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ORBi Open Repository and Bibliography (306.968 recursos)

In may 2007, the ULg's Administrative Board (joined in June 2007 by the FUSAGx) decided to create an institutional repository and defined a strong institutional self-archiving policy to increase the visibility, accessibility and impact of the University's publications (Board's decision). This decision led to the official launch, in November 2008, of the ORBi platform including both the Academic Bibliography and the Institutional Repository of the Wallonia-Europe University Academy.

Engineering, computing & technology => Electrical & electronics engineering

Mostrando recursos 1 - 20 de 90

  1. Bulk superconducting tube subjected to the stray magnetic field of a solenoid

    Hogan, Kevin; Fagnard, Jean-François; Wera, Laurent; Vanderheyden, Benoît; Vanderbemden, Philippe
    Peer reviewed

  2. A gait cycle partitioning method using a foot-worn accelerometer system

    Boutaayamou, Mohamed; Bruls, Olivier; Denoël, Vincent; Forthomme, Bénédicte; Croisier, Jean-Louis; Verly, Jacques; Garraux, Gaëtan; Schwartz, Cédric
    Peer reviewed

  3. Instrumentation, magnetic and electrical characterization of superconductors

    Vanderbemden, Philippe

  4. Magnetic shielding of open and semi-closed tubes made of bulk superconductors : the role of a cap

    Vanderbemden, Philippe; Wera, Laurent; Hogan, Kevin; Vanderheyden, Benoît; Fagnard, Jean-François; Namburi, D K; Shi, Y H; Cardwell, D A
    Peer reviewed

  5. Model Order Reduction: Application to Electromagnetic Problems

    Paquay, Yannick

  6. Investigation of the shielding properties of a Bi-2212 bulk superconducting tube subjected to an inhomogeneous magnetic field at various temperatures

    Hogan, Kevin; Wera, Laurent; Fagnard, Jean-François; Vanderbemden, Philippe
    Magnetic shielding with bulk superconductors is commonly studied under homogeneous magnetic fields. This configuration simplifies the analysis of the magnetic reaction of the superconductor as the applied magnetic field is known precisely everywhere. In practical applications, however, the magnetic field to be screened is seldom homogeneous. Magnetic shields experience magnetic field gradients and flux lines curvatures that might lead to a deterioration of the shielding properties. In the present work, we investigate experimentally the magnetic shielding properties of a bulk superconducting Bi-2212 tube subjected to an inhomogeneous magnetic field. This study is carried out at various temperatures thanks to a bespoke...

  7. Coupled electromagnetic-fluid modelling of a bulk superconductor cooled by a cryogenic fluid

    Kirsch, Sébastien; Fagnard, Jean-François; Dubois, Charles; Caps, Hervé; Vanderbemden, Philippe; Vanderheyden, Benoît
    The electric and magnetic performance of a superconductor are strongly dependent of its temperature. For that reason, the cooling of the superconductor material is an important matter, especially for bulk superconductors, which favor low heat transfers because of their low thermal conductivity and the large volume to surface ratio. Usually, heat transfers between a bulk superconductor and the cooling fluid is modelled by a simplified law depending on a convective coefficient and the temperature difference between the fluid and the bulk surface. In practice, however, the heat flux depends also on the geometry of the superconductor and its orientation. Its experimental...

  8. Model for the response of superconducting/ferromagnetic structures subjected to crossed fields

    Vanderheyden, Benoît; Fagnard, Jean-François; Hogan, Kevin; Vanderbemden, Philippe
    Bulk (RE)BCO samples can be used as efficient permanent magnets with trapped magnetic flux densities of a few teslas at 77 K. However, their magnetization may decay over time when subjected to time-varying parasitic fields perpendicular to the initial trapped flux density. In this work, we consider hybrid structures made of superconducting pellets and soft ferromagnetic rings or disks and investigate numerically how their magnetization varies under such crossed-field excitations. We consider a finite-element model in the A-V formulation, which is developed for both the full 3D configuration of the system and for a computationally lighter 2D approximation. The models...

  9. Model for the penetration of magnetic flux in Nb superconducting films with lithographically defined indentations and defects due to inhomogeneities

    Vanderheyden, Benoît; Avila Osses, Jonathan; Brisbois, Jérémy; Burger, Loïc; Nguyen, Ngoc Duy; Silhanek, Alejandro
    We consider the penetration of magnetic flux perpendicularly to a Nb superconducting film containing edge indentations and/or defects. The induced currents undergo an abrupt change of direction around the indentations and the defects, giving rise to discontinuity lines (d-lines). It has recently been shown, by means of magneto-optical imaging and numerical models, that the detailed structure of the d-lines generated with lithographically-defined micro-indentations carry information about their size and shape, and vary with temperature [1]. In this talk, we describe the models which can be used to describe the d-lines and discuss the effects of temperature, demagnetization, and flux creep,...

  10. Drilled bulk high-temperature superconductors: enhancing the trapped magnetic flux by filling the holes with a ferromagnetic powder

    Lousberg, Grégory; Fagnard, Jean-François; Ausloos, Marcel; Vanderbemden, Philippe; Vanderheyden, Benoît
    Filling the holes of a drilled bulk high-temperature superconductor (HTS) with a ferromagnetic powder is shown to enhance its trapping properties. We use experimental techniques (Hall probe mapping techniques and magnetization measurements) to characterize the magnetic properties of drilled samples filled with a soft ferromagnetic powder. The analysis is completed by a numerical model based on a 3D finite-element method that involves a conductivity in the form of a power law for the superconducting material, and a constant permeability for the ferromagnetic material. Numerical results confirm the experimental observations, and, in particular, they support the increase of trapped flux after impregnation (max. 40%) that is observed with Hall probe mappings.

  11. Magnetic behaviour of a superconducting hollow cylinder subjected to crossed fields: Experimental and modelling results

    Fagnard, Jean-François; Dirickx, Michel; Vanderbemden, Philippe; Vanderheyden, Benoît
    Experiments are carried out to study the decay of the axial magnetization of a hollow cylinder subjected to a transverse magnetic field varying with a low frequency (a “crossed-fields” configuration). The measured sample is a Bi-2223 cylinder immersed in a bath of liquid nitrogen (T = 77 K). The transverse field is applied with a sinusoidal or a triangular waveform and with a single or a double polarity. Flux-creep effects are subtracted from the magnetization decay. The magnetic induction at the centre of the cylinder is characterized as a function of time; the features of its decay are related to...

  12. AC and heat losses in a superconductor cylinder surrounded by a metallic sheath

    Kirsch, Sébastien; Fagnard, Jean-François; Vanderbemden, Philippe; Vanderheyden, Benoît
    In this work, we study numerically the magneto-thermal properties of a composite cylinder made of a superconducting core surrounded by a metallic sheath and subjected to an axial AC magnetic field . The metal is ohmic and non-magnetic while the superconductor is characterized by an E(J) power law. The system is studied in a regime for which the temperature is non uniform (and hence the current density is varying spatially), in order to investigate heat draining by the cryofluid. The magneto-thermal problem is solved by the Brandt method for the magnetic part, associated with a standard discretization of the stationary...

  13. Model for the decay of the magnetization of a bulk superconductor for different sources of magnetic fields with a transverse component

    Vanderheyden, Benoît; Fagnard, Jean-François; Hogan, Kevin; Vanderbemden, Philippe
    Bulk (RE)BCO samples can be used as efficient trapped-field magnets with surface flux densities of a few teslas. However, their magnetization may decay over time when subjected to time-varying parasitic crossed fields (applied perpendicular to the initially trapped flux density). In this work, we consider and compare the magnetization decays that occur under different types of crossed-field perturbations, mimicking realistic perturbations that are expected in synchronous motors. The model is based on a finite element approach carried in the GetDP environment. The superconductor is modelled with an isotropic E(J) power law and a field-independent current density. Under a magnetic field...

  14. Decentralized Model Predictive Control of Voltage Source Converters for AC Frequency Containment

    Papangelis, Lampros; Debry, Marie-Sophie; Prevost, Thibault; Panciatici, Patrick; Van Cutsem, Thierry
    Peer reviewed

  15. Decentralized Model Predictive Control of Voltage Source Converters for AC Frequency Containment

    Papangelis, Lampros; Debry, Marie-Sophie; Prevost, Thibault; Panciatici, Patrick; Van Cutsem, Thierry
    Peer reviewed

  16. Sparselizard - the user friendly finite element c++ library

    Halbach, Alexandre
    This is the documentation for sparselizard - the user friendly finite element c++ library

  17. Sparselizard - the user friendly finite element c++ library

    Halbach, Alexandre
    This is the documentation for sparselizard - the user friendly finite element c++ library

  18. Agent-based Identification and Control of Voltage Emergency Situations

    Robitzky, Lena; Weckesser, Tilman; Häger, Ulf; Rehtanz, Christian; Van Cutsem, Thierry
    Peer reviewed

  19. Hammerstein kernels identification by means of a sine sweep technique applied to nonlinear audio devices emulation

    Schmitz, Thomas; Embrechts, Jean-Jacques
    Peer reviewed

  20. Hammerstein kernels identification by means of a sine sweep technique applied to nonlinear audio devices emulation

    Schmitz, Thomas; Embrechts, Jean-Jacques
    Peer reviewed

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