VictorJuiz/thesis huggingface dataset:
Diffusion of designerly finite element analysis [electronic resource]

To address a variety of difficulties surrounding the use of finite element analysis (FEA) in product development at Sandia National Laboratories, this research explored a 'designerly' insertion of FEA into the design-build-test product development cycle. Designerly FEA is characterized by the use of simplified FEA models, designer-friendly FEA software, an FEA analyst embedded in the product design team, relative comparisons of design options, and a deliberate leveraging of routine prototype testing to collect model validation data. Two case study projects were used to explore the impact of this approach on the product development teams' thinking and perceptions of FEA. The case study data was collected using a variety of methods and analyzed using a theory-building approach. The results were synthesized into a framework that describes how the use of FEA to build confidence in a product design is related to the process by which product development teams gain or lose confidence in FEA itself. The implications may extend to other organizations that desire to increase the impact of FEA or other simulation technologies in their product development process.

Keywords: Mechanical Engineering.
Advisor: Sheppard S. (Sheri) primary advisor. Thesis advisor
Law K. H. (Kincho H.) advisor. Thesis advisor
Leifer Larry J. advisor. Thesis advisor
Directed self-assembly for nanofabrication and device integration [electronic resource]

For more than 50 years, the size of the semiconductor devices has been scaling by approximately a factor of two every 1.5-2 years. This has brought tremendous benefits for the industry including lower cost per transistor, more computing power and higher speed. However, it has been recently observed that the scaling of devices is approaching fundamental (i.e. atomic scale) and economic (i.e. cost per fabrication facility) limits, in large part because traditional lithography is facing substantial challenges for printing the shrinking features while maintaining a reasonable cost. In response to this urgent need, researchers are actively searching for alternative patterning approaches as the next generation lithography. Potential solutions such as extreme ultraviolet lithography, electron beam lithography, and multiple patterning lithography have attracted much attention from the lithography community. However, each one of these solutions has its own drawbacks, such as extremely high cost or low throughput. Among these solutions, block copolymer directed self-assembly (DSA) stands out due to its low cost, high throughput, well-controlled sub-20 nm features, and experimentally demonstrated potential to scale below 14 nm. Block copolymers are unique soft materials that can self-assemble through microphase separation into various periodic nanostructures such as cylinders, spheres and lamellas, driven by the incompatibility between the different blocks. The feature size of these nanostructures is dependent on the molecular weight of the block copolymers and therefore not limited by the same factors that limit optical lithography such as ultraviolet light wavelength. In addition, the self-assembly could be controlled by a simple thermal annealing process, which significantly reduces the cost and improves the throughput. Among all the varieties of nanostructures, the cylindrical self-assembled patterns are especially suitable for patterning contacts and vias in integrated circuits (ICs). This dissertation focuses on the application of block copolymer DSA for contact hole patterning in ICs. This work first demonstrates the flexible control of aperiodic DSA patterns using small physical guiding templates, using both experiments and computational simulations. This is followed by the first patterning example of memory and random logic circuit contacts using DSA. To enable practical technology adoption, I introduce an alphabet approach that uses a minimal set of small physical templates to pattern all contact configurations on integrated circuits. This work also illustrates, through experiments, a general and scalable template design strategy that links the DSA material properties to the technology node requirements. Last but not least, the dissertation introduces a method to reduce DSA defectivity by using sub-DSA-resolution Assist Features (SDRAFs).

Keywords: Electrical Engineering.
Advisor: Wong Hon-Sum Philip
Fan Jonathan Albert
Pop Eric advisor. Thesis advisor
Discovering entrepreneurial opportunities [electronic resource] : individual, team and organizational capabilities

The discovery of profitable entrepreneurial opportunities is a challenging endeavor. Even for expert entrepreneurs and investors. Particularly in high-growth, dynamic and uncertain environments. I begin by analyzing empirical literature in the fields of entrepreneurship, strategy and institutions to explain where opportunities emerge in time and space, and which unique behaviors help to discover them. Next, I empirically explore how individuals, teams and organizations can develop the capabilities to discover high-value opportunities. My first empirical study shows how entrepreneurs can acquire these capabilities by interacting with the right peers. The second study shows how team composition aids the necessary cognitive flexibility during the discovery process. My final study shows how organizations can use rational heuristics to discover and accurately predict high-potential ventures. I explore these questions by studying two novel entrepreneurship policies: Start-Up Chile and I-Corps.

Keywords: Management Science and Engineering.
Advisor: Eesley Charles primary advisor. Thesis advisor
Eisenhardt Kathleen M. advisor. Thesis advisor
Katila Riitta advisor. Thesis advisor
Dissociating cognitive and behavioral functions of the human striatum [electronic resource]

The striatum, initially identified as a primarily motoric structure, is now known to facilitate many cognitive functions, including learning, motivation, and the experience of reward. Although the striatum's involvement with these functions is well established, uncertainty remains regarding the structural and functional neural pathways that give rise to these capacities. Here, we present results from functional imaging experiments on human participants that were designed to dissociate the processes supported by striatal subregions. Across two studies, we show that the dorsal and ventral striatum contribute to distinct aspects of behavior and cognition: whereas the ventral striatum is associated with reward processing and model-free learning, the dorsal striatum is more involved in the initiation of motivated actions and learning abstract behavioral rules.

Keywords: Psychology.
Advisor: McClure Samuel M. primary advisor. Thesis advisor
Goodman Noah (Noah D.) advisor. Thesis advisor
Knutson Brian advisor. Thesis advisor
Divided Intentions: Iraqi Nuclear Weapons Policy Between the First and Second Gulf Wars

Contrary to common belief, Saddam Hussein did not intend to deceive UN inspectors and the international community concerning his nuclear weapons program between the First and Second Gulf Wars; rather, internal discussions between Hussein and his ministers indicate that they desired cooperation with inspections so that sanctions would be removed. However, it is also clear that the overriding belief held by the Iraqi government was that the United States was a nearly omnipotent threat that was completely controlling the UN Security Council and the UN inspections teams. They believed that the United States was intentionally prolonging inspections to keep sanctions on Iraq as a means to weaken the state in preparation for a future invasion aimed at regime change. This belief was present at every stage of inspections after the First Gulf War, but did not significantly alter Hussein’s strategic intent to cooperate. Nevertheless, it is clear that elements in the Iraqi government did deceive UN inspectors by intentionally hiding information about the nuclear weapons program and failing to cooperate with inspectors when they arrived in Iraq. However, deception appears to have been carried out by members of the Iraqi government subordinate to Hussein and his cabinet without their knowledge. The case of Iraqi nuclear weapons policy from 1991-2003 demonstrates the difficulty in understanding the strategic intent of foreign governments, especially when a seemingly centralized government actually allows a high level of autonomy to the non-cabinet level officials that actually carry out the regime’s policy.

Keywords:  Program in International Relations
Iraq
Nuclear Weapons
Weapons of Mass Destruction
Gulf War
Deception
UNSCOM
Inspections
Disarmament
International Security
Center for International Security and Cooperation
International Security Honors
International Relations
Thesis
Advisor: Sagan Scott
Does Ethnic Fractionalization Matter for Development?

An existing literature finds that ethnic fractionalization (a measure of ethnic diversity) is negatively correlated with various development outcomes, including growth and public goods provision (Alesina and La Ferrara, 2005). This paper attempts to deal with issues of endogeneity in work related to ethnic fractionalization. I develop an instrument for fractionalization based on the arbitrary construction of African borders, and also use a control function approach to deal with omitted variables bias. Both methods generate evidence that the endogeneity of ethnic fractionalization causes substantial bias in regressions of growth on fractionalization, and the true effect substantially smaller, although very difficult to estimate precisely. I develop a game theoretic model to explain how to reconcile micro-level evidence of harmful ethnic favoritism with macro-level effects of ambiguous sign.

Keywords:  Department of Economics
Stanford Department of Economics
Thesis
Advisor: Dupas Pascaline
Driver adaptation to changes in automobile handling properties [electronic resource]

Automobile drivers frequently encounter changes in vehicle handling properties that require them to adjust their steering control actions. These changes may be benign, such as slightly different steering ratios in different cars, or potentially life-threatening, such as suddenly encountering a patch of black ice on the roadway. Understanding how drivers adapt to such handling changes is important for informing the design of new driver assistance systems and training methods. Although adaptation has been studied extensively in the laboratory for applications such as arm reaching and walking, there are still many unanswered questions about the adaptation process in the context of driving. This dissertation addresses the need to understand how drivers adapt to handling changes by designing and implementing a novel user study with an experimental vehicle. Drivers complete several trials of a lane change task while the vehicle handling properties are mod- ified in one of four ways that represent scenarios similar either to common laboratory ex- periments from arm reaching studies or to real-world situations specific to driving. The specific handling changes are (1) scaling the steering ratio, (2) reversing the steering direc- tion, (3) scaling the steering wheel torque, and (4) simulating low friction vehicle dynamics. To enable the latter type of handling change, a new approach to handling modification has been developed using online simulation of the dynamics and tire forces of a reference vehicle model. The resulting control scheme provides a method of emulating a range of planar vehicle dynamics, in particular those of a vehicle traveling on an icy road. The results of user studies with the four handling modifications demonstrate that adaptation exists in automobile steering control tasks. The studies provide evidence that drivers adapt their steering control based on steering wheel angle, not on steering wheel torque. Finally, individual driving style influences the degree of adaptation necessary when encountering a low friction surface.

Keywords: Mechanical Engineering.
Advisor: Gerdes J. Christian primary advisor. Thesis advisor
Okamura Allison advisor. Thesis advisor
Rock Stephen
Drosophila melanogaster natural variation affects infection and microbial growth dynamics when infected with Listeria monocytogenes [electronic resource]

The immune response is a dynamic system, which balances microbe killing with host health. In this dissertation I used a Drosophila melanogaster -- Listeria monocytogenes model to define parameters that define the dynamics of infection, and to measure the variance of these key parameters. In Chapter 2, I performed a screen to identify genes that affect the phenotypic natural variation of host survival and pathogen growth control after an infection. In Chapter 3, I investigated the shape of disease- tolerance curves, which summarize infection outcome by plotting health by microbe load. We found tolerance curves are sigmoid, and can be warped in predictable ways. Using this information, we defined a simple mathematical model of infection comprised of three parameters: microbial growth, immune activation and host health. In Chapter 4, I report experiments that focused on microbe growth, measuring how fly genetic variation alters Listeria growth curves. I found microbe growth curves changed in two ways: maximal growth rate and/or growth plateau. I found that these two growth parameters could change independently and both affected host health. This work provides a foundation for a dynamic model of immunity, which is essential to explain how the balance between microbe killing and host health is maintained.

Keywords: Microbiology and Immunology.
Advisor: Schneider David (David Samuel)
Kirkegaard Karla advisor. Thesis advisor
Monack Denise M. advisor. Thesis advisor
Mudgett Mary Beth
Dynamic models of electron transport in hall thruster simulations [electronic resource]

The Hall-effect thruster (HET) is an electrostatic propulsion device that relies on the Hall effect to generate a dense ExB electron current to ionize the propellant gas. In simulating Hall thrusters, describing electron cross- eld transport has been one of the greatest challenges because the electron transport in a Hall thruster is anomalously higher than that predicted by classical collision theory. Researchers have suggested some explanations of the anomalous transport, but they have failed to establish a reliable physical model for general applications. Establishing a physical model that is applicable to various types of Hall thrusters in various operating conditions is an objective of this work. In this thesis, a 2-D hybrid particle-in-cell (PIC) simulation for the Stanford Hall thruster (SHT) is used to implement the transport (electron mobility) models. Among various attempts, an entropy closure model, as well as a turbulent transport model were successfully implemented and demonstrated results that show reasonable agreement to measured data. The entropy closure model uses a 1-D entropy transport equation in the plasma of a Hall thruster discharge to derive a relation for electron mobility as a function of other plasma properties. The simulated results show a reasonable agreement with experiments. The turbulent transport model seeks for a more straightforward way to incorporate the entropy production mechanism into the simulation. By assuming that the Joule heating is the main source of entropy production, we adopted the turbulent kinetic theory to relate the energy dissipated from the largest eddies with the energy production rate. Through a scaling analysis, electron mobility is expressed as an explicit function of other plasma properties of the simulation. The simulated electron mobility captures the electron transport phenomenon measured experimentally. To test the transportability of the turbulent model, the simulation was modi ed for an SPT-type thruster with a different geometry than the SHT. Also, an alternative propellant, molecular nitrogen, was simulated on the geometry of the SHT using the turbulent model. The dynamic mobility models make it possible to observe the dynamic characteristics of the Hall thruster. The mobility models in this study magnify the capability of Hall thruster simulations to explore design space cost effectively.

Keywords: Mechanical Engineering.
Advisor: Cappelli Mark A. (Mark Antony) primary advisor. Thesis advisor
Gascon Nicolas
Ihme Matthias
Economies of expertise [electronic resource] : knowledge and skill transfer in classical Greece

How did 4th-century autocrats like Philip II of Macedon (or Mausolus of Caria, etc.) import expertise from Greek city-states? The evidence available to us indicates they did do this----deliberately and quickly----and so the mystery becomes: how? It is particularly mysterious in light of modern studies that show substantive expertise transfer to be very challenging (see, for instance, the field of development economics). This dissertation offers an answer to this problem: the new capacity of states for expertise transfer was made possible by new frameworks for understanding expertise, developed mainly at Athens (for instance, in the works of Thucydides, Plato, and Aristotle), but disseminated to Greek speaking autocrats over the course of the 4th-century. These new accounts----centered on notions like technē, epistēmē, and empeiria----opened up new possibilities for 4th-century monarchs, allowing them to pinpoint technical fields they wished to target, capture, and recreate (something impossible in absence of an agreed upon, well- developed language of expertise). Plugging into a Greek world of high specialization and expert mobility, opportunists like Philip were thus able to rapidly develop state capacity in fields like land and sea warfare, siege engineering, fortification building, and fiscal administration, allowing them to compete with, and eventually dominate, the Greek city-states.

Keywords: Classics.
Advisor: Ober Josiah primary advisor. Thesis advisor
Morris Ian
Netz Reviel advisor. Thesis advisor
The effects of cover crops on phosphorus cycling in agricultural soils of California [electronic resource]

Phosphorus (P) limits agricultural productivity because most soil P is found in pools of low plant-availability and external inputs that are used to increase plant-available P are only partially recovered in crops, resulting in low P use efficiency (PUE). Cover crops could reduce external P input requirements, increase PUE and stimulate soil P cycling by mobilizing soil P and by retaining soil P via plant uptake, especially in low-input agricultural systems. This dissertation seeks to determine if cover crops have similar effects on soil P cycling in intensive agricultural systems with relatively high soil P, using two long-term experiments in California, greenhouse experiments and nutrient budgets. In both field and laboratory conditions, legume cover crops had a greater potential to mobilize soil P than other cover crops, although in practice they did not mobilize soil P. In contrast, cereals had the strongest effect on soil P availability and P cycling by taking up more soil P than other cover crops. Regardless of cover crop type, P taken up in cover crop biomass was recycled rapidly in these systems: cover crop residues and mineral fertilizer contributed similarly to soil pools and wheat P uptake, with a greater contribution at lower soil P availability. However, cover crops had relatively small effects on long-term soil P dynamics relative to compost addition that was the main factor driving differences in P budgets computed at the farm-scale. Overall, cover crops have the potential to affect soil P cycling in these systems with relatively high soil P, although to a lesser degree than do composts.

Keywords: Biology.
Advisor: Vitousek Peter Morrison primary advisor. Thesis advisor
Fendorf Scott advisor. Thesis advisor
Field Christopher B. advisor. Thesis advisor
Scow Kate M. advisor. Thesis advisor
Effects of TLR9-Dependent Activation of Plasmacytoid Dendritic Cells on Post Stroke Recovery

Stroke is a leading cause of human disability and death, yet continues to lack an effective treatment, as well as a thorough understanding of its pathological mechanisms. Currently, the post-stroke immune response is believed to be a pathological mechanism that exacerbates tissue damage and inhibits recovery. Within the immune system, a relatively rare leukocyte known as the Plasmacytoid Dendritic Cell (pDC) has been demonstrated to produce a disproportionately large amount of type 1 IFNs and pro-inflammatory cytokines through a TLR9-dependent pathway. Consequently, it is thought to serve as an orchestrator of the immune response. Therefore, this project sought to answer the question: How does pDC activity affect recovery after stroke? To answer this question, the effect of pDC activation via the TLR9-dependent pathway on post-stroke recovery was examined through usage of the widely accepted Middle Cerebral Artery Occlusion (MCAO) mouse model for stroke induction, the rotating beam test to assess recovery of motor function, neurological scoring, and confocal microscopy to visualize pDCs within the brain after stroke. It was found that activation of pDCs via the TLR9-dependent pathway leads to increased (statistically insignificant) infarct size. As well, pDC depletion facilitates short-term motor function recovery (partially significant), and a decrease in long-term development of infarct (statistically insignificant). This research is novel because it places pDC activity within the context of the post-stroke immune response, and has translational potential through elucidating a neuropathological mechanism of stroke.

Keywords:  Department of Biology
Stroke
pDC
Thesis
Advisor: Heng Zhao
Jones Patricia
Efficient algorithms for Personalized PageRank [electronic resource]

We present new, more efficient algorithms for estimating random walk scores such as Personalized PageRank from a given source node to one or several target nodes. These scores are useful for personalized search and recommendations on networks including social networks, user-item networks, and the web. Past work has proposed using Monte Carlo or using linear algebra to estimate scores from a single source to every target, making them inefficient for a single pair. Our contribution is a new bidirectional algorithm which combines linear algebra and Monte Carlo to achieve significant speed improvements. On a diverse set of six graphs, our algorithm is 70x faster than past state-of-the-art algorithms. We also present theoretical analysis: while past algorithms require Omega(n) time to estimate a random walk score of typical size 1/n on an n-node graph to a given constant accuracy, our algorithm requires only O(m) expected time for an average target, where m is the number of edges, and is provably accurate. In addition to our core bidirectional estimator for personalized PageRank, we present an alternative algorithm for undirected graphs, a generalization to arbitrary walk lengths and Markov Chains, an algorithm for personalized search ranking, and an algorithm for sampling random paths from a given source to a given set of targets. We expect our bidirectional methods can be extended in other ways and will be useful subroutines in other graph analysis problems.

Advisor: Garcia-Molina Hector primary advisor. Thesis advisor
Goel Ashish primary advisor. Thesis advisor
Leskovec Jurij advisor. Thesis advisor