Hülya Yilmaz

Dielectric properties and electric conductivity of talc and doped talc

The dielectric properties of a MgO and Mg(NO3)2 doped and undoped talc are measured as a function of the frequency range 260 kHz-40 MHz. The ´, tan and ac values are given as a function of the firing temperature for a 5.0 MHz constant frequency. In this study the effects of an impurity and the firing temperature on the dielectric properties are also discussed.

Excess properties of methanol-water binary system at various temperatures

SummaryIn this study the viscosities of binary mixtures of methanol and water have been measured in the temperatures ranging from 15 to 45°C. The structural changes occurring as a consequence of molecular interactions in the solutions have been discussed in detail. Nevertheless, it would be of interest to see whether the information obtained from viscosity studies can be corroborated with that obtained from dielectric-constant data. With this aim, the present study on the dielectric behaviour of methanol-water binary solutions has been undertaken. The static dielectric constants, densities and refractive indices have been also measured on the methanol-water mixtures expressed by the mole fraction of methanol (0<x2<1). Excess dielectric constants, excess volumes, excess viscosities and excess Gibbs energies of activation of the viscous flow and Kirkwood correlation factors have been evaluated using experimental results since these calculations may lead to conclusions concerning the deviation of the system from an ideal-mixture behaviour.

The effect of electrode shape, gap and moisture on dielectric breakdown of transformer oil

Dielectric liquids have been used as an insulator for more than a century. The initiation of electrical breakdown and the role various types of effects have on it have been investigated for the last 30-40 years. In this study the variation of the breakdown voltage of transformer oil chosen as a liquid insulator with both electrode shape and gap has been examined. For this purpose, homogeneous and inhomogeneous fields with 5 pairs of electrodes which are at different standards have been created. The effects on electrical breakdown voltage of moisture content in the oil have also been investigated.

İlköğretim Öğrencilerinin Fen-Teknoloji-Tasarım Süreci İle İlgili Becerilerinin Geliştirilmesi Üzerine Bir Eğitim Modülü Uygulaması

Bu calismada ogrencilerin teknoloji ve tasarim konusundaki bilgilerini artirmak ve fen ve teknoloji okuryazari olmalarina katkida bulunmak amaciyla hazirlanan bir egitim modulu 4., 5. ve 6. sinif ogrencilerinin olusturdugu 88 kisilik bir gruba uygulanmistir. Boston Universitesi Bilim Muzesi tarafindan (Museum of Science) gelistirilen “Cocuklar Icin Muhendislik ve Teknoloji Dersleri” (Engineering and Technology Lessons for Children) isimli egitim modulu, “kuvvet” konusu ele alinarak uygulanmistir. Muhendislik Tutum Olcegi, Teknoloji Nedir? ve Muhendislik Nedir? olcekleri veri toplama araci olarak uygulama oncesi ve sonrasinda uygulanmistir. Verilerin analizi sonucunda; egitim oncesinden sonrasina tutum puanlarinin ortalamalari arasinda anlamli farkin oldugu gozlemlenmistir. Gruplara bakildiginda, 4. sinif ogrencilerinin bilim ve muhendislikle ilgili tutumlarinda artis gozlenmemekle birlikte 5. ve 6. siniflarda artis oldugu gorulmustur. Teknoloji Nedir? olcegi analiz edildiginde 4, 5 ve 6.sinif ogrencilerinin teknoloji ile ilgili bilgi duzeylerinde anlamli yonde bir artis oldugu tespit edilmistir. Muhendislik Nedir? olcegi veri analizi sonucunda her sinif icin puan ortalamalari artmis ve 5. ve 6. siniflarda bu artis anlamli duzeyde olmustur. Calisma sonucunda, ilkokul programlarina muhendislikle ilgili uygulamalarin entegre edilmesi konusunda onerilerde bulunulmustur.

Investigation of loss factors of some alcohols

The behavior and strength of dielectrics used in electric circuits are investigated with the method of loss factor and Q-factor. The purpose is to calculate the tq delta loss factors of certain liquids. Two liquids of aliphatic structure and one of aromatic structure were dissolved in nonpolar benzene at different concentrations. The results of these measurements are discussed in view of both the structures of the materials and the mechanism involved in the association of their molecules. In addition, the experimental results are compared to the theoretical calculations. The loss tangent was shown to increase linearly with molecule length. At 50% concentration, the loss tangent values of n-butyl alcohol, isopropyl alcohol, and benzyl alcohol are approximately 8*10/sup -3/, 6.5*10/sup -3/, and 2.8*10/sup -3/ respectively. The Q-factor values of n-butyl alcohol, isopropyl alcohol, and benzyl alcohol are 200, 228 and 505 respectively.<<ETX>>