VictorJuiz/thesis huggingface dataset:
Focusing on flat optics : novel fabrication and design processes for high-efficiency silicon metasurfaces

Humanity has long been interested in the manipulation and management of electromagnetic waves, first in the form of refractive optics for visible light and more recently in diffractive optics and over a wider spectrum. The miniaturization of electronics has enabled the production of increasingly smaller patterned objects in a wide variety of materials, and optical device design has taken advantage of these advances. Optical metamaterials are novel thin-film diffractive devices that utilize carefully engineered arrays of subwavelength elements for light management. In this thesis, I discuss several aspects of my research aimed at addressing limitations of experimentally realized metasurface devices. I begin with an introduction to the history of optical devices and an exploration of design techniques for optical metasurfaces before focusing in more depth on my work on dielectric metasurfaces. I then examine the role that material selection plays in metasurface performance, and specifically how crystalline silicon has excellent properties to make efficient flat optical devices operating across the visible spectrum. Next, I explore the application of inverse-design topology-optimization based computational techniques to the design of free-space metasurfaces. This design methodology allows us to access non-intuitive, complex modal dynamics and produce highly efficient high-angle beam deflectors as well as multifunctional and broadband devices. Following this, I discuss work on diffractive optical components that utilize wavelength-scale features, defined by optical lithography, for beam management. Finally, I briefly describe our current efforts towards the design and fabrication of fully topology-optimized aperiodic, multilayer metasurface devices.

Keywords: Applied Physics.
Advisor: Fan Jonathan Albert 
Miller D. A. B. 
Solgaard Olav
The form and function of legal precedent

This dissertation is composed of three distinct but related papers on stare decisis or legal precedent, and employs both empirical and theoretical methods to examine the topic. The first chapter contributes to our understanding of which methods for following precedent do relatively better or worse to serve the values of stare decisis, and under what conditions. The second chapter takes up the precedential value of dissenting opinions, arguing that dissents contribute to the formation of binding precedent in a particular type of plurality decision. The third chapter—through a quantitative, computational study of judicial decisions—reveals substantial and statistically significant relationships between the style of a judicial opinion and its legal influence or precedential power.

Advisor: Landy Joshua
Meyler Bernadette 
Kessler Amalia D. 
Satz Debra
The form and function of relationships in U.S. middle- and working-class contexts : implications for education and health

In this dissertation I examine relationality across social class contexts—i.e., how social class acts as a significant cultural context that shapes the form, function, and meaning of relationships, and the consequences of these relational patterns for important life outcomes, particularly health and education. Part 1 of the dissertation examines social networks, morality, and interpersonal behavior in two social class contexts. I find that working-class contexts tend to be characterized by interdependent relationality in which ties to others are strong, enduring, and supportive, relationships are morally obligating, and behavior should prioritize close others and maintains relationships. Middle-class contexts, in contrast, tend to be characterized by independent relationality in which ties to others are weak and non-permanent, relationships are contingent on individual rights and preferences, and behavior should protect personal goals. Part 2 examines the consequences of interdependent relationality on health. I find that interdependent relationality is more strongly tied to health in working class contexts compared to middle class contexts and that close, trusting, and supportive relationships help reduce social class health disparities. Part 3 focuses on first-generation college students as individuals navigating between working- and middle-class cultures and examines the role interdependent and independent relationality play in promoting positive academic outcomes. I find that successful first-generation students benefit from both types of relationality, suggesting the value of construing first-generation college students as social class biculturals. In sum, compared to higher class contexts, lower class contexts are characterized by scarcity, risks and constraints. However, this work demonstrates that in the absence of economic wealth, close others often act as an important source of social wealth. The interdependence between self and others that is likely to arise from such experiences of mutual support shapes how people understand their world and serves an important role in countering stigma and inequality.

Keywords: Psychology.
Advisor: Markus Hazel Rose 
Eberhardt Jennifer L. (Jennifer Lynn) 
Tsai Jeanne Ling
Former Dual Immersion Students in Spanish 1: Implications of a Disparity Between Elementary Immersion Programs and Secondary World Language Instruction in California Public Schools

My research investigates perceptions of misalignment in students’ educational experiences between dual immersion and traditional secondary world language programs. It analyzes the post-immersion experiences of former dual (two-way) immersion students who were majority group members raised with English at home. Through in-depth interviews with nine former students of an elementary dual immersion program in a California public school district, I explore perceived inconsistencies between the elementary Spanish-English dual immersion program and the district’s middle and high school world language programs. The goals of this study are: a) to understand former dual immersion students’ perceptions of their formal second language instruction and b) to identify any outcomes specific to the combination of pedagogically-differing language programs. Specifically, the study seeks to evaluate the perceived cultivation and engagement of students’ internal language systems in both elementary dual immersion and traditional middle school and high school language classes and understand the relative program impacts on students’ linguistic attitudes, language development, and interpersonal relationships. The study finds that the task of relearning Spanish with a cognitive approach is largely counterproductive since these students have already developed internal linguistic systems through the content-based instruction of dual immersion. Furthermore, the inconsistent transition between programs impedes language development, depreciates previous acquisition, and creates linguistic tensions which manifest themselves in classroom conflict.

Keywords: world (foreign) language instruction
dual (two-way) immersion
student perspectives
Stanford Graduate School of Education
Thesis
Advisor: Valdés Guadalupe
Forming and Informing Perceptions of Controversial Environmental Topics: “How do local landholders in the Finnish Archipelago form and inform their perceptions of wind turbines and their impacts on the white-tailed eagle?”

While the impacts of wind turbines on large raptor populations have been researched extensively (with conflicting results), less is known about how the perceptions of these potential impacts are formed, a topic with implications spanning the human-environmental nexus. Using a case study in the Finnish archipelago, this research addresses how landholders form and inform their perceptions of wind turbines and their impacts on the white-tailed eagle (Haliaeetus albicilla) and surrounding ecosystem. Our team conducted research across three islands, one with wind turbines (Högsåra: N=9) and two without (Attu: N=9, Sorpo: N=12). Thirty randomly selected landholders participated in semi-structured interviews. Questions covered perceptions of the eagles and wind turbines, the forms of media participants relied on, and how they chose whether to trust or distrust relevant information sources. Results demonstrated that most landholders have positive affect toward white-tailed eagles and are fairly evenly split regarding wind turbines. In addition, support or opposition of the turbines appears to be independent of the belief that turbines negatively impact the eagles and is instead predominantly driven by “not in my backyard” (NIMBY) tendencies. When sourcing information, participants tend to trust government-sponsored over industry-sponsored articles, though their opinions often align with the messages published in both. Finally, the research indicated that individual landowners in Finland can hold conflicting opinions despite cognitive dissonance. This case study provides in-depth, rich qualitative data that serves as an insightful addition to reflect similar research regarding human-environmental interactions regarding controversial environmental topics not only in Finland, but across the Western world.

(245 words)

Keywords:  Earth Systems Program
School of Earth Energy and Environmental Sciences
wind turbines
white-tailed eagle
Finland
Earth Systems Program
Thesis
Advisor: Ardoin Nicole
Primmer Eeva
Forming-free aluminum oxide nitride resistive random access memory by atomic layer deposition technique

The demand for high density non-volatile semiconductor storage has been unrelenting. Even though the industry mitigates the fundamental scaling issue of NAND flash by building vertical devices, other technical challenges arise such as high aspect ratio etching, wafer warpage, limitation of cell current, etc. Several emerging nonvolatile memories (NVM), ferroelectric random access memory (FeRAM), spin-transfer torque random access memory (STT-RAM), phase change random access memory (PCRAM) and resistive random access memory (RRAM), are potential replacement for the current technology (SRAM, DRAM or NAND) or can fill the gap of memory hierarchy as a storage class memory (SCM). Among these emerging NVMs, Al/AlOxNy/Al RRAM has demonstrated low programming currents. The entire RRAM stacks were in situ deposited in a physical vapor deposition (PVD) chamber, which lacks the uniformity and limits the flexibility for large scale manufacturing. The motivation of this thesis includes the theoretical study of AlOxNy RRAM, and the experimental result of 1T1R AlOxNy RRAM by atomic layer deposition (ALD). We have simulated that the substitutional doping of nitrogen (Nsub) in Al2O3 is more favorable comparing to the creation of oxygen vacancy (VO) or interstitial doping of nitrogen (Nint). The defect (intermediate) states from the density of states (DOS) facilitate electron hopping through the device. The device structure with Al/AlOxNy/Al is simulated, the electrostatic potential difference and the transmission characteristic shows lower tunneling barrier and higher transmission for RRAM with VO or Nsub, which support the forming-free characteristic of AlOxNy RRAM. The experimental study of Atomic Layer Deposited (ALD) AlOxNy RRAM stacks start with 1R structure. The device structure, doping concentration, film thickness and interface modulation are optimized. Then, we integrate the optimized Al/AlOxNy/ITO stacks on the NMOS wafer, which provides better electrostatic control. The switching parameters such as form/set/reset voltages, set and reset currents, high and low resistance states are statistically characterized with DC measurements. The retention characteristic is examined under high temperature baking. The endurance is measured under AC pulses. In summary, ALD AlOxNy RRAM, with promising programming characteristics and reliability, has been successfully integrated with CMOS.

Keywords: Electrical Engineering.
Advisor: Wong S.
Nishi Yoshio
Wong Hon-Sum Philip
Fostering Innovations by Contextual Empathic Design

This thesis describes the results of a study exploring how user backgrounds can systematically be considered in design activities.
In human-centered engineering design, understanding what users desire and need is key for creating innovative solutions. Uncovering insights of users is needed as a backbone to provide the best possible solution for real customer needs. In this process, it is important to consider the background of users such as their culture, gender, education, or socio-economic class. This thesis is based on a multiple case study of eleven student projects sampled within the past four years of the three-quarter master's level engineering design course ME310 at Stanford University. First, mid- and end-of project reports ranging from 50 to 250 pages were coded from seven projects, chosen after a teaching team session in which the projects were ranked. Four high-performing and three low-performing projects, in which people were seen highly pertinent to the design brief, were chosen for the analysis. A systematic comparison of the methods and strategies reported in each project was performed. Second, four ongoing projects from 2016 were chosen for further study in which people played a large part in the design brief. Students from these four projects were interviewed mid-course on how and why they considered user backgrounds. The interviews were audio recorded and transcribed for analysis, coding each interview for the reported problems and influences for considerations regarding user backgrounds.
The analysis revealed that challenges in considering user backgrounds occur on three different levels: First, teams are not aware of the background of the user as they do not consciously think about it (lack of awareness). Second, they do not understand the user background, even if they are aware of it (lack of empathy). Third, some teams are aware of the background and understand it but do not integrate the knowledge into the design (lack of integration). Especially methods with direct user contact and ones, in which designers immerse themselves in the user perspective are effective as hereby designers rely less on stereotypes and the empathic process is facilitated
These layers were used as a structure for the development of method cards called “Contextual Empathic Design”. “Methods of Discovery” help to create an awareness for user backgrounds. “Methods of Enlightenment” support the process of understanding the backgrounds and “Methods of Integration” help designers to integrate their insights in the solution. The methods created in this research are empirically connected to successful patterns in real design projects and address the most frequent, empirically identified impediments for including peopleness in design. They should enable an advanced human-centered design process that increases the desirability of products by harnessing the potential of background characteristics to better understand users, inform design decisions, and hence foster innovations.

Keywords: design thinking
ME310
product development
user studies
Text
Thesis
Advisor: Böhmer Annette
Sheppard Sheri
Fracture Flow Rate Estimation Using Machine Learning on Temperature Data

Near-wellbore fracture characterization methodologies help in identifying fluid entry points as well as flow rate in order to assess the effectiveness of hydraulic fracturing treatments, optimize the completion plan or identify the need for refracturing. Temperature transient analysis is one of such methods and previous work has shown that it allows for the estimation of flow rate coming out of fractures.
In this work, a machine learning approach to fracture flow rate estimation using temperature data is presented. The problem was formulated as a time series regression problem where the temperature data is used as the input of a reverse model that estimates flow rate. The Lasso Regression, Random Forest and Kernel Ridge Regression algorithms were tested in the study and three case studies are presented with varying levels of complexity.
The Kernel Ridge Regression approach was found to outperform the other two algorithms in the most complex case due to the specific formulation of the features as well as the mathematical similarity of the learning algorithm with the analytical solution of the physical problem.

Keywords:  Energy Resources Engineering
School of Earth Energy &amp; Environmental Sciences
fractures
temperature
machine-learning
Thesis
Advisor: Horne Roland
Free-surface dynamics in the presence of submerged canopies

Seagrasses modify the flow of fluid through and around them at many scales and can completely alter their surrounding fluid environment. This thesis focuses on two cases of the hydrodynamics of canopies in the presence of free surfaces: first, on the free-surface expression of a canopy-generated shear instability; and second, on the role of vegetation in coastal protection in wave-dominated regions. In the first portion, I focus on a new tool and hydrodynamic framework for the remote detection and characterization of submerged ecosystems. Coherent fluid structures shed by the canopy impact the water surface; in the laboratory, we obtained snapshots of the water surface slope over time, showing the emergence of these vortices at the water surface, their propagation downstream, and the length scale of the structures. This imaging method was then used in conjunction with subsurface velocity measurements to make connections between the free surface and interior flow properties, suggesting that a canopy leaves a signature on the water surface that is indicative both of what is beneath the water surface, as well as how it is altering the flow. The final portion of this thesis details laboratory experiments studying the protective benefits of coastal vegetation in altering undertow, turbulence, and free-surface behavior on a sloping beach. Vegetation can redirect or attenuate the undertow current and reduce wave-induced cross-shore transport of turbulent kinetic energy (TKE), suggesting that vegetation may help retain sediment onshore in coastal areas.

Advisor: Koseff Jeffrey Russell 
Ouellette Nicholas (Nicholas Testroet)
Suckale Jenny
From click to boom : the political economy of E-commerce in China

A central question in political economy asks: how do developing states build market-supporting institutions (e.g., secure property rights, contract enforcement, and the rule of law)? Too often, political obstacles prevent developing states from adopting strong formal institutions. I propose that China has devised a novel solution to this political problem: institutional outsourcing. I argue that, with weak rule of law, the state has outsourced part of its institutional functions to key private actors, which I call, private regulatory intermediaries (PRIs). Using as the context China's e-commerce market, where 514 million active users generate more than 70 million transactions per day, I show that online trading platforms (e.g., Alibaba's Taobao.com and Tmall.com) have begun to serve as PRIs. More specifically, platforms privately supply market-supporting institutions to enforce contracts, prevent fraud, and settle disputes. In addition to legal functions, the state has effectively off-loaded a part of social and political functions to platforms. Not only do platforms enforce rules, they also assist the state in creating and reforming formal institutions through institutional experiments. I demonstrate that institutional outsourcing, as an alternative route to institutional development, stimulates growth by enabling large-scale impersonal exchange. And more importantly, institutional sourcing is a more politically viable solution to market failure and governance deficit than the direct reforming of formal institutions. I further show that, China's e-commerce boom carries profound effects on state-business relations, household welfare, and the stability of the authoritarian regime in general. To my knowledge, my dissertation presents the first systematic effort in political economy to study the political implications of e-commerce, an economic force that has revolutionized the way 1.61 billion users trade around the globe. To pursue this endeavor, I employ a mixed methods approach and draw on a variety of original or proprietary data. Qualitatively, I have conducted over 200 interviews during 14 months of fieldwork, supplemented by three years of online ethnographic research. Quantitatively, I analyze original datasets that include the web-scraped information of 1.76 million online stores, an original national survey, and a longitudinal survey on 2,800 households conducted with a large-scale field experiment. The field experiment randomizes first-time e-commerce connection across 100 villages in three Chinese provinces. It helps causally identify the effects of e-commerce on household welfare, rural entrepreneurship, migration, political beliefs, and trust.

Keywords: Political Science.
Advisor: Oi Jean C. (Jean Chun) 
Blaydes Lisa
Tomz Michael 
Weingast Barry R.
From compartments to networks : model complexity and infectious disease policy

The opioid abuse epidemic in the United States calls for new and cost-effective policies to address the rise of morbidity and mortality associated with drug injection. This dissertation explores how, and the extent to which, mathematical modeling can inform policy interventions surrounding HIV for people who inject drugs (PWID). First, we develop a dynamic compartmental model empirically calibrated to the US HIV epidemic to assess the cost-effectiveness of HIV preexposure chemoprophylaxis (PrEP) for PWID. We identify the optimal delivery scenario for PrEP but nonetheless find that it is not likely to be cost-effective. Next, we consider PrEP within a context of other HIV interventions. We find that an optimal portfolio of opioid agonist therapy (OAT), needle syringe exchange programs, and test and treat programs can deliver greater health benefit for less cost than PrEP. Although PrEP averts more infection than OAT, OAT provides more value because of its immediate quality of life improvements for an individual with high competing mortality risks. Finally, to explore how structural modeling assumptions influence policy conclusions, we perform a case study of a potential HIV vaccination across a family of linked models. We find that aggregating individuals into compartments biases us towards intervention, an effect most pronounced when targeting to smaller populations. Parameter complexity, although it has little effect on network models in this context, can mitigate overestimation effects in compartmental models.

Keywords: Management Science and Engineering.
Advisor: Brandeau Margaret L. 
Goldhaber-Fiebert Jeremy D.
Owens Doug