Clearing clouds of uncertainty

Market Clearing Mechanisms under Uncertainty

Electricity markets face a substantial amount of uncertainty. While traditionally this uncertainty has been due to varying demand, with the integration of larger proportions of volatile renewable energy, added uncertainty from generation must also be faced. Conventional electricity market designs cope with uncertainty by running two markets: a market that is cleared ahead of time, followed by a...

Simulation based uncertainty handling with polyhedral clouds

Past studies of uncertainty handling with polyhedral clouds have already shown strength in dealing with higher dimensional uncertainties in robust optimization, even in case of partial ignorance of statistical information. However, in thousands or more dimensions current implementations would still be computationally too expensive to be useful in real-life applications. In this paper we propose...

Single and Multisettlement Approaches to Market Clearing Under Demand Uncertainty

Unifying practical uncertainty representations. II: Clouds

There exist many tools for capturing imprecision in probabilistic representations. Among them are random sets, possibility distributions, probability intervals, and the more recents Ferson’s p-boxes and Neumaier’s clouds. Both for theoretical and practical considerations, it is very useful to know whether one representation can be turned into or approximated by other ones. In the companion pape...

Clearing up the clouds around NGC 4151 : evidence of a highly ionized absorber

The Seyfert 1 galaxy NGC 4151 is characterized by complex X-ray absorption, well described by a dual absorber, composed of a uniform mildly ionized gas and a cold system that partially covers the central source. However, in one of the 5 BeppoSAX observations, the spectrum shows two peculiar features. An absorption feature is detected around 8.5-9 keV with a statistical significance of 99.96%. T...