Fuel stocks today contain a large percentage of sulfur, nitrogen, and metals. To meet processing and environmental regulations, these components must be removed. Hydrodesulfurization reactions and the use of catalysts to enhance this process have been under extensive study in recent years. The main hydrodesulfurization catalyst used has been cobalt-molybdenum on an alumina support. This study investigated rhodium incorporated zeolites as catalysts for thiophene hydrodesulfurization reactions. The compounds RhCl₃ • 3H₂O, Rh₂(CO₂CH₃)₄, and Rh(PPh₃)₃Cl were adsorbed onto 13X and ZSM5 zeolites. Results of thiophene hydrodesulfurization over RhCl₃-13X and RhCl₃-ZSM5 were compared to those of commercial Co-Mo/Al₂O₃ to determine the most active catalyst under different experimental conditions. X-ray photoelectron spectroscopy, infrared spectroscopy, x-ray diffraction and microelectrophoresis were used to characterize the zeolites. Hydrodesulfurization reactions were carried out in a pulse microreactor/gas chromatograph system as a function of gas flow rate and reaction temperature. Reaction products were identified by mass spectrometry. RhCl₃-13X exhibited maximum thiophene conversion when presulfided with thiophene injections at 100°C, or with a 10 vol% H₂S/90 vol% H₂ gas mixture at 400°C. At a H₂S-sulfiding temperature of 250°C, the commercial Co-Mo/Al₂O₃ catalyst was most active. Over all catalysts, the only reaction products were hydrogen sulfide, butene and butane. The butene/butane product ratio increased with increasing temperature. On the basis of these results and XPS measurements, Rh(I) was identified as the active hydrodesulfurization species. / Master of Science

The initial portion of this thesis examines the problem of tracking a maneuvering target in the 2-dimensional (X,Z) plane, vertical to the ocean floor, using passive time-delay measurements. The target is free to maneuver in velocity and make depth changes at times unknown to the observer. In the past, tracking systems have used Extended Kalman Filters to process the nonlinear measurements, but these have inherent divergence problems. To overcome this, a nonlinear prefilter is added to linearize the measurements and thus allow the use of a conventional Kalman Filter which makes the tracking system more 'robust' and also decouples the depth estimator from the polar range estimator. The depth estimator is discussed in detail here. The latter part of this thesis introduces tracking in the 2-dimensional horizontal (X, Y) plane, parallel to the ocean floor, to observe polar range and target bearing angle. The approach of using a nonlinear prefilter and a standard Kalman Filter is similar to the one described above. Subsequently, the analysis is extended to a Kalman Filter which is not 'matched', i.e. it does not possess any knowledge of the deterministic inputs which cause target motion. This necessitates the use of a bank of Kalman Filters and an adaptive weighting scheme. Test results are included to show that all source maneuvers can be tracked with a relatively high degree of accuracy. / Master of Science

Clean laboratory technology and pure culture techniques were combined to determine the effect of ectomycorrhizae on the uptake of lead by Pinus sylvestris L. seedlings. By culturing the ectomycorrhizal fungus, Pisolithus tinctorius (Pers.) Coker and Couch, in liquid Hagem's medium with different concentrations of lead (0, 50, 250 and 500 ng/g sol), it was determined that the fungus readily takes up lead from such and aqueous medium. It was also determined that the pH of the medium controls the amount of lead in solution that can be taken up by the fungus. A series of growth studies where Pisolithus was cultured on Hagem's agar indicated that the growth of the fungus is reduced when the lead concentration in the medium is approximately 25 ug/g sol. It was estimated that a lead concentration of approximately 1,000 ug/g sol may completely inhibit the growth of the fungus. Furthermore, it was determined that the acetate ion is inhibitory to the growth of Pisolithus. By culturing mycorrhizal and non-mycorrhizal seedlings of P. sylvestris and analyzing the seedlings' roots, stems and leaves for their lead concentrations, it was determined that ectomycorrhizae facilitate the uptake of lead. Ectomycorrhizal roots can take up more lead from a vermiculite/hydroponic solution mixture because of their greater surface area and exploration of vermiculite surfaces as well as their increased production of lead solubilizing acids. This additional lead found in mycorrhizal roots, however, does not appear to be translocated to the above ground portions of the seedlings. This increased uptake of lead by mycorrhizal roots is expected to take place in natural soil systems as well. / Master of Science

The flotation of chalcopyrite and sphalerite has been accomplished without the use of collectors. Of the six chalcopyrite ores tested in the present work, some floated well using only a frother, while others required the addition of sodium sulfide, presumably to remove the hydrophilic surface oxidation products. On the other hand, the flotation of sphalerite ores was found to require both sodium sulfide treatment and copper-activation. The ratio of these two reagents was most critical, the optimum Cu²⁺/S²⁻ atomic ratio being approximately 0.17 over a wide range of reagent dosages. Potential measurements taken during both batch and micro-flotation experiments demonstrated that the collectorless flotation of chalcopyrite was possible only in oxidizing conditions, which confirms an earlier finding by Heyes and Trahar (1977). In relation to this phenomenon, three possible mechanisms have been discussed: i) elemental sulfur formed under oxidizing conditions is responsible for the collectorless flotation, ii) polysulfide ions formed during the incipient surface oxidation process render the mineral hydrophobic, and iii) HS⁻ ions, which may render the mineral hydrophilic upon adsorption, are removed from the system under oxidizing conditions. The first mechanism may operate primarily in acidic solutions, while the second mechanism operates in alkaline solutions where elemental sulfur is thermodynamically unstable. The third mechanism is based on the assumption that a clean, unoxidized surface is inherently hydrophobic. Spectroscopic evidence has been presented to support these proposed mechanisms. / Master of Science

no abstract provided by author / Master of Architecture

An analytical and experimental study was done to determine the effect of entrainment on the heat transfer to a single, plane, turbulent impinging jet. Solutions to the momentum and energy equations were obtained with similarity and series analyses. The analytical model is compared with measured heat transfer rates to single air jets impinging normally on an isothermal heated surface. To determine the effect of entrainment, the temperature of the environment surrounding the jet was varied between the initial temperature of the jet and the plate temperature. Results obtained for jet arrays show that entrainment of air in the recirculation region between the jets can significantly affect the heat transfer rates. Comparison of the analytical model to the measured heat transfer rates for jet arrays shows that the single jet model can be successfully applied to jet arrays when the effect of entrainment is considered. / Master of Science

This thesis examines the effects of marriage and childbirth on industrial sector location of women in a longitudinal analysis, using the National Longitudinal survey of Labor Market Experience, Young Women File for years 1968 to 1975. Contrary to theoretical assumptions, women, regardless of marital or parental status are found in the same proportions in the monopoly and competitive sectors. Although marriage and childbirth appear not to have any effects on the labor market segmentation of women, the labor markets are remarkably stable. Suggestions for future research and an assessment of labor market segmentation theory are given. / Master of Science

In materials evaluation applications requiring the interrogation of modified far field patterns of an ultrasonic transducer, it is desirable to use a transducer which produces a beam with a Gaussian profile. A transducer with a velocity profile which is Gaussian as a function of radius and independent of angle is described. The transducer has been constructed by depositing a circularly symmetric metallic multiple electrode array on a 12. 7 mm diameter x-cut quartz disk. Each electrode is independently connected to an impedance network optimized to produce the Gaussian distribution with less than two percent maximum error. A computer aided electrode design and normalized three dimensional ultrasonic measurements of the far field distribution are presented. / Master of Science

To determine the energy saving potential available from recirculating air in peanut drying, a thin layer drying simulation model was adapted to incorporate recirculation. A heat and mass balance computer model was developed to enable the determination of heat energy input. Laboratory crop dryers were designed and constructed to conduct experiments to verify the simulation models. Five batches of peanuts were dried using different recirculation strategies and the model successfully predicted the experimental results, including moisture content and wet and dry bulb temperatures. Energy savings of up to 20 percent were realized in the experimental runs. The simulation model was also used to evaluate and compare several recirculation strategies in order to determine successful strategies. / Master of Science

Successful architecture responds to user function on one level and its environment on another. A design for graduate student housing that operates on both levels is shown. The potential of curved building masses is explored. The structure for housing is the structure for parking, and the whole complex defines and separates vehicular and pedestrian circulation. Existing features of the site are employed and enhanced to create a tie between the old and new. The spaces are as important as the space makers. / Master of Architecture