Electronic Theses, Dissertations, and Records of Study (2002– )

Permanent URI for this collection

http://hdl.handle.net/1969.1/2

Description

This collection contains Texas A&M University theses and dissertations written after 2002.

History

In 2002, the Texas A&M University’s Office of Graduate and Professional Studies (OGAPS) began accepting electronic submission of theses and dissertations. In 2004, electronic submission became a requirement, and OGAPS now also accepts electronically submitted records of study.

Access

Most theses and dissertations in this collection are open access. However, Texas A&M University students have a right to place their work under embargo in certain circumstances. The full-text of theses and dissertations under embargo is restricted until the embargo period has expired.

Website: Thesis and Dissertation Services

Browse

Now showing 1 - 20 of 24048

The Expression of Gender in Synthetic Actors: Modeling and Motion Control Over Invariant Perceptual Cues Leading to Gender Recognition
(Texas A&M University, 1994-05) McLaughlin, Timothy David; Tassinary, Louis G.; Van Baerle, Susan L.; Alameldin, Tarek; Shebilske, Wayne L.
A perception based strategy for communicating the gender of computer animated characters is evaluated. Motivated by the idea that effective character animation involves the expression of character traits through motion, this study builds upon previous work in the areas of computer animation and ecological psychology in an effort to more fully characterize the dynamic information which leads to the perception of gender. Information specifying the masculinity or femininity of a walking figure is considered in relation to the range across which the indexes may be exaggerated and applied to objects not normally considered male or female.
A Comparison of Interactive Color Specification Systems for Human-Computer Interfaces
(Texas A&M University, 1994-12) Wells, Evelyn Frances; Tassinary, Louis G.; Leggett, John J.; House, Donald H.
Color specification is a time-consuming and challenging task in computer graphics applications. The purpose of this research is to examine the color specification process in the context of current human-computer interface technology, and to investigate how certain attributes of a color specification system affect its usability during a visual color matching task. Eighteen color specification systems are compared, each composed of different combinations of color space (red-green-blue, RGB; opponent channel, OPP; hue-saturation-value, HSV), slider type (plain, static, dynamic), and background context (achromatic, chromatic). A total of 83 undergraduate students, both male and female, participated in the study. Each subject completed six trials, with each trial consisting of a set of color matches using a particular system. Color matching performance was analyzed to yield measures of time, physical effort, accuracy, and convergence speed. The systems were then compared quantitatively according to these measures and qualitatively based on preference. The results indicate that the OPP color space led to greatest convergence and most user comfort, while the RGB space ranked second in terms of convergence, and the HSV space ranked second in terms of user comfort. Among the slider types, the dynamic sliders were superior according to almost every usability measure, followed by the static sliders and then the plain sliders. Context had a mixed effect in that the achromatic background led to slower but more accurate matches than did the chromatic background.
Perception Based Character Modeling and Animation
(Texas A&M University, 1999-12) Higa, Mitsutoshi; Tassinary, Louis G.; Akleman, Ergun; Graziano, William
This thesis explores how humans identify sex (male or female) and judge gender (masculine or feminine) and attractiveness of a computer animated walker. Hip and shoulder movements during the walk cycle and waist-to-hip ratio (WHR) of the walking figure were systematically manipulated to construct the stimulus set. The analysis of the experiment data suggested that perceived sex is identified primarily by WHR. Perceived gender and attractiveness are judged by both WHR and walk motion independently and interactively. These results were used to develop guidelines to reproduce and control perceived sex and gender for computer animated models.
Estimating the effect of future oil prices on petroleum engineering project investment yardsticks.
(Texas A&M University, 2004-09-30) Mendjoge, Ashish V; Lee, W. J.; Gaspar, Julian; McVay, Duane A.; Datta-Gupta, Akhil
This study proposes two methods, (1) a probabilistic method based on historical oil prices and (2) a method based on Gaussian simulation, to model future prices of oil. With these methods to model future oil prices, we can calculate the ranges of uncertainty in traditional probability indicators based on cash flow analysis, such as net present values, net present value to investment ratio and internal rate of return. We found that conventional methods used to quantify uncertainty which use high, low and base prices produce uncertainty ranges far narrower than those observed historically. These methods fail because they do not capture the "shocks" in oil prices that arise from geopolitical events or supply-demand imbalances. Quantifying uncertainty is becoming increasingly important in the petroleum industry as many current investment opportunities in reservoir development require large investments, many in harsh exploration environments, with intensive technology requirements. Insight into the range of uncertainty, particularly for downside, may influence our investment decision in these difficult areas.
Assessment of uranium-free nitride fuels for spent fuel transmutation in fast reactor systems
(Texas A&M University, 2004-09-30) Szakaly, Frank Joseph; Peddicord, Kenneth L.; Adams, Marvin L.; Hartwig, K. Ted
The purpose of this work is to investigate the implementation of nitride fuels containing little or no uranium in a fast-spectrum nuclear reactor to reduce the amount of plutonium and minor actinides in spent nuclear fuel destined for the Yucca Mountain Repository. A two tier recycling strategy is proposed. Thermal spectrum transmutation systems converted from the existing LWR fleet were modeled for the first tier, and the Japanese fast reactor MONJU was used for the fast-spectrum transmutation. The modeling was performed with the Monteburns code. Transmutation performance was investigated as well as delayed neutron fraction, heat generation rates, and radioactivity of the spent material in the short and long term for the different transmutation fuel cycles. A two-tier recycling strategy incorporating fast and thermal transmutation with uranium-free nitride fuel was shown to reduce the long-term heat generation rates and radioactivity of the spent nuclear fuel inventory.
Near real-time runoff estimation using spatially distributed radar rainfall data
(Texas A&M University, 2004-09-30) Hadley, Jennifer Lyn; Srinivasan, Raghavan; Wu, X. Ben; Knight, Robert
The purpose of this study was to evaluate variations of the Natural Resources Conservation Service (NRCS) curve number (CN) method for estimating near real-time runoff for naturalized flow, using high resolution radar rainfall data for watersheds in various agro-climatic regions of Texas. The CN method is an empirical method for calculating surface runoff which has been tested on various systems over a period of several years. Many of the findings of previous studies indicate the need to develop variations of this method to account for regional and seasonal changes in weather patterns and land cover that might affect runoff. This study seeks to address these issues, as well as the inherent spatial variability of rainfall, in order to develop a means of predicting runoff in near real-time for water resource management. In the past, raingauge networks have provided data for hydrologic models. However, these networks are generally unable to provide data in real-time or capture the spatial variability associated with rainfall. Radar networks, such as the Next Generation Weather Radar (NEXRAD) of the National Weather Service (NWS), which are widely available and continue to improve in quality and resolution, can accomplish these tasks. In general, a statistical comparison of the raingauge and NEXRAD data, where both were available, shows that the radar data is as representative of observed rainfall as raingauge data. In this study, watersheds of mostly homogenous land cover and naturalized flow were used as study areas. Findings indicate that the use of a dry antecedent moisture condition CN value and an initial abstraction (Ia) coefficient of 0.1 produced statistically significant results for eight out of the ten watersheds tested. The urban watershed used in this study produced more significant results with the use of the traditional 0.2 Ia coefficient. The predicted results before and during the growing season, in general, more closely agreed with the observed runoff than those after the growing season. The overall results can be further improved by altering the CN values to account for seasonal vegetation changes, conducting field verification of land cover condition, and using bias-corrected NEXRAD rainfall data.
Infants' use of luminance information in object individuation
(Texas A&M University, 2004-09-30) Woods, Rebecca Jindalee; Wilcox, Teresa; Bortfeld, Heather; Gabbard, Carl
Recent research suggests that by 4 months of age infants are able to individuate objects using form features, such as shape and size, but surface features, such as pattern and color, are not used until later in the first year (Wilcox, 1999). The current study sought to investigate two possible explanations for this developmental hierarchy. The visual maturation hypothesis suggests that the order in which infants use features to individuate objects corresponds to the order in which they are most readily processed by the developing visual system. A second hypothesis, the information processing biases hypothesis, suggests that infants are biased to attend to form features because form features provide information that is relevant to reasoning about object interactions. One way to test these hypotheses is to investigate infants' ability to individuate objects based on luminance. Luminance is detected at birth, so, according to the visual maturation hypothesis, luminance, like shape and size, will be used to individuate objects early in the first year. However, luminance is a surface property, so according to the information processing biases hypothesis, luminance, like pattern and color, will be used to individuate objects late in the first year. In the current study, 7-month-old (Experiment 1) and 11-month-old (Experiment 2) infants' use of luminance information in an object individuation task was investigated. The narrow-screen event-monitoring paradigm developed by Wilcox and Baillargeon (1998a) was used. Infants saw an event in which a ball moved behind a screen and a second ball emerged from behind the opposite edge of the screen. In one condition, the balls were identical, suggesting the presence of one object (same-luminance condition), and in another condition, the balls differed in luminance, suggesting the presence of two objects (different-luminance condition). The screen was either too narrow (narrow-screen event) or sufficiently wide (wide-screen event) to occlude two objects simultaneously. Seven-month-olds looked equally at each event, whereas 11.5-month-old's looked longer at the narrow-screen event in the different-luminance condition. These results suggest that 11.5-month-olds, but not 7.5-month-olds used luminance information to conclude that two distinct objects were involved in the event, thus supporting the information processing biases hypothesis.
The cost-effectiveness of retrofitting sanitary fixtures in restrooms of a university building
(Texas A&M University, 2004-09-30) Hwang, Byoung Hoon; Woods, Paul K.; Speed, F. Michael; Choudhury, Ifte M.
This study measured the actual water consumption of sanitary fixtures installed in restrooms of a university building while most studies have been based on the manufacturer's reported flow rate. Furthermore, this study analyzed the appropriateness of retrofitting with low-consumption water closets and urinals based on the actual water consumption. The purpose of this study is to analyze the cost-effectiveness of water savings from retrofitting water closets and urinals in restrooms of the Langford Architecture building A at Texas A&M University. The researcher directly measured the actual water-volume per flush of as-is, tune-up, low-consumption manual, and low-consumption automatic water closets and urinals. The data collected by these observations was analyzed, and the researcher evaluated the water savings of retrofitting water closets and urinals. Finally, this study provides the actual water-consumption data of sanitary fixtures and proves that retrofitting with low-consumption fixtures can save on water costs. The results will present practical standards to facility managers and other building professionals and will also contribute to determining the feasibility of retrofitting water closets and urinals.
Construction and characterization of yciGFE mutants in Escherichia coli
(Texas A&M University, 2004-09-30) Kalyanaraman, Gayathri; Siegele, Deborah A.; Bell-Pedersen, Deborah; Polymenis, Michael S.
Escherichia coli has served as a model organism for studies in molecular genetics and physiology since the 1960s. Yet the function of 20% of the 4288 known and predicted proteins in E. coli is still not known. Almost two-thirds of these proteins have homologs in other microorganisms, but their function(s) is not known in any organism. One such protein is YciG. YciG was chosen as the focus of this study because, intriguingly, an ortholog of YciG is found in the genome of the fungus Neurospora crassa. The gene encoding YciG is predicted to be in an operon with two other genes, yciF and yciE. Genes in the same operon often encode proteins with related functions, so the study was extended to include YciF and YciE. To determine the function of these proteins, in-frame deletion alleles were constructed and strains lacking one or more of the three proteins were tested for mutant phenotypes. Expression of the yciGFE operon is induced by several stresses and is regulated by RpoS, which controls the general stress response in E. coli. Therefore, we tested the ability of the mutant strains to survive environmental stresses. Our results revealed that YciG was important for stationary-phase resistance to thermal stress, oxidative stress and, in particular, acid stress. Both RpoS-dependent and RpoS-independent acid resistance mechanisms are found in E. coli. YciG was shown to be required for RpoS-independent acid resistance, but further experiments are needed to determine whether YciG also is required for RpoS-dependent acid resistance. YciG was not required for normal exponential growth of E. coli, as mutants lacking YciG had the same growth rate as the wild-type parent. No mutant phenotypes have been found yet for mutants lacking YciF or YciE. yciE deletion mutants showed the same growth rate and the same level of acid resistance as wild-type cells. The acid resistance of yciF mutants has not yet been tested, and strains lacking YciE and/or YciF need to be assayed for their ability to survive stresses other than acid stress.
Endogenous variables and weak instruments in cross-sectional nutrient demand and health information analysis: a comparison of solutions
(Texas A&M University, 2004-09-30) Bakhtavoryan, Rafael Gagik; Davis, George C.; McIntosh, W. Alex; Nichols, John P.
In recent years, increasing attention has turned toward the effect of health information or health knowledge on nutrient intake. In determining the effect of health information on nutrient demand, researchers face the estimation problem of dealing with the endogeneity of health information knowledge. The standard approach for dealing with this problem is an instrumental variables (IV) procedure. Unfortunately, recent research has demonstrated that the IV procedure may not be reliable in the types of data sets that contain health information and nutrient intakes because the instruments are not sufficiently correlated with the endogenous variables (i.e., instruments are weak). This thesis compares the reliability of the IV procedure (and the Hausman test) with a relatively new procedure, directed graphs, given weak instruments. The goal is to determine if the method of directed graphs performs better in identifying an endogenous variable and also relevant instruments. The performance of the Hausman test and directed graphs are first assessed through conducting a Monte-Carlo sampling experiment containing weak instruments. Because the structure of the model is known in the Monte-Carlo experiment, these results are used as a guideline to determine which procedure would be more reliable in a real world setting. The procedures are then applied to a real-world cross-sectional dataset on nutrient intake. This thesis provides empirical evidence that neither the IV estimator (and Hausman test) or the directed graphs are reliable when instruments are weak, as in a cross-sectional dataset.
Selected construction contract administration standard operation procedures for Texas Department of Transportation, Odessa District
(Texas A&M University, 2004-09-30) Reachi, Santiago; Maxwell, Donald A.; Holland, Charles D.; Anderson, Stuart D.; Smith, Donald R.
In order to achieve the stated goal of reducing the final closing procedure time cycle for construction projects at the Texas Department of Transportation (TxDOT) Odessa District, several standard operating procedures (SOPs) for project construction control and management had to be revised. Seemingly unrelated tasks created posterior chains of events that resulted in bottlenecks in the process and delayed final project closing. Four specific SOPs were identified and analyzed to determine which tasks required modification and what was expected from these modifications. A mission for each specified SOP was conceived and written to give a clear view of the intent of the procedure. Afterwards, district policies were drafted to provide the means to fulfill the intent. The procedural changes, compatible with TxDOT statewide procedures, allowed the time spent in the processes to remain the same but redistributed it to reduce the end-loading of the control process. The new SOPs require an even time distribution cyclically throughout the project. Control procedures are done only once, shortening the final closing procedure for projects by doing one-time, short, cyclical, consecutive control tasks of the same procedure throughout the life of the project, rather than doing some of them once cyclically and then again at the closing procedure and others just at the closing procedure. These changes resulted in a shorter end-cycle time, which substantially reduced the final closing procedure time for each project, without affecting the integrity and safeguards of the project. The changes resulted in more efficient and timely financial, managerial, and engineering control of projects. The procedures revised were (1) Review and Approval of Change Orders; (2) Review and Approval of Monthly Progress Estimates; (3) Review and Approval of Interim and Final Audits and Final Estimate; and (4) Storm Water Pollution Prevention Plans (SW3P) Records Management and Auditing Procedures.
A design approach to a risk review for fuel cell-based distributed cogeneration systems
(Texas A&M University, 2004-09-30) Luthringer, Kristin Lyn; Lalk, Thomas; Appleby, John; Schneider, William; Koppa, Rodger
A risk review of a fuel cell-based distributed co-generation (FC-Based DCG) system was conducted to identify and quantify the major technological system risks in a worst-case scenario. A risk review entails both a risk assessment and a risk analysis of a designed system, and it is part of risk engineering. Thorough literature reviews and expert interviews were conducted in the field of fuel cells. A thorough literature review of the risk engineering field was also conducted. A procedure for a risk review of the FC-Based DCG System was developed. The representative system design was identified by the current DCG design technology. The risk assessment was carried out, identifying the system components and potential failure modes and consequences. Then, using probabilities of failure for the various system components, the risk associated with a particular system design was determined. A Monte Carlo simulation on the total system reliability was used to evaluate the potential for system failure at a time of 1 hour, 5 hours, 10 hours, 50 hours, 100 hours and 500 hours of continuous operation. The original system was found to be acceptable at the initial times, but after 100 hours was predicted to fail. The components which consistently contribute significantly to the overall system risk are the membrane electrode assembly (MEA) and the nickel-metal foam flow fields. A revised system was analyzed with the reliability of the MEA and the Ni-foam set to 100%. After the revision, the components which contributed significantly to the system risk were the pumps. Simulations were run for several alternative systems to provide feedback on risk management suggestions. The risk engineering process developed with the design approach for this research is applicable to any system and it accommodates the use of many different risk engineering tools.
Remote sensing for site-specific management of biotic and abiotic stress in cotton
(Texas A&M University, 2004-09-30) Falkenberg, Nyland Ray; Piccinni, Giovanni; Cothren, J. T.; Leskovar, Daniel I.; Rush, Charlie M.
This study evaluated the applicability of remote sensing instrumentation for site- specific management of abiotic and biotic stress on cotton grown under a center pivot. Three different irrigation regimes (100%, 75%, and 50% ETc) were imposed on a cotton field to 1) monitor canopy temperatures of cotton with infrared thermometers (IRTs) in order to pinpoint areas of biotic and abiotic stress, 2) compare aerial infrared photography to IRTs mounted on center pivots to correlate areas of biotic and abiotic stress, and 3) relate yield to canopy temperatures. Pivot-mounted IRTs and IR camera were able to differentiate water stress between the irrigation regimes, however, only the IR camera was effectively able to distinguish between biotic (cotton root rot) and abiotic (drought) stress with the assistance of groundtruthing. The 50% ETc regime had significantly higher canopy temperatures, which were reflected in significantly lower lint yields when compared to the 75% and 100% ETc regimes. Deficit irrigation up to 75% ETc had no impact on yield, indicating that water savings were possible without yield depletion.
Associative tolerance to nicotine's analgesic effects: studies on number of conditioning trials and corticosterone
(Texas A&M University, 2004-09-30) Davis, Kristina; Cepeda-Benito, Antonio; Wellman, Paul; Champney, Thomas
This study examined the number of conditioning trials necessary to produce associative nicotine tolerance and the changes in corticosterone levels during the procedures. Six independent groups of rats (N = 355) were run through tolerance acquisition procedures for 1, 5, or 10 conditioning sessions. Treatment groups were comprised of animals that received nicotine-environment pairings, animals that received nicotine explicitly unpaired with the drug administration environment, and control groups that received either saline throughout or no treatment. Three of the groups were tested for nicotine-induced analgesia using the tail-flick and hot-plate assays, and three groups were blood sampled after either nicotine or saline injection. Pairing of environment with nicotine produced greater tolerance for rats after 5 conditioning sessions in the tail flick and after 10 conditioning sessions in the hot-plate. Corticosterone levels were elevated in all rats given nicotine. Rats that received the nicotine-environment pairing showed a conditioned release of corticosterone in response the environment after both 5 and 10 conditioning sessions.
Selective catalytic reduction (SCR) of nitric oxide (NO) with ammonia over vanadia-based and pillared interlayer clay-based catalysts
(Texas A&M University, 2004-09-30) Oh, Hyuk Jin; Caton, Jerald A.; Annamalai, Kalyan; Anthony, Rayford G.
The selective catalytic reduction (SCR) of nitric oxide (NO) with ammonia over vanadia-based (V2O5-WO3/TiO2) and pillared interlayer clay-based (V2O5/Ti-PILC) monolithic honeycomb catalysts using a laboratory laminar-flow reactor was investigated. The experiments used a number of gas compositions to simulate different combustion gases. A Fourier transform infrared (FTIR) spectrometer was used to determine the concentrations of the product species. The major products were nitric oxide (NO), ammonia (NH3), nitrous oxide (N2O), and nitrogen dioxide (NO2). The aim was to delineate the effect of various parameters including reaction temperature, oxygen concentration, NH3-to-NO ratio, space velocity, heating area, catalyst arrangement, and vanadium coating on the removal of nitric oxide. The investigation showed that the change of the parameters significantly affected the removals of NO and NH3 species, the residual NH3 concentration (or NH3 slip), the temperature of the maximum NO reduction, and the temperature of complete NH3 conversion. The reaction temperature was increased from the ambient temperature (25°C) to 450 °C. For both catalysts, high NO and NH3 removals were obtained in the presence of a small amount of oxygen, but no significant influence was observed from 0.1 to 3.0% O2. An increase in NH3-to-NO ratio increased NO reduction but decreased NH3 conversions. For V2O5-WO3/TiO2, the decrease of space velocity increased NO and NH3 removals and broadened the active temperature window (based on NO > 88% and NH3 > 87%) about 50°C. An increase in heating area decreased the reaction temperature of the maximum NO reduction from 350 to 300°C, and caused the active reaction temperature window (between 250 and 400°C) to shift toward 50°C lower reaction temperatures (between 200 and 350°C). The change of catalyst arrangements resulted slight improvement for NO and NH3 removals, therefore, the change might contribute to more gas removals. The catalyst with extra vanadium coating showed higher NO reductions and NH3 conversions than the catalyst without the extra vanadium coating.
A Study of Heat Pump Fin Staged Evaporators Under Frosting Conditions
(Texas A&M University, 2004-09-30) Yang, Jianxin; O'Neal, Dennis L.; Anand, Nagamangala K.; Annamalai, Kalyan; Holtzapple, Mark T.
This dissertation provides a detailed description of the research work completed on fin staged heat exchangers. The effects of staging fin on the frosting performance of heat pump evaporators and the whole heat pump system have been studied experimentally and theoretically. Frost degrades the performance of fin-and-tube outdoor coils as well as the whole heat pump system. The objective of the experimental part of this study was to investigate the effects of the staging fin on the frost/defrost performance of heat pump outdoor coils under different operating conditions. To accomplish this objective, a series of frosting tests was conducted on an off-the-shelf heat pump system with five (three two-row and two three-row) evaporators over a range of outdoor temperatures and humidities and a range of airflow rates typical of those found in residential sized heat pumps. Performances of the heat pump unit with baseline or fin staged outdoor coils at either frosting or steady-state test conditions are compared and analyzed. Experimental data showed that for a given tworow heat pump outdoor coil operating at the standard ANSI/ASHRAE 35 °F (1.7 °C) frosting conditions, fin staging increased cycle time and COP. There was a small decrease in peak capacity at lower initial airflow rates. At a lower temperature of 28 °F (2.2 °C), cycle time continued to be enhanced with fin staging, and cyclic COP was within 5% of the base case when fin staging was used. In the second step of this work, an analytical model to simulate the performance of both the baseline and fin staged heat pump coils under frosting conditions was developed based on fundamental heat and mass transfer principles. The transient performance of the frosted evaporator was analyzed with the quasi-steady state approach. The section-by-section evaluation scheme was combined with the tubeby- tube approach to model the mass transfer process in the frost formation module. The two-dimensional fin surface was divided into a number of parallel non-overlapping sections. Each of the sections was the calculation unit for the mass transfer. Methods for calculating the airside heat transfer coefficient and friction factor were developed and applied to the simulation model of the fin staged coil. To verify the validity of the frosted evaporator model, the frosting performance of three two-row coils at the same test conditions was simulated and compared with experimental data. The frosted evaporator model appeared to provide satisfactory simulation of the fin-and-tube heat exchanger during the frost buildup process. Comparisons with the test data indicated that the model could capture the trends of the coil capacity, pressure drop, airflow and frost growth. The model also provided a variety of other simulation results including frost mass accumulation, air velocity inside coil, air and refrigerant outlet state, and so on. Overall, the numerical results were in reasonable agreement with the test data under different frosting operation conditions.
Estimating uncertainties in integrated reservoir studies
(Texas A&M University, 2004-09-30) Zhang, Guohong; McVay, Duane A.; Lee, William J.; Watkins, Joel S.; Ayers, Walter B.
To make sound investment decisions, decision makers need accurate estimates of the uncertainties present in forecasts of reservoir performance. In this work I propose a method, the integrated mismatch method, that incorporates the misfit in the history match into the estimation of uncertainty in the prediction. I applied the integrated mismatch method, which overcomes some deficiencies of existing methods, to uncertainty estimation in two reservoir studies and compared results to estimations from existing methods. The integrated mismatch method tends to generate smaller ranges of uncertainty than many existing methods. When starting from nonoptimal reservoir models, in some cases the integrated mismatch method is able to bracket the true reserves value while other methods fail to bracket it. The results show that even starting from a nonoptimal reservoir model, but as long as the experimental designs encompass the true case parameters, the integrated mismatch method brackets the true reserves value. If the experimental designs do not encompass all the true case parameters, but the true reserves value is covered by the experiments, the integrated mismatch method may still bracket the true case. This applies if there is a strong correlation between mismatch and closeness to the true reserves value. The integrated mismatch method does not need a large number of simulation runs for the uncertainty analysis, while some other methods need hundreds of runs.
A new approach for fast potential evaluation in N-body problems
(Texas A&M University, 2004-09-30) Juttu, Sreekanth; Sarin, Vivek; Shi, Weiping; Nelson, Paul
Fast algorithms for potential evaluation in N-body problems often tend to be extremely abstract and complex. This thesis presents a simple, hierarchical approach to solving the potential evaluation problem in O(n) time. The approach is developed in the field of electrostatics and can be extended to N-body problems in general. Herein, the potential vector is expressed as a product of the potential matrix and the charge vector. The potential matrix itself is a product of component matrices. The potential function satisfies the Laplace equation and is hence expressed as a linear combination of spherical harmonics, which form the general solutions of the Laplace equation. The orthogonality of the spherical harmonics is exploited to reduce execution time. The duality of the various lists in the algorithm is used to reduce storage and computational complexity. A smart tree-construction strategy leads to efficient parallelism at computation intensive stages of the algorithm. The computational complexity of the algorithm is better than that of the Fast Multipole Algorithm, which is one of the fastest contemporary algorithms to solve the potential evaluation problem. Experimental results show that accuracy of the algorithm is comparable to that of the Fast Multipole Algorithm. However, this approach uses some implementation principles from the Fast Multipole Algorithm. Parallel efficiency and scalability of the algorithms are studied by the experiments on IBM p690 multiprocessors.
Phophorus and nitrogen leaching losses during turf establishment
(Texas A&M University, 2004-09-30) Hay, Francis John; Vietor, Donald; Zuberer, David; Munster, Clyde
Concerns over water quality have led to required removal of 50 % of dairy manure phosphorus (P) from the impaired Bosque River Watershed. Application of composted dairy manure (CDM) to sod and moving P off the watershed with sod has prompted a study using box lysimeters to determine NO3--N and P leaching from transplanted sod grown with CDM and inorganic fertilizer as well as sprigs top-dressed with CDM. Treatments were applied to lysimeters filled with a silica sand medium. Three leaching events were imposed, leaching 0.07 to 0.09 % of the total P applied and 0.09 to 1.43 % of total N applied. Concentrations of P in leachate averaged 0.04 to 0.25 mg L-1. Top-dressed CDM on sprigs leached statistically greater amounts of NO3--N than both transplanted sod treatments and greater P than the fertilizer grown sod. After the third leaching event, all treatments received an additional application of P, 100 kg ha-1 as CDM for manure-grown sod and sprigs, 50 kg ha-1 as triple superphosphate for fertilizer-grown sod. An additional three leachings were imposed. Top-dressed sprigs and transplanted sod leached similar amounts of P following the additional P application. Applied nutrients appeared to stay mainly in the sod layer and in the sand medium just below the sod layer. Top-dressed CDM appears to exhibit greater leaching losses of NO3--N than transplanted manure-grown sod and greater N and P losses than transplanted fertilizer grown sod.
Measuring the impact of technology on leadership education
(Texas A&M University, 2004-09-30) Jones, Robert T.; Townsend, Christine D.; Briers, Gary E.; Korhonen, Lloyd J.
The purposes of this study were to determine the effectiveness of a computer-assisted lab environment in a course on leadership and to determine if undergraduate students believe that leadership concepts can be successfully taught in an asynchronous environment, in this case, using the technology of the world wide web. Students' attitudes toward computer-based leadership education were measured by a leadership perception index, a technology perception index, a class-inclusion acceptance index, and a discussion technology acceptance index administered through a post-activity survey that measured their responses in both a quantitative and qualitative format. Students participated in a leadership lab activity in one of three treatments: 1) no computer-facilitated interaction and traditional classroom interaction, 2) completely asynchronous, computer-facilitated interaction, or 3) hybrid interaction consisting of half computer-facilitated, and half traditional classroom interaction. A post-activity survey was used to collect data about the students' perceptions of their experiences. Post-activity survey scores indicated that a majority of students accept learning about leadership through asynchronous technological means such as the world wide web. Students who were not exposed to any technological experience in this activity quantitatively answered that the interpolation of technology into leadership education would not be successful. The hybrid group quantitatively felt the use of technology was most acceptable of the three treatment groups, with slightly fewer "positive" results from the completely asynchronous, solely computer-facilitated group. Students had a positive attitude toward computers, and qualitatively identified the need to use computers more prevalently in undergraduate teaching. Students' qualitative results also indicated that students felt that computers were important to their future and most seemed to enjoy to opportunity to complete a lab using them. Since the computer facilitated assignment was completed using the Internet as a connection medium, additional data were collected from students. Interestingly, of students involved in the asynchronous section, only 18% completed their assignments during morning hours (from 6:00 a.m. to noon), while 39% completed their assignments between 8:30 p.m. and 1:00 a.m.

Browse

Browsing Electronic Theses, Dissertations, and Records of Study (2002– ) by Issue Date

Results Per Page

Sort Options