Recursos de colección

ORBi Open Repository and Bibliography (301.662 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.

Physical, chemical, mathematical & earth Sciences

Mostrando recursos 1 - 20 de 570

  1. Strongly interacting dark matter doesn't explain the DAMA signal

    Laletin, Maxim

  2. Rapid protein structure determination using experimental NMR data

    Wanko Nembot, Alexis Marius
    The knowledge of the tridimensional structure of a protein is essential to design drugs, to predict protein function and to study mechanism of protein function. 3D structure can be determined using two experimental techniques: X-Ray and NMR. However, these techniques have limitations: they are time consuming, manually intensive and sometime technically difficult. Due to these limitations, different approaches that combine the strength of computer and sparse experimental NMR data such as backbone chemical shifts, NOEs distances and residual dipolar couplings have been proposed for the determination of 3D protein structure. Among these experimental NMR data, backbone chemical shifts are the...

  3. Towards a development of iron phosphate-based materials as positive and negative electrodes for Li-ion batteries

    Karegeya, Claude
    The design, synthesis and electrochemical characterization of new electrode materials hold the key for fundamental advances in energy conversion and storage technologies. Polyanionic compounds have been heavily investigated as possible electrode materials in lithium- and sodium-ion cells. This thesis focused on the design, synthesis, size and morphology tailoring of iron phosphate based electrode materials in order to enhance their electrochemical properties. Four iron phosphate-based electrode materials classified in three groups: Na2Mn1.5Fe1.5(PO4)3, NaxMxFe(3-X)(PO4)3 (X=1.25 when M=Ni and x=1.5 for M= Mn) and Fe1.19(PO4)(OH)0.57(H2O)0.43, were investigated in this work. All these compounds were obtained through wet chemical (hydrothermal or solvothermal) synthesis routes....

  4. Comparison of rapid protein structure determination approaches driven by experimental NMR data

    Wanko Nembot, Alexis Marius
    The knowledge of the tridimensional structure of a protein is essential to design drugs, to predict protein function and to study mechanism of protein function. 3D structure can be determined using two experimental techniques: X-Ray and NMR. However, these techniques have limitations: they are time consuming, manually intensive and sometime technically difficult. Due to these limitations, different approaches that combine the strength of computer and sparse experimental NMR data have been proposed to determine rapidly 3D protein structure. Thus different approaches that use sparse NMR experimental NMR data such as backbone chemical shifts, incomplete sets of NOEs distances and residual...

  5. DC and AC shielding properties of bulk high-Tc superconducting tubes

    Fagnard, Jean-François; Denis, Samuel; Lousberg, Grégory; Ausloos, Marcel; Vanderheyden, Benoît; Vanderbemden, Philippe
    In this work we have studied numerically and experimentally the magnetic flux penetration in high-Tc superconducting tube subjected to a uniform magnetic field parallel to its long axis. This study is carried in view of designing low-frequency magnetic shields by exploiting the diamagnetic properties of high-Tc superconducting ceramics. We have measured the field attenuation for DC and AC applied fields (40 Hz < f < 400 Hz) and we have confronted data with computer modeling of the field distribution in the hollow of the tube. The numerical model is based on an algorithm proposed by Brandt (Phys. Rev. B 58,...

  6. Temperature dependence of HTS magnetic shielding properties: Measurements on Pb-doped Bi-2223 hollow cylinders submitted to axial magnetic fields

    Fagnard, Jean-François; Dirickx, Michel; Ausloos, Marcel; Vanderheyden, Benoît; Vanderbemden, Philippe
    Measurements of the magnetic shielding properties of Pb-doped Bi-2223 hollow cylinders submitted to an axial magnetic field have been carried out at several temperatures in the range 10 K - 95 K. The amplitude of the internal magnetic field was probed using a high sensitivity 3-axis Hall sensor. We have studied the dependence of the shielding factor (the ratio of the applied magnetic field over the internal magnetic field) with respect to the sweep rate of the applied field at several temperatures. The experimental results were compared to a 2-D modelling based on Brandt’s algorithm [1, 2] involving a non-linear...

  7. Study of the magnetic shielding ability in relation with the non linear E(J) relationship of melt cast Bi-2212 tubes under DC axial magnetic fields

    Fagnard, Jean-François; Dirickx, Michel; Elschner, Stephan; Bock, Joachim; Vanderheyden, Benoît; Vanderbemden, Philippe
    In this work, we aim at describing as widely as possible the shielding properties and the E(J) relationship of Bi-2212 tubes from non-destructive measurements on a whole cylinder. First, the threshold magnetic induction below which the shielding occurs, Blim, is measured in a large temperature range between 10 K and 77 K. The temperature dependence of Blim is compared to that of similar superconducting hollow cylinders made of Bi-2223 previously studied in [Fagnard J-F et al. Supercond. Sci. Technol. 22 (2009) 105002] and shows that the magnetic shielding capabilities of Bi-2212 below T = 60 K can exceed those of...

  8. Study of the magnetic shielding ability in relation with the non linear E(J) relationship of melt cast Bi-2212 tubes under DC axial magnetic fields.

    Fagnard, Jean-François; Elschner, Stephan; Bock, Joachim; Dirickx, Michel; Vanderheyden, Benoît; Vanderbemden, Philippe
    In this work, we aim at describing as widely as possible the shielding properties and the E(J) relationship of Bi-2212 tubes from non-destructive measurements on a whole cylinder. First, the threshold magnetic induction below which the shielding occurs, Blim, is measured in a large temperature range between 10 K and 77 K. The temperature dependence of Blim is compared to that of similar superconducting hollow cylinders made of Bi-2223 previously studied in [Fagnard J-F et al. Supercond. Sci. Technol. 22 (2009) 105002] and shows that the magnetic shielding capabilities of Bi-2212 below T = 60 K can exceed those of...

  9. Screening of axial DC magnetic fields by using superconducting loops of second generation coated conductors without joints

    Fagnard, Jean-François; Dirickx, Michel; Vanderheyden, Benoît; Vanderbemden, Philippe; Barnes, P.N.; Levin, Georges
    The performances of second generation (2G) YBCO coated conductors for screening DC magnetic fields at 77 K are investigated experimentally. An uninterrupted superconducting path is achieved by splitting two sections of a slit 2G tape in order to obtain a loop without joint. Several loops are stacked together to obtain a coil acting as a magnetic screen. Persistent currents in this coil are shown to shield efficiently magnetic fields that are applied at very low sweep rates (500 @T/s). The shielding properties are characterized by measuring the shielding factor of the screen, i.e. the ratio between the magnetic field with...

  10. Magnetic shielding properties of a superconducting hollow cylinder: Influence of a vertical or a horizontal slit

    Fagnard, Jean-François; Dirickx, Michel; Elschner, Stephan; Hobl, Achim; Vanderheyden, Benoît; Vanderbemden, Philippe
    The magnetic shielding properties under both axial and transverse DC magnetic fields are measured at the liquid nitrogen temperature (77 K) on Bi-2212 hollow cylinders obtained by Melt Cast Process. The characterized samples are cut by a slit along either a vertical (parallel to the cylinder axis) or a horizontal (perpendicular to the cylinder axis) plane. The sample with the vertical slit is subjected to a transverse magnetic field whose the direction is varied between 0° and 90° with respect to the normal of the slit plane. The measurements show that there is no influence of the presence of the...

  11. Non-destructive characterization of DC volume magnetic properties of large, bulk (RE)BCO superconducting samples

    Fagnard, Jean-François; Philippe, Matthieu; Vanderheyden, Benoît; Vanderbemden, Philippe
    The development of large, single grain bulk superconductors by melt processing techniques has generated a need to characterize samples magnetically over large dimensions, exceeding typically 20 mm in diameter. The usual magnetic characterization gives relies on miniature Hall probe mapping and gives information about the field distribution above the sample surface. If volume properties are required (e.g. M(H) loops), the sample needs to be cut in smaller pieces, since the DC magnetic characterization systems for measurements at cryogenic temperatures generally accommodate samples of relatively small size (typically < 5-10 mm diameter). In this work we describe how the M(H) loops...

  12. Crossed field effect measured on a GdBCO pellet at various temperatures below 77 K

    Fagnard, Jean-François; Debois, Simon; Morita, Mitsuru; Nariki, Shinya; teshima, Hidekazu; Vanderheyden, Benoît; Vanderbemden, Philippe
    In engineering applications, superconducting bulk materials might be subjected to cycles of variable magnetic fields transverse to their trapped field which can cause a significant demagnetization. Up to now, several studies have been carried out on bulk superconducting pellets in order to characterize this so-called “crossed fields” effect at 77 K only. When attempting to carry out experiments at lower temperature, the issue is that the commercial systems with rotating sample holders do not accommodate sample having a larger size than few mm³. Therefore samples have to be cut from a larger pellet to be characterized. We designed an insertion tool...

  13. ‘Quality by Design’ approach for the analysis of impurities in pharmaceutical drug products and drug substances

    Dispas, Amandine; Avohou, Tonakpon Hermane; Lebrun, Pierre; Hubert, Philippe; Hubert, Cédric
    Peer reviewed

  14. Experimental study of GdBCO pellets subjected to small transverse alternating magnetic fields at very low frequency: Evidence of saturation of the axial magnetization decay

    Fagnard, Jean-François; Kirsch, Sébastien; Teshima, Hidekazu; Morita, Mitsuru; Vanderheyden, Benoît; Vanderbemden, Philippe
    Due to their ability to trap large magnetic inductions, bulk (RE)BCO materials (where RE stands for rare-earth ion) can be used as powerful permanent magnets. Previous works have shown that the magnetization of a bulk superconductor can be destroyed by the presence of an ac magnetic field applied transversally to the remnant magnetization. Up to now, the exact process of this magnetization decay is not completely understood, i.e. it is not clear if the decay is only due to a redistribution of the superconducting currents in the volume of the pellet or if a part of this decay can be...

  15. Decay of the axial magnetization of GdBCO pellets subjected to small transverse alternating magnetic fields.

    Fagnard, Jean-François; Kirsch, Sébastien; Teshima, Hidekazu; Morita, Mitsuru; Vanderheyden, Benoît; Vanderbemden, Philippe
    Bulk (RE)BCO materials (where RE denotes a rare-earth ion) are known to be used as strong permanent magnets in various engineering devices, such as magnetic bearings or rotating machines. In so doing, the bulk pellet is usually magnetized along its c-axis and a permanent magnetic moment is trapped. In real application, however, the pellet is likely to be subjected to small parasitic magnetic fields that cause a decay of the permanent magnetic moment. The most severe effects arise when the pellets are subjected to ac magnetic field cycles that are perpendicular to their c- axis (“crossed-fields” configuration). Our previous works...

  16. Comparison of the magnetization decay due to crossed or rotated magnetic field measured on a Ferromagnet disk/GdBCO pellet structure

    Fagnard, Jean-François; Morita, Mitsuru; Teshima, Hidekazu; Vanderheyden, Benoît; Vanderbemden, Philippe
    Superconducting (SC) bulk materials are commonly used as permanent magnets in synchronous rotating machines. When the machine is in operation, the bulk materials that are placed in the machine rotor can experience a certain misalignment with the magnetic field generated by the stator. This situation is likely to happen during transients or non-ideal behavior of the machine: the angle between the stator field and the SC magnetization can change because of a sudden change of mechanical load or vibrations of the device. The consequence is that the SC pellet can be subjected to a transverse component of magnetic field which...

  17. L'astronomie dans le monde - 09/2016

    Manfroid, Jean
    Vénus - Phobos et Deimos - Une nouvelle planète naine au-delà de Neptune - Ondes gravitationnelles - L’oxygène de la comète 67P - Averse intergalactique - Méthanol protoplanétaire - TRAPPIST-1 - Les jupiters chaudes de M67

  18. Impact of non-stationary mesoscale eddies in the Black Sea on vertical water structure

    Karimova, Svetlana

  19. Submesoscale eddies seen by spaceborne radar

    Karimova, Svetlana; Gade, Martin
    In the present study, synthetic aperture radar (SAR) imagery was used to derive statistics on spiral eddies in the eastern Mediterranean and Black seas. The dataset used consists of about 1700 medium resolution Envisat ASAR and ERS-2 SAR images obtained in 2009-2011. A comprehensive analysis of the eddy occurrence in SAR imagery was performed, thus providing insight into the eddies’ spatial and temporal distribution and the eddy ‘density’, i.e. the number of eddies per square unit. The analyses of the temporal variability of the derived above-mentioned statistical parameters revealed their strong seasonality, whose main reasons were suggested to be the...

  20. Non-stationary eddies in the Black Sea as seen by satellite infrared and visible imagery

    Karimova, Svetlana
    Peer reviewed

Aviso de cookies: Usamos cookies propias y de terceros para mejorar nuestros servicios, para análisis estadístico y para mostrarle publicidad. Si continua navegando consideramos que acepta su uso en los términos establecidos en la Política de cookies.