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An Adaptive Linearization Method for a Constraint Satisfaction Problem in Semiconductor Device Design Optimization

Description: The device optimization is a very important element in semiconductor technology advancement. Its objective is to find a design point for a semiconductor device so that the optimized design goal meets all specified constraints. As in other engineering fields, a nonlinear optimizer is often used for design optimization. One major drawback of using a nonlinear optimizer is that it can only partially explore the design space and return a local optimal solution. This dissertation provides an adaptive optimization design methodology to allow the designer to explore the design space and obtain a globally optimal solution. One key element of our method is to quickly compute the set of all feasible solutions, also called the acceptability region. We described a polytope-based representation for the acceptability region and an adaptive linearization technique for device performance model approximation. These efficiency enhancements have enabled significant speed-up in estimating acceptability regions and allow acceptability regions to be estimated for a larger class of device design tasks. Our linearization technique also provides an efficient mechanism to guarantee the global accuracy of the computed acceptability region. To visualize the acceptability region, we study the orthogonal projection of high-dimensional convex polytopes and propose an output sensitive algorithm for projecting polytopes into two dimensions.
Date: May 1999
Creator: Chang, Chih-Hui, 1967-
Partner: UNT Libraries

Comparative Biochemistry and Evolution of Aspartate Transcarbamoylase from Diverse Bacteria

Description: Aspartate transcarbamoylase (ATCase) catalyzes the first committed step in pyrimidine biosynthesis. Bacterial ATCases are divided into three classes, A, B and C. Class A ATCases are largest at 450-500, are. dodecamers and represented by Pseudomonas ATCase. The overlapping pyrBC' genes encode the Pseudomonases ATCase, which is active only as a 480 kDa dodecamer and requires an inactive pyrC'-encoded DHOase for ATCase activity. ATCase has been studied in two non-pathogenic members of Mycobacterium, M. smegmatis and M. phlei. Their ATCases are dodecamers of molecular weight 480 kDa, composed of six PyrB and six PyrC polypeptides. Unlike the Pseudomonas ATCase, the PyrC polypeptide in these mycobacteria encodes an active DHOase. Moreover, the ATCase: DHOase complex in M. smegmatis is active both as the native 480 kDa and as a 390 kDa complex. The latter lacks two PyrC polypeptides yet retains ATCase activity. The ATCase from M. phlei is similar, except that it is active as the native 480 kDa form but also as 450,410 and 380 kDa forms. These complexes lack one, two, and three PyrC polypeptides, respectively. By contrast,.ATCases from pathogenic mycobacteria are active only at 480 kDa. Mycobacterial ATCases contain active DHOases and accordingly. are placed in class A1 . The class A1 ATCases contain active DHOases while class A2 ATCases contain inactive DHOases. ATCase has also been purified from Burkholderia cepacia and from an E. coli strain in which the cloned pyrB of B. cepacia was expressed. The B. cepacia ATCase has a molecular mass of 550 kDa, with two different polypeptides, PyrB (52 kDa) and PyrC of (39 kDa). The enzyme is active both as the native enzyme at 550 kDa and as smaller molecular forms including 240 kDa and 165 kDa. The ATCase synthesized by the cloned pyrB gene has a molecular weight of 165 kDa composed ...
Date: May 1999
Creator: Hooshdaran, Massoumeh Ziba
Partner: UNT Libraries

The Effect of Quality and Color Visual Aids on Immediate Recall, Attitude Toward Speaker, and Attitude Toward Speech

Description: Thirty years of empirical research on visual aids have produced inconsistent results--perhaps because the quality and color of those visuals were inconsistent. The purpose of this study was to determine what effects quality and color of instructional transparencies used in an informative speech have on listener recall and attitudes toward speaker and speech. A total of 709 community college and university students in 36 intact classes were randomly assigned to one of four visual treatment groups (poor-quality black/white, high-quality black/white, poor-quality color, or high-quality color) or one of two control groups (no-speech or no-visuals). A videotaped speech was projected onto a large screen at the right of the room; visual aids (each shown for approximately 30 seconds) were projected onto another screen set immediately to the left. Recall was measured by a 10-item multiple choice test; attitude toward speech and speaker were each measured by six seven-item semantic differential scales. Analysis of variance indicated that the type of transparencies used in an informative speech have a definite effect on immediate recall and attitude toward the speech, but no effect on attitude toward speaker. All four treatment groups scored significantly higher on recall than the no-speech and no-visual control groups. Log percent of change showed poor color to produce the lowest scores (still 13% better than control) and quality color to produce the highest scores (19.5'% better). Analysis found listeners to have a more positive attitude toward the speech when quality color, quality black/white, or poor black/white visuals were used. It appears that any visual (even a poor quality one) produces better recall than no visuals. Speakers with the time to produce quality visuals should add color; speakers who pay little attention to quality would be advised to use black/white visuals. Implications for future research are suggested.
Date: May 1999
Creator: Hamilton, Cheryl A. (Cheryl Ann)
Partner: UNT Libraries

Isolation and Characterization of a New Capsule-Forming Bacterium

Description: A unique, previously undescribed Gram-negative bacterium was isolated from several soils in Texas and extensively characterized in this study. The cells measured 1-2 by 4-6 μm. The distinguishing characteristic of the bacterium is the extraordinary capsular material which surrounds the cells. The new isolates are aerobic, mesophilic, non motile and have the ability to utilize a variety of organic compounds as the sole source of carbon and energy. The organism grows optimally at 30° C and the optimal pH lies between 7.0-8.0. The isolates produce catalase but oxidase is not produced. They do not produce indole or hydrogen sulfide. The organism can hydrolyze gelatin and Tween 80 but not starch, esculin and casein. The major cellular fatty acid is anteiso 15:0. The guanine and cytosine content is 58-62 mole%. The organism's taxonomic position was further established by specific gene probes, 16S rRNA homology, DNA homology and "ribotyping." These data showed that it was most closely related to members of the genus Paenibacillus, although somewhat divergent from other species classified in this genus. After careful evaluation of the results obtained during this study, it is proposed that this unique bacterium be named Paenibacillus velasolus sp. nov.
Date: May 1999
Creator: Thongmee, Acharawan
Partner: UNT Libraries

The Many Battles of Glorieta Pass: Struggles for the Integrity of a Civil War Battlefield

Description: This study focuses on modern-day attempts to preserve the site where Union volunteers from Colorado defeated a Confederate army from Texas at the 1862 Battle of Glorieta Pass to curtail Confederate expansion westward. When construction workers in 1987 accidently uncovered remains of the war dead, a second battle of Glorieta Pass ensued. Texas and New Mexico officials quarreled over jurisdiction of the war casualties. Eventually Congress authorized the National Park Service to expand the Pecos National Park through purchase and donation of land to include the battlesite. Sources include local records, newspapers, federal and state documents, and interviews with preservation participants.
Date: August 1999
Creator: Hull, William Edward, 1945-
Partner: UNT Libraries

An Analysis of a Title I Inclusive Middle School Program in Texas over a Three Year Period: A Case Study

Description: The purpose of this study was to describe a Title I inclusion program in a north Texas middle school, to evaluate the degree of its success as a high achieving program, and to analyze how closely it met the requirements of the Improving America's Schools Act of 1994. Data were collected from the learning facilitators and teachers at the middle school with the permission of the school district. This study began with extensive research on the nature of adolescents and the beliefs and characteristics of high achieving middle schools. It addressed the steps which were recommended in the literature to improve middle schools and benefit students that are at-risk of failing to master the curriculum at their grade level. The researcher concluded by reporting effective strategies being used in middle school at-risk programs. These are strategies noted by experts as successful in identified programs. The population for this study was seventh and eighth grade Title I students who attended middle school during the 1992-1993, 1993-1994, 1994-1995 and 1995-1996 school years. The data collected by the researcher are presented in two parts: the description of the Title I inclusion program; and the results of the Texas Assessment of Academic Skills tests in reading and math, the Shaw-Hiehle Math Tests, and the Gates-MacGinitie Reading Tests. Findings from this study suggest that the program met the requirements of a Title I program established by the federal government. The test scores for the middle school improved during the three years of the program. The Title I inclusion program met the requirements of the Improving America's Schools Act. Finally, the Title I students were successful working in classrooms with other students on challenging curriculum which met the State's content and performance standards. These findings have implications for other middle schools who are developing Title I ...
Date: May 1999
Creator: Restivo, Janet DiMaria
Partner: UNT Libraries

Brief Symptom Inventory: Music and Non-Music Students

Description: The present study is a comparison of music and non-music students with respect to their response patterns on the Brief Symptom Inventory as well as several demographic questions. The sample consisted of 148 non-music students and 141 music students at three levels: (1) freshmen/sophomore; (2) juniors/seniors; and (3) graduate students. Music students consisted of volunteers from several different music classes and non-music students were volunteers from non-music classes. There were no significant differences found among or between groups for the BSI subscales. However, music students were significantly less likely to have gone to counseling in the past and to seek professional counseling for future problems. Recommendations for psycho-educational interventions with musicians are discussed as well as suggestions for future research.
Date: August 1999
Creator: Young, James A. (James Alan), 1968-
Partner: UNT Libraries

Mutagenized HLA DNA Constructs: Tools for Validating Molecular HLA Typing Methodologies

Description: This study describes the development and validation of mutagenized cloned DNA constructs, which correspond to the polymorphic regions of the class II region of the HLA complex. The constructs were used to verify the allelic specificity of primers and probes in polymerase chain reaction (PCR)-based HLA typing assays such as Sequence Specific Primers (SSP) and Sequence Specific Oligonucleotide Probes (SSOP). The constructs consisted of the entire polymorphic region of exon 2 of class II HLA allele sequences that included primer annealing sites or probe hybridization sites. An HLA allele sequence was inserted into a plasmid, cloned, then mutagenized to match a specific HLA allele, and finally, the correct clone was verified by bidirectional sequencing of the insert. Thus, the construct created a cloned reference DNA sample for any specific allele, and can be used to validate the accuracy of various molecular methodologies.
Date: May 1999
Creator: Schulte, Kathleen Q.
Partner: UNT Libraries

Digitizing Historical Publications: Enhancing the Official Electronic Collection of the Advisory Commission on Intergovernmental Relations

Description: This report discusses a project for digitizing historical publications and making them available online. The authors' goal will be to develop a process that balances level of access with the cost of digitizing and making the data available on the Internet.
Date: April 1999
Creator: Hartman, Cathy Nelson
Partner: UNT Libraries

[Murchison Performing Center-opening gala]

Description: Video footage of the One O'Clock Lab band, wind symphony with grand chorus, and symphony orchestra with grand chorus performing at the Murchison Performing Arts Center opening gala. The video ends with a fireworks display.
Date: February 20, 1999
Creator: Center for Media Production
Partner: UNT Libraries Special Collections

Biodiversity of Dragonflies and Damselflies (Odonata) of the South-Central Nearctic and Adjacent Neotropical Biotic Provinces

Description: The south-central United States serves as an important biogeographical link and dispersal corridor between Nearctic and Neotropical elements of western hemisphere odonate faunas. Its species are reasonably well known because of substantial collections, but there has been no concerted effort to document the extent of biodiversity and possible geographic affinities of dragonflies and damselflies of this region. The recent discoveries of Argia leonorae Garrison, Gomphus gonzalezi Dunkle and Erpetogomphus heterodon Garrison from southern and western Texas and northern Mexico suggest that Odonata species remain to be discovered in this area, particularly from far south Texas and northern Mexico. I have documented a total of 12,515 records of Odonata found in 408 counties within the south-central U.S. A total of 73 species of damselflies and 160 species of dragonflies was revealed in the region. The 233 (197 in Texas) Odonata species are distributed among 10 families and 66 genera. Illustrated family, generic, and species-level keys are provided. Since the beginning of this work in the Fall of 1993, one species has been added each to the Louisiana and Oklahoma faunas, and 12 species have been added, previously unreported from Texas, including four new to the U.S. The area of highest Odonata biodiversity overall (161 spp.) is in the Austroriparian biotic province. The greatest degree of faunal similarity between the south-central U.S. and other intra-continental regions was observed for the eastern (64%) United States. Diversity is a function of area, and as expected, the numbers of breeding birds and Odonata, in each contiguous U.S. state are positively correlated (r=0.376, n=33, p=0.031). There is, however, no strong correlation between land area and species diversity within the region, but those natural biotic provinces (Austroriparian, Texan, Balconian) where aquatic systems and topographic heterogeneity are the greatest provide a broader spectrum of potential Odonata habitats and ...
Date: May 1999
Creator: Abbott, John C.
Partner: UNT Libraries

Development of small, fast reactor core designs using lead-based coolant.

Description: A variety of small (100 MWe) fast reactor core designs are developed, these include compact configurations, long-lived (15-year fuel lifetime) cores, and derated, natural circulation designs. Trade studies are described which identify key core design issues for lead-based coolant systems. Performance parameters and reactivity feedback coefficients are compared for lead-bismuth eutectic (LBE) and sodium-cooled cores of consistent design. The results of these studies indicate that the superior neutron reflection capability of lead alloys reduces the enrichment and burnup swing compared to conventional sodium-cooled systems; however, the discharge fluence is significantly increased. The size requirement for long-lived systems is constrained by reactivity loss considerations, not fuel burnup or fluence limits. The derated lead-alloy cooled natural circulation cores require a core volume roughly eight times greater than conventional compact systems. In general, reactivity coefficients important for passive safety performance are less favorable for the larger, derated configurations.
Date: June 11, 1999
Creator: Cahalan, J. E.; Hill, R. N.; Khalil, H. S. & Wade, D. C.
Partner: UNT Libraries Government Documents Department

Alternatives to conventional diesel fuel-some potential implications of California's TAC decision on diesel particulate.

Description: Limitations on the use of petroleum-based diesel fuel in California could occur pursuant to the 1998 declaration by California's Air Resources Board (CARB) that the particulate matter component of diesel exhaust is a carcinogen, therefore a toxic air contaminant (TAC) subject to provisions of the state's Proposition 65. It is the declared intention of CARB not to ban or restrict diesel fuel, per se, at this time. Assuming no total ban, Argonne National Laboratory (ANL) explored two feasible ''mid-course'' strategies. (1) Increased penetration of natural gas and greater gasoline use in the transportation fuels market, to the extent that some compression-ignition (CI) applications revert to spark-ignition (SI) engines. (2) New specifications requiring diesel fuel reformulation based on exhaust products of individual diesel fuel constituents. Each of these alternatives results in some degree of (conventional) diesel displacement. In the first case, diesel fuel is assumed admissible for ignition assistance as a pilot fuel in natural gas (NG)-powered heavy-duty vehicles, and gasoline demand in California increases by 32.2 million liters per day overall, about 21 percent above projected 2010 baseline demand. Natural gas demand increases by 13.6 million diesel liter equivalents per day, about 7 percent above projected (total) consumption level. In the second case, compression-ignition engines utilize substitutes for petroleum-based diesel having similar ignition and performance properties. For each case we estimated localized air emission plus generalized greenhouse gas and energy changes. Economic implications of vehicle and engine replacement were not evaluated.
Date: August 10, 1999
Creator: Eberhardt, J. J.; Rote, D. M.; Saricks, C. L. & Stodolsky, F.
Partner: UNT Libraries Government Documents Department

Performance Assessment Uncertainty Analysis for Japan's HLW Program Feasibility Study (H12)

Description: Most HLW programs in the world recognize that any estimate of long-term radiological performance must be couched in terms of the uncertainties derived from natural variation, changes through time and lack of knowledge about the essential processes. The Japan Nuclear Cycle Development Institute followed a relatively standard procedure to address two major categories of uncertainty. First, a FEatures, Events and Processes (FEPs) listing, screening and grouping activity was pursued in order to define the range of uncertainty in system processes as well as possible variations in engineering design. A reference and many alternative cases representing various groups of FEPs were defined and individual numerical simulations performed for each to quantify the range of conceptual uncertainty. Second, parameter distributions were developed for the reference case to represent the uncertainty in the strength of these processes, the sequencing of activities and geometric variations. Both point estimates using high and low values for individual parameters as well as a probabilistic analysis were performed to estimate parameter uncertainty. A brief description of the conceptual model uncertainty analysis is presented. This paper focuses on presenting the details of the probabilistic parameter uncertainty assessment.
Date: August 30, 1999
Partner: UNT Libraries Government Documents Department

Hybrid options for light-duty vehicles.

Description: Hybrid electric vehicles (HEVs) offer great promise in improving fuel economy. In this paper, we analyze why, how, and by how much vehicle hybridization can reduce energy consumption and improve fuel economy. Our analysis focuses on efficiency gains associated solely with vehicle hybridization. We do not consider such other measures as vehicle weight reduction or air- and tire-resistance reduction, because such measures would also benefit conventional technology vehicles. The analysis starts with understanding the energy inefficiencies of light-duty vehicles associated with different operation modes in US and Japanese urban and highway driving cycles, with the corresponding energy-saving potentials. The potential for fuel economy gains due to vehicle hybridization can be estimated almost exclusively on the basis of three elements: the reducibility of engine idling operation, the recoverability of braking energy losses, and the capability of improving engine load profiles to gain efficiency associated with specific HEV configurations and control strategies. Specifically, we evaluate the energy efficiencies and fuel economies of a baseline MY97 Corolla-like conventional vehicle (CV), a hypothetical Corolla-based minimal hybrid vehicle (MHV), and a MY98 Prius-like full hybrid vehicle (FHV). We then estimate energy benefits of both MHVs and FHVs over CVs on a performance-equivalent basis. We conclude that the energy benefits of hybridization vary not only with test cycles, but also with performance requirements. The hybrid benefits are greater for ''Corolla (high) performance-equivalent'' vehicles than for ''Prius (low) performance-equivalent'' vehicles. An increasing acceleration requirement would result in larger fuel economy benefits from vehicle hybridization.
Date: July 19, 1999
Creator: An, F., Stodolsky, F. & Santini, D.
Partner: UNT Libraries Government Documents Department

Residual Stress Predictions in Polycrystalline Alumina

Description: Microstructure-level residual stresses arise in polycrystalline ceramics during processing as a result of thermal expansion anisotropy and crystallographic disorientation across the grain boundaries. Depending upon the grain size, the magnitude of these stresses can be sufficiently high to cause spontaneous microcracking during the processing of these materials. They are also likely to affect where cracks initiate and propagate under macroscopic loading. The magnitudes of residual stresses in untextured and textured alumina samples were predicted using object oriented finite (OOF) element analysis and experimentally determined grain orientations. The crystallographic orientations were obtained by electron-backscattered diffraction (EBSD). The residual stresses were lower and the stress distributions were narrower in the textured samples compared to those in the untextured samples. Crack initiation and propagation were also simulated using the Griffith fracture criterion. The grain boundary to surface energy ratios required for computations were estimated using AFM groove measurements.
Date: December 13, 1999
Partner: UNT Libraries Government Documents Department

Reactivation of an Idle Lease to Increase Heavy Oil Recovery through Application of Conventional Steam Drive Technology in a Low Dip Slope & Reservoir in the Midway-Sunset Field, San Jaoquin Basin, California

Description: In January 1997 the project entered its second and main phase with the purpose of demonstrating whether steamflood can be a more effective mode of production of the heavy, viscous oils from the Monarch Sand reservoir than the more conventional cyclic steaming. The objective is not just to produce the pilot site within the Pru Fee property south of Taft (Figure 1), but to test which production parameters optimize total oil recovery at economically acceptable rates of production and production costs.
Date: November 9, 1999
Creator: Schamel, Steven
Partner: UNT Libraries Government Documents Department

High-power vacuum window in WR10

Description: Results are presented for fabrication and test of a WR10 waveguide window, for use in ultra-high vacuum at 91.4 GHz. Low-power bench measurements are compared with analytic and simulation results. Operation at approximately equal to 4-kW peak power, duty factor 10{sup {minus}6} and 10{sup {minus}9}-scale vacuum is noted.
Date: June 28, 1999
Creator: Hill, Marc E
Partner: UNT Libraries Government Documents Department

Laser-generated metallic hydrogen

Description: Hydrogen reaches the minimum conductivity of a metal at 140 GPa (1.4 Mbar) and 3000 K. These conditions were achieved using a two-stage light-gas gun. The authors have investigated computationally the use of a laser-heated hohlraum to shock compress hydrogen to these conditions in samples sufficiently thin that the metallic fluid might be quenched metastably on release of dynamic pressure. A configuration was found such that the duration of maximum pressure is sufficiently long that the hydrogen film cools by thermal conduction before pressure is released.
Date: August 27, 1999
Creator: Nellis, W J & Pollaine, S M
Partner: UNT Libraries Government Documents Department

THE ECONOMICAL PRODUCTION OF ALCOHOL FUELS FROM COAL-DERIVED SYNTHESIS GAS. Includes quarterly technical progress report No.25 from 10/01/1997-12/31/1997, and quarterly technical progress report No.26 from 01/01/1998-03/31/1998

Description: This project was divided into two parts. One part evaluated possible catalysts for producing higher-alcohols (C{sub 2} to C{sub 5+}) as fuel additives. The other part provided guidance by looking both at the economics of mixed-alcohol production from coal-derived syngas and the effect of higher alcohol addition on gasoline octane and engine performance. The catalysts studied for higher-alcohol synthesis were molybdenum sulfides promoted with potassium. The best catalysts produced alcohols at a rate of 200 g/kg of catalyst/h. Higher-alcohol selectivity was over 40%. The hydrocarbon by-product was less than 20%. These catalysts met established success criteria. The economics for mixed alcohols produced from coal were poor compared to mixed alcohols produced from natural gas. Syngas from natural gas was always less expensive than syngas from coal. Engine tests showed that mixed alcohols added to gasoline significantly improved fuel quality. Mixed-alcohols as produced by our catalysts enhanced gasoline octane and decreased engine emissions. Mixed-alcohol addition gave better results than adding individual alcohols as had been done in the 1980's when some refiners added methanol or ethanol to gasoline.
Date: March 1, 1999
Partner: UNT Libraries Government Documents Department