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Analysis of Hydroperoxides in Solid Polyethylene by MAS (13)C NMR and EPR (open access)

Analysis of Hydroperoxides in Solid Polyethylene by MAS (13)C NMR and EPR

{sup 13}C-enriched polyethylene was subjected to {gamma}-irradiation in the presence of air at 25 and 80 C for total doses ranging from 71 to 355 kGy. Significant quantities of hydroperoxides were detected in the 25 C irradiated sample by {sup 13}C magic angle spinning NMR spectroscopy. This method of detection was performed on the solid polymer and required no chemical derivatization or addition of solvent. The chemical stability and subsequent products of the hydroperoxide species were studied by annealing the irradiated samples in air at temperatures ranging from 22 to 110 C. A time-temperature superposition analysis provided an activation energy of 108 kJ/mol for the hydroperoxide decomposition process. The primary products of hydroperoxide decomposition were ketones and secondary alcohols with lesser amounts of acids and esters. EPR measurements suggest that the reactive hydroperoxide species reside in the amorphous phase of polyethylene, consistent with degradation occurring in the amorphous phase.
Date: November 19, 1999
Creator: Assink, Roger A.; Celina, Mathias C.; Dunbar, Timothy D.; Alam, Todd M.; Clough, Roger Lee & Gillen, Kenneth T.
System: The UNT Digital Library
Characterization of a glass-bonded ceramic waste form loaded with U and Pu (open access)

Characterization of a glass-bonded ceramic waste form loaded with U and Pu

This paper presents microscopic characterization of four samples of a ceramic waste form (CWF) developed for disposal of actinide-containing electrorefiner salts. The four samples were prepared to investigate the influence of water content and the Pu:U ratio on CWF microstructure and performance. While the overall phase content is not strongly influenced by either variable, the presence of water in the initial zeolite has a detectable effect on CWF microstructure. It is found to influence the distribution of the major actinide host phase, a (U,Pu)O{sub 2} mixed oxide.
Date: November 19, 1999
Creator: Sinkler, W.; O'Holleran, T. P.; Frank, S. M.; Richmann, M. K. & Johnson, S. G.
System: The UNT Digital Library
Dual-Layer Asymmetric Microporous Silica Membranes (open access)

Dual-Layer Asymmetric Microporous Silica Membranes

We report a novel sol-gel dip-coating process to form dual-layer microporous silica membranes with improved membrane performance and reproducibility. First, we deposit a surfactant-templated silica (STS) intermediate layer on top of a commercial {gamma}-alumina support both to improve its ''surface finish'' and to prevent a subsequently deposited microporous overlayer from penetrating into the support. Second, membranes are processed under clean room conditions to avoid dust contamination and, third, membranes are vacuum-calcined to promote further pore shrinkage and impart surface hydrophobicity. The resulting asymmetric membrane exhibits a gradual change in pore diameter from 50{angstrom} ({gamma}-alumina support layer) to 10-12{angstrom} (STS intermediate layer), and then to 3-4{angstrom} (30nm thick, ultramicroporous silica top-layer). Compared to a single-layer process using only the microporous overlayer, the dual-layer process improves both flux and selectivity. For the industrially important problem of natural gas purification, the combined CO{sub 2} flux [(3{approx} 0.5) x 10{sup {minus}4} cm{sup 3}(STP)/(s{center_dot}cm{sup 2}{center_dot}cm-Hg)] and CO{sub 2}/CH{sub 4} separation factors [200{approx}600] are superior to all previously reported values for separation of a 50/50 (v/v) CO{sub 2}/CH{sub 4} gas mixture. In addition, the membrane selectively separated hydrogen from a simulated reformate from partial oxidation of methanol as evidenced by a high concentration of hydrogen recovery.
Date: November 19, 1999
Creator: Tsai, Chung-Yi; Tam, Siu-Yue; Lu, Yunfeng & Brinker, C. Jeffrey
System: The UNT Digital Library
EXPERIMENTAL RESULTS ON RADIATIVE KAON DECAYS (open access)

EXPERIMENTAL RESULTS ON RADIATIVE KAON DECAYS

This paper reviews the current status of experimental results on radiative kaon decays. Several experiments at BNL, CERN and FNAL have recently or will soon complete data collection; as a result, there are several new results.
Date: November 19, 1999
Creator: Kettell, S.
System: The UNT Digital Library
All hadronic B decay trigger with the CDF silicon vertex tracker (open access)

All hadronic B decay trigger with the CDF silicon vertex tracker

Silicon Vertex tracks are of fundamental importance for reconstructing B meson decays at a hadron collider. The upgraded CDF detector will deploy an online Silicon Vertex Tracker in the level 2 trigger. We have studied how this new device exploits the Tevatron large B meson production to select hadronic B decays fundamental for measuring CP violation and B{sub s} mixing.
Date: October 19, 1999
Creator: Donati, Simone
System: The UNT Digital Library
Correction schemes for the LHC lattice at collision (open access)

Correction schemes for the LHC lattice at collision

Normal form analysis and tracking results show that both normal and skew resonances are driven strongly by the nonlinear fields of the IR quadrupoles. We report here on the possibility of improving the dynamic aperture by compensating these resonances with the use of correctors placed in the IRs. The effectiveness of local correction schemes in the presence of beam-beam interactions is also studied.
Date: October 19, 1999
Creator: Tanaji Sen, N. Gelfand and W. Wan
System: The UNT Digital Library
Fabrication of Machined and Shrink Fitted Impactor; Composite Liners for the Los Alamos HEDP Program (open access)

Fabrication of Machined and Shrink Fitted Impactor; Composite Liners for the Los Alamos HEDP Program

Composite liners have been fabricated for the Los Alamos liner driven HEDP experiments using impactors formed by physical vapor deposition (PVD), electroplating, machining and shrink fitting. Chemical vapor deposition (CVD) has been proposed for some ATLAS liner applications. This paper describes the processes used to fabricate machined and shrink fitted impactors which have been used for copper impactors in 1100 aluminum liners and 6061 T-6 aluminum impactors in 1100 aluminum liners. The most successful processes have been largely empirically developed and rely upon a combination of shrink fitted and light press fitting. The processes used to date will be described along with some considerations for future composite liners requirements in the HEDP Program.
Date: October 19, 1999
Creator: Randolph, B.
System: The UNT Digital Library
Lead-free solder technology transfer from ASE Americas (open access)

Lead-free solder technology transfer from ASE Americas

To safeguard the environmental friendliness of photovoltaics, the PV industry follows a proactive, long-term environmental strategy involving a life-of-cycle approach to prevent environmental damage by its processes and products from cradle to grave. Part of this strategy is to examine substituting lead-based solder on PV modules with other solder alloys. Lead is a toxic metal that, if ingested, can damage the brain, nervous system, liver and kidneys. Lead from solder in electronic products has been found to leach out from municipal waste landfills and municipal incinerator ash was found to be high in lead also because of disposed consumer electronics and batteries. Consequently, there is a movement in Europe and Japan to ban lead altogether from use in electronic products and to restrict the movement across geographical boundaries of waste containing lead. Photovoltaic modules may contain small amounts of regulated materials, which vary from one technology to another. Environmental regulations impact the cost and complexity of dealing with end-of-life PV modules. If they were classified as hazardous according to Federal or State criteria, then special requirements for material handling, disposal, record-keeping and reporting would escalate the cost of decommissioning the modules. Fthenakis showed that several of today's x-Si modules failed …
Date: October 19, 1999
Creator: FTHENAKIS,V.
System: The UNT Digital Library
Mercury and Beyond: Diode-Pumped Solid-State Lasers for Inertial Fusion Energy (open access)

Mercury and Beyond: Diode-Pumped Solid-State Lasers for Inertial Fusion Energy

We have begun building the ''Mercury'' laser system as the first in a series of new generation diode-pumped solid-state lasers for inertial fusion research. Mercury will integrate three key technologies: diodes, crystals, and gas cooling, within a unique laser architecture that is scalable to kilojoule energy levels for fusion energy applications. The primary performance goals include 10% electrical efficiencies at 10 Hz and 100 J with a 2-10 ns pulse length at 1.047 pm wavelength. When completed, Mercury will allow rep-rated target experiments with multiple target chambers for high energy density physics research.
Date: October 19, 1999
Creator: Bibeau, C.; Beach, R. J.; Bayramian, A.; Chanteloup, J. C.; Ebbers, C. A.; Emanuel, M. A. et al.
System: The UNT Digital Library
Multiple Input Feature Sets from Real-Time Color and Range Data for Reliable Tracking (open access)

Multiple Input Feature Sets from Real-Time Color and Range Data for Reliable Tracking

This paper describes a work in progress on using multiple sets of input features for robust real-time object tracking in image sequences. Traditional approaches to tracking relied mostly on segmentation of the intensity data using motion or appearance data. Recent availability of real-time range data allows us to use it as an additional unrivaled source of information. We propose a combination of intensity- and range-based input features. Range data enables localized search for' specific features which improves tracking reliability and speed. Proposed approach was successfully tested for the face and gesture tracking application.
Date: October 19, 1999
Creator: Tsap, L.V. & Goldgof, D.B.
System: The UNT Digital Library
New rare decay results from KTeV (open access)

New rare decay results from KTeV

Recent rare decay results from the KTeV fixed target experiment at Fermilab are shown. Results of searches for the CP violating decay modes K{sub L}{sup 0} {yields} {pi}{sup 0} e{sup +}e{sup -}, K{sub L}{sup 0} {yields} {pi}{sup 0} {mu}{sup +}{mu}{sup -}, and K{sub L}{sup 0} {yields} {pi}{sup 0} {nu}{sup {bar {nu}}} are presented. In addition, new branching ratio measurements of K{sub L}{sup 0} {yields} {pi}{sup 0} {gamma}{gamma}, K{sub L}{sup 0} {yields} e{sup +}e{sup -} {gamma}{gamma}, and the first observation of the decay K{sub L}{sup 0} {yields} {mu}{sup +}{mu}{sup -}{gamma}{gamma} are discussed.
Date: October 19, 1999
Creator: Whitmore, Julie
System: The UNT Digital Library
Application of Ultrasonic Techniques for Brain Injury Diagnosis (open access)

Application of Ultrasonic Techniques for Brain Injury Diagnosis

In this work, we evaluate methods for detecting brain injury using ultrasound. We have used simulations of ultrasonic fields in the head to model the phase distortion of the skull. In addition we present experimental data from the crania of large animals. The experimental data help us understand and evaluate the performance of different transducers in acquiring the backscatter data from the brain through the skull. Both the simulations and acquired data illustrate the superiority of lower-frequency (<= 1 MHz) ultrasonic fields for transcranial acquisition of signals from inside the brain. Additionally, the experimental work shows that the higher-frequency (5 MHz) ultrasound can also be useful in acquiring clean nearfield data to help detect the position of the inner boundary of the skull.
Date: September 19, 1999
Creator: Kasili, P. M.; Mobley, J.; Norton, S. J. & Vo-Dinh, T.
System: The UNT Digital Library
A Case-Study for Life-Long Learning and Adaptation in Cooperative Robot Teams (open access)

A Case-Study for Life-Long Learning and Adaptation in Cooperative Robot Teams

While considerable progress has been made in recent years toward the development of multi-robot teams, much work remains to be done before these teams are used widely in real-world applications. Two particular needs toward this end are the development of mechanisms that enable robot teams to generate cooperative behaviors on their own, and the development of techniques that allow these teams to autonomously adapt their behavior over time as the environment or the robot team changes. This paper proposes the use of the Cooperative Multi-Robot Observation of Multiple Moving Targets (CMOMMT) application as a rich domain for studying the issues of multi-robot learning and adaptation. After discussing the need for learning and adaptation in multi-robot teams, this paper describes the CMOMMT application and its relevance to multi-robot learning. We discuss the results of the previously- developed, hand-generated algorithm for CMOMMT and the potential for learning that was discovered from the hand-generated approach. We then describe the early work that has been done (by us and others) to generate multi- robot learning techniques for the CMOMMT application, as well as our ongoing research to develop approaches that give performance as good, or better, than the hand-generated approach. The ultimate goal of …
Date: September 19, 1999
Creator: Parker, L. E.
System: The UNT Digital Library
A continuous sampling air-ICP for metals emission monitoring (open access)

A continuous sampling air-ICP for metals emission monitoring

An air-inductively coupled plasma (air-ICP) system has been developed for continuous sampling and monitoring of metals as a continuous emission monitor (CEM). The plasma is contained in a metal enclosure to allow reduced-pressure operation. The enclosure and plasma are operated at a pressure slightly less than atmospheric using a Roots blower, so that sample gas is continuously drawn into the plasma. A Teflon sampling chamber, equipped with a sampling pump, is connected to the stack that is to be monitored to isokinetically sample gas from the exhaust line and introduce the sample into the air-ICP. Optical emission from metals in the sampled gas stream is detected and monitored using an acousto-optic tunable filter (AOTF)--echelle spectrometer system. A description of the continuous sampling air-ICP system is given, along with some preliminary laboratory data for continuous monitoring of metals.
Date: September 19, 1999
Creator: Baldwin, D. P.; Zamzow, D. S.; Eckels, D. E. & Miller, G. P.
System: The UNT Digital Library
Crack growth monitoring in harsh environments by electrical potential measurements (open access)

Crack growth monitoring in harsh environments by electrical potential measurements

Electric potential measurement (EPM) technology offers an attractive alternative to conventional nondestructive evaluation (NDE) for monitoring crack growth in harsh environments. Where conventional NDE methods typically require localized human interaction, the EPM technique developed at the Idaho National Engineering and Environmental Laboratory (INEEL) can be operated remotely and automatically. Once a crack-like defect is discovered via conventional means, EPM can be applied to monitor local crack size changes. This is of particular interest in situations where an identified structural defect is not immediately rejectable from a fitness-for-service viewpoint, but due to operational and environmental conditions may grow to an unsafe size with continuing operation. If the location is in a harsh environment where periodic monitoring by normal means is either too costly or not possible, a very expensive repair may be immediately mandated. However, the proposed EPM methodology may offer a unique monitoring capability that would allow for continuing service. INEEL has developed this methodology, supporting equipment, and calibration information to apply EPM in a field environment for just this purpose. Laboratory and pilot scale tests on full-size engineering structures (pressure vessels and piping) have been successfully performed. The technique is applicable to many severe environments because the sensitive equipment …
Date: September 19, 1999
Creator: Lloyd, W. R.; Reuter, W. G. & Weinberg, D. M.
System: The UNT Digital Library
In-Process Detection of Weld Defects Using Laser-Based Ultrasound (open access)

In-Process Detection of Weld Defects Using Laser-Based Ultrasound

Laser-based ultrasonic (LBU) measurement shows great promise for on-line monitoring of weld quality in tailor-welded blanks. Tailor-welded blanks are steel blanks made from plates of differing thickness and/or properties butt-welded together; they are used in automobile manufacturing to produce body, frame, and closure panels. LBU uses a pulsed laser to generate the ultrasound and a continuous wave (CW) laser interferometer to detect the ultrasound at the point of interrogation to perform ultrasonic inspection. LBU enables in-process measurements since there is no sensor contact or near-contact with the workpiece. The authors are using laser-generated plate (Lamb) waves to propagate from one plate into the weld nugget as a means of detecting defects. This paper reports the results of the investigation of a number of inspection architectures based on processing of signals from selected plate waves, which are either reflected from or transmitted through the weld zone. Bayesian parameter estimation and wavelet analysis (both continuous and discrete) have shown that the LBU time-series signal is readily separable into components that provide distinguishing features which describe weld quality. The authors anticipate that, in an on-line industrial application, these measurements can be implemented just downstream from the weld cell. Then the weld quality data …
Date: September 19, 1999
Creator: Bacher, G. D.; Kercel, S. W.; Kisner, R. A.; Klein, M. B. & Pouet, B.
System: The UNT Digital Library
Photoacoustic Measurements in Brain Tissue (open access)

Photoacoustic Measurements in Brain Tissue

In this work, we develop and evaluate the photoacoustic technique for recording spectra of white and gray mammalian brain tissues. In addition to the experimental work, we also discuss the geometric aspects of photoacoustic signal generation using collimated light. Spectra constructed from the peak-to-peak amplitude of the photoacoustic waveforms indicate differences in the two tissue types at wavelengths between 620 and 695 nm. The potential of the technique for non-invasive diagnosis is discussed.
Date: September 19, 1999
Creator: Kasili, P.M.; Mobley, J. & Vo-Dinh, T.
System: The UNT Digital Library
Systematics of Reconstructed Process Facility Criticality Accidents (open access)

Systematics of Reconstructed Process Facility Criticality Accidents

The systematics of the characteristics of twenty-one criticality accidents occurring in nuclear processing facilities of the Russian Federation, the United States, and the United Kingdom are examined. By systematics the authors mean the degree of consistency or agreement between the factual parameters reported for the accidents and the experimentally known conditions for criticality. The twenty-one reported process criticality accidents are not sufficiently well described to justify attempting detailed neutronic modeling. However, results of classic hand calculations confirm the credibility of the reported accident conditions.
Date: September 19, 1999
Creator: Pruvost, N. L.; McLaughlin, T. P. & Monahan, S. P.
System: The UNT Digital Library
Baryogenesis and low energy CP violation (open access)

Baryogenesis and low energy CP violation

CP violation is a crucial component in the creation of the matter - anti matter asymmetry of the universe. An important open question is whether the CP violating phenomena observeable in terrestrial experiments have any relation with those responsible for baryogenesis. We discuss two mechanisms of baryogenesis where this question can be meaningfully posed: ''electroweak baryogenesis'' and ''baryogenesis via leptogenesis''. We show how these scenarios can be constrained by existing and forthcoming experimental data. We present a specific example of both these scenarios where the CP violating phase in the Cabbibo Kobayashi Maskawa matrix is related in a calculable way to the CP violating phase responsible for baryogenesis.
Date: August 19, 1999
Creator: Worah, Mihir P.
System: The UNT Digital Library
Determining a Method to Pressure Test a Novel Type of Glass (open access)

Determining a Method to Pressure Test a Novel Type of Glass

A novel type of glass made with a double ion exchange process is more reliable and fractures in a unique manner compared to glass currently available in the market. The novel glass is unique because it disintegrates into a powder instead of fracturing into shards and splinters, and it fails over a very narrow range of stresses. Potential applications for this glass include using it in removable valves because the powdered glass does not produce obstructions when it breaks, and in other applications that require safety glass. A 20,000-psi MTS pressure system was used to determine the possible techniques for pressure testing the strength of a collection of disk-shaped glass samples. Ordinary (i.e., not ion exchanged) glass samples, 0.962 inches in diameter and 0.07 inches thick, were fractured with linearly increasing pressures to determine the best methods. The best method for testing novel glass samples, with the same size and shape as the ordinary glass, will be implemented. The final results of this ongoing project will be used to ascertain if the novel glass is suitable for potential applications.
Date: August 19, 1999
Creator: Rice, Catherine Diane
System: The UNT Digital Library
Physics design of the DARHT 2nd axis accelerator cell (open access)

Physics design of the DARHT 2nd axis accelerator cell

The next generation of radiographic machines based on induction accelerators require very high brightness electron beams to realize the desired x-ray spot size and intensity. This high brightness must be maintained throughout the beam transport, from source to x-ray converter target. The accelerator for the second-axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility is being designed to accelerate a 4-kA, 2-{micro}s pulse of electrons to 20 MeV. After acceleration, the 2-{micro}s pulse will be chopped into a train of four 50-ns pulses with variable temporal spacing by rapidly deflecting the beam between a beam stop and the final transport section. The short beam pulses will be focused onto an x-ray converter target generating four radiographic pulses within the 2-{micro}s window. Beam instability due to interaction with the accelerator cells can very adversely effect the beam brightness and radiographic pulse quality. This paper describes the various issues considered in the design of the accelerator cell with emphasis on transverse impedance and minimizing beam instabilities.
Date: August 19, 1999
Creator: Chen, Y. J.; Houck, T. L.; Reginato, L. J.; Shang, C. C. & Yu, S. S.
System: The UNT Digital Library
Signal trend identification with fuzzy methods. (open access)

Signal trend identification with fuzzy methods.

A fuzzy-logic-based methodology for on-line signal trend identification is introduced. Although signal trend identification is complicated by the presence of noise, fuzzy logic can help capture important features of on-line signals and classify incoming power plant signals into increasing, decreasing and steady-state trend categories. In order to verify the methodology, a code named PROTREN is developed and tested using plant data. The results indicate that the code is capable of detecting transients accurately, identifying trends reliably, and not misinterpreting a steady-state signal as a transient one.
Date: August 19, 1999
Creator: Reifman, J.; Tsoukalas, L. H.; Wang, X. & Wei, T. Y. C.
System: The UNT Digital Library
Analysis of Radiation-Driven Explosive Flyers (open access)

Analysis of Radiation-Driven Explosive Flyers

There is great interest in being able to use the x-ray output from a Z-pinch for equation of state measurements at extreme conditions. However, the direct x-ray output form the pinch produces a very sharp and rapidly attenuating pressure pulse in target materials. To obtain high quality measurements with this source, a mechanism for generating non-attenuating waves is needed. One possibility involves using the x-ray source to throw a near-normal density intermediate drive at the target, a situation similar to more conventional configurations. To scope out preliminary design parameters, they used the ALEGRA code to simulate a number of different possibilities involving the driver and the gap between it and the target. They used a somewhat idealized radiation source--a main x-ray pulse 30 ns long at its base and peaking at a blackbody temperature of 100 eV. The calculations suggest that a 100-micron aluminum driver with a 90-micron gap will yield a 15-ns-wide non-attenuating pulse with an amplitude of over 250 GPa.
Date: July 19, 1999
Creator: Lawrence, R. J.; Asay, J. R.; Trucano, T. G. & Hall, C. A.
System: The UNT Digital Library
Autonomous, agile micro-satellites and supporting technologies (open access)

Autonomous, agile micro-satellites and supporting technologies

This paper updates the on-going effort at Lawrence Livermore National Laboratory to develop autonomous, agile micro-satellites (MicroSats). The objective of this development effort is to develop MicroSats weighing only a few tens of kilograms, that are able to autonomously perform precision maneuvers and can be used telerobotically in a variety of mission modes. The required capabilities include satellite rendezvous, inspection, proximity-operations, docking, and servicing. The MicroSat carries an integrated proximity-operations sensor-suite incorporating advanced avionics. A new self-pressurizing propulsion system utilizing a miniaturized pump and non-toxic mono-propellant hydrogen peroxide was successfully tested. This system can provide a nominal 25 kg MicroSat with 200-300 m/s delta-v including a warm-gas attitude control system. The avionics is based on the latest PowerPC processor using a CompactPCI bus architecture, which is modular, high-performance and processor-independent. This leverages commercial-off-the-shelf (COTS) technologies and minimizes the effects of future changes in processors. The MicroSat software development environment uses the Vx-Works real-time operating system (RTOS) that provides a rapid development environment for integration of new software modules, allowing early integration and test. We will summarize results of recent integrated ground flight testing of our latest non-toxic pumped propulsion MicroSat testbed vehicle operated on our unique dynamic air-rail.
Date: July 19, 1999
Creator: Breitfeller, E; Dittman, M D; Gaughan, R J; Jones, M S; Kordas, J F; Ledebuhr, A G et al.
System: The UNT Digital Library