Ph. D.

Thirty-one Dorset (D), 24 Finnish Landrace (F), 35 Barbados Blackbelly x Dorset (BD), 10 Dorset x Finn (F), 24 Finn x Dorset (FD) and 35 grade Rambouillet (R) ewes were exposed to rams in various seasons. Ewes were born in 1979 or 1980; no R ewes were born in 1980. Ewes were bred in April, 1980 (APR80); November, 1980 (NOV80); August, 1981 (AUG81); May, 1982 (MAY82); and April, 1983 (APR83). Ewes born in 1980 entered the study in NOV80. The analytical model used to describe ewe performance included effects of ewe birth year (EBY), breed/EBY, season/EBY, breed x season/EBY and ewe (random). / Master of Science

The results of deoxyribonucleic acid homology experiments with the type strains of Azospirillum lipoferum, Azospirillum brasilense, and Azospirillum amazonense, and 19 additional strains of A. amazonense, confirmed that A. amazonense is a distinct new species. The description of the genus Azospirillum is emended to accommodate A. amazonense. Ribosomal RNA (rRNA) homology studies indicated 90 to 96% homology between Azospirillum lipoferum and Azospirillum brasilense, and 64 to 70% homology between these species and Azospirillum amazonense. This supports the inclusion of these three species in the genus Azospirillum. In contrast, "Azospirillum seropedicae" had very little homology with the other Azospirillum species (<22% RNA homology) and should not be considered a member of the genus. The taxonomic placement of "A. seropedicae" is uncertain. The nearest relatives of the genus Azospirillum were Aquaspirillum itersonii and Rhodospirillum rubrum (>65% RNA homology); Gluconobacter oxydans and Beijerinckia indica exhibited 30 to 60% RNA homology with Azospirillum species. Deoxyribonucleic acid (DNA) studies indicated that Conglomeromonas largomobilis subsp. largomobilis was related to Azospirillum lipoferum by >45% DNA homology and by 99% RNA homology; moreover, it was found to be a microaerophilic nitrogen fixer. Thus C. largomobilis subsp. largomobilis is a subjective synonym of A. lipoferum. In contrast, DNA homology studies indicated that Conglomeromonas largomobilis subspecies parooensis was unrelated to C. largomobilis or A. lipoferum, or to any other species tested, and its taxonomic position is uncertain. Several strains of azospirilla which form unique star-shaped colonies were identified as A. lipoferum by DNA homology. / Master of Science

Two methods of designing a point classifier are discussed in this paper, one is a binary decision tree classifier based on the Fisher's linear discriminant function as a decision rule at each nonterminal node, and the other is a contextual classifier which gives each pixel the highest probability label given some substantially sized context including the pixel. Experiments were performed both on a simulated image and real images to illustrate the improvement of the classification accuracy over the conventional single-stage Bayes classifier under Gaussian distribution assumption. / Master of Science

Six fungi, Pestalotiopsis westerdijkii QM:381, Myrothecium verrucaria QM:460, Aspergillus terrus QM:72f, Chaetomium globosum QM:459, Basidiomycetes sp. QM:806, Trichoderma viride QM:6a were screened according to their ability to elaborate an extracellular enzyme system which has the highest soy fiber-degrading activity and the highest carboxymethylcellulase activity. Pestalotiopsis westerdijkii QM:481 gave the most potent extracellular enzyme system. When Pestalotiopsis westerdijkii was grown on a wheat bran medium at a temperature of 31.5°C for ten days, it elaborated the most potent extracellular enzyme system. It was found that the optimum conditions for this extracellular enzyme system, acting on soy residue for the purpose of making soy residue protein available for extraction, were pH 4.6 and 38°C. Treating one gram of soy residue, 40 ml (32 mg Nitrogen) enzyme preparation, at the optimum pH and temperature for 20 hours caused the most efficient extraction of protein. There was an increase in the amount of soluble carbohydrates, reducing sugars, glucose and galactose due to the action of enzyme on soy residue. The amount of non-protein nitrogen in the extractable fraction of soy residue after treatment with enzyme preparation or water increase with the increase of incubation time even in the presence of toluene which prevents bacterial contamination. This is probably due to the action of proteases from the soybean and enzyme preparation. In large scale experiments, when 40 ml (32 mg Nitrogen) of the enzyme preparation per gram of soy residue were used, about 60% of the soy residue protein was made available for water extraction and the yield of extractable protein in soy milk was increased by 20%. Feeding experiments using treated or untreated soy residue and soy milk showed that the treated milk contains protein of higher quality and better digestibility when compared to untreated soy milk or treated residue. The most limiting amino acid in these products is methionine. The amino acid composition of these products was very much the same. / Ph. D.

Computational fluid dynamics methods have seen an increasing role in aerodynamic analysis since their first implementation. However, there are several major limitations is these methods of analysis, especially in the area of modeling separated flow. There exists a large demand for high-fidelity experimental data for turbulence modeling validation. Virginia Tech has joined NASA in a cooperative project to design and perform an experiment in the Virginia Tech Stability Wind Tunnel with the purpose of providing a benchmark set of data for the turbulence modeling community for the flow over a three-dimensional bump. This process requires thorough risk mitigation and analysis of potential flow sensitivities. The current study investigates several aspects of the experimental design through the use of several computational fluid dynamics codes. An emphasis is given to boundary condition matching and uncertainty quantification, as well as sensitivities of the flow features to Reynolds number and inflow conditions. Solutions are computed for two different RANS turbulence models, using two different finite-volume CFD codes. Boundary layer inflow parameters are studied as well as pressure and skin friction distribution on the bump surface. The shape and extent of separation are compared for the various solutions. Pressure distributions are compared to available experimental data for two different Reynolds numbers. / Master of Science / Computational fluid dynamics (CFD) methods have seen an increasing role in engineering analysis since their first implementation. However, there are several major limitations is these methods of analysis, especially in the area of modeling of several common aerodynamic phenomena such as flow separation. This motivates the need for high fidelity experimental data to be used for validating computational models. This study is meant to support the design of an experiment being cooperatively developed by NASA and Virginia Tech to provide validation data for turbulence modeling. Computational tools can be used in the experimental design process to mitigate potential experimental risks, investigate flow sensitivities, and inform decisions about instrumentation. Here, we will use CFD solutions to identify risks associated with the current experimental design and investigate their sensitivity to incoming flow conditions and Reynolds number. Numerical error estimation and uncertainty quantification is performed. A method for matching experimental inflow conditions is proposed, validated, and implemented. CFD data is also compared to experimental data. Comparisons are also made between different models and solvers.

The sludge blinding coefficient, β, was evaluated in this experimental study, to determine if β could be used as a useful characterization parameter for sludge filterability. Fresh activated sludge, activated sludge aged at room temperature, primary sludge, alum sludge, and a calcium carbonate slurry were filtered using a Buchner funnel apparatus and varying size filter media at various pressure differentials. Particle size measurements were also performed on the above mentioned sludges using an automated particle size analyzer to examine the impact of particle size and size distribution on β. Effects of conditioning, elutriation, supernatant removal, and replacement on β were also studied. In general, β correlated well with the average specific resistance, indicating that it could be useful in predicting a sludge filtration pattern. β was found to increase as the mean particle size of a sludge decreased, or the particle size distribution of a sludge widened. Conditioning, elutriation, supernatant removal, and replacement were found to reduce β by improving the mean particle size of a sludge and narrowing a sludge particle size distribution. In addition, β was found to increase by the applied pressure differential and filter media pore sizes for a few sludges. / Master of Science

The vorticity shedding characteristics in attached and separated regions were investigated over three configurations, namely a backward facing circular arc, an ellipse at an angle of attack and a pitching airfoil. A fully automated data acquisition system was developed, including a two-component Laser-Velocimetry system in backscatter mode, an accurately controlled traversing mechanism and a MINK-11 minicomputer. Two-component velocity measurements were obtained over the above mentioned bodies, with steady and unsteady free streams. Emphasis was concentrated on the separation region, the free-shear layers and the wake downstream of these bodies. Two inviscid vortex models were developed to predict two different flow phenomena, namely the separated flow over a circular cylinder started impulsively from rest and propagating stall over a linear stationary cascade. / Ph. D.

An automated luminometer was designed and constructed to facilitate the investigation of reaction conditions and quantitation of the chemiluminescence observed during the oxidation of NADH by horseradish peroxidase in the presence of eosin. The luminometer design incorporates a computer controlled reagent induction system, pulse counting detector and real time display of luminescence profiles. Each of the major reaction conditions was studied individually to determine the most favorable conditions for the analytical application of this reaction. In addition, this chemiluminescent reaction was studied to determine if the luminescing species is recycled. If this were the case it would provide the first essential step necessary for the future design of a chemiluminescent probe that could be reusable or be used for continuous monitoring. During the course of this investigation it was observed that the luminescing species, eosin, was being bleached. A number of experiments were undertaken to determine the nature of the bleaching process. Those steps which suppressed the bleaching process, unfortunately, also suppressed the emission process. Despite the fact that this reaction does not appear to recycle the luminescing species, it does provide a chemiluminescent method for the determination of NADH over the range 5x10⁻⁶ M to 5x10⁻⁴ M. This chemiluminescent reaction has also been coupled to several enzyme systems, which reduce NAD⁺ to NADH, in order to obtain a chemiluminescent signal proportional to the substrate concentration. / Ph. D.

Elastic scattering data was successfully taken using the new "Clamshell" spectrometer. Angular distributions of elastic differential cross sections were obtained at 50 MeV and 65 MeV using positive and negative pions scattered from ⁵⁶Ni, ⁶⁰Ni, and ⁶⁴Ni. The data were compared to predictions made using the MSU optical potential, The π⁺ data agreed fairly well with the predictions at both 50 MeV and 65 MeV while the corresponding π⁻ data significantly disagreed with the predictions. The absorption parameters in the MSU potential were varied in an attempt to fit the data. A suitable fit was achieved for both π⁺ and π⁻ data at 50 MeV and 65 MeV. The real part of the p-wave absorption parameter was well determined but showed two distinct values for π⁺ and π⁻ indicating that there is a separate potential for π⁺ and π⁻ or that the absorption part of the potential is inadequately formulated. / Ph. D.