4 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 4 / 4
Öğe Investigation of low velocity impact behaviors of honeycomb sandwich composites(SpringerLink, 2018-08-09) Topkaya, Tolga; Solmaz, Murat YavuzHoneycomb sandwich composites are used as significant structural members in advanced engineering applications. Thus, it is critical to determine how they behave under impact loading, in addition to other loads. In this study, low velocity impact loading behaviors of honeycomb sandwich composites were experimentally investigated. Almost all of the design parameters of honeycomb sandwich composites were investigated. The results indicated that the core thickness of honeycomb had no effect on the strength of the composite, and the parameter influencing the impact behavior of the specimen the most was the face sheet thickness. When the face sheet thickness of the specimen was increased, the most apparent strength increase was observed in the models using carbon fiber-reinforced composite face sheets. For all face sheet types subject to impact energy of 10 Joules, the upper face sheets of 0.5 mm-thick specimens were perforatedÖğe Electrical properties of safranine T p Si organic inorganic semiconductor devices(Cambridge University, 2010-04-25) Güllü, Ömer; Asubay, Sezai; Biber, Mehmet; Kılıçoğlu, Tahsin; Turut, AbdulmecitWe investigated the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of identically prepared safranine T/p-Si organic/inorganic Schottky devices (total 26 diodes) formed by evaporation of organic compound solution on p-Si semiconductor substrate. It was seen that the safranine T organic thin film on the p-Si substrate showed a good rectifying behavior. The barrier heights and ideality factors of all devices were extracted from the electrical characteristics. The mean barrier height and mean ideality factor from I-V measurements were calculated as 0.59±0.02 eV and 1.80±0.20, respectively. Also, the mean barrier height and mean acceptor doping concentration from C-V measurements were calculated as 0.67±0.10 eV and (6.96±0.37)×1014 cm-3, respectively. The discrepancy in the barrier height values obtained from I-V and C-V characteristics has been attributed to different nature of the measurements. The discrepancy between these values can also be due to the existence of the interfacial native oxide and the organic safranine T thin layer between the semiconductor substrate and top contact metal.Öğe Room temperature I–V and C–V characteristics of Au/mTPP/p-Si organic MIS devices(The European Physical Journal Applied Physics, 2018-05-02) Güllü, Ömer; Pakma, Osman; Özden, ŞadanThe room temperature electrical characteristics of the organic Au/mTPP/p-Si device fabricated by spin coating method were investigated with I–V and C–V measurements. It has been determined that the device has a high rectification coefficient and current transport is dominated by the thermionic emission. The serial resistance value is calculated at 92 ohms with two different approaches. Serial resistance effects were also found to be effective in C–V and G–V measurements. The different barrier heights from the I–V and C–V measurements indicate possible interface and trap states or barrier inhomogeneities.Öğe Experimental investigation of thermal performance in a concentric tube heat exchanger with wavy inner pipe(SpringerLink, 2012-06) Argunhan, Zeki; Çakmak, Gülşah; Yücel, Halit Lutfi; Yıldız, CengizIn this article, the heat transfer, friction factor, and thermal performance factor characteristics of a concentric-tube heat exchanger are examined experimentally. A wavy inner pipe is mounted in the tube with the purpose of generating swirl flow that would help to increase the heat transfer rate of the tube. The examination is performed for a Reynolds number ranging from 2700 to 8800. An empirical correlation is also formulated to match with experimental data of the Nusselt number using the Wilson plot method. In addition, to obtain the real benefits in using the swirl generator at a constant pumping power, the thermal enhancement factor is also determined. Over the range considered, the increases in the Nusselt number, friction factor, and thermal performance factor are found to be, respectively, about 113 %, 81 %, and 196 % higher than those obtained from a smooth-surface inner pipe.
