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2,852 Matching Results
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Novel Source Ionizer Options for Polarized Ions
N/A
Date:
September 1, 2000
Creator:
A., Hershcovitch
Object Type:
Report
System:
The UNT Digital Library
Polarized proton beam acceleration with a single Siberian Snake in each RHIC ring
N/A
Date:
March 1, 2000
Creator:
A., Lehrach; Luccio, A. U. & Roser, T.
Object Type:
Report
System:
The UNT Digital Library
CATALYSIS SCIENCE AND TECHNOLOGY
This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Our objectives were to develop a multidisciplinary team and capabilities to develop a fundamental understanding of homogeneous, heterogeneous, and heterogenized catalysts. With the aid of theoretical chemistry approaches we explored and characterized the chemical reactivity and physical properties of a large number of catalytic systems.
Date:
August 1, 2000
Creator:
ABRAMS, M.; BAKER, R. & AL, ET
Object Type:
Report
System:
The UNT Digital Library
EFFECTS OF XE ION IRRADIATION AND SUBSEQUENT ANNEALING ON THE PROPERTIES OF MAGNESIUM-ALUMINATE SPINEL
Single crystals of magnesium-aluminate spinel MgAl{sub 2}O{sub 4} were irradiated with 340 keV Xe{sup 2} ions at {minus}173 C ({approximately} 100 K). A fluence of 1 x 10{sup 20} Xe/m{sup 2} created an amorphous layer at the surface of the samples. The samples were annealed for 1 h at different temperatures ranging from 130 C to 880 C. Recrystallization took place in the temperature interval between 610 C and 855 C. Transmission electron microscopy (TEM) images show two distinct layers near the surface: (1) a polycrystalline layer with columnar grain structure; and (2) a buried damaged layer epitaxial with the substrate. After annealing at 1100 C for 52 days, the profile of implanted Xe ions did not change, which means that Xe ions are not mobile in the spinel structure up to 1100 C. The thickness of the buried damaged layer decreased significantly in the 1100 C annealed sample comparing to the sample annealed for 1 h at 855 C.
Date:
April 1, 2000
Creator:
AFANASYEV, I. & AL, ET
Object Type:
Article
System:
The UNT Digital Library
Spectroscopic Detection of Pathogens
The goal of this LDRD Research project was to provide a preliminary examination of the use of infrared spectroscopy as a tool to detect the changes in cell cultures upon activation by an infectious agent. Due to a late arrival of funding, only 5 months were available to transfer and setup equipment at UTTM,develop cell culture lines, test methods of in-situ activation and collect kinetic data from activated cells. Using attenuated total reflectance (ATR) as a sampling method, live cell cultures were examined prior to and after activation. Spectroscopic data were collected from cells immediately after activation in situ and, in many cases for five successive hours. Additional data were collected from cells activated within a test tube (pre-activated), in both transmission mode as well as in ATR mode. Changes in the infrared data were apparent in the transmission data collected from the pre-activated cells as well in some of the pre-activated ATR data. Changes in the in-situ activated spectral data were only occasionally present due to (1) the limited time cells were studied and (2) incomplete activation. Comparison of preliminary data to infrared bands reported in the literature suggests the primary changes seen are due an increase in ribonucleic …
Date:
November 1, 2000
Creator:
ALAM,M. KATHLEEN; TIMLIN,JERILYN A.; MARTIN,LAURA E.; HJELLE,DRIAN; LYONS,RICK & GARRISON,KRISTIN
Object Type:
Report
System:
The UNT Digital Library
Molecular dynamic simulations, {sup 6}Li solid state NMR and ultraphosphate glasses
The author's laboratory continues to use NMR to investigate the structure and dynamics in amorphous materials, including the local structure of ultraphosphate glasses. Changes in the alkali environment in these phosphate glasses as a function of modifier concentration has recently been probed using {sup 6}Li and {sup 23}Na solid state NMR. Molecular dynamic (MD) simulations have also been performed in an attempt to gain additional insight into the variations of the local structure. Interestingly, although there are distinct variations in the Li coordination number as well as the Li-O bond lengths in the MD simulations (with a minimum or maximum in these parameters near the 20% Li{sub 2}O concentration), a linear change in the {sup 6}Li NMR chemical shift is observed between 5 and 50% Li{sub 2}O mole fraction. One would expect that such variations should be observable in the NMR chemical shift. In an attempt to understand this behavior the author has performed empirical calculation of the {sup 6}Li NMR chemical shift directly from the structures obtained in the MD simulations. It has been argued that the NMR chemical shift of alkali species can be related to a chemical shift parameter A, where A is defined as the summation …
Date:
May 1, 2000
Creator:
ALAM,TODD M.
Object Type:
Article
System:
The UNT Digital Library
Monte Carlo simulations of phosphate polyhedron connectivity in glasses
Monte Carlo simulations of phosphate tetrahedron connectivity distributions in alkali and alkaline earth phosphate glasses are reported. By utilizing a discrete bond model, the distribution of next-nearest neighbor connectivities between phosphate polyhedron for random, alternating and clustering bonding scenarios was evaluated as a function of the relative bond energy difference. The simulated distributions are compared to experimentally observed connectivities reported for solid-state two-dimensional exchange and double-quantum NMR experiments of phosphate glasses. These Monte Carlo simulations demonstrate that the polyhedron connectivity is best described by a random distribution in lithium phosphate and calcium phosphate glasses.
Date:
January 1, 2000
Creator:
ALAM,TODD M.
Object Type:
Report
System:
The UNT Digital Library
MICROHOLE TECHNOLOGY PROGRESS ON BOREHOLE INSTRUMENTATION DEVELOPMENT
Microhole technology development is based on the premise that with advances in electronics and sensors, large conventional-diameter wells are no longer necessary for obtaining subsurface information. Furthermore, microholes offer an environment for improved substance measurement. The combination of deep microholes having diameters of 1-3/8 in. at their terminal depth and 7/8-in. diameter logging tools will comprise a very low cost alternative to currently available technology for deep subsurface characterization and monitoring.
Date:
September 1, 2000
Creator:
ALBRIGHT, J.
Object Type:
Article
System:
The UNT Digital Library
Fast Grid Search Algorithm for Seismic Source Location
The spatial and temporal origin of a seismic energy source are estimated with a first grid search technique. This approach has greater likelihood of finding the global rninirnum of the arrival time misiit function compared with conventional linearized iterative methods. Assumption of a homogeneous and isotropic seismic velocity model allows for extremely rapid computation of predicted arrival times, but probably limits application of the method to certain geologic environments and/or recording geometries. Contour plots of the arrival time misfit function in the vicinity of the global minimum are extremely useful for (i) quantizing the uncertainty of an estimated hypocenter solution and (ii) analyzing the resolving power of a given recording configuration. In particular, simultaneous inversion of both P-wave and S-wave arrival times appears to yield a superior solution in the sense of being more precisely localized in space and time. Future research with this algorithm may involve (i) investigating the utility of nonuniform residual weighting schemes, (ii) incorporating linear and/or layered velocity models into the calculation of predicted arrival times, and (iii) applying it toward rational design of microseismic monitoring networks.
Date:
July 1, 2000
Creator:
ALDRIDGE,DAVID F.
Object Type:
Report
System:
The UNT Digital Library
SPALL STUDIES IN COPPER FOILS USING THE LASER-DRIVEN MINIFLYER
None
Date:
September 1, 2000
Creator:
ALEXANDER, D. J.; ROBBINS, D. L. & SHEFFIELD, S. A.
Object Type:
Article
System:
The UNT Digital Library
INVESTIGATION OF HALO FORMATION IN CONTINUOUS BEAMS USING WEIGHTED POLYNOMIAL EXPANSIONS AND PERTURBATIONAL ANALYSIS
We consider halo formation in continuous beams oscillating at natural modes by inspecting particle trajectories. Trajectory equations containing field nonlinearities are derived from a weighted polynomial expansion. We then use perturbational techniques to further analyze particle motion.
Date:
August 1, 2000
Creator:
ALLEN, C.
Object Type:
Article
System:
The UNT Digital Library
Cooperative Monitoring Center Occasional Paper/16: The Potential of Technology for the Control of Small Weapons: Applications in Developing Countries
For improving the control of small arms, technology provides many possibilities. Present and future technical means are described in several areas. With the help of sensors deployed on the ground or on board aircraft, larger areas can be monitored. Using tags, seals, and locks, important objects and installations can be safeguarded better. With modern data processing and communication systems, more information can be available, and it can be more speedily processed. Together with navigation and transport equipment, action can be taken faster and at greater range. Particular considerations are presented for cargo control at roads, seaports, and airports, for monitoring designated lines, and for the control of legal arms. By starting at a modest level, costs can be kept low, which would aid developing countries. From the menu of technologies available, systems need to be designed for the intended application and with an understanding of the local conditions. It is recommended that states start with short-term steps, such as acquiring more and better radio transceivers, vehicles, small aircraft, and personal computers. For the medium term, states should begin with experiments and field testing of technologies such as tags, sensors, and digital communication equipment.
Date:
July 1, 2000
Creator:
ALTMANN, JURGEN
Object Type:
Report
System:
The UNT Digital Library
Methodology for characterizing modeling and discretization uncertainties in computational simulation
This research effort focuses on methodology for quantifying the effects of model uncertainty and discretization error on computational modeling and simulation. The work is directed towards developing methodologies which treat model form assumptions within an overall framework for uncertainty quantification, for the purpose of developing estimates of total prediction uncertainty. The present effort consists of work in three areas: framework development for sources of uncertainty and error in the modeling and simulation process which impact model structure; model uncertainty assessment and propagation through Bayesian inference methods; and discretization error estimation within the context of non-deterministic analysis.
Date:
March 1, 2000
Creator:
ALVIN,KENNETH F.; OBERKAMPF,WILLIAM L.; RUTHERFORD,BRIAN M. & DIEGERT,KATHLEEN V.
Object Type:
Report
System:
The UNT Digital Library
Interim Measures to Limit the Migration of Radioactive Contaminants through the Vadose Zone at Hanford Single Shell Tank (SST) Farms
None
Date:
December 1, 2000
Creator:
ANDERSON, F.J.
Object Type:
Article
System:
The UNT Digital Library
Status of the DOE/Sandia Blade Manufacturing Program
None
Date:
November 1, 2000
Creator:
ASHWILL,THOMAS D.
Object Type:
Article
System:
The UNT Digital Library
DISPERSION ANALYSIS OF RADIATION/THERMAL FRONTS WITH FULL RESOLVED SPECTRAL OPACITY VARIATION.
The radiation transport and linearized thermal energy equations have been analyzed to find the temporal dependence of the component modes in a radiation/thermal front. The fully resolved spectral variation of the opacity as a function of energy, as well as the exact time and angular dependence, is treated in this work. As we are able to study arbitrarily complicated opacity spectra, we stress the importance of the new results as a check on the effect of using opacity averages.
Date:
December 1, 2000
Creator:
AUER, L. & LOWRIE, R.
Object Type:
Article
System:
The UNT Digital Library
COSMIC-RAY PRODUCTION OF 6,7Li BY THE ALPHA + ALPHA REACTION
None
Date:
September 1, 2000
Creator:
AUSTIN, S. M. & MERCER, D. J.
Object Type:
Article
System:
The UNT Digital Library
EXACT SOLUTION OF HEAT CONDUCTION IN A TWO-DOMAIN COMPOSITE CYLINDER WITH AN ORTHOTROPIC OUTER LAYER.
The transient exact solution of heat conduction in a two-domain composite cylinder is developed using the separation of variables technique. The inner cylinder is isotropic and the outer cylindrical layer is orthotropic. Temperature solutions are obtained for boundary conditions of the first and second kinds at the outer surface of the orthotropic layer. These solutions are applied to heat flow calorimeters modeling assuming that there is heat generation due to nuclear reactions in the inner cylinder. Heat flow calorimeter simulations are carried out assuming that the inner cylinder is filled with plutonium oxide powder. The first objective in these simulations is to predict the onset of thermal equilibrium of the calorimeter with its environment. Two types of boundary conditions at the outer surface of the orthotropic layer are used to predict thermal equilibrium. The procedure developed to carry out these simulations can be used as a guideline for the design of calorimeters. Another important application of these solutions is on the estimation of thermophysical properties of orthotropic cylinders. The thermal conductivities in the vertical, radial and circumferential directions of the orthotropic outer layer can be estimated using this exact solution and experimental data. Simultaneous estimation of the volumetric heat capacity …
Date:
November 1, 2000
Creator:
AVILES-RAMOS, C. & RUDY, C.
Object Type:
Article
System:
The UNT Digital Library
Combined approach to the inverse protein folding problem. Final report
The main scientific contribution of the project ''Combined approach to the inverse protein folding problem'' submitted in 1996 and funded by the Department of Energy in 1997 is the formulation and development of the idea of the multilink recognition method for identification of functional and structural homologues of newly discovered genes. This idea became very popular after they first announced it and used it in prediction of the threading targets for the CASP2 competition (Critical Assessment of Structure Prediction).
Date:
June 1, 2000
Creator:
Abagyan, Ruben A.
Object Type:
Report
System:
The UNT Digital Library
Integrating automatic differentiation with object-oriented toolkits for high-performance scientific computing.
Often the most robust and efficient algorithms for the solution of large-scale problems involving nonlinear PDEs and optimization require the computation of derivative quantities. We examine the use of automatic differentiation (AD) to provide code for computing first and second derivatives in conjunction with two parallel numerical toolkits, the Portable, Extensible Toolkit for Scientific Computing (PETSc) and the Toolkit for Advanced Optimization (TAO). We discuss how the use of mathematical abstractions for vectors and matrices in these libraries facilitates the use of AD to automatically generate derivative codes and present performance data demonstrating the suitability of this approach.
Date:
November 1, 2000
Creator:
Abate, J.; Benson, S.; Grignon, L.; Hovland, P.; McInnes, L. & Norris, B.
Object Type:
Article
System:
The UNT Digital Library
ADVANCED SORBENT DEVELOPMENT
The overall objective of this program was to develop regenerable sorbents for use in the temperature range of 343 to 538 C (650 to 1000 F) to remove hydrogen sulfide (H{sub 2}S) from coal-derived fuel gases in a fluidized-bed reactor. The goal was to develop sorbents that are capable of reducing the H{sub 2}S level in the fuel gas to less than 20 ppmv in the specified temperature range and pressures in the range of 1 to 20 atmospheres, with chemical characteristics that permit cyclic regeneration over many cycles without a drastic loss of activity, as well as physical, characteristics that are compatible with the fluidized bed application. This topical report focuses on the investigation directed toward preparation of zinc-based sorbents using the sol-gel approach that has been shown to require only a moderate temperature for calcination, while resulting in significantly more attrition-resistant sorbents. The sorbents prepared in this part of the investigation and the results from their evaluation in packed-bed and fluidized-bed reactors are described in this report.
Date:
January 1, 2000
Creator:
Abbasian, Javad
Object Type:
Report
System:
The UNT Digital Library
CONTINUED DEVELOPMENT OF THE ROTARY COMBUSTOR FOR REFIRING PULVERIZED COAL BOILERS
The Rotary Combustor is a novel concept for burning coal with low SO{sub 2} and NO{sub x} emissions. It burns crushed coal in a fluid bed where the bed is maintained in a rotating drum by centripetal force. Since this force may be varied, the combustor may be very compact, and thus be a direct replacement for a p.c. burner on existing boilers. The primary objective of this project is to demonstrate that a typical industrial boiler can be refired with the modified prototype Rotary Combustor to burn Ohio high-sulfur coal with low emissions of SO{sub 2} and NO{sub x}. The primary problem that must be resolved to demonstrate sustained operations with coal is temperature control in the rotating fluid bed. The prototype Rotary Combustor was assembled and installed on the T-850P CNB boiler at the CONSOL Energy site in South Park, Pennsylvania. Several design improvements were investigated and implemented during the assembly to improve the prototype Rotary Combustor operations compared to prior tests at Detroit Stoker in Monroe, Michigan. An Operating Manual and Safety Review were completed. The shakedown test phase was initiated. Two major problems were initially encountered: binding of the rotating drum at operating temperatures, and reduced …
Date:
November 1, 2000
Creator:
Abbott, Murray F.; Mereb, Jamal B.; Hanson, Simon P. & Virr, Michael J.
Object Type:
Report
System:
The UNT Digital Library
NEW PARADIGM IN SEPARATIONS: MOLECULAR RECOGNITION MEMBRANES
None
Date:
October 1, 2000
Creator:
Abney, K.D. & Barr, M.E.
Object Type:
Article
System:
The UNT Digital Library
The Migration and Entrapment of DNAPLs in Physically and Chemically Heterogeneous Porous Media
This document summarizes EMSP funded research designed to improve our understanding of and ability to simulate the influence of subsurface chemical heterogeneities on DNAPL flow and entrapment in the saturated zone. Specific project objectives include: (i) the quantification of DNAPL interfacial and hydraulic properties; (ii) development and assessment of constitutive hydraulic property and continuum based multiphase flow models; (iii) exploration of DNAPL migration and entrapment in heterogeneous systems at larger scales; and (iv) development of innovative remediation schemes.
Date:
June 1, 2000
Creator:
Abriola, Linda M. & Demond, Avery H.
Object Type:
Report
System:
The UNT Digital Library