Can O.,Pamukkale University
Energy Conversion and Management | Year: 2014
In this study, a mixture of biodiesel fuels produced from two different kinds of waste cooking oils was blended in 5% and 10% with No. 2 diesel fuel. The biodiesel/No. 2 diesel fuel blends were tested in a single-cylinder, direct injection, four-stroke, natural aspirated diesel engine under four different engine loads (BMEP 0.48-0.36-0.24-0.12 MPa) and 2200 rpm engine speed. Despite of the earlier start of injection, the detailed combustion and engine performance results showed that the ignition delay with the biodiesel addition was decreased for the all engine loads with the earlier combustion timings due to higher cetane number of biodiesel fuel. Meanwhile the maximum heat release rate and the in-cylinder pressure rise rate were slightly decreased and the combustion duration was generally increased with the biodiesel addition. However, significant changings were not observed on the maximum in-cylinder pressures. In addition, it was observed that the indicated mean effective pressure values were slightly varied depending on the start of combustion timing and the center of heat release location. It was found that 5% and 10% biodiesel fuel addition resulted in slightly increment on break specific fuel consumption (up to 4%) and reduction on break thermal efficiency (up to 2.8%). The biodiesel additions also increased NOx emissions up to 8.7% and decreased smoke and total hydrocarbon emissions for the all engine loads. Although there were no significant changes on CO emissions at the low and medium engine loads, some reductions were observed at the full engine load. Also, CO2 emissions were slightly increased for the all engine loads. © 2014 Elsevier Ltd. All rights reserved.
Selcuk H.,Pamukkale University
Water Research | Year: 2010
In this study, disinfection and formation of disinfection by-products (DBPs) were studied in a photoelectrocatalytic (PEC) treatment system. Disinfection performance of titanium dioxide (TiO2) in the PEC system was determined through Escherichia coli (E. coli) inactivation. Humic acid (HA) was used as a model organic compound and its removal was monitored by total organic carbon (TOC) measurements using 410 nm (color) and 254 nm (UV254) wavelengths. Trihalomethanes (THMs) were measured for the evaluation of DBPs formation during PEC treatment of chloride and HA mixture. It was found that unlike photocatalytic treatment, THMs might form in the PEC system. To investigate the effects of anions on the PEC treatment, chloride (Cl-), sulfate (SO4 2-), phosphoric acid (H2PO4 -)/hydrogen phosphate (HPO4 2-) and bicarbonate (HCO3 -) ions were added separately to the HA and bacterial suspensions. Presence of H2PO4 -/HPO4 2- and HCO3 - ions resulted in inhibitory effects on both HA degradation and E. coli inactivation, which were also examined in the photoanode. It was observed that the presence of HA had a strong inhibitory effect on the disinfection of E. coli. © 2010 Elsevier Ltd.
Kavaklioglu K.,Pamukkale University
Applied Energy | Year: 2011
Support Vector Regression (SVR) methodology is used to model and predict Turkey's electricity consumption. Among various SVR formalisms, ε-SVR method was used since the training pattern set was relatively small. Electricity consumption is modeled as a function of socio-economic indicators such as population, Gross National Product, imports and exports. In order to facilitate future predictions of electricity consumption, a separate SVR model was created for each of the input variables using their current and past values; and these models were combined to yield consumption prediction values. A grid search for the model parameters was performed to find the best ε-SVR model for each variable based on Root Mean Square Error. Electricity consumption of Turkey is predicted until 2026 using data from 1975 to 2006. The results show that electricity consumption can be modeled using Support Vector Regression and the models can be used to predict future electricity consumption. © 2010 Elsevier Ltd.
Alcicek H.,Pamukkale University
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2010
The extensional intramontane grabens that formed in southwestern Anatolia in the Late Cenozoic bear the unique tectono-sedimentary, palaeontological and palynological record of a region that underwent rapid transition from the last compressional pulses of the Alpine orogeny to the tectonic phase of orogen collapse and the onset of neotectonic regime. The change in tectonic regime was accompanied by regional climatic changes, recorded by the sedimentary environments of the basins and evidenced by palaeontological and palynological data. The late Early to mid-Middle Miocene was characterized by a warm and humid subtropical climate with densely forested wetlands. The late Middle to Late Miocene witnessed a change to arid climatic conditions, with grass-dominated steppe ecosystems. The Pliocene climate was warm and humid, with savannah-type open habitats. In terms of their stratigraphic development, the southwestern Anatolian basins form two distinct groups. One group is represented by the Denizli, Söke and Yataǧan basins, which commenced their development in the Early Burdigalian and underwent similar phases of environmental change: (1) the Burdigalian phase of alluvial environment and redbed deposition; (2) the Late Burdigalian-Langhian phase of alluvial sedimentation accompanied by the formation of "terminal" lakes; (3) the Serravallian-Middle Tortonian phase of the formation of shallow perennial lakes; (4) the Middle Tortonian-Messinian phase of lake expansion and deepening, followed by shrinking and shallowing; (5) the Pliocene phase of lake expansion and deepening; and (6) the erosional Quaternary phase of two-stage alluvial sedimentation separated by a high-relief erosional unconformity. The other, younger group of tectonic grabens is represented by the Karacasu, Bozdoǧan, Çameli and Eşen basins, which commenced their development in the earliest Tortonian and underwent common environmental changes: (1) the Tortonian phase of alluvial environment and redbed deposition, coeval with the phase of lake drying in the Denizli, Söke and Yataǧan basins; (2) the Messinian phase of the formation of "terminal" lakes, coeval with the re-establishment of shallow lakes in the three other basins; (3) the Zanclean phase of shallow perennial lakes, coeval with the expansion and deepening of lakes in the other basins; (4) the Piacenzian phase of deep lacustrine environments; (5) the Gelasian phase of shallow lacustrine environments; and (6) the erosional Quaternary phase of two-stage alluvial sedimentation, similar as in the other basins. In spite of the time offset in their development, the two basin groups have been strongly modulated by climate and hence show correlative responses to regional climatic changes. Despite the time offset in their tectonic development, the two basin groups showed correlative environmental changes imposed by regional climatic conditions. The basins were environmentally unified by the Quaternary alluvial phase of their development. In the Late Cenozoic, Anatolia was at the crossroads of fauna migration routes between Africa, Asia and Europe, and the palaeontological data from the southwestern Anatolian basins shed more light on this phenomenon. The study as a whole contributes to a better understanding of the Late Cenozoic environmental, climatical and biogeographical changes in the Eastern Mediterranean. © 2010 Elsevier B.V. All rights reserved.
Nazlioglu S.,Pamukkale University
Energy Policy | Year: 2011
The increasing co-movements between the world oil and agricultural commodity prices have renewed interest in determining price transmission from oil prices to those of agricultural commodities. This study extends the literature on the oil-agricultural commodity prices nexus, which particularly concentrates on nonlinear causal relationships between the world oil and three key agricultural commodity prices (corn, soybeans, and wheat). To this end, the linear causality approach of Toda-Yamamoto and the nonparametric causality method of Diks-Panchenko are applied to the weekly data spanning from 1994 to 2010. The linear causality analysis indicates that the oil prices and the agricultural commodity prices do not influence each other, which supports evidence on the neutrality hypothesis. In contrast, the nonlinear causality analysis shows that: (i) there are nonlinear feedbacks between the oil and the agricultural prices, and (ii) there is a persistent unidirectional nonlinear causality running from the oil prices to the corn and to the soybeans prices. The findings from the nonlinear causality analysis therefore provide clues for better understanding the recent dynamics of the agricultural commodity prices and some policy implications for policy makers, farmers, and global investors. This study also suggests the directions for future studies. © 2011 Elsevier Ltd.