Browsing by Subject "Spatio-temporal analysis"

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Open Access
Deepfake detection through motion magnification inspired feature manipulation
(2022-09) Mirzayev, Aydamir
Synthetically generated media content poses a significant threat to information security in the online domain. Manipulated videos and images of celebrities, politicians, and ordinary citizens, if aimed at misrepresentation, and defamation can cause significant damage to one's reputation. Early detection of such content is crucial to timely alleviation of further spread of questionable information. In the past years, a significant number of deepfake detection frameworks have proposed to utilize motion magnification as a preprocessing step aimed at revealing transitional inconsistencies relevant to the prediction outcome. However, such an approach is sub-optimal since often utilized motion manipulation approaches are optimized for a limited set of controlled motions and display significant visual artifacts when used outside of their domain. To this end, rather than apply motion magnification as a separate processing step, we propose to test trainable motion magnification-inspired feature manipulation units as an addition to a convolutional-LSTM classification network. In our approach, we aim to take the first step at understanding the use of magnification-like architectures in the task of video classification rather than aim at full integration. We test out results on the Celeb-DF dataset which is composed of more than five thousand synthetically generated videos generated using DeepFakes fake generation method. We treat manipulation unit as another network layer and test the performance of the network both with and without it. To ensure the consistency of our results we perform multiple experiments with the same configurations and report the average accuracy. In our experiments we observe an average 3% jump accuracy when the feature manipulation unit is incorporated into the network.
Open Access
Spatio-temporal analysis of throughput for single-hop CSMA networks
(Institute of Electrical and Electronics Engineers Inc., 2014) Koseoglu, M.; Karasan, E.
Throughput model for non-persistent CSMA networks which was proposed by Kleinrock and Tobagi has been widely used, although it provides a loose lower bound when nodes are distributed in a large area because the analysis assumes that the propagation delay between each pair of users equals to the largest propagation delay in the network. We present a throughput analysis which considers the spatial distribution of nodes. We obtain a simple throughput expression which predicts throughput with an 8% maximum error whereas the earlier model results in a 44% error when the maximum propagation delay equals to the packet transmission time. © 2014 IEEE.