2018 Cilt 23 Sayı 2

Permanent URI for this collectionhttps://hdl.handle.net/11452/12466

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Browsing by Department "Elektrik Elektronik Mühendisliği Bölümü"

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    The combined impact of SRS and FWM phenomena on the downlink channel performance of DWDM-GPON systems
    (Uludağ Üniversitesi, 2018-05-23) Ibrahim, Faisal Ibrahim Mohamed; Karlık, Sait Eser; Mühendislik Fakültesi; Elektrik Elektronik Mühendisliği Bölümü
    In this paper the combined impact of stimulated Raman scattering (SRS) and four-wave mixing (FWM) on the downlink channel performance of dense wavelength division multiplexed-gigabit passive optical networks (DWDM-GPONs) has been compared with the single impact of FWM via signal-tocrosstalk ratio (SXR) simulations performed on center downlink channels of 7-, 15- and 31-channel DWDM-GPON systems. Simulation results show that SRS compensates negative impacts of FWM and compensation significance enhances with increasing channel numbers and channel spacing values. At high channel spacing values of 50 GHz and 100 GHz, variation of SXR can display a strong oscillatory behavior in very short channel length variations of 0.5 km. The combined impact of SRS and FWM enhances the maximum oscillation amplitude of SXR variation with respect to the single impact of FWM at those channel spacing values. It has been observed that Raman gain exhibits an approximately linear variation with channel input powers in 0.1-5 mW range and it increases with increasing fiber lengths, channel spacing values and channel numbers. Results of this research emphasize the significant difference between the combined impact of SRS and FWM and the single impact of FWM on DWDM-GPON systems and give important hints for current DWDM-GPON implementations.
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    Stability analysis of a class of Takagi-Sugeno Fuzzy Cohen-Grossberg neural networks with time delays
    (Uludağ Üniversitesi, 2018-05-15) Özcan, Neyir; Barış, Samet; Fen Bilimleri Enstitüsü; Elektrik Elektronik Mühendisliği Bölümü
    This paper deals with the problem of the global asymptotic stability of the class of TakagiSugeno Fuzzy Cohen-Grossberg neural networks with multiple time delays. By constructing a suitable fuzzy Lyapunov functional, we present a new delay-independent sufficient condition for the global asymptotic stability of the equilibrium point for delayed Takagi-Sugeno Fuzzy Cohen-Grossberg neural networks with respect to the Lipschitz activation functions. The obtained condition simply relies on the network parameters of the neural system. Therefore, the equilibrium and stability properties of the neural network model considered in this paper can be easily verified by exploiting some basic properties of some certain classes of matrices.