Yazar "Ünal, Hakkı Ulaş" için listeleme
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Algorithms and software for approximating and evaluating fir filters
Michiels, Wim; Ünal, Hakkı Ulaş (Institute of Electrical and Electronics Engineers Inc., 2014)The controllers designed for time-delays systems often involve finite impulse response (FIR) filters, in particular prediction based controllers for systems with input/output delays. We present algorithms and software to ... -
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 ... -
Comparing PI controllers for delay models of TCP/AQM networks
Ünal, Hakkı Ulaş; Melchor-Aguilar, D.; Üstebay, D.; Niculescu, S. -I.; Özbay Hitay (IFAC Secretariat, 2010)In this paper, ns-2 simulations and related comparisons of four different PI controllers designed for TCP/AQM networks will be presented. The simulations are performed for various scenarios -
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 ... -
Decentralized control of time-delay systems
Erol, Hüseyin Ersin (Anadolu Üniversitesi, 2014)Bu tezde, zaman gecikmeli sistemler için merkezi olmayan denetleyici tasarımı ele alınmıştır. Doğrusal zamandan bağımsız (DZB) zaman gecikmeli bir sistemin merkezi olmayan zaman gecikmeli denetleyiciler ile kararlı ... -
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 ... -
Further Remarks on Delay Dynamics in Oregonator Models
Ünal, Hakkı Ulaş; Boussaada, İslam; Niculescu, Silviu-Iulian (IEEE, 2016)Motivated by the fact that molecules reacting through some biological channels may need some time-lag due transcription and translation processes, this note is devoted to the study of stability properties of a delayed ... -
Further remarks on the effect of multiple spectral values on the dynamics of time-delay systems. Application to the control of a mechanical system
Boussaada, İslam; Tliba, Sami; Niculescu, Silviu-Iulian; Ünal, Hakkı Ulaş; Vyhlidal, Tomas (Elsevier Science Inc, 2018)A question of ongoing interest for linear Time-delay systems is to determine conditions on the equation parameters that guarantee the exponential stability of solutions. In recent works a new interesting property of ... -
H? controller design for uncertain multiple-time-delay systems
Ünal, Hakkı Ulaş (Anadolu Üniversitesi, 2010)In this dissertation, H? controller design for systems with multiple uncertain time-delays is studied. In the H? controller design for these systems, since the nominal time-delays are taken outside the generalized plant, ... -
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 ... -
Prediction of partially synchronous regimes of delay-coupled nonlinear oscillators?
Ünal, Hakkı Ulaş; Michiels, W. (2013)We present an approach which allows to accurately predict both the occurrence and type of partially synchronous regimes of delay-coupled non-linear oscillators. Unlike the conventional approach, we build on an analysis of ... -
Robust control design for time-delay systems using non-causal uncertainty blocks
Ünal, Hakkı Ulaş; İftar, Altuğ (Institute of Electrical and Electronics Engineers Inc., 2014)Robust controller design problem for time-delay systems is considered. Both the time-delays, which may appear at the inputs and/or outputs of the plant, and the finite-dimensional part of the plant are assumed to be subject ... -
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) ... -
Stable H? flow controller design
Ünal, Hakkı Ulaş; İftar, Altuğ (2009)Stable H? controller design, for a flow control problem which involves multiple time-delays, is considered. An algorithm, which produces a stable controller apart from the integral action, is developed utilizing a rational ... -
Strong stabilization of time-delay systems
Ünal, Hakkı Ulaş; İftar, Altuğ (IFAC Secretariat, 2012)Stable controllers are required due to modelling imperfections and for better performance achievements. As is well known, a stable stabilizing controller for a given real-rational plant exists if and only if the plant ...
