Access
Partner
UNT Libraries Government Documents Department
11,815
Oklahoma Historical Society
1,798
UNT Libraries Special Collections
1,329
UNT Libraries
528
Sterling Municipal Library
321
Carl Albert Congressional Research and Studies Center
196
Abilene Christian University Library
182
Comanche Public Library
159
Alvin Community College
154
Rice University Woodson Research Center
132
136 More
Collection
Office of Scientific & Technical Information Technical Reports
10,244
Texas Digital Newspaper Program
3,654
Oklahoma Digital Newspaper Program
2,068
Tocker Foundation Grant
1,716
Congressional Research Service Reports
736
KXAS-NBC 5 News Collection
658
Chickasha Newspaper Collection
544
Texas State Publications
395
Abilene Library Consortium
333
Altus Times-Democrat
312
271 More
Serial/Series Title
The Altus Times
312
The Baytown Sun
312
Sapulpa Daily Herald
310
The Chickasha Daily Express
266
The Perry Daily Journal
255
The Daily Chickasha Star
220
The Oklahoma Daily
196
NBC News Clips
166
The North Texas Daily
131
The Real War: Flesh vs. Spirit, Studies in Galatians. 80th Annual Lectureship
108
557 More
Degree Department
Department of Psychology
41
Department of Biological Sciences
27
Chemistry
20
Department of Counseling, Development and Higher Education
20
College of Music
17
Department of Technology and Cognition
15
School of Visual Arts
15
Department of Teacher Education and Administration
12
Department of English
10
Department of Physics
9
55 More
Degree Discipline
Degree Level
Country
States
Year
Month
Language
19,998 Matching Results
Results open in a new window/tab.
A Compton camera for spectroscopic imaging from 100 keV to 1 MeV
A review of spectroscopic imaging issues, applications, and technology is presented. Compton cameras based on solid state semiconductor detectors stands out as the best system for the nondestructive assay of special nuclear materials. A camera for this application has been designed based on an efficient specific purpose Monte Carlo code developed for this project. Preliminary experiments have been performed which demonstrate the validity of the Compton camera concept and the accuracy of the code. Based on these results, a portable prototype system is in development. Proposed future work is addressed.
Date:
December 31, 1998
Creator:
Earnhart, J. R. D.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Computational modeling of materials processing and processes
This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Anisotropic mechanical properties of densified BSCCO powders are of paramount importance during thermo-mechanical processing of superconducting tapes and wires. Maximum current transport requires high relative density and a high degree of alignment of the single crystal planes of the BSCCO. Unfortunately this configuration causes high stresses that can lead to cracking, and thus reduce the density, and the conductive properties of the tape. The current work develops a micromechanical material mode to model is calibrated and compared to experimental results, and then employed to analyze the effects of initial texture and confinement pressure and shear strains in the core of oxide powder-in-tube (OPIT) processed tapes are calculated by finite-element analysis. The calculated deformations were then applied as boundary conditions to the micromechanical model. Our calculated results were used to interpret a set of prototypical rolling experiments. 11 refs., 5 figs.
Date:
December 31, 1998
Creator:
Asaro, R. J.; Schoenfeld, S. E.; Ahzi, S.; Zhu, Yuntian; Bingert, J. F.; Willis, J. O. et al.
Object Type:
Report
System:
The UNT Digital Library
Computational simulations and experimental validation of a furnace brazing process
Modeling of a furnace brazing process is described. The computational tools predict the thermal response of loaded hardware in a hydrogen brazing furnace to programmed furnace profiles. Experiments were conducted to validate the model and resolve computational uncertainties. Critical boundary conditions that affect materials and processing response to the furnace environment were determined. {open_quotes}Global{close_quotes} and local issues (i.e., at the furnace/hardware and joint levels, respectively) are discussed. The ability to accurately simulate and control furnace conditions is examined.
Date:
December 31, 1998
Creator:
Hosking, F. M.; Gianoulakis, S. E. & Malizia, L. A.
Object Type:
Article
System:
The UNT Digital Library
Computerized materials protection, control, and accountability at the Institute of Physics and Power Engineering
As part of a multifaceted approach to protecting its nuclear materials, The Institute of Physics and Power Engineering (IPPE) at Obninsk, Russia, has been computerizing its materials protection, control, and accountability capabilities. This is being accomplished in collaboration with the CoreMAS team at Los Alamos National Laboratory. Such international cooperation in applying advanced science and technology to managing and controlling nuclear materials will help reduce the threat of nuclear weapons proliferation by preventing acquisition of weapons-grade nuclear materials by unauthorized individuals, organizations, or states. One important characteristic of IPPE is that it encompasses several facilities that manage nuclear materials, and three of these facilities already operate their own independent (or independently developed) computerized accounting systems. This paper focuses on the importance of compatibility between the computerized accountability systems at the facilities, the ability of the individual systems to communicate with a single site-wide system, and the necessity of coordination between facilities in designing and developing computerized systems. The authors believe that the lessons learned at IPPE in coordinating these efforts have wide-ranging significance for other sites with multiple facilities.
Date:
December 31, 1998
Creator:
Efimenko, V.; Goryunov, V. & Ilyantsev, A.
Object Type:
Article
System:
The UNT Digital Library
Configurational diffusion of asphaltenes in fresh and aged catalyst extrudates. Final technical report, September 20, 1991--September 30, 1996
The overall objective of this project was to investigate the diffusion of coal and petroleum asphaltenes in the pores of a supported catalyst. Experimental measurements together with mathematical modeling was conducted to determine how the diffusion rate of asphaltenes, as well as some model compounds, depended on molecule sizes and shapes. The process of diffusion in the pores of a porous medium may occur by several mechanisms. Hindered diffusion occurs when the sizes of the diffusion molecules are comparable to those of the porous pores through which they are diffusing. Hindered diffusion phenomena have been widely observed in catalytic hydrotreatment of asphaltenes, heavy oils, coal derived liquids, etc. Pore diffusion limitations can be greater in spent catalysts due to the deposition of coke and metals in the pores. In this work, a general mathematical model was developed for the hindered diffusion-adsorption of solute in a solvent onto porous materials, e. g. catalysts, from a surrounding bath. This diffusion model incorporated the nonuniformities of pore structures in the porous media. A numerical method called the Method of Lines was used to solve the nonlinear partial differential equations resulting from the mathematical model. The accuracy of the numerical solution was verified by …
Date:
December 31, 1998
Creator:
Guin, J.A.
Object Type:
Report
System:
The UNT Digital Library
Constitutive modeling of weak and strong shock-initiation of porous explosives
A continuum based reactive burn model for shocked loaded high explosives has been developed that uses heterogeneous distribution of pore collapse energy to one or more of the constituents (a hot spot) as an ignition source, represents constituents with independent equations of state and has multiple competing and sequential chemical reactions. Reaction propagates from the hot spot to the remainder of the material through either a pressure or temperature dependence of heat transfer through a film layer. The reaction may be quenched by heat transfer or shock release if it is not rapid enough.
Date:
December 31, 1998
Creator:
Bennett, L.S.
Object Type:
Article
System:
The UNT Digital Library
Contamination control aspects of attaching waste drums to the WIPP Waste Characterization Chamber
Argonne National Laboratory West (ANL-W) is verifying the characterization and repackaging of contact-handled transuranic (CH-TRU) mixed waste in support of the Waste Isolation Pilot Program (WIPP) project located in Carlsbad, New Mexico. The WIPP Waste Characterization Chamber (WCC) was designed to allow opening of transuranic waste drums for this process. The WCC became operational in March of 1994 and has characterized approximately 240 drums of transuranic waste. The waste drums are internally contaminated with high levels of transuranic radionuclides. Attaching and detaching drums to the glove box posed serious contamination control problems. Prior to characterizing waste, several drum attachment techniques and materials were evaluated. An inexpensive HEPA filter molded into the bagging material helps with venting during detachment. The current techniques and procedures used to attach and detach transuranic waste drums to the WCC are described.
Date:
December 31, 1998
Creator:
Rubick, L. M. & Burke, L. L.
Object Type:
Article
System:
The UNT Digital Library
Continued development of an atmospheric monitoring mass spectrometry system - task 2.2. Topical report, January 1, 1995--December 31, 1995
The objective of this project was the development of a mass spectrometric methodology applicable to the field determination of Volatile Organic Compounds (VOC`s), such as BTEX components (Benzene, Toluene, Ethylbenzene, and Xylenes). A combination of chemical ionization, selective ion storage, and tandem mass spectrometry was planned to be employed with an ion trap mass spectrometry system. The Gas Chromatography Mass Spectrometry (GC-MS) interface on the ion trap system was modified to permit direct atmospheric monitoring. Through the use of tandem mass spectrometry methods the need for chromatographic separation would be eliminated reducing the overall size and complexity of the system.
Date:
December 31, 1998
Creator:
King, F. L.
Object Type:
Report
System:
The UNT Digital Library
Continued fractions: Yet another tool to overcome the curse of dimensionality
The authors provide a rapid prediction method, in which a larger number of antecedents than currently considered is accounted for. To this end, they encode the successive (possibly rescaled) values of a time series, as the partial quotients of a continued fraction, resulting in a number from the unit interval. The accuracy of a ruled-based system utilizing this coding is investigated to some extent. Qualitative criteria for the applicability of the algorithm are formulated.
Date:
December 31, 1998
Creator:
Zardecki, A.
Object Type:
Article
System:
The UNT Digital Library
Control of the accumulation of non-process elements and organic compounds in pulp mills with bleach filtrate reuse. Milestones and progress, Quarter 9 (July 1--September 30, 1998)
The two approach changes that were discussed and recommended in the Quarter 8 (April 1--June 30, 1998) progress report have been implemented in the current project plan. The OLI software has been used to develop a preliminary process model for predicting the distribution of NPE`s in a two stage brownstock washer, and the OLI database has been upgraded to include improved chemical equilibrium data for metal-organic interactions. This exercise served as a tool to evaluate the data and methods developed in this study, and to demonstrate its utility to industry. The Weyerhaeuser-NAELS software has also been applied to predicting inorganic solubility behavior. Task C-1.2, Estimation of unavailable thermodynamic parameters (scheduled completion date: 12/97), has been combined with Task D-2.1, Evaluation of the estimation procedure (scheduled completion date: 3/99) with a new scheduled completion date of 8/99. A model for the adsorption of metal ions on wood pulp fibers will include transport effects as well as adsorption equilibrium, and will be combined with a brownstock washer model to evaluate its predictive capability in comparison with mill data, and to demonstrate the applicability of the results obtained in this project. Three tasks are behind schedule: Task A-2.3, Measurement of stability constants for …
Date:
December 31, 1998
Creator:
Frederick, W. J.; Laver, M. L.; Rorrer, G. L.; Rudie, A. W. & Schmidl, W.
Object Type:
Report
System:
The UNT Digital Library
Coolside Waste Management Research. Final report, April 23, 1991--June 30, 1996
This study was initiated during a successful test of the Coolside flue gas desulfurization technology at Ohio Edison`s Edgewater generating station in 1991. Coolside is a lime duct technology which is installed on the downstream side of the last heat exchanger. As tested by Ohio Edison, it also employs an alkali reagent, in this case NaOH, to enhance sulfur capture. The overall goal of this study was to develop sufficient chemical and physical data to insure the environmentally safe disposal of the material. This final report summarizes the important aspects of the project, but it does not present all of the data that was produced. Further details may be found in the monthly and quarterly reports that were filed with the Morgantown Energy Technology Center. This report is organized into six chapters which present the important conclusions of the principal areas of investigation.
Date:
December 31, 1998
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Cooper Review (Cooper, Tex.), Vol. 118, No. 52, Ed. 1 Thursday, December 31, 1998
Weekly newspaper from Cooper, Texas that includes local, state, and national news along with advertising.
Date:
December 31, 1998
Creator:
Kisic, Theresa
Object Type:
Newspaper
System:
The Portal to Texas History
Corrections for the emission probabilities of the intense gamma rays from {sup 238}U and applying them to uranium isotopic analysis
Gamma-ray emission probabilities of {sup 235}U and {sup 238}U have been studied extensively. While the gamma-ray emission probabilities for {sup 235}U and are well known, the emission probabilities for {sup 238}U differ widely from one study to another. This study indicates that one of the causes of the large discrepancies in the studies may be due to the true coincidence summing of many gamma rays from the decay of {sup 238}U daughters. The intensities of some of the intense gamma rays of {sup 238}U compared with the others were reduced by as much as 16% when the 21-mm-thick U{sub 3}O{sub 8} samples were moved from 15 cm to putting them in contact with the detector. With better knowledge of the gamma-ray emission probabilities and understanding the summing effects of specific gamma rays, the isotopic concentration of uranium can be better analyzed. The results of the isotopic analysis using fixed energy response function analysis with multiple efficiencies (FRAM) with the summing correction are presented in this paper.
Date:
December 31, 1998
Creator:
Vo, D. T.; Sampson, T. E. & Staples, P.
Object Type:
Article
System:
The UNT Digital Library
Coupling experimental data and a prototype model to probe the physical and chemical processes of 2,4-dinitroimidazole solid-phase thermal decomposition
The time-dependent, solid-phase thermal decomposition behavior of 2,4-dinitroimidazole (2,4-DNI) has been measured utilizing simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) methods. The decomposition products consist of gaseous and non-volatile polymeric products. The temporal behavior of the gas formation rates of the identified products indicate that the overall thermal decomposition process is complex. In isothermal experiments with 2,4-DNI in the solid phase, four distinguishing features are observed: (1) elevated rates of gas formation are observed during the early stages of the decomposition, which appear to be correlated to the presence of exogenous water in the sample; (2) this is followed by a period of relatively constant rates of gas formation; (3) next, the rates of gas formation accelerate, characteristic of an autocatalytic reaction; (4) finally, the 2,4-DNI is depleted and gaseous decomposition products continue to evolve at a decreasing rate. A physicochemical and mathematical model of the decomposition of 2,4-DNI has been developed and applied to the experimental results. The first generation of this model is described in this paper. Differences between the first generation of the model and the experimental data collected under different conditions suggest refinements for the next generation of the model.
Date:
December 31, 1998
Creator:
Behrens, R.; Minier, L. & Bulusu, S.
Object Type:
Report
System:
The UNT Digital Library
Cratering behavior in single- and poly-crystalline copper irradiated by an intense pulsed ion beam
When treated with intense pulsed ion beams (IPIB), many materials exhibit increased wear resistance, fatigue life, and hardness. However, this treatment often results in cratering and roughening of the surface. In this work, high purity single crystal and polycrystalline copper samples were irradiated with pulses from an IPIB to gain insight into the causes of this cratering behavior. Samples were treated with 1,2,5, and 10 shots at 2 J/cm{sup 2} and 5 J/cm{sup 2} average energy fluence per shot. Shots were about 400 ns in duration and consisted of a mixture of carbon, hydrogen, and oxygen ions at 300 keV. It was found that the single crystal copper cratered far less than the polycrystalline copper at the lower energy fluence. At the higher energy fluence, cratering was replaced by other forms of surface damage, and the single crystal copper sustained less damage at all but the largest number of shots. Molten debris from the Lucite anode (the ion source) was removed and redeposited on the samples with each shot.
Date:
December 31, 1998
Creator:
Wood, B. P.; Bitteker, L. J.; Waganaar, W. J. & Perry, A. J.
Object Type:
Report
System:
The UNT Digital Library
Creative PDB`s (parts databases)
PDB component property entries and creative picklists can make the schematic entry process and downstream tools such as BOM generation more useful. This presentation will show how creative PDB`s can enhance the design process. Examples of PDB entries developed at Los Alamos National Laboratory will be discussed.
Date:
December 31, 1998
Creator:
Cote, T.J.
Object Type:
Article
System:
The UNT Digital Library
Creep and creep-rupture behavior of a continuous strand, swirl mat reinforced polymer composite in automotive environments
Creep and creep-rupture behavior of an isocyanurate based polyurethane matrix with a continuous strand, swirl mat E-glass reinforcement was investigated for automotive applications. The material under stress was exposed to various automobile service environments. Results show that environment has substantial effects on its creep and creep-rupture properties. Proposed design guide lines and stress reduction factors were developed for various automotive environments. These composites are considered candidate structural materials for light weight and fuel efficient automobiles of the future.
Date:
December 31, 1998
Creator:
Ren, W. & Brinkman, C.R.
Object Type:
Report
System:
The UNT Digital Library
Critical mass analysis for {sup 235}U and {sup 239}Pu systems moderated and reflected by D{sub 2}O
Criticality dimensions for highly enriched {sup 235}U(93.5) and {sup 239}Pu(95.5) systems mixed with D{sub 2}O were studied. The objective of this work is to investigate the minimum critical mass and concentration of uranium and plutonium systems in a reflector-moderated arrangement. The present work demonstrates the critical instability of these systems that are moderated and reflected by D{sub 2}O and expands in previous unpublished work. These calculations were performed in a spherical geometry with the DANTS codes using the Hansen-Roach cross section library. Densities examined ranged from normal to very small, and are assumed to be uniform throughout the core. These spherical systems are reflected by 100 cm of D{sub 2}O.
Date:
December 31, 1998
Creator:
Loaiza, D. & Stratton, W.
Object Type:
Report
System:
The UNT Digital Library
CW RFQ fabrication and engineering
The design and fabrication of a four-vane RFQ to deliver a 100 mA CW proton beam at 6.7 MeV is described. This linac is an Oxygen-Free Electrolytic (OFE) copper structure 8 m in length and was fabricated using hydrogen furnace brazing as the joining technology.
Date:
December 31, 1998
Creator:
Schrage, D.; Young, L. & Roybal, P.
Object Type:
Article
System:
The UNT Digital Library
Cyclodextrin-based chemical microsensors for Volatile Organic Compounds (VOCs)
This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). This project addressed the development of surface-acoustic-wave (SAW)-based chemical sensors for remote, real-time sensing in air, groundwater, and possibly soil, of chlorinated and aromatic hydrocarbons using innovative molecular self-assembly techniques. Our goal is parts per billion (ppb) sensitivity to specific aromatic and chlorinated hydrocarbons using cyclodextrin as the selective layer of a SAW-based mass sensor. We have demonstrated that SAW sensors can differentiate between compounds with similar composition, structure, and polarity. These efforts, however, can be enhanced by using sensor arrays and smart data processing systems. Secondly, ionic interactions provide a convenient way to fabricate thin films for sensor applications. The potential of these thin films for sensor applications is currently being evaluated. 3 figs.
Date:
December 31, 1998
Creator:
Li, DeQuan
Object Type:
Report
System:
The UNT Digital Library
Damage evolution and clustering in shock loaded tantalum
Two grades of tantalum were shock loaded by plate impact and recovered. The loading conditions were varied to study the damage evolution in te materials from incipient to full spallation. The authors performed quantitative image analysis and optical profilometry on the recovered specimens. Statistical analyses are shown of the void sizes, void clustering, and void linking in the two material grades.
Date:
December 31, 1998
Creator:
Thissell, W.R.; Zurek, A.K.; Rivas, J.M.; Tonks, D.L. & Hixson, R.S.
Object Type:
Report
System:
The UNT Digital Library
Damage measurements on the NWTC direct-drive, variable-speed test bed
The NWTC (National Wind Technology Center) Variable-Speed Test Bed turbine is a three-bladed, 10-meter, downwind machine that can be run in either fixed-speed or variable-speed mode. In the variable-speed mode, the generator torque is regulated, using a discrete-stepped load bank to maximize the turbine`s power coefficient. At rated power, a second control loop that uses blade pitch to maintain rotor speed essentially as before, i.e., using the load bank to maintain either generator power or (optionally) generator torque. In this paper, the authors will use this turbine to study the effect of variable-speed operation on blade damage. Using time-series data obtained from blade flap and edge strain gauges, the load spectrum for the turbine is developed using rainflow counting techniques. Miner`s rule is then used to determine the damage rates for variable-speed and fixed-speed operation. The results illustrate that the controller algorithm used with this turbine introduces relatively large load cycles into the blade that significantly reduce its service lifetime, while power production is only marginally increased.
Date:
December 31, 1998
Creator:
Sutherland, H. J. & Carlin, P. W.
Object Type:
Article
System:
The UNT Digital Library
Data mining
This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to develop and implement data mining technology suited to the analysis of large collections of unstructured data. This has taken the form of a software tool, PADMA (Parallel Data Mining Agents), which incorporates parallel data accessing, parallel scalable hierarchical clustering algorithms, and a web-based user interface for submitting Structured Query Language (SQL) queries and interactive data visualization. The authors have demonstrated the viability and scalability of PADMA by applying it to an unstructured text database of 25,000 documents running on an IBM SP2 at Argonne National Laboratory. The utility of PADMA for discovering patterns in data has also been demonstrated by applying it to laboratory test data for Hepatitis C patients and autopsy reports in collaboration with the University of New Mexico School of Medicine.
Date:
December 31, 1998
Creator:
Lee, Kenneth; Kargupta, Hillol; Stafford, Brian G.; Buescher, Kevin L. & Ravindran, Binoy
Object Type:
Report
System:
The UNT Digital Library
Data/model integration for vertical mixing in the stable Arctic boundary layer
This is the final report of a short Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Data on atmospheric trace constituents and the vertical structure of stratus clouds from a 1996 expedition to the central Arctic reveal mechanisms of vertical mixing that have not been observed in mid-latitudes. Time series of the altitude and thickness of summer arctic stratus have been observed using an elastic backscatter lidar aboard an icebreaker. With the ship moored to the pack ice during 14 data collection stations and the lidar staring vertically, the time series represent advected cloud fields. The lidar data reveal a significant amount of vertical undulation in the clouds, strongly suggestive of traveling waves in the buoyantly damped atmosphere that predominates in the high Arctic. Concurrent observations of trace gases associated with the natural sulfur cycle (dimethyl sulfide, SO{sub 2}, NH{sub 3}, H{sub 2}O{sub 2}) and aerosols show evidence of vertical mixing events that coincide with a characteristic signature in the cloud field that may be called dropout or lift out. A segment of a cloud deck appears to be relocated from the otherwise quasicontinuous layer to another altitude a few hundred meters lower or higher. …
Date:
December 31, 1998
Creator:
Barr, S.; ReVelle, D. O.; Kao, C. Y. J. & Bigg, E. K.
Object Type:
Report
System:
The UNT Digital Library