HIGH-INTENSITY, HIGH CHARGE-STATE HEAVY ION SOURCES (open access)

HIGH-INTENSITY, HIGH CHARGE-STATE HEAVY ION SOURCES

There are many accelerator applications for high intensity heavy ion sources, with recent needs including dc beams for RIA, and pulsed beams for injection into synchrotrons such as RHIC and LHC. The present status of sources producing high currents of high charge state heavy ions is reviewed. These sources include ECR, EBIS, and Laser ion sources. Benefits and limitations for these type sources are described. Possible future improvements in these sources are also mentioned.
Date: August 16, 2004
Creator: ALESSI,J. G.
Object Type: Article
System: The UNT Digital Library
Modeling the Transport and Chemical Evolution of Onshore and Offshore Emissions and their Impact on Local and Regional Air Quality Using a Variable-Grid-Resolution Air Quality Model (open access)

Modeling the Transport and Chemical Evolution of Onshore and Offshore Emissions and their Impact on Local and Regional Air Quality Using a Variable-Grid-Resolution Air Quality Model

This semiannual report summarizes the research performed from 17 April through 16 October 2004. Major portions of the research in several of the project's current eight tasks have been completed, and the results obtained are briefly presented. We have successfully developed the meteorological inputs using the best possible modeling configurations, resulting in improved representation of atmospheric processes. Ingestion of satellite-derived sea surface temperatures in conjunction with the use of our new surface data assimilation technique have resulted in largely improved meteorological inputs to drive the MAQSIP-VGR. The development of the variable-grid-resolution emissions model, SMOKE-VGR, is also largely complete. We expect to develop the final configuration of the SMOKE-VGR during the upcoming reporting period. We are in the process of acquiring the newly released emissions database and offshore emissions data sets to update our archives. The development of the MAQSIP-VGR has been completed and a test run was performed to ensure the functionality of this air quality model. During the upcoming reporting period, we expect to perform the first MAQSIP-VGR simulations over the Houston-Galveston region to study the roles of the meteorology, offshore emissions, and chemistry-transport interactions that determine the temporal and spatial evolution of ozone and its precursors.
Date: October 16, 2004
Creator: Alapaty, Kiran
Object Type: Report
System: The UNT Digital Library
Observation of Self-Sputtering in Energetic Condensation of Metal Ions (open access)

Observation of Self-Sputtering in Energetic Condensation of Metal Ions

The condensation of energetic metal ions on a surface may cause self-sputtering even in the absence of substrate bias. Charge-state-averaged self-sputtering yields were determined for both zirconium and gold ions generated by a cathodic vacuum arc. Films were deposited on differently biased substrates exposed to streaming Zr and Au vacuum arc plasma. The self-sputtering yields for both metals were estimated to be about 0.05 in the absence of bias, and exceeding 0.5 when bias reached-50 V. These surprisingly high values can be reconciled with binary collision theory and molecular dynamics calculations taking high the kinetic and potential energy of vacuum arc ions into account.
Date: June 16, 2004
Creator: Anders, Andre
Object Type: Article
System: The UNT Digital Library
Report on the Threatened Valley Elderberry Longhorn Beetle and its Elderberry Food Plant at the Lawrence Livermore National Laboratory--Site 300 (open access)

Report on the Threatened Valley Elderberry Longhorn Beetle and its Elderberry Food Plant at the Lawrence Livermore National Laboratory--Site 300

This report describes the results of an entomological survey in 2002 to determine the presence of the federally-listed, threatened Valley Elderberry Longhorn Beetle or ''VELB'' (Desmocerus culifornicus dimorphus: Coleoptera, Cerambycidae) and its elderberry food plant (Sumbucus mexicana: Caprifoliaceae) on the Lawrence Livermore National Laboratory's (LLNL) Experimental Test Site, known as Site 300. In addition, an area located immediately southeast of Site 300, which is owned and managed by the California Department of Fish and Game (CDFG), but secured by LLNL, was also included in this survey. This report will refer to the survey areas as the LLNL-Site 300 and the CDFG site. The 2002 survey included mapping the locations of elderberry plants that were observed using a global positioning system (GPS) to obtain positional coordinates for every elderberry plant at Site 300. In addition, observations of VELB adults and signs of their infestation on elderberry plants were also mapped using GPS technology. LLNL requested information on the VELB and its elderberry food plants to update earlier information that had been collected in 1991 (Arnold 1991) as part of the 1992 EIS/EIR for continued operation of LLNL. No VELB adults were observed as part of this prior survey. The findings of …
Date: November 16, 2004
Creator: Arnold, R. A. & Woollett, J.
Object Type: Report
System: The UNT Digital Library
Method of Evaluating, Expanding, and Collapsing Connectivity Regions Within Dynamic Systems (open access)

Method of Evaluating, Expanding, and Collapsing Connectivity Regions Within Dynamic Systems

An automated process defines and maintains connectivity regions within a dynamic network. The automated process requires an initial input of a network component around which a connectivity region will be defined. The process automatically and autonomously generates a region around the initial input, stores the region's definition, and monitors the network for a change. Upon detecting a change in the network, the effect is evaluated, and if necessary the regions are adjusted and redefined to accommodate the change. Only those regions of the network affected by the change will be updated. This process eliminates the need for an operator to manually evaluate connectivity regions within a network. Since the automated process maintains the network, the reliance on an operator is minimized; thus, reducing the potential for operator error. This combination of region maintenance and reduced operator reliance, results in a reduction of overall error.
Date: November 16, 2004
Creator: Bailey, David A.
Object Type: Patent
System: The UNT Digital Library
Dynamic Maintenance and Visualization of Molecular Surfaces (open access)

Dynamic Maintenance and Visualization of Molecular Surfaces

Molecular surface computations are often necessary in order to perform synthetic drug design. A critical step in this process is the computation and update of an exact boundary representation for the molecular surface (e.g. the Lee-Richards surface). In this paper they introduce efficient techniques for computing a molecular surface boundary representation as a set of NURBS (non-uniform rational B-splines) patches. This representation introduces for molecules the same geometric data structure used in the solid modeling community and enables immediate access to a wide range of modeling operations and techniques. Furthermore, this allows the use of any general solid modeling or visualization system as a molecular modeling interface. However, using such a representation in a molecular modeling environment raises several efficiency and update constraints, especially in a dynamic setting. For example, changes in the probe radius result in both geometric and topological changes to the set of patches. The techniques provide the option of trading accuracy of the representation for the efficiency of the computation, while still tracking the changes in the set of patches. In particular, they discuss two main classes of dynamic updates: one that keeps the topology of the molecular configuration fixed, and a more complicated case where …
Date: December 16, 2004
Creator: Bajaj, C L; Pascucci, V; Shamir, A; Holt, R J & Netravali, A N
Object Type: Article
System: The UNT Digital Library
Measurement of Cross Sections for the 63Cu(alpha,gamma)67Ga Reaction from 5.9-8.7 MeV (open access)

Measurement of Cross Sections for the 63Cu(alpha,gamma)67Ga Reaction from 5.9-8.7 MeV

None
Date: September 16, 2004
Creator: Basunia, M. S.; Norman, E. B.; Shugart, H. A.; Smith, A. R.; Dolinski, M. J. & Quiter, B. J.
Object Type: Article
System: The UNT Digital Library
Agricultural Biotechnology: The U.S.-EU Dispute (open access)

Agricultural Biotechnology: The U.S.-EU Dispute

This report focuses on a conflict between the European Union (EU) and the United States, Canada, and Argentina. The United States suggests that the European Union's moratorium costs the U.S. 300 million dollars in exports to the EU annually. Moreover, the report highlights other concerns the U.S. has with the EU's biotechnology policies.
Date: March 16, 2004
Creator: Becker, Geoffrey S. & Hanrahan, Charles E.
Object Type: Report
System: The UNT Digital Library
AMR for low Mach number reacting flow (open access)

AMR for low Mach number reacting flow

We present a summary of recent progress on the development and application of adaptive mesh refinement algorithms for low Mach number reacting flows. Our approach uses a form of the low Mach number equations based on a general equation of state that discretely conserves both mass and energy. The discretization methodology is based on a robust projection formulation that accommodates large density contrasts. The algorithm supports modeling of multicomponent systems and incorporates an operator-split treatment of stiff reaction terms. The basic computational approach is embedded in an adaptive projection framework that uses structured hierarchical grids with subcycling in time that preserves the discrete conservation properties of the underlying single-grid algorithm. We present numerical examples illustrating the application of the methodology to turbulent premixed combustion and nuclear flames in type Ia supernovae.
Date: January 16, 2004
Creator: Bell, John B.
Object Type: Article
System: The UNT Digital Library
Bounds and self-consistent estimates for elastic constants of random polycrystals with hexagonal, trigonal, and tetragonal symmetries (open access)

Bounds and self-consistent estimates for elastic constants of random polycrystals with hexagonal, trigonal, and tetragonal symmetries

Peselnick, Meister, and Watt have developed rigorous methods for bounding elastic constants of random polycrystals based on the Hashin-Shtrikman variational principles. In particular, a fairly complex set of equations that amounts to an algorithm has been presented previously for finding the bounds on effective elastic moduli for polycrystals having hexagonal, trigonal, and tetragonal symmetries. The more analytical approach developed here, although based on the same ideas, results in a new set of compact formulas for all the cases considered. Once these formulas have been established, it is then straightforward to perform what could be considered an analytic continuation of the formulas (into the region of parameter space between the bounds) that can subsequently be used to provide self-consistent estimates for the elastic constants in all cases. These self-consistent estimates are easily shown (essentially by construction) to lie within the bounds for all the choices of crystal symmetry considered. Estimates obtained this way are quite comparable to those found by the Gubernatis and Krumhansl CPA (coherent potential approximation), but do not require any computations of scattering coefficients.
Date: September 16, 2004
Creator: Berger, E. L.
Object Type: Article
System: The UNT Digital Library
Comparison of two up-scaling methods in poroelasticity and its generalizations (open access)

Comparison of two up-scaling methods in poroelasticity and its generalizations

Two methods of up-scaling coupled equations at the microscale to equations valid at the mesoscale and/or macroscale for fluid-saturated and partially saturated porous media are discussed, compared, and contrasted. The two methods are: (1) two-scale and multiscale homogenization, and (2) volume averaging. Both these methods have advantages for some applications and disadvantages for others. For example, homogenization methods can give formulas for coefficients in the up-scaled equations, whereas volume averaging methods give the form of the up-scaled equations but generally must be supplemented with physical arguments and/or data in order to determine the coefficients. Homogenization theory requires a great deal of mathematical insight from the user in order to choose appropriate scalings for use in the resulting power-law expansions, while volume averaging requires more physical insight to motivate the steps needed to find coefficients. Homogenization often is performed on periodic models, while volume averaging does not require any assumption of periodicity and can therefore be related very directly to laboratory and/or field measurements. Validity of the homogenization process is often limited to specific ranges of frequency - in order to justify the scaling hypotheses that must be made - and therefore cannot be used easily over wide ranges of frequency. …
Date: March 16, 2004
Creator: Berger, E. L.
Object Type: Article
System: The UNT Digital Library
Atomic and Molecular Facility at the Advanced Light Source (open access)

Atomic and Molecular Facility at the Advanced Light Source

Atomic physics research using an undulator beamline at the Advanced Light Source (ALS).
Date: April 16, 2004
Creator: Berrah, N.
Object Type: Report
System: The UNT Digital Library
Military Medical Care Services: Questions and Answers (open access)

Military Medical Care Services: Questions and Answers

This report includes questions and answers regarding various military medical care services. What is the purpose of the Military Health Services System, who is eligible to receive this care, and what is the DOD pharmacy benefit are among questions asked and answered in this report.
Date: December 16, 2004
Creator: Best, Richard A., Jr.
Object Type: Report
System: The UNT Digital Library
U.S. Intelligence and Policymaking: The Iraq Experience (open access)

U.S. Intelligence and Policymaking: The Iraq Experience

This report explores in broad terms the relationship between the production of intelligence and the making of policy as reflected in the period prior to the war against Iraq in March 2003 and the implications for Congress.
Date: January 16, 2004
Creator: Best, Richard A., Jr.
Object Type: Report
System: The UNT Digital Library
Flat Tax Proposals and Fundamental Tax Reform: An Overview (open access)

Flat Tax Proposals and Fundamental Tax Reform: An Overview

None
Date: July 16, 2004
Creator: Bickley, James M.
Object Type: Report
System: The UNT Digital Library
Focusing Hard X-rays at Current and Future Light Sources for Microscopy and High-Power Applications (open access)

Focusing Hard X-rays at Current and Future Light Sources for Microscopy and High-Power Applications

The field of x-ray optics struggles to develop optical systems with the versatility and sophistication of their visible light counterparts. The advent of fourth-generation light sources will make the struggle even more difficult. Fourth-generation light sources include laser/plasma sources, x-ray Free Electron Lasers (FEL), inverse Compton scattering sources, and the National Ignition Facility. LCLS, (Linac Coherent Light Source), and its European cousin, will be the first of the x-ray FELs. The LCLS, to be built at the Stanford Linear Accelerator Center (SLAC), takes advantage of the existing SLAC linear accelerator to send intense, low emittance electron bunches through a 100 m long undulator structure. Through a process called SASE (Self Amplification of Spontaneous Emission) the electrons interact with the radiation fields they produce while in the undulator causing them to collect into micro bunches that emit coherent light. In the case of the LCLS the coherent radiation will have a wavelength in the x-ray regime, and will be tunable from 1.5 to 15 {angstrom}. The LCLS will deliver x-rays in individual coherent packages lasting < 300 fs, making the LCLS a very important source for studying short time phenomenon and for performing high-resolution x-ray structural analysis of molecular sized systems. …
Date: March 16, 2004
Creator: Bionta, R M
Object Type: Report
System: The UNT Digital Library
Al Qaeda: Statements and Evolving Ideology (open access)

Al Qaeda: Statements and Evolving Ideology

None
Date: November 16, 2004
Creator: Blanchard, Christopher M.
Object Type: Report
System: The UNT Digital Library
Evidence Towards A Quantum Fluid Of Metallic Hydrogen From First-principles Calculations (open access)

Evidence Towards A Quantum Fluid Of Metallic Hydrogen From First-principles Calculations

None
Date: August 16, 2004
Creator: Bonev, S; Schwegler, E; Ogitsu, T & Galli, G
Object Type: Article
System: The UNT Digital Library
Massive Data Pre-Processing with a Cluster Based Approach (open access)

Massive Data Pre-Processing with a Cluster Based Approach

Data coming from complex simulation models reach easily dimensions much greater than available computational resources. Visualization of such data still represents the most intuitive and effective tool for scientific inspection of simulated phenomena. To ease this process several techniques have been adopted mainly concerning the use of hierarchical multi-resolution representations. In this paper we present the implementation of a hierarchical indexing schema for multiresolution data tailored to overwork the computational power of distributed environments.
Date: December 16, 2004
Creator: Borgo, R.; Cignoni, P.; Pascucci, V. & Scopigno, R.
Object Type: Article
System: The UNT Digital Library
Bosnia and Kosovo: U.S. Military Operations (open access)

Bosnia and Kosovo: U.S. Military Operations

None
Date: February 16, 2004
Creator: Bowman, Steve
Object Type: Report
System: The UNT Digital Library
The 2003 Tax Cut: Proposals and Issues (open access)

The 2003 Tax Cut: Proposals and Issues

This report provides a brief description of each tax cut proposal, including major proposals offered by the Democrats in both the House and the Senate during 2003. It discusses the distributional affects of the proposals and potential effects on short and long term economic growth.
Date: July 16, 2004
Creator: Brumbaugh, David L. & Richards, Don C.
Object Type: Report
System: The UNT Digital Library
Fishery, Aquaculture, and Marine Mammal Legislation in the 108th Congress (open access)

Fishery, Aquaculture, and Marine Mammal Legislation in the 108th Congress

This report discusses policy and legislation regarding fish and marine mammals. These animals are important resources in open ocean and nearshore coastal areas. Commercial and sport fishing are jointly managed by the federal government and individual states. Many laws and regulations guide the management of these resources by federal agencies.
Date: December 16, 2004
Creator: Buck, Eugene H.
Object Type: Report
System: The UNT Digital Library
Kinetics of thermal Degradation of Explosive Binders Viton A, Estane, and Kel-F (open access)

Kinetics of thermal Degradation of Explosive Binders Viton A, Estane, and Kel-F

The use of isoconversional, sometimes called model-free, kinetic analysis methods have recently gained favor in the thermal analysis community. Although these methods are very useful and instructive, the conclusion by some that model fitting is a poor approach is largely due to improper use of model fitting, such as fitting a single heating rate or multiple heating rates separately. The current paper shows the ability of model fitting to correlate reaction data over very wide time-temperature regimes for three polymers of interest for formulating high explosives: Estane 5703 P (poly [ester urethane] block copolymer), Viton A (vinylidene-hexafluoropropene copolymer), and Kel-F 800 (vinylidene-chlorotrifluorethene copolymer). The Kel-F required two parallel reactions--one describing an early decomposition process accounting for {approx}1% weight loss and a second autocatalytic reaction describing the remainder of pyrolysis. Essentially no residue was obtained. Viton A and Estane also required two parallel reactions for primary pyrolysis. For Viton A, the first reaction is also a minor, early process, but for Estane, it accounts for 42% of the mass loss. In addition, these to polymers yield 2-3% of residue, and the amount depends on the heating rate. This is an example of a competitive reaction between volatilization and char formation, which …
Date: July 16, 2004
Creator: Burnham, A K & Weese, R K
Object Type: Article
System: The UNT Digital Library
Campaign Financing (open access)

Campaign Financing

This is one report in the series of reports that discuss the campaign finance practices and related issues. Concerns over financing federal elections have become a seemingly perennial aspect of our political system, centered on the enduring issues of high campaign costs and reliance on interest groups for needed campaign funds. The report talks about the today’s paramount issues such as perceived loopholes in current law and the longstanding issues: overall costs, funding sources, and competition.
Date: July 16, 2004
Creator: Cantor, Joseph E.
Object Type: Report
System: The UNT Digital Library