185 Matching Results

Results open in a new window/tab.

3-D Finite Element Analysis of Induction Logging in a Dipping Formation (open access)

3-D Finite Element Analysis of Induction Logging in a Dipping Formation

Electromagnetic induction by a magnetic dipole located above a dipping interface is of relevance to the petroleum well-logging industry. The problem is fully three-dimensional (3-D) when formulated as above, but reduces to an analytically tractable one-dimensional (1-D) problem when cast as a small tilted coil above a horizontal interface. The two problems are related by a simple coordinate rotation. An examination of the induced eddy currents and the electric charge accumulation at the interface help to explain the inductive and polarization effects commonly observed in induction logs from dipping geological formations. The equivalence between the 1-D and 3-D formulations of the problem enables the validation of a previously published finite element solver for 3-D controlled-source electromagnetic induction.
Date: July 20, 2000
Creator: Everett, Mark E.; Badea, Eugene A,; Shen, Liang, C.; Merchant, Gulamabbas A. & Weiss, Chester J.
System: The UNT Digital Library
3 V manganese oxide electrode materials for lithium batteries. (open access)

3 V manganese oxide electrode materials for lithium batteries.

None
Date: June 20, 2000
Creator: Johnson, C. S. & Thackeray, M. M.
System: The UNT Digital Library
3D HYDRA Simulations of NIF Targets (open access)

3D HYDRA Simulations of NIF Targets

The performance of NIF target designs is simulated in three dimensions using the HYDRA multiphysics radiation hydrodynamics code. In simulations of a cylindrical NIF hohlraum that include an imploding capsule, the motion of the wall material inside the hohlraum shows a high degree of axisymmetry. Laser radiation is able to propagate through the entrance hole for the required duration of the pulse. Gross hohlraum energetics in the simulation mirror the results from an axisymmetric simulation. A simulation of a copper-doped beryllium ablator NIF capsule carried out over large solid angle resolved the full spectrum of the most dangerous modes that grow from surface roughness. Hydrodynamic instabilities evolve into the weakly nonlinear regime. There is no evidence of low mode jetting driven by nonlinear mode coupling.
Date: October 20, 2000
Creator: Marinak, M. M.; Kerbel, G. D.; Gentile, N. A.; Jones, O.; Pollaine, S.; Dittrich, T. R. et al.
System: The UNT Digital Library
The 3rd Dimension of Planetary Exploration - Deep Subsurface Sampling (open access)

The 3rd Dimension of Planetary Exploration - Deep Subsurface Sampling

None
Date: September 20, 2000
Creator: Blacic, James D.; Dreesen, Donald S. & Mockler, Theodore T.
System: The UNT Digital Library
Ab-Initio Step- and Kink-Formation Energies on Pb(111) (open access)

Ab-Initio Step- and Kink-Formation Energies on Pb(111)

Ab-initio formation energies for (100)- and (111)-microfacet steps on Pb(111) are in satisfactory agreement with measured values, given that these values are known only as well as the Pb(111) surface energy; the calculated step-energy ratio, 1.29, is within {approximately}8% of experiment. In contrast, calculated kink-formation energies, 41 and 60 meV for the two step types, are 40--50% below published experimental values derived from STM images. The discrepancy results from interpreting the images with a step-stiffness vs. kink-energy relation appropriate to (100) but not (111) surfaces. Good agreement is found when the step-stiffness data are reinterpreted, taking proper account of the trigonal symmetry of Pb(111).
Date: July 20, 2000
Creator: Feibelman, Peter J.
System: The UNT Digital Library
Abstraction of Thermal Hydrology and Coupled Processes for TSPA (open access)

Abstraction of Thermal Hydrology and Coupled Processes for TSPA

The thermal-hydrologic (TH) and coupled process models describe the evolution of a potential geologic repository as heat is released from emplaced waste. The evolution (thermal, hydrologic, chemical, and mechanical) of the engineered barrier and geologic systems is heavily dependent on the heat released by the waste packages and how the heat is transferred from the emplaced wastes through the drifts and through the repository host rock. The essential elements of this process are extracted (or abstracted) from the process-level models that incorporate the basic energy and mass conservation principles and applied to the total system models used to describe the overall performance of the potential repository. The process of total system performance assessment (TSPA) abstraction is the following. First is a description of the parameter inputs used in the process-level models. A brief description is given hereof past inputs for the viability assessment (e.g., for TSPA-VA) and current inputs for the site recommendation (TSPA-SR). This is followed by a highlight of the process-level models from which the abstractions are made. These include descriptions of TH, thermal-hydrologic-chemical (THC), and thermal-mechanical (TM) processes used to describe the performance of individual waste packages and waste emplacement drifts as well as the repository as …
Date: October 20, 2000
Creator: ITAMURA,MICHAEL T. & FRANCIS JR.,NICHOLAS D.
System: The UNT Digital Library
Accelerated Closure of the Hanford Site (open access)

Accelerated Closure of the Hanford Site

Cleanup of the Hanford Site is currently planned to take until 2046 and another approximately $SOB. In the summer of 1999, Fluor Hanford initiated an ''Accelerated Closure Team'' to evaluate opportunities to reduce this long schedule and high cost for the parts of the Hanford Site which they manage. To-date, this breakthrough team has developed two approaches which will move > 50 million curies away from the Columbia River sooner than planned and at a significantly reduced cost. The approaches successfully applied so far are presently being applied to other opportunities at Hanford.
Date: September 20, 2000
Creator: WILDE, R.T.
System: The UNT Digital Library
Adsorption of Barium (II) on Montmorillonite Surface (open access)

Adsorption of Barium (II) on Montmorillonite Surface

None
Date: July 20, 2000
Creator: Zhang, Pengchu; Brady, Patrick V.; Arthur, Sara E.; Zhou, Wei-Qing; Sawyer, Dale & Hesterberg, Dean A.
System: The UNT Digital Library
APPLICATION OF CERAMICS TO HIGH PRESSURE FUEL SYSTEMS (open access)

APPLICATION OF CERAMICS TO HIGH PRESSURE FUEL SYSTEMS

Diesel fuel systems are facing increased demands as engines with reduced emissions are developed. Injection pressures have increased to provide finer atomization of fuel for more efficient combustion, Figure 1. This increases the mechanical loads on the system and requires tighter clearances between plungers and bores to prevent leakage. At the same time, fuel lubricity has decreased as a byproduct of reducing the sulfur levels in fuel. Contamination of fuel by water and debris is an ever-present problem. For oil-lubricated fuel system components, increased soot loading in the oil results in increased wear rates. Additionally, engine manufacturers are lengthening warranty periods for engines and systems. This combination of factors requires the development of new materials to counteract the harsher tribological environment.
Date: August 20, 2000
Creator: Mandler, Jr., William F.
System: The UNT Digital Library
Application of Johnson Matthey CRT{trademark} Particle Filter System for Retrofit Emission Control of Heavy-Duty diesel Engines (open access)
ARB's Heavy-Duty Vehicle Smoke Inspection Program (open access)

ARB's Heavy-Duty Vehicle Smoke Inspection Program

None
Date: August 20, 2000
Creator: Jacobs, Paul E.
System: The UNT Digital Library
Battery charging in float vs. cycling environments (open access)

Battery charging in float vs. cycling environments

In lead-acid battery systems, cycling systems are often managed using float management strategies. There are many differences in battery management strategies for a float environment and battery management strategies for a cycling environment. To complicate matters further, in many cycling environments, such as off-grid domestic power systems, there is usually not an available charging source capable of efficiently equalizing a lead-acid battery let alone bring it to a full state of charge. Typically, rules for battery management which have worked quite well in a floating environment have been routinely applied to cycling batteries without full appreciation of what the cycling battery really needs to reach a full state of charge and to maintain a high state of health. For example, charge target voltages for batteries that are regularly deep cycled in off-grid power sources are the same as voltages applied to stand-by systems following a discharge event. In other charging operations equalization charge requirements are frequently ignored or incorrectly applied in cycled systems which frequently leads to premature capacity loss. The cause of this serious problem: the application of float battery management strategies to cycling battery systems. This paper describes the outcomes to be expected when managing cycling batteries with …
Date: April 20, 2000
Creator: COREY,GARTH P.
System: The UNT Digital Library
Bifurcation Mode of Relativistic and Charge-Displacement Self-Channeling (open access)

Bifurcation Mode of Relativistic and Charge-Displacement Self-Channeling

Stable self-channeling of ultra-powerful (P{sub 0} - 1 TW -1 PW) laser pulses in dense plasmas is a key process for many applications requiring the controlled compression of power at high levels. Theoretical computations predict that the transition zone between the stable and highly unstable regimes of relativistic/charge-displacement self-channeling is well characterized by a form of weakly unstable behavior that involves bifurcation of the propagating energy into two powerful channels. Recent observations of channel instability with femtosecond 248 nm pulses reveal a mode of bifurcation that corresponds well to these theoretical predictions. It is further experimentally shown that the use of a suitable longitudinal gradient in the plasma density can eliminate this unstable behavior and restore the efficient formation of stable channels.
Date: July 20, 2000
Creator: Borisov, A. B.; Cameron, Stewart M.; Luk, Ting S.; Nelson, Thomas R.; Van Tassle, A. J.; Santoro, J. et al.
System: The UNT Digital Library
Bistable Output from a Coupled-Resonator Vertical-Cavity Laser Diode (open access)

Bistable Output from a Coupled-Resonator Vertical-Cavity Laser Diode

The authors report a monolithic coupled-resonator vertical-cavity laser with an ion-implanted top cavity and a selectively oxidized bottom cavity which exhibits bistable behavior in the light output versus injection current. Large bistability regions over current ranges as wide as 18 mA have been observed with on/off contrast ratios of greater than 20 dB. The position and width of the bistability region can be varied by changing the bias to the top cavity. Switching between on and off states can be accomplished with changes as small as 250 {micro}W to the electrical power applied to the top cavity. Theoretical analysis suggests that the bistable behavior is the response of the nonlinear susceptibility in the top cavity to the changes in the bottom intracavity laser intensity as the bottom cavity reaches the thermal rollover point.
Date: July 20, 2000
Creator: Fischer, Arthur J.; Choquette, Kent D.; Chow, Weng W.; Allerman, Andrew A. & Geib, Kent M.
System: The UNT Digital Library
CAN FREE ELECTRON LASERS ANSWER CRITICAL QUESTIONS IN ULTRAVIOLET PHOTOBIOLOGY? (open access)

CAN FREE ELECTRON LASERS ANSWER CRITICAL QUESTIONS IN ULTRAVIOLET PHOTOBIOLOGY?

None
Date: January 20, 2000
Creator: SUTHERLAND,J.C.
System: The UNT Digital Library
CDF: Run II Physics Projections (open access)

CDF: Run II Physics Projections

In March 2001, the Fermilab Tevatron will start a new physics run of p{bar p} collisions at {radical}s = 2.0 TeV. The CDF experiments will collect a data sample of 2 fb{sup {minus}1} in the first two years. In this paper the authors describe the B physics prospects at CDF during the upcoming run.
Date: December 20, 2000
Creator: Tanaka, Maashi
System: The UNT Digital Library
The Ceryx QuadCAT Converter for Retrofit Applications (open access)

The Ceryx QuadCAT Converter for Retrofit Applications

None
Date: August 20, 2000
Creator: Edgar, Bradley L.
System: The UNT Digital Library
Characterization of Exhaust Emission Particulate Matter by Transmission Electron Microscopy (open access)

Characterization of Exhaust Emission Particulate Matter by Transmission Electron Microscopy

Health effects of PM are of intense interest TEM characterization well suited to provide information on individual particles--morphology--Elemental composition--Crystal structure Comparisons between spark ignition PM and diesel PM
Date: August 20, 2000
Creator: Blom, Douglas A.
System: The UNT Digital Library
Characterization of Heat Recovery Wheels in Thermally Regenerated Desiccant Systems Utilizing Evaporative Cooling (open access)

Characterization of Heat Recovery Wheels in Thermally Regenerated Desiccant Systems Utilizing Evaporative Cooling

None
Date: August 20, 2000
Creator: Sand, J. R.; Jalalzadeh-Azar, A. A. & Vineyard, E. A.
System: The UNT Digital Library
Characterization of high-voltage cathodes in CsBr-LiBr-KBr eutectic electrolyte (open access)

Characterization of high-voltage cathodes in CsBr-LiBr-KBr eutectic electrolyte

The transition-metal oxides LiMn{sub 2}O{sub 4}, MnO{sub 2}, CrO{sub 2}, and LiCoO{sub 2} were evaluated for possible use as high-voltage cathodes for potential geothermal power applications. These were coupled with Li(Si) anodes and a low-melting CsBr-LiBr-KBr eutectic electrolyte that melts at 228.5 C. Single-cell tests at 250 C and 300 C at 15.8 and 31.6 mA/cm{sup 2} showed that MnO{sub 2} performed the best overall and had the lowest polarization. A 5-cell battery test using LiMn{sub 2}O{sub 4} cathodes was only modestly successful due to possible parasitic chemical reactions between the cathode and electrolyte at the much higher temperature (500 C) during discharge. The overall energy densities for these cathode were still less than for FeS{sub 2}.
Date: April 20, 2000
Creator: GUIDOTTI,RONALD A. & REINHARDT,FREDERICK W.
System: The UNT Digital Library
Characterization of oxidation products on a ZrFe{sub 2}-type laves intermetallic exposed to 200{degree}C steam. (open access)

Characterization of oxidation products on a ZrFe{sub 2}-type laves intermetallic exposed to 200{degree}C steam.

The release of radioactive elements from the stainless steel-15 wt% zirconium (SS-15Zr) metal waste form will be governed by the corrosion behavior of ZrFe{sub 2}-type intermetallics phases present in the alloy. In this article, oxidation products that formed on a ZrFe{sub 2}-type intermetallic sample exposed to 200 C steam were characterized by Auger Electron Spectroscopy (AES) and Transmission Electron Microscopy (TEM). The data revealed two oxide layers on the sample surface: an outer crystalline iron-oxide layer and an inner amorphous zirconium-rich layer believed to be zirconium oxide. Thermodynamic considerations indicate that the zirconium-rich layer formed first. The iron-oxide layer appears to have resulted from the diffusion of iron through the zirconium-rich layer to the oxide-vapor interface.
Date: November 20, 2000
Creator: Abraham, D. P.; Dietz, N. & Finnegan, N.
System: The UNT Digital Library
Characterization of the Coherent Noise, Electromagnetic Compatibility and Electromagnetic Interference of the Atlas Em Calorimeter Front End Board (open access)

Characterization of the Coherent Noise, Electromagnetic Compatibility and Electromagnetic Interference of the Atlas Em Calorimeter Front End Board

The ATLAS Electromagnetic (EM) calorimeter (EMCAL) Front End Board (FEB) will be located in custom-designed enclosures solidly connected to the feedtroughs. It is a complex mixed signal board which includes the preamplifier, shaper, switched capacitor array analog memory unit (SCA), analog to digital conversion, serialization of the data and related control logic. It will be described in detail elsewhere in these proceedings. The electromagnetic interference (either pick-up from the on board digital activity, from power supply ripple or from external sources) which affects coherently large groups of channels (coherent noise) is of particular concern in calorimetry and it has been studied in detail.
Date: September 20, 2000
Creator: Chase, R. L.; Citterio, M.; Lanni, F.; Makowiecki, D.; Radeka, V.; Rescia, S. et al.
System: The UNT Digital Library
Charmed meson and onium production at the Tevatron (open access)

Charmed meson and onium production at the Tevatron

The authors report recent results of D*{sup {+-}} meson, J/{psi} and {Upsilon} production at the Fermilab Tevatron. They observe about 8,000 D*{sup {+-}} mesons reconstructed in the decay chain of D* {r_arrow} D{sub {pi}}{sup 0}, D{sup 0} {r_arrow} K{mu}+X. They measure the integrated D*{sup +} production cross section to be 347 {+-} 65(stat.) {+-} 58(sys.) nb for the rapidity range {vert_bar}{eta}(D*{sup +}){vert_bar} < 1.0 and the transverse momentum range p{sub T} (D*{sup +}) > 10 GeV/c. The measurement is slightly higher than the theoretical prediction, especially at lower pT range. We also measure the polarization of J/{psi} at production and find that the measured transverse polarization is not well explained by the color-octet model proposed to explain the anomalously high J/{psi} production cross section. We also present a new result on {Upsilon} production and polarization. Production of the {Upsilon} is consistent with being unpolarized.
Date: December 20, 2000
Creator: Nakaya, T.
System: The UNT Digital Library
Chemometric Analysis of Nuclear Magnetic Resonance Spectroscopy Data (open access)

Chemometric Analysis of Nuclear Magnetic Resonance Spectroscopy Data

Chemometric analysis of nuclear magnetic resonance (NMR) spectroscopy has increased dramatically in recent years. A variety of different chemometric techniques have been applied to a wide range of problems in food, agricultural, medical, process and industrial systems. This article gives a brief review of chemometric analysis of NMR spectral data, including a summary of the types of mixtures and experiments analyzed with chemometric techniques. Common experimental problems encountered during the chemometric analysis of NMR data are also discussed.
Date: July 20, 2000
Creator: ALAM,TODD M. & ALAM,M. KATHLEEN
System: The UNT Digital Library