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HCCI Combustion: Analysis and Experiments
Homogeneous charge compression ignition (HCCI) is a new combustion technology that may develop as an alternative to diesel engines with high efficiency and low NOx and particulate matter emissions. This paper describes the HCCI research activities being currently pursued at Lawrence Livermore National Laboratory and at the University of California Berkeley. Current activities include analysis as well as experimental work. On analysis, we have developed two powerful tools: a single zone model and a multi-zone model. The single zone model has proven very successful in predicting start of combustion and providing reasonable estimates for peak cylinder pressure, indicated efficiency and NOX emissions. This model is being applied to develop detailed engine performance maps and control strategies, and to analyze the problem of engine startability. The multi-zone model is capable of very accurate predictions of the combustion process, including HC and CO emissions. The multi-zone model h as applicability to the optimization of combustion chamber geometry and operating conditions to achieve controlled combustion at high efficiency and low emissions. On experimental work, we have done a thorough evaluation of operating conditions in a 4-cylinder Volkswagen TDI engine. The engine has been operated over a wide range of conditions by adjusting the …
Date:
May 14, 2001
Creator:
Aceves, Salvador M.; Flowers, Daniel L.; Martinez-Frias, Joel; Smith, J. Ray; Dibble, Robert; Au, Michael et al.
Object Type:
Article
System:
The UNT Digital Library
Major Leadership Election Contests in the Senate: A 27-Year Survey
None
Date:
November 14, 2001
Creator:
Amer, Mildred L.
Object Type:
Report
System:
The UNT Digital Library
From plasma immersion ion implantation to deposition: A historical perspective on principles and trends
Plasma immersion techniques of surface modification are known under a myriad of names. The family of techniques reaches from pure plasma ion implantation, to ion implantation and deposition hybrid modes, to modes that are essentially plasma film deposition with substrate bias. In the most general sense, all plasma immersion techniques have in common that the surface of a substrate (target) is exposed to plasma and that relatively high substrate bias is applied. The bias is usually pulsed. In this review, the roots of immersion techniques are explored, some going back to the 1800s, followed by a discussion of the groundbreaking works of Adler and Conrad in the 1980s. In the 1990s, plasma immersion techniques matured in theoretical understanding, scaling, and the range of applications. First commercial facilities are now operational. Various immersion concepts are compiled and explained in this review. While gas (often nitrogen) ion implantation dominated the early years, film-forming immersion techniques and semiconductor processing gained importance. In the 1980s and 1990s we have seen exponential growth of the field but signs of slowdown are clear since 1998. Nevertheless, plasma immersion techniques have found, and will continue to have, an important place among surface modification techniques.
Date:
June 14, 2001
Creator:
Anders, Andre
Object Type:
Article
System:
The UNT Digital Library
Tc-99 Analysis with Picogram Sensitivity by a Resin-Bead Mass-Spectrometric Isotope-Dilution Technique
This paper describes an improved isotope-dilution mass-spectrometric procedure. Important improvements are a highly selective (yet non-critical) isolation scheme devised primarily from the work of Maeck, et al. and a significant increase in the mass spectrometric ionization efficiency for technetium obtained by analyzing the technetium absorbed on individual anion exchange resin beads.
Date:
March 14, 2001
Creator:
Anderson, T. J.
Object Type:
Article
System:
The UNT Digital Library
Studies of Dynamic Properties of Shock Compressed FCC Crystals by in Situ Dynamic X-Ray Diffraction
There were 5 laser experiments conducted to date in FY-01 under the ongoing project to study the response of single crystal fcc materials under shock compression. An additional 10 laser shots are planned for August, 2001. This work has focused on developing capability to record diffraction from multiple lattice planes during the passage of a shock through a thin foil of single crystal copper, while simultaneously performing separate shock sample recovery experiments to study the residual deformation structure in the recovered samples.
Date:
August 14, 2001
Creator:
Baldis, H.; Kalantar, D. H.; Remington, B. A.; Belak, J.; Colvin, J.; Boehly, T. R. et al.
Object Type:
Report
System:
The UNT Digital Library
15th Street News (Midwest City, Okla.), Vol. 31, No. 2, Ed. 1 Friday, September 14, 2001
Newspaper from Rose State College in Midwest City, Oklahoma that includes national, local, and campus news along with advertising.
Date:
September 14, 2001
Creator:
Baldwin, Alisha
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
Impoundment and Sale of Cattle Trespassing on Federal Public Lands
This report explores the authority of BLM personnel regarding unauthorized cattle by reviewing the statutory authorities of BLM over the federal rangelands under its administration, and the regulations and administrative materials implementing those authorities in the context of grazing, trespass, impoundment and sale of unauthorized livestock.
Date:
August 14, 2001
Creator:
Baldwin, Pamela
Object Type:
Report
System:
The UNT Digital Library
Partial (gamma)-Ray Cross Sections for the Reaction 239Pu(n,2n(gamma)i) and the 239Pu(n,2n) Cross Section
Absolute partial {gamma}-ray cross sections for production of discrete {gamma} rays in the {sup 239}Pu(n,2n{gamma}i){sup 238}Pu reaction have been measured. The experiments were performed at LANSCE/WNR on the 60R flight line. Reaction {gamma}-rays were measured using the large-scale Compton-suppressed array of Ge detectors, GEANIE. The motivation for this experiment, an overview of the partial {gamma}-ray cross-section measurement, and an introduction to the main experimental issues will be presented. The energy resolution of the Ge detectors allowed identification of reaction {gamma} rays above the background of sample radioactivity and fission {gamma} rays. The use of planar Ge detectors with their reduced sensitivity to neutron interactions and improved line shape was also important to the success of this experiment. Absolute partial {gamma}-ray cross sections are presented for the 6{sub 1}{sup +} {yields} 4{sub 1}{sup +} member of the ground state rotational band in {sup 238}Pu, together with miscellaneous other {gamma}-ray partial cross sections. The n,2n reaction cross section shape and magnitude as a function of neutron energy was extracted from these partial cross sections using nuclear modeling (enhanced Hauser-Feshbach) to relate partial {gamma}-ray cross sections to the n,2n cross section. The critical nuclear modeling issue is the ratio of a partial cross …
Date:
September 14, 2001
Creator:
Beacker, J. A.; Bernstein, L. A.; Younes, W.; McNabb, D. P.; Garrett, P. E.; Archer, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Farm Commodity Programs: A Short Primer
This report briefly discusses programs designed to provide income support, price support, and/or supply management for approximately 20 specified agricultural commodities. USDA farm support programs represent the heart of U.S. farm policy, by virtue of their longevity – they have existed since the early 1930s – and their cost.
Date:
September 14, 2001
Creator:
Becker, Geoffrey S.
Object Type:
Report
System:
The UNT Digital Library
Addendum to the 200 West Area Dust Mitigation Strategies: Treatment of the Dust Source Area
This document describes the source area for the blowing dust encountered in the southwest portion of the 200 West Area. Strategies for short-term stabilization of the entire source area, short-term stabilization of a portion of the source area based on levels of respirable dust, and long-term stabilization of the entire source area are provided. An separate evaluation of aerosolized water as a means of reducing airborne dust is also provided.
Date:
May 14, 2001
Creator:
Becker, James M. & Sackschewsky, Michael R.
Object Type:
Report
System:
The UNT Digital Library
The Colony Courier-Leader (The Colony, Tex.), Vol. 20, No. 18, Ed. 1 Thursday, June 14, 2001
Weekly newspaper from The Colony, Texas that includes local, state, and national news along with advertising.
Date:
June 14, 2001
Creator:
Beesley, Tom
Object Type:
Newspaper
System:
The Portal to Texas History
Numerical simulation of premixed turbulent methane combustion
In this paper we study the behavior of a premixed turbulent methane flame in three dimensions using numerical simulation. The simulations are performed using an adaptive time-dependent low Mach number combustion algorithm based on a second-order projection formulation that conserves both species mass and total enthalpy. The species and enthalpy equations are treated using an operator-split approach that incorporates stiff integration techniques for modeling detailed chemical kinetics. The methodology also incorporates a mixture model for differential diffusion. For the simulations presented here, methane chemistry and transport are modeled using the DRM-19 (19-species, 84-reaction) mechanism derived from the GRIMech-1.2 mechanism along with its associated thermodynamics and transport databases. We consider a lean flame with equivalence ratio 0.8 for two different levels of turbulent intensity. For each case we examine the basic structure of the flame including turbulent flame speed and flame surface area. The results indicate that flame wrinkling is the dominant factor leading to the increased turbulent flame speed. Joint probability distributions are computed to establish a correlation between heat release and curvature. We also investigate the effect of turbulent flame interaction on the flame chemistry. We identify specific flame intermediates that are sensitive to turbulence and explore various correlations …
Date:
December 14, 2001
Creator:
Bell, John B.; Day, Marcus S. & Grcar, Joseph F.
Object Type:
Article
System:
The UNT Digital Library
Stochastic algorithms for the analysis of numerical flame simulations
Recent progress in simulation methodologies and new, high-performance parallel architectures have made it is possible to perform detailed simulations of multidimensional combustion phenomena using comprehensive kinetics mechanisms. However, as simulation complexity increases, it becomes increasingly difficult to extract detailed quantitative information about the flame from the numerical solution, particularly regarding the details of chemical processes. In this paper we present a new diagnostic tool for analysis of numerical simulations of combustion phenomena. Our approach is based on recasting an Eulerian flow solution in a Lagrangian frame. Unlike a conventional Lagrangian viewpoint in which we follow the evolution of a volume of the fluid, we instead follow specific chemical elements, e.g., carbon, nitrogen, etc., as they move through the system. From this perspective an ''atom'' is part of some molecule that is transported through the domain by advection and diffusion. Reactions ca use the atom to shift from one species to another with the subsequent transport given by the movement of the new species. We represent these processes using a stochastic particle formulation that treats advection deterministically and models diffusion as a suitable random-walk process. Within this probabilistic framework, reactions can be viewed as a Markov process transforming molecule to molecule …
Date:
December 14, 2001
Creator:
Bell, John B.; Day, Marcus S.; Grcar, Joseph F. & Lijewski, Michael J.
Object Type:
Article
System:
The UNT Digital Library
Detailed modeling and laser-induced fluorescence imaging of nitric oxide in a NH(i)-seeded non-premixed methane/air flame
In this paper we study the formation of NO in laminar, nitrogen diluted methane diffusion flames that are seeded with ammonia in the fuel stream. We have performed numerical simulations with detailed chemistry as well as laser-induced fluorescence imaging measurements for a range of ammonia injection rates. For comparison with the experimental data, synthetic LIF images are calculated based on the numerical data accounting for temperature and fluorescence quenching effects. We demonstrate good agreement between measurements and computations. The LIF corrections inferred from the simulation are then used to calculate absolute NO mole fractions from the measured signal.The NO formation in both doped and undoped flames occurs in the flame sheet. In the undoped flame, four different mechanisms including thermal and prompt NO appear to contribute to NO formation. As the NH3 seeding level increases, fuel-NO becomes the dominant mechanism and N2 shifts from being a net reactant to being a net product. Nitric oxide in the undoped flame as well as in the core region of the doped flames are underpredicted by the model; we attribute this mainly to inaccuracies in the NO recycling chemistry on the fuel-rich side of the flame sheet.
Date:
December 14, 2001
Creator:
Bell, John B.; Day, Marcus S.; Grcar, Joseph F.; Bessler, Wolfgang G.; Schulz, Christof; Glarborg, Peter et al.
Object Type:
Article
System:
The UNT Digital Library
Rare Decay Results from KTeV and ({rho}{sub CKM}, {eta}{sub CKM})
Rare decay results from KTeV are reviewed, emphasizing modes that in principle provide information about the CKM matrix. The KTeV results shown here are from the 1997 data sample, which consists of about 2.7 x 10{sup 11} K{sub L}{sup 0} decay samples. KTeV also took data in 1999, giving a total data sample about 2.5 times what is presented here for three body decays and about 3.2 times what is presented here for four body decays. A summary of the KTeV detector is in the Appendix. Our recent results in lepton flavor violating modes are also presented.
Date:
February 14, 2001
Creator:
Bellantoni, L.
Object Type:
Article
System:
The UNT Digital Library
The influence of cut off lows on sulfate burdens over the North Atlantic during April, 1987
The authors have presented examples from a modeling study of the development of sulfur burdens over North America, the North Atlantic Ocean and Europe during April, 1987 using observation-derived meteorological data to represent the actual conditions for this period, focusing on the influence of cut-off lows on SO{sub 2} and sulfate column burdens over the North Atlantic Ocean. The analysis demonstrates that these systems can serve either as sources or sinks of sulfate, and that the major factor governing their resulting effect is the position during its formative stages relative to (a) sources of moisture, and (b) sulfur emissions, which regulates the availability of sulfur, cloud liquid water for sulfur oxidation, and the amount of precipitation for sulfate removal produced in the later stages of the life cycle.
Date:
January 14, 2001
Creator:
Benkovitz, C. M.; Miller, M. A.; Schwartz, S. E. & Kwon, O. U.
Object Type:
Article
System:
The UNT Digital Library
FY2001 Annual Report for EMSP Project #70108: Effects of Fluid Distribution on Measured Geophysical Properties for Partially Saturated, Shallow Subsurface Conditions
Our goal is to improve geophysical imaging of the vadose zone. We will achieve this goal by providing new methods to improve interpretation of field data. The purpose of this EMSP project is to develop relationships between laboratory measured geophysical properties and porosity, saturation, and fluid distribution, for partially saturated soils. Algorithms for relationships between soil composition, saturation, and geophysical measurements will provide new methods to interpret geophysical field data collected in the vadose zone at sites such as Hanford, WA.
Date:
June 14, 2001
Creator:
Berge, P. A.; Bonner, B. P.; Roberts, J. J.; Wildenschild, D.; Aracne-Ruddle, C. M.; Berryman, J. G. et al.
Object Type:
Report
System:
The UNT Digital Library
Oral History Interview with William C. Beyer, March 14, 2001
The National Museum of the Pacific War presents an oral interview with William C. Beyer. Beyer grew up in Texas and joined the Marines in January 1942. After training, he was assigned to the third division in artillery. He departed on the USS Mount Vernon for New Zealand. He anecdotes about meeting with some Maori people. Then he departed on the Cresent City for Guadalcanal in May 1943. From Guadalcanal he left for Bougainville in November 1943. He describes being caught in a foxhole for two days without communication. He also listened to Tokyo Rose on the radio. The Army relieved the Marines January 15, 1944, and his unit returned to Guadalcanal. On July 21, 1944, they landed on Guam and went into battle. Next Beyer left for Iwo Jima. The Third Marine Division was assigned to the central area of the island. He witnessed the raising of the flag. On the 50th anniversary of the war, Beyer and his wife returned to New Zealand and Guam.
Date:
March 14, 2001
Creator:
Beyer, William C.
Object Type:
Sound
System:
The Portal to Texas History
Oral History Interview with William C. Beyer, March 14, 2001
The National Museum of the Pacific War presents an oral interview with William C. Beyer. Beyer grew up in Texas and joined the Marines in January 1942. After training, he was assigned to the third division in artillery. He departed on the USS Mount Vernon for New Zealand. He anecdotes about meeting with some Maori people. Then he departed on the Cresent City for Guadalcanal in May 1943. From Guadalcanal he left for Bougainville in November 1943. He describes being caught in a foxhole for two days without communication. He also listened to Tokyo Rose on the radio. The Army relieved the Marines January 15, 1944, and his unit returned to Guadalcanal. On July 21, 1944, they landed on Guam and went into battle. Next Beyer left for Iwo Jima. The Third Marine Division was assigned to the central area of the island. He witnessed the raising of the flag. On the 50th anniversary of the war, Beyer and his wife returned to New Zealand and Guam.
Date:
March 14, 2001
Creator:
Beyer, William C.
Object Type:
Text
System:
The Portal to Texas History
Effect of Internal Alpha Radiation on Borosilicate Glass Containing Simulated Radioactive Waste
To evaluate borosilicate glass as a matrix for long-term storage of radioactive waste, samples containing 45 wt. percent simulated waste along with 0.5 wt. percent 244Cm or 1 wt. percent 238Pu as alpha particle emitters were synthesized. A glass containing 238Pu without simulated waste was also made. Effects of internal alpha radiolysis from 244Cm and 238Pu on physical stability, leachability, and dilatation of the glasses were examined. Results confirm that glass may be a desirable matrix for fixing SRP radioactive waste for long-term storage. Internal alpha radiolysis and helium accumulation in the small samples did not significantly damage the glass. Actual values for helium solubility and permeability would be necessary, however, to determine whether helium accumulation might eventually damage larger glass monoliths during long-term storage.
Date:
March 14, 2001
Creator:
Bibler, N.E.
Object Type:
Article
System:
The UNT Digital Library
Optimization of Processing and Modeling Issues for Thin Film Solar Cell Devices Including Concepts for the Development of Polycrystalline Multijunctions Annual Subcontract Report, 24 August 1999 - 23 August 2000
This report describes the results achieved during Phase I of a three-phase subcontract to develop and understand thin-film solar cell technology associated with CuInSe2 and related alloys, a-Si and its alloys, and CdTe. Modules based on all these thin films are promising candidates to meet DOE long-range efficiency, reliability, and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for developing viable commercial processes and to improve module performance. The generic research issues addressed are: (1) quantitative analysis of processing steps to provide information for efficient commercial-scale equipment design and operation; (2) device characterization relating the device performance to materials properties and process conditions; (3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; (4) development of improved window/heterojunction layers and contacts to improve device performance and reliability; and (5) evaluation of cell stability with respect to illumination, temperature, and ambient, and with respect to device structure and module encapsulation.
Date:
November 14, 2001
Creator:
Birkmire, R. W.; Phillips, J. E.; Shafarman, W. N.; Eser, E.; Hegedus, S. S. & McCandless, B. E.
Object Type:
Report
System:
The UNT Digital Library
PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ON SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND.
The much anticipated RHIC spin physics program will commence this fall when the first physics run with colliding beams of polarized protons is expected. More specifically, the planned year-1 RHIC-Spin measurements are (1) the double-spin asymmetry A{sub LL}{sup {pi}} in production of pions by collisions of longitudinally polarized protons (in order to obtain first information on the proton's spin-dependent gluon density, {Delta}g); (2) the transverse single-spin asymmetry A{sub N}{sup {pi}} for pion production. These two reactions provided part of the motivation for our workshop. On the first day there were informative talks on the specific plans of STAR (by Rakness) and PHENIX (by Goto) for the polarized run of Year-1. Some of the theoretical questions related to the double-spin asymmetry A{sub LL}{sup {pi}} were discussed on the first day by Vogelsang and Kretzer, which centered mostly around the questions of how well the unpolarized fragmentation functions are known, the need for next-to-leading order calculations, and on how sensitive the asymmetry is to the possible {Delta}g distributions. Vetterli presented HERMES measurements of fragmentation functions, which overlap in Q{sup 2} with the future lower-p{sub T} measurements at RHIC.
Date:
May 14, 2001
Creator:
Bland, L.; Boer, D.; Saito, N. & Vogelsang, W.
Object Type:
Report
System:
The UNT Digital Library
Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance
This project involves the design and synthesis of receptors for oxoanions of environmental importance and specifically those found in high level waste tanks. Polyammonium macrocycles as receptors and nitrate as anion were the focus of the first phase of this project. A second phase involved the synthesis of lipophilic amide-based receptors in order to increase the potential for obtaining workable receptors for both separations and sensing applications on site. A three tier approach was employed: I. Design, synthesis, and physical and structural characterization of receptors; II. Examination of the technique known as ITIES, Interface Between Two Immiscible Electrolyte Solutions, as an analytical probe for anion analysis; and III. Investigation of dual ion pair extraction using lipophilic amide receptors for anion binding. More recent efforts in the renewal of this project are focusing on sulfate and new designs for receptors. These efforts will also have impact on low activity waste, for example in the vitrification process.
Date:
June 14, 2001
Creator:
Bowman-James, Kristin; Wilson, George S. & Moyer, Bruce
Object Type:
Report
System:
The UNT Digital Library
Ductilization of Cr via Oxide Dispersions
Work by Scruggs et al. in the 1960's demonstrated that up to 20% tensile ductility could be achieved at room-temperature in sintered and extruded powder metallurgical Cr alloyed with MgO. During sintering, much of the MgO converts to a MgCr{sub 2}O{sub 4} spinel, which was hypothesized to getter nitrogen from the Cr, rendering it ductile. Recent efforts at Oak Ridge National Laboratory (ORNL) have succeeded in duplicating this original effect. Preliminary results suggest that the ductilization mechanism may be more complicated than the simple nitrogen gettering mechanism proposed by Scruggs, as some ductility was observed at room-temperature in Cr-MgO alloys containing nitride precipitates. Results of microstructural characterization and room-temperature mechanical property studies are presented for Cr-6MgO-(0-2.2)Ti wt.% as a function of hot-pressing and extrusion. Possible mechanisms by which the MgO additions may improve the room-temperature ductility of Cr are discussed.
Date:
February 14, 2001
Creator:
Brady, M.P.
Object Type:
Article
System:
The UNT Digital Library