Bjarne Schmidt

Teaching engineering dynamics by use of peer instruction supported by an audience response system

The use of electronic audience response systems in university teaching is currently increasing rapidly. This paper describes how a consistent use of peer instruction facilitated by an audience response system has been introduced in an introductory engineering dynamics course. Data are presented that reveal that this teaching style leads to an increased learning outcome, especially regarding the students’ conceptual understanding of the subject. Further results show that the students are very satisfied with the teaching style and they give high rankings on several parameters, which is important to the learning process. Finally, this study indicates that the use of clickers provides the students with a more critical and hence maybe a more realistic self-assessment of their academic outcome.

Evolution of lead precipitates in ion implanted aluminium

Abstract Aluminium-lead alloys are characterized by extremely low miscibility in the solid phase across the entire equilibrium phase diagram. Ion implantation of lead into aluminium at room temperature therefore results in spontaneous phase separation and formation of nm-size lead precipitates growing in topotactical alignment (epitaxy in three dimensions) with the aluminium matrix with a cube/cube orientation relationship. Transmission electron microscopy (TEM), Rutherford backscattering spectrometry (RBS) and channeling techniques were used to analyze the formation and evolution of lead precipitates during implantation and subsequent annealing. Implantations at room temperature induce a microstructure characterized by very small (2–5 nm) precipitates embedded in a heavily damaged matrix. Only ∼50% of the implanted lead atoms are retained in precipitates while the rest are in supersaturated solution or in small (