This thesis presents a comprehensive methodology for predicting and minimising the noise radiated from a constant speed gearbox assembly by means of attaching optimally placed stiffening ribs on the casing. The procedure involves building an FE model of the gearbox, which is updated using modal parameters extracted from a modal test. This is followed by synthesis of the required FRFs with respect to the forcing degrees-of-freedom. The forces, which are assumed to act only at the bearings are identified from these FRFs and the measured operational velocities of the casing. The identified forces are then used to excite the updated FE model to re-calculate the vibration velocities. A boundary element method is used to calculate the final radiated sound power to be compared with that measured. The same forces are used later to excite the modified gearbox casing to determine the improvement given by optimised modification. The optimisation study minimises the vibration energy of the casing in 10% bands around critical frequencies, in this case the first two harmonics of the gearmesh frequency. To allow for errors in the model, the excitation is by white noise, so as to produce wide stop bands, rather than minimising the response at particular frequencies. The vibration energy is weighted for radiation efficiency, A-weighting, and relative source strength in the bands. The final optimal stiffener layout is validated through a final vibration and acoustic calculation on the updated gearbox model using the forces identified in the earlier steps. The study of one particular gearbox concludes that i) the proposed hybrid optimisation scheme produces a theoretical effective noise reduction of 3 dBA for the total sound power. ii) Because the gearmesh harmonics were targeted, a further 5 dB improvement was effectively gained by eliminating the tonal penalty which otherwise applied. iii) From plate studies it was demonstrated that the stiffening ribs could be attached using epoxy cement (to avoid welding) and that the properties of the cemented joint could be determined by model updating after attaching one rib, so as to obtain a better prediction of the final optimised result.

An in-depth study has been carried out on the reduction, softening and melting behavior of olivine based pellets in the experimental blast furnace. The aim of the project was to develop a fundamental understanding of the reduction mechanisms of olivine based pellets and to develop a correlation between the reduction rate and the softening behavior in the cohesive zone of blast furnace. The carburization characteristics of reduced iron were also investigated by examining olivine pellet and coke samples excavated and probed from an experimental blast furnace as well as the experimental investigations of pure hematite and heat treated coke. X-ray diffraction analysis was used to successfully determine the reduction degree of olivine pellets in different parts of the experimental blast furnace. These results were found to be consistent with assessments of reduction degree based on a detailed chemical analysis. The average reduction degree of iron oxide was seen to increase as the pellets descended towards lower zones of the EBF. Up to 75% reduction was completed before the pellet had reached the cohesive zone; remaining reduction was completed within the cohesive zone. Coke Lc showed a linear variation with experimental temperature above 11000C; a correlation was established to estimate furnace temperature as a function of EBF depth. The reduction degree of iron ore pellet showed a linear correlation with distance from the stock line of the EBF to the upper part of cohesive zone. But an abrupt increase in reduction rate was observed in the cohesive zone, a result observed in both EBF and experimental studies. The presence of olivine did not have much influence on the reduction degree of iron ore pellets for temperatures below 1100oC in the upper shaft zone of the EBF. However, olivine was found to increase the rate of reduction in the advanced stages of reduction in the cohesive zone for temperatures in excess of 1100oC. This effect was attributed to the formation of increased amount of molten iron oxide within the pellet. The initial melt formation and acceleration of the reduction rate in the cohesive zone of the EBF were also investigated. From the comparison between the reduction degree of excavated olivine pellets in this study and previous studies of EBF, it was found that the excavated pellets were located in the cohesive zone and increase of reduction rate in this zone could be verified by not only the change of gas composition, but also initial melt formation containing FeO phase. The chemical composition of slag phases of excavated pellet samples were located on the line between 2FeO??SiO2 and 2MgO??SiO2 in the FeO-MgO-SiO2 ternary phase diagram. This result is in good agreement with the assumption that the initial slag formation of the olivine pellets had proceeded from the fayalite and after reduction the FeO contents in the slag phase had decreased and eventually precipitated as slag with a higher melting point. From the analysis of carbon contents of the excavated pellets in cohesive zone, it was observed that the carburization of iron pellets began after the complete reduction. This study has established that the reduction rate of iron pellet is the rate controlling step for carburization irrespective of the carburization reaction by the solid carbon.

An in-depth study has been carried out on the reduction, softening and melting behavior of olivine based pellets in the experimental blast furnace. The aim of the project was to develop a fundamental understanding of the reduction mechanisms of olivine based pellets and to develop a correlation between the reduction rate and the softening behavior in the cohesive zone of blast furnace. The carburization characteristics of reduced iron were also investigated by examining olivine pellet and coke samples excavated and probed from an experimental blast furnace as well as the experimental investigations of pure hematite and heat treated coke. X-ray diffraction analysis was used to successfully determine the reduction degree of olivine pellets in different parts of the experimental blast furnace. These results were found to be consistent with assessments of reduction degree based on a detailed chemical analysis. The average reduction degree of iron oxide was seen to increase as the pellets descended towards lower zones of the EBF. Up to 75% reduction was completed before the pellet had reached the cohesive zone; remaining reduction was completed within the cohesive zone. Coke Lc showed a linear variation with experimental temperature above 11000C; a correlation was established to estimate furnace temperature as a function of EBF depth. The reduction degree of iron ore pellet showed a linear correlation with distance from the stock line of the EBF to the upper part of cohesive zone. But an abrupt increase in reduction rate was observed in the cohesive zone, a result observed in both EBF and experimental studies. The presence of olivine did not have much influence on the reduction degree of iron ore pellets for temperatures below 1100oC in the upper shaft zone of the EBF. However, olivine was found to increase the rate of reduction in the advanced stages of reduction in the cohesive zone for temperatures in excess of 1100oC. This effect was attributed to the formation of increased amount of molten iron oxide within the pellet. The initial melt formation and acceleration of the reduction rate in the cohesive zone of the EBF were also investigated. From the comparison between the reduction degree of excavated olivine pellets in this study and previous studies of EBF, it was found that the excavated pellets were located in the cohesive zone and increase of reduction rate in this zone could be verified by not only the change of gas composition, but also initial melt formation containing FeO phase. The chemical composition of slag phases of excavated pellet samples were located on the line between 2FeO??SiO2 and 2MgO??SiO2 in the FeO-MgO-SiO2 ternary phase diagram. This result is in good agreement with the assumption that the initial slag formation of the olivine pellets had proceeded from the fayalite and after reduction the FeO contents in the slag phase had decreased and eventually precipitated as slag with a higher melting point. From the analysis of carbon contents of the excavated pellets in cohesive zone, it was observed that the carburization of iron pellets began after the complete reduction. This study has established that the reduction rate of iron pellet is the rate controlling step for carburization irrespective of the carburization reaction by the solid carbon.

Thesis (Ph.D. - Chemical and Environmental Engineering)--University of Arizona. / Includes bibliographical references (leaves 158-168).

Thesis (M. Ed.)--University of Adelaide, Dept. of Education, 1993. / Includes bibliographical references (leaves 148-152).

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Chin-Pao Huang, Dept. of Civil and Environmental Engineering. Includes bibliographical references.

Thesis (Ph.D.) Dept. of Organic Chemistry, University of Adelaide, 1983. / Typescript (photocopy).

Thesis (Ph. D., Natural Resources)--University of Idaho, November 15, 2007. / Major professor: James R. Fazio. Includes bibliographical references (leaves 66-76). Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed June 17, 2008). PDF text: 73 p. : ill. ; 3 Mb. UMI publication number: AAT 3290780. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph. D.)--Columbia University, 1923. / Vita.