The purpose of this study was to determine the extent to which Tinto's model of the dropout process applied to a national sample of community college students. Strict definitions of persistence were used in applying a Tinto-based model to both 2- and 4-year student samples from the High School and Beyond (HSB) data set. The primary focus of the study was to determine the relative effects of social and academic integration, in relation to student background characteristics, on two measures of persistence: persistence in the institution, and persistence in higher education. The data were analyzed using path analyses procedures. Results only partially supported Tinto's theory. Major findings revealed that: 1) background variables directly affected persistence, no matter how defined, 2) the ability of Tinto's model to explain persistence may be highly dependent on the criteria used in defining persistence, 3) the model may better explain institutional persistence than persistence in the system of higher education, 4) student background characteristics may be more influential than institutional characteristics in explaining the long term persistence behavior of students, 5) results indicated that the Tinto model's ability to explain persistence was dependent upon the criteria used for defining persistence/dropout. / Ed. D.

The nighttime losses from an integral collector storage (ICS) system were investigated. The significance of the sky temperature, wind speed, and ambient temperature on the losses were examined. Outdoor data was taken on several nights to characterize the thermal performance of an ICS system under various environmental conditions. Indoor tests were then performed under an artificial "nighttime sky" environment, with a simulated wind, in an attempt to duplicate the heat losses which occurred outdoors. The standard rating procedure which specifies the conditions for the heat loss tests for ICS systems was analyzed to see how well it characterizes the collector performance at night. Experimental results indicate a synergistic effect between the sky temperature and wind speed. The effects of wind on the losses from the ICS system overshadow the effects of small changes in sky temperature, but larger changes of sky temperature, with a constant wind speed, have a pronounced effect. It is recommended that both of these parameters be taken into account in heat loss tests in standard rating procedures. Indoor tests can duplicate outdoor heat loss results within 8 per cent. The minimum requirement for SRCC rating tests should be to monitor, record, and report the sky temperature. / Ed. D.