Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Araz, Onur(15)
- Ozturk, Samet(14)
- Ozyurt, E.(9)
- Turk, Veysel(9)
- Reis, Hatice Catal(7)
- Beder, Murat(6)
- Erdogdu, Ferruh(6)
- Peker, Iskender(6)
- Erol, Ismail(5)
- Kaygusuz, Abdullah(5)
- Ozturk, Kasif Furkan(5)
- Wang, Y.C.(5)
- Akpinar, Adem(4)
- Akçay, Serhatcan Berk(4)
- Coskun, Eda(4)
- Kankal, Murat(4)
- Kaya, Selim(4)
- Liu, Shuxiang(4)
- Ozden, Talat(4)
- Seferoğlu, Mehmet Tevfik(4)
- Varol, Temel(4)
- Öztürk, Serkan(4)
- Akinoglu, Bulent G.(3)
- Alemdag, Selcuk(3)
- Arslan, Mehmet(3)
- Cakir, Tufan(3)
- Gurocak, Zulfu(3)
- Gücer, Mehmet Ali(3)
- Günen, Mehmet Akif(3)
- Kaya, Ali(3)
- Mert, Behic(3)
- Mızrak, Sefa(3)
- Saydam Eker, Çiğdem(3)
- Tasci, Caner(3)
- Çelik, Necati(3)
- Ünlü, Ramazan(3)
- Şan, Murat(3)
- Akpinar, A.(2)
- Akpinar, Merve(2)
- Aksa, Hüseyin Can(2)
Yayınlar
- MakaleAçık Erişim2015A simple regression based approach to estimate deformation modulus of rock masses
Alemdag, Selcuk; Gurocak, Zulfu; Gokceoglu, Candan
Rock mass characterization has a crucial importance in rock engineering applications including foundation design, slope design, support design and others. For these purposes, it is necessary to determine some input parameters for design, such as deformation modulus (Em), uniaxial compressive strength (σci) and Poisson ratio (υ). The Em is an important input parameter and the practical and economical way to determine this parameter is to apply a rock mass classification system and estimate using the rock mass properties. Data from four different sites were used in the study. The values of Em were calculated using the existing empirical equations based on the Rock Mass Rating (RMR89) system. Furthermore, pressuremeter tests were carried out to determine the Em in one of the sites. The relationship between the RMR89 and the Em was obtained via simple regression analysis using the Em calculated from empirical equations based on RMR89 system. Afterwards, performance of the equation obtained from regression analyses was examined and compared the predicted Em values with experimental values with respect to the R2 values using the data of fourth site. Overall R2 value was found to be as 0.75.
- MakaleYalnız künye2015Geochronology, geochemistry, and petrogenesis of the Eocene Bayburt intrusions, Eastern Pontides, NE Turkey: Evidence for lithospheric mantle and lower crustal sources in the high-K calc-alkaline magmatism
Kaygusuz, Abdullah; Öztürk, Mürşit
Eocene I-type plutons are widespread in the Eastern Pontides, Northeastern Turkey. Geochemical and isotopic results on two Eocene intrusive bodies located in the southern zone of the Eastern Pontides were utilized to achieve a proper reconstruction of their origin. Based on laser ablation ICP-MS U-Pb zircon dating, Kiliçkaya and Kozluk intrusions present similar 206Pb/238U versus 207Pb/235U concordia ages of 46.75±0.79 and 46.9±0.68 Ma, respectively. Both intrusions exhibit similar petrographical, geochemical, and isotopical features, and contain abundant mafic microgranular enclaves (MMEs). The intrusive rocks are composed of diorite, tonalite, and granodiorite, whereas MMEs are composed of diorite. Both the intrusive rocks and the MMEs are I-type, high-K calc-alkaline in composition and display a metaluminous character. They are enriched in large-ion lithophile and light rare-earth elements and are depleted in high-field strength elements. The intrusive rocks show moderate variation in 87Sr/86Sr(i) (0.70531-0.70576), εNd(i) (+0.3 to -0.5), and δ18O values (+6.6 to +6.9), as well as Nd model ages (0.73-0.82Ga). Their Pb isotopic ratios are 206Pb/204Pb=18.67-18.86, 207Pb/204Pb=15.61-15.62, and 208Pb/204Pb=38.62-39.03. Although the isotope signatures of MMEs (87Sr/86Sr(i)=0.70528-0.70561; εNd(i)=+0.7 to -0.3; δ18O=+6.7 to +6.8) are significantly similar to those of the host rocks, the MMEs are characterized by relatively low contents of SiO2 (57-59wt.%), low aluminum saturation index (0.8-0.9), and high Mg numbers (31-36). All of these data suggest magma generation by mixing of enriched lithospheric mantle- and lower crustal-derived melts. Moreover, Sr-Nd isotopic modeling reveals ~17% to 23% lower crustal magma contribution to the mantle component.
- MakaleYalnız künye2014Microstructural, mechanical and tribological properties of Al-7Si-(0-5)Zn alloys
Alemdaǧ, Yasin; Beder, Murat
A series of Al-7Si-(0-5)Zn alloys were produced by permanent mould casting and their microstructure, mechanical and tribological properties were investigated in as-cast state. The microstructure of Al-7Si alloy consisted of α-Al dendrites surrounded by eutectic Al-Si mixture and a small amount of primary silicon particles. Addition of zinc into Al-7Si alloy resulted in the formation of α-solid solution and an increase in size and volume fraction of primary silicon particles. Moreover, these particles gathered inside interdendritic regions of the ternary Al-7Si-Zn alloys. The density, strength and hardness of Al-7Si-Zn alloys increased continuously with increasing zinc content, but their elongation to fracture and impact energy showed a reverse trend. It was also observed that zinc had no significant effect on the friction coefficient of the alloys, but their wear volume decreased with increasing zinc content up to 4%, above which the trend reversed. The wear surfaces of the alloys were characterized mainly by smearing layer with some degree of oxidation. In addition, delamination and fine scratches were observed on the worn surface. It was concluded that the addition of zinc up to 4% improves both mechanical and wear behaviour of Al-7Si alloy.
- MakaleYalnız künye2013Effects of laminate carbon/epoxy composite patches on the strength of double-strap adhesive joints: Experimental and numerical analysis
Akpinar, Salih
In this study, mechanical properties of double-strap joints with aluminum or composite patches of different orientation angles at their overlap area were investigated under tensile loading. For this purpose, AA2024-T3 aluminum was used as adherend, while patches were either AA2024-T3 aluminum or 16-ply laminate of carbon/epoxy composite with five different orientation angles ([0]16, [90]16, [0/90]8, [45/-45]8, [0/45/-45/90]4). A two-part paste adhesive (DP 460) was used to bond adherend and patches. Six different types of joint samples were subjected to tensile loading. The effect of patch material on failure load and stress distribution was examined experimentally and numerically. As a result, it was concluded that the data obtained from 3-D finite element analysis were coherent with experimental results and additional to that fiber orientation angles of the patches markedly affected the failure load of joints, failure mode and stress distributions appeared in adhesive and composite.
- MakaleYalnız künye2013Evaluation of wind energy potentiality at coastal locations along the north eastern coasts of Turkey
Akpinar, Adem
This study aims to determine and evaluate wind energy potentiality along coastal locations at the North Eastern of Turkey. For this purpose, the present study has statistically analysed wind power potentials and wind characteristics from six meteorological stations (Sinop, Samsun, Ordu, Giresun, Trabzon, and Hopa) along the North Eastern (NE) geo-political coastal region of Turkey using the hourly or 3-hourly wind speed data measured at 10 m height during 9 years. The diurnal, monthly, and seasonal mean wind speed and wind power density at all the stations are assessed to have remarkable variations. The annual and seasonal frequency distributions and dominant wind directions of the all locations are determined. It is observed that the monthly mean wind speed in this region ranges from 1.53 m/s to 4.06 m/s. The maximum annual mean wind power density was found to be 59.96 W/m2 at Sinop while the maximum annual mean wind energy density was obtained to be 525.25 kWh/m2/year at the same station. It is further shown that Sinop, Hopa, and Trabzon have the higher wind power potential than other locations and their potential are close to each other.
- MakaleYalnız künye2013Effects of charge properties on exergy balance in spark ignition engines
Sezer, Ismet; Bilgin, Atilla
This study investigates the effects of the air-fuel mixture (charge) properties on the exergy balance in spark ignition engines. A thermodynamic cycle model including compression, combustion and expansion processes is used. The principles of the second law are applied to the cycle model to perform an exergy analysis. Variation of the exergetic variables during the investigated portion of the cycle are examined as a function of the charge properties, i.e., fuel-air equivalence ratio, residual gas fraction and initial charge temperature. The results show that increasing fuel-air equivalence ratio causes an increase in irreversibilities and also exergy losses with heat transfer and exhaust gases, but enriching the air-fuel mixture beyond the stoichiometric ratio makes no significant contribution to the exergy transfer with work transfer. A slightly lean mixture also gives the best first and second law efficiencies. It is observed that there is a linear relation between the residual gas fraction and the exergetic variables. An increase in the residual gas fraction decreases the irreversibilities and exergy losses aside from the exergy transfer with work transfer. However, increasing the residual gas fraction positively affects the first and second law efficiencies because of the diluting of the charge. Increase of initial charge temperature creates a reduction in the irreversibilities and the exergy losses and, it also results in a lower exergy output by work transfer. Further, increase of initial charge temperature negatively influences the first and second law efficiencies.
- MakaleYalnız künye2013Assessment of wave energy resource of the Black Sea based on 15-year numerical hindcast data
Akpinar, Adem; Kömürcü, Murat I.hsan
In this study, the existence and variability of wave energy resource potential of the Black Sea based on 15-year hindcast data is described in detail. The hindcasts of wave parameters were carried out by using the third generation wave prediction model (Simulated WAves Nearshore - SWAN), which is one of the most popular numerical wave models and has been widely used for estimating ocean waves. The model was forced with the ECMWF ERA Interim wind fields and applied with a spatial resolution of about 0.0167°. ×. 0.0167° and a model time step of 6. h to resolve efficiently offshore and nearshore wave conditions. The results were presented in the form of charts of the spatial distribution of significant wave height and wave power, on a monthly, seasonal and annual basis. Annual energy was calculated in the study region with the hindcast data set covering 15. years (1995-2009). The areas with the highest wave energy resource were determined and the south west coasts of the Black Sea are suggested as the best site for the installation of a wave farm. It was determined the western parts of the Black Sea (especially the south-west) are exposed to energetic waves more than the eastern parts.
- MakaleYalnız künye2012Wave energy potential along the south-east coasts of the Black Sea
Akpinar, Adem; Kömürcü, Murat Ihsan
This study aims to assess and characterize wave energy resource along the southeastern coasts of the Black Sea. For this purpose, wave energy potential was investigated at a total of 7 study points in this area. The potential for energy generation was assessed based on six-hourly data from a third generation wave model (SWAN) covering the period 1995-2009. The results were validated with buoy measurements and wave energy and power was calculated with the numerical hindcast data. For characterization of wave energy potential, average annual and seasonal variations of the wave power in this area was firstly investigated. Second, wave energy development indexes and the probabilities of exceedance of wave power at the study points were determined. Third, wave energy resource in different ranges of significant wave heights and zero-crossing periods were characterized. Finally, It was found that annual wave energy of all points except Sinop point, whose annual wave energy is 10 MWh/m, is approximately 6 MWh/m and the bulk of annual wave energy occurs for significant wave heights between 0.5 and 2 m and periods between 2 and 5 s.
- MakaleYalnız künye2011Modeling and forecasting of Turkey's energy consumption using socio-economic and demographic variables
Kankal, Murat; Akpinar, Adem; Kömürcü, Murat Ihsan; Özşahin, Talat Şükrü
This study deals with the modeling of the energy consumption in Turkey in order to forecast future projections based on socio-economic and demographic variables (gross domestic product-GDP, population, import and export amounts, and employment) using artificial neural network (ANN) and regression analyses. For this purpose, four diverse models including different indicators were used in the analyses. As the result of the analyses, this research proposes Model 2 as a suitable ANN model (having four independent variables being GDP, population, the amount of import and export) to efficiently estimate the energy consumption for Turkey. The proposed model predicted the energy consumption better than the regression models and the other three ANN models. Thus, the future energy consumption of Turkey is calculated by means of this model under different scenarios. The predicted forecast results by ANN were compared with the official forecasts. Finally, it was concluded that all the scenarios that were analyzed gave lower estimates of the energy consumption than the MENR projections and these scenarios also showed that the future energy consumption of Turkey would vary between 117.0 and 175.4. Mtoe in 2014.
- MakaleYalnız künye2009Frequency optimization of laminated skew plates
Topal, U.; Uzman, Ü.
In this study, the frequency optimization of laminated skew plates is investigated. The objective function is to maximize the fundamental frequency of the laminated skew plates and the fiber orientation is considered as design variable. The mathematical formulation is based on the first-order shear deformation theory (FSDT) for the frequency analysis of the laminated skew plates. The modified feasible direction (MFD) method is combined with the finite element solution of laminated skew plates for optimal designs. Therefore, a program based on FORTRAN is used. Finally, the effect of skew angles, boundary conditions, aspect ratios and functionally graded materials on the optimal results is investigated and the results are compared.
- MakaleYalnız künye2008Frequency optimization of laminated composite angle-ply plates with circular hole
Topal, U.; Uzman, Ü.
The fundamental frequencies of simply supported symmetrically laminated composite angle-ply plates with central circular holes with a given material system are maximized with respect to fibre orientations. The first-order shear deformation (FSDT) theory is used for finite element analysis. Modified feasible direction (MFD) method is used for the optimization routine. Also, the optimum fibre orientations are obtained using golden section (GS) method to compare with MFD method. Finally, the significant effects of different number of layers, boundary conditions, plate aspect ratios, hole diameter-to-width ratio, material anisotropy and antisymmetric lay-up on the results are demonstrated.
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