Bounds and Estimates for Elastic Constants of Random Polycrystals of Laminates (open access)

Bounds and Estimates for Elastic Constants of Random Polycrystals of Laminates

In order to obtain formulas providing estimates for elastic constants of random polycrystals of laminates, some known rigorous bounds of Peselnick, Meister, and Watt are first simplified. Then, some new self-consistent estimates are formulated based on the resulting analytical structure of these bounds. A numerical study is made, assuming first that the internal structure (i.e., the laminated grain structure) is not known, and then that it is known. The purpose of this aspect of the study is to attempt to quantify the differences in the predictions of properties of the same system being modeled when such internal structure of the composite medium and spatial correlation information is and is not available.
Date: August 25, 2004
Creator: Berger, E. L.
Object Type: Article
System: The UNT Digital Library
Pyrochlore-rich titanate ceramics for the immobilization of plutonium: redox effects on phase equilibria in cerium- and thorium- substituted analogs (open access)

Pyrochlore-rich titanate ceramics for the immobilization of plutonium: redox effects on phase equilibria in cerium- and thorium- substituted analogs

Three compositions representing plutonium-free analogs of a proposed Ca-Ti-Gd-Hf-U-PU oxide ceramic for the immobilization of plutonium were equilibrated at 1 atm, 1350 C over a range of oxygen fugacities between air and that equivalent to the iron-wuestite buffer. The cerium analog replaces Pu on a mole-per-mole basic with Ce; the thorium analog replaces Pu with Th. A third material has 10 wt% Al{sub 2}O{sub 3} added to the cerium analog to encourage the formation of a Hf-analog of, CaHfTi{sub 2}O{sub 7}, zirconolite, which is referred to as hafnolite. The predominant phase produced in each formulation under all conditions is pyrochlore, A{sub 2}T{sub 2}O{sub 7}, where the T site is filled by Ti, and Ca, the lanthanides, Hf, U and Pu are accommodated on the A-site. Other lanthanide and uranium-bearing phases encountered include brannerite (UTi{sub 2}O{sub 6}), hafnolite (CaHfTi{sub 2}O{sub 7}), perovskite (CaTiO{sub 3}) and a calcium-lanthanide aluminotitanate with nominal stoichiometry (Ca,Ln)Ti{sub 2}Al{sub 9}O{sub 19}, where Ln is a lanthanide. The phase compositions show progressive shifts with decreasing oxygen fugacity. All of the phases observed have previously been identified in titanate-based high-level radioactive waste ceramics and demonstrate the flexibility of these ceramics to variations in processing parameters. The main variation is …
Date: May 25, 2000
Creator: Ryerson, F. J. & Ebbinghaus, B.
Object Type: Report
System: The UNT Digital Library
Isospin Breaking and the Chiral Condensate. (open access)

Isospin Breaking and the Chiral Condensate.

With two degenerate quarks, the chiral condensate exhibits a jump as the quark masses pass through zero. I discuss how this single transition splits into two Ising like transitions when the quarks are made non-degenerate. The order parameter is the expectation of the neutral pion field. The transitions represent long distance coherent phenomena occurring without the Dirac operator having vanishingly small eigenvalues.
Date: July 25, 2005
Creator: Creutz, M.
Object Type: Article
System: The UNT Digital Library
Coupled map lattice model of jet breakup (open access)

Coupled map lattice model of jet breakup

An alternative approach is described to evaluate the statistical nature of the breakup of shaped charge liners. Experimental data from ductile and brittle copper jets are analyzed in terms of velocity gradient, deviation of {Delta}V from linearity, R/S analysis, and the Hurst exponent within the coupled map lattice model. One-dimensional simulations containing 600 zones of equal mass and using distinctly different force-displacement curves are generated to simulate ductile and brittle behavior. A particle separates from the stretching jet when an element of material reaches the failure criterion. A simple model of a stretching rod using brittle, semi-brittle, and ductile force-displacement curves is in agreement with the experimental results for the Hurst exponent and the phase portraits and indicates that breakup is a correlated phenomenon.
Date: January 25, 2001
Creator: Minich, R W; Schwartz, A J & Baker, E L
Object Type: Article
System: The UNT Digital Library
Full-Scale Cookoff Model Validation Experiments (open access)

Full-Scale Cookoff Model Validation Experiments

This paper presents the experimental results of the third and final phase of a cookoff model validation effort. In this phase of the work, two generic Heavy Wall Penetrators (HWP) were tested in two heating orientations. Temperature and strain gage data were collected over the entire test period. Predictions for time and temperature of reaction were made prior to release of the live data. Predictions were comparable to the measured values and were highly dependent on the established boundary conditions. Both HWP tests failed at a weld located near the aft closure of the device. More than 90 percent of unreacted explosive was recovered in the end heated experiment and less than 30 percent recovered in the side heated test.
Date: November 25, 2003
Creator: McClelland, M. A.; Rattanapote, M. K.; Heimdahl, E. R.; Erikson, W. E.; Curran, P. O. & Atwood, A. I.
Object Type: Article
System: The UNT Digital Library
Calculating Expectations with Time-Dependent Perturbations in Quantum Monte Carlo (open access)

Calculating Expectations with Time-Dependent Perturbations in Quantum Monte Carlo

None
Date: May 25, 2004
Creator: Kalos, M H & de Saavedra, F A
Object Type: Article
System: The UNT Digital Library
Clean Reliable Water for the 21st Century (Paper#69880) (open access)

Clean Reliable Water for the 21st Century (Paper#69880)

It is well recognized that half the countries in the world will face significant fresh water shortages in the next 20 years, due largely to growing populations and increased agricultural and industrial demands. These shortages will significantly limit economic growth, decrease the quality of life and human health for billions of people, and could potentially lead to violence and conflict over securing scarce supplies of water. These concerns are not limited to the water-poor countries, of course, as many parts of China and the US face similar problems. Such problems can be exacerbated by fluctuating imbalances between need and supply, poor management practices, and pollution. The future is one that will require significant scientific and technological advances in conservation, preservation, and movement of fresh water, as well as in the development of new or alternative supplies. As an example, these issues are discussed in terms of California, and a case study related to the scientific issues associated with a groundwater banking project in Southern California is provided.
Date: February 25, 2003
Creator: Tompson, A. F. B.; Hudson, G. B. & Maxwell, R. M.
Object Type: Article
System: The UNT Digital Library
Groundwater Monitoring Plan for the 216-S-10 Pond and Ditch, Interim Change Notice 1 (open access)

Groundwater Monitoring Plan for the 216-S-10 Pond and Ditch, Interim Change Notice 1

During 2003, the upgradient well 299-W26-7 went dry and one new groundwater monitoring well was installed downgradient (well 299-W26-14) of the 216-S-10 pond and ditch. This ICN updates the groundwater monitoring wells for the 216-S-10 pond and ditch and adds a revised well location map to the plan.
Date: November 25, 2003
Creator: Williams, Bruce A.
Object Type: Report
System: The UNT Digital Library
Candidate Reagents for Dissolution of Hanford Site Tank Sludges-Scoping Studies with Simulants Using Single Reagents and Their Mixtures (open access)

Candidate Reagents for Dissolution of Hanford Site Tank Sludges-Scoping Studies with Simulants Using Single Reagents and Their Mixtures

Chemical agents were investigated for their efficacies in dissolving metal compound phases known to be present in Hanford tank waste sludges. The phases included Fe(OH)3, Cr(OH)3, Al(OH)3, MnO2, and Na2U2O7. In conjunction with laboratory testing, a survey of the technical literature also was performed to identify candidate reagents. The tests were conducted in three campaigns. First, scoping tests investigated individual agents identified in the literature review along with other candidate agents. Based on the scoping test results, follow-up testing was performed to investigate the efficacies of mixed citric/oxalic acids (CITROX) and mixed nitric/oxalic acids (NITROX). Overall, oxalic acid is the most effective single reagent, dissolving all of the solid phases to some extent. However, for MnO2 and Na2U2O7, reprecipitation soon followed dissolution. The MnO2 also oxidized at least two of organic acids tested, oxalic acid and citric acid, as shown by the evolution of gas during the tests with these reagents. The CITROX and NITROX tests failed to show beneficial synergistic effects in dissolving sludge phases. Instead, the findings suggest that the sequential addition of individual pure reagents (e.g., first citric acid to dissolve MnO2 and Na2U2O7 and removal of the solution followed by oxalic acid to dissolve the Fe, …
Date: August 25, 2003
Creator: Sinkov, Serguei I.
Object Type: Report
System: The UNT Digital Library
Actinide Measurements by Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory (open access)

Actinide Measurements by Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory

We report on the development of an accelerator mass spectrometry (AMS) system for the measurement of actinides at Lawrence Livermore National Laboratory. This AMS system is centered on a recently completed heavy isotope beam line that was designed particularly for high sensitivity, robust, high-throughput measurements of actinide concentrations and isotopic ratios. A fast isotope switching capability has been incorporated in the system, allowing flexibility in isotope selection and for the quasi-continuous normalization to a reference isotope spike. Initially, our utilization of the heavy isotope system has concentrated on the measurement of Pu isotopes. Under current operating conditions, background levels equivalent to {approx}1 x 10{sup 5} atoms are observed during routine {sup 239}Pu and {sup 240}Pu measurements. Measurements of samples containing {approx}10{sup 13} {sup 238}U atoms demonstrate that the system provides a {sup 238}U rejection factor during {sup 239}Pu measurements of {approx}10{sup 7}. Measurements of known materials, combined with results from an externally organized inter-comparison program, indicate that our {sup 239}Pu measurements are accurate and precise down to the {micro}Bq level ({approx}10{sup 6} atoms). Recently, we have investigated the performance of our heavy isotope AMS system in measurements of {sup 237}Np and {sup 236}U. Results of these investigations are discussed. The …
Date: September 25, 2003
Creator: Brown, T A; Marchetti, A A; Martinelli, R E; Cox, C C; Knezovich, J P & Hamilton, T F
Object Type: Article
System: The UNT Digital Library
Large-Actuator-Number Horizontal Path Correction of Atmospheric Turbulence utilizing an Interferometric Phase Conjugate Engine (open access)

Large-Actuator-Number Horizontal Path Correction of Atmospheric Turbulence utilizing an Interferometric Phase Conjugate Engine

An adaptive optical system used to correct horizontal beam propagation paths has been demonstrated. This system utilizes an interferometric wave-front sensor and a large-actuator-number MEMS-based spatial light modulator to correct the aberrations incurred by the beam after propagation along the path. Horizontal path correction presents a severe challenge to adaptive optics systems due to the short atmospheric transverse coherence length and the high degree of scintillation incurred by laser propagation along these paths. Unlike wave-front sensors that detect phase gradients, however, the interferometric wave-front sensor measures the wrapped phase directly. Because the system operates with nearly monochromatic light and uses a segmented spatial light modulator, it does not require that the phase be unwrapped to provide a correction and it also does not require a global reconstruction of the wave-front to determine the phase as required by gradient detecting wave-front sensors. As a result, issues with branch points are eliminated. Because the atmospheric probe beam is mixed with a large amplitude reference beam, it can be made to operate in a photon noise limited regime making its performance relatively unaffected by scintillation. The MEMS-based spatial light modulator in the system contains 1024 pixels and is controlled to speeds in excess …
Date: August 25, 2004
Creator: Baker, K. L.; Stappaerts, E. A.; Gavel, D.; Tucker, J.; Silva, D. A.; Wilks, S. C. et al.
Object Type: Article
System: The UNT Digital Library
Sustainable Development in Kazakhastan: Using Oil and Gas Production by-Product Sulfur for Cost-Effective Secondary End-Use Products. (open access)

Sustainable Development in Kazakhastan: Using Oil and Gas Production by-Product Sulfur for Cost-Effective Secondary End-Use Products.

The Republic of Kazakhstan is continuing to develop its extensive petroleum reserves in the Tengiz region of the northeastern part of the Caspian Sea. Large quantities of by-product sulfur are being produced as a result of the removal of hydrogen sulfide from the oil and gas produced in the region. Lack of local markets and economic considerations limit the traditional outlets for by-product sulfur and the buildup of excess sulfur is a becoming a potential economic and environmental liability. Thus, new applications for re-use of by-product sulfur that will benefit regional economies including construction, paving and waste treatment are being developed. One promising application involves the cleanup and treatment of mercury at a Kazakhstan chemical plant. During 19 years of operation at the Pavlodar Khimprom chlor-alkali production facility, over 900 tons of mercury was lost to the soil surrounding and beneath the buildings. The Institute of Metallurgy and Ore Benefication (Almaty) is leading a team to develop and demonstrate a vacuum-assisted thermal process to extract the mercury from the soil and concentrate it as pure, elemental mercury, which will then be treated using the Sulfur Polymer Stabilization/Solidification (SPSS) process. The use of locally produced sulfur will recycle a low-value industrial …
Date: September 25, 2004
Creator: Kalb, P. D.; Vagin, S.; Beall, P. W. & Levintov, B. L.
Object Type: Article
System: The UNT Digital Library
Collinear Splitting, Parton Evolution and the Strange-Quark Asymmetry of the Nucleon in Nnlo Qcd. (open access)

Collinear Splitting, Parton Evolution and the Strange-Quark Asymmetry of the Nucleon in Nnlo Qcd.

We consider the collinear limit of QCD amplitudes at one-loop order, and their factorization properties directly in color space. These results apply to the multiple collinear limit of an arbitrary number of QCD partons, and are a basic ingredient in many higher-order computations. In particular, we discuss the triple collinear limit and its relation to flavor asymmetries in the QCD evolution of parton densities at three loops. As a phenomenological consequence of this new effect, and of the fact that the nucleon has non-vanishing quark valence densities, we study the perturbative generation of a strange-antistrange asymmetry s(x)-{bar s}(x) in the nucleon's sea.
Date: April 25, 2004
Creator: Rodrigo, G.; Catani, S.; de Florian, D. & Vogelsang, W.
Object Type: Article
System: The UNT Digital Library
Coping With Contaminated Sediments and Soils in the Urban Environment. (open access)

Coping With Contaminated Sediments and Soils in the Urban Environment.

Soils and sediments contaminated with toxic organic and inorganic compounds harmful to the environment and to human health are common in the urban environment. We report here on aspects of a program being carried out in the New York/New Jersey Port region to develop methods for processing dredged material from the Port to make products that are safe for introduction to commercial markets. We discuss some of the results of the program in Computational Environmental Science, Laboratory Environmental Science, and Applied Environmental Science and indicate some possible directions for future work. Overall, the program elements integrate the scientific and engineering aspects with regulatory, commercial, urban planning, local governments, and community group interests. Well-developed connections between these components are critical to the ultimate success of efforts to cope with the problems caused by contaminated urban soils and sediments.
Date: May 25, 2004
Creator: Jones, K. W.; Van Der Lelie,D.; Mcguigan, M. & Al., Et
Object Type: Article
System: The UNT Digital Library
Interim Status Groundwater Monitoring Plan for Low-Level Waste Management Areas 1 to 4, RCRA Facilities, Hanford,Washington (open access)

Interim Status Groundwater Monitoring Plan for Low-Level Waste Management Areas 1 to 4, RCRA Facilities, Hanford,Washington

This document describes the monitoring plan to meet the requirements for interim status groundwater monitoring at Hanford Site low-level waste burial grounds as specified by 40 CFR 265, incorporated by reference in WAC 173-303-400. The monitoring will take place at four separate low-level waste management areas in the 200-West and 200-East Areas, in the central part of the site. This plan replaces the previous monitoring plan.
Date: October 25, 2004
Creator: Dresel, P Evan
Object Type: Report
System: The UNT Digital Library
Science Day 2005 Poster Abstracts: Light and Matter (open access)

Science Day 2005 Poster Abstracts: Light and Matter

None
Date: March 25, 2005
Creator: Kline, K M
Object Type: Article
System: The UNT Digital Library
Micro Benchmarking, Performance Assertions and Sensitivity Analysis: A Technique for Developing Adaptive Grid Applications (open access)

Micro Benchmarking, Performance Assertions and Sensitivity Analysis: A Technique for Developing Adaptive Grid Applications

This study presents a technique that can significantly improve the performance of a distributed application by allowing the application to locally adapt to architectural characteristics of distinct resources in a distributed system. Application performance is sensitive to application parameter--system architecture pairings. In a distributed or Grid enabled applciation, a single parameter configuration for the whole application will not always be optimal for every participating resource. In particular, some configurations can significantly degrade performance. Furthermore, the behavior of a system may change during the course of the run. The technique described here provides an automated mechanism for run-time adaptation of application parameters to the local system architecture. Using a simulation of a Monte Carlo physics code, the authors demonstrate that this technique can achieve speedups of 18%-37% on individual resources in a distributed environment.
Date: February 25, 2002
Creator: Corey, I R; Johnson, J R & Vetter, J S
Object Type: Article
System: The UNT Digital Library
Historical Sulfur Dioxide Emissions 1850-2000: Methods and Results (open access)

Historical Sulfur Dioxide Emissions 1850-2000: Methods and Results

A global, self-consistent estimate of sulfur dioxide emissions over the last one and a half century were estimated by using a combination of bottom-up and best available inventory methods including all anthropogenic sources. We find that global sulfur dioxide emissions peaked about 1980 and have generally declined since this time. Emissions were extrapolated to a 1{sup o} x 1{sup o} grid for the time period 1850-2000 at annual resolution with two emission height levels and by season. Emissions are somewhat higher in the recent past in this new work as compared with some comprehensive estimates. This difference is largely due to our use of emissions factors that vary with time to account for sulfur removals from fossil fuels and industrial smelting processes.
Date: January 25, 2004
Creator: Smith, Steven J.; Andres, Robert; Conception , Elvira & Lurz, Joshua
Object Type: Report
System: The UNT Digital Library
Impulse Response Estimation for Spatial Resolution Enhancement in Ultrasonic NDE Imaging (open access)

Impulse Response Estimation for Spatial Resolution Enhancement in Ultrasonic NDE Imaging

This report describes a signal processing algorithm and MATLAB software for improving spatial resolution in ultrasonic nondestructive evaluation (NDE) imaging of materials. Given a measured reflection signal and an associated reference signal, the algorithm produces an optimal least-squares estimate of the impulse response of the material under test. This estimated impulse response, when used in place of the raw reflection signal, enhances the spatial resolution of the ultrasonic measurements by removing distortion caused by the limited-bandwidth transducers and the materials under test. The theory behind the processing algorithms is briefly presented, while the reader is referred to the bibliography for details. The main focus of the report is to describe how to use the MATLAB software. Two processing examples using actual ultrasonic measurements are provided for tutorial purposes.
Date: June 25, 2004
Creator: Clark, G A
Object Type: Report
System: The UNT Digital Library
Ultrasonic Examination of Double-Shell Tank 241-SY-101. Examination Completed March 2004. (open access)

Ultrasonic Examination of Double-Shell Tank 241-SY-101. Examination Completed March 2004.

COGEMA Engineering Corporation (COGEMA), under a contract from CH2M Hill Hanford Group (CH2M Hill), has performed an ultrasonic nondestructive examination of selected portions of Double-Shell Tank 241-SY-101. The purpose of this examination was to provide information that could be used to evaluate the integrity of the wall of the primary tank. The requirements for the ultrasonic examination of Tank 241-SY-101 were to detect, characterize (identify, size, and locate), and record measurements made of any wall thinning, pitting, or cracks that might be present in the wall of the primary tank. Any measurements that exceed the requirements set forth in the Engineering Task Plan (ETP), RPP-17750 (Jensen 2003) and summarized on page 1 of this document, are reported to CH2M Hill and the Pacific Northwest National Laboratory (PNNL) for further evaluation. Under the contract with CH2M Hill, all data is to be recorded on disk and paper copies of all measurements are provided to PNNL for third-party evaluation. PNNL is responsible for preparing a report that describes the results of the COGEMA ultrasonic examinations.
Date: May 25, 2004
Creator: Pardini, Allan F. & Posakony, Gerald J.
Object Type: Report
System: The UNT Digital Library
Macroscopic Superlattices of CdSe Colloidal Nanocrystals: Appearance and Optical Properties (open access)

Macroscopic Superlattices of CdSe Colloidal Nanocrystals: Appearance and Optical Properties

Two and three dimensional assemblies of colloidal nanocrystals (NCs) have been of great interest during recent years [1-3]. While size-dependent optical and electronic properties of isolated particles are particularly important for fundamental research, studies of their ordered assemblies provide a transition path to the engineering of materials and devices for future practical applications. Assemblies of NCs of different materials, such as semiconductors, metals and metal oxides, have been reported in the literature during recent years [4-7]. However, perfect, crystallographic-ordered assemblies of colloidal NCs or colloidal superlattices (SLs) have been observed so far only using transmission (TEM) and scanning electron microscopy (SEM) in a very small scale of a few hundred nanometers, while macroscopic characterization and device application demonstrations have been performed mainly on amorphous, randomly packed powders of NCs [8, 9]. To make SLs available for traditional methods of characterization, they should be obtained in a sufficiently large size. For colloidal NCs soluble in variety of solvents, simple growth from solution seems to be an appropriate choice to produce SLs. In solution, NCs act as large molecules that, as shown previously [1, 8], can form nanoscale ordered assemblies by the classical Frank-Cabrerra mechanism [10] of crystal growth. It is, however, …
Date: March 25, 2004
Creator: Zaitseva, N; Manna, L; Leon, F; Gerion, D; Saw, C & Galli, G
Object Type: Article
System: The UNT Digital Library
An Analysis of Stream Culvert Fish Passage on the Navy Railroad Line between Bremerton and Shelton, Washington (open access)

An Analysis of Stream Culvert Fish Passage on the Navy Railroad Line between Bremerton and Shelton, Washington

The Navy railroad service line runs between Shelton, Bremerton, and Silverdale, and is used by the Navy to transfer freight to its facilities. It is also used by commercial clients to ship service items and bulk cargo for municipalities along portions of the route. Culverts of various size and construction convey streams and stormwater runoff under the railroad line. These allow transfer of water and, in some cases allow for passage of juvenile and adult salmon into waters upstream of the culverts. As part of this project, 21 culverts along a 34-mile reach (Shelton to Bremerton) of this railroad were surveyed to evaluate their function and ability to allow salmon to utilize the streams. The culverts and attached watersheds were evaluated using criteria developed by the Washington Department of Fish and Wildlife to assign a Priority Index (PI) to barriers present on each fish-bearing stream. The PI is a relative numeric rating indicator, assigned using consistent criteria related to the degree of potential habitat gained by removing barriers and improving the function of the watershed. Of the 21 culverts evaluated, five were found to be complete fish-passage barriers and six were found to be partial barriers, primarily to juvenile salmon. …
Date: October 25, 2004
Creator: May, Christopher W.; Miller, Martin C. & Southard, John A.
Object Type: Report
System: The UNT Digital Library
Position Resolution Studies with MSU 32-Fold Segmented HPGe Detector (open access)

Position Resolution Studies with MSU 32-Fold Segmented HPGe Detector

We present position sensitivity measurements obtained with one of the 32-fold segmented HPGe detectors from Michigan State University. These measurements were performed with a collimated beam of {sup 137}Cs gamma rays scattered by 90 degrees. This deposits 374 keV at a given location inside the crystal. A position resolution can be determined over many events by examining the digitally recorded pulse shapes on the 32 electrical contacts. If position resolution is adequate, gamma ray Compton camera imaging may be possible.
Date: October 25, 2001
Creator: Lehner, C E; Vetter, K; Kuhn, A; Schmid, G J; Beckedahl, D A; Blair, J J et al.
Object Type: Article
System: The UNT Digital Library
Simulation of Time-Reversal Processing for Electromagnetic Communication (open access)

Simulation of Time-Reversal Processing for Electromagnetic Communication

Time-reversal processing was simulated for several possible electromagnetic communication channels, including random point scatterers, large plates and a conducting cavity. Communication was from a single transmitting antenna to a receiving array. The effectiveness of time-reversal processing was compared for a single receiver and the array. The aim of these simulations was to determine a communication environment that would give an interesting level of multipath interference and that can be constructed in a laboratory.
Date: July 25, 2003
Creator: Burke, G J & Poggio, A J
Object Type: Report
System: The UNT Digital Library