Bicen Y.,Duzce University
Electric Power Systems Research | Year: 2017
Insulated power cables are the most critical devices used in electrical network for urban areas. Also, lifespan knowledge of these devices is the important information for decision-makers to make their investment planning. This study has presented a practical method for estimating the remaining lifetime of a power cable. The validation of the method has been tested under two different cases for 154 kV XLPE insulated underground power cable system. Power cable thermal network has been modeled for a short-duration transient according to electrical analogy. Lifetime monitoring has been carried out by considering loss of life trend depending on the load raising an annual basis. The results show that the accuracy of the remaining service life estimation is related to receiving data with high sample-rate and determining loss of life trend curve belonging to the power cable. The realistic estimations are carried out using trend-adjusted exponential smoothing. © 2016 Elsevier B.V.
Toklu E.,Duzce University
Renewable Energy | Year: 2017
Biomass is the most widely used renewable energy source in the world today. It is used mostly in solid form and, to a lesser extent, in the form of liquid fuels and gas. The utilization of biomass for energy production has increased at only a modest rate in modern times. Biomass is the major source of energy in rural Turkey. Biomass is used to meet a variety of energy needs, including generating electricity, heating homes, fueling vehicles and providing process heat for industrial facilities. Biomass potential includes wood, animal and plant wastes. Among the biomass energy sources, fuel wood seems to be the most interesting because its share of the total energy production of Turkey is high at 14%. The total biomass energy potential of Turkey is about 33 million tons of oil equivalents (Mtoe). The amount of usable biomass potential of Turkey is approximately 17 Mtoe. The electrical production potential from usable bioenergy sources are 73 MW in 2010 and corporate income and represent more than 280,000 jobs. This study shows that there is important biomass energy potential for climate change mitigation and energy sustainability in Turkey. © 2017 Elsevier Ltd
Gerengi H.,Duzce University
Industrial and Engineering Chemistry Research | Year: 2012
The influence of date palm (Phoenix dactylifera L.) (PDL) fruit juice on 7075 type aluminum (AA7075) alloy in 3.5% NaCl solution was investigated by Tafel extrapolarization and electrochemical impedance spectroscopy. It was found that PDL fruit juice acted as a slightly cathodic inhibitor, and inhibition efficiencies increased with the increase of PDL fruit juice concentration. The adsorption of the inhibitor on the metal surface was found to obey the Temkin adsorption isotherm and has a physisorption mechanism. © 2012 American Chemical Society.
Akgul M.,Duzce University
Composites Part B: Engineering | Year: 2013
The main objective of this study was to investigate the possibilities of utilizing stinging nettle (Urtica dioica L.) stalks as a fiber-nettle mixture at various percentages to produce fiberboards for general purposes. Also, we aimed to investigate the possibility of utilizing stinging nettle in panel production, thus helping overcome the raw material shortage that the industry is facing. As wood fiber, pine (Pinus nigra V.), beech (Fagus orientalis L.) and oak (Ouercus robur L.) fiber mixtures (30%, 35% and 35%, respectively) were utilized. In panel production the only variable tested was the addition of nettle stalks at various percentages to the wood fibers. The resultant panels were compared with the panels produced using 100% wood fiber. The results indicated that panels could be produced utilizing nettle stalks up to 40% addition without falling below the properties required in the standards. Higher addition levels diminished the elastic modulus and bending strength below the acceptable level. The observed results indicated that adding nettle stalks to the wood fibers to produce fiberboards at certain percentages would result in panels acceptable to the standards and would be of assistance to the raw material shortage in the Turkish panel industry. © 2012 Elsevier Ltd. All rights reserved.
Set E.,Duzce University
Computers and Mathematics with Applications | Year: 2012
A new identity similar to an identity proved in Alomari et al. (2010)  for fractional integrals is established. Then by making use of the established identity, some new Ostrowski type inequalities for RiemannLiouville fractional integral are established. Our results have some relationships with the results of Alomari et al. (2010), proved in  and the analysis used in the proofs is simple. © 2011 Elsevier Ltd. All rights reserved.
Tutkun N.,Duzce University
Energy and Buildings | Year: 2014
Recently Turkey's electricity demand has shown a considerable increase due to its population and economic growths. It is understandable that this may be very influential on electricity price on market as well as other factors such as an increase in natural gas price, etc. It should be noted that the half of Turkey's electricity generation is supplied from natural gas and 95% of this source is imported from other countries. However, Turkey is rich in wind and solar energy potentials to generate electricity and it is believed that this makes a considerable impact on reducing high electricity unit cost to competitive one. In this regard, these potentials can be utilized for electricity generation in order to meet a significant portion of the power demanded by residential houses through a PV/wind system. The electricity cost of the renewable system can be minimized by optimally scheduling generated and consumed powers. In this paper, optimal power scheduling in such systems is carried out by using the BCGA and the SVM methods. The results indicated that the proposed approach was able to minimize the operation cost in the hybrid system through the optimal power scheduling. © 2014 Elsevier B.V.
Toklu E.,Duzce University
Renewable Energy | Year: 2013
The necessity of minimizing environmental impacts of energy use, particularly those with potentially worrisome global effects, is perhaps the greatest challenge resulting from the twentieth century's energy advances. The renewable energy technologies of wind, biofuels, solar thermal and photovoltaics are finally showing maturity and the ultimate promise of cost competitiveness. Turkey's demand for energy and electricity is increasing rapidly and heavily dependent on expensive imported fossil energy resources that place a big burden on the economy and environmental pollution is becoming an important concern in the country. With respect to global environmental issues, Turkey's carbon dioxide emissions have grown along with its energy consumption. States have played a leading role in protecting the environment by reducing emissions of greenhouse gases. In this regard, renewable energy resources appear to be the one of the most efficient and effective solutions for clean and sustainable energy development in Turkey. This study shows that there is huge potential for renewable energy in Turkey, especially hydropower, biomass, geothermal, solar and wind. © 2012 Elsevier Ltd.
Korkut S.,Duzce University
Industrial Crops and Products | Year: 2012
Thermally modified wood is being increasingly offered in Europe as an alternative to preservative-treated timber. The aim of this study is to determine the change of various physical properties (oven-dry density, air-dry density, weight loss, swelling and anti-swelling efficiency (ASE)), compression strength parallel to grain, colour difference (Δ E), glossiness and surface roughness of sapele (Entandrophragma cylindricum), limba (Terminalia superba) and iroko (Chlorophora excelsa) woods after heat treatment under different temperatures and durations. For this study wood specimens were subjected to heat treatment under atmospheric pressure and air at two different temperatures (160 °C and 180 °C) and two different times (2. h and 4 h). Multiple physical properties (oven-dry density, air-dry density, and swelling), compression strength parallel to the grain and surface roughness of the heat-treated wood and control samples were tested. A stylus method was employed to evaluate the surface characteristics of the samples. Roughness measurements using the stylus method were made in the direction perpendicular to the fiber. Four main roughness parameters which are mean arithmetic deviation of profile (Ra), mean peak-tovalley height (Rz), root mean square roughness (Rq), and maximum roughness (Ry) obtained from the surface of wood were used to evaluate the effect of heat treatment on the surface characteristics of the specimens. Significant difference was found (P= 0.05) between physical and technological properties, and surface roughness parameters (Ra, Rz, Ry, Rq) at two temperatures and two durations of heat treatment. Based on the findings of this study, the results showed that oven-dry density, air-dry density, swelling, compression strength parallel to grain and surface roughness values decreased with increasing treatment temperature and treatment time. Thus, sapele, iroko, and limba wood can be utilized with proper heat treatment techniques for outdoor and indoor applications. © 2011 Elsevier B.V.
Kivak T.,Duzce University
Measurement: Journal of the International Measurement Confederation | Year: 2014
In this paper, the Taguchi method and regression analysis have been applied to evaluate the machinability of Hadfield steel with PVD TiAlN- and CVD TiCN/Al2O3-coated carbide inserts under dry milling conditions. Several experiments were conducted using the L18 (2 × 3 × 3) full-factorial design with a mixed orthogonal array on a CNC vertical machining center. Analysis of variance (ANOVA) was used to determine the effects of the machining parameters on surface roughness and flank wear. The cutting tool, cutting speed and feed rate were selected as machining parameters. The analysis results revealed that the feed rate was the dominant factor affecting surface roughness and cutting speed was the dominant factor affecting flank wear. Linear and quadratic regression analyses were applied to predict the outcomes of the experiment. The predicted values and measured values were very close to each other. Confirmation test results showed that the Taguchi method was very successful in the optimization of machining parameters for minimum surface roughness and flank wear in the milling the Hadfield steel. © 2013 Elsevier Ltd. All rights reserved.
Ozgan E.,Duzce University
Expert Systems with Applications | Year: 2011
In this study, the Marshall Stability (MS) of asphalt concrete under varying temperature and exposure times was modeled by using artificial neural network. In order to investigate the MS based on physical properties, exposure time and environment temperature, exposure times of 1.5, 3, 4.5 and 6 h and temperatures of 30 °C, 40 °C and 50 °C were selected. The results showed that at the environment temperature of 17 °C the stability of the asphalt core samples decreased by 40.16% at 30 °C after 1.5 h and 62.39% after 6 h. At 40 °C, the decrease was 74.31% after 1.5 and 78.10% after 6 h. At 50 °C the stability of the asphalt decreased by 83.22% after 1.5 h, and 88.66% after 6 h. Experiment results and ANN model exhibited good correlation for this reason the ANN method could be used to model the MS. © 2010 Elsevier Ltd. All rights reserved.