Matching Items (3)
Filtering by
- All Subjects: Methodology
- Creators: Bates, Jordan T
- Creators: Clark, Lawrence
Description
The space environment comprises cosmic ray particles, heavy ions and high energy electrons and protons. Microelectronic circuits used in space applications such as satellites and space stations are prone to upsets induced by these particles. With transistor dimensions shrinking due to continued scaling, terrestrial integrated circuits are also increasingly susceptible to radiation upsets. Hence radiation hardening is a requirement for microelectronic circuits used in both space and terrestrial applications.
This work begins by exploring the different radiation hardened flip-flops that have been proposed in the literature and classifies them based on the different hardening techniques.
A reduced power delay element for the temporal hardening of sequential digital circuits is presented. The delay element single event transient tolerance is demonstrated by simulations using it in a radiation hardened by design master slave flip-flop (FF). Using the proposed delay element saves up to 25% total FF power at 50% activity factor. The delay element is used in the implementation of an 8-bit, 8051 designed in the TSMC 130 nm bulk CMOS.
A single impinging ionizing radiation particle is increasingly likely to upset multiple circuit nodes and produce logic transients that contribute to the soft error rate in most modern scaled process technologies. The design of flip-flops is made more difficult with increasing multi-node charge collection, which requires that charge storage and other sensitive nodes be separated so that one impinging radiation particle does not affect redundant nodes simultaneously. We describe a correct-by-construction design methodology to determine a-priori which hardened FF nodes must be separated, as well as a general interleaving scheme to achieve this separation. We apply the methodology to radiation hardened flip-flops and demonstrate optimal circuit physical organization for protection against multi-node charge collection.
Finally, the methodology is utilized to provide critical node separation for a new hardened flip-flop design that reduces the power and area by 31% and 35% respectively compared to a temporal FF with similar hardness. The hardness is verified and compared to other published designs via the proposed systematic simulation approach that comprehends multiple node charge collection and tests resiliency to upsets at all internal and input nodes. Comparison of the hardness, as measured by estimated upset cross-section, is made to other published designs. Additionally, the importance of specific circuit design aspects to achieving hardness is shown.
This work begins by exploring the different radiation hardened flip-flops that have been proposed in the literature and classifies them based on the different hardening techniques.
A reduced power delay element for the temporal hardening of sequential digital circuits is presented. The delay element single event transient tolerance is demonstrated by simulations using it in a radiation hardened by design master slave flip-flop (FF). Using the proposed delay element saves up to 25% total FF power at 50% activity factor. The delay element is used in the implementation of an 8-bit, 8051 designed in the TSMC 130 nm bulk CMOS.
A single impinging ionizing radiation particle is increasingly likely to upset multiple circuit nodes and produce logic transients that contribute to the soft error rate in most modern scaled process technologies. The design of flip-flops is made more difficult with increasing multi-node charge collection, which requires that charge storage and other sensitive nodes be separated so that one impinging radiation particle does not affect redundant nodes simultaneously. We describe a correct-by-construction design methodology to determine a-priori which hardened FF nodes must be separated, as well as a general interleaving scheme to achieve this separation. We apply the methodology to radiation hardened flip-flops and demonstrate optimal circuit physical organization for protection against multi-node charge collection.
Finally, the methodology is utilized to provide critical node separation for a new hardened flip-flop design that reduces the power and area by 31% and 35% respectively compared to a temporal FF with similar hardness. The hardness is verified and compared to other published designs via the proposed systematic simulation approach that comprehends multiple node charge collection and tests resiliency to upsets at all internal and input nodes. Comparison of the hardness, as measured by estimated upset cross-section, is made to other published designs. Additionally, the importance of specific circuit design aspects to achieving hardness is shown.
ContributorsShambhulingaiah, Sandeep (Author) / Clark, Lawrence (Thesis advisor) / Holbert, Keith E. (Committee member) / Seo, Jae sun (Committee member) / Allee, David (Committee member) / Arizona State University (Publisher)
Created2015
Description
I began this thesis because I was confused about economics. I wondered why there were so many different models. I didn't understand how they fit together. I was also confused by the assumptions being made. For instance, the assumption that humans are rational utility-maximizers did not seem to agree with my own experiences. With my director Dr. Edward Schlee's help, my thesis has become an inquiry into the state of economic methodology, both in theory and in practice. The questions that drive this paper are: How do economists choose between theories? What is the purpose of economic theory? What is the role of empirical data in assessing models? What role do assumptions play in theory evaluation, and should assumptions make sense? Part I: Methodology is the theoretical portion of the paper. I summarize the essential arguments of the two main schools of thought in economic methodology, and argue for an updated methodology. In Part II: A case study: The expected utility hypothesis, I examine methodology in practice by assessing a handful of studies that seek to test the expected utility hypothesis. Interestingly, I find that there is a different between what economists say they are doing, and what they actually seem to be doing. Throughout this paper, I restrict my analysis to microeconomic theory, simply because this is the area with which I am more familiar. I intend this paper to be a guide for my fellow students and rising economists, as well as for already practicing economists. I hope it helps the reader better understand methodology and improve her own practice.
ContributorsKang, Dominique (Author) / Schlee, Edward (Thesis director) / Schoellman, Todd (Committee member) / Boerner, Rochus (Committee member) / Barrett, The Honors College (Contributor)
Created2013-05
Description
Network analysis is a key conceptual orientation and analytical tool in the social sciences that emphasizes the embeddedness of individual behavior within a larger web of social relations. The network approach is used to better understand the cause and consequence of social interactions which cannot be treated as independent. The relational nature of network data and models, however, amplify the methodological concerns associated with inaccurate or missing data. This dissertation addresses such concerns via three projects. As a motivating substantive example, Project 1 examines factors associated with the selection of interaction partners by students at a large urban high school implementing a reform which, like many organizational improvement initiatives, is associated with a theory of change that posits changes to the structuring of social interactions as a central causal pathway to improved outcomes. A distinctive aspect of the data used in Project 1 is that it was a complete egocentric network census – in addition to being asked about their own relationships, students were asked about the relationships between alters that they nominated in the self-report. This enables two unique examinations of methodological challenges in network survey data collection: Project 2 examines the factors related to how well survey respondents assess the strength of social connections between others, finding that "informant" competence corresponds positively with their social proximity to target dyad as well as their centrality in the network. Project 3 explores using such third-party reports to augment network imputation methods, and finds that incorporating third-party reports into model-based methods provides a significant boost in imputation accuracy. Together these findings provide important implications for collecting and extrapolating data in research contexts where a complete social network census is highly desirable but infeasible.
ContributorsBates, Jordan T (Author) / Maroulis, Spiro J (Thesis advisor) / Kang, Yun (Thesis advisor) / Frank, Kenneth A. (Committee member) / Arizona State University (Publisher)
Created2019