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Kayseri, Turkey

Bozer A.,Nuh Naci Yazgan University | Altay G.,Bogazici University
Structural Control and Health Monitoring | Year: 2013

The optimization of tuned mass damper (TMD) involves the attachment of a damper to a TMD unit. Although this supplementary damping renders TMD to be operational under broad bandwidth inputs (i.e., wind excitation), it also considerably decreases the efficiency. In this paper, an alternative approach is suggested to eliminate the requirement for supplementary damping, hence to utilize TMD in full efficiency. For this purpose, combined structure/undamped TMD system is equipped with an active controller to track the response of an oscillator with natural frequency set to the operating frequency of the TMD unit. In this case, a proposed controller does not aim returning a system to its zero state; instead, it supports the TMD unit to suppress vibration effectively. This tracking type controller is formulized by both linear quadratic regulator, and H∞ control schemes, and control performances of each system are evaluated through numerical simulations. © 2011 John Wiley & Sons, Ltd. Source


Guney K.,Nuh Naci Yazgan University | Onay M.,Erciyes University
Microwave and Optical Technology Letters | Year: 2011

In this article, we propose a method based on the bees algorithm (BA) to synthesize thinned linear antenna arrays with low sidelobe level.The BA is an optimization algorithm inspired by the behavior of the honey bees to find the optimal way of harvesting food resources around the hive. Several examples with different thinning percentages are given to show the effectiveness of the proposed method. The results of BA are compared with the results of real coded genetic algorithm, ant colony optimization, and iterative Fourier technique. © 2011 Wiley Periodicals, Inc. Source


Yamacli S.,Nuh Naci Yazgan University
Computational Materials Science | Year: 2014

Investigation of the conductance properties of metal-graphene contacts is essential for the future nanoelectronics technology. In this study, we focus on the conductance mechanism and the voltage-dependent transport properties of both p-type and n-type graphene-metal contacts. Copper and gold are chosen as the contact metal for n-type and p-type doped graphene-metal interface, respectively. Utilizing first principles quantum mechanical calculations with density functional theory in conjunction with Green's function formalism, transmission spectra of graphene-metal contacts and the voltage-dependent variations of the current and the resistance are obtained. Finally, it is shown that obtained resistance-voltage behaviours of graphene-metal contacts are in consistent with the results reported in the literature and the voltage-dependency of the contact resistance has to be taken into consideration for the nanoscale circuit design process. © 2013 Elsevier B.V. All rights reserved. Source


Yamacli S.,Nuh Naci Yazgan University
Computational Materials Science | Year: 2014

Considering that the current microelectronics technology is built upon silicon, various nanoscale silicon structures are being investigated. In this study, voltage-dependent transmission characteristics of short silicon nanotubes (SiNTs) are investigated using first-principles methods. Density functional theory in conjunction with non-equilibrium Green's function formalism is utilized to simulate metallic (5, 5) and (8, 8) SiNTs in order to obtain their current-voltage characteristics. The variation of the SiNT resistance with the applied voltage is also given and discussed together with the change in the transmission spectra. It is shown that current-voltage characteristics of short metallic SiNTs show nonlinear behaviour due to the changes in their transmission spectra. Obtained results and characteristics have implications on nanoscale SiNT interconnect design. © 2014 Elsevier B.V. All rights reserved. Source


Saatci M.,Nuh Naci Yazgan University | Dumrul Y.,Usak University
International Journal of Energy Economics and Policy | Year: 2013

In this study the aim was to investigate empirically the role of energy consumption in economic growth for the Turkish economy. The data used include annual energy consumption and economic growth series from 1960 to 2008. We used aggregate as well as various disaggregate data on energy consumption, including, oil, electricity, coal and renewable energy. Our contribution is that we take a structural breaks modeling approach in this paper. In the literature, the Kejriwal cointegration test has not been applied to date. The main conclusion of the study was that Turkey's energy consumption and economic growth has a positive relationship varying quantity with structural breaks. Source

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