VictorJuiz/thesis huggingface dataset:
Algorithms for exploring and controlling procedural models [electronic resource]

Enabling ordinary people to create high-quality 3D models is a long-standing problem in computer graphics. While much recent work has focused on the development of more sophisticated systems for geometric modeling, procedural techniques provide powerful means for generating complex geometric structures such as those commonly found in botany and architecture. Procedural representations are also notoriously difficult to interact with and control. In this thesis, we contribute two algorithms for making procedural modeling more accessible. We first draw from the literature on design and human cognition to better understand the design processes of novice and casual modelers, whose goals and motivations are often distinct from those of professional artists. We use this understanding to propose a collaborative system for exploratory modeling, in which users navigate a complex "design space" of parametric models using a simple, two-dimensional map interface. As users save models for their own personal use, their actions are communicated to a shared repository to improve the performance of the method, resulting in a self-reinforcing system that becomes easier to use as more people participate. Next, we present a method for bringing artistic control to grammar-based procedural models. Given a grammar and a high-level specification of a desired model, our algorithm computes a production from the grammar that conforms to the specification. This production is generated by optimizing over the language of the grammar using trans-dimensional Markov chain Monte Carlo inference. No interaction with the grammar itself is required, and the input specification can take many forms, such as a sketch, a volumetric shape, or an analytical objective.

Advisor: Koltun Vladlen
Goodman Noah (Noah D.) advisor. Thesis advisor
Hanrahan P. M. (Patrick Matthew) advisor. Thesis advisor
America's teachers, do management practices in public schools provide incentives for quality teaching? [electronic resource]

Do management practices in America's public schools provide incentives for quality teaching? This dissertation argues that (i) current pay practices in teaching do not provide incentives for the most able individuals to become teachers and (ii) the changed management practices that accompanied the introduction of accountability programs improved the quality of teaching in poorly performing schools. Using data from Florida, Illinois, North Carolina, Texas, Virginia, Pennsylvania, and Wisconsin, the structure of pay in public schools during 1993 through 2003 is compared to the structure of pay in other occupations requiring a college degree. Those who leave teaching during this period earn much less after leaving, even after several years. This suggests that pay practices in teaching have not been successful in attracting the most able individuals to teaching. (Otherwise, at least some individuals would exit teaching for higher pay when outside opportunities improved, as they did in the late 1990s.) The management practices that accompanied the introduction of accountability likely improved the quality of teaching in poorly performing schools through two channels: (i) existing teachers made more effort, and (ii) many of the worst teachers left teaching. Moonlighting (working a second job) is used as an inverse proxy for effort because a full-time worker is likely exerting only limited effort if she is moonlighting. Teachers in public schools exposed to performance pressure from a state accountability system were much less likely to moonlight and much more likely to leave teaching. Those who left teaching did not fare well in the broader labor market; they earned less than they did as teachers, even after several years. Data from three states that implemented demanding accountability systems in the 1990s (Florida, Illinois, and North Carolina) are used. Taken together, these results suggest that accountability did help to improve the quality of teaching in poorly performing schools.

Advisor: Shaw Kathryn primary advisor. Thesis advisor
Hoxby Caroline Minter advisor. Thesis advisor
Lazear Edward P. advisor. Thesis advisor
America's teachers, do management practices in public schools provide incentives for quality teaching? [electronic resource]

Do management practices in America's public schools provide incentives for quality teaching? This dissertation argues that (i) current pay practices in teaching do not provide incentives for the most able individuals to become teachers and (ii) the changed management practices that accompanied the introduction of accountability programs improved the quality of teaching in poorly performing schools. Using data from Florida, Illinois, North Carolina, Texas, Virginia, Pennsylvania, and Wisconsin, the structure of pay in public schools during 1993 through 2003 is compared to the structure of pay in other occupations requiring a college degree. Those who leave teaching during this period earn much less after leaving, even after several years. This suggests that pay practices in teaching have not been successful in attracting the most able individuals to teaching. (Otherwise, at least some individuals would exit teaching for higher pay when outside opportunities improved, as they did in the late 1990s.) The management practices that accompanied the introduction of accountability likely improved the quality of teaching in poorly performing schools through two channels: (i) existing teachers made more effort, and (ii) many of the worst teachers left teaching. Moonlighting (working a second job) is used as an inverse proxy for effort because a full-time worker is likely exerting only limited effort if she is moonlighting. Teachers in public schools exposed to performance pressure from a state accountability system were much less likely to moonlight and much more likely to leave teaching. Those who left teaching did not fare well in the broader labor market; they earned less than they did as teachers, even after several years. Data from three states that implemented demanding accountability systems in the 1990s (Florida, Illinois, and North Carolina) are used. Taken together, these results suggest that accountability did help to improve the quality of teaching in poorly performing schools.

Keywords: Business.
Advisor: Shaw Kathryn primary advisor. Thesis advisor
Hoxby Caroline Minter advisor. Thesis advisor
Lazear Edward P. advisor. Thesis advisor
An Analysis of the Credit Union for Migrant Workers in Thailand

Along the Thai-Burmese border region of the Sangkhlaburi District, Kanchanaburi province, Thailand, there reside displaced ethnic communities who migrated from Burma. These people have been deprived of access to commercial banks or any other formal financial services because they do not carry Thai identification cards. This form of financial exclusion acts as a barrier to development for this local community. In order to analyze the effectiveness of one institution, the Pattanarak Credit Union (PCU), that addresses the financial needs of this community in terms of meeting legitimate financial needs of the migrant workers, I test if the PCU charges competitive rates and provides much-needed loans to the members of the group. This paper proposes a financial model to study the effectiveness of the PCU and analyzes the savings and borrowing mechanisms of its microcredit program. My honors thesis shows that the PCU’s mechanisms have been effective in keeping the default rate at zero and withdrawal rate low. This study also finds that the interest rates charged on borrowers should be raised to maximize dividends distributed back to members of the credit union, which is in keeping with the PCU’s social mission.

Keywords:  Department of Economics
Stanford Department of Economics
microfinance
interest rate
microloan
migrant workers
financial exclusion
Thesis
Advisor: Hope Nicholas C.
Analysis and synthesis of three-dimensional illumination using partial coherence [electronic resource]

There exists many devices that generate three-dimensional illumination patterns. Analysis of the capabilities of three major device families using measures of partial coherence reveals specific illumination patterns that cannot be generated by each device family. Ray-based devices cannot achieve patterns with high resolution, coherent holographic devices cannot achieve certain intensity patterns, even in the two-dimensional case, and volumetric devices cannot simulate occlusions and suffer from out-of-focus blur. Synthesis of more versatile illumination patterns is proposed by computing the mutual intensity representation of a desired partially coherent beam from application specifications and then generating the beam using time-multiplexing methods based on coherent modes. The mutual intensity can be computed directly from a simple scene description, or it can be computed through a novel algorithm using nonlinear conjugate gradients from a desired three-dimensional intensity volume. Equivalent coherent mode decomposition representations for the same mutual intensity will be considered in terms of optimality in efficiency. For cases when the computed mutual intensity is fairly incoherent, a new "quasi-Schell" mode decomposition is proposed to reduce the number of patterns needed at the SLM by introducing partially coherent sources. Use of arbitrary partially coherent beams for three-dimensional illumination enables the versatile generation of light patterns not possible with current devices and is a promising new field for exploration.

Keywords: Electrical Engineering
Advisor: Levoy Marc primary advisor. Thesis advisor
Barbastathis George advisor. Thesis advisor
Horowitz Mark (Mark Alan) advisor. Thesis advisor
Analytical goal-driven learning of procedural knowledge by observation [electronic resource]

Knowledge-based approaches to planning and control offer benefits over classical techniques in applications that involve large yet structured state spaces. However, knowledge bases are time consuming and costly to construct. In this dissertation I introduce a framework for analytical learning that enables the agent to acquire generalizable, domain-specific procedural knowledge in the form of goal-indexed hierarchical task networks by observing a small number of successful demonstrations of goal-driven tasks. I discuss how, in contrast with most algorithms for learning by observation, my approach can learn from unannotated input demonstrations by automatically inferring the purpose of each solution step using the background knowledge about the domain. I discuss the role of hierarchical structure, distributed applicability conditions, and goals in the generalizability of the acquired knowledge. I also introduce an approach for adaptively determining the structure of the acquired knowledge that strikes a balance between generality and operationality, and for making the algorithm robust to changes in the structure of background knowledge. This involves resolving interdependencies among goals using temporal information. I present experimental studies on a number of domains which demonstrate that the quality of acquired knowledge is comparable to handcrafted content in terms of both coverage and complexity. In closing, I review related work and directions for future research.

Keywords: Electrical Engineering
Advisor: Das Amar K. (Amar Kumar) primary advisor. Thesis advisor
Widrow Bernard
Langley Pat advisor. Thesis advisor
Anatomy of the australopithecus scapula and evolution of the human shoulder [electronic resource] : insights from a new fossil specimen, KSD-VP-1/1g

Striding bipedalism is a mode of locomotion that defines our lineage. Bipedality freed the hands, arms and shoulders from the mechanical constraints of locomotion, an evolutionary innovation that has had an obvious impact on our species' fitness. As I will discuss in this dissertation, the shoulder blade (scapula) is shaped to optimize use of the upper limb in certain positions. Our closest living relatives (chimpanzees and gorillas) possess adaptations that likely increase efficiency in overhead use of the arms, as in forearm suspension or vertical climbing. The modern human shoulder, on the other hand, lacks such adaptations. This difference may reflect an evolutionary change in shape that occurred as our ancestors transitioned to a terrestrial way of life and became increasingly dexterous, eventually losing ancestral adaptations. On the other hand, recent discoveries suggest our lineage may have never possessed adaptations to suspension. Fossils from the shoulder of our early human ancestors are scarce. A recently discovered partial skeleton from Woranso-Mille (Afar Depression, Ethiopia), KSD-VP-1/1, preserves the oldest and most complete scapula of an adult Australopithecus afarensis individual. The intended contribution of this dissertation is to provide a comparative description of the new scapula (KSD-VP-1/1g) and to detail its implications for our understanding of anatomy and adaptation in the Australopithecus shoulder, and the evolutionary history of the modern human shoulder more generally.

Keywords: Biology.
Advisor: Klein Richard primary advisor. Thesis advisor
Hadly Elizabeth Anne
Haile-Selassie Yohannes
Anomaly detection as creative insight [electronic resource]

The costs of undetected design problems are huge, especially for automobiles, and similar expensive, complex products manufactured in high numbers. If design issues are not discovered before production begins, the cost and impact of design changes increase dramatically. When design problems remain hidden all the way through manufacture, substandard products may reach the public, with severe consequences. This research began with a qualitative field study using grounded theory and ethnography to examine the activities of geographically distributed automotive design workers. The early detection of design issues was predicted to produce higher quality products and improved productivity. Research questions were chosen: What is an anomaly? What is the anomaly detection process? Anomaly detection was explored with an experiment in which test subjects (N = 65) reviewed images for anomalies. The primary finding was that anomaly detection is a significant human design activity. Specific definitions for anomalies and the anomaly detection process were developed. The steps in the anomaly detection process were identified. The differences between errors and anomalies were researched and described. An anomaly coding scheme was created. Anomaly detection was found to be learnable and teachable. Opportunities for the use of anomaly detection in design were revealed. It was found that anomalies are creative insights. The role of ambiguity in design representations was revealed. The study found a need for representations to be unambiguous and easily understood by users. The role of poor quality representations that prevent observers from detecting structural and functional anomalies was clarified.

Keywords: Mechanical Engineering
Advisor: Leifer Larry J. primary advisor. Thesis advisor
Beach David W.
Steinert Ralf advisor. Thesis advisor
Tversky Barbara advisor. Thesis advisor
Atomic force microscopy methods for characterizing drug delivery agents [electronic resource]

Recent successes in the pharmaceutical industry have yielded a variety of new drugs based on proteins and nucleic acids. While these drugs are very promising, they are only effective once they are inside cells. Unfortunately, transporting drugs into cells tends to be challenging because cell membranes provide a protective barrier. However, there is hope for these drugs since researchers have identified many drug delivery agents that can shuttle drugs past this barrier. Cell penetrating peptides (CPPs) are particularly promising delivery agents due to their low toxicity and ability to deliver a wide number of therapeutic agents. However there are challenges to using CPPs, because their delivery mechanisms cannot yet be controlled. Engineering new CPPs that use specific, known translocation mechanisms would be a key achievement that could increase delivery efficiency and prevent unwanted side effects. Accomplishing this goal requires new experimental methods for determining the factors that control a CPP's translocation mechanisms. In this thesis I present new atomic force microscopy (AFM) methods for studying CPPs and other cell membrane active species. I first present a theoretical model that shows how results from AFM can indicate whether CPPs change the energy barrier to bilayer penetration. I then describe new experimental AFM methods we developed for examining CPP transduction mechanisms.

Keywords: Materials Science and Engineering
Advisor: Melosh Nicholas A. primary advisor. Thesis advisor
Dauskardt R. H. (Reinhold H.) advisor. Thesis advisor
Heilshorn Sarah advisor. Thesis advisor
Automatic laser calibration, mapping, and localization for autonomous vehicles [electronic resource]

This dissertation presents several related algorithms that enable important capabilities for self-driving vehicles. Using a rotating multi-beam laser rangefinder to sense the world, our vehicle scans millions of 3D points every second. Calibrating these sensors plays a crucial role in accurate perception, but manual calibration is unreasonably tedious, and generally inaccurate. As an alternative, we present an unsupervised algorithm for automatically calibrating both the intrinsics and extrinsics of the laser unit from only seconds of driving in an arbitrary and unknown environment. We show that the results are not only vastly easier to obtain than traditional calibration techniques, they are also more accurate. A second key challenge in autonomous navigation is reliable localization in the face of uncertainty. Using our calibrated sensors, we obtain high resolution infrared reflectivity readings of the world. From these, we build large-scale self-consistent probabilistic laser maps of urban scenes, and show that we can reliably localize a vehicle against these maps to within centimeters, even in dynamic environments, by fusing noisy GPS and IMU readings with the laser in realtime. We also present a localization algorithm that was used in the DARPA Urban Challenge, which operated without a prerecorded laser map, and allowed our vehicle to complete the entire six-hour course without a single localization failure. Finally, we present a collection of algorithms for the mapping and detection of traffic lights in realtime. These methods use a combination of computer-vision techniques and probabilistic approaches to incorporating uncertainty in order to allow our vehicle to reliably ascertain the state of traffic-light-controlled intersections.

Advisor: Thrun Sebastian
Koller Daphne advisor. Thesis advisor
Levoy Marc advisor. Thesis advisor
Autonomous Sign Reading for Semantic Mapping on the Stanford AI Robot

This thesis considers the problem of automatically collecting semantic labels during robotic mapping by extending the mapping system to include text detection and recognition modules.In particular, it describes a system by which a SLAM-generated map of an office environment can be annotated with text labels such as room numbers and the names of office occupants. These labels are acquired automatically from signs posted on walls throughout a building using a feed-forward system that collects a set of building images; uses a trained classifier to detect candidate text regions on those images; runs optical character recognition on those regions to extract the textual content; and post-processes the text string set with alignment information before placing each string at its original location on the map. Such a system faces difficulties using current text recognition techniques, as standard approaches to optical character recognition fail when faced with text from natural images as opposed to document text. Despite these difficulties, our system provides a series of additions to the typical mapping pipeline which provide practically useful results. In fact, our text detection and recognition system, combined with other ingredients, allow the robot to generate an annotated map from which it can recognize named locations specified by a user 84% of the time.

Keywords: Computer Science.
Robots > Control systems
Autonomous robots
Semantic networks > Information theory
Thesis
Advisor: Ng Andrew Y.
Axe, an automated formal equivalence checking tool for programs [electronic resource]

This dissertation describes Axe, an automated formal verification tool for proving equivalence of programs. Axe has been used to verify real-world Java implementations of cryptographic operations, including block ciphers, stream ciphers, and cryptographic hash functions. Axe proves the bit-for-bit equivalence of the outputs of two programs, one of which may be a formal, mathematical specification. To do so, Axe relies on a novel combination of techniques from combinational equivalence checking and inductive theorem proving. First, the loops in some programs can be completely unrolled, creating large loop-free terms. Axe proves the equivalence of such terms using a phased approach, including aggressive word-level simplifications, bit-blasting, test-case-based identification of internal equivalences, and ``sweeping and merging.'' For loops that cannot be unrolled, Axe uses execution traces to detect loop properties, including loop invariants for single loops and connection relationships between corresponding loops. Axe proves such properties inductively. In many cases, synchronizing transformations must be performed to align the loop structures of the programs being compared; Axe can perform and verify a variety of these transformations.

Advisor: Dill David L. primary advisor. Thesis advisor
Engler Dawson R. advisor. Thesis advisor
Mitchell John C. advisor. Thesis advisor
Bahamian students' experiences with mathematics in American universities and colleges [electronic resource]

This longitudinal, qualitative, multi-case study examines the mathematical experiences of three Bahamian students pursuing science degrees in American universities and its relationship to their previous mathematical experiences in their Bahamian high schools. Drawing on cultural psychology and sociocultural theories of learning, this study found that the relationship between the academic preparedness of the participants on their experiences with collegiate mathematics is not limited to subject content only. The lessons learnt from the implied curriculum also play a role in their experiences with collegiate mathematics. Of the three participants, two have had to learn/develop techniques for studying because they had not been sufficiently challenged in their previous environments to do so. Each of the cases also highlights some powerful constructs needed for success in mathematics and at least two emphasize making connections between concepts, procedures, manipulatives/tools and multiple approaches when solving problems. This study contributes to an emerging area of research on student persistence in college-level mathematics courses as well as to the ongoing discussions in mathematics education regarding the role/importance of conceptual understanding and how to promote it. The study makes visible some of the ways in which students' post-secondary experiences with mathematics are shaped by their perception of their mathematical preparation, thus providing a basis for discussions of possible curricular change in the Bahamas. It also suggests that issues such as confidence and school/teacher expectations of students may play a role in the development of conceptual understanding.

Keywords: Education.
Advisor: Boaler Jo
Murata Aki primary advisor. Thesis advisor
Nasir Na'ilah Suad