Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007. / Includes bibliographical references (p. 97-102). / Solid oxide fuel cells (SOFCs) are electrochemical conversion devices that convert various fuel sources directly into electrical energy at temperatures ranging from 600°C to 1000°C. These high temperatures could potentially allow the direct use of various hydrocarbon fuel sources and hydrogen, without the need for expensive noble metal catalysis. Conventional SOFCs are designed in a two-chamber system, separating the fuel and oxidant flow to the anode and cathode, respectively. However, fuel cell manufacturing cost and robustness have proven to be the main challenges to rapid commercialization. A promising alternate method to achieve these requirements and to open up new architecture designs for the SOFC is the development of single-chamber solid oxide fuel cells (SC-SOFCs). SC-SOFCs avoid many of the manufacturing challenges associated with conventional SOFCs, and have shown optimal performance between 500°C and 800°C. This reduces the need for high temperature sealing and a complicated manifold structure; however it also reduces the partial pressure of the gases at the electrodes, which reduces the theoretical obtainable voltage. / (cont.) Microfabrication techniques such as photolithography, sputtering, and photo-resist liftoff were used to create various micro SC-SOFC that are 25-400microns long and 15-40microns wide, utilizing platinum and gold for the electrodes and YSZ as the electrolyte. After successfully fabricating these micro SC-SOFCs, the fuel cells were tested in a microprobestation with a custom gas chamber enclosure, which was exposed to CH4:02:N2 at 20:20:100 ccm or 40:20:100 ccm. A switch in the OCV from a negative voltage to a positive voltage was observed around 600°C, possible indicating change in electrochemical reactions with temperature. An OCV of [approx.] 0.4V and peak power density of 27[mu]W/cm2 at 900°C in a 1:1 methane:oxygen ratio was achieved. A stack of 10 micro SC-SOFCs as fabricated showing a cumulative OCV of 3.3 V, of an average 0.33 V per cell at 600°C in a 2:1 methane:oxygen ratio. Ongoing research will involve characterizing micro SC-SOFCs to understand the fundamental reaction mechanisms, electrode materials, and architectures to obtain dense, high performing stacks of micro SC-SOFCs. / by Ethan Jon Crumlin. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (p. 114-116). / Investment and operational decisions involving commodities are taken based on the forward prices of these commodities. These prices are volatile, and a model of their evolution must correctly account for their volatility and correlation term structure. A two-factor model of the forward curve is proposed and calibrated to the crude oil, shipping, natural gas, and heating oil markets. The theoretical properties of this model are explored, with focus on its decomposition into independent factors affecting the level and slope of the forward curve. The two-factor model is then applied to two problems involving commodity prices. An approximate analytical expression for the prices of Asian options is derived and shown to explain the market prices of shipping options. The floating storage trade, which appeared in the oil market in late 2008, is presented as an optimal stopping problem. Using the two-factor model of the forward curve, the value of storing crude oil is derived and analyzed historically. The analytical framework for physical commodity trading that is developed allows for the calculation of expected profits, risks involved, and exposure to the major risk factors. This makes it possible for market participants to analyze such physical trades in advance, creates a decision rule for when to sell the cargo, and allows them to hedge their exposure to the forward curve correctly. / by Per Einar S. Ellefsen. / S.M.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 49-50). / In order to successfully deploy the mobile desalination technology being developed at the Rohsenhow Kendall Heat Transfer Laboratories, it is necessary to design a three dimensional, solid model of the technology. This Humidification Dehumidification (HDH) based technology aims to be applied at community level water supplies, bringing clean water to those countries with inadequate water infrastructure. The mobility provided by the model would allow the HDH based desalination setup to be moved to other communities with a higher demand for clean water at a moment's notice. The model described herein describes a preliminary plan on how to organize the components of the desalination system. Two systems were created for this purpose, a single-dehumidifier system (SDS) and a multiple-dehumidifier system (MDS). These systems maximize on the amount of accessible space while minimizing on used material. While the SDS assembly may need rearrangement due to a federal width limitation preventing its deployment in the US, the MDS assembly is more promising. Nonetheless, the SDS assembly may still be deployed in areas such as India or Africa, where regulations are not as stringent. / by Jeffrey H. Huang. / S.B.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007. / Includes bibliographical references. / This work applies concepts from industrial ecology to analyses of manufacturing, recycling, and efficiency. The first part focuses on an environmental analysis of machining, with a specific emphasis on energy consumption. Energy analyses of machining show that in many cases, the energy of actual material removal represents only a small amount of the total energy used in machining, as auxiliary processes can have significant energy requirements. These analyses also show that the embodied energy of the materials that are machined can far exceed the energy of machining. Such energy consumption data, along with material flow data, provide much of the information necessary to evaluate machining on the basis of environmental performance. The second part of this work focuses on material recycling at product end-of-life. In this section, a means of evaluating the material recycling potential for products is presented. This method is based on two measures: the value of the materials used in a product and the mixture of materials used in a product. This simple representation is capable of differentiating between products that are economically worthwhile to recycle and those that are not. / (cont.) Such information can in turn be used to help guide product design and recycling policy. The third part of this work focuses on the effectiveness of efficiency improvements in reducing environmental impact. Historical data from ten activities show that improvements in efficiency are rarely able to outpace increases in production. Thus, the overall impact of each of these activities has increased over time. Specific conditions and policies that do allow for efficiency improvements to reduce impact are identified and explored. Together, the three topics presented here provide information, analyses, and recommendations to help move industrial systems towards sustainability. / by Jeffrey B. Dahmus. / Ph.D.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014. / Cataloged from PDF version of thesis. / Includes bibliographical references (page 75). / Micro-contact roll printing is an emerging alternative to photolithography as a means of cheaply manufacturing MEMS devices. Micro-contact roll printing control systems can regulate the printing pressure of a polydimethylsiloxane stamp on a polymer sheet, but the technology cannot adequately control the registration of the stamp on the sheet because the precise dynamic mechanical behavior of the polydimethylsiloxane stamp is unknown. The purpose of this thesis is to apply system identification techniques to characterize the dynamic behavior of samples of polydimethylsiloxane by constructing a test environment that can apply an input force at various frequencies and measure the output force and position at the test sample. A mechanical structure which integrates a voice coil actuator with a load cell and linear variable differential transformer was designed for this purpose. A model and controller were also built to predict the dynamic behavior of the polydimethylsiloxane. In future work the mechanical structure and controller will be integrated and used to fully characterize the behavior of polydimethylsiloxane and other polymers used in micro-fabrication processes. / by Emma Claire Benjaminson. / S.B.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 93-96). / Wider use and adaptation of microfluidic systems is hindered by the infrastructure, knowledge, and time required to build prototype devices, especially when multiple fluid operations and measurements are required. As a result, rapid prototyping methods based on planar and three-dimensional printing are attracting interest; however, these techniques cannot produce structures with the resolution, smoothness, and feature size needed for standard microfluidic devices. Herein I present a new approach to rapidly construct modular microfluidic systems by modification and assembly of interlocking injection-molded blocks. I demonstrate this principle using micromilling of store-bought LEGO® bricks to create surface fluidic pathways on bricks, and develop procedures for sealing and interconnecting bricks to form modular, reconfigurable microfluidic systems. Micromilling using a desktop machine achieves channel dimensions of 50 pm in depth and 150 pm in width, or greater, etched into the sidewalls of blocks. Sealing these channels with adhesive films allows internal fluid pressure of at least 400 kPa. The intrinsic tolerances of injection molded bricks and their elastically averaged connections gives mechanical locating repeatability of 1 pm, which enables fluid to pass between bricks via an O-ring with >99.9% sealing reliability. Using the LEGO-based approach, I build systems made of assembled brick units for generating droplets, sensing light, sorting with inertial and magnetic forces, and repeatably positioning a smartphone camera, and characterize their performance. Then, I fabricate and measure LEGO-like bricks made by FDM and SLA three-dimensional printing, showing that they can integrate with injection-molded bricks to add useful function, although their surface quality, resolution, and material limit performance. In addition, I adapt these components for two educational activities for high school students: a colorimetric titration device and a modular designable boat. The standard interface among all bricks enables a wide variety of brick units to be incorporated onto a common platform, making this "lab on a brick" a new and viable platform for advancing research and education in microfluidics. / by Crystal Owens. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1990. / Includes bibliographical references (leaves 62-63). / by Akira Kitano. / M.S.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004. / Includes bibliographical references (leaves 29-31). / An experimental and numerical study was conducted to better understand the mechanics of motion of the three-linked swimmer in viscous fluid. Numerical studies in C++ were used to predict the velocity and motion of the swimmer using a modified analytical model that considers the dynamical and orientational effects of rods at the surface of a fluid. Computational simulations were graphically used to understand the pressure and velocity distributions of the fluid-structure interactions of the three-linked swimmer, with slightly different movement, using an immersed boundary method computer program. Experiments using a mechanical prototype of a three-linked swimmer were conducted to validate and compare the numerical predictions derived from computational studies. Experimental results indicate that a flexible armed swimmer is more than three times as fast as its rigid armed counterpart. The analytical model presented in this study and the corresponding computational numerical simulations were found to capture the trends of the motion, and the predicted horizontal velocity came within 66% in value of the recorded experimental data. / by Susan YeYoung Ji. / S.B.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 30-31). / The Global Leadership Program (GLP) is a chance for approximately 35 Singapore University of Technology and Design (SUTD) students to travel to the Massachusetts Institute of Technology (MIT) and participate in a cross-university cultural and educational exchange. The students have the opportunity to collaborate with and learn from MIT's own students and faculty during the program. The highlight of the summer is a nine-week design-build course, referred to as the Engineering Design Challenge, which teaches the fundamentals of engineering design and the necessary fabrication skills to execute those designs. The challenge requires small teams to design and build a single-person electric vehicle (EV). The first two years, the challenge was to make go-karts; since then, the scale has been increased to electric boats. The design challenge is presented as a real-world engineering exercise by intentionally being open-ended and primarily student-driven. It requires the students to practice both their technical skills as well as their interpersonal, professional, and leadership skills. This sort of allencompassing, immersive approach to education is based on principles found within the Project- Based Learning (PBL) and Conceive-Design-Implement-Operate (CDIO) pedagogical frameworks. Though it has only been around since 2013, the program has had a lasting impact on both the students that participated and their peers upon their return to Singapore. Elements of MIT's own student culture were shared with the participants and successfully transplanted back to SUTD at the program's end. This sort of cross-university educational and cultural exchange has exciting implications for expanding the global engineering educational network as the world becomes more and more connected. / by Paige Lynette Reiter. / S.B.

Thesis (M.S.)--Massachusetts Institute of Technology. Dept. of Mechanical Engineering, 1967. / Each fold. diagr. numbered as several pages. / Bibliography: leaves 118-119. / by Stephen Henry Kaiser. / M.S.