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1
Muralidharan, Shylesh. „Assessment of ocean thermal energy conversion“. Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76927.
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Thesis (S.M. in Engineering and Management)--Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 103-109).
Ocean thermal energy conversion (OTEC) is a promising renewable energy technology to generate electricity and has other applications such as production of freshwater, seawater air-conditioning, marine culture and chilled-soil agriculture. Previous studies on the technology have focused on promoting it to generate electricity and produce energy-intensive products such as ammonia and hydrogen. Though the technology has been understood in the past couple of decades through academic studies and limited demonstration projects, the uncertainty around the financial viability of a large-scale plant and the lack of an operational demonstration project have delayed large investments in the technology. This study brings together a broad overview of the technology, market locations, technical and economic assessment of the technology, environmental impact of the technology and a comparison of the levelized costs of energy of this technology with competing ones. It also provides an analysis and discussion on application of this technology in water scarce regions of the world, emphasized with a case study of the economic feasibility of this technology for the Bahamas. It was found that current technology exists to build OTEC plants except for some components such as the cold water pipe which presents an engineering challenge when scaled for large-scale power output. The technology is capital intensive and unviable at small scale of power output but can become viable when approached as a sustainable integrated solution to co-generate electricity and freshwater, especially for island nations in the OTEC resource zones with supply constraints on both these commodities. To succeed, this technology requires the support of appropriate government regulation and innovative financing models to mitigate risks associated with the huge upfront investment costs. If the viability of this technology can be improved by integrating the production of by-products, OTEC can be an important means of producing more electricity, freshwater and food for the planet's increasing population.
by Shylesh Muralidharan.
S.M.in Engineering and Management
2
Lin, Steve S. (Steve Simpson) 1976. „A distributed interactive ocean visualization system“. Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80102.
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Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (leaf 47).
by Steve S. Lin.
S.B.and M.Eng.
3
Amy, John Victor. „Composite system stability methods applied to advanced shipboard electric power systems“. Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/10945/23576.
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CIVINSLarge increases in the complexity of shipboard electric loads as well as development of electric drive, integrated electric drive and pulsed power systems make manifest the present and future importance of naval electric power systems. The most crucial attribute of these systems is their ability to fulfill their function in the presence of "large-signal" perturbations. Fundamental differences between shipboard and commercial electric power systems make all but the most general nonlinear, "large-signal" stability analyses inappropriate for the design and assessment of naval electric power systems. The tightly coupled and compact nature of shipboard systems are best accommodated by composite system stability analyses. Composite system methods, based upon Lyapunov's direct method, require that each component's stability be represented by a Lyapunov function. A new Lyapunov function which is based upon coenergy is developed for 3-phase synchronous machines. This use of coenergy is generalizable to all electromechanical energy conversion devices. The coenergy-based Lyapunov function is implemented as a "stability organ" which generates waveforms at information teirninals of a "device object" in the object oriented simulation environment of WAVESIM. Single generator simulation results are used to acquire a measure of the "over sufficiency" of the coenergy-based Lyapunov function. Some means of combining the components' Lyapunov functions is necessary with composite system stability criterions. To provide the largest stability region in a Lyapunov function convective derivative space, thereby reducing "over sufficiency", a "timevariant weighted-sum" composite system criterion is developed. This criterion is implemented as a "stability demon" "device object" within the WAVESIM environment. The "stability demon" is tested through RLC circuit simulations and a two-generator simulation. The output of the "stability demon" is suitable for use within an overall system stabilising controller.
4
Sarkar, Apurva Kumar. „polarized radiative transfer in atmosphere ocean system“. Thesis, University of North Bengal, 2014. http://hdl.handle.net/123456789/1578.
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5
Cooper, Kyle Francis. „Evaluating global ocean reanalysis systems for the greater Agulhas Current System“. Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/12829.
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Includes bibliographical references.Operational oceanography aims to accurately hindcast and forecast the state of the ocean. An international initiative, the Global Ocean Data Assimilation Experiment (GODAE), developed and increased the capacity for global operational oceanography. However, the products from the global initiatives were regionally inapplicable due to low spatial resolutions, and have recently improved through GODAE OceanView. A number of local operational oceanographic initiatives have been setup over the southern African regional ocean, but proved to be unsustainable and ended. Recently, the aim to develop a regional ocean prediction system has arisen, and initial steps have been taken. This thesis aims to address the lack of local capacity in operational oceanography, and contribute to a crucial process in developing a regional ocean prediction system. Here, we validate and investigate the differences between three global reanalysis products, namely MyOcean (GLORYS2V1), HYCOM (U.S Naval Research Laboratory) and BlueLINK (OFAM3). These reanalysis products are validated and investigated over the greater Agulhas Current System, which is a crucial system in Southern African regional ocean. The salient oceanographic features represented in the reanalysis products are initially compared to historical literature of the region and followed by available unassimilated observations (i.e. independent). The results show that the reanalysis products from MyOcean, and the U.S Naval Research Laboratory satisfactorily simulate the major salient oceanographic features of the Agulhas Current System. Bluelink does not correctly portray the structure of the source and retroflection regions, and therefore has limited use over the Agulhas Current System. The differences between the three products indicates that the data assimilate does not sufficiently constrain the models in order for their solutions over the Agulhas System to converge. The evaluation of these global ocean reanalysis products is a critical step toward a regional ocean prediction system over Southern Africa, and building toward the local capacity to accomplish this goal.
6
Pedroza, Moises. „MOBILE TRACKING SYSTEM “MOTION ON THE OCEAN” TEST“. International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608307.
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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, NevadaThe Transportable Range Augmentation and Control System (TRACS), Mobile Telemetry System (MTS), is a versatile system capable of supporting anywhere when called upon. The MTS is designed to operate anywhere on land. It is unknown how the system will perform on a floating platform without a stabilizing gimbal. The operation of a tracking system at sea generally require the use of a three-axis pedestal. The MTS is a two-axis pedestal. This paper is a report on how the MTS responds to simulated ocean-motion. Testing the system on a body of water is very expensive, especially out in the desert. The MTS was tested in the desert area of Las Cruces, New Mexico in the parking lot of EMI Technologies, prime contractor, using two forklifts to simulate ship motion in the pitch and yaw planes. The location is perfect for crossover dynamics tests. The tests conducted were for the purpose of determining if the MTS could auto-track a moving signal in space while it also moves due to “simulated ocean swells” that increase the generated tracking error signal levels in an opposite or in addition to the ones generated from the space vehicle. There is no gyroscopic correction. Successful results of the tests could preclude the use of a gyroscopically stabilized gimbaled platform necessary to keep the tracking system steady for auto-tracking a target during “6 degrees of freedom” disturbances. Several thousand dollars can be saved if the concept can be proven.
7
Braga, Martim Mas e. „Frontal system changes in the Southeastern Atlantic Ocean“. Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/21/21135/tde-09042018-112125/.
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The transition between the South Atlantic and the Southern Ocean is marked by a frontal system that includes both the South Atlantic Current and the Antarctic Circumpolar Current (ACC). In the eastern part of the basin the latitudinal position of the fronts that compose this system is thought to control the input of warm waters into the Atlantic basin through the Agulhas Leakage. Changes in the Subtropical and Polar regimes associated with the system that marks the boundary between the Subtropical Gyre and the ACC are investigated using the simulation results of the ocean component of the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM), POP2. Sea surface height gradients and specific contours are used to identify and track the ocean fronts position. We compare the Subtropical Front position at the eastern edge of the South Atlantic to changes in temperature and salinity, as well as Agulhas Current transports and the overlying wind field, in order to determine what could be driving frontal variability at this region and its consequences to volume transport from the Indian into the Atlantic. Results suggest that the Subtropical Front is not the southern boundary of the subtropical gyre, but it responds to changes in the \"Supergyre\", especially the Indian Ocean Subtropical Gyre expansion.A transição entre os oceanos Atlântico Sul e Austral é marcada por um sistema frontal que inclui tanto a Corrente do Atlântico Sul quanto a Corrente Circumpolar Antártica (CCA). Na porção oeste da bacia, acredita-se que a posição meridional das frentes que compõem este sistema controla o aporte de águas quentes para o Atlântico pelo Vazamento das Agulhas. Mudanças nos regimes subtropical e polar associadas ao sistema que marca o limite entre o giro subtropical e a CCA são investigadas através dos resultados da componente oceânica do modelo do National Center for Atmospheric Research (NCAR), o Community Earth System Model (CESM). O gradiente meridional, bem como valores específicos de altura da superfície do mar são usados para identificar e acompanhar a posição destas frentes oceânicas. A comparação da posição da Frente Subtropical no limite leste do Atlântico Sul com as mudanças na temperatura e salinidade, assim como no transporte da Corrente das Agulhas e do campo de ventos sobrejacente, é feita para determinar quais as forçantes da variabilidade frontal nesta região e suas consequências no transporte de volume entre o Índico e o Atlântico. Resultados sugerem que a Frente Subtropical não é o limite sul do giro subtropical, mas responde às mudanças no \"Supergiro\", especialmente à expansão do Giro Subtropical do Oceano Índico.
8
Loveday, Benjamin. „Modelling wind-driven inter-ocean exchange in the greater Agulhas with the regional ocean modelling system“. Doctoral thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/8805.
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Includes bibliographical references.Two Regional Ocean Modelling System configurations, AGIO and ARC112, are developed to investigate (1) the structure of the Agulhas leakage, (2) the dynamical link between the leakage and the Agulhas Current, and (3) the sensitivity of this link to changes in the regional wind field. Both configurations span the Indian Ocean and South East Atlantic Ocean (29° W - 115° E, 48.25° S - 7.5° N) at 1/4° resolution. ARC112 includes a two-way, AGRIF nested, 1/12° child domain, encapsulating the Agulhas retroflection (0° E - 40° E, 45.5° S - 29.5° S). Model evaluation shows that the basin-scale circulation patterns of the South Indian Ocean are appropriately captured. Western boundary transports match those derived from in situ hydrography, though source region fluxes exceed those observed. Both configurations exhibit inertially governed retroflections and produce Agulhas rings with eddy kinetic energy patterns consistent with those derived from altimetry. Improved topography in ARC112 yields a retroflection position and leakage value closer to observations. Dominant regional water masses are captured, but discrepancies in their distributions remain, especially in highly turbulent areas. The interannual variability of upper ocean heat content is well captured, and Indian Ocean dipole modes are appropriately expressed. Leakage is shown to be confined to the top 1500 m. Flux estimates, derived using complementary Eulerian passive tracer and Lagrangian virtual float techniques, converge where retroflection position is more accurate. Eddy flux, isolated using an Okubo-Weiss parameterisation, contributes only 1/3 to the total flux at the GoodHope line, with a 2:1 anticyclone to cyclone ratio. The remaining intra-ring flux occurs due to mixing between rings in the Cape Basin thermocline, which contains up to 50% Indian Ocean waters. Using a hybrid-criteria eddy-tracking scheme, ARC112i is shown to represent all three recently identified eddy paths, producing an accurate number of rings and cyclones with trajectories and radii that mirror observations, despite higher simulated speeds. A multi-decadal strengthening of the eddy component of Agulhas leakage is ascribed to increases in anti-cyclone speed and cyclone size. Linear changes in trade wind intensity, imposed through a series of idealised wind stress anomalies, concomitantly modulate Agulhas Current transport. The leakage flux response to changing western boundary current inertia is minimal, decreasing with higher resolution. Large changes in eddy kinetic energy are associated with small leakage anomalies, suggesting that the former is a poor leakage proxy. Initially, the leakage responds linearly to increasing westerly wind intensity, but increased mixing between the Agulhas Return Current and Antarctic Circumpolar Current reduces inter-basin flux as the latter adjusts. Consequently, it is suggested that Agulhas Current and leakage magnitude may, to a degree, vary independently, and that multi-decadal trends in the region may be a function of the wind forcing used. Equatorward shifts in the zero line of wind-stress curl drive a small leakage increase, counter to proposed palaeoceanographic mechanism where leakage is implied to reduce under these conditions.
9
Lai, Sherman. „Shared displays to support collaborative exploration of ocean summits“. Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/711.
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In group decision support systems, understanding the roles, dynamics and relationships between participants is imperative to streamlining the decision-making process. This is especially true when decision makers have varying interests. Research has shown that decision-making processes amongst groups with varying interests will often reach bottlenecks with issues, such as unwillingness to share information, or a limited ability of the participants to share ideas at the same time. We explored this research territory of group decision-making by implementing collaboration software to support Ocean Summits, a new approach that uses real-time simulations as part of the decision-making process for stakeholders to explore fisheries management policies. The research reported in this thesis has three goals: (1) to better understand the decision-making process in fisheries management, (2) to build a prototype system to tackle the major issues in the decision-making process and (3) to determine the best way to share and display information critical to the stakeholders' decision-making process by exploring the use of shared screens and information in comparison to private displays. We discovered that the use of shared screens with shared information yielded the best results, as opposed to private screens with shared information or private screens with private information. It was observed that sharing information allowed participants to explore more alternative solutions.
10
Deucker, Stefan. „An efficient propulsion system for small underwater vehicles“. Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/44486.
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11
Farneti, Riccardo. „Oceanic planetary waves in the coupled ocean-atmosphere system“. Thesis, University of Southampton, 2005. https://eprints.soton.ac.uk/25139/.
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The propagation of planetary, or Rossby, waves is studied under the effects of different atmospheric couplings. First, analytical matchings are formulated in which a Rossby wave is coupled to different thermodynamical atmospheres, from a simple heat flux condition to the inclusion of an atmospheric energy balance model. The effects on the vertical structure and phase speed of the first modes are negligible. However, it is shown that for the latter case an unstable mode appears. This growing mode, of decadal period and growth rate, has no physical source of energy and therefore is a result of the oversimplified atmosphere employed. In fact, adding physics to the atmospheric model results in a gradual disappearance of the instability. The possibility of observing similar unphysical modes in climate studies, where oversimplified models are adopted, is raised. Next, a quasi-geostrophic coupled model is used in order to analyse the oceanic Rossby wave characteristics under the influence of a full atmosphere. The idealised eddy-resolving model consists of an ocean basin underneath a channel atmosphere, and different configurations for the oceanic component are used. The Rossby waves are observed to propagate faster than both the classical linear theory (unperturbed solution) and the phase speed estimates when the effect of the zonal mean flow is added (perturbed solution). Moreover, using statistical eigentechniques, a coupled Rossby wave is identified, bearing the characteristics of the coupled mode proposed by Goodman and Marshall (1999). It is argued that the atmospheric coupling is capable of adding an extra speed up to the wave; in fact, when the waves are simply forced, their propagation speed approaches the perturbed solution. The waves are observed to break into faster waves, as suggested by LaCasce and Pedlosky (2004), although their resistance to dissipation and instabilities processes is enhanced by the atmospheric coupling, which provides extra energy to the initial wave during its propagation. The development of a coupled Rossby wave is found to be possible in a basin of the dimensions of both the Pacific and the Atlantic ocean, and its characteristics and strength vary little when the tridimensional accuracy of the ocean is increased.
12
Whitcomb, Clifford Alan. „Composite system analysis of advanced shipboard electrical power distribution systems“. Thesis, Cambridge, Massachusetts : Massachusetts Institute of Technology, 1992. http://handle.dtic.mil/100.2/ADA254851.
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Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1992 and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1992.Thesis Advisor: Kirtley, James L., Jr. "May 1992." Description based on title screen as viewed on March 30, 2009. Includes bibliographical references (p. 73-74). Also available in print.
13
Mihanetzis, Konstantinos P. 1968. „Towards a distributed information system for costal zone management“. Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80193.
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Thesis (Nav.E. and S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1999.Includes bibliographical references (leaves 57-59).
by Konstantinos P. Mihanetzis.
Nav.E.and S.M.
14
Middaugh, Regina A. „A knowledge based expert system for analyzing welded structures“. Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36013.
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Catipovic, Josko A. „Design and performance analysis of a digital acoustic telemetry system“. Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14430.
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Bst, Neil A. (Neil Andrew). „Preliminary design of a recirculating aquaculture system in Boston Harbor“. Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10275.
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17
Meuleners, Michael Joseph. „A numerical study of the mesoscale eddy dynamics of the Leeuwin Current system“. University of Western Australia. School of Environmental Systems Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0134.
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[Truncated abstract] The study of eastern ocean boundary currents has been principally restricted to the Pacific and Atlantic ocean regions. The traditional view of the circulation near eastern ocean boundaries is that upwelling-favourable winds force surface waters offshore, leading to upwelling of cold, nutrient-rich subsurface water at the coast, the formation and offshore advection of a coastal front, and the generation of alongshore currents, generally having an equatorward surface flow and a poleward undercurrent. The eastern ocean boundary system of the southern Indian Ocean, off the west coast of Australia, is unique compared with these regions because a warm, poleward surface flow, known as the Leeuwin Current, dominates the dynamics over the continental shelf. Satellite imagery has shown the Leeuwin Current consists of a complex system of meanders, jet-like streams, and eddies, and has a seasonal and interannual variability. The oceanic circulation of the region between Carnarvon (latitude 25°S) and Jurien Bay (latitude 31°S) was examined using observational and remotely sensed data in conjunction with a detailed numerical modelling study. The model was validated using in situ ADCP and CTD data, and the horizontal eddy viscosity parameterization was tested against field observations. ... The resulting offshore meander grew laterally, shallowed, and closed to form an anticlockwise eddy to the original clockwise eddy’s south, forming a characteristic LC eddy pair (dipole). The model demonstrated the LC and Leeuwin Undercurrent (LUC) coupling played an important role in the onset of eddies at both sites. When an energy diagnostic scheme was used, the dominant instability process linked to the anticlockwise eddy’s development at site 1 was a mixed mode barotropic and baroclinic instability. The baroclinic instability’s source was the available potential energy stored within the mean lateral density gradient. The LC’s meandering southerly flow interacting with the LUC’s northerly subsurface flow generated the horizontal shear that sourced the barotropic instability. The dominant instability process at site 2 was baroclinic in origin. Possible links between the eddy field dynamics and the shelfslope region’s alongshore topographic variability were considered. The results of a suite of five model runs, differing only in the specification of bottom topography, were contrasted to investigate the effects. Except for the expected alongshore variability, delay in the onset of instabilities, varying growth rates, and some differences in the dominant wavebands’ mesoscale patterns, the overall impression was the response was similar.
18
Freides, Drew Scott. „An image processing based system for three dimensional sail shape analysis“. Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13424.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1991.Title as it appears in the June, 1991 M.I.T. Graduate List: An image processing based approach to 3-dimensional sail shape analysis.
Includes bibliographical references (leaf 63).
by Drew Scott Freides.
M.S.
19
Rahm, Magnus. „Ocean Wave Energy : Underwater Substation System for Wave Energy Converters“. Doctoral thesis, Uppsala universitet, Elektricitetslära, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-112915.
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This thesis deals with a system for operation of directly driven offshore wave energy converters. The work that has been carried out includes laboratory testing of a permanent magnet linear generator, wave energy converter mechanical design and offshore testing, and finally design, implementation, and offshore testing of an underwater collector substation. Long-term testing of a single point absorber, which was installed in March 2006, has been performed in real ocean waves in linear and in non-linear damping mode. The two different damping modes were realized by, first, a resistive load, and second, a rectifier with voltage smoothing capacitors and a resistive load in the DC-link. The loads are placed on land about 2 km east of the Lysekil wave energy research site, where the offshore experiments have been conducted. In the spring of 2009, another two wave energy converter prototypes were installed. Records of array operation were taken with two and three devices in the array. With two units, non-linear damping was used, and with three units, linear damping was employed. The point absorbers in the array are connected to the underwater substation, which is based on a 3 m3 pressure vessel standing on the seabed. In the substation, rectification of the frequency and amplitude modulated voltages from the linear generators is made. The DC voltage is smoothened by capacitors and inverted to 50 Hz electrical frequency, transformed and finally transmitted to the on-shore measuring station. Results show that the absorption is heavily dependent on the damping. It has also been shown that by increasing the damping, the standard deviation of electrical power can be reduced. The standard deviation of electrical power is reduced by array operation compared to single unit operation. Ongoing and future work include the construction and installation of a second underwater substation, which will connect the first substation and seven new WECs.
20
Beer, Christopher James. „Planktic foraminifera, ocean sediments and the palaeo-marine carbonate system“. Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/208361/.
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Pistoia, Jenny <1983>. „Development of SuperEnsemble Techniques for the Mediterranean Ocean Forecasting System“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4303/4/Pistoia_Jenny_tesi.pdf.
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This research activity studied how the uncertainties are concerned and interrelated through the multi-model approach, since it seems to be the bigger challenge of ocean and weather forecasting. Moreover, we tried to reduce model error throughout the superensemble approach. In order to provide this aim, we created different dataset and by means of proper algorithms we obtained the superensamble estimate. We studied the sensitivity of this algorithm in function of its characteristics parameters. Clearly, it is not possible to evaluate a reasonable estimation of the error neglecting the importance of the grid size of ocean model, for the large amount of all the sub grid-phenomena embedded in space discretizations that can be only roughly parametrized instead of an explicit evaluation. For this reason we also developed a high resolution model, in order to calculate for the first time the impact of grid resolution on model error.
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Pistoia, Jenny <1983>. „Development of SuperEnsemble Techniques for the Mediterranean Ocean Forecasting System“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4303/.
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This research activity studied how the uncertainties are concerned and interrelated through the multi-model approach, since it seems to be the bigger challenge of ocean and weather forecasting. Moreover, we tried to reduce model error throughout the superensemble approach. In order to provide this aim, we created different dataset and by means of proper algorithms we obtained the superensamble estimate. We studied the sensitivity of this algorithm in function of its characteristics parameters. Clearly, it is not possible to evaluate a reasonable estimation of the error neglecting the importance of the grid size of ocean model, for the large amount of all the sub grid-phenomena embedded in space discretizations that can be only roughly parametrized instead of an explicit evaluation. For this reason we also developed a high resolution model, in order to calculate for the first time the impact of grid resolution on model error.
23
Psallidas, Konstantinos 1973. „Forecasting the system-level impact of technology infusion on conventional submarine design“. Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/91799.
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Thesis (S.M. in Ocean Systems Management; and, Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2003.Includes bibliographical references (leaves 105-107).
by Konstantinos Psallidas.
S.M.in Ocean Systems Management; and, Nav.E.
24
Moore, William H. (William Henry). „Simulation modeling of a container landbridge system across the Isthmus of Tehauntepec, Mexico“. Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13979.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1990.Title as it appears in the M.I.T. Graduate List, Feb. 1990: Simulation modeling of container landbridge transportation system across the Isthmus of Tehauntepec, Mexico.
Includes bibliographical references (leaf 137).
by William H. Moore.
M.S.
25
Marquardt, J. Paul (Joseph Paul) 1975. „The use of foil generated vorticity as a hover actuator system for undersea vehicles“. Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50553.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1998.Includes bibliographical references (p. 88-89).
The hover actuator system is a proof of concept platform. The design models the ability of a flapping foil to assist an undersea vehicle's shallow water sea-keeping performance. Goals of this study are to demonstrate an effective regime of foil motion amplitude, frequency, pitch angle offset, pitch angle amplitude and phase angle for two types of motion. Using the time-averaged thrust coefficient, I find that the lower frequencies provide the highest thrust coefficient of 3.1 at G0=600, hdc= 1.5, and f=0.4Hz for the treading water mode. Significantly lower thrust coefficients are observed for the figure eight mode with maximum of 1.8 occurring at G0=300, hdc=1, and f-0.2Hz. In addition to finding the optimal regime of thrust coefficient, the total thrust is also analyzed to find the regimes of absolute maximum thrust. Again, for the water treading mode the peak thrust was 24Newtons at 00=600, hjc=2.5, and f=0.6Hz; and for the figure eight mode the peak thrust of 7.5Newtons occurs at 00=450, hdc=2.7, and f-0.2Hz. Finally, the rationale of using such an apparatus, arguments, and test results are discussed in conclusion.
by J. Paul Marquardt.
S.M.
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Fanning, Augustus F. „Studies of the ocean-atmosphere system using a coupled climate model“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ32744.pdf.
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Graham, Robert M. „The role of Southern Ocean fronts in the global climate system“. Doctoral thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-108736.
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The location of fronts has a direct influence on both the physical and biological processes in the Southern Ocean. However, until recently fronts have been poorly resolved by available data and climate models. In this thesis we utilise a combination of high resolution satellite data, model output and ARGO data to improve our basic understanding of fronts. A method is derived whereby fronts are identified as local maxima in sea surface height gradients. In this way fronts are defined locally as jets, rather than continuous-circumpolar water mass boundaries. A new climatology of Southern Ocean fronts is presented. This climatology reveals a new interpretation of the Subtropical Front. The currents associated with the Subtropical Front correspond to the western boundary current extensions from each basin, and we name these the Dynamical Subtropical Front. Previous studies have instead suggested that the Subtropical Front is a continuous feature across the Southern Ocean associated with the super gyre boundary. A comprehensive assessment of the relationship between front locations and wind stress is conducted. Firstly, the response of fronts to a southward shift in the westerly winds is tested using output from a 100 year climate change simulation on a high resolution coupled model. It is shown that there was no change in the location of fronts within the Antarctic Circumpolar Current as a result of a 1.3° southward shift in the westerly winds. Secondly, it is shown that the climatological position of the Subtropical Front is 5-10° north of the zero wind stress curl line, despite many studies assuming that the location of the Subtropical Front is determined by the zero wind stress curl. Finally, we show that the nutrient supply at ocean fronts is primarily due to horizontal advection and not upwelling. Nutrients from coastal regions are entrained into western boundary currents and advected into the Southern Ocean along the Dynamical Subtropical Front.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.
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Legge, Oliver. „The role of carbonate system dynamics in Southern Ocean CO2 uptake“. Thesis, University of East Anglia, 2017. https://ueaeprints.uea.ac.uk/66840/.
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Three years of carbonate system measurements from Ryder Bay on the West Antarctic Peninsula are presented. The strong, asymmetric seasonal cycle of surface water Dissolved Inorganic Carbon (DIC) is quantitatively attributed to four processes:mixing of water masses, air-sea CO2 flux, calcium carbonate precipitation/dissolution and photosynthesis/respiration. In summer, reduced mixing with deeper water, net photosynthesis, and melting glacial ice and sea ice reduce DIC. In winter, mixing with deeper water and net heterotrophy increase DIC, resulting in aragonite saturation states close to 1. Ryder Bay is a net annual sink of atmospheric CO2 of 0.90-1.39 mol C m-2 yr-1. The observed variability demonstrates that future climatic changes may significantly affect carbon cycling in this dynamic environment. Carbonate system measurements from the Drake Passage and A23 sections are compared. Lower Circumpolar Deep Water (LCDW) becomes colder and fresher from Drake Passage to A23 due to mixing in the Scotia Sea. The coincident decrease in Total Alkalinity (TA) increases the fugacity of CO2, potentially reducing CO2 uptake in the Weddell Sea through the influence of upwelling LCDW on surface waters. Ventilation of Upper Circumpolar Deep Water (UCDW) in the south of Drake Passage suggests that this region is an important source of CO2 to the atmosphere. The zonal variability of the carbonate system in deep water masses around the Antarctic Circumpolar Current is assessed. Zonal variability, caused by the inflow of North Atlantic Deep Water in the Atlantic sector and UCDW in the Indian and Pacific sectors, has implications for regional air-sea CO2 flux in the high-latitude Southern Ocean. Temporal variability in Sub-Antarctic ModeWater is investigated. Most of the observed DIC increase is attributed to rising atmospheric CO2. There is also weak evidence for increasing remineralised organic carbon, possibly relatedto changes in the strength and location of ventilation.
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Maas, Natasha. „Design of a flexible containment system for deep ocean oil spills“. Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84370.
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Thesis (S.M.)--Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 153-155).
BP needed almost 3 months to cap the Deepwater Horizon spill; improved response techniques are needed for the future. This work presents the design and deployment plan for a new type of containment system that captures the vast majority of hydrocarbons exiting the wellhead. The structure is lightweight, flexible and modular, using a passively induced chimney affect as its working principle. It is modular to create one design that fits any number and size of wells. Modularity comes from 100m sections of thin Kevlar fabric, forming a cylinder that starts several meters above the seabed and ends several meters below the sea surface. The system is stored onshore mostly assembled until needed. The 3m-diameter shroud induces a flow that dilutes the gas to avoid hydrate formation. Yet the velocity is sufficiently small for gas to dissolve, reducing surface gas concentrations below workers' safety thresholds. The chimney effect causes a pressure differential over the material; reinforcement ribs are required to keep the system from collapsing inward. At the shroud top, the jet enters a containment pen, which is loosely attached to the shroud allowing it to ride the waves in heave, but constraining roll, pitch and yaw. The pen diameter allows oil to separate from the water; a skimmer weir in the pen collects almost pure oil and pumps it to a tanker. An air can at the shroud top provides pre-tension that restrains lateral deflections due to a uniform current, and helps reduce the collapse due to the pressure differential. The deflection and collapse are calculated for a uniform current using catenary equations. The results are used to verify the applicability of OrcaFlex, software commonly used by the offshore industry, which is then used to confirm the systems ability to satisfy design requirements under realistic conditions (a sea spectrum and non-uniform current). The 'one design fits all' objective is tested by initially designing the system for a moderate size reference well, and then scaling it up (with minor modifications) to fit the Macondo well. The results confirm that one design of the system can contain spills of moderate size in addition to those similar to the Deepwater Horizon.
by Natasha Maas.
S.M.
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Gupta, Mukund. „Climate system response to perturbations : role of ocean and sea ice“. Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127142.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 169-187).
When the Earth experiences a perturbation in its radiative budget, the global ocean can buffer climate change, while sea ice may amplify its effects via a positive albedo feedback. It is therefore of interest to consider the role of the ocean in the climate's response to changes in external forcing, such as volcanic eruptions, Snowball Earth initiation and rearrangements of the carbon cycle. The first part of this thesis isolates the impact of the deep ocean in the surface response to volcanic cooling. Relaxation of the surface temperature follows a two-timescale decay, due to ocean heat exchange being significantly stronger than climatic feedbacks. Deep ocean cooling sequestration helps explain long periods of cold climate that occurred, for example, during the Little Ice Age. The second part explores the volcanic forcing required to initiate state transitions in a GCM with multiple climate equilibria. Snowball transitions require cooling on the order of -100Wm⁻² for several decades. These transition timescales are a consequence of the whole water column needing to be cooled to the freezing point before sea ice develops at the surface. The third part investigates biogeochemical interactions between oceans and sea ice around Antarctica. During the glacial cycles of the Pleistocene, sea ice may have helped trap carbon in the ocean by inhibiting CO₂ outgassing. This work shows that flux capping may be weakened by the effect of sea ice on reducing the light available for biological productivity. Consequently, a large sea ice fraction is required to effectively cap the flux of carbon to the atmosphere.
by Mukund Gupta.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences
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Williams, R. G. „The influence of air-sea interaction on ocean synoptic-scale eddies“. Thesis, University of East Anglia, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377713.
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Wariyapola, Pubudu C. (Pubudu Chaminda) 1972. „Towards an ontology and metadata structure for a distributed information system for coastal zone management“. Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80236.
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Ofoegbu, James Nwachukwu. „Fender system behavior in random seas“. [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3028.
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Matlakala, Mmakabele Lebogang. „Seasonal characteristics of phytoplankton bloom phenology in the northern Benguela Upwelling System“. Master's thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/31598.
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Seasonal phytoplankton blooms in the Benguela Upwelling System (BUS) play a crucial role in ecosystem services and driving climate change through air-sea gas exchanges. Upwelling systems are particularly are sensitive to effects of climate change including the transport of nutrients, which influence the composition of phytoplankton communities. This is important because species composition affects a number of key processes that have significant climate feedbacks. This study uses historical long-term in situ data (at 10 and 70 NM stations) as well as OC-CCI satellite ocean colour data to investigate seasonal phytoplankton bloom phenology and community structure of diatoms, dinoflagellates and coccolithophores in the northern BUS. The seasonal cycle of satellite chlorophyll was used to determine the timing of bloom initiation at inshore and offshore boxes that overlapped the in situ stations. An ocean colour algorithm to detect coccolithophore presence and absence was used to determine the inshore-offshore seasonal cycle of coccolithophores. Results indicate a gradual decrease in chlorophyll concentration further offshore as well as high intra-seasonal, inter-annual and spatial variability. Offshore blooms initiate later and last longer than inshore blooms which have a higher magnitude. Diatoms are dominant over dinoflagellates and coccolithophores throughout the northern BUS, with higher concentrations observed at the inshore station (10 NM) for all three phytoplankton groups. However, satellite results show a higher presence of coccolithophores in the offshore region during spring and summer that is associated with periods of strong stratification. This study provides a better understanding of the characteristics of the phytoplankton seasonal cycle in the northern BUS which is useful for detecting trends and possible change associated with climate change forcing in response to global warming.
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Kennedy, Richard A. „A numerical study of the forcing mechanisms of the Leeuwin current system /“. Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FKennedy.pdf.
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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2002.Thesis advisor(s): Mary L. Batteen, Curtis A. Collins. Includes bibliographical references (p. 93-96). Also available online.
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Mennitt, Stuart Hayden. „The effects of ship load variations and seastate on hull girder deflection and combat system alignment“. Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/32578.
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Meuleners, Michael Joseph. „A numerical study of the mesoscale eddy dynamics of the Leeuwin Current system /“. Connect to this title, 2005. http://theses.library.uwa.edu.au/adt-WU2007.0134.
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Martin, Richard James. „Multivariable control system design for a submarine using active roll control“. Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/10945/21456.
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Coxon, Peter John. „System identification of submarine hydrodynamic coefficients from simple full scale trials“. Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14129.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1989.Includes bibliographical references (leaves 110-112).
by Peter John Coxon.
M.S.
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Miller, Bryan D. (Bryan David). „Design of an AUV recharging system“. Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33561.
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Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 57-58).
The Odyssey AUV Series uses a Lithium-ion Polymer battery which is able to supply the necessary power for a limited mission time. The current method of recharge includes surfacing the AUV, opening the vehicle, removing the battery from the vehicle and recharging the battery. A different approach is proposed which uses an inductive coupler and power electronics to conduct a battery charge without opening the vehicle or removing the battery.
by Bryan D. Miller.
S.M.
Nav.E.
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Jensen, Harold Franklin. „Variable buoyancy system metric“. Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/58193.
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Thesis (S.M.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 111-112).
Over the past 20 years, underwater vehicle technology has undergone drastic improvements, and vehicles are quickly gaining popularity as a tool for numerous oceanographic tasks. Systems used on the vehicle to alter buoyancy, or variable buoyancy (VB) systems, have seen only minor improvements during the same time period. Though current VB systems are extremely robust, their lack of performance has become a hinderance to the advancement of vehicle capabilities. This thesis first explores the current status of VB systems, then creates a model of each system to determine performance. Second, in order to quantitatively compare fundamentally different VB systems, two metrics, [beta]m and [beta]vol, are developed and applied to current systems. By determining the ratio of performance to size, these metrics give engineers a tool to aid VB system development. Finally, the fundamental challenges in developing more advanced VB systems are explored, and a couple of technologies are investigated for their potential use in new systems.
by Harold Franklin Jensen III.
S.M.
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Assanis, Dennis N. „A computer simulation of the turbocharged turocompounded diesel engine system for studies of low heat rejection engine performance“. Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15089.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Bibliography: leaves 135-140.
by Dionissios Nikolaou Assanis.
Ph.D.
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Cheung, King-bong Sebastian, und 張敬邦. „A computer visualization system for multiple submerged buoyant jets from ocean outfalls“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31224167.
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Louw, Gavin Shaun. „Monitoring the dynamics of the Agulhas Current System off Port Edward, Kwazulu-Natal“. Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/2032.
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Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Oceanography
in the Faculty of Applied Sciences
at the Cape Peninsula University of TechnologyIn order to validate remote sensing products and to provide data for model assimilation, a real-time monitoring line consisting of three moorings was deployed across the Agulhas Current off Port Edward, South Africa. This deployment formed part of a Technology and Human Resource for Industry Programme (THRIP) funded initiative to develop a real-time mooring system capable of measuring ocean parameters in the Agulhas Current during 2011. The slope and offshore moorings displayed a distinct stratified regime within the Agulhas Current, a northeastward flowing Agulhas Undercurrent and the southwestward flowing Agulhas Current. Three major reversal events, with northeastward currents occurred on 23 July, 02 September and on 11 October 2011. All current reversals caused a decrease in current velocity. The Agulhas Undercurrent was a persistent feature and average velocities between the line of moorings ranged between 13.38 cm/s and 15.52 cm/s. The results obtained from the mooring systems were consistent in terms of velocity, direction and hydrographic properties of the Agulhas Current as described in previous literature. The low directional variability in the surface layers at the offshore mooring and dominant southwestward flow, except during reversal events indicate the strong influence of the Agulhas Current in this region. The inshore mooring showed less occurrences of the Agulhas Undercurrent if northward flow in the bottom layers was to be considered as signs of the Agulhas Undercurrent. General current characteristics as well as the characterisation of the mesoscale features affecting the coast off Port Edward was accomplished through the use of the in situ moorings. All current reversals encountered were associated with the process of vortex shedding from the Natal Bight. These events may be related to the shedding of the Durban Cyclonic Eddy from its origin in the Natal Bight. Data from the offshore mooring suggested that for monitoring Agulhas Current core dynamics, it was ideally placed as highest surface velocities were measured by this mooring system. The slope mooring recorded highest velocities within the Agulhas Undercurrent and was thus ideally placed to measure the Agulhas Undercurrent’s core. Shelf dynamics were under the influence of the Agulhas Current and northerly current reversals and were aptly recorded by the inshore mooring which was placed on the continental shelf, close to the shelf break.
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Roth, Michael J. „A coastal air-ocean coupled system for the East Asian marginal seas“. Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA406235.
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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, Sept. 2001.Thesis advisor, Chu, Peter C. "September 2001." Includes bibliographical references (p. 567-570). Also available in print.
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Mantellini, Mattia <1993>. „Optimization of the power electronics system associated with ocean wave electric generators“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10151/1/Optimization%20of%20the%20power%20electronics%20system%20associated%20with%20ocean%20wave%20electric%20generators%20-%20Mantellini%20IBES%2034th%20cycle.pdf.
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The present thesis is focused on wave energy, which is a particular kind of ocean energy, and is based on the activity carried out during the EU project SEA TITAN. The main scope of this work is the design of a power electronic section for an innovative wave energy extraction system based on a switched-reluctance machine.
In the first chapter, the general features of marine wave energy harvesting are treated. The concept of Wave Energy Converter (WEC) is introduced as well as the mathematical description of the waves, their characterization and measurement, the WEC classification, the operating principles and the standardization framework. Also, detailed considerations on the environmental impact are presented. The SEA TITAN project is briefly described.
The second chapter is dedicated to the technical issues of the SEA TITAN project, such as the operating principle, the performance optimization carried out in the project, the main innovations as well as interesting demonstrations on the behavior of the generator and its control.
In the third chapter, the power electronics converters of SEA TITAN are described, and the design choices, procedures and calculations are shown, with a further insight into the application given by analyzing the MATLAB Simulink model of the system and its control scheme.
Experimental tests are reported in the fourth chapter, with graphs and illustrations of the power electronic apparatus interfaced with the real machine.
Finally, the conclusion in the fifth chapter offers a global overview of the project and opens further development pathways.
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Melato, Lebohang Innocentia. „Characterization of the Carbonate System across the Agulhas and Agulhas Return Currents“. Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15745.
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In this study, we investigate the role that the solubility and biological pumps have on CO₂ variability across the Agulhas Current system ( Agulhas Current and the Agulhas Return Current). The Agulhas Current system transports heat and salt from the Indian Ocean into the South Atlantic Ocean via the Agulhas leakage, which influences the Atlantic Meridional Overturning Circulation (AMOC). This study presents for the first time a characterization of the role the Agulhas Current system (Agulhas and Agulhas Return Currents) has on the uptake of anthropogenic CO₂. Fugacity of carbon dioxide (fCO₂ ) values were obtained from a ship-based underway pCO₂ (partial pressure of carbon dioxide) system and the air-sea CO₂ fluxes were computed using 6-hourly wind speeds from the NOAA Blended Sea Winds. An experiment was conducted during the Crossroads scientific monitoring line in May 2013, where surface dissolved inorganic carbon, total alkalinity and CO₂ flux were compared between the Agulhas and Agulhas Return Currents and the region directly south over the Agulhas Plateau. Our findings highlighted that the solubility and biological pumps played minimal to no role in the drawdown of carbon across the sub-Tropical zone and the Agulhas Current system (Agulhas and Agulhas Return Currents), due to opposing effect between chlorophyll and temperature on pCO₂ that explained why although there was carbon drawdown by primary production in the Agulhas and Agulhas Return Current regions, this does not play a role in enhancing the air-sea exchange of CO₂. The solubility pump was responsible for CO₂ in the sub-Antarctic zone. The biological and solubility pumps were responsible for CO₂ sink in the Agulhas Plateau eddy. The highest CO₂ flux in the study was observed in the Agulhas Plateau eddy at a flux value of -8.12 mmolC.m-².day-¹ due to the cooler mean sea surface temperature of ~16.5 °C. This is the first time that such as study has been undertaken and aims to provide a better understanding of the role of Western Boundary Currents such as the Agulhas Current has in the uptake of CO₂.
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Ji, Ming. „Integrated optimization and simulation model for resource acquisition and utilization : an application to ocean/river articulated tug/barge system“. Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43363.
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Gosnell, Sawyer Ross. „Numerical modeling of induced diffuse flow in seafloor hydrothermal system“. Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-08252006-125256/.
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Liao, Te-San. „Modeling and cost analysis of global logistics and manufacturing system“. Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42803.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Operations Research Center, 1997.Includes bibliographical references (leaves 56-57).
by Te-San Liao.
S.M.