Cleanup Verification Package for the 118-B-6, 108-B Solid Waste Burial Ground (open access)

Cleanup Verification Package for the 118-B-6, 108-B Solid Waste Burial Ground

This cleanup verification package documents completion of remedial action for the 118-B-6, 108-B Solid Waste Burial Ground. The 118-B-6 site consisted of 2 concrete pipes buried vertically in the ground and capped by a concrete pad with steel lids. The site was used for the disposal of wastes from the "metal line" of the P-10 Tritium Separation Project.
Date: June 13, 2006
Creator: Proctor, M. L.
Object Type: Report
System: The UNT Digital Library
Sequencing and Analysis of Neanderthal Genomic DNA (open access)

Sequencing and Analysis of Neanderthal Genomic DNA

Recovery and analysis of multiple Neanderthal autosomalsequences using a metagenomic approach reveals that modern humans andNeanderthals split ~;400,000 years ago, without significant evidence ofsubsequent admixture.
Date: June 13, 2006
Creator: Noonan, James P.; Coop, Graham; Kudaravalli, Sridhar; Smith,Doug; Krause, Johannes; Alessi, Joe et al.
Object Type: Article
System: The UNT Digital Library
Calculation of Neutral Beam Injection into SSPX (open access)

Calculation of Neutral Beam Injection into SSPX

The SSPX spheromak experiment has achieved electron temperatures of 350eV and confinement consistent with closed magnetic surfaces. In addition, there is evidence that the experiment may be up against an operational beta limit for Ohmic heating. To test this barrier, there are firm plans to add two 0.9MW Neutral Beam (NB) sources to the experiment. A question is whether the limit is due to instability. Since the deposited Ohmic power in the core is relatively small the additional power from the beams is sufficient to significantly increase the electron temperature. Here we present results of computations that will support this contention. We have developed a new NB module to calculate the orbits of the injected fast fast-ions. The previous computation made heavy use of tokamak ordering which fails for a tight-aspect-ratio device, where B{sub tor} {approx} B{sub pol}. The model calculates the deposition from the NFREYA package [1]. The neutral from the CX deposition is assumed to be ionized in place, a high-density approximation. The fast ions are then assumed to fill a constant angular momentum orbit. And finally, the fast ions immediately assume the form of a dragged down distribution. Transfer rates are then calculated from this distribution function …
Date: June 13, 2006
Creator: Pearlstein, L. D.; Casper, T. A.; Hill, D. N.; LoDestro, L. L. & McLean, H. S.
Object Type: Article
System: The UNT Digital Library
Support for Whole-Program Analysis and the Verification of the One-Definition Rule in C++ (open access)

Support for Whole-Program Analysis and the Verification of the One-Definition Rule in C++

We present a compact and accurate representation of a whole-program abstract syntax tree, and use it to detect a specific security vulnerability in C++ programs known as a One-Definition Rule (ODR) violation. The ODR states that types and functions appearing in multiple compilation units must be defined identically. However, no current compiler can enforce ODR because doing so requires the ability to see the full application source at once; where ODR is violated, the program is incorrect. Moreover, a lack of ODR enforcement makes a program vulnerable to the so-called VPTR exploit, in which an object's virtual function table is replaced by malicious code. Our representation of the whole program preserves all features of the source for analysis and transformation, and permits a million-line application to fit entirely in the memory of a workstation with 1 GB of RAM.
Date: June 13, 2006
Creator: Quinlan, D; Vuduc, R; Panas, T; Haerdtlein, J & Saebjoernsen, A
Object Type: Article
System: The UNT Digital Library
A Well-Defined, Silica-Supported Tungsten Imido Alkylidene OlefinMetathesis Catalyst (open access)

A Well-Defined, Silica-Supported Tungsten Imido Alkylidene OlefinMetathesis Catalyst

The reaction of [W(=NAr)(=CHtBu)(CH2tBu)2](1; Ar =2,6-iPrC6H3) with a silica partially dehydroxylated at 700oC, SiO2-(700),gives syn-[(_SiO)W(=NAr)(=CHtBu)(CH2tBu)](2) as a major surface species,which was fully characterized by mass balance analysis, IR, NMR, EXAFS,and DFT periodic calculations. Similarly, complex 1 reacts with[(c-C5H9)7Si7O12SiOH]to give [(SiO)W(=NAr)(=CHtBu)(CH2tBu)](2m), whichshows similar spectroscopic properties. Surface complex 2 is a highlyactive propene metathesis catalyst, which can achieve a TON of 16000within 100 h, with only a slow deactivation.
Date: June 13, 2006
Creator: Rhers, Bochra; Salameh, Alain; Baudouin, Anne; Quadrelli, ElsjeA.; Taoufik, Mostafa; Coperet, Christophe et al.
Object Type: Article
System: The UNT Digital Library
Photometric Redshifts in the IRAC Shallow Survey (open access)

Photometric Redshifts in the IRAC Shallow Survey

Accurate photometric redshifts are calculated for nearly 200,000 galaxies to a 4.5 micron flux limit of {approx} 13 {micro}Jy in the 8.5 deg{sup 2} Spitzer/IRAC Shallow survey. Using a hybrid photometric redshift algorithm incorporating both neural-net and template-fitting techniques, calibrated with over 15,000 spectroscopic redshifts, a redshift accuracy of {sigma} = 0.06 (1+z) is achieved for 95% of galaxies at 0 < z < 1.5. The accuracy is {sigma} = 0.12 (1 + z) for 95% of AGN at 0 < z < 3. Redshift probability functions, central to several ongoing studies of the galaxy population, are computed for the full sample. We demonstrate that these functions accurately represent the true redshift probability density, allowing the calculation of valid confidence intervals for all objects. These probability functions have already been used to successfully identify a population of Spitzer-selected high redshift (z > 1) galaxy clusters. We present one such spectroscopically confirmed cluster at <z> = 1.24, ISCS J1434.2+3426. Finally, we present a measurement of the 4.5 {micro}m-selected galaxy redshift distribution.
Date: June 13, 2006
Creator: Brodwin, M.; Brown, M.; Ashby, M.; Bian, C.; Brand, K.; Dey, A. et al.
Object Type: Article
System: The UNT Digital Library
SHOCK INITIATION EXPERIMENTS AND MODELING OF COMPOSITION B AND C-4 (open access)

SHOCK INITIATION EXPERIMENTS AND MODELING OF COMPOSITION B AND C-4

Shock initiation experiments on the explosives Composition B and C-4 were performed to obtain in-situ pressure gauge data for the purpose of determining the Ignition and Growth reactive flow model with proper modeling parameters. A 101 mm diameter propellant driven gas gun was utilized to initiate the explosive charges containing manganin piezoresistive pressure gauge packages embedded in the explosive sample. Experimental data provided new information on the shock velocity versus particle velocity relationship for each of the investigated materials in their respective pressure range. The run-distance-to-detonation points on the Pop-plot for these experiments showed agreement with previously published data, and Ignition and Growth modeling calculations resulted in a good fit to the experimental data. These experimental data were used to determine Ignition and Growth reactive flow model parameters for these explosives. Identical ignition and growth reaction rate parameters were used for C-4 and Composition B, and the Composition B model also included a third reaction rate to simulate the completion of reaction by the TNT component. The Composition B model was then tested on existing short pulse duration, gap test, and projectile impact shock initiation with good results. This Composition B model can be applied to shock initiation scenarios that …
Date: June 13, 2006
Creator: Urtiew, P A; Vandersall, K S; Tarver, C M; Garcia, F & Forbes, J W
Object Type: Article
System: The UNT Digital Library
RECENT STUDIES OF URANIUM AND PLUTONIUM CHEMISTRY IN ALKALINE RADIOACTIVE WASTE SOLUTIONS (open access)

RECENT STUDIES OF URANIUM AND PLUTONIUM CHEMISTRY IN ALKALINE RADIOACTIVE WASTE SOLUTIONS

Solubility studies of uranium and plutonium in a caustic, radioactive Savannah River Site tank waste solution revealed the existence of uranium supersaturation in the as-received sample. Comparison of the results to predictions generated from previously published models for solubility in these waste types revealed that the U model poorly predicts solubility while Pu model predictions are quite consistent with experimental observations. Separate studies using simulated Savannah River Site evaporator feed solution revealed that the known formation of sodium aluminosilicate solids in waste evaporators can promote rapid precipitation of uranium from supersaturated solutions.
Date: June 13, 2006
Creator: King, W; Bill Wilmarth, B; David Hobbs, D & Tommy Edwards, T
Object Type: Article
System: The UNT Digital Library
INTENSE NEUTRINO BEAMS AND LEPTONIC CP VIOLATION. (open access)

INTENSE NEUTRINO BEAMS AND LEPTONIC CP VIOLATION.

Effects of the Leptonic CP violating phase, {delta}, on 3 generation neutrino oscillation rates and asymmetries are discussed. A figure of merit argument is used to show that our ability to measure the phase 6 is rather insensitive to the value of {theta}{sub 13} (for sin{sup 2} 2{theta}{sub 13} {approx}> 0.01) as well as the detector distance (for very long oscillation baselines). Using a study of {nu}{sub {mu}} {yields} {nu}{sub e} oscillations for BNL-Homestake (2540 km) we show that a conventional horn focused wide band neutrino beam generated by an intense 1-2 MW proton source combined with a very large water Cherenkov detector (250-500 kton) should be able to determine {delta} to about {+-}15{sup o} in 5 x 10{sup 7} sec. of running. In addition, such an effort would also measure the other oscillation parameters ({theta}{sub ij}, {Delta}m{sub ij}{sup 2}) with high precision. Similar findings apply to a Fermilab-Homestake (1280 km) baseline. We also briefly discuss features of Superbeams, Neutrino Factories and Beta-Beams.
Date: June 13, 2006
Creator: MARCIANO, W. & PARSA, Z.
Object Type: Article
System: The UNT Digital Library
Modeled Neutron and Charged-Particle Induced Nuclear Reaction Cross Sections for Radiochemistry in the Region of Yttrium, Zirconium, Niobium, and Molybdenum (open access)

Modeled Neutron and Charged-Particle Induced Nuclear Reaction Cross Sections for Radiochemistry in the Region of Yttrium, Zirconium, Niobium, and Molybdenum

We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron, proton, and deuteron induced nuclear reaction cross sections for targets ranging from strontium (Z = 38) to rhodium (Z = 45).
Date: June 13, 2006
Creator: Hoffman, R D; Kelley, K; Dietrich, F S; Bauer, R & Mustafa, M G
Object Type: Report
System: The UNT Digital Library
Fragmentation in Biaxial Tension (open access)

Fragmentation in Biaxial Tension

We have carried out an experiment that places a ductile stainless steel in a state of biaxial tension at a high rate of strain. The loading of the ductile metal spherical cap is performed by the detonation of a high explosive layer with a conforming geometry to expand the metal radially outwards. Simulations of the loading and expansion of the metal predict strain rates that compare well with experimental observations. A high percentage of the HE loaded material was recovered through a soft capture process and characterization of the recovered fragments provided high quality data, including uniform strain prior to failure and fragment size. These data were used with a modified fragmentation model to determine a fragmentation energy.
Date: June 13, 2006
Creator: Campbell, G H; Archbold, G C; Hurricane, O A & Miller, P L
Object Type: Article
System: The UNT Digital Library
The Physics of Edge Resonant Magnetic Perturbations in Hot Tokamak Plasmas (open access)

The Physics of Edge Resonant Magnetic Perturbations in Hot Tokamak Plasmas

None
Date: June 13, 2006
Creator: Evans, T. E.; Burrell, K. H.; Fenstermacher, M. E.; Moyer, R. A.; Osborne, T. H.; Schaffer, M. J. et al.
Object Type: Article
System: The UNT Digital Library
Edge Stability and Transport Control with Resonant Magnetic Perturbations in Collisionless Tokamak Plasmas (open access)

Edge Stability and Transport Control with Resonant Magnetic Perturbations in Collisionless Tokamak Plasmas

A critical issue for fusion plasma research is the erosion of the first wall of the experimental device due to impulsive heating from repetitive edge magneto-hydrodynamic (MHD) instabilities known as 'edge-localized modes' (ELMs). Here, we show that the addition of small resonant magnetic field perturbations completely eliminates ELMs while maintaining a steady-state high-confinement (H-mode) plasma. These perturbations induce a chaotic behavior in the magnetic field lines, which reduces the edge pressure gradient below the ELM instability threshold. The pressure gradient reduction results from a reduction in particle content of the plasma, rather than an increase in the electron thermal transport. This is inconsistent with the predictions of stochastic electron heat transport theory. These results provide a first experimental test of stochastic transport theory in a highly rotating, hot, collisionless plasma and demonstrate a promising solution to the critical issue of controlling edge instabilities in fusion plasma devices.
Date: June 13, 2006
Creator: Evans, T. E.; Moyer, R. A.; Burrell, K. H.; Fenstermacher, M. E.; Joseph, I.; Leonard, A. W. et al.
Object Type: Article
System: The UNT Digital Library
Final Report: Nanoscale Cluster Assembly on Compliant Substrates: A New Route to Epitaxy and Nanosctructure Synthesis (open access)

Final Report: Nanoscale Cluster Assembly on Compliant Substrates: A New Route to Epitaxy and Nanosctructure Synthesis

From our work at the University of Minnesota prior to 2000, we knew that buffer-layer-assisted growth could be used to produce abrupt interfaces where reactions were constrained by the fact that particles derived from tens to millions of atoms were brought into contact with substrates that ranged from GaAs(110) to BiSrCaCuO superconductors. In situ scanning tunneling microscopy had demonstrated that the particles increased in size with the thickness of the buffer layer, and we postulated that buffer desorption somehow ‘tossed the particles around’ so that aggregation was possible. Through access to transmission electron microscopy in the MRL at the University of Illinois, we have been able to determine the distribution of particles delivered to amorphous carbon as a function of buffer thickness, buffer material, particle material, and warm up rate so as to reveal the physics underlying diffusion, aggregation, and coalescence. Significantly, this enhanced understanding makes it possible to design experiments that produce sizes and distributions of nanoparticles of a very wide range of materials.
Date: June 13, 2006
Creator: Weaver, John, H.
Object Type: Report
System: The UNT Digital Library
Spheromak Buildup in SSPX using a Modular Capacitor Bank (open access)

Spheromak Buildup in SSPX using a Modular Capacitor Bank

The Sustained Spheromak Physics Experiment (SSPX) [1] was designed to address both magnetic field generation and confinement. The SSPX produces 1.5-3.5msec, spheromak plasmas with a 0.33m major radius and a minor radius of {approx}0.23m. DC coaxial helicity injection is used to build and sustain the spheromak plasma within the flux conserver. Optimal operation is obtained by flattening the profile of {lambda} = {mu}{sub 0}j/B, consistent with reducing the drive for tearing and other MHD modes, and matching of edge current and bias flux to minimize |{delta}B/B|{sub rms}. With these optimizations, spheromak plasmas with central T{sub e} >350eV and {beta}{sub e} {approx} 5% with toroidal fields of 0.6T [3] have been obtained. If a favorable balance between current drive efficiency and energy confinement can be shown, the spheromak has the potential to yield an attractive magnetic fusion concept [4]. The original SSPX power system consists of two lumped-circuit capacitor banks with fixed circuit parameters. This power system is used to produce an initial fast formation current pulse (10kV, 0.5MJ formation bank), followed by a lower current, 3.5ms flattop sustainment pulse (5kV, 1.5MJ sustainment bank). Experimental results indicate that a variety of injected current pulses, such as a longer sustainment flattop [5], …
Date: June 13, 2006
Creator: Wood, R. D.; McLean, H. S.; Hill, D. N.; Hooper, E. B. & Romero-Talamas, C. A.
Object Type: Article
System: The UNT Digital Library
Hexahedron Projection for Curvilinear Grids (open access)

Hexahedron Projection for Curvilinear Grids

This paper presents a method of dividing into triangle fans the most common projections of hexahedra from curvilinear meshes, so that they can be volume rendered in hardware, with a fragment program for 32-bit floating point compositing.
Date: June 13, 2006
Creator: Max, N.
Object Type: Article
System: The UNT Digital Library