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.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1999. / Includes bibliographical references (p. 335-338). / The diffusive nature of shallow water environment limits the fidelity of high performance target sonar systems. The multi-layered ocean waveguide increases the reverberation and the stochastic nature of interface inhomogeneities distorts the target signal. In order to improve the performance in such an environment, an accurate description and a better understanding of background reverberant field are essential. As a theoretical approach, two numerical models have been developed in a consistent framework to simulate multi-static scattered fields produced by rough interfaces and targets in ocean waveguides. The first model describes a scattered field generated by interface roughness in a multi-layered medium. The strong interaction between seismo-acoustic waves and rough interfaces causes a significant amount of surface reverberation. A perturbational approach has been developed for the rough interface scattering. It was combined with 3-D OASES - a seismo-acoustic wave propagation model for a horizontally stratified medium, in order to express multi-layered media efficiently. The model is capable of producing random realizations and spatial statistics of scattered fields in a 3-D space with arbitrary horizontal stratification. Its deterministic scattering formulation for random roughness enables the use of a wide range of roughness types as well as experimental roughness data directly. The second model describes deterministic target scattering. It is based on the plane wave scattering functions of various targets in a free space and the single scattering approximation. As the target models, a rigid sphere, a pressure-release sphere, and a finite cylindrical elastic shell have been used. A scattering theory of finite cylindrical elastic shells has been chosen to investigate the 3-D effects caused by an aspect-dependent object. The plane wave scattering functions are incorporated with 3-D OASES to produce a unified target scattering model within multi-layered media. Compared to the discretization models using full wave theories, the target scattering model developed in this thesis provides a fast way to understand the physics of target scattering in multilayered media without the heavy computational burden of the discretization models. Finally, the rough interface and target scattering models are combined to build a numerical simulator. The numerical simulator is capable of simulating multi-static scattered fields produced by a target in a reverberant background. In order to investigate the feasibility of using a multi-static system, a numerical experiment is performed by using the numerical simulator and the scenario of the GOATS '98 experiment. The numerical simulator provides a realistic forward modeling to aid in understanding the physics of seismo-acoustic scattering in multi-layered media. / by Jaiyong Lee. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1998. / Includes bibliographical references (p. 221-232). / by Christopher Michael Smith. / Ph.D.