RadHeat V1 User's Manual (open access)

RadHeat V1 User's Manual

RadHeat is a one dimensional finite difference heat transfer code that can determine the transient temperature evolution of layered targets in pulsed penetrating radiation environments. It makes use of energy dependent opacity and stopping data to model the volumetric deposition of any number of photon or ion spectra each incident at arbitrary angles. Convective and radiative boundary conditions are handled as well as the ability to impose any initial temperature profile. The heat diffusion equation is formulated implicitly to eliminate timestep dependent stability issues. Simulations are, therefore, able to achieve high fidelity during times of thermal activity and greater speed elsewhere. The prototypical physical situation simulated by RadHeat is illustrated. RadHeat was originally written to study the temperature response of tungsten-armored target-facing walls to the pulsed photon and ion radiation emanating from fusion microexplosions in future IFE power plants. RadHeat's implementation is quite general, though, and the code can be applied to a very broad range of problems. Anything from the heating of the Earth's crust on a warm summer day to the temperature rise in a mirror after a laser pulse could potentially be modeled. This manual was written to help new users learn how to run the code …
Date: January 3, 2005
Creator: Abbott, R P
Object Type: Text
System: The UNT Digital Library
Vehicular Storage of Hydrogen in Insulated Pressure Vessels (open access)

Vehicular Storage of Hydrogen in Insulated Pressure Vessels

This paper describes the development of an alternative technology for storing hydrogen fuel onboard automobiles. Insulated pressure vessels are cryogenic-capable pressure vessels that can accept cryogenic liquid fuel, cryogenic compressed gas or compressed gas at ambient temperature. Insulated pressure vessels offer advantages over conventional H{sub 2} storage approaches. Insulated pressure vessels are more compact and require less carbon fiber than GH{sub 2} vessels. They have lower evaporative losses than LH{sub 2} tanks, and are much lighter than metal hydrides. After outlining the advantages of hydrogen fuel and insulated pressure vessels, the paper describes the experimental and analytical work conducted to verify that insulated pressure vessels can be used safely for vehicular H{sub 2} storage. The paper describes tests that have been conducted to evaluate the safety of insulated pressure vessels. Insulated pressure vessels have successfully completed a series of DOT, ISO and SAE certification tests. A draft procedure for insulated pressure vessel certification has been generated to assist in a future commercialization of this technology. An insulated pressure vessel has been installed in a hydrogen fueled truck and it is currently being subjected to extensive testing.
Date: January 3, 2005
Creator: Aceves, S. M.; Berry, G. D.; Martinez-Frias, J. & Espinosa-Loza, F.
Object Type: Article
System: The UNT Digital Library
Supercritical Stability, Transitions, and (Pseudo)tachyons (open access)

Supercritical Stability, Transitions, and (Pseudo)tachyons

Highly supercritical strings (c >> 15) with a time-like linear dilaton provide a large class of solutions to string theory, in which closed string tachyon condensation is under control (and follows the worldsheet renormalization group flow). In this note we analyze the late-time stability of such backgrounds, including transitions between them. The large friction introduced by the rolling dilaton and the rapid decrease of the string coupling suppress the back-reaction of naive instabilities. In particular, although the graviton, dilaton, and other light fields have negative effective mass squared in the linear dilaton background, the decaying string coupling ensures that their condensation does not cause large back-reaction. Similarly, the copious particles produced in transitions between highly supercritical theories do not back-react significantly on the solution. We discuss these features also in a somewhat more general class of time-dependent backgrounds with stable late-time asymptotics.
Date: January 3, 2007
Creator: Aharony, Ofer & Silverstein, Eva
Object Type: Article
System: The UNT Digital Library
Trade and the Americas (open access)

Trade and the Americas

None
Date: January 3, 2003
Creator: Ahearn, Raymond J.
Object Type: Report
System: The UNT Digital Library
Nanoscale Science and Technology for the Development of Environmental Sensors (open access)

Nanoscale Science and Technology for the Development of Environmental Sensors

Under this funding, we proposed to: i) develop a ChemFET sensor platform, ii) develop a ChemDiode sensor platform, iii) synthesize receptor molecules suitable for chemical sensing, iv) study the electrostatic potential changes induced by receptor/target binding on surfaces and v) develop VLSI fabrication approaches for micron-scale chemical sensor devices. The accomplishments under these various thrusts are summarized in this section.
Date: January 3, 2007
Creator: Andres, Ronald; Janes, David; Clifford Kubiak, Clifford & Reifenberger, Ronald
Object Type: Report
System: The UNT Digital Library
NATO and the European Union (open access)

NATO and the European Union

Report which discusses issues related to the North Atlantic Trade Organization (NATO) and the European Union (EU) including the level of involvement of the entities in using political and military actions to defend against terrorism and proliferation, the types of military forces necessary, the role of the EU in crisis management, the appropriateness of decision-making procedures to respond to emerging threats, and the role of other international institutions.
Date: January 3, 2006
Creator: Archick, Kristin & Gallis, Paul E.
Object Type: Report
System: The UNT Digital Library
Branching Fraction Measurements of B+ to rho+ gamma,B0 to rho0 gamma, and B0 to omega gamma (open access)

Branching Fraction Measurements of B+ to rho+ gamma,B0 to rho0 gamma, and B0 to omega gamma

The authors present a study of the decays B{sup +} {yields} {rho}{sup +}{gamma}, B{sup 0} {yields} {rho}{sup 0}{gamma}, and B{sup 0} {yields} {omega}{gamma}. The analysis is based on data containing 347 million B{bar B} events recorded with the BABAR detector at the PEP-II asymmetric B factory. They measure the branching fractions {Beta}(B{sup +} {yields} {rho}{sup +}{gamma}) = (1.10{sub -0.33}{sup +0.37} {+-} 0.09) x 10{sup -6} and {Beta}(B{sup 0} {yields} {rho}{sup 0}{gamma}) = (0.79{sub -0.20}{sup +0.22} {+-} 0.06) x 10{sup -6}, and set a 90% C.L. upper limit {Beta}(B{sup 0} {yields} {omega}{gamma}) < 0.78 x 10{sup -6}. They also measure the isospin-averaged branching fraction {Beta}[B {yields} ({rho}/{omega}){gamma}] = (1.25{sub -0.24}{sup +0.25} {+-} 0.09) x 10{sup -6}, from which they determine |V{sub td}/V{sub ts}| = 0.200{sub -0.020}{sup +0.021} {+-} 0.015, where the first uncertainty is experimental and the second is theoretical.
Date: January 3, 2007
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
Evidence for B- to rho0rho0 Decay and Implications for the CKM Angle alpha (open access)

Evidence for B- to rho0rho0 Decay and Implications for the CKM Angle alpha

The authors search for the decays B{sup 0} {yields} {rho}{sup 0}{rho}{sup 0}, B{sup 0} {yields} {rho}{sup 0} f{sub 0}(980), and B{sup 0} {yields} f{sub 0}(980) f{sub 0}(980) in a sample of about 384 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC. They find evidence for B{sup 0} {yields} {rho}{sup 0}{rho}{sup 0} with 3.5{sigma} significance and measure the branching fraction {Beta} = (1.07 {+-} 0.33 {+-} 0.19) x 10{sup -6} and longitudinal polarization fraction f{sub L} = 0.87 {+-} 0.13 {+-} 0.04, where the first uncertainty is statistical, and the second is systematic. The uncertainty on the CKM unitarity angle {alpha} due to penguin contributions in B {yields} {rho}{rho} decays is 18{sup o} at the 1{sigma} level. They also set upper limits on the B{sup 0} {yields} {rho}{sup 0} f{sub 0}(980) and B{sup 0} {yields} f{sub 0}(980)f{sub 0}(980) decay rates.
Date: January 3, 2007
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
Tecnetium-99 Behavior in Savannah River Site High Level Waste Sludges During Waste Processing (open access)

Tecnetium-99 Behavior in Savannah River Site High Level Waste Sludges During Waste Processing

This paper presents results of a study of the behavior of technetium-99 (Tc-99) during high level waste (HLW) processing operations at Savannah River Site (SRS). Its behavior during HLW processing is important to understand because Tc-99 can fractionate in the waste and appear in both the sludge and the salt tanks at SRS. It can also be soluble in groundwaters and thus is an important radionuclide that may dictate how much waste has to be removed from a tank to prepare it for permanent closure. The HLW processing steps considered in this study are: (1) The initial caustic neutralization of the acidic waste streams generated in the SRS canyons to prepare the waste for storage in the mild steel tanks in the SRS Tank Farm. Waste that is insoluble in caustic precipitates while soluble elements remain in the supernates. At SRS insoluble components are segregated into sludge tanks and soluble components into the salt tanks. (2) The operations in the SRS Tank Farm that wash the sludge in preparation for immobilization for permanent disposal. (3) The sludge immobilization process in the Defense Waste Processing Facility (DWPF) that solidifies the solids into a stable borosilicate glass. The data in this study …
Date: January 3, 2006
Creator: BIBLER, N. E.; Fellinger, T. L. & Hobbs, D. T.
Object Type: Article
System: The UNT Digital Library
Waste Form Qualification Compliance Strategy for Bulk Vitrification (open access)

Waste Form Qualification Compliance Strategy for Bulk Vitrification

The Bulk Vitrification System is being pursued to assist in immobilizing the low-activity tank waste from the 53 million gallons of radioactive waste in the 177 underground storage tanks on the Hanford Site. To demonstrate the effectiveness of the bulk vitrification process, a research and development facility known as the Demonstration Bulk Vitrification System (DBVS) is being built to demonstrate the technology. Specific performance requirements for the final packaged bulk vitrification waste form have been identified. In addition to the specific product-performance requirements, performance targets/goals have been identified that are necessary to qualify the waste form but do not lend themselves to specifications that are easily verified through short-term testing. Collectively, these form the product requirements for the DBVS. This waste-form qualification (WFQ) strategy document outlines the general strategies for achieving and demonstrating compliance with the BVS product requirements. The specific objectives of the WFQ activities are discussed, the bulk vitrification process and product control strategy is outlined, and the test strategy to meet the WFQ objectives is described. The DBVS product performance targets/goals and strategies to address those targets/goals are described. The DBVS product-performance requirements are compared to the Waste Treatment and Immobilization Plant immobilized low-activity waste product specifications. …
Date: January 3, 2005
Creator: Bagaasen, Larry M.; Westsik, Joseph H. & Brouns, Thomas M.
Object Type: Report
System: The UNT Digital Library
Improved Thermophotovoltaic (TPV) Performance Using Dielectric Photon Concentrations (DPC) (open access)

Improved Thermophotovoltaic (TPV) Performance Using Dielectric Photon Concentrations (DPC)

This report presents theoretical and experimental results, which demonstrate the feasibility of a new class of thermophotovoltaic (TPV) energy converters with greatly improved power density and efficiency. Performance improvements are based on the utilization of the enhanced photon concentrations within high refractive index materials. Analysis demonstrates that the maximum achievable photon flux for TPV applications is limited by the lowest index in the photonic cavity, and scales as the minimum refraction index squared, n{sup 2}. Utilization of the increased photon levels within high index materials greatly expands the design space limits of TPV systems, including: a 10x increase in power density, a 50% fractional increase in conversion efficiency, or alternatively reduced radiator temperature requirements to as low as {approx} 1000 F.
Date: January 3, 2003
Creator: Baldasaro, P. F. & Fourspring, P. M.
Object Type: Report
System: The UNT Digital Library
Facile Synthesis of a Crystalline, High-Surface Area SnO2 Aerogel (open access)

Facile Synthesis of a Crystalline, High-Surface Area SnO2 Aerogel

We report the preparation of a novel monolithic SnO{sub 2} aerogel using a straightforward sol-gel technique. TEM and XRD analysis show that the as-prepared material is comprised of interconnected, randomly oriented crystalline (rutile) SnO{sub 2} nanoparticles {approx}3-5 nm in size. As a result, the low-density SnO{sub 2} monolith ({approx}97% porous) exhibits a very high surface area of 383 m{sup 2}/g. /XANES spectroscopy at the Sn M{sub 4,5} edge reveals that the electronic structure of the SnO{sub 2} aerogel is similar to that of tetragonal SnO rather than SnO{sub 2} or {beta}-Sn, and that the undercoordinated surface atoms in the material introduce additional Sn-related electronic states close to the conduction band minimum.
Date: January 3, 2005
Creator: Baumann, T. F.; Kucheyev, S. O.; Gash, A. E. & Satcher, J. H. Jr.
Object Type: Article
System: The UNT Digital Library
Exemptions from Environmental Law for the Department of Defense: Background and Issues for Congress (open access)

Exemptions from Environmental Law for the Department of Defense: Background and Issues for Congress

Over time, Congress has included exemptions in several environmental statutes to ensure that requirements of those statutes would not restrict military training needs to the extent that national security would be compromised. This report discusses these exemptions and congressional disagreement over the need for broader exemptions in the absence of data on the overall impact of environmental requirements on training and readiness.
Date: January 3, 2007
Creator: Bearden, David M.
Object Type: Report
System: The UNT Digital Library
Military Base Closures: Role and Costs of Environmental Cleanup (open access)

Military Base Closures: Role and Costs of Environmental Cleanup

This report explains cleanup requirements for the transfer and reuse of properties on closed military bases, discusses property transfer status and cleanup costs on bases closed in prior rounds, and examines estimates of costs to clean up bases to be closed in the 2005 round to make these properties safe for civilian reuse.
Date: January 3, 2007
Creator: Bearden, David M.
Object Type: Report
System: The UNT Digital Library
National Environmental Education Act of 1990: Overview, Implementation, and Reauthorization Issues (open access)

National Environmental Education Act of 1990: Overview, Implementation, and Reauthorization Issues

None
Date: January 3, 2007
Creator: Bearden, David M.
Object Type: Report
System: The UNT Digital Library
Radioactive Tank Waste from the Past Production of Nuclear Weapons: Background and Issues for Congress (open access)

Radioactive Tank Waste from the Past Production of Nuclear Weapons: Background and Issues for Congress

This report provides background information on the disposal of radioactive tank waste, analyzes the waste disposal authority in P.L. 108-375, discusses the implementation of this authority, and examines relevant issues.
Date: January 3, 2007
Creator: Bearden, David M. & Andrews, Anthony
Object Type: Report
System: The UNT Digital Library
Environmental Protection Agency: FY2007 Appropriations Highlights (open access)

Environmental Protection Agency: FY2007 Appropriations Highlights

This report presents a table detailing EPA appropriations for FY2006 and FY2007. Among individual activities, both the full House and the Senate Appropriations Committee approved decreases and increases throughout EPA's eight appropriations accounts in their respective versions of H.R. 5386, when compared with the President's FY2007 request and the FY2006 appropriation.
Date: January 3, 2007
Creator: Bearden, David M. & Esworthy, Robert
Object Type: Report
System: The UNT Digital Library
Agriculture:  Prospective Issues for Congress (open access)

Agriculture: Prospective Issues for Congress

A number of issues affecting U.S. agriculture could receive attention during the 109th Congress. Some are related to new initiatives or to unfinished legislation from the 108th Congress; others have been the focus of ongoing congressional oversight. Although the current (2002) farm bill (P.L. 107-171) generally does not expire until 2007, the agriculture committees could begin hearings on a new measure as early as 2005. The farm bill spells out the types and levels of benefits provided to producers and landowners under commodity price support and conservation programs, both of which could receive close scrutiny in the coming year as lawmakers seek ways to control federal spending. Other concerns include agroterrorism, food safety, and animal and plant diseases (e.g., “mad cow” disease); interest in multilateral and bilateral trade negotiations; the rising cost of energy on farms; environmental issues; and a number of agricultural marketing matters.
Date: January 3, 2005
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
Animal Agriculture: Selected Issues for Congress (open access)

Animal Agriculture: Selected Issues for Congress

This report is a brief overview of some selected issues related to animal agriculture that are drawn from CRS reports.
Date: January 3, 2007
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
Animal Waste and Hazardous Substances: Current Laws and Legislative Issues (open access)

Animal Waste and Hazardous Substances: Current Laws and Legislative Issues

This report is about the importance of animal identification and its issues.
Date: January 3, 2007
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
The Animal Welfare Act: Background and Selected Legislation (open access)

The Animal Welfare Act: Background and Selected Legislation

This report is on The Animal Welfare Act: Background and Selected Legislation.
Date: January 3, 2007
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
The “Farm Bill” in Brief (open access)

The “Farm Bill” in Brief

Federal farm support, food assistance, agricultural trade, marketing, and rural development policies are governed by a variety of separate laws. Although many of these policies can be and sometimes are modified through freestanding authorizing legislation, or as part of other laws, the omnibus, multi-year farm bill provides an opportunity for policymakers to address agricultural and food issues more comprehensively.
Date: January 3, 2007
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
Farmers' Markets: The USDA Role (open access)

Farmers' Markets: The USDA Role

This report discusses federal programs aimed at promoting farmers’ markets. Policy issues include the extent to which the programs contribute to the markets’ success, and the need if any for additional governmental support.
Date: January 3, 2006
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
Horse Slaughter Prevention Bills and Issues (open access)

Horse Slaughter Prevention Bills and Issues

This report provides an overview of the bills and issues of the Horse Slaughter Prevention Bills.
Date: January 3, 2007
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library