The harmonic excitation of simply supported Euler plates is performed experimentally using arrays of piezoceramic patch pair actuators bonded to the plate surface. The experimental techniques used are presented, and the effects of patch location, relative actuator phasing, and excitation frequency on modal excitation are demonstrated. In addition, experimental results are compared to a previously developed closed-form solution which predicts the modal distribution due to such excitation. Finally, a finite element model of a simpler 2-D case of beam actuation is employed to illustrate the effects of the adhesive layers between the patches and structure on modal excitation. Results show that the closed-form solution is capable of predicting both the relative modal distribution and absolute modal amplitudes for different experimental configurations and indicate that with knowledge of the system resonant frequencies and nodal lines, experimental parameters such as excitation frequency, patch location, and relative patch phasing can be logically manipulated to produce a desired vibrational response. The results of the finite element analysis reveal that the net effect of the finite adhesive layer depends on both the stiffness and thickness of the layer, and that increasing either of these parameters can result in multiple consequences, which can combine to positively or negatively affect modal excitation levels. / Master of Science

The purpose of this thesis was a) to review the design process literature in architecture and urban planning, b) to develop a model of the interior design process, and c) to apply parts of the model in a case study. The genesis and evolution of design processes in fields allied with interior design was traced. The review of literature established that interior design has little documentation of the design process. Much of what exists is borrowed from architecture and urban planning. / Master of Science

Shape memory alloys (SMA) have the unique ability to recover large strains and generate large recovery stresses via a repeatable martensitic transformation. Stress-strain and shape memory effect characteristics are needed in order to develop SMA force actuator design methods. Moreover, constitutive models able to quantitatively predict these characteristics and thus be useful as engineering design tools are also needed. An experimental apparatus designed to characterize the mechanical behavior of SMA was built and utilized. The apparatus is used specifically to gather stress-strain and shape memory effect characteristics from nitinol wire whereby mechanical properties associated with the material are determined. Phenomena such as the R-phase and stress induced martensite serration are investigated. A one-dimensional constitutive model is presented that quantitatively predicts stress-strain and shape memory effect behavior and was developed with the intention of being an engineering design tool for SMA force actuators. Experimental stress-strain and shape memory effect results are compared against that predicted by the model with the intention of verifying the model. The model displays the ability to predict stress-strain behavior that is in good quantitative agreement with experiment. The model also displays the ability to predict hysteric shape memory effect behavior for free, controlled, and restrained recovery cases of selected prestrains that is in good quantitative agreement with experiment. The model is unable to predict shape memory effect behavior such as the R-phase. Demonstrating the ability to experimentally investigate a constitutive model will hopefully inspire further combined experimental and theoretical SMA research. / Master of Science

The responses of larval fish to toxicants in subchronic toxicity tests may be modified by events and stressors not associated with the toxicants themselves. In the following work, three potential modifying factors related to larval fish growth, survival, and response to toxicant stress were investigated. Using four-day acute cadmium toxicity tests and seven-day subchronic toxicity tests, differences in the responses of larvae based on the age of the larvae, their exposure to methylene blue, and changes in environmental pH were determined. The age of larvae chosen for toxicity tests, 1 to 24 h old, 24 to 48 h, or 48 to 72 h, did not significantly affect the cadmium (Cd) LC_50S in acute tests or the larval growth or survival in subchronic tests. Prior methylene blue (MB) exposure in larval fish was. not found to affect the Cd LC₅₀ compared to unexposed larvae. However, in subchronic tests with industrial effluents, prior MB exposure resulted in lowered survival or lowered growth, but did not increase sensitivity to the effluent. Lowered growth and survival was observed in blue- dyed individuals from larval populations exposed to MB during the interval from hatch to test commencement. At 20°C, the acute toxicity of MB, as indicated by the LC_10S, was apparent at concentrations greater than 44 mg MB/L in 24 h. At the suggested fathead minnow culture temperature, 25°C, concentrations greater than 5.0 ppm were acutely toxic in 96 h. Chronic toxicity, determined at 25°C, was found at levels greater than 2.12 mg MB/L. Light intensity negatively affected MB chronic toxicity. Chronic values estimated by larval fish growth response were significantly lower in the test done under normal lab light compared to that done under very subdued light. Larval fathead minnows were sensitive to low pH stress based on the acid used to lower test solution pH. Hydrochloric acid was found least toxic to larvae at low PH; phosphoric acid was found most toxic. Larvae tolerated instantaneous changes in pH 2.0 units lower and 1.5 units higher than their culture water without any significant decrease in growth and survival as measured in 7 d. These results indicate that the pH tolerance range for larval fathead minnows, where no effects are seen on growth or survival, is greater than pH 6.0 and less than pH 9.5. / Master of Science

Lactating cows with cannulae in the rumen and proximal duodenum were used in two 4 X 4 Latin square experiments to evaluate biohydrogenation, flow rates, and digestibility of dietary fatty acids in the gastrointestinal tract. In the first experiment, four cows were fed diets with 0% supplemental fat, 3% tallow, 3% partially hydrogenated tallow, or 3% tallow coated with casein and corn syrup solids. Fatty acid intake and flow to the duodenum increased with fat supplementation. Total tract apparent fatty acid digestibility was reduced by partially hydrogenated tallow. Apparent digestibility of C_18:0 in the small intestine quadradically decreased (R²=.86) as C_18:0 flow to the intestine increased. Fat supplementation increased milk production and decreased milk protein percent but did not affect milk fat percent or 3.5% FCM. Fat supplementation increased C_18:0 and C_18:1 and lowered C_12:0 and C_14:0 concentrations in milk fat. In the second experiment, four lactating Holstein cows were fed diets with 0% supplemental fat, 3% partially hydrogenated fatty acids, 1.5% fish oil plus 1.5% stearic acid, or 1.5% soybean oil plus 1.5% partially hydrogenated soybean oil. Fish oil decreased DM intake. Fish oil and soybean oil reduced biohydrogenation of C_18:1 + C_18:2 + C_18:3 in the rumen from 65% (control) to 28% and 55%, respectively, and increased trans C_18:1 flow from the rumen 4-fold. Milk fat percent was decreased by fish oil and soybean oil. Milk fat percent across treatments linearly decreased with amount (g/d) of trans C_18:1 flowing to the duodenum (R²=.92) and percent trans C_18:1 in milk fat (R²=.94). / Master of Science

Delineations of Applinq, Cecil, and Davidson soils were sampled on a grid pattern (4 to 9 m spacings), using a bucket auger, to determine their modal character and variability with regard to various chemical and morphological parameters. Delineations were located on south-southwest facing, 5 to 12% slopes, in gently rolling landscapes that typify the Virginia Piedmont. Appling soils had the thickest A horizons and sola and were highest in A horizon P but were lowest in A horizon pH, K, Ca, Mg, and organic matter and B horizon pH, P, K, Ca, and Mg. Cecil soils were highest in A and B horizon pH and in B horizon P, K, and Mg, but had the thinnest sola. Davidson soils were highest in A and B horizon Ca and in A horizon organic matter but were lowest in A horizon P. Soil variability was considerable at all sites, with A horizon thickness and pH and B horizon P and K varying the most over short distances. Subsequent to the grid sampling study, we dug soil pits in areas in which approximately modal soil characteristics had been observed. pit studies revealed negative effects of agriculture upon these soils; A horizons were high in clay, had high bulk densities, and had low organic matter contents. Predictably, tilth was poor. pit studies also showed that locally supplied colluvial materials cover a significant portion of the upland Piedmont soilscape. Of 18 pedons studied, 12 appeared to be formed in colluvial materials. However, colluvium-derived soils were usually distinguished from their residual counterparts only by the presence of a stone line that roughly paralleled the present soil surface at depths of 0 to 2 m. Therefore, these colluvial inclusions should rarely affect soil interpretations for Appling, Cecil, and Davidson map units. / Master of Science

Ustilsgo syntherismae (Schwein.) Peck, which causes loose smut of crabgrass, infects its host systemically and destroys seed production. Greenhouse experiments were carried out to investigate the mode of infection, the disease incidence that can be obtained by artificial inoculation and the conditions necessary for optimum infection, cross-infection on southern and smooth crabgrass, and the reasons for the late observance of the disease. U. syntherismse infected southern crabgrass, Digitaria ciliaris (Retz.) Koeler, by both seed-borne and soil-borne teliospore inoculum. Disease incidence was high (84-91%) in some treatments. Higher rates of teliospore application resulted in larger percentages of smutted plants. When infesting the potting mixture, the highest percentages of smutted plants were obtained when infestation and planting were done at the same time. Earlier or later planting resulted in fewer smutted plants. When planting at various depths, greater numbers of smutted plants were obtained when inoculated seed were planted 0.5 to 1.0 cm below the surface versus planting on the surface or at greater depths. The appearance of 50% of infected plants' first panicles (in greenhouse experiments) was delayed by 4.5 weeks compared to the emergence (50%) of first panicles from healthy plants. In cross inoculation experiments, southern and smooth crabgrass plants developed smut only when inoculated with spores collected from large and smooth crabgrass~ respectively. / Master of Science

An improved method for evaluating the moderator temperature coefficient (MTC) of reactivity in pressurized water reactors based on a newly established technique is described. Previous work has correlated stochastic fluctuations in the reactor core-exit temperature with similar fluctuations in the in-core neutron flux. The frequency response function between these two stochastic signals has been shown to be proportional to the moderator temperature coefficient. Though this method has been shown to agree well with reactor core design and measured values of the MTC, the method requires over three hours of data processed via the fast Fourier transform, and has certain limitations which suggest that the data analysis be done another way. In the present work, the multivariate autoregressive analysis method is utilized to process under ten minutes of the plant data used previously. Nearly identical results were obtained using only 5 % of the data used in the prior analysis. / Master of Science

Real-time constraints place additional limitations on distributed memory computing systems. Message passing delay variance and maximum message delay are important aspects of such systems that are often neglected by performance studies. This thesis examines the performance of the spanning bus hypercube, dual bus hypercube, and torus topologies to understand their desirable characteristics for real-time systems. FIFO, TDM, and token passing link access protocols and several queueing priorities are studied to measure their effect on the system’s performance. Finally, the contribution of the message parameters to the overall system delay is discussed. Existing analytic models are extended to study delay variance and maximum delay in addition to mean delay. These models separate the effects of node and link congestion, and thus provide a more accurate method for studying multicomputer networks. The SLAM simulation language substantiates results obtained analytically for the mean and variance of message delay for the FIFO link access protocol, as well as providing a method for measuring the message delay for the other link access protocols and queueing priorities. Both analytic and simulation results for the various topologies, protocols, priorities, and message parameters are presented. / Master of Science

A study has been conducted to determine whether or not tribopolymerization can occur under conditions of fretting contact. Using a laboratory test consisting of oscillating hard steel balls loaded against flat steel or aluminum disks, effects of various monomers on friction, wear, and surface film formation were determined. Monomers, capable of polymerizing either by polycondensation or addition processes, were used at 1 % concentration in hexadecane. Under the conditions used (90N load, 65Hz frequency, 200μm peak-to-peak amplitude, 1 hour), the monomers tested reduced friction or wear or both. Fourier Transform Infrared Microscopy (FTIRM) analysis of the test specimens shows that organic material is present in the wear scar regions and depends on the metal used, the monoester structure, location on the disk, and the method of cleaning the surface after a test. With aluminum-on-steel the addition of I % styrene to hexadecane reduced the wear volume of the disk by over 650/0; furthermore, positive evidence of polystyrene was found via FTIRM. These results support the hypothesis proposed by Kajdas that addition-type tribopolymerization can be initiated by exo-electron emission. Under these conditions of expected relatively low surface temperatures, tribopolymerization does not occur with polycondensation-type compounds such as the C₃₆ dimer acid/ethylene glycol monoester. With this additive, known to be extremely effective in reducing wear at higher surface temperatures, effects on wear were small and no positive evidence of polymerization was found; however, metal soaps formed under these conditions. / Master of Science