VictorJuiz/thesis huggingface dataset:
Design and optimization of processors for energy efficiency [electronic resource] : a joint architecture-circuit approach
Keywords: Electrical Engineering

The design of a digital system for energy efficiency often requires the analysis of trade-offs in both the circuit design and the architecture. To assist with this analysis, we present a novel optimization framework for performing joint design space exploration of architectural and circuit design spaces. In this approach, we use statistical inference/regression techniques to create a models of large micro-architectural design spaces from a small number of simulation samples. We then characterize the design trade-offs of each of the underlying circuits and integrate these with the higher level architectural models to define the joint circuit-architecture design space. By using posynomial forms for all our models, we are then able to formulate the optimization problem as a geometric program, enabling the use of convex optimization tools to efficiently search the joint design space. We apply this framework to study energy-performance trade-offs in general purpose microprocessor design. We consider six different high-level architectures, from a simple single-issue in-order processor to a quad-issue out-of-order processor. Optimizing across this space for different performance targets, we identify the order in which high-level architectural features should be considered as one seeks more performance; starting with a low-power single-issue in-order design, to increase performance efficiently one should first increase the issue-width to two, then add out-of-order execution, and finally increase the issue-width further to end with the quad-issue out-of-order processor if maximum performance is required. Extending our study to include the voltage scaling, we find that the results change dramatically. Our results show that architectural and circuit design techniques have a very rapidly changing marginal cost profile, with many options having either very low or very high marginal costs. Since the marginal cost of obtaining additional performance through voltage changes more slowly, we find that when we optimize the system jointly with voltage, the set of efficient architecture/circuit design features become confined to a small sweet spot for a large part of the design space. Thus, when optimized with voltage as a parameter, two high-level architectures--the dual-issue in-order processor and the dual-issue out-of-order processor--are efficient over almost the complete range of performance targets.
Design and process for three-dimensional heterogeneous integration [electronic resource]
Keywords: Electrical Engineering

Since the invention of the integrated circuit (IC) in the late 1950s, the semiconductor industry has experienced dramatic growth driven by both technology and manufacturing improvements. Over the past 40 years, the industry's growth trend has been predicted by Moore's law, and driven by the constant electrical field scaling design methodology. While the intrinsic performance of each device improves over generations, the corresponding interconnects do not. To alleviate this interconnect issue, a three-dimensional (3D) integration concept of transforming longer side to side interconnects into shorter vertical vias by using multiple active layers has attracted much attention. The focus of this thesis is on providing the foundation for 3D heterogeneous integration by investigating methods of growing single crystal materials on the silicon platform and the subsequent low-temperature process flow, through experimental demonstration, theoretical modeling and device structure simplification. First, thin film single crystal GaAs and GaSb were grown on dielectric layers on bulk silicon substrates by the rapid melt growth (RMG) method, using both rapid thermal annealing (RTA) and laser annealing. The relationship between stoichiometry and the crystal structure is discussed according to the theoretical phase diagram and the experimental results. A modified RMG structure is also proposed and demonstrated to solve the potential issue involved in integrating the RMG method into a three-dimensional integrated circuits (3D-IC) process with thick isolation layers. In order to estimate the outcome of the crystallization and to provide further understanding of the physics behind this RMG process, compact models are derived based on classical crystallization theory. Mathematical models including the geometry, the thermal environment and the outcome of the crystallization are built. The initial cooling rate is identified as the key factor for the RMG process. With the ability of integrating multiple materials on silicon substrates, the subsequent process flows using low-temperature-fabrication or simplified device structures are proposed and evaluated to achieve high density 3D integration. A "bonding substrate/monolithic contact" approach is proposed to relieve the thermal constraint from getting the starting single crystal layer without sacrificing the interconnect performance. A low-temperature process using germanium as the channel material is also discussed. Finally, gated thin film resistor structures are designed and compared to the conventional MOSFET structure with a focus on their relative performance and process complexity trade-off for future 3D-IC implementation.
The design and validation of an automatically-scored constructed-response item type for measuring graphical representation skill [electronic resource]
Keywords: Education.

Graphical representation--the construct that consists of shifting between graphical and non-graphical (e.g., textual, tabular) representations of a problem situation--has a prominent place in state and national standards, and is a skill required for information producers and consumers alike. But because of the cost of hand-scoring items that would require students to produce graphs, current measurement of this important skill is often limited to multiple-choice items that test only students' ability to consume graphs. Because of this misalignment, teachers and students may focus instruction and learning on graph consumption and neglect the important skill of graph production. This work aims to align measurement with educator expectations by introducing an automated scoring system for "graphical-response" items--items that present the student with a problem situation and ask them to sketch a graph that represents that situation. In this dissertation, an interpretive argument (Kane, 1992, 2006) justifying the use of automatically-scored graphical response items to measure graphical representation skill is articulated and then tested through an empirical study. This validation study supports the use of automatically-scored graphical-response items in low-stakes formative assessments, and suggests that with more comprehensive empirical evidence these items could be viable in higher-stakes assessments as well. The dissertation concludes by examining limitations of the study and by detailing potential formative and summative applications.
Design of a doppler-aided GPS navigation system for weak signals caused by strong ionospheric scintillation [electronic resource]
Keywords: Aeronautics and Astronautics

The fundamental tasks of a Global Positioning System (GPS) receiver are signal tracking and noise rejection. The essence of this dissertation is investigating the balance between the aforementioned objectives; taking advantage of the noise immunity property of external sensors, and designing novel integrated tracking architectures to advance the performance of a GPS receiver under strong interference conditions. Specifically, the problem of interest is resolving the interference due to ionospheric scintillation on the GPS receiver used in aviation navigation. Using GPS for landing aircraft in equatorial regions is more difficult than in other regions because ionospheric scintillation is prevalent. Ionospheric scintillation causes amplitude fades of 20 dB or more, and an increase in the phase jitter. This research evaluates techniques to enhance a GPS receiver's ability to overcome ionospheric scintillation. To validate the designed GPS receiver, a GPS channel model for aircraft landing in equatorial regions is built based on the use of a high fidelity GPS constellation simulator, a clock emulator, and real GPS data from the equator that contains an abundance of ionospheric scintillation. The results of this research demonstrate that the integration of a GPS receiver with a low-cost inertial navigation system provides the capability to operate continuously during periods of strong scintillation. In addition, so-called vector processing also shows promise for a less severe scintillation environment. Various combinations of receiver tracking architectures and aiding methods have been analyzed to quantify the sensitivity improvement of an "aided" GPS receiver.
Design of a multilateral market for heterogeneous goods [electronic resource]
Keywords: Business.

This dissertation studies markets for heterogeneous goods or services using mechanism design theory. Each participant's utility is quasi-linear in money, and depend upon the allocation that he gets - thus, a participant's privately known 'type' is multidimensional. The key properties are individual rationality, incentive compatibility, budget balance, efficiency, and stability against coalitional deviations. In the second chapter, for each combination of desirable properties, I derive an assignment process with these properties in the form of a corresponding direct-revelation game, or I show that it does not exist. The main results characterize mechanisms that are ex post incentive compatible in combination with other properties. Then I apply these main results to specific applications including a labor market, a buyer-seller market, a housing market, and a partnership formation problem. In the third chapter, I study a two-sided matching market with complete information. I define the median stable matching for such markets with wages and prove constructively that it exists. In the fourth chapter, I analyze position auctions with general pricing rules. In these auctions, there are several items to be allocated which are commonly ranked by agents with unit demand. The preeminent example of position auctions is the "generalized second-price'' (GSP) auction used by major search engines to sell online advertising. \cite{edossc07} establish that the ex post equilibrium of the GSP auction and the dominant strategy equilibrium of the Vickrey-Clarke-Groves mechanism have identical payoffs. I extend their result to ascending auctions with general pricing rules where the price for an item depends on the bids of agents who win lower ranked items continuously, even if the agents have multidimensional types.
Design of robust medium access control in wireless networks with channel fading using game theory [electronic resource]
Keywords: Electrical Engineering

Many medium-access-control (MAC) protocols for wireless networks are designed based on the assumption that all mobile stations (MSs) follow the policy set by the protocol; hence, these protocols are not robust to the self-interested behavior of MSs. However, MSs become more intelligent and flexible, so that they can adapt their MAC policies to accommodate their own interests. Therefore, another requirement arises in the design of MAC protocols: robustness to self-interested behavior. For robustness, this thesis suggests using Nash equilibria (NE) as MAC policies. Since any deviation of a station from an NE penalizes the station, the networks operating in NEs achieve robustness by preventing selfish stations from violating the access protocol. This thesis considers two random-access networks, slotted ALOHA and CSMA, and a single-cell cellular network in fading environment where the channel gains are time-varying. For random-access networks, both collision channels and capture channels are considered, while interference channels are considered for cellular networks. After modeling these networks as non-cooperative games, this thesis establishes the existence and uniqueness of NEs of the games and investigate the characteristics of the NEs. It is shown that the NEs of random access systems are threshold strategies, allowing a station with a high channel gain a better chance to access the channel; thus, ensuring multi-user diversity as well as robustness when operating in NEs. For cellular systems, it is established that an NE is a truncated channel inversion (TCI), a celebrated power allocation policy, under some conditions. As a practical consideration, simple distributed algorithms is suggested to enable MSs to converge to the NEs without global knowledge of the system and any coordination among MSs.
The design, synthesis, and biological evaluation of molecular transporter conjugates and their encapsulation inside nanoparticles for drug delivery applications [electronic resource]
Keywords: Chemistry.

Biological barriers prevent the uptake of many potentially harmful xenobiotics yet also limit the delivery and cellular entry of a variety of drugs to their targets. One approach to this problem selects only those compounds with appropriate properties, namely solubility in polar biological fluids yet also able to pass through the nonpolar cellular membrane. This restriction would therefore preclude the use of many polar (e.g. siRNA) and nonpolar (e.g. Taxol) compounds whose inherent physical properties cause problems with formulation, distribution or bioavailability. The research described herein utilizes an alternative strategy that involves molecular transporters, which are agents that, when attached to poorly soluble or poorly bioavailable drugs, produce conjugates that exhibit excellent water solubility and simultaneously an increased ability to cross tissue and cell barriers. Bioactivatable molecular transporter conjugates of the immunosuppressant drug Cyclosporin A incorporating disulfide linkers were developed, evaluated for their biological activity in vitro, and administered topically in an in vivo mouse model. In addition to the inherent physical properties limitation that prevents drug passage across the cell membrane, another significant contributor to the failure of many therapeutics is the overexpression of membrane proteins (e.g. P-glycoprotein or Pgp) that mediate the unidirectional efflux of drugs out of target cells, often doing so prior to the drug reaching its intracellular target. Bioactivatable oligoarginine transporter conjugates of Taxol, a substrate for Pgp, were prepared and shown to overcome efflux-mediated resistance in primary human ovarian cancer tissue ex vivo. The encapsulation of transporter conjugates inside biodegradable polymeric nanoparticles was also investigated as a way to achieve sustained release of transporter drug conjugates over extended periods of time, thereby avoiding metabolism or toxicity problems associated with a bolus administration of therapeutic agents. Nanoparticles encapsulating transporter-probe conjugates were formed using two different methods, and shown to release their encapsulated cargo over time under biologically relevant conditions.
Detecting and characterizing large-scale human brain networks [electronic resource]
Keywords: Biomedical Informatics.

Understanding human brain function is one of the most important endeavors in modern science. There is growing evidence that cognitive functions are executed by large-scale networks, comprising multiple interacting anatomically-connected brain areas. Although considerable progress has been made in understanding which specific brain areas are involved in particular cognitive functions, very little is known about the integrative functioning of large-scale brain networks. This is due in part to the lack of methods to pursue this line of research. This dissertation describes computational methods for detecting and characterizing large-scale human brain networks, combining data from task-free functional magnetic resonance imaging (fMRI) and structural diffusion tensor imaging (DTI), two complementary brain imaging modalities. Application of our methods to task-free fMRI and DTI data obtained from a wide range of subject populations provided new insights into how large-scale human brain networks develop, mature, and get disrupted in psychiatric and neurological disorders. More generally, this work demonstrates the power of our multimodal network-analytic approach to obtain a system-level understanding of brain function across the human lifespan.
Detection and correction of patient motion in magnetic resonance imaging [electronic resource]
Keywords: Electrical Engineering

Due to the sequential nature of magnetic resonance imaging (MRI) data acquisition, correction of image artifacts originating from involuntary patient motion is essential for reliable diagnostic quality. Especially during MRI scans of certain patient populations such as children, elderly or patients with certain medical conditions (e.g. stroke, Parkinson's), motion correction methods must be incorporated into the MR imaging protocol for adequate image quality. With increased demands for higher resolution or time-resolved examinations (e.g. functional MRI), examination times also increase and even willing patients might have trouble staying still during the course of the examination. The first part of this thesis provides a method for retrospective correction of head motion artifacts using a multi-shot spiral-in \& out readout and parallel-imaging based iterative image reconstruction. The spiral-in part provided a low resolution image that was used for measurement of head motion. Due to rotational motion, locally undersampled areas appear in MR acquisition space (i.e., k-space), which violate the Nyquist theorem and cause artifacts even after motion correction. These artifacts were addressed through the data redundancy provided by multiple receiver channels that is present in modern receiver coils and an iterative conjugate-gradient based reconstruction. This method was then applied to diffusion tensor imaging (DTI) with multi-shot readout. Since DTI uses directional gradients to encode diffusion, rotational motion causes the image contrast to change, and it becomes incorrect to combine data with varying diffusion encodings on them. To address this issue, a non-linear conjugate gradient based reconstruction is presented and it is shown that this method provided more accurate description of white matter pathways compared to traditional methods. In the second part of this thesis, a prospective motion correction system using an optical tracking device is presented. Such systems are preferable compared to retrospective navigator-based methods due to various reasons, such as ability to perform motion correction independent of the MR data acquisition and immunity to spin history effects. The system proposed used a single camera mounted on the head coil and a self-encoded checkerboard marker mounted on the patient's forehead. Results on structural and diffusion imaging revealed that prospective motion correction outperforms retrospective navigator-based schemes. In the last part of the thesis, entropy-based retrospective autofocusing was used in combination with motion data obtained from prospective tracking to remove residual motion artifacts in the images. This method was especially useful for removing errors caused by inaccurate cross-calibration between the scanner and camera frame-of-references. It was also shown that prospective tracking can be the enabling technology for autofocusing in 3D acquisitions.
Detection and quantitative characterization of biomolecular interactions with microfluidic mechanical trapping [electronic resource]
Keywords: Applied Physics

In the era of rapid high-throughput DNA sequencing and increasing bioinformatic capabilities to analyze large amounts of biological data, it is especially important to continue to develop high-throughput experimental proteomic methods. Probing physical interactions among proteins and nucleic acids is a powerful approach to gain insight into their functional relationships. Microfluidic tools are of great potential value to this field because they make it possible to run hundreds or thousands of independent experiments in parallel and at a high spatial density. Here I present and explain MITOMI (mechanically induced trapping of molecular interactions), an in vitro method that was initially created to measure the affinities of transcription factors binding to DNA. I contributed to the development of the system so it could be applied to mapping protein-protein interaction networks, and used it to study the interactions of E. coli RNA polymerase in order to better understand the regulation of bacterial transcription. I also extended the utility of MITOMI by adapting it to be able to measure interaction kinetics and to more efficiently measure affinities. With the ability to discover interactions at a large scale and to quantitatively characterize them on the same platform, MITOMI constitutes a valuable contribution to proteomic methodology.
Devaluing Black space [electronic resource] : Black locations as targets of housing and environmental discrimination
Keywords: Psychology

Do spaces have races? Why might space-race associations matter? Across four studies, participants attached racial meaning to a range of locations, as well as negatively stereotyped and reported feeling less connected to Black spaces in particular. Negative stereotyping and lack of connection to Black space explained why these spaces experienced both housing and environmental discrimination. Studies 1 and 2 participants generated raced spaces and then rated the extent to which they thought of these locations (i.e. inner cities, suburbs) as White or Black. The more Black spaces were, the less White they were, showing participants made clear distinctions between these two types of spaces. Further, the Black spaces were rated more negatively than the White spaces, showing participants devalued Black space. Study 3 expanded this finding by manipulating the race of one location—a house for sale by a Black or White family. Participants gave the Black house, relative to the White, a lower evaluation (i.e. they thought it was worth less and were less eager to move there). The Black house received this lower evaluation because participants negatively stereotyped it. They imagined the neighborhood surrounding it to be lower quality than the neighborhood they imagined around the White house (i.e. less safe, lower quality schools and municipal services). Additionally, participants reported feeling less connected to the neighborhood around the Black house, which also helped to explain its lower evaluation. Study 4 participants again discriminated against Black space—this time in the environmental domain. Participants read a proposal to place a potentially polluting chemical plant near a majority Black or White neighborhood. They reported less opposition to this plant when the nearby neighborhood was Black. This Black space received less environmental protection because participants were more likely to think it already housed other industrial facilities (industrial space stereotype) and again because they reported feeling less connected to it. These results are important not only because they expand theory on racial discrimination, stereotyping, and sense of place, but also because they provide an enhanced understanding of the causal role race plays in producing and maintaining disparities in access to high quality, healthy living spaces.