Railway ballast performance: Recent advances in the understanding of geometry, distribution and degradation

Railway ballast performance is dictated by a complex mix of mechanical properties. These effect its performance at the particle level for example in terms of particle degradation, but also at the track system level in terms of settlement and stability. Therefore this paper seeks to develop new understandings of ballast behaviour and identify...

Positron Annihilation Studies on Thin Film Solar Cells: CdSe and PbSe Quantum Dot Thin Films and Cu(In1-xGax)Se2 Layered Systems

High efficiency, low cost, and long stability are three key factors for the wide application of photovoltaics (PV) which are currently intensively studied in order to meet the increasing global renewable energy demand. Currently, the PV market is mainly based on silicon. However, solar cells based on silicon may not be capable to meet the long...