VictorJuiz/thesis huggingface dataset:
Mechatronic Considerations on the Development of an Upper Limb Exoskeleton for Rhesus Macaques

Integrating an exoskeleton as the external apparatus for a brain-machine interface has the advantage of providing multiple contact points to determine body segment postures and allowing control to and feedback from each joint. Most current brain-machine interface studies use non-human primates, for example rhesus macaques (Macaca mulatta), as the research subjects. In order to develop an upper limb exoskeleton for macaques which can provide both data acquisition and motion actuation, this dissertation investigates the mechatronic considerations of developing such a device, including 1) the kinematic modeling and structural design, and 2) the actuator design and control./nAn exoskeleton is a wearable robot, and is supposed to be attached to the user's body segments. Thus the kinematic structure needs to match the macaque's upper limb as closely as possible, which requires the exoskeleton to be compact and singularity free in workspace, as well as have biomorphic nature joints and firm attachments. In order to provide sufficient output torque and guarantee the user's safety, the actuators of the exoskeleton should be backdrivable, of high power-to-weight ratio, and capable of executing compliant actuation algorithms./nBased on the above design requirements, this dissertation presents the development process of an upper limb exoskeleton for macaques from kinematic modeling and analysis, passive exoskeleton prototyping and animal training, compliant actuator design and control, to completion of an actuated exoskeleton and system integration with a brain-machine interface. First an upper limb exoskeleton model is proposed with a redundant shoulder joint to achieve improved manipulability than conventional designs. The advantageous features of the proposed exoskeleton model are demonstrated by a series of kinematic analysis. Then a passive upper limb exoskeleton is fabricated for kinematic model validation, motion characterization and animal training purposes, and its effectiveness is demonstrated by the animal tests. In order to obtain a compact, powerful, backdrivable and torque-reflecting actuator for the actuated exoskeleton, a cable-driven series elastic actuator is designed, and an interactive impedance control algorithm is proposed and experimentally validated. On top of the development of the passive exoskeleton and the impedance-controlled actuator, an actuated multi-degree of freedom upper limb exoskeleton is developed and integrated with a brain-machine interface, and the effectiveness of the proposed exoskeleton system is finally supported by pilot animal tests.

Advisor: Tomizuka, Masayoshi
Wildfire Effects on the Ecohydrology of a Sierra Nevada Watershed

The mountain watersheds of the Sierra Nevada supply the majority of California's water, but this supply has always been highly variable. The 2012-2016 drought in California has demonstrated that this water supply is also highly vulnerable to increasing temperatures and/or reduced precipitation. Not only did the 2012-2016 drought reduce water supply for human use, but it also led to unprecedented forest mortality and fire damage. Unfortunately, the fire suppression strategy that was nearly uniformly applied to mountain forests during the 20$^{th}$ century may have exacerbated the effects of drought by increasing vegetation density and thus increasing evapotranspiration and precipitation interception. Could restoring fire regimes to their pre-European settlement condition increase water yield from these forested catchments? Such a policy would also have the potential to restore the ecological function of landscapes and reduce the risk of catastrophic fires (such as the 2013 Rim Fire) by reducing fuel loads./nThis dissertation studies the hydrological and landscape-level ecological effects of restoring a frequent, mixed severity fire regime to the Illilouette Creek Basin in Yosemite National Park. A combination of field measurements, historical data analysis, remote sensing, and modeling approaches are employed to strengthen the argument by providing multiple lines of evidence. There is limited data available for Illilouette Creek Basin during much of the four decades in which the new fire regime became established, inhibiting direct evaluation of the fire regime's effects. Nevertheless, a variety of different metrics and analyses indicate a number of important changes that can be attributed to the restored fire regime: increased landscape diversity (including reduced forest cover), increased soil moisture and streamflow (both according to measurements and hydrological modeling), and decreased drought stress (both according to observations and from hydrological modeling).

Advisor: Thompson, Sally E
The Good Neighbor Comes Home: The State, Mexicans and Mexican Americans, and Regional Consciousness in the US Southwest during World War II

“The Good Neighbor Comes Home: The State, Mexicans and Mexican Americans, and Regional Consciousness during World War II” is a study of how US foreign policy and World War II reshaped the relationship between local, state, and federal agencies and institutions and the Mexican and Mexican American population in the US Southwest. This study relies on archival research and materials from California, Arizona, New Mexico, Texas, and Washington, DC, to argue that this change in the relationship between the federal government and the Mexican and Mexican American population led to the emergence of a regional consciousness defined by the problems communities in California, New Mexico, and Texas shared in common across the US Southwest./nThe federal government first became interested in the well being of the Mexican and Mexican American population in the US Southwest because of its desire to maintain friendly relations with Latin America during the war emergency. The Good Neighbor Policy was the US foreign policy of non-intervention that promoted a sense of inter-Americanism based on a common American and democratic heritage in the western hemisphere. Both the Good Neighbor Policy and World War II provoked a collective response from local Mexican American leaders and sympathetic allies in the US Southwest: these figures turned inter-American and democratic wartime rhetoric to good account by insisting the federal government include a domestic program in its national diplomacy and security agendas to meet the population’s long-neglected needs. The federal government responded by creating the Spanish Speaking Minority Project within the domestic division of the Office of the Coordinator of Inter-American Affairs, the federal agency tasked with promoting the Good Neighbor Policy. An informal network of Mexican American leaders, federal bureaucrats, professionals, university administrators, and social scientists worked to bring federal funds into the US Southwest by defining a set of region-wide issues shared by the Mexican and Mexican American population, which contributed to the emergence of a regional consciousness, or an awareness of the problems held in common among Mexican and Mexican American communities in the US Southwest. “The Good Neighbor Comes Home” illustrates how the federal bureaucratic interest in the population emerged, how this interest both departed and continued from the federal government’s earlier interaction with the population, and how non-federal actors in California, New Mexico, and Texas relied upon and reinforced the population’s regional consciousness as they sought to improve Mexican and Mexican American conditions in the US Southwest.

Advisor: Klein, Kerwin L
Better, Faster, Stronger: Measuring and Transcending Your Physical Limits with Wearable Robots

This thesis introduces a kinematic and dynamic framework for creating a representative model of an individual. Building on results from geometric robotics, a method for formulating a geometric dynamic identification model is derived. This method is validated on a robotic arm, and tested on healthy subjects to determine the utility as a clinical tool./nThe proposed framework was used to augment the five-times sit-to-stand test. This is a clinical test designed to estimate an individual's stability by timing the total time to stand/sit five times. Using the proposed framework, a representative kinematic and dynamic model was obtained which outperformed conventional height/mass scaled models. This allows for rapid, quantitative measurements of an individual, with minimal retraining required for clinicians./nThese tools are then used to develop a prescriptive model for developing assistive devices. The recovered models can be used to formulate an optimisation to determine the actuator types and parameters to provide augmentation./nThis framework is then used to develop a novel system for human assistance. A prototype device is developed and tested. The prototype is lightweight, uses minimal energy, and can provide an augmentation of 82% for providing hammer curl assistance. The modelling framework is used to analyse the effect this assistance has on compensatory actions of the shoulder.

Advisor: Bajcsy, Ruzena
Optimizing Expectations: From Deep Reinforcement Learning to Stochastic Computation Graphs

This thesis is mostly focused on reinforcement learning, which is viewed as an optimization problem: maximize the expected total reward with respect to the parameters of the policy./nThe first part of the thesis is concerned with making policy gradient methods more sample-efficient and reliable, especially when used with expressive nonlinear function approximators such as neural networks. Chapter 3 considers how to ensure that policy updates lead to monotonic improvement, and how to optimally update a policy given a batch of sampled trajectories. After providing a theoretical analysis, we propose a practical method called trust region policy optimization (TRPO), which performs well on two challenging tasks: simulated robotic locomotion, and playing Atari games using screen images as input. Chapter 4 looks at improving sample complexity of policy gradient methods in a way that is complementary to TRPO: reducing the variance of policy gradient estimates using a state-value function. Using this method, we obtain state-of-the-art results for learning locomotion controllers for simulated 3D robots./nReinforcement learning can be viewed as a special case of optimizing an expectation, and similar optimization problems arise in other areas of machine learning; for example, in variational inference, and when using architectures that include mechanisms for memory and attention. Chapter 5 provides a unifying view of these problems, with a general calculus for obtaining gradient estimators of objectives that involve a mixture of sampled random variables and differentiable operations. This unifying view motivates applying algorithms from reinforcement learning to other prediction and probabilistic modeling problems.

Advisor: Abbeel, Pieter
The Social Origins of State Power in China

This dissertation investigates the origins of state power and political accountability. How do states exercise political control over their populations and implement policies that have clear winners and losers? Do democratic institutions in combination with a strong civil society strengthen political accountability? I examine these questions in the context of rural China, which combines limited local democracy and vibrant non-state groups such as kinship associations, temples, and neighborhood groups. Many argue that strong civil society institutions and local elections can curb the power of the state and hold government officials accountable. However, in this dissertation I argue that in China, strong civil society groups and village elections have expanded state power and helped officials confiscate wealth./nThe first part of the dissertation develops my theory of state power. Drawing on new data from rural China, I show that citizens distrust the ruling Chinese Communist Party (CCP) and believe that local party cadres do not represent their interests. On the other hand, the leaders of local civil society, especially the leaders of clans and neighborhood groups, enjoy high degrees of trust and moral authority. I argue that in this context, elected village councils and other participatory institutions are a mechanism for the state to identify local elites with significant informal authority within social groups. Once they join local political institutions, rent-sharing gives these social elites incentives to use their informal authority to help the CCP elicit compliance with potentially unpopular policies./nIn subsequent chapters, I draw on a mix of structured case studies and a unique national dataset to show how co-opting civil society elites has helped the CCP seize land from village collectives. These land expropriations have redistributed trillions of dollars of wealth from village collectives to the state and to local elites, and are one of the central political issues in contemporary China. I show how the leaders of clans, religious groups, and neighborhoods use their informal authority within their groups to elicit compliance with land confiscations. When these civil society leaders are included in village political institutions, land expropriations are more likely and the compensation for these expropriations is lower./nThese findings cast doubt on theories that hold that the main consequence of civil society institutions is to enhance political accountability. I argue that grassroots civil society institutions are encouraged and nurtured by the powerful because they reinforce the authority of local elites and because they help elites to control society. I also challenge theories that hold that democratic and participatory institutions curb the power of the state. Instead, these institutions can be used by authoritarian regimes to co-opt civil society leaders, who can help the state implement policies that redistribute wealth from the grassroots to elites.

Advisor: O'Brien, Kevin J
Contrived Conversions: The Master Narrative of Educational Uplift

Education in the United States has responded to the evolving demands of society. Historically, it has been tasked with supporting religion in colonial America, preparing citizens to support the republic, integrating new Americans into society, and cultivating an industrialized workforce. Throughout these movements in education, one enduring purpose for institutional schooling has been to adapt people to an extant social order. The master narrative of educational uplift has been a cornerstone of this project. Uplift prescribes a transformational trajectory by which anyone can achieve greater social and economic success through the pursuit of purportedly meritocratic education. It frames the world as fixed, and the ways to achieve success as scripted, as if education has always been the unequivocal pathway to accessing the privileges of subjectivity. Dominant in-groups sanction uplift as an equitable means for individuals to transition from object to social subject. However, uplift achieves the opposite of its ostensible objective: it does not move society towards greater egalitarianism, but rather reproduces structural inequalities and maintains exclusionary power relations. Instead of liberating individuals, it oppresses people by preventing them from recognizing and engaging with the world as a changeable reality they have the capacity to shape./nThis study, informed by critical pedagogy and critical race theory, examines how educational uplift operates in the modes of narrative, economic, and cultural conversions. Each mode is beholden to the uplift plot line, which requires that individuals change. In order to achieve liberating social transformation, oppressed peoples must develop critical consciousness and come together in solidary praxis, combining action with critical reflection. Mainstream educational uplift presents itself as a transhistorical emancipatory narrative that converts subpersons into full subjects, yet complete subjectivity is an unattainable ideal couched in normative middle-class whiteness. Closer analysis reveals that uplift is deeply ahistorical in its treatment of students as objects of conversion. A fully historicized narrative would acknowledge these individuals as makers of that narrative, capable of altering its terms themselves.

Advisor: McQuade, Donald
Women’s Clubs in California: Architecture and Organization, 1880-1940

This dissertation explores the role of architecture—specifically, clubhouses—in the construction and institutionalization of modern, organized womanhood in early twentieth-century California. Beginning in the 1870s women began gathering in groups across the country for self-education, self-discovery, and civic work. They called themselves “clubs,” a term borrowed from male culture indicating a new, more formal endeavor than existing women’s circles. By 1900 some one million women made up this vast, organized, and effective network. Through clubs women successfully fought for the right to vote, for juvenile courts, kindergartens, public libraries, drinking fountains, street lights, urban parks, improved sanitation, and other civic accomplishments we now consider essential public goods./nThe achievements of women’s clubs have become so seamlessly incorporated into our notion of American civic amenities that they appear inevitable, natural—almost innate. The purpose-built clubhouses that played host to these efforts are equally unrecognized. Beginning in the 1880s and 1890s, clubwomen abandoned their private parlors and rented rooms to build expensive new buildings for themselves to facilitate their social action and interaction. More than one thousand clubhouses were built nationwide between 1890 and 1940, and many still stand today. California, due to tremendous Progressive Era population growth and development and property laws allowing women to own real estate, led the nation in clubhouse construction./nTo raise funds to build, purchase a lot, hire an architect and contractor, and dictate and iterate upon a building program, as well as to operate, maintain, and often expand a clubhouse, was a massive, and massively symbolic undertaking. Initially the buildings centered on a single large, multipurpose assembly room used for meetings, performances, and lectures. As the institution matured many clubs built monumental structures that were part hotel, part restaurant, part YWCA, part country-club-in-the-city, and part social action headquarters. Through their clubhouses women gave material expression to the evolving meanings of womanhood, conveying their particular status as property and business owners, athletes, ambitious professionals, hardworking civil servants, or sophisticated urbanites, in turn. Clubhouses are an architectural type representative of women’s influence in turn of the century cities, and they represent both the ambitious scope and the shortcomings of organized womanhood.

Advisor: Shanken, Andrew
Ordering People and Nature through Food Safety Governance

We are constantly reminded that eating fresh fruits and vegetables is healthy for us. But in the face of repeated outbreaks of foodborne illness linked to fresh produce, whether these foods are safe for us has become an entirely different, and difficult to answer, question. In the name of food safety, both government and industry leaders are adopting far-reaching policies intended to prevent human pathogens from contaminating crops at the farm level, but these policies meet friction on the ground. Through a case study of the California leafy greens industry, this dissertation examines the web of market, legal, technological, and cultural forces that shape how food safety policy is crafted and put into practice in fields./nControlling dangerous pathogens and protecting public health are not the only goals served by expanding food safety regulation—food safety also serves to discipline and order people and nature for other purposes. Private firms use the mechanisms of food safety governance to shift blame and liability for foodborne pathogens to other sectors or competitors and to secure a higher market share for themselves. Food safety experts, capitalizing on the lack of available science upon which to base standards, carve out for themselves a monopoly in setting and interpreting food safety standards. And government agents wield their expanded policing powers primarily to make examples of a few bad actors in order to shore up public confidence in the food system and the government’s ability to protect its citizens, but fail to address underlying structural causes./nZealous fixation with driving risk of microbial contamination toward an always out-of-reach “zero” draws attention away from the systemic risks inherent in the food system status quo and stifles alternative pathways for growing and distributing food, raising thorny complications for diversifying—ecologically, economically, or culturally—our country’s food provisioning system. The narrow scope of existing food safety policy must be broadened and developed holistically with other societal goals if the future of US agriculture is to be sustainable and resilient in the long term.

Advisor: Iles, Alastair T
Continuous and Discrete Dynamics For Online Learning and Convex Optimization

Online learning and convex optimization algorithms have become essential tools for solving problems in modern machine learning, statistics and engineering. Many algorithms for online learning and convex optimization can be interpreted as a discretization of a continuous time process, and studying the continuous time dynamics offers many advantages: the analysis is often simpler and more elegant in continuous time, it provides insights and leads to new interpretations of the discrete process, and streamlines the design of new algorithms, obtained by deriving the dynamics in continuous time, then discretizing. In this thesis, we apply this paradigm to two problems: the study of decision dynamics for online learning in games, and the design and analysis of accelerated methods for convex optimization./nIn the first part of the thesis, we study online learning dynamics for a class of games called non-atomic convex potential games, which are used for example to model congestion in transportation and communication networks. We make a connection between the discrete Hedge algorithm for online learning, and an ODE on the simplex, known as the replicator dynamics. We study the asymptotic properties of the ODE, then by discretizing the ODE and using results from stochastic approximation theory, we derive a new class of online learning algorithms with asymptotic convergence guarantees. We further give a more refined analysis of these dynamics and their convergence rates. Then, using the Hedge algorithm as a model of decision dynamics, we pose and study two related problems: the problem of estimating the learning rates of the Hedge algorithm given observations on its sequence of decisions, and the problem of optimal control under Hedge dynamics./nIn the second part, we study first-order accelerated dynamics for constrained convex optimization. We develop a method to design an ODE for the problem using an inverse Lyapunov argument: we start from an energy function that encodes the constraints of the problem and the desired convergence rate, then design an ODE tailored to that energy function. Then, by carefully discretizing the ODE, we obtain a family of accelerated algorithms with optimal rate of convergence. This results in a unified framework to derive and analyze most known first-order methods, from gradient descent and mirror descent to their accelerated versions. We give different interpretations of the ODE, inspired from physics and statistics. In particular, we give an averaging interpretation of accelerated dynamics, and derive simple sufficient conditions on the averaging scheme to guarantee a given rate of convergence. We also develop an adaptive averaging heuristic that empirically speeds up the convergence, and in many cases performs significantly better than popular heuristics such as restarting.

Advisor: Bayen, Alex M
Bartlett, Peter L