Browsing by Subject "Representations"
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Item Open Access Cross-term-free time-frequency distribution reconstruction via lifted projections(Institute of Electrical and Electronics Engineers, 2015-01) Deprem, Z.; Çetin, A. EnisA crucial aspect of time-frequency (TF) analysis is the identification of separate components in a multicomponent signal. The Wigner-Ville distribution is the classical tool for representing such signals, but it suffers from cross-terms. Other methods, which are members of Cohen's class of distributions, also aim to remove the cross-terms by masking the ambiguity function (AF), but they result in reduced resolution. Most practical time-varying signals are in the form of weighted trajectories on the TF plane, and many others are sparse in nature. Therefore, in recent studies the problem is cast as TF distribution reconstruction using a subset of AF domain coefficients and sparsity assumption. Sparsity can be achieved by constraining or minimizing the l(1) norm. In this article, an l(1) minimization approach based on projections onto convex sets is proposed to obtain a high-resolution, cross-term-free TF distribution for a given signal. The new method does not require any parameter adjustment to obtain a solution. Experimental results are presented.Item Open Access Representations as a foreign policy analysis tool in Soviet-Turkish relations (1920-1946) : a critical constructivist approach(Bilkent University, 2006) Coş, KıvançThis thesis provides an account of Turkish Foreign Policy towards the Soviet Union in the inter-war and post-war eras from a critical constructivist point of view. It is argued that the radically different responses given by Turkish Foreign Policy makers to the contextually similar demands of the Soviet Union was allowed by the (re)construction of the representation of the Soviet Union in Turkish Foreign Policy discourse. It is further indicated that the Soviet ‘demands’ throughout the inter-war years did not alter the ‘sincere friend’ identity of the Soviet Union, while similar ‘demands’ in the post-war era entirely changed the identity of the Soviet Union to an ‘enemy’. Whereas the ‘sincere friend’ identity allowed for maintaining good relations with the Soviet Union, the ‘enemy’ identity allowed the move towards the United States as opposed to the Soviet Union.