Multiscale Stochastic Simulation and Modeling (open access)

Multiscale Stochastic Simulation and Modeling

Acceleration driven instabilities of fluid mixing layers include the classical cases of Rayleigh-Taylor instability, driven by a steady acceleration and Richtmyer-Meshkov instability, driven by an impulsive acceleration. Our program starts with high resolution methods of numerical simulation of two (or more) distinct fluids, continues with analytic analysis of these solutions, and the derivation of averaged equations. A striking achievement has been the systematic agreement we obtained between simulation and experiment by using a high resolution numerical method and improved physical modeling, with surface tension. Our study is accompanies by analysis using stochastic modeling and averaged equations for the multiphase problem. We have quantified the error and uncertainty using statistical modeling methods.
Date: January 10, 2006
Creator: Glimm, James & Li, Xiaolin
Object Type: Report
System: The UNT Digital Library
FINAL REPORT: DOE-FG03-95ER25250 (open access)

FINAL REPORT: DOE-FG03-95ER25250

The research conducted in this project concerns the geometry of extremal surfaces, embedded minimal surfaces in particular. The methods include geometric analysis, computational simulation, mathematical visualization and software development. Minimal surface research stands at the intersection of partial differential equations, calculus of variations, complex function theory and topology. Advances in this area are often---as is the case with our research---tied to the development and implementation of computational methods and tools of mathematical visualization. Understanding the structure of the space of minimal surfaces has been important in applications from cosmology to structural engineering, as well as other applied areas including polymer physics. The subject has benefited from the discovery of new examples by the use of computation, examples far beyond the range current theoretical construction techniques. Not only are these surfaces important for the understanding of equilibrium morphology via inter-material dividing surfaces, they arise in the study of grain boundaries and dislocations. These same examples are in turn signposts for the further theoretical development in mathematics. This research project has made fundamental advances in the study of equilibrium interfaces. Carrying on the parent project that was based at the University of Massachusetts, we have: Proved the existence of large families of …
Date: January 10, 2006
Creator: Hoffman, David
Object Type: Report
System: The UNT Digital Library
Design and Application of an Electronic Logbook for Space System Integration and Test Operations (open access)

Design and Application of an Electronic Logbook for Space System Integration and Test Operations

In the highly technological aerospace world paper is still widely used to document space system integration and test (I&T) operations. E-Logbook is a new technology designed to substitute the most commonly used paper logbooks in space system I&T, such as the connector mate/demate logbook, the flight hardware and flight software component installation logbook, the material mix record logbook and the electronic ground support equipment validation logbook. It also includes new logbook concepts, such as the shift logbook, which optimizes management oversight and the shift hand-over process, and the configuration logbook, which instantly reports on the global I&T state of the space system before major test events or project reviews. The design of E-Logbook focuses not only on a reliable and efficient relational database, but also on an ergonomic human-computer interactive (HCI) system that can help reduce human error and improve I&T management and oversight overall. E-Logbook has been used for the I&T operation of the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) at the Stanford Linear Accelerator Center (SLAC). More than 41,000 records have been created for the different I&T logbooks, with no data having been corrupted or critically lost. 94% of the operators and 100% of …
Date: October 10, 2006
Creator: Kavelaars, Alicia T. & /SLAC /Stanford U., Dept. Aeronaut. Astronaut.
Object Type: Report
System: The UNT Digital Library
MODIFIED BOROHYDRIDES FOR REVERSIBLE HYDROGEN STORAGE (open access)

MODIFIED BOROHYDRIDES FOR REVERSIBLE HYDROGEN STORAGE

This paper reports the results in the effort to destabilize lithium borohydride for reversible hydrogen storage. A number of metals, metal hydrides, metal chlorides and complex hydrides were selected and evaluated as the destabilization agents for reducing dehydriding temperature and generating dehydriding-rehydriding reversibility. It is found that some additives are effective. The Raman spectroscopic analysis shows the change of B-H binding nature.
Date: May 10, 2006
Creator: Au, Ming
Object Type: Article
System: The UNT Digital Library
Measurement of the B- -> D0K*- Branching Fraction (open access)

Measurement of the B- -> D0K*- Branching Fraction

From a sample of 232 million {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II B Factory in 1999-2004, they measure the B{sup -} {yields} D{sup 0} K*{sup -}(892) decay branching fraction using events where the K*{sup -} is reconstructed in the K{sub S}{sup 0}{pi}{sup -} mode and the D{sup 0} in the K{sup -}{pi}{sup +}, K{sup -}{pi}{sup +}{pi}{sup 0}, and K{sup -}{pi}{sup +}{pi}{sup +}{pi}{sup -} channels: {Beta}(B{sup -} {yields} D{sup 0}K*{sup -}(892)) = (5.29 {+-} 0.30 (stat) {+-} 0.34 (syst)) x 10{sup -4}.
Date: April 10, 2006
Creator: Aubert, B.
Object Type: Report
System: The UNT Digital Library
Measurement of B0bar -> D(*)0 K(*)0bar BranchingFractions (open access)

Measurement of B0bar -> D(*)0 K(*)0bar BranchingFractions

The authors present a study of the decays {bar B}{sup 0} {yields} D{sup (*)0}{bar K}{sup (*)0} using a sample of 226 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 report evidence for the decay of B{sup 0} and {bar B}{sup 0} mesons to the D*{sup 0}K{sub S}{sup 0} final state with an average branching fraction {Beta}({bar B}{sup 0} {yields} D*{sup 0} {bar K}{sup 0}) {triple_bond} {Beta}({bar B}{sup 0} {yields} D*{sup 0} {bar K}{sup 0}) + {Beta}(B{sup 0} {yields} D*{sup 0}K{sup 0})/2 = (3.6 {+-} 1.2 {+-} 0.3) x 10{sup -5}.
Date: April 10, 2006
Creator: Aubert, B.
Object Type: Report
System: The UNT Digital Library
Ion Motion inthe Adiabatic Focuser (open access)

Ion Motion inthe Adiabatic Focuser

In this paper we numerically study the effect of ion motion in an adiabatic focuser, motivated by a recent suggestion that ion motion in an adiabatic focuser might be significant and even preclude operation of the focuser as previously envisioned. It is shown that despite ion motion the adiabatic focuser should work as well as originally envisioned.
Date: June 10, 2006
Creator: Henestroza, E.; Sessler, A. M. & Yu, S. S.
Object Type: Article
System: The UNT Digital Library
Search for the Decay $\tau^- \rightarrow 3\pi^- 2\pi^+2\pi^0 \nu_\tau$ (open access)

Search for the Decay $\tau^- \rightarrow 3\pi^- 2\pi^+2\pi^0 \nu_\tau$

A search for the decay of the {tau} lepton to five charged and two neutral pions is performed using data collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider. The analysis uses 232 fb{sup -1} of data at center-of-mass energies on or near the {Upsilon}(4S) resonance. We observe 10 events with an expected background of 6.5{sub -1.4}{sup +2.0} events. In the absence of a signal, we set the limit on the branching ratio {Beta}({tau}{sup -} {yields} 3{pi}{sup -}2{pi}{sup +}2{pi}{sup 0}{nu}{sub {tau}}) < 3.4 x 10{sup -6} at the 90% confidence level. This is a significant improvement over the previously established limit. In addition, we search for the decay mode {tau}{sup -} {yields} 2{omega}{pi}{sup -}{nu}{sub {tau}}. We observe 1 event with an expected background of 0.4{sub -0.4}{sup +1.0} events and calculate the upper limit {Beta}({tau}{sup -} {yields} 2{omega}{pi}{sup -}{nu}{sub {tau}}) < 5.4 x 10{sup -7} at the 90% confidence level. This is the first upper limit for this mode.
Date: April 10, 2006
Creator: Aubert, B.
Object Type: Report
System: The UNT Digital Library
Pulsar Electrodynamics: a Time-dependent View (open access)

Pulsar Electrodynamics: a Time-dependent View

Pulsar spindown forms a reliable yet enigmatic prototype for the energy loss processes in many astrophysical objects including accretion disks and back holes. In this paper we review the physics of pulsar magnetospheres, concentrating on recent developments in force-free modeling of the magnetospheric structure. In particular, we discuss a new method for solving the equations of time-dependent force-free relativistic MHD in application to pulsars. This method allows to dynamically study the formation of the magnetosphere and its response to perturbations, opening a qualitatively new window on pulsar phenomena. Applications of the method to other magnetized rotators, such as magnetars and accretion disks, are also discussed.
Date: April 10, 2006
Creator: Spitkovsky, Anatoly
Object Type: Article
System: The UNT Digital Library
ACTION CONCENTRATION FOR MIXTURES OF VOLATILE ORGANIC COMPOUNDS (VOC) & METHANE & HYDROGEN (open access)

ACTION CONCENTRATION FOR MIXTURES OF VOLATILE ORGANIC COMPOUNDS (VOC) & METHANE & HYDROGEN

Waste containers may contain volatile organic compounds (VOCs), methane, hydrogen and possibly propane. These constituents may occur individually or in mixtures. Determining if a waste container contains a flammable concentration of flammable gases and vapors (from VOCs) is important to the safety of the handling, repackaging and shipping activities. This report provides the basis for determining the flammability of mixtures of flammable gases and vapors. The concentration of a mixture that is at the lowest flammability limit for that mixture is called the action concentration. The action concentration can be determined using total VOC concentrations or actual concentration of each individual VOC. The concentrations of hydrogen and methane are included with the total VOC or individual VOC concentration to determine the action concentration. Concentrations below this point are not flammable. Waste containers with gas/vapor concentrations at or above the action concentration are considered flammable.
Date: July 10, 2006
Creator: MARUSICH, R.M.
Object Type: Report
System: The UNT Digital Library
Civilian Radioactive Waste Management System Requirements Document (open access)

Civilian Radioactive Waste Management System Requirements Document

The CRD addresses the requirements of Department of Energy (DOE) Order 413.3-Change 1, ''Program and Project Management for the Acquisition of Capital Assets'', by providing the Secretarial Acquisition Executive (Level 0) scope baseline and the Program-level (Level 1) technical baseline. The Secretarial Acquisition Executive approves the Office of Civilian Radioactive Waste Management's (OCRWM) critical decisions and changes against the Level 0 baseline; and in turn, the OCRWM Director approves all changes against the Level 1 baseline. This baseline establishes the top-level technical scope of the CRMWS and its three system elements, as described in section 1.3.2. The organizations responsible for design, development, and operation of system elements described in this document must therefore prepare subordinate project-level documents that are consistent with the CRD. Changes to requirements will be managed in accordance with established change and configuration control procedures. The CRD establishes requirements for the design, development, and operation of the CRWMS. It specifically addresses the top-level governing laws and regulations (e.g., ''Nuclear Waste Policy Act'' (NWPA), 10 Code of Federal Regulations (CFR) Part 63, 10 CFR Part 71, etc.) along with specific policy, performance requirements, interface requirements, and system architecture. The CRD shall be used as a vehicle to incorporate …
Date: May 10, 2006
Creator: Kouts, C.A.
Object Type: Report
System: The UNT Digital Library
Effect of Aggregation on Thermal Conduction in Colloidal Nanofluids (open access)

Effect of Aggregation on Thermal Conduction in Colloidal Nanofluids

Using effective medium theory we demonstrate that the thermal conductivity of nanofluids can be significantly enhanced by the aggregation of nanoparticles into clusters. The enhancement is based purely on conduction and does not require a novel mechanism. Predictions of the effective medium theory are in excellent agreement with detailed numerical calculations on model nanofluids involving fractal clusters and show the importance of cluster morphology on thermal conductivity enhancements.
Date: August 10, 2006
Creator: Prasher, R; Evans, W; Fish, J; Meakin, P; Phelan, P & Keblinski, Pawel
Object Type: Article
System: The UNT Digital Library
Mo-containing tetrahedral amorphous carbon deposited by dualfiltered cathodic vacuum arc with selective pulsed bias voltage (open access)

Mo-containing tetrahedral amorphous carbon deposited by dualfiltered cathodic vacuum arc with selective pulsed bias voltage

Metal-containing tetrahedral amorphous carbon films were produced by dual filtered cathodic vacuum arc (FCVA) plasma sources operated in sequential pulsed mode. A negatively pulsed bias was applied to the substrate only when carbon plasma was generated. Films thickness was measured after deposition by profilometry. Glass slides with silver pads were used as substrate for the of the measurement sheet resistance. The microstructure and composition of the films were characterized by Raman spectroscopy and Rutherford backscattering, respectively. It found that the electrical resistivity decreases with an increase of the Mo content, which can be ascribed to an increase of sp2 content and an increase of the sp2 cluster size.
Date: September 10, 2006
Creator: Pasaja, Nitisak; Sansongsiri, Sakon; Anders, Andre; Vilaithong,Thiraphat & Intasiri, Sawate
Object Type: Article
System: The UNT Digital Library
Smoothing of ultrathin silver films by transition metalseeding (open access)

Smoothing of ultrathin silver films by transition metalseeding

The nucleation and coalescence of silver islands on coated glass was investigated by in-situ measurements of the sheet resistance. Sub-monolayer amounts of transition metals (Nb, Ti, Ni, Cr, Zr, Ta, and Mo) were deposited prior to the deposition of silver. It was found that some, but not all, of the transition metals lead to coalescence of silver at nominally thinner films with smoother topology. The smoothing effect of the transition metal at sub-monolayer thickness can be explained by a thermodynamic model of surface energies.
Date: February 10, 2006
Creator: Anders, Andre; Byon, Eungsun; Kim, Dong-Ho; Fukuda, Kentaro & Lim,Sunnie H.N.
Object Type: Article
System: The UNT Digital Library
RTP as an Optional Service: It's Alive, But Is It Well? (open access)

RTP as an Optional Service: It's Alive, But Is It Well?

Economists have advocated for real-time pricing (RTP) of electricity on the basis of the gains in economic efficiency that would result from charging customers the contemporaneous marginal cost of supplying electricity instead of the average cost. In recent years, RTP has also become the subject of interest in a variety of policy contexts, including integrated resource planning initiatives, ongoing efforts to improve efficiency and reliability in competitive electricity markets, and implementation of default service in states with retail choice. Most experience with RTP has been as an optional service, that is, a self-selecting alternative to the standard utility service. By our count, approximately 70 utilities in the U.S. offered an optional RTP program at some point over the past 20 years. However, many programs are now defunct. In 2003, 47 utilities in the U.S. were still offering an optional RTP program, on either a pilot or permanent basis (see Figure 1). In addition, 10 utilities in states with retail choice currently offer RTP as the default service for large customers that are not under contract with a competitive supplier. Another two utilities have received regulatory approval to do so in the next few years. Although the results of a few …
Date: March 10, 2006
Creator: Goldman, Charles; Barbose, Galen & Neenan, Bernie
Object Type: Article
System: The UNT Digital Library
Final Performance Report on Linear Collider Tracker Simulation and Alignment R&D (open access)

Final Performance Report on Linear Collider Tracker Simulation and Alignment R&D

Progress on alignment system R&D for a Linear Collider detector tracking system is reported, along with progress on physics and detector simulations relevant to the design of a high-precision tracking subdetector.
Date: August 10, 2006
Creator: Riles, John Keith
Object Type: Report
System: The UNT Digital Library
Physical and Numerical Analysis of Extrusion Process for Production of Bimetallic Tubes (open access)

Physical and Numerical Analysis of Extrusion Process for Production of Bimetallic Tubes

Bimetallic tubes are used for very specific applications where one of the two metals provides strength and the other provides specific properties such as aqueous corrosion and carburization, coking resistance, and special electrical and thermal properties. Bimetallic tubes have application in pulp and paper industry for heat-recovery boilers, in the chemical industry for ethylene production, and in the petrochemical industry for deep oil well explorations. Although bimetallic tubes have major applications in energy-intensive industry, they often are not used because of their cost and manufacturing sources in the United States. This project was intended to address both of these issues.
Date: August 10, 2006
Creator: Misiolek, W. Z. & Sikka, V. K.
Object Type: Report
System: The UNT Digital Library
The LLNL Heavy Element Facility -- Facility Management, Authorization Basis, and Readiness Assessment Lessons Learned in the Heavy Element Facility (B251) Transition from Category II Nuclear Facility to Radiological Facility (open access)

The LLNL Heavy Element Facility -- Facility Management, Authorization Basis, and Readiness Assessment Lessons Learned in the Heavy Element Facility (B251) Transition from Category II Nuclear Facility to Radiological Facility

This paper presents Facility Management, Readiness Assessment, and Authorization Basis experience gained and lessons learned during the Heavy Element Facility Risk Reduction Program (RRP). The RRP was tasked with removing contaminated glove boxes, radioactive inventory, and contaminated ventilation systems from the Heavy Element Facility (B251) at Lawrence Livermore National Laboratory (LLNL). The RRP was successful in its goal in April 2005 with the successful downgrade of B251 from a Category II Nuclear Facility to a Radiological Facility. The expertise gained and the lessons learned during the planning and conduct of the RRP included development of unique approaches in work planning/work control (''Expect the unexpected and confirm the expected'') and facility management. These approaches minimized worker dose and resulted in significant safety improvements and operational efficiencies. These lessons learned can help similar operational and management activities at other sites, including facilities restarting operations or new facility startup. B251 was constructed at LLNL to provide research areas for conducting experiments in radiochemistry using transuranic elements. Activities at B251 once included the preparation of tracer sets associated with the underground testing of nuclear devices and basic research devoted to a better understanding of the chemical and nuclear behavior of the transuranic elements. Due …
Date: April 10, 2006
Creator: Mitchell, M.; Anderson, B.; Brown, E. & Gray, L.
Object Type: Article
System: The UNT Digital Library
An Integrated Front-End Readout And Feature Extraction System for the BaBar Drift Chamber (open access)

An Integrated Front-End Readout And Feature Extraction System for the BaBar Drift Chamber

The BABAR experiment has been operating at SLAC's PEP-II asymmetric B-Factory since 1999. The accelerator has achieved more than three times its original design luminosity of 3 x 10{sup 33} cm{sup -2} s{sup -1}, with plans for an additional factor of three in the next two years. To meet the experiment's performance requirements in the face of significantly higher trigger and background rates, the drift chamber's front-end readout system has been redesigned around the Xilinx Spartan 3 FPGA. The new system implements analysis and feature-extraction of digitized waveforms in the front-end, reducing the data bandwidth required by a factor of four.
Date: August 10, 2006
Creator: Zhang, Jinlong
Object Type: Article
System: The UNT Digital Library
The Role of Demand Response in Default Service Pricing (open access)

The Role of Demand Response in Default Service Pricing

Dynamic retail electricity pricing, especially real-time pricing (RTP), has been widely heralded as a panacea for providing much-needed demand response in electricity markets. However, in designing default service for competitive retail markets, demand response often appears to be an afterthought. But that may be changing as states that initiated customer choice in the past 5-7 years reach an important juncture in retail market design. Most states with retail choice established an initial transitional period, during which utilities were required to offer a default or ''standard offer'' generation service, often at a capped or otherwise administratively-determined rate. Many retail choice states have reached, or are nearing, the end of their transitional period and several states have adopted an RTP-type default service for large commercial and industrial (C&I) customers. Are these initiatives motivated by the desire to induce greater demand response, or is RTP being called upon to serve a different role in competitive markets? Surprisingly, we found that in most cases, the primary reason for adopting RTP as the default service was not to encourage demand response, but rather to advance policy objectives related to the development of competitive retail markets. However, we also find that, if efforts are made in …
Date: March 10, 2006
Creator: Barbose, Galen; Goldman, Chuck & Neenan, Bernie
Object Type: Article
System: The UNT Digital Library
The 10,000 Year Plan (open access)

The 10,000 Year Plan

Pallavi Pharkya thinks a lot about the future. Pharkya, a Ph.D. candidate in materials science and engineering, works in the area of corrosion science, predicting how materials will perform over extended periods of time. Her particular focus is a nickel-chromium-molybdenum alloy called C-22, a highly corrosion-resistant metal. Pharkya's aim is to help determine whether containers made from C-22 can be used to store high-energy nuclear waste--for 10,000 years and longer. Pharkya's work is part of a plan by the U.S. Department of Energy to consolidate the country's nuclear waste in a single proposed repository. The proposed repository is in Yucca Mountain located in a remote Nevada desert. Currently about 70,000 metric tons of spent nuclear fuel and high-level radioactive waste are divided between approximately 100 sites around the country. The undertaking, Pharkya emphasizes, is massive. To study just the corrosion aspects of the packaging, Case is collaborating with eight other universities, five national labs and Atomic Energy of Canada Limited. Even with so many players, the study will likely take several years to complete. Heading the entire group is Joe Payer, a professor of materials science and engineering at Case and Pharkya's mentor. ''I came here to have the opportunity …
Date: February 10, 2006
Creator: Srisaro, L.
Object Type: Article
System: The UNT Digital Library
THE 10,000 YEAR PLAN (open access)

THE 10,000 YEAR PLAN

Pharkya, a Ph.D. candidate in materials science and engineering, works in the area of corrosion science, predicting how materials will perform over extended periods of time. Her particular focus is a nickel-chromium-molybdenum alloy called C-22, a highly corrosion-resistant metal. Pharkya's aim is to help determine whether containers made from C-22 can be used to store high-energy nuclear waste--for 10,000 years and longer. Pharkya's work is part of a plan by the U.S. Department of Energy to consolidate the country's nuclear waste in a single proposed repository. The proposed repository is in Yucca Mountain located in a remote Nevada desert. Currently about 70,000 metric tons of spent nuclear fuel and high-level radioactive waste are divided between approximately 100 sites around the country. The undertaking, Pharkya emphasizes, is massive. To study just the corrosion aspects of the packaging, Case is collaborating with eight other universities, five national labs and Atomic Energy of Canada Limited. Even with so many players, the study will likely take several years to complete. Heading the entire group is Joe Payer, a professor of materials science and engineering at Case and Pharkya's mentor. ''I came here to have the opportunity to work with Dr. Payer, an expert in …
Date: February 10, 2006
Creator: Srisuro, L.
Object Type: Article
System: The UNT Digital Library
Natural Analoges as a Check of Predicted Drift Stability at Yucca Mountain, Nevada (open access)

Natural Analoges as a Check of Predicted Drift Stability at Yucca Mountain, Nevada

Calculations made by the U.S. Department of Energy's Yucca Mountain Project as part of the licensing of a proposed geologic repository (in southwestern Nevada) for the disposal of high-level radioactive waste, predict that emplacement tunnels will remain open with little collapse long after ground support has disintegrated. This conclusion includes the effects of anticipated seismic events. Natural analogues cannot provide a quantitative test of this conclusion, but they can provide a reasonableness test by examining the natural and anthropogenic examples of stability of subterranean openings. Available data from a variety of sources, combined with limited observations by the author, show that natural underground openings tend to resist collapse for millions of years and that anthropogenic subterranean openings have remained open from before recorded history through today. This stability is true even in seismically active areas. In fact, the archaeological record is heavily skewed toward preservation of underground structures relative to those found at the surface.
Date: March 10, 2006
Creator: Stuckless, J.
Object Type: Report
System: The UNT Digital Library
Structural Studies of MJ1529, an O6-methylguanine-DNAMethyltransferase (open access)

Structural Studies of MJ1529, an O6-methylguanine-DNAMethyltransferase

The structure of an O{sub 6}-methylguanine methyltransferase from the thermophile Methanococcus jannaschii has been determined using multinuclear multidimensional NMR spectroscopy. The structure is similar to homologues from other organisms that have been determined by crystallography, with some variation in the N-terminal domain. The C-terminal domain is more highly conserved in both sequence and structure. Regions of the protein show broadening reflecting conformational flexibility that is likely related to function.
Date: January 10, 2006
Creator: Roberts, Anne; Pelton, Jeffrey G. & Wemmer, David E.
Object Type: Article
System: The UNT Digital Library