States

Connecting atomistic and experimental estimates of ideal strength (open access)

Connecting atomistic and experimental estimates of ideal strength

None
Date: April 1, 2001
Creator: Krenn, C.R.; Roundy, D.; Cohen, M.L.; Chrzan, D.C. & Morris Jr., J.W.
Object Type: Article
System: The UNT Digital Library
Advanced Light Source Activity Report: 2000 (open access)

Advanced Light Source Activity Report: 2000

This is an annual report, detailing activities at the Advanced Light Source for the year 2000. It includes highlights of scientific research by users of the facility as well as information about the development of the facility itself.
Date: April 1, 2001
Creator: Greiner, A.; Moxon, L.; Robinson, A. & Tamura, L.
Object Type: Report
System: The UNT Digital Library
Final technical report: The effect of physical and chemical heterogeneities in a porous medium on the transport of bacteria (open access)

Final technical report: The effect of physical and chemical heterogeneities in a porous medium on the transport of bacteria

Among the demonstrated processes influencing the transport of bacteria through aquifers, the deposition of cells on mineral surfaces is one of the most important. Heterogeneous distribution of aquifer properties such as mineral-grain oxide coatings and preferred flow paths can control the numbers of microbes arriving a point down gradient from their injection, and these properties can also affect the distribution of the organisms remaining in the sedimentary matrix. The distribution of metal oxide coatings affects the final location of retained cells within the matrix but had no effect on total breakthrough of applied bacteria. We were able to demonstrate transverse mixing of both conservative tracers and bacteria between regions of differing hydraulic conductivity; the conservative tracer could be used to model the transverse mixing of the bacteria. We were able to show that the presence of metal oxide coatings on aquifer surfaces retarded a reactive tracer (SO{sub 4}{sup 2-}) that simulated bacterial retardation in the laboratory. When metal oxide coatings were absent (due to bacterial establishment of a reducing environment) the tracer and bacteria were not retarded. The effect was reproduced in a tracer experiment done in the field. The results suggest that bacterial transport in the subsurface is controlled …
Date: April 1, 2001
Creator: Hornberger, George M.; Mills, Aaron L. & Herman, Janet S.
Object Type: Report
System: The UNT Digital Library
Texas Construction and Maintenance Report: April 2001 (open access)

Texas Construction and Maintenance Report: April 2001

Monthly report documenting contracts for road construction and maintentance in Texas, organized by county and district. It includes information about each project including contractor, dates, costs, and other relevant data.
Date: April 1, 2001
Creator: Texas. Department of Transportation. Construction Division.
Object Type: Report
System: The Portal to Texas History
OPERATIONS OF THE LEDA RESONANTLY COUPLED RFQ (open access)

OPERATIONS OF THE LEDA RESONANTLY COUPLED RFQ

The LEDA RFQ is a 350-MHz continuous-wave (CW) radio-frequency quadrupole linac. LEDA is the low energy demonstration accelerator, a full power front-end prototype for the accelerator production of tritium (APT) linac. This machine has accelerated a 100-mA CW proton beam from 75 keV to 6.7 MeV. The 8-m-long RFQ accepts a dc, 75-keV, {approximately}110-mA H{sup +} beam from the LEDA injector, bunches the beam, and accelerates it to full energy with {approximately}94% transmission. Output beam power is 670 kW. This RFQ consists of four 2-meter-long RFQs joined with resonant coupling to form an 8-meter-long RFQ. The resonant coupling improves the stability of both the longitudinal and transverse RF-field distribution in this long RFQ.
Date: April 1, 2001
Creator: YOUNG, L. M.
Object Type: Article
System: The UNT Digital Library
Direct participation of electrical loads in the California independent system operator markets during the Summer of 2000 (open access)

Direct participation of electrical loads in the California independent system operator markets during the Summer of 2000

California's restructured electricity markets opened on 1 April 1998. The former investor-owned utilities were functionally divided into generation, transmission, and distribution activities, all of their gas-fired generating capacity was divested, and the retail market was opened to competition. To ensure that small customers shared in the expected benefit of lower prices, the enabling legislation mandated a 10% rate cut for all customers, which was implemented in a simplistic way that fossilized 1996 tariff structures. Rising fuel and environmental compliance costs, together with a reduced ability to import electricity, numerous plant outages, and exercise of market power by generators drove up wholesale electricity prices steeply in 2000, while retail tariffs remained unchanged. One of the distribution/supply companies entered bankruptcy in April 2001, and another was insolvent. During this period, two sets of interruptible load programs were in place, longstanding ones organized as special tariffs by the distribution/supply companies and hastily established ones run directly by the California Independent System Operator (CAISO). The distribution/supply company programs were effective at reducing load during the summer of 2000, but because of the high frequency of outages required by a system on the brink of failure, customer response declined and many left the tariff. The …
Date: April 1, 2001
Creator: Marnay, Chris; Hamachi, Kristina S.; Khavkin, Mark & Siddiqui, Afzal S.
Object Type: Article
System: The UNT Digital Library
De-Alerting and De-Activating Strategic Nuclear Weapons (open access)

De-Alerting and De-Activating Strategic Nuclear Weapons

Despite the end of the Cold War, the US and Russia continue to maintain their ICBMs and many SLBMs in a highly alerted state--they are technically prepared to launch the missiles within minutes of a command decision to do so. Some analysts argue that, particularly in light of the distressed condition of the Russian military, these high alert conditions are tantamount to standing on the edge of a nuclear cliff from which we should now step back. They have proposed various bilateral ''de-alerting'' measures, to be taken prior to and outside the context of the formal strategic arms reduction treaty (START) process. This paper identifies several criteria for a stable de-alerting regime, but fails to find de-alerting measures that convincingly satisfy the criteria. However, some de-alerting measures have promise as de-activation measures for systems due for elimination under the START II and prospective START III treaties. Moreover, once these systems are deactivated, a considerable part of the perceived need to keep nuclear forces on high alert as a survivability hedge will be reduced. At the same time, the U.S. and Russia could consider building on their earlier cooperative actions to reduce the risk of inadvertent nuclear war by enhancing their …
Date: April 1, 2001
Creator: Karas, Thomas H.
Object Type: Report
System: The UNT Digital Library
HYBRID MESOSCALE MODELING OF DYNAMIC GRAIN FRAGMENTATION (open access)

HYBRID MESOSCALE MODELING OF DYNAMIC GRAIN FRAGMENTATION

Fines created by grain fragmentation from shaped-charge, jet perforation treatment often plug-up pores in the vicinity of the perforation tunnel. We analyze and model grain damage on samples recovered from impact tests of dry and water saturated sandstone at stress levels and duration similar to that of perforation loading. Analyses of Scanning Electron Microscope (SEM) images and laser particle size measurements on portions of the recovered samples characterize grain damage and changes in grain size distribution. Hybrid modeling that combines the Discrete Element Method (DEM) with Smooth Particle Hydrodynamics (SPH), and includes mesoscale representation of grain/pore structure, shows how grain damage evolves for dry and wet conditions. Modeling defines behavior in accord with recovered sample analyses as follows: (1) Increase in grain damage is obtained with an increase in stress level and pulse duration. (2) The grains in dry samples are extremely and irregularly fragmented with extensive reduced porosity. (3) Less grain damage and higher porosity is obtained in saturated samples. The influence of pore fluid mitigates the interaction between grains, thus reducing fragmentation damage. (4) Computed particle size distributions are similar in character to measurements.
Date: April 1, 2001
Creator: SWIFT, R.; HAGELBERG, C. & HILTL, M.
Object Type: Article
System: The UNT Digital Library
Formation of Random, RIE-Textured Silicon Surfaces with Reduced Reflection and Enhanced Near IR Absorption (open access)

Formation of Random, RIE-Textured Silicon Surfaces with Reduced Reflection and Enhanced Near IR Absorption

The authors have developed novel metal-assisted texturing processes that have led to optically favorable surfaces for solar cells. Large area ({approximately} 200 cm{sup 2}) uniform texturing has been achieved. The physical dimensions of the chamber limited texturing of even larger wafers. Surface contamination and residual RIE-induced damage were removed by incorporation of a complete RCA clean process followed by wet-chemical etching treatments. RIE-textured solar cells with optimized profiles providing performance comparable to the random, wet-chemically etched cells have been demonstrated. A majority of the texture profiles exhibit an enhanced IQE response in the near IR region.using scanning electron microscope measurements, they carried out a detailed analysis of the microstructure of random RIE-textured surfaces. The random microstructure represents a superposition of sub-{micro}m grating structures with a wide distribution of periods, depths, and profiles as determined by the SEM measurements. These structures were modeled using GSOLVER{trademark} software for periodic patterns. The enhanced IR response from random, RIE-textured surfaces is attributed to enhanced coupling of light into the transmitted diffraction orders. These obliquely propagating diffraction orders generate electron-hole pairs closer to the surface, thus, reducing bulk recombination losses relative to a non-scattering, planar surface with identical hemispherical reflection. The optimized texture and damage …
Date: April 1, 2001
Creator: ZAIDI, SALEEM H
Object Type: Report
System: The UNT Digital Library
Current Filament Semiconductor Lasers (CFSL) (open access)

Current Filament Semiconductor Lasers (CFSL)

None
Date: April 1, 2001
Creator: Zutavern, Fred J.; Baca, Albert G.; Chow, Weng W.; Hafich, Michael J.; Hjalmarson, Harold P.; Loubriel, Guillermo M. et al.
Object Type: Report
System: The UNT Digital Library
Genetic control of nitrate assimilation in Klebsiella oxytoca. Final technical report (open access)

Genetic control of nitrate assimilation in Klebsiella oxytoca. Final technical report

Some microorganisms can use nitrate as the sole source of nitrogen for biosynthesis. This project focused on the bacterium Klebsiella oxytoca, an enterobacterium found in soil and water. Mutagenesis and molecular cloning identified the nasFEDCBA operon encoding enzymes for the uptake and reduction of nitrate and nitrite to ammonium, and the adjacent nasR regulatory gene. Analysis of nasF operon expression revealed that transcription is activated by the Ntr (general nitrogen regulation ) system in response to nitrogen limitation. Transcription antitermination control in response to nitrate and nitrite is mediated by the NasR protein. Additional work established that the NasR protein is an RNA-binding protein that interacts with nasF operon leader RNA to control transcription readthrough.
Date: April 1, 2001
Creator: Stewart, Valley J.
Object Type: Report
System: The UNT Digital Library
THE HIGH-HEAT FLUX TESTING OF AN INTERCEPTIVE DEVICE FOR AN INTENSE PROTON BEAM (open access)

THE HIGH-HEAT FLUX TESTING OF AN INTERCEPTIVE DEVICE FOR AN INTENSE PROTON BEAM

An interceptive device referred to here as a scraper has been designed and tested for use in a diagnostic device [1]. The scraper will be used to probe a proton beam in order to detect the formation of beam halo [2]. Probing the proton beam exposes the scraper to high heat fluxes on the order of 610 kW/cm{sup 2}. The high-heat flux exposure is cyclic since the beam is probed while in pulsed mode. In order to test the design repetitive high-heat flux testing has been performed on a prototype design of the scraper. This paper describes the design, analysis, and testing of the scraper.
Date: April 1, 2001
Creator: VALDIVIEZ, R.; MARTINEZ, F. A. & AL, ET
Object Type: Article
System: The UNT Digital Library
Characterization of Leak Pathways in the Below Grade Ducts of the Brookhaven Graphite Research Reactor Using Perfluorocarbon Tracers (open access)

Characterization of Leak Pathways in the Below Grade Ducts of the Brookhaven Graphite Research Reactor Using Perfluorocarbon Tracers

The focus of this program was the characterization of the soils beneath the main air ducts connecting the exhaust plenums with the Fan House. The air plenums experienced water intrusion during BGRR operations and after shutdown. The water intrusions were attributed to rainwater leaks into degraded parts of the system and to internal cooling water system leaks. As part of the overall characterization efforts, a state-of-the-art gaseous perfluorocarbon tracer technology was utilized to characterize leak pathways from the ducts. This in turn suggests what soil regions under or adjacent to the ductwork should be emphasized in the characterization process. Knowledge of where gaseous tracers leak from the ducts yields a conservative picture of where water transport, out of or into, the ducts might have occurred.
Date: April 1, 2001
Creator: Heiser, J.; Sullivan, T.; Kalb, P.; Milian, L.; Wilke, R.; Newson, C. et al.
Object Type: Report
System: The UNT Digital Library
Supporting Technology for Enhanced Oil Recovery-EOR Thermal Processes Report IV-12 (open access)

Supporting Technology for Enhanced Oil Recovery-EOR Thermal Processes Report IV-12

This report contains the results of efforts under the six tasks of the Ninth Amendment and Extension of Annex IV, Enhanced Oil Recovery Thermal Processes of the Venezuela/USA Agreement. The report is presented in sections (for each of the 6 tasks) and each section contains one or more reports prepared by various individuals or groups describing the results of efforts under each of the tasks. A statement of each task, taken from the agreement, is presented on the first page of each section. The tasks are numbered 62 through 67. The first, second, third, fourth, fifth, sixth, seventh, eight, and ninth reports on Annex IV, [Venezuela MEM/USA-DOE Fossil Energy Report IV-1, IV-2, IV-3, IV-4, IV-5, IV-6, IV-7, and IV-8 (DOE/BETC/SP-83/15, DOE/BC-84/6/SP, DOE/BC-86/2/SP, DOE/BC-87/2/SP, DOE/BC-89/1/SP, DOE/BC-90/1/SP) DOE/BC-92/1/SP, DOE/BC-93/3/SP, and DOE/BC-95/3/SP] contain the results from the first 61 tasks. Those reports are dated April 1983, August 1984, March 1986, July 1! 987, November 1988, December 1989, October 1991, February 1993, and March 1995 respectively.
Date: April 1, 2001
Creator: Izequeido, Alexandor
Object Type: Report
System: The UNT Digital Library
Dislocations in MO5SIB2 T2 Phase (open access)

Dislocations in MO5SIB2 T2 Phase

None
Date: April 1, 2001
Creator: Field, R.; Cooley, J. & AL, ET
Object Type: Article
System: The UNT Digital Library
Captive Rearing Initiative for Salmon River Chinook Salmon, 1998-1999 Progress Report. (open access)

Captive Rearing Initiative for Salmon River Chinook Salmon, 1998-1999 Progress Report.

During 1999, the Idaho Department of Fish and Game (IDFG) continued developing techniques for the captive rearing of chinook salmon Oncorhynchus tshawytscha. Techniques under development included protocols for rearing juveniles in freshwater and saltwater hatchery environments, and fieldwork to collect brood year 1998 and 1999 juveniles and eggs and to investigate the ability of these fish to spawn naturally. Fish collected as juveniles were held for a short time at the Sawtooth Fish Hatchery and later transferred to the Eagle Fish Hatchery for rearing. Eyed-eggs were transferred immediately to the Eagle Fish Hatchery where they were disinfected and reared by family groups. When fish from either collection method reached approximately 60 mm, they were PIT tagged and reared separately by brood year and source stream. Sixteen different groups were in culture at IDFG facilities in 1999. Hatchery spawning activities of captive-reared chinook salmon produced eyed-eggs for outplanting in streamside incubation chambers in the West Fork Yankee Fork Salmon River (N=2,297) and the East Fork Salmon River (N=1,038). Additionally, a number of these eggs were maintained at the Eagle Fish Hatchery to ensure adequate brood year 1999 representation from these systems, and produced 279 and 87 juveniles from the West Fork …
Date: April 1, 2001
Creator: Hassemer, Peter F.
Object Type: Report
System: The UNT Digital Library
THE REMEDIATION OF ABANDONED IRON ORE MINE SUBSIDENCE IN ROCKAWAY TOWNSHIP, NEW JERSEY (open access)

THE REMEDIATION OF ABANDONED IRON ORE MINE SUBSIDENCE IN ROCKAWAY TOWNSHIP, NEW JERSEY

This report represents the seventh Semi-Annual Technical Progress Report issued in connection with the subsidence remediation projects undertaken by Rockaway Township in Morris County, New Jersey. This report provides a summary of the major project work accomplished during this reporting period and contemplated for the subsequent reporting period. This report is issued as part of the project reporting provisions set forth in the Cooperators Agreement between the United States Government--Department of Energy, and Rockaway Township. The purpose of the Cooperators Agreement is for the Department of Energy to provide technical and financial assistance in a coordinated effort with Rockaway Township to develop and implement a multi-phased plan to remediate ground stability problems associated with abandoned mining activity. Primarily during the 1800's, extensive iron ore mining and prospecting was undertaken in Rockaway Township, part of the Dover District Mining region in Morris County. The abandoned mining activity has resulted in public safety hazards associated with ground collapse and surface subsidence features evolving in both developed and undeveloped areas within Rockaway Township. At the Green Pond Mine site at the Township Compost Storage Facility, research and preliminary design was performed during this reporting period toward development of the engineering plans and Technical …
Date: April 1, 2001
Creator: Gary Gartenberg, P.E., P.P.
Object Type: Report
System: The UNT Digital Library
General Stability Models for Potential IE-911 Column Plugging Materials (open access)

General Stability Models for Potential IE-911 Column Plugging Materials

None
Date: April 1, 2001
Creator: Krumhansl, James L.; Zhang, Pengchu; Jove-Colon, Carlos F. & Anderson, Howard L.
Object Type: Report
System: The UNT Digital Library
MEASURES OF DISTORTION IN POSSIBILISTIC APPROXIMATIONS OF CONSISTENT RANDOM SETS AND INTERVALS (open access)

MEASURES OF DISTORTION IN POSSIBILISTIC APPROXIMATIONS OF CONSISTENT RANDOM SETS AND INTERVALS

The availability of probability or possibility measures for random set (Dempster-Shafer evidence theoretical) structures are highly desirable. Probabilistic conditions involve disjointness or specificity, while possibilistic conditions involve consonance of the underlying focal elements. Consistency results in possibilistic distributions, but not measures, but then a unique approximation is available. Especially in random interval measurement situations, this condition is common. In this paper we develop some of the mathematical ideas necessary to develop a measure of the distortion introduced by this consonant approximation of a consistent random set.
Date: April 1, 2001
Creator: JOSLYN, C.
Object Type: Article
System: The UNT Digital Library
SOUTHERN FINE PARTICULATE MONITORING PROJECT (open access)

SOUTHERN FINE PARTICULATE MONITORING PROJECT

This is the second quarterly progress report of the ''Southern Fine Particulate Monitoring Project'', funded by the U.S. Department of Energy's National Energy Technology Laboratory under DOE Cooperative Agreement No. DE-FC26-00NT40770 to Southern Research Institute (SRI). In this two year project SRI will conduct detailed studies of ambient fine particulate matter in the Birmingham, AL metropolitan area. Project objectives include: Augment existing measurements of primary and secondary aerosols at an established urban southeastern monitoring site; Make a detailed database of near-continuous measurements of the time variation of fine particulate mass, composition, and key properties (including particle size distribution); Apply the measurements to source attribution, time/transport properties of fine PM, and implications for management strategies for PM{sub 2.5}; and Validate and compare key measurement methods used in this study for applicability within other PM{sub 2.5} research by DOE-FE, EPA, NARSTO, and others.
Date: April 1, 2001
Creator: Williamson, Ashley D.
Object Type: Report
System: The UNT Digital Library
Quark-Hadron Duality in Structure Functions (open access)

Quark-Hadron Duality in Structure Functions

While quark-hadron duality is well-established experimentally, the current theoretical understanding of this important phenomenon is quite limited. To expose the essential features of the dynamics behind duality, we use a simple model in which the hadronic spectrum is dominated by narrow resonances made of valence quarks. We qualitatively reproduce the features of duality as seen in electron scattering data within our model. We show that in order to observe duality, it is essential to use the appropriate scaling variable and scaling function. In addition to its great intrinsic interest in connecting the quark-gluon and hadronic pictures, an understanding of quark-hadron duality could lead to important benefits in extending the applicability of scaling into previously inaccessible regions.
Date: April 1, 2001
Creator: Isgur, Nathan; Jeschonnek, Sabine; Melnitchouk, Wally & Orden, J.W. Van
Object Type: Article
System: The UNT Digital Library
Photonics Integration Devices and Technologies (open access)

Photonics Integration Devices and Technologies

We have used selective AlGaAs oxidation, dry-etching, and high-gain semiconductor laser simulation to create new in-plane lasers with interconnecting passive waveguides for use in high-density photonic circuits and future integration of photonics with electronics. Selective oxidation and doping of semiconductor heterostructures have made vertical cavity surface emitting lasers (VCSELs) into the world's most efficient low-power lasers. We apply oxidation technology to improve edge-emitting lasers and photonic-crystal waveguides, making them suitable for monolithic integrated microsystems. Two types of lasers are investigated: (1) a ridge laser with resonant coupling to an output waveguide; (2) a selectively-oxidized laser with a low active volume and potentially sub-milliAmp threshold current. Emphasis is on development of high-performance lasers suited for monolithic integration with photonic circuit elements.
Date: April 1, 2001
Creator: Vawter, Gregory A.; Lin, Shawn-Yu; Sullivan, Charles T.; Zubrzycki, Walter J.; Chow, Weng W.; Allerman, Andrew A. et al.
Object Type: Report
System: The UNT Digital Library
International Symposia on High Energy Spin Physics. Final report on project grant (open access)

International Symposia on High Energy Spin Physics. Final report on project grant

The U.S. Department of Energy High Energy Physics Division provided $10,000 during 1997-1998, as partial support for the 1998 International Symposium on High Energy Spin Physics, which has been held every second September since 1974, and for its five associated Workshops that usually focus on some particular technical issue which is currently important to the field of High Energy Spin Physics. Similar funds were provided by Argonne Universities Association (AUA) during 1974-1978, by University of Michigan during 1979- 1994 and 1999-2004, and by DOE during 1995-1996. These Symposia and Workshops serve as a focus for the important, but technically difficult, field of High Energy Spin Physics, which requires state-of-the-art spin-polarized beams and spin-polarized targets. The Symposia and Workshops are guided by the standing International Committee for High Energy Spin Physics Symposia, which approves the content and location of the Symposia and Workshops. The Committee's Members are elected to 4-year terms; some of the more active and/or distinguished Members have served a number of terms. The Proceeding of each Symposium or Workshop is published, usually by a publisher near the meeting site.
Date: April 1, 2001
Creator: Krisch, A. D.
Object Type: Report
System: The UNT Digital Library
A RATIONALE FOR IMPLICIT TURBULENCE MODELING (open access)

A RATIONALE FOR IMPLICIT TURBULENCE MODELING

We present a rationale for the success of nonoscillatory finite volume (NFV) difference schemes in modeling turbulent flows without need of subgrid scale models. Our exposition focuses on certain truncation terms that appear in the modified equation of one particular NFV scheme, MPDATA. We demonstrate that these truncation terms have physical justification, representing the modifications to the governing equations that arise when one considers the motion of finite volumes of fluid over finite intervals of time.
Date: April 1, 2001
Creator: MARGOLIN, L. G. & RIDER, W. J.
Object Type: Article
System: The UNT Digital Library