In this study, the influence of thermal radiation and dispersion on a porous medium which was filled in a vertical cylinder was numerically solved. A finite-difference method was used to solve the non-dimensional equations by applying a Crank-Nicolson implicit numerical technique. Moreover, an experimental set-up has been initially built to investigate the effect of three different grain sizes of the porous materials on the heat transfer process. The numerical results indicated that the thermal radiation increased the momentum and the thickness of the thermal boundary-layer during the natural-convection heat transfer process. Whereas, the thermal dispersion factor decreased the momentum and the thickness of the boundary-layer during the natural-convection heat transfer process, which enabled a steady and transient heat transfer. The experimental results indicated that the pore size of the medium significantly affected the rate of the heat transfer process. A smaller pore size showed a greater effect and could be used in different applications that involve a higher heat transfer rate, while a larger pore size can potentially be used as an insulating material.

Zamak 5 is a commercially important Zn–Al–Cu–Mg alloy that is frequently used in precision casting applications because of its dimensional stability, good casta-bility, and balanced engineering properties. In the present investigation, the in-fluence of two artificial aging conditions on the thermal and mechanical behavior of this alloy was experimentally examined. The first treatment consisted of aging at 85 °C for 44 h, whereas the second treatment was performed at 120 °C for 24 h. The aged specimens were characterized using SEM and EDS analyses together with microhardness testing and transient cooling experiments. The findings showed that aging reduced the hardness of the alloy relative to the untreated condition, with the largest reduction obtained after aging at 120 °C for 24 h. In contrast, the same condition produced the highest heat transfer response among the tested specimens. The thermal behavior was strongly associated with precip-itate evolution, redistribution of Zn-rich and Al-rich phases, and the resulting modification in thermal energy storage capability during transient cooling.

The COVID-19 pandemic has forced almost all universities in the world to switch from face-to-face to an online teaching format. In response to this sudden transition, the Mechanical Engineering department at the Al-Zaytoonah University in Jordan had to adapt to this change within two weeks in mid-March 2020. In addition, the department had to comply with the strict ABET accreditation regulations, among which is the indirect assessment of each course by the students each semester. They judge to what degree ABET-mandated student learning outcomes (SO) are actually met in any course designated to deliver the outcomes. Another ABET accreditation regulation is direct assessment, which is conducted by the instructor and relies on an instructor’s own evaluation of tasks designated for certain student learning outcomes. The aim of this study is to determine if, during the COVID-19 pandemic, students’ assessments changed significantly, in accordance with the ABET mandate, by using statistical analyses of students’ responses on an online completed survey. An independent samples t-test was used to evaluate the statistical importance of the observed differences. The SO coverage rates were quite high during the pandemic, although, generally, somewhat lower than their pre-pandemic equivalents. In this study, the Air Conditioning and Heating (ACH) course was selected to compare direct and indirect student learning outcomes before and after the COVID-19 pandemic. Consequently, our findings revealed a positive effect on SO performance during the COVID-19 pandemic and due to e-learning teaching.