Kurum Yazarı "Ünal, Hakkı Ulaş" Makale Koleksiyonu İçin Listeleme
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Characterization and Computation of Partial Synchronization Manifolds for Diffusive Delay-Coupled Systems
Steur, E.; Ünal, Hakkı Ulaş; van Leeuwen, C.; Michiels, W. (Siam Publications, 2016)Sometimes a network of dynamical systems shows a form of incomplete synchronization, characterized by synchronization of some but not all of its component systems. This type of incomplete synchronization is called partial ... -
Comparison of PI controllers designed for the delay model of TCP/AQM networks
Ünal, Hakkı Ulaş; Melchor-Aguilar, Daniel; Ustebay, Deniz; Niculescu, Silviu-Iulian; Özbay Hitay (Elsevier Science BV, 2013)One of the major problems of communication networks is congestion. In order to address this problem in TCP/IP networks, Active Queue Management (AQM) scheme is recommended. AQM aims to minimize the congestion by regulating ... -
Evaluating and Approximating FIR Filters: An Approach Based on Functions of Matrices
Michiels, Wim; Ünal, Hakkı Ulaş (IEEE-Inst Electrical Electronics Engineers Inc, 2015)Most of the controllers designed for systems with timedelays involve finite impulse response (FIR) filters in their structure, in particular prediction based controllers for systems with input/output delays. We present ... -
Performance and Robustness of Flow Controllers Designed Using Non-causal Uncertainty Blocks
Ünal, Hakkı Ulaş; İftar, Altuğ (Wiley, 2013)According to some recent results, use of non-causal uncertainty blocks may be advantageous in the robust controller design of systems with multiple uncertain time-delays. In this work, performance and robustness improvements ... -
Performance level and stability margins of an optimal H-infinity flow controller
Ünal, Hakkı Ulaş; İftar, Altuğ (SAGE Publications LTD, 2012)Flow controllers are needed to avoid congestion in different types of networks. The dynamics of such networks, however, can usually be represented by infinite-dimensional models, which are either based on partial-differential ... -
Prediction of partial synchronization in delay-coupled nonlinear oscillators, with application to Hindmarsh-Rose neurons
Ünal, Hakkı Ulaş; Michiels, Wim (IOP Publishing LTD, 2013)The full synchronization of coupled nonlinear oscillators has been widely studied. In this paper we investigate conditions for which partial synchronization of time-delayed diffusively coupled systems arises. The coupling ... -
Robust flow control in data-communication networks with multiple time-delays
Ünal, Hakkı Ulaş; Ataşlar-AyyIldız, Banu; İftar, Altuğ; Özbay Hitay (Wiley, 2010)Robust controller design for a flow control problem where uncertain multiple time-varying time-delays exist is considered. Although primarily data-communication networks are considered, the presented approach can also be ... -
A small gain theorem for systems with non-causal subsystems
Ünal, Hakkı Ulaş; İftar, Altuğ (Pergamon-Elsevier Science LTD, 2008)Small gain theorems are used to verify the stability of a feedback interconnection of causal stable systems. In this work, we extend the small gain condition to test the stability of a feedback interconnection of two stable ... -
Stable H-infinity controller design for systems with multiple input/output time-delays
Ünal, Hakkı Ulaş; İftar, Altuğ (Pergamon-Elsevier Science LTD, 2012)The stable H-infinity controller design problem is considered for multi-input-multi-output systems with multiple input/output time-delays. An algorithm is presented to solve this problem. The algorithm makes use of the ... -
Stable H-infinity flow controller design using approximation of FIR filters
Ünal, Hakkı Ulaş; İftar, Altuğ (SAGE Publications LTD, 2012)Stable flow controllers are usually preferred since, compared with unstable flow controllers, they are less sensitive to any modelling imperfections. H-infinity-optimal flow controllers involve finite impulse-response (FIR) ...