Net-zero multi-energy systems for Siberian rural communities: A methodology to size thermal and electric storage units

About 15 million people live in rural communities in the Russian Federation. Most of them are not energetically supplied from the main national infrastructures (electric and gas). People living in such isolated communities use diesel engines for generating electricity and heat. In many cases, diesel is supplied using rail tracks, boats or even helicopters. Consequently, the generation of electricity has very high costs and very low reliability. For this reason, more and more rural isolated communities are using renewable energy sources to decrease their dependency on diesel sources. This study deals with the concept of net-zero multi-energy systems in rural and stand-alone areas. A methodology, based on economical, ecological, technical and social criteria, has been developed for planning the generation capacity and sizing the energy storage units. In addition, controlling algorithms have been developed to deal with the volatility of renewable energy sources (wind and sun) and integrate heat/electricity energy systems. The proposed methodology has been applied to the design of a net-zero energy system for a Siberian rural energy community

Coronagraphic search for wide substellar companions among members of the Ursa Major moving group

Context. We present the results of a survey to detect low-mass companions of Ursa Major (UMa) group members, carried out in 2003–2006 with NACO at the ESO VLT. While many extra-solar planets and planetary candidates have been found in close orbits around stars by the radial velocity and the transit methods, direct detections at wider orbits are rare. The UMa group, a young nearby stellar association at an age of about 200–600 Myr, has not yet been addressed as a whole although its members represent a very interesting sample to search for and characterize substellar companions by direct imaging. Aims. Our goal was to find or to provide detection limits on wide substellar companions around nearby UMa group members using high-resolution imaging. Methods. We searched for faint companions around 20 UMa group members within 30 pc. The primaries were placed below a semi-transparent coronagraph, a rarely used mode of NACO, to increase the dynamic range of the images. In most cases, second epoch images of companion candidates were taken to check whether they share common proper motion with the primary. Results. Our coronagraphic images rule out substellar companions around the stars of the sample. A typical dynamical range of 13–15 mag in the Ks band was achieved at separations beyond 3′′ from the star. Candidates as faint as Ks ≈ 20 were securely identified and measured. The survey is most sensitive between separations of 100 and 200 au but only on average because of the very different target distance. Field coverage reaches about 650 au for the most distant targets. Most of the 200 candidates detected in the covered fields are visible in two epochs and were rejected because they are distant background objects

“Let’s Wait and See!” The Real Option to Switch as a Value Component of Customer Relationships

Contains fulltext : 112218.pdf (publisher's version ) (Open Access)We suggest that a customer’s option to switch suppliers, and to wait and see before switching, adds to customer value in uncertain markets, and affects the customer’s switching behavior. We use a real options model to examine the value of this option and conduct sensitivity analyses based on data collected from the German public health insurance market to support our argument. We elaborate on the customer value construct and show how it contributes to customers’ behavioral loyalty. We also provide guidelines for managers of in-suppliers and out-suppliers on how to use the value of customers’ option to switch, e.g., for pricing decisions and management of customer churn.25 p