Resource Type

Degree Department

Applied environmental technology development at the Savannah River Site: A retrospective on the last half of the 20th century (open access)

Applied environmental technology development at the Savannah River Site: A retrospective on the last half of the 20th century

Fifty years ago, the Savannah River Site (SRS) was built to produce nuclear materials. These operations impacted air, soil, groundwater, ecology and the local environment. Throughout its history, SRS has addressed these contamination issues directly and has maintained a strong commitment to environmental stewardship. The site boasts many environmental firsts. Notably, SRS was the first major DOE facility to perform a baseline ecological assessment. This pioneering effort, by Ruth Patrick and the Philadelphia Academy of Sciences, was performed during SRS planning and construction in the early 1950's. This unique early example sets the stage for subsequent efforts. Since that time, the scientists and engineers at SRS have proactively identified environmental problems as they occurred and have skillfully developed elegant and efficient solutions.
Date: March 13, 2000
Creator: Looney, B. B.
System: The UNT Digital Library
Cloud-Resolving Model Intercomparison with the ARM Summer 1997 IOP Data (open access)

Cloud-Resolving Model Intercomparison with the ARM Summer 1997 IOP Data

The Atmospheric Radiation Measurement (ARM) Program's Single Column Model (SCM) working group conducted its intercomparison study of midlatitude summertime continental convection using the July 1995 Intensive Operational Period (IOP) data set (Ghan et al. 2000). Only one cloud-resolving model (CRM) participated in the study. On the other hand, several CRMs participated in the GEWEX (Global Energy and Water-cycle Experiment) Cloud System Study (GCSS) Working Group 4's intercomparison study of tropical deep convection (Krueger and Lazarus 1998; Redelsperger et al. 2000). Both groups decided to have a joint intercomparison project to maximize the resources and advance our understanding of midlatitude continental convection. This joint project compares the cloud-resolving and single-column simulations of summertime continental cumulus convection observed at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site during the ARM Summer 1997 IOP. This paper reports the findings and results of cloud-resolving simulations, while Cederwall et al. (2000) reports the SCM part of the project. Seven CRMs are participating in this project.
Date: March 13, 2000
Creator: Xu, K. M.; Johnson, D. E.; Tao, W. K.; Krueger, S. K.; Khairoutdinov, M.; Randall, D. A. et al.
System: The UNT Digital Library
Comprehensive testing of Nedwind 12-Meter wind turbine blades at NREL (open access)

Comprehensive testing of Nedwind 12-Meter wind turbine blades at NREL

This paper describes the structural testing of two NedWind 25 12-m blades at the National Renewable Energy Laboratory (NREL). The tests were conducted under the Standards, Measurement and Testing (SMT) Program in conjunction with tests conducted by four European laboratories to develop a common database of blade testing methods. All of the laboratories tested duplicate copies of blades taken from series production. Blade properties, including weight, center of gravity, natural frequencies, stiffness, and damping, were determined. Static load tests were performed at 110% of the extreme design load for strain verification. NREL performed single-axis and two-axis fatigue tests using business-as-usual testing practices. The single-axis test combined equivalent life loading for the edge and flap spectra into a single resultant load. The two-axis test applied the edge and flap components independently at a phase angle of 90{degree}. Damage areas were observed at (1) the trailing edge, which cracked near the maximum chord; (2) between the steel root collar and the composite, where circumferential cracking was noted; and (3) along the top of the spar between the 2,500-mm and 4,200-mm stations, where a notable increase in acoustic emissions was detected. NREL observed that the onset of damage occurred earlier in the single-axis …
Date: March 13, 2000
Creator: Larwood, S. & Musial, W.
System: The UNT Digital Library
Demand Activated Manufacturing Architecture (DAMA) model for supply chain collaboration (open access)

Demand Activated Manufacturing Architecture (DAMA) model for supply chain collaboration

The Demand Activated Manufacturing Architecture (DAMA) project during the last five years of work with the U.S. Integrated Textile Complex (retail, apparel, textile, and fiber sectors) has developed an inter-enterprise architecture and collaborative model for supply chains. This model will enable improved collaborative business across any supply chain. The DAMA Model for Supply Chain Collaboration is a high-level model for collaboration to achieve Demand Activated Manufacturing. The five major elements of the architecture to support collaboration are (1) activity or process, (2) information, (3) application, (4) data, and (5) infrastructure. These five elements are tied to the application of the DAMA architecture to three phases of collaboration - prepare, pilot, and scale. There are six collaborative activities that may be employed in this model: (1) Develop Business Planning Agreements, (2) Define Products, (3) Forecast and Plan Capacity Commitments, (4) Schedule Product and Product Delivery, (5) Expedite Production and Delivery Exceptions, and (6) Populate Supply Chain Utility. The Supply Chain Utility is a set of applications implemented to support collaborative product definition, forecast visibility, planning, scheduling, and execution. The DAMA architecture and model will be presented along with the process for implementing this DAMA model.
Date: March 13, 2000
Creator: CHAPMAN,LEON D. & PETERSEN,MARJORIE B.
System: The UNT Digital Library
Determining equivalent damage loading for full-scale wind turbine blade fatigue tests (open access)

Determining equivalent damage loading for full-scale wind turbine blade fatigue tests

This paper describes a simplified method for converting wind turbine rotor design loads into equivalent-damage, constant-amplitude loads and load ratios for both flap and lead-lag directions. It is an iterative method that was developed at the National Renewable Energy Laboratory (NREL) using Palmgren-Miner's linear damage principles. The general method is unique because it does not presume that any information about the materials or blade structural properties is precisely known. According to this method, the loads are never converted to stresses. Instead, a family of M-N curves (moment vs. cycles) is defined with reasonable boundaries for load-amplitude and slope. An optimization program iterates and converges on the constant amplitude test load and load ratio that minimizes the sensitivity to the range of M-N curves for each blade section. The authors constrained the general method to match the NedWind 25 design condition for the Standards, Measurements, and Testing (SMT) blade testing pro gram. SMT participants agreed to use the fixed S-N slope of m = 10 from the original design to produce consistent test-loads among the laboratories. Unconstrained, the general method suggests that slightly higher test loads should be used for the NedWind 25 blade design spectrum. NedWind 25 blade test loads …
Date: March 13, 2000
Creator: Freebury, G. & Musial, W.
System: The UNT Digital Library
Dual-rod Yb: YAG laser for high-power and high-brightness applications (open access)

Dual-rod Yb: YAG laser for high-power and high-brightness applications

The authors describe a diode-pumped Yb:YAG laser producing 1,080 W cw with 27.5% optical-optical efficiency and 532 W Q-switched with M{sup 2} = 2.2 and 17% optical-optical efficiency. The laser uses two composite Yb:YAG rods separated by a 90 degree quartz rotator for bifocusing compensation. A microlensed diode array end-pumps each rod using a hollow lens duct for pump delivery. By changing resonator parameters, they can adjust the fundamental mode size and the output beam quality. Using a flattened gaussian intensity profile to calculate the mode fill efficiency and clipping losses, the authors compare experimental data to modeled output power vs beam quality.
Date: March 13, 2000
Creator: Honea, E. C.; Beach, R.; Mitchell, S. C.; Skidmore, J. A.; Emanuel, M. A.; Sutton, S. B. et al.
System: The UNT Digital Library
Introduction to the Theory and Analysis of Resolved (and Unresolved) Neutron Resonances via SAMMY (open access)

Introduction to the Theory and Analysis of Resolved (and Unresolved) Neutron Resonances via SAMMY

Neutron cross-section data are important for two purposes: First, they provide insight into the nature of matter, increasing our understanding of fundamental physics. Second, they are needed for practical applications (e.g., for calculating when and how a reactor will become critical, or how much shielding is needed for storage of nuclear materials, or for medical applications). Neutron cross section data in the resolved-resonance region are generally obtained by time-of-flight experiments, which must be carefully analyzed if they are to be properly understood and utilized. In this report, important features of the analysis process are discussed, with emphasis on the particular techniques used in the analysis code SAMMY. Other features of the code are also described; these include such topics as calculation of group cross sections (including covariance matrices), generation and fitting of integral quantities, and extensions into the unresolved-resonance region and higher-energy regions.
Date: March 13, 2000
Creator: Larson, N.
System: The UNT Digital Library
Monitoring the Ocean Acoustic Environment: A Model-Based Detection Approach (open access)

Monitoring the Ocean Acoustic Environment: A Model-Based Detection Approach

A model-based approach is applied in the development of a processor designed to passively monitor an ocean acoustic environment along with its associated variations. The technique employs an adaptive, model-based processor embedded in a sequential likelihood detection scheme. The trade-off between state-based and innovations-based monitor designs is discussed, conceptually. The underlying theory for the innovations-based design is briefly developed and applied to a simulated data set.
Date: March 13, 2000
Creator: Candy, J. V. & Sullivan, E. J.
System: The UNT Digital Library
Security issues at the Department of Energy and records management (open access)

Security issues at the Department of Energy and records management

In order to discuss the connection between security issues within the Department of Energy and records management, the author covers a bit of security history and talks about what she calls ``the Amazing Project''. Initiated in late May 1999, it was to be a tri-laboratory (Lawrence Livermore National Laboratory of Livermore, California, Los Alamos National Laboratory of Los Alamos, New Mexico, and Sandia National Laboratories of Albuquerque, New Mexico, and Livermore, California) project. The team that formed was tasked to develop the best set of security solutions that still enabled weapon mission work to get done and the security solutions were to be the same set for everyone. The amazing project was called ''The Integrated Security Management Project'', or ''ISecM' for short. She'll describe why she thinks this project was so amazing and what it accomplished. There's a bit of sad news about the project, but then she'll move onto discuss what was learned at Sandia as a result of the project and what they're currently doing in records management.
Date: March 13, 2000
Creator: NUSBAUM,ANNA W.
System: The UNT Digital Library
Using Arrested Solid-Solid Multiphase Reactions in Geological Materials to Deduce the Rate of Crustal Uplift (open access)

Using Arrested Solid-Solid Multiphase Reactions in Geological Materials to Deduce the Rate of Crustal Uplift

The history geological terrains experience can be traced as a series of temperature and pressure changes. Each change drives the system toward a new state of thermodynamic equilibrium. The resultant overprinted rock fabrics, textures and chemical heterogeneities can be difficult to interpret. However, if carefully chosen, features from the scale of kilometers to nanometers can be used to reconstruct the history of mountain systems. Uplift of the Sri Lankan Central Highlands was rapid enough to preserve well-developed symplectite textures, some of which represent arrested solid-state diffusion-controlled reactions of garnet + O{sub 2} to form orthopyroxene + plagioclase + magnetite, as the rocks were exhumed from over 30 km in the earth's crust. Our objective has been to determine the reaction mechanisms responsible for symplectite development, and to establish the time interval over which these reactions occurred, to constrain the rate of mountain uplift. Considering that the most rapid mechanism is solid state grain-boundary diffusion of oxygen, the reaction time can be constrained by bounding the rate of oxygen supply to the reaction site. The solid state grain boundary diffusion rate of oxygen has been inferred to be ca. 10{sup -14}m{sup 2}-sec (Farver and Yund, 1991), but is sensitive to inferred …
Date: March 13, 2000
Creator: Glassley, W.E. & Meike, A.
System: The UNT Digital Library
Beam Simulations for IRE and Driver - Status and Strategy (open access)

Beam Simulations for IRE and Driver - Status and Strategy

The methods and codes employed in the U.S. Heavy Ion Fusion program to simulate the beams in an Integrated Research Experiments (IRE) facility and a fusion driver are presented in overview. A new family of models incorporating accelerating module impedance, multi-beam, and self-magnetic effects is described, and initial WARP3d particle simulations of beams using these models are presented. Finally, plans for streamlining the machine-design simulation sequence, and for simulating beam dynamics from the source to the target in a consistent and comprehensive manner, are described.
Date: March 13, 2001
Creator: Friedman, A; Grote, D P & Lee, E P
System: The UNT Digital Library
["A Question of Loyalty" article, March 13, 2001] (open access)

["A Question of Loyalty" article, March 13, 2001]

An article, written by Chris Bull for the LGBT magazine "The Advocate", that covers the Republican Unity Coalition, Log Cabin Republicans, and their members' responses to the new Bush administration. On the second page is an advertisement for a new movie.
Date: March 13, 2001
Creator: Bull, Chris
System: The UNT Digital Library
16th National Conference of Black Physics Students - Physics: Science That Unlocks the Secrets of Nature (open access)

16th National Conference of Black Physics Students - Physics: Science That Unlocks the Secrets of Nature

16th National Conference of Black Physics Students - The agenda and its report.
Date: March 13, 2002
Creator: unknown
System: The UNT Digital Library
Determination of Constraint-Modified J-R Curves for Carbon Steel Storage Tanks (open access)

Determination of Constraint-Modified J-R Curves for Carbon Steel Storage Tanks

The fracture toughness testing of A285 carbon steel storage tank material was carried out. A series of single edge-notched bend (SENB) specimens with various constraint levels were used. The variation of crack tip constraint was achieved by changing the ratio of the initial notch length to the specimen depth. The test data show that the J-R curves are specimen-dependent, which is known as the constraint effect. A two-parameter fracture methodology is adopted to construct a constraint-modified J-R curve, which is a function of the constraint parameter, A2, while J remains the loading parameter. This additional fracture parameter is derived from a closed form solution and can be extracted from the finite element analysis for a specific crack configuration. Using this set of SENB test data, a mathematical expression for the J-R curve of the A285 carbon steel can be developed. It is shown that the predicted J-R curves match well with the SENB data over an extensive amount of crack growth. In addition, this expression of the constraint modified J-R curve is used to predict the test data of a compact tension specimen (CT), and good agreement can be achieved. To demonstrate its application in the structural integrity assessment, a …
Date: March 13, 2002
Creator: Lam, P.S.
System: The UNT Digital Library
Determination of free hole concentration in ferromagnetic Ga(1-x)MnxAs using electrochemical capacitance-voltage profiling (open access)

Determination of free hole concentration in ferromagnetic Ga(1-x)MnxAs using electrochemical capacitance-voltage profiling

None
Date: March 13, 2002
Creator: Yu, K.M.; Walukiewicz, W.; Wojtowicz, T.; Lim, W.L.; Liu, X.; Sasaki, Y. et al.
System: The UNT Digital Library
High temperature oxidation of irradiated Limerick BWR cladding. (open access)

High temperature oxidation of irradiated Limerick BWR cladding.

None
Date: March 13, 2002
Creator: Yan, Y.; Strain, R. V.; Bray, T. S. & Billone, M. C.
System: The UNT Digital Library
Mechanisms of photo double ionization of helium by 530 eV photons (open access)

Mechanisms of photo double ionization of helium by 530 eV photons

None
Date: March 13, 2002
Creator: Knapp, A.; Kheifets, A.; Bray, I.; Weber, Th.; Landers, A. L.; Schossler, S. et al.
System: The UNT Digital Library
Migrating birds : assessment of impact on 915-MHz radar wind profiler performance at the Atmospheric Radiation Measurement Program's southern great plains. (open access)

Migrating birds : assessment of impact on 915-MHz radar wind profiler performance at the Atmospheric Radiation Measurement Program's southern great plains.

The U. S. Department of Energy's Atmospheric Radiation Measurement Program is running a small network of 915-MHz radar wind profilers (RWPs) at its Southern Great Plains Cloud and Radiation Testbed site in northern Oklahoma and southern Kansas. Seasonal migration of passerines may cause significant interference with the operation of 915-MHz RWPs. The extent of this ''bird jamming'' depends on the radar's parameters, the place of deployment, the season, and the time of day. This poster presents a new diagnostic method for detecting possible bird contamination in RWP data, along with an evaluation of the method using a three-year data set for two RWPs.
Date: March 13, 2002
Creator: Pekour, M. S.
System: The UNT Digital Library
Matrix model description of baryonic deformations (open access)

Matrix model description of baryonic deformations

We investigate supersymmetric QCD with N{sub c} + 1 flavors using an extension of the recently proposed relation between gauge theories and matrix models.The impressive agreement between the two sides provides a beautiful confirmation of the extension of the gauge theory-matrix model relation to this case.
Date: March 13, 2003
Creator: Bena, Iosif; Murayama, Hitoshi; Roiban, Radu & Tatar, Radu
System: The UNT Digital Library
Seismic imaging of reservoir flow properties: Time-lapse amplitude changes (open access)

Seismic imaging of reservoir flow properties: Time-lapse amplitude changes

Asymptotic methods provide an efficient means by which to infer reservoir flow properties, such as permeability, from time-lapse seismic data. A trajectory-based methodology, much like ray-based methods for medical and seismic imaging, is the basis for an iterative inversion of time-lapse amplitude changes. In this approach a single reservoir simulation is required for each iteration of the algorithm. A comparison between purely numerical and the trajectory-based sensitivities demonstrates their accuracy. An application to a set of synthetic amplitude changes indicates that they can recover large-scale reservoir permeability variations from time-lapse data. In an application of actual time-lapse amplitude changes from the Bay Marchand field in the Gulf of Mexico we are able to reduce the misfit by 81% in twelve iterations. The time-lapse observations indicate lower permeabilities are required in the central portion of the reservoir.
Date: March 13, 2003
Creator: Vasco, D.W.; Datta-Gupta, Akhil; Behrens, Ron; Condon, Pat & Rickett, Jame s
System: The UNT Digital Library
Big Talk and Even Bigger Crowds on Opening Weekend of SXSW '04 (open access)

Big Talk and Even Bigger Crowds on Opening Weekend of SXSW '04

Article about events that took place during the opening weekend of Austin's South by Southwest festival in 2004, including the Texas Film Hall of Fame Awards and the SXSW Film Conference and Festival.
Date: March 13, 2004
Creator: Hernandez, Eugene
System: The UNT Digital Library
FIRST-PRINCIPLES PHASE DIAGRAM OF THE Ce-Th SYSTEM (open access)

FIRST-PRINCIPLES PHASE DIAGRAM OF THE Ce-Th SYSTEM

Actinide physics has seen a remarkable focus the last decade or so due to the combination of improved experimental diamond-anvil-cell techniques and the development of fast computers and more advanced theory. All f-electron systems are expected to have multiphase phase diagrams due to the sensitivity of the f-electron band to external influences such as pressure and temperature. For instance, compression of an f-electron metal generally causes the occupation of f-states to change due to the shift of these bands relative to others. This can in some cases, as in the Ce-Th system, cause the crystal to adopt a lower symmetry structure at elevated pressures. Here we study the phase stabilities of Ce, Th, and the Ce-Th system as a function of compression. Theoretically, both Ce and Th metals are rather well described within the DFT, although a proper treatment of the Ce-Th alloys has not yet been presented. In the present paper we revisit this problem by applying the modern theory of random alloys based on the coherent potential approximation (CPA).
Date: March 13, 2005
Creator: Landa, A & Soderlind, P
System: The UNT Digital Library
Independence of replisomes in Escherichia coli chromosomalreplication (open access)

Independence of replisomes in Escherichia coli chromosomalreplication

In Escherichia coli DNA replication is carried out by the coordinated action of the proteins within a replisome. After replication initiation, the two bidirectionally oriented replisomes from a single origin are colocalized into higher-order structures termed replication factories. The factory model postulated that the two replisomes are also functionally coupled. We tested this hypothesis by using DNA combing and whole-genome microarrays. Nascent DNA surrounding oriC in single, combed chromosomes showed instead that one replisome, usually the leftward one, was significantly ahead of the other 70% of the time. We next used microarrays to follow replication throughout the genome by measuring DNA copy number. We found in multiple E. coli strains that the replisomes are independent, with the leftward replisome ahead of the rightward one. The size of the bias was strain-specific, varying from 50 to 130 kb in the array results. When we artificially blocked one replisome, the other continued unabated, again demonstrating independence. We suggest an improved version of the factory model that retains the advantages of threading DNA through colocalized replisomes at about equal rates, but allows the cell flexibility to overcome obstacles encountered during elongation.
Date: March 13, 2005
Creator: Breier, Adam M.; Weier, Heinz-Ulrich G. & Cozzarelli, Nicholas R.
System: The UNT Digital Library
Adaptive Optics Imaging Survey of Luminous Infrared Galaxies (open access)

Adaptive Optics Imaging Survey of Luminous Infrared Galaxies

We present high resolution imaging observations of a sample of previously unidentified far-infrared galaxies at z < 0.3. The objects were selected by cross-correlating the IRAS Faint Source Catalog with the VLA FIRST catalog and the HST Guide Star Catalog to allow for adaptive optics observations. We found two new ULIGs (with L{sub FIR} {ge} 10{sup 12} L{sub {circle_dot}}) and 19 new LIGs (with L{sub FIR} {ge} 10{sup 11} L{sub {circle_dot}}). Twenty of the galaxies in the sample were imaged with either the Lick or Keck adaptive optics systems in H or K{prime}. Galaxy morphologies were determined using the two dimensional fitting program GALFIT and the residuals examined to look for interesting structure. The morphologies reveal that at least 30% are involved in tidal interactions, with 20% being clear mergers. An additional 50% show signs of possible interaction. Line ratios were used to determine powering mechanism; of the 17 objects in the sample showing clear emission lines--four are active galactic nuclei and seven are starburst galaxies. The rest exhibit a combination of both phenomena.
Date: March 13, 2006
Creator: Laag, E. A.; Canalizo, G.; van Breugel, W.; Gates, E. L.; de Vries, W. & Stanford, S. A.
System: The UNT Digital Library