Texas A&M University at College Station

Permanent URI for this collectionhttps://hdl.handle.net/2249.1/23606

Texas A&M University is a land-grant, sea-grant and space-grant institution located in College Station, Texas. The university’s enrollment includes approximately 44,000 students studying for degrees in 10 academic colleges. This collection contains the theses and dissertations produced at A&M since 2002.

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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
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
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
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.
A model for the development of a lobate alpine rock glacier in southwest Colorado, USA: implications for water on Mars
(Texas A&M University, 2004-09-30) Degenhardt, John Jerome
Rock glaciers play a significant role in the alpine debris transport system. For practical and engineering considerations, identifying the internal structure and its relationship to surface characteristics is significant in terms of how a rock glacier settles during periods of melting, and the mode of deformation. A better understanding of these factors is important for engineers, engineering geologists and geomorphologists who must make prudent evaluations of rock glaciers as potential sites for human development and uses. It is equally important for evaluating potential stores for water on other planets such as Mars. Ground penetrating radar (GPR) shows that the internal structure of a lobate rock glacier located in the San Juan Mountains of southwest Colorado consists of continuous to semi-continuous horizontal layers of ice-supersaturated sediments and coarse blocky rockslide debris which likely formed through catastrophic episodes of rockfall from the cirque headwall. Folds in the uppermost layers correspond to the surface expression of ridges and furrows, indicating that compressive stresses originating in the steep accumulation zone are transmitted downslope through the rock glacier. The rock glacier is a composite feature that formed by a process involving the development and overlap of discrete flow lobes that have overridden older glacial moraine and protalus rampart materials. The latter materials have been incorporated into the present flow structure of the rock glacier. The discovery of rock glacier-like features on Mars suggests the presence of flowing, or once-flowing ice-rock mixtures. These landforms, which include lobate debris aprons, concentric crater fill and lineated valley fill, hold significant promise as reservoirs of stored water ice that could be used as fuel sources for human exploration of Mars and provide a frozen record of the climatic history of the planet. To this end, the rock glacier in this study was used as a surrogate for similar Martian landforms. Liquid water, found to be abundant in this rock glacier, occurs within a network of interconnected channels that permeate throughout the landform. In terms of water storage within Martian analogs, consideration must include the possibility that some water ice may be stored in relatively pure form within lenses and vein networks that are supplied by seasonal frost accumulation and/or water influx from below.
Flight characteristics of pen-reared and wild prairie-chickens and an evaluation of a greenhouse to rear prairie-chickens
(Texas A&M University, 2004-09-30) Hess, Marc Frederick
The introduction of pen-reared Attwater's prairie-chickens (APC, Tympanuchus cupido attwateri) into the wild to supplement existing populations has met with marginal success. Flight characteristics, predator avoidance behavior, and rearing methods are possible factors contributing to post-release mortality of pen-reared birds. To evaluate flight characteristics and predator avoidance behavior of pen-reared APC's released onto the Attwater Prairie Chicken National Wildlife Refuge, flight characteristics and predator avoidance behavior of pen-reared APC's was compared to wild greater prairie-chickens (GPC, T. c. pinnatus) in Minnesota and Kansas using a radar gun and a trained dog. There was no difference (P = 0.134) in flight speed for pen-reared APC and wild GPC. However, wild GPC had greater (P < 0.001) flight distances than did pen-reared APC. Wild GPC and pen-reared APC that had survived in the wild for at least a year flushed at a greater (P < 0.001) distance from an approaching human than did pen-reared APC that had been released for less than 3 months. A trained dog was able to approach closer (P < 0.001) to APC than GPC before birds flushed, and APC did not fly as far as GPC after being flushed by the dog. Pen-reared APC displayed flight endurance deficiencies and were more approachable by humans and a dog before they flushed when compared to wild GPC, which could explain their increased mortality when released into the wild. To determine if APC chicks could be reared without daily human contact, pelleted food, and water in founts, a greenhouse was used to rear chicks in a semi-natural environment. Planted vegetation and commercial insects provided hiding cover and a food source for the APC chicks. An underground heat source provided chick warmth, and water misters and a sprinkler system simulated dew (a water source for chicks) and rain. The greenhouse provided chicks protection from predators and adverse weather conditions (before they could thermo-regulate) while exposing chicks to natural sunlight, day length, and temperature fluctuations. This technique allowed chicks to be reared in a semi-natural environment which reinforced their natural foraging behavior for food and water, and reinforced their hiding and avoidance behaviors, creating a wilder pen-reared bird.
Sharing of figurative language themes in expert therapy: occurrence and effect on client experiencing and therapeutic bond
(Texas A&M University, 2004-09-30) Cardin, Scott Ashley
The purpose of this study was to examine the use and effect of figurative language discourse in examples of expert therapy. More specifically, one of the main reasons for conducting this study was to describe figurative language discourse, its production, use, and potential effects on the therapeutic relationship and client experiencing. Training videos were selected and transcribed using criteria for selection of examples of expert therapy. Fifty-six excerpts, each two-minutes in length, were taken from the transcribed therapy sessions and used for the analyses. One set of raters was trained to identify instances of figurative language and make ratings of shared theme. Another set of raters was trained to use the Experiencing Scales and the Working Alliance Inventory on the transcribed excerpts. Analyses were conducted to investigate the frequency of use and relationship between therapist and client figurative language dialogue. Results indicated that the majority of figurative language used in examples of expert therapy is metaphoric in nature. Additionally, it was found that the majority of figures of speech were frozen in meaning or were commonly used. A small percentage of figures of speech were shared conceptually between the therapist and the client. Regarding the shared figurative language, a statistically significant difference between therapists and clients with regard to their production of shared figurative language was found and indicates that use of shared figurative language by expert therapists may be a subtle and indirect way in which therapeutic alliance is initially established as well as maintained. It may also represent how expert therapists follow content of the therapy session. In addition, a regression analysis conducted to determine if there is a relationship between shared figurative language and ratings of therapeutic alliance did not meet statistical significance. Overall, the results of this study provide preliminary findings with regard to what type of figures of speech expert therapists use and give a clear direction in terms of the next direction for research. Additionally, this experiment provides direction for the type of methodology that should be utilized in future research.
College students' comfort with assertive behaviors: An analysis of students with and without disabilities in three different postsecondary institutions
(Texas A&M University, 2004-09-30) Orr, Kristie Scrutchfield
First-year college students have many new responsibilities and challenges. They are faced with increasing autonomy and must find resources and people to help guide them. Students with disabilities face an even greater need to be independent and juggle more responsibilities, as they must disclose their disabilities to campus personnel if they need accommodations and become a self-advocate. In order to self-advocate, students must feel comfortable with being assertive. This study examined the differences in comfort with assertive behaviors between students with and without disabilities at three different types of postsecondary institutions (junior college, 4-year regional university, and 4-year Research 1 university). Two hundred seventy-eight freshman and sophomore students completed a questionnaire concerning their comfort with many different assertive behaviors. The following three variables were examined: a) college students' comfort with overall assertiveness; b) college students' comfort with verbal assertiveness; and c) college students' comfort with prosocial verbal skills. iv There were no significant differences between students with disabilities and students without disabilities in terms of their discomfort with assertive behaviors on any of the three variables. Males were more comfortable with assertive behaviors than females in terms of their overall assertiveness and their verbal assertiveness. Students from the 2-year junior college were more comfortable with overall assertiveness and verbal assertiveness than students at either the 4-year regional university or the 4-year Research 1 university. There were no differences between groups in terms of their prosocial verbal skills. Conclusions about the differences found in the study are reported. Recommendations for disability service providers are provided, as well as suggestions for future research.
Human skeletal remains of the ancient Maya in the caves of Dos Pilas, Guatemala
(Texas A&M University, 2004-09-30) Minjares, Amador, Jr.
This study focuses on the assessment of the depositional activity that occurred in six caves of the Petexbatun region of the Peten, Guatemala through a quantitative analysis of the human skeletal material recovered from them. Five of these caves are associated with the site of Dos Pilas; the sixth cave (Cueva de Los Quetzales) is located beneath the site of Las Pacayas. The cave is an important aspect of the Maya worldview, as evidenced in the artifactual and skeletal material found in caves by archaeological exploration. My study is specifically focused on the assessment of the primary and/or secondary burial of Maya dead within these caves via analyses of the relative skeletal element frequencies, the minimum and probable number of individuals, and the identification of human cut marks. Based on these lines of evidence and data from preliminary reports, between 100 and 150 individuals of both sexes and various age groups were primarily deposited/buried in these caves. Secondary activity may be inferred based on evidence of human-made cut marks on several elements. There is no osteological evidence to support the hypothesis of human sacrifice. I was unable to determine the status of the individuals deposited in the caves. The best interpretation is that several types of depositional activity occurred within these caves over time.
Impact of the red imported fire ant upon cotton arthropods
(Texas A&M University, 2004-09-30) Diaz Galarraga, Rodrigo Rogelio
Inclusion/exclusion field experiments demonstrated that the red imported fire ant, Solenopsis invicta Buren, did not affect the abundance of 49 groups of insects and spiders collected in pitfall traps. However, arthropod diversity was significantly greater (H' = 2.829) in exclusion plots relative to inclusion plots (H' = 2.763). Moreover, this study demonstrated that S. invicta can have an important impact upon cotton arthropod communities, including key predator species. Densities of ground beetles (Carabidae), spiders, lacewings (Chrysoperla spp.), and minute pirate bugs (Orius spp.) were significantly lower in the presence of S. invicta. However, populations of aphidophagous insects such as Hippodamia spp. and Scymnus spp. increased with cotton aphid (Aphis gossypii Glover) density early in the season. Abundance of cotton aphids was ca. 5x greater in inclusion plots, likely due to protection and tending by S. invicta. This increase was observed early in the season, though aphid populations did not reach economic levels. Predation of sentinel bollworm [Helicoverpa zea (Boddie)] and beet armyworm (Spodoptera exigua Hubner) eggs increased 20-30%, when S. invicta was present. Most predation of sentinel beet armyworm egg masses, measured via direct nocturnal observations, was due to S. invicta (68%) and cotton fleahopper [Pseudatomoscelis seriatus (Reuter)] (21%) in plots with S. invicta, and by the mite Abrolophus sp. (52%), spiders (13%) and minute pirate bug (13%) in plots without S. invicta. The frequencies of minute pirate bug, cotton fleahopper, S. invicta and native ants in beat bucket samples did not accurately reflect the frequency with which they were observed feeding on sentinel noctuid eggs. Overall, the results of these studies demonstrated that S. invicta was associated with declines in the abundances of minute pirate bug, spiders, and lacewing and with an increment in cotton aphid populations, though they did not reach the economic threshold. Moreover, S. invicta significantly increased predation of bollworm and beet armyworm eggs. All together, the results suggested that S. invicta has a net positive impact on cotton pest management.
Reservoir characterization using experimental design and response surface methodology
(Texas A&M University, 2004-09-30) Parikh, Harshal
This research combines a statistical tool called experimental design/response surface methodology with reservoir modeling and flow simulation for the purpose of reservoir characterization. Very often, it requires large number of reservoir simulation runs for identifying significant reservoir modeling parameters impacting flow response and for history matching. Experimental design/response surface (ED/RS) is a statistical technique, which allows a systematic approach for minimizing the number of simulation runs to meet the two objectives mentioned above. This methodology may be applied to synthetic and field cases using existing statistical software tools. The application of ED/RS methodology for the purpose of reservoir characterization has been applied for two different objectives. The first objective is to address the uncertainties in the identification of the location and transmissibility of flow barriers in a field in the Gulf of Mexico. This objective is achieved by setting up a simple full-factorial design. The range of transmissibility of the barriers is selected using a Latin Hypercube Sampling (LHS). An analysis of variance (ANOVA) gives the significance of the location and transmissibility of barriers and comparison with decline-type curve analysis which gives us the most likely scenarios of the location and transmissibility of the flow barriers. The second objective is to identify significant geologic parameters in object-based and pixel-based reservoir models. This study is applied on a synthetic fluvial reservoir, whose characteristic feature is the presence of sinuous sand filled channels within a background of floodplain shale. This particular study reveals the impact of uncertainty in the reservoir modeling parameters on the flow performance. Box-Behnken design is used in this study to reduce the number of simulation runs along with streamline simulation for flow modeling purposes. In the first study, we find a good match between field data and that predicted from streamline simulation based on the most likely scenario. This validates the use of ED to get the most likely scenario for the location and transmissibility of flow barriers. It can be concluded from the second study that ED/RS methodology is a powerful tool along with a fast streamline simulator to screen large number of reservoir model realizations for the purpose of studying the effect of uncertainty of geologic modeling parameters on reservoir flow behavior.
An analysis of selected pre- and post-admission variables as they relate to the retention of new freshmen at a large, research, public university
(Texas A&M University, 2004-09-30) Boyd, Kriss Hope
Texas A&M University changed the criteria for freshman admission after a legal decision in 1996 removed ethnicity from the list of possible admission criteria. The process now includes subjective criteria such as activities, leadership, service and awards as well as the traditional objective criteria such as test scores and rank in high school class. The purpose of this study was to analyze the relationship between some of the admission criteria and retention of freshmen from the first fall to the second fall. Retention of freshmen is a performance indicator for higher education in Texas. The results of the logistic regressions showed that the relationships were modest at best and had a very small pseudo r2. The objective criteria of test scores and high school rank were either not significant or did almost nothing to increase the odds ratio. The only variable that was significant in the regression, but had a modest odds ratio, across the regression for all students and for the regressions for the subgroups of female and male students, Anglo, Hispanic and Asian American students, and for students from targeted, disadvantaged high schools was parents' education level. The points assigned to students by admissions counselors for self-reported leadership activities were significant for the regressions for all students, for female students and for Anglo students, but did very little to increase the likelihood of retention. Test scores were significant in the regressions for all students, for female students and for Hispanic students, but did almost nothing to increase the likelihood of retention. None of the variables were significant in the regression for the small group of African American students. One conclusion from the analysis is that some students whose parents have the lowest levels of education and some students from targeted high schools have unmet needs that cause higher attrition rates for these groups. However, even within these groups, there are other factors driving the students' commitment to stay enrolled for the second year at the institution than those included in this study.
Approaches to test set generation using binary decision diagrams
(Texas A&M University, 2004-09-30) Wingfield, James
This research pursues the use of powerful BDD-based functional circuit analysis to evaluate some approaches to test set generation. Functional representations of the circuit allow the measurement of information about faults that is not directly available through circuit simulation methods, such as probability of random detection and test-space overlap between faults. I have created a software tool that performs experiments to make such measurements and augments existing test generation strategies with this new information. Using this tool, I explored the relationship of fault model difficulty to test set length through fortuitous detection, and I experimented with the application of function-based methods to help reconcile the traditionally opposed goals of making test sets that are both smaller and more effective.
Power supply partitioning for placement of built-in current sensors for IDDQ testing
(Texas A&M University, 2004-09-30) Prasad, Abhijit
IDDQ testing has been a very useful test screen for CMOS circuits. However, with each technology node the background leakage of chips is rapidly increasing. As a result it is becoming more difficult to distinguish between faulty and fault-free chips using IDDQ testing. Power supply partitioning has been proposed to increase test resolution by partitioning the power supply network, such that each partition has a relatively small defect-free IDDQ level. However, at present no practical partitioning strategy is available. The contribution of this thesis is to present a practical power supply partitioning strategy. We formulate various versions of the power supply partitioning problem that are likely to be of interest depending on the constraints of the chip design. Solutions to all the variants of the problem are presented. The basic idea behind all solutions is to abstract the power topology of the chip as a flow network. We then use flow techniques to find the min-cut of the transformed network to get solutions to our various problem formulations. Experimental results for benchmark circuits verify the feasibility of our solution methodology. The problem formulations will give complete flexibility to a test engineer to decide which factors cannot be compromised (e.g. area of BICS, test quality, etc) for a particular design and accordingly choose the appropriate problem formulation. The application of this work will be the first step in the placement of Built-In Current Sensors for IDDQ testing.
An AVO method toward direct detection of lithologies combining P-P and P-S reflection data
(Texas A&M University, 2004-09-30) Carcuz Jerez, Juan Ramon de Jesus
I here present a combined AVO analysis of P-P and P-S reflection data whose objective is to improve the identification of lithology by estimating the specific values of Poisson's ratio, [sigma], for each rock formation in a given geological model, rather than a contrast between formations. Limited knowledge on the elastic parameters of a given rock formation and difficulty regarding the availability and processing of P-S data constitute hindrances of lithology identification. Considering that ocean bottom seismology (OBS) has aided in solving the problem of P-S data availability, limited information on elastic parameters is still a challenge, and the focus of this thesis. The present analysis is based on Zoeppritz' solution for the P-P and P-S reflection coefficients, RPP and RPS, with a slight modification. We used the normalized P-S reflection coefficient; i.e., R'PS = RPS / sin [theta] for [theta] > 0, instead of RPS, where [theta] is the incident angle. By normalizing RPS, we avoid dealing with the absence of converted S-waves at small incident angles and enhance the similar linear behavior of the P-P and normalized P-S reflection coefficients at small angles of incidence. We have used the linearity of RPP and R'PS at angles smaller than 35 degrees to simultaneously estimate the average VP/VS ratio, the contrasts of P- and S-wave velocities, and the contrast of density. Using this information, we solve for Poisson's ratio of each formation, which may enable lithology discrimination. The feasibility of this analysis was demonstrated using nonlinear synthetic data (i.e., finite-difference data). The results in estimating Poisson's ratio yielded less than 5 percent error. We generalize this new combined P-P and P-S AVO analysis for dipping interfaces. Similarly to the nondipping interface case, our derivations show that the amplitude variation with offset (AVO) of P-P and P-S for a dipping interface can be cast into intercepts and gradients. However, these intercepts and gradients depend on the angle of the dipping interface. Therefore, we further generalize our analysis by including a migration step that allows us to find the dipping angle. Because seismic data is not available in terms of RPP and R'PS, this process includes recovery of reflection coefficients after migrating the data and correcting for geometrical spreading, as done by Ikelle et al. (1986 and 1988). The combination of all of these steps, namely geometrical-spreading correction, migration, and AVO analysis, is another novelty of this thesis, which leads to finding the specific values of Poisson's ratio of each rock formation directly from the seismic data.
The impact of parental involvement: a study of the relationship between homework and kindergarten Texas Primary Reading Inventory scores
(Texas A&M University, 2004-09-30) Davis, Jill Marie
The purpose of this study was to examine the impact of School Home Links activity guide homework on kindergarten Texas Primary Reading Inventory scores. Student Texas Primary Reading Inventory (TPRI) scores were obtained and analyzed for gains in score from the Middle of Year (MOY) and End of Year (EOY) administration. Parents were provided School Home Links Activity Guide Homework to use with their child on a weekly basis for twelve weeks. This group formed an experimental group. A control group did not receive SHL activity guide homework. For the control and experimental group each student's letter/sound score was entered into SPSS for the MOY and EOY TPRI, and average gains were calculated. Groups of students were isolated and analyzed for gain based upon participation in a district reading program, and/or high or low parental involvement in SHL activity guide homework. Research in the upper grades shows that homework completion and parent involvement positively affect student achievement. Students whose parents are involved in their education reap many benefits. These benefits include higher academic achievement (Davies, 1991). Fuller & Olsen (1998), Davies (1991), and Epstein (1995) believe parent involvement is a stronger indicator of student achievement than socioeconomic status, parent education, ethnicity, or any other indicator. The research supports the use of homework for upper grades. The results of this study remain inconclusive for kindergarten age students. This study shows that there is no statistically significant difference between experimental and control group kindergarten TPRI scores when homework is an independent variable.
A new approach for fast potential evaluation in N-body problems
(Texas A&M University, 2004-09-30) Juttu, Sreekanth
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.
Predicting injury among nursing personnel using personal risk factors
(Texas A&M University, 2004-09-30) Gjolberg, Ivar Henry
The purpose of this thesis was to develop a means of predicting future injury among nursing personnel working in a hospital system. Nursing has one of the highest incidence rates of musculoskeletal injuries among U.S. occupations. Endemic to the job are tasks such as rolling, sitting, standing, and transferring large, and often times, uncooperative patients. These tasks often place large biomechanical stresses on the musculoskeletal system and, in some cases, contribute to or cause a musculoskeletal injury. Given the current nursing shortage, it is imperative to keep nurses injury-free and productive so they can provide patient care services. Even though a large number of nursing personnel are injured every year and most are exposed to these high levels of biomechanical stress, the majority of nurses are injury-free. The question then arises "Why do some nurses have injuries while others do not?" The purpose of this thesis was to determine whether individual attributes in a population of nurses were associated with risk of future injury. The subject population was comprised of 140 nursing personnel at a local hospital system hired between April 1995 and February 1999. Data on individual attributes, such as patient demographics, previous injuries, posture, joint range of motion, flexibility, and muscular strength, was ascertained during a post-offer screening on these personnel. Twenty six (19%) nurses experienced an injury associated with the axial skeleton. Chi square test for homogeneity for the categorical predictor variables, and the Student's T-test for continuous predictor variables were used to determine if any individual attributes were associated with future injuries. None of the variables were associated with a risk of future axial skeletal injury. Practical application of these results for St. Joseph Regional Health Center, and possibly other acute care facilities, directs us to stop costly pre-employment/post-offer testing for the purpose of identifying injury prone nurse applicants. Secondly, it allows the focus of limited resources to be on making the job safer through administrative and engineering controls.
Context-based metrics for evaluating changes to web pages
(Texas A&M University, 2004-09-30) Dash, Suvendu Kumar
The web provides a lot of fluid information but this information changes, moves, and even disappears over time. Bookmark lists, portals, and paths are collections where the building blocks are web pages, which are susceptible to these changes. A lot of research, both in industry and in academia, focuses on organizing this vast amount of data. In this thesis, I present context-based algorithms for measuring changes to a document. The methods proposed use other documents in a collection as the context for evaluating changes in the web pages. These metrics will be used in maintaining paths as the individual pages in paths change. This approach will enhance the evaluations of change made by the currently existing Path Manager, in the Walden's Paths project that is being developed in the Center for the Study of Digital Libraries at Texas A&M University.
Experimental and analytical studies of hydrocarbon yields under dry-, steam-, and steam with propane-distillation
(Texas A&M University, 2004-09-30) Ramirez Garnica, Marco Antonio
Recent experimental and simulation studies -conducted at the Department of Petroleum Engineering at Texas A&M University - confirm oil production is accelerated when propane is used as an additive during steam injection. To better understand this phenomenon, distillation experiments were performed using seven-component synthetic oil consisting of equal weights of the following alkanes: n-C5, n-C6, n-C7, n-C8, n-C9, nC10, and n-C15. For comparison purposes, three distillation processes were investigated: dry-, steam-, and steam-propane-distillation, the latter at a propane:steam mass ratio of 0.05. The injection rate of nitrogen during dry-and steam-distillation was the same as that of propane during steam-propane distillation, 0.025 g/min, with steam injection rate kept at 0.5 g/min. The distillation temperatures ranged from 115?C to 300?C and were increased in steps of 10?C. The cell was kept at each temperature plateau (cut) for 30 minutes. Distillation pressures ranged from 0 psig for dry distillation to 998 psig for steam-and steam-propane distillation. The temperature-pressure combination used represented 15?C superheated steam conditions. Distillate samples were collected at each cut, and the volume and weight of water and hydrocarbon measured. In addition, the composition of the hydrocarbon distillate was measured using a gas chromatograph. Main results of the study may be summarized as follows. First, the hydrocarbon yield at 125?C is highest with steam-propane distillation (74 wt%) compared to steam distillation (58 wt%), and lowest with dry distillation (36 wt%). This explains in part the oil production acceleration observed in steam-propane displacement experiments. Second, the final hydrocarbon yield at 300?C however is the same for the three distillation processes. This observation is in line with the fact that oil recoveries were very similar in steam- and steam-propane displacement experiments. Third, based on the yields of individual hydrocarbon components, steam-propane distillation lowers the apparent boiling points of the hydrocarbons significantly. This phenomenon may be the most fundamental effect of propane on hydrocarbon distillation, which results in a higher yield during steam-propane distillation and oil production acceleration during steam-propane displacement. Fourth, experimental K-values are higher in distillations with steam-propane for the components n-hexane, n-heptane, n-octane, and n-nonane. Fifth, vapor fugacity coefficients for each component are higher in distillations with steam-propane than with steam. Finally, Gibbs excess energy is overall lower in distillations with steam-propane than with steam. The experimental results clearly indicate the importance of distillation on oil recovery during steam-or steam-propane injection. The experimental procedure and method of analysis developed in this study (for synthetic oil) will be beneficial to future researchers in understanding the effect of propane as steam additive on actual crude oils.
Estimating uncertainties in integrated reservoir studies
(Texas A&M University, 2004-09-30) Zhang, Guohong
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.

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