M. Koseoglu

Investigation of the characteristics of dielectric barrier discharge in transition region

In the paper, we study the dielectric barrier discharge (DBD) occurring in a metal?insulator?gas?insulator?metal system. We encounter these kinds of discharges in ozonator-type reactors used in gas electrochemistry. The experiments are done in air medium when the gap width value is 580??m and the pressure is in the interval of 1?100?mbar. The schematic diagram of the experimental mechanism and the drawing methods of the characteristics are given, and it is determined that the barrier discharge has an impulse character. Experimentally, we determine that the voltage?current (v?i) and voltage?charge (v?q) characteristics of the discharge are linear for the case of (pl) (pl)cr, and these cases are explained theoretically. Furthermore, the determination method of the ratio of the fading voltage depending on the width of the steps of the experimental v?i characteristic to the inception voltage is given in this paper.

Calculation of electrical field of spherical and cylindrical gas voids in dielectrics by taking surface conductivity into consideration

Purpose – To determine the electrical field E1(t) in spherical and cylindrical gas voids existing in an insulator by considering surface conductivity of gas voids having an electrical permittivity of e1 and conductivity of γ1 for DC and AC situations.Design/methodology/approach – Analytical expressions satisfying Laplace equation for inside and outside of the cylindrical and spherical gas voids in an insulator located in an external electrical field having a definite time dependent character, have been derived by considering the surface conductivity of the gas void. The coefficients included by these analytical expressions have been determined by utilizing the continuity equation of the current on the surface of the voids.Findings – It has been demonstrated that the electrical field remains uniform in spherical and cylindrical gas voids when the surface conductivity of gas void has been considered. It has been determined that the contact charging process of different shaped particles has an exponential ch...

Design of an autonomous mobile robot based on ROS

In this paper, design of an autonomous mobile robot (AMR) adapted for robot operating system (ROS) is presented by considering both the hardware architecture and electronic communication protocols. Initially the purpose of the robot has been determined, and then the required components to construct the robot have been obtained. After mounting the electronic and mechanic hardware components on the platform, the required interconnections, data exchange system and software have been installed. Then the required tests have been run on the platform and some solutions methods have been proposed for the problems encountered during the tests. The results obtained and experience gained in the design of the platform have been quite satisfactory and will be a guiding light for future works.

Effect of plasma deposited thin carbon layer on dielectric characteristics of Au-PI-Au structures

In this study, dielectric properties of a virgin polyimide (PI) sample and tailored PI sample are investigated in a metal-insulator-metal (MIM) structure comparatively. In order to modify the dielectric properties of the tailored sample, plasma enhanced chemical vapor deposition (PECVD) method was used, and a thin a-C:H layer was deposited on the sample surface. Then dielectric permittivity, dielectric loss and ac conductivity characteristics, which were calculated according to the measured capacitance, loss factor and conductance values, were plotted versus frequency (0.1-100 kHz) and temperature (20-300°C). Also, SEM images and FTIR spectrum of the samples were presented and evaluated. Consequently, a-C: H layer and accompanying plasma polymer interactions during PECVD led to decrease the permittivity of the sample, and increase the thermal stability of the tailored sample relatively.

Space charge formation in non-cristalline polymers and GaSe by DBD In SF 6 medium

In this study, we investigate the formation mechanism of space charges in PI - polyimide, PTFE - polytetrafluoroethylene, PET - polyethylene terephtalate and GaSe(Sn)-GaSe doped with (0.05 at%) Sn which are exposed to dielectric barrier discharge (DBD) in SF6 medium. The expressions for the concentration of trapped electrons in materials, electrical field strength and total charge are derived by solving total current equation at stationary state. Space charges are determined experimentally by using thermally stimulated depolarization current (TSDC) method, and TSDC spectrums are illustrated for investigated materials.

Modeling and analysis of dielectric materials by using gradient-descent optimization method

This study presents a numerical method based on parallel RC equivalent circuit model fitting methodology for analysis and modeling of dielectric materials. The proposed method employs gradient-descent optimization method (GDOM) to estimate parallel RC equivalent circuit model from current waveforms by minimizing sum of squared difference (SSD) error. Estimation of parallel RC equivalent circuit parameters from measured current waveforms provides a useful tool for identification, simulation and analysis of dielectric materials. Moreover, applications of the proposed method for time and frequency analyses of dielectric materials are demonstrated numerically. Numerical simulations were presented to discuss efficiency of the proposed method for modeling, analysis and monitoring of insulator materials.

The Changes in Electrical and Interfacial Properties of Polyimide Exposed to Dielectric Barrier Discharge in SF6 Medium

The formation mechanism of space charges in polyimide (PI) which was exposed to dielectric barrier discharge (DBD) in SF6 medium and the effects of the space charges on interfacial and electrical properties of PI were investigated. The variation of normalized surface charge density on PI sample was calculated and illustrated for different DBD exposure times. The surface potential was measured to determine the effect of the space charges on the sample. Then, the contact angle values were measured to obtain the relation between the surface energy and the surface charge density. The expressions for the total charge and the concentration of trapped electrons were derived by using Poisson and continuity equations at stationary state. The space charges were determined experimentally by using thermally stimulated depolarization current (TSDC) method. Also, SEM image and FTIR spectrum of virgin and treated samples were presented to observe the structural variations. It was seen that the approach for the formation mechanism of the space charges agreed with the experimental data. However, it was concluded particularly for the short-time DBD treatments that the space charges accumulated in the sample should be considered besides the effects of surface functionalization in the determination of the surface energy.