Browsing by Subject "Cascade"
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Item Cascade design of single input single output systems using H∞ and quantitative feedback theory methodologies(Texas A&M University, 2005-02-17) Lal, MayankThis thesis considers the design of cascaded SISO control systems using the H∞ and QFT methodologies. In the first part of the thesis the actual advantages offered by Single Input Single Output (SISO) cascade loop structures are studied. In Quantitative Feedback Theory(QFT) it is emphasized that the use of cascaded loops is primarily for the reduction of bandwidth of the controllers. This in turn helps in considerable reduction of the adverse effects of high frequency noise. The question that arises then is whether or not there are any substantial benefits to be gained by cascade loop design in the low frequencies. It is shown using QFT methodology that there aren?t any advantages gained in the low frequencies with the use of cascaded design. In effect it is concluded that if the design is properly executed a single loop controller closed from the output to the input will be sufficient to meet the typical performance specifications. This is shown using an example where the mold level of a continuous casting process is to be controlled. The plant being used has considerable uncertainty so that features of robust control can be highlighted. In the second part the Robust Outer Loop bounds were generated analytically and examined for certain properties. It was compared to the bounds generated by already existing algorithms. In the third part the inner outer QFT design was modified with the inner loop being designed using H∞ with the concept of sensitivity shaping. This design was very similar to the pure QFT design with the added advantage of having some automation. In the fourth part the H∞ methodology was used to design a two loop control structure. The idea was to compare this design to the QFT design. It was seen that H∞ generated redundant controllers and pre filters.Item Kinematic and Mechanical Reconstruction of Walker Ridge Structures, Deepwater Gulf of Mexico(2011-02-22) Majekodunmi, Oluwatosin EniolaRecent high-resolution seismic imaging has allowed detailed reconstruction of the relationship between fold development and crestal faulting of the Chinook and Cascade folds in the deepwater Gulf of Mexico. Using 3-D seismic and biostratigraphic data, we have found that (1) short wavelength (~2300m), small amplitude folds (~540m) within the upper Cretaceous and upper Jurassic stratigraphic sequences took place no later than the late Jurassic, (2) large wavelength and amplitude fold growth, starting in the early Cretaceous, was produced by salt withdrawal, and (3) periods of increased sedimentation, fold growth, and fault slip occurred during the middle Miocene and late Miocene. Although the dominant stage of long wavelength, large amplitude fold growth started around early Cretaceous, the development of the Cascade and Chinook structures was continuous, punctuated by episodes of accelerated growth during the middle Miocene at rates of 337 and 235 m/Ma in the Cascade and 203 and 230 m/Ma in the Chinook. A later event of accelerated growth occurred during the late Miocene at rates of 1038 m/Ma in the Cascade and 1189 m/Ma in the Chinook. Accompanying fold growth was sedimentation, which was highest at 1949 m/Ma in the Cascade and 2585 m/Ma in the Chinook. Although limb tilt rates varied through fold growth, the highest rates also occurred during the middle Miocene at 0.330 and 0.196 degree/Ma for the Cascade and Chinook, respectively with the development of crestal faults at maximum slip rates of 88 and 90 m/Ma.