VictorJuiz/thesis huggingface dataset:
Precision synthesis with atomic layer deposition for oxygen reduction reaction enhancement

Proton-exchange-membrane fuel cell (PEMFC) technology has progressed significantly over the past few decades for CO2-free energy conversion. However, the energy efficiency of PEMFCs is still far below the thermodynamic limit for numerous reasons. A major cause is the overpotential induced by the sluggish reaction kinetics, especially for oxygen reduction reaction (ORR) on the cathode. To overcome the limitation, efforts have been devoted to developing catalyst material structure engineering to maintain a high intrinsic catalytic activity. In this thesis, I will firstly discuss a strained Pt catalyst with an enhanced catalytic activity for ORR. The catalyst was fabricated by sequential atomic layer deposition(ALD) of cobalt oxide and Pt on the carbon supports, followed by acid leaching that removes almost the entire cobalt oxide template. A compressive strain in the Pt-Pt lattice of the strained catalyst was observed by both extended x-ray absorption fine structure and high-resolution transmission electron microscopy in which negligible Pt-Co interaction is found. Therefore the performance enhancement is mostly attributed to the Pt lattice strain. Secondly I will introduce a precision alloyed Pt-Ti catalyst with a Ti-rich subsurface layer. This catalyst structure was found to have a higher confidence level regarding significant catalytic activity enhancement in density functional theory model. An almost 8-fold activity enhancement compared to Pt ALD catalyst were achieved. Both dynamic secondary ion mass spectroscopy and scanning transmission electron microscopy indicate significant Ti enrichment close to the very surface. Finally, I will describe the fabrication and performance of strained Pt catalyst and Pt-Ti alloy catalyst integrated in membrane electrode assembly(MEA). To further improve the mass activity of the strained Pt catalyst, passivation gas incorporated atomic layer deposition (PALD) was applied. The mass activity was pushed to 0.59A/mg on a Ketjen Black carbon support and even close to 0.8 A/mg on CMK-3. The Ketjen Black-supported catalyst additionally demonstrated impressive durability. For Pt-Ti alloy catalyst, significant performance enhancement especially in specific activity was demonstrated. The temperature-dependent performance was studied and the Pt-Ti alloy catalyst indicates improvement in ORR performance mainly attribute to lowered activation energy barrier

Keywords: Materials Science and Engineering.
Advisor: Prinz F. B.
Clemens B. M. (Bruce M.)
Zheng Xiaolin
The prince of Monaco gave me a present : an ethnographic examination of the governance and social world of the International Olympic Committee

This dissertation examines the interplay between governance, social world, and habitus within the International Olympic Committee (IOC) to understand how decisions are shaped and made. In doing so, it uses the IOC as a privileged site to study a board of directors of a private global organization of import. This study shows that despite an increasing emphasis on the tenets on good governance and transparency, the rule of law, and the idea that the organization operates with all of these practices and principles front of mind, legal-rational governance does not chiefly inform decision making within this organization. This dissertation asks how decisions are really made in the IOC, and how does culture, diverse backgrounds, and disparate access to capital frame power and internal politics within the organization? This dissertation examines an elite, global, private organization at a time of dynamic contestation. It examines how an organization structured around logics of history, cultural capital, and comportment in its membership negotiates calls for good governance. This dissertation argues for the importance of attending to logics in the 'personalistic economy' and in doing so, attests to the ways in which ethnography, through its observational sensitivities and keen eye, can reveal how power actually operates in non-obvious but significant ways. This dissertation demonstrates what an animating force culture and the social world is vis-à-vis governance, even in the most cosmopolitan, modern, Western organizations. It contributes, then, to the growing field of the anthropology of global institutions by highlighting the importance of attending carefully to social worlds in understanding how impactful decisions are made

Keywords: Anthropology.
Advisor: Ebron Paulla A.
Inoue Miyako
Masco Joseph
Yanagisako Sylvia Junko
Projection-based model order reduction and hyperreduction of turbulent flow models

Despite significant advances in simulation-based engineering science in recent decades, time-critical applications struggle to take advantage of high-fidelity, partial differential equation-based computer simulation. This is due to the large processing time and storage requirements associated with large-scale computational models. Projection-based model order reduction (PMOR) methods offer the ability to dramatically reduce this computational cost by generating compact, low-dimensional models for which solutions can be obtained in near real-time while still retaining the accuracy of an associated high-fidelity, high-dimensional model for the time and parameter domain of interest. PMOR is thus an essential technology for the application of model-based control, probabilistic analysis, or design optimization to problems involving increasingly complex engineered systems and physical phenomena. Unfortunately, nonlinear problems, in particular turbulent computational fluid dynamics (CFD) applications, continue to present a number of challenges for constructing stable, accurate, and computationally efficient projection-based reduced order models (PROMs). This thesis addresses some of these challenges, demonstrating PROMs for a number of large-scale, unsteady, turbulent flow applications which showcase the potential of PMOR for nonlinear CFD models with multiscale physics. These results leverage advancements in hyperreduction, a technique for the treatment of nonlinearities in the underlying computational model, to obtain CPU time and wall-clock time speedup factors of several orders of magnitude. This work also presents an investigation of the role of projection in the numerical stability of PMOR for convection-dominated flow problems, ultimately disproving an often-stated claim in the literature with the support of several numerical examples

Keywords: Aeronautics and Astronautics.
Advisor: Farhat Charbel
Alonso Juan José
Lele Sanjiva K. (Sanjiva Keshava)
The proliferation of state and local elections in the United States, 1776-1900

Circa 1787, Americans elected very few state and local officials. Yet, by 1950 they elected far more such officials than any other country. This dissertation presents original data on the nineteenth century reforms that proliferated public offices at the state and county levels. To explain this historical sea change, I present a model of a bargaining problem, faced by all governments, in which leaders must simultaneously fill public offices and fully fund the government's budget. Applying the model to the early American states, I argue that the growth of elective offices at the state and county levels stemmed from elite fears that unitary executive power would fall into the hands of the newly-enfranchised poor. Thus, the main driver of office proliferation was neither Jacksonian Democrats' desire to expand spoils, nor western states' desire to attract labor. I support my thesis mainly using difference-in-difference analyses that compare the timing of "electoralization" to the timing of suffrage expansion from 1776 to 1900

Keywords: Political Science.
Advisor: Cox Gary W.
Brady David W.
Cain Bruce E.
Provenance and sedimentology of the Archean Mapepe Formation, southeastern Barberton Greenstone Belt, South Africa

The 3.5 to 3.2 Ga Barberton Greenstone Belt (BGB), South Africa, offers a view into the surface of the Early Archean Earth. The Fig Tree Group and the Buck Reef Chert of the Onverwacht Group, the subjects of this thesis, are comprised mostly of sedimentary rocks. These rocks still display primary sedimentary structures, and some original geochemical and geochronological signatures are preserved. This study is broken into two parts. The first chapter examines the relationship between three different types of banded cherts seen in the BGB: black and white banded chert (B&W), banded ferruginous chert (BFC), and banded iron formation (BIF). These banded cherts represent a spectrum of related processes and depositional settings. Based on sedimentary structures, petrography, and lithologic associations, we infer that BIF was deposited in deeper water than BFC, and B&W chert was deposited in shallower water than BFC, at depths commonly affected by storms. These relationships suggest that silica was precipitated within the uppermost part of the water column and settled to all depths. Siderite formed mainly in waters of intermediate depth, below the storm agitated surface layer but above the deep basin bottom settings and is a major component of BFC and deeper BIF. A hematite precursor formed in the deepest waters, producing BIF made up of hematite and other components that settled into this setting from shallower sites of precipitation, including silica and siderite. The second chapter is a provenance study of a newly mapped and analyzed structural block, the Mlumati Syncline, and the neighboring blocks in the southeastern part of the BGB. Its proximity and similar stratigraphy to the adjacent Manzimnyama Syncline suggest that these two structural blocks represent parts of the same Archean depositional system. Their similar sandstone petrography, shale geochemistry, and detrital zircon geochronology emphasize the similarity in their source terrains, affirming the hypothesis that they represent parts of a single depositional basin. The sedimentary rocks in these synclines are also compared to those in other structural blocks in the southeastern BGB. The provenance proxies suggest different source terrains, implying the sequences were not part of a single large source, transport, and depositional fairway.

Keywords:  Geological Sciences
School of Earth Energy &amp; Environmental Sciences
Geological Sciences
Archean
banded chert
provenance
Thesis
Advisor: Lowe Donald R.
Graham Stephan
Pulse formation and frequency conversion in dispersion-engineered nonlinear waveguides and resonators

Recent advances in nonlinear photonics have enabled a new class of broadband ultra-stable light sources known as optical frequency combs. These light sources have given rise to an array of new optical devices and systems, spanning applications such as spectroscopy, astronomy, remote sensing, frequency synthesis, attoscience, telecommunications, and optical clockwork. At this time, there are a number of unsolved problems within the field. Optical frequency combs are often constrained to wavelengths within the near-infrared (NIR) due to the limited variety of in mature laser gain media and host glasses, and many applications such as spectroscopy, sensing, and attoscience would benefit from the development of optical frequency combs at longer wavelength ranges such as the mid-infrared (MIR). Furthermore, the generation and stabilization of frequency combs often requires rather complicated nonlinear optical systems, which have prevented these light sources from being used outside of dedicated optics labs. This dissertation considers new approaches to frequency comb generation based on recently discovered nonlinear dynamical processes that occur in quasi-phasematched (QPM) devices with quadratic nonlinearities. A recurring theme is that the interplay of nonlinear optical effects, such as optical parametric amplification and self-phase modulation, with linear optical effects, such as dispersion, can produce qualitatively new dynamical regimes. In many cases, these dynamical regimes exhibit favorable features that potentially solve the problems discussed above. The first half of this thesis considers the pulse formation mechanisms present in optical parametric oscillators (OPOs), and discusses new operating regimes that enable the generation of MIR combs with substantially more bandwidth than the NIR comb used to drive the OPO. These devices can produce few-cycle pulses with conversion efficiencies exceeding 50% while also preserving the coherence of the frequency comb. The latter portion of this thesis studies the dynamics of femtosecond pulses in nanophotonic waveguides. Here, the geometric dispersion associated with sub-wavelength confinement be used to achieve long interaction lengths with femtosecond pulses. Using these effects we are able to achieve saturated SHG with femtojoules of pulse energy, where state-of-the-art devices previously used picojoules. In the limit of phase-mismatched SHG driven with picojoules of pulse energy we observe the formation of a coherent multi-octave supercontinuum comprised of multiple spectrally broadened harmonics. The mechanisms of spectral broadening in this system are shown to be completely unique to dispersion-engineered nanophotonic QPM devices and exhibit a number of desirable features including i) low power requirements, ii) fewer decoherence mechanisms than traditional approaches, and iii) the formation of carrier-envelope-offset beatnotes in the regions of spectral overlap between the harmonics

Keywords: Electrical Engineering.
Purposive visual imitation for learning structured tasks from videos

We are interested in robots that can learn structured tasks automatically from video demonstrations. These structured tasks, like cooking, are hierarchical and often long-horizon. This makes it hard to learn structured tasks purely based on interactions and first-person demonstrations. We advocate the advantages of learning from video demonstrations in this case, which is much easier to collect. The next question is: what exactly should we learn from videos? We propose Purposive Visual Imitation, where we learn the goal and intention of the demonstrator from videos. We show that this leads to stronger generalization than learning low-level trajectories and sequences of actions from the videos. In this dissertation, we will discuss how we can extract task graphs from online instructional videos, and how having such a graphical representation is beneficial for task execution. We will further introduce a motion reasoning framework to extract subgoals from video demonstrations, and how we can use planning to achieve these subgoals based on continuous inputs

Advisor: Li Fei Fei
Brunskill Emma 
Kochenderfer Mykel J.
Quantifying CO2 capillary heterogeneity trapping through experiments, data analysis, and simulation

CO2 geologic storage is an integral part of the climate change solutions in that it allows society to transition toward carbon neutral energy while still relying on fossil fuels. Both the primary and secondary trapping mechanisms immobilize the injected CO2 in the reservoir and keep it securely trapped. This work focuses on one such secondary trapping mechanism, residual trapping, which is caused by capillary forces induced by natural geological heterogeneities both at the pore scale and the mesoscale (millimeter scale). To differentiate between residual trapping at the two different scales, we call the former pore-scale residual trapping and the latter capillary heterogeneity trapping. The mechanisms and the various factors affecting pore-scale residual trapping have been extensively studied previously. However, only a handful of studies have examined the role mesoscale heterogeneity plays in capillary heterogeneity trapping. This work mainly focuses on predicting, identifying, and quantifying the CO2 capillary heterogeneity trapping potential of geological formations. We first use coreflooding experiments to investigate which parameter best represents the degree of mesoscale heterogeneity in the context of residual trapping in order to predict the amount of CO2 capillary heterogeneity trapping with an empirical relationship. Then, we use statistical analysis of the data to examine the effects of mesoscale heterogeneity on capillary dominated flow behaviors and to identify and visualize CO2 capillary heterogeneity trapping behavior in sandstone core samples. Finally, we use an improved percolation model to simulate and quantify the effects of mesoscale heterogeneity on residual trapping and the extent of such effects as compared to the pore-scale trapping mechanism. The data analysis results have confirmed that post-imbibition CO2 capillary heterogeneity trapping indeed occurs upstream of capillary barriers. Furthermore, it can also occur within the capillary barriers themselves. Both experiments and simulations have shown that CO2 capillary heterogeneity trapping increases with the degree of mesoscale heterogeneity. Macroscopic percolation simulation results have shown that the capillary heterogeneity trapping contribution can be quite large for heterogeneous rocks with good mesoscale capillary barriers. Experimental results show that the variance in the drainage CO2 saturation fields created under capillary dominated flow conditions can best capture the degree of mesoscale heterogeneity in terms of predicting CO2 capillary heterogeneity trapping

Keywords: Energy Resources Engineering.
Advisor: Benson Sally 
Kovscek Anthony R. (Anthony Robert)
Tchelepi Hamdi
Quantifying geological uncertainty and optimizing technoeconomic decisions for geothermal reservoirs

Globally, 25% percent of greenhouse gas emissions result from electricity generation that is powered by burning fossil fuels. To mitigate climate change due to these emissions, we must increase the electricity portion generated by low-carbon resources, such as geothermal energy. One of the major barriers for geothermal development is financial risk due to geological uncertainty. Production from a geothermal well highly depends on the unknown location of subsurface geological structures, such as faults. Faults are the most important part of geothermal systems because they host the hydrothermal fluids. In geothermal systems, cold rain-water seeps to hot areas in the subsurface and heats up. This hydrothermal fluid then upwells through subsurface faults towards the surface. Geothermal energy developers need to find these faults to: drill wells to intersect these faults, pump out the hot pressurized water and use the water to turn turbines and generate electricity. Yet, characterizing the structure of faults carrying hydrothermal fluids is extremely difficult and uncertain. Traditionally, geoscientists assess the subsurface structure by collecting many different datasets, interpreting the datasets manually, and creating a single model of fault locations. This method, however, is often inaccurate and does not provide any information about geological uncertainty and ensuing financial risk. In this work, we show that geological uncertainty has been a major challenge for developing geothermal systems, specifically enhanced geothermal systems. Using a synthetic case study, we demonstrate that information about geological uncertainty can influence the process of making decisions regarding reservoir management. we then describe a method for generating geologically realistic structural models of geothermal reservoirs that match observed data and apply this stochastic inversion method on real data from the Patua Geothermal Field in Nevada. To conclude, we provide a case study of how geological uncertainty quantified at Patua Geothermal Field can be used to inform the choice of reservoir development actions

Keywords: Energy Resources Engineering.
Advisor: Mukerji Tapan
Horne Roland N. 
Caers Jef
Quantifying the Benefits of New Products: Music Streaming Platforms

The advent of digitization and the entry of music streaming platforms has changed the way music is consumed and discovered. In order to quantify the economic effects of music streaming, I build a structural demand model for music streaming platforms in the United States. To estimate the model, I construct a new market-level dataset with market shares and prices for 2016-2019 and augment this dataset with average consumer demographics to introduce heterogeneity in consumer tastes. I conduct several counterfactual simulations to measure the change in consumer welfare when a product or a set of products is removed from the consumer's choice set. The results from these simulations align with the story that younger populations benefit more from, and hence take to new technology more than the older age groups. I then estimate a multiproduct supply-side model to simulate a Bertrand (Nash) equilibrium and analyze the impact of a possible acquisition of SoundCloud by Spotify. The results support the idea that reduced competition in markets is detrimental to consumers.

Keywords: Streaming
Music Streaming
New Goods
Competition
Merger
Acquisition
Department of Economics
Thesis
Advisor: Yurukoglu Ali
Quantifying tumor evolutionary dynamics and predictors of response in HER2-positive breast cancer treated with targeted therapy

Evolution during treatment is a significant clinical problem that leads to treatment failure, resistance, and disease progression in many solid tumors, including breast cancer. Through analysis of clinical tissue samples and using a combination of established genomic techniques, computational modeling, and novel molecular profiling methods, this dissertation explores how HER2-positive breast tumors evolve under systemic therapy and characterizes predictors of treatment response. First using multi-region genomic sequencing and computational modeling, we show that the mutational landscape of a tumor can shift dramatically over a few months of combination chemotherapy and HER2-targeted therapy (termed "clonal replacement"). We then utilized tissue from a neoadjuvant HER2-positive breast cancer clinical trial to explore tumor-associated and immune-associated predictors of treatment response. We demonstrate the utility of spatial proteomic analysis of on-treatment biopsies to define biomarkers that stratify sensitive tumors early during neoadjuvant HER2-targeted therapy with implications for tailoring subsequent therapy. Taken together, our results shed light on the roles of heterogeneity, the frequency of resistance-causing aberrations, and the immune microenvironment in response to HER2-targeted therapy. In addition, our results also provide insights into the design of clinical trials that have a molecular analysis component

Advisor: Curtis Christina 
Altman Russ 
Petrov Dmitri Alex
Sage Julien
West Robert