Thèses sur le sujet « Mechanic (Ship) »
Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Mechanic (Ship).
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleures thèses pour votre recherche sur le sujet « Mechanic (Ship) ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les thèses sur diverses disciplines et organisez correctement votre bibliographie.
1
Avgouleas, Kyriakos. « Optimal ship routing ». Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44861.
Texte intégralRésumé :
Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 114-118).
Fuel savings in ship navigation has always been a popular subject in the maritime industry as well as the world's largest Navies. Oil prices and environmental considerations drive the effort for more fuel-efficient navigation. This thesis addresses the problem of deterministic minimum fuel routing by applying optimal control theory in conjunction with state of the art hydrodynamic and weather forecasting tools. A fictitious trans-Atlantic route is established and the optimal combination of speed and heading is determined, so that fuel consumption is minimized while certain safety constraints are met. The safety constraints are defined as the probabilities of slamming and deck wetness, both of which are not allowed to exceed prescribed limiting values. The problem formulation adopted in the thesis lies in the framework of Dynamic Programming, which is most suitable for computer implementation. The hydrodynamic performance of the ship is computed through the use of SWAN1, an advanced frequency domain CFD code. With the aid of SWAN1, ship motions and resistance can be accurately calculated. The latter includes the estimation of mean added resistance in waves, which has a major effect on the fuel consumption of ships sailing in rough seas. Wave and swell forecasts are provided in a deterministic setting by a third generation numerical wave model, the WAM cycle 4, developed at the European Center for Medium-Range Weather Forecasts (ECMWF). Utilizing the hydrodynamic results and the output of the wave model a computer program is developed in MATLAB®, which employs the Iterative Dynamic Programming algorithm to solve the optimal control problem.
by Kyriakos Avgouleas.
Nav.E.and S.M.
2
Pêgo, João Pedro Gomes Moreira. « Advanced fluid mechanics studies of ship propulsion systems ». [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=983754853.
Texte intégral
3
Miroyannis, Aristides. « Estimation of ship construction costs ». Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36275.
Texte intégralRésumé :
Thesis (S.M. in Ocean Systems Management)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 105-107).
Since the end of the Cold War naval procurement for the US Navy has seen a dramatic decrease. This decrease in defense spending has placed existing programs under more scrutiny than previous years. As a result there is less tolerance on the part of taxpayers and Congress for procurement cost growth. This Thesis attempts to examine the current method that the Navy conducts ship cost estimates and suggests changes in order to improve the confidence level and accuracy of the forecasts. An examination of how industry is conducting cost estimates was used as a comparison to the current Navy practices. Finally using only a weight based approach to ship cost estimating is insufficient. It is necessary to develop and use a model that incorporates other cost driving factors in order to develop estimates of sufficient quality at the preliminary design level.
by Aristides Miroyannis.
S.M.in Ocean Systems Management
4
Thomas, Paul Francis. « The mechanics of plate cutting with application to ship grounding ». Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12839.
Texte intégralRésumé :
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1992 and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1992.Includes bibliographical references (leaves 160-163).
by Paul Francis Thomas.
M.S.
5
Voxakis, Petros. « Ship hull resistance calculations using CFD methods ». Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74895.
Texte intégralRésumé :
Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77-78).
In past years, the computational power and run-time required by Computational Fluid Dynamics (CFD) codes restricted their use in ship design space exploration. Increases in computational power available to designers, in addition to more efficient codes, have made CFD a valuable tool for early stage ship design and trade studies. In this work an existing physical model (DTMB #5415, similar to the US Navy DDG-51 combatant) was replicated in STAR-CCM+, initially without appendages, then with the addition of the appendages. Towed resistance was calculated at various speeds. The bare hull model was unconstrained in heave and pitch, thus allowing the simulation to achieve steady dynamic attitude for each speed run. The effect of dynamic attitude on the resistance is considered to be significant and requires accurate prediction. The results were validated by comparison to available data from tow tank tests of the physical model. The results demonstrate the accuracy of the CFD package and the potential for increasing the use of CFD as an effective tool in design space exploration. This will significantly reduce the time and cost of studies that previously depended solely on physical model testing during preliminary ship design efforts.
by Petros Voxakis.
Nav.E.and S.M.
6
Sievenpiper, Bartholomew J. (Bartholomew Jay). « Electrical ship demand modeling for future generation warships ». Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81589.
Texte intégralRésumé :
Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 98-99).
The design of future warships will require increased reliance on accurate prediction of electrical demand as the shipboard consumption continues to rise. Current US Navy policy, codified in design standards, dictates methods of calculating the average demand power. Using several modern sources of information for the DDG-51 class ship, this thesis investigates the utility of current analysis techniques and examines possible improvements. This thesis expands upon a basic method of modeling and simulation to develop a design tool that would provide an improved method of predicting ship electrical loads with increased fidelity of the ship's electrical demand. These efforts ultimately allow a better understanding of ship behavior to enable decision making in all stages of Navy ship design.
by Bartholomew J. Sievenpiper.
Nav.E.and S.M.
7
Katsoufis, George P. (George Paraskevas). « A decision making framework for cruise ship design ». Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35707.
Texte intégralRésumé :
Thesis (S.M. in Ocean Systems Management and S.M. in Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 91-97).
This thesis develops a new decision making framework for initial cruise ship design. Through review of effectiveness analysis and multi-criteria decision making, a uniform philosophy is created to articulate a framework that would enable a designer to more accurately assess what design alternatives are more important than others and how their changes affect the overall system being designed. Through a brief historical account, top-level Measures of Merit are developed and used with the framework and then applied to a requirements and effectiveness case study on initial concept development of a cruise ship. This is performed using Response Surface Methods to enable the user to visualize the design space as well as interact with it; the results and methods to visualize the design space are discussed. Finally, a Unified Tradeoff Environment is discussed, a framework that pools the aforementioned requirements and effectiveness analysis with design and technology forecasting to enable the user to make better informed requirements derivation and design selection.
by George P. Katsoufis.
S.M.in Ocean Systems Management and S.M.in Naval Architecture and Marine Engineering
8
Leghorn, Jeremy T. (Jeremy Thomas). « Modeling for ship power system emulation ». Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50590.
Texte intégralRésumé :
Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Includes bibliographical references (p. 68).
With the U.S. Navy's continued focus on Integrated Fight Thru Power (IFTP) there has been an ever increasing effort to ensure an electrical distribution system that maintains maximum capabilities in the event of system faults. This is to ensure that the crew has the ability to complete real time tactical missions in the event of battle damage to any localized portions of the electrical distribution system. Fault isolation is a priority component of the U.S. Navy's Next Generation Integrated Power System (NGIPS) Roadmap, which lays out the framework as well as milestone dates for future development. Non-Intrusive Load Monitoring (NILM), which has been used extensively for condition based maintenance applications, could simultaneously be used to enhance the existing zonal protection system employed with Multi-Function Monitors (MFM). NILM may be able to, inexpensively, use the existing current and voltage sensors available from the MFM hardware to determine electrical loading which could allow for faster fault isolation capability. A test platform with three 5000 watt synchronous generators is being constructed to emulate a U.S. Navy DDG 51 FLT IIA class ship electric plant. This is being accomplished in order to evaluate the feasibility of improving the fault isolation capabilities of the MFM with NILM implementation. The first step in this endeavor will be to electrically relate the test platform to the DDG electric plant. In order to accomplish this step, the fault simulation results from the test platform will be compared to simulated faults using U.S. Navy data from DDG 51 electric plants.
(cont.) This will allow for the fault isolation results from the test platform to be related to the DDG 51 electric plant.
by Jeremy T. Leghorn.
S.M.
Nav.E.
9
Tober, Hampus. « Evaluation of drag estimation methods for ship hulls ». Thesis, KTH, Mekanik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277843.
Texte intégralRésumé :
This study aims to evaluate to which degree CFD can complement traditional towing-tank experiments, and to develop a computationally cheap and robust methodology for these type of simulations. Two radically different surface ship hulls were chosen for the trials: a capesize bulk carrier and a fast displacement hull. A bare submarine hull was also used to benchmark the software in the early stages of the study. All simulations were Reynolds–Averaged Navier–Stokes (RANS) simulations using the k-w-SST turbulence model. The chosen software was OpenFOAM 5.x and foam-extend 4.1 coupled with the commercial expansion Naval Hydro Pack, which is supposed to handle high Courant numbers well. Producing a high-quality mesh which is able to capture both the free surface and the boundary layers proved to be of utmost importance and the meshing procedure is thus discussed in detail. A majority of the surface ship simulations suffered from a phenomenon known as numerical ventilation. The effect seemed to be much worse for the fast-displacement hull and the drag estimates for this hull deviated around 16.1% from experimental data. The bulk carrier was less affected and the drag estimates for this hull only deviated around 6.3% from experimental data. In order to reduce the computational cost, all surface ship simulations were run with a maximum Courant number of 25 and some consequences of this are also discussed.
10
Jahnke, Joshua James. « Hydrostatic and intact stability analysis for a surface ship ». Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/58868.
Texte intégralRésumé :
Thesis (S.M. in Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 53).
Ship's lines are designed such that they are fair. To the naval architect, fairness means that the lines exhibit a continuous second derivative. This is the definition of a spline. Before the advent of digital computers, naval architects checked every line on a lines plan for fairness by bending a thin stick of wood, called a batten, on the line. If the line followed the natural bend of the batten, the line was fair. This phenomenon follows from the beam equation, which shows that the minimum energy in the beam occurs when the beam has a continuous second derivative of position. Hydrostatics lies at the heart of naval architecture. The hydrostatic properties of a hull are determined by the lines and their interpretation using rules of integration. The resulting analysis is presented in the form of graphs, termed the "curves of form" or "displacement and other curves." An intact stability analysis follows naturally from the hydrostatic analysis. Hydrostatics (determination of KM) coupled with a KG value can be used to predict initial stability. This intact stability analysis evaluates the range of stability at both small and large angles of inclination. The responses of the hull to static and dynamic loading situations can be inferred from the curves of form. Their most basic use is to determine the static waterline in various loading scenarios. A more subtle use is to determine the correct placement of the vertical center of gravity to ensure a sea kindly roll period, stability in beam winds, and stability in high speed turns. Various computational tools can be used to compute the hydrostatic and stability properties of a ship. This thesis explores the results from two computer aided design tools used by the U.S. Navy and commercial industry; Advanced Surface Ship and Submarine Evaluation Tool (ASSET) and Program for Operational Ship Salvage Engineering (POSSE).
by Joshua James Jahnke.
S.M.in Naval Architecture and Marine Engineering
11
Johnson, Brian (Brian David). « Resistance and wake prediction for early stage ship design ». Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/85527.
Texte intégralRésumé :
Thesis: S.M. in Naval Architecture and Marine Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 75-76).
Before the detailed design of a new vessel a designer would like to explore the design space to identify an appropriate starting point for the concept design. The base design needs to be done at the preliminary design level with codes that execute fast to completely explore the design space. The intent of this thesis is to produce a preliminary design tool that will allow the designer to predict the total resistance and propeller wake for use in an optimization program, having total propulsive efficiency as an objective function. There exist design tools to predict the total resistance and propeller wake, but none that provide adequate computational times for the preliminary design stage. The tool developed uses a potential flow solution coupled with an integral boundary layer solver to predict the viscous resistance and propeller wake. The wave drag is calculated using a modified linear theory, thus eliminating the need to run fully three-dimensional free surface CFD codes. The tool developed is validated against published Series 60 test data.
by Brian Johnson.
S.M. in Naval Architecture and Marine Engineering
12
Tratch, Jorge. « Vibration transmission through machinery foundation and ship bottom structure ». Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15216.
Texte intégralRésumé :
Thesis (Mech.E)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Includes bibliographical references.
by Jorge Tratch Junior.
Mech.E
13
Kokko, Michael A. (Michael Andrew). « Range-based navigation of AUVs operating near ship hulls ». Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40292.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.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. 107-109).
In-water ship hull inspection is essential for both routine preventative maintenance as well as for timely detection and neutralization of limpet mines planted on military and commercial vessels. While a host of inspection methods have been proposed for this task, Autonomous Underwater Vehicles (AUVs) are particularly well-suited for such missions as they require neither constant human supervision nor a restrictive tether as do Remotely Operated Vehicles (ROVs). MIT and Bluefin Robotics have jointly developed a Hovering AUV (HAUV) for the inspection of ship hulls and other submerged marine structures which has been successfully demonstrated to achieve a coverage rate on the order of 700m2/hour with centimeter-scale resolution for a variety of hull types. AUV navigation often involves dead reckoning based on velocity measurements from an acoustic Doppler Velocity Log (DVL) sensor. As this strategy is inherently susceptible to drift, related efforts seek to generate vehicle position updates through either Simultaneous Localization and Mapping (SLAM) or the use of external sensor networks. In this work we propose a unique localization approach which relies on range measurements taken to surfaces of known curvature.
(cont.) The algorithm is developed for navigating relative to simple parabolic curvatures and is tested both in simulation and on a floating raft robot. Localization and servoing are demonstrated in real-time to achieve estimated position deviations within millimeters of their expected values. In addition to exploring other facets of hull-relative navigation, this thesis also documents a significant mechanical redesign of certain HAUV components.
by Michael A. Kokko.
S.M.
14
Trost, Christopher S. (Christopher Stone). « Framework for systematic evaluation of environmental ship design ». Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43457.
Texte intégralRésumé :
Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1997, and Thesis (M. Eng)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997.Includes bibliographical references (leaves 104-107).
by Christopher S. Trost.
M.Eng
Nav.E.
15
Stevens, Kevin Wilson. « Adaptive sequential sampling for extreme event statistics in ship design ». Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118693.
Texte intégralRésumé :
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Thesis: S.M. in Naval Architecture and Marine Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 103-105).
For more than a century, many facets of ship design have fallen into the domain of rules-based engineering. Recent technological progress has been validated to the point that many of these areas will soon warrant reconsideration. In this emerging environment, accurately predicting the motions and loading conditions which a ship is likely to encounter during its lifetime takes on renewed importance. Even when the wave elevations a ship encounters are governed by normal (Gaussian) statistics, the resulting motions and loading conditions can deviate substantially due to the nonlinear nature of the ship dynamics. This is sometimes manifested by heavy tailed non-Gaussian statistics in which extreme events have a high probability of occurrence. The primary method for quantifying these extreme events is to perform direct Monte-Carlo simulations of a desired seaway and tabulate the results. While this method has been shown to be largely accurate, it is computationally expensive and in many cases impractical; today's computers and software packages can only perform these analyses slightly faster than real time, making it unlikely that they will accurately capture the 500 or 1,000-year wave or wave group even if run in parallel on a large computer cluster; these statistics are instead extrapolated. Recent work by Mohamad and Sapsis at the MIT Stochastic Analysis and Non- Linear Dynamics (SAND) lab has identified a new approach for quantifying generic extreme events of systems subjected to irregular waves and coupled it with a sequential sampling algorithm which allows the accurate results to be determined for meager computational cost. This thesis discusses the results of applying this approach directly to ship motions and loading conditions using a modified version of the Large Amplitude Motions Program (LAMP) software package. By simulating the ship response for a small number of wave-groups (order of 100) we assess the accuracy of the method to capture the tail structure of the probability distribution function in different cases and for different observables. Results are compared with direct Monte-Carlo simulations.
by Kevin Wilson Stevens.
S.M.
S.M. in Naval Architecture and Marine Engineering
16
Gilligan, Brian Kenneth. « Electric ship digital twin : framework for cyber-physical system security ». Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122264.
Texte intégralRésumé :
Thesis: S.M. in Naval Architecture and Marine Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 90-95).
This thesis presents a dynamic model that can be used for a digital twin of an electric ship. The model is an end-to-end simulation of a ship from prime mover to maneuvering, seakeeping, and propeller ventilation in random waves representing the behavior of a physical ship. There is a trend towards increasingly networked sensors and actuators to enable condition monitoring, ensure efficient operation, and allow for autonomy. However, a cyberattack on a networked control system presents not just the possibility of information theft but of physical system damage and loss of control. Thus, a detection scheme is proposed for cyber-physical systems using a joint unscented Kalman filter. It is employed to detect cyberattacks in the simulation model of an electric ship including sensor attacks and controller attacks on a gas turbine, synchronous generator, and automatic heading control. Finally, a system theoretic framework is presented for optimal sensor placement to minimize cyber vulnerability.
United States. Office of Naval Researchgrant N00014-16-1- 2956
by Brian Kenneth Gilligan.
S.M. in Naval Architecture and Marine Engineering
S.M.inNavalArchitectureandMarineEngineering Massachusetts Institute of Technology, Department of Mechanical Engineering
17
Morton, Casey John 1969. « The application of advanced hydrodynamic analyses in ship design ». Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47676.
Texte intégralRésumé :
Thesis (Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.Includes bibliographical references (p. 219-221).
Recent advances in computational hydrodynamics offer the opportunity to incorporate more accurate analyses earlier in the ship design process. In particular, significant work has been conducted towards the prediction of nonlinear wave-induced motions and loads in the time domain. Seakeeping analysis has traditionally been incorporated late in the design process, using parametrics and two-dimensional linear strip theory methods in the frequency domain. Model testing, due to its relative expense, is incorporated even later in the process. As a result, seakeeping performance is often evaluated after, rather than during, each stage of ship design. Serious problems, particularly in structural loading, may not be discovered until late in the process. This research investigates the applicability of nonlinear time domain predictions to ship design. A method for incorporating time domain analyses of motions and loads in early design is proposed. Several hulls are tested in the frequency and time domains in moderate to severe seas. The first set of hulls are mathematically defined, derived from the well-known Wigley Seakeeping Hull, with variations in flare, tumblehome, and waterline entrance both above and below the calm waterline. A Very Large Crude Carrier, representative of many commercial hulls, is also analyzed. The nonlinear motions and loads differ substantially from linear predictions, especially in critical operating conditions. The nonlinear methods also predict significant variations in performance due to flare and tumblehome, which are not adequately observed with linear theory. Despite increased preparation complexity and computation times, and requirements for validation, time domain methods should be incorporated in early design. Detailed analyses of hull concepts may then be conducted much sooner, reducing the economic and schedule impact of any necessary changes.
by Casey John Morton.
M.S.
Nav.E.
18
Yang, Park Dal Chi. « Energy absorption and collapse of ship structures with particular reference to collisions ». Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339754.
Texte intégral
19
Ucar, Hakan. « Dynamic response of a catamaran-hull ship subjected to underwater explosions ». Thesis, Monterey, Calif. : Naval Postgraduate School, 2006. http://bosun.nps.edu/uhtbin/hyperion.exe/06Dec%5FUcar.pdf.
Texte intégralRésumé :
Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 2006.Thesis Advisor(s): Young S. Shin, Jarema M. Didoszak. "December 2006." Includes bibliographical references (p. 137-138). Also available in print.
20
Schmitt, Kyle (Kyle P. ). « Modeling and simulation of an all electric ship in random seas ». Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62537.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 126-132).
This Masters thesis, conducted in support of the All Electric Ship (AES) early design effort, presents two computational programs for analysis and simulation: a full-scale, end-to-end AES simulator and an analytical performance and stability assessment tool for the ship's propulsion drive; the integrated power system (IPS). The AES simulator incorporates high order techniques for the hull modeling with low order, low effort models for the propellers, IPS, and prime movers, culminating in a fully-coupled, end-to-end, simulation environment, which is still practical for high effort studies like uncertainty quantification or optimization. The most appealing characteristic of this program is the time domain hull model with combines nonlinear maneuvering equations, seakeeping equations, and second order wave force equations. This allows for the prediction of propeller elevation and inflow velocity in random seas, and effectively the high fidelity modeling of propeller load schedules. This capability is vital for AES design where propeller load fluctuations can lead to large electrical power transients onboard. To demonstrate the capability of the AES simulator, ship trails are run in calm and random seas. IPS state evolutions are given to show the propagation of load disturbances. Monte Carlo methods are applied to assess transients in the inherently random sea environment. The IPS assessment tool attempts analytical quantification of the performance and stability of the Purdue MVDC Testbed, a scaled IPS composed of analagous elements: electric machinery, power converters, MVDC distribution, and bus voltage/induction motor torque control schemes. The thesis details the applicable nonlinear equations and the tools for identifying system equilibrium points. Then, small displacement theory is used to attain linear state space matrices valid near the operating points, from which traditional stability and performance techniques can be applied. Methods for closed loop analysis are suggested including ways to assess the hysteretic control elements used for induction motor torque control. Results from experiments with the high fidelity, high effort, Purude MVDC Testbed model are used for validation.
by Kyle Schmitt.
S.M.
21
Gheriani, Eran (Eran Y. ). « Fuel consumption prediction methodology for early stages of naval ship design ». Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/70435.
Texte intégralRésumé :
Thesis (S.M. in Mechanical Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M. in Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 72).
In recent years, fuel consumption has increased in importance as a design parameter in Navy ships. Economical fuel consumption is important not only for operating cost measures but also for ship endurance tankage requirements. Minimizing fuel consumption has many benefits for both naval and commercial ships. This thesis work will suggest a new comprehensive approach to early-stage ship design to determine fuel consumption for the whole system. A hull must be designed to work harmoniously with an optimized propulsor and propulsion plant to ensure best performance and to comply with imposed design requirements. Thus, this work will address three main aspects of the fuel consumption equation: -- Ship's resistance is calculated using a computational fluid dynamics simulation of the vessel in calm water at various speeds up to maximum speed. -- Propeller performance is based on propeller curves for the chosen propulsor. -- Efficiencies of the drive train and electrical production and distribution system are calculated for all operating conditions. Note that for an electric-drive ship, the non-propulsion electrical loads must be included in the calculations. These three major components of the ship efficiency equation are assessed for each speed and battle condition of the mission profile. In addition, the corresponding operating conditions for each piece of machinery will be specified to estimate the total fuel consumption and tankage required. In this thesis work, I will suggest a design methodology to determine hull resistance and total power for a given ship with a specified operational profile. The total power for the operational profile will be translated to fuel consumption, thus producing annual fuel consumption requirements and recommended tankage to support the operational needs.
by Eran Gheriani.
S.M.in Naval Architecture and Marine Engineering
S.M.in Mechanical Engineering
22
Underwood, J. « Strength assessment of damaged steel ship structures ». Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/355704/.
Texte intégralRésumé :
In 2012 106 vessels over 100 gross tonnes were lost. During the damage incidents many of these vessels required assistance from shore based emergency response services with regards to their damaged strength to stabilise the situation, preserve life, prevent environmental disaster and limit financial costs to owners and insurers. The research work presented in this Engineering Doctorate Thesis surrounds the strength assessment of damaged steel ship structures, the influence of damage on the strength of steel-plated structures and methods for assessing the residual strength of a vessel in an emergency. The focus of the work is to improve the modelling of damaged steel ship structures within an emergency situation, in order to improve guidance provided to a stricken vessel during a damage incident or salvage process. Literature study has shown that structural idealisation through the use of interframe progressive collapse analysis, to be the current state of the art method for the rapid assessment of intact and damaged ship structures. However, a number of weaknesses have been identified in the method when applied to damage assessment. The literature study has also shown a lack of understanding of the effect of damage on steel-plated structures as specific analysis has not been performed previously. Significant research has been undertaken into the influence of damage, in the form of a hole, on the ultimate collapse strength of steel-plated structures. Three levels of structural modelling have been used, stiffened-plate, stiffened panel and grillage. Comparison of the predicted ultimate collapse strength by finite element analysis (FEA) with predictions using the interframe progressive collapse idealisation, has shown the calculated results to be conservative for the assessment of damaged structure when the failure mode remains in the interframe collapse form. However, changes in the failure mode lead to the interframe progressive collapse method over predicting the ultimate collapse strength. The analysis shows that even small damage events can lead to significant changes to the failure mode and resulting ultimate collapse strength of the structure. Such influences must be accounted for in any simplified method. A new method for the assessment of damaged ship structures is proposed that is capable of modelling a damage scenario more accurately. Demonstration of the method has shown the results to be less conservative than the current state of the art, when compared to FEA, for local analysis of damaged steel-plated structure. The ability of the method to account for the influence of damage, and the resulting failure modes, that may significantly influence the ultimate bending strength of the structure has also been demonstrated. The method implements a compartment level progressive collapse analysis with structural data captured through the use of the response surface method ‘kriging’, using data points provided from FEA. This method allows the critical damage variables to be captured and strength data accessible quickly for use in the analysis. The time to provide a solution to the damage scenario is equivalent to the existing interframe progressive collapse method. Therefore, the method is suitable for application within an emergency response or salvage service.
23
Surko, Stephen William 1960. « The residual strength of a ship after an internal explosion ». Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/33476.
Texte intégralRésumé :
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1988, and (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1988.Includes bibliographical references.
Support provided by the Office of Naval Research.
by Stephen William Surko.
M.S.
24
Thomas, Brian S. S. M. Massachusetts Institute of Technology. « Optimal control theory applied to ship maneuvering in restricted waters ». Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33591.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaves 70-71).
Ship drivers have long understood that powerful interaction forces exist when ships operate in close proximity to rigid boundaries or other vessels. Controlling the effects of these forces has been traditionally handled by experienced helmsmen. The purpose of this research is to apply modern optimal control theory to these maneuvering scenarios in order to show that helmsman may some day be replaced by modern controllers. The maneuvering equations of motion are cast in a linear state space framework, permitting the design of a linear quadratic (LQ) controller. In addition, the hydrodynamic effects are modeled using potential flow theory in order to simulate the interaction forces and test the efficacy of the controller. This research demonstrates that the linear quadratic regulator effectively controls ship motions due to the presence of a boundary or other vessel over a broad range of speeds and separation distances. Furthermore, the method proposed provides stable control in the presence of additional. stochastic disturbances.
by Brian S. Thomas.
S.M.
25
Weaver, M. Cameron (Myron Cameron) 1962. « Ship hull plating weld misalignment effects when subjected to tension ». Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/91335.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (leaf 43).
by M. Cameron Weaver.
S.M.
26
Dooley, Gregory M. « Ship airwakes in waves and motions and effects on helicopter operation ». Thesis, University of Iowa, 2019. https://ir.uiowa.edu/etd/6727.
Texte intégralRésumé :
This thesis focuses on the effects of wave-induced motions on the airwake of a ship and on the operation of a helicopter in the airwake. While the topic is broad, efforts are concentrated on understanding fundamentals of the ship’s airwake structure at varying Reynolds (Re) numbers without motions, using available experimental data for validation of the computational fluid dynamics (CFD) methodology used, and on studying the effects of waves and motions on the airwake of a ship and a helicopter operating above a ship’s flight deck in full-scale. The static ONR Tumblehome (ONRT) ship geometry with a solid boundary representative of the free surface is simulated at three different Re numbers, 3.2x104, 1x106, and 1.3x108. Validation is performed against experimental measurements at model-scale Re=1x106. Full-scale simulations of the ONRT are carried out in head winds and regular waves approximately equivalent to conditions seen at sea states 3 and 6. Effects of waves and motions are isolated for both sea states using simulations with combinations of waves and motions, waves and no motions, no waves with motions, and no motions or waves. A triple velocity decomposition is conducted in order to quantify changes in the airwake due to motions and waves. The operation of rotorcraft in the ONRT airwake is analyzed using one-way and two-way coupling approaches. The one-way coupling approach uses the velocity field data from the full-scale ONRT simulations and disk actuator theory to calculate thrust fluctuations for three different rotor sizes. The results of the one-way coupling approach show that the smallest rotor is much more affected by small scale turbulence, while small scale fluctuations are filtered out by larger rotor diameters. In the two-way coupling approach, a helicopter based on the Sikorsky SH-60 hovering above the flight deck is simulated, including explicitly moving grids to discretize the main rotor, tail rotor, and fuselage. This method captures the effects of the interaction between the rotor downwash and the ONRT airwake. The study shows that for the mild conditions of sea state 3 the motions have little effect on the airwake behavior. At sea state 6 the airwake behavior is significantly altered, which is reflected in the resulting forces on the helicopter body operating in this condition.
27
Seo, S. G. « The calculation of potential flow around and in the wake of a surface ship ». Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370641.
Texte intégral
28
Olena, Jessica Jill. « Design, evaluation, and validation of a naval ship structural health monitoring tool ». Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111892.
Texte intégralRésumé :
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 123-125).
The US Navy implements structural preventative maintenance procedures onboard its vessels using ship's personnel inspection. These procedures have been largely successful in identifying major problem areas before any interference with mission execution has occurred. However, changes in the Navy's manning philosophy to minimal manning and new ship designs focused on automation encourage a re-evaluation of these structural preventative maintenance procedures. Automation of structural inspection and damage detection would reduce associated manpower costs as well as inform better preventative maintenance schedules for US Navy vessels. This study outlines a modeling tool for structural health monitoring using nonlinear Kalman Filter methodologies such as the Extended Kalman Filter and the Ensemble Kalman Filter to identify damage within a structural model. Through the observation of structural responses and the formulation of a Kalman Filter, it is possible to produce estimates of structural parameters related to damage, specifically changes to elastic modulus and changes in material density. The results of this modeling tool were evaluated to quantify the time and length scales required for damage detection and were validated against a structural model generated in the MAESTRO Global Structural Analysis software suite.
by Jessica Jill Olena.
Nav. E.
S.M.
29
Ulusoy, Talha. « State-space modeling and optimal control of ship motions in a seastate ». Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37272.
Texte intégralRésumé :
Thesis (Ph. D. in Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 98-101).
In this thesis, a new state-space model and motion control algorithm are developed from first principles for the improvement of the seakeeping performance of high-speed vessels equipped with lifting appendages that are actively controlled in regular and random waves. A ship at sea can experience all the translational and rotational modes of motion that are undesirable, yet unavoidable. These motions have been of great concern to the navies and other organizations engaged in shipping for decades and need to be dealt with through the use of a control system. In this work, a new general purpose state-space control-oriented time domain model for the ship motions is introduced. A discrete auto-regressive state-space model is developed using the state-of-the-art linear seakeeping simulation method SWAN. Novel features of this state-space model are its ability to capture all free-surface memory effects present in the seakeeping problem, its coupling with the theoretical framework of Linear Quadratic (LQ) controllers and its efficient implementation.
(cont.) The development from first principles of a reliable ship motion control simulation method based on SWAN and its coupling with LQ controllers used to actively regulate the angle of attack of lifting appendages, circumvents the need to perform sea trials or model experiments that are harder, time-consuming and expensive to carry out. The performance of the method is illustrated for a catamaran vessel fitted with bow and stern hydrofoils. Simulations of the vessel motions were performed with and without the effect of the controller in regular and random waves. It is concluded that the combination of the proposed state-space model with the LQ controller was very effective in reducing the undesired motions of the vessel in waves over a wide range of wave frequencies and ship speeds.
by Talha Ulusoy.
Ph.D.in Naval Architecture and Marine Engineering
30
Jones, Adam T. (Adam Thomas). « Design space exploration and optimization using modern ship design tools ». Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92124.
Texte intégralRésumé :
Thesis: S.M., Massachusetts Institute of Technology, Engineering Systems Division, 2014.Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 163-164).
Modern Naval Architects use a variety of computer design tools to explore feasible options for clean sheet ship designs. Under the Naval Sea Systems Command (NAVSEA), the Naval Surface Warfare Center, Carderock Division (NSWCCD) has created computer tools for ship design and analysis purposes. This paper presents an overview of some of these tools, specifically the Advanced Ship and Submarine Evaluation Tool (ASSET) version 6.3 and the Integrated Hull Design Environment (IHDE). This paper provides a detailed explanation of a ship design using these advanced tools and presents methods for optimizing the performance of the hullform, the selection of engines for fuel efficiency, and the loading of engines for fuel efficiency. The detailed ship design explores the design space given a set of specific requirements for a cruiser-type naval vessel. The hullform optimization technique reduces a ships residual resistance by using both ASSET and IHDE in a Design of Experiments (DoE) approach to reaching an optimum solution. The paper will provide a detailed example resulting in a 12% reduction in total ship drag by implementing this technique on a previously designed hullform. The reduction of drag results in a proportional reduction in the amount of fuel used to push the ship through the water. The engine selection optimization technique uses MATLAB to calculate the ideal engines to use for fuel minimization. For a given speed-time or power-time profile, the code will evaluate hundreds of combinations of engines and provide the optimum engine combination and engine loading for minimizing the total fuel consumption. This optimization has the potential to reduce fuel consumption of current naval warships by upwards of 30%.
by Adam T. Jones.
S.M.
Nav. E.
31
Stergiakis, Constantinos L. « Design impact of propulsion plant variations on a small combatant ship ». Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14390.
Texte intégralRésumé :
Thesis (Ocean E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1988, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1988.Includes bibliographical references.
by Constantinos L. Stergiakis.
M.S.
Ocean E.
32
Price, Shelly L. (Shelly Loustaunau) 1974. « Integrating response surface methods and uncertainty analysis into ship concept exploration ». Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/91361.
Texte intégralRésumé :
Thesis (Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.Includes bibliographical references (p. 60).
by Shelly L. Price.
Nav.E.
S.M.
33
Rathore, Uditbhan S. « Quantification of extreme event statistics in ship design ». Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122613.
Texte intégralRésumé :
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, System Design and Management Program, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 85-86).
Increased operational demands on Navy vessels extend time at sea and service life, making the accurate prediction of catastrophic failures increasingly challenging. The high value of these capital assets puts great pressure on designers and decision-makers as they work towards preventing such failures while balancing both engineering and material cost. The current method for the quantification of extreme events is direct Monte Carlo simulation supplemented by complex statistical models. When such models are not sufficiently bound by physics-based simulation, the noise of statistical uncertainty quickly overpowers the response predictions for rare events. This thesis builds on previous work at the MIT Stochastic Analysis and Non-linear Dynamics (SAND) lab for the quantification of extreme events using wave groups. By separating the event probability from the physics models, we are able to capture rare events in ship motion and loading conditions for a modest computational cost. Improvements to the wave groups methodology ensured the slope and amplitude of the incident waves reflected the waves encountered in a given wave spectrum. The remaining discussion explores the value of a near-real-time risk analysis tools in reference to ship design and ship operations, with unique application to Navy and commercial vessels.
by Uditbhan S. Rathore.
Nav. E.
S.M. in Engineering and Management
Nav.E. Massachusetts Institute of Technology, Department of Mechanical Engineering
S.M.inEngineeringandManagement Massachusetts Institute of Technology, System Design and Management Program
34
Jurkiewicz, David J. (David James). « Modular machinery arrangement and its impact in early-stage naval electric ship design ». Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74922.
Texte intégralRésumé :
Thesis (S.M. in Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 75-77).
Electrical power demands for naval surface combatants are projected to rise with the development of increasingly complex and power intensive combat systems. This trend also coincides with the need of achieving maximum fuel efficiency at both high and low hull speeds. A proposed solution to meet current and future energy needs of conventionally powered naval surface combatants is through the use of an Integrated Power System (IPS), which is seen as the next evolution in naval ship design. Unfortunately, historically-based ship design process models and parametrics cannot accommodate new-concept designs that are not incremental changes to previous practice. Additionally, integrating IPS with the next generation of ship designs is also synonymous with the desire of conducting system-level tradeoffs early within the ship design process. In an effort to enhance the relationship between new-concept designs and historically-based ship design processes, this thesis focuses on a novel approach of incorporating IPS at the earliest stage of the design process as part of assessing system-level tradeoffs early. This thesis describes a methodology for the system design and arrangement of an IPS machinery plant based on an objective of meeting a desired power generation level, effectively introducing a power constraint at the start of the design process. In conjunction with the methodology development, a hierarchical process and design tool for integration with Graphics Research Corporation's (GRC) naval architecture software suite, Paramarine, is also produced to assist in rapid development and evaluation of various IPS arrangements. The result of this process, through several case studies, provides insight into equipment selection philosophy, the initial sizing of the ship's machinery box, and the initial definition of electrical zones. Lastly, the developed tool is also used to aid in the creation of "design banks," allowing the naval architect to manage weight, power, and volume at the beginning of the ship design process; therefore, supporting early system-level tradeoffs for new-concept designs.
by David J. Jurkiewicz.
S.M.
S.M.in Naval Architecture and Marine Engineering
35
Thurkins, Eric J. Jr. « Development of an early stage ship design tool for rapid modeling in Paramarine ». Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74992.
Texte intégralRésumé :
Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 85).
In early-stage ship design, it is helpful to perform preliminary design and analysis on many configurations to assist in developing and narrowing the trade space. This process is further complicated with the increasing interest in concepts that are breaks from previous practice, such as Integrated Power System (IPS) designs, which require initial development to go deeper than historically based parametrics can provide. Paramarine is a ship design and analysis tool which can be used in this early-stage design; however, as with many early-stage design tools, the fleshing out of diverse ideas in Paramarine can be time and resource consuming. In an effort to enable a developer to create early-stage designs with depth significant enough to be meaningful but still general enough to allow the level of flexibility in design required in the early stages of development, this project seeks to develop an Early Stage Ship Design Tool (ESSDT). This ESSDT is a novel interface with which a designer can rapidly develop and alter basic, major design components of a ship from a compiled database of components and gain a rendered model for analysis within the naval design tool Paramarine. By making use of many early-stage parametric and developed calculations and leveraging the use of IPS, this ESSDT automates many of the initial ship's estimates and minutia of design. Utilizing both Excel and Paramarine software, the ESSDT rapidly creates a visual model of a basic naval vessel with primary systems and equipment from relatively few initial user inputs while embodying a depth of user-changeable default settings for more complex and non-standard design efforts. Several case studies were run to show the capability and flexibility of the tool, as well as showing how new powering and mechnical systems can affect the parameters of the ship as a system of systems.
by Eric J. Thurkins Jr.
Nav.E.and S.M.
36
Sarris, Emmanouil. « Naval ship propulsion and electric power systems selection for optimal fuel consumption ». Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68573.
Texte intégralRésumé :
Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M. in Engineering and Management)--Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. [100]-102).
Although propulsion and electric power systems selection is an important part of naval ship design, respective decisions often have to be made without detailed ship knowledge (resistance, propulsors, etc.). Propulsion and electric power systems have always had to satisfy speed and ship-service power requirements. Nowadays, increasing fuel costs are moving such decisions towards more fuel-efficient solutions. Unlike commercial ships, naval ships operate in a variety of speeds and electric loads, making fuel consumption optimization challenging. This thesis develops a flexible decision support tool in Matlab® environment, which identifies the propulsion and ship-service power generation systems configuration that minimizes fuel consumption for any ship based on its operating profile. Mechanical-driven propulsion systems with or without propulsion derived ship-service power generation, separate ship-service systems and integrated power systems are analyzed. Modeling includes hull resistance using the Holtrop-Mennen method requiring only basic hull geometry information, propeller efficiencies using the Wageningen B series and transmission and prime movers fuel efficiencies. Propulsion and ship-service power generation systems configuration is optimized using the genetic algorithm. US Navy's Advanced Surface Ship Evaluation Tool (ASSET) model for the DDG-51 Flight I destroyer was used for modeling validation. Optimal fuel consumption results are compared against the existing configuration for the DDG-51 Flight I destroyer using a representative operating profile.
by Emmanouil Sarris.
S.M.in Engineering and Management
Nav.E.
37
Gray, Weston L. « DC to DC power conversion module for the all-electric ship ». Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68166.
Texte intégralRésumé :
Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 91-92).
The MIT end to end electric ship model is being developed to study competing electric ship designs. This project produced a model of a Power Conversion Module (PCM)- 4, DC-to-DC converter which interfaces with the MIT model. The focus was on the Medium Voltage DC (MVDC) architecture, and therefore, the PCM-4 converts a MVDC bus voltage of 3.3, 6.5 or 10 kVDC to 1 kVDC. The design describes the transient and steady-state behavior, and investigates the naval architecture characteristics. A modular architecture, similar to SatCon Applied Technology's Modular Expandable Power Converters, was selected as the best balance for the wide variation in loads experienced. The model consists of a standard module that can be paralleled internally to provide for a wide range of system power requirements. Naval architecture parameters, such as weight, volume, efficiency, and heat load, were compiled into a parametric format allowing a reasonable approximation of actual weight and volume as a function of rating and efficiency and heat load as a function of loading. All of the parameters were evaluated for dependence on the MVDC bus voltage. Verification of the model was pursued through comparison to available simulations of similar power electronics to ensure that the model provided reasonable time response and shape. Finally, the model met all requirements with the exception of efficiency which was slightly lower than the requirement although several ideas were presented to improve efficiency.
by Weston L. Gray.
S.M.
Nav.E.
38
Bebermeyer, Robert E. 1968. « Experimental study on the effect of misfit and mismatch of ship plating welds ». Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/91360.
Texte intégralRésumé :
Thesis (Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.Includes bibliographical references (leaf 47).
by Robert E. Bebermeyer.
Nav.E.
S.M.
39
Larson, David F. H. « A framework for ship stability in a seastate using the state-space Fokker-Planck method ». Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118706.
Texte intégralRésumé :
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 91-93).
Ships sailing on the ocean have many inherent dangers. One of the most compelling is when they interact with severe stochastic waves, resulting in a loss of stability and adversely affecting their operation. This can result in extreme motions, at the very least making life difficult for crew, to potentially the most catastrophic events capsize, and loss of cargo and life. This compels the need to reliably predict vessel responses to wave interactions in order to aid the decision-making process for operating the ship safely. Despite the advances in computational methods and stochastic hydrodynamic theories to this date, a general framework, capable of handling nonlinear three-dimensional effects, arbitrary wave headings and unconventional hull geometries, is still missing from the engineer's toolbox. This thesis presents a new methodology for modeling the nonlinear responses and stability of a ship in stochastic waves. Invoking the weak-scatterer hypothesis, the radiation and diffraction effects are linearized, computed via a panel method, and cast into a state-space form, aided by applying the ESPRIT algorithm. Strong free surface nonlinearities present in the Froude-Krylov exciting and hydrostatic restoring forces are modeled by Fluid Impulse Theory. In parallel, the ambient seastate is represented by a multidimensional stochastic differential equation (SDE) conforming to a prescribed spectrum. Combining the state-space and seastate models capacitates the study of the nonlinear seakeeping and stability of a ship in a broad range of stationary seastates via stochastic calculus methods. Chief among them is the use of the Fokker-Planck equation (FPE), a deterministic partial differential equation governing the joint probability density function of the states of the SDE. The formulation for a rectangular barge rolling in beam waves is presented, with the approach readily extendable to six-degree-of-freedom responses. By deriving a state-space stochastic differential equation for the states governing the vessel response motions, the joint probability density can be found either by numerical Monte-Carlo simulation of the SDE, or by numerically solving the associated FPE.
by David F.H. Larson.
S.M.
40
Mofidi, Alireza. « Ship maneuvers with discretized propeller and coupled propeller model/CFD ». Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5814.
Texte intégralRésumé :
A high fidelity computational fluid dynamics approach to perform direct simulations of ship maneuvers is presented in this thesis. The approach uses dynamic overset grids with a hierarchy of bodies to enable arbitrary motions between objects, and overcome the difficulties in simulation of the moving rudder and rotating propeller. To better resolve propeller/rudder interaction a Delayed Detached Eddy Simulation turbulence model based on Menter’s SST is used. The methodology was implemented in the general purpose RANS/DES/DDES research code REX, and is applied to the KRISO Container Ship (KCS) with moving rudder and rotating propeller in deep and shallow water. For the first time, a grid study is conducted for the self-propulsion condition for the propeller RPM, thrust, torque and lateral force, and for the roll and pitch motions, using grids of 8.7 (coarse), 24.6 (medium) and 71.3 (fine) million points. A grid study is also performed for the zigzag maneuver evaluating the maximum and minimum values of propeller thrust, torque and lateral force roll, pitch, yaw, roll rate, yaw rate and drift throughout the maneuver. An extensive comparison between predicted motions and forces of the direct simulations and the experimental data collected by Schiffbau-Versuchsanstalt Potsdam GmbH (SVA) and Flanders Hydraulics Research (FHR) are presented.
While the results and comparisons with experimental data show that using direct CFD to compute modified and standard maneuvers with moving rudder and rotating discretized propeller is feasible, computational cost remains an impediment for many practical applications. Coupling a dynamic overset CFD solver with a potential propeller code can dramatically reduce the computational time to perform maneuvering simulations by using one order of magnitude larger time step than direct simulation. This thesis investigates the ability of a coupled CFD/potential propeller code approach to simulate maneuvers in ships, where the rudder is located downstream of the propeller. While the approach has been successfully applied to submarine maneuvers, in which the propeller wake is free of interference, the concept had not been evaluated before for cases where an object (the rudder) is immersed in the wake. The study is performed using the CFD code REX and the propeller code PUF-14. Performance of the coupled REX/PUF-14 approach is first tested studying propeller/rudder interaction, evaluating influence of the propeller/rudder gap size and rudder deflection on propeller performance curves and rudder forces, comparing against DDES simulations with a discretized rotating propeller. A grid study was performed for advance coefficient J=0.6 and a rudder angle δ=20 degrees for a propeller rudder gap of 0.2 times the rudder radius, with the resulting grid uncertainties for propeller thrust and torque coefficients suggesting that the effects of the grid changes are small for the present range of grid sizes. A 15/1 zigzag maneuver for the KCS container ship, in which case the rudder is very close downstream of the propeller, is then analyzed, and compared against discretized propeller simulations and experimental data. Self-propulsion coupled REX/PUF-14 results agree very well with experiments and discretized propeller simulations. Prediction of motions, forces and moments, and mean flow field with the coupled REX/PUF-14 approach are comparable to results obtained with discretized propeller simulations and agree with experiments well, though as implemented the coupled approach is unable to resolve tip vortices and other flow structures that interact with the rudder, potentially affecting prediction of flow separation. It can be concluded that coupled CFD/potential flow propeller approaches are an effective and economical way to perform direct simulation of surface ship maneuvers with CFD.
41
Harris, Corey G. (Corey Gabriel). « Design of a shim for a nanopositioner ». Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59928.
Texte intégralRésumé :
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 37).
The purpose of this thesis is to assist in the development of a low cost nanopositioner by designing a specific component - a shim that is located in the scan tip assembly of the nanopositioner. Nanopositioners must maximize precision to successfully produce features of fewer than 100 nm. The kinematic coupling used to place the tool tip is capable of producing a high level of precision across tool changes, assuming the groove mount is held in place. It is therefore very important to secure the groove mount to prevent dislocation and enhance the viability of nano-scale device fabrication. The shim developed within this thesis serves to secure the groove mount of the kinematic coupling, which was previously held in place solely with magnetic attraction. The shim secures the groove mount by applying a force to the side of the groove mount in addition to increasing the magnetic attraction between the groove mount and universal mount of the nanopositioner. It was first modeled with solid and magnetic modeling software before being manufactured and tested. With the addition of the shim, the vertical force required to displace the groove mount increased by a factor of 9.4, from 0.14 N to 1.29 N. Similarly the lateral force increased by a factor of 27.9, from 0.09 N to 2.45 N. As a result, the nanopositioner is significantly better suited to perform its function. The nanopositioner will be used to produce nano-scale devices including carbon nanotubes, molecular actuators, and transistors, with applications across several disciplines. Future work includes developing a tool to bend the shim tabs and simplify the manufacturing process.
by Corey G. Harris.
S.B.
42
Genzman, Grant Norman. « Ship collision and the Offshore Floating Nuclear Plant (OFNP) : analysis of possible threats and security measures ». Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104144.
Texte intégralRésumé :
Thesis: S.M., 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 135-137).
The OFNP research group in the Nuclear Science and Engineering Department at MIT is developing a power plant that combines two well-established technologies -- light water reactors and offshore platforms -- into a new design called the Offshore Floating Nuclear Plant (OFNP). Deploying a nuclear reactor aboard a floating platform up to 12 nautical miles into the ocean raises unique security questions and considerations. This investigation presents a framework for analyzing the threat of intentional ship collision, modeling damage and characterizing the effectiveness of potential solutions, as well as integrating or adapting the recommended security strategies into existing regulatory and legal environments. First, a collision risk assessment is completed and a postulated design-basis collision threat (DBT) is determined to be a 150,000 DWT ship. Next, using the DBT characteristics and the finite element modeling software ABAQUS, estimations for damage are provided for a reference case and for cases with variations in collision characteristics. Results indicate increased ship penetration from faster and larger ships, wedge-shaped ship hulls, fixed OFNP moorings, direct broadside collisions, and OFNP designs with less internal structural support. Additionally, in order to minimize risk of unacceptable damage, the results indicate that vessels larger than 70,000 DWT should be restricted from entering within an eight-nautical mile exclusion zone. The results from the previous assessments are then used to present technical, operational, and regulatory recommendations for damage mitigation. The analysis concludes with an assessment of the existing regulatory and legal environments in which the regulatory solutions would have to be implemented, provides an analysis of the degree to which the ideal regulations comply with existing laws, and then culminates with the presentation of further recommendations and a regulatory strategy framework for meeting security goals while achieving legal compliance. In summary, this investigation considers the threat of intentional collision with an Offshore Floating Nuclear Plant and utilizes risk assessment techniques, numerical modeling, and legal research to contextualize the threat, model possible damage, and present technical, operational, and regulatory solutions for avoiding or mitigating damage.
by Grant Norman Genzman.
S.M.
43
Morgan, Harith. « Design of a mechanism to increase lateral force resistance of an autonomous ship hull cleaning robot ». Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127897.
Texte intégralRésumé :
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (page 27).
Marine biofoul accrues on ship hulls and increases the resistance of a ship during voyage. This is a widespread issue within the shipping an industry -- which supports the vast majority of global trade. To address this problem, we are developing Bio-Inspired HullCrawler -- an autonomous robot capable of cleaning ship hulls while a ship is underway. The novelty of our design centers on the bio-inspired suction cups that are cast as composite silicon elastomer. The purpose of this thesis is to look specifically at the lateral force resistance of elastomeric suction cup mechanisms. Here we propose new design concepts for the attachment system to improve on the drag force resistance of the HullCrawler device.
by Harith Morgan.
S.B.
S.B. Massachusetts Institute of Technology, Department of Mechanical Engineering
44
Li, Jiajia. « Contributions to modeling of bubble entrainment for ship hydrodynamics applications ». Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/1875.
Texte intégralRésumé :
This thesis presents two important contributions to the modeling of entrainment of air bubbles in water, with focus on ship hydrodynamics applications.
The first contribution consists of a general framework for modeling turbulent air entrainment. The framework attempts to describe the evolution of bubbles from their formation at the free surface, size distribution changes due to breakup and coalescence, and rise due to buoyancy. This proposed framework describes the complex entrainment process as a series of simpler mechanisms which can be modeled independently. For each mechanism a simple but mechanistic model is developed to provide closure while leaving the door open for future improvements. These unique characteristics enable the entrainment model to be used in general problems while still producing results at least as good as the few other available models.
The massive entrainment of air that takes place around a ship leads to very high void fractions and accumulation of bubbles against the hull, particularly underneath the flat regions of the hull and in low pressure regions near appendages. These processes also pose challenges for two phase solvers. As a second contribution in this thesis, numerical algorithms for two phase flows are developed to eliminate the numerical instabilities normally occurring at high void fractions or large void fraction gradients. A hybrid method to improve pressure-velocity coupling for collocated grids is introduced, which keeps advantages typical of staggered grids in mass conservation and face flux computations. A new two phase coupling strategy is developed to guarantee stability at high void fraction. The balanced force method is extended to general curvilinear grids to suppress spurious velocities. The overall methodology provides strong coupling among pressure, velocity and void fraction, while avoiding numerical instability, and works for free-surface flows on dynamic overset grids.
The proposed numerical schemes are tested for 1D and 2D cases. It is shown that the two phase solver is stable and efficient, even under extreme cases. Good mass conservation properties for multigroup simulations are also demonstrated. The air entrainment model is tested for a 2D wave breaking case and compared with extensive experimental data. The results show good predictions for entrainment location and two-phase properties.
Full scale simulations for Athena R/V are performed using the same modeling constants obtained for the 2D wave breaking case. A grid study is also carried out to evaluate grid convergence properties of the model. While the model can predict well experimental data at full scale for the ship, it also shows dramatic improvements respect to previous entrainment models by converging in grid and not needing to re-evaluate the model constants for each new application. The high-speed Kann boat is also simulated at full scale, showing encouraging results for a preliminary entrainment model for aeration due to impact. The proposed numerical schemes are proved stable and robust in high Reynolds number flows with complex relevant geometries. In addition, these full scale simulations also identify modeling and numerical issues for future improvements.
45
Schneider, Nathan A. « Prediction of surface ship response to severe underwater explosions using a virtual underwater shock environment ». Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FSchneider.pdf.
Texte intégralRésumé :
Thesis (Mechanical Engineer and M.S. in Mechanical Engineering)--Naval Postgraduate School, June 2003.Thesis advisor(s): Young S. Shin. Includes bibliographical references (p. 161-162). Also available online.
46
Pasch, Kenneth Alan. « Heuristics for Job-Shop Scheduling ». Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/6847.
Texte intégralRésumé :
Two methods of obtaining approximate solutions to the classic General Job-shop Scheduling Program are investigated. The first method is iterative. A sampling of the solution space is used to decide which of a collection of space pruning constraints are consistent with "good" schedules. The selected space pruning constraints are then used to reduce the search space and the sampling is repeated. This approach can be used either to verify whether some set of space pruning constraints can prune with discrimination or to generate solutions directly. Schedules can be represented as trajectories through a Cartesian space. Under the objective criteria of Minimum maximum Lateness family of "good" schedules (trajectories) are geometric neighbors (reside with some "tube") in this space. This second method of generating solutions takes advantage of this adjacency by pruning the space from the outside in thus converging gradually upon this "tube." One the average this methods significantly outperforms an array of the Priority Dispatch rules when the object criteria is that of Minimum Maximum Lateness. It also compares favorably with a recent relaxation procedure.
47
Walker, Johnathan C. (Johnathan Clyde). « Multi-attribute tradespace exploration for US Navy surface ship survivability : a framework for balancing capability, survivability, and affordability ». Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104296.
Texte intégralRésumé :
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 123-126).
In a political environment of austerity, the importance of understanding the design tradeoffs for new naval ship concept designs cannot be understated. A combination of a tightened shipbuilding budget, large high-priority procurement programs, and an emphasis on affordability will require high level tradeoffs to be made in future ship programs. Understanding tradeoffs in naval ship capability and survivability for the sake of affordability early in concept ship design gives Navy leadership real options for affordable ships and reduces the likelihood of detailed design changes late in the acquisition process. In the naval ship design process capability and affordability are typical "ility" tradeoffs made in traditional tradespace exploration. Ship designers must consider survivability as a third dimension independent of capability and cost. A specific ship system can be costly and improve survivability in a design but not deliver a level of desired capability. This thesis proposes a framework based on existing methodologies to perform tradespace exploration by iteratively determining a concept naval ship design's capability, survivability, and cost across large tradespaces of thousands of concepts. The process determines an optimal set of designs using multi-dimensional Pareto-optimization methods. This thesis also demonstrates methods to navigate the space bound by the optimized set of designs so tradeoffs can be made while preserving the optimal balance of capability, survivability, and cost. Survivability-cost relationships are developed with specific design requirements to provide insight into the amount of investment required to improve naval ship survivability. Understanding capability-survivability-cost tradeoffs ultimately informs a ship designer the premium that must be paid for increased survivability for a desired level of capability.
by Johnathan C. Walker.
Nav. E.
S.M.
48
McKay, Thomas Duncan. « Diagnostic indicators for shipboard mechanical systems using non-intrusive load monitoring ». Thesis, Monterey, California. Naval Postgraduate School, 2006. http://hdl.handle.net/10945/2344.
Texte intégralRésumé :
CIVINSThis thesis examines the use of Non-intrusive Load Monitoring (NILM) in auxiliary shipboard systems, such as a low pressure air system, to determine the state of equipment in larger connected systems, such as the main propulsion engines. Using data collected on previously installed NILM's at the Naval Surface Warfare Center, Philadelphia DDG-51 Land Based Engineering Site (LBES), major event changes were analyzed and diagnosed using power data collected from the in-service low pressure air compressor (LPAC) and the in-service fuel oil pump. Events investigated include main propulsion engine starts and loadings, gas turbine generators starts, major electrical load shifts, and leak insertions into the low pressure air system. An additional NILM was installed on the General Electric LM2500 Universal Engine Controller (UEC) in order to assist in the diagnosis of various state changes. The UEC provides the appropriate interfaces to monitor and control each LM2500 GTM. The UEC controls the application of starter air, ignition power, and fuel to the engine while also receiving feedback of engine parameters from sensors on the engine. Using the combined data received by the LPAC, fuel oil pump, and UEC, a diagnosis system is derived that can detect major events in the engineering plant described above.
CIVINS
US Navy (USN) author
49
Netemeyer, Kristopher David. « A quantitative methodology for mapping project costs to engineering decisions in Naval Ship Design and procurement ». Thesis, Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/4937.
Texte intégralRésumé :
CIVINSApproved for public release; distribution is unlimited
Alternative methods for cost estimation are important in the early conceptual stages of a design when there is not enough detail to allow for a traditional quantity takeoff estimate to be performed. Much of the budgeting process takes place during the early stages of a design and it is important to be able to develop a budget quality estimate so a design is allocated the necessary resources to meet stakeholder requirements. Accurate project cost estimates early in the planning and design processes can also serve as a cost-control measure to assist in managing the design process. With an understanding of the most significant engineering decisions that affect project costs, project team members and stakeholders can proactively make cost-effective decisions during the design process rather than after construction begins and it is too late to prevent going over budget. This research examines the potential of Artificial Neural Networks (ANNs) as a tool to support the tasks of cost prediction, mapping costs to engineering decisions, and risk management during the early stages of a design's life-cycle. ANNs are a modeling tool based on the computational paradigm of the human brain and have proved to be a robust and reliable method for prediction, ranking, classification, and interpretation or processing of data.
50
Sadat, Hosseini Seyed Hamid. « CFD prediction of ship capsize : parametric rolling, broaching, surf-riding, and periodic motions ». Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/427.
Texte intégralRésumé :
Stability against capsizing is one of the most fundamental requirements to design a ship. In this research, for the first time, CFD is performed to predict main modes of capsizing. CFD first is conducted to predict parametric rolling for a naval ship. Then CFD study of parametric rolling is extended for prediction of broaching both by using CFD as input to NDA model of broaching in replacement of EFD inputs or by using CFD for complete simulation of broaching. The CFD resistance, static heel and drift in calm water and static heel in following wave simulations are conducted to estimate inputs for NDA and 6DOF simulation in following waves are conducted for complete modeling of broaching.
CFD parametric rolling simulations show remarkably close agreement with EFD. The CFD stabilized roll angle is very close to those of EFD but CFD predicts larger instability zones. The CFD and EFD results are analyzed with consideration ship theory and compared with NDA. NDA predictions are in qualitative agreement with CFD and EFD.
CFD and EFD full Fr curve resistance, static heel and drift in calm water, and static heel in following waves results show fairly close agreement. CFD shows reasonable agreement for static heel and drift linear maneuvering derivatives, whereas large errors are indicated for nonlinear derivatives. The CFD and EFD results are analyzed with consideration ship theory and compared with NDA models. The surge force in following wave is also estimated from Potential Theory and compared with CFD and EFD. It is shown that CFD reproduces the decrease of the surge force near the Fr of 0.2 whereas Potential Theory fails.
The CFD broaching simulations are performed for series of heading and Fr and results are compared with the predictions of NDA based on CFD, EFD, and Potential Theory inputs. CFD free model simulations show promising results predicting the instability boundary accurately. CFD calculation of wave and rudders yaw moment explains the processes of surf-riding, broaching, and periodic motion. The NDA simulation using CFD and Potential Flow inputs suggests that CFD/ Potential Flow can be considered as replacement for EFD inputs.