VictorJuiz/thesis huggingface dataset:
Climate extremes in a warming world [electronic resource] : historical trends, physical causes, and response to increasing anthropogenic emissions

Climate and weather extremes cause considerable humanitarian and socio-economic impacts across the globe. Global economic losses from extreme events in recent years are estimated to come close to

Keywords: Environmental Earth System Science.
Advisor: Diffenbaugh Noah S. primary advisor. Thesis advisor
Caldeira K. (Ken)
Field Christopher B. advisor. Thesis advisor
Rajaratnam Balakanapathy advisor. Thesis advisor
Thomas Leif N. advisor. Thesis advisor
Coherent computation in degenerate optical parametric oscillators [electronic resource]

Laws of physics have proved useful for solving combinatorial optimization problems. Simulated annealing and quantum adiabatic evolution are two of the well-celebrated algorithms designed according to fundamentals of statistical and quantum physics, respectively. This doctoral thesis introduces a new type of computing machine taking advantage of principles in quantum optics in hopes of speeding up the computation for some NP-hard problems. The machine is an open dissipative system with degenerate optical parametric oscillators (OPOs) as the basic building blocks. Properties that are considered contributing to the computational ability are the bistability of the output phase of each oscillator, coherent interaction between coupled oscillators, and the inherent preference of the system for oscillating in modes with the minimum photon loss. This thesis establishes a theoretical model for the network and studies its computing power through computational experiments on instances of an NP-hard problem in graph theory with the number of vertices ranging from 4 to 20000. The numerical results clearly demonstrate the effectiveness of the network.

Keywords: Electrical Engineering.
Advisor: Yamamoto Yoshihisa primary advisor. Thesis advisor
Ganguli Surya
Trevisan Luca
Collaborating for people and nature [electronic resource] : assessing the impacts of collaborative governance in federal hydropower licensing

This dissertation evaluates the environmental benefits of collaborative governance, an increasingly common practice in which government and non-state actors share decision-making responsibility in an attempt to make policy decisions more democratic and effective. Despite collaboration's widespread use in environmental management, evidence for its impact on the resources managed is inconclusive. I use the Federal Energy Regulatory Commission's process for licensing hydropower facilities in the US--a five-year process in which an electrical utility, federal and state agencies, tribes, local governments, and non-governmental organizations work jointly to develop the terms of an operating license--as a case to test whether and how varied levels of collaboration affect the environmental quality of licenses. Using a participant survey, document analysis, and process tracing, I find that increased collaboration improved the licenses' environmental quality and implementability, suggesting that collaboration does improve environmental management. The dissertation also considers the mechanism--why collaboration has an effect. I identify that face-to-face deliberation and negotiation most strongly affect environmental quality, providing critical knowledge for the design of collaborative processes. Lastly, the dissertation demonstrates the value of mixing methods to evaluate collaboration, as using multiple data sources and research designs validated my findings and provided a more holistic view of how collaboration works.

Advisor: Ortolano Leonard primary advisor. Thesis advisor
Thompson Barton H.
Ardoin Nicole M. (Nicole Michele) advisor. Thesis advisor
Freyberg David L. advisor. Thesis advisor
Collider constraints on the phenomenological MSSM with neutralino and gravitino lightest supersymmetric particles [electronic resource]

As the Large Hadron Collider (LHC) begins Run II collisions at an unprecedented 13 TeV center-of-mass collision energy, it is important to take stock of the lessons learned from the Higgs discovery and the null results from searches for new physics, and also to understand how the LHC fits within the framework of rapid progress in flavor physics, dark matter detection, and cosmology. In this Thesis, I describe a numerical study of phenomenological MSSM (pMSSM) models, considering models with either of the two viable choices (a neutralino or a gravitino) for the lightest supersymmetric particle (LSP). After considering constraints on these models from flavor physics and early universe cosmology and exploring the relationship between model phenomenology and fine-tuning, I will describe how the viable parameter space is affected by LHC Run I searches, compare our results with simplified model exclusion limits, and describe important cases where the pMSSM results differ from simplified model analyses. I will also highlight cases where the LHC limits are degraded as a result of unusual decay topologies and/or displaced decays, discuss ways to improve the LHC's sensitivity to these scenarios, and show preliminary projections for the anticipated improvement in sensitivity that will result from the increased energy and luminosity in Run II. Finally, I will investigate how precise measurements of the couplings of the Standard Model - like Higgs can provide a complementary approach for exploring the pMSSM parameter space.

Keywords: Physics.
Advisor: Hewett JoAnne L. primary advisor. Thesis advisor
Peskin Michael Edward
Rizzo Thomas
Collision avoidance up to the handling limits for autonomous vehicles [electronic resource]

As autonomous vehicles enter public roads, they should be capable of using all of the vehicle's performance capability, if necessary, to avoid collisions. This dissertation focuses on facilitating collision avoidance for autonomous vehicles by enabling safe vehicle operation up to the handling limits. The new control approaches first rely on a standard paradigm for autonomous vehicles that divides vehicle control into trajectory generation and trajectory tracking. A trajectory generation approach calculates emergency lane change trajectories, defined in terms of path curvature, that allows an autonomous vehicle to perform emergency lane changes up to its handling limits. Analysis also provides insights into when and to what extent a vehicle should brake and turn during an emergency lane change to maximize the number of situations in which a collision can be avoided. However, experimental results also highlight vehicle stabilization challenges associated with tracking paths defined by high rates of curvature change, which are desirable for emergency maneuvers. A link is forged between path curvature and vehicle performance, which inspires two trajectory tracking control designs. A four-wheel steering controller adds rear steering actuation to improve tracking and stabilization performance, while a two-wheel steering predictive controller incorporates future path information into current control actions. Experimental results demonstrate the advantages of each approach. However, separating vehicle control into trajectory generation and tracking is not always conducive to emergency maneuvers up to the vehicle's handling limits, where these aspects of vehicle control become tightly coupled with each other and with vehicle stabilization. An alternative paradigm is suggested that is more adept at controlling the vehicle in such scenarios. This approach integrates trajectory generation, trajectory tracking, and vehicle stabilization into one controller capable of mediating among the sometimes conflicting demands imposed by collision avoidance and stabilization. The controller can prioritize collision avoidance, above even stabilization, to minimize potential collisions. Experimental emergency lane changes and a mid-corner obstacle avoidance scenario highlight the advantages of this integrated approach to vehicle control.

Keywords: Mechanical Engineering.
Advisor: Gerdes J. Christian primary advisor. Thesis advisor
Mitiguy Paul
Pavone Marco
Commitment, vertical restraints, and dynamic pricing of durable goods [electronic resource]

Fixed price agreements are common in book markets. The agreements are industry wide and let the publisher set the retail price for a limited period. A natural experiment in the Norwegian book market weakened the vertical restraints in the Norwegian fixed price agreement. The fixed price period was shortened and the price restraint was softened to allow some retailer discounting. Two pronounced changes in the sales followed: The prices unravelled, and demand shifted from early at high prices to later at lower prices. The observed changes are not directly consistent with the traditional rationales for resale price maintenance, but instead show a loss of commitment. The commitment effects are quantified in a dynamic market equilibrium model with forward looking demand side and a forward looking supply side with a vertical structure at parameters estimated from the data. The analysis estimates the commitment effect of the fixed price agreement to be on the order of 2% beyond what resale price maintenance alone can explain.

Keywords: Business.
Advisor: Nair Harikesh S. (Harikesh Sasikumar)
Benkard C. Lanier advisor. Thesis advisor
Hartmann Wesley R. (Wesley Robert)
Compact and efficient subharmonic OPOs for optical frequency comb applications [electronic resource]

Optical frequency combs have become useful for applications in the mid-infrared such as frequency metrology and molecular spectroscopy. One tool for converting the infrared (IR) spectrum to the mid-infrared is the optical parametric oscillator (OPO). Specifically, the OPO operating at degeneracy, or the subharmonic of the pump, has been shown to preserve the salient frequency comb properties of the pump during the nonlinear conversion process. Previous demonstrations of subharmonic OPOs have generated broad bandwidths with low threshold requirements, however conversion efficiencies have been limited. Additionally, because femtosecond OPOs operating at degeneracy are generally synchronously pumped systems, the cavity lengths are typically constrained by the repetition rate of the pump laser. This dissertation presents the experimental results of three novel methods for implementing a synchronously pumped subharmonic OPO. The three designs are built around similar ring-resonator cavities. The designs focus on (i) increasing the OPO conversion efficiency to > 60%; (ii) reducing the overall size, or footprint, of the OPO using an optical fiber cavity while preserving < 100 fs operation; and (iii) increasing the repetition rate while also reducing the footprint of the OPO. First, a synchronously pumped subharmonic OPO was designed around a doubly resonant cavity. The nonlinear gain medium was a periodically-poled lithium niobate crystal designed to convert femtosecond pulses from a commercial 1-micron mode-locked fiber laser to 2 microns. Using high output coupling, the subharmonic OPO generated pulses as short as 40 fs with more than 600 mW of average output power and over 70% conversion efficiency. The synchronously pumped subharmonic OPO cavity was redesigned using single-mode optical fiber as a feedback loop in the cavity. Using two-types of optical fiber, exhibiting normal and anomalous dispersion, respectively, the OPO produced sub-100 fs pulses, generated a broad bandwidth, and achieved almost 40% conversion efficiency. The final design of a synchronously pumped subharmonic OPO cavity was built using a fractional length cavity design. A commercial mode-locked fiber laser operating at 100-MHz pumped an OPO cavity that was 1/5 the length of the typical synchronously pumped cavity length and generated a 500-MHz repetition rate signal.

Keywords: Electrical Engineering.
Advisor: Byer R. L. (Robert L.)
Digonnet Michel J. F. advisor. Thesis advisor
Miller D. A. B. advisor. Thesis advisor
Comparative analysis of CO₂ capture systems [electronic resource] : an exergetic framework

A portfolio of technology strategies will be needed to reach overall greenhouse gas emissions targets. Implementing systems to separate CO2 from atmospheric emissions of fossil-fuel power plants is predicted to be a necessary part of this portfolio, especially in the near term. However, existing carbon capture systems are quite inefficient, using or otherwise reducing a significant portion of power plants' electricity output. In order to improve future systems and make them viable, it is important to understand which aspects of each system have the most potential to improve, and which systems overall are most promising for future research and development. In this work, we examine three representative options for CO2 capture systems. The first option, an amine absorption system for post-combustion capture, is studied due to its relative technological maturity. The second system uses vacuum-swing adsorption and is examined as a post-combustion alternative to the amine system. The third option is a novel system using oxyfuel combustion in supercritical water, which facilitates CO2 separation while reducing the irreversibility inherent in fuel combustion. For each of these options, the current state of the system is modeled and assessed, and the potential for improvement of the system's efficiency is identified and discussed. This assessment is done via an exergy analysis, for several reasons. First, an exergy analysis provides a direct way to compare each process or unit operation to its thermodynamically optimal limit. This gives an immediate sense of how much improvement is actually still possible, thermodynamically, in that process or unit operation. Second, exergy analysis is a useful tool to compare---on a common basis---systems that use different types of inputs (heat vs. work vs. matter transfers), such as the three systems studied here. The first goal of this work is to give targeted recommendations for each type of system---and to discuss potential limitations---based on the results of the exergy analyses. A second goal of this work is to provide the correct theoretical modeling framework to allow an exergy analysis of these types of systems. Because each of these systems deal with non-standard fluids, calculation of thermodynamic properties relevant to performing an exergy analysis of these systems is not trivial. The relevant thermodynamic theory is extended where necessary, in particular in the case of the adsorption system.

Keywords: Mechanical Engineering.
Advisor: Edwards C. F. (Christopher Francis) primary advisor. Thesis advisor
Brandt Adam (Adam R.) advisor. Thesis advisor
Mitchell Reginald advisor. Thesis advisor
Competing and cooperating phenomena in high temperature superconductors [electronic resource]

In solid state physics, the presence of electron interactions leads to many interesting collective behaviors, such as superconductivity and magnetic and charge ordering. In particular, high temperature superconductors exhibit competing and cooperating phenomena due to the importance of charge, spin, structure, and orbital degrees of freedom. For iron pnictide superconductors, in some cases, their deep interplay may be present in experimental observations but only realized by accompanying theoretical considerations. In iron pnictides, mean field and T-matrix formalism expose the potential of tunneling experiments to deeply probe magneto-orbital cooperation. Additionally, angle-resolved photoemission displays the phenomenology of coexistent superconductivity and magnetism, which mean field considerations show to be a signal of fundamental competition between these two orders. Similarly, time-resolved X-ray diffraction displays structural deformations, the cooperative implications of which are revealed by considering the mean field effects of this deformation on magnetism. Finally, the focus shifts to fundamental studies of extended Hubbard models on superconductivity, where numerical exact diagonalization reveals competing charge phenomena. To understand interacting electron systems, experiments are vital, and sometimes a true appreciation is gained by accompanying theoretical studies.

Keywords: Applied Physics.
Advisor: Devereaux Thomas Peter
Fisher Ian R. (Ian Randal) primary advisor. Thesis advisor
Kivelson Steven advisor. Thesis advisor
A computational account of social reasoning [electronic resource] : towards a more realistic model of theory of mind

This thesis develops and tests a unified framework for computational models of how people use their theory of mind (ToM) to reason about others. I begin by using the framework to highlight the core formalization of how people choose actions based upon their beliefs and desires, a formalization common to previous models of social reasoning. I then discuss how the compositional nature of this framework allows it to incorporate more sophisticated models of people's mental states. The framework makes quantitative predictions about how people using these models of ToM should learn and reason about others. In the remainder of this thesis I use the framework to develop a more realistic model of people's ToM. I first examine a set of extensions to the current models of ToM---how people reason about others' attributes like how knowledgeable, reliable, and confident they are. I find that this elaborated model captures how changes in a person's attributes affects how others learn from them and the inferences they make about them. I then examine a core assumption made by previous accounts of ToM---that people form beliefs independent of their desires. I show that people think that others wishfully think, letting their desires affect their beliefs. Incorporating this wishful thinking into the model highlights the profound impact the details of a person's ToM has on their social reasoning. If a person thinks that others wishfully think, then the other's desires should have an impact on how the person learns from them. Indeed, people followed the pattern predicted by the model. They learned more from someone who bets against their desires. Finally, I conclude by describing both the challenges to the framework and how its extensibility can allow future models to overcome these limitations and provide increasingly realistic models of mind.

Keywords: Psychology.
Advisor: Goodman Noah (Noah D.) primary advisor. Thesis advisor
Frank Michael C. (Professor of human biology) advisor. Thesis advisor
Monin Benoît
Computational approaches to scaling up experimental science [electronic resource]

Low statistical power reduces the likelihood of detecting true effects and produces unreliable research with low reproducibility of results, but resource constraints limit sample sizes when resource requirements scale linearly with sample size. This work applies computational methods to scaling up experimental science, affecting experimental design, data collection and analysis. In the domain of gene expression measurements, costs are reduced by selecting reduced probe sets and imputing the remaining probes. Evaluation of the methods developed here in a wide variety of experimental settings shows that linking selection and imputation in a unified objective allows for considerable cost reductions with small information loss, and the approach is further validated in a large-scale study of immune system variation. Two additional applications of computational methods scale up cognitive testing and modeling of human learning dynamics.

Advisor: Shoham Yoav primary advisor. Thesis advisor
Batzoglou Serafim advisor. Thesis advisor
Kosslyn Stephen Michael
A computational framework incorporating human and social behaviors for occupant-centric egress simulation [electronic resource]

Emergency evacuation (egress) is an important issue in safety design of buildings. Studies of catastrophic incidents have highlighted the need to consider occupants' behaviors for better understanding of evacuation patterns. Although egress outcomes are influenced by human and social factors, quantifying these factors in design codes and standards is difficult because occupants' characteristics and emergency scenarios vary widely. As an alternative, computational egress simulation tools have been used to evaluate egress designs. However, most of current simulation tools oversimplify the behavioral aspects of evacuees. This thesis describes a flexible computational framework that incorporates human and social behaviors in simulations to aid occupant-centric egress design. Based on the analysis of literature in social science and disaster studies, the design requirements of SAFEgress (Social Agents For Egress), an agent-based simulation framework, are derived. In SAFEgress, the agent's decision-making process, the representation of the egress environment and the occupants, and the algorithms that emulate human capabilities in perception and navigation are carefully designed to simulate group dynamics and social interactions. A series of validation tests has been conducted to verify the capability of the framework to model a wide range of behaviors. Case studies of a museum and a stadium show that considering group navigation could cause additional bottlenecks on egress routes, thus prolong evacuation. On the other hand, by strategically arranging stewards to control crowd flow, evacuation time can be significantly improved. SAFEgress provides a means to systematically evaluate the effects of human and social factors on egress performance in buildings and facilities. Using the simulation results, facility managers and designers can develop occupant-centric solutions to crowd problems by addressing different scenarios and unique occupants' characteristics. Furthermore, the framework could be applied to support research in social science to investigate the collective behaviors of crowds in a built environment.

Keywords: Civil and Environmental Engineering.
Advisor: Law K. H. (Kincho H.) primary advisor. Thesis advisor
Parigi Paolo
Latombe Jean-Claude advisor. Thesis advisor