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Sample records for radial flow chromatography

  1. Experimental consideration of capillary chromatography based on tube radial distribution of ternary mixture carrier solvents under laminar flow conditions.

    PubMed

    Jinno, Naoya; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

    2011-01-01

    A capillary chromatography system has been developed based on the tube radial distribution of the carrier solvents using an open capillary tube and a water-acetonitrile-ethyl acetate mixture carrier solution. This tube radial distribution chromatography (TRDC) system works under laminar flow conditions. In this study, a phase diagram for the ternary mixture carrier solvents of water, acetonitrile, and ethyl acetate was constructed. The phase diagram that included a boundary curve between homogeneous and heterogeneous solutions was considered together with the component ratios of the solvents in the homogeneous carrier solutions required for the TRDC system. It was found that the TRDC system performed well with homogeneous solutions having component ratios of the solvents that were positioned near the homogeneous-heterogeneous solution boundary of the phase diagram. For preparing the carrier solutions of water-hydrophilic/hydrophobic organic solvents for the TRDC system, we used for the first time methanol, ethanol, 1,4-dioxane, and 1-propanol, instead of acetonitrile (hydrophilic organic solvent), as well as chloroform and 1-butanol, instead of ethyl acetate (hydrophobic organic solvent). The homogeneous ternary mixture carrier solutions were prepared near the homogeneous-heterogeneous solution boundary. Analyte mixtures of 2,6-naphthalenedisulfonic acid and 1-naphthol were separated with the TRDC system using these homogeneous ternary mixture carrier solutions. The pressure change in the capillary tube under laminar flow conditions might alter the carrier solution from homogeneous in the batch vessel to heterogeneous, thus affecting the tube radial distribution of the solvents in the capillary tube. PMID:21415507

  2. Radial flow heat exchanger

    DOEpatents

    Valenzuela, Javier

    2001-01-01

    A radial flow heat exchanger (20) having a plurality of first passages (24) for transporting a first fluid (25) and a plurality of second passages (26) for transporting a second fluid (27). The first and second passages are arranged in stacked, alternating relationship, are separated from one another by relatively thin plates (30) and (32), and surround a central axis (22). The thickness of the first and second passages are selected so that the first and second fluids, respectively, are transported with laminar flow through the passages. To enhance thermal energy transfer between first and second passages, the latter are arranged so each first passage is in thermal communication with an associated second passage along substantially its entire length, and vice versa with respect to the second passages. The heat exchangers may be stacked to achieve a modular heat exchange assembly (300). Certain heat exchangers in the assembly may be designed slightly differently than other heat exchangers to address changes in fluid properties during transport through the heat exchanger, so as to enhance overall thermal effectiveness of the assembly.

  3. Radial flow pulse jet mixer

    DOEpatents

    VanOsdol, John G.

    2013-06-25

    The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing vessel is comprised of a sludge basin, a flow surface surrounding the sludge basin, and a downcoming flow annulus between the flow surface and an inner shroud. The pulse jet mixing vessel is additionally comprised of an upper vessel pressurization volume in fluid communication with the downcoming flow annulus, and an inner shroud surge volume separated from the downcoming flow annulus by the inner shroud. When the solid particles are resting on the sludge basin and a fluid such as water is atop the particles and extending into the downcoming flow annulus and the inner shroud surge volume, mixing occurs by pressurization of the upper vessel pressurization volume, generating an inward radial flow over the flow surface and an upwash jet at the center of the sludge basin.

  4. Stirling Engine With Radial Flow Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Vitale, N.; Yarr, George

    1993-01-01

    Conflict between thermodynamical and structural requirements resolved. In Stirling engine of new cylindrical configuration, regenerator and acceptor and rejector heat exchangers channel flow of working gas in radial direction. Isotherms in regenerator ideally concentric cylinders, and gradient of temperature across regenerator radial rather than axial. Acceptor and rejector heat exchangers located radially inward and outward of regenerator, respectively. Enables substantial increase in power of engine without corresponding increase in diameter of pressure vessel.

  5. Radial flow nuclear thermal rocket (RFNTR)

    DOEpatents

    Leyse, Carl F.

    1995-01-01

    A radial flow nuclear thermal rocket fuel assembly includes a substantially conical fuel element having an inlet side and an outlet side. An annular channel is disposed in the element for receiving a nuclear propellant, and a second, conical, channel is disposed in the element for discharging the propellant. The first channel is located radially outward from the second channel, and separated from the second channel by an annular fuel bed volume. This fuel bed volume can include a packed bed of loose fuel beads confined by a cold porous inlet frit and a hot porous exit frit. The loose fuel beads include ZrC coated ZrC-UC beads. In this manner, nuclear propellant enters the fuel assembly axially into the first channel at the inlet side of the element, flows axially across the fuel bed volume, and is discharged from the assembly by flowing radially outward from the second channel at the outlet side of the element.

  6. Radial flow nuclear thermal rocket (RFNTR)

    DOEpatents

    Leyse, Carl F.

    1995-11-07

    A radial flow nuclear thermal rocket fuel assembly includes a substantially conical fuel element having an inlet side and an outlet side. An annular channel is disposed in the element for receiving a nuclear propellant, and a second, conical, channel is disposed in the element for discharging the propellant. The first channel is located radially outward from the second channel, and separated from the second channel by an annular fuel bed volume. This fuel bed volume can include a packed bed of loose fuel beads confined by a cold porous inlet frit and a hot porous exit frit. The loose fuel beads include ZrC coated ZrC-UC beads. In this manner, nuclear propellant enters the fuel assembly axially into the first channel at the inlet side of the element, flows axially across the fuel bed volume, and is discharged from the assembly by flowing radially outward from the second channel at the outlet side of the element.

  7. Fast radial flows in transition disk holes

    SciTech Connect

    Rosenfeld, Katherine A.; Andrews, Sean M.; Chiang, Eugene

    2014-02-20

    Protoplanetary 'transition' disks have large, mass-depleted central cavities, yet also deliver gas onto their host stars at rates comparable to disks without holes. The paradox of simultaneous transparency and accretion can be explained if gas flows inward at much higher radial speeds inside the cavity than outside the cavity, since surface density (and by extension optical depth) varies inversely with inflow velocity at fixed accretion rate. Radial speeds within the cavity might even have to approach free-fall values to explain the huge surface density contrasts inferred for transition disks. We identify observational diagnostics of fast radial inflow in channel maps made in optically thick spectral lines. Signatures include (1) twisted isophotes in maps made at low systemic velocities and (2) rotation of structures observed between maps made in high-velocity line wings. As a test case, we apply our new diagnostic tools to archival Atacama Large Millimeter Array data on the transition disk HD 142527 and uncover evidence for free-fall radial velocities inside its cavity. Although the observed kinematics are also consistent with a disk warp, the radial inflow scenario is preferred because it predicts low surface densities that appear consistent with recent observations of optically thin CO isotopologues in this disk. How material in the disk cavity sheds its angular momentum wholesale to fall freely onto the star is an unsolved problem; gravitational torques exerted by giant planets or brown dwarfs are briefly discussed as a candidate mechanism.

  8. Radial slot flows in solid rocket motors

    NASA Astrophysics Data System (ADS)

    Hilbing, J. H.; Heister, S. D.

    1993-06-01

    A series of parametric numerical solutions have been generated to characterize the two-dimensional flowfield due to the presence of a radial slot in a solid rocket propellant grain. Results have been parameterized in terms of upstream core Mach number, slot contraction ratio, and slot-to-core mass flow and momentum ratios. Numerical solutions of the axisymmetric Euler equations have been obtained on a 'generic' slot geometry using a cell-centered, finite volume scheme. Results indicate that both the stagnation pressure loss and grain suction force on the propellant segment downstream of the slot correlate well with slot-to-core momentum ratio; a parameter which has not been used in previous studies. Significant differences (in stagnation pressure losses) have been identified between the 2-D numerical results and the 1-D methods applied in current state-of-the-art ballistics codes. We anticipate that the correlations derived through this parametric study can be used in preliminary performance and grain stress analyses performed during the motor development process.

  9. Radial Chromatography for the Separation of Nitroaniline Isomers

    ERIC Educational Resources Information Center

    Miller, Robert B.; Case, William S.

    2011-01-01

    Separation techniques are usually presented in the undergraduate organic laboratory to teach students how to purify and isolate compounds. Often the concept of liquid chromatography is introduced by having students create "silica gel columns" to separate components of a reaction mixture. Although useful, column chromatography can be a laborious…

  10. Low cost, radial flow, solid oxide fuel cell

    SciTech Connect

    Petrik, M.A.

    1993-11-01

    The Interscience Radial Flow (IRF) SOFC is designed to minimize problems in high-temperature operation, and for low-cost fabrication. The cell has planar, non-sintered construction, uses particulate materials to form porous electrodes, and has internal radial flow. This phase was to demonstrate feasibility of multi-cell stack operation. Performance milestone was 15% DC HHV efficiency with hydrogen at > 50 mW/cm{sup 2} over 100 h.

  11. Radial flow afterburner for event generators and the baryon puzzle

    NASA Astrophysics Data System (ADS)

    Cuautle, E.; Paic, G.

    2008-07-01

    A simple afterburner to add radial flow to the randomized transverse momentum obtained from event generators, PYTHIA and HIJING, has been implemented to calculate the p/π ratios and compare them with available data. A coherent trend of qualitative agreement has been obtained in pp and Au+Au collisions for various centralities. These results indicate that the radial flow does play an important role in the so-called baryon puzzle anomaly.

  12. Dynamics of a vortex pair in radial flow

    SciTech Connect

    Bannikova, E. Yu. Kontorovich, V. M. Reznik, G. M.

    2007-10-15

    The problem of vortex pair motion in two-dimensional radial flow is solved. Under certain conditions for flow parameters, the vortex pair can reverse its motion within a bounded region. The vortex-pair translational velocity decreases or increases after passing through the source/sink region, depending on whether the flow is diverging or converging, respectively. The rotational motion of a corotating vortex pair in a quiescent environment transforms into motion along a logarithmic spiral in radial flow. The problem may have applications in astrophysics and geophysics.

  13. Sugar Determination in Foods with a Radially Compressed High Performance Liquid Chromatography Column.

    ERIC Educational Resources Information Center

    Ondrus, Martin G.; And Others

    1983-01-01

    Advocates use of Waters Associates Radial Compression Separation System for high performance liquid chromatography. Discusses instrumentation and reagents, outlining procedure for analyzing various foods and discussing typical student data. Points out potential problems due to impurities and pump seal life. Suggests use of ribose as internal…

  14. Effect of the radial buoyancy on a circular Couette flow

    NASA Astrophysics Data System (ADS)

    Meyer, Antoine; Yoshikawa, Harunori N.; Mutabazi, Innocent

    2015-11-01

    The effect of a radial temperature gradient on the stability of a circular Couette flow is investigated when the gravitational acceleration is neglected. The induced radial stratification of the fluid density coupled with the centrifugal acceleration generates radial buoyancy which is centrifugal for inward heating and centripetal for outward heating. This radial buoyancy modifies the Rayleigh discriminant and induces the asymmetry between inward heating and outward heating in flow behavior. The critical modes are axisymmetric and stationary for inward heating while for outward heating, they can be oscillatory axisymmetric or nonaxisymmetric depending on fluid diffusion properties, i.e., on the Prandtl number Pr. The dependence of the critical modes on Pr is explored for different values of the radius ratio of the annulus. The power input of the radial buoyancy is compared with other power terms. The critical frequency of the oscillatory axisymmetric modes is linked to the Brunt-Väisälä frequency due to the density stratification in the radial gravity field induced by the rotation. These modes are associated with inertial waves. The dispersion relation of the oscillatory axisymmetric modes is derived in the vicinity of the critical conditions. A weakly nonlinear amplitude equation with a forcing term is proposed to explain the domination of these axisymmetric oscillatory modes over the stationary centrifugal mode.

  15. Self-sustained radial oscillating flows between parallel disks

    NASA Astrophysics Data System (ADS)

    Mochizuki, S.; Yang, W.-J.

    1985-05-01

    It is pointed out that radial flow between parallel circular disks is of interest in a number of physical systems such as hydrostatic air bearings, radial diffusers, and VTOL aircraft with centrally located downward-positioned jets. The present investigation is concerned with the problem of instability in radial flow between parallel disks. A time-dependent numerical study and experiments are conducted. Both approaches reveal the nucleation, growth, migration, and decay of annular separation bubbles (i.e. vortex or recirculation zones) in the laminar-flow region. A finite-difference technique is utilized to solve the full unsteady vorticity transport equation in the theoretical procedure, while the flow patterns in the experiments are visualized with the aid of dye-injection, hydrogen-bubble, and paraffin-mist methods. It is found that the separation and reattachment of shear layers in the radial flow through parallel disks are unsteady phenomena. The sequence of nucleation, growth, migration, and decay of the vortices is self-sustained.

  16. Longitudinal Dispersivity in a Radial Diverging Flow Field

    NASA Astrophysics Data System (ADS)

    Seaman, J. C.; Wilson, M.; Bertsch, P. M.; Aburime, S. A.

    2005-12-01

    Hydrodynamic dispersion is an important factor controlling contaminant migration in the subsurface environment. However, few comprehensive data sets exist for evaluating the impact of travel distance and site heterogeneity on solute dispersion under non-uniform flow conditions. In addition, anionic tracers are often used to estimate physical transport parameters based on an erroneous assumption of conservative (i.e., non-reactive) behavior. Therefore, a series of field experiments using tritiated water and several other commonly used hydrologic tracers (Br, Cl, FBAs) were conducted in the water-table aquifer on the U.S. Department of Energy's Savannah River Site (Aiken, SC) to evaluate solute transport processes in a diverging radial flow field. For each experiment, tracer-free groundwater was injected for approximately 24 hours at a fixed rate of 56.7 L/min (15 gpm) to establish a forced radial gradient prior to the introduction of a tracer pulse. After the tracer pulse, the forced gradient was maintained throughout the experiment using non-labeled groundwater. Tracer migration was monitored using a set of six sampling wells radially spaced at approximate distances of 1.5, 3, and 4.5 meters from a central injection well. Each sampling well was further divided into three discrete sampling depths that were monitored continuously throughout the course of the tracer experiment. At various time intervals, discrete groundwater samples were collected from all 18 sampling ports for tritium analysis. Longitudinal dispersivity for tritium breakthrough at each sampling location was estimated using analytical approximations of the convection dispersion equation (CDE) for radial flow assuming an instantaneous Dirac pulse and a pulse of known duration. The results were also compared to dispersivity values derived from fitting the tracer data to analytical solutions derived from assuming uniform flow conditions. Tremendous variation in dispersivity values and tracer arrival

  17. Flow of Magnetohydrodynamic Micropolar Fluid Induced by Radially Stretching Sheets

    NASA Astrophysics Data System (ADS)

    Hayat, Tasawar; Nawaz, Muhammad; Hendi, Awatif A.

    2011-02-01

    We investigate the flow of a micropolar fluid between radial stretching sheets. The magnetohydrodynamic (MHD) nonlinear problem is treated using the homotopy analysis method (HAM) and the velocity profiles are predicted for the pertinent parameters. The values of skin friction and couple shear stress coefficients are obtained for various values of Reynolds number, Hartman number, and micropolar fluid parameter.

  18. Radial Plasma Flow Switch on GIT-12 Generator

    NASA Astrophysics Data System (ADS)

    Chaikovsky, S. A.; Kokshenev, V. A.; Rousskikh, A. G.; Shishlov, A. V.; Fedunin, A. V.; Labetsky, A. Yu.; Kurmaev, N. E.; Fursov, F. I.

    2006-01-01

    The preliminary experiments were performed on wire array implosion driven by a radial plasma flow switch on the GIT-12 generator operating in a microsecond mode. Imploding gas puff z-pinch plasma was used to provide fast switching of the current to an aluminum wire array. The experimental results are presented in the paper.

  19. Linear stability of radially-heated circular Couette flow with simulated radial gravity

    NASA Astrophysics Data System (ADS)

    Tagg, Randy; Weidman, Patrick D.

    2007-05-01

    The stability of circular Couette flow between vertical concentric cylinders in the presence of a radial temperature gradient is considered with an effective “radial gravity.” In addition to terrestrial buoyancy - ρg e z we include the term - ρg m f(r)e r where g m f(r) is the effective gravitational acceleration directed radially inward across the gap. Physically, this body force arises in experiments using ferrofluid in the annular gap of a Taylor Couette cell whose inner cylinder surrounds a vertical stack of equally spaced disk magnets. The radial dependence f(r) of this force is proportional to the modified Bessel function K 1(κr), where 2π/κ is the spatial period of the magnetic stack and r is the radial coordinate. Linear stability calculations made to compare with conditions reported by Ali and Weidman (J. Fluid Mech., 220, 1990) show strong destabilization effects, measured by the onset Rayleigh number R, when the inner wall is warmer, and strong stabilization effects when the outer wall is warmer, with increasing values of the dimensionless radial gravity γ = g m /g. Further calculations presented for the geometry and fluid properties of a terrestrial laboratory experiment reveal a hitherto unappreciated structure of the stability problem for differentially-heated cylinders: multiple wavenumber minima exist in the marginal stability curves. Transitions in global minima among these curves give rise to a competition between differing instabilities of the same spiral mode number, but widely separated axial wavenumbers.

  20. Analysis and performance of radial flow rotary dessicant dehumidifiers

    SciTech Connect

    Elsayed, M.M.; Chamkha, A.J.

    1997-02-01

    A model is developed to predict the steady periodic performance of a radial flow desiccant wheel. The model is expressed in terms of the same dimensionless parameters that are commonly used in modeling of the conventional axial flow desiccant wheel. In addition a dimensionless geometrical ratio of the volume of the matrix to the volume of the wheel core is found to affect the performance of the wheel. A finite difference technique on staggered grid is used to discretize the governing dimensionless equations. The discretized equations are solved to predict the performance of the desiccant wheel at given values of operation parameters. A sensitivity study is carried out to investigate the effect of changing any of these parameters on the performance of the wheel. The performance of the radial flow desiccant wheel having the same values of the operation parameters.

  1. Non-radial flow in the solar wind

    NASA Technical Reports Server (NTRS)

    Richardson, J. D.; Paularena, K. I.; Gazis, P. R.

    1995-01-01

    Although the radial component of the solar wind dominates the solar wind speed, significant non-radial velocity components are also present. These flows are more difficult to measure accurately, but we now have data sets including the east-west (tangential) and north-south (normal) flows from PVO at Venus, IMP 8 at Earth, and Voyagers 1 and 2 from 1 to 45 AU. We compare the non-radial flow observations from these spacecraft. One of the more interesting features is that the north-south flow angle observed at Earth and Venus oscillates with the period of a local (Earth or Venus) year. These oscillations occur throughout two solar cycles in the IMP 8 data set and are very apparent in the PVO data from 1978 to 1986 but less obvious after this. We will report on the origin of this feature. The tangential flow observed by both IMP 8 and Voyager is on average slightly positive (approximately 1.75 km/s). The magnitudes of the nonradial velocity components decrease with distance from the Sun.

  2. FUEL SUBASSEMBLY CONSTRUCTION FOR RADIAL FLOW IN A NUCLEAR REACTOR

    DOEpatents

    Treshow, M.

    1962-12-25

    An assembly of fuel elements for a boiling water reactor arranged for radial flow of the coolant is described. The ingress for the coolant is through a central header tube, perforated with parallel circumferertial rows of openings each having a lip to direct the coolant flow downward. Around the central tube there are a number of equally spaced concentric trays, closely fitiing the central header tube. Cylindrical fuel elements are placed in a regular pattern around the central tube, piercing the trays. A larger tube encloses the arrangement, with space provided for upward flow of coolart beyond the edge of the trays. (AEC)

  3. Radial flow permeability testing of an argillaceous limestone.

    PubMed

    Selvadurai, A P S; Jenner, L

    2013-01-01

    Argillaceous Lindsay limestone is the geologic storage formation that will be encountered at the site for the construction of a deep ground repository in Ontario, Canada, for the storage of low to intermediate level nuclear waste. The permeability of the Lindsay limestone is a key parameter that will influence the long-term movement of radionuclides from the repository to the geosphere. This paper describes the use of both steady-state and transient radial flow laboratory tests to determine the permeability of this argillaceous limestone. The interpretation of the tests is carried out using both analytical results and computational models of flow problems that exhibit radial symmetry. The results obtained from this research investigation are compared with the data available in the literature for similar argillaceous limestones mainly found in the Lindsay (Cobourg) formation. The experiments give permeabilities in the range of 1.0 × 10(-22) to 1.68 × 10(-19) m(2) for radial flows that are oriented along bedding planes under zero axial stress. The factors influencing transient pulse tests in particular and the interpretation of the results are discussed. PMID:22489872

  4. Macrodispersion by diverging radial flows in randomly heterogeneous porous media

    NASA Astrophysics Data System (ADS)

    Severino, Gerardo; Santini, Alessandro; Sommella, Angelo

    2011-04-01

    Radial flow takes place in a heterogeneous porous formation where the transmissivity T is modelled as a stationary random space function ( RSF). The steady flow is driven by a given rate, and the mean velocity is radial. A pulse-like of a tracer is injected in the porous formation, and the thin plume spreads due to the fluctuations of the velocity which results a RSF as well. Transport is characterized by the mean front, and by the second spatial moment of the plume. We are primarily interested in tracer macrodispersion modelling. With the neglect of pore-scale dispersion, macrodispersion coefficients are computed at the second order of approximation, without neglecting the head-gradient fluctuations. Although transport is non-ergodic at the source, it is shown that ergodicity is achieved at small distances from the source. This is due to the fact that close to the source local velocities are quite large, and therefore solute particles become uncorrelated very soon. Under ergodic conditions, we compare macrodispersion mechanism in radial flows with that occurring in mean uniform flows. At short distances the spreading effect is highly enhanced by the large variability of the flow field, whereas at large distances transport exhibits a lesser dispersion due to the reduction of velocities. This supports the explanation provided by Indelman and Dagan (1999) to justify why the macrodispersivity is found smaller than that pertaining to mean uniform flows. The model is tested against a tracer transport experiment (Fernàndez-Garcia et al., 2004) by comparing the theoretical and experimental breakthrough curves. The accordance with real data, that is achieved without any fitting to concentration values, strengthens the capability of the proposed model to grasp the main features of such an experiment, the approximations as well as experimental uncertainties notwithstanding.

  5. The stability of Taylor-Couette flow with radial heating

    NASA Astrophysics Data System (ADS)

    Ali, Mohamed El-Sayed

    The stability of circular Couette flow with radial heating across vertically oriented coaxial cylinders is investigated using linearized stability theory. The physical problem is governed by five parameters: the Taylor number Ta, the Groshof number G, the Prandtl number Pr, the cylinder aspect ration A, and the radius ratio eta. In the model infinite aspect ratio is assumed and critical stability boundaries are calculated for a conduction regime base flow. A rational analysis is made to derive the full governing perturbation equations and test flow stability subject to both axisymmetric and nonaxisymmetric disturbances. The flow may be driven to instability by competition between centrifugal, buoyancy, and shear force mechanisms. In spite of this complexity, the existence of solution symmetries of the perturbation equations with respect to the sense of radial heating and the sense of cylinder rotation are proven. The linear boundary-value problem defined by 16 first-order differential equations is solved using the software package SUPORT in combination with the nonlinear equation solver SNSQE. Critical stability boundaries at fixed Pr and eta were determined by searching for the minimum value of either Ta or G over all wavelengths K and mode numbers n.

  6. Radial accretion flows on static spherically symmetric black holes

    NASA Astrophysics Data System (ADS)

    Chaverra, Eliana; Sarbach, Olivier

    2015-08-01

    We analyze the steady radial accretion of matter into a nonrotating black hole. Neglecting the self-gravity of the accreting matter, we consider a rather general class of static, spherically symmetric and asymptotically flat background spacetimes with a regular horizon. In addition to the Schwarzschild metric, this class contains certain deformation of it, which could arise in alternative gravity theories or from solutions of the classical Einstein equations in the presence of external matter fields. Modeling the ambient matter surrounding the black hole by a relativistic perfect fluid, we reformulate the accretion problem as a dynamical system, and under rather general assumptions on the fluid equation of state, we determine the local and global qualitative behavior of its phase flow. Based on our analysis and generalizing previous work by Michel, we prove that for any given positive particle density number at infinity, there exists a unique radial, steady-state accretion flow which is regular at the horizon. We determine the physical parameters of the flow, including its accretion and compression rates, and discuss their dependency on the background metric.

  7. Onset of radial flow in p+p collisions

    DOE PAGESBeta

    Jiang, Kun; Zhu, Yinying; Liu, Weitao; Chen, Hongfang; Li, Cheng; Ruan, Lijuan; Tang, Zebo; Xu, Zhangbu

    2015-02-23

    It has been debated for decades whether hadrons emerging from p+p collisions exhibit collective expansion. The signal of the collective motion in p+p collisions is not as clear as in heavy-ion collisions because of the low multiplicity and large fluctuation in p+p collisions. Tsallis Blast-Wave (TBW) model is a thermodynamic approach, introduced to handle the overwhelming correlation and fluctuation in the hadronic processes. We have systematically studied the identified particle spectra in p+p collisions from RHIC to LHC using TBW and found no appreciable radial flow in p+p collisions below √s = 900 GeV. At LHC higher energy of 7more » TeV in p+p collisions, the radial flow velocity achieves an average of (β) = 0.320 ± 0.005. This flow velocity is comparable to that in peripheral (40-60%) Au+Au collisions at RHIC. In addition, breaking of the identified particle spectra mT scaling was also observed at LHC from a model independent test.« less

  8. Onset of radial flow in p +p collisions

    NASA Astrophysics Data System (ADS)

    Jiang, Kun; Zhu, Yinying; Liu, Weitao; Chen, Hongfang; Li, Cheng; Ruan, Lijuan; Tang, Zebo; Xu, Zhangbu

    2015-02-01

    It has been debated for decades whether hadrons emerging from p +p collisions exhibit collective expansion. The signal of the collective motion in p +p collisions is not as clear or as clean as in heavy-ion collisions because of the low multiplicity and large fluctuation in p +p collisions. The Tsallis blast-wave (TBW) model is a thermodynamic approach, introduced to handle the overwhelming correlation and fluctuation in the hadronic processes. We have systematically studied the identified particle spectra in p +p collisions from the BNL Relativistic Heavy Ion Collider (RHIC) to the CERN Large Hadron Collider (LHC) using TBW and have found no appreciable radial flow in p +p collisions below √{s }=900 GeV. At the LHC higher energy of 7 TeV in p +p collisions, the radial flow velocity achieves an average value of <β >=0.320 ±0.005 . This flow velocity is comparable to that in peripheral (40-60%) Au +Au collisions at the RHIC. Breaking of the identified particle spectra mT scaling was also observed at the LHC from a model-independent test.

  9. Multiphase flow modeling in centrifugal partition chromatography.

    PubMed

    Adelmann, S; Schwienheer, C; Schembecker, G

    2011-09-01

    The separation efficiency in Centrifugal Partition Chromatography (CPC) depends on selection of a suitable biphasic solvent system (distribution ratio, selectivity factor, sample solubility) and is influenced by hydrodynamics in the chambers. Especially the stationary phase retention, the interfacial area for mass transfer and the flow pattern (backmixing) are important parameters. Their relationship with physical properties, operating parameters and chamber geometry is not completely understood and predictions are hardly possible. Experimental flow visualization is expensive and two-dimensional only. Therefore we simulated the flow pattern using a volume-of-fluid (VOF) method, which was implemented in OpenFOAM®. For the three-dimensional simulation of a rotating FCPC®-chamber, gravitational centrifugal and Coriolis forces were added to the conservation equation. For experimental validation the flow pattern of different solvent systems was visualized with an optical measurement system. The amount of mobile phase in a chamber was calculated from gray scale values of videos recorded by an image processing routine in ImageJ®. To visualize the flow of the stationary phase polyethylene particles were used to perform a qualitative particle image velocimetry (PIV) analysis. We found a good agreement between flow patterns and velocity profiles of experiments and simulations. By using the model we found that increasing the chamber depth leads to higher specific interfacial area. Additionally a circular flow in the stationary phase was identified that lowers the interfacial area because it pushes the jet of mobile phase to the chamber wall. The Coriolis force alone gives the impulse for this behavior. As a result the model is easier to handle than experiments and allows 3D prediction of hydrodynamics in the chamber. Additionally it can be used for optimizing geometry and operating parameters for given physical properties of solvent systems. PMID:21324465

  10. Exact Convex Relaxation of Optimal Power Flow in Radial Networks

    SciTech Connect

    Gan, LW; Li, N; Topcu, U; Low, SH

    2015-01-01

    The optimal power flow (OPF) problem determines a network operating point that minimizes a certain objective such as generation cost or power loss. It is nonconvex. We prove that a global optimum of OPF can be obtained by solving a second-order cone program, under a mild condition after shrinking the OPF feasible set slightly, for radial power networks. The condition can be checked a priori, and holds for the IEEE 13, 34, 37, 123-bus networks and two real-world networks.

  11. A visual study of radial inward choked flow of liquid nitrogen

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Simoneau, R. J.; Hsu, Y. Y.

    1973-01-01

    A visual study of the radial inward choked flow of liquid nitrogen was conducted. Data and high speed moving pictures were obtained. The study indicated the following: (1) steady radial inward choked flow seems equivalent to steady choked flow through axisymmetric nozzles, (2) transient choked flows through the radial gap are not uniform and the discharge pattern appears as nonuniform impinging jets, and (3) the critical mass flow rate data for the transient case appear different from those of the steady case.

  12. Linear and radial flow targets for characterizing downhole flow in perforations

    SciTech Connect

    Deo, M. ); Tariq, S.M. ); Halleck, P.M. )

    1989-08-01

    Two types of sandstone targets are commonly used to test flow efficiency of shaped-charge jet perforations: linear targets, in which flow enters only the unperforated end of the cylindrical sample, and radial targets, in which flow enters through the end and sides of the sample. To determine which of these targets best represents downhole conditions, the flow distribution along the length of a perforation has been studied by three-dimensional (3D) finite-element analyses. Linear and radial laboratory targets have been compared with downhole perforations under varying conditions. For ideal perforations, the low-shot-density (LSD) case is adequately represented by the radial target, while the high-shot-density (HSD) case falls between the two targets. With realistic crushed and damaged zones, the HSD closely matches the linear target, and the LSD case falls between the two targets.

  13. Separation of Metal Complexes with Counter Ions by Tube Radial Distribution Chromatography Using a Ternary Solvent Containing 8-quinolinol.

    PubMed

    Kawai, Yuji; Fujinaga, Satoshi; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

    2015-01-01

    An open-tubular capillary chromatography system (tube radial distribution chromatography, TRDC) was developed using a ternary solvent (water-acetonitrile-ethyl acetate; volume ratio, 3:8:4) containing 10 mmol L(-1) 8-quinolinol for the separation of nitrate, chloride, and sulfate compounds of Ni(II), Al(III), and Fe(III). When a mixed solution of the Ni(II) compounds was injected into an untreated fused-silica capillary tube (90 cm × 75 μm i.d.) with a ternary solvent flow rate of 0.8 μL min(-1), the compounds were eluted in the following order: [Ni(II)-(8-quinolinol)3] complex, [Ni(II)-(8-quinolinol)]-nitrate ion interaction complex, [Ni(II)-(8-quinolinol)]-chloride ion interaction complex, and [Ni(II)-(8-quinolinol)]-sulfate ion interaction complex. The elution of mixtures of the Al(III) and Fe(III) compounds showed similar trends. PMID:26561263

  14. Boiling radial flow in fractures of varying wall porosity

    SciTech Connect

    Barnitt, Robb Allan

    2000-06-01

    The focus of this report is the coupling of conductive heat transfer and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed differences in boiling regimes and behavior, and attempted to quantify a boiling convection coefficient. The experimental study involved boiling radial flow in a simulated fracture, bounded by a variety of materials. Nonporous and impermeable aluminum, highly porous and permeable Berea sandstone, and minimally porous and permeable graywacke from The Geysers geothermal field. On nonporous surfaces, the heat flux was not strongly coupled to injection rate into the fracture. However, for porous surfaces, heat flux, and associated values of excess temperature and a boiling convection coefficient exhibited variation with injection rate. Nucleation was shown to occur not upon the visible surface of porous materials, but a distance below the surface, within the matrix. The depth of boiling was a function of injection rate, thermal power supplied to the fracture, and the porosity and permeability of the rock. Although matrix boiling beyond fracture wall may apply only to a finite radius around the point of injection, higher values of heat flux and a boiling convection coefficient may be realized with boiling in a porous, rather than nonporous surface bounded fracture.

  15. Forced-flow planar chromatography in the rear view mirror.

    PubMed

    Kalász, Huba

    2015-03-01

    Mobile phase progress in planar stationary phase can be evoked by either external or internal forces. An internal force is capillarity, while gravity, electric field, a pump and centrifugal forces belong to external forces. Overpressured layer chromatography gives a widely used special chapter of forced-flow planar chromatography, a special bridge between high-performance liquid column chromatography and thin-layer chromatography (TLC). A simple and special rule characterizes the progress of mobile phase. Optimal efficiency is composed by the doubled effect of flow resulting from the pump-forced mobile phase (convex profile of laminar flow) and capillary forces on the dry stationary phase (concave laminar flow). This review describes the most important aspects of forced-flow TLC, including how the set-ups are developed and also the progress of detection methods used. PMID:25681205

  16. An investigation of radial tracer flow in naturally fractured reservoirs

    SciTech Connect

    Jetzabeth, Ramirez-Sabag; Fernando, Samaniego V.; Jesus, Rivera R.; Fernando Rodriguez

    1991-01-01

    This study presents a general solution for the radial flow of tracers in naturally fractured reservoirs. Continuous and finite step injection of chemical and radioactive tracers are considered. The reservoir is treated as being composed of two regions: a mobile region where longitudinal dispersion and convection take place and a stagnant region where only diffusion and adsorption are allowed. Radioactive decay is considered in both regions. The model of this study is thoroughly compared to those previously presented in literature by Moench and Ogata, Tang et al., Chen et al., and Hsieh et al. The solution is numerically inverted by means of the Crump algorithm. A detailed validation of the model with respect to solutions previously presented and/or simplified physical conditions solutions (i.e., homogeneous case) or limit solutions (i.e., for short times) was carried out. The influence of various dimensionless parameters that enter into the solution was investigated. A discussion of results obtained through the Crump and Stehfest algorithm is presented, concluding that the Crump method provides more reliable tracer concentrations.

  17. A visual study of radial inward choked flow of liquid nitrogen.

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Simoneau, R. J.; Hsu, Y. Y.

    1973-01-01

    Data and high speed movies were acquired on pressurized subcooled liquid nitrogen flowing radially inward through a 0.0076 cm gap. The stagnation pressure ranged from 0.7 to 4 MN/sq m. Steady radial inward choked flow appears equivalent to steady choked flow through axisymmetric nozzles. Transient choked flows through the radial gap are not uniform and the discharge pattern appears as nonuniform impinging jets. The critical mass flow rate data for the transient case appear different from those for the steady case. On the mass flow rate vs pressure map, the slope and separation of the isotherms appear to be less for transient than for steady radial choked flow.

  18. Computational investigations of axial and radial flow compressor aeromechanics

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Kishore

    The focus of this research is aeromechanics issues in advanced compressors of the type used in modern day high thrust-to-weight ratio aircraft gas turbine engines. The driving factor for the studies undertaken is the High Cycle Fatigue (HCF) failure of gas turbine blades. HCF is a key technology issue in the development and endurance of gas turbine engines that arises primarily due to resonant response of turbomachine blading to unsteady aerodynamic excitation. Because it is a truly coupled nonlinear fluid-structure problem, predicting HCF requires a unified approach to modeling both the fluid and the structure. Considering the serious nature of HCF and the inadequacy of lower order design systems to accurately predict blade vibratory stress, the need to develop advanced predictive tools is pressing. The first aspect of this research therefore addresses the development of a turbomachinery coupled fluid-structure interaction tool to predict flow-induced blade vibration. To this end, the TAM-ALE3D solver is further developed as a derivative of the ALE3D code of Lawrence Livermore National Laboratory. In the second aspect of this research, TAM-ALE3D is validated by predicting viscous blade row unsteady aerodynamics and the modal properties of the stator vane in the baseline configuration of the Purdue Transonic Compressor. It is then used to predict the vane vibratory response excited by rotor wakes at resonance, with the resulting stresses in the range expected. For radial flow compressors, a very limited knowledge base exists on the unsteady aerodynamic and aeroelastic mechanisms that result in HCF. The bulk of this research is thus directed at the understanding of these fundamental unsteady phenomena using TAM-ALE3D as an investigative tool. The energy transfer from the downstream diffuser generated forcing function to the impeller blading is addressed by means of unsteady aerodynamic and aeroelastic analyses. From these computational investigations, the details of

  19. Flow field thermal gradient gas chromatography.

    PubMed

    Boeker, Peter; Leppert, Jan

    2015-09-01

    Negative temperature gradients along the gas chromatographic separation column can maximize the separation capabilities for gas chromatography by peak focusing and also lead to lower elution temperatures. Unfortunately, so far a smooth thermal gradient over a several meters long separation column could only be realized by costly and complicated manual setups. Here we describe a simple, yet flexible method for the generation of negative thermal gradients using standard and easily exchangeable separation columns. The measurements made with a first prototype reveal promising new properties of the optimized separation process. The negative thermal gradient and the superposition of temperature programming result in a quasi-parallel separation of components each moving simultaneously near their lowered specific equilibrium temperatures through the column. Therefore, this gradient separation process is better suited for thermally labile molecules such as explosives and natural or aroma components. High-temperature GC methods also benefit from reduced elution temperatures. Even for short columns very high peak capacities can be obtained. In addition, the gradient separation is particularly beneficial for very fast separations below 1 min overall retention time. Very fast measurements of explosives prove the benefits of using negative thermal gradients. The new concept can greatly reduce the cycle time of high-resolution gas chromatography and can be integrated into hyphenated or comprehensive gas chromatography setups. PMID:26235451

  20. Buoyancy-driven flow reversal phenomena in radially rotating serpentine ducts

    SciTech Connect

    Hwang, J.J.; Wang, W.J.; Chen, C.K.

    2000-02-01

    Convective characteristics are analyzed numerically in a rotating multipass square duct connecting with 180-deg sharp returns. Isoflux is applied to each duct wall and periodic conditions are used between the entrance and exit of a typical two-pass module. Emphasis is placed on the phenomenon of buoyancy-driven reversed flow in the serpentine duct. Predictions reveal that the radial distance from the rotational axis to the location of flow separation in the radial-outward duct decreases with increasing the Richardson number. In addition, the local buoyancy that is required to yield the radial flow reversal increases with increasing the rotation number. This buoyancy-driven reversed flow in the radial-outward duct always results in local hot spots in the cooling channels. The critical buoyancy for the initiation of flow reversal is therefore concluded for the design purpose.

  1. One-dimensional analysis of plane and radial thin film flows including solid-body rotation

    NASA Technical Reports Server (NTRS)

    Thomas, S.; Hankey, W.; Faghri, A.; Swanson, T.

    1989-01-01

    The flow of a thin liquid film with a free surface along a horizontal plate which emanates from a pressurized vessel is examined by integrating the equations of motion across the thin liquid layer and discretizing the integrated equations using finite difference techniques. The effects of 0-g and solid-body rotation will be discussed. The two cases of interest are plane flow and radial flow. In plane flow, the liquid is considered to be flowing along a channel with no change in the width of the channel, whereas in radial flow the liquid spreads out radially over a disk, so that the area changes along the radius. It is desired to determine the height of the liquid film at any location along the plate of disk, so that the heat transfer from the plate or disk can be found. The possibility that the flow could encounter a hydraulic jump is accounted for.

  2. Detailed kinetic performance analysis of micromachined radially elongated pillar array columns for liquid chromatography.

    PubMed

    Callewaert, Manly; Desmet, Gert; Ottevaere, Heidi; De Malsche, Wim

    2016-02-12

    The individual factors that determine the kinetic performance (B- and C-term band broadening and bed permeability Kv) of radially elongated pillar (REP) columns are studied. To this end, columns with REPs having 4 different aspect ratios (AR=9, 12, 15, 20) were characterized experimentally and by means of numerical simulations. A tortuosity and retention based plate height equation was established, enabling a good global fit for all studied conditions. The B-term plate height contribution appears to decrease with a factor equaling the square of the flow path tortuosity τ. Going from AR=12 to AR=20 (τ=5.7 and τ=9.0 respectively), this resulted in a shift in plate height expressed in axial coordinates from Hmin=0.42 μm to Hmin=0.25 for non-retained conditions and from H=0.77 μm to H=0.57 μm for a component with k=1.0. The obtained parameters were combined to predict optimal time-efficiency combinations for all possible channel lengths. This revealed an efficiency limit of N=10(7) plates for a non-retained component and N=7-8 × 10(6) for k=1 for a channel with an AR=20, corresponding to a channel length of 2.5m and a void time of 2.4h. PMID:26795281

  3. Radial Motions in Disk Stars: Ellipticity or Secular Flows?

    NASA Astrophysics Data System (ADS)

    López-Corredoira, M.; González-Fernández, C.

    2016-06-01

    Average stellar orbits of the Galactic disk may have some small intrinsic ellipticity which breaks the exact axisymmetry and there may also be some migration of stars inwards or outwards. Both phenomena can be detected through kinematic analyses. We use the red clump stars selected spectroscopically from the APO Galactic Evolution Experiment, with known distances and radial velocities, to measure the radial component of the Galactocentric velocities within 5 kpc < R < 16 kpc, | b| \\lt 5^\\circ , and within 20° from the Sun–Galactic center line. The average Galactocentric radial velocity is VR = (1.48 ± 0.35)[R(kpc) ‑ (8.8 ± 2.7)] km s‑1 outwards in the explored range, with a higher contribution from stars below the Galactic plane. Two possible explanations can be given for this result: (i) the mean orbit of the disk stars is intrinsically elliptical with a Galactocentric radial gradient of eccentricity around 0.01 kpc‑1 or (ii) there is a net secular expansion of the disk, in which stars within R ≈ 9–11 kpc are migrating to the region R ≳ 11 kpc at the rate of ∼2 M⊙ yr‑1, and stars with R ≲ 9 kpc are falling toward the center of the Galaxy. This migration ratio would be unattainable for a long time and should decelerate, otherwise the Galaxy would fade away in around 1 Gyr. At present, both hypotheses are speculative and one would need data on the Galactocentric radial velocities for other azimuths different to the center or anticenter in order to confirm one of the scenarios.

  4. On the Problem of Theoretical Pressure of a Radial-Flow Pump Unit

    NASA Astrophysics Data System (ADS)

    Pavlechko, V. N.; Protasov, S. K.

    2014-11-01

    An analysis has been made of the velocity of motion of a medium in the wheel of a radial-flow pump unit under the action of a centrifugal force and overcoming the medium's inertial force with its blades. Relations for the pressure produced by the radial-flow pump unit as a function of the angle of inclination of its blades have been derived. The well-known Euler equation describing the dynamic pressure of the radial-flow pump unit has been supplemented to determine its static pressure. An analysis of the obtained results has shown that the pressure of the radial-flow pump unit is maximum at an angle of inclination of its blades of 110o and negative at 140o or larger angles.

  5. Computer program for the analysis of the cross flow in a radial inflow turbine scroll

    NASA Technical Reports Server (NTRS)

    Hamed, A.; Abdallah, S.; Tabakoff, W.

    1977-01-01

    A computer program was used to solve the governing of the potential flow in the cross sectional planes of a radial inflow turbine scroll. A list of the main program, the subroutines, and typical output example are included.

  6. 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

  7. Energy measurement using flow computers and chromatography

    SciTech Connect

    Beeson, J.

    1995-12-01

    Arkla Pipeline Group (APG), along with most transmission companies, went to electronic flow measurement (EFM) to: (1) Increase resolution and accuracy; (2) Real time correction of flow variables; (3) Increase speed in data retrieval; (4) Reduce capital expenditures; and (5) Reduce operation and maintenance expenditures Prior to EFM, mechanical seven day charts were used which yielded 800 pressure and differential pressure readings. EFM yields 1.2-million readings, a 1500 time improvement in resolution and additional flow representation. The total system accuracy of the EFM system is 0.25 % compared with 2 % for the chart system which gives APG improved accuracy. A typical APG electronic measurement system includes a microprocessor-based flow computer, a telemetry communications package, and a gas chromatograph. Live relative density (specific gravity), BTU, CO{sub 2}, and N{sub 2} are updated from the chromatograph to the flow computer every six minutes which provides accurate MMBTU computations. Because the gas contract length has changed from years to monthly and from a majority of direct sales to transports both Arkla and its customers wanted access to actual volumes on a much more timely basis than is allowed with charts. The new electronic system allows volumes and other system data to be retrieved continuously, if EFM is on Supervisory Control and Data Acquisition (SCADA) or daily if on dial up telephone. Previously because of chart integration, information was not available for four to six weeks. EFM costs much less than the combined costs of telemetry transmitters, pressure and differential pressure chart recorders, and temperature chart recorder which it replaces. APG will install this equipment on smaller volume stations at a customers expense. APG requires backup measurement on metering facilities this size. It could be another APG flow computer or chart recorder, or the other companies flow computer or chart recorder.

  8. Standard Flow Liquid Chromatography for Shotgun Proteomics in Bioenergy Research

    PubMed Central

    González Fernández-Niño, Susana M.; Smith-Moritz, A. Michelle; Chan, Leanne Jade G.; Adams, Paul D.; Heazlewood, Joshua L.; Petzold, Christopher J.

    2015-01-01

    Over the past 10 years, the bioenergy field has realized significant achievements that have encouraged many follow on efforts centered on biosynthetic production of fuel-like compounds. Key to the success of these efforts has been transformational developments in feedstock characterization and metabolic engineering of biofuel-producing microbes. Lagging far behind these advancements are analytical methods to characterize and quantify systems of interest to the bioenergy field. In particular, the utilization of proteomics, while valuable for identifying novel enzymes and diagnosing problems associated with biofuel-producing microbes, is limited by a lack of robustness and limited throughput. Nano-flow liquid chromatography coupled to high-mass accuracy, high-resolution mass spectrometers has become the dominant approach for the analysis of complex proteomic samples, yet such assays still require dedicated experts for data acquisition, analysis, and instrument upkeep. The recent adoption of standard flow chromatography (ca. 0.5 mL/min) for targeted proteomics has highlighted the robust nature and increased throughput of this approach for sample analysis. Consequently, we assessed the applicability of standard flow liquid chromatography for shotgun proteomics using samples from Escherichia coli and Arabidopsis thaliana, organisms commonly used as model systems for lignocellulosic biofuels research. Employing 120 min gradients with standard flow chromatography, we were able to routinely identify nearly 800 proteins from E. coli samples; while for samples from Arabidopsis, over 1,000 proteins could be reliably identified. An examination of identified peptides indicated that the method was suitable for reproducible applications in shotgun proteomics. Standard flow liquid chromatography for shotgun proteomics provides a robust approach for the analysis of complex samples. To the best of our knowledge, this study represents the first attempt to validate the standard

  9. Radial and elliptic flow at RHIC: Further predictions

    SciTech Connect

    Huovinen, Pasi; Kolb, Peter F.; Heinz, Ulrich; Ruuskanen, P.V.; Voloshin, Sergei A.

    2001-01-30

    Using a hydrodynamic model, we predict the transverse momentum dependence of the spectra and the elliptic flow for different hadrons in Au+Au collisions at sqrt(s)=130 AGeV. The dependence of the differential and p{_}t-integrated elliptic flow on the hadron mass, equation of state and freeze-out temperature is studied both numerically and analytically.

  10. Transient radial flow to a well in an unconfined aquifer

    SciTech Connect

    Narasimhan, T.N.; Zhu, Ming.

    1991-08-01

    The analytic solutions of Boulton (1954) and Neuman (1972) for transient flow to a well in an unconfined aquifer are based on the assumption that the role of the unsaturated zone can be adequately accounted for by restricting attention to the release of water from the zone through which the water table moves. Both researchers mathematically treat this released water as a time-dependent source term. The differences between the models of Boulton and Neuman are that the former neglects vertical components of flow in the aquifer, but allows for an exponential process for the release of water as a function of time, whereas the latter assumes instantaneous release from storage, but accounts for vertical components of flow. Given this set of assumptions, we examine the applicability of these two methods using a general purpose numerical model through a process of verification extension and comparison. The issues addressed include: the role of well-bore storage in masking intermediate-time behavior, combined effects of exponential release as well as vertical flow, logic for vertical averaging of drawdowns, and the sensitivity of system response to the magnitude of specific yield. The issue of how good the assumptions of Boulton and Neuman are in the context of the general theory of unsaturated flow is addressed in part 2 of this two-part series of reports.

  11. Three Phase Probabilistic Load Flow in Radial Distribution Networks

    SciTech Connect

    Melhorn, Alexander C; Dimitrovski, Aleksandar D; Tomsovic, Kevin L

    2012-01-01

    Probabilistic load flow is a helpful tool in accounting for inconsistent or unknown loads and generation. This is especially true with the push for renewable generation and demand response. This paper proposes an improved version of the probabilistic load flow solution for balanced distribution systems and takes the next step by applying it to unbalanced three phase systems. It is validated by comparing the solutions to that obtained by Monte Carlo simulation. The proposed method provides an accurate and practical way for finding the solution to the stochastic problems occurring in power distribution system analysis today.

  12. Phase Change Effects on Immiscible Flow Displacements in Radial Injection

    NASA Astrophysics Data System (ADS)

    Ahmadlouydarab, Majid; Azaiez, Jalel; Chen, Zhangxin

    2014-11-01

    We report a systematic simulation of immiscible fluid-fluid displacements in radial injection in the presence of phase change. Due to the presence of two fluid-fluid interfaces in the system, a special treatment has been adopted. To track the leading interface position, two highly accurate methods including Level Set and Immersed Interface Method were used, while for locating the trailing interface an energy equation was adopted assuming the existence of a constant thin condensate layer. Dimensional analysis led to three important dimensionless groups including capillary number (Ca), Jacob number (Ja) and viscosity ratios (M) of the three fluids. Simulation results indicate significant influences of these parameters on the development of the instability and the interfacial morphology of fingers. Increasing Ca or M tends to amplify the interfacial instability, fingertip splitting, and results in longer fingers. In contrast, increasing Ja has stabilizing effects due to an increase of the thickness of the condensate layer. On the other hand at lower viscosity ratios as well as lower Ca, because of compensation effects of the phase change, both leading and trailing interfaces are found to be less unstable. Moreover accumulated condensate and oil saturation depletion curves show increasing and decreasing trends, respectively, when the Ca increases. Although viscosity ratio and Ja have similar effects on the accumulated condensate, they do not show any effect on the oil depletion saturation.

  13. Investigations on the Aerodynamic Characteristics and Blade Excitations of the Radial Turbine with Pulsating Inlet Flow

    NASA Astrophysics Data System (ADS)

    Liu, Yixiong; Yang, Ce; Yang, Dengfeng; Zhang, Rui

    2016-04-01

    The aerodynamic performance, detailed unsteady flow and time-based excitations acting on blade surfaces of a radial flow turbine have been investigated with pulsation flow condition. The results show that the turbine instantaneous performance under pulsation flow condition deviates from the quasi-steady value significantly and forms obvious hysteretic loops around the quasi-steady conditions. The detailed analysis of unsteady flow shows that the characteristic of pulsation flow field in radial turbine is highly influenced by the pulsation inlet condition. The blade torque, power and loading fluctuate with the inlet pulsation wave in a pulse period. For the blade excitations, the maximum and the minimum blade excitations conform to the wave crest and wave trough of the inlet pulsation, respectively, in time-based scale. And toward blade chord direction, the maximum loading distributes along the blade leading edge until 20% chord position and decreases from the leading to trailing edge.

  14. Flow behavior in inlet guide vanes of radial turbines

    NASA Technical Reports Server (NTRS)

    Sokhey, J.; Tabakoff, W.; Hosny, W. M.

    1975-01-01

    Scroll flow is discussed. Streamline pattern and velocity distribution in the guide vanes are calculated. The blade surface temperature distribution is also determined. The effects of the blade shapes and the nozzle channel width on the velocity profiles at inlet to the guide vanes are investigated.

  15. Fluctuations of harmonic and radial flow in heavy ion collisions with principal components

    NASA Astrophysics Data System (ADS)

    Mazeliauskas, Aleksas; Teaney, Derek

    2016-02-01

    We analyze the spectrum of harmonic flow, vn(pT) for n =0 -5 , in event-by-event hydrodynamic simulations of Pb+Pb collisions at the CERN Large Hadron Collider (√{sN N}=2.76 TeV ) with principal component analysis (PCA). The PCA procedure finds two dominant contributions to the two-particle correlation function. The leading component is identified with the event plane vn(pT) , while the subleading component is responsible for factorization breaking in hydrodynamics. For v0, v1, and v3 the subleading flow is a response to the radial excitation of the corresponding eccentricity. By contrast, for v2 the subleading flow in peripheral collisions is dominated by the nonlinear mixing between the leading elliptic flow and radial flow fluctuations. In the v2 case, the sub-sub-leading mode more closely reflects the response to the radial excitation of ɛ2. A consequence of this picture is that the elliptic flow fluctuations and factorization breaking change rapidly with centrality, and in central collisions (where the leading v2 is small and nonlinear effects can be neglected) the sub-sub-leading mode becomes important. Radial flow fluctuations and nonlinear mixing also play a significant role in the factorization breaking of v4 and v5. We construct good geometric predictors for the orientation and magnitudes of the leading and subleading flows based on a linear response to the geometry, and a quadratic mixing between the leading principal components. Finally, we suggest a set of measurements involving three point correlations which can experimentally corroborate the nonlinear mixing of radial and elliptic flow and its important contribution to factorization breaking as a function of centrality.

  16. Preprocessor and postprocessor computer programs for a radial-flow finite-element model

    USGS Publications Warehouse

    Pucci, A.A., Jr.; Pope, D.A.

    1987-01-01

    Preprocessing and postprocessing computer programs that enhance the utility of the U.S. Geological Survey radial-flow model have been developed. The preprocessor program: (1) generates a triangular finite element mesh from minimal data input, (2) produces graphical displays and tabulations of data for the mesh , and (3) prepares an input data file to use with the radial-flow model. The postprocessor program is a version of the radial-flow model, which was modified to (1) produce graphical output for simulation and field results, (2) generate a statistic for comparing the simulation results with observed data, and (3) allow hydrologic properties to vary in the simulated region. Examples of the use of the processor programs for a hypothetical aquifer test are presented. Instructions for the data files, format instructions, and a listing of the preprocessor and postprocessor source codes are given in the appendixes. (Author 's abstract)

  17. Travel time statistics under radially converging flow in single fractures

    NASA Astrophysics Data System (ADS)

    Gotovac, Hrvoje; Srzic, Veljko; Cvetkovic, Vladimir; Kekez, Toni; Malenica, Luka

    2015-04-01

    A stochastic methodology based on Adaptive Fup Monte Carlo Method is used to investigate transport of a conservative solute by steady flow to a single pumping well in two-dimensional randomly heterogeneous single fractures. The spatially variable hydraulic transmissivity is modeled as a stationary random function for three different correlation structures (multi-Gaussian, connected and disconnected fields with correlated mean, high and low lnT values, respectively, according to the Zinn and Harvey, 2003) and heterogeneity levels (lnT variance is 1 and 8). Initially, solute particles are injected at outer circle located at 32 correlation lengths from well according to the in flux and resident injection mode. Therefore, breakthrough curve (BTC) statistics in single well due to different spatial structures, heterogeneity levels, injection modes and dispersion influence is considered. For small heterogeneity, all considered effects have small influences on BTC and related moments. As expected in single fractures, high lnT variance is more usual case which considerably changes flow patterns including channelling effect and fact that only few narrow channels carry out most pumping flow rate. Channelling implies significant differences between different injection modes. Resident mode uniformly injects particles implying that most particles pass through "slower" zones that especially increase late arrivals and contribute to the non-Fickian behaviour of transport. Contrary, "in flux" mode drastically reduces first arrivals and mean values, especially for connected correlation fields. The results from two injection modes lie on different sides of homogeneous mean travel time solution and give complementary information for complete representation of conservative transport. For advection transport, correlation structure and especially lnT variance seems to have major influence on BTC characteristics. On the other side, influence of longitudinal and lateral local scale

  18. 3-D model of a radial flow sub-watt methanol fuel processor

    SciTech Connect

    Holladay, J. D.; Wang, Y.

    2015-10-01

    A 3-D model is presented for a novel sub-watt packed bed reactor. The reactor uses an annular inlet flow combined with a radial flow packed bed reactor. The baseline reactor is compared to a reactor with multiple outlets and a reactor with 3 internal fins. Increasing the outlets from 1 to 4 did improve the flow distribution, but did not increase the performance in the simulation. However, inserting fins allowed a decrease in temperature with same inlet flow of approximately 35K. Or the inlet flow rate could be increased by a factor of 2.8x while maintaining >99% conversion.

  19. EXPERIMENTAL CHARACTERIZATION OF COHERENT, RADIALLY-SHEARED ZONAL FLOWS IN THE DIII-D TOKAMAK

    SciTech Connect

    MCKEE,GR; FONCK,RJ; JAKUBOWSKI,M; BURRELL,KH; HALLATSCHEK,K; MOYER,RA; NEVINS,W; PORTER,GD; RUDAKOV,DL; XU,X

    2002-11-01

    A271 EXPERIMENTAL CHARACTERIZATION OF COHERENT, RADIALLY-SHEARED ZONAL FLOWS IN THE DIII-D TOKAMAK. Application of time-delay-estimation techniques to two-dimensional measurements of density fluctuations, obtained with beam emission spectroscopy in DIII-D plasmas, has provided temporally and spatially resolved measurements of the turbulence flow-field. Features that are characteristic of self-generated zonal flows are observed in the radial region near 0.85 {<=} r/a {<=} 1.0. These features include a coherent oscillation (approximately 15 kHz) in the poloidal flow of density fluctuations that has a long poloidal wavelength, possibly m = 0, narrow radial extent (k{sub r}{rho}{sub I} < 0.2), and whose frequency varies monotonically with the local temperature. The approximate effective shearing rate, dv{sub {theta}}/dr, of the flow is of the same order of magnitude as the measured nonlinear decorrelation rate of the turbulence, and the density fluctuation amplitude is modulated at the frequency of the observed flow oscillation. Some phase coherence is observed between the higher wavenumber density fluctuations and low frequency poloidal flow fluctuations, suggesting a Reynolds stress contribution. These characteristics are consistent with predicted features of zonal flows, specifically identified as geodesic acoustic modes, observed in 3-D Braginskii simulations of core/edge turbulence.

  20. Origin and stability of radial density stratification in vortical flow

    NASA Astrophysics Data System (ADS)

    Dixit, Harish; Govindarajan, Rama

    2009-11-01

    A density interface near a vortex winds into a spiral. In the absence of gravity we have shown numerically and through stability analysis that this leads to spiral Kelvin-Helmholtz and centrifugal Rayleigh-Taylor (CRT) instabilities, often reducing the life-time of the vortex dramatically. In this talk we focus on CRT instability, which is driven by centrifugal forces, so flows where the vortex core is heavier than the surroundings are expected to be unstable. Indeed, Sipp et al. (JFM, 2005) and Joly et al. (JFM, 2005), prescribing Gaussian vorticity and density profiles, find no instability in light-cored vortices. Surprisingly however, for some range of parameters, with a Rankine vortex and a step circular density jump we find that making the core lighter can lead to instability. The sharpness of the profiles are thus relevant. The mechanism for this instability, studied by constructing planar analogues in the form of stratified shear flows, bearing similarities with Craik & Adams (JFM, 1979), will be discussed. So will the nonlinear stages of these instabilities from our direct numerical simulations.

  1. Chromatography.

    ERIC Educational Resources Information Center

    Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

    This booklet presents some activities on chromatography. Directions for preparing leaf pigment extracts using alcohol are given, and paper chromatography and thin-layer chromatography are described as modifications of the basic principles of chromatography. (KHR)

  2. Radial heterogeneity of some analytical columns used in high-performance liquid chromatography

    SciTech Connect

    Mriziq, Khaled S; Guiochon, Georges A

    2009-01-01

    An on-column electrochemical microdetector was used to determine accurately the radial distribution of the mobile phase velocity and of the column efficiency at the exit of three common analytical columns, namely a 100 mm x 4.6 mm C18 bonded silica-based monolithic column, a 150 mm x 4.6 mm column packed with 2.7 {micro}m porous shell particles of C18 bonded silica (HALO), and a 150 mm x 4.6 mm column packed with 3 {micro}m fully porous C18 bonded silica particles (LUNA). The results obtained demonstrate that all three columns are not radially homogeneous. In all three cases, the efficiency was found to be lower in the wall region of the column than in its core region (the central core with a radius of 1/3 the column inner radius). The decrease in local efficiency from the core to the wall regions was lower in the case of the monolith (ca. 25%) than in that of the two particle-packed columns (ca. 35-50%). The mobile phase velocity was found to be ca. 1.5% higher in the wall than in the core region of the monolithic column while, in contrast, it was ca. 2.5-4.0% lower in the wall region for the two particle-packed columns.

  3. Modelling of turbulent flow in a radial reactor with fixed bed

    NASA Astrophysics Data System (ADS)

    Zhapbasbayev, U. K.; Ramazanova, G. I.; Kenzhaliev, O. B.

    2015-03-01

    The data of the computation of turbulent flow in the CF- π and CP- π configurations of the radial reactor with a fixed bed are presented. The Reynolds motion equations have been solved jointly with the k- ɛ turbulence model. To couple the parameters of flows at the interface free part-fixed bed the classical continuity equations were used. The computational data are obtained for the averaged and turbulent characteristics, and it is shown that the flow in the fixed bed causes the generation of the turbulence kinetic energy and its dissipation rate; the flow in the CF- π configuration is distributed more uniformly as compared to the CP- π configuration of the radial reactor. Computed data are compared with the experimental ones.

  4. Prediction of heat transfer to a thin liquid film in plane and radially spreading flows

    NASA Technical Reports Server (NTRS)

    Rahman, M. M.; Faghri, A.; Hankey, W. L.; Swanson, T. D.

    1990-01-01

    The energy equation is incorporated in the solution algorithm of Rahman et al. (1990) to compute the heat transfer to a thin film in the presence or absence of gravity. For a plane flow under zero gravity, it is found that, for both isothermal and uniformly heated walls, the heat transfer coefficient gradually decreases downstream, with Nu-asterisk (the Nusselt number in terms of film height) remaining approximately constant except for regions very close to the entrance. In the case of radial flow under zero gravity, Nu-asterisk is found to decrease monotonically when the plane is uniformly heated. Two different flow regimes are identified in the presence of gravity for both plane and radial flows. The results of the study may be applicable to the design of space-based cooling systems.

  5. Solids removal from a coldwater recirculating system - comparison of swirl separator and radial-flow settlers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Solids removal across two settling devices, i.e., a swirl separator and a radial-flow settler, and across a microscreen drum filter was evaluated in a fully recirculating system containing a single 150 m3 'Cornell-type' dual-drain tank during the production of food-size Arctic char and rainbow trout...

  6. Radial Flow Fludized Filter Finds Niche as a Pretreatment System for Surface Water in Small Communities

    EPA Science Inventory

    An emerging technology called radial flow fluidized filter (R3f) has been developed as a low cost simplistic filtration technology for small communities of less than 10,000 people. Fouling is a major impediment to the sustainability of membrane technology particularly for small ...

  7. Response of a radial-bladed centrifugal pump to sinusoidal disturbances for noncavitating flow

    NASA Technical Reports Server (NTRS)

    Anderson, D. A.; Blade, R. J.; Stevans, W.

    1971-01-01

    A radial-bladed centrifugal pump was run in water with sinusoidal fluctuations of pressure and flow rate imposed at the pump inlet. Since the flow was noncavitating, zero gain was assumed in computing pump impedance. The inertive reactance became greater than the resistance at relatively low frequencies. An electric circuit model was developed in order to explain the trends of inertance and resistance with frequency.

  8. Designing and updating the flow part of axial and radial-axial turbines through mathematical modeling

    NASA Astrophysics Data System (ADS)

    Rusanov, Andrey; Rusanov, Roman; Lampart, Piotr

    2015-10-01

    The paper describes an algorithm for the design of axial and radial-axial type turbines. The algorithm is based on using mathematical models of various levels of complexity - from 1D to 3D. Flow path geometry is described by means of analytical methods of profiling using a limited number of parameters. 3D turbulent flow model is realised in the program complex IPMFlow, developed based on the earlier codes FlowER and FlowER-U. Examples of developed or modernized turbines for differentpurpose power machines are presented. They are: an expansion turbine, ORC turbine and cogeneration mediumpressure turbine.

  9. Laminar flow between a stationary and a rotating disk with radial throughflow

    SciTech Connect

    Nesreddine, H.; Nguyen, C.T.; Vo-Ngoc, D.

    1995-05-01

    The problem of axisymmetric laminar flow of a viscous incompressible fluid that occurs between a stationary and a rotating disk subjected to a uniform radial throughflow has been numerically investigated for a large range of flow parameters. Results show that the basic flow structure is rather complex and depends strongly on both the rotational and the flow structure is rather complex and depends strongly on both the rotational and the throughflow Reynolds numbers. In general, the basic unicellular structure has been observed. With the increase of the throughflow Reynolds number, a multicellular flow structure may be found. The phenomenon of multiple solutions has been clearly observed for cases with sufficiently high rational Re and/or high throughflow Re. Among these solutions, stable as well as unstable solutions have been determined by applying Rayleigh`s stability criterion. The influence of the starting conditions on the stability of the flow has also been investigated for various ranges of flow parameters.

  10. Liquid chromatography/Fourier transform IR spectrometry interface flow cell

    DOEpatents

    Johnson, Charles C.; Taylor, Larry T.

    1986-01-01

    A zero dead volume (ZDV) microbore high performance liquid chromatography (.mu.HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a .mu.HPLC column end fitting to minimize the transfer volume of the effluents exiting the .mu.HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF.sub.2), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

  11. Liquid chromatography/Fourier transform IR spectrometry interface flow cell

    DOEpatents

    Johnson, C.C.; Taylor, L.T.

    1985-01-04

    A zero dead volume (ZDV) microbore high performance liquid chromatography (..mu.. HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a ..mu.. HPLC column end fitting to minimize the transfer volume of the effluents exiting the ..mu.. HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF/sub 2/), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

  12. A model of unsteady spatially inhomogeneous flow in a radial-axial blade machine

    NASA Astrophysics Data System (ADS)

    Ambrozhevich, A. V.; Munshtukov, D. A.

    A two-dimensional model of the gasdynamic process in a radial-axial blade machine is proposed which allows for the instantaneous local state of the field of flow parameters, changes in the set angles along the median profile line, profile losses, and centrifugal and Coriolis forces. The model also allows for the injection of cooling air and completion of fuel combustion in the flow. The model is equally applicable to turbines and compressors. The use of the method of singularities provides for a unified and relatively simple description of various factors affecting the flow and, therefore, for computational efficiency.

  13. Simulating MODFLOW-based reactive transport under radially symmetric flow conditions.

    PubMed

    Wallis, Ilka; Prommer, Henning; Post, Vincent; Vandenbohede, Alexander; Simmons, Craig T

    2013-01-01

    Radially symmetric flow and solute transport around point sources and sinks is an important specialized topic of groundwater hydraulics. Analysis of radial flow fields is routinely used to determine heads and flows in the vicinity of point sources or sinks. Increasingly, studies also consider solute transport, biogeochemical processes, and thermal changes that occur in the vicinity of point sources/sinks. Commonly, the analysis of hydraulic processes involves numerical or (semi-) analytical modeling methods. For the description of solute transport, analytical solutions are only available for the most basic transport phenomena. Solving advanced transport problems numerically is often associated with a significant computational burden. However, where axis-symmetry applies, computational cost can be decreased substantially in comparison with full three-dimensional (3D) solutions. In this study, we explore several techniques of simulating conservative and reactive transport within radial flow fields using MODFLOW as the flow simulator, based on its widespread use and ability to be coupled with multiple solute and reactive transport codes of different complexity. The selected transport simulators are MT3DMS and PHT3D. Computational efficiency and accuracy of the approaches are evaluated through comparisons with full 2D/3D model simulations, analytical solutions, and benchmark problems. We demonstrate that radial transport models are capable of accurately reproducing a wide variety of conservative and reactive transport problems provided that an adequate spatial discretization and advection scheme is selected. For the investigated test problems, the computational load was substantially reduced, with the improvement varying, depending on the complexity of the considered reaction network. PMID:22900478

  14. Stability results for multi-layer radial Hele-Shaw and porous media flows

    NASA Astrophysics Data System (ADS)

    Gin, Craig; Daripa, Prabir

    2015-01-01

    Motivated by stability problems arising in the context of chemical enhanced oil recovery, we perform linear stability analysis of Hele-Shaw and porous media flows in radial geometry involving an arbitrary number of immiscible fluids. Key stability results obtained and their relevance to the stabilization of fingering instability are discussed. Some of the key results, among many others, are (i) absolute upper bounds on the growth rate in terms of the problem data; (ii) validation of these upper bound results against exact computation for the case of three-layer flows; (iii) stability enhancing injection policies; (iv) asymptotic limits that reduce these radial flow results to similar results for rectilinear flows; and (v) the stabilizing effect of curvature of the interfaces. Multi-layer radial flows have been found to have the following additional distinguishing features in comparison to rectilinear flows: (i) very long waves, some of which can be physically meaningful, are stable; and (ii) eigenvalues can be complex for some waves depending on the problem data, implying that the dispersion curves for one or more waves can contact each other. Similar to the rectilinear case, these results can be useful in providing insight into the interfacial instability transfer mechanism as the problem data are varied. Moreover, these can be useful in devising smart injection policies as well as controlling the complexity of the long-term dynamics when drops of various immiscible fluids intersperse among each other. As an application of the upper bound results, we provide stabilization criteria and design an almost stable multi-layer system by adding many layers of fluid with small positive jumps in viscosity in the direction of the basic flow.

  15. Radial artery cannulation--the influence of method on blood flow after decannulation.

    PubMed

    Cronin, K D; Davies, M J; Domaingue, C M; Worner, M J; Koumoundouros, E

    1986-11-01

    A prospective randomised study of two hundred patients undergoing open-heart surgery was carried out to determine if the method of radial artery cannulation (direct threading or transfixion) had any influence on the incidence of abnormal flow after decannulation. A standard 20-gauge non-tapered teflon-coated cannula was used and the groups were well matched for age, sex, wrist circumference, duration of cannulation and haematoma formation, all of which have been postulated to influence thrombosis rate. We were unable to demonstrate a statistically significant difference between the two methods of cannulation. The overall abnormal flow rate at five days assessed by Doppler ultrasound was low at 5%. PMID:2952029

  16. Porcine Circovirus (PCV) Removal by Q Sepharose Fast Flow Chromatography

    PubMed Central

    Yang, Bin; Wang, Hua; Ho, Cintia; Lester, Philip; Chen, Qi; Neske, Florian; Baylis, Sally A; Blümel, Johannes

    2013-01-01

    The recently discovered contamination of oral rotavirus vaccines led to exposure of millions of infants to porcine circovirus (PCV). PCV was not detected by conventional virus screening tests. Regulatory agencies expect exclusion of adventitious viruses from biological products. Therefore, methods for inactivation/removal of viruses have to be implemented as an additional safety barrier whenever feasible. However, inactivation or removal of PCV is difficult. PCV is highly resistant to widely used physicochemical inactivation procedures. Circoviruses such as PCV are the smallest viruses known and are not expected to be effectively removed by currently-used virus filters due to the small size of the circovirus particles. Anion exchange chromatography such as Q Sepharose® Fast Flow (QSFF) has been shown to effectively remove a range of viruses including parvoviruses. In this study, we investigated PCV1 removal by virus filtration and by QSFF chromatography. As expected, PCV1 could not be effectively removed by virus filtration. However, PCV1 could be effectively removed by QSFF as used during the purification of monoclonal antibodies (mAbs) and a log10 reduction value (LRV) of 4.12 was obtained. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1464–1471, 2013 PMID:24039195

  17. Laser velocimeter measurements in shrouded and unshrouded radial flow pump impellers

    NASA Technical Reports Server (NTRS)

    Hamkins, C. P.; Flack, R. D.

    1986-01-01

    Shrouded and unshrouded versions of a four-vaned radial flow impeller with a design flow coefficient of 0.063 were tested in a volute pump using a two-component frequency-shifted laser velocimeter. Velocity profiles were measured at six flow rates and at four radial and six circumferential positions in the volute. The variations of the velocity from blade to blade and in the axial direction were measured and are presented. A passage vortex caused by tip leakage and relative casing wall velocity was found in the unshrouded impeller. The tip leakage did not accumulate in the suction wake region; the suction wake region was only 30 to 50 percent as large in the unshrouded impeller as compared to the shrouded impeller. The slip was 30 percent higher in the unshrouded impeller and the variation of slip with flow rate is presented. At no measured position in the impellers did the slip factor reach unity; the closest approach was 0.90. Reverse loadings of the vanes at outer radii were found for flow rates below the impeller/volute matching point for both impellers.

  18. Comparison of the flows and radial electric field in the HSX stellarator to neoclassical calculations

    NASA Astrophysics Data System (ADS)

    Briesemeister, A.; Zhai, K.; Anderson, D. T.; Anderson, F. S. B.; Talmadge, J. N.

    2013-01-01

    Intrinsic flow velocities of up to ˜20 km s-1 have been measured using charge exchange recombination spectroscopy (CHERS) in the quasi-helically symmetric HSX stellarator and are compared with the neoclassical values calculated using an updated version (Lore 2010 Measurement and Transport Modeling with Momentum Conservation of an Electron Internal Transport Barrier in HSX (Madison, WI: University of Wisconsin); Lore et al 2010 Phys. Plasmas 17 056101) of the PENTA code (Spong 2005 Phys. Plasmas. 12 056114). PENTA uses the monoenergetic transport coefficients calculated by the drift kinetic equation solver code (Hirshman et al 1986 Phys. Fluids 29 2951; van Rij and Hirshman 1989 Phys. Fluids B 1 563), but corrects for momentum conservation. In the outer half of the plasma good agreement is seen between the measured parallel flow profile and the calculated neoclassical values when momentum correction is included. The flow velocity in HSX is underpredicted by an order of magnitude when this momentum correction is not applied. The parallel flow is calculated to be approximately equal for the majority hydrogen ions and the C6+ ions used for the CHERS measurements. The pressure gradient of the protons is the primary drive of the calculated parallel flow for a significant portion of the outer half of the plasma. The values of the radial electric field calculated with and without momentum correction were similar, but both were smaller than the measured values in the outer half of the plasma. Differences between the measured and predicted radial electric field are possibly a result of uncertainty in the composition of the ion population and sensitivity of the ion flux calculation to resonances in the radial electric field.

  19. An analysis of the viscous flow through a compact radial turbine by the average passage approach

    NASA Technical Reports Server (NTRS)

    Heidmann, James D.; Beach, Timothy A.

    1990-01-01

    A steady, three-dimensional viscous average passage computer code is used to analyze the flow through a compact radial turbine rotor. The code models the flow as spatially periodic from blade passage to blade passage. Results from the code using varying computational models are compared with each other and with experimental data. These results include blade surface velocities and pressures, exit vorticity and entropy contour plots, shroud pressures, and spanwise exit total temperature, total pressure, and swirl distributions. The three computational models used are inviscid, viscous with no blade clearance, and viscous with blade clearance. It is found that modeling viscous effects improves correlation with experimental data, while modeling hub and tip clearances further improves some comparisons. Experimental results such as a local maximum of exit swirl, reduced exit total pressures at the walls, and exit total temperature magnitudes are explained by interpretation of the flow physics and computed secondary flows. Trends in the computed blade loading diagrams are similarly explained.

  20. Design and flow field calculations for transonic and supersonic radial inflow turbine guide vanes

    SciTech Connect

    Reichert, A.W.; Simon, H.

    1997-01-01

    The design of radial inflow turbine guide vanes depends very much on the discharge conditions desired, especially if the choking mass flow is reached. Because of the choking mass flow condition and supersonic discharge Mach numbers, an inverse design procedure based on the method of characteristics is presented. Various designs corresponding to different discharge Mach numbers are shown. Viscous and inviscid flow field calculations for varying discharge conditions show the properties of the guide vanes at design and off-design conditions. In a previous paper (Reichert and Simon, 1994), an optimized design for transonic discharge conditions has been published. In the present paper, additional results concerning the optimum design are presented. For this optimum design an advantageous adjusting mechanism for a variable geometry guide vane has been developed. The effect of guide vane adjustment on the discharge conditions has been investigated using viscous flow field calculations.

  1. Occurrence of turbulent flow conditions in supercritical fluid chromatography.

    PubMed

    De Pauw, Ruben; Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

    2014-09-26

    Having similar densities as liquids but with viscosities up to 20 times lower (higher diffusion coefficients), supercritical CO2 is the ideal (co-)solvent for fast and/or highly efficient separations without mass-transfer limitations or excessive column pressure drops. Whereas in liquid chromatography the flow remains laminar in both the packed bed and tubing, except in extreme cases (e.g. in a 75 μm tubing, pure acetonitrile at 5 ml/min), a supercritical fluid can experience a transition from laminar to turbulent flow in more typical operation modes. Due to the significant lower viscosity, this transition for example already occurs at 1.3 ml/min for neat CO2 when using connection tubing with an ID of 127 μm. By calculating the Darcy friction factor, which can be plotted versus the Reynolds number in a so-called Moody chart, typically used in fluid dynamics, higher values are found for stainless steel than PEEK tubing, in agreement with their expected higher surface roughness. As a result turbulent effects are more pronounced when using stainless steel tubing. The higher than expected extra-column pressure drop limits the kinetic performance of supercritical fluid chromatography and complicates the optimization of tubing ID, which is based on a trade-off between extra-column band broadening and pressure drop. One of the most important practical consequences is the non-linear increase in extra-column pressure drop over the tubing downstream of the column which leads to an unexpected increase in average column pressure and mobile phase density, and thus decrease in retention. For close eluting components with a significantly different dependence of retention on density, the selectivity can significantly be affected by this increase in average pressure. In addition, the occurrence of turbulent flow is also observed in the detector cell and connection tubing. This results in a noise-increase by a factor of four when going from laminar to turbulent flow (e.g. going

  2. Technique to Measure the Coronal Electron Temperature and Radial Flow Speed

    NASA Astrophysics Data System (ADS)

    Reginald, N. L.; Davila, J. M.; St Cyr, O. C.

    2011-12-01

    During the March 2006 total solar eclipse we conducted an imaging experiment using the Imaging Spectrograph of Coronal Electrons (ISCORE) to determine the coronal electron temperature and its radial flow speed in the low solar corona. This technique required taking images of the solar eclipse through four broadband filters centered at 385.0, 398.7, 410.0 and 423.3 nm. The K-coronal temperature is determined from intensity ratios from the 385.0 and 410.0 nm filters, and the K-coronal radial flow speed is determined from intensity ratios from the 398.7 and 423.3 nm filters. The theoretical model for this technique assumes a symmetric corona devoid of any features like streamers that might alter the coronal symmetry. The model also requires an isothermal temperature and a uniform outflow speed all along the line of sight. We will call this the Constant Parameter Thomson Scattering Model (CPTSM). The latter assumption may sound unreasonable but in the symmetric corona with rapid fall of the electron density with height in the solar corona, the major contributions to the K-coronal intensity along a given line of sight comes from the plasma properties in the vicinity of the plane of the sky. But the pressing question is how is the derived plasma properties by ISCORE compare with the nature of the true corona. For this we turn to the CORHEL model by Predictive Science Inc. which used magnetogram data to create a realistic model of the solar corona that are made available through the Community Coordinated Modeling Center (CCMC) at GSFC. That team has consistently produced the expected coronal image days prior to many total eclipses where the major coronal features from their model matched actual coronal image on the day of the eclipse. Using the CORHEL model data we have calculated the K-coronal intensities at 385.0, 398.7, 410.0 and 423.3 nm using the electron density, plasma temperature (assumed to be electron temperature) and the flow speeds of the plasma along the line

  3. Cyclic and radial variation of ultrasonic backscatter from flowing porcine blood

    NASA Astrophysics Data System (ADS)

    Paeng, Dong-Guk

    The ultrasonic backscattering from flowing blood was investigated using several hemodynamic parameters and a physiological parameter. Acceleration was hypothesized to enhance the aggregation of red blood cells (RBCs), and this is the first time that acceleration is suggested and experimentally verified as having an effect on aggregation of RBC. Two interesting phenomena, the 'Black Hole (BH)' phenomenon and the 'Bright Collapsing Ring (BCR)' phenomenon, were observed under pulsatile flow in B-mode cross sectional images. The BH phenomenon describes a dark hypoechoic hole at the center of the tube surrounded by a bright hyperechoic zone in B-mode cross sectional images, and the BCR phenomenon describes the appearance of a bright hyperechoic ring at the periphery of the tube at early systole and its convergence from the periphery to the center of the tube, finally collapsing as flow develops. Doppler power variation was observed only from porcine whole blood, which led to a conclusion that the ultrasonic backscattering was mainly dependent on the RBC aggregation under steady and pulsatile flow. The pattern of the cyclic variation of the Doppler power to have a maximum power at peak systole was mainly due to the enhanced rouleaux formation by acceleration. The BCR phenomenon was observed from the cyclic variation pattern of the Doppler power at different radial positions; the Doppler power peak was observed at early systole at the periphery of the tube and lagged the flow as close from the periphery to the center of the tube. The BCR phenomenon from porcine whole blood in a mock flow loop was further examined in real time in B-mode images under pulsatile flow. At low hematocrit of 12%, no BCR phenomenon was discernable although it was observed at higher hematocrits. The pattern of the nonlinear relationship between echogenicity and hematocrit varied with radial positions. The BH phenomenon was also observed under certain hemodynamic conditions and varied over a

  4. On the nature of radial transport across sheared zonal flows in electrostatic ion-temperature-gradient gyrokinetic tokamak turbulence

    SciTech Connect

    Sanchez, Raul; Newman, David E; Leboeuf, Jean-Noel; Carreras, Benjamin A; Decyk, Viktor

    2009-01-01

    It is argued that the usual understanding of the suppression of radial turbulent transport across a sheared zonal flow based on a reduction in effective transport coefficients is, by itself, incomplete. By means of toroidal gyrokinetic simulations of electrostatic, ion-temperature-gradient turbulence, it is found instead that the character of the radial transport is altered fundamentally by the presence of a sheared zonal flow, changing from diffusive to anticorrelated and subdiffusive. Furthermore, if the flows are self-consistently driven by the turbulence via the Reynolds stresses (in contrast to being induced externally), radial transport becomes non-Gaussian as well. These results warrant a reevaluation of the traditional description of radial transport across sheared flows in tokamaks via effective transport coefficients, suggesting that such description is oversimplified and poorly captures the underlying dynamics, which may in turn compromise its predictive capabilities.

  5. On the nature of radial transport across sheared zonal flows in electrostatic ion-temperature-gradient gyrokinetic tokamak plasma turbulence

    SciTech Connect

    Sanchez, R.; Newman, D. E.; Leboeuf, J.-N.; Carreras, B. A.; Decyk, V. K.

    2009-05-15

    It is argued that the usual understanding of the suppression of radial turbulent transport across a sheared zonal flow based on a reduction in effective transport coefficients is, by itself, incomplete. By means of toroidal gyrokinetic simulations of electrostatic, ion-temperature-gradient turbulence, it is found instead that the character of the radial transport is altered fundamentally by the presence of a sheared zonal flow, changing from diffusive to anticorrelated and subdiffusive. Furthermore, if the flows are self-consistently driven by the turbulence via the Reynolds stresses (in contrast to being induced externally), radial transport becomes non-Gaussian as well. These results warrant a reevaluation of the traditional description of radial transport across sheared flows in tokamaks via effective transport coefficients, suggesting that such description is oversimplified and poorly captures the underlying dynamics, which may in turn compromise its predictive capabilities.

  6. Direct numerical simulation of Taylor-Couette flow subjected to a radial temperature gradient

    NASA Astrophysics Data System (ADS)

    Teng, Hao; Liu, Nansheng; Lu, Xiyun; Khomami, Bamin

    2015-12-01

    Direct numerical simulations have been performed to study the Taylor-Couette (TC) flow between two rotating, coaxial cylinders in the presence of a radial temperature gradient. Specifically, the influence of the buoyant force and the outer cylinder rotation on the turbulent TC flow system with the radius ratio η = 0.912 was examined. For the co-rotating TC flows with Rei (inner cylinder) =1000 and Reo (outer cylinder) =100, a transition pathway to highly turbulent flows is realized by increasing σ, a parameter signifying the ratio of buoyant to inertial force. This nonlinear flow transition involves four intriguing states that emerge in sequence as chaotic wavy vortex flow for σ = 0, wavy interpenetrating spiral flows for σ = 0.02 and 0.05, intermittent turbulent spirals for σ = 0.1 and 0.2, and turbulent spirals for σ = 0.4. Overall, the fluid motion changes from a centrifugally driven flow regime characterized by large-scale wavy Taylor vortices (TVs) to a buoyancy-dominated flow regime characterized by small-scale turbulent vortices. Commensurate changes in turbulence statistics and heat transfer are seen as a result of the weakening of large-scale TV circulations and enhancement of turbulent motions. Additionally, the influence of variation of the outer cylinder rotation, -500 < Reo < 500 in presence of buoyancy (σ = 0.1) with Rei = 1000, has been considered. Specifically, it is demonstrated that this variation strongly influences the azimuthal and axial mean flows with a weaker influence on the fluctuating fluid motions. Of special interest, here are the turbulent dynamics near the outer wall where a marked decrease of turbulence intensity and a sign inversion of the Reynolds stress Rrz are observed for the strongly counter-rotating regimes (Reo = - 300 and -500). To this end, it has been shown that the underlying flow physics for this drastic modification are associated with the modification of the correlation between the radial and axial fluctuating

  7. Direct numerical simulation of Taylor-Couette flow subjected to a radial temperature gradient

    SciTech Connect

    Teng, Hao; Liu, Nansheng Lu, Xiyun; Khomami, Bamin

    2015-12-15

    Direct numerical simulations have been performed to study the Taylor-Couette (TC) flow between two rotating, coaxial cylinders in the presence of a radial temperature gradient. Specifically, the influence of the buoyant force and the outer cylinder rotation on the turbulent TC flow system with the radius ratio η = 0.912 was examined. For the co-rotating TC flows with Re{sub i} (inner cylinder) =1000 and Re{sub o} (outer cylinder) =100, a transition pathway to highly turbulent flows is realized by increasing σ, a parameter signifying the ratio of buoyant to inertial force. This nonlinear flow transition involves four intriguing states that emerge in sequence as chaotic wavy vortex flow for σ = 0, wavy interpenetrating spiral flows for σ = 0.02 and 0.05, intermittent turbulent spirals for σ = 0.1 and 0.2, and turbulent spirals for σ = 0.4. Overall, the fluid motion changes from a centrifugally driven flow regime characterized by large-scale wavy Taylor vortices (TVs) to a buoyancy-dominated flow regime characterized by small-scale turbulent vortices. Commensurate changes in turbulence statistics and heat transfer are seen as a result of the weakening of large-scale TV circulations and enhancement of turbulent motions. Additionally, the influence of variation of the outer cylinder rotation, −500 < Re{sub o} < 500 in presence of buoyancy (σ = 0.1) with Re{sub i} = 1000, has been considered. Specifically, it is demonstrated that this variation strongly influences the azimuthal and axial mean flows with a weaker influence on the fluctuating fluid motions. Of special interest, here are the turbulent dynamics near the outer wall where a marked decrease of turbulence intensity and a sign inversion of the Reynolds stress R{sub rz} are observed for the strongly counter-rotating regimes (Re{sub o} = − 300 and −500). To this end, it has been shown that the underlying flow physics for this drastic modification are associated with the modification of the correlation

  8. Chromatography

    MedlinePlus

    Chromatography is a way of separating two or more chemical compounds. Chemical compounds are chemicals that are ... of chemical compound. There are different kinds of chromatography. These include gas, high pressure liquid, or ion ...

  9. Application of radial-equilibrium condition to axial-flow compressor and turbine design

    NASA Technical Reports Server (NTRS)

    Wu, Chung-Hua; Wolfenstein, Lincoln

    1950-01-01

    Basic general equations governing the three-dimensional compressible flow of gas through a compressor or turbine are given in terms of total enthalpy, entropy, and velocity components of the gas. Two methods of solution are obtained for the simplified, steady axially symmetric flow; one involves the use of a number of successive planes normal to the axis of the machine and short distances apart, and the other involves only three stations for a stage in which an appropriate radial-flow path is used. Methods of calculation for the limiting cases of zero and infinite blade aspect ratios and an approximate method of calculation for finite blade aspect ratio are also given. In these methods, the blade loading and the shape of the annular passage wall may be arbitrarily specified.

  10. 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.

  11. An analytical solution for transient radial flow through unsaturated fractured porous media

    SciTech Connect

    Wu, Yu-Shu; Pan, Lehua

    2004-02-13

    This paper presents analytical solutions for one-dimensional radial transient flow through horizontal, unsaturated fractured rock formation. In these solutions, unsaturated flow through fractured media is described by a linearized Richards' equation, while fracture-matrix interaction is handled using the dual-continuum concept. Although linearizing Richards' equation requires a specially correlated relationship between relative permeability and capillary pressure functions for both fractures and matrix, these specially formed relative permeability and capillary pressure functions are still physically meaningful. These analytical solutions can thus be used to describe the transient behavior of unsaturated flow in fractured media under the described model conditions. They can also be useful in verifying numerical simulation results, which, as demonstrated in this paper, are otherwise difficult to validate.

  12. Estimating vertical velocity and radial flow from Doppler radar observations of tropical cyclones

    NASA Astrophysics Data System (ADS)

    Lee, J. L.; Lee, W. C.; MacDonald, A. E.

    2006-01-01

    The mesoscale vorticity method (MVM) is used in conjunction with the ground-based velocity track display (GBVTD) to derive the inner-core vertical velocity from Doppler radar observations of tropical cyclone (TC) Danny (1997). MVM derives the vertical velocity from vorticity variations in space and in time based on the mesoscale vorticity equation. The use of MVM and GBVTD allows us to derive good correlations among the eye-wall maximum wind, bow-shaped updraught and echo east of the eye-wall in Danny. Furthermore, we demonstrate the dynamically consistent radial flow can be derived from the vertical velocity obtained from MVM using the wind decomposition technique that solves the Poisson equations over a limited-area domain. With the wind decomposition, we combine the rotational wind which is obtained from Doppler radar wind observations and the divergent wind which is inferred dynamically from the rotational wind to form the balanced horizontal wind in TC inner cores, where rotational wind dominates the divergent wind. In this study, we show a realistic horizontal and vertical structure of the vertical velocity and the induced radial flow in Danny's inner core. In the horizontal, the main eye-wall updraught draws in significant surrounding air, converging at the strongest echo where the maximum updraught is located. In the vertical, the main updraught tilts vertically outwards, corresponding very well with the outward-tilting eye-wall. The maximum updraught is located at the inner edge of the eye-wall clouds, while downward motions are found at the outer edge. This study demonstrates that the mesoscale vorticity method can use high-temporal-resolution data observed by Doppler radars to derive realistic vertical velocity and the radial flow of TCs. The vorticity temporal variations crucial to the accuracy of the vorticity method have to be derived from a high-temporal-frequency observing system such as state-of-the-art Doppler radars.

  13. Why is the radial flow in central pA collisions stronger than in AA?

    NASA Astrophysics Data System (ADS)

    Kalaydzhyan, Tigran; Shuryak, Edward

    2014-11-01

    Both the transverse size and entropy density per area in central pA collisions is smaller than in central AA, and yet the radial flow is stronger. We propose an explanation to this puzzle. Using a weak attraction between strings through the σ-meson exchange, fitted to the lattice data, we find collective implosion of the "spaghetti" multi-string state. Collectivization of the sigma field of the strings is the QCD analog of the black hole formation occurring in holographic models.

  14. Radial flow fuel nozzle for a combustor of a gas turbine

    DOEpatents

    Means, Gregory Scott; Boardman, Gregory Allen; Berry, Jonathan Dwight

    2016-07-05

    A combustor for a gas turbine generally includes a radial flow fuel nozzle having a fuel distribution manifold, and a fuel injection manifold axially separated from the fuel distribution manifold. The fuel injection manifold generally includes an inner side portion, an outer side portion, and a plurality of circumferentially spaced fuel ports that extend through the outer side portion. A plurality of tubes provides axial separation between the fuel distribution manifold and the fuel injection manifold. Each tube defines a fluid communication path between the fuel distribution manifold and the fuel injection manifold.

  15. Proton/pion ratios and radial flow in pp and peripheral heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Cuautle, E.; Paić, G.

    2006-09-01

    The production of baryon and mesons in the RHIC heavy-ion experiments has received a lot of attention lately. Although not widely known, the pp data measured concurrently with heavy ion collisions do not find a convincing explanation in terms of simple models. We present the results of an afterburner to Pythia and Hijing event generators, simulating radial flow which seems to qualitatively explain the experimental results when applied to the pp collision data from RHIC at 200 GeV center-of-mass energy.

  16. Proton/pion ratios and radial flow in pp and peripheral heavy ion collisions

    SciTech Connect

    Cuautle, E.; Paic, G.

    2006-09-25

    The production of baryon and mesons in the RHIC heavy-ion experiments has received a lot of attention lately. Although not widely known, the pp data measured concurrently with heavy ion collisions do not find a convincing explanation in terms of simple models. We present the results of an afterburner to Pythia and Hijing event generators, simulating radial flow which seems to qualitatively explain the experimental results when applied to the pp collision data from RHIC at 200 GeV center-of-mass energy.

  17. Flow mechanism of Forchheimer's cubic equation in high-velocity radial gas flow through porous media

    SciTech Connect

    Ezeudembah, A.S.; Dranchuk, P.M.

    1982-01-01

    Formal derivation of Forchheimer's cubic equation is made by considering the kinetic energy equation of mean flow and dimensional relations for one-dimensional, linear, incompressible fluid flow. By the addition of the cubic term, this equation is regarded as a modified Forchheimer's quadratic equation which accounts for the flow rates obtained beyond the laminar flow condition. The cubic equation spans a wide range of flow rates and regimes. For suitable use in gas flow studies, this equation has been adapted, modified, and corrected for the gas slippage effect. The physical basis of the cubic term has been established by using boundary layer theory to explain the high-velocity, high-pressure flow behavior through a porous path. Gamma, the main parameter in the cubic term, is related directly to a characteristic, dimensionless shape factor which is significant at higher flow rates. It is inversely related to viscosity, but has no dependence on the gas slippage coefficient in the higher flow regime. 25 references.

  18. Eigenmodes of Ducted Flows With Radially-Dependent Axial and Swirl Velocity Components

    NASA Technical Reports Server (NTRS)

    Kousen, Kenneth A.

    1999-01-01

    This report characterizes the sets of small disturbances possible in cylindrical and annular ducts with mean flow whose axial and tangential components vary arbitrarily with radius. The linearized equations of motion are presented and discussed, and then exponential forms for the axial, circumferential, and time dependencies of any unsteady disturbances are assumed. The resultant equations form a generalized eigenvalue problem, the solution of which yields the axial wavenumbers and radial mode shapes of the unsteady disturbances. Two numerical discretizations are applied to the system of equations: (1) a spectral collocation technique based on Chebyshev polynomial expansions on the Gauss-Lobatto points, and (2) second and fourth order finite differences on uniform grids. The discretized equations are solved using a standard eigensystem package employing the QR algorithm. The eigenvalues fall into two primary categories: a discrete set (analogous to the acoustic modes found in uniform mean flows) and a continuous band (analogous to convected disturbances in uniform mean flows) where the phase velocities of the disturbances correspond to the local mean flow velocities. Sample mode shapes and eigensystem distributions are presented for both sheared axial and swirling flows. The physics of swirling flows is examined with reference to hydrodynamic stability and completeness of the eigensystem expansions. The effect of assuming exponential dependence in the axial direction is discussed.

  19. Effect of Radial Density Configuration on Wave Field and Energy Flow in Axially Uniform Helicon Plasma

    NASA Astrophysics Data System (ADS)

    Chang, Lei; Li, Qingchong; Zhang, Huijie; Li, Yinghong; Wu, Yun; Zhang, Bailing; Zhuang, Zhong

    2016-08-01

    The effect of the radial density configuration in terms of width, edge gradient and volume gradient on the wave field and energy flow in an axially uniform helicon plasma is studied in detail. A three-parameter function is employed to describe the density, covering uniform, parabolic, linear and Gaussian profiles. It finds that the fraction of power deposition near the plasma edge increases with density width and edge gradient, and decays in exponential and “bump-on-tail” profiles, respectively, away from the surface. The existence of a positive second-order derivative in the volume density configuration promotes the power deposition near the plasma core, which to our best knowledge has not been pointed out before. The transverse structures of wave field and current density remain almost the same during the variation of density width and gradient, confirming the robustness of the m=1 mode observed previously. However, the structure of the electric wave field changes significantly from a uniform density configuration, for which the coupling between the Trivelpiece-Gould (TG) mode and the helicon mode is very strong, to non-uniform ones. The energy flow in the cross section of helicon plasma is presented for the first time, and behaves sensitive to the density width and edge gradient but insensitive to the volume gradient. Interestingly, the radial distribution of power deposition resembles the radial profile of the axial component of current density, suggesting the control of the power deposition profile in the experiment by particularly designing the antenna geometry to excite a required axial current distribution. supported by National Natural Science Foundation of China (No. 11405271)

  20. A PC-based inverse design method for radial and mixed flow turbomachinery

    NASA Technical Reports Server (NTRS)

    Skoe, Ivar Helge

    1991-01-01

    An Inverse Design Method suitable for radial and mixed flow turbomachinery is presented. The codes are based on the streamline curvature concept; therefore, it is applicable for current personal computers from the 286/287 range. In addition to the imposed aerodynamic constraints, mechanical constraints are imposed during the design process to ensure that the resulting geometry satisfies production consideration and that structural considerations are taken into account. By the use of Bezier Curves in the geometric modeling, the same subroutine is used to prepare input for both aero and structural files since it is important to ensure that the geometric data is identical to both structural analysis and production. To illustrate the method, a mixed flow turbine design is shown.

  1. Evidence for Radial Flow of Thermal Dileptons in High-Energy Nuclear Collisions

    SciTech Connect

    Arnaldi, R.; Colla, A.; Cortese, P.; Ferretti, A.; Oppedisano, C.; Scomparin, E.; Banicz, K.; Damjanovic, S.; Castor, J.; Devaux, A.; Fargeix, J.; Force, P.; Manso, F.; Chaurand, B.; Cicalo, C.; Falco, A. de; Floris, M.; Masoni, A.; Puddu, G.; Serci, S.

    2008-01-18

    The NA60 experiment at the CERN SPS has studied low-mass dimuon production in 158A GeV In-In collisions. An excess of pairs above the known meson decays has been reported before. We now present precision results on the associated transverse momentum spectra. The slope parameter T{sub eff} extracted from the spectra rises with dimuon mass up to the {rho}, followed by a sudden decline above. While the initial rise is consistent with the expectations for radial flow of a hadronic decay source, the decline signals a transition to an emission source with much smaller flow. This may well represent the first direct evidence for thermal radiation of partonic origin in nuclear collisions.

  2. Radially dependent large-scale dynamos in global cylindrical shear flows and the local cartesian limit

    NASA Astrophysics Data System (ADS)

    Ebrahimi, F.; Blackman, E. G.

    2016-06-01

    For cylindrical differentially rotating plasmas, we study large-scale magnetic field generation from finite amplitude non-axisymmetric perturbations by comparing numerical simulations with quasi-linear analytic theory. When initiated with a vertical magnetic field of either zero or finite net flux, our global cylindrical simulations exhibit the magnetorotational instability (MRI) and large-scale dynamo growth of radially alternating mean fields, averaged over height and azimuth. This dynamo growth is explained by our analytic calculations of a non-axisymmetric fluctuation-induced electromotive force that is sustained by azimuthal shear of the fluctuating fields. The standard `Ω effect' (shear of the mean field by differential rotation) is unimportant. For the MRI case, we express the large-scale dynamo field as a function of differential rotation. The resulting radially alternating large-scale fields may have implications for angular momentum transport in discs and corona. To connect with previous work on large-scale dynamos with local linear shear and identify the minimum conditions needed for large-scale field growth, we also solve our equations in local Cartesian coordinates. We find that large-scale dynamo growth in a linear shear flow without rotation can be sustained by shear plus non-axisymmetric fluctuations - even if not helical, a seemingly previously unidentified distinction. The linear shear flow dynamo emerges as a more restricted version of our more general new global cylindrical calculations.

  3. Flow regimes in a vertical Taylor-Couette system with a radial thermal gradient

    NASA Astrophysics Data System (ADS)

    Guillerm, R.; Kang, C.; Savaro, C.; Lepiller, V.; Prigent, A.; Yang, K.-S.; Mutabazi, I.

    2015-09-01

    A rich variety of flow regimes in a Newtonian fluid inside a vertical large-aspect ratio and a wide-gap Taylor-Couette system with a radial temperature gradient has been determined in experiments and in direct numerical simulations (DNSs). Compared to previous experiments and numerical studies, a wider range of temperature differences (i.e., of the Grashof number Gr) and of the rotation rate (the Taylor number Ta) has been covered. The combined effect of rotation and of the radial temperature gradient is the occurrence of helicoidal vortices or modulated waves at the onset. Stationary axisymmetric vortices are found for very weak temperature differences. A good agreement was found for critical states between results from experiments, linear stability analysis, and DNS. Higher instability modes have been determined for a wide range of parameters and a state diagram of observable flow regimes has been established in the plane spanned by Gr and Ta. Some higher states observed in experiments were retrieved in DNS.

  4. Width and rugosity of the topological plasma flow structures and their relation to the radial flights of particle tracers

    NASA Astrophysics Data System (ADS)

    García, L.; Llerena Rodríguez, I.; Carreras, B. A.

    2015-09-01

    An analysis of the distributions of the width and rugosity of topological plasma flow structures is presented for some resistive pressure-gradient-driven turbulence results. The distributions of the radial excursions of particle tracers during trappings are compared with those of the width and rugosity of the flow structures.

  5. Red blood cells radial dispersion in blood flowing through microchannels: The role of temperature.

    PubMed

    Pinho, Diana; Rodrigues, Raquel O; Faustino, Vera; Yaginuma, Tomoko; Exposto, José; Lima, Rui

    2016-07-26

    The behavior of suspensions of individual blood cells, such as red blood cells (RBCs), flowing through microvessels and microfluidic systems depend strongly on the hematocrit (Hct), microvessel topology and cell properties. Although it is well known that blood rheological properties are temperature dependent, to the best of our knowledge no work has studied the role of the temperature on the RBCs dispersion. A powerful way to investigate this latter effect is through a high-speed video microscopy system, which provides detailed flow measurements of each individual RBC. Hence, the effect of temperature on the RBCs dispersion flowing through a 100μm glass capillary was examined by means of a confocal micro-PTV system. Hundreds of labeled RBCs were tracked at moderate Hct (12%) and at four different temperatures, i.e., 25°C, 32°C, 37°C and 42°C. The results yielded an enhancement of the RBCs diffusion as the temperature increases. Hence, our findings show that RBCs radial dispersion is temperature dependent and as a result the temperature should not be ignored in future blood flow studies. We believe that this finding is important for a better understanding of blood mass transport mechanisms under both physiological and pathological conditions. PMID:26671221

  6. An interactive grid generation procedure for axial and radial flow turbomachinery

    NASA Astrophysics Data System (ADS)

    Beach, T. A.

    1990-01-01

    A combination algebraic/elliptic technique is presented for the generation of three dimensional grids about turbo-machinery blade rows for both axial and radial flow machinery. The technique is built around use of an advanced engineering workstation to construct several two dimensional grids interactively on predetermined blade-to-blade surfaces. A three dimensional grid is generated by interpolating these surface grids onto an axisymmetric grid. On each blade-to-blade surface, a grid is created using algebraic techniques near the blade to control orthogonality within the boundary layer region and elliptic techniques in the mid-passage to achieve smoothness. The interactive definition of bezier curves as internal boundaries is the key to simple construction. This procedure lends itself well to zonal grid construction, an important example being the tip clearance region. Calculations done to date include a space shuttle main engine turbopump blade, a radial inflow turbine blade, and the first stator of the United Technologies Research Center large scale rotating rig. A finite Navier-Stokes solver was used in each case.

  7. An interactive grid generation procedure for axial and radial flow turbomachinery

    NASA Technical Reports Server (NTRS)

    Beach, Timothy A.

    1989-01-01

    A combination algebraic/elliptic technique is presented for the generation of three dimensional grids about turbo-machinery blade rows for both axial and radial flow machinery. The technique is built around use of an advanced engineering workstation to construct several two dimensional grids interactively on predetermined blade-to-blade surfaces. A three dimensional grid is generated by interpolating these surface grids onto an axisymmetric grid. On each blade-to-blade surface, a grid is created using algebraic techniques near the blade to control orthogonality within the boundary layer region and elliptic techniques in the mid-passage to achieve smoothness. The interactive definition of bezier curves as internal boundaries is the key to simple construction. This procedure lends itself well to zonal grid construction, an important example being the tip clearance region. Calculations done to date include a space shuttle main engine turbopump blade, a radial inflow turbine blade, and the first stator of the United Technologies Research Center large scale rotating rig. A finite Navier-Stokes solver was used in each case.

  8. Radial-radial single rotor turbine

    DOEpatents

    Platts, David A.

    2006-05-16

    A rotor for use in turbine applications has a radial compressor/pump having radially disposed spaced apart fins forming passages and a radial turbine having hollow turbine blades interleaved with the fins and through which fluid from the radial compressor/pump flows. The rotor can, in some applications, be used to produce electrical power.

  9. Three-dimensional flow in radial turbomachinery and its impact on design

    NASA Technical Reports Server (NTRS)

    Tan, Choon S.; Hawthorne, William

    1993-01-01

    In the two papers on the 'Theory of Blade Design for Large Deflections' published in 1984, a new inverse design technique was presented for designing the shape of turbomachinery blades in three-dimensional flow. The technique involves the determination of the blade profile from the specification of a distribution of the product of the radius and the pitched averaged tangential velocity (i.e., r bar-V(sub theta), the mean swirl schedule) within the bladed region. This is in contrast to the conventional inverse design technique for turbomachinery blading in two dimensional flow in which the blade surface pressure or velocity distribution is specified and the blade profile determined as a result; this is feasible in two-dimensional flow because the streamlines along the blade surfaces are known a priori. However, in three-dimensional flow, the stream surface is free to deform within the blade passage so that the streamlines on the blade surfaces are not known a priori; thus it is difficult and not so useful to prescribe the blade surface pressure or velocity distribution and determine the resulting blade profile. It therefore seems logical to prescribe the swirl schedule within the bladed region for designing a turbomachinery blade profile in three-dimensional flow. Furthermore, specifying r bar-V(sub theta) has the following advantages: (1) it is related to the circulation around the blade (i.e., it is an aerodynamic quantity); (2) the work done or extracted is approximately proportional to the overall change in r bar-V(sub theta) across a given blade row (Euler turbine equation); and (3) the rate of change of r bar-V(sub theta) along the mean streamline at the blade is related to the pressure jump across the blade and therefore the blade loading. Since the publications of those two papers, the technique has been applied to the design of a low speed as well as a high speed radial inflow turbine (for turbocharger applications) both of which showed definite

  10. Comparisons between seismic Earth structures and mantle flow models based on radial correlation functions.

    PubMed

    Jordan, T H; Puster, P; Glatzmaier, G A; Tackley, P J

    1993-09-10

    Three-dimensional numerical simulations were conducted of mantle convection in which flow through the transition zone is impeded by either a strong chemical change or an endothermic phase change. The temperature fields obtained from these models display a well-defined minimum in the vertical correlation length at or near the radius where the barrier is imposed, even when the fields were filtered to low angular and radial resolutions. However, evidence for such a feature is lacking in the shear-velocity models derived by seismic tomography. This comparison suggests that any stratification induced by phase or chemical changes across the mid-mantle transition zone has a relatively small effect on the large-scale circulation of mantle material. PMID:17745353

  11. Accurate evaluation of viscoelasticity of radial artery wall during flow-mediated dilation in ultrasound measurement

    NASA Astrophysics Data System (ADS)

    Sakai, Yasumasa; Taki, Hirofumi; Kanai, Hiroshi

    2016-07-01

    In our previous study, the viscoelasticity of the radial artery wall was estimated to diagnose endothelial dysfunction using a high-frequency (22 MHz) ultrasound device. In the present study, we employed a commercial ultrasound device (7.5 MHz) and estimated the viscoelasticity using arterial pressure and diameter, both of which were measured at the same position. In a phantom experiment, the proposed method successfully estimated the elasticity and viscosity of the phantom with errors of 1.8 and 30.3%, respectively. In an in vivo measurement, the transient change in the viscoelasticity was measured for three healthy subjects during flow-mediated dilation (FMD). The proposed method revealed the softening of the arterial wall originating from the FMD reaction within 100 s after avascularization. These results indicate the high performance of the proposed method in evaluating vascular endothelial function just after avascularization, where the function is difficult to be estimated by a conventional FMD measurement.

  12. Estimated Performance of Radial-Flow Exit Nozzles for Air in Chemical Equilibrium

    NASA Technical Reports Server (NTRS)

    Englert, Gerald W.; Kochendorfer, Fred D.

    1959-01-01

    The thrust, boundary-layer, and heat-transfer characteristics were computed for nozzles having radial flow in the divergent part. The working medium was air in chemical equilibrium, and the boundary layer was assumed to be all turbulent. Stagnation pressure was varied from 1 to 32 atmospheres, stagnation temperature from 1000 to 6000 R, and wall temperature from 1000 to 3000 R. Design pressure ratio was varied from 5 to 320, and operating pressure ratio was varied from 0.25 to 8 times the design pressure ratio. Results were generalized independent of divergence angle and were also generalized independent of stagnation pressure in the temperature range of 1000 to 3000 R. A means of determining the aerodynamically optimum wall angle is provided.

  13. Evaluating the Uncertainty of Regional Flow by Using Radial Basis Function Network and Bootstrap Methods

    NASA Astrophysics Data System (ADS)

    Kan, P.

    2011-12-01

    This study employs radial basis function network (RBFNN) to simulate regional runoff in the future climate condition in Taiwan and bootstrap sampling technique to evaluate uncertainties of RBFNN. The hydrological and meteorological data (such as rainfall, river flow) in northern area of Taiwan during 1981 to 1999 are adopted as the training dataset to RBFNN, in which the parameters of RBFNN are optimized with genetic algorithm (GA). Meanwhile, the bootstrap sampling technique is applied for uncertainty analysis of RBFNN. The simulated results show that RBFNN with GA simulating the regional runoff reveals good performance and corresponding uncertainty can be evaluated by the bootstrap sampling technique. The results also illustrate that selecting training datasets randomly and repeatedly can reduce the possibility of model over-fitting of RBFNN. The regional runoff in the future can be estimated into an interval representing the possibility of the runoff by the proposed approach.

  14. Experiments on Thermal Convection in Rotating Spherical Shells With Radial Gravity: The Geophysical Fluid Flow Cell

    NASA Technical Reports Server (NTRS)

    Hart, John E.

    1996-01-01

    Experiments designed to study the fluid dynamics of buoyancy driven circulations in rotating spherical shells were conducted on the United States Microgravity Laboratory 2 spacelab mission. These experiments address several aspects of prototypical global convection relevant to large scale motions on the Sun, Earth, and on the giant planets. The key feature is the consistent modeling of radially directed gravity in spherical geometry by using dielectric polarization forces. Imagery of the planforms of thermally driven flows for rapidly-rotating regimes shows an initial separation and eventual merger of equatorial and polar convection as the heating (i.e. the Rayleigh number) is increased. At low rotation rates, multiple-states of motion for the same external parameters were observed.

  15. Performance back-deduction from a loading to flow coefficient map: Application to radial turbine

    NASA Astrophysics Data System (ADS)

    Carbonneau, Xavier; Binder, Nicolas

    2012-12-01

    Radial turbine stages are often used for applications requiring off-design operation, as turbocharging for instance. The off-design ability of such stages is commonly analyzed through the traditional turbine map, plotting the reduced mass-flow against the pressure-ratio, for reduced-speed lines. However, some alternatives are possible, such as the flow-coefficient ( Ψ) to loading-coefficient ( φ) diagram where the pressure-ratio lines are actually straight lines, very convenient property to perform prediction. A robust method re-creating this map from a predicted Ψ-φ diagram is needed. Recent work has shown that this back-deduction quality, without the use of any loss models, depends on the knowledge of an intermediate pressure-ratio. A modelization of this parameter is then proposed. The comparison with both experimental and CFD results is presented, with quite good agreement for mass flow rate and rotational speed, and for the intermediate pressure ratio. The last part of the paper is dedicated to the application of the intermediate pressure-ratio knowledge to the improvement of the deduction of the pressure ratio lines in the Ψ-φ diagram. Beside this improvement, the back-deduction method of the classical map is structured, applied and evaluated.

  16. Aerodynamic design of turbomachinery blading in three-dimensional flow - An application to radial inflow turbines

    NASA Technical Reports Server (NTRS)

    Yang, Y. L.; Tan, C. S.; Hawthorne, W. R.

    1992-01-01

    A computational method, based on a theory for turbomachinery blading design in three-dimensional inviscid flow, is applied to a parametric design study of a radial inflow turbine wheel. As the method requires the specification of swirl distribution, a technique for its smooth generation within the blade region is proposed. Excellent agreements have been obtained between the computed results from this design method and those from direct Euler computations, demonstrating the correspondence and consistency between the two. The computed results indicate the sensitivity of the pressure distribution to a lean in the stacking axis and a minor alteration in the hub/shroud profiles. Analysis based on Navier-Stokes solver shows no breakdown of flow within the designed blade passage and agreement with that from design calculation; thus the flow in the designed turbine rotor closely approximates that of an inviscid one. These calculations illustrate the use of a design method coupled to an analysis tool for establishing guidelines and criteria for designing turbomachinery blading.

  17. PIV investigation of the flow induced by a passive surge control method in a radial compressor

    NASA Astrophysics Data System (ADS)

    Guillou, Erwann; Gancedo, Matthieu; Gutmark, Ephraim; Mohamed, Ashraf

    2012-09-01

    Due to recent emission regulations, the use of turbochargers for force induction of internal combustion engines has increased. Actually, the trend in diesel engines is to downsize the engine by use of turbochargers that operate at higher pressure ratios. Unfortunately, increasing the impeller rotational speed of turbocharger radial compressors tends to reduce their range of operation, which is limited at low mass flow rate by the occurrence of surge. In order to extend the operability of turbochargers, compressor housings can be equipped with a passive surge control device such as a "ported shroud." This specific casing treatment has been demonstrated to enhance the surge margin with minor negative impact on the compressor efficiency. However, the actual working mechanisms of the system remain not well understood. Hence, in order to optimize the design of the ported shroud, it is crucial to identify the dynamic flow changes induced by the implementation of the device to control instabilities. From the full dynamic survey of the compressor performance characteristics obtained with and without ported shroud, specific points of operation were selected to carry out planar flow visualization. At normal working, both standard and stereoscopic particle imaging velocimetry (PIV) measurements were performed to evaluate instantaneous and mean velocity flow fields at the inlet of the compressor. At incipient and full surge, phase-locked PIV measurements were added. As a result, satisfying characterization of the compressor instabilities was provided at different operational speeds. Combining transient pressure data and PIV measurements, the time evolution of the complex flow patterns occurring at surge was reconstructed and a better insight into the bypass mechanism was achieved.

  18. Chromatography

    MedlinePlus

    ... a way of separating two or more chemical compounds. Chemical compounds are chemicals that are bonded together. For example, ... and hydrogen. Proteins are another type of chemical compound. There are different kinds of chromatography. These include ...

  19. Axial development and radial non-uniformity of flow in packed columns.

    PubMed

    Park, Jaekeun C; Raghavan, Karthik; Gibbs, Stephen J

    2002-02-01

    Flow inhomogeneity and axial development in low-pressure chromatographic columns have been studied by magnetic resonance imaging velocimetry. The columns studied included (a) an 11.7-mm I.D. column packed with either 50 microm diameter porous polyacrylamide, or 99 or 780 microm diameter impermeable polystyrene beads, and (b) a 5-mm I.D. column commercially packed with 10 microm polymeric beads. The packing methods included gravity settling, slurry packing, ultrasonication, and dry packing with vibration. The magnetic resonance method used averaged apparent fluid velocity over both column cross-sections and fluid displacements greater than one particle diameter and hence permits assessment of macroscopic flow non-uniformities. The results confirm that now non-uniformities induced by the conical distributor of the 11.7-mm I.D. column or the presence of voids at the column entrance relax on a length scale of the column radius. All of the 11.7-mm I.D. columns examined exhibit near wall channeling within a few particle diameters of the wall. The origins of this behavior are demonstrated by imaging of the radial dependence of the local porosity for a column packed with 780 microm beads. Columns packed with the 99-microm beads exhibit reduced flow in a region extending from ten to three-to-five particle diameters from the wall. This velocity reduction is consistent with a reduced porosity of 0.35 in this region as compared to approximately 0.43 in the bulk of the column. Ultrasonicated and dry-packed columns exhibit enhanced flow in a region located between approximately eight and 20 particle diameters from the wall. This enhancement maybe caused by packing density inhomogeneity and/or particle size segregation caused by vibration during the packing process. No significant non-uniformities on length scales of 20 microm or greater were observed in the commercially packed column packed with 10 microm particles. PMID:11860146

  20. Travel time approach to kinetically sorbing solute by diverging radial flows through heterogeneous porous formations

    NASA Astrophysics Data System (ADS)

    Severino, Gerardo; de Bartolo, Samuele; Toraldo, Gerardo; Srinivasan, Gowri; Viswanathan, Hari

    2012-12-01

    Diverging radial flow takes place in a heterogeneous porous medium where the log conductivity Y = ln K is modeled as a stationary random space function (RSF). The flow is steady, and is generated by a fully penetrating well. A linearly sorbing solute is injected through the well envelope, and we aim at computing the average flux concentration (breakthrough curve). A relatively simple solution for this difficult problem is achieved by adopting, similar to Indelman and Dagan (1999), a few simplifying assumptions: (i) a thick aquifer of large horizontal extent, (ii) mildly heterogeneous medium, (iii) strongly anisotropic formation, and (iv) large Peclet number. By introducing an appropriate Lagrangian framework, three-dimensional transport is mapped onto a one-dimensional domain (τ, t) where τ and t represent the fluid travel and current time, respectively. Central for this approach is the probability density function of the RSF τthat is derived consistently with the adopted assumptions stated above. Based on this, it is shown that the travel time can be regarded as a Gaussian random variable only in the far field. The breakthrough curves are analyzed to assess the impact of the hydraulic as well as reactive parameters. Finally, the travel time approach is tested against a forced-gradient transport experiment and shows good agreement.

  1. The Potential Effects of a Biofeedback Writing Exercise on Radial Artery Blood Flow and Neck Mobility

    PubMed Central

    Krullaards, Rob L.; Pel, Johan J. M.; Snijders, Chris J.; Kleinrensink, Gert-Jan

    2009-01-01

    Background: It has been suggested that sustained contraction of the deep neck muscles may reduce axial cervical range of motion (CROM) and radial artery blood flow velocity (vrad.art.mean). No studies have reported both phenomena in relation to acute hand, shoulder or neck trauma. Procedures: The CROM and vrad.art.mean were measured in 20 police officers prior to and immediately after a 2-hours drive on a motorcycle and immediately after a 1-minute writing exercise using biofeedback. The CROM was measured using separate inclinometers and the vrad.art.mean was measured in both arms just proximal to the wrist using echo-Doppler. Findings: During the study, one officer had a motorcycle accident resulting in acute symptoms of neck trauma. His vrad.art.mean was acutely reduced by 73% (right arm) and 45% (left arm). Writing with biofeedback increased his vrad.art.mean by 150% (right arm) and 80% (left arm). In the remaining 19 officers, the CROM to the right was significantly increased after the 2-hours driving task (p<0.05; paired subject t-test). Writing with biofeedback increased their CROM in both directions and vrad.art.mean in both arms (p<001). Conclusions: A 2-hours drive showed modest physical changes in the upper extremities. Biofeedback in writing tasks might relate to the influence of relaxation and diverting attention for neck mobility and arterial blood flow improvement. PMID:23675136

  2. Flow-Mediated Change in Viscoelastic Property of Radial Arterial Wall Measured by 22 MHz Ultrasound

    NASA Astrophysics Data System (ADS)

    Ikeshita, Kazuki; Hasegawa, Hideyuki; Kanai, Hiroshi

    2009-07-01

    The endothelial dysfunction is considered to be an initial step in atherosclerosis. Additionally, it was reported that the smooth muscle, which constructs the media of the artery, changes its characteristics owing to atherosclerosis. Therefore, it is essential to develop a method of assessing the regional endothelial function and mechanical properties of the arterial wall. To evaluate the endothelial function, a conventional technique of measuring the transient change in the diameter of the brachial artery caused by flow-mediated dilation (FMD) after the release of avascularization is used. However, this method can not evaluate the mechanical properties of the wall. We previously developed a method for the simultaneous measurements of waveforms of radial strain and blood pressure in the radial artery. In this study, the viscoelasticity of the arterial wall was estimated from the measured stress-strain relationship using the least-squares method and the transient changes in the mechanical properties of the arterial wall ware revealed. From in vivo experimental results, the stress-strain relationship showed a hysteresis loop and viscoelasticity was estimated by the proposed method. The slope of the loop decreased owing to FMD, which resulted in the decrease in estimated elastic modulus. The increase in the area of the loop occurred after recirculation, which corresponds to the increase in the ratio of the loss modulus (depends on viscosity) to the elastic modulus when the Voigt model is assumed. In this study, the variance in estimates was evaluated by in vivo measurement for 10 min. The temporal decrease in static elasticity after recirculation due to FMD was much larger than the evaluated variance. These results show a potential of the proposed method for the thorough analysis of the transient change in viscoelasticity due to FMD.

  3. Study of Radially Varying Magnetic Field on Blood Flow through Catheterized Tapered Elastic Artery with Overlapping Stenosis

    NASA Astrophysics Data System (ADS)

    Nadeem, S.; Ijaz, S.

    2015-11-01

    A precise model has been developed for studying the influence of metallic nanoparticles on blood flow through catheterized tapered elastic arteries with radially varying magnetic field. The model is solved under the mild stenosis approximation by considering blood as viscous fluid. The influence of different flow parameters associated with this problem such as Hartmann number, nanoparticle volume fraction, Grashof number and heat source or sink parameter is analyzed by plotting the graphs of the wall shear stress, resistance impedance to blood flow and stream lines. The influence of the radially varying magnetic field on resistance impedance to flow is analyzed and it is observed that the significantly strong magnetic force tends to increase in resistance.

  4. Evaluation of Radial Flow Fluidized Filter (R3F) Followed by Microfiltration and Ultrafiltration Systems in Calimesa, California

    EPA Science Inventory

    U.S. EPA coordinated a field study with South Mesa Water Utility to look for treatment alternatives for California State Project Water in the small community of Calimesa, California. EPA evaluated the performance of a system comprised of Radial Flow Fluidized Filtration (R3f) fo...

  5. 1r2dinv: A finite-difference model for inverse analysis of two dimensional linear or radial groundwater flow

    USGS Publications Warehouse

    Bohling, G.C.; Butler, J.J., Jr.

    2001-01-01

    We have developed a program for inverse analysis of two-dimensional linear or radial groundwater flow problems. The program, 1r2dinv, uses standard finite difference techniques to solve the groundwater flow equation for a horizontal or vertical plane with heterogeneous properties. In radial mode, the program simulates flow to a well in a vertical plane, transforming the radial flow equation into an equivalent problem in Cartesian coordinates. The physical parameters in the model are horizontal or x-direction hydraulic conductivity, anisotropy ratio (vertical to horizontal conductivity in a vertical model, y-direction to x-direction in a horizontal model), and specific storage. The program allows the user to specify arbitrary and independent zonations of these three parameters and also to specify which zonal parameter values are known and which are unknown. The Levenberg-Marquardt algorithm is used to estimate parameters from observed head values. Particularly powerful features of the program are the ability to perform simultaneous analysis of heads from different tests and the inclusion of the wellbore in the radial mode. These capabilities allow the program to be used for analysis of suites of well tests, such as multilevel slug tests or pumping tests in a tomographic format. The combination of information from tests stressing different vertical levels in an aquifer provides the means for accurately estimating vertical variations in conductivity, a factor profoundly influencing contaminant transport in the subsurface. ?? 2001 Elsevier Science Ltd. All rights reserved.

  6. Experimental evaluation of connectivity influence on dispersivity under confined and unconfined radial convergent flow conditions

    NASA Astrophysics Data System (ADS)

    Guzzi, Silvia; Molinari, Antonio; Fallico, Carmine; Pedretti, Daniele

    2014-05-01

    Heterogeneity and connectivity have a significant impact on the fate and transport of contaminants due to the occurrence of formations with largest permeability than the surrounding geological materials, which can originate preferential pathways in groundwater system. These issues are usually addressed by tracer tests and a radial convergent (RC) flow setting is typically selected for convenience but more complicated for model interpretation than uniform flow transport. An experimental investigation was performed using RC tracer tests in a 3D intermediate scale physical model to illustrate the role of connected features on the estimation of dispersivity using the classical Sauty solution and the method of moments, under confined and unconfined aquifer conditions. The physical model consists of 26 piezometers located at difference distances from a constant-discharge central pumping well. The box is filled with gravel channels embedded in a sandy matrix and organized in different layers. Materials have been well characterized before and after the test. For the confined configuration, a silt layer was placed above the previous layers. Tracer tests were performed using potassium iodide solutions with concentration of 3•10-3 M and under a constant pumping flow rate of 0.05 L/s. To mimic a pulse injection in each piezometer we used syringes and pipes, whereas a probe allowed continuous measuring of tracer concentration. Average velocity and longitudinal dispersion coefficient were defined from the first and second central moment of the observed breakthrough curves for each piezometer (integrated over the outflow boundary of the domain) and using the classical curve matching from the Sauty's solution at different Péclet numbers. Results reveal in some cases that estimates of hydrodynamic parameters from the Sauty solution and the method of moments seem to be different. This is related to the different basic assumptions of the two methods applied, and especially because

  7. Flow Characterization and Dynamic Analysis of a Radial Compressor with Passive Method of Surge Control

    NASA Astrophysics Data System (ADS)

    Guillou, Erwann

    Due to recent emission regulations, the use of turbochargers for force induction of internal combustion engines has increased. Actually, the trend in diesel engines is to downsize the engine by use of turbochargers that operate at higher pressure ratio. Unfortunately, increasing the rotational speed tends to reduce the turbocharger radial compressor range of operation which is limited at low mass flow rate by the occurrence of surge. In order to extent the operability of turbochargers, compressor housings can be equipped with a passive surge control device also known as ported shroud. This specific casing treatment has been demonstrated to enhance surge margin with minor negative impact on the compressor efficiency. However, the actual working mechanisms of the bypass system remain not well understood. In order to optimize the design of the ported shroud, it is then crucial to identify the dynamic flow changes induced by the implementation of the device to control instabilities. Experimental methods were used to assess the development of instabilities from stable, stall and eventually surge regimes of a ported shroud centrifugal compressor. Systematic comparison was conducted with the same compressor design without ported shroud. Hence, the full pressure dynamic survey of both compressors' performance characteristics converged toward two different and probably interrelated driving mechanisms to the development and/or propagation of unsteadiness within each compressor. One related the pressure disturbances at the compressor inlet, and notably the more apparent development of perturbations in the non-ported compressor impeller, whereas the other was attributed to the pressure distortions induced by the presence of the tongue in the asymmetric design of the compressor volute. Specific points of operation were selected to carry out planar flow measurements. At normal working, both standard and stereoscopic particle imaging velocimetry (PIV) measurements were performed

  8. Theoretical analysis of inertially irrotational and solenoidal flow in two-dimensional radial-flow pump and turbine impellers with equiangular blades

    NASA Astrophysics Data System (ADS)

    Visser, F. C.; Brouwers, J. J. H.; Badie, R.

    1994-06-01

    Using the theory of functions of a complex variable, in particular the method of conformal mapping, the irrotational and solenoidal flow in two-dimensional radial-flow pump and turbine impellers fitted with equiangular blades is analyzed. Exact solutions are given for the fluid velocity along straight radial pump and turbine impeller blades, while for logarithmic spiral pump impeller blades solutions are given which hold asymptotically as (r(sub 1)/r(sub 2))(exp n) approaches 0, in which r(sub 1) is impeller inner radius, r(sub 2) is impeller outer radius, and n is the number of blades. Both solutions are given in terms of a Fourier series, with the Fourier coefficients being given by the (Gauss) hypergeometric function and the beta function respectively. The solutions are used to derive analytical expressions for a number of parameters which are important for practical design of radial turbomachinery, and which reflect the two-dimensional nature of the flow field. Parameters include rotational slip of the flow leaving radial impellers, conditions to avoid reverse flow between impeller blades, and conditions for shockless flow at impeller entry, with the number of blades and blade curvature as variables. Furthermore, analytical extensions to classical one-dimensional Eulerian-based expressions for developed head of pumps and delivered work of turbines are given.

  9. A Miniature Radial-Flow Wind Turbine Using Piezoelectric Transducers and Magnetic Excitation

    NASA Astrophysics Data System (ADS)

    Fu, H.; Yeatman, E. M.

    2015-12-01

    This paper presents a miniature radial-flow piezoelectric wind turbine for harvesting airflow energy. The turbine's transduction is achieved by magnetic “plucking”of a piezoelectric beam by the passing rotor. The magnetic coupling is formed by two magnets on the beam's free end and on the rotor plate. Frequency up-conversion is realized by the magnetic excitation, allowing the rotor to rotate at any low frequency while the beam can vibrate at its resonant frequency after each plucking. The operating range of the device is, therefore, expanded by this mechanism. Two arrangements of magnetic orientation have been investigated, showing that the repulsive arrangement has higher output power. The influence of the vertical gap between magnets was also examined, providing guidance for the final design. A prototype was built and tested in a wind tunnel. A peak power output of 159 μW was obtained with a 270 kΩ load at 2.7 m/s airflow speed. The device started working at 3.5 m/s and kept operating when the airflow speed fell to 1.84 m/s.

  10. Linear stability of a circular Couette flow under a radial thermoelectric body force

    NASA Astrophysics Data System (ADS)

    Yoshikawa, H. N.; Meyer, A.; Crumeyrolle, O.; Mutabazi, I.

    2015-03-01

    The stability of the circular Couette flow of a dielectric fluid is analyzed by a linear perturbation theory. The fluid is confined between two concentric cylindrical electrodes of infinite length with only the inner one rotating. A temperature difference and an alternating electric tension are applied to the electrodes to produce a radial dielectrophoretic body force that can induce convection in the fluid. We examine the effects of superposition of this thermoelectric force with the centrifugal force including its thermal variation. The Earth's gravity is neglected to focus on the situations of a vanishing Grashof number such as microgravity conditions. Depending on the electric field strength and of the temperature difference, critical modes are either axisymmetric or nonaxisymmetric, occurring in either stationary or oscillatory states. An energetic analysis is performed to determine the dominant destabilizing mechanism. When the inner cylinder is hotter than the outer one, the circular Couette flow is destabilized by the centrifugal force for weak and moderate electric fields. The critical mode is steady axisymmetric, except for weak fields within a certain range of the Prandtl number and of the radius ratio of the cylinders, where the mode is oscillatory and axisymmetric. The frequency of this oscillatory mode is correlated with a Brunt-Väisälä frequency due to the stratification of both the density and the electric permittivity of the fluid. Under strong electric fields, the destabilization by the dielectrophoretic force is dominant, leading to oscillatory nonaxisymmetric critical modes with a frequency scaled by the frequency of the inner-cylinder rotation. When the outer cylinder is hotter than the inner one, the instability is again driven by the centrifugal force. The critical mode is axisymmetric and either steady under weak electric fields or oscillatory under strong electric fields. The frequency of the oscillatory mode is also correlated with the

  11. The origins of radial fracture systems and associated large lava flows on Venus

    NASA Technical Reports Server (NTRS)

    Parfitt, Elisabeth A.; Wilson, Lionel; Head, James W., III

    1992-01-01

    Magellan images have revealed the existence of systems of radial fractures on venus that are very similar in form to terrestrial dike swarms such as the Mackenzie swarm in Northern Canada. The association of many of the fracture systems with lava flows, calderas, and volcanic edifices further support the idea of a dike emplacement origin. A global survey of the Magellan images has allowed the location of 300 such fracture systems. Two types of fracture systems are defined. A series of models were developed to simulate the emplacement of dikes on Venus. Observations of fracture lengths and widths were then used to constrain the emplacement conditions. The model results show that the great length and relatively large width of the fractures can only be explained if the dikes that produce them were emplaced in high driving pressure (pressure buffered) conditions. Such conditions imply high rates of melt production, which is consistent with the melt being derived directly from a plume head. We have recently modeled the vertical emplacement of a dike from the top of a mantle plume and calculated the eruption rates such a dike would produce on reaching the surface. This modeling shows that eruption rates of approximately 0.1 cu km/hr can readily be generated by such a dike, consistent with the above results. However, the sensitivity of the model to dike width and therefore driving pressure means that eruption rates from dikes emplaced from the base of the crust or the head of a mantle plume could be orders of magnitude higher than this. Clearly, therefore, the model needs to be refined in order to better constrain eruption conditions. However, it is worth noting here that the initial results do show that even for moderate dike widths, eruption rates could be at least on the order of those estimated for terrestrial flood basalts.

  12. Aerothermal investigations of mixing flow phenomena in case of radially inclined ejection holes at the leading edge

    SciTech Connect

    Bohn, D.E.; Kusterer, K.A.

    2000-04-01

    A leading edge cooling configuration is investigated numerically by application of a three-dimensional conjugate fluid flow and heat transfer solver, CHT-flow. The code has been developed at the Institute of Steam and Gas Turbines, Aachen University of Technology. It works on the basis of an implicit finite volume method combined with a multi-block technique. The cooling configuration is an axial turbine blade cascade with leading edge ejection through two rows of cooling holes. The rows are located in the vicinity of the stagnation line, one row on the suction side, the other row is on the pressure side. the cooling holes have a radial ejection angle of 45 degrees. This configuration has been investigated experimentally by other authors and the results have been documented as a test case for numerical calculations of ejection flow phenomena. The numerical investigations focus on the aerothermal mixing process in the cooling jets and the impact on the temperature distribution on the blade surface. The radial ejection angles lead to a fully three-dimensional and asymmetric jet flow field. Within a secondary flow analysis, the cooling fluid jets are investigated in detail. The secondary flow fields include asymmetric kidney vortex systems with one dominating vortex on the back side of the jets. The numerical and experimental data show a respectable agreement concerning the vortex development.

  13. Characterization of azimuthal and radial velocity fields induced by rotors in flows with a low Reynolds number

    NASA Astrophysics Data System (ADS)

    Köhler, J.; Friedrich, J.; Ostendorf, A.; Gurevich, E. L.

    2016-02-01

    We theoretically and experimentally investigate the flow field that emerges from a rodlike microrotor rotating about its center in a nonaxisymmetric manner. A simple theoretical model is proposed that uses a superposition of two rotlets as a fundamental solution to the Stokes equation. The predictions of this model are compared to measurements of the azimuthal and radial microfluidic velocity field components that are induced by a rotor composed of fused microscopic spheres. The rotor is driven magnetically and the fluid flow is measured with the help of a probe particle fixed by an optical tweezer. We find considerable deviations of the mere azimuthal flow pattern induced by a single rotating sphere as it has been reported by Di Leonardo et al. [Phys. Rev. Lett. 96, 134502 (2006), 10.1103/PhysRevLett.96.134502]. Notably, the presence of a radial velocity component that manifests itself by an oscillation of the probe particle with twice the rotor frequency is observed. These findings open up a way to discuss possible radial transport in microfluidic devices.

  14. Characterization of azimuthal and radial velocity fields induced by rotors in flows with a low Reynolds number.

    PubMed

    Köhler, J; Friedrich, J; Ostendorf, A; Gurevich, E L

    2016-02-01

    We theoretically and experimentally investigate the flow field that emerges from a rodlike microrotor rotating about its center in a nonaxisymmetric manner. A simple theoretical model is proposed that uses a superposition of two rotlets as a fundamental solution to the Stokes equation. The predictions of this model are compared to measurements of the azimuthal and radial microfluidic velocity field components that are induced by a rotor composed of fused microscopic spheres. The rotor is driven magnetically and the fluid flow is measured with the help of a probe particle fixed by an optical tweezer. We find considerable deviations of the mere azimuthal flow pattern induced by a single rotating sphere as it has been reported by Di Leonardo et al. [Phys. Rev. Lett. 96, 134502 (2006)]. Notably, the presence of a radial velocity component that manifests itself by an oscillation of the probe particle with twice the rotor frequency is observed. These findings open up a way to discuss possible radial transport in microfluidic devices. PMID:26986414

  15. Results from Evaluation of Representative ASME AG-1 Section FK Radial Flow Dimple Pleated HEPA Filters Under Elevated Conditions - 12002

    SciTech Connect

    Giffin, Paxton K.; Parsons, Michael S.; Rickert, Jaime G.; Waggoner, Charles A.

    2012-07-01

    The American Society of Mechanical Engineers (ASME) has recently added Section FK establishing requirements for radial flow HEPA filters to the Code on Nuclear Air and Gas Treatment (AG-1). Section FK filters are expected to be a major element in the HEPA filtration systems across the US Department of Energy (DOE) complex. Radial flow filters have been used in Europe for some time, however a limited amount of performance evaluation data exists with respect to these new AG-1 Section FK units. In consultation with a technical working group, the Institute for Clean Energy Technology (ICET) at Mississippi State University (MSU)has evaluated a series of representative AG-1 Section FK dimple pleated radial flow HEPA filters. The effects of elevated relative humidity and temperature conditions on these filters are particularly concerning. Results from the evaluation of Section FK filters under ambient conditions have been presented at the 2011 waste management conference. Additions to the previous test stand to enable high temperature and high humidity testing, a review of the equipment used, the steps taken to characterize the new additions, and the filter test results are presented in this study. Test filters were evaluated at a volumetric flow rate of 56.6 m{sup 3}/min (2000 cfm) and were challenged under ambient conditions with Alumina, Al(OH){sub 3}, until reaching a differential pressure of 1 kPa (4 in. w.c.), at which time the filters were tested, unchallenged with aerosol, at 54 deg. C (130 deg. F) for approximately 1 hour. At the end of that hour water was sprayed near the heat source to maximize vaporization exposing the filter to an elevated relative humidity up to 95%. Collected data include differential pressure, temperature, relative humidity, and volumetric flow rate versus time. (authors)

  16. A comparison of the calculated and experimental off-design performance of a radial flow turbine

    NASA Technical Reports Server (NTRS)

    Tirres, Lizet

    1992-01-01

    Off design aerodynamic performance of the solid version of a cooled radial inflow turbine is analyzed. Rotor surface static pressure data and other performance parameters were obtained experimentally. Overall stage performance and turbine blade surface static to inlet total pressure ratios were calculated by using a quasi-three dimensional inviscid code. The off design prediction capability of this code for radial inflow turbines shows accurate static pressure prediction. Solutions show a difference of 3 to 5 points between the experimentally obtained efficiencies and the calculated values.

  17. A comparison of the calculated and experimental off-design performance of a radial flow turbine

    NASA Technical Reports Server (NTRS)

    Tirres, Lizet

    1991-01-01

    Off design aerodynamic performance of the solid version of a cooled radial inflow turbine is analyzed. Rotor surface static pressure data and other performance parameters were obtained experimentally. Overall stage performance and turbine blade surface static to inlet total pressure ratios were calculated by using a quasi-three dimensional inviscid code. The off design prediction capability of this code for radial inflow turbines shows accurate static pressure prediction. Solutions show a difference of 3 to 5 points between the experimentally obtained efficiencies and the calculated values.

  18. Viscous Fingering Induced Flow Instability in Multidimensional Liquid Chromatography

    SciTech Connect

    Mayfield, Kirsty; Shalliker, R. Andrew; Catchpoole, Heather J.; Sweeney, Alan P.; Wong, Victor; Guiochon, Georges A

    2005-07-01

    Viscous fingering is a flow instability phenomenon that results in the destabilisation of the interface between two fluids of differing viscosities. The destabilised interface results in a complex mixing of the two fluids in a pattern that resembles fingers. The conditions that enhance this type of flow instability can be found in coupled chromatographic separation systems, even when the solvents used in each of the separation stages have seemingly similar chemical and physical properties (other than viscosity). For example, the viscosities of acetonitrile and methanol are sufficiently different that instability at the interface between these two solvents can be established and viscous fingering results. In coupled chromatographic systems, the volume of solvent transported from one separation dimension to the second often exceeds the injection volume by two or more orders of magnitude. As a consequence, viscous fingering may occur, when otherwise following the injection of normal analytical size injection plugs viscous fingering would not occur. The findings in this study illustrate the onset of viscous fingering in emulated coupled chromatographic systems and show the importance of correct solvent selection for optimum separation performance.

  19. Accurate on-line mass flow measurements in supercritical fluid chromatography.

    PubMed

    Tarafder, Abhijit; Vajda, Péter; Guiochon, Georges

    2013-12-13

    This work demonstrates the possible advantages and the challenges of accurate on-line measurements of the CO2 mass flow rate during supercritical fluid chromatography (SFC) operations. Only the mass flow rate is constant along the column in SFC. The volume flow rate is not. The critical importance of accurate measurements of mass flow rates for the achievement of reproducible data and the serious difficulties encountered in supercritical fluid chromatography for its assessment were discussed earlier based on the physical properties of carbon dioxide. In this report, we experimentally demonstrate the problems encountered when performing mass flow rate measurements and the gain that can possibly be achieved by acquiring reproducible data using a Coriolis flow meter. The results obtained show how the use of a highly accurate mass flow meter permits, besides the determination of accurate values of the mass flow rate, a systematic, constant diagnosis of the correct operation of the instrument and the monitoring of the condition of the carbon dioxide pump. PMID:24210558

  20. A Galerkin finite-element flow model to predict the transient response of a radially symmetric aquifer

    USGS Publications Warehouse

    Reilly, Thomas E.

    1984-01-01

    A computer program developed to evaluate radial flow of ground water, such as at a pumping well, recharge basin, or injection well, is capable of simulating anisotropic, inhomogenous, confined, or pseudo-unconfined (constant saturated thickness) conditions. Results compare well with those calculated from published analytical and model solutions. The program is based on the Galerkin finite-element technique. A sample model run is presented to illustrate the use of the program; supplementary material provides the program listing as well as a sample problem data set and output. From the text and other material presented, one can use the program to predict drawdowns from pumping and ground-water buildups from recharge in a radially symmetric ground-water system.

  1. A design methodology for a magnetorheological fluid damper based on a multi-stage radial flow mode

    NASA Astrophysics Data System (ADS)

    Liao, C. R.; Zhao, D. X.; Xie, L.; Liu, Q.

    2012-08-01

    In this paper, a magnetorheological (MR) fluid damper based on a multi-stage radial flow mode is put forward, compared with traditional ones with annular damping channel which are of low magnetic field utilization and high energy consumption. The equivalent magnetic circuit model is derived, along with the relation between the magnetic induction at the working gap and the exciting current in the field coils. The finite-element software ANYSY is used to analyze the distribution of the magnetic field in the MR valve. The flow differential equation for a MR fluid in radial flow is theoretically set up, and the numerical solution is validated by means of the Herschel-Bulkley constitutive model. A MR damper was designed and fabricated in Chongqing University in accordance with the technical requirements of a railway vehicle anti-yaw damper, and the force-displacement characteristic of the damper was tested with J95-I type shock absorber test-bed. The results show that the experimental damping forces are in good agreement with the analytical ones, and the methodology is believed to help predict the damping force of a MR damper.

  2. Onset of radial flow in p+p collisions

    SciTech Connect

    Jiang, Kun; Zhu, Yinying; Liu, Weitao; Chen, Hongfang; Li, Cheng; Ruan, Lijuan; Tang, Zebo; Xu, Zhangbu

    2015-02-23

    It has been debated for decades whether hadrons emerging from p+p collisions exhibit collective expansion. The signal of the collective motion in p+p collisions is not as clear as in heavy-ion collisions because of the low multiplicity and large fluctuation in p+p collisions. Tsallis Blast-Wave (TBW) model is a thermodynamic approach, introduced to handle the overwhelming correlation and fluctuation in the hadronic processes. We have systematically studied the identified particle spectra in p+p collisions from RHIC to LHC using TBW and found no appreciable radial flow in p+p collisions below √s = 900 GeV. At LHC higher energy of 7 TeV in p+p collisions, the radial flow velocity achieves an average of (β) = 0.320 ± 0.005. This flow velocity is comparable to that in peripheral (40-60%) Au+Au collisions at RHIC. In addition, breaking of the identified particle spectra mT scaling was also observed at LHC from a model independent test.

  3. Thermal stresses due to a uniform heat flow past a circular hole with a radial edge crack

    SciTech Connect

    Edmonds, G.F.

    1987-01-01

    The problem solved here is that of finding the stresses in an isotropic, linear, thermoelastic solid when a uniform heat flow is disturbed by the presence of an insulated circular hole with a radial edge crack. By superimposing a Mellin-transform solution of the equations of thermoelasticity on a Michell series solution the author reduces the problem to a pair of singular integral equations which are then solved numerically. The stress-intensity factors and crack-formation energies, quantities of interest to workers in fracture mechanics, are then calculated.

  4. Direct, simultaneous measurement of chloramphenicol and its monosuccinate ester in micro-samples of plasma by radial-compression liquid chromatography.

    PubMed

    el-Yazigi, A; Yusuf, A; Al-Humaidan, A

    1987-10-01

    A simple method of simultaneous analysis for chloramphenicol and chloramphenicol succinate in 10-microL samples of plasma is described. We injected the plasma samples directly into a radial-compression liquid chromatograph equipped with a precolumn module and a C18 insert. A mixture of acetic acid solution (pH 3)/acetonitrile (75/25, by vol) was used as mobile phase, at a flow rate of 4 mL/min. We separated the compounds in a 10-micron (particle size) C18 cartridge with a radial compression separation system and detected them in the effluent at 280 nm. The peak height for both compounds was linearly (r greater than 0.9993) related to concentration over the range investigated, 1-50 mg/L. We also performed the analysis with use of an internal standard (methylprednisolone) and obtained equally good results (r greater than 0.9995). We observed no interference from other antibiotics or drugs in the assay, and the inter- and intra-run precision at different concentrations was good (CV, 0 to 5.6%). We analyzed microsamples of plasma from an infant treated for meningitis with chloramphenicol sodium succinate intravenously. Total analysis time for each sample was less than 8 min. PMID:3665035

  5. A systematic analysis of a flow-switching modulator for comprehensive two-dimensional gas chromatography.

    PubMed

    Laclair, Russell W; Bueno, Pedro A; Seeley, John V

    2004-04-01

    A simple flow-switching device has been designed for use as a comprehensive two-dimensional gas chromatography modulator. The device is constructed from fused silica tubing, t-unions, and a solenoid valve. A series of experiments were conducted to determine the influence of primary flow, secondary flow, modulation time, and device dimensions on the performance of the modulator. The flow-switching device was found to produce pulses with widths near the theoretical minimum. High-performance was maintained over a wide range of modulation times. The flow-switching device did not introduce extra broadening along the primary retention axis. However, the modulator performance was optimal only over a narrow range of primary to secondary flow ratios. The ideal flow ratio is determined by the dimensions of the tubes that connect the t-unions. A simple flow resistance model has been developed that can predict the dimensions that will produce optimal results for a specified primary to secondary flow ratio. Thus, it is possible to construct a device that operates near the theoretical limit without numerous alterations. Under optimal conditions, the flow switching modulator generates peaks that are narrower than those produced by a diaphragm valve. PMID:15335074

  6. Final Technical Report: Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    SciTech Connect

    Schuster, Eugenio

    2014-05-02

    The strong coupling between the different physical variables involved in the plasma transport phenomenon and the high complexity of its dynamics call for a model-based, multivariable approach to profile control where those predictive models could be exploited. The overall objective of this project has been to extend the existing body of work by investigating numerically and experimentally active control of unstable fluctuations, including fully developed turbulence and the associated cross-field particle transport, via manipulation of flow profiles in a magnetized laboratory plasma device. Fluctuations and particle transport can be monitored by an array of electrostatic probes, and Ex B flow profiles can be controlled via a set of biased concentric ring electrodes that terminate the plasma column. The goals of the proposed research have been threefold: i- to develop a predictive code to simulate plasma transport in the linear HELCAT (HELicon-CAThode) plasma device at the University of New Mexico (UNM), where the experimental component of the proposed research has been carried out; ii- to establish the feasibility of using advanced model-based control algorithms to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles, iii- to investigate the fundamental nonlinear dynamics of turbulence and transport physics. Lehigh University (LU), including Prof. Eugenio Schuster and one full-time graduate student, has been primarily responsible for control-oriented modeling and model-based control design. Undergraduate students have also participated in this project through the National Science Foundation Research Experience for Undergraduate (REU) program. The main goal of the LU Plasma Control Group has been to study the feasibility of controlling turbulence-driven transport by shaping the radial poloidal flow profile (i.e., by controlling flow shear) via biased concentric ring electrodes.

  7. Hydrodynamic chromatography using flow of a highly concentrated dextran solution through a coiled tube.

    PubMed

    Miyagawa, Yoichi; Morisada, Shintaro; Ohto, Keisuke; Hidetaka, Kawakita

    2016-08-01

    Separation of colloidal particles in non-Newtonian fluid is important in food engineering. Using hydrodynamic chromatography, colloidal particles and starch granules originating from corn were individually injected into dextran solutions (Mw 2,000,000g/mol) flowing through a coiled tube for efficient size separation. Rheological properties of dextran solutions ranging from 50 to 250g/L were determined, revealing pseudoplastic fluid behavior. Velocity profiles for dextran solution flow in coiled tubes were obtained from rheological power law parameters. Suspensions of colloidal particles of diameters 1.0 and 20μm were individually injected into the dextran flows, demonstrating that dextran solutions at high concentration separated colloidal particles. Starch granules were separated by size using a dextran solution flow (250g/L). Thus, we expect to obtain efficient separation of colloidal particles in foods using highly concentrated dextran solutions. PMID:27112856

  8. A radial flow microfluidic device for ultra-high-throughput affinity-based isolation of circulating tumor cells.

    PubMed

    Murlidhar, Vasudha; Zeinali, Mina; Grabauskiene, Svetlana; Ghannad-Rezaie, Mostafa; Wicha, Max S; Simeone, Diane M; Ramnath, Nithya; Reddy, Rishindra M; Nagrath, Sunitha

    2014-12-10

    Circulating tumor cells (CTCs) are believed to play an important role in metastasis, a process responsible for the majority of cancer-related deaths. But their rarity in the bloodstream makes microfluidic isolation complex and time-consuming. Additionally the low processing speeds can be a hindrance to obtaining higher yields of CTCs, limiting their potential use as biomarkers for early diagnosis. Here, a high throughput microfluidic technology, the OncoBean Chip, is reported. It employs radial flow that introduces a varying shear profile across the device, enabling efficient cell capture by affinity at high flow rates. The recovery from whole blood is validated with cancer cell lines H1650 and MCF7, achieving a mean efficiency >80% at a throughput of 10 mL h(-1) in contrast to a flow rate of 1 mL h(-1) standardly reported with other microfluidic devices. Cells are recovered with a viability rate of 93% at these high speeds, increasing the ability to use captured CTCs for downstream analysis. Broad clinical application is demonstrated using comparable flow rates from blood specimens obtained from breast, pancreatic, and lung cancer patients. Comparable CTC numbers are recovered in all the samples at the two flow rates, demonstrating the ability of the technology to perform at high throughputs. PMID:25074448

  9. Viscoelastic flow-focusing in microchannels: scaling properties of the particle radial distributions.

    PubMed

    Romeo, Giovanni; D'Avino, Gaetano; Greco, Francesco; Netti, Paolo A; Maffettone, Pier Luca

    2013-07-21

    Particles suspended in non-Newtonian liquids flowing in channels may migrate transversally to the main flow direction as a result of normal stress gradients. Viscoelasticity-induced migration has proven to be an efficient mechanism to promote 3D flow-focusing in cylindrical microchannels, avoiding the need for complex and expensive apparati. In this work, we demonstrate the existence of a single dimensionless number (Θ) that governs the migration dynamics of particles in viscoelastic liquids flowing in micropipes at low Deborah numbers (Deborah number is the ratio of fluid and flow characteristic times). The definition of Θ in terms of the relevant fluid, flow and geometrical quantities is obtained by generalizing the particle migration velocity expression given in previous asymptotic analytical theories through numerical simulations. An extensive experimental investigation quantitatively confirms the novel predictions: the experimental particle distributions along the channel axial direction collapse on a single curve when rescaled in terms of the proposed dimensionless number. The results reported in this work give a simple and general way to define the flow-focusing conditions promoted by viscoelastic effects. PMID:23670133

  10. Universality Results for Multi-layer Radial Hele-Shaw Flows

    NASA Astrophysics Data System (ADS)

    Daripa, Prabir; Gin, Craig; Daripa Research Team

    2014-03-01

    Saffman-Taylor instability is a well known viscosity driven instability of an interface separating two immiscible fluids. We study linear stability of this displacement process in multi-layer radial Hele-Shaw geometry involving an arbitrary number of immiscible fluid phases. Universal stability results have been obtained and applied to design displacement processes that are considerably less unstable than the pure Saffman-Taylor case. In particular, we derive universal formula which gives specific values of the viscosities of the fluid layers corresponding to smallest unstable band. Other similar universal results will also be presented. The talk is based on ongoing work. Supported by an NPRP Grant # 08-777-1-141 from the Qatar National Research Fund (a member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors.

  11. Radial Hele-Shaw flow with suction: Fully nonlinear pattern formation

    NASA Astrophysics Data System (ADS)

    Chen, Ching-Yao; Huang, Yu-Sheng; Miranda, José A.

    2014-05-01

    We study the development of intricate, fully nonlinear immiscible interfacial patterns in the suction-driven radial Hele-Shaw problem. The complex-shaped, contracting fluid-fluid interface arises when an initially circular blob of more viscous fluid, surrounded by less viscous one, is drawn into an eccentric point sink. We present sophisticated numerical simulations, based on a diffuse interface model, that capture the most prominent interfacial features revealed by existing experimental studies of the problem. The response of the system to changes in the capillary number is investigated, accurately revealing the occurrence of finger competition phenomena, and correctly describing the velocity behavior of both inward- and outward-pointing fingers. For the large-capillary-number regime, a set of complex interfacial features (finger merging, shielding, and pinch-off) whose experimental realization is still not available, are predicted.

  12. Measurement of radionuclides using ion chromatography and flow-cell scintillation counting with pulse shape discrimination

    SciTech Connect

    DeVol, T.A.; Fjeld, R.A.

    1995-10-01

    The use of ion chromatography (IC) for radiochemical separations is a well established technique. IC is commonly used in routine environmental monitoring applications as well as in specialized research applications. Typical usage involves the separation of a single radionuclide from the non-radioactive constituents. During the past decade, a limited amount of research has been conducted using automated IC systems in actinide separation applications (e.g.). More recently, separation procedures for common non-gamma emitting activation and fission products were developed utilizing a high performance liquid chromatography (HPLC) system. In addition, a separation procedure for six common actinides has been developed using a HPLC system. These latter systems used on-line flow-cell detectors for quantification of the radioactive constituents of the effluent stream.

  13. The investigation of flow instabilities on a rotating disk with curvature in the radial direction

    NASA Technical Reports Server (NTRS)

    Intemann, P. A.; Clarkson, M. H.

    1982-01-01

    The major objective is to explore any visible differences of the flow field with wall curvature of the test body, including possible interaction between Taylor-Gortler instabilities present along concave walls and the inflexional instabilities investigated here. An experimental study was conducted with emphasis placed on making visual observations and recording photographically the flow instabilities present under three different rotating bodies: a flat disk, a concave paraboloid, and a convex paraboloid. The data collected for the three test bodies lead to the conclusion that the wall curvature of the concave and convex paraboloids did not alter the observed flow field significantly from that observed on the flat disk.

  14. Simultaneous effects of radial magnetic field and wall properties on peristaltic flow of Carreau-Yasuda fluid in curved flow configuration

    NASA Astrophysics Data System (ADS)

    Hayat, T.; Tanveer, A.; Alsaadi, F.

    2015-12-01

    The objective of present article is to address the magnetohydrodynamic (MHD) peristaltic flow of Carreau-Yasuda fluid in a curved geometry. The channel boundaries satisfy wall slip and compliant properties. The fluid is electrically conducting through an applied magnetic field in the radial direction. Heat transfer is also studied. Governing equation comprised the viscous dissipation effects. The non-linear expressions are first obtained and then approximated using long wavelength and low Reynolds number considerations. The resulting systems are solved for the series solutions. The expressions of velocity, temperature, heat transfer coefficient and stream function are obtained and analyzed via graphical illustrations.

  15. Influence of long-scale length radial electric field components on zonal flow-like structures in the TJ-II stellarator

    NASA Astrophysics Data System (ADS)

    Losada, U.; Alonso, A.; van Milligen, B. Ph; Hidalgo, C.; Liu, B.; Pedrosa, M. A.; Silva, C.; the TJ-II team

    2016-08-01

    The influence of long-scale length radial electric fields on zonal flows-like structures has been studied in the TJ-II stellarator. This relation has been investigated in the edge plasma using two electrical rake probes. The results presented here show an empirical correlation between the properties of long-range correlations (LRCs) with zonal flow-like structures and the magnitude of radial (neoclassical, NC) electric fields in TJ-II neutral beam heated plasmas. These experimental findings show that the enhancement of the NC radial electric field \\boldsymbol{E}{\\mathbf{r}} increases the magnitude of LRCs, considered as a proxy of zonal flows, while the radial correlation length of the plasma potential fluctuations was found to decrease by about 40%. A strong relation between the magnitude of electric field structures with long and short radial scales was found. The calculated \\boldsymbol{E}{\\mathbf{r}}× \\boldsymbol{B} shearing rate corresponding to the short scale length structures of the radial electric field may be sufficient to regulate turbulence.

  16. An experimental and computational investigation of flow in a radial inlet of an industrial pipeline centrifugal compressor

    SciTech Connect

    Flathers, M.B.; Bache, G.E.; Rainsberger, R.

    1996-04-01

    The flow field of a complex three-dimensional radial inlet for an industrial pipeline centrifugal compressor has been experimentally determined on a half-scale model. Based on the experimental results, inlet guide vanes have been designed to correct pressure and swirl angle distribution deficiencies. The unvaned and vaned inlets are analyzed with a commercially available fully three-dimensional viscous Navier-Stokes code. Since experimental results were available prior to the numerical study, the unvaned analysis is considered a postdiction while the vaned analysis is considered a prediction. The computational results of the unvaned inlet have been compared to the previously obtained experimental results. The experimental method utilized for the unvaned inlet is repeated for the vaned inlet and the data have been used to verify the computational results. The paper will discuss experimental, design, and computational procedures, grid generation, boundary conditions, and experimental versus computational methods. Agreement between experimental and computational results is very good, both in prediction and postdiction modes. The results of this investigation indicate that CFD offers a measurable advantage in design, schedule, and cost and can be applied to complex, three-dimensional radial inlets.

  17. Electron source of triode type with radial converging electron flow for irradiation of cylindrical targets

    SciTech Connect

    Engelko, V. I.; Kuznetsov, V. S.; Mueller, Georg

    2009-01-15

    Design of an electron source of triode type is described, which produces a radial converging electron beam employed for modification of the outer surface of fuel element claddings. Experimental investigations of the source showed that beam current magnitude, efficiency of beam focusing to the target, stability of source operation, and beam pulse duration become worse when the target diameter drops below certain values. A method for the calculation of the source operation was developed. Calculations showed that the reason of worse source operation is the initial angular spread of electrons when the target diameter is small. Because of the angular spread a part of electrons passes by the target and oscillates between the target and cathode. The space charge of the oscillating electrons lowers the emission current magnitude and leads to the formation of a virtual cathode in the grid-target gap despite the fact that the emission beam current is less than the limiting one. Formation of a virtual cathode is a reason for the unstable source operation and restriction of the beam pulse duration. Recommendations for the improvement of the source design are suggested.

  18. Distributed control of reactive power flow in a radial distribution circuit with high photovoltaic penetration

    SciTech Connect

    Chertkov, Michael; Turitsyn, Konstantin; Backhaus, Scott; Sule, Petr

    2009-01-01

    We show how distributed control of reactive power can serve to regulate voltage and minimize resistive losses in a distribution circuit that includes a significant level of photovoltaic (PV) generation. To demonstrate the technique, we consider a radial distribution circuit with a single branch consisting of sequentially-arranged residential-scale loads that consume both real and reactive power. In parallel, some loads also have PV generation capability. We postulate that the inverters associated with each PV system are also capable of limited reactive power generation or consumption, and we seek to find the optimal dispatch of each inverter's reactive power to both maintain the voltage within an acceptable range and minimize the resistive losses over the entire circuit. We assume the complex impedance of the distribution circuit links and the instantaneous load and PV generation at each load are known. We compare the results of the optimal dispatch with a suboptimal local scheme that does not require any communication. On our model distribution circuit, we illustrate the feasibility of high levels of PV penetration and a significant (20% or higher) reduction in losses.

  19. [Radial variation and time lag of sap flow of Populus gansuensis in Minqin Oasis, Northwest].

    PubMed

    Dang, Hong-Zhong; Yang, Wen-Bin; Li, Wei; Zhang, You-Yan; Li, Chang-Long

    2014-09-01

    Sap flow of tree trunk is very important to reflect the dynamics of physiological activities, as well as to estimate the water consumption of individual plant. In the present study, we used the thermal dissipation technique to monitor the sap flow velocity (J) at four depth loci (i. e. 2 cm, 3 cm, 5 cm, 8 cm) of three Populus gansuensis trees (30 year-old) in Minqin Oasis for two consecutive growing seasons. The results showed that there were significant differences among J values at four depth loci under tree trunk cambium. J value at the 3 cm depth locus (J3) of the tree trunk was the highest, and then in sequences, were 2 cm, 5 cm and 8 cm depth loci (J2, J5 and J8). J value (J3) on typical sunny days in June with the highest atmospheric potential evapotranspiration (ET0) was up to 28.53 g · cm(-2) · h(-1), which was 1.42, 2.74 and 4.4 times of J2, J5 and J8, respectively. In the process of diurnal variation of sap flow velocity, the peak value time of J at the four depth loci of the tree trunk was different, but the differences among them were within 20 min. Furthermore, the peak value time of sap flow velocity was very different to that of solar radiation (Rs) and air vapour pressure deficit (VPD). The time lag between J and Rs was from 55 to 88 min on typical sunny days during the main growing seasons (from June to August), and, positively related to the depth of the locus under tree trunk cambium, while the time lag between J and VPD reached 60-96 min, and was negatively related to the depth of the locus. The seasonal variation patterns of J were consistent with ET0. With the increase of tree physiological activities, there was a trend that the major water transportation layer extended to the interior sapwood. The most important meteorological factor was the solar radiation, which primarily drove sap flow at different depths of tree trunk. However, the secondary factor changed along with the depth, and VPD became increasingly important with increasing the

  20. Flow modulation comprehensive two-dimensional gas chromatography-mass spectrometry using ≈4mLmin(-1) gas flows.

    PubMed

    Franchina, Flavio A; Maimone, Mariarosa; Tranchida, Peter Q; Mondello, Luigi

    2016-04-01

    The main objective of the herein described research was focused on performing satisfactory flow modulation (FM), in comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS), using an MS-compatible second-dimension gas flow of approx. 4mLmin(-1). The FM model used was based on that initially proposed by Seeley et al. [3]. The use of limited gas flows was enabled through fine tuning of the FM parameters, in particular the duration of the re-injection (or flushing) process. Specifically, the application of a long re-injection period (i.e., 700ms) enabled efficient accumulation-loop flushing with gas flows of about 4mLmin(-1). It was possible to apply such extended re-injection periods by using different restrictor lengths in the connections linking the modulator to the auxiliary pressure source. FM GC×GC-MS applications were performed on a mixture containing C9-10 alkanes, and on a sample of essential oil. GC×GC-MS sensitivity was compared with that attained by using conventional GC-MS analysis, in essential oil applications. It was observed that signal intensities were, in general, considerably higher in the FM GC×GC-MS experiments. PMID:26968229

  1. Reaction flow chromatography for rapid post column derivatisations: the analysis of antioxidants in natural products.

    PubMed

    Camenzuli, M; Ritchie, H J; Dennis, G R; Shalliker, R A

    2013-08-16

    The analysis of antioxidants from complex samples is conveniently achieved using liquid chromatography, which provides sample fraction, coupled with an on-line antioxidant assay, which provides detection. One particularly useful on-line antioxidant assay that has routinely been coupled with HPLC involves the diphenylpicrylhydrazyl radical (DPPH), which provides a positive test for phenolic antioxidants through a decolorisation of the DPPH reagent. A limitation of this assay, however, is the need to employ a reaction coil, which is often large with respect to the peak volume, consequently adding substantial band broadening to the separation. In this study we introduce a new concept that can be employed for systems requiring post column derivatisations, such as the DPPH assay. We have termed this 'reaction flow' chromatography, whereby, the derivatisation reagent can be added directly into one of the outlet ports of a parallel segmented flow column. Subsequently, the mixing between the derivatising reagent and the solute is very efficient removing the need to employ reaction coils. The concept is tested here using the DPPH assay for the analysis of antioxidants in samples derived from natural origin. PMID:23849586

  2. Rotor cavity flow and heat transfer with inlet swirl and radial outflow of cooling air

    NASA Astrophysics Data System (ADS)

    Staub, F. W.

    1992-06-01

    To enhance the reliability of turbine disk life prediction, experimental verification is necessary for analytical tools which calculate the heat transfer and flow field coefficients in turbine-stator cavities. A full-scale model of the forward cavity of a typical aircraft gas turbine is utilized employing a high-molecular-weight gas (Refrigerant-12) at ambient temperature and pressure conditions to match the dimensionless parameters at engine conditions. A first-order comparison is given of the velocity distribution and disk heat transfer coefficients calculated by the measured values and a CFD code.

  3. Approximate analysis of three-dimensional groundwater flow toward a radial collector well in a finite-extent unconfined aquifer

    NASA Astrophysics Data System (ADS)

    Huang, C.-S.; Chen, J.-J.; Yeh, H.-D.

    2016-01-01

    This study develops a three-dimensional (3-D) mathematical model for describing transient hydraulic head distributions due to pumping at a radial collector well (RCW) in a rectangular confined or unconfined aquifer bounded by two parallel streams and no-flow boundaries. The streams with low-permeability streambeds fully penetrate the aquifer. The governing equation with a point-sink term is employed. A first-order free surface equation delineating the water table decline induced by the well is considered. Robin boundary conditions are adopted to describe fluxes across the streambeds. The head solution for the point sink is derived by applying the methods of finite integral transform and Laplace transform. The head solution for a RCW is obtained by integrating the point-sink solution along the laterals of the RCW and then dividing the integration result by the sum of lateral lengths. On the basis of Darcy's law and head distributions along the streams, the solution for the stream depletion rate (SDR) can also be developed. With the aid of the head and SDR solutions, the sensitivity analysis can then be performed to explore the response of the hydraulic head to the change in a specific parameter such as the horizontal and vertical hydraulic conductivities, streambed permeability, specific storage, specific yield, lateral length, and well depth. Spatial head distributions subject to the anisotropy of aquifer hydraulic conductivities are analyzed. A quantitative criterion is provided to identify whether groundwater flow at a specific region is 3-D or 2-D without the vertical component. In addition, another criterion is also given to allow for the neglect of vertical flow effect on SDR. Conventional 2-D flow models can be used to provide accurate head and SDR predictions if satisfying these two criteria.

  4. Analysis of three-dimensional groundwater flow toward a radial collector well in a finite-extent unconfined aquifer

    NASA Astrophysics Data System (ADS)

    Huang, C.-S.; Chen, J.-J.; Yeh, H.-D.

    2015-08-01

    This study develops a three-dimensional mathematical model for describing transient hydraulic head distributions due to pumping at a radial collector well (RCW) in a rectangular confined or unconfined aquifer bounded by two parallel streams and no-flow boundaries. The governing equation with a point-sink term is employed. A first-order free surface equation delineating the water table decline induced by the well is considered. The head solution for the point sink is derived by applying the methods of double-integral transform and Laplace transform. The head solution for a RCW is obtained by integrating the point-sink solution along the laterals of the RCW and then dividing the integration result by the sum of lateral lengths. On the basis of Darcy's law and head distributions along the streams, the solution for the stream depletion rate (SDR) can also be developed. With the aid of the head and SDR solutions, the sensitivity analysis can then be performed to explore the response of the hydraulic head to the change in a specific parameter such as the horizontal and vertical hydraulic conductivities, streambed permeability, specific storage, specific yield, lateral length and well depth. Spatial head distributions subject to the anisotropy of aquifer hydraulic conductivities are analyzed. A quantitative criterion is provided to identify whether groundwater flow at a specific region is 3-D or 2-D without the vertical component. In addition, another criterion is also given to allow the neglect of vertical flow effect on SDR. Conventional 2-D flow models can be used to provide accurate head and SDR predictions if satisfying these two criteria.

  5. Analytical and experimental study of flow through an axial turbine stage with a nonuniform inlet radial temperature profile

    NASA Technical Reports Server (NTRS)

    Schwab, J. R.; Stabe, R. G.; Whitney, W. J.

    1983-01-01

    Results are presented for a typical nonuniform inlet radial temperature profile through an advanced single-stage axial turbine and compared with the results obtained for a uniform profile. Gas temperature rises of 40 K to 95 K are predicted at the hub and tip corners at the trailing edges of the pressure surfaces in both the stator and rotor due to convection of hot fluid from the mean by the secondary flow. The inlet temperature profile is shown to be mixed out at the rotor exit survey plane (2.3 axial chords downstream of the rotor trailing edge) in both the analysis and the experiment. The experimental rotor exit angle profile for the nonuniform inlet temperature profile indicates underturning at the tip caused by increased clearance. Severe underturning also occurs at the mean, both with and without the nonuniform inlet temperature profile. The inviscid rotational flow code used in the analysis fails to predict the underturning at the mean, which may be caused by viscous effects. Previously announced in STAR as N83-27958

  6. Analytical and Experimental Study of Flow Through an Axial Turbine Stage with a Nonuniform Inlet Radial Temperature Profile

    NASA Technical Reports Server (NTRS)

    Schwab, J. R.; Stabe, R. G.; Whitney, W. J.

    1983-01-01

    Results are presented for a typical nonuniform inlet radial temperature profile through an advanced single-stage axial turbine and compared with the results obtained for a uniform profile. Gas temperature rises of 40 K to 95 K are predicted at the hub and tip corners at the trailing edges of the pressure surfaces in both the stator and rotor due to convection of hot fluid from the mean by the secondary flow. The inlet temperature profile is shown to be mixed out at the rotor exit survey plane (2.3 axial chords downstream of the rotor trailing edge) in both the analysis and the experiment. The experimental rotor exit angle profile for the nonuniform inlet temperature profile indicates underturning at the tip caused by increased clearance. Severe underturning also occurs at the mean, both with and without the nonuniform inlet temperature profile. The inviscid rotational flow code used in the analysis fails to predict the underturning at the mean, which may be caused by viscous effects.

  7. Optimal design of high damping force engine mount featuring MR valve structure with both annular and radial flow paths

    NASA Astrophysics Data System (ADS)

    Nguyen, Q. H.; Choi, S. B.; Lee, Y. S.; Han, M. S.

    2013-11-01

    This paper focuses on the optimal design of a compact and high damping force engine mount featuring magnetorheological fluid (MRF). In the mount, a MR valve structure with both annular and radial flows is employed to generate a high damping force. First, the configuration and working principle of the proposed MR mount is introduced. The MRF flows in the mount are then analyzed and the governing equations of the MR mount are derived based on the Bingham plastic behavior of the MRF. An optimal design of the MR mount is then performed to find the optimal structure of the MR valve to generate a maximum damping force with certain design constraints. In addition, the gap size of MRF ducts is empirically chosen considering the ‘lockup’ problem of the mount at high frequency. Performance of the optimized MR mount is then evaluated based on finite element analysis and discussions on performance results of the optimized MR mount are given. The effectiveness of the proposed MR engine mount is demonstrated via computer simulation by presenting damping force and power consumption.

  8. 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

  9. Weak Radial Artery Pulse

    PubMed Central

    Venugopalan, Poothirikovil; Sivakumar, Puthuval; Ardley, Robert G.; Oates, Crispian

    2012-01-01

    We present an 11year-old boy with a weak right radial pulse, and describe the successful application of vascular ultrasound to identify the ulnar artery dominance and a thin right radial artery with below normal Doppler flow velocity that could explain the discrepancy. The implications of identifying this anomaly are discussed. PMID:22375269

  10. Possible evidence for radial flow of heavy mesons in d + Au collisions

    NASA Astrophysics Data System (ADS)

    Sickles, Anne M.

    2014-04-01

    Recent measurements of particle correlations and the spectra of hadrons at both RHIC and the LHC are suggestive of hydrodynamic behavior in very small collision systems (p + Pb, d + Au and possibly high multiplicity p + p collisions at the LHC). The measurements in p + Pb and d + Au collisions are both qualitatively and quantitatively similar to what is seen in heavy ion collisions where low viscosity hot nuclear matter is formed. While light quarks and gluons are thought to make up the bulk matter, one of the most surprising results in heavy ion collisions is that charm quarks also have a large v2. Measurements of the transverse momentum spectra of electrons from the decay of D and B mesons in d + Au collisions show an enhancement in central collisions relative to p + p collisions. We employ the blast-wave model to determine if the flow of heavy quarks in d + Au and p + Pb collisions is able to explain the enhancement observed in the data. We find a reasonable description of the data with blast-wave parameters extracted from fits to the light hadron spectra, suggesting hydrodynamics as a possible explanation.

  11. Redundant vasodilator pathways underlying radial artery flow-mediated dilation are preserved in healthy aging.

    PubMed

    Ballard, Kevin D; Tschakovsky, Michael E; Zaleski, Amanda L; Polk, Donna M; Thompson, Paul D; Kiernan, Francis J; Parker, Beth A

    2014-01-01

    Background. Blocking nitric oxide (NO) and vasodilator prostanoids (PN) does not consistently reduce flow-mediated dilation (FMD) in young adults. The impact of aging on the contribution of NO and PG to FMD is unknown. Methods. FMD was measured in older adults (n = 10, 65 ± 3 y) after arterial infusion of saline, N(G)-monomethyl-L-arginine (L-NMMA), and ketorolac + L-NMMA. Data were compared to published data in young adults. Results. L-NMMA reduced FMD in older adults (8.9 ± 3.6 to 5.9 ± 3.7%) although this was not statistically significant (P = 0.08) and did not differ (P = 0.74) from the reduction observed in young adults (10.0 ± 3.8 to 7.6 ± 4.7%; P = 0.03). Blocking PN did not affect FMD in young or older adults. In older adults, L-NMMA reduced (n = 6; range = 36-123% decrease), augmented (n = 3; 10-122% increase), or did not change FMD (n = 1; 0.4% increase). After PN blockade, FMD responses were reduced (n = 2), augmented (n = 6), or unaffected (n = 1). Conclusions. NO or PN blockade did not consistently reduce FMD in healthy older adults, suggesting the existence of redundant vasodilator phenotypes as observed previously in young adults. PMID:24963406

  12. Redundant Vasodilator Pathways Underlying Radial Artery Flow-Mediated Dilation Are Preserved in Healthy Aging

    PubMed Central

    Ballard, Kevin D.; Tschakovsky, Michael E.; Zaleski, Amanda L.; Polk, Donna M.; Thompson, Paul D.; Kiernan, Francis J.; Parker, Beth A.

    2014-01-01

    Background. Blocking nitric oxide (NO) and vasodilator prostanoids (PN) does not consistently reduce flow-mediated dilation (FMD) in young adults. The impact of aging on the contribution of NO and PG to FMD is unknown. Methods. FMD was measured in older adults (n = 10, 65 ± 3 y) after arterial infusion of saline, N(G)-monomethyl-L-arginine (L-NMMA), and ketorolac + L-NMMA. Data were compared to published data in young adults. Results. L-NMMA reduced FMD in older adults (8.9 ± 3.6 to 5.9 ± 3.7%) although this was not statistically significant (P = 0.08) and did not differ (P = 0.74) from the reduction observed in young adults (10.0 ± 3.8 to 7.6 ± 4.7%; P = 0.03). Blocking PN did not affect FMD in young or older adults. In older adults, L-NMMA reduced (n = 6; range = 36–123% decrease), augmented (n = 3; 10–122% increase), or did not change FMD (n = 1; 0.4% increase). After PN blockade, FMD responses were reduced (n = 2), augmented (n = 6), or unaffected (n = 1). Conclusions. NO or PN blockade did not consistently reduce FMD in healthy older adults, suggesting the existence of redundant vasodilator phenotypes as observed previously in young adults. PMID:24963406

  13. Radial diffusion and penetration of gas molecules and aerosol particles through laminar flow reactors, denuders, and sampling tubes.

    PubMed

    Knopf, Daniel A; Pöschl, Ulrich; Shiraiwa, Manabu

    2015-04-01

    Flow reactors, denuders, and sampling tubes are essential tools for many applications in analytical and physical chemistry and engineering. We derive a new method for determining radial diffusion effects and the penetration or transmission of gas molecules and aerosol particles through cylindrical tubes under laminar flow conditions using explicit analytical equations. In contrast to the traditional Brown method [Brown, R. L. J. Res. Natl. Bur. Stand. (U. S.) 1978, 83, 1-8] and CKD method (Cooney, D. O.; Kim, S. S.; Davis, E. J. Chem. Eng. Sci. 1974, 29, 1731-1738), the new approximation developed in this study (known as the KPS method) does not require interpolation or numerical techniques. The KPS method agrees well with the CKD method under all experimental conditions and also with the Brown method at low Sherwood numbers. At high Sherwood numbers corresponding to high uptake on the wall, flow entry effects become relevant and are considered in the KPS and CKD methods but not in the Brown method. The practical applicability of the KPS method is demonstrated by analysis of measurement data from experimental studies of rapid OH, intermediate NO3, and slow O3 uptake on various organic substrates. The KPS method also allows determination of the penetration of aerosol particles through a tube, using a single equation to cover both the limiting cases of high and low deposition described by Gormley and Kennedy (Proc. R. Ir. Acad., Sect. A. 1949, 52A, 163-169). We demonstrate that the treatment of gas and particle diffusion converges in the KPS method, thus facilitating prediction of diffusional loss and penetration of gases and particles, analysis of chemical kinetics data, and design of fluid reactors, denuders, and sampling lines. PMID:25744622

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

    PubMed

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

    2008-08-01

    The effects of the gas chromatography flow rate on the determination of the deuterium/hydrogen (D/H) ratios of natural gas utilising gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/TC/IRMS) have been evaluated. In general, the measured deltaD values of methane, ethane and propane decrease with increase in column flow rate. When the column flow rate is 1 mL/min or higher, which is commonly used for the determination of D/H ratios of natural gas, the organic H in gas compounds may not be completely converted into hydrogen gas. Based on the results of experiments conducted on a GC column with an i.d. of 0.32 mm, a GC flow rate of 0.6 mL/min is proposed for determining the D/H ratios of natural gas by GC/TC/IRMS. Although this value may be dependent on the instrument conditions used in this work, we believe that correct deltaD values of organic compounds with a few carbon atoms are obtained only when relatively low GC flow rates are used for D/H analysis by GC/TC/IRMS. Moreover, as the presence of trace water could significantly affect the determination of D/H ratios, a newly designed inlet liner was used to remove trace water contained in some gas samples. PMID:18636428

  15. Hydrodynamic chromatography and field flow fractionation in finite aspect ratio channels.

    PubMed

    Shendruk, T N; Slater, G W

    2014-04-25

    Hydrodynamic chromatography (HC) and field-flow fractionation (FFF) separation methods are often performed in 3D rectangular channels, though ideal retention theory assumes 2D systems. Devices are commonly designed with large aspect ratios; however, it can be unavoidable or desirable to design rectangular channels with small or even near-unity aspect ratios. To assess the significance of finite-aspect ratio effects and interpret experimental retention results, an ideal, analytical retention theory is needed. We derive a series solution for the ideal retention ratio of HC and FFF rectangular channels. Rather than limiting devices' ability to resolve samples, our theory predicts that retention curves for normal-mode FFF are well approximated by the infinite plate solution and that the performance of HC is actually improved. These findings suggest that FFF devices need not be designed with large aspect ratios and that rectangular HC channels are optimal when the aspect ratio is unity. PMID:24674643

  16. Microfluidic valve geometries and possibilities for flow switching in gas chromatography

    NASA Astrophysics Data System (ADS)

    Marriott, Philip J.; Eyres, Graham T.; Urban, Sylvia; Rühle, Christian

    2008-12-01

    Classical multi-(two-)dimensional separations in gas chromatography (GC) require switching systems to transfer the gas flow stream from the first to second dimension. This can be accomplished by valve systems, but is more suitably effected by pressure balanced systems, such as the Deans' switch method. Recent developments in microfluidics and related micro-technologies should make gas phase switching much more effective. The capillary flow technology platform of Agilent Technologies is an example of recent developments introduced to GC. Thus various Deans' switch pressure balanced devices, stream splitters, and column couplings bring new capabilities to analytical GC. We are uniquely placed to take advantage of the new devices, owing to our development of advanced operational methods in GC which can make use of microfluidic capillary couplings, and novel cryogenic approaches that deliver performance previously impossible with conventional methods. Multidimensional chromatographic flow switching to isolate pure compounds from complex mixtures suggests many potential applications for enhanced chemical analysis. Multiple dimensions of GC analysis, capabilities for integrating different spectroscopic detection methods for chemical identification of isolated chemical species including mass spectrometry, nuclear magnetic resonance and Fourier transform infrared, can be proposed. Applications in the essential oils and petrochemical area will be outlined.

  17. Mixing characteristics of mixers in flow analysis. Application to two-dimensional detection in ion chromatography.

    PubMed

    Liao, Hongzhu; Dasgupta, Purnendu K; Srinivasan, Kannan; Liu, Yan

    2015-01-01

    Three mixer designs, a back-flow tee mixer (BT), an end-blocked membrane tee mixer (EMT), and a tubular membrane mixer (TM), were fabricated and compared to three commercially available mixers, Visco-Jet Micro mixer (VJM) and HS binary tee mixer with 2 and 10 μL volume (HS-2 and HS-10) mixing cartridges. Internal volumes ranged from 8.3 to 20.3 μL. Performance characteristics were evaluated by the Villermaux-Dushman reaction, noise in baseline conductance upon mixing an electrolyte solution with water, and dispersion/relative dispersion of an injected solute. No single characteristic would uniquely qualify a particular device. In typical postcolumn use when a small reagent flow is added to a principal flow stream using a low-pulsation high-end chromatographic pump, with the worst of these mixers, imperfect mixing accounted for 99.6% of the observed noise. EMT, BT, and TM with asymmetric inlets provided better mixing performances relative to VJM, HS-2, and HS-10 with symmetric inlet ports, especially when the secondary liquid flow rate was much lower than the principal stream-flow rate. Dispersion per unit residence time was singularly large for HS-2. Based on its mixing efficiency and small dispersion, the BT design was found to be the best for practicing postcolumn reaction. As an illustrative application, this was then used to introduce electrogenerated LiOH in a suppressed ion chromatography system to perform sensitive detection of weak acids in a second dimension. PMID:25426864

  18. Receptor-mediated cell attachment and detachment kinetics. II. Experimental model studies with the radial-flow detachment assay.

    PubMed Central

    Cozens-Roberts, C; Quinn, J A; Lauffenburger, D A

    1990-01-01

    Quantitative information regarding the kinetics of receptor-mediated cell adhesion to a ligand-coated surface are crucial for understanding the role of certain key parameters in many physiological and biotechnology-related processes. Here, we use the probabilistic attachment and detachment models developed in the preceding paper to interpret transient data from well-defined experiments. These data are obtained with a simple model cell system that consists of receptor-coated latex beads (prototype cells) and a Radial-Flow Detachment Assay (RFDA) using a ligand-coated glass disc. The receptors and ligands used in this work are complementary antibodies. The beads enable us to examine transient behavior with particles that possess fairly uniform properties that can be varied systematically, and the RFDA is designed for direct observation of adhesion to the ligand-coated glass surface over a range of shear stresses. Our experiments focus on the effects of surface shear stress, receptor density, and ligand density. These data provide a crucial test of the probabilistic framework. We show that these data can be explained with the probabilistic analyses, whereas they cannot be readily interpreted on the basis of a deterministic analysis. In addition, we examine transient data on cell adhesion reported from other assays, demonstrating the consistency of these data with the predictions of the probabilistic models. Images FIGURE 2 PMID:2174272

  19. Hard modeling methods for the curve resolution of data from liquid chromatography with a diode array detector and on-flow liquid chromatography with nuclear magnetic resonance spectroscopy.

    PubMed

    Wasim, Mohammad; Brereton, Richard G

    2006-01-01

    Hard modeling methods have been performed on data from high-performance liquid chromatography with a diode array detector (LC-DAD) and on-flow liquid chromatography with 1H nuclear magnetic spectroscopy (LC-NMR). Four methods have been used to optimize parameters to model concentration profiles, three of which belong to classical optimization methods (the simplex method of Nelder-Mead, sequential quadratic programming approach, and Levenberg-Marquardt method), and the fourth is the application of genetic algorithms using real-value encoding. Only classical methods worked well for LC-DAD data, while all of the methods produced good results when LC-NMR data were divided into small spectral windows of peak clusters and parameters were optimized over each window. PMID:16711734

  20. Post Column Derivatization Using Reaction Flow High Performance Liquid Chromatography Columns.

    PubMed

    Jones, Andrew; Pravadali-Cekic, Sercan; Hua, Stanley; Kocic, Danijela; Camenzuli, Michelle; Dennis, Gary; Shalliker, Andrew

    2016-01-01

    A protocol for the use of reaction flow high performance liquid chromatography columns for methods employing post column derivatization (PCD) is presented. A major difficulty in adapting PCD to modern HPLC systems and columns is the need for large volume reaction coils that enable reagent mixing and then the derivatization reaction to take place. This large post column dead volume leads to band broadening, which results in a loss of observed separation efficiency and indeed detection in sensitivity. In reaction flow post column derivatization (RF-PCD) the derivatization reagent(s) are pumped against the flow of mobile phase into either one or two of the outer ports of the reaction flow column where it is mixed with column effluent inside a frit housed within the column end fitting. This technique allows for more efficient mixing of the column effluent and derivatization reagent(s) meaning that the volume of the reaction loops can be minimized or even eliminated altogether. It has been found that RF-PCD methods perform better than conventional PCD methods in terms of observed separation efficiency and signal to noise ratio. A further advantage of RF-PCD techniques is the ability to monitor effluent coming from the central port in its underivatized state. RF-PCD has currently been trialed on a relatively small range of post column reactions, however, there is currently no reason to suggest that RF-PCD could not be adapted to any existing one or two component (as long as both reagents are added at the same time) post column derivatization reaction. PMID:27168419

  1. A novel micropreconcentrator employing a laminar flow patterned heater for micro gas chromatography

    NASA Astrophysics Data System (ADS)

    Tian, W.-C.; Wu, T. H.; Lu, C.-J.; Chen, W. R.; Sheen, H. J.

    2012-06-01

    A simple micromachined process based on one photomask is developed for a novel micropreconcentrator (µPCT) used in a micro gas chromatograph (µGC). Unique thick silver heating microstructures with a high surface area for microheater of µPCT are fabricated by combining the microfluidic laminar flow technique and the Tollens’ reaction within a microchannel. Silver deposition using this laminar flow patterning technique provides a higher deposition rate and easier microfabrication compared to conventional micromachined technologies for thick metal microstructures (>200 µm). An amorphous and porous carbon film that functions as an adsorbent is grown on microheaters inside the microchannel. The µPCT can be heated to >300 °C rapidly by applying a constant electrical power of ˜1 W with a heating rate of 10 °C s-1. Four volatile organic compounds, acetone, benzene, toluene and xylene, are collected through the proposed novel µPCTs and separated successfully using a 17 m long gas chromatography column. The peak widths at half height (PWHHs) of the four compounds are relatively narrow (<6 s), and the minimum PWHH of 3.75 s is obtained for acetone. The preconcentration factors are >38 000 for benzene and toluene.

  2. Spatial analysis of aquifer response times for radial flow processes: Nondimensional analysis and laboratory-scale tests

    NASA Astrophysics Data System (ADS)

    Jazaei, Farhad; Simpson, Matthew J.; Clement, T. Prabhakar

    2016-01-01

    A fundamental concept in groundwater hydrology is the notion of steady state, or equilibrium conditions. When a system at some initial steady state condition is perturbed by pumping, a transient cone of depression will develop and the system will approach a new steady state condition. Understanding the time scale required for the transient process to occur is of practical interest since it would help practitioners decide whether to use a steady state model or a more complicated transient model. Standard approaches to estimate the response time use simple scaling relationships which neglect spatial variations. Alternatively, others define the response time to be the amount of time taken for the difference between the transient and steady state solutions to fall below some arbitrary tolerance level. Here, we present a novel approach and use the concept of mean action time to predict aquifer response time scales in a two-dimensional radial geometry for pumping, injection and recovery processes. Our approach leads to relatively simple closed form expressions that explicitly show how the time scale depends on the hydraulic parameters and position. Furthermore, our dimensionless framework allows us to predict the response time scales for a range of applications including small scale laboratory problems and large scale field problems. Our analysis shows that the response time scales vary spatially, but are equivalent for pumping, injection and associated recovery processes. Furthermore, the time scale is independent of the pumping or injection flow rate. We test these predictions in a laboratory scale aquifer and find that our physical measurements corroborate the theoretical predictions.

  3. Impact of higher alginate expression on deposition of Pseudomonas aeruginosa in radial stagnation point flow and reverse osmosis systems.

    PubMed

    Herzberg, Moshe; Rezene, Tesfalem Zere; Ziemba, Christopher; Gillor, Osnat; Mathee, Kalai

    2009-10-01

    Extracellular polymeric substances (EPS) have major impact on biofouling of reverse osmosis (RO) membranes. On one hand, EPS can reduce membrane permeability and on the other, EPS production by the primary colonizers may influence their deposition and attachment rate and subsequently affect the biofouling propensity of the membrane. The role of bacterial exopolysaccharides in bacterial deposition followed by the biofouling potential of an RO membrane was evaluated using an alginate overproducing (mucoid) Pseudomonas aeruginosa. The mucoid P. aeruginosa PAOmucA22 was compared with its isogenic nonmucoid prototypic parent PAO1 microscopically in a radial stagnation point flow (RSPF) system for their bacterial deposition characteristics. Then, biofouling potential of PAO1 and PAOmucA22 was determined in a crossflow rectangular plate-and-frame membrane cell, in which the strains were cultivated on a thin-film composite, polyamide, flat RO membrane coupon (LFC-1) under laminar flow conditions. In the RSPF system, the observed deposition rate of the mucoid strain was between 5- and 10-fold lower than of the wild type using either synthetic wastewater medium (with ionic strength of 14.7 mM and pH 7.4) or 15 mM KCl solution (pH of 6.2). The slower deposition rate of the mucoid strain is explained by 5- to 25-fold increased hydrophilicity of the mucoid strain as compared to the isogenic wild type, PAO1. Corroborating with these results, a significant delay in the onset of biofouling of the RO membrane was observed when the mucoid strain was used as the membrane colonizer, in which the observed time for the induced permeate flux decline was delayed (ca. 2-fold). In conclusion, the lower initial cell attachment of the mucoid strain decelerated biofouling of the RO membrane. Bacterial deposition and attachment is a critical step in biofilm formation and governed by intimate interactions between outer membrane proteins of the bacteria and the surface. Shielding these

  4. Reducing NO(x) emissions from a nitric acid plant of domestic petrochemical complex: enhanced conversion in conventional radial-flow reactor of selective catalytic reduction process.

    PubMed

    Abbasfard, Hamed; Hashemi, Seyed Hamid; Rahimpour, Mohammad Reza; Jokar, Seyyed Mohammad; Ghader, Sattar

    2013-01-01

    The nitric acid plant of a domestic petrochemical complex is designed to annually produce 56,400 metric tons (based on 100% nitric acid). In the present work, radial-flow spherical bed reactor (RFSBR) for selective catalytic reduction of nitric oxides (NO(x)) from the stack of this plant was modelled and compared with the conventional radial-flow reactor (CRFR). Moreover, the proficiency of a radial-flow (water or nitrogen) membrane reactor was also compared with the CRFR which was found to be inefficient at identical process conditions. In the RFSBR, the space between the two concentric spheres is filled by a catalyst. A mathematical model, including conservation of mass has been developed to investigate the performance of the configurations. The model was checked against the CRFR in a nitric acid plant located at the domestic petrochemical complex. A good agreement was observed between the modelling results and the plant data. The effects of some important parameters such as pressure and temperature on NO(x) conversion were analysed. Results show 14% decrease in NO(x) emission annually in RFSBR compared with the CRFR, which is beneficial for the prevention of NO(x) emission, global warming and acid rain. PMID:24527652

  5. Fully automated screening of veterinary drugs in milk by turbulent flow chromatography and tandem mass spectrometry

    PubMed Central

    Stolker, Alida A. M.; Peters, Ruud J. B.; Zuiderent, Richard; DiBussolo, Joseph M.

    2010-01-01

    There is an increasing interest in screening methods for quick and sensitive analysis of various classes of veterinary drugs with limited sample pre-treatment. Turbulent flow chromatography in combination with tandem mass spectrometry has been applied for the first time as an efficient screening method in routine analysis of milk samples. Eight veterinary drugs, belonging to seven different classes were selected for this study. After developing and optimising the method, parameters such as linearity, repeatability, matrix effects and carry-over were studied. The screening method was then tested in the routine analysis of 12 raw milk samples. Even without internal standards, the linearity of the method was found to be good in the concentration range of 50 to 500 µg/L. Regarding repeatability, RSDs below 12% were obtained for all analytes, with only a few exceptions. The limits of detection were between 0.1 and 5.2 µg/L, far below the maximum residue levels for milk set by the EU regulations. While matrix effects—ion suppression or enhancement—are obtained for all the analytes the method has proved to be useful for screening purposes because of its sensitivity, linearity and repeatability. Furthermore, when performing the routine analysis of the raw milk samples, no false positive or negative results were obtained. PMID:20379812

  6. Determination of urinary glucose by a flow injection analysis amperometric biosensor and ion-exchange chromatography.

    PubMed

    Male, K B; Luong, J H

    1992-12-01

    A practical biosensor system has been developed for the determination of urinary glucose using a flow-injection analysis (FIA) amperometric detector and ion-exchange chromatography. Glucose oxidase was immobilized onto porous aminopropyl glass beads via glutaraldehyde activation to form an immobilized enzyme column. On the basis of its negative charge at pH 5.5, endogenous urate in urine samples was effectively retained by an upstream anion-exchange resin column. The biosensor system possessed a sensitivity of 160 +/- 2.4 RU microM-1 (RU or relative unit is defined as 2.86 microV at the detection output) for glucose with a minimum detection level of 10 microM. When applied for the determination of urinary glucose, the result obtained compared very well with that of the widely accepted hexokinase assay. The immobilized glucose oxidase could be reused for more than 1000 repeated analyses without losing its original activity. The reuse of the acetate anion-exchange column before replacement would be about 25-30 analyses. Acetaminophen and ascorbic acid were also effectively adsorbed by the acetate anion exchanger. The introduction of this type of anion exchanger thus greatly improved the selectivity of the FIA biosensor system and fostered its applicability for the determination of glucose in urine samples. PMID:1303063

  7. Selective and Sensitive Chemiluminescence Determination of MCPB: Flow Injection and Liquid Chromatography.

    PubMed

    Meseguer-Lloret, Susana; Torres-Cartas, Sagrario; Catalá-Icardo, Mónica; Gómez-Benito, Carmen

    2016-02-01

    Two new chemiluminescence (CL) methods are described for the determination of the herbicide 4-(4-chloro-o-tolyloxy) butyric acid (MCPB). First, a flow injection chemiluminescence (FI-CL) method is proposed. In this method, MCPB is photodegraded with an ultraviolet (UV) lamp and the photoproducts formed provide a great CL signal when they react with ferricyanide in basic medium. Second, a high-performance liquid chromatography chemiluminescence (HPLC-CL) method is proposed. In this method, before the photodegradation and CL reaction, the MCPB and other phenoxyacid herbicides are separated in a C18 column. The experimental conditions for the FI-CL and HPLC-CL methods are optimized. Both methods present good sensitivity, the detection limits being 0.12 µg L(-1) and 0.1 µg L(-1) (for FI-CL and HPLC-CL, respectively) when solid phase extraction (SPE) is applied. Intra- and interday relative standard deviations are below 9.9%. The methods have been satisfactorily applied to the analysis of natural water samples. FI-CL method can be employed for the determination of MCPB in simple water samples and for the screening of complex water samples in a fast, economic, and simple way. The HPLC-CL method is more selective, and allows samples that have not been resolved with the FI-CL method to be solved. PMID:26903566

  8. A flexible loop-type flow modulator for comprehensive two-dimensional gas chromatography.

    PubMed

    Tranchida, Peter Quinto; Purcaro, Giorgia; Visco, Alessandro; Conte, Lanfranco; Dugo, Paola; Dawes, Peter; Mondello, Luigi

    2011-05-27

    The present investigation is focused on a simple flow modulator (FM), for comprehensive two-dimensional gas chromatography (GC×GC). The interface is stable at high temperatures, and consists of a metallic disc (located inside the GC oven) with seven ports, which are connected to an auxiliary pressure source via two branches, to the first and second dimension, to a waste branch (linked to a needle valve) and to an exchangeable modulation loop (2 ports). The ports are connected via micro-channels, etched on one of the inner surfaces of the disc. Modulation is achieved using a two-way electrovalve, connected on one side to the additional pressure source, and to the two metal branches, on the other. An FM enantio-GC×polar-GC method (using a flame ionization detector) was optimized (a 40-μL loop was employed), for the analysis of essential oils. As an example, an application on spearmint oil is shown; the method herein proposed was subjected to validation. Finally, an FM GC×GC diesel experiment was carried out, using an apolar-polar column combination, to demonstrate the effectiveness of the modulator in the analysis of a totally different sample-type. PMID:21256493

  9. The solution-adaptive numerical simulation of the 3D viscous flow in the serpentine coolant passage of a radial inflow turbine blade

    NASA Astrophysics Data System (ADS)

    Dawes, W. N.

    1992-06-01

    This paper describes the application of a solution-adaptive, three-dimensional Navier-Stokes solver to the problem of the flow in turbine internal coolant passages. First the variation of Nusselt number in a cylindrical, multi-ribbed duct is predicted and found to be in acceptable agreement with experimental data. Then the flow is computed in the serpentine coolant passage of a radial inflow turbine including modeling the internal baffles and pin fins. The aerodynamics of the passage, particularly that associated with the pin fins, is found to be complex. The predicted heat transfer coefficients allow zones of poor coolant penetration and potential hot spots to be identified.

  10. Differences in the Properties of the Radial Artery between Cun, Guan, Chi, and Nearby Segments Using Ultrasonographic Imaging: A Pilot Study on Arterial Depth, Diameter, and Blood Flow

    PubMed Central

    Kim, Jaeuk U.; Lee, Yu Jung; Kim, Jong Yeol

    2015-01-01

    Aim of the Study. The three conventional pulse-diagnostic palpation locations (PLs) on both wrists are Cun, Guan, and Chi, and each location reveals different clinical information. To identify anatomical or hemodynamic specificity, we used ultrasonographic imaging to determine the arterial diameter, radial artery depth, and arterial blood flow velocity at the three PLs and at nearby non-PL segments. Methods. We applied an ultrasound scanner to 44 subjects and studied the changes in the arterial diameter and depth as well as in the average/maximum blood flow velocities along the radial artery at three PLs and three non-PLs located more proximally than Chi. Results. All of the measurements at all of the PLs were significantly different (P < 0.01). Artery depth was significantly different among the non-PLs; however, this difference became insignificant after normalization to the arm circumference. Conclusions. Substantial changes in the hemodynamic and anatomical properties of the radial artery around the three PLs were insignificant at the nearby non-PLs segments. This finding may provide a partial explanation for the diagnostic use of “Cun, Guan, and Chi.” PMID:25763090

  11. Home-made online hyphenation of pressurized liquid extraction, turbulent flow chromatography, and high performance liquid chromatography, Cistanche deserticola as a case study.

    PubMed

    Song, Qingqing; Li, Jun; Liu, Xiao; Zhang, Yuan; Guo, Liping; Jiang, Yong; Song, Yuelin; Tu, Pengfei

    2016-03-18

    Incompatibility between the conventional pressurized liquid extraction (PLE) devices and high performance liquid chromatography (HPLC) extensively hinders direct and green chemical analysis of herbal materials. Herein, a facile PLE module was configured, and then it was online hyphenated with HPLC via a turbulent flow chromatography (TFC) column. Regarding PLE module, a long PEEK tube (0.13 × 1000 mm) was employed to generate desired pressure (approximately 13.0 MPa) when warm acidic water (70 °C) was delivered as extraction solvent at a high flow rate (2.5 mL/min), and a hollow guard column (3.0 × 4.0 mm) was implemented to hold crude materials. Effluent was collected from the outlet of PEEK tube, concentrated, and subjected onto HPLC coupled with hybrid ion trap-time of flight mass spectrometer to assess the extraction efficiency and also to profile the chemical composition of Cistanche deserticola (CD) that is honored as "Ginseng of the desert". Afterwards, a TFC column was introduced to accomplish online transmission of low molecule weight components from PLE module to HPLC coupled with diode array detection, and two electronic 6-port/2-channel valves were in charge of alternating the whole system between extraction (0-3.0 min) and elution (3.0-35.0 min) phases. Quantitative method was developed and validated for simultaneous determination of eight primary phenylethanoid glycosides in CD using online PLE-TFC-HPLC. All findings demonstrated that the home-made platform is advantageous at direct chemical analysis, as well as time-, solvent-, and material-savings, suggesting a robust tool for chemical fingerprinting of herbs. PMID:26896915

  12. Liquid chromatography mass spectrometry determination of perfluoroalkyl acids in environmental solid extracts after phospholipid removal and on-line turbulent flow chromatography purification.

    PubMed

    Mazzoni, M; Polesello, S; Rusconi, M; Valsecchi, S

    2016-07-01

    An on-line TFC (Turbulent Flow Chromatography) clean up procedures coupled with UHPLC-MS/MS (Ultra High Performance Liquid Chromatography Mass Spectrometry) multi-residue method was developed for the simultaneous determination of 8 perfluroalkyl carboxylic acids (PFCA, from 5 to 12 carbon atoms) and 3 perfluoroalkyl sulfonic acids (PFSA, from 4 to 8 carbon atoms) in environmental solid matrices. Fast sample preparation procedure was based on a sonication-assisted extraction with acetonitrile. Phospholipids in biological samples were fully removed by an off-line SPE purification before injection, using HybridSPE(®) Phospholipid Ultra cartridges. The development of the on-line TFC clean-up procedure regarded the choice of the stationary phase, the optimization of the mobile phase composition, flow rate and injected volume. The validation of the optimized method included the evaluation of matrix effects, accuracy and reproducibility. Signal suppression in the analysis of fortified extracts ranged from 1 to 60%, and this problem was overcome by using isotopic dilution. Since no certified reference materials were available for PFAS in these matrices, accuracy was evaluated by recoveries on spiked clam samples which were 98-133% for PFCAs and 40-60% for PFSAs. MLDs and MLQs ranged from 0.03 to 0.3ngg(-1) wet weight and from 0.1 to 0.9ngg(-1) wet weight respectively. Repeatability (intra-day precision) and reproducibility (inter-day precision) showed RSD from 3 to 13% and from 4 to 27% respectively. Validated on-line TFC/UHPLC-MS/MS method has been applied for the determination of perfluoroalkyl acids in different solid matrices (sediment, fish, bivalves and bird yolk). PMID:27237594

  13. Purification of Hemoglobin from Red Blood Cells using Tangential Flow Filtration and Immobilized Metal Ion Affinity Chromatography

    PubMed Central

    Elmer, Jacob; Harris, David; Palmer, Andre F.

    2011-01-01

    Two methods for purifying hemoglobin (Hb) from red blood cells (RBCs) are examined and compared. In the first method, red blood cell lysate is clarified with a 50 nm tangential flow filter and hemoglobin is purified using immobilized metal ion affinity chromatography (IMAC). In the second method, RBC lysate is processed with 50 nm, 500 kDa, and 50-100 kDa tangential flow filters, then hemoglobin is purified with IMAC. Our results show that the hemoglobins from both processes produce identical Hb products that are ultrapure and retain their biophysical properties (except for chicken hemoglobin, which shows erratic oxygen binding behavior after purification). Therefore, the most efficient method for Hb purification appears to be clarification with a 50 nm tangential flow filter, followed by purification with IMAC, and sample concentration/polishing on a 10-50 kDa tangential flow filter. PMID:21195679

  14. Determination of Flow Rates in Capillary Liquid Chromatography Coupled to a Nanoelectrospray Source using Droplet Image Analysis Software.

    PubMed

    Cohen, Alejandro M; Soto, Axel J; Fawcett, James P

    2016-08-01

    Liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS/MS) is widely used in proteomic and metabolomic workflows. Considerable analytical improvements have been observed when the components of LC systems are scaled down. Currently, nano-ESI is typically done at capillary LC flow rates ranging from 200 to 300 nL/min. At these flow rates, trouble shooting and leak detection of LC systems has become increasingly challenging. In this paper we present a novel proof-of-concept approach to measure flow rates at the tip of electrospray emitters when the ionization voltage is turned off. This was achieved by estimating the changes in the droplet volume over time using digital image analysis. The results are comparable with the traditional methods of measuring flow rates, with the potential advantages of being fully automatable and nondisruptive. PMID:27351615

  15. MEASUREMENT OF RADIONUCLIDES USING ION CHROMATOGRAPHY AND FLOW-CELL SCINTILLATION COUNTING WITH PULSE SHAPE DISCRIMINATION

    SciTech Connect

    R. A. Fjeld; T.A. DeVol; J.D. Leyba

    2000-03-30

    Radiological characterization and monitoring is an important component of environmental management activities throughout the Department of Energy complex. Gamma-ray spectroscopy is the technology most often used for the detection of radionuclides. However, radionuclides which cannot easily be detected by gamma-ray spectroscopy, such as pure beta emitters and transuranics, pose special problems because their quantification generally requires labor intensive radiochemical separations procedures that are time consuming and impractical for field applications. This project focused on a technology for measuring transuranics and pure beta emitters relatively quickly and has the potential of being field deployable. The technology combines ion exchange liquid chromatography and on-line alpha/beta pulse shape discriminating scintillation counting to produce simultaneous alpha and beta chromatograms. The basic instrumentation upon which the project was based was purchased in the early 1990's. In its original commercial form, the instrumentation was capable of separating select activation/fission products in ionic forms from relatively pure aqueous samples. We subsequently developed the capability of separating and detecting actinides (thorium, uranium, neptunium, plutonium, americium, and curium) in less than 30 minutes (Reboul, 1993) and realized that the potential time savings over traditional radiochemical methods for isolating some of these radionuclides was significant. However, at that time, the technique had only been used for radionuclide concentrations that were considerably above environmental levels and for aqueous samples of relatively high chemical purity. For the technique to be useful in environmental applications, development work was needed in lowering detection limits; to be useful in applications involving non-aqueous matrices such as soils and sludges or complex aqueous matrices such as those encountered in waste samples, development work was needed in

  16. Two-dimensional turbulent flow chromatography coupled on-line to liquid chromatography-mass spectrometry for solution-based ligand screening against multiple proteins.

    PubMed

    Zhou, Jian-Liang; An, Jing-Jing; Li, Ping; Li, Hui-Jun; Jiang, Yan; Cheng, Jie-Fei

    2009-03-20

    We present herein a novel bioseparation/chemical analysis strategy for protein-ligand screening and affinity ranking in compound mixtures, designed to increase screening rates and improve sensitivity and ruggedness in performance. The strategy is carried out by combining on-line two-dimensional turbulent flow chromatography (2D-TFC) with liquid chromatography-mass spectrometry (LC-MS), and accomplished through the following steps: (1) a reversed-phase TFC stage to separate the protein/ligand complex from the unbound free molecules, (2) an on-line dissociation process to release the bound ligands from the complexes, and (3) a second mixed-mode cation-exchange/reversed-phase TFC stage to trap the bound ligands and to remove the proteins and salts, followed by LC-MS analysis for identification and determination of the binding affinities. The technique can implement an ultra-fast isolation of protein/ligand complex with the retention time of a complex peak in about 5s, and on-line prepare the "clean" sample to be directly compatible with the LC-MS analysis. The improvement in performance of this 2D-TFC/LC-MS approach over the conventional approach has been demonstrated by determining affinity-selected ligands of the target proteins acetylcholinesterase and butyrylcholinesterase from a small library with known binding affinities and a steroidal alkaloid library composed of structurally similar compounds. Our results show that 2D-TFC/LC-MS is a generic and efficient tool for high-throughput screening of ligands with low-to-high binding affinities, and structure-activity relationship evaluation. PMID:19203758

  17. Analysis of endocrine disrupters and related compounds in sediments and sewage sludge using on-line turbulent flow chromatography-liquid chromatography-tandem mass spectrometry.

    PubMed

    Gorga, Marina; Insa, Sara; Petrovic, Mira; Barceló, Damià

    2014-07-25

    A novel fully automated method based on dual column switching using turbulent flow chromatography followed by liquid chromatography coupled to tandem mass spectrometry (TFC-LC-MS/MS) was applied for the determination of endocrine disruptors (EDCs) and related compounds in sediment and sewage sludge samples. This method allows the unequivocal identification and quantification of the most relevant environmental EDCs such as natural and synthetic estrogens and their conjugates, antimicrobials, parabens, bisphenol A (BPA), alkylphenolic compounds, benzotriazoles, and organophosphorus flame retardants, minimizing time of analysis and alleviating matrix effects. Applying this technique, after the extraction of the target compounds by pressurized liquid extraction (PLE), sediment and sewage sludge extracts were directly injected to the chromatographic system and the analytes were concentrated into the clean-up loading column. Using six-port switching system, the analytes were transferred to the analytical column for subsequent detection by MS-MS (QqQ). In order to optimize this multiplexing system, a comparative study employing six types of TurboFlow™ columns, with different chemical modifications, was performed to achieve the maximum retention of analytes and best elimination of matrix components. Using the optimized protocol low limits of quantification (LOQs) were obtained ranging from 0.0083 to 1.6 ng/g for sediment samples and from 0.10 to 125 ng/g for sewage sludge samples (except for alkylphenol monoethoxylate). The method was used to evaluate the presence and fate of target EDCs in the Ebro River which is the most important river in Spain with intensive agricultural and industrial activities in the basin that contribute to deteriorating soil and water quality. PMID:24909438

  18. Influence of heat and mass transfer, initial stress and radially varying magnetic field on the peristaltic flow in an annulus with gravity field

    NASA Astrophysics Data System (ADS)

    Abd-Alla, A. M.; Abo-Dahab, S. M.; El-Shahrany, H. D.

    2014-08-01

    In this paper, the effects of both initial stress, radially varying and gravity field on the peristaltic flow of an incompressible MHD Newtonian fluid in a vertical annulus have been studied under the assumption of long wavelength and low-Reynolds number. The analytical solution has been derived for the temperature, concentration and velocity. The results for velocity, concentration and temperature obtained in the analytical form have been evaluated numerically and discussed briefly. The effect of the non-dimensional wave amplitude, the coefficient of viscosity, Sort number, Schmidt number, initial stress, gravitational field and the dimensionless time-mean flow in the wave frame are analyzed theoretically and computed numerically. The expressions for pressure rise, temperature, concentration field, velocity and pressure gradient are sketched for various embedded parameters and interpreted. Numerical results are given and illustrated graphically in each case considered. Comparison was made with the results obtained in the presence and absence of initial stress and gravitational field.

  19. Application of a quasi-3D inviscid flow and boundary layer analysis to the hub-shroud contouring of a radial turbine

    NASA Technical Reports Server (NTRS)

    Civinskas, K. C.; Povinelli, L. A.

    1984-01-01

    Application of a quasi-3D approach to the aerodynamic analysis of several radial turbine configurations is described. The objective was to improve the rotor aerodynamic characteristics by hub-shroud contouring. The approach relies on available 2D inviscid methods coupled with boundary layer analysis to calculate profile, mixing, and endwall losses. Windage, tip clearance, incidence, and secondary flow losses are estimated from correlations. To eliminate separation along the hub and blade suction surfaces of a baseline rotor, the analysis was also applied to three alternate hub-shroud geometries. Emphasis was on elimination an inducer velocity overshoot as well as increasing hub velocities. While separation was never eliminated, the extent of the separated area was progressively reduced. Results are presented in terms of mid-channel and blade surface velocities; kinetic energy loss coefficients; and efficiency. The calculation demonstrates a first step for a systematic approach to radial turbine design that can be used to identify and control aerodynamic characteristics that ultimately determine heat transfer and component life. Experimentation will be required to assess the extent to which flow and boundary layer behavior were predicted correctly.

  20. Packing of large-scale chromatography columns with irregularly shaped glass based resins using a stop-flow method

    PubMed Central

    Siu, Sun Chau; Chia, Celeste; Mok, Yanglin; Pattnaik, Priyabrata

    2014-01-01

    Rigid chromatography resins, such as controlled pore glass based adsorbents, offer the advantage of high permeability and a linear pressure-flow relationship irrespective of column diameter which improves process time and maximizes productivity. However, the rigidity and irregularly shaped nature of these resins often present challenges in achieving consistent and uniform packed beds as formation of bridges between resin particles can hinder bed consolidation. The standard flow-pack method when applied to irregularly shaped particles does not yield well-consolidated packed beds, resulting in formation of a head space and increased band broadening during operation. Vibration packing methods requiring the use of pneumatically driven vibrators are recommended to achieve full packed bed consolidation but limitations in manufacturing facilities and equipment may prevent the implementation of such devices. The stop-flow packing method was developed as an improvement over the flow-pack method to overcome these limitations and to improve bed consolidation without the use of vibrating devices. Transition analysis of large-scale columns packed using the stop-flow method over multiple cycles has shown a two- to three-fold reduction of change in bed integrity values as compared to a flow-packed bed demonstrating an improvement in packed bed stability in terms of the height equivalent to a theoretical plate (HETP) and peak asymmetry (As). PMID:25080096

  1. Packing of large-scale chromatography columns with irregularly shaped glass based resins using a stop-flow method.

    PubMed

    Siu, Sun Chau; Chia, Celeste; Mok, Yanglin; Pattnaik, Priyabrata

    2014-01-01

    Rigid chromatography resins, such as controlled pore glass based adsorbents, offer the advantage of high permeability and a linear pressure-flow relationship irrespective of column diameter which improves process time and maximizes productivity. However, the rigidity and irregularly shaped nature of these resins often present challenges in achieving consistent and uniform packed beds as formation of bridges between resin particles can hinder bed consolidation. The standard flow-pack method when applied to irregularly shaped particles does not yield well-consolidated packed beds, resulting in formation of a head space and increased band broadening during operation. Vibration packing methods requiring the use of pneumatically driven vibrators are recommended to achieve full packed bed consolidation but limitations in manufacturing facilities and equipment may prevent the implementation of such devices. The stop-flow packing method was developed as an improvement over the flow-pack method to overcome these limitations and to improve bed consolidation without the use of vibrating devices. Transition analysis of large-scale columns packed using the stop-flow method over multiple cycles has shown a two- to three-fold reduction of change in bed integrity values as compared to a flow-packed bed demonstrating an improvement in packed bed stability in terms of the height equivalent to a theoretical plate (HETP) and peak asymmetry (As ). PMID:25080096

  2. Minimizing ultraviolet noise due to mis-matches between detector flow cell and post column mobile phase temperatures in supercritical fluid chromatography: effect of flow cell design.

    PubMed

    Berger, Terry A

    2014-10-17

    A mis-match between the post-column mobile phase temperature and the UV detector flow cell temperature can cause significant UV noise in supercritical fluid chromatography (SFC). Deviations as little as 5 °C can increase noise as much as 5 times, making the detector unsuited for trace analysis. Two approaches were used to minimize this noise. When a flow cell was in direct thermal contact (metal on metal) with the detector optical bench, the mobile phase temperature was actively controlled to the measured flow cell temperature, by using one of the heat exchangers (HX) in the column compartment. However, with some older, but still widely used flow cell designs, this required repeated, hourly monitoring of the flow cell temperature and repeated manual adjustment of the heat exchanger temperature, due to thermal drift. Flow cell design had a strong influence on susceptibility to this thermally induced noise. Thermally insulating the flow cell from the optical bench made some cells much less susceptible to such thermally induced noise. Five different flow cells, some insulated, some un-insulated, were evaluated. Most had a truncated conical flow path, but one had a cylindrical flow path. Using either approach, the ASTM noise, with a 10mm, 13 μL conical flow cell, could be optimized to ≈0.007 mAU at 2.5 Hz, in SFC, which is very near the 0.006 mAU manufacturer's specification for HPLC. The insulated version of this flow cell required far less optimization, compared to the un-insulated version. At 150 bar, an experimental 3mm, 2 μL flow cell, with only one side insulated, yielded noise slightly too high (≈0.16-0.18 mAU) for trace analysis, at 80 Hz. However, at 200 bar, noise at 80 Hz was <0.06 mAU, which should allow quantification of a 1 mAU tall trace component with a signal to noise ratio (S/N) >10. Even partially un-insulated, this flow cell design was much less susceptible to thermally induced noise. Further insulating this flow cell design failed to improve

  3. Transient radial flow to a well in an unconfined aquifer. Part 1, An evaluation of some conceptual methods

    SciTech Connect

    Narasimhan, T.N.; Zhu, Ming

    1991-08-01

    The analytic solutions of Boulton (1954) and Neuman (1972) for transient flow to a well in an unconfined aquifer are based on the assumption that the role of the unsaturated zone can be adequately accounted for by restricting attention to the release of water from the zone through which the water table moves. Both researchers mathematically treat this released water as a time-dependent source term. The differences between the models of Boulton and Neuman are that the former neglects vertical components of flow in the aquifer, but allows for an exponential process for the release of water as a function of time, whereas the latter assumes instantaneous release from storage, but accounts for vertical components of flow. Given this set of assumptions, we examine the applicability of these two methods using a general purpose numerical model through a process of verification extension and comparison. The issues addressed include: the role of well-bore storage in masking intermediate-time behavior, combined effects of exponential release as well as vertical flow, logic for vertical averaging of drawdowns, and the sensitivity of system response to the magnitude of specific yield. The issue of how good the assumptions of Boulton and Neuman are in the context of the general theory of unsaturated flow is addressed in part 2 of this two-part series of reports.

  4. MHD flow and heat transfer of a viscous fluid over a radially stretching power-law sheet with suction/injection in a porous medium

    NASA Astrophysics Data System (ADS)

    Khan, M.; Munir, A.; Shahzad, A.; Shah, A.

    2015-03-01

    A steady boundary layer flow and heat transfer over a radially stretching isothermal porous sheet is analyzed. Stretching is assumed to follow a radial power law, and the fluid is electrically conducting in the presence of a transverse magnetic field with a very small magnetic Reynolds number. The governing nonlinear partial differential equations are reduced to a system of nonlinear ordinary differential equations by using appropriate similarity transformations, which are solved analytically by the homotopy analysis method (HAM) and numerically by employing the shooting method with the adaptive Runge-Kutta method and Broyden's method in the domain [0,∞). Analytical expressions for the velocity and temperature fields are derived. The influence of pertinent parameters on the velocity and temperature profiles is discussed in detail. The skin friction coefficient and the local Nusselt number are calculated as functions of several influential parameters. The results predicted by both methods are demonstrated to be in excellent agreement. Moreover, HAM results for a particular problem are also compared with exact solutions.

  5. Improvement in Accuracy of Ultrasonic Measurement of Transient Change in Viscoelasticity of Radial Arterial Wall Due to Flow-Mediated Dilation by Adaptive Low-Pass Filtering

    NASA Astrophysics Data System (ADS)

    Ikeshita, Kazuki; Hasegawa, Hideyuki; Kanai, Hiroshi

    2012-07-01

    In our previous study, the stress-strain relationship of the radial arterial wall was measured and the viscoelasticity of the intima-media region was estimated from the stress-strain relationship. Furthermore, the transient change in viscoelasticity due to flow-mediated dilation (FMD) was estimated by the automated detection of wall boundaries. In the present study, the strain rate was adaptively filtered to improve the accuracy of viscoelasticity estimation by decreasing the high-frequency noise. Additionally, in a basic experiment, this method was validated using a silicone tube (simulating artery). In the basic experiment, the elasticity was estimated with a mean error of 1.2%. The elasticity measured at each beam position was highly reproducible among measurements, whereas there was a slight variation in measured elasticity among beams. Consequently, in in vivo measurements, the normalized mean square error (MSE) was clearly decreased. Additionally, the stress-strain relationship of the radial arterial wall was obtained and the viscoelasticity was estimated accurately. The inner small loop, which corresponds to the negative pressure wave caused by the closure of the aortic valve, can be observed using the adaptive low-pass filtering (LPF). Moreover, the transient changes in these parameters were similar to those in the previous study. These results show the potential of the proposed method for the thorough analysis of the transient change in viscoelasticity due to FMD.

  6. Radial lean direct injection burner

    DOEpatents

    Khan, Abdul Rafey; Kraemer, Gilbert Otto; Stevenson, Christian Xavier

    2012-09-04

    A burner for use in a gas turbine engine includes a burner tube having an inlet end and an outlet end; a plurality of air passages extending axially in the burner tube configured to convey air flows from the inlet end to the outlet end; a plurality of fuel passages extending axially along the burner tube and spaced around the plurality of air passage configured to convey fuel from the inlet end to the outlet end; and a radial air swirler provided at the outlet end configured to direct the air flows radially toward the outlet end and impart swirl to the air flows. The radial air swirler includes a plurality of vanes to direct and swirl the air flows and an end plate. The end plate includes a plurality of fuel injection holes to inject the fuel radially into the swirling air flows. A method of mixing air and fuel in a burner of a gas turbine is also provided. The burner includes a burner tube including an inlet end, an outlet end, a plurality of axial air passages, and a plurality of axial fuel passages. The method includes introducing an air flow into the air passages at the inlet end; introducing a fuel into fuel passages; swirling the air flow at the outlet end; and radially injecting the fuel into the swirling air flow.

  7. ANALYTICAL APPROXIMATION OF THE BIODEGRADATION RATE FOR IN SITU BIOREMEDIATION OF GROUNDWATER UNDER IDEAL RADIAL FLOW CONDITIONS. (R824785)

    EPA Science Inventory

    We derive the long-term biodegradation rate of an organic contaminant (substrate) for an in situ bioremediation model with axisymmetric flow conditions. The model presumes that a nonsorbing electron acceptor is injected into a saturated homogeneous porous medium which initially c...

  8. The effects of the secondary fluid temperature on the energy transfer in an unsteady ejector with a radial-flow diffuser

    NASA Astrophysics Data System (ADS)

    Ababneh, Amer Khalil; Jawarneh, Ali M.; Tlilan, Hitham M.; Ababneh, Mohammad K.

    2009-11-01

    Unsteady ejectors are devices whereby energy is exchanged between directly interacting fluids. Unlike steady ejectors, the mechanism responsible for the energy transfer is reversible in nature and thus higher efficiencies are perceivable. A potential application for PEE is for enhancement in output power per weight as in turbochargers. The unsteady ejector when used as a turbocharger the device is expected to perform under wide range of ambient temperatures. Therefore, it is important to investigate the effects of the temperature of the induced ambient air on the energy transfer. The radial-flow ejector, which usually leads to higher-pressure ratios with fewer stages, was selected for the investigation. The flow field is investigated at two Mach numbers 2.5 and 3.0 utilizing rectangular short-length supersonic nozzles for accelerating the primary fluid. Fundamental to the enhancement of these devices performance relies on the management of the flow field in such a way to minimize entropy production. The numerical analyses were conducted utilizing a package of computational fluid dynamics.

  9. Recent developments in electrochemical flow detections--a review part II. Liquid chromatography.

    PubMed

    Trojanowicz, Marek

    2011-02-28

    This article is a review of the progress in application of electrochemical detections in liquid chromatography in recent 15-20 years. Based on 238 references, mostly to original research papers, it presents applications of amperometric and voltammetric detections, as well as coulometric, conductimetric and potentiometric ones. In case of those which have reached already the stage of routinely employed detections with commercially available instrumentation (amperometry, coulometry, conductometry) especially novel and original applications are presented. In case of voltammetric and potentiometric detections a ways of their improvements are showed, directed towards obtaining competitive results with other detection methods. PMID:21296201

  10. Travel time distributions under convergent radial flow in heterogeneous formations: Insight from the analytical solution of a stratified model

    NASA Astrophysics Data System (ADS)

    Pedretti, Daniele; Fiori, Aldo

    2013-10-01

    We analyze conservative solute transport under convergent flow to a well in perfectly stratified porous media, in which the hydraulic conductivity is treated as a random spatial function along the vertical direction (K(z)). The stratified model provides a rare exception of an exact analytical solution of travel time distributions in the proximity of pumping wells, and it is used here to obtain insights about ergodic and nonergodic transport conditions under nonuniform flow conditions. In addition, it provides a benchmark for numerical models aiming to correctly reproduce convergent flow transport in heterogeneous media, such as indicating the minimum number of layers required to obtain ergodic travel time distributions using only one model realization. The model provides important insights about the shape of the depth-integrated concentrations over time measured at the well (breakthrough curves, BTCs), which are usually applied to obtain transport parameters of the subsurface. It can be applied to any degree of system's heterogeneity and using either resident or flux-weighted injection modes. It can be built using different probabilistic distributions of K. In our analysis, we consider a log-normal K distribution, and the results indicate that, especially for highly heterogeneous systems, described by the log-K variance (σY2), the minimum number of layers required for from one model simulation to reproduce ergodic travel time distributions can be prohibitively high, e.g., above 106 for σY2=8 considering flux-weighted injections. This issue poses serious concerns for numerical applications aiming to simulate transport in the proximity of pumping wells. In addition, this simple solution confirms that stratification can lead BTCs to display strong preferential flow and persistent, power-law-like late-time tailing. Since the latter are common phenomenological macroscale evidences of other microscale hydrodynamic processes than pure advection (e.g., mass

  11. Conformational transitions of macromolecules in an eluent flow and their manifestation in the chromatography of polymers

    NASA Astrophysics Data System (ADS)

    Kurganov, A. A.; Kanateva, A. Yu; Orekhov, V. A.

    2014-07-01

    The behaviour of macromolecules in a free eluent flow, in a confined space, and in a flow passing through a pore system is considered. It is shown that the behaviour of macromolecules can be described by different theories such as the De Gennes theory and the theory of A DiMarzio and C M Guttman. Specific features of chromatographic fractionation and separation processes with the use of membranes formed from ultrahigh-molecular-mass polymers, which are widely used as constructional materials, are discussed. To account for these features, theoretical models considering conformational transitions of macromolecules in the eluent flow and taking into account possible degradation of macromolecules under the influence of the flow are applied. The current state of theoretical and experimental studies of the behaviour of macromolecules in a fluid flow is surveyed. The bibliography includes 152 references.

  12. Lateral flow microarrays: a novel platform for rapid nucleic acid detection based on miniaturized lateral flow chromatography

    PubMed Central

    Carter, Darren J.; Cary, R. Bruce

    2007-01-01

    Widely used nucleic acid assays are poorly suited for field deployment where access to laboratory instrumentation is limited or unavailable. The need for field deployable nucleic acid detection demands inexpensive, facile systems without sacrificing information capacity or sensitivity. Here we describe a novel microarray platform capable of rapid, sensitive nucleic acid detection without specialized instrumentation. The approach is based on a miniaturized lateral flow device that makes use of hybridization-mediated target capture. The miniaturization of lateral flow nucleic acid detection provides multiple advantages over traditional lateral flow devices. Ten-microliter sample volumes reduce reagent consumption and yield analyte detection times, excluding sample preparation and amplification, of <120 s while providing sub-femtomole sensitivity. Moreover, the use of microarray technology increases the potential information capacity of lateral flow. Coupled with a hybridization-based detection scheme, the lateral flow microarray (LFM) enables sequence-specific detection, opening the door to highly multiplexed implementations for broad-range assays well suited for point-of-care and other field applications. The LFM system is demonstrated using an isothermal amplification strategy for detection of Bacillus anthracis, the etiologic agent of anthrax. RNA from as few as two B. anthracis cells was detected without thermocycling hardware or fluorescence detection systems. PMID:17478499

  13. Online spectrophotometric determination of Fe(II) and Fe(III) by flow injection combined with low pressure ion chromatography

    NASA Astrophysics Data System (ADS)

    Chen, Shujuan; Li, Nan; Zhang, Xinshen; Yang, Dongjing; Jiang, Heimei

    2015-03-01

    A simple and new low pressure ion chromatography combined with flow injection spectrophotometric procedure for determining Fe(II) and Fe(III) was established. It is based on the selective adsorption of low pressure ion chromatography column to Fe(II) and Fe(III), the online reduction reaction of Fe(III) and the reaction of Fe(II) in sodium acetate with phenanthroline, resulting in an intense orange complex with a suitable absorption at 515 nm. Various chemical (such as the concentration of colour reagent, eluant and reductive agent) and instrumental parameters (reaction coil length, reductive coil length and wavelength) were studied and were optimized. Under the optimum conditions calibration graph of Fe(II)/Fe(III) was linear in the Fe(II)/Fe(III) range of 0.040-1.0 mg/L. The detection limit of Fe(III) and Fe(II) was respectively 3.09 and 1.55 μg/L, the relative standard deviation (n = 10) of Fe(II) and Fe(III) 1.89% and 1.90% for 0.5 mg/L of Fe(II) and Fe(III) respectively. About 2.5 samples in 1 h can be analyzed. The interfering effects of various chemical species were studied. The method was successfully applied in the determination of water samples.

  14. Online spectrophotometric determination of Fe(II) and Fe(III) by flow injection combined with low pressure ion chromatography.

    PubMed

    Chen, Shujuan; Li, Nan; Zhang, Xinshen; Yang, Dongjing; Jiang, Heimei

    2015-03-01

    A simple and new low pressure ion chromatography combined with flow injection spectrophotometric procedure for determining Fe(II) and Fe(III) was established. It is based on the selective adsorption of low pressure ion chromatography column to Fe(II) and Fe(III), the online reduction reaction of Fe(III) and the reaction of Fe(II) in sodium acetate with phenanthroline, resulting in an intense orange complex with a suitable absorption at 515nm. Various chemical (such as the concentration of colour reagent, eluant and reductive agent) and instrumental parameters (reaction coil length, reductive coil length and wavelength) were studied and were optimized. Under the optimum conditions calibration graph of Fe(II)/Fe(III) was linear in the Fe(II)/Fe(III) range of 0.040-1.0mg/L. The detection limit of Fe(III) and Fe(II) was respectively 3.09 and 1.55μg/L, the relative standard deviation (n=10) of Fe(II) and Fe(III) 1.89% and 1.90% for 0.5mg/L of Fe(II) and Fe(III) respectively. About 2.5 samples in 1h can be analyzed. The interfering effects of various chemical species were studied. The method was successfully applied in the determination of water samples. PMID:25523043

  15. Rapid identification of airborne biological particles by flow cytometry, gas chromatography, and genetic probes. Final report, January 1995-January 1997

    SciTech Connect

    Wick, C.H.; Carlon, H.R.; Edmonds, R.L.; Robert, L.; Blew, J.

    1997-09-01

    Detection of airborne biological particulates is a primary mission of the U.S. Army Edgewood Research, Development and Engineering Center biological defense program. If biological particles could be characterized according to their unique physical and biochemical profiles, detection and perhaps even identification of the particles might be possible. This study focused upon microbial particles, more specifically upon fungal spores, yeast cells, and bacterial cells. Physical characteristics of the particles, it was proposed, could be detected by flow cytometry, while their biochemical profiles could be determined by gas chromatography, and their genetic identity could be obtained by either a suitable genetic probe or by matching its genetic fingerprint. Genetic techniques were not attempted in the work reported here, but the approach was investigated further. Trial results were encouraging.

  16. Preparation of pure, high titer, pseudoinfectious Flavivirus particles by hollow fiber tangential flow filtration and anion exchange chromatography.

    PubMed

    Mundle, Sophia T; Giel-Moloney, Maryann; Kleanthous, Harry; Pugachev, Konstantin V; Anderson, Stephen F

    2015-08-20

    Purification of enveloped viruses such as live flavivirus vaccine candidates poses a challenge as one must retain viral infectivity to preserve immunogenicity. Here we describe a laboratory-scale purification procedure for two replication defective (single-cycle) flavivirus variants for use in a pre-clinical setting. The two step purification scheme based on hollow fiber tangential flow filtration (TFF) followed by anion exchange chromatography using convective interaction media (CIM(®)) monoliths results in a ∼60% recovery of infectious virus titer and can be used to prepare nearly homogenous, highly purified vaccine viruses with titers as high as 1×10(9) focus forming units per mL. Flavivirus virions prepared by this method are 2 and 3 orders of magnitude more pure with respect to dsDNA and BHK host cell proteins, respectively, as compared to the raw feed stream. PMID:25498209

  17. Radial Erosion

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The ejecta surrounding the crater (off image to the left) in this image has undergone significant erosion by the wind. The wind has stripped the surface features from the ejecta and has started to winnow away the ejecta blanket. Near the margin of the ejecta the wind is eroding along a radial pattern -- taking advantage of radial emplacement. Note the steep margin of the ejecta blanket. Most, if not all, of the fine ejecta material has been removed and the wind in now working on the more massive continuous ejecta blanket.

    Image information: VIS instrument. Latitude 12.5, Longitude 197.4 East (162.6 West). 37 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  18. Radial and circumferential flow surveys at the inlet and exit of the Space Shuttle Main Engine High Pressure Fuel Turbine Model

    NASA Astrophysics Data System (ADS)

    Hudson, S. T.; Bordelon, W. J., Jr.; Smith, A. W.; Ramachandran, N.

    1995-01-01

    The main objective of this test was to obtain detailed radial and circumferential flow surveys at the inlet and exit of the SSME High Pressure Fuel Turbine model using three-hole cobra probes, hot-film probes, and a laser velocimeter. The test was designed to meet several objectives. First, the techniques for making laser velocimeter, hot-film probe, and cobra probe measurements in turbine flows were developed and demonstrated. The ability to use the cobra probes to obtain static pressure and, therefore, velocity had to be verified; insertion techniques had to be established for the fragile hot-film probes; and a seeding method had to be established for the laser velocimetry. Once the measurement techniques were established, turbine inlet and exit velocity profiles, temperature profiles, pressure profiles, turbulence intensities, and boundary layer thicknesses were measured at the turbine design point. The blockage effect due to the model inlet and exit total pressure and total temperature rakes on the turbine performance was also studied. A small range of off-design points were run to obtain the profiles and to verify the rake blockage effects off-design. Finally, a range of different Reynolds numbers were run to study the effect of Reynolds number on the various measurements.

  19. Numerical investigation of a coupled moving boundary model of radial flow in low-permeable stress-sensitive reservoir with threshold pressure gradient

    NASA Astrophysics Data System (ADS)

    Wen-Chao, Liu; Yue-Wu, Liu; Cong-Cong, Niu; Guo-Feng, Han; Yi-Zhao, Wan

    2016-02-01

    The threshold pressure gradient and formation stress-sensitive effect as the two prominent physical phenomena in the development of a low-permeable reservoir are both considered here for building a new coupled moving boundary model of radial flow in porous medium. Moreover, the wellbore storage and skin effect are both incorporated into the inner boundary conditions in the model. It is known that the new coupled moving boundary model has strong nonlinearity. A coordinate transformation based fully implicit finite difference method is adopted to obtain its numerical solutions. The involved coordinate transformation can equivalently transform the dynamic flow region for the moving boundary model into a fixed region as a unit circle, which is very convenient for the model computation by the finite difference method on fixed spatial grids. By comparing the numerical solution obtained from other different numerical method in the existing literature, its validity can be verified. Eventually, the effects of permeability modulus, threshold pressure gradient, wellbore storage coefficient, and skin factor on the transient wellbore pressure, the derivative, and the formation pressure distribution are analyzed respectively. Project supported by the National Natural Science Foundation of China (Grant No. 51404232), the China Postdoctoral Science Foundation (Grant No. 2014M561074), and the National Science and Technology Major Project, China (Grant No. 2011ZX05038003).

  20. Oscillatory limited compressible fluid flow induced by the radial motion of a thick-walled piezoelectric tube

    NASA Astrophysics Data System (ADS)

    Shin, Dong-Youn; Grassia, Paul; Derby, Brian

    2003-09-01

    A simple oscillatory, slightly compressible, fluid flow model in a thick-walled piezoelectric tube used in a drop-on-demand inkjet print head is developed from the point of view of fluid-structure interaction to take account of pressure wave propagation and pressure loading opposing wall motion. A frequency sweep is performed computationally using the model revealing the first acoustic fluid-structure resonance frequency and the influence of fluid viscosity. The validity of the model, with given information on the speed of sound in a fluid, is evaluated by comparing the theoretically predicted resonance frequency to the experimentally measured resonance frequency. In addition, the intrinsic speed of sound can be easily computed using the measured acoustic resonance frequency and this computed speed of sound agrees closely with speeds of sound reported in the literature.

  1. Effects of climatic conditions on radial growth and sap-flow along an elevation gradient in an inner-alpine dry valley

    NASA Astrophysics Data System (ADS)

    Obojes, Nikolaus; Newesely, Christian; Bertoldi, Giacomo; Tassser, Erich; Oberhuber, Walter; Mayr, Stefan; Tappeiner, Ulrike

    2016-04-01

    Water availability in mountain forests might change in the future due to rising temperatures and changing precipitation patterns, affecting tree water relations and growth conditions. Changing temperature and precipitation along an elevation gradient in an inner-alpine dry valley in South Tyrol-Italy were used to investigate possible effects of climate change on the transpiration and growth of European Larch (Larix decidua). Stem circumference variation of European Larch was measured for 4 years (2012-2015) with automatic band dendrometers and sap flow for 2 years (2013-2014) with trunk heat balance sensors at 3 sites at elevations of 1115 m, 1715 m, and 1990 m above sea level at a SE-exposed slope. During the first two, rather dry, years, transpiration and stem circumference were reduced during dry periods of one to three weeks at the two lower but not at the highest site. As a consequence, overall yearly radial growth was largest at the highest site in those two years. In 2014, with very high precipitation and colder summer temperatures no correlation of elevation, transpiration, and radial growth was observed. In 2015, with a dry and hot summer, initially high growth rates were strongly reduced after the end of May at the two lower sites. Overall the radial growth of Larix decidua seems to be limited by water scarcity up to an elevation of more than 1700 m a.s.l. in our study area except for unusually wet years. Our 4-year measurements were confirmed by dendro-climatic analysis of stem cores taken at five sites (the three original ones plus two additional sites at 1070 and at the forest line at 2250m) covering the last 50 to 150 years. Year ring widths were lower and highly correlated to precipitation at the lowest sites, and overall highest at the 1990 m site. Our results show that the growth of Larix decidua, which is often considered as more drought resistant than e.g. Picea abies, is limited by water availability at dry conditions in the Alps which might

  2. MERIDL- VELOCITIES AND STREAMLINES ON THE HUB-SHROUD MIDCHANNEL STREAM SURFACE OF AN AXIAL, RADIAL, OR MIXED FLOW TURBOMACHINE OR ANNULAR DUCT

    NASA Technical Reports Server (NTRS)

    Katsanis, T.

    1994-01-01

    general the blade row may be fixed or rotating and the blades may be twisted and leaned. The flow may be axial, radial, or mixed. The upstream and downstream flow conditions can vary from hub to shroud with provisions made for an approximate correction for loss of stagnation pressure. Also, viscous forces are neglected along solution mesh lines running from hub to tip. The capabilities of this program include handling of nonaxial flows without restriction, annular ducts without blades, and specified streamwise loss distributions. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 360 computer with a central memory requirement of approximately 700K of 8 bit bytes. This core requirement can be reduced depending on the size of the problem and the desired solution accuracy. This program was developed in 1977.

  3. Enantioselective stopped-flow multidimensional gas chromatography. Determination of the inversion barrier of 1-chloro-2,2-dimethylaziridine.

    PubMed

    Reich, S; Trapp, O; Schurig, V

    2000-09-15

    Enantioselective stopped-flow multidimensional gas chromatography (stopped-flow MDGC) is a fast and simple technique to determine enantiomerization (inversion) barriers in the gas phase in a range of delta G#gas(T)=70-200 kJ mol(-1). After complete gas-chromatographic separation of the enantiomers in the first column, gas phase enantiomerization of the heart-cut fraction of one single enantiomer is performed in the second (reactor) column at increased temperature and afterwards this fraction is separated into the enantiomers in the third column. From the observed de novo enantiomeric peak areas a(j), the enantiomerization time t and the enantiomerization temperature T, the enantiomerization (inversion) barrier delta G#gas(T) is determined and from temperature-dependent experiments, the activation enthalpy delta H#gas and the activation entropy delta S#gas are obtained. Enantiomerization studies on chiral 1-chloro-2,2-dimethylaziridine by stopped-flow MDGC yielded activation parameters of nitrogen inversion in the gas phase, i.e., delta G#gas(353 K)=110.5+/-0.5 kJ mol(-1), delta H#gas=71.0+/-3.8 kJ mol(-1) and delta S#gas=-109+/-11 J mol(-1) K(-1). By the complementary method of dynamic gas chromatography (GC), the apparent enantiomerization (inversion) barrier of 1-chloro-2,2-dimethylaziridine in the gas-liquid biphase system was found delta G#app(353 K)=108 kJ mol(-1). The values obtained by stopped-flow MDGC in the gas phase were used to calculate the activation parameters of nitrogen inversion of 1-chloro-2,2-dimethylaziridine in the liquid phase in the presence of the chiral selector Chirasil-nickel(II), i.e.. deltaG#liq(353 K)=106.0+/-0.4 kJ mol(-1), delta H#liq=68.3+/-1.4 kJ mol(-1) and deltaS#liq=-106+/-3.0 J mol(-1) K(-1). PMID:11045506

  4. Spectra and radial flow in relativistic heavy ion collisions with Tsallis statistics in a blast-wave description

    SciTech Connect

    Tang Zebo; Xu Yichun; Ruan Lijuan; Buren, Gene van; Xu Zhangbu; Wang Fuqiang

    2009-05-15

    We have implemented the Tsallis statistics in a Blast-Wave model (TBW) and applied it to midrapidity transverse-momentum spectra of identified particles measured at BNL Relativistic Heavy Ion Collider (RHIC). This new TBW function fits the RHIC data very well for p{sub T}<3 GeV/c. We observed that the collective flow velocity starts from zero in p+p and peripheral Au+Au collisions and grows to 0.470{+-}0.009c in central Au+Au collisions. The resulting (q-1) parameter, which characterizes the degree of nonequilibrium in a system, indicates an evolution from a highly nonequilibrated system in p+p collisions toward an almost thermalized system in central Au+Au collisions. The temperature and collective velocity are well described by a quadratic dependence on (q-1). Two sets of parameters in our TBW are required to describe the meson and baryon groups separately in p+p collisions while one set appears to fit all spectra in central Au+Au collisions.

  5. Development and validation of a radial inflow turbine model for simulation of the SNL S-CO2 split-flow loop.

    SciTech Connect

    Vilim, R. B.

    2012-07-31

    A one-dimensional model for a radial inflow turbine has been developed for super-critical carbon dioxide (S-CO{sub 2}) Brayton cycle applications. The model accounts for the main phenomena present in the volute, nozzle, and impeller of a single-stage turbine. These phenomena include internal losses due to friction, blade loading, and angle of incidence and parasitic losses due to windage and blade-housing leakage. The model has been added as a component to the G-PASS plant systems code. The model was developed to support the analysis of S-CO{sub 2} cycles in conjunction with small-scale loop experiments. Such loops operate at less than a MWt thermal input. Their size permits components to be reconfigured in new arrangements relatively easily and economically. However, the small thermal input combined with the properties of carbon dioxide lead to turbomachines with impeller diameters of only one to two inches. At these sizes the dominant phenomena differ from those in larger more typical machines. There is almost no treatment in the literature of turbomachines at these sizes. The present work therefore is aimed at developing turbomachine models that support the task of S-CO{sub 2} cycle analysis using small-scale tests. Model predictions were compared against data from an experiment performed for Sandia National Laboratories in the split-flow Brayton cycle loop currently located at Barber-Nichols Inc. The split-flow loop incorporates two turbo-alternator-compressor (TAC) units each incorporating a radial inflow turbine and a radial flow compressor on a common shaft. The predicted thermodynamic conditions at the outlet of the turbine on the main compressor shaft were compared with measured values at different shaft speeds. Two modifications to the original model were needed to better match the experiment data. First, a representation of the heat loss from the volute downstream of the sensed inlet temperature was added. Second, an empirical multiplicative factor was

  6. Radial Inflow Turboexpander Redesign

    SciTech Connect

    William G. Price

    2001-09-24

    Steamboat Envirosystems, LLC (SELC) was awarded a grant in accordance with the DOE Enhanced Geothermal Systems Project Development. Atlas-Copco Rotoflow (ACR), a radial expansion turbine manufacturer, was responsible for the manufacturing of the turbine and the creation of the new computer program. SB Geo, Inc. (SBG), the facility operator, monitored and assisted ACR's activities as well as provided installation and startup assistance. The primary scope of the project is the redesign of an axial flow turbine to a radial inflow turboexpander to provide increased efficiency and reliability at an existing facility. In addition to the increased efficiency and reliability, the redesign includes an improved reduction gear design, and improved shaft seal design, and upgraded control system and a greater flexibility of application

  7. Revised FORTRAN program for calculating velocities and streamlines on the hub-shroud midchannel stream surface of an axial-, radial-, or mixed-flow turbomachine or annular duct. 2: Programmer's manual

    NASA Technical Reports Server (NTRS)

    Katsanis, T.; Mcnally, W. D.

    1977-01-01

    A FORTRAN IV computer program has been developed that obtains a detailed subsonic or shock free transonic flow solution on the hub-shroud midchannel stream surface of a turbomachine. The blade row may be fixed or rotating, and the blades may be twisted and leaned. Flow may be axial, mixed, or radial. Upstream and downstream flow variables may vary from hub to shroud, and provisions are made to correct for loss of stagnation pressure. The results include velocities, streamlines, and flow angles on the stream surface and approximate blade surface velocities.

  8. Radiolabeling and Quantification of Cellular Levels of Phosphoinositides by High Performance Liquid Chromatography-coupled Flow Scintillation.

    PubMed

    Ho, Cheuk Y; Choy, Christopher H; Botelho, Roberto J

    2016-01-01

    Phosphoinositides (PtdInsPs) are essential signaling lipids responsible for recruiting specific effectors and conferring organelles with molecular identity and function. Each of the seven PtdInsPs varies in their distribution and abundance, which are tightly regulated by specific kinases and phosphatases. The abundance of PtdInsPs can change abruptly in response to various signaling events or disturbance of the regulatory machinery. To understand how these events lead to changes in the amount of PtdInsPs and their resulting impact, it is important to quantify PtdInsP levels before and after a signaling event or between control and abnormal conditions. However, due to their low abundance and similarity, quantifying the relative amounts of each PtdInsP can be challenging. This article describes a method for quantifying PtdInsP levels by metabolically labeling cells with (3)H-myo-inositol, which is incorporated into PtdInsPs. Phospholipids are then precipitated and deacylated. The resulting soluble (3)H-glycero-inositides are further extracted, separated by high-performance liquid chromatography (HPLC), and detected by flow scintillation. The labeling and processing of yeast samples is described in detail, as well as the instrumental setup for the HPLC and flow scintillator. Despite losing structural information regarding acyl chain content, this method is sensitive and can be optimized to concurrently quantify all seven PtdInsPs in cells. PMID:26780479

  9. Top-down and bottom-up lipidomic analysis of rabbit lipoproteins under different metabolic conditions using flow field-flow fractionation, nanoflow liquid chromatography and mass spectrometry.

    PubMed

    Byeon, Seul Kee; Kim, Jin Yong; Lee, Ju Yong; Chung, Bong Chul; Seo, Hong Seog; Moon, Myeong Hee

    2015-07-31

    This study demonstrated the performances of top-down and bottom-up approaches in lipidomic analysis of lipoproteins from rabbits raised under different metabolic conditions: healthy controls, carrageenan-induced inflammation, dehydration, high cholesterol (HC) diet, and highest cholesterol diet with inflammation (HCI). In the bottom-up approach, the high density lipoproteins (HDL) and the low density lipoproteins (LDL) were size-sorted and collected on a semi-preparative scale using a multiplexed hollow fiber flow field-flow fractionation (MxHF5), followed by nanoflow liquid chromatography-ESI-MS/MS (nLC-ESI-MS/MS) analysis of the lipids extracted from each lipoprotein fraction. In the top-down method, size-fractionated lipoproteins were directly infused to MS for quantitative analysis of targeted lipids using chip-type asymmetrical flow field-flow fractionation-electrospray ionization-tandem mass spectrometry (cAF4-ESI-MS/MS) in selected reaction monitoring (SRM) mode. The comprehensive bottom-up analysis yielded 122 and 104 lipids from HDL and LDL, respectively. Rabbits within the HC and HCI groups had lipid patterns that contrasted most substantially from those of controls, suggesting that HC diet significantly alters the lipid composition of lipoproteins. Among the identified lipids, 20 lipid species that exhibited large differences (>10-fold) were selected as targets for the top-down quantitative analysis in order to compare the results with those from the bottom-up method. Statistical comparison of the results from the two methods revealed that the results were not significantly different for most of the selected species, except for those species with only small differences in concentration between groups. The current study demonstrated that top-down lipid analysis using cAF4-ESI-MS/MS is a powerful high-speed analytical platform for targeted lipidomic analysis that does not require the extraction of lipids from blood samples. PMID:26087967

  10. Hollow fiber flow field-flow fractionation and size-exclusion chromatography with MALS detection: A complementary approach in biopharmaceutical industry.

    PubMed

    Marassi, V; Roda, B; Zattoni, A; Tanase, M; Reschiglian, P

    2014-10-30

    Monoclonal antibodies (mAbs) are promising reagents both for the manufacture of drug substances and for their employment as a drug themselves, but to be approved for utilization, according to FDA recommendations and WHO guidelines, they have to undergo verifications regarding their purity, stability and percentage of aggregates. Moreover, stability tests of lots have to be performed in order to verify molecular size distribution over time and lot-to-lot consistency. Recent works in literature have highlighted the need for suitable, sensitive and reliable complementary analytical techniques for the characterization of mAbs and quantification of aggregates. Size-exclusion chromatography (SEC) is the reference technique in the biopharmaceutical industry for its robustness, high performance and simple use; however it presents some limitations especially toward the separation and detection of aggregates with high molecular weight. On the other hand, flow field-flow fractionation (F4) in its miniaturized version (hollow fiber flow field-flow fractionation, HF5) shows comparable performances with interesting additional advantages: a broad size range, gentle separation mechanism with low dilution factor and higher sensitivity. To propose HF5 as a complementary technique for evaluating aggregates' content in mAbs samples, a comparative study of both SEC and HF5 performances has been made. In this work, SEC and HF5 were coupled with UV and multi-angle light scattering detection and employed first in separating standard samples of proteins mixture used as a sample model. Then, a screening of mobile phases and an evaluation of separation performances was performed on a therapeutic mAbs formulation, demonstrating the complementarities between SEC and HF5 and their possible use as a separative platform approach for the characterization and quality control of protein drugs. PMID:25468501

  11. Capillary liquid chromatography fraction collection and postcolumn reaction using segmented flow microfluidics.

    PubMed

    Nie, Jing; Kennedy, Robert T

    2013-11-01

    A challenge for capillary LC (cLC) is fraction collection and the manipulation of fractions from microscale columns. An emerging approach is the use of segmented flow or droplet technology to perform such tasks. In this work, a fraction collection and postcolumn reaction system based on segmented flow was developed for the gradient cLC of proteins. In the system, column effluent and immiscible oil are pumped into separate arms of a tee resulting in regular fractions of effluent segmented by oil. Fractions were generated at 1 Hz corresponding to 5 nL volumes. The fraction collection rate was high enough to generate over 30 fractions per peak and preserve chromatographic resolution achieved for a five-protein test mixture. The resulting fractions could be stored and subsequently derivatized for fluorescence detection by pumping them into a second tee where naphthalene dicarboxyaldehyde, a fluorogenic reagent, was pumped into a second arm and added to each fraction. Proteins were derivatized within the droplets enabling postcolumn fluorescence detection of the proteins. The experiments demonstrate that fraction collection from cLC by segmented flow can be extended to proteins. Further, they illustrate a potential workflow for protein analysis based on postcolumn derivatization for fluorescence detection. PMID:24039151

  12. Measurement of bromate in bread by liquid chromatography with post-column flow reactor detection.

    PubMed

    Himata, K; Noda, M; Ando, S; Yamada, Y

    2000-01-01

    This method is suitable for the determination of bromate residues in a variety of baked goods. The peer-verified method trial was performed on white bread, multigrain bread, and coffee cake spiked with known levels of potassium bromate. The analytical portion is extracted with deionized water to remove bromate from the bulk of the baked product. The aqueous extract is carried through a series of steps to remove co-extractives that would interfere with the liquid chromatography (LC) in the determinative step or hasten the deterioration of the LC column. The extract is filtered before passing it through a reversed-phase solid-phase extraction (SPE) column and a cation-exchange column in the silver form to remove lipids and chloride, respectively. Ultrafiltration is then used to remove proteins with molecular weights of >30,000 daltons. Finally, a cation-exchange column in the sodium form is used to remove silver ions from the extract. The determinative step uses LC with a reversed-phase column and an ion-pairing agent in the mobile phase. Detection is based on the post-column reaction of bromate with o-dianisidine to form an oxidation product that is quantitated spectrophotometrically at 450 nm. Overall agreement between the submitting and peer laboratories was quite good. For bromate levels of 10-52 ppb, overall mean recoveries were 76.9 and 78.8% for the submitting and peer laboratories, respectively. The standard deviations were higher for the results of the peer laboratory, probably because of the generally higher level of baseline noise present in the chromatograms. The results demonstrate that the method provides adequate accuracy with low-fat as well as high-fat foods. Bromate at levels as low as 5 ppb (ng/g) can be detected with the method. PMID:10772172

  13. Kinetic behaviour in supercritical fluid chromatography with modified mobile phase for 5 μm particle size and varied flow rates.

    PubMed

    Lesellier, E; Fougere, L; Poe, Donald P

    2011-04-15

    After much development of stationary phase chemistry, in recent years the focus of many studies in HPLC has shifted to increase the efficiency and analysis speed. Ultra high pressure liquid chromatography (UHPLC) using sub-2 μm particles, and high temperature liquid chromatography (HTLC), using temperatures above 100°C have received much attention. These new approaches allow the use of flow rates higher than those classically used in HPLC, reducing the analysis duration. Due to the low viscosity of supercritical fluids, high velocities, i.e. high flow rates, can be achieved with classical pumping systems typically used in supercritical fluid chromatography (SFC). The effects of the flow rate increase with CO(2)/methanol mobile phase was studied on the inlet pressure, t(0), the retention factor of the compounds, and on the efficiency. Simple comparisons of efficiencies obtained at varied temperature between SFC and HPLC, with a packed column containing 5 μm particles, show the greater kinetic performances achieved with the CO(2)/methanol fluid, and underline specific behaviours of SFC, occurring for high flow rates and sub-ambient temperature. Some values (N/t(0)) are also compared to UHPLC data, showing that good performance can be achieved in SFC without applying drastic analytical conditions. Finally, simple kinetic plots (t(0) vs N) at constant column length are used to select combinations of temperature and flow rate necessary to achieve a required theoretical plate number. PMID:21232748

  14. Ultra-low Flow Liquid Chromatography Assay with Ultraviolet (UV) Detection for Piperine Quantitation in Human Plasma

    PubMed Central

    Kakarala, Madhuri; Dubey, Shiv Kumar; Tarnowski, Malloree; Cheng, Connie; Liyanage, Samadhi; Strawder, Terrence; Tazi, Karim; Sen, Ananda; Djuric, Zora; Brenner, Dean E.

    2015-01-01

    A robust and sensitive ultra-low flow liquid chromatography (UFLC) method that can reproducibly, at reasonable cost, detect low concentrations of piperine from human plasma is necessary. Piperine in plasma was separated and quantified by a gradient method using ultraviolet detection at a maximal absorbance wavelength of 340 nm. An aliquot was injected onto a reversed-phase column Waters SymmetryShield, 2.1 × 100 mm, 3.5 μm, C18 column, attached to a Waters absorbosphere, 4.6 × 30 mm, C18 guard column and eluted with a mobile phase containing a mixture of acetonitrile/water/ acetic acid (25:74.9:0.1, v/v/v) on line A and acetonitrile/acetic acid (99.9:0.1, v/v) on line B. The flow rate was 0.3 mL/min. The gradient method consisted of an opening condition of 20% pump B, with a linear increase to 37% pump B over 8 min, then a linear increase to 100% pump B at 11 min, 2 min at 100% pump B, and then a return to the opening condition (20% pump B) via a linear gradient over 2 min, followed by 5 min re-equilibration at opening conditions. The total run time was 20 min for each sample. All samples were processed protected from ambient light to avoid isomerization of piperine. The plasma assay was linear with R = 0.9995, with a lower limit of detection [signal-to-noise (S/N) > 5:1] of 100 pg of piperine loaded into the analytical system with acceptable accuracy and precision. Extraction recoveries of piperine from human plasma were 88% for quality control high (QCH), 93% for quality control medium (QCM), and 90% for quality control low (QCL), and the matrix effect was <12%. Piperine was quantifiable from a 50 mg oral dose given to human volunteers. A UFLC method for the rapid assay of human plasma with sensitivity to detect as low as 5 ng/mL piperine was developed. The method sensitivity equals that of liquid chromatography/tandem mass spectrometry (LC/MSMS) methods with much less cost. PMID:20465211

  15. High-pressure size exclusion chromatography analysis of dissolved organic matter isolated by tangential-flow ultra filtration

    USGS Publications Warehouse

    Everett, C.R.; Chin, Y.-P.; Aiken, G.R.

    1999-01-01

    A 1,000-Dalton tangential-flow ultrafiltration (TFUF) membrane was used to isolate dissolved organic matter (DOM) from several freshwater environments. The TFUF unit used in this study was able to completely retain a polystyrene sulfonate 1,800-Dalton standard. Unaltered and TFUF-fractionated DOM molecular weights were assayed by high-pressure size exclusion chromatography (HPSEC). The weight-averaged molecular weights of the retentates were larger than those of the raw water samples, whereas the filtrates were all significantly smaller and approximately the same size or smaller than the manufacturer-specified pore size of the membrane. Moreover, at 280 nm the molar absorptivity of the DOM retained by the ultrafilter is significantly larger than the material in the filtrate. This observation suggests that most of the chromophoric components are associated with the higher molecular weight fraction of the DOM pool. Multivalent metals in the aqueous matrix also affected the molecular weights of the DOM molecules. Typically, proton-exchanged DOM retentates were smaller than untreated samples. This TFUF system appears to be an effective means of isolating aquatic DOM by size, but the ultimate size of the retentates may be affected by the presence of metals and by configurational properties unique to the DOM phase.

  16. Flowing atmospheric pressure afterglow combined with laser ablation for direct analysis of compounds separated by thin-layer chromatography.

    PubMed

    Cegłowski, Michał; Smoluch, Marek; Reszke, Edward; Silberring, Jerzy; Schroeder, Grzegorz

    2016-01-01

    A thin-layer chromatography-mass spectrometry (TLC-MS) setup for characterization of low molecular weight compounds separated on standard TLC plates has been constructed. This new approach successfully combines TLC separation, laser ablation, and ionization using flowing atmospheric pressure afterglow (FAPA) source. For the laser ablation, a low-priced 445-nm continuous-wave diode laser pointer, with a power of 1 W, was used. The combination of the simple, low-budget laser pointer and the FAPA ion source has made this experimental arrangement broadly available, also for small laboratories. The approach was successfully applied for the characterization of low molecular weight compounds separated on TLC plates, such as a mixture of pyrazole derivatives, alkaloids (nicotine and sparteine), and an extract from a drug tablet consisting of paracetamol, propyphenazone, and caffeine. The laser pointer used was capable of ablating organic compounds without the need of application of any additional substances (matrices, staining, etc.) on the TLC spots. The detection limit of the proposed method was estimated to be 35 ng/cm(2) of a pyrazole derivative. PMID:26563110

  17. Thermal Solid Sample Introduction-Fast Gas Chromatography-Low Flow Ion Mobility Spectrometry as a field screening detection system.

    PubMed

    Hajialigol, Saeed; Ghorashi, Seyed Alireza; Alinoori, Amir Hossein; Torabpour, Amir; Azimi, Mehdi

    2012-12-14

    The potential of Thermal Solid Sample Introduction (TSSI)-Fast Gas Chromatography (GC)-Low Flow Ion Mobility Spectrometry (LF-IMS) having been designed and constructed in Engineering Research Center of Esfahan, detector group was investigated for chemical detection capabilities. Customizing the configuration of fast GC-IMS as a high technology, provides unique solutions for rapid detection of a broad range of chemical mixtures in many operational environments. TSSI configuration provides fast and easily applied method for direct detection with no additional sample preparation or extraction. The time required for total analysis, less than 265 s, was determined by the wide range of solid matrixes, including nitrate esters, nitroaromatics, and a nitramine. The fast extraction together with the short separation time limits degradation of the thermally labile compounds and decreases the peak widths, which results in larger peak intensities and a simultaneous improvement in detection limits. For signal-to-noise ratio equals to 5, the detection limits for instrument for TNT, DNT and RDX were attained 15, 10 and 50 ng/μl respectively. The combination of short analysis time and low detection limits make this instrument a potential candidate for field screening techniques. PMID:23141709

  18. Quantification of Docetaxel in Serum Using Turbulent Flow Liquid Chromatography Electrospray Tandem Mass Spectrometry (TFC-HPLC-ESI-MS/MS).

    PubMed

    Crutchfield, Christopher A; Marzinke, Mark A; Clarke, William A

    2016-01-01

    Docetaxel is a second-generation taxane and is used clinically as an anti-neoplastic agent in cancer chemotherapy via an anti-mitotic mechanism. Its efficacy is limited to a narrow therapeutic window. Inappropriately high concentrations may cause erythema, fluid retention, nausea, diarrhea, and neutropenia. As a result, dosing recommendations have changed from high dosage loading every 3 weeks to lower dosage loading weekly. We describe a method that can be used for therapeutic drug monitoring of docetaxel levels using turbulent flow liquid chromatography electrospray tandem mass spectrometry (TFC-HPLC-ESI-MS/MS). The method is rapid, requiring only 6.3 min per analytical run following a simple protein crash. The method requires only 100 μL of serum. Concentrations of docetaxel were quantified by a calibration curve relating the peak-area ratio of docetaxel to a deuterated internal standard (docetaxel-D9). The method was linear from 7.8 to 1000 ng/mL, with imprecision ≤6.2 %. PMID:26660181

  19. Integration of continuous-flow accelerator mass spectrometry with chromatography and mass-selective detection.

    PubMed

    Flarakos, Jimmy; Liberman, Rosa G; Tannenbaum, Steven R; Skipper, Paul L

    2008-07-01

    Physical combination of an accelerator mass spectrometry (AMS) instrument with a conventional gas chromatograph-mass spectrometer (GC/MS) is described. The resulting hybrid instrument (GC/MS/AMS) was used to monitor mass chromatograms and radiochromatograms simultaneously when (14)C-labeled compounds were injected into the gas chromatograph. Combination of the two instruments was achieved by splitting the column effluent and directing half to the mass spectrometer and half to a flow-through CuO reactor in line with the gas-accepting AMS ion source. The reactor converts compounds in the GC effluent to CO2 as required for function of the ion source. With cholesterol as test compound, the limits of quantitation were 175 pg and 0.00175 dpm injected. The accuracy achieved in analysis of five nonzero calibration standards and three quality control standards, using cholesterol-2,2,3,4,4,6-d6 as injection standard, was 100 +/- 11.8% with selected ion monitoring and 100 +/- 16% for radiochromatography. Respective values for interday precision were 1.0-3.2 and 22-32%. Application of GC/MS/AMS to a current topic of interest was demonstrated in a model metabolomic study in which cultured primary hepatocytes were given [(14)C]glucose and organic acids excreted into the culture medium were analyzed. PMID:18494504

  20. Radial cold trap

    DOEpatents

    Grundy, Brian R.

    1981-01-01

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume.

  1. Radial cold trap

    DOEpatents

    Grundy, B.R.

    1981-09-29

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume. 2 figs.

  2. Continuous flow PCB radiolysis with real time assessment by gas chromatography

    SciTech Connect

    Bruce J. Mincher; Aaron Ruhter; Rene' Rodriguez; Richard Brey

    2006-05-01

    Recently, the treatment of environmentally recalcitrant pollutants such as PCBs has been studied using a number of so-called, “advanced oxidation technologies (AOTs).” As a group, the AOTs are ultimate treatment technologies that seek to mineralize the hazardous compounds to be treated (Cooper et al., 2004). One of the most versatile of the AOTs is radiolysis, usually practiced using machine-generated sources of radiation (Cooper et al., 2004, Mincher and Cooper, 2003). The radiolytic decomposition of PCBs has been reviewed (Curry and Mincher, 1999). While earlier experiments have been performed in alkaline isopropanol (Singh et al., 1985, Mucka et al., 1997), recent literature has begun to examine the radiolysis of PCBs in more “real-world” solvents, such as transformer oil (Arbon and Mincher, 1996, Mincher et al., 2000, Chaychian et al., 1999). These experiments have generally been performed in batch fashion, with small volumes of PCB-contaminated solvents placed in front of a gamma-ray source or the bremmstrahlung or e-beam of an accelerator for predetermined periods of time, to give a desired absorbed dose. These samples were then retrieved to analyze the post-irradiation PCB concentration. We report here what we believe is the first example of the radiolysis of PCBs in a process, continuous flow stream, as opposed to typical batch irradiations. The PCB-containing transformer oil was recirculated through an irradiation cell located in the path of an e-beam. Multiple passes through the cell allowed for the delivery of any desired radiation dose. This system required the development of an on-line analytical system that could provide PCB concentration values in real time. In the current experiment, a pulsed plasma electron capture detector (PDECD) was used in conjunction with a new sample preparation scheme. The new sampling scheme bypasses the need for removal or powering down of the radiation source, which would be undesirable during process PCB

  3. Simultaneous determination of aflatoxin B₁, B₂, G₁, and G₂ in corn powder, edible oil, peanut butter, and soy sauce by liquid chromatography with tandem mass spectrometry utilizing turbulent flow chromatography.

    PubMed

    Fan, Sufang; Li, Qiang; Zhang, Xiaoguang; Cui, Xiaobin; Zhang, Dongsheng; Zhang, Yan

    2015-05-01

    A novel fully automated method based on dual column switching using turbulent flow chromatography followed by liquid chromatography with tandem mass spectrometry was developed for the determination of aflatoxin B1 , B2 , G1 , and G2 in corn powder, edible oil, peanut butter, and soy sauce samples. After ultrasound-assisted extraction, samples were directly injected to the chromatographic system and the analytes were concentrated into the clean-up loading column. Through purge switching, the analytes were transferred to the analytical column for subsequent detection by mass spectrometry. Different types of TurboFlow(TM) columns, transfer flow rate, transfer time were optimized. The limits of detection and quantification of this method ranged between 0.2-2.0 and 0.5-4.0 μg/kg for aflatoxins in different matrixes, respectively. Recoveries of aflatoxins were in range of 83-108.1% for all samples, matrix effects were in range of 34.1-104.7%. The developed method has been successfully applied in the analysis of aflatoxin B1 , B2 , G1 , and G2 in real samples. PMID:25683560

  4. Revised FORTRAN program for calculating velocities and streamlines on the hub-shroud midchannel stream surface of an axial-, radial-, or mixed-flow turbomachine or annular duct. 1: User's manual

    NASA Technical Reports Server (NTRS)

    Katsanis, T.; Mcnally, W. D.

    1977-01-01

    A FORTRAN 4 computer program was developed that obtains a detailed subsonic or shock-free transonic flow solution on the hub-shroud midchannel stream surface of a turbomachine. The blade row may be fixed or rotating, and the blades may be twisted and leaned. Flow may be axial, mixed, or radial. Upstream and downstream flow variables may vary from hub to shroud, and provision is made to correct for loss of stagnation pressure. The results include velocities, streamlines, and flow angles on the stream surface as well as approximate blade surface velocities. Subsonic solutions are obtained by a finite-difference, stream-function solution. Transonic solutions are obtained by a velocity-gradient method that uses information from a finite-difference, stream-function solution at a reduced mass flow.

  5. NASA contributions to radial turbine aerodynamic analyses

    NASA Technical Reports Server (NTRS)

    Glassman, A. J.

    1980-01-01

    A brief description of the radial turbine and its analysis needs is followed by discussions of five analytical areas; design geometry and performance, off design performance, blade row flow, scroll flow, and duct flow. The functions of the programs, areas of applicability, and limitations and uncertainties are emphasized. Both past contributions and current activities are discussed.

  6. Radial head fracture - aftercare

    MedlinePlus

    Elbow fracture - radial head - aftercare ... the radius bone, just below your elbow. A fracture is a break in your bone. The most common cause of a radial head fracture is falling with an outstretched arm.

  7. Intraoperative hemodynamic evaluation of the radial and ulnar arteries during free radial forearm flap procedure.

    PubMed

    Lorenzetti, Fulvio; Giordano, Salvatore; Suominen, Erkki; Asko-Seljavaara, Sirpa; Suominen, Sinikka

    2010-02-01

    The purpose of this prospective study was to assess the blood flow of the radial and ulnar arteries before and after radial forearm flap raising. Twenty-two patients underwent radial forearm microvascular reconstruction for leg soft tissue defects. Blood flow of the radial, ulnar, and recipient arteries was measured intraoperatively by transit-time and ultrasonic flowmeter. In the in situ radial artery, the mean blood flow was 60.5 +/- 47.7 mL/min before, 6.7 +/- 4.1 mL/min after raising the flap, and 5.8 +/- 2.0 mL/min after end-to-end anastomosis to the recipient artery. In the ulnar artery, the mean blood flow was 60.5 +/- 43.3 mL/min before harvesting the radial forearm flap and significantly increased to 85.7 +/- 57.9 mL/min after radial artery sacrifice. A significant difference was also found between this value and the value of blood flow in the ulnar and radial arteries pooled together ( P < 0.05). The vascular resistance in the ulnar artery decreased significantly after the radial artery flap raising (from 2.7 +/- 3.1 to 1.9 +/- 2.2 peripheral resistance units, P = 0.010). The forearm has a conspicuous arterial vascularization not only through the radial and ulnar arteries but also through the interosseous system. The raising of the radial forearm flap increases blood flow and decreases vascular resistance in the ulnar artery. PMID:19902406

  8. Differentiating organically and conventionally grown oregano using ultraperformance liquid chromatography mass spectrometry (UPLC-MS), headspace gas chromatography with flame ionization detection (headspace-GC-FID), and flow injection mass spectrum (FIMS) fingerprints combined with multivariate data analysis.

    PubMed

    Gao, Boyan; Qin, Fang; Ding, Tingting; Chen, Yineng; Lu, Weiying; Yu, Liangli Lucy

    2014-08-13

    Ultraperformance liquid chromatography mass spectrometry (UPLC-MS), flow injection mass spectrometry (FIMS), and headspace gas chromatography (headspace-GC) combined with multivariate data analysis techniques were examined and compared in differentiating organically grown oregano from that grown conventionally. It is the first time that headspace-GC fingerprinting technology is reported in differentiating organically and conventionally grown spice samples. The results also indicated that UPLC-MS, FIMS, and headspace-GC-FID fingerprints with OPLS-DA were able to effectively distinguish oreganos under different growing conditions, whereas with PCA, only FIMS fingerprint could differentiate the organically and conventionally grown oregano samples. UPLC fingerprinting provided detailed information about the chemical composition of oregano with a longer analysis time, whereas FIMS finished a sample analysis within 1 min. On the other hand, headspace GC-FID fingerprinting required no sample pretreatment, suggesting its potential as a high-throughput method in distinguishing organically and conventionally grown oregano samples. In addition, chemical components in oregano were identified by their molecular weight using QTOF-MS and headspace-GC-MS. PMID:25050447

  9. Applying Chromatography.

    ERIC Educational Resources Information Center

    Klein, Jessie W.; Patev, Paul

    1998-01-01

    Presents three experiments to introduce students to different kinds of chromatography: (1) paper chromatography; (2) gel filtration chromatography; and (3) reverse-phase liquid chromatography. Written in the form of a laboratory manual, explanations of each of the techniques, materials needed, procedures, and a glossary are included. (PVD)

  10. On-line stop-flow two-dimensional liquid chromatography-mass spectrometry method for the separation and identification of triterpenoid saponins from ginseng extract.

    PubMed

    Wang, Shuangyuan; Qiao, Lizhen; Shi, Xianzhe; Hu, Chunxiu; Kong, Hongwei; Xu, Guowang

    2015-01-01

    A method based on stop-flow two-dimensional liquid chromatography coupled with electrospray ionization mass spectrometry (2D LC-ESI MS) was established and applied to analyze triterpenoid saponins from the main root of ginseng. Due to the special structure of triterpenoid saponins (they contain polar sugar side chains and nonpolar aglycones), hydrophilic interaction chromatography (HILIC) and reversed-phase liquid chromatography (RPLC) were used for the two dimensions, respectively. A trap column was used to connect the two dimensions. The dilution effect, which is one of the main shortcomings of traditional comprehensive 2D LC methods, was largely avoided. The peak capacity of this system was 747 and the orthogonality was 56.6 %. Compared with one-dimensional HILIC or RP LC MS analysis, 257 and 185 % more mass spectral peaks (ions with intensities that were higher than 1,000) were obtained from the ginseng main root extracts, and 94 triterpenoid saponins were identified based on MS(n) information and summarized aglycone structures. Given its good linearity and repeatability, the established method was successfully applied to classify ginsengs of different ages (i.e., years of growth), and 19 triterpenoid saponins were found through statistical analysis to vary in concentration depending on the age of the ginseng. PMID:25410638