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Peer Reviewed
See detailHomogeneous and fractal behavior of superconducting fluctuations in the electrical resistivity of granular ceramic superconductors
Ausloos, Marcel ULg; Clippe, Paulette ULg; Laurent, Christian

in Physical Review B (1990), 41(13), 9506-9509

Experimental data show that the electrical-resistivity temperature derivative diverges in a different manner in the granular ceramic superconductors YBa2Cu3O7-y and Bi1.75Pb0.25Ca2Sr2Cu3O10-y. Critical ... [more ▼]

Experimental data show that the electrical-resistivity temperature derivative diverges in a different manner in the granular ceramic superconductors YBa2Cu3O7-y and Bi1.75Pb0.25Ca2Sr2Cu3O10-y. Critical exponents are extracted and explained. The dimensionality of anomalous superconductivity fluctuations is deduced. A homogeneous case and a self-similar (fractal) behavior can occur and are found. They correspond to different values of the superconductivity s and some percolation p coherence-length ratio. The results indicate that superconductivity percolation is achieved through surface connection rather than through path connection. [less ▲]

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See detailHomogeneous Lyapunov Functions and Necessary Conditions for Stabilization
Sepulchre, Rodolphe ULg; Aeyels, D.

in Journal of mathematics for control, signal and systems (1996), 9(1), 34-58

We provide necessary conditions for the stabilization of nonlinear control systems with the additional requirement that a time-invariant homogeneous Lyapunov function exists for the closed-loop system.

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See detailHomogenisation of Windings and Laminations in Time-Domain Finite-Element Modeling of Electrical Machines
Gyselinck, Johan; Geuzaine, Christophe ULg; Vazquez Sabariego, Ruth ULg

in Proceedings of the 15th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2012) (2012, November)

This paper deals with time-domain homogenisation of multi-turn windings and laminated cores in 2D and 3D finite- element (FE) modelling of rotating electrical machines. Herein the number of additional ... [more ▼]

This paper deals with time-domain homogenisation of multi-turn windings and laminated cores in 2D and 3D finite- element (FE) modelling of rotating electrical machines. Herein the number of additional degrees of freedom (auxiliary field variables) in the homogenised regions can be fixed depending on the extent of the eddy current effects and on the desired accuracy. The homogenisation technique is illustrated and validated by means of a 2D model of a switched reluctance motor. Global quantities, such as the phase impedance, converge very well to those produced by a precise but very expensive 3D model. [less ▲]

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See detailHomogenization of fibre reinforced composite with gradient enhanced damage model
Wu, Ling ULg; Noels, Ludovic ULg; Adam, Laurent et al

in Hogge, Michel; Van Keer, Roger; Dick, Erik (Eds.) et al Proceedings of the 5th International Conference on Advanded COmputational Methods in Engineering (ACOMEN2011) (2011, November)

Classical finite element simulations face the problems of losing uniqueness and strain localization when the strain softening of materials is involved. Thus, when using continuum damage model or ... [more ▼]

Classical finite element simulations face the problems of losing uniqueness and strain localization when the strain softening of materials is involved. Thus, when using continuum damage model or plasticity softening model, numerical convergence will not be obtained with the refinement of the finite element discretization when strain localization occurs. Gradient-enhanced softening and non-local continua models have been proposed by several researchers in order to solve this problem. In such approaches, high-order spatial gradients of state variables are incorporated in the macroscopic constitutive equations. However, when dealing with complex heterogeneous materials, a direct simulation of the macroscopic structures is unreachable, motivating the development of non-local homogenization schemes. In this work, a non-local homogenization procedure is proposed for fiber reinforced materials. In this approach, the fiber is assumed to remain linear elastic while the matrix material is modeled as elasto-plastic coupled with a damage law described by a non-local constitutive model. Toward this end, the mean-field homogenization is based on the knowledge of the macroscopic deformation tensors, internal variables and their gradients, which are applied to a micro- structural representative volume element (RVE). Macro-stress is then obtained from a homogenization process. [less ▲]

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See detailHomogenization of form- wound windings in finite element modelling of electrical machines
Gyselinck, Johan; Dular, Patrick ULg; Sadowski, Nelson et al

in IEEE Transactions on Magnetics (2010), 46(8), 2852-2855

In this paper, the authors deal with the finite-element (FE) modeling of eddy-current effects in form-wound windings of electrical machines using a previously proposed general frequency- and time-domain ... [more ▼]

In this paper, the authors deal with the finite-element (FE) modeling of eddy-current effects in form-wound windings of electrical machines using a previously proposed general frequency- and time-domain homogenization method. By way of demonstration and validation, a real-life 1250-kW induction machine with double-layer stator winding is considered. The skin and proximity effects in one stator conductor (copper bar) are first quantified by means of a simple low-cost FE model, leading to complex and frequency-dependent coefficients for the homogenized winding (reluctivity for proximity effect and conductivity or resistance for skin effect). These complex coefficients are subsequently translated into real-valued and constant coefficients that allow for time-domain homogenization when introducing a limited number of additional degrees of freedom in the FE model. All results obtained with the homogenized model (considering one conductor or a complete slot) agree well with those produced by a brute-force approach (modeling and finely discretizing each conductor). [less ▲]

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See detailHomogenization of lamination stacks in linear magnetodynamics
Krahenbuhl, Laurent; Dular, Patrick ULg; Zeidan, Tarek et al

in IEEE Transactions on Magnetics (2004), 40(2, Part 2), 912-915

An effective numerical modeling of devices with lamination stacks cannot be done without replacing the laminations by an equivalent solid region. So far, no convincing model has been proposed, even in the ... [more ▼]

An effective numerical modeling of devices with lamination stacks cannot be done without replacing the laminations by an equivalent solid region. So far, no convincing model has been proposed, even in the "simple" case of linear magnetodynamics-particularly if the resultant current in each sheet does not cancel. In this paper, we define the homogenized fields, and the related material properties. The noteworthy precision of the theoretic homogenized solution is shown and discussed by comparing it with the exact solution of the problem with laminations in the case of a simple "1.5-D" analytical test problem. The three-dimensional finite element solutions-real description of the sheets, refined mesh/homogenized region, coarser mesh-for the same test problem show also a perfect agreement. [less ▲]

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See detailHomogenization of laminations and windings in low frequency electromagnetism
V Sabariego, Ruth ULg

Scientific conference (2009, September)

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See detailHomogenization techniques in electromagnetics
Vazquez Sabariego, Ruth ULg

Scientific conference (2011, August)

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See detailHomogenization techniques in low frequency electromagnetics
Vazquez Sabariego, Ruth ULg

Scientific conference (2011, January 03)

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See detailHomogenization techniques in low frequency problems
V Sabariego, Ruth ULg

Scientific conference (2008, March)

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See detailHomogenization with propagation of instabilities through the different scales
Noels, Ludovic ULg; Wu, Ling ULg; Nguyen, Van Dung ULg et al

Scientific conference (2014, January 31)

In this work, multi-scale methods with strain softening are developed in the contexts of damage modeling for composite laminates and of buckling analyses in cellular materials. First, an anisotropic ... [more ▼]

In this work, multi-scale methods with strain softening are developed in the contexts of damage modeling for composite laminates and of buckling analyses in cellular materials. First, an anisotropic gradient–enhanced continuum damage model is embedded in a mean–field homogenization (MFH) process for elasto-plastic composites. The homogenization procedure is based on the newly developed incremental secant mean-field homogenization formulation, for which the residual stress and strain states reached in the phases upon a fictitious elastic unloading are considered as starting point to apply the secant method. The mean stress fields in the phases are then computed using isotropic secant tensors, which are naturally used to define the Linear Comparison–Composite The resulting multi– scale model is then applied to study the damage process at the meso–scale of laminates, and in particular the damaging of plies in a composite stack. By using the gradient–enhanced continuum damage model, the problem of losing uniqueness upon strain softening is avoided. Second, an efficient multi–scale finite element framework capturing the buckling instabilities in cellular materials is developed. As a classical multi–scale computational homogenization scheme loses accuracy with the apparition of the macroscopic localizations resulting from the micro–buckling, the second order multi–scale computational homogenization scheme is considered. This second–order computational framework is enhanced with the following novelties so that it can be used for cellular materials. At the microscopic scale, the periodic boundary condition is used because of its efficiency. As the meshes generated from cellular materials exhibit a large void part on the boundaries and are not conforming in general, the classical enforcement based on the matching nodes cannot be applied. A new method based on the polynomial interpolation2 without the requirement of the matching mesh condition on opposite boundaries of the representative volume element (RVE) is developed. Next, in order to solve the underlying macroscopic Mindlin strain gradient continuum of this second–order scheme by the displacement–based finite element framework, the treatment of high order terms is based on the discontinuous Galerkin (DG) method to weakly impose the C1-continuity. Finally, as the instability phenomena are considered at both scales of the cellular materials, the path following technique is adopted to solve both the macroscopic and microscopic problems. [less ▲]

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See detailHomogenizing clinical training through ‘à la carte’ self-directed learning
Maillart, Christelle ULg; Grevesse, Pascale; Wiot, Nathalie

Poster (2012, May 25)

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See detailHomoleptic Diphosphacyclobutadiene Complexes [M(4-P2C2R2)2]x- (M=Fe, Co; x=0, 1),
Wolf, Robert; Ehlers, Andreas W; Khusniyarov, Marat M et al

in Chemistry : A European Journal (2010), 16

The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands is reported. Compounds [K([18]crown-6)(thf)2][Fe(h4- P2C2tBu2)2 ... [more ▼]

The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands is reported. Compounds [K([18]crown-6)(thf)2][Fe(h4- P2C2tBu2)2] (K1), [K([18]crown-6)-(thf)2][Co(h4-P2C2tBu2)2] (K2), and [K([18]crown-6)(thf)2][Co(h4- P2C2Ad2)2] (K3, Ad=adamantyl) were obtained from reactions of [K([18]crown-6)(thf)2][M(h4-C14H10)2] (M=Fe, Co) with tBuC P (1, 2), or with AdC P (3). Neutral sandwiches [M(h4-P2C2tBu2)2] (4: M=Fe 5: M= Co) were obtained by oxidizing 1 and 2 with [Cp2Fe]PF6. Cyclic voltammetry and spectro-electrochemistry indicates that the pairs [M(h4-P2C2tBu2)2] / [M(h4-P2C2tBu2)2] can be reversibly interconverted by one electron oxidation and reduction, respectively. Complexes 1–5 were characterized by multinuclear NMR, EPR (1 and 5), UV/Vis, and Mçssbauer spectroscopies (1 and 4), mass spectrometry (4 and 5), and microanalysis (1–3). The molecular structures of 1–5 were determined by usingX-ray crystallography. Essentially D2dsymmetric structures were found for all five complexes, which show the two 1,3-diphosphacyclobutadiene rings in a staggered orientation. Density functional theory calculations revealed the importance of covalent metal–ligand p bonding in 1–5. Possible oxidation state assignments for the metal atoms are discussed. [less ▲]

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See detailL'homologation judiciaire des conventions. Essai d'une théorie générale.
Moreau, Pierre ULg

Doctoral thesis (2007)

Lorsqu’il recourt à la technique de l’homologation en matière contractuelle, le législateur permet ou impose aux parties qu’aucun litige n’oppose (plus), de soumettre leur convention au contrôle d’un juge ... [more ▼]

Lorsqu’il recourt à la technique de l’homologation en matière contractuelle, le législateur permet ou impose aux parties qu’aucun litige n’oppose (plus), de soumettre leur convention au contrôle d’un juge. Bien que la décision que le juge rend à l’issue de ce contrôle soit susceptible de modifier le rapport contractuel de base, le législateur n’a pas défini le régime et les effets de l’homologation. L’auteur tente de mettre au jour le corps des règles communes aux différentes homologations de contrats et de préciser, eu égard à ces règles, l’incidence de l’intervention judiciaire sur les relations des parties entre elles et vis-à-vis des tiers. Dans la première partie de l’étude, est développé le contexte dans lequel s’inscrit l’homologation judiciaire des conventions. Cette partie est axée sur les deux aspects que comporte ce contexte; le premier titre est consacré au rôle du juge face au litige et le second au rôle du juge face au contrat. La seconde partie de l’étude contient les développements propres à la théorie de l’homologation judiciaire des conventions. Pour construire cette théorie, l’auteur est amené à conjuguer la nature contractuelle de la convention soumise à homologation et la nature judiciaire de cette dernière. En définitive, il s’agit de répondre à la question qui sous-tend le concept : l’homologation transmue-t-elle la convention qui lui est soumise ? Par l’élaboration de la théorie générale, l’auteur a cherché à faciliter la tâche des magistrats appelés, dans nombre d’hypothèses, à homologuer des conventions, comme à éclairer les praticiens, sur les effets de l’homologation judiciaire des conventions. [less ▲]

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See detailHomologies entre les deux retrovirus BLV et HTLV-1 et developpement d'une nouvelle approche therapeutique basee sur la levee de la latence virale.
Gillet, Nicolas ULg; Kettmann, Richard ULg; Willems, Luc ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2007), 11(2),

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See detailHomologies to plastid DNA in the nuclear and mitochondrial genomes of potato.
Du Jardin, Patrick ULg

in Theoretical and Applied Genetics (1990), 79(6),

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See detailHomologous and hybrid calcium complexes of A23187 and hypoglycemic sulfonylureas: nuclear magnetic resonance and conformational analysis.
Deleers, M.; Brasseur, Robert ULg; Gelbcke, M. et al

in Journal of Inorganic Biochemistry (1982), 16(3), 215-25

Hypoglycemic sulfonylureas (e.g., gliclazide) are able to transport calcium across hydrophobic domains. Gliclazide and the ionophore A23187 act synergistically upon calcium transport. One calcium atom is ... [more ▼]

Hypoglycemic sulfonylureas (e.g., gliclazide) are able to transport calcium across hydrophobic domains. Gliclazide and the ionophore A23187 act synergistically upon calcium transport. One calcium atom is complexed by either two molecules of sulfonylureas (or A23187) or one molecule each of sulfonylurea and A23187; the existence of such hybrid complexes has been documented by nuclear magnetic resonance. Conformation analysis of the calcium-gliclazide complex suggests close apposition of the toluyl groups in the gliclazide molecules. [less ▲]

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See detailHomologous radioimmunoassay for bovine insulin-like growth factor-binding protein-2 (IGFBP-2)
Portetelle, Daniel ULg; Vleurick, Live; Massart, Serge et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (1998), 2(special issue), 13

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See detailHomologous radioimmunoassay for bovine insulin-like growth factor-binding protein-2 (IGFBP-2).
Vleurick, Lieve; Portetelle, Daniel ULg; Massart, Serge et al

in 3° Internat. Conf. farm Anim. Endocrinol. (1998)

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See detailA homologous radioimmunoassay for canine prolactin: plasma levels during the reproductive cycle
De Coster, R.; Beckers, Jean-François ULg; Beerens, D. et al

in Acta Endocrinologica (1983), 103

A method is described for the purification of canine prolactin, involving preparative isoelectrofocusing. Canine prolactin has a molecular weight of 23 000 daltons, an isoelectric point of 5.7 and ... [more ▼]

A method is described for the purification of canine prolactin, involving preparative isoelectrofocusing. Canine prolactin has a molecular weight of 23 000 daltons, an isoelectric point of 5.7 and exhibits a high degree of homogeneity in polyacrylamide gels stained by means of a silver method. A specific, homologous radioimmunoassay is described using the Bolton-Hunter method for preparation of the labelled ligand, with a sensitivity of 1.1 ng/tube. Basal plasma prolactin levels of 2-4 ng/ml obtained through the oestrous cycle remained fairly constant but a rise of 9 ng/ml was found at the end of disoetrus in nonpregnant bitches. Level also rose 30 days after mating to reach a peak of about 50 ng/ml near parturition and during early lactation. [less ▲]

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