Liquid crystal elastomers (LCEs) are materials formed by cross-linking crystal mesogens into a flexible polymer network, and they display soft behavior and undergo large, reversible strains. The mesogenic order determines material properties, causing coupling between temperature, liquid crystalline order, and deformation, which leads to temperature-based actuation. LCEs have important applications in soft robotics and medical devices, so attempts have been made to theoretically model their behavior in order to develop new use cases. One such model, developed by Lee (2021), identifies regions of liquid crystal orientation and has agreed with initial experimental data (Lee et al., 2023). This thesis aims to characterize the behavior of isotropic-genesis polydomain LCEs across various temperatures, strain rates, and crosslinking densities and further test the model by comparing the experimental data against it.
\r\n\r\nTensile tests were run across five strain rates (10\u207b\u00b9/s, 5\u00d710\u207b\u00b2/s, 10\u207b\u00b2/s, 5\u00d710\u207b\u00b3/s, 10\u207b\u00b3/s), three temperatures (26\u25e6C, 55\u25e6C, 90\u25e6C), and two crosslinking densities (50 mol%, 25 mol%). A custom tensile rig with a heated chamber made by Lee (2021) was modified for the purpose of this thesis to allow for digital image correlation and trials across temperatures.
\r\n\r\nThese tensile tests revealed that stiffness increased with faster strain rates, and, as temperature increased, soft behavior was reduced at 55\u25e6C and vanished at above the nematic transition temperature. Additionally, residual strain decreased with increasing temperature, at \u223c1.5 at 26\u25e6C, \u223c0.75 at 55\u25e6C, and \u223c0.1 at 90\u25e6C. Reducing the crosslinking density more than doubled the strain at failure and drastically\r\nincreased the region of soft behavior.
\r\n\r\nExperimental data across three strain rates (10\u207b\u00b2/s, 5\u00d710\u207b\u00b3/s, 10\u207b\u00b3/s), three temperatures, and at 50 mol% crosslinking density were compared against the model developed by Lee (2021). The soft behavior of the LCE was generally well characterized by the model, however, the model deviated from experimental data above two strain, as the Neo Hookean-based model was unable to capture strain hardening. Since higher temperature trials were run to lower strains, the model was able to better capture the full behavior of the LCE at higher temperatures, even with the loss of soft behavior at 90\u25e6C. This model is therefore a useful tool for modeling LCE soft behavior across various temperatures.
" }, { "name": "Nandi, Ankita", "degree": "Senior Thesis", "year": "2024", "title": "Characterizing the Molecular Structure of Preceramic Polysiloxanes for Freeze Casting of Silicon Oxycarbide Ceramics", "advisor": "Faber, Katherine T.; Rossman, George Robert", "url": "https://resolver.caltech.edu/CaltechTHESIS:06132024-150611460", "creators": [ { "name": { "family": "Nandi", "given": "Ankita" }, "id": "Nandi-Ankita", "orcid": "0000-0002-8158-8509", "display_name": "Nandi, Ankita" } ], "advisors": [ { "name": { "family": "Faber", "given": "Katherine T." }, "id": "Faber-K-T", "orcid": "0000-0001-6585-2536", "role": "advisor", "display_name": "Faber, Katherine T." }, { "name": { "family": "Rossman", "given": "George Robert" }, "id": "Rossman-G-R", "orcid": "0000-0002-4571-6884", "role": "co-advisor", "display_name": "Rossman, George Robert" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "english", "matsci" ], "doi": "10.7907/akf6-7631", "abstract": "Preceramic polymers are frequently used as a lower energy intensive precursor for creating ceramics, as they can be transformed into robust ceramics at lower temperatures than is required by traditional processing routes. Additionally, preceramic polymers can be used to produce structures with microstructural variability, such as porosity. Polysiloxanes are one type of preceramic polymer that have been used to create silicon oxycarbide materials. Previous research has utilized polysiloxanes in freeze casting to create porous ceramics, specifically investigating development of different pore morphologies and pyrolysis profiles. However, there has been little exploration into the differing molecular structures of various polysiloxanes impact their behavior through the freeze casting process. Investigating the molecular structure of commonly used proprietary polysiloxane Wacker SILRES\u00ae MK has provided some insight into molecular structural changes during the freeze-casting process. These can be used to improve freeze-casting microstructure from another proprietary polysiloxane, Wacker SILRES\u00ae H44. MK and H44 were characterized in powder, solution, and post pyrolysis stages of the freeze casting process. Techniques including FTIR-ATR spectroscopy, Raman spectroscopy, NMR spectroscopy, DSC, and SEM imaging were used to determine how to improve the robustness of freeze cast structures made with H44. MK was determined to be a polymethylethoxysiloxane, and H44 to be a polymethylphenylsiloxane. The high energy and high steric strain phenyl groups in H44 require additional energy to facilitate crosslinking during the freezing process for H44. Both MK and H44 converted to silicon oxycarbide upon pyrolysis. Adding crosslinker improved the desired porous microstructure and robustnesss of freeze-cast structures made with H44, as evidenced by SEM imaging. Future exploration into other preceramic polymers should consider the impact of high energy functional groups upon the processing methods to create desired microstructures.
" }, { "name": "Nandi, Ankita", "degree": "Senior Thesis", "year": "2024", "title": "Thinking Queerness and Forming Intimacies: Understanding Identity, Relationships, and Queerness in South Asian Diasporic Contemporary Literature, 1981\u20132022", "advisor": "Murphy, Dana", "url": "https://resolver.caltech.edu/CaltechTHESIS:03192024-215940431", "creators": [ { "name": { "family": "Nandi", "given": "Ankita" }, "id": "Nandi-Ankita", "orcid": "0000-0002-8158-8509", "display_name": "Nandi, Ankita" } ], "advisors": [ { "name": { "family": "Murphy", "given": "Dana" }, "id": "Murphy-Dana", "orcid": "0000-0003-1710-5768", "role": "advisor", "display_name": "Murphy, Dana" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "english", "matsci" ], "doi": "10.7907/6v3z-tw65", "abstract": "Reading intimacy in South Asian diasporic texts requires a nuanced framework to understand the impersonality of sex, and blurrings within relationships and intimacies. Intimacy, both emotional and physical, depends on vulnerability to connect with others. I use a queer diasporic framework to analyze a selection of scenes from different contemporary South Asian diasporic texts, from 1981\u20132022. Specifically, I analyze their portrayals of intimacy and relationships to disrupt binaries invoked on how we might view intimacy. Such a framework also affords insights into how the diaspora and queerness both influence identity and disrupt heterosexual readings of texts to allow for deeper emotional intimacies. The framework is grounded in queer theory, history of the LGBTQ+ community and the queer body, and history of the diaspora to allow for nuanced readings of the texts. Through exploring the queer diaspora in these contemporary texts, I challenge binaries of both the queer and diasporic frameworks in ways that encompass the complexities of the relationships we find ourselves in." }, { "name": "Anand, Emile Timothy", "degree": "Senior Thesis", "year": "2023", "title": "Pseudorandomness of the Sticky Random Walk", "advisor": "Umans, Christopher M.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06142023-102020321", "creators": [ { "name": { "family": "Anand", "given": "Emile Timothy" }, "id": "Anand-Emile-Timothy", "orcid": "0000-0003-2893-9469", "display_name": "Anand, Emile Timothy" } ], "advisors": [ { "name": { "family": "Umans", "given": "Christopher M." }, "id": "Umans-C-M", "orcid": "0000-0003-2893-9469", "role": "advisor", "display_name": "Umans, Christopher M." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "compsci" ], "doi": "10.7907/ze1k-6v37", "abstract": "We extend the pseudorandomness of random walks on expander graphs using the sticky random walk. Golowich and Vadhan recently showed that expander random walks can fool all symmetric functions in total variation distance (TVD) up to an O(\u03bb pp) error in total variation distance, where lambda is the second largest eigenvalue of the expander and p is the size of the arbitrary alphabet used to label the vertices. It has been conjectured that the dependency on the pp term is not tight.
\r\n\r\nIn this paper, we resolve the conjecture in the affirmative for a family of expanders. We present a generalization of Guruswami and Kumar's sticky random walk for which prior results predicts a TVD upper bound of O(\u03bb pp) using a Fourier analytic approach. For this family of graphs, we use a combinatorial approach involving the Krawtchouk functions to derive a strengthened TVD of O(\u03bb). Furthermore, we present equivalencies between instances of the generalized sticky random walk, and, using linear-algebraic techniques, show that the generalized sticky random walk is an infinite family of expanders.
" }, { "name": "Jiang, Abigail Yuan-Shan", "degree": "Senior Thesis", "year": "2023", "title": "Who\u2019s Chinatown, Whose Chinatown? Visions of Urban Progress in Los Angeles Chinatown, 1970-2020", "advisor": "Dykstra, Maura", "url": "https://resolver.caltech.edu/CaltechTHESIS:06202023-215355092", "creators": [ { "name": { "family": "Jiang", "given": "Abigail Yuan-Shan" }, "id": "Jiang-Abigail-Yuan-Shan", "orcid": "0000-0001-8003-8380", "display_name": "Jiang, Abigail Yuan-Shan" } ], "advisors": [ { "name": { "family": "Dykstra", "given": "Maura" }, "id": "Dykstra-M", "orcid": "0000-0001-6036-6440", "role": "advisor", "display_name": "Dykstra, Maura" } ], "committee": [ { "name": { "family": "Wiggins", "given": "Danielle L." }, "id": "Wiggins-Danielle-L", "orcid": "0000-0001-8457-8827", "role": "chair", "display_name": "Wiggins, Danielle L." } ], "option_major": [ "history", "matsci" ], "doi": "10.7907/94nx-2495", "abstract": "This thesis explores the dynamics of urban development in Los Angeles (LA) Chinatown since the 1970s until present day. The historical narrative is driven by broad demographic shifts across LA County, alongside municipal and community politics that shape the material and cultural demands behind neighborhood change. Through this narrative, I challenge the traditional framings of resident versus business interests in Chinatowns, and instead highlight the complicated and often competing visions of progress throughout the community. I argue that \u201cthe youths\u201d and \u201cthe elders\u201d serve as key figures in this history: first, as dynamic actors and activists directly engaged in the process of development, and second, as subjects of discourse that actors mobilize towards different goals of development. Finally, I illuminate tensions between organizing as a representative of a community and organizing in solidarity towards the tangible needs of a community." }, { "name": "Cheng, Myra Miaobo", "degree": "Senior Thesis", "year": "2022", "title": "Female Inventors and Narratives of Innovation in Late Twentieth-Century Computing", "advisor": "Dykstra, Maura", "url": "https://resolver.caltech.edu/CaltechTHESIS:08012022-200204789", "creators": [ { "name": { "family": "Cheng", "given": "Myra Miaobo" }, "id": "Cheng-Myra-Miaobo", "display_name": "Cheng, Myra Miaobo" } ], "advisors": [ { "name": { "family": "Dykstra", "given": "Maura" }, "id": "Dykstra-M", "orcid": "0000-0001-6036-6440", "role": "advisor", "display_name": "Dykstra, Maura" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "compsci", "history" ], "doi": "10.7907/79me-jr94", "abstract": "I examine the history of women\u2019s labor and representation in computer science by studying two distinct categories: women involved in authorial, creative work versus manual, computational labor. Building off the work of historians of technology, I question why we tell the histories we do about the \u201cforgotten women.\u201d The gaps in the histories of computer science innovation are mirrored by shortcomings in the actual practice of computer science: Both the historiography of computer science and the field itself have been shaped by the myth of the lone genius. I trace the shortcomings of this myth throughout the history of modern computer science, finding that narratives of female innovators and movements to incorporate more women into computing only perpetuated connections between individual genius, masculinity, and scientific progress. I explore community-based perspectives from feminist epistemology as possibilities for shifting away from the myth of the lone genius." }, { "name": "Zou, Sarah Jin", "degree": "Senior Thesis", "year": "2022", "title": "An Efficient Environment Encoding for Trajectory Feasibility and Cost Predictions", "advisor": "Yue, Yisong", "url": "https://resolver.caltech.edu/CaltechTHESIS:12142023-183159114", "creators": [ { "name": { "family": "Zou", "given": "Sarah Jin" }, "id": "Zou-Sarah-Jin", "orcid": "0009-0007-5275-9739", "display_name": "Zou, Sarah Jin" } ], "advisors": [ { "name": { "family": "Yue", "given": "Yisong" }, "id": "Yue-Yisong", "orcid": "0000-0001-9127-1989", "role": "advisor", "display_name": "Yue, Yisong" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "eleceng" ], "doi": "10.7907/605s-5h91", "abstract": "An efficient method to encoding a robot\u2019s surrounding is important for the safety and scalability of path planning problems. I present a method for encoding occupied spaces in an environment via parametric geometry (e.g. circles). This encoding is utilized to train a cost and feasibility predicting neural network for path planning between two states. The circle encoding method uses either bounding circles or set cover to provide a lower dimension input of environments for neural network. The lower input dimension of the models allows for a smaller and faster model of similar performance. Feasibility and cost prediction neural networks enable lazy planning for trajectory calculation. While there are no safety-guarantees, the model I present can act as an heuristic to identify the best paths, amortizing a robot\u2019s onboard computation. To train a cost and feasibility predicting model, I first generate multiple environments and calculate encoding circles for obstacle-occupied spaces. For each environment, I use planners to calculate multiple trajectories and store their feasibility and cost. I then train the feasibility and cost prediction models from this data . The feasibility model has 90% accuracy on train and test environments. The circle encoding method was compared with occupancy grid encoding method. When encoding methods were compared to predict occupied space, models with circle encoding generalized to unseen environments better than occupancy grid input models. The method of circle encoding I introduce can be utilized in other learning problems that use environment as input. The feasibility and cost predictions done in this work can be applied to bias tree growth or to other global planning methods." }, { "name": "Gokuli, Mahi", "degree": "Senior Thesis", "year": "2021", "title": "A Combined High Temperature Tape-Casting and 2D Freeze-Casting Method for Polymer Membranes with Vertically Oriented Pores", "advisor": "Faber, Katherine T.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06062021-034939530", "creators": [ { "name": { "family": "Gokuli", "given": "Mahi" }, "id": "Gokuli-Mahi", "orcid": "0000-0001-9771-826X", "display_name": "Gokuli, Mahi" } ], "advisors": [ { "name": { "family": "Faber", "given": "Katherine T." }, "id": "Faber-K-T", "orcid": "0000-0001-6585-2536", "role": "advisor", "display_name": "Faber, Katherine T." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "matsci" ], "doi": "10.7907/ywpf-cx09", "abstract": "Alternatives to lithium-ion batteries often require novel electrolytes, such as solvent-in-salt electrolytes and ionic liquids, for which commercial battery separators are unsuited. The Faber Lab at Caltech is researching processing methods for separators made of polymer/ceramic composite materials to ensure high wettability in novel liquid electrolytes. To this end, a flexible polymer separator is needed which provides a short working-ion transportation path for high ionic conductance. Here, a method was developed for the fabrication of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membranes with vertically aligned, nontortuous pores with pore diameters of a few microns by directional crystallization of dimethyl sulfone (DMSO\u2082). The method combines high-temperature tape casting\r\nand bidirectional freeze casting into a single step. Important considerations for the improvement of the method (particularly, avenues for reducing the pore size to below 1 \u03bcm) are discussed. In addition, the role of PVDF-HFP crystallization in bidirectional freeze-casting, a solvent crystallization method, is discussed." }, { "name": "Merk, Liana Noor", "degree": "Senior Thesis", "year": "2021", "title": "Engineering Logical Inflammation Sensing and Secreting Circuit for Gut Modulation", "advisor": "Murray, Richard M.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06042021-234419803", "creators": [ { "name": { "family": "Merk", "given": "Liana Noor" }, "id": "Merk-Liana-Noor", "orcid": "0000-0001-9711-954X", "display_name": "Merk, Liana Noor" } ], "advisors": [ { "name": { "family": "Murray", "given": "Richard M." }, "id": "Murray-R-M", "orcid": "0000-0002-5785-7481", "role": "advisor", "display_name": "Murray, Richard M." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "bioeng" ], "doi": "10.7907/wr7s-6436", "abstract": "The mammalian gut contains trillions of microbes that interact with host cells and monitor changes in the environment. Opportunistic pathogens exploit environmental conditions to stimulate their growth and virulence, leading to a resurgence of chronic disorders such as inflammatory bowel disease (IBD). Current therapies are effective in less than 30% of patients due to the lack of adherence to prescription schedules and overall, off-target effects. Microbial therapeutics can be engineered to colonize the gut, providing in situ surveillance and conditional disease modulation. However, many current engineered microbes can only respond to single gut environmental factors, limiting their effectiveness. In this work, we implement a previously characterized split activator AND logic gate in the probiotic E. coli strain Nissle 1917. Our system can respond to two input signals: the inflammatory biomarker tetrathionate and a second input signal, IPTG or aTC. We report 4-6 fold induction with minimal leak when both signals are present. We model the dynamics of the AND gate using chemical reaction networks, and by tuning parameters in silico, we identified perturbations that affect our circuit\u2019s selectivity. We then engineer our optimized AND gate to secrete an anti-inflammatory therapeutic cytokine, IL-22, using the hemolysin secretion pathway. We anticipate that our results will prove useful for designing living therapeutics for spatial targeting and signal processing in complex environments.
" }, { "name": "Neamati, Daniel A.", "degree": "Senior Thesis", "year": "2021", "title": "New Method and Analysis of Proximity Trajectory-Only Learned Dynamics for Small Body Gravity Fields", "advisor": "Chung, Soon-Jo", "url": "https://resolver.caltech.edu/CaltechTHESIS:05272021-220554457", "creators": [ { "name": { "family": "Neamati", "given": "Daniel A." }, "id": "Neamati-Daniel-A", "orcid": "0000-0002-1555-1433", "display_name": "Neamati, Daniel A." } ], "advisors": [ { "name": { "family": "Chung", "given": "Soon-Jo" }, "id": "Chung-Soon-Jo", "orcid": "0000-0002-6657-3907", "role": "advisor", "display_name": "Chung, Soon-Jo" } ], "committee": [ { "name": { "family": "Minnich", "given": "Austin J." }, "id": "Minnich-A-J", "orcid": "0000-0002-9671-9540", "role": "chair", "display_name": "Minnich, Austin J." }, { "name": { "family": "Chung", "given": "Soon-Jo" }, "id": "Chung-Soon-Jo", "orcid": "0000-0002-6657-3907", "role": "member", "display_name": "Chung, Soon-Jo" }, { "name": { "family": "Hunt", "given": "Melany L." }, "id": "Hunt-M-L", "orcid": "0000-0001-5592-2334", "role": "member", "display_name": "Hunt, Melany L." }, { "name": { "family": "Ehlmann", "given": "Bethany L." }, "id": "Ehlmann-B-L", "orcid": "0000-0002-2745-3240", "role": "member", "display_name": "Ehlmann, Bethany L." } ], "option_major": [ "mecheng" ], "doi": "10.7907/4csx-4636", "abstract": "Recent missions to small bodies in the past decade (e.g., Rosetta, Hayabusa 2, and OSIRIS-REx) have reshaped our understanding of small bodies and inspired new, more-capable future missions. Despite the high demand for more missions, large uncertainties in small body properties make missions challenging. Recent work in stochastic optimal control can ensure safety in the face of uncertainty in state, constraints, and dynamics. These stochastic optimal controllers require a model of the underlying dynamics, which is difficult for proximity maneuvers and landing around small bodies. Shape models and finite element-like models are the state-of-the-art for high-fidelity gravity models, but they are computationally expensive and do not readily incorporate onboard data. No gravity model yet exists that can use short-horizon position and acceleration data from recent trajectories onboard in safety-critical autonomous proximity maneuvers and landing. Therefore, we propose a new trajectory-only learning-based method to develop a gravity model. We consider three learning frameworks: Gaussian Process Models, Neural Networks, and Physics-Informed Neural Networks. For each framework, we assess the benefits, computational costs, and limitations of the framework. We found that the Gaussian Process Model generally outperforms the other frameworks in cases of moderate uncertainty. As the uncertainty declines or the data is sufficiently filtered, Neural Networks with spectral normalization provide more accurate gravity models and are computationally cheaper to evaluate. Lastly, we reflect on the methods in this thesis and recommend possible problem reformulations for future research.
" }, { "name": "Porter, Tara S.", "degree": "Senior Thesis", "year": "2021", "title": "Stabilization of Brain-Machine Interface Systems via Alignment to Baseline", "advisor": "Emami, Azita", "url": "https://resolver.caltech.edu/CaltechTHESIS:06102021-045007834", "creators": [ { "name": { "family": "Porter", "given": "Tara S." }, "id": "Porter-Tara-S", "orcid": "0000-0002-2145-9019", "display_name": "Porter, Tara S." } ], "advisors": [ { "name": { "family": "Emami", "given": "Azita" }, "id": "Emami-A", "orcid": "0000-0002-6945-9958", "role": "advisor", "display_name": "Emami, Azita" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "eleceng" ], "doi": "10.7907/y1jt-b620", "abstract": "Research in the brain-machine interface has the potential to transform the lives of individuals with limited motor capabilities to allow for greater independence. By directly accessing signals in the brain, it is possible to train a decoder to identify intended motion and allow the user to control a prosthetic limb or computer cursor by simply thinking about the motion. However, neural data recorded from implanted electrodes is highly unstable over time and across multiple sessions, leading to a severe drop in decoding performance as the test data becomes more distant from the data on which the decoder was trained. Here, we investigate a method to stabilize neural spike data from human trials of a center-out cursor control task before it is passed to a linear decoder, using the techniques of factor analysis and Procrustes alignment. We find that for highly variable human neural data from experiment dates that are far apart, the method does not help the decoder better predict cursor kinematics. However, when factor analysis weights are averaged over multiple baseline days, the performance of the decoder significantly increases with Procrustes alignment, which gives a promising method to limit recalibration and retraining of neural decoders by prolonging their higher accuracy performance over time." }, { "name": "Cui, Can (Sunny)", "degree": "Senior Thesis", "year": "2020", "title": "Optimizing Deep Neural Networks for Single Cell Segmentation", "advisor": "Van Valen, David A.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06052020-210957529", "creators": [ { "name": { "family": "Cui", "given": "Can (Sunny)" }, "id": "Cui-Can-Sunny", "orcid": "0000-0003-4665-0626", "display_name": "Cui, Can (Sunny)" } ], "advisors": [ { "name": { "family": "Van Valen", "given": "David A." }, "id": "Van-Valen-D", "orcid": "0000-0001-7534-7621", "role": "advisor", "display_name": "Van Valen, David A." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "eleceng" ], "doi": "10.7907/030b-pm67", "abstract": "Analysis of live-cell imaging experiments at the resolution of single cells provides exciting insights into the inner workings of biological systems. Advances in biological imaging and computer vision allow for segmentation of natural images with a high degree of accuracy. However, automation of the segmentation pipeline at the single cell resolution remains a challenging task. Complex deep learning models require large, well-annotated datasets that are rarely available in biology. In this research, we explore various methods that optimize state of the art deep learning frameworks, despite limited resources. We trained a large permutation of models to quantify their capacity and to measure the effects of temporal information, spatial awareness and transfer learning on model performance. We find that, although training set size is most impactful in improving model accuracy, we can leverage techniques like spatial awareness and transfer learning to compromise for the lack of data. These insights show that, with an abundance of data, light-weight models can be as performant as their heavy-weight counterparts in cellular analysis. " }, { "name": "Salzman, Erika Emmanuelle", "degree": "Senior Thesis", "year": "2020", "title": "Functional Acrylate Resins for Shape Memory Polymer Microarchitectures", "advisor": "Greer, Julia R.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06032020-220309895", "creators": [ { "name": { "family": "Salzman", "given": "Erika Emmanuelle" }, "id": "Salzman-Erika-Emmanuelle", "orcid": "0000-0002-2995-7864", "display_name": "Salzman, Erika Emmanuelle" } ], "advisors": [ { "name": { "family": "Greer", "given": "Julia R." }, "id": "Greer-J-R", "role": "advisor", "display_name": "Greer, Julia R." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "matsci" ], "doi": "10.7907/8870-1x03", "abstract": "Shape memory polymers (SMPs) are materials that can undergo programmable shape change in response to a specific stimulus. The ability to undergo this reliable, three-dimensional shape change makes SMPs promising smart materials for applications like biomedical stents and sutures. However, to access areas like blood vessels in the eye, these materials must be fabricated with micron or submicron resolution. In this work, benzyl methacrylate-based, heat-responsive SMP microstructures were fabricated using two-photon lithography in a variety of three-dimensional designs. The effects of different fabrication conditions on the structures were studied, and Raman spectroscopy was used to probe network properties, including degree of polymerization.
\r\n\r\nThe resin was also chemically functionalized prior to polymerization with BOC-protected amine groups via the thiol-Michael addition reaction, which allows for attachment of other useful functional groups to the surface of the structures. This chemistry was utilized for attachment of a dye as well as gold nanoparticles. When exposed to laser light, these nanoparticles can undergo localized surface plasmon resonance and serve as heat generators. The theoretical feasibility of using this heating technique to induce shape change in SMP microstructures is examined in this work.
" }, { "name": "Schwacke, Miranda Lee", "degree": "Senior Thesis", "year": "2020", "title": "Mechanical Properties and Characterization of Nanocrystalline Ni and Ni Solid Solutions", "advisor": "Greer, Julia R.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06122020-164731280", "creators": [ { "name": { "family": "Schwacke", "given": "Miranda Lee" }, "id": "Schwacke-Miranda-Lee", "display_name": "Schwacke, Miranda Lee" } ], "advisors": [ { "name": { "family": "Greer", "given": "Julia R." }, "id": "Greer-J-R", "role": "advisor", "display_name": "Greer, Julia R." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "matsci" ], "doi": "10.7907/j8rq-5c26", "abstract": "In this work we investigate the mechanical properties of nanocrystalline Ni and Ni solid solutions made by both traditional fabrication methods (through a literature review) and by a newly developed chemical-derivation method (through experimental characterization and nanoindentaiton testing). Chapter 1 consists of a review of the current literature on nanocrystalline Ni. It focuses specifically on\r\nhow the grain size of these materials is related to hardness through the Hall-Petch relationship and at grain sizes past the Hall-Petch breakdown. Given the number of apparent deviations from the Hall-Petch relationship found in the literature, in Chapter 2 we consider factors other than grain size which can impact hardness, including additives, annealing, and texture. Chapter 3 provides a description of\r\nour own experimental methods and results, including sample fabrication, grain size measurement, and nanoindentation. The hardness and reduced modulus of our nanocrystalline Ni samples are calculated to be 56 MPa and 1.76 GPa, respectively. These values are very low compared to what is described in the literature. Chapter 4 presents models for the hardness and Young\u2019s modulus of nanocrystalline materials as functions of porosity, impurity content, and other factors which might cause anomalously low values. However, we find that these models are unable to account for the values we have observed. Chapter 5 includes a discussion of future work which should be done in order to better understand the deformation occurring in chemically-derived nanocrystalline Ni and how it differs from what is described in the literature." }, { "name": "Lymperopoulos-Bountalis, Filippos", "degree": "Senior Thesis", "year": "2019", "title": "Town Meeting: A Representative but Non-Sovereign Institution", "advisor": "Dykstra, Maura", "url": "https://resolver.caltech.edu/CaltechTHESIS:07252019-051751946", "creators": [ { "name": { "family": "Lymperopoulos-Bountalis", "given": "Filippos" }, "id": "Lymperopoulos-Bountalis-Filippos", "orcid": "0000-0002-7122-7793", "display_name": "Lymperopoulos-Bountalis, Filippos" } ], "advisors": [ { "name": { "family": "Dykstra", "given": "Maura" }, "id": "Dykstra-M", "orcid": "0000-0001-6036-6440", "role": "advisor", "display_name": "Dykstra, Maura" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "history", "mecheng" ], "doi": "10.7907/AX73-H321", "abstract": "Questions of democracy are fundamental for modern society. One of the main distinctions made in the study of democracy is between direct and representative democracy. While most democratic institutions today are representative, the roots of democracy lie in direct democracy, a system in which citizens vote directly on the issues rather than on candidates who will then make the decisions. One of the most historically significant institutions in the area of direct democracy, especially in the American tradition, is the town meeting. Unfortunately, most of the discussion on the town meeting has focused on the question of representation (for example attendance rates at meetings) resulting in a substitution of a broad discussion on democracy with a narrow discussion on representation. The aim of this thesis is not only to illustrate this issue, but also to indicate how the addition of another axis of analysis, power-external/sovereignty, can untangle some of the confusing aspects of the existing narratives regarding the town meeting. The thesis draws upon a variety of documents, such as 17th century town meeting records, the writings of Thomas Jefferson, a 20th century radio show, and present day news articles, in order to aid in the reconceptualization of core issues such as power and representation, as well as to provide new insights in topics such as the use of direct democracy for purposes of political education. The hope is to inspire more advances in our understanding of the limitations and shortcomings of our current framework of analysis for the town meeting, as well as to introduce different perspectives of analysis which, in combination with representation and power, can provide a more holistic understanding of the town meeting institution.
" }, { "name": "Rimoli Assumpcao, Daniel", "degree": "Senior Thesis", "year": "2019", "title": "Landau Damping Induced Limits in Nanogap Metal-Insulator-Metal Plasmonic Waveguides and Cavities", "advisor": "Choo, Hyuck", "url": "https://resolver.caltech.edu/CaltechTHESIS:07142019-013642871", "creators": [ { "name": { "family": "Rimoli Assumpcao", "given": "Daniel" }, "id": "Daniel-Assumpcao", "orcid": "0000-0002-0374-9901", "display_name": "Rimoli Assumpcao, Daniel" } ], "advisors": [ { "name": { "family": "Choo", "given": "Hyuck" }, "id": "Choo-Hyuck", "role": "advisor", "display_name": "Choo, Hyuck" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "eleceng" ], "doi": "10.7907/HVA5-G915", "abstract": "Plasmonic structures permit the focusing of light into volumes far below the diffraction limit. In particular Metal-Insulator-Metal (MIM) gap plasmonic structures can reach nanoscale energy confinement if the gap is sufficiently miniaturized. Under classical models, gap plasmonics can achieve indefinite confinement, down to the single atom level. However, these classical models fail to consider quantum effects that occur as the confinement approaches the single nanometer level. Recently, it has been demonstrated that Landau Damping, the absorption of highly confined plasmonic energy, is the dominant effect in highly confined MIM devices until the tunneling regime is reached. However, the effects of Landau Damping on MIM gap devices are poorly understood. In this work, we analyze the effects of Landau Damping on MIM gap devices, specifically MIM waveguides and cavities. It is found that in waveguides, Landau Damping does not limit the confinement but does limit the maximum propagation length achievable. Moreover, in cavity structures, Landau Damping causes the Quality Factor to drop significantly as the gap is further miniaturized. In terms of quantum optics applications, this causes the radiative spontaneous emission enhancement to actually decrease as the gap is miniaturized sufficiently and a saturation of the coupling-loss ratio limiting the achievement of strong coupling. These effects will limit the possibilities for high performance nanogap plasmonic devices.
" }, { "name": "Sreedhar, Kavya", "degree": "Senior Thesis", "year": "2019", "title": "Next Generation Fast Shutter System for LIGO", "advisor": "Abbott, Richard", "url": "https://resolver.caltech.edu/CaltechTHESIS:06122019-230500900", "creators": [ { "name": { "family": "Sreedhar", "given": "Kavya" }, "id": "Sreedhar-Kavya", "orcid": "0000-0002-8456-6313", "display_name": "Sreedhar, Kavya" } ], "advisors": [ { "name": { "family": "Abbott", "given": "Richard" }, "id": "Abbott-Richard", "role": "advisor", "display_name": "Abbott, Richard" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "eleceng" ], "doi": "10.7907/PXGW-QF88", "abstract": "The proposal for the next generation Fast Shutter system intended to replace the current electromagnetic system used to block an optical pulse that is part of the LIGO observational setup is presented and discussed. The current system setup, problems solved with the new setup, and experiments guiding the new proposal design are detailed along with future work remaining to verify the operation of the next generation Fast Shutter system before it is used in LIGO's observatories.
\r\n \r\nThis system is an electro-mechanical device consisting of two coils of electrically conducting wires and a payload made up of two magnets of opposite polarity configured to move between the upper and lower parts of the device. The mirror is attached to the magnet payload and is used to reflect optical pulses. When a current is applied to the coils, the magnets and attached mirror can move vertically relative to the coils due to the Lorentz force from the current in the coils acting on the magnets. The system can be operated in air or in a vacuum environment over a wide range of temperature and cleanliness requirements.
\r\n \r\nThis system offers a novel and robust solution compared to LIGO's previously patented electro-magnetic ultra-fast shutter due to the design of a moving payload consisting of magnets and a mirror with no wires attached, compared to the prior design consisting of a moving coil requiring electrical attachment. As a result, this system avoids the failure mode associated with wire fatigue caused by repeated flexure of the coil attachment wires. With stationary coils, this system uses permanent magnets for the upward propulsion of the payload. Eddy current damping provided by copper interacting with the payload magnets is included to damp the oscillatory transient response of the payload. This newly designed system achieves the same critical performance specifications as the previously patented ultra-fast mechanical shutter, while being physically smaller, cheaper to build, and vastly more reliable.
" }, { "name": "Moorthy, Aadith", "degree": "Senior Thesis", "year": "2018", "title": "Theoretical and Experimental Study of Pressure Hysteresis in the Palladium Hydride Phase Transformation", "advisor": "Fultz, Brent T.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06072018-182938429", "creators": [ { "name": { "family": "Moorthy", "given": "Aadith" }, "id": "Moorthy-Aadith", "display_name": "Moorthy, Aadith" } ], "advisors": [ { "name": { "family": "Fultz", "given": "Brent T." }, "id": "Fultz-B-T", "role": "advisor", "display_name": "Fultz, Brent T." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "matsci" ], "doi": "10.7907/mems-1g53", "abstract": "A unique phenomenon occurring with metal hydride systems that presents a loss in hydrogen storage efficiency and has received little scientific attention is the hysteresis behavior observed during H2 absorption and desorption. As an ambient H2 pressure is introduced into a metal hydride, the material undergoes a phase transformation from a hydrogen-poor phase to a hydrogen-rich phase during absorption and the reverse during desorption. However, the phase transformation is hysteretic as it occurs at a much higher H2 pressure for absorption than for desorption.
\r\n\r\nIn this work, the thermodynamics of the metal hydride phase transformation with hydrogen uptake are experimentally studied using the palladium-hydride system with in-situ x-ray diffraction. The in-situ x-ray diffraction has enabled the study of the thermodynamic evolution of the microstructure of the palladium through lattice parameters, phase fractions, strain analyses and other information. The diffraction data has then been compared to the predictions from existing theories on hysteresis in metal hydrides, such as the Schwarz-Khachaturyan and Flanagan-Clewley theories. Finally, these theories are extended and combined to form a new general theory of metal hydride phase transformation thermodynamics that incorporates new attributes of importance for practical metal hydride systems, such as phase interface coherency and changes in dislocation formation energies due to work hardening. This new theory is very effective in explaining the prominent trends in the experimental data and provides a highly general approach for the analysis of phase transformations from hydriding in real metals.
" }, { "name": "Periyakoil, Preethi Kasthuri", "degree": "Senior Thesis", "year": "2018", "title": "Utilizing Machine Learning Techniques to Rapidly Identify MUC2 Expression in Colon Cancer Tissues", "advisor": "Yue, Yisong", "url": "https://resolver.caltech.edu/CaltechTHESIS:08232018-131754063", "creators": [ { "name": { "family": "Periyakoil", "given": "Preethi Kasthuri" }, "id": "Periyakoil-Preethi-Kasthuri-", "display_name": "Periyakoil, Preethi Kasthuri" } ], "advisors": [ { "name": { "family": "Yue", "given": "Yisong" }, "id": "Yue-Yisong", "role": "advisor", "display_name": "Yue, Yisong" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "compsci" ], "doi": "10.7907/sapn-r691", "abstract": "Colorectal cancer is the third-most common form of cancer among American men and women. Like most tumors, colon cancer is sustained by a subpopulation of \u201cstem cells\u201d that possess the ability to self-renew and differentiate into more specialized cell types. It would be useful to detect stem cells in images of colon cancer tissue, but the first step in being able to do so is to know what genes are expressed in the stem cells and how to detect their expression pattern from the tissue images. Machine learning (ML) is a powerful tool that is widely used in biological research as a novel and innovative technique to facilitate rapid diagnosis of cancer. The current study demonstrates the feasibility and effectiveness of using ML techniques to rapidly detect the expression of the gene MUC2 (mucin 2) in colon cancer tissue images. We analyzed histological images of colon cancer and segmented the nuclei to look for features (area, perimeter, eccentricity, compactness, etc.) that correlate with high or low levels of MUC2. Grid search was then run on this data set to tune the hyper-parameters, and the following models were tested as potential classifiers: random forest, gradient boosting, decision trees with AdaBoost, and support vector machines. Of all of the tested models, it was found that the random forest classifier (f1 score of 0.71) and the gradient boosting classifier (f1 score of 0.72) were able to predict the output label most accurately. Under certain conditions, we have identified four features that have predictive capabilities. Predicting individual gene expression with machine learning is the first step in detecting genes that are specific to cancer stem cells in the early stages of cancer, while there is still hope for a cure." }, { "name": "Bischann, Moriah Nicole", "degree": "Senior Thesis", "year": "2017", "title": "Transverse Photonic Doppler Velocimetry for Plate Impact Experiments", "advisor": "Ravichandran, Guruswami", "url": "https://resolver.caltech.edu/CaltechTHESIS:06012017-131024630", "creators": [ { "name": { "family": "Bischann", "given": "Moriah Nicole" }, "id": "Bischann-Moriah-Nicole", "orcid": "0000-0002-6674-5158", "display_name": "Bischann, Moriah Nicole" } ], "advisors": [ { "name": { "family": "Ravichandran", "given": "Guruswami" }, "id": "Ravichandran-G", "role": "advisor", "display_name": "Ravichandran, Guruswami" } ], "option_major": [ "matsci" ], "doi": "10.7907/Z9GB224C", "abstract": "High-pressure shock waves propagate in materials when automobiles collide, projectiles impact against bunkers, and mining charges detonate beneath Earth's surface. It is difficult to quantify the behavior of materials experiencing such sudden and high pressures. Specialized interferometry techniques have enabled the study of rapid, high-strain-rate deformation during controlled plate impact testing.
\r\n\r\nTransverse motion during plate impact experiments is currently measured with the transverse displacement interferometer (TDI). However, the TDI does not take advantage of modern telecommunications technology and data analysis techniques that allow for the measurement of high velocities (in the km/s range) with fine time resolution. We designed and developed a transverse photonic Doppler velocimetry (TPDV) technique for plate impact experiments based entirely on fiber optic components. The TPDV system uses light diffracted from a grating to capture transverse motion. This signal is frequency upshifted to achieve more fringes per unit time. Data is analyzed using spectral analysis techniques to detect micrometer displacements on a nanosecond to microsecond timescale.
\r\n\r\nWe demonstrated the TPDV technique's capabilities with normal impact of single crystalline y-cut alpha-quartz against borosilicate. We simultaneously collected photonic Doppler velocimetry (PDV) measurements of longitudinal displacements. Finally, we compared our longitudinal and transverse experimental results to theoretical calculations. Our data's orthogonal velocity jumps showed that the TPDV technique accurately detected transient velocities and the magnitudes of longitudinal and shear waves.
\r\n\r\nOur TPDV technique will facilitate the study of deformation and failure of materials during normal and pressure-shear plate impact. Comprehending shock-wave dominated deformation in materials is important for the design of aerospace structures, understanding planetary impact, and creating shock-mitigating materials.
" }, { "name": "Shah, Parth", "degree": "Senior Thesis", "year": "2017", "title": "Heading Estimation via Sun Sensing for Autonomous Navigation", "advisor": "Burdick, Joel Wakeman", "url": "https://resolver.caltech.edu/CaltechTHESIS:06142017-153929873", "creators": [ { "name": { "family": "Shah", "given": "Parth" }, "id": "Shah-Parth", "orcid": "0000-0003-0780-0847", "display_name": "Shah, Parth" } ], "advisors": [ { "name": { "family": "Burdick", "given": "Joel Wakeman" }, "id": "Burdick-J-W", "role": "advisor", "display_name": "Burdick, Joel Wakeman" } ], "committee": [ { "name": { "family": "Blanquart", "given": "Guillaume" }, "id": "Blanquart-G", "role": "chair", "display_name": "Blanquart, Guillaume" }, { "name": { "family": "Burdick", "given": "Joel Wakeman" }, "id": "Burdick-J-W", "role": "member", "display_name": "Burdick, Joel Wakeman" } ], "option_major": [ "mecheng" ], "doi": "10.7907/Z9BG2M1S", "abstract": "In preparation for the mission to Mars in 2020, NASA JPL and Caltech have been exploring the potential of sending a scout robot to accompany the new rover. One of the leading candidates for this scout robot is a lightweight helicopter that can fly every day for ~1 to 3 minutes. Its findings would be critical in the path planning for the rover because of its ability to see over and round local terrain elements. The inconsistent Mars magnetic field and GPS-denied environment would require the navigation system of such a vehicle to be completely overhauled. In this thesis, we present a novel technique for heading estimation for autonomous vehicles using sun sensing via fisheye camera. The approach results in accurate heading estimates within 2.4\u00b0 when relying on the camera alone. If the information from the camera is fused with our sensors, the heading estimates are even more accurate. While this does not yet meet the desired error bound, it is a start with the critical flaws in the algorithm already identified in order to improve performance significantly. This lightweight solution however shows promise and does meet the weight constraints for the 1 kg Mars 2020 Helicopter Scout.
" }, { "name": "Fan, Boyu", "degree": "Senior Thesis", "year": "2015", "title": "Fluid-Structure Interactions of Inverted Leaves and Flags", "advisor": "Gharib, Morteza", "url": "https://resolver.caltech.edu/CaltechTHESIS:10272015-171407458", "creators": [ { "name": { "family": "Fan", "given": "Boyu" }, "id": "Fan-Boyu", "display_name": "Fan, Boyu" } ], "advisors": [ { "name": { "family": "Gharib", "given": "Morteza" }, "id": "Gharib-M", "orcid": "0000-0003-0754-4193", "role": "advisor", "display_name": "Gharib, Morteza" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "mecheng" ], "doi": "10.7907/Z9GQ6VPC", "abstract": "Interactions between fluid flows and elastic bodies are ubiquitous in nature. One such phenomena that is encountered on a daily basis is the flapping and fluttering of leaves in the wind. The fluid-structure interaction that governs the physics of a leaf in the wind is poorly understood at best and has potential applications in biomechanics, vehicle design, and energy conversion. We build upon previous work on the flapping dynamics of inverted flags, which are cantilevered elastic sheets with free leading edge and fixed trailing edge that display unique large amplitude oscillatory behaviors. We model a leaf in the laboratory using modified inverted flags, experimentally probing the governing parameters behind leaf fluttering as well as shedding light on the physics behind the inverted flag phenomena. The behavior of these \"inverted leaves\" studied here display sensitive dependence on two biomechanically relevant parameters, stem-to-leaf rigidity and stem-to-leaf length. In addition, leaves on a tree are not often found alone. We seek to understand the complex interactions of multiple fluttering and flapping leaves by way of examining the interactions between pairs of inverted flags. Coupling through their flow fields, pairs of inverted flags exhibit striking emergent phenomena. We report these observed dynamical behaviors and the conditions upon which they arise." }, { "name": "Huang, Tiffany Amy", "degree": "Senior Thesis", "year": "2014", "title": "Convex Model Predictive Control for Vehicular Systems", "advisor": "Burdick, Joel Wakeman", "url": "https://resolver.caltech.edu/CaltechTHESIS:06052014-200112345", "creators": [ { "name": { "family": "Huang", "given": "Tiffany Amy" }, "id": "Huang-Tiffany-Amy", "display_name": "Huang, Tiffany Amy" } ], "advisors": [ { "name": { "family": "Burdick", "given": "Joel Wakeman" }, "id": "Burdick-J-W", "orcid": "0000-0002-3091-540X", "role": "advisor", "display_name": "Burdick, Joel Wakeman" } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "mecheng" ], "doi": "10.7907/PNN7-SC35", "abstract": "In this work, the author presents a method called Convex Model Predictive Control (CMPC) to control systems whose states are elements of the rotation matrices SO(n) for n = 2, 3. This is done without charts or any local linearization, and instead is performed by operating over the orbitope of rotation matrices. This results in a novel model predictive control (MPC) scheme without the drawbacks associated with conventional linearization techniques such as slow computation time and local minima. Of particular emphasis is the application to aeronautical and vehicular systems, wherein the method removes many of the trigonometric terms associated with these systems\u2019 state space equations. Furthermore, the method is shown to be compatible with many existing variants of MPC, including obstacle avoidance via Mixed Integer Linear Programming (MILP)." }, { "name": "Hoglen, Nerissa Emmy Graetz", "degree": "Senior Thesis", "year": "2013", "title": "Charles I: Unhero of Royalist Poetry", "advisor": "Haugen, Kristine L.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06092013-095317436", "creators": [ { "name": { "family": "Hoglen", "given": "Nerissa Emmy Graetz" }, "id": "Hoglen-Nerissa-Emmy-Graetz", "display_name": "Hoglen, Nerissa Emmy Graetz" } ], "advisors": [ { "name": { "family": "Haugen", "given": "Kristine L." }, "id": "Haugen-K-L", "role": "advisor", "display_name": "Haugen, Kristine L." } ], "committee": [ { "name": { "family": "Gilmartin", "given": "Kevin M." }, "id": "Gilmartin-K-M", "role": "chair", "display_name": "Gilmartin, Kevin M." } ], "option_major": [ "cns" ], "doi": "10.7907/3QHF-E532", "abstract": "During the English Civil War, Charles I appeared as a character in Royalist poetry, both directly and allegorically. These depictions drew on ancient Roman epic poems, particularly Lucan\u2019s De Bello Civili, in their treatment of the subject matter of civil war and Charles as an epic hero. Though the authors of these poems supported Charles, their depictions of him and his reign reveal anxiety about his weakness as a ruler. In comparison to the cults of personality surrounding his predecessors and the heroes of De Bello Civili, his cult appears bland and forced. The lack of enthusiasm surrounding Charles I may help to explain his downfall at the hands of his Parliamentarian opponents.\r\n\u2003\r\n" }, { "name": "Rosenberg, Robert Alan", "degree": "Senior Thesis", "year": "2011", "title": "The Impact of Surface Chemistry on Photoelectrochemical Device Characteristics", "advisor": "Lewis, Nathan Saul; Grimm, Ron L.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06032011-161436489", "creators": [ { "name": { "family": "Rosenberg", "given": "Robert Alan" }, "id": "Rosenberg-Robert-Alan", "display_name": "Rosenberg, Robert Alan" } ], "advisors": [ { "name": { "family": "Lewis", "given": "Nathan Saul" }, "id": "Lewis-N-S", "orcid": "0000-0001-5245-0538", "role": "advisor", "display_name": "Lewis, Nathan Saul" }, { "name": { "family": "Grimm", "given": "Ron L." }, "id": "Grimm-R-L", "role": "co-advisor", "display_name": "Grimm, Ron L." } ], "committee": [ { "name": { "family": "Lewis", "given": "Nathan Saul" }, "id": "Lewis-N-S", "orcid": "0000-0001-5245-0538", "role": "chair", "display_name": "Lewis, Nathan Saul" }, { "name": { "family": "Troian", "given": "Sandra M." }, "id": "Troian-S-M", "orcid": "0000-0003-1224-6377", "role": "member", "display_name": "Troian, Sandra M." }, { "name": { "family": "Painter", "given": "Oskar J." }, "id": "Painter-O", "orcid": "0000-0002-1581-9209", "role": "member", "display_name": "Painter, Oskar J." } ], "option_major": [ "appliedphys" ], "doi": "10.7907/TW3G-C242", "abstract": "Varying degrees of partial methylation are performed on the (111) surface of p-type Si in order to investigate the role of mixed surface functionality on the device\u2019s overall properties. Current-voltage characteristics are acquired in nonaqueous regenerative photoelectrochemical cells with a variety of one-electron redox species. P-type and p/n+ electrodes are evaluated, allowing comparisons between devices where the energy barrier is set by the semiconductor-liquid interface and devices where the energy barrier is set by the buried junction with the heavily doped emitter layer. In contrast to fully methylated or entirely unprotected surfaces, the intermediately methylated devices exhibit mixed monolayers with a disparity in barrier height. Charge transfer across these interfaces is studied, and effects such as pinch-off are considered in the search for a threshold surface composition for acceptable device performance. " }, { "name": "Cullina, Daniel Francis", "degree": "Senior Thesis", "year": "2009", "title": "Searching for Minimum Storage Regenerating Codes", "advisor": "Ho, Tracey C.", "url": "https://resolver.caltech.edu/CaltechTHESIS:01262011-102713095", "creators": [ { "name": { "family": "Cullina", "given": "Daniel Francis" }, "id": "Cullina-Daniel-Francis", "orcid": "0000-0002-7471-2102", "display_name": "Cullina, Daniel Francis" } ], "advisors": [ { "name": { "family": "Ho", "given": "Tracey C." }, "id": "Ho-Tracey", "role": "advisor", "display_name": "Ho, Tracey C." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "eleceng" ], "doi": "10.7907/ATJY-BT03", "abstract": "Regenerating codes allow distributed storage systems to recover from the loss of a storage node while transmitting the minimum possible amount of data across the network. We search for examples of Minimum Storage Regenerating Codes. To exhaustively search the space of potential codes, we reduce the potential search space in several ways. We impose an additional symmetry condition on codes that we consider. We specify codes in a simple alternative way, using additional recovered coefficients rather than transmission coefficients. We place codes into equivalence classes to avoid redundant checking. We find MSR codes for the parameters n = 5 and k = 3 in various fields. We demonstrate that it is possible for such codes to be composed of vectors in general position." }, { "name": "Jewell, Joseph Stephen", "degree": "Senior Thesis", "year": "2004", "title": "Violence in the Medieval Church before the First Crusade", "advisor": "Brown, Warren C.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06162014-194836973", "creators": [ { "name": { "family": "Jewell", "given": "Joseph Stephen" }, "id": "Jewell-Joseph-Stephen", "orcid": "0000-0002-4047-9998", "display_name": "Jewell, Joseph Stephen" } ], "advisors": [ { "name": { "family": "Brown", "given": "Warren C." }, "id": "Brown-Warren-C", "role": "advisor", "display_name": "Brown, Warren C." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "aeronautics", "history" ], "doi": "10.7907/33km-kt20", "abstract": "The attitude of the medieval church towards violence before the First Crusade in 1095 underwent a significant institutional evolution, from the peaceful tradition of the New Testament and the Roman persecution, through the prelate-led military campaigns of the Carolingian period and the Peace of God era. It would be superficially easy to characterize this transformation as the pragmatic and entirely secular response of a growing power to the changing world. However, such a simplification does not fully do justice to the underlying theology. While church leaders from the 5th Century to the 11th had vastly different motivations and circumstances under which to develop their responses to a variety of violent activities, the teachings of Augustine of Hippo provided a unifying theme. Augustine\u2019s just war theology, in establishing which conflicts are acceptable in the eyes of God, focused on determining whether a proper causa belli or basis for war exists, and then whether a legitimate authority declares and leads the war. Augustine masterfully integrated aspects of the Old and New Testaments to create a lasting and compelling case for his definition of justified violence. Although at different times and places his theology has been used to support a variety of different attitudes, the profound influence of his work on the medieval church\u2019s evolving position on violence is clear." }, { "name": "Armond, Michelle Elle", "degree": "Senior Thesis", "year": "2000", "title": "Legal Dimensions of the Chinese Experience in Los Angeles, 1860-1880", "advisor": "Deverell, William F.", "url": "https://resolver.caltech.edu/CaltechTHESIS:01222014-101324309", "creators": [ { "name": { "family": "Armond", "given": "Michelle Elle" }, "id": "Armond-Michelle-Elle", "display_name": "Armond, Michelle Elle" } ], "advisors": [ { "name": { "family": "Deverell", "given": "William F." }, "id": "Deverell-W-F", "role": "advisor", "display_name": "Deverell, William F." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "eleceng", "histsci" ], "doi": "10.7907/8Q9B-F003", "abstract": "On October 24, 1871, a massacre of eighteen Chinese in Los Angeles brought the small southern California settlement into the national spotlight. Within a few days, news of this \u201cnight of horrors\u201d was reported in newspapers across the country. This massacre has been cited in Asian American narratives as the first documented outbreak of ethnic violence against a Chinese community in the United States. This is ironic because Los Angeles\u2019 small population has generally placed it on the periphery in historical studies of the California anti-Chinese movement. Because the massacre predated Los Angeles\u2019 organized Chinese exclusion movements of the late 1870s, it has often been erroneously dismissed as an aberration in the history of the city.
\r\n\r\nThe violence of 1871 was an outburst highlighting existing community tensions that would become part of public debate by decade\u2019s close. The purpose of this study is to insert the massacre into a broader context of anti-Chinese sentiments, legal discrimination, and dehumanization in nineteenth century Los Angeles. While a second incident of widespread anti-Chinese violence never occurred, brutal attacks directed at Chinese small businessmen and others highlighted continued community conflict. Similarly, economic rivalries and concerns over Chinese prostitution that underlay the 1871 massacre were manifest in later campaigns of economic discrimination and vice suppression that sought to minimize Chinese influence within municipal limits. An analysis of the massacre in terms of anti-Chinese legal, social and economic strategies in nineteenth-century Los Angeles will elucidate these important continuities.
" }, { "name": "Tkacenko, Andre", "degree": "Senior Thesis", "year": "1999", "title": "The Fractional Discrete Fourier Transform", "advisor": "McEliece, Robert J.; Vaidyanathan, P. P.", "url": "https://resolver.caltech.edu/CaltechTHESIS:06272025-213209576", "creators": [ { "name": { "family": "Tkacenko", "given": "Andre" }, "id": "Tkacenko-Andre", "display_name": "Tkacenko, Andre" } ], "advisors": [ { "name": { "family": "McEliece", "given": "Robert J." }, "id": "McEliece-R-J", "role": "advisor", "display_name": "McEliece, Robert J." }, { "name": { "family": "Vaidyanathan", "given": "P. P." }, "id": "Vaidyanathan-P-P", "orcid": "0000-0003-3003-7042", "role": "co-advisor", "display_name": "Vaidyanathan, P. P." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "eleceng" ], "doi": "10.7907/w1qa-g468", "abstract": "A fractional version of the Discrete Fourier Transform or DFT, denoted by the Fractional Discrete Fourier Transform or FDFT for short, is discussed here. First, results of a fractional version of the continuous-time Fourier Transform or CTFT are explored and then parallels are made between the DFT and the CTFT. Using the method of spectral decomposition [1], an expression for the FDFT is then derived which satisfies properties analogous to the fractional CTFT. Afterwards, properties of the FDFT are discovered and proven, and an example of an FDFT pair is given. Finally, various applications of the FDFT in signal processing in\r\nareas such as allpass filter networks and the M-channel maximally decimated filter bank are discussed." }, { "name": "Liew, Boon-Khim", "degree": "Senior Thesis", "year": "1985", "title": "Study of Solid-Phase Reactions of Metals on GaAs", "advisor": "Nicolet, Marc-Aurele", "url": "https://resolver.caltech.edu/CaltechTHESIS:10152014-085619478", "creators": [ { "name": { "family": "Liew", "given": "Boon-Khim" }, "id": "Liew-Boon-Khim", "display_name": "Liew, Boon-Khim" } ], "advisors": [ { "name": { "family": "Nicolet", "given": "Marc-Aurele" }, "id": "Nicolet-M-A", "role": "advisor", "display_name": "Nicolet, Marc-Aurele" } ], "committee": [ { "name": { "family": "Unknown", "given": "Unknown" }, "display_name": "Unknown, Unknown" } ], "option_major": [ "eleceng" ], "doi": "10.7907/pay8-6h38", "abstract": "To make stable and reproducible contacts to GaAs, metals which react with GaAs in the solid-phase should be favored. In this study, contacts formed employing Pd/TiN/Pd/Ag, Pd:Mg/TiN/Pd:Mg/Ag and Ru/TiN/Ru/Ag are studied. The TiN layer is included to investigate its application as diffusion barrier in these metallizations. Contacts to n-GaAs are rectifying and the value of barrier height is modified upon annealing. Contacts to p-GaAs are initially rectifying but exhibit ohmic behaviour after annealing. The modifications in the electrical properties are attributed to the solid-phase reaction of metal and GaAs. The integrity of the contacts relies critically on the success of TiN to prevent the intermixing of Ag overlayer and the underlying layers. At elevated annealing temperatures (450\u00b0C), TiN fails to function as a diffusion barrier. As a result, the properties of the contact deteriorates.\r\n" }, { "name": "Paine, Scott Nelson", "degree": "Senior Thesis", "year": "1984", "title": "High Energy Heavy Ion Beam Enhanced Adhesion of Gold Films to GaAs", "advisor": "Tombrello, Thomas A.", "url": "https://resolver.caltech.edu/CaltechTHESIS:02202018-132931271", "creators": [ { "name": { "family": "Paine", "given": "Scott Nelson" }, "id": "Paine-Scott-Nelson", "orcid": "0000-0003-4622-5857", "display_name": "Paine, Scott Nelson" } ], "advisors": [ { "name": { "family": "Tombrello", "given": "Thomas A." }, "id": "Tombrello-T-A", "role": "advisor", "display_name": "Tombrello, Thomas A." } ], "committee": [ { "name": { "family": "None", "given": "None" }, "display_name": "None, None" } ], "option_major": [ "appliedphys" ], "doi": "10.7907/Z9XD0ZWZ", "abstract": "Improvement of the adhesion of gold films to GaAs substrates by irradiation with a beam of high energy heavy ions was studied by Scotch Tape, scrub, and scratch test methods. Simple measurements of the effect of irradiation on the electrical contact properties of the Au/GaAs interface were also made. Substrate materials were taken from four differently doped GaAs wafers, thus providing a selection of substrate electronic properties.
\r\n\r\nThe results indicate dependence of the ion dose threshold for improved adhesion on the bulk electronic properties of the substrate.
" } ]