Browsing by Subject "Source localization"
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Item Open Access ERP source reconstruction by using Particle Swarm Optimization(IEEE, 2009) Alp, Yaşar Kemal; Arıkan, Orhan; Karakaş, S.Localization of the sources of Event Related Potentials (ERP) is a challenging inverse problem, especially to resolve sources of neural activity occurring simultaneously. By using an effective dipole source model, we propose a new technique for accurate source localization of ERP signals. The parameters of the dipole ERP sources are optimally chosen by using Particle Swarm Optimization technique. Obtained results on synthetic data sets show that proposed method well localizes the dipoles on their actual locations. On real data sets, the fit error between the actual and reconstructed data is successfully reduced to noise level by localizing a few dipoles in the brain.Item Open Access Wideband maximum likelihood direction finding and signal parameter estimation by using the tree-structured EM algorithm(Institute of Electrical and Electronics Engineers, 1999-01) Çadallı, N.; Arıkan, OrhanThe expectation maximization (EM) algorithm is presented for the case of estimating direction of arrivals of unknown deterministic wideband signals. Alternative regularized least squares estimation techniques for the required signal estimation and a tree structure for the data mapping in the EM algorithm are proposed. Extensive simulation results are presented for comparison of the proposed algorithms with the conventional EM approach and the current high-resolution methods of wideband direction finding.