Time filter

Source Type

Primer D.N.,University of Pennsylvania | Karakaya I.,University of Pennsylvania | Karakaya I.,Osmaniye Korkut Ata University | Tellis J.C.,University of Pennsylvania | Molander G.A.,University of Pennsylvania
Journal of the American Chemical Society | Year: 2015

Single-electron-mediated alkyl transfer affords a novel mechanism for transmetalation, enabling cross-coupling under mild conditions. Here, general conditions are reported for cross-coupling of secondary alkyltrifluoroborates with an array of aryl bromides mediated by an Ir photoredox catalyst and a Ni cross-coupling catalyst. © 2015 American Chemical Society.


Demir A.,Osmaniye Korkut Ata University | Laman M.,Cukurova University | Yildiz A.,Cukurova University | Ornek M.,Mustafa Kemal University
Geotextiles and Geomembranes | Year: 2013

This study aims at experimentally explaining the potential benefits of geogrid reinforced soil footings using large scale field tests. A total of 16 field tests were carried out to evaluate the effects of replacing natural clay soil with stiffer granular fill layer and single-multiple layers of geogrid reinforcement placed into granular fill below circular footings. The large scale field tests were performed using different size of the circular footing diameters which have 0.30, 0.45, 0.60 and 0.90. m. The results of testing program are presented in terms of subgrade modulus and bearing capacity. These values were calculated for each test at settlements of 10, 20 and 30. mm. Based on the test results, it is shown that the use of granular fill and geogrid for reinforced soil footings (RSF) have considerable effects on the subgrade modulus and bearing capacity. Finally, the field test results are compared to the analytical methods proposed by different researchers including the statistical correlations. © 2012.


Ugur F.A.,Osmaniye Korkut Ata University
Radiation protection dosimetry | Year: 2013

The activity level and possible radiological impacts of naturally occurring radionuclides on the health of workers and members of the public, as a result of utilisation of blast furnace slag (BFS) samples as a substitute for aggregate in road construction were investigated by using a gamma-ray spectrometer and potential exposure scenarios given in Radiation Protection 122. The mean activity concentrations of the (226)Ra, (232)Th and (40)K in BFS samples were found to be 152.4, 54.9 and 183.1 Bq kg(-1), respectively. These values are compared with typical values measured in BFS samples from the European Union countries, which are 270, 70 and 240 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The values of radium equivalent activity index calculated for BFS samples were within the recommended safety limits. The highest total annual effective doses evaluated as 0.9 and 0.4 mSv y(-1) for members of the public and workers, respectively, were lower than the annual limit of 1 mSv y(-1).


Inhibition of the corrosion of mild steel in 1.0 M HCl solution by a Schiff base compound named 2-[(4-phenoxy-phenylimino)methyl]-phenol (APS) was investigated at different temperatures (25-55 °C) using electrochemical measurements. The inhibition efficiency increased as APS concentration and temperature increased. It was found that adsorption for APS on mild steel complies with the Langmuir adsorption isotherm in all studied temperature. Thermodynamic parameters (ΔGads, ΔHads and ΔSads) for APS adsorption on mild steel were found out and discussed at each temperature. Time dependency of mild steel in 1.0 M HCl solution in the absence and presence of APS was also studied. The surface morphology of mild steel was examined via SEM analysis. © 2011 Elsevier B.V. All rights reserved.


Demir H.,Osmaniye Korkut Ata University
International Journal of Refrigeration | Year: 2013

A microwave assisted zeolite-water adsorption heat pump system was designed, manufactured and investigated experimentally. The influence of operation time of microwave oven on performance of the adsorption heat pump was studied. The performance criteria: coefficient of performance, specific cooling power and volumetric cooing power, were calculated for the designed and tested adsorption heat pump system. The regeneration of adsorbent bed was achieved very rapidly (35 min) by using microwave heating system. The poor thermal conductivity of adsorbent did not affect the periods of isosteric heating and isobaric desorption processes. © 2013 Elsevier Ltd and IIR. All rights reserved.


Demir H.,Osmaniye Korkut Ata University
Applied Thermal Engineering | Year: 2013

The heat transfer problem of an adsorption heat pump during the regeneration of adsorbent bed was investigated numerically. A numerical analysis of the heat and mass transfer in an adsorbent bed during an adsorption heat pump cycle, achieved with both conventional and microwave heating, was successfully simulated. The influence of the microwave heating on the performance criteria of an adsorption heat pump was investigated. The distributions of temperature, pressure and adsorbate concentration of adsorbent bed through the radius of the bed were analyzed. The Clausius-Clapeyron diagram was constructed for both cases. The period of the cycle was improved by about 20% with the microwave regeneration, since the period of the isobaric desorption process for a microwave heated cycle was enhanced by 51% relative to the period of the isobaric desorption process for a conventional heated cycle. The COP for the microwave heated cycle was improved by 61% according to the conventional heated cycle. © 2012 Elsevier Ltd. All rights reserved.


Unal S.,Osmaniye Korkut Ata University | Yilmaz T.,Osmaniye Korkut Ata University
Applied Thermal Engineering | Year: 2015

Air-conditioning compressors of the buses are usually operated with the power taken from the engine of the buses. Therefore, an improvement in the air-conditioning system will reduce the fuel consumption of the buses. The improvement in the coefficient of performance (COP) of the air-conditioning system can be provided by using the two-phase ejector as an expansion valve in the air-conditioning system. In this study, the thermodynamic analysis of bus air-conditioning system enhanced with a two-phase ejector and two evaporators is performed. Thermodynamic analysis is made assuming that the mixing process in ejector occurs at constant cross-sectional area and constant pressure. The increase rate in the COP with respect to conventional system is analyzed in terms of the subcooling, condenser and evaporator temperatures. The analysis shows that COP improvement of the system by using the two phase ejector as an expansion device is 15% depending on design parameters of the existing bus air-conditioning system. © 2015 Elsevier Ltd. All rights reserved.


Yaniktepe B.,Osmaniye Korkut Ata University | Koroglu T.,Osmaniye Korkut Ata University | Savrun M.M.,Osmaniye Korkut Ata University
Renewable and Sustainable Energy Reviews | Year: 2013

Turkey is a country that is dependent on foreign energy; the majority of Turkey's energy needs are supplied through imports. Renewable energy sources are becoming important in Turkey due to both the country's energy dependency and the disadvantages of using fossil fuels. Turkey has begun to use renewable energy sources, especially wind energy, which has a high potential in the country. Moreover, investigations of and investments in wind power have increased recently. This study investigates the wind energy potential that is a result of the distribution of wind speeds in Osmaniye,which is located east of the Mediterranean Sea in Turkey. The Weibull and Rayleigh distribution methods, which are generally used for this type of wind energy study, are employed. The approximate wind energy potential was obtained and indicates whether the region is suitable for related investments. Wind data, consisting of wind speed, direction and flow time at a height of 10 m, were collected by the Turkish State Meteorological Service for a period of 44 months, from January 2008 to August 2011. To determine the Weibull parameters, a graphical method is used; hence, the mean annual value of the shape parameter (k) is between 1.00 and 1.04, while the annual value of the scale parameter (c) is between 1.59 and 1.66 m/s. The average wind speed and wind potential energy are 2.23 m/s and 24.587 W/m 2, respectively. © 2013 Elsevier Ltd.


Kaska O.,Osmaniye Korkut Ata University
Energy Conversion and Management | Year: 2014

Energy, in conjunction with exergy, analysis of a waste heat driven Organic Rankine Cycle (ORC) is performed. Using actual plant data, performance of the cycle and pinpoint sites of primary exergy destruction are assessed. Furthermore, variations of energy and exergy efficiencies of the system with evaporator/condenser pressures, superheating and subcooling are illustrated. It is observed from the analysis that, the energy and exergy efficiencies of the system are 10.2%; 48.5% and 8.8%; 42.2%, respectively, for two different actual cases. Exergy destruction of subcomponents is also quantified. The components with greater exergy destructions to lower one can be listed as evaporator, turbine, condenser and pump. Evaporation pressure has significant effect on both energy and exergy efficiencies. Pinch-point analysis is, also performed to determine effects of heat exchange process, in the evaporator, on the net power production. © 2013 Elsevier Ltd. All rights reserved.


The criticality problem for one-speed neutrons in a uniform finite slab is studied in the case of a combination of forward and backward scattering with linearly anisotropic scattering using UN method based on the Chebyshev polynomials of second kind. The effect of the linear anisotropy on the critical thickness of the slab is investigated. The critical slab thicknesses are calculated by using Marshak boundary condition for various values of the anisotropy parameters and they are presented in the tables. In comparison to the results obtained by other methods, the results of this study are in compatible with the former ones. © 2013 Elsevier Ltd. All rights reserved.

Loading Osmaniye Korkut Ata University collaborators
Loading Osmaniye Korkut Ata University collaborators