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Development of nickel-free austenitic stainless steels for ambient and cryogenic applications

Description: A series of alloys have been developed as possible replacements for some austenitic stainless steels. These alloys utilized a Mn substitution for Ni and a reduced Cr concentration from the 18% ordinarily found in the AISI 300 series stainless steels to a concentration of 13%. The base system studied was an alloy containing Fe-16%Mn-13%Cr while other elements added included small additions of N, Si and Mo. A range of microstructures was produced from the alloying additions. The base composition had a triplex (fcc, hcp, bcc) structure while the most highly modified compositions were fully austenitic. Mechanical testing included tensile testing and Charpy V-notch testing conducted at various temperatures between -196/sup 0/C to 23/sup 0/C. Excellent combinations of strength and ductility were obtained (40--65 ksi yield strength, 100--125 ksi ultimate strength, 45--75% elongation and 60--80% reduction of area) at room temperature. Upper shelf energies in Charpy V-notch testing were as high as 185 ft-lbs with a ductile-brittle transition temperature (DBTT) of -160/sup 0/C. Analysis of fracture surfaces determined that alloys without interstitials had no transition in the mode of failure between room temperature and liquid nitrogen temperature. Results of an ASTM sensitization corrosion test, where the experimental alloys were compared to 347 stainless steel, indicated that the alloys were not susceptible to intergranular attack.
Date: February 1, 1978
Creator: Haddick, G.T.; Thompson, L.D.; Parker, E.R. & Zackay, V.F.
Partner: UNT Libraries Government Documents Department

Gas flow through porous barriers

Description: In Part I the possibility of CO/sub 2/ surface diffusion through the porous BaO that results from BaCO/sub 3/ decomposition is examined. CO/sub 2/ and He flow rates through a BaO barrier are compared and both are found to exhibit similar behavior. Because He is known not to undergo surface diffusion, it is concluded that CO/sub 2/ goes through BaO by ordinary Knudsen flow. In Part II the decomposition of SO/sub 3/ to SO/sub 2/ and O/sub 2/ in a porous alumina barrier is studied. The goal is to determine if this reaction will equilibrate in the barrier. A stream of SO/sub 3/ is run through the barrier and the exit gas compositions are determined as a function of temperature with a mass spectrometer. These compositions are found to differ considerably from the calculated equilibrium values, indicating the reaction does not equilibrate in the barrier.
Date: October 1, 1978
Creator: Jacobson, N.S.
Partner: UNT Libraries Government Documents Department

The effect of CO{sub 2} on reservoir behavior for geothermal systems

Description: The purpose was to gain an understanding of the effects of non-condensible gases (CO/sub 2/) in fractured two-phase geothermal systems. A thorough review of previous work on non-condensible gases was carried out. In addition, since the flowing mass fraction of CO/sub 2/ is strongly controlled by the flowing saturation, the flowing enthalpy literature was also reviewed. Numerical techniques were employed to examine how non-condensible gases (CO/sub 2/) affect well transients and to determine the value of these effects as tools to evaluate in situ reservoir parameters. Simplified reservoir models were used to define the effects of CO/sub 2/ in the reservoir and the resulting transient behavior at the feedzones to the well. Furthermore, fracture-matrix interaction was studied in detail to identify the effects of CO/sub 2/ on recovery and flow patterns within the reservoir. The insight gained from the sensitivity studies for enthalpy and CO/sub 2/ transients was applied to interpret transient data from well BR21 at the Broadlands geothermal field of New Zealand.
Date: December 1, 1986
Creator: Gaulke, S.W.
Partner: UNT Libraries Government Documents Department

Shear stress enhancement of void compaction

Description: Since the spherical model was successful in predicting the volumetric compaction behavior of both porous rocks and metals to a uniform pressure, the applicability of the spherical model to nonhydrostatic loading conditions was considered. Specifically, the spherical model is used to examine the influence of the presence of a shear stress on the volumetric compression of a porous solid. First the linear, elastic solution was obtained for a hollow sphere subject to homogeneous tractions on the outer boundary. Then, assuming that the matrix material is governed by the Drucker-Prager yield criterion, the elastic solution was used to derive an analytic expression for the onset of yield in the hollow sphere. The expression for the initial yield surface shows that the presence of a shear stress hastens the onset of yield in the sphere in comparison to a purely hydrostatic loading condition. This result agrees well with experimental data which show that, for porous solids, permanent crush-up begins at a lower mean stress under a nonhydrostatic loading than when the applied loading is a uniform pressure. At this point, due to difficulty in obtaining an analytic solution, a numerical scheme (finite element method) was used to extend the analysis of the hollow sphere problem into the elasto-plastic range. The spherical model results clearly exhibit the experimental finding that the presence of a shear stress tends to enhance the volumetric compaction of porous solids in comparison to a purely hydrostatic loading condition. For both a porous rock and metal sample, agreement between the spherical model and experimental results is excellent.
Date: September 1, 1977
Creator: Curran, J.H. & Carroll, M.M.
Partner: UNT Libraries Government Documents Department

Anomalous electron heating and energy balance in an ion beam generated plasma

Description: The plasma described in this report is generated by a 15 to 34 kV ion beam, consisting primarily of protons, passing through an H/sub 2/ gas cell neutralizer. Plasma ions (or ion-electron pairs) are produced by electron capture from (or ionization of) gas molecules by beam ions and atoms. An explanation is provided for the observed anomalous behavior of the electron temperature (T/sub e/): a step-lite, nearly two-fold jump in T/sub e/ as the beam current approaches that which minimizes beam angular divergence; insensitivity of T/sub e/ to gas pressure; and the linear relation of T/sub e/ to beam energy.
Date: April 1, 1987
Creator: Guethlein, G.
Partner: UNT Libraries Government Documents Department

Modeling of thermodynamic and chemical changes in low-temperature geothermal systems

Description: A method was developed to incorporate the transport of several chemical components into a model of the transport of fluid mass and heat within a geothermal system. It was demonstrated that the use of coupled hydrological, thermal and chemical data allows for the determination of field porosities, amounts and regions of cool recharge into the system as well as field permeabilities and the hot reservoir volume. With the additional information a reliable prediction of the long-term cooling rate can be made.
Date: December 1, 1986
Creator: Spencer, A.L.
Partner: UNT Libraries Government Documents Department

Summary of the working group on high current transport and final focus lenses

Description: The group reviewed recent work, and then addressed itself to relating the current understanding of relevant beam transport effects to the four reference concepts. In addition there was discussion on plans for future experimental and theoretical work. Discussions covered the following topics: (1) Transverse instabilities on intense beams through periodic focusing systems, (2) evaluation and correction of chromatic aberrations in the final beam transport lines, (3) evaluation and correction of geometric aberrations due to quadrupole fringe fields, and (4) ion focusing by electrons.
Date: September 1, 1978
Creator: Garren, A.A.
Partner: UNT Libraries Government Documents Department

Photoionization of atoms and small molecules using synchrotron radiation. [SF/sub 6/, SiF/sub 4/]

Description: The combination of synchrotron radiation and time-of-flight electron spectroscopy has been used to study the photoionization dynamics of atoms (Li) and small molecules (SF/sub 6/, SiF/sub 4/, and SO/sub 2/). Partial cross sections and angular distribution asymmetry parameters have been measured for Auger electrons and photoelectrons as functions of photon energy. Emphasis is on the basic understanding of electron correlation and resonant effects as manifested in the photoemission spectra for these systems. 254 refs., 46 figs., 10 tabs.
Date: November 1, 1986
Creator: Ferrett, T.A.
Partner: UNT Libraries Government Documents Department

Theoretical study of intermolecular energy transfer involving electronically excited molecules: He(/sup 1/S) + H/sub 2/(B /sup 1/. sigma. /sub u//sup +/). [Solution for coupled channel equations]

Description: To further understanding of gas phase collision dynamics involving electronically-excited molecules, a fully quantum mechanical study of He + H/sub 2/(B /sup 1/..sigma../sub u//sup +/) was undertaken. Iterative natural orbital configuration interaction (CI) calculations were performed to obtain the interaction potential between He and H/sub 2/(B /sup 1/..sigma../sub u//sup +/). The potential energy surface (PES) is highly anisotropic and has a van der Waals well of about 0.03 eV for C/sub 2v/ approach. Avoided PES crossings occur with He + H/sub 2/(E,F /sup 1/..sigma../sub g//sup +/) and with He + H/sub 2/(X /sup 1/..sigma../sub g//sup +/) and cause a local maximum and a deep minimum in the He + H/sub 2/(B /sup 1/..sigma../sub u//sup +/) PES, respectively. The crossing with He + H/sub 2/(X /sup 1/..sigma../sub g//sup +/) provides a mechanism for fluorescence quenching. The computed CI energies were combined with previous multi-reference double excitation CI calculations and fit with analytic functions for convenience in scattering calculations. Accurate dipole polarizabilities and quadrupole moment of H/sub 2/(B /sup 1/..sigma../sub u//sup +/) were computed for use in the multipole expansion, which is the analytic form of the long-range PES. 129 refs., 28 figs., 35 tabs.
Date: November 1, 1986
Creator: Grimes, R.M.
Partner: UNT Libraries Government Documents Department

An astrometric search for a stellar companion to the sun

Description: A companion star within 0.8 pc of the Sun has been postulated to explain a possible 26 Myr periodicity in mass extinctions of species on the Earth. Such a star would already be catalogued in the Yale Bright Star catalogue unless it is fainter than m/sub nu/ = 6.5; this limits the possible stellar types for an unseen companion to red dwarfs, brown dwarfs, or compact objects. Red dwarfs account for about 75% of these possible stars. We describe here the design and development of an astrometric search for a nearby red dwarf companion with a six-month peak-to-peak parallax of greater than or equal to2.5 arcseconds. We are measuring the parallax of 2770 candidate faint red stars selected from the Dearborn Observatory catalogue. An automated 30-inch telescope and CCD camera system collect digitized images of the candidate stars, along with a 13' x 16' surrounding field of background stars. Second-epoch images, taken a few months later, are registered to the first epoch images using the background stars as fiducials. An apparent motion, m/sub a/, of the candidate stars is found to a precision of sigma/sub m//sub a/ approx. = 0.08 pixel approx. = 0.2 arcseconds for fields with N/sub fiducial/ greater than or equal to 10 fiducial stars visible above the background noise. This precision is sufficient to detect the parallactic motion of a star at 0.8 pc with a two month interval between the observation epochs. Images with fewer fiducial stars above background noise are observed with a longer interval between epochs. If a star is found with high parallactic motion, we will confirm its distance with further parallax measurements, photometry, and spectral studies, and will measure radial velocity and proper motion to establish its orbit. We have demonstrated the search procedure with observations of 41 stars, and have ...
Date: November 25, 1986
Creator: Perlmutter, S.
Partner: UNT Libraries Government Documents Department

Damage and in-situ annealing during ion implantation

Description: Formation of amorphous (..cap alpha..) layers in Si during ion implantation in the energy range 100 keV-11 MeV and temperature range liquid nitrogen (LN)-100/sup 0/C has been investigated. Cross-sectional transmission electron microscopy (XTEM) shows that buried amorphous layers can be created for both room temperature (RT) and LN temperature implants, with a wider 100 percent amorphous region for the LN cooled case. The relative narrowing of the ..cap alpha.. layer during RT implantation is attributed to in-situ annealing. Implantation to the same fluence at temperatures above 100/sup 0/C does not produce ..cap alpha.. layers. To further investigate in situ annealing effects, specimens already containing buried ..cap alpha.. layers were further irradiated with ion beams in the temperature range RT-400/sup 0/C. It was found that isolated small ..cap alpha.. zones (less than or equal to 50 diameter) embedded in the crystalline matrix near the two ..cap alpha../c interfaces dissolved into the crystal but the thickness of the 100 percent ..cap alpha.. layer was not appreciably affected by further implantation at 200/sup 0/C. A model for in situ annealing during implantation is presented.
Date: November 1, 1982
Creator: Sadana, D.K.; Washburn, J.; Byrne, P.F. & Cheung, N.W.
Partner: UNT Libraries Government Documents Department

Measurement of the inclusive branching fraction tau/sup -/. -->. nu/sub tau/. pi. /sup -/. pi. /sup 0/ + neutral meson(s)

Description: This dissertation measures an inclusive branching fraction of (13.9 +- 2.0/sub -2.4//sup +2.1/)% for the decay tau/sup -/ ..-->.. nu/sub tau/..pi../sup -/..pi../sup 0/ + nh/sup 0/ where h/sup 0/ is a ..pi../sup 0/ or an eta and n greater than or equal to 1. The data sample, obtained with the TPC detector facility at PEP, corresponds to an integrated luminosity of 72 pb/sup -1/ at 29 GeV center of mass energy. The measured value for this branching fraction is somewhat greater than the theoretical prediction and, taking errors into account, resolves the present difference between the inclusive and the sum of the exclusive tau/sup -/ branching fractions into one charged prong. In addition, a lower limit of 8.3% (95% CL) is placed on the branching fraction B(tau/sup -/ ..-->.. nu/sub tau/..pi../sup -/..pi../sup 0/..pi../sup 0/).
Date: December 1, 1986
Creator: Moses, W.W.
Partner: UNT Libraries Government Documents Department

A low background-rate detector for ions in the 5 to 50 keV energy range to be used for radioisotope dating with a small cyclotron

Description: Accelerator mass spectrometry in tandem Van de Graaff accelerators has proven successful for radioisotope dating small samples. We are developing a 20 cm diameter 30 to 40 keV cyclotron dedicated to high-sensitivity radioisotope dating, initially for /sup 14/C. At this energy, range and dE/dx methods of particle identification are impossible. Thus arises the difficult problem of reliably detecting 30 to 40 keV /sup 14/C at 10/sup -2/ counts/sec in the high background environment of the cyclotron, where lower energy ions, electrons, and photons bombard the detector at much higher rates. We have developed and tested an inexpensive, generally useful ion detector that allows dark-count rates below 10/sup -4/ counts/sec and excellent background suppression. With the cyclotron tuned near the /sup 13/CH background peak, to the frequency for /sup 14/C, the detector suppresses the background to 6 x 10/sup -4/ counts/sec. For each /sup 14/C ion the detectors grazing-incidence Al/sub 2/O/sub 3/ conversion dynode emits about 20 secondary electrons, which are independently multiplied in separate pores of a microchannel plate. The output signal is proportional to the number of secondary electrons, allowing pulse-height discrimination of background. We have successfully tested the detector with positive /sup 12/C, /sup 23/Na, /sup 39/K, /sup 41/K, /sup 85/Rb, /sup 87/Rb, and /sup 133/Cs at 5 to 40 keV, and with 36 keV negative /sup 12/C and /sup 13/CH. It should detect ions and neutrals of all species, at energies above 5 keV, with good efficiency and excellent background discrimination. Counting efficiency and background discrimination improve with higher ion energy. The detector can be operated at least up to 2 x 10/sup -7/ Torr and be repeatedly exposed to air. The maximum rate is 10/sup 6.4/ ions/sec in pulse counting mode and 10/sup 9.7/ ions/sec in current integrating mode.
Date: November 25, 1986
Creator: Friedman, P.G.
Partner: UNT Libraries Government Documents Department

The Lamb shift in heliumlike uranium (U/sup 90 +/)

Description: An experimental value of 70.4 (8.3) eV for the one-electron Lamb shift in uranium is reported, in agreement with the theoretical value of 75.3 (0.4) eV. The Lamb shift is extracted from a beam-foil time-of-flight measurement of the 54.4 (3.4) ps lifetime of the 1s 2p/sub 1/2/ /sup 3/P/sub 0/ state of heliumlike (two-electron) uranium. 18 figs.
Date: January 1, 1987
Creator: Munger, C.T. Jr.
Partner: UNT Libraries Government Documents Department

Near threshold studies of photoelectron satellites

Description: Photoelectron spectroscopy and synchrotron radiation have been used to study correlation effects in the rare gases: He, Ne, Ar, Kr, and Xe. Two kinds of time-of-flight electron analyzers were employed to examine photoionization very close to threshold and at higher kinetic energies. Partial cross sections and angular distributions have been measured for a number of photoelectron satellites. The shake-off probability has been determined at some inner-shell resonances. 121 refs., 28 figs., 13 tabs.
Date: November 1, 1986
Creator: Heimann, P.A.
Partner: UNT Libraries Government Documents Department

Photochemistry and kinetics of gas phase reactions involving HO and Cl radicals

Description: The kinetics of the reaction of the HO radical with HNO/sub 3/ and H/sub 2/O/sub 2/, the kinetics of Cl atom reactions with ClNO and ClNO/sub 2/, and the photochemistry of ClNO/sub 2/ and ClONO/sub 2/ were examined. The ultraviolet absorption cross sections of HNO/sub 3/ and ClNO/sub 2/ were also determined as part of the kinetics work. The rate constant for the reaction of HO with HNO/sub 3/ at room temperature was measured to be (8.2 +- 1.8) x 10/sup -14/ cm/sup 3/ molecule/sup -1/ s/sup -1/, where the uncertainty reported here and in all cases reflects twice the experimental standard deviation plus an estimate of systematic errors. The rate constant for the reaction HO + H/sub 2/O/sub 2/ was measured as (1.57 +- 0.23) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/. This agrees well with the two latest determinations and serves as a calibration of the experimental apparatus used. The Cl + ClNO reaction rate constant was determined to be (1.65 +- 0.32) x 10/sup -11/ cm/sup 3/ molecule/sup -1/ s/sup -1/. The rate constant for the reaction of Cl + ClNO/sub 2/ was found to be (5.05 +- 0.75) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/. This is the first direct measurement of this rate constant. The photodissociation of ClNO/sub 2/ was studied in great detail. The absorption cross sections were measured in the ultraviolet and found to be substantially lower than the literature values in the Cl/sub 2/ absorption region (300 to 360 nm). Two product channels were investigated; products representative of the two channels were Cl and O atoms. Absolute calibration for the product detection systems was provided by Cl/sub 2/ and NO/sub 2/ photolysis respectively. The quantum uields measured for photolysis at 350 nm, calcualted using the absorption spectrum measured ...
Date: November 1, 1980
Creator: Nelson, H.H.
Partner: UNT Libraries Government Documents Department

Possible deviations from (V-A) charged currents: precise measurement of muon decay parameters

Description: This short review examines the experimental limits on possible deviations from (V-A) charged weak currents, as would occur at some mass scale, for example, in manifestly left-right-symmetric electro-weak theories. Both present and anticipated limits are considered, emphasizing muon-decay experiments but including other experimental input where convenient.
Date: February 1, 1981
Creator: Strovink, M.
Partner: UNT Libraries Government Documents Department

Effects of the accident at Three Mile Island on the mental health and behavioral responses of the general population and nuclear workers

Description: On March 28, 1979, an accident occurred at the Three Mile Island nuclear power plant Unit No. 2 near Middletown, PA. A Presidential Commission was established to investigate the incident and was given the responsibility to evaluate the actual and potential impact of the events on the health and safety of the workers and the public. A main conclusion of the investigation was that the most serious health effect was severe, short-lived mental stress. This paper describes the study and the findings for four different study groups: (1) the general population of heads of households located within 20 miles of the plant; (2) mothers of preschool children from the same area; (3) teenagers in the 7th, 9th, and 11th grades from the area; and (4) nuclear workers employed at the Three Mile Island nuclear power plant. (ACR)
Date: February 1, 1983
Creator: Fabrikant, J.I.
Partner: UNT Libraries Government Documents Department

Photoelectron photoion molecular beam spectroscopy

Description: The use of supersonic molecular beams in photoionization mass spectroscopy and photoelectron spectroscopy to assist in the understanding of photoexcitation in the vacuum ultraviolet is described. Rotational relaxation and condensation due to supersonic expansion were shown to offer new possibilities for molecular photoionization studies. Molecular beam photoionization mass spectroscopy has been extended above 21 eV photon energy by the use of Stanford Synchrotron Radiation Laboratory (SSRL) facilities. Design considerations are discussed that have advanced the state-of-the-art in high resolution vuv photoelectron spectroscopy. To extend gas-phase studies to 160 eV photon energy, a windowless vuv-xuv beam line design is proposed.
Date: December 1, 1980
Creator: Trevor, D.J.
Partner: UNT Libraries Government Documents Department

Analytical and numerical models for estimating the effect of exhaust ventilation on radon entry in houses with basements or crawl spaces

Description: Mechanical exhaust ventilation systems are being installed in newer, energy-efficient houses and their operation can increase the indoor-outdoor pressure differences that drive soil gas and thus radon entry. This thesis presents simplified models for estimating the pressure driven flow of radon into houses with basements or crawl spaces, due to underpressures induced by indoor-outdoor temperature differences, wind, or exhaust ventilation. A two-dimensional finite difference model is presented and used to calculate the pressure field and soil gas flow rate into a basement situated in soil of uniform permeability. A simplified analytical model is compared to the finite difference model with generally very good agreement. Another simplified model is presented for houses with a crawl space. Literature on radon research is also reviewed to show why pressure driven flow of soil gas is considered to be the major source of radon entry in houses with higher-than-average indoor radon concentrations. Comparisons of measured vs. calculated indoor radon concentrations for a house with a basement showed the simplified basement model underpredicting on average by 25%. For a house with a crawl space the simplified crawl space model overpredicted by 23% when the crawl space vents are open and 48% when the crawl space vents are sealed.
Date: August 1, 1986
Creator: Mowris, R.J.
Partner: UNT Libraries Government Documents Department

Semiannual report

Description: To understand the dynamics of trace metals in desert environments requires estimates of compartment concentrations or storages (i.e., amounts of elements in soils, plants and animals), determinations of rates of flow between compartments, and estimates of rates at which materials are introduced into and irreversibly lost from the system. This report deals with measurements of amounts of trace elements in the environment surrounding Southern California Edison's Mohave Generating Station in southern Nevada, a collaborative study with Los Alamos Scientific Laboratory of trace elements in the vicinity of the Four Corners Power Plant in New Mexico, and laboratory and field experiments related to cycling of trace elements.
Date: January 1, 1977
Creator: Strojan, C.L.
Partner: UNT Libraries Government Documents Department

Studies of micromorphology and current efficiency of zinc electrodeposited from flowing chloride electrolytes

Description: Results of a study of the micromorphology and current efficiency of zinc electrodeposited from flowing, acidic chloride solutions are reported. The effects of six variables were examined: flow rate, current density, zinc and hydrogen ion concentration, concentrations of nickel, iron and cadmium impurity ions, and the nature of the substrate. The development of micromorphology was studied in-situ by means of videomicrography and ex-situ by means of scanning electron microscopy. This investigation focused on the formation of grooved deposits, which are found under a wide range of deposition conditions. The major conclusions of this study are: the most important variable determining whether grooved deposits form is the interfacial concentration; large protrusions orient themselves parallel to the flow direction with the orientation starting upstream and progressing downstream; large protrusions become ridges due to growth of the highest current density portions of the electrode under mass transport control. The current efficiency was measured using EDTA titration and weight measurements. The fraction of the current taken by zinc deposition increased with zinc concentration, ranging up to 100%, and decreased with pH. The efficiency of zinc deposition was affected by the flow rate and the substrate employed. Impurities lowered the current efficiency.
Date: May 1, 1986
Creator: Mc Vay, L.; Muller, R.H. & Tobias, C.W.
Partner: UNT Libraries Government Documents Department

Land use and environmental impacts of decentralized solar energy use

Description: The physical, spatial and land-use impacts of decentralized solar technologies applied at the community level by the year 2000 are examined. The results of the study are intended to provide a basis for evaluating the way in which a shift toward reliance on decentralized energy technologies may eventually alter community form. Six land-use types representative of those found in most US cities are analyzed according to solar penetration levels identified in the maximum solar scenario for the year 2000. The scenario is translated into shares of end use demand in the residential, commercial and industrial sectors. These proportions become the scenario goals to be met by the use of decentralized solar energy systems. The percentage of total energy demand is assumed to be 36.5 percent, 18.8 percent and 22.6 percent in the residential, commercial and industrial sectors respectively. The community level scenario stipulated that a certain percentage of the total demand be met by on-site solar collection, i.e. photovoltaic and thermal collectors, and by passive design. This on-site solar goal is 31.9 percent (residential), 16.8 percent (commercial) and 13.1 percent (industrial).
Date: January 1, 1980
Creator: Twiss, R.H.; Smith, P.L.; Gatzke, A.E. & McCreary, S.T.
Partner: UNT Libraries Government Documents Department