States

Rayleigh-Taylor instability experiments in a cylindrically convergent geometry (open access)

Rayleigh-Taylor instability experiments in a cylindrically convergent geometry

Due to the sensitivity of Rayleigh-Taylor instabilities to initial conditions and due to the difficulty of forming well controlled cylindrical or spherical fluid interfaces, Rayleigh-Taylor experiments are often performed with simple, planar interfaces. Rayleigh-Taylor instability phenomena of practical interest, however, (e.g., underwater explosions, supernova core collapses, and inertial confinement fusion capsule implosions) are typically associated with cylindrical or spherical interfaces in which convergent flow effects have an important influence on the dynamics of instability growth. Recently, Meshkov et.al. have developed a novel technique for studying Rayleigh-Taylor instability growth in a cylindrically convergent geometry. Their experiments utilized low-strength gelatin rings which are imploded by a detonating gas mixture of oxygen and acetylene. Since the gelatin itself has sufficient strength to resist significant deformation by gravity, no membranes are needed to define the ring shape. This experimental technique is attractive because it offers a high degree of control over the interfacial geometry and over the material`s strength and rigidity, which can be varied by adjusting the gelatin concentration. Finally, since both the gelatin and the explosive product gases are transparent, optical diagnostics can be used.
Date: August 25, 1995
Creator: Goodwin, B. & Weir, S.
Object Type: Report
System: The UNT Digital Library
Choppertron II (open access)

Choppertron II

We present experimental results of a version of the Choppertron microwave generator designed to work with the high emittance beam of the Advanced Test Accelerator (ATA). Simulations showed that a 800-A, 120 {pi} cm-mrad beam (typical of ATA), could produce 800 MW of rf (11.4 GHz) power using two 12-cell, traveling-wave output structures. Funding contraints prevented final tuning of the modulator system and limited the experiment to 530 MW in narrow pulses. Over 400 MW were extracted from a single output structure through fundamental waveguide. Beam breakup was successfully suppressed with >800 amperes transported through the extraction section.
Date: April 25, 1995
Creator: Houck, T.L.; Westenskow, G.A.; Haimson, J. & Mecklenburg, B.
Object Type: Article
System: The UNT Digital Library
Monthly energy review, October 1995 (open access)

Monthly energy review, October 1995

This is the June report by the Energy Information Administration. The contents of the report include an energy overview, energy consumption, petroleum, natural gas, oil and gas resource development, coal, electricity, nuclear energy, energy prices, and international energy. Included are appendices containing thermal conversion factors, metric and other physical conversion factors, and carbon dioxide emission factors for coal.
Date: October 25, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Chemical kinetic modelling of hydrocarbon ignition (open access)

Chemical kinetic modelling of hydrocarbon ignition

Chemical kinetic modeling of hydrocarbon ignition is discussed with reference to a range of experimental configurations, including shock tubes, detonations, pulse combustors, static reactors, stirred reactors and internal combustion engines. Important conditions of temperature, pressure or other factors are examined to determine the main chemical reaction sequences responsible for chain branching and ignition, and kinetic factors which can alter the rate of ignition are identified. Hydrocarbon ignition usually involves complex interactions between physical and chemical factors, and it therefore is a suitable and often productive subject for computer simulations. In most of the studies to be discussed below, the focus of the attention is placed on the chemical features of the system. The other physical parts of each application are generally included in the form of initial or boundary conditions to the chemical kinetic parts of the problem, as appropriate for each type of application being addressed.
Date: August 25, 1995
Creator: Westbrook, C.K.; Pitz, W.J.; Curran, H.J.; Gaffuri, P. & Marinov, N.M.
Object Type: Article
System: The UNT Digital Library
Local positioning system (open access)

Local positioning system

Navigation systems have been vital to transportation ever since man took to the air and sea. Early navigation systems utilized the sextant to navigate by starlight as well as the magnetic needle compass. As electronics and communication technologies improved, inertial navigation systems were developed for use in ships and missile delivery. These systems consisted of electronic compasses, gyro-compasses, accelerometers, and various other sensors. Recently, systems such as LORAN and the Global Positioning System (GPS) have utilized the properties of radio wave propagation to triangulate position. The Local Positioning System (LPS), described in this paper, is an implementation of a limited inertial navigation system designed to be used on a bicycle. LPS displays a cyclist`s current position relative to a starting location. This information is displayed in Cartesian-like coordinates. To accomplish this, LPS relies upon two sensors, an electronic compass sensor and a distance sensor. The compass sensor provides directional information while the distance sensor provides the distance traveled. This information yields a distance vector for each point in time which when summed produces the cyclist`s current position. LPS is microprocessor controlled and is designed for a range of less than 90 miles.
Date: July 25, 1995
Creator: Kyker, R.
Object Type: Article
System: The UNT Digital Library
Advanced microinstrumentation for rapid DNA sequencing and large DNA fragment separation (open access)

Advanced microinstrumentation for rapid DNA sequencing and large DNA fragment separation

Our efforts to develop novel technology for a rapid DNA sequencer and large fragment analysis system based upon gel electrophoresis are described. We are using microfabrication technology to build dense arrays of high speed micro electrophoresis lanes that will ultimately increase the sequencing rate of DNA by at least 100 times the rate of current sequencers. We have demonstrated high resolution DNA fragment separation needed for sequencing in polyacrylamide microgels formed in glass microchannels. We have built prototype arrays of microchannels having up to 48 channels. Significant progress has also been made in developing a sensitive fluorescence detection system based upon a confocal microscope design that will enable the diagnostics and detection of DNA fragments in ultrathin microchannel gels. Development of a rapid DNA sequencer and fragment analysis system will have a major impact on future DNA instrumentation used in clinical, molecular and forensic analysis of DNA fragments.
Date: January 25, 1995
Creator: Balch, J.; Davidson, J.; Brewer, L.; Gingrich, J.; Koo, J.; Mariella, R. et al.
Object Type: Report
System: The UNT Digital Library
The statistical efficiency of filtered backprojection in emission tomography (open access)

The statistical efficiency of filtered backprojection in emission tomography

While there has been much interest in developing tomographic reconstruction algorithms that are more statistically efficient than filtered backprojection (FB), the degree of improvement possible has not been well understood. We present an algorithm-independent theory of statistical accuracy attainable in emission tomography that provides a geometrical interpretation of the statistical efficiency of FB. Our analysis shows that, in general, one can build unbiased estimators with smaller variance than FB. The improvement in performance is obtained by exploiting the range properties of the Radon transform.
Date: September 25, 1995
Creator: Kuruc, A.
Object Type: Report
System: The UNT Digital Library
Public/private key certification authority and key distribution. Draft (open access)

Public/private key certification authority and key distribution. Draft

Traditional encryption, which protects messages from prying eyes, has been used for many decades. The present concepts of encryption are built from that heritage. Utilization of modern software-based encryption techniques implies much more than simply converting files to an unreadable form. Ubiquitous use of computers and advances in encryption technology coupled with the use of wide-area networking completely changed the reasons for utilizing encryption technology. The technology demands a new and extensive infrastructure to support these functions. Full understanding of these functions, their utility and value, and the need for an infrastructure, takes extensive exposure to the new paradigm. This paper addresses issues surrounding the establishment and operation of a key management system (i.e., certification authority) that is essential to the successful implementation and wide-spread use of encryption.
Date: September 25, 1995
Creator: Long, J.P.; Christensen, M.J.; Sturtevant, A.P. & Johnston, W.E.
Object Type: Article
System: The UNT Digital Library
Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane. Quarterly technical progress report 8, January--March, 1995 (open access)

Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane. Quarterly technical progress report 8, January--March, 1995

Activities during this quarter focused on fine tuning of catalyst characterization and synthesis techniques. Improvements in catalyst activity test methods were also implemented but more remains to be done. Specific accomplishments include: improved characterization of vanadyl pyrophosphate (VPO) and Si promoted VPO by FTIR and FTIR of chemisorbed bases; several minor improvements in catalyst preparation technique resulting in enhanced catalyst yield, better control of catalyst composition, and generation of less waste; preliminary pulsed reaction data on methane oxidation were also acquired. Preliminary activity measurements for methane conversion (without oxygen) in a pulsed reactor over VPO indicate that the primary reaction product is CO. Carbon dioxide is also formed but selectivity to CO{sub 2} decreases with number of pulses. These results suggest that selectivity to partially oxidized products improves with catalyst reduction and suggest that some surface modification will be required to obtain oxidized hydrocarbon products. Note that catalyst activation (conversion from the precursor to VPO) has been carried out using air. For butane oxidation catalysts VPO is activated in a 1% butane/air mixture which produces a slightly reduced catalyst.
Date: May 25, 1995
Creator: McCormick, R.L.
Object Type: Report
System: The UNT Digital Library
Localized weld metal corrosion in stainless steel water tanks (open access)

Localized weld metal corrosion in stainless steel water tanks

The rapidly developed leaks within the TFC and TFD tanks (LLNL groundwater treatment facilities) were caused by localized corrosion within the resolidified weld metal. The corrosion was initiated by the severe oxidation of the backsides of the welds which left the exposed surfaces in a condition highly susceptible to aqueous corrosion. The propagation of surface corrosion through the thickness of the welds occurred by localized corrosive attack. This localized attack was promoted by the presence of shielded aqueous environments provided by crevices at the root of the partial penetration welds. In addition to rapid corrosion of oxidized surfaces, calcium carbonate precipitation provided an additional source of physical shielding from the bulk tank environment. Qualification testing of alternate weld procedures showed that corrosion damage can be prevented in 304L stainless steel GTA welds by welding from both sides while preventing oxidation of the tank interior through the use of an inert backing gas such as argon. Corrosion resistance was also satisfactory in GMA welds in which oxidized surfaces were postweld cleaned by wire brushing and chemically passivated in nitric acid. Further improvements in corrosion resistance are expected from a Mo-containing grade of stainless steel such as type 316L, although test results …
Date: May 25, 1995
Creator: Strum, M.J.
Object Type: Report
System: The UNT Digital Library
Transport of a Partially-Neutralized Ion Beam in a Heavy-Ion Fusion Reactor Chamber (open access)

Transport of a Partially-Neutralized Ion Beam in a Heavy-Ion Fusion Reactor Chamber

In a heavy-ion driven, inertial confinement fusion power plant, a space-charge dominated beam of heavy ions must be transported through a reactor chamber and focused on a 2-3 mm spot at the target. The spot size at the target is determined by the beam emittance and space charge, plus chromatic aberrations in the focusing lens system and errors in aiming the beam. The gain of the ICF capsule depends on the focal spot size. We are investigating low density, nearly-ballistic transport using an electromagnetic, r-z particle-in-cell code. Even at low density (n {approx} 5 {times} 10{sup 13} cm{sup {minus}3}), beam stripping may be important. To offset the effects of stripping and reduce the space charge, the beam is partially charge neutralized via a pre-formed plasma near the chamber entrance. Additional electrons for charge neutralization come from ionization of the background gas by the beam. Simulations have shown that stripping can greatly increase the spot size; however, partial neutralization can offset most of this increase.
Date: April 25, 1995
Creator: Callahan, D. A. & Langdon, A. B.
Object Type: Article
System: The UNT Digital Library
International petroleum statistics report, August 1995 (open access)

International petroleum statistics report, August 1995

The International Petroleum Statistics Report presents data on international oil production, demand, imports, exports, and stocks. The report has four sections. Section 1 contains time series data on world oil production, and on oil demand and stocks in the Organization for Economic Cooperation and Development (OECD). This section contains annual data beginning in 1985, and monthly data for the most recent two years. Section 2 presents an oil supply/demand balance for the world. This balance is presented in quarterly intervals for the most recent two years. Section 3 presents data on oil imports by OECD countries. This section contains annual data for the most recent year, quarterly data for the most recent two quarters, and monthly data for the most recent twelve months. Section 4 presents annual time series data on world oil production and oil stocks, demand, and trade in OECD countries. World oil production and OECD demand data are for the years 1970 through 1994; OECD stocks from 1973 through 1994; and OECD trade from 1984 through 1994.
Date: August 25, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library
The effect of chemical composition on the PCT durability of mixed waste glasses from wastewater treatment sludges (open access)

The effect of chemical composition on the PCT durability of mixed waste glasses from wastewater treatment sludges

An experimental program has been designed to examine the chemical durability of glass compositions derived from the vitrification of simulated wastewater treatment sludges. These sludges represent the majority of low-level mixed wastes currently in need of treatment by the US DOE. The major oxides in these model glasses included SiO{sub 2}, Al{sub 2}O{sub 3}, B{sub 2}O{sub 3}, Na{sub 2}O, CaO and Fe{sub 2}O{sub 3}. In addition, three minor oxides, BaO, NiO, and PbO, were added as hazardous metals. The major oxides were each varied at two levels resulting in 32 experimental glasses. The chemical durability was measured by the 7-Day Product Consistency Test (PCT). The normalized sodium release rates (NRR{sub Na}) of these glasses ranged from 0.01 to 4.99 g/m{sup 2}. The molar ratio of the glass-former to glass-modifier (F/M) was found to have the greatest effect on PCT durability. Glass-formers included SiO{sub 2}, Al{sub 2}O{sub 3}, and B{sub 2}O{sub 3}, while Na{sub 2}O, CaO, BaO, NiO, and PbO were glass-modifiers. As this ratio increased from 0.75 to 2.0, NRR{sub Na} was found to decrease between one and two orders of magnitude. Another important effect on NRR{sub Na} was the Na{sub 2}O/CaO ratio. As this ratio increased from 0.5 to …
Date: January 25, 1995
Creator: Resce, James L.; Ragsdale, R. Giles; Overcamp, Thomas J.; Bickford, Dennis F. & Cicero, Connie A.
Object Type: Article
System: The UNT Digital Library
CENRTC Project {number_sign}2F3EOA, OCB A-376, acceptance test procedure (open access)

CENRTC Project {number_sign}2F3EOA, OCB A-376, acceptance test procedure

This test procedure provides the steps necessary to verify correct functional operation of controls, annunciators, alarms, protective relays and related systems impacted by CENRTC {number_sign}2F3E0A, Microwave Transfer Trip Project, modification work performed under work package 6B-93-00041/M. This procedure separates three tests into separate sections: energization of A-376 duplex panel and circuits; SCADA tests; and A-376 local trip tests.
Date: January 25, 1995
Creator: Akerson, A. W.
Object Type: Report
System: The UNT Digital Library
Tank 241-TX-105 headspace gas and vapor characterization results for samples collected in December 1995 (open access)

Tank 241-TX-105 headspace gas and vapor characterization results for samples collected in December 1995

Significant changes have been made to all of the original vapor characterization reports. This report documents specific headspace gas and vapor characterization results for all vapor sampling events to date. In addition, changes have been made to the original vapor reports to qualify the data based on quality assurance issues associated with the performing laboratories
Date: September 25, 1995
Creator: Huckaby, J.L. & Bratzel, D.R.
Object Type: Report
System: The UNT Digital Library
Managing in an environmentally constrained world (open access)

Managing in an environmentally constrained world

In thinking about this issue, one comes to fundamental question: Why are we concerned at all? Why have all of us gathered here, rather than simply continue to clean up what we should from the past and control our emissions for the present and the future? The answer, I think, may be hinted at by several scenarios (which, although plausible given current trends, are intended to be hypothetical).
Date: September 25, 1995
Creator: Allenby, B.R.
Object Type: Article
System: The UNT Digital Library
Thermogravimetric analysis studies (open access)

Thermogravimetric analysis studies

Independent of thermal loading scenarios, the waste packages at the proposed repository at Yucca Mountain, Nevada will be exposed to environmental conditions of temperatures below 100 C with a range of possible relative humidities. Under high relative humidities, the formation of thin water films on the metal surfaces will occur. Previous work at ambient conditions has shown that on susceptible metals, the water-film-covered metal has an enhanced corrosion rate relative to the dry oxidation of the metal. The transition relative humidity where oxidation changes from dry oxidation to aqueous electrochemical corrosion is called the critical relative humidity. Determination of this transition is important in estimating the performance of the candidate materials (especially corrosion allowance materials), because of the marked increase in degradation rate above the critical relative humidity, typically 10-10{sup 2} times This activity is concerned with short term measurements of corrosion and oxidation rates using a high sensitivity microbalance. The experimental work will determine the critical humidity level for candidate metals under a variety of conditions. From the literature, the critical humidity level typically are around 70% relative humidity, but this level is affected by the metal, gas composition, temperature, and the presence of contaminants on the surface, particularly …
Date: August 25, 1995
Creator: Gdowski, G.
Object Type: Report
System: The UNT Digital Library
Slag characterization and removal using pulse detonation for coal gasification. Quarterly research report, October--December, 1995 (open access)

Slag characterization and removal using pulse detonation for coal gasification. Quarterly research report, October--December, 1995

Experiments will mainly focus on breaking the bonds within the slag itself using detonation wave. For the experiments, initial suggestion was to build up slag deposit around a representative tube by placing it inside the convection pass of an actual boiler at the Northern States Power Company. But it was later concluded that once the tube is cooled to room condition, the thermal stress will greatly reduce the bonding between the heat transfer surface and the slag. It was concluded that the slag will be attached to the tube using high density epoxy resin. High density epoxy will be used so that they do not diffuse into the slag and strengthen the bonding within the slag. Suggestions on candidate epoxy are provided by MTI lab. MTI also provided PVAMU with different kinds of slags for testing. The deposits for characterization were from a subbituminous coal fired utility boiler.
Date: December 25, 1995
Creator: Huque, Z.; Zhou, J.; Mei, D. & Biney, P.O.
Object Type: Report
System: The UNT Digital Library
Development of a data management system for assistance in conducting Area of Reviews (AORs) on Class II injection wells in Oklahoma. Quarterly report, July--September, 1995 (open access)

Development of a data management system for assistance in conducting Area of Reviews (AORs) on Class II injection wells in Oklahoma. Quarterly report, July--September, 1995

Project objectives are to provide the resources and capabilities to permit the State of Oklahoma to conduct Area of Review (AOR) variance analysis on a statewide level including: (1) the analysis and identification of areas which may qualify for AOR variances; (2) the correlation of information from various databases and automation systems to conduct AORs in areas that do not qualify for variances; (3) the evaluation of the risk of pollution, during permitting and monitoring, using risk based data analysis; and (4) the ability to conduct spatial analysis of injection well data in conjunction with other geographically referenced information. The division successfully converted its mainframe computer surety system to the new client server network and implemented it on September 29, 1995. The division currently lacks sufficient storage space to bring the existing oil and gas spatially referenced data systems in-house and fully integrate the systems for use in the determination of AORs or AOR variances. The second installment of the awarded grant allows for the purchase of the developmental server that will provide the minimum computer storage space to convert the remainder of the mainframe computer systems.
Date: October 25, 1995
Creator: Schmidt, M.W.
Object Type: Report
System: The UNT Digital Library
Maintenance of the coal sample bank and database. Quarterly technical progress report, January 1, 1995--March 31, 1995 (open access)

Maintenance of the coal sample bank and database. Quarterly technical progress report, January 1, 1995--March 31, 1995

This project is concerned with the development of a coal database providing information to the public and private research sectors on 30 coal samples. The information from these samples, along with information previously collected on 26 samples, will be distributed to DOE contractors performing coal research.
Date: August 25, 1995
Creator: Davis, A. & Glick, D. C.
Object Type: Report
System: The UNT Digital Library
Vapor and gas sampling of single-shell tank 241-BY-108 using the vapor sampling system (open access)

Vapor and gas sampling of single-shell tank 241-BY-108 using the vapor sampling system

This document presents sampling data resulting from the October 27, 1994, sampling of SST 241-BY-108 using the vapor sampling system.
Date: September 25, 1995
Creator: Caprio, G.S.
Object Type: Report
System: The UNT Digital Library
Microbial activity at Yucca Mountain (open access)

Microbial activity at Yucca Mountain

The U.S. Department of Energy is engaged in a suitability study for a potential geological repository at Yucca Mountain, Nevada, for the containment and storage of commercially generated spent fuel and defense high-level nuclear waste. There is growing recognition of the role that biotic factors could play in this repository, either directly through microbially induced corrosion (MIC), or indirectly by altering the chemical environment or contributing to the transport of radionuclides. As a first step toward describing and predicting these processes, a workshop was held on April 10-12, 1995, in Lafayette, California. The immediate aims of the workshop were: (1) To identify microbially related processes relevant to the design of a radioactive waste repository under conditions similar to those at Yucca Mountain. (2) To determine parameters that are critical to the evaluation of a disturbed subterranean environment. (3) To define the most effective means of investigating the factors thus identified.
Date: September 25, 1995
Creator: Horn, J.M. & Meike, A.
Object Type: Report
System: The UNT Digital Library
Vapor and gas sampling of single-shell tank 241-BX-104 using the vapor sampling system (open access)

Vapor and gas sampling of single-shell tank 241-BX-104 using the vapor sampling system

This document presents sampling data resulting from the December 30, 1994, sampling of SST 241-BX-104 using the vapor sampling system.
Date: September 25, 1995
Creator: Caprio, G.S.
Object Type: Report
System: The UNT Digital Library
ISOSHLD Analysis for storing transuranic ion exchange columns (open access)

ISOSHLD Analysis for storing transuranic ion exchange columns

The objective of the ISOSHLD Analysis is to estimate the thickness of concrete shielding necessary to store the KE Fuel Storage Basin transuranic ion exchange columns above ground. The quantity of radioactive material was taken from the tables in PNL-IX-IR-0004, ``Best Estimate of Radionuclide Inventories by Canister.`` The cesium activity was based on a mass balance. The exposure rate (R/hr) was slightly higher in the resulting ISOSHLD model than actually measured due to possible measurement errors and conservative assumptions in the computer model
Date: September 25, 1995
Creator: Mills, W.C.
Object Type: Report
System: The UNT Digital Library