Greet Langie

DERIVATION OF LANDAU THEORIES AND LATTICE MEAN-FIELD THEORIES FOR SURFACE AND WETTING PHENOMENA, FROM SEMI-INFINITE ISING MODELS

Abstract The phenomenological aspects of surface and interfacial phenomena such as wetting phase transitions are commonly studied using the classification scheme provided by the Landau theory. Although this approach is very meaningful, it is also important to establish a firm connection between the phenomenology and the microscopic models of statistical mechanics. This is true, especially in view of the remarkable sensitivity of wetting phenomena to the details of the substrate-adsorbate interactions. We study such connections and derive a variety of lattice mean-field theories, which make a bridge between the Landau theory and the semi-infinite Ising model with a surface. We discuss standard mean-field approximations (MFA) and improvements thereof, renormalization group techniques, reaction-field approximations, and cluster variation methods. We pay special attention to the derivation of the newly introduced triplet surface field h 3 in the Landau theory for wetting.

Line tension near multicritical wetting transitions

The interface displacement model previously employed for calculating the line tension near first-order and critical wetting transitions is applied to multicritical wetting transitions. For short-range forces (with exponential decay) the line tension is negative in the partial wetting regime close to the multicritical point, and vanishes as the first power of the contact angle θ. For long-range forces (with algebraic decay) the vanishing of the line tension is qualitatively similar, but the power of θ is less than unity and depends both on the range of the forces and on the order of the multicriticality. Furthermore, the exponents characterizing the vanishing of the line tension, when approaching multicriticality along selected first-order wetting phase boundaries, are calculated for both short- and long-range forces.

Dashboard for Actionable Feedback on Learning Skills: Scalability and Usefulness

In the transition from secondary to higher education, students are expected to develop a set of learning skills. This paper reports on a dashboard implemented and designed to support this development, hereby bridging the gap between Learning Analytics research and the daily practice of supporting students. To demonstrate the scalability and usefulness of the dashboard, this paper reports on an intervention with 1406 first-year students in 12 different programs. The results show that the dashboard is perceived as clear and useful. While students not accessing the dashboard have lower learning skills, they make more use of the extra remediation possibilities in the dashboard.

Monte Carlo simulation study of the thicknesses of wetting layers in pure and impure (quenched random-field) environments

Wetting layer thicknesses have been measured in Monte Carlo simulations of a three-dimensional solid-on-solid model of adsorption. In a pure environment the average thickness l is found to follow the expected logarithmic law as a function of the undersaturation or bulk field hB. At small hB the results are consistent with a cross-over to a power law l ∞ h-1B, predicted on the basis of finite-size effects. In an impure quenched random-field environment a logarithmic law is found at relatively large hB, as for the pure system. When hB is lowered the simulations show pinning of the interface by the random fields, implying slowing down of the relaxation, strong dependence on the starting configuration, and strong sensitivity to the random-field environment. In addition to the cross-over due to the finite system size, these problems have made the expected power-law behaviour l ∝ h-12B inextricable.

Multi-institutional positioning test feedback dashboard for aspiring students: lessons learnt from a case study in flanders

Our work focuses on a multi-institutional implementation and evaluation of a Learning Analytics Dashboards (LAD) at scale, providing feedback to N=337 aspiring STEM (science, technology, engineering and mathematics) students participating in a region-wide positioning test before entering the study program. Study advisors were closely involved in the design and evaluation of the dashboard. The multi-institutional context of our case study requires careful consideration of external stakeholders and data ownership and portability issues, which gives shape to the technical design of the LAD. Our approach confirms students as active agents with data ownership, using an anonymous feedback code to access the LAD and to enable students to share their data with institutions at their discretion. Other distinguishing features of the LAD are the support for active content contribution by study advisors and LATEX type-setting of question item feedback to enhance visual recognizability. We present our lessons learnt from a first iteration in production.

Comparison between bridging students and traditional first-year students in engineering technology

ABSTRACT To stimulate a flexible lifelong learning system students can enter university via lateral entry. Unlike traditional first-year students, lateral entrance students are not well-studied. Therefore this study focuses on comparing first-year students with a specific group of lateral entrants, namely bridging students at the Faculty of Engineering Technology, KU Leuven. Using Astin’s Input-Environment-Outcome model resulted in (1) Input variables, namely prior education and initial learning and study strategies, (2) Environmental influence, measured with a questionnaire focussing on perceived transition to university, and (3) Outcome variables, namely dropout and academic achievement. Analyses resulted in similarities for the outcome variables, but differences in terms of secondary education. Regarding the input (LASSI) and environmental questionnaires, for only two of the 13 scales a moderate effect was found (perceived preparedness and test strategies). Consequently, research findings of first-year engineering students can be compared, taking into account their specific differences, to the context of bridging students.

Design and implementation of multi-campus, modular master classes in biochemical engineering

The Master of Science in engineering technology: biochemical engineering is organised in KU Leuven at four geographically dispersed campuses. To sustain the Masters programmes at all campuses, it is clear that a unique education profile at each campus is crucial. In addition, a rationalisation is required by increased cooperation, increased exchange of lecturers, and increased student mobility. To achieve this, a multicampus education system for the M.Sc. in engineering technology: biochemical engineering was developed by offering modules that are also available for students of other campuses. Such a module is primarily based on the research expertise present at the campus. In the development, special attention has been given to the optimal organisation of the modules, evaluation, required modifications of the current curricula, and the practical consequences for students following the module at another campus. Even in the first year of implementation, around 30% of the students followed a multicampus module, which indicates the potential success of the multicampus concept described here.