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See detailAn iterative approach for the solution of multiple-scattering problems at high-frequencies using finite elements
Geuzaine, Christophe ULg

in Proceedings of the conference The Mathematics of Finite Elements and Applications (MAFELAP 2009) (2009)

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See detailIterative ecological radiation and convergence during the evolutionary history of damselfishes (Pomacentridae)
Frederich, Bruno ULg; Sorenson, Laurie; Santini, Francesco et al

in American naturalist (2013), 181(1), 94-113

Coral reef fishes represent one of the most spectacularly diverse assemblages of vertebrates on the planet, but our understand- ing of their mode of diversification remains limited. Here we test whether ... [more ▼]

Coral reef fishes represent one of the most spectacularly diverse assemblages of vertebrates on the planet, but our understand- ing of their mode of diversification remains limited. Here we test whether the diversity of the damselfishes (Pomacentridae), one of the most species-rich families of reef-associated fishes, was produced by a single or multiple adaptive radiation(s) during their evolutionary history. Tests of the tempo of lineage diversification using a time-calibrated phylogeny including 208 species revealed that crown pomacentrid diversification has not slowed through time as expected under a scenario of a single adaptive radiation resulting from an early burst of diversification. Evolutionary modeling of trophic traits similarly rejected the hypothesis of early among-lineage partitioning of ecologically important phenotypic diversity. Instead, damselfishes are shown to have experienced iterative convergent radiations wherein subclades radiate across similar trophic strategies (i.e., pelagic feeders, benthic feeders, intermediate) and morphologies. Regionalization of coral reefs, competition, and functional constraints may have fueled iterative ecological radiation and convergent evolution of damselfishes. Through the Pomacentridae, we illustrate that radiations may be strongly structured by the nature of the constraints on diversification. [less ▲]

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See detailAn Iterative Finite Element Perturbation Method for Computing Electrostatic Field Distortions
Boutaayamou, Mohamed ULg; V Sabariego, Ruth ULg; Dular, Patrick ULg

in Proceedings of 16th Conference on the Computation of Electromagnetic Fields (COMPUMAG2007) (2007, June)

A finite element (FE) perturbation method for computing electrostatic field distortions due to moving conductors is presented. First, an unperturbed problem (in the absence of conductors) is solved with ... [more ▼]

A finite element (FE) perturbation method for computing electrostatic field distortions due to moving conductors is presented. First, an unperturbed problem (in the absence of conductors) is solved with the conventional FE method in the complete domain. Then, a perturbed problem is computed in a reduced region using the solution of the unperturbed problem as a source field. When the source is close to the perturbing regions, an iterative computation may be required. The developed procedure allows for solving sub-problems in reduced domains with independent problem-adapted meshes. [less ▲]

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See detailAn iterative finite element perturbation method for computing electrostatic field distortions
Boutaayamou, Mohamed ULg; V Sabariego, Ruth ULg; Dular, Patrick ULg

in IEEE Transactions on Magnetics (2008), 44(6), 746-749

A finite element perturbation method is developed for computing electrostatic field distortions and the ensuing charges and forces on moving conductive regions subjected to fixed potentials. It is based ... [more ▼]

A finite element perturbation method is developed for computing electrostatic field distortions and the ensuing charges and forces on moving conductive regions subjected to fixed potentials. It is based on the subsequent solution of an unperturbed problem in a complete domain, where conductive regions have been extracted, and of perturbation problems in subdomains restricted to the surroundings of the added conductive regions. The solution of the unperturbed problem serves as source (with a very reduced support) for the perturbation subproblems. For every new position of the conductors, the solution of the unperturbed problem does not vary and is thus reused; only the perturbation subproblems have to be solved. Further, this approach allows for the use of independent and well-adapted meshes. An iterative procedure is required if the conductive regions are close to the sources. [less ▲]

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See detailIterative finite element solution of multiple-scattering problems at high frequencies
Geuzaine, Christophe ULg; Dular, Patrick ULg; Gaignaire, R. et al

in Proceedings of the 8th International Symposium on Electric and Magnetic Fields (EMF'2009) (2009)

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See detailAn iterative maximum a posteriori estimation of proficiency level to detect multiple local likelihood maxima
Magis, David ULg; Raîche, Gilles

in Applied Psychological Measurement (2010), 34

In this article the authors focus on the issue of the nonuniqueness of the maximum likelihood (ML) estimator of proficiency level in item response theory (with special attention to logistic models). The ... [more ▼]

In this article the authors focus on the issue of the nonuniqueness of the maximum likelihood (ML) estimator of proficiency level in item response theory (with special attention to logistic models). The usual maximum a posteriori (MAP) method offers a good alternative within that framework; however, this article highlights some drawbacks of its use. The authors then propose an iteratively based MAP estimator (IMAP), which can be useful in detecting multiple local likelihood maxima. The efficiency of the IMAP estimator is studied and is compared to the ML and MAP methods by means of a simulation study. [less ▲]

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See detailIterative multi-task sequence labeling for predicting structural properties of proteins
Maes, Francis ULg; Becker, Julien ULg; Wehenkel, Louis ULg

in ESANN 2011 (2011)

Developing computational tools for predicting protein structural information given their amino acid sequence is of primary importance in protein science. Problems, such as the prediction of secondary ... [more ▼]

Developing computational tools for predicting protein structural information given their amino acid sequence is of primary importance in protein science. Problems, such as the prediction of secondary structures, of solvent accessibility, or of disordered regions, can be expressed as sequence labeling problems and could be solved independently by existing machine learning based sequence labeling approaches. But, since these problems are closely related, we propose to rather approach them jointly in a multi-task approach. To this end, we introduce a new generic framework for iterative multi-task sequence labeling. We apply this - conceptually simple but quite effective - strategy to jointly solve a set of five protein annotation tasks. Our empirical results with two protein datasets show that the proposed strategy significantly outperforms the single-task approaches. [less ▲]

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See detailIterative pruning PCA improves resolution of highly structured populations.
Intarapanich, Apichart; Shaw, Philip J.; Assawamakin, Anunchai et al

in BMC bioinformatics (2009), 10

BACKGROUND: Non-random patterns of genetic variation exist among individuals in a population owing to a variety of evolutionary factors. Therefore, populations are structured into genetically distinct ... [more ▼]

BACKGROUND: Non-random patterns of genetic variation exist among individuals in a population owing to a variety of evolutionary factors. Therefore, populations are structured into genetically distinct subpopulations. As genotypic datasets become ever larger, it is increasingly difficult to correctly estimate the number of subpopulations and assign individuals to them. The computationally efficient non-parametric, chiefly Principal Components Analysis (PCA)-based methods are thus becoming increasingly relied upon for population structure analysis. Current PCA-based methods can accurately detect structure; however, the accuracy in resolving subpopulations and assigning individuals to them is wanting. When subpopulations are closely related to one another, they overlap in PCA space and appear as a conglomerate. This problem is exacerbated when some subpopulations in the dataset are genetically far removed from others. We propose a novel PCA-based framework which addresses this shortcoming. RESULTS: A novel population structure analysis algorithm called iterative pruning PCA (ipPCA) was developed which assigns individuals to subpopulations and infers the total number of subpopulations present. Genotypic data from simulated and real population datasets with different degrees of structure were analyzed. For datasets with simple structures, the subpopulation assignments of individuals made by ipPCA were largely consistent with the STRUCTURE, BAPS and AWclust algorithms. On the other hand, highly structured populations containing many closely related subpopulations could be accurately resolved only by ipPCA, and not by other methods. CONCLUSION: The algorithm is computationally efficient and not constrained by the dataset complexity. This systematic subpopulation assignment approach removes the need for prior population labels, which could be advantageous when cryptic stratification is encountered in datasets containing individuals otherwise assumed to belong to a homogenous population. [less ▲]

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See detailIterative solution of high-frequency multiple-scattering problems using finite elements
Geuzaine, Christophe ULg; Vion, Alexandre ULg; V Sabariego, Ruth ULg

in Proceedings of the IVth European Conference on Computational Mechanics (ECCM 2010) (2010)

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See detailIterative solvers and stabilisation for mixed electrostatic and magnetostatic formulations
Deliège, Geoffrey ULg; Rosseel, Eveline; Vandewalle, Stefan

in Journal of Computational & Applied Mathematics (2008), 215(2), 348-356

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See detailIterative Solvers for Large Pressure Dependent Problems
Boman, Romain ULg; Colantonio, Laurent; Ponthot, Jean-Philippe ULg

in Huétink, J.; Baaijens, F. P. T. (Eds.) Proceedings of the Sixth International Conference on Numerical Methods in Industrial Forming Processes (1998, June)

In this paper, we present a stress update scheme for non-deviatoric elastoviscoplastic models, which can be considered as an extension of the radial return method for classical plasticity. We use the ... [more ▼]

In this paper, we present a stress update scheme for non-deviatoric elastoviscoplastic models, which can be considered as an extension of the radial return method for classical plasticity. We use the unconditionally stable backward Euler scheme to obtain the viscoplastic solution at each increment. To solve the large sparse non symmetric iteration matrix, we use the GMRES method. This fast iterative solver, in conjunction with an appropriate preconditioner, can save a lot a memory and CPU time when 3D problem are considered. A comparison between direct and iterative solvers will be discussed on two applications of cold compaction of powders. [less ▲]

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See detailIteratively extending time horizon reinforcement learning
Ernst, Damien ULg; Geurts, Pierre ULg; Wehenkel, Louis ULg

in Machine Learning: ECML 2003, 14th European Conference on Machine Learning (2003)

Reinforcement learning aims to determine an (infinite time horizon) optimal control policy from interaction with a system. It can be solved by approximating the so-called Q-function from a sample of four ... [more ▼]

Reinforcement learning aims to determine an (infinite time horizon) optimal control policy from interaction with a system. It can be solved by approximating the so-called Q-function from a sample of four-tuples (x(t), u(t), r(t), x(t+1)) where x(t) denotes the system state at time t, ut the control action taken, rt the instantaneous reward obtained and x(t+1) the successor state of the system, and by determining the optimal control from the Q-function. Classical reinforcement learning algorithms use an ad hoc version of stochastic approximation which iterates over the Q-function approximations on a four-tuple by four-tuple basis. In this paper, we reformulate this problem as a sequence of batch mode supervised learning problems which in the limit converges to (an approximation of) the Q-function. Each step of this algorithm uses the full sample of four-tuples gathered from interaction with the system and extends by one step the horizon of the optimality criterion. An advantage of this approach is to allow the use of standard batch mode supervised learning algorithms, instead of the incremental versions used up to now. In addition to a theoretical justification the paper provides empirical tests in the context of the "Car on the Hill" control problem based on the use of ensembles of regression trees. The resulting algorithm is in principle able to handle efficiently large scale reinforcement learning problems. [less ▲]

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See detailItinéraire d’une fable : le Loup et le Chien
Pietquin, Paul ULg; Dachy, Françoise; Debrux, Thomas et al

in Etudes Classiques (Namur, Belgium) (1994), 62

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See detailL'itinéraire de Candide Wizo : un élément de datation des oeuvres anti-adoptianistes d'Alcuin? Note sur les lettres 41 et 204 de la correspondance d'Alcuin
Close, Florence ULg

in Revue d'Histoire Ecclésiastique (2008), 103(1), 5-26

In E. Dummler’s edition of Alcuin’s correspondence, L. 41 bears the date 794-795. This chronological indication has never been refuted. However, the topics dealt with in this document obviously refer to ... [more ▼]

In E. Dummler’s edition of Alcuin’s correspondence, L. 41 bears the date 794-795. This chronological indication has never been refuted. However, the topics dealt with in this document obviously refer to the second adoptianist problem (797-799), during which Candidus Wido acted as an intermediary between the Frankish court and the abbey of St. Martin de Tours. A critical reading, carefully taking into account the itinerary of Alcuin’s disciple, leads one to assign the writing of L.41 to the autumn of 798. It is, moreover, advisable to amend the critical commentary consecrated to L. 204 in the Clavis des auteurs latins du moyen age. Clavis Wizo did not present the Contra Felicem libri V11 to the court. [less ▲]

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See detailUn itinéraire du Sart Tilman
Frankignoulle, Pierre ULg; Merch, Marie-Christine ULg

E-print/Working paper (2010)

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See detailItinéraire géologique et paleontologique dans la carrière d'Ampsin (Amay, Belgique)
Barchy, Laurent; Marion, Jean-Marc ULg; Poty, Edouard ULg

Diverse speeche and writing (2008)

Close to the museum "Master of the Fire" at Ampsin (Amay, Belgium), an abandoned quarry is used to present both the local and regional geologic history, and the fauna and flora related to the site. For ... [more ▼]

Close to the museum "Master of the Fire" at Ampsin (Amay, Belgium), an abandoned quarry is used to present both the local and regional geologic history, and the fauna and flora related to the site. For all. [less ▲]

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See detailLes itinéraires cliniques
ERPICUM, Marie ULg

Scientific conference (2014, May 09)

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See detailItinéraires sylvicoles pour la production de frêne de qualité
Claessens, Hugues ULg

Book published by Faculté universitaire des sciences agronomiques de Gembloux (1997)

This paper presents ash in Wallonia (Southern Belgium) and defines its silviculture in the respect of its characteristics (light demanding species, fast juvenile growth, site fertility demanding) and its ... [more ▼]

This paper presents ash in Wallonia (Southern Belgium) and defines its silviculture in the respect of its characteristics (light demanding species, fast juvenile growth, site fertility demanding) and its wood market ( joinery wood, slicing). Two silvicultural ways are presented : “intensive silviculture” and “near-to-nature silviculture”, that are both based upon very similar guidelines (heavy and early thinnings in relation to objective-trees, short rotation, early harvesting) but differ by planting spacings and technical ways used to obtain a high quality butt log. At last, the influence of the proposed ash silviculture is evaluated from a biodiversity point of view, and some ways to preserve the floristic diversity dynamic are suggested. [less ▲]

Detailed reference viewed: 52 (4 ULg)