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1
Park, Jin-Soo. "Marine traffic engineering in Korean coastal waters." Thesis, University of Plymouth, 1994. http://hdl.handle.net/10026.1/2410.
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This study describes and discusses the marine casualties, the effectiveness of existing traffic services, and marine safety and Vessel Traffic Service(VTS) in Korean coastal waters. Marine traffic is comprehensively assessed in Korean waters, an analysis of casualties is undertaken by block scheme. Marine environmental parameters are identified relating to marine casualties as appropriate. Various statistical techniques are employed to evaluate the inter-relationships between individual causal factors, and for the first time effect level is instituted to quantify the relative importance of the causal factors in Korean waters. A further innovation is the examination of the adequacy of existing Korean traffic services by casualty and traffic analysis, and an accident danger index is introduced to compare accident danger over different .time periods. A mixed population of contributors to marine safety is sought by questionnaire. The design of this is both innovative and original in content in order to evaluate the perceived importance of the various risk factors, the marginal effectiveness of various options in reducing risks, and their weight with regard to YTS services and activities, the main part of the study uses an original multiple coefficient to estimate casualty reduction rate and a new method to quantify the effectiveness of VTS. The Korean waters traffic study is conducted as an intermediate level and provides the data base for the main body of work. The conclusions include recommendations with respect to the stricter enforcement of the routeing scheme(TSS) and the adoption of further traffic observation/surveillance over the areas concerned. Finally it is noted in particular that additional Vessel Traffic Service and Traffic Separation Schemes are now required if any substantial improvement is to be achieved in marine traffic safety in Korean coastal waters.
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Kahkeshan, Siavoche. "Marine log supply : a transport engineering analysis." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27117.
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This thesis investigates the marine transport-inventory system of Coastal British Columbia.
The intrinsic characteristics of marine log transportation in this region are the vulnerability of marine transportation to adverse weather conditions and the presence of time-related economic costs.
The system is confined to the Powell River operation. Three origins, one storage area and three pulp log types are considered. The formulated problem is classified as a sequential decision-making process. A deterministic model using the network flow theory and a simulation model using GPSS are developed. Due to considerable uncertainty in the system operation, the computer simulation model is selected.
The model includes all of the important system variables and their interactions and assesses alternative operational doctrines by calculating variation in a key aspect of system performance, total logistic cost.
It is found that: 1) the use of barges as the transportation mode leads to the least logistic cost, 2) the second best transportation alternative is the direct shipment of logs from origins to the mill and 3) if higher value saw log is considered, the log-taxi alternative may become attractive.
However, to improve the capability of the developed model, more information on the salt contamination and teredo damage and accurate estimation of cost consequences of a mill shutdown are required. Future works should focus on these areas.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Yang, Y.-S. "Marine hazard assessment." Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356793.
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Abujaafar, Khalifa Mohamed. "Quantitative human reliability assessment in marine engineering operations." Thesis, Liverpool John Moores University, 2012. http://researchonline.ljmu.ac.uk/6115/.
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Marine engineering operations rely substantially on high degrees of automation and supervisory control. This brings new opportunities as well as the threat of erroneous human actions, which account for 80-90% of marine incidents and accidents. In this respect, shipping environments are extremely vulnerable. As a result, decision makers and stakeholders have zero tolerance for accidents and environmental damage, and require high transparency on safety issues. The aim of this research is to develop a novel quantitative Human Reliability Assessment (HRA) methodology using the Cognitive Reliability and Error Analysis Method (CREAM) in the maritime industry. This work will facilitate risk assessment of human action and its applications in marine engineering operations. The CREAM model demonstrates the dynamic impact of a context on human performance reliability through Contextual Control Model controlling modes (COCOM-CMs). CREAM human action analysis can be carried out through the core functionality of a method, a classification scheme and a cognitive model. However, CREAM has exposed certain practical limitations in its applications especially in the maritime industry, including the large interval presentation of Human Failure Probability (HFP) values and the lack of organisational factors in its classification scheme. All of these limitations stimulate the development of advanced techniques in CREAM as well as illustrate the significant gap between industrial needs and academic research. To address the above need, four phases of research study are proposed. In the first phase, the adequacy of organisation, one of the key Common Performance Conditions (CPCs) in CREAM, is expanded by identifying the associated Performance Influencing Factors (PIFs) and sub-PIFs in a Bayesian Network (BN) for realising the rational quantification of its assessment. In the second phase, the uncertainty treatment methods' BN, Fuzzy Rule Base (FRB) , Fuzzy Set (FS) theory are used to develop new models and techniques' that enable users to quantify HFP and facilitate the identification of possible initiating events or root causes of erroneous human action in marine engineering operations. In the third phase, the uncertainty treatment method's Evidential Reasoning (ER) is used in correlation with the second phase's developed new models and techniques to produce the solutions to conducting quantitative HRA in conditions in which data is unavailable, incomplete or ill-defined. In the fourth phase, the CREAM's prospective assessment and retrospective analysis models are integrated by using the established Multiple Criteria Decision Making (MCDM) method based on, the combination of Analytical Hierarchical Process (AHP), entropy analysis and Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS). These enable Decision Makers (DMs) to select the best developed Risk Control Option (RCO) in reducing HFP values. The developed methodology addresses human actions in marine engineering operations with the significant potential of reducing HFP, promoting safety culture and facilitating the current Safety Management System (SMS) and maritime regulative frameworks. Consequently, the resilience of marine engineering operations can be further strengthened and appreciated by industrial stakeholders through addressing the requirements of more safety management attention at all levels. Finally, several real case studies are investigated to show end users tangible benefits of the developed models, such as the reduction of the HFPs and optimisation of risk control resources, while validating the algorithms, models, and methods developed in this thesis.
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Mosaad, Mohamed Ahmed Abdel-Rahman. "Marine propeller roughness penalties." Thesis, University of Newcastle Upon Tyne, 1986. http://hdl.handle.net/10443/1006.
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The main objective of the project is to investigate the influence of surface roughness of marine propeller blades on propulsive power. The work has involved studies in the concept and practice of surface roughness measurement and characterisation as well as application of boundary layer theory for the analysis propeller-ship hull flow interaction of propeller flow and propellar-ship hull flow interaction. From extensive measurements of the surface topography of in-service propellers, a standard measurement procedure using different commercially available propeller-surveying instruments is described. A development of turbulent boundary layer procedures has been made to determine sufficiently accurately the increment of drag coefficient of propeller blade sections due to propeller blade surface roughness. The roughness function used for this integral boundary layer analysis is derived using, principally, Musker's experimental data. In addition, an experimental determination of the roughness function of a replicated propeller surface using a rotor apparatus has been carried out and described in detail. The turbulent boundary layer procedures require a knowledge of the surface variation of pressure over the propeller blade. For this purpose a program based on Riegels method has been used to give the velocity distribution for a given propeller section geometry. This is used with the boundary layer procedures for developing a complete program "PROFNESS" to calculate the increment of drag coefficient of the blade section. Results from different propellers analysed indicate that the power penalty is proportional to the relative blade roughness to the 1/3 power. An investigation has been made to compare the increment of frictional coefficient for a flat plate and propeller section profiles. It is shown that a "rough" flat plane calculation is quite adequate for such work.' The use of a flat plate analogue as a reference to calculate the skin friction resistance of both propeller and hull surfaces is considered. It is shown that the proposed solution of flat plate momentum integral equations provides a valid, simple and practical solution to the problem of predicting the hull and propeller roughness drag penalties. It also provides, particularly for ship hull resistance, a strong support for the ITTC Correlation Line, not only, and importantly, in regard to its slope, but also its level. For shipowners and operators who may not wish to access advanced computer programs, a simplified method has been proposed to calculate the propeller roughness penalties. There is a good agreement between the two simplified and detailed propeller analysis methods. The propeller roughness penalties, which can be obtained from either the simplified or the more rigorous method, can be related to the Rubert Propeller Comparator Gauges in order to quantify the benefits and justify the cost of the blade surface roughness. Analytical procedures have been included which can be used to calculate the combined effects on ship performance of propeller blade and ship hull surface roughnesses.
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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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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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Son, Kwangmin. "Physical ecology of marine microbes." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100148.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references.
Marine microbes play a fundamental role in driving ocean ecosystem dynamics and biogeochemistry. While their importance is global in scale, microbial processes unfold at the level of single cells and are intimately dependent on interactions between microorganisms, their neighbors, and the surrounding physical and chemical environment. Furthermore, traditional imaging techniques often provide frozen snapshots of the marine microbial world, yet microbial interactions are inherently dynamic, as for example in the case of motility, chemotaxis, and the encounter of microbes with viruses and animal hosts. These biological processes are frequently driven by physical mechanisms, and our understanding of them can benefit from a focus on the physical ecology of marine microbes. This is the approach pursued in this thesis, by directly applying dynamic imaging and microfluidics, which offer powerful new opportunities to study microbial processes in a time resolved manner and with exquisite environmental control. Through single-cell, live imaging of three fundamental marine microbial processes - motility, chemotaxis and viral adsorption - we demonstrate how capturing previously unseen biophysical processes in microbial ecology at their natural timescales can both shed light on unexplained mechanisms and provide robust quantifications of interaction rates. We first study a newly discovered nanoscale motility adaptation in the marine bacterium Vibrio alginolyticus using high-speed imaging. We found that marine bacteria can exploit a buckling instability of their flagellum to change direction during swimming, achieving the same functionality as multi-flagellated cells, but with the cost of synthesizing and operating only one flagellum. This finding not only reveals a new role of flexibility in prokaryotic flagella, but also highlights the exquisite motility adaptations of marine microbes to the resource-poor environment of the ocean. We then determine how this motility adaptation affects the cells' ability to climb chemical gradients ('chemotaxis'). We found that, counter- to current models, chemotaxis in V. alginolyticus is speed-dependent. Faster cells exhibited not only faster chemotactic migration, but also tighter accumulation around the resource peak. This result adds a new dimension to our understanding of bacterial chemotaxis pathways, by demonstrating that swimming speed can be an important and counter-intuitive control parameter in how marine microbes encounter and exploit chemical resources. Finally, we consider an encounter process that is motility-independent - that between a nonmotile host and a virus. Using the globally abundant marine cyanobacterium Prochlorococcus and a cyanobacterial virus ('cyanophage') as a model system, we directly imaged the encounter and adsorption dynamics of the virus and the host at the level of single cells, using dual-wavelength epifluorescent microscopy. By applying this non-invasive approach to quantify thousands of encounter events using automated image acquisition and analysis, we directly measured the rate at which viruses encounter and adsorb to hosts. We found that the probability of adsorption is considerably lower than was obtained with traditional, bulk measurement approaches, suggesting the need for a revision of viral infection dynamics in marine ecosystem models and opening the door for studies of microbial individuality in the context of viral infection. In summary, this thesis demonstrates that physical processes in microbial ecology, studied by means of new approaches including microfluidics and dynamic imaging at the single-cell scale, can contribute fundamental new insights into the ecology of marine microbes.
by Kwangmin Son.
Ph. D.
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So, Tze-chung, and 蘇子頌. "Engineering behaviour of Hong Kong marine clay during vacuum preloading." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41634147.
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MartiÌnez, JoaquiÌn MartiÌnez. "Molecular ecology of marine algal viruses : relevance to tissue engineering." Thesis, University of Plymouth, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434307.
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So, Tze-chung. "Engineering behaviour of Hong Kong marine clay during vacuum preloading." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41634147.
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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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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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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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Bornschein, Arthur W. Jernigan Michael. "Re-engineering the United States Marine Corps Special Education Program (SEP) /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA345981.
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Thesis (M.S. in Information Technology Management) Naval Postgraduate School, March 1998."March 1998." Thesis advisor(s): Hemant Bhargava, Suresh Sridhar, Tim Phillips. Includes bibliographical references (p. 179-182). Also available online.
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Koch, Gary D. "Re-engineering the United States Marine Corp's Enlisted Assignment Model (EAM) /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA350140.
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Thesis (M.S. in Information Technology Management) Naval Postgraduate School, June 1998.Thesis advisor(s): Hemant Bhargava, Suresh Sridhar. "June 1998." Includes bibliographical references (p. 129-130). Also available online.
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Koch, Gary D. Jr. "Re-engineering the United States Marine Corp's Enlisted Assignment Model (EAM)." Thesis, Monterey, California. Naval Postgraduate School, 1998. http://hdl.handle.net/10945/26723.
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Approved for public release, distribution is unlimitedIn a time of downsizing and budgetary constraints the Manpower division of Headquarters, United States Marine Corps, accomplishes its mission to put the right Marine in the right place at the right time with the right skills and quality of life" in a variety of ways. Currently, one of the processes that assist the Marine Enlisted Assignments branch is the Enlisted Assignment Model. The current system is not producing the results that are needed and the current managers do not tmst the output. This thesis proposes changes to the EAM user interface, data access, and data storage capabilities to enable the Marine Corps to use the latest information technology to more closely mirror the vision as stated above. With the use of Business Process Reengineering, Process Modeling, and Database Design a prototype is developed to address areas of the current system that can be changed. By using these methods to ensure an appropriate interface with optimization techniques, a complete Decision Support System for manpower assignments can be realized. These changes will empower managers to effectively and efficiently manage, not just monitor manpower readiness in order to meet the challenges of the 2l% century.
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Bornschein, Arthur W., and Michael Jernigan. "Re-engineering the United States Marine Corps Special Education Program (SEP)." Thesis, Monterey, California. Naval Postgraduate School, 1998. http://hdl.handle.net/10945/8898.
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Approved for public release; distribution unlimited.Within the United States Marine Corps, there exist billets (jobs) that require specialized graduate education. Department of Defense agencies submit requests to add billets to their organizational structure. Marine Corps Orders require for every billet added another must be removed elsewhere to balance manpower requirements. Additionally, continuing validation of the billets is required to ensure compliance with Secretary of Defense criteria. Problems in the key function, billet validation, include inflexible, inefficient, and ineffective processes, and nebulous validation criteria. We address these problems by developing a centralized decision support system to be used in a distributed collaborative setting. The objectives of the Special Education Program (SEP) Billet Validation System are to allow SEP billet holders and commands to evaluate and justify existing SEP billets, to assist Military Occupational Specialty Sponsors in identifying manpower reductions, and to validate the graduate education requirement for existing SEP billets. Methods from Multi-Criteria Decision Making (MCDM) (specifically Multi-Attribute Utility Theory (MAUT) and the Analytical Hierarchy Process (AHP)) are used to formalize Secretary of Defense requirements and quantify relative ratings of billets. The system employs a Web Browser front-end application to allow the administrative review process to be performed in a parallel manner
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Whitcher, Alan. "Situation awareness of marine control room operators." Thesis, Southampton Solent University, 2013. http://ssudl.solent.ac.uk/3002/.
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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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Castellanos, Samantha Nicole. "Casting a one-lunger Atlantic marine engine." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105712.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (page 39).
Fabrication of a one-lunger Atlantic marine engine for the purposes of developing a curriculum for an advanced fabricating and machining class for the Papplardo Apprentices at MIT. One-lunger marine engines greatly influenced the fishing cultures of Nova Scotia at the turn of the 20th century. Discussion of proper casting practices and terminology in addition to theory of sand types, machinability, engine cycles, and ignition systems. In depth descriptions of basic and advanced casting processes using the ignitor body and piston as examples.
by Samantha Nicole Castellanos.
S.B.
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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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Ventouras, Laure-Anne. "Iron and the ecology of marine microbes." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/80257.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2013Cataloged from PDF version of thesis.
Includes bibliographical references.
Iron is a cofactor of a number biochemical reactions that are essential for life. In the marine environment, this micronutrient is a scarce resource that limits processes of global importance such as photosynthesis and nitrogen fixation. Given that marine microorganisms play a central role in modulating such biogeochemical cycles, understanding how their distribution, diversity and activity may be affected by changes in iron availability is key. This thesis explores how the availability of iron affects the ecology of marine microbial populations and communities. At the population level, I characterized the prevalence and diversity of iron acquisition strategies in specific populations of marine vibrios with distinct micro-habitat preferences. Using a combination of genomics and functional screens, I showed that siderophore-based iron acquisition is not conserved at the organismlevel but represents a stable trait at the population level. This population-level trait further appears to play a role in driving the diversification of specific vibrio populations, especially of those that are thought to prefer particles as a micro-habitat. At the community level, I measured whole microbial community responses to iron addition in microcosm experiments in different regions of the Pacific Ocean. Using metagenomics, I characterized the impact of iron availability on the microbial community structure of the Central Equatorial Pacific Ocean. This study showed that addition of iron to an iron-limited ecosystem triggers a phytoplankton bloom dominated by Pseudo-nitZschia-like diatoms, which in turn stimulate a Bacteroidetes population functionally distinct from the ambient free-living population. In the North Pacific Subtropical Gyre, I explored how iron availability impacts microbial community gene expression dynamics. Using a metatranscriptomic approach I showed that in that environment, the impact of iron was tightly connected to the supply of other limiting macronutrients, and seems to mostly affect photosynthetic organisms. This initial study paves the way for more in depth and longer-term studies to further investigate the effects of iron on the dynamics of the microbial community in the North Pacific Subtropical Gyre. Taken together data and analyses presented in this thesis demonstrate how iron availability can shape the ecology of marine microorganisms at population, community and functional levels.
by Laure-Anne Ventouras.
Ph.D.
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Rossouw, T. J. "The underwater separation of diamantiferous marine gravels." Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/8312.
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Includes bibliography.Three underwater separation devices have been designed, constructed, tested and analysed to determine their suitability for the underwater separation of diamantiferous marine gravels. The research facility where the devices were tested was constructed at the University of Cape Town's Hydrotransport Research facility. The first device tested was a converging elutriator which separates the oversize gravel from the smaller diamond-bearing gravel, using their varying particle settling velocities in an upward flowing fluid. The cyclosieve and spirosieve are two other choices that both use rotational flow to create a centrifugal force, which forces the gravel onto a screening surface. The test work carried out investigated the effect of various variable parameters on the separation efficiency of each device.
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Pinto, Waldir Terra. "On the dynamics of low tension marine cables." Thesis, University College London (University of London), 1995. http://discovery.ucl.ac.uk/1317622/.
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This thesis is concerned with the dynamics of low tension marine cables. These cables are widely used in the ocean environment for signal and power transmission applications. There are two main issues in the dynamic analysis of such cables. When the tension is zero, which is often the situation encountered at the seabed during cable laying, the cable geometric stiffness matrix becomes singular. The other issue is that the transformation from local co-ordinates to global co-ordinates made through Euler angles leads to a greater number of unknowns than the number of differential equations. The former problem can be overcome by taking into account the flexural rigidity of the cable. The latter problem can be overcome by assuming that one of the Euler angles is known. However, this procedure can introduce singularities on the formulation of the problem. A new three dimensional model for the dynamics of marine cables is presented in this thesis. The model takes into account the bending stiffness of the cable in order to overcome singularities in the geometric stiffness matrix. In order to overcome the problem owing to the use of Euler angles, a new displacement approach is introduced. This new displacement approach uses the differential geometry definition of curvature and torsion in order to establish the transformation from the local co-ordinates to the global co-ordinates. The general formulation of the dynamics of marine cables presented in this thesis is applicable to a wide range of cases such as towed cables, cable installation and cable recovery. In order to illustrate this new formulation the cases of towed cables and cable installation are investigated in the some detail. Solutions for the differential equations of motion are presented for two and three dimensions. The two dimensional solution is obtained through a finite element based technique which uses a weak Galerkin formulation for integration in space and the Newmark method for integration in time. The model's results are compared with full scale measurements. Simulations of the dynamic response of marine cables to vessel wave induced motions and vessel changes in speed are also presented. The three dimensional solution is obtained by expressing the equations of motion as functions of the Euler angles. The space integration is also performed by a finite element model but it uses a finite difference scheme for the time integration. This solution is then used to study the influence of sheared cross-currents in the cable's configuration. Finally, conclusions and suggestions for further research are presented.
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Ma, Yong Feng. "Characterization of Macau marine deposits." Thesis, University of Macau, 2008. http://umaclib3.umac.mo/record=b1943027.
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Leavitt, Joseph William. "Intent-aware collision avoidance for autonomous marine vehicles." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/111893.
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Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 259-278).
Applications of autonomous marine vehicles in dynamic and uncertain environments continuously grow as research unveils new enabling technology and academic, commercial, and government entities pursue new marine autonomy concepts. The safe operation of these vehicles in the marine domain, which is currently dominated by human-operated vehicles, demands compliance with collision avoidance protocol, namely the International Regulations for Preventing Collisions at Sea (COLREGS). Strict application of this protocol can lead to a highly constrained motion planning problem, in which it is difficult for a vehicle to identify a safe and efficient motion plan. This thesis proposes a multi-objective optimization-based method for COLREGS-compliant autonomous surface vehicle collision avoidance in which vehicles use shared intent information, in addition to vehicle state information, to identify safe and efficient collision avoidance maneuvers. The proposed method uses intent information to relax certain COLREGS-specified constraints with the goal of providing sufficient maneuvering flexibility to enable improvements in safety and efficiency over a non-intent-aware system. In order to arrive at an intent-aware solution, this thesis explores the concept of intent, including intent formulations for the marine domain, intent communications, and the application of intent to the COLREGS-compliant motion planning problem. Two types of intent information are specifically evaluated: COLREGS mode intent, in which the give-way vessel in an overtaking or crossing scenario communicates its intent to maneuver in a certain direction with respect the stand-on vessel, and discrete trajectory intent in which vehicles communicate projected future positions. Simulations and on-water experiments demonstrate the feasibility of the proposed intent-aware method, as well as improvements in performance, in terms of both vehicle safety and mission efficiency, over a non-intent-aware, COLREGS-compliant collision avoidance method.
by Joseph William Leavitt.
Nav. E.
S.M.
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Leavitt, Joseph William. "Intent-aware collision avoidance for autonomous marine vehicles." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111893.
Full textAbstract:
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 259-278).
Applications of autonomous marine vehicles in dynamic and uncertain environments continuously grow as research unveils new enabling technology and academic, commercial, and government entities pursue new marine autonomy concepts. The safe operation of these vehicles in the marine domain, which is currently dominated by human-operated vehicles, demands compliance with collision avoidance protocol, namely the International Regulations for Preventing Collisions at Sea (COLREGS). Strict application of this protocol can lead to a highly constrained motion planning problem, in which it is difficult for a vehicle to identify a safe and efficient motion plan. This thesis proposes a multi-objective optimization-based method for COLREGS-compliant autonomous surface vehicle collision avoidance in which vehicles use shared intent information, in addition to vehicle state information, to identify safe and efficient collision avoidance maneuvers. The proposed method uses intent information to relax certain COLREGS-specified constraints with the goal of providing sufficient maneuvering flexibility to enable improvements in safety and efficiency over a non-intent-aware system. In order to arrive at an intent-aware solution, this thesis explores the concept of intent, including intent formulations for the marine domain, intent communications, and the application of intent to the COLREGS-compliant motion planning problem. Two types of intent information are specifically evaluated: COLREGS mode intent, in which the give-way vessel in an overtaking or crossing scenario communicates its intent to maneuver in a certain direction with respect the stand-on vessel, and discrete trajectory intent in which vehicles communicate projected future positions. Simulations and on-water experiments demonstrate the feasibility of the proposed intent-aware method, as well as improvements in performance, in terms of both vehicle safety and mission efficiency, over a non-intent-aware, COLREGS-compliant collision avoidance method.
by Joseph William Leavitt.
Nav. E.
S.M.
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Pullen, Roger. "Poly(itaconate) esters as marine antifoulants." Thesis, Southampton Solent University, 1998. http://ssudl.solent.ac.uk/2436/.
Full textAbstract:
A series of fluorinated and non-fluorinated poly(mono- and diitoaconate)s and a perfluorinated acrylate, poly(2-(N-ethylperfluorooctanesulfanamido)ethyl acrylate) have been synthesised, by both solution and bulk chain growth polymerisation methods, characterised and some of their properties (thermal behaviour, surface energy and marine antifouling peformance) have been investigated. Chemical structures were confirmed by Gourier-transform infrared (FTIR) and nuclear magnetic resonance (1H & 13C NMR) spectroscopies, as well as mass spectrometry. Poly(itaconate)s prepared by solution chain growth polymerisation resulted in low average relative molecular mass (Mw <15000), whereas those prepared by bulk chain-growth polymerisation were of high average molecular mass (Mw ca 60000). The thermal degradation behaviour of polu(monoitaconate)s, Mwca60000, was dominated by dehydration/de-esterification reaction at ca 170 deg.C which yielded a poly(anhydride) structure. Poly(diitaconate)s Mwca 60000, were thermally stable up to ca 285 deg.C above which a chain-unzipping process resulted in the formation of monomer as the major degradation product. Glass transition temperatures (Tg) were not observed for poly(monotaconate)s; for poly(hexanoyl diitaconate) Tg was ca -18 deg.C whereas poly(1H,1H,2H,2H-perfluorodecanoyl diitaconate) exhibited two glass transition temperatures, attributed respectively to the relaxation of the alkyl side chain (ca 5 deg.C) and the overall polymer transition (ca 35 deg.C). Poly(hexadecanoyl diitaconate) was the only dditaconate to exhibit a melting endotherm. Surface energy contributions were calculated using the surface tension component (Good-Girafalco-Fowkes) theory. Recently-advanced and recently-receded contact angle measurements were performed at 25.0 + or - 0.2 deg.C for drops of water, diiodomethane and ethylene glycol on the itaconates that could be formed into films. Both recently-advanced and recently-retarded contact angles demonstrated the time-dependency of the wetting behaviour for drops of water, attributed to the slow, stepwise absorption of water by the polymer. Contact angles for drops of diiodomethane and ethylene glycol remained constant over time. Poly(1H,1H,2H,2H-perfluorodecanoyl diitaconate), PI-2, possessed the most hydrophobic surface (initial recently-advanced water contact angle: ca 120 degrees), whereas the least hydrophobic material was poly(hexadecanoyl diitaconate), PH-2; initial recently-advanced contact angle: ca 96 deg. Poly(1H,1H,2H,2H-perfluorodecanoyl diitaconate), PI-2, exhibited the lowest surface energy (advanced ca 7 mJm-2; receded: mean 9.7 mJm-2), whereas poly(hexadecanoyl diitaconate), PH-2 had the highest (advanced: ca 31-37 mJ m-2; receded 39.7 mJm-2). Poly(dodecanoyl monoitaconate), PA-5/6 exhibited surface energies of ca 22 mJ m-2 (advanced) and ca 31 mJ m-2 (receded). The low surface energy of poly(1H,1H,2H,2H-perfluorodecanoyl diitaconate), PI-2 is attributed to both the high hydrophobicity of the surface and the presence of pendent fluorocarbon side chains, which prevent the interaction of diiodomethane molecules with the polymer backbone. The relatively high surface energy of poly(hecadecanoyl diitaconate), PI-2, is due to the lower contact angles measured for this material. Increases in the basic contribution over time and its larger value relative to corresponding acidic contributions are attributed to the uptake of water by the polymer; hydrogen bonding with oxygen atoms of the ester linking group may provide the driving force behind the observed phenomenon. Antifouling performances were evaluated in seawater exposure trials over two fouling seasons. The sequence of fouling events was similar in both seasons: initial settlement by barnacles and algae follwed by settlement of tunicates. In the 1995 exposure trial polymers prepared by solution chain-growth polymerisation as well as a selection of commercial materials were evaluated. All samples exhibited almost no resistance to marine fouling. Suggested contributory factors to their poor performance was their low average relative molecular mass (Mw <15000), a variability of sample coatings or the ineffectiveness of the samples against the inhibition/prevention of settlement/attachment by marine fouling organisms. In the 1996 trial, high average molecular mass poly(itaconate) films prepared by bulk chain-growth polymerisation reactions were exposed. Poly(dodecanoyl monoitaconate)(PA-6), poly(1H,1H,2H,2H-perfluorodecanoyl monoitaconate) (PE-6) and poly(hexadecanoyl diitaconate) (PH-2) exhibited slight resistance to marine fouling, with resistances for these materials after seven months of exposure, of 13%, 18% and 34% respectively (control surfaces had fouling resistances of -5%). Areas free from coverage by fouling organisms were observed on all samples. The overall low resistance of poly(itaconate) can most likely be attributed to the absorption of water by these polymer films.
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Nader, Athir. "Engineering Characteristics of Sensitive Marine Clays - Examples of Clays in Eastern Canada." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30670.
Full textAbstract:
Sensitive marine clay in Ottawa is a challenging soil for geotechnical engineers. This type of clay behaves differently than other soils in Canada or other parts of the world. They also have different engineering characteristic values in comparison to other clays. Cone penetration testing in sensitive marine clays is also different from that carried out in other soils. The misestimation of engineering characteristics from cone penetration testing can result. Temperature effects have been suspected as the reason for negative readings and erroneous estimations of engineering characteristics from cone penetration testing. Furthermore, the applicability of correlations between cone penetration test (CPT) results and engineering characteristics is ambiguous. Moreover, it is important that geotechnical engineers who need to work with these clays have background information on their engineering characteristics.
This thesis provides comprehensive information on the engineering characteristics and behaviour of sensitive marine clays in Ottawa. This information will give key information to geotechnical engineers who are working with these clays on their behaviour. For the purpose of this research, fifteen sites in the Ottawa area are taken into consideration. These sites included alternative technical data from cone and standard penetration tests, undisturbed samples, field vanes, and shear wave velocity measurements. Laboratory testing carried out for these sites has resulted in acquiring engineering parameters of the marine clay, such as preconsolidation pressure, overconsolidation ratio, compression and recompression indexes, secondary compression index, coefficient of consolidation, hydraulic conductivity, clay fraction, porewater chemistry, specific gravity, plasticity, moisture content, unit weight, void ratio, and porosity. This thesis also discusses other characteristics of sensitive marine clays in Ottawa, such as their activity, sensitivity, structure, interface shear behaviour, and origin and sedimentation.
Furthermore, for the purpose of increasing local experience with the use of cone and ball penetrometers in sensitive marine clays in Ottawa, three types of penetrometer tips are used in the Canadian Geotechnical Research Site No. 1 located in south-west Ottawa: 36 mm cone tip, and 40 mm and 113 mm ball tips. The differences in their response in sensitive marine clays will be discussed. The temperature effects on the penetrometer equipment are also studied. The differences in the effect of temperature on these tips are discussed. Correlations between the penetrometer results and engineering characteristics of Ottawa's clays are verified.
The applicability of correlations between the testing results and engineering characteristics of sensitive marine clays in Ottawa is also presented in this thesis. Two correlations from the Canadian Foundation Engineering Manual are examined. One of these correlations is between the N60 values from standard penetration testing and undrained shear strength. The other correlation is between the shear wave velocity measurement and site class. Temperature corrections are suggested and discussed for penetrometer equipment according to laboratory calibrations. The significance of the effects due to radical temperature changes in Canada and Ottawa is discussed.
Some of the main findings from this research are as follows.
• The Canadian Foundation Engineering Manual presents a correlation between standard penetration tests (SPTs) and the undrained shear strength of soils. This relationship may not be applicable to sensitive marine clays in Ottawa.
• Another correlation between the site class, shear wave velocity, and undrained shear strength is presented by this same manual which may not be applicable to sensitive marine clays in Ottawa.
• The rotation rate for field vane testing as recommended by ASTM D2573 is slow for sensitive marine clays in Ottawa.
• Correction factors applied to undrained shear strength from laboratory vane tests may not result in comparable values with the undrained shear strength obtained by using field vane tests.
• Loading schemes in consolidation or oedometer testing may affect the quality of the targeted results.
• Temperature corrections should be applied to penetrometer recordings to compensate for the drift in the results of these recordings due to temperature changes.
• The secondary compression index to compression index ratio presented in the literature may not be the value obtained from this research.
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Karami, Hamidreza. "Causality Analysis of Construction Delays and Value Engineering Protocols in Marine Projects." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/84946.
Full textAbstract:
The central argument of this study is that if delay causation themes are known, but they are not analyzed by project peculiarities, research outcomes are not likely to deliver clear impact. Thus, this study aims to examine delay causations and how they apply to marine projects, and whether they can be mitigated by specific value engineering (VE) processes.
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Hummel, Robert A. (Robert Andrew). "Infrastructure for large-scale tests in marine autonomy." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70436.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 141-147).
This thesis focuses on the development of infrastructure for research with large-scale autonomous marine vehicle fleets and the design of sampling trajectories for compressive sensing (CS). The newly developed infrastructure includes a bare-bones acoustic modem and two types of low-cost and scalable vehicles. One vehicle is a holonomic raft designed for station-keeping and precise maneuvering, and the other is a streamlined kayak for traveling longer distances. The acoustic modem, like the vehicles, is inexpensive and scalable, providing the capability of a large-scale, low-cost underwater acoustic network. With these vehicles and modems we utilize compressive sensing, a recently developed framework for sampling sparse signals that offers dramatic reductions in the number of samples required for high fidelity reconstruction of a field. Our novel CS sampling techniques introduce engineering constraints including movement and measurement costs to better apply CS to sampling with mobile agents. The vehicles and modems, along with compressive sensing, strengthen the movement towards large scale autonomy in the ocean environment.
by Robert Andrew Hummel.
S.M.
33
Agosto, Priscilla (Priscilla M. ). "Fabrication of an 1897 Herreshoff marine steam engine." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112564.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 46-47).
A 19th century Herreshoff marine steam engine was developed using a combination of traditional and modern fabrication methods. Background on Nathaniel Herreshoff, his connection to MIT and the Herreshoff Manufacturing Company was provided. The process for selection of appropriate steam engine with the input from the Francis Russell Hart Nautical Museum at MIT was explored. CAD models were developed from the original drawings from MIT's Haffenreffer-Herreshoff Collection. Pattern making options, casting, sand types and machining practices were explored and analyzed. Furthermore, a blueprint for a single-semester course in advanced fabrication methods for MIT 2.007 Senior Undergraduate Apprentices was proposed.
by Priscilla Agosto.
S.B.
34
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.
Full textAbstract:
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.
35
Andrews, Gordon Moseley P. "Modeling and fabrication of an Atlantic marine engine." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112566.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (page 44).
Three-dimensional CAD models for the one-lunger Atlantic marine engine cylinder and manifold were developed from original engineering drawings, and the corresponding patterns and core molds for casting designed. The viability of CNC milled high-density foam for fabricating complex casting patterns and molds was demonstrated with the Atlantic engine cylinder and manifold. The modeling processes presented in this paper can be applied to other projects in documenting historical components and machinery, and the CNC fabrication techniques can be applied generally for rapid pattern and mold generation. From a historical perspective, the development of the models, patterns and physical castings presented in this paper are one step in restoring the heritage of the one-lunger marine engines and bringing life to the first Atlantic engine of the 2 1st century.
by Gordon Moseley P. Andrews.
S.B.
36
Qi, Yusheng Ph D. Massachusetts Institute of Technology. "Sea surface wave reconstruction from marine radar images." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74939.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 103-105).
The X-band marine radar is one type of remote sensing technology which is being increasingly used to measure sea surface waves nowadays. In this thesis, how to reconstruct sea surface wave elevation maps from X-band marine radar images and do wave field prediction over short term in real time are discussed. The key idea of reconstruction is using dispersion relation based on the linear wave theory to separate the wave-related signal from non-wave signal in radar images. The reconstruction process involves three-dimensional Fourier analysis and some radar imaging mechanism. In this thesis, an improved shadowing simulation model combined with wave field simulation models for the study of the correction function in the reconstruction process and an improved wave scale estimation model using non-coherent radar data are proposed, which are of great importance in the reconstruction process. A radar image calibration method based on wave field simulation is put forward in order to improve the quality of reconstructed sea surface wave. Besides, a theoretical wave scale estimation model using Doppler spectra of the coherent radar is put forward, which is proposed to be a good alternative to the current wave scale estimation model. The reconstructed sea surface wave can be used for wave field simulation in order to predict the wave field, which is not only an application of this reconstruction process, but also a parameter optimizing tool for the reconstruction process.
by Yusheng Qi.
S.M.
37
Cortes, Romero Juan Jose. "Reliability based design of marine risers." Thesis, University of Newcastle Upon Tyne, 1999. http://hdl.handle.net/10443/774.
Full textAbstract:
The harsh environment in which offshore structures must operate, their intended service life and the uncertainties inherent to the load processes, have been the impulse for investigation of their reliability. The method most extensively applied for this purpose during the last two decades was the Structural Systems Reliability, which can not be coupled with the finite element method. Therefore the objectives of the present work are to investigate the applicability of a technique which allows the utilization of the reliability analysis methods with a marine riser modelled by the finite element method, FEM, and revision of the reliability levels associated with this riser, including the fatigue life. For these purposes the response surface methodology was selected, among a number of methods. A response surface approach which requires a low number of experiments with the FEM model was elected, calculations for construction of the response surface are further simplified by the assumption of statistical independence among the basic variables. It is demonstrated in the present study that the response surface is capable of producing an equivalent and explicit limit state function which is used at a second stage with the First Order Reliability Method and the Adaptive Importance Sampling simulation technique. However, it was found that the assumption of independence is not always valid. In this case, a method is proposed in which the correlated variables are implicitly considered at the level of the mechanical model. The reliability of the marine riser was reviewed with the proposed algorithms, finding that the validity of the reliability levels depend on the number of basic variables considered and their statistical properties. The significant reduction in required computing time achieved with the response surface methodology allowed parametric studies to be carried out, in order to investigate the impact of different statistical properties of the basic variables. The fatigue reliability case was also investigated with the S-N approach. The introduction of uncertainty in the fatigue life estimation proved that acceptable levels of deterministic fatigue life may render unacceptablelevels of reliability. The uncertainty associated with the stress range is the most significant variable, though the present fatigue reliability formats consider it in a very simplified manner, therefore an approach is suggested with which the stress uncertainty can be considered in a more detailed fashion. However, the algorithm used here for construction of the response surface was unable to produce the required surface. Therefore it is concluded that though the response surface is capable of handling a large number of structural reliability cases, there are instances in which more research efforts are needed.
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Bates, C. R. "Seismic anisotropy as an indicator of marine sediment stability." Thesis, Bangor University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236517.
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Gin, Karina Y. H. (Karina Yew Hoong). "Microbal size spectra from diverse marine ecosystems." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40155.
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Yee, Donald. "Cobalt substitution for zinc in marine phytoplankton." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43289.
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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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Ljungberg, Fredrik. "Estimation of Nonlinear Greybox Models for Marine Applications." Licentiate thesis, Linköpings universitet, Reglerteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-165828.
Full textAbstract:
As marine vessels are becoming increasingly autonomous, having accurate simulation models available is turning into an absolute necessity. This holds both for facilitation of development and for achieving satisfactory model-based control. When accurate ship models are sought, it is necessary to account for nonlinear hydrodynamic effects and to deal with environmental disturbances in a correct way. In this thesis, parameter estimators for nonlinear regression models where the regressors are second-order modulus functions are analyzed. This model class is referred to as second-order modulus models and is often used for greybox identification of marine vessels. The primary focus in the thesis is to find consistent estimators and for this an instrumental variable (IV) method is used. First, it is demonstrated that the accuracy of an IV estimator can be improved by conducting experiments where the input signal has a static offset of sufficient amplitude and the instruments are forced to have zero mean. This two-step procedure is shown to give consistent estimators for second-order modulus models in cases where an off-the-shelf applied IV method does not, in particular when measurement uncertainty is taken into account. Moreover, it is shown that the possibility of obtaining consistent parameter estimators for models of this type depends on how process disturbances enter the system and on the amount of prior knowledge about the disturbances’ probability distributions that is available. In cases where the first-order moments are known, the aforementioned approach gives consistent estimators even when disturbances enter the system before the nonlinearity. In order to obtain consistent estimators in cases where the first-order moments are unknown, a framework for estimating the first and second-order moments alongside the model parameters is suggested. The idea is to describe the environmental disturbances as stationary stochastic processes in an inertial frame and to utilize the fact that their effect on a vessel depends on the vessel’s attitude. It is consequently possible to infer information about the environmental disturbances by over time measuring the orientation of a vessel they are affecting. Furthermore, in cases where the process disturbances are of more general character it is shown that supplementary disturbance measurements can be used for achieving consistency. Different scenarios where consistency can be achieved for instrumental variable estimators of second-order modulus models are demonstrated, both in theory and by simulation examples. Finally, estimation results obtained using data from a full-scale marine vessel are presented.I takt med att marina farkoster blir mer autonoma ökar behovet av noggranna matematiska farkostmodeller. Modellerna behövs både för att förenkla utvecklingen av nya farkoster och för att kunna styra farkosterna autonomt med önskad precision. För att erhålla allmängiltiga modeller behöver olinjära hydrodynamiska effekter samt systemstörningar, främst orsakade av vind- och vattenströmmar, tas i beaktning. I det här arbetet undersöks metoder för att skatta okända storheter i modeller för marina farkoster givet observerad data. Undersökningen gäller en speciell typ av olinjära modeller som ofta används för att beskriva marina farkoster. Huvudfokus i arbetet är att erhålla konsistens, vilket betyder att de skattade storheterna ska anta rätt värden när mängden observerad data ökar. För det används en redan etablerad statistisk metod som baseras på instrumentvariabler. Det visas först att noggrannheten i modellskattningsmetoden kan förbättras om datainsamlingsexperimenten utförs på ett sätt så att farkosten har signifikant nollskild hastighet och instrumentvariablernas medelvärde dras bort. Den här tvåstegslösningen påvisas vara fördelaktig vid skattning av parametrar i den ovan nämnda modelltypen, framför allt då mätosäkerhet tas i beaktning. Vidare så visas det att möjligheten att erhålla konsistenta skattningsmetoder beror på hur mycket kännedom om systemstörningarna som finns tillgänglig på förhand. I fallet då de huvudsakliga hastigheterna på vind- och vattenströmmar är kända, räcker den tidigare nämnda tvåstegsmetoden bra. För att även kunna hantera det mer generella fallet föreslås en metod för att skatta de huvudsakliga hastigheterna och de okända modellparametrarna parallellt. Denna idé baserar sig på att beskriva störningarna som stationära i ett globalt koordinatsystem och att anta att deras effekt på en farkost beror på hur farkosten är orienterad. Genom att över tid mäta och samla in data som beskriver en farkosts kurs, kan man således dra slutsatser om de störningar som farkosten påverkas av. Utöver detta visas det att utnyttjande av vindmätningar kan ge konsistens i fallet med störningar av mer generell karaktär. Olika scenarion där konsistens kan uppnås visas både i teori och med simuleringsexempel. Slutligen visas också modellskattningsresultat som erhållits med data insamlad från ett fullskaligt fartyg.
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Nagarajan, Nishatha. "Target Tracking Via Marine Radar." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1345125374.
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Carkett, Rachel Amanda Jane. "Barriers to creativity in the conceptual phase of engineering design : perceptions of designers at Rolls Royce Aerospace (Bristol) in new projects engineering." Thesis, University of Plymouth, 2002. http://hdl.handle.net/10026.1/2661.
Full textAbstract:
Anecdotal evidence from experienced engineers suggest that barriers to creativity are often due to the limitations of current technology, methods and support systems (Baird, Moore, & Jagodzinski, 2000). The aim of this research was to explore what the perceived barriers to creativity are and how they are circumvented by design engineers working in New Projects Engineering (NPE), Rolls-Royce Aerospace (Bristol). Semi-structured interviews with four employees working in engineering design comprised a Scoping Study. This provided a general overview of the major issues perceived by the design engineers regarding barriers to creativity and resulted in six themes being identified. These themes were used as a framework for a Design Group Interviews Study that followed. Sixteen engineers comprising project managers, team leaders, experienced designers and new designers, graduate employees and trainees were interviewed using the same method. Using grounded theory to analyse the data, sixteen categories were drawn from the data. Confirmation of the findings was achieved through presentations and workshops with different groups from Rolls-Royce, and the development of an Interrelationship Digraph illustrating the relationships between the categories. The second phase of the research focused on the phenomena under current working conditions. In the Tracking Study interview diaries recorded with thirteen design engineers over an eight week period highlighted the salient issues relating to their perceived barriers to creativity. Thirteen categories (some of which could be mapped onto the previous categories and some which were new) were drawn from the data. Validation of the categories was achieved through direct observations of two design engineers in the week long Shadowing Study and completed this phase of the research. Mapping and interpretation of the findings in relation to the literature obtained further verification. From these analyses it was becoming evident that perceived barriers to creativity were present at iii many different layers of the enterprise from a macro, organisational level to the microenvironment of the individual design engineer. The final phase entailed the development of a conditional/consequential matrix model to illustrate the relationship between the macro and micro conditions, under which barriers to creativity were investigated, leading to the development of a theory. The final conclusions and suggestions for improvements demonstrate the relationship between high/low barriers and high/low creativity. The research has shown the benefits of taking an interdisciplinary socio-technical approach and has highlighted the importance and relevance of the social dimension, as well as the technological, in the investigation of engineering design. iv
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Taha, Ahmed M. "Interface Shear Behavior of Sensitive Marine Clays --Leda Clay." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28768.
Full textAbstract:
Leda clay, which is a type of sensitive marine clay in Canada, is a hazardous soil that could undergo sudden collapse and flow upon wetting and remolding. This type of soil causes many landslide disasters and foundation damage. The existence of Leda clay at or near the proximities of developed cities makes it challenging for infrastructure expansion, and therefore, challenging for geotechnical engineers. At the location where this sensitive marine clay exists, many foundation designers have adopted the use of deep foundations, such as pile foundations to support heavy structures. The shear behavior and strength parameters at the interface between the (friction) pile and soil are key design parameters. A sufficient knowledge of these interface shear behaviors and strength parameters is also essential for the safe and cost-effective design of several other geotechnical structures (e.g., retaining walls, reinforced soils, and buried structures). However, no studies have yet been implemented on the interface shear behavior between Leda clay and structural material. There is therefore, a need to generate more knowledge about the interface shear behavior of Leda clay.
This thesis deals with an experimental study of the shear behavior at the interface between Leda clay and structural material, such as steel and concrete. The effects of several factors, such as surface roughness of the construction material, Leda clay's overconsolidation ratio (OCR), saturation degree, density, and salt content on interface shear behavior are also investigated. Laboratory tests have been carried out by using an automatic direct shear machine connected to a linear variable differential transformer (LVDT), loading cell and a data logging system. The results of the interface shear tests show that under consolidated drained (CD) and saturated conditions, the interface friction angle increases with an increase in the clay's OCR. The results also indicate that increasing the salinity of Leda clay's pore water enhances its frictional resistance at the interface. Furthermore, the results reveal that Leda clay with a higher dry density shows higher interface shear resistance. On the other hand, the results also show that the interface shear resistance decreases as the degree of saturation of the Leda clay increases.
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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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Gerlach, Jacob. "Autonomous data collection techniques for approximating marine vehicle kinematics." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100132.
Full textAbstract:
Thesis: S.M. in Naval Architecture and Marine Engineering, and S.M. in Ocean Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 75-77).
Understanding vehicle kinematics is essential in allowing autonomous guidance algorithms to accurately assess short range encounters. Low cost, reconfigurable autonomous vehicles motivate using in-field online techniques rather than tow tank testing or Computational Fluid Dynamics (CFD). While the parameters of many physical dynamic models can be obtained using System Identification (SI) techniques, these models require knowledge of the vehicle actuators, which may not be the case in a "backseat driver" architecture using payload autonomy. Even when an identified physical model is available, using it to simulate trajectories requires insight into the design of the relevant controller, which may be proprietary or otherwise unknown to the back seat. This thesis develops a data collection procedure to obtain empirical kinematic trajectories for unmanned surface vehicles (USVs). A linear black box model of the USV yaw system is also developed, using only data available in the backseat. A prediction table for the M200 USV is developed with both techniques.
by Jacob Gerlach.
S.M. in Naval Architecture and Marine Engineering, and S.M. in Ocean Engineering
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Clarke, Sean Aidan. "Hypermutation and adaptation of experimentally evolved marine Vibrio bacteria." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81665.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 73-83).
Environmental bacteria display tremendous genetic diversity, but we are still learning how this diversity arises and relates to their wide range of habitats. Investigating how bacteria adapt helps us understand their contributions to environmental processes and informs forward engineering of bacteria for industrial applications. Experimental evolution is a powerful approach, with microbes especially, but it has mostly been applied to model organisms and metabolic functions. In the work here, we investigated the possibility, degree, and variability of adaptation of an environmental Vibrio strain by applying a little-used selection method appropriate to a relevant condition, salinity. We successfully isolated mutants with higher salt tolerance by selecting on salt gradient plates. Resequencing the genomes of the evolved strains revealed unprecedented hypermutation in three of nine parallel lineages. These mutator lines arose independently, and each of them accumulated more than 1500 single-base mutations. By comparison, there are only 302 single-base differences between the ancestor strain and another strain isolated in the wild. Hypermutation was associated with a deletion resulting from improper prophage excision. Members of this family of prophages are found in other proteobacteria, including well-studied human pathogens, from very different environments. Mutators are known to arise spontaneously in wild and clinical bacteria, but the extent of their adaptive contribution is unknown. We have preliminary evidence that this mechanism of evolution could be relevant in the environment, where horizontal gene transfer and mobile elements play known, significant roles in bacterial evolution.
by Sean Aidan Clarke.
Ph.D.
49
Fouquette, Jordan William. "Multipath arrival tracking for marine vehicles utilizing pattern recognition." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118663.
Full textAbstract:
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 123-124).
In recent years, interest in the Arctic Region has been steadily growing as it has become more accessible due to continued ice recession. This increased accessibility opens up the possibility for nations to take advantage of the region's abundant resources and trade routes thereby increasing military, political, and commercial interest. The extreme temperatures and significant ice cover in this region have created a unique and challenging acoustic environment. At increased distances, individual acoustic ray path data becomes inconsistent due to improper ray path identification and fading. Marine vehicles have the ability to overcome these challenges and increase contact tracking capabilities by taking advantage of the patterns associated with these multipath arrivals. Through the use of pattern recognition, a multipath arrival tracking algorithm was developed to utilize the unique characteristics associated with each individual ray path for long range tracking purposes. This tracking algorithm analyzes the amplitude and arrival time patterns amongst all individual ray paths in order to accurately identify each ray path as scattering and fading occurs, thereby increasing range-tracking capabilities. This becomes especially useful in the Arctic Region as contacts of interest can be tracked regardless of their position above, below, or within the Beaufort Duct- a newly discovered sound duct from 100 to 200 meters depth. Simulations covering the numerous depth combinations of sources and receivers with respect to the Beaufort Duct illustrate the difficulty in contact tracking within this harsh environment and highlight the effectiveness that is presented by utilizing multipath arrival data. The developed algorithm takes advantage of these unique patterns in order to provide a unique tracking capability for marine vehicles to employ.
by Jordan William Fouquette.
Nav. E.
S.M.
50
Mackechnie, James Ronald. "Predictions of reinforced concrete durability in the marine environment." Doctoral thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/21728.
Full textAbstract:
This thesis presents an investigation where an empirical method is proposed for predicting the durability of reinforced concrete structures in the marine environment. The objective was to identify reliable means of characterizing early-age properties of concrete which affect durability and relate these to the durability performance of the material under marine conditions. Establishing a relationship between early-age testing and long-term performance of concrete is a necessary precursor to implementing a system of performance-based durability specifications.