Página 11 dos resultados de 1134 itens digitais encontrados em 0.009 segundos

‣ Computer model for a towed submarine communication antenna

Ulrich, Gary A. (Gary Alan), 1962-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 98 leaves; 9603507 bytes; 9603267 bytes; application/pdf; application/pdf
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by Gary A. Ulrich.; Thesis (Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.; Includes bibliographical references (leaves 97-98).

‣ Optimal development of doubly curved surfaces

Yu, Guoxin, 1968-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 100 p.; 6092433 bytes; 6092188 bytes; application/pdf; application/pdf
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by Guoxin Yu.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.; Includes bibliographical references (p. 98-100).

‣ Response surface methods applied to submarine concept exploration

Goggins, David A. (David Alexis), 1966-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 99 leaves; 6252297 bytes; 6252054 bytes; application/pdf; application/pdf
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by David A. Goggins.; 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 89).

‣ An experimental study of the oil evolution in critical piston ring pack regions and the effects of piston and ring designs in an internal combustion engine utilizing two-dimensional laser induced fluorescence and the impact on maritime economics

Vokac, Adam, 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 194 p.; 14835890 bytes; 14862687 bytes; application/pdf; application/pdf
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Faced with increasing concern for lubricating, oil consumption and engine friction, it is critical to understand the oil transport mechanisms in the power cylinder system. Lubricating oil travels through distinct regions along the piston ring pack before being consumed in the combustion chamber, with the oil distribution and dominant driving forces varying substantially for each of these regions. This experimental work focuses on specific regions in the piston ring pack. A detailed 2D LIF (Two Dimensional Laser Induced Fluorescence) study has been performed on the oil distribution observed with the LIF generated real time high-resolution images, as were changes in piston and ring design. The results reveal the third land, located between the second compression ring and the oil control ring, oil flow patterns and timing are consistent and predictable at each operating point. Speed and load variation alter the basic flow pattern and oil balance through a corresponding change in inertia and gas dragging effect respectively, with ring design variation instigating specific and repeatable phenomenon onto the consistent oil flow pattern. Second land, the region between the top two compression rings, geometric and flow patterns throughout the entire cycle of a single cylinder spark ignition engine. The impact of speed and load were experimentally changes were found to have a significant impact on inertia driven oil transport; however...

‣ An assessment of two-phase pressure drop correlations for steam-water systems.

Idsinga, William
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 249 leaves; 10800736 bytes; 10800492 bytes; application/pdf; application/pdf
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Thesis (Nav. Arch.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1975.; Bibliography: leaves 248-249.

‣ Maneuvering of a robotic pike; Maneuvering of Robopike

Kumph, John Muir
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 76 p.; 4101003 bytes; 4100762 bytes; application/pdf; application/pdf
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by John Muir Kumph.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000.; Includes bibliographical references (p. 75-76).

‣ Manning and automation of naval surface combatants : a functional allocation approach using axiomatic design theory

Szatkowski, John J. (John Joseph), 1967-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 432 p.; 36285443 bytes; 36285199 bytes; application/pdf; application/pdf
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by John J. Szatowski.; Thesis (Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000.; Includes bibliographical references (p. 431-432).

‣ Investigation of the stress corrosion cracking susceptibility of annealed and heat treated alloy 625 castings and forgings in sea water; Stress corrosion cracking susceptibility of annealed and heat treated alloy 625 castings and forgings in sea water, Investigation of the

Jones, Eric Merwin
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 104 leaves; 6074705 bytes; 6085531 bytes; application/pdf; application/pdf
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by Eric Merwin Jones.; Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1987.; Bibliography: leaves 100-104.

‣ Surface-surface intersection with validated error bounds

Mukundan, Harish
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 100 p.; 7169137 bytes; 9081249 bytes; application/pdf; application/pdf
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This thesis presents a robust method for tracing intersection curve segments between continuous rational parametric surfaces, typically rational polynomial parametric surface patches. Using a validated ordinary differential equation (ODE) system solver based on interval arithmetic, we obtain a continuous, validated upper bound for the intersection curve segment in the parametric space of each surface. Application of the validated ODE solver in the context of eliminating the pathological phenomena of straying and looping is discussed. We develop a method to achieve a continuous gap-free boundary with a definite numerically verified upper bound for the intersection curve error in parameter space. This bound in parametric space is further mapped to an upper bound for the intersection curve error in 3D model space, denoted as model space error, which assists in defining robust boundary representation models of complex three-dimensional solids. In addition, we also discuss a method for controlling this model space error so that it takes values below a predefined threshold (tolerance). Application of the above method to various examples is further demonstrated.; by Harish Mukundan.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and...

‣ Wave effects on underwater vehicles in shallow water

Sabra, Gregory, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 151 leaves; 8680714 bytes; 8687105 bytes; application/pdf; application/pdf
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by Gregory Sabra.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.; "June 2003."; Includes bibliographical references (leaves 150-151).

‣ Effect of hull-to-bulkhead flexible connection on blast resistance of double hulled ships

Brown, Christian R. (Christian Randall)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 65 p.; 3216558 bytes; 3219189 bytes; application/pdf; application/pdf
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The use of double hull construction is commonplace within the shipping industry though it is largely unexploited within naval vessels. The Impact and Crashworthiness Lab at MIT has proposed the use of adaptive sandwich structures to improve the blast resistance of naval hulls. This project will address two main areas of investigation through the use of simplified analytical models: the integration of hardening and softening plastic core responses in the crushing of a rigidly supported sandwich panel; and the deformation analysis of a sandwich panel supported by non-rigid connections. The analytical solutions were utilized to perform a series of parametric studies to evaluate both the useable range of the models as well as to investigate the general behavior of a sandwich panel under a uniform load when supported by crushable connections. This initial investigation provides the simplified tools to begin and to validate a more detailed, numerical analysis.; by Christian R. Brown.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.; Includes bibliographical references (p. 65).

‣ An evaluation of finite element models of stiffened plates subjected to impulsive loading

Pedatzur, Omri
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 92 leaves; 4503086 bytes; 4506875 bytes; application/pdf; application/pdf
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Different finite element models are evaluated for two very common structures, a cantilever beam and a stiffened plate, subjected to impulsive loading. For the cantilever beam case, the finite element models are one, two or three dimensional models. Various results from the finite element analyses are compared including with analytical solution and a closed-form approximate solution. For the stiffened plate, the models differ from each other by the way the plate and the stiffeners are modeled. Some of the models are very accurate but require much computational resource, while other models are considerably more economic. The purpose of this study was to decide which model is most appropriate for analyzing a ship deck under slamming conditions. The plate modeled with 4-node shell elements and the stiffeners modeled with 2- node iso-beam elements are shown to yield excellent results while requiring reasonable computational resources. In addition to the evaluation of the finite element models, the thesis presents closed- form approximate solutions for both the cantilever beam and the stiffened panel.; (cont.) These simplified solutions can be used to check and validate finite element analyses of similar structures. Furthermore, the analytical solutions can be very useful in understanding the basic physical behavior and the main parameters governing the dynamic response of these structures.; by Omri Pedatzur.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ A solution to the inherent list on Nimitz class aircraft carriers

Wolfson, Dianna
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 159 p.; 6886968 bytes; 6893639 bytes; application/pdf; application/pdf
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Nimitz class aircraft carriers possess an inherent list to starboard that their list control systems (LCS) are typically unable to correct while under Combat Load Conditions. As a result, it has become necessary to use fresh water ballast in a number of inner bottom voids and damage control voids to augment the LCS. Maintaining liquid ballast in damage control voids is unacceptable, as it reduces the design counter flooding capability of the ship, and thus reduces ship survivability. In order to restore the ships operational flexibility and achieve the necessary/desired list correction, this study determines the effect of adding solid ballast to a series of voids/tanks identified on the 2nd, 4th, and 8th decks. Based on ballast density, tank location and capacity, ease of ballast installation, minor tank structural modifications, and a decision making cost analysis, solid ballast was determined to be the most advantageous for use in correcting the inherent list on the Nimitz class aircraft carriers. Fresh water ballast was also examined as a possible alternative, but not as extensively due to the large quantity of water required and its limited ability to achieve a list correction. Nimitz class aircraft carriers currently have an average list of 1.5 degrees and a KG of 47 feet.; (cont.) Since their allowable KG cannot exceed 48.5 feet...

‣ Experimental investigation of tearing fracture in sheets under quasi-static loading

Roach, Michael L. (Michael Louis)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 162 leaves; 7587659 bytes; 7594467 bytes; application/pdf; application/pdf
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Although there has been interest in the behavior of metal plates under blast and projectile loading for many years, definitive open-source analysis has only been recently forthcoming. This analysis is most often in the form of scaled recreations of the dynamic blast event, or "live fire" tests. New developments in methods of recreating blast and projectile induced plate failure using a quasi-static approach provide possible, accurate, alternatives to the cumbersome and expensive live fire test. This research endeavors to develop an accurate, quasi-static method of recreating the petalling phase of blast and projectile failure in metal sheets, based on a modified trousers- type test. By using the trousers-type fracture test the overall plastic bending kinematics of the fractured petal is preserved, as well as the mixed mode (mode one and mode three) fracture. Through analytical and qualitative analysis, a testing apparatus to generate this trousers-type, plastic bending and mixed mode fracture was designed and machined. The apparatus was then used to test thin steel sheets of varying thickness (0.419 and 0.724mm) in order to validate the quasi-static method of recreating the petalling phase through a comparison with analytically derived results.; by Michael L. Roach.; Thesis (Nav. E.)--Massachusetts Institute of Technology...

‣ Feasibility and design of blast mitigation systems for naval applications using water mist fire suppression systems

Kitchenka, Julie A
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 127 leaves; 5651918 bytes; 5657215 bytes; application/pdf; application/pdf
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The recent trend of using fine water mist systems to replace the legacy HALON- 1301 fire suppression systems warrants further study into other applications of the water mist systems. Preliminary research and investigation indicates that fine mists (20-25 pm droplet size) may reduce peak overpressures of a shock wave traveling through a space. Such pressure reductions could be used to mitigate the destructive effects of a shock wave (initiated by an explosive device) traveling through a structure. Currently these blast mitigation effects have only been demonstrated in small-scale shock tube tests and computer simulations. Uncertainty exists as to the scalability of such a system. The intention of this research is to investigate the applicability of such a blast mitigation system for shipboard use. Study into the degree of mitigation necessary to make a system practical for shipboard installation was conducted. In addition, a theoretical study of the mechanisms of blast mitigation using water mists was completed. Preliminary design of a full-scale system was examined.; (cont.) Given the recent trend toward tumblehome hull forms in future Naval Combatant designs, there exists strong applicability of this system in the "dead" spaces created by the shaping of the tumblehome hull. Further work is needed in numerical modeling and laboratory testing of specific phases of the mitigation. The end goal is a feasible design of a blast mitigation system to be used in the outermost spaces of Naval Combatants to protect interior vital system spaces.; by Julie A. Kitchenka.; Thesis (Nav. E.)--Massachusetts Institute of Technology...

‣ Shipboard applications of non-intrusive load monitoring

Ramsey, Jack S
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 130 p.; 7256015 bytes; 7261485 bytes; application/pdf; application/pdf
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The Non-Intrusive Load Monitor (NILM) provides a method of measuring component performance and source power quality through a single point of entry in the power distribution system. A study was performed utilizing the NILM onboard three different ships (along with experimentation in the laboratory) to determine its effectiveness in determining the state of mechanical systems through analysis of electrical power data. Data collected from the Auxiliary Seawater System onboard the USCGC SENECA indicate that the NILM is able to predict several faults (clogged pump inlet strainers, faulty motor/pump coupling, fouled heat exchangers) as well as provide a backup indication of flow levels to heat loads. Data collected from the Sewage System of the SENECA indicate several metrics which can be applied to cycling systems in general to differentiate between periods of heavy usage and fault conditions. Finally, data collected from the Steering System of the SENECA as well as a yard patrol boat operated by the Office of Naval Research shows the potential of the NILM to be used as a control system without the need for separate mechanical transducers.; by Jack S. Ramsey, Jr.; Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and...

‣ The residual strength of a ship after an internal explosion

Surko, Stephen William, 1960-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 117 leaves; 4956977 bytes; 4956784 bytes; application/pdf; application/pdf
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by Stephen William Surko.; 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.

‣ Design of an AUV recharging system; Design of an Autonomous Underwater Vehicle recharging system

Miller, Bryan D. (Bryan David)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 58 p.; 2512997 bytes; 2515331 bytes; application/pdf; application/pdf
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The Odyssey AUV Series uses a Lithium-ion Polymer battery which is able to supply the necessary power for a limited mission time. The current method of recharge includes surfacing the AUV, opening the vehicle, removing the battery from the vehicle and recharging the battery. A different approach is proposed which uses an inductive coupler and power electronics to conduct a battery charge without opening the vehicle or removing the battery.; by Bryan D. Miller.; Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.; Includes bibliographical references (p. 57-58).

‣ Design and analysis of a permanent magnet generator for naval applications

Rucker, Jonathan E. (Jonathan Estill)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 186 p.; 9848454 bytes; 9856284 bytes; application/pdf; application/pdf
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This paper discusses the electrical and magnetic design and analysis of a permanent magnet generation module for naval applications. Numerous design issues are addressed and several issues are raised about the potential improvements a PM generation system can offer. A proposed 16 MW PM generation module design is presented along with a detailed design methodology. Eighty different machines and power conversion modules are sized, designed, and analyzed with a final design selected. Specifically, sizing and detailed machine design and analysis is performed examining the effects of numerous parameters including number of phases, number of poles, magnetic geometry, machine dimensions, and material types. Analytical models are developed to study rotor losses caused by stator winding time and space harmonics and slot space harmonics. Power electronics and conversion modules to connect the high-speed generator to a DC distribution system are designed and analyzed. In depth simulation of the eighty complete systems is performed using the software programs MATLAB (Version 12.0, Mathworks) and PSIM (Version 6.0, Powersim, Inc.).; The 16 MW permanent magnet generation module, consisting of the generator and associated power electronics, provides an excellent alternative to traditional wound rotor synchronous machines. The final design offers significant reductions in both weight and volume. Specifically...

‣ Optimal control theory applied to ship maneuvering in restricted waters

Thomas, Brian S., S.M. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 71 leaves; 3062158 bytes; 3065053 bytes; application/pdf; application/pdf
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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.; 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).