Flame Inhibition by Phosphorus-Containing Compounds over a Range of Equivalence Ratios (open access)

Flame Inhibition by Phosphorus-Containing Compounds over a Range of Equivalence Ratios

There is much interest in the combustion mechanism of organophosphorus compounds (OPCs) due to their role as potential halon replacements in fire suppression. A continuing investigation of the inhibition activity of organophosphorus compounds under a range of equivalence ratios was performed experimentally and computationally, as measured by the burning velocity. Updates to a previous mechanism were made by the addition and modification of reactions in the mechanism for a more complete description of the recombination reactions. In this work, the laminar flame speed is measured experimentally and calculated numerically for a premixed propane/air flame, under a range of equivalence ratios, undoped and doped with dimethyl methylphosphonate (DMMP). A detailed investigation of the catalytic cycles involved in the recombination of key flame radicals is made for two equivalence ratios, lean and rich. From this, the importance of different catalytic cycles involved in the lean versus rich case is discussed. Although the importance of certain cycles is different under different stoichiometries, the OPCs are similarly effective across the range, demonstrating the robustness of OPCs as flame suppressants. In addition, it is shown that the phosphorus compounds are most active in the high temperature region of the flame. This may, in part, explain …
Date: March 17, 2004
Creator: Jayaweera, T M; Melius, C F; Pitz, W J; Westbrook, C K; Korobeinichev, O P; Shvartsberg, V M et al.
Object Type: Article
System: The UNT Digital Library
A White Paper Prepared for the OpenMP Architectural Review Board on DMPL: An OpenMP DLL Debugging Interface (open access)

A White Paper Prepared for the OpenMP Architectural Review Board on DMPL: An OpenMP DLL Debugging Interface

OpenMP is a widely adopted standard for threading directives across compiler implementations. The standard is very successful since it provides application writers with a simple, portable programming model for introducing shared memory parallelism into their codes. However, the standards do not address key issues for supporting that programming model in development tools such as debuggers. In this paper, we present DMPL, an OpenMP debugger interface that can be implemented as a dynamically loaded library. DMPL is currently being considered by the OpenMP Tools Committee as a mechanism to bridge the development tool gap in the OpenMP standard.
Date: March 17, 2004
Creator: Cownie, James; DelSignore, John, Jr.; de Supinski, Bronis R. & Warren, Karen
Object Type: Report
System: The UNT Digital Library
Detonation in TATB Hemispheres (open access)

Detonation in TATB Hemispheres

Streak camera breakout and Fabry-Perot interferometer data have been taken on the outer surface of 1.80 g/cm{sup 3} TATB hemispherical boosters initiated by slapper detonators at three temperatures. The slapper causes breakout to occur at 54{sup o} at ambient temperatures and 42{sup o} at -54 C, where the axis of rotation is 0{sup o}. The Fabry velocities may be associated with pressures, and these decrease for large timing delays in breakout seen at the colder temperatures. At room temperature, the Fabry pressures appear constant at all angles. Both fresh and decade-old explosive are tested and no difference is seen. The problem has been modeled with reactive flow. Adjustment of the JWL for temperature makes little difference, but cooling to -54 C decreases the rate constant by 1/6th. The problem was run both at constant density and with density differences using two different codes. The ambient code results show that a density difference is probably there but it cannot be quantified.
Date: March 17, 2004
Creator: Druce, B.; Souers, P. C.; Chow, C.; Roeske, F.; Vitello, P. & Hrousis, C.
Object Type: Article
System: The UNT Digital Library

Reaction-Based Reactive Transport Modeling of Biological Iron(III) Reduction

The summary of this report is: (1) biogenic flux increases as hydrologic residence time decreases; (2) reaction-based reactive transport modeling can capture this effect; (3) solid-phase Fe(III) bioreduction can be sustained at long residence times in natural sediments; and (4) long-term coupled Fe(III)/U(VI) bioreduction can be sustained in natural sediments.
Date: March 17, 2004
Creator: Burgos, Bill
Object Type: Presentation
System: The UNT Digital Library

Geobacter Project

Analysis of the Genetic Potential and Gene Expression of Microbial Communities Involved in the In Situ Bioremediation of Uranium and Harvesting Electrical Energy from Organic Matter The primary goal of this research is to develop conceptual and computational models that can describe the functioning of complex microbial communities involved in microbial processes of interest to the Department of Energy. Microbial Communities to be Investigated: (1) Microbial community associated with the in situ bioremediation of uranium-contaminated groundwater; and (2) Microbial community that is capable of harvesting energy from waste organic matter in the form of electricity.
Date: March 17, 2004
Creator: Lovley, Derek; Coppi, Maddalena; Ciufo, Stacy; Methe, Barbara; Pablo, Pomposiello; Sandler, Steve et al.
Object Type: Presentation
System: The UNT Digital Library

NABIR Field Research Center Oak Ridge, Tennessee

The objective of this report is to understand fundamental biogeochemical processes that would allow for the use of bioremediation approaches for cleaning up, managing, or understanding fate and transport at DOE's contaminated legacy waste sites.
Date: March 17, 2004
Creator: Watson, David
Object Type: Presentation
System: The UNT Digital Library

PNNL/Alabama/ORNL Project Activities and Results

The hypothesis of this report is Mobile radionuclides in low-permeability porous matrix regions of fractured saprolite can be effectively isolated and immobilized by stimulating localized in-situ biological activity in highly-permeable fractured and microfractured zones within the saprolite.
Date: March 17, 2004
Creator: Scheibe, Timothy D.; Roden, Eric E.; Brooks, Scott C. & Zachara, John M.
Object Type: Presentation
System: The UNT Digital Library
Semileptonic decays of D mesons in unquenched lattice QCD (open access)

Semileptonic decays of D mesons in unquenched lattice QCD

We present our preliminary results for semileptonic form factors of D mesons in unquenched lattice QCD. Simulations are carried out with n{sub f} = 2 + 1 dynamical quarks using gauge configurations generated by the MILC collaboration. For the valence quarks, we adopt an improved staggered light quark action and the clover heavy quark action. Our results for D {yields} K and D {yields} {pi} form factors at q{sup 2} = 0 are in agreement with the experimental values.
Date: March 17, 2004
Creator: al., Masataka Okamoto et
Object Type: Article
System: The UNT Digital Library
Electron beam collector with a low back flow (open access)

Electron beam collector with a low back flow

Generation of a DC electron beam in the future Fermilab electron cooler [1] employs an electrostatic acceleration and a beam energy recovery, so that electrons are decelerated from the nominal energy of 4.3 MeV they have in the cooling section to few keV in the collector. Stable performance of this scheme requires a current loss {delta}I below 10 {micro}A at the beam current up to the nominal value of I = 0.5 A. One of sources of the loss is a back flow of secondary electrons from the beam collector. The paper discusses principles and performance of a collector with the low current loss. Electric and magnetic fields in the collectors used in existing electron coolers are axially symmetrical. For practically interesting parameters, such collectors can not provide {delta}I/I<10{sup -4} because of the reversibility of trajectories in the collectors: a secondary electron with the kinetic energy equal to the energy of the primary one can come out of the collector following the trajectory of the ''parent'' electron. The back flow can be dramatically decreased if the reversibility is broken by a transverse magnetic field in the collector cavity. In our case, the field was formed by a system of permanent …
Date: March 17, 2004
Creator: Shemyakin, A.
Object Type: Article
System: The UNT Digital Library
A More improved lattice action for heavy quarks (open access)

A More improved lattice action for heavy quarks

We extend the Fermilab formalism for heavy quarks to develop a more improved action. We give results of matching calculations of the improvement couplings at tree level. Finally, we estimate the discretization errors associated with the new action.
Date: March 17, 2004
Creator: al., M. B. Oktay et
Object Type: Article
System: The UNT Digital Library
A theoretical investigation of mode-locking phenomena in reversed field pinches (open access)

A theoretical investigation of mode-locking phenomena in reversed field pinches

OAK-B135 This paper investigates the formation and breakup of the ''slinky mode'' in an RFP using analytic techniques previously employed to examine mode locking phenomena in tokamaks. The slinky mode is a toroidally localized, coherent interference pattern in the magnetic field which co-rotates with the plasma at the reversal surface. This mode forms, as a result of the nonlinear coupling of multiple m = 1 core tearing modes, via a bifurcation which is similar to that by which toroidally coupled tearing modes lock together in a tokamak. The slinky mode breaks up via a second bifurcation which is similar to that by which toroidally coupled tearing modes in a tokamak unlock. However, the typical m = 1 mode amplitude below which slinky breakup is triggered is much smaller than that above which slinky formation occurs. Analytic expressions for the slinky formation and breakup thresholds are obtained in all regimes of physical interest. The locking of the slinky mode to a static error-field is also investigated analytically. Either the error-field arrests the rotation of the plasma at the reversal surface before the formation of the slinky mode, so that the mode subsequently forms as a non-rotating mode, or the slinky mode …
Date: March 17, 2004
Creator: Fitzpatrick, Richard
Object Type: Report
System: The UNT Digital Library
Top quark physics at the Tevatron (open access)

Top quark physics at the Tevatron

After the successful Run I of the Tevatron (1992-1996),with the top quark discovery, both CDF and D0 experiments were extensively upgraded to meet the challenges of the Tevatron Run II collider. The energy of p{bar p} collisions at the Tevatron was increased from {radical}s = 1.8 TeV to {radical}s = 1.96 TeV. t{bar t} production cross section is expected to increase by a factor of {approx} 30%. Major upgrades in the Tevatron accelerator chain will increase the Run II instantaneous luminosity: the goal is to achieve L = 5 - 20 x 10{sup 31} cm{sup 2}s{sup -1} while the highest luminosity reached up to now (September 2003) is 5.2 x 10{sup 31} cm{sup 2} s{sup -1}. In this paper we will present the top quark properties measured by both CDF and D0 with the first physics-quality data collected during the Run II (March 2002-January 2003). First we will review t{bar t} cross section measurements in the various decay channels; then top quark mass measurements will be presented.
Date: March 17, 2004
Creator: Sidoti, Antonio
Object Type: Article
System: The UNT Digital Library
The D0 level three data acquisition system (open access)

The D0 level three data acquisition system

The DZERO experiment located at Fermilab has recently started RunII with an upgraded detector. The RunII physics program requires the Data Acquisition to readout the detector at a rate of 1 KHz. Events fragments, totaling 250 KB, are readout from approximately 60 front end crates and sent to a particular farm node for Level 3 Trigger processing. A scalable system, capable of complex event routing, has been designed and implemented based on commodity components: VMIC 7750 Single Board Computers for readout, a Cisco 6509 switch for data flow, and close to 100 Linux-based PCs for high-level event filtering.
Date: March 17, 2004
Creator: al., D. Chapin et
Object Type: Article
System: The UNT Digital Library
Coherent phase argument for inflation (open access)

Coherent phase argument for inflation

Cosmologists have developed a phenomenally successful picture of structure in the universe based on the idea that the universe expanded exponentially in its earliest moments. There are three pieces of evidence for this exponential expansion--inflation--from observations of anisotropies in the cosmic microwave background. First, the shape of the primordial spectrum is very similar to that predicted by generic inflation models. Second, the angular scale at which the first acoustic peak appears is consistent with the flat universe predicted by inflation. Here the author describes the third piece of evidence, perhaps the most convincing of all: the phase coherence needed to account for the clear peak/trough structure observed by the WMAP satellite and its predecessors. The author also discusses alternatives to inflation that have been proposed recently and explain how they produce coherent phases.
Date: March 17, 2004
Creator: Dodelson, Scott
Object Type: Article
System: The UNT Digital Library
Commissioning the CDF offline software (open access)

Commissioning the CDF offline software

CDF II is one of the two large collider experiments at Fermilab's Tevatron. Over the past two years we have commissioned the offline computing system. A task that has involved bringing up hundreds of computers and millions of lines of C++ software. This paper reports on this experience, concentrating on the software aspects of the project. We will highlight some of the successes as well as describe some of the work still to do.
Date: March 17, 2004
Creator: Murat, Elizabeth Sexton-Kennedy and Pasha
Object Type: Article
System: The UNT Digital Library
Clad Degradation - FEPs Screening Arguments (open access)

Clad Degradation - FEPs Screening Arguments

The purpose of this report is to document the screening of the cladding degradation features, events, and processes (FEPs) for commercial spent nuclear fuel (CSNF). This report also addresses the effect of some FEPs on both the cladding and the CSNF, DSNF, and HLW waste forms where it was considered appropriate to address the effects on both materials together. This report summarizes the work of others to screen clad degradation FEPs in a manner consistent with, and used in, the Total System Performance Assessment-License Application (TSPA-LA). This document was prepared according to ''Technical Work Plan for Waste Form Degradation Modeling, Testing, and Analyses in Support of LA'' (BSC 2004a [DIRS 167796]).
Date: March 17, 2004
Creator: Siegmann, E.
Object Type: Report
System: The UNT Digital Library
A Synchrotron phase detector for the Fermilab Booster (open access)

A Synchrotron phase detector for the Fermilab Booster

A synchrotron phase detector is diagnostic tool for measuring the relative phase between the accelerating field and the beam. One has been implemented in the Fermilab Booster. This is probably the first time for the Booster that the accelerating voltage seen by the beam can be experimentally determined from the information of the synchrotron phase measurement and the existing total rf accelerating voltage (RFSUM) signal without using the calculated synchrotron phase values.
Date: March 17, 2004
Creator: Yang, Xi & Padilla, Rene D
Object Type: Report
System: The UNT Digital Library
On the Use of 233U-236U Double-Spike for TIMS Measurements of Uranium Isotopes: A Simulation Study (open access)

On the Use of 233U-236U Double-Spike for TIMS Measurements of Uranium Isotopes: A Simulation Study

Synthetic ion beams with instantaneous and temporal characteristics appropriate to thermal ionization mass spectrometry (TIMS) were mathematically generated and analyzed to determine the effects of using a mixed {sup 233}U-{sup 236}U spike (double-spike) in the analysis of uranium isotopes. The instantaneous beam characteristics are the intensities (e.g., counts per second) modeled with a Poisson distribution plus a component of random noise that simulates the detection processes. Several beam intensity and mass fractionation vs. time functions were modeled to simulate a range of sample sizes and the commonly employed methods of data collection. These beam profiles were also generated with different noise levels, and signal-to-noise vs. analytical precision diagrams are presented. Modeling focused on natural uranium, where {sup 238}U/{sup 235}U = 137.88, and on the ability of a given method to determine precisely and accurately small variations in this ratio. Practical limits on precision were determined to be 20-30 ppm, which is consistent with precision seen for other elements by state-of-the-art TIMS. The TIMS total evaporation method was compared directly with the double-spike method. While similar analytical precisions are obtained with either method, the double-spike method of correcting for analytical bias gives more accurate results. The results of a total evaporation …
Date: March 17, 2004
Creator: Williams, R. W.
Object Type: Report
System: The UNT Digital Library
The Kinematics of the Lag-Luminosity Relationship (open access)

The Kinematics of the Lag-Luminosity Relationship

Herein I review the argument that kinematics, i.e. relativistic motions of the emitting source in gamma-ray bursts (GRBs), are the cause of the lag-luminosity relationship observed in bursts with known redshifts.
Date: March 17, 2004
Creator: Salmonson, J D
Object Type: Article
System: The UNT Digital Library
Spectroscopic Properties of Novel Aromatic Metal Clusters: NaM4 (M=Al, Ga, In) and their Cations and Anions (open access)

Spectroscopic Properties of Novel Aromatic Metal Clusters: NaM4 (M=Al, Ga, In) and their Cations and Anions

The ground and several excited states of metal aromatic clusters, namely NaM4 and NaM{sub 4}{sup {+-}} (M=Al, Ga, In) clusters have been investigated by employing complete activespace self-consistent-field (CASSCF) followed by Multi-reference singles and doubles configuration interaction (MRSDCI) computations that included up to 10 million configurations and other methods. The ground states NaM{sub 4}{sup -} of aromatic anions are found to be symmetric C{sub 4v} ({sup 1}A{sub 1}) electronic states with ideal square pyramid geometries. While the ground state of NaIn4 is also predicted to be a symmetric C{sub 4v} ({sup 2}A{sub 1}) square pyramid, the ground state of the NaAl4 cluster is found to have a C{sub 2v} ({sup 2}A{sub 1}) pyramid with a rhombus base and the ground state of NaGa{sub 4} possesses a C{sub 2v} ({sup 2}A{sub 1}) pyramid with a rectangle base. In general these structures exhibit 2 competing geometries, viz., an ideal C{sub 4v} structure and a distorted rhomboidal or rectangular pyramid structure (C{sub 2v}). All of the ground states of the NaM{sub 4}{sup +} (M= Al, Ga, In) cations are computed to be C{sub 2v} ({sup 3}A{sub 2}) pyramids with rhombus bases. The equilibrium geometries, vibrational frequencies, dissociation energies, adiabatic ionization potentials, adiabatic electron …
Date: March 17, 2004
Creator: Balasubramanian, K & Zhao, C
Object Type: Article
System: The UNT Digital Library
Group Theoretical Analysis of Vibrational Modes, Rovibronic Levels and Nuclear Spin Statistics of extended aromatic C48N12 Azafullerene (open access)

Group Theoretical Analysis of Vibrational Modes, Rovibronic Levels and Nuclear Spin Statistics of extended aromatic C48N12 Azafullerene

We have presented a group theoretical analysis of the vibrational modes and rovibronic levels of a novel extended aromatic C{sub 48}N{sub 12} azafullerene. The nuclear spin multiplets and statistical weights of {sup 14}N spin-1 bosons, vibrational and rotational analysis and computed vibrational spectra are provided. We have also predicted the properties of the {sup 3}A{sub u}, {sup 3}E{sub g}, and {sup 3}E{sub u} excited states of C{sub 48}N{sub 12} that lie 1.9 eV above the {sup 1}A{sub g} ground state, and that the {sup 3}E{sub g} and {sup 3}E{sub u} states would undergo Jahn-Teller distortion into chiral structures with no symmetry and an achiral structure with C{sub i} symmetry.
Date: March 17, 2004
Creator: Balasubramanian, K
Object Type: Article
System: The UNT Digital Library
Computational Engineering of the Stability and Optical Gaps of SiC Quantum Dots (open access)

Computational Engineering of the Stability and Optical Gaps of SiC Quantum Dots

None
Date: March 17, 2004
Creator: Reboredo, F; Pizzagalli, L & Galli, G
Object Type: Article
System: The UNT Digital Library
Simulations of CdSe Quantum Dots (open access)

Simulations of CdSe Quantum Dots

None
Date: March 17, 2004
Creator: Puzder, A.; Williamson, A.; Gygi, F. & Galli, G.
Object Type: Article
System: The UNT Digital Library

Field scale evaluation of biostimulation in the near source zone of the former S3 ponds at Oak Ridge

The primary objective of this report is to evaluate the rates and mechanisms of U(VI) reduction by microbial populations.
Date: March 17, 2004
Creator: Criddle, Craig; Fendorf, Scott; Brandt, Craig; Brooks, Scott; Hubbard, Susan; Williams, Ken et al.
Object Type: Presentation
System: The UNT Digital Library