations in fluid flow rate. The advective signals also correspond with locations inferred to have high permeability on the basis of prolonged decay time of drilling disturbances. The locations are also consistent with a zone of steeply-dipping open faults or fractures identified by logging data in an adjacent borehole ~30 m away along strike. The plate boundary fault at 818 mbsf inferred to have slipped during the Tohoku Earthquake shows no indication of advective fluid flow or high permeability. On December 7, 2012, in the middle of the experiment, a Mw7.4 earthquake occurred very close to the observatory. While this earthquake occurred at a depth below the plate boundary fault, it had a clear effect on the hydrogeology and temperatures monitored by the observatory. An advective signal observed at 784 mbsf immediately begins to decay following the earthquake and reappears at 763 mbsf with a

  15. The Mitral Valve Prolapsus: Quantification of the Regurgitation Flow Rate by Experimental Time-Dependant PIV

    NASA Astrophysics Data System (ADS)

    Billy, F.; Coisne, D.; Sanchez, L.; Perrault, R.

    2001-10-01

    Color Doppler is routinely used for visualisation of intra cardiac flows and quantification of valvular heart disease, Nevertheless the 2D visualization of a complex 3D phenomenon is the major limitation of this technique, In particular, in clinical setting, the flow rate calculation upstream a regurgitant orifice (i,e, mitral valve insufficiency), assumes that the velocity field in the convergent region have hemispheric shapes and introduce miscalculation specially in case of prolaps regurgitant orifices, The main objective of this study was to characterize the dynamic 3D velocity field of the convergent region upstream a prolaps model of regurgitant orifice based on 2D time dependent PIV reconstruction.

  16. Flow Rate Driven by Peristaltic Movement in Plasmodial Tube of Physarum Polycephalum

    NASA Astrophysics Data System (ADS)

    Yamada, Hiroyasu; Nakagaki, Toshiyuki

    2008-07-01

    We report a theoretical analysis of protoplasmic streaming driven by peristaltic movement in an elastic tube of an amoeba-like organism. The Plasmodium of Physarum polycephalum, a true slime mold, is a large amoeboid organism that adopts a sheet-like form with a tubular network. The network extends throughout the Plasmodium and enables the transport and circulation of chemical signals and nutrients. This tubular flow is driven by periodically propagating waves of active contraction of the tube cortex, a process known as peristaltic movement. We derive the relationship between the phase velocity of the contraction wave and the flow rate, and we discuss the physiological implications of this relationship.

  17. Mass flow rate of granular material in silos with lateral exit holes

    NASA Astrophysics Data System (ADS)

    Medina, Abraham; Serrano, Armando; Sanchez, Florencio

    2014-11-01

    In this work we have analyzed experimentally the mass flow rate, m', of the lateral outflow of cohesionless granular material through circular orifices of diameter D and rectangular and triangular slots of hydraulic diameter DH made in vertical walls of bins. Experiments were made in order to determine also the influence of the wall thickness of the bin, w. Geometrical and physical arguments, are given to get a general correlation for m' embracing both quantities, D (DH) and w. The angle of repose is also an important factor characterizing these flows.

  18. Tuning-free controller to accurately regulate flow rates in a microfluidic network

    NASA Astrophysics Data System (ADS)

    Heo, Young Jin; Kang, Junsu; Kim, Min Jun; Chung, Wan Kyun

    2016-03-01

    We describe a control algorithm that can improve accuracy and stability of flow regulation in a microfluidic network that uses a conventional pressure pump system. The algorithm enables simultaneous and independent control of fluid flows in multiple micro-channels of a microfluidic network, but does not require any model parameters or tuning process. We investigate robustness and optimality of the proposed control algorithm and those are verified by simulations and experiments. In addition, the control algorithm is compared with a conventional PID controller to show that the proposed control algorithm resolves critical problems induced by the PID control. The capability of the control algorithm can be used not only in high-precision flow regulation in the presence of disturbance, but in some useful functions for lab-on-a-chip devices such as regulation of volumetric flow rate, interface position control of two laminar flows, valveless flow switching, droplet generation and particle manipulation. We demonstrate those functions and also suggest further potential biological applications which can be accomplished by the proposed control framework.

  19. Tuning-free controller to accurately regulate flow rates in a microfluidic network.

    PubMed

    Heo, Young Jin; Kang, Junsu; Kim, Min Jun; Chung, Wan Kyun

    2016-01-01

    We describe a control algorithm that can improve accuracy and stability of flow regulation in a microfluidic network that uses a conventional pressure pump system. The algorithm enables simultaneous and independent control of fluid flows in multiple micro-channels of a microfluidic network, but does not require any model parameters or tuning process. We investigate robustness and optimality of the proposed control algorithm and those are verified by simulations and experiments. In addition, the control algorithm is compared with a conventional PID controller to show that the proposed control algorithm resolves critical problems induced by the PID control. The capability of the control algorithm can be used not only in high-precision flow regulation in the presence of disturbance, but in some useful functions for lab-on-a-chip devices such as regulation of volumetric flow rate, interface position control of two laminar flows, valveless flow switching, droplet generation and particle manipulation. We demonstrate those functions and also suggest further potential biological applications which can be accomplished by the proposed control framework. PMID:26987587

  20. Tuning-free controller to accurately regulate flow rates in a microfluidic network

    PubMed Central

    Heo, Young Jin; Kang, Junsu; Kim, Min Jun; Chung, Wan Kyun

    2016-01-01

    We describe a control algorithm that can improve accuracy and stability of flow regulation in a microfluidic network that uses a conventional pressure pump system. The algorithm enables simultaneous and independent control of fluid flows in multiple micro-channels of a microfluidic network, but does not require any model parameters or tuning process. We investigate robustness and optimality of the proposed control algorithm and those are verified by simulations and experiments. In addition, the control algorithm is compared with a conventional PID controller to show that the proposed control algorithm resolves critical problems induced by the PID control. The capability of the control algorithm can be used not only in high-precision flow regulation in the presence of disturbance, but in some useful functions for lab-on-a-chip devices such as regulation of volumetric flow rate, interface position control of two laminar flows, valveless flow switching, droplet generation and particle manipulation. We demonstrate those functions and also suggest further potential biological applications which can be accomplished by the proposed control framework. PMID:26987587

  1. Effect of actuation sequence on flow rates of peristaltic micropumps with PZT actuators.

    PubMed

    Jang, Ling-Sheng; Shu, Kuan; Yu, Yung-Chiang; Li, Yuan-Jie; Chen, Chiun-Hsun

    2009-02-01

    Many biomedical applications require the administration of drugs at a precise and preferably programmable rate. The flow rate generated by the peristaltic micropumps used in such applications depends on the actuation sequence. Accordingly, the current study performs an analytical and experimental investigation to determine the correlation between the dynamic response of the diaphragms in the micropump and the actuation sequence. A simple analytical model of a peristaltic micropump is established to analyze the shift in the resonant frequency of the diaphragms caused by the viscous damping effect. The analytical results show that this damping effect increases as the oscillation frequency of the diaphragm increases. A peristaltic micropump with three piezoelectric actuators is fabricated on a silicon substrate and is actuated using 2-, 3-, 4- and 6-phase actuation sequences via a driving system comprising a microprocessor and a phase controller. A series of experiments is conducted using de-ionized water as the working fluid to determine the diaphragm displacement and the flow rates induced by each of the different actuation sequences under phase frequencies ranging from 50 Hz to 1 MHz. The results show that the damping effect of actuation sequences influences diaphragm resonant frequency, which in turn affects the profiles of flow rates. PMID:18821016

  2. Effect of simple shear flow on photosynthesis rate and morphology of micro algae

    NASA Astrophysics Data System (ADS)

    Mitsuhashi, S.; Fujimoto, M.; Muramatsu, H.; Tanishita, K.

    The convective motion of micro algal suspension gives an advantageous effect on the photosynthetic rate in the bioreactor, however, the nature of convective effect on the photosynthesis has not been fully understood. The propose of this study concerns the nature of photosynthetic rate in a well-defined hydrodynamic shear flow of Spirulina platensis suspension, generated in a double rotating coaxial cylinders. The double rotating coaxial cylinders was installed in the incubator chamber with the controlled illumination intensity and temperature. Two kind of experiments, short and long term experiments, were performed to evaluate the direct effect of shear flow on the photosynthetic rate. The short term experiment indicates that the simple shear flow enables to augment the photosynthesis of Spirulina suspension and simultaneously causes the cell destruction due to the excessive shear stress. The long term experiment for 100 hours reveals that the growth rate and the morphology of Spirulina is sensitive to the external fluid mechanical stimulus. The long term application of mechanical stress on the algae may result in the adaptation of the photosynthetic function and morphology.

  3. Primary standard for liquid flow rates between 30 and 1500 nl/min based on volume expansion.

    PubMed

    Lucas, Peter; Ahrens, Martin; Geršl, Jan; Sparreboom, Wouter; Lötters, Joost

    2015-08-01

    An increasing number of microfluidic systems operate at flow rates below 1 μl/min. Applications include (implanted) micropumps for drug delivery, liquid chromatography, and microreactors. For the applications where the absolute accuracy is important, a proper calibration is required. However, with standard calibration facilities, flow rate calibrations below ~1 μl/min are not feasible because of a too large calibration uncertainty. In the current research, a traceable flow rate using a certain temperature increase rate is proposed. When the fluid properties, starting mass, and temperature increase rate are known, this principle yields a direct link to SI units, which makes it a primary standard. In this article, it will be shown that this principle enables flow rate uncertainties in the order of 2-3% for flow rates from 30 to 1500 nl/min. PMID:26352350

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

    NASA Astrophysics Data System (ADS)

    Perks, Matthew; Large, Andy; Russell, Andy

    2015-04-01

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

  5. Method for forming an abrasive surface on a tool

    DOEpatents

    Seals, Roland D.; White, Rickey L.; Swindeman, Catherine J.; Kahl, W. Keith

    1999-01-01

    A method for fabricating a tool used in cutting, grinding and machining operations, is provided. The method is used to deposit a mixture comprising an abrasive material and a bonding material on a tool surface. The materials are propelled toward the receiving surface of the tool substrate using a thermal spray process. The thermal spray process melts the bonding material portion of the mixture, but not the abrasive material. Upon impacting the tool surface, the mixture or composition solidifies to form a hard abrasive tool coating.

  6. Determining Flow Type and Shear Rate in Magmas From Bubble Shapes and Orientations

    NASA Astrophysics Data System (ADS)

    Rust, A. C.; Manga, M.; Cashman, K. V.

    2001-12-01

    To compare bubble geometries in obsidian to bubbles deformed under known conditions, we measure the deformation of air bubbles in corn syrup in simple shear. We use these experimental data and results of theoretical, numerical and experimental studies to interpret the shear environments that formed the textures preserved in obsidian samples. In particular, we use the shapes and orientations of bubbles in obsidian to estimate shear rates and assess flow type (simple vs. pure shear). This technique can be used to determine shear rates in volcanic conduits, the origin of pyroclastic obsidian, and the emplacement history and dynamics of obsidian flows. The deformation of a bubble is governed by the competing stresses from shearing that deforms, and surface tension that rerounds. The ratio of these stresses is the capillary number, Ca. An initially spherical bubble placed in a low Reynolds number, steady flow field deforms with a time-dependent shape and orientation until it reaches a steady geometry or breaks into smaller bubbles. A useful measure of the magnitude of flow-induced bubble deformation is the dimensionless parameter, D=(l-b)/(l+b) where l and b are the semi-major and semi-minor axes of the sheared bubble. For small deformations (Ca<< 1), low Reynolds number flow and bubble viscosity << suspending fluid viscosity, D ~ 2 Ca in pure shear and D ~ Ca in simple shear. In pure shear flow, bubble elongations are parallel to the shear direction regardless of the magnitude of bubble deformation. However, in simple shear flow, the angle between the bubble elongation and the flow varies with Ca, which is proportional to bubble radius and shear rate. Because the relationships between Ca and bubble orientation and shape for pure and simple shear differ, we can distinguish between these flow types using bubble geometries preserved in obsidian. Furthermore, because Ca is a function of shear rate, we can use relationships between Ca and D to calculate shear rates when

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  8. Maximum two-phase flow rates of subcooled nitrogen through a sharp-edged orifice

    NASA Technical Reports Server (NTRS)

    Simoneau, R. J.

    1975-01-01

    An experiment was conducted and data are presented in which subcooled liquid nitrogen was discharged through a sharp-edged orifice at flow rates near the maximum. The data covered a range of inlet stagnation pressure from slightly above saturation to twice the thermodynamic critical pressure. The data were taken along five separate inlet stagnation isotherms ranging from 0.75 to 1.035 times the thermodynamic critical temperature. The results indicate that: (1) subcooled liquids do not choke or approach maximum flow in an asymptotic manner even though the back pressure is well below saturation; (2) orifice flow coefficients are not constant as is frequently assumed. A metastable jet appears to exist which breaks down if the difference between back pressure and saturation pressure is large enough.

  9. Maximum two-phase flow rates of subcooled nitrogen through a sharp-edged orifice

    NASA Technical Reports Server (NTRS)

    Simoneau, R. J.

    1975-01-01

    Data are presented of an experiment in which subcooled liquid nitrogen was discharged through a sharp-edged orifice at flow rates near the maximum. The data covered a range of inlet stagnation pressures from slightly above saturation to twice the thermodynamic critical pressure. The data were taken along five separate inlet stagnation isotherms ranging from 0.75 to 1.035 times the thermodynamic critical temperature. The results indicate that subcooled liquids do not choke or approach maximum flow in an asymptotic manner even though the back pressure is well below saturation; and orifice flow coefficients are not constant as is frequently assumed. A metastable jet appears to exist which breaks down if the difference between back pressure and saturation pressure is large enough.

  10. Autoregulation of renal blood flow and glomerular filtration rate in the pregnant rabbit

    SciTech Connect

    Woods, L.L.; Mizelle, H.L.; Hall, J.E.

    1987-01-01

    The authors purpose was to determine whether renal autoregulatory capability is retained in pregnancy despite the marked renal vasodilation that occurs at this time. Renal blood flow and glomerular filtration rate (GFR) were measured in anesthetized pregnant (22-27 days gestation) and nonpregnant rabbits during step reductions in renal perfusion pressure from control (100 +/- 3 mmHg) to 50 mmHg. Control renal blood flow and GFR were significantly higher in pregnant animals. Filtration fraction was also significantly elevated in pregnant animals. During step reductions in renal perfusion pressure, renal blood flow was well autoregulated down to approx.70 mmHg in both nonpregnant and pregnant animals. Likewise, GFR was also well autoregulated, falling by 10 +/- 2 and 8 +/- 3% in nonpregnant and pregnant animals, respectively, when perfusion pressure was reduced from 90 to 70 mmHg. These results suggest that renal autoregulation is preserved in pregnancy despite the fact that the renal circulation is already markedly vasodilated.

  11. Body surface related flow rate nomograms in a normal pediatric population.

    PubMed

    Wese, F X; Gaum, L D; Liu, T P; Wong, A K; Hardy, B E; Churchill, B M

    1989-01-01

    Uroflow studies for 511 normal pediatric subjects (272 boys, 239 girls) were analyzed statistically. Nomograms relating peak flow to volume voided and body surface were established. An acceptable lower limit for peak flow was obtained from the data and a volume voided range was calculated so that both criteria could be used with 90% probability to define the normal voiding situation. Body surface area was found to be a more reliable index than age in the establishment of nomograms. In the male population the 90% probability applied to a significantly greater volume voided reliability. In the female population mean peak flow rate rose with increased body surface. Finally, in both sexes the 10% lower limit was closer to the regression mean, allowing a tighter distribution around this value. PMID:2763926

  12. Abrasive Wear Resistance of Tool Steels Evaluated by the Pin-on-Disc Testing

    NASA Astrophysics Data System (ADS)

    Bressan, José Divo; Schopf, Roberto Alexandre

    2011-05-01

    Present work examines tool steels abrasion wear resistance and the abrasion mechanisms which are one main contributor to failure of tooling in metal forming industry. Tooling used in cutting and metal forming processes without lubrication fails due to this type of wear. In the workshop and engineering practice, it is common to relate wear resistance as function of material hardness only. However, there are others parameters which influences wear such as: fracture toughness, type of crystalline structure and the occurrence of hard precipitate in the metallic matrix and also its nature. In the present investigation, the wear mechanisms acting in tool steels were analyzed and, by normalized tests, wear resistance performance of nine different types of tool steels were evaluated by pin-on-disc testing. Conventional tool steels commonly used in tooling such as AISI H13 and AISI A2 were compared in relation to tool steels fabricated by sintering process such as Crucible CPM 3V, CPM 9V and M4 steels. Friction and wear testing were carried out in a pin-on-disc automated equipment which pin was tool steel and the counter-face was a abrasive disc of silicon carbide. Normal load of 5 N, sliding velocity of 0.45 m/s, total sliding distance of 3000 m and room temperature were employed. The wear rate was calculated by the Archard's equation and from the plotted graphs of pin cumulated volume loss versus sliding distance. Specimens were appropriately heat treated by quenching and three tempering cycles. Percentage of alloying elements, metallographic analyses of microstructure and Vickers microhardness of specimens were performed, analyzed and correlated with wear rate. The work is concluded by the presentation of a rank of tool steel wear rate, comparing the different tool steel abrasion wear resistance: the best tool steel wear resistance evaluated was the Crucible CPM 9V steel.

  13. New Rock Abrasivity Test Method for Tool Life Assessments on Hard Rock Tunnel Boring: The Rolling Indentation Abrasion Test (RIAT)

    NASA Astrophysics Data System (ADS)

    Macias, F. J.; Dahl, F.; Bruland, A.

    2016-05-01

    The tunnel boring machine (TBM) method has become widely used and is currently an important presence within the tunnelling industry. Large investments and high geological risk are involved using TBMs, and disc cutter consumption has a great influence on performance and cost, especially in hard rock conditions. Furthermore, reliable cutter life assessments facilitate the control of risk as well as avoiding delays and budget overruns. Since abrasive wear is the most common process affecting cutter consumption, good laboratory tests for rock abrasivity assessments are needed. A new abrasivity test method by rolling disc named Rolling Indentation Abrasion Test (RIAT) has been developed. The goal of the new test design and procedure is to reproduce wear behaviour on hard rock tunnel boring in a more realistic way than the traditionally used methods. Wear by rolling contact on intact rock samples is introduced and several rock types, covering a wide rock abrasiveness range, have been tested by RIAT. The RIAT procedure indicates a great ability of the testing method to assess abrasive wear on rolling discs. In addition and to evaluate the newly developed RIAT test method, a comprehensive laboratory testing programme including the most commonly used abrasivity test methods and the mineral composition were carried out. Relationships between the achieved results from conventional testing and RIAT results have been analysed.

  14. Hydrodechlorination of TCE in a circulated electrolytic column at high flow rate.

    PubMed

    Fallahpour, Noushin; Yuan, Songhu; Rajic, Ljiljana; Alshawabkeh, Akram N

    2016-02-01

    Palladium-catalytic hydrodechlorination of trichloroethylene (TCE) by cathodic H2 produced from water electrolysis has been tested. For a field in-well application, the flow rate is generally high. In this study, the performance of Pd-catalytic hydrodechlorination of TCE using cathodic H2 is evaluated under high flow rate (1 L min(-1)) in a circulated column system, as expected to occur in practice. An iron anode supports reduction conditions and it is used to enhance TCE hydrodechlorination. However, the precipitation occurs and high flow rate was evaluated to minimize its adverse effects on the process (electrode coverage, clogging, etc.). Under the conditions of 1 L min(-1) flow, 500 mA current, and 5 mg L(-1) initial TCE concentration, removal efficacy using iron anodes (96%) is significantly higher than by mixed metal oxide (MMO) anodes (66%). Two types of cathodes (MMO and copper foam) in the presence of Pd/Al2O3 catalyst under various currents (250, 125, and 62 mA) were used to evaluate the effect of cathode materials on TCE removal efficacy. The similar removal efficiencies were achieved for both cathodes, but more precipitation generated with copper foam cathode (based on the experiments done by authors). In addition to the well-known parameters such as current density, electrode materials, and initial TCE concentration, the high velocities of groundwater flow can have important implications, practically in relation to the flush out of precipitates. For potential field application, a cost-effective and sustainable in situ electrochemical process using a solar panel as power supply is being evaluated. PMID:26344148

  15. The Cooling Rate of an Active Aa Lava Flow Determined Using an Orbital Imaging Spectrometer

    NASA Astrophysics Data System (ADS)

    Wright, Robert; Garbeil, Harold

    2010-05-01

    The surface temperature of an active lava flow is an important physical property to measure. Through its influence on lava crystallinity, cooling exerts a fundamental control on lava rheology. Remotely sensed thermal radiance data acquired by multispectral sensors such as Landsat Thematic Mapper and the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer, are of insufficient spectral and radiometric fidelity to allow for realistic determination of lava surface temperatures from Earth orbit. This paper presents results obtained from the analysis of active lava flows using hyperspectral data acquired by NASA's Earth Observing-1 Hyperion imaging spectrometer. The contiguous nature of the measured radiance spectrum in the 0.4-2.5 micron region means that, although sensor saturation most certainly occurs, unsaturated radiance data are always available from even the hottest, and most radiant, active lava flow surfaces. The increased number of wavebands available allows for the assumption of more complex flow surface temperature distributions in the radiance-to-temperature inversion processes. The technique is illustrated by using a hyperspectral image of the active lava lake at Erta Ale volcano, Ethiopia, a well characterized calibration target. We then go on to demonstrate how this approach can be used to constrain the surface cooling rate of an active lava flow at Mount Etna, Sicily, using three images acquired during a four day period in September 2004. The cooling rate of the active channel as determined from space falls within the limits commonly assumed in numerical lava flow models. The results provide insights into the temperature-radiance mixture modeling problem that will aid in the analysis of data acquired by future hyperspectral remote sensing missions, such as NASA's proposed HyspIRI mission.

  16. Definition of hydraulic stability of KVGM-100 hot-water boiler and minimum water flow rate

    NASA Astrophysics Data System (ADS)

    Belov, A. A.; Ozerov, A. N.; Usikov, N. V.; Shkondin, I. A.

    2016-08-01

    In domestic power engineering, the methods of quantitative and qualitative-quantitative adjusting the load of the heat supply systems are widely distributed; furthermore, during the greater part of the heating period, the actual discharge of network water is less than estimated values when changing to quantitative adjustment. Hence, the hydraulic circuits of hot-water boilers should ensure the water velocities, minimizing the scale formation and excluding the formation of stagnant zones. The results of the calculations of hot-water KVGM-100 boiler and minimum water flow rate for the basic and peak modes at the fulfillment of condition of the lack of surface boil are presented in the article. The minimal flow rates of water at its underheating to the saturation state and the thermal flows in the furnace chamber were defined. The boiler hydraulic calculation was performed using the "Hydraulic" program, and the analysis of permissible and actual velocities of the water movement in the pipes of the heating surfaces was carried out. Based on the thermal calculations of furnace chamber and thermal- hydraulic calculations of heating surfaces, the following conclusions were drawn: the minimum velocity of water movement (by condition of boiling surface) at lifting movement of environment increases from 0.64 to 0.79 m/s; it increases from 1.14 to 1.38 m/s at down movement of environmental; the minimum water flow rate by the boiler in the basic mode (by condition of the surface boiling) increased from 887 t/h at the load of 20% up to 1074 t/h at the load of 100%. The minimum flow rate is 1074 t/h at nominal load and is achieved at the pressure at the boiler outlet equal to 1.1 MPa; the minimum water flow rate by the boiler in the peak mode by condition of surface boiling increases from 1669 t/h at the load of 20% up to 2021 t/h at the load of 100%.

  17. Effect of Flow Rate of Side-Type Orifice Intake on Withdrawn Water Temperature

    PubMed Central

    Li, Guangning

    2014-01-01

    Side-type orifice intake is a type of selective withdrawal facility used in managing reservoirs to mitigate the negative effects of low-temperature water. Based on the temperature data of a thermal stratified reservoir in China, an experiment was conducted in flume to study the influence of intake flow rate on withdrawn water temperature with different temperature distributions. Results indicated that withdrawn water temperature changed with different flow rates. The temperature change was determined by the water temperature gradients above and below the intake, whereas the change trend of temperature depended on the difference between the water temperature gradient above and below the intake. We likewise proposed a new equation with which the withdrawn water temperature of a thermal stratified reservoir using a side-type orifice could be calculated. These findings could be directly applied to the design and operation of side-type orifice intake in thermal stratified reservoirs. PMID:25019100

  18. The dynamic behavior of articulated pipes conveying fluid with periodic flow rate.

    NASA Technical Reports Server (NTRS)

    Bohn, M. P.; Herrmann, G.

    1973-01-01

    The plane motion of two rigid, straight articulated pipes conveying fluid is examined. In contrast to previous work, the flow rate is not taken as constant, but is allowed to have small periodic oscillations about a mean value, as would be expected in a pump-driven system. It is shown that in the presence of such disturbances, both parametric and combination resonances are possible. When the system can also admit loss of stability by static buckling or by flutter, it is found that the presence of small periodic disturbances constitutes a destabilizing effect. Floquet theory and converging infinite determinant expansions are used to illustrate a basic difference between systems which lose stability by divergence and those that lose stability by flutter. An algebraic criterion is obtained for the minimum amplitude of flow-rate oscillation required for the system to be affected by the presence of small disturbances.

  19. THEORETICAL ANALYSIS OF THE TRANSIENT PRESSURE RESPONSE FROM A CONSTANT FLOW RATE HYDRAULIC CONDUCTIVITY TEST.

    USGS Publications Warehouse

    Morin, Roger H.; Olsen, Harold W.

    1987-01-01

    Incorporating a flow pump into a conventional triaxial laboratory system allows fluid to be supplied to or withdrawn from the base of a sediment sample at small and constant rates. An initial transient record of hydraulic head versus time is observed which eventually stabilizes to a constant steady state gradient across the sample; values of hydraulic conductivity can subsequently be determined from Darcy's law. In this paper, analytical methods are presented for determining values of specific storage and hydraulic conductivity from the initial transient phase of such a constant flow rate test. These methods are based on a diffusion equation involving pore pressure and are analogous to those used to describe the soil consolidation process and also to interpret aquifer properties from pumping tests.

  20. Noise-induced convergence of the low flow rate chaos in the Belousov-Zhabotinsky reaction

    NASA Astrophysics Data System (ADS)

    Yoshimoto, Minoru; Nakaiwa, Masaru; Akiya, Takaji; Ohmori, Takao; Yamaguchi, Tomohiko

    The effect of noise on the low flow-rate chaos in the Belousov-Zhabotinsky (BZ) reaction was studied. The chaos was simulated using the three-variable model of Györgyi and Field. Gaussian white noise was imposed on the flow-rate of the reactant solutions fed into CSTR to simulate the so-called type P noise. The range of average noise amplitudes was chosen between 0.01% and 1% related to the inverse residence time. The calculated time series were analyzed on the basis of their Fourier spectra, maximum Lyapunov exponent, Kolmogorov entropies, return maps and invariant density. We found that the noise induces partial order of the period-3-like oscillations in the low flowrate chaos.

  1. Measurement of gas yields and flow rates using a custom flowmeter

    USGS Publications Warehouse

    Circone, S.; Kirby, S.H.; Pinkston, J.C.; Stern, L.A.

    2001-01-01

    A simple gas collection apparatus based on the principles of a Torricelli tube has been designed and built to measure gas volume yields and flow rates. This instrument is routinely used to monitor and collect methane gas released during methane hydrate dissociation experiments. It is easily and inexpensively built, operates at ambient pressures and temperatures, and measures gas volumes of up to 7 L to a precision of about 15 ml (about 0.0025 mol). It is capable of measuring gas flow rates varying from more than 103 to less than 10-1 ml/min during gas evolution events that span minutes to several days. We have obtained a highly reproducible hydrate number of n=5.891 with a propagated uncertainty of ??0.020 for synthetic methane hydrate. ?? 2001 American Institute of Physics.

  2. Flow rate and slip length measurements of water in single micrometer pipes

    NASA Astrophysics Data System (ADS)

    Taborek, Peter; Kannan, Anerudh; Mallin, David; Velasco, Angel

    2014-11-01

    Measurements of pressure driven water flows in hydrophobic and hydrophilic fused quartz capillaries of 1.8 um diameter are compared. Typical flow rates of 1 picoliter/s and pressure drops up to 25 Atm were used. Water exited the capillaries into an oil reservoir where the volume of the pendant drop could be monitored using time lapse photography. The typical growth rate for the drop diameter was ~300 μm per day. The drop size saturates due to diffusion at the interface. For the untreated quartz capillary the results are consistent with a slip of zero. The hydrophilic capillaries are chemically treated with octadecyltrichlorosilane (OTS) to form hydrophobic surfaces. Successful surface preparation is confirmed with the absence of capillary rise. Our technique can detect slip lengths above 20 nm.

  3. Assessment of glomerular filtration rate and effective renal plasma flow in cystic fibrosis

    SciTech Connect

    Spino, M.; Chai, R.P.; Isles, A.F.; Balfe, J.W.; Brown, R.G.; Thiessen, J.J.; MacLeod, S.M.

    1985-07-01

    A study was conducted to examine renal function in 10 healthy control subjects and eight patients with cystic fibrosis in stable condition. Sequential bolus injections of /sup 99m/Tc-DTPA and /sup 125/I-OIH were administered to assess glomerular filtration rate and effective renal plasma flow, respectively. Blood was subsequently collected for 3 hours, and urine for 24 hours. Renal clearances of both radioisotope markers were virtually identical in patients and controls. Inasmuch as neither glomerular filtration rate nor effective renal plasma flow was enhanced in patients with cystic fibrosis, increased clearance of drugs in these patients is unlikely to be the result of enhanced glomerular filtration or tubular secretion.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  5. Entrained liquid fraction calculation in adiabatic disperse-annular flows at low rate in film

    NASA Astrophysics Data System (ADS)

    Yagov, V. V.; Minko, M. V.

    2016-04-01

    In this work, we continue our study [1] and extend further an approach to low reduced pressures. An approximate model of droplets entrainment from the laminar film surface and an equation for calculating entrainment intensity are proposed. To carry out direct verification of this equation using experimental data is extremely difficult because the integral effect—liquid flow rate in a film at a dynamic equilibrium between entrainment and deposition—is usually measured in the experiments. The balance between flows of droplets entrainment and deposition corresponds to the dynamic equilibrium because of turbulent diffusion. The transcendental equation, which was obtained on the basis of this balance, contains one unknown numerical factor and allows one to calculate the liquid rate. Comparing calculation results with the experimental data for the water-air and water-helium flows at low reduced pressures (less than 0.03) has shown their good agreement at the universal value of a numerical constant, if an additional dimensionless parameter, a fourth root of vaporliquid densities ratio, is introduced. The criterion that determines the boundary of using methods of this work and that of [1] in calculations and that reflects effect of pressure and state of film surface on distribution of the liquid in the annular flow is proposed; the numerical value of this criterion has been determined.

  6. Granular-flow rheology: Role of shear-rate number in transition regime

    USGS Publications Warehouse

    Chen, C.-L.; Ling, C.-H.

    1996-01-01

    This paper examines the rationale behind the semiempirical formulation of a generalized viscoplastic fluid (GVF) model in the light of the Reiner-Rivlin constitutive theory and the viscoplastic theory, thereby identifying the parameters that control the rheology of granular flow. The shear-rate number (N) proves to be among the most significant parameters identified from the GVF model. As N ??? 0 and N ??? ???, the GVF model can reduce asymptotically to the theoretical stress versus shear-rate relations in the macroviscous and graininertia regimes, respectively, where the grain concentration (C) also plays a major role in the rheology of granular flow. Using available data obtained from the rotating-cylinder experiments of neutrally buoyant solid spheres dispersing in an interstitial fluid, the shear stress for granular flow in transition between the two regimes proves dependent on N and C in addition to some material constants, such as the coefficient of restitution. The insufficiency of data on rotating-cylinder experiments cannot presently allow the GVF model to predict how a granular flow may behave in the entire range of N; however, the analyzed data provide an insight on the interrelation among the relevant dimensionless parameters.

  7. Vorticity layers in unbounded viscous flow with uniform rates of strain

    NASA Astrophysics Data System (ADS)

    Beronov, K. N.

    1997-10-01

    The Burgers vortex layer solution to the Navier-Stokes equations represents a stationary shear layer driven by a two-dimensional stagnation flow. Here it is generalized to a family of exact solutions representing stationary vorticity layers at stagnation flows with two negative strain rates. As with the Burgers layer, there are corresponding self-similar, time-dependent layer profiles. The layer solutions model the dissipative-scale vorticity structures at early times of flow evolution, when diffuse vorticity is concentrated in layers and simultaneously enhanced and aligned by the stretching of large-scale flows. The new solutions have two generic two-dimensional instabilities: The usual high-Reynolds number causes roll-up. Another instability emerges in the streamwise long-wave limit and makes the Gaussian vorticity layer the fastest-growing mode for any ratio of the negative strain rates. Mathematical arguments are given, suggesting that linear two-dimensional disturbances which are far from these limits, are eventually damped by viscosity.

  8. Inner retinal metabolic rate of oxygen by oxygen tension and blood flow imaging in rat

    PubMed Central

    Wanek, Justin; Teng, Pang-yu; Albers, John; Blair, Norman P.; Shahidi, Mahnaz

    2011-01-01

    Abstract The metabolic function of inner retinal cells relies on the availability of nutrients and oxygen that are supplied by the retinal circulation. Assessment of retinal tissue vitality and function requires knowledge of both the rate of oxygen delivery and consumption. The purpose of the current study is to report a novel technique for assessment of the inner retinal metabolic rate of oxygen (MO2) by combined measurements of retinal blood flow and vascular oxygen tension (PO2) in rat. The application of this technology has the potential to broaden knowledge of retinal oxygen dynamics and advance understanding of disease pathophysiology. PMID:21991548

  9. Association among salivary flow rate, caries risk and nutritional status in pre-schoolers.

    PubMed

    Rodríguez, Patricia N; Martínez Reinoso, Josefina; Gamba, Carlota A; Salgado, Pablo A; Mateo, María Teresa; Manto, María del Carmen; Molgatini, Susana L; Iglesias, Verónica; Argentieri, Ángela B

    2015-01-01

    Modeer T. et al.(2011) claim that there is association between decreased salivary flow rate and caries in obese adolescents. The aim of this study was to determine the association among nutritional status, salivary flow rate and caries risk in preschoolers. The study comprised 60 children aged 3 to 6 years attending kindergartens in areas immediately adjacent to Buenos Aires City, Argentina. Body weight and height of the children were determined. Body mass index was calculated and the population was classified anthropometrically according to the WHO 2007 (WHO Anthro. Program). Caries risk was determined. Saliva was collected in sterile graduated widemouth containers, without stimulation and without food restrictions. Salivary flow rate (SFR) was determined. Statistical analysis was performed using Pearson's test. It was found that 56.7% (IC95%: 37.7-74.0) of anthropometrically adequate children (Ad) and 37.0% (IC95%: 20.1-57.5) of overweight and obese children (OW/Ob) had caries. The odds ratio for caries (OR=3.78; IC95%: 1.2-11.8, p=0.02) was almost 4 times higher in adequate children than in the others. SFR was 0.534 0.318 ml/min in Ad and 0.439 } 0.234 ml/min in OW/Ob. Pearson's test showed no correlation between SFR and nutritional status (r= 0.004592, p= 0.5977). Although the presence of caries was lower in overweight and obese children, no correlation was found between nutritional status and salivary flow rate. PMID:26355891

  10. Development and evaluation of a meter for measuring return line fluid flow rates during drilling

    SciTech Connect

    Loeppke, G.E.; Schafer, D.M.; Glowka, D.A.; Scott, D.D.; Wernig, M.D. ); Wright, E.K. )

    1992-06-01

    The most costly problem routinely encountered in geothermal drilling is lost circulation, which occurs when drilling fluid is lost to the formation rather than circulating back to the surface. The successful and economical treatment of lost circulation requires the accurate measurement of drilling fluid flow rate both into and out of the well. This report documents the development of a meter for measuring drilling fluid outflow rates in the return line of a drilling rig. The meter employs a rolling counterbalanced float that rides on the surface of the fluid in the return line. The angle of the float pivot arm is sensed with a pendulum potentiometer, and the height of the float is calculated from this measurement. The float height is closely related to the fluid height and, therefore, the flow rate in the line. The prototype rolling float meter was extensively tested under laboratory conditions in the Wellbore Hydraulics Flow Facility; results from these tests were used in the design of the field prototype rolling float meter. The field prototype meter was tested under actual drilling conditions in August and September 1991 at the Long Valley Exploratory Well near Mammoth Lakes, Ca. In addition, the performance of several other commercially available inflow and outflow meters was evaluated in the field. The tested inflow meters included conventional pump stroke counters, rotary pump speed counters, magnetic flowmeters, and an ultrasonic Doppler flowmeter. On the return flow line, a standard paddlemeter, an acoustic level meter, and the prototype rolling float meter were evaluated for measuring drilling fluid outflow rates.

  11. Relationship between crash rate and hourly traffic flow on interurban motorways.

    PubMed

    Martin, Jean-Louis

    2002-09-01

    This paper describes the relationship between crash incidence rates and hourly traffic volume and discusses the influence of traffic on crash severity, based on observations made on 2000 km of French interurban motorways over 2 years. Incidence rates involving property damage-only crashes and injury-crashes are highest when traffic is lightest (under 400 vehicles/h). These incidence rates are at their lowest when traffic flows at a rate of 1000-1500 vehicles/h. For heavier traffic flows, crash incidence rates increase steadily as traffic increases on 2- and 3-lane motorways and inflect on 2-lane motorways when traffic increases to a level of 3000 vehicles/h. For an equivalent light traffic level, the number of crashes is higher on three-lane than on 2-lane motorways and higher at weekends (when truck traffic is restricted) than on weekdays. In heavy traffic, the number of crashes is higher on weekdays. We found no significant difference between the number of daytime and night-time crashes, whatever the traffic. No difference was observed in crash severity by number of lanes or period in the week for a given level of traffic. However, severity is greater at night and when hourly traffic is light. Compared to the number of vehicles on the road, light traffic is a safety problem in terms of frequency and severity, and road safety campaigns targeting motorway users to influence their behavior in these driving conditions should be introduced. PMID:12214956

  12. Removal Rates of Aqueous Cr(VI) by Zero-Valent Iron Measured Under Flow Conditions

    SciTech Connect

    Kaplan, D.I.

    2002-05-10

    Studies were undertaken to measure the rate of Cr(VI) removal from the aqueous phase by zero-valent iron, Fe(0), under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a groundwater remediation technology that replaces the sand in a filter pack of a conventional well with a reactive material, such as Fe(0). The pseudo-first-order rate coefficients measured under flow conditions were comparable to those previously measured under batch conditions that had significantly greater ratios of solution volume to Fe(0) surface area. Between the range of 20 and 100 weight percent Fe(0), there was little measurable change in the reaction kinetics. Thus, it may be possible to include sand into the reactive filter packs in the event it is necessary to increase filter pack porosity or to decrease the accumulation of secondary reaction products that may lead to filter pack plugging. Background water chemistry had only marginal effects on reaction rate coefficients. The reaction rates measured in this study indicated that an Fe(0) filter pack could be used to lower Cr(VI) concentrations by several orders of magnitude in a once-through mode of operation of the Reactive Well Technology.

  13. Flow Rate In Microfluidic Pumps As A Function Of Tension and Pump Motor Head Speed

    NASA Astrophysics Data System (ADS)

    Irwin, Anthony; McBride, Krista

    2015-03-01

    As the use of microfluidic devices has become more common in recent years the need for standardization within the pump systems has grown. The pumps are ball bearing rotor microfluidic pumps and work off the idea of peristalsis. The rapid contraction and relaxation propagating down a tube or a microfluidic channel. The ball bearings compress the tube (occlusion) and move along part of the tube length forcing fluid to move inside of the tube in the same direction of the ball bearings. When the ball bearing rolls off the area occupied by the microfluidic channel, its walls and ceiling undergo restitution and a pocket of low pressure is briefly formed pulling more of the liquid into the pump system. Before looking to standardize the pump systems it must be known how the tension placed by the pumps bearing heads onto the PDMS inserts channels affect the pumps performance (mainly the flow rate produced). The relationship of the speed at which the bearings on the motor head spin and the flow rate must also be established. This research produced calibration curves for flow rate vs. tension and rpm. These calibration curves allow the devices to be set to optimal user settings by simply varying either the motor head tension or the motor head speed. I would like to acknowledge the help and support of Vanderbilt University SyBBURE program, Christina Marasco, Stacy Sherod, Franck Block and Krista McBride.

  14. Numerical simulation of hypersonic inlet flows with equilibrium or finite rate chemistry

    NASA Technical Reports Server (NTRS)

    Yu, Sheng-Tao; Hsieh, Kwang-Chung; Shuen, Jian-Shun; Mcbride, Bonnie J.

    1988-01-01

    An efficient numerical program incorporated with comprehensive high temperature gas property models has been developed to simulate hypersonic inlet flows. The computer program employs an implicit lower-upper time marching scheme to solve the two-dimensional Navier-Stokes equations with variable thermodynamic and transport properties. Both finite-rate and local-equilibrium approaches are adopted in the chemical reaction model for dissociation and ionization of the inlet air. In the finite rate approach, eleven species equations coupled with fluid dynamic equations are solved simultaneously. In the local-equilibrium approach, instead of solving species equations, an efficient chemical equilibrium package has been developed and incorporated into the flow code to obtain chemical compositions directly. Gas properties for the reaction products species are calculated by methods of statistical mechanics and fit to a polynomial form for C(p). In the present study, since the chemical reaction time is comparable to the flow residence time, the local-equilibrium model underpredicts the temperature in the shock layer. Significant differences of predicted chemical compositions in shock layer between finite rate and local-equilibrium approaches have been observed.

  15. The role of silane gas flow rate on PECVD-assisted fabrication of silicon nanowires

    NASA Astrophysics Data System (ADS)

    Hamidinezhad, Habib; Ashkarran, Ali Akbar; Abdul-Malek, Zulkurnain

    2016-03-01

    Silicon (Si) core-shell nanowires (NWs) were successfully prepared by very high frequency plasma-enhanced chemical vapor deposition technique, and the effect of silane (SiH4) gas flow rates on physicochemical properties of silicon NWs was investigated. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize SiNWs. Structural properties and morphology of NWs were studied as a function of SiH4 gas flow rate. Microscopic analysis revealed the formation of SiNWs with average tip and stem diameters ranging from 18 to 30 and 21 to 67 nm, respectively. Furthermore, the average length of Si NWs calculated based on the FESEM images was about 300-1800 nm. We have found that the growth of SiNWs increased with increasing in SiH4 gas flow rate. XRD, Raman spectra in addition to high-resolution TEM, verified the formation of crystalline SiNWs. A possible growth mechanism was suggested based on our observations.

  16. Study on three-dimensional printing using electrohydrodynamic inkjet by analysis of mass flow rate

    NASA Astrophysics Data System (ADS)

    Ko, Han Seo; Lee, Soo-Hong; Lee, Pil-Ho; Lee, Sang Won

    2014-11-01

    An electrohydrodynamic (EHD) jet can produce much smaller droplets than nozzle sizes even for highly viscous liquid. Micro scale patterns are produced by a direct patterning of the EHD inkjet printing technique to obtain lamination layers. A cone-jet mode shows good performance for line and surface printings. A prediction method for a flow rate was proposed by performing experiments and deriving an equation. The calculation was carried out by dividing the electric field and the fluid regions. Dielectric liquids were used as the working fluid, whose flow rate was measured at the applied voltage of 1.5 kV to 2.5 kV. The measured flow rate was affected by viscosity, surface tension, and density as fluid properties, and dielectric constant and electric conductivity as properties of electric fields for the voltage. Then, parameters of the printing were investigated by printed line width and thickness at various conditions. As a result, the applied static pressure had more effect on the line printing although the line width was affected by the stage velocity. The significant role of the parameters was confirmed to produce scaffolds using the three-dimensional EHD printing. This work supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Korean government (MEST) (No. S-2011-0023457).

  17. Structural modulation of silicon nanowires by combining a high gas flow rate with metal catalysts

    NASA Astrophysics Data System (ADS)

    Seo, Dongjea; Lee, Jaejun; Kim, Sung Wook; Kim, Ilsoo; Na, Jukwan; Hong, Min-Ho; Choi, Heon-Jin

    2015-04-01

    We grew silicon nanowires (SiNWs) by a vapor-liquid-solid (VLS) mechanism using metal catalysts of gold (Au), titanium (Ti), manganese (Mn), and iron (Fe) under a high flow rate of hydrogen (H2). This combination of catalyst types and high gas flow rate revealed the potential for growing various SiNWs, including kinked SiNWs (with Au), ultra-thin SiNWs having diameters about 5 nm (with Ti), rough-surfaced SiNWs (with Mn), and ribbon-shaped SiNWs tens of microns in width (with Fe). The high flow rate of gas affects the VLS mechanism differently for each combination; for example, it induces an unstable solid-liquid interfaces (with Au), active etching of the catalyst (with Ti), sidewall deposition by a vapor-solid (VS) mechanism, and an asymmetric precipitation of Si in the catalyst (with Fe). Our combinatorial approach may provide a new path for the structural modulation of SiNWs via the VLS mechanism.

  18. Measurements of Flow Rate and Trajectory of Aircraft Tire-Generated Water Spray

    NASA Technical Reports Server (NTRS)

    Daugherty, Robert H.; Stubbs, Sandy M.

    1987-01-01

    An experimental investigation was conducted at the NASA Langley Research Center to measure the flow rate and trajectory of water spray generated by an aircraft tire operating on a flooded runway. Tests were conducted in the Hydrodynamics Research Facility and made use of a partial airframe and a nose tire from a general aviation aircraft. Nose tires from a commercial transport aircraft were also used. The effects of forward speed, tire load, and water depth on water spray patterns were evaluated by measuring the amount and location of water captured by an array of tubes mounted behind the test tire. Water ejected from the side of the tire footprint had the most significant potential for ingestion into engine inlets. A lateral wake created on the water surface by the rolling tire can dominate the shape of the spray pattern as the distance aft of the tire is increased. Forward speed increased flow rates and moved the spray pattern inboard. Increased tire load caused the spray to become less dense. Near the tire, increased water depths caused flow rates to increase. Tests using a fuselage and partial wing along with the nose gear showed that for certain configurations, wing aerodynamics can cause a concentration of spray above the wing.

  19. Water cut measurement of oil-water flow in vertical well by combining total flow rate and the response of a conductance probe

    NASA Astrophysics Data System (ADS)

    Chen, Jianjun; Xu, Lijun; Cao, Zhang; Zhang, Wen; Liu, Xingbin; Hu, Jinhai

    2015-09-01

    In this paper, a conductance probe-based well logging instrument was developed and the total flow rate is combined with the response of the conductance probe to estimate the water cut of the oil-water flow in a vertical well. The conductance probe records the time-varying electrical characteristics of the oil-water flow. Linear least squares regression (LSR) and nonlinear support vector regression (SVR) were used to establish models to map the total flow rate and features extracted from the probe response onto the water cut, respectively. Principal component analysis (PCA) and partial least squares analysis (PLSA) techniques were employed to reduce data redundancy within the extracted features. An experiment was carried out in a vertical pipe with an inner diameter of 125 mm and a height of 24 m in an experimental multi-phase flow setup, Daqing Oilfield, China. In the experiment, oil-water flow was used and the total flow rate varied from 10 to 200 m3 per day and the water cut varied from 0% to 100%. As a direct comparison, the cases were also studied when the total flow rate was not used as an independent input to the models. The results obtained demonstrate that: (1) the addition of the total flow rate as an input to the regression models can greatly improve the accuracy of water cut prediction, (2) the nonlinear SVR model performs much better than the linear LSR model, and (3) for the SVR model with the total flow rate as an input, the adoption of PCA or PLSA not only decreases the dimensions of inputs, but also increases prediction accuracy. The SVR model with five PCA-treated features plus the total flow rate achieves the best performance in water cut prediction, with a coefficient of determination (R2) as high as 0.9970. The corresponding root mean squared error (RMSE) and mean quoted error (MQE) are 0.0312% and 1.99%, respectively.

  20. Effects of Nanodiamond Abrasive Friability in Experimental MR Fluids with Phosphate Laser Glass LHG-8 and Other Optical Glasses

    SciTech Connect

    DeGroote, J.E.; Marino, A.E.; Wilson, J.P.; Spencer, K.E.; Jacobs, S.D.

    2005-09-22

    Research is currently being conducted to better understand the role that nanodiamond abrasives play in the removal process of Magnetorheological Finishing (MRF). The following presents removal rate data for a set of six optical glasses that were spotted (not polished out) with four different MR fluids, as well as texturing/smoothing data for phosphate laser glass LHG-8.

  1. Heart rate in the pathophysiology of coronary blood flow and myocardial ischaemia: benefit from selective bradycardic agents

    PubMed Central

    Heusch, G

    2008-01-01

    Starting out from a brief description of the determinants of coronary blood flow (perfusion, pressure, extravascular compression, autoregulation, metabolic regulation, endothelium-mediated regulation and neurohumoral regulation) the present review highlights the overwhelming importance of metabolic regulation such that coronary blood flow is increased at increased heart rate under physiological circumstances and the overwhelming importance of extravascular compression such that coronary blood flow is decreased at increased heart rate through reduction of diastolic duration in the presence of severe coronary stenoses. The review goes on to characterize the role of heart rate in the redistribution of regional myocardial blood flow between a normal coronary vascular tree with preserved autoregulation and a poststenotic vasculature with exhausted coronary reserve. When flow is normalized by heart rate, there is a consistent close relationship of regional myocardial blood flow and contractile function for each single cardiac cycle no matter whether or not there is a coronary stenosis and what the actual blood flow is. β-Blockade improves both flow and function along this relationship. When the heart rate reduction associated with β-blockade is prevented by pacing, α-adrenergic coronary vasoconstriction is unmasked and both flow and function are deteriorated. Selective heart rate reduction, however, improves both flow and function without any residual negative effect such as unmasked α-adrenergic coronary vasoconstriction or negative inotropic action. PMID:18223669

  2. Improved wound healing in blue LED treated superficial abrasions

    NASA Astrophysics Data System (ADS)

    Rossi, Francesca; Tatini, Francesca; Pini, Roberto; Bacci, Stefano; De Siena, Gaetano; Cicchi, Riccardo; Pavone, Francesco; Alfieri, Domenico

    2013-06-01

    A blue-LED photocoagulator device was designed in order to induce a selective photocoagulation effect in superficial bleeding. An in vivo study in rat back skin evidenced an improved healing process in the LED treated abrasions.

  3. Dermoscopy and Onychomycosis: guided nail abrasion for mycological samples*

    PubMed Central

    Bet, Diego Leonardo; dos Reis, Ana Lucia; Chiacchio, Nilton Di; Belda Junior, Walter

    2015-01-01

    Mycological examination is still the cornerstone for the diagnosis of onychomycosis for many dermatologists, but sampling technique interferes on its sensitivity and specificity. Nail abrasion may be used to reach the most proximal part of the lesion and can be easily accomplished with an electric abrasor. We suggest nail plate dermoscopy to identify the best location for localized abrasion to obtain adequate samples for mycological examination. PMID:26734877

  4. Dermoscopy and Onychomycosis: guided nail abrasion for mycological samples.

    PubMed

    Bet, Diego Leonardo; Reis, Ana Lucia dos; Di Chiacchio, Nilton; Belda Junior, Walter

    2015-01-01

    Mycological examination is still the cornerstone for the diagnosis of onychomycosis for many dermatologists, but sampling technique interferes on its sensitivity and specificity. Nail abrasion may be used to reach the most proximal part of the lesion and can be easily accomplished with an electric abrasor. We suggest nail plate dermoscopy to identify the best location for localized abrasion to obtain adequate samples for mycological examination. PMID:26734877

  5. Dentifrice fluoride and abrasivity interplay on artificial caries lesions.

    PubMed

    Nassar, Hani M; Lippert, Frank; Eckert, George J; Hara, Anderson T

    2014-01-01

    Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 mM) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey's tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and abrasivity directly impacted SL and mineral gain of enamel caries lesions. PMID:24993884

  6. Computed tomography to quantify tooth abrasion

    NASA Astrophysics Data System (ADS)

    Kofmehl, Lukas; Schulz, Georg; Deyhle, Hans; Filippi, Andreas; Hotz, Gerhard; Berndt-Dagassan, Dorothea; Kramis, Simon; Beckmann, Felix; Müller, Bert

    2010-09-01

    Cone-beam computed tomography, also termed digital volume tomography, has become a standard technique in dentistry, allowing for fast 3D jaw imaging including denture at moderate spatial resolution. More detailed X-ray images of restricted volumes for post-mortem studies in dental anthropology are obtained by means of micro computed tomography. The present study evaluates the impact of the pipe smoking wear on teeth morphology comparing the abraded tooth with its contra-lateral counterpart. A set of 60 teeth, loose or anchored in the jaw, from 12 dentitions have been analyzed. After the two contra-lateral teeth were scanned, one dataset has been mirrored before the two datasets were registered using affine and rigid registration algorithms. Rigid registration provides three translational and three rotational parameters to maximize the overlap of two rigid bodies. For the affine registration, three scaling factors are incorporated. Within the present investigation, affine and rigid registrations yield comparable values. The restriction to the six parameters of the rigid registration is not a limitation. The differences in size and shape between the tooth and its contra-lateral counterpart generally exhibit only a few percent in the non-abraded volume, validating that the contralateral tooth is a reasonable approximation to quantify, for example, the volume loss as the result of long-term clay pipe smoking. Therefore, this approach allows quantifying the impact of the pipe abrasion on the internal tooth morphology including root canal, dentin, and enamel volumes.

  7. Development of intermetallic-hardened abrasion-resistant weld hardfacing alloys

    SciTech Connect

    School, M.R.

    1986-01-01

    Chromium and cobalt are strategic materials in the US and both are major constituents in many weld hardfacing alloys. Substitution for these materials or alternatives to their use was a primary direction of this investigation which was conducted in conjunction with the US Bureau of Mines. Minimization of the use of strategic materials was the criteria guiding the development of intermetallic-hardened abrasion resistant weld hardfacing materials. Other criteria were that the new alloy contain a hard intermetallic compound in an FCC matrix, and that these intermetallic compounds be stable at room temperature. A survey of ternary systems was made and the Fe-Mo-Ni system was selected to provide a basis for alloy development. Fe-Mo-Ni alloys synthesized by arc-melting and similar alloys made by welding possessed similar microstructures, a (Fe, Ni){sub 7}Mo{sub 6} intermetallic plus austenite eutectic in an austenitic matrix. These materials exhibited poor abrasive resistance. Silicon additions to the alloy promoted formation of a Laves phase FeMoSi intermetallic which helped increase the abrasive wear resistance. Through a series of alloy chemistry iterations a final composition of Fe-20Mo-15Ni-5Si was selected. Heat treatment of this alloy at 550 to 650 C caused second phase precipitation in the matrix and raised the hardness about 14 points HRC to 50 HRC. The alloy's wear rate, measured with the pin-on-drum abrasive wear test, was 6.3 to 6.5 mg/m. However this was twice the wear rate observed in commercial high-carbon high-chromium alloys. Based on examination of the alloy microstructures, their chemistry, and an analysis of the Fe-Mo-Si phase system; directions for further research are to increase the molybdenum and silicon content to produce a Fe-20Mo-10Ni-15Si composition.

  8. ZERO-VALENT IRON REMOVAL RATES OF AQUEOUS Cr(VI) MEASURED UNDER FLOW CONDITIONS

    SciTech Connect

    Kaplan, Daniel I.; Gilmore, Tyler J.

    2004-06-01

    The rates of Cr(VI) removal from the aqueous phase by zero-valent iron, Fe(0), was measured under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a groundwater remediation technology that replaces the sand in a filter pack of a conventional well with a reactive material, such as Fe(0). Dissolved Cr(VI) concentration, dissolved O2 concentration, and Eh data indicated that Cr(VI) removal from the aqueous phase was mass-transfer limited. All pseudo-first-order regression fits to the data were significant (P≤0.05), however, they did not capture many of the salient aspects of the data, including that the removal rate often decreased as contact time increased. As such, application of these rate coefficients to predict long-term Cr(VI) removal were compromised. The rate coefficients measured under flow conditions were comparable to those measured previously under batch conditions with significantly greater solution:solid ratios. Between the range of 20 and 100 wt-% Fe(0) in the column, there was little measurable change in the reaction kinetics. Thus, it may be possible to include sand into the reactive filter packs in the event it is necessary to increase filter pack porosity or to decrease the accumulation of secondary reaction products that may lead to filter pack plugging. Background water chemistry (0.2 M NaHCO3, distilled water, and a carbonate-dominated groundwater) had only marginal, if any, effects on reaction rate coefficients. The reaction rates measured in this study indicated that an Fe(0) filter pack could be used to lower Cr(VI) concentrations by several orders of magnitude in a once-through mode of operation of the Reactive Well Technology.

  9. Method of protecting surfaces from abrasion and abrasion resistant articles of manufacture

    DOEpatents

    Hirschfeld, T.B.

    1988-06-09

    Surfaces of fabricated structures are protected from damage by impacting particulates by a coating of hard material formed as a mass of thin flexible filaments having root ends secured to the surface and free portions which can flex and overlap to form a resilient cushioning mat which resembles hair or fur. The filamentary coating covers the underlying surface with hard abrasion resistance material while also being compliant and capable of local accommodation to particle impacts. The coating can also function as thermal and/or acoustical insulation and has a friction reducing effect. 11 figs.

  10. Influence of paleo-heat flow variations on estimates of exhumation rates

    NASA Astrophysics Data System (ADS)

    von Hagke, Christoph; Luijendijk, Elco

    2016-04-01

    Deriving exhumation estimates from thermochronological data requires assumptions on the paleo-thermal field of the Earth's crust. Existing thermal models take into account heat transfer by diffusion and advection caused by the movement of the crust and erosion as well as changes in geothermal gradient over time caused by changes in structure or thermal properties of the crust, surface temperature and elevation. However, temperature field of mountain belts and basins may vary not only due to tectonic activity or landscape evolution. We present a high-resolution thermochronology data set from the foreland fold-and-thrust belt of the European Alps that shows substantial variation of cooling rates probably caused by hydrothermal flow in the subsurface in the past. Tectonic blocks with uniform exhumation history show variations in cooling of up to 50°C. In addition, changes in cooling between two different fault blocks show opposite trend than expected by models of their tectonic history. The observed historic changes in paleo-geothermal gradients are equal in magnitude to a present-day thermal anomaly caused by the upward flow of warm fluids in the distal part of the foreland basin. The strong variations in geothermal gradients by fluid flow imply that straightforward interpretation of landscape evolution rates using thermochronology is not possible, unless the thermal effects of fluid flow are taken into account. This is of particular importance to studies where the amount of thermochronology data is limited and local hydrothermal anomalies could easily be interpreted as regional exhumation signals. On the other hand, our findings suggest that thermochronology offers new opportunities to constrain magnitude and timing of paleo-heat flow variations in the upper crust.

  11. The effect of a 6 Fr catheter on flow rate in men

    PubMed Central

    Richard, Patrick; Ordonez, Nydia Icaza; Tu, Le Mai

    2013-01-01

    Background: The pressure-flow study (PFS) is considered the gold standard for the detection of bladder outlet obstruction (BOO) in men. However, several studies have raised the possibility that transurethral catheterization might have an obstructive effect on PFS while others did not. Objectives: To evaluate the effect of a 6 Fr transurethral catheter on the pressure-flow study and to evaluate its clinical implication in men. Materials and Methods: A retrospective chart review study of 515 men referred for an evaluation of lower urinary tract symptoms and who underwent an urodynamic study (UDS). Of those, 133 met our inclusion/exclusion criteria. Non invasive free-flow studies (NIFFS) were performed before every UDS. Cystometrogram and PFS were performed through a 6 Fr transurethral catheter. Results: The maximal flow rate (Qmax) was significantly higher (P < 0.001) in the NIFFS (15.0 mL/s (range 9.0-23.0)) than in the PFS (11.0 mL/s (range 7.0-18.5)). This difference became greater (18.5 mL/s (range 10.0-30.3) vs. 13.0 mL/s (range 6.0-25.0), in favor of the NIFFS) when we analyzed only the patients (n = 34) who voided a similar volume. According to the International Continence Society (ICS) nomogram, the use of the PFS alone would have resulted in the upstaging of 14% of cases (10/71) in the overall population and 24% (4/17) in the sub-analyzed group. Conclusion: A 6 Fr transurethral catheter significantly lowers the maximal flow rate by 4 mL/s. Its presence resulted in an upstaging on the ICS nomogram. However, further studies will be necessary to confirm this upstaging. PMID:24311907

  12. 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.

  13. Zonal rate model for stacked membrane chromatography. I: characterizing solute dispersion under flow-through conditions.

    PubMed

    Francis, Patrick; von Lieres, Eric; Haynes, Charles A

    2011-08-01

    Conventional models of both packed-bed and stacked-membrane chromatography typically attribute elution band broadening to non-idealities within the column. However, when the column length to diameter ratio is greatly reduced, as in stacked-membrane chromatography, variations in solute residence times within the feed-distribution (inlet) and eluent-collection (outlet) manifolds can also contribute to band broadening. We report on a new zonal rate model (ZRM) for stacked-membrane chromatography that improves on existing hold-up volume models that rely on one plug-flow reactor and one stirred-tank reactor in series to describe dispersion of solute during transport into and out of the column. The ZRM radially partitions the membrane stack and the hold-up volumes within the inlet and outlet manifolds into zones to better capture non-uniform flow distribution effects associated with the large column diameter to height ratio. Breakthrough curves from a scaled-down anion-exchange membrane chromatography module using ovalbumin as a model protein were collected at flow rates ranging from 1.5 to 20 mL min(-1) under non-binding conditions and used to evaluate the ZRM as well as previous models. The ZRM was shown to be significantly more accurate in describing protein dispersion and breakthrough. The model was then used to decompose breakthrough data, where it was found that variations in solute residence time distributions within the inlet and outlet manifolds make the dominant contribution to solute dispersion over the recommended range of feed flow rates. The ZRM therefore identifies manifold design as a critical contributor to separation quality within stacked-membrane chromatography units. PMID:21703630

  14. Bedform genesis in bedrock substrates: Insights into formative processes from a new experimental approach and the importance of suspension-dominated abrasion

    NASA Astrophysics Data System (ADS)

    Yin, Daowei; Peakall, Jeff; Parsons, Dan; Chen, Zhongyuan; Averill, Heather Macdonald; Wignall, Paul; Best, Jim

    2016-02-01

    Bedrock channels are common in the natural environment, and bedrock channel erosion sets the pace of denudation in many river catchments. However, in comparison to the large number of studies concerning the formation of alluvial bedforms, relatively few investigations have concerned bedrock bedform genesis. Field-based analysis of sculptured forms within bedrock channels has been restricted notably by the slow rate of bedform development in such environments. Furthermore, only a limited number of flume-scale experiments have been conducted that attempt to simulate the genesis of sculpted bedforms in bedrock channels. This study demonstrates that optimisation of clay beds through analysis of clay strength enables the development of features analogous to bedrock river channel bedforms - even at a scale that is orders of magnitude smaller than some natural examples. Three sets of suspended sediment-laden experiments were carried out using hard, medium, and soft clay bed substrates. A suite of erosive bedforms (including potholes, flutes, and furrows) developed on all experimental beds. All observed erosional features have clear equivalents to those observed in natural bedrock rivers. Bed shear strength was found to be a significant factor for the genesis of different types of simulated bedrock bedforms in our experiments with other factors, such as flow velocity, bed slope, and flow depth held approximately constant. Importantly, in a subset of experiments performed with an absence of suspended sediment, fluid flow did not result in the erosion and development of bedforms in the clay bed. Hence, this work illustrates that abrasion by suspended sediments is the key process required for the formation of these simulated bedrock bedforms in our experiments, in the absence of bedload abrasion; other processes such as plucking, cavitation, and dissolution will have been negligible.

  15. Measurement of proton transfer reaction rates in a microwave cavity discharge flowing afterglow

    NASA Astrophysics Data System (ADS)

    Brooke, George M., IV

    The reaction rate coefficients between the hydronium ion and the molecules ethene (C2H4), propene (C 3H6), 1-butene (C4H8) and hydrogen sulfide (H2S) were measured at 296 K. The measured reaction rates were compared to collision rates calculated using average dipole orientation (ADO) theory. Reaction efficiency depends primarily upon the proton affinity of the molecules. All the measurements were obtained using the newly developed microwave cavity discharge flowing afterglow (MCD-FA) apparatus. This device uses an Asmussen-type microwave cavity discharge ion source that is spatially separated from the flow tube, eliminating many of the problems inherent with the original FA devices. In addition to measuring reaction rate coefficients, the MCD-FA was shown to be an effective tool for measuring trace compounds in atmospheric air. This method has many advantages over current detection techniques since compounds can be detected in almost real time, large mass ranges can be scanned quickly, and repeated calibration is not required. Preliminary measurements were made of car exhaust and exhaled alveolar air. Car exhaust showed the presence of numerous hydrocarbons, such as butene, benzene and toluene while the exhaled alveolar air showed the presence of various volatile organic compounds such as methanol and acetone.

  16. Hypothermia reduces cerebral metabolic rate and cerebral blood flow in newborn pigs

    SciTech Connect

    Busija, D.W.; Leffler, C.W. )

    1987-10-01

    The authors examined effects of hypothermia on cerebral metabolic rate and cerebral blood flow in anesthetized, newborn pigs (1-4 days old). Cerebral blood flow (CBF) was determined with 15-{mu}m radioactive microspheres. Regional CBF ranged from 44 to 66 ml{center dot}min{sup {minus}1}{center dot}100 g{sup {minus}1}, and cerebral metabolic rate was 1.94 {plus minus} 0.23 ml O{sub 2}{center dot}100 g{sup {minus}1}{center dot}min{sup {minus}1} during normothermia (39{degree}C). Reduction of rectal temperature to 34-35{degree}C decreased CBF and cerebral metabolic rate 40-50%. In another group of piglets, they examined responsiveness of the cerebral circulation to arterial hypercapnia during hypothermia. Although absolute values for normocapnic and hypercapnic CBF were reduced by hypothermia and absolute values for normocapnic and hypercapnic cerebrovascular resistance were increased, the percentage changes from control in these variables during hypercapnia were similar during normothermia and hypothermia. In another group of animals that were maintained normothermic and exposed to two episodes of hypercapnia, there was no attenuation of cerebrovascular dilation during the second episode. They conclude that hypothermia reduces CBF secondarily to a decrease in cerebral metabolic rate and that percent dilator responsiveness to arterial hypercapnia is unaltered when body temperature is reduced.

  17. Analysis of Abrasive Blasting of DOP-26 Iridium Alloy

    SciTech Connect

    Ohriner, Evan Keith; Zhang, Wei; Ulrich, George B

    2012-01-01

    The effects of abrasive blasting on the surface geometry and microstructure of DOP-26 iridium alloy (Ir-0.3% W-0.006% Th 0.005% Al) have been investigated. Abrasive blasting has been used to control emissivity of components operating at elevated temperature. The effects of abrasive blasting conditions on surface morphology were investigated both experimentally and by numerical modeling. The simplified model, based on finite element analysis of a single angular particle impacting on Ir alloy disk, calculates the surface deformation and residual strain distribution. The experimental results and modeling results both indicate that the surface geometry is not sensitive to the abrasive blast process conditions of nozzle pressure and standoff distance considered in this study. On the other hand, the modeling results suggest that the angularity of the abrasive particle has an important role in determining surface geometry, which in turn, affects the emissivity. Abrasive blasting causes localized surface strains and localized recrystallization, but it does not affect grain size following extended exposure at elevated temperature. The dependence of emissivity of the DOP-26 alloy on mean surface slope follows a similar trend to that reported for pure iridium.

  18. Observation of pressure gradient and related flow rate effect on the plasma parameters in plasma processing reactor

    SciTech Connect

    Lee, Hyo-Chang; Kim, Aram; Chung, Chin-Wook; Moon, Se Youn

    2011-02-15

    In industrial plasma processes, flow rate has been known to a key to control plasma processing results and has been discussed with reactive radical density, gas residence time, and surface reaction. In this study, it was observed that the increase in the flow rate can also change plasma parameters (electron temperature and plasma density) and electron energy distribution function in plasma processing reactor. Based on the measurement of gas pressure between the discharge region and the pumping port region, the considerable differences in the gas pressure between the two regions were found with increasing flow rate. It was also observed that even in the discharge region, the pressure gradient occurs at the high gas flow rate. This result shows that increasing the flow rate results in the pressure gradient and causes the changes in the plasma parameters.

  19. Reynolds-stress and dissipation rate budgets in a turbulent channel flow

    NASA Technical Reports Server (NTRS)

    Mansour, N. N.; Kim, J.; Moin, P.

    1987-01-01

    The budgets for the Reynolds stresses and for the dissipation rate of the turbulence kinetic energy are computed using direct simulation data of a turbulent channel flow. The budget data reveal that all the terms in the budget become important close to the wall. For inhomogeneous pressure boundary conditions, the pressure-strain term is split into a return term, a rapid term, and a Stokes term. The Stokes term is important close to the wall. The rapid and return terms play different roles depending on the component of the term. A split of the velocity pressure-gradient term into a redistributive term and a diffusion term is proposed, which should be simpler to model. The budget data is used to test existing closure models for the pressure-strain term, the dissipation rate, and the transport rate. In general, further work is needed to improve the models.

  20. Aero-optics: Simultaneous MHz Rate Planar Flow Visualization and Optical Wavefront Measurements

    NASA Astrophysics Data System (ADS)

    Thurow, Brian; Samimy, Mo; Lempert, Walter; Harris, Scott; Widiker, Jeff; Duncan, Bradley

    2002-11-01

    In response to a need for more detailed understanding of aero-optic effects in realistic flows (high-speed and compressible), we apply very recently developed MHz rate planar diagnostic techniques to simultaneously perform flow visualization and wavefront measurement on a Mach 1.3 rectangular jet. A custom-built pulse burst laser is used to produce 17 pulses (10 nsec duration) with inter-pulse timing of 4 microseconds (250 kHz). The pulses were formed into a laser sheet and illuminated the mixing layer in a streamwise plane of a Mach 1.3 rectangular, aspect ratio 3 jet. Images were captured using a Dalsa 64K1M camera that can record 17 images at framing rates as high as 1 MHz. Optical wavefronts were measured at rates up to 1 MHz using a newly designed Shack-Hartmann (SH) wavefront sensor. A 10 mW HeNe laser beam was spatially filtered and expanded to a 2.5 cm diameter and passed through the center of the rectangular jet 8 nozzle exit heights downstream of the nozzle exit. A lenslet array (1.024 mm pitch, 260 mm f. l.) and a -1000 mm f. l. lens are used to form a grid pattern of dots onto a PSI-IV camera capable of capturing 28 frames at 1 MHz framing rates. The camera was operated at 500 kHz and imaged a 6 x 6 pattern of dots. The displacement of each dot corresponds to the local wavefront tilt induced by the jet as the initially planar wavefront passes through the flow. Results are being analyzed to obtain a correlation between turbulence structures contained in the mixing layer of the jet and the optical distortion produced by these structures.