Use of vegetable oils as dielectric fluids for electrical discharge machining. A case study.

Electrical discharge machining with solid electrodes represents an efficient solution to generate blind cavities with complex geometry. Vegetable oils represent an alternative to conventional dielectrics, which are considered harmful for the environment and human health. This study tested the feasibility of two widely used vegetable oils, sunflower and soybean, under intense machining of three alloys with application in aeronautic industry, aiming for high process productivity and a good surface quality. The results have revealed that vegetable oils are capable to ensure an improvement of the material removal rates that can reach up to 55.15 % compared to mineral oil. Also, the vegetable dielectrics allowed an improvement of surface quality for non-ferrous alloys, up to a maximum of 19.70 %, whereas for the stainless steel, the mineral oil has provided a better surface finish.

Erratum: Radu, M.-C., et al. The Impact of the COVID-19 Pandemic on the Quality of Educational Process: A Student Survey. Int. J. Environ. Res. Public Health 2020, 17, 7770.

In the original version of our article [...].

The Impact of the COVID-19 Pandemic on the Quality of Educational Process: A Student Survey.

The paper presents the results of a students' survey carried out at "Vasile Alecsandri" University of Bacau, Romania, on the quality of educational process on online platforms in the context of the COVID-19 pandemic. The study was addressed to students from the Faculty of Engineering and the Faculty of Physical Education and Sports. The results of survey highlighted that most of students were satisfied with the measures taken by the university during the lockdown period and the way the teaching-learning-assessment process took place. However, some negative aspects were reported as: lack of an adequate infrastructure for some students, less effective teacher-student communication and interaction, impossibility of performing practical applications, lack of socialization, lack of learning motivation, less objective examination (e.g., possibility of cheating), possibility of physical and mental health degradation (e.g., too much time spent in front of screens, installation of a sedentary lifestyle). Consequently, for the new academic year, effective, and efficient measures must be implemented by the management of the university to remove, as much as possible, these negative issues and to improve the performance of online educational process.