Fermi and intramode relaxation phenomena in CO2lasers

Using a 1 ns pulse from a short-pulse CO2laser system, the evolution of the gain in a TEA system was studied during and after amplification. This resulted in a very direct observation of a few relaxation processes. We estimated the effective intramode relaxation rate constant to be larger than6 times 10^{6}torr-1/s. The Fermi relaxation time constant was found to be 30 ± 7 ns at 760 torr. We conclude that for nanosecond pulse amplification, intramode relaxation cannot be neglected

Demonstration projects of Nearly Zero Energy Buildings:Lessons from end-user experiences in Amsterdam, Helsingborg, and Lyon

Nearly Zero Energy Buildings (NZEBs) have been positioned as a low carbon strategy by the European Union in its Directive on the Energy Performance of Buildings (Directive 2010/31/EU). Underlying this directive is that the choice of technical options as well as sources of renewable energy may vary across EU countries and building projects. This article aims to compare the outcomes of NZEB demonstration projects in newly built city districts in Amsterdam, Helsingborg, and Lyon, using insights from strategic niche management theory combined with post-occupancy evaluation. More specifically, the analysis focuses on end-user expectations and experiences with living in energy-neutral city districts and homes, identifying lessons learned. A major conclusion is that the NZEB demonstration projects only facilitated single loop learning of end-users but did not provide an impetus for double loop learning. The findings suggest that NZEB projects need to be redesigned to facilitate more active roles of end-users in order to help realising their full potential in terms of increased energy efficiency and social learning