Partner
UNT Libraries Government Documents Department
1,028
Oklahoma Historical Society
150
UNT Libraries Special Collections
61
UNT Music Library
29
Sterling Municipal Library
27
Carl Albert Congressional Research and Studies Center
22
Rice University Woodson Research Center
15
UNT Libraries
14
Alvin Community College
12
Abilene Christian University Library
10
72 More
Collection
Office of Scientific & Technical Information Technical Reports
812
Texas Digital Newspaper Program
347
Oklahoma Digital Newspaper Program
163
Tocker Foundation Grant
152
Government Accountability Office Reports
133
College of Music Recordings
29
Texas State Publications
28
Chickasha Newspaper Collection
27
Congressional Research Service Reports
27
Altus Times-Democrat
26
127 More
Degree Department
Degree Discipline
Degree Level
Country
Year
Month
Results:
1 - 24 of
1,672
next
Impact of the LHC beam abort kicker prefire on high luminosity insertion and CMS detector performance
The effect of possible accidental beam loss in LHC on the IP5 insertion elements and CMS detector is studied via realistic Monte Carlo simulations. Such beam loss could be the consequence of an unsynchronized abort or � in worst case � an accidental prefire of one of the abort kicker modules. Simulations with the STRUCT code show that this beam losses would take place in the IP5 inner and outer triplets. MARS simulations of the hadronic and electro-magnetic cascades induced in such an event indicate severe heating of the inner triplet quadrupoles. In order to protect the IP5 elements, two methods are proposed: a set of shadow collimators in the outer triplet and a prefired module compensation using a special module charged with an opposite voltage (antikicker). The remnants of the accidental beam loss entering the experimental hall have been used as input for FLUKA simulations in the CMS detector. It is shown that it is vital to take measures to reliably protect the expensive CMS tracker components.
Date:
April 13, 1999
Creator:
A.I. Drozhdin, N.V. Mokhov and M. Huhtinen
Object Type:
Article
System:
The UNT Digital Library
On possible use of bent crystal to improve Tevatron beam scraping
A possibility to improve the Tevatron beam halo scraping using a bent channeling crystal instead of a thin scattering primary collimator is studied. To evaluate the efficiency of the system, realistic simulations have been performed using the CATCH and STRUCT Monte Carlo codes. It is shown that the scraping efficiency can be increased and the accelerator-related backgrounds in the CDF and DØ collider detectors can be reduced by about one order of magnitude. Results on scraping efficiency versus thickness of amorphous layer of the crystal, crystal alignment and its length are presented.
Date:
April 8, 1999
Creator:
A.I. Drozhdin, N.V. Mokhov and V.M. Biryukov
Object Type:
Article
System:
The UNT Digital Library
Radiation environment resulting from Main Injector beam extraction to the NuMI beam line
A 120 GeV Main Injector proton beam will be delivered to the NuMI beam line at Fermilab at the rate of 3.7x 10{sup 20} per year. Realistic Monte Carlo simulations have been performed to examine the radiation environment in the beam extraction system and NuMI beam line elements. A complete 3-D model of the 160 meter extraction region has been implemented utilizing the computer code MARS. The model includes a description of the field of the electrostatic septa and POISSON calculated field maps of the Lambertson magnets and the other lattice components in the area. The beam element alignment and the source term have been simulated using the code STRUCT. Results on beam losses in the system, energy deposition in the core elements and residual dose rates on the components are presented.
Date:
April 29, 1999
Creator:
A.I. Drozhdin, P.W. Lucas, N.V. Mokhov, C.D. Moore and S.I. Striganov
Object Type:
Article
System:
The UNT Digital Library
Plutonium reclamation facility (PRF), building 236-Z layup plan
This document reviews each system inside PRF to determine the operation and maintenance requirements necessary to maintain safe and predictable system performance for facility systems needed to remain operational while minimizing the maintenance and surveillance being performed. Also covered are the actions required to place PRF in a safe layup configuration while minimizing hazards and taking into account the need for reactivation of certain equipment when cleanup work commences in the future.
Date:
April 6, 1999
Creator:
ANDERSON, R.N.
Object Type:
Report
System:
The UNT Digital Library
Chamber and target technology development for inertial fusion energy
Fusion chambers and high pulse-rate target systems for inertial fusion energy (IFE) must: regenerate chamber conditions suitable for target injection, laser propagation, and ignition at rates of 5 to 10 Hz; extract fusion energy at temperatures high enough for efficient conversion to electricity; breed tritium and fuel targets with minimum tritium inventory; manufacture targets at low cost; inject those targets with sufficient accuracy for high energy gain; assure adequate lifetime of the chamber and beam interface (final optics); minimize radioactive waste levels and annual volumes; and minimize radiation releases under normal operating and accident conditions. The primary goal of the US IFE program over the next four years (Phase I) is to develop the basis for a Proof-of-Performance-level driver and target chamber called the Integrated Research Experiment (IRE). The IRE will explore beam transport and focusing through prototypical chamber environment and will intercept surrogate targets at high pulse rep-rate. The IRE will not have enough driver energy to ignite targets, and it will be a non-nuclear facility. IRE options are being developed for both heavy ion and laser driven IFE. Fig. 1 shows that Phase I is prerequisite to an IRE, and the IRE plus NIF (Phase II) is prerequisite …
Date:
April 7, 1999
Creator:
Abdou, M.; Besenbruch, G.; Duke, J.; Forman, L.; Goodin, D.; Gulec, K. et al.
Object Type:
Report
System:
The UNT Digital Library
Pattern of Thermal Fluctuations in a Recovery Boiler Floor
The floor of a black liquor recovey boiler at a mill in central Canada has experienced cracking and delamination of the composite tubing near the spout wall and deformation of the floor panels that is most severe in the vicinity of the spout wall. One possible explanation for the observed damage is impacts of salt cake falling from the convective section onto the floor. In order to determine if such impacts do occur, strain gauges and thermocouples were installed on the boiler floor in areas where cracking and deformation were most frequent. The data obtained from these instruments indicate that brief, sudden temperature fluctuations do occur, and changes in the strain experienced by the affected tube occur simultaneously. These fluctuations appear to occur less often along the spout wall and more frequently with increasing distance from the wall. The frequency of these temperature fluctuations is insufficient for thermal fatigue to be the sole cause of the cracking observed on the tubes, but the data are consistent with what might be expected from pieces of falling salt cake.
Date:
April 25, 1999
Creator:
Abdullah, Z.; Gorog, J. P.; Keiser, J. R.; Meyers, L. E. & Swindeman, R. W.
Object Type:
Article
System:
The UNT Digital Library
Abilene Philharmonic Playbill: April 10-May 1, 1999
Program for an Abilene Philharmonic concert that ran from April 10th to May 1st (Classical IV and Classical V) during the 49th season. It includes information about the pieces performed, artists and musicians, and advertising from local companies.
Date:
April 1999
Creator:
Abilene Philharmonic
Object Type:
Pamphlet
System:
The Portal to Texas History
Calorimeter Preamplifier Hybrid Circuit Test Jig
There are two ways in which the testing may be initiated, remotely or locally. If the remote operation is desired, an external TTL level signal must be provided to the test jig with the remotellocal switch on the side of the test jig switched to remote. A logic high will initiate the test. A logic low will terminate the test. In the event that an external signal is connected to the test jig while local operation occurs, the local control takes precedence over remote control. Once a DVT has been locked in the ZIF socket and the DIP switches are selected, the Push-to-Test button may be depressed. Momentarily depressing the button will initiate a test with a minimum 400 ms duration. At the same time a PBCLOCK and PBLATCH pulses will be initiated and the power rails +12V, +8V, and -6V will be ramped to full voltage. The time at which the power rails reach the full voltage is about 13 ms and it is synchronized with bypass capacitors placed on COMP input of U20 and U22 and on the output of U23 voltage regulators. The voltage rails are supplied to a {+-}10% window comparator. A red LED indicates the …
Date:
April 19, 1999
Creator:
Abraham, Benjamin M.
Object Type:
Report
System:
The UNT Digital Library
Phase stability of laves intermetallics in stainless steel-zirconium alloys.
Phase transformations occurring in a stainless steel-15 wt% zirconium (SS-15Zr) alloy were studied by in situ neutron diffraction. Neutron diffraction patterns as a function of time were obtained on alloys that were held at various elevated temperatures (1084-1275 C). As-cast SS-15Zr alloys contain ferrite, austenite, ZrFe{sub 2}-type Laves polytypes C36 and C15, and small amounts of a Fe{sub 23}Zr{sub 6}-type intermetallic. Annealing at high temperatures resulted in an increase of the Fe{sub 23}Zr{sub 6}, intermetallic content. The C15 Laves polytype is the equilibrium phase for T {le} 1230 C; C36 is the stable polytype at higher temperatures ({approximately}1275 C). Phase changes were slow for temperatures <1100 C.These findings have important implications for use of the SS-15Zr alloy as a nuclear waste form.
Date:
April 8, 1999
Creator:
Abraham, D. P.
Object Type:
Article
System:
The UNT Digital Library
Field emission from carbon films deposited by VHF CVD on difference substrates
As previously demonstrated, non-diamond carbon (NDC) films deposited at low temperatures 200-300 C on silicon tips reduced the threshold of field emission. In this paper we will present the results of the study of field emission from flat NDC films prepared by VHF CVD. Emission measurements were performed in a diode configuration at approximately 10{sup {minus}10} Torr. NDC films were deposited on ceramic and on c-Si substrates sputter coated with layers of Ti, Cu, Ni and Pt. The back contact material influences the emission characteristics but not as a direct correlation to work function. A model of field emission from metal-NDC film structures will be discussed.
Date:
April 1, 1999
Creator:
Abramov, A A; Andronov, A N; Felter, T E; Ioffe, A F; Kosarev, A I; Shotov, M V et al.
Object Type:
Article
System:
The UNT Digital Library
U.S./Russian cooperative efforts to enhance nuclear MPC&A at VNIITF, (Chelyabinsk-70)
The work described here is part of an effort called the Nuclear Materials Protection, Control, and Accounting (MPC&A) Program, a cooperative program between the US Department of Eenrgy (DOE) and Russia's Ministry of Atomic Energy (MinAtom). The objective of the program is to reduce the risk of nuclear proliferation by strengthening MPC&A systems at Russian nuclear Facilities. This paper describes that portion of the MPC&A program that is directed specifically to the needs of the All Russian Scientific Research Institute of Technical Physics (VNIITF), also called Chelyabinsk-70. A major MPC&A milestone was met at VNIITF when the MPC&A improvements were commissioned at the Pulse Research Reactor Facility in May of this year.
Date:
April 20, 1999
Creator:
Abramson, B.; Apt, K.; Blasy, J.; Bukin, D.; Churikov, Y.; Curtis, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Kosovo and NATO: Selected Issues of International Law
None
Date:
April 28, 1999
Creator:
Ackerman, David M.
Object Type:
Report
System:
The UNT Digital Library
The Hybrid Emulsion Detector for MINOS R&D Proposal
The MINOS (Main Injector Neutrino Oscillation Search) experiment is designed to search for neutrino oscillations with a sensitivity significantly greater than has been achieved to date. The phenomenon of neutrino oscillations, whose existence has not been proven convincingly so far, allows neutrinos of one "flavor" (type) to slowly transform themselves into another flavor, and then back again to the original flavor, as they propagate through space or matter. The MINOS experiment is optimized to explore the region of neutrino oscillation "parameter space" suggested by previous investigations of atmospheric neutrinos: the Kamiokande, IMB, Super-Kamiokande and Soudan 2 experiments. The study of oscillations in this region with a neutrino beam from the Main Injector requires measurements of the beam after a very long flight path. This in turn requires an intense neutrino beam and a massive detector in order to have an adequate event rate at a great distance from the source. We propose to enhance significantly the physics capabilities of the MINOS experiment by the addition of a Hybrid Emulsion Detector at Soudan, capable of unambigous identification of the neutrino flavor. Recent developments in emulsion experiments make such a detector possible, although significant technological challenges must be overcome. We propose to …
Date:
April 1, 1999
Creator:
Adamson, P.; Alexandrov, K. V.; Allison, W. W.M.; Alner, G. J.; Ambats, I.; Anderson, B. et al.
Object Type:
Report
System:
The UNT Digital Library
Damage Accumulation in MgAl{sub 2}O{sub 4} and Yttria-Stabilized ZrO{sub 2} by Xe-Ion Irradiation
Magnesium-aluminate spinel (MAS) and yttria-stabilized zirconia (YSZ) are being considered for use as ceramic matrices in proliferation resistant fuels and radioactive storage systems, and may be used either as individual entities or as constituents in multicomponent ceramic systems. It is worthwhile, therefore, to compare radiation damage in these two potentially important materials when subjected to similar irradiation conditions, e.g., ion beam irradiation. To compare radiation damage properties of these two materials, single crystals of spinel and zirconia were irradiated with 340 keV Xe{sup ++} ions at 120 K, and subsequently investigated by Rutherford backscattering and ion channeling (RBS/C), and optical absorption spectroscopy. Results indicate that damage accumulation in both spinel and zirconia follow a three stage process: (1) very slow damage accumulation over a wide range of dose; (2) rapid changes in damage over a range of doses from about 0.25 to 25 displacements per atom (DPA); (3) slower damage accumulation at very high doses and possibly saturation. Optical absorption results indicate that F-centers form in Xe ion-irradiated spinel and that the concentration of these centers saturates at high dose. Absorption bands are also formed in both spinel and zirconia that are due to point defect complexes formed upon irradiation. …
Date:
April 25, 1999
Creator:
Afanasyev-Charkin, I.V.; Gritsyna, V.T.; Cooke, D.W.; Bennett, B.L. & Sickafus, K.E.
Object Type:
Article
System:
The UNT Digital Library
Development of Basic Housing Systems for Maximum Affordability
The ability to provide safe, habitable, comfortable housing for very low income residents within the target budget of $10,000 presents unique design and construction challenges. However, a number of preliminary conclusions have been inferred as being important concepts relative to the study of affordable housing. The term affordable housing can have many meanings and research is needed to define this explicitly. As it is most often used, affordable housing refers to an economic relationship between the price of housing, household income and current interest rates available from a lending institution. There is no direct relationship between architectural style, construction technology or user needs and the concept of affordability. For any home to be affordable, the home owner must balance the combination of housing needs and desires within the limits of an actual budget. There are many misconceptions that affordable housing must be defined as housing for those who cannot afford the free-market price. The concept of affordable housing must also include a component that recognizes the quality of the housing as an important element of the design and construction. In addition, responses to local climate impacts are necessary and are always part of a regional expression of architectural design. By …
Date:
April 19, 1999
Creator:
Aglan, H.; Gibbons, A.; McQueen, T. M.; Morris, C.; Raines, J. & Wendt, R. L.
Object Type:
Article
System:
The UNT Digital Library
Nuclear excitation by electronic transition (NEET).
We present a report on recent measurements using the Advanced Photon Source at Argonne National Laboratory to explore the phenomenon of Nuclear Excitation by Electronic Transition (NEET) in the {sup 189}Os atomic/nuclear system.
Date:
April 28, 1999
Creator:
Ahmad, I.; Dunford, R. W.; Esbensen, H.; Gemmell, D. S.; Kanter, E. P.; Kraessig, B. et al.
Object Type:
Article
System:
The UNT Digital Library
Characterizing Composition Modulations in InAs/AIAs Short-Period Superlattices
The formation of quantum wires has much interest due to their novel electronic properties which may lead to enhanced optoelectronic device performance and greater photovoltaic efficiencies. One method of forming these structures is through spontaneous lateral modulation found during the epitaxial growth of III/V alloys. In this paper, we report and summarize our investigations on the formation of lateral moduation in the MBE grown InAlAs/InP(001) system. This system was grown as a short-period superlattice where n-monolayers of InAs are deposited followed by m-Monolayers of AlAs (with n and m~2) and this sequence is repeated to grown a low strain InAlAs ternary alloy on InP(001) that exhibits lateral modulation. Films were grown under a variety of condition (growth temperature, effective alloy composition, superlattice period, and growth rate). These films have been extensively analyzed using X-ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM) and microcharacterization, in addition to photon-based spectroscopes. Here we present results of several microstructural characterizations using a wide range of TEM-based techniques, and compare them to results from the other methods to obtain a unified understanding of composition modulation. Two strong points consistently emerge: 1) The lateral modulation wavelength is insensitive to growth temperature and effective alloy …
Date:
April 26, 1999
Creator:
Ahrenkiel, S. P.; Follstaedt, D. M.; Jones, E. D.; Lee, S. R.; Mascarenhas, A.; Mirecki-Millunchick, J. et al.
Object Type:
Article
System:
The UNT Digital Library
MAGNETO-CHEMICAL CHARACTER STUDIES OF NOVEL FE CATALYSTS FOR COAL LIQUEFACTION
The primary objectives of research during this period were: (1) To prepare iron-cobalt-molybdenum trioxide catalysts using co-precipitation method; and (2) To examine the surface character of these catalysts with CO and Syngas as probe molecules by FTIR spectroscopy.
Date:
April 1, 1999
Creator:
Akundi, Murty A.
Object Type:
Report
System:
The UNT Digital Library
A Silicon, Carbon and Deuterium NMR Investigation of Molecular Templating in Amorphous Silicas
The precise pore sizes defined by crystalline zeolite lattices have led to intensive research on zeolite membranes. Unfortunately zeolites have proven to be extremely difficult to prepare in a defect-free thin film form needed for membrane flux and selectivity. We introduce tetrapropylammonium TPA (a structure directing agent for zeolite ZSM-5) into a silica sol and exploit the development of high solvation stresses to create templated amorphous silicas with pore apertures comparable in size to those of ZSM-5. {sup 29}Si and {sup 2}H NMR experiments were performed to evaluate the efficacy of our templating approach. The {sup 29}Si NMR spectrum of the silica matrix was observed by an intermolecular cross-polarization experiment between the {sup 1}H nuclei of TPA and the {sup 29}Si nuclei in the silica matrix. The efficiency of the cross-polarization interaction was used to investigate the degree to which the matrix formed a tight cage surrounding the template molecule. Normally prepared xerogel materials exhibited only weak interactions between the two sets of nuclei. Drying under reduced pressure, where solvation stresses are maximized, resulted in significantly increased interactions. Analogous materials were prepared using fully deuterated TPA. The {sup 2}H NMR wideline spectra consisted of a partially narrowed resonance, corresponding to …
Date:
April 8, 1999
Creator:
Alam, T. M.; Assink, R. A.; Brinker, C. J.; Click, C. A. & Naik, S. J.
Object Type:
Article
System:
The UNT Digital Library
[Photograph 2012.201.B0348.0008]
Photograph used for a story in the Daily Oklahoman newspaper. Caption: "Three generations of the family prepare kolaches as Jewell Novotny is joined by her daughter, Dorothy Kroos, center, and grand daughter, Bonnie Kroos, 17."
Date:
April 12, 1999
Creator:
Albright, Bob
Object Type:
Photograph
System:
The Gateway to Oklahoma History
PROOF OF PRINCIPAL TEST TO FEED AND METER GRANULAR COAL INTO 450 PSIG GAS PRESSURE
The objective of this project is to demonstrate proof of principal to feed and meter granular coal into 450 psig gas pressure for use with pressurized fluidized bed combustors. This report summarizes work undertaken in the first quarter of 1999 in support of that objective. Materials testers have been designed and built to assess properties relevant to performance in the Stamet pump. Testing has been carried out to evaluate these properties for materials to be pumped. A small scale pump has been modified and preliminary testing has been carried out to assess the effectiveness of the sealing and venting modifications, and the effect of outlet material sealing plug length on required HP and gas leakage. The sealing and venting modifications worked well, and measurements of gas leakage and power requirements were in line with predictions made from the measured materials properties and pump geometry. Changes to the large scale pump test rig to upgrade to the necessary 450 psig pressure rating have been defined and components ordered. The data from the materials and small scale pump testing is being used to define the necessary changes to the large scale SBIR test pump to reach the 450 psig target.
Date:
April 1, 1999
Creator:
Aldred, Derek L.
Object Type:
Report
System:
The UNT Digital Library
Intracavity Frequency Doubling of a Diode-Pumped, External Cavity, Surface Emitting Semiconductor Laser
The authors present a compact, robust, solid-state blue light (490 nm) source capable of greater than 5 mW of output in a TEM{sub 00} mode. This device is an optically pumped, vertical external-cavity surface-emitting laser (VECSEL) with an intracavity frequency doubling crystal.
Date:
April 22, 1999
Creator:
Alford, W. J.; Allerman, A. A.; Crawford, M. H. & Raymond, T. D.
Object Type:
Article
System:
The UNT Digital Library
Broadly Turnable Pump-Resonant Diode-Pumped CW PPLN OPO
We have observed low threshold operation of a broadly tunable (2.18-3.4 µm) pump-resonant cw periodically poled lithium niobate (PPLN) optical parametric oscillator (OPO). When pumped at 806 nm with 410 mW from a custom-built diode laser the OPO generated 20 mW of idler output at 3.3 µm.
Date:
April 29, 1999
Creator:
Alford, W.J.; Bowers, Mark S.; Raymond, T.D. & Seamans, J.F.
Object Type:
Article
System:
The UNT Digital Library
Ignition dynamics of high explosives
The laser ignition of the explosives HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, C{sub 4}H{sub 8}N{sub 8}O{sub 8}), {delta}-phase HMX, PBX 9501 (95% HMX, 2.5% Estane, 2.5% BDNPA/BDNPF), TATB (1,3,5-triamino-2,4,6-trinitrobenzene, C{sub 6}H{sub 6}N{sub 6}O{sub 6}), and PBX 9502 (95% TATB, 5% Kel-F) and aged PBX 9502 has been conducted with the intent to compare the relative sensitivities of those explosives and to investigate the effect of beam profile, binder addition, and porosity. It has been found that there was little difference between a gaussian beam and a top hat profile on the laser ignition of HMX. The authors observe that the addition of binder in the amounts present in PBX 9501 resulted in longer ignition delays than that of HMX. In contrast to HMX, the addition of binder to TATB in PBX 9502 shows no measurable effect. Porosity effects were considered by comparing the ignition of granular HMX and pressed HMX pellets. Porosity appears to increase ignition delay due to an increased effective absorption scale and increased convective heat loss. This porosity effect also resulted in longer ignition delays for {delta}-phase HMX than for {beta}-phase HMX. In order to simulate ignition in voids or cracks, the standard ignition experiment was modified to include a NaCl …
Date:
April 1, 1999
Creator:
Ali, A. N.; Son, S. F.; Sander, R. K.; Asay, B. W. & Brewster, M. Q.
Object Type:
Report
System:
The UNT Digital Library