Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1998. / Includes bibliographical references (p. 88-89). / The hover actuator system is a proof of concept platform. The design models the ability of a flapping foil to assist an undersea vehicle's shallow water sea-keeping performance. Goals of this study are to demonstrate an effective regime of foil motion amplitude, frequency, pitch angle offset, pitch angle amplitude and phase angle for two types of motion. Using the time-averaged thrust coefficient, I find that the lower frequencies provide the highest thrust coefficient of 3.1 at G0=600, hdc= 1.5, and f=0.4Hz for the treading water mode. Significantly lower thrust coefficients are observed for the figure eight mode with maximum of 1.8 occurring at G0=300, hdc=1, and f-0.2Hz. In addition to finding the optimal regime of thrust coefficient, the total thrust is also analyzed to find the regimes of absolute maximum thrust. Again, for the water treading mode the peak thrust was 24Newtons at 00=600, hjc=2.5, and f=0.6Hz; and for the figure eight mode the peak thrust of 7.5Newtons occurs at 00=450, hdc=2.7, and f-0.2Hz. Finally, the rationale of using such an apparatus, arguments, and test results are discussed in conclusion. / by J. Paul Marquardt. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1997. / Includes bibliographical references (leaves 116-121). / by Gregory Robert Thomas. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2001. / Includes bibliographical references (leaf 153). / by Douglas Andrew Read. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1985. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 125-127. / by Woei-Min Lin. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1986. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaf 133. / by Louis King Biegeleisen. / M.S.

Thesis (Nav.E. and S.M. in Ocean Systems Management)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2002. / Includes bibliographical references (leaves 124-132). / The operational envelope of the maritime industry requires high performance marine vessels, which demand increased structural integrity and durability, coupled with significant weight reduction and minimization of cost. The design and fabrication of a "large vessel" by use of composite materials is within the current technology. However, a number of major technical and economic aspects are questionable. This study will examine the structural design for vessels longer than 100 m. It will also identify the major advantages and disadvantages of this composite structure compared with one made of steel, focusing on the technical and economic aspects. Material selection, fabrication methods and design concepts for composite structures, such as elimination of frames, will be explored and comparisons will be developed. The potential to significantly reduce or even eliminate the risk areas will be evaluated. Four different structural designs of a hull from composite materials are examined for a midship section of an existing naval ship (DDG51 type) and they are compared to the one built from steel. In order to select the best option of these structural designs, three variants are analyzed: structural configuration of composites, material option and fabrication process. Additionally, the effect of several critical areas, such as safety factors selection, present and future structural limitations, required fabrication experience, durability, complexity, infrastructure issues, and a cost and market analysis of using fiber reinforced plastic (FRP) in ship design and construction are included in this study. The proposed hull design combined with the optimum materials and fabrication method shows that a large ship is both technically and economically feasible. / by Konstantinos Galanis. / Nav.E.and S.M.in Ocean Systems Management

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2004. / Includes bibliographical references (leaves 126-134). / This thesis presents a parametric and feature-based methodology for the design of solids with local composition control (LCC). A suite of composition design features are conceptualized and implemented. The designer can use them singly or in combination, to specify the composition of complex components. Each material composition design feature relates directly to the geometry of the design, often relying on user interaction to specify critical aspects of the geometry. This approach allows the designer to simultaneously edit geometry and composition by varying parameters until a satisfactory result is attained. The identified LCC features are those based on volume, transition, pattern, and (user-defined) surface features. The material composition functions include functions parametrized with respect to distance or distances to user-defined geometric features; and functions that use Laplace's equation to blend smoothly various boundary conditions including values and gradients of the material composition on the boundaries. The Euclidean digital distance transform and the boundary element method are adapted to the efficient computation of composition functions. Theoretical and experimental complexity, accuracy and convergence analyses are presented. The developed model is a multi-level and graph-based representation, thereby allowing for controls on the model validity and efficiency in model management. The representations underlying the composition design features are analytic in nature and therefore concise. Evaluation for visualization and fabrication is performed only at the resolutions required for these purposes, thereby reducing the computational burden. / by Hongye Liu. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1985. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 213-227. / by John E. Agapakis. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2004. / Includes bibliographical references (p. 78-79). / The purpose of this thesis is to investigate the risk and return characteristics of the shipping business. Shipping profitability and returns are evaluated and an analysis is performed to examine whether the returns are adequate to compensate the amount of risk the investor is bearing. Statistical tools are used to quantify risk and the average returns of the shipping industry are measured and compared with other asset classes. Diversification among different types of ships, and different asset classes is used to maximize the return and minimize the risk of an "efficient fleet". The Capital Asset Pricing Model and the efficient frontier are used to identify the optimal asset allocation. Valuation methods and investment timing techniques are used in order to increase the probability of success and improve the decision making. Finally a real project is evaluated using financial tools. / by Leon S. Patitsas. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1996. / Includes bibliographical references (leaves 155-163). / by Xiaoou Tang. / Ph.D.