International Professional University of Technology in Nagoya Repository
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Interpreting Reputation Through Frequent Named Entities in Twitter
No full textInternational audienceTwitter is a social network that provides a powerful source of data. The analysis of those data offers many challenges among those stands out the opportunity to find the reputation of a product, of a person , or of any other entity of interest. Several tools for sentiment analysis have been built in order to calculate the general opinion of an entity using a static analysis of the sentiments expressed in tweets. However, entities are not static; they collaborate with other entities and get involved in events. A simple aggregation of sentiments is then not sufficient to represent this dynamism. In this paper, we present a new approach that identifies the reputation of an entity on the basis of the set of events it is involved into by providing a transparent and self explanatory way for interpreting reputation. In order to perform this analysis we define a new sampling method based on a tweet weighting to retrieve relevant information. In our experiments we show that the 90% of the reputation of the entity originates from the events it is involved into, especially in the case of entities that represent public figures
A universal adaptive controller for tracking and stabilization control of nonholonomic vehicles
No full textWe propose a general class of adaptive controllers for leader-follower simultaneous tracking and stabilization of force-controlled nonholonomic mobile robots, under the hypothesis that the leader velocities are either integrable (parking problem), or persistently exciting (tracking problem). For the first time in the literature, we establish uniform global asymptotic stability for the origin of the closed-loop system (in the kinemtacis state space). We also show that the kinematics controller renders the system robust to perturbations in the sense of integral-to state stability. Then, we show that for the case in which the force dynamics equations are also considered (full model), any velocity-tracking controller with the property that the error velocities are square integrable may be used to ensure global tracking or stabilization. This modularity and robustness of our controller, added to the strength of our stability statements, renders direct the extension of our main results to the difficult scenario of control under para-metric uncertainty
The Universal Fragment of Presburger Arithmetic with Unary Uninterpreted Predicates is Undecidable
No full textThe first-order theory of addition over the natural numbers, known as Presburger arithmetic , is decidable in double exponential time. Adding an uninterpreted unary predicate to the language leads to an undecidable theory. We sharpen the known boundary between decidable and undecidable in that we show that the purely universal fragment of the extended theory is already undecidable. Our proof is based on a reduction of the halting problem for two-counter machines to unsatisfiability of sentences in the extended language of Presburger arithmetic that does not use existential quantification. On the other hand, we argue that a single ∀∃ quantifier alternation turns the set of satisfiable sentences of the extended language into a Σ(1,1)-complete set. Some of the mentioned results can be transfered to the realm of linear arithmetic over the ordered real numbers. This concerns the undecidability of the purely universal fragment and the Σ(1,1)-hardness for sentences with at least one quantifier alternation. Finally, we discuss the relevance of our results to verification. In particular, we derive undecidability results for quantified fragments of separation logic, the theory of arrays, and combinations of the theory of equality over uninterpreted functions with restricted forms of integer arithmetic. In certain cases our results even imply the absence of sound and complete deductive calculi
Power flux brought by an electric arc on AgSnO2 electrodes
No full textInternational audienceIn this paper a method is described which allows estimating the power flux brought by an electric arc on the electrodes. This information is highly important for the understanding of contact erosion mechanisms, as well as for the practical choice of appropriate materials and sizes in switching devices applications. Our method is applied to the case of Ag-SnO 2 electrodes. Compatibility conditions between experimental values of mass loss in well-defined situations and numerical calculations of melted/vaporized metal lead to a maximum surface power density of 8×10 9 W/m 2 for cathode and 2×10 9 W/m 2 for anode. Moreover it is found that less than 16% of the total power brought to the electrodes contributes to metal phase changes
Exploiting non-radiating currents in reflectarray antenna design
No full textInternational audienceA new paradigm for the design of reflectarrays is introduced. The proposed methodology allows the designer to specify constraints/simplifications on the antenna surface current distribution thanks to an innovative exploitation the non-radiating (NR) component, which is regarded a powerful additional degree-of-freedom (DoF) in the synthesis process. An illustrative example is presented, aimed at nulling the current density within a selected sub-region of a planar reflectarray by means of a suitable particle swarm optimization (PSO) of the NR contribution. The effectiveness and the potentialities of the proposed feasible source synthesis methodology are verified by means of a numerical benchmark, opening the doors to a completely new horizon in the design of next generation reflectarrays
Dynamic Pricing for Local Energy Management : Towards a Better Integration of Local Production
No full textInternational audienceDynamic Pricing or TOU ( Time Of Use ) pricing enables grid managers to perform non invasive energy management where consumers keep full control of their energy consumption. The main contribution of this work is to propose a distributed optimization structure to have a better integration of local production. More precisely, instead of having a centralized solution, whose optimization is hard to solve and does not preserve the privacy of the consumers, a distributed solution is proposed, using price inducements. This price is deduced iteratively from an adaptation of augmented Lagrangian technique. The performances of the proposed strategy is compared with the centralized control and a "do nothing" approach
Implications in the Interpretation of Plane-Wave Expansions in Lossy Media and the Need for a Generalized Definition
No full textInternational audiencePlane-wave expansions (PWEs) based on Fourier transform and their physical interpretation are discussed for the case of homogeneous and isotropic lossy media. Albeit being mathematically correct, standard Fourier-based definition leads to nonphysical properties, such as the absence of homogeneous plane waves, lack of dissipation along transversal directions and inaccurate identification of single plane waves. Generalizing the PWE definition using Laplace transform, which amounts to switching to complex spectral variables, is shown to solve these issues, reinstating physical consistency. This approach no longer leads to a unique PWE for a field distribution, as it allows an infinite number of equivalent definitions, implying that the interpretation of the individual components of a PWE as physical plane waves does not appear as justified. The multiplicity of the generalized definitions is illustrated by applying it to the near-field radiation of an elementary electric dipole, for different choices of Laplace cuts, showing the main differences in the generalized PWEs
Temporal Reprogramming of Boolean Networks
No full textInternational audienceCellular reprogramming, a technique that opens huge opportunities in modern and regenerative medicine, heavily relies on identifying key genes to perturb. Most of computational methods focus on finding mutations to apply to the initial state in order to control which attractor the cell will reach. However, it has been shown, and is proved in this article, that waiting between the perturbations and using the transient dynamics of the system allow new reprogramming strategies. To identify these temporal perturbations, we consider a qualitative model of regulatory networks, and rely on Petri nets to model their dynamics and the putative perturbations. Our method establishes a complete characterization of temporal perturbations, whether permanent (mutations) or only temporary, to achieve the existential or inevitable reachability of an arbitrary state of the system. We apply a prototype implementation on small models from the literature and show that we are able to derive temporal perturbations to achieve trans-differentiation
Distributed event-triggered control for multi-agent formation stabilization and tracking
No full textThis paper addresses the problem of formation control and tracking a of desired trajectory by an Euler-Lagrange multi-agentsystems. It is inspired by recent results by Qingkai et al. and adopts an event-triggered control strategy to reduce the numberof communications between agents. For that purpose, to evaluate its control input, each agent maintains estimators of thestates of the other agents. Communication is triggered when the discrepancy between the actual state of an agent and thecorresponding estimate reaches some threshold. The impact of additive state perturbations on the formation control is studied.A condition for the convergence of the multi-agent system to a stable formation is studied. Simulations show the eectivenessof the proposed approach
Logic and Commonsense Reasoning: Lecture Notes
No full textMasterThese are the lecture notes of a course on logic and commonsense reasoning given to master students in philosophy of the University of Rennes 1. N.B.: Some parts of these lectures notes are sometimes largely based on or copied verbatim from publications of other authors. When this is the case, these parts are mentioned at the end of each chapter in the section “Further reading”