Advanced NAno-Structured TapeS for electrotechnical high power Insulating Applications

The European ANASTASIA project is introduced, recalling the objective, rationale, and approaches driving its deployment. The application-driven context involves complex insulation systems consisting of mica tapes impregnated with epoxy resin. In view of the long-standing service experience of using such systems, the ANASTASIA consortium set out to enhance the present tape technology using nanodielectrics. This report focuses on the study of relevant and privileged fillers of nanometric dimensions and their effect in changing the macroscopic properties of their nanocomposites in the context of HV rotating machinery insulation. In view of the objective to explore the extent to nanostructuring can lead to material systems capable of withstanding increased design fields, with improved thermal conductivity and which attain class H, only breakdown behaviour, thermal conductivity and thermal degradation are considered here

Nano-structured Hybrid Sheets for Electrotechnical High-power Insulating Applications: The Sol-gel route

Among the new insulating materials to be used in high-voltage insulation, hybrid organic/inorganic nanocomposites have received a great attention. Indeed, these materials are gaining in popularity as an effective dielectric insulator with high temperature resistance. This research route is a part of the ANASTASIA consortium, which is made up of a balanced team of academic and industrial partners, and set out to address the wider topic of the reliable production of high performance nanodielectrics. Inorganic micro/nanofillers can be exploited for improving the breakdown strength, the dielectric permittivity and thermal conductivity of polymeric materials, using a sol-gel approach. Literature surveys identified some fillers as potential candidates for insulation applications. These sol-gel techniques show that all the hybrid systems present a structure based on amorphous metal-oxo nanodomains embedded within the polymer network. We further observed a strong influence of the cross-linking metal nature on the size of the metal-oxo nanoparticles and on the extent of the interface between inorganic domains and the polymer phase. Spectroscopic measurements revealed an important nanophase separation for the polymer systems incorporating for example Si(IV), Al(III), Ti(IV), or Zr(IV) alkoxides as cross-linking agents. Preliminary characterization has shown enhanced thermal conductivity and electrical performance for these nanostructured materials, compared with performance of current thermosets. Another advantage brought by this sol-gel technology is the wide choice of fillers and matrix compositions in order to design the mechanical, thermal and dielectric properties of the resulting nanocomposite. This paper will discuss the processes by which inorganic fillers are introduced and how the dielectric and thermal properties are thus improved

Creating Contexts for Collaborative Learning in a 3D Virtual World for Distance Education

The purpose of this chapter is to explore the contexts that teachers can create to promote collaborative learning in 3D virtual learning environments. The authors report on the findings of a case study using the 3D virtual world Second Life in a preservice teacher distance education program. Two types of contexts are identified: social interaction (social context) and instructor's scaffolding (pedagogical context). The anonymity represented by avatars in the 3D environment allowed learners to engage in social interaction and practice collaboration skills. Scaffolding involved several stages: scaffold the students' learning of the new technology, plan the course structure, implement the procedures during the lesson, and facilitate transitions between activities. The study also identifies the potential for a third context (emotional context), as the participants—both the instructor and the students—report a need to express emotions in many situations, but the environment does not seamlessly support this mode of communication