Browsing by Subject "Probabilistic modeling"
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Item Open Access Detection of compound structures using multiple hierarchical segmentations(IEEE, 2014) Akçay, Hüseyin Gökhan; Aksoy, SelimIn this paper, we present a method for automatic compound structure detection in high-resolution images. Given a query compound structure, our aim is to detect coherent regions with similar spatial arrangement and characteristics in multiple hierarchical segmentations. A Markov random field is constructed by representing query regions as variables and connecting the vertices that are spatially close by edges. Then, a maximum entropy distribution is assumed over the query region process and selection of similar region processes among a set of region hierarchies is achieved by maximizing the query model. Experiments using WorldView-2 images show the efficiency of probabilistic modeling of compound structures. © 2014 IEEE.Item Open Access Temperature-dependent emission kinetics of colloidal semiconductor nanoplatelets strongly modified by stacking(American Chemical Society, 2016) Erdem, O.; Olutas M.; Guzelturk, B.; Kelestemur Y.; Demir, Hilmi VolkanWe systematically studied temperature-dependent emission kinetics in solid films of solution-processed CdSe nanoplatelets (NPLs) that are either intentionally stacked or nonstacked. We observed that the steady-state photoluminescence (PL) intensity of nonstacked NPLs considerably increases with decreasing temperature, whereas there is only a slight increase in stacked NPLs. Furthermore, PL decay time of the stacked NPL ensemble is comparatively much shorter than that of the nonstacked NPLs, and this result is consistent at all temperatures. To account for these observations, we developed a probabilistic model that describes excitonic processes in a stack using Markov chains, and we found excellent agreement between the model and experimental results. These findings develop the insight that the competition between the radiative channels and energy transfer-assisted hole trapping leads to weakly temperature-dependent PL intensity in the case of the stacked NPL ensembles as compared to the nonstacked NPLs lacking strong energy transfer. This study shows that it is essential to account for the effect of NPL stacking to understand their resulting PL emission properties.