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Disaster Housing: Implementation of FEMA's Alternative Housing Pilot Program Provides Lessons for Improving Future Competitions (open access)

Disaster Housing: Implementation of FEMA's Alternative Housing Pilot Program Provides Lessons for Improving Future Competitions

Correspondence issued by the Government Accountability Office with an abstract that begins "The Department of Homeland Security's (DHS) Federal Emergency Management Agency (FEMA) provides direct temporary housing assistance in response to disasters primarily through a combination of travel trailers and manufactured homes and for a period of up to 18 months. In 2005, Hurricanes Katrina and Rita devastated much of the housing stock across the Gulf Coast region, leaving thousands of persons in need of temporary housing for lengthy periods. Uncertainty with respect to neighborhood and community recovery and individual and community resistance to the use of travel trailers for extended temporary housing challenged the effectiveness of FEMA's traditional temporary housing options. Recognizing these challenges, Congress, in the Fiscal Year 2006 Emergency Supplemental Appropriations Act for Defense, the Global War on Terror, and Hurricane Recovery, provided for alternative housing pilot programs in the areas hardest hit by Hurricane Katrina and the other hurricanes of the 2005 season, and appropriated $400 million to DHS for this purpose. To implement this provision of law, FEMA announced a competitive grant program--the Alternative Housing Pilot Program (AHPP)--inviting the five Gulf Coast states (Alabama, Florida, Louisiana, Mississippi, and Texas) to submit proposals for projects that …
Date: August 31, 2007
Creator: United States. Government Accountability Office.
Object Type: Text
System: The UNT Digital Library
Social Security Administration: Policies and Procedures Were in Place over MMA Spending, but Some Instances of Noncompliance Occurred (open access)

Social Security Administration: Policies and Procedures Were in Place over MMA Spending, but Some Instances of Noncompliance Occurred

A letter report issued by the Government Accountability Office with an abstract that begins "The Medicare Prescription Drug, Improvement, and Modernization Act of 2003 (MMA) created a voluntary outpatient prescription drug benefit as part of the Medicare program, and appropriated up to $500 million for the Social Security Administration (SSA) to fund the start-up administrative costs in meeting its responsibilities to implement MMA. SSA was given a great deal of discretion in how to use the funds and the act provided little detail on how the funds were to be spent. You asked us to review SSA's costs for implementing MMA to determine (1) how the MMA funds were expended, (2) what procedures SSA has in place over the use of those funds, and (3) how SSA complied with those procedures related to contractor and vendor payments."
Date: August 31, 2007
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Homeland Security: U.S. Visitor and Immigrant Status Program's Long-standing Lack of Strategic Direction and Management Controls Needs to Be Addressed (open access)

Homeland Security: U.S. Visitor and Immigrant Status Program's Long-standing Lack of Strategic Direction and Management Controls Needs to Be Addressed

A letter report issued by the Government Accountability Office with an abstract that begins "The Department of Homeland Security (DHS) has established a program known as U.S. Visitor and Immigrant Status Indicator Technology (US-VISIT) to collect, maintain, and share information, including biometric identifiers, on certain foreign nationals who travel to the United States. By congressional mandate, DHS is to develop and submit an expenditure plan for US-VISIT that satisfies certain conditions, including being reviewed by GAO. GAO reviewed the plan to (1) determine if the plan satisfied these conditions, (2) follow up on certain recommendations related to the program, and (3) provide any other observations. To address the mandate, GAO assessed plans and related documentation against federal guidelines and industry standards and interviewed the appropriate DHS officials."
Date: August 31, 2007
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Military Personnel: DOD's Predatory Lending Report Addressed Mandated Issues, but Support Is Limited for Some Findings and Recommendations (open access)

Military Personnel: DOD's Predatory Lending Report Addressed Mandated Issues, but Support Is Limited for Some Findings and Recommendations

Correspondence issued by the Government Accountability Office with an abstract that begins "Serious financial problems can adversely affect unit morale and readiness as well as servicemembers' credit histories and military careers. If servicemembers experience serious financial problems, they may be subject to adverse actions such as loss of security clearances, criminal or nonjudicial sanctions, or adverse personnel actions including possible discharge from the military. The Department of Defense's (DOD) Social Compact, which is part of its human capital plan, notes that mission readiness and quality of life depend on whether servicemembers use their financial resources responsibly. For these reasons, Congress and DOD officials have expressed concerns about servicemembers' financial conditions. DOD is particularly concerned about the use and effects of certain consumer loans that DOD identified as being predatory. The 2006 National Defense Authorization Act required DOD to issue a report on predatory lending directed at servicemembers and their dependents. The mandate required DOD's report to include: (1) a description of the prevalence of predatory lending practices directed at servicemembers and their families; (2) an assessment of the effects of predatory lending on servicemembers and their families; (3) a description of DOD's strategies and programs to educate servicemembers and their …
Date: August 31, 2007
Creator: United States. Government Accountability Office.
Object Type: Text
System: The UNT Digital Library
Defense Infrastructure: Management Actions Needed to Ensure Effectiveness of DOD's Risk Management Approach for the Defense Industrial Base (open access)

Defense Infrastructure: Management Actions Needed to Ensure Effectiveness of DOD's Risk Management Approach for the Defense Industrial Base

A letter report issued by the Government Accountability Office with an abstract that begins "The U.S. military relies on the defense industrial base (DIB) to meet requirements to fulfill the National Military Strategy. The potential destruction, incapacitation, or exploitation of critical DIB assets by attack, crime, technological failure, natural disaster, or man-made catastrophe could jeopardize the success of U.S. military operations. GAO was asked to review the Department of Defense's (DOD) Defense Critical Infrastructure Program and has already reported that DOD has not developed a comprehensive management plan for its implementation. This, the second GAO report, has (1) determined the status of DOD's efforts to develop and implement a risk management approach to ensure the availability of DIB assets, and (2) identified challenges DOD faces in its approach to risk management. GAO analyzed plans, guidance, and other documents on identifying, prioritizing, and assessing critical domestic and foreign DIB assets and held discussions with DOD and contractor officials."
Date: August 31, 2007
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Information Security: Selected Departments Need to Address Challenges in Implementing Statutory Requirements (open access)

Information Security: Selected Departments Need to Address Challenges in Implementing Statutory Requirements

A letter report issued by the Government Accountability Office with an abstract that begins "The Federal Information Security Management Act of 2002 (FISMA) strengthened security requirements by, among other things, requiring federal agencies to establish programs to provide cost-effective security for information and information systems. In overseeing FISMA implementation, the Office of Management and Budget (OMB) has established supporting processes and reporting requirements. However, 4 years into implementation of the act, agencies have not yet fully implemented key provisions. In this context, GAO determined what challenges or obstacles inhibit the implementation of the information security provisions of FISMA at the Departments of Defense, Homeland Security, Justice, and State. To do this, GAO reviewed and analyzed department policies, procedures, and reports related to department information security programs and interviewed agency officials."
Date: August 31, 2007
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Calcium Carbonate Storage in Amorphous Form and Its Template-Induced Crystallization (open access)

Calcium Carbonate Storage in Amorphous Form and Its Template-Induced Crystallization

Calcium carbonate crystallization in organisms often occurs through the transformation from the amorphous precursor. It is believed that the amorphous phase could be temporarily stabilized and stored, until its templated transition to the crystalline form is induced. Here we develop a bio-inspired crystallization strategy that is based on the above mechanism. Amorphous calcium carbonate (ACC) spherulitic particles are formed and stabilized on a self-assembled monolayer (SAM) of hydroxy-terminated alkanethiols on Au surface. The ACC is stored as a reservoir for ions and is induced to crystallize on command by introducing a secondary surface that is functionalized with carboxylic acid-terminated SAM. This secondary surface acts as a template for oriented and patterned nucleation. Various oriented crystalline arrays and micropatterned films are formed. We also show that the ACC phase can be doped with foreign ions (e.g. Mg) and organic molecules (e.g. dyes) and that these dopants later function as growth modifiers of calcite crystals and become incorporated into the crystals during the transformation process of ACC to calcite. We believe that our strategy opens the way of using a stabilized amorphous phase as a versatile reservoir system that can be converted in a highly controlled fashion to a crystalline form upon …
Date: August 31, 2007
Creator: Han, T Y & Aizenberg, J
Object Type: Article
System: The UNT Digital Library
Supercement for Annular Seal and Long-Term Integrity in Deep, Hot Wells "DeepTrek" (open access)

Supercement for Annular Seal and Long-Term Integrity in Deep, Hot Wells "DeepTrek"

The purpose of this project is to formulate a 'Supercement' designed for improving the long-term sealing integrity in HPHT wells. Phase I concentrated on chemistry studies and screening tests to design and evaluate Portland-based, hybrid Portland, and non-Portland-based cement systems suitable for further scale-up testing. Phase II work concentrated on additional lab and field testing to reduce the candidate materials list to two systems, as well as scaleup activities aimed at verifying performance at the field scale. Phase II was extended thorough a proposal to develop additional testing capabilities aimed at quantifying cementing material properties and performance that were previously not possible. Phase III focused on bringing the material(s) developed in previous Phases to commercialization, through Field Trials, Cost/Benefit Analysis, and Technology Transfer. Extensive development and testing work throughout the project led to Phase III commercialization of two very different materials: (1) Highly-expansive cement (Portland-based), patent pending as 'PRESTRESSED CEMENT'; and (2) Epoxy Resin (non-Portland-based), patent pending. Trade name is Ultra Seal-R. In Phase III, work concentrated on application of the Supercement materials in various increasingly-challenging wells. Previous testing revealed that PRESTRESSED CEMENT, when applied in weak or unconsolidated formations, tends to expand away from the central pipe, restricting the …
Date: August 31, 2007
Creator: Technologies, CSI
Object Type: Report
System: The UNT Digital Library
Optical alignment techniques for line-imaging velocity interferometry and line-imaging self-emulsion of targets at the National Ignition Facility (NIF) (open access)

Optical alignment techniques for line-imaging velocity interferometry and line-imaging self-emulsion of targets at the National Ignition Facility (NIF)

The National Ignition Facility (NIF) requires optical diagnostics for measuring shock velocities in shock physics experiments. The Velocity Interferometer System for Any Reflector (VISAR) measures shock velocities, shock breakout times, and emission of 1- to 5-mm targets at a location remote to the NIF target chamber. Three optical systems using the same vacuum chamber port each have a total track of 69 feet. All optical lenses are on kinematic mounts or sliding rails, enabling pointing accuracy of the optical axis to be checked. Counter-propagating laser beams (orange and red) align these diagnostics to a listing of tolerances. The orange alignment laser is introduced at the entrance to the two-level interferometer table and passes forward through the optical systems to the recording streak cameras. The red alignment laser is introduced in front of the recording streak cameras and passes in the reverse direction through all optical elements, out of the interferometer table, eventually reaching the target chamber center. Red laser wavelength is selected to be at the 50 percent reflection point of a special beamsplitter used to separate emission light from the Doppler-shifted interferometer light. Movable aperture cards, placed before and after lens groups, show the spread of alignments spots created …
Date: August 31, 2007
Creator: Robert M. Malone, Brent C. Frogget, Morris I. Kaufman, Thomas W. Tunnell, Robert L. Guyton, Imants P. Reinbachs, Phillip W. Watts, et al.
Object Type: Article
System: The UNT Digital Library
Mercuric Iodide Photocell Technology for Room Temperature Readout of Scintillators (open access)

Mercuric Iodide Photocell Technology for Room Temperature Readout of Scintillators

Mercuric iodide (HgI2) is a well known material for the direct detection of gamma rays; however, the largest volume achievable is limited by thickness of the detector, which needs to be a small fraction of the average trapping length for electrons. We are reporting here preliminary results in using HgI2 crystals to fabricate photocells used in the readout of various scintillators. The optical spectral response and efficiency of these photocells were measured and will be reported. Preliminary nuclear response from a HgI2 photocell that was optically matched to a Ce3+ :LaBr3 scintillator will also be presented and discussed. Further improvements will be sought by optimizing the transparent contact technology.
Date: August 31, 2007
Creator: al., Warnick Kernan et
Object Type: Article
System: The UNT Digital Library
Harsh-Environment Packaging for Downhole Gas and Oil Exploration (open access)

Harsh-Environment Packaging for Downhole Gas and Oil Exploration

This research into new packaging materials and methods for elevated temperatures and harsh environment electronics focused on gaining a basic understanding of current state-of-the-art in electronics packaging used in industry today, formulating the thermal-mechanical models of the material interactions and developing test structures to confirm these models. Discussions were initiated with the major General Electric (GE) businesses that currently sell into markets requiring high temperature electronics and packaging. They related the major modes of failure they encounter routinely and the hurdles needed to be overcome in order to improve the temperature specifications of these products. We consulted with our GE business partners about the reliability specifications and investigated specifications and guidelines that from IPC and the SAE body that is currently developing guidelines for electronics package reliability. Following this, a risk analysis was conducted for the program to identify the critical risks which need to be mitigated in order to demonstrate a flex-based packaging approach under these conditions. This process identified metal/polyimide adhesion, via reliability for flex substrates and high temperature interconnect as important technical areas for reliability improvement.
Date: August 31, 2007
Creator: Bansal, Shubhra; Cho, Junghyun; Durocher, Kevin; Kapusta, Chris; Knobloch, Aaron; Shaddock, David et al.
Object Type: Report
System: The UNT Digital Library
Michrochannel plate for position sensitive alpha particle detection (open access)

Michrochannel plate for position sensitive alpha particle detection

This paper will describe the use of a microchannel plate (MCP) as the associated particle detector on a sealed tube neutron generator. The generator produces neutrons and associated alpha particles for use as a probe to locate and identify hidden explosives in associated particle imaging (API). The MCP measures the position in two dimensions and precise timing of the incident alpha particle, information which is then used to calculate the emission time and direction of the corresponding neutron. The MCP replaces the position-sensitive photomultipler tube (PSPMT) which, until recently, had been the only detector available for measuring position and timing for alpha particles in neutron generator applications. Where the PSPMT uses charge division for generating position information, a process that requires a first order correction to each pulse, the MCP uses delay-line timing, which requires no correction. The result is a device with an order of magnitude improvement in both position resolution and timing compared to the PSPMT. Hardware and software development and the measurements made to characterize the MCP for API applications are described.
Date: August 31, 2007
Creator: Tinsley, Paul Hurley and James
Object Type: Article
System: The UNT Digital Library
Final Report for Fractionation and Separation of Polydisperse Nanoparticles into Distinct Monodisperse Fractions Using CO2 Expanded Liquids (open access)

Final Report for Fractionation and Separation of Polydisperse Nanoparticles into Distinct Monodisperse Fractions Using CO2 Expanded Liquids

The overall objective of this project was to facilitate efficient fractionation and separation of polydisperse metal nanoparticle populations into distinct monodisperse fractions using the tunable solvent properties of gas expanded liquids. Specifically, the dispersibility of ligand-stabilized nanoparticles in an organic solution was controlled by altering the ligand-solvent interaction (solvation) by the addition of carbon dioxide (CO{sub 2}) gas as an antisolvent (thereby tailoring the bulk solvent strength) in a custom high pressure apparatus developed in our lab. This was accomplished by adjusting the CO{sub 2} pressure over the liquid dispersion, resulting in a simple means of tuning the nanoparticle precipitation by size. Overall, this work utilized the highly tunable solvent properties of organic/CO{sub 2} solvent mixtures to selectively size-separate dispersions of polydisperse nanoparticles (ranging from 1 to 20 nm in size) into monodisperse fractions ({+-}1nm). Specifically, three primary tasks were performed to meet the overall objective. Task 1 involved the investigation of the effects of various operating parameters (such as temperature, pressure, ligand length and ligand type) on the efficiency of separation and fractionation of Ag nanoparticles. In addition, a thermodynamic interaction energy model was developed to predict the dispersibility of different sized nanoparticles in the gas expanded liquids at …
Date: August 31, 2007
Creator: Roberts, Chistopher
Object Type: Report
System: The UNT Digital Library
Bridging the Pressure Gap in Water and Hydroxyl Chemistry on MetalSurfaces: the Cu(110) case (open access)

Bridging the Pressure Gap in Water and Hydroxyl Chemistry on MetalSurfaces: the Cu(110) case

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Date: August 31, 2007
Creator: Andersson, K.; Ketteler, G.; Hendrik, B.; Yamamoto, S.; Ogasawara, H.; Pettersson, L.G.M. et al.
Object Type: Article
System: The UNT Digital Library
Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks (open access)

Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks

This is the final technical report for the project titled 'Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks'. The aim of the project was to develop an efficient chemistry model for combustion simulations. The reduced chemistry model was developed mathematically without the need of having extensive knowledge of the chemistry involved. To aid in the development of the model, Neural Networks (NN) was used via a new network topology known as Non-linear Principal Components Analysis (NPCA). A commonly used Multilayer Perceptron Neural Network (MLP-NN) was modified to implement NPCA-NN. The training rate of NPCA-NN was improved with the GEneralized Regression Neural Network (GRNN) based on kernel smoothing techniques. Kernel smoothing provides a simple way of finding structure in data set without the imposition of a parametric model. The trajectory data of the reaction mechanism was generated based on the optimization techniques of genetic algorithm (GA). The NPCA-NN algorithm was then used for the reduction of Dimethyl Ether (DME) mechanism. DME is a recently discovered fuel made from natural gas, (and other feedstock such as coal, biomass, and urban wastes) which can be used in compression ignition engines as a substitute for diesel. An in-house two-dimensional Computational Fluid Dynamics (CFD) code …
Date: August 31, 2007
Creator: Huque, Ziaul
Object Type: Report
System: The UNT Digital Library
Improving Paper Machine Efficiency/Productivity through On-line Control (open access)

Improving Paper Machine Efficiency/Productivity through On-line Control

This project involves implementing a new technology, microforming, in a headbox to produce an isotropic sheet with significant reductions in the MD/CD stiffness ratio (increasing CD specific STFI) and improved sheet uniformity. Microforming involves generating axial vorticity (i.e., swirl) prior to the converging nozzle of the headbox by retrofitting an existing tube block with swirl generation devices referred to as Vortigen system. The Vortigen system developed in this project is a retrofit technology to a hydraulic headbox tube block. The tubes in the tube block are re-designed to generate axial vorticity (or swirl) in the tubes. This type of flow results in higher intensity small-scale turbulence in the forming jet at the slice. The net effect, as demonstrated in pilot and commercial trials, is improvement in formation and surface smoothness, lower MD/CD tensile ratio, and consequently, higher CD strength properties such as CD STFI, Ring Crush and tensile or breaking length. The objective of this project is to implement microforming by developing the retrofit technology for generation and on-line control of axial vorticity in the tubes to optimize turbulent scale and intensity, and consequently, fiber network structure properties in the sheet. This technology results in significant improvements in the performance …
Date: August 31, 2007
Creator: Aidun, Cyrus K
Object Type: Report
System: The UNT Digital Library
Field Deployable Gamma Radiation Detectors for DHS Use (open access)

Field Deployable Gamma Radiation Detectors for DHS Use

Recently, the U.S. Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS’s requirements in terms of sensitivity, resolution, response time and reach back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron’s identiFINDER™, which primarily uses sodium iodide crystals (3.18-cm x 2.54-cm cylinders) as gamma detector, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack™ that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with …
Date: August 31, 2007
Creator: Mukhopadhyay, Sanjoy
Object Type: Article
System: The UNT Digital Library
Final Project Report: DOE Award FG02‐04ER25606 Overlay Transit Networking for Scalable, High Performance Data Communication across Heterogeneous Infrastructure (open access)

Final Project Report: DOE Award FG02‐04ER25606 Overlay Transit Networking for Scalable, High Performance Data Communication across Heterogeneous Infrastructure

As the flood of data associated with leading edge computational science continues to escalate, the challenge of supporting the distributed collaborations that are now characteristic of it becomes increasingly daunting. The chief obstacles to progress on this front lie less in the synchronous elements of collaboration, which have been reasonably well addressed by new global high performance networks, than in the asynchronous elements, where appropriate shared storage infrastructure seems to be lacking. The recent report from the Department of Energy on the emerging 'data management challenge' captures the multidimensional nature of this problem succinctly: Data inevitably needs to be buffered, for periods ranging from seconds to weeks, in order to be controlled as it moves through the distributed and collaborative research process. To meet the diverse and changing set of application needs that different research communities have, large amounts of non-archival storage are required for transitory buffering, and it needs to be widely dispersed, easily available, and configured to maximize flexibility of use. In today's grid fabric, however, massive storage is mostly concentrated in data centers, available only to those with user accounts and membership in the appropriate virtual organizations, allocated as if its usage were non-transitory, and encapsulated behind …
Date: August 31, 2007
Creator: Beck, Micah & Moore, Terry
Object Type: Report
System: The UNT Digital Library
Experimental Plan: 300 Area Treatability Test: In Situ Treatment of the Vadose Zone and Smear Zone Uranium Contamination by Polyphosphate Infiltration (open access)

Experimental Plan: 300 Area Treatability Test: In Situ Treatment of the Vadose Zone and Smear Zone Uranium Contamination by Polyphosphate Infiltration

The overall objectives of the treatability test is to evaluate and optimize polyphosphate remediation technology for infiltration either from ground surface, or some depth of excavation, providing direct stabilization of uranium within the deep vadose and capillary fringe above the 300 Area aquifer. Expected result from this experimental plan is a data package that includes: 1) quantification of the retardation of polyphosphate, 2) the rate of degradation and the retardation of degradation products as a function of water content, 3) an understanding of the mechanism of autunite formation via the reaction of solid phase calcite-bound uranium and aqueous polyphosphate remediation technology, 4) an understanding of the transformation mechanism, identity of secondary phases, and the kinetics of the reaction between uranyl-carbonate and –silicate minerals with the polyphosphate remedy under solubility-limiting conditions, 5) quantification of the extent and rate of uranium released and immobilized based on the infiltration rate of the polyphosphate remedy and the effect of and periodic wet-dry cycling on the efficacy of polyphosphate remediation for uranium in the vadose zone and capillary fringe, and 6) quantification of reliable equilibrium solubility values for autunite under hydraulically unsaturated conditions allowing accurate prediction of the long-term stability of autunite. Moreover, results of …
Date: August 31, 2007
Creator: Wellman, Dawn M.; Pierce, Eric M.; Oostrom, Mart & Fruchter, Jonathan S.
Object Type: Report
System: The UNT Digital Library
Design, construction, alignment, and calibration of a compact velocimetry experiment (open access)

Design, construction, alignment, and calibration of a compact velocimetry experiment

A velocimetry experiment has been designed to measure shock properties for small, cylindrical, metal targets (8 mm diameter × 2 mm thick). A target is accelerated by high explosives, caught, then retrieved for later inspection. The target is expected to move at a velocity of 0.1 to 3 km/sec. The complete experiment canister is ~105 mm in diameter and 380 mm long. Optical velocimetry diagnostics include the Velocity Interferometer System for Any Reflector (VISAR) and photon Doppler velocimetry (PDV). The packaging of the velocity diagnostics is not allowed to interfere with the foam catchment or an X-ray imaging diagnostic. Using commercial lenses, a single optical relay collects Doppler-shifted light for both VISAR and PDV. The use of fiber optics allows measurement of point velocities on the target surface for accelerations lasting for 3 mm of travel. Operating at 532 nm, the VISAR has separate illumination fibers requiring alignment. The PDV diagnostic operates at 1550 nm but is aligned and calibrated at 670 nm. VISAR and PDV diagnostics are complimentary measurements that image spots in close proximity on the target surface. Because the optical relay uses commercial glass, optical fibers’ axial positions are offset to compensate for chromatic aberrations. The optomechanical …
Date: August 31, 2007
Creator: Kaufman, Morris I.; Malone, Robert M.; Frogget, Brent C.; Romero, Vincent T.; Esquibel, David L.; Iverson, Adam et al.
Object Type: Article
System: The UNT Digital Library
Target designs for energetics experiments on the National Ignition Facility (open access)

Target designs for energetics experiments on the National Ignition Facility

The goal of the first hohlraum energetics experiments on the National Ignition Facility (NIF) [G. H. Miller et al , Optical Eng. 43, 2841 (2004)] is to select the hohlraum design for the first ignition experiments. Sub-scale hohlraums heated by 96 of the 192 laser beams on the NIF are used to emulate the laser-plasma interaction behavior of ignition hohlraums. These ''plasma emulator'' targets are 70% scale versions of the 1.05 MJ, 300 eV ignition hohlraum and have the same energy-density as the full-scale ignition designs. Radiation-hydrodynamics simulations show that the sub-scale target is a good emulator of plasma conditions inside the ignition hohlraum, reproducing density ne within 10% and temperature Te within 15% along a laser beam path. Linear backscatter gain analysis shows the backscatter risk to be comparable to that of the ignition target. A successful energetics campaign will allow the National Ignition Campaign to focus its efforts on optimizing ignition hohlraums with efficient laser coupling.
Date: August 31, 2007
Creator: Meezan, N B; Glenzer, S H & Suter, L J
Object Type: Article
System: The UNT Digital Library
Feasibility study for use of the natural convection shutdown heat removal test facility (NSTF) for VHTR water-cooled RCCS shutdown. (open access)

Feasibility study for use of the natural convection shutdown heat removal test facility (NSTF) for VHTR water-cooled RCCS shutdown.

In summary, a scaling analysis of a water-cooled Reactor Cavity Cooling System (RCCS) system was performed based on generic information on the RCCS design of PBMR. The analysis demonstrates that the water-cooled RCCS can be simulated at the ANL NSTF facility at a prototypic scale in the lateral direction and about half scale in the vertical direction. Because, by necessity, the scaling is based on a number of approximations, and because no analytical information is available on the performance of a reference water-cooled RCCS, the scaling analysis presented here needs to be 'validated' by analysis of the steady state and transient performance of a reference water-cooled RCCS design. The analysis of the RCCS performance by CFD and system codes presents a number of challenges including: strong 3-D effects in the cavity and the RCCS tubes; simulation of turbulence in flows characterized by natural circulation, high Rayleigh numbers and low Reynolds numbers; validity of heat transfer correlations for system codes for heat transfer in the cavity and the annulus of the RCCS tubes; the potential of nucleate boiling in the tubes; water flashing in the upper section of the RCCS return line (during limiting transient); and two-phase flow phenomena in the …
Date: August 31, 2007
Creator: Tzanos, C. P. & Farmer, M. T.
Object Type: Report
System: The UNT Digital Library
Environmentally Assisted Cracking in Light Water Reactors Annual Report January - December 2005.A (open access)

Environmentally Assisted Cracking in Light Water Reactors Annual Report January - December 2005.A

This report summarizes work performed from January to December 2005 by Argonne National Laboratory on fatigue and environmentally assisted cracking in light water reactors (LWRs). Existing statistical models for estimating the fatigue life of carbon and low-alloy steels and austenitic stainless steels (SSs) as a function of material, loading, and environmental conditions were updated. Also, the ASME Code fatigue adjustment factors of 2 on stress and 20 on life were critically reviewed to assess the possible conservatism in the current choice of the margins. An approach, based on an environmental fatigue correction factor, for incorporating the effects of LWR environments into ASME Section III fatigue evaluations is discussed. The susceptibility of austenitic stainless steels and their welds to irradiation-assisted stress corrosion cracking (IASCC) is being evaluated as a function of the fluence level, water chemistry, material chemistry, and fabrication history. For this task, crack growth rate (CGR) tests and slow strain rate tensile (SSRT) tests are being conducted on various austenitic SSs irradiated in the Halden boiling water reactor. The SSRT tests are currently focused on investigating the effects of the grain boundary engineering process on the IASCC of the austenitic SSs. The CGR tests were conducted on Type 316 …
Date: August 31, 2007
Creator: Alexandreanu, B.; Chen, Y.; Chopra, O. K.; Chung, H. M.; Gruber, E. E.; Shack, W. J. et al.
Object Type: Report
System: The UNT Digital Library
Free Electron Lasers and High-Energy Electron Cooling. (open access)

Free Electron Lasers and High-Energy Electron Cooling.

Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation of such beams is too feeble to provide significant cooling: even in the Large Hadron Collider (LHC) with 7 TeV protons, the longitudinal damping time is about thirteen hours. Decrements of traditional electron cooling decrease rapidly as the high power of beam energy, and an effective electron cooling of protons or antiprotons at energies above 100 GeV seems unlikely. Traditional stochastic cooling still cannot catch up with the challenge of cooling high-intensity bunched proton beams--to be effective, its bandwidth must be increased by about two orders-of-magnitude. Two techniques offering the potential to cool high-energy hadron beams are optical stochastic cooling (OSC) and coherent electron cooling (CEC)--the latter is the focus of this paper. In the early 1980s, CEC was suggested as a possibility for using various instabilities in an electron beam to enhance its interaction with hadrons (i.e., cooling them). The capabilities of present-day accelerator technology, Energy Recovery Linacs (ERLs), and high-gain Free-Electron Lasers (FELs), finally caught up with the idea and provided the all necessary ingredients for realizing such a process. In this paper, we discuss the principles, and the main limitations of the …
Date: August 31, 2007
Creator: Litvinenko, V. N.
Object Type: Article
System: The UNT Digital Library