Thesis (Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998. / Includes bibliographical references (p. 49). / The vibration suppression effectiveness of a flexible in-line marine cable vibration absorber is studied. The transfer matrix method is used to build various numerical models of vibration absorbers in marine cable systems. The models determine cable system natural frequencies, mode shapes and modal damping ratios. The introduction of absorber damping is shown to result in complex roots to the modal characteristic equations. A computer complex root solver is used to solve for the complex roots of the characteristic equations, resulting in complex system natural frequencies. The significance of complex natural frequencies is explained. Complex natural frequencies are used to calculate modal damping ratios. The models demonstrate that absorber effectiveness is heavily dependent on absorber location, absorber mass and absorber length. Parametric variation is used to achieve maximum effectiveness of the flexible in-line absorber. Even under optimum conditions, it is shown that the absorber provides insufficient damping to reduce vortexinduced vibrations in water. The same transfer matrix method is used to evaluate the effectiveness of a massspring- dashpot type absorber in a marine cable system. This type of absorber is shown to produce adequate damping to reduce vortex-induced vibrations in water. The transfer matrix method used in this thesis is validated by analyzing the same system using an approach by Den Hartog [1]. The transfer matrix approach combined with complex root solving capability is shown to provide an effective analysis method for marine cable systems. / by Christopher R. Levesque. / M.S. / Nav.E.

Oil spills are a frequent occurrence in the Gulf of Mexico (GOM). They occur by two principle processes: natural oil seepage and accidental spills during petroleum extraction, transportation, and consumption. Marine oil spill can be highly dangerous because wind, waves, and currents can scatter an oil spill over a wide area in a few hours. Accurate detection and predicting the fate of oil not only from large spills, but also chronic small-scale emissions lead to a better investigation of the effect of oil on the environment. Remote sensing plays an important role in oil spill response and monitoring by providing the oil slick location and its spatial and temporal distribution. The aim of this dissertation was to use Synthetic Aperture Radar (SAR) images in the GoM as a means to, map the location of the anthropogenic oil slicks reported by National Response Center (NRCen) and quantify their volume, identify chronic oil spill locations, analyze oil slick extent and drift by wind and surface currents, study the fate of Deepwater Horizon (DWH) oil spill. This dissertation consists of studies that are compiled into three manuscripts that are published, accepted for publication or ready for submission. One of the objectives in this research was to examine the feasibility of SAR images in oil slick detection. We used SAR images to obtain more precise estimates of the magnitude of the hydrocarbon discharges reported by NRCen in the GoM. These reports depend largely on unverified reporting from responsible parties and third parties, have not been validated by an independent assessment in terms of location and magnitude, and associated with three categories of source: 1) pipelines, platforms, or other energy industry sources, 2) the former location of the Taylor offshore platform, and 3) undetermined sources. A total of 67 reports were visible in 66 archived SAR images from 2004 to 2012 describing transient events. Of those, oil slicks observed at the Taylor site were generally much larger than those corresponding to other NRCen reports, and indicated a chronic source at this location. These long wind-driven layers of floating oil released from the Taylor site were verified by field sampling, aerial photography, Landsat 7 Enhanced Thematic Mapper Plus (ETM+) 30-m resolution data, and Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua medium resolution (250-500 m) data. A Texture Classifying Neural Network Algorithm (TCNNA) delineated oil slicks area from SAR images. Comparison of SAR-extracted and NRCen-reported oil slicks areas showed a consistent under reporting by NRCen. Our second objective was to estimate the surface residence-time of the oil slicks and to determine the importance of wind and surface currents on the trajectory and fate of the released oil. Oil slicks released from natural hydrocarbon seeps located in Green Canyon 600 (GC600) lease block in the GoM were analyzed in 41 SAR images. A relatively simple surface oil drift model deriving with wind and surface currents was used to obtain the closest resemblance between the simulated oil pathways and the length and shape of the oil slicks observed in SAR images. The average surface residence-time predicted from the hindcast modeling was 6.4 hr (± 5.7 hr). Respectively, the effect of winds and surface currents on disappearance and stretching of the oil slicks from sea surface were indicated. Results from the numerical experimentation were supported by in situ observations conducted by a wind-powered autonomous surface vehicle (SailDrone). Finally, our third objective was to discuss the fate of remaining oil after the DWH oil spill. The hypothesis of what happened to the surface discharge of DWH oil was tested by surface oil advection model, weathering, and fate data. The inputs of surface oil advection model derived from: 1) The volume distribution of floating oil during the DWH discharge quantified by 166 SAR images, 2) Modeled wind time series from the North American Mesoscale Forecast System (NAM), 3) Ocean currents from the HYbrid Coordinate Ocean Model (HYCOM). Evaporation of volatiles from surface oil was simulated by Oil Spill Contingency And Response (OSCAR) model. Daily magnitude and spatial distribution of aerial dispersant application and burning operations were obtained from publicly available databases. At each time step these weathering and fate data were subtracted from the modeled distribution of oil volume on the water surface. Results were compared to SAR images of DHW oil spill in order to verify the amount of oil which was 1) suspended below the surface or buried through sedimentation, 2) washed ashore, and 4) resurfaced through time. / A Dissertation submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the Doctor of Philosophy. / Spring Semester 2017. / February 1, 2017. / Includes bibliographical references. / Ian R. MacDonald, Professor Directing Dissertation; Tarek Abichou, University Representative; Mark Bourassa, Committee Member; William Dewar, Committee Member; Dmitry Dukhovskoy, Committee Member.

Thesis (Ocean E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering, 1984. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Kenneth A. Lively. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, and Dept. of Nuclear Engineering, 1987. / Bibliography: leaves 104-107. / by James H. Wicks, Jr. / M.S.

Thesis (S.M. in Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2002. / Includes bibliographical references (leaves 77-78). / The resurgence of interest in the use of nuclear technology for electrical power production has resulted in a desire to improve the existing licensing structure. Improving the licensing structure will result in reduced design time and cost for new reactor plants. An improved regulatory process is also necessary in order to license advanced reactors that are not light water technology. Risk based reactor licensing, which uses the Probabilistic Risk Assessment (PRA) to justify most licensing questions, is a proposed replacement for the current methods. This work further develops the risk-based regulatory process by analyzing a portion of a new reactor concept. A reactor similar to the Pebble Bed Modular Reactor (PBMR) is the design chosen for the analyses. The designers of the PBMR assert that the reactor's inherently safe design justifies the use of a non-standard containment system. This assertion can be treated as a design question to be justified using the risk-based approach. The effect of the changing the containment system is incorporated into the PRA for the PBMR. The contributions to the event and fault trees of the PBMR are determined for two casualties that affect the plants decay heat removal system. The initiating event for both of these casualties is assumed to be a beyond design basis earthquake. The first casualty is steam blanketing of the reactor vessel due to a rupture in the Reactor Cavity Cooling System (RCCS). This casualty is shown to have little effect on the safety of the plant. The second casualty was failure of the RCCS due to operator inaction. If this casualty were to occur the reactor vessel has the possibility of failing catastrophically. The failure of the reactor vessel could result in damage to the fuel and release of radionuclides. The probability of this casualty resulting in a significant release of radionuclides is 7.5-10-11 / year. For the two casualties evaluated in this work, the use of a non-standard containment is justified. / by Jon E. Withee. / S.M. / S.M.in Naval Architecture and Marine Engineering

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering, 1994. / Includes bibliographical references (leaves 71-75). / by Evan Conway Sherbrooke. / M.S.

Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering, 1994. / Includes bibliographical references (leaves 80-82). / by Melissa C. Smoot. / M.S. / Nav.E.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1996, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering, 1996. / Includes bibliographical references (p. 77-78). / by Jun Yan. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (leaf 84). / Autonomous Underwater Vehicles (AUV's) are becoming of increasing use in shallow waters for oceanographic data collection, coastal mapping, and military operations such as mine surveillance along enemy coastlines. Currently the control of AUV's in shallow water is very limited, largely due to a lack of knowledge of vessel forces in shallow water, especially in the presence of surface wave effects. The limitations of current control systems do not afford enough confidence to operate the vehicles in very close proximity to shore or in large waves because the control in the horizontal plane is not adequately reliable enough to prevent bottoming and free surface broaching. Current control system parameters are altered through trial and error to enable reasonable vehicle behavior in shallow water but the control of the vehicle is limited because a thorough understanding of wave forces on these vehicles is non existent. The development of a good analytical tool which adequately models wave forces and moments on an AUV in shallow water waves will enable the development of control systems which will be better able to maneuver the vehicle in shallower water and larger waves than the conditions in which AUV's are currently used. / (cont.) The purpose of this thesis is to further develop, verify, and apply a Strip Theory based analytical tool, which has been developed by Prof. Jerry Milgram. The developed code models dynamic wave forces on a small submarine in shallow submergence and finite depth water through the use of a Strip Theory summation of cross section forces calculated through Green's theorem in a two dimensional panel method code. For this thesis a study of three dimensional flow effects on the control fins is conducted through the use of WAMIT, a three-dimensional panel method code for marine structures. The code is tested for data convergence to determine the sizing of both the Greens theorem solution domain and the panel sizing for the solution. To validate the accuracy and reliability of the Strip Theory Code in question, its results are compared to WAMIT output for identical test conditions. Also, existing experimental data for the REMUS AUV is used as a comparison and validation for the code. The resulting code correctly models sway, heave, pitch, and yaw forces and moments with reasonable accuracy and it can be used in future work to develop more reliable control systems and operating limitations for AUV's. / by Jan A. Rybka. / S.M.

Thesis (Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2001. / "June 2001." / Includes bibliographical references. / by Mark Robert Galvin. / Nav.E. / S.M.