Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997. / Includes bibliographical references (leaves 85-87). / by Güvenç S. Şişman. / S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 75-78). / Since the 2000s, there have been several forms of synthetic genetic circuits that have been modeled and experimentally validated. Examples include the toggle switch, repressilator, various configurations of oscillators, and even logic gates. A major goal in synthetic biology is to combine these modules to construct complex circuits for applications including biosensing, biofuel technology, and various medical technologies. However, a significant problem when building complex biomolecular circuits is due to context-dependence: the dynamics of a system are altered upon changes to its context, potentially degrading the system's performance. In this thesis, we study retroactivity, a specific type of context-dependence, by analyzing the effects of loads on a transcription factor applied by the transcription factor's target sites. In particular, we study this loading effect on the model of an activator-repressor oscillator, a widely studied motif in systems and systems biology. Our analysis indicates that strong activation and weak repression are key for a stable limit cycle. Repression can be effectively weakened by adding load to the repressor, while activation can be effectively weakened by adding load to the activator. Therefore, loading the repressor can be employed as a design parameter to establish a stable limit cycle. In contrast, loading the activator is deleterious to the clock. Experimental protocol and preliminary data are presented. The results presented in this thesis may be helpful to provide a method to tune the dynamics of synthetic genetic circuits without using tags and modifying promoter regions. / by Nithin Senthur Kumar. / S.M.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 101-102). / Tracking, monitoring, and documentation of the manufacturing performance are significant for pharmaceutical companies under the regulations of Food and Drug Administration (FDA). However, the current yield data are not consistent and the business procedures for yield data flow are not unified and optimized at the newly merged pharmaceutical company SJP Singapore. Therefore, a systematic analysis of the current yield data processing was performed in four facilities located at two campuses of this company. Through this analysis, the current business procedures were visualized; the various yield concepts were clearly defined; the problems involved and their root causes were identified; the potential solutions were proposed; and a standard business process was developed taking into account the situation of each facility. As a result, the inconsistent yield data were harmonized and procedures in all four facilities were unified and standardized. This revised business process would enable each department to better fulfill its responsibilities and drive decisions on future improvements. / by Nan Jiang. / M.Eng.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 205-207). / In general, vibration energy harvesting is the scavenging of ambient vibration by transduction of mechanical kinetic energy into electrical energy. Many mechanical or electro-mechanical systems produce mechanical vibrations. The kinetic energy associated with these mechanical vibrations represents a potential source of energy for sensors and other electronics. In fact, as the energy requirements for electronics and wireless communications systems has reduced, harvested energy from vibrations has been successfully used to power several wireless sensors. However, these sensors are implemented on systems with harmonic vibration sources. Most ambient vibrations are noisy, wide-band, and/or stochastic. As such, a resonant tuned-mass damper, with a narrow band-width, filters and discards much of the energy in the vibration spectrum, or worse, resonant harvesters will not resonate in stochastic environments. Several solutions are commonly proposed for harvesting energy from wide-band excitations; multiple resonators tuned to different frequencies (farm systems), non-linear systems, input excitation rectification, and frequency tuning are the most common. This thesis addresses some of the wide-band and/or stochastic challenges to vibration energy harvesting by investigating vibration energy harvesting as a power source for sensors and communications in a down-hole environment. This thesis shows that regardless of the transducer, a single resonant harvester tuned to the frequency with the maximum displacement times frequency cubed produces more power than a farm of resonant harvesters tuned to a range of frequencies. Additionally, this thesis shows that an electromagnetic harvester can be passively tuned to increase the power in a non-stationary system with a peak frequency that is a function of time. Finally, this thesis presents a new resonant, rotational architecture, which has the advantage of simultaneously maximizing the coupling inertia and displacement. / by A. Zachary Trimble. / Ph.D.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 65-68). / This work studies the problem of data-driven modeling and stochastic filtering of complex dynamical systems. The main contributions are GP-SUM, a filtering algorithm tailored to systems expressed as Gaussian processes (GP), and the probabilistic modeling of planar pushing by combining input-dependent GPs and GP-SUM. The main advantages of GP-SUM for filtering are that it does not rely on linearizations or unimodal Gaussian approximations of the belief. Moreover, it can be seen as a combination of a sampling-based filter and a probabilistic Bayes filter as GP-SUM operates by sampling the state distribution and propagating each sample through the dynamic system and observation models. Effective sampling and accurate probabilistic propagation are possible by relying on the GP form of the system, and a Gaussian mixture form of the belief. In this thesis we show that GP-SUM outperforms several GP-Bayes and Particle Filters on a standard benchmark. To characterize the dynamics of pushing, we use input-dependent GPs to learn the motion of the pushed object after a short time step. With this approach we show that we can learn accurate data-driven models that outperform analytical models after less than 100 samples and saturate in performance with less than 1000 samples. We validate the results against a collected dataset of repeated trajectories, and use the learned models to study questions such as the nature of the variability in pushing, and the validity of the quasi-static assumption. Finally, we illustrate how our learned model for pushing can be combined with GP-SUM, and demonstrate that we can predict heteroscedasticity, i.e., different amounts of uncertainty, and multi-modality when naturally occurring in pushing. / by Maria Bauza Villalonga. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994. / Includes bibliographical references (p. 120-123). / by James Arthur Brown. / M.S.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (p. 30). / Rising energy prices and increasing price volatility present a problem for many fraternities, sororities, and independent living groups (FSILGs) at MIT. The buildings they occupy are typically quite old, with little insulation and leaky building envelopes, resulting in unnecessary heating energy consumption and expenditures, as well as CO2 emissions. Through simple retrofitting procedures, these levels of consumption, expenditures, and emissions could be greatly reduced. If such measures are implemented, FSILGs would be in a strong position to lead the way in helping MIT to achieve its recently announced emissions reduction goals. To determine the extent of reduction that could be realized, several easy retrofitting measures have been applied in one FSILG, and the resulting consumption has been compared with previous levels. To properly make that comparison, a background of FSILG buildings, their characteristics, and their uses are outlined. Then, the specific retrofits installed are described in detail. After that, the resulting changes in consumption efficiency are examined and compared to historical records. / (cont.) In summary, those findings show a 32% improvement in consumption efficiency, from a pre-retrofit average of 1.07 therms per heating degree day (HDD) to a post-retrofit average of 0.73 therms/HDD. In analyzing these results, it is estimated that $1543 are saved on heating costs, and that CO2 emissions are reduced by 4500 lbs/yr. Finally, given these results, recommendations are made for installing similar retrofits in other FSILGs, and the potential impact of those actions are assessed. / by Steven J. Stoddard. / S.B.

Thesis (S.B.)--Massachusetts Institute of Technology, Department of Mechanical Engineering, 2013. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 53-54). / A compact underwater 3-D imaging system based on the principles of structured light was created for classroom demonstration and laboratory research purposes. The 3-D scanner design was based on research by the Hackengineer team at Rice University. The system is comprised of a low-power, open-source hardware single-board computer running a modified Linux distribution with OpenCV libraries, a DLP pico projector, camera board, and battery module with advanced power management. The system was designed to be low-cost, compact, and portable, while satisfying requirements for watertightness. Future development and applications may involve navigation systems for an autonomous underwater vehicle (AUV). An initial study of 3-D imaging methods is presented, and the strengths and drawbacks of each type are discussed. The structured light method was selected for further study for its ability to produce high-resolution 3-D images for a reasonable cost. The build of the 3-D imaging system was documented for reproducibility, and subsequent testing demonstrated its functions and ability to produce 3-D images. An instruction guide for operation of the device is provided for future classroom and laboratory use. The 3-D imaging system serves as a proof-of-concept for utilizing structured light methods to produce 3-D images underwater. Image resolution was limited by the output resolution of the pico projector and camera module. Further exploration in obtaining ultra high-resolution 3-D images may include use of a more powerful projector and a higher resolution camera board module with autofocus. Satisfactory 3-D scanning validated the performance of structured light scanning above water. However, contaminants in the water hindered accurate rendering by the system while submerged due to light scattering. Future development of a on-the-fly mapmaking system for AUV navigation should include algorithms for filtering light scattering, and hardware should based on an instantaneous structured light system utilizing the Kinect 2-D pattern method. Autofocus and increased projector brightness would also be worthwhile additions. / by Geoffrey E. Dawson. / S.B.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 57-60). / The demand for technological advancement of greenhouse gas conversion and mitigation strategies is ever increasing. In this thesis, a non-aqueous electrochemical platform with metal lithium (Li) as the anode and carbon as the cathode has been developed to convert the most potent greenhouse gas, sulfur hexafluoride (SF 6), into benign solids Li2S and LiF under room temperature conditions at an electrode - electrolyte interface. Galvanostatic discharge demonstrated that the reaction between Li and SF 6 is capable of delivering modest cell voltages up to - 2.4 V vs. Li/Lie and capacities up to ~3800 mAh/gc. The electrochemical reaction between Li and SF6 in two different battery solvents has been characterized with a suite of solid and liquid phase analyses, which showed the reaction to be an 8 - electron transfer process with high Coulombic efficiency. Rotating disk electrode studies were also employed to demonstrate that the overpotential of this system is intrinsically governed by kinetics. This work demonstrates a non-aqueous system capable of both reducing a fluorinated gas, SF6 under room temperature conditions at an electrode surface, and acting as a primary battery based on halogen ligand chemistry. / by Yuanda Li. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994. / Includes bibliographical references (p. 79). / by Thomas C. Chao. / M.S.