The scarcity of usability studies on computer-aided design (CAD) systems has prompted three questions: (1) Is usability testing different for CAD systems than conventional software? (2) What role does domain expertise play in the use of CAD software since most CAD applications are not simple tasks? (3) How does the design parameters’ presentation affect the user's understanding of the design, the design domain, and the capabilities of the CAD system? This thesis addresses these three questions through the application of human-computer interaction (HCI) techniques in the development of a graphical user interface (GUI) for the metal-ceramic brazing process: First, a GUI for the metal-ceramic brazing process was designed and implemented. Subjects were then invited to test the GUI by performing a set of benchmark tasks. The results of these tests were analyzed, both to characterize design flaws in the interface, and to suggest redesign solutions to observed problems. The GUI was then refined based upon the test results and retested. To further aid in the understanding of the effects of the design parameters’ presentation, a usability evaluation was also performed for a finite element module of a state-of-the-art commercial CAD system (I-DEAS Master Series, version 1.3). This evaluation provided a comparison for the metal-ceramic interface with respect to interaction styles, presentation of domain knowledge, and task performance. This study demonstrated that HCI methodologies can be applied effectively to CAD user interface development. In particular, it encouraged the development of a usability-oriented process for developing usable interfaces. However, it also highlighted the difficulties posed by the complexity of a CAD system and the associated task analysis. It was observed that three distinct sets of knowledge are involved in the use of a CAD system: task knowledge, domain knowledge, and application knowledge. By separating and distinguishing the needs of these sets of knowledge, the CAD system developer is more likely to design a high-quality interface, one that supports the task performance while educating the novice user of the technical background of the application. It was also found that a clearly and intuitively organized interface can provide an invaluable insight for users into the functionality of the system and facilitate users' learning of the system. The subjects who participated in this study were inexperienced in both the application and the application domain and relied greatly upon the organization of the interface to lead them through the benchmark tasks. The organization of the system functions or, in the case of the metal-ceramic brazing interface, the design parameters, was shown to be crucial to the subjects' understanding of the application because it was the only source of guidance the subjects had as to how to perform the benchmark tasks. In particular, it was observed that the subjects had the tendency to align their thought process to that of the interface in their attempts to understand the system. / Master of Science

This study was initiated to determine the causes of lowered reproductive efficiency in mice selected for increased post-weaning gain. Four experimental groups were established: (1) Group C, the two control lines; (2) Group S, the four selected lines; (3) Group CS, the F₁ progeny from the 4 control line X selected line crosses; (4) Group SS, the F₁ progeny from 6 selected line X selected line crosses. Observations were as follows: (1) Estrous cycles were charted by vaginal smears and plugging rate, litter rate, and litter sizes recorded; (2) Ovulation rate was obtained by counting CL's at 3½ and 7 days after mating; (3) Fertilization rate was obtained at 3½ days after mating; (4) Pre- and early post-implantation losses were obtained at 7 days after mating; (5) Late post-implantation losses / were obtained 17 days after mating. Results were analyzed by analysis of variance. No significant differences between experimental groups were found for ovulation rate, fertilization rate, or embryonic mortality. Highly significant (P < .01) group differences were found for the number of days from introducing the male until a CP was observed. Group C plugged in an average of 3.39 days, whereas group S averaged 5.50 days. The number of days spent in proestrus, estrus, and metestrus were each significant (P < .01) for group differences, whereas diestrus was not significant. Plugging rate and litter rate, differed significantly (P < .01) as did litter size (P < .05) among the experimental groups. / Master of Science

The mixed oak-pine cover type was evaluated as white-tailed deer range on four study areas by measuring dry matter production of key forages and determining their nutrient composition. Composite diets containing plant species which represented the major portions of each seasonal diet as indicated by food habits studies, were mixed for the summer, fall and winter seasons. For the spring flush and spring seasons, individual key forages were analysed. All samples were assayed for soluble carbohydrates, lignin, phosphorus, gross energy, proximate composition, and in vitro dry matter digestibility. Digestible energy production in kcal/ha/day was calculated seasonally for key forages. The ratios of digestible energy available in key forages to that required by the estimated deer herd were 3.01, 5.94, 0.96, 2.14, and 1.23, for the spring flush, spring, summer, fall, and winter, respectively. These ratios indicate the potential of the study areas to support the estimated population density of 1 deer per 16.4 ha. The mixed oak-pine cover type appears to be adequate to support the estimated deer herd if 50 percent of the key forages are consumed seasonally but inadequate if only 25 percent are used. During all seasons, forage protein appeared to be adequate and phosphorus was possibly lower than that required for optimal animal performance. / Master of Science