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1

Comparison of axial and radial flow chromatography on protein separation speed and resolution  

Microsoft Academic Search

Fluid dynamic behavior, particularly the relationship between pressure drop and liquid flowrate, inside an axial and a radial\\u000a flow Chromatographic column packed with compressible porous media was theoretically analyzed using the modified Kozeny-Carman\\u000a equation. The results were compared with experimental observations obtained using compressible DEAE-agarose as a model medium.\\u000a At the 2–9 psi pressure drop range studied, theoretical derivation accounting

Yun-Ha Kim; Eun Kyu Lee

1996-01-01

2

Generalized radial flow in synthetic flow systems.  

PubMed

Traditional analysis methods used to determine hydraulic properties from pumping tests work well in many porous media aquifers, but they often do not work in heterogeneous and fractured-rock aquifers, producing non-plausible and erroneous results. The generalized radial flow model developed by Barker (1988) can reveal information about heterogeneity characteristics and aquifer geometry from pumping test data by way of a flow dimension parameter. The physical meaning of non-integer flow dimensions has long been a subject of debate and research. We focus on understanding and interpreting non-radial flow through high permeability conduits within fractured aquifers. We develop and simulate flow within idealized non-radial flow conduits and expand on this concept by simulating pumping in non-fractal random fields with specific properties that mimic persistent sub-radial flow responses. Our results demonstrate that non-integer flow dimensions can arise from non-fractal geometries within aquifers. We expand on these geometric concepts and successfully simulate pumping in random fields that mimic well-test responses seen in the Culebra Dolomite above the Waste Isolation Pilot Plant. PMID:23198816

Bowman, Dale O; Roberts, Randall M; Holt, Robert M

2013-01-01

3

Parameter identification in radial flow  

NASA Astrophysics Data System (ADS)

The classical inverse parameter identification problem is solved using an indirect method. This method is based on the minimization of an objective function or error criterion consisting of three parts: 1) least-squares error of head residuals; 2) prior information of flow parameters; and 3) regularization. An adjoint equation is incorporated into the method to eliminate the need to differentiate the heads with respect to the parameters being identified, increasing the stability of the algorithm. This method is applied to a radial coordinate system used for describing an anisotropic confined aquifer. A variable implicit finite difference method is used for predicting hydraulic heads given a continuous set of flow parameters. The method is tested using synthetic data and is found to give estimates which are both stable and unique.

Hudspeth, R. T.; Guenther, R. B.; Roley, K. L.; McDougal, W. G.

4

Boiling Radial Flow in Fractures of Varying  

E-print Network

SGP-TR-166 Boiling Radial Flow in Fractures of Varying Wall Porosity Robb Allan Barnitt June 2000 and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed. The experimental study involved boiling radial flow in a simulated fracture, bounded by a variety of materials

Stanford University

5

Stirling Engine With Radial Flow Heat Exchangers  

NASA Technical Reports Server (NTRS)

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.

Vitale, N.; Yarr, George

1993-01-01

6

Transonic throat flow in radial or nearly radial supersonic nozzles  

E-print Network

general non- symmetric, inclined radial nozzle with n =2. 0, ( inward flow) 37 4 Mach number contours with n=0. 0 and Rc/D=1. 0 . . 42 5 Mach number contours with n=1. 0 and Rc/D=1. 0 6 Mach number contours with n=2. 0 and R /D=1. 0 7 Mach number... are gathered and equated resulting in the following two sets of equations 3u 3v n n 0 3y 3z (n = 1, 2, 3, . . . ) (26) -2ui ? + ? + Sq = 0 (n = 1) 3ui 3vq 3z 3y 3u 3v n 3uq n -2uI ? ? 2u ? + gz n 3z 3y (27) (28) f (u~, vq, . . . , u , , v , ) (n = 2 3...

Carroll, Bruce Frederick

2012-06-07

7

Radial slot flows in solid rocket motors  

Microsoft Academic Search

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

J. H. Hilbing; S. D. Heister

1993-01-01

8

Non-adiabatic radial-flow reactor for styrene production  

Microsoft Academic Search

A non-adiabatic radial reactor is proposed to carry out the dehydrogenation of ethylbenzene to styrene. Radial flow and continuous heating (using superheated steam) are the main features of the new design. Steam used as heating medium flows through tubes, which are radially installed in the catalyst bed. By means of steady-state simulations, this new design has been compared with two

A. A. Savoretti; D. O. Borio; V. Bucalá; J. A. Porras

1999-01-01

9

Radial slot flows in solid rocket motors  

NASA Astrophysics Data System (ADS)

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.

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

1993-06-01

10

Low cost, radial flow, solid oxide fuel cell  

NASA Astrophysics Data System (ADS)

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. The object of this phase was to demonstrate feasibility of multi-cell stack operation. Performance milestone was 15% DC HHV efficiency with hydrogen at greater than 50 mW/sq cm over 100 h.

Petrik, M. A.

11

Stratified Taylor-Couette Flow with Radial Gravity  

Microsoft Academic Search

An experiment to study stratified Taylor-Couette flow with radial, or cross-stream, gravity is being developed. The experiment uses ferromagnetic fluid (ferrofluid) and a unique stacked-magnet configuration to generate a strong (3 to 10 g) radial gravity field. In the microgravity environment this experiment will permit laboratory study of a wide range of stability, transitional, and turbulent flow problems in a

John Hart; Dan Ohlsen; Randall P. Tagg; Patrick D. Weidman

2002-01-01

12

Toroidal flow and radial particle flux in tokamak plasmas  

NASA Astrophysics Data System (ADS)

Many effects influence toroidal flow evolution in tokamak plasmas. Momentum sources and radial plasma transport due to collisional processes and microturbulence-induced anomalous transport are usually considered. In addition, toroidal flow can be affected by nonaxisymmetric magnetic fields; resonant components cause localized electromagnetic toroidal torques near rational surfaces in flowing plasmas and nonresonant components induce "global" toroidal flow damping torque throughout the plasma. Also, poloidal magnetic field transients on the magnetic field diffusion time scale can influence plasma transport. Many of these processes can also produce momentum pinch and intrinsic flow effects. This paper presents a comprehensive and self-consistent description of all these effects within a fluid moment context. Plasma processes on successive time scales (and constraints they impose) are considered sequentially: compressional Alfvén waves (Grad-Shafranov equilibrium and ion radial force balance), sound waves (pressure constant along a field line and incompressible flows within a flux surface), and ion collisions (damping of poloidal flow). Finally, plasma transport across magnetic flux surfaces is induced by the many second order (in the small gyroradius expansion) toroidal torque effects indicated above. Nonambipolar components of the induced particle transport fluxes produce radial plasma currents. Setting the flux surface average of the net radial current induced by all these effects to zero yields the transport-time-scale equation for evolution of the plasma toroidal flow. It includes a combination of global toroidal flow damping and resonant torques induced by nonaxisymmetric magnetic field components, poloidal magnetic field transients, and momentum source effects, as well as the usual collision- and microturbulence-induced transport. On the transport time scale, the plasma toroidal rotation determines the radial electric field for net ambipolar particle transport. The ultimate radial particle transport is composed of intrinsically ambipolar fluxes plus nonambipolar fluxes evaluated at this toroidal-rotation-determined radial electric field.

Callen, J. D.; Cole, A. J.; Hegna, C. C.

2009-08-01

13

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

ERIC Educational Resources Information Center

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…

Ondrus, Martin G.; And Others

1983-01-01

14

Study of radial compression high-performance liquid chromatographic columns for preparative chromatography  

Microsoft Academic Search

The operating characteristics and efficiency of a preparative-scale, radial compression chromatograph are studied. Two commercial C18 silica packings are used, one irregular and one spherical and monodispersed. For each packing, the relationship between mobile phase flow-rate, column backpressure, and radial compression pressure is determined. A model is proposed to explain this relationship and determine the radial compression pressure needed to

David P. Gervais; W. Scott Laughinghouse; Giorgio Carta

1995-01-01

15

A theory for radial jet reattachment flow  

E-print Network

. , "Reattachment of a Two- Dimensional, Incompressible Jet to an Adjacent Flat Pl t ", A t' 1 ~tl V l. Il, pp. 291 ? 232, 1960. 12. Sawyer, R. A. , MTwo-Dimensional Reattaching Jet Flows Including Effects of Curvature on Entrainment, " Journal f Pl 'd M h V 1.... , "Reattachment of a Two- Dimensional, Incompressible Jet to an Adjacent Flat Pl t ", A t' 1 ~tl V l. Il, pp. 291 ? 232, 1960. 12. Sawyer, R. A. , MTwo-Dimensional Reattaching Jet Flows Including Effects of Curvature on Entrainment, " Journal f Pl 'd M h V 1...

Hadden, Lynne Loise

2012-06-07

16

The vergence eye movements induced by radial optic flow  

PubMed Central

Radial optic flow applied to large random dot patterns is known to elicit horizontal vergence eye movements at short latency, expansion causing convergence and contraction causing divergence: the Radial Flow Vergence Response (RFVR). We elicited RFVRs in human subjects by applying radial motion to concentric circular patterns whose radial luminance modulation was that of a square wave lacking the fundamental: the missing fundamental (mf) stimulus. The radial motion consisted of successive ¼-wavelength steps, so that the overall pattern and the 4n+1 harmonics (where n=integer) underwent radial expansion (or contraction), whereas the 4n-1 harmonics—including the strongest Fourier component (the 3rd harmonic)—underwent the opposite radial motion. Radial motion commenced only after the subject had fixated the center of the pattern. The initial RFVRs were always in the direction of the 3rd harmonic, e.g., expansion of the mf pattern causing divergence. Thus, the earliest RFVRs were strongly dependent on the motion of the major Fourier component, consistent with early spatio-temporal filtering prior to motion detection, as in the well-known energy model of motion analysis. If the radial mf stimulus was reduced to just two competing harmonics—the 3rd and 5th—the initial RFVRs showed a nonlinear dependence on their relative contrasts: when the two harmonics differed in contrast by more than about an octave then the one with the higher contrast completely dominated the RFVRs and the one with lower contrast lost its influence: winner-take-all. We suggest that these nonlinear interactions result from mutual inhibition between the mechanisms sensing the motion of the different competing harmonics. If single radial-flow steps were used, a brief inter-stimulus interval resulted in reversed RFVRs, consistent with the idea that the motion detectors mediating these responses receive a visual input whose temporal impulse response function is strongly biphasic. Lastly, all of these characteristics of the RFVR, which we attribute to the early cortical processing of visual motion, are known to be shared by the Ocular Following Response (OFR)—a conjugate tracking (version) response elicited at short-latency by linear motion—and even the quantitative details are generally very similar. Thus, although the RFVR and OFR respond to very different patterns of global motion—radial vs. linear—they have very similar local spatiotemporal properties as though mediated by the same low-level, local-motion detectors, which we suggest are in the striate cortex. PMID:17706738

Kodaka, Y.; Sheliga, B. M.; FitzGibbon, E. J.; Miles, F. A.

2007-01-01

17

Numerical Simulation on Flow in Column Chromatography  

NASA Astrophysics Data System (ADS)

Monolithic columns have attracted much attention as a novel platform for high throughput analysis, but there is little information about the fluid profile in the flow channels. In this paper, we presented our approach for the fluid simulation in column chromatography by the lattice Boltzmann method (LBM). To simulate the monolithic column system, the calculation domain was modeled by the 3D channel flow through sphere obstacles. Several types of porous structure were used, with uniform and nonuniform pores. Based on the simulations results, we discussed fluid flow and pressure variation for the optimization of the suitable structure for HPLC system.

Yamamoto, Kazuhiro; Komiyama, Ryo; Umemura, Tomonari

2013-12-01

18

Radial Plasma Flow Switch on GIT-12 Generator  

SciTech Connect

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.

Chaikovsky, S.A.; Kokshenev, V.A.; Rousskikh, A.G.; Shishlov, A.V.; Fedunin, A.V.; Labetsky, A.Yu.; Kurmaev, N.E.; Fursov, F.I. [Institute of High Current Electronics, 2/3 Akademichesky Ave., Tomsk, 634055 (Russian Federation)

2006-01-05

19

A radial temperature gradient in swirling gas flow  

Microsoft Academic Search

Gas-dynamic relations for the hypothesis of vortex interactions are analyzed together with the principal equations of the molecular-kinetic theory for gases. The analysis yields expressions for calculating radial temperature distribution in swirling gas flow. The calculated results are found to be in satisfactory agreement with the experimental data.

L. M. Dyskin; P. T. Kramarenko

1983-01-01

20

Parameter Estimation of Transmissivity Fields with Non-radial Flow Dimensions  

Microsoft Academic Search

Non-radial flow signatures are seen in many hydraulic tests in fractured media. The generalized radial flow approach, which uses a variable flow dimension (n) to incorporate changing cross-sectional area of flow, is increasingly used to account for non-radial flow in hydraulic test interpretation. Representing non-radial flow in a 2-D numerical model has been problematic. As part of an effort to

D. O. Bowman; R. M. Roberts; R. M. Holt

2008-01-01

21

Onset of radial flow in p+p collisions  

E-print Network

It has been debated for decades whether hadrons emerging from p+p collisions exhibit collective expansion. The answer is hindered by 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 \\sqrt{s}=900 GeV. At LHC higher energy of 7 TeV in p+p collisions, the radial flow velocity achieves an average value of = 0.337 +/- 0.006. This flow velocity is comparable to that in peripheral (40-60%) Au+Au collisions at RHIC.

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

2013-12-16

22

Solute transport in divergent radial flow with multistep pumping  

NASA Astrophysics Data System (ADS)

An efficient approach is developed to analytically evaluate solute transport in a horizontal, divergent radial flow field with a multistep injection flow rate and an arbitrary input concentration history. By assuming a piecewise steady state flow and transforming the time domain to the cumulative injected flow domain, the concentration distribution is found to be completely determined by the total volume of injected flow and independent of specific flow rates. Thus, on the cumulative flow domain, the transport problem with a temporally varying velocity field can be transformed into a steady state flow problem. Linear convolution can then be applied on the cumulative injected flow domain to evaluate the solution for an arbitrarily time-dependent input concentration. Solutions on the regular time domain can be conveniently obtained by mapping the solution on the cumulative injected flow domain to the time domain. Furthermore, we theoretically examine the conditions for the assumption of piecewise steady state flow to be valid. On the basis of the critical time scale of the "pseudosteady state condition," defined as when velocity changes accomplish 99% of their steady state differences, and the relative error in the mean travel time of plume front, we obtain conditions for neglecting the transitional period between two pumping steps. Such conditions include the following: (1) the duration of a pumping step, tp, must be longer than the critical time scale, tc, i.e., tp ? tc = 25r2S/T, where r is the radial distance, S is the storage coefficient, and T is the transmissivity, or similarly, a maximum problem domain needs to be defined for a given pumping strategy. (2) the maximum well pumping rate, qmax, should satisfy qmax ? ??T/25S, where ? is the effective porosity. When both conditions are satisfied, transitional periods may be neglected.

Chen, Yiming; Lu, Chunhui; Luo, Jian

2012-02-01

23

Radial flow permeability testing of an argillaceous limestone.  

PubMed

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

Selvadurai, A P S; Jenner, L

2013-01-01

24

Dynamics of particulate flow through radial-flow compressor and annular combustor  

SciTech Connect

A theoretical study is presented of the particulate flows through a radial-flow compressor with two different-size splitters and an annular combustion chamber. Three elements of the radial-flow compressor are investigated, namely: the inlet part, the impeller with the two splitter, and the vaneless diffuser. For the annular combustion chamber, only the chamber is of concern. The three-dimensional flow-field analysis for the radial-flow compressor is presented with the corresponding solid-particle trajectories through the compressor. The well-known theory describing the particles' motion in a gas flow media is applied with accurate representation of the particle-trajectory paths. This accuracy is achieved by solving the three-dimensional flow field through the compressor. One new design concept is suggested for the radial-flow compressor with splitters. This concept is that the tangential spacing of the splitters with the full blades is selected on non-equally spaced basis with the spacing being equal at the impeller exit such that the flow rate is equally splitted among different channels in the cascade. In addition, a study of the particulate flows through the annular combustor is investigated. The nature of the flow in the combustor is three-dimensional turbulent and with reacting recirculating-flow characteristics.

Elfeki, S.H.

1987-01-01

25

Multiphase flow modeling in centrifugal partition chromatography.  

PubMed

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

Adelmann, S; Schwienheer, C; Schembecker, G

2011-09-01

26

A New Power Flow Method in Radial Distribution Systems  

NASA Astrophysics Data System (ADS)

In this paper, a new efficient method is proposed for power flow calculation in radial distribution systems. The distribution busines is changing the need to plan and respond to technical change, growth in distributed generation and deregulated power markets. Thus, it is important to improve fundamental analytical tools in distribution systems. This paper proposes a new method for the power flow calculation in distribution systems. The Newton-Raphson method does not work in some distribution systems. As a result, DistFlow that focuses on the network topology was developed to overcome the problem. However, there is still room for improvement in terms of computational efficiency. In this paper, a method is proposed to improve the efficiency in creating the Jacobian.

Ohyoshi, Wataru; Mori, Hiroyuki

27

Radial Hydraulic Flow Testing of an Argillaceous Limestone  

NASA Astrophysics Data System (ADS)

This thesis describes the use of both steady state and transient radial flow tests for determining the permeability of the argillaceous Lindsay Limestone. The results obtained from this research investigation are compared with data available in the literature for similar argillaceous limestones found in the Lindsay (Cobourg) formation. The efficiency and consistency of the transient and steady state results show computational modeling using finite element programs such as COMSOL Multiphysics(TM) can be used, under the appropriate meshing scheme, to analyse test results on low permeability geomaterials. The results give a permeability range between 1x10 -22 m2 to 1.68 x 10-19 m 2 with flow along the bedding plane under unconfined conditions. The permeability of the Lindsay Limestone is of importance in understanding and predicting radionuclide spread within a proposed Deep Ground Repository for storing radioactive waste.

Jenner, Luc

28

Optimization of a Radial Flow Heat Sink Under Natural Convection  

NASA Astrophysics Data System (ADS)

A steady-state three-dimensional numerical model is developed to predict natural convection heat transfer from a radial flow heat sink. The considered medium is air. The effect of several design parameters, such as the fin length and height, number of fins, and the heat sink base radius, on heat transfer is investigated. The Taguchi method, known to be a very useful tool for selecting the best levels of control factors, is employed. Five factors and four levels for each factor are chosen. Sixteen kinds of models are analyzed, and the total heat transfer for each model is obtained. The results are used to estimate the optimum design values of the parameters affecting the heat sink performance. The reliability of these values is verified. The average heat transfer rate of the optimum model is shown to increase by 60% as compared to the reference model. Finally, the heat transfer data at different outer radii of the radial flow heat sink are correlated.

Bhowmik, Himangshu

2014-01-01

29

Instability of the radial flow over a rotating disk in a separated edgewise stream  

NASA Astrophysics Data System (ADS)

We present velocity field measurements showing the instability of the radial flow over a rotating disk in a separated flow due to an edgewise freestream. A uniform edgewise stream significantly modifies the radial jet profile. Under separated flow conditions, co-rotating vortical structures form at the edge of the radial jet layer. The results establish that the discrete structures formed in the breakup of the radial flow layer on a rotor blade in retreating blade stall are also seen in the case of flow over a rotating disk.

Raghav, Vrishank; Komerath, Narayanan

2013-11-01

30

Boiling radial flow in fractures of varying wall porosity  

SciTech Connect

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.

Barnitt, Robb Allan

2000-06-01

31

Flow field analysis of radial and backswept centrifugal compressor impellers. I - Flow measurements using a laser velocimeter  

Microsoft Academic Search

The internal flow in 2 centrifugal impellers with radial and backswept discharge, but otherwise identical design, has been investigated at tip speeds of 300 m\\/s. A laser velocimeter was applied for a detailed flow analysis, in addition to conventional flow probing and instantaneous wall pressure recordings. While the inducer flow patterns develop similarly up to a 3D flow separation at

D. Eckardt

1979-01-01

32

Study of the operating conditions of radial compression columns in preparative chromatography  

Microsoft Academic Search

Performance and stability were tested for radial compression columns packed with spherical particles of an octadecyl bonded silica. The performance of the radial columns remained unchanged after approximately 500 h of constant use, including a number of solvent gradient runs. The performance of analytical columns packed with the same material was comparable to that of the radial columns. The column

Matilal Sarker; Tong Yun; Georges Guiochon

1996-01-01

33

A difference equation model for radial flow at small Reynolds number  

E-print Network

for a thin ch~. nel radial diffussr with special attention . -. . ivcn to the radial pressure distribution =t extremely low Peynolds number. It has been noted th=t pressures less than srmt 'ent pressure are produced ir. radial flow s. t low Peynclds... rum'ocr even though t1 e gas supplied is at a hidher scarce pressure then the ambient pressure. This study is aimed at determining the radial flow criteria required to produce this sucticn cordition. The ir ter=-st in developing a solution f...

Goldsberry, Fred Lynn

2012-06-07

34

The vergence eye movements induced by radial optic flow: Some fundamental properties of the underlying local-motion detectors  

Microsoft Academic Search

Radial optic flow applied to large random dot patterns is known to elicit horizontal vergence eye movements at short latency, expansion causing convergence and contraction causing divergence: the Radial Flow Vergence Response (RFVR). We elicited RFVRs in human subjects by applying radial motion to concentric circular patterns whose radial luminance modulation was that of a square wave lacking the fundamental:

Y. Kodaka; B. M. Sheliga; E. J. FitzGibbon; F. A. Miles

2007-01-01

35

Computational investigations of axial and radial flow compressor aeromechanics  

NASA Astrophysics Data System (ADS)

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 the impeller blade excitation are elucidated, and promising directions for future research are identified.

Ramakrishnan, Kishore

36

Buoyancy-driven flow reversal phenomena in radially rotating serpentine ducts  

SciTech Connect

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.

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

2000-02-01

37

Flow control by combining radial pulsation and rotation of a cylinder in uniform flow  

NASA Astrophysics Data System (ADS)

Flow visualizations and hot-wire measurements are carried out to study a circular cylinder undergoing simultaneous radial pulsation and rotation and placed in a uniform flow. The Reynolds number is in the range of 1,000--22,000, for which transition in the shear layers and near wake is expected. Our previous experimental and numerical investigations in this subcritical flow regime have established the existence of an important energy transfer mechanism from the mean flow to the fluctuations. Radial pulsations cause and enhance that energy transfer. Certain values of the amplitude and frequency of the pulsations lead to negative drag (i.e. thrust). The nonlinear interaction between the Magnus effect induced by the steady rotation of the cylinder and the near-wake modulated by the bluff body's pulsation leads to alteration of the omnipresent Kármán vortices and the possibility of optimizing the lift-to-drag ratio as well as the rates of heat and mass transfer. Other useful applications include the ability to enhance or suppress the turbulence intensity, and to avoid the potentially destructive lock-in phenomenon in the wake of bridges, electric cables and other structures.

Oualli, H.; Hanchi, S.; Bouabdallah, A.; Gad-El-Hak, M.

2008-11-01

38

Turbulence measurements in a flow generated by the collision of radially flowing wall jets  

NASA Astrophysics Data System (ADS)

Early results of an experimental investigation of the abnormally high turbulence level and mixing layer growth rate characteristics found in the upwash regions of aircraft with vertical short takeoff and landing (V/STOL) flows in ground effect are presented. The upwash flow is formed from the collision of two opposing radially flowing wall jets. The wall jets are created in a unique way that allows the upwash to form without any interference due to the source jets. The objective of this work is to systematically characterize the development and structure of the flow. The upwash flow exhibits very large mixing rates compared to turbulent free or wall jet flows. A unique set of two component velocity profiles was taken in the upwash flow field. These measurements include several higher moment terms that appear in the turbulent kinetic energy equations, as well as length scales and intermittency determinations. Measurements were taken' along the axis connecting the two source jets as well as off this axis at six measurement stations above ground. The results provide detailed data on an important class of flows where none existed, and they are expected to significantly improve the computational empirical tools available for predicting V/STOL behavior near the ground.

Gilbert, B.

1989-11-01

39

Effective Thermal Conductivity in a Radial-Flow Packed-Bed Reactor  

Microsoft Academic Search

In this work a theoretical and experimental study of the heat transfer process in a radial flow reactor was carried out under steady- and non-steady-state conditions in order to determine the effective thermal conductivity (ke). One of the mathematical models proposed was a pseudohomogeneous model in which the effective thermal conductivity varies with radial position. The second model studied was

J. Fuentes; F. Pironti; A. L. López de Ramos

1998-01-01

40

An Efficient Localized Radial Basis Function Meshless Method for Fluid Flow and Conjugate Heat Transfer  

Microsoft Academic Search

A localized radial basis function (RBF) meshless method is developed for coupled viscous fluid flow and convective heat transfer problems. The method is based on new localized radial-basis function (RBF) expansions using Hardy Multiquadrics for the sought-after unknowns. An efficient set of formulae are derived to compute the RBF interpolation in terms of vector products thus providing a substantial computational

Eduardo Divo; Alain J. Kassab

2007-01-01

41

Radial artery flow-through graft: A new conduit for limb salvage  

Microsoft Academic Search

Objective Patients with severe peripheral occlusive disease may present especially challenging problems because of previous bypass surgery, location of ulcers, or extremely poor runoff. We used the radial artery with its overlying skin flap as a bypass conduit, called the radial artery flow-through (RAFT) graft in 10 such patients. Methods From November 1999 to January 2002, 10 patients had limb-threatening

Victoria J. Teodorescu; Jin K. Chun; Nicholas J. Morrisey; Peter L. Faries; Larry H. Hollier; Michael L. Marin

2003-01-01

42

Radial gas flow in the upper shaft and its influence on blast furnace performance  

SciTech Connect

Knowledge of and control of gas flow in the upper shaft and over the blast furnace radius is an important factor for constant optimization of blast furnace performance in terms of fuel consumption and productivity. Radial gas flow in the blast furnace is generally controlled by the radial distribution of burden and coke. However, there are other influencing variables which determine radial gas flow, in particular central gas flow: (a) Increased sinter degradation displaces the cohesive zone downwards, constricting the gas flow between the dead man and the cohesive zone. This hinders central gas flow. (b) Lower coke strengths also lead to deterioration in gas flow between the dead man and the cohesive zone and hence to decline in central gas flow. (c) Decreasing coke layers in the blast furnace hinder central gas flow. (d) Increasing coal injection rates produce higher coke degradation in the blast furnace and hence also hinder central gas flow. (e) High coal rates and lower CSR values lead to shortening of combustion zone, which hinders the gas flow to the blast furnace center. (f) Finally, increasing hot metal-slag levels divert the gas to the outside. As the significance of the question of the central gas flow is growing,and because radial gas flow at Thyssen Stahl AG can only be measured sporadically with an in-burden probe, an inclined probe (inclination 35{degree}) just above the stock line was developed for simultaneous temperature measurement and gas sampling at 9 points along the radius.

Beppler, E.; Kowalski, W.; Langner, K.; Wachsmuth, H. [Thyssen Stahl AG, Duisburg (Germany)

1996-12-31

43

Capillary chromatography based on tube radial distribution of aqueous-organic mixture carrier solvents.  

PubMed

A capillary chromatography system was developed using open capillary tubes made of fused-silica, polyethylene, or poly(tetrafluoroethylene), and an aqueous-organic mixture (water-acetonitrile-ethyl acetate mixture) as a carrier solution. Model analyte mixture solutions, such as 2,6-naphthalenedisulfonic acid and 1-naphthol, Eosin Y and perylene, bis[N,N-bis(carboxymethyl)aminomethyl]fluorescein and 1,1'-bi-2-naphthol, and 2,7-naphthalenedisulfonic acid and p-nitroaniline, were injected into the capillary tube by a gravity method. The analyte solutions were subsequently delivered through the capillary tube with the carrier solution by a micro-syringe pump. The system worked under laminar flow conditions. The analytes were separated through the capillary tube and detected on-capillary by an absorption detector. For example, 2,6-naphthalenedisulfonic acid and 1-naphthol were detected in this order with a carrier solution of water-acetonitrile-ethyl acetate (volume ratio 15:3:2), while they were detected in the reverse order with a carrier solution of water-acetonitrile-ethyl acetate (volume ratio 2:9:4). The other analyte solutions were similarly separated by the system. The elution times of the analytes could be easily reversed by changing the component ratio of the solvents in the carrier solution. PMID:19635369

Jinno, Naoya; Itano, Minoru; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

2009-10-15

44

Flow field characteristics of a radial jet reattaching on a flat plate  

E-print Network

FLOW FIELD CHARACTERISTICS OF A RADIAL JET REATTACHING ON A FLAT PLATE A Thesis by JANIQUE SYLVIA CARBONE Submitted to the Graduate College of Texas A6M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 1988 Major Subject: Aerospace Engineering FLOW FIELD CHARACTERISTICS OF A RADIAL JET REATTACHING ON A FLAT PLATE A Thesis JANIQUE SYLVIA CARBONE Approved as to style and content by: Cyrus Ostowari (Chair of Committee) Robert H. Page...

Carbone, Janique Sylvia

2012-06-07

45

A finite element viscous flow analysis in a radial turbine scroll  

E-print Network

A FINITE ELEMENT VISCOUS FLOW ANALYSIS IN A RADIAL TURBINE SCROLL A Thesis DONALD LEE HILL JR. Submitted to the Graduate College. of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December... 1987 Major Subject: Mechanical Engineering A FINITE ELEMENT VISCOUS FLOW ANALYSIS IN A RADIAL TURBINE SCROLL A Thesis by DONALD LEE HILL JR. Approved as to style snd content by: Dr. Erian A. Baskharone (Chairman of Conunittee) Dr. Alan B azzolo...

Hill, Donald Lee

2012-06-07

46

Radial Gas Flows in Colliding Galaxies: Connecting Simulations and Observations  

Microsoft Academic Search

We investigate the detailed response of gas to the formation of transient and long-lived dynamical structures induced in the early stages of a disk-disk collision and identify observational signatures of radial gas inflow through a detailed examination of the collision simulation of an equal-mass bulge-dominated galaxy. Our analysis and discussion mainly focuses on the evolution of the diffuse and dense

Daisuke Iono; Min S. Yun; J. Christopher Mihos

2004-01-01

47

Radial Gas Flows in Colliding Galaxies: Connecting Simulations and Observations  

Microsoft Academic Search

(abridged) We investigate the detailed response of gas to the formation of\\u000atransient and long-lived dynamical structures induced in the early stages of a\\u000adisk-disk collision, and identify observational signatures of radial gas inflow\\u000athrough a detailed examination of the collision simulation of an equal mass\\u000abulge dominated galaxy. Stars respond to the tidal interaction by forming both\\u000atransient arms

Daisuke Iono; Min S. Yun; J. Christopher Mihos

2004-01-01

48

Parameter Estimation of Transmissivity Fields with Non-radial Flow Dimensions  

NASA Astrophysics Data System (ADS)

Non-radial flow signatures are seen in many hydraulic tests in fractured media. The generalized radial flow approach, which uses a variable flow dimension (n) to incorporate changing cross-sectional area of flow, is increasingly used to account for non-radial flow in hydraulic test interpretation. Representing non-radial flow in a 2-D numerical model has been problematic. As part of an effort to understand the structuring of heterogeneous transmissivity that produces persisting non-radial flow dimensions, we generated spatially correlated binary random transmissivity fields. Simulated pumping in these fields produced delta pressures, log-derivatives, and flow dimensions similar to those observed in pumping tests conducted in fractured dolomite at the Waste Isolation Pilot Plant (WIPP) site. As the main point of interest for pumping tests is the estimation of aquifer parameters (i.e., storativity (S) and hydraulic conductivity (K)), we evaluate two methods of parameter estimation in our binary random fields: a variable geometry approach and a variable K approach. We examine error in aquifer parameter estimates for each method and characterize the sources of error. Our methods may provide insight into how to better understand and apply parameter estimation techniques in similar flow systems and reveal possible pitfalls that exist in assuming radial flow geometries. Acknowledgements This research is funded by WIPP programs administered by the Office of Environmental Management (EM) of the U.S. Department of Energy. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Bowman, D. O.; Roberts, R. M.; Holt, R. M.

2008-12-01

49

Exact Convex Relaxation of Optimal Power Flow in Radial Networks  

E-print Network

problems in power system operation since it was proposed in 1962 [1]. The OPF problem is increasingly important for distribution networks due to the advent of distributed generation (e.g., rooftop photovoltaic flow laws can be approximated by linear equations known as the DC power flow model [2]­[4], if 1) line

Low, Steven H.

50

Nature Macmillan Publishers Ltd 1998 momentum, and so flow in radially. Such  

E-print Network

`Bondi­Hoyle' flows have very low radiation efficiencies. Melia then showed that a 10­4 -solar-mass yr­1 the purely radial flow would create a very large amount of infrared radiation, inconsistent most of the mass, and thus of the ener- gy, whereas the electrons produce most of the radiation

Columbia University

51

Transient radial flow to a well in an unconfined aquifer  

SciTech Connect

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.

Narasimhan, T.N.; Zhu, Ming.

1991-08-01

52

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

USGS Publications Warehouse

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)

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

1987-01-01

53

LDV measurements and investigation of flow field through radial turbine guide vanes  

NASA Astrophysics Data System (ADS)

The results of LDV measurements and investigation of the detailed flow field in a radial inflow turbine nozzle are presented. The flow velocities were measured at upstream, inside and downstream of the nozzle blades for two different mass flow rates, using a three-component LDV system. Results are presented as contour plots of mean velocities, flow angles and turbulence intensities. The flow field inside the nozzle blade passages were found to be strongly influenced by the upstream scroll geometry. Significant end wall cross flows and flow mixing were observed. The flow turbulence increased in the downstream flow direction. The LDV mean flow results on the blade-to-blade plane at midspan location were also compared with an inviscid, 'panel method' solution.

Eroglu, Hasan; Tabakoff, Widen

1989-06-01

54

Anomalous magnetosheath flows and distorted subsolar magnetopause for radial interplanetary magnetic fields  

NASA Astrophysics Data System (ADS)

On 12 August 2007 from 1436 to 1441 UT, when the five THEMIS probes (THA, THB, THC, THD, and THE) were located near the subsolar magnetopause, a sunward flow was observed in the magnetosheath. A fast anti-sunward flow (-280 km/s) was observed in the magnetosheath before the sunward flow. Although THA observed this fast anti-sunward flow, THC and THD, which were also in the magnetosheath, instead observed a slow flow, indicating that the fast flow was small in scale. With the observed flow vectors and the magnetopause normal directions estimated from tangential discontinuity analysis, we conclude that this fast flow creates an indentation on the magnetopause, 1 R E deep and 2 R E wide. The magnetopause subsequently rebounds, rotating the flow direction sunward along the surface of the magnetopause. The fast flow is likely related to the radial interplanetary magnetic field.

Shue, J.-H.; Chao, J.-K.; Song, P.; McFadden, J. P.; Suvorova, A.; Angelopoulos, V.; Glassmeier, K. H.; Plaschke, F.

2009-09-01

55

Anomalous Magnetosheath Flows and Distorted Subsolar Magnetopause for Radial Interplanetary Magnetic Fields  

NASA Astrophysics Data System (ADS)

On 12 August 2007 from 1436 to 1441 UT, when the five THEMIS probes (THA, THB, THC, THD, and THE) were located near the subsolar magnetopause, a sunward flow was observed in the magnetosheath. A fast anti-sunward flow (-280 km/s) was observed in the magnetosheath before the sunward flow. Although THA observed this fast anti-sunward flow, THC and THD, which were also in the magnetosheath, instead observed a slow flow, indicating that the fast flow was small in scale. With the observed flow vectors and the magnetopause normal directions estimated from tangential discontinuity analysis, we conclude that this fast flow creates an indentation on the magnetopause, 1 Re deep and 2 Re wide. The magnetopause subsequently rebounds, rotating the flow direction sunward along the surface of the magnetopause. The fast flow is likely related to the radial interplanetary magnetic field.

Shue, J.; Chao, J. K.; Song, P.; McFadden, J. P.; Suvorova, A.; Angelopoulos, V.; Glassmeier, K.; Plaschke, F.

2009-12-01

56

Three dimensional unsteady flow calculations in radial components  

NASA Astrophysics Data System (ADS)

A numerical model to predict the impeller response due to the downstream static pressure distortion caused by the volute when a centrifugal compressor works at off design conditions is presented. The three dimensional Euler equations are solved by a time marching technique allowing the evaluation of the unsteady flowfield using the finite volume space discretization and Runge-Kutta time stepping scheme. Phase lagged periodicity conditions were used in the computations of the unsteady flow upstream and downstream the blade channel. Reflecting and non-reflecting boundary conditions were tested. It was demonstrated that the latter result in faster convergence than the former. A cyclic variation of the impeller flowfield due to the donwstream static pressure non-uniform distribution is observed.

Fatsis, A.

57

Effects of Skeletonized versus Pedicled Radial Artery on Postoperative Graft Patency and Flow  

PubMed Central

Background Radial artery (RA) was the second arterial graft introduced in clinical practice for myocardial revascularization. The skeletonization technique of the left internal thoracic artery (LITA) may actually change the graft's flow capacity with potential advantages. This leads to the assumption that the behavior of the RA, as a coronary graft, is similar to that of the LITA, when skeletonized. Objective This study evaluated 'free' aortic-coronary radial artery (RA) grafts, whether skeletonized or with adjacent tissues. Methods A prospective randomized study comparing 40 patients distributed into two groups was conducted. In group I, we used skeletonized radial arteries (20 patients), and in group II, we used radial arteries with adjacent tissues (20 patients). After the surgical procedure, patients underwent flow velocity measurements. Results The main surgical variables were: RA internal diameter, RA length, and free blood flow in the radial artery. The mean RA graft diameters as calculated using quantitative angiography in the immediate postoperative period were similar, as well as the flow velocity measurement variables. On the other hand, coronary cineangiography showed the presence of occlusion in one RA graft and stenosis in five RA grafts in GII, while GI presented stenosis in only one RA graft (p = 0.045). Conclusion These results show that the morphological and pathological features, as well as the hemodynamic performance of the free radial artery grafts, whether prepared in a skeletonized manner or with adjacent tissues, are similar. However, a larger number of non-obstructive lesions may be observed when RA is prepared with adjacent tissues. PMID:24918911

Bonini, Romulo C. Arnal; Staico, Rodolfo; Issa, Mario; Arnoni, Antoninho Sanfins; Chaccur, Paulo; Abdulmassih, Camilo; Dinkhuysen, Jarbas Jackson; Paulista, Paulo Paredes; de Souza, Luiz Carlos Bento; Moreira, Luiz Felipe P.

2014-01-01

58

Laser measurements of the flow field in a radial turbine rotor  

NASA Astrophysics Data System (ADS)

Detailed measurements of an unsteady flow field within the rotor of a radial inflow turbine were performed using a three component Laser Doppler Velocimetry system together with a rotor encoder. The rotor flow field measurements are presented as relative mean velocity and turbulence stress contours at various cross sectional planes through the rotor. The cross flow and turbulence stress levels were found to be influenced by the incidence angle. Transportation of the high turbulence fluid by the cross flow was observed downstream in the rotor blade passages.

Pasin, M.; Tabakoff, W.

1993-01-01

59

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

NASA Technical Reports Server (NTRS)

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.

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

1971-01-01

60

Flow fields behind a variable-area nozzle for radial turbines  

Microsoft Academic Search

The flow fields behind a variable-area nozzle for radial turbines were measured in detail using a three-hole cobra probe in 15 cases, which are a combination of three nozzle throat areas (0.8, 1.0, and 1.4 times the rated area) and five values of the tip-clearance to blade-height ratio (between 0.0 to 0.099). The flow fields at different tip clearances are

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

1987-01-01

61

Liquid chromatography/Fourier transform IR spectrometry interface flow cell  

DOEpatents

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.

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

1985-01-04

62

Finite layer method for flow in layered radial two-zone aquifer systems.  

PubMed

A new finite layer method (FLM) is presented in this paper for transient flow analysis in layered radial two-zone aquifer systems. A radial two-zone system is an aquifer configuration in which a circular aquifer with finite radius is surrounded by a matrix possessing different permeability and storage properties. The aquifers can be pumped from fully or partially penetrating wells of infinitesimal radius. The trial function for drawdown is obtained through the use of piecewise linear correction functions in the present method. The trial function can satisfy the continuity conditions of flow and possess an appropriate continuity of C(0) at the two-zone interface. On the basis of Galerkin's method and the continuity condition of flow, the finite layer formulation is derived. The proposed method can cope with the anisotropy and layered heterogeneity in radial two-zone aquifer systems. Several numerical examples are presented to verify the validity of the present method through comparison with the analytical solution and the numerical results based on the finite difference method, in which a test of three-dimensional (3D) flow to a partially penetrating well in anisotropic two-zone aquifers is included. Furthermore, an additional application in simulating the two-zone flow in aquitard-aquifer systems is presented to demonstrate the applicability of FLM in modeling flow in more complex aquifer systems. PMID:21883187

Wang, Xudong; Xu, Jin; Cai, Zhengyin

2012-01-01

63

Turbulence-driven zonal flows in helical systems with radial electric fieldsa)  

NASA Astrophysics Data System (ADS)

Collisionless long-time responses of the zonal-flow potential to the initial condition and turbulence source in helical systems having radial electric fields are derived theoretically. All classes of particles in passing, toroidally trapped, and helical-ripple-trapped states are considered. The transitions between the toroidally trapped and helical-ripple-trapped states are taken into account while solving the gyrokinetic equation analytically by taking its average along the particle orbits. When the radial displacements of helical-ripple-trapped particles are reduced either by neoclassical optimization of the helical geometry lowering the radial drift or by strengthening the radial electric field Er to boost the poloidal rotation, enhanced zonal-flow responses are obtained. Under the identical conditions on the magnitude of Er and the magnetic geometry, using ions with a heavier mass gives rise to a higher zonal-flow response, and therefore the turbulent transport is expected to show a more favorable ion-mass dependence than the conventional gyro-Bohm scaling.

Sugama, H.; Watanabe, T.-H.

2009-05-01

64

The propagation of acoustic waves in a slowly varying duct with radially sheared axial mean flow  

NASA Astrophysics Data System (ADS)

We consider the propagation of acoustic waves along a cylindrical duct carrying radially sheared axial mean flow, in which the duct radius is allowed to vary slowly along the axis. In previous work [A.J. Cooper & N. Peake, Journal of Fluid Mechanics 445 (2001) 207-234.] radially sheared axial mean flow with nonzero swirl in a slowly varying duct was considered, but in this paper we set the swirl to zero, thereby allowing simplification of the calculations of both the mean and unsteady flows. In this approach the acoustic wavenumber and corresponding eigenfunction are determined locally, while the wave amplitude is found by solving an evolution equation along the duct. Sample results are presented, including a case in which, perhaps surprisingly, the number of cut-on modes increases as the duct radius decreases.

Lloyd, A. E. D.; Peake, N.

2013-08-01

65

Three-dimensional inviscid analysis of radial turbine flow and a limited comparison with experimental data  

NASA Technical Reports Server (NTRS)

The three-dimensional inviscid DENTON code is used to analyze flow through a radial-inflow turbine rotor. Experimental data from the rotor are compared with analytical results obtained by using the code. The experimental data available for comparison are the radial distributions of circumferentially averaged values of absolute flow angle and total pressure downstream of the rotor exit. The computed rotor-exit flow angles are generally underturned relative to the experimental values, which reflect the boundary-layer separation at the trailing edge and the development of wakes downstream of the rotor. The experimental rotor is designed for a higher-than-optimum work factor of 1.126 resulting in a nonoptimum positive incidence and causing a region of rapid flow adjustment and large velocity gradients. For this experimental rotor, the computed radial distribution of rotor-exit to turbine-inlet total pressure ratios are underpredicted due to the errors in the finite-difference approximations in the regions of rapid flow adjustment, and due to using the relatively coarser grids in the middle of the blade region where the flow passage is highly three-dimensional. Additional results obtained from the three-dimensional inviscid computation are also presented, but without comparison due to the lack of experimental data. These include quasi-secondary velocity vectors on cross-channel surfaces, velocity components on the meridional and blade-to-blade surfaces, and blade surface loading diagrams. Computed results show the evolution of a passage vortex and large streamline deviations from the computational streamwise grid lines. Experience gained from applying the code to a radial turbine geometry is also discussed.

Choo, Y. K.; Civinskas, K. C.

1985-01-01

66

Modulation of mobile phase composition in flow-injection\\/sequential-injection chromatography exploiting multisyringe flow analysis  

Microsoft Academic Search

In this paper, a time-based multicommutated flow system is proposed for appropriate selection and modulation of mobile phase\\u000a composition in flow-injection (FI)\\/sequential-injection (SI) chromatography. The novel flow assembly involves the on-line\\u000a coupling of a short monolithic reversed-phase chromatographic column with a multisyringe flow injection set-up furnished with\\u000a a set of solenoid valves. The proposed hyphenated technique was applied to the

Mailen Fernández; Manuel Miró; Hilda M. González; Víctor Cerdà

2008-01-01

67

Separation in the mixed convection boundary-layer radial flow over a constant temperature horizontal plate  

NASA Astrophysics Data System (ADS)

The boundary-layer flow of a horizontal current emerging radially from a cylindrical vertical surface of radius r0 with a constant velocity over a heated horizontal wall at constant temperature is analyzed. The boundary-layer equations are made dimensionless with a radial characteristic length in which natural and forced convection become of the same order of magnitude, so that the Prandtl (Pr) number and Gr2/Re5 are the only nondimensional parameters governing the problem, where Gr and Re are the Grashof and Reynolds numbers based on r0, respectively. A similarity solution valid at the leading edge of the boundary-layer flow is obtained. It contains, as the first order correction to Blasius' thermal boundary layer solution, the effect of buoyancy, and as the second order correction the effect of the radial divergence of the flow. This solution is used to start the numerical integration of the equations to provide a criterion for when separation occurs. It is found that separation, based on the boundary layer model, occurs for Gr < B(Pr)Re5/2, where the Prandtl's number function B is characterized numerically and found to be almost constant. This separation location law is compared with experimental results for air flowing over a heated horizontal plate at constant temperature, finding a qualitative good agreement.

Fernandez-Feria, R.; del Pino, C.; Fernández-Gutiérrez, A.

2014-10-01

68

L.D.V. measurements of unsteady flow fields in radial turbine  

NASA Astrophysics Data System (ADS)

Detailed measurements of an unsteady flow field within the inlet guide vanes (IGV) and the rotor of a radial inflow turbine were performed using a three component Laser Doppler Velocimeter (LDV) system together with a rotary encoder. The mean velocity, the flow angle and the turbulence contours for IGV passages are presented at four blade-to-blade planes for different rotor positions to give three dimensional, unsteady behavior of the IGV flow field. These results are compared with the measurements obtained in the same passage in the absence of the rotor. The flow field of the IGV passage was found to be affected by the presence of the rotor. The ratio of the tangential normal stresses to the radial normal stresses at the exit of the IGV was found to be more than doubled when compared to the case without the rotor. The rotor flow field measurements are presented as relative mean velocity and turbulence stress contours at various cross section planes throughout the rotor. The cross flow and turbulence stress levels were found to be influenced by the incidence angle. Transportation of the high turbulence fluid by the cross flow was observed downstream in the rotor blade passages.

Tabakoff, W.; Pasin, M.

1992-07-01

69

Radial granular segregation under chaotic flow in two-dimensional tumblers  

NASA Astrophysics Data System (ADS)

An initially well mixed granular material composed of two distinct subclasses of particles, small and large or light and heavy, segregates radially into stable lobed patterns when rotated in various quasi-two-dimensional, regular polygonal tumblers. The patterns are highly sensitive to the time-periodic flow, which in turn depends critically on the fill fraction and container shape. Simulations of a simple model reproduce the segregation patterns observed in experiment. Kolmogorov-Arnol’d-Moser (KAM) regions in Poincaré plots of the velocity field used to model the flow attract smaller (denser) particles and their spatial symmetries mirror those of the segregation patterns, suggesting that competition between the driving forces for radial segregation (percolation and buoyancy) and those for chaotic mixing plays a key role.

Cisar, Stephen E.; Umbanhowar, Paul B.; Ottino, Julio M.

2006-11-01

70

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

PubMed Central

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

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

2013-01-01

71

Numerical modeling of groundwater flow into a radial collector well with horizontal arms  

Microsoft Academic Search

In this study, we present a new numerical model for evaluating drawdowns in the horizontal arms of a radial collector well.\\u000a This model accounts for internal friction losses, which depend on the Reynolds number, and pipe roughness in the arms of the\\u000a collector well. It also accounts for diverse flow regimes (laminar, transitional, and turbulent) in the arms; thus, the

Eunhee Lee; Yunjung Hyun; Kang-Kun Lee

2010-01-01

72

Modeling of TIG welding and abrasive flow machining processes using radial basis function networks  

Microsoft Academic Search

Input-output relationships of tungsten inert gas (TIG) welding and abrasive flow machining (AFM) processes were determined\\u000a using radial basis function networks (RBFNs). A batch mode of training was adopted to implement the principle of back-propagation\\u000a (BP) algorithm (which works based on a steepest descent algorithm) and a genetic algorithm (GA), separately. The performances\\u000a of RBFN tuned by a BP algorithm

Asfak Ali Mollah; Dilip Kumar Pratihar

2008-01-01

73

Time-related capture zones for radial flow in two dimensional randomly heterogeneous media  

Microsoft Academic Search

.   We consider the effect of randomly heterogeneous hydraulic conductivity on the spatial location of time-related capture zones\\u000a (isochrones) for a non-reactive tracer in the steady-state radial flow field due to a pumping well in a confined aquifer.\\u000a A Monte Carlo (MC) procedure is used in conjunction with FFT-based spectral methods. The log hydraulic conductivity field\\u000a is assumed to be

M. Riva; A. Guadagnini; F. Ballio

1999-01-01

74

Revised injectivity calculations for five-spot patterns during radial flow period  

E-print Network

Developed Method . ~ 23 2. Results Using Revised. Method . . . . . . . . 24 ABSTRACT The purpose of this work was to improve the method of calculating water infection rates during the radial flow period into depleted reservoirs for five-spot patterns.... In addition, this computational method is in- tended for use with reservoirs which essentially have 'been depleted of their natural energies with a substantial amount of oil remaining in place. The recovery of oil by this type of operation is called...

Schlaudt, Robert Christian

2012-06-07

75

Transport phenomena in radial flow MOCVD reactor with three concentric vertical inlets  

NASA Astrophysics Data System (ADS)

Transport phenomena in radial flow metalorganic chemical vapor deposition (MOCVD) reactor with three concentric vertical inlets are studied by two-dimensional numerical modeling. By varying the parameters such as gas pressure, flow rates combination of multi-inlets, geometric shapes and sizes of reactor and flow distributor, temperatures of susceptor and ceiling, and susceptor rotation, the corresponding velocity, temperature, and concentration fields inside the reactor are obtained; the onset and change of flow recirculation cells under influences of those parameters are determined. It is found that recirculation cells, originated from flow separation near the bend of reactor inlets, are affected mainly by the reactor height and shape, the operating pressure, the flow rates combination of multi-inlets, and the mean temperature between susceptor and ceiling. By increasing the flow rate of mid-inlet and the mean temperature, decreasing the pressure, maintaining the reactor height below certain criteria, and trimming the bends of reactor wall and flow distributor to streamlined shape, the recirculation cells can be minimized so that smooth and rectilinear flow prevails in the susceptor region, which corresponds to smooth and rectilinear isotherms and larger reactant concentration near the susceptor. For the optimized reactor shape, the reactor size can be enlarged to diameter D=40 cm and height H=2 cm without flow recirculation. The susceptor rotation over a few hundred rpm around the reactor central axis will induce the recirculation cell near the exit and deflect the streamlines near the susceptor, which is not the case for vertical reactors.

Zuo, Ran; Zhang, Hong; Liu, Xiang-lin

2006-08-01

76

Polyethylene glycol increases purification and recovery, alters retention behavior in flow-through chromatography of hemoglobin  

Microsoft Academic Search

Flow-through chromatography was a method for purification of hemoglobin (Hb) from red cell lysate. The presence of 0–5% polyethylene glycol (PEG) increased the retention time of Hb peak from 15min to 20min in flow-through ion-exchange chromatography (IEC) but decreased the retention time from 88min to 62min in the hydrophobic interaction chromatography (HIC). However, the purification and the recovery were both

Xiuling Lu; Dongxu Zhao; Guanghui Ma; Zhiguo Su

2004-01-01

77

Numerical investigation of laminar flow and heat transfer in a radial flow cooling system with the use of nanofluids  

Microsoft Academic Search

Nanofluids, because of their enhanced heat transfer capability as compared to normal water\\/glycol\\/oil based fluids, offer the engineer opportunities for development in areas where high heat transfer, low temperature tolerance and small component size are required. In this present paper, the hydrodynamic and thermal fields of a water–?Al2O3 nanofluid in a radial laminar flow cooling system are considered. Results indicate

Gilles Roy; Cong Tam Nguyen; Paul-René Lajoie

2004-01-01

78

Unsteady flow evolution in swirl injector with radial entry. I. Stationary conditions  

NASA Astrophysics Data System (ADS)

The vortical flow dynamics in a gas-turbine swirl injector were investigated by means of large eddy simulations. The flow enters the injector through three sets of radial-entry, counter-rotating swirl vanes. The formulation treats the Favre-filtered conservation equations in three dimensions along with a subgrid-scale model, and is solved numerically using a density-based, finite-volume approach with explicit time marching. Several methods, including proper orthogonal decomposition, spectral analysis, and flow visualization, are implemented to explore the flow dynamics in the complex three-dimensional flowfields. Various underlying mechanisms dictating the flow evolution, such as vortex breakdown, the Kelvin-Helmholtz instability, and helical instability, as well as their interactions, are studied for different swirl numbers. The flowfield exhibits well-organized motion in a low swirl-number case, in which the vortex shedding arising from shear instabilities downstream of the guide vanes drives acoustic oscillations of the mixed first tangential and first radial mode. The flowfield, however, becomes much more complicated at high swirl numbers, with each sub-regime dominated by different structures and frequency contents.

Wang, Shanwu; Hsieh, Shih-Yang; Yang, Vigor

2005-04-01

79

Effect of radial transport on compressor tip clearance flow structures and enhancement of stable flow range  

E-print Network

The relation between tip clearance flow structure and axial compressor stall is interrogated via numerical simulations, to determine how casing treatment can result in improved flow range. Both geometry changes and flow ...

Nolan, Sean Patrick Rock

2005-01-01

80

Radial and vertical flows induced by galactic spiral arms: likely contributors to our `wobbly Galaxy'  

NASA Astrophysics Data System (ADS)

In an equilibrium axisymmetric galactic disc, the mean Galactocentric radial and vertical velocities are expected to be zero everywhere. In recent years, various large spectroscopic surveys have however shown that stars of the Milky Way disc exhibit non-zero mean velocities outside of the Galactic plane in both the Galactocentric radial and vertical velocity components. While radial velocity structures are commonly assumed to be associated with non-axisymmetric components of the potential such as spiral arms or bars, non-zero vertical velocity structures are usually attributed to excitations by external sources such as a passing satellite galaxy or a small dark matter substructure crossing the Galactic disc. Here, we use a three-dimensional test-particle simulation to show that the global stellar response to a spiral perturbation induces both a radial velocity flow and non-zero vertical motions. The resulting structure of the mean velocity field is qualitatively similar to what is observed across the Milky Way disc. We show that such a pattern also naturally emerges from an analytic toy model based on linearized Euler equations. We conclude that an external perturbation of the disc might not be a requirement to explain all of the observed structures in the vertical velocity of stars across the Galactic disc. Non-axisymmetric internal perturbations can also be the source of the observed mean velocity patterns.

Faure, Carole; Siebert, Arnaud; Famaey, Benoit

2014-05-01

81

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

SciTech Connect

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.

Reichert, A.W. [Siemens AG, Muellheim (Germany); Simon, H. [Univ. of Duisburg (Germany). Inst. of Turbomachinery

1997-01-01

82

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

NASA Technical Reports Server (NTRS)

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.

Heidmann, James D.; Beach, Timothy A.

1990-01-01

83

Chromatography  

NSDL National Science Digital Library

This site provides fundamental background information about chromatography, including plate theory, rate theory, the mechanisms of separations, and qualitative and quantitative aspects of chromatography. The format is a series of PowerPoint-like presentations available in PDF format.

Hardy, James K.

2011-05-16

84

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

E-print Network

On the nature of radial transport across sheared zonal flows in electrostatic ion the future ITER tokamak will operate.9 The benefits for confinement coming from the presence of sheared be accepted: that the nature of radial transport must be and remain diffu- sive. Or more precisely

Newman, David

85

Three-dimensional flow field measurements using LDV in the exit region of a radial inflow turbine  

Microsoft Academic Search

Detailed flow investigation in the downstream region of a radial inflow turbine was performed using a three component Laser Doppler Velocimeter. The flow velocities are measured in the exit region of the turbine at an off-design operating condition. The measured parameters are correlated to the rotor blade rotation to observe any periodic nature of the flow. The measurements reveal a

D. M. Murugan; W. Tabakoff; A. Hamed

1996-01-01

86

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

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

87

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

SciTech Connect

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.

Wu, Yu-Shu; Pan, Lehua

2004-02-13

88

Liquid chromatography/fourier transform ir spectrometry interface flow cell  

SciTech Connect

This patent describes a Fourier transform infrared spectrometer. A sample material is isolated by liquid chromatography and directed through an elongated tube of small inner diameter for irradiation by an infrared beam in obtaining an infrared spectrum of the sample material representing the composition thereof. A sample flow cell comprises: a generally cylindrical crystal having a longitudinal axis and a generally circular cross-section. The crystal is transparent to infrared radiation and is positioned in line with the infrared beam. Its longitudinal axis is aligned generally perpendicular to the infrared beam, whereby the infrared beam is incident upon the crystal and is focused generally on the crystal's longitudinal axis and is transmitted therethrough so as to exit therefrom; and a small diameter, linear bore having a circular cross-section positioned within the crystal along the longitudinal axis and extending the length thereof and oriented generally perpendicular to the direction of propagation of the infrared beam therein. The bore is coupled to the elongated tube for receiving and directing the sample material in the path of the infrared beam. The exiting infrared beam includes the infrared spectrum of the sample material.

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

1986-10-21

89

Instabilities of rotational flows in azimuthal magnetic fields of arbitrary radial dependence  

NASA Astrophysics Data System (ADS)

Using the Wentzel-Kramers-Brillouin (WKB) approximation we perform a linear stability analysis for a rotational flow of a viscous and electrically conducting fluid in an external azimuthal magnetic field that has an arbitrary radial profile B?(R). In the inductionless approximation, we find the growth rate of the three-dimensional perturbation in a closed form and demonstrate in particular that it can be positive when the velocity profile is Keplerian and the magnetic field profile is slightly shallower than R-1.

Kirillov, Oleg N.; Stefani, Frank; Fukumoto, Yasuhide

2014-06-01

90

Chromatography  

NSDL National Science Digital Library

This lab activity from the Biotechnology Alliance for Suncoast Biology Educators covers background information on the basic types of chromatography and has the student separate pigments extracted from pens and plant leaves using paper chromatography. The lesson includes the materials needed and the demonstration procedures.

Keirle, Matt

2012-07-10

91

A study of radial-flow turbomachinery blade vibration measurements using Eulerian laser Doppler vibrometry  

NASA Astrophysics Data System (ADS)

The structural integrity of blades is critical to the health of turbomachinery. Since operational failure of these blades can possibly lead to catastrophic failure of the machine, it is important to have knowledge of blade conditions in an online fashion. Due to several practical implications, it is desired to measure blade vibration with a non-contact technique. The application of laser Doppler vibrometry towards the vibration based condition monitoring of axial-flow turbomachinery blades has been successfully demonstrated in previous work. In this paper the feasibility of using laser Doppler vibrometry to measure radial-flow turbomachinery blade vibrations is investigated with the aid of digital image correlation and strain gauge telemetry.

Oberholster, A. J.; Heyns, P. S.

2014-05-01

92

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

NASA Technical Reports Server (NTRS)

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.

Skoe, Ivar Helge

1991-01-01

93

Theoretical analysis of incompressible flow through a radial-inlet centrifugal impeller at various weight flows  

NASA Technical Reports Server (NTRS)

A method for the solution of the incompressible nonviscous flow through a centrifugal impeller, including the inlet region, is presented. Several numerical solutions are obtained for four weight flows through an impeller at one operating speed. These solutions are refined in the leading-edge region. The results are presented in a series of figures showing streamlines and relative velocity contours. A comparison is made with the results obtained by using a rapid approximate method of analysis.

Kramer, James J; Prian, Vasily D; Wu, Chung-Hua

1956-01-01

94

Chromatography  

NSDL National Science Digital Library

In this activity, explore chromatography and the various colors that make up the ink in markers. Use this activity to investigate cohesion and adhesion. The online version of this activity is set up so that learners solve a mystery.

Boston, Wgbh

2002-01-01

95

Gyrokinetic simulation of zonal-flow response in LHD plasma with equilibrium-scale radial electric field  

NASA Astrophysics Data System (ADS)

For the anomalous transport reduction, it is important to seek a magnetic configuration with strong zonal-flow generation. The zonal-flow response is enhanced in a neoclassically-optimized helical configuration with slower radial drift of trapped particles, such as the inward-shifted LHD plasma. It is also pointed out that an equilibrium-scale radial electric field (Er) leads to further increase of zonal flows in helical systems [1]. Our gyrokinetic simulations show increase of the residual zonal flows in case with the poloidal Mach number of 0.1-0.3, and support the theoretical prediction. The residual zonal-flow amplitudes are weakly dependent on the radial wavenumbers in the inward-shifted LHD plasma, while, in case without Er, the lower residual level is found for the longer radial wavelength. In the standard LHD configuration, furthermore, the zonal-flow response shows an oscillatory behavior. It is also noteworthy that, under the identical conditions on the magnitude of Er and the magnetic geometry, using ions with a heavier mass gives rise to a higher zonal-flow response. Therefore, the turbulent transport is expected to show a more favorable ion-mass dependence than the conventional gyro-Bohm scaling.[4pt] [1] H. Sugama and T.-H. Watanabe, Phys. Plasmas 16, 056101 (2009).

Watanabe, Tomo-Hiko; Sugama, Hideo

2009-11-01

96

Solids removal from a coldwater recirculating system—comparison of a swirl separator and a radial-flow settler  

Microsoft Academic Search

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 150m3 ‘Cornell-type’ dual-drain tank during the production of food-size Arctic char and rainbow trout. The flow through the culture tank was 4500–4800L\\/min. Approximately 92–93% of the system flow exited through

John Davidson; Steven T. Summerfelt

2005-01-01

97

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

NASA Astrophysics Data System (ADS)

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.

Kan, P.

2011-12-01

98

Acoustic geometry through perturbation of mass accretion rate : I - radial flow in general static spacetime  

E-print Network

We propose a novel perturbation scheme to perform the linear stability analysis of stationary transonic integral accretion solutions corresponding to the hydrodynamic non self-gravitating radial flow of matter in a general static black hole spacetime. We demonstrate that a metric independent perturbation scheme can be developed, which leads to the emergence of the relativistic acoustic geometry and ensures the stability of the background stationary solutions. The acoustic metric obtained by perturbing the mass accretion rate rate is found to be identical with that obtained through the perturbation of the velocity potential. Our work thus makes a crucial connection between two apparently disjoint fields of study - accretion astrophysics and analogue gravity phenomena. We also formally prove that acoustic horizons never form in the Rindler spacetime.

Deepika B. Ananda; Sourav Bhattacharya; Tapas K. Das

2014-06-17

99

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

NASA Technical Reports Server (NTRS)

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.

Hart, John E.

1996-01-01

100

Chromatography  

NSDL National Science Digital Library

The North Carolina Community College System BioNetwork's interactive eLearning tools (IETs) are reusable chunks of training that can be deployed in a variety of courses or training programs. IETs are designed to enhance, not replace hands-on training. Learners are able to enter a hands-on lab experience better prepared and more confident. This particular IET delves into chromatography including the basics, the three types (affinity, ion exchange, size exclusion), and the parts and functions associated with chromatography.

2011-11-29

101

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

NASA Astrophysics Data System (ADS)

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 (?, t) where ? and t represent the fluid travel and current time, respectively. Central for this approach is the probability density function of the RSF ?that 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.

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

2012-12-01

102

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

NASA Astrophysics Data System (ADS)

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.

Ikeshita, Kazuki; Hasegawa, Hideyuki; Kanai, Hiroshi

2009-07-01

103

Multicomponent Radial Flow Chromatography T. Gu', G-J. Tsai2, and G. T. Tsao3  

E-print Network

-VerlagBerlin Heidelberg 1993 #12;T.Gu et al. List of Symbols and Abbreviations Description constant in Langmuir isotherm of Chemical Engineering, Ohio University, Athens, Ohio 45701, USA Building 130, Lederle Laboratories, Pearl

Gu, Tingyue

104

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

USGS Publications Warehouse

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.

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

2001-01-01

105

Analytical solutions of nonaqueous-phase-liquid dissolution problems associated with radial flow in fluid-saturated porous media  

NASA Astrophysics Data System (ADS)

The removal of nonaqueous phase liquids (NAPLs) from contaminated soils by means of fresh water injection through a rejection well can be treated as a fully coupled problem involving the NAPL dissolution, radial aqueous-phase-liquid flow and dissolved NAPL transport through solute advection and diffusion/dispersion. The governing equations of this coupled problem can be mathematically described by a set of simultaneous partial differential equations with variable coefficients. In the case of the NAPL dissolution ratio (which is defined as the ratio of the equilibrium concentration of the dissolved NAPL to the density of the NAPL) approaching zero, analytical solutions for the NAPL dissolution problem associated with radial aqueous-phase-liquid flow have been derived in this paper. As a direct application example, the derived analytical solutions are used to investigate the fundamental behaviours of the NAPL dissolution problems associated with radial aqueous-phase-liquid flow in the fluid-saturated porous media. The related analytical results have demonstrated that three key factors, namely the dimensionless comprehensive number (which is known as the Zhao number and can be used to represent the overall hydrodynamic characteristic of a NAPL dissolution system), the initial saturation of the residual NAPL and the dimensionless injection well radius, can have significant effects on the dimensionless NAPL dissolution front propagation speed, the dimensionless NAPL dissolution front location and dimensionless breakthrough time of the NAPL dissolution front in the NAPL dissolution system associated with radial aqueous-phase-liquid flow.

Zhao, Chongbin; Hobbs, B. E.; Ord, A.

2013-06-01

106

Chromatography  

NSDL National Science Digital Library

In this activity, by the Concord Consortium's Molecular Literacy project, students "learn about the phases of molecular separation, and then experiment with paper and ion chromatography." The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In addition, visitors will find an overview of the activity, assessments, and concepts and their correlation to AAAS and NSES standards.

2008-08-14

107

Chromatography  

NSDL National Science Digital Library

In this chemistry activity, learners will separate a mixture of FD&C dyes (colors certified and allowed by the US for the Food, Pharmaceutical, Cosmetics & Personal Care industry) to practice chromatography, a separation technique for mixtures. Learners will record their observations on a data table and note trends. This resource includes questions for learners and instructions for preparing the colors from M&Ms, Orange Kool-Aid, and food coloring.

House, The S.

2014-01-28

108

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

NASA Astrophysics Data System (ADS)

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 of the presence of preferential flow paths which have been found to strongly control the highest values of the average velocity at the source and affect the resulting longitudinal dispersion coefficient. This study showed additional lights on the impact of connectivity on transport and its role to obtain effective measurements of macrodispersion throughout the aquifer under RC transport. Reference: Fernàndez-Garcia D. et al. (2002) Convergent-flow tracer tests in heterogeneous media. Journal of Contaminant Hydrology 57 129-145. Fischer H. B. (1966) Longitudinal Dispersion in Laboratory and Natural Streams. Technical Rep. KH-R-12, California Institute of Technology, Pasadena, California. Gaspar E. (1987) Modern Trends in Tracer Hydrology, Volume II. CRC Press, Inc., Boca Raton, FL, USA.

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

2014-05-01

109

Osteoblastic cell proliferation with uniform distribution in a large scaffold using radial-flow bioreactor.  

PubMed

Bioreactors employing different types of in vitro physiological cell stimulation have been developed to obtain three-dimensional cultivation for tissue engineering. The aim of this study was to determine whether osteoblastic cells proliferated uniformly over a large scaffold with a diameter of 18 mm and height of 10 mm under dynamic cultivation with the radial-flow bioreactor (RFB), and thereby ascertain the potential of this system in the regeneration of jaw bone. Mouse osteoblastic cells (MC3T3-E1) were seeded onto type 1 collagen sheets. Cells were then incubated outside the reactor for 6 h to produce precultured sheets. The six precultured sheets were then placed in the RFB to fabricate the scaffolds. Cells were dynamically cultured for 1 week at 37°C, pH 7.4, dissolved oxygen 6.86 ppm, and with the culture medium circulating at 3 mL/min. As a control, static cultivation cultured in the same manner without the circulating culture medium and single cultivation in a culture dish were performed. The resulting cell proliferation and cell distribution were analyzed. After 1 week of dynamic cultivation, cells showed a fivefold and fourfold increase with uniform distribution throughout the three-dimensional scaffolds than those under the static and single cultivation as a control, respectively. These results indicate that the RFB is a promising system for three-dimensional cultivation of osteoblastic cells for treating large bone defects by tissue engineering. PMID:20367244

Arano, Taichi; Sato, Toru; Matsuzaka, Kenichi; Ikada, Yoshito; Yoshinari, Masao

2010-12-01

110

Hepatic reconstruction from fetal porcine liver cells using a radial flow bioreactor  

PubMed Central

AIM: To examine the efficacy of the radial flow bioreactor (RFB) as an extracorporeal bioartificial liver (BAL) and the reconstruction of liver organoids using embryonic pig liver cells. METHODS: We reconstructed the liver organoids using embryonic porcine liver cells in the RFB. We also determined the gestational time window for the optimum growth of embryonic porcine liver cells. Five weeks of gestation was designated as embryonic day (E) 35 and 8 wk of gestation was designated as E56. These cells were cultured for one week before morphological and functional examinations. Moreover, the efficacy of pulsed administration of a high concentration hepatocyte growth factor (HGF) was examined. RESULTS: Both cell growth and function were excellent after harvesting on E35. The pulsed administration of a high concentration of HGF promoted the differentiation and maturation of these fetal hepatic cells. Microscopic examination of organoids in the RFB revealed palisading and showed that bile duct-like structures were well developed, indicating that the organoids were mini livers. Transmission electron microscopy revealed microvilli on the luminal surfaces of bile duct-like structures and junctional complexes, which form the basis of the cytoskeleton of epithelial tissues. Furthermore, strong expression of connexin (Cx) 32, which is the main protein of hepatocyte gap junctions, was observed. With respect to liver function, ammonia detoxification and urea synthesis were shown to be performed effectively. CONCLUSION: Our system can potentially be applied in the fields of BAL and transplantation medicine. PMID:18461659

Ishii, Yuji; Saito, Ryota; Marushima, Hideki; Ito, Ryusuke; Sakamoto, Taro; Yanaga, Katsuhiko

2008-01-01

111

The galactic habitable zone of the Milky Way and M31 from chemical evolution models with gas radial flows  

NASA Astrophysics Data System (ADS)

The galactic habitable zone is defined as the region with sufficient abundance of heavy elements to form planetary systems in which Earth-like planets could be born and might be capable of sustaining life, after surviving to close supernova explosion events. Galactic chemical evolution models can be useful for studying the galactic habitable zones in different systems. We apply detailed chemical evolution models including radial gas flows to study the galactic habitable zones in our Galaxy and M31. We compare the results to the relative galactic habitable zones found with `classical' (independent ring) models, where no gas inflows were included. For both the Milky Way and Andromeda, the main effect of the gas radial inflows is to enhance the number of stars hosting a habitable planet with respect to the `classical' model results, in the region of maximum probability for this occurrence, relative to the classical model results. These results are obtained by taking into account the supernova destruction processes. In particular, we find that in the Milky Way the maximum number of stars hosting habitable planets is at 8 kpc from the Galactic Centre, and the model with radial flows predicts a number which is 38 per cent larger than what was predicted by the classical model. For Andromeda we find that the maximum number of stars with habitable planets is at 16 kpc from the centre and that in the case of radial flows this number is larger by 10 per cent relative to the stars predicted by the classical model.

Spitoni, E.; Matteucci, F.; Sozzetti, A.

2014-05-01

112

A viscous flow study of shock-boundary layer interaction, radial transport, and wake development in a transonic compressor  

NASA Technical Reports Server (NTRS)

A numerical study based on the 3D Reynolds-averaged Navier-Stokes equation has been conducted to investigate the detailed flow physics inside a transonic compressor. 3D shock structure, shock-boundary layer interaction, flow separation, radial mixing, and wake development are all investigated at design and off-design conditions. Experimental data based on laser anemometer measurements are used to assess the overall quality of the numerical solution. An additional experimental study to investigate end-wall flow with a hot-film was conducted, and these results are compared with the numerical results. Detailed comparison with experimental data indicates that the overall features of the 3D shock structure, the shock-boundary layer interaction, and the wake development are all calculated very well in the numerical solution. The numerical results are further analyzed to examine the radial mixing phenomena in the transonic compressor. A thin sheet of particles is injected in the numerical solution upstream of the compressor. The movement of particles is traced with a 3D plotting package. This numerical survey of tracer concentration reveals the fundamental mechanisms of radial transport in this transonic compressor.

Hah, Chunill; Reid, Lonnie

1991-01-01

113

The galactic habitable zone of the Milky Way and M31 from chemical evolution models with gas radial flows  

E-print Network

The galactic habitable zone is defined as the region with sufficient abundance of heavy elements to form planetary systems in which Earth-like planets could be born and might be capable of sustaining life, after surviving to close supernova explosion events. Galactic chemical evolution models can be useful for studying the galactic habitable zones in different systems. We apply detailed chemical evolution models including radial gas flows to study the galactic habitable zones in our Galaxy and M31. We compare the results to the relative galactic habitable zones found with "classical" (independent ring) models, where no gas inflows were included. For both the Milky Way and Andromeda, the main effect of the gas radial inflows is to enhance the number of stars hosting a habitable planet with respect to the "classical" model results, in the region of maximum probability for this occurrence, relative to the classical model results. These results are obtained by taking into account the supernova destruction process...

Spitoni, E; Sozzetti, A

2014-01-01

114

A Laplace transform solution for tracer tests in a radially convergent flow field with upstream dispersion  

Microsoft Academic Search

When tracers are introduced into an injection borehole, noticeable concentration gradients at the injection well may cause a backward spreading of the initial plume during radially convergent tracer tests. Based on this concept a non-rigorous mathematical model is developed to estimate the effect of backward spreading. The injection well with an instantaneous slug input is treated as a mathematical source

Jui-Sheng Chen; Chen-Wuing Liu; Chia-Shyun Chen; Hun-Der Yen

1996-01-01

115

Abstract--In this paper, Reversed-Flow Gas Chromatography (RF-GC) is utilized to investigate the  

E-print Network

Abstract--In this paper, Reversed-Flow Gas Chromatography (RF-GC) is utilized to investigate Chromatography (RF-GC) method can be used as an indicator to `measure' the evaporation rates of liquid Manuscript by a factor of 46-50% [16-22]. This paper demonstrates the utilization of RF-GC in the study of evaporation

Paris-Sud XI, Université de

116

Ion chromatography as a measurement device in continuous flow analysis of ice cores  

NASA Astrophysics Data System (ADS)

Melter-based continuous chemical analysis of ice cores has been increasingly employed in ice core research for fast, high resolution measurements of the chemical impurities in snow and ice. In continuous flow analysis (CFA), a heated melter generates uncontaminated flowing streams of ice core meltwater which are channeled directly into measurement devices, such as spectrophotometers, mass spectrometers and flow injection analyzers. These devices essentially serve as on-line and quantitative detectors for the melter-generated flow streams. Ion chromatography (IC) has been the preferred analytical technique for the determination of major chemical impurities in ice cores. Using IC as the measurement or detection technique for continuous flow melter analysis would provide an analytical system for measurement of all major chemical impurities in ice cores. We have constructed such a system by interfacing an ice core melter with several ion chromatographs. This technique (CFA-IC) takes advantage of the fast sample preparation and sub-sampling speed provided by a melter and the all-ion capability with low detection limits of ion chromatography. Initial testing and ice core analysis demonstrate that the CFA-IC technique is capable of (1) measuring all major ions, (2) high analysis speed as a result of reduced sample preparation time, and (3) high temporal resolution while requiring less ice than the conventional discrete sampling method.

Budner, D. M.; Cole-Dai, J.; Ferris, D.

2005-12-01

117

Performance evaluation of radial\\/vertical flow clarification applied to recirculating aquaculture systems  

Microsoft Academic Search

A prototype radial\\/vertical clarifier with 60° cone bottom was built and evaluated for application in recirculating aquaculture. Samples were analyzed for particle size distribution using a laser diffraction particle analyzer (Mastersizer S, Malvern Instruments Ltd., Worcestershire, UK) and total suspended solids (TSS) to determine the effectiveness of the clarifier. Surface area calculated mean influent and effluent particle diameters were 81.12±1.57?m

William Johnson; Shulin Chen

2006-01-01

118

Cylindrically confined pair-ion-electron and pair-ion plasmas having axial sheared flow and radial gradients  

SciTech Connect

The linear and nonlinear dynamics of pair-ion (PI) and pair-ion-electron plasmas (PIE) have been investigated in a cylindrical geometry with a sheared plasma flow along the axial direction having radial dependence. The coupled linear dispersion relation of low frequency electrostatic waves has been presented taking into account the Guassian profile of density and linear gradient of sheared flow. It is pointed out that the quasi-neutral cold inhomogeneous pure pair ion plasma supports only the obliquely propagating convective cell mode. The linear dispersion relation of this mode has been solved using boundary conditions. The nonlinear structures in the form of vortices formed by different waves have been discussed in PI and PIE plasmas.

Batool, Nazia; Saleem, H. [National Centre for Physics (NCP), Quaid-i-Azam University Campus, Islamabad (Pakistan)] [National Centre for Physics (NCP), Quaid-i-Azam University Campus, Islamabad (Pakistan)

2013-10-15

119

Indication of transverse radial flow in high-multiplicity proton-proton collisions at the Large Hadron Collider  

E-print Network

We analyze the measured spectra of $\\pi^\\pm$, $K^\\pm$, $p$($\\bar p$) in $pp$ collisions at $\\sqrt {s}$ = 0.9, 2.76 and 7 TeV, in the light of blast-wave model to extract the transverse radial flow velocity and kinetic temperature at freeze-out for the system formed in $pp$ collisions. The dependency of the blast-wave parameters on average charged particle multiplicity of event sample or the `centrality' of collisions has been studied and compared with results of similar analysis in nucleus-nucleus ($AA$) and proton-nucleus ($pA$) collisions. We analyze the spectra of $K_{s}^0$, $\\Lambda$($\\bar \\Lambda$) and $\\Xi^-$ also to see the dependence of blast-wave description on the species of produced particles. Within the framework of the blast-wave model, the study reveals indication of collective behavior for high-multiplicity events in $pp$ collisions at LHC. Strong transverse radial flow in high multiplicity $pp$ collisions and its comparison with that in $pA$ and $AA$ collisions match with predictions from a very recent theoretical work [Shuryak and Zahed 2013 arXiv:1301.4470] that addresses the conditions for applicability of hydrodynamics in $pp$ and $pA$ collisions.

Premomoy Ghosh; Sanjib Muhuri; Jajati k. Nayak; Raghava Varma

2014-02-27

120

3D flow in the axial-radial exhaust hood of a steam turbine  

NASA Astrophysics Data System (ADS)

The computation model of the 3D viscous flow is used for the analysis of the flow conditions in the model of steam turbine exhaust hood, that was in previous time investigated experimentally. The computation method and the obtained results are described. The calculation is concentrated on the finding of the influence of inlet velocity field and on the influence of compressibility of the flow medium. Especially it followed the fluid motion in the outlet vortex and the occurrence of the areas with flow separation.

Š?astný, M.; Škoda; Kolá?, P.; Tu?ek, A.

1997-12-01

121

3D flow in the axial-radial exhaust hood of a steam turbine  

Microsoft Academic Search

The computation model of the 3D viscous flow is used for the analysis of the flow conditions in the model of steam turbine exhaust hood, that was in previous time investigated experimentally. The computation method and the obtained results are described. The calculation is concentrated on the finding of the influence of inlet velocity field and on the influence of

M. Stastný; Skoda; P. Kolár; A. Tucek

1997-01-01

122

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

123

3D flow in the axial-radial exhaust hood of a steam turbine  

Microsoft Academic Search

The computation model of the 3D viscous flow is used for the analysis of the flow conditions in the model of steam turbine\\u000a exhaust hood, that was in previous time investigated experimentally. The computation method and the obtained results are described.\\u000a The calculation is concentrated on the finding of the influence of inlet velocity field and on the influence of

M. Š?astný; Škoda; P. Kolá?; A. Tu?ek

1997-01-01

124

Investigation of the flow in a radial compressor and its excitation effect of blade vibration  

SciTech Connect

In the design of modern centrifugal compressors stress and vibration problems are of increasing importance. Results of research work in this field is presented about stress calculations due to centrifugal force and an evaluation of the lift forces by means of flow data. Flow measurements were discussed investigating the excitation effect to the blades. Vibration measurements telemetered from 8 blades were carried out on the compressor with vaneless and vaned diffuser. Vibration of the whole impeller is the subject of a FE-calculation.

Haupt, U.; Rautenberg, M.

1984-08-01

125

Cosorption effect in gas chromatography: flow fluctuations caused by adsorbing carrier gases.  

PubMed

Adsorbing carrier gases have a number of advantages in analytical and preparative gas chromatography, such as clearer detector signals and higher column efficiencies. This work shows that adsorbing carrier gases also may be useful because they cause the mobile phase flow rate to become unsteady after injecting a small amount of sample. This work shows that a 100 microL sample of helium can liberate enough carbon dioxide carrier gas from a zeolite 5A packed column at 373 K, that the departure from the steady-state flow rate had an upper lobe area of 586 microL of carrier gas. This was confirmed by coupling a modified Langmuir kinetic model with the Ergun equation. PMID:15700469

Matuszak, Daniel; Gaddy, Glen D; Aranovich, Gregory L; Donohue, Marc D

2005-01-21

126

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

SciTech Connect

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.

Chertkov, Michael [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory; Backhaus, Scott [Los Alamos National Laboratory; Sule, Petr [NEW MEXICO CONSORTIUM

2009-01-01

127

Rapid simultaneous quantification of immunosuppressants in transplant patients by turbulent flow chromatography combined with tandem mass spectrometry  

Microsoft Academic Search

Background: Immunosuppressant therapeutic drug monitoring (TDM) is an important requirement in the management of post-transplant patients. Our aim was to develop and evaluate a robust high-throughput method using turbulent flow chromatography (TFC) coupled with liquid chromatography–tandem mass spectrometry (LC–MS\\/MS) for the simultaneous quantification of cyclosporin A (CsA), tacrolimus (FK 506) and sirolimus. Methods: A total of 1483 EDTA-blood pre-dosage samples

Uta Ceglarek; Jan Lembcke; Georg Martin Fiedler; Maria Werner; Helmut Witzigmann; Johann Peter Hauss; Joachim Thiery

2004-01-01

128

Radial mixing in turbomachines  

Microsoft Academic Search

A method for computing the effects of radial mixing in a turbomachinery blade row has been developed. The method fits in the framework of a quasi-3D flow computation and hence is applied in a corrective fashion to through flow distributions. The method takes into account both secondary flows and turbulent diffusion as possible sources of mixing. Secondary flow velocities determine

P. Segaert; Ch. Hirsch; J. Deruyck

1991-01-01

129

Computerized optimization of flows and temperature gradient in flow modulated comprehensive two-dimensional gas chromatography.  

PubMed

Informational entropy and syentropy percent were used to optimize the flows in the first (1D) and in the second (2D) dimension ((1)Fm and (2)Fm, respectively) as well as the temperature program rate (r) for the flow modulated GC×GC-FID separation of C6-C12 aromatic hydrocarbons in a low boiling petrochemical sample. The separations were performed on a column series consisting of a 25m×0.25mm i.d.×0.2?m df of the polar ionic liquid SLB-IL 100 (1,9-di(3-vinylimidazolium)nonane bis(trifluoromethylsulfonyl)imide) in the first dimension and 5m×0.25mm i.d.×0.25?m df apolar HP-5MS (5% phenyl-95% methylpolysiloxane) in the second dimension. A dependence of a distribution of individual aromatic hydrocarbons in the 2D retention plane on the carrier gas flows ((1)Fm, and (2)Fm,) and temperature gradient (r) was examined in this study. It was found that informational entropy and synentropy percent are advantageous criteria to characterize the distribution of peaks in the 2D retention plane. Maximum informational entropy and synentropy percents correspond to the maximum distribution of C6-C12 aromatic hydrocarbons in the corresponding 2D retention plane gained by the given separation using optimized values of individual carrier gas column volume flows and the temperature rate at the temperature programmed GC×GC separations. PMID:24861782

Májek, Pavel; Krup?ík, Ján; Gorovenko, Roman; Špánik, Ivan; Sandra, Pat; Armstrong, Daniel W

2014-07-01

130

A new split-flow injector for preparative liquid chromatography columns. Annular injection system.  

PubMed

The packing of large-diameter columns for liquid chromatography is still difficult and numerous publications have reported results from tests which prove the packing is heterogeneous. The slurry is more compact in the wall region and this reduces the flow of the mobile phase, leading to distortion of the sample zone in the column and generation of peak tailing. A new type of injection system for the head of the column has been developed which divides the flow of the solvent from the pump into two parts. One, without sample, is directed to a crown injector, close to the wall. By adjusting the ratio of this flow to that of the bulk flow it is possible to increase the speed of the mobile phase in this part of the stationary phase and reduce distortion of the sample zone. The other part of the solvent carries the sample to the stationary phase through a distributor. The results demonstrate the benefits of this annular injection system, which include increased efficiency and improved column stability. PMID:12012194

Dardoize, F; Clodic, G; Chevalet, J

2002-04-01

131

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

PubMed Central

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

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

2014-01-01

132

A simple chemical evolution model for the Milky Way disc with radial gas flows and stellar migration  

E-print Network

We introduce a simple treatment of stellar migration in a detailed chemical evolution model for the thin disc of the Milky Way that already includes gas radial flows and reproduces several observational constraints for the solar vicinity, as well as the whole disc. We find that stellar migration has a negligible effect on the G-dwarf metallicity distribution in the solar neighbourhood, even in presence of a significant drift from the innermost regions. Therefore we conclude that the G-dwarf metallicity distribution hardly gives any information to be used to quantify the extent of migration. On the other hand, a large fraction of the spread observed in the age-metallicity relation of solar neighbourhood stars can be explained by the presence of stars that originated at different Galactocentric distances, though part of the observed spread could still be due to errors in the determination of stellar ages. Finally, we show that a substantial stellar migration can significantly affect the observed distribution of...

Spitoni, E; Matteucci, F; Ciotti, L

2014-01-01

133

THE COMPACTNESS OF FRONT TRACKING FOR CHROMATOGRAPHY ELECTROPHORESIS AND INCOMPRESSIBLE MULTIPHASE FLOW  

E-print Network

THE COMPACTNESS OF FRONT TRACKING FOR CHROMATOGRAPHY ELECTROPHORESIS AND INCOMPRESSIBLE MULTIPHASE. SUMMARY An analysis of the equations of chromatography from the point of view of hyperbolic conservation a subsequence converging to a weak solution of the chromatography equations, with no restriction on the size

134

Rapid Catalyst Screening by a Continuous-Flow Microreactor Interfaced with Ultra High Pressure Liquid Chromatography  

PubMed Central

A high-throughput screening system for homogeneous catalyst discovery has been developed by integrating a continuous-flow capillary-based microreactor with ultra-high pressure liquid chromatography (UHPLC) for fast online analysis. Reactions are conducted in distinct and stable zones in a flow stream that allows for time and temperature regulation. UHPLC detection at high temperature allows high throughput online determination of substrate, product, and byproduct concentrations. We evaluated the efficacies of a series of soluble acid catalysts for an intramolecular Friedel-Crafts addition into an acyliminium ion intermediate within one day and with minimal material investment. The effects of catalyst loading, reaction time, and reaction temperature were also screened. This system exhibited high reproducibility for high-throughput catalyst screening and allowed several acid catalysts for the reaction to be identified. Major side products from the reactions were determined through off-line mass spectrometric detection. Er(OTf)3, the catalyst that showed optimal efficiency in the screening, was shown to be effective at promoting the cyclization reaction on a preparative scale. PMID:20666502

Fang, Hui; Xiao, Qing; Wu, Fanghui; Floreancig, Paul E.; Weber, Stephen G.

2010-01-01

135

Column properties and flow profiles of a flat, wide column for high-pressure liquid chromatography  

SciTech Connect

The design and the construction of a pressurized, flat, wide column for high-performance liquid chromatography (HPLC) are described. This apparatus, which is derived from instruments that implement over-pressured thin layer chromatography, can carry out only uni-dimensional chromatographic separations. However, it is intended to be the first step in the development of more powerful instruments that will be able to carry out two-dimensional chromatographic separations, in which case, the first separation would be a space-based separation, LC{sup x}, taking place along one side of the bed and the second separation would be a time-based separation, LC{sup t}, as in classical HPLC but proceeding along the flat column, not along a tube. The apparatus described consists of a pressurization chamber made of a Plexiglas block and a column chamber made of stainless steel. These two chambers are separated by a thin Mylar membrane. The column chamber is a cavity which is filled with a thick layer (ca. 1 mm) of the stationary phase. Suitable solvent inlet and outlet ports are located on two opposite sides of the sorbent layer. The design allows the preparation of a homogenous sorbent layer suitable to be used as a chromatographic column, the achievement of effective seals of the stationary phase layer against the chamber edges, and the homogenous flow of the mobile phase along the chamber. The entire width of the sorbent layer area can be used to develop separations or elute samples. The reproducible performance of the apparatus is demonstrated by the chromatographic separations of different dyes. This instrument is essentially designed for testing detector arrays to be used in a two-dimensional LC{sup x} x LC{sup t} instrument. The further development of two-dimension separation chromatographs based on the apparatus described is sketched.

Mriziq, Khaled S [ORNL; Guiochon, Georges A [ORNL

2008-01-01

136

Radial-flow bioreactor enables uniform proliferation of human mesenchymal stem cells throughout a three-dimensional scaffold.  

PubMed

Mesenchymal stem cells (MSCs) obtained from human bone marrow are pluripotent and have been expanded and differentiated into several kinds of mesodermal tissue in vitro. To create bioartificial tissues and organs for implantation, it is necessary to induce proliferation in such cells. In this study, a radial-flow bioreactor (RFB) was used to induce three-dimensional (3D) expansion of human MSCs (hMSCs) on a large scaffold. The effect of this expansion on cellular characteristics was investigated. To produce precultured sheets, the hMSCs were first seeded onto type 1 collagen sheets and incubated for 12?h, after which they were placed in the RFB for fabrication of scaffolds. The culture medium was circulated at 3?mL/min, and the cells were dynamically cultured for 1 week at 37°C. As a control, static cultivation in a culture dish was also carried out. Cellular expansion and characteristics were analyzed. Alkaline phosphatase (ALP) activity in the hMSCs was also investigated after dynamic culture in an osteogenesis induction medium to explore their potential for osteogenic differentiation. At 1 week of dynamic cultivation, a >60% increase was observed in a number of cells together with a uniform distribution throughout the scaffolds compared with under static conditions; no change in hMSC markers was observed. The hMSCs retained the ability for osteogenic differentiation after culture in the RFB. The present results indicate that 3D dynamic culture in an RFB enables uniform expansion of hMSCs with no change in cellular characteristics, suggesting the usefulness of this technique in tissue engineering. PMID:22834782

Katayama, Aiko; Arano, Taichi; Sato, Toru; Ikada, Yoshito; Yoshinari, Masao

2013-02-01

137

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

PubMed Central

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

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

2010-01-01

138

Salvage of femoropedal bypass graft complicated by interval gangrene and vein graft blowout using a flow-through radial forearm fasciocutaneous free flap  

Microsoft Academic Search

We report the case of a 71-year-old man who had interval gangrene of his calf with subsequent vein graft blowout 3 months after undergoing a femoral–to–dorsalis pedis saphenous vein bypass grafting procedure. To provide wound coverage, restore vascular continuity, and preserve functional ambulation, a flow-through radial forearm fasciocutaneous free flap was interposed between cut ends of the bypass graft. Venous

Michael A. Gooden; Andrew T. Gentile; Christopher P. Demas; Scott S. Berman; Joseph L. Mills

1997-01-01

139

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

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

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

2013-01-01

140

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

PubMed

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

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

2014-07-25

141

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

PubMed Central

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

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

2011-01-01

142

AIP/123-QED Instability of the vertical annular flow with a radial heating and rotating inner cylinder  

E-print Network

, UMR 6294 CNRS ­ Universit´e du Havre 53, rue de Prony ­ 76058 Le Havre Cedex, France (Dated: 20 annulus with a radial temperature gradient has been performed. Depending on values of control parameters number against the temperature gradient but not against any dimensionless control parameter

Paris-Sud XI, Université de

143

Chemical Evolution of the Galaxy : Radial Properties  

Microsoft Academic Search

The previous study of chemical evolution of the Galaxy is extended to the radial properties of the Galactic disk. The present model includes radial dependency of the time-dependent bimodal IMF, radial flow of material in the disk, and the change of type I supernova explosion rate with radial distance from the disk center as model parameters and observed gas and

Byeong-Gon Park; Yong Hee Kang; See-Woo Lee

1996-01-01

144

Radial engine  

SciTech Connect

A radial engine is described comprising: a housing; equally spaced openings disposed in ring-like arrangement on the periphery of the housing; a piston and cylinder arrangement in each of the opening, a piston rod for each arrangement fixed to and extending radially inwardly from its respective piston and through its respective opening; shoe means pivotally attached at the other end of each of the piston rod; radial guide means extending in the housing in line with each of the piston rods, and the shoe means provided with guide means followers to ensure radial reciprocal movement of the piston rods and shoe means; and a connecting ring journaled on a crankshaft for circular translation motion in the housing, the ring including a circular rim. Each shoe means includes an arcuate follower member being slidably connected to the rim of the connecting ring.

Kmicikiewicz, M.A.

1988-03-01

145

Generic serial and parallel on-line direct-injection using turbulent flow liquid chromatography/tandem mass spectrometry.  

PubMed

The development of turbulent flow chromatography (TFC) has enabled considerable growth in the utility of on-line direct-injection technologies. TFC has now become established in a large number of varied analytical environments, particularly drug discovery/pharmacokinetics, metabolite profiling, combinatorial library purification, pre-clinical and clinical GLP applications. The utility of turbulent flow technology for in-house pre-clinical and clinical quantitative applications has necessitated extensive valve-cleaning procedures, and consequently lengthy cycle-times, to effectively remove the system carry-over. In-house requirements for assay validation require carry-over less than 20% of the lowest level of quantification (LLOQ), corresponding to 0.02% carry-over for a linear calibration range incorporating 3 orders. A generic turbulent flow chromatography protocol has been developed for drug discovery that incorporates polymeric turbulent flow extraction (cyclone) with C18-based reverse-phase chromatography. Further, multiple wash steps are incorporated within the methodology to meet in-house requirements for carry-over. Selection of novel switching-valve materials based on polyarylethyl ketone (PAEK) and Hastelloy/Valcon E autosampler injection hardware has enabled us to significantly impact the cycle-time required to reduce carry-over. Consequently, optimal usage of switching valves has enabled parallel operation for a generic on-line direct-injection methodology to successfully reduce the total cycle-time. Overall reductions from 4 min per sample to 90 s per sample are shown with comparable data quality using a proprietary target molecule from 0.1-100 ng/mL. This paper describes the hardware configuration and methodologies utilized to perform generic serial and parallel on-line direct-injection using a Turboflow HTLC 2300 system. PMID:12207368

Grant, Russell P; Cameron, Cheryl; Mackenzie-McMurter, Shelley

2002-01-01

146

Simultaneous revascularization and coverage of a complex volar hand blast injury: case report using a contralateral radial forearm flow-through flap.  

PubMed

War wounds have created a unique reconstructive challenge for successful functional limb salvage. Various injury patterns related to improvised explosive devices (IEDs) occur and proper reconstruction goes a long way in reducing subsequent disfigurement and morbidity. One case in which a contralateral radial forearm flow-through flap is used for simultaneous revascularization and coverage of an IED hand blast injury is described. The advantages of this flap was its consistent arterial anatomy and long vascular pedicle. The thin skin paddle was used for soft tissue coverage of flexor tendon repair, median and ulnar nerve reconstruction, and metacarpal bone open reduction and internal fixation (ORIF). Recovery of motor function was satisfactory. PMID:18751601

Grewal, Navanjun S; Kumar, Anand R; Onsgard, Christina K; Taylor, Bruce J

2008-08-01

147

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)

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.

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

2014-08-01

148

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

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?L conical flow cell, could be optimized to ?0.007mAU at 2.5Hz, in SFC, which is very near the 0.006mAU manufacturer's specification for HPLC. The insulated version of this flow cell required far less optimization, compared to the un-insulated version. At 150bar, an experimental 3mm, 2?L flow cell, with only one side insulated, yielded noise slightly too high (?0.16-0.18mAU) for trace analysis, at 80Hz. However, at 200bar, noise at 80Hz was <0.06mAU, which should allow quantification of a 1mAU 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 performance. PMID:25189330

Berger, Terry A

2014-10-17

149

Development and industrial application of the 'all-over-controlled vortex distribution method' for designing radial and mixed flow impellers  

Microsoft Academic Search

A detailed experimental exploration is conducted for the 3D impeller-model stages and multistage compressors designed by the 'all-over-controlled' vortex-distribution method for centrifugal and mixed-flow compressors. Excellent performance is obtained. Since the blade generation is conducted simultaneously with the mean s(2) flow surface analysis, the design time for an impeller is fully controllable, ensuring the possibility of enlarging these 3D impellers'

S. J. Wang; M. J. Yuan; G. Xi; S. X. Liu; D. T. Qi; X. J. Chai

1992-01-01

150

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

SciTech Connect

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.

Narasimhan, T.N.; Zhu, Ming

1991-08-01

151

Radial lean direct injection burner  

DOEpatents

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.

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

2012-09-04

152

Development and industrial application of the 'all-over-controlled vortex distribution method' for designing radial and mixed flow impellers  

NASA Astrophysics Data System (ADS)

A detailed experimental exploration is conducted for the 3D impeller-model stages and multistage compressors designed by the 'all-over-controlled' vortex-distribution method for centrifugal and mixed-flow compressors. Excellent performance is obtained. Since the blade generation is conducted simultaneously with the mean s(2) flow surface analysis, the design time for an impeller is fully controllable, ensuring the possibility of enlarging these 3D impellers' range of application. The original method is presently improved in order to allow the design of small axial-length impellers.

Wang, S. J.; Yuan, M. J.; Xi, G.; Liu, S. X.; Qi, D. T.; Chai, X. J.

1992-06-01

153

Parallel segmented outlet flow high performance liquid chromatography with multiplexed detection.  

PubMed

We describe a new approach to multiplex detection for HPLC, exploiting parallel segmented outlet flow - a new column technology that provides pressure-regulated control of eluate flow through multiple outlet channels, which minimises the additional dead volume associated with conventional post-column flow splitting. Using three detectors: one UV-absorbance and two chemiluminescence systems (tris(2,2'-bipyridine)ruthenium(III) and permanganate), we examine the relative responses for six opium poppy (Papaver somniferum) alkaloids under conventional and multiplexed conditions, where approximately 30% of the eluate was distributed to each detector and the remaining solution directed to a collection vessel. The parallel segmented outlet flow mode of operation offers advantages in terms of solvent consumption, waste generation, total analysis time and solute band volume when applying multiple detectors to HPLC, but the manner in which each detection system is influenced by changes in solute concentration and solution flow rates must be carefully considered. PMID:24216209

Camenzuli, Michelle; Terry, Jessica M; Shalliker, R Andrew; Conlan, Xavier A; Barnett, Neil W; Francis, Paul S

2013-11-25

154

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

155

Determination of thermal conductivities of Sn-Zn lead-free solder alloys with radial heat flow and Bridgman-type apparatus  

NASA Astrophysics Data System (ADS)

The variations of thermal conductivities of solid phases versus temperature for pure Sn, pure Zn and Sn-9 wt.% Zn, Sn-14 wt.% Zn, Sn-50 wt.% Zn, Sn-80 wt.% Zn binary alloys were measured with a radial heat flow apparatus. The thermal conductivity ratios of liquid phase to solid phase for the pure Sn, pure Zn and eutectic Sn-9 wt.% Zn alloy at their melting temperature are found with a Bridgman-type directional solidification apparatus. Thus, the thermal conductivities of liquid phases for pure Sn, pure Zn and eutectic Sn-9 wt.% Zn binary alloy at their melting temperature were evaluated by using the values of solid phase thermal conductivities and the thermal conductivity ratios of liquid phase to solid phase.

Meydaneri, Fatma; Saatçi, Buket; Gündüz, Mehmet; Özdemir, Mehmet

2013-11-01

156

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...

157

Evaluation of longitudinal and transverse dispersivities/distance ratios for tracer test in a radially convergent flow field with scale-dependent dispersion  

NASA Astrophysics Data System (ADS)

This study presents a novel mathematical model for analysis of non-axisymmetrical solute transport in a radially convergent flow field with scale-dependent dispersion. A two-dimensional, scale-dependent advection-dispersion equation in cylindrical coordinates is derived based on assuming that the longitudinal and transverse dispersivities increase linearly with the distance of the solute transported from its injected source. The Laplace transform finite difference technique is applied to solve the two-dimensional, scale-dependent advection-dispersion equation with variable-dependent coefficients. Concentration contours for different times, breakthrough curves of average concentration over concentric circles with a fixed radial distance, and breakthrough curves of concentration at a fixed observation point obtained using the scale-dependent dispersivity model are compared with those from the constant dispersivity model. The salient features of scale-dependent dispersion are illustrated during the non-axisymmetrical transport from the injection well into extraction well in a convergent flow field. Numerical tests show that the scale-dependent dispersivity model predicts smaller spreading than the constant-dispersivity model near the source. The results also show that the constant dispersivity model can produce breakthrough curves of averaged concentration over concentric circles with the same shape as those from the proposed scale-dependent dispersivity model at observation point near the extraction well. Far from the extracting well, the two models predict concentration contours with significantly different shapes. The breakthrough curves at observation point near the injection well from constant dispersivity model always produce lesser overall transverse dispersion than those from scale-dependent dispersivity model. Erroneous dimensionless transverse/longitudinal dispersivity ratio may result from parametric techniques which assume a constant dispersivity if the dispersion process is characterized by a distance-dependent dispersivity relationship. A curve-fitting method with an example is proposed to evaluate longitudinal and transverse scale-proportional factors of a field with scale-dependent dispersion.

Chen, Jui-Sheng; Liu, Chen-Wuing; Liang, Ching-Ping

2006-06-01

158

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

SciTech Connect

A project has been initiated at Clemson Univ. to develop a HPLC/flow- cell system for analysis of non-gamma emitting radionuclides in environmental samples; an important component is development of a low background flow-cell detector that counts alpha and beta particles separately through pulse shape discrimination. Objective of the work presented here is to provide preliminary results of an evaluation of the following scintillators: CaF{sub 2}:Eu, scintillating glass, and BaF{sub 2}. Slightly acidic aqueous solutions of the alpha emitter {sup 233}U and the beta emitter {sup 45}Ca were used. Detection efficiencies and minimum detectable activities were determined.

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

1995-12-31

159

Radial Erosion  

NASA Technical Reports Server (NTRS)

[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.

2005-01-01

160

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

SciTech Connect

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 applied to the Euler head and another to the head loss to bring the predicted outlet pressure into better agreement with the experiment. These changes also brought the overall efficiency of the turbine into agreement with values cited by Barber Nichols for small turbines. More generally, the quality of measurement set data can in the future be improved by additional steps taken in the design and operation of the experimental apparatus. First, a thermocouple mounted at the nozzle inlet would provide a better indication of temperature at this key point. Second, heat losses from the turbine should be measured directly. Allowing the impeller to free wheel at inlet conditions and measuring the temperature drop between inlet and outlet would provide a more accurate measure of heat loss. Finally, the enthalpy change during operation is more accurately obtained by measuring the torque on the stator using strain gauges rather than by measuring pressure and temperature at inlet and outlet to infer thermodynamic states.

Vilim, R. B. (Nuclear Engineering Division)

2012-07-31

161

Validity of Darcy’s law at low flow-rates in liquid chromatography  

Microsoft Academic Search

The applicability of Darcy’s law at extremely low flow velocities has been questioned in the scientific literature. It was investigated using a simple chromatographic system. Ethylene glycol (viscosity, 19.9 cP at 20°C) was pumped through 10 to 25 cm long chromatographic columns packed with small porous spherical particles (size, 5 to 10 ?m). The dependence of the linear velocity of

Tivadar Farkas; Guoming Zhong; Georges Guiochon

1999-01-01

162

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)

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.

Katsanis, T.; Mcnally, W. D.

1977-01-01

163

Direct liquid sample introduction for flow injection analysis and liquid chromatography with inductively coupled argon plasma spectrometric detection  

SciTech Connect

The coupling of flow injection analysis (FIA) or high-performance liquid chromatography (HPLC) techniques to inductively coupled plasma atomic emission spectrometry (ICP-AES) offers new and attractive approaches for the determination of elemental concentrations in a wide variety of sample matrices. One of the most attractive features that FIA offers is a rapid and precise means of automating sample introduction into an ICP for simultaneous, multielement analysis at the trace, minor, and major constituent level with minimal sample consumption. The utilization of the ICP as a detector for HPLC retains most of the advantages of FIA-ICP, while providing the analyst with a powerful and versatile means of compound separation. This added dimension becomes particularly important when metal speciation is of primary interest, rather than total metal content. To date, the coupling of FIA and HPLC to the ICP has only been accomplished using conventional cross-flow, concentric, or Babington-type pneumatic nebulizers. Limits of detection under these conditions have generally been observed to be poorer when compared to conventional continuous sample flow conditions. These limitations have been attributed to the large dead-volume and the sample losses associated with conventional nebulizers and band broadening of eluents from FIA transfer tubing or HPLC columns prior to entering the nebulizer unit. In an effort to resolve these difficulties, a microconcentric nebulizer has been developed which is inserted directly into the tip of a conventional sample introduction tube of an ICP torch. Preliminary data on the potential utility of direct liquid sample introduction into the ICP are presented. 12 references, 6 figures, 1 table.

Lawrence, K.E.; Rice, G.W.; Fassel, V.A.

1984-02-01

164

Three-dimensional high-density culture of HepG2 cells in a 5-ml radial-flow bioreactor for construction of artificial liver.  

PubMed

A three-dimensional high-density cell culture is essential for the construction of an artificial tissue. Many researchers have reported that three-dimensional cell culture enhances cell function. The use of a radial-flow bioreactor (RFB) has enabled the cultivation of cells at high density for constructing a three-dimensional tissue. In this study, we have developed a novel, small RFB, which has a bed volume of 5 ml and is equipped with a porous support as an immobilized scaffold; its performance was tested using the hepatoblastoma cell line, HepG2. Among the other supports tested here, hydroxyl apatite was selected from the viewpoint of its ability to support good cell growth at high density with uniform distribution in a bioreactor. The HepG2 cells grew well in the scaffold under a sufficient supply of nutrients by radial flow and were used to construct a three-dimensional tissue in the scaffold. The concentration of the cells cultivated in this 5-ml RFB reached 10(8) cells/ml and the glucose consumption rate was almost similar to that obtained when using a 30-ml RFB, which has already been reported previously. This high glucose consumption continued over 7 d after the growth phase. Furthermore, albumin production was maintained in the stable phase. Gene expression profiles of cells obtained from long-term cultures in the 5-ml RFB were analyzed. It was found that the expressions of genes encoding the cell cycle-related proteins, cyclins, and cell cycle division 2 (cdc2) were suppressed in the stable phase. In addition, the number of cells incorporating 5'-bromo-2'-deoxyuridine (BrdU) in the stable phase markedly decreased compared with that in the growth phase. These results indicated that the majority of cells in the stable phase remain in the G0/G1 phase. Furthermore, this implies that the three-dimensional tissue constructed in the 5-ml RFB showed the high function similar to a normal liver in the human body. Therefore, the 5-ml RFB was considered as a useful tool and a substitute method for animal experiments. PMID:16233783

Hongo, Tomokatsu; Kajikawa, Mariko; Ishida, Seiichi; Ozawa, Shogo; Ohno, Yasuo; Sawada, Jun-Ichi; Umezawa, Akira; Ishikawa, Yoichi; Kobayashi, Takeshi; Honda, Hiroyuki

2005-03-01

165

Application of a radial-flow bioreactor in the production of beta1,3-N-acetylglucosaminyltransferase-2 fused with GFPuv using stably transformed insect cell lines.  

PubMed

An RFB (radial-flow bioreactor) with a reactor volume of 5 ml was applied to produce human beta3GnT (beta1,3-N-acetylglucosaminyltransferase) using two stably transformed insect cell lines. When air was supplied to the RFB, cell growth stopped at 4 days of culture and beta3GnT was not detected. However, with a supply of pure oxygen, the cell concentration, assumed from glucose consumption, increased by 1.3x10(7) cells/ml. Insect cells attached to poly(vinyl alcohol) matrixes packed in the RFB and grew confluently; 5.6 m-units/ml beta3GnT was produced under the conditions of pure oxygen supply and addition of glucose and glutamine. This RFB was first applied in beta3GnT production using stably transformed insect cells. The amount of beta3GnT production in only a 5 ml-scale RFB was comparable with that of a 100 ml shaking flask culture. PMID:15636581

Kwon, Mi Sun; Kato, Tatsuya; Dojima, Takashi; Park, Enoch Y

2005-08-01

166

On the use of quadrupole mass spectrometric detection for flow modulated comprehensive two-dimensional gas chromatography.  

PubMed

Flow modulated comprehensive two-dimensional gas chromatography with simultaneous flame ionization detection (FM GC×GC-FID) and quadrupole mass spectrometric detection (FM GC×GC-qMSD) was applied to the analysis of a quantitative reference standard sample covering the C5-C14 hydrocarbon range and a kerosene sample. This study reports the influence of the data acquisition frequency (DAF) of the qMSD on the qualitative and quantitative data. The DAF was varied between 5.27 and 25.45Hz. In GC×GC-qMSD, the characterization of peaks is getting worse with decreasing qMSD frequencies which deteriorate the quality of the 2D contour plots of the separations. It is, however, demonstrated that the improved characterization of the peaks at high qMSD frequencies is combined with loss in sensitivity and in spectral quality. Dependences of a (2)D hydrocarbon peak area (?Ai of all corresponding (2)D peaks) on the DAFs show negative slopes which testify the conclusion that the sensitivity of GC×GC-qMSD determinations decreases with the increase of DAF. Consequently, the limits of detection (LOD) and quantification (LOQ) increase with the increase of DAF. Moreover, quality criteria on recorded spectral data also indicate that the lower the DAF is, the higher is the spectral quality. PMID:24461452

Gorovenko, Roman; Krup?ík, Ján; Špánik, Ivan; Bo?ková, Ingrid; Sandra, Pat; Armstrong, Daniel W

2014-02-21

167

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

USGS Publications Warehouse

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.

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

1999-01-01

168

Efficient separations of intact proteins using slip-flow with nano-liquid chromatography-mass spectrometry.  

PubMed

A capillary with a pulled tip, densely packed with silica particles of 0.47 ?m in diameter, is shown to provide higher peak capacity and sensitivity in the separation of intact proteins by reversed-phase liquid chromatography-mass spectrometry (LC-MS). For a C18 bonded phase, slip flow gave a 10-fold flow enhancement to allow for stable nanospray with a 4-cm column length. Model proteins were studied: ribonuclease A, trypsin inhibitor, and carbonic anhydrase, where the latter had impurities of superoxide dismutase and ubiquitin. The proteins were well separated at room temperature with negligible peak tailing. The peak capacity for ubiquitin was 195 for a 10-min gradient and 315 for a 40-min gradient based on Gaussian fitting of the entire peak, rather than extrapolating the full-width at half-maximum. Separation of a cell lysate with a 60 min gradient showed extremely high peak capacities of 750 and above for a peptide and relatively homogeneous proteins. Clean, low noise mass spectra for each model protein were obtained. The physical widths of the peaks were an order of magnitude narrower than those of conventional columns, giving increased sensitivity. All proteins except ubiquitin exhibited significant heterogeneity apparently due to multiple proteoforms, as indicated by both peak shapes and mass spectra. The chromatograms exhibited excellent reproducibility in retention time, with relative standard deviations of 0.09 to 0.34%. The results indicate that submicrometer particles are promising for improving the separation dimension of LC in top-down proteomics. PMID:24383398

Wu, Zhen; Wei, Bingchuan; Zhang, Ximo; Wirth, Mary J

2014-02-01

169

Radial head fracture - aftercare  

MedlinePLUS

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

170

Isolation of Imperatorin, Oxypeucedanin, and Isoimperatorin from Angelica dahurica (Fisch. ex Hoffm) Benth. et Hook by Stepwise Flow Rate High?Speed Countercurrent Chromatography  

Microsoft Academic Search

Stepwise flow rate preparative high?speed countercurrent chromatography (HSCCC) was successfully used for isolation and purification of imperatorin, oxypeucedanin, and isoimperatorin from a crude root extract of Angelica dahurica (Fisch. ex Hoffm) Benth. et Hook. The separation was performed with a two?phase solvent system composed of n?hexane?ethyl acetate?methanol?water at volume ratio of 5:5:4:6, v\\/v\\/v\\/v, which had been selected by analytical HSCCC.

Yun Wei; Yoichiro Ito

2006-01-01

171

Flow rate gradient high-speed counter-current chromatography separation of five diterpenoids from Triperygium wilfordii and scale-up  

Microsoft Academic Search

In this paper, high-speed counter-current chromatography (HSCCC) instruments with different gravitational forces were applied for the separation of bioactive compounds from Triperygium wilfordii Hook.f. The critical parameters including sample concentration, sample volume and flow rate were first optimized on an analytical Mini-DE HSCCC system, and then scaled up to a preparative TBE 300A HSCCC system. Although this scale-up process was

Aihua Peng; Rui Li; Jia Hu; Lijuan Chen; Xia Zhao; Houding Luo; Haoyu Ye; Yuan Yuan; Yuquan Wei

2008-01-01

172

Radial cold trap  

DOEpatents

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.

Grundy, B.R.

1981-09-29

173

Sorption of para-xylene vapors on salt-treated soils measured by flow-equilibration and gas chromatography methods  

SciTech Connect

The impact of soil properties other than organic C content and surface area on vapor-phase sorption has rarely been considered. This study was conducted to determine the effect of salt, namely CaCl{sub 2}, on the sorption of p-xylene vapor under anhydrous and hydrated conditions. Sorption on Webster soil (Typic Haploquolls) before and after removal of organic C was measured using a flow-equilibration method. in addition, the utility of an eluted pulse gas chromatography method was evaluated using the sand fraction of Oldsmar soil (Alfic Arenic Haplaquods) as a column-packing material. The CaCl{sub 2} significantly decreased p-xylene sorption at both 0 and 90% RH for both adsorbents. Under anhydrous conditions, reduced sorption by Oldsmar sand was evidenced at low p-xylene vapor pressures by a constant net retention volume and symmetrical peaks, indicating linear sorption and ideal behavior at these vapor pressures (i.e., the Henry`s region). In the absence of salt, the net retention volume continued to increase at p-xylene vapor pressures as low as 0.33 Pa, indicating isotherm nonlinearity, even at this low vapor pressure. This difference in retention behavior suggests that salt modified the nature of the surface of the sorbents. Under hydrated conditions, the reduction in sorption may be related to the salting-out effect of CaCl{sub 2} on gas solubility in adsorbed water films. These data suggest that the distribution and migration of organic vapors may be substantially greater in salt-affected soils due to reduced sorption on both the dry and water-coated solid phases that am present. 27 refs., 5 figs.

Rhue, R.D.; Pennell, K.D.; Reve, W.H. [Univ. of Florida, Gainesville, FL (United States)] [and others

1993-07-01

174

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)

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.

Katsanis, T.; Mcnally, W. D.

1977-01-01

175

On radial geodesic forcing of zonal modes  

SciTech Connect

The elementary local and global influence of geodesic field line curvature on radial dispersion of zonal modes in magnetised plasmas is analysed with a primitive drift wave turbulence model. A net radial geodesic forcing of zonal flows and geodesic acoustic modes can not be expected in any closed toroidal magnetic confinement configuration, since the flux surface average of geodesic curvature identically vanishes. Radial motion of poloidally elongated zonal jets may occur in the presence of geodesic acoustic mode activity. Phenomenologically a radial propagation of zonal modes shows some characteristics of a classical analogon to second sound in quantum condensates.

Kendl, A. [Institute for Ion Physics and Applied Physics, Association Euratom-OeAW, University of Innsbruck, A-6020 Innsbruck (Austria)

2011-07-15

176

Discharge Algorithms for Canal Radial Gates.  

National Technical Information Service (NTIS)

Discharge algorithms for canal radial gates that can be applied to manual and/or automatic flow regulation of prototype canals or to mathematical model simulation of canal systems were developed through an extensive research program. Existing methods do n...

C. P. Buyalski

1983-01-01

177

Applying Chromatography.  

ERIC Educational Resources Information Center

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)

Klein, Jessie W.; Patev, Paul

1998-01-01

178

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

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

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

2014-08-13

179

Determination of free cortisol and free cortisone in human urine by on-line turbulent flow chromatography coupled to fused-core chromatography-tandem mass spectrometry (TFC-HPLC-MS/MS).  

PubMed

Urinary free cortisol and urinary free cortisone are decisive markers for the diagnosis of syndromes related to the dysfunction of the adrenal gland or to evaluate certain enzymatic disorders. Here, we present a new method, designed for routine laboratory use, which enables quick determination of these analytes with minor sample workup. Turbulent flow chromatography shortens sample preparation, and connection to a fused-core particle-packed column (rugged amide-embedded C18 phase) permits a rapid and effective separation of the analytes, as well as additional separation from other related and isobaric compounds present in urine. Urinary isobaric compounds were successfully identified. The method requires only 100 ?l of urine supernatant per sample. The total time between injections is 9.5 min. The solvents used for both turbulent and analytical chromatography are water and methanol, and the relatively low flows needed during the method resulted in an extended life of the columns. Linearity showed a R (2)?>?0.994. Limit of detection and limit of quantification are 0.5 and 1.0 ng/ml for cortisone and 1.0 and 2.0 ng/ml for cortisol. Recoveries ranged from 99.7 to 109.1 % for cortisone and from 98.7 to 102.9 % for cortisol. Accuracy values (relative errors) for intra- and inter-assay experiments were always below 8 %, whereas precision (percent CV) ranged from 3.7 to 10.7 %. No matrix effects were detected during the validation process. The reproducibility for each analyte's retention time was excellent, with a coefficient of variation always below 0.2 %. The final validation step included the study of urine samples from healthy children and from children previously diagnosed with corticoidal disorders. The high selectivity achieved enables quick data handling. PMID:24287634

Sánchez-Guijo, Alberto; Hartmann, Michaela F; Shi, Lijie; Remer, Thomas; Wudy, Stefan A

2014-01-01

180

The effect of radial artery reconstruction on the radial forearm donor site: a prospective study  

Microsoft Academic Search

The purpose of this study was to evaluate the effect of radial artery reconstruction after radial forearm flap elevation and\\u000a to study whether a vein graft can stay patent in this position. Ten consecutive oral cancer patients were included in the\\u000a study. Pre-operative Allen's test was performed, and the flow velocity of both radial and ulnar arteries was recorded using

Salvatore Giordano; Fulvio Lorenzetti; Esa Muuronen; Erkki Suominen; Sinikka Suominen

2009-01-01

181

Impact of radial artery cannulation for coronary angiography and angioplasty on radial artery function.  

PubMed

The radial artery is commonly used as a conduit in coronary artery bypass grafting. No data exist on the effects of radial sheath insertion on radial artery function. Because many patients considered for coronary artery bypass grafting have had previous radial procedures, it is important to understand any effects radial sheath insertion may have on radial artery function. Twenty-two patients who underwent elective coronary angiography or angioplasty with a 6Fr sheath through the right radial artery were studied. Radial artery function was assessed using ultrasound to measure flow-mediated dilation (FMD). Reactive hyperemia was produced by 5-minute cuff inflation on the arm to suprasystolic pressures. Radial artery diameter was measured at rest and 1 minute after cuff deflation. FMD was expressed as percent change in radial diameter compared with at rest. In all cases, the left radial artery was studied as a control. Patients were studied before sheath insertion, immediately after sheath insertion, and 6 weeks after sheath insertion. The FMD of the cannulated arm was 13.2% before sheath insertion versus 3.6% immediately after sheath insertion (p <0.01) and 0.2% (p <0.01) 9 weeks after sheath insertion. In contrast, there were no significant changes in the noncannulated arm at either time point. In conclusion, radial artery sheath insertion for coronary angiography or angioplasty results in immediate and persistent blunting of FMD, suggesting severe vasomotor dysfunction. Radial artery sheath insertion has important effects on radial artery function that must be considered when selecting radial conduits for coronary artery bypass grafting. PMID:17293183

Burstein, Jason M; Gidrewicz, Dominica; Hutchison, Stuart J; Holmes, Kate; Jolly, Sanjit; Cantor, Warren J

2007-02-15

182

Improving Peak Capacity in Fast On-Line Comprehensive Two-Dimensional Liquid Chromatography with Post First Dimension Flow-Splitting  

PubMed Central

The use of flow splitters between the two dimensions in on-line comprehensive two dimensional liquid chromatography (LC×LC) has not received very much attention in comparison to their use in GC×GC where they are quite common. In principle, splitting the flow after the first dimension column and performing on-line LC×LC on this constant fraction of the first dimension effluent should allow the two dimensions to be optimized almost independently. When there is no flow splitting any change in the first dimension flow rate has an immediate impact on the second dimension. With a flow splitter one could for example double the flow rate into the first dimension column and do a 1:1 flow split without changing the sample loop size or the sampler’s collection time. Of course, the sensitivity would be diminished but this can be partially compensated by use of a larger injection; this will likely only amount to a small price to pay for this increased resolving power and system flexibility. Among other benefits, we found a 2-fold increase in the corrected 2D peak capacity and the number of observed peaks for a 15 min analysis time by using a post first dimension flow splitter. At a fixed analysis time this improvement results primarily from an increase in the gradient time resulting from the reduced system re-equilibration time and to a smaller extent it is due to the increased peak capacity achieved by full optimization of the first dimension. PMID:22017622

Filgueira, Marcelo R.; Huang, Yuan; Witt, Klaus; Castells, Cecilia; Carr, Peter W.

2011-01-01

183

On-line coupling of macroporous resin column chromatography with direct analysis in real time mass spectrometry utilizing a surface flowing mode sample holder.  

PubMed

A surface flowing mode sample holder was designed as an alternative sampling strategy for direct analysis in real time mass spectrometry (DART-MS). With the sample holder, the on-line coupling of macroporous resin column chromatography with DART-MS was explored and the new system was employed to monitor the column chromatography elution process of Panax notoginseng. The effluent from macroporous resin column was first diluted and mixed with a derivatization reagent on-line, and the mixture was then directly transferred into the ionization region of DART-MS by the sample holder. Notoginsenosides were methylated and ionized in a metastable helium gas stream, and was introduced into MS for detection. The on-line system showed reasonable repeatability with a relative standard deviation of 12.3% for the peak area. Three notoginsenosides, i.e. notoginsenoside R1, ginsenoside Rb1 and ginsenoside Rg1, were simultaneously determined during the eluting process. The alteration of the chemical composition in the effluent was accurately identified in 9 min, agreeing well with the off-line analysis. The presented technique is more convenient compared to the traditional UPLC method. These results suggest that the surface flowing mode DART-MS has a good potential for the on-line process monitoring in the pharmaceutical industry. PMID:24456593

Zeng, Shanshan; Wang, Lu; Chen, Teng; Qu, Haibin

2014-02-01

184

Novel Integration Radial and Axial Magnetic Bearing  

NASA Technical Reports Server (NTRS)

Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.

Blumenstock, Kenneth; Brown, Gary

2000-01-01

185

Novel Integrated Radial and Axial Magnetic Bearing  

NASA Technical Reports Server (NTRS)

Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics, separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and analysis results will be presented.

Blumenstock, Kenneth A.; Brown, Gary L.; Powers, Edward I. (Technical Monitor)

2000-01-01

186

Chromatography Theory  

NSDL National Science Digital Library

James Hardy has produced a number of presentation-style lecture modules for analytical chemistry. This is a very good module that covers the introductory theory of chromatography. The material includes information on chromatography along with plate and kinetic theories. It is a colorful and well planned presentation of the introduction to chromatography that could be used as the basis for lectures on chromatography at the introductory analytical chemistry or instrumental analysis level.

2011-04-13

187

Affinity Chromatography  

NSDL National Science Digital Library

This is an experiment showing the application of affinity chromatography to the separation of albumin from horse serum. A brief introduction of affinity chromatography and how it is being used in this specific experiment is given. This appears to be a good experiment to show the advantages of affinity chromatography in separating specific proteins from a complex matrix and would be useful in a biochemistry course or a course that is specifically looking at differing types of chromatography.

Diresta, Dan

2011-05-23

188

Radial arm strike rail  

DOEpatents

The radial arm strike rail assembly is a system for measurement of bearings, directions, and stereophotography for geologic mapping, particularly where magnetic compasses are not appropriate. The radial arm, pivoting around a shaft axis, provides a reference direction determination for geologic mapping and bearing or direction determination. The centerable and levelable pedestal provide a base for the radial arm strike rail and the telescoping camera pedestal. The telescoping feature of the radial arm strike rail allows positioning the end of the rail for strike direction or bearing measurement with a goniometer.

McKeown, Mark H. (Golden, CO); Beason, Steven C. (Lakewood, CO)

1991-01-01

189

Plastic Models Designed to Produce Large Height-to-Length Ratio Steady-State Planar and Axisymmetric (Radial) Viscous Liquid Laminar Flow Gravity Currents  

ERIC Educational Resources Information Center

Naturally occurring gravity currents include events such as air flowing through an open front door, a volcanic eruption's pyroclastic flow down a mountainside, and the spread of the Bhopal disaster's methyl isocyanate gas. Gravity currents typically have a small height-to-distance ratio. Plastic models were designed and constructed with a…

Blanck, Harvey F.

2012-01-01

190

The development and validation of a turbulent flow chromatography-tandem mass spectrometry method for the endogenous steroid profiling of equine serum.  

PubMed

A method for the detection and quantitation of 35 endogenous steroids in equine serum was developed and validated. Androgens, estrogens, progestins and their metabolites potentially present in serum were simultaneously monitored in one method using on-line sample extraction by turbulent flow chromatography (TFC) on a 2-dimensional liquid chromatography system and detected on a triple-stage quadrupole mass spectrometer by electrospray ionization. Analytes were detected and quantitated by single-reaction monitoring or selected-ion monitoring. Limits of detection (range 0.025-10 ng mL(-1)) and quantitation (range 0.125-25 ng mL(-1)) along with recovery and matrix effects were determined for each analyte. Inter- and intra-day accuracy and precision was assessed for with the majority of analytes having %CV less than 20% and accuracy within 20% of the expected concentrations. Eight of the 35 analytes were unable to meet these guidelines across all of the quality control concentrations monitored for each analyte. This method was used to determine the endogenous steroid profiles of Thoroughbred horses and has been modified for use in non-human primates and cell culture. PMID:22902915

Moeller, Benjamin C; Stanley, Scott D

2012-09-15

191

Triple acting radial seal  

DOEpatents

A triple acting radial seal used as an interstage seal assembly in a gas turbine engine, where the seal assembly includes an interstage seal support extending from a stationary inner shroud of a vane ring, the interstage seal support includes a larger annular radial inward facing groove in which an outer annular floating seal assembly is secured for radial displacement, and the outer annular floating seal assembly includes a smaller annular radial inward facing groove in which an inner annular floating seal assembly is secured also for radial displacement. A compliant seal is secured to the inner annular floating seal assembly. The outer annular floating seal assembly encapsulates the inner annular floating seal assembly which is made from a very low alpha material in order to reduce thermal stress.

Ebert, Todd A (West Palm Beach, FL); Carella, John A (Jupiter, FL)

2012-03-13

192

Methods and apparatus for radially compliant component mounting  

DOEpatents

Methods and apparatus for a mounting assembly for a liner of a gas turbine engine combustor are provided. The combustor includes a combustor liner and a radially outer annular flow sleeve. The mounting assembly includes an inner ring surrounding a radially outer surface of the liner and including a plurality of axially extending fingers. The mounting assembly also includes a radially outer ring coupled to the inner ring through a plurality of spacers that extend radially from a radially outer surface of the inner ring to the outer ring.

Bulman, David Edward (Cincinnati, OH); Darkins, Jr., Toby George (Loveland, OH); Stumpf, James Anthony (Columbus, IN); Schroder, Mark S. (Greenville, SC); Lipinski, John Joseph (Simpsonville, SC)

2012-03-27

193

CHROMATOGRAPHY A ELSEVIER Journal of Chromatography A, 662 (1994) 369-373  

E-print Network

JOURNAL OF CHROMATOGRAPHY A ELSEVIER Journal of Chromatography A, 662 (1994) 369-373 Determination and electroosmotic flow of polytetrafluoroethylene (PTFE) capil- laries was measured. A number of papers have been

Miksik, Ivan

194

Development and performance evaluation of an ultralow flow nanoliquid chromatography-tandem mass spectrometry set-up.  

PubMed

LC-MS/MS is the most commonly used technique for the identification and characterization of proteins. The efficiency of the electrospray process is a critical factor in LC-MS/MS. Despite the benefits associated with very low flow rates for the ionization efficiency, most LC-MS/MS platforms are operated at relatively high flow rates. The purpose of this work was to develop a nano LC system operable at a flow rate of 20 nL/min, applicable for routine analysis in proteomics laboratories. Peptide separation was performed with an analytical column packed with 2 ?m porous chromatographic beads, a length of 25 cm and an inner diameter (i.d.) of 25 ?m. Practical usability, reproducibility, and overall performance of the system were evaluated with a tryptic peptide mixture generated from HeLa cells. Using 100 ng of sample, we identified on average 3721 protein groups based on 25,699 peptides. We demonstrate that the number of peptides identified with this system increases with decreasing flow rates. Probing the sensitivity of the set-up we analyzed only 10 ng of the sample, identifying an average number of 2042 protein groups based on 11 424 peptides. All MS data have been deposited in the ProteomeXchange with identifier PXD000396 (http://proteomecentral.proteomexchange.org/dataset/PXD000396). PMID:24920484

Köcher, Thomas; Pichler, Peter; De Pra, Mauro; Rieux, Laurent; Swart, Remco; Mechtler, Karl

2014-09-01

195

Chromatography Theory  

NSDL National Science Digital Library

This site contains standard definitions related to chromatography similar to treatments found in analytical chemistry textbooks. It introduces the beginning student to Liquid Chromatography concepts relevant to biochemistry and includes a good example of choosing a mobile phase pH for a protein separation based on ion exchange.

2011-05-26

196

Column Chromatography  

NSDL National Science Digital Library

In this activity, learners separate the components of Gatorade using a home-made affinity column. In doing so, learners model the basic principle of affinity chromatography, a technique used to purify chemicals as well as bio-pharmaceuticals and petroleum products. This resource contains information about affinity chromatography and polarity.

Yu, Julie

2007-01-01

197

Affinity Chromatography GST-tagged Proteins  

E-print Network

Affinity Chromatography GST-tagged Proteins His-tagged Proteins Antibody Immobilization Nucleotide binding Proteins Phospho-Aminoacid binding Proteins www.jenabioscience.com #12;Table of Contents AffinityChromatography Affinity Chromatography 3 GST-tagged Proteins 4 Glutathione ChroMatrixTM, Fast Flow 4 GST Cleavage Capture

Lebendiker, Mario

198

Screened hydrogenic radial integrals  

NASA Technical Reports Server (NTRS)

The screened hydrogenic radial integral for discrete-discrete and discrete-continuum transitions is expressed in forms suitable for obtaining closed-form expressions for specific transitions. Two effective-charge parameters, for the initial state and for the final state, are retained in these formulas. As examples, explicit expressions for a few transitions are derived, and a method for obtaining a series for a discrete-discrete radial integral, suitable for large final-state principal quantum numbers, is indicated.

Khandelwal, G. S.; Pritchard, W. M.; Grubb, G.; Khan, F.

1989-01-01

199

Understanding the mechanism of virus removal by Q sepharose fast flow chromatography during the purification of CHO-cell derived biotherapeutics.  

PubMed

During production of therapeutic monoclonal antibodies (mAbs) in mammalian cell culture, it is important to ensure that viral impurities and potential viral contaminants will be removed during downstream purification. Anion exchange chromatography provides a high degree of virus removal from mAb feedstocks, but the mechanism by which this is achieved has not been characterized. In this work, we have investigated the binding of three viruses to Q sepharose fast flow (QSFF) resin to determine the degree to which electrostatic interactions are responsible for viral clearance by this process. We first used a chromatofocusing technique to determine the isoelectric points of the viruses and established that they are negatively charged under standard QSFF conditions. We then determined that virus removal by this chromatography resin is strongly disrupted by the presence of high salt concentrations or by the absence of the positively charged Q ligand, indicating that binding of the virus to the resin is primarily due to electrostatic forces, and that any non-electrostatic interactions which may be present are not sufficient to provide virus removal. Finally, we determined the binding profile of a virus in a QSFF column after a viral clearance process. These data indicate that virus particles generally behave similarly to proteins, but they also illustrate the high degree of performance necessary to achieve several logs of virus reduction. Overall, this mechanistic understanding of an important viral clearance process provides the foundation for the development of science-based process validation strategies to ensure viral safety of biotechnology products. PMID:19575414

Strauss, Daniel M; Lute, Scott; Tebaykina, Zinaida; Frey, Douglas D; Ho, Cintia; Blank, Gregory S; Brorson, Kurt; Chen, Qi; Yang, Bin

2009-10-01

200

Periostin, discovered by nano-flow liquid chromatography and mass spectrometry, is a novel marker of diabetic retinopathy  

SciTech Connect

Research highlights: {yields} In proliferative membrane and epiretinal membrane specimens, the numbers of proteins are 225 and 154, respectively, and 123 proteins are common to both. {yields} Periostin and thrombospondin-1 proteins are unique to the proliferative membrane specimens. {yields} The expression of periostin is significantly up-regulated in proliferative membrane specimens. -- Abstract: Diabetes can lead to serious microvascular complications including proliferative diabetic retinopathy (PDR), the leading cause of blindness in adults. Recent studies using gene array technology have attempted to apply a hypothesis-generating approach to elucidate the pathogenesis of PDR, but these studies rely on mRNA differences, which may or may not be related to significant biological processes. To better understand the basic mechanisms of PDR and to identify potential new biomarkers, we performed shotgun liquid chromatography (LC)/tandem mass spectrometry (MS/MS) analysis on pooled protein extracts from neovascular membranes obtained from PDR specimens and compared the results with those from non-vascular epiretinal membrane (ERM) specimens. We detected 226 distinct proteins in neovascular membranes and 154 in ERM. Among these proteins, 102 were specific to neovascular membranes and 30 were specific to ERM. We identified a candidate marker, periostin, as well as several known PDR markers such as pigment epithelium-derived factor (PEDF). We then performed RT-PCR using these markers. The expression of periostin was significantly up-regulated in proliferative membrane specimens. Periostin induces cell attachment and spreading and plays a role in cell adhesion. Proteomic analysis by LC/MS/MS, which permits accurate quantitative comparison, was useful in identifying new candidates such as periostin potentially involved in the pathogenesis of PDR.

Takada, Michiya [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan)] [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan); Ban, Yoshiyuki, E-mail: yshyban@yahoo.co.jp [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan)] [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan); Yamamoto, Gou [Department of Oral Pathology and Diagnosis, School of Dentistry, Showa University, Tokyo (Japan)] [Department of Oral Pathology and Diagnosis, School of Dentistry, Showa University, Tokyo (Japan); Ueda, Toshihiko; Saito, Yuta; Nishimura, Eiichi; Fujisawa, Kunimi; Koide, Ryohei [Department of Ophthalmology, Showa University School of Medicine, Tokyo (Japan)] [Department of Ophthalmology, Showa University School of Medicine, Tokyo (Japan); Mizutani, Masakazu; Kozawa, Tadahiko; Shiraishi, Yuji [Kozawa Eye Hospital and Diabetes Center, Ibaraki-ken (Japan)] [Kozawa Eye Hospital and Diabetes Center, Ibaraki-ken (Japan); Bando, Yasuhiko [Biosys Technologies, Inc., Meguro, Tokyo (Japan)] [Biosys Technologies, Inc., Meguro, Tokyo (Japan); Tachikawa, Tetsuhiko [Department of Oral Pathology and Diagnosis, School of Dentistry, Showa University, Tokyo (Japan)] [Department of Oral Pathology and Diagnosis, School of Dentistry, Showa University, Tokyo (Japan); Hirano, Tsutomu [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan)] [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan)

2010-08-20

201

Chromatography 50 Chem 355 Jasperse Chromatography  

E-print Network

Chromatography 50 Chem 355 Jasperse Chromatography BACKGROUND Chromatography is a powerful. Advantages for chromatography are its power and generality (not limited to liquids or solids or the need. Chromatography Every type of chromatography depends on the distribution of a substance between two phases

Jasperse, Craig P.

202

AN OPTIMIZATION TECHNIQUE FOR RADIAL COMPRESSOR IMPELLERS  

Microsoft Academic Search

A software tool has been created to aid in automate d impeller design within an integrated design system for radial flow impellers. The design tool takes the results f rom the 1D preliminary design process and uses these to define a parameterized blade geometry, which incorporates features that are required for low mechanical stresses and s imple manufacturing. This geometry

Michael Casey; Frank Gersbach; Chris Robinson

2008-01-01

203

Analysing radial flow features in p-Pb and p-p collisions at several TeV by studying identified particle production in EPOS3  

E-print Network

Experimental transverse momentum spectra of identified particles in p-Pb collisions at 5.02 TeV show many similarities to the corresponding Pb-Pb results, the latter ones usually being interpreted in term of hydrodynamic flow. We analyse these data using EPOS3, an event generator based on a 3D+1 viscous hydrodynamical evolution starting from flux tube initial conditions, which are generated in the Gribov-Regge multiple scattering framework. An individual scattering is referred to as Pomeron, identified with a parton ladder, eventually showing up as flux tubes (or strings). Each parton ladder is composed of a pQCD hard process, plus initial and final state linear parton emission. Nonlinear effects are considered by using saturation scales $Q_{s}$, depending on the energy and the number of participants connected to the Pomeron in question. We compute transverse momentum ($p_{t}$) spectra of pions, kaons, protons, lambdas, and $\\Xi$ baryons in p-Pb and p-p scattering, compared to experimental data and many other models. In this way we show in a quantitative fashion that p-Pb data (and even p-p ones) show the typical ``flow effect'' of enhanced particle production at intermediate $p_{t}$ values, more and more visible with increasing hadron mass.

K. Werner; B. Guiot; Iu. Karpenko; T. Pierog

2013-12-04

204

Exclusion Chromatography  

NSDL National Science Digital Library

This site contains a brief description of the separation mechanism in size exclusion chromatography. The picture helps visualize the separation, but the site features a simplified and idealized presentation useful for students new to the concept.

Kimball, John W.

2011-05-03

205

Radial turbine cooling  

NASA Technical Reports Server (NTRS)

Radial turbines have been used extensively in many applications including small ground based electrical power generators, automotive engine turbochargers and aircraft auxiliary power units. In all of these applications the turbine inlet temperature is limited to a value commensurate with the material strength limitations and life requirements of uncooled metal rotors. To take advantage of all the benefits that higher temperatures offer, such as increased turbine specific power output or higher cycle thermal efficiency, requires improved high temperature materials and/or blade cooling. Extensive research is on-going to advance the material properties of high temperature superalloys as well as composite materials including ceramics. The use of ceramics with their high temperature potential and low cost is particularly appealing for radial turbines. However until these programs reach fruition the only way to make significant step increases beyond the present material temperature barriers is to cool the radial blading.

Roelke, Richard J.

1992-01-01

206

Theoretical evaluation of the advantages and limitations of constant pressure versus constant flow rate gradient elution separation in supercritical fluid chromatography.  

PubMed

This study reports on the possible advantages of switching from constant flow (cF) based gradient elution separations to constant pressure (cP) based ones in Supercritical fluid chromatography (SFC) by means of mathematical models. All the important parameters (e.g. viscosity) were fitted as a function of pressure and mol% methanol in CO2. It is shown that when switching towards a cP approach in SFC, a time gain of 34% at the end of a 0 to 50% methanol in CO2 gradient is expected. Actual analysis time gains depend on the point at which it is evaluated (e.g. up to 41% after the equilibration step). Due to the dependence of retention on density, cF- and cP-mode do not yield the same selectivity even if the same volumetric-based gradient program is used. Because the components experience a higher average pressure in the cP-mode, the apparent retention factor is slightly lower. PMID:24041511

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

2013-10-18

207

Evaluation of a direct injection nebulizer interface for flow injection analysis and high performance liquid chromatography with inductively coupled plasma-atomic emission spectroscopic detection  

SciTech Connect

A direct injection nebulizer (DIN) was designed, developed, and evaluated to determine its potential utilization as an effective interface for flow injection analysis (FIA) and high performance liquid chromatography (HPLC) coupled with inductively coupled plasma-atomic emission spectroscopic detection. The analytical figures of merit for the DIN when used as an interface for FIA-ICP-AES were found to be comparable to or better than those obtained with conventional pneumatic nebulization in terms of limits of detection (LODs), reproducibility, linearity, and interelement effects. Stable plasma operation was maintained for the DIN sample introduction of a variety of pure organic solvents, including acetonitrile, methanol, methylisobutylketone, and pyridine. The HPLC-DIN-ICP-AES facility was specifically applied for the speciation of inorganic and organometallic species contained in synthetic mixtures, vanilla extracts, and a variety of energy-related materials, such as shale oil process water, coal extracts, shale oil, crude oil, and an SRC II. Suggestions for future research are also considered. 227 refs., 44 figs., 15 tabs.

LaFreniere, K.E.

1986-06-01

208

Simultaneous determination of Cr(III) and Cr(VI) in tannery wastewater using low pressure ion chromatography combined with flow injection spectrophotometry.  

PubMed

Trivalent and hexavalent chromium have been successfully separated and determined using low pressure ion chromatography combined with flow injection spectrophotometric analysis (LPIC-FIA). A column packed with crosslinking starch microspheres was used for on-line separation of Cr(III) from Cr(VI) in a flow-injection system because of its absorptive effect on Cr(III). To determine the concentration of Cr(III) and Cr(VI) in samples, we used 3.0 mmol/L nitric acid to elute adsorbed Cr(III) from the column and then used ceric sulfate-sulfuric acid as oxidant to convert all Cr(III) into Cr(VI). Then, Cr(VI) directly came from the samples and Cr(VI) came from Cr(III) successively formed a amaranthine complex with diphenycarbazide and the complex shows a maximum absorption at 530 nm. Analytical parameters including the concentration of eluent and oxidant solution, oxidizing temperature, length of oxidizing reaction coil, reaction coil and injection coil, interfering effects, etc., were optimized. The limit of detection was 1.25 ?g/L for Cr(VI) and 3.76 ?g/L for Cr(III). The linear relationship between absorption with the concentration of Cr(VI) and Cr(III) was 0.001-1.000 mg/L and 0.030-1.000 mg/L with correlation coefficients of 0.9995 and 0.9994, respectively. The relative standard deviation of Cr(VI) and Cr(III) was 1.21% and 1.66%, respectively (n=10). Major cations and anions did not show any interference. We validated this method through certified reference materials and through measuring the recovery in tannery wastewater. PMID:22209249

Chen, Shujuan; Zhang, Xinshen; Yu, Lingyun; Wang, Li; Li, Hui

2012-03-01

209

Radial wedge flange clamp  

DOEpatents

A radial wedge flange clamp comprising a pair of flanges each comprising a plurality of peripheral flat wedge facets having flat wedge surfaces and opposed and mating flat surfaces attached to or otherwise engaged with two elements to be joined and including a series of generally U-shaped wedge clamps each having flat wedge interior surfaces and engaging one pair of said peripheral flat wedge facets. Each of said generally U-shaped wedge clamps has in its opposing extremities apertures for the tangential insertion of bolts to apply uniform radial force to said wedge clamps when assembled about said wedge segments.

Smith, Karl H. (Yorktown, VA)

2002-01-01

210

Radial cutting torch  

Microsoft Academic Search

The project`s aim is to complete development of the Radial Cutting Torch, a pyrotechnic cutter, for use in all downhole tubular cutting operations in the petroleum industry. Project objectives are to redesign and pressure test nozzle seals to increase product quality, reliability, and manufacturability; improve the mechanical anchor to increase its temperature tolerance and its ability to function in a

1997-01-01

211

Radial Inflow Turboexpander Redesign  

Microsoft Academic Search

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

William G. Price

2001-01-01

212

Radial velocity moments of dark matter haloes  

E-print Network

Using cosmological N-body simulations we study the radial velocity distribution in dark matter haloes focusing on the lowest-order even moments, dispersion and kurtosis. We determine the properties of ten massive haloes in the simulation box approximating their density distribution by the NFW formula characterized by the virial mass and concentration. We also calculate the velocity anisotropy parameter of the haloes and find it mildly radial and increasing with distance from the halo centre. The radial velocity dispersion of the haloes shows a characteristic profile with a maximum, while the radial kurtosis profile decreases with distance starting from a value close to Gaussian near the centre. We therefore confirm that dark matter haloes possess intrinsically non-Gaussian, flat-topped velocity distributions. We find that the radial velocity moments of the simulated haloes are quite well reproduced by the solutions of the Jeans equations obtained for the halo parameters with the anisotropy measured in the simulations. We also study the radial velocity moments for a composite cluster made of ten haloes out to ten virial radii. In this region the velocity dispersion decreases systematically to reach the value of the background, while kurtosis increases from below to above the Gaussian value of 3 signifying a transition from a flat-topped to a strongly peaked velocity distribution with respect to the Gaussian, which can be interpreted as the dominance of ordered flow with a small dispersion. We illustrate the transition by showing explicitly the velocity distribution of the composite cluster in a few radial bins.

Radoslaw Wojtak; Ewa L. Lokas; Stefan Gottloeber; Gary A. Mamon

2005-03-17

213

Axonemal radial spokes  

PubMed Central

The radial spoke (RS) is a complex of at least 23 proteins that works as a mechanochemical transducer between the central?pair apparatus and the peripheral microtubule doublets in eukaryotic flagella and motile cilia. The RS contributes to the regulation of the activity of dynein motors, and thus to flagellar motility. Despite numerous biochemical, physiological and structural studies, the mechanism of the function of the radial spoke remains unclear. Detailed knowledge of the 3D structure of the RS protein complex is needed in order to understand how RS regulates dynein activity. Here we review the most important findings on the structure of the RS, including results of our recent cryo?electron tomographic analysis of the RS protein complex. PMID:22754630

Pigino, Gaia; Ishikawa, Takashi

2012-01-01

214

Variable stator radial turbine  

NASA Technical Reports Server (NTRS)

A radial turbine stage with a variable area nozzle was investigated. A high work capacity turbine design with a known high performance base was modified to accept a fixed vane stagger angle moveable sidewall nozzle. The nozzle area was varied by moving the forward and rearward sidewalls. Diffusing and accelerating rotor inlet ramps were evaluated in combinations with hub and shroud rotor exit rings. Performance of contoured sidewalls and the location of the sidewall split line with respect to the rotor inlet was compared to the baseline. Performance and rotor exit survey data are presented for 31 different geometries. Detail survey data at the nozzle exit are given in contour plot format for five configurations. A data base is provided for a variable geometry concept that is a viable alternative to the more common pivoted vane variable geometry radial turbine.

Rogo, C.; Hajek, T.; Chen, A. G.

1984-01-01

215

Paper Chromatography  

NSDL National Science Digital Library

This is a site with experiments that provide a brief introduction to the idea of separation of components in a mixture and a set of instructions for students for separating colored compounds by paper chromatography (on coffee filters). The appropriate audience would be students in a high-school or introductory, non major college chemistry class.

Reeves, James H.

2011-05-19

216

Spotting Chromatography  

NSDL National Science Digital Library

In this mini-lab students will use chromatography to compare the mobile phase and the stationary phases of different inks used in marking pens. They will also determine the polarity of the solvents and inks. Finally, the students will use their calculated information to solve a crime.

217

Ion chromatography  

Microsoft Academic Search

Ion chromatography makes it possible to separate and measure low concentrations of up to 8 or 10 different anions in a single chromatographic run that takes only a few minutes. The method also works well for cations. Alkali metal ions, ammonium, magnesium, calcium, strontium, and a growing list of other metal cations and amine cations can also be rapidly separated

James S. Fritz

1987-01-01

218

Gas Chromatography  

NSDL National Science Digital Library

This site contains a brief introduction to the concepts of injection and detection in gas chromatography, focusing on the split/splitless injection port and flame ionization detectors. The treatment is similar to that in analytical chemistry textbooks, and includes detailed illustrations.

2011-05-25

219

Ion Chromatography.  

ERIC Educational Resources Information Center

Accurate for the analysis of ions in solution, this form of analysis enables the analyst to directly assay many compounds that previously were difficult or impossible to analyze. The method is a combination of the methodologies of ion exchange, liquid chromatography, and conductimetric determination with eluant suppression. (Author/RE)

Mulik, James D.; Sawicki, Eugene

1979-01-01

220

Anal. Chem. 1994,66,168-176 Classification of Countercurrent Chromatography Solvent  

E-print Network

Anal. Chem. 1994,66,168-176 Classification of Countercurrent Chromatography Solvent Systems Cedex 05, France Solvent systems used for countercurrent chromatography (CCC) have been classified predictionof the experimental flow behavior in CCC. Countercurrent chromatography (CCC) is a separation method

Wesfreid, José Eduardo

221

Molecular size and mass distributions of native starches using complementary separation methods: asymmetrical flow field flow fractionation (A4F) and hydrodynamic and size exclusion chromatography (HDC-SEC).  

PubMed

Starch consists of a mixture of two ?-glucans built mainly upon ?-(1,4) linkages: amylose, an essentially linear polymer, and amylopectin, a branched polymer containing 5-6% of ?-(1,6) linkages. The aim of the present work was to analyze the structural properties of native starches displaying different amylose-to-amylopectin ratios and arising from different botanical sources, using asymmetrical flow field flow fractionation (A4F) and a combination of hydrodynamic and size-exclusion chromatography (HDC-SEC) coupled with multiangle laser light scattering, online quasi-elastic light scattering, and differential refractive index techniques. The procedure, based upon dimethyl sulfoxide pretreatment and then solubilization in water, generates a representative injected sample without altering the initial degree of polymerization. The amylopectin weight-average molar masses and radii of gyration were around 1.0 × 10(8)-4.8 × 10(8) g mol(-1) and 110-267 nm, respectively. For each starch sample, the hydrodynamic radius (R(H)) distributions and the molar mass distributions obtained from the two fractionation systems coupled with light scattering techniques were analyzed. The size determination scales were extended by means of R(H) calibration curves. HDC-SEC and A4F data could be matched. However, A4F enabled a better separation of amylopectins and therefore an enhanced structural characterization of the starches. The two advantages of this experimental approach are (1) it can directly obtain distributions as a function of both molar mass and size, while taking account of sample heterogeneity, and (2) it is possible to compare the results obtained using the different techniques through the direct application of R(H) distributions. PMID:20878394

Rolland-Sabaté, Agnès; Guilois, Sophie; Jaillais, Benoît; Colonna, Paul

2011-02-01

222

Radial parallel plate flow with mechanical agitation  

E-print Network

Computer processors have significant and rising cooling requirements, with electronics cooling estimated to consume 1% of global energy consumption. An integrated fan heat sink was designed to help alleviate this issue, ...

Crane, Jackson T

2013-01-01

223

An inverse design method for radial turbomachines  

NASA Astrophysics Data System (ADS)

The calculation of compressible flow by computing the velocities and density throughout the three dimensional flow field is described. A second, approximate approach to solve the compressible flow problem is presented. In this approach the variation of density in the pitchwise direction is neglected and an approximate form of the continuity equation is used. In order to evaluate the method experimentally and assess the practical feasibility of the application of three dimensional blade geometries, a high speed small diameter radial inflow turbine was designed. The performance of this turbine is compared with that of three baseline impellers. The method is validated numerically by computing the flow through the designed impeller using inviscid and viscous flow analysis methods.

Zangeneh, M.

224

Radial cutting torch  

SciTech Connect

The project`s aim is to complete development of the Radial Cutting Torch, a pyrotechnic cutter, for use in all downhole tubular cutting operations in the petroleum industry. Project objectives are to redesign and pressure test nozzle seals to increase product quality, reliability, and manufacturability; improve the mechanical anchor to increase its temperature tolerance and its ability to function in a wider variety of wellbore fluids; and redesign and pressure test the RCT nozzle for operation at pressures from 10 to 20 ksi. The proposal work statement is included in the statement of work for the grant via this reference.

Robertson, M.C.

1997-01-08

225

Harvesting the radial artery  

PubMed Central

The radial artery (RA) has emerged as an important arterial graft for coronary bypass surgery. With improving five-year patency rates and increasing uptake, great attention has been focused on the optimal conduit harvesting technique. We herein present our approach to RA harvesting. Prerequisites of a successful harvest include adherence to important anatomical landmarks, protection of the sensory innervation to the volar forearm, and meticulous handling of the RA branches. Regardless of the harvesting methodology chosen, adherence to a “no-touch” technique will optimize the patency and durability of the RA conduit. PMID:23977633

Osterday, Robert M.; Brodman, Richard F.

2013-01-01

226

Radial reflection diffraction tomography  

DOEpatents

A wave-based tomographic imaging method and apparatus based upon one or more rotating radially outward oriented transmitting and receiving elements have been developed for non-destructive evaluation. At successive angular locations at a fixed radius, a predetermined transmitting element can launch a primary field and one or more predetermined receiving elements can collect the backscattered field in a "pitch/catch" operation. A Hilbert space inverse wave (HSIW) algorithm can construct images of the received scattered energy waves using operating modes chosen for a particular application. Applications include, improved intravascular imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts having existing access holes.

Lehman, Sean K.

2012-12-18

227

Radial Reflection diffraction tomorgraphy  

DOEpatents

A wave-based tomographic imaging method and apparatus based upon one or more rotating radially outward oriented transmitting and receiving elements have been developed for non-destructive evaluation. At successive angular locations at a fixed radius, a predetermined transmitting element can launch a primary field and one or more predetermined receiving elements can collect the backscattered field in a "pitch/catch" operation. A Hilbert space inverse wave (HSIW) algorithm can construct images of the received scattered energy waves using operating modes chosen for a particular application. Applications include, improved intravascular imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts having existing access holes.

Lehman, Sean K

2013-11-19

228

Chromatography Lab  

NSDL National Science Digital Library

To increase students' awareness of possible invisible pollutants in drinking water sources, students perform an exciting lab requiring them to think about how solutions and mixtures exist even in unsuspecting places such as ink. They use alcohol and chromatography paper to separate the components of black and colored marker ink. Students witness first-hand how components of a solution can be separated, even when those individual components are not visible in solution.

GK-12 Program,

229

Fundamentals of gas chromatography  

SciTech Connect

On line gas chromatography is today being chosen more and more in the natural gas industry for monitoring of gas quality. The calculations of the gas volumes in modern electronic flow meters requires not only BTU (A BTU, British Thermal Unit, is a measure of heat) information, but specific gravity, Mol. % CO{sub 2} and Mol. % N{sub 2} as well. In addition, the current AGA-8 supercompressibility equations also require a complete analysis for the {open_quotes}detailed method{close_quotes} of calculation of F{sub pv}. Most natural gas custody transfer contracts today use MMBTU rather than MCF as the accounting units of gas transfer. Also, modern micropacked columns are providing faster cycle times for {open_quotes}time critical{close_quotes} BTU measurement applications. For these reasons mentioned above, and the fact that the installation requirements for chromatographs are less stringent than calorimetric methods, the use of gas chromatographs has become standard practice. There are two general classes of chromatography; laboratory chromatography and {open_quotes}on-line{close_quotes} or process chromatography. The scope of this paper is limited to on-line chromatography. The basics of each are very similar. The chromatographic process is one in which mixtures of volatile compounds are separated by molecular size, boiling point, and polarity. Natural gas is a mixture in which the compounds vary in size from nitrogen, N2, at the smallest, to the C6 fraction at the largest. Incidentally, the C6 fraction is called that because it is composed of up to 150 different compounds. In natural gas, as the molecular size of each component gets larger, there is a smaller and smaller amount of each component until the entire C6 {open_quotes}peak{close_quotes} is only a fraction of one per cent of the total compounds present.

Kizer, P.E. [Applied Automation, Inc./Hartmann and Braun, Houston, TX (United States)

1995-12-01

230

Bisphenol A determination in baby bottles by chemiluminescence enzyme-linked immunosorbent assay, lateral flow immunoassay and liquid chromatography tandem mass spectrometry.  

PubMed

Two immunoassays, a Lateral Flow ImmunoAssay (LFIA) based on colloidal gold nanoparticle labels and an indirect competitive chemiluminescence enzyme-linked immunosorbent assay (CL-ELISA), were developed and a high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was optimized to assess the possible release of bisphenol A (BPA, 4,4'-isopropylidenediphenol) from different plastic baby bottles treated with simulating solutions. Coating conjugate concentration, anti-BPA antibody dilution, incubation time of the primary and secondary antibodies, and tolerance to different organic solvents were optimized to obtain the best performance of the ELISA with chemiluminescent end-point detection. The influence of different buffers on LFIA performance was also evaluated. Both methods showed good repeatability (mean CV value around 13%) and sensitivity. Reproducibility tests for CL-ELISA gave a mean CV value of about 25%. The IC50 and Limit of Detection (LOD) values of CL-ELISA were 0.2 and 0.02 ng mL(-1), respectively. The LOD of LFIA was 0.1 ?g mL(-1). A LC-MS/MS method was also optimized. The separation was performed in a C18 column with a triple-quadrupole mass spectrometer with electrospray ionisation interface. The method showed a good linearity in the range 2 to 500 ng mL(-1), with a regression coefficient of 0.998. In the simulating solutions the detection and quantification limits, calculated by the signal to noise level of 3 (S/N = 3), were 5.8 ng mL(-1) and 17.4 ng mL(-1), respectively. This limit of quantification was about 3 and 35 times lower than the permitted limits set by the official method CEN/TS 13130-13 (0.05 ?g mL(-1)) and by the Directive 2004/19/EC (0.6 ?g mL(-1)), respectively. The methods were applied to determine BPA release from baby bottles, performing repeated procedures according to EU and national regulations. The results demonstrated that no BPA migration from the tested plastic materials occurred with only one exception. The migrated amount, above the regulatory limits, was detected by all the mentioned assays. PMID:24223419

Maiolini, Elisabetta; Ferri, Elida; Pitasi, Agata Laura; Montoya, Angel; Di Giovanni, Manuela; Errani, Ermanno; Girotti, Stefano

2014-01-01

231

Radial Reflection Diffraction Tomography  

SciTech Connect

We develop a wave-based tomographic imaging algorithm based upon a single rotating radially outward oriented transducer. At successive angular locations at a fixed radius, the transducer launches a primary field and collects the backscattered field in a ''pitch/catch'' operation. The hardware configuration, operating mode, and data collection method is identical to that of most medical intravascular ultrasound (IVUS) systems. IVUS systems form images of the medium surrounding the probe based upon ultrasonic B-scans, using a straight-ray model of sound propagation. Our goal is to develop a wave-based imaging algorithm using diffraction tomography techniques. Given the hardware configuration and the imaging method, we refer to this system as ''radial reflection diffraction tomography.'' We consider two hardware configurations: a multimonostatic mode using a single transducer as described above, and a multistatic mode consisting of a single transmitter and an aperture formed by multiple receivers. In this latter case, the entire source/receiver aperture rotates about the fixed radius. Practically, such a probe is mounted at the end of a catheter or snaking tube that can be inserted into a part or medium with the goal of forming images of the plane perpendicular to the axis of rotation. We derive an analytic expression for the multimonostatic inverse but ultimately use the new Hilbert space inverse wave (HSIW) algorithm to construct images using both operating modes. Applications include improved IVUS imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts with existing access holes.

Lehman, S K; Norton, S J

2003-10-10

232

Chiral separation by SMB chromatography  

Microsoft Academic Search

The paper deals with chiral separation by simulated moving bed (SMB) chromatography. A model for the prediction of the cyclic steady-state performance of the SMB, based on the analogy with the true moving bed (TMB), is developed assuming multicomponent adsorption equilibria, axial dispersion flow and the linear driving force approximation to describe the intraparticle mass transfer rate. The simulation package

Lu??s S. Pais; José M. Loureiro; Al??rio E. Rodrigues

2000-01-01

233

Are RRab stars fully radial?  

NASA Astrophysics Data System (ADS)

Thanks to the space missions CoRoT and Kepler new oscillation frequencies have been discovered in the Fourier spectra of Blazhko RR Lyrae stars. The period doubling (PD) yields half-integer frequencies between the fundamental mode and its harmonics. In many cases the first and/or second radial overtone frequencies also appear temporally. Some stars show extra frequencies that were identified as potential non-radial modes. We show here that all these frequencies can be explained by pure radial pulsation as linear combinations of the frequencies of radial fundamental and overtone modes.

Benk?, József M.; Szabó, Róbert

2014-02-01

234

Fundamentals of preparative and nonlinear chromatography  

SciTech Connect

The second edition of Fundamentals of Preparative and Nonlinear Chromatography is devoted to the fundamentals of a new process of purification or extraction of chemicals or proteins widely used in the pharmaceutical industry and in preparative chromatography. This process permits the preparation of extremely pure compounds satisfying the requests of the US Food and Drug Administration. The book describes the fundamentals of thermodynamics, mass transfer kinetics, and flow through porous media that are relevant to chromatography. It presents the models used in chromatography and their solutions, discusses the applications made, describes the different processes used, their numerous applications, and the methods of optimization of the experimental conditions of this process.

Guiochon, Georges A [ORNL; Felinger, Attila [ORNL; Katti, Anita [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Shirazi, Dean G [unknown

2006-02-01

235

Radial gate hoist mechanisms mounted above radial gates, view to ...  

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

Radial gate hoist mechanisms mounted above radial gates, view to the east - Wellton-Mohawk Irrigation System, Wasteway No. 1, Wellton-Mohawk Canal, North side of Wellton-Mohawk Canal, bounded by Gila River to North & the Union Pacific Railroad & Gila Mountains to south, Wellton, Yuma County, AZ

236

Atomic Force Microscope Mediated Chromatography  

NASA Technical Reports Server (NTRS)

The atomic force microscope (AFM) is used to inject a sample, provide shear-driven liquid flow over a functionalized substrate, and detect separated components. This is demonstrated using lipophilic dyes and normal phase chromatography. A significant reduction in both size and separation time scales is achieved with a 25-micron-length column scale, and one-second separation times. The approach has general applications to trace chemical and microfluidic analysis. The AFM is now a common tool for ultra-microscopy and nanotechnology. It has also been demonstrated to provide a number of microfluidic functions necessary for miniaturized chromatography. These include injection of sub-femtoliter samples, fluidic switching, and sheardriven pumping. The AFM probe tip can be used to selectively remove surface layers for subsequent microchemical analysis using infrared and tip-enhanced Raman spectroscopy. With its ability to image individual atoms, the AFM is a remarkably sensitive detector that can be used to detect separated components. These diverse functional components of microfluidic manipulation have been combined in this work to demonstrate AFM mediated chromatography. AFM mediated chromatography uses channel-less, shear-driven pumping. This is demonstrated with a thin, aluminum oxide substrate and a non-polar solvent system to separate a mixture of lipophilic dyes. In conventional chromatographic terms, this is analogous to thin-layer chromatography using normal phase alumina substrate with sheardriven pumping provided by the AFM tip-cantilever mechanism. The AFM detection of separated components is accomplished by exploiting the variation in the localized friction of the separated components. The AFM tip-cantilever provides the mechanism for producing shear-induced flows and rapid pumping. Shear-driven chromatography (SDC) is a relatively new concept that overcomes the speed and miniaturization limitations of conventional liquid chromatography. SDC is based on a sliding plate system, consisting of two flat surfaces, one of which has a recessed channel. A fluid flow is produced by axially sliding one plate past another, where the fluid has mechanical shear forces imposed at each point along the channel length. The shear-induced flow rates are very reproducible, and do not have pressure or voltage gradient limitations. SDC opens up a new range of enhanced separation kinetics by permitting the sample confinement with submicron dimensions. Small, highly confined liquid is advantageous for chromatographic separation because the separation rate is known to scale according to the square of the confined sample diameter. In addition, because shear-driven flows are not limited by fluid velocity, shear-driven liquid chromatography may provide up to 100,000 plate efficiency.

Anderson, Mark S.

2013-01-01

237

Numerical simulation of radial compressor stages with seals and technological holes  

NASA Astrophysics Data System (ADS)

Article describes numerical simulations of an air flow in radial compressor stages in the NUMECA CFD software. Four different radial compressor stages were solved in this article. During the tasks evaluating the stepped and straight impeller seals and technological holes influence on working characteristics and the flow field was observed. Also the CFD results comparison with results from the empiric design tool is described.

Syka, Tomáš; Lu?á?ek, Ond?ej; K?ourek, Jind?ich

2014-03-01

238

Gas Chromatography  

NSDL National Science Digital Library

This video, distributed on YouTube by the Royal Society of Chemistry, is on the basic principles of Gas Chromatography. This video is a short primer which introduces the technique and instrumentation. There are many assumptions that are made in the presentation of this material, due to the fact the video is meant to be a basic introduction. The ultimate strength of this video is the general nature of the content that makes it appealing to a wide audience. The video may be most appropriate in a lower-level general education science course (i.e forensic science) or as a quick orientation video for instrumental analysis students. The GC-FID and GC-MS are highlighted. Running time for the video is 5:17.

2011-05-26

239

Chem 355 Jasperse Gas Chromatography-Mass Spectroscopy BACKGROUND Every type of chromatography depends on the distribution of a substance  

E-print Network

GC-MS 35 Chem 355 Jasperse Gas Chromatography-Mass Spectroscopy BACKGROUND Every type of chromatography depends on the distribution of a substance between two phases, a mobile phase and a stationary phase. Recall that in the liquid/solid chromatography the mobile phase was liquid flowing over

Jasperse, Craig P.

240

Atomic force microscope mediated chromatography.  

PubMed

An atomic force microscope (AFM) is presented as an instrument for rapid, miniaturized chromatography. The AFM is used to inject a sample, provide shear driven liquid flow over a functionalized substrate, and detect separated components. The components are then analyzed with surface enhanced Raman spectroscopy using AFM deposition of gold nanoparticles on the separated bands. This AFM mediated chromatography (AFM-MC) is demonstrated using lipophilic dyes and normal phase chemistry. A significant reduction in both size and separation time scales is achieved with 25 ?m length scale and 1 s separation times. AFM-MC has general applications to trace chemical analysis and microfluidics. PMID:23464258

Anderson, M S

2013-02-01

241

Entropy generation of radial rotation convective channels  

NASA Astrophysics Data System (ADS)

The exchange of heat between two fluids is established by radial rotating pipe or a channel. The hotter fluid flows through the pipe, while the cold fluid is ambient air. Total length of pipe is made up of multiple sections of different shape and position in relation to the common axis of rotation. In such heat exchanger the hydraulic and thermal irreversibility of the hotter and colder fluid occur. Therefore, the total entropy generated within the radial rotating pipe consists of the total entropy of hotter and colder fluid, taking into account all the hydraulic and thermal irreversibility of both fluids. Finding a mathematical model of the total generated entropy is based on coupled mathematical expressions that combine hydraulic and thermal effects of both fluids with the complex geometry of the radial rotating pipe. Mathematical model follows the each section of the pipe and establishes the function between the sections, so the total generated entropy is different from section to section of the pipe. In one section of the pipe thermal irreversibility may dominate over the hydraulic irreversibility, while in another section of the pipe the situation may be reverse. In this paper, continuous analytic functions that connect sections of pipe in geometric meaning are associated with functions that describe the thermo-hydraulic effects of hotter and colder fluid. In this way, the total generated entropy of the radial rotating pipe is a continuous analytic function of any complex geometry of the rotating pipe. The above method of establishing a relationship between the continuous function of entropy with the complex geometry of the rotating pipe enables indirect monitoring of unnecessary hydraulic and thermal losses of both fluids. Therefore, continuous analytic functions of generated entropy enable analysis of hydraulic and thermal irreversibility of individual sections of pipe, as well as the possibility of improving the thermal-hydraulic performance of the rotating pipe consisting of n sections. Analytical modeling enabled establishing of a mathematical model of the total generated entropy in a radial rotating pipe, while the generated entropy of models with radial rotating pipe were determined by experimental testing, with comparisons of the achieved results.

Ali?, Fikret

2012-03-01

242

Instrumentation: Ion Chromatography.  

ERIC Educational Resources Information Center

Discusses the importance of ion chromatography in separating and measuring anions. The principles of ion exchange are presented, along with some applications of ion chromatography in industry. Ion chromatography systems are described, as well as ion pair and ion exclusion chromatography, column packings, detectors, and programming. (TW)

Fritz, James S.

1987-01-01

243

Principles and Methods Chromatography  

E-print Network

Edition AC 18-1022-29 Principles and Methods Affinity Chromatography #12;Antibody Purification-1142-75 Protein Purification Handbook 18-1132-29 Ion Exchange Chromatography Principles and Methods 18-1114-21 Affinity Chromatography Principles and Methods 18-1022-29 Hydrophobic Interaction Chromatography Principles

Lebendiker, Mario

244

On the pressure distribution for radial outflow between parallel disks  

SciTech Connect

This paper solves a difference equation model for a thin channel radial diffuser with special attention given to the radial pressure distribution at low Reynolds number. It has been noted that pressures less than ambient pressure are produced in radial flow at low Reynolds number even though the gas supplied is at a higher source pressure than the ambient pressure. The object of this paper is to explain the phenomena of pressures lower than ambient pressure being produced by gases flowing through a thin channel radial diffuser under positive pressure from the central inlet. The resulting application was to show the feasibility of a suction device using positive air pressure. This device is nothing more than a plate with a centrally located gas inlet hole. The lower surface of the diffuser is the contact surface of the object to be lifted. This flow is of interest in a number of practical applications such as (a) air bearings, (b) radial diffusers, (c) the loss of lift in ground effect on vertical take-off aircraft, (d) rotating heat exchangers, (e) air cushion vehicles, and (f) centrifugal compressors.

Kettleborough, C.F.; Goldsberry, F. [Texas A and M Univ., College Station, TX (United States). Dept. of Mechanical Engineering

1998-12-31

245

Effect of parallel segmented flow chromatography on the height equivalent to a theoretical plate. I-performance of 4.6mm×30mm columns packed with 3.0?m Hypurity-C18 fully porous particles.  

PubMed

The mass transfer kinetics in short and wide 4.6mm×30mm columns packed with 3.0?m Hypurity-C18 fully porous particles were measured for three different configurations of the inlet sample distribution and outlet sample collection: (1) both the inlet and outlet column endfittings are standard, (2) the inlet endfitting is standard while the outlet endfitting allows parallel segmentation of the exiting flow between a central and a peripheral region across the column diameter, and (3) both the inlet and outlet endfittings allow a parallel segmentation of the flow entering and exiting the column, respectively. The total reduced heights equivalent to a theoretical plate (HETP) were carefully measured, using the first and second central moments of the elution band profiles, obtained by its accurate numerical integration. The longitudinal diffusion term was measured at the lowest experimental reduced velocity applied. The solid-liquid mass transfer resistance was estimated from measurements of the intra-particle diffusivity using the Torquato's model of effective diffusion in packed beds. The trans-channel and short-range interchannel eddy diffusion HETP terms were taken from data obtained by solving numerically the Navier-Stokes equations and simulating advective-diffusive transport in computer-generated random sphere packings. The results clearly show that the trans-column eddy diffusion HETP term can account for up to 85% of the total intrinsic HETP (corrected for extra-column contributions) of the standard columns. Parallel segmented flow chromatography can reduce this contribution by half at high velocities, by eliminating most of the baseline peak tailing. This holds true irrespective of the retention factor of the analyte. It was found also that segmenting the inlet/outlet flow increases detection sensitivity by 25-50% for peaks with large to small retention factors, respectively. In practice, the advantage of parallel segmented flow chromatography in gradient elution (thin peak widths) is essentially limited by post-column bandspreading and diffusion in the dwell volume of the instrument used. Analyst should minimize post-column bandspreading (caused by connectors and detection cell volume) and synchronize the eluent composition in the peripheral and central inlet ports of the column, by using two separate pumps with appropriate dwell volumes. PMID:23706347

Gritti, Fabrice; Guiochon, Georges

2013-07-01

246

The identification and quantification of a high molecular weight light stabilizer in polycarbonate by application of an online coupling of size exclusion chromatography in stopped flow mode with pyrolysis gas chromatography time of flight mass spectroscopy.  

PubMed

The identification and quantification of a high molecular weight light stabilizer (Uvinul 3030™) in an unknown polycarbonate sample was achieved through the application of SEC-Py-TOF-GCMS. A size exclusion column optimized to achieve resolution in the lower mass range was applied to allow the fractionation of an individual additive peak. A commercially available sampling interface was operated in stop flow mode and fractions were pyrolyzed to allow chromatographic separation of the fragments of the otherwise non-volatile stabilizer. After identification on the basis of accurate mass and elemental composition of the additive the quantification was compared using the available SEC-UV and SEC-PY-GC-TOFMS data. The resulting method provided a high degree of certainty in identification and flexibility in quantification expected to be applicable to other additives of similar volatilities or functional class. PMID:25160954

Brander, Eric; Wold, Christian

2014-10-01

247

Effect of parallel segmented flow chromatography on the height equivalent to a theoretical plate II - performances of 4.6mm×30mm columns packed with 2.6?m Accucore-C18 superficially porous particles.  

PubMed

The reduced trans-column (or long-range eddy dispersion) height equivalent to a theoretical plate (HETP) of short and wide 4.6mm×30mm columns packed with 2.6?m Accucore-C18 superficially porous particles was measured under conventional (no split flow) and parallel segmented (outlet and inlet) flow chromatography. The overall reduced HETP was derived from the true moments of the recorded concentration profiles. The longitudinal diffusion HETP term was measured at a very small flow rate (0.05mL/min). The solid-liquid mass transfer resistance was derived from the shell diffusivity, using the composite Garnett-Torquato model of effective diffusion in a heterogeneous system made of a dense packing of core-shell particles immersed in a continuous matrix (the eluent). The trans-channel and short-range interchannel eddy dispersion HETP terms were assumed to be equal to the calculated h data after solving the Navier-Stokes equation and simulating the advection-diffusion transport process. Experimental results confirmed that the optimum efficiency of these short columns was increased by a factor of about two. The ratio of the detection sensitivities on the PSFC stream and on a regular stream increased from 1 to 1.45 when the retention factor decreases from about 10 to 0.5. These phenomena are due to a strong reduction of the trans-column eddy dispersion HETP term. The system loses about 60% of the sample mass when only outlet skimming is carried out when the flow rate ratio of 55% is applied, as was done in this work. It loses about 50% of the sample when inlet/outlet segmentation is applied. In gradient elution, the peak capacity is increased by only 15%, due to post-column band spreading, which should imperatively be minimized when the outlet flow is split. PMID:24050598

Gritti, Fabrice; Guiochon, Georges

2013-11-01

248

Performance of vaned radial diffusers  

E-print Network

. At the inlet station, the flow angles for the high flow rate case are about 10 percent larger than those for the low flow rate, especially near the shroud side. The effect of the flow rate level on the yaw angle distributions decreases as the flow proceeds.... At the inlet station, the flow angles for the high flow rate case are about 10 percent larger than those for the low flow rate, especially near the shroud side. The effect of the flow rate level on the yaw angle distributions decreases as the flow proceeds...

Piemsomboon, Pornchai

2012-06-07

249

Asymmetric Flow Field Flow Fractionation of Aqueous C60 Nanoparticles with Size Determination by Dynamic Light Scattering and Quantification by Liquid Chromatography Atmospheric Pressure Photo-Ionization Mass Spectrometry  

EPA Science Inventory

A size separation method was developed for aqueous C60 fullerene aggregates (aqu/C60) using asymmetric flow field flow fractionation (AF4) coupled to a dynamic light scattering detector in flow through mode. Surfactants, which are commonly used in AF4, were avoided as they may al...

250

How radial clearance affects gas turbine plant parameter ratios  

Microsoft Academic Search

Accuracy in determining performance characteristics of gas turbine plants depends more than anything else on the stability of the geometric and thermodynamic variables over the engine flow passages in different operating modes. Results of theoretical investigations have shown that changes in the radial clearances (brought about in turn by changes in the thermal stress state of turbine parts) have a

K. B. Sarantsev; L. G. Korenevskii; Yu. A. Shevtsov; A. M. Temirov

1983-01-01

251

Fractures of the radial head.  

PubMed

Most fractures of the radial head are stable undisplaced or minimally displaced partial fractures without an associated fracture of the elbow or forearm or ligament injury, where stiffness following non-operative management is the primary concern. Displaced unstable fractures of the radial head are usually associated with other fractures or ligament injuries, and restoration of radiocapitellar contact by reconstruction or prosthetic replacement of the fractured head is necessary to prevent subluxation or dislocation of the elbow and forearm. In fractures with three or fewer fragments (two articular fragments and the neck) and little or no metaphyseal comminution, open reduction and internal fixation may give good results. However, fragmented unstable fractures of the radial head are prone to early failure of fixation and nonunion when fixed. Excision of the radial head is associated with good long-term results, but in patients with instability of the elbow or forearm, prosthetic replacement is preferred. This review considers the characteristics of stable and unstable fractures of the radial head, as well as discussing the debatable aspects of management, in light of the current best evidence. PMID:23365021

Duckworth, A D; McQueen, M M; Ring, D

2013-02-01

252

Erosion in radial inflow turbines. Volume 2: Balance of centrifugal and radial drag forces on erosive particles  

NASA Technical Reports Server (NTRS)

The particle motion in two-dimensional free and forced inward flowing vortices is considered. A particle in such a flow field experiences a balance between the aerodynamic drag forces that tend to drive erosive particles toward the axis, and centrifugal forces that prevent these particles from traveling toward the axis. Results predict that certain sizes of particles will achieve a stable orbit about the turbine axis in the inward flowing free vortex. In this condition, the radial drag force is equal to the centrifugal force. The sizes of particles that will achieve a stable orbit is shown to be related to the gas flow velocity diagram at a particular radius. A second analysis yields a description of particle sizes that will experience a centrifugal force that is greater than the radial component of the aerodynamic drag force for a more general type of particle motion.

Clevenger, W. B., Jr.; Tabakoff, W.

1974-01-01

253

The attenuation of sound propagating through a radial diffuser with absorptive walls  

Microsoft Academic Search

An analytical model for acoustic propagation through an idealized radial diffuser under zero flow conditions has been developed. The model has been used to generate a computer program which is capable of predicting radial attenuation for a variety of diffuser wall impedance combinations. Numerical results are presented for the following three cases: (1) one hard diffuser wall and one finite

D. K. Holger

1981-01-01

254

Determination of lincomycin in urine and some foodstuffs by flow injection analysis coupled with liquid chromatography and electrochemical detection with a preanodized screen-printed carbon electrode.  

PubMed

An electroanalytical method for the determination of lincomycin in feeds, honey, milk and urine was demonstrated in this study. The procedure employed a solid-phase extraction for the isolation of lincomycin from real samples. The antibiotic residues were subsequently analyzed by high-performance liquid chromatography (HPLC) coupled with a disposable electrochemical sensor. The use of a disposable sensor together with the application of solid-phase extraction is attractive in practical application and should be useful in fast screening assay. The electroanalysis of lincomycin was first investigated using a preanodized screen-printed carbon electrode (SPCE*). Note that the SPCE* holds the advantages of low cost and easy to handle. The analytical parameters, such as, preanodization potential, preanodization time, solution pH, detection potential, cartridge, wash solution, elute solution and mobile phase, were further studied in detail. Under optimized conditions, the linear detection range for lincomycin is up to 1mM (correlation coefficient=0.999) with a detection limit of 0.08microM (S/N=3) and a quantification limit of 0.27microM (S/N=10). The applicability of the method was successfully demonstrated in real sample analysis. PMID:19285928

Chiu, Mei-Hsin; Yang, Hsueh-Hui; Liu, Chi-Ho; Zen, Jyh-Myng

2009-04-01

255

Use of on-line stop-flow heart-cutting two-dimensional high performance liquid chromatography for simultaneous determination of 12 major constituents in tartary buckwheat (Fagopyrum tataricum Gaertn).  

PubMed

The use of two-dimensional liquid chromatography (2D-LC) for quantification studies presents challenges with respect to repeatability, precision, and robustness. The present study used an on-line stop-flow heart-cutting 2D-LC system to determine 12 chemical constituents in tartary buckwheat. A combination of various stationary phases was developed and bridged using two switch valves as the interface. Hydrophilic interaction chromatography was chosen for separation in the first dimension ((1)D), and mixed mode stationary phases (an amide polar-embedded phase and alkyl-phenyl phase) were used in parallel for separation in the second dimension ((2)D). The mobile phase comprised acetonitrile and water containing 0.03% aqueous phosphoric acid. The sample was separated into two fractions on the (1)D column (HILIC-10 column) using 5% acetonitrile. One fraction, mainly comprising flavonoids, was directly eluted onto the head of (2)D column (Polar Advantage II column) and further separated using a linear gradient of 11-23% acetonitrile. The second fraction, containing phenylpropanoid glycosides, was trapped on the (1)D column. This retained fraction was back-flushed onto the (2)D column (Phenyl-1 column) and separated using a linear gradient of 35-43% acetonitrile. An on-line stop-flow heart-cutting 2D-LC system was successfully developed with column switching and back-flush. This 2D-LC system was validated and was able to simultaneously determine 12 major components in tartary buckwheat: seven flavonoids, four phenylpropanoid glycosides, and N-trans-feruloyltyramine. The system showed good performance with respect to linearity (r>0.996), repeatability (RSD, relative standard deviation<3.4%), intra-day and inter-day precision (RSD<4.6%), recovery (91.2-108%), limit of detection (LOD) (0.05-0.21?g/mL), and limit of quantification (LOQ) (0.10-0.41?g/mL). The on-line stop-flow heart-cutting 2D-LC system offers a potential approach to analyze compounds, which have similar structures but different polarities, in herbal medicines. PMID:23870547

Ren, Qiang; Wu, Caisheng; Zhang, Jinlan

2013-08-23

256

High Performance Liquid Chromatography  

E-print Network

HPLC - 1 High Performance Liquid Chromatography HPLC MEASUREMENT OF POLYCYCLIC AROMATIC HYDROCARBONS IN CIGARETTE SMOKE Last updated: June 17, 2014 #12;HPLC - 2 High Performance Liquid Chromatography identify as many PAH as possible in cigarette smoke using high performance liquid chromatography (HPLC

Nizkorodov, Sergey

257

Gas Chromatography -Mass Spectrometry  

E-print Network

GCMS - 1 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS OF ETHANOL AND BENZENE IN GASOLINE Last updated: June 17, 2014 #12;GCMS - 2 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS). The goal of this experiment is to separate the components in a sample of gasoline using Gas Chromatography

Nizkorodov, Sergey

258

Metal Affinity Chromatography (MAC)  

E-print Network

Fractogel® Metal Affinity Chromatography (MAC) Resins and Cartridges Tools for His·Tag® Fusion-MACTM Cartridges #12;2 Novagen · Fractogel Metal Affinity Chromatography (MAC) Resins Ni-MACTM , Co-MACTM and u-MACTM Metal Affinity Chromatography (MAC) Resins and Cartridges HI Ni2+ Ni2+ Ni2+ HISHISHI SHISHISHIS Ni2

Lebendiker, Mario

259

Isotope-ratio-monitoring gas chromatography methods for high-precision isotopic analysis of nanomole  

E-print Network

Isotope-ratio-monitoring gas chromatography methods for high-precision isotopic analysis and a commercially available continuous-flow, gas chromatography interface (the Finnigan Gas Bench II). This work

Bebout, Gray E.

260

Radial spreading of viscous-gravity currents with solidifying crust  

NASA Technical Reports Server (NTRS)

In the present investigation of solidifying-crust effects on the dynamics and surface morphology of radial viscous-gravity currents, polyethylene glycol inflows into the base of a tank holding a cold sucrose solution are used as analogs. As the radial current advanced away from the inlet, its surface solidified and deformed through a combination of folding anf fracturing. When cooling was sufficiently rapid, solid crust formed and caused the spreading rate to increase; progressively colder experiments revealed a sequence of surface morphologies resembling features of cooling lava flows and lava lakes, including multiarmed rift structures with shear offsets and bulbous lobate forms resembling pillow lavas on the ocean floor.

Fink, Jonathan H.; Griffiths, Ross W.

1990-01-01

261

Advancement in the modeling of pressure-flow for the guidance of development and scale-up of commercial-scale biopharmaceutical chromatography  

Microsoft Academic Search

This paper details the advancements made in the modeling of open column and packed bed pressure-flow. The theoretical description is a one-dimensional elasticity model. By accounting for the loss of intra-particle porosity through empiricism, and by systematically selecting the functional form of the elastic modulus from stress–strain data, this model can accurately predict several kinds of large-scale behavior from small-scale

Ronald N. Keener; Erik J. Fernandez; James E. Maneval; Roger A. Hart

2008-01-01

262

Exoplanet Detection: Radial Velocity Method  

NSDL National Science Digital Library

The Exoplanet Detection: The Radial Velocity Method model simulates the detection of exoplanets by using the radial velocity method and the Doppler effect. In this simulation the exoplanet orbits the star (sun-sized) in circular motion via Kepler's third law.  The radial velocity of the star is determined from the velocity of the exoplanet.  This velocity is then used to calculate the Doppler shift of the Fraunhofer lines of the star.  In practice it is the Doppler shift of the Fraunhofer lines of the star that are detected and from this the radial velocity is inferred.  From this the mass and orbital period and average exoplanet-star separation are determined.  In the simulation the star-exoplanet system is shown as seen from Earth (edge on view) and from space (overhead view), and with the star and exoplanet sizes not shown to the scale of the orbit.  In addition, the Fraunhofer lines are shown.  The radial velocites of stars are such that the Doppler shifts are small, to compensate you may snap to the Na line and use the right-hand side slider to zoom in on that line to see wavelength shift.  The mass of the exoplanet (relative to the mass of Jupiter), the average star-exoplant separation (in AU), and the inclination of the system relative to Earth can be changed. The simulation uses Java 3D, if installed, to render the view the star and exoplanet. If Java 3D is not installed, the simulation will default to simple 3D using Java.

Belloni, Mario

2010-06-29

263

On second propagation in radial fan casings  

NASA Astrophysics Data System (ADS)

Sound propagation in radial fan hollow casings was studied for cylindrical and spiral-shaped casings of the same volume and width. After measurement of the sound reflection through the different casings a monopole or dipole sound source of reduced expansion at the casing cut-off was introduced and the frequency responses in the intake and outflow canals determined. The influence of casing geometry and the flow in the casing on the rejection level and on the system frequency responses was determined. The applicability of the one-mode approximation for description of the frequency responses was verified. Torsional sound in the outflow canal can be reduced with a phase-variable sound source synchronous with the rotation frequency at the cut-off.

Bartenwerfer, M.; Gikadi, T.

1985-02-01

264

Effects of tip clearance of nozzle vanes on performance of radial turbine rotor  

Microsoft Academic Search

In radial turbines with variable nozzles, the flow downstream of the nozzles could be distorted by the leakage flow through the tip-clearance of the upstream nozzle vanes. To investigate the effects of flow distortion on the performance of turbine rotors, two rotors with different number of blades were tested for three types of distorted velocity distributions at the rotor inlet.

H. Hayami; M. Yamaguchi; Y. Senoo; Y. I. Hyun

1989-01-01

265

Simultaneous Quantification of ?9-Tetrahydrocannabinol, 11-nor-9-carboxy-Tetrahydrocannabinol, Cannabidiol and Cannabinol in Oral Fluid by MicroFlow-Liquid Chromatography-High Resolution Mass Spectrometry  

PubMed Central

?9-tetrahydrocannabinol (THC) is the primary target in oral fluid (OF) for detecting cannabis intake. However, additional biomarkers are needed to solve interpretation issues, such as the possibility of passive inhalation by identifying 11-nor-9-carboxy-THC (THCCOOH), and determining recent cannabis smoking by identifying cannabidiol (CBD) and/or cannabinol (CBN). We developed and comprehensively validated a microflow liquid chromatography (LC)–high resolution mass spectrometry method for simultaneous quantification of THC, THCCOOH, CBD and CBN in OF collected with the Oral-Eze® and Quantisal™ devices. One mL OF-buffer solution (0.25mL OF and 0.5mL of Oral-Eze buffer,1:3 dilution, or 0.75mL Quantisal buffer, 1:4 dilution) had proteins precipitated, and the supernatant subjected to CEREX™ Polycrom™ THC solid-phase extraction (SPE). Microflow LC reverse-phase separation was achieved with a gradient mobile phase of 10mM ammonium acetate pH 6 and acetonitrile over 10 min. We employed a Q Exactive high resolution mass spectrometer, with compounds identified and quantified by targeted-MSMS experiments. The assay was linear 0.5–50 ng/mL for THC, CBD and CBN, and 15–500 pg/mL for THCCOOH. Intra- and inter-day and total imprecision were <10.8%CV and bias 86.5–104.9%. Extraction efficiency was 52.4–109.2%, process efficiency 12.2– 88.9% and matrix effect ranged from ?86 to ?6.9%. All analytes were stable for 24h at 5°C on the autosampler. The method was applied to authentic OF specimens collected with Quantisal and Oral-Eze devices. This method provides a rapid simultaneous quantification of THCCOOH and THC, CBD, CBN, with good selectivity and sensitivity, providing the opportunity to improve interpretation of cannabinoid OF results by eliminating the possibility of passive inhalation and providing markers of recent cannabis smoking. PMID:23726246

Concheiro, Marta; Lee, Dayong; Lendoiro, Elena; Huestis, Marilyn A.

2014-01-01

266

:investigation of a 24-inch Shock-in-rotor Type Supersonic Compressor Designed for Simple Radial Equilibrium Behind Normal Shock  

NASA Technical Reports Server (NTRS)

A 24-inch-diameter shock-in-rotor supersonic compressor rotor designed to obtain simple radial equilibrium behind the normal shock obtained a maximum total-pressure ratio of 2.02 at an adiabatic efficiency of 0.74 and a weight flow of 61.5 pounds per second at design speed. Although this design method considerably reduced the radial forces, there was no apparent reduction in the radial forces, there was no apparent reduction in the radial redistribution of mass flow over the radial redistribution obtained in the previous investigation. This investigation indicates that the shock boundary-layer interaction pattern and associated effects have a very large effect on the radial redistribution of mass flow through the shock-in-rotor supersonic-compressor rotor.

Lown, Harold; Hartmann, Melvin J

1951-01-01

267

Severity grading in radial dysplasia.  

PubMed

A functional scoring method to grade the usefulness and quality of the upper limbs in congenital radial dysplasia is presented. It is based on the author's examinations of 44 arms with congenital deficiency of the radius. The hand (H), wrist (W) and proximal parts (P) of the extremity are each scored from 0 to 10 points for severity. The scoring is expressed similarly to the TNM (tumour, nodes, metastasis) tumour classification, for example as H5W4P2. The maximum severity index is 30 points. A severity grade of mild is between 1 and 8 points, moderate between 9 and 16 points and severe 17 points and over. In the author's series, the grades were mild in eight, moderate in 21 and severe in 15 cases. The functional severity grading should allow better comparison of radially deficient limbs and the results of treatment between groups of patients. PMID:24401744

Vilkki, S K

2014-11-01

268

Radial Reflection Diffraction Tomography Notes  

SciTech Connect

We are developing the theory behind a new imaging modality which uses a single transducer rotating about its center to launch a field radially outward and collect the backscattered (reflected) field. We use diffraction tomography techniques, based upon a linearized version of the field scattering equation, to form images of the medium surrounding the transducer. As there is one transducer which both transmits the incident field and measures the backscattered field, the operation mode is multimonostatic.

Lehman, S K; Norton, S J

2002-06-27

269

Flow-through dispersed carbon nanofiber-based microsolid-phase extraction coupled to liquid chromatography for automatic determination of trace levels of priority environmental pollutants.  

PubMed

Handling of carbon nanoparticles as sorptive materials in a flow-through packed-bed mode has been to date hampered by undue pressure drop and deteriorated retention efficiency because of nanoparticle bundling and entanglement. To surmount this limitation, a dedicated stirred-flow sorptive microchamber integrated in a fully automated sequential injection (SI) assembly is herein proposed for expedient handling and reuse of carbon nanoparticles in microsolid-phase extraction (?SPE) procedures. The assembled setup features automatic uptake, preconcentration, and retrieval of target organic species using dispersed nanoparticles as a front-end to liquid chromatographic (LC) assays. Chlorotriazine residues (atrazine, simazine, and propazine) and dealkylated metabolites thereof (deisopropyltriazine (DIA) and deethylatrazine (DEA)) were selected as model compounds because of their electron-poor aromatic structure and potentially strong ?-? interactions with electron-rich sorptive materials. The effect of several parameters on the analytical performance including the type and amount of nanoparticles (carbon nanofibers (CNFs), multiwalled carbon nanotubes (MWCNTs) and oxidized carbon nanotubes (MWCNT-COOH), the sample volume (breakthrough volume), the nature and volume of eluent, and the interface between the sample processing module and LC was explored in detail. Using dispersed CNFs at-line coupled to LC, absolute recovery percentages for 10 mL sample percolation were >94% for the overall herbicides with enrichment factors of ca. 20, limits of detection (S/N = 3) of 0.004-0.03 ng mL(-1), limits of quantification (S/N = 10) of 0.01-0.09 ng mL(-1) and repeatability within the range 0.5-1.8%. The SI-CNF-LC hyphenated system was harnessed to the analysis of not merely untreated environmental waters at concentration levels below those endorsed by the current EU Water Framework Directives but to crude soil extracts for which CNF reuse with no loss of retention efficiency was proven feasible by resorting to appropriate automatic regeneration procedures and internal standardization. PMID:21553915

Boonjob, Warunya; Miró, Manuel; Segundo, Marcela A; Cerdà, Víctor

2011-07-01

270

Separation and quantification of 238U, 232Th and rare earths in monazite samples by ion chromatography coupled with on-line flow scintillation detector.  

PubMed

An alternative procedure has been described for efficient separation and quantitative determination of uranium (U), thorium (Th) and rare earth elements (REEs) in monazite mineral by high performance ion chromatographic system (IC). Different variables affecting the distribution coefficient, the retention and hence separation efficiency such as eluent flow rate and concentrations of HCI and ammonium sulfate (NH4)2SO4 containing the mobile phase were studied. The developed separation protocol of U, Th and REEs was optimized using an Ion Pac CS5 separation column followed by post-column derivatization reaction with Arsenaso III and UV-VIS spectrophotometric detection. Comparative evaluation of U, Th and REEs concentration in monazite mineral was demonstrated using two different on-line detection modes including flow through cell scintillation detector (FSD) and UV-VIS spectrophotometer. Response of the FSD was found to be linear over the full range of activities investigated (4-100 Bq). The lower limits of detection (LLD) for the investigated radionuclides were 3.0+0.1 Bq for 238U and 6.0 +/- 0.1 Bq for 232Th. The detection of 238U and 232Th by FSD shows good agreement with the corresponding determination by UV-VIS spectrophotometer. The content of ThO2 and U3O8 in monazite sample were found to be 4.7 +/- 0.1% and 0.42 +/- 0.04% using UV-VIS detector and 4.3 +/- 0.1% and 0.45 +/- 0.1% using FSD, respectively. PMID:12361323

Borai, E H; Mady, A S

2002-10-01

271

Property of radially quadratic reflector systems  

NASA Technical Reports Server (NTRS)

This report shows that when considered in terms of optical geometry, radially parabolic and radially hyperbolic mirrors used as mirrors for Cassegrain and parabolic antennas possess values similar to common conical horn reflector antennas.

Mizusawa, M.; Katagi, T.

1986-01-01

272

RADIAL STELLAR PULSATION AND THREE-DIMENSIONAL CONVECTION. II. TWO-DIMENSIONAL CONVECTION IN FULL AMPLITUDE RADIAL PULSATION  

SciTech Connect

We have developed a three-dimensional radiation hydrodynamics code to simulate the interaction of convection and radial pulsation in classical variable stars. One key goal is the ability to carry these simulations to full amplitude in order to compare them with observed light curves. Previous multi-dimensional calculations were prevented from reaching full amplitude because of drift in the radial coordinate system, due to the algorithm defining radial movement of the coordinate system during the pulsation cycle. We have removed this difficulty by defining our radial coordinate flow algorithm to require that the mass in a spherical shell remain constant for every time step throughout the pulsation cycle. We have used our new code to perform two-dimensional (2D) simulations of the interaction of radial pulsation and convection. We have made comparisons between light curves from our 2D convective simulations with observed light curves and find that our 2D simulated light curves are better able to match the observed light curve shape near the red edge of the RR Lyrae instability strip than light curves from previous one-dimensional time-dependent convective models.

Geroux, Chris M.; Deupree, Robert G., E-mail: geroux@astro.ex.ac.uk [Institute for Computational Astrophysics and Department of Astronomy and Physics, Saint Mary's University, Halifax, NS B3H 3C3 (Canada)

2013-07-10

273

Chromatography resin support  

DOEpatents

An apparatus and method of using an improved chromatography resin support is disclosed. The chromatography support platform is provided by a stainless steel hollow cylinder adapted for being inserted into a chromatography column. An exterior wall of the stainless steel cylinder defines a groove for carrying therein an "O"-ring. The upper surface of the stainless steel column is covered by a fine stainless steel mesh welded to the edges of the stainless steel cylinder. When placed upon a receiving ledge defined within a chromatography column, the "O"-ring provides a fluid tight seal with the inner edge wall of the chromatography cylinder. The stainless steel mesh supports the chromatography matrix and provides a back flushable support which is economical and simple to construct.

Dobos, James G. (North Augusta, SC)

2002-01-01

274

Automated and sensitive determination of four anabolic androgenic steroids in urine by online turbulent flow solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry: a novel approach for clinical monitoring and doping control.  

PubMed

A novel method for automated and sensitive analysis of testosterone, androstenedione, methyltestosterone and methenolone in urine samples by online turbulent flow solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry was developed. The optimization and validation of the method were discussed in detail. The Turboflow C18-P SPE column showed the best extraction efficiency for all the analytes. Nanogram per liter (ng/L) level of AAS could be determined directly and the limits of quantification (LOQs) were 0.01 ng/mL, which were much lower than normally concerned concentrations for these typical anabolic androgenic steroids (AAS) (0.1 ng/mL). The linearity range was from the LOQ to 100 ng/mL for each compound, with the coefficients of determination (r(2)) ranging from 0.9990 to 0.9999. The intraday and interday relative standard deviations (RSDs) ranged from 1.1% to 14.5% (n=5). The proposed method was successfully applied to the analysis of urine samples collected from 24 male athletes and 15 patients of prostate cancer. The proposed method provides an alternative practical way to rapidly determine AAS in urine samples, especially for clinical monitoring and doping control. PMID:24840468

Guo, Feng; Shao, Jing; Liu, Qian; Shi, Jian-Bo; Jiang, Gui-Bin

2014-07-01

275

Evaluation of interactions between metal ions and nonionic surfactants in high-concentration HCl using low-pressure high-performance liquid chromatography with low-flow-resistance polystyrene-based monolithic column.  

PubMed

A method for evaluating the interactions between metal ions and nonionic surfactants in aqueous solutions containing high-concentration HCl, using gas pressure-driven low-pressure high-performance liquid chromatography (LP-HPLC) as a highly acid-resistant HPLC system, was developed. To construct the LP-HPLC for this purpose, poly(styrene-co-divinylbenzene)-based low-flow-resistance monolithic columns tolerant to highly acidic conditions were prepared using low-conversion thermal polymerization. Thermal polymerization at 65 °C for 1.5 h (monomer conversions, 33% for styrene and 59% for divinylbenzene) allowed preparation of a column with both high separation efficiency (around 60,000 plates m(-1) for alkylbenzenes) and a quite low back pressure of 0.14 MPa at a linear flow rate of 1 mm s(-1) (2.8 × 10(-13) m(2) in permeability). The base column prepared under the above conditions was coated with a nonionic surfactant, polyoxyethylene nonylphenyl ether (PONPE, average oxyethylene unit numbers (n) = 3, 7.5, 15, and 20), and used for evaluation of the interactions between PONPEs and metal ions in 6 M HCl. The interactions between PONPEs and Au(III), Ga(III), Fe(III), Zn(II), and Cu(II) were successfully evaluated using both breakthrough and chromatographic methods. Furthermore, a study of the effect of the polyoxyethylene (POE) chain length revealed that the use of PONPE with the longer POE moiety enhanced the magnitude of the interaction together with the increase in the amount of oxyethylene (OE) units coated on the monolith. Moreover, the interactions of metal ions with a single OE unit were almost constant in the range of n = 7.5-20, whereas the suppression of the interaction between Au(III) with the shortest PONPE chain (n = 3) was also observed. PMID:23884474

Hirano, Tomohiko; Kitagawa, Shinya; Ohtani, Hajime; Kinoshita, Takehiko; Ishigaki, Yuzo; Shibata, Nobuyuki; Nii, Susumu

2013-10-01

276

Fun with Paper Chromatography.  

ERIC Educational Resources Information Center

Discusses paper chromatographic techniques and provides examples of typical classroom activities. Includes description of retardation values obtained during chromatography exercises and suggests using them for math lessons. (JN)

Coleman, Dava; Hounshell, Paul B.

1982-01-01

277

Fluctuating Pressure Environments and Hydrodynamic Radial Force Mitigation for a Two Blade Unshrouded Inducer  

NASA Technical Reports Server (NTRS)

Fluctuating pressure data from water flow testing of an unshrouded two blade inducer revealed a cavitation induced oscillation with the potential to induce a radial load on the turbopump shaft in addition to other more traditionally analyzed radial loads. Subsequent water flow testing of the inducer with a rotating force measurement system confirmed that the cavitation induced oscillation did impart a radial load to the inducer. After quantifying the load in a baseline configuration, two inducer shroud treatments were selected and tested to reduce the cavitation induced load. The first treatment was to increase the tip clearance, and the second was to introduce a circumferential groove near the inducer leading edge. Increasing the clearance resulted in a small decrease in radial load along with some steady performance degradation. The groove greatly reduced the hydrodynamic load with little to no steady performance loss. The groove did however generate some new, relatively high frequency, spatially complex oscillations to the flow environment.

Mulder, Andrew; Skelley, Stephen

2011-01-01

278

Radial segregation in VGF-RMF grown germanium  

NASA Astrophysics Data System (ADS)

In this paper experimental results of the radial dopant segregation in Ge:Ga single crystals grown by the vertical gradient freeze technique with a rotating magnetic field are presented. The segregation is analysed on the basis of the carrier concentration measured by means of Hall effect and Fourier transform infrared (FTIR) spectroscopy. In growth without the field the carrier concentration increases towards the axis, whereas much more uniform radial concentration profiles are found in crystals grown under the influence of the rotating field indicating a pronounced impact of the melt flow on the dopant segregation. Apparently, the accumulation of the Ga solute near the centre of the melt during growth under natural buoyancy is reduced by the electromagnetically induced flow. This phenomenon is discussed with respect to analytical and numerical results published recently.

Bellmann, M. P.; Pätzold, O.; Gärtner, G.; Möller, H. J.; Stelter, M.

2009-03-01

279

Should the radial artery be used as a bypass graft following radial access coronary angiography.  

PubMed

The radial artery (RA) is often selected as the next conduit of choice following the internal thoracic artery for coronary artery bypass grafting operations (CABG). Radial access coronary angiography (RA-CA) has grown in popularity among cardiologists and has been advocated as the access route of choice for coronary angiography and intervention by many groups. However, sheath insertion and instrumentation may lead to structural and functional damage to the RA, which may preclude its use as a bypass conduit. The increasing use of RA-CA may therefore have an adverse effect on the ability to use the RA as a bypass conduit at subsequent CABG. To review this, a best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was: 'should the radial artery be used as a bypass conduit following radial access coronary angiography'? Altogether, 167 papers were found using the reported search; 11 papers were identified that provided the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these studies were tabulated. Acute RA occlusion occurs in 2.3-30.5% of patients undergoing RA-CA. While a significant number of occluded RA's show recanalization on early follow-up, markers of endothelial function such as intima-media thickening (IMT) and flow-mediated dilatation remain impaired. RA-CA causes structural injury to the RA with evidence of histological injury (including intimal hyperplasia, periarterial tissue/fat necrosis and adventitial inflammation) along with intimal tears and medial dissections evident along the entire length of the vessel. Only one paper directly assesses patency rates of RA's used as bypass grafts following RA-CA finding a significant adverse effect on graft patency (77% patency in RA-CA, compared with 98% in the control group). We recommend avoiding the RA as a bypass conduit if it has previously been used for RA-CA. In situations where conduit options are limited, if possible, the RA should be avoided for at least 3 months following RA-CA and it may be beneficial to assess the RA's patency and flow characteristics with Doppler ultrasound preoperatively. PMID:24254539

Lim, Lisa M; Galvin, Sean D; Javid, Mohamed; Matalanis, George

2014-02-01

280

Radial-Electric-Field Piezoelectric Diaphragm Pumps  

NASA Technical Reports Server (NTRS)

In a recently invented class of piezoelectric diaphragm pumps, the electrode patterns on the piezoelectric diaphragms are configured so that the electric fields in the diaphragms have symmetrical radial (along-the-surface) components in addition to through-the-thickness components. Previously, it was accepted in the piezoelectric-transducer art that in order to produce the out-of-plane bending displacement of a diaphragm needed for pumping, one must make the electric field asymmetrical through the thickness, typically by means of electrodes placed on only one side of the piezoelectric material. In the present invention, electrodes are placed on both sides and patterned so as to produce substantial radial as well as through-the-thickness components. Moreover, unlike in the prior art, the electric field can be symmetrical through the thickness. Tests have shown in a given diaphragm that an electrode configuration according to this invention produces more displacement than does a conventional one-sided electrode pattern. The invention admits of numerous variations characterized by various degrees of complexity. Figure 1 is a simplified depiction of a basic version. As in other piezoelectric diaphragm pumps of similar basic design, the prime mover is a piezoelectric diaphragm. Application of a suitable voltage to the electrodes on the diaphragm causes it to undergo out-of-plane bending. The bending displacement pushes a fluid out of, or pulls the fluid into, a chamber bounded partly by the diaphragm. Also as in other diaphragm pumps in general, check valves ensure that the fluid flows only in through one port and only out through another port.

Bryant, Robert G.; Working, Dennis C.; Mossi, Karla; Castro, Nicholas D.; Mane, Pooma

2009-01-01

281

Kool-Aid Chromatography  

ERIC Educational Resources Information Center

Offers guidelines and suggests activities that can introduce middle school students to the process and principles of chromatography in an inexpensive and safe manner. Proposes that experiences with Kool-aid and food coloring chromatography can provide insights into how scientists think, work, and communicate. (ML)

Jenkins, Christie L.

1986-01-01

282

Advanced proteomic liquid chromatography  

SciTech Connect

Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput.

Xie, Fang; Smith, Richard D.; Shen, Yufeng

2012-10-26

283

Liquid Chromatography in 1982.  

ERIC Educational Resources Information Center

Reviews trends in liquid chromatography including apparatus, factors affecting efficient separation of a mixture (peak sharpness and speed), simplified problem-solving, adsorption, bonded phase chromatography, ion selectivity, and size exclusion. The current trend is to control chemical selectivity by the liquid phase. (Author/JN)

Freeman, David H.

1982-01-01

284

Cavity Ring-Down Spectroscopy as a Detector for Liquid Chromatography  

E-print Network

Cavity Ring-Down Spectroscopy as a Detector for Liquid Chromatography Kate L. Snyder and Richard N chromatography (HPLC). For this use, we have designed and implemented a Brewster's angle flow cell UV-vis absorption detector for the same path length. High performance liquid chromatography (HPLC

Zare, Richard N.

285

Radial Alignment in Simulated Clusters  

E-print Network

Observational evidence for the radial alignment of satellites with their dark matter host has been accumulating steadily in the past few years. The effect is seen over a wide range of scales, from massive clusters of galaxies down to galaxy-sized systems, yet the underlying physical mechanism has still not been established. To this end, we have carried out a detailed analysis of the shapes and orientations of dark matter substructures in high-resolution N-body cosmological simulations. We find a strong tendency for radial alignment of the substructure with its host halo: the distribution of halo major axes is very anisotropic, with the majority pointing towards the center of mass of the host. The alignment peaks once the sub-halo has passed the virial radius of the host for the first time, but is not subsequently diluted, even after the halos have gone through as many as four pericentric passages. This evidence points to the existence of a very rapid dynamical mechanism acting on these systems and we argue that tidal torquing throughout their orbits is the most likely candidate.

Maria J. Pereira; Greg L. Bryan; Stuart P. D. Gill

2007-07-12

286

Analyses of hydrodynamic radial forces on centrifugal pump impellers  

NASA Technical Reports Server (NTRS)

An experimental and theoretical study of the hydrodynamic interactions occurring between a centrifugal pump impeller and a volute is presented. The theoretical analysis provides a quasi-one-dimensional treatment of the flow in the volute, and it is extended to include the hydrodynamic force perturbations caused by the impeller whirling eccentrically in the volute. It is noted that these perturbations are often destabilizing. The theoretical models were found to accurately predict the radial forces caused by the flow through the impeller. The pressure acting on the front shroud of the impeller is shown to have a significant effect on the destabilizing hydrodyamic forces.

Adkins, D. R.; Brennen, C. E.

1988-01-01

287

Liquid-phase chromatography detector  

DOEpatents

A liquid-phase chromatography detector comprising a flow cell having an inlet tubular conduit for receiving a liquid chromatographic effluent and discharging it as a flowing columnar stream onto a vertically adjustable receiving surface spaced apart from and located vertically below and in close proximity to the discharge end of the tubular conduit; a receiver adapted to receive liquid overflowing from the receiving surface; an exit conduit for continuously removing liquid from the receiver; a light source for focussing fluorescence-producing light pulses on the flowing columnar stream as it passes from the outlet of the conduit to the receiving surface and a fluorescence detector to detect the produced fluorescence; a source of light pulse for producing acoustic waves in the columnar stream as it passes from the conduit outlet to the receiving surface; and a piezoelectric transducer adapted to detect those waves; and a source of bias voltage applied to the inlet tubular conduit and adapted to produce ionization of the liquid flowing through the flow cell so as to produce photocurrents therein and an electrical system to detect and record the photocurrents. This system is useful in separating and detecting individual chemical compounds from mixtures thereof.

Voigtman, Edward G. (Gainesville, FL); Winefordner, James D. (Gainesville, FL); Jurgensen, Arthur R. (Gainesville, FL)

1983-01-01

288

Liquid-phase chromatography detector  

DOEpatents

A liquid-phase chromatography detector comprises a flow cell having an inlet tubular conduit for receiving a liquid chromatographic effluent and discharging it as a flowing columnar stream onto a vertically adjustable receiving surface spaced apart from and located vertically below and in close proximity to the discharge end of the tubular conduit; a receiver adapted to receive liquid overflowing from the receiving surface; an exit conduit for continuously removing liquid from the receiver; a light source for focusing fluorescence-producing light pulses on the flowing columnar stream as it passes from the outlet of the conduit to the receiving surface and a fluorescence detector to detect the produced fluorescence; a source of light pulse for producing acoustic waves in the columnar stream as it passes from the conduit outlet to the receiving surface; and a piezoelectric transducer adapted to detect those waves; and a source of bias voltage applied to the inlet tubular conduit and adapted to produce ionization of the liquid flowing through the flow cell so as to produce photocurrents therein and an electrical system to detect and record the photocurrents. This system is useful in separating and detecting individual chemical compounds from mixtures thereof. 5 figs.

Voigtman, E.G.; Winefordner, J.D.; Jurgensen, A.R.

1983-11-08

289

Journal of Chromatography B, 902 (2012) 7883 Contents lists available at SciVerse ScienceDirect  

E-print Network

Journal of Chromatography B, 902 (2012) 78­83 Contents lists available at SciVerse ScienceDirect Journal of Chromatography B journal homepage: www.elsevier.com/locate/chromb Diffusion Split-Flow Thin

Utah, University of

290

Numerical modeling of the elution peak profiles of retained solutes in supercritical fluid chromatography  

SciTech Connect

In supercritical fluid chromatography (SFC), the significant expansion of the mobile phase along the column causes the formation of axial and radial gradients of temperature. Due to these gradients, the mobile phase density, its viscosity, its velocity, its diffusion coefficients, etc. are not constant throughout the column. This results in a nonuniform flow velocity distribution, itself causing a loss of column efficiency in certain cases, even at low flow rates, as they do in HPLC. At high flow rates, an important deformation of the elution profiles of the sample components may occur. The model previously used to account satisfactorily for the retention of an unsorbed solute in SFC is applied to the modeling of the elution peak profiles of retained compounds. The numerical solution of the combined heat and mass balance equations provides the temperature and the pressure profiles inside the column and values of the retention time and the band profiles of retained compounds that are in excellent agreement with independent experimental data for large value of mobile phase reduced density. At low reduced densities, the band profiles can strongly depend on the column axial distribution of porosity.

Kaczmarski, Krzysztof [University of Tennessee and Rzeszow University of Technology, Poland; Guiochon, Georges A [ORNL

2011-01-01

291

Flat disc, radially nonhomogeneous, lenses  

NASA Astrophysics Data System (ADS)

A plane surfaced lens can be constructed through the use of a radially nonhomogenous medium, with axial symmetry. The rays from an axial source are incident on the plane front surface, perpendicular to the axis, where the assumption is made that the rays obey Snell's laws locally as for an infinite uniform medium. The curved ray paths are then given by the standard ray integral and are taken up to the point where each ray becomes horizontal. For certain polynomial functions describing the refractive index, the ray integral is an incomplete elliptic integral of the first kind, and trial functions can be inserted, such that the rays have become horizontal all at a second plane surface, thus creating a flat disk lens. The total symmetry of the design provides for many advantageous properties.

Cornbleet, S.

1980-12-01

292

A variational principle and its implications for radial electric field and rotation in tokamaks  

NASA Astrophysics Data System (ADS)

A variational principle that minimizes an energy functional of the total electric field and the kinetic energy of the plasma flows with respect to the radial electric field is presented. Minimization is performed order by order in a small-gyroradius expansion, retaining up to second-order electric fields and third-order flows in the small parameter δ = ρi/L. The electric fields and flows obtained variationally are interpreted in the context of a global momentum conservation integral, while comparing them with neoclassical results based on the radial transport of toroidal angular momentum.

Aydemir, A. Y.; Kim, J. Y.; Park, B. H.

2014-10-01

293

A fully relativistic radial fall  

E-print Network

Radial fall has historically played a momentous role. It is one of the most classical problems, the solutions of which represent the level of understanding of gravitation in a given epoch. A {\\it gedankenexperiment} in a modern frame is given by a small body, like a compact star or a solar mass black hole, captured by a supermassive black hole. The mass of the small body itself and the emission of gravitational radiation cause the departure from the geodesic path due to the back-action, that is the self-force. For radial fall, as any other non-adiabatic motion, the instantaneous identity of the radiated energy and the loss of orbital energy cannot be imposed and provide the perturbed trajectory. In the first part of this letter, we present the effects due to the self-force computed on the geodesic trajectory in the background field. Compared to the latter trajectory, in the Regge-Wheeler, harmonic and all others smoothly related gauges, a far observer concludes that the self-force pushes inward (not outward) the falling body, with a strength proportional to the mass of the small body for a given large mass; further, the same observer notes an higher value of the maximal coordinate velocity, this value being reached earlier on during infall. In the second part of this letter, we implement a self-consistent approach for which the trajectory is iteratively corrected by the self-force, this time computed on osculating geodesics. Finally, we compare the motion driven by the self-force without and with self-consistent orbital evolution. Subtle differences are noticeable, even if self-force effects have hardly the time to accumulate in such a short orbit.

Alessandro D. A. M. Spallicci; Patxi Ritter

2014-07-21

294

Design and Numerical Investigation of Advanced Radial Inlet for a Centrifugal Compressor Stage  

Microsoft Academic Search

The performance of a centrifugal compressor stage can be seriously affected by inlet flow distortions due to an unsatisfactory inlet configuration and the resulting flow structure. In this study, two radial inlets were designed for a centrifugal compressor stage and investigated numerically using a commercially available 3D viscous Navier-Stokes code. The intent of the design was to minimize the total

Yunbae Kim; Jay Koch

295

Large radial graded-index polymer  

NASA Astrophysics Data System (ADS)

A very large radial graded-index (GRIN) polymer was successfully prepared for the first time, to curved mold method and the diffusion copolymerization method. Both methods gave a radial GRIN polymer with a diameter of 70 mm and a Delta n value greater than 0.02. Ray tracing through these radial GRIN polymers was used to predict that such a GRIN polymer could be a promising candidate for thinner ophthalmic lenses with no spherical aberration or multifocusing characteristics.

Wu, Shang Pin; Nihei, Eisuke; Koike, Yasuhiro

1996-01-01

296

Two stages of visual processing for radial and circular motion  

NASA Astrophysics Data System (ADS)

As we move through our environment, the flow of the deforming images on our retinae provides rich information about ego motion and about the three-dimensional structure of the external world. Flow-fields comprise five independent compenents, including radial and circular motion1á¤-3. Here we provide psychophysical evidence for the existence of neural mechanisms in human vision that integrate motion signals along these complex trajectories. Signal-to-noise sensitivity for discriminating the direction of radial, circular and translational motion increased predictably with the number of exposed sectors, implying the existence of specialized detectors that integrate motion signals of different directions from different locations. However, contrast sensitivity for complex motion did not increase greatly with sector number, implying that the specialized detectors are preceded by a first stage of local-motion mechanisms that impose a contrast threshold. These findings fit well with recent electrophysiological evidence in monkey4á¤-7 showing that whereas motion-sensitive neurons in primary visual cortex respond best to local translation, many neurons in the medial superior temporal cortex have large receptive fields tuned to radial, circular or spiral motion.

Morrone, M. C.; Burr, David C.; Vaina, Lucia M.

1995-08-01

297

Radial forces in a centrifugal compressor; Experimental investigation by using magnetic bearings and static pressure distribution  

NASA Astrophysics Data System (ADS)

The volute of a centrifugal compressor causes a non-uniform pressure distribution which leads to a radial force on the impeller. This force was measured using magnetic bearings. In addition, the radial force was estimated using the static pressure distribution measured at the impeller outlet. The impeller force was found to be the highest at choke, the lowest at the design flow and moderate at stall. The radial force determined from the pressure measurements was only slightly different from the force obtained from the bearing measurements. The rotational speed was seen to affect the force to some extent.

Reunanen, Arttu; Larjola, Jaakko

2005-03-01

298

Effect of radial inflow on vortex intensification for a tornado-type wind turbine  

SciTech Connect

A new wind vortex turbine, called tornado-type wind turbine, was studied both theoretically and experimentally for the purpose of better understanding the basic nature of a vortex flow and further improvement of its power efficiencies. Analytical solutions were obtained from the Navier-Stokes equations for the velocity distributions along the radial distance. The result demonstrates the important nature of a vortex structure that, in order to intensify a vortex inside the tower, radial inflow must be provided from the side walls. Based upon this concept, the essential contribution of our experimental work was to furnish the radial inflow by utilizing the dynamic head of incoming wind.

Hsu, C.T.; Ide, H.

1982-09-01

299

Aerodynamically induced radial forces in a centrifugal gas compressor: Part 2 -- Computational investigation  

Microsoft Academic Search

Radial loads and direction of a centrifugal gas compressor containing a high specific speed mixed flow impeller and a single tongue volute were determined both experimentally and computationally at both design and off-design conditions. The experimental methodology was developed in conjunction with a traditional ASME PTC-10 closed-loop test to determine radial load and direction. The experimental study is detailed in

M. B. Flathers; G. E. Bache?

1999-01-01

300

Basic Liquid Chromatography  

NSDL National Science Digital Library

This online textbook offers a variety of information on high performance liquid chromatography (HPLC). Topics covered include instruments, detectors, theory, column selection, and pH effect. This website also contains links to a glossary, useful links, and manufacturer websites.

Kazakevich, Yuri; Mcnair, Harold; Chemistry, Seton H.

301

Fabrication of cooled radial turbine rotor  

NASA Technical Reports Server (NTRS)

A design and fabrication program was conducted to evaluate a unique concept for constructing a cooled, high temperature radial turbine rotor. This concept, called split blade fabrication was developed as an alternative to internal ceramic coring. In this technique, the internal cooling cavity is created without flow dividers or any other detail by a solid (and therefore stronger) ceramic plate which can be more firmly anchored within the casting shell mold than can conventional detailed ceramic cores. Casting is conducted in the conventional manner, except that the finished product, instead of having finished internal cooling passages, is now a split blade. The internal details of the blade are created separately together with a carrier sheet. The inserts are superalloy. Both are produced by essentially the same software such that they are a net fit. The carrier assemblies are loaded into the split blade and the edges sealed by welding. The entire wheel is Hot Isostatic Pressed (HIPed), braze bonding the internal details to the inside of the blades. During this program, two wheels were successfully produced by the split blade fabrication technique.

Hammer, A. N.; Aigret, G. G.; Psichogios, T. P.; Rodgers, C.

1986-01-01

302

Gas chromatography in space  

NASA Technical Reports Server (NTRS)

Gas chromatography has proven to be a very useful analytical technique for in situ analysis of extraterrestrial environments as demonstrated by its successful operation on spacecraft missions to Mars and Venus. The technique is also one of the six scientific instruments aboard the Huygens probe to explore Titan's atmosphere and surface. A review of gas chromatography in previous space missions and some recent developments in the current environment of fiscal constraints and payload size limitations are presented.

Akapo, S. O.; Dimandja, J. M.; Kojiro, D. R.; Valentin, J. R.; Carle, G. C.

1999-01-01

303

Chromatography Nomenclature and Definitions  

NSDL National Science Digital Library

This website gives the International Union of Pure and Applied Chemistry approved definitions in the field of chromatography. It is critical for students to appreciate the importance of using standardized nomenclature and definitions. Sections of the site include general terminology, terms related to the chromatographic system, terms related to the chromatographic process and the theory of chromatography, terms related to detection, ion exchange, liquid-liquid distribution (solvent extraction) and other related subjects.

2011-05-12

304

Basic Liquid Chromatography  

NSDL National Science Digital Library

The online textbook, Basic Liquid Chromatography, is provided by Dr. Yuri Kazakevich and Dr. Harold McNair of Seton Hall University. For those needing review or an introduction to the subject, the well designed and easily read document contains a wealth of information. Sections include an introduction, instrumentation, detectors, theory, adsorbents, reversed phase, gel permeation chromatography, column selection, pH effect, and even an online short course.

Kazakevich, Yuri.; McNair, Harold Monroe, 1933-.

1996-01-01

305

Advanced proteomic liquid chromatography  

PubMed Central

Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput. PMID:22840822

Xie, Fang; Smith, Richard D.; Shen, Yufeng

2012-01-01

306

Experimental evaluation of a translating nozzle sidewall radial turbine  

NASA Technical Reports Server (NTRS)

An experimental performance evaluation was made of two movable sidewall variable area radial turbines. The turbine designs were representative of the gas generator turbine of a variable flow capacity rotorcraft engine. The first turbine was an uncooled design while the second turbine had a cooled nozzle but an uncooled rotor. The cooled nozzle turbine was evaluated both with and without coolant flow. The test results showed that the movable nozzle wall is a viable and efficient means to effectively control the flow capacity of a radial turbine. Peak efficiencies of the second turbine with and without nozzle coolant were 86.5 and 88 percent respectively. These values are comparable to pivoting vane variable geometry turbines; however, the decrease in efficiency as the flow was varied from the design value was much less for the movable wall turbine. Several design improvements which should increase the turbine efficiency one or two more points are identified. These design improvements include reduced leakage losses and relocation of the vane coolant ejection holes to reduce mainstream disturbance.

Roelke, Richard J.; Rogo, Casimir

1987-01-01

307

Radial keratotomy associated endothelial degeneration  

PubMed Central

Purpose To describe the presentation and clinical course of eyes with a history of radial keratotomy (RK) and varying degrees of endothelial degeneration. Methods Retrospective case series were used. Results Thirteen eyes (seven patients) were identified with clinical findings of significant guttata and a prior history of RK. The mean age of presentation for cornea evaluation was 54.3 years (range: 38–72 years), averaging 18.7 years (range: 11–33 years) after RK. The presentation of guttata varied in degree from moderate to severe. Best corrected visual acuity (BCVA) ranged from 20/25 to 20/80. All patients had a history of bilateral RK, except one patient who did not develop any guttata in the eye without prior RK. No patients reported a family history of Fuch’s Dystrophy. One patient underwent a penetrating keratoplasty in one eye and a Descemet’s stripping automated endothelial keratoplasty (DSAEK) in the other eye. Conclusions RK may induce a spectrum of endothelial degeneration. In elderly patients, the findings of guttata may signify comorbid Fuch’s dystrophy in which RK incisions could potentially hasten endothelial decomposition. In these select patients with stable cornea topography and prior RK, DSAEK may successfully treat RK endothelial degeneration. PMID:22347792

Moshirfar, Majid; Ollerton, Andrew; Semnani, Rodmehr T; Hsu, Maylon

2012-01-01

308

Radial force in a bearingless reluctance motor  

Microsoft Academic Search

A four-pole reluctance synchronous machine with additional two-pole windings was constructed. The additional winding currents produce the radial force to act as a magnetic bearing. Expressions for the machine inductance functions are given. Inductance functions with respect to the eccentric displacement of the rotor were measured. The contribution of these inductances to the radial force production is established

Akira Chiba; M. Azizur Rahman; Tadashi Fukao

1991-01-01

309

Combination radial and thrust magnetic bearing  

NASA Technical Reports Server (NTRS)

A combination radial and thrust magnetic bearing is disclosed that allows for both radial and thrust axes control of an associated shaft. The combination radial and thrust magnetic bearing comprises a rotor and a stator. The rotor comprises a shaft, and first and second rotor pairs each having respective rotor elements. The stator comprises first and second stator elements and a magnet-sensor disk. In one embodiment, each stator element has a plurality of split-poles and a corresponding plurality of radial force coils and, in another embodiment, each stator element does not require thrust force coils, and radial force coils are replaced by double the plurality of coils serving as an outer member of each split-pole half.

Blumenstock, Kenneth A. (Inventor)

2002-01-01

310

Summary We monitored the radial distribution of sap flux density (v; g H2O m2  

E-print Network

of the stem (i.e., radial profile) was Gaussian in shape. Sap flow oc- curred maximally in the outer 4 cm: canopy conductance, capacitance, sap flow, tem- poral variability, time series analysis, transpiration in temporally scal- ing whole-stem basal sap flow to canopy transpiration because of time lags arising from

Teskey, Robert O.

311

Laminar mixed convection in a radially rotating semiporous channel  

NASA Astrophysics Data System (ADS)

Flow and heat transfer characteristics of laminar mixed convection in a radially rotating semiporous channel with a uniform transpiration and a constant wall temperature gradient are examined. The buoyancy effect is taken into account through the consideration of the density variation in the centrifugal force term. A similarity solution is sought; and then the effects of rotation, transpiration and wall heating on the velocity and temperature fields, the skin friction, the pressure drop and the heat transfer rate are investigated by the solution of the two coupled quasilinear equations. Flow-reversal phenomena can be caused by the transpiration and buoyancy effects. Two modes of flow reversal and the related critical conditions are studied in detail to explore the mechanism of the mixed convection.

Soong, C. Y.; Hwang, G. J.

1990-09-01

312

AUTO-EXPANSIVE FLOW  

EPA Science Inventory

Physics suggests that the interplay of momentum, continuity, and geometry in outward radial flow must produce density and concomitant pressure reductions. In other words, this flow is intrinsically auto-expansive. It has been proposed that this process is the key to understanding...

313

Freeze chromatography method and apparatus  

DOEpatents

A freeze chromatography method and apparatus are provided which enable separation of the solutes contained in a sample. The apparatus includes an annular column construction comprising cylindrical inner and outer surfaces defining an annular passage therebetween. One of the surfaces is heated and the other cooled while passing an eluent through the annular passageway so that the eluent in contact with the cooled surface freezes and forms a frozen eluent layer thereon. A mixture of solutes dissolved in eluent is passed through the annular passageway in contact with the frozen layer so that the sample solutes in the mixture will tend to migrate either toward or away the frozen layer. The rate at which the mixture flows through the annular passageway is controlled so that the distribution of the sample solutes approaches that at equilibrium and thus a separation between the sample solutes occurs. 3 figs.

Scott, C.D.

1987-04-16

314

Effect of blade outlet angle on radial thrust of single-blade centrifugal pump  

NASA Astrophysics Data System (ADS)

Single-blade centrifugal pumps are widely used as sewage pumps. However, a large radial thrust acts on a single blade during pump operation because of the geometrical axial asymmetry of the impeller. This radial thrust causes vibrations of the pump shaft, reducing the service life of bearings and shaft seal devices. Therefore, to ensure pump reliability, it is necessary to quantitatively understand the radial thrust and clarify the behavior and generation mechanism. This study investigated the radial thrust acting on two kinds of single-blade centrifugal impellers having different blade outlet angles by experiments and computational fluid dynamics (CFD) analysis. Furthermore, the radial thrust was modeled by a combination of three components, inertia, momentum, and pressure, by applying an unsteady conservation of momentum to this impeller. As a result, the effects of the blade outlet angle on both the radial thrust and the modeled components were clarified. The total head of the impeller with a blade outlet angle of 16 degrees increases more than the impeller with a blade outlet angle of 8 degrees at a large flow rate. In this case, since the static pressure of the circumference of the impeller increases uniformly, the time-averaged value of the radial thrust of both impellers does not change at every flow rate. On the other hand, since the impeller blade loading becomes large, the fluctuation component of the radial thrust of the impeller with the blade outlet angle of 16 degrees increases. If the blade outlet angle increases, the fluctuation component of the inertia component will increase, but the time-averaged value of the inertia component is located near the origin despite changes in the flow rate. The fluctuation component of the momentum component becomes large at all flow rates. Furthermore, although the time-averaged value of the pressure component is almost constant, the fluctuation component of the pressure component becomes large at a large flow rate. In addition to the increase of the fluctuation component of this pressure component, because the fluctuation component of the inertia and momentum components becomes large (as mentioned above), the radial thrust increases at a large flow rate, as is the case for the impeller with a large blade outlet angle.

Nishi, Y.; Fukutomi, J.; Fujiwara, R.

2012-11-01

315

Building a radial spoke: flagellar radial spoke protein 3 (RSP3) is a dimer.  

PubMed

Radial spokes are critical multisubunit structures required for normal ciliary and eukaryotic flagellar motility. Experimental evidence indicates the radial spokes are mechanochemical transducers that transmit signals from the central pair apparatus to the outer doublet microtubules for local control of dynein activity. Recently, progress has been made in identifying individual components of the radial spoke, yet little is known about how the radial spoke is assembled or how it performs in signal transduction. Here we focus on radial spoke protein 3 (RSP3), a highly conserved AKAP located at the base of the radial spoke stalk and required for radial spoke assembly on the doublet microtubules. Biochemical approaches were taken to further explore the functional role of RSP3 within the radial spoke structure and for control of motility. Chemical crosslinking, native gel electrophoresis, and epitope-tagged RSP3 proteins established that RSP3 forms a dimer. Analysis of truncated RSP3 proteins indicates the dimerization domain coincides with the previously characterized axoneme binding domain in the N-terminus. We propose a model in which each radial spoke structure is built on an RSP3 dimer, and indicating that each radial spoke can potentially localize multiple PKAs or AKAP-binding proteins in position to control dynein activity and flagellar motility. PMID:18157907

Wirschell, Maureen; Zhao, Feifei; Yang, Chun; Yang, Pinfen; Diener, Dennis; Gaillard, Anne; Rosenbaum, Joel L; Sale, Winfield S

2008-03-01

316

Multilayer analytic element modeling of radial collector wells.  

PubMed

A new multilayer approach is presented for the modeling of ground water flow to radial collector wells. The approach allows for the inclusion of all aspects of the unique boundary condition along the lateral arms of a collector well, including skin effect and internal friction losses due to flow in the arms. The hydraulic conductivity may differ between horizontal layers within the aquifer, and vertical anisotropy can be taken into account. The approach is based on the multilayer analytic element method, such that regional flow and local three-dimensional detail may be simulated simultaneously and accurately within one regional model. Horizontal flow inside a layer is computed analytically, while vertical flow is approximated with a standard finite-difference scheme. Results obtained with the proposed approach compare well to results obtained with three-dimensional analytic element solutions for flow in unconfined aquifers. The presented approach may be applied to predict the yield of a collector well in a regional setting and to compute the origin and residence time, and thus the quality, of water pumped by the collector well. As an example, the addition of three lateral arms to a collector well that already has three laterals is investigated. The new arms are added at an elevation of 2 m above the existing laterals. The yield increase of the collector well is computed as a function of the lengths of the three new arms. PMID:16324013

Bakker, Mark; Kelson, Victor A; Luther, Kenneth H

2005-01-01

317

The influence of the radial diffuser geometry on the position of best efficiency point of the multistage pump  

NASA Astrophysics Data System (ADS)

The results of the research which were employed in the systems design of the radial diffuser geometry of the multistage pump with respect to the internal flow pattern especially in the stator are presented in the paper. The contribution deals with the blade cuts shape of the radial diffuser, the course of the diffusion and the suppression of secondary flows in the radial diffuser passages. The areas with secondary flows are investigated on the basis of the CFD simulation. The good image of the influence of some characteristic parameters on the efficiency of the multistage pump with radial diffuser in bulk is obtained by the analysis of velocity and pressure fields in the diffuser.

Varchola, Michal; Hlbo?an, Peter

2014-08-01

318

Radial/axial power divider/combiner  

NASA Technical Reports Server (NTRS)

An electromagnetic power divider/combiner comprises N radial outputs (31) having equal powers and preferably equal phases, and a single axial output (20). A divider structure (1) and a preferably identical combiner structure (2) are broadside coupled across a dielectric substrate (30) containing on one side the network of N radial outputs (31) and on its other side a set of N equispaced stubs (42) which are capacitively coupled through the dielectric substrate (30) to the N radial outputs (31). The divider structure (1) and the combiner structure (2) each comprise a dielectric disk (12, 22, respectively) on which is mounted a set of N radial impedance transformers (14, 24, respectively). Gross axial coupling is determined by the thickness of the dielectric layer (30). Rotating the disks (12, 22) with respect to each other effectuates fine adjustment in the degree of axial coupling.

Vaddiparty, Yerriah P. (Inventor)

1987-01-01

319

Radial power flattening in sodium fast reactors  

E-print Network

In order to improve a new design for a uranium startup sodium cooled fast reactor which was proposed at MIT, this thesis evaluated radial power flattening by varying the fuel volume fraction at a fixed U-235 enrichment of ...

Krentz-Wee, Rebecca (Rebecca Elizabeth)

2012-01-01

320

14 CFR 71.7 - Bearings, radials, and mileages.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 false Bearings, radials, and mileages...D, AND E AIRSPACE AREAS; AIR TRAFFIC SERVICE ROUTES; AND REPORTING POINTS § 71.7 Bearings, radials, and mileages. All bearings and radials in this part...

2010-01-01

321

Gas Chromatography Application Notes  

NSDL National Science Digital Library

This site includes application notes on gas chromatography from 2000-2005 which have been presented at conferences. The applications could serve as a source of experiments for advanced teaching labs and may also assist those interested in solving analytical problems that involve separations.

2011-05-20

322

Investigating Chromatography: selecting variables  

NSDL National Science Digital Library

This activity is a classroom investigation where students separate pigment in dyes in order to learn about mixtures and solutions. They use chromatography to design and experiment with a single variable to answer a question about which ink will separate the most - has the greatest variety of pigment.

Gerber, Nancy

323

Gas Chromatography Video  

NSDL National Science Digital Library

This is a high quality video module demonstrating the basics of gas chromatography. Highlights include different GC instruments and detectors as well as unique topics such as trouble shooting and interfacing the column that are not addressed in standard texts. This resource can be run (Shockwave Flash) from the home server or downloaded to your computer.

2011-05-26

324

Paper Chromatography of Thioureas  

Microsoft Academic Search

IN the course of a current investigation, it became necessary to separate and identify minute amounts of N-substituted thioureas. Paper chromatography suggested itself as the method of choice for this purpose, and a technique has now been worked out which gives satisfactory and reproducible results on some thirty thioureas investigated, separately or in complex mixtures.

Anders Kjær; Kurt Rubinstein

1953-01-01

325

Extending Paper Chromatography Inquiry  

ERIC Educational Resources Information Center

One of the "good old" standard activities middle school students seem to enjoy is paper chromatography. The procedures and materials needed are relatively simple and the results can be colorful. All too often, the activity ends just after these colorful results are obtained, cutting short the potential it holds for some further inquiry. With some…

Finson, Kevin

2004-01-01

326

Split Injection Gas Chromatography  

NSDL National Science Digital Library

This animation site deals specifically with split injection in gas chromatography. The animations are short (one to two minutes each) and can easily be shown in class as part of a lecture. They are extremely helpful in illustrating key components and concepts of chromatographic systems. Users are encouraged to explore the site and the other brief animations as well.

2011-05-11

327

Paper Chromatography with Leaves  

NSDL National Science Digital Library

In this activity on page 5 of the PDF, learners use chromatography to separate and identify pigments within various leaves. Learners soak leaf pieces in warmed rubbing alcohol and then dip coffee filter paper in the alcohol, lifting and separating the leaf pigments according to size.

Society, American C.

2010-01-01

328

Analyze Candy Using Chromatography  

NSDL National Science Digital Library

Learners analyze candy-coated sweets using chromatography. Learners use this method to separate the various dyes used to make colored candy. Learners can try this activity with different types of candy or with candy of different colors and compare the results.

Museum Of Science And Industry, Chicago

2012-01-01

329

Radial averages of astigmatic TEM images.  

PubMed

The Contrast Transfer Function (CTF) of an image, which modulates images taken from a Transmission Electron Microscope (TEM), is usually determined from the radial average of the power spectrum of the image (Frank, J., Three-dimensional Electron Microscopy of Macromolecular Assemblies, Oxford University Press, Oxford, 2006). The CTF is primarily defined by the defocus. If the defocus estimate is accurate enough then it is possible to demodulate the image, which is popularly known as the CTF correction. However, it is known that the radial average is somewhat attenuated if the image is astigmatic (see Fernando, K.V., Fuller, S.D., 2007. Determination of astigmatism in TEM images. Journal of Structural Biology 157, 189-200) but this distortion due to astigmatism has not been fully studied or understood up to now. We have discovered the exact mathematical relationship between the radial averages of TEM images with and without astigmatism. This relationship is determined by a zeroth order Bessel function of the first kind and hence we can exactly quantify this distortion in the radial averages of signal and power spectra of astigmatic images. The argument to this Bessel function is similar to an aberration function (without the spherical aberration term) except that the defocus parameter is replaced by the differences of the defoci in the major and minor axes of astigmatism. The ill effects due this Bessel function are twofold. Since the zeroth order Bessel function is a decaying oscillatory function, it introduces additional zeros to the radial average and it also attenuates the CTF signal in the radial averages. Using our analysis, it is possible to simulate the effects of astigmatism in radial averages by imposing Bessel functions on idealized radial averages of images which are not astigmatic. We validate our theory using astigmatic TEM images. PMID:18662790

Fernando, K Vince

2008-10-01

330

Cone thin-layer chromatography  

NASA Astrophysics Data System (ADS)

A new variant of chromatography, cone chromatography, is suggested. In this variant, a thin-layer chromatography (TLC) plate on a flexible support (for example, foil) is cone-shaped. This variant is compared with the classic linear and circular variants using chromatographic characteristics (retardation factor R f and efficiency H, ?m) and the time of chromatographing with ethanol as a mobile phase. Cone chromatography is intermediate in the series linear-cone-circular TLC variants.

Berezkin, V. G.; Kormishkina, E. V.

2008-08-01

331

Impact of radial migration on stellar and gas radial metallicity distribution  

E-print Network

Radial migration is defined as the change in guiding centre radius of stars and gas caused by gains or losses of angular momentum that result from gravitational interaction with non-axisymmetric structure. This has been shown to have significant impact on the metallicity distribution in galactic discs, and therefore affects the interpretation of Galactic archeology. We use a simulation of a Milky Way-sized galaxy to examine the effect of radial migration on the star and gas radial metallicity distribution. We find that both the star and gas component show significant radial migration. The stellar radial metallicity gradient remains almost unchanged but the radial metallicity distribution of the stars is broadened to produce a greater dispersion at all radii. However, the metallicity dispersion of the gas remains narrow. We find that the main drivers of the gas metallicity distribution evolution are metal enrichment and mixing: more efficient metal enrichment in the inner region maintains a negative slope in t...

Grand, Robert J J; Cropper, Mark

2014-01-01

332

Bioaffinity chromatography on monolithic supports  

Microsoft Academic Search

Affinity chromatography on monolithic supports is a powerful analytical chemical platform because it allows for fast analyses, small sample volumes, strong enrichment of trace biomarkers and applications in microchips. In this review, the recent research using monolithic materials in the field of bioaffinity chromatography (including immunochromatography) is summarized and discussed. After giving an introduction into affinity chromatography, information on different

Kishore K. R. Tetala; Beek van T. A

2010-01-01

333

High Performance Thin Layer Chromatography.  

ERIC Educational Resources Information Center

Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

Costanzo, Samuel J.

1984-01-01

334

Chromatography: Who Wrote the Note?  

NSDL National Science Digital Library

This lesson has students solving the mystery of a note by conducting chromatography. They will test different washable markers and see that different marker colors are made up of various pigments. They will compare and contrast the note chromatography with other chromatography results from a variety of markers.

Hansing, Rebecca

335

Classification of volcanoes of the Kane Patera Quadrangle of Io: Proportions of lava flows and pyroclastic flows  

NASA Technical Reports Server (NTRS)

Voyager 1 images show 14 volcanic centers wholly or partly within the Kane Patera quadrangle of Io, which are divided into four major classes: (1) shield with parallel flows; (2) shield with early radial fan shapd flows; (3) shield with radial fan shaped flows, surfaces of flows textured with longitudinal ridges; and (4) depression surrounded by plateau-forming scarp-bounded, untextured deposits. The interpretation attempted here hinges largely on the ability to distinguish lava flows from pyroclastic flows by remote sensing.

Elston, W. E.

1984-01-01

336

Numerical modeling of elution peak profiles in supercritical fluid chromatography. Part I-Elution of an unretained tracer  

SciTech Connect

When chromatography is carried out with high-density carbon dioxide as the main component of the mobile phase (a method generally known as 'supercritical fluid chromatography' or SFC), the required pressure gradient along the column is moderate. However, this mobile phase is highly compressible and, under certain experimental conditions, its density may decrease significantly along the column. Such an expansion absorbs heat, cooling the column, which absorbs heat from the outside. The resulting heat transfer causes the formation of axial and radial gradients of temperature that may become large under certain conditions. Due to these gradients, the mobile phase velocity and most physico-chemical parameters of the system (viscosity, diffusion coefficients, etc.) are no longer constant throughout the column, resulting in a loss of column efficiency, even at low flow rates. At high flow rates and in serious cases, systematic variations of the retention factors and the separation factors with increasing flow rates and important deformations of the elution profiles of all sample components may occur. The model previously used to account satisfactorily for the effects of the viscous friction heating of the mobile phase in HPLC is adapted here to account for the expansion cooling of the mobile phase in SFC and is applied to the modeling of the elution peak profiles of an unretained compound in SFC. The numerical solution of the combined heat and mass balance equations provides temperature and pressure profiles inside the column, and values of the retention time and efficiency for elution of this unretained compound that are in excellent agreement with independent experimental data.

Kaczmarski, Krzysztof [University of Tennessee and Rzeszow University of Technology, Poland; Guiochon, Georges A [ORNL

2010-01-01

337

Simulating retention in gas-liquid chromatography  

SciTech Connect

Accurate predictions of retention times, retention indices, and partition constants are a long sought-after goal for theoretical studies in chromatography. Configurational-bias Monte Carlo (CBMC) simulations in the Gibbs ensemble using the transferable potentials for phase equilibria-united atom (TraPPE-UA) force field have been carried out to obtain a microscopic picture of the partitioning of 10 alkane isomers between a helium vapor phase and a squalane liquid phase, a protypical gas-liquid chromatography system. The alkane solutes include some topological isomers that differ only in the arrangement of their building blocks (e.g., 2,5-dimethylhexane and 3,4-dimethylhexane), for which the prediction of the retention order is particularly difficult. The Kovats retention indices, a measure of the relative retention times, are calculated directly from the partition constants and are in good agreement with experimental values. The calculated Gibbs free energies of transfer for the normal alkanes conform to Martin's equation which is the basis of linear free energy relationships used in many process modeling packages. Analysis of radial distribution functions and the corresponding energy integrals does not yield evidence for specific retention structures and shows that the internal energy of solvation is not the main driving force for the separation of topological isomers in this system.

Martin, M.G.; Siepmann, J.I.; Schure, M.R.

1999-12-16

338

Waves in Radial Gravity Using Magnetic Fluid  

NASA Technical Reports Server (NTRS)

Terrestrial laboratory experiments studying various fluid dynamical processes are constrained, by being in an Earth laboratory, to have a gravitational body force which is uniform and unidirectional. Therefore fluid free-surfaces are horizontal and flat. Such free surfaces must have a vertical solid boundary to keep the fluid from spreading horizontally along a gravitational potential surface. In atmospheric, oceanic, or stellar fluid flows that have a horizontal scale of about one-tenth the body radius or larger, sphericity is important in the dynamics. Further, fluids in spherical geometry can cover an entire domain without any sidewall effects, i.e. have truly periodic boundary conditions. We describe spherical body-force laboratory experiments using ferrofluid. Ferrofluids are dilute suspensions of magnetic dipoles, for example magnetite particles of order 10 nm diameter, suspended in a carrier fluid. Ferrofluids are subject to an additional body force in the presence of an applied magnetic field gradient. We use this body force to conduct laboratory experiments in spherical geometry. The present study is a laboratory technique improvement. The apparatus is cylindrically axisymmetric. A cylindrical ceramic magnet is embedded in a smooth, solid, spherical PVC ball. The geopotential field and its gradient, the body force, were made nearly spherical by careful choice of magnet height-to-diameter ratio and magnet size relative to the PVC ball size. Terrestrial gravity is eliminated from the dynamics by immersing the "planet" and its ferrofluid "ocean" in an immiscible silicone oil/freon mixture of the same density. Thus the earth gravity is removed from the dynamics of the ferrofluid/oil interface and the only dynamically active force there is the radial magnetic gravity. The entire apparatus can rotate, and waves are forced on the ferrofluid surface by exterior magnets. The biggest improvement in technique is in the wave visualization. Fluorescing dye is added to the oil/freon mixture and an argon ion laser generates a horizontal light that can be scanned vertically. Viewed from above, the experiment is a black circle with wave deformations surrounded by a light background. A contour of the image intensity at any light sheet position gives the surface of the ferrofluid "ocean" at that "latitude". Radial displacements of the waves as a function of longitude are obtained by subtracting the contour line positions from a no-motion contour at that laser sheet latitude. The experiments are run by traversing the forcing magnet with the laser sheet height fixed and images are frame grabbed to obtain a time-series at one latitude. The experiment is then re-run with another laser-sheet height to generate a full picture of the three-dimensional wave structure in the upper hemisphere of the ball as a function of time. We concentrate here on results of laboratory studies of waves that are important in Earth's atmosphere and especially the ocean. To get oceanic scaling in the laboratory, the experiment must rotate rapidly (4-second rotation period) so that the wave speed is slow compared to the planetary rotation speed as in the ocean. In the Pacific Ocean, eastward propagating Kelvin waves eventually run into the South American coast. Theory predicts that some of the wave energy should scatter into coastal-trapped Kelvin waves that propagate north and south along the coast. Some of this coastal wave energy might then scatter into mid-latitude Rossby waves that propagate back westward. Satellite observations of the Pacific Ocean sea-surface temperature and height seem to show signatures of westward propagating mid-latitude Rossby waves, 5 to 10 years after the 1982-83 El Nino. The observational data is difficult to interpret unambiguously owing to the large range of motions that fill the ocean at shorter timescales. This series of reflections giving eastward, north- ward, and then westward traveling waves is observed cleanly in the laboratory experiments, confirming the theoretical expectations

Ohlsen, D. R.; Hart, J. E.; Weidman, P. D.

1999-01-01

339

Variable area radial turbine fabrication and test program  

NASA Technical Reports Server (NTRS)

A variable area radial turbine with a moveable nozzle sidewall was experimentally evaluated. The turbine was designed for an advanced variable capacity gas turbine rotorcraft engine. The turbine has a mass flow rate of 2.27 kg/sec (5.0 lbs/sec), and a rotor inlet temperature of 1477K (2200 F). Testing was conducted at a reduced inlet temperature, but the aerodynamic parameters and Reynolds numbers were duplicated. Overall performance was obtained for a range of nozzle areas from 50% to 100% of the maximum area. The test program determined the effect on performance of: (1) Moving the hub or shroud sidewall; (2) Sidewall-vane clearance leakage; (3) Vaneless space geometry change; and (4) Nozzle cooling flows. Data were obtained for a range of pressure ratios and speeds and are presented in a number of performance maps.

Rogo, C.

1986-01-01

340

Experimental evaluation of a translating nozzle sidewall radial turbine  

NASA Technical Reports Server (NTRS)

Studies have shown that reduced specific fuel consumption of rotorcraft engines can be achieved with a variable capacity engine. A key component in such an engine in a high-work, high-temperature variable geometry gas generator turbine. An optimization study indicated that a radial turbine with a translating nozzle sidewall could produce high efficiency over a wide range of engine flows but substantiating data were not available. An experimental program with Teledyne CAE, Toledo, Ohio was undertaken to evaluate the moving sidewall concept. A variety of translating nozzle sidewall turbine configurations were evaluated. The effects of nozzle leakage and coolant flows were also investigated. Testing was done in warm air (121 C). The results of the contractual program were summarized.

Roelke, Richard J.; Rogo, Casimir

1987-01-01

341

Cooled High-temperature Radial Turbine Program 2  

NASA Technical Reports Server (NTRS)

The objective of this program was the design and fabrication of a air-cooled high-temperature radial turbine (HTRT) intended for experimental evaluation in a warm turbine test facility at the LeRC. The rotor and vane were designed to be tested as a scaled version (rotor diameter of 14.4 inches diameter) of a 8.021 inch diameter rotor designed to be capable of operating with a rotor inlet temperature (RIT) of 2300 F, a nominal mass flow of 4.56 lbm/sec, a work level of equal or greater than 187 Btu/lbm, and efficiency of 86 percent or greater. The rotor was also evaluated to determine it's feasibility to operate at 2500 F RIT. The rotor design conformed to the rotor blade flow path specified by NASA for compatibility with their test equipment. Fabrication was accomplished on three rotors, a bladeless rotor, a solid rotor, and an air-cooled rotor.

Snyder, Philip H.

1991-01-01

342

A Mini Axial and a Permanent Maglev Radial Heart Pump§  

PubMed Central

The implantability and durability have been for decades the focus of artificial heart R&D. A mini axial and a maglev radial pump have been developed to meet with such requirements. The mini axial pump weighing 27g (incl.5g rotor) has an outer diameter of 21mm and a length of 10mm in its largest point, but can produce a maximal blood flow of 6l/min with 50mmHg pressure increase. Therefore, it is suitable for the patients of 40-60kg body weight. For other patients of 60-80kg or 80-100kg body weight, the mini axial pumps of 23mm and 25mm outer diameter had been developed before, these devices were acknowledged to be the world smallest LVADs by Guinness World Record Center in 2004. The permanent maglev radial pump weighing 150g is a shaft-less centrifugal pump with permanent magnetic bearings developed by the author. It needs no second coil for suspension of the rotor except the motor coil, different from all other maglev pumps developed in USA, Japan, European, etc. Thus no detecting and controlling systems as well as no additional power supply for maglev are necessary. The pump can produce a blood flow up to as large as 10l/min against 100mmHg pressure. An implantable and durable blood pump will be a viable alternative to natural donor heart for transplantation. PMID:19662120

Qian, Kun-Xi; Ru, Wei-Min; Wang, Hao; Jing, Teng

2007-01-01

343

A mini axial and a permanent maglev radial heart pump.  

PubMed

The implantability and durability have been for decades the focus of artificial heart R&D. A mini axial and a maglev radial pump have been developed to meet with such requirements.The mini axial pump weighing 27g (incl.5g rotor) has an outer diameter of 21mm and a length of 10mm in its largest point, but can produce a maximal blood flow of 6l/min with 50mmHg pressure increase. Therefore, it is suitable for the patients of 40-60kg body weight. For other patients of 60-80kg or 80-100kg body weight, the mini axial pumps of 23mm and 25mm outer diameter had been developed before, these devices were acknowledged to be the world smallest LVADs by Guinness World Record Center in 2004.The permanent maglev radial pump weighing 150g is a shaft-less centrifugal pump with permanent magnetic bearings developed by the author. It needs no second coil for suspension of the rotor except the motor coil, different from all other maglev pumps developed in USA, Japan, European, etc. Thus no detecting and controlling systems as well as no additional power supply for maglev are necessary. The pump can produce a blood flow up to as large as 10l/min against 100mmHg pressure.An implantable and durable blood pump will be a viable alternative to natural donor heart for transplantation. PMID:19662120

Qian, Kun-Xi; Ru, Wei-Min; Wang, Hao; Jing, Teng

2007-01-01

344

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

Microsoft Academic Search

A high-speed counter-current chromatography (HSCCC) method was developed for the preparative separation and purification of bergapten and imperatorin from the Chinese medicinal plant Cnidium monnieri (L.) Cusson. The crude extract was obtained by extraction with ethanol from the dried fruits of Cnidium monnieri (L.) Cusson under sonication. Preparative HSCCC with a two-phase solvent system composed of n-hexane–ethyl acetate–ethanol–water (5:5:5:5, v\\/v\\/v\\/v)

Hua-Bin Li; Feng Chen

2004-01-01

345

Preparative Separation and Isolation of Three Flavonoids and Three Phloroglucinol Derivatives from Hypericum japonicum Thumb. using High?Speed Countercurrent Chromatography by Stepwise Increasing the Flow Rate of the Mobile Phase  

Microsoft Academic Search

A preparative high?speed counter?current chromatography (HSCCC) was used to isolate and separate chemical compounds from the medicinal plant H. japonicum. First, the ethanol extract of H. japonicum was directly isolated by HSCCC without any preparation and three flavonoid glycosides including isoquercitrin, quercitrin, and quercetin?7?O?rhamnoside were successfully purified using a two?phase solvent system composed of ethyl acetate–ethanol–water at the volume ratio

Jinyong Peng; Guorong Fan; Yutian Wu

2006-01-01

346

Supercritical fluid chromatography  

SciTech Connect

Chromatographic separations with a supercritical fluid as the mobile phase were suggested more than 20 years ago. Availability of commercial hardware makes this technique more widely usable today. Many separations by this method are now carried out with supercritical carbon dioxide as the mobile phase and packed liquid-chromatography columns as the stationary phase. Although carbon dioxide has many practical advantages, including its near-ambient critical temperature and minimal interference with spectrometric detection, the use of other supercritical fluids or addition of modifiers to carbon dioxide may extend the applications of this technique. Some mixtures that are difficult to analyze by other chromatographic methods may be susceptible to separation by supercritical fluid chromatography. Mixtures that have been separated with supercritical carbon dioxide include resin acids with the empirical formula C/sub 20/H/sub 30/O/sub 2/ and ubiquinones from bacterial cell wall extracts of Legionella pneumophila. 60 refs., 8 figs.

Gere, D.R.

1983-10-21

347

Chromatography Can Separate!  

NSDL National Science Digital Library

In this chemistry activity, learners use thin layer chromatography to determine the molecular composition of different markers. First, they use pure rubbing alcohol as the liquid phase, then experiment with mixtures of alcohol and water to see which works best. Different black markers can be tried to see how their components compare. A quantitative measure of the "retention factor" is calculated to relate the distance traveled by the spot to the distance traveled by the mobile phase. A later experiment has learners try to identify an unknown ink sample by comparing it to known samples, and then opens it up to artistic pattern-making using chromatography and markers. The activity is written to be part of a kit, but the kit is not required.

Shaw, Maisie; Gomez, Maria

2010-01-01

348

Chromatography in Industry  

NASA Astrophysics Data System (ADS)

This review focuses on the chromatography research that has been carried out within industry or in close cooperation with industry and that has been reported in the scientific literature between 2006 and mid-2008. Companies in the health care sector, such as pharmaceutical and biotechnology companies, are the largest contributors. Industrial research seems to take place in an open environment in cooperation with academia, peer companies, and institutions. Industry appears ready to embrace new technologies as they emerge, but they focus strongly on making chromatography work robustly, reliably, rapidly, and automatically. “Hyphenated” systems that incorporate on-line sample-preparation techniques and mass-spectrometric detection are the rule rather than the exception. Various multidimensional separation methods are finding numerous applications. Strategies aimed at speeding up the development of new chromatographic methods remain the focus of attention. Also, there is a clear trend toward exploring chromatographic methods for parallel processing along with other strategies for high-throughput analysis.

Schoenmakers, Peter

2009-07-01

349

Chromatography with Spectrophotometric Detection  

Microsoft Academic Search

We describe a method for determining uric acid in serum by reversed-phase liquid chromatography with spectro- photometric detection at 280 nm. Serum, 100 ulis mixed with 100 u1of a solution containing, per liter, 70 ml of acetonitrile in sodium acetate (20 mmol\\/Iiter, pH 4.0) and 500 mg of the internal standard, adenine. The mixture is allowed to stand in an

Ernest J. Kiser; George F. Johnson; David L. Witte

350

Paper chromatography of lipides  

Microsoft Academic Search

Summary  Procedures for qualitative and quantitative paper chromatography of lipides have been described in detail, together with some\\u000a practical applications.\\u000a \\u000a With the monochain lipides it was found that one developing system serves universally. The long aliphatic chains essentially\\u000a determine the chromatographic properties so that suitable conditions for chromatographing any lipide or lipide-like entity\\u000a are predictable. For the same reason total analysis

H. Schlenk; Joanne L. Gellerman; Jerry A. Tillotson; H. K. Mangold

1957-01-01

351

Group invariant solutions for radial jet having finite fluid velocity at orifice  

Microsoft Academic Search

The group invariant solution for Prandtl's boundary layer equations for an incompressible fluid governing the flow in radial free, wall and liquid jets having finite fluid velocity at the orifice are investigated. For each jet a symmetry is associated with the conserved vector that was used to derive the conserved quantity for the jet elsewhere. This symmetry is then used

I. Naeem; R. Naz

2008-01-01

352

Radial interchange motions of plasma filaments  

SciTech Connect

Radial convection of isolated filamentary structures due to interchange motions in magnetized plasmas is investigated. Following a basic discussion of vorticity generation, ballooning, and the role of sheaths, a two-field interchange model is studied by means of numerical simulations on a biperiodic domain perpendicular to the magnetic field. It is demonstrated that a blob-like plasma structure develops dipolar vorticity and electrostatic potential fields, resulting in rapid radial acceleration and formation of a steep front and a trailing wake. While the dynamical evolution strongly depends on the amount of collisional diffusion and viscosity, the structure travels a radial distance many times its initial size in all parameter regimes in the absence of sheath dissipation. In the ideal limit, there is an inertial scaling for the maximum radial velocity of isolated filaments. This velocity scales as the acoustic speed times the square root of the structure size relative to the length scale of the magnetic field. The plasma filament eventually decelerates due to mixing and collisional dissipation. Finally, the role of sheath dissipation is investigated. When included in the simulations, it significantly reduces the radial velocity of isolated filaments. The results are discussed in the context of convective transport in scrape-off layer plasmas, comprising both blob-like structures in low confinement modes and edge localized mode filaments in unstable high confinement regimes.

Garcia, O. E.; Bian, N. H.; Fundamenski, W. [Association EURATOM-Risoe National Laboratory, P.O. Box 49, OPL-128 Risoe, DK-4000 Roskilde (Denmark); School of Physics and Astronomy, University of Manchester, Manchester M60 1QD (United Kingdom); EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

2006-08-15

353

Radial velocity studies of cool stars.  

PubMed

Our current view of exoplanets is one derived primarily from solar-like stars with a strong focus on understanding our Solar System. Our knowledge about the properties of exoplanets around the dominant stellar population by number, the so-called low-mass stars or M dwarfs, is much more cursory. Based on radial velocity discoveries, we find that the semi-major axis distribution of M dwarf planets appears to be broadly similar to those around more massive stars and thus formation and migration processes might be similar to heavier stars. However, we find that the mass of M dwarf planets is relatively much lower than the expected mass dependency based on stellar mass and thus infer that planet formation efficiency around low-mass stars is relatively impaired. We consider techniques to overcome the practical issue of obtaining good quality radial velocity data for M dwarfs despite their faintness and sustained activity and emphasize (i) the wavelength sensitivity of radial velocity signals, (ii) the combination of radial velocity data from different experiments for robust detection of small amplitude signals, and (iii) the selection of targets and radial velocity interpretation of late-type M dwarfs should consider H? behaviour. PMID:24664922

Jones, Hugh R A; Barnes, John; Tuomi, Mikko; Jenkins, James S; Anglada-Escude, Guillem

2014-04-28

354

Periodic radial velocity variations in RU Lupi  

NASA Astrophysics Data System (ADS)

Context: RU Lup is a Classical T Tauri star with unusually strong emission lines, which has been interpreted as manifestations of accretion. Recently, evidence has accumulated that this star might have a variable radial velocity. Aims: We intended to investigate in more detail the possible variability in radial velocity using a set of 68 high-resolution spectra taken at the VLT (UVES), the AAT (UCLES) and the CTIO (echelle). Methods: Using standard cross-correlation techniques, we determined the radial velocity of RU Lup. We analysed these results with Phase-dispersion minimization and the Lomb-Scargle periodogram and searched for possible periodicities in the obtained radial velocities. We also analysed changes in the absorption line shapes and the photometric variability of RU Lup. Results: Our analysis indicated that RU Lup exhibits variations in radial velocity with a periodicity of 3.71 days and an amplitude of 2.17 km s-1. These variations can be explained by the presence of large spots, or groups of spots, on the surface of RU Lup. We also considered a low-mass companion and stellar pulsations as alternative sources for these variations but found these to be unlikely.

Stempels, H. C.; Gahm, G. F.; Petrov, P. P.

2007-01-01

355

Characteristics of adrenoceptors in the human radial artery: Clinical implications  

Microsoft Academic Search

Objectives: The radial artery has been suggested to be spastic. Endogenous and exogenous catecholamines and the use of ?-blockers may be related to radial artery spasm, but the characteristics of adrenoceptors in this artery are unknown. This study was designed to characterize the ?- and ?-adrenoceptor in the human radial artery. Methods: Ring segments of the radial artery (n = 59)

Guo-Wei He; Cheng-Qin Yang

1998-01-01

356

Manufacturing of Precision Forgings by Radial Forging  

SciTech Connect

Radial forging is a multi purpose incremental forging process using four tools on the same plane. It is widely used for the forming of tool steels, super alloys as well as titanium- and refractory metals. The range of application goes from reducing the diameters of shafts, tubes, stepped shafts and axels, as well as for creating internal profiles for tubes in Near-Net-Shape and Net-Shape quality. Based on actual development of a weight optimized transmission input shaft, the specific features of radial forging technology is demonstrated. Also a Finite Element Model for the simulation of the process is shown which leads to reduced pre-processing effort and reduced computing time compared to other published simulation methods for radial forging. The finite element model can be applied to quantify the effects of different forging strategies.

Wallner, S.; Harrer, O.; Buchmayr, B. [Chair of Metal Forming, Department Product Engineering, University of Leoben, Franz Josef Strasse 18, 8700 Leoben (Austria); Hofer, F. [GFM GmbH, Ennser Strasse 14, 4403 Steyr (Austria)

2011-01-17

357

Dispersion-free radial transmission lines  

DOEpatents

A dispersion-free radial transmission line ("DFRTL") preferably for linear accelerators, having two plane conductors each with a central hole, and an electromagnetically permeable material ("EPM") between the two conductors and surrounding a channel connecting the two holes. At least one of the material parameters of relative magnetic permeability, relative dielectric permittivity, and axial width of the EPM is varied as a function of radius, so that the characteristic impedance of the DFRTL is held substantially constant, and pulse transmission therethrough is substantially dispersion-free. Preferably, the EPM is divided into concentric radial sections, with the varied material parameters held constant in each respective section but stepwise varied between sections as a step function of the radius. The radial widths of the concentric sections are selected so that pulse traversal time across each section is the same, and the varied material parameters of the concentric sections are selected to minimize traversal error.

Caporaso, George J. (Livermore, CA); Nelson, Scott D. (Patterson, CA)

2011-04-12

358

Generalized Radially Self-Accelerating Helicon Beams  

NASA Astrophysics Data System (ADS)

We report, in theory and experiment, on a new class of optical beams that are radially self-accelerating and nondiffracting. These beams continuously evolve on spiraling trajectories while maintaining their amplitude and phase distribution in their rotating rest frame. We provide a detailed insight into the theoretical origin and characteristics of radial self-acceleration and prove our findings experimentally. As radially self-accelerating beams are nonparaxial and a solution to the full scalar Helmholtz equation, they can be implemented in many linear wave systems beyond optics, from acoustic and elastic waves to surface waves in fluids and soft matter. Our work generalized the study of classical helicon beams to a complete set of solutions for rotating complex fields.

Vetter, Christian; Eichelkraut, Toni; Ornigotti, Marco; Szameit, Alexander

2014-10-01

359

Note on radial correlation factors of atoms  

NASA Astrophysics Data System (ADS)

A peculiar property is reported for the pth order (2 ? p ? N) radial correlation factor of an N-electron atom (N ? 2). When the pth electron goes away from the nucleus, the correlation factor reduces, apart from the constant unity, to the ratio between the (p ? 1)th order reduced radial densities of the (N ? 1)- and N-electron atoms, where both atoms are considered to be in their non-degenerate ground states. The result implies that an ‘electron annihilation function’ for the reduced densities is defined by a particular case of the correlation factor. A numerical illustration is given for a simple system.

Koga, Toshikatsu

2014-11-01

360

Accordion Phenomenon in the Radial Artery  

PubMed Central

The accordion phenomenon is a well-known finding mechanism in the field of interventional cardiology. It is a benign condition and has mainly been described in tortuous coronary arteries during percutaneous coronary interventions. It is believed to be induced by a stiff guidewire. However, this phenomenon has not been observed previously in the radial artery. We present a case of accordion phenomenon in the radial artery, which was successfully resolved after the catheters and the wire were retrieved, with the pseudolesions found to have completely disappeared in subsequent image findings. PMID:24516747

Dahdouh, Ziad S.; Abdel-Massih, Tony; Sarkis, Antoine; Grollier, Gilles

2014-01-01

361

Aircraft radial-belted tire evaluation  

NASA Technical Reports Server (NTRS)

An overview is given of the ongoing joint NASA/FAA/Industry Surface Traction And Radial Tire (START) Program being conducted at NASA Langley's Aircraft Landing Dynamics Facility (ALDF). The START Program involves tests using three different tire sizes to evaluate tire rolling resistance, braking, and cornering performance throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Preliminary results from recent 40 x 14 size bias-ply, radial-belted, and H-type aircraft tire tests are discussed. The paper concludes with a summary of the current program status and planned ALDF test schedule.

Yager, Thomas J.; Stubbs, Sandy M.; Davis, Pamela A.

1990-01-01

362

Modeling of thermal processes in high pressure liquid chromatography II. Thermal heterogeneity at very high pressures  

SciTech Connect

Advanced instruments for liquid chromatography enables the operation of columns packed with sub-2 {micro}m particles at the very high inlet pressures, up to 1000 bar, that are necessary to achieve the high column efficiency and the short analysis times that can be provided by the use of these columns. However, operating rather short columns at high mobile phase velocities, under high pressure gradients causes the production of a large amount of heat due to the viscous friction of the eluent percolating through the column bed. The evacuation of this heat causes the formation of significant axial and radial temperature gradients. Due to these thermal gradients, the retention factors of analytes and the mobile phase velocity are no longer constant throughout the column. The consequence of this heat production is a loss of column efficiency. We previously developed a model combining the heat and mass balance of the column, the equations of flow through porous media, and a linear isotherm model of the analyte. This model was solved and validated for conventional columns operated under moderate pressures. We report here on the results obtained when this model is applied to columns packed with very fine particles, operated under very high pressures. These results prove that our model accounts well for all the experimental results. The same column that elutes symmetrical, nearly Gaussian peaks at low flow rates, under relatively low pressure drops, provides strongly deformed, unsymmetrical peaks when operated at high flow rates, under high pressures, and under different thermal environments. The loss in column efficiency is particularly important when the column wall is kept at constant temperature, by immersing the column in a water bath.

Kaczmarski, Krzysztof [University of Tennessee and Rzeszow University of Technology, Poland; Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Guiochon, Georges A [ORNL

2009-01-01

363

Efficiency in supercritical fluid chromatography with different superficially porous and fully porous particles ODS bonded phases.  

PubMed

The chromatographic efficiency, in terms of plate number per second, was dramatically improved by the introduction of sub-two microns particles with ultra-high pressure liquid chromatography (UHPLC). On the other hand, the recent development of superficially porous particles, called core-shell or fused-core particles, appears to allow the achievement of the same efficiency performances at higher speed without high pressure drops. CO?-based mobile phases exhibiting much lower viscosities than aqueous based mobile phases allow better theoretical efficiencies, even with 3-5 ?m particles, but with relative low pressure drops. They also allow much higher flow rates or much longer columns while using conventional instruments capable to operate below 400 bar. Moreover, the use of superficially porous particles in SFC could enhance the chromatographic performances even more. The kinetic behavior of ODS phases bonded on these particles was studied, with varied flow rates, outlet (and obviously inlet) pressures, temperatures, by using a homologous series (alkylbenzenes) with 10% modifier (methanol or acetonitrile) in the carbon dioxide mobile phase. Results were also compared with classical fully porous particles, having different sizes, from 2.5 to 5 ?m. Superior efficiency (N) and reduced h were obtained with these new ODS-bonded particles in regards to classical ones, showing their great interest for use in SFC. However, surprising behavior were noticed, i.e. the increase of the theoretical plate number vs. the increase of the chain length of the compounds. This behavior, opposite to the one classically reported vs. the retention factor, was not depending on the outlet pressure, but on the flow rate and the temperature changes. The lower radial trans-column diffusion on this particle types could explain these results. This diffusion reduction with these ODS-bonded superficially porous particles seems to decrease with the increase of the residence time of compounds. PMID:22192562

Lesellier, E

2012-03-01

364

GE Healthcare Data File 11-0026-34 AA Hydrophobic interaction chromatography  

E-print Network

to as hydrophobic interaction chromatography (HIC) media. GE Healthcare produces a wide range of HIC mediaGE Healthcare Data File 11-0026-34 AA Hydrophobic interaction chromatography Butyl-S Sepharose 6 solutes Media characteristics Butyl-S Sepharose 6 Fast Flow is based on rigid, highly cross

Lebendiker, Mario

365

Development of a 3D Model for Packed Bed Liquid Chromatography in Micro-columns  

Microsoft Academic Search

One-dimensional models of column liquid chromatography are today widely applied due to some obvious advantages. These models are easy to set up, they can be computed very fast, and they can often predict experimental results reasonably well. However, one-dimensional chromatography models also have some serious disadvantages, mainly because the applied homogeneity assumptions neglect important information on flow conditions and concentration

Sebastian Schnittert; Remo Winz; Eric Von Lieres

2009-01-01

366

Gas Chromatography Experiment  

NSDL National Science Digital Library

This Microsoft Word document describes a Gas Chromatography experiment involving the separation and quantitation of four butyl alcohol isomers. It has a complete background about the components of a GC instrument (with labeled pictures) and their functions. The exercise includes a section devoted to the measurement of response factors of the detector in use (here an FID). This would be a good experiment for a new faculty member to use as is, with slight modification to make it relevant to the particular GC system to be used.

2011-05-20

367

High Performance Liquid Chromatography  

NSDL National Science Digital Library

The North Carolina Community College System BioNetwork's interactive eLearning tools (IETs) are reusable chunks of training that can be deployed in a variety of courses or training programs. IETs are designed to enhance, not replace hands-on training. Learners are able to enter a hands-on lab experience better prepared and more confident. This particular IET delves into High Performance Liquid Chromatography (HPLC) and its application in discovering the amount of caffeine in two different drinks. Flash is required to participate in this learning module.

2013-08-06

368

COMPUTATION OF THE FREE SURFACE FLOW OF A THIN LIQUID FILM AT ZERO AND NORMAL GRAVITY  

Microsoft Academic Search

The results of numerical computations are presented for the free surface flow of a thin liquid film in the presence or absence of a gravitational body force. Three different flow systems were studied: a falling film down a vertical wall, plane and radial film flows under zero gravity, and plane and radial film flows along a horizontal plate in the

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

1990-01-01

369

Solar like stars radial velocities (Zechmeister+, 2013)  

NASA Astrophysics Data System (ADS)

The catalogue is composed of radial velocity timeseries for 31 stars obtained with three instruments (CES+LC,CES+VLC,HARPS). Additionally the HARPS timeseries include activity indicators (logR'HK and Bisector span, FWHM, and Contrast of the cross correlation function). (4 data files).

Zechmeister, M.; Kuerster, M.; Endl, M.; Lo Curto, G.; Hartman, H.; Nilsson, H.; Henning, T.; Hatzes, A. P.; Cochran, W. D.

2012-11-01

370

HPLC- High Performance Liquid Chromatography  

NSDL National Science Digital Library

This primer on High Performance Liquid Chromatography (HCLC) gives a brief history and definition of liquid chromatography (LC), LC techniques, and defines both HPLC and UltraPerformance Liquid Chromatography (UPLC Technology). The other chapters of the primer are available on the left side of the page: How Does High Performance Liquid Chromatography Work?, Identifying and Quantitating Compounds, HPLC Column Hardware, and HPLC Separation Modes. An appendix which defines HPLC nomenclature is also available. Each section is pepper with helpful and clear illustrations to help users visualize the processes and procedures presented.

2011-05-19

371

Experimental Characterization of Piezoelectric Radial Field Diaphragms for Fluidic Control  

NASA Technical Reports Server (NTRS)

NASA has recently developed a new piezoelectric actuator, the Radial Field Diaphragm or RFD. This actuator uses a radially-directed electric field to generate concentric out-of-plane (Z-axis) motion that allows this packaged device to be used as a pump or valve diaphragm. In order to efficiently use this new active device, experimental determination of pressure, flow rate, mechanical work, power consumption and overall efficiency needs to be determined by actually building a pump. However, without an optimized pump design, it is difficult to assess the quality of the data, as these results are inherent to the actual pump. Hence, separate experiments must be conducted in order to generate independent results to help guide the design criteria and pump quality. This paper focuses on the experiments used to generate the RFD's operational parameters and then compares these results to the experimentally determined results of several types of ball pumps. Also discussed are how errors are inherently introduced into the experiments, the pump design, experimental hardware and their effects on the overall system efficiency.

Bryant, R. G.; Kavli, S. E.; Thomas, R. A., Jr.; Darji, K. J.; Mossi, K. M.

2004-01-01

372

Diagnostics of a Subsurface Radial Outflow From a Sunspot  

E-print Network

We measure the mean frequencies of acoustic waves propagating toward and away from a sunspot employing a spot-centered Fourier-Hankel decomposition of p-mode amplitudes as measured from a set of observations made at the South Pole in 1991. We demonstrate that there is a significant frequency shift between the inward and outward traveling waves which is consistent with the Doppler effect of a radial outflow from the sunspot. For p-modes of temporal frequencies of 3 mHz it is observed that the frequency shift decreases slightly with spatial frequency, for modes with degree l between 160 to 600. From the l dependence of the frequency shift, we infer that the mean radial outflow within the observed annular region (which extends between 30 and 137 Mm from the spot) increases nearly linearly with depth, reaching a magnitude of about 200 m/s at a depth of 20 Mm. This outflow exhibits properties similar to flows recently reported by Lindsey, et al. (1996) using spatially sensitive local helioseismic techniques.

D. C. Braun; Y. Fan; C. Lindsey; S. M. Jefferies

1996-03-15

373

Development of a thermal and structural analysis procedure for cooled radial turbines  

NASA Technical Reports Server (NTRS)

A procedure for computing the rotor temperature and stress distributions in a cooled radial turbine are considered. Existing codes for modeling the external mainstream flow and the internal cooling flow are used to compute boundary conditions for the heat transfer and stress analysis. The inviscid, quasi three dimensional code computes the external free stream velocity. The external velocity is then used in a boundary layer analysis to compute the external heat transfer coefficients. Coolant temperatures are computed by a viscous three dimensional internal flow cade for the momentum and energy equation. These boundary conditions are input to a three dimensional heat conduction code for the calculation of rotor temperatures. The rotor stress distribution may be determined for the given thermal, pressure and centrifugal loading. The procedure is applied to a cooled radial turbine which will be tested at the NASA Lewis Research Center. Representative results are given.

Kumar, Ganesh N.; Deanna, Russell G.

1988-01-01

374

Temperature Gradient Method for Continuous Countercurrent Gas–Liquid Chromatography  

Microsoft Academic Search

Continuous countercurrent gas–liquid chromatography (CCGLC), where the gas and liquid phases move countercurrently and the sample can be introduced continuously, is a method suitable for separating binary sample systems. The flow ratio of the gas and liquid phases (G\\/L) in CCGLC should be between the partition coefficients of the two components to be separated. However, the larger the difference between

Katsuya Sato; Osamu Motokawa; Katsunori Watabe; Toshihide Ihara; Toshiyuki Hobo

1993-01-01

375

The Stationary Condensation and Radial Outflow of a Liquid Film on a Horizontal Disk  

NASA Technical Reports Server (NTRS)

The application of capillary screen liquid acquisition devices to space-based cryogenic propulsion systems is expected to necessitate thermodynamic conditioning in order to stabilize surface tension retention characteristics. The present results have been obtained in the framework of the research of low gravity condensation-flow processes for conditioning cryogenic liquid acquisition devices. The following system is studied: On the top of a subcooled horizontal disk, a liquid film condenses from the ambient saturated vapor. The liquid is forcedly removed at the disk edge, and there is an outward radial flow of the film. Stationary regimes of the flow are uncovered such that (i) the gravity is negligible, being eclipsed by the capillary forces; (ii) the film thickness is everywhere much smaller than the disk radius; and (iii) the slow-flow lubrication approximation is valid. A nonlinear differential equation for the film thickness as a function of the radial coordinate is obtained. The (two-dimensional) fields of velocities, temperature and pressure in the film are explicitly determined by the radial profile of its thickness. The equilibrium is controlled by two parameters: (i) the vapor-disk difference of temperatures and (ii) the liquid exhaust rate. For the flow regimes with a nearly uniform film thickness, the governing equation linearizes, and the film interface is analytically predicted to have a concave-up quartic parabola profile. Thus, perhaps counter-intuitively, the liquid film is thicker at the edge and thinner at the center of the disk.

Bolshinskiy, Leonid; Frenkel, Alexander

2008-01-01

376

Review of radial dose profiles for heavy ions  

SciTech Connect

Average energy deposited per unit mass in a cylindrical shell formed between radial distance r and r + dr from the trajectory of incident ions is defined as the radial dose D(r). Variation of D(r) as a function of radial distance is the radial dose profile. This radial dose profile information has been used by others to develop biophysical models of radiation effects. Radial dose profiles for heavy ions also provide data that can be checked against calculations made by different track structure codes based on continuous slowing down models or Monte Carlo methods. In addition radial dose profiles can also be determined from measured event size distributions. By comparing radial dose from two different experimental techniques, a direct evaluation of different experimental procedures and methods can be made. In this document we review the experimental measurement technique for determination of radial dose profiles, and the experimental data available for different heavy ions at different energies. 15 refs., 5 figs.

Varma, M.N.; Baum, J.W.

1987-01-01

377

A radial non-uniform helicon equilibrium discharge model  

NASA Astrophysics Data System (ADS)

Helicon discharges have attracted great attention in the electric propulsion community in recent years. To acquire the equilibrium properties, a self-consistent model is developed, which combines the helicon/Trivelpiece—Gould (TG) waves-plasma interaction mechanism and the plasma flow theory under the confinement of the magnetic field. The calculations reproduce the central peak density phenomenon observed in the experiments. The results show that when operating in the wave coupling mode, high magnetic field strength B0 results in the deviation of the central density versus B0 from the linear relationship, while the density rise becomes flatter as the radiofrequency (rf) input power Prf grows, and the electron temperature Te radial profile is mainly determined by the characteristic of the rf energy deposition. The model could provide suggestions in choosing the B0 and Prf for medium power helicon thrusters.

Cheng, Yu-Guo; Cheng, Mou-Sen; Wang, Mo-Ge; Li, Xiao-Kang

2014-10-01

378

Continuous Spore Disruption Using Radially Focused, High-Frequency Ultrasound  

SciTech Connect

ABSTRACT-We report on the development of a novel, continuous-flow, radially focused ultrasonic disruptor capable of lysing Bacillus spores in the absence of added chemical denaturants, enzymes, or microparticles. Greater than 99% disruption was achieved for Bacillus globigii spores and Escherichia coli and Bacillus subtilis vegetative cells with sample residence times of 62, 12, and 12 s, respectively. Microscopic and SEM images indicated that at equivalent power levels, the incidence of cell death or loss of viability typically exceeded the efficiency of (visible) cell lysis. However, semiquantitative PCR showed up to a 1000-fold increase in intracellular DNA availability from ultrasonically disrupted spores, and liberated DNA was intact and available for subsequent detection.

Chandler, Darrell P. (OFFICE OF FELLOWSHIP PROG); Brown, Jeremy D. (ASSOC WESTERN UNIVERSITY); Bruckner-Lea, Cynthia J. (BATTELLE (PACIFIC NW LAB)); Olson, Lydia (University of Utah); Posakony, Gerald J. (BATTELLE (PACIFIC NW LAB)); Stults, Jennie R. (LOS ALAMOS TECH ASSOC); Valentine, Nancy B. (BATTELLE (PACIFIC NW LAB)); Bond, Leonard J. (BATTELLE (PACIFIC NW LAB))

2000-12-01

379

Radial solidification of Al-Si alloys in the presence of a rotating magnetic field  

NASA Astrophysics Data System (ADS)

We study the flow field during the radial solidification of an Al-7wt pct Si melt inside a cylindrical cavity with cooled side walls which is placed in a rotating magnetic field (RMF). The solidification process is simulated by means of a continuum model which is implemented in a code which solves the axisymmetric Navier-Stokes equations. We first analyze the start-up of the buoyancy-driven convection driven by the radial heat flux in absence of the RMF. We show that the initial large vortex breaks up into three smaller one. The resulting radial temperature profiles are compared with experimental data. Second, we study how the vortex structure is modified by the application of small RMF's.

Travnikov, V.; Nikrityuk, P. A.; Eckert, K.; Räbiger, D.; Odenbach, S.; Eckert, S.

2012-07-01

380

Multiplex gas chromatography  

NASA Technical Reports Server (NTRS)

The principles of the multiplex gas chromatography (GC) technique, which is a possible candidate for chemical analysis of planetary atmospheres, are discussed. Particular attention is given to the chemical modulators developed by present investigators for multiplex GC, namely, the thermal-desorption, thermal-decomposition, and catalytic modulators, as well as to mechanical modulators. The basic technique of multiplex GC using chemical modulators and a mechanical modulator is demonstrated. It is shown that, with the chemical modulators, only one gas stream consisting of the carrier in combination with the components is being analyzed, resulting in a simplified instrument that requires relatively few consumables. The mechanical modulator demonstrated a direct application of multiplex GC for the analysis of gases in atmosphere of Titan at very low pressures.

Valentin, Jose R.

1990-01-01

381

P wave radial anisotropy tomography of the upper mantle beneath the North China Craton  

NASA Astrophysics Data System (ADS)

present the first P wave radial anisotropy tomography of the crust and upper mantle beneath the North China Craton (NCC), determined using a large number of high-quality arrival-time data of local earthquakes and teleseismic events. Our results show a prominent high-velocity (high-V) anomaly down to ˜250 km depth beneath the Ordos block, a high-V anomaly in the mantle transition zone beneath the eastern NCC, and a low-velocity (low-V) anomaly down to ˜300 km depth beneath the Trans-North China Orogen (TNCO). The Ordos block exhibits significant negative radial anisotropy (i.e., vertical Vp > horizontal Vp), suggesting that its cratonic lithosphere has kept the frozen-in anisotropy formed by vertical growth via high-degree melting mantle plume in the early Earth. Prominent low-V anomalies with positive radial anisotropy (i.e., horizontal Vp > vertical Vp) exist beneath the Qilian and Qaidam blocks down to ˜400 km depth, suggesting that the horizontal material flow resulting from the Tibetan Plateau is blocked by the Ordos thick lithosphere. Beneath the eastern NCC, high-V anomalies with negative radial anisotropy exist in the upper mantle, possibly reflecting sinking remains of the Archean cratonic lithosphere. A high-V anomaly with positive radial anisotropy is revealed in the mantle transition zone under the eastern NCC, which reflects the stagnant Pacific slab.

Wang, Jian; Wu, Huohua; Zhao, Dapeng

2014-06-01

382

Radial inlet guide vanes for a combustor  

DOEpatents

A combustor may include an interior flow path therethrough, a number of fuel nozzles in communication with the interior flow path, and an inlet guide vane system positioned about the interior flow path to create a swirled flow therein. The inlet guide vane system may include a number of windows positioned circumferentially around the fuel nozzles. The inlet guide vane system may also include a number of inlet guide vanes positioned circumferentially around the fuel nozzles and adjacent to the windows to create a swirled flow within the interior flow path.

Zuo, Baifang; Simons, Derrick; York, William; Ziminsky, Willy S

2013-02-12

383

TMT and Exoplanet Radial Velocity Surveys  

NASA Astrophysics Data System (ADS)

With echelle spectrometers on the verge of crossing over the 0.1 m/s radial velocity (RV) measurement precision threshold needed to detect habitable Earth mass planets around Sun-like stars, conducing such surveys on state-of-the-art telescopes is an imperative. RV exoplanets surveys conducted with the optical and infrared echelle spectrometers being built for the TMT have the potential to complete a census of the population of Earth-mass planets in our local stellar neighborhood. The detection of such systems will provide a valuable stellar sample for follow-up exoplanet studies which would characterize the atmospheres of these or additional planets found in these nearby solar systems. Here, we will further discuss the impact of the TMT on radial velocity exoplanet surveys.

Tanner, Angelle; Crossfield, Ian

2014-07-01

384

A radially expanding sheath for urethral dilation.  

PubMed

Urethral trauma caused by urethral dilation often leads to complications including gross hemorrhage and inflammation. The injury of the urethral mucosa is, in a large part, due to the shearing forces imposed on it during the introduction of dilation devices. In this article, a radially expanding sheath for urethral dilation is hypothesized by the authors. This device aims to reduce the axial forces during the insertion of dilators, thereby protecting the urethral mucosa from friction. When performing the endoscopy, the device could act as a barrier between urethral mucosa and the endoscope. Moreover, in the situation of encountering difficulties in catheterization, the sheath could also be used as a guide-wire to lead the catheter through its lumen course. Thus, it is proposed that this radially expanding sheath could be a potential powerful approach for reducing the risks and complications of urethral dilation. PMID:19589646

Hu, Zheng; Ma, Xin; Li, Hong-zhao; Wang, Chao; Ye, Da-wei; Gong, Dao-jing; Zhang, Xu

2009-10-01

385

Radial spline assembly for antifriction bearings  

NASA Technical Reports Server (NTRS)

An outer race carrier is constructed for receiving an outer race of an antifriction bearing assembly. The carrier in turn is slidably fitted in an opening of a support wall to accommodate slight axial movements of a shaft. A plurality of longitudinal splines on the carrier are disposed to be fitted into matching slots in the opening. A deadband gap is provided between sides of the splines and slots, with a radial gap at ends of the splines and slots and a gap between the splines and slots sized larger than the deadband gap. With this construction, operational distortions (slope) of the support wall are accommodated by the larger radial gaps while the deadband gaps maintain a relatively high springrate of the housing. Additionally, side loads applied to the shaft are distributed between sides of the splines and slots, distributing such loads over a larger surface area than a race carrier of the prior art.

Moore, Jerry H. (inventor)

1993-01-01

386

On Radially Symmetric Solutions to Conservation Laws  

Microsoft Academic Search

\\u000a Radially symmetric solutions to multi-dimensional systems of conservations laws are important in applications and computations,\\u000a as well as in the general theory of conservative systems. Notwithstanding their one-dimensional nature they are poorly understood.\\u000a In particular this is true for the Euler equations in gas-dynamics. After a short review of symmetric solutions to the Euler\\u000a system, we introduce a scalar model

Helge Kristian Jenssen

387

Variational method for integrating radial gradient field  

NASA Astrophysics Data System (ADS)

We propose a variational method for integrating information obtained from circular fringe pattern. The proposed method is a suitable choice for objects with radial symmetry. First, we analyze the information contained in the fringe pattern captured by the experimental setup and then move to formulate the problem of recovering the wavefront using techniques from calculus of variations. The performance of the method is demonstrated by numerical experiments with both synthetic and real data.

Legarda-Saenz, Ricardo; Brito-Loeza, Carlos; Rivera, Mariano; Espinosa-Romero, Arturo

2014-12-01

388

Radial SI latches vibration test data review  

NASA Technical Reports Server (NTRS)

Dynamic testing of the Space Telescope Scientific Instrument Radial Latches was performed as specified by the designated test criteria. No structural failures were observed during the test. The alignment stability of the instrument simulator was within required tolerances after testing. Particulates were discovered around the latch bases, after testing, due to wearing at the B and C latch interface surfaces. This report covers criteria derivation, testing, and test results.

Harrison, P. M.; Smith, J. L.

1984-01-01

389

Radial transport of dust in spiral galaxies  

E-print Network

Motivated by recent observations which detect dust at large galactocentric distances in the disks of spiral galaxies, we propose a mechanism of outward radial transport of dust by spiral stellar density waves. We consider spiral galaxies in which most of dust formation is localized inside the corotation radius. We show that in the disks of such spiral galaxies, the dust grains can travel over radial distances that exceed the corotation radius by roughly 25%. A fraction of the dust grains can be trapped on kidney-shaped stable orbits between the stellar spiral arms and thus can escape the destructive effect of supernova explosions. These grains form diffuse dusty spiral arms, which stretch 4-5 kpc from the sites of active star formation. About 10% of dust by mass injected inside corotation, can be transported over radial distances 3-4 kpc during approximately 1.0 Gyr. This is roughly an order of magnitude more efficient than can be provided by the turbulent motions.

E. I. Vorobyov; Yu. A. Shchekinov

2005-08-13

390

Radial transport of dust in spiral galaxies  

E-print Network

Motivated by recent observations which detect dust at large galactocentric distances in the disks of spiral galaxies, we propose a mechanism of outward radial transport of dust by spiral stellar density waves. We consider spiral galaxies in which most of dust formation is localized inside the corotation radius. We show that in the disks of such spiral galaxies, the dust grains can travel over radial distances that exceed the corotation radius by roughly 25%. A fraction of the dust grains can be trapped on kidney-shaped stable orbits between the stellar spiral arms and thus can escape the destructive effect of supernova explosions. These grains form diffuse dusty spiral arms, which stretch 4-5 kpc from the sites of active star formation. About 10% of dust by mass injected inside corotation, can be transported over radial distances 3-4 kpc during approximately 1.0 Gyr. This is roughly an order of magnitude more efficient than can be provided by the turbulent motions.

Vorobyov, E I; Shchekinov, Yu. A.

2006-01-01

391

A self-organizing radial basis network for estimating riverine fish diversity  

NASA Astrophysics Data System (ADS)

SummaryIn aquatic ecosystems, particularly rivers, hydrology plays a key role in structuring and maintaining habitats and flow regimes that influence ecological sustainability. Flow regime assessment in Taiwan has been facilitated recently by the Taiwan Eco-hydrologic Indicator System (TEIS). In this study, the self-organizing feature map (SOM) and radial basis function (RBF) neural network are combined to produce a self-organizing radial basis network (SORBN) that takes the advantages of both methods for strengthening the power of presentation and reliability of estimation. The SORBN is proposed to estimate the diversity of fish communities based on the TEIS and historic fish community composition at 36 locations in Taiwan. The discharge data are available for a minimum of 20 years. Data analysis applying a moving average method to the TEIS statistics is used to reflect the effects of antecedent flow conditions on fish diversity. Results indicate the hybrid SORBN not only effectively categorizes stream flow data but also reasonably identifies relationships between flow regime and fish community diversity. Results are encouraging so that it is possible to better relate flow and ecosystem conditions, and the proposed method can be used to quantify how flow influences river ecosystems.

Chang, Fi-John; Tsai, Wen-Ping; Chen, Hung-kwai; Yam, Rita Sau-Wai; Herricks, Edwin E.

2013-01-01

392

Effects of the radial inflow of gas and galactic fountains on the chemical evolution of M 31  

NASA Astrophysics Data System (ADS)

Context. Galactic fountains and radial gas flows are very important ingredients for modeling the chemical evolution of galactic disks. Aims: Our aim here is to study the effects of galactic fountains and radial gas flows on the chemical evolution of the disk of Andromeda (M 31) galaxy. Methods: We adopt a ballistic method to study the effects of galactic fountains on the chemical enrichment of the M 31 disk by analyzing the landing coordinate of the fountains and the time delay in the pollution of the interstellar gas. To understand the consequences of radial flows, we adopt a very detailed chemical evolution model. Our aim is to study the formation of abundance gradients along the M 31 disk and also compare our results with the Milky Way. Results: We find that the landing coordinate for the fountains in M 31 is no more than 1 kpc from the starting point, thus producing a negligible effect on the chemical evolution of the disk. We find that the delay time in the enrichment process due to fountains is no longer than 100 Myr, and this timescale also produces insignificant effects on the results. Then, we compute the chemical evolution of the M 31 disk with radial gas flows produced by the infall of extragalactic material and fountains. We find that a moderate inside-out formation of the disk, coupled with radial flows of variable speed, can reproduce the observed gradient very well. We also discuss the effects of other parameters, such as a threshold in the gas density for star formation and efficiency of star formation varying with the galactic radius. Conclusions: We conclude that galactic fountains do not affect the chemical evolution of the M 31 disk. Including radial gas flows with an inside-out formation of the disk produces a very good agreement with observations. On the other hand, if radial flows are not considered, one should assume a threshold in the star formation and variable star formation efficiency, besides the inside-out formation to reproduce the data. We conclude that the most important physical processes in creating disk gradients are the inside-out formation and the radial gas flows. More data on abundance gradients both locally and at high redshift are necessary to confirm this conclusion.

Spitoni, E.; Matteucci, F.; Marcon-Uchida, M. M.

2013-03-01

393

Heat Transfer Experiments in the Internal Cooling Passages of a Cooled Radial Turbine Rotor  

NASA Technical Reports Server (NTRS)

An experimental study was conducted (1) to experimentally measure, assess and analyze the heat transfer within the internal cooling configuration of a radial turbine rotor blade and (2) to obtain heat transfer data to evaluate and improve computational fluid dynamics (CFD) procedures and turbulent transport models of internal coolant flows. A 1.15 times scale model of the coolant passages within the NASA LERC High Temperature Radial Turbine was designed, fabricated of Lucite and instrumented for transient beat transfer tests using thin film surface thermocouples and liquid crystals to indicate temperatures. Transient heat transfer tests were conducted for Reynolds numbers of one-fourth, one-half, and equal to the operating Reynolds number for the NASA Turbine. Tests were conducted for stationary and rotating conditions with rotation numbers in the range occurring in the NASA Turbine. Results from the experiments showed the heat transfer characteristics within the coolant passage were affected by rotation. In general, the heat transfer increased and decreased on the sides of the straight radial passages with rotation as previously reported from NASA-HOST-sponsored experiments. The heat transfer in the tri-passage axial flow region adjacent to the blade exit was relatively unaffected by rotation. However, the heat transfer on one surface, in the transitional region between the radial inflow passage and axial, constant radius passages, decreased to approximately 20 percent of the values without rotation. Comparisons with previous 3-D numerical studies indicated regions where the heat transfer characteristics agreed and disagreed with the present experiment.

Johnson, B. V.; Wagner, J. H.

1996-01-01

394

Stem water transport of Lithocarpus edulis, an evergreen oak with radial-porous wood.  

PubMed

The stem water conducting system of an evergreen broad-leaved oak, Lithocarpus edulis (Mak.) Nakai, was investigated. Evergreen broad-leaved oaks (Lithocarpus, Castanopsis, Cyclobalanopsis, Quercus) belonging to the Quercoideae are a major component of Asian monsoon forests, and are characterized by the possession of radial-porous wood. A characteristic of radial-porous wood is the development of aggregate rays between radially oriented files of vessels. We measured the distribution of vessel lumen diameters in a stem cross section and calculated the theoretical water conductivity of the wood. The radial profile of the heat pulse velocity (HPV) was measured for an intact whole tree under field conditions and compared with the theoretical distribution of water conductivity. Soft X-ray photographs of frozen stem sections indicated that most of the vessel lumina were filled with water, including those of vessels more than 20 years old. Even when vessels were relatively wide (lumen diameters > 100 microm), cavitation was negligible. The rate of water uptake from the cut stem base correlated closely with HPV (r = 0.96), and HPV closely reflected the mean volume flow per stem sectional area (SFVS) around the sensor probes. However, the ray tissue sharply inhibited heat transfer, and the positioning of the probes strongly affected the absolute value of HPV. It was also found that HPV more closely reflected the mean sap flow velocity in the vessels than did SFVS. PMID:15574403

Hirose, Shigeki; Kume, Atsushi; Takeuchi, Shinichi; Utsumi, Yasuhiro; Otsuki, Kyoichi; Ogawa, Shigeru

2005-02-01

395

Vertical foliage distribution determines the radial pattern of sap flux density in Picea abies.  

PubMed

Understanding the causes determining the radial pattern of sap flux density is important both for improving knowledge of sapwood functioning and for up-scaling sap flow measurements to canopy transpiration and ecosystem water use. To investigate the anatomical connection between whorls and annual sapwood rings, pruning-induced variation in the radial pattern of sap flux density was monitored with Granier probes in a 35-year-old Picea abies (L.) Karst tree that was pruned from the crown bottom up. Modifications in the radial pattern of sap flux density were quantified by a shape index (SI), which varies with the relative contribution of the outer and inner sapwood to tree transpiration. The SI progressively diminished during bottom up pruning, indicating a significant reduction in sap flow contribution of the inner sapwood. Results suggest that the radial pattern of sap flux density depends mainly on the vertical distribution of foliage in the crown, with lower shaded branches hydraulically connected with inner sapwood and upper branches connected with the outer rings. PMID:18595843

Fiora, Alessandro; Cescatti, Alessandro

2008-09-01

396

Automated gas chromatography  

DOEpatents

An apparatus and process for the continuous, near real-time monitoring of low-level concentrations of organic compounds in a liquid, and, more particularly, a water stream. A small liquid volume of flow from a liquid process stream containing organic compounds is diverted by an automated process to a heated vaporization capillary where the liquid volume is vaporized to a gas that flows to an automated gas chromatograph separation column to chromatographically separate the organic compounds. Organic compounds are detected and the information transmitted to a control system for use in process control. Concentrations of organic compounds less than one part per million are detected in less than one minute.

Mowry, Curtis D. (Albuquerque, NM); Blair, Dianna S. (Albuquerque, NM); Rodacy, Philip J. (Albuquerque, NM); Reber, Stephen D. (Corrales, NM)

1999-01-01

397

The Radial Approach to Selective Carotid Artery Angiogram.  

PubMed

Selective carotid artery angiography via either radial artery was performed in 12 patients, mostly in combination with other diagnostic procedures. No failures to cannulate either the radial or carotid arteries were encountered. Extra-cranial angiography through a radial approach is safe, feasible and comparable to other accepted ports of entry. PMID:10762896

Lewin

1997-04-01

398

Non-linear systems identification using radial basis functions  

Microsoft Academic Search

This paper investigates the identification of discrete-time non-linear systems using radial basis functions. A forward regression algorithm based on an orthogonal decomposition of the regression matrix is employed to select a suitable set of radial basis function centers from a large number of possible candidates and this provides, for the first time, fully automatic selection procedure for identifying parsimonious radial

S. CHEN; S. A. BILLINGS; C. F. N. COWAN; P. M. GRANT

1990-01-01

399

Orthogonal least squares learning algorithm for radial basis function networks  

Microsoft Academic Search

The radial basis function network offers a viable alternative to the two-layer neural network in many applications of signal processing. A common learning algorithm for radial basis function networks is based on first choosing randomly some data points as radial basis function centers and then using singular-value decomposition to solve for the weights of the network. Such a procedure has

S. Chen; C. F. N. Cowan; P.M. Grant

1991-01-01

400

The interaction between two radial jets  

E-print Network

Actual flow exit angle for -10 deg RJR nozzle 12 Table 2 Flow visualization test conditions 17 Table 3 Heat transfer test conditions 29 Table 4 Reattachment locations for each flow type for X&/D& =2. 25 36 NOMENCLATURE A b cp C D E FT FTF g... h i I J k 1 m n Nu P Pw q r R Re S S' St T U V X Y z nozzle exit width specific heat coefficient diameter foil voltage flow type flow type factor gravitational acceleration heat transfer coefficient integer current...

Gruber, Thomas Clifton

2012-06-07

401

Liquid cooled counter flow turbine bucket  

DOEpatents

Means and a method are provided whereby liquid coolant flows radially outward through coolant passages in a liquid cooled turbine bucket under the influence of centrifugal force while in contact with countercurrently flowing coolant vapor such that liquid is entrained in the flow of vapor resulting in an increase in the wetted cooling area of the individual passages.

Dakin, James T. (Schenectady, NY)

1982-09-21

402

Micro-polarimeter for high performance liquid chromatography  

DOEpatents

A micro-polarimeter interfaced with a system for high performance liquid chromatography, for quantitatively analyzing micro and trace amounts of optically active organic molecules, particularly carbohydrates. A flow cell with a narrow bore is connected to a high performance liquid chromatography system. Thin, low birefringence cell windows cover opposite ends of the bore. A focused and polarized laser beam is directed along the longitudinal axis of the bore as an eluent containing the organic molecules is pumped through the cell. The beam is modulated by air gap Faraday rotators for phase sensitive detection to enhance the signal to noise ratio. An analyzer records the beams's direction of polarization after it passes through the cell. Calibration of the liquid chromatography system allows determination of the quantity of organic molecules present from a determination of the degree to which the polarized beam is rotated when it passes through the eluent.

Yeung, Edward E. (Ames, IA); Steenhoek, Larry E. (Wilmington, DE); Woodruff, Steven D. (Morgantown, WV); Kuo, Jeng-Chung (Skokie, IL)

1985-01-01

403

Radial diffusion between coaxial cylinders and surface deactivation of O2(b1Eg+)  

Microsoft Academic Search

The rates for deactivation of singlet oxygen, O2(b1(Sigma) g+), upon collision with pyrex, Teflon, aluminum, copper, and nickel surfaces have been determined in a steady-state flow tube reactor. Numerical and approximate analytic solutions of the radial diffusion equation with coaxial cylindrical boundary conditions are presented to obtain wall deactivation probabilities from observed first order decay rates. The probability for deactivation

Glen P. Perram; Deborah A. Determan; John A. Dorian; Barrett F. Lowe; Tim L. Thompson

1993-01-01

404

Analysis of a radial-outflow reaction turbine concept for geothermal application  

Microsoft Academic Search

The radial-outflow reaction turbine, a pure-reaction turbine designed to improve the conversion efficiency of geothermal energy into electrical power is described. It also has potential as a total-flow turbine for low-temperature water. The principle of incomplete expansion can be used to obtain a reduction in turbine size when the turbine exhausts into a low-pressure condenser. And, by adding this turbine

1978-01-01

405

Thermography of hands after a radial forearm flap has been harvested  

Microsoft Academic Search

To determine the change of blood flow in the hand after radial forearm flap harvest, several studies using thermography or color Doppler ultrasonography have been reported (Iida et al., Ann Plast Surg 49:156, 2002; Suominen and Asko-Seljavaara, Scand J Plast Reconstr Hand Surg 30:307, 1996). One study using Doppler ultrasonography (Iida et al., Ann Plast Surg 49:156, 2002) found reduced

Masamitsu Kuwahara; Satoshi Yurugi; Kumi Mashiba; Hiroshi Iioka; Katsunori Niitsuma; Taichi Noda

2006-01-01

406

A numerical inversion of a the Laplace transform solution to radial dispersion in a porous medium.  

USGS Publications Warehouse

A special form of the numerical inversion of the Laplace transform described by Stehfest (1970) is applied to the transformed solution of dispersion in a radial flow system in a porous medium. The inversion is extremely simple to use because the weighting coefficients depend only on the number of terms used in the computation and not upon the transform solution as required by most numerical inversion techniques.-from Authors

Moench, A.F.; Ogata, A.

1981-01-01

407

Chromatography (LC/GC) Online  

NSDL National Science Digital Library

Chromatography (LC/GC) Online magazine is a very good source for relatively short articles about fundamental chromatographic issues as well as applications. The content is appropriate for introductory analytical courses (e.g. quant) and for instrumental analysis courses.

2011-05-23

408

Novel approaches to ionic chromatography  

SciTech Connect

Research during this reporting period, continued on ionic chromatography. Major progress has been made towards on-line on-demand generation of ultrapure chemicals by electrochemical means. The concentration of the generated material is governed electrochemically.

Dasgupta, P.K.

1990-11-01

409

Nonlinear radial oscillations of neutron stars  

E-print Network

The effects of nonlinear oscillations in compact stars are attracting considerable current interest. In order to study such phenomena in the framework of fully nonlinear general relativity, highly accurate numerical studies are required. We present a numerical scheme specifically tailored for studies, based on formulating the time evolution in terms of deviations from a stationary equilibrium configuration. Using this technique, we investigate nonlinear effects associated with radial oscillations of neutron stars for a wide range of amplitudes. In particular, we discuss mode coupling due to nonlinear interactions, the occurrence of resonance phenomena, shock formation near the stellar surface as well as the capacity of nonlinearities to stabilize perturbatively unstable neutron star models.

Michael Gabler; Ulrich Sperhake; Nils Andersson

2009-06-17

410

Radial heat transfer from a moving plasma  

E-print Network

to design reactors. A good review of plasma jet technology has been prepared by Dennis? Smith, Gates, ard Bord (I). In th s research? the total heat flux in the radial direction was measured experimertaily from a moving plasma or plasma jet with a water... the advances made 'ri plasma generatior technology, John and Bade (4) suggested that the convective heat losses from a plasma gas stre am to the walls of the conf ining chamber may be represented by the equatior 0. 023 0 (Hs ? H ) qc = prO 60 Reo ~ 20 (II-2...

Johnson, James Randall

2012-06-07

411

Compact solitons, bags, and radial excitations  

SciTech Connect

Compact nodal soliton solutions for a Dirac equation with fractional nonlinearity are studied. This model is a natural field-theoretical generalization of the MIT bag model. In the limit where the power nonlinearity is arbitrarily small, the exact nodal solutions are obtained and shown to be different from the corresponding radial excitations in the MIT bag model. The complete energy spectrum is also different, except for massless confined fields in 1+1 dimensions. Finally the nonexistence of spherical solitons with negative parity is established.

Mathieu, P.

1985-12-15

412

Use of a traveling magnetic field in VGF growth: Flow reversal and resulting dopant distribution  

Microsoft Academic Search

The melt flow in a model of a vertical gradient freeze facility under the action of a traveling magnetic field (TMF) is studied numerically. The radial temperature gradient over a concave solidification interface drives a radially converging flow which may cause an undesirable dopant concentration peak on the axis. We study the characteristics of such a flow for parameters beyond

Ilmars Grants; Gunter Gerbeth

2008-01-01

413

High energy density plasmas generated by radial foil explosions  

NASA Astrophysics Data System (ADS)

High energy density (HED) plasmas, produced by diverse techniques, such as lasers or pulsed power generators, can help scientists to better understand extreme states of matter as well as astrophysical phenomena. While fast Z-pinches are the most common approach to generating HED plasmas in the pulsed power community, radial foil configurations can yield plasma pressures on the order of 0.5 Mbar on a 1 MA, 100 ns current rise time generator, similar to wire array configurations producing Z-pinches. In this experimental setup, a thin metallic foil stretched onto a circular anode connects to a very small 'pin' cathode at the center. Radial currents flow in the foil then down the pin cathode, thereby generating an axi-symmetric toroidal magnetic field under the foil. Initial experimental results (Gourdain et al 2010 Phys. Plasmas 17 012706) showed that the foil current interacts with this field and the resulting J × B force lifts the foil upward. Very rapidly the foil plasma turns into a bubble-shaped cavity above the central pin, and that bubble expands at 300 km s-1, until instabilities destroy the axial symmetry, bursting the bubble open. This paper complements these initial results by using time-integrated x-ray pin-hole cameras and a focusing spectrometer with spatial resolution. In addition to laser interferometry, these new data help to provide a better estimate of the plasma electron density inside the bubble, above 1020 cm-3, and of the electron temperature, between 300 and 400 eV inside the central plasma column. We also discovered the presence of 'bright' spots in the plasma, with densities larger than 5 × 1021 electrons cm-3 and temperatures above 1 keV. Finally laser interferometry gives a precise mapping of the initial plasma jet and bubble areal densities.

Gourdain, P.-A.; Blesener, I. C.; Greenly, J. B.; Hammer, D. A.; Knapp, P. F.; Kusse, B. R.; Pikuz, S. A.; Shelkovenko, T. C.

2010-05-01

414

Adsorption chromatography of alkaloids of fumaria officinalis  

Microsoft Academic Search

Seven alkaloids of Fumaria officinalis, difficult to separate by partition chromatography and countercurrent distribution, were separated by column chromatography using silica gel developed with mixtures of propanol or methanol with nonpolar solvents. Suitable solvent systems for column chromatography were chosen on the basis of thin layer chromatography data.

W. Golkiewicz; T. Wawrzynowicz

1970-01-01

415

Comparing radial and femoral access for coronary angiography and interventions.  

PubMed

Cardiac catheterization and coronary intervention via the radial approach is increasingly adopted as the preferred vascular access to avoid transfemoral vascular complications. Recent clinical trials have confirmed that radial access reduces vascular complications and local bleeding with similar procedural efficacy. Transradial access has inherent technical challenges, including smaller vessel size of the radial artery, arterial spasm and tortuosity involving the radial and subclavian arteries, which may undermine the procedural success of this approach. A number of strategies have been reported to minimize complications of radial access, including the use of hydrophilic introducer sheaths and smaller sheath sizes, administration of nitroglycerin and unfractionated heparin during the procedure, patent hemostasis of the radial artery and careful patient selection. Operators experienced in transradial percutaneous coronary intervention can achieve comparable clinical outcomes to the transfemoral approach and minimize vascular complications. Radial artery access is likely to become widely accepted as the preferred percutaneous coronary intervention approach. PMID:24236557

Hsieh, Victar; Jolly, Sanjit

2013-03-01

416

A radial transmission line material measurement apparatus  

SciTech Connect

A radial transmission line material measurement sample apparatus (sample holder, offset short standards, measurement software, and instrumentation) is described which has been proposed, analyzed, designed, constructed, and tested. The purpose of the apparatus is to obtain accurate surface impedance measurements of lossy, possibly anisotropic, samples at low and intermediate frequencies (vhf and low uhf). The samples typically take the form of sections of the material coatings on conducting objects. Such measurements thus provide the key input data for predictive numerical scattering codes. Prediction of the sample surface impedance from the coaxial input impedance measurement is carried out by two techniques. The first is an analytical model for the coaxial-to-radial transmission line junction. The second is an empirical determination of the bilinear transformation model of the junction by the measurement of three full standards. The standards take the form of three offset shorts (and an additional lossy Salisbury load), which have also been constructed. The accuracy achievable with the device appears to be near one percent.

Warne, L.K.; Moyer, R.D.; Koontz, T.E.; Morris, M.E.

1993-05-01

417

Calibration of cameras with radially symmetric distortion.  

PubMed

We present algorithms for plane-based calibration of general radially distorted cameras. By this, we understand cameras that have a distortion center and an optical axis such that the projection rays of pixels lying on a circle centered on the distortion center form a right viewing cone centered on the optical axis. The camera is said to have a single viewpoint (SVP) if all such viewing cones have the same apex (the optical center); otherwise, we speak of NSVP cases. This model encompasses the classical radial distortion model [5], fisheyes, and most central or noncentral catadioptric cameras. Calibration consists in the estimation of the distortion center, the opening angles of all viewing cones, and their optical centers. We present two approaches of computing a full calibration from dense correspondences of a single or multiple planes with known euclidean structure. The first one is based on a geometric constraint linking viewing cones and their intersections with the calibration plane (conic sections). The second approach is a homography-based method. Experiments using simulated and a broad variety of real cameras show great stability. Furthermore, we provide a comparison with Hartley-Kang's algorithm [12], which, however, cannot handle such a broad variety of camera configurations, showing similar performance. PMID:19574618

Tardif, Jean-Philippe; Sturm, Peter; Trudeau, Martin; Roy, Sébastien

2009-09-01

418

Stability of trailing vortices with radial stratification  

NASA Astrophysics Data System (ADS)

We look at the effects of the radial density stratification on the stability of the q-vortex, a commonly accepted model for aircraft trailing vortices. It has been demonstrated that the 2D Lamb--Oseen vortex develops a Rayleigh--Taylor instability when its core is heavier than the surrounding fluid (Joly, Fontane & Chassaing 2005, Sipp et al 2005). The underlying mechanism relies on baroclinic vorticity generation due to any misalignment between the density gradient and the centripetal acceleration field. The instability is triggered provided that the density decreases radially somewhere in the vortex core. This mechanism is also active in the 3D trailing vortex and affects its stability characteristics due to the addition of an axial component in the acceleration field. We show that the unstable center modes of the homogeneous case (Fabre & Jacquin 2004) are promoted in a q-vortex with a heavy core. Their growth rate increases while their m-spiral structure is preserved. For an Atwood number At=0.5, their predicted growth rate can be ten times the ones found in the homogeneous case. Furthermore, the unstable domain is extended far beyond the neutral curve in the homogeneous case, with unstable modes observed for Swirl numbers up to q=5. It is argued here that corresponding density perturbations could eventually lead to the development of new and original strategies to decrease the lifespan of aircraft trailing vortices and greatly reduce their unwanted side-effects on contrails persistence and air traffic regulations.

Fontane, Jerome; Joly, Laurent; Audouin, Auriane

2011-11-01

419

Behavior of a Radial Time Projection Chamber  

NASA Astrophysics Data System (ADS)

Using Gas Electron Multiplying (GEM) foils for amplification, the detector allows for three-dimensional representations of particle tracks through two half cylinders filled with gas. Developed for the Bound Nucleon Structure (BONUS) experiment at Jefferson Lab, the RTPC allows experimenters to study the quark composition of the neutron by scattering electrons from deuterium nuclei. The defining feature of the detector is that it allows for a complete view of the interaction of the electron and target gas, including the protons left over after a reaction on the neutron. This experiment seeks to understand the efficiency of the detector and its amplification (signal strength for a given ionization, as a function of detector gas and high voltage), by making a measurement of the amount of energy deposited in the chamber per unit length from cosmic radiation. In order to test each half of the Radial Time Projection Chamber we use an 85% Helium and 15% Dimethyl Ether (85/15 HeDME) and an 80/20 HeDME at optimal voltages to detect cosmic particles. The detector takes an electronic snapshot of the incident particle by examining the charge deposited as a function of time. The importance of this technology should not be underestimated. Radial Time Projection Chambers could, in some applications, replace current Time Projection Chambers and Wire Chambers.

Bradshaw, Peter

2006-10-01

420

Surface diffusion in reversed-phase liquid chromatography  

SciTech Connect

More than 40 years ago, Giddings pointed out in 'Dynamics of Chromatography' that surface diffusion should become an important research topic in the kinetics of chromatographic phenomena. However, few studies on surface diffusion in adsorbents used in chromatography were published since then. Most scientists use ordinary rate equations to study mass transfer kinetics in chromatography. They take no account of surface diffusion and overlook the significant contributions of this mass transfer process to chromatographic behavior and to column efficiency at high mobile phase flow rate. Only recently did the significance of surface diffusion in separation processes begin to be recognized in connection with the development of new techniques of fast flow, high efficiency chromatography. In this review, we revisit the reports on experimental data on surface diffusion and introduce a surface-restricted molecular diffusion model, derived as a first approximation for the mechanism of surface diffusion, on the basis of the absolute rate theory. We also explain how this model accounts for many intrinsic characteristics of surface diffusion that cannot properly be explained by the conventional models of surface diffusion.

Miyabe, Kanji [Toyama University, Japan; Guiochon, Georges A [ORNL

2010-01-01

421

FORTRAN program for predicting off-design performance of radial-inflow turbines  

NASA Technical Reports Server (NTRS)

The FORTRAN IV program uses a one-dimensional solution of flow conditions through the turbine along the mean streamline. The program inputs needed are the design-point requirements and turbine geometry. The output includes performance and velocity-diagram parameters over a range of speed and pressure ratio. Computed performance is compared with the experimental data from two radial-inflow turbines and with the performance calculated by a previous computer program. The flow equations, program listing, and input and output for a sample problem are given.

Wasserbauer, C. A.; Glassman, A. J.

1975-01-01

422

Application of high-performance liquid chromatography-nuclear magnetic resonance coupling to the identification of limonoids from mahogany tree (Switenia macrophylla, Meliaceae) by stopped-flow 1D and 2D NMR spectroscopy.  

PubMed

Separation and characterization of limonoids from Switenia macrophylla (Meliaceae) by HPLC-NMR technique has been described. Analyses were carried out using reversed-phase gradient HPLC elution coupled to NMR (600 MHz) spectrometer in stopped-flow mode. Separated peaks were collected into an interface unit prior to NMR measurements, which were performed with suppression of solvent signals by shaped pulses sequences. Structure elucidation of the limonoids was attained by data obtained from 1H NMR, TOCSY, gHSQC and gHMBC spectra without conventional isolation that is usually applied in natural products studies. PMID:16904679

Schefer, Alexandre B; Braumann, Ulrich; Tseng, Li-Hong; Spraul, Manfred; Soares, Marisi G; Fernandes, João B; da Silva, Maria F G F; Vieira, Paulo C; Ferreira, Antonio G

2006-09-22

423

An Experimental Study of Wave Dispersion in a Differentially Heated Rotating Fluid Annulus with a Radially Sloping Bottom  

Microsoft Academic Search

Baroclinic waves in a rotating fluid annulus with a downward sloping bottom in the radial direction and with a free upper surface have been studied experimentally. Dispersive wave flows due to the effect of the depth variation (the topographic beta-effect) have been observed and analyzed with special attention to the interactions among the wave components. The internal structure, the upper

Katsumi TAMAKI; Kazuo UKAJI

2003-01-01

424

Effect of blade wrap angle on efficiency and noise of small radial fan impellers—A computational and experimental study  

NASA Astrophysics Data System (ADS)

Radial impellers have several technical applications. Regarding their aerodynamic performance, they are well optimized nowadays, but this is in general not true regarding acoustics. This work was therefore concerned with analyzing the flow structures inside isolated radial impellers together with the far-field sound radiated from them in order to optimize the aerodynamic and acoustic performance. Both numerical and experimental techniques were applied in order to study the effect of varying wrap angle and otherwise identical geometric configuration on aerodynamics and acoustics of the radial impellers. The results give a detailed insight into the processes leading to sound generation in radial impellers. Measurements were performed using laser Doppler anemometry for the flow field and microphone measurements to analyze the radiated noise. In addition, unsteady aerodynamic simulations were carried out to calculate the compressible flow field. An acoustic analogy was employed to compute far-field noise. Finally, the phenomena responsible for tonal noise and the role of the wrap angle could be identified. Using this knowledge, design guidelines are given to optimize the impeller with respect to the radiated noise. This work shows that improved aerodynamic efficiency for isolated impellers does not automatically lead to a smaller flow-induced sound radiation.

Scheit, C.; Karic, B.; Becker, S.

2012-02-01

425

Fabricating Radial Groove Gratings Using Projection Photolithography  

NASA Technical Reports Server (NTRS)

Projection photolithography has been used as a fabrication method for radial grove gratings. Use of photolithographic method for diffraction grating fabrication represents the most significant breakthrough in grating technology in the last 60 years, since the introduction of holographic written gratings. Unlike traditional methods utilized for grating fabrication, this method has the advantage of producing complex diffractive groove contours that can be designed at pixel-by-pixel level, with pixel size currently at the level of 45 45 nm. Typical placement accuracy of the grating pixels is 10 nm over 30 nm. It is far superior to holographic, mechanically ruled or direct e-beam written gratings and results in high spatial coherence and low spectral cross-talk. Due to the smooth surface produced by reactive ion etch, such gratings have a low level of randomly scattered light. Also, due to high fidelity and good surface roughness, this method is ideally suited for fabrication of radial groove gratings. The projection mask is created using a laser writer. A single crystal silicon wafer is coated with photoresist, and then the projection mask, with its layer of photoresist, is exposed for patterning in a stepper or scanner. To develop the photoresist, the fabricator either removes the exposed areas (positive resist) of the unexposed areas (negative resist). Next, the patterned and developed photoresist silicon substrate is subjected to reactive ion etching. After this step, the substrate is cleaned. The projection mask is fabricated according to electronic design files that may be generated in GDS file format using any suitable CAD (computer-aided design) or other software program. Radial groove gratings in off-axis grazing angle of incidence mount are of special interest for x-ray spectroscopy, as they allow achieving higher spectral resolution for the same grating area and have lower alignment tolerances than traditional in-plane grating scheme. This is especially critical for NASA Constellation- X project that will utilize hundreds of gratings all of which need to be precisely aligned for x-ray observation of space.

Iazikov, Dmitri; Mossberg, Thomas W.

2009-01-01

426

Aerodynamically induced radial forces in a centrifugal gas compressor: Part 2 -- Computational investigation  

SciTech Connect

Radial loads and direction of a centrifugal gas compressor containing a high specific speed mixed flow impeller and a single tongue volute were determined both experimentally and computationally at both design and off-design conditions. The experimental methodology was developed in conjunction with a traditional ASME PTC-10 closed-loop test to determine radial load and direction. The experimental study is detailed in Part 1 of this paper (Moore and Flathers, 1998). The computational method employs a commercially available, fully three-dimensional viscous code to analyze the impeller and the volute interaction. An uncoupled scheme was initially used where the impeller and volute were analyzed as separate models using a common vaneless diffuser geometry. The two calculations were then repeated until the boundary conditions at a chosen location in the common vaneless diffuser were nearly the same. Subsequently, a coupled scheme was used where the entire stage geometry was analyzed in one calculation, thus eliminating the need for manual iteration of the two independent calculations. In addition to radial load and direction information, this computational procedure also provided aerodynamic stage performance. The effect of impeller front face and rear face cavities was also quantified. The paper will discuss computational procedures, including grid generation and boundary conditions, as well as comparisons of the various computational schemes to experiment. The results of this study will show the limitations and benefits of Computational Fluid Dynamics (CFD) for determination of radial load, direction, and aerodynamic stage performance.

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

1999-10-01

427

Transpiration Induces Radial Turgor Pressure Gradients in Wheat and Maize Roots.  

PubMed Central

Previous studies have shown both the presence and the absence of radial turgor and osmotic pressure gradients across the cortex of roots. In this work, gradients were sought in the roots of wheat (Triticum aestivum) and maize (Zea mays) under conditions in which transpiration flux across the root was varied This was done by altering the relative humidity above the plant, by excising the root, or by using plants in which the leaves were too young to transpire. Roots of different ages (4-65 d) were studied and radial profiles at different distances from the tip (5-30 mm) were measured. In both species, gradients of turgor and osmotic pressure (increasing inward) were found under transpiring conditions but not when transpiration was inhibited. The presence of radial turgor and osmotic pressure gradients, and the behavior of the gradient when transpiration is interrupted, indicate that active membrane transport or radial solvent drag may play an important role in the distribution of solutes across the root cortex in transpiring plants. Contrary to the conventional view, the flow of water and solutes across the symplastic pathway through the plasmodesmata cannot be inwardly directed under transpiring conditions. PMID:12231957

Rygol, J.; Pritchard, J.; Zhu, J. J.; Tomos, A. D.; Zimmermann, U.

1993-01-01

428

On the Origin of Near-Radial Magnetic Fields in the Heliosphere: Numerical Simulations  

NASA Technical Reports Server (NTRS)

Deviations from the direction of the "Parker spiral" can be found in in situ measurements of the interplanetary magnetic field on essentially all scales. One intriguing subset is the intervals of near-radial magnetic field, lasting for many hours. Some such intervals are obviously associated with coronal mass ejections, while others appear to be embedded within the ambient solar wind. Most occur on declining speed profiles, such that, when mapped back to the Sun, an entire radial field interval appears to have been launched at approximately the same time. It has been proposed that these events are the result of abrupt, semipermanent speed decreases on these field lines close to the Sun, and that such speed changes might be due to interchange reconnection. In this study, we use a three-dimensional, time-dependent magnetohydrodynamic model to assess to what extent this can account for near-radial magnetic fields observed relatively far out in the heliosphere. We find that sudden speed drops on the trailing portions of high-speed flows can produce strongly underwound (that is near radial) field lines in the heliosphere, although significantly larger speed gradients are required than are typically observed. Moreover, the simulations also reproduce the decreases in density, temperature, and magnetic field strength that are also commonly observed within these events. The question of what produces the abrupt speed drops remains to be answered.

Mikic, Zoran; Riley, Pete; Gosling, T. J.

2007-01-01

429

Initial experiments using radial foils on the Cornell Beam Research Accelerator pulsed power generator  

NASA Astrophysics Data System (ADS)

A novel technique involving radial foil explosions can produce high energy density plasmas. A current flows radially inward in a 5 ?m thin aluminum foil from a circular anode, which contacts the foil on its outer rim, to the cathode, which connects to the foil at its geometrical center. When using small "pin" cathodes (˜1 mm in diameter) on a medium size pulsed-current generator such as the Cornell Beam Research Accelerator, the central magnetic field approaches 400 T, yielding magnetic pressures larger than 0.5 Mbar. While the dynamics is similar to radial wire arrays, radial foil discharges have very distinct characteristics. First a plasma jet forms, with densities near 5×1018 cm-3. J×B forces lift the foil upward with velocities of ˜200 km/s. A plasma bubble with electron densities superior to 5×1019 cm-3 then develops, surrounding a central plasma column, carrying most of the cathode current. X-ray bursts coming from the center of this column were recorded at 1 keV photon energy. As the magnetic bubble explodes, ballistic plasma projectiles form and escape with velocities exceeding 300 km/s. Laser shadowgraphy and interferometry, gated extreme ultraviolet imaging and miniature Bdot probes are used to investigate the magnetohydrodynamics properties of such configurations.

Gourdain, P.-A.; Blesener, I. C.; Greenly, J. B.; Hammer, D. A.; Knapp, P. F.; Kusse, B. R.; Schrafel, P. C.

2010-01-01

430

Initial experiments using radial foils on the Cornell Beam Research Accelerator pulsed power generator  

SciTech Connect

A novel technique involving radial foil explosions can produce high energy density plasmas. A current flows radially inward in a 5 mum thin aluminum foil from a circular anode, which contacts the foil on its outer rim, to the cathode, which connects to the foil at its geometrical center. When using small 'pin' cathodes (approx1 mm in diameter) on a medium size pulsed-current generator such as the Cornell Beam Research Accelerator, the central magnetic field approaches 400 T, yielding magnetic pressures larger than 0.5 Mbar. While the dynamics is similar to radial wire arrays, radial foil discharges have very distinct characteristics. First a plasma jet forms, with densities near 5x10{sup 18} cm{sup -3}. JxB forces lift the foil upward with velocities of approx200 km/s. A plasma bubble with electron densities superior to 5x10{sup 19} cm{sup -3} then develops, surrounding a central plasma column, carrying most of the cathode current. X-ray bursts coming from the center of this column were recorded at 1 keV photon energy. As the magnetic bubble explodes, ballistic plasma projectiles form and escape with velocities exceeding 300 km/s. Laser shadowgraphy and interferometry, gated extreme ultraviolet imaging and miniature Bdot probes are used to investigate the magnetohydrodynamics properties of such configurations.

Gourdain, P.-A.; Blesener, I. C.; Greenly, J. B.; Hammer, D. A.; Knapp, P. F.; Kusse, B. R.; Schrafel, P. C. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States)

2010-01-15

431

Transpiration Induces Radial Turgor Pressure Gradients in Wheat and Maize Roots.  

PubMed

Previous studies have shown both the presence and the absence of radial turgor and osmotic pressure gradients across the cortex of roots. In this work, gradients were sought in the roots of wheat (Triticum aestivum) and maize (Zea mays) under conditions in which transpiration flux across the root was varied This was done by altering the relative humidity above the plant, by excising the root, or by using plants in which the leaves were too young to transpire. Roots of different ages (4-65 d) were studied and radial profiles at different distances from the tip (5-30 mm) were measured. In both species, gradients of turgor and osmotic pressure (increasing inward) were found under transpiring conditions but not when transpiration was inhibited. The presence of radial turgor and osmotic pressure gradients, and the behavior of the gradient when transpiration is interrupted, indicate that active membrane transport or radial solvent drag may play an important role in the distribution of solutes across the root cortex in transpiring plants. Contrary to the conventional view, the flow of water and solutes across the symplastic pathway through the plasmodesmata cannot be inwardly directed under transpiring conditions. PMID:12231957

Rygol, J.; Pritchard, J.; Zhu, J. J.; Tomos, A. D.; Zimmermann, U.

1993-10-01

432

Low thermal mass liquid chromatography.  

PubMed

A novel technique, low thermal mass liquid chromatography (LTMLC), is introduced in this study. The use of an LTM assembly that utilizes the principle of resistive wire heating and a temperature sensor to accurately deliver unprecedented heating (up to 1800 degrees C/min) or cooling (100 to approximately 200 degrees C/min) rates is reported. With the use of packed microcolumns (<0.5 mm i.d.), essentially instantaneous heat transfer from the assembly to the mobile phase was obtained. A systematic investigation was conducted to study the performance of the LTMLC technique. Both isocratic and gradient mobile phase conditions were used. For temperature control, isothermal, temperature-increasing, and temperature-decreasing gradients were applied. Three model mixtures, two of which containing neutral and acidic analytes and the other containing neutral, acidic, and basic analytes, were used to study the effect of temperature on elution time, resolution, column efficiency, and selectivity. It was found that the LTMLC experimental setup delivered reliable temperature control, as evidenced by linear van't Hoff plots for neutral and acidic compounds. The effect of temperature on the elution of basic analytes yielded nonlinear van't Hoff plots, explaining the dramatic selectivity changes observed for bases with changes in column temperature. Column efficiency generally increased with the increase in column temperature in the range of 25 to approximately 75 degrees C and decreased in the range of 75 to approximately 150 degrees C at a fixed column flow rate (3 microL/min), when extra column band broadening was taken into account. The increase in efficiency upon the increase in column temperature in the low temperature range was mainly due to the decreased mass transfer term resulting from increased analyte diffusivity. However, under even higher temperatures, the longitudinal diffusion dominated band broadening, explaining the decrease in column efficiency upon a further increase in column temperature. Resolution and selectivity decreased at elevated temperature for neutral and acidic compounds. For mixtures that contain bases, improved resolution was obtained by simultaneously tuning temperature and solvent programming. In addition to heating ability, LTMLC also demonstrated reliable cooling capability, allowing performance of oscillated or cycled temperature programming for fine-tuning the separation of critical band pairs for the first time. Finally, ultrafast reproducible LTMLC was also demonstrated, showing the potential of utilization of this technology for fast and ultrafast separations. PMID:19140670

Gu, Binghe; Cortes, Hernan; Luong, Jim; Pursch, Matthias; Eckerle, Patric; Mustacich, Robert

2009-02-15

433

Sample injector for high pressure liquid chromatography  

DOEpatents

Apparatus and method for driving a sample, having a well-defined volume, under pressure into a chromatography column. A conventional high pressure sampling valve is replaced by a sample injector composed of a pair of injector components connected in series to a common junction. The injector components are containers of porous dielectric material constructed so as to provide for electroosmotic flow of a sample into the junction. At an appropriate time, a pressure pulse from a high pressure source, that can be an electrokinetic pump, connected to the common junction, drives a portion of the sample, whose size is determined by the dead volume of the common junction, into the chromatographic column for subsequent separation and analysis. The apparatus can be fabricated on a substrate for microanalytical applications.

Paul, Phillip H. (Livermore, CA); Arnold, Don W. (Livermore, CA); Neyer, David W. (Castro Valley, CA)

2001-01-01

434

Radial particle distributions in PARMILA simulation beams  

SciTech Connect

The estimation of beam spill in particle accelerators is becoming of greater importance as higher current designs are being funded. To the present, no numerical method for predicting beam-spill has been available. In this paper, we present an approach to the loss-estimation problem that uses probability distributions fitted to particle-simulation beams. The properties of the PARMILA code's radial particle distribution are discussed, and a broad class of probability distributions are examined to check their ability to fit it. The possibility that the PARMILA distribution is a mixture is discussed, and a fitting distribution consisting of a mixture of two generalized gamma distributions is found. An efficient algorithm to accomplish the fit is presented. Examples of the relative prediction of beam spill are given. 26 references, 18 figures, 1 table.

Boicourt, G.P.

1984-03-01

435

RV: Radial Components of Observer's Velocity  

NASA Astrophysics Data System (ADS)

The RV program produces a report listing the components, in a given direction, of the observer's velocity on a given date. This allows an observed radial velocity to be referred to an appropriate standard of rest -- typically either the Sun or an LSR. As a secondary function, RV computes light time components to the Sun, thus allowing the times of phenomena observed from a terrestrial observatory to be referred to a heliocentric frame of reference. n.b. It will of course, in addition, be necessary to express the observations in the appropriate timescale as well as applying light time corrections. In particular, it is likely that an observed UTC will need to be converted to TDB as well as being corrected to the Sun.) RV is distributed with the Starlink software collection (ascl:1110.012) and uses SLALIB (ascl:1403.025).

Wallace, Patrick T.; Clayton, Chris A.

2014-06-01

436

Precise radial velocities in the near infrared  

NASA Astrophysics Data System (ADS)

Since the first detection of a planet outside our Solar System byWolszczan & Frail (1992), over 500 exoplanets have been found to date2, none of which resemble the Earth. Most of these planets were discovered by measuring the radial velocity (hereafter, RV) of the host star, which wobbles under the gravitational influence of any existing planetary companions. However, this method has yet to achieve the sub-m/s precision necessary to detect an Earth-mass planet in the Habitable Zone (the region around a star that can support liquid water; hereafter, HZ) (Kasting et al. 1993) around a Solar-type star. Even though Kepler (Borucki et al. 2010) has announced several Earth-sized HZ candidates, these targets will be exceptionally difficult to confirm with current astrophysical spectrographs (Borucki et al. 2011). The fastest way to discover and confirm potentiallyhabitable Earth-mass planets is to observe stars with lower masses - in particular, late M dwarfs. While M dwarfs are readily abundant, comprising some 70% of the local stellar population, their low optical luminosity presents a formidable challenge to current optical RV instruments. By observing in the near-infrared (hereafter, NIR), where the flux from M dwarfs peaks, we can potentially reach low RV precisions with significantly less telescope time than would be required by a comparable optical instrument. However, NIR precision RV measurements are a relatively new idea and replete with challenges: IR arrays, unlike CCDs, are sensitive to the thermal background; modal noise is a bigger issue in the NIR than in the optical; and the NIR currently lacks the calibration sources like the very successful thorium-argon (hereafter, ThAr) hollow-cathode lamp and Iodine gas cell of the optical. The PSU Pathfinder (hereafter, Pathfinder) was designed to explore these technical issues with the intention of mitigating these problems for future NIR high-resolution spectrographs, such as the Habitable-Zone Planet Finder (HZPF) (Mahadevan et al. 2010), and forms the core of my dissertation. I have investigated and quantified several aspects of making precision radial velocity measurements in the NIR using Pathfinder. Between 2006 and 2008, I made precise measurements of the Earth's rotational velocity with respect to the solar spectrum, with which we were able to achieve precisions of less than 10 m/s. In late 2008 and 2009, I worked on optimizing the spectrograph and reduction code in preparation for our first on-sky tests. I also began characterizing a new calibration source for the NIR, the emission spectrum of a uranium-neon hollow-cathode lamp. During 2010, Pathfinder saw first light at the Hobby-Eberly Telescope (hereafter, HET), where we observed almost a dozen radial velocity standard stars and bright planet-hosting stars. Using uraniumneon as a calibration source, we were able to achieve a precision of 20 m/s in the Y band. In collaboration with Colorado University and the National Institute for Standards and Technology (NIST), we fed Pathfinder with a laser frequency comb, and were able to achieve precisions of less than 5 m/s in the H band. These are some of the highestprecision radial velocity measurements in the Y and H bands to date, and represent an enormous advancement in our ability to make precision measurements in the NIR.

Redman, Stephen L.

437

Radial diffusion of Io-injected plasma  

NASA Technical Reports Server (NTRS)

The paper reexamines the problem of particle injection by Io and subsequent radial diffusion by flux tube interchange using a proper phase space density formulation. The mathematical formalism is developed, and the theoretical results are compared with the observations, taking into account the pitch angle and energy coverage of the detector on Pioneer 10. Two objectives are pursued: (1) to test the hypothesis of Siscoe and Chen (1977) that Io is the source for all of the plasma observed by Frank et al. (1976) inside 10 R(J); and (2) to describe a simple but flexible method intended to analyze the observations of any other plasma instrument flown through the inner Jovian magnetosphere, e.g., those on Voyager 1 and 2 and Galileo.

Goertz, C. K.; Thomsen, M. F.

1979-01-01

438

Transit Detection of Radial Velocity Planets  

E-print Network

The orbital parameters of extra-solar planets have a significant impact on the probability that the planet will transit the host star. This was recently demonstrated by the transit detection of HD 17156b whose favourable eccentricity and argument of periastron dramatically increased its transit likelihood. We present a study which provides a quantitative analysis of how these two orbital parameters effect the geometric transit probability as a function of period. Further, we apply these results to known radial velocity planets and show that there are unexpectedly high transit probabilities for planets at relatively long periods. For a photometric monitoring campaign which aims to determine if the planet indeed transits, we calculate the significance of a null result and the subsequent constraints that may be applied to orbital parameters.

Stephen R. Kane; Kaspar von Braun

2008-06-30

439

Radial propagation of geodesic acoustic modes  

NASA Astrophysics Data System (ADS)

The GAM group velocity is estimated from the ratio of the radial free energy flux to the total free energy applying gyrokinetic and two-fluid theory. This method is much more robust than approaches that calculate the group velocity directly and can be generalized to include additional physics, e.g., magnetic geometry. The results are verified with the gyrokinetic code GYRO [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)], the two-fluid code NLET [K. Hallatschek and A. Zeiler, Phys. Plasmas 7, 2554 (2000)], and analytical calculations. GAM propagation must be kept in mind when discussing the windows of GAM activity observed experimentally and the match between linear theory and experimental GAM frequencies.

Hager, Robert; Hallatschek, Klaus

2009-07-01

440

Radial propagation of geodesic acoustic modes  

SciTech Connect

The GAM group velocity is estimated from the ratio of the radial free energy flux to the total free energy applying gyrokinetic and two-fluid theory. This method is much more robust than approaches that calculate the group velocity directly and can be generalized to include additional physics, e.g., magnetic geometry. The results are verified with the gyrokinetic code GYRO[J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)], the two-fluid code NLET[K. Hallatschek and A. Zeiler, Phys. Plasmas 7, 2554 (2000)], and analytical calculations. GAM propagation must be kept in mind when discussing the windows of GAM activity observed experimentally and the match between linear theory and experimental GAM frequencies.

Hager, Robert; Hallatschek, Klaus [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching (Germany)

2009-07-15