Página 18 dos resultados de 10406 itens digitais encontrados em 0.015 segundos

‣ Column separation and waterhammer in binary mixture

Kazama, Tsunenori
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 121 leaves; 4405867 bytes; 4405671 bytes; application/pdf; application/pdf
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by Tsunenori Kazama.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1983.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Includes bibliographical references.

‣ Stalled flow characteristics for axial compressors

Koff, Steven Gordon
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 165 leaves; 4166299 bytes; 4166106 bytes; application/pdf; application/pdf
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by Steven Gordon Koff.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1983.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Vita.; Includes bibliographical references.

‣ Concurrent process mapping, organizations, project and knowledge management in large-scale product development projects using the Design Structure Matrix method

Guivarch, Antoine D. (Antoine David), 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 177 p.; 11396770 bytes; 11395797 bytes; application/pdf; application/pdf
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by Antoine D. Guivarch.; Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.; Includes bibliographical references (p. 149-152).

‣ Passive building cooling with thermic diode solar panels.

Manzano Ruiz, Juan J
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 123 leaves; 6039332 bytes; 6039091 bytes; application/pdf; application/pdf
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Thesis (Mech.E)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1977.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Includes bibliographical references.

‣ Manufacture and evaluation of a five-kilowatt axial-flow water turbine

Ho, Lee Wing
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 100 leaves; 4214398 bytes; 4214157 bytes; application/pdf; application/pdf
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by Lee Wing Ho.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1979.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ A ray model for predicting sound attenuation by double barriers

Fano, Paola Crandall
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 121 leaves; 5132362 bytes; 5132121 bytes; application/pdf; application/pdf
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by Paola Crandall Fano.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1979.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Piston slap noise : its transfer through an internal combustion engine

Oguchi, Tetsuro
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 106 leaves; 4864735 bytes; 4864493 bytes; application/pdf; application/pdf
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Tetsuro Oguchi.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1979.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Operator-adjustable frame rate, resolution, and gray scale tradeoff in fixed-bandwidth remote manipulator control

Deghuee, Bradley James
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 100 leaves; 4265507 bytes; 4265267 bytes; application/pdf; application/pdf
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by Bradley James Deghuee.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980.; MICHROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Determination of moisture level in polymers

Kim, Byung Hoon
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 105 leaves; 5886436 bytes; 5886196 bytes; application/pdf; application/pdf
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by Byung Hoon Kim.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography: leaves 91-93.

‣ The application of statistical linearization to nonlinear rail vehicle dynamics

Arslan, Ahmet Vecdet
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 308 leaves; 11957123 bytes; 11956881 bytes; application/pdf; application/pdf
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by Ahmet Vecdet Arslan.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Erosion of metal pipe by solid particles entrained in a liquid

Benchaita, Mohamed Tayeb
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 171 leaves; 8067095 bytes; 8066855 bytes; application/pdf; application/pdf
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by Mohamed Tayeb Benchaita.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Supercritical flow in collapsible tubes

McClurken, Michael E
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 154 leaves; 7392026 bytes; 7391782 bytes; application/pdf; application/pdf
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by Michael E. McClurken.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Improvement of a pantograph for high-speed trains

Wann, Li-Moon
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: vi, 117 leaves; 5749870 bytes; 5749628 bytes; application/pdf; application/pdf
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by Li-Moon Wann.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Dynamic modeling and control of a 50 MW[subscript e] OTEC power plant

Thomas, Gregory Allen
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 263 leaves; 9381981 bytes; 9381738 bytes; application/pdf; application/pdf
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by Gregory Allen Thomas.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

‣ Artificial muscle technology applied towards treating ischemic mitral regurgitation caused by left ventricular remodeling

Sabourin, Nicaulas A. (Nicaulas Alexandre), 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 115 leaves; 5534285 bytes; 5548089 bytes; application/pdf; application/pdf
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Ischemic Mitral Regurgitation (MR) affects a large portion of patients suffering from ischemic heart disease. Significant MR develops in one quarter to one third of patients who suffer from ischemic heart disease and doubles their late mortality rate after a myocardial infarction or revascularization. MR is most often caused by the bulging, or remodeling, of the heart's left ventricle. This remodeling displaces the papillary muscles inside of the ventricle and tethers the mitral valve, preventing it from closing properly. Current treatments attempt to either repair or replace the valve. These treatments require the heart be stopped and the patient be placed on a cardiopulmonary bypass pump for many hours. Both treatment approaches have serious side-effects, including relapse of the MR as quickly as six months post-operatively. This thesis concerns the development of an active artificial muscle patch (AMP) for application to the exterior of the heart. The AMP constructively remodels the heart in order to alleviate MR. Two in-vivo experiments were conducted with a heart-gated fluid pumping apparatus connected to a balloon patch that successfully proofed the concept that an active patch can relieve MR. These experiments also established data on the mechanical requirements of such a patch. An in-vitro heart model was created to test iterations of AMP devices before undergoing further in-vivo studies. Development of an AMP using Nickel-Titanium shape memory alloy was begun and iterations of this device have had early success in in-vitro tests.; by Nicaulas A. Sabourin.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ Piston ring design for reduced friction in modern internal combustion engines

Smedley, Grant, 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 131 p.; 6500312 bytes; 6516588 bytes; application/pdf; application/pdf
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Piston ring friction losses account for approximately 20% of the total mechanical losses in modern internal combustion engines. A reduction in piston ring friction would therefore result in higher efficiency, lower fuel consumption and reduced emissions. The goal of this study was to develop low-friction piston ring designs to improve engine efficiency, without adversely affecting oil consumption, blowby, wear, or cost. These are desirable objectives for today's engine manufacturers as they strive to improve engine performance while trying to meet increasingly stringent emissions regulations. Using an existing piston ring friction and lubrication model, the main contributors to friction in modern internal combustion engines were identified as the top ring around top dead center of the compression/expansion strokes and the oil control ring throughout the engine cycle. Model predictions indicated that the top ring friction could be reduced by implementing a skewed barrel profile design or an upward piston groove tilt design, and oil control ring friction could be reduced by decreasing ring tension. An increase in groove wear was predicted to occur with the upward piston groove tilt design, which could be eliminated by the introduction of a positive static twist on the top ring. An increase in oil consumption was predicted to occur with the low-tension oil control ring design...

‣ Temperature and rate dependent finite strain behavior of poly(ethylene terephthalate) and poly(ethylene terephthalate)-glycol above the glass transition temperature

Dupaix, Rebecca B. (Rebecca Brown), 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 348 p.; 17043648 bytes; 17043406 bytes; application/pdf; application/pdf
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Poly(ethylene terephthalate) is widely used for consumer products such as drawn fibers, stretched films, and soda bottles. Much of its commercial success lies in the fact that it crystallizes at large strains during warm deformation processing. The imparted crystallinity increases its stiffness and strength, improves its dimensional stability, and increases its density. The crystallization process and the stress-strain behavior above the glass transition depend strongly on temperature, strain rate, strain magnitude, and strain state. A robust constitutive model to accurately account for this stress-strain behavior in the processing regime is highly desirable in order to predict and computationally design warm deformation processes to achieve desired end product geometries and properties. This thesis aims to better understand the material behavior above the glass transition temperature in the processing regime. It examines the strain rate, strain state, and temperature dependent mechanical behavior of two polymers: PET and PETG, an amorphous non-crystallizing copolymer of PET, in order to isolate the effects of crystallization on the stress-strain behavior. Experiments over a wide range of temperatures and strain rates were performed in uniaxial and plane strain compression. A constitutive model of the observed rate and temperature dependent stress-strain behavior was then developed. The model represents the material's resistance to deformation with two parallel elements: an intermolecular resistance to flow and a resistance due to molecular network interactions.; (cont.) The model predicts the temperature and rate dependence of many stress-strain features of PET and PETG very well...

‣ Stable, high-force, low-impedance robotic actuators for human-interactive machines

Buerger, Stephen Paul, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 359 p.; 20336327 bytes; 20352191 bytes; application/pdf; application/pdf
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Robots that engage in significant physical interaction with humans, such as robotic physical therapy aids, must exhibit desired mechanical endpoint impedance while simultaneously producing large forces. In most practical robot configurations, this requires actuators with high force-to-weight ratios and low intrinsic impedance. This thesis explores several approaches to improve the tradeoff between actuator force capacity, weight, and ability to produce desired impedance. Existing actuators that render impedance accurately generally have poor force densities while those with high force densities often have high intrinsic impedance. Aggressive force feedback can reduce apparent endpoint impedance, but compromises coupled stability. The common standard for ensuring coupled stability, passivity, can limit performance severely. An alternative measure of coupled stability is proposed that uses limited knowledge of environment dynamics (e.g. a human limb) and applies robust stability tools to port functions. Because of structural differences between interaction control and servo control, classical single-input, single-output control tools cannot be directly applied for design. Instead, a search method is used to select controller parameters for an assumed structure.; (cont.) Simulations and experiments show that this new approach can be used to design a force-feedback controller for a robot actuator that improves performance...

‣ Biomechanical properties of engineered collagen scaffolds

Bonebreak, Christina M. (Christina Michelle)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 35 leaves; 2188306 bytes; 2187505 bytes; application/pdf; application/pdf
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An experiment was performed to determine the effect of crosslinking on the stiffness of collagen scaffolds. Engineered non-crosslinked and dehydrothermally crosslinked chondroitin-6-sulfate collagen scaffolds were hydrated and loaded in tension, and their mechanical properties were compared. It was found that non-crosslinked scaffolds experience an average increase in weight after hydration of 10,353%, compared to 7,265% for crosslinked scaffolds. Hyperelastic material parameters were determined by the Arruda-Boyce eight-chain model, which was fit to the experimental data. This model predicted an average number of rigid links per collagen fiber of 1.3 and 1.21 for crosslinked and non-crosslinked scaffolds, respectively. Additionally, the collagen fiber densities were found to be 2.92 x 1017 for crosslinked networks and 1.68 x 1017 for non-crosslinked networks. These results can be applied to the changes that take place in the cervix at the onset of delivery. It is hypothesized that the crosslinking between collagen fibers in the cervix breaks down during preparation for delivery, allowing more fluid to enter the extracellular matrix and weaken the tissue. By performing tension tests on cervix tissue in vivo, one can produce a theoretical fit to predict relevant collagen network parameters...

‣ Knee design for a bipedal walking robot based on a passive-dynamic walker

Baines, Andrew Griffin
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 30 leaves; 1615966 bytes; 1614773 bytes; application/pdf; application/pdf
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Passive-dynamic walkers are a class of robots that can walk down a ramp stably without actuators or control due to the mechanical dynamics of the robot. Using a passive-dynamic design as the basis for a powered robot helps to simplify the control problem and maximize energy efficiency compared to the traditional joint-angle control strategy. This thesis outlines the design of a knee for the robot known as Toddler, a passive-dynamic based powered walker built at the Massachusetts Institute of Technology. An actuator at the knee allows the robot to bend and straighten the leg, but a clutch mechanism allows the actuator to completely disengage so that the leg can swing freely. The clutch operates by using a motor to rotate a lead screw which engages or disengages a set of spur gears. Control of the knee is accomplished by utilizing the robot's sensors to determine whether or not the knee should be engaged. The engagement signal is then fed through a simple motor control circuit which controls the motor that turns the lead screw. The knee design was successfully implemented on Toddler but more work is required in order to optimize his walking. In order to study the dynamics of walking with knees, we also built a copy of McGeer's original passive walker with knees.; by Andrew Griffin Baines.; Thesis (S.B.)--Massachusetts Institute of Technology...