The Controller Synthesis of Metastable Oxides Utilizing Epitaxy and Epitaxial Stabilization (open access)

The Controller Synthesis of Metastable Oxides Utilizing Epitaxy and Epitaxial Stabilization

Molecular beam epitaxy (MBE) has achieved unparalleled control in the integration of semiconductors at the nanometer. These advances were made through the use of epitaxy, epitaxial stabilization, and a combination of composition-control techniques including adsorption-controlled growth and RHEED-based composition control that we have developed, understood, and utilized for the growth of oxides. Also key was extensive characterization (utilizing RHEED, four-circle x-ray diffraction, AFM, TEM, and electrical characterization techniques) in order to study growth modes, optimize growth conditions, and probe the structural, dielectric, and ferroelectric properties of the materials grown. The materials that we have successfully engineered include titanates (PbTiO3, Bi4Ti3O12), tantalates (SrBi2Ta2O9), and niobates (SrBi2Nb2O9); layered combinations of these perovskite-related materials (Bi4Ti3O12-SrTiO3 and Bi4Ti3O12-PbTiO3 Aurivillius phases and metastable PbTiO3/SrTiO3 and BaTiO3/SrTiO3 superlattices), and new metastable phases (Srn+1TinO3n+1 Ruddlesden-Popper phases). The films were grown by reactive MBE and pulsed laser deposition (PLD). Many of these materials are either new or have been synthesized with the highest perfection ever reported. The controlled synthesis of such layered oxide heterostructures offers great potential for tailoring the superconducting, ferroelectric, and dielectric properties of these materials. These properties are important for energy technologies.
Date: December 2, 2003
Creator: Schlom, Darrell
Object Type: Report
System: The UNT Digital Library
Disposition of Tank 48H Organics by Fluidized Bed Steam Reforming (FBSR) (open access)

Disposition of Tank 48H Organics by Fluidized Bed Steam Reforming (FBSR)

In order to make space in the Savannah River Site Tank farm, the Tank 48H waste must be removed. Therefore, the Tank 48H waste must be processed to reduce or eliminate levels of nitrates, nitrites, and sodium tetraphenyl borate in order to reduce impacts of these species before it is vitrified. Fluidized Bed Steam Reforming is being considered as a candidate technology for destroying the nitrates and the NaTPB prior to melting. The Idaho National Engineering and Environmental Laboratory was tasked to perform a proof-of-concept steam reforming test to evaluate the technical feasibility for pretreating the Tank 48H waste. The crucible (bench scale) tests conducted at the Savannah River Technology Center were initiated to optimize and augment the parameters subsequently tested at the pilot scale at INEEL. The purposes of the current study, organic destruction and downstream processing of T48H waste slurry were fulfilled. TPB was destroyed in all 19 samples tested with the simulated FB SR process at operational temperatures 650-725 degrees Celsius. A test temperature of 650 degrees Celsius optimized NO3 destruction during the formation of an Na2CO3 FBSR product. A test temperature of 725 degrees Celsius optimized NO3 destruction during formation of a sodium silicate FBSR product. …
Date: December 2, 2003
Creator: Jantzen, Carol M.
Object Type: Report
System: The UNT Digital Library
Evaluation of the Effects of Tank 50H Solids on Dissolved Uranium, Plutonium and Neptunium (open access)

Evaluation of the Effects of Tank 50H Solids on Dissolved Uranium, Plutonium and Neptunium

The study of the effects of contacting a simulated salt solution spiked with uranium, plutonium, and neptunium with Tank 50H solids. General findings include: There is no evidence for interaction between Tank 50H solids and uranium from the spiked salt solution. Lack of uranium removal may reflect prior removal of uranium. There is evidence for interaction between Tank 50H solids with plutonium and neptunium as evidenced by loss of these two actinides from the salt solution. The amount of plutonium and neptunium lost from solution increased with an increase in the quantity of Tank 50H solids for a fixed simulant volume. The removal of plutonium and neptunium fit typical sorption isotherms allowing development of loading curves for estimating maximum solids loading. The maximum loading capacities for plutonium and neptunium in the simulants are, respectively, 2.01 and 4.48 micrograms per gram of Tank 50H solids. The oxalate in the Tank 50H solids is not directly responsible for the loss of plutonium and neptunium from the salt solution. The removal of plutonium and neptunium may be attributed to other minor components of the Tank 50H solids. We recommend additional testing to identify the component responsible for the plutonium and neptunium removal.
Date: December 2, 2003
Creator: Oji, L.N.
Object Type: Report
System: The UNT Digital Library
The Impact of Higher Waste Loading on Glass Properties: The Effects of Uranium and Thorium (open access)

The Impact of Higher Waste Loading on Glass Properties: The Effects of Uranium and Thorium

In this study, glasses are designed or selected to assess the impacts of U3O8 and ThO2 on various glass properties of interest. More specifically, glasses were fabricated in which Th replaced U (on a molar basis) to assess the impact of ThO2 on the durability response (as measured by the Product Consistency Test ) and viscosity. Based on the measured normalized boron release values, the results indicated that the Th-enriched glasses were less durable than their Ubased counterparts. Although molar substitution of Th or U had a negative impact, all of the glasses were more durable than the Environmental Assessment glass - the highest release being 7.39 g/L as compared to 16.695 g/L as reported for EA. With respect to model predictions, THERMOTM predicts that a molar substitution of thorium for uranium should increase glass durability. However, these data suggest that the signs and/or magnitudes of the Gi values associated with U3O8 and ThO2 are inconsistent with the theory on which the current model is based for the limited number of glasses tested. It should be noted that these glasses cover a narrow compositional region. With respect to the impact on viscosity, the data suggest that there may be a …
Date: December 2, 2003
Creator: Peeler, D.K.
Object Type: Report
System: The UNT Digital Library
Injection Into Electron Plasma Traps (open access)

Injection Into Electron Plasma Traps

Computational studies and experimental measurements of plasma injection into a Malmberg-Penning trap reveal that the number of trapped particles can be an order of magnitude higher than predicted by a simple estimates based on a ballistic trapping model. Enhanced trapping is associated with a rich nonlinear dynamics generated by the space-charge forces of the evolving trapped electron density. A particle-in-cell simulation is used to identify the physical mechanisms that lead to the increase in trapped electrons. The simulations initially show strong two-stream interactions between the electrons emitted from the cathode and those reflected off the end plug of the trap. This is followed by virtual cathode oscillations near the injection region. As electrons are trapped, the initially hollow longitudinal phase-space is filled, and the transverse radial density profile evolves so that the plasma potential matches that of the cathode. Simple theoretical arguments are given that describe the different dynamical regimes. Good agreement is found between simulation and theory.
Date: December 2, 2003
Creator: Gorgadze, Vladimir; Pasquini, Thomas A.; Fajans, Joel & Wurtele, Jonathan S.
Object Type: Article
System: The UNT Digital Library
Iraq’s Trade with the World: Data and Analysis (open access)

Iraq’s Trade with the World: Data and Analysis

None
Date: December 2, 2003
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Magnetic field perturbartions in closed-field-line systems with zero toroidal magnetic field (open access)

Magnetic field perturbartions in closed-field-line systems with zero toroidal magnetic field

In some plasma confinement systems (e.g., field-reversed configurations and levitated dipoles) the confinement is provided by a closed-field-line poloidal magnetic field. We consider the influence of the magnetic field perturbations on the structure of the magnetic field in such systems and find that the effect of perturbations is quite different from that in the systems with a substantial toroidal field. In particular, even infinitesimal perturbations can, in principle, lead to large radial excursions of the field lines in FRCs and levitated dipoles. Under such circumstances, particle drifts and particle collisions may give rise to significant neoclassical transport. Introduction of a weak regular toroidal magnetic field reduces radial excursions of the field lines and neoclassical transport.
Date: December 2, 2003
Creator: Mauel, M; Ryutov, D & Kesner, J
Object Type: Article
System: The UNT Digital Library
Military Personnel: Information on Selected National Guard Management Issues (open access)

Military Personnel: Information on Selected National Guard Management Issues

A letter report issued by the General Accounting Office with an abstract that begins "In the past few years, the nation's media have focused public attention on a series of misconduct and mismanagement issues within the Army National Guard and the Air National Guard. As part of the Bob Stump National Defense Authorization Act for fiscal year 2003, Congress directed GAO to examine four issues related to the management of the National Guard. In this report, GAO assesses the effectiveness of the (1) procedures that the Army National Guard and the Air National Guard have established and implemented to deal with service members who stop attending required training; (2) procedures that the National Guard uses for federally recognizing state promotions of senior National Guard officers; (3) process that the National Guard uses for disciplining senior officers (colonels and generals) who are guilty of misconduct; and (4) federal protections for National Guard members or civilian federal employees who report allegations of waste, fraud, abuse, or mismanagement (whistleblowers) and the extent to which disciplinary action is taken against those in the National Guard who retaliate against whistleblowers."
Date: December 2, 2003
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Pakistan: Chronology of Events (open access)

Pakistan: Chronology of Events

None
Date: December 2, 2003
Creator: Kronstadt, K. Alan
Object Type: Report
System: The UNT Digital Library
Pakistan-U.S. Relations (open access)

Pakistan-U.S. Relations

None
Date: December 2, 2003
Creator: Kronstadt, K. Alan
Object Type: Report
System: The UNT Digital Library
Purchase Cards: Steps Taken to Improve DOD Program Management, but Actions Needed to Address Misuse (open access)

Purchase Cards: Steps Taken to Improve DOD Program Management, but Actions Needed to Address Misuse

A letter report issued by the General Accounting Office with an abstract that begins "This study responds to a legislative mandate, which directs the Comptroller General to review the actions taken by the Department of Defense (DOD) to implement provisions included in the Bob Stump National Defense Authorization Act for fiscal year 2003 (Public Law 107-314) concerning management of the purchase card program. This study also discusses DOD efforts to implement provisions in the DOD Appropriations Act for fiscal year 2003 (Public Law 107-248) as well as recommendations and the status of disciplinary actions taken against individuals identified in prior GAO reports as having used the government purchase card for potentially fraudulent, improper, and abusive or questionable purposes."
Date: December 2, 2003
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
TAO users manual. (open access)

TAO users manual.

The Toolkit for Advanced Optimization (TAO) focuses on the design and implementation of component-based optimization software for the solution of large-scale optimization applications on high-performance architectures. Their approach is motivated by the scattered support for parallel computations and lack of reuse of linear algebra software in currently available optimization software. The TAO design allows the reuse of toolkits that provide lower-level support (parallel sparse matrix data structures, preconditioners, solvers), and thus they are able to build on top of these toolkits instead of having to redevelop code. The advantages in terms of efficiency and development time are significant. The TAO design philosophy uses object-oriented techniques of data and state encapsulation, abstract classes, and limited inheritance to create a flexible optimization toolkit. This chapter provides a short introduction to the design philosophy by describing the objectives in TAO and the importance of this design. Since a major concern in the TAO project is the performance and scalability of optimization algorithms on large problems, they also present some performance results.
Date: December 2, 2003
Creator: Benson, S.; McInnes, L. C.; More, J. J. & Sarich, J.
Object Type: Report
System: The UNT Digital Library
Waste Tank Heel Chemical Cleaning Summary (open access)

Waste Tank Heel Chemical Cleaning Summary

At the Savannah River Site in Aiken, South Carolina, there are approximately 40 million gallons of legacy High Level Waste stored in large capacity sub-surface tanks. Twelve of these tanks are single-containment, non-conforming tanks with leaks. These tanks were built in the 1950s. Some of these tanks contain sludge heels and are being considered for near-term removal efforts and vitrification. Currently, only mechanical methods (i.e., pumps) are used to remove the sludge waste with varying degrees of success. To provide for additional levels of removal, chemically-aided techniques are being considered. The objective of the was to collect and evaluate information available on chemical-based methods for removing residual solids from the Site's waste tanks. As part of this study, the team was requested to develop recommendations for chemical treatments to remove residual heels (primarily sludge). Ideally, one agent alone would be efficient at dissolving all residual tank heels and yet satisfy all safety and process concerns. No such chemical cleaning agent was found. The cleaning agents identified from the literature, included oxalic acid, a mixture of oxalic acid and citric acid, a combination of oxalic acid with hydrogen peroxide, nitric acid, formic acid, and organics. A criteria matrix for evaluating the …
Date: December 2, 2003
Creator: Barnes, M.J.
Object Type: Report
System: The UNT Digital Library
Coarse-Grained Molecular Dynamics for Computer Modeling of Nanomechanical Systems (open access)

Coarse-Grained Molecular Dynamics for Computer Modeling of Nanomechanical Systems

Unique challenges for computer modeling and simulation arise in the course of the development and design of nanoscale mechanical systems. Materials often exhibit unconventional behavior at the nanoscale that can affect device operation and failure. This uncertainty poses a problem because of the limited experimental characterization at these ultra-small length scales. In this Article we give an overview of how we have used concurrent multiscale modeling techniques to address some of these issues. Of particular interest are the dynamic and temperature-dependent processes found in nanomechanical systems. We focus on the behavior of sub-micron mechanical components of Micro-Electro-Mechanical Systems (MEMS) and Nano-Electro-Mechanical Systems (NEMS), especially flexural-mode resonators. The concurrent multiscale methodology we have developed for NEMS employs an atomistic description of millions of atoms in relatively small but key regions of the system, coupled to, and run concurrently with, a generalized finite element model of the periphery. We describe two such techniques. The more precise model, Coarse-Grained Molecular Dynamics (CGMD), describes the dynamics on a mesh of elements, but the equations of motion are built up from the underlying atomistic physics to ensure a smooth coupling between regions governed by different length scales. In many cases the degrees of smoothness of …
Date: November 2, 2003
Creator: Rudd, R E
Object Type: Article
System: The UNT Digital Library

Combinatorial Spray-Based Synthesis of PEM FC Electrocatalysts

This report talks about Combinatorial Spray-Based Synthesis of PEM FC Electrocatalysts
Date: November 2, 2003
Creator: Atanassova, Paolina; Bhatia, Rimple; Brewster, James; Dericotte, David; Gurau, Bogdan; Napolitano, Paul et al.
Object Type: Presentation
System: The UNT Digital Library
Activation Cross Sections Improvements needed for IFE Power Reactors Designs (open access)

Activation Cross Sections Improvements needed for IFE Power Reactors Designs

Uncertainties in the prediction of the neutron induced long-lived activity in the natural elements from H to Bi due to activation cross section uncertainties are estimated assuming as neutron environment those of the HYLIFE-II and Sombrero vessel structures. The latest available activation cross section data are employed. The random variables used in the uncertainty analysis have been the concentration limits (CL's) corresponding to hands-on recycling, remote recycling and shallow land burial, quantities typically considered in ranking elements under waste management considerations. The CL standard value (CL{sub nom}), i.e. without uncertainties, is compared with the 95th percentile CL value (CL95). The results of the analysis are very helpful in assessing the quality of the current activation data for IFE applications, providing a rational basis for programmatic priority assignments for new cross sections measurements or evaluations. The HYLIFE-II results shown that a significant error is estimated in predicting the activation of several elements. The estimated errors in the Sombrero case are much less important.
Date: October 2, 2003
Creator: Rodriguez, A; Cabellos, O; Sanz, J; FalQuina, R; Latkowski, J & Reyes, S
Object Type: Article
System: The UNT Digital Library
The Alien Tort Statute: Legislative History and Executive Branch Views (open access)

The Alien Tort Statute: Legislative History and Executive Branch Views

The report provides a historical overview of court decisions interpreting the Alien Tort Statute (ATS), also known as the Alien Tort Claims Act (ACTA). The report then provides an overview of the positions taken by the U.S. government in published opinions of the Attorney General and in court briefs related to ATS claims.
Date: October 2, 2003
Creator: Elsea, Jennifer K.
Object Type: Report
System: The UNT Digital Library
Application of a Device for Uniform Web Drying and Preheating Using Microwave Energy (open access)

Application of a Device for Uniform Web Drying and Preheating Using Microwave Energy

The project summarized in this report dealt with an evaluation of new microwave applicator ideas for paper preheating and drying. The technical basis for success in this project is the fact that Industrial Microwave Systems has recently identified certain previously unrecognized wave guide ''design variables'' and hardware implementation concepts that can be employed to greatly improve the uniformity of microwave energy distribution for continuous flow processes. Two applicator concepts were ultimately evaluated, a Cross-Machine Direction (CD) oriented applicator and a Machine Direction (MD) oriented applicator. The economic basis for success is the result of several factors. Since 1985, the capital expenditure required for an industrial microwave applicator system has decreased by a factor of four. The maintenance costs have decreased by a factor of 10 and the life expectancy of the magnetron has increased by more than a factor of four to in excess of 8,000 hours (nearly one year at 24 hours/day operation).
Date: October 2, 2003
Creator: Ahrens, Frederick W.; Habeger, C.; Loughran, J. & Patterson, T.
Object Type: Report
System: The UNT Digital Library
Binder/HMX interaction in PBX9501 at Elevated Temperatures (open access)

Binder/HMX interaction in PBX9501 at Elevated Temperatures

Plastic bonded explosives (PBX) generally consist of 85 - 95 % by weight energetic material, such as HMX, and 5 - 15 % polymeric binder. Understanding of the structure and morphology at elevated temperatures and pressures is important for predicting of PBX behavior in accident scenarios. The crystallographic behavior of pure HMX has been measured as functions of temperature and grain size. The investigation is extended to the high temperature behavior of PBX 9501 (95% HMX, 2.5 % Estane, 2.5 % BDNPA/F). The results show that the HMX {beta}-phase to {delta}-phase transition in PBX 9501 is similar to that in neat HMX. However, in the presence of the PBX 9501 binder, {delta}-phase HMX readily converts back to {beta}-phase during cooling. Using the same temperature profile, the conversion rate decreases for each subsequent heating and cooling cycle. As observed in earlier experiments, no reverse conversion is observed without the polymer binder. It is proposed that the reversion of {delta}-phase to {beta}-phase is due to changes in the surface molecular potential caused by the influence of the polymer binder on the surface molecules of the {delta}-phase. Upon thermal cycling, the polymer binder segregates from the HMX particles and thus reduces the influence …
Date: October 2, 2003
Creator: K., S C & M., T C
Object Type: Article
System: The UNT Digital Library
As-built model generation for a cylindrical test object (open access)

As-built model generation for a cylindrical test object

The goal of the As Built Model Development (ABMD) project in ADAPT is to determine how to produce finite element (FEM) meshes from information obtained from nondestructive inspection of parts and assemblies. These meshes could then be used in computational analysis tools to predict the actual performance of the parts, as opposed to the design performance that is obtained using meshes derived from design information. Information derived from several inspection methods could be used to derive the meshes, with some methods sensitive to geometry and others to material properties.
Date: October 2, 2003
Creator: Chambers, D. H.; Goodman, D. M. & Leach, R. R.
Object Type: Report
System: The UNT Digital Library
Capital Income Tax Revisions and Effective Tax Rates (open access)

Capital Income Tax Revisions and Effective Tax Rates

This report discusses several temporary provisions affecting the taxation of capital income that were adopted in the 2001-2003 period. These provisions include lower individual tax rates, bonus depreciation, and lower individual income tax rates on dividends and capital gains.
Date: October 2, 2003
Creator: Gravelle, Jane G.
Object Type: Report
System: The UNT Digital Library
Clean Water Act Issues in the 108th Congress (open access)

Clean Water Act Issues in the 108th Congress

In this report several other Clean Water Act issues are likely to receive congressional attention, through oversight hearings and possibly in legislative proposals. Among the topics of interest is whether and how the Administration will revise the current program for restoration of pollution-impaired waters (the Total Maximum Daily Load, or TMDL program), in view of controversy over regulatory changes made during the Clinton Administration and continuing disagreement among states, cities, industry, and environmental advocates about program effectiveness and efficiency.
Date: October 2, 2003
Creator: Copeland, Claudia
Object Type: Report
System: The UNT Digital Library
Commercial Spent Nuclear Fuel Waste Package Misload Analysis (open access)

Commercial Spent Nuclear Fuel Waste Package Misload Analysis

The purpose of this calculation is to estimate the probability of misloading a commercial spent nuclear fuel waste package with a fuel assembly(s) that has a reactivity (i.e., enrichment and/or burnup) outside the waste package design. The waste package designs are based on the expected commercial spent nuclear fuel assemblies and previous analyses (Macheret, P. 2001, Section 4.1 and Table 1). For this calculation, a misloaded waste package is defined as a waste package that has a fuel assembly(s) loaded into it with an enrichment and/or burnup outside the waste package design. An example of this type of misload is a fuel assembly designated for the 21-PWR Control Rod waste package being incorrectly loaded into a 21-PWR Absorber Plate waste package. This constitutes a misloaded 21-PWR Absorber Plate waste package, because the reactivity (i.e., enrichment and/or burnup) of a 21-PWR Control Rod waste package fuel assembly is outside the design of a 21-PWR Absorber Plate waste package. These types of misloads (i.e., fuel assembly with enrichment and/or burnup outside waste package design) are the only types that are evaluated in this calculation. This calculation utilizes information from ''Frequency of SNF Misload for Uncanistered Fuel Waste Package'' (CRWMS M&O 1998) as …
Date: October 2, 2003
Creator: Knudson, J.K.
Object Type: Report
System: The UNT Digital Library
Contract Management: Restructuring GSA's Federal Supply Service and Federal Technology Service (open access)

Contract Management: Restructuring GSA's Federal Supply Service and Federal Technology Service

Testimony issued by the General Accounting Office with an abstract that begins "The General Services Administration's (GSA) Federal Supply Service (FSS) and Federal Technology Service (FTS) play an important role in assisting agencies procure a wide range of products and services. Over the past several years, FSS and FTS purchases have significantly increased, with IT products and services being the primary source of this growth. In April 2002, we identified overlap in FSS' and FTS' IT procurement programs. A management consultant similarly found overlaps in FTS' and FSS' IT sales and marketing functions and contract offerings. To enhance FSS and FTS operational efficiency and effectiveness--in both its IT and non-IT business lines--GSA has undertaken a performance improvement initiative. This testimony focuses on GSA's actions to implement its initiative. It also discusses the importance of enhancing GSA's ability to help agencies strategically purchase products and services."
Date: October 2, 2003
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library