ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- All Subjects: Machine Learning
Description
With the breakdown of Dennard scaling, computer architects can no longer rely on integrated circuit energy efficiency to scale with transistor density, and must under-clock or power-gate parts of their designs in order to fit within given power budgets. Hardware accelerators may improve energy efficiency of some compute-intensive tasks, but as more tasks are accelerated, the general-purpose portions of workloads account for a larger share of execution time while also leaving less instruction, data, or task-level parallelism to exploit. Adaptive computing systems have potential to address these challenges by modifying their behavior at runtime. Adaptation requires runtime decision-making, which can be performed both in hardware and software. While software-based decision-making is more flexible and can execute higher complexity operations compared to hardware, it also incurs a significant latency and power overhead. Hardware designs are more limited in the space of decisions they can make, but have direct access to their own internal microarchitectural states and can make faster decisions, allowing for better-informed adaptation and extracting previously unobtainable performance and security benefits. In this dissertation I study (i) the viability and trade-offs of general-purpose adaptive systems, (ii) the difficulty and complexity of making adaptation decisions, and (iii) how time spent in the observation-analysis-adaptation cycle affects adaptation benefits. I introduce techniques for (a) modeling and understanding high performance computing systems and microarchitecture, (b) enabling hardware learning and decision-making through low-latency networks, and (c) on securing hardware designs using runtime decision-making. I propose an always-awake and active learning `hardware nervous system' pervasive throughout the chip that can reason about the individual hardware module performance, energy usage, and security. I present the design and implementation of (1) a reference architecture and (2) a microarchitecture-aware static binary instrumentation tool. Finally, I provide results showing (1) that runtime adaptation is a necessary to continue improving performance on general-purpose tasks, (2) that significant performance loss and performance variation happens under the ISA-level, and is unobservable without hardware support, and (3) that hardware must possess decision-making and ‘self-awareness’ capabilities at the microarchitecture level in order to efficiently use its own faculties.
ContributorsIsakov, Mihailo (Author) / Kinsy, Michel (Thesis advisor) / Shrivastava, Aviral (Committee member) / Rudd, Kevin (Committee member) / Gadepally, Vijay (Committee member) / Arizona State University (Publisher)
Created2022
Description
Ultra High Performance (UHP) cementitious binders are a class of cement-based materials with high strength and ductility, designed for use in precast bridge connections, bridge superstructures, high load-bearing structural members like columns, and in structural repair and strengthening. This dissertation aims to elucidate the chemo-mechanical relationships in complex UHP binders to facilitate better microstructure-based design of these materials and develop machine learning (ML) models to predict their scale-relevant properties from microstructural information.To establish the connection between micromechanical properties and constitutive materials, nanoindentation and scanning electron microscopy experiments are performed on several cementitious pastes. Following Bayesian statistical clustering, mixed reaction products with scattered nanomechanical properties are observed, attributable to the low degree of reaction of the constituent particles, enhanced particle packing, and very low water-to-binder ratio of UHP binders. Relating the phase chemistry to the micromechanical properties, the chemical intensity ratios of Ca/Si and Al/Si are found to be important parameters influencing the incorporation of Al into the C-S-H gel.
ML algorithms for classification of cementitious phases are found to require only the intensities of Ca, Si, and Al as inputs to generate accurate predictions for more homogeneous cement pastes. When applied to more complex UHP systems, the overlapping chemical intensities in the three dominant phases – Ultra High Stiffness (UHS), unreacted cementitious replacements, and clinker – led to ML models misidentifying these three phases. Similarly, a reduced amount of data available on the hard and stiff UHS phases prevents accurate ML regression predictions of the microstructural phase stiffness using only chemical information. The use of generic virtual two-phase microstructures coupled with finite element analysis is also adopted to train MLs to predict composite mechanical properties. This approach applied to three different representations of composite materials produces accurate predictions, thus providing an avenue for image-based microstructural characterization of multi-phase composites such UHP binders. This thesis provides insights into the microstructure of the complex, heterogeneous UHP binders and the utilization of big-data methods such as ML to predict their properties. These results are expected to provide means for rational, first-principles design of UHP mixtures.
ML algorithms for classification of cementitious phases are found to require only the intensities of Ca, Si, and Al as inputs to generate accurate predictions for more homogeneous cement pastes. When applied to more complex UHP systems, the overlapping chemical intensities in the three dominant phases – Ultra High Stiffness (UHS), unreacted cementitious replacements, and clinker – led to ML models misidentifying these three phases. Similarly, a reduced amount of data available on the hard and stiff UHS phases prevents accurate ML regression predictions of the microstructural phase stiffness using only chemical information. The use of generic virtual two-phase microstructures coupled with finite element analysis is also adopted to train MLs to predict composite mechanical properties. This approach applied to three different representations of composite materials produces accurate predictions, thus providing an avenue for image-based microstructural characterization of multi-phase composites such UHP binders. This thesis provides insights into the microstructure of the complex, heterogeneous UHP binders and the utilization of big-data methods such as ML to predict their properties. These results are expected to provide means for rational, first-principles design of UHP mixtures.
ContributorsFord, Emily Lucile (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Mobasher, Barzin (Committee member) / Chawla, Nikhilesh (Committee member) / Hoover, Christian G. (Committee member) / Maneparambil, Kailas (Committee member) / Arizona State University (Publisher)
Created2020