Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, February 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references. / The aim of this investigation is to design educational project enclosures for engineering students at MIT that utilize the laser-cutter, CNC "DiWire" wire bender and various other mechanical engineering tools. Introducing students to the laser-cutter and wire bender gives them hands-on experience with some exciting mechanical tools for fabrication to supplement their courses in electrical engineering. The key objective of this investigation is finding a cheap, safe, professional-looking, easy-to-manufacture setup that teaches students the desired concepts and gives flexibility for Professor Leeb to integrate novel engineering projects into his classes. The second section of this design project is the creation of a soldering iron holder made using components bent on the DiWire. Many design iterations are carried out before settling on the final design and material choice. The soldering iron holder is then incorporated into a larger electrical engineering project. This larger project is a speaker that students put together and house in a special enclosure. / by Larkin V. Sayre. / S.B.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 151-156). / Turbocharging can provide a cost-effective means for increasing the power output and fuel economy of an internal combustion engine. It is commonly used on multi-cylinder engines, but not on commercial single-cylinder engines due to the phase mismatch between the exhaust stroke (when the turbocharger is powered) and the intake stroke (when the engine requires the compressed air). This work explores overcoming the phase mismatch problem by adding an air capacitor: a volume added in series with the intake manifold between the turbocharger compressor and the engine intake. The function of the air capacitor is to buffer the output from the turbocharger compressor and deliver pressurized air during the intake stroke. This research focuses on demonstrating the feasibility of using an air capacitor to enable turbocharging single cylinder internal combustion engines. An analytical model of the system was created from first principles, which showed that the air capacitor turbocharging method could increase power output by up to 40% without heat transfer and up to 70% with heat transfer elements included in the intake manifold (such as an intercooler). An initial, proof-of-concept experiment was created using a generator as a dynamometer. With an air capacitor volume seven times the engine capacity, this setup was able to produce 29% more power compared to the same engine naturally aspirated. A numerical model was developed in Ricardo Wave to predict the performance of turbocharged single cylinder engines with air capacitors under different conditions. An experimental engine with accompanying dynamometer was constructed to demonstrate the effects of manifold sizing on engine performance and to experimentally validate the model. The experiment showed that the model was able to predict power output with an accuracy of 8% of peak power, fuel consumption within 7% error, air mass flow rates with 10% error, and manifold pressures within 7% error. The model was then combined with a simulated annealing optimization scheme in Matlab in order to conceptualize designs for the geometry and timings of single-cylinder turbocharged engines intended for different commercial applications. The optimization showed that adding an air capacitor and turbocharger to a 0.44L engine, with slight modifications to the valve and injector timings, could increase power by 88% compared to natural aspiration. By also modifying the bore and stroke, the turbocharged engine with an air capacitor could reduce fuel consumption by 8% compared to a naturally aspirated engine with equivalent peak power output. / by Michael Buchman. / Ph. D.

Massachusetts Institute of Technology. Dept. of Mechanical Engineering. Thesis. 1966. Sc.D. / Bibliography: leaves [72-74]. / Sc.D.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (p. 54). / The purpose of this thesis is to analyze the specific project value of a chemical company that undertook a major expansion in the late 1990s. The actual details of the investment were unique and conditional on the level of cumulative internal rate of return for the project. This thesis evaluates the project value and the terms of the project financing using Monte Carlo simulation, which is able to take into account the path-dependent nature of the cash flow model. The results of this research are of interest to investors facing similar financing terms or similar investment opportunities in the future. / by Meghan Gibbons. / S.B.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1986. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Bibliography: leaves 150-152. / by Theresa Clara Jenne. / M.S.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (leaves 42-43). / Conventional needle-free injection (NFI) devices are driven by a pressure source generated by either a compressed spring mechanism or compressed inert gas, which have fixed injection (pressure versus time) profiles. The NFI device developed at the Massachusetts Institute of Technology BioInstrumentation Laboratory (MIT BiLab) is novel in its use of a Lorentz force voice coil actuator as the pressure source. With servo-control, the applied pressure can be adjusted for injection conditions such as skin toughness and injection depth. The focus of this thesis was on designing, building and characterizing a more compact version of the current NFI device. The proposed design features a reduction of the diameter of the voice coil motor by packing empty space with an additional set of magnets. A prototype was built, and benchtop tests were conducted to characterize its force sensitivity, the stability of this force sensitivity, and the jet velocity from the syringe. The force sensitivity was found to be 8.3 N/A, and its consistency was shown to be remarkably stable throughout the stroke of the voice coil. It was found that, with a 200 V input, the voice coil exerted a force of 127 N on the syringe piston, which is equivalent to 12.7 MPa; this pressure produced a jet velocity of 162 m/s out of the syringe. / by Diana Lui. / S.B.

Thesis (S.M. in Ocean Systems Management)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007. / Includes bibliographical references (p. 77-79). / This thesis is focused on the discovery of efficient asset allocations with the use of evolutionary algorithms. The portfolio optimization problem is a multi-objective optimization problem for the conflicting criteria of risk and expected return. Furthermore the nonstationary nature of the market makes it a time-changing problem in which the optimal solution is likely to change as time advances. Hence the portfolio optimization problem naturally lends itself to an exploration with multi-objective evolutionary algorithms for time-changing environments. Two different risk objectives are treated in this work: the established measure of standard deviation, and the Value-at-Risk. While standard deviation is convex as an objective function, historical Value-at-Risk is non-convex and often discontinuous, making it difficult to approach with most conventional optimization techniques. The value of evolutionary algorithms is demonstrated in this case by their ability to handle the Value-at-Risk objective, since they do not have any convexity or differentiability requirements. The D-QMOO time-changing evolutionary algorithm is applied to the portfolio optimization problem. Part of the philosophy behind D-QMOO is the exploitation of predictability in the optimal solution's motion. This problem however is characterized by minimal or non-existent predictability, since asset prices are hard to forecast. This encourages the development of new time-changing optimization heuristics for the efficient solution of this problem. Both the static and time-changing forms of the problem are treated and characteristic results are presented. The methodologies proposed are verified through comparison with established methods and through the performance of the produced portfolios as compared to the overall market. In general, this work demonstrates the potential for the use of evolutionary algorithms in time-changing portfolio optimization as a tool for portfolio managers and financial engineers. / by Iason Hatzakis. / S.M.in Ocean Systems Management

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 169-177). / Aerogels are well known as exceptional thermal insulators. Thermal conductivities of 9 to 10 mW/m.K have been achieved at atmospheric pressure, and a moderate vacuum (between 1/3 and 1/10 of an atmosphere) can lower this number even further, to around 5 mW/m.K. However aerogels for insulation purposes are not widespread on the market. One of the major shortcomings of aerogels that prevent them from being more widely used is their extreme mechanical weakness and brittleness. In this thesis, we characterize and explain these low mechanical properties. We then propose a composite structure for a rigid aerogel panel, a sandwich panel with a truss core filled with monolithic aerogel. Mechanical and thermal properties are derived and partially tested for the truss cores. Several designs are studied and mechanical properties are derived in order to compare these designs. Some criteria for an efficient designs are given. Finally, we describe a first attempt to manufacture one of these composite structures on a small scale. / by Thomas Goutierre. / S.M.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 47-48). / An air track is a valuable tool for examining force and motion in the classroom, providing a low-friction environment to observe phenomena. Unfortunately, currently available models have limited functionality and are prohibitively expensive for many schools. To improve access to this helpful device, a number of smaller and less expensive variations on traditional air tracks are designed and tested. From an analysis of test results and theoretical performance calculations, the best design is identified. Further improvements to this design are also suggested. / by Jeremy Ernest deGuzman. / S.B.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014. / Cataloged from PDF version of thesis. / Includes bibliographical references (page 43). / A study on the design of the front suspension geometry and steering system to be used in a solar electric vehicle. The suspension geometry utilizes a double wishbone design that is optimized to fit in the space constraints of the vehicle. The steering system consists of a rack and pinion connected through tie rods to the steering knuckles, largely optimized based on the space within the vehicle. The final suspension geometry consists of upper and lower wishbone lengths of 4.25 inches and 3.75 inches, respectively. This system is optimized to maintain a proper camber angle and minimize scrub due to track distance changes throughout the travel of the suspension. The geometry of the steering system is designed to fit in the vehicle while achieving a near- Ackermann steering condition. The steering knuckle and steering rack extenders, both made out of Aluminum 6061-T6, are designed based off of this geometry and are optimized for weight and machinability. / by Bruce Arensen. / S.B.