698 research outputs found
Head Mounted Eye Tracking Aid for Central Visual Field Loss
No full textUniversity of Minnesota M.S.M.E. thesis. July 2016. Major: Mechanical Engineering. Advisor: Arthur Erdman. 1 computer file (PDF); viii, 137 pages.Age-Related Macular Degeneration results in central visual field loss (CFL) due to formation of central blind-spots or scotomas. Activities like reading are affected. We hypothesize that real-time remapping of lost information due to CFL onto a functional portion of the retina will improve visual performance. We have developed two hardware prototypes using a head-mounted display, integrated eye-tracker, and computer to remap and display images in real-time to the wearer. To test, in three different studies, normally-sighted subjects were asked to wear the head-mounted display with the built-in eye tracker. CFL was simulated by placing artificial circular scotomas ranging from 2° to 16° diameter over the gaze position, and reading speed was measured for the remapped and unremapped condition. We observed a statistically significant increase in mean reading speeds for the larger scotomas. Results indicate that the device shows promise for use with CFL patients.Gupta, Anshul. (2016). Head Mounted Eye Tracking Aid for Central Visual Field Loss. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/190600
Parallel Algorithm Scalability Issues in PetaFLOPS Architectures
No full textThe projected design space of petaFLOPS architectures entails exploitationof very large degrees of concurrency, locality of data access, and toleranceto latency. This puts considerable pressure on the design of parallelalgorithms capable of effectively utilizing increasing amounts of processingresources in a memory and bandwidth constrained environment. This aspect ofalgorithm design, also referred to as scalability analysis, is a keycomponent for guiding algorithm designers as well as hardware architects.By identifying bottlenecks to scalability and machine parameters thatinfluence these bottlenecks, scalability analysis provides insights toalleviating the bottlenecks in the context of the specific algorithm.In this paper, we motivate the need for, and benefits of scalabilityanalysis in the context of petaFLOPS systems. We overview variousscalability metrics and study their suitability to petaFLOPS system.We also present sample analysis of selected computational kernels fromdense linear algebra, fast fourier transforms, and data intensive applications(association rule mining). The objective of this analysis is to demonstratethe analysis framework and its use in identifying desirable architecturalfeatures as well the ability of these selected kernels to scale to petaFLOPSsystems.Garma, Ananth; Gupta, Anshul; Han, Euihong; Kumar, Vipin. (2001). Parallel Algorithm Scalability Issues in PetaFLOPS Architectures. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/215488
SRAM with buried power distribution to improve write margin and performance in advanced technology nodes
No full textCharacterization and modeling of hot carrier degradation in N-channel gate-all-around nanowire FETs
No full textCollective excitations in layered materials with momentum-resolved electron energy loss spectroscopy
No full textStrong Coulomb interactions are either suspected or known to play a prominent role in material classes such as high temperature superconductors, charge density waves, and Mott insulators among many others. These interactions are quantified by the charge density response function, chi(q,w) (or the closely related inverse dielectric function). The measurement of the energy- and momentum-resolved chi(q,w) over a large phase space of q and w, however, presents a significant experimental challenge. Traditional methods to measure chi(q,w) have suffered from either one or more major drawbacks. To address this problem, the development of a spectroscopic technique, momentum-resolved electron energy loss spectroscopy (M-EELS), was undertaken. Because many of the material classes that exhibit these unusual ground states tend to be layered or quasi-two dimensional, M-EELS presents a promising approach to measuring the energy- and momentum-resolved charge density response. Since the technique is not widely used, however, the M-EELS results obtained as part of this thesis were compared to other probes in the relevant ranges of phase space to ensure consistency. Furthermore, a theoretical framework was worked out to demonstrate explicitly the relationship between the scattering cross section and c(q,w). M-EELS experiments were conducted on a high-temperature superconductor, Bi2Sr2CaCu2O8+d, a charge density wave material, TiSe2, and a topological insulator, Bi2Se3. It was determined that the bosonic origin of quasiparticle kinks often seen in angle-resolved photoemission studies can be identified using M-EELS. Lastly, the observation of a novel electronic collective mode in TiSe2 is presented as strong evidence for an excitonic insulator phase in this compound.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2017-12-01The student, Anshul Kogar, accepted the attached license on 2015-08-28 at 14:26.The student, Anshul Kogar, submitted this Dissertation for approval on 2015-08-28 at 14:40.This Dissertation was approved for publication on 2015-09-08 at 14:22.DSpace SAF Submission Ingestion Package generated from Vireo submission #8678 on 2016-03-08 at 11:05:02Made available in DSpace on 2016-03-08T17:21:39Z (GMT). No. of bitstreams: 2
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Previous issue date: 2015-09-08Embargo set by: Seth Robbins for item 91482
Lift date: 2018-03-08T17:22:13Z
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Android game development with AppInventor
No full textThesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 94).AppInventor is an educational learning tool provided by MIT that allows users to build Android apps without any knowledge of programming. As AppInventor gains popularity amongst educators and students around the world, it will become increasingly important to ensure that the tool offers its users the breadth and depth of app-development functionality they desire. In anticipation of AppInventor's expanding role and influence in educational institutions worldwide (middle schools and high-schools, primarily), this thesis focuses on the age group of 3rd to 12th grade students, and on the topic that is of greatest interest to them: gaming, animation, and graphics. The aim of this thesis is to identify AppInventor's existing capabilities and limitations with respect to game development, and to implement ideas (both pedagogical and technological in nature) that will improve the diversity, complexity, aesthetic appeal, and performance of games that can be built using AppInventor. The author of this thesis believes that if AppInventor's game development capabilities can be augmented, the adoption rate of the tool and its popularity amongst school students will be impacted very positively. In this thesis, the author describes his personal experiences teaching AppInventor game development in India and USA, as well as the limitations (in teaching methodology and in AppInventor's feature set) that he identified through this experience. The author's primary contributions are the development of a hands-on curriculum for a 40-hour AppInventor Game Development course, and the implementation of several new features and components for AppInventor. The author will be traveling to China and India in Summer 2012 to test to what extent his creative curriculum and novel AppInventor modifications facilitate the development of games using AppInventor.by Anshul Bhagi.M.Eng
Interactions between auditory and visual motion mechanisms and the role of attention: psychophysics and quantitative models
No full textThe human brain continuously receives sensory input from the dynamic physical world via various sensory modalities. In many cases, a single physical event generates simultaneous input to more than one modality. For example, a ball hitting the ground generates both visual and auditory input. The human brain has developed mechanisms to take advantage of the correlations between inputs to different modalities to form a uniform and stable percept. Recently, there has been a lot of research interest, psychophysical, neurophysiological and computational, to explore the mechanisms involved in crossmodal interactions in general and auditory-visual interactions in particular.
The current thesis makes three significant contributions to the field of auditory-visual interactions. First, I designed a comprehensive study to psychophysically examine the interactions between auditory and visual motion mechanisms for three different motion configurations: horizontal, vertical and motion-in-depth. I showed that simultaneous presentation of a strong motion signal in one modality influences perception of a weak motion signal in the other modality both when the weak motion in presented in the visual, as well as in the auditory modality. I further observed that crossmodal aftereffects were induced only when subjects adapted to spatial motion in the visual modality and not in the auditory modality. However, adaptation to auditory spectral motion did induce vertical visual motion aftereffects. To my knowledge, this is the first report of auditory-induced visual aftereffects. Second, I conducted psychophysical experiments to study the effects of spectral attention on the visual and the auditory motion mechanisms and showed that there are similar attentional effects on motion mechanisms within the two modalities. Third, I developed a neurophysiologically relevant computational model to provide a possible explanation for crossmodal interactions between the auditory and the visual motion mechanisms. In addition, I developed a model that can explain the observed experimental findings on the role of spectral attention in modulating motion aftereffects. The results obtained from both the model simulations agree very closely with the human behavioral data obtained from the experiments.Ph.D.Includes bibliographical references (p. 139-144)
Application of HPC for power system operation and electricity market tools for power networks of the future
No full textDevelopment and application of SmartGrids or Intelligrids, including roll-out of smart meters and electrical vehicles, is of a great importance if the UK and other countries are to achieve significant carbon emission reductions and realize sustainable energy systems. These new grids will offer the opportunity to increase the level of renewable energy integrated into the system. They will also allow customers, including small households, to actively participate and adjust their demand depending on energy availability and price. This will further lead towards improved energy efficiency, as well as offer possibilities to reduce overall consumption and reduce or postpone investments into new large generation and infrastructure facilities. To achieve these goals, a number of technical, economical and policy issues need to be addressed and resolved. The development of new generations of extremely fast software tools that can solve power system problems with large number of nodes will also be important to help resolve these issues. For example, distribution system and network operators, as well as trading entities such as aggregators, will get a better coordination of system operation though the possibility to engage with even smaller generators, and especially smaller customers. This control at lower voltage levels will allow for the aggregation of responses which will then propagate to higher voltage levels. Currently, the discussion regarding the operation of future power systems is looking into two different options. One is to develop methodologies that will allow decentralization of network operation with the reduced level of coordination at the high level of system operation. However, the new software developed to exploit the benefits of the HPC architecture may open a possibility for businesses and policy makers to investigate and compare operation of centralized vs. decentralized operation over areas with large number of participants.. These new HPC power system analysis tools will enable more frequent price signal calculations and bring the possibility to define policies which will ensure engagement with customers to reduce their energy consumption or shift it towards offpeak periods, as well as allow for the coordination of charging of electric vehicles and their use as storage devices. Such tools will be useful for both decentralized and centralized operation, however they will be crucial for the latter. This chapter will first give an overview of the changes in future power system operation and then outline power system analysis tools such as power flow, optimal power flow, generation scheduling and the security assessment. It will then discuss current status of the parallel techniques and HPC applications for the power system operation tools. It will also discuss the formulation requirements, achievements and possible obstacles in the application of techniques suitable for HPC and for power system operation problems such as power flow, optimal power flow (OPF), security constrained OPF. Finally, it will look how new developments in the HPC/Numerical Analysis area, and even more powerful Extreme Computing together with new algorithms developed for this next-step class of machines may help improve power system operation and electricity markets tools
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