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Dislocation accumulation at large plastic strains -- An approach to the theoretical strength of materials

Description: The usual method of introducing engineers to the concept of dislocations and their role in plastic flow is to compare an estimate of the theoretical strength of solid (of order {micro}/30 where {micro} is the shear modulus) and the observed strength of either single crystals ({mu}/10{sup 4}) or practical engineering material such as structural steels where the yield stress in shear is of order {mu}/10{sup 3}. However, if one considers the problem in reverse, one can consider the accumulation of dislocations as an important mechanism by which one can produce engineering materials in which the strength level approaches the theoretical strength. If one assumes that the flow stress can be expressed in terms of te mean free path between stored dislocations or as the square root of the global dislocation density, then one can see the influence of dislocation density in a diagrammatic form. It is clear that the strengthening by dislocation accumulation due to large imposed plastic strains represents an important approach both to the development of new, potentially valuable, engineering materials and an important area of basic understanding in terms of the mechanical response of materials close to their theoretical strength. Thus, this article will survey some of the factors which influence dislocation accumulation at large strains and the consequences of such accumulation processes.
Date: April 1, 1999
Creator: Embury, J.D. & Han, K.
Partner: UNT Libraries Government Documents Department

First principles total energy study of NbCr{sub 2} + V Laves phase ternary system

Description: The C15 NbCr{sub 2} + V Laves phase ternary system is studied by using a first-principles, self-consistent, full-potential total energy method. Equilibrium lattice parameters, cohesive energies, density of states and formation energies of substitutional defects are calculated. Results of all these calculations show that in the C15 NbCr{sub 2} + V compounds, V atoms substitute Cr atoms only.
Date: April 1, 1999
Creator: Ormeci, A.; Chen, S.P.; Wills, J.M. & Albers, R.C.
Partner: UNT Libraries Government Documents Department

An explicit model of expanding cylindrical shells subjected to high explosive detonations

Description: A viscoplastic constitutive model was formulated to model the high strain-rate expansion of thin cylindrical shells subjected to internal explosive detonations. This model provides insight into the development of plastic instabilities, which occur on the surface of the shells prior to failure. The effects of shock heating and damage in the form of microvoid nucleation, growth, and coalescence were incorporated using the Johnson-Cook strength model with the Mie-Grueneisen equation of state and a modified Gurson yield surface. This model was implemented into ABAQUS/Explicit as a user material subroutine. A cylindrical copper shell was modeled using both axisymmetric and plane strain elements. The high explosive material inside of the cylinder was simulated using the high explosive burn model in ABAQUS/Explicit. Two experiments were conducted involving explosive-filled, copper cylinders and good agreement was obtained between the numerical results and experimental data.
Date: April 1, 1999
Creator: Martineau, R.L.; Prime, M.B.; Anderson, C.A. & Smith, F.W.
Partner: UNT Libraries Government Documents Department

Simulated effects of climate change on the Death Valley regional ground-water flow system, Nevada and California

Description: The US Geological Survey, in cooperation with the US Department of Energy, is evaluating the geologic and hydrologic characteristics of the Death Valley regional flow system as part of the Yucca Mountain Project. As part of the hydrologic investigation, regional, three-dimensional conceptual and numerical ground-water-flow models have been developed to assess the potential effects of past and future climates on the regional flow system. A simulation that is based on climatic conditions 21,000 years ago was evaluated by comparing the simulated results to observation of paleodischarge sites. Following acceptable simulation of a past climate, a possible future ground-water-flow system, with climatic conditions that represent a doubling of atmospheric carbon dioxide, was simulated. The steady-state simulations were based on the present-day, steady-state, regional ground-water-flow model. The finite-difference model consisted of 163 rows, 153 columns, and 3 layers and was simulated using MODFLOWP. Climate changes were implemented in the regional ground-water-flow model by changing the distribution of ground-water recharge. Global-scale, average-annual, simulated precipitation for both past- and future-climate conditions developed elsewhere were resampled to the model-grid resolution. A polynomial function that represents the Maxey-Eakin method for estimating recharge from precipitation was used to develop recharge distributions for simulation.
Date: April 1, 1999
Creator: D`Agnese, Frank A.; O`Brien, Grady M.; Faunt, Claudia C. & San Juan, Carma A.
Partner: UNT Libraries Government Documents Department

Petroleum marketing monthly, April 1999, with data for January 1999

Description: The Petroleum Marketing Monthly (PMM) provides information and statistical data on a variety of crude oils and refined petroleum products. The publication presents statistics on crude oil costs and refined petroleum products sales for use by industry, government, private sector analysts, educational institutions, and consumers. Data on crude oil include the domestic first purchase price, the f.o.b. and landed cost of imported crude oil, and the refiners` acquisition cost of crude oil. Refined petroleum product sales data include motor gasoline, distillates, residuals, aviation fuels, kerosene, and propane. The Petroleum Marketing Division, Office of Oil and Gas, Energy Information Administration ensures the accuracy, quality, and confidentiality of the published data in the Petroleum Marketing Monthly. 56 tabs.
Date: April 1, 1999
Partner: UNT Libraries Government Documents Department

Laboratory Evaluation of In Situ Chemical Oxidation for Groundwater Remediation, Test Area North, Operable Unit 1-07B, Idaho National Engineering and Environmental Laboratory, Volume One - Main Text and Appendices A and B

Description: The laboratory investigation was performed to evaluate the feasibility of utilizing in situ chemical oxidation for remediating the secondary source of groundwater contaminants at the Idaho National Engineering and Environmental Laboratory (INEEL) Test Area North (TAN) Site. The study involved trichloroethene (TCE) contaminated media (groundwater, soil, and sludge) from TAN. The effectiveness of the selected oxidant, potassium permanganate (KMn0(sub4)), was evaluated at multiple oxidant and contaminant concentrations. Experiments were performed to determine the oxidant demand of each medium and the rate of TCE oxidation. The experiments were performed under highly controlled conditions (gas-tight reactors, constant 12C temperature). Multiple parameter were monitored over time including MN0(sub 4) and TCE concentrations and pH.
Date: April 1, 1999
Creator: Cline, S.R.; Denton, D.L.; Giaquinto, J.M.; McCracken, M.K. & Starr, R.C.
Partner: UNT Libraries Government Documents Department

One-Angstrom microscope update

Description: The One-Angstrom Microscope project has attained its goal, and is now producing images down to 1 Angstrom resolution. We have demonstrated transmission electron microscopy of defect structures down to a resolution of 1.1 Angstrom, with evidence that 0.89 Angstrom will be possible. This level of resolution will soon be made available to all those NCEM users who have a requirement for sub-Angstrom resolution.
Date: April 4, 1999
Creator: O'Keefe, Michael A.
Partner: UNT Libraries Government Documents Department

Elastohydrodynamic Lubrication with Polyolester Lubricants and HFC Refrigerants, Final Report, Volume 1

Description: The objective of this study was to investigate the film formation properties of refrigeration lubricants using the ultrathin film elastohydrodynamic (EHD) interferometry technique and to study the effects of refrigerants on film formation. Film thickness measurements were conducted as a function of lubricant viscosity, speed, temperature, and refrigerant concentration. Based on the EHD film thickness data, effective pressure-viscosity coefficients were calculated for the test fluids at different temperatures and the effects of refrigerants on pressure-viscosity properties were investigated.
Date: April 1, 1999
Creator: Gunsel, Selda & Pozebanchuk, Michael
Partner: UNT Libraries Government Documents Department

Laboratory Evaluation of In Situ Chemical Oxidation for Groundwater Remediation, Test Area North, Operable Unit 1-07B, Idaho National Engineering and Environmental Laboratory, Volume Three - Appendix F

Description: This appendix supports the results and discussion of the laboratory work performed to evaluate the feasibility of in situ chemical oxidation for Idaho National Environmental and Engineering Laboratory's (INEEL) Test Area North (TAN) which is contained in ORNL/TM-13711/V1. This volume contains Appendix F. Appendix F is essentially a photocopy of the ORNL researchers' laboratory notebooks from the Environmental Sciences Division (ESD) and the Radioactive Materials Analytical Laboratory (RMAL).
Date: April 1, 1999
Creator: Cline, S.R.; Denton, D.L.; Giaquinto, J.M.; McCracken, M.K. & Starr, R.C.
Partner: UNT Libraries Government Documents Department

Including Internal Losses In The Equivalent Circuit Model Of The SLAC Damped Detuned Structure (DDS)

Description: In the equivalent circuit model for the DDS originally presented no losses were explicitly included in the cell circuits or the manifold circuits. Damping via the manifolds was effected by imposing matching conditions (including the possibility of reflection) on the ends of the manifolds. In this paper we extend the circuit theory to include lossy circuit elements. We discuss and compare shunt conductance and series resistance models for the cells. Manifold damping is modeled by introducing a shunt conductance per unit length in the transmission line elements of the manifolds. We apply the theory to the mitigation of performance degradation associated with fabricationally desirable decoupling of several cells at the ends of the structure from the manifolds.
Date: April 1, 1999
Creator: Jones, Roger M
Partner: UNT Libraries Government Documents Department

The need and options available for permanent CO{sub 2} disposal

Description: Inexpensive, readily available energy is the cornerstone of modern society and the basis of a decent standard of living. The high probability of future restrictions on CO{sub 2} emissions has put in question the use of fossil fuels, the largest, most convenient, and most cost-effective energy resource available. The rapidly growing world population, the need for an improved standard of living worldwide, and the nearly linear dependence of the standard of living on energy consumption, all coupled with the magnitude of today`s CO{sub 2} emissions point to an impending crisis. The authors briefly review the problem and look at the available options. They conclude that for the foreseeable future, fossil fuels will continue to dominate the world energy market, but that CO{sub 2} disposal will be required. Of the possible disposal options, mineral sequestration of CO{sub 2} appears as an extremely promising, permanent, and environmentally benign disposal option.
Date: April 1999
Creator: Ziock, H. J.; Butt, D. P.; Lackner, K. S. & Wendt, C. H.
Partner: UNT Libraries Government Documents Department

Ab initio calculations of As-vacancy interactions in silicon

Description: Atomistic simulation of a vacancy-assisted dopant diffusion in silicon needs details of the dopant-vacancy interaction, i.e., the potential as a functional of dopant-vacancy separations. In this paper, the authors present a detailed study on the energetics of As-vacancy reaction in silicon and the lattice distortions surrounding the As-vacancy defect by using an ab initio plane wave pseudopotential method and the density functional theory (DFT). A potential-energy diagram as a function of As-vacancy separation is provided, which can be used in the atomistic diffusion simulations. The authors also calculate the binding energy and the formation energy of different complexes such as AsV, As{sub 2}V and AsV{sub 2} (V represents vacancy). They find that the stable configuration of As{sub 2}V is As-V-As, while the stable configuration of AsV{sub 2} is As-V-V. The nature of the binding between As and vacancy is explained from the lattice distortions and the change of chemical bond configuration introduced by the As-vacancy complex.
Date: April 1, 1999
Creator: Xie, J. & Chen, S.P.
Partner: UNT Libraries Government Documents Department

Synthesis and properties of erbium oxide single crystals

Description: Erbium oxide (Er{sub 2}O{sub 3}, erbia) is a highly stable cubic rare earth oxide with a high melting point of 2,430 C. Because of this, it may have potential applications where high temperature stability and corrosion resistance are required. However, relatively little is known about the properties of this oxide ceramic. The authors have employed a xenon optical floating zone unit with a temperature capability of 3,000 C to grow high quality single crystals of erbia. The conditions for single crystal growth of erbia have been established. The mechanical properties of erbia single crystals have been initially examined using microhardness indentation as a function of temperature.
Date: April 1, 1999
Creator: Petrovic, J.J.; Romero, R.S.; Mendoza, D.; Kukla, A.M.; Hoover, R.C. & McClellan, K.J.
Partner: UNT Libraries Government Documents Department

Electric power monthly, April 1999 with data for January 1999

Description: The Electric Power Monthly (EPM) presents monthly electricity statistics for a wide audience including Congress, Federal and State agencies, the electric utility industry, and the general public. The purpose of this publication is to provide energy decisionmakers with accurate and timely information that may be used in forming various perspectives on electric issues that lie ahead. The Electric Power Division; Office of Coal, Nuclear, Electric and Alternate Fuels, Energy Information Administration (EIA), Department of Energy prepares the EPM. This publication provides monthly statistics at the State, Census division, and US levels for net generation, fossil fuel consumption and stocks, quantity and quality of fossil fuels, cost of fossil fuels, electricity retail sales, associated revenue, and average revenue per kilowatthour of electricity sold. In addition, data on net generation, fuel consumption, fuel stocks, quantity and cost of fossil fuels are also displayed for the North American Electric Reliability Council (NERC) regions. The EIA publishes statistics in the EPM on net generation by energy source; consumption, stocks, quantity, quality, and cost of fossil fuels; and capability of new generating units by company and plant.
Date: April 1, 1999
Partner: UNT Libraries Government Documents Department

Annual report to Congress, 1998

Description: Section 205 of the Department of Energy Organization Act of 1977 established the Energy Information Administration (EIA). One of the mandates in this legislation is that EIA prepare for Congress an annual report summarizing both activities and information collected and published. EIA`s major 1998 accomplishments are profiled in the body of this edition of the Annual Report to Congress. Appendix A contains abstracts of significant reports issued by EIA in 1998 and a chart of all titles and a list of all feature articles published during the year. Appendix B contains graphs of selected performance measures. Appendix C lists contact information for EIA subject matter specialists. Appendix D lists the major laws which form the basis of EIA`s legislative mandate.
Date: April 1, 1999
Partner: UNT Libraries Government Documents Department

Policy issues facing the Comprehensive Test Ban Treaty and prospects for the future

Description: This report is divided into the following 5 sections: (1) Background; (2) Major Issues Facing Ratification of CTBT; (3) Current Status on CTBT Ratification; (4) Status of CTBT Signatories and Ratifiers; and (5) CTBT Activities Not Prohibited. The major issues facing ratification of CTBT discussed here are: impact on CTBT of START II and ABM ratification; impact of India and Pakistan nuclear tests; CTBT entry into force; and establishment of the Comprehensive Nuclear Test-Ban Treaty Organization.
Date: April 1, 1999
Creator: Sweeney, J.
Partner: UNT Libraries Government Documents Department

DOE handbook: Guide to good practices for the selection, training, and qualification of shift supervisors

Description: This Department of Energy (DOE) handbook is approved for use by all DOE Components and their contractors. The Handbook incorporates editorial changes to DOE-STD-1061-93, ``Guide to Good Practices for the Selection, Training, and Qualification of shift Supervisors,`` and supersedes DOE-STD-1061-93. Technical content of this Handbook has not changed from the original technical standard. Changes are primarily editorial improvements, redesignation of the standard to a Handbook, and format changes to conform with current Technical Standards Program procedures. This guide, used in conjunction with a facility-specific job analysis, provides a framework for the selection, training, qualification, and professional development of reactor facility and non-reactor nuclear facility shift supervisors. Training and qualification programs based on this guide should provide assurance that shift supervisors perform their jobs safely and competently.
Date: April 1, 1999
Partner: UNT Libraries Government Documents Department

Bayesian analysis of MEG visual evoked responses

Description: The authors developed a method for analyzing neural electromagnetic data that allows probabilistic inferences to be drawn about regions of activation. The method involves the generation of a large number of possible solutions which both fir the data and prior expectations about the nature of probable solutions made explicit by a Bayesian formalism. In addition, they have introduced a model for the current distributions that produce MEG and (EEG) data that allows extended regions of activity, and can easily incorporate prior information such as anatomical constraints from MRI. To evaluate the feasibility and utility of the Bayesian approach with actual data, they analyzed MEG data from a visual evoked response experiment. They compared Bayesian analyses of MEG responses to visual stimuli in the left and right visual fields, in order to examine the sensitivity of the method to detect known features of human visual cortex organization. They also examined the changing pattern of cortical activation as a function of time.
Date: April 1, 1999
Creator: Schmidt, D.M.; George, J.S. & Wood, C.C.
Partner: UNT Libraries Government Documents Department

Large-scale demonstration and deployment project at Los Alamos National Laboratory

Description: Established by the US Department of Energy (DOE) Environmental Management program through its Office of Science and Technology, the Deactivation and Decommissioning Focus Area is developing answers to the technological problems that hinder Environmental Management`s extensive cleanup efforts. The optimized application of technologies to ongoing nuclear facility decontamination and dismantlement is critical in meeting the challenge of decommissioning approximately 9,000 buildings and structures within the DOE complex. The significant technical and economic concerns in this area underscore a national imperative for the qualification and timely delivery of cost-reduction technologies and management approaches to meet federal and private needs. At Los Alamos National Laboratory (LANL), a Large-Scale Demonstration and Deployment Project (LSDDP) has been established to facilitate demonstration and deployment of technologies for the characterization, decontamination, and volume reduction of oversized metallic waste, mostly in the form of gloveboxes contaminated with transuranic radionuclides. The LANL LSDDP is being managed by an integrated contractor team (ICT) consisting of IT Corporation, ICF Incorporated, and Florida International University and includes representation from LANL`s Environmental Management Program Office. The ICT published in the Commerce Business Daily a solicitation for interest for innovative technologies capable of improving cost and performance of the baseline process. Each expression of interest response was evaluated and demonstration contract negotiations are under way for those technologies expected to be capable of meeting the project objectives. This paper discusses management organization and approach, the results of the technology search, the technology selection methodology, the results of the selection process, and future plans for the program.
Date: April 1, 1999
Creator: Brown, S.; McFee, J.; Broom, C.; Dugger, H. & Stallings, E.
Partner: UNT Libraries Government Documents Department

Office of Inspector General audit report on Westinghouse Savannah River Company`s withdrawal of fees

Description: As the operator of the Department`s Savannah River Site, Westinghouse Savannah River Company (Westinghouse) receives three types of fees: (1) award fees commensurate with the overall performance rating, (2) Performance Based Incentive (PBI) fees for achieving measurable goals or defined tasks as specified in annual operating plans, and (3) Cost Reduction Incentive Program (CRIP) fees for making improvements in site operations that reduce total contract costs. The Department`s Contracting Officer notifies Westinghouse when fees are earned, and Westinghouse withdraws the authorized amounts from the Department`s letter-of-credit account. The audit objective was to determine whether Westinghouse withdrew the appropriate amount of fees from the letter-of-credit account in Fiscal Years (FY) 1997 an 1998.
Date: April 1, 1999
Partner: UNT Libraries Government Documents Department

Low temperature anomaly of LO phonons in La{sub 1.85}Sr{sub 0.15}CuO{sub 4} and YBa{sub 2}Cu{sub 3}O{sub 7}

Description: Inelastic neutron scattering measurements of La{sub 1.85}Sr{sub 0.15}CuO{sub 4} and YBa{sub 2}Cu{sub 3}O{sub 7} show that the dispersion of the high energy LO phonon mode along the (1,0,0) direction is strongly temperature dependent, and at low temperatures develops an anomalous feature indicative of dynamic cell-doubling. The anomaly does not change through superconducting transition and gradually disappears between 50 and 250 K in LSCO. Possible implications are discussed.
Date: April 1999
Creator: Egami, T.; Petrov, Y.; McQueeney, R. J.; Yethiraj, M.; Shirane, G. & Endoh, Y.
Partner: UNT Libraries Government Documents Department

Ignition dynamics of high explosives

Description: The laser ignition of the explosives HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, C{sub 4}H{sub 8}N{sub 8}O{sub 8}), {delta}-phase HMX, PBX 9501 (95% HMX, 2.5% Estane, 2.5% BDNPA/BDNPF), TATB (1,3,5-triamino-2,4,6-trinitrobenzene, C{sub 6}H{sub 6}N{sub 6}O{sub 6}), and PBX 9502 (95% TATB, 5% Kel-F) and aged PBX 9502 has been conducted with the intent to compare the relative sensitivities of those explosives and to investigate the effect of beam profile, binder addition, and porosity. It has been found that there was little difference between a gaussian beam and a top hat profile on the laser ignition of HMX. The authors observe that the addition of binder in the amounts present in PBX 9501 resulted in longer ignition delays than that of HMX. In contrast to HMX, the addition of binder to TATB in PBX 9502 shows no measurable effect. Porosity effects were considered by comparing the ignition of granular HMX and pressed HMX pellets. Porosity appears to increase ignition delay due to an increased effective absorption scale and increased convective heat loss. This porosity effect also resulted in longer ignition delays for {delta}-phase HMX than for {beta}-phase HMX. In order to simulate ignition in voids or cracks, the standard ignition experiment was modified to include a NaCl window placed at variable distances above the sample surface. When ignition experiments were performed at 29 W/cm{sup 2} and 38 W/cm{sup 2} a critical gap distance was observed of 6 {+-} 0.4 mm below which ignition was severely inhibited. This result underscores the importance of gas phase processes in ignition and illustrates that conditions can exist where simple ignition criteria such as surface temperature is inadequate.
Date: April 1, 1999
Creator: Ali, A.N.; Son, S.F.; Sander, R.K.; Asay, B.W. & Brewster, M.Q.
Partner: UNT Libraries Government Documents Department