Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2004. / Includes bibliographical references (p. 251-258). / Despite its coarse approximation of physics, the phase-averaged wave spectrum model has been the only type of tool available for ocean wave prediction in the past 60 years. With the rapid advances in sensing technology, phase-resolved nonlinear wave modeling, and high performance computing capability in recent years, the time has come to start developing a new generation tool for ocean wave prediction using direct phase-resolved simulations. The key issues in developing such a tool are: (i) proper specification of initial/boundary conditions of the nonlinear ocean wave-field; (ii) development of efficient algorithm for simulation of large-scale wave-field evolution on high performance computing platforms; (iii) modeling of nonlinear physics in ocean wave evolution such as wave-wave, wave-current, wave-bottom and wave-wind interactions. The objective of this thesis is to address (i), (ii) and part of (iii). For (i), a multi-level iterative wave reconstruction tool is developed to deter- ministically reconstruct a nonlinear ocean wave-field based on single or multiple wave probe records, using both analytic low-order Stokes solutions and High-Order-Spectral (HOS) nonlinear wave model. / (cont.) With the reconstructed wave-field as the initial conditions, the ocean wave-field can then be simulated and forecasted into the future deterministically with the physics-based phase-resolved wave model. A theoretical framework is developed to provide the validity of the reconstructed wave-field and the predictability of future evolution of the reconstructed wave-field for given wave conditions. The effects of moving probe, ambient current and finite water depth on the predictable region are studied respectively. To demonstrate its efficacy and useful- ness, the wave reconstruction tool is applied to reconstruct the full kinematics of steep two- and three-dimensional irregular waves using both wave-basin measurements and synthetic data. Excellent agreements between the reconstructed nonlinear wave-field and the original specified wave data are obtained. In particular, it is shown that the inclusion of high-order effects in wave reconstruction is of significance, especially for the prediction of the wave kinematics such as velocity and acceleration. For (ii), a highly scalable HOS wave model is developed and applied to study both two- and three-dimensional ocean wave-field evolution for a realistic space and time scale. / (cont.) Effective filtering tools are developed to model the wave breaking process in wave evolution. For (iii), the HOS wave model is enhanced to account for not only nonlinear wave-wave interactions, but also nonlinear wave interaction with variable ambient current. With this tool, the effects of variable ambient current on nonlinear wave-field evolution are investigated. As a final illustration, this tool is applied in practical ship motion control. Based on the deterministically forecasted wave-field provided by this tool, an optimal path is obtained to reduce the RMS heave motion of ship in point-to-point transit. / by Guangyu Wu. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1983. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 99-102. / by Sea Heon Kim. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2004. / Includes bibliographical references (leaves 142-146). / Countries are looking beyond their borders for options to satiate a forecasted increase in natural gas consumption. A strong option for importing natural gas is by way of a liquefied natural gas (LNG) supply chain where natural gas is liquefied, transported in special tankers, and regasified at the destination. Research was conducted to determine a method of evaluating the feasibility of such a project. A computer-based simulation model was created to calculate financial metrics for potential LNG projects based on unique inputs such as annual production, distance, and natural gas market and commodity price. Potentially feasible projects are based on the resulting metrics as well as interpretations of risk, and a source's ability to meet a consuming market's demand requirements. Financially, the most attractive projects were the short haul routes to countries with high market prices. However, due to risk and supply inadequacy, it was determined that markets with the most growth to satisfy were best supplied by countries with the most adequate resources. / by Richard Perry Connell. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1992. / Includes bibliographical references. / by Donald Blandford Peters. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1991. / Includes bibliographical references (leaves 139-143). / by Woojae Seong. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1995. / Includes bibliographical references (leaves 85-89). / by Regina A. Middaugh. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994. / Includes bibliographical references (p. 158-166). / by Kenneth D. Rolt. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2001. / Includes bibliographical references (leaves 197-204). / For the weight efficient and crashworthy design of the structural body of a transportation system, a thorough understanding of crushing behavior of thin-walled structural members such as spot-welded sheet metal beams or extruded aluminum beams must be gained. In the present thesis, the complex crushing process of three-dimensional thin-walled structures subject to combined loading is solved analytically and numerically. Also, several new design concepts of strengthening "S" shaped frame with regard to weight efficiency and energy absorption are proposed. The mechanics of biaxial bending collapse and the collapse under combined bending and compression of thin-walled prismatic member are formulated and initial and subsequent shrinking interaction curves between the loading components are constructed. All the analytical derivations show close correlations with the results of the accompanying finite element analysis. Based on these two complex crushing mechanisms, the analytical derivation of the crushing resistance of three-dimensional "S" shaped frame is presented. Extensive study on the strengthening of the three-dimensional "S" shaped frame is performed with two types of internal reinforcing member, diagonally positioned sheet metal stiffener and ultralight metallic foam-filler. The optimization process involving varying the cross-sectional shape and the type of reinforcing member for both aluminum-extruded member and spot-welded hat-type cross-section member is developed. / (cont.) Using the analytical closed form expression of the crushing force of "S" shaped frame, the optimization process was performed based on Sequential Quadratic Programming. As a more realistic application, a front side rail and subframe structure of a mid size passenger car is analyzed. The combinational optimization process of "Design of Experiment" and "Response Surface Method" is carried out with the objective of weight minimization while maintaining the same or higher level of crash energy absorption. Both methods of internal reinforcement show high increase in the energy absorption and weight efficiency. The gain in terms of the specific energy absorption varies from 37% to 267% depending on the method. The proposed theoretical understanding and the design methodologies could be used as crash oriented early-stage component design tools. / by Heung-Soo Kim. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994. / Includes bibliographical references (leaves ). / by Matthew P. Tedesco. / M.S.

Thesis (Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2000. / Includes bibliographical references (leaves 104-107). / by Paul Richard Wynn. / Nav.E.