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1

The Gas Centrifuge  

Microsoft Academic Search

The gas centrifuge is expected to play a large role in the 30% increase of the U.S. uranium-enrichment capacity required by President Carter's antiproliferation policy. The basis for the gaseous centrifugation process is described: axial countercurrent circulation, Ekman suction, scoop, separative power, etc. The economics of the process are next discussed. Connections between units must be arranged in a configuration

Donald R. Olander

1978-01-01

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

Gas centrifuge with driving motor  

Microsoft Academic Search

A centrifuge for separating gaseous constituents of different masses consists of: a vertical tubular rotor; means for introducing a gas mixture of different masses into the rotor and means for removing at least one of the gas components from the rotor; a first bearing means supporing the rotor at one end; a support; a damping bearing mounted on the support;

Dancy; W. H. Jr

1976-01-01

4

Gas centrifuge with driving motor  

Microsoft Academic Search

1. A centrifuge for separating gaseous constituents of different masses comprising a vertical tubular rotor, means for introducing a gas mixture of different masses into said rotor and means for removing at least one of the gas components from the rotor, a first bearing means supporting said rotor at one end for rotational movement, a support, a damping bearing mounted

Dancy; William H

1976-01-01

5

Uranium Enrichment by Gas Centrifuge.  

National Technical Information Service (NTIS)

After recalling the physical principles and the techniques of centrifuge enrichment the report describes the centrifuge enrichment programs of the various countries concerned and compares this technology with other enrichment technologies like gaseous dif...

I. D. Heriot

1988-01-01

6

Modern gas centrifuge and rarefied-gas dynamics  

Microsoft Academic Search

The modern gas centrifuge appears to be the preferred method for the enrichment of the isotopes of uranium on a commercial scale. Centrifuge problems involving rarefield gas dynamics considerations are discussed.

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

1981-01-01

7

Safety aspects of gas centrifuge enrichment plants  

Microsoft Academic Search

Uranium enrichment by gas centrifuge is a commercially proven, viable technology. Gas centrifuge enrichment plant operations pose hazards that are also found in other industries as well as unique hazards as a result of processing and handling uranium hexafluoride and the handling of enriched uranium. Hazards also found in other industries included those posed by the use of high-speed rotating

1987-01-01

8

Analysis of Gas Flow in a Centrifuge.  

National Technical Information Service (NTIS)

Onsager's sixth order, elliptic, partial differential equation with Ekman boundary layer suction describing linearized flow in a gas centrifuge has been rederived from the linearized compressible Navier-Stokes equations by asymptotic methods. A Galerkin w...

M. H. Berger

1982-01-01

9

Safety aspects of gas centrifuge enrichment plants  

SciTech Connect

Uranium enrichment by gas centrifuge is a commercially proven, viable technology. Gas centrifuge enrichment plant operations pose hazards that are also found in other industries as well as unique hazards as a result of processing and handling uranium hexafluoride and the handling of enriched uranium. Hazards also found in other industries included those posed by the use of high-speed rotating equipment and equipment handling by use of heavy-duty cranes. Hazards from high-speed rotating equipment are associated with the operation of the gas centrifuges themselves and with the operation of the uranium hexafluoride compressors in the tail withdrawal system. These and related hazards are discussed. It is included that commercial gas centrifuge enrichment plants have been designed to operate safely.

Hansen, A.H.

1987-01-01

10

Practical Computation of Multidimensional Thermal Flows in a Gas Centrifuge.  

National Technical Information Service (NTIS)

A finite-element theory is derived for Onsager's two-dimensional equation approximating the steady, viscous, gas motion in a high-speed centrifuge. A new high-order tensor product element is proposed to make the computations easy. The method of weighted r...

M. H. Berger

1982-01-01

11

Analysis of gas flow in a centrifuge  

Microsoft Academic Search

Onsager's sixth order, elliptic, partial differential equation with Ekman boundary layer suction describing linearized flow in a gas centrifuge has been rederived from the linearized compressible Navier-Stokes equations by asymptotic methods. A Galerkin weak formulation is detailed for two-dimensional flow with internal heat and momentum sources and sinks. An exact solution of Onsager's Pancake equation, with a point source or

1982-01-01

12

Analysis of gas flow in a centrifuge  

SciTech Connect

Onsager's sixth order, elliptic, partial differential equation with Ekman boundary layer suction describing linearized flow in a gas centrifuge has been rederived from the linearized compressible Navier-Stokes equations by asymptotic methods. A Galerkin weak formulation is detailed for two-dimensional flow with internal heat and momentum sources and sinks. An exact solution of Onsager's Pancake equation, with a point source or sink of axial momentum, in the long bowl limit has been developed. A high order, smooth, tensor product finite element that has nearest neighbor support is proposed to make practical computations for some symmetric and antisymmetric flow problems. A qualitative description of the singularities due to two-dimensional point sources or sinks is given along with approximations of the resultant flow fields. Effects of Ekman pumping and pure two-dimensional flow are illustrated. Finally, asymptotic solutions are given for the so-called auxiliary equation.

Berger, M.H.

1982-08-01

13

Theory and experiments on centrifuge cratering  

Microsoft Academic Search

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

R. M. Schmidt; K. A. Holsapple

1980-01-01

14

Centrifugal gas separator with electric motor drive  

Microsoft Academic Search

escribed which employs a vertically oriented centrifuge drum mounted on ; suitable bearings within a stationary housing and driven by an electric motor. ; The electric motor is constructed in annular form with its stator portion fixed ; to the stationary housing and its rotor portion fixed to the centrifuge drum and ; positioned generally below its stator portion. When

H. Tahara; M. Sakurai; H. Yamada

1973-01-01

15

Theory and experiments on centrifuge cratering  

NASA Astrophysics Data System (ADS)

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 continuum 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 constitutive 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 rate-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 g3E. Consequently, experiments at 500 G with 8 grams of explosives can be used to simulate a kiloton in the field. A series of centrifuge experiments was performed to validate the derived similarity requirements and to determine the practicality of applying the technique to dry granular soils having little or no cohesion. Ten shots using Ottawa sand at various gravities confirmed reproducibility of results in the centrifuge environment, provided information on particle size effects, and demonstrated the applicability of the derived similitude requirements. These experiments used 0.5-4 grams of pentaerythritol-tetranitrate (PETN) and 1.7 grams of lead-azide explosives. They were placed at zero depth of burial and were detonated at gravities up to 450 G. These results provide rules for scaling crater dimensions in Ottawa sand over a range of more than 10 orders of magnitude in total energy release.

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

1980-01-01

16

Power Supply to Gas Centrifuge Uranium Enrichment Plant  

Microsoft Academic Search

This paper presents an overview of planning for and construction of the power supply and distribution systems for a major new gas centrifuge uranium enrichment plant near Portsmouth, Ohio. Unusually reliable systems are dictated by requirements for continuity of production.

James Nelson; Ernest Johnson

1982-01-01

17

Theory of centrifugally driven magnetospheric diffusion  

SciTech Connect

A general model of centrifugally driven diffusion is formulated that incorporates the effects of the pressure gradient of a radiation belt ion population and includes a realistic precipitation loss rate of the radiation belt ions that takes on a spatially peaked form, leading to a spatially varying ionospheric conductivity. The model is applied specifically to Jupiter. Model solutions for the flux tube content of the radiation belt ion population are found to compare favorably with reported Voyager 1 observations of ions in the energy range 0.2-30 MeV. Solution profiles for the flux-tube content of the cool Iogenic ion population typically favor a gradient near L = 7.5 of between one-half and one-third of the value originally reported by Bagenal and Sullivan (1981) and Siscoe et al. (1981). The model solutions are characterized by unexpectedly low values of the precipitation parameter. 25 references.

Summers, D.; Thorne, R.M.; Mei, Y.

1988-05-01

18

The American Gas Centrifuge Past, Present, and Future  

SciTech Connect

The art of gas centrifugation was born in 1935 at the University of Virginia when Dr. Jesse Beams demonstrated experimentally the separation of chlorine isotopes using an ultra-high speed centrifuge. Dr. Beam’s experiment initiated work that created a rich history of scientific and engineering accomplishment in the United States in the art of isotope separation and even large scale biological separation by centrifugation. The early history of the gas centrifuge development was captured in a lecture and documented by Dr. Jesse Beams in 1975. Much of Dr. Beams lecture material is used in this paper up to the year 1960. Following work by Dr. Gernot Zippe at the University of Virginia between 1958 and 1960, the US government embarked on a centrifuge development program that ultimately led to the start of construction of the Gas Centrifuge Enrichment Plant in Piketon Ohio in the late 1970’s. The government program was abandoned in 1985 after investing in the construction of two of six planned process buildings, a complete supply chain for process and centrifuge parts, and the successful manufacture and brief operation of an initial complement of production machines that would have met 15 percent of the planned capacity of the constructed process buildings. A declining market for enriched uranium, a glut of uranium enrichment capacity worldwide, and the promise of a new laser based separation process factored in the decision to stop the government program. By the late 1990’s it had become evident that gas centrifugation held the best promise to produce enriched uranium at low cost. In1999, the United States Enrichment Corporation undertook an initiative to revive the best of the American centrifuge technology that had been abandoned fourteen years earlier. This is an exciting story and one that when complete will enable the United States to maintain its domestic supply and to be highly competitive in the world market for this important energy commodity. (auth)

Waters, Dean

2004-09-15

19

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.

2011-11-30

20

Optimizing the separation performance of a gas centrifuge  

NASA Astrophysics Data System (ADS)

Gas centrifuges were originally developed for the enrichment of U^235 from naturally occurring uranium for the purpose of providing fuel for nuclear power reactors and material for nuclear weapons. This required the separation of a binary mixture composed of U^235 and U^238. Since the end of the cold war, a surplus of enriched uranium exists on the world market, but many centrifuge plants exist in numerous countries. These circumstances together with the growing demand for stable isotopes for chemical and physical research and in medical science has led to the exploration of alternate applications of gas centrifuge technology. In order to acieve these multi-component separations, existing centrifuges must be modified or new centrifuges must be designed. In either case, it is important to have models of the internal flow fields to predict the separation performance and algorithms to seek the optimal operating conditions of the centrifuges. Here, we use the Onsager pancake model of the internal flow field, and we present an optimization strategy which exploits a similarity parameter in the pancake model. Numerical examples will be presented.

Wood, H. G.

1997-11-01

21

New Measures to Safeguard Gas Centrifuge Enrichment Plants  

Microsoft Academic Search

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

Whitaker Jr. James; James R Garner; Michael Whitaker; Dunbar Lockwood; Kimberly V Gilligan; James R Younkin; David A Hooper; James J Henkel; Alan M Krichinsky

2011-01-01

22

Parallel centrifugal gas compressors can be controlled more effectively  

SciTech Connect

Energy efficiency of parallel, centrifugal gas compressors can be improved by controlling the compressors to unload simultaneously to their surge limits. Simultaneous unloading to the surge limits can also allow more precise pressure control, provide better compressor protection, and allow simpler automated control systems. Specific power consumption is also offered as an improved definition of energy efficiency. Because polytropic efficiency, the most common efficiency measure, defines only the energy efficiency to compress a gas between the inlet port and the discharge port of a compressor, it does not account for the efficiency of gas delivery to the user. Specific power consumption includes energy costs that must be paid for but which are not accounted for by polytropic efficiency. This first of two articles discusses the concept of simultaneous loading and unloading of centrifugal compressors and compares the method with other control strategies. The concept of specific power consumption is also defined. The conclusion describes an algorithm for simultaneous loading and unloading to the surge limit. The efficiency and reliability of centrifugal compressors can be severely limited by the control system. Less-than-effective controls, rather than mechanical design, is often the cause of lost efficiency, shutdowns, and damage.

Staroselsky, N.; Ladin, L.

1986-11-03

23

Advanced technology for enrichment monitoring for gas centrifuge enrichment plants  

Microsoft Academic Search

We report our developments of the next generation of uranium enrichment monitoring technology for gas centrifuge enrichment\\u000a plants (GCEPs). The main challenge presented by current technology is the need for periodic replacement of the short half-life\\u000a (1.27 year) 109Cd transmission source. We report on a transmission source at the 22.1 keV K-edge of ruthenium based on an X-ray tube with\\u000a a “notch”

K. D. Ianakiev; J. M. Goda; T. R. Hill; C. E. Moss; J. J. Ong; M. T. Paffett; R. F. Parker; M. T. Swinhoe

2009-01-01

24

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

25

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

26

Remarks on the Axial Flow Taper in a Countercurrent Gas Centrifuge.  

National Technical Information Service (NTIS)

The effect of an axially varying countercurrent circulation rate in a gas centrifuge on the efficiency factors, e/sub I/ (the ideality efficiency) and e/sub C/ (the circulation efficiency), is investigated. The optimum value of the centrifuge parameter, m...

E. Von Halle

1983-01-01

27

Characteristics of the Gas Centrifuge for Uranium Enrichment and Their Relevance for Nuclear Weapon Proliferation  

Microsoft Academic Search

This article presents an analytical model, originally developed in the 1980s, for the gas centrifuge and uses this methodology to determine the main design and operational characteristics of several hypothetical centrifuge designs. A series of simulations for a typical first-generation machine is used to assess the relevance of important breakout scenarios, including batch recycling and cascade interconnection, using either natural

ALEXANDER GLASER

2008-01-01

28

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

29

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

30

Lateral fluid forces on whirling centrifugal impeller. I - Theory. II - Experiment in vaneless diffuser  

Microsoft Academic Search

Lateral fluid forces acting on a rotating centrifugal impeller in whirling motion are analyzed using unsteady potential flow theory. Impellers operating in diffusers with and without vanes are modeled and the fluid forces calculated for different whirl speeds and flow rates. The influences of these parameters are clarified by parametric calculations. The results for whirling impellers operating in vaneless diffusers

H. Shoji; H. Ohashi

1987-01-01

31

An accurate theory of Mercury's rotation and centrifugal librations  

Microsoft Academic Search

The internal structure of Mercury is the most puzzling among the terrestrial planets. MESSENGER and the upcoming Bepi-Colombo space missions as well as ground-based radar measurements will play an important role in furthering our understanding of the structure, formation, and evolution of Mercury. A complete theory of the coupled spin-orbit motion of Mercury within the Solar System is an essential

N. Rambaux; T. van Hoolst; V. Dehant; E. Bois

2005-01-01

32

Stability analysis and testing of a train of centrifugal compressors for high pressure gas injection  

Microsoft Academic Search

This paper describes the rotor dynamic stability analysis and the PTC-10 Class 1 test of a three body centrifugal compressor train for high pressure natural gas injection services. This train had a full load full pressure string test on hydrocarbon gases to a final discharge pressure of 500 BAR (7250 PSIA). Each compressor is of the back to back configuration,

E. A. Memmott

1999-01-01

33

On the enrichment of low-abundant isotopes of light chemical elements by gas centrifuges  

Microsoft Academic Search

A brief review of the main areas for the application of the isotopes 15N and 13C is made. Separation of the nitrogen isotopes in a single gas centrifuge in the form of pure nitrogen, ammonia, and trifluoride of nitrogen as well as the carbon isotopes in the form of carbon dioxide has been studied by means of numerical simulation. The

V. D Borisevich; O. E Morozov; Yu. P Zaozerskiy; G. M Shmelev; Yu. D Shipilov

2000-01-01

34

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

35

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

36

CENTRIFUGE END CAP  

DOEpatents

An end cap for ultra-gas centrifuges is designed to impart or remove angular momentum to or from the gas and to bring the entering gas to the temperature of the gas inside the centrifuge. The end cap is provided with slots or fins for adjusting the temperature and the angular momentum of the entering gas to the temperature and momentum of the gas in the centrifuge and is constructed to introduce both the inner and the peripheral stream into the centrifuge.

Beams, J.W.; Snoddy, L.B.

1960-08-01

37

Specialized centrifugal compressors for natural gas injection at 9200 psig  

Microsoft Academic Search

A schematic drawing of the Ekofisk Phillips Norway Group plant shows the various steps to gas reinjection. The first commercial crude oil is being produced from this newly discovered giant North Sea oil field. During the second half of 1973, a complete gas separation plant and a reinjection plant will be placed in operation making it possible to recover all

1973-01-01

38

Experience in full-load testing of natural gas centrifugal compressors for rotordynamics improvements  

Microsoft Academic Search

During full-load shop tests under natural gas, two multistage centrifugal compressors exhibited subsynchronous vibrations. Both of them are low-flow, high-pressure, high rotational speed compressors, and are fitted with tilting and bearings and dry gas seals. A rotating stall problem was first eliminated by a modification of the diffuser geometry. Then, aerodynamic excitations caused the rotors to operate at their stability

A. Gelin; J.-M. Pugnet; D. Bolusset; P. Friez

1997-01-01

39

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

40

Numerical Studies of the Isotope Distribution in a Gas Centrifuge Using a Tapered, Double-Parabolic Axial Flow.  

National Technical Information Service (NTIS)

Using a numerical technique developed previously (K/CSD/TM-36), a series of academic problems relating to the isotope distribution in a gas centrifuge has been solved. The centrifuge configuration used was the Rome machine specified in the proceedings of ...

J. E. Park

1983-01-01

41

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

42

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

43

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

SciTech Connect

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

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

1998-04-01

44

Lateral fluid forces on whirling centrifugal impeller. I - Theory. II - Experiment in vaneless diffuser  

NASA Astrophysics Data System (ADS)

Lateral fluid forces acting on a rotating centrifugal impeller in whirling motion are analyzed using unsteady potential flow theory. Impellers operating in diffusers with and without vanes are modeled and the fluid forces calculated for different whirl speeds and flow rates. The influences of these parameters are clarified by parametric calculations. The results for whirling impellers operating in vaneless diffusers show that the fluid forces exert a damping effect on the rotor whirling motion at all operating conditions. The results for impellers operating in vaned diffusers or guide vanes show that the time averaged values of fluid forces remain almost unchanged, while there are significant instantaneous fluctuations due to the impeller/guide vane interactions.

Shoji, H.; Ohashi, H.

1987-06-01

45

Experience in full-load testing of natural gas centrifugal compressors for rotordynamics improvements  

SciTech Connect

During full-load shop tests under natural gas, two multistage centrifugal compressors exhibited subsynchronous vibrations. Both of them are low-flow, high-pressure, high rotational speed compressors, and are fitted with tilting and bearings and dry gas seals. A rotating stall problem was first eliminated by a modification of the diffuser geometry. Then, aerodynamic excitations caused the rotors to operate at their stability limit, and high vibration levels were observed at the first natural frequency. A complete rotordynamics analysis was performed in order to model precisely all the fluid-structure interactions. Modifications of the rotor designs were implemented, consisting in optimizing conveniently the bearing pads, replacing the toothed labyrinth seals of the balance pistons by damping honeycomb seals, fitting them with improved shunt hole systems. In addition, the dry gas seals were found to have been damaged, due to thermal effects, and further modifications were implemented to eliminate this problem. Final full load tests demonstrated a satisfactory behavior of both centrifugal compressors.

Gelin, A.; Pugnet, J.M.; Bolusset, D.; Friez, P. [Framatome, Le Creusot (France)

1997-10-01

46

NDA measurement of the enrichment of uranium in the pipe for a gas centrifuge enrichment plant  

SciTech Connect

A NDA instrument has been developed to determine the enrichment of gas phase uranium in pipes for a gas centrifuge enrichment plant. The enrichment of gas phase uranium could be measured by combining the passive gamma rays measurement with X-ray fluorescent analysis. The passive gamma rays measurement has extensively been performed in previous works. Successively the amount of deposited uranium has been measured for a long-term plant operation. Some increase of deposited uranium was observed. Determination of total mass of uranium in a pipe was studied by X-ray fluorescent analysis on a test loop system. It was found that total mass of gaseous UF/sub 6/ in the pipe could be determined accurately enough in implementation of safeguards.

Hori, M.; Ishiga, T.; Akiba, M.; Tani, A.; Omae, M.

1986-01-01

47

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

48

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

49

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

50

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

51

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

52

Calculation of UF sub 6 gas density, temperature, pressure, and Mach number changes across a normal shock in a gas-centrifuge environment  

NASA Astrophysics Data System (ADS)

The nonlinear Rankine-Hugoniot equations are solved to obtain changes in UF6 gas density, temperature, pressure, and Mach number across a normal shock in a gas centrifuge environment. Effects of the nonlinear temperature variation of the enthalpy and specific heats of UF6 are included to insure that realistic predictions of gas temperature and pressure are obtained. Tables of values of gas density, temperature, pressure, and Mach number describing conditions behind a normal shock are presented as functions of the upstream Mach number and the upstream gas temperature. Values of the gas stagnation temperature and stagnation pressure are also included. The tables give tabular results corresponding to centrifuge wall speeds ranging from 350 m/s to 1100 m/s.

Gentry, R. A.

1983-03-01

53

A Finite-Difference Numerical Method for Onsager's Pancake Approximation for Fluid Flow in a Gas Centrifuge  

SciTech Connect

Gas centrifuges exhibit very complex flows. Within the centrifuge there is a rarefied region, a transition region, and a region with an extreme density gradient. The flow moves at hypersonic speeds and shock waves are present. However, the flow is subsonic in the axisymmetric plane. The analysis may be simplified by treating the flow as a perturbation of wheel flow. Wheel flow implies that the fluid is moving as a solid body. With the very large pressure gradient, the majority of the fluid is located very close to the rotor wall and moves at an azimuthal velocity proportional to its distance from the rotor wall; there is no slipping in the azimuthal plane. The fluid can be modeled as incompressible and subsonic in the axisymmetric plane. By treating the centrifuge as long, end effects can be appropriately modeled without performing a detailed boundary layer analysis. Onsager's pancake approximation is used to construct a simulation to model fluid flow in a gas centrifuge. The governing 6th order partial differential equation is broken down into an equivalent coupled system of three equations and then solved numerically. In addition to a discussion on the baseline solution, known problems and future work possibilities are presented.

de Stadler, M; Chand, K

2007-11-12

54

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

55

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

56

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

57

CENTRIFUGE APPARATUS  

DOEpatents

A high-speed centrifuge for the separation of gaseous isotopes is designed comprising a centrifugal pump mounted on the outlet of a centrifuge bowl and arranged to pump the heavy and light fractions out of the centrifuge bowl in two separate streams.

Skarstrom, C.; Urey, H.C.; Cohen, K.

1960-08-01

58

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

59

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

60

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

61

Corrosion evaluation of cooling-water treatments for gas centrifuge facilities  

SciTech Connect

The corrosion resistance of six different types of weighted metal coupons was evaluated at 29/sup 0/C (84/sup 0/F) in flowing water containing nitrite-borate-silicate corrosion inhibitors. The question for evaluation was whether it would be more advantageous: (1) to drain the treated cooling water from the centrifuge machine and to expose them to moisture-laden air over an assumed shop downtime and repair perid of 1 month; or (2) to let the treated cooling water remain stagnant in the machines during this downtime. The moisture-laden-air exposure was more detrimental.

Schmidt, C. R.; Meredith, P. F.

1980-11-24

62

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

63

Centrifugal compressors  

Microsoft Academic Search

Design of centrifugal compressors and performance prediction methods are presented. Impeller work equation, impeller velocity triangles, impeller sweepback, overall pressure rise characteristics, surges, and design analysis are treated.

R. L. Elder; C. P. Forster

1987-01-01

64

Centrifugal compressors  

NASA Astrophysics Data System (ADS)

Design of centrifugal compressors and performance prediction methods are presented. Impeller work equation, impeller velocity triangles, impeller sweepback, overall pressure rise characteristics, surges, and design analysis are treated.

Elder, R. L.; Forster, C. P.

65

CENTRIFUGAL SEPARATORS  

DOEpatents

A centrifugal separator is described for separating gaseous mixtures where the temperature gradients both longitudinally and radially of the centrifuge may be controlled effectively to produce a maximum separation of the process gases flowing through. Tbe invention provides for the balancing of increases and decreases in temperature in various zones of the centrifuge chamber as the result of compression and expansions respectively, of process gases and may be employed effectively both to neutralize harmful temperature gradients and to utilize beneficial temperaturc gradients within the centrifuge.

Skarstrom, C.

1959-03-10

66

Results from uranium deposition studies for development of a limited frequency-unannounced access (LFUA) inspection strategy for gas centrifuge enrichment plants  

SciTech Connect

Uranium deposition studies were performed on a test loop system designed to simulate process gas flow through the header piping of a gas centrifuge enrichment plant. The objectives of these studies were to investigate the effectiveness of an in-line gaseous cleaning agent in removing uranium in pipe deposits and to analyze long-term deposition growth and isotopic exchange under simulated centrifuge plant operating conditions. The test loop studies are described, the results are reported, and the implications for analyzing actual plant data are discussed. Results indicate that (1) 93% of the uranium deposit is removed within 15 min when a pipe is pressurized with gaseous ClF/sub 3/, (2) the isotopic abundance of a highly enriched uranium deposit remains unchanged when UF/sub 6/ of a lower assay is introduced into the pipe, and (3) air inleakage will be the cause of the largest deposits in centrifuge plant process header pipes. 1 ref., 3 figs., 3 tab.

Cooley, J.N.; Fields, L.W.; Swindle, D.W.

1985-05-16

67

Results from uranium deposition studies for development of a Limited Frequency-Unannounced Access (LFUA) inspection strategy for gas centrifuge enrichment plants  

SciTech Connect

Uranium deposition studies were performed on a test loop system designed to simulate process gas flow through the header piping of a gas centrifuge enrichment plant. The objectives of these studies were to investigate the effectiveness of an in-line gaseous cleaning agent in removing uranium in pipe deposits and to analyze long-term deposition growth and isotopic exchange under simulated centrifuge plant operating conditions. The test loop studies are described, the results are reported, and the implications for analyzing actual plant data are discussed. Results indicate that: 93% of the uranium deposit is removed within 15 min when a pipe is pressurized with gaseous ClF/sub 3/; the isotopic abundance of a highly enriched uranium deposit remains unchanged when UF/sub 6/ of a lower assay is introduced into the pipe; and air inleakage will be the cause of the largest deposits in centrifuge plant process header pipes. 3 refs., 3 figs., 3 tabs.

Cooley, J.N.; Fields, L.W.; Swindle, D.W.

1985-06-01

68

Results from uranium deposition studies for development of a limited frequency-unannounced access inspection strategy for gas centrifuge enrichment plants  

SciTech Connect

Uranium deposition studies were performed on a test loop system designed to simulate process gas flow through the header piping of a gas centrifuge enrichment plant. The objectives of these studies were to investigate the effectiveness of an in-line gaseous cleaning agent in removing uranium in pipe deposits and to analyze long-term deposition growth and isotopic exchange under simulated centrifuge plant operating conditions. The test loop studies are described, the results are reported, and the implications for analyzing actual plant data are discussed. Results indicate that (1) 93% of the uranium deposit is removed within 15 min when a pipe is pressurized with gaseous ClF/sub 3/, (2) the isotopic abundance of a highly enriched uranium deposit remains unchanged when UF/sub 6/ of a lower assay is introduced into the pipe, and (3) air inleakage will be the cause of the largest deposits in centrifuge plant process header pipes.

Cooley, J.N.; Fields, L.W.; Swindle, D.W.

1985-01-01

69

Microstructural characterization of rapidly solidified Type 304 stainless steel. [Powders produced by vacuum gas and centrifugal atomization  

SciTech Connect

The microstructures of rapidly solidified Type 304 stainless steel powders produced by vacuum gas (VGA) and centrifugal (CA) atomization have been examined. The solidification morphology and phase distribution have been characterized using optical and scanning electron microscopy, and the relative amounts of ferrite and austenite have been quantified using x-ray diffraction. It has been found that most CA powder particles contain both fcc and bcc phases, with the bcc phase predominating at small particle sizes and the fcc phase at large particle sizes. The VGA powder generally contains less ferrite, with very little dependence on the particle size. In both powders the ferrite was found to be metastable and to transform to austenite on annealing at 900/sup 0/C.

Wright, R.N.; Flinn, J.E.; Korth, G.E.

1985-11-01

70

Centrifugal Compressor Aeroelastic Analysis Code  

Microsoft Academic Search

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

Theo G. Keith Jr.; Rakesh Srivastava

2002-01-01

71

Theory of a multistage light gas gun  

Microsoft Academic Search

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

J. G. Linhart; F. Cattani

2007-01-01

72

Approach to IAEA material-balance verification with intermittent inspection at the Portsmouth Gas Centrifuge Enrichment Plant  

SciTech Connect

This paper describes a potential approach by which the International Atomic Energy Agency (IAEA) might verify the nuclear-material balance at the Portsmouth Gas Centrifuge Enrichment Plant (GCEP) for the circumstance in which the IAEA inspections occur on an intermittent basis. The verification approach is a variation of the standard IAEA attributes/variables measurement-verification method. This alternative approach is useful and applicable at the Portsmouth GCEP, which will ship all its product and tails UF/sub 6/ to United States facilities not eligible for IAEA safeguards. The paper reviews some of the relevant results of the Hexapartite Safeguards Project (HSP), describes the standard IAEA material-balance-verification approach for bulk-handling facilities, and provides the procedures to be followed in handling and processing UF/sub 6/ cylinders at the Portsmouth GCEP. The paper then discusses the assumptions made in the approach, and derives a formula for the probability with which the IAEA could detect the diversion of a significant quantity of uranium (75 kg of U-235 in depleted, normal, and low-enriched uranium) if this method were applied. The paper also provides numerical examples of IAEA detection probability should the operator divert uranium from the feed, product, or tails streams for the Portsmouth GCEP with a capacity of 1100 tonnes of separative work per year.

Gordon, D.M.; Sanborn, J.B.

1984-05-18

73

Recent ORNL experience in site performance prediction: the Gas Centrifuge Enrichment Plant and the Oak Ridge Central Waste Disposal Facility  

SciTech Connect

The suitability of the Portsmouth Gas Centrifuge Enrichment Plant Landfill and the Oak Ridge, Tennessee, Central Waste Disposal Facility for disposal of low-level radioactive waste was evaluated using pathways analyses. For these evaluations, a conservative approach was selected; that is, conservatism was built into the analyses when assumptions concerning future events had to be made or when uncertainties concerning site or waste characteristics existed. Data from comprehensive laboratory and field investigations were used in developing the conceptual and numerical models that served as the basis for the numerical simulations of the long-term transport of contamination to man. However, the analyses relied on conservative scenarios to describe the generation and migration of contamination and the potential human exposure to the waste. Maximum potential doses to man were calculated and compared to the appropriate standards. Even under this conservative framework, the sites were found to provide adequate buffer to persons outside the DOE reservations and conclusions concerning site capacity and site acceptability were drawn. Our experience through these studies has shown that in reaching conclusions in such studies, some consideration must be given to the uncertainties and conservatisms involved in the analyses. Analytical methods to quantitatively assess the probability of future events to occur and to quantitatively determine the sensitivity of the results to data uncertainty may prove useful in relaxing some of the conservatism built into the analyses. The applicability of such methods to pathways analyses is briefly discussed.

Pin, F.G.

1985-01-01

74

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

75

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

76

Theories and Conflict: The Origins of Natural Gas. Instructional Materials.  

ERIC Educational Resources Information Center

This unit explores a recent and controversial theory of the origin of much of the Earth's natural gas and oil. The materials provided will give students the opportunity to: (1) gain an understanding of science and what is involved in the acceptance or rejection of theories; (2) learn about fossil fuels, especially natural gas; (3) learn the…

Anderson, Susan

77

Centrifugal Compressor Aeroelastic Analysis Code  

NASA Astrophysics Data System (ADS)

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

78

The construction, testing, and installation of a 6500 r/min 15 000-hp adjustable-speed electric drive for a centrifugal gas compressor  

SciTech Connect

The construction, testing, and installation of a 6500 r/min 15 000-hp adjustable-speed electric drive for a centrifugal gas compressor is presented. A power electronic converter is applied to control the speed of a 5-kV motor. The motor is directly coupled to a 6500 r/min compressor and replaced a steam turbine. Dual converters are used in a twelve-pulse arrangement at both the utility and the motor. The motor is of solid rotor construction, with dual 30/sup 0/ displaced stator windings. Finite-element analysis is used to optimize the motor designs for use with a variable-frequency static converter. Full-power tests are completed which confirm theoretical predictions on losses, performance, and operation. The electrical drive takes up considerably less space and is much more efficient than the steam turbine it replaced.

Lawrence, R.G.; Finney, D.; Davidson, D.F.

1988-07-01

79

Theory of an Optically Pumped Gas Laser.  

National Technical Information Service (NTIS)

A theoretical description of the steady-state operation of an optically-pumped gas laser is presented. The three-level gas is described by a suitably modified form of the Boltzmann equation. This formulation is intermediate between the rate equation and s...

J. J. Healy T. F. Morse

1972-01-01

80

Unified Positive Column Theory of Gas Discharges.  

National Technical Information Service (NTIS)

The effects of electron impact ionization, three-body recombination, and a thermal energy balance are considered on the positive column of a gas discharge confined between plane parallel walls. The diffusion flux equations (with temperature dependent ioni...

I. M. Cohen A. M. Whitman

1972-01-01

81

Benchtop, Refrigerator Centrifuges  

Cancer.gov

CHECKLIST FOR BENCHTOP, REFRIGERATED CENTRIFUGES CG 15 Any program area utilizing the SAIC-Frederick procurement system for benchtop, refrigerated centrifuges must adhere to this process Instructions: 1) Check off model from list below and attach a list

82

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.

83

Geotechnical centrifuge under construction  

Microsoft Academic Search

Modifications are underway at the National Aeronautics and Space Administration (NASA) Ames Research Center in California to transform a centrifuge used in the Apollo space program to the largest geotechnical centrifuge in the free world. The centrifuge, to be finished in August and opened next January, following check out and tuning, will enable geoscientists to model stratigraphic features down to

Barbara T. Richman

1982-01-01

84

Analysis of gas motion in the clearance between the cover disk and the casing of centrifugal compressor stage  

Microsoft Academic Search

The possibility of application of FLUENT and CFX programs for improving the flow section for gas motion in the clearance between\\u000a the cover disk and the casing in the labyrinth seal has been explored. The friction loss in the clearance and the rate of\\u000a mass flow through the labyrinth seal have been assessed. The gas flow pattern and the key

Yu. B. Galerkin; K. V. Soldatova

2007-01-01

85

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

86

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

87

Dust-Gas Interrelations In Comets: Observations And Theory  

Microsoft Academic Search

The development of the expanding atmosphere from the evaporating cometary nucleus has traditionally focused on observing and modeling the separate development of two distinct components, gas and dust,which are coupled dynamically with one another at distances out to a few tens of cometary radii. In the last decade or so, however, direct evidence from observations and suggestions from theory suggest

Michael R. Combi; Konstantin Kabin; Darren L. Dezeeuw; Tamas I. Gombosi; Kenneth G. Powell

1997-01-01

88

Kinetic theory of steady chemical nucleation in the gas phase  

Microsoft Academic Search

We develop a kinetic theory of nucleation involving chemical reactions in the gas phase. For the basis of deriving the chemical nucleation rate, chemical kinetic considerations are presented on the steady current density and the effective rate constants of the overall reaction, which is a sum of a sequential elementary reactions. We formulate the steady rate of chemical nucleation in

T. Yamamoto; T. Chigai; S. Watanabe; T. Kozasa

2001-01-01

89

Development of turbine driven centrifugal compressors for non-condensible gas removal at geothermal power plants. Final report  

SciTech Connect

Initial field tests have been completed for a Non-Condensible Gas (NCG) turbocompressor for geothermal power plants. It provides alternate technology to steam-jet ejectors and liquid-ring vacuum pumps that are currently used for NCG removal. It incorporates a number of innovative design features to enhance reliability, reduce steam consumption and reduce O&M costs. During initial field tests, the turbocompressor has been on-line for more than 4500 hours as a third stage compressor at The Geysers Unit 11 Power Plant. Test data indicates its overall efficiency is about 25% higher than a liquid-ring vacuum pump, and 250% higher than a steam-jet ejector when operating with compressor inlet pressures of 12.2 in-Hga and flow rates over 20,000 lbm/hr.

NONE

1997-12-16

90

Dust-Gas Interrelations In Comets: Observations And Theory  

Microsoft Academic Search

The development of the expanding atmosphere from the evaporating cometary nucleus has traditionally focused on observing and\\u000a modeling the separate development of two distinct components, gas and dust,which are coupled dynamically with one another\\u000a at distances out to a few tens of cometary radii. In the last decade or so, however, direct evidence from observations and\\u000a suggestions from theory suggest

Michael R. Combi; KONSTANTIN KABIN; Darren L. DeZEEUW; Tamas I. Gombosi; Kenneth G. Powell

1997-01-01

91

METHOD OF CENTRIFUGE OPERATION  

DOEpatents

A method of isotope separation is described in which two streams are flowed axially of, and countercurrently through, a cylindrical centrifuge bowl. Under the influence of a centrifugal field, the light fraction is concentrated in a stream flowing through the central portion of the bowl, whereas the heavy fraction is concentrated in a stream at the periphery thereof.

Cohen, K.

1960-05-10

92

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

93

Open-cycle centrifugal vapor-compression heat pump  

Microsoft Academic Search

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

L. R. Burgmeier; J. E. Horner

1987-01-01

94

Subjective stress factors in centrifuge training for military aircrews.  

PubMed

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 into three constructs by factor analysis, theory lecture, centrifuge equipment, and physical fitness. Considerable interpenetration was discernible between these factors and military rank, age, length of service, flight hours accrued, and type of aircraft piloted. Identifying and quantifying the perceived stressors experienced in human-use centrifuge training enables aviators, astronauts, and air forces of the world to determine which constructs perceptibly increase or alleviate the perceived stress undergone by trainees when partaking in centrifuge training. PMID:22036449

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

2011-10-27

95

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

96

Theory of the nonsteady diffusion growth of a gas bubble in a supersaturated solution of gas in liquid  

Microsoft Academic Search

Using a self-similar approach a general nonsteady theory is elaborated for the case of the diffusion growth of a gas bubble in a supersaturated solution of gas in liquid. Due to the fact that the solution and the bubble in it are physically isolated, the self-similar approach accounts for the balance of the number of gas molecules in the solution

A. P. Grinin; F. M. Kuni; G. Yu. Gor

2008-01-01

97

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

98

SEAL FOR HIGH SPEED CENTRIFUGE  

DOEpatents

A seal is described for a high speed centrifuge wherein the centrifugal force of rotation acts on the gasket to form a tight seal. The cylindrical rotating bowl of the centrifuge contains a closure member resting on a shoulder in the bowl wall having a lower surface containing bands of gasket material, parallel and adjacent to the cylinder wall. As the centrifuge speed increases, centrifugal force acts on the bands of gasket material forcing them in to a sealing contact against the cylinder wall. This arrangememt forms a simple and effective seal for high speed centrifuges, replacing more costly methods such as welding a closure in place.

Skarstrom, C.W.

1957-12-17

99

Subsurface electrical centrifugal pumps  

SciTech Connect

The first subsurface electrical centrifugal pump for oilwell service in the U.S. was installed in the Russell field, KS, in 1926. Since that time many improvements have increased the efficiency of the pump at various pumping rates and depths in a variety of casing sizes. Each oil well has a different producing environment that the design engineer must consider to optimize the pumping installation for maximum service life. This paper discusses the major items involved in selection of a subsurface electrical centrifugal pump for a specific application. Additionally, installation, operating, and servicing practices are discussed.

Coltharp, E.D.

1984-04-01

100

Progress of coal-formed gas geological theory and its status in natural gas industry in China  

Microsoft Academic Search

The concept of coal measures forming natural gas was proposed by German scholars in the 1940s. By the late 1970s, coal-formed gas accounted for almost 70% of the proved gas reserves in the world. Geological theory of coal-formed gas in China has gone through a process of introduction, absorption, innovation, development and forming into a system. The theoretical system, which

Zhao Wenzhi; Wang Hongjun; Qian Kai

2009-01-01

101

The effect of interfacial resistance on gas absorption with chemical reaction: The film theory model  

Microsoft Academic Search

A simple film theory model yielding a closed?form solution is presented for the analysis of isothermal gas absorption with a chemical reaction taking into account the effect of interfacial resistance. The analysis could be particularly important for a rational design of wet scrubbing systems for gaseous pollutant removal with impurities contaminating the gas?liquid interface. The film theory avoids time dependence

1987-01-01

102

A Centrifugal Compressor Seal  

Microsoft Academic Search

A new impeller-to-sump seal was developed for a line of hermetically sealed centrifugal compressor units. Tests, using an actual compressor unit, were made to simulate steady operating conditions. Both new seal configurations and the original seal were tested. A new seal configuration resulted in a 25:1 reduction in refrigerant leakage. The seal met all other technical and economic requirements dictated

M. L. Adams; A. A. Raimondi

1977-01-01

103

A miniature centrifugal pump  

Microsoft Academic Search

A miniature centrifugal pump designed to circulate helium in a flow loop is described. It is designed to operate in the liquid helium temperature range under ambient pressures up to 100 atm (107 N?m2), producing a maximum flow rate of 50 cm3?sec and a maximum pressure rise of 3400 N?m2. The operating characteristics obtained from preliminary tests with cold nitrogen

H. Sixsmith; Patricia Giarratano

1970-01-01

104

Kinetic theory of steady chemical nucleation in the gas phase  

NASA Astrophysics Data System (ADS)

We develop a kinetic theory of nucleation involving chemical reactions in the gas phase. For the basis of deriving the chemical nucleation rate, chemical kinetic considerations are presented on the steady current density and the effective rate constants of the overall reaction, which is a sum of a sequential elementary reactions. We formulate the steady rate of chemical nucleation in a multi-component vapor, in which nucleation occurs via the chemical reactions yielding a condensate having a stoichiometric composition. An exact expression of the steady nucleation rate is given together with its approximate formulas for practical applications. The present formulation is not concerned with any particular cluster model. The supersaturation ratio for a many-component vapor is defined so as to be a natural extension of that for a one-component vapor. It is shown that the transition probabilities due to growth and decay of the clusters are of the same form as the growth and evaporation rates in a one-component vapor.

Yamamoto, T.; Chigai, T.; Watanabe, S.; Kozasa, T.

2001-12-01

105

Statistical Mechanics of a Coulomb Gas With Finite Size Particles: A Lattice Field Theory Approach.  

National Technical Information Service (NTIS)

A recently proposed lattice field theory approach to the statistical mechanics of a classical Coulomb gas is generalized to treat gas particles of finite size. To do this, a repulsive Yukawa interaction between all pairs of gas particles is added to the u...

R. D. Coalson A. M. Walsh A. Duncan N. Ben-Tal

1995-01-01

106

Tensorial slip theory for gas flows and comparison with molecular dynamics simulations using an anisotropic gas-wall collision mechanism  

NASA Astrophysics Data System (ADS)

In this paper we examine the anisotropic slip theory for gas flows based on tangential accommodation coefficients and compare it with molecular dynamics (MD) results. A special gas-wall boundary condition is employed within MD simulations to mimic the anisotropic gas-wall collision mechanism. Results from MD simulations with different surface orientations show good agreement with the slip quantification proposed in this work.

Pham, Thanh Tung; To, Quy Dong; Lauriat, Guy; Léonard, Céline

2013-05-01

107

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

108

CENTRIFUGAL MEMBRANE FILTRATION  

SciTech Connect

The overall project consists of several integrated research phases related to the applicability, continued development, demonstration, and commercialization of the SpinTek centrifugal membrane filtration process. Work performed during this reporting period consisted of Phase 2 evaluation of the SpinTek centrifugal membrane filtration technology and Phase 3, Technology Partnering. During Phase 1 testing conducted at the EERC using the SpinTek ST-IIL unit operating on a surrogate tank waste, a solids cake developed on the membrane surface. The solids cake was observed where linear membrane velocities were less than 17.5 ft/s and reduced the unobstructed membrane surface area up to 25%, reducing overall filtration performance. The primary goal of the Phase 2 research effort was to enhance filtration performance through the development and testing of alternative turbulence promoter designs. The turbulence promoters were designed to generate a shear force across the entire membrane surface sufficient to maintain a self-cleaning membrane capability and improve filtration efficiency and long-term performance. Specific Phase 2 research activities included the following: System modifications to accommodate an 11-in.-diameter, two-disk rotating membrane assembly; Development and fabrication of alternative turbulence promoter designs; Testing and evaluation of the existing and alternative turbulence promoters under selected operating conditions using a statistically designed test matrix; and Data reduction and analysis; The objective of Phase 3 research was to demonstrate the effectiveness of SpinTek's centrifugal membrane filtration as a pretreatment to remove suspended solids from a liquid waste upstream of 3M's WWL cartridge technology for the selective removal of technetium (Tc).

Daniel J. Stepan; Bradley G. Stevens; Melanie D. Hetland

1999-10-01

109

Centrifugal blower wheel  

SciTech Connect

A centrifugal blower wheel is described comprising a supporting disk, individually separate blower blades arranged in circumferentially spaced relation around the periphery of the disk, and a supporting construction for the ends of the blades at one end of the wheel comprising: (a) an endless wire hoop of an outer diameter less than the outer diameter defined by the blade portions of the wheel, (b) each blade having at the end thereof a flange which extends axially therefrom into radially overlaying relation with the hoop, and (c) all of the flanges being wrapped around the hoop to secure the blades to the hoop.

Reifschneider, A.P.

1988-04-19

110

The magnetic centrifugal mass filter  

NASA Astrophysics Data System (ADS)

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.

Fetterman, Abraham J.; Fisch, Nathaniel J.

2011-09-01

111

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

112

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

113

Advanced centrifugal contactor development  

SciTech Connect

As part of the Consolidated Fuel Reprocessing Program (CFRP) of the Oak Ridge National Laboratory (ORNL), compact centrifugal contactors were designed and prototypes were built for the Breeder Reprocessing Engineering Test (BRET) facility. These contactors were designed for a nominal throughput of 0.1 metric tons of heavy metal per day. While construction of BRET has been put on indefinite hold, development of the 5.5-cm-diam rotor centrifugal contactors has advanced due to their broad applicability in other areas of reprocessing. Development has been concentrated in three areas: (1) mass transfers, (2) hydraulics, and (3) fabrication. Mass transfer development has involved determining how the stage efficiency is affected by the rotor speed, phase ratio, and feed flow rate. Hydraulic efforts have focused on the cascade operation with individual stage failures. Fabrication development has resulted in reducing the number of rotor components from seven to four. This paper discusses the results of these development efforts. 20 refs., 10 figs., 6 tabs.

DeMuth, S.F.; Jubin, R.T.; Ladd, L.D.

1988-01-01

114

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

115

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

116

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

117

Modelling of multistage centrifugal compressor  

Microsoft Academic Search

Surge is an unstable operating mode of the centrifugal compressor that occurs at mass flows below the surge line, and it results in considerable loss of performance and efficiency of the compression system. Modelling of the centrifugal compressor is the basis of getting the surge line and carrying out anti-surge control. Based on fluid mechanics, mass and energy conservation principles,

Dapeng Niu; Aiping Shi; Yuqing Chang; Fuli Wang

2011-01-01

118

A Long Introduction to Economic Theory and Natural Gas  

Microsoft Academic Search

This paper has its origin in a long lecture that I gave at the ENI Corporate University in Milan, Italy, which I later extended for the natural gas portion of the course in oil and gas economics that I taught in 2007 at the Asian Institute of Technology, Bangkok (Thailand). What I attempt now is to utilize the discussions of

Ferdinand E. Banks

119

Theory and experiments on sweeping gas membrane distillation  

Microsoft Academic Search

A theoretical model is presented that describes sweeping gas membrane distillation processes through porous hydrophobic membranes. The approach considers the case in which the liquid feed and the sweeping gas counterflow in a plate and frame membrane module. The model developed emphasises the importance of the heat fluxes in the directions parallel and perpendicular to the membrane surface and permits

Mohamed Khayet; Paz Godino; Juan I. Mengual

2000-01-01

120

Immunoaffinity centrifugal precipitation chromatography.  

PubMed

Purification of proteins based on immunoaffinity has been performed using a solid support coated with antibody against the target proteins. The method requires immobilizing the antibody onto the solid support using protein A or G, and has a risk of adsorptive loss of target proteins onto the solid support. Centrifugal precipitation chromatography has been successfully used to purify enzymes, such as ketosteroid isomerase and hyaluronidase without the use of solid support. The purpose of this study is to demonstrate that immunoaffinity centrifugal precipitation chromatography is capable of isolating an antigen by exploiting antigen-antibody binding. The separation was initiated by filling both channels with 40% saturated ammonium sulfate (AS) of pH 4-4.5 followed by loading 20 microl of human plasma (National Institutes of Health blood bank) mixed with 2 mg of rabbit anti-HSA (human serum protein) antibody (Sigma). Then, the sample channel was eluted with water at 0.03 ml/min and AS channel with 40% AS solution of pH 4-4.5 at 1 ml/min until all non-binding components were eluted. Then, the releasing reagent (50% AS solution containing 0.5 M glycine and 10% ammonium hydroxide at pH 10) was introduced through the AS channel to release the target protein (HSA). The retained antibody was recovered by eluting the sample channel with water at 1 ml/min. A hollow fiber membrane device at the outlet (MicroKros, Spectrum, New Brunswick, NJ, USA) was provided on-line dialysis of the eluent before fractions were collected, so that the fractions could be analyzed by SDS-PAGE (sodium dodecyl sulfate - polyacrylamide gel electrophoresis) without further dialysis. The current method does not require immobilizing the antibody onto a matrix, which is used by the conventional immunoaffinity chromatography. This method ensures full recovery of the antigen and antibody, and it may be applied to purification of other proteins. PMID:17416378

Qi, Lin; Ito, Yoichiro

2007-03-30

121

Non-Equilibrium Theory of Gas-Liquid Chromatography  

Microsoft Academic Search

IN a gas-liquid chromatographic column the assumption of equilibrium demands that the rate constants for solute transfer between the gas and the liquid phases must be infinitely large and the flow-rates extremely small. In practical columns neither of these conditions is ever fulfilled; the kinetic rate constants are finite, and the use of extremely slow flow-rates is out of the

M. A. Khan

1960-01-01

122

On an isotropic and centrifugal force invariant layout of a conically shaped gas-lubricated high-speed spiral-groove bearing  

Microsoft Academic Search

The following elaboration discusses the analytically complete layout of a self-acting gas-lubricated high-speed conically shaped spiral-groove bearing as well as suggestions for practical realization. The simple conically shaped bearing is separated into two conical main bearings, which are situated at the ends of the cone-stump. Both have an identical angle size, but otherwise differ with regard to their bearing geometries

R. Dupont

2003-01-01

123

Theory of collisional electron spectroscopy for gas analysis  

SciTech Connect

We develop an analytical model for a proposed method of gas analysis. The method is based on collisional electron spectroscopy, where a limited number of electron scatterings on gas molecules inside the analyzer is permitted. The proposed method can be used to identify impurity species in a main gas from the resulted energy spectra of photoelectrons collected by the cathode. The photoelectrons are produced by vacuum ultraviolet-ionization of impurity species. Physical processes are explored in the case of detecting impurities in atmospheric air. The electron velocity distribution function inside the detector is derived. It is shown that the voltage dependence of the second derivative of the cathode current with respect to the applied cathode voltage can provide electron energy spectrum and subsequent identification of the impurity species.

Panasyuk, George Y. [Propulsion Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); Tsyganov, Alexander B. [Department of General and Technical Physics, St.-Petersburg State Mining University, St.-Petersburg (Russian Federation)

2012-06-01

124

Air gas dynamic spraying of powder mixtures: Theory and application  

NASA Astrophysics Data System (ADS)

The radial injection gas dynamic spray (RIGDS) technology of powder coatings deposition was considered for this work. A coating was created by injecting powders with variable compositions into a supersonic air jet and depositing powder on the substrate. This study describes the preliminary analysis of an air gas dynamic spray method realized by a portable RIGDS apparatus with a radial injection of powder. Attention was given to shock compaction processes during the coating structure formation and examples of powder mixtures utilization in RIGDS. It was shown that the operational parameters of supersonic powder-gas jet have a significant influence on the coating's microstructure, thus defining the high performance of the coating. Compaction and bonding of particles were analyzed.

Maev, R. Gr.; Leshchynsky, V.

2006-06-01

125

Kinetic Theory Analysis of Temperature Jump in a Polyatomic Gas  

Microsoft Academic Search

A kinetic theory analysis of the temperature jump at the wall and the temperature distribution near the wall in polyatomic gases has been made. The collision term in the Boltzmann equation is represented by a classical (BGK-type) polyatomic model. The problem is linearized by considering small temperature and density variations over their respective mean values, which leads to three simultaneous

J. T. Lin; D. R. Willis

1972-01-01

126

Kinetic Theory of Reactive Gas Mixtures with Application to Combustion  

Microsoft Academic Search

We consider a generalized Boltzmann equation valid for dilute, isotropic, polyatomic gas mixtures with chemical reactions. Depending on the ratio of characteristic times between reactive and inert collisions, various chemical regimes are obtained in the first order Enskog expansion and their compatibility with the Boltzmann H-theorem is investigated. We then review the mathematical structure of the transport linear systems resulting

A. Ern; V. Giovangigli

2003-01-01

127

Greenhouse Ventilation Rate: Theory and Measurement with Tracer Gas Techniques  

Microsoft Academic Search

Leakage and ventilation rates were measured in a four span glasshouse at Silsoe Research Institute. Two tracer gas techniques were used, a decay rate method with different positions of the leeward ventilator (0, 10 and 20% of the maximum opening) and a continuous injection method with the leeward ventilators open 10%. The influences of wind speed, wind direction and temperature

F. J. Baptista; B. J. Bailey; J. M. Randall; J. F. Meneses

1999-01-01

128

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

129

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)

2010-08-17

130

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

131

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

Microsoft Academic Search

Molecular theory of curved vapor-liquid interphase boundaries was considered in terms of the lattice gas model. The theory\\u000a uses the quasi-thermodynamic concept of curved layers of a separation boundary with a large radius. The transition from a\\u000a rectangular lattice to such layers is performed by the introduction of a variable number of the nearest neighbors. The problems\\u000a (1) of the

Yu. K. Tovbin

2010-01-01

132

Developments in centrifugal compressor surge control: A technology assessment  

Microsoft Academic Search

There are a number of surge control schemes in current use for centrifugal compressors employed in natural gas transmission systems. Basically, these schemes consist of a set of detection devices that either anticipate surge or detect it at its inception, and a set of control devices that act to prevent surge from occurring. A patent search was conducted in an

K. K. Botros; J. F. Henderson

1994-01-01

133

CENTRIFUGAL MEMBRANE FILTRATION  

SciTech Connect

SpinTek Membrane Systems, Inc., the developer of a centrifugal membrane filtration technology, has engineered and developed a system for use within the U.S. 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. SpinTek II High Shear Rotary Membrane Filtration System is a unique compact crossflow membrane system that has large, demonstrable advantages in performance and cost compared to currently available systems: (1) High fluid shear prevents membrane fouling even with very high solids content; hazardous and radioactive components can be concentrated to the consistency of a pasty slurry without fouling. (2) Induced turbulence and shear across the membrane increases membrane flux by a factor of ten over existing systems and allows operation on fluids not otherwise treatable. (3) Innovative ceramic membrane and mechanical sealing technology eliminates compatibility problems with aggressive DOE waste streams. (4) System design allows rapid, simple disassembly for inspection or complete decontamination. (5) Produces colloidal- and suspended-solids-free filtrate without the addition of chemicals. The first phase of this project (PRDA maturity stage 5) completed the physical scale-up of the SpinTek unit and verified successful scale-up with surrogate materials. Given successful scale-up and DOE concurrence, the second phase of this project (PRDA maturity stage 6) will provide for the installation and operation of the full-scale two-stage SpinTek unit for treatment of a DOE waste-stream at the Los Alamos National Laboratory. This technology has very broad application across the DOE system. Nineteen DOE technical needs areas (Appendix C) have been identified. Following successful full-scale demonstration for treatment of DOE wastes, this innovative technology will be rapidly deployed on a wide range of waste and process streams throughout the DOE system.

William A. Greene; Patricia A. Kirk; Richard Hayes; Joshua Riley

2005-10-28

134

Theory of heterogeneous decay of a gas-supersaturated solution on passive gas bubbles  

Microsoft Academic Search

It is shown that there can be barrierless heterogeneous nucleation of bubbles of a mixture of active and passive gases on bubbles of a passive gas in a solution supersaturated with active gas. The threshold solution supersaturation above which barrierless heterogeneous nucleation commences is found. All the thermodynamic data on heterogeneous formation of nucleating centers needed to describe the kinetics

F. M. Kuni; A. A. Melikhov

1993-01-01

135

Kinetic Theory and Rarefied Gas Dynamics: Book of Abstracts of All Russia Seminar.  

National Technical Information Service (NTIS)

This book contains the abstracts of papers presented at the All-Russia Seminar Kinetic Theory and Rarefied Gas Dynamics 2-6 December, 2002. The results of theoretical and experimental investigations on the following topics are given in the papers: kinetic...

A. K. Rebrov V. Y. Rudyak A. A. Belkin

2003-01-01

136

Theory of microwave-induced oscillations in the magnetoconductivity of a two-dimensional electron gas  

Microsoft Academic Search

We develop a theory of magneto-oscillations in the photoconductivity of a two-dimensional electron gas observed in recent experiments. The effect is governed by a change of the electron distribution function induced by the microwave radiation. We analyze a nonlinearity with respect to both the dc field and the microwave power, as well as the temperature dependence determined by the inelastic

I. A. Dmitriev; M. G. Vavilov; I. L. Aleiner; A. D. Mirlin; D. G. Polyakov

2005-01-01

137

Bimolecular gas-phase reactions in the Kramers theory of chemical kinetics @fa@f)  

Microsoft Academic Search

An expression for the rate constant is obtained for a bimolecular gas?phase reaction via an extended version of the Kramers theory of chemical kinetics. The multicomponent Fokker–Planck equation is transformed into a suitable set of relative coordinates that facilitated the derivation. The derived expression for the rate constant shows explicitly how the rate of reaction depends on the potential energy

R. S. Larson; M. D. Kostin

1984-01-01

138

Theory of gas hydrates: effect of the approximation of rigid water lattice.  

PubMed

One of the assumptions of the van der Waals and Platteeuw theory for gas hydrates is that the host water lattice is rigid and not distorted by the presence of guest molecules. In this work, we study the effect of this approximation on the triple-point lines of the gas hydrates. We calculate the triple-point lines of methane and ethane hydrates via Monte Carlo molecular simulations and compare the simulation results with the predictions of van der Waals and Platteeuw theory. Our study shows that even if the exact intermolecular potential between the guest molecules and water is known, the dissociation temperatures predicted by the theory are significantly higher. This has serious implications to the modeling of gas hydrate thermodynamics, and in spite of the several impressive efforts made toward obtaining an accurate description of intermolecular interactions in gas hydrates, the theory will suffer from the problem of robustness if the issue of movement of water molecules is not adequately addressed. PMID:21728316

Pimpalgaonkar, Hrushikesh; Veesam, Shivanand K; Punnathanam, Sudeep N

2011-07-29

139

Lattice gas model for enzyme kinetics (A correlated walks theory and variational procedures).  

National Technical Information Service (NTIS)

We have shown that by using a correlated walks theory or variational procedures, for the lattice gas model we can find for enzyme kinetics some new equations, which in the limit of no interactions between sites reduce to the classical Michaelis-Henri equa...

R. Mejdani

1989-01-01

140

Theory of inert gas-condensing vapor thermoacoustics: transport equations.  

PubMed

The preceding paper [J. Acoust. Soc. Am. 112, 1414-1422 (2002)] derives the propagation equation for sound in an inert gas-condensing vapor mixture in a wet-walled pore with an imposed temperature gradient. In this paper the mass, enthalpy, heat, and work transport equations necessary to describe the steady-state operation of a wet-walled thermoacoustic refrigerator are derived and presented in a form suitable for numerical evaluation. The requirement that the refrigerator operate in the steady state imposes zero mass flux for each species through a cross section. This in turn leads to the evaluation of the mass flux of vapor in the system. The vapor transport and heat transport are shown to work in parallel to produce additional cooling power in the wet refrigerator. An idealized calculation of the coefficient of performance (COP) of a wet-walled thermoacoustic refrigerator is derived and evaluated for a refrigeration system. The results of this calculation indicate that the wet-walled system can improve the performance of thermoacoustic refrigerators. Several experimental and practical questions and problems that must be addressed before a practical device can be designed and tested are described. PMID:12398450

Slaton, William V; Raspet, Richard; Hickey, Craig J; Hiller, Robert A

2002-10-01

141

Investigation of surge behavior in a micro centrifugal compressor  

NASA Astrophysics Data System (ADS)

This paper reports the experimental and theoretical study of the surge occurred in prototyping an ultra micro centrifugal compressor. As the first step, the 10 times size model of an ultra micro centrifugal compressor having the 40 mm outer diameter was designed and manufactured. The detailed experimental investigations for the transient behavior of surge with several different values of B parameter were carried out. The experimental results during the surge were compared with those obtained by the non-linear lumped parameter theory in order to validate the effectiveness of the theoretical surge model for the micro centrifugal compressor. As a result, the quite different behavior of the surge appeared for the different values of B both in the experiment and in the analysis.

Mizuki, Shimpei; Asaga, Yuichiro; Ono, Yushi; Tsujita, Hoshio

2006-06-01

142

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

143

Diffraction in low-energy electron scattering from DNA: Bridging gas-phase and solid-state theory  

Microsoft Academic Search

Using high-quality gas phase electron scattering calculations and multiple scattering theory, we attempt to gain insights into the radiation damage to DNA induced by secondary low-energy electrons in the condensed phase, and to bridge the existing gap with the gas phase theory and experiments. The origin of different resonant features (arising from single molecules or diffraction) is discussed and the

Laurent Caron; Léon Sanche; Stefano Tonzani; Chris H. Greene

2008-01-01

144

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

145

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

146

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

147

Open-cycle centrifugal vapor-compression heat pump. Final report, January 1986May 1987  

Microsoft Academic Search

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 and cost benefits of driving the compressor with a natural-gas-fueled gas-turbine engine. The turbine exhaust was

L. R. Burgmeier; J. E. Horner

1987-01-01

148

Non-equilibrium thermodynamics and kinetic theory of gas mixtures in the presence of interfaces.  

PubMed

A broad range of the boundary value problems of the kinetic theory of gases and gas mixtures is considered based on kinetic theory and non-equilibrium thermodynamics. The interrelation of the kinetic theory and non-equilibrium thermodynamics is discussed. The balance equations at the interface are obtained for the case of the boundary layers with peculiar properties. Procedures for deriving the boundary conditions for slightly rarefied gas mixtures are outlined. The problems of calculating slip coefficients are discussed. The specificity of the kinetic effects in the boundary conditions is shown. A set of general relations related to gas mixture flows in capillaries is deduced. The possibility of non-equilibrium kinetic effects in the form of a paradoxical distribution of non-equilibrium temperature is shown. Methods of non-equilibrium thermodynamics are used to obtain the phenomenological equations describing the thermophoresis and diffusiophoresis of particles and cross phenomena. The growth and evaporation of droplets is considered based on kinetic theory and non-equilibrium thermodynamics. PMID:12144096

Roldughi, V I; Zhdanov, V M

2002-06-10

149

Wave-driven plasma centrifuge  

NASA Astrophysics Data System (ADS)

A method for driving rotation in a fully ionized plasma centrifuge is described. The rotation is produced by radiofrequency waves near the cyclotron resonance. The wave energy is transferred into potential energy in a manner similar to the ? channeling effect. By driving the rotation using waves instead of electrodes, physical and engineering issues may be avoided.

Fetterman, Abraham; Fisch, Nathaniel

2009-11-01

150

CENTRIFUGAL DEWATERING OF FILTER CAKE  

Microsoft Academic Search

The dewatering of filter cake in a redundant Broadbent batch centrifuge was investigated. With some minor modifica- tions, the machine reduced the mass of the incoming cake feed by about 30 percent. At the same time approximately half the pol in the filter cake feed was recovered in the centrate return. The potential gains which could be realised from the

A. B. RAVN; G. R. E. LIONNET

151

Gasdynamics of a centrifugal machine  

Microsoft Academic Search

BS>Axisymmetric steady centrifugally driven thermal convection in a ; compressible fluid in a rapidly rotating circular cylinder is considered. The ; Doussinesq approximation is not used, because it is not valid for the case of ; praciical interest. The importance of the effect of the flow-induced volume ; change of a fluid particle is clarified, and a widely applicable method

Takeo Sakurai; Takuya Matsuda

1974-01-01

152

Centrifugal and torque responsive clutch  

Microsoft Academic Search

A coupling mechanism is described including a fluid coupling device with input and output elements, and a centrifugal type lock-up clutch for releasably engaging the input and output elements, characterized in that the lock-up clutch, this mechanism comprises: a cylindrical inner surface formed on the input element; a drive plate provided with friction elements displaceable in a radially outward direction

S. Sakakibara; S. Tsuzuki

1987-01-01

153

Experimental Investigation of Centrifugal Compressor Stabilization Techniques.  

National Technical Information Service (NTIS)

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 stabilizi...

G. J. Skoch

2003-01-01

154

High Stability Design for New Centrifugal Compressor.  

National Technical Information Service (NTIS)

It is essential that high-performance centrifugal compressors be free of subsynchronous vibrations. A new high-performance centrifugal compressor has been developed by applying the latest rotordynamics knowledge and design techniques: (1) To improve the s...

H. Kanki K. Katayama S. Morii Y. Mouri S. Umemura

1989-01-01

155

Gas Composition Effect on Centrifugal Compressor Performance  

Microsoft Academic Search

This paper was selected for presentation by the PSIG Board of Directors following review of information contained in an abstract submitted by the author(s). The material, as presented, does not necessarily reflect any position of the Pipeline Simulation Interest Group, its officers, or members. Papers presented at PSIG meetings are subject to publication review by Editorial Committees of the Pipeline

Sidney Pereira

2006-01-01

156

Theory of Bose-Einstein condensation in a microwave-driven interacting magnon gas.  

PubMed

Room temperature Bose-Einstein condensation (BEC) of magnons in YIG films under microwave driving has been recently reported. We present a theory for the interacting magnon gas driven out of equilibrium that provides rigorous support for the formation of the BEC. The theory relies on the cooperative mechanisms created by the nonlinear magnetic interactions and explains the spontaneous generation of quantum coherence and magnetic dynamic order when the microwave driving power exceeds a critical value. The results fit very well the experimental data for the intensity and the decay rate of Brillouin light scattering and for the microwave emission from the BEC as a function of driving power. PMID:21386417

Rezende, Sergio M

2010-03-30

157

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

158

Axial Segregation in a Cylindrical Centrifuge  

NASA Astrophysics Data System (ADS)

We propose a theory for axial segregation of suspensions of non-neutrally buoyant particles in a rotating cylinder. The cylinder is oriented in the horizontal plane, so that any axial forces must arise from interparticle interactions. We show that the hydrodynamic interaction between pairs of particles produces a relative motion in the axial direction, independent of the gravitational force. If the particles are denser than the suspending fluid, differential centrifuging between particles at different radial positions leads to an at­tractive interaction, inducing a rapid growth of axial density perturbations. We suggest that this mecha­nism can explain the origin of band formation in rotating suspensions of non-neutrally buoyant particles.

Lee, Jonghoon; Ladd, Anthony J.

2002-08-01

159

Axial segregation in a cylindrical centrifuge.  

PubMed

We propose a theory for axial segregation of suspensions of non-neutrally buoyant particles in a rotating cylinder. The cylinder is oriented in the horizontal plane, so that any axial forces must arise from interparticle interactions. We show that the hydrodynamic interaction between pairs of particles produces a relative motion in the axial direction, independent of the gravitational force. If the particles are denser than the suspending fluid, differential centrifuging between particles at different radial positions leads to an at-tractive interaction, inducing a rapid growth of axial density perturbations. We suggest that this mecha-nism can explain the origin of band formation in rotating suspensions of non-neutrally buoyant particles. PMID:12225195

Lee, Jonghoon; Ladd, Anthony J C

2002-08-14

160

Theory of the oscillatory photoconductivity of a 2D electron gas  

Microsoft Academic Search

We develop a theory of magnetooscillations in the photoconductivity of a\\u000atwo-dimensional electron gas observed in recent experiments. The effect is\\u000agoverned by a change of the electron distribution function induced by the\\u000amicrowave radiation. We analyze a nonlinearity with respect to both the dc\\u000afield and the microwave power, as well as the temperature dependence determined\\u000aby the inelastic

I. A. Dmitriev; M. G. Vavilov; I. L. Aleiner; A. D. Mirlin; D. G. Polyakov

2003-01-01

161

Theory of microwave-induced oscillations in the magnetoconductivity of a 2D electron gas  

Microsoft Academic Search

We develop a theory of magnetooscillations in the photoconductivity of a\\u000atwo-dimensional electron gas observed in recent experiments. The effect is\\u000agoverned by a change of the electron distribution function induced by the\\u000amicrowave radiation. We analyze a nonlinearity with respect to both the dc\\u000afield and the microwave power, as well as the temperature dependence determined\\u000aby the inelastic

I. A. Dmitriev; M. G. Vavilov; I. L. Aleiner; A. D. Mirlin; D. G. Polyakov

2004-01-01

162

Theory of the positive column in mercury rare-gas discharges  

Microsoft Academic Search

A detailed theory of the uniform positive column is developed for d.c. fluorescent lamp type discharges in mercury and rare-gas mixtures at 0.5 to 5 mmHg pressure, taking into account multi-stage excitation and ionization processes, using available cross section curves, the Ramsauer collision cross sections and imprisonment of the resonance radiation. The distributions of the ions, unexcited and excited atoms

M A Cayless

1963-01-01

163

Time dependent quantum mechanical theory of gas--surface energy transfer  

SciTech Connect

A fully quantum mechanical theory for phonon inelastic gas--surface scattering is presented. Both surface and bulk phonons are coupled to the molecule via perturbation theory. The reduced density matrix of the molecule is written in terms of three wave-function-like objects, which obey Schrodinger-like equations of motion. These highly coupled equations of motion are evolved simultaneously in time, using standard techniques. The method can be applied to any of several recent quantum and semiclassical time dependent scattering theories, and allows one to compute the thermally averaged properties of the system at all times. The total computational effort is only about three times that of the zero temperature calculation. Results are presented for the inelastic scattering of He and Ne beams from Cu(111), Cu(100), and Ni(111).

Jackson, B.

1988-01-15

164

Centrifugal separator devices, systems and related methods  

SciTech Connect

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

165

Performance of a centrifugal phytotron  

NASA Astrophysics Data System (ADS)

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 order to investigate the relationship between plant growth and increased gravity. This device enables us to cultivate plants over the long term by controlling environmental conditions in the phytotron such as temperature, relative humidity, CO_2 concentration and light intensity. The results of our experiment indicate that plant seeds can germinate and grow even under an artificial gravity which changes sinusoidally from 2G to 4G.

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

1996-01-01

166

When to maintain centrifugal pumps  

SciTech Connect

Centrifugal pumps comprise critical maintenance equipment. The rationale of when to maintain them relates to a spreading tendency to contain costs in the face of tight money. Plant managers are thus entitled to a thorough analysis of whether reduced expenditures truly lower costs or actually hinder maintenance and increase costs. Absence of such an analysis hides the fact that proper and timely maintenance has a double effect: it not only reduces power consumption but also extends equipment life, and thus reduces the frequency of labor and material expenditures for scheduled or crisis maintenance. Centrifugal pump maintenance can demonstrate well the validity of this observation. The paper discusses: restoring internal clearances; real cost of renewing clearances; and monitoring clearances and pump performance.

Karassik, I.J.

1993-04-01

167

Self-aligning centrifugal supports  

Microsoft Academic Search

A brief review of the basic types of rotation-type supports has been given. The structures of self-aligning gasdynamic and\\u000a hydrodynamic centrifugal supports have been described. A comparative computational analysis of their efficiency has been made;\\u000a the advantage of the hydraulic support in realizing large-tonnage processes has been shown on the basis of the analysis.

S. M. Arinkin; L. P. Panasenko; E. V. Papok

2009-01-01

168

Molecular Theory and Computer Simulation Studies of Natural and Synthetic Gas Mixtures. Final Report January 1, 1983-December 31, 1986.  

National Technical Information Service (NTIS)

Studies of bulk fluid mixtures and of liquid surface properties (liquid-gas and liquid-liquid) by statistical mechanical theories and computer simulation are reported. The authors have developed new theoretical equations of state for mixtures in which the...

K. E. Gubbins

1987-01-01

169

Molecular Theory and Computer Simulation Studies of Natural and Synthetic Gas Mixtures. Annual Report January 1, 1985-December 31, 1985.  

National Technical Information Service (NTIS)

Studies of bulk fluid mixtures and of liquid surface properties (liquid-gas and liquid-liquid) by statistical mechanical theories and computer simulation are reported. The authors have developed new theoretical equations of state for mixtures in which the...

K. E. Gubbins

1986-01-01

170

Information system for IAEA inspectors at a centrifuge enrichment plant  

SciTech Connect

An information system has been developed to aid International Atomic Energy Agency (IAEA) inspectors at the Portsmouth Gas Centrifuge Plant in the US. This system is designed to provide the inspectors with data storage, data analysis, and data evaluation and decision capabilities with minimal impact on the plant operations. The techniques and methodologies developed for this specific case are described with discussion of their general applicability to IAEA inspections at all types of facilities. 7 refs.

Baker, A.L.; Tape, J.W.; Picard, R.R.; Strittmatter, R.B.

1985-01-01

171

Diffraction in low-energy electron scattering from DNA: Bridging gas-phase and solid-state theory  

NASA Astrophysics Data System (ADS)

Using high-quality gas phase electron scattering calculations and multiple scattering theory, we attempt to gain insights into the radiation damage to DNA induced by secondary low-energy electrons in the condensed phase, and to bridge the existing gap with the gas phase theory and experiments. The origin of different resonant features (arising from single molecules or diffraction) is discussed and the calculations are compared to existing experiments in thin films.

Caron, Laurent; Sanche, Léon; Tonzani, Stefano; Greene, Chris H.

2008-10-01

172

Statistical-overlap theory of column switching in gas chromatography: applications to flavor and fragrance compounds.  

PubMed

First-column gas chromatograms (GCs) of hundreds of flavor and fragrance compounds, and second-column GCs of specific regions of these GCs, are predicted using thermodynamic databases in commercial software. A statistical-overlap theory of column switching with cryogenic focusing then is developed by mimicking the predicted GCs by two kinds of Monte Carlo simulations. In the first kind, a probability distribution is calculated for the number of compounds in a region of the first-column GC, based on the number of observed peaks in the region, the number of observed peaks in the second-column GC, and the retention-time distributions and breadths of single-component peaks in both GCs. In the second kind, criteria are established for the theory's application. The theory is applied to 12 regions of first-column GCs. The theory predicts the number of compounds in all of them and shows that separation rarely is complete in second-column GCs, when 10 or more compounds are transferred between columns. The theory also rationalizes the tedious search required to find good separation conditions by showing that column-switching gas chromatography with cryogenic focusing is inherently statistical. The number of peaks in the second-column GC can be greater than, less than, or equal to the number of peaks in the relevant region of the first-column GC, and the good conditions sought by researchers to substantially improve separation correspond to favorable "rolls of the dice" found only by trial and error. PMID:12038754

Samuel, Clint; Davis, Joe M

2002-05-15

173

Preliminary study of a centrifugal-flow singlet oxygen generator  

SciTech Connect

By using the concept of a high-pressure, gravity-independent singlet oxygen generator (SOG) proposed by Emanuel and based on the principle that a rotating fluid is capable of producing an enormous centrifugal force, a novel-type centrifugal-flow singlet oxygen generator (CFSOG) was designed and constructed. In this device, O{sub 2}({sup 1}{delta}) was generated in the reaction of gaseous Cl{sub 2} with a rotating basic hydrogen peroxide (BHP) liquid flow and then was removed from the BHP liquid phase by the centrifugal force. Meanwhile, the microdroplets formed during the Cl{sub 2}+BHP reaction were removed from the O{sub 2}({sup 1}{delta}) gas flow by the centrifugal force produced by the high-speed flow along an arc-shaped channel. Preliminary investigations showed that, because the specific reactive surface area of this SOG was noticeably larger than that of the jet-SOG normally used in current chemical oxygen-iodine lasers (COILs), the O{sub 2}({sup 1}{delta}) yield of {approx}60%, the O{sub 2}({sup 1}{delta}) partial pressure as high as 31 Torr, and chlorine utilisation higher than 96% were realised. Moreover, steady operation was obtained. (laser components)

Shi, W; Deng, L; Yang, H; Sha, G; Zhang, C [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (China)

2008-02-28

174

Performance of high pressure COIL with centrifugal bubble singlet oxygen generator  

NASA Astrophysics Data System (ADS)

A centrifugal bubbling SOG is a perspective source of oxygen at high pressure with high depletion of the BHP in the single burn dawn. The theoretical estimations show that at high centrifugal acceleration gas-liquid contact specific surface 30cm-1, frequency of the surface renewal can less than 10-3s and bubble rise velocity up to 500 cm/s be realized in the bubble SOG. The results of the measurements of O2(1?) yield, chlorine utilization and water fraction at the exit of the centrifugal bubble SOG are presented. A high O2(1?) yield and chlorine utilization higher than 90% have been obtained at chlorine gas loading up to 6 mmole/s per 1 cm2 of the bubbler surface. The ejector COIL powered by centrifugal bubbling SOG demonstrated ~25% of chemical efficiency with specific power 6 kW per 1 litre/s of the BHP volumetric rate.

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

2007-05-01

175

CENTRIFUGES  

DOEpatents

Damping bearings for use on the shafts of an ultracentrifuge were designed which are capable of passing through critical angular speeds. The shaft extending from one end of the rotor is journaled in fixed-plain bearings mounted on annular resilient shock-absorbing elements to dampen small vibrations. The shaft at the other end of the rotor is journaled in two damper-bearing assemblies which are so spaced on the shaft that a vibration node can at no time exist at both bearing assemblies. These bearings are similar to the other bearings except that the bearing housings are slidably mounted on the supporting structure for movement transverse to the rotational axis of the rotor.

Beams, J.W.; Snoddy, L.B.

1960-08-01

176

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

177

ORNL centrifuge pellet fueling system  

SciTech Connect

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 to 10 pellets per second. The experimental program that is under way combines repetitive pellet fueling with the ergodic divertor and pump limiters to establish and understand long-pulse plasmas in which the pellet fuel source is in balance with the particle exhaust. With lower hybrid current drive, pulse lengths of up to 2 min might be achieved. To prepare for these extended pulse lengths, the pellet source on the centrifuge will be extended to provide a 300- to 500-pellet capability. A similar system extended to steady-state pellet fabrication technology and designed for a radiation and tritium environment would be a candidate for a fueling system for the International Thermonuclear Experimental Reactor (ITER). Analysis of pellet-fueled ITER discharges using the WHIST code shows the potential for controlling the radial fuel deposition point to achieve the desired core density while maintaining the edge density and temperatures so as to minimize the diverter plate erosion. A centrifuge fueling system would have the capability of taking the D-T exhaust directly from the cryopumping systems, recondensing and purifying the fuel, and injecting the reconstituted pellets into the plasma, thereby minimizing the tritium inventory.

Foster, C.A.; Houlberg, W.A.; Gouge, M.J.; Grapperhaus, M.J.; Milora, S.L. (Oak Ridge National Lab., TN (United States)); Drawin, H.; Geraud, A.; Chatelier, M.; Gros, G. (CEA Centre d'Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France))

1992-01-01

178

ORNL centrifuge pellet fueling system  

SciTech Connect

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 to 10 pellets per second. The experimental program that is under way combines repetitive pellet fueling with the ergodic divertor and pump limiters to establish and understand long-pulse plasmas in which the pellet fuel source is in balance with the particle exhaust. With lower hybrid current drive, pulse lengths of up to 2 min might be achieved. To prepare for these extended pulse lengths, the pellet source on the centrifuge will be extended to provide a 300- to 500-pellet capability. A similar system extended to steady-state pellet fabrication technology and designed for a radiation and tritium environment would be a candidate for a fueling system for the International Thermonuclear Experimental Reactor (ITER). Analysis of pellet-fueled ITER discharges using the WHIST code shows the potential for controlling the radial fuel deposition point to achieve the desired core density while maintaining the edge density and temperatures so as to minimize the diverter plate erosion. A centrifuge fueling system would have the capability of taking the D-T exhaust directly from the cryopumping systems, recondensing and purifying the fuel, and injecting the reconstituted pellets into the plasma, thereby minimizing the tritium inventory.

Foster, C.A.; Houlberg, W.A.; Gouge, M.J.; Grapperhaus, M.J.; Milora, S.L. [Oak Ridge National Lab., TN (United States); Drawin, H.; Geraud, A.; Chatelier, M.; Gros, G. [CEA Centre d`Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France)

1992-11-01

179

Testing of pyrochemical centrifugal contactors  

SciTech Connect

A centrifugal contactor that performs oxidation and reduction exchange reactions between molten metals and salts at 500 degrees Centigrade has been tested successfully at Argonne National Laboratory (ANL). The design is based on contactors for aqueous- organic systems operation near room temperature. In tests to demonstrate the performance of the pyrocontactor, cadmium and LICl- KCl eutectic salt were the immiscible solvent phases, and rare earths were the distributing solutes. The tests showed that the pyrocontactor mixed and separated the phases well, with stage efficiencies approaching 99% at rotor speeds near 2700 rpm. The contactor ran smoothly and reliably over the entire range of speeds that was tested.

Chow, L.S.; Carls, E.L.; Basco, J.K.; Johnson, T.R.

1996-08-01

180

Density-functional theory of the trapped two-dimensional Fermi gas in the unitary regime  

SciTech Connect

A recent paper by T. Papenbrock [Phys. Rev. A 72, 041602(R) (2005)] suggests that a determination of the universal factor {xi}{sub 3D} for a harmonically trapped, unpolarized dilute Fermi gas in the unitary regime may be obtained within the framework of a simple density-functional theory (DFT). One of the key results of that work is an estimate for the universal factor {xi}{sub 3D}{approx_equal}0.54, which is within 20% of the generally accepted quantum Monte Carlo simulation value of {xi}{sub 3D}=0.44{+-}0.01. Motivated by this result, this report investigates the determination of the universal factor {xi}{sub 2D} for a two-dimensional trapped Fermi gas, and suggests that the simple DFT approach of Papenbrock provides an exact result of {xi}{sub 2D}=1 in two dimensions.

Zyl, Brandon P. van; Need, Melodie [Department of Physics, St. Francis Xavier University, Antigonish, Nova Scotia, B2G 2W5 (Canada); Hutchinson, D. A. W. [Jack Dodd Centre for Photonics and Ultra-Cold Atoms, Department of Physics, University of Otago, Dunedin (New Zealand); Laboratoire Kastler Brossel, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris Cedex 05 (France)

2007-08-15

181

High-speed cinematography of gas-tungsten arc welding: theory and application  

SciTech Connect

High-speed photo-instrumentation theory and application are reviewed, with particular emphasis on high-speed cinematography, for the engineer who has not acquired an extensive background in scientific photography. Camera systems, optics, timing system, lighting, photometric equipment, filters, and camera mounts are covered. Manufacturers and other resource material are listed in the Appendices. The properties and processing of photosensitive materials suitable for high-speed photography are reviewed, and selected film data are presented. Methods are described for both qualitative and quantitative film analysis. This technology is applied to the problem of analyzing plasma dynamics in a gas-tungsten welding arc.

Reynolds, L.D.; Key, J.F.

1981-06-01

182

Theory of the SrTiO3 surface state two-dimensional electron gas  

NASA Astrophysics Data System (ADS)

We present a theory of the quasi-two-dimensional electron gas (2DEG) systems that appear near the surface of SrTiO3 when a large external electric field attracts carriers to the surface. We find that nonlinear and nonlocal screening by the strongly polarizable SrTiO3 lattice plays an essential role in determining 2DEG properties. The electronic structure always includes weakly bound bulklike bands that extend over many SrTiO3 layers. At 2D carrier densities exceeding ˜1014cm-2, tightly bound bands emerge that are confined within a few layers of the surface.

Khalsa, Guru; MacDonald, A. H.

2012-09-01

183

Towards understanding proton affinity and gas-phase basicity with density functional reactivity theory  

NASA Astrophysics Data System (ADS)

The proton affinity and gas-phase basicity of 14 heterocyclic aromatic compounds containing two or more nitrogen atoms are investigated in this work. Strong linear correlations of these quantities with the molecular electrostatic potential on the nitrogen nuclei and natural valence orbital energies were observed. We justified the relationships under the framework of density functional reactivity theory as the first-order approximation. These linear relationships suggest that the associating proton prefers to bind with the basic atom with the lowest electrostatic potential value. Different density functional formulas and basis sets have been employed to verify the validity of these results.

Huang, Ying; Liu, Lianghong; Liu, Shubin

2012-02-01

184

Quantum corrections to the semiclassical Hartree-Fock theory of a harmonically trapped Bose gas  

NASA Astrophysics Data System (ADS)

Using the phase-space expansion of the thermodynamical distribution functions we provide a general and systematic method for including effects beyond the local-density approximation to the semiclassical Hartree-Fock theories. We illustrate the method by applying it to the case of a strictly two-dimensional, harmonically trapped Bose gas. Thereby, we address the ambiguous prediction of the Hartree-Fock approximation, namely, whether a fixed number of trapped atoms undergoes Bose-Einstein condensation or not. We also investigate the dependence of the critical temperature on the interaction strength.

Schumayer, D.; Cormack, S.; van Zyl, B. P.; Farry, J.; Collin, A.; Zaremba, E.; Hutchinson, D. A. W.

2012-08-01

185

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

NASA Astrophysics Data System (ADS)

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.

Eiroa, Ernesto F.; Figueroa Aguirre, Griselda

2012-11-01

186

Centrifugal separators and related devices and methods  

SciTech Connect

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

187

CFD simulation of centrifugal cells washers.  

PubMed

The feasibility of using computational fluid dynamics to guide the design of better centrifuges for processing shed blood is explored here. The velocity field and the rate of protein removal from the shed blood have been studied. The results indicate that computational fluid dynamics could help screen preliminary centrifuge bowl designs thus reducing the number of initial experimental tests required when developing new centrifuge bowls. Though the focus of this work is on washing shed blood the methods developed here are applicable to the design of centrifuge bowls for other blood processing applications. PMID:15133962

Kellet, Beth E; Binbing, Han; Dandy, David S; Wickramasinghe, S Ranil

2004-01-01

188

Solid deuterium centrifuge pellet injector  

SciTech Connect

Pellet injectors are needed to fuel long pulse tokamak plasmas and other magnetic confinement devices. For this purpose, an apparatus has been developed that forms 1.3-mm-diam pellets of frozen deuterium at a rate of 40 pellets per second and accelerates them to a speed of 1 km/s. Pellets are formed by extruding a billet of solidified deuterium through a 1.3-mm-diam nozzle at a speed of 5 cm/s. The extruding deuterium is chopped with a razor knife, forming 1.3-mm right circular cylinders of solid deuterium. The pellets are accelerated by synchronously injecting them into a high speed rotating arbor containing a guide track, which carries them from a point near the center of rotation to the periphery. The pellets leave the wheel after 150/sup 0/ of rotation at double the tip speed. The centrifuge is formed in the shape of a centrifugal catenary and is constructed of high strength KEVLAR/epoxy composite. This arbon has been spin-tested to a tip speed of 1 km/s.

Foster, C.A.

1982-01-01

189

FORCE2: A multidimensional flow program for gas solids flow theory guide  

SciTech Connect

This report describes the theory and structure of the FORCE2 flow program. The manual describes the governing model equations, solution procedure and their implementation in the computer program. FORCE2 is an extension of an existing B&V multidimensional, two-phase flow program. FORCE2 was developed for application to fluid beds by flow implementing a gas-solids modeling technology derived, in part, during a joint government -- industry research program, ``Erosion of FBC Heat Transfer Tubes,`` coordinated by Argonne National Laboratory. The development of FORCE2 was sponsored by ASEA-Babcock, an industry participant in this program. This manual is the principal documentation for the program theory and organization. Program usage and post-processing of code predictions with the FORCE2 post-processor are described in a companion report, FORCE2 -- A Multidimensional Flow Program for Fluid Beds, User`s Guide. This manual is segmented into sections to facilitate its usage. In section 2.0, the mass and momentum conservation principles, the basis for the code, are presented. In section 3.0, the constitutive relations used in modeling gas-solids hydrodynamics are given. The finite-difference model equations are derived in section 4.0 and the solution procedures described in sections 5.0 and 6.0. Finally, the implementation of the model equations and solution procedure in FORCE2 is described in section 7.0.

Burge, S.W.

1991-05-01

190

Continuum description of rarefied gas dynamics. I. Derivation from kinetic theory.  

PubMed

We describe an asymptotic procedure for deriving continuum equations from the kinetic theory of a simple gas. As in the works of Hilbert, of Chapman, and of Enskog, we expand in the mean flight time of the constituent particles of the gas, but we do not adopt the Chapman-Enskog device of simplifying the formulas at each order by using results from previous orders. In this way, we are able to derive a new set of fluid dynamical equations from kinetic theory, as we illustrate here for the relaxation model for monatomic gases. We obtain a stress tensor that contains a dynamical pressure term (or bulk viscosity) that is process dependent and our heat current depends on the gradients of both temperature and density. On account of these features, the equations apply to a greater range of Knudsen number (the ratio of mean free path to macroscopic scale) than do the Navier-Stokes equations, as we see in the accompanying paper. In the limit of vanishing Knudsen number, our equations reduce to the usual Navier-Stokes equations with no bulk viscosity. PMID:11690147

Chen, X; Rao, H; Spiegel, E A

2001-09-26

191

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

192

The simulation and performance of a centrifugal chiller  

NASA Astrophysics Data System (ADS)

A computer simulation model was developed to analyze the performance of a water-cooled centrifugal chiller. The model is based on a heat pump thermodynamic cycle and empirical correlations for the performance of the system components. The system simulated is composed of a variable-speed centrifugal compressor with a hot-gas bypass option for capacity control, two shell-and-tube heat exchangers, and an expansion device. The model was validated and calibrated against the experimental test results of a 125-ton chiller. The performance of a similar chiller system at various operating conditions and design modifications was analyzed. System performance comparisons were made between a baseline case, cases with high-performance heat exchanger tubes and compressor motor, and various variable-speed compressor operating strategies. It was found that significant performance improvement can be realized by using variable-speed drive and on-demand control strategy.

Jackson, W. L.; Chen, F. C.; Hwang, B. C.

193

Fouling reduction using centrifugal membrane separation  

Microsoft Academic Search

The effect of membrane orientation in a centrifugal membrane system (CMS) on the alleviation of fouling of reverse osmosis (RO) and nanofiltration (NF) membranes by colloidal foulants was examined. Colloidal silica fouling of RO membranes is dramatically reduced relative to a conventional reference system for all membrane orientations except (0, 180, 0) in which the centrifugal force is directed towards

T. M Fyles; D. S Lycon

2000-01-01

194

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

195

Analysis of centrifugal convection in rotating pipes  

Microsoft Academic Search

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

Vladimir Shtern; Valery Zimin; Fazle Hussain

2001-01-01

196

Phase field theory modeling of methane fluxes from exposed natural gas hydrate reservoirs  

NASA Astrophysics Data System (ADS)

Fluxes of methane from offshore natural gas hydrate into the oceans vary in intensity from massive bubble columns of natural gas all the way down to fluxes which are not visible within human eye resolution. The driving force for these fluxes is that methane hydrate is not stable towards nether minerals nor towards under saturated water. As such fluxes of methane from deep below hydrates zones may diffuse through fluid channels separating the hydrates from minerals surfaces and reach the seafloor. Additional hydrate fluxes from hydrates dissociating towards under saturated water will have different characteristics depending on the level of dynamics in the actual reservoirs. If the kinetic rate of hydrate dissociation is smaller than the mass transport rate of distributing released gas into the surrounding water through diffusion then hydrodynamics of bubble formation is not an issue and Phase Field Theory (PFT) simulations without hydrodynamics is expected to be adequate [1, 2]. In this work we present simulated results corresponding to thermodynamic conditions from a hydrate field offshore Norway and discuss these results with in situ observations. Observed fluxes are lower than what can be expected from hydrate dissociating and molecularly diffusing into the surrounding water. The PFT model was modified to account for the hydrodynamics. The modified model gave higher fluxes, but still lower than the observed in situ fluxes.

Kivelä, Pilvi-Helinä; Baig, Khuram; Qasim, Muhammad; Kvamme, Bjørn

2012-12-01

197

Warm up centrifugal pumps properly  

SciTech Connect

The design and operation of warmup systems is critical in preventing premature failure of centrifugal pumps in hot service. The simple warmup systems used in the past are not adequate to ensure an even heatup of the case and internals for the larger pumps (over 200 hp) in use today. A proper warmup reduces maintenance costs and improves pump reliability. This article provides the guidelines for the design and operation of appropriate warmup systems to the chemical engineer preparing the piping and instrument diagrams (P and IDs) and the plant operator. Most pump vendors will provide recommended warmup procedures for specific applications. However, the pump vendors are normally not selected when the P and IDs are being developed. This article tries to bridge this gap.

Woodside, O.W.

1996-01-01

198

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

199

Gas-phase reactions of pd with acetone: A theoretical investigation using density functional theory  

NASA Astrophysics Data System (ADS)

The gas-phase reaction of palladium atom with acetone is investigated using density functional theory. Geometries and energies of the reactants, intermediates, and products involved are calculated. Both ground and excited state potential energy surfaces are investigated in detail. The present results show that the title reaction start with the formation of an ?2-CH3COCH3-metal complex, followed by C-O, C-H, and C-C activation. These reactions can lead to four different products (PdO + C3H6, PdCH2COCH3 + H, PdCH2 + CH3CHO, and PdCOCH2 + CH4). The present results may be helpful in understanding the mechanism of the title reaction and further experimental investigation of the reaction.

Dai, Guo-Liang; Wang, Chuan-Feng

2012-12-01

200

Centrifugal pneumatic disintegration of melts  

Microsoft Academic Search

UDC 621.762.224 In the manufacture of metal powders extensive use is made of the pneumatic method [1] of atomizing melts with compressed gas streams. However, even at considerable specific rates of flow (--0.5--1 NTP m 3 per 1 kg of product) and high pressures (-1.5--2 MPa) of the gas (often an expensive inert gas which is in short supply) it

Sh. M. Sheikhaliev; O. A. Ivanov; S. A. Areshkin

1990-01-01

201

Shape separation of gold nanorods using centrifugation  

PubMed Central

We demonstrate the use of centrifugation for efficient separation of colloidal gold nanorods from a mixture of nanorods and nanospheres. We elucidate the hydrodynamic behavior of nanoparticles of various shapes and illustrate that the shape-dependent drag causes particles to have shape-dependent sedimentation behavior. During centrifugation, nanoparticles undergo Brownian motion under an external field and move with different sedimentation velocities dictated by their Svedberg coefficients. This effects a separation of particles of different shape and size. Our theoretical analysis and experiments demonstrate the viability of using centrifugation to shape-separate a mixture of colloidal particles.

Sharma, Vivek; Park, Kyoungweon; Srinivasarao, Mohan

2009-01-01

202

Experiment and Theory for the Thickness Effect of Nano Metal Oxide Gas Sensing Thin Film The Thickness Effect and Mesoscopic Theory of Conductance Activity Energy  

Microsoft Academic Search

The characteristics of conductance activity energy of SnO2 thin film varies with film thickness l and grain size r0 are given by experiment results. The cross-section current formula of porous materials and the conductance formula of gas sensing thin film with adsorbed oxygen negative ion are given. The mesoscopic theory of nano-thin film conductance activity energy was proposed, and using

Xing Jianping; Yuan Qinghua; Li Donghua; Lu Honglang; Qiu Nanwan

2006-01-01

203

Rotational instabilities and centrifugal hangup  

NASA Astrophysics Data System (ADS)

One interesting class of gravitational radiation sources includes rapidly rotating astrophysical objects that encounter dynamical instabilities. We have carried out a set of simulations of rotationally induced instabilities in differentially rotating polytropes. An n=1.5 polytrope with the Maclaurin rotation law will encounter the m=2 bar instability at T/(vert-bar)W(vert-bar) (ge) 0.27. Our results indicate that the remnant of this in-stability is a persistent bar-like structure that emits a long-lived gravitational radiation signal. Furthermore, dynamical instability is shown to occur in n=3.33 polytropes with the j-constant rotation law at T/(vert-bar)W(vert-bar) (ge) 0:14. In this case, the dominant mode of instability is m=1. Such instability may allow a centrifugally-hung core to begin collapsing to neutron star densities on a dynamical timescale. If it occurs in a supermassive star, it may produce gravitational radiation detectable by LISA.

New, K.; Centrella, J.

2000-12-01

204

Centrifuge advances using HTS magnetic bearings  

NASA Astrophysics Data System (ADS)

Passive magnetic bearings are of increasing technical interest. We performed experiments with centrifugal rotors to analyze gyroscopic forces in terms imbalance, rotor elasticity and damping. Centrifuge rotors need to be operated soft and stable without whirling the sediments. In order to evaluate optimal parameters critical and resonance behaviors are investigated. Eccentricities up 2 mm are safely passed by accelerating test wheels. In a simple model we describe the effect of passing critical rotational speeds. Measurements of bearing properties and wheel performance are presented. We have constructed a first prototype centrifuge designed with a HTS double bearing which operates a titanium rotor safely up to 30000 rpm. A 15 W Stirling cooler serves cryogenics of the YBCO stators. From the experiments design guidelines for centrifugal applications with HTS bearings are given.

Werfel, F. N.; Flögel-Delor, U.; Rothfeld, R.; Wippich, D.; Riedel, T.

2001-05-01

205

Centrifugal Distortion in Water and Hydrogen Sulfide.  

National Technical Information Service (NTIS)

It is the intent of this note to present specific results pertaining to the changes in molecular geometry of water and hydrogen sulfide which are induced by centrifugal effects in rotational states of the molecules. Hydrogen, deuterium, and tritium substi...

R. M. Garvey

1976-01-01

206

Unsteady Flow Phenomena in Centrifugal Turbomachinery.  

National Technical Information Service (NTIS)

The research is an experimental investigation of system dynamics, unsteady effects, and detailed flow instabilities in a centrifugal compressor. The surge line, which marks the onset of instability and hence limits the minimum stable operating regime, is ...

D. A. Fink

1986-01-01

207

Acoustic Similarity Law for Centrifugal Fans.  

National Technical Information Service (NTIS)

Acoustic similarity laws for fans were exerimentally verified. Three, dimensionally similar centrifugal fans of 140, 280 and 560 mm impeller diameter were used. The fans were connected to anechoically terminated discharge ducts. It is shown that the influ...

W. Neise B. Barsikow

1980-01-01

208

The optimum design on LRE centrifugal pumps  

NASA Astrophysics Data System (ADS)

A mathematical model for performance prediction of low-specific-speed (LRE) centrifugal pumps is presented. The predicted performance is shown to be in agreement with experimental results within three to four percent.

Zhu, Zuchao; Zhang, Guoqian; Sun, Jiren

1992-06-01

209

Evaluation of non-centrifuged dried plasma spots versus centrifuged and non-centrifuged plasma for determination of HIV-1 viral load.  

PubMed

Accurate viral load measurement in plasma specimens is subject to the transport conditions applied since the stability of HIV-1 RNA can be at risk. Also, except during the primary infection, HIV is unlikely to be free in circulation because most patients produce specific antibodies in the weeks following primary infection. This study evaluated non centrifuged dried plasma spots versus centrifuged and non centrifuged plasma in the determination of HIV-1 viral load. A total of 40 patients infected with HIV were bled and three groups of samples were prepared from each patient. The first group was centrifuged at 1500×g for 20min, the second was not centrifuged but left to sediment by gravity for up to 3h, and the third was for dried plasma spots prepared from the same non centrifuged plasma. HIV RNA quantitation in plasma and dried plasma spots was evaluated by the Pearson correlation and a T-test. The three groups yielded average viral loads of 58,249; 83,355 and 116,963 copies/ml for centrifuged, non centrifuged and dried plasma spot samples respectively. The correlation for centrifuged versus non centrifuged was R(2)=0.78, that of centrifuged and dried plasma spots was R(2)=0.72 and finally R(2)=0.81 between non centrifuged and dried plasma spot samples. A significant difference in viral load results of centrifuged and DPS samples prepared from non centrifuged plasma was observed. PMID:23422513

Mwebaza, S; Batamwita, R; Karamagi, Y; Mugasa, C; Namwanje, C; Mujuzi, G; Nanteza, A

2013-02-17

210

Lubrication free centrifugal compressor. Technical report  

SciTech Connect

This paper describes an effort to demonstrate the benefits of an innovative, lightweight, lubrication free centrifugal compressor that allows the use of environmentally sale alternate refrigerants with improved system efficiencies over current state-of-the-art technology. This effort couples the recently developed 3-D high efficiency centrifugal compressor and fabrication technologies with magnetic bearing technology and will then prove the performance, life and reliability of the compressor.

Gottschlich, J.M.; Scaringe, R.P.; Gui, F.

1994-04-22

211

Isolation of symbiotic dinoflagellates by centrifugal elutriation  

SciTech Connect

Centrifugal elutriation, a method combining centripetal liquid flow with centrifugal force, has been used to isolate symbiotic dinoflagellates from a cnidarian host. The elutriated cells were shown to be viable by photosynthetic incorporation of /sup 14/CO/sub 2/ and low release of photosynthetic products into the incubation medium. The level of contamination by clinging debris was low and by host solids was negligible.

Bird, A.E.; Quinn, R.J.

1986-01-01

212

Coriolis Effect on the Stability of Centrifugally Driven Convection in a Rotating Anisotropic Porous Layer Subjected to Gravity  

Microsoft Academic Search

We investigate natural convection in a fluid saturated rotating anisotropic porous layer subjected to centrifugal gravitational\\u000a and Coriolis body forces. The Darcy model (including the centrifugal, gravitational and Coriolis terms; and permeability anisotropy\\u000a effects) and a modified energy equation (including the effects of thermal anisotropy) is used in the current analysis. The\\u000a linear stability theory is used to evaluate the

Saneshan Govender

2007-01-01

213

Scalar susceptibilities and four-quark condensates in the meson gas within chiral perturbation theory  

NASA Astrophysics Data System (ADS)

We analyze the properties of four-quark condensates and scalar susceptibilities in the meson gas, within finite temperature chiral perturbation theory (ChPT). The breaking of the factorization hypothesis does not allow for a finite four-quark condensate and its use as an order parameter, except in the chiral limit. This is rigorously obtained within ChPT and is therefore a model-independent result. Factorization only holds formally in the large Nc limit and breaks up at finite temperature even in the chiral limit. Nevertheless, the factorization breaking terms are precisely those needed to yield a finite scalar susceptibility, deeply connected to chiral symmetry restoration. Actually, we provide the full result for the SU(3) quark condensate to next-to-next-to- leading order in ChPT, thus extending previous results to include kaon and eta interactions. This allows us to check the effect of those corrections compared to previous approaches and the uncertainties due to low-energy constants. We provide a detailed analysis of scalar susceptibilities in the SU(3) meson gas, including a comparison between the pure ChPT approach and the virial expansion, where the unitarization of pion scattering is crucial to achieve a more reliable prediction. Through the analysis of the interactions within this approach, we have found that the role of the ? resonance is largely canceled with the scalar isospin two-channel interaction, leaving the ?(770) as the main contribution. Special attention is paid to the evolution towards chiral restoration, as well as to the comparison with recent lattice analysis.

Gómez Nicola, A.; Peláez, J. R.; de Elvira, J. Ruiz

2013-01-01

214

Importance of centrifugal effects for the internal kink mode stability in toroidally rotating tokamak plasmas  

SciTech Connect

Analytical theory and two different magnetohydrodynamical stability codes are used in a study of the effects of toroidal plasma rotation on the stability of the ideal, internal kink mode in tokamaks. The focus of the paper is on the role that the centrifugal effects on the plasma equilibrium play for the stability of this mode, and results from one code where centrifugal effects are self-consistently included (CASTOR-FLOW) [E. Strumberger et al., Nucl. Fusion 45, 1156 (2005)] are compared with the results from another code where such effects are not taken into account (MISHKA-F) [I. T. Chapman et al., Phys. Plasmas 13, 062511 (2006)]. It is found that, even at rather modest flow speeds, the centrifugal effects are very important for the stability of the internal kink mode. While the results from the two codes can be quite similar for certain profiles in the plasma, completely opposite results are obtained for other profiles. A very good agreement between analytical theory and the numerical results are, both for inconsistent and consistent equilibria, found for plasmas with large aspect ratio. From the analytical theory, the distinctly different stability properties of equilibria with and without centrifugal effects included can be traced to the stabilizing effect of the geodesic acoustic mode (GAM) induced by the plasma rotation. This GAM exists solely as a consequence of the nonuniform plasma density and pressure created by the centrifugal force on the flux surfaces, and a stabilizing coupling of the internal kink instability to this mode cannot therefore take place if the centrifugal effects are not included in the equilibrium. In addition to the GAM stabilization, the effects of the radial profiles of the plasma density and rotation velocity are also found to be significant, and the importance of these effects increases with decreasing aspect ratio.

Wahlberg, C. [Department of Physics and Astronomy, EURATOM/VR Fusion Association, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden); Chapman, I. T. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom); Graves, J. P. [Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland)

2009-11-15

215

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

SciTech Connect

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. [Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Institute of Applied Physics, Russian Academy of Science, RU-603950 Nizhny Novgorod (Russian Federation); Kocharovsky, Vladimir V. [Institute of Applied Physics, Russian Academy of Science, RU-603950 Nizhny Novgorod (Russian Federation)

2010-03-15

216

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

217

A uranium enrichment monitor for surveillance of a small centrifuge cascade  

Microsoft Academic Search

An automatic, remotely controlled enrichment monitor based on a quadrupole mass spectrometer is described. This system was used to measure the uranium isotopic ratios in the product and feed streams of a small gas centrifuge cascade. The performance of the system under design conditions is illustrated with typical results. Several difficulties encountered during the study are discussed in the light

P. J. Evans; C. J. Rutherford

1989-01-01

218

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

219

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

220

Extracorporeal membrane oxygenator compatible with centrifugal blood pumps.  

PubMed

Coil-type silicone membrane oxygenators can only be used with roller blood pumps due to the resistance from the high blood flow. Therefore, during extracorporeal membrane oxygenation (ECMO) treatment, the combination of a roller pump and an oxygenator with a high blood flow resistance will induce severe hemolysis, which is a serious problem. A silicone rubber, hollow fiber membrane oxygenator that has a low blood flow resistance was developed and evaluated with centrifugal pumps. During in vitro tests, sufficient gas transfer was demonstrated with a blood flow less than 3 L/min. Blood flow resistance was 18 mm Hg at 1 L/min blood flow. This oxygenator module was combined with the Gyro C1E3 (Kyocera, Japan), and veno-arterial ECMO was established on a Dexter strain calf. An ex vivo experiment was performed for 3 days with stable gas performance and low blood flow resistance. The combination of this oxygenator and centrifugal pump may be advantageous to enhance biocompatibility and have less blood trauma characteristics. PMID:12406150

Motomura, Tadashi; Maeda, Tomohiro; Kawahito, Shinji; Matsui, Takahiro; Ichikawa, Seiji; Ishitoya, Hiroshi; Kawamura, Masaki; Nishimura, Ikuya; Shinohara, Toshiyuki; Oestmann, Daniel; Glueck, Julia; Kawaguchi, Yoichiro; Sato, Koshiro; Nosé, Yukihiko

2002-11-01

221

Convection driven by centrifugal bouyancy in a rotating annulus  

NASA Astrophysics Data System (ADS)

Drift rates and amplitudes of convection columns driven by centrifugal bouyancy in a cylindrical fluid annulus rotating about a vertical axis have been measured by thermistor probes. Conical top and bottom boundaries of the annular fluid region are responsible for the prograde Rossby wave like dynamics of the convection columns. A constant positive temperature difference between the outer and the inner cylindrical boundaries is generated by the circulation of thermostatically controled water. Mercury and water have been used as converting fluids. The measurements extend the earlier visual observations of Busse and Carrigan (1974) and provide quantitative data for an eventual comparison with nonlinear theories of thermal Rossby waves. The measured drift frequencies are in general agreement with linear theory. Of particular interest is the decline of the amplitude of convection with increasing Rayleigh number in a region beyond the onset of convection.

Azouni, M. A.; Bolton, E. W.; Busse, F. H.

222

Centrifugal Separation and Equilibration Dynamics in an Electron-Antiproton Plasma  

SciTech Connect

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.

Andresen, G. B.; Bowe, P. D.; Hangst, J. S. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Ashkezari, M. D.; Hayden, M. E. [Department of Physics, Simon Fraser University, Burnaby BC, V5A 1S6 (Canada); Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Bertsche, W.; Butler, E.; Charlton, M.; Deller, A.; Eriksson, S.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Cesar, C. L. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil); Friesen, T. [Department of Physics and Astronomy, University of Calgary, Calgary AB, T2N 1N4 (Canada)

2011-04-08

223

Mechanisms of flow through compressible porous beds in sedimentation, centrifugation, deliquoring, and ceramic processing  

SciTech Connect

The major topics covered in the investigation include: centrifugation; cake filtration; sedimentation and thickening; capillary suction operations; ceramics, slip casting; optimization studies; and wastewater. The research program was aimed at the specific areas of solid/liquid separation including sedimentation, thickening, cake filtration, centrifugation, expression, washing, deep-bed filtration, screening, and membrane separation. Unification of the theoretical approaches to the various solid/liquid separation operations was the principle objective of the research. Exploring new aspects of basic separation mechanisms, verification of theory with experiment, development of laboratory procedures for obtaining data for design, optimizing operational methods, and transferring the results to industry were part of the program.

NONE

1996-01-25

224

Attenuation and dispersion of compressional waves in fluid-filled porous rocks with partial gas saturation (White model). Part I. Biot theory  

Microsoft Academic Search

An exact theory of attenuation and dispersion of seismic waves in porous rocks containing spherical gas pockets (White model) is presented using the coupled equations of motion given by Biot. Assumptions made are (1) the acoustic wavelength is long with respect to the distance between gas pockets and their size, and (2) the gas pockets do not interact. Thus, the

N. C. Dutta; H. Ode

1979-01-01

225

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

226

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

227

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

228

Possible segregation caused by centrifugal titanium casting.  

PubMed

The possibility of the segregation under solidification process using a centrifugal casting machine was investigated using an electron probe microanalyzer with elemental distribution map, line analysis and quantitative analysis. When a very small quantity of platinum was added to local molten titanium during the casting process, macroscopic segregation was observed under conditions of density difference of 0.1 g/cm3 at the most, confirming that the centrifugal force of the casting machine is extremely strong. When a Ti-6Al-4V alloy was cast, however, no macroscopic segregation was observed. The centrifugal force of the casting machine examined in the present study hardly results in the body-force segregation in this titanium alloy. PMID:9550020

Watanabe, K; Okawa, S; Kanatani, M; Nakano, S; Miyakawa, O; Kobayashi, M

1996-12-01

229

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

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

26. 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. Once the molasses was separated from the sugar crystals it flowed through the spouts in the base of the centrifugals. The centrifugals' pulleys can be seen underneath the centrifugal. The centrifugal on the right has been reinforced with seven metal bands. The handles for the clutch mechanism are located above the centrifugal. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

230

Granulomatous variant of giant centrifugal miliaria profunda.  

PubMed

Two infants presented with multiple asymptomatic papules and geographic and annular plaques over the extensor aspect of the upper and lower extremities and trunk. Skin biopsy of both lesions showed plugged and hyperplastic dilated acrosryingia and deep dermal ducts, along with granulomatous inflammatory reaction. These lesions showed self-healing with complete resolution. A previous report described similar clinical and histopathologic features and labeled it giant centrifugal miliaria profunda. Because of the large granulomatous plaques and deep infiltrate, we propose that it was a granulomatous variant of giant centrifugal miliaria profunda. We report these cases for their rarity and self-healing nature. PMID:22276567

Doshi, Bhavana R; Mahajan, Sunanda; Kharkar, Vidya; Khopkar, Uday S

2012-01-26

231

Centrifugal force model for pedestrian dynamics.  

PubMed

In this paper, a centrifugal force model is developed for pedestrian dynamics. The effects of both the headway and the relative velocity among pedestrians are taken into account, which can be expressed by a "centrifugal force" term in dynamic equation. The jamming probability due to the arching at exits for crowd flows is provided. A quantitative analysis of the crowd flowing out of a hall shows that the average leaving time T is a function of the exit width W in negative power. The related simulation indicates that the proposed model is able to reproduce the self-organization phenomena of lane formation for sparse flows. PMID:16196649

Yu, W J; Chen, R; Dong, L Y; Dai, S Q

2005-08-12

232

The Economic Theory of Enhanced Natural Gas Service to the Industrial Sector.  

National Technical Information Service (NTIS)

Future United States natural gas demand depends on the quality of natural gas service to industrial users. This interim report synthesizes and develops rules by which the economic efficiency of various improvements may be analyzed. Specifically, the rules...

C. J. Cicchetti L. D. Kirsch R. Shaughnessy

1981-01-01

233

Similarity theory for the physical simulation of natural gas hydrate reservoir development  

Microsoft Academic Search

In order to apply physical simulation results to natural gas hydrate reservoir parameters to provide a theoretical framework for the design of a development plan, an analytical equation method was used to obtain the similarity criteria of natural gas hydrate reservoir development by physical simulation, based on a mathematical model of natural gas hydrate development. Given the approach of numerical

Yaping LIU; Yueming CHEN; Yuhu BAI; Shuxia LI

2010-01-01

234

Adsorption of binary gas mixtures in heterogeneous carbon predicted by density functional theory: on the formation of adsorption azeotropes.  

PubMed

Classical density functional theory (DFT) was used to predict the adsorption of nine different binary gas mixtures in a heterogeneous BPL activated carbon with a known pore size distribution (PSD) and in single, homogeneous, slit-shaped carbon pores of different sizes. By comparing the heterogeneous results with those obtained from the ideal adsorbed solution theory and with those obtained in the homogeneous carbon, it was determined that adsorption nonideality and adsorption azeotropes are caused by the coupled effects of differences in the molecular size of the components in a gas mixture and only slight differences in the pore sizes of a heterogeneous adsorbent. For many binary gas mixtures, selectivity was found to be a strong function of pore size. As the width of a homogeneous pore increases slightly, the selectivity for two different sized adsorbates may change from being greater than unity to less than unity. This change in selectivity can be accompanied by the formation of an adsorption azeotrope when this same binary mixture is adsorbed in a heterogeneous adsorbent with a PSD, like in BPL activated carbon. These results also showed that the selectivity exhibited by a heterogeneous adsorbent can be dominated by a small number of pores that are very selective toward one of the components in the gas mixture, leading to adsorption azeotrope formation in extreme cases. PMID:20712330

Ritter, James A; Pan, Huanhua; Balbuena, Perla B

2010-09-01

235

Solar wind flow about the terrestrial planets 2. Comparison with gas dynamic theory and implications for solar-planetary interactions  

SciTech Connect

This study utilizes gas dynamic calculations in conjunction with observational bow shock models to investigate the solar wind flow patterns about the terrestrial planets. Average dayside bow shock position could be predicted for the earth by theory with an error of only approx.2%, given the observed shape and location of the magnetopause. Accordingly, our findings confirm the validity of the single-fluid gas dynamic approximation for describing this major aspect of solar wind flow past the earth. Modeled using gas dynamic theory, the solar wind interactions with Venus and Mars exhibit very significant differences. At Mars the mean inferred altitude of the solar wind-obstacle interface varies from 510 km at the stagnation point to almost 1000 km near the terminator. The effective magnetic moment required to produce a magnetosphere of this size for average solar wind dynamic pressures and terrestrial-type internal current systems is 1.4 +- 0.6 x 10/sup 22/ G cm/sup 3/. Gas dynamic modeling of the January 21, 1972, Mars 3 and July 20, 1976, Viking 1 lander particles and fields observations supports the conclusion that the Martian obstacle to the solar wind lies at altitudes too high for it to be associated with only an ionospheric or atmospheric interaction. In contrast with Mars, our modeling of the Venus observations has found that the bow wave is closer to the planet than would be expected for a purely ionospheric obstacle. The subsolar width of the Venus ionosheath in the Venera and PVO measurements is only 60% and 90%, respectively, of that predicted by the gas dynamic model. This result is attributed to the presence of solar wind-neutral atmosphere interactions in the lower ionosheath that are not included in the gas dynamic code.

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

1983-01-01

236

Mass Transfer in 12-CM Centrifugal Contactors  

SciTech Connect

One eight-stage unit (8-pack) of centrifugal contactors was tested in both extraction and stripping modes. Efficiencies approaching 100 percent were obtained in both modes. The contactors were operated successfully at a wide range of combined flow rates, including the HEF conditions. This report discusses the results of that test.

Chesna, J.C.

2001-06-26

237

Flow characteristics of a centrifugal pump  

Microsoft Academic Search

Measurements of velocity have been obtained in a centrifugal pump in terms of angle-resolved values in the impeller passages, the volute, the inlet and exit ducts and are presented in absolute and relative frames. The pump comprised a radial flow impeller with four backswept blades and a single volute, and the working liquid had the same refractive index as the

C. H. Liu; C. Vafidis; J. H. Whitelaw

1994-01-01

238

Upgrading MSR performance with centrifugal separators  

Microsoft Academic Search

Moisture separator performance in nuclear plants has been inadequate in many cases, with the plant experiencing excessive outlet moisture content and mechanical degradation. Many of these problems are the result of the inherent disadvantages of inertial separators in the moisture separator reheaters (MSRs). Babcock and Wilcox believes that centrifugal separators, which have been used extensively in fossil and nuclear steam

E. L. Houchens; J. R. Parkinson; T. G. Stack

1985-01-01

239

Positive feedback stabilization of centrifugal compressor surge  

Microsoft Academic Search

Abstract Stable operation of axial and centrifugal compressors is limited towards low mass 1ows due to the occurrence of surge. The stable operating region can be enlarged by active control. In this study, we use a control valve which is fully closed in the desired operating point and only opens to stabilize the system around this point. As a result,

Frank Willems; W. P. M. H. Heemels; Bram de Jager; Anton A. Stoorvogel

2002-01-01

240

Dynamic centrifugal compressor model for system simulation  

Microsoft Academic Search

A dynamic model of a centrifugal compressor capable of system simulation in the virtual test bed (VTB) computational environment is presented. The model is based on first principles, i.e. the dynamic performance including the losses is determined from the compressor geometry and not from the experimentally determined characteristic performance curves. In this study, the compressor losses, such as incidence and

Wei Jiang; Jamil Khan; Roger A. Dougal

2006-01-01

241

Centrifugal compressor surge and speed control  

Microsoft Academic Search

Previous work on stabilization of compressor surge is extended to include control of the angular velocity of the compressor. A low-order centrifugal compressor model is presented, where the states are mass flow, pressure rise, and rotational speed of the spool. Energy transfer considerations are used to develop a compressor characteristic. In order to stabilize equilibria to the left of the

Jan Tommy Gravdahl; Olav Egeland

1999-01-01

242

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

243

Stabilization of unsteady convective flows by centrifugation  

Microsoft Academic Search

A liquid heated from below exhibits temperature fluctuations, characteristic of an unstable convection regime. When the liquid is placed in the acceleration field of a centrifuge, this convection regime is subjected to enhanced buoyancy, the Coriolis force and the acceleration gradient. Flow visualizations in water and temperature measurements in molten tin and molten germanium are presented, using the large arm

P. Williams; A. Chevy; S. Bobeche; M. Rodot

1994-01-01

244

Multiphase flow modeling in centrifugal partition chromatography  

Microsoft Academic Search

The separation efficiency in Centrifugal Partition Chromatography (CPC) depends on selection of a suitable biphasic solvent system (distribution ratio, selectivity factor, sample solubility) and is influenced by hydrodynamics in the chambers. Especially the stationary phase retention, the interfacial area for mass transfer and the flow pattern (backmixing) are important parameters. Their relationship with physical properties, operating parameters and chamber geometry

S. Adelmann; C. Schwienheer; G. Schembecker

2011-01-01

245

Centrifugal Pump (High Pressure) for Power Transmissions.  

National Technical Information Service (NTIS)

This report describes the analytical study, design, and experimental investigation of a four-stage centrifugal pump capable of 30 gpm flow at a pressure of 4000 psi when pumping hydraulic fluid at an inlet temperature of 600 F. The hydrodynamic analysis i...

P. Hildebrand T. Vodopia J. Sanders L. Nagyszalanczy

1966-01-01

246

Numerical simulation for a centrifugal heart pump  

Microsoft Academic Search

The primary focus of this work is to investigate unsteady flow simulations for an incompressible fluid. Computational codes are developed and applied for the purpose of analyzing the flow in a centrifugal heart pump, the Innovative Ventricular Assist System (IVAS) pump, which was developed by the Cleveland Clinic Foundation as a part of the National Institute of Health's artificial heart

Keiji Yano

1997-01-01

247

Differential white cell count by centrifugal microfluidics.  

SciTech Connect

We present a method for counting white blood cells that is uniquely compatible with centrifugation based microfluidics. Blood is deposited on top of one or more layers of density media within a microfluidic disk. Spinning the disk causes the cell populations within whole blood to settle through the media, reaching an equilibrium based on the density of each cell type. Separation and fluorescence measurement of cell types stained with a DNA dye is demonstrated using this technique. The integrated signal from bands of fluorescent microspheres is shown to be proportional to their initial concentration in suspension. Among the current generation of medical diagnostics are devices based on the principle of centrifuging a CD sized disk functionalized with microfluidics. These portable 'lab on a disk' devices are capable of conducting multiple assays directly from a blood sample, embodied by platforms developed by Gyros, Samsung, and Abaxis. [1,2] However, no centrifugal platform to date includes a differential white blood cell count, which is an important metric complimentary to diagnostic assays. Measuring the differential white blood cell count (the relative fraction of granulocytes, lymphocytes, and monocytes) is a standard medical diagnostic technique useful for identifying sepsis, leukemia, AIDS, radiation exposure, and a host of other conditions that affect the immune system. Several methods exist for measuring the relative white blood cell count including flow cytometry, electrical impedance, and visual identification from a stained drop of blood under a microscope. However, none of these methods is easily incorporated into a centrifugal microfluidic diagnostic platform.

Sommer, Gregory Jon; Tentori, Augusto M.; Schaff, Ulrich Y.

2010-07-01

248

Special Centrifugal Pumps for the Water Cycle.  

National Technical Information Service (NTIS)

There is a description of special centrifugal pumps for transporting mixtures of solid matter and water. There is an explanation of the type of stress and the wear mechanism. A detailed description is given of the hydraulic layout, high-wear components an...

1983-01-01

249

World Centrifugal Sugar Situation and Outlook.  

National Technical Information Service (NTIS)

World centrifugal sugar production for 1983/84 is estimated at 94.7 million metric tons (raw value), down 6% from the near-record production of the previous season but virtually unchanged from the Nov 1983 estimate. The decline reflects adverse growing co...

1984-01-01

250

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

251

Effects of Centrifugation on Gonadal and Adrenocortical Steroids in Rats.  

National Technical Information Service (NTIS)

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 pituita...

R. Kakihana J. C. Butte

1980-01-01

252

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

253

Fine Particle Flotation in a Centrifugal Force Field.  

National Technical Information Service (NTIS)

The effect of a centrifugal force field on hydrodynamic characteristics, flotation kinetics and separation behavior was examined. Flotation devices were designed that combine a centrifugal force field and flotation action in one apparatus. The relation be...

H. M. G. C. Tils

1990-01-01

254

Modeling Platform Dynamics and Physiological Response to Short Arm Centrifugation.  

National Technical Information Service (NTIS)

An analysis is presented for the operation of a short radius centrifuge on an orbiting platform. A review of literature confirms that such a centrifuge could be useful in ameliorating the effects of microgravity deconditioning of astronauts. Our analysis ...

D. J. Pancratz J. B. Bomar J. H. Raddin

1994-01-01

255

High Technology Centrifugal Compressor for Commercial Air Conditioning Systems  

SciTech Connect

R&D Dynamics, Bloomfield, CT in partnership with the State of Connecticut has been developing a high technology, oil-free, energy-efficient centrifugal compressor called CENVA for commercial air conditioning systems under a program funded by the US Department of Energy. The CENVA compressor applies the foil bearing technology used in all modern aircraft, civil and military, air conditioning systems. The CENVA compressor will enhance the efficiency of water and air cooled chillers, packaged roof top units, and other air conditioning systems by providing an 18% reduction in energy consumption in the unit capacity range of 25 to 350 tons of refrigeration The technical approach for CENVA involved the design and development of a high-speed, oil-free foil gas bearing-supported two-stage centrifugal compressor, CENVA encompassed the following high technologies, which are not currently utilized in commercial air conditioning systems: Foil gas bearings operating in HFC-134a; Efficient centrifugal impellers and diffusers; High speed motors and drives; and System integration of above technologies. Extensive design, development and testing efforts were carried out. Significant accomplishments achieved under this program are: (1) A total of 26 builds and over 200 tests were successfully completed with successively improved designs; (2) Use of foil gas bearings in refrigerant R134a was successfully proven; (3) A high speed, high power permanent magnet motor was developed; (4) An encoder was used for signal feedback between motor and controller. Due to temperature limitations of the encoder, the compressor could not operate at higher speed and in turn at higher pressure. In order to alleviate this problem a unique sensorless controller was developed; (5) This controller has successfully been tested as stand alone; however, it has not yet been integrated and tested as a system; (6) The compressor successfully operated at water cooled condensing temperatures Due to temperature limitations of the encoder, it could not be operated at air cooled condensing temperatures. (7) The two-stage impellers/diffusers worked well separately but combined did not match well.

Ruckes, John

2006-04-15

256

Hydraulic design, numerical simulation and BVF diagnosis of high efficiency centrifugal pump  

NASA Astrophysics Data System (ADS)

Under the Two-dimensional Flow Theory and the Velocity Coefficient Theory, a centrifugal-pump impeller has been designed, based on the parameters of IS150-125-250 centrifugal pump. And self-compiled programs have been used to complete the hydraulic design of the whole flow passage of centrifugal pump. The space bending and twisting characteristics of the design blade are more obvious. Then, numerical simulation is applied to the inner flow field of the two pumps using RANS (Reynolds Averaged N-S) Equation with a standard k-? two-equation turbulence model. The compare of the numerical simulation data of two centrifugal pumps, getting from 13 working points including design condition, shows that, the design pump has higher head and efficiency in the range of lower flow rate. Based on the numerical results of the inner flow of the design pump and model pump, the boundary vorticity flux (BVF) diagnostics has been used to analyze the BVF distribution of suction surface and pressure surface of two pumps. The result shows that, the BVF distribution of the design pump is more uniform and smooth, with smaller peak value.

Zhang, Y. X.; Chen, L.; Zhou, X.; Jiangand, C. W.; Su, M.

2012-11-01

257

Investigations of acidity and nucleophilicity of diphenyldithiophosphinate ligands using theory and gas-phase dissociation reactions  

SciTech Connect

Diphenyldithiophosphinate (DTP) ligands modified with electron-withdrawing trifluoromethyl (TFM) substitutents are of high interest because they have demonstrated potential for exceptional separation of Am3+ from lanthanide3+ cations. Specifically, the bis(ortho-TFM) (L1-) and (ortho-TFM)(meta-TFM) (L2-) derivatives have shown excellent separation selectivity, while the bis(meta-TFM) (L3)- and unmodified DTP (Lu-) did not. Factors responsible for selective coordination have been investigated using density functional theory (DFT) calculations in concert with competitive dissociation reactions in the gas phase. To evaluate the role of (DTP+H) acidity, density functional calculations were used to predict pKa values, which followed the trend of L3 < L2 < L1 < Lu. The order of the TFM-modified (DTP+H) acids was opposite of what would be expected based on the e--withdrawing effects of the TFM group, suggesting that secondary factors are influencing the pKa and nucleophilicity. The relative nucleophilicities of the DTP anions were evaluated by forming metal-mixed ligand complexes in a trapped ion mass spectrometer, and then fragmenting them using competitive collision induced dissociation. Relative to Na+, the unmodified Lu- anion was the strongest nucleophile. Comparing the TFM derivatives, the bis(ortho-TFM) derivative L1- was found to be the strongest nucleophile, while the bis(meta-TFM) L3- was the weakest, a trend consistent with the pKa calculations. DFT modeling of the Na+ complexes suggested that the elevated cation affinity of the L1- and L2- anions was due to donation of electron density from fluorine atoms to the metal center, which was occurring in rotational conformers where the TFM moiety was proximate to the Na+-dithiophosphinate group. Competitive dissociation experiments were performed with the dithiophosphinate anions complexed with europium nitrate species; ionic dissociation of these complexes always produced the TFM-modified dithiophosphinate anions, showing again that the unmodified Lu- was the strongest nucleophile. The Eu(III) nitrate complexes also underwent redox elimination of radical ligands; the tendency of the ligands to undergo oxidation and be eliminated as neutral radicals followed the same trend as the nucleophilicities for Na+, viz. Lu- > L1- > L2- > L3-.

Christopher M. Leavitt; Garold L. Gresham; Michael T. Benson; Jean-Jaques Gaumet; Dean Peterman; John Klaehn; Megan Moser; Frederic Aubriet; Michael J. Van Stipdonk; Gary S. Groenewold

2008-04-01

258

An experiment to test centrifugal confinement for fusion  

Microsoft Academic Search

The basic idea of centrifugal confinement is to use centrifugal forces from supersonic rotation to augment conventional magnetic confinement. Optimizing this “knob” results in a fusion device that features four advantages: steady state, no disruptions, superior cross-field confinement, and a simpler coil configuration. The idea rests on two prongs: first, centrifugal forces can confine plasmas to desired regions of shaped

R. F. Ellis; A. B. Hassam; S. Messer; B. R. Osborn

2001-01-01

259

An experiment to test centrifugal confinement for fusion  

Microsoft Academic Search

The basic idea of centrifugal confinement is to use centrifugal forces from supersonic rotation to augment conventional magnetic confinement. Optimizing this ``knob'' results in a fusion device that features four advantages: steady state, no disruptions, superior cross-field confinement, and a simpler coil configuration. The idea rests on two prongs: first, centrifugal forces can confine plasmas to desired regions of shaped

R. F. Ellis; A. B. Hassam; S. Messer; B. R. Osborn

2001-01-01

260

Numerical Research on Performance Prediction for Centrifugal Pumps  

Microsoft Academic Search

Performance prediction for centrifugal pumps is now mainly based on numerical calculation and most of the studies merely focus on one model. Therefore, the research results are not representative. To make an improvement of numerical calculation method and performance prediction for centrifugal pumps, performance of six centrifugal pump models at design flow rate and off design flow rates, whose specific

TAN Minggao; YUAN Shouqi; LIU Houlin; WANG Yong; WANG Kai

261

Preoxidation prior to gas carburizing: Theory and its effect on pyrowear ® 53 alloy  

Microsoft Academic Search

The absorption of carbon during gas carburizing of steel components is reviewed based on thermodynamic and kinetic considerations.\\u000a The effects of chromium and silicon on carbon absorption are reviewed based on the thermodynamics of passive film formation\\u000a in the presence of a carburizing gas. Finally, the merits associated with the use of preoxidation treatments prior to gas\\u000a carburizing are discussed

Michael L. Schmidt

1990-01-01

262

Hydrodynamic model for a vacuum arc operated with background gas: Theory and experimental validation  

SciTech Connect

A stationary, one-dimensional fluid model is presented to describe the interelectrode region of a nonfiltered vacuum arc operated with a background gas. The model includes the electron energy equation and the main elastic and inelastic atomic processes among metallic ions, electrons, and gas particles. To validate the model predictions an experimental study of the plasma-neutral gas structure, using a titanium (Ti) cathode and argon (Ar) as the background gas, is presented. The measured electron temperature and the experimental dependence on the pressure of neutral Ti and Ar spectroscopic emission lines are well reproduced, using a simple atomic model to interpret the plasma radiation emission.

Grondona, D.; Kelly, H.; Minotti, F.O. [Departamento de Fisica, Instituto de Fisica del Plasma (CONICET), Facultad de Ciencias Exactas y Naturales (UBA), Ciudad Universitaria Pabello'n I, 1428 Buenos Aires (Argentina)

2006-02-15

263

A Very Approximate Theory for Gas Transport in a Polymer Foam  

SciTech Connect

The author is involved with a project that requires calculation of the flow of gas through thin sheets of a flexible polymer foam. Essentially, the foam is a collection of interconnected spherical holes in the polymer matrix. When the material is made, its porosity is in the range of 60-70%. Initially, the sheets are roughly a millimeter thick. In the application, the sheets are compressed between solid surfaces so that their thickness is reduced to approximately 50-75% of the original (thereby reducing the porosity to as low as 20%). The project requires calculating gas transport in the longitudinal direction (in other words, parallel to the thin section of the sheets and perpendicular to the direction of compression). The transport calculations must be done in three different flow regimes. First, with gas pressures high enough so that the gas in the pores is in the continuum regime and thus the transport is governed by the usual equations for flow of a compressible gas in a porous medium. Second, with gas pressures low enough so that the flow is in the free molecular region. In the third regime, the foam is filled with a carrier gas (with pressure high enough to be in continuum) and the flow of interest is that of a small amount of an additional gas. In this third regime, the driving force is diffusion of the trace gas in the carrier.

Kirkpatrick, J.R.

1999-12-01

264

Contribution to the theory of the high compression ratio gas ejector with cylindrical mixing chamber  

Microsoft Academic Search

Ways of improving the operation of a gas ejector with a high compression ratio are investigated. The conditions for obtaining the maximal compression ratio at the critical operating regime of the gas ejector are studied theoretically and experimentally with account for mixing of the supersonic injecting and subsonic ejected streams ahead of the choking section. The principles for the rational

G. L. Grodzovskii

1968-01-01

265

Theory and Methodology Optimizing the natural gas supply mix of local distribution utilities 1  

Microsoft Academic Search

A large mixed-integer linear program (MILP) and a much smaller nonlinear programming (NLP) approximation of the MILP, involving simulation and response surface estimation via regression analysis, are proposed to solve the problem of the optimal selection of natural gas supply contracts by local gas distribution utilities. Each potential supply source is characterized by several price and nonprice parameters. Weather variability

Jean-Michel Guldmann; Fahui Wang

266

Piecewise continuous distribution function method in the theory of wave disturbances of inhomogeneous gas  

Microsoft Academic Search

The system of hydrodynamic-type equations for a stratified gas in gravity field is derived from BGK equation by method of piecewise continuous distribution function. The obtained system of the equations generalizes the Navier–Stokes one at arbitrary Knudsen numbers. The problem of a wave disturbance propagation in a rarefied gas is explored. The verification of the model is made for a

D. A. Vereshchagin; S. B. Leble; M. A. Solovchuk

2006-01-01

267

Piecewise continuous distribution function method in the theory of wave disturbances of inhomogeneous gas  

Microsoft Academic Search

The system of hydrodynamic-type equations for a stratified gas in gravity field is derived from BGK equation by method of piecewise continuous distribution function. The obtained system of the equations generalizes the Navier Stokes one at arbitrary Knudsen numbers. The problem of a wave disturbance propagation in a rarefied gas is explored. The verification of the model is made for

D. A. Vereshchagin; S. B. Leble; M. A. Solovchuk

2006-01-01

268

Theory for radiatively driven harmonic acoustic waves in a confined gas  

Microsoft Academic Search

A detailed theoretical study is made of radiatively driven acoustic waves inside a closed cylindrical tube. The formulation accounts for all the essential phenomena for a gas in vibrational equilibrium—namely, gas motion, longitudinal and radial viscous dissipation, longitudinal and radial heat conduction, and radiative transfer with spectral detail included. An approximate expression is derived for the pressure response. This solution

Gary T. Chapman; Dale L. Compton; Walter G. Vincenti

1973-01-01

269

A small centrifugal pump for circulating cryogenic helium  

SciTech Connect

A small centrifugal pump is described which has been developed to circulate supercritical helium through a test loop for superconducting magnets. The pump has a fully enclosed warm and which contains the adjustable speed brushless DC drive motor and self-acting bearings operating in helium gas. The drive and bearing system is designed to minimize contaimination to the circulating supercritical helium in the test loop. The performance data which have been obtained show that the pump operates very close to its design specifications. Additional tests are planned to provide a more complete range of performance data for the pump. Subsequent record discussion concerned the pump shaft and the efficiency of the heat leak to the heat station. Efficiency of at least 65% is attainable with this pump, including all heat leak.

Swift, W.; Sixsmith, H.

1982-01-01

270

Strongly interacting Bose gas: Nozières and Schmitt-Rink theory and beyond  

NASA Astrophysics Data System (ADS)

We calculate the critical temperature for Bose-Einstein condensation in a gas of bosonic atoms across a Feshbach resonance and show how medium effects at negative scattering lengths give rise to pairs reminiscent of the ones responsible for fermionic superfluidity. We find that the formation of pairs leads to a large suppression of the critical temperature. Within the formalism developed by Nozières and Schmitt-Rink, the gas appears mechanically stable throughout the entire crossover region, but when interactions between pairs are taken into account we show that the gas becomes unstable close to the critical temperature. We discuss prospects of observing these effects in a gas of ultracold C133s atoms where recent measurements indicate that the gas may be sufficiently long lived to explore the many-body physics around a Feshbach resonance.

Koetsier, Arnaud; Massignan, P.; Duine, R. A.; Stoof, H. T. C.

2009-06-01

271

Performance prediction of industrial centrifuges using scale-down models.  

PubMed

Computational fluid dynamics was used to model the high flow forces found in the feed zone of a multichamber-bowl centrifuge and reproduce these in a small, high-speed rotating disc device. Linking the device to scale-down centrifugation, permitted good estimation of the performance of various continuous-flow centrifuges (disc stack, multichamber bowl, CARR Powerfuge) for shear-sensitive protein precipitates. Critically, the ultra scale-down centrifugation process proved to be a much more accurate predictor of production multichamber-bowl performance than was the pilot centrifuge. PMID:14566553

Boychyn, M; Yim, S S S; Bulmer, M; More, J; Bracewell, D G; Hoare, M

2003-10-18

272

Radial loads and axial thrusts on centrifugal pumps  

SciTech Connect

The proceedings of a seminar organised by the Power Industries Division of the IMechE are presented in this text. Complete contents: Review of parameters influencing hydraulic forces on centrifugal impellers; The effect of fluid forces at various operation conditions on the vibrations of vertical turbine pumps; A review of the pump rotor axial equilibrium problem - some case studies; Dynamic hydraulic loading on a centrifugal pump impeller; Experimental research on axial thrust loads of double suction centrifugal pumps; A comparison of pressure distribution and radial loads on centrifugal pumps; A theoretical and experimental investigation of axial thrusts within a multi-stage centrifugal pump.

Not Available

1986-01-01

273

Interpretation of results from well testing gas-condensate reservoirs: Comparison of theory and field cases  

SciTech Connect

A more complete understanding of well test interpretation results for gas-condensate fields may depend significantly on the availability of sufficient, accurate and specific field correlations involving fluid and rock properties, and on flow meter surveys. Apart from compositional variations, the most useful parameters in reviewing gas-condensate samples are condensate-gas ratio, dewpoint pressure and gas gravity. Pressure data recorded by quartz crystal gauges can result in gas gradients with sufficient accuracy to confirm variations in gas composition with depth for a reservoir of several hundred metres in thickness. By comparing these gradients with gas gravities from fluid samples, variation of the initial dewpoint pressure with depth was established. Special core analysis was carried out/sup +/ to obtain specific high velocity ..beta..-factors. However, when these laboratory measurements are compared with results obtained from production test analysis, large discrepancies are found in most cases, which can be attributed to multiphase flow near the wellbore. Although wellstream composition is found to be a function of rate, the presence of a stable condensate bank appears to be unfounded.

Behrenbruch, P.; Kozma, G.

1984-09-01

274

A centrifugal pump used as a turbine  

SciTech Connect

Due to the high cost of putting up conventional turbines for micro-hydropower installations, Inversin (1986) mentioned the use of pumps being run in reverse to function as turbines. Typical performance characteristics of a centrifugal pump running as a turbine are shown in a figure. Pump/turbine maximum efficiencies tend to occur over a wide range of capacity. This study is concerned with the use of non-conventional hydro equipment, locally and readily available for small rural electricity applications. Here, the operation of a small centrifugal pump, used as a turbine and coupled with a conventional car alternator, was investigated. The article reveals a method for evaluating not only this but other small generating systems for appropriateness to the conditions of the site.

Yap, F.U.; Lasnier, F. (Asian Institute of Technology, Bangkok (Thailand))

1990-06-01

275

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.

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

2011-01-01

276

Optimum design for LRE centrifugal pumps  

NASA Astrophysics Data System (ADS)

We set up a mathematical model to predict low specific speed liquid rocket engine (LRE) centrifugal pump unit performance. Using the model in question, performance predictions were carried out for 10 types of LRE centrifugal pumps. Relative errors between experimental values and predicted values associated with efficiency and lift were all within 4%. Using the model in question, design optimization with efficiency as the target function was carried out on AM-7H and O pumps as well as AM-1R pumps and AM-50 pumps. Results clearly show that, with a presupposition of surety systems possessing high vapor corrosion characteristics, the efficiencies of these four types of pumps can be respectively raised 6.5%, 5.22%, 5.2%, and 4.41%.

Zhu, Zuchao; Zhang, Guoqian; Sun, Jiren

1995-05-01

277

A vibration model for centrifugal contactors  

SciTech Connect

Using the transfer matrix method, we created the Excel worksheet ``Beam`` for analyzing vibrations in centrifugal contactors. With this worksheet, a user can calculate the first natural frequency of the motor/rotor system for a centrifugal contactor. We determined a typical value for the bearing stiffness (k{sub B}) of a motor after measuring the k{sub B} value for three different motors. The k{sub B} value is an important parameter in this model, but it is not normally available for motors. The assumptions that we made in creating the Beam worksheet were verified by comparing the calculated results with those from a VAX computer program, BEAM IV. The Beam worksheet was applied to several contactor designs for which we have experimental data and found to work well.

Leonard, R.A.; Wasserman, M.O.; Wygmans, D.G.

1992-11-01

278

Spaceborne centrifugal relays for spacecraft propulsion  

NASA Astrophysics Data System (ADS)

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

279

Transport Phenomena in Zonal Centrifuge Rotors  

PubMed Central

Zonal centrifuges may be loaded during rotation (dynamically) or at rest (statically). In the latter case, the shearing forces occurring in a liquid confined in a closed cylinder, during the transition from rest to a stable orientation in a high centrifugal force field, were examined qualitatively by evaluating the change of surfaces in each isodense layer. Analytical expressions for isodense surfaces at various levels were obtained as a function of the rotational speeds. Characteristics of the changes of each isodense layer were computed from the formula derived and are presented, in a graphical form, as figures. From these results, an optimal sample-loading location and an ideal control of acceleration or deceleration in a reorienting gradient rotor are concluded.

Hsu, H. W.; Anderson, N. G.

1969-01-01

280

Self-Energy Revision Operator Theory for the Many-Body Problem:. Application to Dynamical Properties of the Electron Gas  

NASA Astrophysics Data System (ADS)

An approximation scheme is proposed for implementing the algorithm to obtain the exact self-energy in the many-body problem [Phys. Rev. B52, 12708 (1995)]. This scheme relates the self-energy revision operator F, the key quantity in the algorithm, with fxc(q,?) the frequency-dependent exchange-correlation kernel appearing in the time-dependent density functional theory. We illustrate this scheme by applying it to the calculation of dynamic properties of the electron gas at metallic densities.

Takada, Yasutami

281

Wave-driven countercurrent plasma centrifuge  

NASA Astrophysics Data System (ADS)

A method for driving rotation and a countercurrent flow in a fully ionized plasma centrifuge is described. The rotation is produced by radiofrequency waves near the cyclotron resonance. The wave energy is transferred into potential energy in a manner similar to the ? channeling effect. The countercurrent flow may also be driven by radiofrequency waves. By driving both the rotation and the flow pattern using waves instead of electrodes, physical and engineering issues may be avoided.

Fetterman, Abraham J.; Fisch, Nathaniel J.

2009-11-01

282

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

283

Wave-driven Countercurrent Plasma Centrifuge  

SciTech Connect

A method for driving rotation and a countercurrent flow in a fully ionized plasma centrifuge is described. The rotation is produced by radiofrequency waves near the cyclotron resonance. The wave energy is transferred into potential energy in a manner similar to the ? channeling effect. The countercurrent flow may also be driven by radiofrequency waves. By driving both the rotation and the flow pattern using waves instead of electrodes, physical and engineering issues may be avoided.

A.J. Fetterman and N.J. Fisch

2009-03-20

284

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

285

The Application of Centrifuges 'Reduced Gravity' Research.  

NASA Astrophysics Data System (ADS)

It is shown that life has emerged on Earth somewhere in the early Archaean (3800-2500 million years ago). Since then life has evolved from single cell into to multicellular complex organism under unit gravity conditions. Little is known about how life would have been evolved under different gravity conditions. In light of the current quests for Earth-like planets by astronomers; what life forms could be expected on planets with different gravity fields? Also the human endeavors in spaceflight (microgravity) and exploration programs (Moon, Mars) it is interesting and might be even vital to know and understand how gravity acts upon the human body in long duration space flights. Hyper-gravity, any acceleration acceding 9.81 ms-2, can relatively easily be generated on Earth using centrifuges. Long duration hypo-gravity (¡9.81 ms-2) is more cumbersome. For real microgravity we need free falling satellites such as ISS. For simulation on ground one can use clinostats, random positioning machines or levitating magnets. But could centrifuges also be applied to study a reduced gravity environment? What I would explore in this paper are the possibilities how centrifuges could be applied to study the effects of a 'reduced gravity environment' in, especially, life sciences studies.

van Loon, Jack J. W. A.

286

Research opportunities with the Centrifuge Facility  

NASA Astrophysics Data System (ADS)

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.

287

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.

Tran, Susan L.; Welte, Michael A.

2010-01-01

288

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

289

Mechanisms of flow through compressible porous beds in sedimentation, filtration, centrifugation, deliquoring, and ceramic processing  

Microsoft Academic Search

The University of Houston research program is aimed at the specific area of solid\\/liquid separation including sedimentation, thickening, cake filtration, centrifugation, expression, washing, deep-bed filtration, screening, and membrane separation. Unification of the theoretical approaches to the various solid\\/liquid separation operations is the principle objective of the research. Exploring new aspects of basic separation mechanisms, verification of theory with experiment, development

Tiller

1992-01-01

290

Physical bases for the design of highly efficient rotors in centrifugal pumps  

Microsoft Academic Search

Conclusions  \\u000a1. \\u000aExisting notions concerning optimum (less than 40°) angles of blade inclination in the rotors of centrifugal pumps at the outlet from the rotor are based on experimental results. Analysis of the theory and experimental data indicated that the shapes of blades of one-sided curvature, which bend gradually rearward, are not optimal. A new blade profile featuring double curvature

P. R. Khlopenkov

1979-01-01

291

Contact time during impact of a spherical particle against a plane gas-liquid interface: theory  

Microsoft Academic Search

Bubble-particle impact in flotation is usually approximated to the particle approaching against a plane gas-liquid interface. In this paper we theoretically re-investigate this interaction and deal with its non-linear problems.It is evident that the restoring force is a non-linear ‘mixed’ function of the transition angle and the maximum depth of the deformed gas-liquid interface. This ‘mixed’ expression makes analytical prediction

A. V. Nguyen; H. J. Schulze; H. Stechemesser; G. Zobel

1997-01-01

292

Piecewise continuous partition function method in the theory of wave perturbations of inhomogeneous gas  

Microsoft Academic Search

The problem of wave disturbance propagation in rarefied gas in gravity field\\u000ais explored. The system of hydrodynamic-type equations for a stratified gas in\\u000agravity field is derived from BGK equation by method of piecewise continuous\\u000apartition function. The obtained system of the equations generalizes the\\u000aNavier-Stokes at arbitrary density (Knudsen numbers). The verification of the\\u000amodel is made for

D. A. Vereshchagin; S. B. Leble; M. A. Solovchuk

2004-01-01

293

Average charge states of heavy and superheavy ions passing through a rarified gas: Theory and experiment  

NASA Astrophysics Data System (ADS)

The average charge states q¯ of heavy and superheavy ions (atomic numbers Z=80–114) passing through He gas are studied experimentally and theoretically. Experimental data were measured at the gas-filled recoil separator, i.e., the TransActinide Separator and Chemistry Apparatus (TASCA) at GSI Darmstadt, for ion energies of a few hundred keV/u at gas pressures of 0.2 to 2.0 mbar. An attempt is made to describe experimental q¯ values by means of atomic calculations of the binding energies and electron-loss and electron-capture cross sections. The influence of the gas-density effect is included in the calculations. The calculated q¯ reproduce the experimental values for elements with Z=80–114 within 20%. A comparison with different semiempirical models is presented as well, including a local fit of high accuracy, which is often used in superheavy-element experiments to estimate the average charge states of heavy ions, e.g., at the gas-filled recoil separator TASCA. The q¯ values for elements with Z=115, 117, 119, and 120 at He-gas pressure of 0.8 mbar are predicted.

Khuyagbaatar, J.; Shevelko, V. P.; Borschevsky, A.; Düllmann, Ch. E.; Tolstikhina, I. Yu.; Yakushev, A.

2013-10-01

294

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

295

Theory, Theory  

NSDL National Science Digital Library

This lesson includes a theory-evaluation activity. A set of five scenarios (theories for how diverse life came into existence on Earth) is divided evenly throughout the class, so each student is asked to evaluate one theory. Students then come together in groups of five, so that all theories are represented in each group, where they are compared and evaluated. Each group reports to the entire class for further discussion and clarifications.

Kimmel, Michael

2007-12-12

296

Quantum field theory for the three-body constrained lattice Bose gas. I. Formal developments  

SciTech Connect

We develop a quantum field theoretical framework to analytically study the three-body constrained Bose-Hubbard model beyond mean field and noninteracting spin wave approximations. It is based on an exact mapping of the constrained model to a theory with two coupled bosonic degrees of freedom with polynomial interactions, which have a natural interpretation as single particles and two-particle states. The procedure can be seen as a proper quantization of the Gutzwiller mean field theory. The theory is conveniently evaluated in the framework of the quantum effective action, for which the usual symmetry principles are now supplemented with a ''constraint principle'' operative on short distances. We test the theory via investigation of scattering properties of few particles in the limit of vanishing density, and we address the complementary problem in the limit of maximum filling, where the low-lying excitations are holes and diholes on top of the constraint-induced insulator. This is the first of a sequence of two papers. The application of the formalism to the many-body problem, which can be realized with atoms in optical lattices with strong three-body loss, is performed in a related work [S. Diehl, M. Baranov, A. Daley, and P. Zoller, Phys. Rev. B 82, 064510 (2010)].

Diehl, S.; Daley, A. J.; Zoller, P. [Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, A-6020 Innsbruck (Austria); Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Baranov, M. [Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, A-6020 Innsbruck (Austria); Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); RRC 'Kurchatov Institute', Kurchatov Square 1, 123182 Moscow (Russian Federation)

2010-08-01

297

Analysis of Adsorption Data of Graphitized Thermal Carbon Black with a DFT-Lattice Gas Theory  

Microsoft Academic Search

In this paper we analyzed the adsorption of gases and vapors on graphitised thermal carbon black by using a modified DFT-lattice theory, in which we assume that the behavior of the first layer in the adsorption film is different from those of second and higher layers. The effects of various parameters on the topology of the adsorption isotherm were first

D. D. Do; H. D. Do

2002-01-01

298

Gravitational and centrifugal quantum states of neutrons  

NASA Astrophysics Data System (ADS)

Two related physical phenomena have recently been observed: quantum states of neutrons in the gravitational field above a flat mirror, and quantum states of neutrons in an effective centrifugal potential in the vicinity of a concave mirror. It is curious that the measurement of the near-surface quantum states of these two types is the first direct demonstration of the weak equivalence principle for a massive object in a quantum state. These two phenomena and their application to various domains of science will be explored using a new GRANIT spectrometer, which is under commissioning in the Institut Laue-Langevin, Grenoble, France. Most recent advances in these domains are mentioned.

Nesvizhevsky, V. V.; GRANIT Collaboration

2011-07-01

299

Centrifuge Modeling of Rainfall Induced Slope Failure  

NASA Astrophysics Data System (ADS)

Rainfall induces slope failure and debris flow which are considered as one of the major natural disasters. The scope of such failure is very large and it cannot be studied easily in the laboratory. Traditionally, small scale model tests are used to study such problem. Knowing that the behavior of soil is affected by the stress level, centrifuge modeling technique has been used to simulate more realistically full scale earth structures. In this study, two series of tests were conducted on slopes under the centrifugal field with and without the presence of rainfall. The soil used was a mixture of sand and 15 percent fines. The slopes of angle 60 degrees were prepared at optimum water content in order to achieve the maximum density. In the first series of tests, three different slope heights of 10 cm, 15 cm and 20 cm were used. The gravity was increased gradually until slope failure in order to obtain the prototype failure height. The slope model was cut after the test in order to obtain the configuration of failure surface. It was found that the slope geometry normalized by the height at failure provided unique results. Knowing the slope height or gravity at failure, the second series of tests with rainfall were conducted slightly below the critical height. That is, after attaining the desired gravity, the rainfall was induced in the centrifuge. Special nozzles were used and calibrated against different levels of gravity in order to obtain desired rainfall intensity. Five different rainfall intensities were used on the 15-cm slopes at 80g and 60g, which corresponded to 12 m and 9 m slope height, respectively. The duration until failure for different rainfall intensities was obtained. Similar to the first series of tests, the slope model was cut and investigated after the test. The results showed that the failure surface was not significantly affected by the rainfall. That is, the excess pore pressure induced by rainfall generated slope failure. The prediction curves of rainfall intensity versus duration were obtained from the test results. Such curves are extremely useful for disaster management. This study indicated feasibilities of using centrifuge modeling technique in simulating rainfall induced slope failure. The results obtained may also be used for validating numerical tools.

Ling, H.; Wu, M.

2006-12-01

300

Anion-exchange displacement centrifugal partition chromatography.  

PubMed

Ion-exchange displacement chromatography has been adapted to centrifugal partition chromatography. The use of an ionic liquid, benzalkonium chloride, as a strong anion-exchanger has proven to be efficient for the preparative separation of phenolic acid regioisomers. Multigram quantities of a mixture of three hydroxycinnamic acid isomers were separated using iodide as a displacer. The displacement process was characterized by a trapezoidal profile of analyte concentration in the eluate with narrow transition zones. By taking advantage of the partition rules involved in support-free liquid-liquid chromatography, a numerical separation model is proposed as a tool for preliminary process validation and further optimization. PMID:15516108

Maciuk, Alexandre; Renault, Jean-Hugues; Margraff, Rodolphe; Trébuchet, Philippe; Zèches-Hanrot, Monique; Nuzillard, Jean-Marc

2004-11-01

301

The Self-Enforcing Provisions of Oil and Gas Unit Operating Agreements: Theory and Evidence  

Microsoft Academic Search

This paper extends the existing theory and empirical investigation of unitization contracts. It highlights the importance of incentive-compatibility and self-enforcement and the bargaining problems faced in achieving viable, long-term contracts. We argue that only if the parties to a unitization contract have unit production shares that are the same as their cost shares will the contract be incentive compatible. Using

Gary D. Libecap; James L. Smith

1999-01-01

302

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.

303

November IAEA Report: Centrifuge File Not Closed; Natanz Enrichment Expands  

Microsoft Academic Search

Status of the Workplan: The IAEA outlined its discussions with Iran on the history of its P1 and P2 centrifuge programs. The P1 centrifuge is currently installed at the Fuel Enrichment Plant (FEP) at Natanz. Iran is undertaking research and development (R&D) on a variant of the P2, a faster, more advanced centrifuge, and has apparently started mechanical testing of

David Albright; Jacqueline Shire

2007-01-01

304

Semiempirical theory of Carver rates in alkali\\/noble-gas systems  

Microsoft Academic Search

During an encounter between a noble-gas atom and an alkali-metal atom, the electron density at the alkali nucleus is altered, resulting in a collisional change in the alkali's hyperfine coupling (i.e., AI.S-->(A+deltaA)I.S). In the case of binary encounters, this process has been termed the Carver mechanism. The short-lived collisional change in hyperfine coupling can have very noticeable effects: it plays

J. C. Camparo

2007-01-01

305

A covariant Fokker-Planck equation for a simple gas from relativistic kinetic theory  

SciTech Connect

A manifestly covariant Fokker-Planck differential equation is derived for the case of a relativistic simple gas by taking a small momentum transfer approximation within the collision integral of the relativistic Boltzmann equation. We follow closely previous work, with the main difference that we keep manifest covariance at every stage of the analysis. In addition, we use the covariant Juettner distribution function to find a relativistic generalization of the Einstein's fluctuation-dissipation relation.

Chacon-Acosta, Guillermo; Dagdug, Leonardo; Morales-Tecotl, Hugo A. [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Mexico D. F. 09340 (Mexico)

2010-12-14

306

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

307

Theory to boil-off gas cooled shields for cryogenic storage vessels  

NASA Astrophysics Data System (ADS)

An intermediate refrigeration with boil-off gas cooled shields using the boil-off gas stream is an alternative method to the conventional intermediate refrigeration with a cryogenic liquid. By using an analytical calculation method relations are derived, which enable complete predictions about the effectiveness of an intermediate refrigeration with boil-off gas cooled shields as a function of the number of shields for the different stored cryogenic liquids. For this theoretical derivation however, the restrictive assumption must be made that the thermal conductivity of the used insulation material has a constant value between the considered temperature boundaries. For purposes of a more exact calculation a numerical method is therefore suggested, which takes into consideration that the thermal conductivity is temperature-dependent. For a liquid hydrogen storage vessel with a perlite-vacuum insulation e.g., the effectiveness of one shield and its equilibrium temperature are given as a function of the position of the shield in the insulation space.

Hofmann, A.

2004-03-01

308

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

309

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

310

Development of an implantable centrifugal blood pump.  

PubMed

The efficacy of centrifugal pumps for short-term (0-30 days) ventricular support has been widely reported and favorably compared with pulsatile systems. A small, durable, implantable centrifugal blood pump is being developed for medium-term use (up to 6 months). The pump is based on the Medtronic Hemadyne system that has existed in multiple forms over the past 30 years. The pump is approximately the size of a tennis ball, weighs 240 g, and is comprised of a 2.5 cm plastic impeller driven by a radially coupled brushless DC motor. In vitro hydraulic performance was recorded over a wide range of flow conditions on a mock circulatory loop. The pump generated 7 L/min flow against an afterload of 100 mmHg pressure, with a maximum power draw of 10.4 watts. Pulsatile flow was preserved when placed in conjunction with a simulated left ventricle. In vivo testing was performed in 10 healthy sheep for 10-292 hr. Heparin was used to facilitate cannulation, and no anticoagulation was administered after pump implantation. Blood chemistries reflecting hematologic, pulmonary, renal, and hepatic functions were recorded and demonstrated no adverse effects with normal pump operation. Complications were related to kinking of blood conduits and thrombus formation within the cannulae. These results are encouraging and warrant further studies to prove feasibility of this pump as a medium-term implantable ventricular assist device. PMID:1457882

Goldstein, A H; Pacella, J J; Trumble, D R; Clark, R E

311

Centrifugal extension of coronary intimal necrotic areas.  

PubMed

The use of serial cross-sections, camera lucida drawings and photographic reconstruction of longitudinally cut samples, revealed that about half of intimal necrotic areas present in the coronary arteries of subjects aged 41-50 years exhibited a longitudinal diameter greater than 1.0 cm, occurring as very long lesions. In the 16 intimal necrotic areas included in a tridimensional study the longitudinal diameter was 7.8 times greater than the transverse one and 11.3 times greater than the luminal-medial diameter. The important centrifugal extension of coronary intimal necrotic areas during the fifth decade of life, particularly in male subjects, could not be detected grossly; it required a meticulous light microscopic examination of stained tissue section. This centrifugal extension was sometimes associated with the presence of a "border zone" of intermediate injury developed at the point where the intimal necrotic area irradiated in the direction of blood flow. This distal side of the lesion appeared as a highly irregular boundary with numerous peninsulas of interdigitating necrotic and apparently normal connective tissue. The present results, associated with those of our previous reports, support the view that human atherosclerosis has many attributes of a necrotizing arteriopathy. PMID:3523733

Velican, C; Velican, D; Tâncu, I

312

Cytoplasmic streaming in internodal cells of Nitella under centrifugal acceleration: a study done with a newly constructed centrifuge microscope  

Microsoft Academic Search

Summary We constructed a new centrifuge microscope of the stroboscopic type, with which the cytoplasmic streaming inNitella internodal cells under centrifugal acceleration was studied. Under moderate centrifugal acceleration (ca. 50–100×g), the direction of cytoplasmic streaming in an internodal cell ofNitella is parallel to the direction of the subcortical fibrils. The speed of endoplasm flowing contiguous to the subcortical fibrils is

E. Kamitsubo; Y. Ohashi; M. Kikuyama

1989-01-01

313

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

314

Gapless Finite- T Theory of Collective Modes of a Trapped Gas  

NASA Astrophysics Data System (ADS)

We present predictions for the frequencies of collective modes of trapped Bose-condensed 87Rb atoms at finite temperature. Our treatment includes a self-consistent treatment of the effects upon the mean field from finite- T excitations and the anomalous average. This is the first gapless [A. Griffin, Phys. Rev. B 53, 9341 (1996)] calculation of this type for a trapped Bose-Einstein condensed gas. The corrections quantitatively account for the downward shift in the m = 2 excitation frequencies observed in recent experiments as the critical temperature is approached.

Hutchinson, D. A. W.; Dodd, R. J.; Burnett, K.

1998-09-01

315

Coupled-cluster theory of a gas of strongly-interacting electrons in the dilute limit  

SciTech Connect

We study the ground-state properties of a dilute gas of strongly-interacting fermions in the framework of the coupled-cluster expansion (CCE). We demonstrate that properties such as universality, opening of a gap in the excitation spectrum and applicability of s-wave approximations appear naturally in the CCE approach. In the zero-density limit, we show that the ground-state energy density depends on only one parameter which in turn may depend at most on the spatial dimensionality of the system.

Mihaila, Bodgan [Los Alamos National Laboratory; Cardenas, Andres L [Los Alamos National Laboratory

2008-01-01

316

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) cancelation of perturbation terms that appear with opposite signs in the model moment expressions. PMID:24105525

Ben-David, Avishai; Davidson, Charles E

2013-08-26

317

Screenbowl centrifuges have shown excellent results for Ruhrkohle  

SciTech Connect

In view of the fact that separating the water mechanically is less expensive and less complicated than thermal drying, RAG decided to install additional mechanical dewatering devices. Screenbowl centrifuges consist of a two-stage screw conveyor centrifuge, which combines a solid bowl with a screenbowl-type machine. The slurry is introduced through the feed pipe and subsequently goes through two stages. During the first stage, within the solid-bowl section, solids are deposited by the effects of centrifugal force. Effluent leaves the machine over the overflow weir. Pre-thickened flotation concentrate is then pushed by the screw conveyor into the second stage, the screenbowl. Centrifuged cake is further dewatered and then discharged. Effluent leaving the screenbowl is returned to the feed. The first centrifuge used on an industrial scale by Ruhrkohle was the KHD Humboldt Wedag type SVS 900 by 1800 model. This centrifuge had a rotor diameter of 900 millimeters (36 inches) and a rotor length of 1800 millimeters (72 inches). Its optimum feed rate was 10 tons per hour. The unit was run continuously for seven months without any failure or noticeable wear. Now after more than two years of continuous operation of screenbowl centrifuges in three RAG coal preparation plants, the following conclusions can be made: (1) steady and uncomplicated operation of these machines is impressive. Centrifuges are run without flocculant; they require only starting and stopping with the desired feed rate being controlled as a function of power consumption; (2) screenbowl centrifuges discharge a product of good flow properties, with good handling characteristics; (3) in cases that have a high proportion of fine particles in the feed or high throughput rates, combined operation of rotary vacuum filters with screenbowl centrifuges or the use of compartment-type presses with screenbowl centrifuges is advisable for dewatering effluent.

Bogenschneider, B.; Wilczynski, P.

1982-05-01

318

Metal/gas MHD conversion  

SciTech Connect

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.

1982-01-01

319

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

320

Local-density-functional theory for superfluid fermionic systems: The unitary gas  

NASA Astrophysics Data System (ADS)

The first detailed comparison between ab initio calculations of finite fermionic superfluid systems, performed recently by Chang and Bertsch [Phys. Rev. A 76, 021603(R) (2007)] and by von Stecher, Grange, and Blume [e-print arXiv:0705.0671v1] and the extension of the density-functional theory superfluid local-density approximation (SLDA) is presented. It is shown that SLDA reproduces the total energies, number density distributions in inhomogeneous systems along with the energy of the normal state in homogeneous systems. Unlike the Kohn-Sham LDA, in SLDA the effective fermion mass differs from the bare fermion mass and the spectrum of elementary excitations is also reproduced.

Bulgac, Aurel

2007-10-01

321

Kinetic perturbation theory. Structure of collision integrals for the square-well gas  

SciTech Connect

We seek a better understanding of the structure of kinetic perturbation theory, in inverse temperature T/sup -1/, for fluids. For a prototypic pair potential (hard core of unit diameter plus square well of width R and depth epsilon) we obtain exact results on the Boltzmann-equation level of description. We find the following: (i) for the self-diffusion collision integral ..cap omega..(/sup 1/ /sup 1/), the nonanalytic terms in w = epsilon/kT are all of the form w/sup n/ ln w and w/sup n + 1/ ln/sup 2/ w, n = 2, 3, 4, ... (ii) ..cap omega..(/sup 1/ /sup 1/) also has an essential singularity in R at R = 1; (iii) first-order perturbation theory in w is unreasonably accurate. It yields a good approximation for ..cap omega..(/sup 1/ /sup 1/) (and hence for the coefficient of self-diffusion) over a considerable region of parameter space (R/sup -1/,w), including domains over which individual higher order terms in w are larger than the first-order terms; (iv) partial sums through O(w/sup 3/ ln w) yield approximations of decreasing accuracy as more terms are included; (v) a result similar to iii is found for the thermal conductivity and its collision integral, though over a more limited region of parameter space; and (vi) the linear term in w and the leading nonanalytic terms are traced to different collision types. The significance of the above findings for perturbative treatments of the dense fluid is discussed. Results are presented also for the simpler cases of coreless square-well and repulsive (square) mound pair potentials. 9 figures.

Karkheck, J. (GMI Engineering and Management Inst., Flint, MI); Stell, G.

1983-07-21

322

Theory of charge transport in two-dimensional electron gas/noncentrosymmetric superconductor junction  

NASA Astrophysics Data System (ADS)

Based on the extended Blonder-Tinkham-Klapwijk (BTK) approach, we have investigated the charge transport in two-dimensional electron gas/noncentrosymmetric superconductor (2DEG/NCS) junction. The effects of the Rashba spin-orbit coupling (RSOC) and the interface barrier on the conductance are taken into account. It is found that there is a peak of the conductance with the Rashba strength ? in 2DEG for the nonzero Rashba strength ? in NCS. The peak feature of the conductance can be tuned largely by the interface barrier. These phenomena are essentially different from those found in FM/NCS tunneling junctions where the zero bias conductance is suppressed by ?, independent of the barrier strength.

Bai, Chunxu; Wang, Juntao; Jia, Shuanwen; Yang, Yanling

2010-07-01

323

Some theories of dissolved gas release from Tank 241-SY-101  

SciTech Connect

This report explains the ammonia release data to an order of magnitude agreement by the combination of three mechanisms of release: (1) bubble transport, (2) permeation/diffusion through the upper layers of the waste, and (3) diffusion/evaporation from freshly exposed liquid surfaces. Bounded by these mechanisms, there is low danger of extremely high ammonia concentrations in the off gas. This condition would occur through some (unlikely) continuous replenishing of fresh liquid on the surface. This would not occur unless there were continuous energetic rollovers, which seem very unlikely given historical evidence, or by energetic mixing of the waste with more power than provided by the current mixing pump. Nitrous oxide is of low solubility in the waste and behaves similarly to hydrogen.

Allemann, R.T.

1994-09-01

324

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

325

Spectroscopy in finite density lattice field theory: An exploratory study in the relativistic Bose gas  

NASA Astrophysics Data System (ADS)

We analyze 2-point functions in the relativistic Bose gas on the lattice, i.e., a charged scalar ?4 field with chemical potential ?. Using a generalized worm algorithm we perform a Monte Carlo simulation in a dual representation in terms of fluxes where the complex action problem is overcome. We explore various aspects of lattice spectroscopy at finite density and zero temperature, such as the asymmetry of forward and backward propagation in time and the transition into the condensed phase. It is shown that after a suitable subtraction the exponents for forward and backward propagation are independent of ? and agree with the mass obtained from the propagator at ?=0. This holds for ?

Gattringer, Christof; Kloiber, Thomas

2013-03-01

326

Gas-phase nucleophilic reactions in SO 2F 2: experiment and theory  

NASA Astrophysics Data System (ADS)

The gas-phase ion-molecule reactions of simple anions (HO -, CH 3O -, NH 2-) with SO 2F 2 proceed with rate constants close to the collision limit. The energy surface for the OH -/SO 2F 2 reaction has been characterized by ab initio calculations using basis functions adapted for a pseudopotential and corrected for anionic systems by the generator coordinate method (GCM) at the QCISD(T)/(ECP/TZV/GCM) level. The calculations indicate that reaction occurs by initial addition of the anion to SO 2F 2 to form a hypervalent sulfur species. The high efficiency of the reaction is associated with a low energy barrier separating the initial adduct from the product side ion-neutral complex.

Morgon, Nelson H.; Linnert, Harrald V.; de Souza, Luiz A. G.; Riveros, JoséM.

1997-09-01

327

STUDY OF ALTERNATIVE CONTROL MEASURES FOR SMALL CENTRIFUGE ENRICHMENT FACILITIES  

Microsoft Academic Search

The safeguards objectives for enrichment facilities are the detection of the diversion of declared nuclear material and of facility misuse. The safeguard approach currently applied for commercial centrifuge enrichment facilities are based on the Hexapartite Project. However in the case of small centrifuge plants, limited inventories and restricted visual access to the cascades, the misuse scenarios seems to overcome the

Marco A. Marzo; Hugo E. Vicens; Orpet M. Peixoto; Horacio Lee Gonzales

328

Numerical Analysis of Separative Power of Isotope Centrifuges, (II)  

Microsoft Academic Search

It is found from numerical analysis that a strong influence is exerted on the separative efficiency of centrifuges by the thermal convection arising from the temperature difference prevailing between the end plates of a centrifuge drum—known as “Ekman suction”. The numerical method previously developed by Nakayama & Torii is used to compute the distributions of concentration resulting from considerations of

Takuji TORII

1977-01-01

329

Development and characterization of a continuous centrifugal bioreactor  

Microsoft Academic Search

A new continuous centrifugal bioreactor (CCBR), has been developed and characterized. A densely packed fluidized bed was maintained by balancing the drag and buoyancy forces of the incoming substrate with that of the centrifugal forces. With this approach, effluent streams were relatively free of cells and a small residence time assured the provision of adequate nutrient requirements and rapid removal

B. J. Van Wie; M. L. Elliott; J. M. Lee; C. D. Scott

1986-01-01

330

The centrifugal contactor as a concentrator in solvent extraction processes  

SciTech Connect

The possibility was explored of using solvent extraction in centrifugal contactors to concentrate metal ions from a waste stream when their distribution ratio values are favorable. The theoretical basis for such a concentrator was developed and is presented here, along with experimental results which show that a centrifugal contactor is capable of acting as such a concentrator.

Leonard, R.A.; Wygmans, D.G.; McElwee, M.J.; Wasserman, M.O.; Vandegrift, G.F. [Argonne National Lab., IL (United States)

1993-01-01

331

Model of a Centrifugal Pump Coupled to a Windrotor,  

National Technical Information Service (NTIS)

A mathematical model to describe the behavior of centrifugal pumps is derived. The choice of the type of rotodynamic pump that has to be coupled to a windrotor is motivated. Next, some assumptions about the centrifugal pumps are made and the characteristi...

A. J. Staassen

1988-01-01

332

Analysis of the reliability of submersible centrifugal electric pumping systems  

Microsoft Academic Search

A modern submersible centrifugal electric pumping system (SCEPS) for oil production consists of a submersible part which includes a centrifugal pump, an electric motor, a hydroprotection arrangement, a cable line, and an aboveground part that includes a control station and a transformer. The author discusses the mean service life of the submersible part of the SCEPS as the most important

V. A. Shilyaev; G. G. Solodovnikov; R. G. Vikhman; V. A. Koshelev; G. S. Zhitina; N. I. Chirkova

1987-01-01

333

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

334

Centrifuge Modeling of Cadmium Migration in Saturated and Unsaturated Soils  

Microsoft Academic Search

Researchers recently have come to recognize that geotechnical centrifuge can provide a powerful experimental tool for investigating the flow and transport of inorganic contaminants in soils. Inert, non-adsorptive inorganic compounds (e.g., sodium ions) rather than adsorptive heavy metals are often used as the chemical for the investigation of pollutant transport behavior in most centrifuge modeling. To overcome the shortcomings of

Irene M. C. Lo; Jianhong Zhang; Liming Hu

2005-01-01

335

Protect centrifugal pumps from low flows  

SciTech Connect

Operation of centrifugal pumps below their minimum flow requirements is the primary cause of premature pump failure. Hydraulic instability occurs at low flows, causing cavitation, surging, and excessive vibration in the pump. This instability is more restrictive in setting the minimum allowable flow than using the temperature rise, which was used in the past. If you are the system design engineer, you should consider providing a protective system during the preparation of the piping and instrumentation diagrams (P and IDs). Not all pumps require a protective system. Your problem is to determine which pumps do and which do not, and decide the type of system to employ. This decision must be made as early as possible in the development of the P and IDs to avoid costly rework. This article gives guidelines on when to provide a protective system and offers examples of appropriate designs.

Woodside, O.

1995-06-01

336

Recent advances in centrifugal contactors design  

SciTech Connect

Advances in thedesign of the Argonne centrifugal contactor for solvent extaction are being realized as these contactors are built, tested, and used to implement the TRUEX process for the cleanup of nuclear waste liquids. These advances include (1) using off-the-shelf, face-mounted motors, (2) modifying the contractor so that relatively volatile solvents can be used, (3) adding a high-level liquid detector that can be used to alert the plant operator of process upsets, (4) providing secondary feed ports, (5) optimizing support frame design, (6) maintaining a linear design with external interstage lines so the stages can be allocated as needed for extraction, scrub, strip, and solvent cleanup operations, and (7) developing features that facilitate contractor operation in remote facilities. 11 refs., 8 figs.

Leonard, R.A.

1987-10-01

337

Recent advances in centrifugal contactor design  

SciTech Connect

Advances are being made in the design of the Argonne centrifugal contactor for solvent extraction. These contactors are being built, tested, and used to implement the TRUEX process for the cleanup of nuclear waste liquids. These advances include 1) using off-the-shelf, face-mounted motors; 2) modifying the contactor so that relatively volatile solvents can be used; 3) adding a high-level liquid detector that can be used to alert the plant operator of process upsets; 4 ) providing secondary feed ports; 5) optimizing support frame design; 6) devising a linear design with external interstage lines so that stages can be allocated as needed for extraction, scrub, strip, and solvent cleanup operations; and 7) developing features that facilitate contactor operation in remote facilities.

Leonard, R.A.

1988-01-01

338

Development of Centrifugal Contactor with High Reliability  

SciTech Connect

In Japan Atomic Energy Agency (JAEA), an innovative centrifugal contactor system has been developed for a future reprocessing plant. It was confirmed that it had a higher extraction capacity through the uranium test already. But it was necessary that it had the higher mechanical reliability to be applied in a reprocessing plant. In this study, two types of driving units that use a ball bearing or a magnetic bearing have been developed for it. It was confirmed that they had enough abilities trough endurance tests. The driving unit with ball bearing could be operated continuously for 5000 hours that was equal to a term of an annual operation. It was found that it could be operated for a year without maintenance. JAEA will continue to improve them and select more advantageous one on the basis of economy and lifetime in near future. (authors)

Okamura, Nobuo; Takeuchi, Masayuki; Ogino, Hideki; Kase, Takeshi; Koizumi, Tsutomu [Japan Atomic Energy Agency, Tokai-mura, Ibaraki-ken, 319-1194 (Japan)

2007-07-01

339

Recent advances in centrifugal contactor design  

SciTech Connect

Advances are being made in the design of the Argonne centrifugal contactor for solvent extraction. These contactors are being built, tested, and used to implement the TRUEX process for the cleanup of nuclear waste liquids. These advances include (1) using off-the-shelf, face-mounted motors; (2) modifying the contactor so that relatively volatile solvents can be used; (3) adding a high-level liquid detector that can be used to alert the plant operator of process upsets; (4) providing secondary feed ports; (5) optimizing support frame design; (6) devising a linear design with external interstage lines so that stages can be allocated as needed for extraction, scrub, strip, and solvent cleanup operations; and (7) developing features that facilitate contactor operation in remote facilities.

Leonard, R.A.

1988-10-01

340

Numerical simulation of centrifugal casting of pipes  

NASA Astrophysics Data System (ADS)

A numerical simulation model for the horizontal centrifugal pipe casting process was developed with the commercial simulation package Flow3D. It considers - additionally to mass, energy and momentum conservation equations and free surface tracking - the fast radial and slower horizontal movement of the mold. The iron inflow is not steady state but time dependent. Of special importance is the friction between the liquid and the mold in connection with the viscosity and turbulence of the iron. Experiments with the mold at controlled revolution speeds were carried out using a high-speed camera. From these experiments friction coefficients for the description of the interaction between mold and melt were obtained. With the simulation model, the influence of typical process parameters (e.g. melts inflow, mold movement, melt temperature, cooling media) on the wall thickness of the pipes can be studied. The comparison to results of pipes from production shows a good agreement between simulation and reality.

Kaschnitz, E.

2012-07-01

341

Quantitative centrifugation to extract benthic protozoa from freshwater sediments.  

PubMed

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, M; Bär-Gilissen, M J; Bak, R P; Cappenberg, T E

1994-01-01

342

Modeling centrifugal cell washers using computational fluid dynamics.  

PubMed

Reinfusion of shed blood during surgery could avoid the need for blood transfusions. Prior to reinfusion of the red blood cells, the shed blood must be washed in order to remove leukocytes, platelets, and other contaminants. Further, the hematocrit of the washed blood must be increased. The feasibility of using computational fluid dynamics (CFD) to guide the design of better centrifuges for processing shed blood is explored here. The velocity field within a centrifuge bowl and the rate of protein removal from the shed blood has been studied. The results obtained indicate that CFD could help screen preliminary centrifuge bowl designs, thus reducing the number of initial experimental tests required when developing new centrifuge bowls. Although the focus of this work is on washing shed blood, the methods developed here are applicable to the design of centrifuge bowls for other blood-processing applications. PMID:15504118

Kellet, Beth E; Han, Binbing; Dandy, David S; Wickramasinghe, S Ranil

2004-11-01

343

Characterization of nanoporous materials by gas adsorption and density-functional theory  

NASA Astrophysics Data System (ADS)

Nanoporous materials with pores ranging from several molecular diameters to ca. 10 nm currently find numerous applications in modern separation and catalytic technologies. Adsorption is one of the most informative experimental techniques for structural characterization of nanoporous materials. Practical problems of characterization and prediction of adsorption properties of active carbons, zeolites, pillared clays, mesoporous molecular sieves, carbon nanotubes, and many other traditional and newly synthesized adsorbents gave rise to a number of theoretical models capable of constructing adsorption isotherms in model pores. Modern methods of statistical thermodynamics such as Monte Carlo (MC) simulations, molecular dynamics (MD) and density functional theory (DFT) provide molecular level understanding of adsorption in pores, and can be used for characterization of nanoporous materials and predicting their adsorption properties. The main focus of the present work is experimental and theoretical studies of adsorption in nanoporous materials. A nonlocal density functional theory (NLDFT) model has been developed for predicting adsorption/desorption isotherms in nanopores of different geometries over a wide range of pore sizes (0.3-100 nm), and for calculating pore size distributions from the experimental adsorption isotherms based on given intermolecular fluid-fluid and fluid-solid potentials. The NLDFT model has been applied to studies of N2 and Ar adsorption and hysteresis phenomena in mesoporous molecular sieves of MCM-41-type, N 2 and CO2 adsorption on activated carbons. An important issue of comparison of the theoretical and experimental excess adsorption isotherms have been studied in details. A method of ``virtual helium calibration'' has been introduced, which makes the theoretical and experimental isotherms entirely consistent. The method is applicable to any molecular model of adsorption. Several new methods for calculating pore size distributions from experimental adsorption isotherms have been developed. Using regularization techniques NLDFT- based methods make possible the calculation of pore size distributions of (1)mesoporous molecular sieves of M41S type from low temperature N2 and Ar isotherms, (2)microporous carbons from low temperature N2, Ar isotherms, and from CO2 isotherms at ambient temperature. Theoretical results have been validated by extensive comparisons with the experimental data, and results of Monte Carlo simulations. Pore size distributions of mesoporous molecular sieves calculated from the NLDFT method are consistent with other independent methods for characterization of pore structure, such as X-ray diffraction and Transmission Electron Microscopy. The NLDFT method is a rigorous approach which is recommended for characterization of nanoporous materials.

Ravikovitch, Peter I.

344

Reciprocating flow-based centrifugal microfluidics mixer  

NASA Astrophysics Data System (ADS)

Proper mixing of reagents is of paramount importance for an efficient chemical reaction. While on a large scale there are many good solutions for quantitative mixing of reagents, as of today, efficient and inexpensive fluid mixing in the nanoliter and microliter volume range is still a challenge. Complete, i.e., quantitative mixing is of special importance in any small-scale analytical application because the scarcity of analytes and the low volume of the reagents demand efficient utilization of all available reaction components. In this paper we demonstrate the design and fabrication of a novel centrifugal force-based unit for fast mixing of fluids in the nanoliter to microliter volume range. The device consists of a number of chambers (including two loading chambers, one pressure chamber, and one mixing chamber) that are connected through a network of microchannels, and is made by bonding a slab of polydimethylsiloxane (PDMS) to a glass slide. The PDMS slab was cast using a SU-8 master mold fabricated by a two-level photolithography process. This microfluidic mixer exploits centrifugal force and pneumatic pressure to reciprocate the flow of fluid samples in order to minimize the amount of sample and the time of mixing. The process of mixing was monitored by utilizing the planar laser induced fluorescence (PLIF) technique. A time series of high resolution images of the mixing chamber were analyzed for the spatial distribution of light intensities as the two fluids (suspension of red fluorescent particles and water) mixed. Histograms of the fluorescent emissions within the mixing chamber during different stages of the mixing process were created to quantify the level of mixing of the mixing fluids. The results suggest that quantitative mixing was achieved in less than 3 min. This device can be employed as a stand alone mixing unit or may be integrated into a disk-based microfluidic system where, in addition to mixing, several other sample preparation steps may be included.

Noroozi, Zahra; Kido, Horacio; Micic, Miodrag; Pan, Hansheng; Bartolome, Christian; Princevac, Marko; Zoval, Jim; Madou, Marc

2009-07-01

345

A Battery-Type Centrifugal Dust Trap  

Microsoft Academic Search

However, battery cyclones are not very reliable. The most frequent causes of failure to work normally are encrustation of the devices in the individual cyclone elements, which is accompanied by escape of the dirty gas from the bunker into the clean-gas chamber, and also can be due to the gas bypassing the cyclone elements because of wear in the exit

A. Yu. Val'dberg; F. E. Dubinskaya; Yu. V. Kovalevskii; V. K. Burkov; V. A. Lifanov

2003-01-01

346

Modified Coulomb gas construction of quantum Hall states from nonunitary conformal field theories  

SciTech Connect

Some fractional quantum Hall states observed in experiments may be described by first-quantized wavefunctions with special clustering properties such as the Moore-Read Pfaffian for filling factor {nu}=5/2. This wavefunction has been constructed by constructing correlation functions of a two-dimensional conformal field theory (CFT) involving a free boson and a Majorana fermion. By considering other CFTs many other clustered states have been proposed as candidate fractional quantum Hall states under appropriate circumstances. It is believed that the underlying CFT should be unitary if one wants to describe an incompressible, i.e., gapped liquid state. We show that by changing the way one derives the wavefunction from its parent CFT it is possible to obtain an incompressible candidate state when starting from a nonunitary parent. The construction mimics a global change in parameters in the phase space of the electron system. We explicit our construction in the case of the so-called Gaffnian state (a state for filling factor 2/5) and also for the Haldane-Rezayi state (a spin-singlet state at filling 1/2). We note that there are obstructions along this path in the case of the permanent spin-singlet state of Read and Rezayi which can be characterized as a robust gapless state.

Milovanovic, M. V.; Vidanovic, I. [Institute of Physics, P.O. Box 68, 11080 Belgrade (Serbia); Jolicoeur, Th. [Laboratoire de Physique Theorique et Modeles Statistiques, Universite Paris-Sud, 91405 Orsay (France)

2009-10-15

347

A straight path centrifugal blood pump concept in the Capiox centrifugal pump.  

PubMed

This article describes comparative studies of a newly developed "straight path" centrifugal pump (Capiox centrifugal pump) targeted for open-heart surgery and circulatory support. A unique straight path design of the rotor was very effective in reducing the pump's rotational speed and prime volume. This pump was evaluated for hydraulics, hemolysis, depriming characteristics, cavitation, and heat generation. Two commercially available centrifugal pumps, the Biomedicus cone-type pump and the Sarns 3M impeller-type pump, were used as controls. The new pump required the lowest pump speed to produce the same flow rates under the same pressure loads and demonstrated the lowest hemolysis and the lowest temperature rise with the outlet clamped. The air volume required to deprime the new pump was one-third to one-half that for the other pumps, and no sign of cavitation was observed even if a small amount of air was introduced to the pump inlet under a negative pressure of 200 mm Hg. PMID:8338432

Kijima, T; Oshiyama, H; Horiuchi, K; Nogawa, A; Hamasaki, H; Amano, N; Nojiri, C; Fukasawa, H; Akutsu, T

1993-07-01

348

Theory and practice of a variable dome splitter for gas chromatography-olfactometry.  

PubMed

For olfactometric measurements in combination with gas chromatography a device is needed to split the GC effluent between the detector and the sniffing port. Fixed split ratios are obtained by simple flow splitters with appropriate restrictions towards the two outlets. Variable split ratios are possible with additional control flows. One such device is a dome splitter with one input flow (the GC effluent), two output flows (to the two outlets) and two control inputs. Preliminary experiments revealed deviations from the expected split ratios of such a device. The dimensioning of the flow restrictors at only one working point was not sufficient to obtain the expected split ratios over the whole temperature range of a GC run. Therefore a physical model of the flow system has been developed, taking into account the temperature dependence of the restrictors and the internal pressure in the dome. This included the solution of the flow (respectively the mass) balance under the condition of a compressible, isothermal and laminar flow regime. The measurements are in good agreement with theoretical calculations. The model can therefore be used to optimise the dimensions of the restrictions and to calculate the effective split ratio at a given temperature during the GC run. PMID:23489489

Boeker, Peter; Haas, Torsten; Schulze Lammers, Peter

2013-02-26

349

Separation Control in a Centrifugal Bend Using Plasma Actuators  

NASA Astrophysics Data System (ADS)

An experiment and CFD simulation are presented to examine the use of plasma actuators to control flow separation in a 2-D channel with a 135^o inside-bend that is intended to represent a centrifugal bend in a gas turbine engine. The design inlet conditions are P=330,sia., T=1100^oF, and M=0.24. For these conditions, the flow separates on the inside radius of the bend. A CFD simulation was used to determine the location of the flow separation, and the conditions (location and voltage) of a plasma actuator that was needed to keep the flow attached. The plasma actuator body force model used in the simulation was updated to include the effect of high-pressure operation. An experiment was used to validate the simulation and to further investigate the effect of inlet pressure and Mach number on the flow separation control. This involved a transient high-pressure blow-down facility. The flow field is documented using an array of static pressure taps in the channel outside-radius side wall, and a rake of total pressure probes at the exit of the bend. The results as well as the pressure effect on the plasma actuators are presented.

Arthur, Michael; Corke, Thomas

2011-11-01

350

Developments in centrifugal compressor surge control: A technology assessment  

NASA Astrophysics Data System (ADS)

There are a number of surge control schemes in current use for centrifugal compressors employed in natural gas transmission systems. Basically, these schemes consist of a set of detection devices that either anticipate surge or detect it at its inception, and a set of control devices that act to prevent surge from occurring. A patent search was conducted in an attempt to assess the level and direction of technology development over the last 20 years and to define the focus for future R&D activities. In addition, the paper presents the current state of technology in three areas: surge control, surge detection, and surge suppression. Patent data obtained from on-line databases showed that most of the emphasis has been on surge control rather than on detection and control and that the current trend in surge control will likely continue toward incremental improvement of a basic or conventional surge control strategy. Various surge suppression techniques can be grouped in two categories: (i) those that are focused on better compressor interior design, and (ii) others that attempt to suppress surge by external and operational means.

Botros, K. K.; Henderson, J. F.

1994-04-01

351

Developments in a centrifugal compressor surge control -- a technology assessment  

SciTech Connect

There are a number of surge control schemes in current use for centrifugal compressors employed in natural gas transmission systems. Basically, these schemes consist of a set of detection devices that either anticipate surge or detect it at its inception, and a set of control devices that act to prevent surge from occurring. A patent search was conducted in an attempt to assess the level and direction of technology development over the last 20 years and to define the focus for future R D activities. In addition, the paper presents the current state of technology in three areas: surge control, surge detection, and surge suppression. Patent data obtained from on-line databases showed that most of the emphasis has been on surge control rather than on detection and control and that the current trend in surge control will likely continue toward incremental improvement of a basic or conventional surge control strategy. Various surge suppression techniques can be grouped in two categories: (1) those that are focused on better compressor interior design, and (2) others that attempt to suppress surge by external and operational means.

Botros, K.K.; Henderson, J.F. (NOVACOR Research Technology Corp., Calgary, Alberta (Canada))

1994-04-01

352

Theory of femtosecond coherent anti-Stokes Raman scattering spectroscopy of gas-phase transitions.  

PubMed

A theoretical analysis of coherent anti-Stokes Raman scattering (CARS) spectroscopy of gas-phase resonances using femtosecond lasers is performed. The time-dependent density matrix equations for the femtosecond CARS process are formulated and manipulated into a form suitable for solution by direct numerical integration (DNI). The temporal shapes of the pump, Stokes, and probe laser pulses are specified as an input to the DNI calculations. It is assumed that the laser pulse shapes are 70 fs Gaussians and that the pulses are Fourier-transform limited. A single excited electronic level is defined as an effective intermediate level in the Raman process, and transition strengths are adjusted to match the experimental Raman polarizability. The excitation of the Raman coherence is investigated for different Q-branch rotational transitions in the fundamental 2330 cm(-1) band of diatomic nitrogen, assuming that the pump and Stokes pulses are temporally overlapped. The excitation process is shown to be virtually identical for transitions ranging from Q2 to Q20. The excitation of the Raman coherences is also very efficient; for laser irradiances of 5x10(17) W/m2, corresponding approximately to a 100 microJ, 70 fs pulse focused to 50 microm, approximately 10% of the population of the ground Raman level is pumped to the excited Raman level during the impulsive pump-Stokes excitation, and the magnitude of the induced Raman coherence reaches 40% of its maximum possible value. The theoretical results are compared with the results of experiments where the femtosecond CARS signal is recorded as a function of probe delay with respect to the impulsive pump-Stokes excitation. PMID:17672699

Lucht, Robert P; Kinnius, Paul J; Roy, Sukesh; Gord, James R

2007-07-28

353

Centrifugal compressor modifications and their effect on high-frequency pipe wall vibration  

SciTech Connect

High-frequency pulsation generated by centrifugal compressors, with pressure wave-lengths much smaller than the attached pipe diameter, can cause fatigue failures of the compressor internals, impair compressor performance, and damage the attached compressor piping. There are numerous sources producing pulsation in centrifugal compressors. Some of them are discussed in literature at large (Japikse, 1995; Niese, 1976). NGTL has experienced extreme high-frequency discharge pulsation and pipe wall vibration on many of its radial inlet high-flow centrifugal gas compressor facilities. These pulsations led to several piping attachment failures and compressor internal component failures while the compressor operated within the design envelope. This paper considers several pulsation conditions at an NGTL compression facility which resulted in unacceptable piping vibration. Significant vibration attenuation was achieved by modifying the compressor (pulsation source) through removal of the diffuser vanes and partial removal of the inlet guide vanes (IGV). Direct comparison of the changes in vibration, pulsation, and performance are made for each of the modifications. The vibration problem, probable causes, options available to address the problem, and the results of implementation are reviewed. The effects of diffuser vane removal on discharge pipe wall vibration as well as changes in compressor performance are described.

Motriuk, R.W.; Harvey, D.P. [Nova Gas Transmission Ltd., Calgary, Alberta (Canada)

1998-08-01

354

Characterization of instability initiation in centrifugal compressors  

NASA Astrophysics Data System (ADS)

On a compressor performance map, the region of unstable operation is bounded by the surge line. As operation in this unstable region can be detrimental to the integrity of the machine, a surge margin is maintained. The proximity of the surge line to the compressor maximum pressure rise makes a reduction in the required surge margin desirable. Prior to establishing a strategy for designing a compressor with reduced surge margin, an understanding of the instability initiation process must be attained. The determination of the role that rotating stall plays in surge initiation of high speed compressors is of particular interest. Toward this end, a series of experiments at both low and high speed were undertaken to characterize centrifugal compressor rotating stall. Utilizing spatial arrays of inlet microphones and impeller mounted microphones, the origin of the low speed compressor rotating stall is found to be a separation zone near the impeller midchord that propagates at the stall frequency. This disturbance grows as the compressor is destabilized. The impeller flowfield during rotating stall has also been measured using PIV. The inducer region shows no separation at midspan. A region of zero relative velocity is located during the stall cycle at 70% impeller meridional chord. The investigation of the high-speed centrifugal compressor has identified two distinct rotating stall modes, a one mode and a nine mode. Both are located at or near the diffuser. Examination of the component performance reveals that the one mode is associated with mild or deep surge cycles while the nine mode exists independently and serves as a blockage, reducing diffuser performance. Rotating stall is observed between surge cycles, similar to axial compressor results. A surge chamber diffuser is employed and produces a 1% increase in maximum stable pressure coefficient. The surge chamber reduces the magnitude of the rotating stall by 60%. Speed transients at constant throttle settings are examined and reveal three distinct instabilities, deep surge, mild surge and stable rotating stall. The compressor exhibits rotating stall at surge initiation and termination.

Oakes, William Charles

355

Numerical simulation for a centrifugal heart pump  

NASA Astrophysics Data System (ADS)

The primary focus of this work is to investigate unsteady flow simulations for an incompressible fluid. Computational codes are developed and applied for the purpose of analyzing the flow in a centrifugal heart pump, the Innovative Ventricular Assist System (IVAS) pump, which was developed by the Cleveland Clinic Foundation as a part of the National Institute of Health's artificial heart program. In order to simulate the complex flow in the IVAS pump, three capabilities must be incorporated into the simulation codes. The first capability is that the code must be able to simulate the flow through an IVAS pump for Reynolds numbers 30,000~80,000 with numerical stability. The Reynolds numbers in this range are considered to be high in incompressible flow and to have difficulty in simulating a flow with numerical stability. The second capability is that the codes must solve 2-1/2 dimensional Navier-Stokes equations. The 2-1/2 dimensional Navier- Stokes equations are written in such a way that the effect of the variable thickness is included in two- dimensions. The 2-1/2 dimensional analysis enables the simulation of the flow, including the various thickness effects, at nearly the computational speed of two- dimensional analysis. The third capability is that the code must simulate the flow for the entire centrifugal pump, which includes an inlet, rotating blades, a volute, and a diffuser. To perform this intensive calculation, parallel computing is used because of its high computing speed and its ability to accommodate the large computational domain by task partitioning. An intensive parametric study using a single-processor computer is performed with a view to identifying certain problematic aspects of the design methodology. According to the present analysis, the effects of a Reynolds number based on the blade radius and its velocity are not significant for typical pump operation conditions. The flow characteristics, however, change with the Reynolds numbers when they are low. In general, the pressure rise across the pump impeller increases as the radius of the blade arc increases and as the number of blades increases. The findings of this study qualitatively agree with the Euler turbine equation with respect to the effects of the leading edge (inflow) angle and the trailing edge (outflow) angle.

Yano, Keiji

356

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

357

Centrifugal pumps: which suction specific speeds are acceptable  

SciTech Connect

Suction specific speed is an important consideration when purchasing or analyzing centrifugal pumps. There is a direct correlation between this parameter, pump reliability and maintenance expenses. This article demonstrates that in a large Gulf Coast oil refinery, centrifugal pumps with a suction specific speed greater than 11,000 failed at a frequency nearly twice that of centrifugal pumps with suction specific speed less than 11,000. This study consisted primarily of hydrocarbon pumps with an average horsepower of 150 hp. Results may vary some from those found if high energy water pumps are studied. 5 refs.

Hallam, J.L.

1982-04-01

358

Efficiency calculation and the vortex characteristics research of centrifugal pump  

NASA Astrophysics Data System (ADS)

Efficiency is an important performance indicator of the centrifugal pump, this paper establish three-dimensional model of one high head centrifugal pump in domestic with CFD software, though changing the operating conditions, statistics the calculation efficiency and energy loss under different operating conditions, compare the impact to efficiency and head calculation with steady and unsteady calculation methods, and research the affect when runner in different locations in the centrifugal pump, given and analysis the reasons of the flow field and pressure distribution of runner in different steps.

Ge, X. F.; Gao, Z. X.; Zheng, Y.; Shen, M. H.

2012-11-01

359

A numerical theory of lattice gas and lattice Boltzmann methods in the computation of solutions to nonlinear advective-diffusive systems  

SciTech Connect

A numerical theory for the massively parallel lattice gas and lattice Boltzmann methods for computing solutions to nonlinear advective-diffusive systems is introduced. The convergence theory is based on consistency and stability arguments that are supported by the discrete Chapman-Enskog expansion (for consistency) and conditions of monotonicity (in establishing stability). The theory is applied to four lattice methods: Two of the methods are for some two-dimensional nonlinear diffusion equations. One of the methods is for the one-dimensional lattice method for the one-dimensional viscous Burgers equation. And one of the methods is for a two-dimensional nonlinear advection-diffusion equation. Convergence is formally proven in the L{sub 1}-norm for the first three methods, revealing that they are second-order, conservative, conditionally monotone finite difference methods. Computational results which support the theory for lattice methods are presented. In addition, a domain decomposition strategy using mesh refinement techniques is presented for lattice gas and lattice Boltzmann methods. The strategy allows concentration of computational resources on regions of high activity. Computational evidence is reported for the strategy applied to the lattice gas method for the one-dimensional viscous Burgers equation. 72 refs., 19 figs., 28 tabs.

Elton, A.B.H.

1990-09-24

360

Ligand field photofragmentation spectroscopy of [Ag(L)N]2+ complexes in the gas phase: experiment and theory.  

PubMed

Experiments have been undertaken to record photofragmentation spectra from a series of [Ag(L)N]2+ complexes in the gas phase. Spectra have been obtained for silver(II) complexed with the ligands (L): acetone, 2-pentanone, methyl-vinyl ketone, pyridine, and 4-methyl pyridine (4-picoline) with N in the range of 4-7. A second series of experiments using 1,1,1,3-fluoroacetone, acetonitrile, and CO2 as ligands failed to show any evidence of photofragmentation. Interpretation of the experimental data has come from time-dependent density functional theory (TDDFT), which very successfully accounts for trends in the spectra in terms of subtle differences in the properties of the ligands. Taking a sample of three ligands, acetone, pyridine, and acetonitrile, the calculations show all the spectral transitions to involve ligand-to-metal charge transfer, and that wavelength differences (or lack of spectra) arise from small changes in the energies of the molecular orbitals concerned. The calculations account for an absence in the spectra of any effects due to Jahn-Teller distortion, and they also reveal structural differences between complexes where the coordinating atom is either oxygen or nitrogen that have implications for the stability of silver(II) compounds. Where possible, comparisons have also been made with the physical properties of condensed phase silver(II) complexes. PMID:17705600

Guan, Jingang; Puskar, Ljiljana; Esplugas, Ricardo O; Cox, Hazel; Stace, Anthony J

2007-08-14

361

Ligand field photofragmentation spectroscopy of [Ag(L)N]2+ complexes in the gas phase: Experiment and theory  

NASA Astrophysics Data System (ADS)

Experiments have been undertaken to record photofragmentation spectra from a series of [Ag(L)N]2+ complexes in the gas phase. Spectra have been obtained for silver(II) complexed with the ligands (L): acetone, 2-pentanone, methyl-vinyl ketone, pyridine, and 4-methyl pyridine (4-picoline) with N in the range of 4-7. A second series of experiments using 1,1,1,3-fluoroacetone, acetonitrile, and CO2 as ligands failed to show any evidence of photofragmentation. Interpretation of the experimental data has come from time-dependent density functional theory (TDDFT), which very successfully accounts for trends in the spectra in terms of subtle differences in the properties of the ligands. Taking a sample of three ligands, acetone, pyridine, and acetonitrile, the calculations show all the spectral transitions to involve ligand-to-metal charge transfer, and that wavelength differences (or lack of spectra) arise from small changes in the energies of the molecular orbitals concerned. The calculations account for an absence in the spectra of any effects due to Jahn-Teller distortion, and they also reveal structural differences between complexes where the coordinating atom is either oxygen or nitrogen that have implications for the stability of silver(II) compounds. Where possible, comparisons have also been made with the physical properties of condensed phase silver(II) complexes.

Guan, Jingang; Puškar, Ljiljana; Esplugas, Ricardo O.; Cox, Hazel; Stace, Anthony J.

2007-08-01

362

Recovery of materials from waste printed circuit boards by vacuum pyrolysis and vacuum centrifugal separation.  

PubMed

In this research, a two-step process consisting of vacuum pyrolysis and vacuum centrifugal separation was employed to treat waste printed circuit boards (WPCBs). Firstly, WPCBs were pyrolysed under vacuum condition at 600 °C for 30 min in a lab-scale reactor. Then, the obtained pyrolysis residue was heated under vacuum until the solder was melted, and then the molten solder was separated from the pyrolysis residue by the centrifugal force. The results of vacuum pyrolysis showed that the type-A of WPCBs (the base plates of which was made from cellulose paper reinforced phenolic resin) pyrolysed to form an average of 67.97 wt.% residue, 27.73 wt.% oil, and 4.30 wt.% gas; and pyrolysis of the type-B of WPCBs (the base plates of which was made from glass fiber reinforced epoxy resin) led to an average mass balance of 72.20 wt.% residue, 21.45 wt.% oil, and 6.35 wt.% gas. The results of vacuum centrifugal separation showed that the separation of solder was complete when the pyrolysis residue was heated at 400 °C, and the rotating drum was rotated at 1200 rpm for 10 min. The pyrolysis oil and gas can be used as fuel or chemical feedstock after treatment. The pyrolysis residue after solder separation contained various metals, glass fibers and other inorganic materials, which could be recycled for further processing. The recovered solder can be reused directly and it can also be a good resource of lead and tin for refining. PMID:20655190

Zhou, Yihui; Wu, Wenbiao; Qiu, Keqiang

2010-07-22

363

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

364

Findlay implantable two-stage centrifugal pump.  

PubMed

The Findlay centrifugal pump is unique in its two-stage pumping mechanisms and in its complementary interrelationship of the stages to each other and to the exit system, and it forms an extremely efficient unit. The first stage is a lift force pump as an inlet. The second and major stage is a shear force pump. Twenty-six prototypes, many multiply modified, have been hand fabricated, and most have had classic pump function analyses. Six pumps have demonstrated minimal hemolysis (3.5-5 h). At modest rotation speeds, it pumps water up to 10 L/min. Forty-four acute studies in normal dogs have been performed with the Findlay pump in a ventricular assist system. Blood flows through the pump ranged from 1.2 to 4.5 L/min. The conclusion is that the Findlay pump has the ability to operate with low blood damage, performs at acceptable rotational speed with reasonable hydraulic and mechanical efficiency, and is small and implantable. PMID:8817947

Moulder, P V; Findlay, I S; Zone, R M; Thompson, A J; Silber, H A; Rank, W R; Charbonnet, M D; Webb, W R; Harrison, L H

1996-06-01

365

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

NASA Astrophysics Data System (ADS)

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 of parameters is performed, which reveals good agreement between the numerical and experimental results for a turbulent fluid flow between parallel disks.

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

2010-03-01

366

18. View north of Tropic Chamber Worthington centrifugal compressor and ...  

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

18. View north of Tropic Chamber Worthington centrifugal compressor and control panel, in machine area. - Natick Research & Development Laboratories, Climatic Chambers Building, U.S. Army Natick Research, Development & Engineering Center (NRDEC), Natick, Middlesex County, MA

367

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

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

25. RW Meyer Sugar Mill: 1876-1889. Centrifugals, 1879, 1881. Manufacturer, Unknown. Supplied by Honolulu Iron Works, Honolulu, Hawaii, 1879, 1881. View: After sugar was granulated and cooled it had to be dried and drained, completely separating the sugar crystals from the molasses. Revolving at 1200 rpm the inner basket drove the molasses outward into the stationary outer basket leaving dried sugar behind. The steam engine counter-shaft at the left was belt driven and belts running from the counter-shaft pulleys to the centrifugals' base-pulleys provided the necessary power. Part of the clutch system which moved the belt from a moving to a stationary pulley, thus turning the centrifugals on and off, is seen in Between the counter-shaft and the centrifugals. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

368

Packing of oxide ceramic powders by centrifugal casting  

NASA Astrophysics Data System (ADS)

Topical commercially available powders of silica, zinc oxide, tin oxide, and alumina were centrifugally cast. The purpose of the study was to determine the feasibility of centrifugal casting well-dispersed slips of such ceramic oxide powders to obtain high green densities and to observe the effects that deviations from an ideal monodisperse, spherical powder have on the resulting packing density. The powders were characterized by particle size distributions and microscopy. Viscosity versus pH data were obtained for those powders for which there was a sufficient quantity. The results generally showed a good correlation of centrifugal casting density with the degree of powder dispersion as measured by viscosity. However, the packing densities obtained were not higher than those which can be obtained by conventional slip casting or dry pressing. It can be concluded that centrifugal casting of typical ceramic powders does not offer any advantage over other consolidation processes.

Shaffer, G. W.; Readey, D. W.

1982-09-01

369

3. Interior view of centrifugal pump house showing pumps and ...  

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

3. Interior view of centrifugal pump house showing pumps and engines, looking W. - Laurel Valley Sugar Plantation, Drainage Plant, 2 Miles South of Thibodaux on State Route 308, Thibodaux, Lafourche Parish, LA

370

23. TEMPORARY CENTRIFUGAL PUMP. NOTE CHAPMAN HYDRAULICOPERATED VALVE FOR LATER ...  

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

23. TEMPORARY CENTRIFUGAL PUMP. NOTE CHAPMAN HYDRAULIC-OPERATED VALVE FOR LATER CONNECTION OF ENGINE PUMP ENG TO DISCHARGE HEADER. - Lakeview Pumping Station, Clarendon & Montrose Avenues, Chicago, Cook County, IL

371

2. View of centrifugal pump house sitting at edge of ...  

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

2. View of centrifugal pump house sitting at edge of drainage canal, looking E. - Laurel Valley Sugar Plantation, Drainage Plant, 2 Miles South of Thibodaux on State Route 308, Thibodaux, Lafourche Parish, LA

372

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

373

TECHNOLOGY EVALUATION REPORT: RETECH'S PLASMA CENTRIFUGAL FURNACE - VOLUME I  

EPA Science Inventory

A demonstration of the Retech, Inc. Plasma Centrifugal Furnace (PCF) was conducted under the Superfund Innovative Technology Evaluation (SITE) Program at the Department of Energy's (DOE's) Component Development and Integration Facility in Butte, Montana. The furnace uses heat gen...

374

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

2012-12-19

375

Study of Blade Clearance Effects on Centrifugal Pumps.  

National Technical Information Service (NTIS)

A program of analysis, design, fabrication, and testing has been conducted to develop and experimentally verify analytical models to predict the effects of impeller blade clearance on centrifugal pumps. The effect of tip clearance on pump efficiency, and ...

R. K. Hoshide C. E. Nielson

1972-01-01

376

Blood culture technique based on centrifugation: clinical evaluation.  

PubMed

A total of 1,000 blood samples from patients suspected of having a bacteremia were analyzed concurrently, where possible, by three methods: (i) Trypticase soy broth with sodium polyanethol sulfonate and a CO2 atmosphere: (ii) pour plates with either brain heart infusion agar or Sabouraud dextrose agar; and (iii) centrifugation of the suspected organism in a hypertonic solution. There were 176 positive cultures. The centrifugation technique recovered 73% of the positive cultures. The broth and pour plate techniques recovered 38 and 49%, respectively. The centrifugation technique showed an increased isolation rate for Pseudomonas, fungi, and gram-positive cocci. In general, for each organism the time required for the detection of a positive culture was shortest for the centrifugation technique. PMID:1270591

Dorn, G L; Burson, G G; Haynes, J R

1976-03-01

377

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

378

Manufacture of hollow ingots using centrifugal casting machines  

NASA Astrophysics Data System (ADS)

Centrifugal machines are proposed for the foundry created at the Almalyk Mining and Smelting Factory in order to produce hollow ingots of a liquid metal made by remelting of consumable electrodes in a refractory accumulating crucible.

Pomeshchikov, A. G.; Greneva, T. S.; Baidachenko, V. I.; Berezin, V. I.

2010-12-01

379

Effect of the centrifugal forces on the finite element eigenvalue solution of a rotating blade: a comparative study  

Microsoft Academic Search

In this study, the effect of the centrifugal forces on the eigenvalue solution obtained using two different nonlinear finite\\u000a element formulations is examined. Both formulations can correctly describe arbitrary rigid body displacements and can be used\\u000a in the large deformation analysis. The first formulation is based on the geometrically exact beam theory, which assumes that the cross section does not

Luis G. Maqueda; Olivier A. Bauchau; Ahmed A. Shabana

2008-01-01

380

Computer-aided manufacturing of centrifugal SHS coatings  

Microsoft Academic Search

A computer-aided process for coated-pipe manufacturing using a centrifugal self-propagating high-temperature synthesis (SHS) technique is proposed. The process is based on the occurrence of a thermite reaction involving Fe2O3 and aluminum in a field of centrifugal forces and it allows for the preparation of coatings constituted by a ceramic layer of alumina in the innermost region of the pipe and

Barbara Simoncini; Pier Fortunato Virdis; Giacomo Cao

1996-01-01

381

Unsteady flow in a viscous oil transporting centrifugal pump  

Microsoft Academic Search

Acoustic resonances are frequently fatal problems in centrifugal pump operations. Low pressure pulsation of fluid in the blade\\u000a pass frequency is helpful to prevent from such problems. In addition, for a high quality centrifugal pump, a lower broadband\\u000a noise level is also on demand. The acoustic resonance and broadband noise are associated with unsteadiness of flow in the\\u000a pump. Even

Wen-Guang Li

2011-01-01

382

Present state and development trends of foreign centrifuge construction  

Microsoft Academic Search

years. Sedimentation Centrifuges with Conveyor Cake Discharge : now produced by more than 25 firms in 11 countries. Until recently, most of these centrifuges were manufactured with conical rotors whichhad a length to diameter (L\\/D) ratio of 1.5-1.7. These were universal machines which were used for clarification of dilute, fine suspensions, as well as for separation of concentrated, coarse suspensions.

D. E. Shkoropad

1969-01-01

383

Process intensification: water electrolysis in a centrifugal acceleration field  

Microsoft Academic Search

Intensification of hydrogen production by carrying out water electrolysis in a centrifugal acceleration field has been demonstrated.\\u000a A prototype single cell rotary water electrolyser was constructed, and a number of design challenges with regard to the practical\\u000a application were addressed. The rotary electrolyser was tested over a range of current density, centrifugal acceleration,\\u000a electrolyte concentration, temperature, and electrode geometry. The

L. Lao; C. Ramshaw; H. Yeung

2011-01-01

384

Hemocompatibility of a hydrodynamic levitation centrifugal blood pump  

Microsoft Academic Search

A noncontact type centrifugal pump without any complicated control or sensing modules has been developed as a long-term implantable\\u000a artificial heart. Centrifugal pumps with impellers levitated by original hydrodynamic bearings were designed and have been\\u000a modified through numerical analyses and in vitro tests. The hemolysis level was reduced by changing the pressure distribution around the impeller and subsequently expanding\\u000a the

Takashi Yamane; Osamu Maruyama; Masahiro Nishida; Ryo Kosaka; Daisuke Sugiyama; Yusuke Miyamoto; Hiroshi Kawamura; Takahisa Kato; Takeshi Sano; Takeshi Okubo; Yoshiyuki Sankai; Osamu Shigeta; Tatsuo Tsutsui

2007-01-01

385

Nanofibers: Electrospinning and centrifugal spinning for cell biology studies  

Microsoft Academic Search

Summary form only given. A large amount of three-dimensional (3D) scaffolds will be needed for cell proliferation and tissue engineering applications. To meet the requirement of high throughput and low cost manufacturing, we have investigated a few of laboratory-scale fabrication methods, including i) micro contact thermal printing of electrospun nanofibers, ii) centrifugal melt spinning and iii) solvent assisted centrifugal spinning.

J. Shi; L. Wang; L. Liu; Y. Chen

2010-01-01

386

Investigation of surge behavior in a micro centrifugal compressor  

Microsoft Academic Search

This paper reports the experimental and theoretical study of the surge occurred in prototyping an ultra micro centrifugal\\u000a compressor. As the first step, the 10 times size model of an ultra micro centrifugal compressor having the 40 mm outer diameter\\u000a was designed and manufactured. The detailed experimental investigations for the transient behavior of surge with several different\\u000a values of B

Shimpei Mizuki; Yuichiro Asaga; Yushi Ono; Hoshio Tsujita

2006-01-01

387

Methods of rotating stall and surge detection in centrifugal compressors  

Microsoft Academic Search

Systems for prevention of surging of centrifugal compressors and methods of rotating stall detection and early surge diagnosis\\u000a using statistical processing of sensor signals of various parameters, i.e., the method of calculation of the correlation function\\u000a of the signal and the method of calculation of signal dispersion, are discussed. The results of routine tests of air and high-speed\\u000a air centrifugal

Ya. Z. Guzel’baev; A. L. Khavkin; I. G. Khisameev

2006-01-01

388

Experimental analysis of centrifugal dewatering process of polyelectrolyte flocculated waste activated sludge  

Microsoft Academic Search

The study experimentally investigated the centrifugal separation of moisture from activated sludge subject to cationic polyelectrolyte flocculation. An arm-suspended centrifuge was employed which allowed in-situ detection on all positions of interfaces of centrifuged sludge as functions of time. Experimental results revealed that, sludge flocculation would yield a significant sedimentation effect at the first phase of centrifugation. Therefore, not as suggested

C. P Chu; D. J Lee

2001-01-01

389

COMPARISON OF FATIGUE BEHAVIOR FOR CENTRIFUGALLY CAST AND KEEL BLOCK CAST STEEL  

Microsoft Academic Search

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 to statically cast keel block castings. Specimens were machined from centrifugal and keel block AISI 8630 steel castings. Centrifugal casting specimens were taken from three different locations (outer, middle

J. J. Gradman; R. I. Stephens; R. A. Hardin; C. Beckermann

390

Gas-phase reactions of [VO2(OH)2]- and [V2O5(OH)]- with methanol: experiment and theory.  

PubMed

The gas-phase reactivity of the vanadium hydroxides [VO(2)(OH)(2)](-) and [V(2)O(5)(OH)](-) toward methanol was examined using a combination of ion-molecule reactions (IMRs) and collision-induced dissociation (CID) in a quadrupole ion trap mass spectrometer. Isotope-labeling experiments with CD(3)OH, (13)CH(3)OH, and CH(3)(18)OH were used to confirm the stoichiometry of ions and the observed sequence of reactions. The experimental data were interpreted with the aid of density functional theory calculations, carried out at the B3LYP/SDD6-311++G** level of theory. While [VO(2)(OH)(2)](-) is unreactive, [V(2)O(5)(OH)](-) undergoes a metathesis reaction to yield [V(2)O(5)(OCH(3))](-). The DFT calculations reveal that the metathesis reaction of methanol with [VO(2)(OH)(2)](-) suffers from a barrier of +0.52 eV (relative to separated reactants) but that the reaction of [V(2)O(5)(OH)](-) with methanol readily proceeds via addition/elimination reactions with both transition states being below the energy of the separated reactants. CID of [V(2)O(5)(OCH(3))](-) (m/z 213) yields three ions arising from activation of the methoxo ligand: [V(2), O(6), C, H](-) (m/z 211); [V(2), O(5), H](-) (m/z 183); and [V(2), O(4), H](-) (m/z 167). Additional experiments and DFT calculations suggest that these ions arise from losses of H(2), formaldehyde and the sequential losses of H(2) and CO(2), respectively. The use of an (18)O-labeled methoxo ligand in [V(2)O(5)((18)OCH(3))](-) (m/z 215) showed the competing losses of H(2)C(16)O and H(2)C(18)O and [H(2) and C(16)O(18)O] and [H(2) and C(16)O(2)], highlighting that (16)O/(18)O exchange between the methoxo ligand and the vanadium oxide occurs prior to the subsequent fragmentation of the ligand. DFT calculations reveal that a key step involves hydrogen atom transfer from the methoxo ligand to the oxo ligand of the same vanadium center, producing the intermediate [V(2)O(4)(OH)(OCH(2))](-) containing a ketyl radical ligand and a hydroxo ligand. This intermediate can either undergo CH(2)O loss, or the ketyl radical can couple with an oxo ligand of the adjacent vanadium center, producing [V(2)O(3)(?(2)-O(2)CH(2))](-), which is a key intermediate in the (16)O/(18)O scrambling and in the H(2) loss channel. PMID:22889366

Harris, Benjamin L; Waters, Tom; Khairallah, George N; O'Hair, Richard A J

2012-08-13

391

Application of pressure sensitive paint measurement to a low-solidity cascade diffuser of a transonic centrifugal compressor  

Microsoft Academic Search

A pressure sensitive paint (PSP) measurement has been known as a pressure field measurement technique based on the oxygen\\u000a quenching phenomenon of luminescence of specific luminophores. A PSP measurement was applied for pressure field measurement\\u000a in a low-solidity circular cascade diffuser of a single-stage transonic centrifugal compressor with 5 in pressure ratio for\\u000a HFC134a gas. The oxygen concentration was about

H. Hayami; M. Hojo; M. Matsumoto; S. Aramaki; K. Yamada

2002-01-01

392

Variational stabilization of the ionic charge densities in the electron-gas theory of crystals: Applications to MgO and CaO  

Microsoft Academic Search

The electron-gas theory of crystals is extended to include the effects of many-body forces that arise from both electrostatic and overlap interactions. These effects are incorporated through a self-consistent spherical relaxation of the ionic charge distributions such that the crystal binding energy is minimized. This variational model is used to compute the elastic constants and equations of state of MgO

George H. Wolf; Mark S. T. Bukowinski

1988-01-01

393

Classical nucleation theory with a radius-dependent surface tension: A two-dimensional lattice-gas automata model  

NASA Astrophysics Data System (ADS)

The constant surface tension assumption of the Classical Nucleation Theory (CNT) is known to be flawed. In order to probe beyond this limitation, we consider a microscopic, two-dimensional Lattice-Gas Automata (LGA) model of nucleation in a supersaturated system, with model input parameters Ess (solid particle-to-solid particle bonding energy), Esw (solid particle-to-water bonding energy), ? (next-to-nearest-neighbor bonding coefficient in solid phase), and Cin (initial solute concentration). The LGA method has the advantages of easy implementation, low memory requirements, and fast computation speed. Analytical results for the system's concentration and the crystal radius as functions of time are derived and the former is fit to the simulation data in order to determine the equilibrium concentration. The “Mean First-Passage Time” technique is used to obtain the nucleation rate and critical nucleus size from the simulation data. The nucleation rate and supersaturation data are evaluated using a modification to the CNT that incorporates a two-dimensional radius-dependent surface tension term. The Tolman parameter, ?, which controls the radius dependence of the surface tension, decreases (increases) as a function of the magnitude of Ess (Esw), at fixed values of ? and Esw (Ess). On the other hand, ? increases as ? increases while Ess and Esw are held constant. The constant surface tension term of the CNT, ?0, increases (decreases) with increasing magnitudes of Ess (Esw) at fixed values of Esw (Ess) and increases as ? is increased. ?0 increases linearly as a function of the change in energy during an attachment or detachment reaction, |?E|, however, with a slope less than that predicted for a crystal that is uniformly packed at maximum density. These results indicate an increase in the radius-dependent surface tension, ?, with respect to increasing magnitude of the difference between Ess and Esw.

Hickey, Joseph; L'Heureux, Ivan

2013-02-01

394

Theory and economics of by-generation of electricity at city gate stations using a gas expander turbine  

SciTech Connect

The transmission pressure of pipeline gas entering a city-gate station offers an untapped energy source that gas-distribution companies can easily use to produce low-cost electricity. The high-pressure inlet gas can be heated, then isentropically expanded through a turbine that powers a generator and simultaneously reduces the gas pressure and temperature. The gas turboexpander behaves like a pinwheel in the line as the gas flow creates the rotary motion that drives the generator. The pressure and temperature differential that occurs across the inlet and outlet of the device can be held constant, functioning similarly to a standard regulator. The gas exiting the turbine is thus available at entry conditions for the gas-distribution system, while the electricity can be either used onsite or (in the case of a combination utility) fed into the network for electrical baseloading.

Bockert, B.J.

1980-01-01

395

Active stabilization to prevent surge in centrifugal compression systems  

NASA Astrophysics Data System (ADS)

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

396

Active identification and control of aerodynamic instabilities in axial and centrifugal compressors  

NASA Astrophysics Data System (ADS)

In this thesis, it is experimentally shown that dynamic cursors to stall and surge exist in both axial and centrifugal compressors using the experimental axial and centrifugal compressor rigs located in the School of Aerospace Engineering at the Georgia Institute of Technology. Further, it is shown that the dynamic cursors to stall and surge can be identified in real-time and they can be used in a simple control scheme to avoid the occurrence of stall and surge instabilities altogether. For the centrifugal compressor, a previously developed real-time observer is used in order to detect dynamic cursors to surge in real-time. An off-line analysis using the Fast Fourier Transform (FFT) of the open loop experimental data from the centrifugal compressor rig is carried out to establish the influence of compressor speed on the dynamic cursor frequency. The variation of the amplitude of dynamic cursors with compressor operating condition from experimental data is qualitatively compared with simulation results obtained using a generic compression system model subjected to white noise excitation. Using off-line analysis results, a simple control scheme based on fuzzy logic is synthesized for surge avoidance and recovery. The control scheme is implemented in the centrifugal compressor rig using compressor bleed as well as fuel flow to the combustor. Closed loop experimental results are obtained to demonstrate the effectiveness of the controller for both surge avoidance and surge recovery. The existence of stall cursors in an axial compression system is established using the observer scheme from off-line analysis of an existing database of a commercial gas turbine engine. However, the observer scheme is found to be ineffective in detecting stall cursors in the experimental axial compressor rig in the School of Aerospace Engineering at the Georgia Institute of Technology. An alternate scheme based on the amplitude of pressure data content at the blade passage frequency obtained using a pressure sensor located (in the casing) over the blade row is developed and used in the axial compressor rig for stall and surge avoidance and recovery. (Abstract shortened by UMI.)

Krichene, Assad

397

Influence of different centrifugation protocols on equine semen preservation.  

PubMed

Three experiments were conducted to evaluate the impact of centrifugation on cooled and frozen preservation of equine semen. A standard centrifugation protocol (600 x g for 10 min=CP1) was compared to four protocols with increasing g-force and decreased time period (600 x g, 1200 x g, 1800 x g and 2400 x g for 5 min for CP2, 3, 4, and 5, respectively) and to an uncentrifuged negative control. In experiment 1, the influence of the different CPs on sperm loss was evaluated by calculating the total number of sperm cells in 90% of the supernatant. Moreover, the effect on semen quality following centrifugation was assessed by monitoring several sperm parameters (membrane integrity using SYBR14-PI, acrosomal status using PSA-FITC, percentage total motility (TM), percentage progressive motility (PM) and beat cross frequency (BCF) obtained with computer assisted sperm analysis (CASA)) immediately after centrifugation and daily during chilled storage for 3 d. The use of CP1 resulted in a sperm loss of 22%. Increasing the centrifugation force to 1800 x g and 2400 x g for 5 min led to significantly lower sperm losses (7.4% and 2.1%, respectively; P<0.05). Compared to the uncentrifuged samples, centrifugation of semen resulted in a better sperm quality after chilled storage. There were minimal differences between the CPs although total motility was lower for CP2 than for the other treatments (P<0.005). In experiment 2, the centrifuged samples were cryopreserved using a standard freezing protocol and analyzed immediately upon thawing. Samples centrifuged according to CP2 resulted in a higher BCF (P<0.005), whereas CP3 and CP5 yielded a lower BCF (P<0.05) when compared to CP1. There were no post thaw differences between CP1 and CP4. In experiment 3, DNA integrity of the different samples was analyzed using TUNEL. Although DNA integrity decreased over time, CP had no impact. In conclusion, the loss of sperm cells in the supernatant after centrifugation can be substantially reduced by increasing the g-force up to 1800 x g or 2400 x g for a shorter period of time (5 min) compared to the standard protocol without apparent changes in semen quality, resulting in a considerable increase in the number of insemination doses per ejaculate. PMID:20207406

Hoogewijs, Maarten; Rijsselaere, Tom; De Vliegher, Sarne; Vanhaesebrouck, Emilie; De Schauwer, Catharina; Govaere, Jan; Thys, Mirjan; Hoflack, Geert; Van Soom, Ann; de Kruif, Aart

2010-03-06

398

Substrate Nanotexture and Hypergravity Through Centrifugation Enhance Initial Osteoblastogenesis  

PubMed Central

Mimicking the structural nanomolecular extracellular matrix with synthetically designed nanosized materials is a relatively new approach, which can be applied in the field of bone tissue engineering. Likewise, bone tissue-engineered constructs can be aided in their development by the use of several types of mechanical stimuli. In this study, we wanted to combine nanotextured biomaterials and centrifugation in one multifactorial system. Mesenchymal stem cells were isolated from rat bone marrow, and cultured on a nanogrooved polystyrene substrate (200-nm-wide pitch with a depth of 50?nm). Constant centrifugation of 10 g was applied to cells up to 7 days. Results showed that on a nanogrooved substrate osteoblast-like cells align parallel to the groove direction. Centrifugation of 10 g also affected cell morphology on a smooth surface. Moreover, cell alignment was significantly reduced for cells grown on nanogrooved substrates, which were subsequently subjected to centrifugation. Independently, both stimuli increased the number of cells after 7 days of culture. However, when both stimuli were combined, an additive effect on cell number was observed, followed by an enhanced effect on osteocalcin mRNA expression and matrix mineralization. In conclusion, biomaterial surface modification as well as centrifugation are effective means to enhance bone cell behavior, moreover, readily available to many tissue engineers.

Prodanov, Ljupcho; van Loon, Jack J.W.A.; te Riet, Joost; Walboomers, X. Frank

2013-01-01

399

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

400

Large colloidal crystals grown by centrifugation onto a template  

NASA Astrophysics Data System (ADS)

Colloidal crystals are commonly formed by sedimenting a colloidal solution at 1g onto a patterned template. Slow sedimentation was previously believed to be a requisite for growing large, perfect crystals without crossover to an amorphous sediment. By increasing the relative gravitational force applied to a monodisperse sample of hard-sphere, 1.55?m diameter silica colloids, we examined the effect of increased sedimentation velocity on the growth of face-centered cubic crystals on a (100) template. We varied relative centrifugal force up to 3000g, time of centrifugation, lattice parameter, and crystal thickness to assess their effect on crystal quality. Single crystals up to 52 ?m thick were grown for all centrifugation speeds. Crystal defects were predominantly stacking faults (bounded by partial dislocations), most of which formed after the critical thickness was reached. The critical thickness, which is a function of the lattice mismatch between crystal and template, was measured directly by varying the crystal thickness. Final stacking fault and vacancy concentrations were independent of centrifugal force and time. We also examined samples centrifuged onto other templates to elucidate the critical role of the template design in directing crystal versus glass formation.

Pennachio, Daniel; Jensen, Katharine; Weitz, David; Spaepen, Frans

2012-02-01

401

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

402

Estimating the amount of gas-hydrate using effective medium theory: a case study in the Blake Ridge  

NASA Astrophysics Data System (ADS)

Estimating the amount of gas-hydrate and free-gas is difficult in deep seas even with scientific coring and downhole measurements. Well data may be incompatible between holes of a site as well as with depth in the same hole. In this paper, we demonstrate an approach to estimate saturation of gas-hydrate from seismic velocities at any site where data set is limited. The study is carried out in the outer Blake Ridge, which is one of the most intensively studied regions of natural gas-hydrate occurrences and a very distinctive example of studying geophysical signatures of gas-hydrate and free-gas in deep marine sediments. Although, downhole measurements from both vertical seismic profiles (VSPs) and sonic logs provide the most accurate and direct measurements of velocity, only VSP velocities at Ocean Drilling Program (ODP) Sites 994, 995, and 997 on the Blake Ridge are used to estimate the saturation of gas-hydrate and free-gas as sonic logs at ODP sites are not reliable. Here we derive a general trend of the background velocity with depth using the porosity and mineralogy from coring at discrete depth intervals. Saturations of gas-hydrate and free-gas are then estimated from this background velocity using the effective medium modeling. The porosity and mineralogical compositions are taken from four different depths at Site 995, as data quality is the best in this hole. Average saturations of gas-hydrate and free-gas at three holes are estimated as 10-14 and 2-3%, respectively.

Ghosh, Ranjana; Sain, Kalachand; Ojha, Maheswar

2010-03-01

403

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

404

Biohazards Assessment in Large-Scale Zonal Centrifugation  

PubMed Central

A study was conducted to determine the biohazards associated with use of the large-scale zonal centrifuge for purification of moderate risk oncogenic viruses. To safely and conveniently assess the hazard, coliphage T3 was substituted for the virus in a typical processing procedure performed in a National Cancer Institute contract laboratory. Risk of personnel exposure was found to be minimal during optimal operation but definite potential for virus release from a number of centrifuge components during mechanical malfunction was shown by assay of surface, liquid, and air samples collected during the processing. High concentration of phage was detected in the turbine air exhaust and the seal coolant system when faulty seals were employed. The simulant virus was also found on both centrifuge chamber interior and rotor surfaces. Images

Baldwin, C. L.; Lemp, J. F.; Barbeito, M. S.

1975-01-01

405

Design Method for Single-Blade Centrifugal Pump Impeller  

NASA Astrophysics Data System (ADS)

The sewage pumps are demanded a high pump efficiency and a performance in passing foreign bodies. Therefore, the impeller used by these usages requires the large passed particle size (minimum particle size in the pump). However, because conventional design method of pump impeller results in small impeller exit width, it is difficult to be applied to the design of single-blade centrifugal pump impeller which is used as a sewage pump. This paper proposes a design method for single-blade centrifugal pump impeller. As a result, the head curve of the impeller designed by the proposed design method satisfied design specifications, and pump efficiency was over 62% more than conventional single-blade centrifugal pump impeller. By comparing design values with CFD analysis values, the suction velocity ratio of the design parameter agreed well with each other, but the relative velocity ratio did not agree due to the influence of the backflow of the impeller entrance.

Nishi, Yasuyuki; Fujiwara, Ryota; Fukutomi, Junichiro

406

Numerical Investigations of Slip Phenomena in Centrifugal Compressor Impellers  

NASA Astrophysics Data System (ADS)

This study systematically investigates the slip phenomena in the centrifugal air compressor impellers by CFD. Eight impeller blades for different specific speeds, wrap angles and exit blade angles are designed by compressor design software to analyze their flow fields. Except for the above three variables, flow rate and number of blades are the other two. Results show that the deviation angle decreases as the flow rate increases. The specific speed is not an important parameter regarding deviation angle or slip factor for general centrifugal compressor impellers. The slip onset position is closely related to the position of the peak value in the blade loading factor distribution. When no recirculation flow is present at the shroud, the variations of slip factor under various flow rates are mainly determined by difference between maximum blade angle and exit blade angle, ??max-2. The solidity should be of little importance to slip factor correlations in centrifugal compressor impellers.

Huang, Jeng-Min; Luo, Kai-Wei; Chen, Ching-Fu; Chiang, Chung-Ping; Wu, Teng-Yuan; Chen, Chun-Han

2013-03-01

407

Direction finding by hornets under gravitational and centrifugal forces.  

PubMed

The effect of centrifugal and gravitational forces whose resultant ranged between 26 degrees and 45 degrees on comb construction by hornet workers was assessed experimentally. Comb construction by hornets exposed to centrifugation at 1 to 2 days of age differed from that of hornets similarly exposed at 3 to 7 days of age. Juvenile hornets built their cells in the direction of the resultant force, whereas adults resisted the centrifugal force and tried to build in the direction of the gravitational force. Juveniles started their comb from the side walls, whereas adults started from the roof, as did nonspinning, control hornets. The findings suggest that hornets rapidly learn the gravitational force during the first days of life, and that they are aided by geometric cues of the breeding box to build in the direction of the force to which they had become habituated. PMID:1198099

Ishay, J; Sadeh, D

1975-11-21

408

Planarization process of BPSG: capillary vs. centrifugal/gravitational forces  

NASA Astrophysics Data System (ADS)

Film planarization process, of importance in semiconductor IC manufacturing, results from mutual competition between three forces: capillary, viscous, and gravitation. In this communication we compare, using simple geometric arguments, the order of magnitudes between the capillary force and a generalized centrifugal/gravitational force acting perpendicular to the surface. For patterns of sub-micron dimension and conditions similar to BPSG reflow and photo-resist coating we found that, within instrumental accessibility, the centrifugal term is much smaller than the capillary term. We conclude that the centrifugal/gravitational forces affect global patterns, i.e., with dimension larger than 1000 micrometers , while the capillary force dominates the sub-micro leveling process.

Perng, Baw-Ching; Linliu, Kung

2000-08-01

409

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

410

Experimental study on centrifugal pumps energy labelling in Iran  

NASA Astrophysics Data System (ADS)

The main goal of the present study was developing the energy label instruction for small centrifugal pumps. First the types of energy labels which are popular in the world especially three types of energy labels were introduced and discussed, two of which belongs to European United and the other one is assigned to Iran. Modified Iran labelling procedure with reasons was criticized and presented as a new approach in the present study. In the next step, e a standard test rig was established for testing of the small centrifugal pumps. A standard centrifugal pump named 32-160 and 32-200 was selected as the case studies. The selected pumps were test in the test rig and then labelled using selected methods. Finally the results considered and discoursed.

Derakhshan, S.; Abdolahnejad, E.; Buzari, M.

2012-11-01

411

Improvements in collimator design for verification of uranium enrichment in gaseous centrifuge header pipes of diameter 4.45 cm and 10.16 cm  

NASA Astrophysics Data System (ADS)

A technique that has been developed determines whether the process gas in a gaseous uranium centrifuge header pipe has an enrichment <= 20% or > 20%. Improvements have been made in the detector collimator to improve the ability to discriminate between gas and deposit in the header pipes. The new detector collimator has been characterized for pipes having inner diameters of 4.45 and 10.16 cm. A statistical analysis indicates that this new design is well suited to the smaller diameter pipe.

Close, D. A.; Pratt, J. C.

1987-06-01

412

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

413

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

414

Experimental and Theoretical Study on Circular Disk Particles Suspended in Centrifugal and Non-Centrifugal Force Environments  

NASA Astrophysics Data System (ADS)

Theoretical and experimental studies are performed on suspension particle motion in Centrifugal and Non-Centrifugal Force Environment, i.e., in both an axially rotating drum and a stable liquid tank. The particle velocity of circular disks is measured by PTV (Particle Tracking Velocimetry) method and is predicted by BBO (Basset-Boussinesq-Ossen) equation. It is found that (1) as time progresses, one side of the disk in the axially rotating drum is attracted toward the drum wall and its velocity is affected by the rotating speed, (2) when the particle moves in the Stokes' regime, its velocity is linearly increased with the distance from the center of the drum, (3) in contrast, the autorotation of the disk occurs in the non-centrifugal force field, and (4) the corresponding drag coefficient in the low Reynolds number region is in good agreement with the theoretical value of the sphere.

Torii, Shuichi; Watanabe, Yoshimi; Tanaka, Satoyuki; Yano, Toshiaki; Iino, Naoko

2008-02-01

415

Sedimentation of a two-dimensional colloidal mixture exhibiting liquid-liquid and gas-liquid phase separation: A dynamical density functional theory study  

NASA Astrophysics Data System (ADS)

We present dynamical density functional theory results for the time evolution of the density distribution of a sedimenting model two-dimensional binary mixture of colloids. The interplay between the bulk phase behaviour of the mixture, its interfacial properties at the confining walls, and the gravitational field gives rise to a rich variety of equilibrium and non-equilibrium morphologies. In the fluid state, the system exhibits both liquid-liquid and gas-liquid phase separation. As the system sediments, the phase separation significantly affects the dynamics and we explore situations where the final state is a coexistence of up to three different phases. Solving the dynamical equations in two-dimensions, we find that in certain situations the final density profiles of the two species have a symmetry that is different from that of the external potentials, which is perhaps surprising, given the statistical mechanics origin of the theory. The paper concludes with a discussion on this.

Malijevský, Alexandr; Archer, Andrew J.

2013-10-01

416

Dimethoxymethane-hydrogen chloride interaction: gas phase versus low-temperature behavior studied using matrix isolation infrared and density functional theory methods.  

PubMed

Premixing of dimethoxy methane (DMM) and hydrogen chloride (HCl) with Ar/N2 in the gas phase resulted in a nucleophilic substitution reaction and yielded products, cis-chloromethyl methyl ether (cis-CMME) and methanol. On the contrary, when DMM and HCl were separately codeposited in a low-temperature Ar matrix produced hydrogen-bonded alkoxy adduct, probably the intermediate in the gas phase nucleophilic substitution reaction. The formation of the alkoxy adduct was evidenced by the shifts in the vibrational frequencies of the DMM and HCl submolecules. The structure and energy of the alkoxy adduct were computed at the B3LYP/6-311++G** level of theory. The computations indicated only one minimum for the DMM-HCl adduct. The nucleophilic substitution reaction between DMM and HCl is prevented in the low-temperature matrix probably due to the cage effect in the matrix. PMID:23431963

Sundararajan, K; Ramanathan, N

2013-03-08

417

Theory for the effects of free gas in subsea formations on tidal pore pressure variations and seafloor displacements  

NASA Astrophysics Data System (ADS)

Loading of the seafloor by regional-scale pressure variations, such as those imposed by ocean tides, is supported by both the rock matrix and interstitial fluid. The nature of the partitioning of the support between the two depends primarily on the compressibility of the fluid and the compressibility and fluid-transport properties of the rock matrix. In this paper, we examine theoretically the influence of free gas on pore fluid compressibility, on the nature of time-dependent load partitioning, and on the consequent vertical rock deformation and seafloor displacement. An example is the gas trapped below deep-sea gas hydrate. We have derived an expression for the steady state compressibility of pore fluid considering the influence of gas solubility in water. The effect of gas solubility is seen to be important at low, such as tidal, loading frequencies and thus must be included when observations of tidally induced pore fluid pressure variations or seafloor displacements are used to constrain gas content. For very low gas concentrations ng (much less than 0.1%), the steady state fluid compressibility can be enhanced by gas solution/dissolution over the loading cycle by several factors at high ambient pressure and more than an order of magnitude at low ambient pressures (< 5 MPa). At ng > 2%, the fluid compressibility increases sensitively with ng and greatly affects the tidal response of the pore fluid pressure regardless of the solubility. Thus, with careful experimental design, tidally induced pore pressure variations may be used to detect very small amounts of free gas and constrain the quantity if ng > 2%. This method is complementary to using acoustic velocity to constrain the quantity of free gas, which works well in the ng = 0.2-2% range. We have also given an expression for the vertical deformation of subsea formations and hence of the seafloor displacement under tidal loading. The presence of free gas enhances tidally induced seafloor displacement, but the maximum effect is limited by the compressibility of the matrix frame. Given relatively low frame compressibility, tidally induced seafloor displacement is small, of the order of 1 mm, which is presently difficult to detect at tidal frequencies.

Wang, Kelin; Davis, Earl E.; van der Kamp, Garth

1998-06-01

418

Try magnetic gear pumps instead of sealless centrifugals  

SciTech Connect

Rotating equipment specialists often specify sealed centrifugal pumps since they are readily available, efficient, economical, and adaptable to changes in system pressure. Centrifugals have always been preferred for processing chemicals, while the niche for gear pumps has historically been for either viscous liquids in low-flow high-head applications or metering. However, rotating equipment specialists are becoming increasingly aware that when magnetic drives or canned motor pumps are required, gear pumps have advantages over centrifugals for some applications. These advantages are both in performance and cost. General selection guidelines are as follows. A sealless pump is needed when: the liquid has a viscosity over 10 cP at the range of differential pressures normal for ANSI centrifugals; the liquid has a viscosity of 0.8--5 cP at a differential pressure below 40--50 psi (100 ft); the liquid has a viscosity greater than 5 cP and the differential pressure is above 50 psi; and flow rates are below 40 gpm.

Nasr, A.M. [Liquiflo Equipment Co., Garwood, NJ (United States)

1996-03-01

419

Seal system development for large centrifugal pumps in arduous conditions.  

National Technical Information Service (NTIS)

This paper briefly describes the problems encountered with the drive shaft mechanical seal of a large centrifugal pump after the pump had been uprated. It then follows the development of a flexible throttle bush sealing system in case history format, deta...

D. Buchdahl D. Kempf R. Elliott

1992-01-01

420

Laboratory test tube centrifuge with longer working cycle  

Microsoft Academic Search

of the All-Union Scientific Research Institute of Pharmaceutical Chemistry [2], eliminates these deficiencies and makes it possible to carry out continuous filtration in test tubes, by continuous supply of the original suspension into the filtering test tubes and continuous withdrawal of the filtrate. Continuous precipitation into test tubes with unbroken bottoms canalso be carried out with this centrifuge. Figure 1

Z. B. Kristall; I. V. Danilenko

1968-01-01

421

Relationship Between Vibrations and Mechanical Seal Lift in Centrifugal Pumps.  

National Technical Information Service (NTIS)

A reduction of vibrations in mechanical seals increases the life of the seals in centrifugal pumps by minimizing fatigue damage. Mechanical seals consist of two smooth seal faces. one face is stationary with respect to the pump. The other rotates. Between...

D. Stefanko N. J. Jerald R. Leishear

2007-01-01

422

Centrifuge modelling of slope stabilisation using a discrete pile row  

Microsoft Academic Search

Discrete pile rows are an established technique for improving the stability of infrastructure slopes. However, the impact of pile spacing along the row is not clearly understood from a current design perspective in terms of the ultimate interaction capacity. A series of geotechnical centrifuge model tests were undertaken with the upper layer of a slope tending to fail and interact

B. S. Yoon; E. A. Ellis

2009-01-01

423

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

424

Centrifuge model study of an oil storage tank  

Microsoft Academic Search

Oil storage tanks placed on soft, compressible clay deposits were studied in two series of centrifugal model tests. The model consisted of a sand layer, an overconsolidated clay layer, and a normally consolidated clay layer. Different types of reinforcement arrangements were introduced in the sand layer to investigate the effectiveness of reinforcement. Two different loadings were applied to the model

1984-01-01

425

Centrifugal Fibers to the Retina of Octopus Vulgaris.  

National Technical Information Service (NTIS)

A modified Glees method has been used to demonstrate degeneration in the retina of Octopus after cutting optic nerves or devascularizing the optic lobe by cutting the optic tract. The massive degeneration considered to be due to damage of a centrifugal pa...

R. D. Lund

1965-01-01

426

Convection driven by centrifugal bouyancy in a rotating annulus  

Microsoft Academic Search

Drift rates and amplitudes of convection columns driven by centrifugal bouyancy in a cylindrical fluid annulus rotating about a vertical axis have been measured by thermistor probes. Conical top and bottom boundaries of the annular fluid region are responsible for the prograde Rossby wave like dynamics of the convection columns. A constant positive temperature difference between the outer and the

M. A. Azouni; E. W. Bolton; F. H. Busse

1985-01-01

427

Postoperative Mechanical Circulatory Support with Biomedicus Centrifugal Pump  

Microsoft Academic Search

Despite advances in surgical techniques, myocardial protection, and management protocols, approximately 1% of patients undergoing open heart operations still need mechanical circulatory support for severe cardiac dysfunction. The Biomedicus centrifugal pump, available in most cardiovascular centers, is a highly effective and relatively inexpensive system compared to other more sophisticated devices for the same purpose. Of 10 patients aged 5 to

Murat Mert; Atif Akcevin; Cenk E Yildiz; Kaya Suzer

2005-01-01

428

DEMONSTRATION BULLETIN: THE PLASMA CENTRIFUGAL FURNACE RETECH, INC.  

EPA Science Inventory

The plasma centrifugal furnace is a thermal technology which uses the heat generated from a plasma torch to decontaminate metal and organic contaminated waste. This is accomplished by melting metal-bearing solids and, in the process, thermally destroying organic contaminants. The...

429

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

430

Hydraulic Performance of a Multistage Array of Advanced Centrifugal Contactors  

SciTech Connect

The hydraulic characteristics of an advanced design centrifugal contactor array have been determined at the Savannah River Laboratory (SRL). The advanced design utilizes couette mixing (Taylor vortices) in the annulus between the rotating and stationary bowls. Excellent phase separation over a wide range of flow conditions was obtained. Interfaces within an entire eight-stage array were controlled with a single weir air pressure.

Hodges, M.E.

2001-05-29

431

Variable structure surge control for constant speed centrifugal compressors  

Microsoft Academic Search

This paper presents the application of active control of surge in constant speed centrifugal compressors based on the Moore–Greitzer (MG) model. Different controllers are developed for a compression system equipped with a close-coupled valve (CCV) and a throttle control valve (TCV). The combination of the two valves helps suppress surge and assists in overcoming the drawbacks of each valve when

Raef S. Shehata; Hussein A. Abdullah; Fayez F. G. Areed

2009-01-01

432

Brief Paper Positive feedback stabilization of centrifugal compressor surge  

Microsoft Academic Search

Stable operation of axial and centrifugal compressors is limited towards low mass 1ows due to the occurrence of surge. The stable operating region can be enlarged by active control. In this study, we use a control valve which is fully closed in the desired operating point and only opens to stabilize the system around this point. As a result, only

Frank Willems; W. P. M. H. Heemels; Anton A. Stoorvogel

433

Drive torque actuation in active surge control of centrifugal compressors  

Microsoft Academic Search

A novel approach to active surge control is presented for a centrifugal compressor driven by an electrical motor. The main idea of the paper is to use the drive itself for surge control. This eliminates the need for additional actuators, and has the potential of energy efficient operation. It is shown that previous unstable operating points to the left of

Jan Tommy Gravdahl; Olav Egeland; Svein Ove Vatland

2002-01-01

434

Active surge control of centrifugal compressors using drive torque  

Microsoft Academic Search

An approach to active surge control is presented. A centrifugal compressor driven by an electrical motor is studied, and the drive itself is used for surge control, thus eliminating the need for additional actuators. It is shown that by using the rotational speed of the motor as control, previous unstable operating points to the left of the surge line can

Jan Tommy Gravdahl; A. Egeland; Svein Ove Vatland

2001-01-01

435

A discussion of the factors affecting surge in centrifugal compressors  

Microsoft Academic Search

The process of surge in a centrifugal compressor has been studied and found to be dependent on a number of complex and often interrelated factors. A major factor defining surge in high-speed, vaned diffuser designs appears to be the flow in the semivaneless space. By developing work initiated by others it has been possible to propose some explanation of previously

R. L. Elder; M. E. Gill

1984-01-01

436

Reasons for centrifugal compressor surging and surge control  

Microsoft Academic Search

In examining the conventional modes of presenting axial and radial centrifugal-compressor operating envelopes, West Germany's Ruhrgas AG points out those conditions that cause compressors to surge. For axial or radial compressor installations, surging can be controlled only by shifting the operating envelope to the right, away from the surge limit line. One way to do this is to open the

Kolnsberg

1979-01-01

437

Modeling for surge control of centrifugal compressors: comparison with experiment  

Microsoft Academic Search

A dynamic model based on the thermo- and fluid-mechanic processes taking place in a centrifugal compressor is validated. The background for this is the need for an energy based model including the rotational speed as a state in order to perform energy based active surge control. The response of the model is compared with experimental results from the Energy Technology

Jan Tommy Gravdahl; Frank Willems; Bram de Jager; Olav Egeland

2000-01-01

438

The performance of a centrifugal compressor with high inlet prewhirl  

Microsoft Academic Search

The performance requirements of centrifugal compressors usually include a broad operating range between surge and choke. This becomes increasingly difficult to achieve as increased pressure ratio is demanded. In order to suppress the tendency to surge and extend the operating range at low flow rates, inlet swirl is often considered through the application of inlet guide vanes. To generate high

A. Whitfield; A. H. Abdullah

1998-01-01

439

Modeling and identification of centrifugal compressor dynamics with approximate realizations  

Microsoft Academic Search

This paper deals with the parameter identification of a model for the dynamic behavior of a large industrial centrifugal compression system. Experimental results are presented to evaluate a new approach for determining the parameters of a modified version of the well-known Greitzer model. This approach is based on an approximate realization algorithm that constructs an LTI model from step response

Jan van Helvoirt; Bram de Jager; Maarten Steinbuch; JPM Smeulers

2005-01-01

440

Surge control of the electrically driven centrifugal compressor  

Microsoft Academic Search

This paper presents a method of the energy efficiency and the operational performance improvement of the electrically driven air compression system. The key innovation of the proposed method-the active surge suppression of the centrifugal compressor by means of the speed control of the electrical drive has been experimentally validated. This method allows the load following operation of the compression system

K. O. Boinov; E. A. Lomonova; A. J. A. Vandenput; A. Tyagunov

2005-01-01

441

Simulation of centrifugal compressor transient performance for process plant applications  

Microsoft Academic Search

The development of a theoretical model capable of simulating centrifugal compressor transient performance (including compressor surge) is detailed. Simulation results from a Fortran computer program are compared with measured compressor transient data. Good simulation of compressor transients between stable operating points, and compressor presurge flow oscillations has been obtained. General application criteria are presented for the geometric distribution of model

I. MacDougal; R. L. Elder

1983-01-01

442

VISUALIZATION OF FLOW IN A TRANSONIC CENTRIFUGAL COMPRESSOR  

Microsoft Academic Search

Two kinds of measurement techniques by image processing were applied to visualize a flow in a transonic centrifugal compressor. One was a velocity field measurement at the inducer of the impeller using Particle Image Velocimetry (PIV) and the other was a pressure field measurement at the cascade diffuser using a Pressure Sensitive Paint (PSP) measurement technique. A shock wave in

Hiroshi Hayami; Masahiro Hojo; Shinichiro Aramaki

443

Centrifugal compressor controller for minimizing power consumption while avoiding surge  

Microsoft Academic Search

For use with a variable capacity centrifugal compressor driven by an electric motor, a controller is described for adjusting the capacity of the compressor to satisfy a demand, minimize electric power consumption and avoid a surge condition. The controller consists of: a. means for sensing an operating parameter that is indicative of the capacity of the compressor; b. means for

P. F. Haley; B. S. Junk; M. A. Renaud; P. C. Rentmeester

1987-01-01

444

Surge Control of the Electrically Driven Centrifugal Compressor  

Microsoft Academic Search

This paper presents a method of the energy efficiency and the operational performance improvement of the electrically driven air compression system. The key innovation of the proposed method-the active surge suppression of the centrifugal compressor by means of the speed control of the electrical drive has been experimentally validated. This method allows the load following operation of the compression system

Konstantin O. Boinov; Elena A. Lomonova; André J. A. Vandenput; Andrey Tyagunov

2006-01-01

445

Robust stabilization of a centrifugal compressor with spool dynamics  

Microsoft Academic Search

Issues of global stabilization of a centrifugal compressor with spool dynamics are presented. Control schemes are designed for systems with and without system uncertainty. While activating only the close-coupled valve or the throttle as the single control input, backstepping tools are first used to achieve global stability of the working equilibrium for systems without uncertainty. The uncertainties in the spool

Der-Cherng Liaw; Chau-Chung Song; Jeng-Tze Huang

2004-01-01

446

Noise Reduction in Centrifugal Fans by Use of Resonators.  

National Technical Information Service (NTIS)

The significant reduction of aerodynamically generated blade passage noise at the source by mounting a lambda/4 resonator at the cut-off lip on centrifugal fans is considered. While preserving the original cut-off lip geometry, the perforated mouth of the...

W. Neise G. H. Koopmann

1981-01-01

447

[Examination of the sample centrifugation time for emergency coagulation test].  

PubMed

The rapidity of coagulation testing is important for use as appropriate substitution therapy in patients with, or at risk of critical bleeding requiring massive transfusion. Whereas the ordinary method of coagulation testing is known to be slow, in a critically haemorrhaging patient, a rapid turnaround time of coagulation testing becomes indispensable. To find out if coagulation test results will be affected by a shortened centrifugation time, we measured PT (prothrombin time), APTT (activated partial thromboplastin time), FIB (fibrinogen) and PLT (platelet) in plasma, using different centrifugation times (10 min, 5 min, 3 min), and analyzed the measurements. We found that, whereas centrifugation time significantly affected the PLT count in plasma (10 min; 5.17 +/- 3.71 x 10(3)/microl, 5min; 28. +/- 26.9 x 10(3)/microl, 3min; 63.7 x 10(3)/microl), PT(10min; 14.6 +/- 5.76 sec, 5min; 14.7 +/- 5.84 sec, 3min; 14.9 +/- 6.40 sec), APTT (10min; 36.4 +/- 15.9 sec, 5min; 36.8 +/- 16.5 sec, 3min; 34.7 +/- 11.4 sec) and FIB(10min; 361 +/- 134 mg/dl, 5min; 356 +/- 132 mg/dl, 3min; 356 +/- 125 mg/dl) were not affected. These data suggest that shortening centrifugation time will have no significant effect on the value of PT, APTT and FIB, in an emergency situation. PMID:23383570

Watanabe, Yumi; Kawahara, Yoshie; Hanada, Daisuke; Nozawa, Keisuke; Tomoda, Yutaka; Kino, Shuichi

2012-11-01

448

Model based fault detection in a centrifugal pump application  

Microsoft Academic Search

A model based approach for fault detection in a centrifugal pump, driven by an induction motor, is proposed in this paper. The fault detection algorithm is derived using a combination of structural analysis, observer design and Analytical Redundancy Relation (ARR) design. Structural considerations on the system is used to divide it into two cascaded connected subsystems, giving an example on

C. S. Kallesoe; V. Cocquempot; R. Izadi-Zamanabadi

2006-01-01

449

The Role of Centrifugal Pumps in Water Supply  

Microsoft Academic Search

In arid and semi arid regions, ground water considers the major source for drinking and other uses, due to the shortage of rainfall and lack of surface water. Pumps are the suitable tools of lifting water from, the ground basins and wells, but, centrifugal pumps are the proper types for doing this job, because of their high pressures and velocities.

Oqla H. Dhaimat; Bassam A. Al-Helou

2004-01-01

450

STUDY ON CASING PERFORMANCES IN CENTRIFUGAL SLURRY PUMPS  

Microsoft Academic Search

The pump casing is the most expensive wear component of a centrifugal slurry pump. It determines to a large extent the hydraulic performance of the pump and plays a major role in the overall wear life of the unit.This paper suggests a new approach to compute the mixture velocity and solid particle dynamics in the casing, and on this basis

M. C. ROCO; G. R. ADDIE; R. VISINTAINER

1985-01-01

451

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...

452

Rapid determination of salicylate in serum on a centrifugal analyzer.  

PubMed

A bichromatic method is described for the determination of salicylate using a micro centrifugal analyzer. Salicylate was quantitated based on its reaction with ferric ion to produce a violet-colored complex. The method provides sample blanking and allows for rapid determination of salicylate levels in serum. PMID:6733896

Kwong, T; Adams, N; Young, N

1984-06-01

453

Influence of flotation tailings thickening on centrifugal flocculation performance  

Microsoft Academic Search

The dewatering and utilization of coal-cleaning wastes are important problems in connection with the control of air and water pollution in industrial areas and the recycling of production wastes in general. The most intractable technical problem is how to treat the very finely divided suspensions of flotation tailings to recover clean water for recycling and a handleable sludge. Centrifugal flocculation

V. V. Lyadov; A. V. Mikhailenkova; N. I. Yavorskaya; L. M. Gribova; A. V. Kovalchuk

1978-01-01

454

Pasteurization of Grapefruit Juice using a Centrifugal Ultraviolet Light Device  

Technology Transfer Automated Retrieval System (TEKTRAN)

The pharmaceutical industry uses UV devices to nonthermally inactivate viruses in liquids. To overcome the low penetration depth of UV in some liquids, such as serum plasma, thin films are formed by centrifugal force. Liquid foods also have low UV penetration depths. Studies are lacking on nontherma...

455

Liquid egg white pasteurization using a centrifugal UV irradiator  

Technology Transfer Automated Retrieval System (TEKTRAN)

Studies are lacking on UV nonthermal pasteurization of liquid egg white (LEW). The objective of this study was to inactivate Escherichia coli using a UV irradiator that centrifugally formed a thin film of LEW on the inside of a rotating cylinder. The LEW was inoculated with E. coli K12 to approximat...

456

Pasteurization of grapefruit juice using a centrifugal ultraviolet light irradiator  

Technology Transfer Automated Retrieval System (TEKTRAN)

The pharmaceutical industry uses UV irradiators to inactivate viruses in liquids without heat. The penetration depth of UV in some liquids, such as serum plasma, can be short. To overcome this, very thin films may be produced by centrifugal force, small diameter tubing, or other means. Many liquid f...

457

Fuzzy logic surge control in constant speed centrifugal compressors  

Microsoft Academic Search

This paper presents the application of fuzzy logic active control of surge in constant speed centrifugal compressors based on the Moore-Greitzer (MG) model. A compression system equipped with a close-coupled valve (CCV) and a throttle control valve (TCV) is investigated. Two fuzzy controllers are developed, one for each valve. The combination of the two valves proves helpful in suppressing surge

Raef S. Shehata; Hussein A. Abdullah; Fayez F. G. Areed

2008-01-01

458

World Centrifugal Sugar Situation Update, 1982/83.  

National Technical Information Service (NTIS)

World centrifugal sugar production for 1982/83 (Sept-Aug) is now estimated at 9816 million metric tons (raw value) compared with 98.5 million estimated last November and a revised 1981/82 production estimate of 100.7 million. Beet Sugar production in 1982...

1983-01-01

459

Producibility of brazed high-dimension centrifugal compressor impellers  

Microsoft Academic Search

The centrifugal compressor impeller is a high technology machine part and its manufacture is a demanding process. The paper shows that it is possible to join high-dimensional impellers parts by brazing. Various aspects of the construction and the brazing process of high-dimensional impellers have been considered and some modifications of the brazing have been proposed. The method was applied in

J Nowacki; P ?wider

2003-01-01

460

Countercurrent Chromatography with Flow-Through Coil Planet Centrifuge  

Microsoft Academic Search

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

Yoichiro Ito; Robert L. Bowman

1971-01-01

461

Method and apparatus for reducing axial thrust in centrifugal pumps  

Microsoft Academic Search

A control stator comprising a plurality of stationary vanes, ribs, or cavities is provided in a centrifugal pump having a shrouded impeller. The function of the control stator is to slow the swirl of fluid in the cavity between the casing and the impeller front shroud and thereby provide a very cost effective solution to the problem of excess axial

Alan S. Palmer; John W. Henry IV; John P. Kerr

1994-01-01

462

A Density Gradient Centrifugation Method for Separation of Peat  

Microsoft Academic Search

The conditions necessary for a laboratory—scale separation of the premaceral constituents of peat (i.e., the precursor to coal) are investigated. The method used is an isopycnic density centrifugation (DGC) technique aimed at isolating pure premacerals. This method, which is based on known density differences of various macerals, has been used successfully in coal separations but never with peats. The technique

E. M. Stack; G. R. Dyrkacz; P. G. Hatcher; A. D. Cohen

1997-01-01

463

Use minimum flow data to prolong centrifugal pump life  

Microsoft Academic Search

Environmental and safety concerns and, in the US, the consequences of failing of meet EPA regulations are intensifying efforts to improve the reliability of pumping equipment. A critical step toward achieving this goal is eliminating cavitation, and the resulting impeller and shaft vibrations, which, ultimately, cause seal and bearing failure. In centrifugal pumps, cavitation results when they run at very

1996-01-01

464

Simulation and optimization of centrifugal-planetary machining  

Microsoft Academic Search

Machining in free abrasive media is widely used in industry, on account of the universality and high productivity of these processes, as well as the formation of specific surface properties. This technique permits significant improvement in the operational characteristics of machine parts that depend on the roughness and the degree of surface plastic deformation. Centrifugal?planetary machining is most effective for

A. P. Sergiev; I. O. Matveev; D. A. Spitsyn

2007-01-01

465

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

466

Experimental use of a compact centrifugal pump and membrane oxygenator as a cardiopulmonary support system.  

PubMed

Compactness and high performance are the most important requirements for a cardiopulmonary support system. The Nikkiso (HPM-15) centrifugal pump is the smallest (priming volume; 25 ml, impeller diameter; 50 mm) in clinically available centrifugal pumps. The Kuraray Menox (AL-2000) membrane oxygenator, made of double-layer polyolefin hollow fiber, has a minimum priming volume (80 ml) and a low pressure loss (65 mm Hg at 2.0 L/min of blood flow) compared with other oxygenators. The aim of this study was to evaluate the performance of the most compact cardiopulmonary support system (total priming volume: 125 ml) in animal experiments. The cardiopulmonary bypass was constructed in a canine model with the Nikkiso pump and Menox oxygenator in comparison with a conventional cardiopulmonary support system. The partial cardiopulmonary bypass was performed for 4 h to evaluate the gas exchange ability, blood trauma, serum leakage, hemodynamics, and blood coagulative parameters. The postoperative plasma free hemoglobin level of the compact cardiopulmonary system was 29.5 +/- 10.21 mg/dl (mean +/- SD), which was lower than that of the conventional cardiopulmonary system, 48.75 +/- 27.39 mg/dl (mean +/- SD). This compact cardiopulmonary system provided the advantage in terms of reduction of the priming volume and less blood damage. These results suggested the possibility of miniaturization for the cardiopulmonary bypass support system in open-heart surgery in the near future. PMID:11119082

Suenaga, E; Naito, K; Cao, Z L; Suda, H; Ueno, T; Natsuaki, M; Itoh, T

2000-11-01

467

Determination of axial forces in centrifugal blowers in regulating their operating regime  

SciTech Connect

The authors examine the effect, on the axial force, of the most frequently used regulation methods in centrifugal blowers: throttling at suction and supercharging, variation of the angular velocity of the rotor, and the variation of the twist of the flow using the input regulating device (IRD). The investigations were conducted on a model of a single-stage centrifugal blower of natural gas equipped with a strain gauging system for measuring the axial load in the thrust bearing. An IRD of the axial type with the central body was used in regulation by varying the twist of the flow at the inlet into the rotor. A computer was used for averaging out the experimental data and integrating in respect to the surfaces of the rotor. Formation, by means of the IRD, of positive twisting of the flow in front of the rotor results in a considerably smaller reduction of axial force, especia-ly in regimes. Throttling in both supercharging and in suction increased the axial force.

Dovzhenko, V.N.; Bondarenko, G.A.; Eremenko, E.N.

1986-03-01

468

Proceedings of the International Conference Centrifuge 94 , Held in Singapore on 31 August-2 September 1994.  

National Technical Information Service (NTIS)

The Technical Committee, TC2, on Centrifuge Testing of the International Society of Soil Mechanics and Foundation Engineering (ISSMFE) is the body coordinating the worldwide efforts to develop and promote the use of centrifuge modeling in geotechnical eng...

C. F. Leung F. H. Lee T. S. Tan

1994-01-01

469

21 CFR 862.2140 - Centrifugal chemistry analyzer for clinical use.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 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)...

2010-04-01

470

Energy Tips - Pumping Systems. Select an Energy-Efficient Centrifugal Pump.  

National Technical Information Service (NTIS)

Centrifugal pumps handle high flow rates, provide smooth, nonpulsating delivery, and regulate the flow rate over a wide range without damaging the pump. Centrifugal pumps have few moving parts, and the wear caused by normal operation is minimal. They are ...

2005-01-01

471

Physical Modeling of Marginally Stable Tailings Dams Using Centrifuge Simulation Techniques.  

National Technical Information Service (NTIS)

The stability of a marginally stable tailings dam is investigated using centrifuge simulations and flow and stability analyses. The centrifuge simulations are conducted on Sandia's large radius machine using tailings from a coal mine. Pore pressure measur...

H. J. Sutherland R. P. Rechard A. A. Heckes

1984-01-01

472

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

473

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

474

Mean field kinetic theory of a classical electron gas in a periodic potential. II. Qualitative analysis of the mean-field solution in one dimension  

SciTech Connect

A qualitative analysis is made of the static and dynamic behavior of a one-dimensional classical electron gas in a periodic potential in the framework of a mean-field kinetic theory. The mean-field equations have been formally solved elsewhere in terms of the trajectories of one electron in the mean-field equilibrium potential, which determines the local electronic density. Taking advantage of the relative simplicity of the mean-field expressions in one dimension, we study the effects of the temperature upon the local electronic density, the static structure factor, and the spectrum of the fluctuations in the long-wavelength limit. At high temperatures, the system tends to behave like a homogeneous electron gas; however, the collective plasmon mode at zero wavenumber is damped and shifted below the plasma frequency. At low temperatures, the system behaves as an ensemble of independent electrons strongly localized in the neighborhood of the fixed ions that create the periodic potential; the plasmon mode then vanishes. The author consider the physical relevance of these predictions. They turn out to be quite reasonable, despite the failure of meanfield theory to predict the phase of the model.

Alastuey, A.

1987-11-01

475

THE AIR TURBINE FOR HIGH SPEED CENTRIFUGING OF BIOLOGICAL MATERIAL, TOGETHER WITH SOME OBSERVATIONS ON CENTRIFUGED EGGS  

Microsoft Academic Search

There are two main difficulties to be encountered in centrifuging living cells at high speed. First, they may be crushed against the bottom of the container by the high forces developed. This can be obviated by suspending the material in a niedium of graded density so that it comes to lie in a stratum of equal density and is completely

E. NEWTON HARVEY; Woods Hole

476

Study on Elastic Deformations of Grinding Wheels due to Centrifugal Forces  

Microsoft Academic Search

Grinding wheels are deformed by the effect of centrifugal forces. In this study, applying previously proposed mathematical model of grinding wheels, the elastic deformations due to centrifugal forces are analyzed. And, the analyzed elastic results are evaluated experimentally. From these results, it is clarified that the effect of centrifugal forces on the elastic deformations of grinding wheel can be analyzed

Takazo YAMADA; Hwa-Soo LEE

477

Cycle-powered short radius (1.9M) centrifuge: exercise vs. passive acceleration.  

PubMed

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. PMID:11540284

Greenleaf, J E; Gundo, D P; Watenpaugh, D E; Mulenburg, G M; Marchman, N; Looft-Wilson, R; Hargens, A R

1996-09-01

478

Centrifugally Driven Flow in Diverse Porous Media Over Wide-Ranging Moisture Conditions  

Microsoft Academic Search

Centrifugal force has been successfully applied to measurement of saturated and unsaturated hydraulic properties of soils and rock. The basis of most methods is to apply a steady flow of water, by either a constant head or a metering pump, to a sample in a centrifuge. If the centrifugal force is great enough to constitute the dominant driving force, measurements

J. R. Nimmo; M. C. Caputo

2003-01-01

479

Flow visualization and numerical modeling for the gradient freeze configuration during centrifugation  

Microsoft Academic Search

A visualization system was constructed for observation of buoyant convection in the gradient freeze configuration during centrifugation. The buoyant convective flow was observed in the tangential cross-section and two horizontal cross-sections of the test cell. Without centrifugation, the usual axisymmetric flow pattern with a toroidal vortex near the bottom of the test cell was observed. With centrifugation, the flow in

Peter Victorovich Skudarnov

1999-01-01

480

Effect of chronic centrifugation on the musculoskeletal system of the dog  

Microsoft Academic Search

Sixteen male Beagle dogs, 293 to 509 days old, were exposed almost continuously for 3 months to 2.0 G on a 7.9 meter radius centrifuge. The dogs were maintained on the centrifuge, by means of a specially designed automated waste disposal and life support system. As compared to the mean values of normal gravity controls, centrifuged dogs showed no differences

Eduard Amtmann; Jiro Oyama; Gerald L. Fisher

1976-01-01