VictorJuiz/thesis huggingface dataset:
Engineering Learning: Cross-Community Design, Development, and Implementation of Engineering Design Challenges at a Science Center

The perception of engineering as intimidating contributes to a lack of diversity among aspiring engineers. My research develops a deeper understanding of tinkering spaces at public science centers as an accessible pathway towards engineering. I engage in cross-community collaborations with college engineering students, industry engineers, and informal science educators to design tinkering spaces, and I analyze the effect of these spaces on the learner experience. This dissertation explores these collaborators' processes of developing engineering design challenges as well as how these processes affect the students' and engineers' understanding of learning and engineering. A variety of observations, including ethnographic case studies of the cross-community design and a comparison of the visitor experience in the space with and without the cross-community design, are synthesized into practical guidelines for creating engineering tinkering spaces./nFocusing on visitors' design processes and perceptions, I find that (1) visitors are not just playing randomly, rather many are engineering deliberately; (2) visitors initially do not necessarily identify as engineers or understand engineering, and mostly associate engineering with building; and (3) constructing designs in these activities leads to the construction of identity and agency as engineers. In particular, the physical materials and the presence of other designs in the space play a key role in visitors' problem scoping, information gathering, and concept generation. Thus, the structure of these tinkering environments empowers visitors to engineer and to continue these experiences. The cross-community collaborators contribute uniquely to the design of the challenges: the educators contribute methods for accessible learning, while the industry engineers and engineering students contribute technical authenticity. Using a human-centered design process with science center visitors, the collaborators grow to view learning as a mutual experience involving contributions from the learners. Visitors at the collaborations' challenges engage in and identify broader engineering behaviors and are better able to connect the challenges to the real world when compared to visitors at challenges without cross-community design. These results provide the basis for guidelines to improve the perception of engineering through tinkering. My dissertation contributes to knowledge on the design of and learning in these tinkering spaces, particularly how learners' engineering design processes serve as a pathway towards becoming future engineers.

Advisor: Agogino, Alice M.
Linn, Marcia C.
Kinematics and Energetics of Anna's Hummingbirds (Calypte anna) performing hovering flight in ground effect, ascending and descending vertical flight, and forward flight in an asymmetric flow

Hummingbirds are exceptional among vertebrates in their extreme flight capabilities. They are unique in their ability to not only sustain hovering flight, but also to fly backwards, dive at high speeds, and perform quick alternations in flight speed and body orientation. Such capabilities require hummingbirds to have large metabolic power reserve, mechanical power output, force production, and maneuverability. These features, along with the relative ease of working with hummingbirds in a laboratory setting, make them a particularly convenient model system to assess different aspects of flight mechanics. Hence, this thesis is broadly on the flight performance of Anna's hummingbirds (Calypte anna) (seen in the above figure), a hummingbird species found year-round on the University of California, Berkeley campus, with each chapter focusing on a different flight mode: hovering flight in ground effect (chapter 1), vertically ascending steady flight (chapter 2), vertically descending steady flight (chapter 3), and forward flight in an asymmetric flow (chapter 4). The overall goal of each chapter is to gain a greater understanding of the aforementioned flight modes (e.g. what are the kinematic correlates of each flight mode, or what are the limits that constrain such a flight mode), all of which have not been previously analyzed in any detail.

Advisor: Dudley, Robert
Safety, Risk Awareness and Exploration in Reinforcement Learning

Replicating the human ability to solve complex planning problems based on minimal prior knowledge has been extensively studied in the field of reinforcement learning. Algorithms for discrete or approximate models are supported by theoretical guarantees but the necessary assumptions are often constraining. We aim to extend these results in the direction of practical applicability to more realistic settings. Our contributions are restricted to three specific aspects of practical problems that we believe to be important when applying reinforcement learning techniques: risk awareness, safe exploration and data efficient exploration./nRisk awareness is important in planning situations where restarts are not available and performance depends on one-off returns rather than average returns. The expected return is no longer an appropriate objective because the law of large numbers does not apply. In Chapter 2 we propose a new optimization objective for risk-aware planning and show that it has desirable theoretical properties, relating it to previously proposed risk-aware objectives: minmax, exponential utility, percentile and mean minus variance. In environments with uncertain dynamics, exploration is often necessary to improve performance. Existing reinforcement learning algorithms provide theoretical exploration guarantees, but they tend/nto rely on the assumption that any state is eventually reachable from any other state by following a suitable policy. For most physical systems this assumption is impractical as the systems would break before any reasonable exploration has taken place. In Chapter 3 we/naddress the need for a safe exploration method. In Chapter 4 we address the specific challenges presented by extending model-based reinforcement learning methods from discrete to continuous dynamical systems. System representations based on explicitly enumerated states are not longer applicable. To address this challenge we use a Dirichlet process mixture of linear models to represent dynamics. The proposed model strikes a good balance between compact representation and flexibility. To address the challenge of efficient exploration-exploitation trade-off we apply the principle of Optimism in the Face of Uncertainty that underlies numerous other provably efficient algorithms in simpler settings. Our algorithm reduces the exploration problem to a sequence of classical optimal control problems. Synthetic experiments illustrate the effectiveness of our methods.

Advisor: Abbeel, Pieter
Jordan, Michael I
Combinatorial patterns in syzygies

Affine semigroup rings are the coordinate rings of not necessarily normal toric varieties. They include the coordinate rings of the Segre-Veronese embeddings of projective spaces, and special projections of those. The study of affine semigroup rings lies in the intersection of commutative algebra, algebraic geometry and combinatorics. In this thesis, we study the syzygies for certain classes of affine semigroup rings./nThe Betti numbers of affine semigroup rings can be computed as the dimensions of homology groups of certain simplicial complexes. Therefore, the study of the Betti numbers of affine semigroup rings can be translated into some combinatorial problems. The idea of using combinatorial topology to study syzygies originated from the work of Hochster, Reisner and Stanley in the seventies and eighties and since then have been an active area of research and proved to be useful in lots of cases./nIn the first chapter, we introduce the problems concerned in our dissertation, and their relations to topology of simplicial complexes and representation theory of symmetric groups. We also include some background material from combinatorial commutative algebra, algebraic geometry, and representation theory./nIn the second chapter, we use combinatorial and representation theoretic methods arising from work of Karaguerian, Reiner and Wachs to reduce the study of the syzygies of Veronese varieties to the study of homology groups of matching complexes. In turn we use combinatorial methods to show the vanishings of certain homology groups of these matching complexes, giving a lower bound on the length of the linear part of the resolution of the Veronese varieties. In the case of third Veronese embeddings, we carry out the computation to prove the Ottaviani-Paoletti conjecture./nIn the final chapter, we study a conjecture of Herzog and Srinivasan and a higher analog. The conjecture says that the Betti numbers of affine monomial curves under translations are eventually periodic. We prove the conjecture, and use it to study the analogous question for higher dimensional affine semigroup rings under translations and some other consequences.

Advisor: Eisenbud, David
Creative Destruction: Memory, Public Finance, and the State in New York City

This dissertation demonstrates how the neoliberal state marshals public finance and public memory to incorporate itself into the contemporary urban landscape. It investigates sites in the built environment where the state deploys public funds to subsidize private construction projects that are fiscally unsound, using the institutional form of the public authority to covertly mediate between itself and the private sector. Combining discursive analysis of news media, funding allocation records, and the sites themselves, it looks at the World Trade Center reconstruction, a bus depot in Harlem, and Freshkills Park in Staten Island, a former landfill, and examines the effects of these projects both on urban space and public memory itself. The dissertation argues that the state uses public funds to inaugurate sites of memory in the city's cultural and political landscape in order to assert its ethical and political legitimacy in a moment when that legitimacy is bound up in its relationship to private capital. This is an unexpected manifestation of what Marx and Schumpeter describe as "creative destruction" - the destruction of capital necessary to the continuation of capitalism - but what the dissertation shows is that this process not only sustains capitalist economy, but also removes democratic participation from planning the built environment while regenerating the state's failing legitimacy in times of fiscal crisis. The dissertation employs historical and archival research on public authorities, including the Port Authority of New York and New Jersey, and qualitative research, such as personal interviews with project planners, neighborhood residents, tourists, state officials, and activists. By showing that state projects of memorialization are central to mediating between private interests and the capitalist state, it contributes to scholarship in state theory, urban planning, and material culture.

Advisor: Esmeir, Samera
Watts, Michael J
The Topography of Wellness: Mechanisms, metrics, and models of health in the urban landscape

Within the past 10 years there has been a rapid growth in studies addressing the link between the built environment's relationship to physical activity and chronic disease. However, even in a time of rapidly expanding spatial data, researchers still struggle with how best to measure the built environment within this context. In the past, disease mapping and an etiologic approach to public health often led to the elimination of entire neighborhoods (and the relocation of vulnerable populations within). Today, the origins of these "man-made" illnesses are often a confluence of genetic, biologic, and small-scale environmental factors, exacerbated by today's urban landscape--an environment that is in no way accidental. Through the lens of current research on walkable neighborhoods and an eye towards health equity, this dissertation examines larger questions regarding both the historical and present relationship between urban landscape and health. To begin to address these complex interactions not only between individuals and neighborhoods, but between parts of the built environment itself, this research also proposes an alternative model for built environment measurement that maps multiple opportunities and barriers to well-being in the urban landscape./nStudies still often rely on coarse measures such as density and land use to judge the walkability of a neighborhood, and often neglect more nuanced features of the built environment. The promised effectiveness of "walkable neighborhoods" also still relies on certain foundational concepts that proved to be pitfalls in past movements focused on health and the built environment. Proponents of walkable environments advocate for a one-size-fits-all framework of the influence of the built environment. This overlooks the fact that vulnerable populations, such as the elderly and youth, tend to feel the effects of the environment more acutely, or that low-income populations don't have the same amount of leisure time available for physical activity. Another is the premise that all can choose to live in a neighborhood deemed healthy, a confounder often referred to as "self-selection" in the literature--a premise that is disconnected from today's economic landscape. It is also unclear how the plethora of research on built environment and physical activity will become realized while avoiding the mistakes of past movements centered surrounding health./nThis dissertation traces the historical and theoretical foundations of health and the built environment to the current state, as well as possible implications of contemporary study. Using lessons learned from a case study of how active design research has become policy in Sacramento, California, I propose a flexible model of built environment measurement for chronic disease outcomes. These multiple mappings of the city can reveal where risk of illness and opportunities for well-being lie in the built environment for focused and thoughtful interventions.

Advisor: Mozingo, Louise
Integrated Modeling and Design of Photoelectrochemical Water-Splitting Cells

The photoelectrochemical production of fuels is an interesting research topic that aims to provide a low-cost method for storing solar energy. A one-dimensional model of a photoelectrochemical cell for solar water splitting has been developed, with applicability to both wired and wireless designs. The model of the light absorber handles electron and hole transport. The model of the electrolyte accounts for mass transport through regions of aqueous solution, including stagnant diffusion layers and bulk regions to address mixing due to bubbles, natural convection, or other sources. A polymer membrane may be present in the electrolyte./nThe models of the light absorber and the electrolyte are integrated through the reactions taking place at the interface between them. Charge transfer from the semiconductor to the solution is handled using a kinetic model involving reactions between the species in both the light absorber and the electrolyte. A simplified model is also presented for use when concentration gradients in the electrolyte are negligible. The simplified model captures the effect of the electrolyte in the boundary conditions for the light-absorber./nThroughout, the model is validated against experimental data. At the outset, simulated output compares favorably with current-potential data for a hydrogen-evolving light absorber with varying degrees of simulated solar illumination. Later, the program is able to match current-potential data and bulk pH values for a membrane electrolysis cell with several electrolytes./nThe model is first used to study the effect of changing the electrolyte on the performance of a photoelectrochemical cell. It is discovered that using supported dilute acids or buffered electrolytes in an attempt to work in near-neutral conditions is ineffective. Cells with neutral electrolytes cannot run at high current density due to transport limitations in the electrolyte and solubility limitations that are encountered due to electrodialysis./nLater, an absorber-in-membrane design for a photoelectrochemical cell is considered. Gas crossover is identified as a significant issue in these systems, and metrics are developed for evaluating system performance properly. Material targets are established. For instance, membranes with ten times the gas-blocking properties of currently available polymers (i.e., Nafion) are desired.

Advisor: Newman, John
The C-shunt Flux Qubit: A New Generation of Superconducting Flux Qubit

While quantum computation has the potential to revolutionize the scientific community, to date no architecture has been developed which offers the necessary combination of high coherence times and massive scalability. Superconducting flux qubits satisfy the second requirement well but to date useful devices are limited to coherence times of typically only a few &mus. In this dissertation we examine the possibilities of improving the coherence performance of the flux qubit to the levels required for fault-tolerant quantum computation. We find that coherence times for many devices are limited by photon-induced quasiparticles and mitigation of these quasiparticles increases coherence times by more than a factor of two. Beyond this, however, we find little improvement in flux qubit performance compared to prior results. Despite improved fabrication techniques and varied device designs we find flux qubit coherence times are still typically below 5 &mus. Furthermore, wide device-to-device variations are observed which prevent effective scaling of the flux qubit to quantum information circuits./nBased on the proposal by You, et al. we develop of a capacitively-shunted version of the flux qubit called the C-shunt flux qubit. With the addition of a capacitive shunt across the small junction of the flux qubit we are able to reduce the amplitude sensitivity to both charge and flux noise by more than a factor of three. The result is a predicted ten-fold enhancement in the coherence times compared to the unshunted flux qubit. At the same time we preserve much of the anharmonicity of the flux qubit resulting in a device with coherence times comparable to modern transmons but with a factor of four better anharmonicity and more flexible coupling configurations./nBy using a high-quality MBE aluminum shunt process on an annealed sapphire substrate coupled with a more conventional electron-beam-evaporated aluminum Josephson junction process we fabricate hybrid C-shunt flux qubits. We also incorporate a new bridgeless junction technique which offers more robust and repeatable fabrication processing. This technique enables improved accuracy of the junction sizing, a trait which will become essential as we move to multi-qubit experiments. T1 and T2 times for these C-shunt devices reach in excess of 40 &mus at degeneracy, achieving the predicted ten-fold improvement based on the reduced noise sensitivity. At the same time we see decreased device-to-device variation with typical T1 times exceeding 20&ndash25 &mus at all bias points. Combined with the high anharmonicity and standard planar fabrication techniques these coherence times make the C-shunt flux qubit a competitive candidate for fault-tolerant quantum computation.

Advisor: Clarke, John
The Aesthetics and Establishment of Analog Post-Production

This dissertation examines the emergence and establishment of analog post-production during the transition to sound. I analyze how the analog post-production system cannibalized the nascent post-production process of silent film, whereby the image from the filmmakers was combined with non-standardized sound produced live in the theater. Multiple forces at the theaters asserted influence over a film's presentation. Exhibitors, for example, created a de facto form of post-production by altering films to suit scheduling strategies, local tastes, and aesthetics, and screenings varied widely./nFollowing the ascendance of analog post-production in the American studio system, a shift began to take place with the introduction of sync sound, as a standardized film could potentially be created from heterogeneous visual and audio elements, recorded at different times and in different spaces. This process favored the invisible -- the denial of labor conducted by specialized workers -- via the seamless continuity editing of sound and image. Film scholars have long made the point that post-production, specifically continuity editing, conceals labor and technology. Indeed, this is the premise on which film theory of the 1970s is based. Most scholars approached this issue by analyzing the finished product, the film "text." I intervene to study the actual work of, and discourses produced around, post-production itself. I argue that the introduction and codification of analog post-production had a profound impact on filmmaking as well as on exhibition./nWith the emergence of synchronous sound in the late 1920s, post-production asserted itself into what I refer to as the analog era with its own distinct mode of creation defined by a potentially endless process that could result in myriad forms of a film. In this scheme, practitioners obtain and manipulate various sound and visual elements and then synchronize, or marry them. Under this system, a new set of practitioners finalizes film form, where the workers of post-production replace those of the theater. These analog post-production workers tend to view a film as a collection of elements controlled and shaped in the post-production process. For filmmakers, a movie's creation becomes tied more to this process and less to the moment of production on the set that has for so long been a focus of film studies.

Advisor: Whissel, Kristen
Kaes, Anton