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Influence of compositional modifications on the corrosion of iron aluminides of molten nitrate salts
The corrosion of iron-aluminum alloys by molten nitrate salt as a function of aluminum, chromium, and other minor elements has been studied as part of an alloy design effort aimed at the development of a strong, ductile, corrosion-resistant FeAl type of aluminide. Short- term weight change data were used to examine the compositional dependence of the corrosion processes that occurred upon exposure of iron aluminides to highly oxidizing nitrate salts of 650{degrees}C. Corrosion resistance was found to increase with increasing aluminum concentrations of the alloy up to approximately 30 at. % Al. Chromium additions to the aluminide were not detrimental and may have improved the corrosion behavior for certain aluminum concentrations. No effects of minor alloying additions (C, B, Ti, and Zr) could be determined. The best overall corrosion resistance as measured by weight change results were obtained for an Fe-35.8 at. % Al aluminide containing some chromium. Based on linear weight loss kinetics, the weight change measurements for the most resistant compositions predict corrosion rates of 300 {mu}m/year or less at 650{degrees}C. These rates are substantially better than typical nickel-based alloys and stainless steels. From a consideration of the weight changes; the microstructural, thermodynamic, and X-ray diffraction data; and …
Date:
January 1, 1991
Creator:
Tortorelli, P. F. & Bishop, P. S.
Object Type:
Report
System:
The UNT Digital Library
Two-photon couplings of quarkonia with arbitrary angular momenta
The observation of a large {gamma}{gamma} width for the {sup 1}D{sub 2} q{bar q} state {pi}{sub 2}(1670) suggests that the {gamma}{gamma} couplings of many orbitally-excited light q{bar q} states may be experimentally accessible. In this talk we present {gamma}{gamma} helicity amplitudes for q{bar q} states with general angular momenta {sup 1}l{sub j} and {sup 3}l{sub j}, and note some relations and selection rules that may be useful in spectroscopic classification of orbital excitations. 14 refs.
Date:
January 1, 1991
Creator:
Barnes, T. (Oak Ridge National Lab., TN (United States) Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy)
Object Type:
Article
System:
The UNT Digital Library
(Theoretical studies in elementary particle physics)
This report discusses research in: spin physics; transverse polarization and jet production; fundamental QCD; intermediate vector boson production; and hadron collisions. (LSP)
Date:
January 1, 1991
Creator:
Collins, J.
Object Type:
Report
System:
The UNT Digital Library
Error Analysis of Acceleration Control Loops of a Synchrotron
For beam control during acceleration, it is conventional to derive the frequency from an external reference, be it a field marker or an external oscillator, to provide phase and radius feedback loops to ensure the phase stability, radial position and emittance integrity of the beam. The open and closed loop behaviors of both feedback control and their response under the possible frequency, phase and radius errors are derived from fundamental principles and equations. The stability of the loops is investigated under a wide range of variations of the gain and time delays. Actual system performance of the AGS Booster is analyzed and compared to commissioning experiences. Such analysis is useful for setting design criteria and tolerances for new proton synchrotrons. 4 refs., 13 figs.
Date:
January 1, 1991
Creator:
Zhang, S. Y. & Weng, W. T.
Object Type:
Article
System:
The UNT Digital Library
Research on oil recovery mechanisms in heavy oil reservoirs
The goal of the Stanford University Petroleum Research Institute is to conduct research directed toward increasing the recovery of heavy oils. Presently, SUPRI is working in five main directions: To assess the influence of different reservoir conditions (temperature and pressure) on the absolute and relative permeability to oil and water and on capillary pressure; To evaluate the effect of different reservoir parameters on the in-situ combustion process. This project includes the study of the kinetics of the reactions; To develop and understand the mechanisms of the process using commercially available surfactants for reduction of gravity override and channeling of steam; To develop and improve techniques of formation evaluation such as tracer tests and pressure transient tests; and To provide technical support for design and monitoring of DOE sponsored or industry initiated field projects.
Date:
January 1, 1991
Creator:
Brigham, W.E.; Aziz, K. & Ramey, H.J. Jr.
Object Type:
Report
System:
The UNT Digital Library
Solder fatigue reduction in point focus photovoltaic concentrator modules
Solder fatigue tests have been conducted on point focus photovoltaic concentration cell assemblies to identify a baseline fatigue life and to quantify the fatigue life improvements that result using a copper-molybdenum-copper low-expansion insert between the solar cell and copper heat spreader. Solder microstructural changes and fatigue crack growth were identified using cross sections and ultrasonic scans of the fatigue solder joints. The Coffin-Manson and Total Strain fatigue models for low-cycle fatigue were evaluated for use in fatigue life predictions. Since both of these models require strain calculations, two strain calculation methods were compared: hand-calculated shear strain and a finite element method shear strain. At present, the available theoretical models for low-cycle solder fatigue are limited in their ability to predict failure; consequently, extensive thermal cycling is continuing to define the fatigue life for point focus photovoltaic cell assemblies. 9 refs., 9 figs., 2 tabs.
Date:
January 1, 1991
Creator:
Hund, T. D. & Burchett, S. N.
Object Type:
Article
System:
The UNT Digital Library
An overview of acoustic telemetry
Acoustic telemetry has been a dream of the drilling industry for the past 50 years. It offers the promise of data rates which are one-hundred times greater than existing technology. Such a system would open the door to true logging-while-drilling technology and bring enormous profits to its developers. The basic idea is to produce an encoded sound wave at the bottom of the well, let it propagate up the steel drillpipe, and extract the data from the signal at the surface. Unfortunately, substantial difficulties arise. The first difficult problem is to produce the sound wave. Since the most promising transmission wavelengths are about 20 feet, normal transducer efficiencies are quire low. Compounding this problem is the structural complexity of the bottomhole assembly and drillstring. For example, the acoustic impedance of the drillstring changes every 30 feet and produces an unusual scattering pattern in the acoustic transmission. This scattering pattern causes distortion of the signal and is often confused with signal attenuation. These problems are not intractable. Recent work has demonstrated that broad frequency bands exist which are capable of transmitting data at rates up to 100 bits per second. Our work has also identified the mechanism which is responsible for …
Date:
January 1, 1992
Creator:
Drumheller, D. S.
Object Type:
Article
System:
The UNT Digital Library
Fermi molecular dynamics
classical many body models supplemented by repulsive momentum-dependent potentials to simulate the Pauli and Heisenberg principles have been use with some success for nuclear and atomic bound state and collision problems. They are capable of describing mean ground state properties, hydrodynamics, shocks (if warranted by the physics), viscosity, correlations, clustering, fragmentation, etc. We have become interested in the Feldmeier Gaussian packet formulation since it is based on a variational principle using trial wave functions. We discuss some limitations of the model and discuss further directions of investigation.
Date:
January 1, 1991
Creator:
Wilets, L. & Beck, W.
Object Type:
Article
System:
The UNT Digital Library
Object-oriented data handling system for an automated chemistry laboratory
The environmental-remediation efforts at DOE complexes require characterizing problems at each site before cleanup action. Characterization will require the chemical analysis of millions of samples at a significant cost. Automation of the required chemical analyses methods provides a cost-effective solution. An object-oriented approach was deemed necessary to allow for modularization, maintainability, reusability, and flexibility of the software and hardware. Each chemical analysis method is implemented as a Standard Analysis Method or SAM. A SAM is, in essence, a black box'' into which a sample enters at one end and chemical or physical information exits'' at the other. 7 refs., 6 figs.
Date:
January 1, 1991
Creator:
Medvick, P.A.; Mniszewski, S.M. & Beugelsdijk, T.J.
Object Type:
Article
System:
The UNT Digital Library
Nonlinear optical properties of new KTiOPO sub 4 isostructures
The atomic structures of the nonlinear optical materials potassium titanyl phosphate (KTiOPO{sub 4}, or KTP) and potassium titanyl arsenate (KTiOAsO{sub 4}) feature one-dimensional channels through which the potassium ions are relatively free to migrate. Ion exchange results when these materials are immersed in molten salts containing alkali metal ions. Sodium, lithium and silver all exchange readily for K{sup +} single crystals of both KTP and KTA to yield the exchanged derivatives Na{sub .95}K{sub .05}TiOPO{sub 4} (NaTP), Na{sub .83}K{sub .17}TiOAsO{sub 4} (NaTA), Ag{sub .85}K{sub .15}TiOPO{sub 4} (AgTP), Ag{sub .98}K{sub .02}TiOAsO{sub 4} (AgTA), Li{sub .45}K{sub .55}TiOPO{sub 4} (KLTP), and Li{sub .46}K{sub .54}TiOAsO{sub 4} (KLTA), which are all KTP isostructures. The optical nonlinearities (measured as SHG intensities) of the limiting compositions in the NaTA, KLTP, and KLTA systems are similar to that of KTP, but are much smaller in NaTP, AgTP and AgTA. Single crystal X-ray data have revealed differences in coordination of the mobile cations to oxygen atoms linking the TiO{sub 6} groups in these compounds, and these differences correlate with changes in optical nonlinearity. The observed nonlinearities can be rationalized if they are viewed as being dependent on the degree to which delocalized charge-transfer excited state character can be mixed into …
Date:
January 1, 1991
Creator:
Phillips, M. L. F.; Harrison, W. T. A. & Stucky, G. D.
Object Type:
Article
System:
The UNT Digital Library
Graphic values for some organic constitutents of beneficiated coal samples
Graphic techniques exist which can accurately predict values for calorific value, organic sulfur, and possibly other constituents of the organic portion of beneficiated coal sample fractions. These techniques also permit a determination of coal rank to be made without the use of the approximations required in the standard procedure. Fractions of IBC-101 with varying ash contents were produced by froth flotation. The various fractions were analyzed by the coal analysis laboratory and the particular data type was plotted in each case vs. the individual ash content of each fraction, using Lotus 123 and Freelace software packages. Such plots for calorific value and organic sulfur have, so far, been made. These curves and the information they contain are discussed in this report. A comparison of the graphic mineral matter value with the usual one calculated from the Parr approximation has been made. Eventually, the data may lead to an effective way to estimate inorganic carbon, hydrogen, nitrogen, and other organic constitents of coal. All data will be made available to researchers.
Date:
January 1, 1992
Creator:
Kohlenberger, L. B.
Object Type:
Report
System:
The UNT Digital Library
(Technical and engineering support for the Office of Industrial Programs)
As of April 19, 1991, technical, operational and analytic support and assistance to the offices and divisions of the Office of Renewable Energy, under contract DE-AC01-86CE30844 was completed. The overall work effort, initiated February 20, 1986, was characterized by timely, comprehensive, high quality, professional responsiveness to a broad range of renewable energy program operational support requirements. These are no instances of failure to respond, nor unacceptable response, during the five-year period. The technology program areas covered are Solar Buildings Technology, Wind Energy Technology, Photovoltaic Energy Technology, Geothermal Energy Technology, Biofuels and Municipal Waste Technology, Solar Thermal Technology, Hydropower Energy Technology, Ocean Energy Technology, and Electric Energy Systems and Energy Storage. The analytical and managerial support provided to the office and staff of the Deputy Assistant Secretary for Renewable Energy enabled a comprehensive evaluation of program and policy alternatives, and the selection and execution of appropriate courses of action from amongst those alternatives. Largely through these means the Office has been able to maintain continuity and a meaningful program thrust through the vacillations of policies and budgets that it has experienced over that it has experienced over the past five years. Appended are summaries of support activities within each of the …
Date:
January 1, 1991
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Superconductivity: Past, present, and future
This paper provides an overview of superconductor research and development activities, with emphasis on the potential of high-{Tc} materials for future applications. Superconductor applications are grouped under the following categories: electronics/instrumentation, bulk material/castings, research devices, industrial/commercial, electric power, and transportation/propulsion. Near-term applications are typically based on thin film and cast forms of high-{Tc} materials, while large-scale applications requiring long lengths of wire are considered intermediate to long term. As a major side benefit of high-{Tc} superconductor research, renewed interest is being focused on the use of low-{Tc} materials for large-scale applications.
Date:
January 1, 1992
Creator:
Uherka, K.L.
Object Type:
Article
System:
The UNT Digital Library
Edge-on ion irradiation of electron microscope specimens
A special technique is described for in situ transmission electron microscope (TEM) experiments involving simultaneous ion irradiation, in which the resultant phenomena are observed as in a cross-section TEM specimen. That is, instead of ion-irradiating the film or foil specimen normal to the major surfaces and observing in plan view (i.e., in the same direction), the specimen is irradiated edge-on (i.e., parallel to the major surfaces) and is observed normal to the depth direction with respect to the irradiation. The results of amorphization of Si, irradiated in this orientation by 1 or 1.5 MeV Kr, are presented and briefly compared with the usual plan view observations. The limitations of the technique are discussed and several experiments which might profitably employ this technique are suggested.
Date:
January 1, 1992
Creator:
Otero, M. P. & Allen, C. W.
Object Type:
Article
System:
The UNT Digital Library
Effect of high aspect ratio on ITER maintenance design
The International Thermonuclear Experimental Reactor (ITER) baseline machine configuration and auxiliary systems design specify maintainability and repairability as fundamental requirements. Two important maintenance requirements for ITER are a device that is fully remotely maintainable, with the provision for hands-on maintenance wherever possible, and the ability to maintain components with short lives or high failure rates without moving other components or disturbing the machine's internal or external environment. Some of the maintenance tasks are accomplished through the use of specialized remote maintenance equipment that will perform crucial in-vessel and ex-vessel operations. In-vessel maintenance will be performed with a combination of horizontal and vertical access. Since the completion of the Conceptual Design Activity (CDA), systems studies by the US ITER design team have pointed to the possible benefits of a high aspect ratio design (HARD). The alternative HARD has been shown to have better performance characteristics than the present baseline. The HARD machine configuration modified in size a number of major components that must be remotely maintained or replaced. This required reevaluation of the maintenance scenarios of these components with respect to changes in physical accessibility, assembly and disassembly, and remote maintenance equipment. The CDA baseline design and HARD are compared from …
Date:
January 1, 1991
Creator:
Herrick, T.J.; Davis, F.C.; Hollis, M.J. & Lousteau, D.C.
Object Type:
Article
System:
The UNT Digital Library
ADIFOR: Automatic differentiation in a source translator environment
The numerical methods employed in the solution of many scientific computing problems require the computation of derivatives of a function f: R{sup n} {yields} R{sup m}. ADIFOR (Automatic Differentiation in FORtran) is a source transformation tool that accepts Fortran 77 code for the computation of a function and writes portable Fortran 77 code for the computation of the derivatives. In contrast to previous approaches, ADIFOR views automatic differentiation as a source transformation problem and employs the data analysis capabilities of the ParaScope Fortran programming environment. Experimental results show that ADIFOR can handle real- life codes and that ADIFOR-generated codes are competitive with divided-difference approximations of derivatives. In addition, studies suggest that the source-transformation approach to automatic differentation may improve the time required to compute derivatives by orders of magnitude.
Date:
January 1, 1992
Creator:
Bischof, C.; Corliss, G.; Griewank, A. (Argonne National Lab., IL (United States)) & Carle, A. (Rice Univ., Houston, TX (United States). Center for Research on Parallel Computation)
Object Type:
Article
System:
The UNT Digital Library
Direct conversion of light hydrocarbon gases to liquid fuel
The objective of this program is to investigate the direct conversion of light gaseous hydrocarbons, such as those produced during Fischer-Tropsch synthesis or as a product of gasification, to liquid transportation fuels via a partial oxidation process. The process will be tested in an existing pilot plant to obtain credible mass balances. Specific objectives to be met include determination of optimal process conditions, investigation of various processing options (e.g. feed injection, product quench, and recycle systems), and evaluation of an enhanced yield thermal/catalytic system. Economic evaluation of the various options will be performed as experimental data become available.
Date:
January 1, 1991
Creator:
Foral, M.J.
Object Type:
Report
System:
The UNT Digital Library
The product consistency test for the DWPF wasteform
The preliminary specifications on the glass wasteform to be produced by the Defense Waste Processing Facility (DWPF) require extensive characterization of the glass product both before actual production begins and then during production. To aid in this characterization, a leach test was needed that was easily reproducible, could be performed remotely on highly radioactive samples, and could yield results rapidly. Several standard leach tests were examined with a variety of test configurations. Using existing tests as a starting point, the DWPF Product Consistency Test (PCT) was developed in which crushed glass samples are exposed to 90{degrees}C deionized water for seven days. Based on extensive testing, including a seven-laboratory round robin and confirmatory testing with radioactive samples, the PCT is very reproducible, yields reliable results rapidly, and can be performed in shielded cell facilities with radioactive samples.
Date:
January 1, 1990
Creator:
Jantzen, Carol M. & Bibler, N. E.
Object Type:
Article
System:
The UNT Digital Library
Atomic structure of clusters through chemical reactions
Techniques for the probing of isolated metal cluster structure through adsorbate binding patterns will be described. The saturation of clusters with reagents such as ammonia and nitrogen provides information on the number of preferred binding sites for these reagents. The dependence of this number on cluster size can suggest particular structural themes. The equilibrium reaction with water can be used to identify cluster sizes having especially enhanced binding for the water molecule. Again, the sequence of cluster sizes showing such enhancement can point to specific cluster structure. The reaction with oxygen can identify cluster sizes having particularly high ionization potentials, and these can be compared to simple models for the electronic structure of metal clusters. Representative applications of these probes to iron, cobalt, nickel, and copper clusters will be discussed. 5 figs.
Date:
January 1, 1991
Creator:
Riley, S.J.
Object Type:
Article
System:
The UNT Digital Library
Analysis of erosion and transport of carbon impurity in the TFTR inner bumper limiter region
Carbon sputtering and transport on the TFTR inner graphite bumper limiter is investigated with the impurity transport code REDEP. Analysis is carried out for a series of ohmic discharges in TFTR. Predictions for Z{sub eff} in the core plasma agree well with in-situ experimental measurements. Run-away self-sputtering of carbon is predicted at low densities and high edge plasma temperatures when the limiter surface was purged of deuterium. Surface erosion and deposition is analyzed. In general, redeposition reduces the peak erosion by about a factor of five. Analysis is also carried out for a typical neutral beam heated discharge with a noncircular plasma. Spatial surface erosion and deposition profiles are compared qualitatively with beta backscattering measurements of metal deposition found on the limiter.
Date:
January 1, 1992
Creator:
Hua, T. Q. & Brooks, J. N.
Object Type:
Article
System:
The UNT Digital Library
The electronics and data acquisition system for the Wire Imaging Synchrotron Radiation Detector at the SLC (Stanford Linear Collider)
The Stanford Linear Collider (SLC) located at the Stanford Linear Accelerator Center collides electrons and positrons produced in the linear accelerator pulse by pulse. We determine the energy of each beam by measuring the angle of deflection of the beam in the SLC extraction lines. Each extraction line consists of two bending magnets that produce synchrotron radiation, and a spectrometer analyzing magnet that deflects the beam. We detect the synchrotron light by using the emission of electrons produced by Compton scattering off Cu-Be wires. We detect the {approximately} 180 fC of charge on the wire by using the electronics system described in this paper. We also discuss the performance of the system, including the equivalent noise charge, cross-talk between channels, stability, and reliability. 4 refs., 7 figs.
Date:
January 1, 1990
Creator:
Rouse, F.; Briggs, D.D. (Stanford Linear Accelerator Center, Menlo Park, CA (USA)); Gomez, J.J.; Von Zanthier, C. & Kent, J. (California Univ., Santa Cruz, CA (USA))
Object Type:
Article
System:
The UNT Digital Library
The Fresh-Bunch' technique in FELs
The 'Fresh Bunch' technique is being proposed as a method of increasing the gain and power of FEL amplifiers in which the length of the optical radiation pulse is shorter than the length of the electron bunch. In multi-stage FEL, electron beam energy spread is increased by the FEL interaction in the early stages. In the 'Fresh Bunch' technique, the low energy spread of the electron beam is recovered by shifting the radiation pulse to an undisturbed part of the electron bunch, thus improving the gain and trapping fraction in later stages. A test case for the application of the Fresh Bunch method is demonstrated by numerical simulation. In this particular example we examine a subharmonically seeded VUV Free-Electron Laser. We begin with the generation of harmonic radiation, which takes place over one part of the electron bunch. Then the radiation is shifted by means of a strong dispersive section to a fresh part of the bunch for exponential amplification and tapered wiggler amplification. By starting over with a new ensemble of electrons, the energy spread introduced by the bunching in the fundamental is removed, leading to an increased gain. Furthermore, it is possible to use a much stronger seed …
Date:
January 1, 1991
Creator:
Ben-Zvi, Ilan; Yang, K. M. & Yu, L. H.
Object Type:
Article
System:
The UNT Digital Library
Visual tools and languages: Directions for the '90s
We identify and discuss three domains where we believe that innovative application of visual programming languages is likely to make a significant impact in the near term: concurrent computing, computer-based assistance for people with disabilities, and the multimedia/multimodal environments of tomorrow in which it will be possible to hear and physically interact with information as well as see it. 33 refs., 3 figs.
Date:
January 1, 1991
Creator:
Glinert, E.P. (Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Computer Science); Blattner, M.M. (Lawrence Livermore National Lab., CA (United States)) & Frerking, C.J. (California Univ., Davis, CA (United States))
Object Type:
Article
System:
The UNT Digital Library
An optimized algorithm for solving the nodal diffusion method on shared memory multiprocessors
Nodal methods play a special role in reactor physics calculations. In recent papers the high computational efficiency of nodal methods has been established and the development of more efficient algorithms tailored to the advanced architectures of modern day computers proposed. The rapidly changing architectures of today's computer influence the way codes have to be programmed so that reasonable speed up and efficiency are attained. We have applied these concepts in solving the one-group neutron diffusion equation in two-dimensional geometry on parallel computers like the Intel iPSC/2 hypercube and the Sequent Balance 8000. The efficiency of the hypercube for the neutron diffusion equation is highly determined by the message passing scheme; on the other hand, on a shared memory processor like the Sequent, it is dependent on the manipulation of variables in shared memory. In this paper, we present a scheme on shared memory processors which produces very high computing efficiencies in agreement with Amdahl's law. 6 refs., 1 fig.
Date:
January 1, 1990
Creator:
Kirk, B.L. & Azmy, Y.Y.
Object Type:
Article
System:
The UNT Digital Library