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1

Are axial and radial flow chromatography different?  

PubMed

Radial flow chromatography can be a solution for scaling up a packed bed chromatographic process to larger processing volumes. In this study we compared axial and radial flow affinity chromatography both experimentally and theoretically. We used an axial flow column and a miniaturized radial flow column with a ratio of 1.8 between outer and inner surface area, both with a bed height of 5 cm. The columns were packed with affinity resin to adsorb BSA. The average velocity in the columns was set equal. No difference in performance between the two columns could be observed. To gain more insight into the design of a radial flow column, the velocity profile and resin distribution in the radial flow column were calculated. Using mathematical models we found that the breakthrough performance of radial flow chromatography is very similar to axial flow when the ratio between outer and inner radius of the radial flow column is around 2. When this ratio is increased, differences become more apparent, but remain small. However, the ratio does have a significant influence on the velocity profile inside the resin bed, which directly influences the pressure drop and potentially resin compression, especially at higher values for this ratio. The choice between axial and radial flow will be based on cost price, footprint and packing characteristics. For small-scale processes, axial flow chromatography is probably the best choice, for resin volumes of at least several tens of litres, radial flow chromatography may be preferable. PMID:23228917

Besselink, Tamara; van der Padt, Albert; Janssen, Anja E M; Boom, Remko M

2012-11-19

2

Zonal Rate Model for Axial and Radial Flow Membrane Chromatography. Part I: Knowledge Transfer Across Operating Conditions and Scales  

PubMed Central

The zonal rate model (ZRM) has previously been applied for analyzing the performance of axial flow membrane chromatography capsules by independently determining the impacts of flow and binding related non-idealities on measured breakthrough curves. In the present study, the ZRM is extended to radial flow configurations, which are commonly used at larger scales. The axial flow XT5 capsule and the radial flow XT140 capsule from Pall are rigorously analyzed under binding and non-binding conditions with bovine serum albumin (BSA) as test molecule. The binding data of this molecule is much better reproduced by the spreading model, which hypothesizes different binding orientations, than by the well-known Langmuir model. Moreover, a revised cleaning protocol with NaCl instead of NaOH and minimizing the storage time has been identified as most critical for quantitatively reproducing the measured breakthrough curves. The internal geometry of both capsules is visualized by magnetic resonance imaging (MRI). The flow in the external hold-up volumes of the XT140 capsule was found to be more homogeneous as in the previously studied XT5 capsule. An attempt for model-based scale-up was apparently impeded by irregular pleat structures in the used XT140 capsule, which might lead to local variations in the linear velocity through the membrane stack. However, the presented approach is universal and can be applied to different capsules. The ZRM is shown to potentially help save valuable material and time, as the experiments required for model calibration are much cheaper than the predicted large-scale experiment at binding conditions. Biotechnol. Bioeng. 2013; 110: 1129–1141. © 2012 Wiley Periodicals, Inc.

Ghosh, Pranay; Vahedipour, Kaveh; Lin, Min; Vogel, Jens H; Haynes, Charles A; von Lieres, Eric

2013-01-01

3

Stability of radial swirl flows  

NASA Astrophysics Data System (ADS)

The energy gradient theory is used to examine the stability of radial swirl flows. It is found that the flow of free vortex is always stable, while the introduction of a radial flow will induce the flow to be unstable. It is also shown that the pure radial flow is stable. Thus, there is a flow angle between the pure circumferential flow and the pure radial flow at which the flow is most unstable. It is demonstrated that the magnitude of this flow angle is related to the Re number based on the radial flow rate, and it is near the pure circumferential flow. The result obtained in this study is useful for the design of vaneless diffusers of centrifugal compressors and pumps as well as other industrial devices.

Dou, H. S.; Khoo, B. C.

2012-11-01

4

Radial flow heat exchanger  

DOEpatents

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

Valenzuela, Javier (Hanover, NH)

2001-01-01

5

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

2012-11-30

6

Radial vorticity constraint in core flow modeling  

NASA Astrophysics Data System (ADS)

We present a new method for estimating core surface flows by relaxing the tangentially geostrophic (TG) constraint. Ageostrophic flows are allowed if they are consistent with the radial component of the vorticity equation under assumptions of the magnetostrophic force balance and an insulating mantle. We thus derive a tangentially magnetostrophic (TM) constraint for flows in the spherical harmonic domain and implement it in a least squares inversion of GRIMM-2, a recently proposed core field model, for temporally continuous core flow models (2000.0-2010.0). Comparing the flows calculated using the TG and TM constraints, we show that the number of degrees of freedom for the poloidal flows is notably increased by admitting ageostrophic flows compatible with the TM constraint. We find a significantly improved fit to the GRIMM-2 secular variation (SV) by including zonal poloidal flow in TM flow models. Correlations between the predicted and observed length-of-day variations are equally good under the TG and TM constraints. In addition, we estimate flow models by imposing the TM constraint together with other dynamical constraints: either purely toroidal (PT) flow or helical flow constraint. For the PT case we cannot find any flow which explains the observed SV, while for the helical case the SV can be fitted. The poor compatibility between the TM and PT constraints seems to arise from the absence of zonal poloidal flows. The PT flow assumption is likely to be negated when the radial magnetostrophic vorticity balance is taken into account, even if otherwise consistent with magnetic observations.

Asari, S.; Lesur, V.

2011-11-01

7

Electrokinetic chromatography without electroosmotic flow.  

PubMed

This review summarizes the various aspects of conducting electrokinetic chromatography in coated columns with suppressed electroosmotic flow. The specific features of the technique will be presented and the potential applications explored. The equations of migration, resolution and zone spreading for neutral solutes will be presented, compared, and contrasted with those of conventional electrokinetic chromatography in bare-silica columns. The principle of separation is the same in electrokinetic chromatography with or without electroosmotic flow; however, there are many significant differences that will be highlighted. PMID:9463907

Janini, G M; Issaq, H J; Muschik, G M

1997-12-19

8

Contained air flow in a radial tire  

SciTech Connect

Internal heat transfer through the tire cavity from the tire to the rim is strongly influenced by the speed distribution of the cavity air. For lack of any experimental data, exploratory tests with a hot-wire anemometer were performed on a radial tire operated at various loads, speeds, and inflation pressures. The measurement technique is described, and some results are presented. Cavity air flow is governed by the peristaltic action of the footprint region; however, it is strongly modified by secondary flows. The general speed distribution is very stable, with a peak at the leading edge of the footprint and a near-zero minimum at the tire top. Peak speeds of about 30% of the tire road speed were measured. These high speeds together with the augmenting effects of secondary flows may produce internal heat transfer coefficients well comparable with those at the outer surface.

Schuring, D.J.; Skinner, G.T.; Rae, W.J.

1981-01-01

9

Efficiency gain limits of the parallel segmented inlet and outlet flow concept in analytical liquid chromatography columns suffering from radial transcolumn packing density gradients.  

PubMed

The maximal gain in efficiency that can be expected from the use of the segmented column end fittings that were recently introduced to alleviate the effect of transcolumn packing density gradients has been quantified and generalized using numerical computations of the band broadening process. It was found that, for an unretained compound in a column with a parabolic packing density gradient, the use of a segmented inlet or a segmented outlet allows to eliminate about 60-100% of the plate height contribution (H(tc)) originating from a parabolic transcolumn velocity gradient in a d(c)=4.6 mm column. In a d(c)=2.1 mm column, these percentages change from 10 to 100%. Using a combined segmented in- and outlet, H(tc) can be reduced by about 90-100% (d(c)=4.6 mm column) or 20-100% (d(c)=2.1 mm column). The strong variation of these gain percentages is due to fact that they depend very strongly on the column length and the flow rate. Dimensionless graphs have been established that allow to directly quantify the effect for each specific case. It was also found that, in agreement with one's physical intuition, trans-column velocity profiles that are more flat in the central region benefit more from the concept than sharp, parabolic-like profiles. The gain margins furthermore tend to become smaller with increasing retention and increasing diffusion coefficient. PMID:22939209

Broeckhoven, Ken; Desmet, Gert

2012-08-17

10

Power Flow Analysis for Balanced and Unbalanced Radial Distribution Systems  

Microsoft Academic Search

This paper reports on an efficient method of power flow analysis for solving balanced and unbalanced radial distribution systems. The radial distribution system is modelled as a series of interconnected single feeders. Using Kirchoff's laws, a set of iterative power flow equations was developed to conduct the power flow studies. Due to the voltage dependency of loads in distribution systems,

H. M. Mok; S. Elangovan; M. M. A. Salama; Cao Longjian

11

New findings on radial distribution system load flow algorithms  

Microsoft Academic Search

In this paper, an attempt has been made to comprehensively compare the two most commonly used distribution load flow (DISTFLOW) models for radial networks to decide the better of the two for practical application. The paper also presents another novel method for radial distribution load flow and demonstrates its superiority over the two said models. Results have been obtained by

J. Nanda; M. S. Srinivas; S. S. Dey; L. L. Lai

2000-01-01

12

Fast decoupled power flow for unbalanced radial distribution systems  

Microsoft Academic Search

This paper presents a novel power flow formulation and an effective solution method for general unbalanced radial distribution systems. Comprehensive models are considered including lines, switches, transformers, shunt capacitors, cogenerators, and several types of loads. A new problem formulation of three-phase distribution power flow equations taking into account the radial structure of the distribution network is presented. A distinguishing feature

Ray D. Zimmerman; Hsiao-Dong Chiang

1995-01-01

13

SIMULATION OF FLOW IN A RADIAL FLOW FIXED BED REACTOR (RFBR)  

Microsoft Academic Search

The flow in a radial flow fixed bed reactor (RFBR) was simulated using computational fluid dynamics (CFD). There are four types of RFBR based on the axial direction of the flow in the distributing channel and the center pipe and the reactor radial flow direction. These types are known as CP-z, CP-?, CF-z and CF-? configurations. Flow in all four

Aqeel A. KAREERI; Habib H. ZUGHBI; Habib H. AL-ALI

14

Zonal flows in stellarators in an ambient radial electric field  

SciTech Connect

The linear dynamics of zonal flows is addressed in stellarator geometry in the presence of an ambient (neoclassical) radial electric field. Global gyrokinetic particle-in-cell simulations are used to study the properties of the residual flow and its dependence on the plasma parameters and magnetic geometry. Properties of the zonal flow are compared in different magnetic geometries.

Mishchenko, Alexey; Kleiber, Ralf [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, D-17491 Greifswald (Germany)

2012-07-15

15

Generation 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), is increasingly used to interpret hydraulic tests to account for non-radial flow. Flow dimension can be estimated directly from the second derivative of pumping test drawdown versus log time and can be described as the change in cross-sectional area of flow with respect to radial distance from the borehole. Previously, it was not clear if flow dimension was an intrinsic property of a medium or an artifact of the analysis technique. Representing non-radial flow in a 2D numerical model has been problematic. As part of an effort to understand how to structure heterogeneous transmissivity to create the type of non-radial flow signatures commonly observed, we generated spatially correlated binary random transmissivity fields with directional anisotropy in the correlation length. Analysis of simulated pumping tests in these fields provided the same types of non-radial diagnostic responses commonly observed in pumping tests in a fractured dolomite at the Waste Isolation Pilot Plant (WIPP) site. Our method may provide insight into how to better conceptualize flow systems and, with further analysis and understanding, allow us to condition future transmissivity fields. 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.

2006-12-01

16

Radial Chromatography for the Separation of Nitroaniline Isomers  

ERIC Educational Resources Information Center

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

Miller, Robert B.; Case, William S.

2011-01-01

17

Radial Chromatography for the Separation of Nitroaniline Isomers  

ERIC Educational Resources Information Center

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

Miller, Robert B.; Case, William S.

2011-01-01

18

Boiling radial flow in fractures of varying wall porosity  

Microsoft Academic Search

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.

Robb Allan Barnitt; Robb Allan

2000-01-01

19

A simple algorithm for unbalanced radial distribution system load flow  

Microsoft Academic Search

Many programs of real-time applications in the area of distribution automation, such as network optimization, Var planning, switching, state estimation, and so forth, require a robust and efficient load flow method for distribution systems. Such a load flow method must be able to model the special features of distribution systems in sufficient detail. Many approaches for unbalanced radial distribution system

Sivkumar Mishra

2008-01-01

20

Longitudinal Dispersivity in a Radial Diverging Flow Field  

NASA Astrophysics Data System (ADS)

Hydrodynamic dispersion is an important factor controlling contaminant migration in the subsurface environment. However, few comprehensive data sets exist for evaluating the impact of travel distance and site heterogeneity on solute dispersion under non-uniform flow conditions. In addition, anionic tracers are often used to estimate physical transport parameters based on an erroneous assumption of conservative (i.e., non-reactive) behavior. Therefore, a series of field experiments using tritiated water and several other commonly used hydrologic tracers (Br, Cl, FBAs) were conducted in the water-table aquifer on the U.S. Department of Energy's Savannah River Site (Aiken, SC) to evaluate solute transport processes in a diverging radial flow field. For each experiment, tracer-free groundwater was injected for approximately 24 hours at a fixed rate of 56.7 L/min (15 gpm) to establish a forced radial gradient prior to the introduction of a tracer pulse. After the tracer pulse, the forced gradient was maintained throughout the experiment using non-labeled groundwater. Tracer migration was monitored using a set of six sampling wells radially spaced at approximate distances of 1.5, 3, and 4.5 meters from a central injection well. Each sampling well was further divided into three discrete sampling depths that were monitored continuously throughout the course of the tracer experiment. At various time intervals, discrete groundwater samples were collected from all 18 sampling ports for tritium analysis. Longitudinal dispersivity for tritium breakthrough at each sampling location was estimated using analytical approximations of the convection dispersion equation (CDE) for radial flow assuming an instantaneous Dirac pulse and a pulse of known duration. The results were also compared to dispersivity values derived from fitting the tracer data to analytical solutions derived from assuming uniform flow conditions. Tremendous variation in dispersivity values and tracer arrival times were observed between wells located at similar radial distances and between sampling zones within a given well, with multiple arrival peaks observed for some monitoring locations. However, lower dispersivity values were observed for all data sets when fitting the breakthrough data using the radial flow approximations when compared to uniform flow case. In addition, the 95% confidence interval span for the dispersivity estimate was always smaller for the radial flow solution, indicating a better model fit when compared to the uniform flow model. Additional logistical obstacles in conducting such an extensive set of field tracer experiments will also be discussed.

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

2005-12-01

21

A New Power Flow Method in Radial Distribution Systems  

Microsoft Academic Search

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

Wataru Ohyoshi; Hiroyuki Mori

2006-01-01

22

Nozzle Guide Vane Flow in Radial Inflow Turbines.  

National Technical Information Service (NTIS)

Radial inflow turbines have various applications in industry and are being used as major components of gas turbines and turbochargers. The details of the flow phenomena within these machines are ill-define especially in small high speed units where small ...

S. H. Zaidi R. L. Elder

1994-01-01

23

Improved algorithm for radial distribution networks load flow solution  

Microsoft Academic Search

The main aim of this paper is to present an improved method to solve load flow problem in balanced radial distribution systems with laterals. The method is efficient and easy to implement. Based on electric circuit laws, this method is iterative and allows the evaluation of both, voltage (rms) values and phase-angles. The phase-angles although of small values become necessary

Abdellatif Hamouda; Khaled Zehar

2011-01-01

24

A robust power flow algorithm for radial distribution systems  

Microsoft Academic Search

In this paper, a new algorithm is presented to solve the power flow problem in radial distribution systems. The proposed method takes into account the voltage dependency of static loads, and line charging capacitance. The method is based on the forward and backward voltage calculation by using polynomial voltage equation and KirchofPs Law for each branch. Convergence speed and reliability

U. Eminoglu; M. H. Hocaoglu

2005-01-01

25

LOAD FLOW SOLUTION OF UNBALANCED RADIAL DISTRIBUTION SYSTEMS  

Microsoft Academic Search

This paper presents a simple three phase load flow method to solve three-phase unbalanced radial distribution system (RDS). It solves a simple algebraic recursive expression of voltage magnitude, and all the data are stored in vector form. The algorithm uses basic principles of circuit theory and can be easily understood. Mutual coupling between the phases has been included in the

J. B. V. SUBRAHMANYAM

2009-01-01

26

A novel power flow solution methodology for radial distribution systems  

Microsoft Academic Search

This paper presents a novel and efficient procedure for accomplishing the load flow calculations in an electrical radial distribution system. The proposed approach utilizes the forward sweep algorithm for the iterative evaluation of node parameters which is based on the Kirchhoff's current law [KCL] and Kirchhoff's voltage law [KVL]. The methodology has been made suitable for larger distribution systems by

P. Ravi Babu; M. P. V. V. R. Kumar; V. S. Hemachandra; M. P. R. Vanamali

2010-01-01

27

Temporal Moments for Kinetically Sorbing Solute Transport in Radial Flow  

Microsoft Academic Search

We will apply a method of determining the temporal moments of kinetically sorbing solute transport to radial flow situations. The temporal moments for kinetically sorbing solute are determined from the travel time cumulative distribution function (CDF) of a non-reactive solute and the geochemical model describing the sorption and desorption of the reactive solute. The method is a stochastic approach based

A. E. Lawrence; X. Sánchez-Vila; Y. Rubin

2001-01-01

28

Flow-gated radial phase-contrast imaging in the presence of weak flow.  

PubMed

To implement a flow-gating method to acquire phase-contrast (PC) images of carotid arteries without use of an electrocardiography (ECG) signal to synchronize the acquisition of imaging data with pulsatile arterial flow. The flow-gating method was realized through radial scanning and sophisticated post-processing methods including downsampling, complex difference, and correlation analysis to improve the evaluation of flow-gating times in radial phase-contrast scans. Quantitatively comparable results (R = 0.92-0.96, n = 9) of flow-related parameters, including mean velocity, mean flow rate, and flow volume, with conventional ECG-gated imaging demonstrated that the proposed method is highly feasible. The radial flow-gating PC imaging method is applicable in carotid arteries. The proposed flow-gating method can potentially avoid the setting up of ECG-related equipment for brain imaging. This technique has potential use in patients with arrhythmia or weak ECG signals. PMID:22552864

Peng, Hsu-Hsia; Huang, Teng-Yi; Wang, Fu-Nien; Chung, Hsiao-Wen

2012-05-03

29

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

2012-04-10

30

Multiphase flow modeling in centrifugal partition chromatography  

Microsoft Academic Search

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

S. Adelmann; C. Schwienheer; G. Schembecker

2011-01-01

31

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

Microsoft Academic Search

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

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

2008-01-01

32

A Visual Study of Radial Inward Choked Flow of Liquid Nitrogen.  

National Technical Information Service (NTIS)

A visual study of the radial inward choked flow of liquid nitrogen was conducted. Data and high speed moving pictures were obtained. The study indicated the following: (1) steady radial inward choked flow seems equivalent to steady choked flow through axi...

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

1973-01-01

33

Skin effect in generalized radial flow model in fractured media  

NASA Astrophysics Data System (ADS)

A generalized radial flow model, treating the flow dimension as an arbitrary number and taking into account the well skin effect, is presented to describe the transient head distribution in a fractured medium under the Robin condition during constant-head tests. The Laplace-domain solution for the head distribution is first developed via the Laplace transforms; and the corresponding time-domain solution in terms of the hydraulic head is then obtained using the Bromwich integral method. In addition, based on the head solution and Darcy's law, the solution for the wellbore flux is further developed to investigate the skin effect. It is found that the skin effect on the wellbore flux is significant at early times. Under this circumstance, it would not be appropriate to neglect the skin effect in the model in determining the hydraulic parameters from the analysis of field data. Our solutions will be useful for the predictions of the spatial and temporal head distribution and wellbore flux or in investigating the skin effect on the head distribution and wellbore flux for flow with various dimensions in fractured media.

Chang, Ya-Chi; Yeh, Hund-Der

2011-04-01

34

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

35

Characterizing gaseous flow in submicron chromatography columns.  

SciTech Connect

Enormous interest exists to develop the next generation of an integrated microsystem for chemical and biological analysis ({mu}ChemLab{trademark}) and to further reduce the volume of the system. One approach is to scale down the size of critical components and to explore any pumping mechanism that can minimize the power requirement. Since the majority of the pumping requirement is to overcome the wall resistance in the gas chromatography (GC) column, our attention is to study the gas flow in this GC column. As the column dimension decreases, the gaseous flow will go from a continuum regime into a non-continuum regime; i.e., slip, transition, and free molecular regimes. Thus it is very important to well characterize the gaseous flow in submicron columns and to understand its flow behavior. Specifically, in this study, our focus is to investigate the effects of viscosity, rarefaction, and compressibility as the column dimension decreases. Both theoretical predictions and experimental results will be presented.

Wong, Chung-Nin Channy

2003-05-01

36

A robust three phase power flow algorithm for radial distribution systems  

Microsoft Academic Search

An efficient load flow solution technique is required as a part of the distribution automation (DA) system for taking various control and operations decisions. This paper presents an efficient and robust three phase power flow algorithm for application to radial distribution networks. This method exploits the radial nature of the network and uses forward and backward propagation to calculate branch

D. Thukaram; H. M. Wijekoon Banda; Jovitha Jerome

1999-01-01

37

A Novel Load Flow Method for Radial Distribution Systems for Realistic Loads  

Microsoft Academic Search

The need for fast load flow algorithms for radial distribution networks that take advantage of their particular structure has been increasing for planning and optimization. In this article, a novel load flow method of radial distribution systems is presented. In the proposed method, different realistic loads have been considered, as loads are voltage dependent in distribution systems. The effect of

K. Nagaraju; S. Sivanagaraju; T. Ramana; P. V. Prasad

2011-01-01

38

An investigation of radial tracer flow in naturally fractured reservoirs  

SciTech Connect

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

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

1991-01-01

39

lr2dinv: A finite-difference model for inverse analysis of two-dimensional linear or radial groundwater flow  

Microsoft Academic Search

We have developed a program for inverse analysis of two-dimensional linear or radial groundwater flow problems. The program, lr2dinv, 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

Geoffrey C. Bohling; James J. Butler

2001-01-01

40

A New Approach to Load Flow Solutions for Radial Distribution System  

Microsoft Academic Search

This paper presents a new approach to load flow solutions for radial distribution system, in which the choice of the switches to be opened is based on the calculation of voltage at the buses, real and reactive power flowing through lines, real power losses and voltage deviation, using distribution load flow (DLF) program. In the process of load flow calculation,

T. Thakur; J. Dhiman

2006-01-01

41

Radial flow has little effect on clusterization at intermediate energies in the framework of the lattice gas model  

SciTech Connect

The lattice gas model was extended to incorporate the effect of radial flow. Contrary to popular belief, radial flow has little effect on the clusterization process in intermediate energy heavy-ion collisions except adding an ordered motion to the particles in the fragmentation source. We compared the results from the lattice gas model with and without radial flow to experimental data. We found that charge yields from central collisions are not significantly affected by inclusion of any reasonable radial flow.

Das, C.B. [Physics Department, McGill University, Montreal, H3A 2T8 (Canada); Physics Division, Variable Energy Cyclotron Center, 1/AF Bidhannagar, Kolkata 700 064 (India); Shi, L.; Gupta, S. Das [Physics Department, McGill University, Montreal, H3A 2T8 (Canada)

2004-12-01

42

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

43

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

44

The benefits of looping a radial distribution system with a power flow controller  

Microsoft Academic Search

In this paper the benefits of looping the conventional radial distribution system by a series power electronic system to control power flow has been investigated. The conventional radial electrical distribution system will change to loop or even meshed system due to the deregulation of electrical system and connection of Distributed Generation to Medium and Low voltage in future. However looping

M. Saradarzadeh; S. Farhangi; J. L. Schanen; P.-O. Jeannin; D. Frey

2010-01-01

45

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

46

Some aspects of the performance of refrigerating thermojunctions with radial flow of current  

Microsoft Academic Search

An expression for the maximum temperature difference DeltaTmax produced between the hot and cold junctions of a thermocouple is derived when the arms are disks of thermoelectric material. In these disks the flow of current is in a direction radially inwards or radially outwards. No assumptions have been made about the distribution of the Joule heat over the hot and

K. Landecker

1976-01-01

47

Effects of the radial flows on the chemical evolution of the Milky Way disk  

NASA Astrophysics Data System (ADS)

Context. The majority of chemical evolution models assume that the Galactic disk forms by means of infall of gas and divide the disk into several independent rings without exchange of matter between them. However, if gas infall is important, radial gas flows should be taken into account as a dynamical consequence of infall. Aims: We test the effects of radial gas flows on detailed chemical evolution models (one-infall and two-infall) of the Milky Way disk with different prescriptions for the infall law and star formation rate. Methods: We modified the equation of chemical evolution to include radial gas flows according to the method described in Portinari & Chiosi (2000, A&A, 355, 929). Results: We found that with a gas radial inflow of constant speed the metallicity gradient tends to steepen. Taking into account a constant timescale for the infall rate along the Galaxy disk and radial flows with a constant speed, we obtained too flat a gradient, at variance with data, implying that an inside-out formation and/or a variable gas flow speed are required. To explain the observed gradients, the gas flow should increase in modulus with the galactocentric distance, in both the one-infall and two-infall models. However, the inside-out disk formation coupled with a threshold in the gas density (only in the two-infall model) for star formation and/or a variable efficiency of star formation with galactocentric distance can also reproduce the observed gradients without radial flows. Conclusions: We show that the radial flows can be the most important process in reproducing abundance gradients but only with a variable gas speed. Finally, one should consider that uncertainties in the data concerning gradients prevent us from drawing firm conclusions. Future more detailed data will help us to ascertain whether the radial flows are a necessary ingredient in the formation and evolution of the Galactic disk and disks in general.

Spitoni, E.; Matteucci, F.

2011-07-01

48

Numerical model of fluid flow and oxygen transport in a radial-flow microchannel containing hepatocytes.  

PubMed

The incorporation of monolayers of cultured hepatocytes into an extracorporeal perfusion system has become a promising approach for the development of a temporary bioartificial liver (BAL) support system. In this paper we present a numerical investigation of the oxygen tension, shear stress, and pressure drop in a bioreactor for a BAL composed of plasma-perfused chambers containing monolayers of porcine hepatocytes. The chambers consist of microfabricated parallel disks with center-to-edge radial flow. The oxygen uptake rate (OUR), measured in vitro for porcine hepatocytes, was curve-fitted using Michaelis-Menten kinetics for simulation of the oxygen concentration profile. The effect of different parameters that may influence the oxygen transport inside the chambers, such as the plasma flow rate, the chamber height, the initial oxygen tension in the perfused plasma, the OUR, and K(m) was investigated. We found that both the plasma flow rate and the initial oxygen tension may have an important effect upon oxygen transport. Increasing the flow rate and/or the inlet oxygen tension resulted in improved oxygen transport to cells in the radial-flow microchannels, and allowed significantly greater diameter reactor without oxygen limitation to the hepatocytes. In the range investigated in this paper (10 microns < H < 100 microns), and for a constant plasma flow rate, the chamber height, H, had a negligible effect on the oxygen transport to hepatocytes. On the contrary, it strongly affected the mechanical stress on the cells that is also crucial for the successful design of the BAL reactors. A twofold decrease in chamber height from 50 to 25 microns produced approximately a fivefold increase in maximal shear stress at the inlet of the reactor from 2 to 10 dyn/cm2. Further decrease in chamber height resulted in shear stress values that are physiologically unrealistic. Therefore, the channel height needs to be carefully chosen in a BAL design to avoid deleterious hydrodynamic effects on hepatocytes. PMID:10080090

Ledezma, G A; Folch, A; Bhatia, S N; Balis, U J; Yarmush, M L; Toner, M

1999-02-01

49

Scaleup of monoclonal antibody purification using radial streaming ion exchange chromatography.  

PubMed

A scaleup study of the radial streaming chromatography (ZetaPrep technique) using hybridoma culture supernatant as model protein solution is described in this article. Lab and pilot cartridges were tested. Scaleup factors were calculated from the lab experiments and compared to the data obtained at pilot level. The procedure consists of three different steps: microfiltration, diafiltration, and the ZetaPrep technique using QAE cartridges. Diafiltration was used to condition the clarified culture supernatant. Calculating the elution volumes for the pilot level (ZetaPrep 800) from the smallest lab cartridge (ZetaPrep 15), a difference between calculated and experimental values of 230% was obtained. The difference between calculated and experimental values using results from ZetaPrep 100, a preparative cartridge, was 120%. At pilot level it is possible to purify 10 L culture supernatant within 3 h including regeneration and reequilibration of the cartridge. This procedure is useful for monoclonal antibodies (mAb) with a low isoelectric point (pl). The pl's of the mAb which was used in this work are in the range 5.4-6.1. PMID:18584753

Jungbauer, A; Unterluggauer, F; Uhl, K; Buchacher, A; Steindl, F; Pettauer, D; Wenisch, E

1988-07-20

50

Measurement of Velocity Profile and Decay of Velocity from a Radial Flow Jet.  

National Technical Information Service (NTIS)

The radial jet was developed by a flow of air exiting through a nozzle designed to turn the flow 90 degrees and establish a uniform profile. The flow field was measured with total pressure rakes. A hot-wire anemometer was used for certain profiles and cen...

M. D. Howe

1968-01-01

51

Application of continuation power flow method in radial distribution systems  

Microsoft Academic Search

The paper presents a set of equations (SOE) comprising voltage magnitude and nodal real\\/reactive power balance equations to model a radial distribution system (RDS). The voltage equations in the SOE have dual roots. Then a Newton–Raphson (NR) method is presented to solve the SOE to determine the voltage solution of an RDS. This NR method is extended using the continuation

A. Dukpa; B. Venkatesh; M. El-Hawary

2009-01-01

52

Coupled azimuthal and radial flows and oscillations in a rotating plasma  

SciTech Connect

Nonlinear coupling between the radial, axial, and azimuthal flows in a cold rotating plasma is considered nonperturbatively by first constructing a basis solution for a rotating flow. Simple but exact solutions that describe an expanding plasma with oscillatory flow fields are then obtained. These solutions show that the energy in the radial and axial flow components can be transferred to the azimuthal component but not the vice versa. Nonlinear electron velocity oscillations in the absence of electron density oscillations at the same frequency are shown to exist.

Karimov, A. R. [Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13/19, Moscow 127412 (Russian Federation); Stenflo, L. [Department of Plasma Physics, Umeaa University, SE-90187 Umeaa (Sweden) and Department of Physics, Linkoeping University, SE-58183 Linkoeping (Sweden); Yu, M. Y. [Department of Physics, Institute for Fusion Theory and Simulation, Zhejiang University, 310027 Hangzhou (China) and Institut fuer Theoretische Physik I, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2009-06-15

53

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

54

An effective topological and primitive impedance based three phase load flow method for radial distribution systems  

Microsoft Academic Search

In this paper, an effective topological primitive impedance based three-phase distribution power flow algorithm is developed. This method fully exploits the radial structure of the network and solves the distribution load flow directly. An effective data structure is proposed to identify all those lines that are incident to the path between the feeding bus and any selected bus. Using this

K. Prakash; M. Sydulu

2008-01-01

55

A novel and fast three-phase load flow for unbalanced radial distribution systems  

Microsoft Academic Search

A novel and fast three-phase load flow algorithm for unbalanced radial distribution systems is proposed in this paper. The proposed method uses branch voltages as state variables and employs the Newton-Raphson (NR) algorithm to solve the load flow problem. By utilizing branch voltages as state variables, a constant Jacobian matrix can be obtained, and a building algorithm for Jacobian matrix

Jen-Hao Teng; Chuo-Yean Chang

2002-01-01

56

Flow driven by a shrouded spinning disk with axial suction and radial inflow  

Microsoft Academic Search

The viscous flow confined in a finite cylinder when one endwall disk and the sidewall are spinning about the central axis is studied. We examine the internal flow when a uniform axial suction through the spinning disk and a concomitant uniform radial inflow through the spinning sidewall are imposed. The rotational Reynolds number is large and the cylinder aspect ratio

Hyun Jae Min; Kim Jae Won

1987-01-01

57

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

Microsoft Academic Search

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

A. W. Reichert; H. Simon

1997-01-01

58

A Integrated Power Flow Algorithm for Radial Distribution System with DGs Based on Voltage Regulating  

Microsoft Academic Search

It proposes a promising power flow analysis method for radial distribution system with distributed generations (DGs), combined with reactive power compensation facilities. In the power flow analysis, suitable models are determined for different DG units, Q-sources including Static Var Compensator, Switched Capacitor or Shunt Capacitor and Step Voltage Regulator. A helpful method is presented to deal with the PV node,

Liu Qingzhen; Cai Jinding

2010-01-01

59

New Load Flow Method SE Oriented For Large Radial Distribution Networks  

Microsoft Academic Search

There is a growing interest in the electric utilities to raise their efficiency in the operation and design of transmission and distribution of systems. This work proposes a new, fast, robust and efficient method for the load flow solution, in balanced and unbalanced radial distribution systems. It is about a sequential method, based on the S-E load flow algorithm devised

H. M. Khodr; L. Ocque; J. M. Yusta; M. A. Rosa

2006-01-01

60

An Efficient Load Flow Solution for Radial Distribution Network Including Voltage Dependent Load Models  

Microsoft Academic Search

An efficient load flow solution is required for automated distribution network for operation and control, and for planning and optimization. This article presents a novel load flow algorithm for solving radial distribution systems. It solves simple algebraic recursive equation of receiving end voltage. In this algorithm, different static load models have been included as the loads are voltage dependent in

S. Satyanarayana; T. Ramana; S. Sivanagaraju; G. K. Rao

2007-01-01

61

Electrocatalytic hydrogenation of soybean oil in a radial flow-through Raney nickel powder reactor  

Microsoft Academic Search

Soybean oil has been hydrogenated electrocatalytically on Raney nickel powder catalyst at atmospheric pressure and moderate temperatures in a novel undivided packed bed radial flow-through reactor. The reactor consisted of a single anode\\/cathode tubular element, where Raney nickel catalyst powder was contained in the annular space between two concentric porous ceramic tubes and the flow of the reaction medium (a

G. Yusem; P. N. Pintauro; P.-C. Cheng; W. An

1996-01-01

62

Effects of gaze on vection from jittering, oscillating, and purely radial optic flow.  

PubMed

In this study, we examined the effects of different gaze types (stationary fixation, directed looking, or gaze shifting) and gaze eccentricities (central or peripheral) on the vection induced by jittering, oscillating, and purely radial optic flow. Contrary to proposals of eccentricity independence for vection (e.g., Post, 1988), we found that peripheral directed looking improved vection and peripheral stationary fixation impaired vection induced by purely radial flow (relative to central gaze). Adding simulated horizontal or vertical viewpoint oscillation to radial flow always improved vection, irrespective of whether instructions were to fixate, or look at, the center or periphery of the self-motion display. However, adding simulated high-frequency horizontal or vertical viewpoint jitter was found to increase vection only when central gaze was maintained. In a second experiment, we showed that alternating gaze between the center and periphery of the display also improved vection (relative to stable central gaze), with greater benefits observed for purely radial flow than for horizontally or vertically oscillating radial flow. These results suggest that retinal slip plays an important role in determining the time course and strength of vection. We conclude that how and where one looks in a self-motion display can significantly alter vection by changing the degree of retinal slip. PMID:19933567

Palmisano, Stephen; Kim, Juno

2009-11-01

63

Radial variation in sap flow in five laurel forest tree species in Tenerife, Canary Islands.  

PubMed

Variations in radial patterns of xylem water content and sap flow rate were measured in five laurel forest tree species (Laurus azorica (Seub.) Franco, Persea indica (L.) Spreng., Myrica faya Ait., Erica arborea L. and Ilex perado Ait. ssp. platyphylla (Webb & Berth.) Tutin) growing in an experimental plot at Agua García, Tenerife, Canary Islands. Measurements were performed around midday during warm and sunny days by the heat field deformation method. In all species, water content was almost constant (around 35% by volume) over the whole xylem cross-sectional area. There were no differences in wood color over the whole cross-sectional area of the stem in most species with the exception of E. arborea, whose wood became darker in the inner layers. Radial patterns of sap flow were highly variable and did not show clear relationships with tree diameter or species. Sap flow occurred over the whole xylem cross-sectional area in some species, whereas it was limited to the outer xylem layers in others. Sap flow rate was either similar along the xylem radius or exhibited a peak in the outer part of the xylem area. Low sap flow rates with little variation in radial pattern were typical for shaded suppressed trees, whereas dominant trees exhibited high sap flow rates with a peak in the radial pattern. Stem damage resulted in a significant decrease in sap flow rate in the outer xylem layers. The outer xylem is more important for whole tree water supply than the inner xylem because of its larger size. We conclude that measurement of radial flow pattern provides a reliable method of integrating sap flow from individual measuring points to the whole tree. PMID:12651490

Jiménez, M. Soledad; Nadezhdina, Nadezhda; Cermák, Jan; Morales, Domingo

2000-11-01

64

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

65

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

66

A dynamic membrane reactor concept for naphtha reforming, considering radial-flow patterns for both sweeping gas and reacting materials  

Microsoft Academic Search

Hydrogen will become an essential energy source in the near future. In this regard, refineries can be considered as alternative sources of hydrogen production. In the present study, a tubular membrane reactor with radial-flow patterns of the sweeping gas and the naphtha feed named RF-TMR is proposed as a novel configuration for radial-flow naphtha reformers. Radial-flow reactors are used in

D. Iranshahi; E. Pourazadi; K. Paymooni; M. R. Rahimpour; A. Jahanmiri; B. Moghtaderi

67

Three Phase Probabilistic Load Flow in Radial Distribution Networks  

SciTech Connect

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

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

2012-01-01

68

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

SciTech Connect

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

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

2002-11-01

69

A modified power flow calculation method for radial distribution system  

Microsoft Academic Search

Distribution power flow calculation is base of distribution system analysis. The characteristics and differences of Back\\/forward sweep method and Newton method are compared and analyzed, and a modified back\\/forward sweep method is proposed based on the conventional back\\/forward sweep method, in which the correction equation of node voltage in the back sweep process is just simply replaced by a new

Liu Wei; Ning Wen-hui; Huang Dong-shan

2008-01-01

70

LONGITUDINAL DISPERSION AND TRACER MIGRATION IN A RADIAL FLOW FIELD  

Microsoft Academic Search

Hydrodynamic dispersion is an important factor controlling contaminant migration in the subsurface environment. However, few comprehensive data sets ex- ist for evaluating the impact of travel distance and site heterogeneity on solute dispersion under non-uniform flow conditions. In addition, anionic tracers are often used to estimate physical transport parameters based on an erroneous assumption of conservative (i.e., non-reactive) behavior. Therefore,

John C. Seaman

71

Longitudinal Dispersivity in a Radial Diverging Flow Field  

Microsoft Academic Search

Hydrodynamic dispersion is an important factor controlling contaminant migration in the subsurface environment. However, few comprehensive data sets exist for evaluating the impact of travel distance and site heterogeneity on solute dispersion under non-uniform flow conditions. In addition, anionic tracers are often used to estimate physical transport parameters based on an erroneous assumption of conservative (i.e., non-reactive) behavior. Therefore, a

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

2005-01-01

72

Radial Flow of Pressured Hot Water Through Narrow Cracks  

SciTech Connect

Geothermal wells discharging hundreds of tons/hour of steam-water mixtures may be supplied at depth from one very narrow crack of width 1 to 2 mm, or alternatively, from some hundreds of hairline cracks. In the former case, turbulent flow takes place out to tens of meters from the well while the sum of frictional and kinetic pressure-drop indicates the flashing distance to be of the order of 10 cm from the well wall for pressure-temperature equilibrium. However it is unlikely that equilibrium obtains because of the high water velocity (order of 100 m/s) near the well giving no time for bubble nucleation. Flashing and hence mineral deposition are therefore not at all likely in the crack but can occur within the well from the crack horizon upwards. In the case of a multitude of fine cracks giving the same total flow, streamline conditions prevail over the flow path with the flash front a meter or so from the well, hence deposition is a possibility.

James, Russell

1983-12-15

73

Use of a mechanical leech in a reverse-flow radial forearm flap: case report.  

PubMed

The reverse-flow radial forearm flap provides excellent coverage for distal upper-limb defects. It is simply raised and does not require microsurgical skills. However, since its vascular pedicle is reversed, its venous outflow can be significantly diminished because of the venous valves. The authors present the case of a 16-year-old patient with a sagittal amputation of the radial aspect of the right thumb, who manifested at the time of surgery marked venous engorgement of a reverse-flow radial forearm flap. This was successfully relieved by the placement of a mechanical leech consisting of a Silastic rubber catheter--of the kind used to gain central vascular access in newborns--introduced in the lumen of the reversed vein at the extremity of the flap. This permitted intermittent evacuation of blood from the flap postoperatively, contributing to the success of this procedure. The technique used is detailed and pertinent literature is reviewed. PMID:11499467

La Scala, G C; Carroll, S M; Forrest, C R; Zuker, R M

2001-07-01

74

Micellar electrokinetic chromatography in zero-electroosmotic flow environment  

Microsoft Academic Search

Micellar electrokinetic chromatography (MEKC) is conducted in polyacrylamide-coated capillaries under almost complete suppression of electroosmotic flow. The equations of migration and resolution for neutral solutes in this mode of MEKC operation are presented. The technique is termed reversed-flow MEKC (RF-MEKC) because, in contrast to MEKC in bare-silica capillaries (N-MEKC), solute migration order is reversed and solute migration time is inversely

George M. Janini; Gary M. Muschik; Haleem J. Issaq

1996-01-01

75

An Improved Backward\\/Forward Sweep Load Flow Algorithm for Radial Distribution Systems  

Microsoft Academic Search

This letter presents an improved backward\\/ forward sweep algorithm for three-phase load-flow analysis of radial distribution systems. In the backward sweep, Kirchhoff's Current Law and Kirchhoff's Voltage Law are used to calculate the upstream bus voltage of each line or a transformer branch. Then, the linear proportional principle is adopted to find the ratios of the real and imaginary components

G. W. Chang; S. Y. Chu; H. L. Wang

2007-01-01

76

Fuzzy load flow in balanced and unbalanced radial distribution systems incorporating composite load model  

Microsoft Academic Search

This paper presents a fuzzy approach load flow for balanced and unbalanced radial distribution systems with incorporating load model. Fuzzy set theory proposes an appropriate way to model inexactly expressed information and data which have uncertainty. In this paper the combination of fuzzy models and techniques for electrical distribution systems is presented. The theories relating to the fuzzy numbers are

Belal Mohammadi Kalesar; Ali Reza Seifi

2010-01-01

77

PARAMETRIC STUDY AND DESIGN OPTIMIZATION OF A RADIAL FLOW PUMP IMPELLER  

Microsoft Academic Search

In the present work a parametric study of a radial flow pump impeller concerning the wrap angle of the blades is presented. The design scenario contemplated here involves the maximization of impeller's efficiency by adjusting the blade's wrap angle and the number of blades. The method is used to improve the performance of an impeller of known characteristics. An optimal

Vasilios A. Grapsas; John S. Anagnostopoulos; Dimitrios E. Papantonis

78

Numerical model of liquid flow in a rotating cylinder with radially arranged elastic ribs  

NASA Astrophysics Data System (ADS)

The boundary-value problem of the vortex flow of a viscous incompressible liquid in a rotating cavity having the shape of a circular cylinder in which elastic radial ribs (plates) are embedded as intense vortex sources is formulated and solved using numerical methods. The solution results are used to calculate the drag coefficient of the ribs.

Bogoryad, I. B.; Lavrova, N. P.

2013-03-01

79

A new power flow method for radial distribution systems including voltage dependent load models  

Microsoft Academic Search

This paper presents a simple and efficient method to solve the power flow problem in radial distribution systems. The proposed method takes into account voltage dependency of static loads, and line charging capacitance. The method is based on the forward and backward voltage updating by using polynomial voltage equation for each branch and backward ladder equation (Kirchoff's Laws). Convergence ability

Ulas Eminoglu; M. Hakan Hocaoglu

2005-01-01

80

A Simplified Approach for Load Flow Analysis of Radial Distribution Network  

Microsoft Academic Search

This paper presents a simple approach for load flow analysis of a radial distribution network. The proposed approach utilizes forward and backward sweep algorithm based on Kirchoff's current law (KCL) and Kirchoff's voltage law (KVL) for evaluating the node voltages iteratively. In this approach, computation of branch current depends only on the current injected at the neighbouring node and the

K. Vinoth Kumar; M. P. Selvan

2008-01-01

81

A simplified approach for load flow analysis of radial distribution network with embedded generation  

Microsoft Academic Search

This paper presents a simple approach for load flow analysis of a radial distribution network with embedded generation. The proposed approach utilizes forward and backward sweep algorithm based on Kirchoffpsilas current law (KCL) and Kirchoffpsilas voltage law (KVL) for evaluating the node voltages iteratively. In this approach, computation of branch current depends only on the current injected at the neighbouring

K Vinoth Kumar; M. P. Selvan

2008-01-01

82

Loop frame of reference based three-phase power flow for unbalanced radial distribution systems  

Microsoft Academic Search

This paper introduces a novel three-phase power flow approach for unbalanced radial distribution systems. The proposed approach is developed based on the loop frame of reference, rather than the traditional bus frame of reference. On the basis of the loop frame of reference, a simple direct iterative method in impedance form is applied. Basic graph theory and injection current technique

Tsai-Hsiang Chen; Nien-Che Yang

2010-01-01

83

Simple and efficient method for load flow solution of radial distribution networks  

Microsoft Academic Search

The paper presents a simple and efficient method for solving radial distribution networks. The proposed method involves only the evaluation of a simple algebraic expression of voltage magnitudes and no trigonometric functions as opposed to the standard load flow case. Thus, computationally the proposed method is very efficient and it requires less computer memory. The proposed method can easily handle

A. Kalam

1995-01-01

84

Radial particle flow, electrical conductivity and thermal energy content in the Frascati Tokamak Upgrade  

Microsoft Academic Search

Experimental determinations of the radial plasma flow velocity, of Zeff and of the thermal energy content, made on the Frascati Tokamak Upgrade (FTU), have been compared with the predictions of the conventional neoclassical theory, of the extended neoclassical theory and of the pseudoneoclassical theory. In the comparison only the momentum balance and continuity equations were used. The best overall agreement

G. Bracco; S. E. Segre; V. Zanza; G. Apruzzese; F. Bombarda; P. Buratti; F. Crisanti; R. de Angelis; D. Frigione; L. Gabellier; M. Grolli; H. Kroegler; G. Mazzitelli; D. H. McNeill; A. Moleti; S. Podda; M. Zerbini

1994-01-01

85

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

EPA Science Inventory

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

86

Lectin-glycoenzyme column chromatography monitored by enzyme flow microcalorimetry  

Microsoft Academic Search

A method based on the flow microcalorimetric determination of catalytic activity of immobilized enzyme in a so-called enzyme thermistor was used to monitor the process of lectin affinity chromatography of invertase on Concanavalin A-bead cellulose. The strong biospecific interaction between Concanavalin A and invertase was employed to determine the bound enzyme and this principle was used for the investigation of

D. Mislovi?ov?; M. Chudinová; A. Vikartovská; P. Gemeiner

1996-01-01

87

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

2011-08-29

88

L. D. V. measurements and investigation of flow field through radial turbine guide vanes  

SciTech Connect

The results of Laser Doppler Velocimeter (LDV) measurements and investigation of detailed flow field through radial inflow turbine guide vanes are presented. The flow velocities were measured at five stations upstream, inside and downstream of the guide vanes for two different mass flow rates. Data was collected at 600 points in total. A three-component LDV system was used for the velocity measurements. The results are presented as contour plots of mean velocities, flow angles, and turbulent stresses. Significant end-wall cross flows were observed inside the blade passages close to the trailing edges. However, these cross flows are different from the ones in axial turbines because of the counter effects of the radial pressure gradient, the blade shape, and the high negative incidence angle. The flow field through the blade passages was found to be strongly influenced by the scroll geometry. The lack of periodicity between flow channels and asymmetry with respect to the two end walls were attributed to this upstream influence. In addition to the experimental investigation, an analytical study of the flow field through the guide vanes of the turbine was performed. Agreement between the experimental and numerical results is satisfactory.

Eroglu, H.

1988-01-01

89

Simulation of heat transfer to flow in radial grooves of friction pairs  

NASA Astrophysics Data System (ADS)

The naphthalene sublimation technique and numerical solution of the governing equations are used to study the mechanism of heat transfer in the radial grooves of cooled disc friction pairs. It is shown that a main eddy generated by the relative motion of the friction pair creates an effective mechanism of heat transfer to the fluid flowing in the radial grooves. The effect of Coriolis forces and a thin film separating the plates on the heat transfer coefficient are investigated. Numerical and experimental Sherwood numbers for mass transfer agree to within the estimated experimental accuracy of 12%. Sample numerical results are used to describe the detailed behavior of the system.

Payvar, Parviz; Lee, Y. N.; Minkowycz, W. J.

1994-01-01

90

Non-radial solar wind flows and IMF B z during 1973-2003  

NASA Astrophysics Data System (ADS)

The characteristics of latitudinal angles of solar wind flow ( ?v) observed near earth have been studied during the period 1973-2003. The average magnitude of ?v shows distinct enhancements during the declining and maximum phases of the sunspot cycles. A close association of B z component of IMF in the GSE system and the orientation of meridional flows in the solar wind is found which depends on the IMF sector polarity. This effect has been studied in typical geomagnetic storm periods. The occurrence of non-radial flows is also found to exhibit heliolatitudinal dependence during the years 1975 and 1985 as a characteristic feature of non-radial solar wind expansion from polar coronal holes.

Pereira, Felix B.; Girish, T. E.

2009-03-01

91

Radial Spreading of Drift-Wave-Zonal-Flow Turbulence via Soliton Formation  

SciTech Connect

The self-consistent spatiotemporal evolution of a drift-wave (DW) radial envelope and a zonal-flow (ZF) amplitude is investigated in a slab model. The stationary solution of the coupled partial differential equations in a simple limit yields the formation of DW-ZF soliton structures, which propagate radially with speed depending on the envelope peak amplitude. Additional interesting physics, e.g., the generation, destruction, collision, and reflection of solitons, as well as turbulence bursting can also be observed due to the effects of linear growth or damping, dissipation, equilibrium nonuniformities and soliton dynamics. The propagation of soliton causes significant radial spreading of DW turbulence and therefore can affect transport scaling with the system size by broadening of the turbulent region. The correspondence of the present analysis with the description of DW-ZF interactions in toroidal geometry is also discussed.

Guo Zehua [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Chen Liu [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Institute for Fusion Theory and Simulation, Zhe Jiang University, Hangzhou, Zhejiang (China); Zonca, Fulvio [Associazione EURATOM-ENEA sulla Fusione, C.P. 65-00044 Frascati (Italy)

2009-07-31

92

Optimization and scale up of the adsorption fractionation of cod pyloric caeca deoxyribonuclease using axial and radial flow columns.  

PubMed

The key step in the purification of a deoxyribonuclease (DNase) from extracts of cod (Gadus morhua L.) pyloric caeca, is the selective retention of the enzyme by anion exchange chromatography. The cod DNase purification on Q-Sepharose Fast Flow (Pharmacia) was optimized, using a 60 ml fixed-bed column. In combination with titration curve analysis, we have screened the effect of buffer pHs, feed conductivity and protein loading, on the product recovery and purity. We have developed elution conditions which allow effective separation of the cod DNase from bounded impurities, such as proteinases and nucleic acids. Low levels of these impurities were regarded as essential for the desired product quality. The optimum resolution and maximum purification (ca. 20-fold increase in specific activity) of DNase, was, however, achieved at low protein loading (2.6 mg ml-1 gel), corresponding to less than 4% of the dynamic bed capacity. Scale-up to a 2.5 l pilot scale column (axial flow) and a 0.25 l radial flow column showed that the separation and yield obtained at laboratory scale was retained, and was independent of column geometry and bed height. The implications for a production scale scenario of 100 g of fractionated protein, are also discussed, as well as process hygiene. The optimization described herein adds further knowledge to the treatment of fish waste and the downstream processing of valuable biochemicals from marine raw material. PMID:1368078

Straetkvern, K O; Raae, A J; Folkvord, K; Naess, B A; Aasen, I M

1991-01-01

93

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

PubMed

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

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

2012-08-17

94

Radial anisotropy in the European mantle: Tomographic studies explored in terms of mantle flow  

NASA Astrophysics Data System (ADS)

Previous studies have shown that radial seismic anisotropy as estimated from flow models is in good agreement with results from tomography at global scale, in particular underlying oceanic basins. However, the fit is typically poor at smaller scale lengths, particularly in tectonically complex regions. We conduct a comparative analysis of tomographically mapped and dynamically modeled radial anisotropy at the scale of Europe and the Mediterranean Basin, including three tomographic models based on different observations and/or methods. We find that adaptive-grid surface-wave tomography, with parametrization density depending locally on the spatial and azimuthal density of data coverage, leads to the seismic model closest to (albeit still far from) geodynamic predictions. The ability to map regional-scale seismic anisotropy may provide a new constraint, complementary to isotropic tomography, to the nature of upper mantle flow.

Schaefer, J. F.; Boschi, L.; Becker, T. W.; Kissling, E.

2011-12-01

95

Pre-equilibrium radial flow from central shock-wave collisions in AdS 5  

NASA Astrophysics Data System (ADS)

Using gauge/gravity duality, central ultrarelativistic nucleus-nucleus collisions are modelled as collisions of shock waves in five-dimensional asymptotic AdS space. For early times after the collision, it is possible to analytically match the metric from the past to the future light-cone. This allows extraction of the pre-equilibrium energy-momentum tensor of the strongly coupled, large N gauge theory. For central collisions, this allows qualitative statements concerning the build-up of radial flow at mid-rapidity in AA and pA collisions. We find that the early-time radial flow buildup is identical to that expected from ideal hydrodynamics with an entropy density proportional to the square root of the product of the matter densities in the individual "nuclei".

Romatschke, Paul; Hogg, J. Drew

2013-04-01

96

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

97

Effects of gaze on vection from jittering, oscillating, and purely radial optic flow  

Microsoft Academic Search

In this study, we examined the effects of different gaze types (stationary fixation, directed looking, or gaze shifting) and\\u000a gaze eccentricities (central or peripheral) on the vection induced by jittering, oscillating, and purely radial optic flow.\\u000a Contrary to proposals of eccentricity independence for vection (e.g., Post, 1988), we found that peripheral directed looking\\u000a improved vection and peripheral stationary fixation impaired

Stephen Palmisano; Juno Kim

2009-01-01

98

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

99

Stochastic models in problems of the local deformation of flowing media in radial channels  

Microsoft Academic Search

A stochastic model of the discharge process of flowing media from converging radial channels with allowance for deformation\\u000a localization is constructed on the basis of models of cellular automatic devices. Probabilities of the displacement of material\\u000a particles of the medium from one cell of the cellular automatic device to another present its principal parameter. The probabilistic\\u000a characteristics of the model

S. V. Lavrikov; A. Ph. Revuzhenko

2000-01-01

100

Incorporating radial mixing in axisymmetric streamline curvature through-flow analysis  

NASA Astrophysics Data System (ADS)

The development of governing equations for hub-to-tip streamline curvature solutions in turbomachinery passages and blade rows and incorporating viscous radial mixing is presented. Arbitrary passage geometries and quasi-orthogonal description are accounted for. Fortran program coding is carried out for the special case of unbladed, axial-flow passages. Flow solutions are obtained by iteration based on fixed streamline patterns in the meridional plane followed by further iterations involving readjustment of the streamlines until overall convergence is obtained. Simple examples are presented to illustrate the solution technique.

Grabowska, D. G.; Kavanagh, P.

1993-09-01

101

Heat transfer and friction characteristics in decaying swirl flow generated by different radial guide vane swirl generators  

Microsoft Academic Search

In radial guide vane swirl generators, the flow direction must change from the radial direction to the axial direction. This can be achieved either abruptly or by means of a fairing section, and each technique can be used in conjunction with an inserted centre body (deflecting element). This research was conducted to study the effect of the geometry of the

Mehmet Yilmaz; Omer Comakli; Sinan Yapici; O. Nuri Sara

2003-01-01

102

A Power Flow Method for Radial and Meshed Distribution Systems Including Distributed Generation and Step Voltage Regulator Modeling  

Microsoft Academic Search

This paper proposes a new power flow method for radial and meshed distribution systems. The method convert a meshed distribution system with distributed generators into an equivalent single source radial distribution system, by breaking out the tie lines and distributed generators con- nections, and by abstracting auxiliary buses to the distri- bution network. The approach goes beyond the previous works

Diego Issicaba; J. Coelho

2007-01-01

103

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

104

Flow driven by a shrouded spinning disk with axial suction and radial inflow  

NASA Astrophysics Data System (ADS)

The viscous flow confined in a finite cylinder when one endwall disk and the sidewall are spinning about the central axis is studied. We examine the internal flow when a uniform axial suction through the spinning disk and a concomitant uniform radial inflow through the spinning sidewall are imposed. The rotational Reynolds number is large and the cylinder aspect ratio is O(l). Finite-difference techniques are employed to integrate numerically the full Navier-Stokes equations. The core rotation rate, which is uniform in the axial direction, increases as the suction increases. Under a sufficiently strong suction, the core rotation rate exceeds that of the spinning disk. The flows in the core away from the sidewall are depicted well by the predictions of the infinite disk model. A physical description based on an angular momentum argument is given. Due to the presence of the sidewall, the angular velocities in finite configuration vary in the radial direction, and this variation is pronounced under a strong suction. The meridional flow patterns are displayed. When the suction is weak, the bulk of the meridional fluid transport from the sidewall to the spinning disk takes route via the boundary layer near the stationary disk. Under a strong suction, the meridional fluid transport through the main body of the flow field increases. At small and moderate radii, the radial velocities nearly vanish in the core; the axial velocities increase in magnitude as the suction increases. When the suction is strong, the dynamic effects are concentrated in the Ekman layer near the spinning disk.

Jae Min, Hyun; Jae Won, Kim

105

Flow driven by a shrouded spinning disk with axial suction and radial inflow  

NASA Astrophysics Data System (ADS)

The viscous flow confined in a finite cylinder when one endwall disk and the sidewall are spinning about the central axis is studied. We examine the internal flow when a uniform axial suction through the spinning disk and a concomitant uniform radial inflow through the spinning sidewall are imposed. The rotational Reynolds number is large and the cylinder aspect ratio is O(l). Finite-difference techniques are employed to integrate numerically the full Navier-Stokes equations. The core rotation rate, which is uniform in the axial direction, increases as the suction increases. Under a sufficiently strong suction, the core rotation rate exceeds that of the spinning disk. The flows in the core away from the sidewall are depicted well by the predictions of the infinite disk model. A physical description based on an angular momentum argument is given. Due to the presence of the sidewall, the angular velocities in finite configuration vary in the radial direction, and this variation is pronounced under a strong suction. The meridional flow patterns are displayed. When the suction is weak, the bulk of the meridional fluid transport from the sidewall to the spinning disk takes route via the boundary layer near the stationary disk. Under a strong suction, the meridional fluid transport through the main body of the flow field increases. At small and moderate radii, the radial velocities nearly vanish in the core; the axial velocities increase in magnitude as the suction increases. When the suction is strong, the dynamic effects are concentrated in the Ekman layer near the spinning disk.

Min, Hyun Jae; Won, Kim Jae

1987-12-01

106

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

107

Modeling of transient flow through a viscoelastic preparative chromatography packing.  

PubMed

The common method for purification of macromolecular bioproducts is preparative packed-bed chromatography using polymer-based, compressible, viscoelastic resins. Due to a downstream processing bottleneck, the chromatography equipment is often operated at its hydrodynamic limit. In this case, the resins may exhibit a complex behavior which results in compression-relaxation hystereses. Up to now, no modeling approach of transient flow through a chromatography packing has been made considering the viscoelasticity of the resins. The aim of the present work was to develop a novel model and compare model calculations with experimental data of two agarose-based resins. Fluid flow and bed permeability were modeled by Darcy's law and the Kozeny-Carman equation, respectively. Fluid flow was coupled to solid matrix stress via an axial force balance and a continuity equation of a deformable packing. Viscoelasticity was considered according to a Kelvin-Voigt material. The coupled equations were solved with a finite difference scheme using a deformable mesh. The model boundary conditions were preset transient pressure drop functions which resemble simulated load-/elution-/equilibration cycles. Calculations using a homogeneous model (assuming constant variables along the column height) gave a fair agreement with experimental data with regard to predicted flow rate, bed height, and compression-relaxation hysteresis for symmetric as well as asymmetric pressure drop functions. Calculations using an inhomogeneous model gave profiles of the bed porosity as a function of the bed height. In addition, the influence of medium wall support and intra-particle porosity was illustrated. The inhomogeneous model provides insights that so far are not easily experimentally accessible. © 2013 American Institute of Chemical Engineers Biotechnol. Prog.,, 2013. PMID:23757198

Hekmat, Dariusch; Kuhn, Michael; Meinhardt, Verena; Weuster-Botz, Dirk

2013-06-11

108

Modeling of transient flow through a viscoelastic preparative chromatography packing.  

PubMed

The common method for purification of macromolecular bioproducts is preparative packed-bed chromatography using polymer-based, compressible, viscoelastic resins. Because of a downstream processing bottleneck, the chromatography equipment is often operated at its hydrodynamic limit. In this case, the resins may exhibit a complex behavior which results in compression-relaxation hystereses. Up to now, no modeling approach of transient flow through a chromatography packing has been made considering the viscoelasticity of the resins. The aim of the present work was to develop a novel model and compare model calculations with experimental data of two agarose-based resins. Fluid flow and bed permeability were modeled by Darcy's law and the Kozeny-Carman equation, respectively. Fluid flow was coupled to solid matrix stress via an axial force balance and a continuity equation of a deformable packing. Viscoelasticity was considered according to a Kelvin-Voigt material. The coupled equations were solved with a finite difference scheme using a deformable mesh. The model boundary conditions were preset transient pressure drop functions which resemble simulated load/elution/equilibration cycles. Calculations using a homogeneous model (assuming constant variables along the column height) gave a fair agreement with experimental data with regard to predicted flow rate, bed height, and compression-relaxation hysteresis for symmetric as well as asymmetric pressure drop functions. Calculations using an inhomogeneous model gave profiles of the bed porosity as a function of the bed height. In addition, the influence of medium wall support and intraparticle porosity was illustrated. The inhomogeneous model provides insights that so far are not easily experimentally accessible. PMID:23798499

Hekmat, Dariusch; Kuhn, Michael; Meinhardt, Verena; Weuster-Botz, Dirk

2013-06-25

109

The role of radial particle flow on power balance in DIII-D  

NASA Astrophysics Data System (ADS)

The importance of radial particle flow on the power flowing across the last closed flux surface (separatrix) in DIII-D [Luxon et al., International Conference on Plasma Physics and Controlled Nuclear Fusion (International Atomic Energy Agency, Vienna, 1986), Vol. I, p. 159] is considered. The perpendicular thermal diffusivity at the separatrix is near 1 m2/s in low confinement operation (L-mode), and 0.1 m2/s in high confinement (H-mode). The particle diffusivity is about one-fourth of the thermal diffusivity producing radial particle fluxes of the order of kilo-amperes. The particle flux is 10 to 100 times the particle input from neutral beam sources, consistent with core fueling being dominated by neutral recycling. The radial particle flux scales with the neutral pressure in the private flux region, suggesting the core is fueled predominantly from neutrals which recycle from the divertor, through the private flux, and into the core near the singular point where the poloidal field is zero (X-point). There is significant core power loss associated with the large particle flux across the separatrix. The electron temperature measured at the top of the edge pedestal in H-mode operation scales inversely with the particle flux. In turn, the core energy confinement scales with the pedestal temperature, and hence inversely with the particle flux. The results presented here indicate the global particle confinement time is between 0.5 and 2 times the global energy confinement time.

Porter, G. D.

1998-12-01

110

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

SciTech Connect

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

Sanchez, R. [Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States); Newman, D. E. [Department of Physics, University of Alaska, Fairbanks, Alaska 99775-5920 (United States); Leboeuf, J.-N. [JNL Scientific, Inc., Casa Grande, Arizona 85294-9695 (United States); Carreras, B. A. [BACV Solutions, Inc., Oak Ridge, Tennessee 37830-8222 (United States); Decyk, V. K. [UCLA, Los Angeles, California 90095-1547 (United States)

2009-05-15

111

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

SciTech Connect

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

Sanchez, Raul [ORNL; Newman, David E [University of Alaska; Leboeuf, Jean-Noel [JNL Scientific, Inc., Casa Grande, AZ; Carreras, Benjamin A [BACV Solutions, Inc., Oak Ridge; Decyk, Viktor [University of California, Los Angeles

2009-01-01

112

Cyclic and radial variation of ultrasonic backscatter from flowing porcine blood  

NASA Astrophysics Data System (ADS)

The ultrasonic backscattering from flowing blood was investigated using several hemodynamic parameters and a physiological parameter. Acceleration was hypothesized to enhance the aggregation of red blood cells (RBCs), and this is the first time that acceleration is suggested and experimentally verified as having an effect on aggregation of RBC. Two interesting phenomena, the 'Black Hole (BH)' phenomenon and the 'Bright Collapsing Ring (BCR)' phenomenon, were observed under pulsatile flow in B-mode cross sectional images. The BH phenomenon describes a dark hypoechoic hole at the center of the tube surrounded by a bright hyperechoic zone in B-mode cross sectional images, and the BCR phenomenon describes the appearance of a bright hyperechoic ring at the periphery of the tube at early systole and its convergence from the periphery to the center of the tube, finally collapsing as flow develops. Doppler power variation was observed only from porcine whole blood, which led to a conclusion that the ultrasonic backscattering was mainly dependent on the RBC aggregation under steady and pulsatile flow. The pattern of the cyclic variation of the Doppler power to have a maximum power at peak systole was mainly due to the enhanced rouleaux formation by acceleration. The BCR phenomenon was observed from the cyclic variation pattern of the Doppler power at different radial positions; the Doppler power peak was observed at early systole at the periphery of the tube and lagged the flow as close from the periphery to the center of the tube. The BCR phenomenon from porcine whole blood in a mock flow loop was further examined in real time in B-mode images under pulsatile flow. At low hematocrit of 12%, no BCR phenomenon was discernable although it was observed at higher hematocrits. The pattern of the nonlinear relationship between echogenicity and hematocrit varied with radial positions. The BH phenomenon was also observed under certain hemodynamic conditions and varied over a pulsatile cycle. The BCR phenomenon was also observed from human carotid arteries from 10 subjects only in the harmonic images. In order to better understand these phenomena, the cyclic and radial variation of echogenicity under oscillatory flow was measured and the results showed a different pattern from that under pulsatile flow. (Abstract shortened by UMI.)

Paeng, Dong-Guk

113

Inertial-microfluidic radial migration in solid\\/liquid two-phase flow through a microcapillary: Particle equilibrium position  

Microsoft Academic Search

Although equilibrium of spherical particles under radial migration has been extensively investigated, mostly in macroscale\\u000a flows with characteristic lengths on the order of centimeters, it is not fully characterized at relatively small Reynolds\\u000a numbers, 1 ? Re ? 100. This paper experimentally studies “inertial microfluidic” radial migration of spherical particles in circular Poiseuille\\u000a flow through a microcapillary. Microparticle tracking experiments are performed to obtain

Young Won Kim; Hikui Noh; Songwan Jin; Jung Yul Yoo

114

Radial distribution of the flow velocity, efficiency and concentration in a wide HPLC column  

SciTech Connect

The use of optical fibers in a fluorescence-detection scheme permits the accurate determination of the radial distribution of the transit time, the column efficiency, and the analyte concentration at the exit of a chromatographic axial-compression column (50 mmID). The results obtained demonstrate that the column is not homogeneous, but suggest a nearly cylindrical distribution of the packing density. The average velocity close to the column wall is 7% lower than along its axis and the HETP 25% higher. The lack of homogeneity of the column packing is another source of band broadening not taken into account in chromatography so far. It causes the apparent HETP derived from the conventional elution chromatogram recorded on the bulk eluent to be larger than the local HETP and the band profile to be unsymmetrical with a slight tail reminiscent of kinetic tailing.

Farkas, T.; Sepaniak, M.J.; Guiochon, G. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States). Div. of Chemical and Analytical Sciences

1997-08-01

115

Microemulsion electrokinetic chromatography in suppressed electroosmotic flow environment  

Microsoft Academic Search

Microemulsion electrokinetic chromatography (MEEKC) was carried out in a pH 2.5 phosphate buffer to effectively suppress the electroosmotic flow (EOF). With 66.6% (w\\/w) 25 mM phosphate buffer pH 2.5, 20.0% (w\\/w) 2-propanol, 6.6% (w\\/w) 1-butanol, 6.0% (w\\/w) sodium lauryl sulphate (SDS), and 0.8% (w\\/w) n-octane as the separation medium, the fat-soluble vitamins A palmitate, E acetate, and D3 were baseline

Stig Pedersen-Bjergaard; Øystein Næss; Siver Moestue; Knut Einar Rasmussen

2000-01-01

116

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

117

A cubic matrix-fracture geometry model for radial tracer flow in naturally fractured reservoirs  

SciTech Connect

This study presents a general solution for the radial flow of tracers in naturally fractured reservoirs, with cubic blocks matrix-fracture geometry. Continuous and finite step injection of chemical and radioactive tracers are considered. The reservoir is treated as being composed of two regions: a mobile where dispersion and convection take place and a stagnant where only diffusion and adsorption are allowed. Radioactive decay is considered in both regions. The model of this study is thoroughly compared under proper simplified conditions to those previously presented in the literature. The coupled matrix to fracture solution in the Laplace space is numerically inverted by means of the Crump algorithm. A detailed validation of the model with respect to solutions previously presented and/or simplified physical conditions solutions (i.e., homogeneous case) or limit solutions (i.e., naturally fractured nearly homogeneous) was carried out. The influence of the three of the main dimensionless parameters that enter into the solution was carefully investigated. A comparison of results for three different naturally fractured systems, vertical fractures (linear flow), horizontal fractures (radial flow) and the cubic geometry model of this study, is presented.

Jetzabeth Ramirez-Sabag; Fernando Samaniego V.

1992-01-01

118

Design, construction and mechanical optimisation process of electrode with radial current flow in the scala tympani.  

PubMed

A 48 contact cochlear implant electrode has been constructed for electrical stimulation of the auditory nerve. The stimulating contacts of this electrode are organised in two layers: 31 contacts on the upper surface directed towards the habenula perforata and 17 contacts connected together as one longitudinal contact on the underside. The design of the electrode carrier aims to make radial current flow possible in the cochlea. The mechanical structure of the newly designed electrode was optimised to obtain maximal insertion depth. Electrode insertion tests were performed in a transparent acrylic model of the human cochlea. PMID:12948557

Deman, P R; Kaiser, T M; Dirckx, J J; Offeciers, F E; Peeters, S A

2003-09-30

119

Demonstration of the Feasibility of Radially Compressed Microbore HPLC Columns  

Microsoft Academic Search

This work involved the development of radially compressed, microbore high performance liquid chromatography (HPLC) columns. The design of the overall system and the column are described, and the problems associated with the design features are reported. Variables examined during the course of this work included the column material, column length, packing method, flow rate, radial compression pressure, and internal column

P. A. Hyldburg; C. M. Sparacino; J. W. Hines; C. D. Keller

1987-01-01

120

Chromatography.  

ERIC Educational Resources Information Center

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

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

121

Analysis of radial distribution systems with embedded series FACTS devices using a fast line flow-based algorithm  

Microsoft Academic Search

Analysis of radial distribution systems with embedded series Flexible AC Transmission System (FACTS) devices is facilitated by a formulation of power flow equations with bus voltage magnitudes and line flows as independent variables. Since control variables such as the line and bus reactive powers figure directly in the formulation, handling the control action of FACTS devices in distribution systems is

Ping Yan; Arun Sekar

2005-01-01

122

Radial-radial single rotor turbine  

DOEpatents

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

Platts, David A. (Los Alamos, NM)

2006-05-16

123

NUMERICAL SIMULATION OF HOT ACCRETION FLOWS. I. A LARGE RADIAL DYNAMICAL RANGE AND THE DENSITY PROFILE OF ACCRETION FLOW  

SciTech Connect

Numerical simulations of hot accretion flow, both hydrodynamical and magnetohydrodynamical, have shown that the mass accretion rate decreases with decreasing radius; consequently, the density profile of accretion flow becomes flatter than in the case of a constant accretion rate. This result has important theoretical and observational implications. However, because of technical difficulties, the radial dynamic range in almost all previous simulations usually spans at most two orders of magnitude. This small dynamical range, combined with the effects of boundary conditions, makes the simulation results suspect. In particular, the radial profiles of density and inflow rate may not be precise enough to be used to compare with observations. In this paper, we present a ''two-zone'' approach to expand the radial dynamical range from two to four orders of magnitude. We confirm previous results and find that from r{sub s} to 10{sup 4} r{sub s} the radial profiles of accretion rate and density can be well described by M-dot (r){proportional_to}r{sup s} and {rho}{proportional_to}r {sup -p}. The values of (s, p) are (0.48, 0.65) and (0.4, 0.85) for the viscous parameters {alpha} = 0.001 and {alpha} = 0.01, respectively. More precisely, the accretion rate is constant (i.e., s = 0) within {approx}10r{sub s}, but beyond 10r{sub s} we have s = 0.65 and 0.54 for {alpha} = 0.001 and 0.01, respectively. We find that the values of both s and p are similar in all numerical simulation works irrespective of whether a magnetic field is included or not and what kind of initial conditions are adopted. Such an apparently surprising ''common'' result can be explained by the most recent version of the adiabatic inflow-outflow model. The density profile we obtain is in good quantitative agreement with that obtained from the detailed observations and modeling of Sgr A* and NGC 3115. The origin and implications of such a profile will be investigated in a subsequent paper.

Yuan Feng; Wu Maochun; Bu Defu, E-mail: fyuan@shao.ac.cn, E-mail: mcwu@shao.ac.cn, E-mail: dfbu@shao.ac.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

2012-12-20

124

Subdiffusive radial transport in a gyrokinetic Z-pinch plasma with zonal flows  

NASA Astrophysics Data System (ADS)

We report on numerical gyrokinetic studies of a confined, magnetized plasma in a Z-pinch configuration. Building upon previous resultsfootnotetextRicci et al PRL 97 245001 2006 for the entropy mode in a gyrokinetic Z-pinch, we examine the details of particle transport as diagnosed by the displacements of an ensemble of tracer particles in simulationsfootnotetextBroemstrup, Thesis University of Maryland. The density-gradient driven entropy mode of instability leads to vertical zonal flow structures in the turbulence that impede particle transport in the radial direction. Tracer displacements in this study point to the existence of subdiffusive radial transport, such that the spreading of the tracers proceeds more slowly than predicted by a canonical turbulent diffusion equation. The relevance of this result to the usual predictions of confinement-time scaling for fusion machines is examined. We compare the effects of collisions and several values of the density gradient for significant periods of time, measured in vthermal/L. We use continuous-time random walk and fractional diffusion equation models to understand the transport process more generally. The importance of long-range velocity correlations and scale-free transport is considered.

Gustafson, Kyle; Dorland, William

2009-11-01

125

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

SciTech Connect

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

Jordan, T.H.; Puster, P. (Massachusetts Institute of Technology, Cambridge, MA (United States)); Glatzmaier, G.A. (Los Alamos National Lab., NM (United States)); Tackley, P.J. (California Institute of Technology, Pasadena, CA (United States))

1993-09-10

126

Perception of heading speed from radial flow depends on visual field  

NASA Astrophysics Data System (ADS)

We investigated the effects that the visual field has on the perception of heading speed. The stimulus was a radial flow pattern simulating a translational motion through a cylindrical tunnel. Observers evaluated the perception of heading speed by using a temporal two-alternative forced choice (2AFC) staircase method. In the first experiment, we manipulated the stimulus area by cutting the visual field along the longitudinal direction. The results showed that the perceived heading speed increases with the stimulus area. In the second experiment, we manipulated both the stimulus area and the eccentricity by cutting the visual field along the longitudinal direction. The results showed that the perception of heading speed increases when the stimulus occupies a large portion of the peripheral visual field. These findings suggest that the effect of eccentricity is a consequence of an incorrect translation of two-dimensional visual information into three-dimensional scaling.

Segawa, Kaori; Ujike, Hiroyasu; Okajima, Katsunori; Saida, Shinya

2012-07-01

127

Micellar electrokinetic chromatography in zero-electroosmotic flow environment.  

PubMed

Micellar electrokinetic chromatography (MEKC) is conducted in polyacrylamide-coated capillaries under almost complete suppression of electroosmotic flow. The equations of migration and resolution for neutral solutes in this mode of MEKC operation are presented. The technique is termed reversed-flow MEKC (RF-MEKC) because, in contrast to MEKC in bare-silica capillaries (N-MEKC), solute migration order is reversed and solute migration time is inversely proportional to micelle concentration. This presents an advantage for the high-efficiency separation of extremely and moderately hydrophobic solutes in a short analysis time. Examples of the separation of polycyclic aromatic hydrocarbons, aflatoxins and dansylated-amino acids are presented using sodium dodecyl sulfate (SDS) surfactant. Polycyclic aromatic hydrocarbons are separated using a relatively low micelle concentration. The detection sensitivity for these compounds is enhanced in two ways. First, the peaks are sharp because of the short analysis time and the inertness of the column surface. Second, the fluorescence background and Joule's heating are minimal because of the low concentration of SDS and other additives needed to affect the separation. While N-MEKC is mainly conducted with basic buffers, RF-MEKC can be conducted in basic as well as acidic media as illustrated in the separation of 15 dansylated-amino acids at pH 4.2. PMID:8876436

Janini, G M; Muschik, G M; Issaq, H J

1996-08-01

128

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

129

Large eddy simulation of flow and heat transfer of an impinging radial jet  

NASA Astrophysics Data System (ADS)

LES with a dynamic SGS model of impinging axial and radial jets are compared to determine why radial jets with an exit angle ? 60° give larger heat transfer than the axial jet. The reason lies in the highly agitating nature of the "dead water" zone below the feed tube of the radial jet. LES captures this phenomenon correctly.

Cziesla, T.; Chattopadhyay, H.; Mitra, N. K.

130

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

131

Rotation-induced heat transfer in a radial flow passage in a rotating shaft  

NASA Astrophysics Data System (ADS)

Experiments have been performed to determine the heat transfer characteristics for rotation-induced flow in a radial passage in a shaft rotating about its own axis. The experiments encompassed passages whose ends were either flush with the surface of the shaft or protruded beyond the surface. For the latter, the passage was either centered in the shaft or else was offset such that the respective ends protruded different distances from the shaft surface. In the main body of experiments, both ends of the passage were open. Supplementary experiments with only one open end and others with an internal blockage were carried out to gain insight into the pattern of fluid flow. When the passage was centered in the shaft, there was negligible fluid throughflow, but even a small offset gave rise to a significant throughflow. For the centered case, the heat transfer coefficient was insensitive to whether the passage did or did not protrude beyond the shaft. Offsetting of the passage provided significant heat transfer enhancement relative to the centered case, and even a slight offset doubled the heat transfer coefficient.

Sparrow, E. M.; Hossfeld, L. M.

1985-03-01

132

Convergence of the backward\\/forward sweep method for the load-flow analysis of radial distribution systems  

Microsoft Academic Search

This paper presents a study on the convergence characteristics of the backward\\/forward sweep method, which is one of the most effective methods for the load-flow analysis of the radial distribution systems. After revisiting the theoretical background, the convergence conditions and the evolution of the iterative process are investigated in detail for different load models. A dedicated study of the properties

E. Bompard; E. Carpaneto; G. Chicco; R. Napoli

2000-01-01

133

Effects of water level fluctuation on radial oxygen loss, root porosity, and nitrogen removal in subsurface vertical flow wetland mesocosms  

Microsoft Academic Search

Laboratory experiments were conducted to investigate the effects of water level fluctuation on plant radial oxygen loss (ROL), root porosity, plant growth performance, and nitrogen dynamics in vertical subsurface flow wetland mesocosms. Four types of mesocosms were used: control with static water level, control with fluctuating water level, static water level with plants, and fluctuating water level with plants. Typha

S. Sasikala; Norio Tanaka; H. S. Y. Wah Wah; K. B. S. N. Jinadasa

2009-01-01

134

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, Jr. , J. J.

2001-01-01

135

Mechanism research on air mass flow rate distribution in rotor radial ducts of turbo generator with sub-slot ventilation  

Microsoft Academic Search

In order to reduce the axial temperature difference and the peak temperature in the rotor of the large turbo generator with air-coolant, it is expected that ventilation is uniform in rotor radial ducts along the sub-slot as far as possible. Three dimensional discrete equations of air turbulent flow in cooling duct were carried out by the Finite Volume Method according

Yiping Lu; Wenhao Yin; Pengfei Chen; Weili Li

2008-01-01

136

Radial dispersion of red blood cells in blood flowing through glass capillaries: The role of hematocrit and geometry  

Microsoft Academic Search

The flow properties of blood in the microcirculation depend strongly on the hematocrit (Hct), microvessel geometry, and cell properties. Previous in vitro studies have measured the radial displacement of red blood cells (RBCs) at concentrated suspensions using conventional microscopes. However, to measure the RBCs motion they used transparent suspensions of ghost red cells, which may have different physical properties than

Rui Lima; Takuji Ishikawa; Yohsuke Imai; Motohiro Takeda; Shigeo Wada; Takami Yamaguchi

2008-01-01

137

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

NASA Astrophysics Data System (ADS)

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

Guillou, Erwann

138

Two-dimensional Laplace-transformed power series solution for solute transport in a radially convergent flow field  

Microsoft Academic Search

This paper presents an analytical solution for two-dimensional non-axisymmetric solute transport in a radially convergent flow field. We applied a Laplace-transformed power series (LTPS) technique to solve the two-dimensional advection-dispersion equation in cylindrical coordinates. The solution is compared with a numerical solution to evaluate its robustness and accuracy. The applicable Péclet number range of the developed power series solution is

Jui-Sheng Chen; Chen-Wuing Liu; Chung-Min Liao

2003-01-01

139

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

NASA Astrophysics Data System (ADS)

To derive analytical solutions for NAPL dissolution problems with radial flow.Three key factors can affect the propagating speed of an NAPL dissolution front.Three key factors can also affect the location and breakthrough time of an NAPL dissolution front.The Zhao number can be used to represent the overall hydrodynamic characteristic of a NAPL dissolution system.Several key factors can also affect the distribution pattern and evolution of the NAPL dissolution front.

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

2013-06-01

140

Implementing transformer nodal admittance matrices into backward\\/forward sweep-based power flow analysis for unbalanced radial distribution systems  

Microsoft Academic Search

This paper proposes a new method to handle distribution transformers of various winding connections in the backward\\/forward sweep-based power flow analysis for unbalanced radial distribution systems. The method takes advantage of available nodal admittance matrices of distribution transformers, and can automatically solve the problem of conductively isolated subnetworks to obtain their equivalent phase-to-reference voltages. In addition, this paper presents a

Zhuding Wang; Fen Chen; Jingui Li

2004-01-01

141

Incorporating Radial Mixing in Axisymmetric Streamline Curvature Through-Flow Analysis.  

National Technical Information Service (NTIS)

The development of governing equations for hub-to-tip streamline curvature solutions in turbomachinery passages and blade rows and incorporating viscous radial mixing is presented. Arbitrary passage geometries and quasi-orthogonal description are accounte...

D. G. Grabowska P. Kavanagh

1993-01-01

142

Retention in multistep programmed-temperature gas chromatography and flow control Linear head pressure programs  

Microsoft Academic Search

A comparative study of retention in different systems of flow control that provide linear dependence with the temperature of the column's head pressure is performed by numerical simulation considering multistep (or multiramp) PTGC (programmed-temperature gas chromatography) as the most general situation. Calculation algorithms for each flow control mode are developed on the basis of a general retention equation and the

F. R. Gonzalez; A. M. Nardillo

1997-01-01

143

Countercurrent Chromatography with Flow-Through Coil Planet Centrifuge  

Microsoft Academic Search

We have developed a new method of countercurrent chromatography which employs a vertical helical tube in the centrifugal field. The helical tube is arranged so that it does not rotate as it revolves, thus eliminating the need for rotating seals. When the gyrating tube is filled with either phase and the other phase is introduced into the tube in the

Yoichiro Ito; Robert L. Bowman

1971-01-01

144

Massive culture of human liver cancer cells in a newly developed radial flow bioreactor system: Ultrafine structure of functionally enhanced hepatocarcinoma cell lines  

Microsoft Academic Search

Summary  With a view to initiating clinical trials, cell morphology and function for a newly developed artificial liver support system\\u000a employing highly functional human liver cell line, FLC-7, cultured in a radial flow bioreactor were compared to cells grown\\u000a in a conventional monolayer culture.\\u000a \\u000a The radial flow bioreactor consists of a vertically extended cylindrical matrix comprised of porous glass bead microcarriers

Masaaki Kawada; Seishi Nagamori; Hideki Aizaki; Kenichi Fukaya; Minoru Niiya; Tomokazu Matsuura; Hajime Sujino; Satoshi Hasumura; Hitoshi Yashida; Satoru Mizutani; Hiroshi Ikenaga

1998-01-01

145

A modified Newton method for radial distribution system power flow analysis  

Microsoft Academic Search

A modified Newton method for radial distribution systems is derived in which the Jacobian matrix is in UDUT form, where U is a constant upper triangular matrix depending solely on system topology and D is a block diagonal matrix. With this formulation, the conventional steps of forming the Jacobian matrix, LU factorization and forward\\/back substitution are replaced by back\\/forward sweeps

Fan Zhang; C. S. Cheng

1997-01-01

146

THE INFLUENCE OF ORIFICE INSERTION IN RADIAL SWIRLING FLOW FOR LOW EMISSIONS COMBUSTION  

Microsoft Academic Search

This paper presents the effect of inserting swirler outlet orifice plate of different sizes at the exit plane of the flat blade radial air swirler in liquid fuel burner system. Tests were carried out with three different orifice plates with area ratios (orifice area to swirler exit area ratio) between 1.0 to 0.7 using 280 mm inside diameter combustor of

Mohamad Shaiful Ashrul Ishak; Mohammad Nazri; Blok A; Pusat Pengajian; Seberang Ramai

2008-01-01

147

Formation producibility and fractional flow curves from radial resistivity variation caused by drilling fluid invasion  

Microsoft Academic Search

In order to characterize conductivity profiles due to drilling fluid invasion into a hydrocarbon formation, a model for radial fluid transport is presented. The model assumes a water-based mud and accounts for the convective movement of oil, water, and salt. A mathematical analysis of the model using the method of characteristics is given. An equivalent graphical construction is also provided.

T. S. Ramakrishnan; D. J. Wilkinson

1997-01-01

148

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

149

Energetic electron microsignatures as tracers of radial flows and dynamics in Saturn's innermost magnetosphere  

NASA Astrophysics Data System (ADS)

Signatures of energetic electron depletions from Saturn's inner moons (microsignatures) have been mainly utilized to infer properties of magnetospheric diffusion. The same data, however, indicate that microsignatures can be a much more powerful tool for magnetospheric studies. Here we introduce a new method where the energy structure of a microsignature can be used to trace the location, the formation date, the evolution, and the physical properties of dynamic events in the inner Saturnian magnetosphere. Application to a complex electron microsignature of Tethys, seen by Cassini's MIMI/LEMMS and CAPS/ELS detectors, reveals the location and the age of such an event. The development stages of this event, that can also be distinguished, indicate the presence of local, pulse-like azimuthal electric field variations that can locally enhance radial transport by a factor of 1000-3000 with respect to radial diffusion. We also extract several physical properties of this dynamical region and speculate about its possible nature.

Roussos, E.; Krupp, N.; Paranicas, C. P.; Mitchell, D. G.; Müller, A. L.; Kollmann, P.; Bebesi, Z.; Krimigis, S. M.; Coates, A. J.

2010-03-01

150

First-passage-time transfer functions for groundwater tracer tests conducted in radially convergent flow  

Microsoft Academic Search

Forced-gradient groundwater tracer tests may be conducted using a variety of hydraulic schemes, so it is useful to have simple semi-analytic models available that can examine various injection\\/withdrawal scenarios. Models for radially convergent tracer tests are formulated here as transfer functions, which allow complex tracer test designs to be simulated by a series of simple mathematical expressions. These mathematical expressions

Matthew W. Becker; Randall J. Charbeneau

2000-01-01

151

Radial distribution of the flow velocity, efficiency and concentration in a wide HPLC column  

Microsoft Academic Search

The use of optical fibers in a fluorescence-detection scheme permits the accurate determination of the radial distribution of the transit time, the column efficiency, and the analyte concentration at the exit of a chromatographic axial-compression column (50 mmID). The results obtained demonstrate that the column is not homogeneous, but suggest a nearly cylindrical distribution of the packing density. The average

Tivadar Farkas; Michael J. Sepaniak; Georges Guiochon

1997-01-01

152

A mathematical model linking tree sap flow dynamics to daily stem diameter fluctuations and radial stem growth.  

PubMed

To date, models for simulating sap flow dynamics in individual trees with a direct link to stem diameter variation include only the diameter fluctuation driven by a change in stem water storage. This paper reports results obtained with a comprehensive flow and storage model using whole-tree leaf transpiration as the only input variable. The model includes radial stem growth based on Lockhart's equation for irreversible cell expansion. It was demonstrated that including growth is essential to obtaining good simulation results. To model sap flow dynamics, capacitance of storage tissues was assumed either constant (i.e., electrical analogue approach) or variable and dependent on the water content of the respective storage tissue (i.e., hydraulic system approach). These approaches resulted in different shapes for the desorption curve used to calculate the capacitance of storage tissues. Comparison of these methods allowed detection of specific differences in model simulation of sap flow at the stem base (F(stem)) and stem diameter variation (D). Sensitivity analysis was performed to select a limited subset of identifiable parameters driving most of the variability in model predictions of F(stem) and D Both the electrical analogue and the hydraulic system approach for the flow and storage model were successfully calibrated and validated for the case of a young beech tree (Fagus sylvatica L.). Use of an objective model selection criterion revealed that the flow and storage model based on the electrical analogue approach yielded better predictions. PMID:16356899

Steppe, Kathy; De Pauw, Dirk J W; Lemeur, Raoul; Vanrolleghem, Peter A

2006-03-01

153

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

154

Flow Structures Associated with a Near-Earth Substorm Onset Observed During a Radial Conjunction between Polar and Cluster  

NASA Astrophysics Data System (ADS)

The precession of the Polar spacecraft orbit has placed its apogee (~9 Re) near the equator during 2000- 2003, allowing correlative studies of electric fields and plasmas between Polar and the satellites of the Cluster constellation (apogee ~19 Re). This has allowed us to preview the sorts of radial and azimuthal alignments planned for the inner satellites of the THEMIS mission, and to better understand the relationships between the in-situ plasma and field measurements and the ground-based signatures of substorm onset. A particularly clear example of correlated, rapid, and large-amplitude electric field fluctuations associated with strong plasma flows and ground signatures of substorm onset was observed on Polar and Cluster on 20 September 2003. This particular event has features that suggest important macro- and micro-scale ramifications of the electromagnetic fluctuations associated with substorm onset in the tail. The onset of electromagnetic fluctuations and strong flows at both Polar and Cluster are close to simultaneous, indicating a onset occurring between the two spacecraft, near 13 Re downtail. Ion flows as measured by Cluster/CIS are a few hundred km/s in magnitude in a relatively high-temperature environment (~14 keV). ExB flows derived from both Polar EFI and Cluster EFW indicate much higher speed flows (several thousand km/s), consistent with the observed time delays between Polar and Cluster (The discrepancy between the CIS flows and ExB flows arise primarily from instrumental background effects in the CIS data). Significant cross-tail flows at both Polar and Cluster suggest flow diversions even over the relatively short streamlines between the onset site and the spacecraft positions.

Bonnell, J. W.; Mozer, F. S.; Lin, N.

2006-05-01

155

Particle simulations of divergent and convergent radial electron flows in cylindrical Pierce diodes  

SciTech Connect

A special class of Pierce diodes, that consists of a pair of grounded coaxial cylindrical electrodes, with electrons streaming radially between them, is studied. The full set of roots of the dispersion relation of the Pierce instability is obtained by solving the dispersion relation numerically. The nonlinear behaviour of the system is then investigated using particle simulation. It is shown that the behaviour of cylindrical systems depends on two nondimensional parameters. Linear and nonlinear properties are different for convergent and divergent configurations. Several remarkable differences between cylindrical and planar Pierce diodes are reported. {copyright} {ital 1997 American Institute of Physics.}

Alves, M.V. [Instituto Nacional de Pesquisas Espaciais, P.O. Box 515, 12201-970, Sao Jose dos Campos, SP (Brazil); Gratton, F.T.; Gnavi, G.; Moreno, C.H. [Instituto de Fisica del Plasma, CONICET, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 1, 1428 Buenos Aires (Argentina)

1997-08-01

156

Inferring emplacement processes of radial dikes at Summer Coon volcano, Colorado, from geometry and AMS-derived magma flow directions  

NASA Astrophysics Data System (ADS)

Because population centers tend to cluster around the bases of volcanoes, the most distal flank eruptions can be the most hazardous. The emplacement mechanisms of radial dikes that commonly feed these extrusions are poorly understood. Consequently, we mapped and analyzed about 20 large silicic dikes which, along with hundreds of mafic dikes, are exposed in a radial pattern at Summer Coon, an eroded stratovolcano in the eastern San Juan Mountains, Colorado. In contrast to intrusions mapped at other centers, silicic dikes at Summer Coon tend to thicken with increasing radial distance. Shallower burial depths and decreasing elastic moduli away from the center of the volcano cause an increase in the dike driving pressure, and are the most likely sources of the observed teardrop form. All silicic dikes are broken into en echelon segments dominated by right-stepping offsets. Segment geometries around the volcano do not agree with previously proposed dike segmentation mechanisms including stress field rotation, intrusion into preexisting fractures, and variations in host rock properties. Flow directions determined from measurements of anisotropy of magnetic susceptibility (AMS) at 33 sites on two different dikes suggest that offsets near the center of the volcano form when magma fills echelon fractures that opened in front of the propagating dike. Distal segments probably form by the same mechanism, however both segment tips may propagate due to higher driving pressures far from the center of the volcano. Observations from Summer Coon suggest that radial dikes rise sub-vertically from depth beneath the volcano and then propagate laterally away from the center of the volcano along a neutral buoyancy surface between the base of the edifice (which is composed of low-density volcanic rocks) and the higher-density basement. The dike will thicken with increasing radial distance, favoring more voluminous eruptions at lower elevations. Future detailed geodetic studies of active stratovolcanoes (for instance, InSAR measurements of deformation at South Sister Volcano in Oregon by Wicks and others, in review, GRL), combined with additional AMS studies of dikes from eroded volcanoes may help confirm these inferred emplacement paths.

Poland, M. P.; Fink, J. H.

2001-12-01

157

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.

2013-05-15

158

Field-flow fractionation and hydrodynamic chromatography on a microfluidic chip.  

PubMed

We present gravitational field-flow fractionation and hydrodynamic chromatography of colloids eluting through 18 ?m microchannels. Using video microscopy and mesoscopic simulations, we investigate the average retention ratio of colloids with both a large specific weight and neutral buoyancy. We consider the entire range of colloid sizes, including particles that barely fit in the microchannel and nanoscopic particles. Ideal theory predicts four operational modes, from hydrodynamic chromatography to Faxén-mode field-flow fractionation. We experimentally demonstrate, for the first time, the existence of the Faxén-mode field-flow fractionation and the transition from hydrodynamic chromatography to normal-mode field-flow fractionation. Furthermore, video microscopy and simulations show that the retention ratios are largely reduced above the steric-inversion point, causing the variation of the retention ratio in the steric- and Faxén-mode regimes to be suppressed due to increased drag. We demonstrate that theory can accurately predict retention ratios if hydrodynamic interactions with the microchannel walls (wall drag) are added to the ideal theory. Rather than limiting the applicability, these effects allow the microfluidic channel size to be tuned to ensure high selectivity. Our findings indicate that particle velocimetry methods must account for the wall-induced lag when determining flow rates in highly confining systems. PMID:23650976

Shendruk, Tyler N; Tahvildari, Radin; Catafard, Nicolas M; Andrzejewski, Lukasz; Gigault, Christian; Todd, Andrew; Gagne-Dumais, Laurent; Slater, Gary W; Godin, Michel

2013-05-29

159

Stereolabile chiral compounds: analysis by dynamic chromatography and stopped-flow methods.  

PubMed

Enantiomerization and diastereomerization reactions of chiral compounds play a major role in all aspects of chemistry spanning a wide bridge from drug development to supramolecular chemistry. Traditionally, these reactions are studied by variable-temperature NMR spectroscopy and chiroptical methods such as polarimetry. However, powerful complimentary methods based on chromatography and electrophoresis have been developed and applied to a variety of stereolabile chiral compounds. This tutorial review explains the principles, applications, and limitations of dynamic chromatography and chromatographic and electrophoretic stopped-flow analysis for the investigation of isomerization reactions of chiral compounds. PMID:15965541

Wolf, Christian

2005-04-25

160

Steady and pulsating flow efficiency of a waste-gated turbocharger radial flow turbine for automotive application  

Microsoft Academic Search

In the paper the results of an experimental investigation developed on a small turbocharger turbine for automotive application are presented, including the effect of the waste-gate valve opening. The study was focused on the evaluation of turbine efficiency, especially under unsteady flow conditions typically occurring in automotive turbocharged engines. Turbine efficiency values measured under steady and pulsating flow conditions are

Silvia Marelli; Massimo Capobianco

2011-01-01

161

North-south asymmetry in polar coronal holes during sunspot minima and non-radial flows in the solar wind.  

NASA Astrophysics Data System (ADS)

The solar wind parameters and solar coronal structures have been analyzed during sunspot minimum periods of sunspot cycles 23 and 24. Polar coronal hole area is observed to be large in the northern hemisphere of the sun compared to that during southern hemisphere during the minimum periods of sunspot cycle 23. A helio-latitudinal dependence of density of the solar wind is observed in the northern hemisphere of the sun during this period. This phenomenon reverses during sunspot minimum periods of cycle 24. A close association of non-radial flows of solar wind with density variations is observed during the period of study. This can be explained in terms of the change in solar wind mass flux transport in the solar corona.

Pereira, Felix; Philip, Bijoy

2012-07-01

162

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

163

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

SciTech Connect

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

Engelko, V. I.; Kuznetsov, V. S. [Efremov Institute of Electrophysical Apparatus, doroga na Metallostroy 3, St. Petersburg 196641 (Russian Federation); Mueller, Georg [Forschungszentrum Karlsruhe, Institut fuer Hochleistungsimpuls- und Mikrowellentechnik, Herrmann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2009-01-15

164

Unbalance power flow calculation for a radial distribution system using forward-backward propagation algorithm  

Microsoft Academic Search

Three-phase power flow for unbalance distribution system is carried out using forward- backward propagation technique. The equivalent injection current method is employed to represent the loads and shunt admittances. The algorithm starts with mapping the distribution network to determine the forward and backward propagation paths. The backward propagation is used to calculate branch currents using the bus injection currents. The

A. Ulinuha; M. A. S. Masoum; S. M. Islam

2007-01-01

165

Chapter 21 Asymmetrical masking between radial and parallel motion flow in transparent displays  

Microsoft Academic Search

Human spatial behavior remains surprisingly accurate and stable, despite the complexities of the concurrent retinal image flow. How does visual motion analysis contribute to behavioral stability? To approach this question, we rely on current knowledge about heading perception and coherent motion extraction from animated random dot displays. This chapter presents psychophysical evidence for an asymmetry in the global visual decomposition

Marta Iordanova; Michael W. van Grünau

2001-01-01

166

Three-Dimensional Flow in Radial Turbomachinery and Its Impact on Design.  

National Technical Information Service (NTIS)

In the two papers on the 'Theory of Blade Design for Large Deflections' published in 1984, a new inverse design technique was presented for designing the shape of turbomachinery blades in three-dimensional flow. The technique involves the determination of...

C. S. Tan W. Hawthorne

1993-01-01

167

Determination of Urinary Glucose by a Flow Injection Analysis Amperometric Biosensor and Ion-Exchange Chromatography  

Microsoft Academic Search

A practical biosensor system has been developed for the determination of urinary glucose using a flow-injection analysis (FIA)\\u000a amperometric detector and ion-exchange chromatography. Glucose oxidase was immobilized onto porous aminopropyl glass beads\\u000a via glutaraldehyde activation to form an immobilized enzyme column. On the basis of its negative charge at pH 5.5, endogenous\\u000a urate in urine samples was effectively retained by

K. B. Male; J. H. T. Luong

1992-01-01

168

Experimental investigation of the flow around a radially vibrating circular cylinder  

NASA Astrophysics Data System (ADS)

This work aims to develop a process for controlling a cylinder wake, especially the von Karman vortex street, in such way so as to drastically reduce the drag coefficient. A new technique for influencing the cylinder wake is proposed in the present experimental study. The flow around a circular cylinder is perturbed by temporarily changing the cylinder diameter. Experiments have been performed for Reynolds numbers in the range Re=9,500 to Re=31,500. Three values of the controlling frequencies are considered: fs1=0.41, fs2=0.54 and fs3=0.73, in addition to the stationary case corresponding to a non-deformable cylinder, fs0=0. The visualisation flow shows that the pulsing motion of the cylinder walls greatly influences both the near and far wake dynamics. A decrease of the drag is expected.

Oualli, H.; Hanchi, S.; Bouabdallah, A.; Askovic, R.

2004-12-01

169

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

Microsoft Academic Search

Flow inhomogeneity and axial development in low-pressure chromatographic columns have been studied by magnetic resonance imaging velocimetry. The columns studied included (a) an 11.7-mm I.D. column packed with either 50 ?m diameter porous polyacrylamide, or 99 or 780 ?m diameter impermeable polystyrene beads, and (b) a 5-mm I.D. column commercially packed with 10 ?m polymeric beads. The packing methods included

Karthik Raghavan; Stephen J Gibbs

2002-01-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

171

Three-Dimensional Dynamics of Solar Coronal Mass Ejections: Radial and Transverse Expansion in an Asymmetric Ambient Flow Field  

NASA Astrophysics Data System (ADS)

The magnetic field structure underlying coronal mass ejections (CMEs) is that of a 3D magnetic flux rope with its fixed footpoints anchored in the photosphere. The momentum of an expanding flux rope is coupled to the ambient plasma via drag. The corona and solar wind plasma is characterized by a radially outward flow field so that the dominant flow is parallel to the motion of the apex of an expanding CME flux rope but is orthogonal to the expansion in the transverse direction. The gravitational force is also parallel to the apex motion and orthogonal to the transverse expansion motion. Thus, the apex and the flanks experience significantly different drag and gravity forces and therefore different net force. We have extended the existing erupting flux rope (EFR) model of CMEs, which assumes the toroidal axis of the expansion flux rope to be a segment of circular arc with two fixed footpoints, to self-consistently calculate the forces acting on the apex and the flanks. This extension allows one to calculate the coupled expansion for the apex and flanks. We characterize the resulting structure with a semi-major axis and semi-minor radii, i.e., as an ellipse. It is shown that the 3D dynamics are critically determined by the inductance of the new geometry.

Kunkel, Valbona; Chen, James

2012-10-01

172

Weak Radial Artery Pulse  

PubMed Central

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

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

2012-01-01

173

Nitric oxide is not obligatory for radial artery flow-mediated dilation following release of 5 or 10 min distal occlusion  

Microsoft Academic Search

This study investigated the nitric oxide (NO) dependence of radial artery (RA) flow-mediated dilation (FMD) in response to three different reactive hyperemia (RH) shear stimulus profiles. Ten healthy males underwent the following three RH trials: 1) 5 min occlusion (5 trial), 2) 10 min occlusion (10 trial), and 3) 10 min occlusion with cuff reinflation at 30 s (10–30 trial).

Kyra Pyke; Daniel J Green; Cara Weisbrod; Matthew Best; Lawrence Dembo; Gerry ODriscoll; Michael Tschakovsky

2010-01-01

174

Study of flow fractionation characteristics of magnetic chromatography utilizing high-temperature superconducting bulk magnet  

NASA Astrophysics Data System (ADS)

We present numerical simulation of separating magnetic particles with different magnetic susceptibilities by magnetic chromatography using a high-temperature superconducting bulk magnet. The transient transport is numerically simulated for two kinds of particles having different magnetic susceptibilities. The time evolutions were calculated for the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field. The field is produced by the highly magnetized high-temperature superconducting bulk magnet. The numerical results show the flow velocity difference of the particle transport corresponding to the difference in the magnetic susceptibility, as well as the possible separation of paramagnetic particles of 20 nm diameter.

Fukui, Satoshi; Shoji, Yoshihiro; Ogawa, Jun; Oka, Tetsuo; Yamaguchi, Mitsugi; Sato, Takao; Ooizumi, Manabu; Imaizumi, Hiroshi; Ohara, Takeshi

2009-01-01

175

A reversed-flow differential flow modulator for comprehensive two-dimensional gas chromatography.  

PubMed

A simple and reliable differential flow modulator has been demonstrated which reverses the flow during the flush step. The modulator is constructed with commercially available capillary flow technology tees which simplifies the apparatus and permits wide range of column dimensions to be used because the modulator volume is adjustable. Using a reverse flush arrangement the tailing of the peak at the base (baseline rise between modulations) is reduced 10-20 fold as compared to forward flush modulation. This is most easily observed for peaks overloaded in the first dimension. Excellent reproducibility (<2% RSD) of area measurements has been demonstrated with a complex fragrance sample as well as the capacity to handle significant overloading without loss of resolution in the second dimension. Further demonstrating the flexibility of this modulator, separation of C1-6 alkanes and olefins are demonstrated with two porous layer open tubular columns. PMID:22192563

Griffith, James F; Winniford, William L; Sun, Kefu; Edam, Rob; Luong, Jim C

2011-12-04

176

Consideration of the tube radial distribution of the carrier solvents in a capillary tube under laminar flow conditions and computer simulation.  

PubMed

When the ternary mixed solvents of a water-hydrophilic/hydrophobic organic solvent mixture are delivered under microspace under laminar flow conditions, the solvent molecules are radially distributed in the microspace, and generate a major inner phase and a minor outer phase. We call this fluidic phenomenon as the tube radial distribution phenomenon (TRDP). In this paper, phase formation in the TRDP was collectively considered based on experimental data, such as the inner and outer phase formation in a microchannel under laminar flow conditions, the phase diagram for the ternary mixed solvents, the solvent-component ratios required for the TRDP, and the phase transformation in a batch vessel above atmospheric pressure, which were mainly reported in our previous papers. Furthermore, the formation of inner and outer phases in a capillary tube was simulated with the two-component solvents mixture model of water and ethyl acetate. Phase formations in capillary tubes were expressed through computer simulations. PMID:22687935

Jinno, Naoya; Masuhara, Yuji; Kobayashi, Tomoya; Tainaka, Naoya; Tanigawa, Yusuke; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

2012-01-01

177

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

PubMed

Extracellular polymeric substances (EPS) have major impact on biofouling of reverse osmosis (RO) membranes. On one hand, EPS can reduce membrane permeability and on the other, EPS production by the primary colonizers may influence their deposition and attachment rate and subsequently affect the biofouling propensity of the membrane. The role of bacterial exopolysaccharides in bacterial deposition followed by the biofouling potential of an RO membrane was evaluated using an alginate overproducing (mucoid) Pseudomonas aeruginosa. The mucoid P. aeruginosa PAOmucA22 was compared with its isogenic nonmucoid prototypic parent PAO1 microscopically in a radial stagnation point flow (RSPF) system for their bacterial deposition characteristics. Then, biofouling potential of PAO1 and PAOmucA22 was determined in a crossflow rectangular plate-and-frame membrane cell, in which the strains were cultivated on a thin-film composite, polyamide, flat RO membrane coupon (LFC-1) under laminar flow conditions. In the RSPF system, the observed deposition rate of the mucoid strain was between 5- and 10-fold lower than of the wild type using either synthetic wastewater medium (with ionic strength of 14.7 mM and pH 7.4) or 15 mM KCl solution (pH of 6.2). The slower deposition rate of the mucoid strain is explained by 5- to 25-fold increased hydrophilicity of the mucoid strain as compared to the isogenic wild type, PAO1. Corroborating with these results, a significant delay in the onset of biofouling of the RO membrane was observed when the mucoid strain was used as the membrane colonizer, in which the observed time for the induced permeate flux decline was delayed (ca. 2-fold). In conclusion, the lower initial cell attachment of the mucoid strain decelerated biofouling of the RO membrane. Bacterial deposition and attachment is a critical step in biofilm formation and governed by intimate interactions between outer membrane proteins of the bacteria and the surface. Shielding these interactions by a hydrated and hydrophilic alginate capsule is shown to dramatically lessen the biofouling potential of the membrane colonizers. PMID:19848149

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

2009-10-01

178

Calculating the Flow Field in a Radial Turbine Scroll: Finite-difference and finite-element methods give glow solutions.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. In many applications, radial turbines offer benefits over axial turbines. With advantages such as high efficiency over a range of speeds, less sensitivity to tip cle...

1984-01-01

179

[Use of reverse flow pedicled osteo-fascio-cutaneous radial forearm flap in reconstruction of the first ray in the hand].  

PubMed

A reverse flow pedicled osteo-fascio-cutanous radial forearm flap was applied in different clinical situations. Treatment of 1 female patient--age 28 years, and 3 male patient--age 17, 29 and 33 years is presented. Indications for treatment were: congenital malformation of the thenar region and thumb, deficit of the soft tissue, of the IMP joint and a segment of the first metacarpal bone, amputation of the thumb at IMP level and congenital total absence of the first ray of the hand. The author's modification of total thumb reconstruction is presented. Some steps of the procedure, using osteo-fascio-cutaneous radial flap differed from the original Biemer and Stock method. Donor site was located on the medial and radial part of the forearm. The flap was planned, elevated longitudinally and folded over the vascularized radial bone graft. In thumb reconstruction cases no implants were used for bone fixation. Part of the radius was directly nailed into the distal part of the first metacarpal. Bone healing was observed after 6 weeks and its remodeling took nearly 6 months. There were no complications at the donor site (one was closed directly and two by skin grafts). Two flaps were remodeled because of soft tissue abundance. Functional and cosmetic results were good in all four cases. PMID:11144073

Molski, M

2000-01-01

180

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

Microsoft Academic Search

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

Kimberly E. Lawrence; Gary W. Rice; Velmer A. Fassel

1984-01-01

181

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

PubMed

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

Wasim, Mohammad; Brereton, Richard G

182

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

183

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

184

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

185

Application of Turbulent Flow Chromatography Load Columns for the On-Line Analysis of Anti-Infectives in Wastewaters  

Microsoft Academic Search

We developed an on-line preconcentration liquid chromatography-tandem mass spectrometry method for the determination of the\\u000a anti-infectives sulfamethoxazole, trimethoprim, ciprofloxacin, levofloxacin, clarithromycin and azithromycin in wastewaters\\u000a using a turbulent flow chromatography load column. Recoveries for the target analytes were between 86 and 141%. Limits of\\u000a quantification ranged from 45 to 122 ng L?1 and limits of confirmation from 37 to 142 ng L?1. This study

Pedro A. Segura; Christian Gagnon; Sébastien Sauvé

2009-01-01

186

Flow injection extraction chromatography with ICP-MS for thorium and uranium determination in human body fluids  

Microsoft Academic Search

A method based on flow injection extraction chromatography coupled to on-line ICP-MS (FI-EXC-ICPMS) has been developed and\\u000a validated for simultaneous thorium and uranium determination in human body fluids. By using extraction chromatography, the\\u000a limits of detection achieved for 232Th, 235U and 238U were 0.06 ng.l-1, 0.0014 ng.l-1 and 0.05 ng.l-1, respectively. The accuracy of the FI-EXC-ICPMS method was 102.4% and

S. Yu. Tolmachyov; J. Kuwabara; H. Noguchi

2004-01-01

187

Radial Inflow Turbine Study.  

National Technical Information Service (NTIS)

The radial inflow turbine is a primary component used both in small gas turbines and turbochargers. Better understanding of the flow processes occurring within the small passages of the machine could well result in the improved design of units. As most of...

R. L. Elder S. Hami

1991-01-01

188

Radial addressing of nanowires  

Microsoft Academic Search

We introduce radial encoding of nanowires (NWs), a new method of differentiating and control- ling NWs by a small set of mesoscale wires for use in crossbar memories. We describe methods of controlling these NWs and give efficient manufacturing algorithms. These new encoding and decoding methods do not suffer from the misalignment characteristic of flow-aligned NWs. They achieve comparable effective

John E. Savage; Eric Rachlin; André Dehon; Charles M. Lieber; Yue Wu

2006-01-01

189

Stress-Field Modeling and Pressure Drop Prediction for Slug-Flow Pneumatic Conveying in an Aerated Radial Stress Chamber  

Microsoft Academic Search

Slug-flow pneumatic conveying is a full-bore mode of flow within the dense-phase flow regime where bulk materials are transported in the form of slugs at conveying speeds below saltation velocity. The mechanism of slug-flow pneumatic conveying consists of the particles being picked up from the stationary bed in front of a moving slug while the same amount of material is

T. KRULL; M. G. JONES; S. KEYS

2004-01-01

190

Time distribution of adsorption entropy of gases on heterogeneous surfaces by reversed-flow gas chromatography.  

PubMed

The reversed-flow gas chromatography (RF-GC) technique has been applied to measure the adsorption entropy over time, when gaseous pentane is adsorbed on the surface of two solids (gamma-alumina and a silica supported rhodium catalyst) at 393.15 and 413.15K, respectively. Utilizing experimental chromatographic data, this novel methodology also permits the simultaneous measurement of the local adsorption energy, epsilon, local equilibrium adsorbed concentration, c(s)(*), and local adsorption isotherm, theta(p, T, epsilon) in a time resolved way. In contrast with other inverse gas chromatographic methods, which determine the standard entropy at zero surface coverage, the present method operates over a wide range of surface coverage taking into account not only the adsorbate-adsorbent interaction, but also the adsorbate-adsorbate interaction. One of the most interesting observations of the present work is the fact that the interaction of n-pentane is spontaneous on the Rh/SiO(2) catalyst for a very short time interval compared to that on gamma-Al(2)O(3). This can explain the different kinetic behavior of each particular gas-solid system, and it can be attributed to the fact that large amounts of n-C(5)H(12) are present on the active sites of the Rh/SiO(2) catalyst compared to those on gamma-Al(2)O(3), as the local equilibrium adsorbed concentration values, c(s)(*), indicate. PMID:16806242

Katsanos, Nicholas A; Kapolos, John; Gavril, Dimitrios; Bakaoukas, Nicholas; Loukopoulos, Vassilios; Koliadima, Athanasia; Karaiskakis, George

2006-06-27

191

A liquid-junction\\/low-flow interface for sensitivity improvement in micelle electrokinetic chromatography–electrospray ionization-mass spectrometry  

Microsoft Academic Search

A liquid-junction\\/low-flow interface was used to alleviate ion suppression caused by nonvolatile surfactants in micelle electrokinetic chromatography–electrospray ionization-mass spectrometry. Ion suppression due to micelles was alleviated by adjusting operating conditions to keep micelles from entering the ESI source. Two operation modes were investigated. In the first configuration, micelles migrated in the direction opposite to the analytes of interest. A second

Yi-Lin Liu; Nan-Hsuan Wang; Fu-An Li; Guor-Rong Her

2009-01-01

192

Estimation of the quantification uncertainty from flow injection and liquid chromatography transient signals in inductively coupled plasma mass spectrometry  

Microsoft Academic Search

The quality of the quantitative results obtained from transient signals in high-performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC–ICPMS) and flow injection–inductively coupled plasma mass spectrometry (FI–ICPMS) was investigated under multielement conditions. Quantification methods were based on multiple-point calibration by simple and weighted linear regression, and double-point calibration (measurement of the baseline and one standard). An uncertainty model, which includes

Francisco Laborda; Jesús Medrano; Juan R Castillo

2004-01-01

193

Inductively coupled plasma mass spectrometric detection for multielement flow injection analysis and elemental speciation by reversed-phase liquid chromatography  

Microsoft Academic Search

The feasibility of using an inductively coupled plasma mass spectrometer as a multielement detector for flow injection analysis (FIA) and ion-pair reversed-phase liquid chromatography was investigated. Sample introduction was by ultrasonic nebulization with aerosol desolvation. Absolute detection limits for FIA ranged from 0.01 to 0.1 ng for most elements using 10-..mu..L injection. Over 30 elements were surveyed for their response

Joseph J. Thompson; R. S. Houk

1986-01-01

194

A variant of circular thin-layer chromatography with a forced flow of the mobile phase produced by an electroosmotic pump  

NASA Astrophysics Data System (ADS)

A new variant of circular thin-layer chromatography (TLC) with a closed sorption layer in which a forced flow of the mobile phase was produced and controlled by an external electroosmotic pump placed at the center of a TLC plate was suggested. It was shown experimentally that the method operated properly and could be used in planar chromatography.

Berezkin, V. G.; Nekhoroshev, G. A.

2007-11-01

195

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.

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

2011-01-01

196

Sequential Three-Phase Power Flow Calculation for Radial Distribution Systems via Three-Phase Z-Bus Distribution Factor  

Microsoft Academic Search

This paper aims to develop a sequential three-phase power flow program with three-phase ZBus distribution factor(TZBD) for power flow calculation. First, using monthly energy consumption of customers in a customer information system (CIS) and typical daily load pattern of customer classes, the quarter hourly loading profiles of distribution transformers were derived. The derived daily load curves are the loading database

Wei-Tzer Huang; Shiuan-Tai Chen

2009-01-01

197

Quantitative multi-residue method for determination antibiotics in chicken meat using turbulent flow chromatography coupled to liquid chromatography-tandem mass spectrometry.  

PubMed

A multi-class method for identification and quantification of 36 antibiotics from seven different chemical classes (aminoglycosides, macrolides, lincosamides, sulfonamides, tetracyclines, quinolones and trimethoprim) has been developed by using liquid chromatography-mass spectrometry. The method was optimised for detection of antibiotics in chicken meat. Sample preparation including extraction with a mixture of acetonitrile:2% trichloroacetic acid (45:55, v/v), centrifugation and filtration was followed by on-line clean-up using turbulent flow chromatography. Using this automated on-line technique enabled a larger number of samples to be analysed per day than with a traditional clean-up technique (e.g. solid phase extraction). The optimised method was validated according to the European Commission Directive 2002/657/EC. In-house validation was performed by fortifying the blank matrix at three levels 0.5, 1.0 and 1.5 MRL (maximum residue limit), or respectively, at concentrations as low as possible for substances without an MRL. Precision in terms of repeatability standard deviation ranged from 3 to 28% and recovery values were between 80 and 120% in most cases. All calculated validation parameters including CC? and CC? were in the compliance with the legislative requirements. PMID:23298848

Bousova, Katerina; Senyuva, Hamide; Mittendorf, Klaus

2012-12-19

198

Small-Scale Flow Structures Associated with a Near-Earth Substorm Onset Observed During a Radial Conjunction between Polar and Cluster  

NASA Astrophysics Data System (ADS)

The precession of the Polar spacecraft orbit has placed its apogee (~9 Re) near the equator during 2000-2003, allowing correlative studies of electric fields and plasmas between Polar and the satellites of the Cluster constellation (apogee ~19 Re). This has allowed us to preview the sorts of radial and azimuthal alignments planned for the inner satellites of the THEMIS mission, and to better understand the relationships between the in-situ plasma and field measurements and the ground-based signatures of substorm onset. A particularly clear example of correlated, rapid, and large-amplitude electric field fluctuations associated with strong plasma flows and ground signatures of substorm onset was observed on Polar and Cluster on 20 September 2003. This particular event has features that suggest important macro- and micro-scale ramifications of the electromagnetic fluctuations associated with substorm onset in the tail. The onset of electromagnetic fluctuations and strong flows at both Polar and Cluster are close to simultaneous, indicating a onset occurring between the two spacecraft, near 13 Re downtail. Ion temperatures Ion flows as measured by Cluster/CIS are a few hundred km/s in magnitude in a relatively high-temperature environment (~14 keV). ExB flows derived from both Polar EFI and Cluster EFW indicate much higher speed flows (1000 km/s), consistent with the observed time delays between Polar and Cluster. The relative amplitudes of the electric and magnetic fluctuations during the event indicate that significant small-scale structure below the acoustic gyroradius exists within these flows. Such small-scale structure can lead to local stochastic ion acceleration, and may also serve as a source for the observed sub-inertial perpendicular scale structure at auroral altitudes.

Bonnell, J. W.; Mozer, F. S.; Lin, N.

2005-12-01

199

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

NASA Astrophysics Data System (ADS)

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

Ikeshita, Kazuki; Hasegawa, Hideyuki; Kanai, Hiroshi

2012-07-01

200

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

201

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

2012-08-01

202

Zonal rate model for stacked membrane chromatography. I: Characterizing solute dispersion under flow-through conditions  

Microsoft Academic Search

Conventional models of both packed-bed and stacked-membrane chromatography typically attribute elution band broadening to non-idealities within the column. However, when the column length to diameter ratio is greatly reduced, as in stacked-membrane chromatography, variations in solute residence times within the feed-distribution (inlet) and eluent-collection (outlet) manifolds can also contribute to band broadening. We report on a new zonal rate model

Patrick Francis; Eric von Lieres; Charles A. Haynes

2011-01-01

203

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

NASA Astrophysics Data System (ADS)

We analyze conservative solute transport under convergent flow to a well in perfectly stratified porous media, in which the hydraulic conductivity is treated as a random spatial function along the vertical direction (K(z)). The stratified model provides a rare exception of an exact analytical solution of travel time distributions in the proximity of pumping wells, and it is used here to obtain insights about ergodic and nonergodic transport conditions under nonuniform flow conditions. In addition, it provides a benchmark for numerical models aiming to correctly reproduce convergent flow transport in heterogeneous media, such as indicating the minimum number of layers required to obtain ergodic travel time distributions using only one model realization. The model provides important insights about the shape of the depth-integrated concentrations over time measured at the well (breakthrough curves, BTCs), which are usually applied to obtain transport parameters of the subsurface. It can be applied to any degree of system's heterogeneity and using either resident or flux-weighted injection modes. It can be built using different probabilistic distributions of K. In our analysis, we consider a log-normal K distribution, and the results indicate that, especially for highly heterogeneous systems, described by the log-K variance (?Y2), the minimum number of layers required for from one model simulation to reproduce ergodic travel time distributions can be prohibitively high, e.g., above 106 for ?Y2=8 considering flux-weighted injections. This issue poses serious concerns for numerical applications aiming to simulate transport in the proximity of pumping wells. In addition, this simple solution confirms that stratification can lead BTCs to display strong preferential flow and persistent, power-law-like late-time tailing. Since the latter are common phenomenological macroscale evidences of other microscale hydrodynamic processes than pure advection (e.g., mass-transfer), caution must be taken when inferring aquifer properties controlling the anomalous transport dynamics in heterogeneous media from BTCs fitting.

Pedretti, Daniele; Fiori, Aldo

2013-10-01

204

Impact of the BEA zeolite morphology on isobutane adsorption followed by Reversed-Flow Inverse Gas Chromatography.  

PubMed

The mass transfer phenomena of isobutane (i-C4) were investigated at 343K on three protonic BEA zeolites. Defined by their crystallites sizes and degrees of aggregation, these samples were characterized by Reversed-Flow Inverse Gas Chromatography (RF-GC). This simple technique, used in conjunction with numerical computation, allowed the determination of physicochemical quantities like local monolayer capacities, probability density functions and diffusion coefficients in a time-resolved way. This study enabled to conclude that the effective diffusion coefficient was affected by the size of the zeolite agglomerate whereas the surface diffusion depended on the zeolite crystallite size. PMID:22964049

Batalha, N; Soualah, A; Pinard, L; Pouilloux, Y; Lemos, F; Belin, T

2012-08-30

205

Oxidation of element 102, nobelium, with flow electrolytic column chromatography on an atom-at-a-time scale.  

PubMed

We report here on the successful oxidation of element 102, nobelium (No), on an atom-at-a-time scale in 0.1 M alpha-hydroxyisobutyric acid (alpha-HIB) solution using a newly developed technique, flow electrolytic column chromatography. It is found that the most stable ion, No(2+), is oxidized to No(3+) within 3 min and that the oxidized No complex with alpha-HIB holds the trivalent state in the column above an applied potential of 1.0 V. PMID:19514720

Toyoshima, Atsushi; Kasamatsu, Yoshitaka; Tsukada, Kazuaki; Asai, Masato; Kitatsuji, Yoshihiro; Ishii, Yasuo; Toume, Hayato; Nishinaka, Ichiro; Haba, Hiromitsu; Ooe, Kazuhiro; Sato, Wataru; Shinohara, Atsushi; Akiyama, Kazuhiko; Nagame, Yuichiro

2009-07-01

206

Radial Inflow Turboexpander Redesign  

SciTech Connect

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

William G. Price

2001-09-24

207

Distributed generation modeling for power flow studies and a three-phase unbalanced power flow solution for radial distribution systems considering distributed generation  

Microsoft Academic Search

Distributed generations (DGs) are generally modeled as PV or PQ nodes in power flow studies (PFSs) for distribution system. Determining a suitable model for each DG unit requires knowing the DG operation and the type of its connection to the grid (direct or indirect). In this respect, this paper offers a helpful list of DG models for PFSs. Moreover, an

S. M. Moghaddas-Tafreshi; Elahe Mashhour

2009-01-01

208

Simulations of the Neutral-beam-induced Rotation, Radial Electric Field, and Flow Shearing Rate in Next-step Burning Plasmas  

SciTech Connect

Toroidal rotation of plasmas in present tokamaks is beneficial for increasing the stability to wall-induced MHD and appears to reduce the anomalous transport associated with micro-turbulence. This paper calculates the toroidal rotation expected from neutral-beam injection in the proposed FIRE and ITER-FEAT tokamak reactors. Self-consistent burning plasmas for these tokamaks have been constructed using the TRANSP plasma analysis code. Neutral-beam injection has been proposed for FIRE and ITER-FEAT. The neutral-beam-induced torques are computed, and assumptions for the anomalous transport of toroidal angular momentum are used to calculate the toroidal rotation profiles. The central Mach numbers are about 3-8%. The ratio of the rotation speed to the Alfvin speed is less than 1%. Assuming neoclassical poloidal rotation and force balance, the radial electric field and flow shearing rate are calculated. Peak shearing rates near the outboard edge are in the 10-100 krad/s range.

R.V. Budny

2002-08-13

209

Radial inflow turbine study  

NASA Astrophysics Data System (ADS)

The radial inflow turbine is a primary component used both in small gas turbines and turbochargers. Better understanding of the flow processes occurring within the small passages of the machine could well result in the improved design of units. As most of the detailed aerodynamics is still ill-defined, a joint research project with the objective of improving our understanding has been instigated by Cranfield, the US Army and Turbomach (San Diego). This document gives the seventh report on the project and describes progress and measurements taken.

Hamid, S.; Elder, R. L.

1992-03-01

210

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.

211

On the determination of a detector response enhancement factor for flow modulated comprehensive two-dimensional gas chromatography.  

PubMed

Comparison of conventional one-dimensional gas chromatography (1D-GC) and comprehensive two-dimensional gas chromatography (GC×GC) shows that the detector signal in GC×GC is significantly enhanced. The value of this enhancement depends on the operating parameters, such as the modulation time and the non-modulated ((1)D column) and corresponding modulated ((2)D column) peak widths. Determination of the enhance factors in flow modulated GC×GC for separation of hydrocarbon samples using flame ionization detection (FM GC×GC-FID) was studied. A term named detector response enhance factor (DREF) has been designed to express the value of the signal enhancement. Two methods were used to calculate DREF: (i) employing (2)D peak height, and (ii) using a theoretical approach. Comparison of FM GC×GC-FID and 1D-GC-FID method illustrates that the DREF increases from 10 to 33 times, in 1-6s modulation time intervals. PMID:23506701

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

2013-02-27

212

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

Microsoft Academic Search

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

T. A. DeVol; R. A. Fjeld

1995-01-01

213

Influence of surface heating condition on local heat transfer in a rotating square channel with smooth walls and radial outward flow  

SciTech Connect

The effect of a surface heating condition on the local heat transfer coefficient in a rotating square channel with smooth walls and radial outward flow was investigated for Reynolds numbers from 2,500 to 25,000 and rotation numbers from 0 to 0.352. The square channel, composed of six isolated copper sections, has a length-to-hydraulic diameter ratio of 12. The mean rotating radius to the channel hydraulic diameter ratio is kept at a constant value of 30. Four surface heating conditions were tested: (1) four walls at uniform temperature, (2) temperature ratio of leading surface to side wall and trailing surface to side wall is 1.05 and 1.10, respectively, (3) trailing surface hot and remaining three walls cold, and (4) leading surface not and remaining three walls cold. The results show that the heat transfer coefficients on the leading surface are much lower than that of the trailing surface due to rotation. For case (1) of four walls at uniform temperature, the leading surface heat transfer coefficient decreases and then increases with increasing rotation numbers, and the trailing surface heat transfer coefficient increases monotonically with rotation numbers. However, the trailing surface heat transfer coefficients for cases (2) and (3) are slightly lower than case (1), and the leading surface heat transfer coefficients for cases (2) and (4) are significantly higher than for case (1). The results suggest that the local wall heating condition creates the local buoyancy forces, which reduce the effects of the bulk buoyancy and Coriolis forces. Therefore, the local heat transfer coefficients on the leading and trailing surfaces are altered by the surface local heating condition.

Han, J.C.; Zhang, Y.M. (Texas A M Univ., College Station, TX (United States). Dept. of Mechanical Engineering); Lee, C.P. (General Electric Co., Cincinnati, OH (United States))

1994-01-01

214

A Method of Correcting for Flow-Rate Fluctuations in Size Exclusion Chromatography Calculations: Applications to Methylene Chloride\\/Hexafluoroisopropanol Solvent System  

Microsoft Academic Search

The mixture of methylene chloride\\/hexafluoroisopropanol (70\\/30, v\\/v) is an excellent polyester solvent, but its low boiling point causes unstable flow when it is used for size exclusion chromatography (SEC). In high-performance SEC experiments, retention time is normally used to measure elution volume; however, unstable flow makes it difficult to calibrate an SEC column set or calculate molecular weight parameters from

Bruce L. Neff; J. R. Overton

1984-01-01

215

A Plant Kinetic Study of Alcoholic Fermentation Using Reversed-Flow Gas Chromatography  

Microsoft Academic Search

The reversed-flow gas chromatographic sampling technique is used to study the kinetics of alcoholic fermentation in a factory in conjunction with measurements of suspended particles in the fermenting medium. It was found that the overall process consists of four phases which have different first-order rate constants during ethanol formation. The second phase is the slowest, with its rate constant being

N. Economopoulos; N. Athanassopoulos; N. A. Katsanos; G. Karaiskakis; P. Agathonos; Ch. Vassilakos

1992-01-01

216

Optimal conductor selection for radial distribution systems  

Microsoft Academic Search

In this paper, an algorithm is proposed for selecting the optimum size of conductors of feeder sigments of radial distribution networks. The optimal size of conductor determined by load flow method is applied to the optimal distance radial distribution network. The conductor, which is determined by the proposed method, will maximize the total saving in cost of conducting material and

S Sivanagaraju; N Sreenivasulu; M Vijayakumar; T Ramana

2002-01-01

217

Distributed spot pricing in radial distribution systems  

Microsoft Academic Search

Spot pricing is a method for pricing electricity that maximizes the economic efficiency of the power system. The authors derive an expression for the spot prices in a radial distribution system, in terms of system quantities such as power line flows. The system's radial structure leads to simplified spot price expressions. They do not assume that all the problem data

L. Murphy; R. J. Kaye; F. F. Wu

1994-01-01

218

A free-flowing soap film combined with cavity ring-down spectroscopy as a detection system for liquid chromatography.  

PubMed

We have shown that a free-flowing soap film has sufficiently high-quality optical properties to allow it to be used in the cavity of a ring-down spectrometer (CRDS). The flow rates required to maintain a stable soap film were similar to those used in liquid chromatography and thus allowed interfacing with an HPLC system for use as an optical detector. We have investigated the properties of the system in a relevant analytical application. The soap film/CRDS combination was used at 355 nm as a detector for the separation of a mixture of nitroarenes. These compounds play a role in the residue analysis of areas contaminated with explosives and their decomposition products. In spite of the short absorption path length (9 microm) obtained by the soap film, the high-sensitivity of CRDS allowed a limit of detection of 4 x 10(-6) in absorption units (AU) or less than 17 fmol in the detection volume to be achieved. PMID:19913236

Vogelsang, Markus; Welsch, Thomas; Jones, Harold

2009-10-24

219

Electrokinetic chromatography in suppressed electroosmotic flow environment: use of a charged cyclodextrin for the separation of enantiomers and geometric isomers.  

PubMed

Electrokinetic chromatography (EKC), with negatively-charged cyclodextrins (NCDs) added to the buffer, was conducted in polyacrylamide-coated columns under suppression of electroosmotic flow. The equations of migration and resolution for neutral solutes in this mode of chromatography, which for brevity we term NCD-EKC, are presented. The chiral sulfated cyclodextrin, beta-CD-SBE (IV), used in this study is anionic over the entire pH range accessible to capillary electrophoresis, and the coated columns are stable and provide reproducible performance in the pH range 2.5-8.8. Optimum separation was obtained in the pH range where the solutes are neutral. The incorporation of an alkyl spacer between the sulfate ion and the rim of the cyclodextrin allows an unhindered approach and inclusion of neutral solutes in the cyclodextrin cavity. Solute migration time is inversely proportional to the concentration of the chiral selector. Separation (relative migration time difference) increases with decreasing chiral selector concentration and approaches a maximum, beyond which further decreases in chiral selector concentration result in broad peaks and loss of resolution. A chiral selector concentration of 1% in a 10 mM phosphate buffer produced excellent separation of amino acids and dipeptide enantiomers. In addition to being chiral selectors, cyclodextrins are also known as shape selectors. NCD-EKC is particularly suited for the separation of positional isomers of hydrophobic solutes. The separation of aflatoxin isomers and chlorophenol congeners is presented. In the separation of chlorophenols the more hydrophobic trichlorophenols eluted first and the least hydrophobic, phenol, eluted last. PMID:8957184

Janini, G M; Muschik, G M; Issaq, H J

1996-10-01

220

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

221

Flow-injection in-line complexation for ion-pair reversed phase high performance liquid chromatography of some metal-4-(2-pyridylazo) resorcinol chelates  

Microsoft Academic Search

Flow injection (FI) was coupled to ion-pair reversed phase high performance liquid chromatography (IP-RPHPLC) for the simultaneous analysis of some metal-4-(2-pyridylazo) resorcinol (PAR) chelates. A simple reverse flow injection (rFI) set-up was used for in-line complexation of metal-PAR chelates prior to their separation by IP-RPHPLC. The rFI conditions were: injection volume of PAR 85?L, flow rate of metal stream 4.5mLmin?1,

Supalax Srijaranai; Saiphon Chanpaka; Chutima Kukusamude; Kate Grudpan

2006-01-01

222

Ultra-low flow liquid chromatography assay with ultraviolet (UV) detection for piperine quantitation in human plasma.  

PubMed

A robust and sensitive ultra-low flow liquid chromatography (UFLC) method that can reproducibly, at reasonable cost, detect low concentrations of piperine from human plasma is necessary. Piperine in plasma was separated and quantified by a gradient method using ultraviolet detection at a maximal absorbance wavelength of 340 nm. An aliquot was injected onto a reversed-phase column Waters SymmetryShield, 2.1 x 100 mm, 3.5 microm, C(18) column, attached to a Waters absorbosphere, 4.6 x 30 mm, C(18) guard column and eluted with a mobile phase containing a mixture of acetonitrile/water/acetic acid (25:74.9:0.1, v/v/v) on line A and acetonitrile/acetic acid (99.9:0.1, v/v) on line B. The flow rate was 0.3 mL/min. The gradient method consisted of an opening condition of 20% pump B, with a linear increase to 37% pump B over 8 min, then a linear increase to 100% pump B at 11 min, 2 min at 100% pump B, and then a return to the opening condition (20% pump B) via a linear gradient over 2 min, followed by 5 min re-equilibration at opening conditions. The total run time was 20 min for each sample. All samples were processed protected from ambient light to avoid isomerization of piperine. The plasma assay was linear with R = 0.9995, with a lower limit of detection [signal-to-noise (S/N) > 5:1] of 100 pg of piperine loaded into the analytical system with acceptable accuracy and precision. Extraction recoveries of piperine from human plasma were 88% for quality control high (QCH), 93% for quality control medium (QCM), and 90% for quality control low (QCL), and the matrix effect was <12%. Piperine was quantifiable from a 50 mg oral dose given to human volunteers. A UFLC method for the rapid assay of human plasma with sensitivity to detect as low as 5 ng/mL piperine was developed. The method sensitivity equals that of liquid chromatography/tandem mass spectrometry (LC/MSMS) methods with much less cost. PMID:20465211

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

2010-06-01

223

A plant kinetic study of alcoholic fermentation using reversed-flow gas chromatography  

SciTech Connect

The reversed-flow gas chromatographic sampling technique is used to study the kinetics of alcoholic fermentation in a factory in conjunction with measurements of suspended particles in the fermenting medium. It was found that the overall process consists of four phases which have different first-order rate constants during ethanol formation. The second phase is the slowest with its rate constant being 4.3 and 13 times smaller than that of the first and third phases, respectively. There is also a decrease of suspended particles during the second phase. These results show that there is the possibility of increasing the rate constant during this phase, thereby increasing the overall production rate of ethanol significantly and thus lowering its cost of production.

Economopoulos, N.; Athanassopoulos, N. (B.G. Spiliopoulos Distilleri S.A., Patras (Greece)); Katsanos, N.A.; Karaiskakis, G.; Agathonos, P.; Vassilakos, Ch. (Univ. of Patras (Greece))

1992-12-01

224

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

225

Comparison of segmented flow analysis and ion chromatography for the quantitative characterization of carbohydrates in tobacco products.  

PubMed

Segmented flow analysis (SFA) and ion chromatography with pulsed amperometric detection (IC-PAD) are widely used analytical techniques for the analysis of glucose, fructose, and sucrose in tobacco. In the work presented here, 27 cured tobacco leaves and 21 tobacco products were analyzed for sugars using SFA and IC. The results of these analyses demonstrated that both techniques identified the same trends in sugar content across tobacco leaf and tobacco product types. However, comparison of results between techniques was limited by the selectivity of the SFA method, which relies on the specificity of the reaction of p-hydroxybenzoic acid hydrazide (PAHBAH) with glucose and fructose to generate a detectable derivative. Sugar amines and chlorogenic acid, which are found in tobacco, are also known to react with PAHBAH to form a reaction product that interferes with the analysis of fructose and glucose. To mitigate this problem, solid phase extraction (SPE) was used to remove interferences such as sugar amines and chlorogenic acid from sample matrices prior to SFA. A combination of C18 and cation exchange solid phase extraction cartridges was used, and the results from SFA and IC analyses showed significant convergence in the results of both analytical methods. For example, the average difference between the results from the SFA and IC analyses for flue-cured tobacco samples dropped by 73% when the two-step C18/cation exchange resin sample cleanup was used. PMID:23131129

Shifflett, John R; Jones, Lindsey A; Limowski, Edward R; Bezabeh, Dawit Z

2012-11-16

226

Evaluation of the forearm blood flow with C.W. Doppler in patients submitted to myocardial revascularization with the radial artery  

Microsoft Academic Search

Before harvesting the radial artery for coronary bypasses, investigating forearm vascularization to avoid postoperative ischemia of the hand is mandatory. The study involved 192 consecutive patients, 155 males and 37 females age 39–76 years (mean 56.1). The CW Doppler static and dynamic test was performed to evaluate the patency of the upper limb's arteries and the adequacy of the ulnar

Paolo Pola; Michele Serricchio; Roberto Flore; Paolo Tondi; Antonio Dal Lago; Antonio Gasbarring; Angelo Santoliquido; Demetrio De Martini; Laura Gerardino; Roberto Pola

1999-01-01

227

Flowmeter with radial vibrational mode for ultrasonic waves  

SciTech Connect

A method is described of operating an ultrasonic flowmeter for viscous fluids consisting of: transmitting and receiving ultrasonic acoustic waves generated by a piezoelectric crystal in upstream-downstream transducers of an ultrasonic flowmeter, the crystal having a radial vibrational mode; enhancing radial mode vibration while damping compressional mode vibration; and determining flow rate from the acoustic waves of radial vibrational mode.

Brown, A.E.

1986-07-22

228

Radial-capitellar implant  

US Patent & Trademark Office Database

A radial-capitellar implant for surgical replacement of the capitellum of the humerus and, optionally, the head of the radius. The radial-capitellar implant includes a capitellar implant or surface replacement arthroplasty of the capitellum and a radial prosthesis for replacement of the head of the radius. In one embodiment the radial prosthesis includes an articular head which moveable articulates with a stem implantable in the radius.

Cooney, III; William P. (Rochester, MN); Morrey; Bernard F. (Rochester, MN); Leibel; David A. (Princeton, MN)

2007-01-09

229

On-line coupling of flow injection displacement sorption preconcentration to high-performance liquid chromatography for speciation analysis of mercury in seafood  

Microsoft Academic Search

A simple and cost-effective method for speciation analysis of trace mercury in seafood was developed by on-line coupling flow injection microcolumn displacement sorption preconcentration to high-performance liquid chromatography (HPLC) with UV detection. The methodology involved the presorption of the Cu-PDC (pyrrolidine dithiocarbamate) chelate onto a microcolumn packed with a cigarette filter sorbent, simultaneous preconcentration of Hg(II), methylmercury (MeHg), ethylmercury (EtHg),

Li-Ming Dong; Xiu-Ping Yan; Yan Li; Yan Jiang; Shan-Wei Wang; Dong-Qing Jiang

2004-01-01

230

Assessment of neuroactive steroid formation in diabetic rat spinal cord using high-performance liquid chromatography and continuous flow scintillation detection  

Microsoft Academic Search

The combination of pulse-chase experiments with high-performance liquid chromatography and continuous flow scintillation detection was used successfully to determine the effects of chronic diabetes on neurosteroid production in the adult rat spinal cord. The long-term diabetes was induced by treatment of adult rats with streptozotocin. In the first part, the review provides an extensive description of the HPLC combined with

Ayikoe Guy Mensah-Nyagan; Simona Saredi; Veronique Schaeffer; Cherkaouia Kibaly; Laurence Meyer; Roberto Cosimo Melcangi; Christine Patte-Mensah

2008-01-01

231

Numerical method for the estimation of column radial heterogeneity and of the actual column efficiency from tailing peak profiles.  

PubMed

It is probably impossible to prepare high-performance liquid chromatography (HPLC) columns that have a completely homogeneous packing structure. Many reports in the literature show that the radial distributions of the mobile phase flow velocity and the local column efficiency are not flat, even in columns considered as good. A degree of radial heterogeneity seems to be a common property of all HPLC columns and an important source of peak tailing, which prevents the derivation of accurate information on chromatographic behavior from a straightforward analysis of elution peak profiles. This work reports on a numerical method developed to derive from recorded peak profiles the column efficiency at the column center, the degree of column radial heterogeneity, and the polynomial function that best represents the radial distributions of the flow velocity and the column efficiency. This numerical method was applied to two concrete examples of tailing peak profiles previously described. It was demonstrated that this numerical method is effective to estimate important parameters characterizing the radial heterogeneity of chromatographic columns. PMID:21138261

Miyabe, Kanji; Guiochon, Georges

2010-12-07

232

Voltage Stability Analysis of Radial Distribution Networks  

Microsoft Academic Search

The paper presents voltage stability analysis of radial distribution networks. A new stability index is proposed to identify the nodes that are on the verge of voltage collapse. The value of the proposed voltage stability index is calculated at each node of the network. A modified load flow method is used for voltage stability analysis. The modified load flow method

R. RANJAN; D. DAS

2003-01-01

233

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

234

Commission 30: Radial Velocities  

NASA Astrophysics Data System (ADS)

The past three-year period has seen steady efforts to collect large numbers of radial-velocity (RV) measurements, as well as important applications of radial velocities to astrophysics. Improvements in precision continue to be driven largely by exoplanet research. A workshop entitled ``Astronomy of Exoplanets with Precise Radial Velocities'' took place in August of 2010 at Penn State University (USA), and was attended by some 100 researchers from around the world. The meeting included thorough discussions of the current capabilities and future potential of the radial velocity technique, as well as data analysis algorithms to improve precision at visible and near-infrared wavelengths.

Torres, Guillermo; Pourbaix, Dimitri; Udry, Stephane; Marcy, Geoffrey W.; Mathieu, Robert D.; Mazeh, Tsevi; Minniti, Dante; Moutou, Claire; Pepe, Francesco; Turon, Catherine; Zwitter, Tomaz

2012-04-01

235

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

236

Radial distribution test feeders  

Microsoft Academic Search

Many computer programs are available for the analysis of radial distribution feeders. In 1992 a paper was published that presented the complete data for three four-wire wye and one three-wire delta radial distribution test feeders. The purpose of publishing the data was to make available a common set of data that could be used by program developers and users to

W. H. Kersting

2001-01-01

237

Methods and apparatus for radially compliant component mounting  

SciTech Connect

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

238

Triple acting radial seal  

SciTech Connect

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

239

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.

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

2011-01-01

240

Radial gate evaluation: Olympus Dam, Colorado  

SciTech Connect

The report presents a structural analysis of the radial gates of Olympus Dam in eastern Colorado. Five 20-foot wide by 17-foot high radial gates are used to control flow through the spillway at Olympus Dam. The spillway gates were designed in 1947. The gate arm assemblies consist of two separate wide flange beams, with a single brace between the arms. The arms pivot about a 4.0-inch diameter pin and bronze graphite-insert bushing. The pin is cantilevered from the pier anchor girder. The radial gates are supported by a pin bearing on a pier anchor birder bolted to the end of the concrete pier. The gates are operated by two-part wire rope 15,000-pound capacity hoise. Stoplog slots upstream of the radial gates are provided in the concrete piers. Selected drawings of the gates and hoists are located in appendix A.

NONE

1997-06-01

241

Fundamental equation of dual-mode gradient elution in liquid chromatography involving simultaneous changes in flow rate and mobile-phase composition.  

PubMed

The rigorous derivation of the fundamental equation of the dual-mode gradient elution in liquid chromatography involving any type of simultaneous changes in flow rate and mobile-phase composition is developed following Drake's approach. The equation is a generalization of the already known fundamental equations of single gradient when either the mobile-phase composition or the flow rate is constant. The theory was tested in the retention prediction from isocratic data of 18 o-phthalaldehyde derivatives of amino acids in eluting systems modified by acetonitrile or methanol. The retention prediction obtained for all solutes under all dual-mode gradient conditions was excellent. The average percentage error between experimental and predicted retention times ranged from 0.9 to 2.5%. Two approximations that simplify the calculations considerably without increasing the above error were also proposed. PMID:17444616

Pappa-Louisi, A; Nikitas, P; Balkatzopoulou, P; Louizis, G

2007-04-20

242

Optimisation and routine use of generic ultra-high flow-rate liquid chromatography with mass spectrometric detection for the direct on-line analysis of pharmaceuticals in plasma  

Microsoft Academic Search

The use of ultra-high flow-rate chromatography coupled to mass spectrometry offers great potential for the rapid, on-line analysis of pharmaceutical compounds in plasma as it permits high throughput direct analysis of plasma samples without any time-consuming sample preparation such as solid-phase extraction. The coupling of mass spectrometry with high-performance liquid chromatography often results in enhanced selectivity and sensitivity compared to,

J Ayrton; G. J Dear; W. J Leavens; D. N Mallett; R. S Plumb

1998-01-01

243

On the Neoclassical Relationship between the Radial Electric Field and Radial Current in Tokamak Plasmas  

NASA Astrophysics Data System (ADS)

The fluid equation is analytically derived in a rigorous manner, stipulating the relationship between the radial electric field and radial current in tokamak plasmas, especially when heated by neutral beam injection. On a very short time scale compared to the decay in poloidal rotation, the polarization current compensates for the non-ambipolar fast-ion radial current, producing a concomitant time change in the radial electric field. This polarization current predominates among the constituents of the radial current that produces the \\mbi{j}×\\mbi{B} torque. For times comparable to or longer than the decay time, the polarization current is no longer sufficient to compensate for the fast-ion radial current. In a steady state where the radial electric field is constant over time, the polarization current vanishes and the orthogonal conduction current becomes a sole component of the radial current that continues to flow as long as the charge separation occurs due to the neutral beam injection. Analytical work demonstrates that the basis equations of the one-dimensional transport code TASK/TX essentially have the capability to reproduce the phenomena derived, which is subsequently confirmed by numerical simulation.

Honda, Mitsuru; Fukuyama, Atsushi; Nakajima, Noriyoshi

2011-11-01

244

Pressure jumps due to flow interruptions as source of system peaks in liquid chromatography with mixed eluents  

Microsoft Academic Search

Summary  Brief pressure changes take often place within a liquid chromatography column, e.g., during sample injection. It is shown\\u000a that pressure jumps may cause local changes in the composition of a mixed effluent and the rise of system peaks in the chromatogram.\\u000a This is a consequence of the dependence of sorption equilibrium on pressure.

T. Macko; L. Šoltés; D. Berek

1989-01-01

245

Measurement of bromate in bread by high performance liquid chromatography with post?column flow reactor detection  

Microsoft Academic Search

An analytical procedure was developed to measure bromate residues in baked goods using a sequence of clean?up procedures followed by high performance liquid chromatography (HPLC) with a post?column reaction for oxidants. Deionized water was used to extract bromate from bread samples. The extract was treated with a C?18 solid phase extraction column to remove lipids, a cation exchange column with

Katsuichi Himata; Masaaki Noda; Susumu Ando; Yuji Yamada

1997-01-01

246

Measurement of bromate in bottled water by high?performance liquid chromatography with post?column flow reactor detection  

Microsoft Academic Search

The objective of this work was to develop a reliable, ragged high?performance liquid chromatographic (HPLC) method for determination of trace levels of bromate (< 10 ?g\\/l) in bottled water. HPLC separation was achieved by ion interaction chromatography using a C?18 reversed?phase column and a mobile phase consisting of methanol\\/water (20:80, v\\/v) with tetrabutylammonium acetate as the ion interaction reagent. A

Charles R. Warner; Daniel H. Daniels; Frank L. Joe Jr; Gregory W. Diachenko

1996-01-01

247

Numerical simulation of radial compressor stage  

NASA Astrophysics Data System (ADS)

Article describes numerical simulations of air flow in radial compressor stage in NUMECA CFD software. In simulations geometry variants with and without seals are used. During tasks evaluating was observed seals influence on flow field and performance parameters of compressor stage. Also is described CFDresults comparison with results from design software based on experimental measurements and monitoring of influence of seals construction on compressor stage efficiency.

Syka, T.; Lu?á?ek, O.

2013-04-01

248

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

249

A new physical model based on cascading column experiments to reproduce the radial flow and transport of micro-iron particles.  

PubMed

In the field of aquifer restoration and civil engineering, fluids and suspensions are delivered in porous media via well injection. The flow field resulting around the well is three-dimensional. Since two and three-dimensional experiments which can be used to reproduce such flow fields are, although accurate, extremely elaborate and time consuming, the authors suggest to substitute them by a cascade of interdependent, one-dimensional (column) experiments. The new method is used to simulate the injection in aquifers of micro-iron particles dispersed in a shear thinning gel of guar gum and allows the prediction of iron particle distribution around the well and of injection pressure. The method respects the mass balance at the field scale and its predictions are in good agreement with those of a mathematical model proposed in the literature. The method is consistent with the Triad Approach, a way to improve remediation efficiency proposed by the U.S. Environmental Protection Agency. The representativeness of the proposed tests combined with their simplicity and relative inexpensiveness make this new method applicable and useful in the planning and design of real remediation. PMID:22940707

Comba, Silvia; Braun, Jürgen

2012-08-03

250

Approximate theory for radial filtration/consolidation  

SciTech Connect

Approximate solutions are developed for filtration and subsequent consolidation of compactible cakes on a cylindrical filter element. Darcy`s flow equation is coupled with equations for equilibrium stress under the conditions of plane strain and axial symmetry for radial flow inwards. The solutions are based on power function forms involving the relationships of the solidosity {epsilon}{sub s} (volume fraction of solids) and the permeability K to the solids effective stress p{sub s}. The solutions allow determination of the various parameters in the power functions and the ratio k{sub 0} of the lateral to radial effective stress (earth stress ratio). Measurements were made of liquid and effective pressures, flow rates, and cake thickness versus time. Experimental data are presented for a series of tests in a radial filtration cell with a central filter element. Slurries prepared from two materials (Microwate, which is mainly SrSO{sub 4}, and kaolin) were used in the experiments. Transient deposition of filter cakes was followed by static (i.e., no flow) conditions in the cake. The no-flow condition was accomplished by introducing bentonite which produced a nearly impermeable layer with negligible flow. Measurement of the pressure at the cake surface and the transmitted pressure on the central element permitted calculation of k{sub 0}.

Tiller, F.M. [Univ. of Houston, TX (United States); Kirby, J.M. [Commonwealth Scientific and Industrial Research Organization, Canberra (Australia). Soils Div.; Nguyen, H.L. [Veteran`s Hospital, Los Angeles, CA (United States)

1996-10-01

251

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

2012-06-26

252

Nepem-211 ion exchange conductive membrane immobilized tris(2,2´-bipyridyl) ruthenium(II) electrogenerated chemiluminescence flow sensor for high-performance liquid chromatography and its application.  

PubMed

We developed a sensitive and robust electrogenerated chemiluminescence (ECL) flow sensor based on Ru(bpy)3(2+) immobilized with a Nepem-211 perfluorinated ion exchange conductance membrane, which has robustness and stability under a wide range of chemical and physical conditions, good electrical conductivity, isotropy and a high exchange capacity for immobilization of Ru(bpy)3(2+). The flow sensor has been used as a post-column detector in high-performance liquid chromatography for determination of erythromycin and clarithromycin in honey and pork, and tricyclic antidepressant drugs in human urine. Under optimal conditions, the linear ranges were 0.03-26 ng/?L and 0.01-1 ng/?L for macrolides and tricyclic antidepressant drugs, respectively. The detection limits were 0.02, 0.01, 0.01, 0.06 and 0.003 ng/?L for erythromycin, clarithromycin, doxepin, amitriptyline and clomipramine, respectively. There is no post-column reagent addition. In addition to the conservation expensive reagents, the experimental setup was simplified. The flow sensor was used for 2 years with high sensitivity and stability. PMID:23401164

Li, Yongbo; Zhang, Zhujun

2013-02-12

253

Radial segregation driven by axial migration  

NASA Astrophysics Data System (ADS)

The mixing of binary particles in a short rotating drum has been studied by performing discrete element simulations. The modeled granular materials were made of particles with same size and density but different color. We observed that the binary granular system inevitably went through a transient radial segregation state before reaching the final homogeneous mixing state. Depending on the filling degree and rotating speed, there exist totally three types of transient segregation patterns. Analysis of the flow field shows that such transient radial segregating phenomena were induced by different axial transporting characteristics of material.

Liu, Xiaoxing; Ge, Wei; Li, Jinghai

2013-06-01

254

Screening for multiple phosphodiesterase type 5 inhibitor drugs in dietary supplement materials by flow injection mass spectrometry and their quantification by liquid chromatography tandem mass spectrometry.  

PubMed

A flow injection tandem mass spectrometry method (FI-MS/MS) has been developed to detect enzyme phosphodiesterase type 5 inhibitors, including tadalafil, sildenafil, and vardenafil. Multiple reaction monitoring (MRM) was used to detect the drugs and product ion ratios were used for identification. FI-MS/MS was used for semi-quantification and liquid chromatography tandem mass spectrometry (LC-MS/MS) was used for further confirmation and quantification. One of 13 samples has been found to be adulterated with prescription levels of tadalafil and also low level of sildenafil. The method can be used for screening large numbers of herbal products for adulteration since it takes less than 1 min without chromatographic separation on a column. PMID:22695818

Song, Fenhong; El-Demerdash, Aref; Lee, Shwn-Ji Susie H

2012-05-23

255

Radial transfer effects for poloidal rotation  

NASA Astrophysics Data System (ADS)

Radial transfer of energy or momentum is the principal agent responsible for radial structures of Geodesic Acoustic Modes (GAMs) or stationary Zonal Flows (ZF) generated by the turbulence. For the GAM, following a physical approach, it is possible to find useful expressions for the individual components of the Poynting flux or radial group velocity allowing predictions where a mathematical full analysis is unfeasible. Striking differences between up-down symmetric flux surfaces and asymmetric ones have been found. For divertor geometries, e.g., the direction of the propagation depends on the sign of the ion grad-B drift with respect to the X-point, reminiscent of a sensitive determinant of the H-mode threshold. In nonlocal turbulence computations it becomes obvious that the linear energy transfer terms can be completely overwhelmed by the action of the turbulence. In contrast, stationary ZFs are governed by the turbulent radial transfer of momentum. For sufficiently large systems, the Reynolds stress becomes a deterministic functional of the flows, which can be empirically determined from the stress response in computational turbulence studies. The functional allows predictions even on flow/turbulence states not readily obtainable from small amplitude noise, such as certain transport bifurcations or meta-stable states.

Hallatschek, Klaus

2010-11-01

256

Active flow management in preparative chromatographic separations: a preliminary investigation into enhanced separation using a curtain flow inlet fitting and segmented flow outlet fitting.  

PubMed

Active flow management in the form of curtain flow sample introduction and segmented outlet flow control has been shown to enable sample to elute through a chromatography column under the principles of the "infinite diameter column". Such an elution process avoids the detrimental effects of the heterogeneity of particle-packed chromatographic columns by injecting the sample directly into the radial core region of the column, thus avoiding wall effects. The process described herein illustrates how the principles of the infinite diameter column can be applied using conventional injection devices suitable for long-term analysis that requires robust protocols. Using this approach, sensitivity in separation was 2.5 times greater than conventional chromatography, yielding a product at twice the concentration. Benefits of curtain flow injection are thus relevant to both preparative-scale and analytical-scale separations. PMID:22228597

Camenzuli, Michelle; Ritchie, Harald J; Ladine, James R; Shalliker, R Andrew

2012-01-09

257

Applying radial basis functions  

Microsoft Academic Search

Discusses the application of neural networks to general and radial basis functions and in particular to adaptive equalization and interference rejection problems. Neural-network-based algorithms strike a good balance between performance and complexity in adaptive equalization, and show promise in spread spectrum systems

BERNARD MULGREW

1996-01-01

258

Radial basis functions  

Microsoft Academic Search

Radial basis function methods are modern ways to approximate multivariate functions, especially in the absence of grid data. They have been known, tested and analysed for several years now and many positive properties have been identied. This paper gives a selective but up-to-date survey of several recent developments that explains their usefulness from the theoretical point of view and contributes

M. D. Buhmann

2000-01-01

259

Parallel segmented flow chromatography columns: conventional analytical scale column formats presenting as a 'virtual' narrow bore column.  

PubMed

Narrow bore columns find advantage in HPLC applications when volumetric flow is important, For example, for detection processes that are volume limited. Yet there are significant drawbacks to narrow bore columns. Due to their small column volume relative to analytical scale columns, narrow bore columns are more affected by system dead volume. In addition the wall effect and the variation in packing density from the centre to the wall are more significant in these columns relative to larger scale analytical columns. In this study we operate a 4.6mm i.d. parallel segmented flow column in such a manner that it emulates 2.1mm i.d. and 3.0mm i.d. columns. By using a parallel segmented flow column in this way, it was possible to combine the benefits of narrow bore and analytical scale columns. PMID:22999201

Shalliker, R A; Camenzuli, M; Pereira, L; Ritchie, H J

2012-09-07

260

Effect of pitch-controlled guide vanes on the performance of a radial turbine for wave energy conversion  

Microsoft Academic Search

In order to develop a high performance radial turbine for wave energy conversion, a radial turbine with pitch-controlled guide vanes has been proposed and investigated experimentally by model testing. As a result, the performances of the presented radial turbine have been clarified under steady and unsteady flow conditions. Furthermore, it seems that the presented radial turbine is superior to a

Manabu Takao; Yoshihiro Fujioka; Toshiaki Setoguchi

2005-01-01

261

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

262

Resolving blended radial velocities  

NASA Astrophysics Data System (ADS)

In space, photometric surveys are very efficient to detect small transiting planets or stars which are contaminated by blended eclipsing binaries. We present some simulations compared to radial velocity (RV) observations obtained with the SOPHIE spectrograph (OHP, France) in order to determine the true nature of a brown dwarf candidate revealed by CoRoT: a background eclipsing binary diluted by a foreground star.

Santerne, Alexandre; Moutou, Claire; Bouchy, François

2011-11-01

263

A radial mode ultrasonic horn for the inactivation of Escherichia coli K12  

Microsoft Academic Search

Tuned cylindrical radial mode ultrasonic horns offer advantages over ultrasonic probes in the design of flow-through devices for bacterial inactivation. This study presents a comparison of the effectiveness of a radial horn and probe in the inactivation of Escherichia coli K12. The radial horn is designed using finite element analysis and the predicted modal parameters are validated using experimental modal

G. Hunter; M. Lucas; I. Watson; R. Parton

2008-01-01

264

The radial-velocity revolution  

SciTech Connect

Instruments and techniques designed for registering the minute Doppler shifts arising from stellar radial velocity are examined. Particular attention is given to the photographic spectrographs, the high-dispersion spectrographs ('digital speedometers'), and the Palomar spectrometer. The principle of using radial-velocity masks is described, and the use of interferometers for radial-velocity measurements is discussed. Results are presented of radial velocity observations for HD 114762, HD 210647, and Epsilon Tauri, together with interpretations of these results.

Griffin, R. (Cambridge Univ., Observatories (England))

1989-09-01

265

Management of an iatrogenic radial artery perforation: a case report.  

PubMed

A 73-year-old female patient underwent transradial coronary angiography with stable angina and signs of significant myocardial ischemia revealed by exercise stress test. After insertion of a 6F radial sheath into the right radial artery and intra-arterial administration of heparin plus verapamil, the hydrophilic guidewire could not be advanced under fluoroscopic guidance. Immediately afterwards, radial angiography was performed, which displayed a radial artery perforation with significant contrast extravasation. The perforated segment was crossed meticulously with the same guidewire after additional vasodilator drug administration. Afterwards, a 5F TIG catheter was advanced to the axillary artery and held in place for 20 minutes with application of external compression with a sphygmomanometer cuff at the level of systolic blood pressure. The same maneuver was again performed following cuff deflation and completion of coronary angiography with the 5F catheter. Final angiography displayed complete sealing of the perforation without a need for neutralization of heparin. External compression was continued for two hours, and after documentation of normal triphasic radial artery flow by Doppler ultrasound (DUS), the radial sheath was removed. The patient was discharged the following day with no evidence of hand ischemia and well-palpable radial artery pulse. DUS demonstrated normal radial artery flow one month later. This unusual complication was managed successfully with a simple and easily applicable technique that can be performed in such cases. PMID:23760121

Buturak, Ali; Demirci, Yasemin; Da?delen, Sinan

2013-06-01

266

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.

Osterday, Robert M.; Brodman, Richard F.

2013-01-01

267

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

268

Radial tunnel syndrome.  

PubMed

Radial tunnel syndrome is a pain syndrome resulting from compression of the posterior interosseous nerve at the proximal forearm. It has no specific radiologic or electrodiagnostic findings. Treatment should be started conservatively; if not successful, surgical treatment is indicated. The posterior interosseous nerve may be explored through dorsal or anterior approaches. All the potential sites of entrapment should be released, including complete release of the superficial head of the supinator muscle. Surgical treatment is generally successful, but patients who have associated lateral epicondylitis or those who are involved in workers' compensation claims have less successful outcomes. PMID:23026469

Naam, Nash H; Nemani, Sajjan

2012-10-01

269

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

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

270

Conversion of propan-2-ol on zeolites LaNaY and HY investigated by gas chromatography and in situ MAS NMR spectroscopy under continuous-flow conditions  

SciTech Connect

The conversion of propan-2-ol on zeolites HY and LaNaY has been investigated by gas chromatography (GC) and in situ {sup 1}H and {sup 13}C MAS NMR spectroscopy under continuous-flow conditions using a new MAS NMR microreactor with cylindrical catalyst bed. At reaction temperatures of T = 373 K and T = 393 K a propan-2-ol conversion of 50 and 100%, respectively, and the formation of propene, diisopropyl. ether, and small amounts of acetone was determined by GC. Applying in situ {sup 1}H and {sup 13}C MAS NMR spectroscopy, the initial step of the reaction was found to be the physisorption of propan-2-ol on Bronsted acid sites. A formation of isopropoxy species could be excluded by {sup 13}C MAS NMR spectroscopy. {sup 1}H MAS NMR spectroscopy indicated that the Bronsted acid sites of the zeolites LaNaY and HY were hydrated by water molecules in the first part of the induction period. These water molecules were formed in result of the propan-2-ol dehydration. The strong low-field shift of the {sup 1}H MAS NMR signals of the hydrated Bronsted acid sites is due to a partial protonation of adsorbed water molecules. At T = 393 K, a significant {sup 13}C MAS NMR signal of strongly bonded acetone molecules appeared at 220 ppm in the spectra of zeolites LaNaY and HY. As demonstrated by propan-2-ol conversion on a partially dealuminated zeolite HY, this by-reaction is promoted by extra-framework aluminium species. The formation of coke precursors which caused {sup 13}C MAS NMR signals at 10-50 ppm is explained by an oligomerization of propene. In situ {sup 13}C MAS NMR experiments carried out under a continuous flow of propene showed that the above-mentioned coke precursors are also formed on partially rehydrated zeolite HY. 25 refs., 14 figs., 1 tab.

Hunger, M.; Horvath, T. [Univ of Stuttgart (Germany)

1997-04-01

271

High-precision D/H measurement from organic mixtures by gas chromatography continuous-flow isotope ratio mass spectrometry using a palladium filter.  

PubMed

Continuous-flow high-precision determination of D/H ratios from an organic mixture is described using gas chromatography coupled to a Pd filter system as an interface for isotope ratio mass spectrometry. A gas chromatograph and combustion and reduction furnaces are connected to a Pd filter via a postcolumn head pressure makeup gas to increase chromatographic sensitivity. This interface is evaluated using benzene as an internal standard in a mixture of ethylbenzene and cyclohexanone in hexane with analyte quantities of < 3 ng (< 300 pg of H). A calibration curve is constructed using four benzene samples over a range of -48 to 372/1000 (delta DSMOW), resulting in an average benzene D/H precision of SD < 5/1000 (delta DSMOW) and deviations of < 4/1000 from the calibration curve. Ethylbenzene and cyclohexanone of a single D enrichment are analyzed as unknowns in three sample mixtures with varying D-enriched benzene and result in precisions of SD < 5/1000. No apparent memory is observed between peaks of differently enriched analytes within the same chromatogram. All results are corrected for ion source nonlinearities characteristic of hydrogen analysis, using the internal peakwise correction algorithm, described previously. A small dependence of isotope ratio on palladium membrane temperature is demonstrated over a range of 4 degrees C; therefore, with tighter control of palladium temperature, precision can probably be improved. The data indicate that this system is useful for rapid continuous-flow IRMS analysis of D/H ratios from organics in complex mixtures characteristic of geological and biological samples. PMID:8794931

Tobias, H J; Brenna, J T

1996-09-01

272

Speciation of metal-EDTA complexes by flow injection analysis with electrospray ionization mass spectrometry and ion chromatography with inductively coupled plasma mass spectrometry.  

PubMed

Flow injection analysis (FIA) with ESI-MS and ion chromatography (IC) with inductively coupled plasma-MS (ICP-MS) as the complementary technique have been explored for the determination of metal ions as their metal-EDTA complexes. ESI-MS enabled the identification of metal-EDTA complexes such as [Mn(EDTA)](2-), [Co(EDTA)](2-), [Ni(EDTA)](2-), [Cu(EDTA)](2-), [Zn(EDTA)](2-), [Pb(EDTA)](2-), and [Fe(EDTA)](1-) and their MS spectral showed that these metal-EDTA complexes were present in solution. Based on the ESI-MS, ion chromatographic separation and ICP-MS detection of these complexes are possible because IC-ICP-MS requires stable metal-EDTA complex during the chromatographic separation. The separation of these metal-EDTA complexes was achieved on an anion-exchange column with a mobile phase containing 30 mM NH(4)(HPO(4))(2) at pH 7.5 within 7 min with ICP-MS providing element specific detection. The ICP-MS LODs for the metal-EDTA were in the range of 0.1-0.5 microg/L with the exception of Fe (15 microg/L). The proposed method was a simple procedure for sample processing, using direct injection of sample without removal of sample matrix and was successfully applied to the determination of metal-EDTA complexes in real samples. PMID:18925619

Chen, ZuLiang; Sun, Qian; Xi, YunFei; Owens, Gary

2008-12-01

273

Affinity Chromatography.  

ERIC Educational Resources Information Center

|Presents selected recent advances in immobilization chemistry which have important connections to affinity chromatography. Discusses ligand immobilization and support modification. Cites 51 references. (CS)|

Gray, Gary R.

1980-01-01

274

Trace determination of herbicides in estuarine waters by liquid chromatography-high-flow pneumatically assisted electrospray mass spectrometry.  

PubMed

High-flow pneumatically assisted electrospray (ESP) was applied to the characterization of triazine (atrazine, simazine, ametryne, cyanazine, deethylatrazine and deisopropylatrazine), phenylurea (chlortoluron++, isoproturon, diuron, linuron and diflubenzuron) and other priority herbicides (alachlor, metolachlor). In LC-ESP-MS the [M+Na]+ ion was used as the base peak in most cases, with the exception of chlorotriazines, which showed [M+H]+ as the base peak. When LC-TSP-MS was used, [M+H]+ was the base peak for many of the pesticides, with the exception of linuron and diflubenzuron, which showed [M+NH4]+ as the base peak. The ESP results were compared with those obtained with thermospray (TSP). LC-TSP-MS offered greater sensitivity for triazines than phenylurea herbicides, whereas the use of LC-ESP-MS offered an enhancement in sensitivity for phenylurea herbicides. As regards the fragmentation obtained using both techniques, ESP offered a considerable amount of structural information for the different chlorotriazines studied when the extraction voltage was increased from 20 to 40 V. Liquid-liquid extraction with dichloromethane was used for the trace enrichment of the different herbicides in estaurine water samples from the Elorn river (France). The presence of the different triazine metabolites, atrazine, simazine, metolachlor, isoproturon and diuron was confirmed by both LC-MS techniques. PMID:8556145

Molina, C; Durand, G; Barceló, D

1995-09-29

275

Radial head fractures: indications and outcomes for radial head arthroplasty.  

PubMed

Radial head fractures without associated bony or ligamentous injury can be safely treated with internal fixation, if possible, or arthroplasty if nonreconstructable. However, nonreconstructable radial head fractures in association with elbow dislocation and/or ligamentous injury in the elbow or forearm represent a specific subset of injuries that requires restoration of the radiocapitellar articulation for optimal function. The purpose of this article was to summarize the indications for radial head arthroplasty and discuss the reported outcomes. PMID:23827844

Fowler, John R; Goitz, Robert J

2013-04-17

276

Harmonic source and type identification in a radial distribution system  

Microsoft Academic Search

To aid in locating the source and type of harmonics in a distribution system, a computer program called HARM TRACER has been developed. HARM TRACER is a reverse harmonic power flow study program which traces the flow of harmonics in a radial distribution system from the point of measurement to the harmonic source or sources. It does so by considering

Asrat Teshome

1991-01-01

277

Systematic optimisation and evaluation of on-line, off-line and stop-flow comprehensive hydrophilic interaction chromatography×reversed phase liquid chromatographic analysis of procyanidins, part I: theoretical considerations.  

PubMed

Comprehensive two-dimensional liquid chromatography (LC×LC) provides significantly improved separation for complex real-life samples. LC×LC can be performed in one of three different ways, using on-line, off-line, or stop-flow configurations. We have previously shown how off-line comprehensive hydrophilic interaction chromatography (HILIC)×reversed-phase liquid chromatography (RP-LC) provides a powerful separation system for procyanidins (PCs), one of the most complex fractions of natural phenolics. In the current contribution, a systematic approach for the optimisation and evaluation of each of the LC×LC methodologies is presented using HILIC×RP-LC analysis of PCs as application. Optimisation was performed using the peak capacities of individual one-dimensional separations measured for different gradient times and flow rates and their combination in each of the three LC×LC modes by taking into account the effects of first dimension under-sampling, the degree of orthogonality between the two dimensions and additional band broadening associated with stop-flow analysis. The performance of all three methods is compared in terms of practical peak capacities, analysis times and peak production rates. One-dimensional LC provided the best performance for separations requiring relatively low peak capacities, whereas the on-line LC×LC system was advantageous for required practical peak capacities up to ~600. For higher resolution, the off-line or stop-flow systems should be used. Especially noteworthy is the fact that, due to slow diffusion of PCs, the contribution of stop-flow to first dimension band broadening was negligible for stop-flow times of up to 15min. In a separate contribution, the experimental verification of the findings of this study will be reported. PMID:23561732

Kalili, Kathithileni M; de Villiers, André

2013-03-17

278

Cyclic and radial variation of the Doppler power from porcine whole blood  

Microsoft Academic Search

The Doppler power from porcine blood was observed in a mock flow loop to have cyclic and radial variation during a pulsatile cycle. It was found to decrease with shear rate under steady flow, except near the center of the tube at which other mechanisms such as the effects of radial distribution on the rouleaux might be involved. Under pulsatile

Dong-Guk Paeng; K. Kirk Shung

2003-01-01

279

Radial electric field and transport near the rational surface and the magnetic island in LHD  

Microsoft Academic Search

The structure of the radial electric field and heat transport at the magnetic island in the large helical device (LHD) are investigated by measuring the radial profile of the poloidal flow with charge exchange spectroscopy and measuring the time evolution of the electron temperature with ECE. A vortex-like plasma flow along the magnetic flux surface inside the magnetic island is

K. Ida; S. Inagaki; N. Tamura; T. Morisaki; N. Ohyabu; K. Khlopenkov; S. Sudo; K. Watanabe; M. Yokoyama; T. Shimozuma; Y. Takeiri; K. Itoh; M. Yoshinuma; Y. Liang; K. Narihara; K. Tanaka; Y. Nagayama; T. Tokuzawa; K. Kawahata; H. Suzuki; A. Komori; T. Akiyama; N. Ashikawa; M. Emoto; H. Funaba; P. Goncharov; M. Goto; H. Idei; K. Ikeda; M. Isobe; O. Kaneko; H. Kawazome; T. Kobuchi; A. Kostrioukov; S. Kubo; R. Kumazawa; S. Masuzaki; T. Minami; J. Miyazawa; S. Morita; S. Murakami; S. Muto; T. Mutoh; Y. Nakamura; H. Nakanishi; Y. Narushima; K. Nishimura; N. Noda; T. Notake; H. Nozato; S. Ohdachi; Y. Oka; M. Osakabe; T. Ozaki; B. J. Peterson; A. Sagara; T. Saida; K. Saito; S. Sakakibara; R. Sakamoto; M. Sasao; K. Sato; M. Sato; T. Seki; M. Shoji; N. Takeuchi; K. Toi; Y. Torii; K. Tsumori; T. Watari; Y. Xu; H. Yamada; I. Yamada; S. Yamamoto; T. Yamamoto; Y. Yoshimura; I. Ohtake; K. Ohkubo; T. Mito; T. Satow; T. Uda; K. Yamazaki; K. Matsuoka; O. Motojima; M. Fujiwara

2004-01-01

280

A Twist on Packing Columns for Reversed Phase Liquid Chromatography  

Microsoft Academic Search

Liquid chromatography is one of the most widely used analytical techniques for the separation of complex mixtures. Great advances have been made in the last twenty years in column technology, i.e. stationary phases, but few advances have been made in column packing technology. In this study, two new methods for packing analytical reversed-phase liquid chromatography (RPLC) columns are introduced: radially

J. Paul McCall

2004-01-01

281

An automated method for measurement of methoxetamine in human plasma by use of turbulent flow on-line extraction coupled with liquid chromatography and mass spectrometric detection.  

PubMed

Methoxetamine is a new ketamine derivative designer drug which has recently become available via the Internet marketed as "legal ketamine". It is a new dissociative recreational drug, acting as an NMDA receptor antagonist and dopamine reuptake inhibitor. The objective of this study was to develop on-line automated sample preparation using a TurboFlow device coupled with liquid chromatography with ion-trap mass spectrometric detection for measurement of methoxetamine in human plasma. Samples (100 ?L) were vortex mixed with internal standard solution (ketamine-d4 in acetonitrile). After centrifugation, 20 ?L of the supernatant was injected on to a 50 mm × 0.5-mm C18XL Turboflow column. The retained analytes were then back-flushed on to a 50 mm × 3-mm (3 ?m) Hypersil Gold analytical column for chromatographic separation, then eluted with a formate buffer-acetonitrile gradient. Methoxetamine and the IS were ionized by electrospray in positive mode. Parent [M + H](+) ions were m/z 248.1 for methoxetamine and m/z 242.0 for the IS. The most intense product ions from methoxetamine (m/z 203.0) and the IS (m/z 224.0) were used for quantification. The assay was accurate (96.8-108.8% range) and precise (intra and inter-day coefficients of variation <8.8%) over the range of 2.0 (lower limit of quantification) to 1000.0 ng mL(-1) (upper limit of quantification). No matrix effect was observed. This method has been successfully applied to determination of plasma concentrations of methoxetamine in the first French hospitalization case report after acute intoxication; the plasma concentration was 136 ng mL(-1). PMID:23079952

Abe, Emuri; Ricard, Florian; Darrouzain, François; Alvarez, Jean Claude

2012-10-19

282

An improved flow analysis-ion chromatography method for determination of cationic and anionic species at trace levels in Antarctic ice cores.  

PubMed

A method was developed for the quantitative determination of cations and anions in Antarctic ice cores at microgL(-1) and sub-microgL(-1) levels by ion chromatography (IC), after ultra-clean decontamination procedures. Strict manipulation and decontamination procedures were used in sub-sampling, in order to minimise sample contamination. Na+, NH4+, K+, Mg2+ and Ca2+ were determined by 12-min isocratic elution (H2SO4 eluent). Contemporaneously, in a parallel device, F-, MSA (methanesulfonic acid), Cl-, NO3- and SO4(2-) were analysed in a single 12-min run with multiple-step elution using Na2CO3/NaHCO3 as eluent. Melted ice samples were pumped from their still-closed containers (polystyrene accuvettes with polyethylene caps), shared between the two ion chromatographic systems, online filtered (0.45 microm Teflon membrane) and pre-concentrated (anions and cations pre-concentration columns) using a flow analysis system, thus avoiding uptake of contaminants from the laboratory atmosphere. Sensitivity, linear range, reproducibility and detection limit were evaluated for each chemical species. Anion or cation detection limits ranged from 0.01 to 0.15 microgL(-1) by using a relatively small sample volume (1.5 mL). Such values are significantly lower than those reported in literature for almost all the components. These methods were successfully applied to the analysis of cations and anions at trace levels in the Dome C ice core. The composition of the atmospheric aerosol for the last 850 kyr was reconstructed by high-resolution continuous chemical stratigraphies. Concentration trends in the last nine glacial-interglacial climatic cycles were shown and briefly discussed. PMID:17963839

Morganti, Andrea; Becagli, Silvia; Castellano, Emiliano; Severi, Mirko; Traversi, Rita; Udisti, Roberto

2007-09-29

283

Scale and variance of radial liquid maldistribution in trickle beds  

Microsoft Academic Search

Radial distribution of liquid flow rate in a trickle bed with an inner diameter of 0.283m was measured for various bed heights under varying flow conditions. The total variance of flow distribution was partitioned into large-scale and small-scale components, and the statistical method was used to analyze the experimental data and determine the scale of liquid maldistribution. The scale of

Yue-Fa Wang; Zai-Sha Mao; Jiayong Chen

1998-01-01

284

Radial systems of dark globules  

SciTech Connect

The author gives examples of radial systems consisting of dark globules and ''elephant trunks''. Besides already known systems, which contain hot stars at their center, data are given on three radial systems of a new kind, at the center of which there are stars of spectral types later than B. Data are given on 32 globules of radial systems of the association Cep OB2. On the basis of the observational data, it is concluded that at least some of the isolated Bok globules derive from elephant trunks and dark globules forming radial systems around hot stars. It is also suggested that the two molecular clouds situated near the Rosette nebula and possessing velocities differing by ca 20 km/sec from the velocity of the nebula could have been ejected in opposite directions from the center of the nebula. One of these clouds consists of dark globules forming the radial system of the Rosette nebula.

Gyul'budagyn, A.L.

1986-03-01

285

Affinity Chromatography  

NSDL National Science Digital Library

Using exposition, graphics, and commercial videos, this module teaches the theory and application of affinity chromatography in the characterization of proteins, nucleic acids, and other biochemical/biomedical systems. Problems and application examples support the tutorial material.

2011-05-25

286

Gas Chromatography  

NSDL National Science Digital Library

This is a website from the US Environmental Protection Agency that explains Gas Chromatography for those interested in environmental analysis. The level of the material assumes some user background in the field.

2011-05-19

287

Design and performance of a new continuous-flow sample-introduction system for flame infrared-emission spectrometry: Applications in process analysis, flow injection analysis, and ion-exchange high-performance liquid chromatography.  

PubMed

A new sample introduction system for the analysis of continuously flowing liquid streams by flame infrared-emission (FIRE) spectrometry has been developed. The system uses a specially designed purge cell to strip dissolved CO(2) from solution into a hydrogen gas stream that serves as the fuel for a hydrogen/air flame. Vibrationally excited CO(2) molecules present in the flame are monitored with a simple infrared filter (4.4 mum) photometer. The new system can be used to introduce analytes as a continuous liquid stream (process analysis mode) or on a discrete basis by sample injection (flow injection analysis mode). The key to the success of the method is the new purge-cell design. The small internal volume of the cell minimizes problems associated with purge-cell clean-out and produces sharp, reproducible signals. Spent analytical solution is continuously drained from the cell, making cell disconnection and cleaning between samples unnecessary. Under the conditions employed in this study, samples could be analyzed at a maximum rate of approximately 60/h. The new sample introduction system was successfully tested in both a process analysis- and a flow injection analysis mode for the determination of total inorganic carbon in Waco tap water. For the first time, flame infrared-emission spectrometry was successfully extended to non-volatile organic compounds by using chemical pretreatment with peroxydisulfate in the presence of silver ion to convert the analytes into dissolved carbon dioxide, prior to purging and detection by the FIRE radiometer. A test of the peroxydisulfate/Ag(+) reaction using six organic acids and five sugars indicated that all 11 compounds were oxidized to nearly the same extent. Finally, the new sample introduction system was used in conjunction with a simple filter FIRE radiometer as a detection system in ion-exchange high-performance liquid chromatography. Ion-exchange chromatograms are shown for two aqueous mixtures, one containing six organic acids and the second containing six mono-, di-, and trisaccharides. PMID:18965720

Lam, C K; Zhang, Y; Busch, M A; Busch, K W

1993-06-01

288

High-Performance Liquid Chromatography  

NASA Astrophysics Data System (ADS)

High-performance liquid chromatography (HPLC) developed during the 1960s as a direct offshoot of classic column liquid chromatography through improvements in the technology of columns and instrumental components (pumps, injection valves, and detectors). Originally, HPLC was the acronym for high-pressure liquid chromatography, reflecting the high operating pressures generated by early columns. By the late 1970s, however, high-performance liquid chromatography had become the preferred term, emphasizing the effective separations achieved. In fact, newer columns and packing materials offer high performance at moderate pressure (although still high pressure relative to gravity-flow liquid chromatography). HPLC can be applied to the analysis of any compound with solubility in a liquid that can be used as the mobile phase. Although most frequently employed as an analytical technique, HPLC also may be used in the preparative mode.

Reuhs, Bradley L.; Rounds, Mary Ann

289

Statistical theory of chromatography: new outlooks for affinity chromatography.  

PubMed Central

We have developed further the statistical approach to chromatography initiated by Giddings and Eyring, and applied it to affinity chromatography. By means of a convenient expression of moments the convergence towards the Laplace-Gauss distribution has been established. The Gaussian character is not preserved if other causes of dispersion are taken into account, but expressions of moments can be obtained in a generalized form. A simple procedure is deduced for expressing the fundamental constants of the model in terms of purely experimental quantities. Thus, affinity chromatography can be used to determine rate constants of association and dissociation in a range considered as the domain of the stopped-flow methods.

Denizot, F C; Delaage, M A

1975-01-01

290

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

291

Dedicated radial ventriculography pigtail catheter.  

PubMed

A new dedicated cardiac ventriculography catheter was specifically designed for radial and upper arm arterial access approach. Two catheter configurations have been developed to facilitate retrograde crossing of the aortic valve and to conform to various subclavian, ascending aortic and left ventricular anatomies. The "short" dedicated radial ventriculography catheter is suited for horizontal ascending aortas, obese body habitus, short stature and small ventricular cavities. The "long" dedicated radial ventriculography catheter is suited for vertical ascending aortas, thin body habitus, tall stature and larger ventricular cavities. This new design allows for improved performance, faster and simpler insertion in the left ventricle which can reduce procedure time, radiation exposure and propensity for radial artery spasm due to excessive catheter manipulation. Two different catheter configurations allow for optimal catheter selection in a broad range of patient anatomies. The catheter is exceptionally stable during contrast power injection and provides equivalent cavity opacification to traditional femoral ventriculography catheter designs. PMID:23773499

Vidovich, Mladen I

292

Coplanar Waveguide Radial Line Stub.  

National Technical Information Service (NTIS)

A coplanar waveguide radial line stub resonator is experimentally characterized with respect to stub radius, sectoral angle, substrate thickness, and relative dielectric constant. A simple closed-form design equation which predicts the resonance radius of...

R. N. Simons S. R. Taub

1993-01-01

293

Optimal sizing of capacitors placed on a radial distribution system  

Microsoft Academic Search

The capacitor sizing problem is a special case of the general capacitor placement problem. The problem is to determine the optimal size of capacitors placed on the nodes of a radial distribution system so that the real power losses will be minimized for a given load profile. This problem is formulated as a nonlinear programming problem. The ac power flow

M. E. Baran; F. F. Wu

1989-01-01

294

A novel technique for the analysis of radial distribution systems  

Microsoft Academic Search

This paper presents a novel technique to obtain the solution of load flow in radially operated distribution networks, in which the loads can be represented by any model. This method is simple, easy to program and is based on the formation of a constant sparse upper triangular matrix, which is used to determine the bus voltages. Test results of IEEE

P. Aravindhababu; S. Ganapathy; K. R. Nayar

2001-01-01

295

Soil water retention curve analysis using radial basis function network  

Microsoft Academic Search

The soil water retention curve (SWRC) shows the relationship between soil suction pressure and water content, which is one of the key hydraulic properties to study the flow and solute transports in unsaturated zone. A radial basis function network (RBFN) was developed to describe the SWRC with the observed soil suction pressure and simultaneous soil water content derived from laboratory

Jin Gao; Yanfeng Liu

2010-01-01

296

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

297

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

298

Green chromatography.  

PubMed

Analysis of organic compounds in samples characterized by different composition of the matrix is very important in many areas. A vast majority of organic compound determinations are performed using gas or liquid chromatographic methods. It is thus very important that these methods have negligible environmental impact. Chromatographic techniques have the potential to be greener at all steps of the analysis, from sample collection and preparation to separation and final determination. The paper summarizes the approaches used to accomplish the goals of green chromatography. While complete elimination of sample preparation would be an ideal approach, it is not always practical. Solventless extraction techniques offer a very good alternative. Where solvents must be used, the focus should be on the minimization of their consumption. The approaches used to make chromatographic separations greener differ depending on the type of chromatography. In gas chromatography it is advisable to move away from using helium as the carrier gas because it is a non-renewable resource. GC separations using low thermal mass technology can be greener because of energy savings offered by this technology. In liquid chromatography the focus should be on the reduction of solvent consumption and replacement of toxic and environmentally hazardous solvents with more benign alternatives. Multidimensional separation techniques have the potential to make the analysis greener in both GC and LC. The environmental impact of the method is often determined by the location of the instrument with respect to the sample collection point. PMID:23932374

P?otka, Justyna; Tobiszewski, Marek; Sulej, Anna Maria; Kupska, Magdalena; Górecki, Tadeusz; Namie?nik, Jacek

2013-08-01

299

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.

300

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

301

Impact of Transradial Coronary Procedures on Radial Artery Function.  

PubMed

We evaluated the impact of transradial coronary procedures on the vasodilatory function of the radial artery. A total of 65 patients who underwent transradial coronary procedures were enrolled. All patients were examined with B-mode high-resolution ultrasound. Radial artery baseline diameter and response to flow-mediated dilation (FMD) and nitroglycerin-mediated dilation (NMD) were measured in the right radial artery. The FMD of the right radial artery was 11.5%, 4.1%, and 0.7%, respectively, before the procedures, 1 day, and 3 months after the procedures (P < .05 at 1 day, P < .01 at 3 months). The NMD of the right radial artery was 17.6%, 5.4%, and 6.3%, respectively, before the procedures, 1 day, and 3 months after the procedures (P < .05 at 1 day, P < .05 at 3 months). Transradial coronary procedures decrease radial artery FMD and NMD resulting in immediate and persistent blunting of vasodilatory function. PMID:23460113

Yan, Zhenxian; Zhou, Yujie; Zhao, Yingxin; Zhou, Zhiming; Yang, Shiwei; Wang, Zhijian

2013-03-01

302

Free flow electrophoresis coupled with liquid chromatography–mass spectrometry for a proteomic study of the human cell line (K562\\/CR3)  

Microsoft Academic Search

The requirement for prefractionation in proteomic analysis is linked to the challenge of performing such an analysis on complex biological samples and identifying low level components in the presence of numerous abundant housekeeping and structural proteins. The employment of a preliminary fractionation step results in a reduction of complexity in an individual fraction and permits more complete liquid chromatography\\/mass spectrometry

Yonghui Wang; William S. Hancock; Gerhard Weber; Christoph Eckerskorn; Darryl Palmer-Toy

2004-01-01

303

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

Microsoft Academic Search

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

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

2010-01-01

304

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

Microsoft Academic Search

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 (~1 mm in diameter) on a

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

2010-01-01

305

Pulse accumulation, radial heat conduction, and anisotropic thermal conductivity in pump-probe transient thermoreflectance  

Microsoft Academic Search

The relationship between pulse accumulation and radial heat conduction in pump-probe transient thermoreflectance (TTR) is explored. The results illustrate how pulse accumulation allows TTR to probe two thermal length scales simultaneously. In addition, the conditions under which radial transport effects are important are described. An analytical solution for anisotropic heat flow in layered structures is given, and a method for

Aaron J. Schmidt; Xiaoyuan Chen; Gang Chen

2008-01-01

306

An enhanced radial basis function network for short-term electricity price forecasting  

Microsoft Academic Search

This paper proposed a price forecasting system for electric market participants to reduce the risk of price volatility. Combining the Radial Basis Function Network (RBFN) and Orthogonal Experimental Design (OED), an Enhanced Radial Basis Function Network (ERBFN) has been proposed for the solving process. The Locational Marginal Price (LMP), system load, transmission flow and temperature of the PJM system were

Whei-Min Lin; Hong-Jey Gow; Ming-Tang Tsai

2010-01-01

307

Axial and radial water transport and internal water storage in tropical forest canopy trees  

Microsoft Academic Search

Heat and stable isotope tracers were used to study axial and radial water transport in relation to sapwood anatomical characteristics and internal water storage in four canopy tree species of a seasonally dry tropical forest in Panama. Anatomical characteristics of the wood and radial profiles of sap flow were measured at the base, upper trunk, and crown of a single

Shelley A. James; Frederick C. Meinzer; Guillermo Goldstein; David Woodruff; Timothy Jones; Teresa Restom; Monica Mejia; Michael Clearwater; Paula Campanello

2003-01-01

308

Systematic optimisation and evaluation of on-line, off-line and stop-flow comprehensive hydrophilic interaction chromatography×reversed phase liquid chromatographic analysis of procyanidins. Part II: application to cocoa procyanidins.  

PubMed

Procyanidins present a severe analytical challenge due to their structural complexity and diversity. Comprehensive two-dimensional hydrophilic interaction chromatography×reversed-phase liquid chromatography (HILIC×RP-LC) provides a highly efficient separation system for procyanidins. In the first part of this contribution a systematic approach for the optimisation and evaluation of HILIC×RP-LC analyses in on-line, off-line and stop-flow modes was presented. The three systems were compared in terms of peak capacity, the number of peaks produced per unit time as well as the total analysis time required to carry out such analyses by taking under-sampling, degree of orthogonality and stop-flow band-broadening into account. In this paper, the experimental verification of these findings using cocoa procyanidins as an application is presented. The results show that while optimisation procedures based on theoretical considerations remain largely valid in practice, several important experimental considerations should also be taken into account to achieve maximum performance in all three modes of HILIC×RP-LC. On-line analysis provides an effective tool for the screening of procyanidin content within reasonable times, provided that under-sampling of first dimension peaks is minimised. Off-line- and stop-flow HILIC×RP-LC analyses on the other hand are more suited for the detailed analysis of complex procyanidin fractions, with the latter being shown to be a promising automated alternative providing the same performance as the off-line approach. Experimental data presented verify the conclusion that stop-flow operation has a negligible effect on first dimension band broadening under the optimised experimental conditions used. PMID:23570856

Kalili, Kathithileni M; de Villiers, André

2013-03-17

309

Radial sensitivity of elastic scattering  

SciTech Connect

A new technique has been developed, employing a localized perturbation of the radial nuclear optical potential, which permits direct investigation of the sensitivities of optical model analysis of elastic scattering data to the details of the radial potential. It is found that both light- and heavy-ion scattering probe primarily the nuclear surface region. Higher energy scattering data probe further into the interior than lower energy data. The value of the potential at the center of the nucleus cannot be determined, but only inferred if a fixed parametrization such as Woods-Saxon geometry is specified. In addition, it is found that the region of radial sensitivity of the imaginary potential is systematically closer to the center of the nucleus than is that of the real potential.

Cramer, J.G.; DeVries, R.M.

1980-07-01

310

Immunoaffinity chromatography  

Microsoft Academic Search

The basic procedure of immunoaffinity chromatography (IAC) is described. The insoluble support matrices available for IAC\\u000a and their activation chemistries, including some of the most recently introduced, are reviewed. Means of selecting the most\\u000a appropriate monoclonal antibody (MAb) are described, although an empirical approach is still required for the final choice\\u000a of antibody. Precise methods of runing IAC columns are

George W. Jack

1994-01-01

311

LC-LC, Low Cost Liquid Chromatography. II. In-Line Flow-Preparation of Eluents of Fixed pHs  

Microsoft Academic Search

Conventional preparation of the weak aqueous eluent for reversed phase liquid chromatography by weighing, pipeting, and\\/or titrating materials can be time consuming, poorly reproducible, and require storage of many containers of final buffer. Stored buffers can become contaminated by vapors, container-leached materials, or microbes.This paper discribes a novel approach for preparing eluents in which LC-grade water is drawn through lengths

Vern Berry; Victor Pretorius

1990-01-01

312

Automated determination of levodopa and carbidopa in plasma by high-performance liquid chromatography-electrochemical detection using an on-line flow injection analysis sample pretreatment unit  

Microsoft Academic Search

An automated analytical procedure is described for the parallel determination of l-3,4-dihydroxyphenylalanine (levodopa, l-dopa, LD) and the analogous hydrazine compound carbidopa (CD) in dog plasma by ion-pair high-performance liquid chromatography with electrochemical detection (HPLC-ED). After deproteinization of the plasma samples with perchloric acid the catecholamines were extracted from the supernatant by adsorption on a small column filled with alumina. The

A. Tolokán; I. Klebovich; K. Balogh-Nemes; G. Horvai

1997-01-01

313

An improved flow analysis–ion chromatography method for determination of cationic and anionic species at trace levels in Antarctic ice cores  

Microsoft Academic Search

A method was developed for the quantitative determination of cations and anions in Antarctic ice cores at ?gL?1 and sub-?gL?1 levels by ion chromatography (IC), after ultra-clean decontamination procedures. Strict manipulation and decontamination procedures were used in sub-sampling, in order to minimise sample contamination. Na+, NH4+, K+, Mg2+ and Ca2+ were determined by 12-min isocratic elution (H2SO4 eluent). Contemporaneously, in

Andrea Morganti; Silvia Becagli; Emiliano Castellano; Mirko Severi; Rita Traversi; Roberto Udisti

2007-01-01

314

Astrometric versus Spectroscopic Radial Velocities  

Microsoft Academic Search

The radial velocity of a star, as deduced from wavelength shifts, does not merely contain the true velocity of the stellar center of mass but also components arising from dynamics in the star's atmosphere, gravitational redshifts, and other effects. For the Sun, the segregation of such effects has been possible because the relative Sun-Earth motion is accurately known from planetary

D. Dravins; D. Gullberg; L. Lindegren; S. Madsen

1999-01-01

315

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

316

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

317

Gas 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 gas chromatography and its application in discovering the amount of pesticide in fruit.Flash player is required to view and participate in this interactive learning unit.

2012-11-20

318

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

319

Vallecito Dam Flow Measurement and Weir Calibration.  

National Technical Information Service (NTIS)

Recent modifications to the Vallecito Dam outlet works structure have caused increased turbulence near the outlet works flow measurement device, making flow measurements unreliable. In addition, no accurate measure of flow through the spillway radial gate...

R. George

1994-01-01

320

Calculation of heat transfer in a radially rotating coolant passage  

SciTech Connect

The three-dimensional flow field and heat transfer in a radially rotating coolant passage are studied numerically. The passage chosen has a square cross section with smooth isothermal walls of finite length. The axis rotation is normal to the flow direction with the flow radially outward. The effects of Coriolis forces, centrifugal buoyancy, and fluid Reynolds number on the flow and heat transfer have all been considered. The analysis has been performed by using a fully elliptic, three-dimensional, body-fitted computational fluid dynamics code based on pressure correction techniques. The numerical technique employs a multigrid iterative solution procedure and the standard k [minus] [epsilon] turbulence model for both the hydrodynamics and heat transfer. The effect of rotation is included by considering the governing equations of motion in a relative frame of reference that moves with the passage. The consequence of rotation is to bring higher velocity fluid from the core to the trailing surface, thereby increasing both the friction and heat transfer at this face. At the same time, the heat transfer is predicted to decrease along the leading surface. The effect of buoyancy is to increase the radial velocity of the fluid, thus generally increasing the heat transfer along both the leading and trailing surfaces. These effects and trends that have been predicted are in agreement with experimental heat transfer data available in the literature. The quantitative agreement with the data was also found to be quite satisfactory.

Tolpadi, A.K. (General Electric Corporate Research and Development, Schenectady, NY (United States))

1994-12-01

321

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

2013-04-27

322

Radial coordinates for conformal blocks  

NASA Astrophysics Data System (ADS)

We develop the theory of conformal blocks in CFTd expressing them as power series with Gegenbauer polynomial coefficients. Such series have a clear physical meaning when the conformal block is analyzed in radial quantization: individual terms describe contributions of descendants of a given spin. Convergence of these series can be optimized by a judicious choice of the radial quantization origin. We argue that the best choice is to insert the operators symmetrically. We analyze in detail the resulting “?-series” and show that it converges much more rapidly than for the commonly used variable z. We discuss how these conformal block representations can be used in the conformal bootstrap. In particular, we use them to derive analytically some bootstrap bounds whose existence was previously found numerically.

Hogervorst, Matthijs; Rychkov, Slava

2013-05-01

323

Radial Photonic Crystals for Microwave Operation.  

National Technical Information Service (NTIS)

We analyze the properties of electromagnetic metamaterials with anisotropic constitutive parameters. Particularly, we analyze the so-called Radial Photonic Crystals, which are radially periodic structures verifying the Bloch theorem. This type of crystals...

A. Diaz-Rubio D. Torrent F. Cervera J. Carbonell M. A. Kirleis

2012-01-01

324

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

2013-09-03

325

Clasping of subscapular artery by radial nerve.  

PubMed

The present study is about an abnormal origin of radial nerve from Posterior cord of brachial plexus .Here radial nerve was arising as two roots from the posterior cord of brachial plexus. One root was passing posterior to the subscapular artery and other root anterior and the artery was situated between the two roots of the radial nerve. Further down both the roots united to form the trunk of the radial nerve. PMID:18604032

Kuwar, R B; Bilodi, A K S

326

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

327

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.  

National Technical Information Service (NTIS)

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 lean...

T. Katsanis W. D. Mcnally

1977-01-01

328

Implementing radial motion to the booster simulation  

SciTech Connect

It's a puzzle that high intensity beams prefer a particular radial motion during transition in the Booster, and the result of removing such a radial motion is to increase the transition loss. In order to understand this observation, the radial motion should be taken into account in the longitudinal simulation.

Yang, Xi; /Fermilab

2007-04-01

329

Nonstandard jump functions for radially symmetric shock waves  

SciTech Connect

Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic shock waves. It is assumed that the shock wave jumps occur on infinitesimal intervals, and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic shock waves coincide in a nonstandard sense for a specified density jump function

Baty, Roy S.; Tucker, Don H.; Stanescu, Dan

2008-10-01

330

Exploring the speed limits of liquid chromatography using shear-driven flows through 45 and 85 nm deep nano-channels.  

PubMed

We explored the possibility to perform high speed and high efficiency liquid chromatographic separations in channels with a sub-100 nm depth. The mobile phase flow through these nano-channels was generated using the shear-driven flow principle to generate high speed flows which were the equivalent of a 12?000 bar pressure-driven flow. It was found that the ultra-fast mass transfer kinetics prevailing in this range of small channel depths allow to drastically reduce the C-term contribution to band broadening, at least up to the upper speed limit of our current set-up (7 mm s(-1) mobile phase velocity), leaving the inescapable molecular diffusion (i.e., B-term band broadening) as the sole detectable source of band broadening. Due to the greatly reduced mass transfer limitations, 50?000 to 100?000 theoretical plates could be generated in the span of 1 to 1.5 seconds. This is nearly two orders of magnitude faster than the best performing commercial pressure-driven UHPLC-systems. With the employed channel depths, we appear to have struck a practical lower limit for the channel miniaturization of shear-driven flows. Despite the use of channel substrates with the highest grades of optical flatness, the overall substrate waviness (on the order of some 5 to 10 nm) can no longer be neglected compared to the etched channel depth, which in turn significantly influenced the local retention factor and band broadening. PMID:23965574

De Bruyne, Selm; De Malsche, Wim; Fekete, Veronika; Thienpont, Hugo; Ottevaere, Heidi; Gardeniers, Han; Desmet, Gert

2013-08-21

331

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

PubMed

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 data: packed pressure-flow, open column pressure-flow, and critical velocity. The robustness of the model has been demonstrated for MabSelect, SP 650M, Butyl Sepharose 4 FF and several other agarose-based and polymethacrylate-based resins. The predicted critical velocities are on average within +/-5% of observations. A simple modification to the Blake-Kozeny permeability expression allows accurate prediction of packed bed pressure-flow explicitly from compression factor, packed bed height, and settled bed inter-particle porosity. The model provides limits on mobile phase velocity and on operating pressure-flow as a function of bed height, particle size, and resin rigidity, and allows exploration of commercial manufacturing scenarios to identify scalable process time and cycle number. PMID:18374935

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

2008-03-13

332

Overcurrent Protection for the IEEE 34Node Radial Test Feeder  

Microsoft Academic Search

The IEEE 34-node radial test feeder is a benchmark circuit for validating results from existing and novel load-flow algorithms. This paper discusses the addition of overcurrent protection (OCP) to the test feeder using off-the-shelf protective devices. The OCP scheme includes a recloser near the substation and fuses at the laterals. These OCP devices represent the conventional types present in most

Hamed B. Funmilayo; James A. Silva; Karen L. Butler-Purry

2012-01-01

333

Fabrication and test of radial grooved micro heat pipes  

Microsoft Academic Search

This paper describes the development of radial grooved micro heat pipes (MHPs) with a three-layer structure. The MHPs were designed to allow separation of the liquid and vapor flow to reduce the viscous shear force. The 5×5 cm2 MHP array was fabricated by using bulk micromachining and eutectic bonding techniques on 4-in. (100) silicon wafers. Experiments were undertaken to evaluate

Shung-Wen Kang; Sheng-Hong Tsai; Hong-Chih Chen

2002-01-01

334

New pinch for the ion toroidal rotation generated by a radial pressure gradient in a tokamak  

NASA Astrophysics Data System (ADS)

Previous work has described a turbulent pinch of toroidal angular momentum due to the Coriolis drift in a rotating frame. This pinch is only valid if the ion toroidal rotation is generated by a radial electric field only. It is well known that the ion rotation has two pieces: the one generated by the radial electric field and the other by the radial pressure gradient. We propose a new pinch mechanism for the piece of the rotation generated by the radial pressure gradient, which is important for a sub-sonic flow or the flow in the pedestal where the radial electric field and the pressure gradient are similar in size. The pressure gradient does not modify the particle orbits but imparts rotation to the plasma due to the finite orbit width effect (e.g. a neoclassical flow), while the radial electric field changes both the orbits and the rotation. We evaluate the pinch of the piece of the rotation generated by the pressure gradient using a nonlinear gyrokinetic analysis, and compare it with the pinch due to the piece of the rotation by the radial electric field that is well described by the Coriolis drift analysis. The parallel dynamics and the trapped electron responses are important to determine the size of the pinches for ion temperature gradient (ITG) driven turbulence.

Lee, Jungpyo; Barnes, Michael; Parra, Felix

2012-10-01

335

Fundamental studies of radial wave thermoacoustic engines  

NASA Astrophysics Data System (ADS)

Our research is about arbitrary geometry thermoacoustic engines. The specific geometry studied in detail is the radial wave arrangement. Formal theory and the short stack approximation were derived for this geometry and were used to pursue an answer to the following question: Radial or plane wave thermoacoustic refrigerators? To date, the plane wave refrigerator appears to be the best overall compromise refrigerator, though the radial wave refrigerator has a higher cooling capacity. An evolving numerical design program has been enhanced to include radial or plane wave engines with variable plate spacing and both plane and radial wave resonators simultaneously with application to driving radial wave refrigerators with heat driven plane wave sound sources. Our experiments have mainly been aimed at radial wave prime movers for the purposes of validating the theory and investigating the large amplitude behavior. Heat exchanger design is a critical issue.

Arnott, W. P.

1995-06-01

336

Radial side (1D) tears.  

PubMed

The triangular fibrocartilage complex (TFCC) is the key structure at the wrist that facilitates the rotation of the radius and the carpus on the distal ulnar. The radial or type 1D tears of the TFCC are uncommon, but they pose a major disruption of the articular contact between the carpus and the distal ulna. The tears can heal by arthroscopically repairing the TFCC back to the radius using sutures through bone tunnels. This procedure allows patients to return to their work and sports activities with significant recovery of strength and range of motion. PMID:21871347

Trumble, Thomas

2011-08-01

337

PRECISION RADIAL VELOCITIES WITH CSHELL  

SciTech Connect

Radial velocity (RV) identification of extrasolar planets has historically been dominated by optical surveys. Interest in expanding exoplanet searches to M dwarfs and young stars, however, has motivated a push to improve the precision of near-infrared RV techniques. We present our methodology for achieving 58 m s{sup -1} precision in the K band on the M0 dwarf GJ 281 using the CSHELL spectrograph at the 3 m NASA Infrared Telescope Facility. We also demonstrate our ability to recover the known 4 M{sub JUP} exoplanet Gl 86 b and discuss the implications for success in detecting planets around 1-3 Myr old T Tauri stars.

Crockett, Christopher J.; Prato, L. [Lowell Observatory, 1400 W Mars Hill Road, Flagstaff, AZ 86001 (United States); Mahmud, Naved I.; Johns-Krull, Christopher M. [Department of Physics and Astronomy, Rice University, MS-108, 6100 Main Street, Houston, TX 77005 (United States); Jaffe, Daniel T. [Department of Astronomy, University of Texas, R.L. Moore Hall, Austin, TX 78712 (United States); Beichman, Charles A., E-mail: crockett@lowell.edu, E-mail: lprato@lowell.edu, E-mail: naved@rice.edu, E-mail: cmj@rice.edu, E-mail: dtj@astro.as.utexas.edu [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

2011-07-10

338

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

339

Radial and vertical mixing in protoplanetary accretion disks  

NASA Astrophysics Data System (ADS)

Crystalline silicates and aliphatic hydrocarbons in comets as well as deuterated species in several solar system bodies indicate an extensive radial mixing in the primodial solar nebula, i.e. the protoplanetary accretion disk of our solar system. To study the radial transport of matter within protoplanetary disks it is essential to resolve the vertical direction since matter is mixed radially outward by vertical `detour' in the complex flow of the disk. In this work we perform numerical models of protoplanetary accretion disks with radial and vertical mixing by solving a set of 2-dimensional diffusion-advection-reaction equations for different tracers self-consistently with the set of disk equations in the 1+1-dimensional approximation. Tracers are silicate grains (olivine, pyroxene) which anneal in the warm inner parts of the disk and carbonaceous grains which combust by surface reaction with OH molecules. Considerable fractions of crystallized silicates as well as methan as a product of carbon combustion are transported to the location of formation of comets afar from the protosun.

Wehrstedt, Michael; Gail, H.-P.

340

Magnetically suspended centrifugal blood pump with a radial magnetic driver.  

PubMed

A new magnetic bearing has been designed to achieve a low electronic power requirement and high stiffness. The magnetic bearing consists of 1) radial passive forces between the permanent magnet ring mounted inside the impeller rotor and the electromagnet core materials in the pump casing and 2) radial active forces generated by the electromagnets using the two gap sensor signals. The magnetic bearing was assembled into a centrifugal rotary blood pump (CRBP) driven with a radial, magnetic coupled driver. The impeller vane shape was designed based upon the computational fluid dynamic simulation. The diameter and height of the CRBP were 75 mm and 50 mm, respectively. The magnetic bearing system required the power of 1.0-1.4 W. The radial impeller movement was controlled to within +/- 10 microm. High stiffness in the noncontrolled axes, Z, phi, and theta, was obtained by the passive magnetic forces. The pump flow of 5 L/min against 100 mm Hg head pressure was obtained at 1,800 rpm with the electrical to hydraulic efficiency being greater than 15%. The Normalized Index of Hemolysis (NIH) of the magnetic bearing CRBP was one fifth of the BioPump BP-80 and one half of the NIKKISO HPM-15 after 4 hours. The newly designed magnetic bearing with two degrees of freedom control in combination with optimized impeller vane was successful in achieving an excellent hemolytic performance in comparison with the clinical centrifugal blood pumps. PMID:15745136

Hoshi, Hideo; Katakoa, Kiroyuki; Ohuchi, Katsuhiro; Asama, Jun-ichi; Shinshi, Tadahiko; Shimokohbe, Akira; Takatani, Setsuo

341

Determination of Gentian Violet in human urine and poultry feed by high performance liquid chromatography with electrochemical detection using a carbon fibre microelectrode flow cell  

Microsoft Academic Search

A sensitive and relatively selective high performance liquid chromatographic method for the determination of Gentian Violet (GV) in human urine and chicken feed is described. The method is based on solid-phase extraction, with subsequent reversed-phase chromatographic separation on a cyano column and amperometric detection using a carbon fibre microelectrode flow cell operated at + 1.3 V. The peak currents were

Kamal A. Sagar; Malcolm R. Smyth; Margarita Rodriguez; Paulino Tunon Blanco

1995-01-01

342

Rapid isolation of biomarkers for compound specific radiocarbon dating using high-performance liquid chromatography and flow injection analysis–atmospheric pressure chemical ionisation mass spectrometry  

Microsoft Academic Search

Repeated semi-preparative normal-phase HPLC was performed to isolate selected biomarkers from sediment extracts for radiocarbon analysis. Flow injection analysis–mass spectrometry was used for rapid analysis of collected fractions to evaluate the separation procedure, taking only 1 min per fraction. In this way 100–1000 ?g of glycerol dialkyl glycerol tetraethers, sterol fractions and chlorophyll-derived phytol were isolated from typically 100 g

Rienk H Smittenberg; Ellen C Hopmans; Stefan Schouten; Jaap S Sinninghe Damsté

2002-01-01

343

Alumina supported Co-Mo oxides as a catalyst for hydrodesulphurisation of organic sulfides and disulphides using stopped flow gas chromatography  

SciTech Connect

The authors present a model study on the hydrodesulphurization of dimethyl sulphide, di n-prophyl sulphide, di n-butyl sulphide and dimethyl disulphide on Co-Mo-Al/sub 2/O/sub 3/ surface conducted using stopped-flow chromatographic technique. The plots for the rates of hydrocarbon formation agree well with the first order reaction at the surface of the catalyst.

Ali, L.H.; Sulaiman, S.T.; AlTamer, M.Y. (Chemistry Dept. College of Science, Univ. of Mosul (IQ))

1989-01-01

344

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

345

Effect of magnetic field on radial dopant segregation in crystal growth by traveling heater method  

Microsoft Academic Search

A three dimensional time dependent computational model is developed to simulate the melt flow, heat transfer and the dopant transport during the growth of Si1?xGex semiconductor crystals by traveling heater method. The effect of static magnetic fields of different orientations on the radial and axial segregation of dopant is analyzed. It is observed that the flow oscillations are damped and

H. Sadrhosseini; I. Sezai

2010-01-01

346

Effects of axial tension and reduced air pressure on the radial thermal conductivity of a stranded conductor  

Microsoft Academic Search

Analysis of the radial flow of heat in a multi-layer stranded conductor carrying current indicates that most of the heat is conducted through the very thin air gaps at the contacts between strands in adjacent layers and through the triangular or rectangular voids between layers. The theory predicts that, with constant current, the radial temperature difference increases as the axial

V. T. Morgan; R. D. Findlay

1993-01-01

347

A novel approach for sensitivity calculations in the radial distribution system  

Microsoft Academic Search

In this paper, a novel approach for calculating the sensitivities of active\\/reactive power loss and voltage magnitudes with respect to active\\/reactive power injection at any bus in the radial distribution system is presented. In a radial distribution system, the changes in bus voltages and branch flows due to active\\/reactive power injection at any bus depend on the network topology. The

Dheeraj Kumar Khatod; Vinay Pant; Jaydev Sharma

2006-01-01

348

Radial MRI techniques for obtaining motion-insensitive high-resolution images with variable contrast  

Microsoft Academic Search

The advantages of multi-shot radial fast spin-echo (RAD-FSE) MRI methods over conventional Fourier transformed (FT) MRI methods for obtaining high-resolution images with minimal motion- and flow-induced artifact are presented. The utility of post-processing methods used to obtain images with different T2-weighted contrast as well as T2 maps from a single radial set is also described. Applications are shown for three

Maria I. Altbach; Theodore P. Trouard; Arthur F. Gmitro

2002-01-01

349

An automated method for the measurement of a range of tyrosine kinase inhibitors in human plasma or serum using turbulent flow liquid chromatography-tandem mass spectrometry.  

PubMed

Tyrosine kinase inhibitors (TKIs) are used to treat a number of cancers, including chronic myeloid leukaemia and hepatocellular carcinoma. Therapeutic drug monitoring (TDM) may be indicated to (1) monitor adherence, (2) guide dosage, and (3) minimise the risk of drug-drug interactions and dose-related toxicity. On-line, automated sample preparation provided by TurboFlow technology (ThermoFisher Scientific) in conjunction with the sensitivity and selectivity of tandem mass spectrometry (MS/MS) detection may be applied to the analysis of single drugs and metabolites. We report the use of TurboFlow LC-MS/MS for the analysis of nine TKIs and metabolites (imatinib, N-desmethylimatinib, dasatinib, nilotinib, erlotinib, gefitinib, lapatinib, sorafenib, sunitinib) in human plasma or serum for TDM purposes. An Aria Transcend TLX-II system coupled with a TSQ Vantage was used. Samples (50 ?L) were vortex mixed with internal standard solution (150 ?L imatinib-D(8), gefitinib-D(8), sunitinib-D(10), and nilotinib-(13)C (2) (15) N(2) in acetonitrile) and, after centrifugation 100 ?L supernatant were injected directly onto a 50 × 0.5-mm Cyclone TurboFlow column. Analytes were focussed onto a 50 × 2.1-mm (3 ?m) Hypersil GOLD analytical column and eluted with an acetonitrile/water gradient. Analytes were monitored in selected reaction monitoring mode (positive APCI). Total analysis time was 7 min without multiplexing. Calibration was linear (R(2) > 0.99) for all analytes. Inter- and intra-assay precision (in percent relative standard deviation, RSD) was <11 % and accuracy 89-117 % for all analytes. No matrix effects were observed. This method is suitable for high-throughput TDM in patients undergoing chronic therapy with TKIs and has been utilised in the analysis of clinical samples. PMID:22526649

Couchman, L; Birch, M; Ireland, R; Corrigan, A; Wickramasinghe, S; Josephs, D; Spicer, J; Flanagan, R J

2012-04-14

350

Hydrodesulfurization of Qaiyarah 80-205 sup 0 C naphtha fraction of alumina supported Co-Mo-oxides; Part 2: Using stopped flow gas chromatography  

SciTech Connect

The authors report the effective desulfurization of Qaiyarah 80-205{sup 0}C, naphtha fraction on alumina supported Co-Mo oxides, assembled in a GC column using H{sub 2} as a carrier gas and the stopped-flow technique. Over 90% of sulfur was removed from this partially cracked naphtha and a similar result (Ca 90%) was obtained when hydrodesulfurizing an acid-base treated naphtha. /sup 1/H nmr studies on the chromatographically separated hydrodesulfurized fractions revealed interesting structural parameters which leads to suggestions related to the occurrence of a reforming reaction and the liberation of fresh H{sub 2} gases which further promotes hydrodesulfurization.

Ali, L.H.; Sulaiman, S.T.; AlTamer, M.Y. (Chemistry Dept., College of Science Univ. of Mosul, Mosul (IQ))

1990-04-01

351

What patients should know about radial keratotomy.  

PubMed

Radial keratotomy is a relatively new, widely advertised procedure that promises patients with myopia 20/20 vision without corrective lenses. However, radial keratotomy sometimes does not fulfill this promise. New studies have reported numerous cases in which patients were not helped or were actually harmed by radial keratotomy. Also, its long-term effects are unknown. Family physicians should advise patients to approach the procedure with caution. PMID:3706095

Lundergan, M K; White, G L; Murdock, R T

1986-05-01

352

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...

353

Radial head prosthesis after fracture of radial head with associated elbow instability  

Microsoft Academic Search

Introduction: Fractures of the radial head and associated elbow instability can be treated with operation with radial head prosthesis.\\u000a In this study, we evaluate function 1–7 years after implantation and also function after removal of five prostheses. Material and methods: Eighteen patients with radial head fracture and associated elbow instability were evaluated 3.7 years (1–7) after implantation\\u000a of a radial head prosthesis.

Per Wretenberg; Anne Ericson; André Stark

2006-01-01

354

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

2013-07-25

355

The study of the influence of temperature and initial glucose concentration on the fermentation process in the presence of Saccharomyces cerevisiae yeast strain immobilized on starch gels by reversed-flow gas chromatography.  

PubMed

The technique of reversed-flow gas chromatography (RFGC) was employed for the determination of the alcoholic fermentation phases and of kinetic parameters for free and immobilized cell systems, at different initial glucose concentrations and temperature values. In addition to this, due to its considerable advantages over other techniques, RFGC was used for the characterization of a new biocatalyst, yeast cells immobilized on starch gel, and especially wheat starch gel. Immobilization of wine yeast Saccharomyces cerevisiae AXAZ-1 was accomplished on wheat and corn starch gels in order to prepare new biocatalysts with great interest for the fermentation industry. The RFGC led with great accuracy, resulting from a literature review, to the determination of reaction rate constants and activation energies at each phase of the fermentation processes. A maximum value of rate constants was observed at initial glucose concentration of 205 g/L, where a higher number of yeast cells was observed. The increase of glucose concentrations had a negative influence on the growth of AXAZ-1 cells and rate constants were decreased. The decrease of fermentation temperature caused a substantial reduction in the viability of immobilized cells as well as in rate constant values. Activation energies of corn starch gel presented lower values than those of wheat starch gel. However, the two supports showed higher catalytic efficiency than free cell systems, proving that starch gels may act as a promoter of the catalytic activity of the yeast cells involved in the fermentation process. PMID:22897770

Lainioti, G Ch; Kapolos, J; Koliadima, A; Karaiskakis, G

2012-01-01

356

Radial spoke proteins of Chlamydomonas flagella  

Microsoft Academic Search

The radial spoke is a ubiquitous component of '9+2' cilia and flagella, and plays an essential role in the control of dynein arm activity by relaying signals from the central pair of microtubules to the arms. The Chlamydomonas reinhardtii radial spoke contains at least 23 proteins, only 8 of which have been characterized at the molecular level. Here, we use

Pinfen Yang; Dennis R. Diener; Chun Yang; Takahiro Kohno; Gregory J. Pazour; Jennifer M. Dienes; Nathan S. Agrin; Stephen M. King; Winfield S. Sale; Ritsu Kamiya; Joel L. Rosenbaum; George B. Witman

2006-01-01

357

Radial force in a bearingless reluctance motor  

NASA Astrophysics Data System (ADS)

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.

Chiba, Akira; Rahman, M. A.; Fukao, Tadashi

1991-03-01

358

Phoneme classification experiments using radial basis functions  

Microsoft Academic Search

The application of a radial basis functions network to a static speech pattern classification problem is described. The radial basis functions network offers training times two to three orders of magnitude faster than backpropagation, when training networks of similar power and generality. Recognition results compare well with those obtained using backpropagation and a vector-quantized hidden Markov model on the same

Steve Renals; Richard Rohwer

1989-01-01

359

Approximation and Radial-Basis-Function Networks  

Microsoft Academic Search

This paper concerns conditions for the approximation of functions in certain general spaces using radial-basis-function networks. It has been shown in recent papers that certain classes of radial-basis-function networks are broad enough for universal approximation. In this paper these results are considerably extended and sharpened.

Jooyoung Park; Irwin W. Sandberg

1993-01-01

360

Radial segregation driven by axial convection  

Microsoft Academic Search

We experimentally study the mixing of binary granular systems in a horizontal rotating cylinder. When materials have the same size and differ by dynamic angle of repose only, we observe an axial transport of matter that generates transient radial segregation. The system then evolves towards homogeneity. If materials differ by density also radial segregation becomes steady. A mechanism is suggested

A. C. Santomaso; L. Petenò; P. Canu

2006-01-01

361

Modern Physics Problem: Radial Wave Functions  

NSDL National Science Digital Library

The two Physlets show a density plot of the Hydrogenic wavefunction and the solution to the radial equation. The word "density" refers to a method for plotting 3-D information on a two dimensional screen. Here it has nothing to do with the probability density in quantum mechanics. The radial solutions used here are the associated Laguerre polynomials scaled with a0 = 1.

Christian, Wolfgang; Belloni, Mario

2007-03-03

362

Basic Principles of Chromatography  

NASA Astrophysics Data System (ADS)

Chromatography has a great impact on all areas of analysis and, therefore, on the progress of science in general. Chromatography differs from other methods of separation in that a wide variety of materials, equipment, and techniques can be used. [Readers are referred to references (1-19) for general and specific information on chromatography.]. This chapter will focus on the principles of chromatography, mainly liquid chromatography (LC). Detailed principles and applications of gas chromatography (GC) will be discussed in Chap. 29. In view of its widespread use and applications, high-performance liquid chromatography (HPLC) will be discussed in a separate chapter (Chap. 28). The general principles of extraction are first described as a basis for understanding chromatography.

Ismail, Baraem; Nielsen, S. Suzanne

363

Applying Simple Chromatography  

NSDL National Science Digital Library

This activity involves chemistry, mystery, colors, and measurement. Students observe the composition of various inks by separating them via water-based chromatography. Students use what they learn about chromatography to solve a mystery involving a suspic

Eichinger, John

2009-05-15

364

Report: Affinity Chromatography.  

ERIC Educational Resources Information Center

|Supports, affinity ligands, immobilization, elution methods, and a number of applications are among the topics considered in this discussion of affinity chromatography. An outline of the basic principles of affinity chromatography is included. (JN)|

Walters, Rodney R.

1985-01-01

365

Anatomic Landmarks for the Radial Tunnel  

PubMed Central

Background: The posterior interosseous nerve (PIN) can be difficult to locate within the radial tunnel. The deep branch of the radial nerve (DBRN) enters the supinator muscle after passing under the arcade of Fröhse. It courses through the superficial portion of the supinator muscle to exit distally as the PIN. Anatomic landmarks could facilitate diagnosis and treatment of radial tunnel syndrome and aid in the injection and decompression of the radial nerve. Methods: Eighteen cadaveric arms were used to identify anatomic landmarks to facilitate location of the PIN. The landmarks used include the palpable proximal radial edge of the radial head, proximally, and the mid-width of the wrist, distally. The skin was incised along this longitudinal line through the fascia. Deep within this plane the PIN was identified exiting the distal edge of the superficial portion of the supinator muscle. The proximal and distal edges of the supinator muscle were measured from the proximal radial aspect of the radial head. In addition, the course of the DBRN was appreciated proximal and distal to the superficial part of the supinator muscle. Results: The PIN was identified to exit the superficial part of the supinator muscle at an average distance of 7.4 ± 0.4 cm distal to the proximal radial aspect of the radial head. Distal to the distal edge of the supinator muscle, the PIN passed along a longitudinal vector from the radial head to the mid-width point of the wrist. From within the supinator muscle the DBRN courses retrograde in an oblique direction toward the lateral edge of the distal most part of the biceps tendon. Conclusion: The anatomic landmarks of the radial head and the mid-width of the dorsal wrist can be used to predict the course and location of the PIN. The DBRN can be predicted to enter the superficial part of the supinator muscle approximately 3.5 cm distal to the radial head, and the PIN is predicted to exit the supinator at 7.5 cm distal to the radial head.

Hazani, Ron; Engineer, Nitin J.; Mowlavi, Arian; Neumeister, Michael; Lee, W.P. Andrew; Wilhelmi, Bradon J.

2008-01-01

366

Reinforced bead for a radial tire  

US Patent & Trademark Office Database

A tire for heavy loads, having an inextensible radial carcass ply anchored to a bead wire to form an upturn, the end of which is located at a radial distance from the base of the bead. Each bead is reinforced by at least two additional reinforcement armatures, one armature formed of radial inextensible metallic reinforcement elements and a second armature formed of metallic elements forming an angle with the circumferential direction, the first armature being formed of at least one ply wound around the anchoring bead wire on the inside of the carcass reinforcement to form two strands, such that the axially inner strand, between the radially lower end of its radially upper edge parallel to the meridian profile of the carcass reinforcement and its point of tangency with the anchoring bead wire, follows a rectilinear trace referred to as "shortest-path".

Auxerre; Pascal (Royat, FR)

2003-07-15

367

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.

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

2012-01-01

368

A Simple Algorithm to Implement Active Power Loss Allocation Schemes in Radial Distribution Systems  

NASA Astrophysics Data System (ADS)

In this paper, a brief overview of various active power loss allocation methods is presented. "Exact Method" of loss allocation, suitable for radial distribution systems, is chosen for implementation. Simple bus identification techniques are proposed to implement load flow and loss allocation. A detailed algorithm with some useful MATLAB codes are included to form various proposed arrays to perform the load flow and then allocate losses to various buses. The results for a 30-bus and a 69-bus radial test distribution system are presented.

Mishra, S.; Das, D.; Paul, S.

2012-09-01

369

Imposing Radiality Constraints in Distribution System Optimization Problems  

Microsoft Academic Search

Distribution systems commonly operate with a radial topology, so all models of optimization problems in these distribution systems should consider radiality in their formulation. This work presents a literature review, a critical analysis, and a proposal for incorporating the radiality constraints in mathematical models of optimization problems for radial distribution systems. The objective is to show that the radiality constraints

Marina Lavorato; John F. Franco; Marcos J. Rider; Rubén Romero

2012-01-01

370

Ice accretion on a radial inflow turbine blade  

SciTech Connect

A computational method for predicting ice accumulation on a radial inflow turbine blade has been developed. The method includes particle trajectory calculations based on a flow field solution, and icing analysis that takes the impinging liquid and formulates a heat balance equation on the surface of the blade. Since there are no known previous calculations or experiments to compare with the prediction of the present method, calculations for several ranges of parameters are performed in order to gain experience. Some qualitative predictions of ice shedding frequencies, types of ice that may be formed, and a design suggestion for reducing ice buildup is also made.

Hefazi, H.; Kaups, K. [California State Univ., Long Beach, CA (United States). Aerospace Engineering Dept.; Murry, R. [Allied Signal Inc., Torrance, CA (United States)

1996-07-01

371

NGC 789 radial velocities (Gim+, 1998)  

NASA Astrophysics Data System (ADS)

A total of 597 radial velocity observations for 112 stars in the ~1.6Gyr old open cluster NGC 7789 have been obtained since 1979 with the radial velocity spectrometer at the Dominion Astrophysical Observatory. The mean cluster radial velocity is -54.9+/-0.12km/s and the dispersion is 0.86km/s, from 50 constant velocity stars selected as members from this radial velocity study and the 1981 proper motion study of McNamara & Solomon (1981A&AS...43..337M). Twenty-five stars (32%) among 78 members are possible radial velocity variable stars, but no orbits are determined because of the sparse sampling. Seventeen stars are radial velocity nonmembers, while the membership estimates of six stars are uncertain. There is a hint that the observed velocity dispersion falls off at large radius: this may be due to the inclusion of long-period binaries preferentially in the central area of the cluster. The known radial velocity variables also seem to be more concentrated toward the center than members with constant velocity. Although this is significant at only the 85% level, when combined with the similar result of Raboud & Mermilliod (1994A&A...289..121R) for three other clusters, the data strongly support the conclusion that mass segregation is being detected. (2 data files).

Gim, M.; Hesser, J. E.; McClure, R. D.; Stetson, P. B.

1998-11-01

372

Determination of deoxynivalenol (vomitoxin) by high-performance liquid chromatography with electrochemical detection.  

PubMed

A rapid method for the analysis of deoxynivalenol (DON) was developed using high-performance liquid chromatography (HPLC) with reductive electrochemical detection (ED). Deoxynivalenol produced by Fusarium roseum growing on solid cornmeal and rice substrates and from naturally contaminated wheat was extracted and quantitated via ED. DON levels in wheat were verified by gas chromatography and structurally confirmed by mass spectrometry. DON was optimally resolved by HPLC employing a radially compressed octadecylsilane column and a mobile phase of deoxygenated methanol-40 mM borate buffer (35:65) at a flow-rate of 1.0 ml/min. Under these conditions DON exhibited an average retention time of 3.6 min. Reductive ED (-1.4 V) allowed a 12-fold increase in sensitivity and greater selectivity than classical UV absorption at 224 nm. A detection limit for DON of 25 pg/microliter was achieved under these conditions. The determination of DON in crude grain extracts was hindered by extractable interfering substances, whereas ED was more functional-group selective (i.e. reduction of the carbonyl moiety). ED permits a direct quantitation of DON from crude grain extracts and may facilitate the determination of this agent and associated metabolites in biological samples. PMID:3745365

Sylvia, V L; Phillips, T D; Clement, B A; Green, J L; Kubena, L F; Heidelbaugh, N D

1986-07-01

373

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

374

Scintillating lustre induced by radial fins.  

PubMed

Radial lines of Ehrenstein patterns induce illusory scintillating lustre in gray disks inserted into the central gaps (scintillating-lustre effect). We report a novel variant of this illusion by replacing the radial lines with white and black radial fins. Both white and gray disks inserted into the central gaps were perceived as scintillating, if the ratio of the black/white fin width were balanced (ie, close to 1.0). Thus, the grayness of the central disk is not a prerequisite for the scintillation. However, the scintillation was drastically reduced when the ratio was imbalanced. Furthermore, the optimal ratio depended on the color of the center disks. PMID:23145270

Takahashi, Kohske; Fukuda, Haruaki; Watanabe, Katsumi; Ueda, Kazuhiro

2012-02-21

375

Rotating stall control in a high-speed stage with inlet distortion. Part 1: Radial distortion  

SciTech Connect

This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An annular array of 12 jet-injectors located upstream of the rotor tip was used for forced response testing and to extend the compressor stable operating range. Results for radial distortion are reported in this paper. First, the effects of radial distortion on the compressor performance and the dynamic behavior were investigated. Control laws were designed using empirical transfer function estimates determined from forced response results. The transfer function indicated that the compressor dynamics are decoupled with radial inlet distortion, as they are for the case of undistorted inlet flow. Single-input-single-output (SISO) control strategies were therefore used for the radial distortion controller designs. Steady axisymmetric injection of 4 percent of the compressor mass flow resulted in a reduction in stalling mass flow of 9.7 percent relative to the case with inlet distortion and no injection. Use of a robust H{sub {infinity}} controller with unsteady nonaxisymmetric injection achieved a further reduction in stalling mass flow of 7.5 percent, resulting in a total reduction of 17.2 percent.

Spakovszky, Z.S.; Weigl, H.J.; Paduano, J.D. [Massachusetts Inst. of Technology, Cambridge, MA (United States). Gas Turbine Lab.; Schalkwyk, C.M. van [Scientific Systems Co., Woburn, MA (United States); Suder, K.L.; Bright, M.M. [NASA Lewis Research Center, Cleveland, OH (United States)

1999-07-01

376

Performance, resolving power, and radial ion distributions of a prototype nanoelectrospray ionization resistive glass atmospheric pressure ion mobility spectrometer.  

PubMed

In this article, we describe and characterize a novel ion mobility spectrometer constructed with monolithic resistive glass desolvation and drift regions. This instrument is equipped with switchable corona discharge and nanoelectrospray ionization sources and a Faraday plate detector. Following description of the instrument, pulsing electronics, and data acquisition system, we examine the effects of drift gas flow rate and temperature, and of the aperture grid to anode distance on the observed resolving power and sensitivity. Once optimum experimental parameters are identified, different ion gate pulse lengths, and their effect on the temporal spread of the ion packet were investigated. Resolving power ranged from an average value of 50 ms/ms for a 400-micros ion gate pulse, up to an average value of 68 ms/ms for a 100-micros ion gate pulse, and a 26-cm drift tube operated at 383 V cm(-1). Following these experiments, the radial distribution of ions in the drift region of the spectrometer was studied by using anodes of varying sizes, showing that the highest ionic density was located at the center of the drift tube. Finally, we demonstrate the applicability of this instrument to the study of small molecules of environmental relevance by analyzing a commercially available siderophore, deferoxamine mesylate, in both the free ligand and Fe-bound forms. Ion mobility experiments showed a dramatic shift to shorter drift times caused by conformational changes upon metal binding, in agreement with previous reversed-phase liquid chromatography observations. PMID:17854161

Kwasnik, Mark; Fuhrer, Katrin; Gonin, Marc; Barbeau, Katherine; Fernandez, Facundo M

2007-09-14

377

The radial flow of heat in an infinite cylinder  

Microsoft Academic Search

A solution is given to the problem of heat conduction in a solid cylinder of infinite length, the surface of which is subjected to a thermal flux which decreases linearly with time. This solution may be used to determine the transient temperatures occurring at the interface or at any point within two concentric cylinders which are in contact, one of

T P Newcomb

1958-01-01

378

ANALYSIS OF TRACER MIGRATION IN A DIVERGING RADIAL FLOW FIELD  

Microsoft Academic Search

Hydrodynamic dispersion is an important factor controlling contaminant migration in the subsurface environment. However, few comprehensive data sets exist for critically evaluating the impact of travel distance and site heterogeneity on solute dispersion. Therefore, a series of field-scale experiments using tritiated water (3H2O), and bromide (Br-) as tracers was conducted on the U.S. Department of Energy's Savannah River Site. For

J. C. Seaman; F. Majs; J. Singer; S. Aburime; S. O. Dennis; M. Wilson; P. M. Bertsch

2007-01-01

379

Atomic Physics Effects on IEC Ion Radial Flow  

NASA Astrophysics Data System (ADS)

A simple model for the effect of charge exchange and ion impact ionization of background gas on the performance of spherical, gridded IEC devices has been developed. Ions entering the intergrid region are not only accelerated by the falling electrostatic potential, but also produce a source of cold ions through charge exchange and ion impact ionization of the background gas. Charge exchange is treated as a loss of ions with finite energy and a corresponding source of cold ions. The cold ions are also accelerated by the potential and, in turn, produce additional cold ions. A formalism has been developed which includes the bouncing motion of ions in the electrostatic potential well and sums over all generations of cold ions. This leads to a Volterra integral equation for the resulting total cold ion source function. The integral equation is solved numerically, and the energy spectrum of the ion and fast neutral flux is calculated from the cold ion source function. Macroscopic quantities, such as the current collected by the cathode, and the fusion rate between ions and fast neutrals with the background gas, are calculated and compared with representative experimental values for the Wisconsin IEC device. The agreement is generally good. Extensions to the model, such as multiple ion species, are being developed. Research supported by the US Dept. of Energy under grant DE-FG02-04ER54745.

Emmert, G. A.

2005-10-01

380

Radial hydraulic conductivity along developing onion roots.  

PubMed

Although most studies have shown that water uptake varies along the length of a developing root, there is no consistent correlation of this pattern with root anatomy. In the present study, water movement into three zones of onion roots was measured by a series of mini-potometers. Uptake was least in the youngest zone (mean hydraulic conductivity, Lpr = 1.5 x 10(-7) +/- 0.34 x 10(-7) m MPa-1 s-1; +/- SE, n = 10 roots) in which the endodermis had developed only Casparian bands and the exodermis was immature. Uptake was significantly greater in the middle zone (Lpr = 2.4 x 10(-7) +/- 0.43 x 10(-7) m MPa-1 s-1; +/- SE, n = 10 roots) which had a mature exodermis with both Casparian bands and suberin lamellae, and continued at this level in the oldest zone in which the endodermis had also developed suberin lamellae (Lpr = 2.8 x 10(-7) +/- 0.30 x 10(-7) m MPa-1 s-1; +/- SE, n = 10 roots). Measurements of the hydraulic conductivities of individual cells (Lp) in the outer cortex using a cell pressure probe indicated that this parameter was uniform in all three zones tested (Lp = 1.3 x 10(-6) +/- 0.01 x 10(-6) m MPa-1 s-1; +/- SE, n = 60 cells). Lp of the youngest zone was lowered by mercuric chloride treatment, indicating the involvement of mercury-sensitive water channels (aquaporins). Water flow in the older two root zones measured by mini-potometers was also inhibited by mercuric chloride, despite the demonstrated impermeability of their exodermal layers to this substance. Thus, water channels in the epidermis and/or exodermis of the older regions were especially significant for water flow. The results of this and previous studies are discussed in terms of two models. The first, which describes maize root with an immature exodermis, is the 'uniform resistance model' where hydraulic resistances are evenly distributed across the root cylinder. The second, which describes the onion root with a mature exodermis, is the 'non-uniform resistance model' where resistances can be variable and are concentrated in a certain layer(s) on the radial path. PMID:10938811

Barrowclough, D E; Peterson, C A; Steudle, E

2000-03-01

381

Band Broadening in Micellar Liquid Chromatography  

Microsoft Academic Search

The effect of temperature on efficiency in micellar liquid chromatography (MLC) has been investigated using an SDS micellar mobile phase and a C18 stationary phase. Application of the Knox equation to plate count data yielded crucial information about band broadening in MLC. The improvement in chromatographic efficiency with temperature is due to a decrease in both the A (flow anisotropy)

Barry K. Lavine; Sumar Hendayana

1996-01-01

382

The Glueball Candidate ?(1440) as ? Radial Excitation  

NASA Astrophysics Data System (ADS)

The Particle Data Group decided to split the ?(1440) into two states, called ?L and ?H. The ?(1295) and the ?H are supposed to be the radial excitations of the ? and ?', respectively. The ?L state cannot be accomodated in a quark model; it cannot be a qbar {q} state, however, it might be a glueball. In this contribution it is shown that that the ?(1295) does not have the properties which must be expected for a radially excited state. The splitting of the ?(1440) is traced to a node in the wave function of a radial excitation. Hence the two peaks, ?L and ?H, originate from one resonance which is interpreted here as first radial excitation of the ?.

Klempt, Eberhard

2005-04-01

383

Radial construction of an arterial wall  

PubMed Central

SUMMARY Some of the most serious diseases involve altered size and structure of the arterial wall. Elucidating how arterial walls are built could aid understanding of these diseases, but little is known about how concentric layers of muscle cells and the outer adventitial layer are assembled and patterned around endothelial tubes. Using histochemical, clonal, and genetic analysis in mice, here we show that the pulmonary artery wall is constructed radially, from the inside out, by two separate but coordinated processes. One is sequential induction of successive cell layers from surrounding mesenchyme. The other is controlled invasion of outer layers by inner layer cells through developmentally-regulated cell reorientation and radial migration. We propose that a radial signal gradient controls these processes and provide evidence that PDGF-B and at least one other signal contribute. Modulation of such radial signaling pathways may underlie vessel-specific differences and pathological changes in arterial wall size and structure.

Greif, Daniel M.; Kumar, Maya; Lighthouse, Janet K.; Hum, Justine; An, Andrew; Ding, Ling; Red-Horse, Kristy; Espinoza, F. Hernan; Olson, Lorin; Offermanns, Stefan; Krasnow, Mark A.

2012-01-01

384

Wavelets, Fractals, and Radial Basis Functions.  

National Technical Information Service (NTIS)

Wavelets and radial basis functions (RBFs) lead to two distinct ways of representing signals in terms of shifted basis functions. RBFs, unlike wavelets, are nonlocal and do not involve any scaling, which makes them applicable to nonuniform grids. Despite ...

T. Blu M. Unser

2005-01-01

385

Computational Experience with Radial Basis Function Networks.  

National Technical Information Service (NTIS)

The report discusses the use of Radial Basis Functions for use in neural networks for hand-printed character recognition. The results are expected to apply to other applications of neural networks for classifying input patterns.

J. L. Blue

1993-01-01

386

Meshless Galerkin methods using radial basis functions  

Microsoft Academic Search

We combine the theory of radial basis functions with the field of Galerkin methods to solve partial differential equations. After a general description of the method we show convergence and derive error estimates for smooth problems in arbitrary dimensions.

Holger Wendland

1999-01-01

387

HD9446 radial velocity curve (Hebrard+, 2010)  

NASA Astrophysics Data System (ADS)

The table presents the SOPHIE measurements of HD9446. The three columns are respectively the Barycentric Julian Day of the observations, the radial velocity (in km/s) and its uncertainty (in km/s). (1 data file).

Hebrard, G.; Bonfils, X.; Segransan, D.; Moutou, C.; Delfosse, X.; Bouchy, F.; Boisse, I.; Arnold, L.; Desort, M.; Diaz, R. F.; Eggenberger, A.; Ehrenreich, D.; Forveille, T.; Lagrange, A.-M.; Lovis, C.; Pepe, F.; Perrier, C.; Pont, F.; Queloz, D.; Santos, N. C.; Udry, S.; Vidal-Madjar, A.

2010-03-01

388

Radial Force Characteristics of Switched Reluctance Machine.  

National Technical Information Service (NTIS)

The operation of a switched reluctance machine with eccentric rotor position creates asymmetrical airgap flux distributions and results in unbalanced magnetic pull. This paper comprehensively investigates the static and dynamic radial force characteristic...

N. R. Garrigan A. Storace W. L. Soong T. A. Lipo C. M. Stephens

1999-01-01

389

Investigation of contrast sensitivity following radial keratotomy.  

PubMed

Radial keratotomy is a surgical procedure for the correction of myopia in which the cornea is flattened by partial-thickness radial incisions. While postoperative visual acuity is usually good, measurements of acuity are of only limited value and do not describe visual performance for a variety of spatial frequencies and contrasts. In the present study, the effect of radial keratotomy on the contrast-sensitivity function was examined. Six spatial frequencies were tested (0.5, 1.0, 3.0, 6.0, 11.4, and 22.8 cycles/degree) using the Nicolet CS 2000 with patients wearing corrective lenses. The results revealed that, at least for the conditions tested, radial keratotomy does not produce a statistically significant decline in contrast sensitivity. PMID:3631835

Trick, L R; Hartstein, J

1987-07-01

390

Milky Way Cepheids radial velocities (Storm+, 2011)  

NASA Astrophysics Data System (ADS)

Repeated high precision radial velocity measurements for 14 galactic Cepheids obtained with the STELLA telescope and echelle spectrograph are presented together with the associated time stamps. From these data radial velocity curves with good phase coverage can be established. The Cepheids observed are: V496 Aql, TT Aql, VZ Cyg, {zeta} Gem, X Pup, AQ Pup, BN Pup, LS Pup, VZ Pup, X Sgr, Y Sgr, BB Sgr, XX Sgr, YZ Sgr. (2 data files).

Storm, J.; Gieren, W.; Fouque, P.; Barnes, T. G.; Pietrzynski, G.; Nardetto, N.; Weber, M.; Granzer, T.; Strassmeier, K. G.

2011-10-01

391

Comparison of Radial Basis Function Interpolants  

Microsoft Academic Search

This paper compares radial basis function interpolants on differentspaces. The spaces are generated by other radial basis functions,and comparison is done via an explicit representation of the norm ofthe error functional. The results pose some new questions for furtherresearch.x1. IntroductionWe consider interpolation of real-valued functions f defined on a set\\\\Omega` IRd; d 1. These functions are evaluated on a set

Robert Schaback

1995-01-01

392

Fractures of the radial head and neck.  

PubMed

The majority of simple fractures of the radial head are stable, even when displaced 2 mm. Articular fragmentation and comminution can be seen in stable fracture patterns and are not absolute indications for operative treatment. Preservation and/or restoration of radiocapitellar contact is critical to coronal plane and longitudinal stability of the elbow and forearm. Partial and complete articular fractures of the radial head should be differentiated. Important fracture characteristics impacting treatment include fragment number, fragment size (percentage of articular disc), fragment comminution, fragment stability, displacement and corresponding block to motion, osteopenia, articular impaction, radiocapitellar malalignment, and radial neck and metaphyseal comminution and/or bone loss. Open reduction and internal fixation of displaced radial head fractures should only be attempted when anatomic reduction, restoration of articular congruity, and initiation of early motion can be achieved. If these goals are not obtainable, open reduction and internal fixation may lead to early fixation failure, nonunion, and loss of elbow and forearm motion and stability. Radial head replacement is preferred for displaced radial head fractures with more than three fragments, unstable partial articular fractures in which stable fixation cannot be achieved, and fractures occurring in association with complex elbow injury patterns if stable fixation cannot be ensured. PMID:23467871

Ruchelsman, David E; Christoforou, Dimitrios; Jupiter, Jesse B

2013-03-01

393

Articulated module flow guide system  

SciTech Connect

A system is disclosed for promoting selective shell-side flow distribution between and providing structural support for modular straight tube bundles in a heat exchanger or the like, wherein a plurality of flow guides, each of which includes three axi-symmetrically-located radial panels, are connected along their outer radial edges to form a polygonal array establishing mutually shared partitions between modular tube bundles. Various flow guide configurations permit gaps in the mutually shared partitions to promote uniform shell-side communication between the modules, and accommodate individual tube bundle support grids in assembled relation with the flow guides. 4 figs.

Van Hagan, T.H.; Tanner, D.E.

1980-07-15

394

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.

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

2007-01-01

395

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

396

RIT pre-shipment check-out. Test report. [Radial inflow turbine  

SciTech Connect

The radial inflow turbine (RIT) unit was successfully air-run up to 26,000 rpm under no-load to check unit and system operation prior to shipment to Terry Corporation. Results were all nominal; no anomalies were uncovered. Recommendations are included which deal with minimum shaft loading during idle and the avoidance of condensate in the flow path.

Not Available

1982-09-02

397

A Novel Method for Optimal Distributed Generator Placement in Radial Distribution Systems  

Microsoft Academic Search

Optimal placement of distributed generators is essential, as inappropriate placement may increase the system losses. This article proposes a novel methodology for finding the optimal size and location for installation of Distributed Generators (DGs) so as to minimize total power losses in radial distribution systems. Distribution load flow is used to find the power loss in the system. The Proposed

Sri K. Nagaraju; S. Sivanagaraju; T. Ramana; S. Satyanarayana; P. V. Prasad

2011-01-01

398

Determining the impact of distributed generation on power systems. I. Radial distribution systems  

Microsoft Academic Search

Distributed generation (DG) has much potential to improve distribution system performance and it should be encouraged. However, distribution system designs and operating practices are normally based on radial power flows and this creates a special challenge to the successful introduction of distributed generation. This paper has described a few of the issues that must be considered to insure that DG

Philip P. Barker; Robert W. de Mello

2000-01-01

399

A physical based methodology to extrapolate performance maps of radial turbines  

Microsoft Academic Search

This paper details a physical based methodology to perform an extrapolation of the radial turbine performance maps, both mass flow characteristics and the efficiency curve. This method takes into account a narrow range of experimental data, which is usually the data available when such turbines are part of a turbocharger. Therefore, the extrapolation methodology is especially useful when data from

F. Payri; J. R. Serrano; P. Fajardo; M. A. Reyes-Belmonte; R. Gozalbo-Belles

400

Use of interval arithmetic to incorporate the uncertainty of load demand for radial distribution system analysis  

Microsoft Academic Search

In this letter, the probabilistic distribution-based interval arithmetic approach is used to incorporate uncertainty in load demand. The variation of load is represented as Gaussian distribution function. It is suggested that the proposed power flow could be useful for planning and expansion planning of radial distribution systems.

A. Chaturvedi; K. Prasad; R. Ranjan

2006-01-01

401

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

402

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

403

Sample concentration using optical chromatography  

NASA Astrophysics Data System (ADS)

Optical chromatography is a technique for the separation of particles that capitalizes on the balance between optic and fluidic forces. When microscopic particles in a fluid flow encounter a laser beam propagating in the opposite direction, they are trapped axially along the beam. They are then optically pushed upstream from the laser focal point to rest at a point where the optic and fluidic forces on the particle balance. Because optical and fluid forces are sensitive to differences in the physical and chemical properties of a particle, both coarse and fine separations are possible. We describe how an optical chromatography beam directed into a tailored flow environment, has been adapted to operate as an optical filter for the concentration / bioenrichment of colloidal and biological samples. In this work, the demonstrated ability to concentrate spores of the biowarfare agent, Bacillus anthracis, may have significant impact in the biodefense arena. Application of these techniques and further design of fluidic and optical environments will allow for more specific identification, concentration and separation of many more microscopic particle and biological suspensions.

Hart, Sean J.; Terray, Alex; Arnold, Jonathan; Leski, Tomasz A.

2007-03-01

404

Radial spoke proteins of Chlamydomonas flagella  

PubMed Central

Summary The radial spoke is a ubiquitous component of ‘9+2’ cilia and flagella, and plays an essential role in the control of dynein arm activity by relaying signals from the central pair of microtubules to the arms. The Chlamydomonas reinhardtii radial spoke contains at least 23 proteins, only 8 of which have been characterized at the molecular level. Here, we use mass spectrometry to identify 10 additional radial spoke proteins. Many of the newly identified proteins in the spoke stalk are predicted to contain domains associated with signal transduction, including Ca2+-, AKAP- and nucleotide-binding domains. This suggests that the spoke stalk is both a scaffold for signaling molecules and itself a transducer of signals. Moreover, in addition to the recently described HSP40 family member, a second spoke stalk protein is predicted to be a molecular chaperone, implying that there is a sophisticated mechanism for the assembly of this large complex. Among the 18 spoke proteins identified to date, at least 12 have apparent homologs in humans, indicating that the radial spoke has been conserved throughout evolution. The human genes encoding these proteins are candidates for causing primary ciliary dyskinesia, a severe inherited disease involving missing or defective axonemal structures, including the radial spokes.

Yang, Pinfen; Diener, Dennis R.; Yang, Chun; Kohno, Takahiro; Pazour, Gregory J.; Dienes, Jennifer M.; Agrin, Nathan S.; King, Stephen M.; Sale, Winfield S.; Kamiya, Ritsu; Rosenbaum, Joel L.; Witman, George B.

2007-01-01

405

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

406

Radial anisotropy along the Tethyan margin  

NASA Astrophysics Data System (ADS)

We estimate radial anisotropy along the Tethyan margin by jointly fitting regional S and Love waveform trains and fundamental-mode Love-wave group velocities. About 3600 wave trains with S and Love waves and 5700 Love-wave group velocity dispersion curves are jointly inverted for SH-velocity perturbations from a pre-existing, 3-D SV-velocity model. These perturbations are predominantly positive (SH faster than SV) and consistent with PREM, but our model also shows significant lateral variation in radial anisotropy that appears to be correlated with tectonic environment. SH waves travel faster than SV wave beneath backarc basins, oceans and orogenic belts such as the Tyrrhenian and Pannonian basins, the Ionian Sea, the Alps, the Apennines, the Dinarides and the Caucasus. The Algero-Provençal basin, however, is underlain by faster SV velocity. Faster SV velocity of radial anisotropy is also detected within cratons such as the East European platform and the Arabian shield. Beneath hotspots we detect a change in radial anisotropic polarity with depth, which may be caused by transition between the lattice-preferred orientation from horizontal deformation in the asthenosphere and the shape-preferred orientation from vertically oriented melt channels in the lithosphere. We also find significant portion of radial anisotropy within subducting slabs depends on the slab's dip angle.

Chang, Sung-Joon; van der Lee, Suzan; Matzel, Eric; Bedle, Heather

2010-08-01

407

Radial glia: multi-purpose cells for vertebrate brain development  

Microsoft Academic Search

Radial glia are specialized cells in the developing nervous system of all vertebrates, and are characterized by long radial processes. These processes facilitate the best known function of radial glia: guiding the radial migration of newborn neurons from the ventricular zone to the mantle regions. Recent data indicate further important roles for these cells as ubiquitous precursors that generate neurons

Kenneth Campbell; Magdalena Götz

2002-01-01

408

Radial Force Control of a Novel Hybrid Pole BLSRM  

Microsoft Academic Search

This paper presents a novel hybrid pole BLSRM (Bearingless Switched Reluctance Motor) and its radial force control scheme. The proposed hybrid pole BLSRM has separated radial force poles and rotating torque poles. According to the FEM analysis, the proposed BLSRM has an excellent linear characteristic of radial force and controllability that is independent from the torque current. The radial force

Huijun Wang; Dong-Hee Lee; Jin-Woo Ahn

2009-01-01

409

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

410

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.

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

2012-01-01

411

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

412

Ion Exchange Chromatography  

NSDL National Science Digital Library

This website contains an ion chromatography simulator that can be run online or can be downloaded. The simulator focuses on separations of proteins using Ion Chromatography. Also included is linked reference information, an example of a homework assignment using the simulator, and some information on protein structures.

2011-05-23

413

Ten-year Echo-Doppler evaluation of forearm circulation following radial artery removal for coronary artery bypass grafting  

Microsoft Academic Search

Objective: To investigate the chronic consequences of radial artery removal for coronary artery bypass surgery on the forearm circulation. Methods: Thirty-ninepatients submitted to radial artery removal for coronaryartery bypass were submitted to serial Echo-Doppler evaluationof the flow and morphology of the forearm arteries until 10 years follow-up. Results: The peak systolic velocity of the ulnar artery of the operated side

Mario Gaudino; Franco Glieca; Nicola Luciani; Gianfranca Losasso; Paolo Tondi; Michele Serricchio; Paolo Pola; Gianfederico Possati

2010-01-01

414

Ten-year Echo-Doppler evaluation of forearm circulation following radial artery removal for coronary artery bypass grafting  

Microsoft Academic Search

Objective: To investigate the chronic consequences of radial artery removal for coronary artery bypass surgery on the forearm circulation. Methods: Thirty-nine patients submitted to radial artery removal for coronary artery bypass were submitted to serial Echo-Doppler evaluation of the flow and morphology of the forearm arteries until 10 years follow-up. Results: The peak systolic velocity of the ulnar artery of

Mario Gaudino; Franco Glieca; Nicola Luciani; Gianfranca Losasso; Paolo Tondi; Michele Serricchio; Paolo Pola; Gianfederico Possati

2006-01-01

415

Cloaking and magnifying using radial anisotropy  

NASA Astrophysics Data System (ADS)

This paper studies the electrostatic responses of a polarly radially anisotropic cylinder and a spherically radially anisotropic sphere. For both geometries, the permittivity components differ from each other in the radial and tangential directions. We show that choosing the ratio between these components in a certain way, these rather simple structures can be used in cloaking dielectric inclusions with arbitrary permittivity and shape in the quasi-static limit. For an ideal cloak, the contrast between the permittivity components has to tend to infinity. However, only positive permittivity values are required and a notable cloaking effect can already be observed with relatively moderate permittivity contrasts. Furthermore, we show that the polarly anisotropic cylindrical shell has a complementary capability of magnifying the response of an inner cylinder.

Kettunen, Henrik; Wallén, Henrik; Sihvola, Ari

2013-07-01

416

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

417

Dispersion-free radial transmission lines  

SciTech Connect

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

418

Manufacturing of Precision Forgings by Radial Forging  

NASA Astrophysics Data System (ADS)

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.; Hofer, F.

2011-01-01

419

Plasma signatures on radially resolved line emission  

NASA Astrophysics Data System (ADS)

In the last few years, various intriguing emission profiles have been observed in time-gated, radially resolved measurements of K-shell line emission from imploding and stagnating Z-pinch plasmas. The radially resolved lines have appeared as hollow or closed ovals whose extents in the spatial and (Doppler-shifted) wavelength dimensions record the plasma radius and velocity, respectively. Optically thick lines can lead to asymmetries in both spatial and wavelength dimensions, such as limb darkening and preferential absorption of velocity-matched wavelengths. We present the results of a comprehensive investigation of density, temperature, and velocity gradients and their effects on radially resolved emission lines, listing the combinations of plasma conditions that can give rise to signature emission features. Sandia is a multi-program 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.

Hansen, S. B.; Jones, B.; Rochau, G. A.; Bailey, J. E.; Ampleford, D. J.; Jennings, C. A.; Coverdale, C. A.; Cuneo, M. E.; Maron, Y.; Fisher, V.; Bernshtam, V.; Starobinets, A.; Weingarten, L.

2009-11-01

420

Precision Near-Infrared Radial Velocities  

NASA Astrophysics Data System (ADS)

We have built a single gas absorption cell for precision spectroscopic radial velocity measurements in the near-infrared. We are currently carrying out a survey with the CSHELL spectrograph at the NASA InfraRed Telescope Facility to detect exoplanets around red, low mass, and young stars. We discuss the current status of our survey, with the aim of 20 m/s long-term photon-noise limited radial velocity precision at 2.3 microns. We present the design of a near-infrared fiber scrambler with first light in May 2012 with CSHELL at IRTF. The fiber scrambler makes use of non-circular core fibers to stabilize the illumination of the slit and echelle grating against changes in seeing, focus, guiding and other sources of systematic radial velocity noise, complementing the wavelength calibration of a gas cell.

Plavchan, Peter; NIRRVs

2012-10-01

421

Precision Near-Infrared Radial Velocities  

NASA Astrophysics Data System (ADS)

We have built a single gas absorption cell for precision spectroscopic radial velocity measurements in the near-infrared. We will present radial velocity time-series from a 2.3 micron pilot survey with the CSHELL spectrograph at the NASA InfraRed Telescope Facility to detect exoplanets around red, low mass, and young stars. We will present first light data at 1.6 microns from a near-infrared fiber scrambler used in tandem with our gas cell and CSHELL at IRTF. The fiber scrambler makes use of non-circular core fibers to stabilize the illumination of the slit and echelle grating against changes in seeing, focus, guiding and other sources of systematic radial velocity noise, complementing the wavelength calibration of a gas cell.

Plavchan, Peter; Anglada-Escude, G.; White, R.; Gao, P.; Davison, C.; Mills, S.; Beichman, C.; Brinkworth, C.; Johnson, J. A.; Bottom, M.; Ciardi, D.; Wallace, K.; Mennesson, B.; von Braun, K.; Vasisht, G.; Prato, L.; Kane, S.; Tanner, A.; Walp, B.; Crawford, S.

2013-10-01

422

Radial force balance within Jupiter's dayside magnetosphere  

NASA Astrophysics Data System (ADS)

A local field stress technique, developed previously in a study of the Saturnian magnetosphere, is introduced to the problem of determining the radial force balance characteristics of Jupiter's magnetosphere. The authors begin by estimating the near-equatorial, radial magnetic force densities using the data obtained by Voyager 1 principally on the dayside (inbound) portion of its trajectory (7.4 ? R(Rj) ? 42). Using the low-energy charged particle data (?30 keV) and other published data they then explore ways in which the field forces might be balanced. Comparing present results with the results of a previous study, the authors note that contrary to common expectations, Saturn rather than Jupiter is unique in having the corotation centrifugal forces dominate over other sources of radial particle force in some regions of the middle (ring current) equatorial magnetosphere.

Mauk, B. H.; Krimigis, S. M.

1987-09-01

423

Mapping radial features in Saturn's rings  

NASA Astrophysics Data System (ADS)

We have carried out a comprehensive survey of the best Cassini ISS data of Saturn's main rings for the purpose of cataloguing all observed spiral density waves, spiral bending waves, and other radial and quasi-radial ring structure. Our survey has revealed a number of new features, including the first known resonant waves raised by Enceladus and Hyperion, thus increasing the number of points at which the local surface density and viscosity of the rings can be measured (cf. Tiscareno et al. 2007, Icarus). We also catalogue several wave-like features whose cause is unknown. Although images of the rings taken by the Imaging Science Subsystem (ISS) are not nominally as high-resolution as the best stellar and radio occultations, they are capable of superior signal-to-noise because of the co-adding inherent in converting a 2-D image into a 1-D "radial scan." In this common technique, as many as a thousand pixels at a given radial distance from Saturn are combined to produce a single characteristic brightness for each radial location. This process suppresses local structure, azimuthal structure, and random noise, all of which commonly decrease the sensitivity of high-resolution occultations, and causes ISS to be the optimal Cassini instrument for detecting a certain class of low-amplitude features. Finally, we employ wavelet techniques (cf. Tiscareno et al. 2007, Icarus) to elucidate subtle periodic and quasi-periodic features in the radial scan data. We will present our results in the context of a ranking of known perturbations in the rings by their resonant torque (updating Lissauer and Cuzzi 1982, AJ). We will identify the strongest expected perturbations that do not appear, and discuss whether the absence is likely to reflect a real limit of ring responsiveness, or (as with previous observations) to reflect sensitivity limits.

Tiscareno, Matthew S.; Harris, B. E.

2013-10-01

424

A new method for characterizing axis of rotation radial error motion: Part 1. Two-dimensional radial error motion theory  

Microsoft Academic Search

In the current standards of spindle metrology, the fundamental component of radial probe measurement is considered radial throw (eccentricity) of the installed test artifact and the fundamental radial error motion is treated as non-existent. The goals of this paper are: (1) to make evident the fact that fundamental radial error motion can actually exist; (2) to present a new two-dimensional

Xiaodong Lu; Arash Jamalian

2011-01-01

425

Electrostatic model of radial pn junction nanowires  

NASA Astrophysics Data System (ADS)

Poisson's equation is solved for a radial pn junction nanowire (NW) with surface depletion. This resulted in a model capable of giving radial energy band and electric field profiles for any arbitrary core/shell doping density, core/shell dimensions, and surface state density. Specific cases were analyzed to extract pertinent underlying physics, while the relationship between NW specifications and the depletion of the NW were examined to optimize the built-in potential across the junction. Additionally, the model results were compared with experimental results in literature to good agreement. Finally, an optimum device design is proposed to satisfy material, optical, and electrostatic constraints in high efficiency NW solar cells.

Chia, A. C. E.; LaPierre, R. R.

2013-08-01

426

A rare complication of radial artery catheterization.  

PubMed

An arterial pseudoaneurysm is a cavity which does not consist of three layers of arterial wall and is generally seen at femoral and radial artery sites due to bone fractures, arterial injuries and iatrogenic reasons such as catheterization. The treatment choice may be either surgical or conservative. Patients with pseudoaneurysm should be carefully followed and the treatment choice should be immediately decided to avoid possible complications. We report a case of pseudoaneurysm formation in the radial artery that occurred one week after arterial catheterization for coronary angiography. The treatment choice for this patient was surgical and he was discharged without any complications. PMID:21652670

Inan, Mustafa Bahadir; Acikgoz, Burak; Yazicioglu, Levent; Kaya, Bulent; Ozyurda, Umit

427

Radial characterisation of the helium plasma produced by the axial injection torch (TIA) at atmospheric pressure  

NASA Astrophysics Data System (ADS)

This work presents the radial characterisation of a helium plasma produced by the “Torch à Injection Axiale” by means of the determination of the electron density and electron temperature. Through the Abel inversion technique on the experimental data, the radial distribution of absolute intensity along the flame is obtained, from which we can study the spatial distribution of the excited states as a function of the helium flow rate and the absorbed HF power. Finally, using a collisional-radiative model for helium at atmospheric pressure, the electronic density and electronic temperature at each point in the flame are obtained.

Álvarez, R.; Rodero, A.; Quintero, M. C.

2000-03-01

428

The structure of tip clearance flow in axial flow compressors  

Microsoft Academic Search

Detailed measurements of the flow field in the tip region of an axial flow compressor rotor were carried out using a rotating five-hole probe. The axial, tangential, and radial components of relative velocity, as well as the static and stagnation pressures, were obtained at two axial locations, one at the rotor trailing edge, the other downstream of the rotor. The

B. Lakshminarayana; M. Zaccaria; B. Marathe

1995-01-01

429

Investigation on centrifugal impeller in an axial-radial combined compressor with inlet distortion  

NASA Astrophysics Data System (ADS)

Assembling an axial rotor and a stator at centrifugal compressor upstream to build an axial-radial combined compressor could achieve high pressure ratio and efficiency by appropriate size augment. Then upstream potential flow and wake effect appear at centrifugal impeller inlet. In this paper, the axial-radial compressor is unsteadily simulated by three-dimensional Reynolds averaged Navier-Stokes equations with uniform and circumferential distorted total pressure inlet condition to investigate upstream effect on radial rotor. The results show that span-wise nonuniform total pressure distribution is generated and radial and circumferential combined distortion is formed at centrifugal rotor inlet. The upstream stator wake deflects to rotor rotation direction and decreases with blade span increases. Circumferential distortion causes different separated flow formations at different pitch positions. The tip leakage vortex is suppressed in centrifugal blade passages. Under distorted inlet condition, flow direction of centrifugal impeller leading edge upstream varies evidently near hub and shroud but varies slightly at mid-span. In addition, compressor stage inlet distortion produces remarkable effect on blade loading of centrifugal blade both along chordwise and pitchwise.

Li, Du; Yang, Ce; Zhao, Ben; Zhou, Mi; Qi, Mingxu; Zhang, Jizhong

2011-12-01

430

Evaluation of Susceptibility of Gram-Positive and Negative Bacteria to Human Defensins by Using Radial Diffusion Assay  

Microsoft Academic Search

Defensinsaresmallcationicbactericidalpeptidespresentabundantlyinthegranulesofpolymorphonuclear neutrophils (PMNs). Human PMNs contain four defensins termed HNP-1 to HNP-4. We used a new assay system in agar plates, the radial diffusion assay, to evaluate the effects of human defensins against gram- positive and -negative bacteria. A crude mixture of HNP-1, -2, and -3 (crude HNPs) was purified from human PMN extracts by reversed-phase high-pressure liquid chromatography (RP-HPLC).

HIROMU TAKEMURA; MITSUO KAKU; SHIGERU KOHNO; YOICHI HIRAKATA; HIRONORI TANAKA; RYOJI YOSHIDA; KAZUNORI TOMONO; HIRONOBU KOGA; AKIHIRO WADA; TOSHIYA HIRAYAMA; ANDSHIMERU KAMIHIRA

1996-01-01

431

RADIAL BASIS FUNCTION EQUALIZATION USING COMPETITIVE LEARNING  

Microsoft Academic Search

In this paper the problem of equalization of multiple quadrature amplitude modulated signals, using a radial basis function (RBF) neural network, is studied. Because the equalizer performance is directly related to the estimations of the RBF centres, different competitive learning algorithms for the RBF centres are presented. A new competitive algorithm is introduced, the rival penalized competitive learning, which rewards

CORINA BOTOCA; GEORGETA BUDURA

432

Optimal capacitor placement on radial distribution systems  

Microsoft Academic Search

Capacitor placement problem on radial distribution systems is formulated and a solution algorithm is proposed. The location, type, and size of capacitors, voltage constraints, and load variations are considered in the problem. The objective of capacitor placement is peak power and energy loss reduction by raking into account the cost of capacitors. The problem is formulated as a mixed integer

M. E. Baran; F. F. Wu

1989-01-01

433

Extended foil capacitor with radially spoked electrodes  

DOEpatents

An extended foil capacitor has a conductive disk electrically connected in oncrushing contact to the extended foil. A conductive paste is placed through spaces between radial spokes on the disk to electrically and mechanically connect the extended foil to the disk.

Foster, James C. (Indian Shores, FL)

1990-01-01

434

Calibration of Cameras with Radially Symmetric Distortion  

Microsoft Academic Search

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

Jean-philippe Tardif; Peter F. Sturm; Martin Trudeau; Sébastien Roy

2009-01-01

435

The Carina Project. IV. Radial Velocity Distribution  

Microsoft Academic Search

We present new and accurate radial velocity (RV) measurements of luminous stars of all ages (old horizontal branch, intermediate-age red clump, and young blue plume, as well as red giants of a range of ages: 20.6 <= V <= 22 ) in the Carina dwarf spheroidal galaxy, based on low-resolution spectra collected with the FORS2 multiobject slit spectrograph at the

M. Fabrizio; M. Nonino; G. Bono; I. Ferraro; P. François; G. Iannicola; M. Monelli; F. Thévenin; P. B. Stetson; A. R. Walker; R. Buonanno; F. Caputo; C. E. Corsi; M. Dall'Ora; R. Gilmozzi; C. R. James; T. Merle; L. Pulone; M. Romaniello

2011-01-01

436

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

437

On unsymmetric collocation by radial basis functions  

Microsoft Academic Search

Solving partial differential equations by collocation with radial basis functions can be efficiently done by a technique first proposed by Kansa in 1990. It rewrites the problem as a generalized interpolation problem, and the solution is obtained by solving a (possibly large) linear system. The method has been used successfully in a variety of applications, but a proof of nonsingularity

Y. C. Hon; R. Schaback

2001-01-01

438

Extended foil capacitor with radially spoked electrodes  

DOEpatents

An extended foil capacitor has a conductive disk electrically connected in noncrushing contact to the extended foil. A conductive paste is placed through spaces between radial spokes on the disk to electrically and mechanically connect the extended foil to the disk.

Foster, J.C.

1989-04-20

439

Second Propagation in Radial Fan Casings.  

National Technical Information Service (NTIS)

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 expansi...

M. Bartenwerfer T. Gikadi

1985-01-01

440

Studies on freejets from radially lobed nozzles  

Microsoft Academic Search

The freejet characteristics of radially lobed nozzles were studied experimentally. Schlieren photographs of the freejets revealed that the lobes of the nozzles gave rise to alternate expansion-compression regions. For two of the lobed nozzles the potential core was reduced by a factor of three relative to the conical nozzle tested. The jet spread and the shear layer thickness of the

R. Ramesh Kumar; J. Kurian

1995-01-01

441

Extension of elution range in micellar electrokinetic capillary chromatography  

Microsoft Academic Search

The authors have successfully demonstrated one approach to extend elution range in micellar electrokinetic capillary chromatography (MECC). By silanating the surfaces of fused-silica capillaries with trimethylchlorosilane (TMCS) the authors lowered electroosmotic flow velocity and, more importantly, the net flow velocity of the micelle phase, thereby increasing elution range. This is accomplished at the expense of a loss in column efficiency

A. T. Balchunas; M. J. Sepaniak

1987-01-01

442

Radially oriented anthracene nanowire arrays: preparation, growth mechanism, and optical fluorescence  

NASA Astrophysics Data System (ADS)

Radially oriented anthracene nanowires and their self-assembled concentric ring arrays were prepared through a facial solvent-evaporation method. The successful growth of anthracene nanowires can be attributed to a combined mechanism of molecular self-assembly facilitated by strong ?-? intermolecular interactions together with evaporation-induced capillary flow and fingering instability. Their radial orientation is determined by the capillary flow; their shape (either straight or curved nanowires) is governed by the competition between the capillary and Marangoni convectional flows. The self-assembly of nanowires into large-scale concentric ring arrays can be interpreted in terms of the repeated slipping-and-sticking motions of the contact line. The high-quality crystalline anthracene nanowire arrays exhibit size-dependent fluorescence emission with high-degree anisotropy.Radially oriented anthracene nanowires and their self-assembled concentric ring arrays were prepared through a facial solvent-evaporation method. The successful growth of anthracene nanowires can be attributed to a combined mechanism of molecular self-assembly facilitated by strong ?-? intermolecular interactions together with evaporation-induced capillary flow and fingering instability. Their radial orientation is determined by the capillary flow; their shape (either straight or curved nanowires) is governed by the competition between the capillary and Marangoni convectional flows. The self-assembly of nanowires into large-scale concentric ring arrays can be interpreted in terms of the repeated slipping-and-sticking motions of the contact line. The high-quality crystalline anthracene nanowire arrays exhibit size-dependent fluorescence emission with high-degree anisotropy. Electronic supplementary information (ESI) available: Additional data. See DOI: 10.1039/c0nr01012j

Wu, Ji Hong; Xu, Tian Ze; Ang, Siau Gek; Xu, Qing-Hua; Xu, Guo Qin

2011-04-01

443

Radial Wave Crystals: Radially Periodic Structures from Anisotropic Metamaterials for Engineering Acoustic or Electromagnetic Waves  

NASA Astrophysics Data System (ADS)

We demonstrate that metamaterials with anisotropic properties can be used to develop a new class of periodic structures that has been named radial wave crystals. They can be sonic or photonic, and wave propagation along the radial directions is obtained through Bloch states like in usual sonic or photonic crystals. The band structure of the proposed structures can be tailored in a large amount to get exciting novel wave phenomena. For example, it is shown that acoustical cavities based on radial sonic crystals can be employed as passive devices for beam forming or dynamically orientated antennas for sound localization.

Torrent, Daniel; Sánchez-Dehesa, José

2009-08-01

444

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

445

Performance of new prototype packed columns for very high pressure liquid chromatography.  

PubMed

The reduced heights equivalent to a theoretical plate (HETP) of naphtho[2,3-a]pyrene were measured at room temperature on two sets of new prototype columns designed to be used in very high pressure liquid chromatography (VHPLC). The mobile phase used was pure acetonitrile. The columns are 50, 100, and 150 mm long. Those of the first set are 2.1 mm I.D., those of the second set, 3.0 mm I.D. The performance of these new columns were compared to those of the first generation of VHPLC columns, commercially available in 2.1 mm I.D. The prototype and commercial columns behave similarly at low reduced linear velocities (nu<5), when the heat effects are negligible. At high flow rates, the shorter prototype columns have a twice better efficiency and less steep C-branches than the commercial columns. In contrast, the C-branch of the 150 mm long prototype columns are slightly steeper than those of the commercial columns. The important contribution to the reduced HETP that is due to the heat effects at high flow rates can in part be accounted for by a band broadening model governed by a flow mechanism with the shortest prototype columns. The sole heat effects cannot, however, explain the mediocre reduced HETPs of the 2.1 and 3.0 I.D. 150 mm long prototype columns. It seems that radial heterogeneity of the flow rate of the long prototype columns is significantly larger than that of the short columns. The contribution of the packing heterogeneity adds up to that of the heat effects to yield a poor column efficiency when sub-2 microm are packed into thin, long column tubes. PMID:20060978

Gritti, Fabrice; Guiochon, Georges

2010-01-04

446

Special Report: Affinity Chromatography.  

ERIC Educational Resources Information Center

Describes the nature of affinity chromatography and its use in purifying enzymes, studying cell interactions, exploring hormone receptors, and other areas. The potential the technique may have in treating disease is also considered. (JN)

Parikh, Indu; Cuatrecasas, Pedro

1985-01-01

447

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.

448

Gas chromatography in space.  

PubMed

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. PMID:10399853

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

1999-05-28

449

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.

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

1996-01-01

450

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

451

Applications of Radial Basis Functions: Sobolev-Orthogonal Functions, Radial Basis Functions and Spectral Methods.  

National Technical Information Service (NTIS)

In this paper we consider an application of Sobolev-orthogonal functions and radial basis function to the numerical solution of partial differential equations. We develop the fundamentals of a spectral method, present examples via reaction-diffusion parti...

A. Iserles M. D. Buhmann S. P. Norsett

2001-01-01

452

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

453

Cross-Axis Synchronous Flow-Through Coil Planet Centrifuge Free of Rotary Seals for Preparative Countercurrent Chromatography. Part II. Studies on Phase Distribution and Partition Efficiency in Coaxial Coils  

Microsoft Academic Search

Potential capability of the apparatus in performing countercurrent chroma-tography has been examined with three different types of coiled columns, all coaxially mounted around the holder. In single-layer coils, typical solvent systems display characteristic hydrodynamic distribution which ensures a stable retention of the stationary phase against heavy sample loading in preparative separations. Direct observation of the hydrodynamic motion in the rotating

Yoichiro Ito

1987-01-01

454

Structural radial heterogeneity of a silica-based wide-bore monolithic column  

SciTech Connect

The radial distribution of the main characteristics (elution time and standard deviation) of the elution profiles of a flat injected band recorded at the exit of a monolithic column were determined. These distributions provide the radial distributions of the average mobile phase velocity, the elution time and the maximum height of the peak of an analyte, the column efficiency and the analyte concentration. The band profiles were measured at the exit of a 10-mm i.d., 100-mm long silica-based monolithic column. An on-column local electrochemical amperometric detector allowed the recording of the elution profiles at different spatial positions throughout the column cross-section. The local spatial distribution of the mobile phase velocity does not follow a piston-flow behavior but exhibits radial heterogeneity. The local efficiency near the wall is lower than that near the column center. The radial distribution of the maximum concentration of the peaks varies throughout the column exit section, partially due to the radial variations of the column efficiency. These results might explain the rather large value of the A term of the Van Deemter or the Knox equations reported previously for monolithic columns.

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

2008-01-01

455

Radial glia produce and align the ligand fibronectin during neuronal migration in the developing chick brain.  

PubMed

We demonstrated previously that alpha8beta1 integrin regulates the migration and survival of immature neurons during development of the chicken optic tectum; however, the potential extracellular ligand was unknown. We used immunohistochemistry to determine if several potential ligands (fibronectin, tenascin, vitronectin, and osteopontin) were expressed during neuronal migration along radial glia (RG). Fibronectin was localized in a pattern relevant to radial migration and survival of neurons; it was present before and during neuronal migration and appeared oriented along RG fibers by conventional fluorescence microscopy. Confocal microscopy confirmed that fibronectin was localized along RG cells during radial migration. It was more concentrated in some superficial laminae, which might support directional movement. Fibronectin was present after formation of definitive tectal laminae, but was diffuse and not aligned along RG, which persist. Flow cytometry analysis of dissociated optic tectum cells revealed that almost all RG were positive for fibronectin. Short-term cell culture experiments using an exocytosis inhibitor revealed that fibronectin accumulated in most RG cells. Thus, fibronectin is produced by RG and is aligned along their surfaces before and during migration. Fibronectin, therefore, is a potential ligand for general radial neuronal migration in the chick optic tectum. Its predominant source appears to be RG, in contrast with developing mammalian cortex, where fibronectin was not found in a pattern that could guide widespread radial migration and where neurons are the predominant producers of fibronectin during migration. PMID:14681936

Stettler, Erin M; Galileo, Deni S

2004-01-12

456

Hydraulic analysis of a radial collector well for riverbank filtration near Nakdong River, South Korea  

NASA Astrophysics Data System (ADS)

A radial collector well is used for the extraction of a large amount of groundwater without causing a deep drawdown at the well's center, and it is appropriate for the supply of municipal water through riverbank filtration (RBF). Flow path changes caused by water extraction through a radial collector well were simulated to estimate the amount of river water induction at a RBF site associated with Nakdong River in South Korea. The structure of the screened horizontal arms of a radial collector well was examined with respect to effective riverbank filtration. The relative ratio of the river water induced to the radial collector well compared to the total groundwater extraction was estimated to be 27-52%. The amount of induced river water varies with the distance of a horizontal arm from the river, indicating that the location and structure of the collector well is significant for RBF. In all simulation cases, the maximum drawdown of the groundwater level near the collector well was 2.1 m, which is not significant considering the substantial pumping rate at the study site. It was concluded that RBF radial collector wells can be used at the study site for a sustainable water supply.

Lee, Eunhee; Hyun, Yunjung; Lee, Kang-Kun; Shin, Jiyoun

2012-05-01

457

Radial anisotropy in the crust of SE Tibet and SW China from ambient noise interferometry  

NASA Astrophysics Data System (ADS)

We use Rayleigh and Love wave Green’s functions estimated from ambient seismic noise to study crustal structure and radial anisotropy in the tectonically complex and seismically active region west of Sichuan Basin and around the Eastern Himalaya Syntaxis. Seismic noise records are from 372 stations of 3 seismic arrays: MIT and Lehigh arrays (Nov 2003- Aug 2004), and CEA array (Jan 2007 - Dec 2007), with average inter-station spacing from 10km to 70 km. The 3-D variations of shear wave speed inferred from Rayleigh and Love waves are generally consistent. In agreement with previous studies, low velocity zones are ubiquitous in the mid-lower crust, with substantial variations both laterally and vertically. Discrepancies between 3-D shear velocity from either Rayleigh (V_SV) or Love (V_SH) waves are examined both in view of non-uniqueness of tomographic solutions and radial anisotropy. Low shear wave speed and radial anisotropy with V_SH > V_SV are most prominent in mid-lower crust in the Lhasa block, the southern Songpan-Ganze block and the western part of Yangtze block. Furthermore, in the middle crust we infer a (weak) negative correlation between V_SV and radial anisotropy, with low V_SV and strong radial anisotropy (V_SH > V_SV). Our results are consistent with flow-induced horizontal mica fabric in crustal zones of relatively low mechanical strength.

Huang, H.; Li, Y.; Yao, H.; van der Hilst, R. D.; Liu, Q.; Chen, J.

2010-12-01

458

Aerodynamically induced radial forces in a centrifugal gas compressor. Part 1: Experimental measurement  

SciTech Connect

Net radial loading arising from asymmetric pressure fields in the volutes of centrifugal pumps during off-design operation is well known and has been studied extensively. In order to achieve a marked improvement in overall efficiency in centrifugal gas compressors, vaneless volute diffusers are matched to specific impellers to yield improved performance over a wide application envelope. As observed in centrifugal pumps, nonuniform pressure distributions that develop during operation above and below the design flow create static radial loads on the rotor. In order to characterize these radial forces, a novel experimental measurement and post-processing technique is employed that yields both the magnitude and direction of the load by measuring the shaft centerline locus in the tilt-pad bearings. The method is applicable to any turbomachinery operating on fluid film radial bearings equipped with proximity probes. The forces are found to be a maximum near surge and increase with higher pressures and speeds. The results are nondimensionalized, allowing the radial loading for different operating conditions to be predicted.

Moore, J.J.; Flathers, M.B. [Solar Turbines Inc., San Diego, CA (United States)

1998-04-01

459

The floating radial head prosthesis for comminuted radial head fractures: a multicentric study.  

PubMed

We report our experience with the floating radial head prosthesis of Judet for comminuted fractures of the radial head. We present the results in 15 patients with a mean follow-up of 25.2 months. Thirteen prostheses were inserted for acute Mason III fractures of the radial head, and 2 were inserted for chronic problems after radial head fracture. According to the Mayo Elbow Performance Index there were 7 excellent, 3 good, 1 fair and 2 poor results in the group with acute injuries. In this group, one prosthesis was removed after 8 months for severely decreased elbow function. In the group with chronic problems, there were 2 fair results. There were no dislocations or prosthesis fractures. None of the prostheses showed signs of loosening. Three patients in the acute group developed wrist pain, and in one patient in the chronic group, preexisting wrist pain disappeared after insertion of the radial head prosthesis. Our short-term results suggest that the floating radial head prosthesis is a suitable solution for early or delayed treatment of Mason type III fr