The dependence of an airfoil stall behavior upon the acoustic l environment was experimentally investigated at a Reynolds number of 200,000. The Wortmann FX-63-137-ESM airfoil section was used for the model with an aspect ratio of 4. Some acoustic disturbances could alter the transition process in the shear layer of the separation bubble on the upper surface of the airfoil. These disturbances could delay the deep leading edge stall or hasten stall recovery in some cases. A good agreement was found with the Crabtree criterion to predict the leading edge stall. / Master of Science

Parallel robotic manipulators are generally believed to be stiffer under load and more precise than conventional serial manipulators. This is because of their closed loop construction which allows forces to be shared through multiple paths to the ground. Unfortunately, most proposed parallel manipulator designs have severe workspace restrictions. The introduction of Variable Geometry Trusses (VGT’s) represents an opportunity to overcome this limitation. The lack of stiffness in many serial manipulators is primarily due to compliance at the joints. The disadvantage of the series connected device include limitations in lilting capacity and vibration problems. Difficulties of this sort result from the cantilever structure of the device. These factors often limit the degrees of freedom that can be provided in the serial configuration. By replacing the revolute joints with the ‘VGT joints’, it may be possible to add considerable rigidity at the joints and hence design a highly dextrous manipulator. The objective of this thesis is to study the feasibility of a design of manipulators using Variable Geometry Trusses. A modeling scheme capable of solving the inverse problem in closed form and finding the range of all possible solutions for a planar VGT has been presented. Another aspect that has been dealt with is in utilizing the extra degree of freedom that becomes available in the proposed manipulator. Enhancing the performance of the manipulator by optimizing relevant parameters has been carried out for a demonstrative case involving a planar truss. / Master of Science

The resin transfer molding (RTM) process has been identified as a cost-effective fabrication technique for producing composite materials from geometrically complex reinforcements. Processing models can be used to determine the temperature and pressure cycles which will produce a finished part with the best properties in the shortest time. This work involved the development and verification of a processing model for RTM. The processing model is based on the assumption that infiltration can be described as flow through a porous medium. Flow through porous media, as governed by D’Arcy’s law, depends on the viscosity of the fluid and the microstructure of the interconnected pores. Infiltration by thermosetting resin systems is assumed to behave as a Newtonian fluid with a time and temperature dependent viscosity. The kinetics of the resin can be described by mathematical expressions determined from standard thermal analysis techniques. The reinforcement is assumed to be a homogenous, anisotropic material which exhibits strain stiffening, hysteresis and plastic deformation. D’Arcy’s law describes the porous material in terms of the material permeability. Kozeny-Carman’s relationship is used to relate the porosity to the permeability. Solution of D’Arcy’s law is accomplished in a quasi-steady state manner by an evolving mesh finite element technique. After infiltration is completed, the model continues to predict the temperature, degree of cure and viscosity of the resin. The equations governing the unsteady heat transfer are solved with an existing cure model by the finite difference method. Results of the processing model include estimates of infiltration, gel and cure times as well as the cured thickness and fiber volume fraction. Test laminates were fabricated, mechanically tested, and compared to prepregged laminate results. Construction of one of the test laminates was simulated with the processing model to verify the accuracy of the simulation. / Master of Science

The objective of the study was to develop a modeling technique to idealize thin, orthotropic plates into an equivalent grid, suitable for the matrix-displacement method of analysis. The formulation is an alternative to the classical plate theory and finite element method. The grid model is unique compared to other grid formulations in its applicability to plates exhibiting material orthotropy in addition to isotropy and shape orthotropy. Further, the grid model has less members compared to the previous grid formulations. A function was developed to establish the grid member cross-sectional size for various boundary conditions and material properties. The maximum error between predicted and published theoretical and experimental deflections was 3% for plates in isotropic and advanced composite materials. The maximum error between predicted and experimental deflections for wood based composite plates was 20%. / Master of Science

The minimum T-XCO₂ location of the reaction boundary calcite + quartz + rutile = sphene + CO₂ has been experimentally determined in H₂0-CO₂-NaCl fluids at 2 kbar. Extent and direction of reaction were monitored by the CO₂ weight change method using natural materials. All bulk compositions contain 23 wt. % NaCI, relative to NaCl-H₂0. Synthetic fluid inclusions trapped at the T-XCO₂ conditions of several points along the curve suggest unmixing of the fluid phase, as evidenced by coexisting CO₂ vapor-rich and aqueous, halite-bearing inclusions. Results from 450-520 °C are listed below. / Master of Science

A house is a place of solitude, refuge dnd intimacy. A winery is a place of meeting, time and vulnerability. This thesis integrates the public realms of a winery and the private domain of a house using concrete walls as barriers, boundaries and structure. / Master of Architecture

In a pilot study, response times of 64 possible chords on the Ternary Chord Keyboard (TCK) were compared in order to establish a basis for assigning characters to chords. It was found that subjects had faster response times for some chords than others. Upon close inspection of the experimental procedure, it appeared that the way in which the chords were cued caused part of the differences in response time, which had been expected to depend only on chord motor differences. The present study was designed to examine the hypotheses that chord cueing caused part of the differences in chord response times, and that this effect of cueing is consistent over practice; and also the hypothesis that the results of the pilot study reflected the motor (movement time) difference between chords, and that the difference itself is consistent over practice. This was done in the framework of Sternbcrg's Additive Factors Method. lt was found that the cueing scheme used in the pilot study did not cause the differences in chord response times. However, the differences in chord movement time was not reflected by the use of the pilot study paradigm. This technique should therefore not be used in ordering chords according to chord case. / Master of Science

Microbial populations from subsurface soil collected from a hydrocarbon contaminated site and a pristine site with no history of contamination had the ability to degrade pentachlorophenol (PCP) in anaerobic enrichment cultures. Increasing concentrations of PCP in nitrate, sulfate and yeast extract-mineral salts media were used to acclimate the cultures. Nitrate enrichments, previously incubated in an anaerobic phenol-mineral salts medium, showed 23% degradation in medium containing 40 μg ml⁻¹ PCP during a 32 d incubation period. Cultures not adapted to phenol degradation did not degrade PCP at concentrations over 20 μg ml⁻¹. Enrichment cultures grown in the anaerobic yeast extract-mineral salts medium did not degrade PCP at concentrations over 20 μg ml⁻¹ and phenol adaptation did not enhance PCP degradation. The sulfate reducing enrichment containing 1 μg ml⁻¹ PCP showed 71.3% degradation after 32 d incubation. No degradation occurred at or above 5 μg ml⁻¹ PCP. PCP intermediates, 2,4,6-trichlorophenol (TCP) and 3,4,5 TCP were found in the spent culture of the nitrate reducing enrichment. In the spent culture of the sulfate reducing enrichment, 3,4,5 TCP and 2,3,4,5-tetrachlorophenol were found. Attempts to obtain a pure culture of an anaerobic PCP degrading bacterium were unsuccessful. / Master of Science

This work deals with the melt blend of 60/40 PHB/PET (p-hydroxybenzoic acid and polyethylene terephthalate) and 80/20 PHB/PET copolyesters in a 50:50 weight% ratio. Specifically, the interest was to determine as to how do the mechanical properties of the injection-molded parts from the blend compare with that of 70/30 PHB/PET composition and to find out if the melt blend obtained after a single extrusion pass represents an equilibrium composition blend. To determine the anisotropic mechanical properties, injection-molded plaques were obtained by injection-molding the blend at different temperatures. It was found that the tensile properties (tensile strength, modulus and elongation at break in the machine direction) of the blend increase with the increase in the injection-molding temperature (from 300 to 320°c) and then decrease. The flexural modulus of the injection-molded plaques (at an injection-molding temperature of 330°c) of a 50:50 blend of 60/40 PHB/PET and 80/20 PHB/PET mixed only in the injection-molded unit was 2.2 x 10⁶ psi which is 40% higher than that reported for the 60/40 PHB/PET, 100% higher than reported for either 80/20 PHB/PET or 70/30 PHB/PET. To determine the equilibrium nature of the blend, samples with different residence time in the extruder and the 70/30 PHB/PET samples were analyzed by means of Differential Scanning Calorimeter (DSC), Dynamic Mechanical Analysis (DMA), Thermal Mechanical Analysis (TMA), Scanning Electron Microscope (SEM) and Rheometrics Mechanical Spectrometer (RMS), and the mechanical properties of the injection-molded plaques were also determined. The DSC thermogram of the four extrusion pass blend showed multiple melting endotherms. Similar behavior was observed for a number of samples which had been annealed above the melt temperatures for different lengths of time. The formation of multiple peaks was attributed to the incomplete transesterification reaction in the extruder. The OMA results also indicated a substantial decrease in the melting temperatures with the increase in the number of extruder passes. A similar decrease in the melting temperatures has been reported in the literature for various polyesters undergoing transesterification reaction. The TMA results showed that the modulus versus temperature profiles (softening profiles) of one, two and three extrusion pass samples were the same but that of the four extrusion pass film was different and was closer to the softening profile of the 70/30 PHB/PET film. The softening profile of the four extrusion pass sample indicated the presence of crystallites of varying degrees of development, which corresponds well with the splitting peak phenomenon observed in the corresponding DSC thermograms. Thus, it is clear that a chemical reaction is occurring in the extruder. It is suspected that the observed decrease in the flexural properties with the increase in the number of extruder passes is due the transesterification reaction occurring in the extruder. Transesterification studies were also carried out in a cone & plate geometry in the RMS in a no-shear (simple melt annealing) and shearing environment on a larger time scale. From a comparison of the thermal behavior of the blend (as a function of the reaction time) in different environments, it was concluded that the transesterification reaction proceeds faster in the presence of deformation such as occurs in the extruder or in a simple shear flow and with an increase in temperature. Finally, to compare the rheological properties of the multiple extrusion pass and the 70/30 PHB/ PET samples, dynamic frequency sweeps were performed in the RMS at different temperatures. At a given frequency, the complex viscosity, storage modulus and loss modulus increased with an increase in the number of extrusion passes. This increase is unexpected. A number of explanations have been proposed to account for this increase in the rheological properties. / Master of Science

The aging phenomena is a process to which all organisms eventually succumb. The universality of this phenomena suggests that there may be one overwhelming factor involved. The exact biochemical basis of aging is still unclear. Free radicals such as the superoxide radical (O₂⁻) and the hydroxyl radical (OH⁻), formed in biological oxidation reactions may be responsible for cellular aging. Because of the high reactivity of the O₂⁻ and the OH⁻ they can produce extensive damage to lipids, proteins, and nucleic acids. In this study we have developed an <i>in vitro</i> quiescent model using density dependent bovine embryonic lung fibroblast (BELF). The effect of this process on the antioxidant defense enzymes such as, the superoxide dismutases, catalase, glutathione reductase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase, was studied. We have also extensively monitored the levels of free radical in the cell by both direct and indirect methods. The results indicate that no significant (p<0.05) changes in the activity of any of the major antioxidant enzymes in our quiescent model. Significant increases were observed in the intracellular levels of lipofuscin (age pigment) with time, but no changes in the generation of free radicals were observed using electron spin resonance spectrometry, cytochrome <i>c</i> reduction or spectrofluorometric techniques (caution should be placed in statistical interpretation of the data because of the small sample size in some experiments). The transcriptional and translational controls of the one of the major antioxidant defense enzymes (manganese superoxide dismutase) in bovine embryonic lung fibroblasts, human pulmonary artery endothelial cells (HPAE) and bovine PAE cell lines were also studied. Our preliminary data suggest that inhibitors of protein and RNA synthesis both cause a significant decrease in the induction of the manganese SOD in bovine pulmonary endothelial cells. / Master of Science