Yazar "Alisoy, H. Z." seçeneğine göre listele
Listeleniyor 1 - 8 / 8
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe An analysis of corona field charging kinetics for polydisperse aerosol particles by considering concentration and mobility(Iop Publishing Ltd, 2010) Alisoy, H. Z.; Alagoz, B. B.; Alisoy, G. H.In this paper, the kinetics of the charging process of polydisperse aerosol particles in a unipolar corona field is analysed and the effects of the particle concentration and particle mobility on the charging kinetics are investigated theoretically. An equation for time constant is derived to evaluate charging time of the particles.Öğe The analysis of the charge on a cylindrical dielectric particle in unipolar corona field(Elsevier Science Bv, 2011) Koseoglu, M.; Alisoy, H. Z.In this study, a nonlinear integro-differential equation is derived to express the charging kinetics of stationary and rotational cylindrical dielectric particle in unipolar corona field. An algorithm is developed to solve the derived equation numerically by using Euler method. The variation of charge on the dielectric cylindrical particle is presented and evaluated by considering the variable parameters of the particle, medium and field. Assessments of the numerical results demonstrate that the limit charge value on stationary cylindrical dielectric particle during the charging process in unipolar corona field is less in comparison with the rotational cylindrical particle in identical conditions. Also this is an important factor for electron ion technology in the aspect of charging kinetic problems. (C) 2011 Elsevier B.V. All rights reserved.Öğe An FDTD based numerical analysis of microwave propagation properties in a skin-fat tissue layers(Elsevier Gmbh, 2013) Alisoy, H. Z.; Us, S. Barlaz; Alagoz, B. B.This study theoretically investigates wave propagation properties at the interface of air-skin-fat tissues for a microwave frequency of 6.8 GHz. For this proposes, propagation of the microwaves in a biological tissue model of skin-fat are numerically analyzed by using FDTD method for the transverse magnetic (TM) mode of 2D-Maxwell's equations. These analyses are conducted for various point source placements such as none-contacting, embedded to skin and embedded to fat configurations. Electric field intensity and SAR distribution across the air-skin-fat tissue layers are revealed. The energy penetration and absorption degrees of planar skin-fat tissue layers are discussed in a physical origin. The large electrical impedance mismatches between the tissue layers result in reflection of microwaves from the interface of layers. Skin layer exhibits a considerable wave reflection property due to the high reflection coefficient at air-skin and skin-fat interfaces. (C) 2013 Elsevier GmbH. All rights reserved.Öğe An Investigation of Ionic Flows in a Sphere-Plate Electrode Gap(Iop Publishing Ltd, 2013) Alisoy, H. Z.; Alagoz, S.; Alisoy, G. T.; Alagoz, B. B.This paper presents analyses of ion flow characteristics and ion discharge pulses in a sphere-ground plate electrode system. As a result of variation in electric field intensity in the electrode gap, the ion flows towards electrodes generate non-uniform discharging pulses. Inspection of these pulses provides useful information on ionic stream kinetics, the effective thickness of ion cover around electrodes, and the timing of ion clouds discharge pulse sequences. A finite difference time domain (FDTD) based space-charge motion simulation is used for the numerical analysis of the spatio-temporal development of ionic flows following the first Townsend avalanche, and the simulation results demonstrate expansion of the positive ion flow and compression of the negative ion flow, which results in non-uniform discharge pulse characteristics.Öğe Modeling and analysis of dielectric materials by using gradient-descent optimization method(World Scientific Publ Co Pte Ltd, 2017) Alagoz, B. B.; Alisoy, H. Z.; Koseoglu, M.; Alagoz, S.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.Öğe A numerical method for the analysis of polydisperse aerosol particles charging in a coaxial electrode system(Elsevier Science Bv, 2012) Alisoy, H. Z.; Alagoz, S.; Alisoy, G. H.; Alagoz, B. B.In this paper, charging kinetics of polydisperse aerosol particles in a corona field of a coaxial electrode system is numerically analyzed for a logarithmic normal distribution of aerosol particle size. The particle charging and the particle current are calculated by using a charging model considering ion concentration and particle mobility. Particle charging profiles under varying ion density and electrical field intensity distributions of the charging chamber were revealed. A low charging profile in the transition region of bipolar corona field was demonstrated in the simulation results. (C) 2011 Elsevier B.V. All rights reserved.Öğe Space Charge Formation In Non-cristalline Polymers And GaSe By DBD In SF6 Medium(Ieee, 2008) Alisoy, H. Z.; Yeroglu, C.; Koseoglu, M.In this study, we investigate the formation mechanism of space charges in PI-Polyimide, PTFE-Polytetrafluoroethylene, PET - Polyethylene Terephtalate and GaSe(Sn) - GaSe dopped with (0.05at%) 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.Öğe Spatio-spectral analyses of electromagnetic wave energy absorption and heating effect(Elsevier Gmbh, 2014) Alisoy, H. Z.; Alagoz, B. B.; Us, S. Barlaz; Deniz, F. N.; Alagoz, S.This study presents a theoretical analysis method to calculate electromagnetic (EM) wave power absorption spectrum of materials by using attenuation coefficients. The heating effect of EM waves is modeled to analyze spectral distribution of temperature rises inside material body as a result of EM wave power absorption. These analyses are very useful for the investigation of electromagnetic wave-material interaction on the bases of electro-physical material parameters (permittivity, permeability and conductivity). An illustrative analysis of spatio-spectral distribution of EM wave energy absorption and resulting heating effect were conducted for muscle tissues and the results are discussed. (C) 2014 Elsevier GmbH. All rights reserved.
