Angular velocity nonlinear observer from single vector measurements

The paper proposes a technique to estimate the angular velocity of a rigid body from single vector measurements. Compared to the approaches presented in the literature, it does not use attitude information nor rate gyros as inputs. Instead, vector measurements are directly filtered through a nonlinear observer estimating the angular velocity. Convergence is established using a detailed analysis of a linear-time varying dynamics appearing in the estimation error equation. This equation stems from the classic Euler equations and measurement equations. As is proven, the case of free-rotation allows one to relax the persistence of excitation assumption. Simulation results are provided to illustrate the method.Comment: 10 pages, 8 figures. arXiv admin note: substantial text overlap with arXiv:1503.0287

Regularity at space-like and null infinity

We extend Penrose's peeling model for the asymptotic behaviour of solutions to the scalar wave equation at null infinity on asymptotically flat backgrounds, which is well understood for flat space-time, to Schwarzschild and the asymptotically simple space-times of Corvino-Schoen/Chrusciel-Delay. We combine conformal techniques and vector field methods: a naive adaptation of the ``Morawetz vector field'' to a conformal rescaling of the Schwarzschild metric yields a complete scattering theory on Corvino-Schoen/Chrusciel-Delay space-times. A good classification of solutions that peel arises from the use of a null vector field that is transverse to null infinity to raise the regularity in the estimates. We obtain a new characterization of solutions admitting a peeling at a given order that is valid for both Schwarzschild and Minkowski space-times. On flat space-time, this allows large classes of solutions than the characterizations used since Penrose's work. Our results establish the validity of the peeling model at all orders for the scalar wave equation on the Schwarzschild metric and on the corresponding Corvino-Schoen/Chrusciel-Delay space-times

Impact of measurement dating inaccuracies in the monitoring of bulk material flows

This paper discusses the negative impact of errors in the dating of information gathered across a distributed network of sensors to be treated by a centralized monitoring algorithm. In this contribution, an example of flow monitoring serves as basis for the analysis. We consider an estimator setup for loss detection. Using a simple probability model, we determine the variance of this estimator and show how it is impacted by the dating uncertainty. A mitigating solution is proposed. Further extensions are discussed

Dynamic Deployment of Sensing Experiments in the Wild Using Smartphones

Part 1: Full Research PapersInternational audienceWhile scientific communities extensively exploit simulations to validate their theories, the relevance of their results strongly depends on the realism of the dataset they use as an input. This statement is particularly true when considering human activity traces, which tend to be highly unpredictable. In this paper, we therefore introduce APISENSE, a distributed crowdsensing platform for collecting realistic activity traces. In particular, APISENSE provides to scientists a participative platform to help them to easily deploy their sensing experiments in the wild. Beyond the scientific contributions of this platform, the technical originality of APISENSE lies in its Cloud orientation and the dynamic deployment of scripts within the mobile devices of the participants.We validate this platform by reporting on various crowdsensing experiments we deployed using Android smartphones and comparing our solution to existing crowdsensing platforms

Pushing the limits of CAN - scheduling frames with offsets provides a major performance boost

International audienceWith the increasing amount of electronics, making best usage of the bandwidth becomes of primary importance in automotive networks. One solution that is being investigated by car manufacturers is to schedule the messages with offsets, which leads to a desynchronization of the message streams. As it will be shown, this “traffic shaping” strategy is very beneficial in terms of worst-case response times. In this chapter, the problem of choosing the best offsets is addressed in the case of Controller Area Network, which is a de-facto standard in the automotive world. Comprehensive experiments shown in this chapter give insight into the fundamental reasons why offsets are efficient, and demonstrate that offsets actually provide a major performance boost in terms of response times. These experimental results suggest that sound off-set strategies may extend the lifespan of CAN further, and may defer the introduction of FlexRay and additional CAN networks

A model-based approach to assess the effectiveness of pest biocontrol by natural enemies

Main goal: The aim of this note is to propose a modeling approach for assessing the effectiveness of pest biocontrol by natural enemies in diversified agricultural landscapes including several pesticide-based management strategies. Our approach combines a stochastic landscape model with a spatially-explicit model of population dynamics. It enables us to analyze the effect of the landscape composition (proportion of semi-natural habitat, non-treated crops, slightly treated crops and conventionally treated crops) on the effectiveness of pest biocontrol. Effectiveness is measured through environmental and agronomical descriptors, measuring respectively the impact of the pesticides on the environment and the average agronomic productivity of the whole landscape taking into account losses caused by pests. Conclusions: The effectiveness of the pesticide, the intensity of the treatment and the pest intrinsic growth rate are found to be the main drivers of landscape productivity. The loss in productivity due to a reduced use of pesticide can be partly compensated by biocontrol. However, the model suggests that it is not possible to maintain a constant level of productivity while reducing the use of pesticides, even with highly efficient natural enemies. Fragmentation of the semi-natural habitats and increased crop rotation tend to slightly enhance the effectiveness of biocontrol but have a marginal effect compared to the predation rate by natural enemies. This note was written in the framework of the ANR project PEERLESS "Predictive Ecological Engineering for Landscape Ecosystem Services and Sustainability"(ANR-12-AGRO-0006)

Une plate-forme pour le test de cartes hybrides

National audienceNous présentons une méthode ainsi qu'une architecture et les premières briques d'une plate-forme pour le test de cartes hybrides. L'accent est mis sur la modélisation fonctionnelle des cartes et sur les stratégies de test fonctionnel développées pour le test en maintenance. Ces stratégies s'expriment en termes de contraintes et leur mise en œuvre repose sur la programmation logique par contraintes. Pour finir, nous évoquons une étude de cas industrielle, puis l'état d'avancement actuel de la plate-forme et ses évolutions futures sont discutées

Building a morphological and syntactic lexicon by merging various linguistic resources

Proceedings of the 17th Nordic Conference of Computational Linguistics NODALIDA 2009. Editors: Kristiina Jokinen and Eckhard Bick. NEALT Proceedings Series, Vol. 4 (2009), 126-133. © 2009 The editors and contributors. Published by Northern European Association for Language Technology (NEALT) http://omilia.uio.no/nealt . Electronically published at Tartu University Library (Estonia) http://hdl.handle.net/10062/9206