Analytic Expressions for Optimal ICF Hohlraum Wall Density and Wall Loss (open access)

Analytic Expressions for Optimal ICF Hohlraum Wall Density and Wall Loss

Solutions to the radiation diffusion equation predict the absorbed energy (''wall loss'') within an inertial confinement fusion (ICF) hohlraum. Comparing supersonic vs. subsonic solutions suggests that a high Z metallic foam as hohlraum wall material will reduce hydrodynamic losses, and hence, net absorbed energy by {approx}20%. We derive an analytic expression for the optimal density (for any given drive temperature and pulse-length) that will achieve this reduction factor and which agrees well with numerical simulations. This approach can reduce the cost of a reactor driver. Radiation heat waves, or Marshak waves, play an important role in energy transport and in the energy balance of laser, z-pinch and heavy ion beam hohlraums for ICF and high energy density physics experiments. In these experiments, a power source, e.g. a laser, delivers energy to the interior of a high Z cavity that is converted to x-rays. Typically, most of the energy is absorbed in a thin, diffusively heated layer on the hohlraum interior surface, and re-emission from the heated layer sets the radiation temperature T achieved in the hohlraum. In our recent paper, (henceforward referred to as HR) we developed an analytic theory of Marshak waves via a perturbation theory using a small …
Date: May 25, 2004
Creator: Rosen, M D & Hammer, J H
Object Type: Article
System: The UNT Digital Library
Calculating Expectations with Time-Dependent Perturbations in Quantum Monte Carlo (open access)

Calculating Expectations with Time-Dependent Perturbations in Quantum Monte Carlo

None
Date: May 25, 2004
Creator: Kalos, M H & de Saavedra, F A
Object Type: Article
System: The UNT Digital Library
Carbon Nanotube-Based Permeable Membranes: A Platform for Studying Nanofluidics (open access)

Carbon Nanotube-Based Permeable Membranes: A Platform for Studying Nanofluidics

A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Nitrogen flow measurements of a nanoporous silicon nitride membrane, fabricated by sacrificial removal of carbon, give a flow rate of 0.086 cc/sec. Calculations of water flow across a nanotube membrane give a rate of 2.1x10{sup -6} cc/sec (0.12 {micro}L/min).
Date: May 25, 2004
Creator: Holt, J K; Park, H G; Noy, A; Huser, T; Eaglesham, D & Bakajin, O
Object Type: Article
System: The UNT Digital Library
Coping With Contaminated Sediments and Soils in the Urban Environment. (open access)

Coping With Contaminated Sediments and Soils in the Urban Environment.

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

Defense Acquisitions: Knowledge of Software Suppliers Needed to Manage Risks

A letter report issued by the General Accounting Office with an abstract that begins "The Department of Defense (DOD) is increasingly reliant on software and information systems for its weapon capabilities, and DOD prime contractors are subcontracting more of their software development. The increased reliance on software and a greater number of suppliers results in more opportunities to exploit vulnerabilities in defense software. In addition, DOD has reported that countries hostile to the United States are focusing resources on information warfare strategies. Therefore, software security, including the need for protection of software code from malicious activity, is an area of concern for many DOD programs. GAO was asked to examine DOD's efforts to (1) identify software development suppliers and (2) manage risks related to foreign involvement in software development on weapon systems."
Date: May 25, 2004
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Federal Acquisition: Increased Attention to Vehicle Fleets Could Result in Savings (open access)

Federal Acquisition: Increased Attention to Vehicle Fleets Could Result in Savings

A letter report issued by the General Accounting Office with an abstract that begins "Federal agencies spend about $1.7 billion annually to operate a fleet of about 387,000 vehicles. During the last decade, concerns have been raised about whether agencies have more vehicles than they need. In an April 2002 letter to federal agencies, the Office of Management and Budget stated that the size of the federal fleet seemed excessive. GAO was asked to determine (1) the extent to which agencies ensure that their fleets are the right size to meet agency missions, (2) whether potential savings could result from the disposal of unneeded vehicles, and (3) what actions are being taken on a governmentwide basis to improve fleet management practices. GAO focused its review on the justification for acquiring and retaining vehicles at the Departments of Agriculture, Army, Homeland Security, Navy, and Veterans Affairs."
Date: May 25, 2004
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Final Progress Report: Direct Experiments on the Ocean Disposal of Fossil Fuel CO2. (open access)

Final Progress Report: Direct Experiments on the Ocean Disposal of Fossil Fuel CO2.

OAK-B135 This report summarizes activities and results of investigations of the potential environmental consequences of direct injection of carbon dioxide into the deep-sea as a carbon sequestration method. Results of field experiments using small scale in situ releases of liquid CO2 are described in detail. The major conclusions of these experiments are that mortality rates of deep sea biota will vary depending on the concentrations of CO2 in deep ocean waters that result from a carbon sequestration project. Large changes in seawater acidity and carbon dioxide content near CO2 release sites will likely cause significant harm to deep-sea marine life. Smaller changes in seawater chemistry at greater distances from release sites will be less harmful, but may result in significant ecosystem changes.
Date: May 25, 2004
Creator: Barry, James P. & Brewer, Peter G.
Object Type: Report
System: The UNT Digital Library
A "First Principles" Potential Energy Surface for Liquid Water from VRT Spectroscopy of Water Clusters (open access)

A "First Principles" Potential Energy Surface for Liquid Water from VRT Spectroscopy of Water Clusters

We present results of gas phase cluster and liquid water simulations from the recently determined VRT(ASP-W)III water dimer potential energy surface. VRT(ASP-W)III is shown to not only be a model of high ''spectroscopic'' accuracy for the water dimer, but also makes accurate predictions of vibrational ground-state properties for clusters up through the hexamer. Results of ambient liquid water simulations from VRT(ASP-W)III are compared to those from ab initio Molecular Dynamics, other potentials of ''spectroscopic'' accuracy, and to experiment. The results herein represent the first time that a ''spectroscopic'' potential surface is able to correctly model condensed phase properties of water.
Date: May 25, 2004
Creator: Goldman, N.; Leforestier, C. & Saykally, R. J.
Object Type: Article
System: The UNT Digital Library
From Sequential Extraction to Transport Modeling, Monitored Natural Attenuation as a Remediation Approach for Inorganic Contaminants (open access)

From Sequential Extraction to Transport Modeling, Monitored Natural Attenuation as a Remediation Approach for Inorganic Contaminants

Implementation of monitored natural attenuation (MNA) as a remediation method requires a mechanistic understanding of the natural attenuation processes occurring at a given site. For inorganic contaminants, natural attenuation typically involves a decrease in metal toxicity and/or mobility. These natural processes include dilution, dispersion, sorption (including adsorption, absorption, and precipitation), and redox processes. In order to better quantify these processes in terms of metal availability, sequential extraction experiments were carried out on subsurface soil samples impacted by a low pH, high sulfate, metals (Be, Ni, U, As) plume associated with the long-term operation of a coal plant at the Savannah River Site. These laboratory scale studies provide mechanistic information regarding the solid phases in the soils associated with natural attenuation of the contaminant metals. This data provides input to be evaluated in the definition of the contaminant source term as well as transport of contaminants for site transport models.
Date: May 25, 2004
Creator: POWELL, KIMBERLYR.
Object Type: Article
System: The UNT Digital Library
Hydrogen Storage Properties of the Tetrahydrofuran Treated Magnesium (open access)

Hydrogen Storage Properties of the Tetrahydrofuran Treated Magnesium

The electronic structure, crystalline feature and morphology of the tetrahydrofuran (THF) treated magnesium, along with its hydriding and dehydriding properties have been investigated. The THF treated magnesium absorbs 6.3 wt per cent hydrogen at 723K and 3.5 MPa. After hydrogenation, in addition to the expected MgH2, a new less-stable hydride phase appears at 673K, but not at a lower temperature. Desorption produces 5.5 wt per cent hydrogen at 723K against a back pressure of 1.3 Pa after 20 cycles of hydriding-dehydriding. The THF treatment improves the kinetics of hydrogen absorption and desorption significantly. From 723K to 623K, the THF treated Mg demonstrates acceptable reaction rates. XPS studies show that tetrahydrofuran treatment causes the electronic energy state of the magnesium surface atoms to change, but the XRD studies show the crystal structure remains unchanged. Metallographic observation of the bulk hydrides of THF treated magnesium reveal they are poly-crystalline wi th the wide-spreading slip bands and twins within the crystals, indicating the phase transformation upon hydriding causes serious stress and distortion. It appears this microstructural deformation explains the much higher energy requirements (higher pressure and temperature) for magnesium hydrogenation than the simple lattice expansion that accompany hydrogen uptake for LaNi5 and FeTi.
Date: May 25, 2004
Creator: AU, MING
Object Type: Article
System: The UNT Digital Library
The Individuals with Disabilities Education Act (IDEA): Comparison and Analysis of Selected Provisions in H.R. 1350 as Passed by the House and by the Senate, 108th Congress (open access)

The Individuals with Disabilities Education Act (IDEA): Comparison and Analysis of Selected Provisions in H.R. 1350 as Passed by the House and by the Senate, 108th Congress

This report discusses select changes and amendments made by the House and the Senate to the Individuals with Disabilities Education Act (IDEA).
Date: May 25, 2004
Creator: Jones, Nancy Lee & Apling, Richard N.
Object Type: Report
System: The UNT Digital Library
Interferometric resolution boosting for spectrographs (open access)

Interferometric resolution boosting for spectrographs

Externally dispersed interferometry (EDI) is a technique for enhancing the performance of spectrographs for wide bandwidth high resolution spectroscopy and Doppler radial velocimetry. By placing a small angle-independent interferometer near the slit of a spectrograph, periodic fiducials are embedded on the recorded spectrum. The multiplication of the stellar spectrum times the sinusoidal fiducial net creates a moir{acute e} pattern, which manifests high detailed spectral information heterodyned down to detectably low spatial frequencies. The latter can more accurately survive the blurring, distortions and CCD Nyquist limitations of the spectrograph. Hence lower resolution spectrographs can be used to perform high resolution spectroscopy and radial velocimetry. Previous demonstrations of {approx}2.5x resolution boost used an interferometer having a single fixed delay. We report new data indicating {approx}6x Gaussian resolution boost (140,000 from a spectrograph with 25,000 native resolving power), taken by using multiple exposures at widely different interferometer delays.
Date: May 25, 2004
Creator: Erskine, D J & Edelstein, J
Object Type: Article
System: The UNT Digital Library
Iraq's Transitional Law (open access)

Iraq's Transitional Law

Correspondence issued by the General Accounting Office with an abstract that begins "On June 30, 2004, the Coalition Provisional Authority (CPA) intends to transfer power in Iraq to a fully sovereign Iraqi interim government. CPA and the Iraq Governing Council took a fundamental step toward this goal in March 2004, when they signed the Law of Administration for the State of Iraq for the Transitional Period (hereafter referred to as the transitional law). The transitional law is intended to govern the affairs of Iraq until Iraqis approve a permanent constitution and a permanent Iraqi government takes office. GAO has ongoing and completed work reviewing various aspects of the U.S. effort to reconstruct Iraq. Our ongoing work includes reviewing the costs associated with reconstruction; the process used to award reconstruction contracts; efforts to develop Iraq's security forces; the rebuilding of Iraq's oil, electricity, and water infrastructure; and programs to help Iraq develop a unified, democratic government. For this report, we describe the following information as it exists at this time: (1) the time frames and Iraqi governmental structures established by the transitional law; (2) arrangements in the law for the U.S.-led multinational force, Iraqi security forces, and militias; and (3) mechanisms …
Date: May 25, 2004
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library

Managing the Yucca Mountain Project's Cultural Resources

None
Date: May 25, 2004
Creator: Bishop, L.
Object Type: Presentation
System: The UNT Digital Library
Patents and Drug Importation (open access)

Patents and Drug Importation

This report explores the intellectual property laws and policies concerning the parallel importation of patented pharmaceuticals into the United States.
Date: May 25, 2004
Creator: Thomas, John R.
Object Type: Report
System: The UNT Digital Library
ProteinShop: A tool for interactive protein manipulation and steering (open access)

ProteinShop: A tool for interactive protein manipulation and steering

We describe ProteinShop, a new visualization tool that streamlines and simplifies the process of determining optimal protein folds. ProteinShop may be used at different stages of a protein structure prediction process. First, it can create protein configurations containing secondary structures specified by the user. Second, it can interactively manipulate protein fragments to achieve desired folds by adjusting the dihedral angles of selected coil regions using an Inverse Kinematics method. Last, it serves as a visual framework to monitor and steer a protein structure prediction process that may be running on a remote machine. ProteinShop was used to create initial configurations for a protein structure prediction method developed by a team that competed in CASP5. ProteinShop's use accelerated the process of generating initial configurations, reducing the time required from days to hours. This paper describes the structure of ProteinShop and discusses its main features.
Date: May 25, 2004
Creator: Crivelli, Silvia; Kreylos, Oliver; Max, Nelson; Hamann, Bernd & Bethel, Wes
Object Type: Article
System: The UNT Digital Library
Radiation dose measurements of the insertion devices using radiachromic film dosimeters. (open access)

Radiation dose measurements of the insertion devices using radiachromic film dosimeters.

The Advanced Photon Source (APS) uses Nd-Fe-B permanent magnets in the insertion devices to produce x-rays for scientific research [1,2]. Earlier investigations have exhibited varying degrees of demagnetization of these magnets [3] due to irradiation from electron beams [4,5,6], {sup 60}Co {gamma}-rays [5], and high-energy neutrons [7,8]. Radiation-induced demagnetization has been observed in the APS insertion devices [9] and was first measured in December of 2001. Partial demagnetization has also been observed in insertion devices at the European Synchrotron Radiation Facility (ESRF) [4,6], where Nd-Fe-B permanent magnets are also used. Growing concern for the lifetime of APS insertion devices, as well as the permanent magnets that will be used in next-generation, high-power light sources, like the FEL [10,11], resulted from the partial demagnetization observations made at both facilities. This concern in relation to radiation-induced demagnetization spurred a long-term project to measure and analyze the absorbed doses received by the APS insertion devices. The project required a reliable photon high-dose dosimetry technique capable of measuring absorbed doses greater than 10{sup 6} rad, which was not readily available at the APS. Through a collaboration with the National Institute of Standards and Technology (NIST), one such technique using radiachromic films was considered, tested, …
Date: May 25, 2004
Creator: Alderman, J.; Semones, E. & Job, P. K.
Object Type: Report
System: The UNT Digital Library

Rail Alignment Environmental Impact Statement Information Session

None
Date: May 25, 2004
Creator: Sweeney, R.
Object Type: Presentation
System: The UNT Digital Library
Ultrasonic Examination of Double-Shell Tank 241-SY-101. Examination Completed March 2004. (open access)

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

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

Yucca Mountain Project Archaeological Studies

None
Date: May 25, 2004
Creator: Rhode, Dr. Dave & Varley, K.
Object Type: Presentation
System: The UNT Digital Library