Osman Cerezci

Elman's recurrent neural networks using resilient back propagation for harmonic detection

In this study, the method to apply the Elmans recurrent neural networks using resilient back propagation for harmonic detection is described. The feed forward neural networks are also used for comparison. The distorted wave including 5th, 7th, 11th, 13th harmonics were simulated and used for training of the neural networks. The distorted wave including up to 25th harmonics were prepared for testing of the neural networks. Elmans recurrent and feed forward neural networks were used to recognize each harmonic. The results obtained using Elmans recurrent neural networks are better than the results values obtained using the feed forward neural networks for resilient back propagation.

Analysis on trending electromagnetic exposure levels at homes and proximity next to base stations along three years in a city

AbstractElectromagnetic field exposure levels of people living in the closest houses to the GSM transmitting antennas were investigated in a city between 2010 and 2012. At the end of 3-year period, trend of the electromagnetic exposure levels was determined especially for indoor/outdoor environments near the base station antennas. Because of increasing number of base stations by years and changing of the technology, it is determined that average electromagnetic exposure values in the city increased in a certain extent each year. Total and frequency selective measurements were performed in indoor/outdoor places. The results were compared by International ICNIRP limits. In addition, possibility of the compliance with some European countries which have applied low limit values are discussed to minimize involuntary exposure to electromagnetic fields at indoor/outdoor environments. Consequently, a suggestion is made and discussed for obtaining relatively homogeneous distribution of electromagnetic field exposu...

Theoretical and experimental study of EM fields and shielding effectiveness due to high voltage transmission lines

In this study, the EM fields produced by high power 3-phase transmission lines are investigated. The dependence of the magnetic field with respect to vertical and horizontal distances from the transmission lines are illustrated and the minimum distance from the lines for human safety is specified according to ICNIRP standards. In addition, a quasi-static examination to the magnetic shielding of several enclosures are performed. In the analysis, the integral form of Maxwells equations with boundary conditions are used to derive the shielding effectiveness (SE) equations. An experiment is carried out to verify the validity of the theory developed for magnetic fields of transmission lines and the SE provided by the building. An excellent agreement is obtained for experimental and theoretical results.

Image thresholding using measures of fuzziness

In image analysis, image thresholding which is used for separating the object from the background is one of the most common application. For the preprocessing purposes of an image, thresholding is a necessary tool. Here, a new method based on minimizing measures of fuzziness is presented. Every pixel in the image and the averaged image have a membership value. Using these membership values entropy measures of fuzziness of image set and averaged image set are calculated. Then, threshold is founded by optimally minimizing calculated measures. The experimental results indicated that the new method has good performance but takes a long time in averaging.

UHF ray tracing propagation model for corridors

Wave propagation for rectangular corridors is studied. Ray theory and uniform theory of diffraction (UTD) were combined to predict wave strength. The model was checked doing measurements at 1 GHz. The results show good agreement between theory and measurements for different locations. Since some parts of corridors have different properties (e.g. constructed by glass, wood and/or cement, etc.). We prepared a useful database considering all possible effects at any point of reflection

Calculation of leakage through apertures on coaxial cable braided screens

In this paper the more accurate calculation of the direct leakage of magnetic field through the diamond shaped holes is shown by using an early work on the planar mesh surfaces. The exact geometry of the diamond shaped holes is taken into account. The details of the calculation are shown step by step.

Coupling on Complex Platforms: A Comparison Between MOM and MOM/UTD Hybrid Method

In this paper, the analysis of mutual coupling between monopole antennas mounted on the aircraft at UHF band is presented. The method of moments (MoM) and hybridized MoM with uniform geometrical theory of diffraction (UTD) method (MoM/UTD) are used to calculate the coupling in 225-400 MHz frequency range. Numerical results with MoM and MoM/UTD are performed and the reliability of these methods is discussed based on the measurement results

Transfer impedance of contacting double braided coaxial screens

In this paper, the transfer impedance of the double braided screens in contact is investigated. The effect of the interlayer inductance between the both braid layers in contact is calculated and verified by experiments. The Krugels approximation for the mutual inductance calculation of double braided coaxial cable screen in contact is modified. The measured values shows that Krugels approximation is not so correct therefore, a new model is developed for calculation that is more correct. Best fitting of the equivalent average distance value between the both braid layers are performed via measured values of several coaxial cable screens.

Measurement of electromagnetic radiation around wind turbines

The number of wind energy plants in energy production is rapidly increasing in many countries of the world. In recent years, as an alternative energy source, it has been observed that wind energy installations have been established in various regions of our country. Wind turbines are sometimes discussed with the concern that the electromagnetic fields around them can cause health problems. In this study, ELF electromagnetic field levels are given, obtained around the 16.2 km long transmission line which enables the energy generated in 50 wind energy energy central turbines operating in Izmir-Karaburun locality to be transported to the 380kV Karaburun Havza GIS TM transformer center. The results are obtained in magnetic field and electric field. And they are evaluated for electromagnetic pollution in terms of environment and human health.

Electromagnetic radiation interaction and pollution measurements

Electromagnetic waves caused from base stations, which are rapidly increasing due to the opportunities provided by modern technology, create an undesired effective electromagnetic pollution in the environment. Mobile phones, as an important electromagnetic radiation source in the human body, are deliberately preferred devices for their use. However, those who live near base stations are exposed to electromagnetic radiation outside of personal preference and often are unaware of this effect. Especially, in districts with high populations such as Kadıköy, possible negative effects should be systematically examined by independent measurement institutions. In this study, the results of the 3-year project entitled “Determination of Electromagnetic Radiation from Base Stations at Istanbul Kadıköy and Determination of Exposure Levels” are discussed in comparison with national and international limits.