Sait Eser Karlik

A novel liquid level detection method and its implementation

There are various methods and implementations for level detection. Optical methods display a rapid growth among these with their high sensitivities and low costs. In this paper, we propose a new method that uses reciprocally placed LEDs and phototransistors whose optical axes are shifted according to each other. Shifting distance is determined by the direction of the change in the fluid level. The minimum value of the shifting distance depends on dimensions of the LED and the phototransistor. The advantage of this method is that optical properties of the liquid do not have significant effects on level detection phenomenon. Our method can be used in detecting levels of water and inflammable fluids (gasoline, fuel oil, alcohol, etc.).

Analysis of interactions between node induced crosstalk and fiber nonlinearities in optical metropolitan area networks

The problems that occur at the nodes of a metropolitan area network (MAN) can interact with optical fiber nonlinearities. In this paper, impacts of such interactions, in particular the one between crosstalks occurring at the optical add/drop multiplexers (OADMs) of metropolitan network nodes and optical fiber nonlinearities, on transmission performances of optical fiber systems are investigated. The optical fiber systems are a non-zero dispersion shifted fiber (NZDF) system and a standard single mode fiber (SMF) system where dispersion compensating fiber (DCF) is used for dispersion management, shortly a SMF+DCF system. Significant impairments on transmission performances are observed in simulations. The results show that such interactions should be carefully considered during the design of metropolitan WDM networks.

Comparative analysis of the effect of optical fiber spin profiles on polarization mode dispersion

In long-haul and high-bit-rate optical fiber transmission systems Polarization Mode Dispersion (PMD) is one of the main reasons for pulse broadening. In order to reduce PMD-based problems, current studies rely on novel PMD compensators and low-PMD fiber productions. In this paper, after describing theoretical information about PMD and optical fiber spinning process, different spin profiles are examined. Comparative analysis of spin profiles is made and spin parameters giving successful results for low-PMD fibers are obtained for each spin profile. Simulation results show that for fixed spin period of 1 m 2.76 turns/m and 5.64 turns/m are proper spin amplitude values for sinusoidal and amplitude modulated (AM) spin profiles, respectively, while 3.40 turns/m and 3.75 turns/m are recommended spin amplitudes for triangular and trapezoidal spin profiles, respectively. Using these parameters, related spin profiles give better differential group delay (DGD) reduction results individually.

Optical fiber distributed sensing of temperature, thermal strain and thermo-mechanical force formations on OPGW cables under wind effects

Optical ground wire (OPGW) is generally used to protect the phase conductors of the overhead power cables from high discharge currents due to lightning strikes and instantaneous current increase due to short-circuits or breakdowns as well as to provide data transmission for telecommunication purposes. OPGW cables are exposed to effects of environmental factors such as wind, rain, humidity and snow as well as cooling/heating effects of short-circuits and instantaneous current increases occurring on the phase conductor. When the OPGW cable is exposed to those effects, deformations occur on the cable insulation in time. In this study, using Raman effect based optical fiber distributed temperature sensing (DTS) method, temperature and thermal strain variations occurring along the OPGW cable due to environmental conditions, in particular wind speed and wind direction, have been analyzed and simulations have been performed. Furthermore, thermo-mechanical forces occurring on the OPGW cable have been expressed as a function of temperature change and Young modulus variations. Temperature and thermal strain dependencies of thermo-mechanical forces have also been derived. Using results of the theoretical analysis, simulations of thermo-mechanical force variations along the sensing fiber have also been performed considering the wind effect. The simulation model has been built up for central loose tube type OPGW cable containing single mode optical fiber operating at 1550 nm. For wind speed variations between 5.3 m/s and 10.3 m/s, minimum temperature detected on the cable varies between 26.86 °C and 22.41 °C, respectively, minimum thermal strain varies between 184 με and 64.67 με, respectively. Simulation results show that temperature sensitivities of thermo-mechanical forces are 26 times greater than thermal strain sensitivities.

A Novel Protocol Proposal for Integratıon of SIP Based Telephony Services To IPTV System

In this study, a novel architecture that will provide integration of session initiation protocol (SIP) based call server telephony services with IPTV system has been proposed, a novel protocol (Independent Notification Protocol) has been designed for this aim and advantages of the developed architecture have been analyzed. The proposed architecture and supporting protocols eliminate the need for a middleware layer in the notification architecture. Therefore, one layer is reduced from the notification architecture and dependence to a special middleware finishes, i.e. the notification architecture can be built up with any kind of middleware layer. Test results for the proposed architecture and the protocol have showed that notification bandwidth reduces to 10 % of that of conventional notification architecture and the proposed architecture works successfully.