756 research outputs found

    A Bank of Reconfigurable LQG Controllers for Linear Systems Subjected to Failures

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    An approach for controller reconfiguration is presented. The starting point in the analysis is a sufficiently accurate continuous linear time-invariant (LTI) model of the nominal system. Based on a bank of reconfigurable LQG controllers, each designed for a particular combination of total faults, the reconfiguration consists of two operation modes. In the first mode a switching is invoked towards one of the pre-designed LQG controllers on the basis of the information about only the combination of total faults that is in effect. In the second mode, which is activated in cases of partial and component faults, a dynamic correction procedure is initiated which tries to reconfigure the currently active controller in such a way, that the failed closed-loop system remains stable and its performance is as close as possible to the performance of the closed-loop system with only total faults present in the system. In cases of partial faults the second mode is practically an extension of the modified pseudo-inverse method. In cases of component faults the second mode is based on an LMI optimization problem. The approach is illustrated using a model of a real-life space robot manipulator, in which total, partial and component faults are simulate

    Nonlinear Compressive Particle Filtering

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    Many systems for which compressive sensing is used today are dynamical. The common approach is to neglect the dynamics and see the problem as a sequence of independent problems. This approach has two disadvantages. Firstly, the temporal dependency in the state could be used to improve the accuracy of the state estimates. Secondly, having an estimate for the state and its support could be used to reduce the computational load of the subsequent step. In the linear Gaussian setting, compressive sensing was recently combined with the Kalman filter to mitigate above disadvantages. In the nonlinear dynamical case, compressive sensing can not be used and, if the state dimension is high, the particle filter would perform poorly. In this paper we combine one of the most novel developments in compressive sensing, nonlinear compressive sensing, with the particle filter. We show that the marriage of the two is essential and that neither the particle filter or nonlinear compressive sensing alone gives a satisfying solution.Comment: Accepted to CDC 201

    Gene flow estimation with microsatellites in a Malagasy seed orchard of Eucalyptus grandis

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    International audienceEucalyptus grandis has a mixed-mating repro- ductive system. Malagasy Eucalyptus seed orchards were established 15 years ago with two aims both based on panmixia: open-pollinated seed production and genetic improvement. The panmixia hypothesis has never been confirmed in the seed orchard. From a seedling seed- orchard stand comprising 349 trees and using data obtained with six selected microsatellite markers, pater- nity analysis was performed for 724 offspring collected on 30 adult trees. Paternity assignment, based on exclu- sion procedures and likelihood-ratio method, was achieved with high accuracy; the exclusion probability value was 0.997. The outcrossing rate was very high (96.7%). More than 50% of potential male trees (199 out of 349) in the seed orchard contributed to pollination for 440 offspring of 30 progenies (8.6% of the basic population). The pollination rate from outside the seed orchard was high (39.2%), but might be due to the small size of this seed orchard. This study showed that "panmixia-like pollination" can be assume

    Inhibition of Trophoblast-Induced Spiral Artery Remodeling Reduces Placental Perfusion in Rat Pregnancy.

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    Rats harboring the human angiotensinogen and human renin genes develop preeclamptic features in pregnancy. The preeclamptic rats exhibit a deeper trophoblast invasion associated with a reduced resistance index by uterine Doppler. Doxycycline inhibits matrix metalloproteinase activity. We tested the hypothesis that matrix metalloproteinase inhibition reduces trophoblast invasion with subsequent changes in placental perfusion. Preeclamptic and pregnant control Sprague-Dawley rats were treated with doxycycline (30 mg/kg of body weight orally) from gestational day 12 until day 18. Placental perfusion was assessed using a micromarker contrast agent. The animals were euthanized on day 18 of pregnancy; biometric data were acquired, and trophoblast invasion was analyzed. Doxycycline resulted in intrauterine growth retardation and lighter placentas in both groups. Maternal body weight was not affected. As shown earlier, preeclamptic rats exhibited a deeper endovascular trophoblast invasion. However, doxycycline treatment reduced trophoblast invasion in the preeclamptic rats. The physiological spiral artery remodeling, as assessed by the deposition of fibrinoid and α-actin in the spiral artery contour, was significantly reduced by doxycycline. The vascularity index, as assessed by perfusion measurement of the placenta, was reduced after doxycycline treatment in preeclamptic rats. Thus, matrix metalloproteinase inhibition with doxycycline leads to reduced trophoblast invasion and associated reduced placental perfusion. These studies are the first to show that reducing trophoblast-induced vascular remodeling decreases subsequent placental perfusion. Our model allows the study of dysregulated trophoblast invasion and vascular remodeling in vivo to gain important insights into preeclampsia-related mechanisms

    The politics of international redistribution: Explaining public support for fiscal transfers in the EU

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    This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.As a consequence of the Eurozone crisis and the creation of the European Stability Mechanism (ESM), the prospect of a transfer union has become a particularly contested aspect of European integration. How should one understand the public backlash against fiscal transfers? And, what explains voter preferences for international transfers more generally? Using data from the 2014 European Elections Study (EES), this article describes the first cross-national analysis of voters’ preferences on international transfers. The analysis reveals a strong association between voters’ non-economic cultural orientations (i.e., their cosmopolitanism) and their position on transfers. At the same time, it is found that voters’ economic left-right orientations are crucial for a fuller understanding of the public conflict over transfers. This counters previous research that finds economic left-right orientations to be of little explanatory value. This study demonstrates that the association between economic left-right orientations and preferences for international transfers is conditional on a person's social class. Among citizens in a high-income class an economically left-leaning position is associated with support for transfers, whereas it is associated with opposition to transfers among citizens in a low-income class

    Nosocomial infective endocarditis: should the definition be extended to 6 months after discharge

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    ABSTRACTBecause the microbiology and patient population of infective endocarditis (IE) have evolved, the traditional definition of nosocomial IE may require revision. The question of whether this definition should be extended to 6 months after discharge was explored, and a high rate of episodes with nosocomial pathogens (coagulase-negative staphylococci) and a low rate of episodes with community pathogens (streptococci) in the extended nosocomial group were found. Therefore, modification of the traditional definition is proposed, distinguishing between early (as traditionally described) and late nosocomial IE (IE in association with a significant invasive procedure performed during a hospitalization between 8 weeks and 6 months before the onset of symptoms)

    The elite–citizen gap in international organization legitimacy

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    Scholars and policy makers debate whether elites and citizens hold different views of the legitimacy of international organizations (IOs). Until now, sparse data has limited our ability to establish such gaps and to formulate theories for explaining them. This article offers the first systematic comparative analysis of elite and citizen perceptions of the legitimacy of IOs. It examines legitimacy beliefs toward six key IOs, drawing on uniquely coordinated survey evidence from Brazil, Germany, the Philippines, Russia, and the United States. We find a notable elite–citizen gap for all six IOs, four of the five countries, and all of six different elite types. Developing an individual-level approach to legitimacy beliefs, we argue that this gap is driven by systematic differences between elites and citizens in characteristics that matter for attitudes toward IOs. Our findings suggest that deep-seated differences between elites and general publics may present major challenges for democratic and effective international cooperation.Riksbankens Jubileumsfond (Grant M15-0048:1)Security and Global AffairsInstitutions, Decisions and Collective Behaviou
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