Abstract
Due to its availability and low cost, the use of wireless communication technologies increases in domains beyond the originally intended usage areas, e.g. M2M communication in industrial applications. Such industrial applications often have specific security requirements. Hence, it is important to understand the characteristics of such applications and evaluate the vulnerabilities bearing the highest risk in this context. We present a comprehensive overview of security issues and features in existing WLAN, NFC and ZigBee standards, investigating the usage characteristics of these standards in industrial environments. We apply standard risk assessment methods to identify vulnerabilities with the highest risk across multiple technologies. We present a threat catalogue, conclude in which direction new mitigation methods should progress and how security analysis methods should be extended to meet requirements in the M2M domain.

Abstract
Support for multiple concurrent applications is an important enabler for promoting the use of sensor networks as an infrastructure technology, where multiple users can deploy their applications independently. In such a scenario, different applications on a node may transmit packets at distinct periods, causing the node to change from sleep to active state more often, which negatively impacts the energy consumption of the whole network. In this paper, we propose to batch the transmissions together by defining a harmonizing period to align the transmissions from multiple applications at periodic boundaries. This harmonizing period is then leveraged to design a protocol that coordinates the transmissions across nodes and provides real-time guarantees in a multi-hop network. This protocol, which we call Network-Harmonized Scheduling (NHS), takes advantage of the periodicity introduced to assign offsets to nodes at different hop-levels such that collisions are always avoided, and deterministic behavior is enforced. NHS is a light-weight and distributed protocol that does not require any global state-keeping mechanism. We implemented NHS on the Contiki operating system and show how it can achieve a duty-cycle comparable to an ideal TDMA approach.

Abstract
While Cluster-Tree network topologies look promising for WSN applications with timeliness and energy-efficiency requirements, we are yet to witness its adoption in commercial and academic solutions. One of the arguments that hinder the use of these topologies concerns the lack of flexibility in adapting to changes in the network, such as in traffic flows. This paper presents a solution to enable these networks with the ability to self-adapt their clusters' duty-cycle and scheduling, to provide increased quality of service to multiple traffic flows. Importantly, our approach enables a network to change its cluster scheduling without requiring long inaccessibility times or the re-association of the nodes. We show how to apply our methodology to the case of IEEE 802.15.4/ZigBee cluster-tree WSNs without significant changes to the protocol. Finally, we analyze and demonstrate the validity of our methodology through a comprehensive simulation and experimental validation using commercially available technology on a Structural Health Monitoring application scenario.

Abstract
Several concurrent applications running on a sensor network may cause a node to transmit packets at distinct periods, which increases the radio-switching rate and has significant impact in terms of the overall energy consumption. We propose to batch the transmissions together by defining a harmonizing period to align the transmissions from multiple applications at periodic boundaries. This harmonizing period is then leveraged to design a distributed protocol called Network-Harmonized Scheduling (NHS) that coordinates transmissions across nodes and provides real-time guarantees in a multi-hop network. Categories and Subject Descriptors-C. 3 [Computer Systems Organization]: Special-purpose and Application-Based Systems: Real-time and embedded systems

Abstract

Abstract
Context. FU Orionis objects are a class of young stars with powerful bursts in luminosity that show evidence of accretion and ejection activity. It is generally accepted that they are surrounded by a Keplerian circumstellar disk and an infalling envelope. The outburst occurs because of a sudden increase in the accretion rate. Aims. We study the regions closer to the central star in order to observe the signs of the accretion and ejection activity. Methods. We present optical observations of the Ha line using the Integral Field Spectrograph OASIS, at the William Herschel Telescope, combined with adaptive optics. Since this technique gives the spectral information for both spatial directions, we carried out a two-dimensional spectro-astrometric study of the signal. Results. We measured a clear spectro-astrometric signal in the north-south direction. The cross-correlation between the spectra showed a spatial distribution in velocity suggestive of scattering by a disk surrounding the star. This would be one of the few spatial inferences of a disk observed in an FU Orionis object. However, to fully understand the observed structure, higher angular and spectral resolution observations are required. V1515 Cyg now appears to be an important object to be observed with a new generation of instruments to increase our knowledge about the disk and outflow structure in FU Orionis objects.