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Öğe Analysis of Yield Criteria and Flow Curves on FLC for TWIP900 Steel(Springer, 2020) Kilic, S.; Ozturk, F.; Toros, S.In this study, the applicability of yield criteria and flow curve models to predict forming limit curve (FLC) via the Marciniak-Kuczynski (M-K) model is investigated for TWIP900 steel. Forming limit characteristics of TWIP900 are determined experimentally and numerically. The yield criteria of Hill48, Barlat89, YLD2000-2d, and BBC2000 are tested and compared with each other. Results indicate that the YLD2000-2d and the BBC2000 yield criteria are found to be more accurate than the other criteria. The YLD2000 criterion has the best prediction capability with the Krupskowsky flow curve while the BBC2000 model has the best prediction with the Ludwick flow curve model.Öğe ASSESSMENT OF SPATIAL VARIABILITY OF SOIL PROPERTIES IN AREAS UNDER DIFFERENT LAND USE(SCIENTIFIC ISSUES NATL CENTRE AGRARIAN SCIENCES, 2012) Kilic, K.; Kilic, S.; Kocyigit, R.Land conversion from native ecosystem to agricultural use may alter soil physical, chemical and biological properties depending on duration and the type of tillage. The objectives of this study were to evaluate effects of duration of intensive cultivation practices (5 and 20 years cultivation) on some soil chemical and physical properties and to characterize spatial variability of soil properties. The study area is located at Kaz Lake of Tokat, Turkey. Soil pH, electrical conductivity (EC), cation exchange capacity (CEC), soil organic matter (SOM), total N, plant available P and soil texture were analyzed soil samples collected from a 5- and 20-year cultivated field converted from a native grassland. In addition, spatial variability of the soil properties under each land use were defined using statistical and geostatistical analysis. Soil pH had the minimum variability compared to other soil properties. Soil tillage (5 and 20 years of cultivations) caused significant changes in soil properties. Soil organic matter, total N, available P, CEC, and EC, clay content and silt content decreased significantly (p<0.01) while K, pH and sand content increased with cultivation. The range of spatial dependence is between 9.6 and 310 m. Soil variables with low nugget effect were defined by spherical model. The variables of the cultivated soils generally had a lower nugget than the variables of the native grassland. The degree of spatial dependence for CEC, clay, silt, sand and pH was low. The variation of the soil variables was fairly homogenized in the cultivated fields compared to the native grassland.Öğe Assessment of spatial variability of soil properties in areas under different land use(2012) Kilic, K.; Kilic, S.; Kocyigit, R.Land conversion from native ecosystem to agricultural use may alter soil physical, chemical and biological properties depending on duration and the type of tillage. The objectives of this study were to evaluate effects of duration of intensive cultivation practices (5 and 20 years cultivation) on some soil chemical and physical properties and to characterize spatial variability of soil properties. The study area is located at Kaz Lake of Tokat, Turkey. Soil pH, electrical conductivity (EC), cation exchange capacity (CEC), soil organic matter (SOM), total N, plant available P and soil texture were analyzed soil samples collected from a 5- and 20-year cultivated field converted from a native grassland. In addition, spatial variability of the soil properties under each land use were defined using statistical and geostatistical analysis. Soil pH had the minimum variability compared to other soil properties. Soil tillage (5 and 20 years of cultivations) caused significant changes in soil properties. Soil organic matter, total N, available P, CEC, and EC, clay content and silt content decreased significantly (p<0.01) while K+, Na+, pH and sand content increased with cultivation. The range of spatial dependence is between 9.6 and 310 m. Soil variables with low nugget effect were defined by spherical model. The variables of the cultivated soils generally had a lower nugget than the variables of the native grassland. The degree of spatial dependence for CEC, clay, silt, sand and pH was low. The variation of the soil variables was fairly homogenized in the cultivated fields compared to the native grassland.Öğe Coastal flood risk analysis using landsat-7 ETM+ imagery and SRTM DEM: A case study of Izmir, turkey(SPRINGER, 2007) Demirkesen, A. C.; Evrendilek, F.; Berberoglu, S.; Kilic, S.The Intergovernmental Panel on Climate Change (IPCC) reports an acceleration of the global mean sea-level rise (MSLR) in the twentieth century in response to global climate change. If this acceleration remains constant, then some coastal areas are most likely to be inundated by the year 2100. The ability to identify the differential vulnerability of coastlines to future inundation hazards as result of global climate change is necessary for timely actions to be taken. Yildiz et al. (Journal of Mapping, 17, 1 75, 2003) reported that the local MSLR in the city of Izmir rose at a rate of 6.8 +/- 0.9 mm year(-1) between 1984 and 2002. In this study, the spatial distribution of the coastal inundation hazards of Izmir region was determined using not only land-use and land-cover (LULC) types derived from the maximum likelihood classification of Landsat-7 Enhanced Thematic Mapper Plus (ETM+) multi-spectral image set but also the classification of the digital elevation model (DEM) acquired by the shuttle radar topography mission (SRTM). Coastal areas with elevations of 2 and 5 m above mean sea-level vulnerable to inundation were found to cover 2.1 and 3.7% of the study region (6,107 km(2)), respectively. Our findings revealed that Menemen plain along Gediz river, and the settlements of Karsiyaka, Alacati, Aliaga, Candarli and Selcuk are at high risk in order of decreasing vulnerability to permanent and episodic inundation by 2100 under the high MSLR scenarios of 20 to 50 mm year(-1).Öğe Effects of cold and warm temperatures on springback of aluminium-magnesium alloy 5083-H111(SAGE PUBLICATIONS LTD, 2009) Ozturk, F.; Toros, S.; Kilic, S.; Bas, M. H.Springback is one of the most common problems in sheet metal forming processes. It causes improper fit, which creates serious problems during assembly of the parts. Based on material strength, a considerable amount of elastic recovery during unloading can be observed. in this study, springback behaviour of a hardened 5083-H111 aluminium-magnesium (Al-Mg) alloy with a thickness of 3 mm using a 600 angle V-shape die bending process at various temperatures ranging from -50 to 300 degrees C was investigated. The effects of temperature on springback behaviour were identified. Results indicate that springback increased with decreasing temperature. The same amount of springback was measured at 0, 25, and 100 degrees C. It was observed that the amount of springback increased between 100 and 200 degrees C and then started to decrease beyond 200 degrees C. The lowest springback was obtained at 300 degrees C.Öğe Environmental monitoring of land-use and land-cover changes in amik plain, Turkey(International Society for Photogrammetry and Remote Sensing, 2004) Kilic, S.; Evrendilek, F.; Berberoglu, S.; Demirkesen, A.C.Unprecedented rates of changes in land use/cover (LULC) on the local and regional scales lead to alterations of global biogeochemical cycles, and loss of productive ecosystems and biodiversity. Driving forces behind LULC changes mainly include rapid growth rates of population and consumption, lack of valuation of ecological services, poverty, ignorance of biophysical limitations, and use of ecologically incompatible technologies. One of the major ecological tragedies of the commons in the province of Hatay is the case of the loss of the Amik Lake, which reveals the urgent need for adoption of sustainable and adaptive ecosystem management strategies if escalating land use conflicts are to be avoided and environmental degradation is to be reversed in the Amik plain of the southeastern Mediterranean region of Turkey. In the 1940s, the Amik lake was started to be discharged into the Orontes river by a large-scale campaign launched to increase the area of croplands. The study quantified LULC changes and explored constraints and opportunities for future LULCs in the study area. Land use/cover changes were detected from a time series of satellite images of Landsat-MSS in 1972, Landsat-5 TM in 1987, and Landsat-7 ETM+ in 2000 using remote sensing and geographic information systems (GIS). The study revealed that the increase in croplands between 1972 and 1987 took place at the expense of the irreversible losses of the Amik lake and its related wetlands of over 53 km2 used to provide vital ecosystem goods and services for the region. In the period of 1972 to 2000, croplands, settlements, and evergreen forests increased by 174%, 106%, and 14%, respectively, in parallel to the decreases in shrublands-orchards, and bareground. The increase in settlements occurred mostly to the detriment of croplands. The prospects for halting environmental degradation and destruction, rehabilitating damaged ecosystems, and developing sustainable ecosystem management practices need to be dealt with in light of the institutional and economic constraints facing Turkey.Öğe Influence of aging treatment on mechanical properties of 6061 aluminum alloy(ELSEVIER SCI LTD, 2010) Ozturk, F.; Sisman, A.; Toros, S.; Kilic, S.; Picu, R. C.Aluminum-magnesium-silicon (Al-Mg-Si) alloys show medium strength, excellent formability, good corrosion resistance and are widely used in extruded products and automotive body panels. The major advantage of these alloys is their age hardening response during the paint baking process as well as the fact that they exhibit no yield point phenomenon and Ludering. In this study, the mechanical properties of a commercially available AA6061 alloy aged to various levels were studied. Peak-aged conditions were reached in this particular alloy after a 2 h heat treatment at 200 degrees C. The variation of the yield stress, ultimate tensile strength, ductility and strain hardening rate with aging time is measured and discussed in relation to the microstructural changes induced by the heat treatment. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Seroprevalence of toxoplasmosis in horses in Nigde Province of Turkey(SPRINGER, 2010) Karatepe, B.; Babur, C.; Karatepe, M.; Kilic, S.The present study was conducted to investigate the prevalence of Toxoplasma gondii specific antibodies in local horses from four districts of Nigde in the middle of Turkey, between April-June 2004. Serum samples were obtained a total of 125 horses which consisted of 81 (50 female, 31 male) 1-10 years old and 44 (25 female, 19 male) 11-20 years old and tested for antibodies to T. gondii using the Sabin Feldman Dye Test (SFDT). According to the results of the SFDT, antibodies to T. gondii were found by the SFDT in 9 (7.2%) of 125 sera with the titers of 1:16 (8 horses) and 1:64 (1 horse). Antibodies to T. gondii were found in 6 (7.40%) of 81 horses (1-10 years old) and 3 (6.81%) of 44 horses (11-20 years old). From the 5 (10%) out of 50 male horses and the 4 (5.33%) out of 75 female horses were detected anti-T. gondii antibodies. No statistically significant difference in age groups (p > 0.01) and genders (p > 0.005) were observed between the seropositive and seronegative horses using the x(2) test. Seropositivity rates ranged from 2.85% to 11.42%, depending on the study sites. In regard to study sites, there was no statistically significant difference was found (p > 0.005). This is the first serological report on toxoplasmosis in horses from Nigde of Turkey.Öğe Tensile and Spring-Back Behavior of DP600 Advanced High Strength Steel at Warm Temperatures(SPRINGER, 2009) Ozturk, F.; Toros, S.; Kilic, S.In recent years, the use of advanced high strength steels in automotive industry has been increased remarkably. Among advanced high strength steels, dual phase (DP) steels have gained a great attention owing to a combination of high strength and good formability. However, high strength usually increases the spring-back behavior of the material, which creates problems for the parts during the assembly. Thus, the uniaxial tensile deformation and spring-back behaviors of DP600 advanced high strength steel were investigated in rolling (0 degrees), diagonal (45 degrees), and transverse (90 degrees) directions in the temperature range from room temperature (RT) to 300 degrees C. All tests were performed at a deformation speed of 25 mm/min. A V-shaped die (60 degrees) was used for the spring-back measurements. The results indicated that the formability and spring-back of the material were decreased with increasing the temperatures. The material showed complex behaviors in different directions and at different temperatures.
