Stability of Stationary Solutions of the Multifrequency Radiation Diffusion Equations (open access)

Stability of Stationary Solutions of the Multifrequency Radiation Diffusion Equations

A nondimensional model of the multifrequency radiation diffusion equation is derived. A single material, ideal gas, equation of state is assumed. Opacities are proportional to the inverse of the cube of the frequency. Inclusion of stimulated emission implies a Wien spectrum for the radiation source function. It is shown that the solutions are uniformly bounded in time and that stationary solutions are stable. The spatially independent solutions are asymptotically stable, while the spatially dependent solutions of the linearized equations approach zero.
Date: January 20, 2004
Creator: Hald, O H & Shestakov, A I
Object Type: Article
System: The UNT Digital Library
Position Estimation of Transceivers in Communication Networks (open access)

Position Estimation of Transceivers in Communication Networks

With rapid developments in wireless sensor networks, there is a growing need for transceiver position estimation independent of GPS, which may not be available in indoor networks. Our approach is to use range estimates from time-of-flight (TOF) measurements, a technique well suited to large bandwidth physical links, such as in ultra-wideband (UWB) systems. In our UWB systems, pulse duration less than 200 psecs can easily be resolved to less than a foot. Assuming an encoded UWB physical layer, we first test positioning accuracy using simulations. We are interested in sensitivity to range errors and the required number of ranging nodes, and we show that in a high-precision environment, such as UWB, the optimal number of transmitters is four. Four transmitters with {+-}20ft. range error can locate a receiver to within one or two feet. We then implement these algorithms on an 802.11 wireless network and demonstrate the ability to locate a network access point to approximately 20 feet.
Date: January 20, 2004
Creator: Dowla, F. & Kent, C.
Object Type: Article
System: The UNT Digital Library
High-resolution crystal spectrometer for the 10-60 (angstrom) EUV region (open access)

High-resolution crystal spectrometer for the 10-60 (angstrom) EUV region

A vacuum crystal spectrometer with nominal resolving power approaching 1000 is described for measuring emission lines with wavelength in the extreme ultraviolet region up to 60 Angstroms. The instrument utilizes a flat octadecyl hydrogen maleate (OHM) crystal and a thin-window 1-D position-sensitive gas proportional detector. This detector employs a 1 {micro}m-thick 100 x8 mm{sup 2} aluminized polyimide window and operates at one atmosphere pressure. The spectrometer has been implemented on the Livermore electron beam ion traps. The performance of the instrument is illustrated in measurements of the newly discovered magnetic field-sensitive line in Ar{sup 8+}.
Date: February 20, 2004
Creator: Beiersdorfer, P; Brown, G V; Goddard, R & Wargelin, B J
Object Type: Article
System: The UNT Digital Library
NUCLEAR-OPTICAL CONVERTERS FOR NEUTRON DETECTION (open access)

NUCLEAR-OPTICAL CONVERTERS FOR NEUTRON DETECTION

Nuclear-optical converters (NOC) are fission chambers based upon fission fragment energy conversion to optical radiation in gas luminescent media. The All-Russia Scientific Research Institute of Experimental Physics (VNIIEF) has demonstrated that it is possible to construct nuclear-optical converters with characteristics appropriate for a wide-range of measuring applications including neutron detection in nuclear power plants. These detectors may be used a number of different modes: pulse count, luminescent (equivalent to current mode in ionization detectors), and lasing (essentially a neutron switch). NOCs offer a number of potential advantages over ionization detectors. The detectors require no power supply. Signals are transmitted via light-pipe or fiber optics rather than insulated electrical cable. The detectors are less sensitive to gamma radiation. NOC can produce large signals, obviating the need for pre-amplifiers near the detector. It is possible to construct a single detector which measures flux at many discrete points and at the same time provides total flux along a line containing these discrete points. This paper describes the construction and testing of NOC at VNIIEF; the range of characteristics thought to be reasonably attainable with nuclear-optical converters, and possible applications to nuclear power plant instrumentation.
Date: August 20, 2004
Creator: Sinyanskii, A A; Melnikov, S P; Dovbysh, L E & Johnson, G L
Object Type: Article
System: The UNT Digital Library
Sorption and Transport of Iodine Species in Sediments from the Savannah River and Hanford Sites (open access)

Sorption and Transport of Iodine Species in Sediments from the Savannah River and Hanford Sites

Iodine is an important element in studies of environmental protection and human health, global-scale hydrologic processes and nuclear nonproliferation. Biogeochemical cycling of iodine is complex, because iodine occurs in multiple oxidation states and as inorganic and organic species that may be hydrophilic, atmophilic, and biophilic. In this study, we focused on the sorption and transport behavior of iodine species (iodide, iodate, and 4-iodoaniline) in sediments collected at the Savannah River and Hanford Sites, where anthropogenic {sup 129}I from prior nuclear fuel processing activities poses an environmental risk. We conducted both column and batch experiments to investigate the sorption and transport behavior of iodine, and the sediments we examined exhibit a wide range in organic matter, clay mineralogy, soil pH, and texture. The results of our experiments illustrate complex behavior with various processes occurring, including iodate reduction, irreversible retention or mass loss of iodide, and rate-limited and nonlinear sorption. There was an appreciable iodate reduction to iodide, presumably mediated by the structural Fe(II) in some clay minerals; therefore, careful attention must be given to potential interconversion among species when interpreting the biogeochemical behavior of iodine in the environment. The different iodine species exhibited dramatically different sorption and transport behavior in three …
Date: May 20, 2004
Creator: Hu, Q; Zhao, P; Moran, J & Seaman, J
Object Type: Article
System: The UNT Digital Library
Salient Points for Tracking Moving Objects in Video (open access)

Salient Points for Tracking Moving Objects in Video

Detection and tracking of moving objects is important in the analysis of video data. One approach is to maintain a background model of the scene and subtract it from each frame to detect the moving objects which can then be tracked using Kalman or particle filters. In this paper, we consider simple techniques based on salient points to identify moving objects which are tracked using motion correspondence. We focus on video with a large field of view, such as a traffic intersection with several buildings nearby. Such scenes can contain several salient points, not all of which move between frames. Using public domain video and two types of salient points, we consider how to make these techniques computationally efficient for detection and tracking. Our early results indicate that salient regions obtained using the Lowe keypoints algorithm and the Scale-Saliency algorithm can be used successfully to track vehicles in moderate resolution video.
Date: December 20, 2004
Creator: Kamath, C; Gezahegne, A; Newsam, S & Roberts, G M
Object Type: Article
System: The UNT Digital Library
Vacuum Drying of Actual Transuranic Waste from Hanford Tanks (open access)

Vacuum Drying of Actual Transuranic Waste from Hanford Tanks

Composites of sludge from Tanks 241-B-203, 241-T-203, 241 T 204, and 241-T-110 at the Hanford Site were prepared at the Hanford 222-S Laboratory from core samples retrieved from these tanks. These tank composites may not be representative of the entire contents of the tank but provide some indication of the properties of the waste within these underground storage tanks. The composite samples were diluted with water at the Radiochemical Processing Laboratory at Pacific Northwest National Laboratory to represent the slurries that are expected to be received from tank retrieval operations and processed to produce a final waste stream. The dilutions were vacuum dried at 60 C and 26 in. of mercury ({approx} 100 torr). Semi-quantitative measurements of stickiness and cohesive strength were made on these dilutions as a function of drying time. Mass loss as a function of drying time and total solids concentration of the initial dilution and at the conclusion of drying were also measured. Visual observations of the sludge were recorded throughout the drying process.
Date: May 20, 2004
Creator: Tingey, Joel M.
Object Type: Report
System: The UNT Digital Library
Simulation of Chamber Transport for Heavy-Ion Fusion Drivers (open access)

Simulation of Chamber Transport for Heavy-Ion Fusion Drivers

The heavy-ion fusion (HIF) community recently developed a power-plant design that meets the various requirements of accelerators, final focus, chamber transport, and targets. The point design is intended to minimize physics risk and is certainly not optimal for the cost of electricity. Recent chamber-transport simulations, however, indicate that changes in the beam ion species, the convergence angle, and the emittance might allow more-economical designs.
Date: May 20, 2004
Creator: Sharp, W. M.; Callahan, D. A.; Tabak, M.; Yu, S. S.; Peterson, P. F.; Rose, D. V. et al.
Object Type: Article
System: The UNT Digital Library
Yb:S-FAP Lasers (open access)

Yb:S-FAP Lasers

It has recently been reported that several high power, diode-pumped laser systems have been developed based on crystals of Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F]. The Mercury Laser, at Lawrence Livermore National Laboratory, is the most prominent system using Yb:S-FAP and is currently producing 23J at 5 Hz in a 15 nsec pulse, based on partial activation of the system. In addition, a regenerative amplifier is being developed at Waseda University in Japan and has produced greater than 12 mJ with high beam quality at 50Hz repetition rate. Q-peak has demonstrated 16 mJ of maximum energy/output pulse in a multi-pass, diode side-pumped amplifier and ELSA in France is implementing Yb:S-FAP in a 985 nm pump for an EDFA, producing 250 mW. Growth of high optical quality crystals of Yb:S-FAP is a challenge due to multiple crystalline defects. However, at this time, a growth process has been developed to produce high quality 3.5 cm diameter Yb:S-FAP crystals and a process is under development for producing 6.5 cm diameter crystals.
Date: January 20, 2004
Creator: Schaffers, K I
Object Type: Article
System: The UNT Digital Library
Structural Characterization and Lifetime Stability of Mo/Y Extreme Ultraviolet Multilayer Mirrors (open access)

Structural Characterization and Lifetime Stability of Mo/Y Extreme Ultraviolet Multilayer Mirrors

We observe a dramatic dependence of the extreme ultraviolet (EUV) reflectivity of Mo/Y multilayers on the oxygen content of yttrium. This is explained by a change in microstructure, increase in roughness of the Y layers and not by an increase in absorption due to oxygen in Y layers. We find best reflectivity of 38.4% is achieved with an oxygen content of 25%, which reduces to 32.6% and 29.6% for multilayers manufactured from oxygen free yttrium and 39%-oxygen yttrium, respectively. These results highlight the importance of experimentally determined optical constants as well as interface roughness in multilayer calculations. In addition, lifetime stability of Mo/Y multilayers with different capping layers was monitored for one year. The molybdenum- and palladium-capped samples exhibited low surface roughness and about 4% relative reflectivity loss in one year. The relative reflectivity loss on yttrium-capped sample (yttrium with 39% oxygen) was about 8%. However, the reflectivity loss in all three capping layers occurred within the first 100 days after the deposition and the reflectivity remained stable afterwards.
Date: May 20, 2004
Creator: Kjornrattanawanich, B & Bajt, S
Object Type: Article
System: The UNT Digital Library
Lipid Membrane Composition Analyzed by Multi-isotope Imaging Mass Spectrometry (open access)

Lipid Membrane Composition Analyzed by Multi-isotope Imaging Mass Spectrometry

The lateral organization of lipids and membrane-associated proteins in biological membranes is often detected by fluorescence microscopy. Although extremely sensitive, fluorescent labels, particularly those attached to lipid molecules, may alter their physical properties.
Date: January 20, 2004
Creator: Hutcheon, I D; Weber, P K; Marxer, C G; Park, E S & Boxer, S G
Object Type: Article
System: The UNT Digital Library
OXIDATION OF BE AT ELEVATED TEMPERATURE (open access)

OXIDATION OF BE AT ELEVATED TEMPERATURE

None
Date: September 20, 2004
Creator: Cook, R C & Gunther, J
Object Type: Report
System: The UNT Digital Library
A Tutorial on Detection and Characterization of Special Behavior in Large Electric Power Systems (open access)

A Tutorial on Detection and Characterization of Special Behavior in Large Electric Power Systems

The objective of this document is to report results in the detection and characterization of special behavior in large electric power systems. Such behavior is usually dynamic in nature, but not always. This is also true for the underlying sources of special behavior. At the device level, a source of special behavior might be an automatic control system, a dynamic load, or even a manual control system that is operated according to some sharply defined policy. Other possible sources include passive system conditions, such as the state of a switched device or the amount of power carried on some critical line. Detection and characterization are based upon “signature information” that is extracted from the behavior observed. Characterization elements include the signature information itself, the nature of the behavior and its likely causes, and the associated implications for the system or for the public at large. With sufficient data and processing, this characterization may directly identify a particular condition or device at a specific location. Such conclusive results cannot always be done from just one observation, however. Information environments that are very sparse may require multiple observations, comparative model studies, and even direct testing of the system.
Date: August 20, 2004
Creator: Hauer, John F. & DeSteese, John G.
Object Type: Report
System: The UNT Digital Library
A Model-Fitting Approach to Characterizing Polymer Decomposition Kinetics (open access)

A Model-Fitting Approach to Characterizing Polymer Decomposition Kinetics

The use of isoconversional, sometimes called model-free, kinetic analysis methods have recently gained favor in the thermal analysis community. Although these methods are very useful and instructive, the conclusion that model fitting is a poor approach is largely due to improper use of the model fitting approach, such as fitting each heating rate separately. The current paper shows the ability of model fitting to correlate reaction data over very wide time-temperature regimes, including simultaneous fitting of isothermal and constant heating rate data. Recently published data on cellulose pyrolysis by Capart et al. (TCA, 2004) with a combination of an autocatalytic primary reaction and an nth-order char pyrolysis reaction is given as one example. Fits for thermal decomposition of Estane, Viton-A, and Kel-F over very wide ranges of heating rates is also presented. The Kel-F required two parallel reactions--one describing a small, early decomposition process, and a second autocatalytic reaction describing the bulk of pyrolysis. Viton-A and Estane also required two parallel reactions for primary pyrolysis, with the first Viton-A reaction also being a minor, early process. In addition, the yield of residue from these two polymers depends on the heating rate. This is an example of a competitive reaction between …
Date: July 20, 2004
Creator: Burnham, A K & Weese, R K
Object Type: Article
System: The UNT Digital Library
Ultrasonic Examination of Double-Shell Tank 241-SY-103. Examination completed February 2004 (open access)

Ultrasonic Examination of Double-Shell Tank 241-SY-103. Examination completed February 2004

COGEMA Engineering Corporation (COGEMA), under a contract from CH2M Hill Hanford Group (CH2M Hill), has performed an ultrasonic nondestructive examination of selected portions of Double-Shell Tank 241-SY-103. The purpose of this examination was to provide information that could be used to evaluate the integrity of the wall of the primary tank. The requirements for the ultrasonic examination of Tank 241-SY-103 were to detect, characterize (identify, size, and locate), and record measurements made of any wall thinning, pitting, or cracks that might be present in the wall of the primary tank. Any measurements that exceed the requirements set forth in the Engineering Task Plan (ETP), RPP-17750 (Jensen 2003) and summarized on page 1 of this document, are reported to CH2M Hill and the Pacific Northwest National Laboratory (PNNL) for further evaluation. Under the contract with CH2M Hill, all data is to be recorded on disk and paper copies of all measurements are provided to PNNL for third-party evaluation. PNNL is responsible for preparing a report that describes the results of the COGEMA ultrasonic examinations.
Date: February 20, 2004
Creator: Pardini, Allan F. & Posakony, Gerald J.
Object Type: Report
System: The UNT Digital Library
A screening model for evaluating the degradation and transport of MTBE and other fuel oxygenates in the subsurface (open access)

A screening model for evaluating the degradation and transport of MTBE and other fuel oxygenates in the subsurface

Methyl tert-butyl ether (MTBE) has received high attention as it contributed to cleaner air and contaminated thousands of underground storage tank sites. Because MTBE is very water soluble, it is more difficult to remove from water by conventional remediation techniques. Therefore, biodegradation of MTBE has become a remediation alternative. In order to understand the transport and transformation processes, they present a closed form solution as a screening tool in this paper. The possible reaction pathways of first-order reactions are described as a reaction matrix. The singular value decomposition is conducted analytically to decouple the partial differential equations of the multi-species transport system coupled by the reaction matrix into multiple independent subsystems. Therefore, the complexity of mathematical description for the reactive transport system is significantly reduced and analytical solutions may be previously available or easily derived.
Date: April 20, 2004
Creator: Sun, Y. & Lu, X.
Object Type: Article
System: The UNT Digital Library
Hyperdispersion Grating Arrangements for Compact Pulse Compressors and Expanders (open access)

Hyperdispersion Grating Arrangements for Compact Pulse Compressors and Expanders

A novel, but general, arrangement of parallel sets of gratings is presented that can effectively increase the dispersion of pulse compressors and expanders by over an order of magnitude. These arrangements will dramatically reduce the footprint of the pulse compressors and expanders used in CPA.
Date: April 20, 2004
Creator: Fittinghoff, D N; Molander, W A & Barty, C J
Object Type: Article
System: The UNT Digital Library
BioAerosol Mass Spectrometry: Reagentless Detection of Individual Airborne Spores and Other Bioagent Particles Based on Laser Desorption/Ionization Mass Spectrometry (open access)

BioAerosol Mass Spectrometry: Reagentless Detection of Individual Airborne Spores and Other Bioagent Particles Based on Laser Desorption/Ionization Mass Spectrometry

Better devices are needed for the detection of aerosolized biological warfare agents. Advances in the ongoing development of one such device, the BioAerosol Mass Spectrometry (BAMS) system, are described here in detail. The system samples individual, micrometer-sized particles directly from the air and analyzes them in real-time without sample preparation or use of reagents. At the core of the BAMS system is a dual-polarity, single-particle mass spectrometer with a laser based desorption and ionization (DI) system. The mass spectra produced by early proof-of-concept instruments were highly variable and contained limited information to differentiate certain types of similar biological particles. The investigation of this variability and subsequent changes to the DI laser system are described. The modifications have reduced the observed variability and thereby increased the usable information content in the spectra. These improvements would have little value without software to analyze and identify the mass spectra. Important improvements have been made to the algorithms that initially processed and analyzed the data. Single particles can be identified with an impressive level of accuracy, but to obtain significant reductions in the overall false alarm rate of the BAMS instrument, alarm decisions must be made dynamically on the basis of multiple analyzed particles. …
Date: July 20, 2004
Creator: Steele, P T
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Actinide Cross Section Evaluations (open access)

Actinide Cross Section Evaluations

The Livermore Computational Nuclear Physics group is charged with producing updated neutron incident cross section evaluations for all the actinides in the coming year, concentrating on neutron induced fission, neutron capture and (n,2n) cross sections. We attack this daunting task either by adopting other recent evaluations or by performing our own. Owing to the large number of nuclei involved, we seek to automate this process as much as possible. For this purpose, we have developed a series of computer codes: x41, an interface to the EXFOR database, fete, a code that translates ENDF/B formatted evaluations into a computationally convenient form, and da{_}fit, a fitting code that takes all relevant EXFOR data for a reaction or set of reactions and performs a generalized least square fit to them, subject to various constraints and other prior information.
Date: September 20, 2004
Creator: Brown, D. A.; Loyola, B. & McNabb, D.
Object Type: Article
System: The UNT Digital Library
The Physics of Fusion Energy: Why We (Probably) Can't Make a Reactor on the Head of a Pin (open access)

The Physics of Fusion Energy: Why We (Probably) Can't Make a Reactor on the Head of a Pin

None
Date: May 20, 2004
Creator: Perkins, L J
Object Type: Article
System: The UNT Digital Library

Nondestructive Evaluation of Multilayered Structures using Horizontal Shear Modes Generated by an Electromagnetic Acoustic Array Transducer

None
Date: May 20, 2004
Creator: Quarry, Michael J.
Object Type: Presentation
System: The UNT Digital Library
Protein adducts of the prostate carcinogen PhIP in children (open access)

Protein adducts of the prostate carcinogen PhIP in children

Prostate cancer is the second leading cause of cancer death in men in the United States. few epidemiology studies have indicated that exposure to PhIP, a rodent prostate carcinogen formed in meat during cooking, may be an important risk factor for prostate cancer in humans. Therefore, a highly sensitive biomarker assay is urgently needed to clarify the role of PhIP in prostate cancer. The goal of this project is to develop an assay that can be used to more accurately quantify human exposure to PhIP and potential prostate cancer risk. Our hypothesis is that an Accelerator Mass Spectrometry-based method can be developed to measure protein adducts of PhIP in the blood of humans. This will provide a measure of the internal dose, as well as the capacity for carcinogen bioactivation to a form that can initiate the cancer process. Towards this goal, we have characterized an adduct formed by PhIP in vitro with the amino acid cysteine. This adduct should provide a biomarker of dietary PhIP exposure and potential prostate cancer risk that could be used to identify individuals for prevention and for monitoring the effect chemoprevention strategies.
Date: February 20, 2004
Creator: Lawrence Livermore National Laboratory
Object Type: Report
System: The UNT Digital Library
How Accurately can we Calculate Thermal Systems? (open access)

How Accurately can we Calculate Thermal Systems?

I would like to determine how accurately a variety of neutron transport code packages (code and cross section libraries) can calculate simple integral parameters, such as K{sub eff}, for systems that are sensitive to thermal neutron scattering. Since we will only consider theoretical systems, we cannot really determine absolute accuracy compared to any real system. Therefore rather than accuracy, it would be more precise to say that I would like to determine the spread in answers that we obtain from a variety of code packages. This spread should serve as an excellent indicator of how accurately we can really model and calculate such systems today. Hopefully, eventually this will lead to improvements in both our codes and the thermal scattering models that they use in the future. In order to accomplish this I propose a number of extremely simple systems that involve thermal neutron scattering that can be easily modeled and calculated by a variety of neutron transport codes. These are theoretical systems designed to emphasize the effects of thermal scattering, since that is what we are interested in studying. I have attempted to keep these systems very simple, and yet at the same time they include most, if not …
Date: April 20, 2004
Creator: Cullen, D.; Blomquist, R. N.; Dean, C.; Heinrichs, D.; Kalugin, M. A.; Lee, M. et al.
Object Type: Report
System: The UNT Digital Library
Simulations of Underground Structures Subjected to Dynamic Loading Using the Distinct Element Method (open access)

Simulations of Underground Structures Subjected to Dynamic Loading Using the Distinct Element Method

We present results from an investigation into the stability of underground structures in response to explosive loading. Field tests indicate that structural response can be dominated by the effect of preexisting fractures and faults in the rock mass. Consequently, accurate models of underground structures must take into account plastic deformations across fractures and not simply within the intact portions of the rock mass. The distinct element method (DEM) is naturally suited to simulating such systems because it can explicitly accommodate the blocky nature of natural rock masses. We will discuss details specific to our implementation of the DEM and summarize recent results.
Date: August 20, 2004
Creator: Morris, J P; Bonner, M P & Heuze, F E
Object Type: Article
System: The UNT Digital Library