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Ensemble: 2001-11-08 - African Percussion Ensemble
Access:
Use of this item is restricted to the UNT Community
Ensemble performance at the UNT College of Music Concert Hall.
Date:
November 8, 2001
Creator:
African Percussion Ensemble
Object Type:
Sound
System:
The UNT Digital Library
A New Dynamical Diffraction-Based Technique of the Residual Stress Measurements in Thin Films
The recently discovered dynamical diffraction effect ''neutron camel'' was used for the residual stress measurements in a thick Si(111) crystal coated with a 2000 {angstrom} thick Ni film. The observed asymmetry of the back-face rocking curve corresponds to the bending radius of {approx} 19 km and the tension force applied to the Ni film is {approx} 90 N/m. Relative deformation of the Si crystallographic cells in the vicinity of diffractive surfaces is |{partial_derivative}u{sub z}/{partial_derivative}z| {approx} 1.6 x 10{sup -6}.
Date:
July 26, 2001
Creator:
Agamalian, M.
Object Type:
Article
System:
The UNT Digital Library
An integrated solution for secure group communication in wide-area networks
Many distributed applications require a secure reliable group communication system to provide coordination among the application components. This paper describes a secure group layer (SGL) which bundles a reliable group communication system, a group authorization and access control mechanism, and a group key agreement protocol to provide a comprehensive and practical secure group communication platform. SGL also encapsulates the standard message security services (i.e, confidentiality, authenticity and integrity). A number of challenging issues encountered in the design of SGL are brought to light and experimental results obtained with a prototype implementation are discussed.
Date:
April 1, 2001
Creator:
Agarwal, Deborah A.; Chevassut, Olivier; Thompson, Mary & Tsudik, Gene
Object Type:
Article
System:
The UNT Digital Library
Network aware distributed applications
Most distributed applications today manage to utilize only a small percentage of the needed and available network bandwidth. Often application developers are not aware of the potential bandwidth of the network, and therefore do not know what to expect. Even when application developers are aware of the specifications of the machines and network links, they have few resources that can help determine why the expected performance was not achieved. What is needed is a ubiquitous and easy-to-use service that provides reliable, accurate, secure, and timely estimates of dynamic network properties. This service will help advise applications on how to make use of the network's increasing bandwidth and capabilities for traffic shaping and engineering. When fully implemented, this service will make building currently unrealizable levels of network awareness into distributed applications a relatively mundane task. For example, a remote data visualization application could choose between sending a wireframe, a pre-rendered image, or a 3-D representation, based on forecasts of CPU availability and power, compression options, and available bandwidth. The same service will provide on-demand performance information so that applications can compare predicted with actual results, and allow detailed queries about the end-to-end path for application and network tuning and debugging.
Date:
February 4, 2001
Creator:
Agarwal, Deborah; Tierney, Brian L.; Gunter, Dan; Lee, Jason & Johnston, William
Object Type:
Article
System:
The UNT Digital Library
Final progress report on Grant No. DE-FG02-81ER10229, U.S. Department of Energy Reactor Sharing Program at the University of Wisconsin, July 15, 2000 - May 31, 2001
The Reactor Sharing Program makes the facilities of the University of Wisconsin Nuclear Reactor Laboratory available to other educational institutions. Uses include direct instruction, student theses projects, and staff research projects. A list of using institutions and a brief description of use is given.
Date:
December 27, 2001
Creator:
Agasie, Robert J.
Object Type:
Report
System:
The UNT Digital Library
Trade and the Americas
None
Date:
November 9, 2001
Creator:
Ahearn, Raymond J.
Object Type:
Report
System:
The UNT Digital Library
Trade Legislation in the 106th Congress: An Overview
The 106th Congress completed action on a number of major trade initiatives. The impact on American firms and workers was a paramount concern in the passage of this legislation. Most notably, bills were passed to establish "normal trade relations" with China, deepen economic ties with the countries of Sub-Saharan Africa, enhance trade benefits for 24 Caribbean Basin countries, and to ease trade sanctions on Cuba and other countries. Congress also voted to maintain U.S. participation in the World Trade Organization (WTO), as well as worked with the Clinton Administration to pass replacement legislation for the Foreign Sales Corporation (FSC) tax benefit for U.S. exports. The latter action averted, at least until mid-2001, the imposition of punitive tariffs by the European Union on an estimated $4 billion in U.S. exports.
Date:
March 7, 2001
Creator:
Ahearn, Raymond J. & Jones, Vivian C.
Object Type:
Report
System:
The UNT Digital Library
RF Gas Plasma Source Development for Heavy Ion Fusion
Presently the Heavy Ion Fusion Virtual National Laboratory is researching ion sources and injector concepts to understand how to optimize beam brightness over a range of currents (50-2000 mA argon equivalent). One concept initially accelerates millimeter size, milliamp beamlets to 1 MeV before merging them into centimeter size, ampere beams. Computer simulations have shown the final brightness of the merged beams is dominated by the emittance growth of the merging process, as long as the beamlets ion temperature is below a few eV. Thus, a RF multicusp source capable of high current density can produce beams with better brightness compared to ones extracted from a colder source with a large aperture and lower current density. As such, experiments have begun to develop a RF multicusp source capable of delivering one amp of extracted beam current. It is expected that it will require 10 kW of 13 MHz RF power delivered via a quartz shielded, one and half turn, four inch diameter antenna. Important considerations in the development of the source include the dependence of current density and beam ion temperature on consumed RF power and gas pressure. A fast rise time ({approx} 100 ns) for the extracted beam pulse must …
Date:
September 4, 2001
Creator:
Ahle, L.; Hall, R. P.; Molvik, A. W.; Kwan, J. W. & Leung, K. N.
Object Type:
Article
System:
The UNT Digital Library
Unsaturated Zone Flow Patterns and Analysis
This Analysis/Model Report (AMR) documents the development of an expected-case model for unsaturated zone (UZ) flow and transport that will be described in terms of the representativeness of models of the natural system. The expected-case model will provide an evaluation of the effectiveness of the natural barriers, assess the impact of conservatism in the Total System Performance Assessment (TSPA), and support the development of further models and analyses for public confidence building. The present models used in ''Total System Performance Assessment for the Site Recommendation'' (Civilian Radioactive Waste Management System Management and Operating Contractor (CRWMS M&O) 2000 [1532461]) underestimate the natural-barrier performance because of conservative assumptions and parameters and do not adequately address uncertainty and alternative models. The development of an expected case model for the UZ natural barrier addresses issues regarding flow-pattern analysis and modeling that had previously been treated conservatively. This is in line with the Repository Safety Strategy (RSS) philosophy of treating conservatively those aspects of the UZ flow and transport system that are not important for achieving regulatory dose (CRWMS M&O 2000 [153246], Section 1.1.1). The development of an expected case model for the UZ also provides defense-in-depth in areas requiring further analysis of uncertainty and …
Date:
October 17, 2001
Creator:
Ahlers, C.
Object Type:
Report
System:
The UNT Digital Library
Impact of Rock Bolts on Seepage
Characterization of seepage into drifts in unsaturated fractured tuff is a key factor for assessing the long-term viability of the proposed high level nuclear waste repository at Yucca Mountain. Rock bolts are among the methods proposed for ground control in the emplacement drifts. They may provide a conduit whereby percolating water that would otherwise bypass the drift will seep into the drift. The objective of this study is to assess the impact that the use of rock bolts may have on seepage. The impact of rock bolts on seepage is studied using a numerical model that is finely discretized around the rock bolt. There are several sources of uncertainty and variability with respect to the flow system around the drift and rock bolt. There is uncertainty about the capillary strength of the fractures around the drift. There is also uncertainty about how the permeability and capillary strength of the grout used to cement the steel rock bolts into the bolt holes will change over time. There is variability expected in the percolation rates incident upon the drifts depending on location. The uncertainty and variability of these parameters are approached by evaluating the rock bolt impact over a range of values …
Date:
June 1, 2001
Creator:
Ahlers, F. C.
Object Type:
Report
System:
The UNT Digital Library
Structure and spectroscopy of transcurium nuclei.
The stability of the superheavy elements depends on the shell corrections which are governed by the single-particle spectra. Ideally one would like to experimentally determine the single-particle levels in the superheavy nuclei but the production of only a few atoms of these nuclides precludes such measurements. One therefore has to identify single-particle levels in the heaviest nuclei which are available in at least nanoCurie amounts. They have studied the structure of such heavy nuclei in the Z=98 region and identified many single-particle states. In particular, they have studied the structure of {sup 251}Cf and {sup 249}Bk by measuring the radiations emitted in the {alpha} decay of {sup 255}Fm and {sup 253}Es. These single-particle spectra can be used to test theoretical models for superheavy elements.
Date:
November 9, 2001
Creator:
Ahmad, I.
Object Type:
Article
System:
The UNT Digital Library
Neutrino Observations From the Sudbury Neutrino Observatory
The Sudbury Neutrino Observatory (SNO) is a water imaging Cherenkov detector. Its usage of 1000 metric tons of D{sub 2}O as target allows the SNO detector to make a solar-model independent test of the neutrino oscillation hypothesis by simultaneously measuring the solar {nu}{sub e} flux and the total flux of all active neutrino species. Solar neutrinos from the decay of {sup 8}B have been detected at SNO by the charged-current (CC) interaction on the deuteron and by the elastic scattering (ES) of electrons. While the CC reaction is sensitive exclusively to {nu}{sub e}, the ES reaction also has a small sensitivity to {nu}{sub {mu}} and {nu}{sub {tau}}. In this paper, recent solar neutrino results from the SNO experiment are presented. It is demonstrated that the solar flux from {sup 8}B decay as measured from the ES reaction rate under the no-oscillation assumption is consistent with the high precision ES measurement by the Super-Kamiokande experiment. The {nu}{sub e} flux deduced from the CC reaction rate in SNO differs from the Super-Kamiokande ES results by 3.3{sigma}. This is evidence for an active neutrino component, in additional to {nu}{sub e}, in the solar neutrino flux. These results also allow the first experimental determination …
Date:
September 24, 2001
Creator:
Ahmad, Q. R.; Allen, R. C.; Andersen, T. C.; Anglin, J. D.; Barton, J. C.; Beier, E. W. et al.
Object Type:
Article
System:
The UNT Digital Library
Advanced Computational Model for Three-Phase Slurry Reactors Progress Report: October 2001
In the second year of the project, the Eulerian-Lagrangian formulation for analyzing three-phase slurry flows in a bubble column is further developed. The approach uses an Eulerian analysis of liquid flows in the bubble column, and makes use of the Lagrangian trajectory analysis for the bubbles and particle motions. An experimental set for studying a two-dimensional bubble column is also developed. The operation of the bubble column is being tested and diagnostic methodology for quantitative measurements is being developed. An Eulerian computational model for the flow condition in the two-dimensional bubble column is also being developed. The liquid and bubble motions are being analyzed and the results are being compared with the experimental setup. Solid-fluid mixture flows in ducts and passages at different angle of orientations were analyzed. The model predictions were compared with the experimental data and good agreement was found. Gravity chute flows of solid-liquid mixtures is also being studied. Further progress was also made in developing a thermodynamically consistent model for multiphase slurry flows with and without chemical reaction in a state of turbulent motion. The balance laws are obtained and the constitutive laws are being developed. Progress was also made in measuring concentration and velocity of …
Date:
October 1, 2001
Creator:
Ahmadi, Goodarz
Object Type:
Report
System:
The UNT Digital Library
Integrated fuel processor development.
The Department of Energy's Office of Advanced Automotive Technologies has been supporting the development of fuel-flexible fuel processors at Argonne National Laboratory. These fuel processors will enable fuel cell vehicles to operate on fuels available through the existing infrastructure. The constraints of on-board space and weight require that these fuel processors be designed to be compact and lightweight, while meeting the performance targets for efficiency and gas quality needed for the fuel cell. This paper discusses the performance of a prototype fuel processor that has been designed and fabricated to operate with liquid fuels, such as gasoline, ethanol, methanol, etc. Rated for a capacity of 10 kWe (one-fifth of that needed for a car), the prototype fuel processor integrates the unit operations (vaporization, heat exchange, etc.) and processes (reforming, water-gas shift, preferential oxidation reactions, etc.) necessary to produce the hydrogen-rich gas (reformate) that will fuel the polymer electrolyte fuel cell stacks. The fuel processor work is being complemented by analytical and fundamental research. With the ultimate objective of meeting on-board fuel processor goals, these studies include: modeling fuel cell systems to identify design and operating features; evaluating alternative fuel processing options; and developing appropriate catalysts and materials. Issues and outstanding …
Date:
December 4, 2001
Creator:
Ahmed, S.; Pereira, C.; Lee, S. H. D. & Krumpelt, M.
Object Type:
Article
System:
The UNT Digital Library
GEM-type detectors using LIGA and etchable glass technologies
Gas electron multipliers (GEMS) have been made by a deep X-ray lithography technique (LIGA process) using synchrotron radiation on polymethylmethacrylate (PMMA) and by UV processes using a UV etchable glass. Gain, stability and rate capability for these detectors are described.The LIGA detectors described consist of PMMA sheets of various thicknesses, 125mm to 350mm, and have 150mm x 150mm square holes spaced with a pitch of 300mm. Thin copper electrodes are plated on the top and bottom surfaces using a Damascene method, followed by electroless plating of the copper onto a palladium-tin base layer. For various thicknesses of PMMA measurements have been made of absolute gain vs. voltage, time stability of gain, and rate capability. The operating gas mixture was usually Ar/CO2 (70/30) gas, but some tests were also done using P10 gas. We also made GEM-like detectors using the UV etchable glass called Foturan, patterned by exposure to UV light and subsequent etching. A few measurements using these detectors will be reported, including avalanche gain and time stability.
Date:
November 2, 2001
Creator:
Ahn, S. K.; Kim, J. G.; Perez-Mendez, V.; Chang, S.; Jackson, K. H.; Kadyk, J. A. et al.
Object Type:
Article
System:
The UNT Digital Library
Rhapsody for Piano and Small Orchestra
Rhapsody for Piano and Small Orchestra is a one-movement composition in a concerto fashion for seventeen players, and is about nine minutes in duration. The overall form of this work is A B C D E D1 C1 B1 A1. This work contains various hidden compositional devices such as the golden section principle and a palindrome structure. These devices are applied not only to the structure of the work, but also to the pitch related and rhythm-related matters. Also, certain melodic and rhythmic cells are employed for each section in the developmental procedure of that section almost exclusively. Since this work is a concerto-like piece, there are two cadenza-like passages for the piano with an accompanying solo instrument, which plays the obbligato passage. The following essay addresses the form, pitch materials, harmony, rhythm and technical difficulties, orchestration, and variant elements between the corresponding sections used in this work.
Date:
December 2001
Creator:
Ahn-Kim, Yong Hee
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Measurement of Recombination Parameters of Photovoltaic Materials by Resonant-Coupled Photoconductive Decay: Preprint
Presented at the 2001 NCPV Program Review Meeting: Novel contactless measurement technique that provides minority carrier lifetime, ambipolar mobility, and diffusion length.
Date:
October 1, 2001
Creator:
Ahrenkiel, R. & Johnston, S.
Object Type:
Article
System:
The UNT Digital Library
STATUS AND RECENT PERFORMANCE OF THE ACCELERATORS THAT SERVE AS GOLD INJECTOR FOR RHIC.
The recent successful commissioning and operation [1] of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) requires the injection of gold ions of specified energy and intensity with longitudinal and transverse emittances small enough to meet the luminosity requirements of the collider. Ion beams with the desired characteristics are provided by a series of three accelerators, the Tandem, Booster and AGS. The current status and recent performance of these accelerators are reviewed in this paper.
Date:
June 18, 2001
Creator:
Ahrens, L.; Alessi, J.; Van Asselt, W.; Benjamin, J.; Blaskiewicz, M.; Brennan, J. M. et al.
Object Type:
Article
System:
The UNT Digital Library
Systems Requirement Document for the MSRE U-233 Conversion System
The fissile material reclamation activities for the MSRE remediation project include the removal and recovery of uranium from the off-gas system, from the stored fuel salt, and finally, from the uranium-laden charcoal in the Auxiliary Charcoal Bed (ACB). Each of these operations produces an uranium/fluoride compound that is not suitable for long-term storage. The uranium-fluoride compounds can be stored for a limited period of time in pressure vessels. The interim-storage vessels are designed to handle the internal pressure buildup from gases formed by radiolysis of the uranium-fluoride compounds. The conversion process will take the pressurized vessels from interim storage and process the materials in a hot cell located at Building 4501. The gas in the vessels will be vented through chemical traps and then the traps will be processed to convert the various uranium-fluoride compounds to a stable uranium oxide form. This will be done one trap at a time. The chemical form of uranium being extracted from the off-gas system and from fuel salt fluorination process is uranium hexafluoride UF{sub 6}. During the operations at MSRE, the UF{sub 6} is chemisorbed onto sodium fluoride (NaF) traps where it forms the complex, 2NaF{center_dot}UF{sub 6}. The conversion process that will be …
Date:
January 11, 2001
Creator:
Aigner, R. D.
Object Type:
Report
System:
The UNT Digital Library
Paleo-Climate and Glaciological Reconstruction in Central Asia through the Collection and Analysis of Ice Cores and Instrumental Data from the Tien Shan
While the majority of ice core investigations have been undertaken in the polar regions, a few ice cores recovered from carefully selected high altitude/mid-to-low latitude glaciers have also provided valuable records of climate variability in these regions. A regional array of high resolution, multi-parameter ice core records developed from temperate and tropical regions of the globe can be used to document regional climate and environmental change in the latitudes which are home to the vase majority of the Earth's human population. In addition, these records can be directly compared with ice core records available from the polar regions and can therefore expand our understanding of inter-hemispheric dynamics of past climate changes. The main objectives of our paleoclimate research in the Tien Shan mountains of middle Asia combine the development of detailed paleoenvironmental records via the physical and chemical analysis of ice cores with the analysis of modern meteorological and hydrological data. The first step in this research was the collection of ice cores from the accumulation zone of the Inylchek Glacier and the collection of meteorological data from a variety of stations throughout the Tien Shan. The research effort described in this report was part of a collaborative effort with …
Date:
May 30, 2001
Creator:
Aizen, Vladimir; Bren, Donald; Kreutz, Karl & Wake, Cameron
Object Type:
Report
System:
The UNT Digital Library
Variation of nominal contact pressure with time during sliding wear.
None
Date:
April 9, 2001
Creator:
Ajayi, O. O. & Erck, R. A.
Object Type:
Article
System:
The UNT Digital Library
Effect of thin-film coating on wear in EGR-contaminated oil.
Increased use of higher-efficiency compression ignition direct injection (CIDI) diesel engines instead of today's gasoline engines will result in reduced fuel consumption and greenhouse gases emissions. However, NO{sub x} and particulate exhaust emissions from diesel engines must be significantly reduced due to their possible adverse health effects. Exhaust gas recirculation (EGR) is an effective way to reduce NO{sub x} emissions from diesel engines, but the particulates and acidic exhaust products in the recirculated gas will contaminate engine lubricant oil by increasing the soot content and total acid number (TAN). These factors will increase the wear rate in many critical engine components and seriously compromise engine durability. We have investigated the use of commercially available thin and hard coatings (TiN, TiCN, TiAlN, and CrN) to mitigate the negative effects of EGR on wear. In tests with the four-ball machine according to ASTM D4172, we found that all the four coatings deposited on M-50 steel significantly reduced wear in EGR-contaminated oils when compared with uncoated M50 steel balls.
Date:
December 6, 2001
Creator:
Ajayi, O. O.; Aldajah, S. H.; Erdemir, A. & Fenske, G. R.
Object Type:
Article
System:
The UNT Digital Library
Performance of amorphous carbon coating in turbocompressor air bearings.
None
Date:
December 6, 2001
Creator:
Ajayi, O. O.; Woodford, J. B.; Erdemir, A. & Fenske, G. R.
Object Type:
Article
System:
The UNT Digital Library
Characterizing the fabric of the urban environment: A case study of Salt Lake City, Utah
Urban fabric data are needed in order to estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city, and to design effective implementation programs. In this report, we discuss the result of a semi-automatic Monte-Carlo statistical approach used to develop data on surface-type distribution and city-fabric makeup (percentage of various surface-types) using aerial color orthophotography. The digital aerial photographs for Salt Lake City covered a total of about 34 km2 (13 mi2). At 0.50-m resolution, there were approximately 1.4 x 108 pixels of data. Four major land-use types were examined: (1) commercial, (2) industrial, (3) educational, and (4) residential. On average, for the areas studied, vegetation covers about 46 percent of the area (ranging 44-51 percent), roofs cover about 21 percent (ranging 15-24 percent), and paved surfaces about 26 percent (ranging 21-28 percent). For the most part, trees shade streets, parking lots, grass, and sidewalks. In most non-residential areas, paved surfaces cover 46-66 percent of the area. In residential areas, on average, paved surfaces cover about 32 percent of the area. Land-use/land-cover (LU/LC) data from the United States Geological Survey were used to extrapolate these results …
Date:
February 28, 2001
Creator:
Akbari, Hashem & Rose, L. Shea
Object Type:
Report
System:
The UNT Digital Library