5,973 research outputs found

    Grushin problems and control theory: Formulation and examples

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    In this paper we give a new formulation of an abstract control problem in terms of a Grushin problem, so that we will reformulate all notions of controllability, observability and stability in a new form that gives readers an easy interpretation of these notions

    Stability of higher order singular points of Poisson manifolds and Lie algebroids

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    We study the stability of singular points for smooth Poisson structures as well as general Lie algebroids. We give sufficient conditions for stability lying on the first (not necessarily linear) approximation of the given Poisson structure or Lie algebroid at a singular point. The main tools used here are the classical Lichnerowicz-Poisson cohomology and the deformation cohomology for Lie algebroids recently introduced by Crainic and Moerdijk. We also provide several examples of stable singular points of order k1k \geq 1 for Poisson structures and Lie algebroids. Finally, we apply our results to pre-symplectic leaves of Dirac manifolds.Comment: corrected typo

    On the local structure of Dirac manifolds

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    We give a local normal form for Dirac structures. As a consequence, we show that the dimensions of the pre-symplectic leaves of a Dirac manifold have the same parity. We also show that, given a point mm of a Dirac manifold MM, there is a well-defined transverse Poisson structure to the pre-symplectic leaf PP through mm. Finally, we describe the neighborhood of a pre-symplectic leaf in terms of geometric data. This description agrees with that given by Vorobjev for the Poisson caseComment: minor correction

    Optimization of blasting parameters in open cast quarries of El Hassa-Bouira (Northern Algeria)

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    In recent years, Algeria has known a rapid growth in the construction projects, such as: buildings, roads, and infrastructure, which increased the demand for aggregates production in quarries. However, vibrations and noises generated by blasting operations have a negative impact on the residents living nearby. For this reason, blast tests were performed in the open cast quarries of the company Sarl El Hassa-Bouira (Northern Algeria) using instantaneous electric detonators (IED), micro delays (MDD) and delays (EDD) to minimize the instantaneous load. We also minimized noise and vibration during the blasting. A seismograph allowed us to take further measurements

    VB-Courant algebroids, E-Courant algebroids and generalized geometry

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    In this paper, we first discuss the relation between VB-Courant algebroids and E-Courant algebroids and construct some examples of E-Courant algebroids. Then we introduce the notion of a generalized complex structure on an E-Courant algebroid, unifying the usual generalized complex structures on even-dimensional manifolds and generalized contact structures on odd-dimensional manifolds. Moreover, we study generalized complex structures on an omni-Lie algebroid in detail. In particular, we show that generalized complex structures on an omni-Lie algebra \gl(V)\oplus V correspond to complex Lie algebra structures on V.Comment: 19 page

    A Reinforcement Learning-driven Translation Model for Search-Oriented Conversational Systems

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    Search-oriented conversational systems rely on information needs expressed in natural language (NL). We focus here on the understanding of NL expressions for building keyword-based queries. We propose a reinforcement-learning-driven translation model framework able to 1) learn the translation from NL expressions to queries in a supervised way, and, 2) to overcome the lack of large-scale dataset by framing the translation model as a word selection approach and injecting relevance feedback in the learning process. Experiments are carried out on two TREC datasets and outline the effectiveness of our approach.Comment: This is the author's pre-print version of the work. It is posted here for your personal use, not for redistribution. Please cite the definitive version which will be published in Proceedings of the 2018 EMNLP Workshop SCAI: The 2nd International Workshop on Search-Oriented Conversational AI - ISBN: 978-1-948087-75-
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