VictorJuiz/thesis huggingface dataset:
GPU parallel processing for fast robotic perception [electronic resource]
Keywords: Electrical Engineering

In this thesis we detail how we built GPU-executed versions of two modern computer vision applications: one a visual servoing algorithm (to control a robotic arm with visual feedback) and the other a sliding-window object detector (to recognize instances of an object class in an image). Starting from slow reference solutions for both algorithms, our goal was to achieve as close to real-time speeds as possible so that these state-of-the-art algorithms could be incorporated onto a mobile robotics platform. We used general-purpose computing on graphics processing units (GPGPU) to accelerate the programs as this strategy has already been used to achieve large speed-ups (of factors of ten to a hundred) on other complex problems. We furthermore developed our applications with CUDA (Compute Unified Device Architecture), which is a programming interface developed by NVIDIA Corporation to perform GPGPU on their graphics hardware. In this thesis we first give a detailed introduction to CUDA, and then we describe in-depth how we built the GPGPU versions of the two computer vision algorithms. In both cases our goals of real-time execution were achieved, seeing end-to-end speed-ups of around fiftyfold.
Has the Crisis Passed? Assessing the Effectiveness of the Term Auction Facility
Keywords:  Department of Economics
Stanford Department of Economics
federal funds rate
inter-bank loans
Federal Reserve
Term Auction Facility
liquidity risk premium
credit risk premium
term risk premium
Thesis

A key feature of the ongoing financial crisis has been the dramatic and persistent increase in the spreads between the federal funds rate and longer term inter-bank loans. The Federal Reserve has tried to combat the rise in these spreads by injecting liquidity into the market through the creation of measures such as the Term Auction Facility (TAF). The effectiveness of these measures depends on the causes of increased spreads. Is it the liquidity risk premium that is driving inter-bank rates higher? Or instead, are rates being pushed higher by elevated credit risk premiums resulting from the increased risk of default by banks? Using a no-arbitrage model for defaultable bond pricing, I decompose the inter-bank rate into its liquidity, credit and term risk premiums. I then estimate the effectiveness of the TAF in reducing liquidity premiums and find that it had a moderate effect on spreads, indicating that the liquidity risk premium has been a factor in the inter-bank market. I end with a discussion of the implications this result has on future Fed policy towards lowering spreads in the inter-bank market.
High-fidelity, broadband amplification and filtering for spaceborne instrumentation [electronic resource]
Keywords: Electrical Engineering

This work presents the first fully integrated analog front-end for satellite-based, wideband plasma wave receivers. To enable the next generation of scientific instruments for comprehensive study of wave particle interactions in the Van Allen radiation belts, it comprises: a programmable-gain, low-noise amplifier for electric-field measurements from 100 Hz to 4 MHz that achieves 90-dB SFDR while consuming less than 2 mW; and, a programmable-bandwidth, sixth-order, anti-aliasing filter predicated on a novel, widely tunable transconductor that offers better than 90-dB odd-harmonic suppression and power-efficient field trimming. Notable contributions of this research include design techniques which assure that both elements not only demonstrate high linearity throughout their wide programming ranges but also maintain their performance well beyond a total absorbed dose of 100 krad(Si) with no latchup for LETs of ~100 MeV-cm^2/mg, despite the intrinsic radiation susceptibilities of the commercial manufacturing process in which they are fabricated. To validate these techniques, extensive baseline, radiation, and burn-in tests have been performed; the corresponding experimental procedures and measured results are also tendered.
High-resolution diffusion MRI of targeted regions [electronic resource]
Keywords: Electrical Engineering

Diffusion magnetic resonance imaging (MRI) is an MRI method that provides information about random microscopic motion of water molecules in biological tissues. In addition to offering a higher sensitivity for the diagnosis of white matter diseases such as stroke and multiple sclerosis, and producing connectivity maps of the brain, it is a promising prognostic tool in the assessment and treatment response monitoring of cancer in the body. While high in-plane resolution is desirable for all diffusion MRI applications, it is particularly essential for imaging of small structures. Unfortunately, the performance of diffusion MRI techniques is often hindered by a variety of factors including susceptibility variations, field inhomogeneities and bulk physiologic motion. This thesis presents a reduced field-of-view (FOV) single-shot echo-planar imaging (ss-EPI) method to address these problems and enable high-resolution diffusion MRI of targeted regions. The proposed method utilizes a two-dimensional (2D) echo-planar radio-frequency (RF) excitation pulse to achieve a sharp reduced-FOV profile, while still allowing contiguous multi-slice imaging and suppressing the fat signal. Extensive clinical evaluation of the technique demonstrated that sub-mm diffusion-weighted imaging (DWI) on human spinal cords is feasible with minimal artifacts. High-resolution fiber tractography of the spinal cord successfully visualized the connectivity between the cord and the medulla oblongata, delineating internal structures such as gray/white matter. In vivo DWI of the larynx, breast and prostate validated the effectiveness of this technique in providing detailed depiction of the morphology outside the central nervous system. When the exponential diffusion attenuation is combined with high spatial resolution, DWI may suffer from poor signal-to-noise ratio (SNR). The last part of this thesis presents an optimization strategy for the DWI parameters as a function of the imaging SNR. Specifically, the optimum b-value is shown to be a monotonically increasing function of the imaging SNR, with a convergence asymptote identical to the previously proposed values in literature. The effects of T2 relaxation are also incorporated for a more accurate optimization. In vitro and in vivo experiments demonstrated reduced error in ADC estimations and improved SNR in the diffusion-weighted images with the proposed technique.
High-voltage-tolerant I/O design for USB 2.0-compliant systems [electronic resource]
Keywords: Electrical Engineering

The design of I/O user interfaces continues to grow in importance as the "digital revolution" gathers momentum. In such I/O interfaces, one frequently occurring challenge is the need to accommodate over-voltage conditions, in which the I/O signals range beyond the nominal voltage ratings of the I/O supplies. This vulnerability results from the fact that most I/O ports are exposed to users during operation, resulting in relatively uncontrolled terminations or even user abuse. This problem is exacerbated by a mismatch in the scaling rates of CMOS processes and I/O standards, forcing transistors with reduced voltage tolerance to implement interfaces with higher I/O voltages. The design problems associated with over-voltage conditions are important because it directly affects the lifetime of the product. In this work, we identify design challenges in the presence of over-voltage conditions and derive design guidelines for end-user systems taking a USB 2.0-compliant I/O as a test vehicle. We further demonstrate over-voltage-protected I/O circuits and high-robustness on-chip ESD protection in a 90-nm CMOS process. Our I/O circuit provides over-voltage protection against stress ranging from -1 to 5.25 V with continuous monitoring and compatibility with power-down mode. To enable this protection using today's CMOS technology, an additional bias voltage is used. Also, a dedicated over-voltage detection circuit with no static power consumption centrally controls protection paths to realize continuous monitoring. The protection concept of the I/O circuits integrated in the USB transmitters and receivers has been demonstrated with and without power present. Our ESD design realizes an extremely robust on-chip ESD protection concept, achieving an ESD robustness of 5 A TLP current, equivalent to an 8 kV HBM level, while fulfilling the over-voltage and high-speed requirements of the USB 2.0 system. The proposed architectures, employing SCR devices with triggering circuits implemented using a diode-string or a PMOS device, exhibit high ESD robustness, compatibility with over-voltage conditions, and suppressed interaction between the ESD circuit and regular I/O signaling in any state of system power.
How Long Will You Live: Using Life Insurance Prices to Infer Market Expectations About Improvements in Lifespan
Keywords:  Department of Economics
Stanford Department of Economics
market expectation
life expectancy
Health and Retirement Study
Thesis

Life insurance markets are immensely popular in the United States, helping families to smooth consumption in the event of the death of a primary earner. Insurance firms price these products to reflect the life expectancy of the purchaser. However, life expectancies change over time and steadily lengthened throughout the twentieth century as a result of technological progress in fields like nutrition, sanitation, and healthcare. Given this upward trend in lifespan, I question whether expectations of future increases in life expectancy influence life insurance prices. I build off of research by Alpert, Bhattacharya, and Sood (2004) to construct a theoretical model for insurance prices that excludes any potential expectations effects. By comparing this model to actual life insurance prices from the 1994 Health and Retirement Study (HRS), I observe whether expectations of improvements in medical technology drive life insurance prices downward. After making this comparison, I find no overwhelming evidence that market expectations had a substantial effect on the prices of life insurance products held by HRS respondents.
A hybrid model for timbre perception [electronic resource] : quantitative representations of sound color and density
Keywords: Music

Timbre, or the quality of sound, is a fundamental attribute of sound. It is important in differentiating between musical sounds, speech utterances, everyday sounds in our environment, and novel synthetic sounds. This dissertation presents quantitative and perceptually valid metrics for sound color and density, where sound color denotes an instantaneous (or atemporal) spectral energy distribution, and density denotes the fine-scale temporal attribute of sound. In support of the proposed metrics, a series of psychoacoustic experiments was performed. The quantitative relationship between the spectral envelope and subjective perception of complex tones was investigated using Mel-frequency cepstral coefficients (MFCC) as a representation of sound color. The experiments consistently showed that the MFCC model provides a linear and orthogonal coordinate space for human perception of sound color. The statistics for all twelve MFCC were similar at average correlation (R-squared or R2) of 85%, suggesting that each MFCC contains perceptually important information. The regression coefficients did suggest, however, the lower-order Mel-cepstrum coefficients may be more important in human perception than the higher-order coefficients. The quantitative relationship between the fine-scale temporal attribute and subjective perception of noise-like stimuli was investigated using normalized echo density (NED). Regardless of the sound color of the noise-like stimuli, the absolute difference in NED showed a strong correlation to the perceived dissimilarity with R2 of 93% on average. The other experiments showed that NED could represent the density perception in a consistent and robust manner across bandwidths--static noise-like stimuli having similar NED values were perceived as similar regardless of their bandwidth. Overall, with these experiments, NED showed a strong linear correlation to human perception of density, along with robustness in estimating the perceived density across various bandwidths, demonstrating that NED is a promising model for density perception. The elusive nature of timbre description has been a barrier to music analysis, speech research, and psychoacoustics. It is hoped that the metrics presented in this dissertation will form the basis of a quantitative model of timbre perception.
Image reconstruction for high-resolution PET [electronic resource] : GPU-accelerated strategies for improving image quality and accuracy
Keywords: Electrical Engineering

Molecular imaging can interrogate subtle molecular disease signatures non-invasively in living subjects. Positron emission tomography (PET), one particular molecular imaging modality, is able to sense molecular signals deep within tissue. Although PET is well suited for imaging signals associated with cancerous lesions in humans, it is still unable to resolve very small (< 2 mm) structures. Improving the spatial resolution of PET is an active area of research driven by many potential applications. However, the new generation of high-resolution PET systems raise new challenges for image reconstruction. In this dissertation, several strategies and algorithms are proposed to enable accurate and practical image reconstruction for high-resolution PET. Reconstruction is performed directly from the list-mode data via maximum-likelihood estimation. A shift-varying model of the imaging process is incorporated in the reconstruction. For fast reconstruction, the calculations are implemented using highly-parallel graphics processing units (GPU). A Bayesian sequence reconstruction algorithm is also used to position the annihilation photons that deposit energy in multiple detection elements. We show that the reconstruction provides near-uniform spatial resolution throughout the field-of-view, enhanced trade-off between noise and contrast, and better image quantitative accuracy. Furthermore, thanks to the computing power of graphics hardware, reconstruction times are practical for clinical applications.
Implementable schemes for lossy compression [electronic resource]
Keywords: Electrical Engineering

In spite of all the achievements of information theory in the last 60 years, some of its basic questions, specially in the area of source coding, have not found satisfying solutions yet. Finding an implementable scheme for universal lossy compression, that is part of the focus of this work, serves as a good example. Unlike universal lossless compression, for which there are several well-known practical algorithms, e.g., the famous work published in 1978 by Lempel and Ziv which its modified versions are used even today, for the universal lossy compression, the situation is not so positive. We propose two new paradigms for universal lossy compression. One of them takes advantage of Markov chain Monte Carlo combined with simulated annealing, and the other one has Viterbi algorithm at its core. Both algorithms try to approximate the solution of a universal exhaustive search scheme which has enormous computational complexity. The performance of both algorithms, theoretically, gets as close as desired to the solution of the original algorithm, but we do not have a bound on the required computations versus the desired precision. However, we show through our simulations on memoryless binary, and first-order binary Markov sources that the performance of both algorithms gets close to the rate-distortion curve for a number of computations linear in the block size. We also consider the Wyner-Ziv (WZ) problem of lossy compression where the decompressor observes a noisy version of the source, whose statistics are unknown. A new family of WZ coding algorithms is proposed and their universal optimality is proven. Compression consists of sliding-window processing followed by Lempel-Ziv (LZ) compression, while the decompressor is based on a modification of the discrete universal denoiser DUDE algorithm to take advantage of side information. The new algorithms not only universally attain the fundamental limits, but also suggest a paradigm for practical WZ coding. The effectiveness of our approach is illustrated with experiments on binary images, and English text using a low complexity algorithm motivated by our class of universally optimal WZ codes. Finally, we investigate the problem of Multiple Description MD coding of discrete ergodic processes. We introduce the notion of MD stationary coding, and characterize its relationship to the conventional block MD coding. In stationary coding, in addition to the two rate constraints normally considered in the MD problem, we consider another rate constraint which reflects the conditional entropy of the process generated by the third decoder given the reconstructions of the two other decoders. The relationship that we establish between stationary and block MD coding enables us to devise a universal algorithm for MD coding of discrete ergodic sources, based on simulated annealing ideas that were recently proven useful for the standard rate distortion problem.
Influence of magnetic field on dielectric susceptibility of amorphous solids at ultra low temperature [electronic resource]
Keywords: Physics.

The dielectric response of some amorphous solids below 100 mK is known to be sensitive to an applied magnetic field. This work presents new experimental data on the behavior of BK7, Aluminum-Barium-Silicate, Suprasil, Corning® microscope cover glass and Mylar® film (amorphous Polyethylene Terephthalate) samples in the temperature range from 2 mK to 100 mK in presence of a slowly varying magnetic field. We studied the dielectric constant by means of continuous wave AC capacitance measurements at 1 kHz. We observed hysteresis in the dielectric response to a magnetic field varying in a saw-like pattern with field strengths up to 2 milliTesla. The pattern of the response differs depending on the glass composition. The results presented in this work are consistent with previously made observations that nuclear spins greater than 1/2 play a crucial role in the observed magnetic field dependence.
Insights into the Evolution of a Coastal Barrier System Using Ground-Penetrating Radar: Bay of Plenty, New Zealand
Keywords:  Department of Geological and Environmental Sciences
School of Earth Energy &amp; Environmental Sciences
coastlines
New Zealand
Thesis

The internal structure of a prograding barrier ridge system within the coastline of the Bay of Plenty, New Zealand, was investigated using ground-penetrating radar (GPR). This technique allowed analysis of the evolution of the barrier, which is affected by tectonism, volcanism, and human influences. Sedimentary facies interpreted from the GPR include: prograding shoreface (including nearshore, shoreface, and eolian dune facies), truncated progradation and cut-and-fill, infill, and alluvial bank. The relationships of these structures suggest development that has varied over the barrier's history (approximately 8,000 years).
Interface and stress engineering in germanium metal-oxide-semiconductor field-effect-transistors for high performance application [electronic resource]
Keywords: Electrical Engineering

Germanium has been attracting great interests as a high mobility channel material for MOSFETs to replace silicon in LSI chips. Germanium also has advantages over any other high mobility material, such as high compatibility to Silicon LSI technologies, low temperature process which enable 3DIC integration with low thermal budget. In order to realize high performance Ge MOS integration in future technology nodes, device and process issues have to be thoroughly addressed and investigated. In this work, first, the property of metal/Ge contact was studied. Since Ge suffers from very strong Fermi-level pinning near its valence band, n-type metal/Ge contact causes high contact resistance whatever workfunction metal is used. New technique, which is insertion of ultrathin insulator between metal and Ge, was proposed and Fermi-level depinning was experimentally demonstrated. In the second part, radical oxidation was investigated for GeO2 growth for highly reliable interface gate dielectric in high-k/Ge gate stack. Although Ge does not have chemically stable native oxide unlike Si, GeO2 has been regarded as a promising interface gate dielectric with high-k dielectric capping. High density radical oxidation enables very low temperature oxidation and provides high quality GeO2 with low interface states. In the third part, the effects of stress in Ge NMOSFETs were studied. Stress engineering has been playing a key role in the current high performance Si LSI technologies and it can also enhance device performance of Ge MOSFETs. Mobility enhancement was experimentally achieved by applying uniaxial stress to Ge NMOSFETs and performance limit of Ge NMOSFET with uniaxial stress was also theoretically examined. It is clarified that stress engineering is effective in future technology nodes.
Interface-engineered Ge MOSFETs for future high performance CMOS applications [electronic resource]
Keywords: Electrical Engineering

As the semiconductor industry approaches the limits of traditional silicon CMOS scaling, introduction of performance boosters like novel materials and innovative device structures has become necessary for the future of CMOS. High mobility materials are being considered to replace Si in the channel to achieve higher drive currents and switching speeds. Ge has particularly become of great interest as a channel material, owing to its high bulk hole and electron mobilities. However, replacement of Si channel by Ge requires several critical issues to be addressed in Ge MOS technology. High quality gate dielectric for surface passivation, low parasitic source/drain resistance and performance improvement in Ge NMOS are among the major challenges in realizing Ge CMOS. Detailed characterization of gate dielectric/channel interface and a deeper understanding of mobility degradation mechanisms are needed to address the Ge NMOS performance problem and to improve PMOS performance. In the first part of this dissertation, the electrical characterization results on Ge NMOS and PMOS devices fabricated with GeON gate dielectric are presented. Carrier scattering mechanisms are studied through low temperature mobility measurements. For the first time, the effect of substrate crystallographic orientation on inversion electron and hole mobilities is investigated. Direct formation of a high-k dielectric on Ge has not given good results in the past. A good quality interface layer is required before the deposition of a high-K dielectric. In the second part of this dissertation, ozone-oxidation process is introduced to engineer Ge/insulator interface. Electrical and structural characterizations and stability analysis are carried out and high quality Ge/dielectric interface with low interface trap density is demonstrated. Detailed extraction of interface trap density distribution across the bandgap and close to band edges of Ge, using low temperature conductance and capacitance measurements is presented. Ge N-MOSFETs have exhibited poor drive currents and low mobility, as reported by several different research groups worldwide. In spite of the increasing interest in Ge, the major mechanisms behind poor Ge NMOS performance have not been completely understood yet. In the last part of this dissertation, the results on Ge NMOS devices fabricated with the ozone-oxidation and the low temperature source/drain activation processes are discussed. These devices achieve the highest electron mobility to-date, about 1.5 times the universal Si mobility. Detailed interface characterizations, trapping analyses and gated Hall device measurements are performed to identify the mechanisms behind poor Ge NMOS performance in the past.