2004 Initial Assessments for the T and TX TY Tank Farm Field Investigation Report (FIR): Numerical Simulations (open access)

2004 Initial Assessments for the T and TX TY Tank Farm Field Investigation Report (FIR): Numerical Simulations

In support of CH2M HILL Hanford Group, Inc.’s (CHG) preparation of a Field Investigative Report (FIR) for the Hanford Site Single-Shell Tank Waste Management Area (WMA) T and TX-TY, a suite of numerical simulations of flow and solute transport was executed using the STOMP code to predict the performance of surface barriers for reducing long-term risks from potential groundwater contamination at the T and TX-TY WMA. The scope and parametric data for these simulations were defined by a modeling data package provided by CHG. This report documents the simulation involving 2-D cross sections through the T Tank and the TX-TY Tank Farm. Eight cases were carried out for the cross sections to simulate the effects of interim barrier, water line leak, inventory distribution, and surface recharge on water flow and the transport of long-lived radionuclides (i.e., technecium-99 and uranium) and chemicals (i.e., nitrate and chromium For simulations with barriers, it is assumed that an interim barrier is in place by the year 2010. It was also assumed that, for all simulations, as part of tank farm closure, a closure barrier was in place by the year 2040. The modeling considers the estimated inventories of contaminants within the vadose zone and …
Date: September 24, 2004
Creator: Zhang, Z. F.; Freedman, Vicky L. & Waichler, Scott R.
Object Type: Report
System: The UNT Digital Library
Advancing the R&D of Mesoscale Nondestructive Characterization (open access)

Advancing the R&D of Mesoscale Nondestructive Characterization

This Strategic Initiative (SI) will advance nondestructive characterization of mesoscale (millimeter-sized) objects-allowing micrometer resolution over the objects' entire volume. X-ray imaging will be developed that allows object characterization with materials that vary widely in composition, density, and geometry.
Date: September 24, 2004
Creator: Martz, H. E., Jr.; Aufderheide, M.; Barty, A.; Jackson, J.; Kallman, J. S.; Kozioziemski, B. et al.
Object Type: Report
System: The UNT Digital Library
Advancing the Technology R&D of Tabletop Mesoscale Nondestructive Characterization (open access)

Advancing the Technology R&D of Tabletop Mesoscale Nondestructive Characterization

This Strategic Initiative (SI) will advance nondestructive characterization of mesoscale (millimeter-sized) objects--allowing micrometer resolution over the objects' entire volume. X-ray imaging will be developed that allows object characterization with materials that vary widely in composition, density, and geometry.
Date: September 24, 2004
Creator: Martz, H. E., Jr.; Aufderheide, M.; Barty, A.; Jackson, J. A.; Kallman, J. S.; Kozioziemski, B. et al.
Object Type: Report
System: The UNT Digital Library
Analysis of the carbon-related 'blue' luminescence in GaN (open access)

Analysis of the carbon-related 'blue' luminescence in GaN

The properties of a broad 2.86 eV photoluminescence band in carbon-doped GaN were studied as a function of C-doping level, temperature, and excitation density. The results are consistent with a C{sub Ga}-C{sub N} deep donor-deep acceptor recombination mechanism as proposed by Seager et al. For GaN:C grown by molecular-beam epitaxy (MBE) the 2.86 eV band is observed in Si co-doped layers exhibiting high n-type conductivity as well as in semi-insulating material. For low excitation density (4 W/cm{sup 2}) the 2.86 eV band intensity decreases as a function of cw-laser exposure time over a period of many minutes. The transient behavior is consistent with a model based on carrier diffusion and charge trapping-induced Coulomb barriers. The temperature dependence of the blue luminescence below 150 K was different for carbon-contaminated GaN grown by metalorganic vapor phase epitaxy (MOVPE) compared to C-doped MBE GaN.
Date: September 24, 2004
Creator: Armitage, R.; Yang, Q. & Weber, E.R.
Object Type: Article
System: The UNT Digital Library
Analytical Method for Measuring Total Protium and Total Deuterium in a Gas Mixture Containing H2, D2, and HD Via Gas Chromatography (open access)

Analytical Method for Measuring Total Protium and Total Deuterium in a Gas Mixture Containing H2, D2, and HD Via Gas Chromatography

A new analytical technique has been developed that measures both total protium (H) and deuterium (D) in a gas mixture containing H2, D2, and HD. This new analytical technique uses a micro gas chromatograph (GC) with two molecular sieve columns. One column uses D2 as the carrier gas and the other uses H2 as the carrier gas. Laboratory tests have shown that when used in this configuration the GC can measure both total protium and total deuterium, each with a sensitivity of less than 20 ppm. This new analytical technique was developed as a result of a request to provide instrumentation to measure the protium and deuterium concentrations at several process points during initial testing of the new hydrogen tritium thermal cycling absorption process columns.
Date: March 24, 2004
Creator: SESSIONS, HENRY
Object Type: Report
System: The UNT Digital Library
ANSI/ANS 8.12, Nuclear Criticality Control and Safety of Plutonium-Uranium Fuel Mixtures Outside Reactors (open access)

ANSI/ANS 8.12, Nuclear Criticality Control and Safety of Plutonium-Uranium Fuel Mixtures Outside Reactors

None
Date: May 24, 2004
Creator: Huang, S T
Object Type: Article
System: The UNT Digital Library
An Appraisal of Coupled Climate Model Simulations (open access)

An Appraisal of Coupled Climate Model Simulations

In 2002, the Program for Climate Model Diagnosis and Intercomparison (PCMDI) proposed the concept for a state-of-the-science appraisal of climate models to be performed approximately every two years. Motivation for this idea arose from the perceived needs of the international modeling groups and the broader climate research community to document progress more frequently than provided by the Intergovernmental Panel on Climate Change (IPCC) Assessment Reports. A committee of external reviewers, which included senior researchers from four leading international modeling centers, supported the concept by stating in its review: ''The panel enthusiastically endorses the suggestion that PCMDI develop an independent appraisal of coupled model performance every 2-3 years. This would provide a useful 'mid-course' evaluation of modeling progress in the context of larger IPCC and national assessment activities, and should include both coupled and single-component model evaluations.''
Date: February 24, 2004
Creator: Sperber, K.; Gleckler, P.; Covey, C.; Taylor, K.; Bader, D.; Phillips, T. et al.
Object Type: Report
System: The UNT Digital Library
APS Performance Summary - Update (open access)

APS Performance Summary - Update

High Energy Density Physics (HEDP) Experiments play an important role in corroborating the improved physics codes that underlie LLNL's Stockpile Stewardship mission. Conducting these experiments, whether on the National Ignition Facility (NIF) or another national facility such as Omega, will require not only improvement in the diagnostics for measuring the experiment, but also detailed knowledge of the as-built target components and assemblies themselves. To assist in this effort, a defined set of well-known reference standards have been built and are being used to quantify the performance of different characterization techniques. Without the critical step of using reference standards for qualifying characterization tools there can be no verification of either commercial or internally-developed characterization techniques and thus there is an uncertainty in the input to the as-built physics codes. In FY03, two reference standards were fabricated and characterized using metrology tools. One of the reference standards was built with a cylindrical geometry and the second reference standard was built with a spherical geometry. The standards were designed for manufacturability, stability, and to provide a range of features that can be measured using NDE methods. Detailed information about these methods has been previously documented.
Date: September 24, 2004
Creator: Gross, J.; Kozioziemski, B.; Waters, A. & Martz, H.
Object Type: Report
System: The UNT Digital Library
Asian Summer Monsoon Intraseasonal Variability in General Circulation Models (open access)

Asian Summer Monsoon Intraseasonal Variability in General Circulation Models

The goals of this report are: (1) Analyze boreal summer Asian monsoon intraseasonal variability general circulation models--How well do the models represent the eastward and northward propagating components of the convection and how well do the models represent the interactive control that the western tropical Pacific rainfall exerts on the rainfall over India and vice-versa? (2) Role of air-sea interactions--prescribed vs. interactive ocean; and (3) Mean monsoon vs. variability.
Date: February 24, 2004
Creator: Sperber, K R & Annamalai, H
Object Type: Report
System: The UNT Digital Library
Axial Pressure Drop Measurements during Pilot-Scale Testing of a Mott Crossflow Filter (open access)

Axial Pressure Drop Measurements during Pilot-Scale Testing of a Mott Crossflow Filter

The Department of Energy selected CSSX as the preferred cesium removal technology for Savannah River Site waste. As a pretreatment step for the CSSX flowsheet, personnel contact the incoming salt solution that contains entrained sludge with MST to adsorb strontium and select actinides. They filter the resulting slurry to remove the sludge and MST. The filtrate receives further treatment to remove cesium in the solvent extraction system. The baseline filtration technology uses a Mott crossflow filter. We conducted pilot-scale crossflow filter testing with simulated SRS high level waste to evaluate the impact of operating parameters on the crossflow filtration process. The tests employed 0.5 micron and 0.1 micron filters. The feed slurries for these tests included simulated sludge plus MST, simulated sludge only, and simulated sludge plus manganese oxide solids. The supernate for these tests consisted of 5.6-6.4 M sodium, average salt solution. During the tests, we measured the axial pressure drop as a function of axial velocity, feed slurry, and insoluble solids concentration. This report documents the axial pressure drop data.
Date: June 24, 2004
Creator: POIRIER, MICHAEL
Object Type: Report
System: The UNT Digital Library
B-factory signals for a warped extra dimension (open access)

B-factory signals for a warped extra dimension

We study predictions for B-physics in a class of models, recently introduced, with a non-supersymmetric warped extra dimension. In these models few ({approx} 3) TeV Kaluza-Klein masses are consistent with electroweak data due to bulk custodial symmetry. Furthermore, there is an analog of GIM mechanism which is violated by the heavy top quark (just as in SM) leading to striking signals at B-factories: (1) New Physics (NP) contributions to {Delta}F = 2 transitions are comparable to SM. This implies that, within this NP framework, the success of the SM unitarity triangle fit is a ''coincidence''. Thus, clean extractions of unitarity angles via e.g. B {yields} {pi}{pi}, {rho}{pi}, {rho}{rho}, DK are likely to be affected, in addition to O(1) deviation from SM prediction in Bs mixing. (2) O(1) deviation from SM predictions for B {yields} X{sub s}{ell}{sup +}{ell}{sup -} in rate as well as in forward-backward and direct CP asymmetry. (3) Large mixing-induced CP asymmetry in radiative B decays, wherein the SM unambiguously predicts very small asymmetries. Also, with KK masses 3 TeV or less, and with anarchic Yukawa masses, contributions to electric dipole moments of the neutron are roughly 20 times larger than the current experimental bound so that this …
Date: August 24, 2004
Creator: Agashe, Kaustubh; Perez, Gilad & Soni, Amarjit
Object Type: Article
System: The UNT Digital Library
Benchmarking optimization software with COPS 3.0. (open access)

Benchmarking optimization software with COPS 3.0.

The authors describe version 3.0 of the COPS set of nonlinearly constrained optimization problems. They have added new problems, as well as streamlined and improved most of the problems. They also provide a comparison of the FILTER, KNITRO, LOQO, MINOS, and SNOPT solvers on these problems.
Date: May 24, 2004
Creator: Dolan, E. D.; More, J. J. & Munson, T. S.
Object Type: Report
System: The UNT Digital Library
Bounds and Estimates for Transport Coefficients of Random and Porous Media with High Contrasts (open access)

Bounds and Estimates for Transport Coefficients of Random and Porous Media with High Contrasts

Bounds on transport coefficients of random polycrystals of laminates are presented, including the well-known Hashin-Shtrikman bounds and some newly formulated bounds involving two formation factors for a two-component porous medium. Some new types of self-consistent estimates are then formulated based on the observed analytical structure both of these bounds and also of earlier self-consistent estimates (of the CPA or coherent potential approximation type). 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 a system being modeled when such organized internal structure is present in the medium but detailed spatial correlation information may or (more commonly) may not be available. Some methods of estimating formation factors from data are also presented and then applied to a high-contrast fluid-permeability data set. Hashin-Shtrikman bounds are found to be very accurate estimates for low contrast heterogeneous media. But formation factor lower bounds are superior estimates for high contrast situations. The new self-consistent estimators also tend to agree better with data than either the bounds or the CPA …
Date: September 24, 2004
Creator: Berger, E. L.
Object Type: Article
System: The UNT Digital Library
Chandra HETG Spectra of SS Cyg and U Gem in Quiescence and Outburst (open access)

Chandra HETG Spectra of SS Cyg and U Gem in Quiescence and Outburst

Chandra HETG spectra of the prototypical dwarf novae SS Cyg and U Gem in quiescence and outburst are presented and discussed. When SS Cyg goes into outburst, it becomes dimmer in hard X-rays and displays a dramatic shift in its relative line strengths, whereas when U Gem goes into outburst, it becomes brighter in hard X-rays and displays only a minor shift in its relative line strengths. In both systems, the emission lines become significantly broader in outburst, signaling the presence of high velocity gas either in Keplerian orbits around the white dwarf or flowing outward from the system.
Date: September 24, 2004
Creator: Mauche, C W; Wheatley, P J; Long, K S; Raymond, J C & Szkody, P
Object Type: Article
System: The UNT Digital Library
Characterization of Functionalized Self-Assembled Monolayers and Surface-Attached Interlocking Molecules Using Near-Edge X-ray Absorption Fine Structure Spectroscopy (open access)

Characterization of Functionalized Self-Assembled Monolayers and Surface-Attached Interlocking Molecules Using Near-Edge X-ray Absorption Fine Structure Spectroscopy

Quantitative knowledge of the fundamental structure and substrate binding, as well as the direct measurement of conformational changes, are essential to the development of self-assembled monolayers (SAMs) and surface-attached interlocking molecules, catenanes and rotaxanes. These monolayers are vital to development of nano-mechanical, molecular electronic, and biological/chemical sensor applications. This dissertation investigates properties of functionalized SAMs in sulfur-gold based adsorbed molecular monolayers using quantitative spectroscopic techniques including near-edge x-ray absorption fine structure spectroscopy (NEXAFS) and x-ray photoelectron spectroscopy (XPS). The stability of the gold-thiolate interface is addressed. A simple model SAM consisting of dodecanethiol adsorbed on Au(111) degrades significantly in less than 24 hours under ambient laboratory air. S 2p and O 1s XPS show the gold-bound thiolates oxidize to sulfinates and sulfonates. A reduction of organic material on the surface and a decrease in order are observed as the layer degrades. The effect of the carboxyl vs. carboxylate functionalization on SAM structure is investigated. Carboxyl-terminated layers consisting of long alkyl-chain thiols vs. thioctic acid with short, sterically separated, alkyl groups are compared and contrasted. NEXAFS shows a conformational change, or chemical switchability, with carboxyl groups tilted over and carboxylate endgroups more upright. Surface-attached loops and simple surface-attached rotaxanes are quantitatively …
Date: March 24, 2004
Creator: Willey, T & Willey, T
Object Type: Thesis or Dissertation
System: The UNT Digital Library
COAL PARTICLE FLOW PATTERNS FOR O{sub 2} ENRICHED, LOW NO{sub x} BURNERS (open access)

COAL PARTICLE FLOW PATTERNS FOR O{sub 2} ENRICHED, LOW NO{sub x} BURNERS

This year we focused on investigating the effect of particulate fines in both the hot flow and cold flow studies. This report summarizes the results of those studies in the hot flow and cold flow geometries. In the hot flow studies, increasing the fines content in the pulverized coal enhances combustion stability producing attached flames that were otherwise detached. NO{sub x} emissions are reduced by up to 50% through flame attachment. For always-attached flames, increasing the fraction of fines had little impact on total NO emissions. In the cold flow studies we found that the presence of the fine particles enhanced the velocity fluctuations of the coarse particles. The presence of coarse particles, however, did not affect the motion of the fine particles.
Date: April 24, 2004
Creator: Curtis, Jennifer Sinclair
Object Type: Report
System: The UNT Digital Library
Colloid-Facilitated Transport of Radionuclides through the Vadose Zone (open access)

Colloid-Facilitated Transport of Radionuclides through the Vadose Zone

This project seeks to improve the basic understanding of the role of colloids in facilitating the transport of contaminants in the vadose zone. We focus on three major thrusts: (1) thermodynamic stability and mobility of colloids formed by reactions of sediments with highly alkaline tank waste solutions, (2) colloid-contaminant interactions, and (3) in situ colloid mobilization and colloid-facilitated contaminant transport occurring in both contaminated and uncontaminated Hanford sediments.
Date: June 24, 2004
Creator: Flury, Markus; Harsh, James B.; Zachara, John M.; McCarthy, John F. & Lichtner, Peter C.
Object Type: Report
System: The UNT Digital Library
Comparison of Plasma Parameters Between QH and ELMing Phases of the Same Discharges (open access)

Comparison of Plasma Parameters Between QH and ELMing Phases of the Same Discharges

H-mode confinement is observed for many energy confinement times without edge localized modes (ELMs) in QH (quiescent high-confinement)-mode discharges in DIII-D. To find critical differences between ELMing and QH modes we compared electron temperature (T{sub e}), density (n{sub e}), and ion temperature (T{sub i}), in the pedestal and scrape-off layer (SOL) for a group of discharges. We also compared the electron pressures P{sub ped}, and maximum pressure gradients P{sub e,ped,max grad} because of their importance in confinement and stability. Experimental results show that the core line averaged density, median T{sub e} (pedestal), SOL T{sub e}, and T{sub e} pedestal width, and SOL T{sub i} are nearly the same in QH mode as that during ELMs. The n{sub e} (average pedestal), n{sub e} pedestal width, P{sub ped}, and P{sub e,ped,max grad} are similar to corresponding values in QH mode and at various times between ELMs. However, the pedestal T{sub i} is 1.6 times higher in QH mode than during ELMing.
Date: May 24, 2004
Creator: Lasnier, C.; West, W.; Burrell, K.; deGrassie, J.; Doyle, E. & Osborne, T.
Object Type: Article
System: The UNT Digital Library
A Comprehensive Study of Fracture Patterns and Densities in The Geysers Geothermal Reservoir Using Microearthquake Shear-Wave Splitting Tomography (open access)

A Comprehensive Study of Fracture Patterns and Densities in The Geysers Geothermal Reservoir Using Microearthquake Shear-Wave Splitting Tomography

In this project we developed a method for using seismic S-wave data to map the patterns and densities of sub-surface fractures in the NW Geysers Geothermal Field/ (1) This project adds to both the general methods needed to characterize the geothermal production fractures that supply steam for power generation and to the specific knowledge of these in the Geysers area. (2)By locating zones of high fracture density it will be possible to reduce the cost of geothermal power development with the targeting of high production geothermal wells. (3) The results of the project having been transferred to both US based and international geothermal research and exploration agencies and concerns by several published papers and meeting presentations, and through the distribution of the data handling and other software codes we developed.
Date: February 24, 2004
Creator: Malin, Peter E.; Shalev, Eylon; Lou, Min; Simiyu, Silas M.; Stroujkova, Anastasia & McCausland, Windy
Object Type: Report
System: The UNT Digital Library
CONCEPTS FOR CAPACITIVELY RF-SHIELDED BELLOWS IN CRYOGENIC STRUCTURES. (open access)

CONCEPTS FOR CAPACITIVELY RF-SHIELDED BELLOWS IN CRYOGENIC STRUCTURES.

Bellows are frequently required in accelerators and colliders. Usually RF-shields with spring fingers are employed to screen the bellows. The lack of accessibility in cryogenic systems can be a problem and asks for alternate solutions to eliminate possible overheating, sparking, etc that occurred in intensive beams. This note addresses an alternate kind of RF shield, which uses capacitive contact instead of mechanical contact. The analysis, as well as numerical example of a superconducting cavity structure, shows that the capacitive RF shield satisfies the impedance requirements of both beam and HOMs. The capability of thermal isolation is also analyzed.
Date: March 24, 2004
Creator: ZHAO,Y. HAHN,H.
Object Type: Report
System: The UNT Digital Library
Corrosion Evaluation of Aluminum Alloys in Deionized Water (open access)

Corrosion Evaluation of Aluminum Alloys in Deionized Water

Spent nuclear fuels from foreign and domestic research and test reactors being returned to SRS are now stored with other nuclear materials in the L-basin at the Savannah River Site (SRS). Recent efforts have consolidated the fuel storage systems and L-basin has become the SRS site for water storage of spent nuclear fuels. Corrosion surveillance of coupons in this basin is being performed to provide assurance of safe storage of spent fuel. This paper describes the highlights of recent studies on these aluminum coupons after immersion for more than 7 years in L-basin. Selected coupons were metallurgically characterized to establish the existence of general corrosion and pitting. Pitting was observed on galvanically coupled samples and also on intentionally creviced coupons, thus demonstrating that localized concentration cells were formed during the exposure period. In these cases, the susceptibility to pitting was not attributed to aggressive basin water chemistry but to local condition s (crevices and galvanic coupling) that allowed the development of oxygen and/or metal ion concentration cells that produced locally aggressive waters. General corrosion was also observed on some of the coupons that had not been treated to enhance the protective oxide prior to exposure in the basin water. These …
Date: September 24, 2004
Creator: Vormelker, Philip R. & Duncan, Andrew J.
Object Type: Article
System: The UNT Digital Library
Data Structures and Algorithms for Graph Based Remote Sensed Image Content Storage and Retrieval (open access)

Data Structures and Algorithms for Graph Based Remote Sensed Image Content Storage and Retrieval

The Image Content Engine (ICE) project at Lawrence Livermore National Laboratory (LLNL) extracts, stores and allows queries of image content on multiple levels. ICE is designed for multiple application domains. The domain explored in this work is aerial and satellite surveillance imagery. The highest level of semantic information used in ICE is graph based. After objects are detected and classified, they are grouped based in their interrelations. The graph representing a locally related set of objects is called a 'graphlet'. Graphlets are interconnected into a larger graph which covers an entire set of images. Queries based on graph properties are notoriously difficult due the inherent complexity of the graph isomorphism and sub-graph isomorphism problems. ICE exploits limitations in graph and query structure and uses a set of auxiliary data structures to quickly process a useful set of graph based queries. These queries could not be processed using semantically lower level (tile and object based) queries.
Date: June 24, 2004
Creator: Grant, C W
Object Type: Article
System: The UNT Digital Library
Defining and Testing the Influence of Servo System Response on Machine Tool Compliance (open access)

Defining and Testing the Influence of Servo System Response on Machine Tool Compliance

Compliance can be defined as the measurement of displacement per unit of force applied e.g. nano-meters per Newton (m/N). Compliance is the reciprocal of stiffness. High stiffness means low compliance and visa versa. It is an important factor in machine tool characteristics because it reflects the ability of the machine axis to maintain a desired position as it encounters a force or torque. Static compliance is a measurement made with a constant force applied e.g. the average depth of cut. Dynamic compliance is a measurement made as a function of frequency, e.g. a fast too servo (FTS) that applies a varying cutting force or load, interrupted cuts and external disturbances such as ground vibrations or air conditioning induced forces on the machine. Compliance can be defined for both a linear and rotary axis of a machine tool. However, to properly define compliance for a rotary axis, the axis must allow a commanded angular position. Note that this excludes velocity only axes. In this paper, several factors are discussed that affect compliance but emphasis is placed on how the machine servo system plays a key role in compliance at low to mid frequency regions. The paper discusses several techniques for measuring …
Date: March 24, 2004
Creator: Hopkins, D J
Object Type: Article
System: The UNT Digital Library
Deformation of Single Crystal Molybdenum at High Pressure (open access)

Deformation of Single Crystal Molybdenum at High Pressure

Single crystal samples of micron dimensions oriented in the [001] direction were shortened 10 to 40% in uniaxial compression with superposed hydrostatic pressure to begin investigation of how the onset of yielding evolves with pressure. A testing machine based on opposed anvil geometry with precision pneumatic control of the applied force and capability to measure sub micron displacements was developed to produce shape changing deformation at pressure. The experiments extend observations of pressure dependent deformation to {approx}5Gpa at shortening rates of {approx}2*10{sup -4}. Samples have been recovered for post run characterization and analysis to determine if deformation mechanisms are altered by pressure. Experiments under hydrostatic pressure provide insight into the nature of materials under extreme conditions, and also provide a means for altering deformation behavior in a controlled fashion. The approach has a long history demonstrating that pressure enhances ductility in general, and produces enhanced hardening relative to that expected from normal cold work in the BCC metals Mo, Ta and Nb{sup 2}. The pressure hardening is in excess of that predicted from the measured increase in shear modulus at pressure, and therefore is likely due to a dislocation mechanism, such as suppression of kink pair formation or the interaction …
Date: February 24, 2004
Creator: Bonner, B P; Aracne, C; Farber, D L; Boro, C O & Lassila, D H
Object Type: Report
System: The UNT Digital Library