Dissertations / Theses: 'Marine and Ocean Engineering'

1

Keenan, David P. "Marine propellers in unsteady flow." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14348.

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2

Jastram, Michael Oliver. "Inspection and feature extraction of marine propellers." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/42632.

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3

Hadjistassou, Constantinos Kyprou. "International maritime organization : rethinking marine environmental policy." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33579.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2005.
Includes bibliographical references (leaves 67-70).
As environmentalism has swept into political prominence, influencing the environmental policy of developed nations, the IMO- the UN dedicated legislator of the shipping industry- has been increasingly faced with challenges to its decision making process as well as to the effective fulfillment of its role. The current treatment of environmental matters, especially when it comes to negotiations for enacting universally accepted and implemented regulations seems to be in need for reconsideration. This is mainly the case because, the systematic adoption of unilateral/regional measures, at best, can undermine the status of the IMO and, at worst, may prove disruptive to international shipping. The purpose of this thesis is to put concerns over the role of the IMO in international environmental regulations negotiations into a specific context and attempt to view the organization's treatment of the issues it is faced with from a perspective which will reveal the strengths and the shortcomings of the IMO, so that credible remedies could be suggested. In order to achieve this goal, three case studies were used namely the Member States, the Interest Group, and the Industry case study.
(cont.) These cases- selected to identify areas of improvement for the 1MO- have demonstrated that the agency's working procedures merit reassessment if the agency is to remain the industry's legislator. A close examination of the conclusions extracted from the three case studies reveals that the MO is faced with the challenge of leveraging multiple types of initiatives which can emanate from powerful maritime nations, coalition/regional groups, interest groups, stakeholders, and the public.Consequently, if it is to serve its purpose effectively and efficiently, the IMO ought to develop the institutional mechanisms that will encourage policy innovations in the realm of international environmental negotiations whilst strengthening the agency's status as the industry's legislator. Similarly, in view of its evolving role, the agency has to act proactively so as to strike a balance between environmentally sound and sustainable shipping. The closing chapter of the thesis indicates that judging the present and the future of the [MO should be done in the light of excessive pessimism, since some initiatives already underway may improve the current situation, but there is still a lot of room for improvement.
by Constantinos Kyprou Hadjistassou.
S.M.

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4

Calder, Jon P. (Jon Patrick) 1955. "Application of freight identification technologies to marine transportation." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9552.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1999.
Includes bibliographical references (p. 113-115).
This study was carried out to investigate the use of freight identification technology for marine container tracking. This research was also intended to evaluate the different forms of the technology and enlighten ocean carriers on the strengths and weaknesses of each technology. The various currently available products and the technologies they represent are identified along with their technical characteristics. Three metrics are identified to assist in evaluating the technologies for this application. These are: Level of Service, Cost, and Institutional or Legal factors. The technologies are evaluated in relationship to these metrics and several implementation strategies are suggested. Included are descriptions of some of the technical background and features of the technologies.
by Jon P. Calder.
S.M.

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5

Wu, Wusheng. "Interaction between two marine risers." Thesis, University of Glasgow, 2003. http://theses.gla.ac.uk/4009/.

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This thesis takes top tensioned vertical riser interaction as its main study object. It has its focus on the understanding of the mechanism about potential instability of the risers caused by the interaction and the prediction of potential collision. Started from two-dimensional cylinder interaction cases, and later extended into the three-dimensional riser scenarios, the problem is investigated comprehensively. The study covers fluid force prediction, stability analysis, continuation investigation and dynamics simulation. The study disclosed the mechanism of the potential collision when the flow velocity reaches a certain critical value, and provides a robust tool to predict the threshold for the riser collision. Additionally, the investigation shows the difference between marine riser interaction and the similar interaction occurs in other engineering disciplines, such as power transmission lines, heat exchangers etc. Also provided in this thesis are valuable information regarding the riser dynamics should collision occur. The research will be beneficial to the marine riser designers and operators.

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Duerr, Phillip S. "Investigation of marine waterjet inlets during turning maneuvers." Thesis, Florida Atlantic University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10095898.

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Numerical simulations of waterjet inlets have been conducted in order to understand inlet performance during ship turning maneuvers. During turning maneuvers waterjet systems may experience low efficiency, cavitation, vibration, and noise. This study found that during turns less energy arrived at the waterjet pump relative to operating straight ahead, and that the flow field at the entrance of the waterjet pump exhibited a region of both low pressure and low axial velocity. The primary reason for the change in pump inflow uniformity is due to a streamwise vortex. In oblique inflow the hull boundary layer separates when entering the inlet and wraps up forming the streamwise vortex. These changes in pump inflow during turning maneuvers will result in increased unsteady loading of the pump rotor and early onset of pump rotor cavitation.

Simulations covered drift angles from 0° to 30°, pump velocities relative to free stream speed of 0.6 to 1.0 for inlet geometries with ramp angles of 25° and 30° with inlet-hull fairing radii relative to pump diameter of 0.1 to 0.2. The following observations were made: 1) the onset of the streamwise vortex occurred between drift angles of 5° and 10°; 2) increasing drift angle increased the strength of the streamwise vortex and lowered the energy of the flow entering the pump; 3) increasing the flow rate through the waterjet system increased the strength of the streamwise vortex; 4) increasing ramp angle tended to increase the strength of the streamwise vortex; and 5) increasing the fillet radius decreases the strength of the streamwise vortex.

Simulations of steady ahead operation of the waterjet propelled R.V. Athena were also conducted for Froude numbers of 0.34 to 0.84. From these simulations it was found that the pump inflow can be effectively approximated at a new ship speed from a known ship speed by scaling only the mean component of the axial velocity by the relative change in waterjet flow rate. Additionally, waterjet pump operating point and rotor blade inflow angles were found to independent of ship speed.

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7

Levesque, Christopher R. (Chirstopher Robert) 1965. "Vibration suppression in finite length marine cable systems." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47678.

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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.

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8

Tatera, James E. "Vibration reduction of marine cable systems using dynamic absorbers." Thesis, Monterey, California. Naval Postgraduate School, 1996. http://hdl.handle.net/10945/9141.

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9

Cheng, Yongming 1964. "Dynamic stiffness and transfer matrix analysis of marine riser vibration." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/107859.

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10

Kimball, Richard Warren 1963. "Experimental investigations and numerical modeling of a mixed flow marine waterjet." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/91343.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2001.
Includes bibliographical references (leaves 122-126).
Recently, waterjet propulsion has gained great commercial interest as the shipping industry trends toward faster passenger ferries and other fast transport vessels. The work presented in this thesis was part of a larger effort to improve the capabilities and performance of a mixed flow marine waterjet used in such high speed marine applications. An experimental test faciity was constructed and employed in the testing of a mixed flow marine waterjet rotor, stator and housing set. Full description of the facility and waterjet test procedures are discussed. The pumpset was designed using a coupled Lifting Surface/RANS procedure by Taylor et.al.[35] and was built and tested as part of the work presented in this research. Detailed measurements of the pump performance is described including pump curves, tipgap studies, inlet, midstage and outlet velocity and pressure profiles in an axisymmetric inflow. Full accounting for losses including rotor and stator loss profiles as well as a full pumpset energy balance is presented. From the results of the experiment, dominant losses were found near the tip/duct junction casing along with a large and unexpected increase in swirl in this region. Detailed numerical modelling of this pumpset was performed using both a Lifting Surface/RANS procedure and a Lifting Surface/Euler solver. Effects of losses were modelled as well as tipgap effects. Prior work had developed these coupling procedures but the computationally efficient Euler coupling lacked the introduction of loss and drag induced swirl. This loss coupling was added to the model and the analysys results are discussed. Also, a model to align the wakesheet with the local flowfield in the Lifting Surface solver was developed and these results are discussed.
by Richard Warren Kimball.
Ph.D.

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11

Jinkerson, Richard Alan. "Constrained and unconstrained localization for automated inspection of marine propellers." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/25782.

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12

Black, Scott D. (Scott Donald). "Integrated lifting-surface/Navier-Stokes design and analysis methods for marine propulsors." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10398.

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13

Taylor, Todd Eric. "Combined experimental and theoretical determination of effective wake for a marine propeller." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12299.

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14

Coney, William Bowles. "A method for the design of a class of optimum marine propulsors." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14207.

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15

McGee, David Michael. "Experimental studies of fluid-borne noise generation in a marine pump." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/10945/24164.

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16

Kambanis, Leonidas M. Th. "Analysis and modeling of power transmitting systems for advanced marine vehicles." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36067.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1995, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.
Includes bibliographical references (leaves 79-80).
by Leonidas M.Th. Kambanis.
M.S.

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17

Gonzalez, Enrique C. (Enrique Casaprima) 1961. "High frequency dynamic response of marine risers with application to flow-induced vibration." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/107860.

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18

Harrington, Stephanie A. (Stephanie Ann). "New policy protocols for marine scientific research : lessons learned from past case studies." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47680.

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19

Czarnowski, James Taylor. "Exploring the possibility of placing traditional marine vessels under oscillating foil propulsion." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10527.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1997, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997.
Includes bibliographical references (leaves 123-124).
by James Taylor Czarnowski.
M.S.

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20

Bergeron, Nicholas Paul. "Model-Based Control of a High-Performance Marine Vessel." Thesis, University of Louisiana at Lafayette, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1585847.

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This thesis proposes a model-based control of a high performance marine vessel. With this model-based control, comprehensive controls based on the dynamics of the marine vessel will be obtained. The dynamics of the Anaconda, a high performance marine vessel built by Swiftships, Inc., were studied, and equations of motion reflecting the dynamics of the ship were created.

Using the equations of motion, the Anaconda was modeled and multiple point-to-point maneuvers were conducted to predict the movement of the boat in a constant current environment. Transfer functions were developed from the equations of motion and compared to transfer functions obtained from a system identification test done experimentally on the Anaconda to show the validity of the model. The system identification test consisted of a turning and acceleration response.

Using the controls gained from the model-based control, simulated heading changes were compared to experimental heading changes. These same controls were used to perform autonomous waypoint testing with the Anaconda. Since the model-based control was used the Anaconda was able to follow an ideal path relatively closely. A straight line, polygon, circle, and figure 8 autonomous waypoint tracking was performed. The RMS errors were relatively low compared to the errors present in the sensors that were used in measuring the Anaconda's performance.

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21

Lee, Jintae. "A potential based panel method for the analysis of marine propellers in steady flow." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14641.

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22

Miller, Scott Nielsen. "Measurement of vortex-induced oscillations of marine cables using feedback with explicit structural modeling." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38125.

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23

Hanson, Christopher J. (Christopher John) 1971. "Integrated lifting-surface and Euler/boundary-layer theory analysis method for marine propulsors." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/91328.

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Thesis (Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.
Includes bibliographical references (leaves 62-63).
by Christopher J. Hanson.
Nav.E.
S.M.

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Bruce), Laurence Ronald B. (Ronald. "The effect of lubrication system and marine specific factors on diesel engine emissions." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12110.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994.
Includes bibliographical references (p. 63-64).
by Ronald B. Laurence, Jr.
M.S.

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25

Mantzaris, Demetrios Alexis 1968. "A Rankine panel method as a tool for the hydrodynamic design of complex marine vehicles." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50364.

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Alsahlawi, Saad. "Development of a floating wave energy converting breakwater for gulf type marine environment." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49372/.

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With the increase in human activity associated with the recent rise in Kuwait’s oil production, there is greater need for an optimised solution to protect the Kuwaiti coastline and islands from wave attacks and erosion. This thesis describes a programme of research conducted to support the development of a cost-effective method of protecting the Kuwaiti coastline with a breakwater system that also provides an opportunity to generate energy by locally increasing the energy density of waves to make wave energy conversion (WEC) more efficient, cost-effective and commercially competitive. A comprehensive review of the historical development and current state-of-the-art regarding breakwater and WEC technologies is presented. On the basis of these evaluations, a floating breakwater combined with point absorber device is identified as appropriate for use in the Kuwaiti near shore marine environment. The need for increasing the local energy density at the point absorber is highlighted and the concept of using a parabolic concentrator in combination with point absorber is suggested and developed. An analytical study extends the understanding of the role of damping in the response of an idealised point absorber device. A steady-state harmonic model is developed to simulate the motion of a single buoy with one degree of freedom (heave) along the vertical axis to optimise its geometrical and control parameters and maximise its power absorption from incident waves. Evaluating different buoy shapes namely: bullet, spike, and bi-cone (60o/120o) indicates that for each buoy shape, there is an optimum operating range for the power take-off (PTO) that drives the generator where wave energy capture and thus electrical power would be greatest. In the model, comprising a spring-damper system, the PTO is represented as a damper with a constant damping coefficient (〖 c〗_1) and the radiation force is represented by a linear radiation damping term (〖 c〗_2). The model reveals that the best performance is obtained at the optimum value for c_1 which is c_1= c_2=k/ω. This condition is met when the buoy with optimum mass is at resonance with the peak frequency of the sea state at ω^2=k/m. Evaluating the power absorption as a function of 〖 c〗_2 in the model also reveals that at resonance, a buoy of any shape will have two types of behaviour: one driven by low radiation damping and the other by high radiation damping range of values. Operation in the low 〖 c〗_2 region is difficult to achieve in practice, and hence, it is recommended that devices should be designed to operate in the high 〖 c〗_2 region to maximise power capture. Data is presented from wave tank testing conducted using a flume at the Kuwaiti Institute for Scientific Research (KISR). This is used to evaluate the capability of the proposed parabolic concentrator elements to increase potential wave energy harvesting. A wealth of data, both visualisation and numerical, was obtained and this compares well with the computational analyses. The results indicate that a parabola-buoy system would be capable of absorbing almost 260 kW of power at prototype scale (1:16). A computational modelling approach using the commercial CFD code ANSYS-Fluent is developed, applying the volume of fluid approach combined with a wave boundary condition. The KISR wave tank was modelled with parabolic element installed and data is compared to that obtained experimentally. Good agreement between CFD and experimental data is obtained validating the modelling choices made. Additional modelling results for the behaviour of waves near an anchored buoy in combination with a parabolic concentrator are presented. The work presented in this thesis shows that there is the potential for substantial benefit for power absorption through using a combined parabolic concentrator-point absorber device. Future modelling work with fluid-structure interaction and moving buoy will permit further optimisation and development paving the way for full-scale developments in the future.

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Barsikyan, Levon Aleksandrovich. "Effects of high intensity oceanic lightning discharges on the Earth's ionosphere." Thesis, University of Colorado at Denver, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1544242.

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Very Low Frequency (VLF 3-30 kHz) receivers are used to monitor the amplitude and phase of signals from powerful naval VLF communication transmitters. Since the VLF transmitter signals propagate in the Earth-ionosphere waveguide, they provide a method for remotely sensing ionospheric density changes. The effect of powerful natural oceanic lighting discharges on the ionosphere are investigated using VLF remote sensing and the Global Lighting Detection Network (GLD360). Ionospheric disturbances known as Lighting-induced Electron Precipitation (LEP) events and Early/Fast events are investigated. A comprehensive numerical model of the electron precipitation process is used to compare to observation. Results are compared to previous research on lightning effects on the ionosphere.

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Wiberg, Nils Sargent. "Management options for the sustainable development of a common marine resource in Maine : the green sea urchin." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40237.

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Armand, Clotilde. "Damage assessment and liability compensation for marine oil spills : short and long term strategies that achieve international consensus." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42604.

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30

Donnelly, Jessica Mary. "A scatter diagram approach to the selection of design currents for prediction of marine riser vortex-induced vibration." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/33425.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2004.
Includes bibliographical references (leaf 25).
This paper describes a scatter diagram approach for the classification of large numbers of current profiles for use in the prediction of riser fatigue damage due to vortex-induced vibration. Scatter diagrams have long been used to characterize the probability of various combinations of wave height and period, which are then used to assess wave forces. To predict VIV fatigue damage the designer needs to know which current profiles have the combined property of long regions of relatively constant velocity and relatively high speed. A sorting algorithm is proposed which searches every current profile for long regions of relatively constant flow speed. The probability of each length and speed combination is assessed and the data is used to populate the bins of the scatter diagram. The designer need only select relatively few representative profiles for detailed VIV analysis from those bins that would account for the most damage. The method is tested by making comparison to a brute force approach in which each of many thousands of profiles is evaluated for fatigue damage by running it in the SHEAR7 VIV response prediction program.
by Jessica Mary Donnelly.
S.M.

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31

Bradley, Scott. "Benthic lander systems' architecture and a new method for tracking deep-ocean fishes." Thesis, University of Aberdeen, 1998. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602311.

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Deep-ocean (benthic) landers are free-falling vehicles that are deployed from a ship and descend to the ocean floor by virtue of attached ballast. They carry with them scientific instrumentation to carry out in-situ experiments, and once operation is complete, an acoustic command from the surface vessel causes the lander to release its ballast and allow buoyancy to return it to the surface for recovery. Landers function autonomously, typically under the control of a central micro-controller and data-logger. The extreme environment in which landers operate require that all electronics is contained in special pressure housings and interconnection between modules is made using expensive deep-ocean cables and connectors. This thesis presents the concept of a new Controller Area Network (CAN)-based architecture, and a report is given of the development of a miniature network interface board suitable for use on benthic landers. One application of lander technology is in tracking the movements of abyssal fishes that forage close above the ocean floor. Small acoustic transponders are wrapped in bait and attached to the ballast of the lander. Scavenging fish attracted to the bait consume the transponders, after which a sonar system on the vehicle can track their movements. A new method for tracking these fishes is presented that uses a short-baseline hydrophone array mounted on a specially designed lander, AUDOS II. With no moving parts, this method has many advantages over previous systems that relied on scanning directional sonar. Tracking resolution has been greatly improved, and new software tools allow the movements of tracked fish to be viewed quickly and with ease.

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Cunningham, Andrew Donald. "Monte Carlo simulation in the marine environment." Thesis, Liverpool John Moores University, 2011. http://researchonline.ljmu.ac.uk/6001/.

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Yttervik, Rune. "Ocean current Variability in Relation to Offshore Engineering." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-499.

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This work adresses ocean current variability in relation to offshore engineering.

The offshore oil and gas activity has up until recently taken place mainly on the continental shelves around the world. During the last few years, however, the industry has moved past the continental shelf edge and down the continental slope towards increasingly deeper waters. In deep water locations, marine structures may span large spaces, marine operations may become more complicated and require longer time for completion and the effect of the surface waves is diminished. Therefore, the spatial and temporal variability of the current is expected to become more important in design and planning than before.

The flow of water in the oceans of the world takes place on a wide variety of spatial scales, from the main forms of the global ocean circulation (~km), to the microstructure (~mm) of boundary layer turbulence. Similarly, the temporal variability is also large. In one end of the scale we find variations that take place over several decades, and in the other end we find small-scale turbulence (~seconds). Different features of the flow are driven by different mechanisms. Several processes and properties (stratification¹, sloping boundary, Coriolis effect, friction, internal waves, etc.) interact on the continental slope to create a highly variable flow environment. Analysis of a set of observed data that were recorded close to the seabed on the continental slope west of Norway are presented. The data suggest that some strong and abrupt current events (changes in flow speed of ~0.4 m/s in just a couple of hours) were caused by motions of the deep pycnocline², driven by variations in the surface wind field. This conjecture is partly supported by numerical simulations of an idealised continental slope and a two-layer ocean. The data also contains an event during which the flow direction at the sea bed changed very rapidly (within a few minutes) from down-slope to up-slope flow. The change in speed during this event was as high as 0.5 m/s.

Another data set has been analyzed in order to illustrate the spatial variation in the current that can sometimes be found. It is shown that the flow in the upper layer is virtually decoupled from the flow in the lower layer at a location west of Norway. This is either caused by bottom topography, stratification or both.

High variability of the current presents new requirements to the way that the current should be modelled by the offshore engineer. For instance, it is necessary to consider which type of operation/structure that is to be carried out or installed before selecting design current conditions. Reliable methods for obtaining design current conditions for a given deep water location have yet to be developed, only a brief discussion of this topic is given herein.

It is shown, through calculations of VIV-response and simulations of typical marine operations, that the variability of the current will sometimes have a significant effect on the response/operation.

¹Vertical distribution of density. In a stratified ocean or flow, the density of the water varies in the vertical direction.

²pycnocline=density surface between water masses. The pycnocline between two water masses of different density is defined by the maximum of the density gradient.

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34

Fu, Zhu. "Numerical simulation of a centrifuge test related to the interaction between an ice feature and an offshore pipeline." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27844.

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Ice features present one of the major obstacles to offshore development in the Arctic and Atlantic regions of Canada. Ice features have been observed to interact with the see floor creating scour features (Clark et al., 1986). In particular, when an ice feature is driven by environmental forces into the shallow water, ice scouring of the seabed may cause a danger to bottom installations such as submarine pipelines. In the present study, the ice-scour event in a centrifuge test is simulated by using PLAXIS and ADINA finite element programs. The centrifuge test data reported by (Lach et al., 1993; Yang and Poorooshasb, 1997) and the input data in their numerical study are utilized in the present work. In numerical analysis, geometric and material nonlinearities are considered. Two dimensional and three dimensional finite element models are used to calculate the stresses and deformations in the seabed soils, the deflections of the pipe, and the stresses acting on the pipe. In order to establish the validity of the finite element calculations, the experimental results and the numerical results are compared. The importance of using interface elements between the soil and the ice feature is also investigated. The FE predictions are reasonably close to the centrifuge test data. The displacements of the pipe in 3-D model are smaller than those predicted by 2-D model due to the three dimensional effects. Bending and torsion of the pipe along its long axis can only be calculated in 3-D FE analysis. Using the interface elements in the numerical analysis helps to obtain a better agreement between the calculated and measured values. In addition, convergence problems are reduced.

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Baker, Scott. "Physical and numerical modelling of wave interaction with a three-dimensional submerged structure." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27954.

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Submerged structures are frequently used in coastal engineering applications, such as tunnel and pipeline protection works, breakwaters, and artificial reefs. Although a significant number of research works have focused on low-crested structures, there is far less research into deeply submerged structures. In most research, lightly-sloped, uniform cross-sectioned submerged structures with specific crest elevations are considered. The present thesis deals with the three-dimensional physical and numerical modelling of the interaction of irregular waves with a large-scale three-dimensional submerged structure. It aims to advance the understanding of the structure's influence on the irregular wave field, the wave-induced velocities along the structure crest, and the wave-induced currents. The ability of a nonlinear Boussinesq wave model to simulate these processes is also investigated and assessed. Analysis was performed on a multitude of data, including---but not limited to---wave heights, wave periods, wave energy spectra, energy transfer functions, reflection analyses, and wave-induced velocities. In general, the analysis and comparison performed showed that the numerical model provided a modestly accurate representation of the physical modelling results.

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Ahmadi-Nedushan, Behrooz 1966. "Progressive collapse analysis of offshore platforms." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22639.

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This thesis presents a study of the ultimate strength capacity of two offshore platforms located in the Gulf of Mexico. The objective of the study was to validate existing non-linear finite element models for estimating the loads and strength of offshore platforms.
From August 24 to 26 1992, hurricane Andrew moved through the Gulf of Mexico with sustained winds of 140 miles per hour. Thirty-six major platforms suffered significant damage, of these, ten were completely toppled and twenty-six were leaning significantly or had significant topside damage.
Structures "H" and "K" were bridge-connected platforms, located in the ST151 field of the South Timbalier area of the Gulf of Mexico, platform "H" collapsed during Andrew, while "K" survived undamaged. They were both designed, fabricated, and installed in the early 1960's.
A push-over analysis, using the program USFOS was used to estimate the ultimate strength of the two structures in three direction: end-on, diagonal and broadside.
In the first series of analyses, all the primary members such as legs, vertical and horizontal braces, piles, soil, conductors and deck structure were precisely defined with appropriate finite elements as well as secondary members such as conductors guides barge bumpers. In the second series of analyses it was assumed that there was no horizontal or vertical movements at the level of the mudmat. In the third series of analysis the model used in the first series of analysis was modified by increasing stiffness and resistance of the piles 10 times. Finally a fourth model was investigated in which the soil resistance of the mud-level horizontal members is modelled. (Abstract shortened by UMI.)

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Kouadio, Kouassi Serge P. "Durability of fiberglass composite sheet piles in water." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31055.

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With the advance of composite materials in the past 50 years, fiber-reinforced polymer sheet piles are becoming increasingly popular in the marine and waterfront applications. While these materials possess high strength-to-weight ratio and are corrosion resistant, their durability in water has been not well studied due to the lack of historical data for these fairly new materials.
The purpose of this research is to establish the absorption characteristics of a pultruded fiberglass-reinforced polyester composite for a sheet pile wall and quantify the effect of water on long term mechanical properties. The tests conducted were water absorption, tensile strength, flexural strength, and freeze/thaw cycling. An analytical model was developed to establish the nature of the absorption process and prediction of the change in mechanical properties.
The results indicated that the water absorption process of the material followed a combination of Fickian diffusion and polymeric relaxation. The moisture saturation was 1.72% for the flange and 3.11% for web. The absorption process modeling indicated that saturation would be reached in 4.5 years for flange and 7 years for web in tap water, at room temperature. The coefficients of diffusion calculated were 4.2 10-6 mm2/s and 3.0 10-6 mm2/s respectively. During the water absorption test at 70°C and in boiling water, a mass loss of the material occurred. Tensile strength was found to decrease with the increase in percentage of water absorbed with no further degradation seen after saturation was reached. There was a decrease of 60% in the tensile strength at saturation. On the other hand, there was no noticeable change in the tensile modulus of elasticity during the water-ageing period. The freeze/thaw cycling test revealed that there were no significant changes in the tensile strength and the modulus after 564 cycles from 4.4°C to -17.8°C.

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Giroux, Cynthia. "Analysis of the flexural behaviour of a fibreglass composite seawall." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30784.

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Design of fibreglass composite sheet pile seawalls is traditionally based on the flexural rigidity (EI) of the piling system. To compare with commonly used steel or wood sheet piling, there is a strong need to properly characterise the flexural behaviour of composite piling systems. Directed by this industrial need, the research reported herein is focused on the flexural response of a pultruded sheet pile seawall panel consisting of E-glass fibre-reinforced polyester. The analysis consists of an experimental investigation, analytical modelling, and finite element simulation to determine the flexural and shear rigidities of the seawall panel for use in computing the deflections of the piling system.
A novel testing method was developed to simultaneously determine the flexural rigidity (EI) and shear rigidity (kAG) of the panel using Timoshenko's beam theory. Three- and four-point bending tests were performed on six different span lengths and the results were self-consistent from the two different tests. (Abstract shortened by UMI.)

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39

Li, Xiaoyan 1963. "Coagulation between fractal aggregates and small particles and fractal properties of marine particles." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282174.

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This dissertation includes two parts (designated A and B) that serve two separate but related research purposes. In Part A, coagulation rates between fractal aggregates (200-1000 μm) and small (1.48 μm) particles were studied for collisions induced by differential sedimentation and turbulent fluid shear. The collision frequency functions (beta) between these aggregates and small particles were found to be lower than predicted by a rectilinear collision model but much higher than predicted by a curvilinear collision model for equivalent impermeable spheres. The collision frequencies decreased with the magnitude of aggregate fractal dimensions (D). Based on fractal geometry of aggregates and the comparisons between observed settling velocities and those calculated using Stokes' law, a semi-empirical correlation was derived to describe the permeabilities of settling fractal aggregates. A filtration model was used in conjunction with this fractal permeability correlation to predict capture rates and capture efficiencies of small particles by settling fractal aggregates. In the turbulently sheared fluid, it was demonstrated that the importance of the shear rate (G) on enhancing collision frequencies was dependent on the fractal dimension of aggregates. As D approaches 3, beta became less sensitive to G as predicted by a curvilinear model. It was argued that flow through large pores formed between clusters within fractal aggregates contributed to high aggregate permeabilities and enhanced the coagulation between the aggregates and suspended small particles. In part B, fractal properties of microscopic particles (300 μm) occurring in marine systems were investigated. A new method, called the particle concentration technique (PCT), was developed to calculate the average fractal dimension of all particles in a certain size range by the analysis of particle size distributions in terms of both solid volume and length. During a simulated algae bloom in a mesocosm, as coagulation proceeded the average fractal dimension decreased with time from D = 2.52 to D = 1.68, a value typical of larger marine snow aggregates. Investigations in three eastern Pacific coastal areas suggested that the average fractal dimension indicated the importance of coagulation in determining local particle size distributions. The magnitude of the fractal dimension is likely associated with other factors, such as transparent exopolymer particles (TEP), affecting the coagulation rate of algae during a bloom in seawater.

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40

Boppe, Ravi Shankar. "Quasi-coherent structures in the marine atmospheric boundary layer." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09292009-020027/.

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Rutan, Ronald J. (Ronald James) 1965. "Marine applications of power supply and conditioning interfaces for high power pulse devices." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/91374.

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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 Electrical Engineering and Computer Science, 2002.
Includes bibliographical references (leaves 96-102).
by Ronald J. Rutan.
S.M.in Naval Architecture and Marine Engineering
S.M.

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Marr, Gregory Paul. "An investigation of Neumann-Kelvin ship wave theory and its application to yacht design." Thesis, University of Auckland, 1996. http://wwwlib.umi.com/dissertations/fullcit/9610750.

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Wave drag significantly affects ship powering and speed prediction calculations, and the performance of sailing yachts. Linear Neumann-Kelvin ship wave theory is taken as a starting point for the development of a computational approach for predicting water flow about yacht hulls. Previous work by Baar and Price, Newman, and Doctors and Beck for the calculation of the Kelvin source and its derivatives and their use with panel methods is repeated, refined and extended. Consistent and accurate results are obtained for numerical tests and Farell's submerged spheroid test cases. Baar and Price's results for the Wigley hullform (which compare well with experiments) were not able to be duplicated in the present study, despite significant tests of both local and integrated solution values. The tests did indicate that the current implementation was behaving correctly, and gave wave resistance results equivalent to those from Doctors and Beck's study, to a level of agreement which contrasted sharply with the wide scatter in Chen and Noblesse's survey. These results remove to some extent numerical inaccuracies as a postulated source of the theory's difficulties, leaving the conclusion that Neuman-Kelvin theory, as it is currently understood, does not give satisfactory wave resistance results for realistic ship hullforms. These and further results lead to, and reinforce, the suggestion that the problem lies with the waterline integral term; a new treatment of this term may substantially increase the applicability of Neumann-Kelvin theory. The extensions required for modelling sailing yachts are considered. Investigation of three yacht design problems show that the developed model can predict, and partly explain, previously observed free surface effects. These 'relative' effects may be adequately predicted even though the absolute results appear less reliable. For the simplified parabolic yacht hullform tested, the sideforce is relatively constant over the speed range generally relevant to upwind sailing, and well modelled by the (zero Froude number) cosine squared (heel angle) relationship. The effects of a bulb, and heel (for the Wigley hullform), on wave resistance are shown. Suggestions for further work, calculation details, and tables of wave resistance and Kelvin source (and gradient) values are given.
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McGuire, Heather L. "The Effects of Shading by Open-Pile Structures on the Density of Spartina alterniflora." W&M ScholarWorks, 1990. https://scholarworks.wm.edu/etd/1539617618.

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Proft, Heinz Michael. "Impact of Artificial Reef Associates on Macrobenthic Community Structure in Florida Bay." W&M ScholarWorks, 1995. https://scholarworks.wm.edu/etd/1539617691.

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Adams, Aaron J. "Dynamics of Fish Assemblages Associated with an offshore Artificial Reef in the Southern Mid-Atlantic Bight." W&M ScholarWorks, 1993. https://scholarworks.wm.edu/etd/1539617663.

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McGookin, Euan William. "Optimisation of sliding mode controllers for marine applications : a study of methods and implementation issues." Thesis, University of Glasgow, 1997. http://theses.gla.ac.uk/3980/.

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The optimisation of Sliding Mode controllers for marine vehicle guidance is presented in this thesis. This study is concerned with two optimisation methods which are based on natural processes. The first is Simulated Annealing which involves processes analogous to those involved in the cooling process in metallurgy. The second involves Genetic Algorithms which are based on the evolutionary process of species and genetics. These methods are evaluated through studying their application to the optimisation of controller parameters for particular marine vessels. Their performance is measured through simulation studies during the optimisation process. Existing literature in the fields of the two optimisation techniques, Sliding Mode control and marine control is surveyed. The theory of Simulated Annealing is presented in terms of the optimisation process and its convergence properties through Markov Chain analysis. A novel variation of this method, Segmented Simulated Annealing, is also outlined and evaluated in terms of its improved convergence properties. The theory of Genetic Algorithms is presented in terms of its process and convergence properties using Markov Chains and the Schema Theorem. The derivation of a decoupled Sliding Mode control theory is described and its well known stability robust properties are ensured by the choice of an appropriate set of design criteria. The elimination of the chattering phenomenon is achieved by soft switching which ensures performance robustness. The application of Sliding Mode controllers for governing the motion of three marine vehicles and their subsequent optimisation is presented. The first is the simulation of a linear mathematical representation of a military submarine. The second is the simulation of a non-linear mathematical representation of a super tanker. The third is an actual scale model of a supply ship which enables evaluation of the optimised controllers in a laboratory water basin facility.

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Mills, Louis Van Orden 1949. "Marine scenic resource assessment: An international perspective." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282537.

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The focus of this research was the practical application, inventory, and analysis of scenic resources of the marine environment. From an international perspective, the concept of establishing marine parks and preserves was traced and shown to be a recent phenomenon in an effort to protect pristine and unique marine areas. Unfortunately, the inclusion of marine scenic resources as a distinct element in the site planning and site design management process is at present negligible. This research presents a systematic scenic resource inventory and scenic preference testing using the Q-sort method of underwater photographic examples from three case study areas: Key Largo National Marine Sanctuary, Florida, St. Croix, US Virgin Islands and Jervis Bay, New South Wales Australia. Over three hundred volunteers rated fifteen underwater photographs from each case study area in an attempt to determine the predictive factors for scenic resource quality. Demographic information was collected from each volunteer in terms of sex, age, occupation, education, place of residence and diving experience. These background characteristics were evaluated in terms of their effect on scenic preference ratings using correlation analysis. It was demonstrated that these background factors had no significant influence on scenic preference rating. Nine seascape dimensions were selected and analyzed using multiple regression to determine if certain physiographic variables influenced preference rating. It was determined that color, marine fauna, marine flora, and water clarity were the most influential factors affecting scenic preference rating. Based on these scenic preference results, a proposed site management plan was demonstrated for each case study that could be a model for future scenic resource assessment.

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Chen, Shih-Tzung. "Qualitative and quantitative analysis of marine accidents using a human factor framework." Thesis, Liverpool John Moores University, 2010. http://researchonline.ljmu.ac.uk/5956/.

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Eleye-Datubo, Adokiye Godwill. "Integrative risk-based assessment modelling of safety-critical marine and offshore applications." Thesis, Liverpool John Moores University, 2005. http://researchonline.ljmu.ac.uk/5806/.

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This research has first reviewed the current status and future aspects of marine and offshore safety assessment. The major problems identified in marine and offshore safety assessment in this research are associated with inappropriate treatment of uncertainty in data and human error issues during the modelling process. Following the identification of the research needs, this thesis has developed several analytical models for the safety assessment of marine and offshore systems/units. Such models can be effectively integrated into a risk-based framework using the marine formal safety assessment and offshore safety case concepts. Bayesian network (BN) and fuzzy logic (FL) approaches applicable to marine and offshore safety assessment have been proposed for systematically and effectively addressing uncertainty due to randomness and vagueness in data respectively. BN test cases for both a ship evacuation process and a collision scenario between the shuttle tanker and Floating, Production, Storage and Offloading unit (FPSO) have been produced within a cause-effect domain in which Bayes' theorem is the focal mechanism of inference processing. The proposed FL model incorporating fuzzy set theory and an evidential reasoning synthesis has been demonstrated on the FPSO-shuttle tanker collision scenario. The FL and BN models have been combined via mass assignment theory into a fuzzy-Bayesian network (FBN) in which the advantages of both are incorporated. This FBN model has then been demonstrated by addressing human error issues in a ship evacuation study using performance-shaping factors. It is concluded that the developed FL, BN and FBN models provide a flexible and transparent way of improving safety knowledge, assessments and practices in the marine and offshore applications. The outcomes have the potential to facilitate the decision-making process in a risk-based framework. Finally, the results of the research are summarised and areas where further research is required to improve the developed methodologies are outlined.

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Tayebi, Noosha. "Identification and characterization of a cost-effective combination of systems for Arctic surveillance: The Northern Watch project." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28425.

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This thesis discusses a new stream of research and analysis which will form part of the Northern Watch Technology Demonstration project. The objective of the thesis is to develop and illustrate a procedure for identifying and characterizing combinations of sensors and systems that will provide cost-effective options for Arctic maritime surveillance. A ship detection simulation is constructed, the results of which are used to produce a set of ranked options for combinations of sensors used to conduct maritime surveillance at a strategic choke point located at the Barrow Strait, in Canada's Northwest Passage. The overall objective of the surveillance is to improve on the detection, classification, and identification of maritime vessels. The modeled performance and effectiveness of each sensor is evaluated in relation to the multiple objectives using the Analytical Hierarchy Process (AHP) to rank alternative sensor effectiveness and performance. The results indicate that the most cost-effective solution is to install an Automatic Identification System (AIS) sensor at the Northern Watch station. However, due to practical concerns, alternatives to this approach are presented and discussed.

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Dissertations / Theses on the topic 'Marine and Ocean Engineering'

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