VictorJuiz/thesis huggingface dataset:
Lithium Plating Detection, Quantification, and Modeling to Enable Lithium-Ion Battery Fast-Charging

A key challenge for energy storage and conversion technologies is finding simple, reliable methods that can identify device failure and prolong lifetime. Lithium plating is a well-known degradation process that prevents Li-ion battery fast charging, which is essential to reduce electric vehicle ‘range anxiety’ and enable emerging technologies such as aerial drones and high-performance portable electronics. The ability to detect the initial onset of lithium plating from easily accessible voltage measurements would greatly improve battery safety and feedback controls modeling. In this work, we first highlight the application of a differential open-circuit voltage analysis (dOCV) to detect when Li plating begins during a single charge for room temperature fast charging. We also show that dOCV can identify the Li plating onset during cycling with sensitivity of 1 mg plated Li per gram graphite, equivalent to 1% of the graphite capacity, indicating that this method has commercial promise for on-line Li detection./nNext, we demonstrate the power of simple, accessible, and high-throughput cycling techniques to quantify irreversible Li plating spanning data from over 200 cells. We first observe the effects of energy density, charge rate, temperature, and State-of-Charge (SOC) on lithium plating, use the results to refine mature physics-based electrochemical models, and provide an interpretable empirical equation for predicting the plating onset SOC. We then explore the reversibility of lithium plating and its connection to electrolyte design for preventing irreversible Li accumulation. Finally, we design a method to quantify in-situ Li plating for commercially relevant Graphite|LiNi0.5Mn0.3Co0.2O2 (NMC) cells and compare with results from the experimentally convenient Li|Graphite configuration. The hypotheses and abundant data in this section were generated primarily with equipment universal to the battery researcher, encouraging further development of innovative testing methods and data processing that enable rapid battery engineering./nFinally, we consider the challenge of highly variable charging conditions possible in commercial cells. We combine pseudo-2D electrochemical modeling with data visualization methods to reveal important relationships between the measurable cell voltage and difficult-to-predict Li plating onset criteria. An extensively validated model is used to compute lithium plating for thousands of multistep charging conditions spanning diverse rates, temperatures, states-of-charge (SOC), and cell aging. We observe an empirical cell operating voltage limit below which plating does not occur across all conditions, and this limit varies with battery state-of-charge and aging. A model sensitivity analysis also indicates that when comparing two charging voltage profiles, the capacity difference at 4.0V correlates well with the difference in the plating onset capacity. These results encourage simple strategies for Li plating prevention that are complementary to existing battery controls.

Advisor: McCloskey, Bryan D
Toward Trustworthy Scientific Inquiry and Design with Machine Learning

The last decade has witnessed rapid development and deployment of machine-learning systems across science. Such systems can supply predictions about scientific phenomena far more quickly and cheaply than gold-standard experiments, and are being used in efforts to both discover scientific knowledge and design new biomolecules. However, an important question remains unanswered: since machine-learning systems make errors, how can we use them in a trustworthy way for scientific discovery and design? This dissertation takes steps toward helping to ensure that the biomolecules we design and the scientific conclusions we draw using machine learning can be trusted./nWe begin in the setting of machine learning-based design. The goal in this setting is to propose novel objects such as proteins, small molecules, or materials with desired properties, in a way that is guided by machine-learning models of such properties. Toward addressing model trustworthiness for design, we propose (i) a method for learning models that accounts for the distribution shifts inherent to design, and (ii) a method for constructing statistically valid confidence sets for the properties of objects designed using machine learning./nFinally, we examine the trustworthy use of machine learning for drawing scientific conclusions. In particular, we consider the increasingly relevant setting of treating predictions made by machine-learning systems as “data” in estimating quantities of scientific interest. We propose prediction-powered inference, a novel statistical framework for constructing valid confidence sets in this setting, which enables researchers to incorporate evidence from machine-learning systems into their scientific inquiry in a standardized and principled way.

Advisor: Jordan, Michael I
Listgarten, Jennifer
Reinventing the Wheel of Time: An Art History of the Kālacakra Tantra

This dissertation is an art historical analysis of a set of objects related to a ritual corpus of Tibetan Buddhism known as the Kālacakra tantra. Objects are tracked according to distinct socio-cultural conditions, each of which developed into differing interests regarding the Kālacakra tantra, interests distinct from the purposive and functional norms of Tantric Buddhism itself. The dissertation thus attempts a somewhat different methodology from other historical narratives regarding Buddhist art by moving beyond iconographic interpretation to analysis of how a common iconographical matrix is serially adapted into divergent forms and functions across distinct social formations in time and space. Field research and embodied analysis are prioritized./nIndividual chapters attempt to isolate individuals and social formations for focused analysis. The introduction covers some background by focusing on the earlier, established dissemination of the Kālacakra tantra during and immediately after Yuan dynasty patronage of the tantra following the thirteenth century. This patronage was borne out by art from the Sa-skya sect of Tibetan Buddhism, in which Kālacakra imagery was subsumed into standardized ritual practices. This chapter also introduces common themes linking the subsequent parts of the dissertation, such as the sacrality and iconic presence common to works of Buddhist art. The second chapter focuses on how the seventeenth century Ganden Phodrang of the Geluk sect in central Tibet attempted to standardize Kālacakra imagery. A guidebook produced by the regime was an assertion of secular control bound to the the position of regent. The third chapter discusses the invention of a Kālacakra Hall for the Qing imperial capital in Beijing, and how the this hall reflected the multi-ethnic and identity-based values that the Qing court used to assert its power through the hall. The fourth chapter discusses the eighteenth century development of Labrang Monastery and its Kālacakra Hall. The large, relatively autonomous Tibetan Buddhist monastery in Amdo, in a region in halfway between central Tibet and the Qing capital Beijing, defined its hall in terms of its local population. A brief conclusion reconsiders the totality of works.

Advisor: Berger, Patricia
Studies of Frustration and Disorder via Electrical Manipulations

This dissertation primarily explores the nature and consequences of frustration and disorder in the intercalated transition metal dichalcogenide FexNbS2. This exploration is done mainly through the unconventional measurement of resistivity changes in response to brief electrical stimuli. These measurements uncover surprising details of the system, which are otherwise very difficult to observe, and they are an end in and of themselves, establishing a promising path towards low-energy antiferromagnetic spintronics. This work also includes measurements in high magnetic fields which elucidate the phase diagram and microscopic interactions in this system, more conventional measurements which supplement our understanding, and studies of close relatives of FexNbS2 with an eye towards their potential applications and the insights they can allow into their sister compounds.

Advisor: Analytis, James G
Liberating the Siloed Gateway: Application-Agnostic Connectivity and Interaction for the Internet of Things

At its inception, the Internet of Things (IoT) was predicted to connect trillions of inexpensive smart devices to the Internet in mere decades, embedding paradigm-shifting utility, communication, and convenience into everyday things. Since then, a number of connected speakers, thermostats, doorbells, lights, and wearables have entered the market and our homes, but devices and sensors further constrained by processing power, memory, energy, and networking capabilities struggle to find their way to market. This is due, in part, to the prevailing model in industry of requiring a different application-layer gateway — often in the form of a device-specific router box or smartphone app — to link each unique IoT device to the Internet and allow users to interact with it. Unfortunately, this siloed approach cannot sustain the true scale, density, and capability of the IoT vision./nTo break free from such siloed gateway standards which restrict scalability, affordability, and accessibility for constrained IoT devices, we propose a set of application-agnostic approaches to connectivity and interaction. For connectivity, we design a general-purpose network architecture consisting of ubiquitous short-range gateways that openly facilitate data transport for constrained devices to the Internet. By simplifying the gateway to its most essential parts, communications and processing, we can implement the architecture on inexpensive off-the-shelf system-on-chips and on existing smartphone infrastructure. These static and mobile approaches provide coverage for both reliable data throughput scenarios and ephemeral connectivity needs. For interaction, we design a browsing architecture that provides a seamless, scalable approach to discovering and interacting with nearby Things. The system takes advantage of multiple network patterns and modern web technologies to automatically detect devices and supply users with rich device interfaces that can enable interaction directly over local networking protocols. We implement and deploy a mobile-based browsing platform to facilitate this and provide tools for device developers. We further explore techniques for more physically-tied interaction, including extension to mixed reality./nThe proposed approach to IoT connectivity and interaction opens up exciting possibilities for the future of the Internet of Things. By breaking down the barriers imposed by siloed gateway standards and introducing a set of approaches that form a general-purpose alternative, this work paves the way for the creation of more innovative and versatile IoT devices and interfaces. The design principles presented provide a simple, yet dynamic framework for enabling Internet connectivity for IoT devices, and for users to interact with them in a more intuitive and seamless way. These architectures represent significant steps forward in realizing the full potential of the Internet of Things, making it more accessible to everyone, and further advancing the development of the smart and connected world of the future.

Advisor: Dutta, Prabal
Application-Driven Development of Computational Tools and Algorithms for Machine Learning and Mean-Field Games

In today's rapidly evolving technological landscape, the development and advancement of computational tools and algorithms have become paramount across a wide range of research fields. This holds particularly true in various domains of computational mathematics, encompassing areas such as machine learning, optimization, and algorithmic game theory. The computational tools serve as essential enablers, empowering researchers and practitioners by facilitating efficient modeling, analysis, and prediction. Algorithms are essential components of computational tools, which provide instructions for data processing, pattern recognition, and decision-making./nThis dissertation focuses on developing computational tools and algorithms for specific applications in the interconnected fields of optimization, machine learning (ML), and mean-field games (MFGs). First, to address the absence of a comprehensive computational tool for MFGs, we present MFGLib, an open-source Python library designed to provide a user-friendly and customizable interface for solving Nash equilibria in generic MFGs. Second, we demonstrate that the search for Nash equilibria in MFGs and various ML problems can be formulated as non-convex optimization problems, where the presence of saddle points significantly impedes the effectiveness of gradient descent algorithm and its variants. To help optimization algorithms escape saddle points efficiently, we introduce a novel perturbation mechanism based on the dynamics of vertex-repelling random walk. This leads to the development of two new algorithms, perturbed gradient descent adapted to occupation time (PGDOT) and its accelerated version (PAGDOT). Theoretical guarantees for these algorithms are established, and through extensive numerical experiments, we showcase their superiority over several state-of-the-art optimization methods. Last, we explore a relatively independent machine learning task---detecting overutilization and fraud in healthcare. We focus on developing an ensemble model based on Stacked Generalization (stacking) to detect overutilization in Medicare within the field of Ophthalmology. Our results highlight the superiority of the stacking ensemble model over traditional ML models in accurately distinguishing overutilizing ophthalmologists from non-fraudulent ones.

Advisor: Guo, Xin
Felt History: Literary Senses of the Historical in People’s Poland and the German Democratic Republic around 1989

Articulating an original reading strategy that builds on both American feminist affect theory and anthropological models of historical consciousness, this dissertation advances a new theoretical account of the role played by the sensory or bodily awareness of history in Polish and East German literature. Its argument consists of, on the one hand, an account historical experience in the state-socialist period in People’s Poland and in the German Democratic Republic that focuses on specific, qualitative experiences of historical time and that places them in their cultural contexts and historical genealogies. These qualitative temporalities appear as concrete amalgamations of emotion and time. The three such amalgamations on which this dissertation focuses are: Stalinist cheerfulness and its “elastic” sense of history; the empty lateness of pre-Solidarność Poland in the 1970s, and the atmospheric depression hanging over Berlin directly before the Mauerfall. On the other hand, this argument presents a theoretical account of historical consciousness as such, which uses the example of socialist historical consciousness to argue that the categories of feeling, affect, and emotion are, in fact, central to how history is experienced throughout Modernity. This is, again, a wholly original argument that builds on literary, historical, anthropological, and cultural-studies theory to advance a new understanding of historical time, outside of chronology, simultaneity, and forms of linear ordering. These readings of the Polish and East German literature are, at once, an attempt to deprovincialize the socialist novel by elucidating its universal claims about the relationship of historical knowledge to historical experience.

Advisor: Largier, Niklaus
Formal Specification and Verification of Secure Information Flow for Hardware Platforms

Hardware platforms, such as microprocessors and Trusted Execution Environments (TEEs), aim to provide strong memory isolation properties. However, in recent years, this has been shown not to be the case through hardware attacks such as the class of transient execution attacks. These attacks affect programs executing on widely-used microprocessor designs in our present-day devices. Although mitigations have been proposed, many have not been adopted and lack formal guarantees. As a result, security-critical applications have been conservative in using hardware platforms without some form of cryptographic approach for secure computation, despite the additional computational overhead. One approach to ensure safety for this class of attacks is to use formal methods to prove information flow properties. Yet, there is limited work in verifying attacks on hardware platforms that are heterogeneous in nature, namely those that contain hardware and software in the trusted computing base./nThis thesis defines a notion of secure information flow for hardware platforms and proposes methods to formally verify non-interference-based properties efficiently using abstractions and composition. To accomplish the former, we formalize the trace property-dependent observational determinism property for capturing a new class of non-interference properties. This property is motivated by verifying transient execution attacks and the need for secure speculation. To enable efficient verification on hardware platforms, we introduce an efficient proof system, SymboTaint, and the formalism of information flow state machines to reason about secure information flow compositionally. Finally, we explore a complementary method to enforce secure information flow for general programs by relaxing the programming model of a family of TEE designs and by formally verifying them. This direction builds on top of existing abstractions of TEEs to provide memory isolation guarantees with an efficient memory-sharing scheme on TEEs through combined design and verification. Together, this provides a methodology for enforcing memory isolation for heterogeneous systems, where joint modeling and analysis of hardware and software have become imperative for security.

Advisor: Seshia, Sanjit A
Some geometric methods in chromatic homotopy theory

This thesis is a conglomerate of several results in algebraic topology united by the common thread of taking seriously the idea that geometric considerations can be useful for proving algebraic results in the field of chromatic homotopy theory. These results include a geometric construction of equivariant elliptic cohomology at the Tate curve, abstract derivations of the dual Steenrod algebras at all primes, and geometric presentations of higher algebraic structures.

Advisor: Teleman, Constantin
Understanding the Galactic Black Hole Population with Gravitational Microlensing

This thesis addresses the problem of finding and characterizing isolated Galactic stellar-mass BHs via the technique of gravitational microlensing. We present work on both the theoretical and simulation front as well as an observational and modeling perspective./nPrior to 2019, most estimates for the number of BHs in the Milky Way were highly uncertain and dated. This limited our ability to accurately predict and interpret the number of BHs detectable with microlensing. To address this shortcoming, we develop a Milky Way microlensing simulation called PopSyCLE (Population Synthesis for Compact object Lensing Events). Using PopSyCLE, we identify an improved strategy for finding and identifying BHs photometrically, advancing our ability to identify good BH candidates and enable statistical constraints on the BH population to be made./nAlthough photometric microlensing can statistically characterize BHs, it cannot disentangle the lensing system’s relative proper motion from the lens’s mass. Astrometric microlensing is required to break this fundamental photometric degeneracy to definitively measure a lens’s mass and confirm its BH nature. We analyze 5 archival BH candidate microlensing events by jointly modeling ground-based microlensing survey photometry and Hubble Space Telescope (HST) astrometric observations. We identify one candidate, OB110462, to be a neutron star or low-mass BH (1.6 - 4.4 solar masses), making it the first dark isolated compact object confirmed with a mass measurement. In addition, using the full sample of five objects including non-BH detections and quantifying selection effects, we find this sample to be consistent with 100 million isolated BHs in the Milky Way./nThe exact nature of OB110462 was disputed; another group independently found its mass to be 7 solar masses, firmly establishing it as a higher-mass BH. We re-analyze OB110462 using new and re-reduced data, along with updated analysis software. We find that OB110462 is a 6 solar mass BH, making it a solid BH detection. The main reason for finding a higher mass in this work is that the software used in previous work underestimated a positional bias correction, resulting in different astrometric measurements and hence a different mass./nPresently, microlensing is a small and relatively obscure subfield of astronomy. However, this will change with the launch of NASA's next flagship mission, the Nancy Grace Roman Space Telescope. Roman will conduct a microlensing survey of the Galactic Bulge. In addition, other public time-domain surveys will enable searches for microlensing events. In order to enable broader participation and newcomers to the field, we provide some examples of important considerations to take into account when modeling microlensing light curves. We also document, explain, and provide examples of some microlensing notations and conventions not easily found in the literature.

Advisor: Lu, Jessica R.
Understanding the Development of East Oakland Youth at the Nexus of Place, Race, and Wellbeing

This dissertation explores the relationship between place and youth development, focusing on the challenges faced by youth of color living in low-income urban areas. It highlights the uneven distribution and limited access to essential resources and opportunities such as housing, healthcare, education, and employment, which contribute to developmental and health inequities among marginalized youth. I respond to three key challenges in the place-based literature: the poor conceptualization of place, lack of youth voice, and the need to problematize definitions of wellbeing in partnership with those most intimately impacted by social issues. In doing so I apply mixed methods through interviews, focus groups, and participatory GIS with East Oakland youth of color. In paper 1, I define East Oakland based on the definitions of youth who live there. I develop a holistic understanding of the location, locale, and sense of place that defines this geographic subset of the City of Oakland. In paper 2, I compare how youth of color experience school and youth-serving organizations in ways that bolster and hinder their subjective psychological wellbeing. In paper 3, I problematize the EPOCH conceptualization of wellbeing through focus groups with East Oakland youth. I find that assessing youth development based on psychological wellbeing is not sufficient to capture the challenges experienced by marginalized youth. This dissertation highlights the significance of adopting person-centered approaches to research. It challenges the perception of urban youth of color as passive actors and underscores their expertise, strength, and skills. By recognizing and empowering marginalized youth, societal stereotypes and oppressive practices can be challenged, enabling youth to play active roles as both recipients and providers of services and support in their own development.

Advisor: Chow, Julian