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Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Trail of Lights
Photograph of a scene during the Trail of Lights event at the Duncan City Park.
Date:
December 11, 1999
Creator:
Argo, Jim
Object Type:
Photograph
System:
The Gateway to Oklahoma History
Proton Irradiation Effects in Oxide-Confined Vertical Cavity Surface Emitting Laser (VCSEL) Diodes
Recent space experience has shown that the use of commercial optocouplers can be problematic in spacecraft, such as TOPEX/Poseidon, that must operate in significant radiation environments. Radiation--induced failures of these devices have been observed in space and have been further documented at similar radiation doses in the laboratory. The ubiquitous use of optocouplers in spacecraft systems for a variety of applications, such as electrical isolation, switching and power transfer, is indicative of the need for optocouplers that can withstand the space radiation environment. In addition, the distributed nature of their use implies that it is not particularly desirable to shield optocouplers for use in radiation environments. Thus, it will be important for the space community to have access to radiation hardened/tolerant optocouplers. For many microelectronic and photonic devices, it is difficult to achieve radiation hardness without sacrificing performance. However, in the case of optocouplers, one should be able to achieve both superior radiation hardness and performance for such characteristics as switching speed, current transfer ratio (CTR), minimum power usage and array power transfer, if standard light emitting diodes (LEDs), such as those in the commercial optocouplers mentioned above, are avoided, and VCSELs are employed as the emitter portion of the …
Date:
March 11, 1999
Creator:
Armendariz, M. G.; Barnes, C. E.; Choquette, K. D.; Guertin, S.; Hash, G. L.; Schwank, J. R. et al.
Object Type:
Article
System:
The UNT Digital Library
LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL
''Conventional'' waste landfills emit methane, a potent greenhouse gas, in quantities such that landfill methane is a major factor in global climate change. Controlled landfilling is a novel approach to manage landfills for rapid completion of total gas generation, maximizing gas capture and minimizing emissions of methane to the atmosphere. With controlled landfilling, methane generation is accelerated and brought to much earlier completion by improving conditions for biological processes (principally moisture levels) in the landfill. Gas recovery efficiency approaches 100% through use of surface membrane cover over porous gas recovery layers operated at slight vacuum. A field demonstration project's results at the Yolo County Central Landfill near Davis, California are, to date, highly encouraging. Two major controlled landfilling benefits would be the reduction of landfill methane emissions to minuscule levels, and the recovery of greater amounts of landfill methane energy in much shorter times than with conventional landfill practice. With the large amount of US landfill methane generated, and greenhouse potency of methane, better landfill methane control can play a substantial role in reduction of US greenhouse gas emissions.
Date:
January 11, 1999
Creator:
Augenstein, Don
Object Type:
Report
System:
The UNT Digital Library
First Lasing of a High-Gain Harmonic Generation Free-Electron Laser Experiment.
We report on the first lasing of a high-gain harmonic generation (HGHG) free-electron laser (FEL). The experiment was conducted at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL). This is a BNL experiment in collaboration with the Advanced Photon Source (APS) at Argonne National Laboratory. A preliminary measurement gives a high-gain harmonic generation (HGHG) pulse energy that is 2 x 10{sup 7} times larger than the spontaneous radiation, In a purely self-amplified spontaneous emission (SASE) mode of operation, the signal was measured as 10 times larger than the spontaneous radiation in the same distance ({approximately}2 m) through the same wiggler. This means the HGHG signal is 2 x 10{sup 6} times larger than the SASE signal. To obtain the same saturated output power by the SASE process, the radiator would have to be 3 times longer (6 m).
Date:
September 11, 1999
Creator:
Babzien, M.; Ben-Zvi, Ilan; Biedron, S. G.; DiMauro, L. F.; Douryan, A.; Galayda, J. N. et al.
Object Type:
Article
System:
The UNT Digital Library
Transport, Growth Mechanisms, and Material Quality in GaN Epitaxial Lateral Overgrowth
Growth kinetics, mechanisms, and material quality in GaN epitaxial lateral over-growth (ELO) were examined using a single mask of systematically varied patterns. A 2-D gas phase reaction/diffusion model describes how transport of the Ga precursor to the growth surface enhances the lateral rate in the early stages of growth. In agreement with SEM studies of truncated growth runs, the model also predicts the dramatic decrease in the lateral rate that occurs as GaN over-growth reduces the exposed area of the mask. At the point of convergence, a step-flow coalescence mechanism is observed to fill in the area between lateral growth-fronts. This alternative growth mode in which a secondary growth of GaN is nucleated along a single convergence line, may be responsible for producing smooth films observed to have uniform cathodoluminescence (CL) when using 1{micro}m nucleation zones. Although emission is comprised of both UV ({approximately}365nm) and yellow ({approximately}550nm) components, the spectra suggest these films have reduced concentrations of threading dislocations normally associated with non-radiative recombination centers and defects known to accompany growth-front convergence lines.
Date:
January 11, 1999
Creator:
Baca, Albert G.; Bartram, M. E.; Coltrin, M. E.; Crawford, M. H.; Han, J.; Missert, N. et al.
Object Type:
Article
System:
The UNT Digital Library
Effect of interior surface finish on the break-up of commercial shaped charge liners
A series of experiments aimed at understanding the influence of the liner interior surface finish on the break-up of shaped charge jets has been completed. The experiments used a standard 81-mm shaped charge design, loaded with LX-14 high explosive; incorporating high-precision copper shaped charged liners. The results indicate that a significant reduction of jet break-up time occurs between a surface finish of 99.30 microinches and 375.65 microinches. Surface finishes of 4.78, 44.54 and 99.30 microinches produced significantly better ductility and associated break-up times than the 375.65-microinch finish. The baseline production process high-precision liners were measured to have an average surface finish of 44.54 microinches. The results show that for the shaped charge warhead geometry and explosive combination investigated, some care must be taken in respect to surface finish, but that very fine surface finishes do not significantly improve the jet ductility and associated break-up times.
Date:
August 11, 1999
Creator:
Baker, E L & Schwartz, A J
Object Type:
Article
System:
The UNT Digital Library
Steam generator mock-up for assessment of inservice inspection technology.
A steam generator mock-up has been assembled for round-robin studies of the effectiveness of currently practiced inservice inspection (ISI) technology for detection of current-day flaws. The mock-up will also be used to evaluate emerging inspection technologies. The 3.66-m (12-ft.)-tall mock-up contains 400 tube openings, each consisting of 9 test sections that can be used to simulate current-day field-induced flaws and artifacts. Included in the mock-up are simulations of tube support plate (TSP) intersections and the tube sheet (TS). Cracks are present at the TSP, TS, and in the free span sections of the mock-up. For initial evaluation of the round-robin results, various eddy current methods, as well as multivariate models for data analysis techniques, are being used to estimate the depth and length of defects in the mock-up. To ensure that the round-robin is carried out with procedures as close as possible to those implemented in the field, input was obtained from industry experts on the protocol and procedures to be used for the exercise. One initial assembly of the mock-up with a limited number of flaws and artifact has been completed and tested. A second completed configuration with additional flaw and artifacts simulations will be used for the round-robin.
Date:
September 11, 1999
Creator:
Bakhtiari, S.; Kupperman, D. S. & Muscara, J.
Object Type:
Article
System:
The UNT Digital Library
Parametric Instabilities in Laser/Matter Interaction: From Noise Levels to Relativistic Regimes
The purpose of this LDRD was the study of parametric instabilities on a laser-produced plasma, addressing crucial issues affecting the coupling between the laser and the plasma. We have made very good progress during these three years, in advancing our understanding in many different fronts. Progress was made in both theoretical and experimental areas. The coupling of high-power laser light to a plasma through scattering instabilities is still one of the most complex processes in laser-plasma interaction physics. In spite of the relevance of these parametric processes to inertial confinement fusion (ICF) and all other situations where a high-power laser beam couples to a plasma, many aspects of the interaction remain unexplained, even after many years of intensive experimental and theoretical efforts. Important instabilities under study are stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and the Langmuir decay instability (LDI). The study of these instabilities is further complicated by the competition and interplay between them, and, in the case of ICF, by the presence of multiple overlapping interaction beams. Stimulated Brillouin scattering consists of the decay of the incident electromagnetic (EM) wave into a scattered EM wave and an ion acoustic wave (IAW). Similarly, SRS consists of the decay …
Date:
February 11, 1999
Creator:
Baldis, H. A.; Kruer, W. L. & Labaune, C. L.
Object Type:
Report
System:
The UNT Digital Library
Development of a composite-reinforced aluminum conductor
Fact sheet written for the Inventions and Innovation Program about a new composite-reinforced aluminum conductor for utility transmission and distribution. The millions of people affected by a blackout in the western US, Canada, and parts of Mexico in July 1996 had no idea the power outage was caused by overloaded transmission lines sagging low enough to touch trees. Millions of New Englanders affected by power outages during the 1997--98 winter probably weren't aware that accumulations of ice and snow on transmission lines had caused the lines to snap. Yet, these two examples illustrate the urgent need to begin upgrading this country's aging electrical-power distribution systems. A key step in this process lies in improving the weight and conductivity characteristics of utility transmission and distribution lines. Conventional conductors used for overhead transmission and distribution lines are comprised of aluminum strands of wire wrapped around a steel core. The aluminum serves as the electrical conductor, while the steel provides mechanical support. This hybrid design results in an excellent weight-to-conductivity ratio, but it also yields a heavier product, which requires stronger and more costly support structures and limits conductivity. W. Brandt Goldsworthy and Associates, Inc., of Torrance, California, is developing a new composite-reinforced …
Date:
November 11, 1999
Creator:
Balsam, J.
Object Type:
Book
System:
The UNT Digital Library
News Bulletin (Castroville, Tex.), Vol. [41], No. [10], Ed. 1 Thursday, March 11, 1999
Weekly newspaper from Castroville, Texas that includes local, state, and national news along with extensive advertising.
Date:
March 11, 1999
Creator:
Barnes, Thomas
Object Type:
Newspaper
System:
The Portal to Texas History
News Bulletin (Castroville, Tex.), Vol. 41, No. 45, Ed. 1 Thursday, November 11, 1999
Weekly newspaper from Castroville, Texas that includes local, state, and national news along with extensive advertising.
Date:
November 11, 1999
Creator:
Barnes, Thomas
Object Type:
Newspaper
System:
The Portal to Texas History
The intermediate silicon layers space Fframe
The Intermediate Silicon Layers (ISL) detector is being built as part of the Collider Detector at Fermilab (CDF) upgrades for the run II operation of Tevatron. The ISL Space Frame (SF) is a structure that defines the location of the ISL detectors, supports the micro-vertex silicon trackers (SVXII, L00) as well as the beryllium beam pipe. The SF design, project and construction is challenging due to the precision and mechanical stability requirements that must be achieved using a minimum amount of material. The SF is a high precision light structure made in carbon fiber designed and built at the INFN Pisa and shipped at Fermilab in summer 1999. In this contribution we describe in detail the SF construction phase and the accuracy obtained.
Date:
November 11, 1999
Creator:
Basti, A.; Bedeschi, F.; Demina, R.; Gaggelli, A. & Goldstein, J.
Object Type:
Article
System:
The UNT Digital Library