This research investigates the modeling and simulation, using the state transition approach to nonlinear system simulation, of a DC drive system. The drive system that was modeled is a closed loop system composed of a velocity loop with an inner current loop. The power stage is composed of a pulse generator module and a scr bridge, while the motor is a permanent magnet DC motor. A detailed development of each module model is included to reveal the open loop characteristics of the system. A total system state model was developed from each of the modules and closed loop simulations were run. The results show that the system may be modeled and simulated using this technique. However, the exactness of the simulation is heavily dependent on the DC motor parameters selected for the model. / Master of Science

Thirty-nine overweight college women were assigned to one of three weight reduction groups: diet control (DC), DC + low intensity exercise (LX), DC + moderate intensity exercise (MX). All women were tested for VO₂peak and percent fat. The DC included a previously designed nutrition education and behavior modification program held one time per week which prescribed a caloric intake based on body weight to result in a 1000 kcal•day⁻¹ dietary deficit. Exercise groups were asked to also attend three exercise sessions each week. In addition to a warm up and cool down, LX exercised at a heart rate corresponding to 40% of VO₂peak for 35 minutes per session while MX exercised at 70% of VO₂peak for 20 minutes. Exercise durations were chosen to match LX and MX for total exercise caloric expenditure. Heart rates were self-monitored every 10 min and sporadically verified by the exercise leader. At the end of the 8 week program, there was an overall drop out for the three groups of 34%, with the DC group having the highest attrition (50%) relative to LX ( 40%) and MX (20%) groups. VO₂peak did not change significantly after the 8 week program in any group, perhaps as a function of the modest exercise stimulus and/or a sharp reduction in attendance noted in the final 2 weeks. However, an improvement in cardiorespiratory efficiency was indicated by the significant reduction of heart rate at submaximal workload III (MX = -12, LX = -10, DC = -6 bts·min⁻¹ ). A significant mean decrease of 2.93 ml·kg⁻¹·min⁻¹ in VO₂ at the same submaximal workload was noted. All groups lost a significant amount of body weight over the eight weeks. The trend in average body weight loss (DC=4.0, MX=3.6, LX=3.3 kg) was opposite to that of % fat loss (LX = 5.1, MX = 3.9, DC= 2.2%). These differences were not significant but show a tendency for exercise coupled with diet control to enhance fat but not total body weight loss. Thus, the treatment which enhanced fat loss and most strongly enhanced attendance was a moderate intensity exercise added to diet control. / Master of Science

A qualitative and quantitative comparison of the vomeronasal organ was made of the autarchoglossan lizards: Scincella lateralis, Eumeces fasciatus, Eumeces inexpectatus, and Ophisaurus ventralis, and the ascalobotans: Sceloporus undulatus, Hemidactylus turcicus, and Xantusia vigilis. As judged by the thickness of the vomeronasal sensory epithilium the vomeronasal organ was most highly developed in Ophisaurus venteralis and least developed in Sceloporus undulatus. A comparison of the relationship between the vomeronasal sensory epithelium thickness and vomeronasal capsule length of autarchoglossans and ascalobotans supports the hypothesis that the vomeronasal organs of of autarchoglossans are larger than ascalobotans. However, a comparison of mean residuals for the species utilized in this study indicate that the relative size of the vomeronasal organ may be related to ecology as well as systematic relationships. Lizards that are secretive, fossorial, nocturnal or crepuscular have a tendency to have relatively well developed vomeronasal organs as measured by the thickness of the vomeronasal sensory epithelium, and lizards that are diurnal, visually oriented, and aboreal generally have smaller, less developed vomeronasal organs. Scincella lateralis responds to both visual and chemical cues of prey. A visual stimulus is associated with an increased rate of tongue flicking, orientation to the prey, and attack behavior. Chemical cues are unimportant when the visual cue (movement) is present. When prey are non-moving or dead, chemical cues enable the lizard to distinguish potential prey from inanimate objects. Vision and the chemical senses interact in a complex way to form the predatory repertoire of Scincella lateralis. Lizards may adopt one of two basic foraging strategies; an active foraging strategy or a sit-and-wait strategy. Lizards in the active foraging mode use both visual and chemical cues to detect moving or non-moving prey. A lizard in the sit-and-wait mode uses vison to detect prey movement. However, if the prey eludes capture after a lizard in the sit-and-wait mode begins its predatory attack, chemical cues may be used to track or identify the prey. / Master of Science

An experimental investigation was made to determine the role of gravitational and surface tension forces in the migration of liquid water through fiberglass insulation materials. Straightforward experimental procedures were devised to effectively isolate and quantify flow parameters considered important in describing the flow mechanisms involved. The study was conducted to supplement an earlier investigation into the thermal performance of wetted insulation materials. Darcy's Law was found to apply for the regime of flow encountered in which liquid water flows under the force of its own weight in horizontal rooftop insulation. Experimental determination of the constant of proportionality in Darcy's Law, the hydraulic conductivity, is all that is needed to describe the migration of liquid water in saturated fiberglass insulation. Capillary forces, originally thought to play a significant role in the movement of liquid water through fiberglass insulation, were found to be negligible. Capillary rise up a column of insulation measured no higher than 13 mm. / M.S.

The effects of fiber reactive and direct dyes on certain physical properties (tenacity, elongation, and initial modulus) of cotton fibers were investigated. Raw cotton fiber and raw yarn spun from the same batch of fiber were obtained. Fiber and yarn were processed by scouring, bleaching, and dyeing with both dyes, using an Ahiba Texomat Dyeing Apparatus, and the appropriate chemical systems. Fibers from treated fiber and fibers removed from treated yarns were tested after each treatment step, using an Instron Tensile Tester. The Wilks multivariate F test was used to determine whether or not significant differences existed between sequential treatments, and between fibers treated as fiber or as yarn. When significant differences were indicated, univariate analysis of variance was computed to identify the property(s) responsible. The results of this study indicated that the physical properties of both fiber reactive dyed and direct dyed fibers were not significantly different from each other or from the bleached fiber from which they were dyed. The properties of bleached (and dyed) fibers were significantly different (lower tenacity and elongation, higher initial modulus) from untreated or scoured fibers, indicating that the bleaching step was responsible for most of the changes noted. The properties of fibers treated as fiber were generally different (lower tenacity, higher elongation, lower initial modulus) than those of fibers removed from yarn. / M.S.

A procedure to rapidly screen Clostridium botulinum type A and Clostridium sporogenes for plasmids was developed. Plasmid profiles of five C. botulinum type A strains and seven C. sporogenes strains were determined and a possible relationship of plasmids to toxin production was examined. The differentiation of these organisms by plasmid fingerprinting was also studied. The plasmid isolation procedure was a modified cleared lysate technique, including lysis under alkaline conditions. Samples were subject to agarose gel electrophoresis to detect plasmid DNA. Culture age affected plasmid detection due to changes in the cell density and lysing efficiency. Middle to late log cultures were used throughout the study because they provided optimum plasmid detection. Four out of five C. botulinum type A strains and three out of seven C. sporogenes strains contained extrachromosomal DNA. For those C. botulinum type A strains which contained plasmids, there were always two, one 15 to 15.6 Mdal and the other 6.2 Mdal. C. sporogenes showed less consistency in plasmid size and number and their plasmids were generally of a greater molecular weight than those in C. botulinum type A. One C. sporogenes strain contained two plasmids and two strains contained one plasmid. Toxin production may be plasmid-mediated in the plasmid containing strains, but there was no apparent general relationship, because one of the toxic strains did not show the presence of plasmids. Plasmid screening may be useful in the differentiation of these closely related organisms without toxin testing. / Master of Science

This study investigated several facets of the environmental coping process. Environmental coping was defined as any behavioral or cognitive attempt to reduce annoyance resulting from bothersome environmental conditions. In this study, library patrons using study carrels were observed while two people talked nearby. The library patron's behaviors in response to this event were recorded. In addition, self-report data were collected by means of follow-up questionnaires. Drawing on the literature from areas of research such as environmental stress, the coping process, and the effects of perceived control, four hypotheses were proposed. In summary, these hypotheses proposed that people would attempt to deal with the intrusion created by others talking nearby through indirect means first, and that people would attempt to"make do" (satisfice) rather than exert control over environmental events (optimize). Due to methodological difficulties, no definite conclusions could be drawn. Suggestions for methodological refinement in this area of research were offered and conceptual issues discussed. / M.S.

M. S.

M. S.

Ph. D.