Gumuhane University


Gumuhane University

Time filter
Source Type

Damla N.,Batman University | Cevik U.,Karadeniz Technical University | Kobya A.I.,Karadeniz Technical University | Celik A.,Giresun University | And 2 more authors.
Radiation Measurements | Year: 2011

In this study the distribution of natural radionuclides (226Ra, 232Th, 40K) in brick and roofing tile samples commonly used as building materials in Turkey was measured by using gamma spectrometry. The activity concentrations, radium equivalent activities (Raeq), representative level index, indoor absorbed dose rate in air values and annual effective dose due to the intake of the above-mentioned radionuclides in the brick and roofing tile samples were estimated to assess the radiation hazard for people living in dwellings made of the materials studied. The measured average activity concentrations of 226Ra, 232Th and 40K were 34 ± 14, 34 ± 13 and 462 ± 175, respectively, for brick samples. For roofing tile, the average activity concentrations of 226Ra, 232Th and 40K were measured to be 34 ± 14, 33 ± 12 and 429 ± 161 -1, respectively. The concentrations for these natural radionuclides were compared with the reported data of other countries. The Raeq values of all samples were lower than the limit of 370, equivalent to a gamma dose of 1.5 mSv.a-1 recommended by OECD. This study shows that the measured brick and roofing tile samples do not pose any significant source of radiation hazard and are safe to be used as building materials. Moreover, the experimental mass attenuation coefficients (μ/ρ) of brick and roofing tile samples were determined in the energy range 80-1332 keV using the gamma ray transmission method. The experimental mass attenuation coefficients were compared with theoretical values obtained using XCOM. It was found that the computed values and the experimental results of this work are in good agreement with those reported in the literature. The chemical compositions and structural analysis (XRD) of the brick and roofing tile samples are also presented. © 2011 Elsevier Ltd. All rights reserved.

Livaoglu R.,Uluda University | Cakir T.,Gumuhane University | Dogangun A.,Uluda University | Aytekin M.,University of Bahrain
Ocean Engineering | Year: 2011

The reliability and/or stability of the lifeline structures against failure under seismic loads are of critical concern, and must be studied carefully. Therefore, the main objective of this paper is to demonstrate the commonly encountered backfill effects on the dynamic response of rectangular tanks. However, only the exterior wall of the tank which interacts with both the backfill and fluid is tackled, as each part of the structure shows considerable differences in terms of both the load bearing mechanisms and the geometrical and positional differences. Finite element analyses are employed, taking into consideration the fluidwallbackfill interaction. The analyses are conducted to observe whether or not both backfill and wall behavior can be affected by variation of the internal friction angle. For that purpose, some comparisons are made on vertical displacements of the backfill, roof displacements, stress responses, etc., by means of internal friction angle variations of the backfill from 25° to 40°. Consequently, it is observed that the variations on maximum vertical displacements are affected considerably. In contrast, the maximum stress responses are affected partially. However, the inertial effects of the backfill show that pseudo-static approximations may be insufficient to understand the dynamic behavior of the backfillwallfluid system. © 2011 Elsevier Ltd. All rights reserved.

Karabdak S.M.,Karadeniz Technical University | Karabdak S.M.,Gumuhane University | Kaya S.,Gumuhane University | Evik U.,Karadeniz Technical University | Elik A.,Giresun University
Radiation Measurements | Year: 2011

Reducing count losses and pile-up pulse effects in quantitative and qualitative analysis is necessary for accuracy of analysis. Therefore, the proper peaking time for particular detector systems is important. The characteristic X-rays emitted from pure some elements were detected by using an Ultra-LEGe detector connecting a Tennelec TC 244 spectroscopy amplifier at different peaking time modes. Overall pulse widths were determined by an HM 203-7 oscilloscope connecting amplifier. The proper peaking time for Ultra-LEGe is determined as 3.84 μs. © 2011 Elsevier Ltd. All rights reserved.

Akpinar A.,Gumuhane University | Akpinar A.,Karadeniz Technical University | Kaygusuz K.,Karadeniz Technical University
Renewable and Sustainable Energy Reviews | Year: 2012

Southeastern Anatolia Project (GAP) region in Turkey is rich in water for irrigation and hydroelectric power. The Euphrates and Tigris Rivers represent over 28% of the nation's water supply by rivers, and the economically irrigable areas in the region make up 20% of those for the entry country. Turkey has a total gross hydropower potential of 433 GWh/yr, but only 125 GWh/yr of the total hydroelectric potential of Turkey can be economically used. By the construction of new hydropower plants, 36% of the economically usable potential of the country would be tapped. The GAP region has a 22% share of the country's total hydroelectric potential, with plans for 22 dams and 19 hydroelectric power plants. Once completed, 27 billion kWh of electricity will be generated annually. © 2011 Elsevier Ltd. All rights reserved.

Akpinar A.,Gumuhane University | Komurcu M.H.,Karadeniz Technical University | Kankal M.,Karadeniz Technical University
Renewable and Sustainable Energy Reviews | Year: 2011

The main objective in doing the present study is to investigate the sustainable development of hydropower plants in the oruh river basin of Turkey, which is least problem river of Turkey in respect to international cooperation as compared with Turkey's other trans-boundary waters. Initial studies concerning the hydropower production potential in oruh basin had been carried out by Turkish authorities in the late 1960s. Total installed power capacity and annual average energy generation of 37 dams and run of river (without storage) hydropower plants developed at various project stages by The Electrical Power Resources Survey and Development Administration (EE) in oruh basin are 3132.70 MW and 10.55 TWh/yr, respectively. Today, this generation value corresponds 6.45% of Turkey's energy consumption in 2006 while it meets 6.3% of total electricity energy production of Turkey which is equal to 167.9 TWh/yr in 2006. Besides, this potential developed at various project stages in oruh basin will provide 24.1% of Turkey's hydroelectric energy generation being equal to 43.8 TWh/yr in 2006. © 2010 Elsevier Ltd. All rights reserved.

Bayraktar A.,Karadeniz Technical University | Sevim B.,Karadeniz Technical University | Sevim B.,Gumuhane University | Can Altunisik A.,Karadeniz Technical University
Finite Elements in Analysis and Design | Year: 2011

This paper investigates the effects of finite element model updating on nonlinear seismic response of arch damreservoirfoundation systems. The highest arch dam in Turkey named Berke is selected for the numerical and experimental applications. Firstly, 3D finite element model of Berke Dam was constituted using an ANSYS software. In the analytical modeling, arch damreservoirfoundation interaction is represented by Lagrangian approach. Then ambient vibration tests were conducted to dam for four days, and experimental dynamic characteristics were estimated using an Enhanced Frequency Domain Decomposition technique. Experimental characteristics are compared with those of analytical obtained by the linear finite element analysis of the coupled system. Good agreement between mode shapes is observed during this comparison, though natural frequencies disagree by 1520%. The linear finite element model of Berke Dam was updated by adjusting the material properties of the dam and foundation. By introducing the DruckerPrager damage criterion, the updated linear finite element model was extended into a nonlinear model. Nonlinear seismic behavior of Berke Dam was determined considering the acceleration record of Adana-Ceyhan, Turkey, earthquake in 1998 that occurred near the arch dam region. It is highlighted that the finite element model updating provides a significant influence on the nonlinear seismic response of arch dams. © 2010 Elsevier B.V. All rights reserved.

Nas A.,Karadeniz Technical University | Kaya E.C.,Gumuhane University | Kantekin H.,Karadeniz Technical University | Sokmen A.,Karadeniz Technical University | Cakr V.,Karadeniz Technical University
Journal of Organometallic Chemistry | Year: 2011

This work reports on a new symmetrically substituted metal-free phthalocyanine and its transition metal complexes which were prepared by a condensation of N,N′-[propan-1,3-diilbis(tiyoetan-2,1-diil)]bis(4- methylbenzenesulfonamid) (1) and 1,2-bis (2-iodomercaptoethyl)-4,5- dicyanobenzene (2) with NiCl2, ZnCl2, CoCl2, CuCl2,and PbO salts in 2-(dimethylamino)ethanol, respectively. The phthalocyanines bearing thia and aza donor atoms at the peripheral position were characterized by IR, UV-Vis, 1H NMR, 13C NMR, Mass spectra, and elemental analysis data. The thermal behaviors of 4-9 were investigated by TG/DTA. Novel phthalocyanines were also investigated for enlightening their possible biological activities by employing antimicrobial (antibacterial and antifungal), antineoplastic and antioxidative assays. Of all tested, four samples exhibited antimicrobial activity against test microorganisms, among which, Branhamella catarrhalis was the most sensitive one with a MIC value around 0.312 mg/mL followed by a yeast, Candida albicans (MIC. 0.625 mg/mL). Due to their colored nature, the samples were found not to be applicable for antioxidative and antineoplastic assays. © 2010 Elsevier B.V. All rights reserved.

Sevim B.,Gumuhane University | Sevim B.,Karadeniz Technical University | Bayraktar A.,Karadeniz Technical University | Altuniik A.C.,Karadeniz Technical University | And 2 more authors.
Finite Elements in Analysis and Design | Year: 2011

The focus of this paper is to illustrate the importance of model calibration and in situ vibration testing by comparing the finite element model predictions of the earthquake response of the two historical arch bridges, Osmanl and enyuva, before and after model calibration. The three-dimensional finite element models of these two arch bridges, built in the ANSYS finite element program, are used to predict bridge dynamic characteristics, such as natural frequencies and mode shapes. Following the analytical study, ambient vibration tests were conducted to experimentally obtain dynamic characteristics of these two bridges. During ambient vibration tests, accelerometers were placed at several points on the bridge to collect the vibration response due to natural and operational excitation sources. Enhanced frequency domain decomposition and stochastic subspace identification techniques were used to extract the experimental natural frequencies, mode shapes and damping ratios. Finite element models of the two arch bridges were adjusted such that the model predictions reproduce the ambient vibration test results with increased fidelity. The behavior of the masonry arch bridges under earthquake excitation recorded during the Erzincan Earthquake in 1992 is simulated by both the initial and adjusted finite element models. The findings of this study emphasize the importance of model calibration and ambient vibration testing. © 2010 Elsevier B.V.

Dede T.,Karadeniz Technical University | Bekirolu S.,Gumuhane University | Ayvaz Y.,Yildiz Technical University
Applied Soft Computing Journal | Year: 2011

This study is concerned with encoding types such as value encoding and binary encoding for continuous and discrete optimization with a GA, which is coded in FORTRAN and considers stress and displacement constraints, in view of weight minimization of truss structures. Moreover, when continuous optimization is performed, the challenge of huge search space due to the effort of considering continuous set of design variables is overcame by a mechanism introduced as restricted range approach (RRA) in this study. In comparison with the literature, it is concluded that the program developed in this study can be effectively used in the weight minimization of truss structures. It is also came to the conclusion that value encoding overcomes the adverse effects of Hamming-cliff, and that value encoding requires less computer memory and time, never destroys the fit chromosome. © 2010 Elsevier B.V. All rights reserved.

Sezer I.,Gumuhane University
International Journal of Thermal Sciences | Year: 2011

This study investigates the use of dimethyl ether and diethyl ether in diesel engines as alternative fuels. A direct injection diesel engine was simulated via a thermodynamic cycle model for investigation. Thermodynamic and performance parameters besides emissions determined and compared for diesel, dimethyl ether and diethyl ether fuels at two different states. The results showed that dimethyl ether and diethyl ether presented a lower cylinder temperature and pressure, and thus a lower engine performance than diesel fuel for the equal injection conditions. The brake power declines about 32.1% and 19.4% at 4200 rpm while brake specific fuel consumption increases about 47.1% and 24.7% at 2200 rpm for dimethyl ether and diethyl ether, respectively. Engine performance for dimethyl ether and diethyl ether extensively improves for the same equivalence ratio condition, but a more amount of fuel is needed about 64% for dimethyl ether and 32% for diethyl ether. The gains in the brake power by dimethyl ether and diethyl are about 13.6% and 6% at 4200 rpm compared to diesel fuel. The brake specific fuel consumption is also higher about 43.5% for dimethyl ether and 23.6% for diethyl ether than diesel fuel. The brake thermal efficiency for dimethyl ether and diethyl is generally better than diesel fuel. The lower carbon dioxides are obtained by dimethyl and diethyl ethers at all conditions, while carbon monoxide and nitrogen oxide are slightly higher for dimethyl and diethyl ethers at equal equivalence ratio condition. © 2011 Elsevier Masson SAS. All rights reserved.

Loading Gumuhane University collaborators
Loading Gumuhane University collaborators