Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
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Article Citation - Scopus: 1Sizing of Autonomous Wind/Solar Hybrid Energy Conversion Systems for Urla, Turkey(ACTA Press, 2009) Özerdem, Barış; Ekren, OrhanIn this paper, an optimum sizing procedure of autonomous hybrid (wind + solar) energy system is presented which can be used to satisfy the requirements of given load distribution. The main purpose of this study is to find out an appropriate wind-photovoltaic hybrid energy system to satisfy electricity consumption of GSM (Global System for Mobile communication) base station at Izmir Institute of Technology Campus Area, Urla, Izmir, Turkey. To do this, monthly average daily solar radiation and wind speed data are collected. The monthly average wind speeds are measured at 10 m height during 3 years period on Izmir Institute of Technology Campus Area. The monthly average wind speed values are obtained between 5.7 and 7.7 m/s, on the other hand, the monthly average daily value of solar radiations on horizontal surfaces are ranged from 1.4 to 6.9kWh/m2 at Izmir Institute of Technology Campus Area. The hybrid system considered in the present analysis consists of one 5kW nominal power wind energy conversion systems (WECS), 21.82 m2 of photovoltaic (PV) panels (18 mono crystal PV panels each having 75 W power output) together with a battery storage system.Article Power transmission entropy(Inderscience Enterprises Ltd., 2008) Özdemir, SerhanMechanical transmissions have been characterised traditionally by their transmission efficiencies. This is given by the ratio of the output to the input of the transmitted power. Unfortunately, the power transmission phenomenon is slightly more complex than that. As any designer would agree, each of these transmission localities is a source of uncertainty. Once formulated, this statement of uncertainty would reflect the designer's trust in the transmission. By virtue of the proposed approach, power transmission is no longer a deterministic entity but becomes a probabilistic one. This paper discusses the overlooked uncertainty inherent in every transmission.Article Exergetic Analysis of a Continuous Bi-Axially Oriented Polypropylene (bopp) Film Unit in a Plastic Processing Plant(Inderscience Enterprises Ltd., 2009) Balta, M. Tolga; Hepbaşlı, Arif; Hancıoğlu, Ebru; Özcanlı, Şevket Cihangir; Yılmazer, Ertan; Yurdakul, İbrahim; Dişbudak, ÖzgürThis paper deals with an exergy analysis of the stretching process of bi-axially oriented polypropylene films using a hot oil coiler along with stretching and crystallising unit. Exergy destructions and efficiencies in each of the system components are calculated, while the exergy loss and flow diagram (the so-called Grassmann diagram) is presented for the transverse direction (TD) unit. The so-called functional (on the product or benefit/fuel basis) and universal (on the output/input basis) exergy efficiency values of the TD unit are calculated to be 26.40% and 28.46% at a recommended exhaust air relative humidity of 0.0098 kg water/kg air, respectively.Article Citation - WoS: 12Citation - Scopus: 19Effect of Non-Condensable Gases on Geothermal Power Plant Performance. Case Study: Kızıldere Geothermal Power Plant-Turkey(Inderscience Enterprises Ltd., 2008) Gökçen Akkurt, Gülden; Yıldırım, NurdanNon-Condensable Gases (NCGs) are natural components of geothermal fluids, and they are a source of considerable capital and operating costs for power plants. The NCG content of geothermal steam varies over the world from almost zero to as much as 25% (wt). In this work, the influence of NCGs on the thermodynamic performance of geothermal power plants is analysed for various NCG content and turbine inlet temperatures. The results obtained can be useful on the feasibility study of single flash geothermal power plants. Depending on the NCG content of the field, the performance of the power plant can be determined roughly. © 2008, Inderscience Publishers.Article Local Sparse Coding Control of Cvpsts(Inderscience Enterprises, 2005) Özdemir, SerhanThis paper discusses simulations of a control scheme based on locally sparse coded networks (CMACs) for a novel previously proposed continuously variable transmission (CVT), a hybrid continuously variable power split transmission (CVPST) (Osdemir and Schueller, 2002). Automotive transmissions match the speed and the torque of the power source to the speed and torque requirements of the load. Properly designed CVTs have shown potential to improve efficiency and performance. The main advantage of CMACs is fast computation because of their simple operational principles. Simulation results have shown that memory contents either reach a stable limit cycle or an attractor based on the selection of network parameters and the training method. Both online and offline training are possible.Article Citation - Scopus: 10Exergy Analysis and Performance Evaluation of Kizildere Geothermal Power Plant, Turkey(Inderscience Enterprises Ltd., 2004) Yıldırım, Eda Didem; Gökçen Akkurt, Gülden; Gökçen, GüldenConventional geothermal power plants (GPP) differ from fossil-fuel power plants (FFPP) in many ways. The most specific ones are GPPs, are not cyclic plants and the working fluid is not pure steam. Geothermal steam contains non-condensable gases (NCG) which degrade power plant efficiency. This discrepancy leads to two considerations in energy and exergy analysis of GPPs. One is that the amount of NCGs in the steam cannot be omitted during the calculations; the other is that the dead state composition varies throughout the process. In this work, energy and exergy analysis is conducted to assess the performance of Kizildere GPP under both considerations. The net second law efficiencies of the plant based on reservoir and wellhead exergy are 24.3 and 27.2% respectively. Both indicate that the plant performance is low comparing with the other single-flash GPPs and FFPPs. The losses are mainly associated with high NCG content and low steam fraction of the fluid.Article Citation - WoS: 13Citation - Scopus: 12Mgb2 Superconducting Thin Films Sequentially Fabricated Using Dc Magnetron Sputtering and Thermionic Vacuum Arc Method(Elsevier Ltd., 2007) Okur, Salih; Kalkancı, M.; Pat, Suat; Ekem, Naci; Akan, Tamer; Balbağ, Zafer; Musa, G.; Tanoğlu, MetinIn this work, we discuss fabrication and characterization of MgB2 thin films obtained by sequential deposition and annealing of sandwich like Mg/B/Mg thin films on glass substrates. Mg and B films were prepared using DC magnetron sputtering and thermionic vacuum arc techniques, respectively. The MgB2 thin films showed superconducting critical transition at 33 K after annealing at 650 °C.Article Citation - WoS: 3Citation - Scopus: 5Electrical and Thermal Properties of the Gasb-Fega1.3 Eutectic(MAIK “Nauka/Interperiodica”, 2004) Aliev, M. I.; Khalilova, A. A.; Arsaly, D. G.; Ragimov, R. N.; Tanoğlu, MetinThe electrical conductivity, thermoelectric power, Hall coefficient, and thermal conductivity of the GaSb-FeGa1.3 eutectic were measured in a wide temperature range at different relationships between the directions of the electric current, heat flux, magnetic field, and needlelike metallic inclusions. The results are interpreted in terms of electronic and phonon processes. The metallic inclusions are shown to have a significant effect on the transport properties of the eutectic.Article Citation - WoS: 3Citation - Scopus: 3Tensile Adhesion of Type I Collagen To Titanium Alloy and Calcium Phosphate Coated Surfaces With Different Roughness Values(IOS Press, 2002) Özerdem, BarışThe purpose of total joint arthroplasty is to reduce pain and restore function. Its success depends on the formation of a new bone that stabilizes the prosthesis. The proposed solution for this important problem is to have bio-coated implant surfaces which are more conductive to bone growth. Additionally, collagen has long been used as a matrix for medical applications, because of its biocompatibility and adaptability. In this study, a test method for measuring the tensile adhesion strength of collagen to titanium alloy and calcium phosphate coated surfaces with different roughness values was developed, in order to evaluate how well the collagen adheres to the metallic and bio-coated surfaces. A precision motion system was used to stretch gels that were adherent to the plate surfaces. The tests were done in DMEM solution. The adhesive strength between the collagen gel and plate was significantly higher for calcium phosphate coated surfaces. Adhesive strength was highest in the sample with the highest roughness value.