A survey of a systematically selected sample of former community college students who had.withdrawn prior to obtaining a degree showed that 86 percent were satisfied with the programs and services of the community college, 46 percent had completed their objectives before withdrawing, 44 percent had both completed their objectives and were satisfied with the community college, and that 81 percent intended to continue their education at either the community college or some other college. The study was conducted because of an increasing volume of criticisms of the community college due to the low proportion of students that complete requirements for degrees in that institution. This criticism appears unwarranted inasmuch as Frank Newman and others have reported that the majority of persons enrolling in community colleges do not abide by the conventional academic format that results in a degree. K. Patricia Cross and others have observed that "drop-out, drop-in, drop-out" students realize their educational objectives without ever receiving a "degree" from the community college. This study supports their observations. Since the institution that participated in the study is probably typical of many community colleges, this study indicates that community colleges are doing a reasonably good job of meeting students' expectations. / Ed. D.

Linear least-squares prediction methods are applied to cluster (two-stage) sampling problems in a finite population where auxiliary information is available. Two regression models which describe the behavior of the second-stage units and which utilize the auxiliary information are considered. For one model the optimum estimator of the total of the second-stage units and its mean square error (m.s.e.) are derived. The selection of clusters which minimize the m.s.e. are determined for certain cases. For both models a conventional estimator of the total is analyzed in the prediction theory framework. Optimum sampling designs for the conventional estimator are obtained for certain parameter configurations. A computer implemented study to compare the performances of the estimators for a wide range of parameter values is done. A practical problem is analyzed. / Ph. D.

Based on pretreatment levels of anxiety, 21 involuntarily confined forensic psychiatric patients were assigned to one of three experimental conditions: stress management training, stress discussion, or no treatment control. Measures of anxiety, physical health, mood, adherence to "irrational beliefs" hypothesized by Ellis (1962) to be related to dysphoric emotions, and a measure of hospital ward adjustment were collected before and after treatment. Subjects originally assigned to the waiting list control group later received exposure to either the stress management training condition or the stress discussion condition. Measures of nonspecific treatment effects generally showed that both group treatments generated equivalent treatment credibilities. The self-report measures of mood and physical health demonstrated that exposure to the stress management training condition resulted in pre to posttreatment improvement, while exposure to the stress discussion condition did not. Also, subjects exposed to the stress management training condition decreased their endorsement of "irrational beliefs," while subjects exposed to stress discussion condition did not. Neither condition resulted in reduced pre to posttreatment changes in state or trait anxiety or improved ward adjustment. It was concluded overall that the stress management training procedure was a moderately effective stress reduction technique for forensic psychiatric patients. Directions for future research are presented as interpretive limitations of the present results. / Ph. D.

The rate of the aqueous transformation of aragonite to calcite was measured at 50°, 77°, and 101°C. The observed mole fraction calcite versus time relationship can be fit by the integrated rate model: t = [(3/C₂)(1-X)2/3 + (3/C₁)(X2/3)/[K₂-K₁] The constants C₁ and C₂ combine geometric factors, especially relative surface areas of the solids, K₁ and K₂ are the thermodynamic equilibrium constants for aragonite and calcite respectively. Apparent activation energies (E_A’) and absolute rates were calculated from Arrhenius plots of data from this study and others: E_A’ Conditions Material Time-50% CAL, 25°C Metzger and Barnard, 1968 58 kJ mol⁻¹ wet cm cubes 2.25X10² yr Taft, 1967 67 wet syn. powder 2.0X10⁻¹ This study 55 wet syn. powder 5.7X10⁻² Brown et al.,1962 373 dry 4.7X10³³ The E_A’ for this study is comparable with that of Metzger and Barnard indicating a similar mechanism, but absolute rates differ dramatically because of the different geometries of the run material. The dry transformation rates are so slow at diagenetic temperatures that this mechanism is of no importance geologically. Because the rate of the transformation is dependent on the geometry of the reacting system it is not surprising that most studies of neomorphic calcites find that the calcite textures are related to the original aragonite textures. Three transformation regimes, macroscale (passive dissolution), mesoscale (chalk zone), and microscale (thin film) dissolution-precipitation, are proposed to explain the variability in observed diagenetic calcite textures. These are differentiated by the surface area/solution ratio in the reaction zone. In general the smaller the geometric factor in the rate equation. i.e. the smaller the surface area/solution ratio, the slower the transformation rate and the higher the degree of precursor fabric retention in the neomorphic calcite. / Master of Science

M. A.

With increased use of pallets constructed utilizing structural panel decks, there is a need for a standardized, reliability-based design system, PDS-PANEL, to assist in the design and manufacture of panel-deck pallets. The primary objective of this research was to develop finite element models which predict the static bending behavior of pallets with at least one panel deck. stringer and block pallets were modeled using plate elements to simulate deck behavior and were validated by comparing predicted deflections to experimentally measured deflections. Differences were considerably less than the allowable 15 percent for both stringer and block models. Sensitivity studies conducted with these models provided a rational basis to simplify models for use in the existing PDS-PANEL program developed at Virginia Polytechnic Institute & State University. Simplified models were required to have solution times of less than 2 minutes on a 286 type or more powerful personal computer (PC). / Ph. D.

This research was undertaken to determine the effect that computer aided design (CAD) had on the spatial visualization abilities of selected gifted adolescents. The following hypotheses was tested: Subjects receiving instruction in CAD will show improvement in spatial visualization ability, as measured by the Revised Minnesota Paper Form Board (RMPFB) test. when compared to the subjects not receiving CAD instruction. The experimental group consisted of 20 students enrolled in the CAD course offered in the 1991 Virginia Governor's School of Technology. The control group consisted of 20 Governor's School students not enrolled in the CAD course. Both groups were pretested using the RMPFB test Form AA to measure entry level spatial visualization. A treatment consisting of three weeks of CAD instruction using CADKEY 3.5 was given to the experimental group. Following the treatment both groups were post tested using the RMPFB test Form BB to determine their existing level of spatial visualization ability. The nonequivalent control group design was used in this study since the experimental group was an intact group and therefore not randomly assigned. ANCOVA statistical analysis was used to determine if there was statistical significance of the post test scores. / Ph. D.

An experimental design, (the pretest/posttest design) was used in this study to investigate the efficacy of substance abuse treatment using two instruments, the Addiction Severity Index (ASI) and the biopsychosocial assessment. Fifty-six subjects admitted to the SYMBAS TEAM Substance Abuse Treatment Program were assessed during the initial stage of treatment using the biopsychosocial assessment and the ASI. Through the process of random selection, subjects were placed in one of two groups, an experimental group or a control group. Counselors working with the subjects in the experimental group had access to the results of the ASI and biopsychosocial assessment for treatment planning, and the counselors working with the subjects in the control group had access only to the results of the biopsychosocial assessment. At the end of treatment (gO-days), the subjects in both groups were re-assessed using the ASI to determine what differences, if any, occurred between the two sample groups. Data was analyzed using descriptive statistics along with the Student test. Results revealed that there were no statistically significant differences between the two sample groups at the .05 alpha level. However, significant reductions between the ASI pre- and posttests mean scores were noted among several of the variables in both sample groups. Also, the counselors' perceptions of the ASI suggested that the ASI was preferred over the bippsychosocial assessment for treatment planning, because of its structure and the amount of time required to administer the instrument. / Ed. D.

This thesis discusses the research and development of a program to aid the aircraft designer with determining the pilot's visual acuity. The discussion involves the use of Object-Oriented programming, the use of a graphical user interface based upon the graphics standard PHIGS (Programmers Hierarchical interactive Graphics System) and the integration of this Pilot's View Module with an existing aircraft CAD (Computer Aided Design) program known as ACSYNT. The result is a program that lends itself to reuse and easy modification and is device independent. The main purpose of the pilot's view module is to provide total vision plots for the pilot in accordance with the military standards as stated in the document 850B. These standards include visibility design goals for several types of aircraft as well as methods for calculating and presenting the vision plots. The integration of the pilots view module with ACSYNT affords the designer the ability to examine the trade-offs associated with a particular cockpit design and the performance of that design within one CAD program. / Master of Science

A novel micromechanical model for predicting the failure of polymeric and ceramic matrices under an applied global tensile loading is presented. The model is based on a Weibull statistical type of approach and incorporates eleven different variables to simulate different micromechanical failure phenomenon. Through the variables, the model incorporates such phenomenon as fiber-fiber interaction; matrix-fiber interaction; damage due to processing; and local stress distribution at the interphase. The effects of the load sharing constants and shape parameter on failure are studied. A software package, used in the Windows environment, was also developed to perform a numerical analysis of the model. / Master of Science