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Typescript (photocopy). / Digitized by Kansas Correctional Industries

QC 351 A7 no. 20 / The control system described in this thesis was designed to automatically guide the position of photographic plates during long exposures of astronomical objects. The system senses the position of the guide star which is being used as a position reference, and moves the photographic plate in two orthogonal directions in order to maintain a constant position of the image of the astronomical object on the photographic plate. The system was designed to have a bandwidth of 35 radians per second in order to track the worst case image excursions due to atmospheric turbulence and telescope motion. The closed loop transient response of the system was determined from considerations of final image resolution of the photographic plate. Due to the necessity of guiding on stars of unknown brightness the system incorporated an automatic gain control loop within the forward control loop and was made unconditionally stable by high order feedback. In operation on the Steward Observatory telescopes, the system has made a significant increase in photographic plate resolution over manually guided plates.

Fifteen three-, four-, and five-year olds were assessed for the amount of time they spent on, off, under, and touching play equipment in an environment with play events and one without (i.e. the platform condition), An ABAB experimental design was used. Treatments lasted 3 days a week for 4 consecutive weeks, with each age group being videotaped 20 minutes each day, Data collected from the videotapes was applied to a 3 x 4 (age x treatments) ANOVA and revealed at the . 05 level (a) significantly more on and touching in the play event conditions; (b) significantly greater off and under in the platform (non play event) conditions; (c) a significant increase in off behavior from the first to second play event condition; (d) three-year-olds spent more time under and touching, and significantly less time on; and (e) significant interactions for on and under which seemed to be caused by the three-year-olds showing an inordinate amount of under behavior in the second platform condition, These results supported the assumption that play events would cause a significant increase inactive child-equipment interaction.

Certain applications have recently appeared in industry where a traditional bar code printed on a label will not survive because the item to be tracked has to be exposed to harsh environments. Laser direct-part marking is a manufacturing process used to create permanent marks on a substrate that could help to alleviate this problem. In this research, a 532 nm laser was utilized to create a direct-part marked Data Matrix symbol onto carbon steel substrates with different carbon content. The quality of the laser marked Data Matrix symbol was then evaluated according to the criteria outlined in the ISO/IEC 16022 bar code technology specification for Data Matrix. Several experiments were conducted to explore the effects that different parameters have on the quality of the laser direct-part marked symbols. First, an experiment was conducted to investigate the effect of two different laser tool path patterns. In later experiments, parameters such as type of carbon steel, percent of laser tool path overlap, profile speed, average power and frequency were found to have significant effects on the quality of laser direct-part marked Data Matrix symbols. The analysis of the results indicated that contrast and print growth were the critical standard performance measures that limited laser direct-part marked Data Matrix symbols from achieving a higher final grade. No significant effects were found with respect to other standard performance measures (i.e., encode, axial uniformity, and unused error correction). Next, the experimental data collected for contrast and print growth was utilized as training, validation and testing data sets in the modeling of artificial neural networks for the laser direct-part marking process. Two performance measures (i.e., mean squared error and correlation coefficient) were employed to assess the performance of the artificial neural network models. Single-output artificial neural network models corresponding to a specific performance measure were found to have good learning and predicting capabilities. The single-output artificial neural network models were compared to equivalent multiple linear regression models for validation purposes. The prediction capability of the single-output artificial neural network models with respect to laser direct-part marking of Data Matrix symbols on carbon steel substrates was superior to that of the multiple linear regression models. / Graduation date: 2004

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.