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See detailAn empirical analysis of income convergence in the European Union
Cavenaile, Laurent ULg; Dubois, David ULg

in Applied Economics Letters (2011), 18(17), 1705-1708

In this article, we investigate the convergence process within the European Union. More particularly, we study the convergence process of the new entrants from Central and Eastern Europe and of the 15 ... [more ▼]

In this article, we investigate the convergence process within the European Union. More particularly, we study the convergence process of the new entrants from Central and Eastern Europe and of the 15 Western countries between 1990 and 2007. Applying a panel approach to the convergence equation derived from the Solow model, we show that new entrants and former members of the European Union can be seen as belonging to different groups of convergence. The existence of heterogeneity in the European Union or the Eurozone might affect their stability as the recent Greece’s sovereign debt crisis illustrates it. [less ▲]

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See detailAn Empirical Analysis of Income convergence in the European Union
Cavenaile, Laurent ULg; Dubois, David ULg

E-print/Working paper (2010)

In this paper, we investigate the convergence process within the European Union (27 countries). More particularly, we study the convergence process of the new entrants from Central and Eastern Europe and ... [more ▼]

In this paper, we investigate the convergence process within the European Union (27 countries). More particularly, we study the convergence process of the new entrants from Central and Eastern Europe and of the 15 Western countries between 1990 and 2007. Applying a panel approach to the convergence equation derived by Mankiw et al. (1992) from the Solow model, we highlight the existence of heterogeneity in the European Union and show that new entrants and former members of the European Union can be seen as belonging to significantly differ- ent groups of convergence. The existence of heterogeneity in the European Union or the Eurozone might affect their stability as the recent Greece’s sovereign debt crisis illustrates it. [less ▲]

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See detailAn Empirical Analysis of School Bus Lines Procurement in Wallonia
Gautier, Axel ULg; Thiry, Benjamin

Scientific conference (2013, June)

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See detailAn empirical analysis of trade flows in the food subsector
Tharakan, Joseph ULg

Conference (1997, September)

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See detailAn empirical Bayesian solution to the source reconstruction problem in EEG
Phillips, Christophe ULg; Mattout Jeremie; Rugg, Michael D et al

in Neuroimage (2005), 24(4), 997-1011

Distributed linear solutions of the EEG source localisation problem are used routinely. In contrast to discrete dipole equivalent models, distributed linear solutions do not assume a fixed number of ... [more ▼]

Distributed linear solutions of the EEG source localisation problem are used routinely. In contrast to discrete dipole equivalent models, distributed linear solutions do not assume a fixed number of active sources and rest on a discretised fully 3D representation of the electrical activity of the brain. The ensuing inverse problem is underdetermined and constraints or priors are required to ensure the uniqueness of the solution. In a Bayesian framework, the conditional expectation of the source distribution, given the data, is attained by carefully balancing the minimisation of the residuals induced by noise and the improbability of the estimates as determined by their priors. This balance is specified by hyperparameters that control the relative importance of fitting and conforming to various constraints. Here we formulate the conventional "Weighted Minimum Norm" (WMN) solution in terms of hierarchical linear models. An "Expectation-Maximisation" (EM) algorithm is used to obtain a "Restricted Maximum Likelihood" (ReML) estimate of the hyperparameters, before estimating the "Maximum a Posteriori" solution itself. This procedure can be considered a generalisation of previous work that encompasses multiple constraints. Our approach was compared with the "classic" WMN and Maximum Smoothness solutions, using a simplified 2D source model with synthetic noisy data. The ReML solution was assessed with four types of source location priors: no priors, accurate priors, inaccurate priors, and both accurate and inaccurate priors. The ReML approach proved useful as: (1) The regularisation (or influence of the a priori source covariance) increased as the noise level increased. (2) The localisation error (LE) was negligible when accurate location priors were used. (3) When accurate and inaccurate location priors were used simultaneously, the solution was not influenced by the inaccurate priors. The ReML solution was then applied to real somatosensory-evoked responses to illustrate the application in an empirical setting. (C) 2004 Elsevier Inc. All rights reserved. [less ▲]

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See detailEmpirical comparison of error rate estimators in discriminant analysis
Glele Kakaï, R.; Palm, Rodolphe ULg

Poster (2002, July)

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See detailEmpirical Comparison Of Error Rate-Estimators In Logistic Discriminant Analysis
Glele Kakai, R; Palm, Rodolphe ULg

in Journal of Statistical Computation and Simulation (2009), 79(2),

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See detailAn empirical comparison of machine learning algorithms for generic image classification
Marée, Raphaël ULg; Geurts, Pierre ULg; Visimberga, Giorgio et al

in Proceedings of the 23rd SGAI international conference on innovative techniques and applications of artificial intelligence, Research and development in intelligent systems XX, (2003)

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See detailAn empirical diffusion model for acoustic prediction in rooms with mixted specular and diffuse refections
Foy, Cédric; Valeau, Vincent; Billon, Alexis ULg et al

in Acta Acustica United with Acustica (2009), 95(1), 97-105

In this paper, a modification to the room-acoustic diffusion model is proposed to take different amounts of wall scattering into account. An extensive set of numerical simulations using a cone-tracing ... [more ▼]

In this paper, a modification to the room-acoustic diffusion model is proposed to take different amounts of wall scattering into account. An extensive set of numerical simulations using a cone-tracing software has first been carried out, in order to highlight the impact of the scattering coefficient on the diffusion process in rooms, in terms of sound pressure levels. An iterative method is then proposed to identify, for a given value of the wall’s scattering coefficient, the diffusion constant that allows the stationary sound field to be governed by a diffusion process, regardless of the room’s geometry. Using this method, an empirical law can be proposed between the diffusion constant and the scattering coefficient. The empirical diffusion model is then compared to scale model experiments, as well as to other models from the literature, with a satisfactory agreement for the sound pressure level. However, the empirical diffusion model fails to predict the sound decay for rooms with perfectly specularly reflecting surfaces, due to the inherent concept of a diffusion process. [less ▲]

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See detailAn empirical formula for L line X-ray production cross-section of elements from Ag to U for protons below 3.5 MeV
Strivay, David ULg; Weber, Georges ULg

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2002), 190

When computing element concentration from proton induced X-ray emission analysis, an important parameter is the X-ray production cross-section. There have been numerous experimental and theoretical works ... [more ▼]

When computing element concentration from proton induced X-ray emission analysis, an important parameter is the X-ray production cross-section. There have been numerous experimental and theoretical works in this field. Nonetheless, although there is a simple analytical formula to compute K X-ray cross-sections, there is no such ones for the L lines. We present here analytical formulas for the cross-section of the three main X-ray lines L-alpha L-beta and L-gamma based on experimental data. So far, nearly 3000 values of cross-sections for elements from Ag to U and proton energy ranging from 0.5 to 3.5 MeV have been collected from various references. This experimental data set has been fitted for each Xray line with an exponential function depending on the proton energy and on the element atomic number. These fitted values have then been compared to the experimental data and with theoretical values obtained by the ECPSSR theory and Coster-Kronig fluorescence yields. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailAn empirical formula to estimate the resistance of a convoy in a restricted waterway
Marchal, Jean ULg; Shen, Yide ULg

in Marine Technology and SNAME News (1996), volume 40(2), 107-112

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See detailAn empirical formula to estimate the resistance of a convoy in a restricted waterway
Marchal, Jean ULg; Shen, Yide ULg; Kicheva

in Proceedings of the international conference CAB’95 (Computer Application on Board of Ships), (1995, September)

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See detailEmpirical Influence Functions for Robust Principal Components
Croux, Christophe ULg; Haesbroeck, Gentiane ULg

in 1999 Proceedings of the Statistical Computing Section of the American Statistical Association (1999)

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See detailAn empirical line-by-line model for the infrared solar transmittance spectrum from 700 to 5000 cm(-1)
Hase, F.; Demoulin, Philippe ULg; Sauval, A. J. et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (2006), 102(3), 450-463

An empirical line-by-line model for the infrared solar transmittance spectrum is presented. The model can be incorporated into radiative transfer codes to allow fast calculation of all relevant emission ... [more ▼]

An empirical line-by-line model for the infrared solar transmittance spectrum is presented. The model can be incorporated into radiative transfer codes to allow fast calculation of all relevant emission and absorption features in the solar spectrum in the mid-infrared region from 700 to 5000 cm(-1). The transmittance is modelled as a function of the diameter of the field-of-view centered on the solar disk: the line broadening due to solar rotation as well as center-to-limb variations in strength and width are taken into account for stronger lines. Applications of the model presented here are in the fields of terrestrial remote sensing in the mid-infrared spectral region when the sun is used as radiation source or scattered solar radiation contributes to the measured signal and in the fields of atmospheric radiative transfer algorithms which compute the propagation of infrared solar radiation in the terrestrial atmosphere. (c) 2006 Elsevier Ltd. All rights reserved. [less ▲]

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See detailThe empirical mass distribution of hot B subdwarfs: implications for stellar evolution theory
Van Grootel, Valérie ULg; Fontaine, Gilles; Charpinet, Stéphane et al

in EPJ Web of Conferences (2013, March), 43

Subdwarf B (sdB) stars are hot, compact, and evolved objects that form the very hot end of the horizontal branch, the so-called Extreme Horizontal Branch (EHB). Understanding the formation of sdB stars is ... [more ▼]

Subdwarf B (sdB) stars are hot, compact, and evolved objects that form the very hot end of the horizontal branch, the so-called Extreme Horizontal Branch (EHB). Understanding the formation of sdB stars is one of the remaining challenges of stellar evo- lution theory. Several scenarios have been proposed to account for the existence of such objects, made of He-burning core surrounded by very thin H-rich envelope. They give quite different theoretical mass distributions for the resulting sdB stars. Detailed astero- seismic analyses, including mass estimates, of 15 pulsating hot B subdwarfs have been published since a decade. The masses have also been reliably determined by light curve modeling and spectroscopy for 7 sdB components of eclipsing and/or reflection effect binaries. These empirical mass distributions, although based on small-number statistics, can be compared with the expectations of stellar evolution theory. In particular, the two He white dwarfs merger scenario does not seem to be the dominant channel to form iso- lated sdB stars, while the post-red giant branch scenario is reinforced. This opens new questions on extreme mass loss of red giants to form EHB stars, possibly in connection with the recently discovered close substellar companions and planets orbiting sdB stars. [less ▲]

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See detailThe empirical mass distributions of hot B subdwarfs derived by asteroseismology
Van Grootel, Valérie ULg; Fontaine, Gilles; Brassard, Pierre et al

Conference (2011, October)

Detailed asteroseismic analyses of 15 pulsating B subdwarfs have been published since a decade, including estimates of the masses of these stars. We present in this talk the empirical mass distribution ... [more ▼]

Detailed asteroseismic analyses of 15 pulsating B subdwarfs have been published since a decade, including estimates of the masses of these stars. We present in this talk the empirical mass distribution for hot B subdwarfs on the basis of this sample. We find a sharp mass distribution with a mean mass of 0.470 Msun, a median value of 0.471 Msun, and 68.3% of the stars fall in the narrow range of mass 0.441-0.499 Msun. In a second experiment, we augment our sample with the addition of 5 hot B subdwarfs components of eclipsing binaries, with masses reliably determined by light curve modeling and spectroscopy. The new mass distribution is very similar to the former one with a mean mass of 0.469 Msun, a median value of 0.471 Msun, and a range 0.436-0.501 Msun containing 68.3% of the stars. We also discuss in this talk how these empirical mass distributions, although still based on small-number statistics, compare with the expectations of stellar evolution theory. [less ▲]

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See detailEmpirical Mode Decomposition in the Reduced-Order Modeling of Aeroelastic Systems
Lee, Young S; McFarland, D. Michael; Vakakis, Alexander F. et al

in 49th AIAA Structural Dynamics and Materials Conference, Shaumberg, 2008 (2008)

A relationship between IntrinsicMode Functions (IMFs), derived from the Empirical Mode Decomposition (EMD), and the slow-flow model of a nonlinear dynamical system has been exploited in the development of ... [more ▼]

A relationship between IntrinsicMode Functions (IMFs), derived from the Empirical Mode Decomposition (EMD), and the slow-flow model of a nonlinear dynamical system has been exploited in the development of the Slow Flow Model Identification (SFMI) method for strongly nonlinear systems, in which the physical parameters of such systems are identified from experimental data. Both the slow flows and IMFs provide the means to expand a general multicomponent signal in terms of a series of simpler, dominant, monocomponent signals. The slow flows are obtained analytically, for example through application of the method of complexification and averaging (CxA), which transforms the equations of motion into a set of approximate equations in amplitude and phase for each modeled frequency component. In contrast, the EMD characterizes a signal through the envelope and phase of its elemental components, the IMFs. Thus, between nonlinear transitions, the equations derived using the CxA method govern the amplitude and phase of the modeled IMFs. Application of SFMI has, until now, been limited to low-dimensional systems subjected to impulsive excitation. Herein, the method is extended to identification of a planar rigid airfoil [less ▲]

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See detailEmpirical modelling of the bifurcation behaviour of a bridge deck undergoing across-wind galloping
Andrianne, Thomas ULg; Dimitriadis, Grigorios ULg

in Journal of Wind Engineering & Industrial Aerodynamics (in press)

This work presents an empirical model capable to describe the galloping bifurcation behaviour of a bridge deck. It is based on a general polynomial form proposed by Novak, which we limit to the 5th order ... [more ▼]

This work presents an empirical model capable to describe the galloping bifurcation behaviour of a bridge deck. It is based on a general polynomial form proposed by Novak, which we limit to the 5th order. The advantage of choosing this function for modelling the vertical force coefficient is that asymmetry of the even terms is enforced in order to reproduce the sub-critical aeroelastic behaviour of the bridge deck. The coefficients of the polynomial are identified from several pairs of displacement amplitudes and the corresponding airspeeds, measured in a wind tunnel during dynamic tests on the sectional bridge model. The identification is carried out using a first order harmonic balance technique. A stability analysis is presented in order to highlight the need of such a model to catch the complete bifurcation behaviour of the system. The resulting force coefficient of this full order model is compared to the well known models of Parkinson and Novak. Finally, the concept universal curve is used in order to discuss the galloping responses of square and rectangular cylinders, in comparison with the one of the bridge deck. [less ▲]

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