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Thesis (Ph. D. in Engineering)--University of California, Berkeley, 2005. / Includes bibliographical references (p. 64-66). Also available online via the University of California web site (http://repositories.cdlib.org/escholarship/).

Petroleum exploration and production in recent years have moved into increasingly deeper water off the continental shelf. Some of these facilities are anchored in water depths in excess of 1000 meters. Exploration and production in deep water present new technological challenges where traditional fixed platforms have given way to floating structures. Today suction caissons are the most commonly used anchorage system for permanent offshore oil production facility. The objective of this study is to numerically predict the ultimate capacity of suction caissons in normally consolidated and lightly overconsolidated clays. Representative soil profile from the Gulf of Mexico and the North Sea are taken and analyzed for suction caissons with length over diameter ratios of 2, 4, 6 & 8. Normalized failure load interaction diagrams are generated for each of the cases. The location of optimum attachment point is also reported for each of the cases. General purpose finite element computer program ABAQUS is used for the numerical prediction. The finite element study is carried out with three-dimensional models using hybrid elements. A simplified elastic perfectly plastic model with von-Mises yield criterion is used for the study. The saturated clay is treated as an incompressible material. Results of the study compares well with existing simplified method for estimating load capacity of suction caisson anchors.

In a CR network, the maximum SUs throughput is desired generally. In this thesis, We investigate and formulate the problem of the secondary users¡¦ throughput maximization in cognitive radio systems under channel capacity constrain. By using KKT theorem, an objec- tive function is developed to obtain an optimal solution for the SU throughput maximization problem. An numerical example is also presented for illustration. The most important results revealed in the example show that the maximum SU throughput is achieved by cooperating an optimal number of SU pairs instead of cooperating all the SU pairs.

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Petroleum exploration and production in recent years have moved into increasingly deeper water off the continental shelf. Some of these facilities are anchored in water depths in excess of 1000 meters. Exploration and production in deep water present new technological challenges where traditional fixed platforms have given way to floating structures. Today suction caissons are the most commonly used anchorage system for permanent offshore oil production facility. The objective of this study is to numerically predict the ultimate capacity of suction caissons in normally consolidated and lightly overconsolidated clays. Representative soil profile from the Gulf of Mexico and the North Sea are taken and analyzed for suction caissons with length over diameter ratios of 2, 4, 6 & 8. Normalized failure load interaction diagrams are generated for each of the cases. The location of optimum attachment point is also reported for each of the cases. General purpose finite element computer program ABAQUS is used for the numerical prediction. The finite element study is carried out with three-dimensional models using hybrid elements. A simplified elastic perfectly plastic model with von-Mises yield criterion is used for the study. The saturated clay is treated as an incompressible material. Results of the study compares well with existing simplified method for estimating load capacity of suction caisson anchors.

Oyster farming is an important mariculture along the western coast of Taiwan. There is always impacts on the oyster farming. The information of frequency, size and timing of tyhoon every year is strongly connected to the decisions of starting and harvesting of oyster culture. Climate change or variation seem to examine the future management of an oyster farm. This study aims to understand the adaptive strategies of oyster farmers in Tainan to possible climate change or variability. To analyze the mechanism of adaptive capacity and decision-making through a qualitative approach, specially , with focus groups, in-depth interviews, and semi-structured questionnaires. The results revealed abundant adaptation existing in the oyster farmers in Tainan, such as selecting small-size or median-size oyster as a way to cope with typhoon. However information exchange is rare among focus groups and more training and out reach courses are suggested.

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