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Um Umweltprobleme zu lösen, müssen meist voneinander abgegrenzte Wissens systeme verbunden werden. Unterstützend wirkt ein funktionierender Wissensaustausch zwischen Forschung, öffent licher Verwaltung und Praxis. Spezifische Kompetenzen helfen, Wissensaus tauschprozesse erfolgreich zu gestalten; Kommunikationskompetenz ist eine davon.

Wireless sensor networks are ideally built on low-cost, low-complexity nodes that have a low power consumption to guarantee a long network lifetime. These are all properties that can potentially be achieved with impulse radio ultra-wide band (IR-UWB). In addition, IR-UWB has a fine timing resolution resulting in accurate ranging and localization possible. For all these reasons, IR-UWB is an extremely interesting physical layer technology for wireless sensor networks. In this article, we consider the management of impulsive interference in IR-UWB networks. Impulsive interference is due to uncoordinated concurrent transmissions. It occurs, for instance, when several independent piconets operate in close vicinity and is also present in some MAC layer proposals that allow concurrent transmissions. If not properly addressed, impulsive interference can severely affect the throughput and energy consumption of an IR-UWB network; as such, it already needs to be taken into account in the design phase. First, we show that impulsive interference is a serious concern for IR-UWB networks. Second, we present techniques at the physical layer and at the link layer to cope with and combat such interference efficiently. Finally, we present DCC-MAC as an example of an interference-aware design.

The present invention concerns a receiver and a method for retrieving data from Ultra wideband radio transmission signals received by a receiver and transmitted in packets containing at least a preamble known to the receiver and a payload containing data unknown to the receiver. The payload data is formed of at least one burst containing at least one pulse. The method comprises the steps of receiving a signal corresponding to the preamble of a packet by a receiver; determining the energy of the received signal; determining weighting coefficients from the energy of the received signal; receiving a signal corresponding to the payload of a packet by a receiver; determining the energy of the received signal; calculating a threshold depending on the weighting coefficients; and applying a decision rule based on the sampled energy, weighted by said weighting coefficients and depending on said calculated threshold.

Method for estimating and correcting a frequency offset between a local clock of a receiving transceiver and a remote clock of an emitting transceiver comprises receiving by said receiving transceiver, a signal emitted by the emitting transceiver, said signal lacking a continuous sinusoidal carrier and having at least one symbol, each symbol being emitted within a time frame having a first duration sampling the signal by taking for each time frame a set of energy measurements of said signal forming a matrix representative of said energy measurements determining from said energy matrix, points of maximum of energy within each time frame determining a line connecting a plurality of said points within each of said time frames determining a slope of said line calculating a frequency offset between the clocks of the emitting and receiving transceivers using the slope and adjusting the receiving transceiver's clock frequency according to the frequency offset.

International audience; The determination of endothelial cell density (ECD) is a crucial activity in eye banks for the assessment of corneal tissue quality. These cells are responsible for corneal transparency, and ECD correlates with graft survival. ECD is mainly assessed with a manual "naked-eye" procedure under a transmitted light microscope in Europe and using a specular microscope in the United States. Interbank and intrabank variability has been previously demonstrated. In order to facilitate training and continuing education of technicians and reliability assessment of eye banks' ECD determination, we use micro-optics technologies to fabricate test mosaics that exactly reproduce the image of human corneal endothelium. The description of the fabrication process is detailed, and comparisons are made between amplitude and phase mosaics.

International audience; A new rigorous vector-based design and analysis approach of diffractive lenses is presented. It combines the use of two methods: the Finite-Difference Time-Domain for the study in the near field, and the Radiation Spectrum Method for the propagation in the far field. This approach is proposed to design and optimize effective medium cylindrical diffractive lenses for high efficiency structured light illumination systems. These lenses are realised with binary subwavelength features that cannot be designed using the standard scalar theory. Furthermore, because of their finite and high frequencies characteristics, such devices prevent the use of coupled wave theory. The proposed approach is presented to determine the angular tolerance in the cases of binary subwavelength cylindrical lenses by calculating the diffraction efficiency as a function of the incidence angle.