Browsing by Author "Olgun, U."

Now showing 1 - 3 of 3

Open Access
Gas generator pressure control in throttleable ducted rockets: a classical and adaptive control approach
(American Institute of Aeronautics and Astronautics (AIAA), 2015) Alan, Anıl; Yıldız, Yıldıray; Poyraz, Ü.; Olgun, U.
This paper describes the control of gas generator pressure in throttleable ducted rockets using nonlinear adaptive control as well as classical control approaches. Simulation results using the full nonlinear and time-varying dynamics of the gas generator are reported in both classical controller and adaptive controller cases. "Closed-loop Reference Model" structure is used together with the adaptive controller to improve transient response. Controllers are simulated to test their robustness by introducing uncertinities, disturbances and noise to the system. Cold Air Test Plant (CATP) is used as the test facility to compare the controllers and validate the results from simulations. Moreover, damping effect of CRM to oscillations in adaptive controller case is observed in CATP tests.
Open Access
On the capacity of printed planar rectangular patch antenna arrays in the MIMO channel: analysis and measurements
(IEEE, 2010) Tunc, C. A.; Olgun, U.; Ertürk, V. B.; Altintas, A.
Printed arrays of rectangular patch antennas are analyzed in terms of their MIMO performance using a full-wave channel model. These antennas are designed and manufactured in various array configurations, and their MIMO performance is measured in an indoor environment. Good agreement is achieved between the measurements and simulations performed using the full-wave channel model. Effects on the MIMO capacity of the mutual coupling and the electrical properties of the printed patches, such as the relative permittivity and thickness of the dielectric material, are explored.
Open Access
Particle swarm optimization of dipole arrays for superior MIMO capacity
(WILEY, 2009) Olgun, U.; Tunc, C. A.; Aktas, D.; Ertürk, V. B.; Altintas, A.
The particle swarm optimization (PSO) technique is employed to design MIMO arrays for superior capacity. A channel model based on the method of moments solution of the electric field integral equation is utilized with PSO for arrays of dipole elements. Freestanding and printed dipole arrays are analyzed and optimized. Their adaptive performance in the MIMO channel is compared. Numerical results in the form of mean capacity, including comparisons with genetic algorithm results and measurements, are given.