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Determination Of Oxygen And Nitrogen Impurities In Magnesium Metal By Vacuum Distillation And Icp-Oes Techniques, Javed Akhtar, S. K. Durrani, N. A. Chughtai, M. Munir, Bashir Mohammad
Determination Of Oxygen And Nitrogen Impurities In Magnesium Metal By Vacuum Distillation And Icp-Oes Techniques, Javed Akhtar, S. K. Durrani, N. A. Chughtai, M. Munir, Bashir Mohammad
Turkish Journal of Chemistry
Due to the various promising properties of magnesium as a structural material and certain other applications such as a reducing agent for refractory metals, magnesium metal has great commercial importance in many technical industries but the presence of oxygen and nitrogen impurities adversely affects its physico-chemical and mechanical properties. Therefore, the exact measurement of oxygen and nitrogen impurities is essential. The accuracy of analytical values of micro amounts of nitrogen and oxygen (\mu g.g^{-1} level) in magnesium metal has been measured indirectly. The conditions for the vacuum distillation (VD) method were optimized. Analysis of residue for magnesium content was studied …
Corrosion Of Reinforcing Steel In Concrete Immersed In Chloride Solution And The Effects Of Detergent Additions On Diffusion And Concrete Porosity, Hülya Kahyaoğlu, Mehmet Erbi̇l, Bi̇rgül Yazici, Ayşe Bahar Yilmaz
Corrosion Of Reinforcing Steel In Concrete Immersed In Chloride Solution And The Effects Of Detergent Additions On Diffusion And Concrete Porosity, Hülya Kahyaoğlu, Mehmet Erbi̇l, Bi̇rgül Yazici, Ayşe Bahar Yilmaz
Turkish Journal of Chemistry
In order to investigate the corrosion of reinforcing steel in concrete and the effects of chloride ions, oxygen diffusion and detergent additives of linear alkylbenzene (LAB) and linear alkylbenzene sulfonate (LAS), potentiokinetic experiments were carried out. Thus, by embedding steel electrodes into concrete specimens with a water/cement (W/C) ratio of 0.45, current-potential curves were obtained and the compressive strength of the specimens was measured. The electrochemical approach can be used to identify the effect of chloride on steel corrosion in concrete. It was found that the diffusion of chloride and oxygen through concrete and the reduction of oxygen on the …
Hybrid Sr Arq Scheme Using Trellis Coded Modulation For Point-To-Multipoint Communication Over Nonstationary Channels, Necmi̇ Taşpinar
Hybrid Sr Arq Scheme Using Trellis Coded Modulation For Point-To-Multipoint Communication Over Nonstationary Channels, Necmi̇ Taşpinar
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a type-I hybrid SR ARQ scheme using trellis coded modulation (TCM) for point-to-multipoint communication was analyzed on nonstationary broadcast channels where the channel bit error rate (BER) varies over time. A nonstationary channel is modelled as a two-state Markov chain. In the numerical calculations, it is found that, for a given p_{1} and \bar \varepsilon , the values of the average burst length \bar b have a very small influence on the throughput. Numerical results show that the throughput is better for values between 10 ^{-6} and 10 ^{-4}of average bit error rate \bar \varepsilon if the …
Stability Analysis Of A Closed-Loop Control For A Pulse Width Modulated Dc Motor Drive, Fatma Gürbüz, Eyüp Akpinar
Stability Analysis Of A Closed-Loop Control For A Pulse Width Modulated Dc Motor Drive, Fatma Gürbüz, Eyüp Akpinar
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, the effect of the variation of amplitude and the chopping period of a PWM signal on the stability of a closed-loop control for a DC motor drive is investigated. First, the entire system is formulated as a Linear Quadratic (LQ) tracker with output feedback [1]. Then, stability analysis for the varying amplitude and the varying chopping period is carried out by the methods of root locus and the Jury test. Finally, stability limits obtained from a root locus and Jury test are checked by the simulation of the system in MATLAB.
Cover And Contents
Turkish Journal of Electrical Engineering and Computer Sciences
No abstract provided.
Stimulated Polarization In \Bf Linbo_{3} And \Bf Ba_{2}Nanb_{5}O_{15} Crystals, Süleyman Çabuk, Amirullah Mamedov
Stimulated Polarization In \Bf Linbo_{3} And \Bf Ba_{2}Nanb_{5}O_{15} Crystals, Süleyman Çabuk, Amirullah Mamedov
Turkish Journal of Physics
Thermally Stimulated Conductivity (TSC) and thermoelectret state in LiNbO_{3} and Ba_{2}NaNb_{5}O_{15} were measured as a function of temperature and time in dark and under UV excitation at liquid nitrogen temperature. Effect of polarization and the other external influences on thermoelectret were investigated. The thermal activation energy levels of traps were determined from TSC measurements as well as parameters (electric field, temperature, etc.) which are necessary for characterizing thermoelectrets were obtained.
Microstructure And Critical Current Of Hot-Pressed Ybco Ceramics, Şadan Özcan, Tezer Firat, Engi̇n Özdaş
Microstructure And Critical Current Of Hot-Pressed Ybco Ceramics, Şadan Özcan, Tezer Firat, Engi̇n Özdaş
Turkish Journal of Physics
The effect of hot-pressing (HPing) on the densification and the superconducting properties of YBCO were investigated. The phases and microstructure were analysed by XRD and SEM and transport properties were studied by I-V and AC susceptibility measurements. Relative density up to 93% and critical current density of 509 A/cm^{2} at 77 K were achieved through uniaxial HPing at 800°C under 325 kg/cm^{2} pressure for 4 hours. HPing raised the J_{c} from 80 A/cm^{2} to 509 A/cm^{2}. These results and AC susceptibility measurements reveal that the weak links or pinning forces were improved by increasing HPing pressure.
Obituary Prof. Dr. Kâzım Ergi̇n [21 May 1915-24 November 2002] By, Tuncay Taymaz
Obituary Prof. Dr. Kâzım Ergi̇n [21 May 1915-24 November 2002] By, Tuncay Taymaz
Turkish Journal of Earth Sciences
No abstract provided.
The Dosimetric Verification Of Commercial Two- And Three- Dimensional Radiation Treatment Planning Systems, Ayhan Kiliç, Lütfi̇ Özkan, Kayihan Engi̇n
The Dosimetric Verification Of Commercial Two- And Three- Dimensional Radiation Treatment Planning Systems, Ayhan Kiliç, Lütfi̇ Özkan, Kayihan Engi̇n
Turkish Journal of Medical Sciences
For the quality assurance (QA) of radiation treatment planning systems (RTPSs) and planning computed tomography (CT), a simple cylindrical phantom was developed. The phantom was constructed by using materials and geometries appropriate for the routine clinic setups. A Siemens Somatom HiQ CT, two-dimensional (2D) and three-dimensional (3D) RTPS and a linear accelerator Siemens Mevatron MD2 were used in this study. The 2D and 3D RTPSs gave good results when compared to actual doses measured in the phantom. While the 3D system showed accuracy similar (-1.0% vs. -0.8%) to that of the 2D system for 6 MV and better accuracy (+1.4% …
Morphologic Comparison Of The Elastic Fibers Found In The Submucosal Layer In Different Portions Of The Stomach, Ahmet Kalaycioğlu, Mi̇that Keri̇m Arslan
Morphologic Comparison Of The Elastic Fibers Found In The Submucosal Layer In Different Portions Of The Stomach, Ahmet Kalaycioğlu, Mi̇that Keri̇m Arslan
Turkish Journal of Medical Sciences
This study was carried out on 30 human stomachs (from cadavers) obtained from different medical faculties. The elastic fibers in the submucosal layer in the pylorus, corpus and antrum were studied and compared in terms of their length, and density per unit area. The submucosal layer containing elastic fibers was longer and their densities per unit area were greater in the pylorus than those in the corpus and the antrum. Another feature of this study is the use of the vizopan microscop, which is used in the field of forestry engineering for measurements.
Plant Biotechnology I, Tissue Culture And Its Applications, Kemal Kazan
Plant Biotechnology I, Tissue Culture And Its Applications, Kemal Kazan
Turkish Journal of Botany
No abstract provided.
Experimental Investigation Of Temperature Effect On Refractive Index Of Dye Laser Liquids, Şeref Yaltkaya, Ramazan Aydin
Experimental Investigation Of Temperature Effect On Refractive Index Of Dye Laser Liquids, Şeref Yaltkaya, Ramazan Aydin
Turkish Journal of Physics
In this work, refractive index of selected dye laser solutions were measured by fiber optic sensor. The fiber optic probe was dipped into the liquids and according to Fresnel's Reflection Law, refractive index values were obtained at the wavelength of the laser utilized. The solutions consisted of Rhodamine 6G, Rhodamine B and Coumarin 481 dissolved in methanol, and ethylene glycol, respectively. Refractive index variations of the dye solutions and their solvents with temperature were measured and the refractive index temperature coefficient dn/dT were calculated at the wavelength of 780 nm.
A Personel Note, Leopold B. Felsen
A Personel Note, Leopold B. Felsen
Turkish Journal of Electrical Engineering and Computer Sciences
No abstract provided.
Iterative Solution Of Field Problems With A Varying Physical Parameter, Anton G. Tijhuis, Martijn C. Van Beurden, A. Peter M. Zwamborn
Iterative Solution Of Field Problems With A Varying Physical Parameter, Anton G. Tijhuis, Martijn C. Van Beurden, A. Peter M. Zwamborn
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, linear field problems with a varying physical parameter are solved with the conjugate-gradient FFT method and a dedicated extrapolation procedure for generating the initial estimate. The scheme is formulated and illustrated for two simple example problems. The importance of the choice of the stop criterion and the step size are demonstrated for the case of a straight thin-wire segment. A brief summary is given of the applications that have appeared in the open literature until now, and actual three-dimensional scattering problems for a rectangular conducting plate and an inhomogeneous, dispersive dielectric body are discussed. Finally, the case …
Network--Oriented Modeling Of Radiating Electromagnetic Structures, Peter Russer
Network--Oriented Modeling Of Radiating Electromagnetic Structures, Peter Russer
Turkish Journal of Electrical Engineering and Computer Sciences
The application of network-oriented modeling for radiating electromagnetic structures is investigated. Network methods are applied to the field problem using the segmentation technique and by specifying canonical Foster representations as compact models of reciprocal linear lossless electromagnetic structures. Connection between different subdomains is obtained via connection circuits exhibiting only ideal transformers. In the case of radiating structures, the complete structure is embedded into a sphere and the field outside the sphere is expanded into orthogonal spherical TM- and TE- waves. For each radiation mode a Cauer canonic circuit representation is given.
Novel Time Domain Radiowave Propagators For Wireless Communication Systems, Funda Akleman, M. O. Özyalçin, Levent Sevgi̇
Novel Time Domain Radiowave Propagators For Wireless Communication Systems, Funda Akleman, M. O. Özyalçin, Levent Sevgi̇
Turkish Journal of Electrical Engineering and Computer Sciences
In this study, novel time domain wave propagators are used in path loss calculations for macro and micro cell coverage planning in wireless communication systems. Both Transmission Line Matrix (TLM) and Finite-Difference Time-Domain (FDTD) based propagators, which were introduced recently and validated and verified on different canonical propagation scenarios, are used for this purpose. Examples are chosen both in rural and urban areas, where two propagators are compared with each other. Excellent agreement between the results obtained via two propagators is presented. The results presented here are very encouraging and these propagators are shown to be powerful tools for not …