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

The synthesis of several dihydrofurans of type 179 was accomplished by the flash vacuum pyrolysis of vinyloxiranes of type 178 obtained from the addition of the dienolate of ethyl-2-bromocrotonate (177) to various aldehydes (176). Thus, dihydrofurans were prepared from aldehydes in an overall intermolecular [2+3] dihydrofuran annulation. / Master of Science

Parametric surface representations such as the B-spline and Bezier geometries are widely used among the aerospace, automobile, and shipbuilding industries. These surfaces have proven to be very advantageous for defining and combining primitive geometries to form complex models. However, the task of finding the intersection curve between two surfaces has remained a difficult one. Presently, most of the research done in this area has resulted in various subdivision techniques. These subdivision techniques are based on approximations of the surface using planar polygons. This thesis presents an analytical approach to the intersection problem. The approach taken is to approximate the B-spline surface using subsets such as the ruled surface. Once the B-spline surface has been simplified, elimination techniques which solve for the surface variables can be used to analytically determine the intersection curve between two B-spline surfaces. / Master of Science

With the increasing need for large columnless structures in today's society, glued-laminated Triax domes are being designed and built. Even though many have already been constructed, no methods have been established to accurately determine the ultimate load capacity or the factor of safety. Several ABAQUS finite element analyses have been conducted at Virginia Polytechnic Institute and State University to determine these values (Davalos, 1989). The work in this area has been slowed due to the absence of a preprocessor for the creation of the input data file. The use of a preprocessor could greatly accelerate the analysis process and prove to be more efficient. The primary objective of this thesis is to present a clear detailed procedure for the creation of the input data file using the Integrated Design Engineering Analysis Software package (I-DEAS) version 4.1. In addition to meeting this objective, several other topics concerning I-DEAS modeling guidelines and post processing features are discussed. The results oT a linear finite element analysis is also presented. The use of a preprocessor is essential for the creation of the triax input data fiIe. I-DEAS can not only meet this challenge, but can provide assistance in all facets of finite element modeling. / Master of Science

Recent developments in the philosophy of structural steel design have led to design specifications that incorporate second-order geometric effects. The use of second-order elastic analysis (SOEA) in the design of structural frameworks may lead to more economically designed structures and increased knowledge of structural stability. The research presented here concerns economy of design between the available steel design specifications as they apply to the metal building industry. Since these buildings are primarily for industrial use, their optimization suggests the use of gabled rigid frames with tapered elements to provide the required load carrying capacity. Results of the research indicate that elastic stability considering geometric nonlinearity is not a primary concern for these types of frames. Rather, the fully-stressed design approach leads to the optimally designed frame. / Master of Science