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Öğe Investigation of plasma arc cutting parameters with type-2 fuzzy set and system(De Gruyter, 2013-10) Çelik, Yahya Hışman; Özek, Cebeli; Bulut Özek, MüzeyyenThe objective of the present study was it to design a type-2 fuzzy set and system in order to predict surface roughness and hardness depending on the parameters (material thickness, cutting speed, arc voltage and current) of the plasma arc cutting process of S235JR sheet materials. Therefore, some experimental studies were conducted. The experimentally determined data were used to describe the type-2 fuzzy set and system. Type-2 fuzzy set and system was found to be usefull to predict surface roughnes and hardness. According to the obtained values, the best surface roughness and the values closest to the hardness of the raw material were obtained at 1500 mm/min cutting speed, 8 mm material thickness, 115 V arc voltage and 80 A current.Öğe Archaeozoological study of a unique Late Neolithic pitfrom Tepecik-Çiftlik, central Turkey(Anthropozoologica, 2019-08-16) Gündem, Can YumniThe absence of written evidence from prehistoric periods makes it difficult to understand the origins of sacrifice or offering ceremonies. Archaeological finds from prehistoric periods are the only solid evidence for these acts and rituals. One probable case of animal sacrifice or offering in the Neolithic period has been found at the site of Tepecik-Çiftlik Höyük in central Turkey. This study is focused on a single unique pit, which contained only animal bones and was found in an open space. The contents clearly indicate that this pit can not be interpreted simply as mixed kitchen garbage since an almost complete cattle skeleton as well as sixteen left front leg remains from sheep were placed in the pit after a social, or more specifically, ritual act. Similar pit with similar content was found neither in the close region to Tepecik-Çiftlik nor within Anatolia. The main aim of this study is to introduce a special archaeological find group, those were left after certain prehistoric activity.Öğe Organogels as novel carriers for dermal and topical drug delivery vehicles(Kimyagerler Derneği, 2017) Barış Cebe, Deniz; Çolak, Mehmet; Hoşgören, HalilÖğe Current density-voltage analyses and interface characterization in Ag/DNA/p-InP structures(American Institute of Physics, 2012-02-15) Güllü, Ömer; Pakma, Osman; Türüt, AbdülmecitThe current density-voltage (J-V) characteristics of Ag/DNA/p-InP metal-insulator-semiconductor (MIS) structures have been investigated in room temperature. We have observed that the Ag/DNA/p-InP structure shows an excellent rectifying behavior and that this structure increases the barrier height (φ b0). The main electrical parameters of these structures, such as ideality factor (n), barrier height, and average series resistance values were found to be 1.087, 0.726 eV, and 66.92Ω. This value of n was attributed to the presence of an interfacial insulator layer at the Ag/p-InP interface and the density of interface states (N ss) localized at the InP/DNA interface. The values of N ss localized at the InP/DNA interface were found at 0.675-E v in the 1.38 × 10 12 eV -1 cm -2.Öğe Optimization and evaluation of dry and minimum quantity lubricating methods on machinability of AISI 4140 using Taguchi design and ANOVA(SAGE Journals, 2020-07-05) Gürbüz, Hüseyin; Gönülaçar, Yunus EmreIn this work, it is aimed to study the effects of dry machining and minimum quantity lubrication application on machinability in turning AISI 4140 steel by utilizing different cutting parameters. Also, this study contains effects and optimization of cutting conditions (dry and minimum quantity lubricating), feed rate, and cutting speed on surface roughness (Ra) and main cutting forces (Fc) determined by employing the Taguchi method. At the end of experiments, it was established that compared to dry machining operations, minimum quantity lubricating significantly reduced cutting tool wear, while Fc and Ra decreased in general. Analyses of variance, regression analysis, signal-to-noise ratio, and orthogonal array were employed to analyze the effects and contributions of independent variables on dependent variables. The optimum levels of the dependent variables for reducing Fc and Ra using signal-to-noise rates were established. According to signal-to-noise ratios, minimum quantity lubricating had a more important effect on Fc and Ra than dry machining. The optimal conditions for Fc and Ra were at 0.16 mm/rev feed rate, 125 m/min cutting speed at minimum quantity lubricating. Analysis of variance results demonstrated that the feed rate is the most influential independent variable on Fc (93.976 %) and Ra (89.352 %). Validation test results exhibited that the Taguchi method and regression analysis were highly achieved methods in the optimization of independent variables for dependent variables. Taguchi optimization technique and regression analysis obtained from Fc (R2Tag. = 0.972 and R2Rag. = 0.997) and Ra (R2Tag. = 0.985 and R2Rag. = 0.996) measurements match really well with the experimental dataÖğe Effect of seawater on pin-loaded laminated composites(De Gruyter, 2018-01) Deniz, Mehmet Emin; Karakuzu, Ramazan; Kanlıoğlu, HalitThe aim of this study was to investigate the effect of seawater on bearing strength of glass-epoxy laminated composites. The ratio of the edge distance to pin diameter (E/D) was changed from 1 to 5 and that of the specimen width to pin diameter (W/D) was selected as 3 and 4 for this study. The hole of the specimen was subjected to a traction force induced by a pin. Laminated composite plates were manufactured at the Company Izoreel Composites. Tension tests were performed on pinned joint specimens with a stacking sequence of [0/90]3S. The specimens were immersed in seawater of the Aegean Sea having a salinity of about 3.5 wt.-% in a glass aquarium at laboratory for 1, 3, 6, 9 and 12 months. For each period of immersion time, failure modes and maximum failure loads of the specimens were found experimentally. The maximum reduction of the bearing strength was obtained as 38% for E/D = 3 and W/D = 3 due to the seawater effect.Öğe Repair of an aluminum plate with an elliptical hole using a composite patch(Carl Hanser Verlag, 2018-11-15) Ergün, Raşit Koray; Adin, Hamit; Şişman, Abdullah; Temiz, ŞemsettinIn this paper, the stress on axially loaded metal sheets with elliptical holes reinforced by a double-sided composite patch was analysed. The metal sheets with elliptical holes were subjected to axial loading, although no load was applied along the edges of the holes. The central elliptical holes on the metal plates had different diameters. The overlap distance of composite patches, which were adhesively bonded on each side, was of varied lengths. Elasto-plastic stress analyses were examined by means of the finite element method (FEM). The experimental results were compared with numerical results and a convergence rate of 92 % was achieved.Öğe Effect of Cu addition on porous NiTi SMAs produced by self-propagating high-temperature synthesis(De Gruyter, 2019-12) Batı, Serkan; Kılıç, Musa; Yenigün, Burak; Balaban, Zülküf; Kırık, İhsanThe focus of the study is on the effect of copper addition on the porosity, microstructure and mechanical properties of hot pressed NiTi and NiTiCu shape memory alloys (SMAs), ignited by means of self-propagating high-temperature synthesis (SHS). Optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), hardness tests and compression tests were applied respectively to determine the microstructure and mechanical behavior of the samples. The experimental results show that the addition of Cu into NiTi SMAs increases porosity and microhardness but also reduces compressive strength.Öğe Effects of specimen dimensions and impact energy on energy absorption and damage of glass/epoxy composite plates(De Gruyter, 2019-02-21) Deniz, Mehmet Emin; Karakuzu, Ramazan; Algan, BerkIn this study, the impact response of laminated composite plates of various specimen dimensions under various impact energies has been investigated, experimentally and numerically. Glass/epoxy composites with [02/902/02/902]s orientations were manufactured by the hand lay-up technique. Low velocity impact tests were conducted using a CEAST-Fractovis Plus impact test machine for specimens with net impact areas; SQR76 (square with 76 mm edge), SQR150 (square with 150 mm edge) and CIR76 (circle with diameter of 76 mm). Numerical analysis was also carried out via 3DIMPACT transient finite element code including matrix cracking and impact-induced delamination criteria. Absorbed energy and the damage size of specimens were investigated for various impact energies. Delamination areas obtained by finite element were in good agreement with those experimentally obtained up to 50 J of impact energy.Öğe Effect of matrix material and orientation angle on tensile and tribological behavior of jute reinforced composites(De Gruyter, 2019-07-27) Çelik, Yahya Hışman; Demir, Mehmet Emin; Kılıçkap, ErolEnvironmental friendly natural fibers have been used instead of petroleum-based synthetic fibers as reinforcements because of the depletion of oil resources, plastic waste disposal problems and the emissions generated during combustion. In these natural fibers, thermoplastic or thermoset materials are used as matrix material because of their low cost, light weight and durability. In this study, the effects of ply number (2 and 3 layer) and orientation angle of reinforcement (0/90° and ± 45°) and matrix type (thermoset and thermoplastic) on the tensile strength of jute reinforced composites were investigated. Also, the effect of the reinforcement orientation angle, sliding time (600, 1200 and 1800 s) and applied load (5, 10 and 15 N) on tribological characteristics were determined. Adhesive and abrasion wear tests were carried out at 0.15 m × s−1 sliding speed. It was observed that the matrix material and the reinforcement are very important in tensile and wear tests, while the ply number and the orientation angle only exert an influence in the tensile strength of composites. It was determined that an increase in load and sliding time is the most effective parameter on wear experiments.
