Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 95-97). / In this thesis we experimentally investigated the use of sodium chlorate as an oxygen storage medium for use in underwater fuel cell power systems. Research into improving hydrogen storage systems is the primary concern when designing fuel cell systems with access to atmospheric oxygen. However, in an underwater environment, performance of the oxygen storage system cannot be overlooked. Oxygen candles using sodium chlorate offer gravimetric storage densities similar to compressed gas storage while also offering volumetric storage densities greater than both gas and cryogenic liquid oxygen storage. Unfortunately, this technology does not allow for controllable rates of oxygen production and is known to cause fires and occasionally explosions when contaminated with organic materials or exposed to external sources of heat. Though useful as an emergency source of oxygen, sodium chlorate will not be viable for use in power systems until safer and more controllable methods of releasing its oxygen are implemented. During this project we developed a batch method for releasing oxygen from sodium chlorate. Two grams of sodium chlorate with nanoscale cobalt oxide catalyst were loaded into a reaction chamber and heated until decomposition. Afterwards a piston was used to eject the materials from the reaction chamber. This method proved to be safer and more reliable than similar chlorate-based oxygen systems as the primary modes of failure, those associated with the buildup of solid residue at the inlets and exits of the reaction chamber, were removed. Aside from preventing the flow of oxygen to a fuel cell, the over-pressurization caused by these problems could compromise the reaction chamber and potentially result in catastrophic failures. The achieved rate of oxygen production, 0.21 L/min with a heating rate between 25 W and 33 W, was below the target 1.13 L/min needed to operate a 200 W PEM fuel cell. Further assessment of this method will require the use of a more active cobalt oxide catalyst, a system with a larger reaction chamber capable of decomposing increased amounts sodium chlorate per cycle and a reduction in heat losses through the use of improved insulation and thermal isolation techniques. / by Jorge David Garcia. / S.M.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 57-58). / Microgrids, small power distribution networks, are gaining traction as an approach to increasing the fuel efficiency of tactical operations. In order to design controllers for microgrids, accurate models of the generators providing power are needed. In this thesis, non-invasive experimental methods for determining synchronous machine system parameters for a Tactical Quiet Generator (TQG), a generator commonly used by the US military, are explored. While the generator's rotor is at standstill, direct voltage excitation over a large range of excitation frequencies of a synchronous machine's stator is employed to determine electrical parameters for the synchronous machine. With the generator in running, the response of the frequency of generated AC power to a step in load is employed to determine the inertia of the generator's rotor. The stator excitation test is performed with the rotor positioned at a series of angles relative to the stator, so as to determine the location of the principal axes (d and q axes) of the rotor and impedances of the synchronous machine as seen in the d-q reference frame. Least-squares curve fitting is applied to the Bode plots of these impedances to fit the predictions of equivalent circuit models to the data, thus determining the model parameters represented by each equivalent circuit element. For the load step response test, the swing equation is used to calculate the system inertia from measured changes in frequency due to known steps in power. From execution of these techniques, it was determined that they are viable methods for estimating system parameters, though greater precision needs to be exercised in the stator excitation test in order to accurately estimate parameters. / by John Harry Bell, IV. / S.B.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1993. / Includes bibliographical references (p. 150-152). / by James Patrick Ryan. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1961. / Includes bibliographical references (leaf 58). / by John Carl Tamulis. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998. / Includes bibliographical references. / by Alexander V. Staroselsky. / Ph.D.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008. / Includes bibliographical references (leaves 46-47). / This thesis focuses on the design and implementation of a range of experimental methods by optical trapping in order to investigate the mechanical behavior of the leukocyte cell membrane as it undergoes cell rolling. Membrane tethers extracted from the cell during rolling function to slow the cell down and to maintain contact with the endothelial wall. Understanding the dynamic behavior of the leukocyte membrane during rolling motion sheds much insight on the relationship between stages of cell immunological response and the mechanical processes occurring on the surface of the cell membrane. Traditionally, the membrane response during rolling has been probed by simulating the tethering phenomenon in vitro. However, previous work has focused on pulling tethers at a constant velocity where as during in vivo rolling the tether extension will be a function of time. The fundamental differences between constant velocity and rolling-like leukocyte tethering as well as the role of the membrane-cytoskeleton interactions during tethering were specifically focused on in this study. Research work relied on the development of biomechanical optical trapping experiments occurring in an in-vitro setting in an attempt to elucidate an accurate mechanical model accurately describing behavior of the cell during rolling. Initial results indicate that the forces necessary to pull tethers from an immortalized B cell line ranged from 40 pN to 200 pN during linear dynamic behavior, yet ranged from 100 pN to 280 pN during rolling dynamic behavior. Furthermore, a liposome system mimicking functionality of the plasma membrane and lipid reservoir of the leukocyte cell membrane has been developed. Additional experiments are needed to verify preliminary results. / by Sergio Michael Navarro. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008. / Includes bibliographical references (p. 193-200). / Relays and switches are of interest in applications such as test equipment, radar, communications, and power systems, amongst others. Unlike solid state switches, mechanical relays provide galvanic isolation across the power ports. This characteristic is important because, for safety reasons, electrical codes stipulate that loads in certain power applications must be disconnected by open gaps. This requirement imposes significant isolation, heat dissipation, tribology and reliability constraints on a relay.The objective of this research is to explore power handling by a MEMS device in a relay context. This work presents concepts, analytical performance models, fabrication processes and design rules for MEMS relays capable of hot-switching inductive loads in power applications. To this end, a horizontal-displacement, electrostaticallyactuated, MEMS relay for make-break power switching applications is presented. The MEMS-relays are etched in (100) Si through a combination of KOH etching, and DRIE, bonded to a glass substrate, and plated with a 10 /pm thick buffer film of either copper or nickel-cobalt, and a 1-2 [mu]m thick film of a platinum-family metal such as palladium, rhodium, and alloyed palladium (palladium-cobalt).The relays feature { 111}-plane silicon-etched electrical contacts. The { 111}-plane contacts provide travel of 30-80 [mu]m, which prevents arcing. Their oblique geometry introduces contact wipe, which is known to enhance the contact reliability. Further, the contact geometry allows for an enhanced metallization process which provides lower on-state contact resistance than traditional horizontal displacement Mems-relays. Experimental relays exhibit a best-case total on-state contact resistance of 130 m[omega], a response time of 750 [mu]s, a settling time of 3ms, electrical isolation in excess of 1 kV (tested to 997 V with available equipment), a hot switched current of 800 mA using resistive loads, and a hot switched current of 350 mA using a 1 mH inductive load. The relays have been hot-switched in excess of 10⁵ cycles without signs of performance degradation. / by Alexis Christian Weber. / Ph.D.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1938. / MICROFICHE COPY AVAILABLE IN ENGINEERING. MIT copy bound with: Reconstruction of an automobile engine to operate on the more complete expansion cycle / Harvard K. Hecker. 1938. / Includes bibliographical references (leaf 91). / by David Ulrich Hunter. / B.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 123). / This paper details the design and fabrication of a disrupting test rig for measuring the energy required to separate the fuze from the casing of unexploded ordnance (UXO), also called disrupting the device. Preliminary tests were conducted using an explosive disrupting tool and the energy for disruption relative to input kinetic energy was estimated and used to design a test rig with suitable energy to ensure disruption. The disrupting test rig operates on the same principle as a Charpy Notch testing machine, and can deliver up to 3kJ of kinetic energy with its 3m long and up to 137kg mass pendulum arm. A sliding fixture mechanism provides kinematic constraints to allow the fuze body to be pulled out of the casing by the projectile. Measurements taken with the disrupting rig show that disruption can be achieved with as little as 1.5kJ of kinetic energy, assuming the casing is rigidly fixed to ground during disruption. This work will inform further development of a non-explosive tool to replace existing explosive disrupting tools. / by Mark Nathaniel Jeunnette. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1987. / Title as it appeared in the M.I.T. Graduate List June 1987: A simulation of particle bed crushing under compressive loading. / Bibliography: leaves 87-88. / by Gary Joseph Drlik. / M.S.