Aksaray University is a public higher educational institution established on March 17, 2006 in Aksaray, Central Anatolia in Turkey. Formerly it was a subunit of the Niğde University.The university has four faculties, two institutes, two colleges and five vocational colleges. Its campus is located on the highway to Adana. Wikipedia.
Sari M.,Aksaray University
Engineering Geology | Year: 2012
In this study, a special fitting technique is proposed to apply the Hoek-Brown failure criterion to available laboratory strength data collected on samples of Ankara andesites. The original method of fitting the Hoek-Brown failure criterion using the spreadsheet and the fitting method utilized in the RocLab software are statistically compared with this new modified nonlinear fitting technique. The Hoek-Brown failure parameters obtained by a simple multiple regression technique, utilizing the solver function within an Excel spreadsheet and the revised least squares procedure significantly improved the fitness of the Hoek-Brown envelope especially within the tensile and high confining stresses. The Brazilian tensile strength is found to be a useful parameter to fix a rock failure criterion at low confining stresses, particularly, in the tensile region. If tensile, uniaxial and triaxial test results are available, when compared to two existing fitting methods the modified multiple regression method is found to predict more precise tensile and compressive strengths, and material constant m i for the Hoek-Brown failure criterion. © 2011 Elsevier B.V.
Karatas M.,Aksaray University
Journal of Hazardous Materials | Year: 2012
The present study was aimed at examining the ability of a natural zeolitic volcanic tuff to remove Pb(II) ions from aqueous solutions under various conditions. The effects of various parameters such as optimum adsorbent mass, contact time, pH of the medium, Pb(II) concentration, and temperature were investigated. In addition, different adsorption isotherms were obtained using concentrations of Pb(II) ions ranging from 1. mg/L to 200. mg/L. The adsorption process follows second-order reaction kinetics and follows the Langmuir adsorption isotherm. The thermodynamic parameters are discussed in this article, including changes in Gibbs free energy, entropy, and enthalpy, for the adsorption of Pb(II) on tuff, and it is revealed that the adsorption process was spontaneous and exothermic under natural conditions. The maximum removal efficiency of 92% was obtained at a pH of 5 with a 25-min contact time for a 10. g/L solid-to-liquid ratio and an initial heavy metal concentration of 100. mg/L. © 2011 Elsevier B.V.
Yilmazturk F.,Aksaray University
Optics Express | Year: 2011
In photogrammetric applications, camera calibration and orientation procedures are a prerequisite for the extraction of precise and reliable 3D metric information from images. This study presents a method for full automatic calibration of color digital cameras using color targets. Software developed using Borland C + + Builder programming language is used to apply the method. With this software, the calibration process is carried out in 3 stages: firstly, at least four of six color targets (whose 3D object coordinates are known) on each image of the overall test field are detected and the approximate exterior orientation parameters are computed. Then, the remaining target points are measured using the approximate image locations, determined using these parameters and the 3D object point coordinates parameters. Finally, calibration parameters are determined using a self-calibration bundle adjustment technique. The colored targets within the test field are assigned labels corresponding to their color. For the detection of color targets and computation of approximate exterior orientation elements, HSV color space was used together with space resection computation method for all the possible color labels of targets. To test the proposed method, full automatic calibration was carried out using six different digital cameras. The calibration accuracies achieved in object space were within the range 0.006 to 0.030 mm; the accuracies achieved in image space were within the range 0.14 to 0.51 μm. © 2011 Optical Society of America.
Yalcin A.,Aksaray University
Applied Clay Science | Year: 2011
In the Trabzon province at the Eastern Black Sea region in Turkey, there are small and large landslides, especially following heavy rainfall periods in every year. These landslides regularly result in the loss of lives and properties. In this study, an assessment on the geotechnical characteristics of the areas where the landslides occur and the immediate vicinity were compared with the characteristics of non-landslides areas. A total of 50 landslides occurring in different locations were studied. As a result of the geotechnical investigations, the average of liquid limit values were between 49% and 69%, and the average plasticity index of the units ranged from 9% to 19% in the overlying materials in the landslide areas. Heavy rainfall exceeding boundary saturation of soils plays a critical role in causing landslides. According to the Unified Soil Classification System, the soils were "silts of high plasticity and silts, silty or clayey fine sands of low plasticity". 80% of the total landslides occurred within very high and completely weathered units of basalt, andesite, or pyroclastics, and intercalations of sandstone, clayey limestone and siltstone. This study shows that the shear strength parameters decreased with increasing moisture content and that the number of landslides increased in relation to the particle size distribution of the clay. © 2011 Elsevier B.V.
Kaya M.,Aksaray University
Applied Soft Computing Journal | Year: 2011
In this study, two new crossover operators in genetic algorithm are proposed; sequential and random mixed crossover. In the first stage, existing and developed crossover operators were applied to two benchmark problems, namely the reinforced concrete beam problem and the space truss problem. In the second stage, the developed crossover operators were applied to a deep beam problem and, a concrete mix design problem. The fittest values obtained using developed crossover operators were higher than those were obtained with existing crossover operator after 30,000 generations. Moreover, in developed crossover operators, the random mixed crossover yields higher fitness values than the existing crossover operators. © 2010 Elsevier B.V. All rights reserved.
Bayram F.,Aksaray University
Cold Regions Science and Technology | Year: 2012
Natural stones are generally used as building materials for construction and decoration. Determining the deteriorations of stones after freeze-thaw cycles is important subject for natural building stones used in cold regions exposed excessive freezing and thawing during the year. Freeze-thaw test is conducted for determining the deteriorations of stones due to freeze-thaw cycling. The percentage loss in uniaxial compression strength is an important parameter indicating these deteriorations. However, it is extremely laborious and time consuming tests. Because of this, predicting the percentage loss values in uniaxial compression strengths from intact rock properties was the purpose of this paper. Freeze-thaw tests were applied on nine limestone samples selected from different cold regions of Turkey. All of them except two samples were found to be suitable for use in cold regions. A statistical model was developed for predicting the percentage loss values in uniaxial compression strength from intact tests of impact strength, modulus of elasticity and water absorption. This model equation is very reliable (R 2=0.95) and can be very useful for predetermination of uniaxial compression strengths of limestones after freeze-thaw test without testing. © 2012 Elsevier B.V.
Balta M.T.,Aksaray University
Energy and Buildings | Year: 2012
This study deals with energy/exergy, exergy cost analyses and sustainability assessment of a low exergy heating system. In this study, an indoor sports hall with a volume of about 28,180 m3 and a floor area of 2366 m2 is considered as a case study. In this context, three different heating options are investigated, namely, (i) a conventional boiler, (ii) a condensing boiler and (iii) an air heat pump as driven by fuel-oil, natural gas and electricity, respectively. In this regard, an energy and exergy analysis is employed to assess their performances and compare them through energy and exergy efficiencies and sustainability index. Also, total exergy costs based on the considered systems with three different fuels are determined and compared with each other. Overall exergy efficiencies of the heating systems are found to be 2.10%, 2.33% and 2.42% while their corresponding sustainability index values of the analyzed cases are calculated to be 1.021, 1.024 and 1.025 for cases 1 through 3, respectively. Total exergy costs of the considered systems are obtained to be Ccase1 > Ccase3 > C case2. Based on the exergy cost analysis results, the most cost effective system is Case 2. © 2012 Elsevier B.V. All rights reserved.
Akdag U.,Aksaray University
International Communications in Heat and Mass Transfer | Year: 2010
In this study, the forced convection heat transfer around a discrete heater located in a channel subjected to laminar pulsating air flow is numerically investigated. Simulations are conducted for six different frequencies and three different amplitudes, while the Reynolds number (Re=125) and Prandtl number (Pr=0.71) remain constant for all cases. The impact of the important governing parameters such as the Womersley number (Wo) and the amplitude of flow pulsation (Ao) on heat transfer rate from discrete heaters is examined in detail. The instant velocity and temperature profiles are obtained to determine of the role of dimensionless parameters for pulsating flow. The numerical results show that thermal transport from the heater is greatly affected by the frequency and amplitude of the flow pulsation. The results given are dimensionless parameters. © 2010 Elsevier Ltd.
Sonmez M.,Aksaray University
Applied Soft Computing Journal | Year: 2011
The main goal of the structural optimization is to minimize the weight of structures while satisfying all design requirements imposed by design codes. In this paper, the Artificial Bee Colony algorithm with an adaptive penalty function approach (ABC-AP) is proposed to minimize the weight of truss structures. The ABC algorithm is swarm intelligence based optimization technique inspired by the intelligent foraging behavior of honeybees. Five truss examples with fixed-geometry and up to 200 elements were studied to verify that the ABC algorithm is an effective optimization algorithm in the creation of an optimal design for truss structures. The results of the ABC-AP compared with results of other optimization algorithms from the literature show that this algorithm is a powerful search and optimization technique for structural design. © 2010 Elsevier B.V. All rights reserved.
Kaya A.,Aksaray University
International Journal of Heat and Mass Transfer | Year: 2011
This study investigates mixed convection heat transfer about a vertical slender hollow cylinder in the buoyancy and conjugate heat transfer effects in the porous medium with high porosity. The non-similar solutions using the Keller box method are obtained. The wall conduction parameter p, the porous medium parameter k1, the Forchheimer parameter F and the Richardson number are the main parameters. For various values of these parameters the local skin friction and local heat transfer parameters are determined. The validity of the methodology is checked by comparing the results with those available in the open literature and a fairly good agreement is observed. Finally, it is determined that the local skin friction and the local heat transfer coefficients increase with an increase buoyancy parameter Ri, porous medium parameter k1, Forchheimer parameter F and decrease with conjugate heat transfer parameter p. © 2010 Published by Elsevier Ltd. All rights reserved.