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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Partitioning Uncertainty for Non-Ergodic Probabilistic Seismic Hazard Analyses

Dawood, Haitham Mohamed Mahmoud Mousad 29 October 2014 (has links)
Properly accounting for the uncertainties in predicting ground motion parameters is critical for Probabilistic Seismic Hazard Analyses (PSHA). This is particularly important for critical facilities that are designed for long return period motions. Non-ergodic PSHA is a framework that allows for this proper accounting of uncertainties. This, in turn, allows for more informed decisions by designers, owners and regulating agencies. The ergodic assumption implies that the standard deviation applicable to a specific source-path-site combination is equal to the standard deviation estimated using a database with multiple source-path-site combinations. The removal of the ergodic assumption requires dense instrumental networks operating in seismically active zones so that a sufficient number of recordings are made. Only recently, with the advent of networks such as the Japanese KiK-net network has this become possible. This study contributes to the state of the art in earthquake engineering and engineering seismology in general and in non-ergodic seismic hazard analysis in particular. The study is divided in for parts. First, an automated protocol was developed and implemented to process a large database of strong ground motions for GMPE development. A comparison was conducted between the common records in the database processed within this study and other studies. The comparison showed the viability of using the automated algorithm to process strong ground motions. On the other hand, the automated algorithm resulted in narrower usable frequency bandwidths because of the strict criteria adopted for processing the data. Second, an approach to include path-specific attenuation rates in GMPEs was proposed. This approach was applied to a subset of the KiK-net database. The attenuation rates across regions that contains volcanoes was found to be higher than other regions which is in line with the observations of other researchers. Moreover, accounting for the path-specific attenuation rates reduced the aleatoric variability associated with predicting pseudo-spectral accelerations. Third, two GMPEs were developed for active crustal earthquakes in Japan. The two GMPEs followed the ergodic and site-specific formulations, respectively. Finally, a comprehensive residual analysis was conducted to find potential biases in the residuals and propose models to predict some components of variability as a function of some input parameters. / Ph. D.
12

Bottlenecks of motion processing during a visual glance: the leaky flask model

Ögmen, H., Ekiz, O., Huynh, D., Bedell, H.E., Tripathy, Srimant P. 31 December 2013 (has links)
Yes / Where do the bottlenecks for information and attention lie when our visual system processes incoming stimuli? The human visual system encodes the incoming stimulus and transfers its contents into three major memory systems with increasing time scales, viz., sensory (or iconic) memory, visual short-term memory (VSTM), and long-term memory (LTM). It is commonly believed that the major bottleneck of information processing resides in VSTM. In contrast to this view, we show major bottlenecks for motion processing prior to VSTM. In the first experiment, we examined bottlenecks at the stimulus encoding stage through a partial-report technique by delivering the cue immediately at the end of the stimulus presentation. In the second experiment, we varied the cue delay to investigate sensory memory and VSTM. Performance decayed exponentially as a function of cue delay and we used the time-constant of the exponential-decay to demarcate sensory memory from VSTM. We then decomposed performance in terms of quality and quantity measures to analyze bottlenecks along these dimensions. In terms of the quality of information, two thirds to three quarters of the motion-processing bottleneck occurs in stimulus encoding rather than memory stages. In terms of the quantity of information, the motion-processing bottleneck is distributed, with the stimulus-encoding stage accounting for one third of the bottleneck. The bottleneck for the stimulus-encoding stage is dominated by the selection compared to the filtering function of attention. We also found that the filtering function of attention is operating mainly at the sensory memory stage in a specific manner, i.e., influencing only quantity and sparing quality. These results provide a novel and more complete understanding of information processing and storage bottlenecks for motion processing. / Supported by R01 EY018165 and P30 EY007551 from the National Institutes of Health (NIH).
13

Active Regulation of Speed During a Simulated Low-altitude Flight Task: Altitude Matters!

Bennett, April M. 27 December 2006 (has links)
No description available.
14

Cognitive influences on sensory processing of visual motion / Kognitive Einflüsse auf die sensorische Verarbeitung visueller Bewegung

Katzner, Steffen 04 July 2006 (has links)
No description available.
15

Effects of Selective Attention on Sensory Processing of Visual Motion / Der Einfluss selektiver Aufmerksamkeit auf die sensorische Verarbeitung visueller Bewegung

Busse, Laura 31 October 2006 (has links)
No description available.
16

Attention and Adaptation in Visual Motion Processing / Aufmerksamkeit und Adaptation in der visuellen Bewegungswahrnehmung

Pieper, Florian 30 October 2007 (has links)
No description available.
17

Perception of visual motion speed in human und monkey / Die Wahrnehmung der visuellen Geschwindigkeit bei Mensch und Affe

Boyraz, Pinar 19 April 2007 (has links)
No description available.
18

Psychophysics and physiology of attentional influences on visual motion processing / Psychophysik und Physiologie von Aufmerksamkeitseinflüssen auf die Verarbeitung visueller Bewegung

Anton-Erxleben, Katharina 08 May 2008 (has links)
No description available.

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