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‣ Dynamics of elastic taut inclined cables

Grinfogel, Laurent
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 67 leaves; 1738118 bytes; 1737925 bytes; application/pdf; application/pdf
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by Laurent Grinfogel.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1984.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Prediction of ductile crack formation in uncracked bodies

Bao, Yingbin, 1972-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 252 p.; 10776176 bytes; 10775975 bytes; application/pdf; application/pdf
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One of the important challenges facing the scientific and engineering community is the development of a reliable computational tool for predicting failure of structures under extreme and/or accidental loads. Considered in the present thesis is the process of formation of ductile cracks, which may be responsible for a catastrophic structural failure. Experimental, numerical and analytical studies are carried out on the prediction of ductile crack formation in uncracked bodies on an example of 2024-T351 aluminum alloy. A methodology for ductile crack formation suitable in industrial applications is developed through the introduction of different weighting functions for different stress triaxiality ranges where different ductile crack formation mechanisms occur ("shear fracture" in negative stress triaxialities, void nucleation, growth, and linkage in high stress triaxialities, a transition mode in intermediate stress triaxialities). A cut off value at the stress triaxiality of -1/3 is discovered. Effects of stress and strain ratios, specimen size and anisotropy are also quantified. It is found that the stress triaxiality and the equivalent strain are the two most important parameters governing ductile crack formation while other parameters are probably of secondary importance. A modification to the criterion is introduced to predict crack formation in a single reversal of straining. A case study of a solid aluminum 2024-T351 beam with a smooth round notch under 3-point bending is conducted.; (cont.) Other cases of component validations on different materials...

‣ Application of system identification to ship maneuvering

Hwang, Wei-yuan
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 316 leaves; 12813178 bytes; 12812931 bytes; application/pdf; application/pdf
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by Wei-Yuan Hwang.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography: leaves 289-293.

‣ The estimation of natural frequencies and damping ratios of offshore structures

Campbell, Robert Bradlee
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 219 p.; 11169433 bytes; 11169190 bytes; application/pdf; application/pdf
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by Robert Bradlee Campbell.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Analytical techniques for determining temperatures, thermal strains, and residual stresses

Papazoglou, V. J. (Vassilios John)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 292 leaves; 14438636 bytes; 14438390 bytes; application/pdf; application/pdf
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by Vassilios John Papazoglou.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1981.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ On the diffraction of free surface waves by a slender ship

Sclavounos, Paul D.
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 155 leaves; 7471280 bytes; 7471035 bytes; application/pdf; application/pdf
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by Paul Sclavounos.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1981.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography: leaves 124-126.

‣ The guyed tower offshore platform : preliminary design considerations

Johnson, Kevin LeRoy
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 219 leaves; 10398799 bytes; 10398558 bytes; application/pdf; application/pdf
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by Kevin LeRoy Johnson.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1982.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Piston slap noise in diesel engines

Slack, James W
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 134 leaves; 5912369 bytes; 5912132 bytes; application/pdf; application/pdf
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by James W. Slack.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1982.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Dynamics of unbalanced drill collars in a slanted hole

Rey, Olivier F
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: [1], 119 leaves; 4236242 bytes; 4236003 bytes; application/pdf; application/pdf
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by Olivier F. Rey.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1983.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Bibliography: leaf 72.

‣ Theoretical and experimental procedures for the prediction of the dynamic behavior of marine risers

Patrikalakis, N. M. (Nicholas M.)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 272 leaves; 14143355 bytes; 14143114 bytes; application/pdf; application/pdf
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by Nicholas Marinos Patrikalakis.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1983.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Bibliography: leaves 259-264.

‣ Efficient container fleet expansion

Maillis, Michael Ilias
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 112 leaves; 4993941 bytes; 4993701 bytes; application/pdf; application/pdf
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by Michael Ilias Maillis.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1983.; THESIS AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Optimal container loading

Aslidis, Anastasios Haralampos
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 126 leaves; 5730471 bytes; 5730229 bytes; application/pdf; application/pdf
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by Anastasios Haralampos Aslidis.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1984.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography: leaf 74.

‣ Dynamic analysis of single span cables

Bliek, Antoine
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 295 leaves; 13676723 bytes; 13676475 bytes; application/pdf; application/pdf
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by Antoine Bliek.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1984.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography: leaves 269-295.

‣ Analysis of an axisymmetric pneumatic buoy by reciprocity relations and a ring-source method

Fernandes, Antonio Carlos
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 182 leaves; 8176082 bytes; 8175842 bytes; application/pdf; application/pdf
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by Antonio Carlos Fernandes.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1984.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography: leaves 180-183.

‣ The stochastic behavior of spot freight rates and the risk premium in bulk shipping

Adland, Roar Os, 1972-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 146 p.; 5748945 bytes; 5748753 bytes; application/pdf; application/pdf
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The value of virtually any contract or asset in bulk shipping depends primarily on the stochastic dynamics of the forward freight rate curve. In the absence of a liquid and transparent market for forward freight agreements, the dynamics of the forward freight rate curve must be derived from the dynamics of the spot freight rate and the risk premium in the freight market. This thesis is an attempt to improve our understanding of the stochastic dynamics of freight rates and the nature and sources of risk in the freight markets. Two new spot freight rate models are proposed and estimated, applying nonparametric estimation in an effort to avoid misspecification. It is found that while a one-factor Markovian model can capture the mean reversion and level effect in the spot freight rate very well, an extension to a multi-factor non-Markovian model is required in order to account for the observed lag effects in the conditional mean and variance. New theory governing the risk premium in the freight markets is proposed, which suggests that the theoretical risk premium should be time varying and, in general, depend on the state of the freight market and the duration of the period charter in a systematic fashion. Empirical tests suggest that the implied risk premium changes over time...

‣ A strategy for the use of light emitting diodes by autonomous underwater vehicles; Strategy for the use of LEDs by AUVs

Curran, Joseph R. (Joseph Robinson)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 169 leaves; 9101133 bytes; 9108282 bytes; application/pdf; application/pdf
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Light Emitting Diode (LED) technology has advanced dramatically in a few short years. An expensive and difficult to manufacture LED array containing nearly 100 individual LEDs and measuring at least 5 cm² can now be replaced by a single 5 Watt LED smaller than a quarter. As the light output for a given package size continues to increase, doubling every two years, it is possible to consider using these new LEDs to improve existing lighting systems and to explore non-traditional methods of underwater photographic illumination. So, can these high-output LEDs be used for underwater illumination, under what circumstances are they a good choice, and what is the optimal way to deploy them for a given set of conditions? In this thesis I attempt to answer these questions. In this thesis, I tested these 5W LEDs in a number of conditions and orientations in order to simulate the lighting conditions experienced by autonomous underwater vehicles (AUVs) illuminating and imaging targets on the ocean floor. These LEDs were characterized and compared to existing lighting systems and methods. Their suitability for use both as vehicle-carried illumination and off-the-vehicle lighting packages was examined.; (cont.) Finally, conclusions were drawn as to the effectiveness of the 5W LEDs for underwater illumination and a guideline for LED illumination is presented to help AUV researchers determine the optimal lighting package for use on their missions.; by Joseph R. Curran.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ Motion control of high-speed hydrofoil vessels using state-space methods

Chatzakis, Iason
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 110 p.; 4857542 bytes; 4862096 bytes; application/pdf; application/pdf
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Hydrofoil ships cruise at large speeds and are often expected to operate in rough weather conditions. The motion of these ships due to their encounter with ambient waves can become uncomfortable or even dangerous without the use of some form of motion control. The objective of this thesis is to study the active motion control of high-speed hydrofoil vessels. This work is composed of two parts, reflecting the two disciplines applied: hydrodynamics and optimal control theory. In the first part, a two-dimensional computer code is developed for the calculation of forces and the integration of the equations of motion for fully submerged lifting bodies operating near a free surface. A Rankine source boundary element (panel) method is used assuming potential flow around the body. As a result, the motions of a hydrofoil vessel operating at high speed in ambient waves can be estimated in the time domain. In the second part, the application of optimal control theory to motion control of hydrofoil ships is investigated. The code developed in the first part of this work is used as a simulation tool for the assessment of control laws designed using state-space linear-quadratic methods.; (cont.) It is found that a linear-quadratic optimal controller can attenuate the motion response of the vessel advancing in monochromatic or ocean waves...

‣ Experimental investigation of small-scale breaking waves : flow visualization across the air-water interface

McDonald, Angus Kai
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 140 p.; 8533766 bytes; 8539663 bytes; application/pdf; application/pdf
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The dynamics of breaking waves significantly affect air-sea fluxes of heat, momentum, mass and energy across the ocean interface. Breaking waves also contribute considerable loading to offshore and coastal structures, and furthermore, the quasi-steady bow wave on a ship increases drag and ease of detection by the bubbly wake. However, the complexity of the phenomenon has severely limited our ability to describe it and predict its occurrence. Research has typically involved field observations, controlled laboratory studies, and numerical simulations. A recent simulation presented new information about local energy dissipation and the coupled air-water effects of small breaking waves. In light of these findings, the objective of this thesis is to experimentally study small-scale breaking waves and examine the combined air-water flow fields using advanced visualization techniques. This research was performed in a narrow wavetank which was 2.5m long. Waves were generated with a hinged paddle and breaking occurred as the train propagated up a 15 degree slope to a level plateau. Waves were studied using surface piercing wave probes, high speed video, and Particle Image Velocimetry (PIV).; (cont.) Surface tension was found to have a significant effect on the breaking dynamics at this scale. After a thorough exploration of its effect on surface tension...

‣ Design of a mobile coastal communications buoy

Hendry-Brogan, Meghan
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 80 leaves; 5414175 bytes; 5417466 bytes; application/pdf; application/pdf
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In response to a growing interest in networked communications at sea as well as the needs of our vital commercial fishing industry, the Northeast Consortium funded a novel research initiative to establish wireless acoustic and radio communications at sea. The platform used for this type of telemetry instrumentation was to be a buoy which could not only withstand the often harsh conditions off the northeastern coast of America (specifically, Cape Ann), but do so while exhibiting an exceptionally small response in heave and roll. A spar type buoy was designed and built at the MIT Sea Grant facility. Spars are a special type of buoy shape whose hydrostatic and hydrodynamic interactions with the sea are decoupled enough so that extreme sea conditions do not induce extreme buoy motions. Most oceanographic buoys are of the discus type, and move as the surface of the ocean does. This type of wave-following buoy would not sufficiently facilitate the requirements of the high-bandwidth wireless networking hardware, and therefore would not serve the current purpose.; (cont.) The NEC buoy displaces approximately 140 kg of sea water and is roughly 11 feet long when fully assembled, not including its 5 foot antenna mast. The buoy employs a PC104 stack to control an 802.1 lb wireless card and antenna...

‣ Dynamic sonar perception

Rikoski, Richard J
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 192 leaves; 9517498 bytes; 9529103 bytes; application/pdf; application/pdf
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Reliable sonar perception is a prerequisite of marine robot feature-based navigation. The robot must be able to track, model, map, and recognize aspects of the underwater landscape without a priori knowledge. This thesis explores the tracking and mapping problems from the standpoint of observability. The first part of the thesis addresses observability in mapping and navigation. Features are often only partially observable from a single vantage point; consequently, they must be mapped from multiple vantage points. Measurement/feature correspondences may only be observable after a lag, and feature updates must occur after a delay. A framework is developed to incorporate temporally separated measurements such that the relevant quantities are observable. The second part of the thesis addresses observability in tracking. Although there may be insufficient information from a single measurement to estimate the state of a target, there may be enough information to observe correspondences. The minimum information necessary for a dynamic observer to track locally curved targets is derived, and the computational complexity is determined as a function of sonar design, robot dynamics, and sonar configuration. Experimental results demonstrating concurrent mapping and localization (CML) using this approach to early sonar perception are presented...