Massive Open Online Courses (MOOCs) in Turkey and an Analysis in the Context of Turkish Higher Education

Open and distance learning has evolved on the basis of openness philosophy in education and benefited from various approaches to this philosophy. Different MOOC platforms have emerged in Turkey as a reflection of these developments. The main purpose of this study is to examine MOOCs in the context of Turkish higher education. For this purpose, by adopting the qualitative embedded single case design, the Akadema, AtademiX and Bilgeİş MOOC platforms were examined. The findings indicate that MOOCs successfully serve the universal ideals such as offering equal opportunities in education, democratization of education, and liberation of knowledge in Turkey. Besides, MOOCs were found to contribute to adapting to the changes paralleling the transformations in the globalizing world and in the digital knowledge age; strengthening communication and cooperation channels between the society, industry and university; and finally, fostering social justice with an inclusive approach by increasing operational capabilities in diverse educational domains.

Effect of Pre-Stretch on the Precipitation Behavior and the Mechanical Properties of 2219 Al Alloy

The influence of pre-stretch on the mechanical properties of 2219 Al alloys sheets were systematically investigated, with the aim of examining the age-strengthening in parts draw-formed from as-quenched sheets. The precipitation was characterized based on differential scanning calorimetry (DSC) analysis and transmission electron microscope (TEM) observation of specimens of as-quenched and quenched-stretched condition to address the influence of pre-stretching. A tensile test was performed to evaluate the effect on mechanical properties. The introduction of pre-stretching endues increased yield strength (YS) and thus can be helpful to exert the potential of the alloy. Peak YS of 387.5 and 376.8 MPa are obtained when specimens pre-stretched for 10% are aged at 150 and 170 °C, respectively, much higher than that obtained in the non-stretched specimens (319.2 MPa). The precipitation of Guinier-Preston zone (G.P. zones) and the transition to θ″ shifts to a lower temperature when pre-stretched is performed. The high density of dislocations developed during the stretching contributes to the acceleration in precipitation. Quench-stretched specimens present a much quicker age-hardening response at the beginning stage, which endue higher peaked yield strength. The yield strength, however, decrease much more quickly due to the recovery that occurs during the aging processes. The study suggested the feasibility of aging draw-formed components of 2219 Al alloy to obtain high strength.

Quantification and Modelling of the Multiphase-Coupled Strengthening Effect in Al-Cu-Li Alloy

After aging heat treatment, Al-Cu-Li alloy, in general, contains a variety of precipitated phases that jointly influence the age-strengthening effect on the alloy. In this work, a multiphase-coupled strengthening model has been established on the basis of a dislocation bypassing mechanism. The model considered situations with different proportions of two strengthening phases, T1 and θ′, and then obtained the dimension and volume fractions of these two strengthening phases via experiments. The values predicted by the multiphase-coupled strengthening model and the classical strengthening superposition model were compared with the measured results. The multiphase-coupled strengthening model established in this work had better consistency with the measured results. Moreover, the modeling method proposed in the paper can also be extended to the system having over two primary strengthening phases. Hence, the model can contribute towards the development of a multi-component precipitation strengthening process for aluminum alloys.