Changes in the cross-country ski base properties resulting from the ski use

In this work, changes in the cross-country ski base properties resulting from stone grinding, skiing, waxing and re-stone grinding have been investigated. The surface topography, crystallinity, wettability and sliding properties of cross-country ski bases were recorded using a selection of measurement techniques: non-contact chromatic confocal microscopy, contact-type surface roughness analyser and scanning electron microscopy (topography), Raman spectroscopy (crystallinity), contact angle measurement (wettability) and a ski tester (sliding properties). The tested skis were used for 150 km and waxed 35 times. The ski base surface became smoother and the orientation and crystallisation of the base material increased. Wear decreased the hydrophobicity and increased the sliding friction. Even though re-grinding did not restore all of the ski base properties, re-grinding improved the wettability and sliding properties. The results help to optimise stone grinding interval to maintain the performance of the skis.     

On study habits on an introductory course on programming

Computer aided assessment systems enable the collection of exact time and date information on students’ activity on a course. These activity patterns reflect students’ study habits and these study habits further predict students’ likelihood to pass or fail a course. By identifying such patterns, those who design the courses can enforce positive study habits and to prevent or minimize habits that lead to poor student performance. Hypothetically, by identifying and adjusting the short-term patterns, the teachers might be able to do the same during the course. This publication examines students’ short-term study habits on an introductory level programming course and presents multiple statistically significant connections between students’ assignment submission patterns and their respective final grades. Students who receive the highest grade start and finish their work early, do not work on weekends, and do not work at night, whereas those who fail the course do not show similar behavior but exhibit significant enrichment among those who work large amounts during the night. Course’s mandatory tutorial sessions that act both as assignment release events and as collaborative assignment solving sessions strongly increase assignment submission counts regardless of the students’ final grades and ensure an early start to solving the assignments, possibly preventing those who would otherwise fail the course from starting their work near deadlines.