Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005. / Includes bibliographical references. / A one-person cardboard structure was designed to temporarily shelter the homeless during harsh weather conditions. The overall form is based on the folding Yoshimura pattern. It is collapsible, wind and water resistant, and structurally rigid. The design is a prototype made from commonly available cardboard sheets and suggests how this material can be manipulated in future models. / by Christine Lin. / S.B.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1955. / Includes bibliographical references (leaf 42). / by Robert Torrey MacKay. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011. / Cataloged from PDF version of thesis. / Includes bibliographical references. / The design of entrained flow gasifiers and their operation has largely been an experience based enterprise. Most, if not all, industrial scale gasifiers were designed before it was practical to apply CFD models. Moreover, gasification CFD models developed over the years may have lacked accuracy or have not been tested over a wide range of operating conditions, gasifier geometries and feedstock compositions. One reason behind this shortcoming is the failure to incorporate detailed physics and chemistry of the coupled non-linear phenomena occurring during solid fuel gasification. In order to accurately predict some of the overall metrics of gasifier performance, like fuel conversion and syngas composition, we need to first gain confidence in the sub-models of the various physical and chemical processes in the gasifier. Moreover, in a multiphysics problem like gasification modeling, one needs to balance the effort expended in any one submodel with its effect on the accuracy of predicting some key output parameters. Focusing on these considerations, a multiscale CFD gasification model is constructed in this work with special emphasis on the development and validation of key submodels including turbulence, particle turbulent dispersion and char consumption models. The integrated model is validated with experimental data from various pilot-scale and laboratory-scale gasifier designs, further building confidence in the predictive capability of the model. Finally, the validated model is applied to ascertain the impact of changing the values of key operating parameters on the performance of the MHI and GE gasifiers. The model is demonstrated to provide useful quantitative estimates of the expected gain or loss in overall carbon conversion when critical operating parameters such as feedstock grinding size, gasifier mass throughput and pressure are varied. / by Mayank Kumar. / Ph.D.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 57-58). / Anaerobic digesters convert organic waste (agricultural and food waste, animal or human manure, and other organic waste), into energy (in the form of biogas or electricity). An added benefit to bio-digestion is a leftover high-grade organic fertilizer. Models of the anaerobic digestion process do exist, but either rely on simple algebraic equations instead of biochemical reactions, or consider so many external parameters that they become overly complicated and require much input information and computation time. This work provides an intermediate kinetic model that predicts biogas output over time with few inputs. This kinetic model is justified by a small-scale laboratory experiment, and parameters are adjusted to match experimental results. This model can be used to optimize design parameters for an anaerobic digester, and provides information such as the relationship between digester sizing and feed rate. The process used here may be expanded to other feedstock materials and repeated for other similar applications, in an effort to expand anaerobic digestion systems as a clean energy source. / by Jonathan Rea. / S.B.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 50-58). / With up to 40% of cancer patients showing metastatic lesions to the brain and a 30% five-year survival rate post-diagnosis, secondary tumors to the brain are a leading cause of cancer-related deaths. Understanding the mechanisms of tumor cell extravasation at the brain is therefore crucial to the development of therapeutic agents targeting this step in cancer metastasis, and to the overall improvement of cancer survival rates . Investigating the interactions between tumor cells and brain stroma is of particular interest due to the site's unique microenvironment. In fact, the interface between brain and blood, known as the blood-brain barrier (BBB), is the tightest endothelial barrier in humans. The presence of tight junctions between brain endothelial cells, coupled with the spatial organization of pericytes and astrocytes around the vasculature, restrict the entry of most solutes and cells into the brain. Yet, the brain constitutes a common metastatic site to many primary cancers originating from the lung, breast and skin. This suggests that tumor cells must employ specific mechanisms to cross the blood-brain barrier. While in vitro models aimed at replicating the human blood-brain barrier exist, most are limited in their physiological relevance. In fact, the majority of these platforms rely on a monolayer of human brain endothelial cells in contact with pencytes, astrocytes and neurons. While this approach focuses on incorporating the relevant cell types of the brain microenvironment, it fails to accurately replicate the geometry of brain capillaries, the barrier tightness of the BBB, and the juxtacrine and paracrine signaling events occurring between brain endothelial cells and stromal cells during vasculogenesis. To integrate these features into a physiologically relevant blood-brain barrier model, we designed an in vitro microvascular network platform formed via vasculogenesis, using endothelial cells derived from human induced pluripotent stem cells, primary human brain pericytes, and primary human brain astrocytes. The vasculatures formed with brain pericytes and astrocytes exhibit decreased cross-section areas, increased endothelial cell-cell tight junction expression and basement membrane deposition, as well as reduced and more physiologically relevant values of vessel permeability, compared to the vasculatures formed with endothelial cells alone. The addition of pericytes and astrocytes in the vascular system was also coupled with increased extravasation efficiencies of different tumor cell subpopulations, despite the lower permeability values measured in this BBB model. Moreover, an increase in the extravasation potential of metastasized breast tumor cells collected from the brain was recorded with the addition of pericytes and astrocytes, with respect to the parental breast tumor cell line. These results were not observed in metastasized breast tumor cells collected from the lung, thus validating our BBB model and providing useful insight into the role of pericytes and astrocytes in extravasation. Our microfluidic platform certainly provides advantages over the current state-of-the-art in vitro blood-brain barrier models. While being more physiologically relevant than most in vitro platforms when it comes to geometry, barrier function and juxtacrine/paracrine signaling between the relevant cell types, our model provides a robust platform to understand tumor cell-brain stromal cell interactions during extravasation. / by Cynthia Hajal. / S.M.

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 35-36). / As professional gaming (e-sports) develops a greater global infrastructure, it will be critical to create league systems in which skill and luck balance to create competitive, exciting, and fair environments. This study uses the most developed e-sport leagues, found in the game League of Legends (LoL), to examine early efforts at crafting such environments. The use of "winning persistence" and Bayesian statistical analyses reveal that best-of-one matches in LoL demonstrate an overall luck-skill ratio similar to professional baseball (MLB) and football (NFL). Best-of-three matches exhibit an understandably higher ratio of skill, similar to professional basketball (NBA). With both match lengths exhibiting viable but significantly different luck-skill ratios, LoL creator, Riot Games has the tools to control how much luck and skill exist in their matches and leagues, setting an important precedent for future leagues and organizations. / by Cameron Douglas. / S.B.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 79-82). / A new method for controlling road noise transmitted through the suspension system of an automobile was developed, using a Lincoln LS automobile as the target vehicle. In this vehicle, road surface roughness generates vibrations that are transmitted into the automobile primary through a single bushing (the "point 4 bushing") on each of the front suspension control arms. An electromagnetic actuator was designed, built, and tested on a Lincoln LS with simulated roads noise. The actuator applies a force across the point 4 bushing, in response to accelerations of the vehicle frame, just inboard of the bushing, with the goal of reducing the net forces transmitted into the vehicle frame, which ultimately produce unwanted interior noise. Several tonal controllers were developed, each designed to operate in a narrow frequency band, and to eliminate the cross member (frame) vibration just inside the point 4 bushing. The tonal controllers were able to eliminate cross member vibration at the desired frequency. Eliminating the cross member vibration resulted in modest reductions interior sound levels. A successful vibration control system (in this vehicle) would need to eliminate cross member vibrations over frequency range 100 to 200 Hz. However, a broadband controller with this electromagnetic actuator system proved to be difficult, due to undesirable non-minimum phase dynamics. / by Kristen Lynn Clements. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994. / Includes bibliographical references (leaves 96-101). / by Joseph T. Padanilam. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (leaves 32-34). / Brain-machine interfaces are a technology with the potential to fundamentally change the way people interact with their environment, but their adoption has been hampered by the invasiveness of conventional implanted cortical microelectrode arrays. Llinás et al. have proposed a novel design for intravascular nanowire electrode arrays, which promise to be less invasive than current technology. Early work utilizing platinum nanowires showed that metal wires are too stiff for this application. Conducting polymer nanowires could be used in place of metal to build electrodes with far lower stiffness and high conductivity. This thesis describes several all-polymer electrode architectures and the fabrication techniques used to build them. Polypyrrole microwire electrodes were first built in order to demonstrate the feasibility of an all-polymer neural recording electrode, and were shown to give high-fidelity intravascular recordings. Polyaniline nanowires were then fabricated by coaxial electrospinning, which was shown to be a viable technique for the manufacture of such wires. These wires will be integrated to form complete nanowire electrodes and tested in animals before moving towards human applications. / by Bryan P. Ruddy. / S.M.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (leaf 34). / A dry sump lubrication system for a Formula SAE race car was designed and manufactured in order to gain the various advantages this type of system affords. A dry sump system stores oil in an external tank and pumps it between the engine and tank as needed. This allows for a shallower oil pan, which permits lower engine placement. This lower placement improves handling through a lower center of gravity. Additionally, the highly stressed racing engine, a Honda CBR 600 F4i, receives more constant lubrication than a conventional wet sump system. The system included design of a new pan, tank and the associated bracketry and hoses that are needed to make the system functional. The design of the system stressed reliability while keeping an eye on weight to minimize it whenever possible. Detailed analysis and the methodology driving the design choices are presented here along with simple dry sump theory. This document serves as the roadmap through the design of the first dry sump system on an MIT FSAE car. It should prove beneficial to the team when the official design report is created for the competition. Lastly, it will help assist future members who certainly aim to refine the package in subsequent years to make it smaller, cheaper, lighter, more reliable and simply better performing overall. / by Ehsan Farkhondeh. / S.B.