A study of unstable axisymmetric separation was conducted using spiked cones in flows with free stream Mach numbers, M, of 6.0 and 2.21. Reynolds numbers based on the model diameter, Re_D, were 0.13x10⁶ and 0.9x10⁶ at M = 6.0 and 0.05x10⁶ and 0.12x10⁶ at M = 2.21. The body cone half angle, Φ_D, for the range 30° ≤ Φ_D ≤ 90°, and non-dimensional spike length, l/D, up to l/D = 3 were varied in small increments. Pressure measurements made on the model face using fast response instrumentation showed the pressure to exhibit a regular or periodic wave form. These wave forms were analyzed in terms of the time averaged frequency, f, and amplitude, Δp. Based on these pressure measurements synchronized with spark photographs of the flow, two distinct modes of unstable axisymmetric flow were observed namely, oscillation and pulsation. Both modes showed the non-dimensional frequency to decrease as t/D was i~creased independent of Φ_D, Re_D, and M. The amplitude, Δp was found to be a strong function of l/D, Φ_D , Re_D and M. However, the maximum Δp of the oscillation mode was one tenth that of the pulsation mode which was of the order of magnitude of the pitot pressure. To provide further information on which a theoretical analysis could be based specialized experiments were carried out on specific models. These techniques included thin film gauges and a high speed cine in the streak mode. These data were then examined with the purpose of establishing the mechanisms of the modes of unstable flow. An original hypothesis was developed for the oscillation mode based on a viscous mechanism. Comparison with experiment was made which showed this hypothesis to be a sound physical model. The pulsation mode was similarly treated revealing this mechanism to be of an inviscid nature. Finally, the results of this study were used to predict the unstable flow parameters of an idealized ablation model of current practical interest. A comparison of this with experiment shows the results of the present study to provide a useful engineering guideline. / Ph. D.

An approximate spin-extended method is developed in which the Occupation Numbers of the Natural Orbitals of Charge are varied but the orbitals themselves are frozen. A number of techniques for obtaining appropriate Natural Orbitals of Charge are presented and these techniques are employed in semi-empirical and Ab-Initio studies. The molecules chosen for the Ab-Initio study, O₃, F₂ and C₂, are particularly interesting as Restricted Hartree-Fock (RHF) theory fails to provide an adequate description of these systems at their equilibrium geometries. The results of this work indicate that Approximate SpinExtended Hartree-Fock (ASEHF) theory provides a qualitatively acceptable description of bond dissociation, correctly predicts the symmetry of molecular states where RHF theory fails, and provides an efficient means for obtaining a significant amount of correlation energy in molecular calculations. Moreover, when the Generalized Valence Bond form of the ASEHF wavefunction is employed, a particularly useful description of the molecule is obtained. Specifically, the success or failure of the Woodward-Hoffman becomes transparent when the system is analyzed in terms of this wavefunction. / Ph. D.

Quercus rubra seedlings were subjected to five treatment factors in a factorial design replicated ten times in a randomized complete block design. The factors included: (1) Pisolithus tinctorius inoculated seedlings or non-inoculated seedlings; (2) nitrogen fertilizer supplied as sodium nitrate or as ammonium chloride; (3) fertilization at 15 days or at 40 days after planting of seed; (4) rates of nitrogen applied at 0.0, 0.0133, 0.0266, or 0.0532 g N per seedling; and (5) the seedlings grown for 60, 100, or 140 days. All 960 seedlings were grown in a peatmoss/vermiculite medium in one-liter containers in a greenhouse and fertilized at the time of planting with a nutrient solution excluding nitrogen. Growing medium moisture was maintained between 0.3 and 1.0 bars matric suction throughout the growing periods. Details are given with regards to inoculum synthesis, seed planting, care for seedlings, fertilization and media nutrient status, and data collection procedures. Ectomycorrhiza formation was observed as early as 18 days after planting. All inoculated seedlings (480) were ectomycorrhizal with P. tinctorius. Ectomycorrhizae other than those characteristically produced by P. tinctorius were not observed and all non-inoculated seedlings (480) were free of ectomycorrhizae. Ectomycorrhiza formation was enhanced with late nitrogen applications; however, infection was low on unfertilized seedlings. Mycorrhizal seedlings generally had less basal area, total seedling weight, root weight, leaf phosphorus weight, and leaf phosphorus percent than non-mycorrhizal seedlings. Mycorrhizal seedlings also had decreased leaf areas and green leaf area percents than non-mycorrhizal seedlings. Total seedling weight was enhanced with early applications of nitrogen fertilizer. Non-mycorrhizal seedlings fertilized with ammonium chloride generally had greater basal area, total seedling weight, and root weight than non-mycorrhizal seedlings fertilized with sodium nitrate. The probable effects of P. tinctorius in enhancing leaf damage and reducing seedling growth and leaf phosphorus contents are discussed. Several specific fertilization treatments are recommended for the production of large and healthy mycorrhizal and non-mycorrhizal northern red oak seedlings. / Ph. D.

Introduction Manufacturers have recently been using comparative advertising for the apparent purpose of producing clearer and more favorable brand images. A number of empirical studies have measured the effects of manufacturer sponsored comparative advertising and identified some situations where it is more effective than noncomparative advertising. However, no study has addressed the feasibility of retail sponsored comparative advertising. Statement of the Problem The importance of store image to the retailer is well documented. Advertising plays an important role in the development and enhancement of store images. Despite this, very few guidelines exist to aid retailers in their search for advertising approaches which will produce favorable store images. Therefore, this study dealt with store image. It explored the degree to which store image was enhanced when a retailer employed comparative advertising. Methodology An after-only with control group experimental design was utilized to generate data measuring the relative effects of North Carolina department store sponsored comparative and noncomparative advertising. A preliminary study facilitated development of four mock comparative and noncomparative newspaper advertisements. Together, the ads stressed sponsoring store superior performance across seven store image attributes (easy to find items you want, friendly personnel, reasonable prices, good buys, good service, fast checkout, and low pressure salespeople). Comparative ads claimed sponsoring store superior performance on these seven attributes over three competing stores. Three dependent variables were used to measure comparative and noncomparative advertising effects. These variables were: (1) overall store image as measured by a multiattribute attitude model, (2) performance evaluations of the seven advertised attributes and (3) belief levels for claims made in experimental ads. The study hypothesized noncomparative, comparative and control group differences in these dependent variables. Analysis of variance was used in conjunction with the Scheffe multiple comparison test procedure to identify significant group differences. Results and Conclusions The results of hypotheses testing produced the following major findings: Hypothesis 1 No significant group differences in overall store images. Hypothesis 2 No significant group differences on: low pressure salespeople, good buys on products, good service, reasonable prices for value, and fast checkouts attributes. Comparative advertising significantly less effective than current advertising (control group scores) for "easy to find items you want" attribute. Noncomparative advertising significantly less effective than current advertising for "friendly personnel" attribute. Hypothesis 3 Noncomparative advertising significantly more effective than comparative advertising for 9 out of 28 ad claims and significantly more effective than current advertising on four claims. Comparative advertising significantly less effective than current advertising for three claims. Hypothesis 4 In general, noncomparative advertising was significantly more effective than comparative advertising promoting attributes and making claims aimed at specific segments as defined by age, sex, income and store loyalty. In a smaller number of situations, the noncomparative approach was significantly more effective than current advertising. The results of hypotheses testing clearly showed comparative advertising producing effects significantly less favorable than noncomparative or current advertising. Whether or not significant group differences existed, noncomparative advertising consistently produced effects more favorable than comparative or current advertising. Although it has limitations, this study strongly concludes that retailers should avoid the use of comparative advertising. / Ph. D.

The workplace environment is composed of the sum total of all physical and behavioral conditions that can affect the safety and health of the workers. This dissertation presents an economic analysis which explains the processes which determine the actual safety and health properties of the workplace. Further than this, economic theory is used to predict how allocation of resources can affect the degrees of safety and health that will be present. From this analysis there follows a set of testable hypotheses on the effects of various government programs on the level of environmental quality contained in the workplace. This study is not concerned with a benefit-cost analysis of occupational safety and health laws. Rather, this study uses economic theory to develop the expected impacts of administrative rule enforcement upon injury control considerations within the firm and by the workers. The focus of the study is the administration of the Occupational Safety and Health Act of 1970 by the Occupational Safety and Health Administration (OSHA). The effectiveness of OSHA enforcement activity in achieving two legislative goals is examined. One goal is the dissemination of information on previously unperceived job hazards. The other is to increase the injury control efforts of firms. Since both OSHA and workmen's compensation programs are administered in this country, discussion is carried out within a world in which workmen's compensation laws are already present. / Ph. D.

Purpose This study was undertaken to identify the lesson topics that are being taught in exploratory agriculture classes in Virginia and compare these lesson topics to lesson topics that should be taught in exploratory agriculture classes as perceived by exploratory agriculture teachers, State Department of Education agricultural education supervisory staff, teacher educators in agriculture, and vocational directors in those school systems offering exploratory agriculture classes. Population The population of this study consisted of 50 teachers of exploratory agriculture, 11 teacher educators, 8 agricultural education supervisors, and 15 vocational directors. Eighty-nine percent, or 75, of the potential respondents marked and returned the opinionnaire in usable form. Procedure Two instruments were developed for purposes of this study; one for teachers of exploratory agriculture classes and one for agricultural education supervisors, agricultural teacher educators and vocational directors. A list of possible lesson topics that might be taught in exploratory agriculture was selected from a review of literature on exploratory agriculture and this list of lesson topics was included on both instruments. The instruments were evaluated by a panel of experts and pilot tested. Respondents were asked to check lesson topics that should be taught in exploratory agriculture classes, and to rate the importance of those lesson topics to an exploratory agriculture class on a 1 - 5 point Likert scale. Teachers were also asked to check lesson topics they are presently teaching and to record the amount of time, in class periods, they spend on each lesson topic. Summary of Findings None of the 49 lesson topics on the opinionnaire were taught by 100 percent of the teachers, and two lesson topics were not taught by any teacher. Additional lesson topics in technical agriculture were added by 52 percent of the teachers. The lesson topic taught by the largest number of teachers (N = 32) was "Understanding the meaning of agriculture and agribusiness," and the largest mean number of class periods (2.72 class periods) was also spent on this topic. Respondents indicated that 39 of the lesson topics on the opinionnaire should be taught in exploratory agriculture classes. The lesson topic ranked the highest on mean importance was "Exploring the occupational opportunities in agriculture" with a mean importance of 4.30. Thirty of the 39 lesson topics that should be taught in exploratory agriculture had frequency counts of 20 percent when compared to frequency counts for lesson topics presently taught by exploratory agriculture teachers. There were significant differences at the .05 level on 12 lesson topics when comparing the respondent groups on this perception of lesson topics that should be taught. On a comparison of the mean importance of lesson topics among the respondent groups, differences large enough to be of importance were found on four of the lesson topics. Major Recommendation The exploratory agriculture curriculum committee should give considerable attention to the findings of this study in the finalization of a state curriculum guide for exploratory agriculture classes. / Ed. D.

The purpose of this research was to study the management processes involved in the evolution of a selected community college developmental studies program. The particular program selected was characterized by many of the features identified by Roueche, Kirk, and Snow (Roueche and Kirk, 1973; Roueche and Snow, 1977) as important to program success. Features examined in this study were: high presidential priority of the program, staffing, organizational structure, credit for graduation based on developmental courses, non-punitive grading, transition from developmental to traditional college courses, integration of the counseling function with the developmental program, recruitment strategies for enrolling non-traditional students, and program evaluation. Specifically, this study sought to identify and explore those aspects of management which were instrumental in establishing the features. Such factors as leadership, work environment, organization, decision making, coordination, and innovation were considered in relationship to the establishment of the features. An exploratory case study was conducted at a Virginia community college which had implemented many of the features and which was generally recognized as having an outstanding developmental studies program. Data was obtained through personal interviews with faculty, staff, and key administrators as well as examination of institutional documents such as memorandums, Institutional SelfStudy, local research reports, and college bulletins. Additional data were also available through personal observations of the researcher. A major finding of this study was the way in which the President evidenced his high priority of the developmental program and the effect this priority tended to have in shaping the program. The active role of the President was repeatedly noted by administrators and faculty who perceived his continued support as crucial to program success. The general view of respondents was the presidential support, staffing specifically for developmental studies, and a separately organized division were of primary importance if other features were to develop. However, this study tends to support the conclusion that these latter features could be directly attributed to the priority placed by the President. The separately organized division and dedicated developmental staff were perceived as instrumental in the development and implementation of a number of features deemed essential to the program. These included: development of a comprehensive recruitment process for developmental faculty, program evaluation, and counselor integration into the program. Another significant finding of this study was that major decisions regarding the developmental program relied heavily on input and evaluation from faculty. / Ed. D.

The current energy crisis and subsequent rise in fuel costs has created extreme hardships on those persons living on restricted or fixed incomes. The objective of this design study was to create affordable housing for these people through the use of three areas: 1) energy conservative construction, 2) alternative energy systems, and 3) barrier free design. Through the use of the Skytherm solar roof pond system, woodburning stoves, and domestic solar hot water systems, the cost of using the units designed have been drastically lowered from that of an all-electric home. Additionally, through the use of barrier free design recommendations, housing has been created which is equally liveable for the non-handicapped and the handicapped person. / Master of Architecture

The attitudes toward nutrition and dentistry were studied in a group of senior dental students at Virginia Commonwealth University, Medical College of Virginia. The attitude statements were divided into three categories, nutrition and counseling, the nutrition counseling in their future dental practice, and nutrition education in dental school. Students responded positively or negatively to 30 statements related to nutrition and dentistry. Varying point values were assigned to each answer. High scores indicated a positive attitude toward nutrition. The results indicated that students have favorable attitudes toward nutrition. Their least favorable attitude was toward the inclusion of nutrition counseling in their future dental practice. However, they realized the importance of nutrition to good oral health and nutrition's role in the prevention and control of dental caries. The teaching of nutrition to dental students did not improve individual eating habits or reinforce already good habits. The students were confident that they would be able to recognize nutritional problems and make the necessary referrals. However, the students did not agree that the nutrition education they received prepared them to treat the nutritional problems they might encounter. Students who had favorable attitudes toward nutrition education also had favorable attitudes about including nutrition counseling in their dental practice. / Master of Science

This thesis is concerned with the use and development of mass matrices. A literature study is performed to determine the role of the mass matrix in the current state of the art of dynamic structural analysis. For simplicity and efficiency, the information obtained from the literature study is presented in a tabular format. A comparison study of three different types of mass matrices on the basis of frequency prediction is conducted. In order to perform the comparison study, a computer code was developed using beam-column elements to assemble the system mass matrix and calculate the eigenvalues and eigenvectors. This code was then added to the code developed in CE4002 - Matrix Structural Analysis and CE5980 - Computer Aided Structural Design. Test problems are presented and comparisons made with exact solutions and solutions from the literature. / Master of Science