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AB INITIO AND CALPHAD THERMODYNAMICS OF MATERIALS (open access)

AB INITIO AND CALPHAD THERMODYNAMICS OF MATERIALS

Ab initio electronic structure methods can supplement CALPHAD in two major ways for subsequent applications to stability in complex alloys. The first one is rather immediate and concerns the direct input of ab initio energetics in CALPHAD databases. The other way, more involved, is the assessment of ab initio thermodynamics {acute a} la CALPHAD. It will be shown how these results can be used within CALPHAD to predict the equilibrium properties of multi-component alloys.
Date: April 14, 2004
Creator: Turchi, P A
Object Type: Article
System: The UNT Digital Library
Activation Energy for Grain Growth in Aluminum Coatings (open access)

Activation Energy for Grain Growth in Aluminum Coatings

To produce a specific grain size in metallic coatings requires precise control of the time at temperature during the deposition process. Aluminum coatings are deposited using electron-beam evaporation onto heated substrate surfaces. The grain size of the coating is determined upon examination of the microstructure in plan view and cross-section. Ideal grain growth is observed over the entire experimental range of temperature examined from 413 to 843 K. A transition in the activation energy for grain growth from 0.7 to 3.8 eV {center_dot} atom{sup -1} is observed as the temperature increases from <526 K to >588 K. The transition is indicative of the dominant mechanism for grain growth shifting with increasing temperature from grain boundary to lattice diffusion.
Date: October 14, 2004
Creator: Jankowski, Alan Frederic; Ferreira, J. L. & Hayes, Jeffrey P.
Object Type: Article
System: The UNT Digital Library
Adaptive 4-8 Texture Hierarchies (open access)

Adaptive 4-8 Texture Hierarchies

None
Date: April 14, 2004
Creator: Hwa, L M; Duchaineau, M A & Joy, K I
Object Type: Report
System: The UNT Digital Library
Advanced diffusion studies with isotopically controlled materials (open access)

Advanced diffusion studies with isotopically controlled materials

The use of enriched stable isotopes combined with modern epitaxial deposition and depth profiling techniques enables the preparation of material heterostructures, highly appropriate for self- and foreign-atom diffusion experiments. Over the past decade we have performed diffusion studies with isotopically enriched elemental and compound semiconductors. In the present paper we highlight our recent results and demonstrate that the use of isotopically enriched materials ushered in a new era in the study of diffusion in solids which yields greater insight into the properties of native defects and their roles in diffusion. Our approach of studying atomic diffusion is not limited to semiconductors and can be applied also to other material systems. Current areas of our research concern the diffusion in the silicon-germanium alloys and glassy materials such as silicon dioxide and ion conducting silicate glasses.
Date: November 14, 2004
Creator: Bracht, Hartmut A.; Silvestri, Hughes H. & Haller, Eugene E.
Object Type: Article
System: The UNT Digital Library
ADVANCED TECHNOLOGIES FOR STRIPPER GAS WELL ENHANCEMENT (open access)

ADVANCED TECHNOLOGIES FOR STRIPPER GAS WELL ENHANCEMENT

As part of Task 1 in Advanced Technologies for Stripper Gas Well Enhancement, Schlumberger Data & Consulting Services (DCS) joined with two Appalachian Basin producers, Great Lakes Energy Partners, LLC, and Belden & Blake Corporation to develop methodologies for identification and enhancement of stripper wells with economic upside potential. These industry partners previously provided us with data for more than 700 wells in northwestern Pennsylvania. Phase 1 goals of this project are to develop and validate methodologies that can quickly and cost-effectively identify underperforming wells with remediation potential. We have enhanced and streamlined our software and are using it with the latest versions of Microsoft's{trademark} Access and Excel programs. During the last quarter of 2002, Great Lakes provided us with additional data for approximately 2,200 wells located in their Cooperstown field situated in northwestern Pennsylvania. We identified approximately 130 potential remediation candidates, and Great Lakes personnel are currently reviewing this list for viable remediation. Within the last few weeks, a list of five candidates have been chosen for refract, in addition to two alternate wells. This field has provided a rigorous test of our software and analytical methods. We have processed all the information provided to us including the Cooperstown …
Date: July 14, 2004
Creator: MacDonald, Ronald J.
Object Type: Report
System: The UNT Digital Library
Advanced Technologies for Stripper Gas Well Enhancement (open access)

Advanced Technologies for Stripper Gas Well Enhancement

This report addresses a quarterly report about the advanced technologies of stripper gas well enhancement from July 1 to September 30, 2003
Date: July 14, 2004
Creator: MacDonald, Ronald J.
Object Type: Report
System: The UNT Digital Library
Advanced Technologies for Stripper Gas Well Enhancement (open access)

Advanced Technologies for Stripper Gas Well Enhancement

This report summarizes a quarterly report of the advanced technologies for stripper gas well enhancement during January 1 to March 31, 2004.
Date: July 14, 2004
Creator: MacDonald, Ronald J.
Object Type: Report
System: The UNT Digital Library
Advanced Technologies for Stripper Gas Well Enhancement (open access)

Advanced Technologies for Stripper Gas Well Enhancement

This report addresses a quarterly report of the advanced technologies for stripper gas well enhancement.
Date: July 14, 2004
Creator: MacDonald, Ronald J.
Object Type: Report
System: The UNT Digital Library
Advancing Climate and Carbon Simulation (open access)

Advancing Climate and Carbon Simulation

We use a recently developed integrated climate/carbon model to perform breakthrough studies of the climate. Two major studies are carried out--namely the effects of CO{sub 2}-fertilized vegetation on global climate and carbon dynamics, and the effect of climate sensitivity on carbon cycle feedback. We have also begun development of a next-generation climate/carbon modeling capability.
Date: December 14, 2004
Creator: Thompson, S.
Object Type: Report
System: The UNT Digital Library
Agricultural and Environmental Input Parameters for the Biosphere Model (open access)

Agricultural and Environmental Input Parameters for the Biosphere Model

This analysis is one of 10 technical reports that support the Environmental Radiation Model for Yucca Mountain Nevada (ERMYN) (i.e., the biosphere model). It documents development of agricultural and environmental input parameters for the biosphere model, and supports the use of the model to develop biosphere dose conversion factors (BDCFs). The biosphere model is one of a series of process models supporting the total system performance assessment (TSPA) for the repository at Yucca Mountain. The ERMYN provides the TSPA with the capability to perform dose assessments. A graphical representation of the documentation hierarchy for the ERMYN is presented in Figure 1-1. This figure shows the interrelationships between the major activities and their products (the analysis and model reports) that were planned in ''Technical Work Plan for Biosphere Modeling and Expert Support'' (BSC 2004 [DIRS 169573]). The ''Biosphere Model Report'' (BSC 2004 [DIRS 169460]) describes the ERMYN and its input parameters.
Date: September 14, 2004
Creator: Rasmuson, K. & Rautenstrauch, K.
Object Type: Report
System: The UNT Digital Library
Algebraic sub-structuring for electromagnetic applications (open access)

Algebraic sub-structuring for electromagnetic applications

Algebraic sub-structuring refers to the process of applying matrix reordering and partitioning algorithms to divide a large sparse matrix into smaller submatrices from which a subset of spectral components are extracted and combined to form approximate solutions to the original problem. In this paper, we show that algebraic sub-structuring can be effectively used to solve generalized eigenvalue problems arising from the finite element analysis of an accelerator structure.
Date: September 14, 2004
Creator: Yang, Chao; Gao, Weiguo; Bai, Zhaojun; Li, Xiaoye; Lee, Lie-Quan; Husbands, Parry et al.
Object Type: Article
System: The UNT Digital Library
Annual Report for LDRD-04-FS-019 The Innermost Inner Core: Fact or Artifact? (open access)

Annual Report for LDRD-04-FS-019 The Innermost Inner Core: Fact or Artifact?

There is considerable debate in the Earth sciences over the composition, thermal history, and dynamics of Earth's inner core. The details of structural models are based on precious few seismological observations of PKP travel times, due to the uneven distribution of large earthquakes and recording stations around the globe. Using state-of-the-art signal-processing techniques to measure and compile a unique set of global travel time data of surface-reflected seismic waves that propagate through the center of Earth (PKPPKP waves), we propose to investigate the existence of the innermost inner core. We will carry out a systematic investigation to determine the configuration of inner core anisotropy, which is currently biased by a limited spatial sampling of the inner core by PKP waves. We expect to collect data set of waveforms and identify PKPPKP energy arrivals on existing seismological records in a systematic form. We expect to demonstrate whether or not the existence of the innermost inner core can be supported by seismological data and to provide major constraints on the amount of inner core anisotropy. This is a topic of very high interest in the earth science community and the results would be of great importance not only to seismologists but to …
Date: October 14, 2004
Creator: Tkalcic, H & Flanagan, M P
Object Type: Report
System: The UNT Digital Library
Assessing Terrorist Motivations for Attacking Critical "Chemical" Infrastructure (open access)

Assessing Terrorist Motivations for Attacking Critical "Chemical" Infrastructure

Certain types of infrastructure--critical infrastructure (CI)--play vital roles in underpinning our economy, security, and way of life. One particular type of CI--that relating to chemicals--constitutes both an important element of our nation's infrastructure and a particularly attractive set of potential targets. This is primarily because of the large quantities of toxic industrial chemicals (TICs) it employs in various operations and because of the essential economic functions it serves. This study attempts to minimize some of the ambiguities that presently impede chemical infrastructure threat assessments by providing new insight into the key motivational factors that affect terrorist organizations propensity to attack chemical facilities. Prepared as a companion piece to the Center for Nonproliferation Studies August 2004 study--''Assessing Terrorist Motivations for Attacking Critical Infrastructure''--it investigates three overarching research questions: (1) why do terrorists choose to attack chemical-related infrastructure over other targets; (2) what specific factors influence their target selection decisions concerning chemical facilities; and (3) which, if any, types of groups are most inclined to attack chemical infrastructure targets? The study involved a multi-pronged research design, which made use of four discrete investigative techniques to answer the above questions as comprehensively as possible. These include: (1) a review of terrorism and threat …
Date: December 14, 2004
Creator: Ackerman, G.; Bale, J. & Moran, K.
Object Type: Report
System: The UNT Digital Library
Axial and Temporal Gradients in Mo Z Pinches (open access)

Axial and Temporal Gradients in Mo Z Pinches

Three nested molybdenum wire arrays with initial outer diameters of 45, 50, and 55 mm were imploded by the {approx} 20 MA, 90 ns rise-time current pulse of Sandia's Z accelerator. The implosions generated Mo plasmas with approximately 10% of the array's initial mass reaching Ne-like and nearby ionization stages. These ions emitted 2 - 4 keV L-shell x-rays with radiative powers approaching 10 TW. Mo L-shell spectra with axial and temporal resolution were captured and have been analyzed using a non-LTE collisional-radiative model. We find significant axial variation in the plasma conditions, with electron densities increasing from the cathode ({approx} 3 x 10{sup 20}cm{sup -3}) to near the anode end of the plasma ({approx} 3 x 10{sup 21}cm{sup -3}) and electron temperatures decreasing slightly from the cathode ({approx} 1.7 keV) to the anode end ({approx} 1.5 keV). Time-resolved spectra indicate that the peak electron density is reached before the peak of the L-shell emission and decreases with time, while the electron temperature remains within 10% of 1.7 keV over the 20 - 30 ns L-shell radiation pulse. Finally, while the total yield, peak total power, and peak L-shell power all tended to decrease with increasing initial wire array diameters, …
Date: July 14, 2004
Creator: LePell, P D; Hansen, S B; Shlyaptseva, A S; Coverdale, C; Deeney, C; Apruzese, J P et al.
Object Type: Article
System: The UNT Digital Library
Can fuzzy logic bring complex problems into focus? Modeling imprecise factors in environmental policy (open access)

Can fuzzy logic bring complex problems into focus? Modeling imprecise factors in environmental policy

In modeling complex environmental problems, we often fail to make precise statements about inputs and outcome. In this case the fuzzy logic method native to the human mind provides a useful way to get at these problems. Fuzzy logic represents a significant change in both the approach to and outcome of environmental evaluations. Risk assessment is currently based on the implicit premise that probability theory provides the necessary and sufficient tools for dealing with uncertainty and variability. The key advantage of fuzzy methods is the way they reflect the human mind in its remarkable ability to store and process information which is consistently imprecise, uncertain, and resistant to classification. Our case study illustrates the ability of fuzzy logic to integrate statistical measurements with imprecise health goals. But we submit that fuzzy logic and probability theory are complementary and not competitive. In the world of soft computing, fuzzy logic has been widely used and has often been the ''smart'' behind smart machines. But it will require more effort and case studies to establish its niche in risk assessment or other types of impact assessment. Although we often hear complaints about ''bright lines,'' could we adapt to a system that relaxes these …
Date: June 14, 2004
Creator: McKone, Thomas E. & Deshpande, Ashok W.
Object Type: Report
System: The UNT Digital Library
Characterization of U(VI) Sorption-Desorption Processes and Model Upscaling (open access)

Characterization of U(VI) Sorption-Desorption Processes and Model Upscaling

The objectives of the overall collaborative EMSP effort (with which this project is associated) are to characterize sorption and desorption processes of U(VI) on pristine and contaminated Hanford sediments over a range of sediment facies and materials properties and to relate such characterization both to fundamental molecular-scale understanding and fieldscale models of geochemistry and mass transfer. The research is intended to provide new insights on the mechanisms of U(VI) retardation at Hanford, and to allow the development of approaches by which laboratory-developed geochemical models can be upscaled for defensible field-scale predictions of uranium transport in the environment.
Date: June 14, 2004
Creator: Zachara, John M.; Brown, Gordon, E.; Lichtner, Peter C. & Ball, William
Object Type: Report
System: The UNT Digital Library
Characterize Framework for Igneous Activity at Yucca Mountain, Nevada (open access)

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada

The purpose of this scientific analysis report is threefold: (1) Present a conceptual framework of igneous activity in the Yucca Mountain region (YMR) consistent with the volcanic and tectonic history of this region and the assessment of this history by experts who participated in the probabilistic volcanic hazard analysis (PVHA) (CRWMS M&O 1996 [DIRS 100116]). Conceptual models presented in the PVHA are summarized and applied in areas in which new information has been presented. Alternative conceptual models are discussed, as well as their impact on probability models. The relationship between volcanic source zones defined in the PVHA and structural features of the YMR are described based on discussions in the PVHA and studies presented since the PVHA. (2) Present revised probability calculations based on PVHA outputs for a repository footprint proposed in 2003 (BSC 2003 [DIRS 162289]), rather than the footprint used at the time of the PVHA. This analysis report also calculates the probability of an eruptive center(s) forming within the repository footprint using information developed in the PVHA. Probability distributions are presented for the length and orientation of volcanic dikes located within the repository footprint and for the number of eruptive centers (conditional on a dike intersecting the …
Date: October 14, 2004
Creator: Perry, F. & Youngs, R.
Object Type: Report
System: The UNT Digital Library
The CKM matrix and CP violation (open access)

The CKM matrix and CP violation

The status of CP violation and the CKM matrix is reviewed. Direct CP violation in B decay has been established and the measurement of sin 2{beta} in {psi}K modes reached 5% accuracy. I discuss the implications of these, and of the possible deviations of the CP asymmetries in b {yields} s modes from that in {psi}K. The first meaningful measurements of {alpha} and {gamma} are explained, together with their significance for constraining both the SM and new physics in B-{bar B} mixing. I also discuss implications of recent developments in the theory of nonleptonic decays for B {yields} {pi}K rates and CP asymmetries, and for the polarization in charmless B decays to two vector mesons.
Date: September 14, 2004
Creator: Ligeti, Zoltan
Object Type: Article
System: The UNT Digital Library
Classroom HVAC: Improving ventilation and saving energy -- field study plan (open access)

Classroom HVAC: Improving ventilation and saving energy -- field study plan

The primary goals of this research effort are to develop, evaluate, and demonstrate a very practical HVAC system for classrooms that consistently provides classrooms (CRs) with the quantity of ventilation in current minimum standards, while saving energy, and reducing HVAC-related noise levels. This research is motivated by the public benefits of energy efficiency, evidence that many CRs are under-ventilated, and public concerns about indoor environmental quality in CRs. This document provides a summary of the detailed plans developed for the field study that will take place in 2005 to evaluate the energy and IAQ performance of a new classroom HVAC technology. The field study will include measurements of HVAC energy use, ventilation rates, and IEQ conditions in 10 classrooms with the new HVAC technology and in six control classrooms with a standard HVAC system. Energy use and many IEQ parameters will be monitored continuously, while other IEQ measurements will be will be performed seasonally. Continuously monitored data will be remotely accessed via a LonWorks network. Instrument calibration plans that vary with the type of instrumentation used are established. Statistical tests will be employed to compare energy use and IEQ conditions with the new and standard HVAC systems. Strengths of this …
Date: October 14, 2004
Creator: Apte, Michael G.; Faulkner, David; Hodgson, Alfred T. & Sullivan, Douglas P.
Object Type: Report
System: The UNT Digital Library
Closure Plan for the E-Area Low-Level Waste Facility (open access)

Closure Plan for the E-Area Low-Level Waste Facility

To comply with the applicable requirements of the U.S. Department of Energy (US DOE), this closure plan has been developed for the E-Area Low-Level Waste Facility(LLWF). The plan is organized according to the specifications of the Format and Content Guide for U.S. Department of Energy Low-Level Waste Disposal Facility Closure Plans. Section 2 provides a brief overview of the general facility description, closure approach, closure schedule, related activities, and key assumptions. Sections 3 and 4 provide specific details of facility characteristics and the technical approach to closure, respectively, as well as supporting information. Additional schedule details are provided in Section 5. Section 6 provides a list of recommended items for consideration in association with future revisions to the E-Area LLWF Closure Plan and Performance Assessment (PA). Operation of the E-Area LLWF began with placement of the first low-level waste box within the Low Activity Waste (LAW) Vault. It is anticipated that operations will continue for at least 25 years, and that a 100-year institutional control period will follow cessation of operations. It is further anticipated that closure will be conducted in the following three phases: operational closure, interim closure, and final closure. Operational closure will be conducted during the 25 …
Date: July 14, 2004
Creator: PHIFER, MARKA.l
Object Type: Report
System: The UNT Digital Library
COAMPS Application to Global and Homeland Security Threat Problems (open access)

COAMPS Application to Global and Homeland Security Threat Problems

Atmospheric dispersion problems have received more attention with regard to global and homeland security than their conventional roles in air pollution and local hazard assessment in the post 9/11 era. Consequently, there is growing interest to characterize meteorology uncertainty at both low and high altitudes (below and above 30 km, respectively). A 3-D Coupled Ocean Atmosphere Prediction System (COAMPS, developed by Naval Research Laboratory; Hodur, 1997) is used to address LLNL's task. The objective of this report is focused on the effort at the improvement of COAMPS forecast to address the uncertainty issue, and to provide new capability for high-altitude forecast. To assess the atmospheric dispersion behavior in a wider range of meteorological conditions and to expand its vertical scope for the potential threat at high altitudes, several modifications of COAMPS are needed to meet the project goal. These improvements include (1) the long-range forecast capability to show the variability of meteorological conditions at a much larger time scale (say, a year), and (2) the model physics enhancement to provide new capability for high-altitude forecast.
Date: September 14, 2004
Creator: Chin, H S & Glascoe, L G
Object Type: Report
System: The UNT Digital Library
Coherent parasitic energy loss of the recycler beam (open access)

Coherent parasitic energy loss of the recycler beam

Parasitic energy loss of the particle beam in the Recycler Ring is discussed. The long beam confined between two barrier waves has a spectrum that falls off rapidly with frequency. Discrete summation over the revolution harmonics must be made to obtain the correct energy loss per particle per turn, because only a few lower revolution harmonics of real part of the longitudinal impedance contribute to the parasitic energy loss. The longitudinal impedances of the broadband rf cavities, the broadband resistive-wall monitors, and the resistive wall of the vacuum chamber are discussed. They are the main sources of the parasitic energy loss.
Date: July 14, 2004
Creator: Ng, King-Yuen
Object Type: Report
System: The UNT Digital Library
Comment on ''Thermal Behavior of Polarized Pd/D Electrodes Prepared by Co-Deposition'' (open access)

Comment on ''Thermal Behavior of Polarized Pd/D Electrodes Prepared by Co-Deposition''

This paper presents the basics of this model, including what physical conditions could produce a calibration constant shift and what might cause those conditions to arise. The new evidences are discussed and it is shown that the possibility of at-the-electrode recombination cannot be eliminated, in fact prior photographic evidence is shown to be reasonable evidence of this phenomenon. Thus in the absence of definitive data, the conclusion that apparent excess heat arises from a nuclear cause is premature. If the apparent excess heat signal is not representative of a true heat source, but is instead an equipment/method malfunction, integrating the signal is of no value. This paper proposes that is the situation, and will therefore focus on examining the phenomenon of apparent excess enthalpy (sometimes called excess heat). Not addressed will be the myriad of other purported evidences of nuclear reactions. The apparent excess heat claims form the largest block of claims for a nuclear FPHE cause, and the correlation of apparent excess heat with apparent nuclear ash detection is often cited as evidence of the nuclear nature of the FPHE. But confidence in the validity of the apparent excess heat signal is of critical importance in validating a nuclear …
Date: July 14, 2004
Creator: SHANAHAN, KIRKL.
Object Type: Article
System: The UNT Digital Library
A Component Architecture for High-Performance Scientific Computing (open access)

A Component Architecture for High-Performance Scientific Computing

The Common Component Architecture (CCA) provides a means for software developers to manage the complexity of large-scale scientific simulations and to move toward a plug-and-play environment for high-performance computing. In the scientific computing context, component models also promote collaboration using independently developed software, thereby allowing particular individuals or groups to focus on the aspects of greatest interest to them. The CCA supports parallel and distributed computing as well as local high-performance connections between components in a language-independent manner. The design places minimal requirements on components and thus facilitates the integration of existing code into the CCA environment. The CCA model imposes minimal overhead to minimize the impact on application performance. The focus on high performance distinguishes the CCA from most other component models. The CCA is being applied within an increasing range of disciplines, including combustion research, global climate simulation, and computational chemistry.
Date: December 14, 2004
Creator: Bernholdt, D. E.; Allan, B. A.; Armstrong, R.; Bertrand, F.; Chiu, K.; Dahlgren, T. L. et al.
Object Type: Article
System: The UNT Digital Library