Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 3Citation - Scopus: 3Enhancement of Filament Wound Glass Fiber/Epoxy-based Cylindrical Composites by Toughening With Single-Walled Carbon Nanotubes(SAGE Publications, 2022) Ay Solak, Zeynep; Kartav, Osman; Tanoğlu, MetinIn this study, the effect of incorporating nano-sized fillers (noncovalently functionalized with ethoxylated alcohol chemical-vapor-deposition-grown SWCNTs) within an epoxy resin on the performance of filament wound glass fiber (GF)-based cylindrical composites (GFCCs) was investigated. For this purpose, SWCNTs were dispersed with the concentration of 0.05 and 0.1 weight percent (wt.%) within an epoxy resin using mechanical stirring and calendaring (3-roll-milling) techniques. The rheological behavior of the SWCNT incorporated epoxy mixture was characterized to determine the suitability of blends for the filament winding process. It was revealed that the viscosity value of the resin was not significantly affected by the addition of SWCNTs in given concentrations. Moreover, contact angle measurements were also performed on the SWCNT/epoxy blends dropped on the GF for the evaluation of the wettability behavior of the GF in the presence of the SWCNTs in relevant concentrations. Eventually, it was observed that the wettability behavior of GF was not reasonably affected by the presence of the SWCNTs. The double cantilever beam (DCB), flexural, and short beam shear (SBS) tests were performed on the reference and SWCNT-modified GFCC specimens to evaluate the effects of the SWCNT presence on the interlaminar fracture toughness and out-of-plane properties of GFCCs. The fractured surfaces after the DCB and SBS tests were analyzed under the scanning electron microscopy to reveal the toughening mechanisms and the filler morphologies. Consequently, although SWCNT incorporation was on the outermost layer of GFCCs, it was found that the interlaminar shear strength (ILSS) values and Mode I interlaminar fracture toughness values of the curved composite samples were improved up to 22 and 216%, respectively, due to the presence of the SWCNTs.Article Citation - WoS: 37Citation - Scopus: 41Determination of Olive Oil Adulteration With Vegetable Oils by Near Infrared Spectroscopy Coupled With Multivariate Calibration(SAGE Publications, 2010) Öztürk, Betül; Yalçın, Ayşegül; Özdemir, DurmuşThere has been growing public awareness about the health benefits of olive oil throughout the world in recent years, resulting in a significant increase in its consumption as part of the daily diet This demand has attracted fraudulent attempts to market olive oil which has been adulterated with cheaper oils. This study focuses on the near infrared (NIR) spectroscopic determination of adulteration of olive oil by vegetable oils using multivariate calibration. The binary, ternary and quaternary mixtures of olive, soybean, cotton, corn, canola and sunflower oils were prepared using a random design. The absorbance spectra of these synthetic samples were measured by a near infrared (NIR) spectrometer. A genetic algorithm-based variable selection algorithm, coupled with an inverse least squares multivariate calibration method (GILS) was used to build calibration models for possible adulterants and olive oil in the adulterated mixtures The correlation coefficients of actual versus predicted concentrations resulting from multivariate calibration models for the different oils were between 0 90 and 0.99 The results demonstrated that NIR spectroscopy in conjunction with the GILS method makes it possible to determine the adulteration of olive oils regardless of adulterant vegetable oils over a wide range of concentrations.Article Citation - WoS: 8Citation - Scopus: 9Dynamic Behavior Predictions of Fiber-Metal Laminate/Aluminum Foam Sandwiches Under Various Explosive Weights(SAGE Publications, 2016) Baştürk, Suat Bahar; Tanoğlu, Metin; Çankaya, Mehmet Alper; Eğilmez, Oğuz ÖzgürApplication of blast tests causes some problems to characterize the performance of panels due to the drastic conditions of explosive medium. Real test has high safety concerns and is not easily accessible because of its extra budget. Some approaches are needed for the preliminary predictions of dynamic characteristics of panels under blast loading conditions. In this study, the response of sandwiches under blast effect was evaluated by combining quasi-static experiments and computational blast test data. The primary aim is to relate the quasi-static panel analysis to dynamic blast load. Based on this idea, lightweight sandwich composites were subjected to quasi-static compression loading with a special test apparatus and the samples were assumed as single degree-of-freedom mass-spring systems to include dynamic effect. This approach provides a simpler way to simulate the blast loading over the surface of the panels and reveals the possible failure mechanisms without applying any explosives. Therefore the design of the panels can be revised by considering quasi-static test results. In this work, the peak deflections and survivabilities of sandwiches for various explosive weights were predicted based on the formulations reported in the literature. Major failure types were also identified and evaluated with respect to their thicknesses.Article Citation - WoS: 5Citation - Scopus: 7Public Personnel Management Process Capability Assessment(SAGE Publications, 2020) Gökalp, Ebru; Demirörs, Onur; Eren, P. ErhanPersonnel management plays a critical role in the success of public organizations. Our literature review shows that there is a lack of systematic guidance on how to improve Public Personnel Management Process (PPMP) quality. Software Process Improvement and Capability Determination (SPICE) is a process assessment framework that is successfully used by software organizations during the past two decades. The framework can also be used as a baseline to generate process capability models for different specific domains/sectors. We have utilized this approach for the government domain and we developed the process definition of PPMP. To observe the benefits and usability of the model, we have performed a multiple case study, including the assessments of three organizations' PPMP capability levels and the development of action plans for PPMP improvement. The findings show that the proposed approach is applicable for identifying the PPMP capability levels and is capable of providing a roadmap for moving to the next level.