The turbulent wakes behind a streamlined drag body, a jet-propelled body, and a propeller-driven body are studied experimentally in a subsonic wind tunnel at a principal nominal free-stream velocity of 206 ft/sec. The wakes produced by the latter two bodies are momentum-less. Mean flow data taken at five axial stations (X/D = 2, 5, 10, 20, and 40) downstream of the sterns of these bodies include velocity and static pressure distributions. The streamwise variation of the maximum values of axial turbulence intensity and radial shear stress are also presented. The mean flow data for the wake behind the drag body compare favorably with previous experiments and establish a rigid reference for the wakes behind slender, self-propelled configurations. The downstream rate of decay of |(U_E-U_c)_max U_E| is essentially the same for the drag and propeller-driven bodies, whereas the decay for the jet-propelled body is substantially faster. A self-similar character is exhibited in the wake of the drag body, but the wake of the propeller- driven body appears to be self-similar in the usual sense only in the inner region. As for the basic turbulence behavior, the magnitude of the axial turbulence intensity is greater for the jet-propelled model than the other models, and the absolute value of the radial shear stress is greater (beyond X/D = 2) for the propeller driven model. The rate of decay of (√u'²)_max is faster for the propeller-driven model than the jet-propelled model; however, the rate of decrease of radial shear stress is faster for the jet-propelled model. A comparison of the axial variation of |(U_E-U_c)_max U_E| with numerical predictions using a turbulent kinetic energy method shows very good agreement for the drag and jet-propelled bodies. The shear stress trends are predicted well in all cases. / Ph. D.

An experimental study of the turbulent wake produced by a stern-propellor-driven body moving in a temperature-stratified fluid is presented. The velocity and thermal boundary layers on the body upstream of the propellor are also examined. Mean flow velocities, static pressure, flow angularity and mean temperature distributions are reported at five downstream stations, Z/0 = 0.33, 1 .0, 2.0, 3.0, and 4.0. Turbulence data, including temperature fluctuations are reported at Z/D = 0.33 and Z/D = 4.0. The measurements were taken using thermocouples and pitot tubes of various size, a yawhead probe, a cross-wire hot-wire, and a straight-wire hot-wire as appropriate. For measuring the temperature fluctuations, the straight hot-wire probe was operated in the low-overheat mode to maximize temperature sensitivity. The testing was conducted in the Virginia Tech 6’ X 6’ subsonic wind tunnel at free-stream Re_D = 2.04 X 10⁵. The temperature variation provides a means of tracing the wake development in the near-body region. The principal effect of the propellor is to induce a more or less rigid rotation immediately downstream of the body. The fluid is apparently mixed much less than was anticipated. Temperature fluctuation is mild across the wake except in the vicinity of the propellor tips where it becomes relatively large. The high temperature fluctuation often occurred in regions of low mean temperature gradients which indicates that current modeling techniques should be re-examined. / Ph. D.

An initial study of the delayed coincidence technique and methods of analysis has been made. Three methods of analysis are attempted: the slope, the method of moments and the "unfolding" method. Necessary corrections to minimize errors of calculation are proposed and numerical checks of the methods are performed. Half lives of the levels 829 and 864 keV in ¹¹⁵In were separately measured by means of β-γ delayed coincidence technique. A Ge (Li) detector of 4cc active volume, in conjunction with a constant fraction timing discriminator, was used to detect the γ- branch. The data from this experiment were analysed by the above mentioned methods and the proposed corrections were made. Good correspondence was obtained between the unfolding and the method of moments, while the valµe obtained using the slope method was slightly higher. The numerical test of the analysis methods could not explain this difference completely. It was assumed that the difference was due to fluctuations in the collected data. / Master of Science

The impact of metropolitan dominance on the diffusion of family planning in the Philippines was analyzed. Hypotheses based on the diminishing effect urban centers have on knowledge approval and practice of family planning as distance from the metropolitan core increases, size of the local urban center decreases and level of individual cosmopolitanism increases were tested by means of bivariate correlations. In addition the predictive value of these variables was assessed by chi-square and gamma coefficients. The findings indicate, 1) a decreasing linear relationship between metropolitan dominance and the diffusion of family planning variables; 2) a curvilinear relationship between size of local urban center and the diffusion of family planning; 3) a decreasing linear relationship between level of individual cosmopolitanism and the diffusion of family planning. Furthermore, the findings indicate that the distance from the metropolitan core effect is vitiated when the size of the local urban center exceeds the 20,000. However, the distance from the metropolitan core effect is not conditioned by the level of individual cosmopolitanism. / Master of Science

The need to extend light water reactor spent-fuel on-site storage requirements and the future need to relieve resulting stockpiles necessitates the determination of optimal spent-fuel-withdrawal patterns under various end-use scenarios. End-use scenarios include no-economic- return throwaway and uranium recycle with and without plutonium recycle. Results from developing, analyzing, and solving a spent-fuel-withdrawal model are used to recommend specific strategies. The spent-fuel-withdrawal problem involves the interaction of spent-fuel generation, time and capacity-dependent reprocessing demand, and expected spent-fuel value. Spent-fuel characteristics based upon burnup history and initial composition, are considered along with uranium, separative work, and storage cost projections to realize profitable spent-fuel disposition. Application of the spent-fuel-withdrawal model is done on a per-reactor basis. Assumptions inherent in the application of the model developed include, 1) unconstrained on-site storage capacity, 2) realizable uranium and plutonium values, and 3) capacity constrained reprocessing demand. Examining supply, demand, and characteristics of spent-fuel during a twenty-year horizon, the model application is developed through, 1) a dynamic programming approach, 2) a Hitchcock problem to be solved similarly to a minimum-cost-flow problem, and 3) a linear program definable as a Transportation problem. In the model analyses, the dynamic programming formulation proved to be computationally infeasible. The analyses of the Hitchcock and linear program problem is done by the use of the Out-Of-Kilter Algorithm and the proprietary mathematical MPS-III system, respectfully. Specific results indicate that the economically optimal withdrawal pattern is: 1) for uranium and plutonium recycle, a Last-In-First-Out pattern, and 2) for uranium recycle only, no discernible pattern. / Master of Science

Musk thistle (Carduus nutans) seed production from early developing (terminal and first lateral) heads was reduced by 10% in 1973 and 75% in 1974 due to larval feeding of Rhinocyllus conicus. This was caused by heavy infestation of the early heads (45% in 1973, 70% in 1974) with a subsequent 5-fold increase in the number of weevil pupation chambers in these heads. Total seed production was reduced by 35-36% in both years despite increased plant vigor due to better growing conditions in 1974. Larval feeding reduced viability of mature musk thistle seeds. Plumeless thistle (C. acanthoides) seed production from early heads decreased only 5% in 1973 and 4% in 1974 due to low rates of infestation (9% in 1973, 5% in 1974). Total seed production was reduced 0.2% in 1973 and 0.1% in 1974. Weevil larvae developing in plumeless thistle heads were more heavily parasitized than those in musk thistles. Parasitoids suffered high mortality due to entrapment in weevil pupation chambers (Aliolus curculionis, 837; Bracon mellitor, 10%), and did not inhibit weevil population buildup. These combined factors resulted in successful control of musk thistle at 1 Virginia site. R. conicus showed ovipositional preference for C. nutans over C. acanthoides heads both in the laboratory and under field conditions. Oviposition of an established weevil colony was better synchronized with musk than with plumeless thistles at a site where both thistles were present. Sequentially released, overwintered R. conicus were better synchronized with Carduus thistle development because of an extended ovipositional period, but the weevils suffered reduced fecundity. Ovipositional preference was for the earlier stages of musk thistle heads. Intermediate stages of plumeless thistle heads were preferred, and larval survival was reduced because of insufficient time for weevil development and subsequent depletion of food supply. Musk thistles subjected to mechanical and R. conicus-induced damage to terminal heads were shorter than control plants and suffered reduced seed production from terminal heads. Total head and seed production per thistle were not significantly reduced. Emerging adult weevils decreased in weight relative to crowding; no difference was detected between sexes (female, 13.4mg; male, 13.8mg). / Ph. D.