1,369 Matching Results

Search Results

Advanced search parameters have been applied.

Composition and thermodynamic properties of air in chemical equilibrium

Description: "Charts have been prepared relating the thermodynamic properties of air in chemical equilibrium for temperatures to 15,000 degrees k and for pressures 10(-5) to 10 (plus 4) atmospheres. Also included are charts showing the composition of air, the isentropic exponent, and the speed of sound. These charts are based on thermodynamic data calculated by the National Bureau of Standards" (p. 1).
Date: April 1958
Creator: Moeckel, W. E. & Weston, Kenneth C.
Partner: UNT Libraries Government Documents Department

Thermal Conductivity of the Helium-Argon System

Description: A semi-empirical relation for the thermal conductivity of helium-argon gas mixtures is suggested. The analyses used in support of the proposed conductivity relations are based on low-temperature (T < 800 degrees C) thermal conductivity data for helium, argon and helium-argon mixtures. The report is a compilation of available data and theories, and does not contain any new experimental results. With the approach presented here, one should be able to predict thermal conductivities of helium-argon mixtures to within 5% of their true values for temperatures up to 1200 K. The recommended equations are best estimates and should be treated as such. A definite need exists for experimental data to verify or modify the recommendation.
Date: February 1979
Creator: Purohit, A. & Moszynski, Jerzy R.
Partner: UNT Libraries Government Documents Department

Probing Late Neutrino Mass Properties With SupernovaNeutrinos

Description: Models of late-time neutrino mass generation contain new interactions of the cosmic background neutrinos with supernova relic neutrinos (SRNs). Exchange of an on-shell light scalar may lead to significant modification of the differential SRN flux observed at earth. We consider an Abelian U(1) model for generating neutrino masses at low scales, and show that there are cases for which the changes induced in the flux allow one to distinguish the Majorana or Dirac nature of neutrinos, as well as the type of neutrino mass hierarchy (normal or inverted or quasi-degenerate). In some region of parameter space the determination of the absolute values of the neutrino masses is also conceivable. Measurements of the presence of these effects may be possible at the next-generation water Cerenkov detectors enriched with Gadolinium, or a 100 kton liquid argon detector.
Date: August 8, 2007
Creator: Baker, Joseph; Goldberg, Haim; Perez, Gilad & Sarcevic, Ina
Partner: UNT Libraries Government Documents Department

Nuclear Shapes at High Angular Momentum

Description: Multiplicities as a function of {gamma}-ray energy have been measured for continuum {gamma}-ray spectra produced in argon- and calcium-induced reactions. A peak sometimes occurs in the multiplicity spectrum, indicating a correlation between {gamma}-ray energy and multiplicity (spin). This correlation can be explained by rotational motion of the nucleus, suggesting basically prolate nuclear shapes. Absence of structure in the multiplicity spectrum is interpreted to indicate non-collective motion, and hence spherical or oblate shapes.
Date: December 1, 1977
Creator: Deleplanque, M.A.; Lee, I.Y.; Stephens, F.S.; Diamond, R.M. & Aleonard, M.M.
Partner: UNT Libraries Government Documents Department

Soft Radiation From Pu²³⁹

Description: "The radiation from Pu²³⁹ have been studied in the region 5-25 keV. For this purpose, a proportional counter, filled with argon to a pressure of 53 cm Hg and with methane to a pressure of 6 cm Hg, was employed in combination with a single-channel pulse analyzer and associated amplifying and counting circuits."
Date: 1952
Creator: Israel, Harvey Ira
Partner: UNT Libraries Government Documents Department

Photoelectron angular distributions beyond the dipole approximation

Description: This paper reports the measurement of nondipolar asymmetry parameters for the angular distributions of Ar 1s, Kr 2s, and Kr 2p photoemission within 2-3 keV above their respective thresholds. Pronounced asymmetries with respect to direction of photon propagation are present even at low electron kinetic energies. The energy dependence of the asymmetry is Z- and subshell-specific and causes the direction of preferred electron emission to change sign at least once in each case. Towards higher energies, the asymmetry increases and the photoelectron emission pattern is forward-skewed for all 3 cases. Measured asymmetry parameters are in good agreement with recent predictions from nonrelativistic calculations which include interference between electric-dipole and electric-quadrupole transition amplitudes in the photoabsorption process.
Date: August 1996
Creator: Kraessig, B.; Jung, M.; Gemmell, D. S.; Kanter, E. P.; LeBrun, T.; Southworth, S. H. et al.
Partner: UNT Libraries Government Documents Department

Star in a jar

Description: A sonoluminescing bubble has been modeled as a thermally conducting, partially ionized two-component plasma. The use of accurate equations-of-state, plasma physics, and radiation physics distinguishes our model from all previous models. The model provides an explanation of many features of single bubble sonoluminescence that have not been collectively accounted for in previous models, including the origin of the picosecond pulse widths and spectra. The calculated spectra for sonoluminescing nitrogen and argon bubbles suggest that a sonoluminescing air bubble probably contains only argon, in agreement with a recent theoretical analysis.
Date: August 11, 1997
Creator: Moss, W.C.; Clarke, D.B. & Young, D.A.
Partner: UNT Libraries Government Documents Department

Effects of O2, Ar, and H2 gases on the field-emission properties of single-walled and multiwalled carbon nanotubes

Description: In this article, the authors compare the effects of O2, Ar, and H2 gases on the field-emission (FE) properties of single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs).
Date: September 17, 2001
Creator: Wadhawan, Atul; Stallcup, Richard E.; Stephens, Kenneth F.; Pérez, José M. & Akwani, Ikerionwu A.
Partner: UNT College of Arts and Sciences

Enhancement of Equilibrium Shift in Dehydrogenation Reactions Using a Novel Membrane Reactor Semi-Annual Report: October 1998-February 1999

Description: Using electroless deposition of palladium thin-films on a microporous ceramic substrate, we developed a hydrogen-selective palladium-ceramic composite membrane. The new membrane has significantly higher permeability and selectivity for hydrogen than many of the commercially available dense-metallic membrane. The hydrogen permeability of the new membrane increases with increasing temperature. These properties make it an ideal candidate for use in membrane reactors to study dehydrogenation reactions by equilibrium shift. To investigate the usefulness of the new membrane in membrane reactor-separator configuration, a model for studying dehydrogenation of cyclohexane by equilibrium in a membrane reactor is developed. Radial diffusion is considered to account for the concentration gradient in the radial direction due to permeation through the membrane. The model is investigated with and without the reaction. In the non-reaction case, a mixture of argon, benzene, cyclohexane, and hydrogen is used in the reaction side and argon is used in the separation side. In the case of dehydrogenation reaction, the feed stream to the reaction side contained hydrogen and argon while in the separation side argon is used as sweep gas. Equilibrium conversion for dehydrogenation of cyclohexane is 18.7%. Present study shows that 100% conversion can be achieved by equilibrium shift using Pd-Ceramic membrane reactor. For a feed containing cyclohexane and argon of 164X10{sup -6} and 1.0x10{sup -3} mol / s, 98% conversion is achieved.
Date: April 30, 1999
Creator: Ilias, Shamsuddin & King, Franklin G.
Partner: UNT Libraries Government Documents Department

Noble gases and cosmogenic radionuclides in the Eltanin Pacific meteorite

Description: A 1.5 cm long, 1.2 g specimen of the Eltanin meteorite was found at 10.97 m depth in Polarstern piston core PS2704-1. The early studies indicated that the small fragments of the Eltanin meteorite was debris from a km-sized asteroid which impacted into the deep-ocean basin. In this study, the authors measured {sup 39}Ar-{sup 40}Ar age, noble gases, and cosmogenic radionuclides in splits of specimen as a part of consortium studies of Eltanin meteorite. They concluded that the specimen was about 3 m deep from the asteroid surface. The exposure age of the Eltanin asteroid was about 20 Myr.
Date: January 14, 2000
Creator: Bogard, D D; Garrison, D H; Caffee, M W; Kyte, F & Nishiizumi, K
Partner: UNT Libraries Government Documents Department


Description: Chemical yields of Fe{sup 3+} have been measured from FeSO{sub 4} solutions irradiated in the presence and absence of oxygen with carbon, neon, and argon ions from the Berkeley Bevalac facility. G(Fe{sup 3+}) decreases with increasing beam penetration and with increasing atomic number of the incident ion. The results are compared with current theoretical expectations of the behavior of these particles in an aqueous absorber. The chemical yields are consistently higher than theoretically predicted, by amounts varying from &lt;6.2% (carbon ions) to &lt;13.2% (argon ions). The additional yields are possibly attributable to fragmentation of the primary particle beams.
Date: July 1, 1980
Creator: Christman, E.A.; Appleby, A. & Jayko, M.
Partner: UNT Libraries Government Documents Department