Dissertations / Theses on the topic 'Ocean engineering'
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1
Yttervik, Rune. "Ocean current Variability in Relation to Offshore Engineering." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-499.
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This work adresses ocean current variability in relation to offshore engineering.
The offshore oil and gas activity has up until recently taken place mainly on the continental shelves around the world. During the last few years, however, the industry has moved past the continental shelf edge and down the continental slope towards increasingly deeper waters. In deep water locations, marine structures may span large spaces, marine operations may become more complicated and require longer time for completion and the effect of the surface waves is diminished. Therefore, the spatial and temporal variability of the current is expected to become more important in design and planning than before.
The flow of water in the oceans of the world takes place on a wide variety of spatial scales, from the main forms of the global ocean circulation (~km), to the microstructure (~mm) of boundary layer turbulence. Similarly, the temporal variability is also large. In one end of the scale we find variations that take place over several decades, and in the other end we find small-scale turbulence (~seconds). Different features of the flow are driven by different mechanisms. Several processes and properties (stratification1, sloping boundary, Coriolis effect, friction, internal waves, etc.) interact on the continental slope to create a highly variable flow environment. Analysis of a set of observed data that were recorded close to the seabed on the continental slope west of Norway are presented. The data suggest that some strong and abrupt current events (changes in flow speed of ~0.4 m/s in just a couple of hours) were caused by motions of the deep pycnocline2, driven by variations in the surface wind field. This conjecture is partly supported by numerical simulations of an idealised continental slope and a two-layer ocean. The data also contains an event during which the flow direction at the sea bed changed very rapidly (within a few minutes) from down-slope to up-slope flow. The change in speed during this event was as high as 0.5 m/s.
Another data set has been analyzed in order to illustrate the spatial variation in the current that can sometimes be found. It is shown that the flow in the upper layer is virtually decoupled from the flow in the lower layer at a location west of Norway. This is either caused by bottom topography, stratification or both.
High variability of the current presents new requirements to the way that the current should be modelled by the offshore engineer. For instance, it is necessary to consider which type of operation/structure that is to be carried out or installed before selecting design current conditions. Reliable methods for obtaining design current conditions for a given deep water location have yet to be developed, only a brief discussion of this topic is given herein.
It is shown, through calculations of VIV-response and simulations of typical marine operations, that the variability of the current will sometimes have a significant effect on the response/operation.
1Vertical distribution of density. In a stratified ocean or flow, the density of the water varies in the vertical direction.
2pycnocline=density surface between water masses. The pycnocline between two water masses of different density is defined by the maximum of the density gradient.
2
Langlois, Gilles. "Diaphragm forming : innovation and application to ocean engineering." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37530.
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Shen, Guoling 1967. "Approximation with interval B-splines for robust reverse engineering." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43456.
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Swezey, Matthew Michael. "Ocean acoustic uncertainty for submarine applications." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104274.
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Thesis: S.M. in Naval Architecture and Marine Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Thesis: S.M. in Mechanical Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 119-125).
The focus of this research is to study the uncertainties forecast by multi-resolution ocean models and quantify how those uncertainties affect the pressure fields estimated by coupled ocean models. The quantified uncertainty can then be used to provide enhanced sonar performance predictions for tactical decision aides. High fidelity robust modeling of the oceans can resolve various scale processes from tidal shifts to mesoscale phenomena. These ocean models can be coupled with acoustic models that account for variations in the ocean environment and complex bathymetry to yield accurate acoustic field representations that are both range and time independent. Utilizing the MIT Multidisciplinary Environmental Assimilation System (MSEAS) implicit two-way nested primitive-equation ocean model and Error Subspace Statistical Estimation scheme (ESSE), coupled with three-dimensional-in-space (3D) parabolic equation acoustic models, we conduct a study to understand and determine the effects of ocean state uncertainty on the acoustic transmission loss. The region of study is focused on the ocean waters surrounding Taiwan in the East China Sea. This region contains complex ocean dynamics and topography along the critical shelf-break region where the ocean acoustic interaction is driven by several uncertainties. The resulting ocean acoustic uncertainty is modeled and analyzed to quantify sonar performance and uncertainty characteristics with respect to submarine counter detection. Utilizing cluster based data analysis techniques, the relationship between the resulting acoustic field and the uncertainty in the ocean model can be characterized. Furthermore, the dynamic transitioning between the clustered acoustic states can be modeled as Markov processes. This analysis can be used to enhance not only submarine counter detection aides, but it may also be used for several applications to enhance understanding of the capabilities and behavior of uncertainties of acoustic systems operating in the complex ocean environment.
by Matthew Michael Swezey.
S.M. in Naval Architecture and Marine Engineering
S.M. in Mechanical Engineering
5
Shah, Vikrant P. "Design considerations for engineering autonomous underwater vehicles." Online version of original thesis, 2007. http://hdl.handle.net/1912/1883.
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Balzola, Ricardo 1971. "Balancing container inventories for ocean carriers." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9494.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.Includes bibliographical references (leaves 59-60).
Over the last twenty years the transportation industry has undergone a dramatic shift into container operations. The advantages of this mode of transportation are numerous, especially for the ocean carriers. The use of containers adds a high degree of versatility to their ships and increases the utilization of the vessels by means of a remarkable decrease in the loading and unloading operations time. However, the introduction of the containers adds, as well, a considerable investment cost to an industry that was already very capital intensive. The pressure of the high cost investment in equipment in addition to a remarkable competition in the sector forces every player in the industry to try to obtain the maximum efficiency in the utilization of its assets. Global trade is not in general balanced, and so the demand for containers at the different ports of the world varies greatly. As a result of this unbalanced situation, empty containers must be reallocated from mainly importing areas to those at which the overall outflow of freight is larger than the inflow. Managing the container inventory and the container reallocation, subject to the particular requirements of the industry and the present and future demand is known as the Container Allocation Problem. The purpose of this thesis is the development of a model for this problem so as to maximize the profit to be obtained from the management of a shipping line container inventory. The container avocation problem is modeled by the user of a large-scale, multi-stage stochastic network formulation that incorporates the uncertainty factor in the demand side of the problem. This network formulation captures the space-time dynamics of the reallocation process while using an objective function that minimizes the cost of the container operations in the long run. A continuous rolling horizon to limit the number of nodes in the network is used in the modeling of this system so as to make this problem tractable. Finally, a solution algorithm for this problem is proposed. The algorithm decomposes the initial non-linear network formulation into an iteration of successive linear approximations that can be solved via a classical linear programming method.
by Ricardo Balzola.
M.Eng.
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Vaskov, Alex Kikeri. "Technological review of deep ocean manned submersibles." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74911.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis. Vita.
Includes bibliographical references (p. 63-65).
James Cameron's dive to the Challenger Deep in the Deepsea Challenger in March of 2012 marked the first time man had returned to the Mariana Trench since the Bathyscaphe Trieste's 1960 dive. Currently little is known about the geological processes and ecosystems of the deep ocean. The Deepsea Challenger is equipped with a plethora of instrumentation to collect scientific data and samples. The development of the Deepsea Challenger has sparked a renewed interest in manned exploration of the deep ocean. Due to the immense pressure at full ocean depth, a variety of advanced systems and materials are used on Cameron's dive craft. This paper provides an overview of the many novel features of the Deepsea Challenger as well as related features of past vehicles that have reached the Challenger Deep. Four key areas of innovation are identified: buoyancy materials, pilot sphere construction/instrument housings, lighting, and battery power. An in depth review of technological development in these areas is provided, as well as a glimpse into future manned submersibles and their technologies of choice.
by Alex Kikeri Vaskov.
S.B.
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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.
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Desroches, Alexander S. (Alexander Stephen). "Calculation of extreme towline tension during open ocean towing." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/17441.
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Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1997, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997.Includes bibliographical references (leaf 60).
by Alexander S. Deroches.
M.S.
Nav.E.
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Kalmikov, Alexander G. "Uncertainty Quantification in ocean state estimation." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79291.
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Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 158-160).
Quantifying uncertainty and error bounds is a key outstanding challenge in ocean state estimation and climate research. It is particularly difficult due to the large dimensionality of this nonlinear estimation problem and the number of uncertain variables involved. The "Estimating the Circulation and Climate of the Oceans" (ECCO) consortium has developed a scalable system for dynamically consistent estimation of global time-evolving ocean state by optimal combination of ocean general circulation model (GCM) with diverse ocean observations. The estimation system is based on the "adjoint method" solution of an unconstrained least-squares optimization problem formulated with the method of Lagrange multipliers for fitting the dynamical ocean model to observations. The dynamical consistency requirement of ocean state estimation necessitates this approach over sequential data assimilation and reanalysis smoothing techniques. In addition, it is computationally advantageous because calculation and storage of large covariance matrices is not required. However, this is also a drawback of the adjoint method, which lacks a native formalism for error propagation and quantification of assimilated uncertainty. The objective of this dissertation is to resolve that limitation by developing a feasible computational methodology for uncertainty analysis in dynamically consistent state estimation, applicable to the large dimensionality of global ocean models. Hessian (second derivative-based) methodology is developed for Uncertainty Quantification (UQ) in large-scale ocean state estimation, extending the gradient-based adjoint method to employ the second order geometry information of the model-data misfit function in a high-dimensional control space. Large error covariance matrices are evaluated by inverting the Hessian matrix with the developed scalable matrix-free numerical linear algebra algorithms. Hessian-vector product and Jacobian derivative codes of the MIT general circulation model (MITgcm) are generated by means of algorithmic differentiation (AD). Computational complexity of the Hessian code is reduced by tangent linear differentiation of the adjoint code, which preserves the speedup of adjoint checkpointing schemes in the second derivative calculation. A Lanczos algorithm is applied for extracting the leading rank eigenvectors and eigenvalues of the Hessian matrix. The eigenvectors represent the constrained uncertainty patterns. The inverse eigenvalues are the corresponding uncertainties. The dimensionality of UQ calculations is reduced by eliminating the uncertainty null-space unconstrained by the supplied observations. Inverse and forward uncertainty propagation schemes are designed for assimilating observation and control variable uncertainties, and for projecting these uncertainties onto oceanographic target quantities. Two versions of these schemes are developed: one evaluates reduction of prior uncertainties, while another does not require prior assumptions. The analysis of uncertainty propagation in the ocean model is time-resolving. It captures the dynamics of uncertainty evolution and reveals transient and stationary uncertainty regimes. The system is applied to quantifying uncertainties of Antarctic Circumpolar Current (ACC) transport in a global barotropic configuration of the MITgcm. The model is constrained by synthetic observations of sea surface height and velocities. The control space consists of two-dimensional maps of initial and boundary conditions and model parameters. The size of the Hessian matrix is 0(1010) elements, which would require 0(60GB) of uncompressed storage. It is demonstrated how the choice of observations and their geographic coverage determines the reduction in uncertainties of the estimated transport. The system also yields information on how well the control fields are constrained by the observations. The effects of controls uncertainty reduction due to decrease of diagonal covariance terms are compared to dynamical coupling of controls through off-diagonal covariance terms. The correlations of controls introduced by observation uncertainty assimilation are found to dominate the reduction of uncertainty of transport. An idealized analytical model of ACC guides a detailed time-resolving understanding of uncertainty dynamics. Keywords: Adjoint model uncertainty, sensitivity, posterior error reduction, reduced rank Hessian matrix, Automatic Differentiation, ocean state estimation, barotropic model, Drake Passage transport.
by Alexander G. Kalmikov.
Ph.D.
11
Ueckermann, Mattheus Percy. "High order hybrid discontinuous Galerkin regional ocean modelling." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87984.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 343-357).
Accurate modeling of physical and biogeochemical dynamics in coastal ocean regions is required for multiple scientific and societal applications, covering a wide range of time and space scales. However, in light of the strong nonlinearities observed in coastal regions and in biological processes, such modeling is challenging. An important subject that has been largely overlooked is the numerical requirements for regional ocean simulation studies. Major objectives of this thesis are to address such computational questions for non-hydrostatic multiscale flows and for biogeochemical interactions, and to derive and develop numerical schemes that meet these requirements, utilizing the latest advances in computational fluid dynamics. We are interested in studying nonlinear, transient, and multiscale ocean dynamics over complex geometries with steep bathymetry and intricate coastlines, from sub-mesoscales to basin-scales. These dynamical interests, when combined with our requirements for accurate, efficient and flexible ocean modeling, led us to develop new variable resolution, higher-order and non-hydrostatic ocean modeling schemes. Specifically, we derived, developed and applied new numerical schemes based on the novel hybrid discontinuous Galerkin (HDG) method in combination with projection methods. The new numerical schemes are first derived for the Navier-Stokes equations. To ensure mass conservation, we define numerical fluxes that are consistent with the discrete divergence equation. To improve stability and accuracy, we derive a consistent HDG stability parameter for the pressure-correction equation. We also apply a new boundary condition for the pressure-corrector, and show the form and origin of the projection method's time-splitting error for a case with implicit diffusion and explicit advection. Our scheme is implemented for arbitrary, mixed-element unstructured grids using a novel quadrature-free integration method for a nodal basis, which is consistent with the HDG method. To prevent numerical oscillations, we design a selective high-order nodal limiter. We demonstrate the correctness of our new schemes using a tracer advection benchmark, a manufactured solution for the steady diffusion and stokes equations, and the 2D lock-exchange problem. These numerical schemes are then extended for non-hydrostatic, free-surface, variable-density regional ocean dynamics. The time-splitting procedure using projection methods is derived for non-hydrostatic or hydrostatic, and nonlinear free-surface or rigid-lid, versions of the model. We also derive consistent HDG stability parameters for the free-surface and non-hydrostatic pressure-corrector equations to ensure stability and accuracy. New boundary conditions for the free-surface-corrector and pressure-corrector are also introduced. We prove that these conditions lead to consistent boundary conditions for the free-surface and pressure proper. To ensure discrete mass conservation with a moving free-surface, we use an arbitrary Lagrangian- Eulerian (ALE) moving mesh algorithm. These schemes are again verified, this time using a tidal flow problem with analytical solutions and a 3D lock-exchange benchmark. We apply our new numerical schemes to evaluate the numerical requirements of the coupled biological-physical dynamics. We find that higher-order schemes are more accurate at the same efficiency compared to lower-order (e.g. second-order) accurate schemes when modeling a biological patch. Due to decreased numerical dissipation, the higher-order schemes are capable of modeling biological patchiness over a sustained duration, while the lower-order schemes can lose significant biomass after a few non-dimensional times and can thus solve erroneous nonlinear dynamics. Finally, inspired by Stellwagen Bank in Massachusetts Bay, we study the effect of non-hydrostatic physics on biological productivity and phytoplankton fields for tidally-driven flows over an idealized bank. We find that the non-hydrostatic pressure and flows are important for biological dynamics, especially when flows are supercritical. That is, when the slope of the topography is larger than the slope of internal wave rays at the tidal frequency. The non-hydrostatic effects increase with increasing nonlinearity, both when the internal Froude number and criticality parameter increase. Even in cases where the instantaneous biological productivity is not largely modified, we find that the total biomass, spatial variability and patchiness of phytoplankton can be significantly altered by non-hydrostatic processes. Our ultimate dynamics motivation is to allow quantitative simulation studies of fundamental nonlinear biological-physical dynamics in coastal regions with complex bathymetric features such as straits, sills, ridges and shelfbreaks. This thesis develops the necessary numerical schemes that meet the stringent accuracy requirements for these types of flows and dynamics.
by Mattheus Percy Ueckermann.
Ph. D.
12
Burton, Lisa Janelle. "Modeling coupled physics and biology in ocean straits." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49878.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 149-153).
In this thesis, we conduct research toward understanding coupled physics-biology processes in ocean straits. Our focus is on new analytical studies and higher-order simulations of idealized dynamics that are relevant to generic biological processes. The details of coupled physics-biology models are reviewed and an in-depth global equilibrium and local stability analysis of a Nutrient-Phytoplankton-Zooplankton (NPZ) model is performed. This analysis includes parameter studies and methods to evaluate parameter sensitivity, especially in the case where some system parameters are unknown. As an initial step toward investigating the interaction between physics and biology in ocean straits, we develop and verify a new coupled physics-biology model for two-dimensional idealized physical processes including tides and apply it to the San Bernardino Strait in the Philippine Archipelago. This two-dimensional numerical model is created on a structured grid using operator splitting and masking. This model is able to accurately represent biology for various physical flows, including advection-dominated flows over discontinuities, by using the Weighted Essentially Non-Oscillatory (WENO) scheme. The numerical model is verified against a Discontinuous-Galerkin (DG) numerical scheme on an unstructured grid. Several simulations of tidal flow are completed using bathymetry and flow magnitudes comparable to those found in the San Bernardino Strait with different sets of parameters, tidal periods, and levels of diffusion.
(cont.) Results are discussed and compared to those of a three-dimensional modeling system. New results include: new methods for analyzing stability, the robust two-dimensional model designed to best represent advection-dominant flows with minimal numerical diffusion and computational time, and a novel technique to initialize three-dimensional biology fields using satellite data. Additionally, application of the two-dimensional model with tidal forcing to the San Bernardino Strait reveals that flow frequencies have strong influence on biology, as very fast oscillations act to stabilize biology in the water column, while slower frequencies provide sufficient transport for increased biological activity.
by Lisa Janelle Burton.
S.M.
13
Viglundsson, Viglundur Thor. "Modern fleet planning methods for ocean liner service." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35008.
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Mirhi, Mohamad H. (Mohamad Hussein). "Design of interactive maps for ocean dynamics data." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121860.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references.
Comprehensive spatiotemporal modeling and forecasting systems for ocean dynamics necessitate robust and efficient data delivery and visualization techniques. The multi-disciplinary simulation, estimation, and assimilation systems group at MIT (MSEAS) focuses on capturing and predicting diverse ocean dynamics, including physics, acoustics, and biology on varied scales, thereby developing new methods for multi-resolution ocean prediction and analysis, including data generation and assimilation. The group has primarily used non-interactive ocean plots to visualize its simulated and measured data. Although these maps and sections allow for analysis of ocean physics and the underlying numerical schemes, more interactive maps provide more user control over depicted data, allowing easier study and pattern identification on multiple scales. Integrating static and geospatial data in dynamic visualization creates a heightened viewpoint for analysis, enhances ocean monitoring and prediction, and contributes to building scientific knowledge. This thesis focuses on explaining the motivation behind and the methodologies applied in designing these interactive maps.
by Mohamad Mirhi.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Mechanical Engineering
15
Tzelepis, Vasileios. "Electromechanics of an Ocean Current Turbine." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2112.
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The development of a numeric simulation for predicting the performance of an Ocean Current Energy Conversion System is presented in this thesis along with a control system development using a PID controller for the achievement of specified rotational velocity set-points. In the beginning, this numeric model is implemented in MATLAB/Simulink® and it is used to predict the performance of a three phase squirrel single-cage type induction motor/generator in two different cases. The first case is a small 3 meter rotor diameter, 20 kW ocean current turbine with fixed pitch blades, and the second case a 20 meter, 720 kW ocean current turbine with variable pitch blades. Furthermore, the second case is also used for the development of a Voltage Source Variable Frequency Drive for the induction motor/generator. Comparison among the Variable Frequency Drive and a simplified model is applied. Finally, the simulation is also used to estimate the average electric power generation from the 720 kW Ocean Current Energy Conversion System which consists of an induction generator and an ocean current turbine connected with a shaft which modeled as a mechanical vibration system.
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Greenwood, Charles. "The impact of large scale wave energy converter farms on the regional wave climate." Thesis, University of the Highlands and Islands, 2016. https://pure.uhi.ac.uk/portal/en/studentthesis/the-impact-of-large-scale-wave-energy-converter-farms-on-the-regional-wave-climate(e734db00-2108-48f9-b162-a1fc85ef61d6).html.
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Lo, Hong Kam. "Dynamic ship routing through stochastic, spatially dependent ocean currents /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487759055156018.
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Henry, Legena Albertha. "A study of ocean wave statistical properties using nonlinear, directional, phase-resolved ocean wave-field simulations." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1912/3230.
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Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), February 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 327-334).
In the present work, we study the statistics of wavefields obtained from non-linear phase-resolved simulations. The numerical model used to generate the waves models wave-wave interactions based on the fully non-linear Zakharov equations. We vary the simulated wavefield's input spectral properties: directional spreading function, Phillips parameter and peak shape parameter. We then investigate the relationships between a wavefield's input spectral properties and its output physical properties via statistical analysis. We investigate surface elevation distribution, wave definition methods in a nonlinear wavefield with a two-dimensional wavenumber, defined waves' distributions, and the occurrence and spacing of large wave events.
by Legena Albertha Henry.
S.M.
19
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
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Lolla, Sri Venkata Tapovan. "Path planning and adaptive sampling in the coastal ocean." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103438.
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Thesis: Ph. D. in Mechanical Engineering and Computation, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.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 299-315).
When humans or robots operate in complex dynamic environments, the planning of paths and the collection of observations are basic, indispensable problems. In the oceanic and atmospheric environments, the concurrent use of multiple mobile sensing platforms in unmanned missions is growing very rapidly. Opportunities for a paradigm shift in the science of autonomy involve the development of fundamental theories to optimally collect information, learn, collaborate and make decisions under uncertainty while persistently adapting to and utilizing the dynamic environment. To address such pressing needs, this thesis derives governing equations and develops rigorous methodologies for optimal path planning and optimal sampling using collaborative swarms of autonomous mobile platforms. The application focus is the coastal ocean where currents can be much larger than platform speeds, but the fundamental results also apply to other dynamic environments. We first undertake a theoretical synthesis of minimum-time control of vehicles operating in general dynamic flows. Using various ideas rooted in non-smooth calculus, we prove that an unsteady Hamilton-Jacobi equation governs the forward reachable sets in any type of Lipschitz-continuous flow. Next, we show that with a suitable modification to the Hamiltonian, the results can be rigorously generalized to perform time-optimal path planning with anisotropic motion constraints and with moving obstacles and unsafe 'forbidden' regions. We then derive a level-set methodology for distance-based coordination of swarms of vehicles operating in minimum time within strong and dynamic ocean currents. The results are illustrated for varied fluid and ocean flow simulations. Finally, the new path planning system is applied to swarms of vehicles operating in the complex geometry of the Philippine Archipelago, utilizing realistic multi-scale current predictions from a data-assimilative ocean modeling system. In the second part of the thesis, we derive a theory for adaptive sampling that exploits the governing nonlinear dynamics of the system and captures the non-Gaussian structure of the random state fields. Optimal observation locations are determined by maximizing the mutual information between the candidate observations and the variables of interest. We develop a novel Bayesian smoother for high-dimensional continuous stochastic fields governed by general nonlinear dynamics. This smoother combines the adaptive reduced-order Dynamically-Orthogonal equations with Gaussian Mixture Models, extending linearized Gaussian backward pass updates to a nonlinear, non-Gaussian setting. The Bayesian information transfer, both forward and backward in time, is efficiently carried out in the evolving dominant stochastic subspace. Building on the foundations of the smoother, we then derive an efficient technique to quantify the spatially and temporally varying mutual information field in general nonlinear dynamical systems. The globally optimal sequence of future sampling locations is rigorously determined by a novel dynamic programming approach that combines this computation of mutual information fields with the predictions of the forward reachable set. All the results are exemplified and their performance is quantitatively assessed using a variety of simulated fluid and ocean flows. The above novel theories and schemes are integrated so as to provide real-time computational intelligence for collaborative swarms of autonomous sensing vehicles. The integrated system guides groups of vehicles along predicted optimal trajectories and continuously improves field estimates as the observations predicted to be most informative are collected and assimilated. The optimal sampling locations and optimal trajectories are continuously forecast, all in an autonomous and coordinated fashion.
by Sri Venkata Tapovan Lolla.
Ph. D. in Mechanical Engineering and Computation
21
Narayanan, Subramani Deepak. "Probabilistic regional ocean predictions : stochastic fields and optimal planning." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115733.
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Thesis: Ph. D. in Mechanical Engineering and Computation, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Cataloged from PDF version of thesis. "Submitted to the Department of Mechanical Engineering and Center for Computational Engineering."
Includes bibliographical references (pages 253-268).
The coastal ocean is a prime example of multiscale nonlinear fluid dynamics. Ocean fields in such regions are complex, with multiple spatial and temporal scales and nonstationary heterogeneous statistics. Due to the limited measurements, there are multiple sources of uncertainties, including the initial conditions, boundary conditions, forcing, parameters, and even the model parameterizations and equations themselves. To reduce uncertainties and allow long-duration measurements, the energy consumption of ocean observing platforms need to be optimized. Predicting the distributions of reachable regions, time-optimal paths, and risk-optimal paths in uncertain, strong and dynamic flows is also essential for their optimal and safe operations. Motivated by the above needs, the objectives of this thesis are to develop and apply the theory, schemes, and computational systems for: (i) Dynamically Orthogonal ocean primitive-equations with a nonlinear free-surface, in order to quantify uncertainties and predict probabilities for four-dimensional (time and 3-d in space) coastal ocean states, respecting their nonlinear governing equations and non-Gaussian statistics; (ii) Stochastic Dynamically Orthogonal level-set optimization to rigorously incorporate realistic ocean flow forecasts and plan energy-optimal paths of autonomous agents in coastal regions; (iii) Probabilistic predictions of reachability, time-optimal paths and risk-optimal paths in uncertain, strong and dynamic flows. For the first objective, we further develop and implement our Dynamically Orthogonal (DO) numerical schemes for idealized and realistic ocean primitive equations with a nonlinear free-surface. The theoretical extensions necessary for the free-surface are completed. DO schemes are researched and DO terms, functions, and operations are implemented, focusing on: state variable choices; DO norms; DO condition for flows with a dynamic free-surface; diagnostic DO equations for pressure, barotropic velocities and density terms; non-polynomial nonlinearities; semi-implicit time-stepping schemes; and re-orthonormalization consistent with leap-frog time marching. We apply the new DO schemes, as well as their theoretical extensions and efficient serial implementation to forecast idealized-to-realistic stochastic coastal ocean dynamics. For the realistic simulations, probabilistic predictions for the Middle Atlantic Bight region, Northwest Atlantic, and northern Indian ocean are showcased. For the second objective, we integrate data-driven ocean modeling with our stochastic DO level-set optimization to compute and study energy-optimal paths, speeds, and headings for ocean vehicles in the Middle Atlantic Bight region. We compute the energy-optimal paths from among exact time-optimal paths. For ocean currents, we utilize a data-assimilative multiscale re-analysis, combining observations with implicit two-way nested multi-resolution primitive-equation simulations of the tidal-to-mesoscale dynamics in the region. We solve the reduced-order stochastic DO level-set partial differential equations (PDEs) to compute the joint probability of minimum arrival-time, vehicle-speed time-series, and total energy utilized. For each arrival time, we then select the vehicle-speed time-series that minimize the total energy utilization from the marginal probability of vehicle-speed and total energy. The corresponding energy-optimal path and headings be obtained through a particle backtracking equation. For the missions considered, we analyze the effects of the regional tidal currents, strong wind events, coastal jets, shelfbreak front, and other local circulations on the energy-optimal paths. For the third objective, we develop and apply stochastic level-set PDEs that govern the stochastic time-optimal reachability fronts and paths for vehicles in uncertain, strong, and dynamic flow fields. To solve these equations efficiently, we again employ their dynamically orthogonal reduced-order projections. We develop the theory and schemes for risk-optimal planning by combining decision theory with our stochastic time-optimal planning equations. The risk-optimal planning proceeds in three steps: (i) obtain predictions of the probability distribution of environmental flows, (ii) obtain predictions of the distribution of exact time-optimal paths for the forecast flow distribution, and (iii) compute and minimize the risk of following these uncertain time-optimal paths. We utilize the new equations to complete stochastic reachability, time-optimal and risk-optimal path planning in varied stochastic quasi-geostrophic flows. The effects of the flow uncertainty on the reachability fronts and time-optimal paths is explained. The risks of following each exact time-optimal path is evaluated and risk-optimal paths are computed for different risk tolerance measures. Key properties of the risk-optimal planning are finally discussed. Theoretically, the present methodologies are PDE-based and compute stochastic ocean fields, and optimal path predictions without heuristics. Computationally, they are several orders of magnitude faster than direct Monte Carlo. Such technologies have several commercial and societal applications. Specifically, the probabilistic ocean predictions can be input to a technical decision aide for a sustainable fisheries co-management program in India, which has the potential to provide environment friendly livelihoods to millions of marginal fishermen. The risk-optimal path planning equations can be employed in real-time for efficient ship routing to reduce greenhouse gas emissions and save operational costs.
by Deepak Narayanan Subramani.
Ph. D. in Mechanical Engineering and Computation
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Heubel, Eric Vincent. "Parameter estimation and adaptive modeling studies in ocean mixing." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/46155.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 119-121).
In this thesis, we explore the different methods for parameter estimation in straightforward diffusion problems and develop ideas and distributed computational schemes for the automated evaluation of physical and numerical parameters of ocean models. This is one step of "adaptive modeling." Adaptive modeling consists of the automated adjustment of self-evaluating models in order to best represent an observed system. In the case of dynamic parameterizations, self-modifying schemes are used to learn the correct model for a particular regime as the physics change and evolve in time. The parameter estimation methods are tested and evaluated on one-dimensional tracer diffusion problems. Existing state estimation methods and new filters, such as the unscented transform Kalman filter, are utilized in carrying out parameter estimation. These include the popular Extended Kalman Filter (EKF), the Ensemble Kalman Filter (EnKF) and other ensemble methods such as Error Subspace Statistical Estimation (ESSE) and Ensemble Adjustment Kalman Filter (EAKF), and the Unscented Kalman Filter (UKF). Among the aforementioned recursive state estimation methods, the so-called "adjoint method" is also applied to this simple study. Finally, real data is examined for the applicability of such schemes in real-time forecasting using the MIT Multidisciplinary Simulation, Estimation, and Assimilation System (MSEAS). The MSEAS model currently contains the free surface hydrostatic primitive equation model from the Harvard Ocean Prediction System (HOPS), a barotropic tidal prediction scheme, and an objective analysis scheme, among other models and developing routines. The experiment chosen for this study is one which involved the Monterey Bay region off the coast of California in 2006 (MB06). Accurate vertical mixing parameterizations are essential in this well known upwelling region of the Pacific. In this realistic case, parallel computing will be utilized by scripting code runs in C-shell. The performance of the simulations with different, parameters is evaluated quantitatively using Pattern Correlation Coefficient, Root Mean Squared error, and bias error. Comparisons quantitatively determined the most adequate model setup.
by Eric Vincent Heubel.
M.Eng.
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Wells, Christopher Everett. "Analysis of SeaWiFS Ocean Color Algorithms for Lake Erie." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1421158613.
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MacHutchon, K. R. "The characterisation of South African sea storms." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/576.
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Oller, Erik D. "Forces and moments due to unsteady motion of an underwater vehicle." Thesis, Cambridge, Massachusetts. Massachusetts Institute of Technology c2003, 2003. http://hdl.handle.net/10945/11032.
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CIVINSThis research examines the effect of unsteady motion on the forces and moments experienced by an underwater vehicle in shallow water. The test platform is the REMUS Autonomous Underwater Vehicle developed by the Woods Hole Oceanographic Institution, although the results are made non-dimensional to be applicable to a wide range of similar shaped vehicles. The experimental model was moved in sinusoidal motion at various submergences, speeds, frequencies of oscillation, and amplitudes of oscillation.
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Naciri, Mamoun. "On wave-wave interactions on the ocean surface." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/47312.
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Headrick, Robert Hugh. "Analysis of Internal Wave induced mode coupling effects on the 1995 SWARM experiment acoustic transmissions." Thesis, Monterey, California. Naval Postgraduate School, 1997. http://hdl.handle.net/10945/7928.
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CIVINSAs part of the Shallow Water Acoustics in a Random Medium (SWARM) experiment, a sixteen element WHOI vertical line array (WVLA) was moored in 70 meters of water off the New Jersey coast. This array was sampled at 1395 Hz or higher for the seven days it was deployed. Tomography sources with carrier frequencies of 224 and 400 Hz were moored about 32 km shoreward, such that the acoustic path was anti-parallel to the primary propagation direction for shelf generated internal wave solitons. Two models for the propagation of normal modes through a 2-D waveguide with solitary internal wave (soliton) scattering included are developed to help in understanding the very complicated mode arrivals seen at the WVLA. The simplest model uses the Preisig and Duda sharp interface approximation for solitons, allowing for rapid analysis of the effects of various numbers of solitons on mode arrival statistics. The second model, using SWARM thermistor string data to simulate the actual SWARM waveguides, is more realistic, but much slower. The analysis of the actual WVLA data yields spread, bias, wander, and intensity fluctuation signals that are modulated at tidal frequencies. The signals are consistent with predicted relationships to the internal wave distributions in the waveguides
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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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Torkelson, Kai Oscar. "Comparative naval architecture analysis of diesel submarines." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/10945/11050.
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CIVINSMany comparative naval architecture analyses of surface ships have been performed, but few published comparative analyses of submarines exist. Of the several design concept papers, reports and studies that have been written on submarines, no exclusively diesel submarine comparative naval architecture analyses have been published. One possible reason for few submarine studies may be the lack of complete and accurate information regarding the naval architecture of foreign diesel submarines. However, with some fundamental submarine design principles, drawings of inboard profiles and plan views, and key assumptions to develop empirical equations, a process can be developed by which to estimate the submarine naval architectural characteristics. comparative naval architecture analysis creates an opportunity to identify new technologies, review the architectural characteristics best suited for submarine missions and to possibly build more effective submarines. An accurate observation is that submarines designed for different missions possess different capabilities. But are these unique capabilities due to differences in submarine naval architecture? Can mission, cost, or other factors affect the architecture? This study examines and compares the naval architecture of selected diesel submarines from data found in open literature. The goal is to determine weight group estimates and analyze whether these estimates provide a relevant comparison of diesel submarine naval architecture.
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Stenard, John K. "Comparative naval architecture of modern foreign submarines." Thesis, Cambridge, Massachusetts : Massachusetts Institute of Technology, 1988. http://hdl.handle.net/10945/22954.
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CIVINSA Comparative design study of ten conventional and nuclear-powered fast attack submarines is performed. Data sources are limited to those available in the open literature. The analysis is confined to those submarines which are of the greatest interest and for which enough design information is available to conduct an adequate study. The data for each of the selected submarines is then parameterized, analyzed, and compared on the basis of design and military capabilities. The design philosophy and top level requirement of each submarine is then inferred from its naval architecture and military capabilities. It is concluded that automation of systems will allow a reduction of crew size, which then permits a larger battery and greater provision, fuel and weapons loadouts. This will lead to greater combat effectiveness due to increased range, attack flexibility, speed, and weapons delivery potential. Keywords: Attack submarines; Nuclear powered submarines; Sizes dimensions comparison; Volume weight displacement; Weapons systems; Command control systems; C3; Submarine engines; Underwater propulsion mobility; Storage batteries, Diesel engines; Mission profiles; Foreign military forces; Theses. (edc)
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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.
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Wojcik, Dennis Michael. "Passive localization of underwater acoustic beacons." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/10945/24212.
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Stackley, Sean Joseph. "Dynamics of full annular rotor rub." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/10945/21799.
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Amy, John Victor. "Outside the Hull Electric Propulsion for a submarine." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/10945/28436.
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Sapone, David Thomas. "A sensitivity study of bow variants on the distribution of sea spray in regular head seas." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/10945/28527.
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There has always been a need and desire to improve upon the operability of ships at sea. The driving force behind making improvements can be safety, economic, or militarily oriented. This paper deals with improving a ship's operability by studying the effects of bow flare on the quantity and distribution of spray across the main deck under varying environmental conditions. A 1:36 scaled model of a 3600 LT on displacement ship, resembling a U.S. Navy FFG-7 class combatant, was used throughout this study. The model was tested with four different bows with varying degrees of flare. A surfactant was added to the towing tank water to reduce the surface tension and increase the Weber Number in order to better simulate spray at the model scale. Environmental conditions imposed were regular head seas of a mean sea state 6 and generated true wind equivalent to 32 knots. One bow form was first tested in ordinary tank water so that a comparison could be made between the two surface tension conditions. A 64% reduction in surface tension was achieved through the addition of the brand name surfactant AEROSOL OT-75. Though this value is relatively great, it corresponds to a Weber Number that is 22 times smaller then the required full scale value. The visual effect on the spray was to cause a finer droplet size and break up of the water sheet that normally is present rolling off the bow. With respect to the measurements taken, the reduction in surface tension resulted in; (a) a smaller volume of spray water being captured, (b) a change in the density distribution of the spray across the main deck, and (c) an increase in the wetted area on the main decking. In the absence of any specific spray criteria in which to judge each bow's performance against, the general trend was to reduce the quantity of spray water delivered and limit its distribution with an increase in the bow flare. The one knuckled bow that was tested performed much worst then any of the conventionally flared bows
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Corrado, Charles N. (Charles Neal). "Mid-frequency acoustic backscattering from finite cylindrical shells and the influence of helical membrane waves." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12563.
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Zhou, Jingfang. "Interval simplex splines for scientific databases." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38060.
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Tracey, Brian Hearne. "An integrated modal approach to surface and volume scattering in ocean acoustic waveguides." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/11280.
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Gougoulidis, Georgios. "MathCAD model for the estimation of cost and main characteristics of air-cushion vehicles in the preliminary design stage." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33563.
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Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2005.Includes bibliographical references (p. 66-67).
In the naval architecture terminology, the term ACV (Air Cushion Vehicle) refers to this category of vehicles, in which a significant portion of the weight (or all the weight) is supported by forces arising from air pressures developed around the craft, as a result of which they hover in close proximity to the sea. Major types are hovercrafts and SES (Surface Effect Ships). A well-designed Air Cushion Vehicle (ACV) is superior to a conventional ship, because it has less drag and requires less horsepower to operate at the same speed. An ACV is much more fuel-efficient than a ship with similar capacity or size. Rising fuel prices and shortages will make ACVs a desirable form of transportation in the future. In order to cover this future trend in marine transportation, a MathCAD model for the estimation of the main characteristics of Air Cushion Vehicles in the preliminary design stage is being developed. This model is based on a statistical analysis of the various parameters of existing crafts. For this reason, a statistical database has been created using publicly available information. A regression analysis has been performed using the data collected and the trend lines for every case have been derived.
(cont.) For the validation of the code, LCAC (Landing Craft Air Cushion) is used as the reference vehicle. The values of LCAC design parameters that are known, are input in the code and crosschecked with the outputs. Iterative procedures have been applied to the code in order to correct the trend lines according to the reference model. The development of this MathCAD model is directly related to the lack of software dealing with the design of ACVs in the market. Conventional ship design tools are widespread and used even by students. On the other hand, ACV design programs are possessed by the companies that design this kind of crafts and are not widely available. In the following pages, together with the analysis of the model developed, the associated theory is presented so that the reader has a complete image of what an ACV is and how it works. Hence, this thesis is not a manual of a program, but a combination of theory and application intended to help the reader-user understand the design process of ACVs.
by Georgios Gougoulidis.
Nav.E.and S.M.
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Bliek, Christian. "Computer methods for design automation." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/35361.
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Black, Scott D. (Scott Donald). "Integrated lifting-surface/Navier-Stokes design and analysis methods for marine propulsors." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10398.
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Manning, Patricia Anne 1965. "Experiemtal investigation of wave coupling on a cylindrical shell with a keel." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/79980.
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Warren, Christopher L. (Christopher Lane). "Prediction of propulsor-induced maneuvering forces using a coupled viscous/potential-flow method for integrated propulsors." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9545.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1999.Includes bibliographical references (leaves 121-126) and index.
This thesis develops a method to analyze the maneuvering forces on surfaced and underwater vehicles with complex propulsors. The analysis method is developed for general propellers yet has unique applicability to model highly contracting stern flows associated with integrated propulsors. Integrated propulsors exhibit strong coupling of the various blade-rows and duct, if present, to the vehicle stern. The method developed herein provides a robust means to analyze propulsor-induced maneuvering forces including those arising from wake-adapted, multi-stage, ducted propulsors. The heart of the maneuvering force prediction is a three-dimensional, unsteady lifting-surface method developed as the first part of this thesis. The new method is designated PUF-14 for Propeller Unsteady Forces. The lifting-surface method uses many advanced techniques. One significant advance is the use of a wake-adapted lattice to model the flow through the propulsor. In related research, a 2-D Kutta condition has been augmented using Lagrangian interpolation to dramatically reduce the required computational time to model a 2-D gust. The second thrust of this thesis couples the unsteady lifting-surface method with a three-dimensional, time-average Reynolds-Averaged Na vier-Stokes flow solver. Rotating a propeller through a spatially-varying flow field causes temporally-varying forces on the propeller. From the converged-coupled solution, the maneuvering and blade rate forces can be estimated. This thesis explores the relationship of time-varying and time-average forces in the flow solver and potential-flow domains. Similarly, it explores the relationship of the effective inflow in the two domains. Finally, this thesis details the synergistic means to correctly couple the potential-flow method to a viscous solver. Verification and validation of the method have been done on a variety of geometries and vehicles. Preliminary results show good correlation with experiment. The results strongly suggest this maneuvering force prediction method has great potential for the modern propulsor designer.
by Christopher L. Warren.
Ph.D.
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Thomas, Mark W. (Mark Wayne). "A Pareto frontier for full stern submarines via genetic algorithm." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9998.
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Zhou, Qing 1964. "Analysis of plane strain necking and fracture in strain hardening materials." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11636.
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Diggs, James Gregory. "A propeller blade design method using generalized geometry and viscous flow computations." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37747.
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Rao, V. N. Rama. "The radiation and vibration of drilling tubulars in fluid-filled boreholes." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/11277.
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Hayner, Mark A. (Mark Andrew). "Optimized finite difference schemes for wave propagation in high loss viscoelastic material." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36488.
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Göktuğ, Gökhan. "Real-time non-contact measurement and analysis for the control of distortion during welding." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37748.
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Johnson, Mark Edward Massachusetts Institute of Technology. "The joint modular intermodal container : is this the future of naval logistics?" Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33567.
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Thesis (S.M. in Naval Architecture and Marine Engineering; and, S.M. in Ocean Systems Management)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2005.Includes bibliographical references (p. 109-113).
Under the fiscal reality of the 21st century military budget, the typically manpower intensive United States Navy has had to learn to do more with less of everything, in many cases specifically less sailors. One mission area that is prime for manpower reduction is naval logistics. JMIC, the Joint Military Intermodal Container is a combined Naval Sea Systems Command/ Office of the Chief of Naval Operations (NAVSEA/OPNAV) program that is designed to change the way the United States Navy conducts logistics. Automation and efficiency improvements inherent to the JMIC program are proposed to drastically lower the manpower requirements and complexity of the US Navy logistics pipeline. JMIC is a program in the very early stages of development. This thesis will examine some of the operational and technical challenges associated with incorporating JMIC into the United States Navy, and ultimately United States Military logistics architecture.
by Mark Edward Johnson.
S.M.in Naval Architecture and Marine Engineering; and, S.M.in Ocean Systems Management