Macroalgae as a Biomass Feedstock: A Preliminary Analysis (open access)

Macroalgae as a Biomass Feedstock: A Preliminary Analysis

A thorough of macroalgae analysis as a biofuels feedstock is warranted due to the size of this biomass resource and the need to consider all potential sources of feedstock to meet current biomass production goals. Understanding how to harness this untapped biomass resource will require additional research and development. A detailed assessment of environmental resources, cultivation and harvesting technology, conversion to fuels, connectivity with existing energy supply chains, and the associated economic and life cycle analyses will facilitate evaluation of this potentially important biomass resource.
Date: September 26, 2010
Creator: Roesijadi, Guritno; Jones, Susanne B.; Snowden-Swan, Lesley J. & Zhu, Yunhua
Object Type: Report
System: The UNT Digital Library
Massless versus Kaluza-Klein gravitons at the LHC (open access)

Massless versus Kaluza-Klein gravitons at the LHC

We show that the LHC will be able to differentiate between a four-dimensional model with quantum gravity at {approx} 1 TeV where the (massless) graviton becomes strongly coupled to standard model particles at 1 TeV and brane world type models with a large extra-dimensional volume and massive Kaluza-Klein gravitons. We estimate that the 14 TeV LHC could put a limit of the order of {approx} 5 TeV on the four dimensional Planck mass in a model independent way.
Date: August 26, 2010
Creator: Calmet, Xavier; U., /Sussex; de Aquino, Priscila; /Louvain U., CP3 /Leuven U.; Rizzo, Thomas G. & /SLAC
Object Type: Article
System: The UNT Digital Library
Measurement of CP violation observables and parameters for the decays $B^{\pm}\to DK^{*\pm}$ (open access)

Measurement of CP violation observables and parameters for the decays $B^{\pm}\to DK^{*\pm}$

We study the decay B{sup -} {yields} DK*{sup -} using a sample of 379 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II B-factory. We perform a 'GLW' analysis where the D meson decays into either a CP-even (CP+) eigenstate (K{sup +}K{sup -}, {pi}{sup +}{pi}{sup -}), CP-odd (CP-) eigenstate (K{sub S}{sup 0}{pi}{sup 0}, K{sub S}{sup 0}{phi}, K{sub S}{sup 0}{omega}) or a non-CP state (K{sup -}{pi}{sup +}). We also analyze D meson decays into K{sup +}{pi}{sup -} from a Cabibbo-favored {bar D}{sup 0} decay or doubly suppressed D{sup 0} decay ('ADS' analysis). We measure observables that are sensitive to the CKM angle {gamma}: the partial-rate charge asymmetries A{sub CP{+-}}, the ratios R{sub CP{+-}} of the B-decay branching fractions in CP{+-} and non-CP decay, the ratio R{sub ADS} of the charge-averaged branching fractions, and the charge asymmetry A{sub ADS} of the ADS decays: A{sub CP+} = 0.09 {+-} 0.13 {+-} 0.06, A{sub CP-} = -0.23 {+-} 0.21 {+-} 0.07, R{sub CP+} = 2.17 {+-} 0.35 {+-} 0.09, R{sub CP-} = 1.03 {+-} 0.27 {+-} 0.13, R{sub ADS} = 0.066 {+-} 0.031 {+-} 0.010, and A{sub ADS} = -0.34 {+-} 0.43 {+-} 0.16, where the first …
Date: August 26, 2010
Creator: Aubert, Bernard; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Object Type: Article
System: The UNT Digital Library
Measurements of the Motion of Plasma Filaments in a Plasma Ball (open access)

Measurements of the Motion of Plasma Filaments in a Plasma Ball

Measurements were made of the motion of the filamentary structures in a plasma ball using high speed cameras and other optical detectors. These filaments traverse the ball radially at ~106 cm/sec at the driving frequency of ~26 kHz, and drift upward through the ball at ~1 cm/sec. Varying the applied high voltage and frequency caused the number, length, and diameter of the filaments to change. A custom plasma ball was constructed to observe the effects of varying gas pressure and species on the filament structures.
Date: January 26, 2010
Creator: M. Campanell, J. Laird, T. Provost, S. Vasquez, S.J. Zweben
Object Type: Report
System: The UNT Digital Library
Mechanical and Thermal Prototype Testing for a Rotatable Collimator for the LHC Phase II Collimation Upgrade (open access)

Mechanical and Thermal Prototype Testing for a Rotatable Collimator for the LHC Phase II Collimation Upgrade

The Phase II upgrade to the LHC collimation system calls for complementing the robust Phase I graphite collimators with high Z, low impedance Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and testing of this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. A prototype collimator jaw has been tested for both mechanical and thermal compliance with the design goals. Thermal expansion bench-top tests are compared to ANSYS simulation results.
Date: August 26, 2010
Creator: Smith, Jeffrey Claiborne; Doyle, Eric; Keller, Lewis; Lundgren, Steven & Markiewicz, Thomas Walter
Object Type: Article
System: The UNT Digital Library
Mechanical Damage, Ignition, and Burn: Experiment, Model Development, and Computer Simulations to Study High-Explosive Violent Response (HEVR) (open access)

Mechanical Damage, Ignition, and Burn: Experiment, Model Development, and Computer Simulations to Study High-Explosive Violent Response (HEVR)

None
Date: January 26, 2010
Creator: Reaugh, J E & Jones, A G
Object Type: Article
System: The UNT Digital Library
Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor (open access)

Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor

None
Date: May 26, 2010
Creator: Auslaender, O.M.
Object Type: Article
System: The UNT Digital Library
'Micromanaging de Sitter holography' (open access)

'Micromanaging de Sitter holography'

We develop tools to engineer de Sitter vacua with semi-holographic duals, using elliptic fibrations and orientifolds to uplift Freund-Rubin compactifications with CFT duals. The dual brane construction is compact and constitutes a microscopic realization of the dS/dS correspondence, realizing d-dimensional de Sitter space as a warped compactification down to (d-1)-dimensional de Sitter gravity coupled to a pair of large-N matter sectors. This provides a parametric microscopic interpretation of the Gibbons-Hawking entropy. We illustrate these ideas with an explicit class of examples in three dimensions, and describe ongoing work on four-dimensional constructions. The Gibbons-Hawking entropy of the de Sitter horizon [1] invites a microscopic interpretation and a holographic formulation of inflating spacetimes. Much progress was made in the analogous problem in black hole physics using special black holes in string theory whose microstates could be reliably counted, such as those analyzed in [2,3]; this led to the AdS/CFT correspondence [4]. In contrast, a microscopic understanding of the entropy of de Sitter space is more difficult for several reasons including its potential dynamical connections to other backgrounds (metastability), the absence of a non-fluctuating timelike boundary, and the absence of supersymmetry. In this paper, we develop a class of de Sitter constructions in …
Date: August 26, 2010
Creator: Dong, Xi; Horn, Bart; /SLAC /Stanford U., Phys. Dept. /Santa Barbara, KITP; Silverstein, Eva; /Santa Barbara, KITP /SLAC /Stanford U., Phys. Dept.; Torroba, Gonzalo et al.
Object Type: Article
System: The UNT Digital Library
Mixing and CP Violation in Charm Meson Decays (open access)

Mixing and CP Violation in Charm Meson Decays

Mixing and CP violation (CPV ) in the neutral D system were first discussed over thirty years ago but mixing was observed for the first time only very recently. Since then, these observations have been confirmed in other experiments and in other D{sup 0} decay modes. Unlike the K, B and B{sub s} systems, for which mixing was observed years earlier, the short distance ({Delta}C = 2) amplitude contributing to mixing in the D system arises from box diagrams with down- rather than up-type quarks in the loops. The d and s components are GIM-suppressed, and the b component is suppressed by the small V{sub ub} CKM coupling. In the standard model (SM), therefore, long range, non-perturbative effects, a coherent sum over intermediate states accessible to both D{sup 0} and {bar D}{sup 0}, are the main contribution to mixing. These are hard to compute reliably, however. The phenomenon of mixing in neutral meson systems has now been observed in all flavours, but only in the past year in the D{sup 0} system. The standard model anticipated that, for the charm sector, the mixing rate would be small, and also that CP violation, either in mixing or in direct decay, would …
Date: August 26, 2010
Creator: Meadows, B & U., /Cincinnati
Object Type: Article
System: The UNT Digital Library
A nanocrystal strain gauge for luminescence detection of mechanical forces (open access)

A nanocrystal strain gauge for luminescence detection of mechanical forces

Local microscale stresses play a crucial role in inhomogeneous mechanical processes from cell motility to material failure. However, it remains difficult to spatially resolve stress at these small length scales. While contact-probe and non-contact based techniques have been used to quantify local mechanical behavior in specific systems with high stiffness or stress and spatial resolution, these methods cannot be used to study a majority of micromechanical systems due to spectroscopic and geometrical constraints. We present here the design and implementation of a luminescent nanocrystal strain gauge, the CdSe/CdS core/shell tetrapod. The tetrapod can be incorporated into many materials, yielding a local stress measurement through optical fluorescence spectroscopy of the electronically confined CdSe core states. The stress response of the tetrapod is calibrated and utilized to study mechanical behavior in single polymer fibers. We expect that tetrapods can be used to investigate local stresses in many other mechanical systems.
Date: July 26, 2010
Creator: Choi, Charina; Koski, Kristie; Olson, Andrew & Alivisatos, Paul
Object Type: Article
System: The UNT Digital Library
Near infrared spectral imaging of explosives using a tunable laser source (open access)

Near infrared spectral imaging of explosives using a tunable laser source

Diffuse reflectance near infrared hyperspectral imaging is an important analytical tool for a wide variety of industries, including agriculture consumer products, chemical and pharmaceutical development and production. Using this technique as a method for the standoff detection of explosive particles is presented and discussed. The detection of the particles is based on the diffuse reflectance of light from the particle in the near infrared wavelength range where CH, NH, OH vibrational overtones and combination bands are prominent. The imaging system is a NIR focal plane array camera with a tunable OPO/laser system as the illumination source. The OPO is programmed to scan over a wide spectral range in the NIR and the camera is synchronized to record the light reflected from the target for each wavelength. The spectral resolution of this system is significantly higher than that of hyperspectral systems that incorporate filters or dispersive elements. The data acquisition is very fast and the entire hyperspectral cube can be collected in seconds. A comparison of data collected with the OPO system to data obtained with a broadband light source with LCTF filters is presented.
Date: March 26, 2010
Creator: Klunder, G. L.; Margalith, E. & Nguyen, L. K.
Object Type: Article
System: The UNT Digital Library
No Prejudice in Space (open access)

No Prejudice in Space

We present a summary of recent results obtained from a scan of the 19-dimensional parameter space of the pMSSM and its implications for dark matter searches. We have generated a large set of points in parameter space (which we call 'models') for the 19-parameter CP-conserving pMSSM, where MFV has been assumed. We subjected these models to numerous experimental and theoretical constraints to obtain a set of {approx}68 K models which are consistent with existing data. We attempted to be somewhat conservative in our implementation of these constraints; in particular we only demanded that the relic density of the LSP not be greater than the measured value of {Omega}H{sup 2} for non-baryonic dark matter, rather than assuming that the LSP must account for the entire observed relic density. Examining the properties of the neutralinos in these models, we find that many are relatively pure gauge eigenstates with Higgsinos being the most common, followed by Winos. The relative prevalence of Higgsino and Wino LSPs leads many of our models to have a chargino as nLSP, often with a relatively small mass splitting between this nLSP and the LSP; this has important consequences in both collider and astroparticle phenomenology. We find that, in …
Date: August 26, 2010
Creator: Cotta, R. C.; Gainer, J. S.; Hewett, J. L. & Rizzo, T. G.
Object Type: Article
System: The UNT Digital Library
Nuclear Material Attractiveness: An Assessment of Material From Phwr's in a Closed Thorium Fuel Cycle (open access)

Nuclear Material Attractiveness: An Assessment of Material From Phwr's in a Closed Thorium Fuel Cycle

This paper examines the attractiveness of material mixtures containing special nuclear materials (SNM) associated with reprocessing and the thorium-based LWR fuel cycle. This paper expands upon the results from earlier studies that examined the attractiveness of SNM associated with the reprocessing of spent light water reactor (LWR) fuel by various reprocessing schemes and the recycle of plutonium as a mixed oxide (MOX) fuel in LWR. This study shows that {sup 233}U that is produced in thorium-based fuel cycles is very attractive for weapons use. Consistent with other studies, these results also show that all fuel cycles examined to date need to be rigorously safeguarded and provided moderate to high levels of physical protection. These studies were performed at the request of the United States Department of Energy (DOE), and are based on the calculation of 'attractiveness levels' that has been couched in terms chosen for consistency with those normally used for nuclear materials in DOE nuclear facilities. The methodology and key findings will be presented.
Date: April 26, 2010
Creator: Sleaford, B. W.; Collins, B. A.; Ebbinghaus, B. B.; Bathke, C. G.; Prichard, A. W.; Wallace, R. K. et al.
Object Type: Article
System: The UNT Digital Library
Observation of the decay B0bar -> LambdaC antiproton pi0 (open access)

Observation of the decay B0bar -> LambdaC antiproton pi0

In a sample of 467 million B{bar B} pairs collected with the BABAR detector at the PEP-II collider at SLAC we have observed the decay {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup 0} and measured the branching fraction to be (1.94 {+-} 0.17 {+-} 0.14 {+-} 0.50) x 10{sup -4}, where the uncertainties are statistical, systematic, and the uncertainty on the {Lambda}{sub c}{sup +} {yields} pK{sup -}{pi}{sup +} branching fraction, respectively. We determine an upper limit of 1.5 x 10{sup -6} at 90% C.L. for the product branching fraction {Beta}({bar B}{sup 0} {yields} {Sigma}{sub c}{sup +}(2455){bar p}) x {Beta}({Lambda}{sub c}{sup +} {yields} pK{sup -}{pi}{sup +}). Furthermore, we observe an enhancement at the threshold of the invariant mass of the baryon-antibaryon pair.
Date: August 26, 2010
Creator: Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Object Type: Article
System: The UNT Digital Library
Observation of the three-body rare decay B-> J/psi phi K (open access)

Observation of the three-body rare decay B-> J/psi phi K

The authors report the study of the B meson decays B{sup {+-}} {yields} J/{psi}{phi}K{sup {+-}}, B{sup 0} {yields} J/{psi}{phi}K{sup 0} using 433 million of B{bar B} events collected at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II e{sup +}e{sup -} asymmetric-energy collider. They obtain the branching fraction measurements: {Beta}(B{sup {+-}} {yields} J{psi}{phi}K{sup {+-}}) = (5.6 {+-} 0.9(stat) {+-} 0.3(sys)) x 10{sup -5}, {Beta}(B{sup {+-}} {yields} J{psi}{phi}K{sup 0}) = (5.4 {+-} 1.2(stat) {+-} 0.4(sys)) x 10{sup -5}.
Date: August 26, 2010
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
On the Physical Relevance of the Study of gamma* gamma -> pi pi at small t and large Q2 (open access)

On the Physical Relevance of the Study of gamma* gamma -> pi pi at small t and large Q2

We discuss the relevance of a dedicated measurement of exclusive production of a pair of neutral pions in a hard {gamma}*{gamma} scattering at small momentum transfer. In this case, the virtuality of one photon provides us with a hard scale in the process, enabling us to perform a QCD calculation of this reaction rate using the concept of Transition Distribution Amplitudes (TDA). Those are related by sum rules to the pion axial form factor F{sub A}{sup {pi}} and, as a direct consequence, a cross-section measurement of this process at intense beam electron-positron colliders such as CLEO, KEK-B and PEP-II, or Super-B would provide us with a unique measurement of the neutral pion axial form factor F{sub A}{sup {pi}0} at small scale. We believe that our models for the photon to meson transition distribution amplitudes are sufficiently constrained to give reasonable orders of magnitude for the estimated cross sections. Cross sections are large enough for quantitative studies to be performed at high luminosity e{sup +}e{sup -} colliders. After verifying the scaling and the {phi} independence of the cross section, one should be able to measure these new hadronic matrix elements, and thus open a new gate to the understanding of the …
Date: August 26, 2010
Creator: Lansberg, J. P.; Pire, B. & Szymanowski, L.
Object Type: Article
System: The UNT Digital Library
One Bacterial Cell, One Complete Genome (open access)

One Bacterial Cell, One Complete Genome

While the bulk of the finished microbial genomes sequenced to date are derived from cultured bacterial and archaeal representatives, the vast majority of microorganisms elude current culturing attempts, severely limiting the ability to recover complete or even partial genomes from these environmental species. Single cell genomics is a novel culture-independent approach, which enables access to the genetic material of an individual cell. No single cell genome has to our knowledge been closed and finished to date. Here we report the completed genome from an uncultured single cell of Candidatus Sulcia muelleri DMIN. Digital PCR on single symbiont cells isolated from the bacteriome of the green sharpshooter Draeculacephala minerva bacteriome allowed us to assess that this bacteria is polyploid with genome copies ranging from approximately 200?900 per cell, making it a most suitable target for single cell finishing efforts. For single cell shotgun sequencing, an individual Sulcia cell was isolated and whole genome amplified by multiple displacement amplification (MDA). Sanger-based finishing methods allowed us to close the genome. To verify the correctness of our single cell genome and exclude MDA-derived artifacts, we independently shotgun sequenced and assembled the Sulcia genome from pooled bacteriomes using a metagenomic approach, yielding a nearly identical …
Date: April 26, 2010
Creator: Woyke, Tanja; Tighe, Damon; Mavrommatis, Konstantinos; Clum, Alicia; Copeland, Alex; Schackwitz, Wendy et al.
Object Type: Article
System: The UNT Digital Library
Oxygen-Fired CO{sub 2} Recycle for Application to Direct CO{sub 2} Capture form Coal-Fired Power Plants (open access)

Oxygen-Fired CO{sub 2} Recycle for Application to Direct CO{sub 2} Capture form Coal-Fired Power Plants

The Southern Research/Southern Company 1 MWth Pilot-Scale Coal-Fired Test Facility was successfully retrofit to fire in either the traditional air-fired mode or with 100% oxygen and recycled flue gas, with a fully integrated feedback and control system, including oxygen and recycled flue gas modulation during startup, transfer, and shutdown, safety and operational interlocks, and data acquisition. A MAXON Staged Oxygen Burner for Oxy-Coal Applications produced a stable flame over a significant range of firing turn-down, staging, and while firing five different U.S. coal types. The MAXON burner design produces lower flame temperatures than for air firing, which will enable (A) Safe operation, (B) Reduction of recycle flow without concern about furnace flame temperatures, and (C) May likely be affective at reducing slagging and fouling in the boiler and super heater at full-scale Power Plants. A CFD model of the Oxy-fired Combustion Research Facility (OCRF) was used to predict the flame geometry and temperatures in the OCRF and make a comparison with the air-fired case. The model predictions were consistent with the experimental data in showing that the MAXON burner fired with oxygen produced lower flame temperatures than the air-fired burner while firing with air.
Date: September 26, 2010
Creator: Gale, Thomas
Object Type: Report
System: The UNT Digital Library
P1-Marx Modulator for the ILC (open access)

P1-Marx Modulator for the ILC

A first generation prototype, P1, Marx-topology klystron modulator has been developed at the SLAC National Accelerator Laboratory for the International Linear Collider (ILC) project. It is envisioned as a lower cost, smaller footprint, and higher reliability alternative to the present, bouncer-topology, baseline design. The application requires 120 kV (+/-0.5%), 140 A, 1.6 ms pulses at a rate of 5 Hz. The Marx constructs the high voltage pulse by combining, in series, a number of lower voltage cells. The Marx employs solid state elements; IGBTs and diodes, to control the charge, discharge and isolation of the cells. Active compensation of the output is used to achieve the voltage regulation while minimizing the stored energy. The P1-Marx has been integrated into a test stand with a 10 MW L-band klystron, where each is undergoing life testing. A review of the P1-Marx design and its operational history in the L-band test stand are presented.
Date: August 26, 2010
Creator: Beukers, T.; Burkhart, C.; Kemp, M.; Larsen, R.; Nguyen, M.; Olsen, J. et al.
Object Type: Article
System: The UNT Digital Library
Parity Violation in Composite Inelastic Dark Matter Models (open access)

Parity Violation in Composite Inelastic Dark Matter Models

Recent experimental results indicate that the dark matter sector may have a non-minimal structure with a spectrum of states and interactions. Inelastic scattering has received particular attention in light of DAMA's annual modulation signal. Composite inelastic dark matter (CiDM) provides a dynamical origin for the mass splittings in inelastic dark matter models. We show that higher dimensional operators in the CiDM Lagrangian lead to an admixture of inelastic and elastic scattering in the presence of parity violation. This scenario is consistent with direct detection experiments, even when parity violation is nearly maximal. We present an effective field theory description of such models and discuss the constraints from direct detection experiments. The CiDM model with parity violation has non-trivial phenomenology because of the multiple scattering channels that are allowed.
Date: August 26, 2010
Creator: Lisanti, Mariangela & Wacker, Jay G.
Object Type: Article
System: The UNT Digital Library
PICMG xTCA Standards Extensions for Physics: New Developments & Future Plans (open access)

PICMG xTCA Standards Extensions for Physics: New Developments & Future Plans

After several years of planning and workshop meetings, a decision was reached in late 2008 to organize PICMG xTCA for Physics Technical Subcommittees to extend the ATCA and MTCA telecom standards for enhanced system performance, availability and interoperability for physics controls and applications hardware and software. Since formation in May-June 2009, the Hardware Technical Subcommittee has developed a number of ATCA, ARTM, AMC, MTCA and RTM extensions to be completed in mid-to-late 2010. The Software Technical Subcommittee is developing guidelines to promote interoperability of modules designed by industry and laboratories, in particular focusing on middleware and generic application interfaces such as Standard Process Model, Standard Device Model and Standard Hardware API. The paper describes the prototype design work completed by the lab-industry partners to date, the timeline for hardware releases to PICMG for approval, and the status of the software guidelines roadmap. The paper also briefly summarizes the program of the 4th xTCA for Physics Workshop immediately preceding the RT2010 Conference. he case for developing ATCA and MicroTCA (xTCA) specification extensions for physics has been covered in several previous papers. Briefly, ATCA and MicroTCA is the first all-serial communication platform available to the physics community to support both massively complex …
Date: August 26, 2010
Creator: Larsen, R.S.
Object Type: Article
System: The UNT Digital Library
Polar Kerr Effect as Probe for Time-Reversal Symmetry Breaking in Unconventional Superconductors (open access)

Polar Kerr Effect as Probe for Time-Reversal Symmetry Breaking in Unconventional Superconductors

The search for broken time reversal symmetry (TRSB) in unconventional superconductors intensified in the past year as more systems have been predicted to possess such a state. Following our pioneering study of TRSB states in Sr{sub 2}RuO{sub 4} using magneto-optic probes, we embarked on a systematic study of several other of these candidate systems. The primary instrument for our studies is the Sagnac magneto-optic interferometer, which we recently developed. This instrument can measure magneto-optic Faraday or Kerr effects with an unprecedented sensitivity of 10 nanoradians at temperatures as low as 100 mK. In this paper we review our recent studies of TRSB in several systems, emphasizing the study of the pseudogap state of high temperature superconductors and the inverse proximity effect in superconductor/ferromagnet proximity structures.
Date: May 26, 2010
Creator: Kapitulnik, A.
Object Type: Article
System: The UNT Digital Library
POTENTIAL FOR STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS CONTAINING HIGHLY CAUSTIC SOLUTIONS (open access)

POTENTIAL FOR STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS CONTAINING HIGHLY CAUSTIC SOLUTIONS

The evaporator recycle streams of nuclear waste tanks may contain waste in a chemistry and temperature regime that exceeds the current corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history found that two of these A537 carbon steel tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved tanks of similar construction. Therefore, it appears that the efficacy of stress relief of welding residual stress is the primary corrosion-limiting mechanism. The objective of this experimental program is to test A537 carbon steel small scale welded U-bend specimens and large welded plates (30.48 x 30.38 x 2.54 cm) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 C). These conditions simulate worst-case situations in these nuclear waste tanks. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test was completed after 12 weeks of …
Date: April 26, 2010
Creator: Lam, P.; Stripling, C.; Fisher, D. & Elder, J.
Object Type: Article
System: The UNT Digital Library
Predicting laser-induced bulk damage and conditioning for deuterated potassium di-hydrogen phosphate crystals using ADM (absorption distribution model) (open access)

Predicting laser-induced bulk damage and conditioning for deuterated potassium di-hydrogen phosphate crystals using ADM (absorption distribution model)

We present an empirical model that describes the experimentally observed laser-induced bulk damage and conditioning behavior in deuterated Potassium dihydrogen Phosphate (DKDP) crystals in a self-consistent way. The model expands on an existing nanoabsorber precursor model and the multi-step absorption mechanism to include two populations of absorbing defects, one with linear absorption and another with nonlinear absorption. We show that this model connects previously uncorrelated small-beam damage initiation probability data to large-beam damage density measurements over a range of ns pulse widths relevant to ICF lasers such as the National Ignition Facility (NIF). In addition, this work predicts the damage behavior of laser-conditioned DKDP and explains the upper limit to the laser conditioning effect. The ADM model has been successfully used during the commissioning and early operation of the NIF.
Date: February 26, 2010
Creator: Liao, Z. M.; Spaeth, M. L.; Manes, K.; Adams, J. J. & Carr, C. W.
Object Type: Article
System: The UNT Digital Library