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1

THE THEORY OF URANIUM ENRICHMENT BY THE GAS CENTRIFUGE  

SciTech Connect

Onsager's analysis of the hydrodynamics of fluid circulation in the boundary layer on the rotor wall of a gas centrifuge is reviewed. The description of the flow in the boundary layers on the top and bottom end caps due to Carrier and Maslen is summarized. The method developed by Wood and Morton of coupling the flow models in the rotor wall and end cap boundary layers to complete the hydrodynamic analysis of the centrifuge is presented. Mechanical and thermal methods of driving the internal gas circulation are described. The isotope enrichment which results from the superposition of the elementary separation effect due to the centrifugal field in the gas and its internal circulation is analyzed by the Onsager-Cohen theory. The performance function representing the optimized separative power of a centrifuge as a function of throughput and cut is calculated for several simplified internal flow models. The use of asymmetric ideal cascades to exploit the distinctive features of centrifuge performance functions is illustrated.

Olander, Donald R.

1981-03-01

2

Gas Centrifuges and Nuclear Proliferation  

SciTech Connect

Gas centrifuges have been an ideal enrichment method for a wide variety of countries. Many countries have built gas centrifuges to make enriched uranium for peaceful nuclear purposes. Other countries have secretly sought centrifuges to make highly enriched uranium for nuclear weapons. In more recent times, several countries have secretly sought or built gas centrifuges in regions of tension. The main countries that have been of interest in the last two decades have been Pakistan, Iraq, Iran, and North Korea. Currently, most attention is focused on Iran, Pakistan, and North Korea. These states did not have the indigenous abilities to make gas centrifuges, focusing instead on illicit and questionable foreign procurement. The presentation covered the following main sections: Spread of centrifuges through illicit procurement; Role of export controls in stopping proliferation; Increasing the transparency of gas centrifuge programs in non-nuclear weapon states; and, Verified dismantlement of gas centrifuge programs. Gas centrifuges are important providers of low enriched uranium for civil nuclear power reactors. They also pose special nuclear proliferation risks. We all have special responsibilities to prevent the spread of gas centrifuges into regions of tension and to mitigate the consequences of their spread into the Middle East, South Asia, and North Asia.

Albright, David

2004-09-15

3

Laser and gas centrifuge enrichment  

SciTech Connect

Principles of uranium isotope enrichment using various laser and gas centrifuge techniques are briefly discussed. Examples on production of high enriched uranium are given. Concerns regarding the possibility of using low end technologies to produce weapons grade uranium are explained. Based on current assessments commercial enrichment services are able to cover the global needs of enriched uranium in the foreseeable future.

Heinonen, Olli [Senior Fellow, Belfer Center for Science and International Affairs, Harvard Kennedy School, Cambridge, Massachusetts (United States)

2014-05-09

4

The effect of gas fraction on centrifugal pump  

NASA Astrophysics Data System (ADS)

In order to study the multiphase flow field in M125 centrifugal pump, three-dimensional modeling was used for internal flow through three-dimensional software Pro/E. Then based on SST turbulence model combining with Rayleigh-Plesset cavitation model, and structured grid to simulate the hydraulic characteristics of volute and impeller within different gas conditions. The velocity, pressure and gas volume fraction distributions of the interior flow field of volute and impeller were obtained and analyzed, which revealed the effect of gas fractions on the flow characteristic of the centrifugal pump.

Zhu, Z. T.; Wang, Y.; Zhao, L. F.; Ning, C.; Xie, S. F.; Liu, Z. C.

2015-01-01

5

Centrifugation  

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 centrifugation, operating a centrifuge, and hazards and safety. After completing a guided centrifuge practice, students take a quiz to assess their learning.

6

Experiments with background gas in a vacuum arc centrifuge  

SciTech Connect

Since promising isotope separation results were first reported by Krishnan et al. in 1981, a range of vacuum arc centrifuge experiments have been conducted in laboratories around the world. The PCEN (Plasma CENtrifuge) vacuum arc centrifuge at the Brazilian National Institute for Space Research has been used for isotope separation studies with cathode materials of carbon and magnesium and also to investigate the performance in terms of the rotational velocity attained for different cathode materials. Here, a vacuum arc centrifuge has been operated with an initial filling gas of either argon or hydrogen for pressures ranging from 10{sup {minus}3} to 10{sup {minus}1} Pa. The angular velocity {omega} of the plasma has been determined by cross-correlating the signals from potential probes, and the electron temperature T has been deduced from Langmuir probe data. At high gas pressures and early times during the 14 ms plasma lifetime, high-frequency nonuniformities frequently observed in the vacuum discharge disappear, suggesting that the associated instability is suppressed. Under the same conditions, nonuniformities rotating with much lower angular velocities are observed in the plasma. Temperatures are reduced in the presence of the background gas, and the theoretical figure of merit for separation proportional to {omega}{sup 2}/T is increased compared to its value in the vacuum discharge for both argon and hydrogen gas fillings.

Dallaqua, R.S.; Simpson, S.W.; Del Bosco, E. [Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos (Brazil). Laboratorio Associado de Plasma] [Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos (Brazil). Laboratorio Associado de Plasma

1996-04-01

7

Gas Centrifuge Enrichment Plant seismic time history development  

Microsoft Academic Search

The objective of this study is to generate a number of artificial-spectrum consistent-time histories for use in the seismic analysis of the Gas Centrifuge Enrichment Plant (GCEP) service modules (SM). The method used in the generation of the artificial time histories presented in this report makes use of the fast Fourier transform (FFT) algorithm to modify the Fourier frequency spectrum

G. A. Aramayo; T. G. Carley

1979-01-01

8

Gas Centrifuge Enrichment Plant Safeguards System Modeling  

SciTech Connect

The U.S. Department of Energy (DOE) is interested in developing tools and methods for potential U.S. use in designing and evaluating safeguards systems used in enrichment facilities. This research focuses on analyzing the effectiveness of the safeguards in protecting against the range of safeguards concerns for enrichment plants, including diversion of attractive material and unauthorized modes of use. We developed an Extend simulation model for a generic medium-sized centrifuge enrichment plant. We modeled the material flow in normal operation, plant operational upset modes, and selected diversion scenarios, for selected safeguards systems. Simulation modeling is used to analyze both authorized and unauthorized use of a plant and the flow of safeguards information. Simulation tracks the movement of materials and isotopes, identifies the signatures of unauthorized use, tracks the flow and compilation of safeguards data, and evaluates the effectiveness of the safeguards system in detecting misuse signatures. The simulation model developed could be of use to the International Atomic Energy Agency IAEA, enabling the IAEA to observe and draw conclusions that uranium enrichment facilities are being used only within authorized limits for peaceful uses of nuclear energy. It will evaluate improved approaches to nonproliferation concerns, facilitating deployment of enhanced and cost-effective safeguards systems for an important part of the nuclear power fuel cycle.

Elayat, H A; O'Connell, W J; Boyer, B D

2006-06-05

9

Theory and experiments on centrifuge cratering  

SciTech Connect

Centrifuge experimental techniques provide possibilities for laboratory simulation of ground motion and cratering effects due to explosive loadings. The results of a similarity analysis for the thermomechanical response of a continuun show that increased gravity is a necessary condition for subscale testing when identical materials for both model and prototype are being used. The general similarity requirements for this type of subscale testing are examined both theoretically and experimentally. The similarity analysis is used to derive the necessary and sufficient requirements due to the general balance and jump equations and gives relations among all the scale factors for size, density, stress, body forces, internal energy, heat supply, heat conduction, heat of detonation, and time. Additional constraints due to specific choices of material constitutive equations are evaluated separately. The class of consitutive equations that add no further requirements is identified. For this class of materials, direct simulation of large-scale cratering events at small scale on the centrifuge is possible and independent of the actual constitutive equations. For a rare-independent soil it is shown that a small experiment at gravity g and energy E is similar to a large event at 1 G but with energy equal to g/sup 3/E. Consequently, experiments at 500 G with 8 grams of explosives can be used to

Schmidt, R.M.; Holsapple, K.A.

1980-01-10

10

Modeling of UF{sub 6} enrichment with gas centrifuges for nuclear safeguards activities  

SciTech Connect

The physical modeling of uranium isotopes ({sup 235}U, {sup 238}U) separation process by centrifugation of is a key aspect for predicting the nuclear fuel enrichment plant performances under surveillance by the Nuclear Safeguards Authorities. In this paper are illustrated some aspects of the modeling of fast centrifuges for UF{sub 6} gas enrichment and of a typical cascade enrichment plant with the Theoretical Centrifuge and Cascade Simulator (TCCS). The background theory for reproducing the flow field characteristics of a centrifuge is derived from the work of Cohen where the separation parameters are calculated using the solution of a differential enrichment equation. In our case we chose to solve the hydrodynamic equations for the motion of a compressible fluid in a centrifugal field using the Berman - Olander vertical velocity radial distribution and the solution was obtained using the Matlab software tool. The importance of a correct estimation of the centrifuge separation parameters at different flow regimes, lies in the possibility to estimate in a reliable way the U enrichment plant performances, once the separation external parameters are set (feed flow rate and feed, product and tails assays). Using the separation parameters of a single centrifuge allow to determine the performances of an entire cascade and, for this purpose; the software Simulink was used. The outputs of the calculation are the concentrations (assays) and the flow rates of the enriched (product) and depleted (tails) gas mixture. These models represent a valid additional tool, in order to verify the compliance of the U enrichment plant operator declarations with the 'on site' inspectors' measurements.

Mercurio, G.; Peerani, P.; Richir, P.; Janssens, W.; Eklund, G. [European Commission, Joint Research Centre, Institute for Transuranium Elements Via Fermi, 2749-TP181,20127 Ispra (Italy)

2012-09-26

11

Modeling of UF6 enrichment with gas centrifuges for nuclear safeguards activities  

NASA Astrophysics Data System (ADS)

The physical modeling of uranium isotopes (235U, 238U) separation process by centrifugation of is a key aspect for predicting the nuclear fuel enrichment plant performances under surveillance by the Nuclear Safeguards Authorities. In this paper are illustrated some aspects of the modeling of fast centrifuges for UF6 gas enrichment and of a typical cascade enrichment plant with the Theoretical Centrifuge and Cascade Simulator (TCCS). The background theory for reproducing the flow field characteristics of a centrifuge is derived from the work of Cohen [1] where the separation parameters are calculated using the solution of a differential enrichment equation. In our case we chose to solve the hydrodynamic equations for the motion of a compressible fluid in a centrifugal field using the Berman - Olander vertical velocity radial distribution [2] and the solution was obtained using the Matlab software tool [3]. The importance of a correct estimation of the centrifuge separation parameters at different flow regimes, lies in the possibility to estimate in a reliable way the U enrichment plant performances, once the separation external parameters are set (feed flow rate and feed, product and tails assays)[4]. Using the separation parameters of a single centrifuge allow to determine the performances of an entire cascade and, for this purpose; the software Simulink [3] was used. The outputs of the calculation are the concentrations (assays) and the flow rates of the enriched (product) and depleted (tails) gas mixture. These models represent a valid additional tool, in order to verify the compliance of the U enrichment plant operator declarations with the "on site" inspectors' measurements.

Mercurio, G.; Peerani, P.; Richir, P.; Janssens, W.; Eklund, G.

2012-09-01

12

Centrifugal compression of soft particle packings: Theory and experiment K. N. Nordstrom,1  

E-print Network

Centrifugal compression of soft particle packings: Theory and experiment K. N. Nordstrom,1 E to centrifugal compression, for arbitrary constitutive relation between stress and strain. Example solutions by centrifugal compression, and we illustrate our method with experiments on 1 m diam- eter NIPA microgel beads

Gollub, Jerry P.

13

New generation enrichment monitoring technology for gas centrifuge enrichment plants  

SciTech Connect

The continuous enrichment monitor, developed and fielded in the 1990s by the International Atomic Energy Agency, provided a go-no-go capability to distinguish between UF{sub 6} containing low enriched (approximately 4% {sup 235}U) and highly enriched (above 20% {sup 235}U) uranium. This instrument used the 22-keV line from a {sup 109}Cd source as a transmission source to achieve a high sensitivity to the UF{sub 6} gas absorption. The 1.27-yr half-life required that the source be periodically replaced and the instrument recalibrated. The instrument's functionality and accuracy were limited by the fact that measured gas density and gas pressure were treated as confidential facility information. The modern safeguarding of a gas centrifuge enrichment plant producing low-enriched UF{sub 6} product aims toward a more quantitative flow and enrichment monitoring concept that sets new standards for accuracy stability, and confidence. An instrument must be accurate enough to detect the diversion of a significant quantity of material, have virtually zero false alarms, and protect the operator's proprietary process information. We discuss a new concept for advanced gas enrichment assay measurement technology. This design concept eliminates the need for the periodic replacement of a radioactive source as well as the need for maintenance by experts. Some initial experimental results will be presented.

Ianakiev, Kiril D [Los Alamos National Laboratory; Alexandrov, Boian, S. [Los Alamos National Laboratory; Boyer, Brian, D. [Los Alamos National Laboratory; Hill, Thomas, R. [Los Alamos National Laboratory; Macarthur, Duncan, W. [Los Alamos National Laboratory; Marks, Thomas [Los Alamos National Laboratory; Moss, Calvin, E. [Los Alamos National Laboratory; Sheppard, Gregory, A. [Los Alamos National Laboratory; Swinhoe, Martyn, T. [Los Alamos National Laboratory

2008-01-01

14

Simulation of countercurrent flow in a gas centrifuge  

NASA Astrophysics Data System (ADS)

Certain effects of geometry and configuration on the circulation patterns in a gas centrifuge can be readily explored and tested in a liquid simulator. Since the most interesting situations involve countercurrent flows, the simulator must be one in which such motion is both easy to produce and accessible for experimentation. An apparatus that seems to meet these requirements is a partially filled rotating cylinder, which has one endplate that rotates with a slightly different angular velocity. The device, shown schematically can be modified to produce source-sink or mass driven flows as well. The rotation rates, fluid volume fraction (i.e., the thickness of the fluid layer) and the fluid rheology are the main control factors to be set in any experiment.

Greenspan, H. P.

1982-04-01

15

Simulation of countercurrent flow in a gas centrifuge  

SciTech Connect

Certain effects of geometry and configuration on the circulation patterns in a gas centrifuge can be readily explored and tested in a liquid simulator. Since the most interesting situations involve countercurrent flows, the simulator must be one in which such motion is both easy to produce and accessible for experimentation. An apparatus that seems to meet these requirements is a partially filled rotating cylinder, which has one endplate that rotates with a slightly different angular velocity. The device, shown schematically can be modified to produce source-sink or mass driven flows as well. The rotation rates, fluid volume fraction (i.e., the thickness of the fluid layer) and the fluid rheology are the main control factors to be set in any experiment.

Greenspan, H.P.

1982-04-22

16

Analysis of gas centrifuge cascade for separation of multicomponent isotopes and optimal feed position  

SciTech Connect

Analysis of the concentration distribution in a gas centrifuge cascade for separation of multicomponent isotope mixtures is different from that in a cascade for separation of two-component mixtures. This paper presents the governing equations for a multicomponent isotope separation cascade. Numerically predicted separation factors for the gas centrifuge cascade agree well with the experimental data. A theoretical optimal feed position is derived for a short square cascade for a two-component mixture in a close-separation case. The optimal feed position for a gas centrifuge cascade for separation of multicomponent mixture is discussed.

Chuntong Ying; Hongjiang Wu; Mingsheng Zhou; Yuguang Nie; Guangjun Liu [Tsinghua Univ., Beijing (China)

1997-10-01

17

New Measures to Safeguard Gas Centrifuge Enrichment Plants  

SciTech Connect

As Gas Centrifuge Enrichment Plants (GCEPs) increase in separative work unit (SWU) capacity, the current International Atomic Energy Agency (IAEA) model safeguards approach needs to be strengthened. New measures to increase the effectiveness of the safeguards approach are being investigated that will be mutually beneficial to the facility operators and the IAEA. One of the key concepts being studied for application at future GCEPs is embracing joint use equipment for process monitoring of load cells at feed and withdrawal (F/W) stations. A mock F/W system was built at Oak Ridge National Laboratory (ORNL) to generate and collect F/W data from an analogous system. The ORNL system has been used to collect data representing several realistic normal process and off-normal (including diversion) scenarios. Emphasis is placed on the novelty of the analysis of data from the sensors as well as the ability to build information out of raw data, which facilitates a more effective and efficient verification process. This paper will provide a progress report on recent accomplishments and next steps.

Whitaker, Jr., James [ORNL; Garner, James R [ORNL; Whitaker, Michael [ORNL; Lockwood, Dunbar [U.S. Department of Energy, NNSA; Gilligan, Kimberly V [ORNL; Younkin, James R [ORNL; Hooper, David A [ORNL; Henkel, James J [ORNL; Krichinsky, Alan M [ORNL

2011-01-01

18

Defining the needs for gas centrifuge enrichment plants advanced safeguards  

SciTech Connect

Current safeguards approaches used by the International Atomic Energy Agency (IAEA) at gas centrifuge enrichment plants (GCEPs) need enhancement in order to verify declared low-enriched (LEU) production, detect undeclared LEU production and detect highly enriched uranium (HEU) production with adequate detection probability using nondestructive assay (NDA) techniques. At present inspectors use attended systems, systems needing the presence of an inspector for operation, during inspections to verify the mass and {sup 235}U enrichment of declared UF{sub 6} containers used in the process of enrichment at GCEPs. In verifying declared LEU production, the inspectors also take samples for off-site destructive assay (DA) which provide accurate data, with 0.1% to 0.5% measurement uncertainty, on the enrichment of the UF{sub 6} feed, tails, and product. However, taking samples of UF{sub 6} for off-site analysis is a much more labor and resource intensive exercise for the operator and inspector. Furthermore, the operator must ship the samples off-site to the IAEA laboratory which delays the timeliness of results and interruptions to the continuity of knowledge (CofK) of the samples during their storage and transit. This paper contains an analysis of possible improvements in unattended and attended NDA systems such as process monitoring and possible on-site analysis of DA samples that could reduce the uncertainty of the inspector's measurements and provide more effective and efficient IAEA GCEPs safeguards. We also introduce examples advanced safeguards systems that could be assembled for unattended operation.

Boyer, Brian David [Los Alamos National Laboratory; Erpenbeck, Heather H [Los Alamos National Laboratory; Miller, Karen A [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Ianakiev, Kiril [Los Alamos National Laboratory; Marlowe, Johnna B [Los Alamos National Laboratory

2010-01-01

19

The effect of vacuum core boundary conditions on separation in the gas centrifuge  

Microsoft Academic Search

A vacuum exists in the central region of the cylindrical rotor of a high-speed countercurrent gas centrifuge when operated with UFâ for the enrichment of uranium. Since solutions of the Navier-Stokes equation are used to determine the isotopic distribution in the rotor, the location of the vacuum core boundary has a direct effect on the predicted separative work of the

Von Halle

1983-01-01

20

Effect of vacuum core boundary conditions on separation in the gas centrifuge  

Microsoft Academic Search

A vacuum exists in the central region of the cylindrical rotor of a high-speed countercurrent gas centrifuge when operated with UFâ for the enrichment of uranium. Since solutions of the Navier-Stokes equation are used to determine the isotopic distribution in the rotor, the location of the vacuum core boundary has a direct effect on the predicted separative work of the

E. Halle; R. A. Lowry; H. G. Wood

1983-01-01

21

Centrifugal compression of soft particle packings - theory and experiment  

E-print Network

An exact method is developed for computing the height of an elastic medium subjected to centrifugal compression, for arbitrary constitutive relation between stress and strain. Example solutions are obtained for power-law media and for cases where the stress diverges at a critical strain -- for example as required by packings composed of deformable but incompressible particles. Experimental data are presented for the centrifugal compression of thermo-responsive N-isopropylacrylamide (NIPA) microgel beads in water. For small radial acceleration, the results are consistent with Hertzian elasticity, and are analyzed in terms of the Young elastic modulus of the bead material. For large radial acceleration, the sample compression asymptotes to a value corresponding to a space-filling particle volume fraction of unity. Therefore we conclude that the gel beads are incompressible, and deform without deswelling. In addition, we find that the Young elastic modulus of the particulate gel material scales with cross-link density raised to the power 3.3+-0.8, somewhat larger than the Flory expectation.

K. N. Nordstrom; E. Verneuil; W. G. Ellenbroek; T. C. Lubensky; J. P. Gollub; D. J. Durian

2010-07-30

22

Centrifugal compression of soft particle packings: theory and experiment.  

PubMed

An exact method is developed for computing the height of an elastic medium subjected to centrifugal compression, for arbitrary constitutive relation between stress and strain. Example solutions are obtained for power-law media and for cases where the stress diverges at a critical strain--for example as required by packings composed of deformable but incompressible particles. Experimental data are presented for the centrifugal compression of thermo-responsive N-isopropylacrylamide (NIPA) microgel beads in water. For small radial acceleration, the results are consistent with Hertzian elasticity, and are analyzed in terms of the Young elastic modulus of the bead material. For large radial acceleration, the sample compression asymptotes to a value corresponding to a space-filling particle volume fraction of unity. Therefore we conclude that the gel beads are incompressible, and deform without deswelling. In addition, we find that the Young elastic modulus of the particulate gel material scales with cross-link density raised to the power 3.3±0.8, somewhat larger than the Flory expectation. PMID:21230273

Nordstrom, K N; Verneuil, E; Ellenbroek, W G; Lubensky, T C; Gollub, J P; Durian, D J

2010-10-01

23

Centrifugal compression of soft particle packings: Theory and experiment  

NASA Astrophysics Data System (ADS)

An exact method is developed for computing the height of an elastic medium subjected to centrifugal compression, for arbitrary constitutive relation between stress and strain. Example solutions are obtained for power-law media and for cases where the stress diverges at a critical strain—for example as required by packings composed of deformable but incompressible particles. Experimental data are presented for the centrifugal compression of thermo-responsive N-isopropylacrylamide (NIPA) microgel beads in water. For small radial acceleration, the results are consistent with Hertzian elasticity, and are analyzed in terms of the Young elastic modulus of the bead material. For large radial acceleration, the sample compression asymptotes to a value corresponding to a space-filling particle volume fraction of unity. Therefore we conclude that the gel beads are incompressible, and deform without deswelling. In addition, we find that the Young elastic modulus of the particulate gel material scales with cross-link density raised to the power 3.3±0.8 , somewhat larger than the Flory expectation.

Nordstrom, K. N.; Verneuil, E.; Ellenbroek, W. G.; Lubensky, T. C.; Gollub, J. P.; Durian, D. J.

2010-10-01

24

CFD Simulation of 3D Flow field in a Gas Centrifuge  

SciTech Connect

A CFD method was used to study the whole flow field in a gas centrifuge. In this paper, the VSM (Vector Splitting Method) of the FVM (Finite Volume Method) was used to solve the 3D Navier-Stokes equations. An implicit second-order upwind scheme was adopted. The numerical simulation was successfully performed on a parallel cluster computer and a convergence result was obtained. The simulation shows that: in the withdrawal chamber, a strong detached shock wave is formed in front of the scoop; as the radial position increases, the shock becomes stronger and the distance to scoop front surface is smaller. An oblique shock forms in the clearance between the scoop and the centrifuge wall; behind the shock-wave, the radially-inward motion of gas is induced because of the imbalance of the pressure gradient and the centrifugal force. In the separation chamber, a countercurrent is introduced. This indicates that CFD method can be used to study the complex three-dimensional flow field of gas centrifuges. (authors)

Dongjun Jiang; Shi Zeng [Tsinghua University, Beijing, 100084 (China)

2006-07-01

25

Performance and capacity of centrifugal gas cleaning devices  

Microsoft Academic Search

The purpose of dust control systems is to capture, collect and dispose of contaminant in an efficient manner. This research examines how to improve the operational and collection efficiency of gas cleaning devices via variations in geometry of different cyclone components. Unfortunately many of the predictive models provide inaccurate and contradictory results. Furthermore, many practical issues such as outlet and

Mohamed S Saad

2006-01-01

26

The production characteristics of a solution gas-drive reservoir as measured on a centrifugal model  

E-print Network

LIBRARY A 8I M COLLEGE OF TEXAS THE PRODUCTION CHARACTERISTICS OF A SOLUTION GAS-DRIVE RESERVOIR AS MEASURED ON A CENTRIFUGAL MIODEL A Thesis Robert J. Goodwin Submitted to the Graduate School of the Agricultural and Mechanical College... by Robert J. Goodwin Approved as to style and content by: Chairman of Co ttee Head of Department TABLE OF CONTENTS 1. ABSTRACT 2. INTRODUCTION 3. EQUIPMENT AND MATERIALS 4, PROCEDURE RESULTS AND DISCUSSION 6. CONCLUSIONS 7. ACKNOWLEDGEMENTS 8...

Goodwin, Robert Jennings

2012-06-07

27

A High Reliability Gas-driven Helium Cryogenic Centrifugal Compressor  

E-print Network

A helium cryogenic compressor was developed and tested in real conditions in 1996. The achieved objective was to compress 0.018 kg/s Helium at 4 K @ 1000 Pa (10 mbar) up to 3000 Pa (30 mbar). This project was an opportunity to develop and test an interesting new concept in view of future needs. The main features of this new specific technology are described. Particular attention is paid to the gas bearing supported rotor and to the pneumatic driver. Trade off between existing technologies and the present work are presented with special stress on the bearing system and the driver. The advantages are discussed, essentially focused on life time and high reliability without maintenance as well as non pollution characteristic. Practical operational modes are also described together with the experimental performances of the compressor. The article concludes with a brief outlook of future work.

Bonneton, M; Gistau-Baguer, Guy M; Turcat, F; Viennot, P

1998-01-01

28

Vortex centrifugal bubbling reactor  

Microsoft Academic Search

The vortex centrifugal bubbling apparatus is considered as a basis for a new type of multiphase vortex centrifugal bubbling reactor. In this device, a highly dispersed gas–liquid mixture is produced in the field of centrifugal forces inside the vortex chamber. The operation of the vortex centrifugal bubbling apparatus is based on the rotation of liquid by the tangential entry of

A. O. Kuzmin; M. Kh. Pravdina; A. I. Yavorsky; N. I. Yavorsky; V. N. Parmon

2005-01-01

29

Review of the gas centrifuge until 1962. Part II: Principles of high-speed rotation  

NASA Astrophysics Data System (ADS)

The principles of the separation physics of the gas centrifuge were described in Part I of this review. In this second section the principles involved in spinning the rotors of these centrifuges are described. Three types of rotor can be identified, depending on the ratio of length to diameter. If the rotor is very short, length-diameter ratio less than one, it is gyroscopically stable and easy to spin. If the length-diameter ratio is in the region of 4 or 5, the rotor behaves as a rigid body and is relatively easy to accelerate to speed; however, it has a tendency at full speed to exhibit gyroscopic precessions. Finally, if the length-diameter ratio is very large, the rotor becomes easy to stabilize gyroscopically, but it is difficult to get it to speed because long rotors are very flexible and have resonant frequencies of flexure lower than the operating speed. The problems of these three types of centrifuge (the rotor dynamics, the bearings used to support the rotor, and the stress analysis of the rotating components) were investigated in the last century as part of classical mechanics because of the emergence of steam turbines during the latter part of the industrial revolution. These early principles are briefly reviewed, with particular reference to the work of De Laval, who invented the principle of self-balancing, Reynolds and Evershed, who developed hydrodynamic and magnetic bearing, respectively, and Chree, who did the most extensive early work on the stress analysis of tubes and discs. The work is described as it applies to the centrifuges developed in America and Germany during the war and in the Soviet Union after the war. The work of Beams in America is described in most detail, since he and his colleagues developed all three types of centrifuge during the Manhattan Project. The other work described is that of Groth and Beyerle, who developed subcritical machines in Germany during the war, and of Steenbeck and Zippe, who helped to develop both subcritical and supercritical centrifuges in the Soviet Union after the war. Little of this latter work has been published, but Zippe redeveloped the subcritical machine at the University of Virginia. The description of this machine concludes the present review.

Whitley, Stanley

1984-01-01

30

Numerical investigation of the separation of sulfur isotopes in a single gas centrifuge  

SciTech Connect

A theoretical investigation of the separation of isotopic mixtures of average molecular mass between 100 and 200 is presented. Physical-mathematical and numerical models of transport processes in a gas centrifuge for a four component of sulfur hexafluoride are summarized. The analysis method developed was used to analyze the separation of stable chromium isotopes and other elements; it was determined that the efficiency as a function of the parameter studied is similar. The results also made it possible to determine the dependence of the separation capability on the molecular mass and physical properties of the working gases. 11 refs., 4 figs.

Borisevich, V.D.; Levin, E.V.; Yupatov, S.V.; Aisen, E.M. [Moscow Engineering Physics Institute (Russian Federation)

1994-12-01

31

FEMO, A FLOW AND ENRICHMENT MONITOR FOR VERIFYING COMPLIANCE WITH INTERNATIONAL SAFEGUARDS REQUIREMENTS AT A GAS CENTRIFUGE ENRICHMENT FACILITY  

Microsoft Academic Search

A number of countries have received construction licenses or are contemplating the construction of large-capacity gas centrifuge enrichment plants (GCEPs). The capability to independently verify nuclear material flows is a key component of international safeguards approaches, and the IAEA does not currently have an approved method to continuously monitor the mass flow of 235U in uranium hexafluoride (UF6) gas streams.

John E Gunning; Mark D Laughter; Jose A March-Leuba

2008-01-01

32

Realities of verifying the absence of highly enriched uranium (HEU) in gas centrifuge enrichment plants  

SciTech Connect

Over a two and one-half year period beginning in 1981, representatives of six countries (United States, United Kingdom, Federal Republic of Germany, Australia, The Netherlands, and Japan) and the inspectorate organizations of the International Atomic Energy Agency and EURATOM developed and agreed to a technically sound approach for verifying the absence of highly enriched uranium (HEU) in gas centrifuge enrichment plants. This effort, known as the Hexapartite Safeguards Project (HSP), led to the first international concensus on techniques and requirements for effective verification of the absence of weapons-grade nuclear materials production. Since that agreement, research and development has continued on the radiation detection technology-based technique that technically confirms the HSP goal is achievable. However, the realities of achieving the HSP goal of effective technical verification have not yet been fully attained. Issues such as design and operating conditions unique to each gas centrifuge plant, concern about the potential for sensitive technology disclosures, and on-site support requirements have hindered full implementation and operator support of the HSP agreement. In future arms control treaties that may limit or monitor fissile material production, the negotiators must recognize and account for the realities and practicalities in verifying the absence of HEU production. This paper will describe the experiences and realities of trying to achieve the goal of developing and implementing an effective approach for verifying the absence of HEU production. 3 figs.

Swindle, D.W.

1990-03-01

33

RADIO FREQUENCY IDENTIFICATION DEVICES: EFFECTIVENESS IN IMPROVING SAFEGUARDS AT GAS-CENTRIFUGE URANIUM-ENRICHMENT PLANTS.  

SciTech Connect

Recent advances in radio frequency identification devices (RFIDs) have engendered a growing interest among international safeguards experts. Potentially, RFIDs could reduce inspection work, viz. the number of inspections, number of samples, and duration of the visits, and thus improve the efficiency and effectiveness of international safeguards. This study systematically examined the applications of RFIDs for IAEA safeguards at large gas-centrifuge enrichment plants (GCEPs). These analyses are expected to help identify the requirements and desirable properties for RFIDs, to provide insights into which vulnerabilities matter most, and help formulate the required assurance tests. This work, specifically assesses the application of RFIDs for the ''Option 4'' safeguards approach, proposed by Bruce Moran, U. S. Nuclear Regulatory Commission (NRC), for large gas-centrifuge uranium-enrichment plants. The features of ''Option 4'' safeguards include placing RFIDs on all feed, product and tails (F/P/T) cylinders, along with WID readers in all FP/T stations and accountability scales. Other features of Moran's ''Option 4'' are Mailbox declarations, monitoring of load-cell-based weighing systems at the F/P/T stations and accountability scales, and continuous enrichment monitors. Relevant diversion paths were explored to evaluate how RFIDs improve the efficiency and effectiveness of safeguards. Additionally, the analysis addresses the use of RFIDs in conjunction with video monitoring and neutron detectors in a perimeter-monitoring approach to show that RFIDs can help to detect unidentified cylinders.

JOE,J.

2007-07-08

34

Centrifugal spray singlet oxygen generator for a COIL with nitrogen as a buffer gas  

NASA Astrophysics Data System (ADS)

A scalable high pressure centrifugal spray generator of singlet oxygen for chemical oxygen-iodine laser (COIL) was developed. This generator uses nitrogen as chlorine diluting gas. Different spray nozzles were tested which could be assembled together and so enable a high chlorine flow rates for a high-power COIL. The designed generator can produce singlet oxygen, O2(1?g), with reasonable chlorine utilization and O2(1?g) yield even at very high generator pressures, which cannot be attained by other O2(1?g) generators. This high-pressure operation is beneficial for a pressure recovery system of the laser. Another advantage of this generator is a very high BHP utilization. The problem of heating of exit gas was solved by introducing additional nitrogen between the separator rotor and stator.

Å palek, Otomar; Jirásek, Vít.; ?enský, Miroslav; Kodymová, Jarmila

2012-01-01

35

Concentration by centrifugation for gas exchange EPR oximetry measurements with loop-gap resonators  

NASA Astrophysics Data System (ADS)

Measurement of the bimolecular collision rate between a spin label and oxygen is conveniently carried out using a gas permeable plastic sample tube of small diameter that fits a loop-gap resonator. It is often desirable to concentrate the sample by centrifugation in order to improve the signal-to-noise ratio (SNR), but the deformable nature of small plastic sample tubes presents technical problems. Solutions to these problems are described. Two geometries were considered: (i) a methylpentene polymer, TPX, from Mitsui Chemicals, at X-band and (ii) Teflon tubing with 0.075 mm wall thickness at Q-band. Sample holders were fabricated from Delrin that fit the Eppendorf microcentrifuge tubes and support the sample capillaries. For TPX, pressure of the sealant at the end of the sample tube against the Delrin sample holder provided an adequate seal. For Teflon, the holder permitted introduction of water around the tube in order to equalize pressures across the sealant during centrifugation. Typically, the SNR was improved by a factor of five to eight. Oxygen accessibility applications in site-directed spin labeling studies are discussed.

Subczynski, Witold K.; Felix, Christopher C.; Klug, Candice S.; Hyde, James S.

2005-10-01

36

What happens when stems are embolized in a centrifuge? Testing the cavitron theory.  

PubMed

Vulnerability curves (VCs) measure the ability of vessels to retain metastable water without embolisms that lower the hydraulic conductivity of stems. The fastest method of measuring VCs is the centrifuge technique and the Cochard cavitron is a method that allows measurement of hydraulic conductivity of stems while they are spinning. This paper describes the pattern of embolism that results after spinning the stems of hybrid aspen (Populus tremula×P. tremuloides) and two hybrid cottonwoods (P38P38 P. balsamifera×P. simonii and Northwest, which is a hybrid of P. deltoides×P. balsamifera). It is recognized that the pattern of embolism induced in a centrifuge ought to differ from the pattern during natural dehydration of plants because the profiles of tension vs distance greatly differ under the two modes of inducing stress. The pattern of embolism was visualized by a staining technique and quantified by traditional measurements of percentage loss conductivity (PLC) performed on subsample segments excised from spun stems. We found a pattern of embolism approximating that expected from theory: (1) PLC near the axis of rotation exceeded the average; (2) PLC was quite high near the ends of the stems, even though tension ought to be zero; (3) large vessels cavitated before small vessels; (4) more embolism occurred near the base than near the apex of the stems. However, we could not always scale up from subsample conductivity and PLC to whole-stem conductivity. This pattern of embolism is interpreted in terms of vessel diameter and vessel length. PMID:20663083

Cai, Jing; Hacke, Uwe; Zhang, Shuoxin; Tyree, Melvin T

2010-12-01

37

A Monte Carlo Analysis of Gas Centrifuge Enrichment Plant Process Load Cell Data  

SciTech Connect

As uranium enrichment plants increase in number, capacity, and types of separative technology deployed (e.g., gas centrifuge, laser, etc.), more automated safeguards measures are needed to enable the IAEA to maintain safeguards effectiveness in a fiscally constrained environment. Monitoring load cell data can significantly increase the IAEA s ability to efficiently achieve the fundamental safeguards objective of confirming operations as declared (i.e., no undeclared activities), but care must be taken to fully protect the operator s proprietary and classified information related to operations. Staff at ORNL, LANL, JRC/ISPRA, and University of Glasgow are investigating monitoring the process load cells at feed and withdrawal (F/W) stations to improve international safeguards at enrichment plants. A key question that must be resolved is what is the necessary frequency of recording data from the process F/W stations? Several studies have analyzed data collected at a fixed frequency. This paper contributes to load cell process monitoring research by presenting an analysis of Monte Carlo simulations to determine the expected errors caused by low frequency sampling and its impact on material balance calculations.

Garner, James R [ORNL; Whitaker, J Michael [ORNL

2013-01-01

38

Analysis of the effectiveness of gas centrifuge enrichment plants advanced safeguards  

SciTech Connect

Current safeguards approaches used by the International Atomic Energy Agency (IAEA) at gas centrifuge enrichment plants (GCEPs) need enhancement in order to verify declared low-enriched uranium (LEU) production, detect undeclared LEU production and detect highly enriched uranium (HEU) production with adequate detection probability using non destructive assay (NDA) techniques. At present inspectors use attended systems, systems needing the presence of an inspector for operation, during inspections to verify the mass and 235U enrichment of declared UF6 containers used in the process of enrichment at GCEPs. This paper contains an analysis of possible improvements in unattended and attended NDA systems including process monitoring and possible on-site destructive assay (DA) of samples that could reduce the uncertainty of the inspector's measurements. These improvements could reduce the difference between the operator's and inspector's measurements providing more effective and efficient IAEA GCEPs safeguards. We also explore how a few advanced safeguards systems could be assembled for unattended operation. The analysis will focus on how unannounced inspections (UIs), and the concept of information-driven inspections (IDS) can affect probability of detection of the diversion of nuclear materials when coupled to new GCEPs safeguards regimes augmented with unattended systems.

Boyer, Brian David [Los Alamos National Laboratory; Erpenbeck, Heather H [Los Alamos National Laboratory; Miller, Karen A [Los Alamos National Laboratory; Swinjoe, Martyn T [Los Alamos National Laboratory; Ianakiev, Kiril D [Los Alamos National Laboratory; Marlow, Johnna B [Los Alamos National Laboratory

2010-01-01

39

Gas centrifuge enrichment plants inspection frequency and remote monitoring issues for advanced safeguards implementation  

SciTech Connect

Current safeguards approaches used by the IAEA at gas centrifuge enrichment plants (GCEPs) need enhancement in order to verify declared low enriched uranium (LEU) production, detect undeclared LEU production and detect high enriched uranium (BEU) production with adequate probability using non destructive assay (NDA) techniques. At present inspectors use attended systems, systems needing the presence of an inspector for operation, during inspections to verify the mass and {sup 235}U enrichment of declared cylinders of uranium hexafluoride that are used in the process of enrichment at GCEPs. This paper contains an analysis of how possible improvements in unattended and attended NDA systems including process monitoring and possible on-site destructive analysis (DA) of samples could reduce the uncertainty of the inspector's measurements providing more effective and efficient IAEA GCEPs safeguards. We have also studied a few advanced safeguards systems that could be assembled for unattended operation and the level of performance needed from these systems to provide more effective safeguards. The analysis also considers how short notice random inspections, unannounced inspections (UIs), and the concept of information-driven inspections can affect probability of detection of the diversion of nuclear material when coupled to new GCEPs safeguards regimes augmented with unattended systems. We also explore the effects of system failures and operator tampering on meeting safeguards goals for quantity and timeliness and the measures needed to recover from such failures and anomalies.

Boyer, Brian David [Los Alamos National Laboratory; Erpenbeck, Heather H [Los Alamos National Laboratory; Miller, Karen A [Los Alamos National Laboratory; Ianakiev, Kiril D [Los Alamos National Laboratory; Reimold, Benjamin A [Los Alamos National Laboratory; Ward, Steven L [Los Alamos National Laboratory; Howell, John [GLASGOW UNIV.

2010-09-13

40

In-Born Radio Frequency Identification Devices for Safeguards Use at Gas-Centrifuge Enrichment Plants  

SciTech Connect

Global expansion of nuclear power has made the need for improved safeguards measures at Gas Centrifuge Enrichment Plants (GCEPs) imperative. One technology under consideration for safeguards applications is Radio Frequency Identification Devices (RFIDs). RFIDs have the potential to increase IAEA inspector"s efficiency and effectiveness either by reducing the number of inspection visits necessary or by reducing inspection effort at those visits. This study assesses the use of RFIDs as an integral component of the "Option 4" safeguards approach developed by Bruce Moran, U.S. Nuclear Regulatory Commission (NRC), for a model GCEP [1]. A previous analysis of RFIDs was conducted by Jae Jo, Brookhaven National Laboratory (BNL), which evaluated the effectiveness of an RFID tag applied by the facility operator [2]. This paper presents a similar evaluation carried out in the framework of Jo’s paper, but it is predicated on the assumption that the RFID tag is applied by the manufacturer at the birth of the cylinder, rather than by the operator. Relevant diversion scenarios are examined to determine if RFIDs increase the effectiveness and/ or efficiency of safeguards in these scenarios. Conclusions on the benefits offered to inspectors by using in-born RFID tagging are presented.

Ward,R.; Rosenthal,M.

2009-07-12

41

Nuclear material safeguards for enrichments plants: Part 4, Gas Centrifuge Enrichment Plant: Diversion scenarios and IAEA safeguards activities: Safeguards training course  

SciTech Connect

This publication is Part 4 of a safeguards training course in Nuclear Material Safeguards for enrichment plants. This part of the course deals with diversion scenarios and safeguards activities at gas centrifuge enrichment plants.

Not Available

1988-10-01

42

A Robust Infrastructure Design for Gas Centrifuge Enrichment Plant Unattended Online Enrichment Monitoring  

SciTech Connect

An online enrichment monitor (OLEM) is being developed to continuously measure the relative isotopic composition of UF6 in the unit header pipes of a gas centrifuge enrichment plant (GCEP). From a safeguards perspective, OLEM will provide early detection of a facility being misused for production of highly enriched uranium. OLEM may also reduce the number of samples collected for destructive assay and if coupled with load cell monitoring can provide isotope mass balance verification. The OLEM design includes power and network connections for continuous monitoring of the UF6 enrichment and state of health of the instrument. Monitoring the enrichment on all header pipes at a typical GCEP could require OLEM detectors on each of the product, tails, and feed header pipes. If there are eight process units, up to 24 detectors may be required at a modern GCEP. Distant locations, harsh industrial environments, and safeguards continuity of knowledge requirements all place certain demands on the network robustness and power reliability. This paper describes the infrastructure and architecture of an OLEM system based on OLEM collection nodes on the unit header pipes and power and network support nodes for groupings of the collection nodes. A redundant, self-healing communications network, distributed backup power, and a secure communications methodology. Two candidate technologies being considered for secure communications are the Object Linking and Embedding for Process Control Unified Architecture cross-platform, service-oriented architecture model for process control communications and the emerging IAEA Real-time And INtegrated STream-Oriented Remote Monitoring (RAINSTORM) framework to provide the common secure communication infrastructure for remote, unattended monitoring systems. The proposed infrastructure design offers modular, commercial components, plug-and-play extensibility for GCEP deployments, and is intended to meet the guidelines and requirements for unattended and remotely monitored safeguards systems.

Younkin, James R [ORNL; Rowe, Nathan C [ORNL; Garner, James R [ORNL

2012-01-01

43

The application and field experience of high strength 12% Cr centrifugally cast pipe for gas gathering system  

SciTech Connect

Centrifugal cast method is one of the processes to provide high quality seamless pipe. The advantages of the process are (1) heavy wall pipe can be manufactured (2) relatively flexible in material selection for manufacturing pipe. For sweet corrosion environment caused by CO{sub 2} where carbon steels can not be used, centrifugally cast 12% Cr martensitic stainless steel pipes and fittings have been developed. One of the key factors of this material applied to pipeline is the weldability, especially high hardness of the welds or its heat affected zone which causes for brittle rupture as well as stress corrosion cracking of the pipeline. Cast 12% Cr pipe which has high strength with low hardness even at the weld joint has been developed. Besides of the development of straight pipe, several types of fittings have been developed. These pipes and fittings have been used for natural gas gathering lines and booster compression lines in sweet corrosion service.

Yoshitake, A.; Teraoka, M.; Torigoe, T. [Kubota Corp., Hirakata, Osaka (Japan). Hirakata Plant; Amako, S. [Kubota America Corp., Houston, TX (United States)

1995-10-01

44

Analytical calibration of the two-geometry method for uranium enrichment verification in a gas centrifuge  

Microsoft Academic Search

The two-geometry method is an approved technique to verify the uranium enrichment of UF6 in centrifuge cascade header pipes. Two analytical calculations, Monte Carlo and numerical integration of expressions derived from geometrical arguments, have been applied to determine the detector geometry constants to simplify optimizing the pair of detector collimator geometries. Comparisons are presented for two pairs of collimators: an

D. A. Close; H. F. Atwater

1990-01-01

45

Splitter-bladed centrifugal compressor impeller designed for automotive gas turbine application. [at the Lewis Research Center  

NASA Technical Reports Server (NTRS)

Mechanical design and fabrication of two splitter-bladed centrifugal compressor impellers were completed for rig testing at NASA Lewis Research Center. These impellers were designed for automotive gas turbine application. The mechanical design was based on NASA specifications for blade-shape and flowpath configurations. The contractor made engineering drawings and performed calculations for mass and center-of-gravity, for stress and vibration analyses, and for shaft critical speed analysis. One impeller was machined to print; the other had a blade height and exit radius of 2.54 mm larger than print dimensions.

Pampreen, R. C.

1977-01-01

46

An empirical model approach to gas evolution reactions in a centrifugal field  

Microsoft Academic Search

The application of a centrifugal field has been demonstrated to intensify the water electrolysis process. Data collected from the linear sweep voltammetry and steady-state measurements showed that an anode potential reduction of up to 0.18 V, a cathode potential reduction of up to 0.20 V, an ohmic voltage reduction of up to 0.25 V and a cell voltage reduction of

H Cheng; K Scott

2003-01-01

47

Filtering centrifuge  

Microsoft Academic Search

Below, we propose a new automatic airtight filtering centrifuge for separating suspensions containing a nonabrasive solid phase with a particle size greater than 10 #m, andwe presentthe results of atest ofanexperimental model of such a centrifuge. It is based on a slotted-type screen. The centrifuge was developed and tested under laboratory conditions and in an experimental polyethylene-syn thesis unit in

A. E. Solokhnenko; V. I. Kukushkin

1978-01-01

48

RESEARCH AND DEVELOPMENT OF AN INTEGRAL SEPARATOR FOR A CENTRIFUGAL GAS PROCESSING FACILITY  

SciTech Connect

A COMPACT GAS PROCESSING DEVICE WAS INVESTIGATED TO INCREASE GAS PRODUCTION FROM REMOTE, PREVIOUSLY UN-ECONOMIC RESOURCES. THE UNIT WAS TESTED ON AIR AND WATER AND WITH NATURAL GAS AND LIQUID. RESULTS ARE REPORTED WITH RECOMMENDATIONS FOR FUTURE WORK.

LANCE HAYS

2007-02-27

49

Centrifugal bubble O{sub 2} ({sup 1{Delta}}) gas generator with a total pressure of 100 Torr  

SciTech Connect

A centrifugal bubbling singlet-oxygen gas generator is developed in which chlorine with helium are injected into the rotating layer of the alkali solution of hydrogen peroxide through cylindrical nozzles directed at an angle of 30{sup 0} to the bubbler surface. The concentrations of water vapour and O{sub 2} ({sup 1{Delta}}) and the gas temperature were determined by using the multichannel recording of the emission bands of oxygen at 634, 703, 762 and 1268 nm. For the chlorine and helium flow rates of 60 and 90 mmol s{sup -1}, respectively, the specific chlorine load of 3.2 mmol cm{sup -2}, a total pressure of 100 Torr in the working region of the gas generator and the oxygen partial pressure of 36 Torr, the chlorine utilisation was 90% and the content of O{sub 2} ({sup 1{Delta}}) was {approx}60%. For the ratio of the flow rates of chlorine and the alkali solution of hydrogen peroxide equal to 1 mol L{sup -1}, the water vapour content was {approx}25%. The chemical efficiency of the oxygen-iodine laser with this gas generator achieved 23% for the specific power of 12.7 W cm per 1 cm{sup 3} s{sup -1} per pass of the solution through the gas generator. (laser applications and other topics in quantum electronics)

Zagidulin, M V; Nikolaev, V D; Svistun, M I; Khvatov, N A [Samara Branch of the P. N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2008-08-31

50

Simulation of the heat exchange between the supersonic flow and the stationary body in a gas centrifuge  

NASA Astrophysics Data System (ADS)

We have made comparative calculations of the heat exchange in the subpersonic flow of gaseous UF6 around the stationary cylindrical body inside the rotating rotor of the gas centrifuge. It has been revealed that the integral heat flux from the gas to the body calculated with the use of the ANSYS-CFX program complex from the viewpoint of the continuum model is much smaller than the heat flow calculated by the Monte Carlo method of direct statistical simulation. Estimates show that under the conditions being considered the boundary layer on the surface of the body has no time to be formed and has a thickness of the order of the mean free path of the gas molecules and, therefore, the use of the methods of continuum mechanics in this region is incorrect. On the contrary, the method of direct statistical simulation permits taking into account the interaction of gas molecules directly with the surface of the streamline body and obtaining more correct results.

Zvonarev, K. V.; Seleznev, V. D.; Tokmantsev, V. I.; Abramov, Yu. V.

2012-11-01

51

Procedures for the calculation of the separative performance of a countercurrent gas centrifuge  

NASA Astrophysics Data System (ADS)

The approximations used in the development of the standard Onsager-Cohen gradient equation produce results which depart from the more detailed solutions presented in one direction in the enriching section and in the other direction in the stripping section and the errors therefore tend to cancel for the machine as a whole. It follows that for a centrifuge in which most of the bowl is used as an enriching section or as a stripping section this cancellation would not occur and some appreciable error would result from the use of the standard Onsager-Cohen gradient equation. A modified Onsager-Cohen gradient equation is therefore recommended in preference to the standard Onsager-Cohen gradient equation. It is shown in the results of calculations that indeed very little effect is observed by neglecting the term in the gradient equation containing the second derivative of the concentration.

Vonhalle, E.

1981-07-01

52

Defining the needs for non-destructive assay of UF6 feed, product, and tails at gas centrifuge enrichment plants and possible next steps  

Microsoft Academic Search

Current safeguards approaches used by the IAEA at gas centrifuge enrichment plants (GCEPs) need enhancement in order to detect undeclared LEU production with adequate detection probability using non destructive assay (NDA) techniques. At present inspectors use attended systems, systems needing the presence of an inspector for operation, during inspections to verify the mass and ²³U enrichment of UF bulk material

Brian D Boyer; Martyn T Swinhoe; Bruce W Moran; Alain Lebrun

2009-01-01

53

Centrifugal adsorption system  

NASA Technical Reports Server (NTRS)

A gas-liquid separator uses a helical passageway to impart a spiral motion to a fluid passing therethrough. The centrifugal force generated by the spiraling motion urges the liquid component of the fluid radially outward which forces the gas component radially inward. The gas component is then separated through a gas-permeable, liquid-impervious membrane and discharged through a central passageway. A filter material captures target substances contained in the fluid.

Gonda, Steve R. (Inventor); Tsao, Yow-Min D. (Inventor); Lee, Wenshan (Inventor)

2006-01-01

54

PROCESS GAS APPLICATIONS WHERE API 619 SCREW COMPRESSORS REPLACED RECIPROCATING AND CENTRIFUGAL COMPRESSORS  

Microsoft Academic Search

Oil-free screw compressors have been used for process gas application since the 1970s. Oil-flooded screw compressors have been used in many process related applications since the 1980s. Oil-flooded screw compressors are covered in the latest edition of API Standard 619 issued in 2004. Both oil-free and oil-flooded screw compressors have been expanding into process gas com- pression applications. It is

Takao Ohama; Yoshinori Kurioka; Takao Koga

55

FEMO, A FLOW AND ENRICHMENT MONITOR FOR VERIFYING COMPLIANCE WITH INTERNATIONAL SAFEGUARDS REQUIREMENTS AT A GAS CENTRIFUGE ENRICHMENT FACILITY  

SciTech Connect

A number of countries have received construction licenses or are contemplating the construction of large-capacity gas centrifuge enrichment plants (GCEPs). The capability to independently verify nuclear material flows is a key component of international safeguards approaches, and the IAEA does not currently have an approved method to continuously monitor the mass flow of 235U in uranium hexafluoride (UF6) gas streams. Oak Ridge National Laboratory is investigating the development of a flow and enrichment monitor, or FEMO, based on an existing blend-down monitoring system (BDMS). The BDMS was designed to continuously monitor both 235U mass flow and enrichment of UF6 streams at the low pressures similar to those which exists at GCEPs. BDMSs have been installed at three sites-the first unit has operated successfully in an unattended environment for approximately 10 years. To be acceptable to GCEP operators, it is essential that the instrument be installed and maintained without interrupting operations. A means to continuously verify flow as is proposed by FEMO will likely be needed to monitor safeguards at large-capacity plants. This will enable the safeguards effectiveness that currently exists at smaller plants to be maintained at the larger facilities and also has the potential to reduce labor costs associated with inspections at current and future plants. This paper describes the FEMO design requirements, operating capabilities, and development work required before field demonstration.

Gunning, John E [ORNL; Laughter, Mark D [ORNL; March-Leuba, Jose A [ORNL

2008-01-01

56

Centrifugal filter for catching dust  

Microsoft Academic Search

Possibilities are considered of using a test centrifugal filter for catching dust within which there is normally separation\\u000a of heterogeneous gas stream phases. The capture efficiency and hydraulic resistance of the test centrifugal filter are determined\\u000a by means of computer simulation. Results are provided for comparative industrial tests of a two-level centrifugal filter and\\u000a cyclone. An industrial example is demonstrated

D. A. Serebryanskii

2009-01-01

57

Theory of finite disturbances in a centrifugal compression system with a vaneless radial diffuser  

NASA Technical Reports Server (NTRS)

A previous small perturbation analysis of circumferential waves in circumferential compression systems, assuming inviscid flow, is shown to be consistent with observations that narrow diffusers are more stable than wide ones, when boundary layer displacement effect is included. The Moore-Greitzer analysis for finite strength transients containing both surge and rotating stall in axial machines is adapted for a centrifugal compression system. Under certain assumptions, and except for a new second order swirl, the diffuser velocity field, including resonant singularities, can be carried over from the previous inviscid linear analysis. Nonlinear transient equations are derived and applied in a simple example to show that throttling through a resonant value of flow coefficient must occur in a sudden surge-like drop, accompanied by a transient rotating wave. This inner solution is superseded by an outer surge response on a longer time scale. Surge may occur purely as result of circumferential wave resonance. Numerical results are shown for various parametric choices relating to throttle schedule and the characteristic slope. A number of circumferential modes considered simultaneously is briefly discussed.

Moore, F. K.

1990-01-01

58

Formal Theory of an Inhomogeneous Electron Gas  

Microsoft Academic Search

Hohenberg and Kohn have dealt with the ground state of an interacting electron gas in an external potential and show that there exists a universal functional of the electron density n(\\\\mbi{r}), G[n(\\\\mbi{r})], independent of an external potential. This functional plays a central role in a theory of inhomogeneous electron gas. In this paper, a formal theory for deriving the form

Yukio Osaka

1974-01-01

59

Brane Gas Cosmology, M-Theory and Little String Theory  

SciTech Connect

We generalize the Brane Gas Cosmological Scenario to M-theory degrees of freedom, namely M5 and M2 branes. Without brane intersections, the Brandenberger Vafa(BV) arguments applied to M-theory degrees of freedom generically predict a large 6 dimensional spacetime. We show that intersections of M5 and M2 branes can instead lead to a large 4 dimensional spacetime. One dimensional intersections in 11D is related to (2,0) little strings (LST) on NS5 branes in type IIA. The gas regime of membranes in M-theory corresponds to the thermodynamics of LST obtained from holography. We propose a mechanism whereby LST living on the worldvolume of NS5 (M5)-branes wrapping a five dimensional torus, annihilate most efficiently in 3+1 dimensions leading to a large 3+1 dimensional spacetime. We also show that this picture is consistent with the gas approximation in M-theory.

Alexander, Stephon

2003-02-06

60

Brane Gas Cosmology, M-theory and Little String Theory  

NASA Astrophysics Data System (ADS)

We generalize the Brane Gas Cosmological Scenario to M-theory degrees of freedom, namely M5 and M2 branes. Without brane intersections, the Brandenberger Vafa(BV) arguments applied to M-theory degrees of freedom generically predict a large 6 dimensional spacetime. We show that intersections of M5 and M2 branes can instead lead to a large 4 dimensional spacetime. One dimensional intersections in 11D is related to (2,0) little strings (LST) on NS5 branes in type IIA. The gas regime of membranes in M-theory corresponds to the thermodynamics of LST obtained from holography. We propose a mechanism whereby LST living on the worldvolume of NS5 (M5)-branes wrapping a five dimensional torus, annihilate most efficiently in 3+1 dimensions leading to a large 3+1 dimensional spacetime. We also show that this picture is consistent with the gas approximation in M-theory.

Alexander, Stephon H. S.

2003-10-01

61

Theory of the Inhomogeneous Electron Gas  

Microsoft Academic Search

In this thesis we present a physical interpretation for the local many-body (exchange-correlation) potential of Hohenberg-Kohn-Sham density-functional theory of the interacting inhomogeneous electron gas. Thus far this potential has been known only in terms of its mathematical definition as the functional derivative of the yet unknown exchange-correlation energy functional. We interpret the potential as the work done in moving an

Manoj Kumar Harbola

1990-01-01

62

Centrifugal pyrocontactor  

DOEpatents

A method for mixing and separating immiscible liquid salts and liquid metals in a centrifugal contractor. The method includes introducing the liquids into an annular mixing zone and intensely mixing the liquids using vertical vanes attached to a rotor cooperating with vertical baffles, a horizontal baffle, and bottom vanes attached to the contactor housing. The liquids enter the contactor in the range of 700-800 degrees Celsius. The liquids are separated in the rotor into a dense phase and a light phase which are discharged from the contactor.

Chow, Lorac S. (Willowbrook, IL); Leonard, Ralph A. (River Forest, IL)

1993-01-01

63

Centrifugal pyrocontactor  

DOEpatents

A method is described for mixing and separating immiscible liquid salts and liquid metals in a centrifugal contractor. The method includes introducing the liquids into an annular mixing zone and intensely mixing the liquids using vertical vanes attached to a rotor cooperating with vertical baffles, a horizontal baffle, and bottom vanes attached to the contactor housing. The liquids enter the contactor in the range of 700-800 degrees Celsius. The liquids are separated in the rotor into a dense phase and a light phase which are discharged from the contactor. 6 figures.

Chow, L.S.; Leonard, R.A.

1993-10-19

64

Centrifugal Compressor Aeroelastic Analysis Code  

NASA Technical Reports Server (NTRS)

Centrifugal compressors are very widely used in the turbomachine industry where low mass flow rates are required. Gas turbine engines for tanks, rotorcraft and small jets rely extensively on centrifugal compressors for rugged and compact design. These compressors experience problems related with unsteadiness of flowfields, such as stall flutter, separation at the trailing edge over diffuser guide vanes, tip vortex unsteadiness, etc., leading to rotating stall and surge. Considerable interest exists in small gas turbine engine manufacturers to understand and eventually eliminate the problems related to centrifugal compressors. The geometric complexity of centrifugal compressor blades and the twisting of the blade passages makes the linear methods inapplicable. Advanced computational fluid dynamics (CFD) methods are needed for accurate unsteady aerodynamic and aeroelastic analysis of centrifugal compressors. Most of the current day industrial turbomachines and small aircraft engines are designed with a centrifugal compressor. With such a large customer base and NASA Glenn Research Center being, the lead center for turbomachines, it is important that adequate emphasis be placed on this area as well. Currently, this activity is not supported under any project at NASA Glenn.

Keith, Theo G., Jr.; Srivastava, Rakesh

2002-01-01

65

Theory of a multistage light gas gun  

NASA Astrophysics Data System (ADS)

The theory of multistage kinetic energy transfer is applied to the acceleration of a light projectile in a light gas gun (LGG). It is argued that a better overall gun efficiency can be obtained if the kinetic energy 1/2M1V12 of the first piston is not directly transferred to the light projectile but proceeds via an intermediate stage transfer mediated by a second piston M2. Application of such a gun to satellite or robot craft launching is outlined as well as some new technological features in the gun design.

Linhart, J. G.; Cattani, F.

2007-10-01

66

Centrifugal Adsorption Cartridge System  

NASA Technical Reports Server (NTRS)

The centrifugal adsorption cartridge system (CACS) is an apparatus that recovers one or more bioproduct(s) from a dilute aqueous solution or suspension flowing from a bioreactor. The CACS can be used both on Earth in unit gravity and in space in low gravity. The CACS can be connected downstream from the bioreactor; alternatively, it can be connected into a flow loop that includes the bioreactor so that the liquid can be recycled. A centrifugal adsorption cartridge in the CACS (see figure) includes two concentric cylinders with a spiral ramp between them. The volume between the inner and outer cylinders, and between the turns of the spiral ramp is packed with an adsorbent material. The inner cylinder is a sieve tube covered with a gas-permeable, hydrophobic membrane. During operation, the liquid effluent from the bioreactor is introduced at one end of the spiral ramp, which then constrains the liquid to flow along the spiral path through the adsorbent material. The spiral ramp also makes the flow more nearly uniform than it would otherwise be, and it minimizes any channeling other than that of the spiral flow itself. The adsorbent material is formulated to selectively capture the bioproduct(s) of interest. The bioproduct(s) can then be stored in bound form in the cartridge or else eluted from the cartridge. The centrifugal effect of the spiral flow is utilized to remove gas bubbles from the liquid. The centrifugal effect forces the bubbles radially inward, toward and through the membrane of the inner cylinder. The gas-permeable, hydrophobic membrane allows the bubbles to enter the inner cylinder while keeping the liquid out. The bubbles that thus enter the cylinder are vented to the atmosphere. The spacing between the ramps determines rate of flow along the spiral, and thereby affects the air-bubble-removal efficiency. The spacing between the ramps also determines the length of the fluid path through the cartridge adsorbent, and thus affects the bioproduct-capture efficiency of the cartridge. Depending on the application, several cartridges could be connected in a serial or parallel flow arrangement. A parallel arrangement can be used to increase product-capturing and flow capacities while maintaining a low pressure drop. A serial arrangement can be used to obtain high product-capturing capacity; alternatively, series-connected cartridges can be packed with different adsorbents to capture different bioproducts simultaneously.

Gonda, Steve R.; Tsao, Yow-Min D.; Lee, Wenshan

2004-01-01

67

The Maryland Centrifugal Experiment (MCX) has been built to study the confinement of supersonically-rotating plasmas and velocity shear stabilization of MHD instabilities. Theory  

E-print Network

ABSTRACT The Maryland Centrifugal Experiment (MCX) has been built to study the confinement the MCX centrifugal confinement scheme are presented here with the data and analysis from its first nine that this centrifugal confinement scheme provides good stability and confinement at the temperatures and densities under

Anlage, Steven

68

Perfect gas effects in compressible rapid distortion theory  

NASA Technical Reports Server (NTRS)

The governing equations presented for small amplitude unsteady disturbances imposed on steady, compressible mean flows that are two-dimensional and nearly uniform have their basis in the perfect gas equations of state, and therefore generalize previous results based on tangent gas theory. While these equations are more complex, this complexity is required for adequate treatment of high frequency disturbances, especially when the base flow Mach number is large; under such circumstances, the simplifying assumptions of tangent gas theory are not applicable.

Kerschen, E. J.; Myers, M. R.

1987-01-01

69

Centrifuging a Sample  

NSDL National Science Digital Library

The demonstration on this page shows a technique that should not be used by undergraduate chemistry laboratory. This video shows what happens to sample in a centrifuge while the centrifuge is on, and the result of stopping the centrifuge improperly. A narrative is included in this video: The centrifuging process allows the solvent to completely settle out. The jarring caused by hand braking destroys the distinct separation between supernatant and solid.

70

Brane gas cosmology in M theory: Late time behavior  

Microsoft Academic Search

We investigate the late-time behavior of a universe containing a supergravity gas and wrapped 2-branes in the context of M theory compactified on T10. The supergravity gas tends to drive uniform expansion, while the branes impede the expansion of the directions about which they are wrapped. Assuming spatial homogeneity, we study the dynamics both numerically and analytically. At late times

Richard Easther; Brian R. Greene; Mark G. Jackson; Daniel Kabat

2003-01-01

71

USE OF MAILBOX APPROACH, VIDEO SURVEILLANCE, AND SHORT-NOTICE RANDOM INSPECTIONS TO ENHANCE DETECTION OF UNDECLARED LEU PRODUCTION AT GAS CENTRIFUGE ENRICHMENT PLANTS.  

SciTech Connect

Current safeguards approaches used by the IAEA at gas centrifuge enrichment plants (GCEPs) need enhancement in order to detect undeclared LEU production with adequate detection probability. ''Mailbox'' declarations have been used in the last two decades to verify receipts, production, and shipments at some bulk-handling facilities (e.g., fuel-fabrication plants). The operator declares the status of his plant to the IAEA on a daily basis using a secure ''Mailbox'' system such as a secure tamper-resistant computer. The operator agrees to hold receipts and shipments for a specified period of time, along with a specified number of annual inspections, to enable inspector access to a statistically large enough population of UF{sub 6} cylinders and fuel assemblies to achieve the desired detection probability. The inspectors can access the ''Mailbox'' during randomly timed inspections and then verify the operator's declarations for that day. Previously, this type of inspection regime was considered mainly for verifying the material balance at fuel-fabrication, enrichment, and conversion plants. Brookhaven National Laboratory has expanded the ''Mailbox'' concept with short-notice random inspections (SNRIs), coupled with enhanced video surveillance, to include declaration and verification of UF{sub 6} cylinder operational data to detect activities associated with undeclared LEU production at GCEPs. Since the ''Mailbox'' declarations would also include data relevant to material-balance verification, these randomized inspections would replace the scheduled monthly interim inspections for material-balance purposes; in addition, the inspectors could simultaneously perform the required number of Limited-Frequency Unannounced Access (LFUA) inspections used for HEU detection. This approach would provide improved detection capabilities for a wider range of diversion activities with not much more inspection effort than at present.

BOYER, B.D.; GORDON, D.M.; JO, J.

2006-07-16

72

Centrifuges MicrocentrifugesMicrocentrifuges  

E-print Network

Operator errorOperator error 2.8 #12;Centrifuges ­Safety Tip Always remember to balance the centrifuge sets of tubes, buckets etc. 3. Tightly seal all tubes and safety cups. 4. Ensure that rotor is locked spills or breakage's § Lubricate O-rings and rotor threads weekly § Do not use rotors that have been

Collins, Gary S.

73

Centrifuges Biological Safety  

E-print Network

centrifuges go fast enough to pose dangers. Mechanical hazards can include stress to the rotor metal, fatigue, corrosion, and container selection. It is normally one of these things, or an improperly balanced load - Check that the rotor is compatible with your centrifuge, avoid incompatible chemicals, use proper tubes

Pawlowski, Wojtek

74

Attack on centrifugal costs  

Microsoft Academic Search

The Monsanto Chocolate Bayou plant has had an aggressive and successful energy conservation program. The combined efforts have resulted in a 80% reduction in unit energy consumption compared to 1972. The approach of using system audits to optimize fluid systems was developed. Since most of the fluid movers are centrifugal, the name Centrifugal Savings Task Force was adopted. There are

1986-01-01

75

Lattice gas hydrodynamics: Theory and simulations  

SciTech Connect

The first successful application of a microscopic analogy to create a skeleton cellular automaton and analyze it with statistical mechanical tools, was the work of Frisch, Hasslacher and Pomeau on the Navier-Stokes equation in two and three dimensions. This has become a very large research area with lattice gas models and methods being used for both fundamental investigations into the foundations of statistical mechanics and a large number of diverse applications. This present research was devoted to enlarging the fundamental scope of lattice gas models and proved successful. Since the beginning of this proposal, cellular automata have been constructed for statistical mechanical models, fluids, diffusion and shock systems in fundamental investigations. In applied areas, there are now excellent lattice gas models for complex flows through porous media, chemical reaction and combustion dynamics, multiphase flow systems, and fluid mixtures with natural boundaries. With extended cellular fluid models, one can do problems with arbitrary pairwise potentials. Recently, these have been applied to such problems as non-newtonian or polymeric liquids and a mixture of immiscible fluids passing through fractal or spongelike media in two and three dimensions. This proposal has contributed to and enlarged the scope of this work.

Hasslacher, B.

1993-01-01

76

Lattice gas hydrodynamics: Theory and simulations  

SciTech Connect

The first successful application of a microscopic analogy to create a skeleton cellular automaton and analyze it with statistical mechanical tools, was the work of Frisch, Hasslacher and Pomeau on the Navier-Stokes equation in two and three dimensions. This has become a very large research area with lattice gas models and methods being used for both fundamental investigations into the foundations of statistical mechanics and a large number of diverse applications. This present research was devoted to enlarging the fundamental scope of lattice gas models and proved quite successful. Since the beginning of this proposal, cellular automata have been constructed for statistical mechanical models, fluids, diffusion and shock systems in fundamental investigations. In applied areas, there are now excellent lattice gas models for complex flows through porous media, chemical reaction and combustion dynamics, multiphase flow systems, and fluid mixtures with natural boundaries. With extended cellular fluid models, one can do problems with arbitrary pairwise potentials. Recently, these have been applied to such problems as non-newtonian or polymeric liquids and a mixture of immiscible fluids passing through fractal or spongelike media in two and three dimensions. This proposal has contributed to and enlarged the scope of this work.

Hasslacher, B.

1993-01-01

77

Dry seal applications in centrifugal compressors  

SciTech Connect

Most centrifugal compressors in refineries and petrochemical plants use shaft end seals which are either controlled leakage labyrinths (nontoxic/nonhazardous fluids only) or some type of fluid film seals using a liquid, primarily oil, as a barrier fluid. This article discusses the emerging technology of so-called dry seals. These seals use gas as the sealing fluid medium, and control the leakage to very low levels by limiting clearances between the rotating and stationary faces. Dry gas seal technology has progressed to where it can be applied to most centrifugal process compressors. The benefits and application considerations are presented.

Fischbach, M.J. (M.W. Kellogg Co., Houston, TX (US))

1989-10-01

78

Defining the needs for non-destructive assay of UF6 feed, product, and tails at gas centrifuge enrichment plants and possible next steps  

SciTech Connect

Current safeguards approaches used by the IAEA at gas centrifuge enrichment plants (GCEPs) need enhancement in order to detect undeclared LEU production with adequate detection probability using non destructive assay (NDA) techniques. At present inspectors use attended systems, systems needing the presence of an inspector for operation, during inspections to verify the mass and {sup 235}U enrichment of UF{sub 6} bulk material used in the process of enrichment at GCEPS. The inspectors also take destructive assay (DA) samples for analysis off-site which provide accurate, on the order of 0.1 % to 0.5% uncertainty, data on the enrichment of the UF{sub 6} feed, tails, and product. However, DA sample taking is a much more labor intensive and resource intensive exercise for the operator and inspector. Furthermore, the operator must ship the samples off-site to the IAEA laboratory which delays the timeliness of the results and contains the possibility of the loss of the continuity of knowledge of the samples during the storage and transit of the material. Use of the IAEA's inspection sampling algorithm shows that while total sample size is fixed by the total population of potential samples and its intrinsic qualities, the split of the samples into NDA or DA samples is determined by the uncertainties in the NDA measurements. Therefore, the larger the uncertainties in the NDA methods, more of the sample taken must be DA samples. Since the DA sampling is arduous and costly, improvements in NDA methods would reduce the number of DA samples needed. Furthermore, if methods of on-site analysis of the samples could be developed that have uncertainties in the 1-2% range, a lot of the problems inherent in DA sampling could be removed. The use of an unattended system that could give an overview of the entire process giving complementary data on the enrichment process as well as accurate measures of enrichment and weights of the UF{sub 6} feed, tails, and product would be a major step in enhancing the ability of NDA beyond present attended systems. The possibility of monitoring the feed, tails, and product header pipes in such a way as to gain safeguards relevant flow and enrichment information without compromising the intellectual property of the operator including proprietary equipment and operational parameters would be a huge step forward. This paper contains an analysis of possible improvements in unattended and attended NDA systems including such process monitoring and possible on-site analysis of DA samples that could reduce the uncertainty of the inspector measurements reducing the difference between the operator's and inspector's measurements providing more effective and efficient IAEA GeEPs safeguards.

Boyer, Brian D [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Moran, Bruce W [IAEA; Lebrun, Alain [IAEA

2009-01-01

79

Brane gas cosmology in M-theory: late time behavior  

Microsoft Academic Search

We investigate the late-time behavior of a universe containing a supergravity gas and wrapped 2-branes in the context of M-theory compactified on T 10. The supergravity gas tends to drive uniform expansion, while the branes impede the expansion of the directions about which they are wrapped. As- suming spatial homogeneity, we study the dynamics both numerically and analytically. At late

Richard Easther; Brian R. Greeneab; Mark G. Jackson; Daniel Kabatc

80

COLLISIONLESS ELECTRON HEATING IN RF GAS DISCHARGES: I. QUASILINEAR THEORY  

E-print Network

parameters. Due to the large value of the mean free path (MFP) the main mechanism of electron heating turnsCOLLISIONLESS ELECTRON HEATING IN RF GAS DISCHARGES: I. QUASILINEAR THEORY Yu.M. Aliev1 , I an interest in mechanisms of electron heating and power deposition in the plasma main- tained by radio

Kaganovich, Igor

81

Inhomogeneous electron gas theory of molecular dissociation energies  

Microsoft Academic Search

By separating the total energy of atoms and diatomic molecules into the sum of Thomas-Fermi, density gradient and exchange energies, the dissociation energy D, divided by the square of the total number of electrons in the molecule, is related by a simple analytic formula to the inhomogeneity kinetic energy of electron gas theory, for the equilibrium molecule. The shape of

N. H. March

1991-01-01

82

Centrifuges Replacement Study Proposal  

E-print Network

the dense product from slurry by dewatering or washing cycles. Specifications: Manufacturer: Ametek (process equipment division) Type: Tolhurst 48? X 30? Quick-Dismantle Basket Type Centrifuge Basket Diameter 48" Basket RPM 1080 Basket Depth 30...-liquid mixture to be separated is processed by the Distribution, Intermediate dewatering, Washing, Final dewatering, and Solid discharge operations. These operations are processed in the centrifuge successively and at the same place. 7 Figure below shows...

Iqbal, Muhammad

2005-12-16

83

Dry seal applications in centrifugal compressors  

Microsoft Academic Search

Most centrifugal compressors in refineries and petrochemical plants use shaft end seals which are either controlled leakage labyrinths (nontoxic\\/nonhazardous fluids only) or some type of fluid film seals using a liquid, primarily oil, as a barrier fluid. This article discusses the emerging technology of so-called dry seals. These seals use gas as the sealing fluid medium, and control the leakage

Fischbach

1989-01-01

84

Theory of multicolor lattice gas - A cellular automaton Poisson solver  

NASA Technical Reports Server (NTRS)

The present class of models for cellular automata involving a quiescent hydrodynamic lattice gas with multiple-valued passive labels termed 'colors', the lattice collisions change individual particle colors while preserving net color. The rigorous proofs of the multicolor lattice gases' essential features are rendered more tractable by an equivalent subparticle representation in which the color is represented by underlying two-state 'spins'. Schemes for the introduction of Dirichlet and Neumann boundary conditions are described, and two illustrative numerical test cases are used to verify the theory. The lattice gas model is equivalent to a Poisson equation solution.

Chen, H.; Matthaeus, W. H.; Klein, L. W.

1990-01-01

85

Shale Gas Production Theory and Case Analysis We researched the process of oil recovery and shale gas  

E-print Network

Shale Gas Production Theory and Case Analysis (Siemens) We researched the process of oil recovery and shale gas recovery and compare the difference between conventional and unconventional gas reservoir and recovery technologies. Then we did theoretical analysis on the shale gas production. According

Ge, Zigang

86

Centrifugal Separation and Equilibration Dynamics in an Electron-Antiproton Plasma G. B. Andresen,1  

E-print Network

Centrifugal Separation and Equilibration Dynamics in an Electron-Antiproton Plasma G. B. Andresen,1 radially by mass, forming centrifugally separated states. Here, we report the first detailed measurements centrifugally separated system. While the observed equilibrium states are expected and in agreement with theory

Fajans, Joel

87

Energy recuperation centrifuge  

SciTech Connect

Centrifuge comprising two drums having coaxial horizontal axes. The inner drum carries a set of dishes and, on the periphery, a scraper screw. A sludge chamber is provided at one end of the outer drum and, by way of passages adapted to be closed by a discharge device, is in communication with the outside. The centrifuge is provided with a double energy recuperation device comprising a centripetal wheel and a ring of ejectors fastened to the inner drum, together with blading fixed opposite the ejectors. The ejectors are so directed that the absolute speed of the fluid leaving the centrifuge is low. The discharge device comprises an overflow continuously fed in order to hold, by pressure, a movable plate in the closed position in front of the passages.

Schlegel, R. F.; Bourassin, R. P.; Laparetre, M. A.

1985-04-02

88

Attack on centrifugal costs  

SciTech Connect

The Monsanto Chocolate Bayou plant has had an aggressive and successful energy conservation program. The combined efforts have resulted in a 80% reduction in unit energy consumption compared to 1972. The approach of using system audits to optimize fluid systems was developed. Since most of the fluid movers are centrifugal, the name Centrifugal Savings Task Force was adopted. There are three tools that are particularly valuable in optimizing fluid systems. First, a working level understanding of the Affinity Laws seems a must. In addition, the performance curves for the fluid movers is needed. The last need is accurate system field data. Systems effectively managed at the Chocolate Bayou plant were process air improvement, feed-water pressure reduction, combustion air blower turbine speed control, and cooling tower pressure reduction. Optimization of centrifugal systems is an often-overlooked opportunity for energy savings. The basic guidelines are to move only the fluid needed, and move it at as low a pressure as possible.

Murray, P.F.

1986-03-01

89

Effective field theory approach to string gas cosmology  

NASA Astrophysics Data System (ADS)

We derive the 4D low energy effective field theory for a closed string gas on a time dependent FRW background. We examine the solutions and find that although the Brandenberger Vafa mechanism at late times no longer leads to radion stabilization, the radion rolls slowly enough that the scenario is still of interest. In particular, we find a simple example of the string inspired dark matter recently proposed by Gubser and Peebles.

Battefeld, Thorsten; Watson, Scott

2004-06-01

90

Brane gas cosmology in M theory: Late time behavior  

Microsoft Academic Search

We investigate the late-time behavior of a universe containing a supergravity\\u000agas and wrapped 2-branes in the context of M-theory compactified on T^10. The\\u000asupergravity gas tends to drive uniform expansion, while the branes impede the\\u000aexpansion of the directions about which they are wrapped. Assuming spatial\\u000ahomogeneity, we study the dynamics both numerically and analytically. At late\\u000atimes the

Richard Easther; Brian R. Greene; Mark G. Jackson; Daniel Kabat

2003-01-01

91

On the quantum field theory of the inhomogeneous electron gas  

Microsoft Academic Search

The equilibrium properties of an inhomogeneous gas of interacting fermions are derived using methods of finite temperature quantum field theory. A Landau-type quasiparticle spectrum yielding the exact ground state energy or, at finite temperatures, the exact thermodynamic potential is constructed from the g-Hartree equations. The heat kernel expansion of Schrödinger operators is then used to express the Hohenberg-Kohn density functional

K. Dietz; G. Weymans

1985-01-01

92

Centrifugal projectile launchers  

NASA Astrophysics Data System (ADS)

The concept of a centrifugal projectile launcher as an alternative to both chemical and electromagnetic launchers for anti-tank and air defence systems is discussed. It is shown that centrifugal projectile launchers can provide reliable, efficient, compact systems that will accelerate projectiles to 2-3 km/s with energies up to one megajoule. State-of-the-art composite rotors can be modified to launch projectiles of tens of grams to the order of 1 km/s. A demonstration rotor with reasonable energy density can be designed to accelerate 60 gram projectiles to 3 km/s repetitively.

Felber, F. S.

1982-01-01

93

Bifurcated equilibria in centrifugally confined plasma  

SciTech Connect

A bifurcation theory and associated computational model are developed to account for abrupt transitions observed recently on the Maryland Centrifugal eXperiment (MCX) [R. F. Ellis et al. Phys. Plasmas 8, 2057 (2001)], a supersonically rotating magnetized plasma that relies on centrifugal forces to prevent thermal expansion of plasma along the magnetic field. The observed transitions are from a well-confined, high-rotation state (HR-mode) to a lower-rotation, lesser-confined state (O-mode). A two-dimensional time-dependent magnetohydrodynamics code is used to simulate the dynamical equilibrium states of the MCX configuration. In addition to the expected viscous drag on the core plasma rotation, a momentum loss term is added that models the friction of plasma on the enhanced level of neutrals expected in the vicinity of the insulators at the throats of the magnetic mirror geometry. At small values of the external rotation drive, the plasma is not well-centrifugally confined and hence experiences the drag from near the insulators. Beyond a critical value of the external drive, the system makes an abrupt transition to a well-centrifugally confined state in which the plasma has pulled away from the end insulator plates; more effective centrifugal confinement lowers the plasma mass near the insulators allowing runaway increases in the rotation speed. The well-confined steady state is reached when the external drive is balanced by only the viscosity of the core plasma. A clear hysteresis phenomenon is shown.

Shamim, I.; Teodorescu, C.; Guzdar, P. N.; Hassam, A. B.; Clary, R.; Ellis, R.; Lunsford, R. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States)

2008-12-15

94

Lightweight Shield for Centrifuge  

NASA Technical Reports Server (NTRS)

Centrifuge bowl composed of laminated aluminum offers required combination of high strength at reduced weight. Around outside wall of bowl core of 1/16 inch thick spun aluminum are wrapped two layers of aluminum, each also one-sixteenth inch thick. Layered structure prevents cracks from propagating through wall.

Luper, C.

1982-01-01

95

Pendulums and Centrifuges Materials  

E-print Network

Pendulums and Centrifuges Materials: · String · Washers · Stop Watch · Bucket · Measuring is a pendulum? Can you think of an example of something that uses a pendulum? (clock) Procedure: · Cut it will be. Pull the pendulum back about 40 to 50 cm, and let go while someone starts the stop watch. How

Benitez-Nelson, Claudia

96

3, 731768, 2006 Centrifuge modeling  

E-print Network

HESSD 3, 731­768, 2006 Centrifuge modeling of one-step tests H. Nakajima and A. T. Stadler Title are under open-access review for the journal Hydrology and Earth System Sciences Centrifuge modeling of one­768, 2006 Centrifuge modeling of one-step tests H. Nakajima and A. T. Stadler Title Page Abstract

Paris-Sud XI, Université de

97

Next Generation Safeguards Initiative: Analysis of Probability of Detection of Plausible Diversion Scenarios at Gas Centrifuge Enrichment Plants Using Advanced Safeguards  

SciTech Connect

Over the last decade, efforts by the safeguards community, including inspectorates, governments, operators and owners of centrifuge facilities, have given rise to new possibilities for safeguards approaches in enrichment plants. Many of these efforts have involved development of new instrumentation to measure uranium mass and uranium-235 enrichment and inspection schemes using unannounced and random site inspections. We have chosen select diversion scenarios and put together a reasonable system of safeguards equipment and safeguards approaches and analyzed the effectiveness and efficiency of the proposed safeguards approach by predicting the probability of detection of diversion in the chosen safeguards approaches. We analyzed the effect of redundancy in instrumentation, cross verification of operator instrumentation by inspector instrumentation, and the effects of failures or anomalous readings on verification data. Armed with these esults we were able to quantify the technical cost benefit of the addition of certain instrument suites and show the promise of these new systems.

Hase, Kevin R. [Los Alamos National Laboratory; Hawkins Erpenbeck, Heather [Los Alamos National Laboratory; Boyer, Brian D. [Los Alamos National Laboratory

2012-07-10

98

Brane gas cosmology in M theory: Late time behavior  

NASA Astrophysics Data System (ADS)

We investigate the late-time behavior of a universe containing a supergravity gas and wrapped 2-branes in the context of M theory compactified on T10. The supergravity gas tends to drive uniform expansion, while the branes impede the expansion of the directions about which they are wrapped. Assuming spatial homogeneity, we study the dynamics both numerically and analytically. At late times the radii obey power laws which are determined by the brane wrapping numbers, leading to interesting hierarchies of scale between the wrapped and unwrapped dimensions. The biggest hierarchy that could evolve from an initial thermal fluctuation produces three large unwrapped dimensions. We also study configurations corresponding to string winding, in which the M2-branes are all wrapped around the (small) 11th dimension, and show that this recovers the scenario discussed by Brandenberger and Vafa.

Easther, Richard; Greene, Brian R.; Jackson, Mark G.; Kabat, Daniel

2003-06-01

99

Centrifugal unbalance detection system  

SciTech Connect

A system consisting of an accelerometer sensor attached to a centrifuge enclosure for sensing vibrations and outputting a signal in the form of a sine wave with an amplitude and frequency that is passed through a pre-amp to convert it to a voltage signal, a low pass filter for removing extraneous noise, an A/D converter and a processor and algorithm for operating on the signal, whereby the algorithm interprets the amplitude and frequency associated with the signal and once an amplitude threshold has been exceeded the algorithm begins to count cycles during a predetermined time period and if a given number of complete cycles exceeds the frequency threshold during the predetermined time period, the system shuts down the centrifuge.

Cordaro, Joseph V. (Martinez, GA); Reeves, George (Graniteville, SC); Mets, Michael (Aiken, SC)

2002-01-01

100

Centrifugally decoupling touchdown bearings  

DOEpatents

Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

Post, Richard F

2014-06-24

101

The vacuum arc centrifuge  

NASA Astrophysics Data System (ADS)

The separation of elements and isotopes by means of rotating magnetized plasma columns using a laser-triggered vacuum arc centrifuge is described. This vacuum arc centrifuge is sustained by the erosion and ionization of the cathode material, thus producing relatively pure, highly ionized, rotating plasma columns of the cathode material. Any solid metal, or mixture of metals, can be converted into plasma, and the constituent isotopes partially separated in the centrifuge, by fabricating the arc cathode out of the desired metals. The device also offers the possibility of operation with nonconducting solid elements or compounds by imbedding the desired substance in a conducting matrix. A wide variety of metals and combinations of metals were studied, ranging from C through Cu to Cd/Sn. Typical angular rotation frequencies of approx. 100,000 rad/sec were measured, with concomitant enrichments up to a factor of two for Cu 65. The device in its present form is not a viable source of partially enriched stable isotopes at a competitive cost.

Krishnan, M.; Hirshfield, J. L.

102

Sharp nonlinear stability for centrifugal filtration convection in magnetizable media  

NASA Astrophysics Data System (ADS)

A nonlinear stability theory is adopted to study centrifugal thermal convection in a magnetic-fluid-saturated and differentially heated porous layer placed in a zero-gravity environment. The axis of rotation of the layer is placed within its boundaries that leads to an alternating direction of the centrifugal body force. An analysis through the variational principles is made to find the unconditional and sharp nonlinear limits. The compound matrix method is employed to solve the eigenvalue problems of the nonlinear and corresponding linear theories. The importance of nonlinear theory is established by demonstrating the failure of the linear theory in capturing the physics of the onset of convection.

Saravanan, S.; Brindha, D.

2011-11-01

103

Experimental research on mass transfer in a centrifugal fluidized bed dryer  

SciTech Connect

The influences of bed thickness, particle diameter, rotating speed of the basket and operating gas velocity on the mass transfer between gas and particles in the centrifugal fluidized bed dryer (CFBD) were examined. The experimental correlation used to calculate the mass transfer coefficient in the centrifugal fluidized bed dryer was obtained.

Chen, G.F.; Wang, W.; Yan, H.; Wang, X.Z.

1999-10-01

104

Lattice-gas model in kinetic theory of gas-solid interface processes  

NASA Astrophysics Data System (ADS)

The improvement of the experimental methods for investigating surface processes changes the existing ideas about the role of the different factors of the gas-solid system and the mechanisms of the processes. The recent studies have confirmed the conception of surface processes as the ones taking place in the condensed phases. At the same time, the surface processes generally are described by fairly rough models based on the law of mass action, which is true of the ideal systems. The contradiction is eliminated to a certain degree when a lattice-gas model which takes into account the proper volume of the adspecies and adspecies interaction is used. On this basis it is easy to consider the effect of the local environment on the activation barrier of an elementary process. This enables one to apply it extensively to be the atomic-molecular processes associated with a change in the spatial arrangement of the adspecies and their chemical conversion. The review describes the development of the kinetic theory of the surface processes at the gas-solid interface using on the lattice-gas model and its modern modifications. Applications of the theory to the adsorption-desorption processes and the catalytic reactions are considered. The reaction rates in the condensed phases and the role of the correlation effects of the interacting adspecies and the distribution of the system's components are described. The lattice-gas model helps us explain the empirical principles of the adsorption processes; a variable order of desorption rate; the splitting of the thermodesorption spectra on the homogeneous surfaces; an increase in the sticking coefficient with coverage at its small values; phase transitions in the adlayers and their effect on the adsorption-desorption rate and the diffusion coefficients; a great mutual effect of the adspecies of the different kinds on the rate of the elementary processes; the dependence of the course of a process on the conditions in which the initial surface coverages are formed; multiplicity of the steady states of the reaction systems and the isothermal oscillation conditions of the reaction mode; etc. At present the theory of surface processes enables one to take into account a wide range of the real properties of the gas-solid system: the lateral interaction between the adspecies and their phase transitions, surface inhomogeneity, a limited mobility of the adspecies and the solid body surface atoms, the rearrangement of the subsurface solid region and so on. The joint influence of the factors mentioned above are also taken into account. Theoretical results are compared with the numerical calculations by the Monte Carlo methods.

Tovbin, Yu. K.

105

The Magnetic Centrifugal Mass Filter  

SciTech Connect

Mass filters using rotating plasmas have been considered for separating nuclear waste and spent nuclear fuel. We propose a new mass filter that utilizes centrifugal and magnetic confinement of ions in a way similar to the asymmetric centrifugal trap. This magnetic centrifugal mass filter is shown to be more proliferation resistant than present technology. This filter is collisional and produces well confined output streams, among other advantages. __________________________________________________

Abraham J. Fetterman and Nathaniel J. Fisch

2011-08-04

106

National geotechnical centrifuge  

NASA Astrophysics Data System (ADS)

A high G-ton centrifuge, able to take a 2700 kg (6000 lb) payload up to 300 G, is described. The stability of dams and embankments, the bearing capacity of soil foundations, and the dynamic behavior of foundations due to vibration of machinery are examples of applications. A power rating of 6,000 kW (9,000 hp) was established for the motor. An acceptable maximum speed of 70 rpm was determined. A speed increase with a ratio of 1:3 is discussed. The isolated tension straps, the anti-spreader bar and the flexwall bucket, and safety precautions are also discussed.

Hallam, J. A.; Kunz, N.; Vallotton, W. C.

1982-05-01

107

Centrifugal Filter Devices Centricon centrifugal filter devices with 10,000 NMWL, 30,000 NMWL,  

E-print Network

CENTRICON ® Centrifugal Filter Devices User Guide Centricon centrifugal filter devices with 10-vitro diagnostic use. Centricon centrifugal filter devices with 3,000 NMWL Ultracel YM membranes are for research ................................................... 3 Maximum Centrifugal Force .............................................................. 3 Rotor

Kirschner, Marc W.

108

Design and Performance Analysis of Centrifugal Pump  

Microsoft Academic Search

This paper deals with the design and performance analysis of centrifugal pump. In this paper, centrifugal pump is analyzed by using a single-stage end suction centrifugal pump. Two main components of a centrifugal pump are the impeller and the casing. The impeller is a rotating component and the casing is a stationary component. In centrifugal pump, water enters axially through

Khin Cho Thin; Mya Mya Khaing; Khin Maung Aye

2008-01-01

109

Centrifugal shot blast system  

SciTech Connect

This report describes a demonstration of Concrete cleaning, Inc., modified centrifugal shot blast technology to remove the paint coating from concrete flooring. This demonstration is part of the Chicago Pile-5 (CP-5) Large-Scale Demonstration Project (LSDP) sponsored by the US Department of Energy (DOE), office of Science and Technology (OST), Deactivation and Decommissioning Focus Area (DDFA). The objective of the LSDP is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East (ANL) CP-5 Research Reactor. The purpose of the LSDP is to demonstrate that using innovative and improved decontamination and decommissioning (D and D) technologies from various sources can result in significant benefits, such as decreased cost and increased health and safety, as compared with baseline D and D technologies. Potential markets exist for the innovative centrifugal shot blast system at the following sites: Fernald Environmental Management Project, Los Alamos, Nevada, Oak Ridge Y-12 and K-25, Paducah, Portsmouth Gaseous Diffusion site, and the Savannah River Site. This information is based on a revision to the OST Linkage Tables dated August 4, 1997.

NONE

1998-02-01

110

Effect of inner ring centrifugal displacement on the dynamic characteristics of high-speed angular contact ball bearing  

Microsoft Academic Search

According to the elastic theory the calculating formulas of inner ring centrifugal displacement are inferred, in consideration of inner ring centrifugal displacement the basic equations of angular contact ball bearing are set up, effect of inner ring centrifugal displacement on the dynamic characteristics of high-speed angular contact ball bearings are studied. The results from taking 7012C bearing as an example

Wang Bao-min; Mei Xue-song; Hu Chi-bing; Wu Zai-xin

2010-01-01

111

Performance of a centrifugal phytotron  

Microsoft Academic Search

It is possible to cultivate plants under an artificial gravity field generated by a centrifugal device in space. In order to determine an optimal magnitude of gravity, there is a need to investigate the relationship between plant growth and gravity, including not only reduced gravity but also gravity greater than 1G. A prototype centrifugal phytotron was designed and fabricated in

A. Tani; Y. Nishiura; M. Kiyota; H. Murase; N. Honami; I. Aiga

1996-01-01

112

A New Centrifugal Ultrafiltration Device  

Microsoft Academic Search

A novel ultrafiltration device is described. It consists of a vertical dialysis cell in which the semipermeable membrane is supported by a metal or plastic porous, rigid sheet. The dialysis cell is mounted in a centrifuge swinging bucket, or rotor hole, with the membrane parallel to the centrifuge radius. Experiments are performed by filling one dialysis cell compartment with the

Suzana Pereira Nunes; Ana Adelina Winkler-hechenleitner; Fernando Galembeck

1986-01-01

113

Centrifuge treatment of coal tar  

SciTech Connect

New technology is required for the removal of water and heavy fractions from regular coal tar. Centrifuges offer the best option. Purification of coal tar by means of centrifuges at OAO NLMK permits the production of pitch coke or electrode pitch that complies with current standards.

L.A. Kazak; V.Z. Kaidalov; L.F. Syrova; O.S. Miroshnichenko; A.S. Minakov [Giprokoks, the State Institute for the Design of Coke-Industry Enterprises, Kharkov (Ukraine)

2009-07-15

114

21 CFR 864.5350 - Microsedimentation centrifuge.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Microsedimentation centrifuge. 864.5350 Section 864.5350... § 864.5350 Microsedimentation centrifuge. (a) Identification. A microsedimentation centrifuge is a device used to sediment red...

2010-04-01

115

21 CFR 864.5350 - Microsedimentation centrifuge.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Microsedimentation centrifuge. 864.5350 Section 864.5350... § 864.5350 Microsedimentation centrifuge. (a) Identification. A microsedimentation centrifuge is a device used to sediment red...

2011-04-01

116

Rat growth during chronic centrifugation  

NASA Technical Reports Server (NTRS)

Female weanling rats were chronically centrifuged at 4.15 G with controls at terrestrial gravity. Samples were sacrificed for body composition studies at 0, 28, 63, 105 and 308 days of centrifugation. The centrifuged group approached a significantly lower mature body mass than the controls (251 and 318g) but the rate of approach was the same in both groups. Retirement to 1G on the 60th day resulted in complete recovery. Among individual components muscle, bone, skin, CNS, heart, kidneys, body water and body fat were changed in the centrifuged group. However, an analysis of the growth of individual components relative to growth of the total fat-free compartment revealed that only skin (which increased in mass) was responding to centrifugation per se.

Pitts, G. C.; Oyama, J.

1978-01-01

117

Control of Centrifugal Instabilities  

NASA Astrophysics Data System (ADS)

Recent experiments(Weisberg, Kevrekidis & Smits (1997) J. Fluid Mech.), 348, 141--151. have demonstrated that the centrifugal instability leading to Taylor vortex flow can be controlled by harmonic oscillations of the inner cylinder in the axial direction. Over a wide range of frequencies and amplitudes of this oscillation, (linear) Floquet analysis(Marques & Lopez (1997) J. Fluid Mech.), 348, 153--175. describes the observed control of the instability; the dynamics remain axisymmetric and the response to the applied periodic control mechanism is syncronous. However, for large amplitudes of oscillations with small frequencies, the response is neither axisymmetric nor synchronous, and competition between different azimuthal and axial modes is important. Here, we present some further Floquet analysis in the parameter regime where experimentally the onset is to ``wobbly'' Taylor cells. As well, some initial nonlinear results are presented, examining the singular nature of the frequency going to zero limit.

Lopez, J. M.; Marques, F.; Shen, Jie

1997-11-01

118

Open-cycle centrifugal vapor-compression heat pump  

NASA Astrophysics Data System (ADS)

The objectives of the program were: (1) to develop an open cycle, high lift, centrifugal steam compressor system that can be efficiently retrofitted to existing multi-effect and high temperature differential evaporators while maintaining the cost benefits of a single stage centrifugal compressor, and (2) to demonstrate the energy saving cost benefits of driving the compressor with a natural gas fueled gas turbine engine. The turbine exhaust was to be used for final drying of the product that was evaporated. The installation of the system is described along with the test activities through May 1987.

Burgmeier, L. R.; Horner, J. E.

1987-11-01

119

Centrifuge (ChemPages Lab)  

NSDL National Science Digital Library

Centrifuge: this is a resource in the collection "ChemPages Laboratory Resources". The centrifuge is used to separate a solid from a solution quickly. A centrifuge is used for small-scale separations; typically the volume is less than 5 mL. Larger volumes of mixtures can be separated by filtration. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.

120

Study of a Supersonic Vortex Centrifuge  

NASA Astrophysics Data System (ADS)

A new device, called a supersonic vortex centrifuge (SVC), is used for separating one, or more, condensed phase constituents from a gas. The SVC consists of three components. In the order in which the gas mixture encounters these components, we have: (1) a curved sonic line minimum length nozzle (MLN) followed by (2) a vortex flow centrifuge, and finally (3) a diffuser. Throughout the nozzle, the flow is steady, two-dimensional, and shock free, except for a weak condensation shock wave. The shape of the nozzle and the flowfield properties are explicitly formulated, and a parametric analysis is presented. The trajectory of a particle is then determined in the vortex flow. It is assumed that the particles do not interact or perturb the gas flow. The particle motion depends on a pressure force, lift force, viscous drag force, and an apparent mass force. Rarefied effects on the motion of a particle are also included. A method-of-characteristics solution results in a system of ordinary differential equations that are integrated numerically. It is shown that the pressure, lift, and apparent mass forces are negligible in comparison with the viscous drag force. The primary parameters that effect the trajectory are the inner radius of the vortex flow and the mass of the particle.

Hourng, Lih-Wu Edmond

121

Flow in a tapered centrifuge  

SciTech Connect

Flow in a relatively short, tapered centrifuge is examined. The problem is formulated, various boundary layer regimes are analyzed, and the principal mass fluxes are calculated for general temperature and wall conditions. 3 references, 2 figures.

Greenspan, H.P.

1984-03-01

122

Microwave assisted centrifuge and related methods  

Microsoft Academic Search

Centrifuge samples may be exposed to microwave energy to heat the samples during centrifugation and to promote separation of the different components or constituents of the samples using a centrifuge device configured for generating microwave energy and directing the microwave energy at a sample located in the centrifuge.

Meikrantz; David H

2010-01-01

123

Microwave assisted centrifuge and related methods  

DOEpatents

Centrifuge samples may be exposed to microwave energy to heat the samples during centrifugation and to promote separation of the different components or constituents of the samples using a centrifuge device configured for generating microwave energy and directing the microwave energy at a sample located in the centrifuge.

Meikrantz, David H. (Idaho Falls, ID) [Idaho Falls, ID

2010-08-17

124

Centrifugal dryers keep pace with the market  

SciTech Connect

New plant design and upgrades create a shift in dewatering strategies. The article describes recent developments. Three major manufacturers supply centrifugal dryers - TEMA, Centrifugal & Mechanical Industries (CMI) and Ludowici. CMI introduced a line of vertical centrifugal dryers. TEMA improved the techniques by developing a horizontal vibratory centrifuge (HVC) which simplified maintenance. 3 figs., 1 photo.

Fiscor, S.

2008-03-15

125

Variable-Speed Instrumented Centrifuges  

NASA Technical Reports Server (NTRS)

Report describes conceptual pair of centrifuges, speed of which varied to produce range of artificial gravities in zero-gravity environment. Image and data recording and controlled temperature and gravity provided for 12 experiments. Microprocessor-controlled centrifuges include video cameras to record stop-motion images of experiments. Potential applications include studies of effect of gravity on growth and on production of hormones in corn seedlings, experiments with magnetic flotation to separate cells, and electrophoresis to separate large fragments of deoxyribonucleic acid.

Chapman, David K.; Brown, Allan H.

1991-01-01

126

Centrifugation during the Manhattan Project  

Microsoft Academic Search

Manhattan Engineer District documents from 1942 to early 1944 reveal that consideration of centrifugation as a means of enriching\\u000a uranium-235 during World War II was more extensive than is commonly appreciated. A full-scale prototype centrifuge was fabricated\\u000a and tested at near-production speeds; enrichments at close to levels expected theoretically was demonstrated with pilot-plant\\u000a units; and plans for production plants were

B. Cameron Reed

2009-01-01

127

Coral reef formation theory may apply to oil, gas exploration  

SciTech Connect

This paper reports a coral reef formation theory that has implications for hydrocarbon exploration. The theory states that many coral reefs and carbonate buildups from at and are dependent upon nutrient rich fluids seeping through the seabed.

Not Available

1990-12-10

128

Centrifugation. Sludge Treatment and Disposal Course #166. Instructor's Guide [and] Student Workbook.  

ERIC Educational Resources Information Center

An introductory description of the use of centrifuges in the process of volume reduction is provided in this lesson. Three basic centrifuges, their theory of operation, quality of cake and centrate, and operational control testing are discussed. The lesson includes an instructor's guide and student workbook. The instructor's guide contains a…

Best, Richard A.

129

TORSIONAL VIBRATION REDUCTION IN INTERNAL COMBUSTION ENGINES USING CENTRIFUGAL PENDULUMS  

Microsoft Academic Search

The goal of the present work is to investigate the performance of tautochronic centrifugal pendulum vibration absorbers (CPVA's) for reducing torsional vibration in internal combustion engines. A mathematical model is first built for the torsional dynamics of an in- line, four-stroke, four-cylinder engine, including the consideration of inertia effects of connecting rods and pistons, gas pressure inside the cylinder chambers,

Cheng-Tang Lee; Steven W. Shaw

130

Bubble Eliminator Based on Centrifugal Flow  

NASA Technical Reports Server (NTRS)

The fluid bubble eliminator (FBE) is a device that removes gas bubbles from a flowing liquid. The FBE contains no moving parts and does not require any power input beyond that needed to pump the liquid. In the FBE, the buoyant force for separating the gas from the liquid is provided by a radial pressure gradient associated with a centrifugal flow of the liquid and any entrained bubbles. A device based on a similar principle is described in Centrifugal Adsorption Cartridge System (MSC- 22863), which appears on page 48 of this issue. The FBE was originally intended for use in filtering bubbles out of a liquid flowing relatively slowly in a bioreactor system in microgravity. Versions that operate in normal Earth gravitation at greater flow speeds may also be feasible. The FBE (see figure) is constructed as a cartridge that includes two concentric cylinders with flanges at the ends. The outer cylinder is an impermeable housing; the inner cylinder comprises a gas-permeable, liquid-impermeable membrane covering a perforated inner tube. Multiple spiral disks that collectively constitute a spiral ramp are mounted in the space between the inner and outer cylinders. The liquid enters the FBE through an end flange, flows in the annular space between the cylinders, and leaves through the opposite end flange. The spiral disks channel the liquid into a spiral flow, the circumferential component of which gives rise to the desired centrifugal effect. The resulting radial pressure gradient forces the bubbles radially inward; that is, toward the inner cylinder. At the inner cylinder, the gas-permeable, liquid-impermeable membrane allows the bubbles to enter the perforated inner tube while keeping the liquid in the space between the inner and outer cylinders. The gas thus collected can be vented via an endflange connection to the inner tube. The centripetal acceleration (and thus the radial pressure gradient) is approximately proportional to the square of the flow speed and approximately inversely proportional to an effective radius of the annular space. For a given FBE geometry, one could increase the maximum rate at which gas could be removed by increasing the rate of flow to obtain more centripetal acceleration. In experiments and calculations oriented toward the original microgravitational application, centripetal accelerations between 0.001 and 0.012 g [where g normal Earth gravitation (.9.8 m/s2)] were considered. For operation in normal Earth gravitation, it would likely be necessary to choose the FBE geometry and the rate of flow to obtain centripetal acceleration comparable to or greater than g.

Gonda, Steve R.; Tsao, Yow-Min D.; Lee, Wenshan

2004-01-01

131

Galactic evolution. I - Single-zone models. [encompassing stellar evolution and gas-star dynamic theories  

NASA Technical Reports Server (NTRS)

The two basic approaches of physical theory required to calculate the evolution of a galactic system are considered, taking into account stellar evolution theory and the dynamics of a gas-star system. Attention is given to intrinsic (stellar) physics, extrinsic (dynamical) physics, and computations concerning the fractionation of an initial mass of gas into stars. The characteristics of a 'standard' model and its variants are discussed along with the results obtained with the aid of these models.

Thuan, T. X.; Hart, M. H.; Ostriker, J. P.

1975-01-01

132

Continuum approach to phonon gas and shape changes of second sound via shock waves theory  

Microsoft Academic Search

Summary  A continuum approach, based on the principles of modern extended thermodynamics, describing the model of a phonon gas is performed.\\u000a The main difference with the ideal phonon gas theory consists in the presence of athermal inertia. We apply the shock wave theory and discuss the selection rules for physical shocks (theLax conditions and theentropy growth). In this way the existence

T. Ruggeri; A. Muracchini; L. Seccia

1994-01-01

133

On the characteristics of centrifugal-reciprocating machines. [cryogenic coolers  

NASA Technical Reports Server (NTRS)

A method of compressing helium gas for cryogenic coolers is presented which uses centrifugal force to reduce the forces on the connecting rod and crankshaft in the usual reciprocating compressor. This is achieved by rotating the piston-cylinder assembly at a speed sufficient for the centrifugal force on the piston to overcome the compressional force due to the working fluid. The rotating assembly is dynamically braked in order to recharge the working space with fluid. The intake stroke consists of decelerating the rotating piston-cylinder assembly and the exhaust stroke consists of accelerating the assembly.

Higa, W. H.

1980-01-01

134

40 CFR 60.5380 - What standards apply to centrifugal compressor affected facilities?  

...CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Crude Oil and Natural Gas Production, Transmission and Distribution § 60.5380 What standards apply to centrifugal...

2014-07-01

135

40 CFR 60.5380 - What standards apply to centrifugal compressor affected facilities?  

Code of Federal Regulations, 2013 CFR

...CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Crude Oil and Natural Gas Production, Transmission and Distribution § 60.5380 What standards apply to centrifugal...

2013-07-01

136

Physiologia Plantarum 140: 311320. 2010 Copyright Physiologia Plantarum 2010, ISSN 0031-9317 What happens when stems are embolized in a centrifuge?  

E-print Network

-9317 What happens when stems are embolized in a centrifuge? Testing the cavitron theory Jing Caia,b, Uwe of stems. The fastest method of measuring VCs is the centrifuge technique and the Cochard cavitron in a centrifuge ought to differ from the pattern during natural dehydration of plants because the profiles

Hacke, Uwe

137

Plasma centrifuge development at INPE  

NASA Astrophysics Data System (ADS)

The plasma centrifuge is a device in which a fully ionized plasma column rotates at high angular velocities by means of crossed electric and magnetic fields. Ion angular rotation frequencies of 6.9 x 10,000 to 1.2 x 100,000 rad/s were measured for a carbon plasma, with an externally applied magnetic field of 0.09T. Isotopic enrichments of up to 390 percent for C-13 were measured at 6 cm radius. The steady state behavior of the fully ionized magnetized plasma in the vacuum arc centrifuge was theoretically investigated using a multiple species fluid model, which includes electromagnetic, pressure gradient, centrifugal and collisional forces in cylindrical geometry.

Bittencourt, J. A.; Delbosco, E.; Dallaqua, R. S.; Ludwig, G. O.

1987-07-01

138

Centrifugation and the Manhattan Project  

NASA Astrophysics Data System (ADS)

A study of U. S. Army Manhattan Engineer District documents reveals that consideration of centrifugation as a means of uranium enrichment during World War II was considerably more extensive than is commonly appreciated. By the time the centrifuge project was abandoned in early 1944 a full-scale prototype unit had been fabricated and tested at near-production speeds, enrichments of close to theoretically-expected levels had been demonstrated with pilot-plant units, and plans for production plants had been developed. This paper will review the history of this little-known aspect of the Project and examine the circumstances of how it came to be discontinued.

Reed, Cameron

2009-04-01

139

Centrifugation and the Manhattan Project  

NASA Astrophysics Data System (ADS)

A study of U. S. Army Manhattan Engineer District documents reveals that consideration of centrifugation as a means of uranium enrichment during World War II was considerably more extensive than is commonly appreciated. By the time the centrifuge project was abandoned in early 1944 a full-scale prototype unit had been fabricated and tested at near-production speeds, enrichments of close to theoretically-expected levels had been demonstrated with pilot-plant units, and plans for production plants had been developed. This paper will review the history of this little-known aspect of the Project and examine the circumstances of how it came to be discontinued.

Reed, Cameron

2009-05-01

140

Membrane-Based Characterization of a Gas Component — A Transient Sensor Theory  

PubMed Central

Based on a multi-gas solution-diffusion problem for a dense symmetrical membrane this paper presents a transient theory of a planar, membrane-based sensor cell for measuring gas from both initial conditions: dynamic and thermodynamic equilibrium. Using this theory, the ranges for which previously developed, simpler approaches are valid will be discussed; these approaches are of vital interest for membrane-based gas sensor applications. Finally, a new theoretical approach is introduced to identify varying gas components by arranging sensor cell pairs resulting in a concentration independent gas-specific critical time. Literature data for the N2, O2, Ar, CH4, CO2, H2 and C4H10 diffusion coefficients and solubilities for a polydimethylsiloxane membrane were used to simulate gas specific sensor responses. The results demonstrate the influence of (i) the operational mode; (ii) sensor geometry and (iii) gas matrices (air, Ar) on that critical time. Based on the developed theory the case-specific suitable membrane materials can be determined and both operation and design options for these sensors can be optimized for individual applications. The results of mixing experiments for different gases (O2, CO2) in a gas matrix of air confirmed the theoretical predictions. PMID:24608004

Lazik, Detlef

2014-01-01

141

HYDROCLONES AND LIQUID CENTRIFUGES. A Literature Search  

Microsoft Academic Search

A literature search for information concerning centrifugal devices was ; conducted. A listing containing 47 references to unclassified report literature ; dealing with hydroclones and centrifuges is presented. Availability is given for ; all reports. (J.R.D.);

J. M. comp

1959-01-01

142

Life Sciences Centrifuge Facility assessment  

NASA Technical Reports Server (NTRS)

This report provides an assessment of the status of the Centrifuge Facility being developed by ARC for flight on the International Space Station Alpha. The assessment includes technical status, schedules, budgets, project management, performance of facility relative to science requirements, and identifies risks and issues that need to be considered in future development activities.

Benson, Robert H.

1994-01-01

143

Centrifugal separation of a mixture  

Microsoft Academic Search

In this review, we shall present a survey about recent developments in the understanding of the separation of a mixture in a rotating vessel. Based on the first principles of fluid dynamics and earlier substantial results concerned with gravity settling, recently a great variety of investigations has been published for different centrifugal devices and ranges of parameters. We shall summarize

Uwe Schaflinger

1990-01-01

144

ORNL centrifuge pellet fueling system  

Microsoft Academic Search

A centrifuge pellet injecter designed and built at Oak Ridge National Laboratory (ORNL) is in operation on Tore Supra. This injector has the capability of injecting up to 100 pellets at speeds up to 800 M\\/s. The solid deuterium pellets can be formed with a variable mass from 3 to 10 torr-L and are fired at a rate of up

C. A. Foster; W. A. Houlberg; M. J. Gouge; M. J. Grapperhaus; S. L. Milora; H. Drawin; A. Geraud; M. Chatelier; G. Gros

1992-01-01

145

Life Sciences Centrifuge Facility review  

NASA Technical Reports Server (NTRS)

The Centrifuge Facility Project at ARC was reviewed by a code U team to determine appropriateness adequacy for the ISSA. This report represents the findings of one consultant to this team and concentrates on scientific and technical risks. This report supports continuation of the project to the next phase of development.

Young, Laurence R.

1994-01-01

146

Centrifugal pumps for rocket engines  

NASA Technical Reports Server (NTRS)

The use of centrifugal pumps for rocket engines is described in terms of general requirements of operational and planned systems. Hydrodynamic and mechanical design considerations and techniques and test procedures are summarized. Some of the pump development experiences, in terms of both problems and solutions, are highlighted.

Campbell, W. E.; Farquhar, J.

1974-01-01

147

Correlation of cavitating centrifugal pumps  

Microsoft Academic Search

The foreknowledge of the minimum NPSH ('net positive suction head') required for a cavitation-free performance of centrifugal pumps is important for a safe and sound operation of these machines. The required NPSH varies from pump to pump, from fluid to fluid, and from temperature to temperature of the pumped fluid. This is known as the thermodynamic effect. The methods currently

V. J. Zika

1984-01-01

148

Density functional theory and free energy of inhomogeneous electron gas  

Microsoft Academic Search

It is shown that in adiabatic approximation for nuclei the many-component Coulomb system cannot be described on the basis of the grand canonical ensemble. Using the variational Bogolyubov's procedure for the free energy, the Hohenberg-Kohn theorem is proved in the canonical ensemble for inhomogeneous electron gas at finite temperature. The principal difference between consideration in the framework of quantum statistics

V. B. Bobrov; S. A. Trigger

2010-01-01

149

Centrifugal microdevices Chip-based analysis systems provide for  

E-print Network

Centrifugal microdevices Chip-based analysis systems provide for efficiency gains with respect the potential applications of such instruments. Centrifugation is a well- established sample pre or macromolecules of differing sizes in suspension. Macroscale centrifuges typically generate high centrifugal

Rogers, John A.

150

Centrifugal Filter Devices FOR CONCENTRATION AND PURIFICATION  

E-print Network

Centricon® Plus-70 Centrifugal Filter Devices FOR CONCENTRATION AND PURIFICATION OF BIOLOGICAL-70 centrifugal filter is a disposable, single-use device designed for rapid processing of aqueous biological solu- tions in volumes ranging from 15 to 70 mL. It is compatible with swinging-bucket centrifuges

Kirschner, Marc W.

151

Shape separation of gold nanorods using centrifugation  

E-print Network

Shape separation of gold nanorods using centrifugation Vivek Sharmaa,1 , Kyoungweon Parka,2, and approved January 23, 2009 (received for review January 29, 2008) We demonstrate the use of centrifugation particles to have shape-dependent sedimentation behavior. During centrifugation, nanoparticles undergo

Srinivasarao, Mohan

152

Centrifugal separator devices, systems and related methods  

Microsoft Academic Search

Centrifugal separator devices, systems and related methods are described. More particularly, fluid transfer connections for a centrifugal separator system having support assemblies with a movable member coupled to a connection tube and coupled to a fixed member, such that the movable member is constrained to movement along a fixed path relative to the fixed member are described. Also, centrifugal separator

David H. Meikrantz; Jack D. Law; Troy G. Garn; Terry A. Todd; Lawrence L. Macaluso

2012-01-01

153

Centrifugal tube mill for finest grinding  

Microsoft Academic Search

The design and the motion behaviour of the filling of a new centrifugal tube mill are introduced. In contrast to the usual range of application for centrifugal tube mills, once developed to substitute ball mills, it is shown that centrifugal tube mills are particularly suited for pulverizing if the grinding media filling is reduced to max. 35%. This measure also

K.-E. Kurrer; E. Gock; V. Vogt; R. Florescu

2004-01-01

154

Density functional theory and free energy of inhomogeneous electron gas  

Microsoft Academic Search

It is shown that in adiabatic approximation for nuclei the many-component\\u000aCoulomb system cannot be described on the basis of the grand canonical\\u000aensemble. Using the variational Bogolyubov's procedure for the free energy, the\\u000aHohenberg-Kohn theorem is proved in the canonical ensemble for inhomogeneous\\u000aelectron gas at finite temperature. The principal difference between\\u000aconsideration in the framework of quantum statistics

V. B. Bobrov; S. A. Trigger

2010-01-01

155

Lattice gas hydrodynamics: Theory and simulations. Final report  

SciTech Connect

The first successful application of a microscopic analogy to create a skeleton cellular automaton and analyze it with statistical mechanical tools, was the work of Frisch, Hasslacher and Pomeau on the Navier-Stokes equation in two and three dimensions. This has become a very large research area with lattice gas models and methods being used for both fundamental investigations into the foundations of statistical mechanics and a large number of diverse applications. This present research was devoted to enlarging the fundamental scope of lattice gas models and proved quite successful. Since the beginning of this proposal, cellular automata have been constructed for statistical mechanical models, fluids, diffusion and shock systems in fundamental investigations. In applied areas, there are now excellent lattice gas models for complex flows through porous media, chemical reaction and combustion dynamics, multiphase flow systems, and fluid mixtures with natural boundaries. With extended cellular fluid models, one can do problems with arbitrary pairwise potentials. Recently, these have been applied to such problems as non-newtonian or polymeric liquids and a mixture of immiscible fluids passing through fractal or spongelike media in two and three dimensions. This proposal has contributed to and enlarged the scope of this work.

Hasslacher, B.

1993-05-01

156

Impact of Airway Gas Exchange on the Multiple Inert Gas Elimination Technique: Theory  

PubMed Central

The multiple inert gas elimination technique (MIGET) provides a method for estimating alveolar gas exchange efficiency. Six soluble inert gases are infused into a peripheral vein. Measurements of these gases in breath, arterial blood, and venous blood are interpreted using a mathematical model of alveolar gas exchange (MIGET model) that neglects airway gas exchange. A mathematical model describing airway and alveolar gas exchange predicts that two of these gases, ether and acetone, exchange primarily within the airways. To determine the effect of airway gas exchange on the MIGET, we selected two additional gases, toluene and m-dichlorobenzene, that have the same blood solubility as ether and acetone and minimize airway gas exchange via their low water solubility. The airway-alveolar gas exchange model simulated the exchange of toluene, m-dichlorobenzene, and the six MIGET gases under multiple conditions of alveolar ventilation-to-perfusion, V?A/Q?, heterogeneity. We increased the importance of airway gas exchange by changing bronchial blood flow, Q?br. From these simulations, we calculated the excretion and retention of the eight inert gases and divided the results into two groups: 1) the standard MIGET gases which included acetone and ether and 2) the modified MIGET gases which included toluene and m-dichlorobenzene. The MIGET mathematical model predicted distributions of ventilation and perfusion for each grouping of gases and multiple perturbations of V?A/Q? and Q?br. Using the modified MIGET gases, MIGET predicted a smaller dead space fraction, greater mean V?A, greater log(SDVA), and more closely matched the imposed V?A distribution than that using the standard MIGET gases. Perfusion distributions were relatively unaffected. PMID:20336837

Anderson, Joseph C.; Hlastala, Michael P.

2011-01-01

157

Centrifugal separator devices, systems and related methods  

DOEpatents

Centrifugal separator devices, systems and related methods are described. More particularly, fluid transfer connections for a centrifugal separator system having support assemblies with a movable member coupled to a connection tube and coupled to a fixed member, such that the movable member is constrained to movement along a fixed path relative to the fixed member are described. Also, centrifugal separator systems including such fluid transfer connections are described. Additionally, methods of installing, removing and/or replacing centrifugal separators from centrifugal separator systems are described.

Meikrantz, David H. (Idaho Falls, ID); Law, Jack D. (Pocatello, ID); Garn, Troy G. (Idaho Falls, ID); Todd, Terry A. (Aberdeen, ID); Macaluso, Lawrence L. (Carson City, NV)

2012-03-20

158

Application of Watson's centrifugal distortion theory to water and light asymmetric tops. General methods. Analysis of the ground state and the nu2 state of D2O16  

Microsoft Academic Search

Watson's reduced Hamiltonian proved adapted for treating the rotation of light molecules which show very large effects of centrifugal distortion. In order to determine which terms are required and which are negligible (choice of an effective model), we have studied the order of magnitude of the terms from a theoretical point of view. This order depends on the coefficient and

Guy Steenbeckeliers; Jean Bellet

1973-01-01

159

Density functional theory and free energy of inhomogeneous electron gas  

E-print Network

It is shown that in adiabatic approximation for nuclei the many-component Coulomb system cannot be described on the basis of the grand canonical ensemble. Using the variational Bogolyubov's procedure for the free energy, the Hohenberg-Kohn theorem is proved in the canonical ensemble for inhomogeneous electron gas at finite temperature. The principal difference between consideration in the framework of quantum statistics in the canonical ensemble and quantum-mechanical consideration of a finite number of particles in infinite volume is established. The problem of universality of the density functional for describing the inhomogeneous electron density in a disordered nuclei field is considered.

Bobrov, V B

2010-01-01

160

Density functional theory and free energy of inhomogeneous electron gas  

E-print Network

It is shown that in adiabatic approximation for nuclei the many-component Coulomb system cannot be described on the basis of the grand canonical ensemble. Using the variational Bogolyubov's procedure for the free energy, the Hohenberg-Kohn theorem is proved in the canonical ensemble for inhomogeneous electron gas at finite temperature. The principal difference between consideration in the framework of quantum statistics in the canonical ensemble and quantum-mechanical consideration of a finite number of particles in infinite volume is established. The problem of universality of the density functional for describing the inhomogeneous electron density in a disordered nuclei field is considered.

V. B. Bobrov; S. A. Trigger

2010-04-06

161

Centrifugal separation of a mixture  

NASA Astrophysics Data System (ADS)

In this review, we shall present a survey about recent developments in the understanding of the separation of a mixture in a rotating vessel. Based on the first principles of fluid dynamics and earlier substantial results concerned with gravity settling, recently a great variety of investigations has been published for different centrifugal devices and ranges of parameters. We shall summarize the results and provide a general view about their validity and practical applications. Finally, we shall outline possibilities for further theoretical and experimental research that is stimulated by new phenomena. Even though the theoretical results are restricted to monodisperse, Newtonian suspensions, consisting of small spherical particles freely suspended in a clear fluid, and bulk settling, the results and the physical insight gained can be applied to many industrial problems like continuous separation and filtration in centrifuges.

Schaflinger, Uwe

1990-12-01

162

Unstable flow in centrifugal fans  

SciTech Connect

Rotating stall and the inlet vortex in centrifugal fans with inlet vane control has been studied. The advances in stall research in aero-engine compressors are discussed. The present study shows that stall in centrifugal fans can be quite different from that in axial compressors, in that stall can occur in a progressive and intermittent fashion. The study also shows that a discontinuity in the fan characteristic is not necessarily accompanied by rotating stall, unlike the axial machines. Experimental results indicate that the positive prewhirl created by inlet vanes tends to delay the occurrence of stall. Also, dorsal fin devices that are used to control the inlet vortex do not seem to affect the stall point unfavorably. The inlet vortex frequency was found to invariably exhibit a linear relation with the flow rate even when dorsal fins were used. This offers a practical method to distinguish between the inlet vortex and rotating stall.

Chen, P. [Nanyang Technological Univ., Singapore (Singapore). School of Mechanical and Production Engineering; Soundra-Nayagam, M. [Loughborough Univ. of Technology (United Kingdom). Dept. of Electrical and Electronics Engineering; Bolton, A.N. [National Engineering Lab., Glasgow (United Kingdom). Flow Center; Simpson, H.C. [Univ. of Strathclyde, Glasgow (United Kingdom). Dept. of Mechanical and Processing Engineering

1996-03-01

163

The Lifshitz-Kosevich-Shoenberg theory of relativistic electronic gas in neutron stars  

NASA Astrophysics Data System (ADS)

Similar to the de Haas-van Alphen magnetic oscillatory in some normal metals when the Landau quantization is predominant, the magnetic oscillation can also occur in highly degenerate and relativistic electron gas in neutron stars. At large Landau quantum number (Landau quantum number r?2), we generalize the Lifshitz-Kosevich-Shoenberg theory in non-relativistic electron gas to relativistic gas. At small Landau quantum number ( r<2), we expand the grand potential into Fourier series and get similar harmonic oscillatory formula of magnetization. These results indicate that magnetic phase transition similar as Condon transition observed in metals can appear in neutron stars when the differential susceptibility exceeds 1/4 ?.

Wang, Zhaojun; Lü, Guoliang; Zhu, Chunhua

2014-10-01

164

Parents of two-phase flow and theory of "gas-lift"  

NASA Astrophysics Data System (ADS)

This paper gives a brief overview of types of two-phase flow. Subsequently, it deals with their mutual division and problems with accuracy boundaries among particular types. It also shows the case of water flow through a pipe with external heating and the gradual origination of all kinds of flow. We have met it in solution of safety condition of various stages in pressurized and boiling water reactors. In the MSR there is a problem in the solution of gas-lift using helium as a gas and its secondary usage for clearing of the fuel mixture from gaseous fission products. Theory of gas-lift is described.

Zitek, Pavel; Valenta, Vaclav

2014-03-01

165

Centrifugal impact milling of resins  

Microsoft Academic Search

Investigation of phenol formaldehyde resins milling in centrifugal impact mills is presented. The particle size distribution,\\u000a energy consumption and size reduction ratio were observed at different material loads, grinding rotor velocities and air flow\\u000a rates. Experimentally measured data were modelled using previously developed Rosin–Rammler formula and two parameters; the\\u000a mean particle size and the width of distribution were calculated for

Iztok Hace

2010-01-01

166

Modelling and simulation of heavy gas dispersion on the basis of modifications in plume path theory.  

PubMed

An analytical model for heavy gas dispersion based on the modifications in plume path theory has been developed. The model takes into account the variations in temperature, density, and specific heat during the movement of heavy gas plume. The model has been tested for three hazardous gases - chlorine, natural gas and liquefied petroleum gas. The results have been compared with the recently generated experimental data as also with the outputs of other models. A good agreement is observed qualitatively as well as quantitatively. A study has also been carried out to simulate the effect of the wind speed, density of the gas, and venting speed on dispersion. Based on the simulation study a set of empirical equations has been developed. The equations are validated by theoretical as well as experimental studies. PMID:11080566

Khan, F I; Abbasi, S A

2000-12-30

167

Electron gas oscillations in plasma. Theory and applications  

E-print Network

We analyze the obtained solutions of the non-linear Shr{"o}dinger equation for spherically and axially symmetrical electrons density oscillations in plasma. The conditions of the oscillations process existence are examined. It is shown that in the center or on the axis of symmetry of the systems the static density of electrons enhances. This process results in the increasing of density and pressure of the ion gas. We suggest that this mechanism could occur in nature as rare phenomenon called the 'fireball' and could be used in carrying out the research concerning controlled fusion. The description of the experiments, carried out for the purpose to generate long-lived spherical plasma structures, is presented.

Dvornikov, M S; Dvornikov, Maxim; Dvornikov, Sergey

2003-01-01

168

Using the centrifugal method for the plasma-arc vitrification of waste  

NASA Astrophysics Data System (ADS)

Plasma-arc centrifugal treatment vitrification technology has advanced from the first experiments in 1985 to occupy a niche in the waste-treatment market. The centrifugal action, the force of the plasma gas, and the water-cooled walls work together to generate a durable, homogenous, vitrified waste form coupled with the safe confinement of th e hazardous feeds and high organic removal efficiency. This technology has recently been applied to treat wastes completely while achieving maximum volume reduction.

Womack, R. K.

1999-10-01

169

Post-evaluation of Power Plant Flue Gas Desulfurization Project Based on Theory of Value Management  

Microsoft Academic Search

With the rapid development of the Thermal Power Plant Flue Gas Desulfurization (FGD) industry, Desulfurization Project has a wide developing prospect in the present market. However, the levels of Desulfurization enterprises mix and owners are unfamiliar with the desulfurization project, which increase the investment and cannot reach the expected desulfurization effect. Applying the theory of value management in post-evaluation of

Yun-na Wu; Ying-ying Huang; Zhi-jun Huang

2009-01-01

170

Quasilinear theory of collisionless electron heating in radio frequency gas discharges  

E-print Network

parameters. Due to the large value of the mean free path MFP the main mechanism of electron heating turns outQuasilinear theory of collisionless electron heating in radio frequency gas discharges Yu. M. Aliev heating of rf discharges is treated for characteristic scale lengths of the heating field much shorter

Kaganovich, Igor

171

Twinning of amphibian embryos by centrifugation  

NASA Technical Reports Server (NTRS)

In the frog Xenopus laevis, the dorsal structures of the embryonic body axis normally derive from the side of the egg opposite the side of sperm entry. However, if the uncleaved egg is inclined at lg or centrifuged in an inclined position, this topographic relationship is overridden: the egg makes its dorsal axial structures according to its orientation in the gravitational/centrifugal field, irrespective of the position of sperm entry. Certain conditions of centrifugation cause eggs to develop into conjoined twins with two sets of axial structures. A detailed analysis of twinning provided some insight into experimental axis orientation. First, as with single-axis embryos, both axes in twins are oriented according to the direction of centrifugation. One axis forms at the centripetal side of the egg and the other forms at the centrifugal side, even when the side of sperm entry is normal to the centrifugal force vector. Second, if eggs are centrifuged to give twins, but are inclined at lg to prevent post-centrifugation endoplasmic redistributions, only single-axis embryos develop. Thus, a second redistribution is required for high-frequency secondary axis formation. This can be accomplished by lg (as in the single centrifugations) or by a second centrifugation directed along the egg's animal-vegetal axis.

Black, S. D.

1984-01-01

172

Biot-Gassmann theory for velocities of gas hydrate-bearing sediments  

USGS Publications Warehouse

Elevated elastic velocities are a distinct physical property of gas hydrate-bearing sediments. A number of velocity models and equations (e.g., pore-filling model, cementation model, effective medium theories, weighted equations, and time-average equations) have been used to describe this effect. In particular, the weighted equation and effective medium theory predict reasonably well the elastic properties of unconsolidated gas hydrate-bearing sediments. A weakness of the weighted equation is its use of the empirical relationship of the time-average equation as one element of the equation. One drawback of the effective medium theory is its prediction of unreasonably higher shear-wave velocity at high porosities, so that the predicted velocity ratio does not agree well with the observed velocity ratio. To overcome these weaknesses, a method is proposed, based on Biot-Gassmann theories and assuming the formation velocity ratio (shear to compressional velocity) of an unconsolidated sediment is related to the velocity ratio of the matrix material of the formation and its porosity. Using the Biot coefficient calculated from either the weighted equation or from the effective medium theory, the proposed method accurately predicts the elastic properties of unconsolidated sediments with or without gas hydrate concentration. This method was applied to the observed velocities at the Mallik 2L-39 well, Mackenzie Delta, Canada.

Lee, M.W.

2002-01-01

173

Mass transfer between a multicomponent trapped gas phase and a mobile water phase: Experiment and theory  

NASA Astrophysics Data System (ADS)

Gas tracer experiments were carried out in dynamically compressed sediments to investigate the mass transfer between a trapped multicomponent gas phase and a mobile water phase. The saturation state of the column was characterized by three independent methods: (1) by gravimetric measurements, (2) by bromide tracer tests, and (3) by hydraulic conductivity measurements. For inverse modeling a new kinetic model was developed allowing volume change of the entrapped gas. The new kinetic model consistently explains oxygen elution curves, the time evolution of the integral gas saturation, and integral hydraulic conductivity. The sensitivity of three different velocity-dependent mass transfer correlations to the dissolution process was investigated: (1) a classical square-root, single-sphere correlation, Sh ˜ Pe0.5, (2) a multisphere correlation, Sh ˜ Pen (n = 0.5-1.0), and (3) an empirical correlation, Sh ˜ Pe0.8. It was found that all correlations yield nearly the same elution curves for 10 gas tracer experiments with three different two-component gas phases: O2/He, O2/N2, and O2/Ar and for different flow velocities ranging from 5 to 20 m d-1. For all gas tracer experiments a distinct minimum of the longitudinal dispersivity was found during gas dissolution, i.e., in the unsaturated state. For the saturated state we found that the experimental values could be described by Saffman's theory: ?p ? Pe ln (Pe) with a normalized mean square root error of 6%.

Geistlinger, Helmut; Beckmann, Annika; Lazik, Detlef

2005-11-01

174

Comparison between theory and experiment for universal thermodynamics of a homogeneous, strongly correlated Fermi gas  

SciTech Connect

We compare the theoretical predictions for universal thermodynamics of a homogeneous, strongly correlated Fermi gas with the latest experimental measurements reported by the ENS group [S. Nascimbene et al., Nature (London) 463, 1057 (2010)] and the Tokyo group [M. Horikoshi et al., Science 327, 442 (2010)]. The theoretical results are obtained using two diagrammatic theories, together with a virial expansion theory combined with a Pade approximation. We find good agreement between theory and experiment. In particular, the virial expansion, using a Pade approximation up to third order, describes the experimental results extremely well down to the superfluid transition temperature, T{sub c{approx}}0.16T{sub F}, where T{sub F} is the Fermi temperature. The comparison in this work complements our previous comparative study on the universal thermodynamics of a strongly correlated but trapped Fermi gas. The comparison also raises interesting issues about the unitary entropy and the applicability of the Pade approximation.

Hu Hui; Liu Xiaji; Drummond, Peter D. [ARC Centre of Excellence for Quantum-Atom Optics, Centre for Atom Optics and Ultrafast Spectroscopy, Swinburne University of Technology, Melbourne 3122, Victoria (Australia)

2011-06-15

175

Structure and dynamics of noble gas-halogen and noble gas ionic clusters: When theory meets experiment  

NASA Astrophysics Data System (ADS)

As part of this special issue in honor of Gerardo Delgado Barrio, we have reviewed the interplay between experimental and theoretical work on halogen and interhalogen diatomic molecule bonded to one or more noble gas atoms and also ionic clusters consisting of noble gas atoms. Although the Madrid group has worked on many theoretical issues, they have made particularly important contributions to these two topics. Delgado Barrio has often chosen topics for study for which close interactions between theorists and experimentalists are especially useful. During the historical span of the group, we have progressed from approximate models whose goal was to capture the essence of a process even if the details were impossible to reproduce, to an era in which theory is an equal partner with experiment, and, in fact, often provides a detailed understanding beyond that obtained from a careful analysis of state-of-the-art data.

Beswick, J. A.; Halberstadt, N.; Janda, K. C.

2012-05-01

176

Pneumatic flow switching on centrifugal microfluidic platforms in motion.  

PubMed

This paper describes a flow switching technique applicable to centrifugal microfluidic platforms, using a regulated stream of compressed gas. This pneumatic flow switching technique allows for flow control at a T-shaped junction between one inlet channel and two outlet channels. This technique provides a noncontact, robust, and efficient method for switching the direction of fluid flow while a disk is rotating at relatively low frequencies. The switching operation can be implemented reproducibly with applied gas flow rates between 17 and 58 L min(-1) and rotational frequencies between 400 rpm (6.6 Hz) and 1200 rpm (20 Hz). PMID:21218773

Kong, Matthew C R; Salin, Eric D

2011-02-01

177

Centrifugal quantum states of neutrons  

E-print Network

We propose a method for observation of the quasi-stationary states of neutrons, localized near the curved mirror surface. The bounding effective well is formed by the centrifugal potential and the mirror Fermi-potential. This phenomenon is an example of an exactly solvable "quantum bouncer" problem that could be studied experimentally. It could provide a promising tool for studying fundamental neutron-matter interactions, as well as quantum neutron optics and surface physics effects. We develop formalism, which describes quantitatively the neutron motion near the mirror surface. The effects of mirror roughness are taken into account.

V. V. Nesvizhevsky; A. K. Petukhov; K. V. Protasov; A. Yu. Voronin

2008-06-24

178

An Attack on Centrifugal Costs  

E-print Network

the necessary audit of plant centrifugal systems. Primarily, the task force will review applications of 50 to 1500 HP. This paper will discuss some of the technology that has been used by this task force in several successful innovative conservation... Force was adopted.. After an organizational meeting, the task forcei began a series of audits on simple systems. T~~ task force targeted on systems of 250-1500 HP. I To date, cost effective savings opportunities hfve been found in every system...

Murray, P. F.

179

Centrifugal separators and related devices and methods  

DOEpatents

Centrifugal separators and related methods and devices are described. More particularly, centrifugal separators comprising a first fluid supply fitting configured to deliver fluid into a longitudinal fluid passage of a rotor shaft and a second fluid supply fitting sized and configured to sealingly couple with the first fluid supply fitting are described. Also, centrifugal separator systems comprising a manifold having a drain fitting and a cleaning fluid supply fitting are described, wherein the manifold is coupled to a movable member of a support assembly. Additionally, methods of cleaning centrifugal separators are described.

Meikrantz, David H. (Idaho Falls, ID); Law, Jack D. (Pocatello, ID); Garn, Troy G. (Idaho Falls, ID); Macaluso, Lawrence L. (Carson City, NV); Todd, Terry A. (Aberdeen, ID)

2012-03-06

180

The function of gas vesicles in halophilic archaea and bacteria: theories and experimental evidence.  

PubMed

A few extremely halophilic Archaea (Halobacterium salinarum, Haloquadratum walsbyi, Haloferax mediterranei, Halorubrum vacuolatum, Halogeometricum borinquense, Haloplanus spp.) possess gas vesicles that bestow buoyancy on the cells. Gas vesicles are also produced by the anaerobic endospore-forming halophilic Bacteria Sporohalobacter lortetii and Orenia sivashensis. We have extensive information on the properties of gas vesicles in Hbt. salinarum and Hfx. mediterranei and the regulation of their formation. Different functions were suggested for gas vesicle synthesis: buoying cells towards oxygen-rich surface layers in hypersaline water bodies to prevent oxygen limitation, reaching higher light intensities for the light-driven proton pump bacteriorhodopsin, positioning the cells optimally for light absorption, light shielding, reducing the cytoplasmic volume leading to a higher surface-area-to-volume ratio (for the Archaea) and dispersal of endospores (for the anaerobic spore-forming Bacteria). Except for Hqr. walsbyi which abounds in saltern crystallizer brines, gas-vacuolate halophiles are not among the dominant life forms in hypersaline environments. There only has been little research on gas vesicles in natural communities of halophilic microorganisms, and the few existing studies failed to provide clear evidence for their possible function. This paper summarizes the current status of the different theories why gas vesicles may provide a selective advantage to some halophilic microorganisms. PMID:25371329

Oren, Aharon

2012-01-01

181

Urenco centrifuge and laser development  

SciTech Connect

The Urenco centrifuge process for the enrichment of uranium is now well developed and economically proven. The centrifuge technology that forms the basis of Urenco`s plants in the United Kingdom, the Netherlands, and Germany has evolved steadily over the last two decades since the Urenco partnership was formed, and current programs of development will see this progress continue into the next century. From the early pilot plant work, the first generation of machines was installed and commissioned in the late 1970s in the U.K. and Netherlands plants. These have both significantly exceeded the original design expectation with respect to both stress lifetime and corrosion resistance. The early U.K. plant was shut down in 1992, again well beyond the expected 10-yr lifetime, while the Netherlands plant is still operating. Since then, significant advances have been made, and a fourth-generation machine began operation in the plants in 1991; in fact, Urenco has all four generations still in operation in its plants today. Urenco`s research on laser isotope separation is also described.

Upson, P.C.

1994-12-31

182

Exact-exchange density-functional theory applied to a strongly inhomogeneous electron gas  

Microsoft Academic Search

A recently developed quasi two-dimensional exact-exchange formalism within\\u000athe framework of Density Functional Theory has been applied to a strongly\\u000ainhomogeneous interacting electron gas, and the results were compared with\\u000astate-of-the-art Variational Quantum Monte Carlo (VMC) numerical simulations\\u000afor a three-dimensional electron gas under a strong external potential. The VMC\\u000aresults, extremely demanding from the computational point of view, could

S. Rigamonti; F. A. Reboredo; C. R. Proetto

2003-01-01

183

Induced velocities of grains embedded in a turbulent gas. [test particle theory application to protostellar clouds  

NASA Technical Reports Server (NTRS)

A theory is presented for the dynamics of dust particles in an incompressible turbulent fluid. Grain-gas coupling occurs through friction forces that are proportional to the mean grain velocity relative to the gas. This test particle theory is applied to the case of Kolmogoroff spectrum in a protostellar cloud. The mean turbulence induced grain velocity and the mean turbulent relative velocity of two grains are calculated. Whereas the former should determine the dust scale height, grain-grain collisions are influenced by the latter. For a reasonable strength of turbulence, the mean induced relative velocity of two particles turns out to be at least as large as the corresponding terminal velocity difference during gravitational settling.

Voelk, H. J.; Morfill, G.; Roeser, S.; Jones, F. C.

1978-01-01

184

Centrifugally driven diffusion of Iogenic plasma  

Microsoft Academic Search

The plasma distribution around Io as measured by Voyager 1 displays an asymmetric discontinuity at Io's orbit that has been suggested to be the signature of centrifugally driven interchange diffusion fed by plasma derived from Io. This hypothesis is explored further and found to be valid. The particular form for the diffusion coefficient appropriate to centrifugally driven turbulence is derived.

G. L. Siscoe; Danny Summers

1981-01-01

185

Astronaut Gordon Cooper in centrifuge for tests  

NASA Technical Reports Server (NTRS)

Astronaut L. Gordon Cooper, prime pilot for the Mercury-Atlas 9 mission, is strapped into the gondola while undergoing tests in the centrifuge at the Naval Air Development Center, Johnsville, Pennsylvania. The centrifuge is used to investigate by simulation the pilot's capability to control the vehicle during the actual flight in its booster and reentry profile.

1963-01-01

186

Centrifugal deformations of the gravitational kink  

E-print Network

The Kaluza-Klein reduction of 4d conformally flat spacetimes is reconsidered. The corresponding 3d equations are shown to be equivalent to 2d gravitational kink equations augmented by a centrifugal term. For space-like gauge fields and non-trivial values of the centrifugal term the gravitational kink solutions describe a spacetime that is divided in two disconnected regions.

Paolo Maraner; Jiannis K. Pachos

2008-11-29

187

Centrifugal enhancement of retroviral mediated gene transfer  

Microsoft Academic Search

Centrifugation has been used for many years to enhance infection of cultured cells with a variety of different types of viruses, but it has only recently been demonstrated to be effective for retroviruses (Ho et al. (1993) J. Leukocyte Biol. 53, 208–212; Kotani et al. (1994) Hum. Gene Ther. 5, 19–28). Centrifugation was investigated as a means of increasing the

Alfred B. Bahnsonz; James T. Dunigan; Bora E. Baysal; Trina Mohney; R. Wayne Atchison; Maya T. Nimgaonkar; Edward D. Ball; John A. Barranger

1995-01-01

188

Investigation of a miniature centrifugal fan  

Microsoft Academic Search

A centrifugal fan was designed with a matching centrifugal volute flow channel in order to investigate a numerical simulation with prototype manufacturing, and to compare with experimental results. The fan configuration was developed according to a fan-design theorem. A model P-60 turbojet engine compressor blade design was adopted for the fan aerodynamic analysis and design. The results were verified using

B. J. Tsai; C. L. Wu

2007-01-01

189

Apparatus for centrifugal separation of coal particles  

DOEpatents

A gravimetric cell for centrifugal separation of fine coal by density has a cylindrical body and a butterfly valve or other apparatus for selectively sealing the body radially across the approximate center of the cylinder. A removable top is provided which seals the cylinder in the centrifuge and in unvented areas.

Dickie, William (New Eagle, PA); Cavallaro, Joseph A. (Mt. Keesport, PA); Killmeyer, Richard P. (Pleasant Hills, PA)

1991-01-01

190

Submarine landslide flows simulation through centrifuge modelling  

E-print Network

SUBMARINE LANDSLIDE FLOWS SIMULATION THROUGH CENTRIFUGE MODELLING by Chang Shin GUE A dissertation submitted for the degree of Doctor of Philosophy at the University of Cambridge Churchill College January... “Continuous effort – not strength or intelligence – is the key to unlocking our potential” - Winston Churchill ABSTRACT SUBMARINE LANDSLIDE FLOWS SIMULATION THROUGH CENTRIFUGE MODELLING Chang Shin GUE Landslides occur both onshore...

Gue, Chang Shin

2012-05-08

191

Apparatus for centrifugal separation of coal particles  

SciTech Connect

A gravimetric cell was designed for the centrifugal separation of coal. It has a cylindrical body and a butterfly valve or other apparatus for selectively sealing the body radially across the approximate center of the cylinder. A removable top is provided which seals the cylinder in the centrifuge and in unvented areas. 2 figs.

Dickie, W.; Cavallaro, J.A.; Killmeyer, R.P.

1988-08-30

192

Apparatus for centrifugal separation of coal particles  

SciTech Connect

This patent describes a gravimetric cell for centrifugal separation of fine coal by density which has a cylindrical body and a butterfly valve or other apparatus for selectively sealing the body radially across the approximate center of the cylinder. A removable top is provided which seals the cylinder in the centrifuge and in unvented areas.

Dickie, W.; Cavallaro, J.A.; Killmeyer, R.P.

1991-04-16

193

Centrifugal pump problems--causes and cures  

SciTech Connect

Centrifugal pump problems ranging from unsatisfactory hydraulic performance to noise and mechanical problems are discussed. The contents include: hydraulic performance problems; problems with performance tests; common problems in centrifugal pumps; cavitation; performance at reduced NPSH; liquid-handling systems and special problems; field procedure and remedial steps; and a checklist of frequent problems and causes. (JMT)

Yedidiah, S.

1980-01-01

194

Preventing cavitation in high energy centrifugal pumps  

Microsoft Academic Search

Large-eye impellers for high energy centrifugal pumps were developed to meet the specification of reduced NPSH{sub r} at rated flow conditions. Unfortunately, this improved NPSH performance was not without adverse tradeoffs because an abnormal increase in noise, vibration and cavitation erosion were experienced at low flows. Centrifugal pumps are often used under widely varying and adverse conditions, and in the

A. W. F. Garbers; A. K. Wasfi

1990-01-01

195

Quantum Monte Carlo investigations of density functional theory of the strongly inhomogeneous electron gas  

Microsoft Academic Search

We use a variational quantum Monte Carlo realization of the adiabatic connection technique to calculate the most relevant quantities in Hohenberg-Kohn-Sham density functional theory for several strongly inhomoge- neous electron-gas systems. Results for the coupling-constant dependence of the exchange-correlation energy, the pair-correlation function, the exchange-correlation hole, and the exchange and correlation energy densities are presented. Comparisons are made with the

Maziar Nekovee; W. Foulkes; R. Needs

2003-01-01

196

Quantum Monte Carlo investigations of density functional theory of the strongly inhomogeneous electron gas  

Microsoft Academic Search

We use a variational quantum Monte Carlo realization of the adiabatic connection technique to calculate the most relevant quantities in Hohenberg-Kohn-Sham density functional theory for several strongly inhomogeneous electron-gas systems. Results for the coupling-constant dependence of the exchange-correlation energy, the pair-correlation function, the exchange-correlation hole, and the exchange and correlation energy densities are presented. Comparisons are made with the interaction

Maziar Nekovee; W. M. Foulkes; R. J. Needs

2003-01-01

197

Exact-exchange density-functional theory applied to a strongly inhomogeneous electron gas  

Microsoft Academic Search

A recently developed quasi-two-dimensional exact-exchange formalism within the framework of density-functional theory has been applied to a strongly inhomogeneous interacting electron gas. Results are presented for the exchange-hole density at different positions in the system, the exchange-energy density, and the exchange energy per particle. It has been found that the exact exchange hole is strongly nonlocal when evaluated at a

S. Rigamonti; F. A. Reboredo; C. R. Proetto

2003-01-01

198

Exact-Exchange Density Functional Theory applied to a strongly inhomogeneous electron gas  

Microsoft Academic Search

A recently developed quasi two-dimensional exact-exchange formalism within the framework of Density Functional Theory has been applied to a strongly inhomogeneous interacting electron gas, and the results compared with state-of-the-art Variational Quantum Monte Carlo (VMC) numerical simulations for the same system. These latter results, extremely demanding from the computational point of view, could be considered as a benchmark for the

Santiago Rigamonti; Fernando A. Reboredo; Cesar R. Proetto

2003-01-01

199

Dissociation energy of alkali metal clusters related to inhomogeneous electron gas theory  

Microsoft Academic Search

A pseudopotential model, combined with a one-centre expansion, is set up to calculate the dissociation energies D of alkali metal atom clusters LiN to CsN, when 2 ˇ- N ˇ- 10. This central field model is solved for the valence electrons using the Slater-Kohn-Sham (SKS) equations, with a local density approximation for the exchange-correlation one-body potential. Inhomogeneous electron gas theory,

N. A. Cordero; J. A. Alonso; J. M. López; N. H. March

1993-01-01

200

Dissociation energy of alkali metal clusters related to inhomogeneous electron gas theory  

Microsoft Academic Search

A pseudopotential model, combined with a one-centre expansion, is set up to calculate the dissociation energies D of alkali metal atom clusters LiN to CsN, when 2 ?- N ?- 10. This central field model is solved for the valence electrons using the Slater-Kohn-Sham (SKS) equations, with a local density approximation for the exchange-correlation one-body potential. Inhomogeneous electron gas theory,

N. A. Cordero; J. A. Alonso; J. M. López; N. H. March

1993-01-01

201

Centrifuge Modelling of the Performance of Liquefaction Mitigation Measures for  

E-print Network

Centrifuge Modelling of the Performance of Liquefaction Mitigation Measures for Shallow Foundations Centrifuge Stored Angular Momentum Actuator Equivalent Shear Beam Container Automatic Sand Pourer Hostun Sand Methylcellulose 3 #12;Experimental Techniques and Materials 10 m Turner Beam Centrifuge Stored

202

Influence of the positive prewhirl on the performance of centrifugal pumps with different airfoils  

NASA Astrophysics Data System (ADS)

According to the basic theory of turbomachinery design and inlet guide vanes prewhirl regulation, two different airfoils inlet guide vanes of prewhirl regulation device were designed, the influence of the positive prewhirl to the performance of centrifugal pump were studied based on different airfoils. The results show that, for a single-suction centrifugal pump: Gottingen bowed blade-type inlet guide vane adjustment effect is better than straight blade-type inlet guide; appropriate design of positive prewhirl can elevate the efficiency of centrifugal pumps. Compared with no vane conditions, the efficiency of centrifugal pump with prewhirl vanes has been greatly improved and the power consumption has been reduced significantly, while has little influence on the head.

Zhou, C. M.; Wang, H. M.; Huang, X.; Lin, H.

2012-11-01

203

Rotor for centrifugal fast analyzers  

DOEpatents

The invention is an improved photometric analyzer of the rotary cuvette type, the analyzer incorporating a multicuvette rotor of novel design. The rotor (a) is leaktight, (b) permits operation in the 90/sup 0/ and 180/sup 0/ excitation modes, (c) is compatible with extensively used Centrifugal Fast Analyzers, and (d) can be used thousands of times. The rotor includes an assembly comprising a top plate, a bottom plate, and a central plate, the rim of the central plate being formed with circumferentially spaced indentations. A uv-transmitting ring is sealably affixed to the indented rim to define with the indentations an array of cuvettes. The ring serves both as a sealing means and an end window for the cuvettes.

Lee, N.E.

1984-01-01

204

Centrifuges in gravitational physiology research  

NASA Technical Reports Server (NTRS)

Data from space flight and ground based experiments have clearly demonstrated the importance of Earth gravity for normal physiological function in man and animals. Gravitational Physiology is concerned with the role and influence of gravity on physiological systems. Research in this field examines how we perceive and respond to gravity and the mechanisms underlying these responses. Inherent in our search for answers to these questions is the ability to alter gravity, which is not physically possible without leaving Earth. However, useful experimental paradigms have been to modify the perceived force of gravity by changing either the orientation of subjects to the gravity vector (i.e., postural changes) or by applying inertial forces to augment the magnitude of the gravity vector. The later technique has commonly been used by applying centripetal force via centrifugation.

Ballard, Rodney W.; Davies, Phil; Fuller, Charles A.

1993-01-01

205

Correlation of cavitating centrifugal pumps  

NASA Astrophysics Data System (ADS)

The foreknowledge of the minimum NPSH ('net positive suction head') required for a cavitation-free performance of centrifugal pumps is important for a safe and sound operation of these machines. The required NPSH varies from pump to pump, from fluid to fluid, and from temperature to temperature of the pumped fluid. This is known as the thermodynamic effect. The methods currently used for the correlation and analysis of this condition are not always reliable because of the multi-variable nature of the cavitation process. In this paper, two new methods are proposed which lead to more consistent correlations of the required minimum NPSH; thus they can also be used for more dependable predictions of the net positive suction head for any pump, fluid and temperature. The predictions by the two methods do not coincide, but outline a narrow band of probability, within which the actual test points are invariably located.

Zika, V. J.

1984-06-01

206

Centrifugal membrane filtration -- Task 9  

SciTech Connect

The Energy and Environmental Research Center (EERC) has teamed with SpinTek Membrane Systems, Inc., the developer of a centrifugal membrane filtration technology, to demonstrate applications for the SpinTek technology within the US Department of Energy (DOE) Environmental management (EM) Program. The technology uses supported microporous membranes rotating at high rpm, under pressure, to separate suspended and colloidal solids from liquid streams, yielding a solids-free permeate stream and a highly concentrated solids stream. This is a crosscutting technology that falls under the Efficient Separations and Processing Crosscutting Program, with potential application to tank wastes, contaminated groundwater, landfill leachate, and secondary liquid waste streams from other remediation processes, including decontamination and decommissioning systems. Membrane-screening tests were performed with the SpinTek STC-X4 static test cell filtration unit, using five ceramic membranes with different pore size and composition. Based on permeate flux, a 0.25-{micro}m TiO{sub 2}/Al{sub 2}O{sub 3} membrane was selected for detailed performance evaluation using the SpinTek ST-IIL centrifugal membrane filtration unit with a surrogate tank waste solution. An extended test run of 100 hr performed on a surrogate tank waste solution showed some deterioration in filtration performance, based on flux, apparently due to the buildup of solids near the inner portion of the membrane where relative membrane velocities were low. Continued testing of the system will focus on modifications to the shear pattern across the entire membrane surface to affect improved long-term performance.

NONE

1996-08-01

207

Centrifuge workers study. Phase II, completion report  

SciTech Connect

Phase II of the Centrifuge Workers Study was a follow-up to the Phase I efforts. The Phase I results had indicated a higher risk than expected among centrifuge workers for developing bladder cancer when compared with the risk in the general population for developing this same type of cancer. However, no specific agent could be identified as the causative agent for these bladder cancers. As the Phase II Report states, Phase I had been limited to workers who had the greatest potential for exposure to substances used in the centrifuge process. Phase II was designed to expand the survey to evaluate the health of all employees who had ever worked in Centrifuge Program Departments 1330-1339 but who had not been interviewed in Phase I. Employees in analytical laboratories and maintenance departments who provided support services for the Centrifuge Program were also included in Phase II. In December 1989, the Oak Ridge Associated Universities (ORAU), now known as Oak Ridge Institute for Science and Education (ORISE), was contracted to conduct a follow-up study (Phase II). Phase H of the Centrifuge Workers Study expanded the survey to include all former centrifuge workers who were not included in Phase I. ORISE was chosen because they had performed the Phase I tasks and summarized the corresponding survey data therefrom.

Wooten, H.D.

1994-09-01

208

Internally-cooled centrifugal compressor with cooling jacket formed in the diaphragm  

DOEpatents

An internally-cooled centrifugal compressor having a shaped casing and a diaphragm disposed within the shaped casing having a gas side and a coolant side so that heat from a gas flowing though the gas side is extracted via the coolant side. An impeller disposed within the diaphragm has a stage inlet on one side and a stage outlet for delivering a pressurized gas to a downstream connection. The coolant side of the diaphragm includes at least one passageway for directing a coolant in a substantially counter-flow direction from the flow of gas through the gas side.

Moore, James J.; Lerche, Andrew H.; Moreland, Brian S.

2014-08-26

209

Tautochronic centrifugal pendulum vibration absorbers. General design and analysis  

NASA Astrophysics Data System (ADS)

Since the 1930s, centrifugal pendulum vibration absorbers have been used in rotating and reciprocating machinery for the attenuation of torsional vibrations. A large variety of absorber types were suggested and the design was done by linearization theory until the introduction of the tautochronic bifilar pendulum absorbers. Since then, the performance and dynamic stability of this specific absorber type have been considered in analytical and numerical investigations. Different perturbations, e.g. nonlinear mistuning, were considered in order to optimize the system performance, but the characteristic bifilar design remained unchanged. In this paper, a general approach for the design of tautochronic pendulum vibration absorbers is proposed. As a result, it is possible to deal with a large variety of non-bifilar centrifugal vibration absorber designs which provide application-related optimal performance and resolve some of the existing design limitations. Established analytic predictions that show a satisfactory agreement with numerical as well as experimental investigations for bifilar absorbers are not applicable for the comparison of different tautochronic absorbers. Therefore, the second part of this work shows how to analyze this class of centrifugal vibration absorbers using a Hamiltonian formulation. Successive canonical transformations lead to nonlinear equations in action-angle variables, which are then approximated to first order and analyzed by using the method of averaging. These results provide a basis for the design and analysis of tautochronic bifilar and non-bifilar vibration absorbers.

Mayet, J.; Ulbrich, H.

2014-02-01

210

On reversal of centrifugal acceleration in special relativity  

E-print Network

The basic principles of General Theory of Relativity historically have been tested in gedanken experiments in rotating frame of references. One of the key issues, which still evokes a lot of controversy, is the centrifugal acceleration. Machabeli & Rogava (1994) argued that centrifugal acceleration reverse direction for particles moving radially with relativistic velocities within a "bead on a wire" approximation. We show that this result is frame-dependent and reflects a special relativistic dilution of time (as correctly argued by de Felice (1995)) and is analogous to freezing of motion on the black hole horizon as seen by a remote observer. It is a reversal of coordinate acceleration; there is no such effect as measured by a defined set of observers, e.g., proper and/or comoving. Frame-independent velocity of a "bead" with respect to stationary rotating observers increases and formally reaches the speed of light on the light cylinder. In general relativity, centrifugal force does reverse its direction at photon circular orbit, r=3M in Schwarzschild metric, as argued by Abramowicz (1990).

Maxim Lyutikov

2009-03-05

211

Plasma instability of a vacuum arc centrifuge.  

PubMed

Ever since conception of the vacuum arc centrifuge in 1980, periodic fluctuations in the ion saturation current and floating potential have been observed in Langmuir probe measurements in the rotation region of a vacuum arc centrifuge. In this work we develop a linearized theoretical model to describe a range of instabilities in the vacuum arc centrifuge plasma column, and then test the validity of the description through comparison with experiment. We conclude that the observed instability is a "universal" instability, driven by the density gradient, in a plasma with finite conductivity. PMID:12006025

Hole, M J; Dallaqua, R S; Simpson, S W; Del Bosco, E

2002-04-01

212

Analytical theory relating the depth of the sulfate-methane transition to gas hydrate distribution and saturation  

Microsoft Academic Search

We develop a theory that relates gas hydrate saturation in marine sediments to the depth of the sulfate-methane transition (SMT) zone below the seafloor using steady state, analytical expressions. These expressions are valid for systems in which all methane transported into the gas hydrate stability zone (GHSZ) comes from deeper external sources (i.e., advective systems). This advective constraint causes anaerobic

Gaurav Bhatnagar; Sayantan Chatterjee; Walter G. Chapman; Brandon Dugan; Gerald R. Dickens; George J. Hirasaki

2011-01-01

213

Gas production in the Barnett Shale obeys a simple scaling theory  

PubMed Central

Natural gas from tight shale formations will provide the United States with a major source of energy over the next several decades. Estimates of gas production from these formations have mainly relied on formulas designed for wells with a different geometry. We consider the simplest model of gas production consistent with the basic physics and geometry of the extraction process. In principle, solutions of the model depend upon many parameters, but in practice and within a given gas field, all but two can be fixed at typical values, leading to a nonlinear diffusion problem we solve exactly with a scaling curve. The scaling curve production rate declines as 1 over the square root of time early on, and it later declines exponentially. This simple model provides a surprisingly accurate description of gas extraction from 8,294 wells in the United States’ oldest shale play, the Barnett Shale. There is good agreement with the scaling theory for 2,057 horizontal wells in which production started to decline exponentially in less than 10 y. The remaining 6,237 horizontal wells in our analysis are too young for us to predict when exponential decline will set in, but the model can nevertheless be used to establish lower and upper bounds on well lifetime. Finally, we obtain upper and lower bounds on the gas that will be produced by the wells in our sample, individually and in total. The estimated ultimate recovery from our sample of 8,294 wells is between 10 and 20 trillion standard cubic feet. PMID:24248376

Patzek, Tad W.; Male, Frank; Marder, Michael

2013-01-01

214

Two-Stage Centrifugal Fan  

NASA Technical Reports Server (NTRS)

Fan designs are often constrained by envelope, rotational speed, weight, and power. Aerodynamic performance and motor electrical performance are heavily influenced by rotational speed. The fan used in this work is at a practical limit for rotational speed due to motor performance characteristics, and there is no more space available in the packaging for a larger fan. The pressure rise requirements keep growing. The way to ordinarily accommodate a higher DP is to spin faster or grow the fan rotor diameter. The invention is to put two radially oriented stages on a single disk. Flow enters the first stage from the center; energy is imparted to the flow in the first stage blades, the flow is redirected some amount opposite to the direction of rotation in the fixed stators, and more energy is imparted to the flow in the second- stage blades. Without increasing either rotational speed or disk diameter, it is believed that as much as 50 percent more DP can be achieved with this design than with an ordinary, single-stage centrifugal design. This invention is useful primarily for fans having relatively low flow rates with relatively high pressure rise requirements.

Converse, David

2011-01-01

215

Improved return passages for multistage centrifugal compressors  

E-print Network

This thesis presents a design concept for return passages in multistage centrifugal compressors. Flow in a baseline return passage is analyzed to identify loss sources that have substantial potential for reduction. For the ...

Glass, Benjamin W., S.M. Massachusetts Institute of Technology

2010-01-01

216

A methodology for centrifugal compressor stability prediction  

E-print Network

The stable operation of centrifugal compressors is limited by well-known phenomena, rotating stall and surge. Although the manifestation of the full scale instabilities is similar to the ones observed in axial machines, ...

Benneke, Björn

2009-01-01

217

Astronaut Virgil Grissom preparing for centrifuge training  

NASA Technical Reports Server (NTRS)

Astronaut Virgil I. (Gus) Grissom, wearing the new Mercury pressure suit, is preparing for centrifuge training. He is talking with Astronaut L. Gordon Cooper and two others before the training session.

1961-01-01

218

21 CFR 864.5350 - Microsedimentation centrifuge.  

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology Devices § 864.5350 Microsedimentation centrifuge. (a)...

2014-04-01

219

21 CFR 864.5350 - Microsedimentation centrifuge.  

Code of Federal Regulations, 2012 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology Devices § 864.5350 Microsedimentation centrifuge. (a)...

2012-04-01

220

21 CFR 864.5350 - Microsedimentation centrifuge.  

Code of Federal Regulations, 2013 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology Devices § 864.5350 Microsedimentation centrifuge. (a)...

2013-04-01

221

Paper No. : 0317 LATERAL SPREADING DURING CENTRIFUGE MODEL  

E-print Network

Paper No. : 0317 LATERAL SPREADING DURING CENTRIFUGE MODEL EARTHQUAKES Stuart K. Haigh1 , S sand marker lines within centrifuge models. A series of dynamic centrifuge model tests have been these free boundaries from previous earthquakes. Dynamic centrifuge modelling was carried out using sloping

Haigh, Stuart

222

Thin-shell wormholes with a generalized Chaplygin gas in Einstein-Born-Infeld theory  

E-print Network

We construct spherically symmetric thin-shell wormholes supported by a generalized Chaplygin gas in Born-Infeld electrodynamics coupled to Einstein gravity, and we analyze their stability under radial perturbations. For different values of the Born-Infeld parameter and the charge, we compare the results with those obtained in a previous work for Maxwell electrodynamics. The stability region in the parameter space reduces and then disappears as the value of the Born-Infeld parameter is modified in the sense of a larger departure from Maxwell theory.

Ernesto F. Eiroa; Griselda Figueroa Aguirre

2012-05-11

223

Trace gas exchange and the validity of similarity theory in the roughness sublayer above forests  

NASA Astrophysics Data System (ADS)

This thesis is an investigation of (1) methane (CH4) and nitrous oxide (N2O) exchange above a boreal aspen (Populus tremuloides) stand near Prince Albert, Saskatchewan, and (2) the similarity theory upon which the flux measurements were based. Although CH4 and N2O play significant roles in the atmosphere, estimates of their global source and sink strengths are only poorly constrained. Boreal ecosystems are a priority trace gas research area, and the CH4 and N2O exchanges were measured as part of the Boreal Ecosystem-Atmosphere Study (BOREAS). The fluxes were determined micrometeorologically using laser-based Trace Gas Analysis Systems (TGAS). Between April and September, 1994, a mean net CH4 emission of 15.7 ± 2.8 ng m-2 s-1 was measured from a tower above the aspen stand. The CH4 emissions peaked in late summer, and the CH4 flux and soil temperature correlated with r2 = 0.70. In contrast, CH4 uptake was recorded near the tower base. Overall, it appears that CH4 emissions from anoxic patches located throughout the above-canopy footprint overwhelmed uptake from drier areas to yield a net emission of CH4. The mean N2O emission of 1.4 ± 0.7 ng m-2 s-1 was attributable to low soil nitrate (NO3/sp-) and ammonium (NH4+) availability. The small CH4 and N2O fluxes required that they be determined using a flux-gradient approach based upon similarity theory. However, similarity theory has been reported to severely underestimate scalar fluxes in the roughness sublayer above forests. Accordingly, the validity of similarity theory was investigated above a mixed deciduous forest at Camp Borden, Ontario, between July and October 1995. The TGAS used in the research enabled a higher resolution measurement than has been previously possible in similarity theory investigations. Between 1.9 and 2.2 canopy heights (hc), the mean enhancement factor (the ratio of independent fluxes to similarity theory values) was 1.15 ± 0.07. Closer to the canopy (1.2 to 1.4 hc), mean enhancement factors of 1.61 ± 0.10 and 1.82 ± 0.11 were measured, before and after leaf senescence, respectively. Overall, it appears that similarity theory can be used within the roughness sublayer of forests with a greater confidence than previously has been believed.

Simpson, Isobel Jane

1997-11-01

224

Renal Response to Chronic Centrifugation in Rats  

NASA Technical Reports Server (NTRS)

Previously reported effects of chronic centrifugation on renal function in mammals are contradictory. The present study was conducted as an effort to provide a comprehensive analysis of renal response to chronic centrifugation (12 days at +2 Gz). Sixteen male Sprague-Dawley rats (210-230 g) were used: eight centrifuged (EC) and eight off centrifuge controls (OCC). During centrifugation EC had lower body weight and food consumption. EC showed a decrease (72%) in water intake for the first two days (T1 and T2) followed by significant increases from T4-T6. EC urine output increased two-fold over the first four days, returning to baseline by T9. EC urea excretion was elevated on T3 through T5. Creatinine, Na(+), K(+), and osmolar excretion were lower than OCC over the last four days of the study. Assuming constant plasma osmolarity and creatinine levels, EC free water clearance (C(sub H2O)) was elevated significantly on T4 when the peak urine output was exhibited. EC also had a greater C(sub H2O) over the last four days, associated with a significantly lower osmolar clearance and GFR. The initial diuresis exhibited during centrifugation can be attributed to a reduced water resorption and increased urea excretion. This diuresis was mediated independent of changes in GFR over the first eight days. However, differences in excretion seen after eight days of centrifugation are probably GFR mediated which would imply animals established a new homeostatic setpoint by that time. Centrifugation elicites an acute alteration in fluid homeostasis followed by adaptation within a week.

Ortiz, Rudy M.; Wang, T. J.; Corbin, B. J.; Wade, C. E.; Hargens, Alan R. (Technical Monitor)

1996-01-01

225

Theory versus experiment for the rotordynamic coefficients of labyrinth gas seals. II - A comparison to experiment  

NASA Technical Reports Server (NTRS)

An experimental test facility is used to measure the leakage and rotordynamic coefficients of teeth-on-rotor and teeth-on-stator labyrinth gas seals. The test results are presented along with the theoretically predicted values for the two seal configurations at three different radial clearances and shaft speeds to 16,000 cpm. The test results show that the theory accurately predicts the cross-coupled stiffness for both seal configurations and shows improvement in the prediction of the direct damping for the teeth-on-rotor seal. The theory fails to predict a decrease in the direct damping coefficient for an increase in the radial clearance for the teeth-on-stator seal.

Childs, D. W.; Scharrer, J. K.

1987-01-01

226

Three-Level Maser Action in Gas I. Theory of Multiple Quantum Transition and Doppler Effect in Three-Level Gas Maser  

Microsoft Academic Search

The multiple quantum process in the off-resonant condition of the three-level gas maser is discussed. The intensity of the emission produced by this process is calculated by a perturbation theory and also by a more general treatment which is the application of Javan's theory to the off-resonant case. Some graphical representations of the signal line under off-resonant pumping are given

Tatsuo Yajima

1961-01-01

227

Renormalization Theory of a Two Dimensional Bose Gas: Quantum Critical Point and Quasi-Condensed State  

NASA Astrophysics Data System (ADS)

We present a renormalization group construction of a weakly interacting Bose gas at zero temperature in the two-dimensional continuum, both in the quantum critical regime and in the presence of a condensate fraction. The construction is performed within a rigorous renormalization group scheme, borrowed from the methods of constructive field theory, which allows us to derive explicit bounds on all the orders of renormalized perturbation theory. Our scheme allows us to construct the theory of the quantum critical point completely, both in the ultraviolet and in the infrared regimes, thus extending previous heuristic approaches to this phase. For the condensate phase, we solve completely the ultraviolet problem and we investigate in detail the infrared region, up to length scales of the order (? ^3? _0)^{-1/2} (here ? is the interaction strength and ? _0 the condensate density), which is the largest length scale at which the problem is perturbative in nature. We exhibit violations to the formal Ward Identities, due to the momentum cutoff used to regularize the theory, which suggest that previous proposals about the existence of a non-perturbative non-trivial fixed point for the infrared flow should be reconsidered.

Cenatiempo, S.; Giuliani, A.

2014-07-01

228

Numerical study of a swirled turbulent flow in the separation zone of a centrifugal air separator  

Microsoft Academic Search

A mathematical model of a swirled turbulent flow in the separation zone of a pneumatic centrifugal device is presented. The model is based on the known k-? model of turbulence proposed by Wilcox. The influence of rotation of the separation-zone walls, input swirl of the gas flow, and other characteristic parameters on the mean velocity field is demonstrated. A comparison

A. V. Shvab; P. N. Zyatikov; Sh. R. Sadretdinov; A. G. Chepel

2010-01-01

229

Centrifugation in water Drying in a 37 degree Celsius  

E-print Network

1 Centrifugation in water Drying in a 37 degree Celsius After some days the different phases were) CENTRIFUGATION CENTRIFUGATION 3 days in 40ml of water Then 20 ml of Butanol CENTRIFUGATION 3 days in 40 ml of 0.1 M Na OH Water. Then 20 ml of Butanol CENTRIFUGATION 3 days in 40 ml of HCL Water pH 5-6 Then 20 ml

Paris-Sud XI, Université de

230

Supersonic COIL driven by centrifugal bubbling SOG with efficient depletion of chemicals in single pass  

NASA Astrophysics Data System (ADS)

An efficient and compact centrifugal bubbling SOG was employed as energy source in supersonic COIL. A centrifugal bubbling SOG generated gas at 100 torr of total pressure providing 90% of chlorine utilization and 60% of O2(1?) yield with efficient depletion of BHP chemicals in single pass through SOG. A 1 kW class ejector COIL powered by this SOG demonstrated a specific power of 12.5 W per 1cm3/s of BHP volumetric rate at chemical efficiency 22.7%.

Zagidullin, Marsel V.; Nikolaev, Valery D.; Khvatov, Nikolay A.; Svistun, Michael I.

2008-10-01

231

Lattice gas with random-site energies and theory of novel amorphous metal hydride phase  

NASA Astrophysics Data System (ADS)

A lattice gas with random-site energies is investigated as a model for hydrogen in amorphous metals. The author's recent theory for calculating the chemical potential in a system with many competing interactions is modified to include the random-site energies. Results are qualitatively different from those recently presented by Griessen using simple mean-field (MF) theory. Whereas MF theory predicts no phase separation above a critical value of the site energy width ?, the present model gives a finite critical temperature Tc?1? for large ?. It also predicts the critical concentration to decrease proportionally to 1?2 and yields a closed-loop, retrograde-solubility phase diagram. Thus, analogous to binary liquids with orientation-dependent interactions, there is a maximum concentration above which no phase separation occurs. For interactions and spread in site energy expected for Pd-based amorphous hydrides, the critical temperature is predicted to be approximately 200-250 K, which may be detectable by heat-capacity or spectroscopic techniques even if it is too low for pressure-versus-composition studies.

Richards, Peter M.

1984-11-01

232

TIR-Based Dynamic Liquid-Level and Flow-Rate Sensing and its Application on Centrifugal Microfluidic Platforms  

Microsoft Academic Search

For the first time we present a technique for the spatio-temporally resolved localization of liquid-gas interfaces on centrifugal microfluidic platforms based on total internal reflection (TIR) at the channel wall. The simple setup consists of a line laser and a linear image sensor array mounted in a stationary instrument. Apart from identifying the presence of (usually unwanted) gas bubbles, the

J. Hoffmann; L. Riegger; D. Mark; F. von Stetten; R. Zengerle; J. Ducree

2009-01-01

233

Neurovestibular effects of bed rest and centrifugation.  

PubMed

Subjective body position, as influenced by 21-day 6 degrees -head-down bed rest and intermittent supine centrifugation, was investigated in two experimental groups. Treatment subjects were exposed to a daily dose of 1-hour of horizontal centrifugation, whereas control subjects were also put on the centrifuge, but were not spun. During the centrifuge runs subjects were exposed to a constant gradient with 1-G(z) at the heart and 2.5-G(z) at the feet. Subjects reported their subjective postural position (SPP) before, during and after each 1-hour centrifuge exposure. We find that subjects shift their frame of reference over the first week of bed rest and perceive the 6 degrees -head-down position as horizontal. Spinning shifts the SPP by about 30 degrees towards an upright position, consistent with the angle of the gravito-inertial vector positioned close to the vestibular system. The SPP estimates for the upper and lower body failed to reflect the massive gravity gradient between head and feet, and subjects generally reported a single tilt for the whole body. PMID:20555166

Jarchow, T; Young, L R

2010-01-01

234

Liquid centrifugation for nuclear waste partitioning  

SciTech Connect

The performance of liquid centrifugation for nuclear waste partitioning is examined for the Accelerator Transmutation of Waste Program currently under study at the Los Alamos National Laboratory. Centrifugation might have application for the separation of the LiF-BeF{sub 2} salt from heavier radioactive materials fission product and actinides in the separation of fission product from actinides, in the isotope separation of fission-product cesium before transmutation of the {sup 137}Cs and {sup 135}Cs, and in the removal of spallation product from the liquid lead target. It is found that useful chemical separations should be possible using existing materials for the centrifuge construction for all four cases with the actinide fraction in fission product perhaps as low as 1 part in 10{sup 7} and the fraction of {sup 137}CS in {sup 133}Cs being as low as a few parts in 10{sup 5}. A centrifuge cascade has the advantage that it can be assembled and operated as a completely closed system without a waste stream except that associated with maintenance or replacement of centrifuge components.

Bowman, C.D.

1992-03-11

235

Stop-motion illuminator for centrifuges  

NASA Astrophysics Data System (ADS)

The majority of laboratory centrifuges have no provisions for observation of the process of sedimentation and fractionation which goes on in the test tube in the darkness of a "black box." Some centrifuges have a transparent cover or a magnifier in the cover to watch a blurred picture of the layers in the moving test tube which provides little information. The stop-motion effect with the test tube can a priori be based on either mechanical or electronic stroboscopy. To implement the mechanical stroboscopy, a standard microscope illuminator with a diaphragm is attached to the wall of the centrifuge. Through a hole in the wall the illuminator projects a cone of light with the diameter 0.1 mm at the top of the cone. The cone intersects with a 0.1 mm hole in the test-tube holder. The test tube is illuminated at the moment of intersection. Its content is observed through a magnifier on the cover of the centrifuge. The holder has a cut-out window to see the test tube. The flash at the hole-beam intersection is 0.5 ?s, which is many times shorter than the duration of a xenon-tube stroboscopic flash (10-20 ?s). This is the main reason why industrial stroboscopes cannot be used for stop-motion illumination in a centrifuge.

Moroz, Pavel E.

1999-11-01

236

Gas  

MedlinePLUS

... swallow and the breakdown of undigested food by bacteria in the large intestine. Certain foods may cause gas. Foods that produce gas in one person may not cause gas in another. You can reduce the amount of gas you have by Drinking lots of water and non-fizzy drinks Eating more slowly so ...

237

Centrifugal separation and equilibration dynamics in an electron-antiproton plasma  

E-print Network

Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally-separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally-separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.

G. B. Andresen; M. D. Ashkezari; M. Baquero-Ruiz; W. Bertsche; P. D. Bowe; E. Butler; C. L. Cesar; S. Chapman; M. Charlton; A. Deller; S. Eriksson; J. Fajans; T. Friesen; M. C. Fujiwara; D. R. Gill; A. Gutierrez; J. S. Hangst; W. N. Hardy; M. E. Hayden; A. J. Humphries; R. Hydomako; S. Jonsell; N. Madsen; S. Menary; P. Nolan; A. Olin; A. Povilus; P. Pusa; F. Robicheaux; E. Sarid; D. M. Silveira; C. So; J. W. Storey; R. I. Thompson; D. P. van der Werf; J. S. Wurtele; Y. Yamazaki

2011-04-26

238

Ion fractionation at the surface of aqueous inorganic salt solutions by means of a ‘film centrifuge  

NASA Astrophysics Data System (ADS)

The predictions of Gibbs's law and the electrolyte theory about the (negative) adsorption of salts on the surface of aqueous salt solutions are compared with the results of an analysis of very thin surface films skimmed by means of a `film centrifuge' from a solution containing two different salts. The separation effects observed on the salt mixtures CsCl/NaCl, BaCl2/ NaCl, BaCl2/CsCl, and SrCl2/CsCl differ greatly from theoretical results, but they agree with results observed by the so-called bubble process. The centrifuge and the analytical methods are briefly described.

Koske, P. H.; Martin, H.

1972-09-01

239

Effects of chronic centrifugation on mice  

NASA Technical Reports Server (NTRS)

Previous studies have shown that exposure to excess gravity in vitro alters the developmental sequence in embryonic mouse limbs and palates (Duke, Janer and Campbell, 1984; Duke, 1983). The effects of excess gravity on in vivo mammalian development was investigated using a small animal centrifuge. Four-week old female mice exposed to excess gravities of 1.8-3.5 G for eight weeks weighed significantly less than controls. Mice were mated after five weeks of adaptation to excess G, and sacrificed either at gestational day 12 or 18. There were fewer pregnancies in the centrifuged group (4/36) than in controls (9/31), and crown rump lengths (CRL) of embryos developing in the centrifuge were less than CRLs of 1-G embryos. These results show that although immersed in amniotic fluid, embryos are responsive to Delta-G.

Janer, L.; Duke, J.

1984-01-01

240

The geotechnical centrifuge in offshore engineering  

SciTech Connect

One of the greatest needs in offshore geotechnical engineering is for large scale test measurements on which to calibrate design procedures. The geotechnical centrifuge offers at least a partial remedy. Because it allows one to properly simulate stresses, it is a legitimate, relatively inexpensive option to full scale field testing. As such it is a valuable technique and can be an excellent complement to laboratory tests, 1-g model tests and numerical analyses. However, it has not been widely used by industry even though the capability has existed for almost thirty years. This paper argues that this technology should gain acceptance beyond the research community. The paper presents an overview of centrifuge principles, philosophies of use, and limitations of the technique. For illustration, several actual applications of centrifuge testing for complex offshore problems are described. Results are shown to provide important insights into prototype behavior and to agree well with full scale measurements where these are available.

Murff, J.D.

1996-12-31

241

Preventing cavitation in high energy centrifugal pumps  

SciTech Connect

Large-eye impellers for high energy centrifugal pumps were developed to meet the specification of reduced NPSH{sub r} at rated flow conditions. Unfortunately, this improved NPSH performance was not without adverse tradeoffs because an abnormal increase in noise, vibration and cavitation erosion were experienced at low flows. Centrifugal pumps are often used under widely varying and adverse conditions, and in the case of high energy and large-eye impeller pumps, these conditions should be evaluated very carefully. At petrochemical complexes in Secunda in the Republic of South Africa, a centrifugal pump application for lean carbonate solution experienced frequent failures. An investigation and literature survey indicated the cause was low flow cavitation. The purpose of this article is but to give design guidelines as obtained from literature and experience.

Garbers, A.W.F.; Wasfi, A.K. (Sastech Engineering Services (Pty) Ltd. (ZA))

1990-07-01

242

A normal mode theory of capacitive radio frequency discharges between parallel electrodes under diffusion and recombination gas-discharge regimes  

Microsoft Academic Search

A normal mode theory of standard capacitive rf discharges between parallel electrodes is achieved in terms of electron plasma wave resonances by solving electrostatic fluid equations under so-called linear-diffusion and nonlinear-recombination gas-discharge regimes for a wide gas-pressure range. The rf plasma is produced by the main resonance and also by another new and lowest resonance of the electron plasma wave.

S. Nonaka; S. Tsuge

2000-01-01

243

Electromigration in a quasi-two-dimensional electron gas: Theory of driving force  

NASA Astrophysics Data System (ADS)

We calculate the effective force on an impurity charge present in a quasi-two-dimensional electron layer and the induced charge density around the impurity when an electrostatic field is applied parallel to the layer. Our calculation is based on the quantum-mechanical density-matrix formalism, and the scattering is treated in a weak-charge relaxation-time approximation. Our results are compared with the corresponding results in a three-dimensional electron gas, and implications of these results are discussed. It is found that the driving force for electromigration is well approximated by the Fiks-Huntington ballistic theory when KfL>>1, where Kf is the Fermi wave vector and L is the electron mean free path in the layer. For the Si(100) inversion layer, there are significant corrections to the ballistic expression for KfL<=10.

Dasgupta, Basab B.; Sorbello, Richard S.

1980-05-01

244

Effects of buoyancy on gas-jet diffusion flames: Experiment and theory  

NASA Astrophysics Data System (ADS)

Theoretical and experimental research on the effects of buoyancy on gas-jet diffusion flames is described in this paper. Part of this research involves an assessment of existing data obtained under reduced-gravity conditions. The results show that uncertainties in our understanding of flame structure exist and further research is required before reliable predictions of ignition, stabilization and propagation of flames under microgravity conditions can be made. Steady-state and transient theories have been developed and used in the analysis of existing drop-tower data and new data obtained from a stationary experiment involving inverted flames. The result of this research has led to the definition of a microgravity experiment to be performed in space.

Edelman, R. B.; Bahadori, M. Y.

245

Effects of Centrifuge Diameter and Operation on Rodent Adaptation to Chronic Centrifugation  

NASA Technical Reports Server (NTRS)

This study examined the responses of rats to centrifugation in a constant acceleration field (1.5 G). Centrifuge diameter (1.8m, 2.5m or 6.0m) and schedule of operation (Daily or weekly stop) varied between groups. Body mass, food consumption, water consumption and neurovestibular function were measured weekly. Body temperature and activity were continuously monitored using telemetry. A subset of subjects were videotaped (50 minutes per day) to allow for movement analysis. Exposure to a hyperdynamic field of this magnitude did cause the expected depression in the physiological variables monitored. Recovery was accomplished within a relatively rapid time frame; all variables returned to precentrifugation levels. In general, the magnitudes of the changes and the rate of recovery were similar at different centrifuge diameters and stopping frequency. There were cases, however, in which the magnitude of the response and/or the rate of recovery to a new steady-state were altered as a result of centrifuge diameter. In summary, these results indicate that stopping frequency has little, if any, effect on adaptation to chronic centrifugation. However, the angular velocity (omega), and therefore centrifuge diameter is an important consideration in the adaptation of an organism to chronic centrifugation.

Fuller, Charles A.

1997-01-01

246

Effects of Centrifuge Diameter and Operation on Rodent Adaptation to Chronic Centrifugation  

NASA Technical Reports Server (NTRS)

This study examined the responses of rats to centrifugation in a constant acceleration field (1.5 G). Centrifuge diameter (1.8m, 2.5m or 6.0m) and schedule of operation (Daily or weekly stop) varied between groups. Body mass, food consumption, water consumption and neurovestibular function were measured weekly. Body temperature and activity were continuously monitored using telemetry. A subset of subjects were videotaped (50 minutes per day) to allow for movement analysis. Exposure to a hyperdynamic field of this magnitude did cause the expected depression in the physiological variables monitored. Recovery was accomplished within a relatively rapid time frame; all variables returned to precentrifugation levels. In general, the magnitudes of the changes and the rate of recovery were similar at different centrifuge diameters and stopping frequency. There were cases, however, in which the magnitude of the response and/or the rate of recovery to a new steady-state were altered as a result of centrifuge diameter. In summary, these results indicate that stopping frequency has little, if any, effect on adaptation to chronic centrifugation. However, the angular velocity (omega), and therefore centrifuge diameter is an important consideration in the adaptation of an organism to chronic centrifugation.

Fuller, Charles A.

1992-01-01

247

Sperm cleanup and centrifugation processing for cryopreservation.  

PubMed

Fertility rates with artificial insemination are highest with good-quality sperm samples. Therefore, nonviable sperm, cellular debris, and seminal plasma are preferably removed from semen samples prior to use or for preservation. Such compounds are sources where reactive oxygen species are generated during storage or upon cryopreservation, impairing sperm function. In this chapter we describe methods to remove seminal plasma and cellular debris from sperm samples, and for selecting morphologically normal motile sperm. The methods that are described here include: ordinary centrifugation, sperm swim-up, glass wool and Sephadex filtration/adherence, and single-layer as well as discontinuous two-layer iodixanol density gradient centrifugation. PMID:25428016

Sieme, Harald; Oldenhof, Harriëtte

2015-01-01

248

Transport Phenomena in Zonal Centrifuge Rotors  

PubMed Central

An analysis is presented for the evaluation of velocity components and shear-stress distributions of fluid in zonal centrifuge rotors during acceleration. Analytical expressions for the distribution of tangential and radial velocity components and the tangential shear-stress and the radial shear-stress distributions of fluid are obtained for the transient case. Characteristics of each distribution for a typical density gradient liquid in a zonal centrifuge rotor are computed from the relations derived, and are presented as figures. An unusual phenomenon—the tangential velocity of the gradient exceeding the velocity of the rotor during a particular period of acceleration—is demonstrated. PMID:5678322

Hsu, H. W.

1968-01-01

249

Lattice model theory of the equation of state covering the gas, liquid, and solid phases  

NASA Technical Reports Server (NTRS)

The three stable states of matter and the corresponding phase transitions were obtained with a single model. Patterned after Lennard-Jones and Devonshires's theory, a simple cubic lattice model containing two fcc sublattices (alpha and beta) is adopted. The interatomic potential is taken to be the Lennard-Jones (6-12) potential. Employing the cluster variation method, the Weiss and the pair approximations on the lattice gas failed to give the correct phase diagrams. Hybrid approximations were devised to describe the lattice term in the free energy. A lattice vibration term corresponding to a free volume correction is included semi-phenomenologically. The combinations of the lattice part and the free volume part yield the three states and the proper phase diagrams. To determine the coexistence regions, the equalities of the pressure and Gibbs free energy per molecule of the coexisting phases were utilized. The ordered branch of the free energy gives rise to the solid phase while the disordered branch yields the gas and liquid phases. It is observed that the triple point and the critical point quantities, the phase diagrams and the coexistence regions plotted are in good agreement with the experimental values and graphs for argon.

Bonavito, N. L.; Tanaka, T.; Chan, E. M.; Horiguchi, T.; Foreman, J. C.

1975-01-01

250

Boundary-driven nonequilibrium gas flow in a grooved channel via kinetic theory  

NASA Astrophysics Data System (ADS)

The nonequilibrium flow of a gas in a two-dimensional grooved channel, due to the motion of the wall of the channel, is investigated based on kinetic theory. The presence of the rectangular grooves that are placed periodically on the stationary wall results in a two-dimensional flow pattern. The problem is modeled by the linearized Bhatnagar-Gross-Krook (BGK) and S-model kinetic equations, which are solved for the corresponding perturbed distribution functions by the discrete velocity method. Maxwell diffuse type reflecting boundary conditions are used to model the gas-surface interaction, while periodic boundary conditions are imposed at the inlet and outlet of the channel. The computed macroscopic quantities of practical interest include velocity profiles, contours of pressure, density, and temperature, as well as the flow rate and the heat flux through the channel and the drag coefficient along the moving boundary. The results are valid in the whole range of the Knudsen number, from the free molecular regime through the transition and slip regimes up to the hydrodynamic limit, for various values of the depth and the width of the groove and the periodic length of the channel. A comparison between the BGK and S-model results is performed. Several interesting flow patterns and characteristics are examined in terms of the geometrical parameters of the flow configuration, including an unexpected behavior of the velocity profile across the channel at large Knudsen numbers.

Naris, Steryios; Valougeorgis, Dimitris

2007-06-01

251

Aerodynamic performance of centrifugal compressors  

SciTech Connect

Saving money with an efficient pipeline system design depends on accurately predicting compressor performance and ensuring that it meets the manufacturer's guaranteed levels. When shop testing with the actual gas is impractical, an aerodynamic test can ascertain compressor efficiency, but the accuracy and consistency of data acquisition in such tests is critical. Low test-pressure levels necessitate accounting for the effects of Reynolds number and heat transfer. Moreover, the compressor user and manufacturer must agree on the magnitude of the corrections to be applied to the test data.

Sayyed, S.

1981-12-01

252

A theory of a curved vapor-liquid separation boundary: The lattice gas model  

NASA Astrophysics Data System (ADS)

Molecular theory of curved vapor-liquid interphase boundaries was considered in terms of the lattice gas model. The theory uses the quasi-thermodynamic concept of curved layers of a separation boundary with a large radius. The transition from a rectangular lattice to such layers is performed by the introduction of a variable number of the nearest neighbors. The problems (1) of the transition from distributed molecular models to layer models reflecting macroscopic symmetry of the interphase boundary and (2) of a minimum linear size of the surface region to which thermodynamic approaches are applicable were considered. Equations for the quasi-equilibrium distribution of molecules at the vapor-liquid boundary in a metastable system were constructed in the quasi-chemical approximation taking into account direct correlations between the nearest interacting molecules. A metastable state is maintained by a pressure jump described by the macro-scopic Laplace equation on a separation surface inside the interphase region. Equations for local mean pressure values and normal and tangential pressure tensor components inside the interphase region were constructed. These equations were used to obtain microscopic difference mechanical equilibrium equations for curved boundaries of spherical and cylindrical drops in the metastable state. The relation between the micro-scopic difference mechanical equilibrium equations and similar differential equations and the macroscopic Laplace equation, which described pressure jump in a metastable system, was considered. Various definitions of surface tension are discussed.

Tovbin, Yu. K.

2010-02-01

253

Gas phase UV spectrum of a Cu(II)-bis(benzene) sandwich complex: experiment and theory.  

PubMed

Photofragmentation with tunable UV radiation has been used to generate a spectrum for the copper-bis(benzene) complex, [Cu(C6H6)2](2+), in the gas phase. The ions were held in an ion trap where their temperature was reduced to ?150 K, whereby the spectrum revealed two broad features at ?38,200 and ?45,700 cm(-1). Detailed calculations using density functional theory (DFT) show the complex can occupy three minimum energy structures with C2v and C2 (staggered and eclipsed) symmetries. Adiabatic time-dependent DFT (TDDFT) has been used to identify electronic transitions in [Cu(benzene)2](2+), and the calculations show these to fall into two groups that are in excellent agreement with the experimental data. However, the open-shell electronic configuration of Cu(2+) (d(9)) may give rise to excited states with double-excitation character, and the single-excitation adiabatic TDDFT treatment leads to extensive spin contamination. By quantifying the extent of spin contamination and allowing for the inclusion of a small percentage (?10%), the theory can provide quantitative agreement with the experimental data. PMID:25329443

Ma, Lifu; Koka, Joseph; Stace, Anthony J; Cox, Hazel

2014-11-13

254

Kinetic theory for a mobile impurity in a degenerate Tonks-Girardeau gas.  

PubMed

A kinetic theory describing the motion of an impurity particle in a degenerate Tonks-Girardeau gas is presented. The theory is based on the one-dimensional Boltzmann equation. An iterative procedure for solving this equation is proposed, leading to the exact solution in a number of special cases and to an approximate solution with the explicitly specified precision in a general case. Previously we reported that the impurity reaches a nonthermal steady state, characterized by an impurity momentum p(?) depending on its initial momentum p(0) [E. Burovski, V. Cheianov, O. Gamayun, and O. Lychkovskiy, Phys. Rev. A 89, 041601(R) (2014)]. In the present paper the detailed derivation of p(?)(p(0)) is provided. We also study the motion of an impurity under the action of a constant force F. It is demonstrated that if the impurity is heavier than the host particles, m(i)>m(h), damped oscillations of the impurity momentum develop, while in the opposite case, m(i)

Gamayun, O; Lychkovskiy, O; Cheianov, V

2014-09-01

255

RRKM Theory at the Gas-Surface Interface: Hydrogen Dissociation Dynamics on Cu(111)  

NASA Astrophysics Data System (ADS)

A simple picture of the hydrogen dissociation/associative desorption dynamics on Cu(111) emerges from a two-parameter, full dimensionality microcanonical unimolecular rate theory (MURT) model of the gas-surface reactivity. Vibrational frequencies for the reactive transition state were taken from 6D density functional theory calculations [Hammer, et al. Phys. Rev. Lett. 73, 1400 (1994)]. The MURT's parameters were fixed by simulation of experiment as: a H2 dissociation threshold energy of E0 = 79 kJ/mol and s = 1 surface atoms that actively exchange energy within the reactive transition state. Remarkably, MURT quantitatively predicts much of the dynamical behavior observed. The divergence of the statistical theoretical predictions from the experimental results at low rotational quantum numbers, J<=5, points towards the importance of dynamical steering at low J. The surface degrees of freedom are calculated to provide ˜30% of the energy required to surmount E0 under thermal equilibrium conditions. Explicit treatment of the surface (i.e., Ts>0 K) is a novel aspect of the MURT theoretical approach.

Abbott, Heather; Harrison, Ian

2006-03-01

256

A parametric study of vestibular stimulation during centrifugation  

E-print Network

Artificial Gravity (AG) provided by short-radius centrifugation is a promising countermeasure to the health problems associated with long duration human spaceflight. Head-turns performed during centrifugation, however, ...

Pouly, Jeremie M

2006-01-01

257

Vacuum chamber-free centrifuge with magnetic bearings  

NASA Astrophysics Data System (ADS)

Centrifuges are devices that separate particles of different densities and sizes through the application of a centrifugal force. If a centrifuge could be operated under atmospheric conditions, all vacuum-related components such as the vacuum chamber, vacuum pump, diffusion pump, and sealing could be removed from a conventional centrifuge system. The design and manufacturing procedure for centrifuges could then be greatly simplified to facilitate the production of lightweight centrifuge systems of smaller volume. Furthermore, the maintenance costs incurred owing to wear and tear due to conventional ball bearings would be eliminated. In this study, we describe a novel vacuum chamber-free centrifuge supported by magnetic bearings. We demonstrate the feasibility of the vacuum chamber-free centrifuge by presenting experimental results that verify its high-speed support capability and motoring power capacity.

Park, Cheol Hoon; Kim, Soohyun; Kim, Kyung-Soo

2013-09-01

258

Development of a body force model for centrifugal compressors  

E-print Network

This project is focused on modeling the internal ow in centrifugal compressors for the purpose of assessing the onset of rotating stall and surge. The current methods to determine centrifugal compressor stability limits ...

Kottapalli, Anjaney Pramod

2013-01-01

259

Astronaut Virgil Grissom preparing for centrifuge training  

NASA Technical Reports Server (NTRS)

Astronaut Virgil I. (Gus) Grissom, wearing the new Mercury pressure suit, is preparing for centrifuge training. He is receiving assistance in adjusting the breathing apparatus which is attached to a data recording device at his feet. Assisting him is Dr. Jackson.

1961-01-01

260

Family assessment: Centripetal and centrifugal family systems  

Microsoft Academic Search

A consideration of interactional style is useful to both researchers and clinicians interested in family assessment. This paper offers data and process evaluation scales designed to determine family interactional style, conceptualized as a continuum ranging from centripetal (CP) to centrifugal (CF), and containing at the midpoint a mixed area in which facets of both the CP and the CF styles

Martha Kelsey-smith; W. Robert Beavers M. D

1981-01-01

261

Porous media pressure distribution in centrifugal fields  

NASA Astrophysics Data System (ADS)

The simplest use of centrifuges to measure soil properties relies on steady state conditions. Analytical solutions, especially if they are simple, make interpretation of data more direct and transparent. Previous approximations are simplified and have a greatly improved accuracy. Using previous examples as a test, the error on pressure is always less than 1%, compared to about 10% with previous approximations.

Hogarth, W. L.; Stagnitti, F.; Barry, D. A.; Lockington, D. A.; Li, L.; Parlange, J.-Y.

2013-10-01

262

Centrifuge in space fluid flow visualization experiment  

NASA Technical Reports Server (NTRS)

A prototype flow visualization system is constructed to examine buoyancy driven flows during centrifugation in space. An axial density gradient is formed by imposing a thermal gradient between the two ends of the test cell. Numerical computations for this geometry showed that the Prandtl number plays a limited part in determining the flow.

Arnold, William A.; Wilcox, William R.; Regel, Liya L.; Dunbar, Bonnie J.

1993-01-01

263

Centrifugal Pump Experiment for Chemical Engineering Undergraduates  

ERIC Educational Resources Information Center

The purpose of this paper is to describe a Centrifugal Pump Experiment that provided an experiential learning experience to chemical engineering undergraduates at the University of Missouri in the spring of 2010 in the Unit Operations Laboratory course. Lab equipment was used by senior students with computer-based data and control technology. In…

Vanderslice, Nicholas; Oberto, Richard; Marrero, Thomas R.

2012-01-01

264

Conversion of centrifugal chillers to alternate refrigerants  

Microsoft Academic Search

The discovery of the adverse effect of certain chloroflourocarbon refrigerants on the upper atmosphere brought about the need to eliminate the offending refrigerants and replace them with those that are environmentally friendly. The use of a refrigerant different from that used in the original design of a centrifugal chiller creates issues of capacity, efficiency and reliability. The scope of the

G. E. Roark

1995-01-01

265

Research centrifuge accommodations on Space Station Freedom  

NASA Technical Reports Server (NTRS)

Life sciences research using plants and animals on the Space Station Freedom requires the ability to maintain live subjects in a safe and low stress environment for long durations at microgravity and at one g. The need for a centrifuge to achieve these accelerations is evident. Programmatic, technical, and cost considerations currently favor a 2.5 meter diameter centrifuge located either in the end cone of a Space Station Freedom node or in a separate module. A centrifuge facility could support a mix of rodent, plant, and small primate habitats. An automated cage extractor could be used to remove modular habitats in pairs without stopping the main rotor, minimizing the disruption to experiment protocols. The accommodation of such a centrifuge facility on the Space Station represents a significant demand on the crew time, power, data, volume, and logistics capability. It will contribute to a better understanding of the effects of space flight on humans, an understanding of plant growth in space for the eventual production of food, and an understanding of the role of gravity in biological processes.

Arno, Roger D.; Horkachuk, Michael J.

1990-01-01

266

Flow Pattern Characterization for a Centrifugal Impeller  

NASA Astrophysics Data System (ADS)

This paper proposes a model for characterizing the flow pattern of a centrifugal impeller attending to the severity of the reverse flow. The model assumes 1) a definition of an escaping particle as the one that flows in every operational point from the trailing edge towards the leading edge of the impeller blades, and 2) a characterization of flow where an operational point is said to have a theoretical flow pattern if it is not possible to establish a fully-reversed escaping particle on it. Therefore, the first part of the article is focused on defining an escaping particle for a centrifugal compressor. The model locates over the map of a centrifugal impeller the line that splits the map in two regions: the region on the right hand side, where a theoretical flow pattern can exist, and the region on the left, where a theoretical flow pattern cannot exist. Therefore, the locus of this line marks a frontier where the expected performance of the impeller cannot be sustained as high as expected. The second part of the article uses a high-performance commercial centrifugal impeller wheel for contrasting the model. A qualitative characterization of the surge line, conclusions and discussions are presented.

Benavides, Efrén M.

2014-08-01

267

Centrifugal governor for internal combustion engines  

Microsoft Academic Search

A centrifugal governor is described for use with an internal combustion engine, comprising: a control rack for regulating the quantity of fuel to be supplied to the engine; flyweights radially displaceable in response to the rotational speed of the engine; a tension lever pivotable about a stationary fulcrum in response to the radial displacement of the flyweights; a torque cam

Ohnishi

1986-01-01

268

Energy conservation techniques for centrifugal chillers  

Microsoft Academic Search

The sudden rise of the cost of energy forces the industry to re-evaluate its standards, design, and operational practices and long-range objectives so that the energy consumption of HVAC equipment does not place an unexpected financial burden on the owner. The main source of chilled water for large air conditioning systems is the centrifugal refrigeration machine and the engineer involved

Holbay

1976-01-01

269

Extracting hydrocarbons from water using a centrifuge  

NASA Astrophysics Data System (ADS)

An original method for the solid-phase microextraction of hydrocarbons from water using a centrifuge is proposed. Comparative results from the chromatographic elution of substances after liquid-phase and solid-phase microextraction are presented. The percentage of the extraction of substances from aqueous solutions and the minimum detection limit for aromatic and aliphatic compounds are calculated.

Ryabov, A. Yu.; Ilyina, A. A.; Chuikin, A. V.; Velikov, A. A.

2014-09-01

270

Thickener performance traced by multisample analytical centrifugation  

Microsoft Academic Search

Polymeric thickeners are important ingredients to adjust flow properties and stability of formulations. The effect of polymeric additives on dispersion properties is rather complex (viscosity of the continuous phase, adsorption and depletion effects, interaction with other ingredients). Therefore optimum formulation requires extensive experimental investigations.A new multisample approach is presented using analytical centrifugation (STEP-Technology), which allows for an accelerated characterisation of

T. Sobisch; D. Lerche

2008-01-01

271

Nonlinear Sensitive Control of Centrifugal Compressor  

Microsoft Academic Search

In this work, we treat the problems related to chemical and petrochemical plants of a certain complex process taking the centrifugal compressor as an example, a system being very complex by its physical structure as well as its behaviour (surge phenomenon). We propose to study the application possibilities of the recent control approaches to the compressor behaviour, and consequently evaluate

F. Laaouad; M. Bouguerra; A. Hafaifa; A. Iratni

2007-01-01

272

APPLICATIONS ANALYSIS REPORT: RETECH PLASMA CENTRIFUGAL FURNACE  

EPA Science Inventory

This document is an evaluation of the performance of the Retech Inc. Plasma Centrifugal Furnace (PCF) and its applicability as a treatment technique for soils contaminated with organic and/or inorganic compounds. oth the technical and economic aspects of the technology were exami...

273

APPLICATION ANALYSIS REPORT: RETECH PLASMA CENTRIFUGAL FURNACE  

EPA Science Inventory

This document is an evaluation of the performance of the Retech, Inc. Plasma Centrifugal Furnace (PCF) and its applicability as a treatment for soils contaminated with organic and/or inorganic compounds. Both the technical and economic aspectsof the technology were examined. A...

274

Theory and Calculation of the Condensation Growth of a Droplet in Pure Vapor and in a Vapor–Gas Mixture  

Microsoft Academic Search

Consideration is given to the theory of condensation as applied to the liquefaction of gases. Numerical calculations of the growth of a droplet using methane as an example revealed the decisive role of heat removal from its surface to the ambient medium in condensation from both a pure vapor and a vapor–gas mixture. It is shown that for very low

K. M. Aref'ev; Yu. G. Belostotskii; A. M. Koshelev

2001-01-01

275

TECHNICAL NOTE Centrifuge cone penetration tests in sand  

E-print Network

TECHNICAL NOTE Centrifuge cone penetration tests in sand M. D. BOLTON,Ã? M. W. GUI,Ã? J. GARNIER,{ J. F. CORTE,{ G. BAGGE,{ J. LAUE} and R. RENZIk KEYWORDS: centrifuge modelling; in-situ testing; laboratory tests; piles; sands. INTRODUCTION Centrifuges have been widely adopted in modelling geotechnical

Bolton, Malcolm

276

150 g-ton Capacity Centrifuge Renssealer Polytechnic Institute  

E-print Network

NEES@RPI 150 g-ton Capacity Centrifuge Renssealer Polytechnic Institute Department of Civil Institute (NEES@RPI) specializes in geotechnical engineering using the geotechnical centrifuge in 1989, the facility consists of : · A 150 g-ton geotechnical centrifuge · A one and two-dimensional in

Salama, Khaled

277

Centrifuge: Integrated Lease Management and Partitioning for Cloud Services  

E-print Network

Centrifuge: Integrated Lease Management and Partitioning for Cloud Services Atul Adya , John datacenter lease managers. This paper presents Centrifuge, a datacenter lease manager that solves this problem by integrating parti- tioning and lease management. Centrifuge consists of a set of libraries

Hunt, Galen

278

Drive torque actuation in active surge control of centrifugal compressors  

E-print Network

Drive torque actuation in active surge control of centrifugal compressors Jan Tommy Gravdahl , Olav to active surge control is presented for a centrifugal compressor driven by an electrical motor. The main speed Compressor performance control Figure 1: The compression system consists of a centrifugal

Gravdahl, Jan Tommy

279

Centrifugal Filter Devices for the Concentration and Purification of  

E-print Network

Centrifugal Filter Devices for the Concentration and Purification of Biological Samples � Amicon Ultra Ready for an evolution? ® #12;The next stage in centrifugal filter devices. The introduction of Amicon Ultra sets a new standard for centrifugal filter devices. This high performance ultrafiltration

Lebendiker, Mario

280

Testing of Expansive Clays in a Centrifuge Permeameter  

E-print Network

Testing of Expansive Clays in a Centrifuge Permeameter M. D. Plaisted & J. G. Zornberg with the objective of characterizing the swelling of highly plastic clays using a centrifuge permeameter. The new. This study, conducted using a comparatively simple, non- instrumented centrifuge device complements ongo- ing

Zornberg, Jorge G.

281

THE IMPACT OF UNCERTAIN CENTRIFUGE CAPILLARY PRESSURE ON RESERVOIR SIMULATION  

E-print Network

THE IMPACT OF UNCERTAIN CENTRIFUGE CAPILLARY PRESSURE ON RESERVOIR SIMULATION SAM SUBBEY, MIKE estimation of hydrocarbon reserves. The centrifuge procedure provides laboratory data, which can be inverted are uncertain. This paper shows how the uncertainty in centrifuge capillary pressure can be quantified. It also

Sambridge, Malcolm

282

Laminar flow effects in the coil planet centrifuge  

Microsoft Academic Search

The coil planet centrifuge designed by Ito employs flow of a single liquid phase, through a rotating coiled tube in a centrifugal force field, to provide a separation of particles based on sedimentation rates. Mathematical solutions are derived for the linear differential equations governing particle behavior in the coil planet centrifuge device. These solutions are then applied as the basis

F. T. Herrmann

1984-01-01

283

COMPARISON OF FATIGUE BEHAVIOR FOR CENTRIFUGALLY CAST AND  

E-print Network

COMPARISON OF FATIGUE BEHAVIOR FOR CENTRIFUGALLY CAST AND KEEL BLOCK CAST STEEL J.J. Gradman1 , R The objective of this research was to determine if location through the wall thickness of centrifugal castings affects fatigue properties and to compare fatigue and monotonic tensile properties of centrifugal castings

Beckermann, Christoph

284

Some Practical Aspects of Balancing an Ultra-Centrifuge Rotor  

Microsoft Academic Search

In this paper the method of balancing centrifuge rotors for initial three modes based on practical experience IS presented though, depending on the size of the centrifuge, more than one flexural modes have to be encountered. The object is to provide useful and practical information, as technical information on balancing of centrifuge rotors is hardly available because most of the

M. Zubair KHAN; M. SULEMAN; M. ASHRAF; A. Q. KHAN

1987-01-01

285

Review on stress corrosion and corrosion fatigue failure of centrifugal compressor impeller  

NASA Astrophysics Data System (ADS)

Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

Sun, Jiao; Chen, Songying; Qu, Yanpeng; Li, Jianfeng

2015-01-01

286

Analytical theory of mesoscopic Bose-Einstein condensation in an ideal gas  

NASA Astrophysics Data System (ADS)

We find the universal structure and scaling of the Bose-Einstein condensation (BEC) statistics and thermodynamics (Gibbs free energy, average energy, heat capacity) for a mesoscopic canonical-ensemble ideal gas in a trap with an arbitrary number of atoms, any volume, and any temperature, including the whole critical region. We identify a universal constraint-cutoff mechanism that makes BEC fluctuations strongly non-Gaussian and is responsible for all unusual critical phenomena of the BEC phase transition in the ideal gas. The main result is an analytical solution to the problem of critical phenomena. It is derived by, first, calculating analytically the universal probability distribution of the noncondensate occupation, or a Landau function, and then using it for the analytical calculation of the universal functions for the particular physical quantities via the exact formulas which express the constraint-cutoff mechanism. We find asymptotics of that analytical solution as well as its simple analytical approximations which describe the universal structure of the critical region in terms of the parabolic cylinder or confluent hypergeometric functions. The obtained results for the order parameter, all higher-order moments of BEC fluctuations, and thermodynamic quantities perfectly match the known asymptotics outside the critical region for both low and high temperature limits. We suggest two- and three-level trap models of BEC and find their exact solutions in terms of the cutoff negative binomial distribution (which tends to the cutoff gamma distribution in the continuous limit) and the confluent hypergeometric distribution, respectively. Also, we present an exactly solvable cutoff Gaussian model of BEC in a degenerate interacting gas. All these exact solutions confirm the universality and constraint-cutoff origin of the strongly non-Gaussian BEC statistics. We introduce a regular refinement scheme for the condensate statistics approximations on the basis of the infrared universality of higher-order cumulants and the method of superposition and show how to model BEC statistics in the actual traps. In particular, we find that the three-level trap model with matching the first four or five cumulants is enough to yield remarkably accurate results for all interesting quantities in the whole critical region. We derive an exact multinomial expansion for the noncondensate occupation probability distribution and find its high-temperature asymptotics (Poisson distribution) and corrections to it. Finally, we demonstrate that the critical exponents and a few known terms of the Taylor expansion of the universal functions, which were calculated previously from fitting the finite-size simulations within the phenomenological renormalization-group theory, can be easily obtained from the presented full analytical solutions for the mesoscopic BEC as certain approximations in the close vicinity of the critical point.

Kocharovsky, Vitaly V.; Kocharovsky, Vladimir V.

2010-03-01

287

Hydration of gas-phase ytterbium ion complexes studied by experiment and theory  

SciTech Connect

Hydration of ytterbium (III) halide/hydroxide ions produced by electrospray ionization was studied in a quadrupole ion trap mass spectrometer and by density functional theory (DFT). Gas-phase YbX{sub 2}{sup +} and YbX(OH){sup +} (X = OH, Cl, Br, or I) were found to coordinate from one to four water molecules, depending on the ion residence time in the trap. From the time dependence of the hydration steps, relative reaction rates were obtained. It was determined that the second hydration was faster than both the first and third hydrations, and the fourth hydration was the slowest; this ordering reflects a combination of insufficient degrees of freedom for cooling the hot monohydrate ion and decreasing binding energies with increasing hydration number. Hydration energetics and hydrate structures were computed using two approaches of DFT. The relativistic scalar ZORA approach was used with the PBE functional and all-electron TZ2P basis sets; the B3LYP functional was used with the Stuttgart relativistic small-core ANO/ECP basis sets. The parallel experimental and computational results illuminate fundamental aspects of hydration of f-element ion complexes. The experimental observations - kinetics and extent of hydration - are discussed in relationship to the computed structures and energetics of the hydrates. The absence of pentahydrates is in accord with the DFT results, which indicate that the lowest energy structures have the fifth water molecule in the second shell.

Rutkowski, Philip X; Michelini, Maria C.; Bray, Travis H.; Russo, Nino; Marcalo, Joaquim; Gibson, John K.

2011-02-11

288

Infrared spectra of dimethylquinolines in the gas phase: experiment and theory.  

PubMed

Infrared spectra of atmospherically important dimethylquinolines (DMQs), namely 2,4-DMQ, 2,6-DMQ, 2,7-DMQ, and 2,8-DMQ in the gas phase at 80 degrees C were recorded using a long variable path-length cell. DFT calculations were carried out to assign the bands in the experimentally observed spectra at the B3LYP/6-31G* level of theory. The spectral assignments particularly for the C-H stretching modes could not be made unambiguously using calculated anharmonic or scaled harmonic frequencies. To resolve this problem, a scaled force field method of assignment was used. Assignment of fundamental modes was confirmed by potential energy distributions (PEDs) of the normal modes derived by the scaled force fields using a modified version of the UMAT program in the QCPE package. We demonstrate that for large molecules such as the DMQs, the scaling of the force field is more effective in arriving at the correct assignment of the fundamentals for a quantitative vibrational analysis. An error analysis of the mean deviation of the calculated harmonic, anharmonic, and force field fitted frequencies from the observed frequency provides strong evidence for the correctness of the assignment. PMID:20701342

Das, Prasanta; Manogaran, S; Arunan, E; Das, Puspendu K

2010-08-19

289

Supernatant decanting on a centrifugal platform  

PubMed Central

This study presents a novel approach to decant supernatant on a centrifugal platform. By manipulating the centrifugally induced pressure and the elastic deformation of the plastic lids in the decanting chamber, fixed amounts of the supernatant can be decanted into the detection chamber at lower rotational speeds. The experimental results showed that decanted volume is affected by the volume of deformation and the operating parameters. Factors that influence the decanting ratio are also discussed. This approach has the advantages of simple design and low manufacturing cost; further, it has no need of surface modification. It has been applied to on-disk separation of plasma from whole blood, and the results showed good stability and repeatability. PMID:21522503

Shih, Chih-Hsin; Lu, Chien-Hsing; Yuan, Wei-Li; Chiang, Wei-Ling; Lin, Chia-Hui

2011-01-01

290

Continuous centrifuge decelerator for polar molecules.  

PubMed

Producing large samples of slow molecules from thermal-velocity ensembles is a formidable challenge. Here we employ a centrifugal force to produce a continuous molecular beam with a high flux at near-zero velocities. We demonstrate deceleration of three electrically guided molecular species, CH3F, CF3H, and CF3CCH, with input velocities of up to 200??m?s(-1) to obtain beams with velocities below 15??m?s(-1) and intensities of several 10(9)??mm(-2)?s(-1). The centrifuge decelerator is easy to operate and can, in principle, slow down any guidable particle. It has the potential to become a standard technique for continuous deceleration of molecules. PMID:24483892

Chervenkov, S; Wu, X; Bayerl, J; Rohlfes, A; Gantner, T; Zeppenfeld, M; Rempe, G

2014-01-10

291

Vibration analysis of large centrifugal pump rotors  

NASA Astrophysics Data System (ADS)

Through the critical speed of centrifugal pumps, internal flow field and the force of the impeller, we analyze centrifugal pump vibration. Using finite element analysis software ANSYS to calculate the natural frequency of the rotor system and the critical speed; with the help of the Fluent software to simulate pump internal flow field, we conclude that speed increase will not cause intense vibration of the fluid in the pump. Using unsteady numerical simulation we discovered that in an impeller suffering transient radial force cyclical change periodically, as well as the frequency size determined by the product of the impeller speed and number of blades, resonance phenomena should make impeller to transient radial force frequency. If wanting to avoid pump resonance when it is running away, the transient radial force frequency should avoid the frequency range which can cause resonance.

Y Zhao, W.; Ge, J. G.; Ma, D.; Li, C. M.; Bao, S. B.

2013-12-01

292

Spaceborne centrifugal relays for spacecraft propulsion  

NASA Technical Reports Server (NTRS)

Acceleration using centrifugal relays is a recently discovered method for the acceleration of spaceborne payloads to high velocity at high thrust. Centrifugal relays are moving rotors which progressively accelerate reaction mass to higher velocities. One important engineering problem consists of accurately tracking the position of the projectiles and rotors and guiding each projectile exactly onto the appropriate guide tracks on each rotor. The topics of this research are the system kinematics and dynamics and the computerized guidance system which will allow the projectile to approach each rotor with exact timing with respect to the rotor rotation period and with very small errors in lateral positions. Kinematics studies include analysis of rotor and projectile positions versus time and projectile/rotor interactions. Guidance studies include a detailed description of the tracking mechanism (interrupt of optical beams) and the aiming mechanism (electromagnetic focusing) including the design of electromagnetic deflection coils and the switching circuitry.

Ouzidane, Malika

1991-01-01

293

Centrifugal shot blasting. Innovative technology summary report  

SciTech Connect

At the US Department of Energy (DOE) Fernald Environmental Management Project (FEMP), the Facilities Closure and Demolition Projects Integrated Remedial Design/Remedial Action (RD/RA) work plan calls for the removal of one inch (1 in) depth of concrete surface in areas where contamination with technetium-99 has been identified. This report describes a comparative demonstration between two concrete removal technologies: an innovative system using Centrifugal Shot Blasting (CSB) and a modified baseline technology called a rotary drum planer.

Not Available

1999-07-01

294

Wave propagation through soils in centrifuge testing  

E-print Network

Wave propagation phenomena in soils can be experimentally simulated using centrifuge scale models. An original excitation device (drop-ball arrangement) is proposed to generate short wave trains. Wave reflections on model boundaries are taken into account and removed by homomorphic filtering. Propagation is investigated through dispersion laws. For drop-ball experiments, spherical wave field analysis assuming linear viscoelasticity leads to a complete analytical description of wave propagation. Damping phenomena are examined and evaluated using this description.

Semblat, J F; 10.1142/S1363246998000071

2009-01-01

295

Operating and maintenance guidelines for screenbowl centrifuges  

SciTech Connect

Plant dewatering circuits equipped with screenbowl centrifuges need to be well designed, properly operated, and adequately maintained to maximize the dewatering performance. The most important 'feed variables' are particle size, dry solids feed rate and slurry flow rate. The most important 'machine variables' include pool depth, rotational speed and gearbox ratio. The article discusses the effect of these parameters and offers some maintenance guidelines. The article was adapted from a paper presented at CoalPrep 2008. 6 refs., 2 figs., 2 tabs.

Jahnig, W.S.R.; Bratton, R.; Luttrell, G. [Decanter Machine, Johnson City, TN (United States)

2009-01-15

296

CAVITATION CFD IN A CENTRIFUGAL PUMP  

Microsoft Academic Search

The cavitation flow in a low specific centrifugal pump is analyzed by using two types of cavitation CFD codes. A locally homogeneous model of compressible air-vapor-liquid two-phase medium is applied to calculate the objective flow. Constant Enthalpy Vaporization model is also applied. Numerical results are compared to measured results. At the cavitation breakdown of the BEP flow rate, the throat

Motohiko Nohmi; Akira Goto; Yuka Iga; Toshiaki Ikohagi

297

Axial inlet conversion to a centrifugal compressor with magnetic bearings  

SciTech Connect

NOVA's Alberta Gas Transmission Division transports natural gas via pipeline throughout the province of Alberta, Canada, exporting it to eastern Canada, US, and British Columbia. There is a continuing effort to operate the facilities and pipeline at the highest possible efficiency. One area being addressed to improve efficiency is compression of the gas. By improving compressor efficiency, fuel consumption and hence operating costs can be reduced. One method of improving compressor efficiency is by converting the compressor to an axial inlet configuration, a conversion that has been carried out more frequently in the past years. Concurrently, conventional hydrodynamic bearings have been replaced with magnetic bearings on many centrifugal compressors. This paper discusses the design and installation for converting a radial overhung unit to an axial inlet configuration, having both magnetic bearings and a thrust reducer. The thrust reducer is required to reduce axial compressor shaft loads, to a level that allows the practical installation of magnetic bearings within the space limitations of the compressor (Bear and Gibson, 1992).

Novecosky, T. (NOVA Corp., Edmonton, Alberta (Canada))

1994-01-01

298

In-vivo Centrifugation of Drosophila Embryos  

PubMed Central

A major strategy for purifying and isolating different types of intracellular organelles is to separate them from each other based on differences in buoyant density. However, when cells are disrupted prior to centrifugation, proteins and organelles in this non-native environment often inappropriately stick to each other. Here we describe a method to separate organelles by density in intact, living Drosophila embryos. Early embryos before cellularization are harvested from population cages, and their outer egg shells are removed by treatment with 50% bleach. Embryos are then transferred to a small agar plate and inserted, posterior end first, into small vertical holes in the agar. The plates containing embedded embryos are centrifuged for 30 min at 3000g. The agar supports the embryos and keeps them in a defined orientation. Afterwards, the embryos are dug out of the agar with a blunt needle. Centrifugation separates major organelles into distinct layers, a stratification easily visible by bright-field microscopy. A number of fluorescent markers are available to confirm successful stratification in living embryos. Proteins associated with certain organelles will be enriched in a particular layer, demonstrating colocalization. Individual layers can be recovered for biochemical analysis or transplantation into donor eggs. This technique is applicable for organelle separation in other large cells, including the eggs and oocytes of diverse species. PMID:20613707

Tran, Susan L.; Welte, Michael A.

2010-01-01

299

Shallow water model for horizontal centrifugal casting  

NASA Astrophysics Data System (ADS)

A numerical model was proposed to simulate the solidification process of an outer shell of work roll made by the horizontal centrifugal casting technique. Shallow water model was adopted to solve the 2D average flow dynamics of melt spreading and the average temperature distribution inside the centrifugal casting mould by considering the centrifugal force, Coriolis force, viscous force due to zero velocity on the mould wall, gravity, and energy transport by the flow. Additionally, a 1D sub-model was implemented to consider the heat transfer in the radial direction from the solidifying shell to the mould. The solidification front was tracked by fulfilling the Stefan condition. Radiative and convective heat losses were included from both, the free liquid surface and the outer wall of the mould. Several cases were simulated with the following assumed initial conditions: constant height of the liquid metal (10, 20, and 30 mm), uniform temperature of the free liquid surface (1755 K). The simulation results have shown that while the solidification front remained rather flat, the free surface was disturbed by waves. The amplitude of waves increased with the liquid height. Free surface waves diminished as the solidification proceeded.

Bohá?ek, J.; Kharicha, A.; Ludwig, A.; Wu, M.

2012-07-01

300

Research opportunities with the Centrifuge Facility  

NASA Technical Reports Server (NTRS)

The Centrifuge Facility on Space Station Freedom will consist of a 2.5-meter diameter Centrifuge accommodating two concentric rings of habitats and providing variable g-forces between 0.01 g and 2.0 g; modular habitats providing housing and lifesupport for rats, mice, and plants; a habitat holding system providing power, water, airflow and other utilities to several modular habitats; and a life sciences glovebox, an isolated work volume accommodating simultaneous operations by at least two scientists and providing lighting, airflow, video and data access, and other experiment support functions. The centrifuge facility will enable long-duration animal and plant microgravity research not previously possible in the NASA flight research program. It will offer unprecedented opportunities for use of on-board 1-g control populations and statistically significant numbers of specimens. On orbit 1-g controls will allow separation of the effects of microgravity from other environmental factors. Its selectable-g and simultaneous multiple-g capabilities will enable studies of gravitational thresholds, the use of artificial gravity as a countermeasure to the effects of microgravity, and ready simulation of Lunar and Martian gravities.

Funk, Glenn A.

1992-01-01

301

Stable isotope enrichment using a plasma centrifuge  

NASA Astrophysics Data System (ADS)

A primary goal of the Department of Energy's Isotope Development and Production for Research and Applications Program (Isotope Program) within the Office of Nuclear Physics (NP) is to produce isotopes that are in short supply in the U.S. and of which there exists no or insufficient domestic commercial production capability. A vacuum arc plasma centrifuge is a rigid rotor column of metal plasma in which centrifugal forces re-distribute ions radially according to their mass/charge ratio. Early work demonstrated rotation at 2 million rpm and separation of various stable isotopes. The spinning plasma column had a Gaussian flux profile, peaked on the rigid rotor axis. This work adopts a more efficient approach, with the plasma created as a hollow column, wherein the flux is concentrated at larger radii where the centrifugal action is highest. By tailoring the vacuum arc discharge geometry, the rotation rate can also be increased to ˜10 million rpm. Data from Cu, Al and other metal plasmas will be presented and discussed in light of enriched stable isotopes needed for research and medicine.

Krishnan, Mahadevan; Bures, Brian; Madden, Robert

2012-10-01

302

Numerical study of a swirled turbulent flow in the separation zone of a centrifugal air separator  

Microsoft Academic Search

A mathematical model of a swirled turbulent flow in the separation zone of a pneumatic centrifugal device is presented. The\\u000a model is based on the known k-? model of turbulence proposed by Wilcox. The influence of rotation of the separation-zone walls,\\u000a input swirl of the gas flow, and other characteristic parameters on the mean velocity field is demonstrated. A comparison

A. V. Shvab; P. N. Zyatikov; Sh. R. Sadretdinov; A. G. Chepel’

2010-01-01

303

Why the Langevin-Debye theory of molecular polarisation fails in gas phase  

Microsoft Academic Search

The classical polarization formula of Langevin, which holds in the solid\\/liquid state, does not satisfy many experimental facts in gas phase, especially in diluted gas mixtures. The new formulation of the molecular polarization in gas phase is obtained on phenomenological grounds analysing the motion that polar molecules undergo under an electric field. It is shown that the polarization amplitude in

M. Michelini

304

Adsorption of SF6 decomposed gas on anatase (101) and (001) surfaces with oxygen defect: A density functional theory study  

PubMed Central

The detection of partial discharge by analyzing the components of SF6 gas in gas-insulated switchgears is important to the diagnosis and assessment of the operational state of power equipment. A gas sensor based on anatase TiO2 is used to detect decomposed gases in SF6. In this paper, first-principle density functional theory calculations are adopted to analyze the adsorption of SO2, SOF2, and SO2F2, the primary decomposition by-products of SF6 under partial discharge, on anatase (101) and (001) surfaces. Simulation results show that the perfect anatase (001) surface has a stronger interaction with the three gases than that of anatase (101), and both surfaces are more sensitive and selective to SO2 than to SOF2 and SO2F2. The selection of a defect surface to SO2, SOF2, and SO2F2 differs from that of a perfect surface. This theoretical result is corroborated by the sensing experiment using a TiO2 nanotube array (TNTA) gas sensor. The calculated values are analyzed to explain the results of the Pt-doped TNTA gas sensor sensing experiment. The results imply that the deposited Pt nanoparticles on the surface increase the active sites of the surface and the gas molecules may decompose upon adsorption on the active sites. PMID:24755845

Zhang, Xiaoxing; Chen, Qinchuan; Tang, Ju; Hu, Weihua; Zhang, Jinbin

2014-01-01

305

A systematic study of rare gas atoms encapsulated in small fullerenes using dispersion corrected density functional theory.  

PubMed

The most stable fullerene structures from C20 to C60 are chosen to study the energetics and geometrical consequences of encapsulating the rare gas elements He, Ne, or Ar inside the fullerene cage using dispersion corrected density functional theory. An exponential increase in stability is found with increasing number of carbon atoms. A similar exponential law is found for the volume expansion of the cage due to rare gas encapsulation with decreasing number of carbon atoms. We show that dispersion interactions become important with increasing size of the fullerene cage, where Van der Waals forces between the rare gas atom and the fullerene cage start to dominate over repulsive interactions. The smallest fullerenes where encapsulation of a rare gas element is energetically still favorable are He@C48 , Ne@C52 , and Ar@C58 . While dispersion interactions follow the trend Ar?>?Ne?>?He inside C60 due to the trend in the rare gas dipole polarizabilities, repulsive forces become soon dominant with smaller cage size and we have a complete reversal for the energetics of rare gas encapsulation at C50 . © 2014 Wiley Periodicals, Inc. PMID:25503487

Sure, Rebecca; Tonner, Ralf; Schwerdtfeger, Peter

2015-01-15

306

Partition functions of superconformal Chern-Simons theories from Fermi gas approach  

NASA Astrophysics Data System (ADS)

We study the partition function of three-dimensional superconformal Chern-Simons theories of the circular quiver type, which are natural generalizations of the ABJM theory, the worldvolume theory of M2-branes. In the ABJM case, it was known that the perturbative part of the partition function sums up to the Airy function as Z( N) = e A C -1/3Ai[ C -1/3( N - B)] with coefficients C, B and A and that for the non-perturbative part the divergences coming from the coefficients of worldsheet instantons and membrane instantons cancel among themselves. We find that many of the interesting properties in the ABJM theory are extended to the general superconformal Chern-Simons theories. Especially, we find an explicit expression of B for general theories, a conjectural form of A for a special class of theories, and cancellation in the non-perturbative coefficients for the simplest theory next to the ABJM theory.

Moriyama, Sanefumi; Nosaka, Tomoki

2014-11-01

307

Theory versus experiment for the rotordynamic coefficients of annular gas seals. Part 2: Constant clearance and convergent-tapered geometry  

NASA Technical Reports Server (NTRS)

The leakage and rotordynamic coefficients of constant-clearance and convergent-tapered annular gas seals were measured in an experimental test facility. The results are presented along with the theoretically predicted values. Of particular interest is the prediction that optimally tapered seals have significantly larger direct siffness than straight seals. The experimental results verify this prediction. Generally the theory does quite well, but fails to predict the large increase in direct stiffness when the fluid is pre-rotated.

Nelson, C. C.; Childs, D. W.; Nicks, C.; Elrod, D.

1985-01-01

308

Hydraulic design and performance analysis of low specific speed centrifugal pump  

NASA Astrophysics Data System (ADS)

Since low specific speed centrifugal pump with long narrow flow divergent channels has positive slope of head-capacity characteristic curve, low flow rate instability and high flow rate power overload, special events about its hydraulic design are still under study. This paper demonstrates a method for hydraulic design of low specific speed centrifugal pump complex impeller (with splitter blades) which is based on 2D flow theory. In this method, obtain the basic geometry parameters by empirical correlation, adjust impeller profile according to given flow cross section area distribution and wrapping angles distribution, relate the position of splitter blades to slip factor. Based on this method, low specific speed centrifugal pump impellers have been designed using the same design parameters (Head, Capacity, Rotation Speed, etc) with different factors. And 3D turbulent flow fields in design pumps have been solved by using RANS equations with RNG k-epsilon turbulence model. The investigation to the effects of different splitter blades on velocity distributions and pressure distributions along the flow channels and hydraulic performance of centrifugal pumps are presented. The result shows that properly placed splitter blades by choosing suitable design factors will improve the flow in the pump and enhance the hydraulic performance of it.

Zhou, X.; Zhang, Y. X.; Ji, Z. L.; Chen, L.

2012-11-01

309

Metal/gas MHD conversion  

NASA Astrophysics Data System (ADS)

Operation features, theory, performance, and possible spatial applications of metal/gas MHD electrical generators are described. The working principle comprises an MHD channel, surrounded by a magnet, filled with a molten, highly conductive metal into which gas is pumped. The heat of the metal expands the gas, forcing a flow through the magnetic field crossing the channel, thus creating an electrical current conducted by the metal. The gas and metal are separated by a centrifugal device and both are redirected into the channel, forming thereby a double closed circuit when the heat of the molten metal is returned to the flow. Necessary characteristics for the gas such as a fairly low vaporization temperature and nonmiscibility with the metal, are outlined, and a space system using Li-Cs or Z-K as the heat carrier kept molten by a parabolic dish system is sketched. Equations governing the fluid mechanics, thermodynamics, and the electrical generation are defined. The construction of a prototype MHD generator using a tin-water flow operating at 250 C, a temperature suitable for coupling to solar heat sources, is outlined, noting expected efficiencies of 20-30 percent.

Thibault, J. P.; Joussellin, F.; Alemany, A.; Dupas, A.

1982-09-01

310

Behavior of capillary valves in centrifugal microfluidic devices prepared by three-dimensional printing  

Microsoft Academic Search

This paper details the behavior of capillary valves in centrifugal microfluidic devices prepared by three-dimensional (3D),\\u000a or solid-object, printing. Microfluidic structures containing valve channels with different widths, heights, and radial distances\\u000a from the center of rotation were studied and compared with extant capillary valve theories. Due to the printing process, the\\u000a produced valve channels possessed a ridged or “scalloped” pattern.

Jessica L. Moore; Austin McCuiston; Isaac Mittendorf; Rudy Ottway; R. Daniel Johnson

2011-01-01

311

Confinement of Plasma along Shaped Open Magnetic Fields from the Centrifugal Force of Supersonic Plasma Rotation  

SciTech Connect

Interferometric density measurements in plasmas rotating in shaped, open magnetic fields demonstrate strong confinement of plasma parallel to the magnetic field, with density drops of more than a factor of 10. Taken together with spectroscopic measurements of supersonic ExB rotation of sonic Mach 2, these measurements are in agreement with ideal MHD theory which predicts large parallel pressure drops balanced by centrifugal forces in supersonically rotating plasmas.

Teodorescu, C.; Young, W. C.; Swan, G. W. S.; Ellis, R. F.; Hassam, A. B.; Romero-Talamas, C. A. [University of Maryland, College Park, Maryland 20742 (United States)

2010-08-20

312

A High Reliability Gas-driven Helium Cryogenic Centrifugal Compressor  

Microsoft Academic Search

A helium cryogenic compressor was developed and tested in real conditions in 1996. The achieved objective was to compress 0.018 kg\\/s Helium at 4 K @ 1000 Pa (10 mbar) up to 3000 Pa (30 mbar). This project was an opportunity to develop and test an interesting new concept in view of future needs. The main features of this new

M Bonneton; L Tavian; Guy M Gistau-Baguer; F Turcat; P Viennot

1998-01-01

313

Laminar flow effects in the coil planet centrifuge  

NASA Technical Reports Server (NTRS)

The coil planet centrifuge designed by Ito employs flow of a single liquid phase, through a rotating coiled tube in a centrifugal force field, to provide a separation of particles based on sedimentation rates. Mathematical solutions are derived for the linear differential equations governing particle behavior in the coil planet centrifuge device. These solutions are then applied as the basis of a model for optimizing particle separations.

Herrmann, F. T.

1984-01-01

314

LES MOLCULES DANS UN CHAMP CENTRIFUGE INTENSE; par T. SVEDBERG.  

E-print Network

LES MOL�CULES DANS UN CHAMP CENTRIFUGE INTENSE; par T. SVEDBERG. Université d'Upsala (Suède). Sommaire. 2014 De l'étude du comportement des molécules dans des champs centrifuges intenses on peut tirer exposée. L'auteur décrit la réalisation des champs centrifuges allant jusqu'à 200 000 fois la pesanteur

Paris-Sud XI, Université de

315

Laminar flow effects in the coil planet centrifuge  

NASA Astrophysics Data System (ADS)

The coil planet centrifuge designed by Ito employs flow of a single liquid phase, through a rotating coiled tube in a centrifugal force field, to provide a separation of particles based on sedimentation rates. Mathematical solutions are derived for the linear differential equations governing particle behavior in the coil planet centrifuge device. These solutions are then applied as the basis of a model for optimizing particle separations.

Herrmann, F. T.

316

Subjective stress factors in centrifuge training for military aircrews  

Microsoft Academic Search

This study investigates stress-influence factors perceived by military aircrews undergoing centrifuge training, which lowers the incidence of G-induced loss of consciousness (G-LOC) for the crews of high-performance combat aircrafts. We used questionnaires to assess the subjective stress-influence factors of crews undergoing centrifuge training. Professionals in aviation physiology identified attributes measuring the perceived stress induced by centrifuge training, which were segmented

Pei-Chun Lin; Jenhung Wang; Shih-Chin Li

317

Rotational spectroscopy with an optical centrifuge.  

PubMed

We demonstrate a new spectroscopic method for studying electronic transitions in molecules with extremely broad range of angular momentum. We employ an optical centrifuge to create narrow rotational wave packets in the ground electronic state of (16)O2. Using the technique of resonance-enhanced multi-photon ionization, we record the spectrum of multiple ro-vibrational transitions between X(3)?g(-) and C(3)?g electronic manifolds of oxygen. Direct control of rotational excitation, extending to rotational quantum numbers as high as N ? 120, enables us to interpret the complex structure of rotational spectra of C(3)?g beyond thermally accessible levels. PMID:24448425

Korobenko, Aleksey; Milner, Alexander A; Hepburn, John W; Milner, Valery

2014-03-01

318

Improving the efficiency of centrifugal fans  

E-print Network

the Inlet 4. 4 (b) 4. 4 (c) 4 . 5(a) 4. 5(b) 4 ' 5(c) 4. 5(d) 4. 6(a) 4. 6(b) Bellmouth And the Blade Ends Inlet Rings Installed Inlet Ring Modification Fan With Airfoil Blading Installed Airfoil Blading Modification A Comparison... in this study. See Figure 1. 4. A very important are in the design of a centrifu- gal fan is the inlet area. Nearly all centrifugal fans employ the bellmouth type shape of inlet. This shape allows for a smooth reduction in area which gives rise to a minimum...

Wolfe, Clifford Kent

2012-06-07

319

Effects of centrifugation on gonadal and adrenocortical steroids in rats  

NASA Technical Reports Server (NTRS)

Many endocrine systems are sensitive to external changes in the environment. Both the pituitary adrenal and pituitary gonadal systems are affected by stress including centrifugation stress. The effect of centrifugation on the pituitary gonadal and pituitary adrenocortical systems was examined by measuring the gonadal and adrenal steroids in the plasma and brain following different duration and intensity of centrifugation stress in rats. Two studies were completed and the results are presented. The second study was carried out to describe the developmental changes of brain, plasma and testicular testosterone and dihydrotestosterone in Sprague Dawley rats so that the effect of centrifugation stress on the pituitary gonadal syatem could be better evaluated in future studies.

Kakihana, R.; Butte, J. C.

1980-01-01

320

Incremental adaptation to yaw head movements during 30 RPM centrifugation  

E-print Network

Artificial Gravity (AG) provided by short-radius centrifugation is a promising countermeasure against the harmful physiological effects of prolonged weightlessness. However, the vestibular stimulus associated with making ...

Elias, Paul Z. (Paul Ziad)

2006-01-01

321

Get your vertical basket centrifuges off to a good start  

SciTech Connect

For solid-liquid separation, vertical-basket centrifuges are established workhorses in many of the chemical process industries. Despite this widespread familiarity, care must always be taken when specifying these centrifuges and starting them up. First, the author points out a wide range of features, options and product measures that should be kept in mind while preparing the specification for a vertical-basket centrifuge. Then, he describes good practices for the process design associated with the centrifuge. Finally, he offers a number of guidelines for trouble-free startup.

Jarosz, P.H. [Dow Chemical Co., Midland, MI (United States)

1997-06-01

322

Numerical analysis of flow in ultra micro centrifugal compressor -influence of meridional configuration  

NASA Astrophysics Data System (ADS)

A single stage ultra micro centrifugal compressor constituting ultra micro gas turbine is required to operate at high rotational speed in order to achieve the pressure ratio which establishes the gas turbine cycle. As a consequence, the aerodynamic losses can be increased by the interaction of a shock wave with the boundary layer on the blade surface. Moreover, the centrifugal force which exceeds the allowable stress of the impeller material can act on the root of blades. On the other hand, the restrictions of processing technology for the downsizing of impeller not only relatively enlarge the size of tip clearance but also make it difficult to shape the impeller with the three-dimensional blade. Therefore, it is important to establish the design technology for the impeller with the two-dimensional blade which possesses the sufficient aerodynamic performance and enough strength to bear the centrifugal force caused by the high rotational speed. In this study, the flow in two types of impeller with the two-dimensional blade which have different meridional configuration was analyzed numerically. The computed results clarified the influence of the meridional configuration on the loss generations in the impeller passage.

Kaneko, Masanao; Tsujita, Hoshio; Hirano, Toshiyuki

2013-04-01

323

Centrifugally Stimulated Exospheric Ion Escape at Mercury  

NASA Technical Reports Server (NTRS)

We investigate the transport of ions in the low-altitude magnetosphere magnetosphere of Mercury. We show that, because of small spatial scales, the centrifugal effect due to curvature of the E B drift paths can lead to significant particle energization in the parallel direction. We demonstrate that because of this effect, ions with initial speed smaller than the escape speed such as those produced via thermal desorption can overcome gravity and escape into the magnetosphere. The escape route of this low-energy exosphere originating material is largely controlled by the magnetospheric convection rate. This escape route spreads over a narrower range of altitudes when the convection rate increases. Bulk transport of low-energy planetary material thus occurs within a limited region of space once moderate magnetospheric convection is established. These results suggest that, via release of material otherwise gravitationally trapped, the E B related centrifugal acceleration is an important mechanism for the net supply of plasma to the magnetosphere of Mercury.

Delcourt, Dominique; Seki, K.; Terada, N.; Moore, Thomas E.

2012-01-01

324

Experimental Investigation of Centrifugal Compressor Stabilization Techniques  

NASA Technical Reports Server (NTRS)

Results from a series of experiments to investigate techniques for extending the stable flow range of a centrifugal compressor are reported. The research was conducted in a high-speed centrifugal compressor at the NASA Glenn Research Center. The stabilizing effect of steadily flowing air-streams injected into the vaneless region of a vane-island diffuser through the shroud surface is described. Parametric variations of injection angle, injection flow rate, number of injectors, injector spacing, and injection versus bleed were investigated for a range of impeller speeds and tip clearances. Both the compressor discharge and an external source were used for the injection air supply. The stabilizing effect of flow obstructions created by tubes that were inserted into the diffuser vaneless space through the shroud was also investigated. Tube immersion into the vaneless space was varied in the flow obstruction experiments. Results from testing done at impeller design speed and tip clearance are presented. Surge margin improved by 1.7 points using injection air that was supplied from within the compressor. Externally supplied injection air was used to return the compressor to stable operation after being throttled into surge. The tubes, which were capped to prevent mass flux, provided 9.3 points of additional surge margin over the baseline surge margin of 11.7 points.

Skoch, Gary J.

2003-01-01

325

Wave Augmented Diffusers for Centrifugal Compressors  

NASA Technical Reports Server (NTRS)

A conceptual device is introduced which would utilize unsteady wave motion to slow and turn flows in the diffuser section of a centrifugal compressor. The envisioned device would substantially reduce the size of conventional centrifugal diffusers by eliminating the relatively large ninety degree bend needed to turn the flow from the radial/tangential to the axial direction. The bend would be replaced by a wall and the flow would instead exit through a series of rotating ports located on a disk, adjacent to the diffuser hub, and fixed to the impeller shaft. The ports would generate both expansion and compression waves which would rapidly transition from the hub/shroud (axial) direction to the radial/tangential direction. The waves would in turn induce radial/tangential and axial flow. This paper presents a detailed description of the device. Simplified cycle analysis and performance results are presented which were obtained using a time accurate, quasi-one-dimensional CFD code with models for turning, port flow conditions, and losses due to wall shear stress. The results indicate that a periodic wave system can be established which yields diffuser performance comparable to a conventional diffuser. Discussion concerning feasibility, accuracy, and integration follow.

Paxson, Daniel E.; Skoch, Gary J.

1998-01-01

326

Centrifugal force induced by relativistically rotating spheroids and cylinders  

E-print Network

Starting from the gravitational potential of a Newtonian spheroidal shell we discuss electrically charged rotating prolate spheroidal shells in the Maxwell theory. In particular we consider two confocal charged shells which rotate oppositely in such a way that there is no magnetic field outside the outer shell. In the Einstein theory we solve the Ernst equations in the region where the long prolate spheroids are almost cylindrical; in equatorial regions the exact Lewis "rotating cylindrical" solution is so derived by a limiting procedure from a spatially bound system. In the second part we analyze two cylindrical shells rotating in opposite directions in such a way that the static Levi-Civita metric is produced outside and no angular momentum flux escapes to infinity. The rotation of the local inertial frames in flat space inside the inner cylinder is thus exhibited without any approximation or interpretational difficulties within this model. A test particle within the inner cylinder kept at rest with respect to axes that do not rotate as seen from infinity experiences a centrifugal force. Although the spacetime there is Minkowskian out to the inner cylinder nevertheless that space has been induced to rotate, so relative to the local inertial frame the particle is traversing a circular orbit.

Joseph Katz; Donald Lynden-Bell; Jiri Bicak

2011-02-25

327

Chemical oxygen-iodine laser with a centrifugal spray generator of singlet oxygen  

NASA Astrophysics Data System (ADS)

A chemical oxygen-iodine laser driven by the centrifugal spray generator of singlet oxygen was developed and experimentally studied. Modeling and experimental studies showed that the designed generator can produce singlet oxygen, O2(1?g), with a high efficiency (chlorine utilization 0.68 - 0.87 and O2(1?g) yield 0.35 - 0.7) even at very high generator pressures (25 - 70 kPa), which cannot be attained by other O2(1?g) generators. This high-pressure operation should be beneficial for a pressure recovery system of the laser. Another specific feature of the generator is a very high BHP utilization (0.24-0.6). The developed separator can effectively remove even small droplets (> 1 ?m) from gas at the generator exit. Preliminary experiments on the COIL driven the centrifugal spray generator provided the small signal gain up to 0.5 % cm-1.

Špalek, Otomar; Jirásek, Vít; ?enský, Miroslav; Kodymová, Jarmila

2010-09-01

328

Finite-density corrections to the unitary Fermi gas: A lattice perspective from dynamical mean-field theory  

SciTech Connect

We investigate the approach to the universal regime of the dilute unitary Fermi gas as the density is reduced to zero in a lattice model. To this end we study the chemical potential, superfluid order parameter and internal energy of the attractive Hubbard model in three different lattices with densities of states (DOSs) which share the same low-energy behavior of fermions in three-dimensional free space: a cubic lattice, a 'Bethe lattice' with a semicircular DOS, and a 'lattice gas' with parabolic dispersion and a sharp energy cutoff that ensures the normalization of the DOS. The model is solved using dynamical mean-field theory, that treats directly the thermodynamic limit and arbitrarily low densities, eliminating finite-size effects. At densities on the order of one fermion per site the lattice and its specific form dominate the results. The evolution to the low-density limit is smooth and it does not allow to define an unambiguous low-density regime. Such finite-density effects are significantly reduced using the lattice gas, and they are maximal for the three-dimensional cubic lattice. Even though dynamical mean-field theory is bound to reduce to the more standard static mean field in the limit of zero density due to the local nature of the self-energy and of the vertex functions, it compares well with accurate Monte Carlo simulations down to the lowest densities accessible to the latter.

Privitera, Antonio [CRS SMC, CNR-INFM and Dipartimento di Fisica, Universita di Roma 'La Sapienza', Piazzale Aldo Moro 2, I-00185 Roma (Italy); Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, 60438 Frankfurt am Main (Germany); Capone, Massimo [CRS SMC, CNR-INFM and Dipartimento di Fisica, Universita di Roma 'La Sapienza', Piazzale Aldo Moro 2, I-00185 Roma (Italy); ISC-CNR, Via dei Taurini 19, I-00185 Roma (Italy); Castellani, Claudio [CRS SMC, CNR-INFM and Dipartimento di Fisica, Universita di Roma 'La Sapienza', Piazzale Aldo Moro 2, I-00185 Roma (Italy)

2010-01-01

329

Solar wind flow about the terrestrial planets. II - Comparison with gas dynamic theory and implications for solar-planetary interactions  

NASA Technical Reports Server (NTRS)

Bow shock models are employed to determine and compare the solar wind flows about Venus, Mars, and the earth. Initially, gas dynamic theory predictions are compared with the large data base available for the near-earth environment. The observed shape and location of the magnetopause proved sufficient for predicting the average dayside bow shock position to within 2% error. Use of the same gas dynamics theory produced highly disparate results for the flows past Venus and Mars. A variation of 510-1000 km altitude (high) for the solar wind-obstacle interface was found for Mars, thus requiring the presence of an effective magnetic moment of within 0.6 of 1.4 x 10 to the 22nd G/cu cm in the Martian magnetosphere, consistent with Viking data. The Venus bow wave was calculated to be closer to the planet than possible with a purely ionospheric interaction, indicating that solar wind-neutral atmosphere interactions in the lower ionosheath must necessarily be included in a gas dynamic modeling of the Venus obstacle to the solar wind.

Slavin, J. A.; Holzer, R. E.; Spreiter, J. R.; Stahara, S. S.; Chaussee, D. S.

1983-01-01

330

Partition Functions of Superconformal Chern-Simons Theories from Fermi Gas Approach  

E-print Network

We study the partition function of three-dimensional ${\\mathcal N}=4$ superconformal Chern-Simons theories of the circular quiver type, which are natural generalizations of the ABJM theory, the worldvolume theory of M2-branes. In the ABJM case, it was known that the perturbative part of the partition function sums up to the Airy function as $Z(N)=e^{A}C^{-1/3}\\mathrm{Ai}[C^{-1/3}(N-B)]$ with coefficients $C$, $B$ and $A$ and that for the non-perturbative part the divergences coming from the coefficients of worldsheet instantons and membrane instantons cancel among themselves. We find that many of the interesting properties in the ABJM theory are extended to the general superconformal Chern-Simons theories. Especially, we find an explicit expression of $B$ for general ${\\mathcal N}=4$ theories, a conjectural form of $A$ for a special class of theories, and cancellation in the non-perturbative coefficients for the simplest theory next to the ABJM theory.

Sanefumi Moriyama; Tomoki Nosaka

2014-07-16

331

Experimental studies on the optimization design of a low specific speed centrifugal pump  

NASA Astrophysics Data System (ADS)

Start your abstract here... For a low specific speed centrifugal pump with the requirement of high efficiency of 68% and non-overload power characteristics, series experimental studies, by matching 9 volutes with 19 impellers were done. By combining the former research results about the splitters and the non-overload theory in centrifugal pump, the theoretical conditions to achieve the property of non-overload in a centrifugal pump with splitters was analyzed, and formulas to estimate the maximum shaft power and its position are derived. Based on the requirement of high efficiency and non-overload, blade outlet angle ?2, blade outlet width b2, volute throat area Ft and the inlet diameter of splitters Di were chosen with three levels to design a normal L9 (34) orthogonal test scheme. Meanwhile, the optimized design scheme was determined, and corresponding test was done also, it demonstrates that the experiment purpose was reached, the design method to combine the splitters and non-overload theory is reasonable, which can get the property of high efficiency and non-overload.

Zhang, J. F.; Yuan, Y.; Yuan, S. Q.; Lu, W. G.; Yuan, J. P.

2012-11-01

332

Exchange Energy as Functional of Electronic Density from Hartree-Fock Theory of Inhomogeneous Electron Gas  

Microsoft Academic Search

In a previous paper, the validity of gradient corrections to the Dirac-Slater exchange energy was discussed within the density functional theory, for a local potential. This local potential, by definition, generated the exact charge density in the (infinite) system considered. The present work considers the full Hartree-Fock theory within the same density functional framework. In particular, using a perturbation expansion

A. M. Beattie; J. C. Stoddart; N. H. March

1971-01-01

333

Coil planet centrifugation as a means for small particle separation  

NASA Technical Reports Server (NTRS)

The coil planet centrifuge uses a centrifugal force field to provide separation of particles based on differences in sedimentation rates by flow through a rotating coiled tube. Three main separations are considered: (1) single phase fresh sheep and human erythrocytes, (2) single phase fixed heep and human erythrocytes, and (3) electrophoretically enhanced single phase fresh sheep and human erythrocytes.

Herrmann, F. T.

1983-01-01

334

CENTRIPETAL ACCELERATION AND CENTRIFUGAL FORCE IN GENERAL RELATIVITY  

E-print Network

1 CENTRIPETAL ACCELERATION AND CENTRIFUGAL FORCE IN GENERAL RELATIVITY D. BINI Istituto per mechanics non-inertial observers studying accelerated test particle motion experience a centripetal acceleration which, once interpreted as a centrifugal force acting on the particle, allows writing the particle

Jantzen, Robert T.

335

View of new centrifuge at Flight Acceleration Facility  

NASA Technical Reports Server (NTRS)

View of the new centrifuge at the Manned Spacecraft Center (MSC), located in the Flight Acceleration Facility, bldg 29. The 50-ft. arm can swing the three man gondola to create g-forces astronauts will experience during controlled flight and during reentry. The centrifuge was designed primarily for training Apollo astronauts.

1966-01-01

336

Synaptic Connections of the Centrifugal Fibers in the Pigeon Retina  

Microsoft Academic Search

The centrifugal fibers in the pigeon retina end in the inner nuclear layer and form two kinds of terminals, convergent and divergent. In the inner nuclear layer the fibers synapse with amacrine and displaced ganglion cells. Because of their great number and their even distribution these fibers appear to constitute a system for the localized centrifugal control of the retinal

H. R. Maturana; S. Frenk

1965-01-01

337

Flow generation in a novel centrifugal diffuser test device  

Microsoft Academic Search

Recognition of the need to develop optimum diffusers for advanced centrifugal compressors, resulted in the design and manufacture of a novel low-speed test facility for centrifugal diffuser testing. The CDTD was designed to allow the flow angle and wall boundary profiles into the test diffuser to be controlled by variable geometry in the flow generator. The present study reports on

P. Vidos

1983-01-01

338

Visualizing Unsteady Vortical Behavior of a Centrifugal Pump Mathias Otto  

E-print Network

Visualizing Unsteady Vortical Behavior of a Centrifugal Pump Mathias Otto University of Magdeburg. The given data represents a high resolution simulation of a centrifugal pump used to transport liquids settings and physical context is described by Lucius et al. [1]. The main components of this device can

339

Development of a Low Flow Coefficient Single Stage Centrifugal Compressor  

Microsoft Academic Search

A low flow coefficient unshrouded centrifugal compressor would give up clearance in relation to the span of the blades, because centrifugal compressors produce a sufficiently large pressure rise in fewer stages. This problem is more acute for a low flow high-pressure ratio impeller. The large tip clearance would cause flow separations, and as a result it would drop both the

C. Xu; R. S. Amano

2009-01-01

340

Active surge control of centrifugal compressors using drive torque  

E-print Network

recycling, and there is a potential for reduced energy consumption of the compressor. Electric driveActive surge control of centrifugal compressors using drive torque Jan Tommy Gravdahl , Olav control is presented. A centrifugal compressor driven by an electrical motor is studied, and the drive

Gravdahl, Jan Tommy

341

A centrifugal pump concept designed for multiple use in space  

Microsoft Academic Search

A centrifugal pump concept was elaborated for a multiple application in future spacecrafts. Based on this concept a prototype of a small centrifugal pump was manufactured and comprehensively tested. The model pump has been approved in different test series with the fluids liquid ammonia and demineralized water. The design of the model pump was driven by strict requirements of COLUMBUS,

E. Wunderlich; H. G. Wulz

1993-01-01

342

Purification of mitochondria by sucrose step density gradient centrifugation.  

PubMed

Mitochondrial fractions isolated from tissue culture cells or tissue such as liver after differential centrifugation can be purified further by density gradient centrifugation. Here we describe the use of sucrose for this purpose because it is commonly used and inexpensive and the resulting mitochondria preparations are useful for many purposes. PMID:25275106

Clayton, David A; Shadel, Gerald S

2014-10-01

343

Settling velocities of particulate systems: 14. Unified model of sedimentation, centrifugation  

E-print Network

Settling velocities of particulate systems: 14. Unified model of sedimentation, centrifugation­liquid separation of flocculated suspensions including sedimentation- thickening, centrifugation and filtration. After identifying the variables and equations for each of the operations, thickening, centrifugation

Bürger, Raimund

344

Centrifuge Permeameter for Unsaturated Soils. II: Measurement of the Hydraulic Characteristics  

E-print Network

Centrifuge Permeameter for Unsaturated Soils. II: Measurement of the Hydraulic Characteristics and hydraulic conductivity function K function , determined using a new centrifuge permeameter developed hydraulic characteristics of the compacted clay. The SWRCs and K functions defined using the centrifuge

Zornberg, Jorge G.

345

77 FR 65360 - Grant of Authority for Subzone Status (Centrifugal and Submersible Pumps); Auburn, NY  

Federal Register 2010, 2011, 2012, 2013

...Subzone Status (Centrifugal and Submersible Pumps); Auburn, NY Pursuant to its authority...subzone at the centrifugal and submersible pump manufacturing and warehousing facilities...manufacturing of centrifugal and submersible pumps and related controllers at the Xylem...

2012-10-26

346

Quantitative Centrifugation To Extract Benthic Protozoa from Freshwater Sediments  

PubMed Central

Two methods for extracting protists from freshwater sediment are described: (i) an adapted isopycnic centrifugation technique for sandy and gyttja-like sediments and (ii) a rate zonal centrifugation technique for sediments rich in particulate organic material (litter-like sediments). The recoveries of protists during isopycnic centrifugation in media of several densities were compared. No significant losses in sodium diatrizoate and Percoll were recorded. After known amounts of nanoflagellates were added to azoic sediments, the protists were extracted and counted. For sandy sediments, we found 100% recovery, and for the gyttja-like sediments we found a maximum recovery of 94%. The recovery of protozoa extracted from litter-like sediments, characteristic of littoral systems, depends on a given centrifugal force, on time, and on the dimensions of the flagellates. A recovery model which takes into account cell dimensions and centrifugation characteristics gives the minimum expected recovery. PMID:16349148

Starink, Mathieu; Bär-Gilissen, Marie-José; Bak, Rolf P. M.; Cappenberg, Thomas E.

1994-01-01

347

Effect of science laboratory centrifuge of space station environment  

NASA Technical Reports Server (NTRS)

It is argued that it is essential to have a centrifuge operating during manned space station operations. Background information and a rationale for the research centrifuge are given. It is argued that we must provide a controlled acceleration environment for comparison with microgravity studies. The lack of control groups in previous studies throws into question whether the obseved effects were the result of microgravity or not. The centrifuge could be used to provide a 1-g environment to supply specimens free of launch effects for long-term studies. With the centrifuge, the specimens could be immediately transferred to microgravity without undergoing gradual acclimation. Also, the effects of artificial gravity on humans could be investigated. It is also argued that the presence of the centrifuge on the space station will not cause undo vibrations or other disturbing effects.

Searby, Nancy

1990-01-01

348

Measuring and balancing dynamic unbalance of precision centrifuge  

NASA Astrophysics Data System (ADS)

A precision centrifuge is used to test and calibrate accelerometer model parameters. Its dynamic unbalance may cause the perturbation of the centrifuge to deteriorate the test and calibration accuracy of an accelerometer. By analyzing the causes of dynamic unbalance, the influences on precision centrifuge from static unbalance and couple unbalance are developed. It is considered measuring and balancing of static unbalance is a key to resolving a dynamic unbalance problem of precision centrifuge with a disk in structure. Measuring means and calculating formulas of static unbalance amount are given, and balancing principle and method are provided. The correctness and effectiveness of this method are confirmed by experiments on a device under tuning, thereby the accurate and high-effective measuring and balancing method of dynamic unbalance of this precision centrifuge was provided.

Yang, Yafei; Huo, Xin

2008-10-01

349

Centrifugal regulator for control of deployment rates of deployable elements  

NASA Technical Reports Server (NTRS)

The requirements, design, and performance of a centrifugal regulator aimed at limiting deployment rates of deployable elements are discussed. The overall mechanism is comprised of four distinct functional parts in a machined housing: (1) the centrifugal brake device, which checks the payout of a deployment cable; (2) the reducing gear, which produces the spin rate necesary for the braking device; (3) the payout device, which allows the unwinding of the cable; and (4) the locking device, which prevents untimely unwinding. The centrifugal regulator is set into operation by a threshold tension of the cable which unlocks the mechanism and allows unwinding. The pulley of the windout device drives the centrifugal brake with the help of the reducing gear. The centrifugal force pushes aside weights that produce friction of the studs in a cylindrical housing. The mechanism behaved well at qualification temperature and vibrations.

Vermalle, J. C.

1980-01-01

350

Multiphase flow modeling in centrifugal partition chromatography.  

PubMed

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

Adelmann, S; Schwienheer, C; Schembecker, G

2011-09-01

351

Analysis of centrifugal convection in rotating pipes  

NASA Astrophysics Data System (ADS)

New exact solutions, obtained for centrifugal convection of a compressible fluid in pipes and annular pipes, explain axially elongated counterflow and energy separation—poorly understood phenomena occurring in vortex devices, e.g., hydrocyclones and Ranque tubes. Centrifugal acceleration (which can be up to 106 times gravity in practical vortex tubes), combined with an axial gradient of temperature (even small), induces an intense flow from the cold end to the hot end along the pipe wall and a backflow near the axis. To account for large density variations in vortex devices, we use the axial temperature gradient as a small parameter instead of the Boussinesq approximation. For weak pipe rotation, the swirl is of solid-body type and solutions are compact: vz/vza=1-4y2+3y4 and (T-Tw)/(Ta-Tw)=(1-y2)3; where y=r/rw, the subscripts w and a denote values of axial velocity vz, temperature T, and radial distance r, at the wall and on the axis. The axial gradient of pressure, being proportional to 3y2-1, has opposite directions near the wall, y=1, and near the axis, y=0; this explains the counterflow. With increasing pipe rotation, the flow starts to converge to the axis. This causes important new effects: (i) the density and swirl velocity maxima occur away from the wall (vortex core formation), (ii) the temperature near the axis becomes lower than near the wall (the Ranque effect), (iii) the axial gradient of temperature drops from the wall to the axis, and (iv) the total axial heat flux (Nu) reaches its maximum Numax?4000 and then decreases as swirl increases. These features can be exploited for the development of a micro-heat-exchanger, e.g., for cooling computer chips.

Shtern, Vladimir; Zimin, Valery; Hussain, Fazle

2001-08-01

352

Determination of the hydraulic characteristics of unsaturated soils using a centrifuge permeameter.  

E-print Network

??A new experimental approach to determine the hydraulic characteristics of unsaturated soils using a centrifuge permeameter was developed in this study. Specifically, the centrifuge permeameter… (more)

McCartney, John Scott, 1979-

2008-01-01

353

Application of convolution theory for solving non-linear flow problems: gas flow systems  

E-print Network

. . . . . . . . . . . . 15 3. 2. 1 Generalized Analytical Solution for Real Gas Systems . . . . . . . . 15 3. 2. 2 Dry Gas Material Balance Relations: P(tn) - g(u) Identity. . . . . . 16 3. 3 Functional and Numerical Data Models for the Non-Linear CHAPTER IV Component... 5 4. 6 4. 7 4. 8 4. 9 Numerical Model for the (/igcg);/(/tgcg) Data Function Based on Roumboutsos and Stewart Algorithm for Transforming Data into the Laplace Domain. . (p;cg, )/(peg) Versus (p/zj/(p, /z;) (y?= 0. 7 (air = 1. 0), T = 50 'F...

Mireles, Thomas Joseph

1995-01-01

354

Cyclic and acyclic fructose conformers in the gas phase: a large-scale second-order perturbation theory study.  

PubMed

We performed large-scale second-order perturbation theory gas-phase calculations to study about five hundred structures of D-fructose. The two lowest energy fructose structures identified are ?-pyranoses possessing (2)C5 chair, with ?G(298 K) of 6 kJ/mol, differing in orientation of the equatorially positioned hydroxymethyl group, gt and g'g, where the gt rotamer is the global minimum, consistent with the recent microwave spectroscopy study. We have found that interconversions from the fructose global minimum to the second and third most stable ?-pyranose rotamers involve the energy barriers of ca. 30 kJ/mol. Among numerous fructofuranose conformers discovered (about 250), a pair of the ((3)T2) ?- and (E3) ?-anomers are energetically most preferred and lie at least 12 kJ/mol above the global minimum. We also found that the fructose open-chain structures lie significantly higher in energy than the most stable cyclic species. The commonly used M06-2X density functional performs well compared to MP2 and G4 theory at identifying the low-energy fructose minima, including the global one, and at reproducing their intramolecular H-bond geometric parameters. The lowest-energy gas-phase pyranose and furanose structures of fructose benefit from stabilization due to the cooperative or quasi-linear H-bonding and both endo and exo anomeric effects. PMID:25110826

Szczepaniak, Marek; Moc, Jerzy

2014-09-11

355

Theories  

NSDL National Science Digital Library

This activity is designed to help building student understanding of how scientific theories can change over time. Science theories change in the face of new evidence. However, when new explanatory frameworks, or theories, are proposed to explain scientific phenomena, there is often a lengthy period during which groups of scientists use different competing theories to explain the same phenomena. During the activity, students are introduced to the geocentric and heliocentric models, students compare the two models, and then observe the time it took to change the theory underpinning the heliocentric model. This activity is part of the "Swift: Eyes through Time" collection that is available on the Teacher's Domain website.

356

Experimental characterization of high speed centrifugal compressor aerodynamic forcing functions  

NASA Astrophysics Data System (ADS)

The most common and costly unexpected post-development gas turbine engine reliability issue is blade failure due to High Cycle Fatigue (HCF). HCF in centrifugal compressors is a coupled nonlinear fluid-structure problem for which understanding of the phenomenological root causes is incomplete. The complex physics of this problem provides significant challenges for Computational Fluid Dynamics (CFD) techniques. Furthermore, the available literature fails to address the flow field associated with the diffuser potential field, a primary cause of forced impeller vibration. Because of the serious nature of HCF, the inadequacy of current design approaches to predict HCF, and the fundamental lack of benchmark experiments to advance the design practices, there exists a need to build a database of information specific to the nature of the diffuser generated forcing function as a foundation for understanding flow induced blade vibratory failure. The specific aim of this research is to address the fundamental nature of the unsteady aerodynamic interaction phenomena inherent in high-speed centrifugal compressors wherein the impeller exit flow field is dynamically modulated by the vaned diffuser potential field or shock structure. The understanding of this unsteady aerodynamic interaction is fundamental to characterizing the impeller forcing function. Unsteady static pressure measurement at several radial and circumferential locations in the vaneless space offer a depiction of pressure field radial decay, circumferential variation and temporal fluctuation. These pressure measurements are coupled with high density, full field measurement of the velocity field within the diffuser vaneless space at multiple spanwise positions. The velocity field and unsteady pressure field are shown to be intimately linked. A strong momentum gradient exiting the impeller is shown to extend well across the vaneless space and interact with the diffuser vane leading edge. The deterministic unsteady pressure field is found to be dominated by the blade-vane interaction. HCF concerns are illuminated by persistent pressure waves extending radially across the vaneless space and impacting the impeller pressure surface. Finally, the average impeller exit flow field is found to present a highly unsteady velocity field to the downstream vane row, challenging the common design assumption of a rapid mixing model for diffuser design.

Gallier, Kirk

357

DIFFUSION THEORY IMPROVES CHAMBER-BASED MEASUREMENTS OF TRACE GAS EMISSIONS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Chambers temporarily sealed to the soil surface are an important and for many purposes the only means of measuring trace gas emissions to the atmosphere. However, past interpretations of chamber data systematically underestimated actual emission rates in most applications because they ignored or poo...

358

GasKinetic Theory Based Flux Splitting Method for Ideal Magnetohydrodynamics  

E-print Network

to the MHD equations has not been fully addressed. The search for robust, accurate and efficient MHD flow Abstract A gas­kinetic flux splitting method is developed for the ideal magnetohydrodynamics (MHD) equa­ tions. The new scheme is based on the direct splitting of the flux function of the MHD equations

Xu, Kun

359

Tropic responses of Phycomyces sporangiophores to gravitational and centrifugal stimuli.  

PubMed

A low-speed centrifuge was used to study the tropic responses of Phycomyces sporangiophores in darkness to the stimulus of combined gravitational and centrifugal forces. If this stimulus is constant the response is a relatively slow tropic reaction, which persists for up to 12 hours. The response is accelerated by increasing the magnitude of the gravitational-centrifugal force. A wholly different tropic response, the transient response, is elicited by an abrupt change in the gravitational-centrifugal stimulus. The transient response has a duration of only about 6 min. but is characterized by a high bending speed (about 5 degrees /min.). An analysis of the distribution of the transient response along the growing zone shows that the active phase of the response has a distribution similar to that of the light sensitivity for the light-growth and phototropic responses. Experiments in which sporangiophores are centrifuged in an inert dense fluid indicate that the sensory mechanism of the transient response is closely related to the physical deformation of the growing zone caused by the action of the gravitational-centrifugal force on the sporangiophore as a whole. However, the response to a steady gravitational-centrifugal force is most likely not connected with this deformation, but is probably triggered by the shifting of regions or particles of differing density relative to one another inside the cell. PMID:13721903

DENNISON, D S

1961-09-01

360

Tropic Responses of Phycomyces Sporangiophores to Gravitational and Centrifugal Stimuli  

PubMed Central

A low-speed centrifuge was used to study the tropic responses of Phycomyces sporangiophores in darkness to the stimulus of combined gravitational and centrifugal forces. If this stimulus is constant the response is a relatively slow tropic reaction, which persists for up to 12 hours. The response is accelerated by increasing the magnitude of the gravitational-centrifugal force. A wholly different tropic response, the transient response, is elicited by an abrupt change in the gravitational-centrifugal stimulus. The transient response has a duration of only about 6 min. but is characterized by a high bending speed (about 5°/min.). An analysis of the distribution of the transient response along the growing zone shows that the active phase of the response has a distribution similar to that of the light sensitivity for the light-growth and phototropic responses. Experiments in which sporangiophores are centrifuged in an inert dense fluid indicate that the sensory mechanism of the transient response is closely related to the physical deformation of the growing zone caused by the action of the gravitational-centrifugal force on the sporangiophore as a whole. However, the response to a steady gravitational-centrifugal force is most likely not connected with this deformation, but is probably triggered by the shifting of regions or particles of differing density relative to one another inside the cell. PMID:13721903

Dennison, David S.

1961-01-01

361

Centrifugal distortion and the ring puckering vibration in the microwave spectrum of 2,3-dihydrofuran  

NASA Astrophysics Data System (ADS)

The microwave spectrum of 2,3-dihydrofuran has been reinvestigated and measurements for the ground and first five excited states of the ring puckering vibration have been extended to higher frequencies and rotational quantum numbers in order to study the vibrational dependence of the rotational and centrifugal distortion constants. The ring puckering potential function derived by Green from the far infrared spectrum does not reproduce the vibrational dependence of the rotational constants well. A slightly different potential function is derived which gives a reasonable fit both to the far infrared spectrum and the rotational constants. This changes the barrier to ring inversion from 1.00 kJ mol -1 to 1.12 kJ mol -1. The vibrational dependence of the centrifugal distortion constants is accounted for satisfactorily by the theory developed by Creswell and Mills. An attempt to reproduce the vibrational dependence of the rotational and centrifugal distortion constants using the ring puckering potential function and a simple model for this vibration has very limited success.

Cervellati, R.; Degli Esposti, A.; Lister, D. G.; Lopez, J. C.; Alonso, J. L.

1986-10-01

362

Magnetically driven solid sample preparation for centrifugal microfluidic devices.  

PubMed

A prototype for solid sample preparation on centrifugal microfluidic devices has been designed and characterized. The system uses NdFeB magnets in both the centrifugal device and a fixed base. As the centrifugal device rotates, the magnets move and spin in their chambers creating a pulverizing mechanical motion. This technique was successfully applied to the dissolution of potassium ferricyanide (K(3)[Fe(CN)(6)]), a hard colored crystal. A 0.10 g sample was completely dissolved in 3 s in 1.0 mL of water while rotating at 1000 rpm. This is a 300-fold improvement over static dissolution. PMID:19422186

Duford, David A; Peng, Dan D; Salin, Eric D

2009-06-01

363

Ocular counterrolling induced by centrifugation during orbital space flight  

NASA Technical Reports Server (NTRS)

During the 1998 Neurolab mission (STS-90), four astronauts were exposed to interaural centripetal accelerations (Gy centrifugation) of 0.5 g and 1 g during rotation on a centrifuge, both on Earth and during orbital space flight. Subjects were oriented either left-ear out or right-ear out, facing or back to motion. Binocular eye movements were measured in three dimensions using a video technique. On Earth, tangential centrifugation that produces 1 g of interaural linear acceleration combines with gravity to tilt the gravitoinertial acceleration (GIA) vector 45 degrees in the roll plane relative to the head vertical, generating a summed vector of 1.4 g. Before flight, this elicited mean ocular counterrolling (OCR) of 5.7 degrees. Due to the relative absence of gravity during flight, there was no linear acceleration along the dorsoventral axis of the head. As a result, during in-flight centrifugation, gravitoinertial acceleration was strictly aligned with the centripetal acceleration along the interaural axis. There was a small but significant decrease (mean 10%) in the magnitude of OCR in space (5.1 degrees). The magnitude of OCR during postflight 1 g centrifugation was not significantly different from preflight OCR (5.9 degrees). Findings were similar for 0.5 g centrifugation, but the OCR magnitude was approximately 60% of that induced by centrifugation at 1 g. OCR during pre- and postflight static tilt was not significantly different and was always less than OCR elicited by centrifugation of Earth for an equivalent interaural linear acceleration. In contrast, there was no difference between the OCR generated by in-flight centrifugation and by static tilt on Earth at equivalent interaural linear accelerations. These data support the following conclusions: (1) OCR is generated predominantly in response to interaural linear acceleration; (2) the increased OCR during centrifugation on Earth is a response to the head dorsoventral 1 g linear acceleration component, which was absent in microgravity. The dorsoventral linear acceleration could have activated either the otoliths or body-tilt receptors that responded to the larger GIA magnitude (1.4 g), to generate the increased OCR during centrifugation on Earth. A striking finding was that magnitude of OCR was maintained throughout and after flight. This is in contrast to most previous postflight OCR studies, which have generally registered decreases in OCR. We postulate that intermittent exposure to artificial gravity, in the form of the centripetal acceleration experienced during centrifugation, acted as a countermeasure to deconditioning of this otolith-ocular orienting reflex during the 16-day mission.

Moore, S. T.; Clement, G.; Raphan, T.; Cohen, B.

2001-01-01

364

Research on 3-D discharge flow in a centrifugal impeller  

NASA Astrophysics Data System (ADS)

A method for calculating 3D discharge flow in a centrifugal impeller is developed by means of solving the incompressible steady time-averaged N-S equations, the continuity equation, and the k-epsilon turbulence model equation. This method is accomplished with calculation grids generated by an algebraic transformation, and thus it can be easily applied to the design analysis of centrifugal impellers. The discharge flow of a three-dimensional shrouded centrifugal compressor impeller was measured for assessing the validity of the present calculation procedure. The comparison between the experimental data and the calculation results shows that the present method can predict the mean velocities.

Xi, Guang; Wang, Shangjin

1993-01-01

365

27. RW Meyer Sugar Mill: 18761889. Centrifugals, 1879, 1881. Manufacturer, ...  

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

27. RW Meyer Sugar Mill: 1876-1889. Centrifugals, 1879, 1881. Manufacturer, Unknown. Supplied by Honolulu Ironworks, Honolulu Hawaii, 1879, 1881. View: Historical view, 1934, from T.T. Waterman collection, Hawaiian Sugar Planters' Association. With the inner basket of the centrifugal revolving at 1200 rpm molasses flew outward from the granulated sugar, through the holes in the brass lining, and into the stationary outer basket. The molasses drained through the spout at the right and into molasses storage pits below the floor. The centrifugals were underdriven with a belt connected to the pulley beneath the basket. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

366

Thermal Creep of a Rarefied Gas on the Basis of Non-linear Korteweg-Theory  

NASA Astrophysics Data System (ADS)

The study of thermal transpiration, more commonly called thermal creep, is accomplished by use of Korteweg's theory of capillarity. Incorporation of this theory into the balance laws of continuum mechanics allows resolution of boundary value problems via solutions to systems of ordinary differential equations. The problem was originally considered by Maxwell in his classic 1879 paper M axwell (Phil Trans Roy Soc (London) 170:231-256, 1879). In that paper Maxwell derived what is now called the Burnett higher order contribution to the Cauchy stress, but was not able to solve his newly derived system of partial differential equations. In this paper the authors note that a more appropriate higher order contribution to the Cauchy stress follows from Korteweg's 1901 theory K orteweg (Arch Neerl Sci Exactes Nat Ser II 6:1-24, 1901). The appropriateness of Korteweg's theory is based on the exact summation of the Chapman-Enskog expansion given by Gorban and Karlin. The resulting balance laws are solved exactly, qualitatively, and numerically and the results are qualitatively similar to the numerical and exact results given by Aoki et al., Loyalka et al., and Struchtrup et al.

Kim, Yong-Jung; Lee, Min-Gi; Slemrod, Marshall

2015-02-01

367

Analytical theory of mesoscopic Bose-Einstein condensation in an ideal gas  

Microsoft Academic Search

We find the universal structure and scaling of the Bose-Einstein condensation (BEC) statistics and thermodynamics (Gibbs free energy, average energy, heat capacity) for a mesoscopic canonical-ensemble ideal gas in a trap with an arbitrary number of atoms, any volume, and any temperature, including the whole critical region. We identify a universal constraint-cutoff mechanism that makes BEC fluctuations strongly non-Gaussian and

Vitaly V. Kocharovsky; Vladimir V. Kocharovsky

2010-01-01

368

Single gas permeation of thin zeolite (MFI) membranes: theory and analysis of experimental observations  

Microsoft Academic Search

Theoretical expressions for single gas permeation are analysed and evaluated with selected literature and some new experimental data on Silicalite\\/ZSM-5 membranes. The phenomenological sorption–diffusion (PSD) description (and its equivalent Maxwell–Stefan equation) covers both the microscopic models based on configurational diffusion (CD) with ?=1.0 and on surface diffusion (SD) with ??1.24. The ratio ? of the pore diameter over the (kinetic)

A. J. Burggraaf

1999-01-01

369

Lattice gas hydrodynamics: Theory and simulations. Final report, [February 1, 1989--March 31, 1991  

SciTech Connect

The first successful application of a microscopic analogy to create a skeleton cellular automaton and analyze it with statistical mechanical tools, was the work of Frisch, Hasslacher and Pomeau on the Navier-Stokes equation in two and three dimensions. This has become a very large research area with lattice gas models and methods being used for both fundamental investigations into the foundations of statistical mechanics and a large number of diverse applications. This present research was devoted to enlarging the fundamental scope of lattice gas models and proved successful. Since the beginning of this proposal, cellular automata have been constructed for statistical mechanical models, fluids, diffusion and shock systems in fundamental investigations. In applied areas, there are now excellent lattice gas models for complex flows through porous media, chemical reaction and combustion dynamics, multiphase flow systems, and fluid mixtures with natural boundaries. With extended cellular fluid models, one can do problems with arbitrary pairwise potentials. Recently, these have been applied to such problems as non-newtonian or polymeric liquids and a mixture of immiscible fluids passing through fractal or spongelike media in two and three dimensions. This proposal has contributed to and enlarged the scope of this work.

Hasslacher, B.

1993-05-01

370

Single stage high pressure centrifugal slurry pump  

DOEpatents

Apparatus is shown for feeding a slurry to a pressurized housing. An impeller that includes radial passages is mounted in the loose fitting housing. The impeller hub is connected to a drive means and a slurry supply means which extends through the housing. Pressured gas is fed into the housing for substantially enveloping the impeller in a bubble of gas.

Meyer, John W. (Palo Alto, CA); Bonin, John H. (Sunnyvale, CA); Daniel, Arnold D. (Alameda, CA)

1984-03-27

371

Hybridization enhancement using microfluidic planetary centrifugal mixing.  

PubMed

DNA microarrays produce their greatest sensitivities when hybridized using concentrated samples and effective mixing; however, these goals have proved elusive to combine. If samples are diluted enough to fill larger chambers, then mixing works well using either pumping or gravity with rotation, although sensitivities will suffer. Various techniques for mixing concentrated samples in small thin chambers have been proposed; however, they often leave streaks or scars, and their reusable components require careful cleaning. Here we introduce a versatile new microfluidics platform, a two-axis centrifuge whose fluidic chambers rotate in a planetary relationship to a radial gravitational field. This paradigm readily overcomes surface and viscous forces even in chambers only 50 microm thin. Thin chambers obviate the need for sample dilution and increase sensitivities and dynamic ranges 10-fold. In comparisons against conventional mixing using the same 10 microg of starting total RNA on 22 000-probe arrays, 10 000 more usable signals rose above the noise. In other experiments, planetary mixing was able to produce comparable results while using only one-tenth the starting sample. The benefits of planetary mixing include sample conservation, shorter hybridizations, less reliance on amplification, and the ability to quantify many gene signals otherwise obscured by noise. PMID:15571357

Bynum, Magdalena A; Gordon, Gary B

2004-12-01

372

Wave Augmented Diffuser for Centrifugal Compressor  

NASA Technical Reports Server (NTRS)

A wave augmented diffuser for a centrifugal compressor surrounds the outlet of an impeller that rotates on a drive shaft having an axis of rotation. The impeller brings flow in in an axial direction and imparts kinetic energy to the flow discharging it in radial and tangential directions. The flow is discharged into a plurality of circumferentially disposed wave chambers. The wave chambers are periodically opened and closed by a rotary valve such that the flow through the diffuser is unsteady. The valve includes a plurality of valve openings that are periodically brought into and out of fluid communication with the wave chambers. When the wave chambers are closed, a reflected compression wave moves upstream towards the diffuser bringing the flow into the wave chamber to rest. This action recovers the kinetic energy from the flow and limits any boundary layer growth. The flow is then discharged in an axial direction through an opening in the valve plate when the valve plate is rotated to an open position. The diffuser thus efficiently raises the static pressure of the fluid and discharges an axially directed flow at a radius that is predominantly below the maximum radius of the diffuser.

Skoch, Gary J. (Inventor); Paxson, Daniel E. (Inventor)

2001-01-01

373

Cross plane transfer of vestibular adaptation to human centrifugation  

E-print Network

Human short-radius centrifugation (SRC) is being investigated as a volume-efficient means of delivering intermittent doses of "artificial gravity" to counter the deleterious effects of long exposures to weightlessness. ...

Garrick-Bethell, Ian, 1980-

2004-01-01

374

Looking Southeast at Precipitation System, Steam Dryer and Centrifuge in ...  

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

Looking Southeast at Precipitation System, Steam Dryer and Centrifuge in Red Room within Recycle Recovery Building - Hematite Fuel Fabrication Facility, Recycle Recovery Building, 3300 State Road P, Festus, Jefferson County, MO

375

Astronaut Alan Shepard prepares for testing in centrifuge  

NASA Technical Reports Server (NTRS)

Astronaut Alan B. Shepard Jr., one of three NASA astronauts chosen for the Project Mercury first manned suborbital flight, prepares for testing in capsule of the U.S. Navy's centrifuge at Johnsville, Pennsylvania.

1961-01-01

376

Centrifuge modeling of LNAPL transport in partially saturated sand  

SciTech Connect

Model tests were performed at the Geotechnical Centrifuge Facility of Delft University of Technology, The Netherlands, to examine the mechanics of light nonaqueous phase liquid (LNAPL) movement in a partially saturated porous granular medium. The experiment simulated a 2D spill of LNAPL in an unsaturated sand prepared at two values of porosity. The duration of the centrifuge model tests corresponded to a prototype equivalent of 110 days. The choice of modeling a 2D flow together with the use of a transparent container enabled direct visual observation of the experiments. Scaling laws developed in connection with other centrifuge modeling studies were used to support the test results. Tests were conducted at two different centrifuge accelerations to verify, by means of the modeling of models technique, the similitude between the different experiments. The paper presents details of the experimental methodologies and the measuring techniques used to evaluate the final distribution of water and LNAPL content in the soils.

Esposito, G.; Allersma, H.G.B.; Selvadurai, A.P.S.

1999-12-01

377

Biomolecule delivery into canola protoplasts by centrifuging cells with microbubbles.  

PubMed

We have successfully delivered FITC and FITC-Dextran (70, 250 kDa) into canola protoplasts by centrifuging cells with different amounts of microbubbles at variable centrifuge speed. The efficiency is around 90%, while cell viability remains high. Confocal microscopy images show that both FITC and FITC-Dextran are scattered inside the cytoplasm and the cell nucleus. Pores are observed on canola protoplast cell membranes and cell walls when centrifuged with microbubbles, while the membrane of cells centrifuged alone remain intact and smooth. We hypothesize that the collision between the microbubbles and cells or the bursting of microbubbles are the main reasons for the formation of these pores. Biomaterials can diffuse into the cells once the pathway is created. PMID:23262220

He, Chuan; Gu, Quanrong; Huang, Min; Xing, James; Chen, Jie

2013-01-31

378

Isolation and retrieval of circulating tumor cells using centrifugal forces  

E-print Network

Presence and frequency of rare circulating tumor cells (CTCs) in bloodstreams of cancer patients are pivotal to early cancer detection and treatment monitoring. Here, we use a spiral microchannel with inherent centrifugal ...

Hou, Han Wei

379

19. LOWER OIL ROOM DIABLO POWERHOUSE: SHARPLES OIL CENTRIFUGE AND ...  

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

19. LOWER OIL ROOM DIABLO POWERHOUSE: SHARPLES OIL CENTRIFUGE AND OIL TANK, 1989. - Skagit Power Development, Diablo Powerhouse, On Skagit River, 6.1 miles upstream from Newhalem, Newhalem, Whatcom County, WA

380

Centrifugal compressor return channel shape optimization using adjoint method  

E-print Network

This thesis describes the construction of an automated gradient-based optimization process using the adjoint method and its application to centrifugal compressor return channel loss reduction. A proper objective function ...

Guo, Wei, S.M. Massachusetts Institute of Technology

2013-01-01

381

Forced response predictions in modern centrifugal compressor design  

E-print Network

A computational interrogation of the time-averaged and time-unsteady flow fields of two centrifugal compressors of nearly identical design (the enhanced, which encountered aeromechanical difficulty, and production, which ...

Smythe, Caitlin J. (Caitlin Jeanne)

2005-01-01

382

Return channel loss reduction in multi-stage centrifugal compressors  

E-print Network

This thesis presents concepts for improving the performance of return channels in multi-stage centrifugal compressors. Geometries have been developed to reduce both separation and viscous losses. A number of different ...

Aubry, Anne-Raphaëlle

2012-01-01

383

A multiplexed immunoassay system based upon reciprocating centrifugal microfluidics  

NASA Astrophysics Data System (ADS)

A novel, centrifugal disk-based micro-total analysis system (?TAS) for low cost and high throughput semi-automated immunoassay processing was developed. A key innovation in the disposable immunoassay disk design is in a fluidic structure that enables very efficient micro-mixing based on a reciprocating mechanism in which centrifugal acceleration acting upon a liquid element first generates and stores pneumatic energy that is then released by a reduction of the centrifugal acceleration, resulting in a reversal of direction of flow of the liquid. Through an alternating sequence of high and low centrifugal acceleration, the system reciprocates the flow of liquid within the disk to maximize incubation/hybridization efficiency between antibodies and antigen macromolecules during the incubation/hybridization stage of the assay. The described reciprocating mechanism results in a reduction in processing time and reagent consumption by one order of magnitude.

Noroozi, Zahra; Kido, Horacio; Peytavi, Régis; Nakajima-Sasaki, Rie; Jasinskas, Algimantas; Micic, Miodrag; Felgner, Philip L.; Madou, Marc J.

2011-06-01

384

Multi-parameter control for centrifugal compressor performance optimization  

E-print Network

The potential performance benefit of actuating inlet guide vane (IGV) angle, variable diffuser vane (VDV) angle and impeller speed to implement a multi-parameter control on a centrifugal compressor system is assessed. The ...

Mannai, Sébastien (Sébastien Karim)

2014-01-01

385

Centrifuge Facility for the International Space Station Alpha  

NASA Technical Reports Server (NTRS)

The Centrifuge Facility planned for the International Space Station Alpha has under-one considerable redesign over the past year, primarily because the Station is now viewed as a 10 year mission rather than a 30 year mission and because of the need to simply the design to meet budget constraints and a 2000 launch date. The basic elements of the Centrifuge Facility remain the same, i.e., a 2.5 m diameter centrifuge, a micro-g holding unit, plant and animal habitats, a glovebox and a service unit. The centrifuge will still provide the full range of artificial gravity from 0.01 a to 2 - as originally planned; however, the extractor to permit withdrawal of habitats from the centrifuge without stopping the centrifuge has been eliminated. The specimen habitats have also been simplified and are derived from other NASA programs. The Plant Research Unit being developed by the Gravitational Biology Facility will be used to house plants in the Centrifuge Facility. Although not as ambitious as the Centrifuge Facility plant habitat, it will provide much better environmental control and lighting than the current Shuttle based Plant Growth Facility. Similarly, rodents will be housed in the Advanced Animal Habitat being developed for the Shuttle program. The Centrifuge Facility and ISSA will provide the opportunity to perform repeatable, high quality science. The long duration increments available on the Station will permit multigeneration studies on both plants and animals which have not previously been possible. The Centrifuge Facility will accommodate sufficient number of specimens to permit statistically significant sampling of specimens to investigate the time course of adaptation to altered gravity environments. The centrifuge will for the first time permit investigators to use gravity itself as a tool to investigate fundamental processes, to investigate the intensity and duration of gravity to maintain normal structure and function, to separate the effects of micro-g from other 0 environmental factors and to examine artificial gravity as a potential countermeasure for the physical deconditioning observed during spaceflight.

Johnson, Catherine C.; Hargens, Alan R.

1994-01-01

386

The magnetic centrifugal mass filter Abraham J. Fetterman and Nathaniel J. Fisch  

E-print Network

The magnetic centrifugal mass filter Abraham J. Fetterman and Nathaniel J. Fisch Department centrifugal and magnetic confinement of ions in a way similar to the asymmetric centrifugal trap. This magnetic centrifugal mass filter is shown to be more proliferation resistant than present technology

387

Improving electrotransfection efficiency by post-pulse centrifugation  

Microsoft Academic Search

We have demonstrated that the viability of electrotransfected adherent CHO and suspended NK-L, K-562, L1210 and MC2 cells is improved if pelleting by centrifugation is performed immediately after pulsing. The protection effect on cell viability is cell line- and pellet thickness-dependent. For forming CHO cell pellets, centrifugation force (300–13000 g) and duration are not crucial; about five to 10 cell

L H Li; P Ross; S W Hui

1999-01-01

388

Steady-state model of centrifugal liquid chillers  

Microsoft Academic Search

A new steady-state model of vapour-compression type centrifugal liquid chillers is presented. The model has a number of advanced features and is capable of simulating both hermetic and open-drive centrifugal compressors. The model accounts for the real process phenomena such as superheating and subcooling in the heat exchangers as well as a capacity control formulation of the inlet guide vanes.

M. W. Browne; P. K. Bansal

1998-01-01

389

Transport modes during crystal growth in a centrifuge  

NASA Technical Reports Server (NTRS)

Flow modes arising under average acceleration in centrifugal crystal growth, the gradient of acceleration, and the Coriolis force are investigated using a fully nonlinear three-dimensional numerical model for a centrifugal crystal growth experiment. The analysis focuses on an examination of the quasi-steady state flow modes. The importance of the gradient acceleration is determined by the value of a new nondimensional number, Ad.

Arnold, William A.; Wilcox, William R.; Carlson, Frederick; Chait, Arnon; Regel', Liia L.

1992-01-01

390

The design and performance of a centrifugal compressor research facility  

Microsoft Academic Search

The objective of this research has been to develop an advanced high-speed, high performance centrifugal compressor research facility and obtain the baseline performance map. This facility utilizes a Rolls-Royce production model C28 centrifugal compressor from the Rolls-Royce 250 turboshaft engine used on helicopters. The compressor is powered by a 1400 hp AC motor and a variable frequency drive. The high

Ryan Michael Fleming

2010-01-01

391

Research on 3-D discharge flow in a centrifugal impeller  

Microsoft Academic Search

A method for calculating 3D discharge flow in a centrifugal impeller is developed by means of solving the incompressible steady time-averaged N-S equations, the continuity equation, and the k-epsilon turbulence model equation. This method is accomplished with calculation grids generated by an algebraic transformation, and thus it can be easily applied to the design analysis of centrifugal impellers. The discharge

Guang Xi; Shangjin Wang

1993-01-01

392

Noise as an indicator of cavitation in a centrifugal pump  

Microsoft Academic Search

One of the sources of instability in a centrifugal pump is cavitation within the pump. Cavitation of a centrifugal pump is\\u000a the result of insufficient net positive suction head (NPSH) and can occur within the entire range of operating conditions.\\u000a Cavitation may cause three different and undesirable effects: (1) a drop in head-capacity and efficiency curves, (2) damage\\u000a to the

M. Chudina

2003-01-01

393

Theory of Electrocaloric Effect in a Shape-Changing Container: Gas in a Nanotube  

NASA Astrophysics Data System (ADS)

Driven by applied voltage or Ohmic heating, bistable nanotubes filled with gas can transform between expanded and collapsed configurations and by doing so convert energy between mechanical, electrical, and thermal forms. The electrocaloric response, a reversible change of temperature in response to applied voltage, combines the advantages of a working fluid with the lack of internal interfaces characteristic of robust solid-state thermoelectric devices. Such devices could be constructed from any conductive two-dimensional atomically thin material wrapped into an appropriate geometry.

Shklyaev, Oleg E.; Mockensturm, Eric; Cole, Milton W.; Crespi, Vincent H.

2014-12-01

394

Kinetic theory analysis of rarefied gas flow through finite length slots  

NASA Technical Reports Server (NTRS)

An analytic study is made of the flow a rarefied monatomic gas through a two dimensional slot. The parameters of the problem are the ratios of downstream to upstream pressures, the Knudsen number at the high pressure end (based on slot half width) and the length to slot half width ratio. A moment method of solution is used by assuming a discontinuous distribution function consisting of four Maxwellians split equally in angular space. Numerical solutions are obtained for the resulting equations. The characteristics of the transition regime are portrayed. The solutions in the free molecule limit are systematically lower than the results obtained in that limit by more accurate numerical methods.

Raghuraman, P.

1972-01-01

395

A Unified Theory of Non-Ideal Gas Lattice Boltzmann Models  

NASA Technical Reports Server (NTRS)

A non-ideal gas lattice Boltzmann model is directly derived, in an a priori fashion, from the Enskog equation for dense gases. The model is rigorously obtained by a systematic procedure to discretize the Enskog equation (in the presence of an external force) in both phase space and time. The lattice Boltzmann model derived here is thermodynamically consistent and is free of the defects which exist in previous lattice Boltzmann models for non-ideal gases. The existing lattice Boltzmann models for non-ideal gases are analyzed and compared with the model derived here.

Luo, Li-Shi

1998-01-01

396

Probability theory for 3-layer remote sensing in ideal gas law environment.  

PubMed

We extend the probability model for 3-layer radiative transfer [Opt. Express 20, 10004 (2012)] to ideal gas conditions where a correlation exists between transmission and temperature of each of the 3 layers. The effect on the probability density function for the at-sensor radiances is surprisingly small, and thus the added complexity of addressing the correlation can be avoided. The small overall effect is due to (a) small perturbations by the correlation on variance population parameters and (b) cancellation of perturbation terms that appear with opposite signs in the model moment expressions. PMID:24105525

Ben-David, Avishai; Davidson, Charles E

2013-08-26

397

A complete theory for the magnetism of an ideal gas of electrons  

SciTech Connect

We have explored Pauli paramagnetism, Landau diamagnetism, and de Haas-van Alphen effect in a single framework, and unified these three effects for all temperatures as well as for all strengths of magnetic field. Our result goes beyond Pauli-Landau result on the magnetism of the 3-D ideal gas of electrons, and is able to describe crossover of the de Haas-van Alphen oscillation to the saturation of magnetization. We also have obtained a novel asymptotic series expansion for the low temperature properties of the system.

Biswas, Shyamal; Jana, Debnarayan [Department of Physics, University of Calcutta, 92 APC Road, Kolkata 700009 (India)] [Department of Physics, University of Calcutta, 92 APC Road, Kolkata 700009 (India); Sen, Swati [Department of Physical Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur 741252 (India)] [Department of Physical Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur 741252 (India)

2013-05-15

398

Emission from the Centrifugal Magnetospheres of Magnetic B-type Stars  

E-print Network

Approximately 10% of B-type stars possess strong magnetic fields, and of these, 25% host centrifugal magnetospheres (CMs) in which the radiative wind, magnetic field, and rotational support interact to form a dense circumstellar plasma visible in a variety of diagnostic lines. In this article we review the basic theory behind CMs, outline current theoretical and observational problems, compare the observational properties of CM host stars to those of classical Be stars, and finally present preliminary results of a population study aimed at clarifying the characteristics of this growing sub-class.

Shultz, Matt; Rivinius, Thomas; Townsend, Richard

2014-01-01

399

Investigation of the jet-wake flow of a highly loaded centrifugal compressor impeller  

NASA Technical Reports Server (NTRS)

Investigations, aimed at developing a better understanding of the complex flow field in high performance centrifugal compressors were performed. Newly developed measuring techniques for unsteady static and total pressures as well as flow directions, and a digital data analysis system for fluctuating signals were thoroughly tested. The loss-affected mixing process of the distorted impeller discharge flow was investigated in detail, in the absolute and relative system, at impeller tip speeds up to 380 m/s. A theoretical analysis proved good coincidence of the test results with the DEAN-SENOO theory, which was extended to compressible flows.

Eckardt, D.

1978-01-01

400

Density Functional Theory and Reaction Kinetics Studies of the Water–Gas Shift Reaction on Pt–Re Catalysts  

SciTech Connect

Periodic, self-consistent density functional theory calculations (DFT-GGA-PW91) on Pt(111) and Pt3Re(111) surfaces, reaction kinetics measurements, and microkinetic modeling are employed to study the mechanism of the water–gas shift (WGS) reaction over Pt and Pt–Re catalysts. The values of the reaction rates and reaction orders predicted by the model are in agreement with the ones experimentally determined; the calculated apparent activation energies are matched to within 6% of the experimental values. The primary reaction pathway is predicted to take place through adsorbed carboxyl (COOH) species, whereas formate (HCOO) is predicted to be a spectator species. We conclude that the clean Pt(111) is a good representation of the active site for the WGS reaction on Pt catalysts, whereas the active sites on the Pt–Re alloy catalyst likely contain partially oxidized metal ensembles.

Carrasquillo-Flores, Ronald; Gallo, Jean Marcel R.; Hahn, Konstanze; Dumesic, James A.; Mavrikakis, Manos

2013-12-01

401

Synchronization of mammalian cells and nuclei by centrifugal elutriation.  

PubMed

Synchronized populations of large numbers of cells can be obtained by centrifugal elutriation on the basis of sedimentation properties of small round particles, with minimal perturbation of cellular functions. The physical characteristics of cell size and sedimentation velocity are operative in the technique of centrifugal elutriation also known as counterstreaming centrifugation. The elutriator is an advanced device for increasing the sedimentation rate to yield enhanced resolution of cell separation. A random population of cells is introduced into the elutriation chamber of an elutriator rotor running in a specially designed centrifuge. By increasing step by step the flow rate of the elutriation fluid, successive populations of relatively homogeneous cell size can be removed from the elutriation chamber and used as synchronized subpopulations. For cell synchronization by centrifugal elutriation early log S phase cell populations are most suitable where most of the cells are in G1 and S phase (>80%). Protocols for the synchronization of nuclei of murine pre-B cells and high-resolution centrifugal elutriation of CHO cells are given. The verification of purity and cell cycle positions of cells in elutriated fractions includes the measurement of DNA synthesis by [(3)H]-thymidine incorporation and DNA content by propidium iodide flow cytometry. PMID:21755439

Banfalvi, Gaspar

2011-01-01

402

Fabrication of Al/Diamond Particles Functionally Graded Materials by Centrifugal Sintered-Casting Method  

NASA Astrophysics Data System (ADS)

The continuous graded structure of functionally graded materials (FGMs) can be created under a centrifugal force. Centrifugal sintered-casting (CSC) method, proposed by the authors, is one of the fabrication methods of FGM under centrifugal force. This method is a combination of the centrifugal sintering method and centrifugal casting method. In this study, Al/diamond particle FGM was fabricated by the proposed method.

Watanabe, Yoshimi; Shibuya, Masafumi; Sato, Hisashi

2013-03-01

403

Cerebral Hypoperfusion Precedes Nausea During Centrifugation  

NASA Technical Reports Server (NTRS)

Nausea and motion sickness are important operational concerns for aviators and astronauts. Understanding underlying mechanisms associated with motion sickness may lead to new treatments. The goal of this work was to determine if cerebral blood flow changes precede the development of nausea in motion sick susceptible subjects. Cerebral flow velocity in the middle cerebral artery (transcranial Doppler), blood pressure (Finapres) and end-tidal CO2 were measured while subjects were rotated on a centrifuge (250 degrees/sec). Following 5 min of rotation, subjects were translated 0.504 m off-center, creating a +lGx centripetal acceleration in the nasal-occipital plane. Ten subjects completed the protocol without symptoms while 5 developed nausea (4 while 6ff-center and 1 while rotating on-center). Prior to nausea, subjects had significant increases in blood pressure (+13plus or minus 3 mmHg, P less than 0.05) and cerebrovascular resistance (+46 plus or minus 17%, P less than 0.05) and decreases in cerebral flow velocity both in the second (-13 plus or minus 4%) and last minute (-22 plus or minus 5%) before symptoms (P less than 0.05). In comparison, controls demonstrated no change in blood pressure or cerebrovascular resistance in the last minute of off-center rotation and only a 7 plus or minus 2% decrease in cerebral flow velocity. All subjects had significant hypocapnia (-3.8 plus or minus 0.4 mmHg, P less than 0.05), however this hypocapnia could not fully explain the cerebral hypoperfusion associated with the development of nausea. These data indicate that reductions in cerebral blood flow precede the development of nausea. Further work is necessary to determine what role cerebral hypoperfusion plays in motion sickness and whether cerebral hypoperfusion can be used to predict the development of nausea in susceptible individuals.

Serrador, Jorge M.; Schlegel, Todd T.; Black, F. Owen; Wood, Scott J.

2004-01-01

404

Active stabilization to prevent surge in centrifugal compression systems  

NASA Technical Reports Server (NTRS)

This report documents an experimental and analytical study of the active stabilization of surge in a centrifugal engine. The aims of the research were to extend the operating range of a compressor as far as possible and to establish the theoretical framework for the active stabilization of surge from both an aerodynamic stability and a control theoretic perspective. In particular, much attention was paid to understanding the physical limitations of active stabilization and how they are influenced by control system design parameters. Previously developed linear models of actively stabilized compressors were extended to include such nonlinear phenomena as bounded actuation, bandwidth limits, and robustness criteria. This model was then used to systematically quantify the influence of sensor-actuator selection on system performance. Five different actuation schemes were considered along with four different sensors. Sensor-actuator choice was shown to have a profound effect on the performance of the stabilized compressor. The optimum choice was not unique, but rather shown to be a strong function of some of the non-dimensional parameters which characterize the compression system dynamics. Specifically, the utility of the concepts were shown to depend on the system compliance to inertia ratio ('B' parameter) and the local slope of the compressor speedline. In general, the most effective arrangements are ones in which the actuator is most closely coupled to the compressor, such as a close-coupled bleed valve inlet jet, rather than elsewhere in the flow train, such as a fuel flow modulator. The analytical model was used to explore the influence of control system bandwidth on control effectiveness. The relevant reference frequency was shown to be the compression system's Helmholtz frequency rather than the surge frequency. The analysis shows that control bandwidths of three to ten times the Helmholtz frequency are required for larger increases in the compressor flow range. This has important implications for implementation in gas turbine engines since the Helmholtz frequencies can be over 100 Hz, making actuator design extremely challenging.

Epstein, Alan H.; Greitzer, Edward M.; Simon, Jon S.; Valavani, Lena

1993-01-01

405

Collapse of the electron gas to two dimensions in density functional theory.  

PubMed

Local and semilocal density functional approximations for the exchange-correlation energy fail badly in the zero-thickness limit of a quasi-two-dimensional electron gas, where the density variation is rapid almost everywhere. Here we show that a fully nonlocal fifth-rung functional, the inhomogeneous Singwi-Tosi-Land-Sjölander (STLS) approach, which employs both occupied and unoccupied Kohn-Sham orbitals, recovers the true two-dimensional STLS limit and appears to be remarkably accurate for any thickness of the slab (and thus for the dimensional crossover). We also show that this good behavior is only partly due to the use of the full exact exchange energy. PMID:18764133

Constantin, Lucian A; Perdew, John P; Pitarke, J M

2008-07-01

406

Application of Gaussian random field theory to direct simulation of rarefied gas flow near rough surface  

NASA Astrophysics Data System (ADS)

Modified approach to the calculation of rarefied gas flow applying DSMC near a rough surface is developed and discussed. The roughness is simulated using random field - integrated Wiener process model. In earlier work, the near-free-molecular approach was applied to study external flows or internal flows in cylindrical and two-dimensional channels. Here, we extend and adapt these computational methods for the case of internal flows in channels and nozzles of variable cross-section. The transformation of the scattering function due to the roughness is characterized by the roughness operator. Simulating rough surface of the walls by Gaussian random field expressed as integrated Wiener process, we derive a representation of the roughness operator that can be applied in numerical DSMC methods as well as in analytical investigations.

Aksenova, Olga A.; Khalidov, Iskander A.,; Sviridovich, Victoria I.

2012-11-01

407

Relocation and repair of the National Geotechnical Centrifuge. Final report  

SciTech Connect

In January of 1984, the large geotechnical centrifuge located at NASA Ames Research Center, was in the first stages of operational checkout when the main thrust bearing of the large D.C. drive motor failed. After many months of investigation and proposals for repair of the facility, it became evident that it would be far more advantageous to the engineering community to remove those components of the centrifuge that were undamaged to the Davis campus and replace the drive system completely. The large centrifuge had cost over 2 million dollars to build, and it would have been irresponsible to simply scrap it. Recognizing this fact, funds were solicited and received from various sources, and Beam Engineering Inc. was contracted to design and construct the centrifuge at its new location. The University of California contributed a quarter of a million dollars and Tyndall Air Force Base, through Los Alamos National Laboratory, contributed $140,000. There were funds also contributed by LANL, LLNL, US Navy and NSF. The first stage in the phased development of the newly located centrifuge is nearing completion, which prompts the writing of this report. By the time that this report reaches the reader the first runs of the centrifuge will have been completed. The present report describes the present capability of the centrifuge and the plans for upgrading as time goes on. Several pilot studies were carried out. The experiments involved (1) the effects of nearby explosions on buried thin walled containers and (2) the advection and dispersion of toxic waste water through soils.

Cheney, J.A. [California Univ., Davis, CA (United States). Center for Geotechnical Modeling

1994-10-01

408

Analytic exchange integral for coupled cluster theory in the homogeneous electron gas  

NASA Astrophysics Data System (ADS)

A six-dimensional integral occurring in the description of the ground state of the homogeneous electron gas was calculated analytically. This formula, together with the one of a previous work [G.G. Hoffman, Phys. Rev. B 45 (1992) 8730], reduces from seven to one the dimension of the numerical integrations to be performed in the RPA+RPAEX approximation for the correlation energy [R.F. Bishop, K.H. Lührmann, Phys. Rev. B 26 (1982) 5523]. Program summaryTitle of program: qexm2em1 Catalogue identifier:ADXJ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADXJ_v1_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Distribution format: tar.gz Computers: Created using a PC, but can be run on UNIX machines Operating system under which the program has been tested: Linux Programming language used: Mathematica 4.0 (due to versions incompatibility the program does not work with more recent versions like Mathematica 5.1) Memory required to execute with typical data: 151 Mb Number of processors used: 1 Has this code been vectorized or parallelized? no No. of lines in distributed program, including test data, etc.: 13 415 Number of bytes in distributed program, including test data, etc.: 102 988 Nature of the physical problem: The program gives an analytical derivation of a six-dimensional exchange integral involved in the calculation of the correlation energy of the electron gas. Method of solution: Changes of variables were gradually introduced in order to decrease the dimensionality of the integral, and eventually an analytical expression was obtained. Restrictions on the complexity of the program: The present version of the program has been designed only for calculating only one integral. Though, the method can be used for other cylindrically-symmetric integrals. Typical running times: file formula.nb: less than 1 s; qexm2em1.nb: 02 mn 02 s; qexm2em1qinf2AA.nb: 09 mn 42 s; qexm2em1qinf2BB.nb: 08 mn 05 s; qexm2em1qinf2AB.nb: 00 mn 43 s; qexm2em1qsup2.nb: 23 mn 26 s on 1 GHz machine.

Gutlé, Claudine

2006-05-01

409

Kinetic theory of cavity cooling and self-organisation of a cold gas  

E-print Network

We study spatial self-organisation and dynamical phase-space compression of a dilute cold gas of laser-illuminated polarisable particles in an optical resonator. Deriving a non-linear Fokker--Planck equation for the particles' phase-space density allows us to treat arbitrarily large ensembles in the far-detuning limit and explicitly calculate friction forces, momentum diffusion and steady-state temperatures. In addition, we calculate the self-organisation threshold in a self-consistent analytic form. For a homogeneous ensemble below threshold the cooling rate for fixed laser power is largely independent of the particle number. Cooling leads to a $q$-Gaussian velocity distribution with a steady-state temperature determined by the cavity linewidth. Numerical simulations using large ensembles of particles confirm the analytical threshold condition for the appearance of an ordered state, where the particles are trapped in a periodic pattern and can be cooled to temperatures close to a single vibrational excitation.

Wolfgang Niedenzu; Tobias Grießer; Helmut Ritsch

2011-05-26

410

The NATA code: Theory and analysis, volume 1. [user manuals (computer programming) - gas dynamics, wind tunnels  

NASA Technical Reports Server (NTRS)

A computer program for calculating quasi-one-dimensional gas flow in axisymmetric and two-dimensional nozzles and rectangular channels is presented. Flow is assumed to start from a state of thermochemical equilibrium at a high temperature in an upstream reservoir. The program provides solutions based on frozen chemistry, chemical equilibrium, and nonequilibrium flow with finite reaction rates. Electronic nonequilibrium effects can be included using a two-temperature model. An approximate laminar boundary layer calculation is given for the shear and heat flux on the nozzle wall. Boundary layer displacement effects on the inviscid flow are considered also. Chemical equilibrium and transport property calculations are provided by subroutines. The code contains precoded thermochemical, chemical kinetic, and transport cross section data for high-temperature air, CO2-N2-Ar mixtures, helium, and argon. It provides calculations of the stagnation conditions on axisymmetric or two-dimensional models, and of the conditions on the flat surface of a blunt wedge. The primary purpose of the code is to describe the flow conditions and test conditions in electric arc heated wind tunnels.

Bade, W. L.; Yos, J. M.

1975-01-01

411

Study of Some Parameters of Modified Chaplygin Gas in Galileon Gravity Theory from Observational Perspective  

E-print Network

We have assumed the FRW model of the universe in Galileon gravity, which is filled with dark matter and Modified Chaplygin gas (MCG) type dark energy. We present the Hubble parameter in terms of some unknown parameters and observational parameters with the redshift $z$. Some cosmological parameters are reconstructed and plots are generated to study the nature of the model and its viability. It is seen that the model is perfectly consistent with the present cosmic acceleration. From \\textit{observed Hubble data (OHD) set or Stern data set} of 12 points, we have obtained the bounds of the arbitrary parameters ($A,B$) & ($A,C$) by minimizing the $\\chi^{2}$ test. Next due to joint analysis of \\textit{Stern+BAO} and \\textit{Stern+BAO+CMB} observations, we have also obtained the best fit values and the bounds of the parameters ($A,B$) & ($A,C$) by fixing some other parameters. The best-fit values and bounds of the parameters are obtained with 66%, 90% and 99% confidence levels for \\textit{Stern, Stern+BAO and Stern+BAO+CMB} joint analysis. Next we have also taken type Ia supernovae data set (union 2 data set with 557 data points). The distance modulus $\\mu(z)$ against redshift $z$ for our theoretical MCG model in Galileon gravity have been tested for the best fit values of the parameters and the observed \\textit{SNe Ia union 2 data} sample and from this, we have concluded that our model is in agreement with the union 2 sample data.

Chayan Ranjit; Prabir Rudra; Ujjal Debnath

2014-06-10

412

[The analytical setting of rotary speed of centrifuge rotor and centrifugation time in chemical, biochemical and microbiological practice].  

PubMed

The researchers happen to face with suspensions in their chemical, biochemical and microbiological practice. The suspensions are the disperse systems with solid dispersed phase and liquid dispersion medium and with dispersed phase particle size > 100 nm (10-7 m). Quite often the necessity occurs to separate solid particles from liquid. To use for this purpose the precipitation in gravitation field can make the process to progress too long. In this respect an effective mode is the precipitation in the field of centrifugal forces--the centrifugation. The rotary speed of centrifuge rotor and centrifugation time can be set analytically using regularities of general dynamics and hydrodynamics. To this effect, should be written and transformed the equation of First and Second Newton Laws for suspension particle being in the field of centrifugal forces and forces of resistance of liquid and vessel wall. The force of liquid resistance depends on particle motion condition in liquid. To determine the regimen the Archimedes and Reynolds numerical dimensionless criteria are to be applied. The article demonstrates the results of these transformations as analytical inverse ratio dependence of centrifugation time from rotary speed. The calculation of series of "rate-time" data permits to choose the optimal data pair on the assumption of centrifuge capacity and practical reasonability. The results of calculations are validated by actual experimental data hence the physical mathematical apparatus can be considered as effective one. The setting progress depends both from parameter (Reynolds criterion) and data series calculation. So, the most convenient way to apply this operation is the programming approach. The article proposes to use the program Microsoft Excel and VBA programming language for this purpose. The possibility to download the file from Internet to use it for fast solution is proposed. PMID:23097986

Zolotarev, K V

2012-08-01

413

Rules governing the classification of coal slurries for filtering centrifuges  

SciTech Connect

The feasibility of using filtering centrifuges for the cleaning of a coking-coal slurry is confirmed in principle, and regime operating parameters which ensure the production of a concentrate of conditioned quality are determined on the basis of results of experimental-industrial tests of a new procedure for this operation at the Neryungrinskaya Concentrating Mill. An equation is proposed for determination of solid carry-off in the centrifuge effluent, which completely satisfactorily (with a correlation coefficient of 0.7-0.8) describes the dependence of the parameter in question on the solid content in the centrifuge feed, and on its content of -0.2-mm material. It is noted that special investigations to determine the effect of the speed of the rotor and shape of the particles on the amount of solid carry-off in the centrifuge effluent are required for construction of a model describing the size reduction of solid-phase particles in the effluent during centrifuge filtration.

G.Y. Gol'berg; Y.B. Rubinshtein; S.A. Osadchii [Institute for Enrichment of Solid Fuel (IOTT), Moscow Oblast (Russian Federation)

2008-07-01

414

Centrifugal force reversal from the perspective of rigidly rotating observer  

E-print Network

In previous studies the dynamics of the relativistic particle moving along the rotating pipe was investigated. The simple gedanken experiment was considered. It was shown that at large enough velocities a centrifugal force acting on the bead changes its usual sign and attracts towards the rotation axis. The authors studied motion of the particle along the rotating straight pipe in the frame of the observer located in the center of rotation, also dynamics of centrifugally accelerated relativistic particle was studied in the laboratory frame. In the both cases it was shown that centrifugal force changes sign. Recently the problem was studied in the frame of stationary observers. It was argued that centrifugal acceleration reversal is not frame invariant effect. In the present paper we consider motion of particle along the rotating straight line in the frame of an arbitrary stationary observer located at certain distance form the center of rotation and rigidly rotating with constant angular velocity. It is shown that any stationary observer could detect reversal of centrifugal acceleration.

Giorgi Dalakishvili

2011-10-25

415

A fuzzy controlled three-phase centrifuge for waste separation  

SciTech Connect

The three-phase centrifuge technology discussed in this paper was developed by Neal Miller, president of Centech, Inc. The three-phase centrifuge is an excellent device for cleaning up oil field and refinery wastes which are typically composed of hydrocarbons, water, and solids. The technology is unique. It turns the waste into salable oil, reusable water, and landfill-able solids. No secondary waste is produced. The problem is that only the inventor can set up and run the equipment well enough to provide an optimal cleanup. Demand for this device has far exceeded a one man operation. There is now a need for several centrifuges to be operated at different locations at the same time. This has produced a demand for an intelligent control system, one that could replace a highly skilled operator, or at least supplement the skills of a less experienced operator. The control problem is ideally suited to fuzzy logic, since the centrifuge is a highly complicated machine operated entirely by the skill and experience of the operator. A fuzzy control system was designed for and used with the centrifuge.

Parkinson, W.J.; Smith, R.E. [Los Alamos National Lab., NM (United States); Miller, N. [Centech, Inc., Casper, WY (United States)

1998-02-01

416

Development of a Feeder for Uninterrupted Centrifugation Studies  

NASA Technical Reports Server (NTRS)

A specialized paste diet feeder was developed in support of a hypergravity (2G) centrifuge study. The centrifuge study was to be compared to a previously flown Russian Cosmos spaceflight so experimental parameters of the 14 day spaceflight had to be duplicated. In order to duplicate at hyper G an experiment that took place in weightlessness, all other conditions must be as identical as possible. Stopping the centrifuge to provide maintenance for the animals causes unacceptable changes in experimental research results. Thus the experimental protocol required the delivery of a designated amount of paste diet at regular intervals for a two week period without stopping the centrifuge. A centrifuge and a stationary control cage, each containing 10 laboratory rats, were fitted with feeders that were calibrated to provide 140 plus or minus 2g of paste diet every 6 hours. This paper describes development of the feeder design and results of its operation over the two week experiment. The design philosophy and details of the feeder system are provided with recommendations for future such devices.

Mulenburg, Gerald M.; Vasques, Marilyn F.; Gundo, Daniel P.; Griffith, Jon B.; Wade, Charles E. (Technical Monitor)

1994-01-01

417

Experimental investigation of the phenomenon of centrifuging of liquids  

SciTech Connect

Recently, the author has proposed a novel technique to produce hollow axisymmetric rapidly solidified materials by combining the principles of rapid solidification with that of centrifuge casting. The present work emerged as a prelude to this, with a view of gaining better insight into the intricacies of the phenomenon of centrifuging liquids and applying the understanding gained to produce rapidly solidified metallic seamless tubes. The phenomenon of centrifuging of liquids inside a horizontal tubular device rotated about its axis of symmetry has been experimentally investigated. Extensive experiments were conducted using a transparent apparatus which enabled visualization and photographic recording of the centrifuging phenomenon. Several interesting and useful qualitative observations not reported hitherto have been recorded. The effects of liquid volume (v[sub l]) density ([rho]), viscosity ([eta]), surface tension ([gamma]), and the apparatus geometry, viz., diameter (d) and length (l), on the critical speed (n) required to centrifuge 100 pct of the liquid were systematically studied using several inorganic liquids, the physical properties of which were also experimentally determined. The generated data over a wide range of variables have been shown to fit the following dimensionless correlation derived from first principles which is explained in the paper.

Babu, R.S. (Jindal Strips Limited, Haryana (India))

1993-06-01

418

Passively Shunted Piezoelectric Damping of Centrifugally-Loaded Plates  

NASA Technical Reports Server (NTRS)

Researchers at NASA Glenn Research Center have been investigating shunted piezoelectric circuits as potential damping treatments for turbomachinery rotor blades. This effort seeks to determine the effects of centrifugal loading on passively-shunted piezoelectric - damped plates. Passive shunt circuit parameters are optimized for the plate's third bending mode. Tests are performed both non-spinning and in the Dynamic Spin Facility to verify the analysis, and to determine the effectiveness of the damping under centrifugal loading. Results show that a resistive shunt circuit will reduce resonant vibration for this configuration. However, a tuned shunt circuit will be required to achieve the desired damping level. The analysis and testing address several issues with passive shunt circuit implementation in a rotating system, including piezoelectric material integrity under centrifugal loading, shunt circuit implementation, and tip mode damping.

Duffy, Kirsten P.; Provenza, Andrew J.; Trudell, Jeffrey J.; Min, James B.

2009-01-01

419

Space Station Centrifuge: A Requirement for Life Science Research  

NASA Technical Reports Server (NTRS)

A centrifuge with the largest diameter that can be accommodated on Space Station Freedom is required to conduct life science research in the microgravity environment of space. (This was one of the findings of a group of life scientists convened at the University of California, Davis, by Ames Research Center.) The centrifuge will be used as a research tool to understand how gravity affects biological processes; to provide an on-orbit one-g control; and to assess the efficacy of using artificial gravity to counteract the deleterious biological effect of space flight. The rationale for the recommendation and examples of using ground-based centrifugation for animal and plant acceleration studies are presented. Included are four appendixes and an extensive bibliography of hypergravity studies.

Smith, Arthur H.; Fuller, Charles A.; Johnson, Catherine C.; Winget, Charles M.

1992-01-01

420

A centrifuge CO{sub 2} pellet cleaning system  

SciTech Connect

Centrifuge-based cryogenic pellet accelerator technology, originally developed at Oak Ridge National Laboratory (ORNL) for the purpose of refueling fusion reactors with high-speed pellets of frozen deuterium/tritium, is now being developed as a method of cleaning without the use of conventional solvents. In these applications large quantities of pellets made of frozen CO{sub 2} or argon are accelerated in a high-speed rotor. The accelerated pellet stream is used to clean or etch surfaces. The advantage of this system is that the spent pellets and debris resulting from the cleaning process can be filtered leaving only the debris for disposal. This paper discusses the centrifuge CO{sub 2} pellet cleaning system, the physics model of the pellet impacting the surface, the centrifuge apparatus, and some initial cleaning and etching tests.

Foster, C.A.; Fisher, P.W.; Nelson, W.D.; Schechter, D.E.

1994-10-01

421

Centrifugal cosmological repulsive force in a homogeneous universe  

E-print Network

We study the dynamics of homogeneous isotropic three-dimensional worlds filled with radiation (3R-worlds). It is shown that the dynamics of these worlds with the additional fourth large-scale spatial dimension leads to an important effect. At 3R-worlds the forces of repulsion appear. The source of these forces is the thermal energy of the radiation that fills these worlds. In the four-dimensional space, these forces are centrifugal. They operate in an external for 3R-world spatial dimension and stretch it. In the three-dimensional comoving coordinate system the centrifugal forces shows themselves as forces of repulsion. Standard Einstein's equations do not describe these forces. Written generalized Einstein's equation describing the dynamics of a homogeneous isotropic universe, taking into consideration the centrifugal forces of repulsion. We propose a cosmological model of the universe, based on these equations. This model apply to explain the observation data.

A. V. Klimenko; V. A. Klimenko

2011-03-21

422

Centrifugally activated bearing for high-speed rotating machinery  

DOEpatents

A centrifugally activated bearing is disclosed. The bearing includes an annular member that extends laterally and radially from a central axis. A rotating member that rotates about the central axis relative to the annular member is also included. The rotating member has an interior chamber that surrounds the central axis and in which the annular member is suspended. Furthermore, the interior chamber has a concave shape for retaining a lubricant therein while the rotating member is at rest and for retaining a lubricant therein while the rotating member is rotating. The concave shape is such that while the rotating member is rotating a centrifugal force causes a lubricant to be forced away from the central axis to form a cylindrical surface having an axis collinear with the central axis. This centrifugally displaced lubricant provides restoring forces to counteract lateral displacement during operation.

Post, Richard F. (Walnut Creek, CA)

1994-01-01

423

Centrifugally activated bearing for high-speed rotating machinery  

DOEpatents

A centrifugally activated bearing is disclosed. The bearing includes an annular member that extends laterally and radially from a central axis. A rotating member that rotates about the central axis relative to the annular member is also included. The rotating member has an interior chamber that surrounds the central axis and in which the annular member is suspended. Furthermore, the interior chamber has a concave shape for retaining a lubricant therein while the rotating member is at rest and for retaining a lubricant therein while the rotating member is rotating. The concave shape is such that while the rotating member is rotating a centrifugal force causes a lubricant to be forced away from the central axis to form a cylindrical surface having an axis collinear with the central axis. This centrifugally displaced lubricant provides restoring forces to counteract lateral displacement during operation. 4 figures.

Post, R.F.

1994-02-15

424

Pneumomediastinum diagnosed by chest radiography after centrifuge training.  

PubMed

A retrospective review of the human centrifuge training database in the Republic of Singapore Air Force was carried out for the period 1995-2006. Six cases of pneumomediastinum were reported in aircrew trainees who underwent ab initio human centrifuge training. Only two of the six cases presented with chest discomfort with or without neck pain, with the rest being incidental findings picked up during routine medical examination. The diagnoses were confirmed by chest radiographs and computed tomography scans of the thorax. This is believed to be attributable to over-zealous or incorrect performance of the anti-G straining maneuver in trainees unaccustomed to a high G environment. Trainees subsequently underwent a structured weights training program and centrifuge training profiles were reviewed and revised to allow graduated G training. All affected trainees recovered uneventfully with conservative management, and were able to return to flying training. PMID:18457301

Gan, Wee Hoe; Lam, Pin Min; Chong, Chun Hon; Tan, Boon Chuan Benjamin; Fong, Kenneth Leopold; Tan, Hung Yong Richard

2008-04-01

425

Parametric performance evaluation of a hydraulic centrifugal pump  

NASA Astrophysics Data System (ADS)

Parametric study of a hydraulic centrifugal pump with backward curved blades has been performed numerically using three-dimensional Reynolds-averaged Navier-Stokes equations. The shear stress transport turbulence model was used for analysis of turbulence. The finite volume method and an unstructured grid system were used for the numerical solution. The optimal grid system in the computational domain was selected through a grid dependency test. Tested parameters were related to the geometry of the impeller and volute: seven variables defining the hub and shroud contours and the blades angle of impeller, and two variables defining the inlet width and expansion angle of volute. The effects of these parameters on the hydrodynamic performance of the centrifugal pump have been investigated. It was found that the centrifugal water pump with the twisted blades has the enhancing efficiency compared to the straight blades pump.

Heo, M. W.; Kim, K. Y.; Ma, S. B.; Yoo, I. S.; Choi, W. C.; Kim, J. H.; Choi, Y. S.

2014-12-01

426

Solvent-free cleaning using a centrifugal cryogenic pellet accelerator  

SciTech Connect

An advanced centrifuge that accelerates frozen CO{sub 2} pellets to high speeds for surface cleaning and paint removal is being developed at the Oak Ridge National Laboratory. The centrifuge-based accelerator was designed, fabricated, and tested under a program sponsored by the Warner Robins Air Logistics Center, Robins Air Force Base, Georgia. In comparison to the more conventional compressed air ``sandblast`` pellet accelerators, the centrifugal accelerator system can achieve higher pellet speeds, has precise speed control, and is more than ten times as energy efficient. Furthermore, the use of frozen CO{sub 2} pellets instead of conventional metal, plastic, sand, or other abrasive materials that remain solid at room temperature, minimizes the waste stream. This apparatus has been used to demonstrate cleaning of various surfaces, including removal of paint, oxide coatings, metal coatings, organic coatings, and oil and grease coatings from a variety of surfaces. The design and operation of the apparatus is discussed.

Haines, J.R.; Fisher, P.W.; Foster, C.A.

1995-06-01

427

Stationary patterns in centrifugally driven interfacial elastic fingering  

NASA Astrophysics Data System (ADS)

A vortex sheet formalism is used to search for equilibrium shapes in the centrifugally driven interfacial elastic fingering problem. We study the development of interfacial instabilities when a viscous fluid surrounded by another of smaller density flows in the confined environment of a rotating Hele-Shaw cell. The peculiarity of the situation is associated to the fact that, due to a chemical reaction, the two-fluid boundary becomes an elastic layer. The interplay between centrifugal and elastic forces leads to the formation of a rich variety of stationary shapes. Visually striking equilibrium morphologies are obtained from the numerical solution of a nonlinear differential equation for the interface curvature (the shape equation), determined by a zero vorticity condition. Classification of the various families of shapes is made via two dimensionless parameters: an effective bending rigidity (ratio of elastic to centrifugal effects) and a geometrical radius of gyration.

Carvalho, Gabriel D.; Gadêlha, Hermes; Miranda, José A.

2014-12-01

428

Centrifuge Techniques and Apparatus for Transport Experiments in Porous Media  

SciTech Connect

This paper describes experimental approaches and apparatus that we have developed to study solute and colloid transport in porous media using Idaho National Laboratory's 2-m radius centrifuge. The ex-perimental techniques include water flux scaling with applied acceleration at the top of the column and sub-atmospheric pressure control at the column base, automation of data collection, and remote experimental con-trol over the internet. These apparatus include a constant displacement piston pump, a custom designed liquid fraction collector based on switching valve technology, and modified moisture monitoring equipment. Suc-cessful development of these experimental techniques and equipment is illustrated through application to transport of a conservative tracer through unsaturated sand column, with centrifugal acceleration up to 40 gs. Development of such experimental equipment that can withstand high accelerations enhances the centrifuge technique to conduct highly controlled unsaturated solute/colloid transport experiments and allows in-flight liquid sample collection of the effluent.

Earl D. Mattson; Carl D. Paler; Robert W. Smith; Markus Flury

2010-06-01

429

Gas turbine engine  

SciTech Connect

The gas turbine engine includes a centrifugal fan having radial blades for receiving inlet air through inner entrance openings to spaces between adjacent blades. The air passes through outer exit openings from the spaces between the blades. Stationary inner and outer circumferential segments define closure members which successively eclipse the inner entrance and outer exit openings of the centrifugal fan blades when the fan rotates to position adjacent blades between the closure members. The closure members and space between the blades thus define closed combustion chambers. Fuel is injected and ignited so that continuous combustion takes place at constant volume, the exhaust gases escaping through the outer exit openings when rotation of the fan positions these openings beyond the outer closure members. This continuous combustion at constant volume provides for increased efficiency in the gas turbine engine over the brayton cycle constant pressure type turbine engine.

Gertz, D.C.

1980-12-30

430

75 FR 61461 - Central New York Oil and Gas Company, LLC; Notice of Availability of the Environmental Assessment...  

Federal Register 2010, 2011, 2012, 2013

...electric-driven 15,300-hp centrifugal compressor; Two 30-inch-diameter natural gas pipelines, each about 820 feet long, connecting the NS2 Compressor Station with Tennessee Gas Pipeline Company's (TGP)...

2010-10-05

431

The use of centrifugation to study early Drosophila embryogenesis  

NASA Technical Reports Server (NTRS)

By the end of 10th nuclear cycle, the somatic nuclei of the Drosophila embryo have migrated to the periphery of the egg. Centrifugation of embryos did not result in the displacement of these nuclei, since cytoskeletal elements anchor them to the cortex. But, mild centrifugal forces displace the centrally located, nascent yolk nuclei. If this increased sensitivity to hypergravity occurs before the beginning of nuclear differentiation during cycle 8, when the nascent yolk and somatic nuclei physically separate, then it would mark the earliest functional difference between these two lineages.

Abbott, M. K.; Spooner, B. S. (Principal Investigator)

1993-01-01

432

An Investigation of Backflow Phenomenon in Centrifugal Compressors  

NASA Technical Reports Server (NTRS)

Report presents the results of an investigation conducted to determine the nature and the extent of the reversal of flow, which occurs at the inlet of centrifugal compressors over a considerable portion of the operating range. Qualitative studies of this flow reversal were made by lampblack patterns taken on a mixed-flow-type impeller and by tuft studies made on a conventional centrifugal compressor. Quantitative studies were made on a compressor specially designed to enable survey of angularity of flow, static and total pressures, and temperatures to be taken very close to the impeller front housing.

Benser, William A; Moses, Jason J

1945-01-01

433

Secondary Containment Design for a High Speed Centrifuge  

SciTech Connect

Secondary containment for high speed rotating machinery, such as a centrifuge, is extremely important for operating personnel safety. Containment techniques can be very costly, ungainly and time consuming to construct. A novel containment concept is introduced which is fabricated out of modular sections of polycarbonate glazed into a Unistrut metal frame. A containment study for a high speed centrifuge is performed which includes the development of parameters for secondary containment design. The Unistrut/polycarbonate shield framing concept is presented including design details and proof testing procedures. The economical fabrication and modularity of the design indicates a usefulness for this shielding system in a wide variety of containment scenarios.

Snyder, K.W.

1999-03-01

434

Artificial gravity studies and design considerations for Space Station centrifuges  

NASA Technical Reports Server (NTRS)

The requirements to and capabilities of a Space Station biological facility centrifuge are discussed on the basis of an assessment of the objectives and subjects of future microgravity biological experiments. It is argued that the facility should be capable of both acute and extended chronic exposure of test subjects and biological materials to altered-g loading. In addition, the experimental approaches and equipment for microgravity studies on a Space Station are outlined. Finally, the engineering requirements of such a centrifuge are examined, with consideration of radial gravity gradients, size, and physical access to animals.

Halstead, T. W.; Brown, A. H.; Fuller, C. A.; Oyama, J.

1984-01-01

435

24. RW Meyer Sugar Mill: 18761889. Centrifugal inner basket, 1879. ...  

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

24. RW Meyer Sugar Mill: 1876-1889. Centrifugal inner basket, 1879. Manufacturer, unknown. Supplied by Honolulu Iron Works, Honolulu, Hawaii, 1879. View: After sugar was granulated and cooled it was dried and drained, completely separating the sugar crystals from the molasses, in the centrifugal. Revolving at 1200 rpm the sugar charge was forced outward with the molasses flying through the holes in the brass lining. Dried sugar was left behind in the inner basket and was dug out by hand. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

436

Apparatus and method for centrifugation and robotic manipulation of samples  

NASA Technical Reports Server (NTRS)

A device for centrifugation and robotic manipulation of specimen samples, including incubating eggs, and uses thereof are provided. The device may advantageously be used for the incubation of avian, reptilian or any type of vertebrate eggs. The apparatus comprises a mechanism for holding samples individually, rotating them individually, rotating them on a centrifuge collectively, injecting them individually with a fixative or other chemical reagent, and maintaining them at controlled temperature, relative humidity and atmospheric composition. The device is applicable to experiments involving entities other than eggs, such as invertebrate specimens, plants, microorganisms and molecular systems.

Vellinger, John C. (Inventor); Ormsby, Rachel A. (Inventor); Kennedy, David J. (Inventor); Thomas, Nathan A. (Inventor); Shulthise, Leo A. (Inventor); Kurk, Michael A. (Inventor); Metz, George W. (Inventor)

2007-01-01

437

Centrifugal inertia effects in two-phase face seal films  

NASA Technical Reports Server (NTRS)

A simplified, semianalytical model has been developed to analyze the effect of centrifugal inertia in two-phase face seals. The model is based on the assumption of isothermal flow through the seal, but at an elevated temperature, and takes into account heat transfer and boiling. Using this model, seal performance curves are obtained with water as the working fluid. It is shown that the centrifugal inertia of the fluid reduces the load-carrying capacity dramatically at high speeds and that operational instability exists under certain conditions. While an all-liquid seal may be starved at speeds higher than a 'critical' value, leakage always occurs under boiling conditions.

Basu, P.; Hughes, W. F.; Beeler, R. M.

1987-01-01

438

Water-gas shift reaction on oxide/Cu(111): Rational catalyst screening from density functional theory  

NASA Astrophysics Data System (ADS)

Developing improved catalysts based on a fundamental understanding of reaction mechanism has become one of the grand challenges in catalysis. A theoretical understanding and screening the metal-oxide composite catalysts for the water-gas shift (WGS) reaction is presented here. Density functional theory was employed to identify the key step for the WGS reaction on the Au, Cu-oxide catalysts, where the calculated reaction energy for water dissociation correlates well with the experimental measured WGS activity. Accordingly, the calculated reaction energy for water dissociation was used as the scaling descriptor to screen the inverse model catalysts, oxide/Cu(111), for the better WGS activity. Our calculations predict that the WGS activity increases in a sequence: Cu(111), ZnO/Cu(111) < TiO2/Cu(111), ZrO2/Cu(111) < MoO3/Cu(111). Our results imply that the high performances of Au, Cu-oxide nanocatalysts in the WGS reaction rely heavily on the direct participation of both oxide and metal sites. The degree that the oxide is reduced by Cu plays an important role in determining the WGS activity of oxide/Cu catalysts. The reducible oxide can be transformed from the fully oxidized form to the reduced form due to the interaction with Cu and, therefore, the transfer of electron density from Cu, which helps in releasing the bottleneck water dissociation and, therefore, facilitating the WGS reaction on copper.

Liu, Ping

2010-11-01

439

Exploring the discrepancies between experiment, theory, and simulation for the homogeneous gas-to-liquid nucleation of 1-pentanol  

NASA Astrophysics Data System (ADS)

Using an efficient Monte Carlo approach known as Aggregation-Volume-bias Monte Carlo with self-adaptive Umbrella Sampling and Histogram Reweighting (AVUS-HR), we obtained the nucleation free energy profile of 1-pentanol at various temperatures from 220 to 360 K. From these profiles, differences between the free energy barrier heights obtained from our simulations and those predicted by the classical nucleation theory (CNT) were calculated. Our results strongly support that the logarithm of the nucleation rate ratio between simulation (or experiment) and CNT increases almost linearly with the inverse temperature. Among the various factors that contribute to the discrepancy between simulation and CNT nucleation rates, the nonzero surface free energy of the monomer included in the CNT makes the largest contribution. On the molecular level, the simulations indicate that a gas-phase cluster of 1-pentanol molecules is relatively compact and can contain multiple hydrogen bonded aggregates of various sizes and that this aggregate size distribution depends strongly on temperature and also on the overall size of the cluster system.

Nellas, Ricky B.; Keasler, Samuel J.; Siepmann, J. Ilja; Chen, Bin

2010-04-01

440

Justification of statistical overlap theory in programmed temperature gas chromatography: thermodynamic origin of random distribution of retention times.  

PubMed

A specific distribution of compounds' standard-state changes of enthalpy and entropy between mobile and stationary phases in programmed temperature gas chromatography (PTGC) is shown to produce the Poisson distribution of retention times often postulated in statistical-overlap theory (SOT). A three-part model is proposed, in which the enthalpy change is Poisson distributed, the average entropy change depends on the enthalpy change, and the actual entropy change varies in a uniformly random manner about the average entropy change. To test the model, the entropy and enthalpy changes of 350 aliphatic and aromatic hydrocarbons in petroleum were calculated with commercial GC software. These changes are shown to follow the three-part model. The model then was used with Monte Carlo methods to mimic the enthalpy and entropy changes. The substitution of the mimicked enthalpy and entropy changes into an equation for the retention temperature in PTGC is shown to produce a Poisson distribution of retention times that is statistically significant. This finding establishes a scientific link between the thermodynamics governing retention in PTGC and the superficially ad hoc assumption of the Poisson retention time distribution in SOT. Similar thermodynamic distributions are found for flavors and fragrances and for tetrachlorodibenzo-p-dioxins and furans, which follow SOT based on the Poisson distribution, but not for polychloronaphthalenes, which do not follow that SOT. PMID:11101251

Davis, J M; Pompe, M; Samuel, C

2000-11-15

441

A 400-pellet feed system for the ORNL centrifuge pellet injector  

SciTech Connect

An improved and extended pellet fabrication and feed mechanism is being developed for the Oak Ridge National Laboratory (ORNL) centrifuge pellet injector that is presently installed on Tore Supra. This upgrade will extend the number of pellets available for a single-plasma discharge from 100 to 400. In addition, a new pusher and delivery system is expected to improve the performance of the device. As in the original system, deuterium ice is deposited from the gas phase on a liquid-helium-cooled rotating disk, forming a rim of solid deuterium. The rim of ice is machined to a parabolic profile from which pellets are pushed. In the new device, a stack of four ice rims are formed simultaneously, thereby increasing the capacity from 100 to 400 pellets. An improved method of ice formation has also been developed that produces clear ice. The pellet pusher and delivery system utilizes a four-axis, brushless dc servo system to precisely cut and deliver the pellets from the ice rim to the entrance of the centrifuge wheel. Pellets can be formed with sizes ranging from 2.5- to 4-mm diam at a rate of up to 8 per second. The operation of the injector is fully automated by a computer control system. The design and test results of the device are reported.

Foster, C.A.; Qualls, A.L.; Baylor, L.R.; Schechter, D.E.; Dyer, G.R.; Milora, S.L.

1993-11-01

442

21 CFR 862.2140 - Centrifugal chemistry analyzer for clinical use.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Centrifugal chemistry analyzer for clinical use. 862.2140...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical...Instruments § 862.2140 Centrifugal chemistry analyzer for clinical use. (a)...

2013-04-01

443

21 CFR 862.2140 - Centrifugal chemistry analyzer for clinical use.  

... 2014-04-01 false Centrifugal chemistry analyzer for clinical use. 862.2140...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical...Instruments § 862.2140 Centrifugal chemistry analyzer for clinical use. (a)...

2014-04-01

444

21 CFR 862.2140 - Centrifugal chemistry analyzer for clinical use.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 false Centrifugal chemistry analyzer for clinical use. 862.2140...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical...Instruments § 862.2140 Centrifugal chemistry analyzer for clinical use. (a)...

2012-04-01

445

21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.  

Code of Federal Regulations, 2011 CFR

...Drugs 8 2011-04-01 2011-04-01 false Blood bank centrifuge for in vitro diagnostic use. 864...DEVICES Products Used In Establishments That Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for...

2011-04-01

446

21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.  

...Drugs 8 2014-04-01 2014-04-01 false Blood bank centrifuge for in vitro diagnostic use. 864...DEVICES Products Used In Establishments That Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for...

2014-04-01

447

21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.  

Code of Federal Regulations, 2013 CFR

...Drugs 8 2013-04-01 2013-04-01 false Blood bank centrifuge for in vitro diagnostic use. 864...DEVICES Products Used In Establishments That Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for...

2013-04-01

448

21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.  

Code of Federal Regulations, 2012 CFR

...Drugs 8 2012-04-01 2012-04-01 false Blood bank centrifuge for in vitro diagnostic use. 864...DEVICES Products Used In Establishments That Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for...

2012-04-01

449

21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.  

Code of Federal Regulations, 2010 CFR

...Drugs 8 2010-04-01 2010-04-01 false Blood bank centrifuge for in vitro diagnostic use. 864...DEVICES Products Used In Establishments That Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for...

2010-04-01

450

Scales modified for use on board the human centrifuge in the MIT Man Vehicle Lab  

E-print Network

The MIT Man Vehicle Lab (MVL) is currently performing research on the effects of rotational artificial gravity on humans through the use of a short-radius centrifuge. The MVL centrifuge allows subjects to spin in the supine ...

Samuelson, Heather Marie

2006-01-01

451

Porous hydroxyapatite-polyhydroxybutyrate composites fabricated by a novel method via centrifugation  

E-print Network

centrifugation Michael M Porter1 , Steve Lee1 , Nuttapol Tanadchangsaeng2 , Matt J Jaremko2 , Jian Yu2 , Marc micro-/nano- particles into rigid HA scaffolds via centrifugation, followed by subsequent heating at 175

Meyers, Marc A.

452

Effects of centrifugation stress on pituitary-gonadal function in male rats  

NASA Technical Reports Server (NTRS)

The effects of centrifugation for various lengths of time on circulating levels of luteinizing hormone (LH) and testosterone in male rats were investigated. In a chronic 52-day experiment, centrifugation at 4.1 G significantly reduced LH and testosterone levels for the entire period. Centrifugation at 2.3 G had less effect inasmuch as LH levels were not significantly decreased and testosterone levels were significantly reduced only during the first few days of centrifugation. In more acute experiments, centrifugation at 4.1 G for 4 h resulted in reduced testosterone levels, whereas centrifugation for 15 min did not significantly alter the hormone levels. These results indicate that centrifugation can decrease circulating LH and testosterone levels if the gravitational force is of sufficient magnitude and is maintained for a period of hours. Chronic centrifugation may also inhibit the acute excitatory response of LH to handling and ether stress.

Gray, G. D.; Smith, E. R.; Damassa, D. A.; Davidson, J. M.

1980-01-01

453

Advanced Remote Maintenance Design for Pilot-Scale Centrifugal Contactors  

SciTech Connect

Advanced designs of used nuclear fuel recycling processes and radioactive waste treatment processes are expected to include more ambitious goals for aqueous based separations including; higher separations efficiency, high-level waste minimization, and a greater focus on continuous processes to minimize cost and footprint. Therefore, annular centrifugal contactors are destined to play a more important role for such future processing schemes. Pilot-scale testing will be an integral part of development of many of these processes. An advanced design for remote maintenance of pilot-scale centrifugal contactors has been developed and a prototype module fabricated and tested for a commercially available pilot-scale centrifugal contactor (CINC V-02, 5-cm rotor diameter). Advanced design features include air actuated clamps for holding the motor-rotor assembly in place, an integral electrical connection, upper flange o-rings, a welded bottom plate, a lifting bale, and guide pins. These design features will allow for rapid replacement of the motor rotor assembly, which can be accomplished while maintaining process equilibrium. Hydraulic testing of a three-stage prototype unit was also performed to verify that design changes did not impact performance of the centrifugal contactors. Details of the pilot-scale remote maintenance design, results of testing in a remote mockup test facility, and results of hydraulic testing of the advanced design are provided.

Jack Law; David Meikrantz; Troy Garn; Lawrence Macaluso

2011-02-01

454

Fluid dynamic interaction between water hammer and centrifugal pumps  

Microsoft Academic Search

Centrifugal pumps generate in piping systems noticeable pressure pulsations. In this paper the dynamic interaction between water hammer and pressure pulsations is presented. The experimental investigations were performed at a piping system with nominal diameter DN 100 (respectively NPS 4) and 75m total length, built at the Institute for Process Technology and Machinery. Different measurements at this testing facility show

A. Ismaier; E. Schlücker

2009-01-01

455

Experimental Analysis on Centrifugal Chillersunder Cycling Operation Mode  

NASA Astrophysics Data System (ADS)

Duty cycling of centrifugal chillers has been considered an effective method for demand side management. Full scale experiments were performed to identify that unloading was a necessary step so that excessive mechanical wear would not occur due to cycling operation. On the other hand, reciprocating and screw compressors can adapt to cycling operation successfully.

Mu-Min, Ting

456

SEPARATION OF METALS IN WASTEWATER SLUDGE BY CENTRIFUGAL CLASSIFICATION  

EPA Science Inventory

Municipal wastewater sludges frequently contain undesirably high concentrations of heavy metals and/or organic pollutants which interfere with beneficial use of sludge on farmland and with some disposal practices such as ocean disposal. Centrifugal classification is a low-cost pr...

457

Quasi-steady centrifuge method for unsaturated hydraulic properties  

USGS Publications Warehouse

[1] We have developed the quasi-steady centrifuge (QSC) method as a variation of the steady state centrifuge method that can be implemented simply and inexpensively with greater versatility in terms of sample size and other features. It achieves these advantages by somewhat relaxing the criterion for steadiness of flow through the sample. This compromise entails an increase in measurement uncertainty but to a degree that is tolerable in most applications. We have tested this new approach with an easily constructed apparatus to establish a quasi-steady flow of water in unsaturated porous rock samples spinning in a centrifuge, obtaining measurements of unsaturated hydraulic conductivity and water retention that agree with results of other methods. The QSC method is adaptable to essentially any centrifuge suitable for hydrogeologic applications, over a wide range of sizes and operating speeds. The simplified apparatus and greater adaptability of this method expands the potential for exploring situations that are common in nature but have been the subject of few laboratory investigations. Copyright 2005 by the American Geophysical Union.

Caputo, M.C.; Nimmo, J.R.

2005-01-01

458

Apollo 8 prime crew stand beside gondola for centrifuge training  

NASA Technical Reports Server (NTRS)

The Apollo 8 prime crew stands beside the gondola in bldg 29 after suiting up for centrifuge training in the Manned Spacecraft Center's (MSC) Flight Acceleration Facility. Left to right, are Astronauts William A. Anders, lunar module pilot; James A. Lovell Jr.,command module pilot; and Frank Borman, commander.

1968-01-01

459

Threshold experiments performed in a slow rotating centrifuge microscope (NIZEMI)  

NASA Astrophysics Data System (ADS)

The slow rotating centrifuge with microscope (NIZEMI) makes possible optical investigations of samples under variable acceleration levels. The present design of NIZEMI for accommodation on board SPACELAB during the International Microgravity Mission IML-2 in spring 1994 is presented. Experiment interfaces will be discussed. One material science threshold experiment for crystal growth under varying g-levels will be explained.

Behrle, R.; Leonartz, K.; Joop, O.; Ecker, A.; Kern, P.

1992-01-01

460

Propeller Vibrations and the Effect of the Centrifugal Force  

NASA Technical Reports Server (NTRS)

A method has been devised for determining the frequencies of the various modes of a stationary propeller and the associated crankshaft. A method has also been devised to obtain the effect of the centrifugal force on a revolving propeller by use of a flexible model.

Theodorsen, T

1935-01-01

461

Return to Flying Duties Following Centrifuge or Vibration Exposures  

NASA Technical Reports Server (NTRS)

Introduction: In an effort to determine the human performance limits for vibration in spacecraft being developed by NASA, astronauts were evaluated during a simulated launch profile in a centrifuge/vibration environment and separate vibration-only simulation. Current USAF and Army standards for return to flight following centrifuge exposures require 12-24 hours to pass before a crewmember may return to flying duties. There are no standards on vibration exposures and return to flying duties. Based on direct observation and provocative neurological testing of the astronauts, a new standard for return to flying duties following centrifuge and/or vibration exposures was established. Methods: 13 astronaut participants were exposed to simulated launch profiles in a + 3.5 Gx bias centrifuge/vibration environment and separately on a vibration table at the NASA-Ames Research Center. Each subject had complete neurological evaluations pre- and post-exposure for the centrifuge/vibration runs with the NASA neurological function rating scale (NFRS). Subjects who participated in the vibration-only exposures had video oculography performed with provocative maneuvers in addition to the NFRS. NFRS evaluations occurred immediately following each exposure and at 1 hour post-run. Astronauts who remained symptomatic at 1 hour had repeat NFRS performed at 1 hour intervals until the crewmember was asymptomatic. Results: Astronauts in the centrifuge/vibration study averaged a 3-5 point increase in NFRS scores immediately following exposure but returned to baseline 3 hours post-run. Subjects exposed to the vibration-only simulation had a 1-3 point increase following exposure and returned to baseline within 1-2 hours. Pre- and post- vibration exposure video oculography did not reveal any persistent ocular findings with provocative testing 1 hour post-exposure. Discussion: Based on direct observations and objective measurement of neurological function in astronauts following simulated launch profiles, asymptomatic individuals are allowed to return to flying duties within 3 hours following centrifuge/vibration and 2 hours after vibration-only exposures.

Scheuring, Richard A.; Clarke, Jonathan; Jones, Jeffrey A.

2009-01-01

462

MODELING AEROSOL FORMATION FROM ALPHA-PINENE + NOX IN THE PRESENCE OF NATURAL SUNLIGHT USING GAS PHASE KINETICS AND GAS-PARTICLE PARTITIONING THEORY. (R826771)  

EPA Science Inventory

A kinetic mechanism was used to link and model the gas-phase reactions and aerosol accumulation resulting from -pinene reactions in the presence of sunlight, ozone (O3), and oxides of nitrogen (NO ...

463

Centrifuge impact cratering experiments: Scaling laws for non-porous targets  

NASA Technical Reports Server (NTRS)

A geotechnical centrifuge was used to investigate large body impacts onto planetary surfaces. At elevated gravity, it is possible to match various dimensionless similarity parameters which were shown to govern large scale impacts. Observations of crater growth and target flow fields have provided detailed and critical tests of a complete and unified scaling theory for impact cratering. Scaling estimates were determined for nonporous targets. Scaling estimates for large scale cratering in rock proposed previously by others have assumed that the crater radius is proportional to powers of the impactor energy and gravity, with no additional dependence on impact velocity. The size scaling laws determined from ongoing centrifuge experiments differ from earlier ones in three respects. First, a distinct dependence of impact velocity is recognized, even for constant impactor energy. Second, the present energy exponent for low porosity targets, like competent rock, is lower than earlier estimates. Third, the gravity exponent is recognized here as being related to both the energy and the velocity exponents.

Schmidt, Robert M.

1987-01-01

464

Hartree-Fock theory of the inhomogeneous electron gas at a jellium metal surface: Rigorous upper bounds to the surface energy and accurate work functions  

Microsoft Academic Search

The inhomogeneous electron gas at a jellium metal surface is studied in the Hartree-Fock approximation by Kohn-Sham density functional theory. Rigorous upper bounds to the surface energy are derived by application of the Rayleigh-Ritz variational principle for the energy, the surface kinetic, electrostatic, and nonlocal exchange energy functionals being determined exactly for the accurate linear-potential model electronic wave functions. The

V. Sahni; C. Q. Ma

1980-01-01

465

Screen bowl centrifuge: a high-efficiency particle size separator  

SciTech Connect

Over the years, screen bowl centrifuges have been widely used for dewatering fine coal in coal preparation plants in the United States and elsewhere. It is generally recognized in the engineering and scientific communities that screen bowl centrifuges provide some degree of particle size separation while dewatering fine coal in a common application. However, the extent of differential partitioning of coarse and fine particles achievable by a screen bowl centrifuge has not been systematically studied in the past. The present investigation was aimed at conducting a parametric study using a statistically designed experimental program to better understand and optimize the size classification performance of a screen bowl centrifuge. A continuously operating screen bowl centrifuge having a bowl diameter of 0.5 m was used for this study at the Illinois Coal Development Park. Three key operating parameters, i.e., feed flow rate, feed solid content and pool depth, were varied to conduct a total of 17 experiments using a three-level factorial test matrix. Some of the best size separation performances achieved in this study may be described as having an imperfection value of 0.13 at an effective separation size (d(50c)) of 38 mu m and an imperfection value of 0.27 at an effective separation size (d(50c)) of 2.8 mu m. Due to an effective separation of ultrafine high ash materials, the ash content of the screen bowl feed was reduced from 22.3% to a minimum of 8.84% with a combustible recovery of 84.1% and an ash rejection of 71.6%. A higher combustible recovery of 92.1% was achieved at a product ash content of 12.5% with a d(50c) of 2.8 mu m and imperfection of 0.27.

Mohanty, M.K.; Zhang, B.; Khanna, N.; Palit, A.; Dube, B. [South Illinois University, Carbondale, IL (United States). Dept. for Mining & Mineral Resources Engineering

2008-05-15

466

Performance and Dynamic Stability of General-Path Centrifugal Pendulum Vibration  

E-print Network

Performance and Dynamic Stability of General-Path Centrifugal Pendulum Vibration Absorbers A. S 48824, USA RUNNING HEADLINE: GENERAL PATH CPVAS. #12;Abstract Centrifugal pendulum vibration absorbers of multiple, identical centrifugal pendulum vibration absorbers that have general paths. The study is carried

Shaw, Steven W.

467

Centrifugal Separation of Antiprotons and Electrons G. Gabrielse,1,* W. S. Kolthammer,1  

E-print Network

Centrifugal Separation of Antiprotons and Electrons G. Gabrielse,1,* W. S. Kolthammer,1 R. Mc November 2010) Centrifugal separation of antiprotons and electrons is observed, the first antiprotons for precision tests of fundamental symmetries and for cold antihydrogen studies. The centrifugal

Richerme, Phil

468

The effects of centrifugation, various synthetic media and temperature on the motility and vitality  

E-print Network

The effects of centrifugation, various synthetic media and temperature on the motility and vitality staining. Centrifugation of semen (diluted 1 : 1 with Tyrode) at forces of 500, 800, 1 800 and 2 500 x g (Al), dilution, centrifugation and influence of incubation temperature must also be evaluated

Paris-Sud XI, Université de

469

Centrifuge Permeameter for Unsaturated Soils. I: Theoretical Basis and Experimental Developments  

E-print Network

Centrifuge Permeameter for Unsaturated Soils. I: Theoretical Basis and Experimental Developments Jorge G. Zornberg, M.ASCE1 ; and John S. McCartney, A.M.ASCE2 Abstract: A new centrifuge permeameter the centrifuge permeame- ter for concurrent determination of the soil-water retention curve SWRC and hydraulic

Zornberg, Jorge G.

470

Cycle-powered short radius (1.9M) centrifuge: exercise vs. passive acceleration  

NASA Technical Reports Server (NTRS)

A human-powered short-arm centrifuge is described. This centrifuge could be used during spaceflight to provide +Gz acceleration while subjects performed exercise, thus supplying two forms of weightlessness countermeasures. Results from a study of cardiovascular responses while using the centrifuge are presented.

Greenleaf, J. E.; Gundo, D. P.; Watenpaugh, D. E.; Mulenburg, G. M.; Marchman, N.; Looft-Wilson, R.; Hargens, A. R.

1996-01-01

471

DETERMINATION OF THE SWELL-STRESS CURVE OF AN EXPANSIVE SOIL USING CENTRIFUGE TECHNOLOGY  

E-print Network

DETERMINATION OF THE SWELL-STRESS CURVE OF AN EXPANSIVE SOIL USING CENTRIFUGE TECHNOLOGY project was conducted on the use of centrifuge technology to characterize the expansive properties of a soil sample in the centrifuge. This paper focuses on the analysis of testing results, specifically how

Zornberg, Jorge G.

472

Centrifugal Shape Sorting of Faceted Gold Nanoparticles Using an Atomic Plane-Selective Surfactant  

E-print Network

Centrifugal Shape Sorting of Faceted Gold Nanoparticles Using an Atomic Plane-Selective Surfactant control or postsynthetic processing that relies on centrifugal sedimentation-based sorting schemes whereNPs possessing different shapes that would otherwise be virtually indistinguishable during centrifugal

Gao, Hongjun

473

Absolute H Emission Measurement System for the Maryland Centrifugal eXperiment  

E-print Network

Absolute H Emission Measurement System for the Maryland Centrifugal eXperiment Ryan Clary April 22 developed and implemented at the Maryland Centrifugal eXperiment (MCX). The primary goal of this system Introduction The Maryland Centrifugal eXperiment (MCX) is a rotating-plasma mirror machine. The purpose

Anlage, Steven

474

Critique of the Centrifugal Effect in the Hydrogen Atom Frank Rioux  

E-print Network

Critique of the Centrifugal Effect in the Hydrogen Atom Frank Rioux Some quantum textbooks invoke with involves the middle term in the Hamiltonian given above. Some authors call it the centrifugal potential the effective potential energy. In support of this maneuver they invoke the idea of centrifugal force, which

Rioux, Frank

475

Concentrating Viruses with Centrifugal Ultrafiltration Devices Jennifer Brum, Tucson Marine Phage Lab  

E-print Network

Concentrating Viruses with Centrifugal Ultrafiltration Devices Jennifer Brum, Tucson Marine Phage an Amicon or Nanosep centrifugal ultrafiltration device. We use Amicons to concentrate medium volumes - centrifuge capable of 1000 x g - vortexer - parafilm Amicon Protocol: 1) Add your sample to the upper

Sullivan, Matthew B.

476

Expression des constantes de distorsion centrifuge des hexafluorures en fonction des frquences harmoniques.  

E-print Network

L-55 Expression des constantes de distorsion centrifuge des hexafluorures en fonction des de distorsion centrifuge des molécules XY6 en fonc- tion des fréquences harmoniques ; l for the centrifugal distortion constants as a function of harmonic frequencies ; application is made to SF6 and UF6. 4

Paris-Sud XI, Université de

477

Impact of sludge mechanical behaviour on spatial distribution parameters obtained with centrifugal spreader  

E-print Network

with centrifugal spreader P. Héritier, J-C. Roux, E. Dieudé-Fauvel* Cemagref, Domaine des Palaquins, 03150 materials rheological behaviour on spatial distribution parameters obtained with centrifugal spreader, i, centrifugal spreading, radial and angular distributions. 1. Introduction Wastewater treatment plants produce

Paris-Sud XI, Université de

478

Effect of the centrifugal force on domain chaos in Rayleigh-Bnard convection Nathan Becker,1,  

E-print Network

Effect of the centrifugal force on domain chaos in Rayleigh-Bénard convection Nathan Becker,1, * J and simulations from a variety of sample sizes indicated that the centrifugal force significantly affects and simulation we show that the centrifugal force is responsible for the radial rolls. Furthermore, simulations

Ahlers, Guenter

479

WAVE-DRIVEN ROTATION IN CENTRIFUGAL MIRRORS Abraham J. Fetterman and Nathaniel J. Fisch  

E-print Network

WAVE-DRIVEN ROTATION IN CENTRIFUGAL MIRRORS Abraham J. Fetterman and Nathaniel J. Fisch Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA Centrifugal mirrors use input. By eliminating the need for electrodes, this opens new op- portunities for centrifugal traps. I

480

THE CENTRIFUGE PERMEAMETER FOR UNSATURATED SOILS (CPUS) By: John McCartney1  

E-print Network

THE CENTRIFUGE PERMEAMETER FOR UNSATURATED SOILS (CPUS) By: John McCartney1 and Jorge Zornberg, Advisor2 Abstract: This paper describes the development of a new centrifuge permeameter capable inflow rates (0.1 ml/min) within a rotating centrifuge environment, capable of imposing an acceleration

Zornberg, Jorge G.

481

Constant centrifugal potential approximation for atom-diatom chemical reaction dynamics  

E-print Network

Constant centrifugal potential approximation for atom-diatom chemical reaction dynamics Kengo,Myodaiji, Okazaki 444. Japan (Received 28 September 1993; accepted 8 December 1993) The constant centrifugal of such practically useful approxima- tions the constant centrifugal potential approximation (CCPA) (or the energy

Takada, Shoji

482

Instabilities due a vortex at a density interface: gravitational and centrifugal effects  

E-print Network

Instabilities due a vortex at a density interface: gravitational and centrifugal effects Harish N showed recently that the flow is subject to centrifugal Rayleigh-Taylor and spiral Kelvin for example [5]). In the absence of gravity, centrifugal forces are predominant, and we showed recently [4

Dixit, Harish

483

Centrifugal fertiliser spreading: velocity and mass flow distribution measurement by image processing  

E-print Network

1 Centrifugal fertiliser spreading: velocity and mass flow distribution measurement by image to measure the velocity and the mass flow distribution of fertiliser granules spread by a centrifugal device from a compartmented collection ring. Keywords Centrifugal fertiliser spreading, velocity, mass flow

Paris-Sud XI, Université de

484

An optimization method for the reduction of fertilization errors with centrifugal  

E-print Network

An optimization method for the reduction of fertilization errors with centrifugal applicators Jonas This paper discusses an optimization method for the spreading performed by centrifugal spreaders in order Lagrangian, centrifugal spread- ers. hal-00678112,version1-12Mar2012 #12;1 INTRODUCTION 2 1 Introduction

Boyer, Edmond

485

Title of dissertation: H & NEUTRAL DENSITY SCALING IN THE MARYLAND CENTRIFUGAL EXPERI-  

E-print Network

ABSTRACT Title of dissertation: H & NEUTRAL DENSITY SCALING IN THE MARYLAND CENTRIFUGAL EXPERI Department of Physics The Maryland Centrifugal eXperiment (MCX) is a hydrogen plasma confinement experiment with a rotating mirror magnetic configuration. This experiment was de- signed to test the concepts of centrifugal

Anlage, Steven

486

Egg beater as centrifuge: isolating human blood plasma from whole blood in resource-poor settings  

E-print Network

Egg beater as centrifuge: isolating human blood plasma from whole blood in resource-poor settings809830c This paper demonstrates that a hand-powered egg beater can be modified to serve as a centrifuge plasma from whole blood, and obtaining plasma typically requires electrically-powered centrifuges, which

Prentiss, Mara

487

Drum Centrifuge Model Tests Comparing the Performance of Spudcans and Caissons in Kaolin Clay  

E-print Network

Drum Centrifuge Model Tests Comparing the Performance of Spudcans and Caissons in Kaolin Clay by M@eng.ox.ac.uk http://www-civil.eng.ox.ac.uk/ #12;Cassidy, M.J. and Byrne, B.W. 1 Drum Centrifuge Model Tests established drum centrifuge facility located at the University of Western Australia and were carried out

Byrne, Byron

488

Paper No. 9.06 1 NEWMARKIAN ANALYSIS OF LIQUEFIED FLOW IN CENTRIFUGE MODEL  

E-print Network

Paper No. 9.06 1 NEWMARKIAN ANALYSIS OF LIQUEFIED FLOW IN CENTRIFUGE MODEL EARTHQUAKES S.K. Haigh S-pressure history either predicted using a suitable constitutive model, or measured during a centrifuge or shaking displacements using this procedure and displacements measured in centrifuge model tests with the same pore

Haigh, Stuart

489

Computer Methods and Programs in Biomedicine 24 (1987) 179-188 Computer-assisted centrifugal elutriation.  

E-print Network

Computer Methods and Programs in Biomedicine 24 (1987) 179-188 Computer-assisted centrifugal separations by centrifugal elutriation, we constructed an on-line computer-controlled multiparametric light-controlled elutriation. Cell separation; Centrifugal elutriation; Multiparametric light-scatter analysis; Stand

490

ON CENTRIFUGAL SETTLING OF POLYDISPERSE SUSPENSIONS WITH A CONTINUOUS PARTICLE SIZE DISTRIBUTION  

E-print Network

ON CENTRIFUGAL SETTLING OF POLYDISPERSE SUSPENSIONS WITH A CONTINUOUS PARTICLE SIZE DISTRIBUTION@ucn.cl ABSTRACT Gravity or centrifugal sedimentation of polydisperse suspensions with a continuous particle size is extended to settling in a rotating tube or basket centrifuge. Numerical simulations are presented

Bürger, Raimund

491

Gap size effects on centrifugally and rotationally driven instabilities innocent MutabazP and Christiane Normand  

E-print Network

Gap size effects on centrifugally and rotationally driven instabilities innocent Mutabaz 1991) The rotation effects on centrifugally driven instabilities in curved channel flow with a finite these instabilities are due to the curvature of streamlines in- ducing a centrifugal force which unbalances the radial

Wesfreid, José Eduardo

492

Validity of the centrifuge method for determining the water retention properties of tropical soils  

E-print Network

1 Validity of the centrifuge method for determining the water retention properties of tropical.Bruand@univ-orleans.fr (A. Bruand) ABSTRACT This study compared the centrifuge and pressure plate methods with appropriate retention recorded by using the pressure plate and centrifuge methods. The results showed good agreement (R2

Paris-Sud XI, Université de

493

IEEE Visualization Contest 2011 Visualizing Unsteady Vortical Behavior of a Centrifugal Pump  

E-print Network

IEEE Visualization Contest 2011 Visualizing Unsteady Vortical Behavior of a Centrifugal Pump number 226042. em eg We present our results analyzing a centrifugal pump as a part of the IEEE Visualization Contest 2011. The given data set represents a high resolution simulation of a centrifugal pump

494

Integral methods for flow in a conical centrifuge Digby D. Symons n  

E-print Network

Integral methods for flow in a conical centrifuge Digby D. Symons n University of Cambridge Available online 13 April 2011 Keywords:: Centrifugation Films Fluid mechanics Laminar flow Mathematical of a variety of materials within an industrial conical centrifuge. By assuming a through-thickness velocity

Crilly, Nathan

495

On the effect of centrifugal stretching on the rotational partition function of an asymmetric top  

E-print Network

On the effect of centrifugal stretching on the rotational partition function of an asymmetric top;accepted13August 1991) Correction terms (up to third order in temperature) for the effectof centrifugal'sasymptotic expansionfor the rigid rotor and the centrifugal correction factor derivedin the presentwork. Numerical

Martin, Jan M.L.

496

40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...  

Code of Federal Regulations, 2010 CFR

...system that moves heated air through the mold 27 lb/ton. 8. Centrifugal casting...system that moves heated air through the mold 21 lb/ton. 7. Centrifugal casting...system that moves ambient air through the mold 2 lb/ton. 8. Centrifugal...

2010-07-01

497

40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...  

Code of Federal Regulations, 2011 CFR

...system that moves heated air through the mold 27 lb/ton. 8. Centrifugal casting...system that moves heated air through the mold 21 lb/ton. 7. Centrifugal casting...system that moves ambient air through the mold 2 lb/ton. 8. Centrifugal...

2011-07-01

498

40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...  

Code of Federal Regulations, 2012 CFR

...system that moves heated air through the mold 27 lb/ton. 8. Centrifugal casting...system that moves heated air through the mold 21 lb/ton. 7. Centrifugal casting...system that moves ambient air through the mold 2 lb/ton. 8. Centrifugal...

2012-07-01

499

40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...  

Code of Federal Regulations, 2013 CFR

...system that moves heated air through the mold 27 lb/ton. 8. Centrifugal casting...system that moves heated air through the mold 21 lb/ton. 7. Centrifugal casting...system that moves ambient air through the mold 2 lb/ton. 8. Centrifugal...

2013-07-01

500

21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Automated cell-washing centrifuge for immuno-hematology...Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for...

2012-04-01