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1

Iron nitride nanoparticles synthesized by inert gas condensation  

NASA Astrophysics Data System (ADS)

Inert gas condensation (IGC) is a highly versatile technique to synthesize monodisperse nanoparticles (NP). Earlier research done in our group on iron oxide nanoparticles and Fe- and Co- based fluids suggests that these NP's are well suited for magnetic drug delivery, however, their utility would be dramatically enhanced if they exhibited higher saturation magnetization. Iron-oxide nanoparticles are the most commonly studied system; however, the saturation magnetization (70-90 emu/g) is considerably lower than pure Fe (210 emu/g). Fe NPs tend to oxidize easily, so we are exploring Fe-N and Fe-C alternatives. We have used IGC to synthesize Fe-N nanoparticles (mean sizes ˜ 10-20 nm) using Fe deposition followed by gaseous nitrogenation, and via reactive inert-gas condensation. Post-deposition nitrogenation does not form Fe-N phases, nor protect the nanoparticles from oxidation. By reactive sputtering with varying relative concentration of N:Ar, we can produce FexN phases ranging from x=1 (non-magnetic ?-FeN) x=4. A systematic study of nitride phase formation as a function of Ar/N2 ratio during sputtering will be reported.

Shah, Prasanna; Ford, Brent; Dean, Andrew; Pelecky, Diandra

2009-10-01

2

Evaporation and Condensation of Large Droplets in the Presence of Inert Admixtures Containing Soluble Gas  

Microsoft Academic Search

In this study the mutual influence of heat and mass transfer during gas absorption and evaporation or condensation on the surface of a stagnant droplet in the presence of inert admixtures containing noncon- densable soluble gas is investigated numerically. The performed analysis is pertinent to slow droplet evapo- ration or condensation. The system of transient conjugate nonlinear energy and mass

T. Elperin; A. Fominykh; B. Krasovitov

2007-01-01

3

Superparamagnetic Nanocomposite of Silver\\/Iron-Oxide by Inert Gas Condensation  

Microsoft Academic Search

A superparamagnetic nanocomposite of silver and iron oxide was synthesized by gas condensation. The procedure involved (1) coevaporation of silver and iron, (2) in situ oxidation of iron particles, (3) in situ compaction, and (4) post-annealing in an inert or an oxidizing atmosphere. The magnetization plots against H\\/T fell on a single curve from room temperature to 160 K, thereby

Takao Yamamoto; Robert D. Shull; Prabhakar R. Bandaru; Frederic Cosandey; Horst W. Hahn

1994-01-01

4

Structural and optical properties of PbSe nanostructure thin films prepared by inert gas condensation  

NASA Astrophysics Data System (ADS)

Lead Selenide (PbSe) nanostructure thin films synthesized via inert gas condensation (IGC) technique. The structure of as-prepared PbSe nanostructure thin films, were studied using Grazing incident in-plane X-ray diffraction (GIIXD). The study reveals that all films crystallized in cubic structure. The particle size (Ps) of the films, were calculated from X-ray diffraction to be ~5, 8 and 11 nm for film thicknesses 20, 46 and 87 nm respectively which have been confirmed with those determined from transmission electron microscope (TEM) micrographs. The optical energy gap was found to be increases from 2.22 eV to 2.37 eV as particle size decreases from 11 nm to 5.5 nm. In addition, the band tail width increased with decreasing the particle size but the refractive index increases with increasing the particle size of the prepared films.

Mahdy, Manal A.; Mahdy, Iman A.; Mahmoud, E. A.

2014-05-01

5

Prevention of fog in the condensation of vapour from mixtures with inert gas, by a regenerative thermal process  

Microsoft Academic Search

In processing, vapours often have to be separated from mixtures mainly containing inert gas, as for example in the cleaning of exhaust air and the recovery of pollutant solvent vapours (volatile organic compounds, VOC). Whenever possible, condensation is applied for this task, since it is thermodynamically the most energy-efficient process. It can be carried out successfully, provided that the vapour

Stephan Kaufmann; Karl Hilfiker

1999-01-01

6

Precipitation in nanocrystalline Al-Ag prepared by inert gas condensation and by mechanical alloying  

SciTech Connect

One of the well-investigated model systems for precipitation reactions is the Al-Ag system on the Al-rich side of the phase diagram. When the supersaturated homogeneous alloy is aged within the miscibility gap, coherent Ag-rich regions form, the so-called Guinier-Preston (GP) zones. Upon further aging, Ag{sub 2}Al develops in two steps: first, precipitates of the semicoherent {gamma}{prime}-phase nucleate and grow. Second, incoherent precipitates of the equilibrium {gamma}-phase develop. There is general agreement in the literature that GP zones in Al-Ag are roughly spherical, but their exact shape and composition is the subject of ongoing research. GP-zones form homogeneously within the host matrix while Ag{sub 2}Al preferentially precipitates on defects such as dislocations and grain boundaries. Because of the high electron density contrast between Al and Ag, spatial variations of the alloy concentration on a scale of 1 nm--100 nm cause strong small-angle X-ray scattering (SAS). Therefore, SAS has been used extensively to study the decomposition of single-crystal or coarse-grained Al-Ag. In the present work, the precipitation of Ag in nanocrystalline Al-Ag is studied by small- and wide-angle X-ray scattering (WAS). Nanocrystalline samples were prepared by two different methods: inert gas condensation and mechanical alloying.

Hoeckel, P.G.; Weissmueller, J. [Univ. des Saarlandes, Saarbruecken (Germany)] [Univ. des Saarlandes, Saarbruecken (Germany)

1996-09-01

7

Purification of Inert Gas  

Microsoft Academic Search

The rate of removal of oxygen from inert gas by metallic getter is measured continuously, and the dilution model is adopted for explaining the rate of purification. The rate of removal of oxygen increases with flow rate. It is found that hydrogen and water vapor present in the inert gas contributes very effectively to reducing the oxygen partial pressure. The

Keiji NAITO; Toshihide TSUJI; Tsuneo MATSUI; Katsumi UNE

1974-01-01

8

Highly size-controlled synthesis of metal nanoclusters by inert-gas condensation for nano-devices.  

PubMed

Metal nanoclusters were fabricated by inert-gas condensation in a sputtering reactor. From transmission electron microscopy, it was confirmed that copper nanoclusters with a high degree of monodispersity in size of about 5 nm were successfully produced. The conductance of the percolated nanocluster film was measured. In order to incorporate nano-scale arrangement characterizations in nano-devices being operated in air, aging experiments of the specimen after long time in air were carried. Negative temperature coefficient of resistance suggests that surface native copper oxide in core-shell structured nanoclusters was mainly responsible for the conductance, because copper oxide is known as semiconductor. After aged at higher than 100 degrees C, the conductance at room temperature didn't return to the original value. This irreversible phenomenon might be due to coarsening and/or coalescence of copper nanoclusters. PMID:20359024

Kang, Il-Suk; Seo, Hyun-Sang; Kim, Deuk-Han; Lee, Taek-Yeong; Yang, Jun-Mo; Hwang, Wook-Jung; Ahn, Chi Won

2010-05-01

9

Energy barrier enhancement by weak magnetic interactions in Co/Nb granular films assembled by inert gas condensation  

NASA Astrophysics Data System (ADS)

A series of nanogranular Co/Nb samples has been prepared using an unfiltered beam of Co nanoparticles preformed by inert gas condensation. The preparation technique is shown to be a simple and effective method for fabricating, in a single deposition step, a sample series across which both particle size and concentration vary. We estimate the presence of weak interparticle (dipole-dipole) interactions ranging from 7 to 19% in strength (normalized to the median anisotropy energy barrier) across the present series. With the aim of elucidating the effect of such interactions on the blocking behavior of such nanogranular material, we have studied the field and temperature dependence of the magnetization in the films. For each sample, the temperature of the maximum in the zero-field-cooled magnetization curve (TMAX) is found to lie between the values of blocking (TB) and freezing (TF) temperature estimated from the experimentally determined particle size and concentration; i.e., TB

de Toro, J. A.; Gonzįlez, J. A.; Normile, P. S.; Muńiz, P.; Andrés, J. P.; López Antón, R.; Canales-Vįzquez, J.; Riveiro, J. M.

2012-02-01

10

Inert gas ion thruster  

NASA Technical Reports Server (NTRS)

Inert gas performance with three types of 12 cm diameter magnetoelectrostatic containment (MESC) ion thrusters was tested. The types tested included: (1) a hemispherical shaped discharge chamber with platinum cobalt magnets; (2) three different lengths of the hemispherical chambers with samarium cobalt magnets; and (3) three lengths of the conical shaped chambers with aluminum nickel cobalt magnets. The best argon performance was produced by a 8.0 cm long conical chamber with alnico magnets. The best xenon high mass utilization performance was obtained with the same 8.0 cm long conical thruster. The hemispherical thruster obtained 75 to 87% mass utilization at 185 to 205 eV/ion of singly charged ion equivalent beam.

Ramsey, W. D.

1980-01-01

11

Inert gas thrusters  

NASA Technical Reports Server (NTRS)

Inert gas thrusters have continued to be of interest for space propulsion applications. Xenon is of interest in that its physical characteristics are well suited to propulsion. High atomic weight and low tankage fraction were major factors in this choice. If a large amount of propellant was required, so that cryogenic storage was practical, argon is a more economical alternative. Argon was also the preferred propellant for ground applications of thruster technology, such as sputter etching and deposition. Additional magnetic field measurements are reported. These measurements should be of use in magnetic field design. The diffusion of electrons through the magnetic field above multipole anodes was studied in detail. The data were consistent with Bohm diffusion across a magnetic field. The theory based on Bohm diffusion was simple and easily used for diffusion calculations. Limited startup data were obtained for multipole discharge chambers. These data were obtained with refractory cathodes, but should be useful in predicting the upper limits for starting with hollow cathodes.

Kaufman, H. R.

1978-01-01

12

Mechanisms of Inert Gas Narcosis.  

National Technical Information Service (NTIS)

Experiments describing the mechanism of inert gas narcosis are reported. A strain of mice, genetically altered to increase susceptibility to botulin poisoning (synaptic response) appears to increase metabolic rates while breathing argon; this infers a gen...

1973-01-01

13

46 CFR 154.906 - Inert gas generators.  

Code of Federal Regulations, 2010 CFR

...Inert gas generators. The inert gas generator must: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device...station that alarms when the inert gas contains 5% or more oxygen by...

2010-10-01

14

Apparatus for manufacturing high pressure inert gas  

Microsoft Academic Search

At the present time, one of the biggest usages of inert gas is in the petroleum industry, wherein such gas is utilized in the recovery of petroleum. An apparatus is described for manufacturing high pressure inert gas utilizing hydrocarbon fuel. The gas is produced by the burning of hydrocarbon fuel in an internal combustion engine, the exhaust gases therefrom being

Gower

1971-01-01

15

Mechanisms of inert gas narcosis  

NASA Technical Reports Server (NTRS)

Experiments describing the mechanism of inert gas narcosis are reported. A strain of mice, genetically altered to increase susceptibility to botulin poisoning (synaptic response) appears to increase metabolic rates while breathing argon; this infers a genetically altered synaptic response to both botulin toxin and narcotic gases. Studies of metabolic depression in human subjects breathing either air or a 30% mixture of nitrous oxide indicate that nitrous oxide narcosis does not produce pronounced metabolic depression. Tests on mice for relative susceptibilities to narcosis and oxygen poisoning as a function of fatty membrane composition show that alteration of the fatty acid composition of phospholipids increases resistance to metabolically depressant effects of argon but bas no effect on nitrous oxide narcosis. Another study suggests that acclimatization to low tension prior to high pressure oxygen treatment enhances susceptibility of mice to convulsions and death; developing biochemical lesions cause CNS metabolite reductions and pulmonary damage.

1973-01-01

16

Inert gas transport in blood and tissues.  

PubMed

This article establishes the basic mathematical models and the principles and assumptions used for inert gas transfer within body tissues-first, for a single compartment model and then for a multicompartment model. From these, and other more complex mathematical models, the transport of inert gases between lungs, blood, and other tissues is derived and compared to known experimental studies in both animals and humans. Some aspects of airway and lung transfer are particularly important to the uptake and elimination of inert gases, and these aspects of gas transport in tissues are briefly described. The most frequently used inert gases are those that are administered in anesthesia, and the specific issues relating to the uptake, transport, and elimination of these gases and vapors are dealt with in some detail showing how their transfer depends on various physical and chemical attributes, particularly their solubilities in blood and different tissues. Absorption characteristics of inert gases from within gas cavities or tissue bubbles are described, and the effects other inhaled gas mixtures have on the composition of these gas cavities are discussed. Very brief consideration is given to the effects of hyper- and hypobaric conditions on inert gas transport. PMID:23737195

Baker, A Barry; Farmery, Andrew D

2011-04-01

17

Fast, Nonspattering Inert-Gas Welding  

NASA Technical Reports Server (NTRS)

Proposed welding technique combines best features of metal (other than tungsten)/inert-gas welding, plasma arc welding, and tungsten/inert-gas welding. Advantages include: wire fed to weld joint preheated, therefore fed at high speed without spattering; high-frequency energy does not have to be supplied to workpiece to initiate welding; size of arc gap not critical, power-supply control circuit adjusts voltage across gap to compensate for changes; only low gas-flow rate needed; welding electrode replaced easily as prefabricated assembly; external wire-feeding manipulator not needed; and welding process relatively forgiving of operator error.

Gilbert, Jeffrey L.

1991-01-01

18

Inflatable, Inert Gas-Purged, Welding Chamber.  

National Technical Information Service (NTIS)

An inflatable, inert-gas purged welding chamber assembly ideally suited for use in welding workpieces made of a metal (e.g., titanium), or of an alloy, which is susceptible to atmospheric contamination during welding. The welding chamber of the assembly i...

J. M. MacFarland

1981-01-01

19

Portable spectrometer monitors inert gas shield in welding process  

NASA Technical Reports Server (NTRS)

Portable spectrometer using photosensitive readouts, monitors the amount of oxygen and hydrogen in the inert gas shield of a tungsten-inert gas welding process. A fiber optic bundle transmits the light from the welding arc to the spectrometer.

Grove, E. L.

1967-01-01

20

46 CFR 154.908 - Inert gas generator: Location.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Inert gas generator: Location. 154.908 Section 154...Containment Systems Ā§ 154.908 Inert gas generator: Location. (a) Except as allowed...paragraph (b) of this section, an inert gas generator must be located in the main...

2013-10-01

21

Refractory metals welded or brazed with tungsten inert gas equipment  

NASA Technical Reports Server (NTRS)

Appropriate brazing metals and temperatures facilitate the welding or brazing of base metals with tungsten inert gas equipment. The highest quality bond is obtained when TIG welding is performed in an inert atmosphere.

Wisner, J. P.

1965-01-01

22

Municipal Landfill Gas Condensate,  

National Technical Information Service (NTIS)

New regulations relative to air emissions from municipal landfills may require the installation of gas collection systems at landfills. As landfill gas (LFG) is collected, water and other vapors in the gas condense in the system or are purposely removed i...

J. Briggs

1987-01-01

23

46 CFR 153.501 - Requirement for dry inert gas.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Requirement for dry inert gas. 153.501 Section 153.501 Shipping COAST...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment...

2013-10-01

24

46 CFR 153.500 - Inert gas systems.  

Code of Federal Regulations, 2013 CFR

... 5 2013-10-01 2013-10-01 false Inert gas systems. 153.500 Section 153.500 Shipping...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment...

2013-10-01

25

Inert gas diffusion in DLC–Si films  

Microsoft Academic Search

Inert-gas diffusion in DLC–Si films was studied by thermal effusion experiments. It is shown that the motion of inert gases in the films is controlled by diffusion, greatly depending on the size of the diffusing species. The results provide qualitative information on the microstructure size in agreement with the doorway diffusion model, in which the mechanical stiffness of the material

S. S. Camargo; J. C. Damasceno; W. Beyer

2002-01-01

26

Economic Feasibility of Inert Cushions in Underground Gas Storage.  

National Technical Information Service (NTIS)

The physical properties of storage reservoirs and the economics of three major processes for generating inert gases (cryogenic nitrogen, engine exhaust gas and boiler flue gases) have been investigated and compared to the current practice of using natural...

1980-01-01

27

33 CFR 157.164 - Use of inert gas system.  

Code of Federal Regulations, 2010 CFR

... § 157.164 Use of inert gas system. (a) The master...tank is crude oil washed, the oxygen content in the tank is measured...crude oil washed: (i) A gas or a mixture of gases with an oxygen content of 8 percent or...

2010-07-01

28

Heaterless ignition of inert gas ion thruster hollow cathodes  

NASA Technical Reports Server (NTRS)

Heaterless inert gas ion thruster hollow cathodes were investigated with the aim of reducing ion thruster complexity and increasing ion thruster reliability. Cathodes heated by glow discharges are evaluated for power requirements, flowrate requirements, and life limiting mechanisms. An accelerated cyclic life test is presented.

Schatz, M. F.

1985-01-01

29

Spectral analysis of inert gas elimination data: resolution limits.  

PubMed

A new method of analyzing inert gas data for recovery of the pulmonary ventilation-perfusion ration (VA/Q) distribution is proposed. It is shown that the conventional inert gas elimination equation takes the form of a convolution integral, and the relationship between VA/Q distribution and inert gas elimination resembles that of a noncausal low-pass filter with infinite zero-frequency gain. With the use of this formulation, characteristic features of VA/Q distribution may be represented in the frequency domain in terms of the corresponding energy spectrum. It is shown that the lack of resolution associated with finite data samples and measurement error is caused by distortions in the high-frequency contents of the resulting VA/Q distribution. With six inert gases, the technique cannot resolve a log SD less than 0.21 decade and a modal separation less than 0.87 decade. In the presence of measurement error, the degree of resolution is even less. It is suggested that for maximum resolution the number of discrete and duplicate data samples should be chosen so that the resulting noise and sampling cutoff frequencies are approximately equal. PMID:3379004

Poon, C S

1988-04-01

30

Combustion of Cr 2 O 3 + Al powder mixtures in a coflow of inert gas: 5. Effect of green density  

Microsoft Academic Search

Combustion of Cr2O3 + Al powder mixtures in a coflow of inert gas (Ar) was investigated upon variation in green density in the presence\\/absence\\u000a of blowing agents (borax, baking soda). The results were rationalized in terms of the convection-conduction theory for combustion\\u000a in heterogeneous condensed systems.

B. S. Seplyarskii; G. B. Brauer; A. G. Tarasov

2009-01-01

31

Condensed Explosive Gas Dynamic Laser.  

National Technical Information Service (NTIS)

The condensed explosive of a gas dynamic laser is a condensed mixture of one or more nonhydrogenous organic explosive compounds, such as TNM, with a sufficient amount of aluminum or zirconium powder to supply energy to the products so that a temperature o...

J. Hershkowitz M. Y. D. Lanzerotti

1978-01-01

32

Inert gas analysis of ventilation-perfusion matching during hemodialysis.  

PubMed Central

The mechanism of hypoxemia during hemodialysis was investigated by the multiple inert gas elimination technique in anesthetized, paralyzed, mechanically ventilated dogs. Profound leukopenia occurred in the first hour of a 2-h hemodialysis with a cuprophan membrane and dialysate that contained acetate. Arterial partial pressure of O2 and CO2 and oxygen consumption remained unchanged during dialysis. Pulmonary carbon dioxide elimination and lung respiratory exchange ratio decreased with the initiation of dialysis, remained depressed throughout the duration of dialysis, and returned to predialysis levels after the cessation of dialysis. Cardiac output diminished during dialysis but did not return to base-line levels after dialysis. Multiple indices calculated from inert gas analysis revealed no ventilation-perfusion mismatching during dialysis. The shunt and perfusion to regions of low alveolar ventilation-to-perfusion ratio (VA/Q) were unchanged during dialysis. There was no change in the mean or standard deviation of the profile of the percentage of total perfusion to regions of the lung that had VA/Q near 1.0; nor was there any increase in the directly calculated arterial-alveolar partial pressure differences for the inert gases during dialysis. Dead space became mildly elevated during dialysis. These results show that during dialysis with controlled ventilation there is no ventilation-perfusion mismatching that leads to hypoxemia. During spontaneous ventilation any hypoxemia must occur due to hypoventilation secondary to the CO2 exchange by the dialyzer and subsequent reduction in pulmonary CO2 exchange.

Ralph, D D; Ott, S M; Sherrard, D J; Hlastala, M P

1984-01-01

33

Nuclear Technology. Course 28: Welding Inspection. Module 28-3, Tungsten Inert Gas (TIG), Metal Inert Gas (MIG) and Submerged Arc Welding.  

ERIC Educational Resources Information Center

This third in a series of ten modules for a course titled Welding Inspection presents the apparatus, process techniques, procedures, applications, associated defects, and inspection for the tungsten inert gas, metal inert gas, and submerged arc welding processes. The module follows a typical format that includes the following sections: (1)…

Espy, John

34

Synthesis of nanocrystalline Mn-oxides by gas condensation  

Microsoft Academic Search

The preparation of nanocrystalline (n-) Mn-oxides has been investigated. The oxides were obtained by oxidation of n-Mn metal, prepared by inert gas condensation, in air and in oxygen at different temperatures and times. Differential thermal analysis revealed a broad exothermic peak with a maximum at 596°C, while thermogravimetry showed the adsorption of O2 between 580 and 700°C. XRD diffractograms, performed

L Dimesso; L Heider; H Hahn

1999-01-01

35

Cytogenetic studies of stainless steel welders using the tungsten inert gas and metal inert gas methods for welding.  

PubMed

Cytogenetic damage was studied in lymphocytes from 23 welders using the Tungsten Inert Gas (TIG), and 21 welders using the Metal Inert Gas (MIG) and/or Metal Active Gas (MAG) methods on stainless steel (SS). A matched reference group I, and a larger reference group II of 94 subjects studied during the same time period, was established for comparison. Whole blood conventional cultures (CC), cultures in which DNA synthesis and repair were inhibited (IC), and the sister chromatid exchange (SCE) assay were applied in the study. For the CC a statistically significant decrease in chromosome breaks and cells with aberrations was found for both TIG/SS and MIG/MAG/SS welders when compared with reference group II. A non-significant decrease was found for the corresponding parameters for the two groups of welders when compared with their matched referents. A statistically significant negative association was found between measurements of total chromium (Cr) in inhaled air and SCE, and a weaker negative correlation with hexavalent Cr (Cr(VI)) in air. In conclusion, no cytogenetic damage was found in welders exposed to the TIG/SS and MIG/MAG/SS welding fumes with low content of Cr and Ni. On the contrary, a decline in the prevalence of chromosomal aberrations was indicated in the TIG/SS and MIG/MAG/SS welders, possibly related to the suggested enhancement of DNA repair capacity at slightly elevated exposures. PMID:7885396

Jelmert, O; Hansteen, I L; Langård, S

1995-03-01

36

Condensing from Vapor-Gas Mixtures.  

National Technical Information Service (NTIS)

Designing condensers for vapor-gas mixtures is far more complex than for vapors alone. This simplified design method eliminates the old trial-and-error procedures. Condensation of vapor from a vapor-gas mixture where the gas does not condense is quite dif...

F. Votta

1964-01-01

37

Odorization of inert gas for occupational safety: psychophysical considerations.  

PubMed

Odorization of inert gas can serve to warn workers in an enclosed space about gas leaking into the space. This psychophysical investigation, performed under conditions of directed attention, examined two candidates for possible odorization of argon:pyridine and cis-3-hexen-1-ol. Detection thresholds for pyridine and cis-3-hexen-1-ol in argon were 106 ppb and 19 ppb, respectively. Practice over four days yielded modest improvement in the detection of both odorants. For cis-3-hexen-1-ol, smokers had marginally lower thresholds than nonsmokers and older participants had slightly higher thresholds than younger participants. Gender, smoking status and age had no reliable influence on threshold for pyridine. This outcome indicated desirable perceptual stability for pyridine. Additional experiments dealt with the perceived intensity of pyridine and cis-3-hexen-1-ol over time in the realistic setting of an environmental chamber. Visitors to the chamber and occupants in the chamber assessed perceived magnitude at 5-min intervals for up to 60 min during injections of odorized argon into the chamber. Participants could gauge and track the concentration of pyridine much better than that of cis-3-hexen-1-ol. This held true for occupants almost to the same degree as visitors, though occupants inevitably exhibited some olfactory adaptation. Hence, the suprathreshold measurements also gave strong relative endorsement to pyridine. Calculations based on the experimental results indicated that odorization of the inert gas stream with 3 to 10 ppm (v/v) pyridine should suffice to warn occupants or visitors of an argon buildup of any severity. Field studies should permit a definitive judgment of the best concentration to use in practice. PMID:3031973

Cain, W S; Leaderer, B P; Cannon, L; Tosun, T; Ismail, H

1987-01-01

38

Development of advanced inert-gas ion thrusters  

NASA Technical Reports Server (NTRS)

Inert gas ion thruster technology offers the greatest potential for providing high specific impulse, low thrust, electric propulsion on large, Earth orbital spacecraft. The development of a thruster module that can be operated on xenon or argon propellant to produce 0.2 N of thrust at a specific impulse of 3000 sec with xenon propellant and at 6000 sec with argon propellant is described. The 30 cm diameter, laboratory model thruster is considered to be scalable to produce 0.5 N thrust. A high efficiency ring cusp discharge chamber was used to achieve an overall thruster efficiency of 77% with xenon propellant and 66% with argon propellant. Measurements were performed to identify ion production and loss processes and to define critical design criteria (at least on a preliminary basis).

Poeschel, R. L.

1983-01-01

39

46 CFR 153.462 - Static discharges from inert gas systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Static discharges from inert gas systems. 153.462 Section 153.462 Shipping...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment...

2013-10-01

40

Inert-gas welding and brazing enclosure fabricated from sheet plastic  

NASA Technical Reports Server (NTRS)

Custom-fabricated plastic bag maintains an inert-gas atmosphere for welding and brazing certain metals. The bag fits over part of the workpieces and the welding and brazing tools. It is also used for metal brazing and fusion plating which require an inert-gas atmosphere.

Wisner, J. P.

1965-01-01

41

Visual/vestibular effects of inert gas narcosis.  

PubMed

Divers breathing compressed air at depths beyond 30 m experience a type of behavioural impairment known as inert gas narcosis. This condition degrades performance on a wide range of tasks and has the potential to compromise safety. Symptoms associated with narcosis include slowed response time, amnesia, and euphoria. Studies have also found disturbances to mechanisms regulating ocular control in response to vestibular stimulation; however, these experiments have been limited to very low frequency head movement (0.2 Hz). Thus, to further examine the effects of narcosis on visual/vestibular mechanisms, the vestibular ocular reflex (VOR) was assessed across a range of higher frequencies more representative of natural head movement (2.0-4.7 Hz). Seven subjects were tested prior to, during and after exposure to narcosis which was induced using 30% nitrous oxide. Standard room air was breathed as a control. The results indicated that narcosis decreased the velocity of compensatory eye movements in response to head rotation (decrease in VOR-gain), with more pronounced decreases occurring at the higher frequencies. The lag between eye and head position (phase lag) was also decreased by nitrous oxide; an effect that was again more pronounced at higher frequencies. These results indicate that narcosis disrupts ocular regulatory mechanisms which help to stabilize images on the retina during head movement. PMID:8365388

Hamilton, K; Laliberte, M F; Heslegrave, R; Khan, S

1993-08-01

42

Simplified power processing for inert gas ion thrusters  

NASA Technical Reports Server (NTRS)

Significant simplifications to power processors for inert gas ion thrusters in the 1 to 5 kW range have been identified. They include elimination of all but three power supplies - one each for the neutralizer, main discharge, and beam. The neutralizer and discharge power supplies would provide both cathode heating and plasma generating functions. This dual-use power supply concept was validated via integration tests with a 30 cm diameter xenon ion thruster. The beam/accelerator power supply would have positive and negative outputs to allow a single power supply to provide both functions. The discharge and beam power supplies would incorporate full-bridge inverters similar to those proven for flight-ready arcjet propulsion systems. Operation of this simplified power processing scheme at an inverter frequency of 50 kHz results in a projected power processor design with low mass and high efficiency. A 2 kW reference point design has estimated values of specific mass of 5.4 kg/kW and an efficiency of 93 percent.

Rawlin, V. K.; Pinero, L. R.; Hamley, J. A.

1993-01-01

43

Oxygen carrier for gas chromatographic analysis of inert gases in propellants  

NASA Technical Reports Server (NTRS)

Gas chromatographic determination of small quantities of inert gases in reactive propellants is discussed. Operating conditions used for specific analyses of helium in diborane and nitrogen in oxygen difluoride are presented in tabular form.

Cannon, W. A.

1972-01-01

44

Problems in the modelling of inert gas kinetics.  

PubMed

The models used to describe the kinetics of inert gases during underwater diving are inadequate. Medical practitioners and scientists interested in such diving have attempted to quantitatively describe the behaviour of nitrogen in compressed air diving since 1908, with little success. The problems encountered during this diving research are relevant to anaesthesia theory and practice. PMID:7793591

Gorman, D

1995-04-01

45

Noninvasive Cardiac Output Determination for Children by the Inert Gas-Rebreathing Method  

Microsoft Academic Search

Standard methods for determination of cardiac output (CO) are either invasive or technically demanding. Measurement of CO\\u000a by the inert gas–rebreathing (IGR) method, applied successfully in adults, uses a low-concentration mixture of an inert and\\u000a a blood-soluble gas, respectively. This study tested the feasibility of this method for determining CO during exercise for\\u000a pediatric patients with complete congenital atrioventricular block

Gesa Wiegand; Gunter Kerst; Winfried Baden; Michael Hofbeck

2010-01-01

46

Operation of the J-series thruster using inert gas  

NASA Technical Reports Server (NTRS)

Electron bombardment ion thrusters using inert gases are candidates for large space systems. The J-Series 30 cm diameter thruster, designed for operation up to 3 k-W with mercury, is at a state of technology readiness. The characteristics of operation with xenon, krypton, and argon propellants in a J-Series thruster with that obtained with mercury are compared. The performance of the discharge chamber, ion optics, and neutralizer and the overall efficiency as functions of input power and specific impulse and thruster lifetime were evaluated. As expected, the discharge chamber performance with inert gases decreased with decreasing atomic mass. Aspects of the J-Series thruster design which would require modification to provide operation at high power with insert gases were identified.

Rawlin, V. K.

1982-01-01

47

Lifting of heavy oil with inert-gas-operated chamber pumps  

SciTech Connect

A description is given of an unconventional gas lift system which can replace rod pumping for shallow (<3,000 ft.) heavy oil production. The heart of this system is an insert chamber downhole, whose only moving parts are two standing valves. Produced fluid entering the chamber is periodically expelled into a production annulus by pressurized gas injected from the surface down a small injection string. Natural gas, inert gas, or even air can be used for pumping. This study analyzes the operation of the chamber lifting system and shows how to optimize the system design and the operating variables to obtain maximum production at minimum cost. With the close spacing of thermal wells (2-5 acres), the combination of a single inert gas generator and associated compressor to supply a large number of wells equipped with chamber pumps is feasible. Several types of inert gas generators are described. 7 refs.

Dewan, J.T.; Elfarr, J.

1981-01-01

48

INVESTIGATION ON THE OSCILLATING GAS FLOW ALONG AN INERTANCE TUBE BY EXPERIMENTAL AND CFD METHODS  

SciTech Connect

To investigate the oscillating gas flow along an inertance tube used in pulse tube coolers, a CFD model is set up for FLUENT and an experimental measuring cell is designed and optimized by CFD results. Some characteristics of oscillating flow are demonstrated and discussed. Then, the flow status along an inertance tube is measured by the optimized measuring cell. The experimental results validate the simulating results.

Chen Houlei; Zhao Miguang; Yang Luwei; Cai Jinghui; Hong Guotong; Liang Jingtao [Technical Institute of Physics and Chemistry, CAS, Beijing, 100190 (China)

2010-04-09

49

Light-gas effect on steam condensation  

SciTech Connect

In a postulated reactor accident, the loss of coolant results in a release of high-temperature steam into the containment. Under these circumstances steam condensation onto containment walls provides an effective mechanism of energy removal. However, the presence of noncondensable gas is known to degrade the heat transfer. It has also been found that the introduction of a light noncondensable gas has little effect until sufficient quantities are present to disrupt the buoyancy forces. Our investigation shows the dramatic effect of high concentrations of light gas decreasing steam condensation rates under anticipated accident conditions for AP600, with helium as the simulant for hydrogen.

Anderson, M.H.; Corradini, M.L. [Univ. of Wisconsin, Madison, WI (United States); Herranz, L.E. [Centro de Investigcaiones Energeticas Medioambientales y Tecnologicas, Madrid (Spain)

1997-12-01

50

Carbothermic Reduction of Chromite Ore Under Different Flow Rates of Inert Gas  

NASA Astrophysics Data System (ADS)

The reduction of chromite ore with carbon has been studied extensively in many laboratories. Inert gases have been used in these investigations to control the experimental conditions. However, little information is available in the literature on the influence of the gas flow rate on the rate of reduction. Experiments were carried out to study the influence of the flow rate of inert gas on the reducibility of chromite ore. The experiments showed that the rate of reduction increased with the increasing flow rate of argon up to an optimum flow rate. At higher flow rates, the rate of reduction decreased. The influence of the proportion of reductant on the extent of reduction depended on the rate of flow rate of inert gas. The experimental results are interpreted on the basis of a model that postulates that the mechanism of reduction changes with the flow rate of argon.

Chakraborty, Dolly; Ranganathan, S.; Sinha, S. N.

2010-02-01

51

Continuous injection of an inert gas through a drill rig for drilling into potentially hazardous areas  

DOEpatents

A drill rig for drilling in potentially hazardous areas includes a drill having conventional features such as a frame, a gear motor, gear box, and a drive. A hollow rotating shaft projects through the drive and frame. An auger, connected to the shaft is provided with a multiplicity of holes. An inert gas is supplied to the hollow shaft and directed from the rotating shaft to the holes in the auger. The inert gas flows down the hollow shaft, and then down the hollow auger and out through the holes in the bottom of the auger into the potentially hazardous area. 3 figs.

McCormick, S.H.; Pigott, W.R.

1997-12-30

52

Continuous injection of an inert gas through a drill rig for drilling into potentially hazardous areas  

DOEpatents

A drill rig for drilling in potentially hazardous areas includes a drill having conventional features such as a frame, a gear motor, gear box, and a drive. A hollow rotating shaft projects through the drive and frame. An auger, connected to the shaft is provided with a multiplicity of holes. An inert gas is supplied to the hollow shaft and directed from the rotating shaft to the holes in the auger. The inert gas flows down the hollow shaft, and then down the hollow auger and out through the holes in the bottom of the auger into the potentially hazardous area.

McCormick, Steve H. (Idaho Falls, ID); Pigott, William R. (Idaho Falls, ID)

1997-01-01

53

Role of Carbon Dioxide in Inert Gas Narcosis.  

National Technical Information Service (NTIS)

The role of carbon dioxide and oxygen in high pressure narcosis was studied by exposing animals to hyperbaric conditions while maintaining them normoxic and normocapnic. Chickens were the experimental animals. Heated, humidified gas entered the lung via a...

H. S. Weiss

1977-01-01

54

Inert gas rejection device for zinc-halogen battery systems  

DOEpatents

An electrolytic cell for separating chlorine gas from other (foreign) gases, having an anode, a cathode assembly, an aqueous electrolyte, a housing, and a constant voltage power supply. The cathode assembly is generally comprised of a dense graphite electrode having a winding channel formed in the face opposing the anode, a gas impermeable (but liquid permeable) membrane sealed into the side of the cathode electrode over the channel, and a packing of graphite particles contained in the channel of the cathode electrode. The housing separates and parallelly aligns the anode and cathode assembly, and provides a hermetic seal for the cell. In operation, a stream of chlorine and foreign gases enters the cell at the beginning of the cathode electrode channel. The chlorine gas is dissolved into the electrolyte and electrochemically reduced into chloride ions. The chloride ions disfuse through the gas impermeable membrane, and are electrochemically oxidized at the anode into purified chlorine gas. The foreign gases do not participate in the above electrochemical reactions, and are vented from the cell at the end of the cathode electrode channel.

Hammond, Michael J. (Sterling Heights, MI); Arendell, Mark W. (Warren, MI)

1981-01-01

55

Study on DC Double Pulse Metal Inert Gas (MIG) Welding of Magnesium Alloy  

Microsoft Academic Search

This article gives a preliminary research on direct current (DC) double pulse metal inert gas (MIG) welding of magnesium alloys. It will be an effort for broadening the application of this new MIG welding process. The unique parameters of DC double pulse MIG welding are selected to investigate their effects on weld bead geometry size and appearance of AZ31B Mg

Zhaodong Zhang; Xiangyu Kong

2012-01-01

56

Relationship Between Arc Voltage Current and Arc Length in TIG (Tungsten Inert Gas) Welding.  

National Technical Information Service (NTIS)

The report investigates the relationship between arc voltage, arc length and current in Tungsten Inert Gas welding. It concludes that using these parameters is not the best method to use in developing a system to control the arc length. (Copyright (c) Cen...

P. N. Drew R. T. Deam

1989-01-01

57

TIG (Tungsten Inert Gas) Welding for Dry Storage Containers,  

National Technical Information Service (NTIS)

The single pass plasma welding technique, developed to meet the original GDCD specification for sealing the AGR dry storage containers, has been shown to contain ineradicable gas pores of up to two-thirds of the wall thickness at the points of keyhole clo...

C. J. Smith E. J. Morgan-Warren

1987-01-01

58

Inert gas clearance from tissue by co-currently and counter-currently arranged microvessels  

PubMed Central

To elucidate the clearance of dissolved inert gas from tissues, we have developed numerical models of gas transport in a cylindrical block of tissue supplied by one or two capillaries. With two capillaries, attention is given to the effects of co-current and counter-current flow on tissue gas clearance. Clearance by counter-current flow is compared with clearance by a single capillary or by two co-currently arranged capillaries. Effects of the blood velocity, solubility, and diffusivity of the gas in the tissue are investigated using parameters with physiological values. It is found that under the conditions investigated, almost identical clearances are achieved by a single capillary as by a co-current pair when the total flow per tissue volume in each unit is the same (i.e., flow velocity in the single capillary is twice that in each co-current vessel). For both co-current and counter-current arrangements, approximate linear relations exist between the tissue gas clearance rate and tissue blood perfusion rate. However, the counter-current arrangement of capillaries results in less-efficient clearance of the inert gas from tissues. Furthermore, this difference in efficiency increases at higher blood flow rates. At a given blood flow, the simple conduction-capacitance model, which has been used to estimate tissue blood perfusion rate from inert gas clearance, underestimates gas clearance rates predicted by the numerical models for single vessel or for two vessels with co-current flow. This difference is accounted for in discussion, which also considers the choice of parameters and possible effects of microvascular architecture on the interpretation of tissue inert gas clearance.

Lu, Y.; Michel, C. C.

2012-01-01

59

Comparison of Inert-Gas-Fusion and Modified Kjeldahl Techniques for Determination of Nitrogen in Niobium Alloys.  

National Technical Information Service (NTIS)

This report compares results obtained for the determination of nitrogen in a selected group of niobium-base alloys by the inert-gas-fusion and the Kjeldahl procedures. In the inert-gas-fusion procedure the sample is heated to approximately 2700 C in a hel...

E. J. Merkle J. W. Graab W. F. Davis

1974-01-01

60

Influence of inert gas species on the growth of silver and molybdenum films via a magnetron discharge  

Microsoft Academic Search

Argon is the process gas of choice for most magnetron sputtering applications due to its large atomic mass, inert chemistry, and relatively low cost. Other inert gases are available for use in sputtering deposition that have varying mass and hence different momentum behaviour during ion bombardment of solid surfaces — affecting sputter yield, particle implantation and incorporation of process gas

G. T. West; P. J. Kelly

61

Comments on ``Behaviour of inert gas bubbles under chemical concentration gradients'' by G.P. Tiwari  

NASA Astrophysics Data System (ADS)

The motion of inert gas bubbles induced by thermal vacancy gradients has previously been used by the present authors to understand gas bubble release in UO 2 and metals. This approach has been recently questioned by Tiwari. In the present letter, a critical discussion of his viewpoint is presented, together with an analysis of the important experimental results of Marachov et al. There appears to be good evidence for the disputed effect.

Evans, J. H.; van Veen, A.

1998-01-01

62

Effectiveness of Various Concentrations of an Inert Gas Mixture for Preventing and Suppressing Mining Equipment Cab Fires: Development of a Dual Cab Fire Inerting System.  

National Technical Information Service (NTIS)

The National Institute for Occupational Safety and Health (NIOSH/PRL) conducted a series of large-scale experiments to evaluate the effectiveness and safety of various concentrations of an inert gas mixture (CO2, 8%; N2, 50%; Ar, 42%) for preventing and s...

C. D. Litton M. I. De Rosa

2008-01-01

63

Effect of High-Pressure Inert Gas Annealing on AlON/Ge Gate Stacks  

NASA Astrophysics Data System (ADS)

We investigated germanium (Ge) metal--insulator--semiconductor (MIS) gate stacks with aluminum oxynitride (AlON) thin dielectric film. We found that high-pressure inert gas post deposition annealing (PDA) using N2 or Ar gas dramatically improved the electrical properties of AlON/Ge MIS gate stacks. The advantage of this process over high-pressure O2 oxidation or annealing, which produce excellent Ge gate stacks, is that no further interface layer growth in the N2 or Ar PDA is expected. We expect that thin AlON films combined with high-pressure inert gas PDA will provide a new way to achieve excellent Ge-MIS gate stacks with scalable equivalent oxide thickness.

Tabata, Toshiyuki; Nagashio, Kosuke; Toriumi, Akira

2012-09-01

64

Heat Transfer and Pressure Drop in Concentric Annular Flows of Binary Inert Gas Mixtures  

NASA Technical Reports Server (NTRS)

Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 < r* < 0.83. These smooth tube data may serve as a reference to the heat transfer and pressure drop performance in annuli, tubes, and channels having helixes or spacer ribs, or other surfaces.

Reid, R. S.; Martin, J. J.; Yocum, D. J.; Stewart, E. T.

2007-01-01

65

Onboard Inert Gas Generation System/Onboard Oxygen Gas Generation System (OBIGGS/OBOGS) Study. Part 1; Aircraft System Requirements  

NASA Technical Reports Server (NTRS)

The purpose of this technology assessment is to define a multiphase research study program investigating Onboard Inert Gas Generation Systems (OBIGGS) and Onboard Oxygen Generation Systems (OBOGS) that would identify current airplane systems design and certification requirements (Subtask 1); explore state-of-the-art technology (Subtask 2); develop systems specifications (Subtask 3); and develop an initial system design (Subtask 4). If feasible, consideration may be given to the development of a prototype laboratory test system that could potentially be used in commercial transport aircraft (Subtask 5). These systems should be capable of providing inert nitrogen gas for improved fire cargo compartment fire suppression and fuel tank inerting and emergency oxygen for crew and passenger use. Subtask I of this research study, presented herein, defines current production aircraft certification requirements and design objectives necessary to meet mandatory FAA certification requirements and Boeing design and performance specifications. These requirements will be utilized for baseline comparisons for subsequent OBIGGS/OBOGS application evaluations and assessments.

Reynolds, Thomas L.; Bailey, Delbert B.; Lewinski, Daniel F.; Roseburg, Conrad M.; Palaszewski, Bryan (Technical Monitor)

2001-01-01

66

Research on inert gas narcosis and air velocity effects on metabolic performance  

NASA Technical Reports Server (NTRS)

The effects of air velocity on metabolic performance are studied by using high forced airflow in a closed environment as a mechanism to control the concentration of volatile animal wastes. Air velocities between 100 and 200 ft/min are without significant effects on the metabolism of rats. At velocities of 200 ft/min and above, oxygen consumption and CO2 production as well as food consumption increase. In most instances, the changes are on the order of 5-10%. At the same time, the RQ for the animals increases slightly and generally correlates well with oxygen consumption and CO2 production. Experiments on the nature of inert gas narcosis show that halothane and methoxyflurane are rather potent inhibitors of the NADH:O2 oxidoreductase system in rats. These experiments suggest that the mechanism of inert gas narcosis is not mandatorily related to a membrane surface phenomenon.

1974-01-01

67

Changing inert gas mixing ratios on Mars using the York Mars GCM  

NASA Astrophysics Data System (ADS)

The current version of the York Mars model, GEM-MARS, is currently undergoing revision, and is being re-developed and assessed to be used in a semi-operational mode for planetary missions. GEM-Mars is based on the dynamical core of the Canadian Weather Forecast GEM (Global Environment Multi-scale) Model and our current version of GEM-MARS uses version 3.3.0. (Experiments are continuing at BIRA with a version which has a staggered vertical grid.) This study intends to focus on the condensation aspects of CO2 and its impact on the mixing ratios of inert (on a seasonal time scale) species for example such as Ar, and CO. As CO2 floods the polar atmosphere in the springtime the mixing ratios of the inert species decrease until mixing from lower latitudes adjusts the balance. In winter time the opposite sequence is obtained. We use straightforward CO2 condensation based on the work of Forget (1998) and adjust the 4D mixing ratio of the species in the column to ensure mass conservation for the basic species which make up the Martian atmosphere.

Beagley, S. R.; Fomichev, V. I.; Semeniuk, K.; Kaminski, J. W.; Wu, D.; Lupu, A.; Fazel-Rastgar, F.; McConnell, J. C.; Daerden, F.; Neary, L.

2012-12-01

68

Optimization of pyrolysis conditions of scrap tires under inert gas atmosphere  

Microsoft Academic Search

A pyrolysis system was designed for the production of activated carbon and other products from scrap tires. The system allows work under inert atmosphere (N2 gas). The pyrolysis experiments were carried out in a fixed-bed batch reactor of (1.25m length and 0.03m o.d.) which was heated by an electric furnace. The feed material used was scrap tires supplied from General

Mahmood M. Barbooti; Thamer J. Mohamed; Alaa A. Hussain; Falak O. Abas

2004-01-01

69

X-ray characterization of inert gas atomized low carbon astroloy powder  

Microsoft Academic Search

X-ray studies were carried out on an inert gas atomized low carbon (LC) astroloy powder. The as-atomized powder was sieved into different fractions of narrow size using suitable combination of sieves to study the effect of particle size on the compositional homogeneity and lattice parameter. Using a slow scanning X-ray diffraction technique, the lattice parameter of the sample and broadening

Mahendra Kumar; S. V. Nagender Naidu

2004-01-01

70

Microstructure and magnetic properties of inert gas atomized rare earth permanent magnetic materials  

Microsoft Academic Search

Several permanent magnet alloys based on the ternary NdāFeāāB (2-14-1) composition have been prepared by inert gas atomization (IGA). The microstructure and magnetic properties of these alloys have been studied as a function of particle size, both before and after heat treatment. Different particle sizes have characteristic properties due to the differences in cooling rate experienced during solidification from the

C. H. Sellers; T. A. Hyde; D. J. Branagan; L. H. Lewis; V. Panchanathan

1997-01-01

71

Microstructure and magnetic properties of inert gas atomized rare earth permanent magnetic materials  

Microsoft Academic Search

Several permanent magnet alloys based on the ternary Nd2Fe14B (2-14-1) composition have been prepared by inert gas atomization (IGA). The microstructure and magnetic properties of these alloys have been studied as a function of particle size, both before and after heat treatment. Different particle sizes have characteristic properties due to the differences in cooling rate experienced during solidification from the

C. H. Sellers; T. A. Hyde; D. J. Branagan; L. H. Lewis; V. Panchanathan

1997-01-01

72

BRIEF COMMUNICATIONS: Experimental investigation of a gasdynamic laser utilizing mixtures of carbon monoxide and an inert gas  

Microsoft Academic Search

Stimulated emission was obtained from mixtures of CO molecules with inert gases (He, Ne, Ar, Kr) expanding supersonically in a planar nozzle 4 cm long (the expansion ratio at the edge of the nozzle was 100). The influence of the nature of the inert gas and of the initial pressure of the mixture on the output power of the stimulated

V. F. Gavrikov; A. P. Dronov; V. K. Orlov; A. K. Piskunov

1975-01-01

73

TIG WELDER LOCATED IN THE CLEAN ROOM OF THE TECHNICAL SERVICES BUILDING TSB - THE INERT GAS WELDING  

NASA Technical Reports Server (NTRS)

TIG WELDER LOCATED IN THE CLEAN ROOM OF THE TECHNICAL SERVICES BUILDING TSB - THE INERT GAS WELDING FACILITY IS USED FOR WELDING REFRACTORY METALS IN CONNECTION WITH THE COLUMBIUM LIQUID SODIUM LOOP PROJECT

1963-01-01

74

A Model for Surface Induced Growth of Inert Gas Bubbles in Irradiated Copper-Boron Alloys  

SciTech Connect

A matrix containing inert gas bubbles dilates in direct proportion to the growth experienced by the gas bubbles. This phenomenon is termed as swelling. A model for the swelling induced by the growth of the helium gas bubbles in irradiated copper-boron alloys is presented. The bubbles grow by acquiring vacancies from the external surface, which acts as a source of vacancies. The vacancies reach the surface of the bubbles mainly via lattice diffusion and to a limited extent via diffusion through short-circuiting paths such as grain boundaries and dislocation pipes. The model predicts that overall swelling of the matrix varies as 1.5 power of time. Another consequence of the present model is that the growth rate of a gas bubble varies inversely as the cube of its distance from the external surface. The model has been applied to the data on irradiated copper-boron alloys and found to be in accord with the experimental results. The model is general and can be applied to the growth of all kinds of stationary inert gas bubbles trapped within a crystalline matrix. (authors)

Tiwari, G.P.; Ramadasan, E. [Post Irradiation Examination Division, Bhabha Atomic Research Division (India)

2006-07-01

75

Quantum gas-liquid condensation in an attractive Bose gas  

SciTech Connect

Gas-liquid condensation (GLC) in an attractive Bose gas is studied on the basis of statistical mechanics. Using some results in combinatorial mathematics, the following are derived. (1) With decreasing temperature, the Bose-statistical coherence grows in the many-body wave function, which gives rise to the divergence of the grand partition function prior to Bose-Einstein condensation. It is a quantum-mechanical analogue to the GLC in a classical gas (quantum GLC). (2) This GLC is triggered by the bosons with zero momentum. Compared with the classical GLC, an incomparably weaker attractive force creates it. For the system showing the quantum GLC, we discuss a cold helium 4 gas at sufficiently low pressure.

Koh, Shun-ichiro [Physics Division, Faculty of Education, Kochi University, Akebono-cho, 2-5-1, Kochi 780 (Japan)

2005-07-01

76

Gas Condensation in the Galactic Halo  

NASA Astrophysics Data System (ADS)

Using adaptive mesh refinement (AMR) hydrodynamic simulations of vertically stratified hot halo gas, we examine the conditions under which clouds can form and condense out of the hot halo medium to potentially fuel star formation in the gaseous disk. We find that halo clouds do not develop from linear isobaric perturbations. This is a regime where the cooling time is longer than the Brunt-Väisälä time, confirming previous linear analysis. We extend the analysis into the nonlinear regime by considering mildly or strongly nonlinear perturbations with overdensities up to 100, also varying the initial height, the cloud size, and the metallicity of the gas. Here, the result depends on the ratio of cooling time to the time required to accelerate the cloud to the sound speed (similar to the dynamical time). If the ratio exceeds a critical value near unity, the cloud is accelerated without further cooling and gets disrupted by Kelvin-Helmholtz and/or Rayleigh-Taylor instabilities. If it is less than the critical value, the cloud cools and condenses before disruption. Accreting gas with overdensities of 10-20 is expected to be marginally unstable; the cooling fraction will depend on the metallicity, the size of the incoming cloud, and the distance to the galaxy. Locally enhanced overdensities within cold streams have a higher likelihood of cooling out. Our results have implications on the evolution of clouds seeded by cold accretion that are barely resolved in current cosmological hydrodynamic simulations and absorption line systems detected in galaxy halos.

Joung, M. Ryan; Bryan, Greg L.; Putman, Mary E.

2012-02-01

77

GAS CONDENSATION IN THE GALACTIC HALO  

SciTech Connect

Using adaptive mesh refinement (AMR) hydrodynamic simulations of vertically stratified hot halo gas, we examine the conditions under which clouds can form and condense out of the hot halo medium to potentially fuel star formation in the gaseous disk. We find that halo clouds do not develop from linear isobaric perturbations. This is a regime where the cooling time is longer than the Brunt-Vaeisaelae time, confirming previous linear analysis. We extend the analysis into the nonlinear regime by considering mildly or strongly nonlinear perturbations with overdensities up to 100, also varying the initial height, the cloud size, and the metallicity of the gas. Here, the result depends on the ratio of cooling time to the time required to accelerate the cloud to the sound speed (similar to the dynamical time). If the ratio exceeds a critical value near unity, the cloud is accelerated without further cooling and gets disrupted by Kelvin-Helmholtz and/or Rayleigh-Taylor instabilities. If it is less than the critical value, the cloud cools and condenses before disruption. Accreting gas with overdensities of 10-20 is expected to be marginally unstable; the cooling fraction will depend on the metallicity, the size of the incoming cloud, and the distance to the galaxy. Locally enhanced overdensities within cold streams have a higher likelihood of cooling out. Our results have implications on the evolution of clouds seeded by cold accretion that are barely resolved in current cosmological hydrodynamic simulations and absorption line systems detected in galaxy halos.

Joung, M. Ryan; Bryan, Greg L.; Putman, Mary E., E-mail: moo@astro.columbia.edu [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States)

2012-02-01

78

Validation of myocardial blood flow estimation with nitrogen-13 ammonia PET by the argon inert gas technique in humans  

Microsoft Academic Search

We simultaneously determined global myocardial blood flow (MBF) by the argon inert gas technique and by nitrogen-13 ammonia positron emission tomography (PET) to validate PET-derived MBF values in humans. A total of 19 patients were investigated at rest (n=19) and during adenosine-induced hyperaemia (n=16). Regional coronary artery stenoses were ruled out by angiography. The argon inert gas method uses the

Jörg Kotzerke; Gerhard Glatting; Jörg van den Hoff; Martin Höher; Bernd Neumaier; Jochen Wöhrle; Sven N. Reske

2001-01-01

79

Resonant gas oscillation with evaporation and condensation  

NASA Astrophysics Data System (ADS)

Resonant gas oscillation in a closed tube bounded by an oscillating plate and a vaporliquid interface is theoretically analyzed by applying the asymptotic theory to the ES-BGK Boltzmann equation for the case of M2~=Kn<<1 and a small evaporation coefficient ? = O(Kn), where M and Kn are the typical Mach number and the Knudsen number, respectively. As a result, we derive a nonlinear integro-differential equation for determining the wave profile with the evaporation and condensation in the form including ?.

Inaba, Masashi; Yano, Takeru; Watanabe, Masao; Kobayashi, Kazumichi; Fujikawa, Shigeo

2012-09-01

80

Modelling the transient behaviour of pulsed current tungsten-inert-gas weldpools  

NASA Astrophysics Data System (ADS)

A three-dimensional model is established to simulate the pulsed current tungsten-inert-gas (TIG) welding process. The goal is to analyse the cyclic variation of fluid flow and heat transfer in weldpools under periodic arc heat input. To this end, an algorithm, which is capable of handling the transience, nonlinearity, multiphase and strong coupling encountered in this work, is developed. The numerical simulations demonstrate the transient behaviour of weldpools under pulsed current. Experimental data are compared with numerical results to show the effectiveness of the developed model.

Wu, C. S.; Zheng, W.; Wu, L.

1999-01-01

81

Polishing of Optical Media by Dielectric Barrier Discharge Inert Gas Plasma at Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

In this paper, surface smoothing of optical glasses, glass ceramic and sapphire using a low-power dielectric barrier discharge inert gas plasma at atmospheric pressure is presented. For this low temperature treatment method, no vacuum devices or chemicals are required. It is shown that by such plasma treatment the micro roughness and waviness of the investigated polished surfaces were significantly decreased, resulting in a decrease in surface scattering. Further, plasma polishing of lapped fused silica is introduced. Based on simulation results, a plasma physical process is suggested to be the underlying mechanism for initialising the observed smoothing effect.

Gerhard, C.; Weihs, T.; Luca, A.; Wieneke, S.; Viöl, W.

2013-12-01

82

Correlations predict gas-condensate flow through chokes  

Microsoft Academic Search

Empirical correlations have developed to describe the behavior of gas-condensate flow through surface chokes. The field data were obtained from a Middle East gas-condensate reservoir and cover a wide range of flow rates and choke sizes. Correlations for gas-condensate systems have not been previously available. These new correlations will help the production engineer to size chokes for controlling production of

M. E. Osman; M. E. Dokla

1992-01-01

83

The Diffusion of Oxygen, Carbon Dioxide, and Inert Gas in Flowing Blood  

PubMed Central

Measurements were made of exchange rates of oxygen, carbon dioxide, and krypton-85 with blood at 37.5°C. Gas transfer took place across a 1 mil silicone rubber membrane. The blood was in a rotating disk boundary layer flow, and the controlling resistance to transfer was the concentration boundary layer. Measured rates were compared with rates predicted from the equation of convective diffusion using velocities derived from the Navier-Stokes equations and diffusivities calculated from the theory for conduction in a heterogeneous medium. The measured absorption rate of krypton-85 was closely predicted by this model. Significant deposition of material onto the membrane surface, resulting in an increased transfer resistance, occurred in one experiment with blood previously used in a nonmembrane type artificial lung. The desorption rate of oxygen from blood at low Po21 was up to four times the corresponding transfer rate of inert gas. This effect is described somewhat conservatively by a local equilibrium form of the convective diffusion equation. The carbon dioxide transfer rate in blood near venous conditions was about twice that of inert gas, a rate significantly greater than predicted by the local equilibrium theory. It should be possible to apply these theoretical methods to predict exchange rates with blood flowing in systems of other geometries.

Spaeth, E. E.; Friedlander, S. K.

1967-01-01

84

Development of a Market Optimized Condensing Gas Water Heater  

Microsoft Academic Search

This program covered the development of a market optimized condensing gas water heater for residential applications. The intent of the program was to develop a condensing design that minimized the large initial cost premium associated with traditional condensing water heater designs. Equally important was that the considered approach utilizes design and construction methods that deliver the desired efficiency without compromising

Peter Pescatore

2006-01-01

85

Spark gap switch system with condensable dielectric gas  

DOEpatents

A spark gap switch system is disclosed which is capable of operating at a high pulse rate comprising an insulated switch housing having a purging gas entrance port and a gas exit port, a pair of spaced apart electrodes each having one end thereof within the housing and defining a spark gap therebetween, an easily condensable and preferably low molecular weight insulating gas flowing through the switch housing from the housing, a heat exchanger/condenser for condensing the insulating gas after it exits from the housing, a pump for recirculating the condensed insulating gas as a liquid back to the housing, and a heater exchanger/evaporator to vaporize at least a portion of the condensed insulating gas back into a vapor prior to flowing the insulating gas back into the housing.

Thayer, III, William J. (Kent, WA)

1991-01-01

86

Quantitative analysis of trace bulk oxygen in silicon wafers using an inert gas fusion method.  

PubMed

This paper describes a method for removing oxide film from the surface of silicon wafers using an inert gas fusion impulse furnace and precise determination of bulk oxygen within the wafer. A silicon wafer was cut to about 0.35 g (6 x 13 x 2 mm) and dropped into a graphite crucible. The sample was then heated for 40 s at 1300 degrees C. The wafer's oxide film was reduced by carbon and removed as carbon monoxide. The treated silicon sample was taken out of the graphite crucible and maintained again with the holder of the oxygen analyzer. The graphite crucible was then heated to 2100 degrees C. The treated silicon sample was dropped into the heated graphite crucible and the trace bulk oxygen in the wafer was measured using the inert gas fusion infrared absorption method. The relative standard deviations of the oxygen in silicon wafer samples with the removed surface oxide film were determined to be 0.8% for 9.8 x 10(17) atoms/cm3, and 2.7% for 13.0 x 10(17) atoms/cm3. PMID:14640456

Uchihara, Hiroshi; Ikeda, Masahiko; Nakahara, Taketoshi

2003-11-01

87

Experimental observations of effects of inert gas on cavity formation during irradiation  

SciTech Connect

Cavity (void) formation and swelling in non-fissile materials during neutron irradiation and charged particle bombardments are reviewed. Helium is the most important inert gas and is primarily active as a cavity nucleant. It also enhances formation of dislocation structure. Preimplantation of helium overstimulates cavity nucleation and gives a different temperature response of swelling than when helium is coimplanted during the damage process. Helium affects, and is affected by, radiation-induced phase instability. Many of these effects are explainable in terms of cavity nucleation on submicroscopic critical size gas bubbles, and on the influence of the neutral sink strength of such bubbles. Titanium and zirconium resist cavity formation when vacancy loops are present.

Farrell, K.

1980-04-01

88

CFD simulation of water vapour condensation in the presence of non-condensable gas in vertical cylindrical condensers  

PubMed Central

This paper presents the simulation of the condensation of water vapour in the presence of non-condensable gas using computational fluid dynamics (CFD) for turbulent flows in a vertical cylindrical condenser tube. The simulation accounts for the turbulent flow of the gas mixture, the condenser wall and the turbulent flow of the coolant in the annular channel with no assumptions of constant wall temperature or heat flux. The condensate film is assumed to occupy a negligible volume and its effect on the condensation of the water vapour has been taken into account by imposing a set of boundary conditions. A new strategy is used to overcome the limitation of the currently available commercial CFD package to solve the simultaneous simulation of flows involving multispecies and fluids of gas and liquid in separate channels. The results from the CFD simulations are compared with the experimental results from the literature for the condensation of water vapour with air as the non-condensable gas and for inlet mass fraction of the water vapour from 0.66 to 0.98. The CFD simulation results in general agree well with the directly measured quantities and it is found that the variation of heat flux in the condenser tube is more complex than a simple polynomial curve fit. The CFD results also show that, at least for flows involving high water vapour content, the axial velocity of the gas mixture at the interface between the gas mixture and the condensate film is in general not small and cannot be neglected.

Li, Jun-De

2013-01-01

89

Experimental study on steam condensation with non-condensable gas in horizontal microchannels  

NASA Astrophysics Data System (ADS)

This paper experimentally studied steam condensation with non-condensable gas in trapezoidal microchannels. The effect of noncondensable gas on condensation two-phase flow patterns and the characteristics of heat transfer and frictional pressure drop were investigated. The visualization study results showed that the special intermittent annular flow was found in the microchannel under the condition of larger mole fraction of noncondensable gas and lower steam mass flux; the apical area of injection was much larger and the neck of injection was longer for mixture gas with lower mole fraction of noncondensable gas in comparison with pure steam condensation; meanwhile, the noncondensable gas resulted in the decrease of flow patterns transitional steam mass flux and quality. The experimental results also indicated that the frictional pressure drop increased with the increasing mole fraction of noncondensable gas when the steam mass flux was fixed. Unlike nature convective condensation heat transfer, the mole fraction of noncondensable gas had little effect on Nusselt number. Based on experimental data, the predictive correlation of Nusselt number for mixture gas condensation in microchannels was established showed good agreement with experimental data.

Ma, Xuehu; Fan, Xiaoguang; Lan, Zhong; Jiang, Rui; Tao, Bai

2013-07-01

90

Measuring Diffusivity in Supercooled Liquid Nanoscale Films using Inert Gas Permeation: I. Kinetic Model and Scaling Methods  

SciTech Connect

We describe in detail a diffusion model used to simulate inert gas transport through supercooled liquid overlayers. In recent work, the transport of the inert gas has been shown to be an effective probe of the diffusivity of supercooled liquid methanol in the experimentally challenging regime near the glass transition temperature. The model simulations accurately and quantitatively describe the inert gas permeation desorption spectra. The simulation results are used to validate universal scaling relationships between the diffusivity, overlayer thickness, and the temperature ramp rate for isothermal and temperature programmed desorption. From these scaling relationships we derive simple equations from which the diffusivity can be obtained using the peak desorption time or temperature for an isothermal or set of TPD experiments respectively without numerical simulation. The results presented here demonstrate that the permeation of gases through amorphous overlayers has the potential to be a powerful technique to obtain diffusivity data in deeply supercooled liquids.

Smith, R. Scott; Matthiesen, Jesper; Kay, Bruce D.

2010-11-07

91

Comparison of inert-gas-fusion and modified Kjeldahl techniques for determination of nitrogen in niobium alloys  

NASA Technical Reports Server (NTRS)

This report compares results obtained for the determination of nitrogen in a selected group of niobium-base alloys by the inert-gas-fusion and the Kjeldahl procedures. In the inert-gas-fusion procedure the sample is heated to approximately 2700 C in a helium atmosphere in a single-use graphite crucible. A platinum flux is used to facilitate melting of the sample. The Kjeldahl method consisted of a rapid decomposition with a mixture of hydrofluoric acid, phosphoric acid, and potassium chromate; distillation in the presence of sodium hydroxide; and highly sensitive spectrophotometry with nitroprusside-catalyzed indophenol. In the 30- to 80-ppm range, the relative standard deviation was 5 to 7 percent for the inert-gas-fusion procedure and 2 to 8 percent for the Kjeldahl procedure. The agreement of the nitrogen results obtained by the two techniques is considered satisfactory.

Merkle, E. J.; Graab, J. W.; Davis, W. F.

1974-01-01

92

Gap states in pentacene thin film induced by inert gas exposure.  

PubMed

We studied gas-exposure effects on pentacene (Pn) films on SiO2 and Au(111) substrates by ultrahigh sensitivity photoelectron spectroscopy, which can detect the density of states of ?10(16) states eV-1?cm-3 comparable to electrical measurements. The results show the striking effects for Pn/SiO2: exposure to inert gas (N2 and Ar) produces a sharp rise in gap states from ?10(16) to ?10(18) states eV-1?cm-3 and pushes the Fermi level closer to the valence band (0.15-0.17 eV), as does exposure to O2 (0.20 eV), while no such gas-exposure effect is observed for Pn/Au(111). The results demonstrate that these gap states originate from small imperfections in the Pn packing structure, which are induced by gas penetration into the film through the crystal grain boundaries. PMID:23848923

Bussolotti, Fabio; Kera, Satoshi; Kudo, Kazuhiro; Kahn, Antoine; Ueno, Nobuo

2013-06-28

93

Electron temperature and density measurement of tungsten inert gas arcs with Ar-He shielding gas mixture  

NASA Astrophysics Data System (ADS)

The diagnostics of atmospheric welding plasma is a well-established technology. In most cases the measurements are limited to processes using pure shielding gas. However in many applications shielding gas is a mixture of various components including metal vapor in gas metal arc welding (GMAW). Shielding gas mixtures are intentionally used for tungsten inert gas (TIG) welding in order to improve the welding performance. For example adding Helium to Argon shielding gas allows the weld geometry and porosity to be influenced. Yet thermal plasmas produced with gas mixtures or metal vapor still require further experimental investigation. In this work coherent Thomson scattering is used to measure electron temperature and density in these plasmas, since this technique allows independent measurements of electron and ion temperature. Here thermal plasmas generated by a TIG process with 50% Argon and 50% Helium shielding gas mixture have been investigated. Electron temperature and density measured by coherent Thomson scattering have been compared to the results of spectroscopic measurements of the plasma density using Stark broadening of the 696.5 nm Argon spectral line. Further investigations of MIG processes using Thomson scattering technique are planned.

Kühn-Kauffeldt, M.; Marques, J.-L.; Forster, G.; Schein, J.

2013-10-01

94

Fusao a arco sob atmosfera de gas inerte da esponja de zirconio. (Arc melting in inert gas atmosphere of zirconium sponge).  

National Technical Information Service (NTIS)

The obtainment of metallic zirconium in laboratory scale with commercial and nuclear quality is the objective of the Metallurgy Department of IEN/CNEN - Brazil, so a melting procedure of zirconium sponge in laboratory scale using an arc furnace in inert a...

O. Julio Junior A. H. P. Andrade

1991-01-01

95

Equilibrium revaporization of retrograde condensate by dry gas injection  

Microsoft Academic Search

This paper presents the results of laboratory flow experiments concerning the revaporization recovery of retrograde condensate by dry gas injection. The purposes of the work were to demonstrate that the flowing fluid is vapor in equilibrium with the condensate, to investigate the effect of wettability on the revaporization of retrograde liquid, and to provide an indication of the amount of

L. R. Smith; L. Yarborough

1967-01-01

96

Condensate production optimization in the Arun gas field  

SciTech Connect

In the Arum Field, Mobil Oil Indonesia Inc. (MOI) has implemented a condensate production optimization program on its Supervisory Control and Data Acquisition (SCADA) system. This program has been proven successful in improving stabilized condensate production by up to 3% or 3200 BPD at 2,270 MMSCF daily average separator gas flowrate. It is detailed in this paper.

Risan, R.M.; Abdullah, S.; Hidayat, Z. (Mobil Oil Indonesia (ID))

1988-01-01

97

Noninvasive Determination of Cardiac Output by the Inert-Gas-Rebreathing Method – Comparison with Cardiovascular Magnetic Resonance Imaging  

Microsoft Academic Search

Background: An easy, noninvasive and accurate technique for measuring cardiac output (CO) would be desirable for the diagnosis and therapy of cardiac diseases. Innocor, a novel inert-gas-rebreathing (IGR) system, has shown promising results in smaller studies. An extensive evaluation in a larger, less homogeneous patient collective is lacking. Methods: We prospectively assessed the accuracy and reproducibility of CO measurements obtained

Joachim Saur; Stephan Fluechter; Frederik Trinkmann; Theano Papavassiliu; Stefan Schoenberg; Joerg Weissmann; Dariusch Haghi; Martin Borggrefe; Jens J. Kaden

2009-01-01

98

Non-Invasive Measurement of Cardiac Output during Atrial Fibrillation: Comparison between Cardiac Magnetic Resonance Imaging and Inert Gas Rebreathing  

Microsoft Academic Search

Objectives: Atrial fibrillation (AF) is one of the most frequent heart rhythm disorders. It potentially influences cardiac function and its measurement. Cardiac magnetic resonance imaging (CMR) has become the new gold standard for non-invasive assessment of cardiac output (CO). A novel inert gas rebreathing (IGR) device based on the Fick Principle also proved promising in patients in sinus rhythm (SR).

J. Saur; F. Trinkmann; C. Doesch; J. Weissmann; K. Hamm; S. O. Schoenberg; M. Borggrefe; D. Haghi; J. J. Kaden

2010-01-01

99

Non-invasive assessment of pulmonary blood flow using an inert gas rebreathing device in fibrotic lung disease  

Microsoft Academic Search

Background and aimsPulmonary hypertension (PH) is increasingly recognised in patients with diffuse lung disease, and is associated with increased mortality. Cardiac output (CO) is a prognostic marker in PH. Non-invasive assessment of pulmonary blood flow (PBFINNOCOR) with the inert gas rebreathing Innocor device has been validated against CO in PH, but not in PH associated with parenchymal lung disease. PBFINNOCOR

Tamera J Corte; Athol U Wells; Michael A Gatzoulis; Derek Cramer; Simon Ward; Peter S Macdonald; Konstantinos Dimopoulos; Stephen J Wort

2010-01-01

100

Requirements for long-life operation of inert gas hollow cathodes - Preliminary results  

NASA Technical Reports Server (NTRS)

An experimental investigation was initiated to establish conditioning procedures for reliable hollow cathode operation via the characterization of critical parameters in a representative cathode test facility. From vacuum pumpdown rates, it was found that approximately 1.5 hours were required to achieve pressure levels within 5 percent of the lowest attainable pressure for this facility, depending on the purge conditions. The facility atmosphere was determined by a residual gas analyzer to be composed of primarily air and water vapor. The effects of vacuum pumping and inert gas purging were evaluated. A maximum effective leakage rate of 2.0 x 10 (exp -3) sccm was observed and its probable causes were examined. An extended test of a 0.64 cm diameter Mo-Re hollow cathode was successfully completed. This test ran for 504 hours at an emission current of 23.0 amperes and a xenon flow rate of 6.1 sccm. Discharge voltage rose continuously from 15 to 21 volts over the course of the test. The temperature of the cathode body during the test was relatively stable at 1160 C. Post-test examination revealed ion-bombardment texturing of the orifice plate to be the only detectable sign of wear on the hollow cathode.

Verhey, Timothy R.; Macrae, Gregory S.

1990-01-01

101

Requirements for long-life operation of inert gas hollow cathodes: Preliminary report  

NASA Technical Reports Server (NTRS)

An experimental investigation was initiated to establish conditioning procedures for reliable hollow cathode operation via the characterization of critical parameters in a representative cathode test facility. From vacuum pumpdown rates, it was found that approximately 1.5 hours were required to achieve pressure levels within 5 percent of the lowest attainable pressure for this facility, depending on the purge conditions. The facility atmosphere was determined by a residual gas analyzer to be composed of primarily air and water vapor. The effects of vacuum pumping and inert gas purging were evaluated. A maximum effective leakage rate of 2.0 x 10(exp -3)sccm was observed and its probable causes were examined. An extended test of a 0.64 cm diameter Mo-Re hollow cathode was successfully completed. This test ran for 504 hours at an emission current of 23.0 amperes and a xenon flow rate of 6.1 sccm. Discharge voltage rose continuously from 15 to 21 volts over the course of the test. The temperature of the cathode body during the test was relatively stable at 1160 C. Post-test examination revealed ion-bombardment texturing of the orifice plate to be the only detectable sign of wear on the hollow cathode.

Verhey, Timothy R.; Macrae, Gregory S.

1990-01-01

102

Condensate fluctuations in the dilute Bose gas  

SciTech Connect

The fluctuations of a number of particles in the Bose-Einstein condensate are studied in the grand canonical ensemble with an effective single-mode Hamiltonian, which is derived from an assumption that the mode corresponding to the Bose-Einstein condensate does not asymptotically correlate with other modes. The fluctuations are evaluated in the dilute limit with a proposed simple method, which is beyond the mean-field approximation. The accuracy of the latter is estimated; it is shown that the mean-field scheme does not work for the single-mode Hamiltonian, while for the Hartree Hamiltonian it allows us to estimate the condensate fluctuations up to a numerical factor. As a hypothesis, a formula is proposed that relates the fluctuations in the canonical ensemble with that of the grand canonical one.

Cherny, Alexander Yu. [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Strasse 38, D-01187 Dresden (Germany); and Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980, Dubna (Russian Federation)

2005-04-01

103

Formation of inorganic electride thin films via site-selective extrusion by energetic inert gas ions  

NASA Astrophysics Data System (ADS)

Inert gas ion implantation (acceleration voltage 300 kV) into polycrystalline 12CaO.7Al2O3 (C12A7) films was investigated with fluences from 1×1016 to 1×1017 cm-2 at elevated temperatures. Upon hot implantation at 600 °C with fluences greater than 1×1017 cm-2, the obtained films were colored and exhibited high electrical conductivity in the as-implanted state. The extrusion of O2- ions encaged in the crystallographic cages of C12A7 crystal, which leaves electrons in the cages at concentrations up to ~1.4×1021 cm-3, may cause the high electrical conductivity. On the other hand, when the fluence is less than 1×1017 cm-2, the as-implanted films are optically transparent and electrically insulating. The conductivity is enhanced and the films become colored by irradiating with ultraviolet light due to the formation of F+-like centers. The electrons forming the F+-like centers are photo released from the encaged H- ions, which are presumably derived from the preexisting OH- groups. The induced electron concentration is proportional to the calculated displacements per atom, which suggests that nuclear collision effects of the implanted ions play a dominant role in forming the electron and H- ion in the films. The hot ion implantation technique provides a nonchemical process for preparing electronic conductive C12A7 films.

Miyakawa, Masashi; Toda, Yoshitake; Hayashi, Katsuro; Hirano, Masahiro; Kamiya, Toshio; Matsunami, Noriaki; Hosono, Hideo

2005-01-01

104

Energy balance in disk and CO2 laser beam inert gas fusion cutting  

NASA Astrophysics Data System (ADS)

Experimental, numerical and analytical investigations were performed to give a possible explanation of the differences in cutting quality detected for inert gas laser beam cutting process performed with disk and CO2 laser sources. Cutting experiments were carried out at maximum cutting speed on cold work steel test specimens with different sheet thicknesses. The particular feature of the applied experimental setup was the similar geometry of both the CO2 and the disk laser beam with comparable values of the focus diameter and the Rayleigh length. The thermodynamic analysis was based on experimentally primary losses evaluation by means of polymethylmethacrylate (PMMA) blocks, on numerical computation of conductive power losses and analytical calculation of the remaining terms of energy balance. Energy balance allowed the evaluation of secondary losses and proportion of vaporized kerf volume used for justifying the lower quality of disk laser cuts. The lower proportion of vaporized kerf volume detected for disk laser cuts results in an increased process temperature, thus an increase of viscosity of molten material and the subsequent more difficult ejection of the melted material from the cut kerf.

Scintilla, Leonardo Daniele; Tricarico, Luigi; Wetzig, Andreas; Beyer, Eckhard

2012-02-01

105

Effect of inert cover gas on performance of radioisotope Stirling space power system  

NASA Astrophysics Data System (ADS)

This paper describes an updated Orbital design of a radioisotope Stirling power system and its predicted performance at the beginning and end of a six-year mission to the Jovian moon Europa. The design is based on General Purpose Heat Source (GPHS) modules identical to those previously developed and safety-qualified by the Department of Energy (DOE) which were successfully launched on missions to Jupiter and Saturn by the Jet Propulsion Laboratory (JPL). In each generator, the heat produced by the decay of the Pu-238 isotope is converted to electric power by two free-piston Stirling engines and linear alternators developed by Stirling Technology Company (STC), and their rejected waste heat is transported to radiators by heat pipes. The principal difference between the proposed system design and previous Orbital designs (Or et al., 2000) is the thermal insulation between the heat source and the generator's housing. Previous designs had employed multifoil insulation, whereas the design described here employs Min-K-1800 thermal insulation. Such insulation had been successfully used by Teledyne and GE in earlier RTGs (Radioisotope Thermoelectric Generators). Although Min-K is a much poorer insulator than multifoil in vacuum and requires a substantially greater thickness for equivalent performance, it offers compensating advantages. Specifically it makes it possible to adjust the generator's BOM temperatures by filling its interior volume with inert cover gas. This makes it possible to meet the generator's BOM and EOM performance goals without exceeding its allowable temperature at the beginning of the mission. .

Carpenter, R.; Kumar, V.; Or, C.; Schock, A.

2001-02-01

106

Analysis of cracks in stainless steel TIG (tungsten inert gas) welds  

SciTech Connect

This report contains the results of a combined experimental and analytical study of ductile crack growth in tungsten inert gas (TIG) weldments of austenitic stainless steel specimens. The substantially greater yield strength of the weld metal relative to the base metal causes more plastic deformation in the base metal adjacent to the weld than in the weld metal. Accordingly, the analytical studies focused on the stress-strain interaction between the crack tip and the weld/base-metal interface. Experimental work involved tests using compact (tension) specimens of three different sizes and pipe bend experiments. The compact specimens were machined from a TIG weldment in Type 304 stainless steel plate. The pipe specimens were also TIG welded using the same welding procedures. Elastic-plastic finite element methods were used to model the experiments. In addition to the J-integral, different crack-tip integral parameters such as ..delta..T/sub p/* and J were evaluated. Also, engineering J-estimation methods were employed to predict the load-carrying capacity of the welded pipe with a circumferential through-wall crack under bending.

Nakagaki, M.; Marschall, C.; Brust, F.

1986-12-01

107

Thorium-232 exposure during tungsten inert gas arc welding and electrode sharpening.  

PubMed

To assess the exposure of welders to thorium-232 (232Th) during tungsten inert gas arc (TIG) welding, airborne concentrations of 232Th in the breathing zone of the welder and background levels were measured. The radioactive concentrations were 1.11 x 10(-2) Bq/m3 during TIG welding of aluminum (TIG/Al), 1.78 x 10(-4) Bq/m3 during TIG welding of stainless steel (TIG/SS), and 1.93 x 10(-1) Bq/m3 during electrode sharpening, with 5.82 x 10(-5) Bq/m3 background concentration. Although the annual intake of 232Th estimated using these values did not exceed the annual limit intake (ALI, 1.6 x 10(2) Bq), we recommend reducing 232Th exposure by substituting thoriated electrodes with a thorium-free electrodes, setting up local ventilation systems, and by using respiratory protective equipment. It is also necessary to inform workers that thoriated tungsten electrodes contain radioactive material. PMID:12916759

Saito, Hiroyuki; Hisanaga, Naomi; Okada, Yukiko; Hirai, Shoji; Arito, Heihachiro

2003-07-01

108

MOX and MOX with 237Np/241Am Inert Fission Gas Generation Comparison in ATR  

SciTech Connect

The treatment of spent fuel produced in nuclear power generation is one of the most important issues to both the nuclear community and the general public. One of the viable options to long-term geological disposal of spent fuel is to extract plutonium, minor actinides (MA), and potentially long-lived fission products from the spent fuel and transmute them into short-lived or stable radionuclides in currently operating light-water reactors (LWR), thus reducing the radiological toxicity of the nuclear waste stream. One of the challenges is to demonstrate that the burnup-dependent characteristic differences between Reactor-Grade Mixed Oxide (RG-MOX) fuel and RG-MOX fuel with MA Np-237 and Am 241 are minimal, particularly, the inert gas generation rate, such that the commercial MOX fuel experience base is applicable. Under the Advanced Fuel Cycle Initiative (AFCI), developmental fuel specimens in experimental assembly LWR-2 are being tested in the northwest (NW) I-24 irradiation position of the Advanced Test Reactor (ATR). The experiment uses MOX fuel test hardware, and contains capsules with MOX fuel consisting of mixed oxide manufactured fuel using reactor grade plutonium (RG-Pu) and mixed oxide manufactured fuel using RG-Pu with added Np/Am. This study will compare the fuel neutronics depletion characteristics of Case-1 RG-MOX and Case-2 RG-MOX with Np/Am.

G. S. Chang; M. Robel; W. J. Carmack; D. J. Utterbeck

2006-06-01

109

Joining titanium materials with tungsten inert gas welding, laser welding, and infrared brazing.  

PubMed

Titanium has a number of desirable properties for dental applications that include low density, excellent biocompatibility, and corrosion resistance. However, joining titanium is one of the practical problems with the use of titanium prostheses. Dissolved oxygen and hydrogen may cause severe embrittlement in titanium materials. Therefore the conventional dental soldering methods that use oxygen flame or air torch are not indicated for joining titanium materials. This study compared laser, tungsten inert gas, and infrared radiation heating methods for joining both pure titanium and Ti-6Al-4V alloy. Original rods that were not subjected to joining procedures were used as a control method. Mechanical tests and microstructure analysis were used to evaluate joined samples. Mechanical tests included Vickers microhardness and uniaxial tensile testing of the strength of the joints and percentage elongation. Two-way analysis of variance and Duncan's multiple range test were used to compare mean values of tensile strength and elongation for significant differences (p < or = 0.05). Tensile rupture occurred in the joint region of all specimens by cohesive failure. Ti-6Al-4V samples exhibited significantly greater tensile strength than pure titanium samples. Samples prepared by the three joining methods had markedly lower tensile elongation than the control titanium and Ti-6Al-4V rods. The changes in microstructure and microhardness were studied in the heat-affected and unaffected zones. Microhardness values increased in the heat-affected zone for all the specimens tested. PMID:8809260

Wang, R R; Welsch, G E

1995-11-01

110

Deliverability projection model for overpressured gas-condensate reservoirs  

SciTech Connect

During the depletion history of abnormally pressured reservoir, pressure is initially maintained by a decrease in the pore volume. The P/Z vs cumulative gas produced graph in such reservoirs shows two distinct slopes and the initial gas in place can be estimated by extrapolation of P/Z straight line after the reservoir gradient has been reduced to normal. This decrease in pore volume also results in a reduction in the effective permeability of the rock thus affecting the formation in-flow performance. In the gas-condensate reservoirs, hydrocarbon liquids drop out of the gas phase below the dewpoint pressures increasing the total liquids saturation. An increase in the liquid saturation decreases the relative permeability to gas. The paper develops a high pressure gas-condensate reservoir deliverability calculation incorporating the effect of gas permeability reduction due to a decrease in pore volume and increase in oil saturation.

Aziz, R.M.

1985-03-01

111

[Hydrogen and oxidative stress injury--from an inert gas to a medical gas].  

PubMed

Oxidative stress is intensive cellular oxidation caused by redundant reactive oxygen species (ROS) or free radicals. Redundant ROS causes DNA fracture, lipid peroxidation and protein inactivation, thus leading to severe cell damage. Recent studies have shown that hydrogen is a good anti-oxidant. It selectively reduces the hydroxyl radical, the most cytotoxic of ROS; however, it does not react with other ROS, which play physiological roles. As a result, it could protect tissues against oxidative stress injuries, such as ischemia/reperfusion injury of the heart, liver and intestine, cisplatin nephrotoxicity, sepsis and colon inflammation. As a medical gas, hydrogen may have a prospect for far-reaching clinical application. PMID:21503133

Zhang, Qiao-li; Du, Jun-bao; Tang, Chao-shu

2011-04-18

112

Casting particulate and fibrous metal-matrix composites by vacuum infiltration of a liquid metal under an inert gas pressure  

Microsoft Academic Search

A new method of making metal-matrix composites is reported. This method combines the essentials of three liquid-phase fabrication\\u000a methods: (i) vacuum infiltration, (ii) infiltration under an inert gas pressure, and (iii) squeeze casting. In this method,\\u000a the particulate or fibrous preform is placed in a mould and the matrix alloy is placed above the preform. The matrix alloy\\u000a is heated

Jingyu Yang; D. D. L. Chung

1989-01-01

113

Analysis of residual stress in metal-inert-gas-welded Al2024 using neutron and synchrotron X-ray diffraction  

Microsoft Academic Search

A combination of neutron and synchrotron X-ray diffraction was used to measure and map the full three-dimensional state of residual stress across the cross-section in coupon samples of metal-inert-gas (MIG)-welded 2024 aluminium alloy. Samples were analysed both as-welded and following a post-welding skim which served to remove the weld flash and reduce the plate thickness. The profile of the residual

S. Ganguly; V. Stelmukh; L. Edwards; M. E. Fitzpatrick

2008-01-01

114

A study of thorium exposure during tungsten inert gas welding in an airline engineering population.  

PubMed

To investigate the theoretic possibility of excessive exposure to thorium during the process of tungsten inert gas (TIG) welding using thoriated rods we carried out a cross-sectional study of TIG welders and an age- and skill-matched group. We measured the radiation doses from inhaled thorium that was retained in the body and investigated whether any differences in health or biologic indices could have been attributable to the welding and tip-grinding process. Sixty-four TIG welders, 11 non-TIG welders, and 61 control subjects from an airline engineering population participated. All of the subjects were interviewed for biographic, occupational history and morbidity details. All of the welders and eight control subjects carried out large-volume urine sampling to recover thorium 232 and thorium 228; this group also had chest radiographs. All of the subjects had a blood sample taken to estimate liver enzymes, and they provided small-volume urine samples for the estimation of retinol-binding protein and beta 2-microglobulin. We found no excess of morbidity among the TIG or non-TIG welding groups, and the levels of retinol-binding protein and beta 2-microglobulin were the same for both groups. There was a higher aspartate aminotransferase level in the control group. The internal radiation doses were estimated at less than an annual level of intake in all cases, and considerably less if the exposure (as was the case) was assumed to be chronic over many years. Some additional precautionary measures are suggested to reduce further any potential hazard from this process. PMID:8396174

McElearney, N; Irvine, D

1993-07-01

115

Comparison of methods for separating small quantities of hydrogen isotopes from an inert gas  

SciTech Connect

It is frequent within tritium processing systems that a small amount of hydrogen isotopes (Q{sub 2}) must be separated from an inert gas such as He, Ar and N{sub 2}. Thus, a study of presently available technologies for effecting such a separation was performed. A base case and seven technology alternatives were identified and a simple design of each was prepared. These technologies included oxidation-adsorption-metal bed reduction, oxidation-adsorption-palladium membrane reactor, cryogenic adsorption, cryogenic trapping, cryogenic distillation, hollow fiber membranes, gettering and permeators. It was found that all but the last two methods were unattractive for recovering Q{sub 2} from N{sub 2}. Reasons for technology rejection included (1) the method unnecessarily turns the hydrogen isotopes into water, resulting in a cumbersome and more hazardous operation, (2) the method would not work without further processing, and (3) while the method would work, it would only do so in an impractical way. On the other hand, getters and permeators were found to be attractive methods for this application. Both of these methods would perform the separation in a straightforward, essentially zero-waste, single step operation. The only drawback for permeators was that limited low-partial Q{sub 2} pressure data is available. The drawbacks for getters are their susceptibility to irreversible and exothermic reaction with common species such as oxygen and water, and the lack of long-term operation of such beds. More research is envisioned for both of these methods to mature these attractive technologies.

Willms, R.S.; Tuggle, D.; Birdsell, S.; Parkinson, J.; Price, B. [Los Alamos National Lab., NM (United States); Lohmeir, D. [Savannah River Site, Aiken, SC (United States)

1998-03-01

116

Mobility of Supercooled liquid Toluene, Ethylbenzene, and Benzene near their Glass Transition Temperatures Investigated using Inert Gas Permeation  

SciTech Connect

We investigate the mobility of supercooled liquid toluene, ethylbenzene, and benzene near their respective glass transition temperatures (Tg). The permeation rate of Ar, Kr, and Xe through the supercooled liquid created when initially amorphous overlayers heated above their glass transition temperature is used to determine the diffusivity. Amorphous benzene crystallizes at temperatures well below its Tg and as a result the inert gas underlayer remains trapped until the onset of benzene desorption. In contrast, for toluene and ethylbenzene the onset of inert gas permeation is observed at temperatues near Tg. The inert gas desorption peak temperature as a function of the heating rate and overlayer thickness is used to quantify the diffusivity of supercooled liquid toluene and ethylbenzene from 115 K to 135 K. In this temperature range, diffusivities are found to vary across five orders of magnitude (~10-14 to 10-9 cm2/s). These data are compared to viscosity measurements and used to determine the low temperature fractional Stokes-Einstein exponent. Efforts to determine the diffusivity of a mixture of benzene and ethylbenzene are detailed, and the effect of mixing these materials on benzene crystallization is explored using infrared spectroscopy.

May, Robert A.; Smith, R. Scott; Kay, Bruce D.

2013-11-21

117

Compatibility of Space Nuclear Power Plant Materials in an Inert He/Xe Working Gas Containing Reactive Impurities  

SciTech Connect

A major materials selection and qualification issue identified in the Space Materials Plan is the potential for creating materials compatibility problems by combining dissimilar reactor core, Brayton Unit and other power conversion plant materials in a recirculating, inert He/Xe gas loop containing reactive impurity gases. Reported here are results of equilibrium thermochemical analyses that address the compatibility of space nuclear power plant (SNPP) materials in high temperature impure He gas environments. These studies provide early information regarding the constraints that exist for SNPP materials selection and provide guidance for establishing test objectives and environments for SNPP materials qualification testing.

MM Hall

2006-01-31

118

Reflux condenser mode with non-condensible gas: assessment of CATHARE against BETHSY test 7.2C.  

National Technical Information Service (NTIS)

The condensation process in the Steam Generator (SG) U-tubes with the presence of non-condensable gas (nitrogen) has been investigated on the Bethsy integral test facility. Bethsy test 7.2c dealing with Reflux Condenser mode consists of a succession of st...

B. Noel R. Deruaz

1993-01-01

119

Reactive Transport Modeling of Acid Gas Generation and Condensation  

SciTech Connect

Pulvirenti et al. (2004) recently conducted a laboratory evaporation/condensation experiment on a synthetic solution of primarily calcium chloride. This solution represents one potential type of evaporated pore water at Yucca Mountain, Nevada, a site proposed for geologic storage of high-level nuclear waste. These authors reported that boiling this solution to near dryness (a concentration factor >75,000 relative to actual pore waters) leads to the generation of acid condensate (pH 4.5) presumably due to volatilization of HCl (and minor HF and/or HNO{sub 3}). To investigate the various processes taking place, including boiling, gas transport, and condensation, their experiment was simulated by modifying an existing multicomponent and multiphase reactive transport code (TOUGHREACT). This code was extended with a Pitzer ion-interaction model to deal with high ionic strength. The model of the experiment was set-up to capture the observed increase in boiling temperature (143 C at {approx}1 bar) resulting from high concentrations of dissolved salts (up to 8 m CaCl{sub 2}). The computed HCI fugacity ({approx} 10{sup -4} bars) generated by boiling under these conditions is not sufficient to lower the pH of the condensate (cooled to 80 and 25 C) down to observed values unless the H{sub 2}O mass fraction in gas is reduced below {approx}10%. This is because the condensate becomes progressively diluted by H{sub 2}O gas condensation. However, when the system is modeled to remove water vapor, the computed pH of instantaneous condensates decreases to {approx}1.7, consistent with the experiment (Figure 1). The results also show that the HCl fugacity increases, and calcite, gypsum, sylvite, halite, MgCl{sub 2}4H{sub 2}O and CaCl{sub 2} precipitate sequentially with increasing concentration factors.

G. Zhahg; N. Spycher; E. Sonnenthal; C. Steefel

2005-01-25

120

Irreversible wall collisions and thermalization of a gas of inert atoms  

Microsoft Academic Search

Reflection of inert, charge-neutral, spherical atoms from a fixed solid wall with cubic symmetry at low temperature is considered. Working in the limit of classical trajectories, a condition is stated for the irreversibility of reflections, in terms of inelastic energy exchange with wall phonons, from which two classes of atomic energies are implied: I and R. It is found that

Richard L Liboff

1995-01-01

121

Condensate Wave Function of a Trapped Atomic Gas.  

National Technical Information Service (NTIS)

We discuss various properties of the ground state of a Bose-condensed dilute gas confined by an external potential. We devote particular attention to the role played by the interaction in determining the kinetic energy of the system and the aspect ratio o...

F. Dalfovo L. Pitaevskii S. Stringari

1996-01-01

122

Gasification of a Condensed Material in a Hot Gas.  

National Technical Information Service (NTIS)

A theoretical analysis is presented for the gasification process of a condensed material suddenly exposed to a hot stagnant gas. When the gasification rate is given by an Arrhenius law the surface temperature rises to the non-gasification jump value upon ...

M. Kindelan A. Linan

1976-01-01

123

Laboratory Evaporation of Hanford Waste Treatment Plant Low Activity Waste Off-Gas Condensate Simulant.  

National Technical Information Service (NTIS)

The Hanford Waste Treatment and Immobilization Plant (WTP) Low Activity Waste (LAW) vitrification facility will generate an aqueous condensate recycle stream, LAW Off-Gas Condensate, from the off-gas system. The baseline plan for disposition of this strea...

C. A. Nash C. L. Crawford D. J. Adamson D. J. McCabe W. R. Wilmarth

2014-01-01

124

Condensation  

NSDL National Science Digital Library

In this activity, learners explore the process of condensation. After seeing water vapor condense, learners will help design a test to see if cooling water vapor has an effect on the rate of condensation.

Kessler, James H.; Galvan, Patricia M.

2007-01-01

125

Method for extending the useful shelf-life of refrigerated red blood cells by flushing with inert gas  

DOEpatents

A method is disclosed using oxygen removal for extending the useful shelf-life of refrigerated red blood cells. A cost-effective, 4 C storage procedure that preserves red cell quality and prolongs post-transfusion in vivo survival is described. Preservation of adenosine triphosphate levels and reduction in hemolysis and in membrane vesicle production of red blood cells stored at 4 C for prolonged periods of time is achieved by removing oxygen from the red blood cells at the time of storage; in particular, by flushing with an inert gas. Adenosine triphosphate levels of the stored red blood cells are boosted in some samples by addition of ammonium phosphate. 4 figs.

Bitensky, M.W.; Yoshida, Tatsuro

1997-04-29

126

Method for extending the useful shelf-life of refrigerated red blood cells by flushing with inert gas  

DOEpatents

Method using oxygen removal for extending the useful shelf-life of refrigerated red blood cells. A cost-effective, 4.degree. C. storage procedure that preserves red cell quality and prolongs post-transfusion in vivo survival is described. Preservation of adenosine triphosphate levels and reduction in hemolysis and in membrane vesicle production of red blood cells stored at 4.degree. C. for prolonged periods of time is achieved by removing oxygen therefrom at the time of storage; in particular, by flushing with an inert gas. Adenosine triphosphate levels of the stored red blood cells are boosted in some samples by addition of ammonium phosphate.

Bitensky, Mark W. (Los Alamos, NM); Yoshida, Tatsuro (Los Alamos, NM)

1997-01-01

127

Modeling condensation with a noncondensable gas for mixed convection flow  

NASA Astrophysics Data System (ADS)

This research theoretically developed a novel mixed convection model for condensation with a noncondensable gas. The model developed herein is comprised of three components: a convection regime map; a mixed convection correlation; and a generalized diffusion layer model. These components were developed in a way to be consistent with the three-level methodology in MELCOR. The overall mixed convection model was implemented into MELCOR and satisfactorily validated with data covering a wide variety of test conditions. In the development of the convection regime map, two analyses with approximations of the local similarity method were performed to solve the multi-component two-phase boundary layer equations. The first analysis studied effects of the bulk velocity on a basic natural convection condensation process and setup conditions to distinguish natural convection from mixed convection. It was found that the superimposed velocity increases condensation heat transfer by sweeping away the noncondensable gas accumulated at the condensation boundary. The second analysis studied effects of the buoyancy force on a basic forced convection condensation process and setup conditions to distinguish forced convection from mixed convection. It was found that the superimposed buoyancy force increases condensation heat transfer by thinning the liquid film thickness and creating a steeper noncondensable gas concentration profile near the condensation interface. In the development of the mixed convection correlation accounting for suction effects, numerical data were obtained from boundary layer analysis for the three convection regimes and used to fit a curve for the Nusselt number of the mixed convection regime as a function of the Nusselt numbers of the natural and forced convection regimes. In the development of the generalized diffusion layer model, the driving potential for mass transfer was expressed as the temperature difference between the bulk and the liquid-gas interface using the Clausius-Clapeyron equation. The model was developed on a mass basis instead of a molar basis to be consistent with general conservation equations. It was found that vapor diffusion is not only driven by a gradient of the molar fraction but also a gradient of the mixture molecular weight at the diffusion layer.

Liao, Yehong

128

Determination of water in hydrogen chloride gas by a condensation technique  

SciTech Connect

The determination of trace amounts of water in gaseous hydrogen chloride has been of considerable interest to manufacturers of semiconductor materials. Many different methods have been postulated in the detection of water in hydrogen chloride, including Karl Fischer titrations, infrared spectrometric techniques, and gravimetric procedures using desiccants. Despite varying degrees of success at high-moisture concentration ranges, 1000 ppm (v/v) and up, these methods become tedious and unreliable for measuring water in hydrogen chloride in the 1-1000 ppm range. We have found a method for moisture in hydrogen chloride, analogous to dew point determinations used for inert gases, that is rapid and reproducible. A calibration curve of parts per million (v/v) water in hydrogen chloride vs. condensation temperature was constructed by dynamically blending a low part per million moisture balance nitrogen standard with dried hydrogen chloride gas. In addition, variation of the condensation temperature was monitored as the dried hydrogen chloride was diluted with dried gaseous nitrogen.

Flaherty, E.; Herold, C.; Murray, D.; Thompson, S.R.

1986-07-01

129

Calculation of minimum miscibility pressure for gas condensate reservoirs  

Microsoft Academic Search

This work focuses on analytical calculation of MMP for gas condensate reservoirs. For the sake of simplicity, the method outlined by Wang [Y. Wang, Doctoral Dissertation, Stanford University, USA, 1998] and pseudo-components are used for calculating MMP. We evaluated this method using the Peng–Robinson EOS, Patel–Teja EOS, Patel–Teja–Valderrama EOS, and the Esmaeilzadeh–Roshanfekr EOS and compared it with the experimental data.

F. Esmaeilzadeh; M. Roshanfekr

2006-01-01

130

Development of a Market Optimized Condensing Gas Water Heater  

SciTech Connect

This program covered the development of a market optimized condensing gas water heater for residential applications. The intent of the program was to develop a condensing design that minimized the large initial cost premium associated with traditional condensing water heater designs. Equally important was that the considered approach utilizes design and construction methods that deliver the desired efficiency without compromising product reliability. Standard condensing water heater approaches in the marketplace utilize high cost materials such as stainless steel tanks and heat exchangers as well as expensive burner systems to achieve the higher efficiencies. The key in this program was to develop a water heater design that uses low-cost, available components and technologies to achieve higher efficiency at a modest cost premium. By doing this, the design can reduce the payback to a more reasonable length, increasing the appeal of the product to the marketplace. Condensing water heaters have been in existence for years, but have not been able to significantly penetrate the market. The issue has typically been cost. The high purchase price associated with existing condensing water heaters, sometimes as much as $2000, has been a very difficult hurdle to overcome in the marketplace. The design developed under this program has the potential to reduce the purchase price of this condensing design by as much as $1000 as compared to traditional condensing units. The condensing water heater design developed over the course of this program led to an approach that delivered the following performance attributes: 90%+ thermal efficiency; 76,000 Btu/hr input rate in a 50 gallon tank; First hour rating greater than 180 gph; Rapid recovery time; and Overall operating condition well matched to combination heat and hot water applications. Over the final three years of the program, TIAX worked very closely with A.O. Smith Water Products Company as our commercial partner to optimize the design for manufacturing. This work included the initiation of a large field testing program (over 125 units) and an in-depth reliability program intended to minimize the risks associated with a new product introduction. At the time of this report, A.O. Smith plans to introduce this product to the marketplace in the early 2006 time period.

Peter Pescatore

2006-01-11

131

A method for calculating regional cerebral blood flow from emission computed tomography of inert gas concentrations  

SciTech Connect

Emission tomography of positron or gamma emitting inert gases allows calculation of regional cerebral blood flow (rCBF) in cross-sectional slices of human brain. An algorithm is presented for rCBF calculations from a sequence of time averaged tomograms using inhaled 133Xe. The approach is designed to avoid loss of information in brain areas with low flow rates. It is based on linearizing and scaling the early isotope distribution picture (recorded from 0 to 2 min) in rCBF units of ml/100 g/min. This is done by calculating the time constant ki for pixels with high count rate using the entire sequence of four 1 min pictures and using a fixed value for the brain:blood partition coefficient, lambda. The method is essentially based on the bolus distribution principle, and it allows the estimation of blood flow in ischemic areas. Application to positron emission tomography is discussed.

Celsis, P.; Goldman, T.; Henriksen, L.; Lassen, N.A.

1981-10-01

132

Calculation of hydrocarbon-in-place in gas and gas-condensate reservoirs - Carbon dioxide sequestration  

USGS Publications Warehouse

The Energy Independence and Security Act of 2007 (Public Law 110-140) authorized the U.S. Geological Survey (USGS) to conduct a national assessment of geologic storage resources for carbon dioxide (CO2), requiring estimation of hydrocarbon-in-place volumes and formation volume factors for all the oil, gas, and gas-condensate reservoirs within the U.S. sedimentary basins. The procedures to calculate in-place volumes for oil and gas reservoirs have already been presented by Verma and Bird (2005) to help with the USGS assessment of the undiscovered resources in the National Petroleum Reserve, Alaska, but there is no straightforward procedure available for calculating in-place volumes for gas-condensate reservoirs for the carbon sequestration project. The objective of the present study is to propose a simple procedure for calculating the hydrocarbon-in-place volume of a condensate reservoir to help estimate the hydrocarbon pore volume for potential CO2 sequestration.

Verma, Mahendra K.

2012-01-01

133

Integrated Gas Condensate Processing Scheme at the Sosnogorsk Gas Processing Plant  

Microsoft Academic Search

Unstable gas condensate of the Vuktyl group of fields is the primary hydrocarbon raw (feed) materials that are processable at the Sosnogorsk Gas Processing Plant (GPP) in the Komi Republic. The suitability of processing hydrocarbon raw materials of these fields is supported by their high content of liquefied gases (propane and butane) as well as of C 5+ hydrocarbons. The

M. A. Kudryavtsev; M. P. Lapshin; S. V. Shurupov; N. N. Kislenko; A. V. Shestoperova; S. V. Savchenkov

2002-01-01

134

Microstructural investigations of rapidly solidified Cu-Nb alloy powders produced by inert-gas atomization. Technical report  

SciTech Connect

This study presents a metallographic technique which enables the microstructural examination of the cross-sections of individual, fine-scale (10-75 um) powder particles. The technique was developed to permit characterization of the as-solidified features of Cu-based powders produced by high pressure inert gas atomization in order to relate the microstructures to processing history. In order to perform the necessary microscopy to elucidate the microstructural features, a metallographic technique was developed to permit characterization of the as-atomized microstructures within the individual powder particles. This technique involved classifying, mounting, and polishing through the diameters of individual powder particles and then using an attack etch to remove some of the copper matrix. This enabled characterization of the niobium-rich second phase. Secondary electron imaging on a scanning electron microscope provided the necessary resolution to characterize the second phase morphologies as a function powder-particle size, ultimately relating the microstructures to processing conditions.

Zeik, K.L.; Anderson, I.E.; Koss, D.A.; Howell, P.R.

1991-04-30

135

Computation of decompression schedules for single inert gas-oxygen dives using a hand-held programmable calculator.  

PubMed

An algorithm for on-site computation with a hand-held programmable calculator (TI-59, Texas Instruments) of single inert-gas decompression schedules is described. This program is based on Workman's 'M-value' method. It can compute decompression schedules with changes in the oxygen content of the breathing mixture and extension of stay at any decompression stop. The features of the program that enable calculation of atypical dive profiles, along with the portability of small calculators, would make such an algorithm suitable for on-site applications. However, since dive profiles generated by the program have not yet been tested, divers are warned not to generate schedules until their safety has been established by field tests. PMID:6257447

Ranade, A; Peterson, R E

1980-08-01

136

A buffer-gas cooled Bose-Einstein condensate  

NASA Astrophysics Data System (ADS)

We report the creation of a Bose-Einstein condensate using buffer-gas cooling, the first realization of BEC using a method which relies neither on laser cooling nor unique atom-surface properties. Metastable helium ( 4He*) is buffer-gas cooled and magnetically trapped using an optimized buffer-gas trapping apparatus, followed by evaporative cooling to quantum degeneracy. Evaporative cooling proceeds in two stages, each traversing approximately five orders of magnitude in phase space density. An initial stage of evaporation uses a surface to adsorb atoms, while a later stage uses radio-frequency induced spin-flips to evaporate atoms. Trapped atoms are detected using absorption and phase-contrast imaging both in-situ and in time-of-flight expansion. 1011 atoms are initially trapped, leading to Bose-Einstein condensation at a critical temperature of 5 muK and threshold atom number of 1.1 x 106. The method developed here is applicable to a wide array of paramagnetic atoms as well as molecules, many of which are impractical to laser cool and all of which are impossible to surface cool.

Doret, Stephen Charles

137

Federal helium program: The reaction over an inert gas. Final report  

SciTech Connect

Helium, present in relatively high concentrations in only a few natural gas fields, is released to the atmosphere and wasted when the natural gas is burned as fuel. Government involvement in helium conservation dates to the Helium Act of 1925 which authorized the Bureau of Mines to build and operate a large-scale helium extraction and purification plant. From 1929 until 1960 the federal government was the only domestic helium producer. In 1960, Congress amended the Helium Act to provide incentives to natural gas producers for stripping natural gas of its helium, for purchase of the separated helium by the government, and for its long-term storage. With over 960 million cubic meters (34.6 billion cubic feet) of helium in government storage and a large private helium recovery industry, questions arise as to the need for either the federal helium extraction program or the federally maintained helium stockpile.

Mielke, J.E.

1996-10-09

138

Effects of inert species in the gas phase in a model for the catalytic oxidation of CO.  

PubMed

We study by kinetic Monte Carlo simulations the catalytic oxidation of carbon monoxide on a surface in the presence of contaminants in the gas phase. The process is simulated by a Ziff-Gulari-Barshad (ZGB) model that has been modified to include the effect of the contaminants and to eliminate an unphysical oxygen poisoned phase at very low CO partial pressures. The impurities can adsorb and desorb on the surface but otherwise remain inert. We find that if the impurities cannot desorb, no matter how small their proportion in the gas mixture, the reactive window and discontinuous transition to a CO poisoned phase at high CO pressures that characterize the original ZGB model disappear. The coverages become continuous, and once the surface has reached a steady state there is no production of CO(2). This is quite different from the behavior of systems in which the surface presents a fixed percentage of impurities. When the contaminants are allowed to desorb, the reactive phase appears again for CO pressures below a value that depends on the proportion of contaminants in the gas and on their desorption rate. PMID:22587074

Buendķa, G M; Rikvold, P A

2012-03-01

139

Inert gas stratigraphy of Apollo 15 drill core sections 15001 and 15003  

NASA Technical Reports Server (NTRS)

Rare gase contents were studied in Apollo 15 drill core sections corresponding to 207 to 238 and 125 to 161-cm depths, with respect to layering of the core, turnover on a centimeter scale, and cosmic proton bombardment history. Trapped gas abundance was established in all samples, the mean grain size being a major factor influencing the absolute rare gas contents. Analysis of the results suggests that the regolith materials were exposed to galactic and solar cosmic rays long before their deposition.

Huebner, W.; Kirsten, T.; Heymann, D.

1973-01-01

140

Nucleation and growth of Nb nanoclusters during plasma gas condensation  

SciTech Connect

Niobium nanoclusters were produced using a plasma gas condensation process. The influence of gas flow rate, aggregation length, and source current on the nanocluster nucleation and growth were analyzed. Nanoclusters with an average diameter from 4 nm to 10 nm were produced. Cluster size and concentration were tuned by controlling the process inputs. The effects of each parameter on the nucleation zone, growth length, and residence time was examined. The parameters do not affect the cluster formation and growth independently; their influence on cluster formation can be either cumulative or competing. Examining the nucleation and growth over a wide combination of parameters provided insight into their interactions and the impact on the growth process. These results provide the opportunity for a broader understanding into the nucleation and growth of nanoclusters and some insights into how process parameters interact during deposition. This knowledge will enhance the ability to create nanoclusters with desired size dispersions.

Bray, K. R.; Jiao, C. Q. [UES, Inc., 4401 Dayton-Xenia Rd, Dayton, Ohio 45432 (United States)] [UES, Inc., 4401 Dayton-Xenia Rd, Dayton, Ohio 45432 (United States); DeCerbo, J. N. [Air Force Research Laboratory, AFRL/RQQE, 1950 Fifth St., WPAFB, Ohio 45433 (United States)] [Air Force Research Laboratory, AFRL/RQQE, 1950 Fifth St., WPAFB, Ohio 45433 (United States)

2013-06-21

141

Bose Einstein condensation in a gas of Fibonacci oscillators  

NASA Astrophysics Data System (ADS)

We consider a system of two-parameter deformed boson oscillators whose spectrum is given by a generalized Fibonacci sequence. In order to establish the role of the deformation parameters (q1,q2) in the thermostatistics of the system, we calculate several thermostatistical functions in the thermodynamical limit and investigate the low temperature behavior of the system. In this framework, we show that the thermostatistics of the (q1,q2)-bosons can be studied using the formalism of Fibonacci calculus which generalizes the recently proposed formalism of q-calculus. We also discuss the conditions under which the Bose-Einstein condensation would occur in the present two-parameter generalized boson gas. However, the ordinary boson gas results can be obtained by applying the limit q1 = q2 = 1.

Algin, Abdullah

2008-10-01

142

Modelling the multiphase flow of an oil–gas–condensate system in porous media  

Microsoft Academic Search

The “Black oil” model is extended to describe the four-phase flow of the oil-gas–condensate systems in porous media, by considering the solubilities of gas in the condensate, water, and oil phases and condensate evaporation into the gas phase. The three-dimensional transient-state model equations are reduced to one-dimensional transient-state forms by the partial integration method. The finite-difference method is used for

B. Kh. Khuzhayorov; V. F. Burnashev

2001-01-01

143

Combustion of bulk density powder mixtures in a coflow of inert gas: 6*(Fe 2 O 3 + 2Al) + 30% Al 2 O 3 mixtures  

Microsoft Academic Search

Investigated was the combustion of bulk density (Fe2O3 + 2Al) + 30% Al2O3 mixtures in a coflow of inert gas (Ar) in the presence\\/absence of blowing agents (borax, baking soda) and applied pressure\\u000a difference ?P. The results have been rationalized in terms of the conduction-convection theory for combustion in heterogeneous systems.

G. B. Brauer; A. G. Tarasov; B. S. Seplyarskii

2009-01-01

144

Observation of the trapping of radioactive inert gas radon on oxide glass surfaces: Macroporous scintillating-glass-fiber bundler alpha detector  

Microsoft Academic Search

We report the observation of the trapping of radioactive inert gas radon (222Rn) on oxide glass under ambient air temperature and pressure of 300 K and 760 Torr, respectively. Radon diffuses from the source, through two macroporous scintillating-glass-fiber bundle alpha detectors in series, to the end of the linear closed system filled with ambient air. The strategy is to provide

I. S. Kim; A. Appleby; G. H. Sigel

1997-01-01

145

Observation of the trapping of radioactive inert gas radon on oxide glass surfaces: Macroporous scintillating-glass-fiber bundle alpha detector  

Microsoft Academic Search

We report the observation of the trapping of radioactive inert gas radon (222Rn) on oxide glass under ambient air temperature and pressure of 300 K and 760 Torr, respectively. Radon diffuses from the source, through two macroporous scintillating-glass-fiber bundle alpha detectors in series, to the end of the linear closed system filled with ambient air. The strategy is to provide

I. S. Kim; A. Appleby; G. H. Sigel Jr.

1997-01-01

146

Modeling and analyzing the effects of heat treatment on the characteristics of magnesium alloy joint welded by the tungsten-arc inert gas welding  

Microsoft Academic Search

The objective of this paper is to present the mathematical models for modeling and analysis of the effects of heat treatment on the characteristics of magnesium alloy joint welded by the tungsten-arc inert gas (TIG) welding. The process of heat treatment adopts the tempering process with varying processing parameters, including tempering temperature and tempering time. The microstructure and mechanical properties

Te-Chang Tsai; Chih-Chung Chou; Deng-Maw Tsai; Ko-Ta Chiang

2011-01-01

147

EFFECT OF VENTILATION AND PERFUSION IMBALANCE ON INERT GAS REBREATHING VARIABLES  

EPA Science Inventory

The effects of ventilation-to-perfusion (Va/Qc) maldistribution within the lungs on measured multiple gas rebreathing variables were studied in 14 dogs. The rebreathing method (using He, C18C, and C2H2) allows for measurements of pulmonary capillary blood flow (Qc), diffusing cap...

148

Comparison of water-based foam and inert-gas mass emergency depopulation methods.  

PubMed

Current control strategies for avian influenza (AI) and other highly contagious poultry diseases include surveillance, quarantine, depopulation, disposal, and decontamination. Selection of the best method of emergency mass depopulation involves maximizing human health and safety while minimizing disease spread and animal welfare concerns. Proper selection must ensure that the method is compatible with the species, age, housing type, and disposal options. No one single method is appropriate for all situations. Gassing is one of the accepted methods for euthanatizing poultry. Whole-house, partial-house, or containerized gassing procedures are currently used. The use of water-based foam was developed for emergency mass depopulation and was conditionally approved by the United States Department of Agriculture in 2006. Research has been done comparing these different methods; parameters such as time to brain death, consistency of time to brain death, and pretreatment and posttreatment corticosterone stress levels were considered. In Europe, the use of foam with carbon dioxide is preferred over conventional water-based foam. A recent experiment comparing CO2 gas, foam with CO2 gas, and foam without CO2 gas depopulation methods was conducted with the use of electroencephalometry results. Foam was as consistent as CO2 gassing and more consistent than argon-CO2 gassing. There were no statistically significant differences between foam methods. PMID:20521728

Alphin, R L; Rankin, M K; Johnson, K J; Benson, E R

2010-03-01

149

Quantum hydrodynamics in dilute-gas Bose-Einstein condensates  

NASA Astrophysics Data System (ADS)

The peculiar dynamics of superfluids are a fascinating research topic. Since the first generation of a dilute gas Bose-Einstein condensate (BEC) in 1995, quantum degenerate atomic gases have taken the investigation of quantum hydrodynamics to a new level. The atomic physics toolbox has grown tremendously and now provides unique and powerful ways to explore nonlinear quantum systems. As an example, pioneering results have recently revealed that the counterflow between two superfluids can be used as a well controlled tool to access the rich dynamics of vector systems. New structures, such as beating dark-dark solitons which only exist in multicomponent systems and have never been observed before, can now be realized in the lab for the first time. Furthermore, the field of nonlinear quantum hydrodynamics is entering new regimes by exploiting Raman dressing as a tool to directly modify the dispersion relation. This leads to the generation of spin-orbit coupled BECs, artificial gauge fields, etc. that are currently receiving tremendous interest due to their parallels to complex condensed-matter systems. Studies of quantum hydrodynamics help to develop a profound understanding of nonlinear quantum dynamics, which is not only of fundamental interest but also of eminent importance for future technological applications, e.g. in telecommunication applications using optical solitons in fibers. This talk will showcase some ``classic'' hallmark results and highlight recent advances from the forefront of the field.

Engels, Peter

2012-10-01

150

Nonlinear resonant gas oscillation accompanied with evaporation and condensation  

NASA Astrophysics Data System (ADS)

Resonant gas oscillation in a closed tube bounded by an oscillating plate and a vapor-liquid interface is theoretically analyzed by applying the asymptotic theory to the ES-BGK Boltzmann equation for the case of MP ~ Kn << 1 and a small evaporation coefficient ? = O(Kn), where MP and Kn are the Mach number of the plate and the Knudsen number, respectively. As a result, we derive a nonlinear integro-differential equation for determining the wave profile with the evaporation and condensation including ?. We numerically solve the integro-differential equation with the method of Fourier series, and obtain a parameter plane for shock formation conditions and also the prediction of critical condition for shock formation.

Inaba, Masashi; Yano, Takeru; Kobayashi, Kazumichi; Watanabe, Masao

2012-11-01

151

Synchrotron X-ray measurement and finite element analysis of residual strain in tungsten inert gas welded aluminum alloy 2024  

NASA Astrophysics Data System (ADS)

Residual strains have been measured in a tungsten inert gas (TIG) butt-welded 2024 aluminum alloy plate using synchrotron X-ray diffraction. Novel two-dimensional strain maps spanning the entire plate reveal steep gradients in residual stress and provide detailed validation data for finite element (FE) analysis. Two variants of a FE model have been used to predict the residual strain distributions, incorporating different levels of plate constraint. The model uses decoupled thermal and elastic-plastic mechanical analyses and successfully predicts the longitudinal and transverse residual strain field over the entire weld. For butt weld geometries, the degree of transverse constraint is shown to be a significant boundary condition, compared to simpler bead-on-plate analyses. The importance of transverse residual strains for detailed model validation is highlighted, together with the need for care in selecting the location for line scans. The residual stress is largest in the heat-affected zone (HAZ), being equal to the local postweld yield stress, though the strength increases subsequently by natural aging. In addition, a halving of the diffraction line width has been observed local to the weld, and this correlates with the microstructural changes in the region.

Preston, R. V.; Shercliff, H. R.; Withers, P. J.; Hughes, D. J.; Smith, S. D.; Webster, P. J.

2006-12-01

152

Precipitate microstructures and resulting properties of Al-Zn-Mg metal inert gas-weld heat-affected zones  

NASA Astrophysics Data System (ADS)

Using the combination of small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), the precipitate microstructure is quantitatively investigated in the heat-affected zones (HAZs) of Al-Zn-Mg metal inert gas (MIG)-welds, and the resulting mechanical properties are determined by hardness measurements. Three initial states prior to welding (T4, T6, and T7) are investigated, and the subsequent microstructure evolution during natural aging and postwelding heat treatments (PWHTs) is assessed. The critical part of the HAZ is shown to be the transition region where partial dissolution of the initially present precipitates occurs. In this transition zone, precipitate coarsening is shown to occur for the T6 and T7 initial states, contrarily to the T4 material. After PWHT, the T6 and T7 materials experience a weak region related to this coarsening behavior, whereas the T4 material HAZ is able to recover a homogeneous microstructure after a suitably chosen PWHT. Simple model ramp heat treatments are shown to describe the main phenomena involved in the HAZ. Finally, a precipitation hardening model is successfully applied to the microstructural data to describe the hardness profiles in the various HAZs.

Nicolas, M.; Deschamps, A.

2004-05-01

153

Abnormal distribution of microhardness in tungsten inert gas arc butt-welded AZ61 magnesium alloy plates  

SciTech Connect

In this study, the effects of heat input on the distribution of microhardness of tungsten inert gas (TIG) arc welded hot-extruded AZ61 magnesium alloy joints were investigated. The results show that with an increase of heat input, the distributions of microhardness at the top and bottom of the welded joints are different because they are determined by both the effect of grain coarsening and the effect of dispersion strengthening. With an increase of the heat input, the microhardness of the heat-affected zone (HAZ) at the top and bottom of welded joints and the fusion zone (FZ) at the bottom of welded joints decreased gradually, while the microhardness of the FZ at the top of welded joints decreased initially and then increased sharply. The reason for the abnormal distribution of microhardness of the FZ at the top of the welded joints is that this area is close to the heat source during welding and then large numbers of hard {beta}-Mg{sub 17}(Al,Zn){sub 12} particles are precipitated. Hence, in this case, the effect of dispersion strengthening dominated the microhardness.

Xu Nan [College of Material Science and Engineering, Chongqing University, Chongqing 400044 (China); Shen Jun, E-mail: shenjun2626@163.com [College of Material Science and Engineering, Chongqing University, Chongqing 400044 (China); Xie Weidong; Wang Linzhi; Wang Dan; Min Dong [College of Material Science and Engineering, Chongqing University, Chongqing 400044 (China)

2010-07-15

154

Ultrasonic and resistive hydrogen sensors for inert gas-water vapour atmospheres  

NASA Astrophysics Data System (ADS)

Hydrogen concentration measurements were developed for a series of experiments in which a molten oxide is mixed with water to study vapour explosion phenomena. The gas mixture to be analysed consisted of hydrogen with water vapour and either helium or argon. Two types of sensor have been developed for these tests. The first is an ultrasonic sensor, which detects variations in the acoustic velocity within a 0.4 mm-diameter palladium wire. The sensor measures hydrogen concentrations in the range 0.1-100%, at atmospheric pressure, over an operating temperature range of 200-400 °C. The response time (for 0-90% of the final response) is about 30 s at 180 °C and 8 s at 380 °C. The second sensor consists of a palladium coil, constructed with 0.05 mm-diameter wire that is wound around a ceramic tube. Measurements of wire resistance were used to detect partial pressure of hydrogen. This sensor operates at 150-300 °C and measures hydrogen concentrations of 1-100%. The response time is short, 1-2 s for a temperature of 300 °C.

Lomperski, S.; Anselmi, M.; Huhtiniemi, I.

2000-05-01

155

Observation of deviations from ideal gas thermodynamics in a trapped Bose-Einstein condensed gas  

Microsoft Academic Search

We have investigated experimentally the finite-temperature properties of a\\u000aBose-Einstein condensed cloud of $^{87}$Rb atoms in a harmonic trap. Focusing\\u000aprimarily on condensed fraction and expansion energy, we measure unambiguous\\u000adeviations from ideal-gas thermodynamics, and obtain good agreement with a\\u000aHartree-Fock description of the mixed cloud. Our results offer for the first\\u000atime clear evidence of the mutual interaction between

Fabrice Gerbier; Joseph H. Thywissen; Simon Richard; Mathilde Hugbart; Philippe Bouyer; Alain Aspect

2004-01-01

156

Effects of ventilation on cardiac output determined by inert gas rebreathing.  

PubMed

One of the most important methodological problems of the foreign gas rebreathing technique is that outcome of the measurements depends on procedural variables such as rebreathing frequency (RF), rebreathing bag volume (V(reb)), lung volume at start of rebreathing and intervals between measurements. Therefore, in 10 healthy males we investigated the effects of changes in ventilation pattern on cardiac output (CO) estimated by an N(2)O-rebreathing technique. Reducing the rebreathing volume (V(reb)) from 1.5 to 1.0 l diminished CO by 0.5 +/- 0.2 l min(-1), whereas an increase in V(reb) from 1.5 to 2.5 l had no effects. CO was 1.0 +/- 0.2 l min(-1) higher when, rebreathing was performed after a forced expiration than following a normal tidal expiration. Serial determinations of CO required a 3-min interval between the measurements to avoid effects of recirculation of N(2)O. Changing RF from 15 to 30 breaths min(-1) or adding serial dead space by up to 600 ml did not affect the determination of CO. In conclusion, the rebreathing procedure for determination of CO at rest should be performed following a normal tidal expiration with a rebreathing bag volume of between 1.5 and 2.5 l and with manoeuvres separated by at least 3-5 min. Variations in RF within the physiological range from 15 to 30 breaths min(-1) do not affect outcome of the measurements. PMID:15888093

Damgaard, Morten; Norsk, Peter

2005-05-01

157

Preliminary evaluation of adsorbent-based mercury removal systems for gas condensate  

Microsoft Academic Search

Mercury can be present in gas condensate in its metallic form and\\/or as organometallic compounds with boiling points comparable to that of the range of the condensate. The damage caused to industrial plants, particularly petrochemical plants, by the presence of certain mercury species can be financially crippling especially when unscheduled shut-downs are forced. Speciation of the mercury content of gas

Azman Shafawi; Les Ebdon; Mike Foulkes; Peter Stockwell; Warren Corns

2000-01-01

158

Interface conditions governing evaporation of stored liquids in presence of non-condensable gas  

Microsoft Academic Search

Experiments were conducted to determine the variation of interface temperatures during the storage and draining of liquid nitrogen from large containers in the presence of the non-condensable gas. A chilled layer was seen to be formed at the interface in the presence of the non-condensable gas and this layer advanced into the warm liquid at speeds higher than the characteristic

K. Ramamurthi; S. Sunil Kumar; B. S. Chaitanya

2006-01-01

159

Non-condensible gas injection including alpha-olefin sulfonate surfactant additives  

SciTech Connect

This patent describes a non-condensible gas process of recovering hydrocarbons from a subterranean formation in the absence of steam, wherein the formation is penetrated by at least one injection well and at least one production well. The process consists of: (a) injecting a non-condensible gas at an injection well until non-condensible gas breakthrough occurs at a production well; (b) continuing to inject into the formation the non-condensible gas and, including therewith and under non-stream conditions, a sufficient amount of alpha-olefin sulfonate to form a non-condensible gas and alpha-olefin sulfonate foam to assist the movement of hydrocarbons toward the production well; and (c) recovering hydrocarbons from the production well.

Duerksen, J.H.; Wall, R.G.; Knight, J.D.

1986-02-25

160

Interfacial microstructure and mechanical properties of aluminium–zinc-coated steel joints made by a modified metal inert gas welding–brazing process  

Microsoft Academic Search

The microstructure and properties of aluminium–zinc coated steel lap joints made by a modified metal inert gas CMT welding–brazing process was investigated. It was found that the nature and the thickness of the high-hardness intermetallic compound layer which formed at the interface between the steel and the weld metal during the welding process varied with the heat inputs. From the

H. T. Zhang; J. C. Feng; P. He; H. Hackl

2007-01-01

161

Brazability of dissimilar metals tungsten inert gas butt welding–brazing between aluminum alloy and stainless steel with Al–Cu filler metal  

Microsoft Academic Search

Dissimilar metals tungsten inert gas butt welding–brazing between 5A06 aluminum alloy and SUS321 stainless steel was carried out using Al–Cu6 filler metal and non-corrosive flux. A thin intermetallic compound layer has formed in welded seam\\/steel interface and the average thickness of the whole layer is 3–5?m, which is less than the limited value of 10?m. The intermetallic compound layer consists

S. B. Lin; J. L. Song; C. L. Yang; C. L. Fan; D. W. Zhang

2010-01-01

162

Method of predicting revaporization of retrograde condensate by dry gas injection  

Microsoft Academic Search

A mathematical model is presented for predicting the revaporization of retrograde condensate liquid by dry gas injection. The primary assumptions in the model are that complete phase equilibrium exists between the gas and liquid in the model, the liquid saturation is less than the mobile liquid saturation, and that the dry gas does not bypass any rich gas as it

Givens

1968-01-01

163

Gas and condensate composition in the deep Tuscaloosa trend, southern Louisiana - influence of oil and wet gas cracking  

Microsoft Academic Search

Natural gas and condensate samples from 34 wells in six fields producing from deep Tuscaloosa sandstones show regular changes in chemical and isotopic composition with increasing depth of burial. A gas-condensate system at 5.2 km (17,000 ft) changes to dry gas at 6.1 km (20,500 ft). Carbon isotopic compositions of ethane and propane become heavier ([delta] [sup 13]C[sub 2] increases

G. E. Claypool; M. A. Rooney; A. K. Vuletich

1996-01-01

164

46 CFR 154.1848 - Inerting.  

Code of Federal Regulations, 2010 CFR

...air is admitted; and (4) When gas free cargo tanks are to be filled...is purged from the tank by inert gas until the oxygen concentration in the tank is 8 percent...vapor is introduced. (b) Inert gas must be supplied from the shore...

2010-10-01

165

Theory of Critical Temperature Adiabatic Change for Ideal Gas Bose-Einstein Condensation in Optical Lattices  

Microsoft Academic Search

We present a scheme of analytical calculations determining the critical temperature and the number of condensed atoms of ideal gas Bose-Einstein condensation in external potentials with 1D, 2D or 3D periodicity. In particular we show that the width of the lowest energy band appears as the main parameter determining the critical temperature of condensation. Is obtained a very simple, proportional

G. A. Muradyan; A. Zh. Muradyan

2006-01-01

166

Crossover from a Bose-Einstein Condensate of Molecules to a Degenerate Fermi Gas of Atoms  

Microsoft Academic Search

We have observed Bose-Einstein condensation of molecules. When a spin mixture of fermionic ^6Li atoms was evaporatively cooled in an optical dipole trap near a Feshbach resonance, the atomic gas was converted into ^6Li2 molecules. Below 600 nK, a Bose-Einstein condensate of up to 900,000 molecules was identified by the sudden onset of a bimodal density distribution. This condensate realizes

Christian H. Schunck; Sebastian M. F. Raupach; Martin W. Zwierlein; Claudiu A. Stan; Andrew J. Kerman; Subhadeep Gupta; Zoran Hadzibabic; Wolfgang Ketterle

2004-01-01

167

AVO in North of Paria, Venezuela: Gas methane versus condensate reservoirs  

SciTech Connect

The gas fields of North of Paria, offshore eastern Venezuela, present a unique opportunity for amplitude variations with offset (AVO) characterization of reservoirs containing different fluids: gas-condensate, gas (methane) and water (brine). AVO studies for two of the wells in the area, one with gas-condensate and the other with gas (methane) saturated reservoirs, show interesting results. Water sands and a fluid contact (condensate-water) are present in one of these wells, thus providing a control point on brine-saturated properties. The reservoirs in the second well consist of sands highly saturated with methane. Clear differences in AVO response exist between hydrocarbon-saturated reservoirs and those containing brine. However, it is also interesting that subtle but noticeable differences can be interpreted between condensate-and methane-saturated sands. These differences are attributed to differences in both in-situ fluid density and compressibility, and rock frame properties.

Regueiro, J. [Univ. Simon Bolivar, Sartenejas (Venezuela)] [Univ. Simon Bolivar, Sartenejas (Venezuela); Pena, A. [Lagoven S.A., Caracas (Venezuela)] [Lagoven S.A., Caracas (Venezuela)

1996-07-01

168

Bose condensation in dilute gas of hard spheres with attraction  

NASA Astrophysics Data System (ADS)

Critical temperature is calculated for Bose-Einstein condensation of hard spheres with attraction using the path-integral Monte Carlo (PIMC) method and finite-size scaling. It is demonstrated that the scattering length is not the only parameter which the critical temperature depends on. It is also shown that Bose condensation may be observed in the case of negative scattering length.

Bronin, S. Y.; Zelener, B. V.; Klyarfeld, A. B.; Filinov, V. S.

2013-09-01

169

Improvement of the sensitivity of opto-acoustic trace gas analysis by condensation  

SciTech Connect

It is suggested that the minimum detectable concentration of a trace gas in an optoacoustically monitored sample of air could be decreased by five orders of magnitude by condensing the sample and optoacoustically monitoring the liquid phase.

Slatkine, M.

1981-01-01

170

Non-Condensible Gas Fraction Predictions Using Wet and Dry Bulb Temperature Measurements.  

National Technical Information Service (NTIS)

A technique is presented whereby non-condensible gas mass fractions in a closed system can be determined using wet bulb and dry bulb temperature and system pressure measurements. This technique would have application in situations where sampling technique...

J. K. Bowman P. Griffith

1983-01-01

171

Kinetic Theory of a Spin-1 Bose Condensed Gas at Finite Temperatures  

NASA Astrophysics Data System (ADS)

We derive a kinetic theory of a spin-1 Bose condensed gas at finite temperatures. The theory consists of coupled equations for the condensate and noncondensate. The condensate dynamics is described by a generalized Gross-Pitaevskii (GP) equation including the spin degree of freedom. The condensate and noncondensate atoms interact with each other through the mean field and collisions. From the coupled equations, we determine the condition for static equilibrium of the spin-1 system. We also use the static thermal cloud approximation to derive a generalized GP equation including a dissipative term due to the coupling to a thermal cloud.

Endo, Yuki; Nikuni, Tetsuro

2011-05-01

172

Model Predicts Two-Phase Flow Pressure Drop in Gas-Condensate Transmission Lines  

Microsoft Academic Search

The prediction of two-phase flow pressure drop in the gas-condensate pipelines is a challenge for optimal design of such pipelines. This article is an attempt to study the applicability of Taitel and Dukler work (with the combination of appropriate friction factor correlations) for the modeling of gas-condensate flow transmission systems. Comparison of the results from the proposed approach with other

S. Mokhatab; M. Bonizzi

2007-01-01

173

Experimental and analytical study of the effects of noncondensable gas in a passive condenser system  

NASA Astrophysics Data System (ADS)

Passive Containment Cooling System (PCCS) of the Simplified Boiling Water Reactor (SBWR) is a passive condenser system which is designed to remove energy from the reactor containment during a postulated reactor accident. The presence of noncondensable gas in the vapor can greatly reduce the performance of condensers. Hence a detailed knowledge of the heat removal performance of the PCCS in the presence of noncondensable gas is crucial for the safety and design optimization of the SBWR. The purpose of the present study is the experimental and theoretical investigation of the effects of noncondensable gas in a passive condenser system. Condensation experiments were performed for a vertical tube submerged in water pool. The present experimental data provide a new database for complete condensation, cyclic venting and through flow modes of the passive condenser. Cyclic venting mode was simulated by a control volume analysis. Analysis results showed that venting period decreases with noncondensable gas fraction. It was found that inception of venting can occur before the condenser is fully filled with noncondensable gas. A boundary layer model was developed for the prediction of the film condensation with noncondensable gas in a vertical tube. Full set of the governing equations for the liquid film and vapor-gas mixture regions were solved. A heat and mass analogy model was also developed with a specific purpose for use in the thermal hydraulic system analysis code. In the vapor-gas mixture region, general momentum, heat and mass transport relations derived by analytic method were used with the consideration of surface suction effect. The predictions from the models were compared with the experimental data and the agreement was satisfactory. A mechanistic condensation correlation was developed based on the experimental data and the analysis results. It contains all the heat transfer components in its functional relationships. New correlation can provide accurate estimation of local condensation heat transfer coefficient for wide range of operating parameters. The assessment of wall condensation models in RELAP5 code was performed. Experimental conditions were simulated with RELAP5. Code simulation showed quite different results compared with data. Therefore, the condensation model in RELAP5 needs to be improved.

Oh, Seungmin

174

Metal-semiconductor and condensed gas-semiconductor interface formation  

NASA Astrophysics Data System (ADS)

Two adatom/III-V semiconductor interfaces were examined with high resolution synchrotron radiation photoemission spectroscopy. An investigation of a metal-semiconductor interface, Al/GaAs(110), was performed as a function of substrate temperature to correlate the evolving interfacial chemistry and morphology with band bending. Detailed examination shows a separation in energy of approximately 1.0 eV for the Al 2p binding energy for n- and p-type GaAs at submonolayer coverages. This equals the difference in band bending for the two substrates, demonstrating that the adatom energy reference is an intrinsic level of the semiconductor, not the Fermi level. Substrate band bending approaches its final value when E(sub f) becomes the energy reference for the overlayer, and this occurs at the onset of metallic overlayer behavior. The overlayer morphology, disrupted atom distribution, and band bending depends on the substrate temperature, while the amount of substrate disruption and the final value of E(sub f) in the gap at high coverage does not. Temperature-dependent band bending observed below a monolayer can be understood by considering the importance of a surface photovoltage. Studies of a condensed gas-semiconductor interface, O2/GaAs(110), were conducted at 20 K to examine the dynamics of photo-induced oxidation. Detailed core level analysis of photon exposure-dependent data demonstrate that As(+1)- and As(+3)-like bonding configurations form in a step-wise fashion with approximately equal reaction probabilities for the two steps. The high sticking coefficient for O2 at 20 K makes it possible to locally oxide the surface ten orders of magnitude more efficiently than in equivalent experiments at 300 K. Reaction cross sections determined from modeling the dynamics of the reaction processes indicate that an oxidation mechanism involving secondary electrons is operative. Results are also presented for the competition between continued reaction and photon-induced oxygen desorption, where desorption occurres via a first order process.

Anderson, Steven Gene

1990-06-01

175

Pair condensation in a dilute Bose gas with Rashba spin–orbit coupling  

NASA Astrophysics Data System (ADS)

We show that in a two-component Bose gas with Rashba spin–orbit coupling (SOC), two atoms can form bound states (Rashbons) with any intra-species scattering length. At zero center-of-mass momentum, there are two degenerate Rashbons due to time-reversal symmetry, but the degeneracy is lifted at finite in-plane momentum with two different effective masses. A stable Rashbon condensation can be created in a dilute Bose gas with attractive intra-species and repulsive inter-species interactions. The critical temperature of Rashbon condensation is about six times smaller than the Bose–Einstein condensation transition temperature of an ideal Bose gas. Due to the Rashba SOC, excitations in the Rashbon condensation phase are anisotropic in momentum space.

Li, Rong; Yin, Lan

2014-05-01

176

Fluid-dynamical and poro-elastic coupling of gas permeability of inert and sorbing gases on an Australian sub-bituminous coal  

NASA Astrophysics Data System (ADS)

The interaction and the coupling of slip-flow, a fluid dynamic phenomenon, and the cleat volume compressibility which is a poroelastic phenomenon has been investigated on two samples from the Taroom coal measure, Surat Basin, Queensland Australia. Measurements were performed using inert (helium and argon) and sorbing gases (nitrogen, methane and carbon dioxide) at controlled effective stress. We observed the following regular sequence of permeability coefficients for the different gases: Helium >> argon => nitrogen > methane >> CO2 Even after slip-flow correction, different intrinsic permeability coefficients are obtained for the same sample if different gases are used in the tests. The permeability values determined with helium are largest while those measured with CO2 are lowest. Inert gases like helium and argon show higher apparent- and even slip flow-corrected permeability coefficients than sorbing gases like methane or carbon dioxide. This observation is contrary to the prediction that the slip-flow corrected permeability have to be the same for all gases. The cleat volume compressibility cf was evaluated using the 'matchstick approach' [1, 2]. The cleat volume compressibility coefficients cf are almost identical for the two samples taken from the same well. However, for one sample a strong dependence of the cf with the mean pore pressure was observed. This is attributed to a strong slip-flow effect caused by a narrow cleat system as compared to the sister sample. The cleat volume compressibility coefficient cf is almost the same for inert and sorbing gases. We conclude that the occurrence of slip-flow in coals is able to compensate the permeability reduction resulting from increasing effective stress. This should lead to a much higher productivity of coal bed methane reservoirs in the third production phase (pseudo-steady state phase; [3]). This conclusion appears to be also valid for shale gas and tight gas reservoirs, where the gas transport takes place in meso- and micropores, as well.

Gensterblum, Y.; Krooss, B. M.

2013-12-01

177

Stability and Oxidation Resistance of Iron- and Cobalt-Based Magnetic Nanoparticle Fluids Fabricated by Inert-Gas Condensation.  

National Technical Information Service (NTIS)

Magnetic nanoparticle fluids have numerous biomedical applications, including magnetic imaging, drug delivery, and hyperthermia treatment for cancer. Ideal magnetic nanoparticle fluids have well-separated, biocompatible nanoparticles with a small size dis...

M. A. Strand, N. H. Hai, R. Lemoine, S. Remboldt, S. Wignall

2005-01-01

178

Semiconducting Electrodes for Determination of Sulfur Compounds in Gas Condensates  

Microsoft Academic Search

New electrodes with semiconducting membranes distinguished by elevated chemical resistance in aggressive media, mechanical strength, and a long lifetime are proposed as indicator electrodes. A method is developed for successive potentiometric determination of mercaptans and sulfides from one sample of condensate using an indicator pair consisting of semiconducting and platinum electrodes. The method is characterized by accuracy, speed, and reliability.

V. A. Burakhta

2002-01-01

179

Some effects of non-condensible gas in geothermal reservoirs with steam-water counterflow  

SciTech Connect

A mathematical model is developed for fluid and heat flow in two-phase geothermal reservoirs containing non-condensible gas (CO{sub 2}). Vertical profiles of temperature, pressures and phase saturations in steady-state conditions are obtained by numerically integrating the coupled ordinary differential equations describing conservation of water, CO{sub 2}, and energy. Solutions including binary diffusion effects in the gas phase are generated for cases with net mass throughflow as well as for balanced liquid-vapor counterflow. Calculated examples illustrate some fundamental characteristics of two-phase heat transmission systems with non-condensible gas. 14 refs., 3 figs.

McKibbin, R.; Pruess, K.

1988-01-01

180

Some effects of non-condensible gas in geothermal reservoirs with steam-water counterflow  

SciTech Connect

A mathematical model is developed for fluid and heat flow in two-phase geothermal reservoirs containing non-condensible gas (CO{sub 2}). Vertical profiles of temperature, pressures and phase saturations in steady-state conditions are obtained by numerically integrating the coupled ordinary differential equations describing conservation of water, CO{sub 2}, and energy. Solutions including binary diffusion effects in the gas phase are generated for cases with net mass throughflow as well as for balanced liquid-vapor counterflow. Calculated examples illustrate some fundamental characteristics of two-phase heat transmission systems with non-condensible gas.

McKibbin, Robert; Pruess, Karsten

1988-01-01

181

Intrinsic bioremediation of petroleum hydrocarbons in a gas condensate-contaminated aquifer  

Microsoft Academic Search

A study was designed to determine if the intrinsic bioremediation of gas condensate hydrocarbons represented an important fate process in a shallow aquifer underlying a natural gas production site. For over 4 yr, changes in the groundwater, sediment, and vadose zone chemistry in the contaminated portion of the aquifer were interpreted relative to a background zone. Changes included decreased dissolved

Lisa M. Gieg; R. S. Tanner; S. H. Jr. Harris; K. L. Sublette; J. M. Suflita; R. V. Kolhatkar

1999-01-01

182

One-step synthesis of MoO3 and MoO3-x nanostructures by condensation in gas: effect of the carrier gas.  

PubMed

MoO3 and MoO3-x nanostructures were grown in a simple one-step process by direct evaporation of MoO3 pellets from a tungsten resistive source in presence of helium or hydrogen at pressures from 100 to 1200 Pa. This method uses no templates, catalysts or oxidizing agents. It leads to one dimensional (1-D) crystalline nanostructures mixed with amorphous material in variable ratios. Amorphous structures grew preferentially when hydrogen was used as carrier gas while crystalline material predominated when helium was used. In fact, only crystalline structures were found when the evaporation was carried out under a helium pressure of 600 Pa with source temperatures between 763 and 910 degrees C. Hydrated MoO3 phases with different water concentrations were preferentially formed using hydrogen. X-ray photoelectron spectroscopy detected only molybdenum in its +6 oxidation state in the samples grown under helium, exhibiting the same chemical composition of the source material. Molybdenum in its +6 as well as its +5 oxidation states was detected in the samples obtained under hydrogen at 600 Pa. Hydroxyl groups were identified in samples grown using both gases. The effect of the helium pressure on the growth kinetics and crystallinity of the samples is discussed according to the kinetics conditions (supersaturation, evaporation, cooling and convection rates) driving to the formation of nanostructures in the inert-gas condensation. Finally, the effect of hydrogen on the growth of MoO3 is discussed. PMID:21137784

Diaz-Droguett, D E; Fuenzalida, V M

2010-10-01

183

Spinor condensate of {sup 87}Rb as a dipolar gas  

SciTech Connect

We consider a spinor condensate of {sup 87}Rb atoms in the F=1 hyperfine state confined in an optical dipole trap. Putting initially all atoms in the m{sub F}=0 component, we find that the system evolves toward a state of thermal equilibrium with kinetic energy equally distributed among all magnetic components. We show that this process is dominated by the dipolar interaction of magnetic spins rather than spin-mixing contact potential. Our results show that because of a dynamical separation of magnetic components, the spin-mixing dynamics in the {sup 87}Rb condensate is governed by the dipolar interaction which plays no role in a single-component rubidium system in a magnetic trap.

Swislocki, Tomasz; Gajda, Mariusz [Instytut Fizyki PAN, Al.Lotnikow 32/46, PL-02-668 Warsaw (Poland); Brewczyk, Miroslaw [Wydzial Fizyki, Uniwersytet w Bialymstoku, ul. Lipowa 41, PL-15-424 Bialystok (Poland); RzaPzewski, Kazimierz [Wydzial Matematyczno-Przyrodniczy SNS UKSW, ul. Dewajtis 5, PL-01-815 Warsaw (Poland); Centrum Fizyki Teoretycznej PAN, Al.Lotnikow 32/46, PL-02-668 Warsaw (Poland)

2010-03-15

184

Kinetic limit of the ethane and ethylene yield in the gas phase condensation of methane  

SciTech Connect

A kinetic simulation of the initiated oxidative condensation of methane in the gas phase showed that the additional generation of methyl radicals via the reaction CH{sub 4} + O{sub 2} {yields} CH{sub 3} + HO{sub 2} causes a nearly tenfold increase in the C{sub 2} hydrocarbon yield. However, a kinetic limit of the yield exists that is close to that determined in experiments on the catalytic oxidative condensation of methane.

Vedeneev, V.I.; Arutyunov, V.S.; Basevich, V.Ya. [N.N. Semenov Institute of Chemical Physics, Moscow (Russian Federation)

1995-08-01

185

Theory of Critical Temperature Adiabatic Change for Ideal Gas Bose-Einstein Condensation in Optical Lattices  

Microsoft Academic Search

We present a scheme of analytical calculations determining the critical\\u000atemperature and the number of condensed atoms of ideal gas Bose-Einstein\\u000acondensation in external potentials with 1D, 2D or 3D periodicity. In\\u000aparticular we show that the width of the lowest energy band appears as the main\\u000aparameter determining the critical temperature of condensation. Is obtained a\\u000avery simple, proportional

G. A. Muradyan; A. Zh

2006-01-01

186

Economics of Condensing Gas Furnaces and Water Heaters Potential in Residential Single Family Homes  

SciTech Connect

Residential space and water heating accounts for over 90percent of total residential primary gas consumption in the United States. Condensing space and water heating equipment are 10-30percent more energy-efficient than conventional space and water heating. Currently, condensing gas furnaces represent 40 percent of shipments and are common in the Northern U.S. market. Meanwhile, manufacturers are planning to develop condensing gas storage water heaters to qualify for Energy Star? certification. Consumers, installers, and builders who make decisions about installing space and water heating equipment generally do not perform an analysis to assess the economic impacts of different combinations and efficiencies of space and water heating equipment. Thus, equipment is often installed without taking into consideration the potential life-cycle economic and energy savings of installing space and water heating equipment combinations. Drawing on previous and current analysis conducted for the United States Department of Energy rulemaking on amended standards for furnaces and water heaters, this paper evaluates the extent to which condensing equipment can provide life-cycle cost-effectiveness in a representative sample of single family American homes. The economic analyses indicate that significant energy savings and consumer benefits may result from large-scale introduction of condensing water heaters combined with condensing furnaces in U.S. residential single-family housing, particularly in the Northern region. The analyses also shows that important benefits may be overlooked when policy analysts evaluate the impact of space and water heating equipment separately.

Lekov, Alex; Franco, Victor; Meyers, Steve

2010-05-14

187

Recovery of Water from Boiler Flue Gas Using Condensing Heat Exchangers  

SciTech Connect

Most of the water used in a thermoelectric power plant is used for cooling, and DOE has been focusing on possible techniques to reduce the amount of fresh water needed for cooling. DOE has also been placing emphasis on recovery of usable water from sources not generally considered, such as mine water, water produced from oil and gas extraction, and water contained in boiler flue gas. This report deals with development of condensing heat exchanger technology for recovering moisture from flue gas from coal-fired power plants. The report describes: (1) An expanded data base on water and acid condensation characteristics of condensing heat exchangers in coal-fired units. This data base was generated by performing slip stream tests at a power plant with high sulfur bituminous coal and a wet FGD scrubber and at a power plant firing high-moisture, low rank coals. (2) Data on typical concentrations of HCl, HNO{sub 3} and H{sub 2}SO{sub 4} in low temperature condensed flue gas moisture, and mercury capture efficiencies as functions of process conditions in power plant field tests. (3) Theoretical predictions for sulfuric acid concentrations on tube surfaces at temperatures above the water vapor dewpoint temperature and below the sulfuric acid dew point temperature. (4) Data on corrosion rates of candidate heat exchanger tube materials for the different regions of the heat exchanger system as functions of acid concentration and temperature. (5) Data on effectiveness of acid traps in reducing sulfuric acid concentrations in a heat exchanger tube bundle. (6) Condensed flue gas water treatment needs and costs. (7) Condensing heat exchanger designs and installed capital costs for full-scale applications, both for installation immediately downstream of an ESP or baghouse and for installation downstream of a wet SO{sub 2} scrubber. (8) Results of cost-benefit studies of condensing heat exchangers.

Edward Levy; Harun Bilirgen; John DuPoint

2011-03-31

188

Recovery of Water from Boiler Flue Gas Using Condensing Heat Exchangers  

SciTech Connect

Most of the water used in a thermoelectric power plant is used for cooling, and DOE has been focusing on possible techniques to reduce the amount of fresh water needed for cooling. DOE has also been placing emphasis on recovery of usable water from sources not generally considered, such as mine water, water produced from oil and gas extraction, and water contained in boiler flue gas. This report deals with development of condensing heat exchanger technology for recovering moisture from flue gas from coal-fired power plants. The report describes: • An expanded data base on water and acid condensation characteristics of condensing heat exchangers in coal-fired units. This data base was generated by performing slip stream tests at a power plant with high sulfur bituminous coal and a wet FGD scrubber and at a power plant firing highmoisture, low rank coals. • Data on typical concentrations of HCl, HNO{sub 3} and H{sub 2}SO{sub 4} in low temperature condensed flue gas moisture, and mercury capture efficiencies as functions of process conditions in power plant field tests. • Theoretical predictions for sulfuric acid concentrations on tube surfaces at temperatures above the water vapor dewpoint temperature and below the sulfuric acid dew point temperature. • Data on corrosion rates of candidate heat exchanger tube materials for the different regions of the heat exchanger system as functions of acid concentration and temperature. • Data on effectiveness of acid traps in reducing sulfuric acid concentrations in a heat exchanger tube bundle. • Condensed flue gas water treatment needs and costs. • Condensing heat exchanger designs and installed capital costs for full-scale applications, both for installation immediately downstream of an ESP or baghouse and for installation downstream of a wet SO{sub 2} scrubber. • Results of cost-benefit studies of condensing heat exchangers.

Levy, Edward; Bilirgen, Harun; DuPont, John

2011-03-31

189

On the retrograde condensation behavior of lean natural gas  

NASA Astrophysics Data System (ADS)

The occurrence of liquid dropout in natural gas pipelines may cause operational problems during storage, transport, and processing. Therefore, the availability of a model that accurately predicts the amount of liquid formed is of great importance for the natural gas industry. The objective of this study is to develop a thermodynamic model for the accurate prediction of the amount of liquid formed in natural gas pipelines at transportation conditions. As input, the model requires an accurate gas analysis. A modified Peng-Robinson equation of state was selected for the phase equilibrium calculations. Interaction parameters were optimized from experimental data at conditions of practical interest, i.e., at pressures 10 < p < 70 bar and at temperatures 250 < T < 290 K. For a number of “keysystems,” the interaction parameters were calculated from new accurate solubility data of heavy hydrocarbons in some of the main constituents of natural gas like methane and nitrogen. Also, an extensive experimental program was carried out to study the influence of minute amounts of nitrogen, ethane and carbon dioxide in methane on the solubility behavior of decane in these gas mixtures. From a sensitivity analysis, it could be concluded that the liquid dropout is influenced mainly by the concentration and characterization of C7-C13 fractions. In this work, two characterization procedures to represent these fractions are compared. For two types of lean natural gas, the model predictions are compared with field measurement data, recently supplied by the Dutch natural gas industry.

Voulgaris, M. E.; Peters, C. J.; de Swaan Arons, J.

1995-05-01

190

On the retrograde condensation behavior of lean natural gas  

SciTech Connect

The occurrence of liquid dropout in natural gas pipelines may cause operational problems during storage, transport, and processing. Therefore, the availability of a model that accurately predicts the amount of liquid formed is of grate importance for the natural gas industry. The objective of this study is to develop a thermodynamic model for the accurate prediction of the amount of liquid formed in natural gas pipelines at transportation conditions. As input, the model requires an accurate gas analysis. A modified Peng-Robinson equation of state was selected for the phase equilibrium calculations. Interaction parameters were optimized from experimental data at conditions of practical interest, i.e., at pressures 10gas like methane and nitrogen. Also, an extensive experimental program was carried out to study the influence of minute amounts of nitrogen, ethane and carbon dioxide in methane on the solubility behavior of decane in these gas mixtures. From a sensitivity analysis, it could be concluded that the liquid dropout is influenced mainly by the concentration and characterization of C{sub 7}-C{sub 13} fractions. In this work, two characterization procedures to represent these fractions are compared. For two types of lean natural gas, the model predictions are compared with field measurement data, recently supplied by the Dutch natural gas industry.

Voulgaris, M.E.; Peters, C.J.; Arons, J. Swaan de [Univ. of Technology, Julianalaan (Netherlands)

1995-05-01

191

Real gas effects 2: Influence of condensation on minimum operating temperatures of cryogenic wind tunnels  

NASA Technical Reports Server (NTRS)

Condensation effects are responsible for the minimum operating temperatures of cryogenic wind tunnels at total pressures up to about 9 atmospheres. The two primary modes of condensation homogeneous nucleation and heterogeneous nucleation and the conditions with which either may limit minimum operating temperatures are reveiwed. Previous hypersonic and supersonic condensation data are reviewed as are data taken in the nitrogen gas, Langley 0.3 Meter Transonic Cryogenic Tunnel. Analysis of data in the 0.3 m tunnel suggests that the onset of homogenous nucleation may be approximated by an analysis by sivier and that the onset of heterogeneous nucleation is only apparent just below free stream saturation. Extension of the results from the 0.3 m tunnel to other nitrogen gas cryogenic tunnels is discussed and is shown to depend on length scales, purity of the liquid nitrogen injected for cooling, number of particulates in the flow, and the extent to which the injected liquid nitrogen is evaporated.

Hall, R. M.

1980-01-01

192

Effect of Inert Gas Additive Species on Cl(2) High Density Plasma Etching of Compound Semiconductors: Part 1. GaAs and GaSb  

SciTech Connect

The role of the inert gas additive (He, Ar, Xe) to C12 Inductively Coupled Plasmas for dry etching of GaAs and GaSb was examined through the effect on etch rate, surface roughness and near-surface stoichiometry. The etch rates for both materials go through a maximum with Clz 0/0 in each type of discharge (C12/'He, C12/Ar, C12/Xc), reflecting the need to have efficient ion-assisted resorption of the etch products. Etch yields initially increase strongly with source power as the chlorine neutral density increases, but decrease again at high powers as the etching becomes reactant-limited. The etched surfaces are generally smoother with Ax or Xe addition, and maintain their stoichiometry.

Abernathy, C.R.; Cho, H.; Hahn, Y.B.; Hays, D.C.; Jung, K.B.; Pearton, S.J.; Shul, R.J.

1998-12-23

193

Wide-band exciplex halogen lamps operating on inert gas mixtures with chlorine and Freon-12 molecules  

NASA Astrophysics Data System (ADS)

The results of analysis of the spectral characteristics of short-wave radiation sources operating on transitions in argon, krypton, and xenon monohalogenides, as well as chlorine molecules, excited by a longitudinal low-pressure glow discharge are considered. Radiation emitted by ArCl*, KrCl*, XeCl*, Cl{2/**}, and Cl{2/*} molecules in a spectral range of 170-350 nm is optimized using complex working mixtures of Ar-Kr-(Xe)-Cl2 in the lamps. The average radiation power of the lamps ranges from 1 to 10 W for an efficiency of ?25%. Optimization of wide-band lamps on transitions in chlorine molecules and the decay products of Freon-12 molecules (CF2Cl2) is carried out on mixtures of helium with chlorine and Freon-12 molecules. This makes it possible to develop lamps emitting in a spectral range of 140-270 nm and containing no costly inert gases (Xe or Kr) in their working mixtures. Exciplex halogen lamps with a wide-band emission spectrum in the VUV-UV range can be used in spectrometers as radiation sources in experiments with absorption and in high-energy chemistry, ecology, and medicine.

Shuaibov, A. K.; Shevera, I. V.

2007-09-01

194

Preparation of gas hydrates by nonequilibrium condensation of molecular beams  

NASA Astrophysics Data System (ADS)

Layers of amorphous ice saturated with carbon dioxide were prepared by the deposition of molecular beams of water and gas onto a substrate cooled with liquid nitrogen. Their heating is accompanied by glass transition (softening) and subsequent spontaneous crystallization. The glass transition and crystallization temperatures were determined from the change in dielectric properties during heating. The heat effects of the transformations were detected using differential thermal analysis. The crystallization of amorphous layers under conditions of deep metastability leads to the formation of crystalline hydrates. The avalanche nucleation of crystallization sites captures the gas molecules; therefore, they are not displaced by the movement of the crystallization front.

Faizullin, M. Z.; Vinogradov, A. V.; Koverda, V. P.

2013-09-01

195

Femtosecond spectroscopy of cluster anions: insights into condensed-phase phenomena from the gas-phase.  

PubMed

Ultrafast spectroscopy allows chemical and physical processes to be observed on time-scales faster than the nuclear motion within molecules. This tutorial review explores how such experiments, and specifically time-resolved photoelectron spectroscopy on gas-phase cluster anions, provide a molecular-level understanding of the processes that are normally associated with condensed-phase dynamics. PMID:18224260

Verlet, Jan R R

2008-03-01

196

The frequency response of large-amplitude oscillations of a trapped Bose condensed gas  

Microsoft Academic Search

We study the frequency response of large-amplitude oscillations of a trapped Bose condensed gas. On the basis of the Thomas-Fermi approximation, we deduce the hydrodynamical equation including the excitation source of the velocity drive, and obtain the analytical expression for the frequency as a function of velocity fluctuation amplitude, trap geometry, and symmetry of modes. By solving the expansion equation

Yong-li Ma; Siu-Tat Chui

2002-01-01

197

Gasification and Ignition of a Condensed Fuel by a Hot Stagnant Gas.  

National Technical Information Service (NTIS)

Asymptotic techniques based on the limit of high activation energy have been used to analyze the ignition process of a condensed fuel suddenly exposed to a hot stagnant gas. Several cases are studied differing in the location of the exothermic ignition re...

M. Kindelan A. Linan

1977-01-01

198

Gas phase aldol condensation of lower aldehydes over clinoptilolite rich natural zeolites  

Microsoft Academic Search

Catalytic materials prepared from natural clinoptilolite by ion exchange and acid treatment have been successfully used in the gas phase conversion of acetaldehyde and formaldehyde into acrolein. The modifications made on the raw clinoptilolite have generated important changes of the texture and catalytic sites. The results in catalysis showed that the nature and the amount of condensation products strongly depend

Claudia Cobzaru; Spiridon Oprea; Emil Dumitriu; Vasile Hulea

2008-01-01

199

Mathematical Simulation of Natural Gas Condensation Processes Using the Peng-Robinson Equation of State  

Microsoft Academic Search

On the basis of its simplicity and the data obtained by a great number of tests and comparative analysis, the authors consider the Peng-Robinson (PR) equation of state to be the most suitable to calculate the condensation processes of natural gas, and further on to set up the equations of material and heat balances. In case of mixtures, the accuracy

Zoltan Nagy; Arkadiy Shirkovskiy

1982-01-01

200

Role of gas- and condensed-phase kinetics in burning rate control of energetic solids  

Microsoft Academic Search

A simplified two-step kinetics model for the combustion of energetic solids has been used to investigate the effect of gas-phase activation energy on flame structure and burning rate and the role of gas- versus condensed-phase kinetics in determining burning rate. The following assumptions are made: a single-step, unimolecular, high activation energy decomposition process which is overall relatively energetically neutral, is

M. J. Ward; S. F. Son; M. Q. Brewster

1998-01-01

201

Inert electrode connection  

DOEpatents

An inert electrode connection is disclosed wherein a layer of inert electrode material is bonded to a layer of conductive material by providing at least one intermediate layer of material therebetween comprising a predetermined ratio of inert material to conductive material. In a preferred embodiment, the connection is formed by placing in a die a layer of powdered inert material, at least one layer of a mixture of powdered inert material and conductive material, and a layer of powdered conductive material. The connection is then formed by pressing the material at 15,000-20,000 psi to form a powder compact and then densifying the powder compact in an inert or reducing atmosphere at a temperature of 1200.degree.-1500.degree. C.

Weyand, John D. (Greensburg, PA); Woods, Robert W. (New Kensington, PA); DeYoung, David H. (Plum Boro, PA); Ray, Siba P. (Plum Boro, PA)

1985-01-01

202

Inert electrode connection  

DOEpatents

An inert electrode connection is disclosed wherein a layer of inert electrode material is bonded to a layer of conductive material by providing at least one intermediate layer of material therebetween comprising a predetermined ratio of inert material to conductive material. In a preferred embodiment, the connection is formed by placing in a die a layer of powdered inert material, at least one layer of a mixture of powdered inert material and conductive material, and a layer of powdered conductive material. The connection is then formed by pressing the material at 15,000--20,000 psi to form a powder compact and then densifying the powder compact in an inert or reducing atmosphere at a temperature of 1,200--1,500 C. 5 figs.

Weyand, J.D.; Woods, R.W.; DeYoung, D.H.; Ray, S.P.

1985-02-19

203

Application of the parallel multicanonical method to lattice gas condensation  

NASA Astrophysics Data System (ADS)

We present the speedup from a novel parallel implementation of the multicanonical method on the example of a lattice gas in two and three dimensions. In this approach, all cores perform independent equilibrium runs with identical weights, collecting their sampled histograms after each iteration in order to estimate consecutive weights. The weights are then redistributed to all cores. These steps are repeated until the weights are converged. This procedure benefits from a minimum of communication while distributing the necessary amount of statistics efficiently. Using this method allows us to study a broad temperature range for a variety of large and complex systems. Here, a gas is modeled as particles on the lattice, which interact only with their nearest neighbors. For a fixed density this model is equivalent to the Ising model with fixed magnetization. We compare our results to an analytic prediction for equilibrium droplet formation, confirming that a single macroscopic droplet forms only above a critical density.

Zierenberg, Johannes; Wiedenmann, Micha; Janke, Wolfhard

2014-05-01

204

Numerical Simulation of Stationary AC Tungsten Inert Gas Welding of Aluminum Plate in Consideration of Oxide Layer Cleaning  

NASA Astrophysics Data System (ADS)

An unified numerical simulation model of AC TIG welding of the aluminum plate considering energy balance among the electrode, the arc and the base metal and employing an analytical model for calculating cleaning rate of the oxide layer has been developed for investigating heat transport properties and weld pool formation process in AC TIG welding of aluminum plate. As a result of this simulation, it was shown that although the heat flux from the arc onto the base metal increases in EN (Electrode Negative) phase due to the electron condensation, that in EP (Electrode Positive) phase conversely decreases because mainly of cooling caused by the electron emission. Furthermore, the validity of the simulation model was confirmed by comparing to experimental results such as the arc voltage, the area of cleaning zone and the shape of weld pool.

Tashiro, Shinichi; Tanaka, Manabu

205

Microemulsion Prepared Pt in Ceria: Catalytically Active for Water Gas Shift Reaction but Totally Inert for Methanation  

Microsoft Academic Search

A core–shell Pt in ceria type of catalyst prepared by a microemulsion technique shows high activity for both water gas shift\\u000a and reverse water gas shift reactions but it does not catalyze methanation from carbon oxides and hydrogen feeds at all, whereas\\u000a Pt-ceria catalysts prepared by traditional methods are effective for all these reactions under comparable reaction conditions.\\u000a This clearly

Connie Mei Yu Yeung; Shik Chi Tsang

2009-01-01

206

Exciton gas compression and metallic condensation in a single semiconductor quantum wire.  

PubMed

We study the metal-insulator transition in individual self-assembled quantum wires and report optical evidence of metallic liquid condensation at low temperatures. First, we observe that the temperature and power dependence of the single nanowire photoluminescence follow the evolution expected for an electron-hole liquid in one dimension. Second, we find novel spectral features that suggest that in this situation the expanding liquid condensate compresses the exciton gas in real space. Finally, we estimate the critical density and critical temperature of the phase transition diagram at n{c} approximately 1 x 10;{5} cm;{-1} and T{c} approximately 35 K, respectively. PMID:18764504

Alén, B; Fuster, D; Muńoz-Matutano, G; Martķnez-Pastor, J; Gonzįlez, Y; Canet-Ferrer, J; Gonzįlez, L

2008-08-01

207

Evolution of non-condensable gas in ammonia heat pipes  

NASA Technical Reports Server (NTRS)

Accumulation of noncondensible gas (NCG) has been observed in ammonia heat pipes. NCG has been found to be detrimental to the performance of heat pipes and can result in complete operational failure. A kinetic and thermodynamic analysis has been performed that evaluates the dissociation of ammonia under various conditions and predicts the amount of NCG present in heat pipes. The analysis indicates that the observed NCG in ammonia heat pipes can be attributed to the dissociation of ammonia into its constituents, hydrogen and nitrogen. It shows time and temperature to be the important parameters, in conjunction with the catalytic characteristic of the container material.

Richter, Robert

1990-01-01

208

Response of electrochemical oxygen sensors to inert gas-air and carbon dioxide-air mixtures: measurements and mathematical modelling.  

PubMed

Electrochemical oxygen gas sensors are widely used for monitoring the state of inertisation of flammable atmospheres and to warn of asphyxiation risks. It is well established but not widely known by users of such oxygen sensors that the response of the sensor is affected by the nature of the diluent gas responsible for the decrease in ambient oxygen concentration. The present work investigates the response of electrochemical sensors, with either acid or alkaline electrolytes, to gas mixtures comprising air with enhanced levels of nitrogen, carbon dioxide, argon or helium. The measurements indicate that both types of sensors over-read the oxygen concentrations when atmospheres contain high levels of helium. Sensors with alkaline electrolytes are also shown to underestimate the severity of the hazard in atmospheres containing high levels of carbon dioxide. This deviation is greater for alkaline electrolyte sensors compared to acid electrolyte sensors. A Computational Fluid Dynamics (CFD) model is developed to predict the response of an alkaline electrolyte, electrochemical gas sensor. Differences between predicted and measured sensor responses are less than 10% in relative terms for nearly all of the gas mixtures tested, and in many cases less than 5%. Extending the model to simulate responses of sensors with acid electrolytes would be straightforward. PMID:21112151

Walsh, P T; Gant, S E; Dowker, K P; Batt, R

2011-02-15

209

Terahertz Active Photonic Crystals for Condensed Gas Sensing  

PubMed Central

The terahertz (THz) spectral region, covering frequencies from 1 to 10 THz, is highly interesting for chemical sensing. The energy of rotational and vibrational transitions of molecules lies within this frequency range. Therefore, chemical fingerprints can be derived, allowing for a simple detection scheme. Here, we present an optical sensor based on active photonic crystals (PhCs), i.e., the pillars are fabricated directly from an active THz quantum-cascade laser medium. The individual pillars are pumped electrically leading to laser emission at cryogenic temperatures. There is no need to couple light into the resonant structure because the PhC itself is used as the light source. An injected gas changes the resonance condition of the PhC and thereby the laser emission frequency. We achieve an experimental frequency shift of 10?3 times the center lasing frequency. The minimum detectable refractive index change is 1.6 × 10?5 RIU.

Benz, Alexander; Deutsch, Christoph; Brandstetter, Martin; Andrews, Aaron M.; Klang, Pavel; Detz, Hermann; Schrenk, Werner; Strasser, Gottfried; Unterrainer, Karl

2011-01-01

210

Transformation of a beta gamma Hot-Cell under Air in a Tight Hot-Cell under Inert Gas.  

National Technical Information Service (NTIS)

For several years now, fuel elements from graphite gas reactors have been stored in pools at the Cadarache Center after having been subjected (in general) to laboratory examinations. The CEA has adopted the following re-transfer procedure for these fuel e...

G. Lambert

1981-01-01

211

Laws of the DC arc in an inert gas during melting in furnaces with a tungsten electrode  

NASA Astrophysics Data System (ADS)

The I-V and voltage-baric characteristics of the dc arc glowing in argon between a tungsten cathode and a molten anode made of titanium, chromium, or manganese are studied at various gas pressures, arc currents, and arc lengths. The arc is probed to establish the relation between the voltage drop across the arc and its regions on the anode material and the melting conditions.

Belyanchikov, L. N.

2012-06-01

212

Ongoing Galactic Accretion: Simulations and Observations of Condensed Gas in Hot Halos  

NASA Astrophysics Data System (ADS)

Ongoing accretion onto galactic disks has been recently theorized to progress via the unstable cooling of the baryonic halo into condensed clouds. These clouds have been identified as analogous to the high-velocity clouds (HVCs) observed in H I in our Galaxy. Here we compare the distribution of HVCs observed around our own Galaxy and extraplanar gas around the Andromeda galaxy to these possible HVC analogs in a simulation of galaxy formation that naturally generates these condensed clouds. We find a very good correspondence between these observations and the simulation in terms of number, angular size, velocity distribution, overall flux, and flux distribution of the clouds. We show that condensed cloud accretion accounts for only ~0.2 Msolar yr-1 of the current overall Galactic accretion in the simulations. We also find that the simulated halo clouds accelerate and become more massive as they fall toward the disk. The parameter space of the simulated clouds is consistent with all of the observed HVC complexes that have distance constraints, except the Magellanic Stream, which is known to have a different origin. We also find that nearly half of these simulated halo clouds would be indistinguishable from lower velocity gas and that this effect is strongest farther from the disk of the galaxy, thus indicating a possible missing population of HVCs. These results indicate that the majority of HVCs are consistent with being infalling, condensed clouds that are a remnant of Galaxy formation.

Peek, J. E. G.; Putman, M. E.; Sommer-Larsen, Jesper

2008-02-01

213

Study of materials to resist corrosion in condensing gas fired furnaces  

NASA Astrophysics Data System (ADS)

Based on a thorough review of background information on the performance of materials in condensing gas fired furnace heat exchangers and in similar corrosive environments candidate materials were selected and tested on one of two identical test rigs built to provide the varying corrosive conditions encountered in an actual gas fired condensing system heat exchanger. The 32 different materials tested in a one month screening test included: mild, low alloy, galvanized, solder coated and CaCO3 dipped galvanized steel, porcelain, epoxy, teflon and nylon coated and alonized mild steel; austenitic, ferritic, low interstitial Ti stabilized ferritic, and high alloy stainless steels; aluminum alloy anodized and porcelain coated aluminum; copper and cupronickel alloys, solder coated copper; and titanium.

Lahtvee, T.; Khoo, S. W.; Schaus, O. O.

1981-02-01

214

Experimental investigation on fiber and CO2 inert gas fusion cutting of AZ31 magnesium alloy sheets  

NASA Astrophysics Data System (ADS)

The influence of processing parameters and laser source type on cutting edge quality of AZ31 magnesium alloy sheets and differences in cutting efficiency between fiber and CO2 lasers were studied. A first part of the cutting experiments compared a fiber and CO2 laser source when cutting 1 mm thick sheets in continuous wave mode and using Argon as an assist gas. The effects of cutting speed and assist gas pressure were investigated and optimal conditions were identified. In the second part of the experimental investigation, 3.3 mm thick sheets were cut using fiber laser. Focal position and cutting speed were varied in order to detect the optimal combination of processing parameters to obtain the best edge quality. For both sheet thicknesses investigated, surface roughness, dross height, and striation pattern inclination were measured. Cutting quality assessment and classification was carried out according to UNI EN ISO 9013 standard. Results showed that productivity, process efficiency and cutting edges quality obtained using fiber lasers outperform CO2 laser performances and therefore are considered suitable for application like sheet metal trimming.

Scintilla, L. D.; Tricarico, L.

2013-03-01

215

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

Microsoft Academic Search

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

Vitaly V. Kocharovsky; Vladimir V. Kocharovsky

2010-01-01

216

Method of improving steam flood conformance with steam flooding agents without a non-condensable gas  

Microsoft Academic Search

The disclosed invention is a group of novel steam foaming agents for injection with steam to decrease permeability in steam sept zones. They are effective without the coinjection on a non-condensable gas. The foaming agents have the general formula: RO(R'O) \\/SUB n\\/ R''SOāM where R is an alkyl radical, branched or linear, having from about 15 to about 21 carbon

J. T. Hawkins; Z. Z. Gassmann

1985-01-01

217

Theory of light and atom scattering in the Bose-Einstein condensate of a dilute gas  

SciTech Connect

A semiclassical theory of superradiant light scattering from a Bose-Einstein condensate of a dilute gas is developed without recourse to the mean field approximation. The dynamics and spectrum of superradiant field, as well as the kinetics of formation of coherent atomic states with various translational momenta are calculated. The results are qualitatively consistent with experimental data for atoms scattered in the backward direction relative to that of the exciting laser beam propagation.

Avetisyan, Ya. A. [Russian Academy of Sciences, Institute of Problems of Fine Mechanics and Control (Russian Federation); Trifonov, E. D. [Herzen State Pedagogical University (Russian Federation)], E-mail: thphys@herzen.spb.ru

2006-11-15

218

Crossover from a Molecular Bose-Einstein Condensate to a Degenerate Fermi Gas  

Microsoft Academic Search

We demonstrate a reversible conversion of a 6Li2 molecular Bose-Einstein condensate to a degenerate Fermi gas of atoms by adiabatically crossing a Feshbach resonance. By optical in situ imaging, we observe a smooth change of the cloud size in the crossover regime. On the Feshbach resonance, the ensemble is strongly interacting and the measured cloud size is 75(7)% of the

M. Bartenstein; A. Altmeyer; S. Riedl; S. Jochim; C. Chin; J. Hecker Denschlag; R. Grimm

2004-01-01

219

Aspects of hyperspherical adiabaticity in an atomic-gas Bose-Einstein condensate  

Microsoft Academic Search

Excitation of an atomic-gas Bose-Einstein condensate (BEC) in the zeroth-order ground-state channel is studied with the hyperspherical adiabatic method of Bohn [Bohn , Phys. Rev. A 58, 584 (1998)] suitably generalized to accommodate the anisotropic trapping potential. The method exploits the system's size as an adiabatic parameter so that the explicit size dependence is immediately conducive to the virial theorem.

Daisuke Kushibe; Masaki Mutou; Toru Morishita; Shinichi Watanabe; Michio Matsuzawa

2004-01-01

220

Local observation of pair condensation in a Fermi gas at unitarity.  

PubMed

We present measurements of the local (homogeneous) density-density response function of a Fermi gas at unitarity using spatially resolved Bragg spectroscopy. By analyzing the Bragg response across one axis of the cloud, we extract the response function for a uniform gas which shows a clear signature of the Bose-Einstein condensation of pairs of fermions when the local temperature drops below the superfluid transition temperature. The method we use for local measurement generalizes a scheme for obtaining the local pressure in a harmonically trapped cloud from the line density and can be adapted to provide any homogeneous parameter satisfying the local density approximation. PMID:24679273

Lingham, M G; Fenech, K; Hoinka, S; Vale, C J

2014-03-14

221

Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and -196 °C  

NASA Astrophysics Data System (ADS)

2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (-196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at -196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled ? (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

Lei, Xuefeng; Deng, Ying; Yin, Zhimin; Xu, Guofu

2014-04-01

222

The Role of Spraying Parameters and Inert Gas Shrouding in Hybrid Water-Argon Plasma Spraying of Tungsten and Copper for Nuclear Fusion Applications  

NASA Astrophysics Data System (ADS)

Tungsten-based coatings have potential application in the plasma-facing components in future nuclear fusion reactors. By the combination of refractory tungsten with highly thermal conducting copper, or steel as a construction material, functionally graded coatings can be easily obtained by plasma spraying, and may result in the development of a material with favorable properties. During plasma spraying of these materials in the open atmosphere, oxidation is an important issue, which could have adverse effects on their properties. Among the means to control it is the application of inert gas shrouding, which forms the subject of this study and represents a lower-cost alternative to vacuum or low-pressure plasma spraying, potentially applicable also for spraying of large surfaces or spacious components. It is a continuation of recent studies focused on the effects of various parameters of the hybrid water-argon torch on the in-flight behavior of copper and tungsten powders and the resultant coatings. In the current study, argon shrouding with various configurations of the shroud was applied. The effects of torch parameters, such as power and argon flow rate, and powder morphology were also investigated. Their influence on the particle in-flight behavior as well as the structure, composition and properties of the coatings were quantified. With the help of auxiliary calculations, the mass changes of the powder particles, associated with oxidation and evaporation, were assessed.

Mat?jķ?ek, J.; Kavka, T.; Bertolissi, G.; Ctibor, P.; Vilémovį, M.; Mušįlek, R.; Nevrlį, B.

2013-06-01

223

Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and -196 °C  

NASA Astrophysics Data System (ADS)

2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (-196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at -196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled ? (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

Lei, Xuefeng; Deng, Ying; Yin, Zhimin; Xu, Guofu

2014-06-01

224

Controlled inert gas environment for enhanced chlorine and fluorine detection in the visible and near-infrared by laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Efficient quantitative detection for halogens is necessary in a wide range of applications, ranging from pharmaceutical products to air polluting hazardous gases or organic compounds used as chemical weapons. Detection of the non-metallic elements such as fluorine (F) and chlorine (Cl) presents particular difficulty, because strong emission lines originating from their resonance states lie in the VUV spectral range (110-190 nm). In the present work we detect F and Cl in the upper visible and in the near IR (650-850 nm) under controlled inert gas ambient atmosphere. Investigation of the controlled atmosphere effects suggests that there exists an optimum pressure range that optimizes signal strength and quality. Ablation and ionization were achieved with a UV laser at 355 nm, and a gated GaAs photocathode-based detector was used for detection with quantum efficiency in the range of 20% in the wavelengths of interest. Our results indicate that our approach provides quantitative detection with linearity over at least two orders of magnitude that is achieved without the need for Internal Standardization Method, and improved limits of detection. In particular, fluorine has been detected for concentration values down to 0.03 wt.% Definite spectral assignment revealing all major emission lines centered around 837 nm for F and 687 nm for Cl has been obtained for the first time in Laser-induced breakdown spectroscopy application.

Asimellis, George; Hamilton, Stephen; Giannoudakos, Aggelos; Kompitsas, Michael

2005-08-01

225

Effects of CaF2 Coating on the Microstructures and Mechanical Properties of Tungsten Inert Gas Welded AZ31 Magnesium Alloy Joints  

NASA Astrophysics Data System (ADS)

The effects of CaF2 coating on the macromorphologies of the welded seams were studied by morphological analysis. Microstructures and mechanical properties of butt joints welded with different amounts of CaF2 coatings were investigated using optical microscopy and tensile tests. The welding defects formed in the welded seams and the fracture surfaces were analyzed by scanning electron microscopy. An increase in the amount of CaF2 coating deteriorated the appearances of the welded seams but it improved the weld penetration depth and the depth/width ( D/ W) ratio of the tungsten inert gas (TIG) welded joints. The ?-Mg grains and Mg17(Al,Zn)12 intermetallic compound (IMC) were coarser in the case of a higher amount of CaF2 coating. The increase in the amount of CaF2 coating reduced the porosities and total length of solidification cracks in the fusion zone (FZ). The ultimate tensile strength (UTS) value and elongation increased at first and then decreased sharply.

Shen, Jun; Wang, Linzhi; Peng, Dong; Wang, Dan

2012-11-01

226

Inert Carbon Free Radicals.  

National Technical Information Service (NTIS)

The first inert carbon free radicals, completely dissociated and with both chemical and thermal stability, are described. These compounds belong to the perchlorocarbon class and are exemplified by perchlorotriphenylmethyl, perchlorodiphenylmethyl, and rel...

M. Ballester

1968-01-01

227

Studies on pressure response of gas bubbles contributions of condensed droplets in bubbles generated by a uniform nucleation  

Microsoft Academic Search

The response of a tiny gas bubble under reduced pressure is investigated in its relation to cavitation. Equations of motion are formulated for gas mixtures inside the bubble and numerical calculations performed for several examples. The conclusions are as follows: (1) at the onset of bubble growth, the gas mixture inside it adiabatically expands and the temperature decreases. Condensed droplets

Y. Matsumoto

1988-01-01

228

Method and apparatus for removing non-condensible gas from a working fluid in a binary power system  

DOEpatents

Apparatus for removing non-condensible gas from a working fluid utilized in a thermodynamic system comprises a membrane having an upstream side operatively connected to the thermodynamic system so that the upstream side of the membrane receives a portion of the working fluid. The first membrane separates the non-condensible gas from the working fluid. A pump operatively associated with the membrane causes the portion of the working fluid to contact the membrane and to be returned to the thermodynamic system.

Mohr, Charles M. (Idaho Falls, ID); Mines, Gregory L. (Idaho Falls, ID); Bloomfield, K. Kit (Idaho Falls, ID)

2002-01-01

229

Microbial reduction of sulfate injected to gas condensate plumes in cold groundwater.  

PubMed

Despite a rapid expansion over the past decade in the reliance on intrinsic bioremediation to remediate petroleum hydrocarbon plumes in groundwater, significant research gaps remain. Although it has been demonstrated that bacterial sulfate reduction can be a key electron accepting process in many petroleum plumes, little is known about the rate of this reduction process in plumes derived from crude oil and gas condensates at cold-climate sites (mean temperature <10 degrees C), and in complex hydrogeological settings such as silt/clay aquitards. In this field study, sulfate was injected into groundwater contaminated by gas condensate plumes at two petroleum sites in Alberta, Canada to enhance in-situ bioremediation. In both cases the groundwater near the water table had low temperature (6-9 degrees C). Monitoring data had provided strong evidence that bacterial sulfate reduction was a key terminal electron accepting process (TEAP) in the natural attenuation of dissolved hydrocarbons at these sites. At each site, water with approximately 2000 mg/L sulfate and a bromide tracer was injected into a low-sulfate zone within a condensate-contaminant plume. Monitoring data collected over several months yielded conservative estimates for sulfate reduction rates based on zero-order kinetics (4-6 mg/L per day) or first-order kinetics (0.003 and 0.01 day(-1)). These results favor the applicability of in-situ bioremediation techniques in this region, under natural conditions or with enhancement via sulfate injection. PMID:17292997

Van Stempvoort, Dale R; Armstrong, James; Mayer, Bernhard

2007-07-17

230

Transport Membrane Condenser for Water and Energy Recovery from Power Plant Flue Gas  

SciTech Connect

The new waste heat and water recovery technology based on a nanoporous ceramic membrane vapor separation mechanism has been developed for power plant flue gas application. The recovered water vapor and its latent heat from the flue gas can increase the power plant boiler efficiency and reduce water consumption. This report describes the development of the Transport Membrane Condenser (TMC) technology in details for power plant flue gas application. The two-stage TMC design can achieve maximum heat and water recovery based on practical power plant flue gas and cooling water stream conditions. And the report includes: Two-stage TMC water and heat recovery system design based on potential host power plant coal fired flue gas conditions; Membrane performance optimization process based on the flue gas conditions, heat sink conditions, and water and heat transport rate requirement; Pilot-Scale Unit design, fabrication and performance validation test results. Laboratory test results showed the TMC system can exact significant amount of vapor and heat from the flue gases. The recovered water has been tested and proved of good quality, and the impact of SO{sub 2} in the flue gas on the membrane has been evaluated. The TMC pilot-scale system has been field tested with a slip stream of flue gas in a power plant to prove its long term real world operation performance. A TMC scale-up design approach has been investigated and an economic analysis of applying the technology has been performed.

Dexin Wang

2012-03-31

231

Synthesis of tungsten disulphide nanoparticles by the chemical vapor condensation method  

Microsoft Academic Search

Crystalline tungsten disulphide nanoparticles were successfully synthesized by the chemical vapor condensation (CVC) method. The process performed as decomposition of tungsten hexacarbonyl over sulphur vapor in inert gas flow, where WS2 nanoparticles were synthesized by direct reaction between as formed pure tungsten nanoclusters and sulphur vapor. Influence of experimental parameters on shape, size distribution, structure and phase composition of nanoparticles

E. S. Vasilyeva; O. V. Tolochko; B. K. Kim; D. W. Lee; D. S. Kim

2009-01-01

232

Hot nanoindentation in inert environments  

NASA Astrophysics Data System (ADS)

An instrument capable of performing nanoindentation at temperatures up to 500 °C in inert atmospheres, including partial vacuum and gas near atmospheric pressures, is described. Technical issues associated with the technique (such as drift and noise) and the instrument (such as tip erosion and radiative heating of the transducer) are identified and addressed. Based on these considerations, preferred operation conditions are identified for testing on various materials. As a proof-of-concept demonstration, the hardness and elastic modulus of three materials are measured: fused silica (nonoxidizing), aluminum, and copper (both oxidizing). In all cases, the properties match reasonably well with published data acquired by more conventional test methods.

Trenkle, Jonathan C.; Packard, Corinne E.; Schuh, Christopher A.

2010-07-01

233

Inert gas ion source program  

NASA Technical Reports Server (NTRS)

THe original 12 cm hexagonal magneto-electrostatic containment discharge chamber has been optimized for argon and xenon operation. Argon mass utilization efficiencies of 65 to 77 percent were achieved at keeper-plus-main discharge energy consumptions of 200 to 458 eV/ion, respectively. Xenon performance of 84 to 96 percent mass utilization was realized at 203 to 350 eV/ion. The optimization process and test results are discussed.

Ramsey, W. D.

1978-01-01

234

Inert gas ion thruster development  

NASA Technical Reports Server (NTRS)

Two 12 cm magneto-electrostatic containment (MESC) ion thrusters were performance mapped with argon and xenon. The first, hexagonal, thruster produced optimized performance of 48.5to 79 percent argon mass utilization efficiencies at discharge energies of 240 to 425 eV/ion, respectively, Xenon mass utilization efficiencies of 78 to 95 percent were observed at discharge energies of 220 to 290 eV/ion with the same optimized hexagonal thruster. Changes to the cathode baffle reduced the discharge anode potential during xenon operation from approximately 40 volts to about 30 volts. Preliminary tests conducted with the second, hemispherical, MESC thruster showed a nonuniform anode magnetic field adversely affected thruster performance. This performance degradation was partially overcome by changes in the boundary anode placement. Conclusions drawn the hemispherical thruster tests gave insights into the plasma processes in the MESC discharge that will aid in the design of future thrusters.

Ramsey, W. D.

1980-01-01

235

Cal Canal Field, California: case history of a tight and abnormally pressured gas condensate reservoir  

SciTech Connect

The Cal Canal Field, situated in the San Joaquin Valley near Bakersfield, California, produces a rich (280 bbl/MMSCF) gas condensate from an average depth of 11,500 feet. The upper Miocene Stevens Sand, the producing formation in the field, is a very tight, abnormally pressured gas condensate reservoir. The average reservoir parameters are 12 percent porosity, .01 to .1 md permeability and a connate water saturation of 59%. The dew point pressure of 5835 psi is 1508 psi below the initial reservoir pressure. The material balance method, corrected for abnormal pressure, indicates an original wet gas-in-place of 103.3 BSCF. Production performance history suggests that the ultimate recovery from the field will be approximately + or - 10% of the original wet GIP. Such a poor recovery could be attributed to retrograde fallout and increasing water saturation in the vicinity of the wellbores. This paper presents an analysis of the reservoir characteristics and a review of its performance to date. The purpose of the study was to investigate the feasibility of improving hydrocarbon recovery from the field.

Engineer, R.

1985-03-01

236

Advances in SAW gas sensors based on the condensate-adsorption effect.  

PubMed

A surface-acoustic-wave (SAW) gas sensor with a low detection limit and fast response for volatile organic compounds (VOCs) based on the condensate-adsorption effect detection is developed. In this sensor a gas chromatography (GC) column acts as the separator element and a dual-resonator oscillator acts as the detector element. Regarding the surface effective permittivity method, the response mechanism analysis, which relates the condensate-adsorption effect, is performed, leading to the sensor performance prediction prior to fabrication. New designs of SAW resonators, which act as feedback of the oscillator, are devised in order to decrease the insertion loss and to achieve single-mode control, resulting in superior frequency stability of the oscillator. Based on the new phase modulation approach, excellent short-term frequency stability (±3 Hz/s) is achieved with the SAW oscillator by using the 500 MHz dual-port resonator as feedback element. In a sensor experiment investigating formaldehyde detection, the implemented SAW gas sensor exhibits an excellent threshold detection limit as low as 0.38 pg. PMID:22247697

Liu, Jiuling; Wang, Wen; Li, Shunzhou; Liu, Minghua; He, Shitang

2011-01-01

237

Method of improving steam flood conformance with steam flooding agents without a non-condensable gas  

SciTech Connect

The disclosed invention is a group of novel steam foaming agents for injection with steam to decrease permeability in steam sept zones. They are effective without the coinjection on a non-condensable gas. The foaming agents have the general formula: RO(R'O) /SUB n/ R''SO/sub 3/M where R is an alkyl radical, branched or linear, having from about 15 to about 21 carbon atoms in the alkyl chain, R' is ethyl or propyl, n has an average value of about 2 to about 5, R'' is ethyl, propyl, hydroxypropyl or butyl and M is an alkali metal or ammonium ion.

Hawkins, J. T.; Gassmann, Z. Z.

1985-09-10

238

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

2010-04-28

239

Gas scavenging of insoluble vapors: Condensation of methyl salicylate vapor onto evaporating drops of water  

NASA Astrophysics Data System (ADS)

We have observed the evaporation of acoustically levitated water drops at 0 and 32% relative humidity in a moving gas stream which is nearly saturated with methyl salicylate vapor. The initial evaporation rate is characteristic of a pure water drop and gradually slows until the evaporation rate becomes that of pure methyl salicylate. The quantity of condensed methyl salicylate exceeds its Henry's law solubility in water by factors of more than 30-50. This apparent violation of Henry's law agrees with the concentration enhancements in the liquid phase found by glotfelty et al. (1987, Nature235, 602-605) during their field measurements of organophorus pesticides in fog water. Under our conditions, visual evidence demonstrates the presence of two liquid phases, thus invalidating the use of Henry's law. A continuum evaporation-condensation model for an immiscible two-component system which accounts for evaporative self-cooling of the drop correctly predicts the amount of methyl salicylate condensed onto the water drops.

Seaver, Mark; Peele, J. R.; Rubel, Glenn O.

240

Observation of the Scissors Mode and Evidence for Superfluidity of a Trapped Bose-Einstein Condensed Gas  

Microsoft Academic Search

We report the observation of the scissors mode of a Bose-Einstein condensed gas of 87Rb atoms in a magnetic trap, which gives direct evidence of superfluidity in this system. The scissors mode of oscillation is excited by a sudden rotation of the anisotropic trapping potential. For a gas above Tc (normal fluid) we detect the occurrence of oscillations at two

O. M. Maragņ; S. A. Hopkins; J. Arlt; E. Hodby; G. Hechenblaikner; C. J. Foot

2000-01-01

241

Horizontal in-tube condensation in the presence of a noncondensable gas  

NASA Astrophysics Data System (ADS)

A horizontal heat exchanger design has been proposed for the Passive Containment Cooling System (PCCS) condenser of future Boiling Water Reactors (BWR). Compared to the vertical design, it has several advantages, but the challenge is that there is a lack of mechanistic understanding of the heat transfer and fluid flow phenomena occurring in the heat exchanger tubes. There is also the need for mechanistic analysis tools that can assess condenser performance. This research experimentally investigates the local heat transfer from the condensation of steam in the presence of noncondensable gas in a single horizontal tube. To capture the asymmetrical nature of horizontal two-phase flow and heat transfer, the heat fluxes at the top and bottom of the condenser tube were obtained. A novel thermocouple was designed and fabricated to accurately measure the inside wall temperature from which a local heat flux can be deduced. The calibration technique of the thermocouple pairs was also developed. This local heat flux measurement technique is an original method for data which had previously been unattainable. It is applicable to phase-change heat exchangers of any inclination. Tests with parameters that cover both design base accident and severe accident conditions have been performed. Analysis showed that the heat transfer at the top of the tube is much better than that at the bottom of the tube, which shows that for most of the conditions the liquid phase distribution has a great effect on the heat transfer. The effect of noncondensable gas has been qualitatively studied both locally and globally from the experimental data. A mechanistic model was developed independent of the experimental data and was verified by the experimental data. Diffusion layer theory was used to account for the effect of noncondensable gas. For annular flow, the phenomenon inside the tube was assumed to be symmetrical. For wavy and stratified flow, the tube is divided into top and bottom parts peripherally based on the local phase distribution. The heat transfer mode across the liquid film was considered differently for the top and bottom part of the tube. The predictions from the mechanistic model were compared with the experimental data both locally and globally, and the agreement was satisfactory.

Wu, Tiejun

242

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.; Pelįez, J. R.; de Elvira, J. Ruiz

2013-01-01

243

Bose-Einstein condensation temperature of dipolar gas in anisotropic harmonic trap  

SciTech Connect

We consider a dilute gas of dipole moments in an arbitrary harmonic trap and treat both the short-range, isotropic {delta} interaction and the long-range, anisotropic dipole-dipole interaction perturbatively. In this way, we calculate the leading shift of the critical temperature with respect to that of an ideal gas as a function of the relative orientation of the dipole moments with respect to the harmonic trap axes. In particular, we determine those magic angles, where the dipolar shift of the Bose-Einstein condensation temperature vanishes. Furthermore, we show for the parameters of the ongoing {sup 52}Cr BEC experiment of Pfau and co-workers that this dipolar shift can be enhanced by increasing the number of particles, the geometrical mean trap frequency, and the anisotropy of the trap.

Glaum, K.; Pelster, A. [Fachbereich Physik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Fachbereich Physik, Campus Duisburg, Universitaet Duisburg-Essen, Lotharstrasse 1, 47048 Duisburg (Germany)

2007-08-15

244

Use of compositional simulation in the management of Arun gas condensate reservoir  

SciTech Connect

This paper describes the simulation of the Arun gas condensate reservoir using a fully compositional simulator, COSMOS (COmpositional System Mobil Oil Simulator). The reservoir is a Miocene carbonate reef complex which occurs at a depth of approximately 10,000 feet, and is up to 1,000 feet thick in some areas. The Arun reservoir is a compositionally dynamic system. The purpose of this simulation study was to predict future reservoir performance under various demand scenarios and optimize gas and NGL recovery. The simulation model utilizes the Peng-Robinson equation of state to account for the compositionally dynamic behavior of the reservoir in predictions of future performance. The equation of state was modified to incorporate special features for Arun such as water vaporization in the reservoir under high temperature conditions.

Sutan-Assin, T.; Rastogi, S.C.; Abdullah, M. (Mobil Oil Indonesia (ID)); Hidayat, D. (BKKA - Pertamina (ID)); Bette, S.; Heineman, R.F. (Mobil R and D Corp. (US))

1988-01-01

245

?-DIMENSIONAL Ideal Quantum q-GAS:. Bose-Einstein Condensation and ?-POINT Transition  

NASA Astrophysics Data System (ADS)

We consider an ideal quantum q-gas in ? spatial dimensions and energy spectrum ?i? p? Departing from the Hamiltonian H=?[N], we study the effect of the deformation on thermodynamic functions and equation of state of that system. The virial expansion is obtained for the high temperature (or low density) regime. The critical temperature is higher than in non-deformed ideal gases. We show that Bose-Einstein condensation always exists (unless when ?/?=1) for finite q but not for q=?. Employing numerical calculations and selecting for v/? the values 3/2, 2 and 3, we show the critical temperature as a function of q, the specific heat CV and the chemical potential µ as functions of {T {T {Tcq }}} ; } {Tcq }} for q=1.05 and q=4.5. CV exhibits a ?-point discontinuity in all cases, instead of the cusp singularity found in the usual ideal gas. Our results indicate that physical systems which have quantum symmetries can exhibit Bose-Einstein condensation phenomenon, the critical temperature being favored by the deformation parameter.

R-Monteiro, M.; Roditi, Itzhak; Rodrigues, Ligia M. C. S.

246

The improvement of the effectiveness of using natural gas in hot-water boilers by means of condensing economizers  

NASA Astrophysics Data System (ADS)

The paper describes the results of the study of the mathematical model of a condensing economizer (CE) interacting with the technological parameter of the particular district heating station. This model has been developed by the authors. It is shown that the CE, due to condensation of water vapor and augmentation of convective heat exchange between products of natural gas combustion, makes it possible to save up to 8% of fuel.

Vnukov, A. K.; Rozanova, F. A.

2013-07-01

247

Methanol Droplet Combustion in Oxygen-Inert Environments in Microgravity  

NASA Technical Reports Server (NTRS)

The Flame Extinguishment (FLEX) experiment that is currently underway in the Combustion Integrated Rack facility onboard the International Space Station is aimed at understanding the effects of inert diluents on the flammability of condensed phase fuels. To this end, droplets of various fuels, including alkanes and alcohols, are burned in a quiescent microgravity environment with varying amounts of oxygen and inert diluents to determine the limiting oxygen index (LOI) for these fuels. In this study we report experimental observations of methanol droplets burning in oxygen-nitrogen-carbon dioxide and oxygen-nitrogen-helium gas mixtures at 0.7 and 1 atmospheric pressures. The initial droplet size varied between approximately 1.5 mm and 4 mm to capture both diffusive extinction brought about by insufficient residence time at the flame and radiative extinction caused by excessive heat loss from the flame zone. The ambient oxygen concentration varied from a high value of 30% by volume to as low as 12%, approaching the limiting oxygen index for the fuel. The inert dilution by carbon dioxide and helium varied over a range of 0% to 70% by volume. In these experiments, both freely floated and tethered droplets were ignited using symmetrically opposed hot-wire igniters and the burning histories were recorded onboard using digital cameras, downlinked later to the ground for analysis. The digital images yielded droplet and flame diameters as functions of time and subsequently droplet burning rate, flame standoff ratio, and initial and extinction droplet diameters. Simplified theoretical models correlate the measured burning rate constant and the flame standoff ratio reasonably well. An activation energy asymptotic theory accounting for time-dependent water dissolution or evaporation from the droplet is shown to predict the measured diffusive extinction conditions well. The experiments also show that the limiting oxygen index for methanol in these diluent gases is around 12% to 13% oxygen by volume.

Nayagam, Vedha; Dietrich, Daniel L.; Hicks, Michael C.; Williams, Forman A.

2013-01-01

248

Investigation into the determination of trimethylarsine in natural gas and its partitioning into gas and condensate phases using (cryotrapping)\\/gas chromatography coupled to inductively coupled plasma mass spectrometry and liquid\\/solid sorption techniques  

Microsoft Academic Search

Speciation of trialkylated arsenic compunds in natural gas, pressurized and stable condensate samples from the same gas well was performed using (Cryotrapping) Gas Chromatography-Inductively Coupled Plasma Mass Spectrometry. The major species in all phases investigated was found to be trimethylarsine with a highest concentration of 17.8 ng\\/L (As) in the gas phase and 33.2 ?g\\/L (As) in the stable condensate phase. The

E. M. Krupp; C. Johnson; C. Rechsteiner; M. Moir; D. Leong; J. Feldmann

2007-01-01

249

Anomalously bright UV lines of Fe II as a probe of gas condensations in the vicinity of hot stars  

NASA Astrophysics Data System (ADS)

Two UV lines of Fe II at 2507/2509 Å are extremely bright in spatially resolved HST/STIS spectra of dense gas condensations (the so called Weigelt blobs) close to the central star of ? Carinae. The lines also appear unresolved in HST/FOS spectra of the star AE And. Under normal conditions the lines should hardly be observable. Based on recent studies of the formation of the ?ambda?ambda2507/2509 lines as part of a radiative cycle driven by HLy? pumping and including stimulated emission we propose the possibility of using them as a probe of non-homogeneities in gas condensations located outside hot, massive stars.

Johansson, S.; Letokhov, V. S.

2003-12-01

250

Method of producing hydrogen, and rendering a contaminated biomass inert  

DOEpatents

A method for rendering a contaminated biomass inert includes providing a first composition, providing a second composition, reacting the first and second compositions together to form an alkaline hydroxide, providing a contaminated biomass feedstock and reacting the alkaline hydroxide with the contaminated biomass feedstock to render the contaminated biomass feedstock inert and further producing hydrogen gas, and a byproduct that includes the first composition.

Bingham, Dennis N. (Idaho Falls, ID) [Idaho Falls, ID; Klingler, Kerry M. (Idaho Falls, ID) [Idaho Falls, ID; Wilding, Bruce M. (Idaho Falls, ID) [Idaho Falls, ID

2010-02-23

251

Chemical reactions in the gas phase and in condensed matter: From wavefunctions to density operators  

NASA Astrophysics Data System (ADS)

This contribution generalizes the treatment of chemical reactions in the gas phase based on the reaction channel decomposition of the wavefunction, by introducing a similar channel decomposition of the statistical density operator valid also for condensed phases such as liquid solutions and solid surfaces. Coupled equations for the channel components of the density operator are derived and a brief presentation is given of their partial Wigner transform, which leads to a general treatment for coupling quantum and classical variables. This provides a general approach for reactions involving electronically excited states in many-atom systems. It is pointed out that reactions involving coupled quantal and classical variables can be correctly described provided (a) initial conditions for trajectories are generated from quantal distributions and (b) the bundle of trajectories for the whole initial classical phase space is propagated coupled to the quantal elements of the density matrix and used in the calculation of reaction flux averages.

Micha, David A.

252

Fast transit gas- and condensed-phase chemistry of energetic materials  

SciTech Connect

An experimental system is being developed to study the fast transient kinetics governing solid-phase decomposition and subsequent interaction with decomposition products. The first phase of this work addresses the decomposition step. The experimental system integrates a thin-film sample configuration with two chemical diagnostic techniques, time-of-flight mass spectrometry and time-resolved infrared spectral photography, and a pulsed-laser heat source. This system is designed to examine both condensed-phase mechanisms and concurrent gas-phase species evolution from samples at temperatures up to 1000{degree}C with microsecond temporal resolution. Tests are underway to demonstrate and assess the use of thin-film samples with the experimental system. Results of these tests, the diagnostic capabilities of the experimental system, and the advantages, preparation and characterization of thin-film samples are presented. 19 refs., 4 figs.

Skocypec, R.D.; Erickson, K.L.; Renlund, A.M.; Trott, W.M.

1989-01-01

253

Stability of Chapman Jouguet detonations for a stiffened-gas model of condensed-phase explosives  

NASA Astrophysics Data System (ADS)

The analysis of the linear stability of a planar Chapman Jouguet detonation wave is reformulated for an arbitrary caloric (incomplete) equation of state in an attempt to better represent the stability properties of detonations in condensed-phase explosives. Calculations are performed on a ‘stiffened-gas’ equation of state which allows us to prescribe a finite detonation Mach number while simultaneously allowing for a detonation shock pressure that is substantially larger than the ambient pressure. We show that the effect of increasing the ambient sound speed in the material, for a given detonation speed, has a stabilizing effect on the detonation. We also show that the presence of the slow reaction stage, a feature of detonations in certain types of energetic materials, where the detonation structure is characterized by a fast reaction stage behind the detonation shock followed by a slow reaction stage, tends to have a destabilizing effect.

Short, Mark; Bdzil, John B.; Anguelova, Iana I.

2006-04-01

254

Ground-State Energy and Condensate Density of a Dilute Bose Gas Revisited  

NASA Astrophysics Data System (ADS)

The ground-state energy per particle E/N and condensate density n0 of a dilute Bose gas are studied with a self-consistent perturbation expansion satisfying the Hugenholtz--Pines theorem and conservation laws simultaneously. A class of Feynman diagrams for the self-energy, which has escaped consideration so far, is shown to add an extra constant cip˜ O(1) to the expressions reported by Lee et al. [Phys. Rev. 106 (1957) 1135] as E/N=(2?\\hbar2an/m)[1+(128/15\\sqrt?+16cip/5)\\sqrt{a3n}] and n0/n=1-(8/3\\sqrt?+cip)\\sqrt{a3n}, where a, n, and m are are the s-wave scattering length, particle density, and particle mass, respectively. We present a couple of estimates for cip; the third-order perturbation expansion yields cip=0.412.

Tsutsui, Kazumasa; Kita, Takafumi

2013-06-01

255

Inert gases in Sea of Fertility regolith  

NASA Technical Reports Server (NTRS)

The content and isotopic composition were studied of inert gases -- He, Ne, Ar, Kr, and Xe -- in samples of lunar regolith returned by the Luna 16 automatic station. The samples were taken from depths of about 12 and 30 cm. The high concentrations of inert gases exceed by several orders their concentrations observed in ordinary stony meteorites. The gases in lunar regolith were a complex mixture of gases of different origins: Solar, cosmogenic, radiogenic, and so on. Solar wind gases predominated, distributed in the thin surficial layer of the regolith grains. The concentrations of these gases in the surficial layer is several cubic centimeters per gram. The isotopic composition of the inert gases of solar origin approaches their composition measured in gas-rich meteorites.

Vinogradov, A. P.; Zadorozhnyy, I. K.

1974-01-01

256

Pyrolysis process for producing condensed stabilized hydrocarbons utilizing a beneficially reactive gas  

DOEpatents

In a process for recovery of values contained in solid carbonaceous material, the solid carbonaceous material is comminuted and then subjected to pyrolysis, in the presence of a carbon containing solid particulate source of heat and a beneficially reactive transport gas in a transport flash pyrolysis reactor, to form a pyrolysis product stream. The pyrolysis product stream contains a gaseous mixture and particulate solids. The solids are separated from the gaseous mixture to form a substantially solids-free gaseous stream which comprises volatilized hydrocarbon free radicals newly formed by pyrolysis. Preferably the solid particulate source of heat is formed by oxidizing part of the separated particulate solids. The beneficially reactive transport gas inhibits the reactivity of the char product and the carbon-containing solid particulate source of heat. Condensed stabilized hydrocarbons are obtained by quenching the gaseous mixture stream with a quench fluid which contains a capping agent for stabilizing and terminating newly formed volatilized hydrocarbon free radicals. The capping agent is partially depleted of hydrogen by the stabilization and termination reaction. Hydrocarbons of four or more carbon atoms in the gaseous mixture stream are condensed. A liquid stream containing the stabilized liquid product is then treated or separated into various fractions. A liquid containing the hydrogen depleted capping agent is hydrogenated to form a regenerated capping agent. At least a portion of the regenerated capping agent is recycled to the quench zone as the quench fluid. In another embodiment capping agent is produced by the process, separated from the liquid product mixture, and recycled.

Durai-Swamy, Kandaswamy (Culver City, CA)

1982-01-01

257

Roeggaskondensering med varmepumpe paa flisfyrede kedelanlaeg. (Condensing of steam in flue gas using a heat pump system in relation to a wood chip fired boiler).  

National Technical Information Service (NTIS)

The aim of this report is to describe existing methods for condensing steam water in flue gas in relation to combustion of forest biomass, and to describe the implementation of a plant for condensing of water in flue gas on an existing installation for co...

A. Evald B. Petersen C. Bisgaard G. Vogel

1989-01-01

258

The partitioning of Nitric Acid between the gas phase and condensed phase of aqueous sulfate aerosols.  

NASA Astrophysics Data System (ADS)

The heterogeneous hydrolysis of N2O_5 on aqueous aerosol surfaces is an important source of atmospheric HNO3. We generated HNO3 by heterogeneous hydrolysis of N2O_5 on aqueous ammonium and sodium sulfate aerosols and studied its partitioning between the gas phase and the aerosol phase. The experiments were performed in the large aerosol chamber at the FZ-Jülich at several relative humidities. Gas phase processes and the composition of the aerosols were monitored on-line simultaneously by FTIR spectroscopy and by Steam Jet Aerosol Collection/Ion Chromatography. The aerosol size distributions in the range of 20 nm to 5 ? m were measured by differential electromobility classification and by aerodynamic particle sizing. In the presence of aqueous bisulfate and sulfate aerosols a fast heterogeneous formation HNO3 is observed. (The reaction probability of N2O_5 is about 0.02.) In the case of the acidic bisulfate aerosols the major fraction of heterogeneously formed HNO3 resides in the gas phase. For neutral sulfate aerosols a significant fraction of HNO3 is taken up by the condensed phase of the aerosols. This leads to a distinctive growth of the aerosol population during the heterogeneous hydrolysis of N2O_5, which is observable in the number size distribution as well as in IR extinction measurements. The observed partitioning of HNO3 between gas phase and aqueous aerosol phase can be quantitatively understood by a Pitzer based thermodynamic model for salt solutions of high ionic strength. The model calculations and low resolution FTIR spectroscopy demonstrate that protonation of sulfate to bisulfate is the driving force for the uptake of HNO3 in neutral sulfate aerosols.

Mentel, T. F.; Folkers, M.; Sebald, H.; Wahner, A.

2001-12-01

259

The potential for intrinsic bioremediation of BTEX hydrocarbons in soil\\/ground water contaminated with gas condensate  

Microsoft Academic Search

Gas condensate liquids contaminate soil and ground water at two gas production sites in the Denver Basin, CO. A detailed field\\u000a study was carried out at these sites to determine the applicability of intrinsic bioremediation as a remediation option. Ground\\u000a water monitoring at the field sites and analysis of soil cores suggested that intrinsic bioremediation is occurring at the\\u000a sites

Abhijeet P. Borole; Kerry L. Sublette; Kevin T. Raterman; Minoo Javanmardian; J. Berton Fisher

1997-01-01

260

Interstellar Silicate Analogs for Grain-surface Reaction Experiments: Gas-phase Condensation and Characterization of the Silicate Dust Grains  

NASA Astrophysics Data System (ADS)

Amorphous, astrophysically relevant silicates were prepared by laser ablation of siliceous targets and subsequent quenching of the evaporated atoms and clusters in a helium/oxygen gas atmosphere. The described gas-phase condensation method can be used to synthesize homogeneous and astrophysically relevant silicates with different compositions ranging from nonstoichiometric magnesium iron silicates to pyroxene- and olivine-type stoichiometry. Analytical tools have been used to characterize the morphology, composition, and spectral properties of the condensates. The nanometer-sized silicate condensates represent a new family of cosmic dust analogs that can generally be used for laboratory studies of cosmic processes related to condensation, processing, and destruction of cosmic dust in different astrophysical environments. The well-characterized silicates comprising amorphous Mg2SiO4 and Fe2SiO4, as well as the corresponding crystalline silicates forsterite and fayalite, produced by thermal annealing of the amorphous condensates, have been used as real grain surfaces for H2 formation experiments. A specifically developed ultra-high vacuum apparatus has been used for the investigation of molecule formation experiments. The results of these molecular formation experiments on differently structured Mg2SiO4 and Fe2SiO4 described in this paper will be the topic of the next paper of this series.

Sabri, T.; Gavilan, L.; Jäger, C.; Lemaire, J. L.; Vidali, G.; Mutschke, H.; Henning, T.

2014-01-01

261

46 CFR 154.1740 - Vinyl chloride: Inhibiting and inerting.  

Code of Federal Regulations, 2010 CFR

...FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Special Design and Operating Requirements § 154...met; or (b) Section 154.1710 is met, and the oxygen content of inert gas is less than 0.1% by...

2010-10-01

262

Formation of a molecular Bose-Einstein condensate and an entangled atomic gas by Feshbach resonance  

Microsoft Academic Search

Association in an atomic Bose-Einstein condensate, and dissociation of the resulting molecular condensate, due to a Feshbach resonance in a time-dependent magnetic field, are analyzed incorporating non-mean-field quantum corrections and inelastic collisions. Calculations for the Na atomic condensate demonstrate that there exist optimal conditions under which about 80% of the atomic population can be converted to a relatively long-lived molecular

V. A. Yurovsky; A. Ben-Reuven

2003-01-01

263

Astrophysical Lasers in Optical Fe II Lines in Gas Condensations near ? Carinae  

NASA Astrophysics Data System (ADS)

We report here on the discovery of laser action in the range 0.9-2 ?m in several spectral lines of Fe II, which are associated with transitions from ``pseudo-metastable'' states populated by spontaneous transitions from Ly? pumped Fe II levels. The intense Ly? radiation is formed in the HII region of gas condensations close to the star ? Car. The laser transitions form together with spontaneous transitions closed radiative cycles, one of which includes the extremely bright 2507/09 Å lines. This fact, together with an accidental mixing of energy levels, may provide an explanation of the abnormal intensities of these UV non-lasing lines. Using the complicated energy level diagram of Fe II we present those peculiar features, which are essential for the inverted population and laser effect: the pumping, the level mixing, and the ``bottle neck'' for spontaneous decay. The laser action is a new indicator of non-equilibrium and spatially non-homogeneous physical conditions as well as a high brightness temperature of Ly? in ejecta from eruptive stars. Such conditions are very difficult to probe by existing methods.

Johansson, S.; Letokhov, V. S.

2005-05-01

264

Mathematical simulation of natural gas condensation processes using the Peng-Robinson equation of state  

SciTech Connect

On the basis of its simplicity and the data obtained by a great number of tests and comparative analysis, the authors consider the Peng-Robinson (PR) equation of state to be the most suitable to calculate the condensation processes of natural gas, and further on to set up the equations of material and heat balances. In case of mixtures, the accuracy of the PR equation of state was mainly influenced by the correct selection of the interaction coefficients. The paper presents the calculation correlations of the thermal and thermodynamic properties published uncompletely before, as expressed with the parameters of the PR equation of state. Using the experiences obtained by the application of the PENG-ROBINSON AGA PROGRAM the authors have developed a module for calculation of phase equilibria and thermodynamic properties of fluid systems. This is the main module of their program MODEL-TECH (constructed in module structure) which is suitable to calculate separators, heat exchangers, heat sources, heat drains, Joule-Thomson effect, expansion turbines, compressors, detander-compressor units, arbitrary columns and simulation processes of any degree of complexity built from the above elements.

Nagy, Z.; Shirkovshiy, A.I.

1982-09-01

265

Studies on pressure response of gas bubbles contributions of condensed droplets in bubbles generated by a uniform nucleation  

NASA Technical Reports Server (NTRS)

The response of a tiny gas bubble under reduced pressure is investigated in its relation to cavitation. Equations of motion are formulated for gas mixtures inside the bubble and numerical calculations performed for several examples. The conclusions are as follows: (1) at the onset of bubble growth, the gas mixture inside it adiabatically expands and the temperature decreases. Condensed droplets appear inside the gas mixture due to a uniform nucleation and the temperature recovers, thus the motion of the bubble is apparently isothermal; (2) the evaporation and condensation coefficient largely affects bubble motions (maximum radius, period and rate of attenuation of the bubble oscillation) including the uniform contraction; (3) the oscillation period of the bubble is longer as the equilibrium bubble radius is larger when the surrounding pressure decreases stepwise. In this circumstance the temperature inside the bubble is kept constant due to condensation evaporation phenomena and is nearly isothermal; and (4) when the surrounding pressure decreases in a stepwise fashion, the critical pressure bubble radius relation becomes closer to that for the isothermal process if the bubble radius is larger than 8 microns.

Matsumoto, Y.

1988-01-01

266

Structure, particle size, and annealing of gas phase-condensed Eu 3+:Y 2O 3 nanophosphors  

NASA Astrophysics Data System (ADS)

This paper reports the phase distribution and particle size of Eu 3+:Y 2O 3 nanoparticles prepared by gas-phase condensation as a function of preparation conditions and annealing. Annealing improves the crystallinity of the as-prepared nanoparticles but also increases the particle size. Gas-phase condensation at a low pressure (10 Torr) produces 5-nm Eu 3+:Y 2O 3 in multiple phases. Annealing the 5-nm nanoparticles produces single-phase material in the cubic structure with a doubling of the particle size. Higher chamber pressures produce larger particles. A pressure of 400 Torr produces 13-nm Eu 3+:Y 2O 3 in the monoclinic structure. Annealing the 13-nm particles produces a mixture of monoclinic and cubic phase material with a 50% increase in average particle size. We also report preliminary attempts to disperse Eu 3+:Y 2O 3 and Eu 2O 3 nanoparticles in different surfactant and polymer solutions.

Tissue, B. M.; Yuan, H. B.

2003-02-01

267

Maxwell-Schroedinger equations for a dilute gas Bose-Einstein condensate coupled to an electromagnetic field  

SciTech Connect

We give a general formulation of the semiclassical approach to solving the problem of interaction between a Bose-Einstein condensate of dilute gas and electromagnetic radiation without using the commonly applied mean-field approximation. We suggest variants of the systems of Maxwell-Schroedinger equations whose solution describes such effects as superradiant light scattering, light beam amplification, atomic wave (atomic laser) amplification, induced transparency, and reduction in the group velocity of light.

Avetisyan, Yu. A. [Russian Academy of Sciences, Institute of Problems of Precise Mechanics and Control (Russian Federation); Trifonov, E. D. [Herzen Russian State Pedagogical University (Russian Federation)], E-mail: thphys@herzen.spb.ru

2008-03-15

268

Modelling and simulation of acid gas condensation in an industrial chimney - article no. A39  

SciTech Connect

Coal power stations as well as waste incinerators produce humid acid gases which may condense in industrial chimneys. These condensates can cause corrosion of chimney internal cladding which is made of stainless steel, nickel base alloys or non metallic materials. In the aim of polluting emission reduction and material optimal choice, it is necessary to determine and characterize all the phenomena which occur throughout the chimney and more especially condensation and dissolution of acid gases (in this particular case, sulfur dioxide SO{sub 2}).

Serris, E.; Cournil, M.M.; Peultier, J. [Ecole des Mines de St Etienne, St Etienne (France)

2009-07-01

269

A new gas-phase condensed mechanism of isoprene-NO x photooxidation  

NASA Astrophysics Data System (ADS)

A new condensed gas-phase isoprene mechanism is developed and evaluated, using O 3, nitrogen oxides (NO x), and volatile organic compounds (VOC) data from over twenty isoprene experiments. Experiments were performed in two UNC dual outdoor smog chambers using natural sunlight, with different NO x levels, and with or without the presence of an urban hydrocarbon environment. The mechanism uses the Carbon Bond mechanism (CB05) to represent inorganic chemistry and hydrocarbons other than isoprene. It was designed so that the chemistry related to secondary organic aerosol (SOA) formation can be incorporated, and thus it can be further expanded into a gas-aerosol-phase mechanism. A box model framework of this new isoprene mechanism is able to reasonably simulate most experimental data at HC/NO x ratios that range from 0.3 to 18. An intercomparison was performed between the isoprene kinetics developed in this study and other isoprene chemistry that is included in other kinetic mechanisms, including MCM v3.1, SAPRC99, SAPRC07, MIM2, CB4 and CB05. The results indicate that most current mechanisms tend to under-predict ozone levels to different extents, while the new mechanism simulates the UNC smog chamber O 3 data better than the others in most cases, especially at higher HC/NO x ratios. Further, the new mechanism performs reasonably well in modeling outdoor smog chamber experiments with isoprene in an urban hydrocarbon mixture. In addition, a HO x (OH + HO 2) recycling scheme based upon Peeters et al. (2009) and Archibald et al. (2010b) was implemented in MCM v3.1 and the new UNC mechanism, since it has been recently been suggested to be very important under low-NO x conditions. Although our experimental data base is very limited for the low-NO x condition, the Peeters et al. (2009) isoprene chemistry tended to significantly over-predict observed chamber O 3. This suggests that more low-NO x experiments and further confirmation of current theoretical studies are needed.

Zhang, Haofei; Rattanavaraha, Weruka; Zhou, Yang; Bapat, Jyoti; Rosen, Elias P.; Sexton, Kenneth G.; Kamens, Richard M.

2011-08-01

270

Non-condensible gas injection including alpha-olefin sulfonate dimer surfactant additives and a process of stimulating hydrocarbon recovery from a subterranean formation  

SciTech Connect

A non-condensible gas process is described of recovering hydrocarbons from a subterranean formation in the absence of steam, wherein the formation is penetrated by at least one injection well and at least one production well. The process consists of: (a) injecting a non-condensible gas and, including therewith and in the absence of steam, a sufficient amount of an alpha-olefin sulfonate dimer to form a non-condensible gas and alpha-olefin sulfonate dimer foam at an injection well; (b) continuing to inject the non-condensible gas and alpha-olefin sulfonate dimer foam to assist the movement of hydrocarbons toward the production well, and (c) recovering hydrocarbons from a production well.

Duerksen, J.H.; Wall, R.G.; Knight, J.D.

1986-03-18

271

Gasification Effects in the Heterogeneous Ignition of a Condensed Fuel by a Hot Gas.  

National Technical Information Service (NTIS)

An analysis is presented to describe the heterogeneous ignition of a condensed fuel suddenly exposed to a hot oxidizing atmosphere. The exothermic heterogeneous reaction, generating gaseous products, is considered to be of the Arrhenius type with an activ...

M. Kindelan A. Linan

1976-01-01

272

Macrokinetics of physicochemical condensation in two-phase systems of the gas-solid body type  

Microsoft Academic Search

The macrokinetics of the phase evolution at the microscopic level under isothermal and nonisothermal conditions is analyzed\\u000a theoretically within the framework of a two-scale approach for describing physicochemical condensation processes in two-phase\\u000a systems. Scenarios are established for the transformation of the condensed particles in a chemically active medium, taking\\u000a into account the exothermal nature of the reaction, the finiteness of

Yu. M. Grigor’ev; S. I. Doronin; I. A. Filimonov

1998-01-01

273

Photochemical activity of Titan's low-altitude condensed haze.  

PubMed

Titan, the largest moon of Saturn and similar to Earth in many aspects, has unique orange-yellow colour that comes from its atmospheric haze, whose formation and dynamics are far from well understood. Present models assume that Titan's tholin-like haze formation occurs high in atmosphere through gas-phase chemical reactions initiated by high-energy solar radiation. Here we address an important question: Is the lower atmosphere of Titan photochemically active or inert? We demonstrate that indeed tholin-like haze formation could occur on condensed aerosols throughout the atmospheric column of Titan. Detected in Titan's atmosphere, dicyanoacetylene (C?N?) is used in our laboratory simulations as a model system for other larger unsaturated condensing compounds. We show that C4N2 ices undergo condensed-phase photopolymerization (tholin formation) at wavelengths as long as 355 nm pertinent to solar radiation reaching a large portion of Titan's atmosphere, almost close to the surface. PMID:23552063

Gudipati, Murthy S; Jacovi, Ronen; Couturier-Tamburelli, Isabelle; Lignell, Antti; Allen, Mark

2013-01-01

274

Biodegradation of an Alicyclic Hydrocarbon by a Sulfate-Reducing Enrichment from a Gas Condensate-Contaminated Aquifer  

PubMed Central

We used ethylcyclopentane (ECP) as a model alicyclic hydrocarbon and investigated its metabolism by a sulfate-reducing bacterial enrichment obtained from a gas condensate-contaminated aquifer. The enrichment coupled the consumption of ECP with the stoichiometrically expected amount of sulfate reduced. During ECP biodegradation, we observed the transient accumulation of metabolite peaks by gas chromatography-mass spectrometry, three of which had identical mass spectrometry profiles. Mass-spectral similarities to analogous authentic standards allowed us to identify these metabolites as ethylcyclopentylsuccinic acids, ethylcyclopentylpropionic acid, ethylcyclopentylcarboxylic acid, and ethylsuccinic acid. Based on these findings, we propose a pathway for the degradation of this alicyclic hydrocarbon. Furthermore, a putative metabolite similar to ethylcyclopentylsuccinic acid was also found in samples of contaminated groundwater from the aquifer. However, no such finding was evident for samples collected from wells located upgradient of the gas condensate spill. Microbial community analysis of the ECP-degrading enrichment by denaturing gradient gel electrophoresis revealed the presence of at least three different organisms using universal eubacterial primers targeting 550 bp of the 16S rRNA gene. Based on sequence analysis, these organisms are phylogenetically related to the genera Syntrophobacter and Desulfotomaculum as well as a member of the Cytophaga-Flexibacter-Bacteroides group. The evidence suggests that alicyclic hydrocarbons such as ECP can be anaerobically activated by the addition to the double bond of fumarate to form alkylsuccinate derivatives under sulfate-reducing conditions and that the reaction occurs in the laboratory and in hydrocarbon-impacted environments.

Rios-Hernandez, Luis A.; Gieg, Lisa M.; Suflita, Joseph M.

2003-01-01

275

Cloud Condensation in Titan's Lower Stratosphere  

NASA Technical Reports Server (NTRS)

A 1-D condensation model is developed for the purpose of reproducing ice clouds in Titan's lower stratosphere observed by the Composite Infrared Spectrometer (CIRS) onboard Cassini. Hydrogen cyanide (HCN), cyanoacetylene (HC3N), and ethane (C2H6) vapors are treated as chemically inert gas species that flow from an upper boundary at 500 km to a condensation sink near Titan's tropopause (-45 km). Gas vertical profiles are determined from eddy mixing and a downward flux at the upper boundary. The condensation sink is based upon diffusive growth of the cloud particles and is proportional to the degree of supersaturation in the cloud formation regIOn. Observations of the vapor phase abundances above the condensation levels and the locations and properties of the ice clouds provide constraints on the free parameters in the model. Vapor phase abundances are determined from CIRS mid-IR observations, whereas cloud particle sizes, altitudes, and latitudinal distributions are derived from analyses of CIRS far-IR observations of Titan. Specific cloud constraints include: I) mean particle radii of2-3 J.lm inferred from the V6 506 cm- band of HC3N, 2) latitudinal abundance distributions of condensed nitriles, inferred from a composite emission feature that peaks at 160/cm , and 3) a possible hydrocarbon cloud layer at high latitudes, located near an altitude of 60 km, which peaks between 60 and 80 cm l . Nitrile abundances appear to diminish substantially at high northern latitudes over the time period 2005 to 2010 (northern mid winter to early spring). Use of multiple gas species provides a consistency check on the eddy mixing coefficient profile. The flux at the upper boundary is the net column chemical production from the upper atmosphere and provides a constraint on chemical pathways leading to the production of these compounds. Comparison of the differing lifetimes, vapor phase transport, vapor phase loss rate, and particle sedimentation, sheds light on temporal stability of the clouds.

Romani, Paul N.; Anderson, Carrie M.

2011-01-01

276

Direct synthesis of large size ferromagnetic SmCo5 nanoparticles by a gas-phase condensation method  

NASA Astrophysics Data System (ADS)

Ferromagnetic SmCo5 nanoparticles with large size have been directly synthesized by a magnetron-sputtering-based gas-phase condensation method. Based on this method, we studied the effect of thermodynamic environment for the growth of SmCo5 nanoparticles. It was found that the well-crystallized SmCo5 nanoparticle tends to form a hexagonal disk shape with its easy axis perpendicular to the disk plane. More importantly, under the condition of high sputtering current, well-crystallized nanoparticles were found to be formed through a three-stage growth process: aggregation, coalescence, and second crystallization.

He, Shihai; Jing, Ying; Wang, Jian-Ping

2013-04-01

277

Direct synthesis of large size ferromagnetic SmCo{sub 5} nanoparticles by a gas-phase condensation method  

SciTech Connect

Ferromagnetic SmCo{sub 5} nanoparticles with large size have been directly synthesized by a magnetron-sputtering-based gas-phase condensation method. Based on this method, we studied the effect of thermodynamic environment for the growth of SmCo{sub 5} nanoparticles. It was found that the well-crystallized SmCo{sub 5} nanoparticle tends to form a hexagonal disk shape with its easy axis perpendicular to the disk plane. More importantly, under the condition of high sputtering current, well-crystallized nanoparticles were found to be formed through a three-stage growth process: aggregation, coalescence, and second crystallization.

He Shihai; Jing Ying; Wang Jianping [Department of Electrical and Computer Engineering and Center for Micromagnetics and Information Technology (MINT), University of Minnesota, 200 Union St. SE, 4-174 EE/CSci, Minneapolis, Minnesota 55455 (United States)

2013-04-07

278

Simulation of basic gas mixing tests with condensation in the PANDA facility using the GOTHIC code  

Microsoft Academic Search

The paper reports the results of the assessment of the GOTHIC code using the data of four basic tests with condensation performed in the PANDA large-scale facility. Three of these experiments featured vertical injection, and in one the transient response due to a high-momentum horizontal injection (jet) was investigated. The injected fluid was either saturated steam or a superheated mixture

Michele Andreani; Domenico Paladino; Tom George

2010-01-01

279

Failure analysis of cooling water pipes used in the condensation system of a gas turbine  

Microsoft Academic Search

The copper–zinc alloy pipes used in the condensed water system of a power plant failed within a period of 5 to 6 years. Because the service life of such a system was expected to be on the order of 20 years, an investigation was carried out to determine the possible causes for early failure of the pipes. Visual inspection revealed that the

Havva Kazdal Zeytin

2008-01-01

280

AN INNOVATIVE TRANSPORT MEMBRANE CONDENSER WATER RECOVERY FROM FLUE GAS AND ITS REUSE - PHASE II  

EPA Science Inventory

Although water recycle and reuse is considered good environmental practice, its implementation is highly dependent upon the economics and hence can be challenging to implement. An example is the recovery of low quality heat as water condensate from industrial flue gases. In th...

281

Novel Numerical Techniques to Calculate the Ground and Excited States of an Anisotropically Confined Condensed Bose Gas  

NASA Astrophysics Data System (ADS)

The ground and excited states of a weakly interacting, dilute Bose gas confined in a harmonic oscillator potential are studied using a number of novel computational techniques which enable the authors to extend previous results to the completely anisotropic well and to condensates which have been difficult or impossible to study previously. The numerical calculations employ a discrete variable representation (DVR) based on either the Hermite or LaGrange interpolating polynomials which make it trivial to evaluate matrix elements of the nonlinear term in the Hamiltonian and in addition, lead to a sparse matrix representation. We have found that standard iterative techniques applied to the solution of these non-linear partial differential equations, particularly for large number of condensate atoms, are non-convergent. This limitation has been overcome using a variant of the method of the Direct Inversion in the Iterated Subspace (DIIS) and a novel use of of the multi-grid technique. In addition, the sparse structure of the DVR representation enables the efficient application of iterative techniques such as the Davidson and/or Lanczos methods, to extract the relevant eigenpairs. The results are compared with recent experimental data obtained for Bose-condensed alkali metal vapours confined in magnetic traps.

Schneider, Barry I.; Feder, David L.

1998-05-01

282

One-dimensional model of evaporation and condensation in the presence of a noncondensable gas with applications to cryogenic fluid storage  

Microsoft Academic Search

This paper considers the one-dimensional flow of vapor between two liquid surfaces due to evaporation and condensation taking into account diffusion through a noncondensable gas and nonequilibrium interfacial kinetics. An explicit relationship is developed for the mass flux J as a function of the characteristic mole ratio of noncondensable gas X, and several simplifications are made to arrive at an

Charles Panzarella; Mohammad Kassemi

2009-01-01

283

Synthesis of fluorinated nano-silica and its application in wettability alteration near-wellbore region in gas condensate reservoirs  

NASA Astrophysics Data System (ADS)

Fluorinated silica nanoparticles were prepared to alter rock wettability near-wellbore region in gas condensate reservoirs. Hence fluorinated silica nanoparticles with average diameter of about 80 nm were prepared and used to alter limestone core wettability from highly liquid-wet to intermediate gas-wet state. Water and n-decane contact angles for rock were measured before and after treatment. The contact angle measured 147° for water and 61° for n-decane on the core surface. The rock surface could not support the formation of any water or n-decane droplets before treatment. The functionalized fluorinated silica nanoparticles have been confirmed by the Csbnd F bond along with Sisbnd Osbnd Si bond as analyzed by FT-IR. The elemental composition of treated limestone core surface was determined using energy dispersive X-ray spectroscopy analyses. The final evaluation of the fluorinated nanosilica treatment in terms of its effectiveness was measured by core flood experimental tests.

Mousavi, M. A.; Hassanajili, Sh.; Rahimpour, M. R.

2013-05-01

284

Metallofullerene and fullerene formation from condensing carbon gas under conditions of stellar outflows and implication to stardust  

PubMed Central

Carbonaceous presolar grains of supernovae origin have long been isolated and are determined to be the carrier of anomalous 22Ne in ancient meteorites. That exotic 22Ne is, in fact, the decay isotope of relatively short-lived 22Na formed by explosive nucleosynthesis, and therefore, a selective and rapid Na physical trapping mechanism must take place during carbon condensation in supernova ejecta. Elucidation of the processes that trap Na and produce large carbon molecules should yield insight into carbon stardust enrichment and formation. Herein, we demonstrate that Na effectively nucleates formation of Na@C60 and other metallofullerenes during carbon condensation under highly energetic conditions in oxygen- and hydrogen-rich environments. Thus, fundamental carbon chemistry that leads to trapping of Na is revealed, and should be directly applicable to gas-phase chemistry involving stellar environments, such as supernova ejecta. The results indicate that, in addition to empty fullerenes, metallofullerenes should be constituents of stellar/circumstellar and interstellar space. In addition, gas-phase reactions of fullerenes with polycyclic aromatic hydrocarbons are investigated to probe “build-up” and formation of carbon stardust, and provide insight into fullerene astrochemistry.

Dunk, Paul W.; Adjizian, Jean-Joseph; Kaiser, Nathan K.; Quinn, John P.; Blakney, Gregory T.; Ewels, Christopher P.; Marshall, Alan G.; Kroto, Harold W.

2013-01-01

285

Metallofullerene and fullerene formation from condensing carbon gas under conditions of stellar outflows and implication to stardust.  

PubMed

Carbonaceous presolar grains of supernovae origin have long been isolated and are determined to be the carrier of anomalous (22)Ne in ancient meteorites. That exotic (22)Ne is, in fact, the decay isotope of relatively short-lived (22)Na formed by explosive nucleosynthesis, and therefore, a selective and rapid Na physical trapping mechanism must take place during carbon condensation in supernova ejecta. Elucidation of the processes that trap Na and produce large carbon molecules should yield insight into carbon stardust enrichment and formation. Herein, we demonstrate that Na effectively nucleates formation of Na@C60 and other metallofullerenes during carbon condensation under highly energetic conditions in oxygen- and hydrogen-rich environments. Thus, fundamental carbon chemistry that leads to trapping of Na is revealed, and should be directly applicable to gas-phase chemistry involving stellar environments, such as supernova ejecta. The results indicate that, in addition to empty fullerenes, metallofullerenes should be constituents of stellar/circumstellar and interstellar space. In addition, gas-phase reactions of fullerenes with polycyclic aromatic hydrocarbons are investigated to probe "build-up" and formation of carbon stardust, and provide insight into fullerene astrochemistry. PMID:24145444

Dunk, Paul W; Adjizian, Jean-Joseph; Kaiser, Nathan K; Quinn, John P; Blakney, Gregory T; Ewels, Christopher P; Marshall, Alan G; Kroto, Harold W

2013-11-01

286

Materials in Condensing Boilers.  

National Technical Information Service (NTIS)

This is a review of corrosion and materials problems in condensing boilers for oil and gas. In the condensing boiler the fluegas is cooled below the water dewpoint of 45-48sub(o)C with gasoil and 55-58sub(o)C with natural gas. Materials for the three zone...

P. Jansen

1985-01-01

287

Transient Thermometry with Inert Thermometers.  

National Technical Information Service (NTIS)

A thermometer in contact with a test specimen is inert, if its heat capacity is not small compared with the heat capacity of the test specimen. The response of the thermometer to a transient temperature of the specimen can then be described by a transfer ...

J. C. Erdmann J. A. Jahoda

1966-01-01

288

Dynamics of gas condensate removal from an Al-Fe-humus podzol and its effect on the complexes of soil fungi  

NASA Astrophysics Data System (ADS)

The time period for the removal of gas condensate from the cultivated and forest Al-Fe-humus podzols in the northwestern region of Russia was determined in an experiment. The content of the light fractions of oil decreased more slowly in the forest soil than in the cultivated soil due to the lower rates of evaporation and photochemical reactions under the forest canopy. During the first five days after applying the gas condensate, its content decreased by nearly 70% in the cultivated soils and by only 8% in the forest soil. In three months of the growing period, the gas condensate was completely removed from the cultivated soils and by 91% from the forest soil. The species composition and structure of the fungal communities significantly changed in the polluted soils with an increase in the portion of conventionally pathogenic fungi from 45% in the control soil to 60-70% in the polluted soil.

Evdokimova, G. A.; Korneikova, M. V.; Myazin, V. A.

2013-03-01

289

Bénard instabilities in a binary-liquid layer evaporating into an inert gas: Stability of quasi-stationary and time-dependent reference profiles  

NASA Astrophysics Data System (ADS)

This study treats an evaporating horizontal binary-liquid layer in contact with the air with an imposed transfer distance. The liquid is an aqueous solution of ethanol (10% wt). Due to evaporation, the ethanol mass fraction can change and a cooling occurs at the liquid-gas interface. This can trigger solutal and thermal Rayleigh-Bénard-Marangoni instabilities in the system, the modes of which corresponding to an undeformable interface form the subject of the present work. The decrease of the liquid-layer thickness is assumed to be slow on the diffusive time scales (quasi-stationarity). First we analyse the stability of quasi-stationary reference profiles for a model case within which the mass fraction of ethanol is assumed to be fixed at the bottom of the liquid. Then this consideration is generalized by letting the diffusive reference profile for the mass fraction in the liquid be transient (starting from a uniform state), while following the frozen-time approach for perturbations. The critical liquid thickness below which the system is stable at all times quite expectedly corresponds to the one obtained for the quasi-stationary profile. As a next step, a more realistic, zero-flux condition is used at the bottom in lieu of the fixed-concentration one. The critical thickness is found not to change much between these two cases. At larger thicknesses, the critical time at which the instability first appears proves, as can be expected, to be independent of the type of the concentration condition at the bottom. It is shown that solvent (water) evaporation plays a stabilizing role as compared to the case of a non-volatile solvent. At last, an effective approximate Pearson-like model is invoked making use in particular of the fact that the solutal Marangoni is by far the strongest as an instability mechanism here.

Machrafi, H.; Rednikov, A.; Colinet, P.; Dauby, P. C.

2011-02-01

290

Interferometry using adiabatic passage in dilute-gas Bose-Einstein condensates  

NASA Astrophysics Data System (ADS)

We theoretically examine three-well interferometry in Bose-Einstein condensates (BECs) using adiabatic passage. Specifically, we demonstrate that a fractional coherent transport adiabatic passage protocol enables stable spatial splitting in the presence of nonlinear interactions. A reversal of this protocol produces a coherent recombination of the BEC with a phase-dependent population of the three wells. The effect of nonlinear interactions on the interferometric measurement is quantified and is found to lead to an enhancement in sensitivity for moderate interaction strengths.

Rab, M.; Hayward, A. L. C.; Cole, J. H.; Greentree, A. D.; Martin, A. M.

2012-12-01

291

Bose-Einstein condensation of biexcitons in a two-dimensional electron gas  

NASA Astrophysics Data System (ADS)

Low temperature photoluminescence (PL) spectra from the recombination of degenerate quasi-two-dimensional electrons with localized photoexcited holes exhibit a Mahan exciton which undergoes abrupt fundamental changes when the electron density n = 1.9E-11 /cm squared.(P. Folkes et al. Phys. Rev. Lett. 71, 3379 (1993)) We observe an abrupt decrease in the exciton PL intensity and linewidth with the concomitant formation of biexcitons and a large discontinuity in the exciton groundstate energy. With increasing excitation intensity we observe PL spectra which strongly indicate the occurrence of Bose-Einstein condensation of biexcitons and verify recent theory on the radiative renormalization of biexcitons.

Folkes, P. A.; Shen, H.; Zhou, W.; Smith, D.; Dutta, M.; Taysing-Lara, M.; Newman, P.; Lemeune, M.

1996-03-01

292

Turbulent condensation on a cold wall in the presence of a noncondensable gas  

SciTech Connect

A condensation model for forced and natural convection is derived by extending the Reynolds-Colburn analogy for heat and momentum transfer to mass and momentum transfer. The model is compared to the steady-state data of Uchida and Tagami and found to be in reasonable agreement with the forced convection data when an imposed velocity of 2 m/s is assumed. The natural convection model has the same functional dependence on Grashof number (h /SUB tot/ aboutGr /SUP -0.37/ ) as the data of Akers.

Corradini, M.L.

1984-02-01

293

Effect of scenedesmus acuminatus green algae extracts on the development of Candida lipolytic yeast in gas condensate-containing media  

NASA Technical Reports Server (NTRS)

Data are given of a comparative study of the growth and development as well as the characteristics of the biomass of the C. Lipolytica yeast according to the content of raw protein, protein, lipids, vitamins in the B group, and residual hydrocarbons during growth in media with de-aromatized gas-condensate FNZ as the carbon source with aqueous and alcohol extracts of S. acuminatus as the biostimulants. It is shown that the decoction and aqueous extract of green algae has the most intensive stimulating effect on the yeast growth. When a decoction of algae is added to the medium, the content of residual hydrocarbons in the biomass of C. lipolytica yeast is reduced by 4%; the quantity of protein, lipids, thamine and inositol with replacement of the yeast autolysate by the decoction of algae is altered little.

Bilmes, B. I.; Kasymova, G. A.; Runov, V. I.; Karavayeva, N. N.

1980-01-01

294

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

295

SiO(x) nanoparticles synthesized by an evaporation and condensation process using induction melting of silicon and gas injection.  

PubMed

SiO(x) nanoparticles were synthesized using a specially designed induction melting system equipped with a segmented graphite crucible. The graphite crucible with the segmented wall was the key to enhancing the evaporation rate due to the increase of the evaporation area and convection of the silicon melt. Injection of the gas mixture of oxygen (O2) and argon (Ar) on silicon (Si) melt caused the formation of SiO(x) nanoparticles. The evaporated SiO(x) nanoparticles were then cooled and condensed in a process chamber. The effects of the O2/Ar ratio in the injection gas on the microstructures of the SiO(x) nanoparticles were then investigated. Synthesized SiO(x) nanoparticles were proven to be of a homogeneous amorphous phase with average diameters of 30-35 nm. The microstructures were independent from the O2/Ar ratio of the injected gas. However, x increased from 1.36 to 1.84 as the O2/Ar ratio increased. The purity of the synthesized nanoparticles was about 99.9%. SiO(x) nanoparticles could be applied as the active anode material in a lithium (Li) ion secondary battery. PMID:23858929

Jang, Bo Yun; Lee, Jin Seok; Kim, Joon Soo

2013-05-01

296

A facility for gas- and condensed-phase measurements behind shock waves  

Microsoft Academic Search

A shock-tube facility consisting of two, single-pulse shock tubes for the study of fundamental processes related to gas-phase chemical kinetics and the formation and reaction of solid and liquid aerosols at elevated temperatures is described. Recent upgrades and additions include a new high-vacuum system, a new gas-handling system, a new control system and electronics, an optimized velocity-detection scheme, a computer-based

Eric L Petersen; Matthew J A Rickard; Mark W Crofton; Erin D Abbey; Matthew J Traum; Danielle M Kalitan

2005-01-01

297

Inert anodes for aluminum smelting  

SciTech Connect

The use of nonconsumable or inert anodes for replacement of consumable carbon anodes in Hall electrolysis cells for the production of aluminum has been a technical and commercial goal of the aluminum industry for many decades. This report summarizes the technical success realized in the development of an inert anode that can be used to produce aluminum of acceptable metal purity in small scale Hall electrolysis cells. The inert anode material developed consists of a cermet composition containing the phases: copper, nickel ferrite and nickel oxide. This anode material has an electrical conductivity comparable to anode carbon used in Hall cells, i.e., 150 ohm {sup {minus}1}cm{sup {minus}1}. Metal purity of 99.5 percent aluminum has been produced using this material. The copper metal alloy present in the anode is not removed by anodic dissolution as does occur with cermet anodes containing a metallic nickel alloy. Solubility of the oxide phases in the cryolite electrolyte is reduced by: (1) saturated concentration of alumina, (2) high nickel oxide content in the NiO-NiFe{sub 2}O{sub 4} composition, (3) lowest possible cell operating temperature, (4) additions of alkaline or alkaline earth fluorides to the bath to reduce solubilities of the anode components, and (5) avoiding bath contaminants such as silica. Dissolution rate measurements indicate first-order kinetics and that the rate limiting step for dissolution is mass transport controlled. 105 refs., 234 figs., 73 tabs.

Weyand, J.D.; Ray, S.P.; Baker, F.W.; DeYoung, D.H.; Tarcy, G.P.

1986-02-01

298

Nonlinear Pressure Shifts of Rubidium in Inert Gases  

Microsoft Academic Search

Vapor-cell atomic frequency standards are based on the hyperfine (microwave) magnetic-resonance frequencies of optically pumped alkali-metal atoms in inert buffer gas. Through the hyperfine-shift interaction, buffer gas induces pressure shift and broadening in these microwave resonances. Previous work uncovered nonlinear dependence in the pressure shifts of ^87Rb and Cs atoms to the pressure of buffer gases Ar and Kr, but

Bart McGuyer; Yuan-Yu Jau; William Happer

2009-01-01

299

Developing a scalable inert gas ion thruster  

NASA Technical Reports Server (NTRS)

Analytical studies to identify and then design a high performance scalable ion thruster operating with either argon or xenon for use in large space systems are presented. The magnetoelectrostatic containment concept is selected for its efficient ion generation capabilities. The iterative nature of the bounding magnetic fields allows the designer to scale both the diameter and length, so that the thruster can be adapted to spacecraft growth over time. Three different thruster assemblies (conical, hexagonal and hemispherical) are evaluated for a 12 cm diameter thruster and performance mapping of the various thruster configurations shows that conical discharge chambers produce the most efficient discharge operation, achieving argon efficiencies of 50-80% mass utilization at 240-310 eV/ion and xenon efficiencies of 60-97% at 240-280 eV/ion. Preliminary testing of the large 30 cm thruster, using argon propellant, indicates a 35% improvement over the 12 cm thruster in mass utilization efficiency. Since initial performance is found to be better than projected, a larger 50 cm thruster is already in the development stage.

James, E.; Ramsey, W.; Steiner, G.

1982-01-01

300

Sampling and Analysis Procedures for Gas, Condensate, Brine, and Solids: Pleasant Bayou Well Test, 1988-Present  

SciTech Connect

This section covers analyses performed on gas. Chemical analyses can only be related to well performance if the quantity of the various fluids are known. The IGT on-line data computer system measures the flowrate, the pressures, and the temperatures every 10 seconds. These values are automatically recorded over operator selected intervals both on magnetic media and on paper. This allows review of samples versus operating conditions. This paper covers analyses performed on gas, including: An approximate sampling schedule during flow tests; On-site sample handling and storage of gas samples; Addresses of laboratories that perform off site analyses; Sample shipping instructions; Data archiving; and Quality Control/Quality Assurance. It is expected that the above procedures will change as the flow test progresses, but deviations from the written procedures should be approved by C. Hayden of IGT and noted on the results of the analysis.

Hayden, Chris

1988-01-01

301

Prediction of the condensation behavior of natural gas: A comparative study of the Peng-Robinson and the simplified-perturbed-hard-chain theory equations of state  

Microsoft Academic Search

For the prediction of the condensation behavior of natural gas, one has to select an equation of state (EoS) which will be accurate in the temperature and pressure range of interest (10 < P\\/bar < 70 bar and 250 < T\\/K < 310). Another requirement of the selected EoS is that is easily can be adapted to a characterization procedure

Marianna E. Voulgaris; Cor J. Peters; Jakob de Swaan Arons

1998-01-01

302

Investigations in the Carcinogenicity of Diesel-Engine Exhaust-Gas Condensate and with sub-Fractions Implanted into the Lungs of Rats.  

National Technical Information Service (NTIS)

The test for the carcinogenetic effect of the hydrophilic fraction (approx. = 25% by weight) and the hydrophobic fraction (approx. = 75% by weight) of the diesel exhaust gas condensate and of sub-fractions of the hydrophobic part was carried through in th...

R. Deutsch-Wenzel H. Brune

1987-01-01

303

A compact setup to study homogeneous nucleation and condensation  

NASA Astrophysics Data System (ADS)

An experiment is presented to study homogeneous nucleation and the subsequent droplet growth at high temperatures and high pressures in a compact setup that does not use moving parts. Nucleation and condensation are induced in an adiabatic, stationary expansion of the vapor and an inert carrier gas through a Laval nozzle. The adiabatic expansion is driven against atmospheric pressure by pressurized inert gas its mass flow carefully controlled. This allows us to avoid large pumps or vacuum storage tanks. Because we eventually want to study the homogeneous nucleation and condensation of zinc, the use of carefully chosen materials is required that can withstand pressures of up to 106 Pa resulting from mass flow rates of up to 600 lN min-1 and temperatures up to 1200 K in the presence of highly corrosive zinc vapor. To observe the formation of droplets a laser beam propagates along the axis of the nozzle and the light scattered by the droplets is detected perpendicularly to the nozzle axis. An ICCD camera allows to record the scattered light through fused silica windows in the diverging part of the nozzle spatially resolved and to detect nucleation and condensation coherently in a single exposure. For the data analysis, a model is needed to describe the isentropic core part of the flow along the nozzle axis. The model must incorporate the laws of fluid dynamics, the nucleation and condensation process, and has to predict the size distribution of the particles created (PSD) at every position along the nozzle axis. Assuming Rayleigh scattering, the intensity of the scattered light can then be calculated from the second moment of the PSD.

Karlsson, Mattias; Alxneit, Ivo; Rütten, Frederik; Wuillemin, Daniel; Tschudi, Hans Rudolf

2007-03-01

304

A compact setup to study homogeneous nucleation and condensation.  

PubMed

An experiment is presented to study homogeneous nucleation and the subsequent droplet growth at high temperatures and high pressures in a compact setup that does not use moving parts. Nucleation and condensation are induced in an adiabatic, stationary expansion of the vapor and an inert carrier gas through a Laval nozzle. The adiabatic expansion is driven against atmospheric pressure by pressurized inert gas its mass flow carefully controlled. This allows us to avoid large pumps or vacuum storage tanks. Because we eventually want to study the homogeneous nucleation and condensation of zinc, the use of carefully chosen materials is required that can withstand pressures of up to 10(6) Pa resulting from mass flow rates of up to 600 l(N) min(-1) and temperatures up to 1200 K in the presence of highly corrosive zinc vapor. To observe the formation of droplets a laser beam propagates along the axis of the nozzle and the light scattered by the droplets is detected perpendicularly to the nozzle axis. An ICCD camera allows to record the scattered light through fused silica windows in the diverging part of the nozzle spatially resolved and to detect nucleation and condensation coherently in a single exposure. For the data analysis, a model is needed to describe the isentropic core part of the flow along the nozzle axis. The model must incorporate the laws of fluid dynamics, the nucleation and condensation process, and has to predict the size distribution of the particles created (PSD) at every position along the nozzle axis. Assuming Rayleigh scattering, the intensity of the scattered light can then be calculated from the second moment of the PSD. PMID:17411197

Karlsson, Mattias; Alxneit, Ivo; Rütten, Frederik; Wuillemin, Daniel; Tschudi, Hans Rudolf

2007-03-01

305

Methane microseepage from different sectors of the Yakela condensed gas field in Tarim Basin, Xinjiang, China  

Microsoft Academic Search

Methane microseepage is the result of natural gas migration from subsurface hydrocarbon accumulations to the Earth’s surface, and it is quite common in commercial petroleum fields. While the role of microseepage as a pathfinder in petroleum exploration has been known for about 80a, its significance as an atmospheric CH4 source has only recently been studied, and flux data are currently

Junhong Tang; Haoyong Yin; Guojian Wang; Yueyuan Chen

2010-01-01

306

Sampling and Analysis Procedures for Gas, Condensate, Brine, and Solids: Pleasant Bayou Well Test, 1988Present  

Microsoft Academic Search

This section covers analyses performed on gas. Chemical analyses can only be related to well performance if the quantity of the various fluids are known. The IGT on-line data computer system measures the flowrate, the pressures, and the temperatures every 10 seconds. These values are automatically recorded over operator selected intervals both on magnetic media and on paper. This allows

Hayden

1988-01-01

307

Bose-Einstein condensation temperature of a trapped interacting Bose-Fermi gas mixture  

Microsoft Academic Search

We calculate the critical temperature of a trapped interacting Bose-Fermi gas mixture by means of a first-order perturbation method in a local-density approximation. An explicit analytical expression is derived for the dependence of the critical temperature on the numbers of bosons and fermions, the strengths of boson-boson and boson-fermion interactions, and the trapping frequencies.

Yong-Li Ma; Siu-Tat Chui

2002-01-01

308

The triality of electromagnetic-condensational waves in a gas-like ether  

Microsoft Academic Search

In a gas-like ether, the duality between the oscillating electric and magnetic fields, which are transverse to the direction of propagation of electromagnetic waves, becomes a triality with the longitudinal oscillations of motion of the ether, if electric field, magnetic field and motion are coexistent and mutually perpendicular. It must be shown, therefore, that if electromagnetic waves comprise also longitudinal

C. K. Thornhill

309

AN INNOVATIVE TRANSPORT MEMBRANE CONDENSER FOR WATER RECOVERY FROM GAS AND ITS REUSE - PHASE I  

EPA Science Inventory

Although water recycle and reuse is considered good environmental practice, its implementation is highly dependent on the economics and hence can be challenging to implement. In this project, we present a unique opportunity to recover both water and energy from boiler flue gas...

310

Stardust: Studies in microgravity of condensation and agglomeration of cosmic dust analogue  

NASA Technical Reports Server (NTRS)

A short description of the program Stardust whose goal is to study the formation and properties of high temperature particles and gases, including silicate and carbonaceous materials, that are of interest in astrophysics and planetary science, is given. The international program was carried out in microgravity conditions in parabolic flight. A description of the laboratory equipment, conceived to perform experimental tests in reduced gravity conditions, and which is based on the gas evaporation technique, is given. The gas evaporation technique utilizes one or more heated crucible to vaporize solids materials (SiO, Mg) in a low pressure of inert or reactive gas inside of a vacuum bell jar. The vapor pressures of the materials are controlled by the temperature of the crucibles. The temperature and pressure of inert gas are also controlled. By varying the vapor pressure relative to the gas temperature and pressure, the conditions for substantial grain condensation can be controlled and grain formation measured using light scattering techniques. Thus the partial pressure for grain condensation, can be measured as a function of temperature. The gas evaporation technique has the advantage that complex chemical systems can be studied by using multiple crucibles each containing solid source material. Experimental results and future trends are addressed.

Ferguson, F.; Lilleleht, L. U.; Nuth, J.; Stephens, J. R.; Bussoletti, E.; Carotenuto, L.; Colangeli, L.; Dellaversana, P.; Mele, F.; Mennella, V.

1992-01-01

311

Interactions of Inert Confiners with Explosives  

Microsoft Academic Search

The deformation of an inert confiner by a steady detonation wave in an adjacent explosive is investigated for cases where\\u000a the confiner is sufficiently strong (or the explosive sufficiently weak) such that the overall change in the sound speed of\\u000a the inert is small. A coupling condition which relates the pressure to the deflection angle along the explosive-inert interface\\u000a is

G. J. Sharpe; J. B. Bdzil

2006-01-01

312

Macromolecular ensembles of cyclodextrin crystallohydrates and clathrates--experimental and theoretical gas--and condense phase study.  

PubMed

The paper reported a joined mass spectrometric, crystallographic and quantum chemical study of crystallohydrates, emphasizing on clathrates of native ?-, and ?-cyclodextrins as well as their randomly acetylated derivatives (4 and 5). The physical data are compared with 19 crystals of CDs, three of which new ones, differed by number of crystallohydrate (and/or clathrate) molecules (n)). The macroscopic complex CDs/n stability (n? [0.60-12.26]) is evaluated theoretically, accounting the surface and clathrate self-assembly of non-covalent hydrogen bonding interactions. The variety of competitive condensation processes of randomly acetylated products and the non-specific phase transition adduct of CDs and aggregates, which complicated significantly the MS picture are discussed. The single crystal X-ray diffraction, enable to determine the non-covalent interactions in CDs crystals, which physical phenomena in the gas-phase and crystalline phase ? liquid phase ? GP and CP ? GP transitions are evidenced mass spectrometrically. The quantum chemical method provided important thermodynamics and structural information at variety of states, allowing understanding comprehensively the complex GP phenomena. Special emphasis in the paper content is dedicated to the phenomenology of the GP mass spectrometric ionization processes and thermodynamics of fragmentation molecular ions of CDs and their supramolecular self-assembly which, strongly depends on the experimental factors. PMID:24370472

Ivanova, Bojidarka; Spiteller, Michael

2014-03-01

313

Cement solidification of simulated off-gas condensates from vitrification of low-level nuclear waste solutions.  

PubMed

Solidification in a cementitious matrix is a viable alternative for low-level nuclear waste management; it is therefore important to understand the behavior and properties of such wasteforms. We have examined the cementitious solidification of simulated off-gas waste streams resulting from the vitrification of low-level nuclear waste. Different possible methods for scrubbing the off-gasses from a vitrifier give rise to three possible types of waste compositions: acidic (from aqueous dissolution of volatile NOx and POx carried over from the vitrifier), basic (from neutralizing the former with sodium hydroxide), and fully carbonated (arising from a direct-combustion vitrifier). Six binder compositions were tested in which ordinary Portland cement was replaced at different proportions by fly ash and/or ground granulated blast furnace slag. A high solution to binder ratio of 1l/1 kg was used to minimize the volume of the wasteform and 10% attapulgite clay was added to all mixes to ensure that the fresh mix did not segregate prior to setting. The 28-day compressive strengths decreased when a high proportion of cement was replaced with fly ash, but were increased significantly when the cement was replaced with slag. The heats of hydration at early age for the various solids compositions decreased when cement was replaced with either fly ash or slag; however, for the fly ash mix the low heat was also associated with a significant decrease in compressive strength. High curing temperature (60 degrees C) or the use of extra-fine slag did not significantly affect the compressive strength. Recommendations for choice of binder formulations and treatment of off-gas condensates are discussed. PMID:11478621

Katz, A; Brough, A R; Kirkpatrick, R J; Struble, L J; Sun, G K; Young, J F

2001-01-01

314

Method for removing metal vapor from gas streams  

DOEpatents

A process for cleaning an inert gas contaminated with a metallic vapor, such as cadmium, involves withdrawing gas containing the metallic contaminant from a gas atmosphere of high purity argon; passing the gas containing the metallic contaminant to a mass transfer unit having a plurality of hot gas channels separated by a plurality of coolant gas channels; cooling the contaminated gas as it flows upward through the mass transfer unit to cause contaminated gas vapor to condense on the gas channel walls; regenerating the gas channels of the mass transfer unit; and, returning the cleaned gas to the gas atmosphere of high purity argon. The condensing of the contaminant-containing vapor occurs while suppressing contaminant particulate formation, and is promoted by providing a sufficient amount of surface area in the mass transfer unit to cause the vapor to condense and relieve supersaturation buildup such that contaminant particulates are not formed. Condensation of the contaminant is prevented on supply and return lines in which the contaminant containing gas is withdrawn and returned from and to the electrorefiner and mass transfer unit by heating and insulating the supply and return lines. 13 figs.

Ahluwalia, R.K.; Im, K.H.

1996-04-02

315

Method for removing metal vapor from gas streams  

DOEpatents

A process for cleaning an inert gas contaminated with a metallic vapor, such as cadmium, involves withdrawing gas containing the metallic contaminant from a gas atmosphere of high purity argon; passing the gas containing the metallic contaminant to a mass transfer unit having a plurality of hot gas channels separated by a plurality of coolant gas channels; cooling the contaminated gas as it flows upward through the mass transfer unit to cause contaminated gas vapor to condense on the gas channel walls; regenerating the gas channels of the mass transfer unit; and, returning the cleaned gas to the gas atmosphere of high purity argon. The condensing of the contaminant-containing vapor occurs while suppressing contaminant particulate formation, and is promoted by providing a sufficient amount of surface area in the mass transfer unit to cause the vapor to condense and relieve supersaturation buildup such that contaminant particulates are not formed. Condensation of the contaminant is prevented on supply and return lines in which the contaminant containing gas is withdrawn and returned from and to the electrorefiner and mass transfer unit by heating and insulating the supply and return lines.

Ahluwalia, R. K. (6440 Hillcrest Dr., Burr Ridge, IL 60521); Im, K. H. (925 Lehigh Cir., Naperville, IL 60565)

1996-01-01

316

Flammability limits of dusts: Minimum inerting concentrations  

SciTech Connect

A new flammability limit parameter has been defined as the Minimum Inerting Concentration (MIC). This is the concentration of inertant required to prevent a dust explosion regardless of fuel concentration. Previous experimental work at Fike in a 1-m{sup 3} spherical chamber has shown this flammability limit to exist for pulverized coal dust and cornstarch. In the current work, inerting experiments with aluminum, anthraquinone and polyethylene dusts as fuels were performed, using monoammonium phosphate and sodium bicarbonate as inertants. The results show that an MIC exists only for anthraquinone inerted with sodium bicarbonate. The other combustible dust and inertant mixtures did not show a definitive MIC, although they did show a strong dependence between inerting level and suspended fuel concentration. As the fuel concentration increased, the amount of inertant required to prevent an explosion decreased. Even though a definitive MIC was not found for most of the dusts an effective MIC can be estimated from the data. The use of MIC data can aid in the design of explosion suppression schemes.

Dastidar, A.G.; Amyotte, P.R. [Dalhousie Univ., Halifax, Nova Scotia (Canada). Dept. of Chemical Engineering] [Dalhousie Univ., Halifax, Nova Scotia (Canada). Dept. of Chemical Engineering; Going, J.; Chatrathi, K. [Fike Corp., Blue Springs, MO (United States)] [Fike Corp., Blue Springs, MO (United States)

1999-05-01

317

Contribution of polycyclic aromatic hydrocarbons and polar polycyclic aromatic compounds to the carcinogenic impact of flue gas condensate from coal-fired residential furnaces evaluated by implantation into the rat lung  

Microsoft Academic Search

For identification of the substances chiefly responsible for the carcinogenic action of the emission condensate from coal-fired residential furnaces, the implantation method was used as a carcinogen-specific bioassay for comparison of the carcinogenic effect of various fractions with that of a total sample of flue gas condensate tested in 2 or 3 different doses. After implantation into the lungs of

G. Grimmer; H. Brune; R. Deutsch-Wenzel; G. Dettbarn; J. Misfeld

1987-01-01

318

Bose-Einstein condensation temperature of a homogeneous weakly interacting Bose gas: Path integral Monte Carlo study  

SciTech Connect

Using a finite-temperature path integral Monte Carlo simulation (PIMC) method and finite-size scaling, we have investigated the interaction-induced shift of the phase-transition temperature for Bose-Einstein condensation of homogeneous weakly interacting Bose gases in three dimensions, which is given by a proposed analytical expression T{sub c}=T{sub c}{sup 0}{l_brace}1+c{sub 1}an{sup 1/3}+[c{sub 2}{sup '} ln(an{sup 1/3})+c{sub 2}]a{sup 2}n{sup 2/3}+O(a{sup 3}n){r_brace}, where T{sub c}{sup 0} is the critical temperature for an ideal gas, a is the s-wave scattering length, and n is the number density. We have used smaller number densities and more time slices than in the previous PIMC simulations [Gruter et al., Phys. Rev. Lett. 79, 3549 (1997)] in order to understand the difference in the value of the coefficient c{sub 1} between their results and the (apparently) other reliable results in the literature. Our results show that {l_brace}(T{sub c}-T{sub c}{sup 0})/T{sub c}{sup 0}{r_brace}/(an{sup 1/3}) depends strongly on the interaction strength an{sup 1/3} while the previous PIMC results are considerably flatter and smaller than our results. We obtain c{sub 1}=1.32{+-}0.14, in agreement with results from recent Monte Carlo methods of three-dimensional O(2) scalar {phi}{sup 4} field theory and variational perturbation theory.

Nho, Kwangsik; Landau, D.P. [Center for Simulational Physics, University of Georgia, Athens, Georgia 30602 (United States)

2004-11-01

319

A dynamic inert metal anode.  

SciTech Connect

A new concept for a stable anode for aluminum electrowinning is described. The anode consists of a cup-shaped metal alloy container filled with a molten salt that contains dissolved aluminum. The metal alloy can be any of a number of alloys, but it must contain aluminum as a secondary alloying metal. A possible alloy composition is copper with 5 to 15 weight percent aluminum. In the presence of oxygen, aluminum on the metal anode's exterior surface forms a continuous alumina film that is thick enough to protect the anode from chemical attack by cryolite during electrolysis and thin enough to maintain electrical conductivity. However, the alumina film is soluble in cryolite, so it must be regenerated in situ. Film regeneration is achieved by the transport of aluminum metal from the anode's molten salt interior through the metal wall to the anode's exterior surface, where the transported aluminum oxidizes to alumina in the presence of evolving oxygen to maintain the protective alumina film. Periodic addition of aluminum metal to the anode's interior keeps the aluminum activity in the molten salt at the desired level. This concept for an inert anode is viable as long as the amount of aluminum produced at the cathode greatly exceeds the amount of aluminum required to maintain the anode's protective film.

Hryn, J. N.

1998-11-09

320

Inert matrix fuel behaviour in test irradiations  

NASA Astrophysics Data System (ADS)

Among others, three large irradiation tests on inert matrix fuels have been performed during the last five years: the two irradiation tests IFA-651 and IFA-652 in the OECD Halden Material Test Reactor and the OTTO irradiation in the High Flux Reactor in Petten. While the OTTO irradiation is already completed, the other two irradiations are still ongoing. The objectives of the experiments differ: for OTTO, the focus was on the comparison of different concepts of IMF, i.e. homogeneous fuel versus different types of heterogeneous fuel. In IFA-651, single phase yttria stabilized zirconia (YSZ) doped with Pu is compared with MOX. In IFA-652, the potential of calcia stabilized zirconia (CSZ) as a matrix with and without thoria is evaluated. The design of the three experiments is explained and the current status is reviewed. The experiments show that the homogeneous, single phase YSZ-based or CSZ-based fuel show good and stable irradiation behaviour. It can be said that homogeneous stabilized zirconia based fuel is the most promising IMF concept for an LWR environment. Nevertheless, the fuel temperatures were relatively high due to the low thermal conductivity, potentially leading to high fission gas release, and must be taken into account in the fuel design.

Hellwig, Ch.; Streit, M.; Blair, P.; Tverberg, T.; Klaassen, F. C.; Schram, R. P. C.; Vettraino, F.; Yamashita, T.

2006-06-01

321

Latest advances in the understanding of acid dewpoint corrosion: corrosion and stress corrosion cracking in combustion gas condensates  

Microsoft Academic Search

Corrosion failures due to condensing flue gases containing H2O, SO3, NOx and HCl still occur more often than might be expected. The corrosion failures can be of several types: general corrosion, pitting attack and stress corrosion cracking (SCC). The chemistry of condensing gases is discussed, and some examples of corrosion in large-scale installations are presented, including blast stoves for steel

W. M. M. Huijbregts; R. G. I. Leferink

2004-01-01

322

Kinetic multi-layer model of gas-particle interactions in aerosols and clouds (KM-GAP): linking condensation, evaporation and chemical reactions of organics, oxidants and water  

NASA Astrophysics Data System (ADS)

We present a novel kinetic multi-layer model for gas-particle interactions in aerosols and clouds (KM-GAP) that treats explicitly all steps of mass transport and chemical reaction of semi-volatile species partitioning between gas phase, particle surface and particle bulk. KM-GAP is based on the PRA model framework (Pöschl-Rudich-Ammann, 2007), and it includes gas phase diffusion, reversible adsorption, surface reactions, bulk diffusion and reaction, as well as condensation, evaporation and heat transfer. The size change of atmospheric particles and the temporal evolution and spatial profile of the concentration of individual chemical species can be modeled along with gas uptake and accommodation coefficients. Depending on the complexity of the investigated system and the computational constraints, unlimited numbers of semi-volatile species, chemical reactions, and physical processes can be treated, and the model shall help to bridge gaps in the understanding and quantification of multiphase chemistry and microphysics in atmospheric aerosols and clouds. In this study we demonstrate how KM-GAP can be used to analyze, interpret and design experimental investigations of changes in particle size and chemical composition in response to condensation, evaporation, and chemical reaction. For the condensational growth of water droplets, our kinetic model results provide a direct link between laboratory observations and molecular dynamic simulations, confirming that the accommodation coefficient of water at ~270 K is close to unity (Winkler et al., 2006). Literature data on the evaporation of dioctyl phthalate as a function of particle size and time can be reproduced, and the model results suggest that changes in the experimental conditions like aerosol particle concentration and chamber geometry may influence the evaporation kinetics and can be optimized for efficient probing of specific physical effects and parameters. With regard to oxidative aging of organic aerosol particles, we illustrate how the formation and evaporation of volatile reaction products like nonanal can cause a decrease in the size of oleic acid particles exposed to ozone.

Shiraiwa, M.; Pfrang, C.; Koop, T.; Pöschl, U.

2012-03-01

323

Relation between biomarkers in exhaled breath condensate and internal exposure to metals from gas metal arc welding.  

PubMed

Concerning possible harmful components of welding fumes, besides gases and quantitative aspects of the respirable welding fumes, particle-inherent metal toxicity has to be considered.The objective of this study was to investigate the effect markers leukotriene B4 (LTB4),prostaglandin E2 (PGE2) and 8-isoprostane (8-Iso PGF2?) as well as the acid–base balance(pH) in exhaled breath condensate (EBC) of 43 full-time gas metal arc welders (20 smokers) in relation to welding fume exposure. We observed different patterns of iron, chromium and nickel in respirable welding fumes and EBC. Welders with undetectable chromium in EBC(group A, n = 24) presented high iron and nickel concentrations. In this group, higher 8-isoPGF2? and LTB4 concentrations could be revealed compared to welders with detectable chromium and low levels of both iron and nickel in EBC (group B): 8-iso PGF2?443.3 pg mL?1 versus 247.2 pg mL?1; p = 0.001 and LTB4 30.5 pg mL?1 versus 17.3 pgmL?1; p = 0.016. EBC-pH was more acid in samples of group B (6.52 versus 6.82; p = 0.011).Overall, effect markers in welders were associated with iron concentrations in EBC according to smoking habits--non-smokers/smokers: LTB4 (rs = 0.48; p = 0.02/rs = 0.21; p = 0.37),PGE2 (rs = 0.15; p = 0.59/rs = 0.47; p = 0.07), 8-iso PGF2? (rs = 0.18; p = 0.54/rs = 0.59;p = 0.06). Sampling of EBC in occupational research provides a matrix for the simultaneous monitoring of metal exposure and effects on target level. Our results suggest irritative effects in the airways of healthy welders. Further studies are necessary to assess whether these individual results might be used to identify welders at elevated risk for developing a respiratory disease. PMID:22622358

Hoffmeyer, Frank; Raulf-Heimsoth, Monika; Weiss, Tobias; Lehnert, Martin; Gawrych, Katarzyna; Kendzia, Benjamin; Harth, Volker; Henry, Jana; Pesch, Beate; Brüning, Thomas

2012-06-01

324

Propagation of first and second sound in a highly elongated trapped Bose-condensed gas at finite temperatures  

NASA Astrophysics Data System (ADS)

We study sound propagation in Bose-condensed gases in a highly elongated harmonic trap at finite temperatures. This problem is studied within the framework of the Zaremba-Nikuni-Griffin (ZNG) formalism, which consists of a generalized Gross-Pitaevskii equation for the condensate and a kinetic equation for the thermal cloud. We extend the ZNG formalism to deal with a highly anisotropic trap potential and use it to simulate sound propagation using the trap parameters corresponding to an experiment on sound pulse propagation at finite temperature. We focus on the high-density two-fluid hydrodynamic regime, and explore the possibility of observing first- and second-sound pulse propagation. The results of numerical simulation are compared with analytical results derived from linearized ZNG hydrodynamic equations. We show that the second-sound mode makes the dominant contribution to condensate motion at relatively high temperature, while the first-sound mode makes an appreciable contribution.

Arahata, Emiko; Nikuni, Tetsuro

2013-03-01

325

Isentropic Compression of Multicomponent Mixtures of Fuels and Inert Gases  

NASA Technical Reports Server (NTRS)

In selected aerospace applications of the fuels hydrazine and monomethythydrazine, there occur conditions which can result in the isentropic compression of a multicomponent mixture of fuel and inert gas. One such example is when a driver gas such as helium comes out of solution and mixes with the fuel vapor, which is being compressed. A second example is when product gas from an energetic device mixes with the fuel vapor which is being compressed. Thermodynamic analysis has shown that under isentropic compression, the fuels hydrazine and monomethylhydrazine must be treated as real fluids using appropriate equations of state. The appropriate equations of state are the Peng-Robinson equation of state for hydrazine and the Redlich-Kwong-Soave equation of state for monomethylhydrazine. The addition of an inert gas of variable quantity and input temperature and pressure to the fuel compounds the problem for safety design or analysis. This work provides the appropriate thermodynamic analysis of isentropic compression of the two examples cited. In addition to an entropy balance describing the change of state, an enthalpy balance is required. The presence of multicomponents in the system requires that appropriate mixing rules are identified and applied to the analysis. This analysis is not currently available.

Barragan, Michelle; Julien, Howard L.; Woods, Stephen S.; Wilson, D. Bruce; Saulsberry, Regor L.

2000-01-01

326

Bose-Einstein condensation temperature of a homogeneous weakly interacting Bose gas: Path integral Monte Carlo study  

Microsoft Academic Search

Using a finite-temperature path integral Monte Carlo simulation (PIMC) method and finite-size scaling, we have investigated the interaction-induced shift of the phase-transition temperature for Bose-Einstein condensation of homogeneous weakly interacting Bose gases in three dimensions, which is given by a proposed analytical expression Tc=Tc0{1+c1an1\\/3+[c2'ln(an1\\/3)+c2\\

Kwangsik Nho; D. P. Landau

2004-01-01

327

Effect of precursor supply on structural and morphological characteristics of fe nanomaterials synthesized via chemical vapor condensation method.  

PubMed

Various physical, chemical and mechanical methods, such as inert gas condensation, chemical vapor condensation, sol-gel, pulsed wire evaporation, evaporation technique, and mechanical alloying, have been used to synthesize nanoparticles. Among them, chemical vapor condensation (CVC) has the benefit of its applicability to almost all materials because a wide range of precursors are available for large-scale production with a non-agglomerated state. In this work, Fe nanoparticles and nanowires were synthesized by chemical vapor condensation method using iron pentacarbonyl (Fe(CO)5) as the precursor. The effect of processing parameters on the microstructure, size and morphology of Fe nanoparticles and nanowires were studied. In particular, we investigated close correlation of size and morphology of Fe nanoparticles and nanowires with atomic quantity of inflow precursor into the electric furnace as the quantitative analysis. The atomic quantity was calculated by Boyle's ideal gas law. The Fe nanoparticles and nanowires with various diameter and morphology have successfully been synthesized by the chemical vapor condensation method. PMID:22524015

Ha, Jong-Keun; Ahn, Hyo-Jun; Kim, Ki-Won; Nam, Tae-Hyun; Cho, Kwon-Koo

2012-01-01

328

Live and Inert Fascine Streambank Erosion Control.  

National Technical Information Service (NTIS)

Live fascines (LF) and inert fascines (IF) are sausage-shaped bundle structures made from cuttings of living woody plant material. In the LF, the cut branches are expected to grow producing roots and top growth, (performing additional soil reinforcement v...

R. B. Sotir C. Fischenich

2001-01-01

329

Design of scrubbers for condensing boilers  

Microsoft Academic Search

Many fuels (oil, wood or process gases) contain components which can be found as acid-forming compounds in the flue gas after combustion and which are absorbed to a small degree in the condensate when the dew point is reached. This acid, and therefore highly corrosive condensate, increases the demands on the materials used for the areas affected by condensation in

F. Haase; H. Koehne

1999-01-01

330

Diamondoid Characterization in Condensate by Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometry: The Junggar Basin of Northwest China.  

PubMed

Diamondoids in crude oil are useful for assessing the maturity of oil in high maturation. However, they are very difficult to separate and accurately quantify by conventional geochemical methods due to their low abundance in oil. In this paper, we use comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) to study the compounds in condensates from the Junggar Basin of northwest China and address their geological and geochemical applications. GC×GC-TOFMS improves the resolution and separation efficiency of the compounds. It not only separates the compounds that coelute in conventional GC-MS (e.g., 4, 8-dimethyl-diamantane and trimethyl-diamantane) but also allows the identification of compounds that were not previously detected (e.g., trimethyl-diamantane (15A)). A reversed-phase column system improves the separation capabilities over the normal phase column system. The diamondoid indexes indicate that a representative condensate from Well DX 10 is highly mature with equivalent Ro being approximately 1.5%. PMID:23109861

Li, Shuifu; Hu, Shouzhi; Cao, Jian; Wu, Ming; Zhang, Dongmei

2012-01-01

331

Diamondoid Characterization in Condensate by Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometry: The Junggar Basin of Northwest China  

PubMed Central

Diamondoids in crude oil are useful for assessing the maturity of oil in high maturation. However, they are very difficult to separate and accurately quantify by conventional geochemical methods due to their low abundance in oil. In this paper, we use comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) to study the compounds in condensates from the Junggar Basin of northwest China and address their geological and geochemical applications. GC×GC-TOFMS improves the resolution and separation efficiency of the compounds. It not only separates the compounds that coelute in conventional GC-MS (e.g., 4, 8-dimethyl-diamantane and trimethyl-diamantane) but also allows the identification of compounds that were not previously detected (e.g., trimethyl-diamantane (15A)). A reversed-phase column system improves the separation capabilities over the normal phase column system. The diamondoid indexes indicate that a representative condensate from Well DX 10 is highly mature with equivalent Ro being approximately 1.5%.

Li, Shuifu; Hu, Shouzhi; Cao, Jian; Wu, Ming; Zhang, Dongmei

2012-01-01

332

Analysis of t-butylphenol acetylene condensed resin with methyl-methine linkages in vulcanized rubber by pyrolysis-gas chromatography/mass spectrometry  

PubMed

Methyl-methine linkages of Novolac, a commercially available t-butylphenol acetylene condensed (TBPA) resin, have been identified by recognition of pyrolysis pathways using pyrolysis-gas chromatography/mass spectrometry (Py-GC/mS) in vulcanized rubber. The diagnostic mass spectrum of t-butylphenol with methyl-methine linkages between phenolic rings was observed at m/z 192, corresponding to 4-t-butyl-2-ethyl-6-methylphenol. Other molecular ions were observed at m/z 178, 164, and 150 in the characteristic pyrolyzates. The ion at m/z 192 in the TBPA resin was observed to be characteristic for methyl-methine linkages between the phenolic groups, and the analytical pyrolysis-GC/mS method was thus able to identify the resin at low levels in vulcanized rubber. Copyright 1999 John Wiley & Sons, Ltd. PMID:10482900

Kim; Lee

1999-01-01

333

COMPARISON OF LEVELS OF SULFOLANE AND DIISOPROPANOLAMINE IN NATURAL WETLAND VEGETATION EXPOSED TO GAS-CONDENSATE CONTAMINATED GROUND WATER  

Microsoft Academic Search

Groundwater containing the process chemicals sulfolane (tetrahydrothiophene 1,1-dioxide) and diisopropanolamine (DIPA) has contaminated a wetland in the vicinity of a sour-gas natural gas processing facility. Of concern is the extent of which these contaminants are taken up by vegetation and the associated risk to wildlife that may eat the plants. All sampled wetland plants contained detectable levels of sulfolane and

John V. Headley; Leslie C. Dickson; Kerry M. Peru

2002-01-01

334

A new many-body theory for the superfluid Fermi gas in the molecular Bose-Einstein condensed state  

NASA Astrophysics Data System (ADS)

Recent experimental advances on ultracold atomic Fermi gases pose new challenges to condensed matter theory. It has been established that there is a continuous crossover from BCS to molecular Bose-Einstein condensation (BEC) as the attractive interaction is increased. The lowest order ground state wave function which describes this crossover was first introduced by D. M. Eagles and A. J. Leggett (EL). The present Thesis aims at formulating an improved many-body ground state wave function, which represents a modification of the Eagles-Leggett ground state to include 4-fermion, and all higher correlations. We show that this theory, importantly, contains the exactly determined 4-fermion scattering behavior at short distances and, meanwhile, reduces to composite-boson Bogoliubov physics at long distances, with the correct intermolecular interaction built in. Our approach can be viewed as a new diagrammatic methodology, based on a perturbation series in the many-body wave function as distinct from a perturbation series in the interparticle interactions. Some basic properties of this wave function are studied, and its parameters, as well as the system's equation of state, are computed beyond mean-field. Using the constraints imposed by collective mode and cloud size experiments near the unitary interaction regime, we determine the range of kFa where the new perturbation method is applicable, and the range where the positive frequency shifts in the breathing modes of a trapped atomic cloud, albeit small, may be observable. Here kF is the Fermi wave vector and a is the 2-fermion scattering length. Other observable implications of this theory are briefly discussed. We also discuss the possible implications of this theory in other physical systems, in particular high temperature superconductors.

Tan, Shina

335

Condensation polyimides  

NASA Technical Reports Server (NTRS)

Polyimides belong to a class of polymers known as polyheterocyclics. Unlike most other high temperature polymers, polyimides can be prepared from a variety of inexpensive monomers by several synthetic routes. The glass transition and crystalline melt temperature, thermooxidative stability, toughness, dielectric constant, coefficient of thermal expansion, chemical stability, mechanical performance, etc. of polyimides can be controlled within certain boundaries. This versatility has permitted the development of various forms of polyimides. These include adhesives, composite matrices, coatings, films, moldings, fibers, foams and membranes. Polyimides are synthesized through both condensation (step-polymerization) and addition (chain growth polymerization) routes. The precursor materials used in addition polyimides or imide oligomers are prepared by condensation method. High molecular weight polyimide made via polycondensation or step-growth polymerization is studied. The various synthetic routes to condensation polyimides, structure/property relationships of condensation polyimides and composite properties of condensation polyimides are all studied. The focus is on the synthesis and chemical structure/property relationships of polyimides with particular emphasis on materials for composite application.

Hergenrother, P. M.

1989-01-01

336

Mechanisms controlling the global oceanic distribution of the inert gases argon, nitrogen and neon  

Microsoft Academic Search

Dissolved inert gas measurements in the ocean yield important information about processes that occur during water mass formation. We present argon, nitrogen, and neon data from the subtropical and subpolar North Pacific and the subtropical North Atlantic. All three gases were supersaturated at the surface. In the deep ocean, Ar and N2 were undersaturated while Ne re- mained supersaturated. All

Roberta C. Hamme; Steven R. Emerson

2002-01-01

337

Microscopic Wave Function of Alpha Condensation  

NASA Astrophysics Data System (ADS)

We explain how to treat a microscopic wave function of ?-condensation named THSR taking 3?-condensation as a typical example. The microscopic model, which fully takes into account the Pauli principle between all the constituent nucleons and effective inter-nucleon forces simultaneously, can play an important role in reproducing an ?-gas-like nature thanks to ?-condensation. We study its typical features by giving numerical results of the norm kernel for 3?-condensation.

Tohsaki, Akihiro; Funaki, Yasuro; Horiuchi, Hisashi; Röpke, Gerd; Schuck, Peter; Yamada, Taiichi

338

Condensation Processes in Geothermal Systems  

NASA Astrophysics Data System (ADS)

We model condensation processes in geothermal systems to understand how this process changes fluid chemistry. We assume two processes operate in geothermal systems: 1) condensation of a vapor phase derived by boiling an aqueous geothermal fluid into a cool near surface water and 2) condensation of a magmatic vapor by a deep circulating meteoric thermal fluid. It is assumed that the condensation process has two stages. Initially the condensing fluid is under saturated in gaseous species. Condensation of the vapor phase continues until the pressure on the fluid equals the sum of the partial pressures of water and the dissolved gaseous species. At that time bubbles flux through the condensing fluid. In time the fluid and fluxing gas phase come to equilibrium. Calculation shows that during the second stage of the condensation process the liquid phase becomes enriched in more soluble gaseous species like CO2 and H2S, and depleted in less soluble species like CH4 and N2. Stage 2 condensation processes can therefore be monitored by ratios of more and less condensable species like CO2/N2. Condensation of vapor released by boiling geothermal fluids results in liquids with high concentrations of H2S and CO2 like is seen in geothermal system steam-heated waters. Condensation of a magmatic vapor into circulating meteoric water has been proposed, but not well demonstrated. We compare to our models the Cerro Prieto, Mexico gas analysis data set collected over twelve years time by USGS personnel. It was assumed for modeling that the Cerro Prieto geothermal fluids are circulating meteoritic fluids with N2/Ar ratios about 40 to which is added a magmatic vapor with N2/Ar ratio = 400. The Cerro Prieto analyses show a strong correlation between N2/Ar and CO2/N2 as predicted by calculation. Two dimensional image plots of well N2/Ar + CO2/N2 show a bull's-eye pattern on the geothermal field. Image plots of analyses collected over a year or less time show N2/Ar and CO2/N2 hot spots. Plotting data for individual wells show a hysteresis like loops on time vs. CO2/N2 diagrams. Our analysis demonstrates that condensation of magmatic vapor into convecting meteoric waters is a viable process. Condensation explains variations in Cerro Prieto geothermal system gas chemistry and is compatible with helium isotope data. Locally condensation appears to wax and wane over a time periods of about 10 years.

Norman, D. I.; Moore, J. N.

2005-12-01

339

46 CFR 154.1740 - Vinyl chloride: Inhibiting and inerting.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Vinyl chloride: Inhibiting and inerting. 154...Requirements Ā§ 154.1740 Vinyl chloride: Inhibiting and inerting. When a vessel is carrying vinyl chloride, the master shall ensure that:...

2013-10-01

340

Trilepton signals in the inert doublet model  

SciTech Connect

In this work, we investigate the prospects for detecting the Inert Doublet Model via the trilepton channel at the LHC. We present a set of representative benchmark scenarios in which all applicable constraints are satisfied, and show that in some of these scenarios, it is possible to obtain a signal at the 5{sigma} significance level or better with integrated luminosity of 300 fb{sup -1}.

Miao, Xinyu; Su, Shufang [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); Thomas, Brooks [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

2010-08-01

341

mJ Mixing in Oriented 42P12 Potassium Atoms, Induced by Collisions with Inert Gases  

Microsoft Academic Search

A modified Zeeman scanning method was used to excite selectively the magnetic substates of the 42P12 potassium atoms mixed with inert gases and placed in a strong magnetic field. The resulting potassium-inert-gas atomic collisions induced mJ mixing in potassium, which manifested itself by the depolarization of the potassium resonance fluorescence. The polarization measurements yielded the following disorientation cross sections: K-He:

W. Berdowski; L. Krause

1968-01-01

342

mJ Mixing in Oriented 42P32 Potassium Atoms Induced by Collisions with Inert Gases  

Microsoft Academic Search

The cross sections for the decay of circular and of linear polarization in oriented 42P32 potassium atoms, induced in collision with inert-gas atoms, were determined in a series of fluorescence experiments. A modified Zeeman scanning method was used to populate selectively the mJ sublevels of the 2P32 potassium atoms mixed with inert gases and placed in a strong magnetic field.

W. Berdowski; T. Shiner; L. Krause

1971-01-01

343

Prediction of the condensation behavior of natural gas: A comparative study of the Peng-Robinson and the simplified-perturbed-hard-chain theory equations of state  

SciTech Connect

For the prediction of the condensation behavior of natural gas, one has to select an equation of state (EoS) which will be accurate in the temperature and pressure range of interest (10 < P/bar < 70 bar and 250 < T/K < 310). Another requirement of the selected EoS is that is easily can be adapted to a characterization procedure for the heavy-end fraction. For that purpose, two equations were tested: the Peng-Robinson (PR), which is one of the most applied cubic EoS, and the simplified-perturbed-hard-chain theory (SPHCT) equation, which is one of the simplest EoS based on sound statistical mechanical principles. In the underlying study, their predictive capabilities for the prediction of saturated vapor pressures of pure compounds and vapor/liquid equilibrium pressures for binary mixtures are compared. Only components present in natural gas are considered. In addition, new pure-component parameters for the SPHCT EoS for n-alkanes are evaluated. Also a method to find the characteristic energy for non-n-alkane molecules is proposed in this study. This study revealed that the PR EoS predicts more accurately the liquid phase composition, whereas the SPHCT EoS is superior for the gas phase prediction, especially for asymmetric binary mixtures. It was concluded that, with respect to the purpose of this study, both EoS, when used with optimum binary interaction parameters, have an equivalent descriptive accuracy. Therefore, the simpler PR EoS was preferred to describe natural gas mixtures.

Voulgaris, M.E.; Peters, C.J.; Swaan Arons, J. de [Delft Univ. of Technology (Netherlands). Lab. of Applied Thermodynamics and Phase Equilibria] [Delft Univ. of Technology (Netherlands). Lab. of Applied Thermodynamics and Phase Equilibria

1998-05-01

344

Development of the Thermal Decomposition Mechanism of Polyether Polyurethane Foam Using Both Condensed and Gas-Phase Release Data  

Microsoft Academic Search

The thermal decomposition mechanism of solids is a main input data of codes in fire research. In this research, the evolution of thermal properties versus temperature is used together with the measurement of gas effluents to understand the decomposition of polyether polyurethane foam (PPUF). A wide characterization of the virgin fuel and the intermediary species that enter into the thermal

Thomas Rogaume; Lucas Bustamante Valencia; Eric Guillaume; Franck Richard; Jocelyn Luche; Guillermo Rein; Jose Luis Torero

2011-01-01

345

Fundamental insights on impact of non-condensible gas evolution from coating pyrolysis and intentional injection on molten-aluminum water explosion onset during direct-chill casting  

SciTech Connect

Explosive interactions between molten aluminum and water are being studied with a focus on fundamentals to determine what causes robust-enough triggers for explosion onset, to determine the extent of protection provided from various coatings and to develop a fundamentally-based simple, cost-effective novel methodology for prevention. The workscope includes experimentation and mathematical modeling of the interactions between molten metals and water at various different coated and uncoated surfaces. Phenomenological issues related to surface wettability, gas generation from coatings, charring of coatings, inertial constraint, melt temperature, water temperature, external shocks are being investigated systematically to gage their relative impact on the triggerability of surface-assisted steam explosions. The steam explosion triggering studies (SETS) facility was designed and constructed as a rapid-turnaround, cost-effective, and safe means to address these phenomenological issues. Data from SETS tests have indicated that, non-condensible gas (NCG) generation during paint pyrolysis plays a predominant role in explosion prevention. This paper describes results of studies on impact of deliberate NCG injection on explosion prevention, via molten melt drops free-falling into water, as well as from tests using the SETS facility for studying entrapment induced explosive boiling. SETS is also being used to obtain information on time-varying and integral amounts of NCGs generated from various paints. Relevant data are presented. Results of investigations, taken together provide compelling evidence on the positive role NCGs play on explosion prevention.

Taleyarkhan, R.P.; Kim, S.H. [Oak Ridge National Lab., TN (United States); Gulec, K. [Oak Ridge Associated Universities, TN (United States)

1998-05-01

346

Pressure Effect of Various Inert Gases on the Phase Behavior of Polystyrene-block-Poly(n-pentyl methacrylate) Copolymer  

NASA Astrophysics Data System (ADS)

We investigated the pressure effect of three inert gases (nitrogen, helium and argon) on the phase behavior of polystyrene-block-poly(n-pentylmethacrylate) copolymer (PS-b-PnPMA) showing closed-loop phase behavior and baroplasticity. Helium gas pressure enhanced the miscibility between PS and PnPMA blocks similar to the hydrostatic pressure. Very interestingly, however, with increasing nitrogen and argon gas pressure, the miscibility between the two blocks decreased even though these two are also considered as inert gases. To explain these unexpected results, we measured the amount of gas absorption into each block. The experimentally measured gas absorption results are consistent with the theoretical ones based on the Sanchez-Lacombe theory. The results in this study imply that well-known and widely employed inert gases such as nitrogen and argon could significantly affect the phase behavior of a weakly interacting block copolymer at high pressures.

Moon, Hong Chul; Kim, Hye Jeong; Cho, Junhan; Kim, Jin Kon

2013-03-01

347

Cement solidification of simulated off-gas condensates from vitrification of low-level nuclear waste solutions  

Microsoft Academic Search

Solidification in a cementitious matrix is a viable alternative for low-level nuclear waste management; it is therefore important to understand the behavior and properties of such wasteforms. We have examined the cementitious solidification of simulated off-gas waste streams resulting from the vitrification of low-level nuclear waste. Different possible methods for scrubbing the off-gasses from a vitrifier give rise to three

A Katz; A. R Brough; R. J Kirkpatrick; L. J Struble; G. K Sun; J. F Young

2001-01-01

348

Absorption removal of sulfur dioxide by falling water droplets in the presence of inert solid particles  

NASA Astrophysics Data System (ADS)

An experimental analysis of the absorption removal of sulfur dioxide by the free falling water droplets containing the inert solid particles is presented. The wheat flour powder is introduced as the inert solid particles. Tests with and without the flour powder in the water droplets are examined. The mass fluxes and mass transfer coefficients of SO 2 for the cases with and without the flour powder are compared to elucidate the effects of the inert solid particles contained in the water droplets on the gas absorption. The results indicate aignificant difference between the two cases for the concentrations of the flour powder in the absorbent droplets ( Cs) within the ranges of the experimental conditions, namely 0.1 to 10 wt% flour powder in the absorbent droplets. In general, the inert solid particles of the flour powder as the impurities in the water droplets tend to decrease the SO 2 absorption rate for the experimental absorption system under investigation. Various values of Cs cause various levels of the interfacial resistance and affect the gas absorption rate. The interfacial resistance is recognized by introducing an interfacial mass transfer coefficient ks with its reciprocal being proportional to the magnitude of the interfacial resistance. The values of 1/ ks may be computed by the use of the equation 1/ ks=(1/ KOLs-1/ KOL), where KOLs and KOL are the overall liquid-phase mass transfer coefficients with and without the inert solid particles, respectively. The values of ks with Cs of 0.1 to 10 wt% are about 0.295-0.032 cms -1 for absorbing 1000-3000 ppmv SO 2 with the water droplets. This kind of information is useful for the SO 2 removal and the information of acid rain that the impurities of the inert solid particles contaminate the water droplets.

Liu, I.-Hung; Chang, Ching-Yuan; Liu, Su-Chin; Chang, I.-Cheng; Shih, Shin-Min

349

The condensation with partial isolation model of condensation in the solar nebula  

Microsoft Academic Search

We have developed a nebular condensation model and a computational routine that potentially can account for the unequilibrated mineral assemblages in chondritic meteorites. The model assumes that as condensation proceeds a specified fraction (called the isolation degree, x) of the existing condensate is steadily withdrawn from reactive contact with the residual gas, presumably as a result of the growth and

Michail I. Petaev; John A. Wood

1998-01-01

350

Polariton condensates  

SciTech Connect

Most students of physics know about the special properties of Bose-Einstein condensates (BECs) as demonstrated in the two best-known examples: superfluid helium-4, first reported in 1938, and condensates of trapped atomic gases, first observed in 1995. (See the article by Wolfgang Ketterle in PHYSICS TODAY, December 1999, page 30.) Many also know that superfluid {sup 3}He and superconducting metals contain BECs of fermion pairs. An underlying principle of all those condensed-matter systems, known as quantum fluids, is that an even number of fermions with half-integer spin can be combined to make a composite boson with integer spin. Such composite bosons, like all bosons, have the property that below some critical temperature--roughly the temperature at which the thermal de Broglie wavelength becomes comparable to the distance between the bosons--the total free energy is minimized by having a macroscopic number of bosons enter a single quantum state and form a macroscopic, coherent matter wave. Remarkably, the effect of interparticle repulsion is to lead to quantum mechanical exchange interactions that make that state robust, since the exchange interactions add coherently.

Snoke, David; Littlewood, Peter [University of Pittsburgh, Pennsylvania (United States); University of Cambridge (United Kingdom)

2010-08-15

351

Inhibition of hydrogen sulfide, methane, and total gas production and sulfate-reducing bacteria in in vitro swine manure by tannins, with focus on condensed quebracho tannins.  

PubMed

Management practices from large-scale swine production facilities have resulted in the increased collection and storage of manure for off-season fertilization use. Odor and emissions produced during storage have increased the tension among rural neighbors and among urban and rural residents. Production of these compounds from stored manure is the result of microbial activity of the anaerobic bacteria populations during storage. In the current study, the inhibitory effects of condensed quebracho tannins on in vitro swine manure for reduction of microbial activity and reduced production of gaseous emissions, including the toxic odorant hydrogen sulfide produced by sulfate-reducing bacteria (SRB), was examined. Swine manure was collected from a local swine facility, diluted in anaerobic buffer, and mixed with 1 %?w/v fresh feces. This slurry was combined with quebracho tannins, and total gas and hydrogen sulfide production was monitored over time. Aliquots were removed periodically for isolation of DNA to measure the SRB populations using quantitative PCR. Addition of tannins reduced overall gas, hydrogen sulfide, and methane production by greater than 90 % after 7 days of treatment and continued to at least 28 days. SRB population was also significantly decreased by tannin addition. qRT-PCR of 16S rDNA bacteria genes showed that the total bacterial population was also decreased in these incubations. These results indicate that the tannins elicited a collective effect on the bacterial population and also suggest a reduction in the population of methanogenic microorganisms as demonstrated by reduced methane production in these experiments. Such a generalized effect could be extrapolated to a reduction in other odor-associated emissions during manure storage. PMID:23149758

Whitehead, Terence R; Spence, Cheryl; Cotta, Michael A

2013-09-01

352

Gerdien Condenser System for Measuring Stratospheric Charged Particle Densities.  

National Technical Information Service (NTIS)

A Gerdien condenser system for measuring stratospheric charged particles densities is described. The system makes use of commercially available blowers to obtain the bulk gas flow through the condenser and a time of charge method for measuring collected c...

C. Sherman A. D. Bailey J. Borghetti

1984-01-01

353

Inert anodes and advanced smelting of aluminum  

SciTech Connect

This report provides a broad assessment of open literature and patents that exist in the area of inert anodes and their related cathode systems and cell designs, technologies that are relevant for the advanced smelting of aluminum. The report also discusses the opportunities, barriers, and issued associated with these technologies from a technical, environmental, and economic viewpoint. It discusses the outlook for the direct retrofit of advanced reduction technologies to existing aluminum smelters, and compares retrofits to ''brown field'' usage and ''green field'' adoption of the technologies. A number of observations and recommendations are offered for consideration concerning further research and development efforts that may be directed toward these advanced technologies. The opportunities are discussed in the context of incremental progress that is being made in conventional Hall-Heroult cell systems.

ASME Technical Working Group on Inert Anode Technologies

1999-07-01

354

Mucosal vaccination against tuberculosis using inert bioparticles.  

PubMed

Needle-free, mucosal immunization is a highly desirable strategy for vaccination against many pathogens, especially those entering through the respiratory mucosa, such as Mycobacterium tuberculosis. Unfortunately, mucosal vaccination against tuberculosis (TB) is impeded by a lack of suitable adjuvants and/or delivery platforms that could induce a protective immune response in humans. Here, we report on a novel biotechnological approach for mucosal vaccination against TB that overcomes some of the current limitations. This is achieved by coating protective TB antigens onto the surface of inert bacterial spores, which are then delivered to the respiratory tract. Our data showed that mice immunized nasally with coated spores developed humoral and cellular immune responses and multifunctional T cells and, most importantly, presented significantly reduced bacterial loads in their lungs and spleens following pathogenic challenge. We conclude that this new vaccine delivery platform merits further development as a mucosal vaccine for TB and possibly also other respiratory pathogens. PMID:23959722

Reljic, Rajko; Sibley, Laura; Huang, Jen-Min; Pepponi, Ilaria; Hoppe, Andreas; Hong, Huynh A; Cutting, Simon M

2013-11-01

355

Mucosal Vaccination against Tuberculosis Using Inert Bioparticles  

PubMed Central

Needle-free, mucosal immunization is a highly desirable strategy for vaccination against many pathogens, especially those entering through the respiratory mucosa, such as Mycobacterium tuberculosis. Unfortunately, mucosal vaccination against tuberculosis (TB) is impeded by a lack of suitable adjuvants and/or delivery platforms that could induce a protective immune response in humans. Here, we report on a novel biotechnological approach for mucosal vaccination against TB that overcomes some of the current limitations. This is achieved by coating protective TB antigens onto the surface of inert bacterial spores, which are then delivered to the respiratory tract. Our data showed that mice immunized nasally with coated spores developed humoral and cellular immune responses and multifunctional T cells and, most importantly, presented significantly reduced bacterial loads in their lungs and spleens following pathogenic challenge. We conclude that this new vaccine delivery platform merits further development as a mucosal vaccine for TB and possibly also other respiratory pathogens.

Reljic, Rajko; Sibley, Laura; Huang, Jen-Min; Pepponi, Ilaria; Hoppe, Andreas; Hong, Huynh A.

2013-01-01

356

Dielectric properties of a disordered Bose condensate  

Microsoft Academic Search

The frequency-dependent and wave-number-dependent dielectric properties of a condensate of a boson gas with static disorder are evaluated. For weak disorder the condensate is superfluid and the disorder induces a mass enchancement. For strong disorder the condensate is insulating and the static dielectric function is finite. Numerical solutions for the frequency dependence of the density relaxation function and the dynamical

A. Gold

1986-01-01

357

Understanding Condensation  

NSDL National Science Digital Library

Monica Hartman, Assistant Director for Science in St. Clair County, Michigan, conducted this research while she was the learning specialist in a small suburban district just outside a large Midwestern city. While teaching full time in this district she was also completing her doctoral program in education at the University of Michigan. In this chapter, she tells the story of a "science talk" about condensation among fifth graders. She acted as a source and facilitator of change as she and the fifth-grade teacher worked collaboratively to help students share responsibility for their own learning. She describes their continual assessment of student understanding that occurred as their students struggled to explain observations and as they, the teachers, carefully resisted the temptation to end the struggle by saying "that's right!"

Hartman, Monica

2007-12-01

358

The performance of two purification media in their removal of impurities from inert gases  

Microsoft Academic Search

Ultra-high-purity (UHP) inert gases such as N2 and Ar are utilized in the semiconductor industry as purge and carrier gases for IC manufacturing processes. High quality product production is extremely dependent on process gas purity at the point-of-use (POU). Removal of impurities such as moisture, O2, CO2, and CO is highly critical at the POU due to the detrimental effects

Jian Wei; Dmitry Kondrashov; Kareem Vakhshoori; Armando Colorado

1999-01-01

359

An approach to heat and mass transfer analysis during film condensation inside a vertical tube  

SciTech Connect

An Investigation was conducted to determine the effects of non-condensing gas on vapor condensation. Experiments were carried out during condensation of a mixture of water vapor/non-condensing gas along the inner surface of a vertical tube. Air was used as non-condensing gas and the various profiles of the water vapor/non-condensing gas mixture were employed. A theoretical analysis to predict the heat and mass transfer is presented. The amount of the condensed water obtained by the experiments was found to be close to the theoretical results. The obtained heat and mass transfer results were in good agreement with earlier published results.

Kotcioglu, I.; Gullapoglu, S. (Ataturk Univ., Erzurum (Turkey)); Uyarel, A.Y. (Gazi Univ., Ankara (Turkey)); Kaygusuz, K. (Karadeniz Technical Univ., Trabzon (Turkey)); Dincer, I. (TUBITAK-Marmara Research Center, Kocaeli (Turkey))

1993-03-01

360

Condensing furnaces: Lessons from a utility  

Microsoft Academic Search

for the last several years about 90% of the new natural gas furnaces installed in Wisconsin have been condensing furnaces and a number of lessons have been learned. If you avoid the common mistakes, condensing furnaces typically can deliver heating savings of 20-35 % assuming the old furnace was in the 60% AFUE range. This article describes the common mistakes

Beers

1994-01-01

361

Electrolytic production of high purity aluminum using ceramic inert anodes  

DOEpatents

A method of producing commercial purity aluminum in an electrolytic reduction cell comprising ceramic inert anodes is disclosed. The method produces aluminum having acceptable levels of Fe, Cu and Ni impurities. The ceramic inert anodes used in the process may comprise oxides containing Fe and Ni, as well as other oxides, metals and/or dopants.

Ray, Siba P. (Murrysville, PA); Liu, Xinghua (Monroeville, PA); Weirauch, Douglas A. (Murrysville, PA); DiMilia, Robert A. (Baton Rouge, LA); Dynys, Joseph M. (New Kensington, PA); Phelps, Frankie E. (Apollo, PA); LaCamera, Alfred F. (Trafford, PA)

2002-01-01

362

Electrolytic production of high purity aluminum using inert anodes  

DOEpatents

A method of producing commercial purity aluminum in an electrolytic reduction cell comprising inert anodes is disclosed. The method produces aluminum having acceptable levels of Fe, Cu and Ni impurities. The inert anodes used in the process preferably comprise a cermet material comprising ceramic oxide phase portions and metal phase portions.

Ray, Siba P. (Murrysville, PA); Liu, Xinghua (Monroeville, PA); Weirauch, Jr., Douglas A. (Murrysville, PA)

2001-01-01

363

Drying of Slurries in Fluidized Bed of Inert Particles  

Microsoft Academic Search

A fluid bed dryer with inert particles was used for drying of slurries. Experiments were performed in a cylindrical column 215 mm in diameter and 1200 mm in height with glass spheres as inert particles. Slurries of Zineb fungicide, copper hydroxide, calcium carbonate, and pure water were used as the feed material. The effects of operating conditions on dryer throughput and product

Zeljko B. Grbavcic; Zorana Lj Arsenijevic; Radmila V. Garic-Grulovic

2004-01-01

364

SWELLING AND INERT GAS DIFFUSION IN IRRADIATED URANIUM  

Microsoft Academic Search

The increases in volume which occur when uranium is irradiated are of ; considerable importance in nuclear engineering since they impose a ceiling to ; irradiation levels and efficiency. These limitations may be overcome to some ; extent by principles of design or by the development of improved materials based ; on an understanding of the fundamental processes involved in

R. S. Barnes; A. T. Churchman; A. J. E. Foreman; O. S. Plail; S. F. Pugh; G. N. Walton; G. C. Curtis; V. W. Eldred; J. A. Enderby; L. M. Wyatt

1959-01-01

365

Inert Welding/Brazing Gas Filters and Dryers  

NASA Technical Reports Server (NTRS)

The use of hybridized carbon/silicon carbide (C/SiC) fabric to reinforce ceramic matrix composite face sheets and the integration of such face sheets with a foam core creates a sandwich structure capable of withstanding high-heat-flux environments (150 W/sq cm) in which the core provides a temperature drop of 1,000 C between the surface and the back face without cracking or delamination of the structure. The composite face sheet exhibits a bilinear response, which results from the SiC matrix not being cracked on fabrication. In addition, the structure exhibits damage tolerance under impact with projectiles, showing no penetration to the back face sheet. These attributes make the composite ideal for leading-edge structures and control surfaces in aerospace vehicles, as well as for acreage thermal protection systems and in high-temperature, lightweight stiffened structures. By tailoring the coefficient of thermal expansion (CTE) of a carbon fiber containing ceramic matrix composite (CMC) face sheet to match that of a ceramic foam core, the face sheet and the core can be integrally fabricated without any delamination. Carbon and SiC are woven together in the reinforcing fabric. Integral densification of the CMC and the foam core is accomplished with chemical vapor deposition, eliminating the need for bond-line adhesive. This means there is no need to separately fabricate the core and the face sheet, or to bond the two elements together, risking edge delamination during use. Fibers of two or more types are woven together on a loom. The carbon and ceramic fibers are pulled into the same "pick" location during the weaving process. Tow spacing may be varied to accommodate the increased volume of the combined fiber tows while maintaining a target fiber volume fraction in the composite. Foam pore size, strut thickness, and ratio of face sheet to core thickness can be used to tailor thermal and mechanical properties. The anticipated CTE for the hybridized composite is managed by the choice of constituents, varying fiber tow sizes and constituent part ratios. This structural concept provides high strength and stiffness at low density 1.06 g/cu cm in panels tested. Varieties of face sheet constructions are possible, including variations in fiber type and weave geometry. The integrated structures possible with this composite could eliminate the need for non-load-bearing thermal protection systems on top of a structural component. The back sheet can readily be integrated to substructures through the incorporation of ribs. This would eliminate weight and cost for aerospace missions.

Goudy, Jerry

2009-01-01

366

Role of Carbon Dioxide in Inert Gas Narcosis.  

National Technical Information Service (NTIS)

The role of carbon dioxide and oxygen in high pressure narcosis was studied by exposing animals to hyperbaric conditions while maintaining them normoxic and normocapnic. Chickens were the experimental animal used. The unanaesthetized restrained birds were...

H. S. Weiss L. W. Torley

1975-01-01

367

Durable cathodes for high-power inert-gas arcs  

NASA Technical Reports Server (NTRS)

Cathode design minimizes evaporation of electrode material which may deposit on associated optical surfaces. It also results in stable operation and precise positioning of arc relative to optical collector. Innovation applies to high power light sources and to arcs used in industrial furnaces.

Decker, A. J.; Gettleman, C. C.; Goldman, G. C.; Hall, J. H.; Pollack, J. L.

1971-01-01

368

Fractionation in the solar nebula - Condensation of yttrium and the rare earth elements  

Microsoft Academic Search

The condensation of Y and the rare earth elements (REE) from the solar nebula may be controlled by thermodynamic equilibrium between gas and condensed solids. Highly fractionated REE patterns may result if condensates are removed from the gas before condensation is complete. It is found that the fractionation is not a smooth function of REE ionic radius but varies in

W. V. Boynton

1975-01-01

369

Temperature and gas-phase composition measurements in supersonic flows using tunable diode laser absorption spectroscopy: The effect of condensation on the boundary-layer thickness  

NASA Astrophysics Data System (ADS)

We used a tunable diode laser absorption spectrometer and a static-pressure probe to follow changes in temperature, vapor-phase concentration of D2O, and static pressure during condensation in a supersonic nozzle. Using the measured static-pressure ratio p/p0 and the mass fraction of the condensate g as inputs to the diabatic flow equations, we determined the area ratio (A/A*)Wet and the corresponding centerline temperature of the flow during condensation. From (A/A*)Wet we determined the boundary-layer displacement thickness during condensation (?#)Wet. We found that (?#)Wet first increases relative to the value of ?# in a dry expansion (?#)Dry before becoming distinctly smaller than (?#)Dry downstream of the condensation region. After correcting the temperature gradient across the boundary layers, the temperature determined from p/p0 and g agreed with the temperature determined by the laser-absorption measurements within our experimental error (+/-2 K), except when condensation occurred too close to the throat. The agreement between the two temperature measurements let us draw the following two conclusions. First, the differences in the temperature and mole fraction of D2O determined by the two experimental techniques, first observed in our previous study [P. Paci, Y. Zvinevich, S. Tanimura, B. E. Wyslouzil, M. Zahniser, J. Shorter, D. Nelson, and B. McManus, J. Chem. Phys. 121, 9964 (2004)], can be explained sufficiently by changes in ?# caused by the condensation of D2O, except when the phase transition occurs too close to the throat. Second, the extrapolation of the equation, which expresses the temperature dependence of the heat of vaporization of bulk D2O liquid, is a good estimate of the heat of condensation of supercooled D2O down to 210 K.

Tanimura, Shinobu; Zvinevich, Yury; Wyslouzil, Barbara E.; Zahniser, Mark; Shorter, Joanne; Nelson, David; McManus, Barry

2005-05-01

370

Temperature and gas-phase composition measurements in supersonic flows using tunable diode laser absorption spectroscopy: The effect of condensation on the boundary-layer thickness  

Microsoft Academic Search

We used a tunable diode laser absorption spectrometer and a static-pressure probe to follow changes in temperature, vapor-phase concentration of D2O, and static pressure during condensation in a supersonic nozzle. Using the measured static-pressure ratio p\\/p0 and the mass fraction of the condensate g as inputs to the diabatic flow equations, we determined the area ratio (A\\/A*)Wet and the corresponding

Shinobu Tanimura; Yury Zvinevich; Barbara E. Wyslouzil; Mark Zahniser; Joanne Shorter; David Nelson; Barry McManus

2005-01-01

371

Inert Higgs doublet extension of the NMSSM  

NASA Astrophysics Data System (ADS)

We introduce one pair of inert Higgs doublets {Hd,Hu} and singlets {Nc,N}, and consider their couplings with the Higgs doublets of the minimal supersymmetric standard model (MSSM), W ?yNNchuHd+yN'NhdHu. We assign extra U(1)Z' gauge charges only to the extra vectorlike superfields, and so all the MSSM superfields remain neutral under the new U(1)Z'. They can be an extension of the "? term," W ??Shuhd in the next-to MSSM (NMSSM). Because of the U(1)Z', the maximally allowed low energy value of yN can be lifted up to 0.85, avoiding a Landau pole (LP) below the grand unification scale. Such colorless vectorlike superfields remarkably enhance the radiative MSSM Higgs mass particularly for large tan? through the yN term and the corresponding holomorphic soft term. As a result, the lower bound of ? and the upper bound of tan? can be relaxed to disappear from the restricted parameter space of the original NMSSM, 0.6?? ?0.7 and 1m˜t?700 GeV. Thus, the valid parameter space significantly expands up to 0?? ?0.75, 0?yN?0.88, and 2?tan??50, evading the LP problem and also explaining the 126 GeV Higgs mass naturally.

Kyae, Bumseok

2014-04-01

372

Neutrinos from Inert Doublet dark matter  

SciTech Connect

We investigate the signatures of neutrinos produced in the annihilation of WIMP dark matter in the Earth, the Sun and at the Galactic centre within the framework of the Inert Doublet Model and extensions. We consider a dark matter candidate, that we take to be one of the neutral components of an extra Higgs doublet, in three distinct mass ranges, which have all been shown previously to be consistent with both WMAP abundance and direct detection experiments exclusion limits. Specifically, we consider a light WIMP with mass between 4 and 8 GeV (low), a WIMP with mass around 60-70 GeV (middle) and a heavy WIMP with mass above 500 GeV (high). In the first case, we show that capture in the Sun may be constrained using Super-Kamiokande data. In the last two cases, we argue that indirect detection through neutrinos is challenging but not altogether excluded. For middle masses, we try to make the most benefit of the proximity of the so-called 'iron resonance' that might enhance the capture of the dark matter candidate by the Earth. The signal from the Earth is further enhanced if light right-handed Majorana neutrinos are introduced, in which case the scalar dark matter candidate may annihilate into pairs of mono-energetic neutrinos. In the case of high masses, detection of neutrinos from the Galactic centre might be possible, provided the dark matter abundance is substantially boosted.

Andreas, Sarah; Tytgat, Michel H.G.; Swillens, Quentin, E-mail: Sarah.Andreas@rwth-aachen.de, E-mail: mtytgat@ulb.ac.be, E-mail: qswillen@ulb.ac.be [Service de Physique Theorique, Universite Libre de Bruxelles, CP225, Bld du Triomphe, B-1050 Brussels (Belgium)] [Service de Physique Theorique, Universite Libre de Bruxelles, CP225, Bld du Triomphe, B-1050 Brussels (Belgium)

2009-04-15

373

Formation Dynamics of a Fermion Pair Condensate  

NASA Astrophysics Data System (ADS)

The dynamics of pair condensate formation in a strongly interacting Fermi gas close to a Feshbach resonance was studied. We employed a phase-shift method in which the delayed response of the many-body system to a modulation of the interaction strength was recorded. The observable was the fraction of condensed molecules in the cloud after a rapid magnetic field ramp across the Feshbach resonance. The measured response time was slow compared to the rapid ramp, which provides final proof that the molecular condensates reflect the presence of fermion pair condensates before the ramp.

Zwierlein, M. W.; Schunck, C. H.; Stan, C. A.; Raupach, S. M.; Ketterle, W.

2005-05-01

374

An analysis of the effect of inert gases on ozone generation using dielectric barrier discharge in oxygen  

NASA Astrophysics Data System (ADS)

This paper studies the influence of inert gases He, Ar, Kr and Xe on ozone generation in a dielectric barrier reactor fed by oxygen feed gas. Results show that inert gas additions would lead to lower applied voltage, discharge power and reduced field. The electron energy distribution function shifts to the right though inert gas addition would lead to a lower reduced field with He, Ar and Kr addition, but it shifts to the left with Xe addition. The effective electron density decreases with inert gas content. With respect to Ar/O2, Kr/O2 and Xe/O2 mixture, conversion ratio of oxygen into ozone and ozone yield would increase with increasing Ar, Kr or Xe content, the growth rates follow the order of Xe > Kr > Ar. Such behaviors can be ascribed to the fact that Ar*, Kr* and Xe* could provide another effective pathway to produce oxygen atom through penning dissociation of O2 and metastable species due to their relatively low excitation threshold and considerable rate coefficients.

Wei, Linsheng; Yuan, Dingkun; Zhang, Yafang; Hu, Zhaoji; Tan, Zhihong; Dong, Guopan; Tao, Siqi

2014-01-01

375

Simple Techniques For Assessing Impacts Of Oil And Gas Operations On Public Lands: A Field Evaluation Of A Photoionization Detector (PID) At A Condensate Release Site, Padre Island National Seashore, Texas  

USGS Publications Warehouse

Simple, cost-effective techniques are needed for land managers to assess the environmental impacts of oil and gas production activities on public lands, so that sites may be prioritized for remediation or for further, more formal assessment. Field-portable instruments provide real-time data and allow the field investigator to extend an assessment beyond simply locating and mapping obvious disturbances. Field investigators can examine sites for the presence of hydrocarbons in the subsurface using a soil auger and a photoionization detector (PID). The PID measures volatile organic compounds (VOC) in soil gases. This allows detection of hydrocarbons in the shallow subsurface near areas of obvious oil-stained soils, oil in pits, or dead vegetation. Remnants of a condensate release occur in sandy soils at a production site on the Padre Island National Seashore in south Texas. Dead vegetation had been observed by National Park Service personnel in the release area several years prior to our visit. The site is located several miles south of the Malaquite Beach Campground. In early 2001, we sampled soil gases for VOCs in the area believed to have received the condensate. Our purpose in this investigation was: 1) to establish what sampling techniques might be effective in sandy soils with a shallow water and contrast them with techniques used in an earlier study; and 2) delineate the probable area of condensate release. Our field results show that sealing the auger hole with a clear, rigid plastic tube capped at the top end and sampling the soil gas through a small hole in the cap increases the soil VOC gas signature, compared to sampling soil gases in the bottom of an open hole. This sealed-tube sampling method increases the contrast between the VOC levels within a contaminated area and adjacent background areas. The tube allows the PID air pump to draw soil gas from the volume of soil surrounding the open hole below the tube in a zone less influenced by atmospheric air. In an open hole, the VOC readings seem to be strongly dependent on the degree of diffusion and advection of soil gas VOCs into the open hole from the surrounding soil, a process that may vary with soil and wind conditions. Making measurements with the sealed hole does take some additional time (4-7 minutes after the hole is augered) compared to the open-hole technique (1-2 minutes). We used the rigid-plastic tube technique to survey for soil gas VOCs across the entire site, less than ? acre. Condensate has impacted at least 0.28 acres. The impacted area may extend northwest of the surveyed area.

Otton, James K.; Zielinski, Robert A.

2001-01-01

376

Conversion of methane to hydrogen in a reversible flow superadiabatic inert porous medium reactor  

NASA Astrophysics Data System (ADS)

Using the analysis of the experimental data on partial oxidation of methane as an example, we have shown that the chemical processes in the inert medium of a reciprocating flow reactor can be modeled with good accuracy by the standard kinetic scheme for homogeneous processes due to the fact that the gas flow in the region of combustion is described by two temperatures — the gas and framework temperatures. Such a modification of the chemical model requires neither changing the recognized mechanism of homogeneous chemistry nor correcting the volume heat transfer coefficient.

Alabbadi, N. M.; Al-Musa, A. S.; Dmitrenko, Yu. M.; Martynenko, V. V.; Shabunya, S. I.; Al-Maiman, S. I.; Al-Enazi, K. B.; Al-Zhuhani, M. S.

2011-11-01

377

Growth and development in inert non-aqueous liquids. [of higher plants  

NASA Technical Reports Server (NTRS)

A preview is presented of the survival and growth capabilities of higher plants in non-aqueous, inert liquids. The two media which were used are mineral (white) oil and fluorochemical inert liquid FC-75. Both liquids dissolve oxygen and carbon dioxide readily, but are insoluble in water. Consequently, plants submerged in these liquids are capable of gas exchange with the atmosphere, but possess a water impermeable coating the dimensions of which are determined by the size of the liquid holding container. In a sense, growing plants in a tank of mineral oil imparts on them a cuticle. Plants plus prescribed volumes of water were innoculated into mineral oil. Organisms with minimal water supplied could then be observed. Also, submersed plants covered with an oil slick were shown to be capable of growth in dessicating atmospheres.

Siegel, S. M.

1974-01-01

378

Results from electrolysis test of a prototype inert anode: Inert Electrode Program  

SciTech Connect

Nonconsumable or inert anodes are being developed at the Pacific Northwest Laboratory (PNL)({sup a}) for use in the electrolytic production of aluminum. A series of laboratory test on the laboratory scale (Hart et al. 1987; Strachan et al. 1989; Marschman 1989) has shown the technology to be potentially feasible. A series of larger-scale experiments are now being run to determine the viability of the technology on a commercial scale. The results reported here are from a test performed at the Reynolds Metals Company, Manufacturing Technology Laboratory, Sheffield, Alabama, using a prototype anode. The prototype anode was approximately 15 cm in diameter and 20 cm high (Figure 1.1). The objectives of the test were to determine if an anode, produced by a commercial vendor, could survive in a test under conditions approximating those found in a commercial electrolysis cell; to familiarize the Reynolds staff with the operation of such an anode in a subsequent pilot cell test of the inert anode technology; and to familiarize the PNL staff with the operations at the Reynolds Metals Company facility. 8 refs., 39 figs., 9 tabs.

Strachan, D.M.; Windisch, C.F. Jr.; Koski, O.H.; Morgan, L.G. (Pacific Northwest Lab., Richland, WA (USA)); Peterson, R.D.; Richards, N.E.; Tabereaux, A.T. (Reynolds Metals Co., Sheffield, AL (USA). Mfg. Technology Lab.)

1990-05-01

379

40 CFR 174.705 - Inert ingredients from sexually compatible plant.  

Code of Federal Regulations, 2013 CFR

...Inert ingredients from sexually compatible plant. 174.705 Section 174.705 Protection...PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS List of Approved...Inert ingredients from sexually compatible plant. An inert ingredient, and...

2013-07-01

380

Technical basis for storage of Zircaloy-clad spent fuel in inert gases  

SciTech Connect

This report summarizes the technical bases to establish safe conditions for dry storage of Zircaloy-clad fuel. Dry storage of fuel with zirconium alloy cladding has been licensed in Canada, the Federal Republic of Germany, and Switzerland. In addition, dry storage demonstrations, hot cell tests, and modeling have been conducted using Zircaloy-clad fuel. The demonstrations have included irradiated boiling water reactor, pressurized heavy-water reactor, and pressurized water reactor (PWR) fuel assemblies. Irradiated fuel has been emplaced in and retrieved from metal casks, dry wells, silos, and a vault. Dry storage tests and demonstrations have involved {similar_to}5,000 fuel rods, and {similar_to}600 rods have been monitored during dry storage in inert gases with maximum cladding temperatures ranging from 50 to 570{sup 0}C. Although some tests and demonstrations are still in progress, there is currently no evidence that any rods exposed to inert gases have failed (one PWR rod exposed to an air cover gas failed at {similar_to}70{sup 0}C). Based on this favorable experience, it is concluded that there is sufficient information on fuel rod behavior, storage conditions, and potential cladding failure mechanisms to support licensing of dry storage in the United States. This licensing position includes a requirement for inert cover gases and a maximum cladding temperature guideline of 380{sup 0}C for Zircaloy-clad fuel. Using an inert cover gas assures that even if fuel with cladding defects were placed in dry storage, or if defects develop during storage, the defects would not propagate. Tests and demonstrations involving Zircaloy-clad rods and assemblies with maximum cladding temperatures above 400{sup 0}C are in progress. When the results from these tests have been evaluated, the viability of higher temperature limits should be examined. Acceptable conditions for storage in air and dry storage of consolidated fuel are issues yet to be resolved.

Johnson, A.B. Jr.; Gilbert, E.R.

1983-09-01

381

Operator's Manual for Computerized Gas Metering System (Flammable Gas).  

National Technical Information Service (NTIS)

The computerized metering system for flammable gas prevents an explosive mixture from occurring when testing a vessel. Because the original metering system for inert gas lacked this safety precaution, additional hardware and software features were made to...

D. Bell K. Blaedel M. Brooks J. Cervelli G. Koide

1984-01-01

382

Condensation inside tubes: Condensate film coefficient for vertical downflow  

NASA Astrophysics Data System (ADS)

ESDU 91024 presents a procedure for calculating the local (point) condensate film heat transfer coefficient at a prescribed vapor mass flux and the mean coefficient for the case when the saturation temperature is approximately constant over the entire condensing length. It applies to flow regimes in which the flow is controlled by vapor shear at the film interface or by gravity with either a wavy laminar flow or a turbulent film. Critria to establish the transition from mist-annular to annular flow and from annular to slug flow are included. The procedure applies to co-current downward flow; for reflux condensation ESDU 89038 should be consulted. The method depends on a correlation for the local coefficient extracted from the literature that was tested against experimental data also taken from the literature. No significant trends were seen with condensate or vapor phase Reynolds number, interfacial shear stress, vapor mass fraction, or flow regime parameter (a parameter giving a non-dimensional gas phase velocity). Typical correlation plots illustrate that behavior and show that the data correlate within 30 percent. The treatment of vapor desuperheating is considered, and the effect of condensate sub-cooling is treated. Step-by-step calculation procedures are presented and their use illustrated by a worked example.

1991-11-01

383

Numerical Analysis of Solitary Wave Influence on the Film-wise Condensation in Presence of Non-Condensable Gases  

Microsoft Academic Search

This paper is dealing with the analysis of condensation in presence of non-condensable gas on a laminar liquid film falling down on a vertical smooth surface. Particular interest is focused on the influence of solitary waves on the condensation process. Solutions to the pressure, velocity, temperature and additional scalar variable fields are obtained numerically by solving two -- dimensional Navier

Krzysztof Karkoszka; Henryk Anglart

2006-01-01

384

Inertance Tube Modeling and the Effects of Temperature  

NASA Astrophysics Data System (ADS)

Pulse tube refrigerators (PTRs) have made dramatic improvements in reliability, efficiency and usage. Inertance tube PTRs have been one of the keys to these improvements. The inertance tube is the component in the PTR that most easily affects the control of the PTR fluid dynamics. In one application in multistage cryocoolers, the performance of inertance tubes at the cryogenic temperatures is of interest. One purpose of this paper is to understand how temperature and the size of the reservoir influence the phase shift between mass flow rate and pressure at the inlet of the inertance tube. Various models including a two dimensional Computational Fluid Dynamics (CFD) will be compared to understand how these models can predict the phase shift and the acoustic power.

Dodson, C.; Razani, A.; Roberts, T.

2010-04-01

385

Inert electrodes program: Fiscal Year 1987 Annual Report  

SciTech Connect

The Inert Electrodes Program is being conducted at the Pacific Northwest Laboratory (PNL) for the US Department of Energy (DOE), Office of Industrial Programs (OIP). The purpose of the program is to develop long-lasting, energy-efficient anodes, cathodes, and ancillary equipment for Hall-Heroult cells used by aluminum industry. The program is divided into three tasks with the following objectives: Inert Anode Development - to improve the energy efficiency of Hall-Heroult cells by development of inert anodes; Stable Cathode Studies - to develop methods for retrofitting Hall-Heroult cells with TiB/sub 2/-based cathode materials; and Sensor Development - to devise sensors to control the chemistry of Hall-Heroult Cells using stable anodes and cathodes. This Inert Electrodes Program annual report highlights the major technical accomplishment of FY 1987. The accomplishments are presented in the following sections: Management, Materials Development and Testing, Materials Evaluation, Stable Cathode Studies, and Sensor Development. 50 refs., 47 figs.

Koski, O.H.; Marschman, S.C.; Schilling, C.H.; Windisch, C.F.

1988-12-01

386

114. SMALL ARMS (BUILDINGS 9798) AND INERT STOREHOUSE (BLDGS. 1031040) ...  

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

114. SMALL ARMS (BUILDINGS 97-98) AND INERT STOREHOUSE (BLDGS. 103-1040) PLAN AND ELEVATIONS, FULLER/SCOTT, MARCH 15, 1941. QP ACC 1791. - Quonset Point Naval Air Station, Roger Williams Way, North Kingstown, Washington County, RI

387

Cermet sphere-pac concept for inert matrix fuel  

Microsoft Academic Search

In the inert matrix fuel concept, plutonium reprocessed from spent fuel is burned in an inert matrix, e.g. yttria-stabilized zirconia. Coming from wet reprocessing, the internal gelation can perform an easy micro-spheres production. Utilization of these particles in a sphere-pac realizes a direct fuel production. Besides being economical, this direct usage offers an almost dustless fabrication. One disadvantage of yttria-stabilized

M. A. Pouchon; M. Nakamura; Ch. Hellwig; F. Ingold; C. Degueldre

2003-01-01

388

Optimizing process vacuum condensers  

SciTech Connect

Vacuum condensers play a critical role in supporting vacuum processing operations. Although they may appear similar to atmospheric units, vacuum condensers have their own special designs, considerations and installation needs. By adding vacuum condensers, precondensers and intercondensers, system cost efficiency can be optimized. Vacuum-condensing systems permit reclamation of high-value product by use of a precondenser, or reduce operating costs with intercondensers. A precondenser placed between the vacuum vessel and ejector system will recover valuable process vapors and reduce vapor load to an ejector system--minimizing the system`s capital and operating costs. Similarly, an intercondenser positioned between ejector stages can condense motive steam and process vapors and reduce vapor load to downstream ejectors as well as lower capital and operating costs. The paper describes vacuum condenser systems, types of vacuum condensers, shellside condensing, tubeside condensing, noncondensable gases, precondenser pressure drop, system interdependency, equipment installation, and equipment layout.

Lines, J.R.; Tice, D.W. [Graham Mfg. Co., Batavia, NY (United States)

1997-09-01

389

Inertization of pyrite cinders and co-inertization with electric arc furnace flue dusts by pyroconsolidation at solid state  

Microsoft Academic Search

The viability of a pyroconsolidation process to render pyrite cinders inert and to co-inert pyrite cinders with a hazardous polymetallic residue such as electric arc furnace flue dusts (EAF) containing Pb, Cu, Zn, As, Cr, Ni and Mo were investigated. The effects of pyroconsolidation temperature (800–1200 °C), milling pyrite cinders and additions of both CaO and EAF on the resulting microstructure

J Vińals; M. J Balart; A Roca

2002-01-01

390

Process and apparatus for igniting a burner in an inert atmosphere  

DOEpatents

According to this invention there is provided a process and apparatus for the ignition of a pilot burner in an inert atmosphere without substantially contaminating the inert atmosphere. The process includes the steps of providing a controlled amount of combustion air for a predetermined interval of time to the combustor then substantially simultaneously providing a controlled mixture of fuel and air to the pilot burner and to a flame generator. The controlled mixture of fuel and air to the flame generator is then periodically energized to produce a secondary flame. With the secondary flame the controlled mixture of fuel and air to the pilot burner and the combustion air is ignited to produce a pilot burner flame. The pilot burner flame is then used to ignited a mixture of main fuel and combustion air to produce a main burner flame. The main burner flame then is used to ignite a mixture of process derived fuel and combustion air to produce products of combustion for use as an inert gas in a heat treatment process.

Coolidge, Dennis W. (Katy, TX) [Katy, TX; Rinker, Franklin G. (Perrysburg, OH) [Perrysburg, OH

1994-01-01

391

Condensation and Evaporation of Solar System Materials  

NASA Astrophysics Data System (ADS)

It is widely believed that the materials making up the solar system were derived from a nebular gas and dust cloud that went through an early high-temperature stage during which virtually all of the material was in the gas phase. At one time, it was thought that the entire inner solar nebula was hot, but it is now believed that most material was processed through regions where high temperatures were achieved. Certainly some material, such as presolar grains (cf., Mendybaev et al., 2002a), has never been exposed to high temperatures. As the system cooled, solids and perhaps liquids began to condense, but at some point the partially condensed materials became isolated from the remaining gas. Various lines of evidence support this view. At the largest scale, there is the observation that the Earth, Moon, Mars, and all chondritic meteorites except for the CI chondrites are depleted to varying degrees in the abundances of moderately volatile elements relative to bulk solar system composition. The CI chondrites reflect the bulk composition of the solar system for all but hydrogen, carbon, nitrogen, oxygen, and the rare gases, the most volatile elements (see Chapter 1.03; Palme et al., 1988; McDonough and Sun, 1995; Humayun and Cassen, 2000). The depletions in moderately volatile elements are, to a significant degree, correlated with condensation temperature, suggesting progressive removal of gas as condensation proceeded ( Cassen, 1996). Additional observations that can be explained by partial condensation are that various particularly primitive components of meteorites (e.g., calcium-, aluminum-rich refractory inclusions, and certain metal grains) have mineralogy and/or details of their chemical composition that are remarkably similar to what is calculated for equilibrium condensates from a solar composition gas. For example, the calcium-, aluminum-rich inclusions (CAIs) in chondritic meteorites have compositions very similar to that calculated for the first 5% of total condensable matter (see Chapter 1.08; Grossman, 1973; Wänke et al., 1974; Grossman and Ganapathy, 1976; Grossman et al., 1977), where CI chondrites are taken to represent total condensable matter.Elemental abundance patterns ordered by volatility certainly could have been produced by partial condensation, but they could also have been caused by partial evaporation. The relative importance of these opposite processes is still subject to debate and uncertainty. It should be remembered that condensation calculations typically assume chemical equilibrium in a closed system, in which case the system has no memory of the path by which it arrived at a given state, and thus the chemical and isotopic composition of the condensed phase cannot be used to distinguish between partial condensation and partial evaporation. Humayun and Clayton (1995) have taken a somewhat different view by arguing that condensation and evaporation are distinguishable, in that evaporation, but not condensation, will produce isotopically fractionated residues. With this idea in mind, they carefully measured the potassium isotopic compositions of a broad range of solar system materials with different degrees of potassium depletion and found them to be indistinguishable. This they took as evidence that evaporation could not have been a significant process in determining the diverse elemental abundance patterns of the various solar system materials they measured, because had evaporation been important in fractionating potassium it would have also fractionated the potassium isotopes. We will qualify this line of reasoning by arguing that evaporation and condensation can under certain conditions produce isotopically fractionated condensed phases (i.e., that partial evaporation can produce isotopically heavy residues and that partial condensation can produce isotopically light condensates) but that under other conditions both can produce elemental fractionations without significant isotopic fractionation. The absence of isotopic fractionation in a volatile element-depleted condensed phase is more a

Davis, A. M.; Richter, F. M.

2003-12-01

392

Analytical Treatment of Normal Condensation Shock  

NASA Technical Reports Server (NTRS)

The condensation of water vapor in an air consequences: acquisition of heat (liberated heat vaporization; loss of mass on the part of the flowing gas (water vapor is converted to liquid); change in the specific gas constants and of the ratio k of the specific heats (caused by change of gas composition). A discontinuous change of state is therefore connected with the condensation; schlieren photographs of supersonic flows in two-dimensional Laval nozzles show two intersecting oblique shock fronts that in the case of high humidities may merge near the point of intersection into one normal shock front.

Heybey

1947-01-01

393

Electrochemical polishing of hydrogen sulfide from coal synthesis gas  

SciTech Connect

An advanced process has been developed for the separation of H{sub 2}S from coal gasification product streams through an electrochemical membrane. This technology is developed for use in coal gasification facilities providing fuel for cogeneration coal fired electrical power facilities and Molten Carbonate Fuel Cell electrical power facilities. H{sub 2}S is removed from the syn-gas by reduction to the sulfide ion and H at the cathode. The sulfide ion migrates to the anode through a molten salt electrolyte suspended in an inert ceramic matrix. Once at the anode it is oxidized to elemental sulfur and swept away for condensation in an inert gas stream. The syn-gas is enriched with the H{sub 2}. Order-of-magnitude reductions in H{sub 2}S have been repeatably recorded (100 ppm to 10 ppm H{sub 2}S) on a single pass through the cell. This process allows removal of H{sub 2}S without cooling the gas stream and with negligible pressure loss through the separator. Since there are no absorbents used, there is no absorption/regeneration step as with conventional technology. Elemental sulfur is produced as a by-product directly, so there is no need for a Claus process for sulfur recovery. This makes the process economically attractive since it is much less equipment intensive than conventional technology.

Gleason, E.F.; Winnick, J.

1995-11-01

394

Bose-Einstein Condensation Measurements and Superflow in Condensed Helium  

NASA Astrophysics Data System (ADS)

We review the formulation and measurement of Bose-Einstein condensation (BEC) in liquid and solid helium. BEC is defined for a Bose gas and subsequently for interacting systems via the one-body density matrix (OBDM) valid for both uniform and non-uniform systems. The connection between the phase coherence created by BEC and superflow is made. Recent measurements show that the condensate fraction in liquid 4He drops from 7.25±0.75 % at saturated vapor pressure ( p?0) to 2.8±0.2 % at pressure p=24 bars near the solidification pressure ( p=25.3 bar). Extrapolation to solid densities suggests a condensate fraction in the solid of 1 % or less, assuming a frozen liquid structure such as an amorphous solid. Measurements in the crystalline solid have not been able to detect a condensate with an upper limit set at n 0?0.3 %. Opportunities to observe BEC directly in liquid 4He confined in porous media, where BEC is localized to patches by disorder, and in amorphous solid helium is discussed.

Glyde, H. R.

2013-09-01

395

PL CONDENSER EVALUATION REPORT  

Microsoft Academic Search

The air-cooled steam condenser and sub-cooler developed for use with the ; PL series of natural circulation boiling water nuclear power plants are designed ; to condense 13,000 lb\\/hr at 10% moisture at 15 in. Hg and to subcool the ; condensate to 100 deg F at an ambient temperature of 60 deg F. The design heat ; load at

V. R. Mardoc; R. G. Young

1961-01-01

396

Efficient condensate removal  

Microsoft Academic Search

Achieving stable control of product temperatures on reboilers and other steam\\/product heat exchangers has long been a problem area where conventional steam control and condensate trapping methods were used. Application of a non-electric condensate pump and steam trap sidesteps the problem. Removal of condenser under all conditions, from full load to zero load, is readily achieved. Steam flow control then

Armer

1988-01-01

397

Condensation in Microchannels  

Microsoft Academic Search

Condensation in microchannels has applications in a wide variety of advanced microthermal devices. Presented here is a review of both experimental and theoretical analyses of condensation in these microchannels, with special attention given to the effects of channel diameter and surface conditions on the flow regimes of condensing flows occurring in these channels. This review suggests that surface tension, rather

Yongping Chen; Mingheng Shi; Ping Cheng; G. P. Peterson

2008-01-01

398

Rydberg excitation of Bose-Einstein condensates.  

PubMed

Rydberg atoms provide a wide range of possibilities to tailor interactions in a quantum gas. Here, we report on Rydberg excitation of Bose-Einstein condensed 87Rb atoms. The Rydberg fraction was investigated for various excitation times and temperatures above and below the condensation temperature. The excitation is locally blocked by the van der Waals interaction between Rydberg atoms to a density-dependent limit. Therefore, the abrupt change of the thermal atomic density distribution to the characteristic bimodal distribution upon condensation could be observed in the Rydberg fraction. The observed features are reproduced by a simulation based on local collective Rydberg excitations. PMID:18232977

Heidemann, Rolf; Raitzsch, Ulrich; Bendkowsky, Vera; Butscher, Björn; Löw, Robert; Pfau, Tilman

2008-01-25

399

Post irradiation examination of uranium inclusions in inert matrices  

Microsoft Academic Search

The inert matrix materials CeO2, MgO, Y2O3, MgAl2O4 and Y3Al5O12 were selected as candidates for inert matrices for the EFTTRA22Experimental Feasibility of Targets for TRAnsmutation, a European project in which CEA, NRG, EdF, FzK, JRC-ITU and JRC-IAM cooperate.-T3 neutron irradiation experiment. Most targets contain 20% enriched 235U fissile inclusions with an average size of roughly 150 ?m. The volume fraction

E. A. C. Neeft; K. Bakker; H. A. Buurveld; J. Minkema; A. Paardekooper; R. P. C. Schram; C. Sciolla; O. Zwaagstra; B. Beemsterboer; J. R. W. Woittiez; P. van Vlaanderen; W. J. Tams; H. Hein; R. Conrad; A. van Veen

2001-01-01

400

Condensate fluctuations of interacting Bose gases within a microcanonical ensemble  

NASA Astrophysics Data System (ADS)

Based on counting statistics and Bogoliubov theory, we present a recurrence relation for the microcanonical partition function for a weakly interacting Bose gas with a finite number of particles in a cubic box. According to this microcanonical partition function, we calculate numerically the distribution function, condensate fraction, and condensate fluctuations for a finite and isolated Bose-Einstein condensate. For ideal and weakly interacting Bose gases, we compare the condensate fluctuations with those in the canonical ensemble. The present approach yields an accurate account of the condensate fluctuations for temperatures close to the critical region. We emphasize that the interactions between excited atoms turn out to be important for moderate temperatures.

Wang, Jianhui; He, Jizhou; Ma, Yongli

2011-05-01

401

Dipolar Bose-Einstein condensates at finite temperature  

NASA Astrophysics Data System (ADS)

We study a Bose-Einstein condensate of a dilute gas with dipolar interactions, at finite temperature, using the Hartree-Fock-Bogoliubov theory within the Popov approximation. An additional approximation involving the dipolar exchange interaction is made to facilitate the computation. We calculate the temperature dependence of the condensate fraction of a condensate confined in a cylindrically symmetric harmonic trap. We show that the biconcave-shaped condensates found in [Ronen Phys. Rev. Lett. 98, 30406 (2007)] in certain pancake traps at zero temperature are also stable at finite temperature. Surprisingly, the dip in the central density of these structured condensates is actually enhanced at low finite temperatures. We explain this effect.

Ronen, Shai; Bohn, John L.

2007-10-01

402

Gas shielding apparatus  

DOEpatents

An apparatus for preventing oxidation by uniformly distributing inert shielding gas over the weld area of workpieces such as pipes being welded together. The apparatus comprises a chamber and a gas introduction element. The chamber has an annular top wall, an annular bottom wall, an inner side wall and an outer side wall connecting the top and bottom walls. One side wall is a screen and the other has a portion defining an orifice. The gas introduction element has a portion which encloses the orifice and can be one or more pipes. The gas introduction element is in fluid communication with the chamber and introduces inert shielding gas into the chamber. The inert gas leaves the chamber through the screen side wall and is dispersed evenly over the weld area.

Brandt, Daniel (Los Alamos, NM)

1985-01-01

403

Exhaust gas treatment in testing nuclear rocket engines  

SciTech Connect

With the exception of the last test series of the Rover program, Nuclear Furnace 1, test-reactor and rocket engine hydrogen gas exhaust generated during the Rover/NERVA program was released directly to the atmosphere, without removal of the associated fission products and other radioactive debris. Current rules for nuclear facilities (DOE Order 5480.6) are far more protective of the general environment; even with the remoteness of the Nevada Test Site, introduction of potentially hazardous quantities of radioactive waste into the atmosphere must be scrupulously avoided. The Rocketdyne treatment concept features a diffuser to provide altitude simulation and pressure recovery, a series of heat exchangers to gradually cool the exhaust gas stream to 100 K, and an activated charcoal bed for adsorption of inert gases. A hydrogen-gas fed ejector provides auxiliary pumping for startup and shutdown of the engine. Supplemental filtration to remove particulates and condensed phases may be added at appropriate locations in the system. The clean hydrogen may be exhausted to the atmosphere and flared, or the gas may be condensed and stored for reuse in testing. The latter approach totally isolates the working gas from the environment.

Zweig, H.R.; Fischler, S.; Wagner, W.R. (Rocketdyne Division, Rockwell International Corporation, 6633 Canoga Avenue, P.O. Box 7922, Canoga Park, California 91309-7922 (United States))

1993-01-15

404

Exhaust gas treatment in testing nuclear rocket engines  

NASA Astrophysics Data System (ADS)

With the exception of the last test series of the Rover program, Nuclear Furnace 1, test-reactor and rocket engine hydrogen gas exhaust generated during the Rover/NERVA program was released directly to the atmosphere, without removal of the associated fission products and other radioactive debris. Current rules for nuclear facilities (DOE Order 5480.6) are far more protective of the general environment; even with the remoteness of the Nevada Test Site, introduction of potentially hazardous quantities of radioactive waste into the atmosphere must be scrupulously avoided. The Rocketdyne treatment concept features a diffuser to provide altitude simulation and pressure recovery, a series of heat exchangers to gradually cool the exhaust gas stream to 100 K, and an activated charcoal bed for adsorption of inert gases. A hydrogen-gas fed ejector provides auxiliary pumping for startup and shutdown of the engine. Supplemental filtration to remove particulates and condensed phases may be added at appropriate locations in the system. The clean hydrogen may be exhausted to the atmosphere and flared, or the gas may be condensed and stored for reuse in testing. The latter approach totally isolates the working gas from the environment.

Zweig, Herbert R.; Fischler, Stanley; Wagner, William R.

1993-01-01

405

Determination of Ethane-1,2-diamine in Inert Complexes.  

ERIC Educational Resources Information Center

Describes a procedure for determining ethane-1,2-diamine (EN) which is generally applicable for inert or labile complexes or for EN in its salts, although it cannot be used directly with ammonium or coordinated ammonia. It gives results with five percent accuracy or better and requires less than one hour laboratory time. (JN)

Searle, Graeme H.

1985-01-01

406

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...e. , zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2011-07-01

407

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...i.e. zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2000-07-01

408

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...e. , zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2010-07-01

409

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...e. , zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2012-07-01

410

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...i.e. zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2001-07-01

411

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...i.e. zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2002-07-01

412

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...e. , zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2008-07-01

413

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...i.e. zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2004-07-01

414

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...e. , zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2007-07-01

415

33 CFR 154.824 - Inerting, enriching, and diluting systems.  

Code of Federal Regulations, 2010 CFR

...vacuum relief valves, or other devices which could allow air into...i.e. zirconia oxide or thermomagnetic) must not be used. (h...and (4) If a combustion device is used to produce the inert...valve between the combustion device and the vapor collection...

2003-07-01

416

The inert doublet model: an archetype for dark matter  

Microsoft Academic Search

The inert doublet model (IDM), a two Higgs extension of the standard model with an unbroken Z2 symmetry, is a simple and yet rich model of dark matter. We present a systematic analysis of the dark matter abundance and investigate the potentialities for direct and gamma indirect detection. We show that the model should be within the range of future

Laura Lopez Honorez; Emmanuel Nezri; Josep F. Oliver; Michel H. G. Tytgat

2007-01-01

417

Preliminary Design Report, Shippingport Spent Fuel Drying and Inerting System.  

National Technical Information Service (NTIS)

A process description and system flow sheets have been prepared to support the design/build package for the Shippingport Spent Fuel Canister (SSFC) drying and inerting process skid. A process flow diagram was prepared to show the general steps to dry and ...

2002-01-01

418

Inert Electrodes Program fiscal year 1988 annual report  

SciTech Connect

The Inert Electrodes Program, being conducted by Pacific Northwest Laboratory (PNL), involves improving the Hall-Heroult cells used by the Aluminum Industry for the electrochemical production of aluminum. The PNL research centers on developing more energy efficient, longer-lasting anodes and cathodes and ancillary equipment. Major accomplishments for Fiscal Year 1988 are summarized below. 14 refs., 56 figs., 9 tabs.

Strachan, D.M.; Marschman, S.C.; Davis, N.C.; Friley, J.R.; Schilling, C.H.

1989-10-01

419

Optical Third-Harmonic Coefficients for the Inert Gases.  

National Technical Information Service (NTIS)

Optical third-harmonic coefficients are calculated for the inert gases and are compared with recent experimental values. They were found to range from 0.9 x 10 to the 39th power esu/atom for He to 222 x 10 to the 39th power esu/atom for Xe. The calculated...

E. L. Dawes

1967-01-01

420

Combustion of hydrocarbon fuels within porous inert media  

Microsoft Academic Search

There has been a recent surge of interest in the combustion of hydrocarbon fuels within porous inert media. The interest has been directed by the needs of industry to develop high performance radiant heaters while complying with increasingly stringent emissions regulations. This paper reviews the processes associated with non-catalytic combustion within porous media, and describes related experimental and modeling research.

J. R. Howell; M. J. Hall; J. L. Ellzey

1996-01-01

421

Direct conversion of natural gas to methanol by controlled oxidation  

Microsoft Academic Search

A process is described for converting natural gas containing methane to methanol, comprising: thoroughly and intimately mixing natural gas with gaseous air or oxygen to achieve substantially complete homogeneity of these gases; feeding the resulting gas mixture to an inert reactor under elevated pressure, the inert reactor having an internal surface surrounding a zone in which the gases react. The

H. D. Gesser; N. R. Hunter; L. Morton

1986-01-01

422

CONDENSED MATTER: STRUCTURE, THERMAL AND MECHANICAL PROPERTIES: High density gas state at water/graphite interface studied by molecular dynamics simulation  

NASA Astrophysics Data System (ADS)

In this paper molecular dynamics simulations are performed to study the accumulation behaviour of N2 and H2 at water/graphite interface under ambient temperature and pressure. It finds that both N2 and H2 molecules can accumulate at the interface and form one of two states according to the ratio of gas molecules number to square of graphite surface from our simulation results: gas films (pancake-like) for a larger ratio and nanobubbles for a smaller ratio. In addition, we discuss the stabilities of nanobubbles at different environment temperatures. Surprisingly, it is found that the density of both kinds of gas states can be greatly increased, even comparable with that of the liquid N2 and liquid H2. The present results are expected to be helpful for the understanding of the stable existence of gas film (pancake-like) and nanobubbles.

Wang, Chun-Lei; Li, Zhao-Xia; Li, Jing-Yuan; Xiu, Peng; Hu, Jun; Fang, Hai-Ping

2008-07-01

423

Dynamics of capillary condensation in lattice gas models of confined fluids: A comparison of dynamic mean field theory with dynamic Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

This article addresses the accuracy of a dynamic mean field theory (DMFT) for fluids in porous materials [P. A. Monson, J. Chem. Phys. 128, 084701 (2008)]. The theory is used to study the relaxation processes of fluids in pores driven by step changes made to a bulk reservoir in contact with the pore. We compare the results of the DMFT to those obtained by averaging over large numbers of dynamic Monte Carlo (DMC) simulation trajectories. The problem chosen for comparison is capillary condensation in slit pores, driven by step changes in the chemical potential in the bulk reservoir and involving a nucleation process via the formation of a liquid bridge. The principal difference between the DMFT results and DMC is the replacement of a distribution of nucleation times and location along the pore for the formation of liquid bridges by a single time and location. DMFT is seen to yield an otherwise qualitatively accurate description of the dynamic behavior.

Edison, John R.; Monson, Peter A.

2013-06-01

424

ACTIVE MEDIA: Feasibility of the construction of an electric-discharge excimer laser with a condensed rare gas as the active medium  

NASA Astrophysics Data System (ADS)

The feasibility of stimulated emission from solid or liquid rare gases (RG) is considered, particularly in the case of xenon pumped by an electric discharge. An analysis is made of the possibility of establishing a homogeneous electric discharge in a liquid or a crystal in such a way that the bulk of the discharge energy is used to excite RG2 excitons. It should be possible to reach a laser output power of 30 kW in the form of pulses up to 1 ms in duration and the efficiency should be up to 30%. The estimates obtained and an analysis of the published data show that the construction of efficient excimer lasers with condensed xenon, krypton, or argon as the active medium (emitting at wavelengths of 172, 145, and 128 nm, respectively) is not only possible in principle, but should be realisable in practice.

Gordon, Evgenii B.; Rzhevskii, O. S.; Khmelenko, V. V.

1994-03-01

425

Coherent dynamics of Bose-Einstein condensates in high-finesse optical cavities  

Microsoft Academic Search

We study the mutual interaction of a Bose-Einstein condensed gas with a single mode of a high-finesse optical cavity. We show how the cavity transmission reflects condensate properties, and calculate the self-consistent intracavity light field and condensate evolution. Solving the coupled condensate-cavity equations we find that while falling through the cavity, the condensate is adiabatically transfered into the ground state

Peter Horak; Stephen M. Barnett; Helmut Ritsch

2000-01-01

426

Condensed Matter Physics  

NSDL National Science Digital Library

Founded in 1993 by the Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, the journal Condensed Matter Physics is a peer-reviewed, English-language journal covering such aspects of condensed matter as phase transition theory, statistical mechanics of spin and spin-electron systems, metals and alloys, liquids, solutions, electrolytes, surface phenomena, and plasma physics. Selected issues of Condensed Matter Physics from January 1994 to March 2000 are now available free, online in LaTeX format.

427

Disequilibrium condensation environments in space - A frontier in thermodynamics  

NASA Technical Reports Server (NTRS)

The thermal-disequilibrium aspect of the problem of dust-particle formation from a gas phase in an open space environment is discussed in an effort to draw attention to the space condensation environment as an interesting arena for application and extension of the ideas and formalisms of nonequilibrium thermodynamics. It is shown that quasi-steady states with a disequilibrium between the gas-phase kinetic temperature and the condensed-phase internal temperature appear to be the norm of condensation environments in space. Consideration of the case of condensation onto a bulk condensed phase indicates that these quasi-steady states may constitute Prigogine dissipative structures. It is suggested that a proper study of the process of condensation in a space environment should include any effects arising from thermal disequilibrium.

De, B. R.

1979-01-01

428

Condensation Front Migration in a Protoplanetary Nebula  

NASA Technical Reports Server (NTRS)

Condensation front dynamics are investigated in the mid-solar nebula region. A quasi-steady model of the evolving nebula is combined with equilibrium vapor pressure curves to determine evolutionary condensation fronts for selected species. These fronts are found to migrate inwards from the far-nebula to final positions during a period of 10(exp 7) years. The physical process governing this movement is a combination of local viscous heating and luminescent heating from the central star. Two luminescent heating models are used and their effects on the ultimate radial position of the condensation front are discussed. At first the fronts move much faster than the nebular accretion velocity, but after a time the accreting gas and dust overtakes the slowing condensation front.

Davis, Sanford S.

2004-01-01

429

Vortex-antivortex pair in a Bose-Einstein condensate. Type-II quantum lattice gas as a nonlinear ?4 theory of a complex field  

NASA Astrophysics Data System (ADS)

Presented is a type-II quantum algorithm for superfluid dynamics, used to numerically predict solutions of the GP equation for a complex scalar field (spinless bosons) in ?4 theory. The GP equation is a long wavelength effective field theory of a microscopic quantum lattice gas with nonlinear state reduction. The quantum lattice gas algorithm for modeling the dynamics of the one-body BEC state in 3+1 dimensions is presented. To demonstrate the method's strength as a computational physics tool, a difficult situation of filamentary singularities is simulated, the dynamics of solitary vortex-antivortex pairs, which are a basic building block of morphologies of quantum turbulence.

Yepez, J.; Vahala, G.; Vahala, L.

2009-04-01

430

Bose-Einstein condensate general relativistic stars  

NASA Astrophysics Data System (ADS)

We analyze the possibility that due to their superfluid properties some compact astrophysical objects may contain a significant part of their matter in the form of a Bose-Einstein condensate. To study the condensate we use the Gross-Pitaevskii equation with arbitrary nonlinearity. By introducing the Madelung representation of the wave function, we formulate the dynamics of the system in terms of the continuity and hydrodynamic Euler equations. The nonrelativistic and Newtonian Bose-Einstein gravitational condensate can be described as a gas, whose density and pressure are related by a barotropic equation of state. In the case of a condensate with quartic nonlinearity, the equation of state is polytropic with index one. In the framework of the Thomas-Fermi approximation the structure of the Newtonian gravitational condensate is described by the Lane-Emden equation, which can be exactly solved. The case of the rotating condensate is briefly discussed. General relativistic configurations with quartic nonlinearity are studied numerically with both nonrelativistic and relativistic equations of state, and the maximum mass of the stable configuration is determined. Condensates with particle masses of the order of two neutron masses (Cooper pair) and scattering length of the order of 10-20 fm have maximum masses of the order of 2M?, maximum central density of the order of 0.1-0.3×1016g/cm3 and minimum radii in the range of 10-20 km. In this way we obtain a large class of stable astrophysical objects, whose basic astrophysical parameters (mass and radius) sensitively depend on the mass of the condensed particle, and on the scattering length. We also propose that the recently observed neutron stars with masses in the range of 2-2.4M? are Bose-Einstein condensate stars. We discuss the connection of our results with previous boson star models based on scalar field theory.

Chavanis, Pierre-Henri; Harko, Tiberiu

2012-09-01

431

Incorporated evaporative condenser  

Microsoft Academic Search

The incorporated evaporative condenser developed in this work comprises of a system of fins, basin of water condensates, circuit pump and system of drop cloud via spraying. In the whole provision a system of drop collector is also included for the minimisation of water escapes now essential for the operation of system. Actually, the present work aims on the development

Michalis Gr. Vrachopoulos; Andronikos E. Filios; Georgios T. Kotsiovelos; Eleftherios D. Kravvaritis

2007-01-01

432

Inert-sterile neutrino: Cold or warm dark matter candidate  

SciTech Connect

In usual particle models, sterile neutrinos can account for the dark matter of the Universe only if they have masses in the keV range and are warm dark matter. Stringent cosmological and astrophysical bounds, in particular, imposed by x-ray observations, apply to them. We point out that in a particular variation of the inert doublet model, sterile neutrinos can account for the dark matter in the Universe and may be either cold or warm dark matter candidates, even for masses much above the keV range. These inert-sterile neutrinos, produced nonthermally in the early Universe, would be stable and have very small couplings to standard model particles, rendering very difficult their detection in either direct or indirect dark matter searches. Their existence could be revealed only by discovering other particles of the model in collider experiments.

Gelmini, Graciela B.; Osoba, Efunwande [Department of Physics and Astronomy, UCLA, 475 Portola Plaza, Los Angeles, California 90095 (United States); Palomares-Ruiz, Sergio [Centro de Fisica Teorica de Particulas (CFTP), Instituto Superior Tecnico, P-1049-001, Lisboa (Portugal)

2010-03-15

433

Freeze-Tolerant Condensers  

NASA Technical Reports Server (NTRS)

Two condensers designed for use in dissipating heat carried by working fluids feature two-phase, self-adjusting configurations such that their working lengths automatically vary to suit their input power levels and/or heat-sink temperatures. A key advantage of these condensers is that they can function even if the temperatures of their heat sinks fall below the freezing temperatures of their working fluids and the fluids freeze. The condensers can even be restarted from the frozen condition. The top part of the figure depicts the layout of the first condenser. A two-phase (liquid and vapor) condenser/vapor tube is thermally connected to a heat sink typically, a radiatively or convectively cooled metal panel. A single-phase (liquid) condensate-return tube (return artery) is also thermally connected to the heat sink. At intervals along their lengths, the condenser/vapor tube and the return artery are interconnected through porous plugs. This condenser configuration affords tolerance of freezing, variable effective thermal conductance (such that the return temperature remains nearly constant, independently of the ultimate sink temperature), and overall pressure drop smaller than it would be without the porous interconnections. An additional benefit of this configuration is that the condenser can be made to recover from the completely frozen condition either without using heaters, or else with the help of heaters much smaller than would otherwise be needed. The second condenser affords the same advantages and is based on a similar principle, but it has a different configuration that affords improved flow of working fluid, simplified construction, reduced weight, and faster recovery from a frozen condition.

Crowley, Christopher J.; Elkouhk, Nabil

2004-01-01

434

A Gerdien condenser system for measuring stratospheric charged particle densities  

NASA Astrophysics Data System (ADS)

A Gerdien condenser system for measuring stratospheric charged particles densities is described. The system makes use of commercially available blowers to obtain the bulk gas flow through the condenser and a time of charge method for measuring collected currents. System modifications made over several balloon flights are described and the results of one flight are presented in some detail.

Sherman, C.; Bailey, A. D.; Borghetti, J.

1984-02-01

435

Evolution of weak disturbances in inert binary mixtures  

NASA Technical Reports Server (NTRS)

The evolution of weak disturbances in inert binary mixtures is determined for the one-dimensional piston problem. The interaction of the dissipative and nonlinear mechanisms is described by Burgers' equation. The binary mixture diffusion mechanisms enter as an additive term in an effective diffusivity. Results for the impulsive motion of a piston moving into an ambient medium and the sinusoidally oscillating piston are used to illustrate the results and elucidate the incorrect behavior pertaining to the associated linear theory.

Rasmussen, M. L.

1977-01-01

436

Yttrium stabilised zirconia inert matrix fuel irradiation at an international research reactor  

NASA Astrophysics Data System (ADS)

Different concepts have been developed during the last decade to transmute transuranium elements (TRU) using uranium-free inert matrix fuels (IMF) in a once-through-cycle to reduce the amount of TRU in the nuclear waste. For today's LWRs yttrium stabilised zirconia (YSZ) and other oxides like alumina, spinel or ceria have been proposed as inert matrix materials. By employing IMF, a larger fraction of plutonium can potentially be consumed in comparison with MOX fuels without breeding new plutonium. The aim of the presented study is to measure the general thermal behaviour of YSZ-based IMF under irradiation conditions similar to those in current LWRs in direct comparison to standard MOX fuel. Of particular interest are the fuel thermal conductivity (and its degradation with burnup), fission gas release (FGR), fuel densification and fuel swelling. A secondary aim is the direct comparison of the fuel performance between YSZ-based IMF and MOX fuel. The irradiation is performed under HBWR conditions and has reached an average assembly burnup of ˜300 kW d cm -3 until the end of 2004, which is equivalent to ˜29 MW d kg -1 for the MOX fuel.

Streit, M.; Wiesenack, W.; Tverberg, T.; Hellwig, Ch.; Oberländer, B. C.

2006-06-01

437

Study of Thermo-Acoustic Instabilities in a Rijke Tube Without and With Porous Inert Medium  

NASA Astrophysics Data System (ADS)

Porous inert medium has been used in the past to reduce combustion noise in atmospheric pressure systems. It is envisioned that this same approach could be used to mitigate combustion instabilities encountered in gas turbines using lean premixed combustion concept. In this study, a simple Rijke tube is used to investigate the effect of porous inert media on thermo-acoustic instabilities. The Rijke tube set up utilizes a simple tube with a localized heat source. Sound pressure level measurements are taken at the tube exit to determine the sound power spectra in decibels. Such measurements were taken without and with porous medium inserted within the Rijke tube. The porous media is a 2.54 cm thick ceramic disk with 10 to 20 pores per inch. Results show that the Rijke tube behavior without the porous media follows the trends observed by previous investigators. The porous media was effective in reducing the sound pressure level, and thus, it offers the potential to mitigate thermo-acoustic instabilities through proper geometric design.

Osmer, Cody; Agrawal, Ajay

2010-11-01

438

The Optimum Plutonium Inert Matrix Fuel Form for Reactor-Based Plutonium Disposition  

SciTech Connect

The University of Florida has underway an ongoing research program to validate the economic, operational and performance benefits of developing an inert matrix fuel (IMF) for the disposition of the U.S. weapons plutonium (Pu) and for the recycle of reprocessed Pu. The current fuel form of choice for Pu disposition for the Department of Energy is as a mixed oxide (MOX) (PuO2/UO2). We will show analyses that demonstrate that a Silicon Carbide (SiC) IMF offers improved performance capabilities as a fuel form for Pu recycle and disposition. The reason that UF is reviewing various materials to serve as an inert matrix fuel is that an IMF fuel form can offer greatly reduced Pu and transuranic isotope (TRU) production and also improved thermal performance characteristics. Our studies showed that the Pu content is reduced by an order of magnitude while centerline fuel temperatures are reduced approximately 380 degrees centigrade compared to MOX. These reduced temperatures result in reduced stored heat and thermal stresses in the pellet. The reduced stored heat reduces the consequences of the loss of coolant accident, while the reduced temperatures and thermal stresses yield greatly improved fuel performance. Silicon Carbide is not new to the nuclear industry, being a basic fuel material in gas cooled reactors.

Tulenko, J.S.; Wang, J.; Acosta, C.

2004-10-06

439

The Optimum Plutonium Inert Matrix Fuel Form for Reactor-Based Plutonium Disposition  

SciTech Connect

The University of Florida has underway an ongoing research program to validate the economic, operational and performance benefits of developing an inert matrix fuel (IMF) for the disposition of the U.S. weapons plutonium (Pu) and for the recycle of reprocessed Pu. The current fuel form of choice for Pu disposition for the Department of Energy is as a mixed oxide (MOX) (PuO2/UO2). We will show analyses that demonstrate that a Silicon Carbide (SiC) IMF offers improved performance capabilities as a fuel form for Pu recycle and disposition. The reason that UF is reviewing various materials to serve as an inert matrix fuel is that an IMF fuel form can offer greatly reduced Pu and transuranic isotope (TRU) production and also improved thermal performance characteristics. Our studies showed that the Pu content is reduced by an order of magnitude while centerline fuel temperatures are reduced approximately 380 degrees centigrade compared to MOX. These reduced temperatures result in reduced stored heat and thermal stresses in the pellet. The reduced stored heat reduces the consequences of the loss of coolant accident, while the reduced temperatures and thermal stresses yield greatly improved fuel performance. Silicon Carbide is not new to the nuclear industry, being a basic fuel material in gas cooled reactors.

Tulenko, J.S.; Wang, J.; Acosta, C.

2004-10-03

440

Kinetics of switch grass pellet thermal decomposition under inert and oxidizing atmospheres.  

PubMed

Grass pellets are a renewable resource that have energy content similar to that of wood. However, the higher ash and chlorine content affects combustion. Thermal degradation analysis of a fuel is useful in developing effective combustion. Thermogravimetric analysis (TGA) of the thermal degradation of grass pellets under inert (nitrogen) and oxidizing (air) atmospheres was conducted. Non-isothermal conditions were employed with 4 different heating rates. Kinetic parameters (activation energy and pre-exponential factors) were estimated using the iso-conversional method. Both pyrolysis and oxidative atmospheric thermal degradation exhibited two major loss process: volatilization of cellulose, hemicelluloses and lignin and burning or slow oxidation of the residual char. The activation energy and pre-exponential factors were high for the oxidizing environment. During pyrolysis, major decomposition occurred with 40% to 75% conversion of the mass to gas with an activation energy of 314 kJ/mol. In air the decomposition occurred with 30% to 55% conversion with an activation energy of 556 kJ/mol. There was a substantial effect of heating rate on mass loss and mass loss rate. The TG shifted to higher temperature ranges on increasing the heating rate. In both pyrolyzing and oxidizing conditions, average combustion and devolatilization rates increased. Enhanced combustion takes place with higher activation energy in oxidizing atmosphere compared to the inert atmosphere due to presence of air. PMID:23026316

Chandrasekaran, Sriraam R; Hopke, Philip K

2012-12-01

441

Condensation in the primitive solar nebula  

Microsoft Academic Search

The distribution of the major elements between vapor and solid has been calculated for a cooling gas of cosmic composition. The assumption is made that high temperature condensates remain in equilibrium with the vapor, affecting the temperatures of appearance of successively less refractory phases. The model suggests that the major textural features and mineralogical composition of the Ca, Al-rich inclusions

Lawrence Grossman

1972-01-01

442

CONDENSED MATTER: STRUCTURE, THERMAL AND MECHANICAL PROPERTIES: High density gas state at water\\/graphite interface studied by molecular dynamics simulation  

Microsoft Academic Search

In this paper molecular dynamics simulations are performed to study the accumulation behaviour of N2 and H2 at water\\/graphite interface under ambient temperature and pressure. It finds that both N2 and H2 molecules can accumulate at the interface and form one of two states according to the ratio of gas molecules number to square of graphite surface from our simulation

Chun-Lei Wang; Zhao-Xia Li; Jing-Yuan Li; Peng Xiu; Jun Hu; Hai-Ping Fang

2008-01-01

443

Electron-induced damage of biotin studied in the gas phase and in the condensed phase at a single-molecule level  

NASA Astrophysics Data System (ADS)

Biotin is an essential vitamin that is, on the one hand, relevant for the metabolism, gene expression and in the cellular response to DNA damage and, on the other hand, finds numerous applications in biotechnology. The functionality of biotin is due to two particular sub-structures, the ring structure and the side chain with carboxyl group. The heterocyclic ring structure results in the capability of biotin to form strong intermolecular hydrogen and van der Waals bonds with proteins such as streptavidin, whereas the carboxyl group can be employed to covalently bind biotin to other complex molecules. Dissociative electron attachment (DEA) to biotin results in a decomposition of the ring structure and the carboxyl group, respectively, within resonant features in the energy range 0-12 eV, thereby preventing the capability of biotin for intermolecular binding and covalent coupling to other molecules. Specifically, the fragment anions (M-H)-, (M-O)-, C3N2O-, CH2O2-, OCN-, CN-, OH- and O- are observed, and exemplarily the DEA cross section of OCN- formation is determined to be 3 × 10-19 cm2. To study the response of biotin to electrons within a complex condensed environment, we use the DNA origami technique and determine a dissociation yield of (1.1 ± 0.2) × 10-14 cm2 at 18 eV electron energy, which represents the most relevant energy for biomolecular damage induced by secondary electrons. The present results thus have important implications for the use of biotin as a label in radiation experiments.

Keller, Adrian; Kopyra, Janina; Gothelf, Kurt V.; Bald, Ilko

2013-08-01

444

Reduced temperature aluminum production in an electrolytic cell having an inert anode  

DOEpatents

Aluminum is produced by electrolytic reduction of alumina in a cell having a cathode, an inert anode and a molten salt bath containing metal fluorides and alumina. The inert anode preferably contains copper, silver and oxides of iron and nickel. Reducing the molten salt bath temperature to about 900-950.degree. C. lowers corrosion on the inert anode constituents.

Dawless, Robert K. (Monroeville, PA); Ray, Siba P. (Murrysville, PA); Hosler, Robert B. (Sarver, PA); Kozarek, Robert L. (Apollo, PA); LaCamera, Alfred F. (Trafford, PA)

2000-01-01

445

The performance improvements of train suspension systems with mechanical networks employing inerters  

Microsoft Academic Search

This paper investigates the performance benefits of train suspension systems employing a new mechanical network element called an inerter. An inerter is a true mechanical two-terminal element with the applied force proportional to the relative acceleration across the terminals. Until now, ideal inerters have been applied to car and motorcycle suspension systems, for which a significant performance improvement was reported.

Fu-Cheng Wang; Min-Kai Liao; Bo-Huai Liao; Wei-Jiun Su; Hsiang-An Chan

2009-01-01

446

Unidentified Inert Ingredients in Pesticides: Implications for Human and Environmental Health  

Microsoft Academic Search

BACKGROUND: By statute or regulation in the United States and elsewhere, pesticide ingredients are divided into two categories: active and inert (sometimes referred to as other ingredients, adjuvants, or coformulants). Despite their name, inert ingredients may be biologically or chemically active and are labeled inert only because of their function in the formulated product. Most of the tests required to

Caroline Cox; Michael Surgan

2006-01-01

447

Theoretical analysis of condensation in the presence of noncondensable gases as applied to open cycle OTEC condensers  

Microsoft Academic Search

The open cycle ocean thermal energy conversion condenser was analyzed from a theoretical standpoint. Interfacial temperature profiles and gas concentrations in the axial direction were determined, and their effects on the rate of condensation studied. For the analysis, the vapor phase was modeled using diffusion equations for simultaneous heat and mass transfer processes, while the liquid phase was modeled using

C. B. Panchal; K. J. Bell

1984-01-01

448

Asymptotic Behavior of Rotating Rarefied Gases with Evaporation and Condensation.  

National Technical Information Service (NTIS)

The asymptotic behavior of the cylindrical Couette flow problem for a rarefied rotating gas with evaporation and condensation is studied when the state of equilibrium is perturbed by the following small thermodynamic forces: (i) the pressure difference of...

L. M. Cumin G. M. Kremer F. Sharipov

2000-01-01

449

Reversible Formation of a Bose-Einstein Condensate  

Microsoft Academic Search

We present a method of adiabatically changing the local phase-space density of an ultracold gas using a combination of magnetic and optical forces. Applying this method, we observe phase-space density increases in a gas of sodium atoms by as much as 50-fold. The transition to Bose-Einstein condensation was crossed reversibly, attaining condensate fractions of up to 30%. Measurements of the

D. M. Stamper-Kurn; H.-J. Miesner; A. P. Chikkatur; S. Inouye; J. Stenger; W. Ketterle

1998-01-01

450

THE COLOR GLASS CONDENSATE.  

SciTech Connect

The Color Glass Condensate is a state of high density gluonic matter which controls the high energy limit of hadronic interactions. Its properties are important for the initial conditions for matter produced at RHIC.

MCLERRAN,L.

2001-08-26

451

Key condenser failure mechanisms  

SciTech Connect

Eight practical lessons highlight many of the factors that can influence condenser tube corrosion at coal-fired utilities and the effects contaminant in-leakage can have on steam generating units. 1 ref., 4 figs.

Buecker, B.

2009-04-15

452

Forecasting Aircraft Condensation Trails.  

National Technical Information Service (NTIS)

Aircraft condensation trails (contrails) are caused by aircraft aerodynamics or engine exhaust in the proper atmospheric conditions. Engine-exhaust trails are the most common and are discussed in this report. Jet aircraft contrail-formation graphs facilit...

1981-01-01

453

Ghost condensate busting  

SciTech Connect

Applying the Thomas-Fermi approximation to renormalizable field theories, we construct ghost condensation models that are free of the instabilities associated with violations of the null-energy condition.

Bilic, Neven [Rudjer Boskovic Institute, 10002 Zagreb (Croatia)] [Rudjer Boskovic Institute, 10002 Zagreb (Croatia); Tupper, Gary B; Viollier, Raoul D, E-mail: bilic@thphys.irb.hr, E-mail: gary.tupper@uct.ac.za, E-mail: raoul.viollier@uct.ac.za [Centre of Theoretical Physics and Astrophysics, University of Cape Town, Rondebosch 7701 (South Africa)

2008-09-15

454

Immobilization of inert TRISO-coated fuel in glass for geological disposal  

NASA Astrophysics Data System (ADS)

Vitrification of TRISO-coated gas reactor fuel particles was achieved via two methods: glass melting and sintering. Inert TRISO-coated fuel particles and a borosilicate glass were used. With glass melting at 1200-1300 °C floatation and decomposition of carbon and silicon carbide occurred. Thermal pre-treatment of the particles for oxidation of pyrocarbon did not improve the coating properties of the glass. During cooling most of the particles floated and sorbed on the crucible or mold walls. The sintered glass at 700 °C showed better coating properties of the TRISO-coated fuel particles despite higher porosity compared to glass made by melting. Aqueous leaching properties of glass with particles are similar regardless the mode of fabrication, indicating the good chemical durability of the sintered glass. Sintered glasses may constitute a good technique for TRISO-coated fuel particles immobilization for an eventual deep geological disposal.

Abdelouas, Abdesselam; Noirault, Samuel; Grambow, Bernd

2006-11-01

455

Condensing furnaces: Lessons from a utility  

SciTech Connect

for the last several years about 90% of the new natural gas furnaces installed in Wisconsin have been condensing furnaces and a number of lessons have been learned. If you avoid the common mistakes, condensing furnaces typically can deliver heating savings of 20-35 % assuming the old furnace was in the 60% AFUE range. This article describes the common mistakes and how to avoid them: outside air needed 100%; benefits of sealed combustion; follow the installation manual scrupulously; how to avoid potential problems; tips on venting.

Beers, J. [Madison Gas and Electric Company, WI (United States)

1994-11-01

456

Molecular exchange and its influence on the condensation coefficient  

NASA Astrophysics Data System (ADS)

When a molecule condenses, it gains kinetic energy which is dissipated by collisions. There is then the possibility that a condensing molecule may kick out a molecule in the interphase or in the liquid. There has been reported a strong correlation between condensation and evaporation fluxes. This ``molecular exchange'' effect is modeled by assuming that certain molecules that condense, kick out one molecule each. In this paper the influence of the molecular exchange mechanism on the condensation coefficient is discussed and it is shown that under certain assumptions, molecular exchange has no effect on gas-kinetic calculations of phase change. However, an expression suitable for molecular dynamics simulations of the fraction of condensing molecules that induces molecular exchange is also derived.

Meland, Roar

2002-10-01

457

Detailed Studies on Flame Extinction by Inert Particles in Normal- and Micro-gravity  

NASA Technical Reports Server (NTRS)

The combustion of dusty flows has been studied to lesser extent than pure gas phase flows and sprays. Particles can have a strong effect by modifying the dynamic response and detailed structure of flames through the dynamic, thermal, and chemical couplings between the two phases. A rigorous understanding of the dynamics and structure of two-phase flows can be attained in stagnation flow configurations, which have been used by others to study spray combustion as well as reacting dusty flows. In earlier studies on reacting dusty flows, the thermal coupling between the two phases as well as the effect of gravity on the flame response were not considered. However, in Ref. 6, the thermal coupling between chemically inert particles and the gas was addressed in premixed flames. The effects of gravity was also studied showing that it can substantially affect the profiles of the particle velocity, number density, mass flux, and temperature. The results showed a strong dynamic and thermal dependence of reacting dusty flows to particle number density. However, the work was only numerical and limited to twin-flames, stagnation, premixed flames. In Ref. 7 the effects of chemically inert particle clouds on the extinction of strained premixed and non-premixed flames were studied both experimentally and numerically at 1-g. It was shown and explained that large particles can cause more effective flame cooling compared to smaller particles. The effects of flame configuration and particle injection orientation were also addressed. The complexity of the coupling between the various parameters in such flows was demonstrated and it was shown that it was impossible to obtain a simple and still meaningful scaling that captured all the pertinent physics.

Andac, M. G.; Egolfopoulos, F. N.; Campbell, C. S.

2001-01-01