VictorJuiz/thesis huggingface dataset:
Sensing and Harvesting Pressure Fluctuations in Harsh Environments

Pressure is one of the most frequent and important parameters utilized in many applications to provide critical information about the operation of a system as well as a potential mechanical energy source. Among various pressure-related devices, very few function in harsh environment which includes high temperature, high pressure, highly corrosive, or biofouling conditions. In the first part of this dissertation, a high temperature pressure sensor with a novel concentric ring-circle-shape design is proposed specifically for the geothermal applications with detailed modeling, fabrication, and characterization results. A concentrically matched ring-circular capacitance pressure sensor design is proposed to tackle the common mode noise problem of km-long cables in geothermal wells. Furthermore, to provide a high temperature and corrosive environment survivability, silicon carbide is utilized as it has superior material properties as compared to silicon in harsh environments. Experimentally, it was shown that the novel design can provide differential capacitance output at temperatures of 180℃ and capacitances ranging between 0.14 pF to 1.45 pF were observed from a sensor designed to operate under 1 MPa. In the second part of this dissertation, an energy harvester application is proposed to make the use of pressure fluctuations within the lateral ventricles of the brain which is a biofouling environment. This time, a concentric ring-circular design is utilized to convert the mechanical pressure fluctuations to electrical energy efficiently. The harvesters were fabricated using aluminum nitride as the piezoelectric material and the increase in efficiency of the proposed design was shown as characterized by both in-air and underwater tests. A 3D-printed lateral ventricle mockup setup was used to mimic the operation of the harvester in lateral ventricles and the harvester with a diameter of 2.5 mm generated a power of 0.62 nW. Moreover, considering the potential issues in deployment and mounting, a flexible harvester was developed using PVDF and PET materials and under water characterization the harvester with 3 mm diameter resulted in power of 1.75 nW.

Advisor: Lin, Liwei
Pisano, Albert P
Constructing Resilience: Real Estate Investment, Sovereign Debt and Lebanon’s Transnational Political Economy

In urban studies scholarship, Lebanon is often theorized on the frontiers of sectarian conflict as well as on the frontlines of neoliberalism. Entangling real estate investment, sovereign debt and transnational financial circulations from Arab Gulf investors and the Lebanese diaspora, managed by the Banque du Liban and scrutinized by the United States Treasury, the Lebanese political economy was – and still is – swayed by the fortunes of war. According to literature on the political economy of violence, profits are often made in times of war, a context appropriate to the civil war and postwar eras, during which spoils of war enriched the pockets of warlords-turned-politicians. Yet as the effects of the Syrian conflict spill across the border, encumbering Lebanon’s long paralyzed politics, straining its already deteriorated infrastructure and intensifying uncertainty with punctuated bombings, certain sectors prosper not because of violence but in spite of it. The skyline of Beirut is covered in construction cranes erecting affluent, if empty, apartments; the banks are infused with deposits invested in the debt of a sovereign bankrupt in ways not simply financial. Both real estate and banking are said to be resilient, a discourse so often repeated that resilience has become the dominant mode by which Lebanon is broadly understood, and not only by the developers and bankers with a financial interest in this depiction. Resilience has taken on the status of a self-evident truth. Tracing transnational investment into these two sectors, the pillars of the economy, this dissertation excavates the history around which resilience arose as a concept and thereafter endured. Rather than a description or explanation, resilience is instead – this dissertation argues – a dispositif organizing an entire political economy around the attraction of foreign financial inflows and ongoing emigration, ensuring the resilience for which Lebanon is renowned also perpetuates much of its underlying instability.

Advisor: Caldeira, Teresa
Beyond Photo-Consistency: Shape, Reflectance, and Material Estimation Using Light-Field Cameras

Light-field cameras have recently become easily accessible in the consumer market, making applications such as post-shot refocusing and viewpoint parallax possible. An important benefit of light-field cameras for computer vision is that multiple viewpoints or subapertures are available in a single light-field image, enabling passive depth estimation. However, most existing approaches are based on photo-consistency, i.e., all viewpoints exhibit the same color when focused to the correct depth. This assumption does not hold in a number of circumstances, e.g., in the presence of occlusions, and when the surface is not Lambertian./nIn this thesis, we refrain from assuming photo-consistency, and explicitly deal with the situations where it fails to hold. First, we propose a novel framework that can handle occlusions when estimating depth, so we are able to get sharper occlusion boundaries in the obtained depth maps. Next, we extend traditional optical flow to the case of glossy surfaces, and derive a spatially-varying (SV) BRDF invariant equation. Using this equation, we can then recover both shape and reflectance simultaneously using light-field cameras. Finally, we show an application of recognizing materials in light-field images, based on the reflectance information extracted using learning-based methods. By looking beyond photo-consistency, we are able to estimate better depths and recover reflectance and material types, which can be useful for a variety of vision and graphics applications.

Advisor: Ramamoorthi, Ravi
Efros, Alexei A
Negotiating the Sharing Economy: Challenges and Opportunities for Democracy in the Era of Neoliberal Capitalism

Since its emergence in 2008, the “sharing economy,” which includes such platform companies as Uber, Airbnb, and TaskRabbit among many others, has transformed entire industries and changed the lives of millions of workers, commuters, and tourists worldwide. It has also introduced new opportunities for and challenges to democracy. Foremost among the opportunities is the sharing economy’s potential to increase personal encounters between strangers in the semi-private, semi-commercial spaces it creates. Such encounters offer the possibility of enhanced mutual trust and understanding among citizens, each of which is critical to successful self-government in a pluralistic society./nYet the commercial sharing economy also threatens democracy, in three main ways: first, by requiring participants to rate and review, and thus engage in mutual surveillance of, each other; second, by creating new avenues for often hidden discrimination against others, circumventing existing anti-discrimination law, and third, by perpetuating a notion of the individual as a competitive, maximizing, economic being, even as the companies often couch their services in the language of sharing. This dissertation investigates these opportunities for and challenges to democracy, and considers the way in which the pressures and incentives of financial capitalism have caused the sharing economy to develop, over its first decade, in a manner that has exacerbated the challenges while diminishing the opportunities.

Advisor: Brown, Wendy
Design of Passive Artificial Knee For Individuals with Paralysis

The objective of this research is to design an artificial knee (either a prosthetic knee or an orthotic knee) to exhibit the basic behavior of the human knee. Such artificial knee should exhibit three behaviors:/n1. Resist the knee flexion during the stance phase to help support a portion of user’s weight./n2. Encourage knee flexion during the swing flexion phase to assist in toe clearance./n3. Allow free swing extension in the swing extension phase./nAn important aspect of this invention is that all of the above specifications are achieved passively without the use of any actuators, computers and sensors. This knee device has designed, fabricated, and tested to enable paraplegics to walk in an exoskeleton. This invention is a planar machinery that achieves the above specifications in a simple architecture. Such knee has shown to be a good fit for certain paraplegics who prefer more rehabilitating work out because it allows more freedom and provides adjustable support. This artificial knee is highly adaptable for its modularity, and the simple yet highly functional design has the potential to significantly decrease the manufacturing cost.

Advisor: Kazerooni, Homayoon
The Racial Life of Things

The Racial Life of Things is a cultural biography of the racialization of the sneaker. This project identifies the emergence of Michael Jordan, his 1984 partnership with Nike, and the eventual ban of his first signature shoe by the National Basketball Association as inaugurating a critical shift in the polysemous nature and cultural position of sneakers within the United States (and globally). Drawing upon the work of performance studies and thing theory, this work offers the concept of “the racial life of things” to examine how and why sneakers, arguably, more than any other consumer object, have become deeply and inextricably linked to blackness and masculinity. Moreover, this project contends that sneakers work both, in tandem with, and in the absence of, corporeal bodies, to do the work of making gender and race “real.”  Using discourse analysis, semiotics, fashion and performance theory, The Racial Life of Things traverses a diverse set of cultural artifacts––corporate endorsements and advertisements, popular news media images and discourse, and consumer narratives–– and proffers that everyday cultural objects like sneakers can work to reveal the opacities and slippages between subjecthood and objecthood and offer productive modes for understanding race and gender, specifically black masculinities, more broadly.

Advisor: Catanese, Brandi
The Development of Palladium-Catalyzed C-H Oxidation Reactions and Cooperative Chemoenzymatic Reactions

Abstract/nThe Development of Palladium-Catalyzed C-H Oxidation Reactions and Cooperative/nChemoenzymatic Reactions/nBy/nZachary Charles Litman/nDoctor of Philosophy in Chemistry/nUniversity of California, Berkeley/nProfessor John F. Hartwig, Chair/nThe following dissertation discusses the development and study of palladium-catalyzed C-H/noxidation reactions and cooperative chemoenzymatic reactions./nChapter 1 provides a summary of methods for the synthesis of anilines and related compounds./nAn overview of C-N and C-O bond formation from the reductive elimination of palladium (IV)/ncomplexes is discussed, and the history of allylic C-H acetoxylation is reviewed. A brief/ndiscussion of the types of chemoenzymatic transformations is also included in this chapter./nChapter 2 describes a palladium-catalyzed amination of arenes to form N-aryl phthalimides with/nregioselectivity controlled predominantly by steric effects. The scope and challenges associated/nwith the development of this reaction are discussed./nChapter 3 summarizes mechanistic information about the C-H amination of arenes and describes/nthe synthesis of model complexes to evaluate the possibility of C-N bond formation from the/nreductive elimination of a palladium (IV) intermediate./nChapter 4 describes the development of a palladium-catalyzed oxidation of hindered alkenes to/nform linear allylic esters. The scope and the functional group tolerance of this reaction are/ndiscussed in detail./nChapter 5 describes the development of a new type of cooperative chemoenzymatic system that/ncombines the photocatalytic isomerization of alkenes with enzymatic reduction to generate/nenantioenriched products in high yields and ee’s.

Advisor: Hartwig, John F
Essays in Real Estate Finance and Behavioral Economics

This dissertation consists of two chapters. The first one deals with the information content of bond prices in private label securitization markets. The performance of a security backed by a pool of loans is affected by default correlation, and not only the probability of default. I imply default correlation from the market price of collateralized mortgage obligations. Implied correlations are informative about subsequent bond downgrades, but this information content depends on the quality of documentation on the underlying loans. Correlations implied from junior tranches are no more informative than those of AAA tranches for "low-doc" deals, and the latter no less informative than the former for "full-doc" deals. Errors in computing default correlations were not exclusive to AAA investors./nThe second chapter in this dissertation deals with the structural estimations of utility-based models in a setting of economic decision-making. Dropping the assumption that all individuals are all self-regarding we develop a model of utility maximization under social preferences. We use data from a common pool resource (CPR) game run in the field (1,095 subjects) to estimate a structural model including preferences for selfishness, altruism, reciprocity and equity, identifying preference types using a latent class logit model. Exogenous determinants of type are examined such as socio-economic characteristics, perceptions on the CPR, perceived interest in cooperation among the community, whether the participant does volunteer work and whether the CPR is the household main economic activity of the household. A competing explanation of deviations from Nash equilibrium is the existence of a cognitive factor: the construction of a best reply might make rational expectations about other players’ mistakes (e.g. quantal response equilibrium). We do not find evidence for cognitive heterogeneity. Choice prediction based on types is robust out of sample.

Advisor: Wallace, Nancy
Kermani, Amir
Attosecond Transient Absorption of Solid-State and Phase-Change Materials

Attosecond science, utilizing short bursts of extreme ultraviolet light, has opened up a fascinating new field of ultafast light-matter interactions, where dynamics in atomic, molecular, and solid state systems can now be followed on the timescale of electron motion. In this dissertation, applications of attosecond pulses toward performing transient absorption spectroscopy experiments on complex electron-correlation-driven processes in material systems are described. In the first chapter, a brief overview of ultrafast spectroscopy, attosecond pulse production, and light-matter interaction in the extreme ultraviolet is provided, which offers the necessary breadth and background for the detailed case study that follows, on the insulator-to-metal phase transition in vanadium dioxide./nThe origin of the bandgap in vanadium dioxide, which is not predicted to exist under conventional single-particle band theories, has been explained as the result of either electron correlation or structural distortion. The goal of the experiments presented herein is to use transient absorption spectroscopy with attosecond pulses to characterize the timescale of this process and gain a mechanistic understanding of how it occurs. Because vanadium dioxide is heat sensitive, an apparatus had to be specifically tailored to this type of experiments, and it is described in the second chapter. The results and analysis, including extreme ultraviolet static and time-resolved measurements on both the insulating and metallic phases, are described in the third chapter./nThe second half of this dissertation describes the design and construction of a new vacuum endstation to perform attosecond-pump attosecond-probe measurements, which was constructed and tested at Berkeley and installed at a high power attosecond beamline at the University of Central Florida. Ray tracing simulation and design considerations for the optical layout are described in the fourth chapter, and design of the vacuum endstation, diagnostics, and preliminary experiments and testing can be found in the fifth chapter.

Advisor: Leone, Stephen R
Neumark, Daniel M
Scanning Tunneling Microscopy of Graphene Quantum Dots

Quantum confinement of Dirac fermions is an important frontier in graphene research. In this dissertation, we report on our use of a scanning tunneling microscope (STM) to investigate electrostatically confined Dirac fermions in graphene quantum dots. We first describe a technique for patterning embedded gates in backgated graphene/hexagonal boron nitride (hBN) heterostructures by STM manipulation of defect charges within the hBN substrate. In conjunction with a tunable backgate, this allows us to engineer p-n junctions in monolayer and bilayer graphene whose geometries can be flexibly designed with nanoscale precision. Using scanning tunneling spectroscopy (STS), we image and spatially characterize the behavior of Dirac fermions in the vicinity of p-n junctions and show that circular p-n junctions in monolayer and bilayer graphene act as gate-tunable quantum dots with unique energy spectra. For monolayer graphene quantum dots, comparison with theoretical simulations of the massless Dirac equation enables us to identify each experimentally observed spectroscopic peak as a quantum dot eigenstate with a unique set of quantum numbers. In bilayer graphene, we demonstrate a gate-tunable evolution of locally gated graphene from classical dots to quantum dots and achieve control over the number of massive Dirac fermions contained in a quantum dot by using the STM tip as a top gate. Furthermore, we explore the electronic properties of quantum double dots and non-circular monolayer graphene p-n junctions using spatially resolved STS. Our work yields insight into the spatial behavior of Dirac fermions under the influence of local electrostatic potentials and provides a platform for further experimental investigation of physics related to p-n junctions in graphene.

Advisor: Crommie, Michael F
Towards Improved Mitigations for Two Attacks on Memory Safety

C, C++ and most other popular low-level languages delegate memory management to the programmer, frequently resulting in bugs. Accordingly, a longstanding problem in computer security is efficient, backwards-compatible prevention of the data and control-flow exploits that arise from writing past the end of a buffer or using memory after it has been freed./nIn the first part of this dissertation, we consider protection schemes against the most popular form of control-flow hijacking: return-oriented programming (ROP), which depends on misusing RET instructions. Control-flow defenses against ROP either use strict, expensive, but strong protection against redirected RET instructions with shadow stacks or other dual-stack schemes, or much faster but weaker protections without. We study the inherent overheads of shadow stack schemes (~10%). We then design a new scheme, the parallel shadow stack, with significantly less overhead (~3.5%) and better compatibility. Our measurements suggest it will not be easy to further improve software-only shadow stack performance on current x86 processors, due to inherent costs associated with RET and memory load/store instructions./nNext, we consider defenses against heap use-after-free, which is an increasingly important class of memory safety errors. We show that, in principle, page permissions should be the most desirable approach. We then validate this experimentally by designing, implementing, and evaluating Oscar, a new protection scheme based on page permissions. Oscar does not require source code, is compatible with standard and custom memory allocators, works correctly with programs that fork, and performs favorably --- often by more than an order of magnitude --- compared to recent proposals: overall, it has similar or lower runtime overhead, and lower memory overhead than competing systems./nYesteryear's page-permissions-based allocators, including Oscar, all place one object per virtual page, to allow physical memory to be reclaimed as soon as the object is freed. We revisit this principle in Oscar++: we place multiple objects per page, with a secure quarantine for freed objects on pages that still have other live objects, and efficient inline metadata. On average, this more than halves the overhead for allocation-intensive benchmarks. We also consider the use of object lifetime, to prevent comingling of short-lived and long-lived objects on the same virtual page; this shows some promise for reducing memory overhead from quarantine./nIn the last chapter, we conclude with some lessons and common themes from the three projects.

Advisor: Wagner, David
Maniatis, Petros
Growth Curve Cognitive Diagnosis Models for Longitudinal Assessment

This dissertation proposes longitudinal growth curve cognitive diagnosis models (GC-CDM) to incorporate learning over time into the cognitive assessment framework. The approach was motivated by higher-order latent trait models (de la Torre & Douglas, 2004), which define a higher-order continuous latent trait that affects all the latent skills. The higher-order latent trait can be viewed as the more broadly defined general ability; and the skills can be viewed as the specific knowledge arising from the higher-order latent trait. GC-CDMs trace changes in the higher-order latent traits over time by using latent growth curve model with respondent-specific random intercept and random slope of time, and simultaneously trace students' skill mastery through the CDM measurement model./nGC-CDMs are estimated using marginal maximum likelihood (MML) estimation in Mplus. Relevant issues for estimating GC-CDMs are addressed, e.g., the high-dimensional computation problem, model specification for the relationship between the higher-order latent trait and the multiple skills, and model identification. In simulation studies, we use the DINA measurement model, and examine parameter recovery of the GC-DINA model under differing conditions. Particularly, the effects of the design of the Q-matrix, the number of respondents and the number of time points are discussed. Overall, MML estimation in Mplus shows good parameter recovery; especially, the average growth, which is the parameter of most interest, is well estimated in all conditions. We also illustrate the application of the GC-DINA model to real data using two datasets from multi-wave experiments designed to assess the effects of the Enhanced Anchored Instruction (EAI; Bottge et al., 2003) on mathematics achievement. In addition, the GC-DINA model is compared to the latent transition analysis DINA model (LTA-DINA) (Li et al., 2016; Kaya & Leite, 2016) and a longitudinal item response theory (IRT) model (Andersen, 1985) using a simulated data. The results suggest that the GC-DINA model and the LTA-DINA model are similar in terms of the predicted skill mastery; and the GC-DINA model and the longitudinal IRT model are similar in terms of the predicted higher-order latent trait.

Advisor: Rabe-Hesketh, Sophia