Investigations into the Early Life History of Naturally Spring Chinook Salmon in the Grande Ronde River Basin : Fish Research Project Oregon : Annual Progress Report Project Period 1 September 1997 to 31 August 1998. (open access)

Investigations into the Early Life History of Naturally Spring Chinook Salmon in the Grande Ronde River Basin : Fish Research Project Oregon : Annual Progress Report Project Period 1 September 1997 to 31 August 1998.

We determined migration timing and abundance of juvenile spring chinook salmon from three populations in the Grande Ronde River basin. We estimated 6,716 juvenile chinook salmon left upper rearing areas of the Grande Ronde River from July 1997 to June 1998; approximately 6% of the migrants left in summer, 29% in fall, 2% in winter, and 63% in spring. We estimated 8,763 juvenile chinook salmon left upper rearing areas of Catherine Creek from July 1997 to June 1998; approximately 12% of the migrants left in summer, 37% in fall, 21% in winter, and 29% in spring. We estimated 8,859 juvenile chinook salmon left the Grande Ronde Valley, located below the upper rearing areas in Catherine Creek and the Grande Ronde River, from October 1997 to June 1998; approximately 99% of the migrants left in spring. We estimated 15,738 juvenile chinook salmon left upper rearing areas of the Lostine River from July 1997 to April 1998; approximately 3% of the migrants left in summer, 61% in fall, 2% in winter, and 34% in spring. We estimated 22,754 juvenile spring chinook salmon left the Wallowa Valley, located below the mouth of the Lostine River, from September 1997 to April 1998; approximately 55% …
Date: January 1, 1998
Creator: Keefe, MaryLouise & Tranquilli, J. Vincent
Object Type: Report
System: The UNT Digital Library
Closure Report for Corrective Action Unit 404: Roller Coaster Sewage Lagoons and North Disposal Trench, Tonopah Test Range, Nevada with ROTC 1, Revision 0 (open access)

Closure Report for Corrective Action Unit 404: Roller Coaster Sewage Lagoons and North Disposal Trench, Tonopah Test Range, Nevada with ROTC 1, Revision 0

This Closure Report provides the documentation for closure of the Roller Coaster Sewage Lagoons and North Disposal Trench Comective Action Unit (CAU) 404. CAU 404 consists of the Roller Coaster Sewage Lagoons (Corrective Action Site [CAS] TA-03-O01-TA-RC) and the North Disposal Trench (CAS TA-21-001-TA-RC). The site is located on the Tonopah Test Range, approximately 225 kilometers (km) (140 miles [mi]) northwest ofLas Vegas, Nevada. . The sewage lagoons received ~quid sanitary waste horn the Operation Roller Coaster Man Camp in 1963 and debris from subsequent range and construction cleanup activities. The debris and ordnance was subsequently removed and properly dispos~, however, pesticides were detected in soil samples born the bottom of the lagoons above the U,S. Environmental Protection Agency Region IX Prelimimuy Remediation Goals (EPA 1996). . The North Disposal Trench was excavated in 1963. Debris from the man camp and subsequent range and construction cleanup activities was placed in the trench. Investigation results indicated that no constituents of concern were detected in soil samples collected from the trench. Remedial alternative proposed in the Comctive Action Decision Document (CADD) fm the site was “Covering” (DOE, 1997a). The Nevada Division of”Enviromnental Protection (NDEP)-approved Correction Action Plan (CAP) proposed the “Covering” niethodology …
Date: September 1, 1998
Creator: Kidman, Lynn
Object Type: Report
System: The UNT Digital Library
Atmospheric Photochemistry Studies of Pollutant Emissions from Transportation Vehicles Operating on Alternative Fuels (open access)

Atmospheric Photochemistry Studies of Pollutant Emissions from Transportation Vehicles Operating on Alternative Fuels

This project was undertaken with the goal of improving our ability to predict the changes in urban ozone resulting from the widespread use of alternative fuels in automobiles. This report presents the results in detail.
Date: July 1, 1998
Creator: Jeffries, H.; Sexton, K. & Yu, J.
Object Type: Report
System: The UNT Digital Library
Updated 3-D mountain scale flow model with thermal effects,Milestone Level 4: SP4CKMM4 (open access)

Updated 3-D mountain scale flow model with thermal effects,Milestone Level 4: SP4CKMM4

None
Date: September 30, 1998
Creator: Haukwa, C. & Bodvarsson, G.S.
Object Type: Report
System: The UNT Digital Library
Evaluation of near field rock treatment during constructions (LADSfeature #22) (open access)

Evaluation of near field rock treatment during constructions (LADSfeature #22)

The purpose of this report is to evaluate the effect of near-field rock treatment by injection of reactive material (calcite) above the drift for the purpose of decreasing postclosure drift seepage. The method used for the calculation was a coupled reaction-transport numerical model for gas-water-rock interaction. This includes the mass conservation of heat, liquid and gas for thermohydrological calculations, of aqueous and gaseous species for advective and diffusive transport, and the kinetics of mineral-water reactions.
Date: November 24, 1998
Creator: Sonnenthal, Eric & Spycher, Nicolas
Object Type: Report
System: The UNT Digital Library
Coupled modeling of non-isothermal multiphase flow, solutetransport and reactive chemistry in porous and fractured media: 1. ModelDevelopment and Validation (open access)

Coupled modeling of non-isothermal multiphase flow, solutetransport and reactive chemistry in porous and fractured media: 1. ModelDevelopment and Validation

Coupled modeling of subsurface multiphase fluid and heat flow, solute transport and chemical reactions can be used for the assessment of acid mine drainage remediation, mineral deposition, waste disposal sites, hydrothermal convection, contaminant transport, and groundwater quality. Here they present a numerical simulation model, TOUGHREACT, which considers non-isothermal multi-component chemical transport in both liquid and gas phases. A wide range of subsurface thermo-physical-chemical processes is considered. The model can be applied to one-, two- or three-dimensional porous and fractured media with physical and chemical heterogeneity. The model can accommodate any number of chemical species present in liquid, gas and solid phases. A variety of equilibrium chemical reactions is considered, such as aqueous complexation, gas dissolution/exsolution, cation exchange, and surface complexation. Mineral dissolution/precipitation can proceed either subject to local equilibrium or kinetic conditions. The coupled model employs a sequential iteration approach with reasonable computing efficiency. The development of the governing equations and numerical approach is presented along with the discussion of the model implementation and capabilities. The model is verified for a wide range of subsurface physical and chemical processes. The model is well suited for flow and reactive transport in variably saturated porous and fractured media. In the second of …
Date: September 1, 1998
Creator: Xu, Tianfu & Pruess, Karsten
Object Type: Report
System: The UNT Digital Library
Method of making multilayered titanium ceramic composites (open access)

Method of making multilayered titanium ceramic composites

A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body follwed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet.
Date: August 25, 1998
Creator: Fisher, George T., II; Hansen; Jeffrey, S.; Oden; Laurance, L.; Turner et al.
Object Type: Patent
System: The UNT Digital Library
Numerical analysis of thermal-hydrological conditions in thesingle heater test at Yucca Mountain (open access)

Numerical analysis of thermal-hydrological conditions in thesingle heater test at Yucca Mountain

The Single Heater Test (SHT) is one of two in-situ thermal tests included in the site characterization program for the potential underground nuclear waste repository at Yucca Mountain. The heating phase of the SHT started in August 1996, and was completed in May 1997 after 9 months of heating. The coupled processes in the unsaturated fractured rock mass around the heater were monitored by numerous sensors for thermal, hydrological, mechanical and chemical data. In addition to passive monitoring, active testing of the rock mass moisture content was performed using geophysical methods and air injection testing. The extensive data set available from this test gives a unique opportunity to improve the understanding of the thermal-hydrological situation in the natural setting of the repository rocks. The present paper focuses on the 3-D numerical simulation of the thermal-hydrological processes in the SHT using TOUGH2. In the comparative analysis, they are particularly interested in the accuracy of different fracture-matrix-interaction concepts such as the Effective Continuum (ECM), the Dual Continuum (DKM), and the Multiple Interacting Continua (MINC) method.
Date: August 8, 1998
Creator: Birkholzer, Jens T. & Tsang, Yvonne W.
Object Type: Report
System: The UNT Digital Library
Structural Formation Studies of UV-Catalyzed Gels and Aerogels by Light Scattering (open access)

Structural Formation Studies of UV-Catalyzed Gels and Aerogels by Light Scattering

The skeletal structure of aerogel is determined before, during, and after the gel is formed. Supercritical drying of aerogel largely preserves the pore structure that is determined near the time of gelation. To better understand these gel formation mechanisms we carried out measurements of the time evolution of light scattering in a series of gels prepared without conventional acid or base catalysis. Instead, ultraviolet light was used to catalyze the formation of silica gels made from the hydrolysis of tetraethylorthosilicate and partly prehydrolyzed tetraethylorthosilicate in ethanol. Time evolution of light scattering provides information regarding the rate and geometrical nature of the assembly of the primary silica particles formed in the sol. UV-catalyzed gels show volumetric growth typical of acid-catalyzed gels, except when UV exposure is discontinued at the gel point, where gels then show linear chain formation typical of base-catalyzed gels. Long term UV exposure leads to coarsening of the pore network, a decrease in the clarity of the aerogel, and an increase in the surface area of the aerogel. Additionally, UV exposure up to the gel point leads to increased crystallinity in the final aerogel.
Date: April 1, 1998
Creator: Hunt, Arlon J. & Ayers, Michael R.
Object Type: Article
System: The UNT Digital Library
Pyrite oxidation in saturated and Unsaturated Porous Media Flow: AComparison of alternative mathematical modeling approaches (open access)

Pyrite oxidation in saturated and Unsaturated Porous Media Flow: AComparison of alternative mathematical modeling approaches

Pyrite (FeS{sub 2}) is one of the most common naturally occurring minerals that is present in many subsurface environments. It plays an important role in the genesis of enriched ore deposits through weathering reactions, is the most abundant sulfide mineral in many mine tailings, and is the primary source of acid drainage from mines and waste rock piles. The pyrite oxidation reaction serves as a prototype for oxidative weathering processes with broad significance for geoscientific, engineering, and environmental applications. Mathematical modeling of these processes is extremely challenging because aqueous concentrations of key species vary over an enormous range, oxygen inventory and supply are typically small in comparison to pyrite inventory, and chemical reactions are complex, involving kinetic control and microbial catalysis. We present the mathematical formulation of a general multi-phase advective-diffusive reactive transport model for redox processes. Two alternative implementations were made in the TOUGHREACT and TOUGH2-CHEM simulation codes which use sequential iteration and simultaneous solution, respectively. The simulators are applied to reactive consumption of pyrite in (1) saturated flow of oxidizing water, and (2) saturated-unsaturated flow in which oxygen transport occurs in both aqueous and gas phases. Geochemical evolutions predicted from different process models are compared, and issues of …
Date: February 15, 1998
Creator: Xu, Tianfu; White, Stephen P. & Pruess, Karsten
Object Type: Report
System: The UNT Digital Library
Weir Property Habitat Evaluation: Project Report (open access)

Weir Property Habitat Evaluation: Project Report

A habitat evaluation of the Weir property, an approximately 200-acre in holding of private property within the Little Pend Oreille National Wildlife Refuge (Refuge), was conducted using the Habitat Evaluation Procedures (HEP) methodology. The Weir property consists of two separate parcels, an upper unit of 40 acres and a 160-acre lower unit. Evaluation species were ruffed grouse and white-tailed deer. Life requisites evaluated were available browse for white-tailed deer and winter food and fall-to-spring cover for ruffed grouse. Field data were collected on October 16, 17, and 21, 1997. Approximately 37 acres of the lower 160-acre unit are currently grasslands with no shrub or tree cover, and therefore do not provide suitable ruffed grouse or white-tailed deer cover. They excluded this acreage from the HEP calculations for current conditions. This acreage was included in the HEP calculations for ruffed grouse after future management strategies were factored in. It was not included in projections for white-tailed deer. The entire property was stratified into 6 stands (2 in the upper unit and 4 in the lower unit) for data collection. Data were collected at 10 points, spaced 20 paces (approximately 16 m) apart along one randomly selected transect in each stand, for …
Date: February 1998
Creator: Smith, Maureen
Object Type: Report
System: The UNT Digital Library
DOE SPENT NUCLEAR FUEL DISPOSAL CONTAINER (open access)

DOE SPENT NUCLEAR FUEL DISPOSAL CONTAINER

The DOE Spent Nuclear Fuel Disposal Container (SNF DC) supports the confinement and isolation of waste within the Engineered Barrier System of the Mined Geologic Disposal System (MGDS). Disposal containers are loaded and sealed in the surface waste handling facilities, transferred to the underground through the access mains, and emplaced in emplacement drifts. The DOE Spent Nuclear Fuel Disposal Container provides long term confinement of DOE SNF waste, and withstands the loading, transfer, emplacement, and retrieval loads and environments. The DOE SNF Disposal Containers provide containment of waste for a designated period of time, and limit radionuclide release thereafter. The disposal containers maintain the waste in a designated configuration, withstand maximum handling and rockfall loads, limit the individual waste canister temperatures after emplacement. The disposal containers also limit the introduction of moderator into the disposal container during the criticality control period, resist corrosion in the expected repository environment, and provide complete or limited containment of waste in the event of an accident. Multiple disposal container designs may be needed to accommodate the expected range of DOE Spent Nuclear Fuel. The disposal container will include outer and inner barrier walls and outer and inner barrier lids. Exterior labels will identify the …
Date: June 26, 1998
Creator: Habashi, F.
Object Type: Report
System: The UNT Digital Library
Monitoring and Evaluation of Smolt Migration in the Columbia River Basin : Volume VI : Evaluation of the 2000 Predictions of the Run-Timing of Wild Migrant Chinook Salmon and Steelhead Trout, and Hatchery Sockeye Salmon in the Snake River Basin, and Combined Wild Hatchery Salminids Migrating to Rock Island and McNary Dams using Program RealTime. (open access)

Monitoring and Evaluation of Smolt Migration in the Columbia River Basin : Volume VI : Evaluation of the 2000 Predictions of the Run-Timing of Wild Migrant Chinook Salmon and Steelhead Trout, and Hatchery Sockeye Salmon in the Snake River Basin, and Combined Wild Hatchery Salminids Migrating to Rock Island and McNary Dams using Program RealTime.

Program RealTime provided tracking and forecasting of the 2000 in season outmigration via the internet for stocks of wild PIT-tagged spring/summer chinook salmon. These stocks were ESUs from nineteen release sites above Lower Granite dam, including Bear Valley Creek, Big Creek, Camas Creek (new), Cape Horn Creek, Catherine Creek, Elk Creek, Herd Creek, Imnaha River, Johnson Creek (new), Lake Creek, Loon Creek, Lostine River, Marsh Creek, Minam River, East Fork Salmon River (new), South Fork Salmon River, Secesh River, Sulfur Creek and Valley Creek. Forecasts were also provided for two stocks of hatchery-reared PIT-tagged summer-run sockeye salmon, from Redfish Lake and Alturas Lake (new); for a subpopulation of the PIT-tagged wild Snake River fall subyearling chinook salmon; for all wild Snake River PIT-tagged spring/summer yearling chinook salmon (new) and steelhead trout (new)detected at Lower Granite Dam during the 2000 outmigration. The 2000 RealTime project began making forecasts for combined wild- and hatchery-reared runs-at-large of subyearling and yearling chinook, coho, and sockeye salmon, and steelhead trout migrating to Rock Island and McNary Dams on the mid-Columbia River and the mainstem Columbia River. Due to the new (in 1999-2000) Snake River basin hatchery protocol of releasing unmarked hatchery-reared fish, the RealTime forecasting …
Date: July 1, 1998
Creator: Burgess, Caitlin
Object Type: Report
System: The UNT Digital Library
TITLE III EVALUATION REPORT FOR THE SUBSURFACE LIGHTING SYSTEM (open access)

TITLE III EVALUATION REPORT FOR THE SUBSURFACE LIGHTING SYSTEM

The objective of this evaluation is to provide recommendations to ensure consistency between the technical baseline requirements, baseline design, and the as-constructed Subsurface Lighting System. Recommendations for resolving discrepancies between the as-constructed system, and the technical baseline requirements are included in this report. Cost and Schedule estimates are provided for all recommended modifications. This report does not address items which do not meet current safety or code requirements. These items are identified to the CMO and immediate action is taken to correct the situation. The report does identify safety and code items for which the A/E is recommending improvements. The recommended improvements will exceed the minimum requirements of applicable code and safety guide lines. These recommendations are intended to improve and enhance the operation and maintenance of the facility.
Date: September 9, 1998
Creator: Fernandez, L.J.
Object Type: Report
System: The UNT Digital Library
MINED GEOLOGIC DISPOSAL SYSTEM (MGDS) MONITORING & CONTROL SYSTEMS CENTRALIZATION TECHNICAL REPORT (open access)

MINED GEOLOGIC DISPOSAL SYSTEM (MGDS) MONITORING & CONTROL SYSTEMS CENTRALIZATION TECHNICAL REPORT

The objective of this report is to identify and document Mined Geologic Disposal System (MGDS) requirements for centralized command and control. Additionally, to further develop the MGDS monitoring and control functions. This monitoring and control report provides the following information: (1) Determines the applicable requirements for a monitoring and control system for repository operations and construction (excluding Performance Confirmation). (2) Makes a determination as to whether or not centralized command and control is required.
Date: March 31, 1998
Creator: McGrath, M.J.
Object Type: Report
System: The UNT Digital Library
Beam Comissioning of the PEP-II High Energy Ring (open access)

Beam Comissioning of the PEP-II High Energy Ring

The PEP-II High Energy Ring (HER), a 9 GeV electron storage ring, has been in commissioning since spring 1997. Initial beam commissioning activities focused on systems checkout and commissioning and on determining the behavior of the machine systems at high beam currents. This phase culminated with the accumulation of 0.75 A of stored beam-sufficient to achieve design luminosity--in January 1998 after 3.5 months of beam time. Collisions with the 3 GeV positron beam of the Low Energy Ring (LER) were achieved in Summer of 1998. At high beam currents, collective instabilities have been seen. Since then, commissioning activities for the HER have shifted in focus towards characterization of the machine and a rigorous program to understand the machine and the beam dynamics is presently underway.
Date: November 12, 1998
Creator: Wienands, U.; Anderson, S.; Assmann, R.; Bharadwaj, V.; Cai, Y.; Clendenin, J. et al.
Object Type: Article
System: The UNT Digital Library
Dworshak Dam Impacts Assessment and Fisheries Investigation Project: Kokanee Entrainment Losses at Dworshak Reservoir, 1996 Annual Progress Report. (open access)

Dworshak Dam Impacts Assessment and Fisheries Investigation Project: Kokanee Entrainment Losses at Dworshak Reservoir, 1996 Annual Progress Report.

We used split-beam hydroacoustics to monitor kokanee Oncorhynchus nerka kennerlyi abundance in Dworshak Reservoir from 1995 to 1996 in order to quantify the impacts of water releases from Dworshak Dam. The kokanee population was at a record high level of 1.9 million age-1 and age-2 fish (350 fish/ha) during June 1995. Large discharges of water during July and August of 1995 did not result in major losses of kokanee. Mid-winter flooding in February. March, and April of 1996: however, caused entrainment losses of 90% of all kokanee in the reservoir. The population declined to 140,000 kokanee. High flows during spring runoff used another 50% of the kokanee to be lost, further reducing the population to 71,000 fish (13 fish/ha). Entrainment losses were partially explainable by the distribution of kokanee in the reservoir. During winter, all age-classes of kokanee congregated near the dam making them susceptible to high releases of water. Kokanee appeared to be less susceptible to entrainment during summer and early fall because most kokanee were in other parts of the reservoir: adults were in the upper reservoir staging to spawn, fry were in the upper reservoir having emerged from tributary streams, and juvenile kokanee were spread throughout the …
Date: October 1, 1998
Creator: Maiolie, Melo A. & Elam, Steve
Object Type: Report
System: The UNT Digital Library
Improving the Accuracy of Using Pyranometers to Measure the Clear Sky Global Solar Irradiance (open access)

Improving the Accuracy of Using Pyranometers to Measure the Clear Sky Global Solar Irradiance

Pyranometer users have customarily applied one responsivity value when calculating the global solar irradiance. Usually, the responsivity value is reported by either the manufacturer or a calibration facility. Many pyranometer calibrations, made both at NREL and elsewhere, have shown that the responsivity of a pyranometer changes with the change in solar zenith and azimuth angles. Depending on how well the pyranometer sensor is radiometrically leveled, these changes can exceed +/-5% of the reported responsivity, which means that errors in the calculated global solar irradiance can exceed +/-5% from the nominal values. This paper describes a method to decrease the errors resulting from the change of the solar zenith angle under clear sky conditions. Two responsivity functions, morning and afternoon, were used instead of one responsivity value. The two functions have been chosen because of asymmetry of the morning and afternoon cosine responses demonstrated by some pyranometers.
Date: June 1, 1998
Creator: Reda, I.
Object Type: Report
System: The UNT Digital Library
Development and testing of an information monitoring anddiagnostic system for large commercial buildings (open access)

Development and testing of an information monitoring anddiagnostic system for large commercial buildings

None
Date: August 1, 1998
Creator: Piette, Mary Ann; Gartland, Lisa; Khalsa, Satkartar; Rumsey,Peter; Lock, Lee Eng; Sebald, Anthony et al.
Object Type: Article
System: The UNT Digital Library
Designing an Epithermal Neutron Beam for Boron Neutron CaptureTherapy for the Fusion Reactions 2H(d,n)3He and 3H(d,n)4He (open access)

Designing an Epithermal Neutron Beam for Boron Neutron CaptureTherapy for the Fusion Reactions 2H(d,n)3He and 3H(d,n)4He

None
Date: August 1, 1998
Creator: Verbeke, J. M.; Costes, S. V.; Bleuel, D.; Vujic, J. & Leung, K. N.
Object Type: Article
System: The UNT Digital Library
A Sealed-Accelerator-Tube Neutron Generator for Boron Neutron Capture Therapy Application (open access)

A Sealed-Accelerator-Tube Neutron Generator for Boron Neutron Capture Therapy Application

Radio-frequency (RF) driven ion sources are being developed in Lawrence Berkeley National Laboratory (LBNL) for sealed-accelerator-tube neutron generator applications. By using a 2.5-cm-diameter RF-driven multicusp source and a computer designed 100 keV accelerator column, peak extractable hydrogen current exceeding 1 A from a 3-mm-diameter aperture, together with H{sup +} yields over 94% have been achieved. These experimental findings together with recent moderator design will enable one to develop compact 14 MeV neutron generators based on the D-T fusion reaction. In this new neutron generator, the ion source, the accelerator and the target are all housed in a sealed metal container without pumping. With a 120 keV and 1 A deuteron beam, it is estimated that a treatment time of {approx} 45 minutes is needed for boron neutron capture therapy.
Date: June 1, 1998
Creator: Leung, K. N.; Leung, K. N.; Lee, Y.; Verbeke, J. M.; Vurjic, J.; Williams, M. D. et al.
Object Type: Article
System: The UNT Digital Library
Seepage into drifts in unsaturated fractured rock at YuccaMountain (open access)

Seepage into drifts in unsaturated fractured rock at YuccaMountain

None
Date: August 17, 1998
Creator: Birkholzer, Jens; Li, Guomin; Tsang, Chin-Fu & Tsang, Yvonne
Object Type: Article
System: The UNT Digital Library
Study of the characteristics of the charmonium 3P0 (chi0) state in the reaction p anti-p -> chi0 -> J/psi gamma -> e+- gamma (open access)

Study of the characteristics of the charmonium 3P0 (chi0) state in the reaction p anti-p -> chi0 -> J/psi gamma -> e+- gamma

None
Date: January 1, 1998
Creator: Pellicano, Paolo & U., /Turin
Object Type: Report
System: The UNT Digital Library
Conformal Field Theories: From Old to New (open access)

Conformal Field Theories: From Old to New

In a short review of recent work, we discuss the general problem of constructing the actions of new conformal field theories from old conformal field theories. Such a construction follows when the old conformal field theory admits new conformal stress tensors in its chiral algebra, and it turns out that the new conformal field theory is generically a new spin-two gauge theory. As an example we discuss the new spin-two gauged sigma models which arise in this fashion from the general conformal non-linear sigma model.
Date: February 11, 1998
Creator: Halpern, M. B. & Schwartz, C.
Object Type: Article
System: The UNT Digital Library