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See detailOn generalized Hölder spaces
Kreit, Damien ULg

Conference (2011, January 21)

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See detailOn generalized Hölder-Zygmund spaces
Kreit, Damien ULg; Nicolay, Samuel ULg

Poster (2013, October 29)

The Hölder spaces provide a natural way for measuring the smoothness of a function. These spaces appear in different areas such as approximation theory and multifractal analysis. The purpose of this ... [more ▼]

The Hölder spaces provide a natural way for measuring the smoothness of a function. These spaces appear in different areas such as approximation theory and multifractal analysis. The purpose of this poster is to present a generalization of such spaces as well as some recent results about their characterizations. These spaces are a particular case of a generalization of Besov Spaces who have recently been extensively studied. [less ▲]

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See detailOn input-to-output stability of switched non-exponentially stable nonlinear systems
Efimov, Denis ULg; Panteley, Elena; Loria, Antonio

in Proc. European Control Conference, Budapest (2009)

The problem of input-to-output stability for switched nonlinear systems is considered. Two approaches for switching between non-exponentially stable systems are proposed guaranteeing input-to-output ... [more ▼]

The problem of input-to-output stability for switched nonlinear systems is considered. Two approaches for switching between non-exponentially stable systems are proposed guaranteeing input-to-output stability for the switched system. [less ▲]

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See detailOn Interpreting g-Mode Period Spacings in sdB Stars
Charpinet, Stéphane; Brassard, Pierre; Van Grootel, Valérie ULg et al

in Astronomical Society of the Pacific Conference Series (2014), 481

Long period B subdwarf (sdB) pulsators, when observed from space with the satellites CoRoT and Kepler, show particularly rich g-mode oscillation spectra with often hundreds of frequencies. In many of ... [more ▼]

Long period B subdwarf (sdB) pulsators, when observed from space with the satellites CoRoT and Kepler, show particularly rich g-mode oscillation spectra with often hundreds of frequencies. In many of these pulsation spectra, regularities in the observed period distributions typical of high order g-modes in chemically homogeneous stars have been reported. This led to a claim that sdB stars could be much less chemically stratified than previously thought. In this paper, we show that such an interpretation is unfounded. We reinvestigate trapping effects on g-modes in sdB stars in view of current observations and show that ”standard” stratified models can also produce nearly quasi-constant period spacings in the low frequency range which are comparable to those observed in the g-mode spectra of these stars. [less ▲]

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See detailOn Inverse Problems in Turbine Engine Parameter Estimation
Henriksson, Mattias; Borguet, Sébastien ULg; Léonard, Olivier ULg et al

in Proceedings of the ASME Turbo Expo 2007 (2007, May)

This paper extends previous work on model order reduction based on singular value decomposition. It is shown how the decrease in estimator variance must be balanced against the bias on the estimate ... [more ▼]

This paper extends previous work on model order reduction based on singular value decomposition. It is shown how the decrease in estimator variance must be balanced against the bias on the estimate inevitably introduced by solving the inverse problem in a reduced order space. A proof for the decrease in estimator variance by means of multi-point analysis is provided. The proof relies on comparing the Cramer-Rao lower bound of the single point and the multi-point estimators. Model order selection is discussed in the presence of a varying degree of a priori parameter information, through the use of a regularization parameter. Simulation results on the SR-30 turbojet engine indicate that the theoretically attainable multi-point improvements are difficult to realize in practical jet engine applications. [less ▲]

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See detailOn Iterating Linear Transformations over Recognizable Sets of Integers
Boigelot, Bernard ULg

in Theoretical Computer Science (2003), 309(1-3), 413-468

It has been known for a long time that the sets of integer vectors that are recognizable by finite-state automata are those that can be defined in an extension of Presburger arithmetic. In this paper, we ... [more ▼]

It has been known for a long time that the sets of integer vectors that are recognizable by finite-state automata are those that can be defined in an extension of Presburger arithmetic. In this paper, we address the problem of deciding whether the closure of a linear transformation preserves the recognizable nature of sets of integer vectors. We solve this problem by introducing an original extension of the concept of recognizability to sets of vectors with complex components. This generalization allows to obtain a simple necessary and sufficient condition over linear transformations, in terms of the eigenvalues of the transformation matrix. We then show that these eigenvalues do not need to be computed explicitly in order to evaluate the condition, and we give a full decision procedure based on simple integer arithmetic. The proof of this result is constructive, and can be turned into an algorithm for applying the closure of a linear transformation that satisfies the condition to a finite-state representation of a set. Finally, we show that the necessary and sufficient condition that we have obtained can straightforwardly be turned into a sufficient condition for linear transformations with linear guards. [less ▲]

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See detailOn Kinetic Theory Justifications of Extended Irreversible Thermodynamics
Lebon, Georgy ULg; Dauby, Pierre ULg; Grmela, M.

in Shizgal, B. D.; Weaver, D. P. (Eds.) Rarefied Gaz Dynamics : Experimental Techniques and Physical Systems (1994)

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See detailOn knots in epidural catheters: a case report and a review of the literature
Brichant, Jean-François ULg; Bonhomme, Vincent ULg; Hans, Pol ULg

in International Journal of Obstetric Anesthesia (2006), 15(2), 159-162

A lumbar epidural catheter placed for labor analgesia proved to be difficult to remove after an uneventful delivery. With the patient in the position of catheter insertion, i.e. seated, firm and steady ... [more ▼]

A lumbar epidural catheter placed for labor analgesia proved to be difficult to remove after an uneventful delivery. With the patient in the position of catheter insertion, i.e. seated, firm and steady traction allowed removal of the catheter and revealed a knot 4 mm from its tip. Passing excessive amount of catheter into the epidural space may have contributed to this complication. Guidelines to prevent and to minimize this complication are suggested. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

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See detailOn Learning Subtypes of the Part-Whole Relation: Do Not Mix Your Seeds
Ittoo, Ashwin ULg; Bouma, Gosse

in Proceedings of the Association for Computational Linguistics (2010)

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See detailOn les désigne comme "handicapés mentaux" : Naissance et conséquence d'une étiquette
Beckers, Jacqueline ULg

in Sauvegarde de l'Enfance (1988), 1

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See detailOn mathematical concepts for the material world
Leclercq, Bruno ULg

Conference (2008, September 25)

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See detailOn micromechanical damage modeling in geomechanics: influence of numerical integration scheme
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in International Journal of Computational & Applied Mathematics (2013), 246

Tunnel excavations in deep rocks provide stress perturbations which initiate diffuse and/or localized damage propagation in the material. This damage phenomenon can lead to significant irreversible ... [more ▼]

Tunnel excavations in deep rocks provide stress perturbations which initiate diffuse and/or localized damage propagation in the material. This damage phenomenon can lead to significant irreversible deformations and changes in rock properties. In this paper, we propose to model such behavior by considering a micromechanically-based damage approach. The resulting micromechanical model, which also accounts for initial stress, is described and assessed through the numerical analysis of a synthetic tunnel drilling in Opalinus Clay. A particular emphasis is put on the numerical integration of the model. In particular, an appropriate choice of the latter is required to ensure the numerical stability and a confident prediction of excavation damaged zone around tunnels. [less ▲]

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See detailOn modal interactions in strongly nonlinear systems
Peeters, Maxime ULg; Kerschen, Gaëtan ULg; Golinval, Jean-Claude ULg

in Euromech 503, Nonlinear Normal Modes, Dimension Reduction and Localization in Vibrating Systems, Frascati, 2009 (2009)

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See detailOn multi-area control in electric power systems
Zima, Marek; Ernst, Damien ULg

in Proceedings of the 15th Power System Computation Conference (PSCC 2005) (2005)

In this paper we study the concept of electric power system control, when the responsibility for controlling the entire system is shared by agents controlling their assigned areas. Within this framework ... [more ▼]

In this paper we study the concept of electric power system control, when the responsibility for controlling the entire system is shared by agents controlling their assigned areas. Within this framework, we suggest to study the dynamics created by the interactions of agents. In particular, we discuss the relation that exists between the information available to the different agents and their optimisation objective, and the performance of the overall power system. Simulations results, carried out on a 39-node power system voltage control problem, are provided and analyzed. They highlight, among others, the sub-optimal performance level attained by the system when the different agents exchange information about their area dynamics without sharing a common control objective. [less ▲]

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See detailOn multi-area security assessment of large interconnected power systems
Wehenkel, Louis ULg; Glavic, Mevludin; Ernst, Damien ULg

in Proceedings of the Second Carnegie Mellon Conference in Electric Power Systems: Monitoring, Sensing, Software and its Valuation for the Changing electric Power Industry (2006)

The paper introduces a framework for information exchange and coordination of security assessment suitable for distributed multi-area control in large interconnections operated by a team of transmission ... [more ▼]

The paper introduces a framework for information exchange and coordination of security assessment suitable for distributed multi-area control in large interconnections operated by a team of transmission system operators. The basic idea of the proposed framework consists of exchanging just enough information so that each operator can evaluate the impact in his control area of contingencies both internal and external to his area. The framework has been thought out with the European perspective in mind where it is presently not possible to set up a transnational security coordinator that would have authority to handle security control over the whole or part of the European interconnection. Nevertheless, it can also be considered as an approach to handle security control in North-American Mega-RTOs, where it could help to circumvent problems of scalability of algorithms and maintainability of data by distributing them over the TSOs under the authority of the RTO. [less ▲]

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See detailOn natural and conformally invariant quantizations
Mathonet, Pierre ULg; Radoux, Fabian ULg

in Journal of the London Mathematical Society (2009), 80(1), 256-272

The concept of conformally equivariant quantization was introduced by Duval, Lecomte and Ovsienko for manifolds endowed with flat conformal structures. They obtained results of existence and uniqueness ... [more ▼]

The concept of conformally equivariant quantization was introduced by Duval, Lecomte and Ovsienko for manifolds endowed with flat conformal structures. They obtained results of existence and uniqueness (up to normalization) of such a quantization procedure. A natural generalization of this concept is to seek for a quantization procedure, over a manifold M, that depends on a pseudo-Riemannian metric, is natural, and is invariant with respect to a conformal change of the metric. The existence of such a procedure was conjectured by P. Lecomte and proved by C. Duval and V. Ovsienko for symbols of degree at most 2 and by S. Loubon Djounga for symbols of degree 3. In two recent papers, we investigated the question of existence of projectively equivariant quantizations using the framework of Cartan connections. Here we will show how the formalism developed in these works adapts in order to deal with the conformally equivariant quantization for symbols of degree at most 3. This will allow us to easily recover earlier results on the subject. We will then show how it can be modified in order to prove the existence of conformally equivariant quantizations for symbols of degree 4. [less ▲]

Detailed reference viewed: 14 (4 ULg)