Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
See detailMorphologie urbaine et économie des services collectifs
Halleux, Jean-Marie ULg; Lambotte, Jean-Marc ULg

in Qualité environnementale des bâtiments : quels bénéfices ? (2005)

Detailed reference viewed: 31 (6 ULg)
See detailLa morphologie verbale en néo-égyptien (de la 18e à la 25e dynastie)
Winand, Jean ULg

Doctoral thesis (1989)

Detailed reference viewed: 49 (1 ULg)
Peer Reviewed
See detailMorphologie, distribution et écologie comparées d'Amblystegium tenax et d'A. fluviatile en Belgique
Vanderpoorten, Alain ULg; Empain, Alain ULg

in Belgian Journal of Botany (1999), 132(1), 3-12

Detailed reference viewed: 58 (0 ULg)
See detailMorphology and dynamics of the Io footprint
Bonfond, Bertrand ULg

Scientific conference (2008, June 03)

Detailed reference viewed: 2 (0 ULg)
Full Text
See detailMorphology and dynamics of the Io UV footprint
Bonfond, Bertrand ULg

Doctoral thesis (2009)

The Io UV footprint (IFP) is one of the most spectacular signatures of the Io-Jupiter interaction. It consists of several auroral spots and an extended tail which are located close to the feet of the ... [more ▼]

The Io UV footprint (IFP) is one of the most spectacular signatures of the Io-Jupiter interaction. It consists of several auroral spots and an extended tail which are located close to the feet of the magnetic field lines passing through Io in each hemisphere. The purpose of the present study is to demonstrate that a careful analysis of the Io UV footprint based on observations acquired with the STIS and ACS high resolution and high sensitivity FUV cameras on board the Hubble Space Telescope can provide us with essential information on the ongoing physical processes. The thesis is organized around basic questions: “What is the Io footprint?”, “Where is the Io footprint?”, “How high is the Io footprint?”, “How big is the Io footprint?” and finally: “How bright is the Io footprint?” The answers to these questions have profound implications for the understanding of the phenomenon. Among the most important results of this work is the unexpected finding of a faint auroral spot appearing upstream of the main Io spot in one hemisphere while only downstream spots are seen in the opposite hemisphere. The detailed study of the evolution of the inter-spot distances puts previous models describing the footprint morphology under question. We propose a new interpretation which involves that some spots are caused by electrons accelerated away from the planet along the field lines in one hemisphere, crossing the equatorial plane in the form of electron beams and precipitating in the opposite hemisphere, creating the so-called Trans-hemispheric Electron Beam (TEB) spots. The information provided by the position of the satellite footprints is not restricted to the interaction between the moon and the Jovian magnetosphere. The analysis of the footpaths of Io, Europa and Ganymede helped us to further constrain the magnetic field models, notably through the identification of a large magnetic anomaly in the northern hemisphere. Additionally, the study of the speed of the Io footprint along its reference contour suggests that a second anomaly regions may also exist in the North. In this work, we present a new and direct method to measure the altitude of the different footprint features. The main spot and the tail emissions have a peak altitude of 900 km while the peak altitude of the Trans-hemispheric Electron Beam spot is 700 km. These results suggest that the main spot and tail emissions are caused by the precipitation of electrons with a mean energy around 1 keV, far lower than the 55 keV value previously derived from spectral measurements. The vertical extent of these emissions is surprisingly broad (scale height ~400 km) and is best fitted with an incoming kappa electron energy distribution (spectral index ~2.3). This suggests that the electron acceleration is supplied by processes related to inertial Alfvén waves rather than by quasi-static potentials as proposed by some theoretical models. The size of the main footprint spot is carefully estimated on a much larger image sample than before: its length along the footpath is ~900 km while its width perpendicular to the footpath is <200 km. Larger lengths are sometimes observed but in that case, they are attributed to the mix of individual spots. The spot length is larger than the projected diameter of Io around the magnetic field lines but is consistent with recent simulations. As far as the Io footprint brightness is concerned, variations on two timescales have been studied. On timescales of minutes, systematic brightness fluctuation on the order of 30% (and going up to 50%) are observed. Additionally, cases of simultaneous variations of the main and the TEB spots are reported, which suggests that the process that triggers these fast variations is located close to the planet. Variations of the main spot brightness with the System III longitude of Io are also analyzed. Our new measurement method fully considering the multi-spot structure of the IFP and the real geometry of the observations provides more accurate estimates for the precipitating energy flux (between 100 and 500 mW/m for the main spot). The main spot brightness peaks at 110° and 290° longitude, which could be attributed either to an enhanced interaction strength when Io is near the dense torus center or to spots merging which is also observed to occur in these sector. Nevertheless, strong North-South asymmetries are also observed, which suggests that the surface magnetic field strength also influences the spots brightness. [less ▲]

Detailed reference viewed: 116 (29 ULg)
Full Text
Peer Reviewed
See detailMorphology and dynamics of Venus oxygen airglow from Venus Express/Visible and Infrared Thermal Imaging Spectrometer observations
Hueso, R.; Sánchez-Lavega, A.; Piccioni, G. et al

in Journal of Geophysical Research. Planets (2008), 113

Images obtained by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS)-M channel instrument onboard Venus Express have been used to retrieve maps and apparent motions of the O[SUB]2[/SUB] ([SUP ... [more ▼]

Images obtained by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS)-M channel instrument onboard Venus Express have been used to retrieve maps and apparent motions of the O[SUB]2[/SUB] ([SUP]1[/SUP]Delta) infrared nightglow on Venus at 1.27 mum. The nightglow distribution is highly inhomogeneous with the regions of brightest emission generally located at low latitudes near the midnight meridian. Unexpectedly some orbits show also intense airglow activity over the south polar region. The spatially resolved airglow is spectacularly variable not only in its morphology and intensity but also in the apparent motions of the airglow small- and large-scale structures. Visual tracking of the bright features allowed to obtain mean zonal and meridional motions related to the subsolar to antisolar circulation. The zonal velocity is dominated by an intense prograde jet (contrary to the retrograde planetary rotation) from dawn to midnight extending up to 22 hours in local time with lower velocities and reversed sign from dusk. Typical zonal velocities range between +60 (prograde) to -50 (retrograde) m/s, whereas most meridional velocities range from -20 (poleward) to +100 m/s (equatorward) with an average meridional circulation of +20 m/s toward low latitudes. The brightest small-scale (~100 km) features appear correlated with locations of apparent convergence which may be a signature of compression and downwelling, whereas this is not evident for the large-scale structures suggesting slow subsidence over large areas mixed with horizontal motions. We argue that part of the tracked motions are representative of real motions at the mesosphere over an altitude range of 95-107 km. [less ▲]

Detailed reference viewed: 13 (4 ULg)
See detailMorphology and electrical conductivity of poly(propylene)/multi-walled carbon nanotubes nanocomposites foams compatibilized by poly(propylene) -graft-maleic anhydride (PP-g-MA)
Tran, Minh Phuong ULg; Detrembleur, Christophe ULg; Alexandre, Michaël et al

Poster (2013, September 09)

The agglomerate of carbon nanotubes (CNTs) in poly(propylene) (PP) matrix often results in low electrical conductivity and poor mechanical properties. In order to improve the dispersion of CNTs, different ... [more ▼]

The agglomerate of carbon nanotubes (CNTs) in poly(propylene) (PP) matrix often results in low electrical conductivity and poor mechanical properties. In order to improve the dispersion of CNTs, different amounts of compatibilizer based on poly(propylene-graft-maleic anhydride) (PP-g-MA) were added in the PP matrix. Carbon nanotubes materbatches pre-dispersed at a high loading in the compatibilizer were used to create the samples used in this study. The nanocomposites of PP/PP-g-MA/CNTs were then foamed in supercritical carbon diozide (scCO2) followed by analysis of the foam morphology and the electrical conductivity. The presence of PPgMA did not significantly change the foam morphology, which exhibits good homogeneity and highly uniform closed-cells with penta-heptagonal cell-form. The expansion volume of the foams is not adversely affected by the addition of the compatibilizer; very high expansion volume (around 15 - 25 times) was achieved. The most interesting point is that the PP-PPgMA - 4wt%CNTs foams show a significantly higher electrical conductivity than the uncompatibilized PP-4wt%CNTs at the same volume percent content of CNTs [less ▲]

Detailed reference viewed: 46 (6 ULg)
Full Text
Peer Reviewed
See detailMorphology and mechanical properties of bisphenol A polycarbonate/poly(styrene-co-acrylonitrile) blends based clay nanocomposites
Lin, Demiao; Boschetti-de-Fierro, Adriana; Alexandre, Michaël ULg et al

in Composites Science & Technology (2011), 71(16), 1893-1897

Two organic modified clays (Cloisite®30B (CL30B) and PCL/Cloisite®30B masterbatch (MB30B)) were used to improve the mechanical properties of polycarbonate (PC)/poly (styrene-co-acrylonitrile) (SAN) blends ... [more ▼]

Two organic modified clays (Cloisite®30B (CL30B) and PCL/Cloisite®30B masterbatch (MB30B)) were used to improve the mechanical properties of polycarbonate (PC)/poly (styrene-co-acrylonitrile) (SAN) blends. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements of the melt blended nanocomposites revealed that partially exfoliated and partially degraded structure was obtained and the clay platelets were located mostly in the SAN phase and at the two-phase boundary. Dispersion of the clay platelets is better when MB30B were used. The mechanical properties of the clays filled nanocomposites vary accordingly and when MB30B is used better mechanical properties can be achieved. Tensile strength increases 41% at maximum as the CL30B loading is 5 wt.%, while elongation at break decreases dramatically. Impact strength can be improved up to 430% compared to the pure blend when 1 wt.% MB30B was used. [less ▲]

Detailed reference viewed: 69 (5 ULg)
Full Text
Peer Reviewed
See detailMorphology and mechanical properties of poly(methylmethacrylate)-b-poly(alkylacrylate)-b-poly(methylmethacrylate)
Tong, J. D.; Leclère, Philippe; Doneux, C. et al

in Polymer (2001), 42(8), 3503-3514

A series of well-defined poly(methylmethacrylate) (PMMA)-b-poly(alkylacrylate)-b-PMMA triblock copolymers (MAM) has been synthesized by transalcoholysis of PMMA-b-poly(tert-butylacrylate)-b-PMMA ... [more ▼]

A series of well-defined poly(methylmethacrylate) (PMMA)-b-poly(alkylacrylate)-b-PMMA triblock copolymers (MAM) has been synthesized by transalcoholysis of PMMA-b-poly(tert-butylacrylate)-b-PMMA precursors by alkyl alcohols. The molecular weight (MW) of the outer PMMA blocks is in the 10,000-50,000 range, compared to 50,000-200,000 for the inner poly(alkylacrylate) block. Phase separation, as studied in direct space by atomic force microscopy, is observed for all the investigated triblock copolymers, except for the PMMA-b-poly(ethylacrylate)-b-PMMA and the PMMA-b-poly(n-propylacrylate)-b-PMMA triblocks of 10,000-50,000-10,000 MW. The ultimate tensile strength measured for the MAM triblocks is strongly dependent on the MW between chain entanglements for the central block. The tensile behavior is however affected by the partial miscibility of the outer and inner blocks when the PMMA MW is low. When this situation prevails, it makes the melt processing possible at temperatures lower than 200°C. [less ▲]

Detailed reference viewed: 30 (0 ULg)
Full Text
Peer Reviewed
See detailMorphology and properties of SAN-clay nanocomposites prepared principally by water-assisted extrusion
Mainil, Michaël; Urbanczyk, Laetitia ULg; Calberg, Cédric ULg et al

in Polymer Engineering & Science (2010), 50(1), 10-21

An efficient extrusion process involving the injection of water while processing was used to prepare poly(styrene-co-acrylonitrile) (SAN) / clay nanocomposites with a high degree of nanoclay delamination ... [more ▼]

An efficient extrusion process involving the injection of water while processing was used to prepare poly(styrene-co-acrylonitrile) (SAN) / clay nanocomposites with a high degree of nanoclay delamination. The usefulness of water-assisted extrusion is highlighted here, in comparison with classical extrusion and roll mill processes. Cloisite® 30B (C30B), a montmorillonite clay organomodified with alkylammonium cations bearing 2-hydroxyethyl chains, and pristine montmorillonite were melt blended with SAN (25wt% AN) in a semi-industrial scale extruder specially designed to allow water injection. XRD analysis, visual and TEM observations were used to evaluate the quality of clay dispersion. The relationship between the nanocomposite morphology and its mechanical and thermal properties was then investigated. The superiority of the SAN/C30B nanocomposite extruded with water has been evidenced by cone calorimetry tests and thermogravimetric measurements (TGA). These analyses showed a substantial improvement of the fire behavior and the thermal properties, while a 20% increase of the Young modulus was recorded. [less ▲]

Detailed reference viewed: 144 (7 ULg)
Full Text
Peer Reviewed
See detailMorphology and rheology of poly(methyl methacrylate)-block-poly(isooctyl acrylate)-block-poly(mehtyl methacrylate) triblock copolymers, and potential as thermoplastic elastomers
Tong, Jiang-Dong; Leclère, Philippe; Rasmont, A. et al

in Macromolecular Chemistry and Physics (2000), 201(12), 1250-1258

The phase morphology and rheological properties of a series of poly(methyl methacrylate)-block-poly(isooctyl acrylate)-block-poly(methyl methacrylate) triblock copolymers (MIM) have been studied. These ... [more ▼]

The phase morphology and rheological properties of a series of poly(methyl methacrylate)-block-poly(isooctyl acrylate)-block-poly(methyl methacrylate) triblock copolymers (MIM) have been studied. These copolymers have well-defined molecular structures, with a molecular weight (MW) of poly(methyl methacrylate) (PMMA) in the range of 3 500-50 000 and MW of poly(isooctyl acrylate) (PIOA) ranging from 100 000 to 140 000. Atomic force microscopy with phase detection imaging has shown a two-phase morphology for all the MIM copolymers. The typical spherical, cylindrical, and lamellar phase morphologies have been observed depending on the copolymer composition. MIM consisting of very short PMMA end blocks (MW 3 500-5 000) behave as thermoplastic elastomers (TPEs), with however an upper-service temperature higher than the traditional polystyrene-block-polyisoprene-block-polystyrene TPEs (Kraton D1107). A higher processing temperature is also noted, consistent with the higher viscosity of PMMA compared to PS. [less ▲]

Detailed reference viewed: 57 (3 ULg)
Full Text
Peer Reviewed
See detailMorphology and seasonal variations of global auroral proton precipitation observed by IMAGE-FUV
Coumans, Valérie ULg; Gérard, Jean-Claude ULg; Hubert, Benoît ULg et al

in Journal of Geophysical Research. Space Physics (2004), 109(A12),

Observations with the FUV imagers on board the IMAGE satellite have been used to map the auroral electron and proton energy fluxes during the summer and winter solstices of 2000, in order to construct a ... [more ▼]

Observations with the FUV imagers on board the IMAGE satellite have been used to map the auroral electron and proton energy fluxes during the summer and winter solstices of 2000, in order to construct a statistical view of the global auroral proton precipitation. The distribution for electrons compare well both in morphology and in magnitude with those obtained previously with the Polar-UVI instruments and with an empirical auroral precipitation model based on DMSP data. The proton morphology also closely resembles the statistical ion oval derived from DMSP data, showing a "C-shaped'' morphology with a minimum located in the morning sector. The precipitation proton auroral power is on the order of 2.2 GW for an average Kp value of 2, also in close agreement with the values of the DMSP empirical model. The FUV data also reveal the presence of seasonal effects in the proton precipitation. Specifically, the latitudinal width of the proton oval is larger in summer than in winter so that the globally precipitated proton power is 1.5 times higher in summer than in winter. The occurrence probability of intense proton auroras (with energy flux >0.5 mW m(-2)) is also shown to be nearly three times higher in summer than in winter. This seasonal effect in the proton precipitation contrasts with those observed for electrons, where intense electron events occur more often in winter than in summer. We discuss a mechanism that may account for these results based on the presence of field-aligned potential drops which accelerate auroral electrons downward in regions of upward directed field-aligned current, while suppressing the precipitating magnetospheric proton flux. The presence of such field-aligned potentials is dependent on the differing solar illumination in winter and summer. [less ▲]

Detailed reference viewed: 11 (3 ULg)
Peer Reviewed
See detailMorphology and time variation of the Jovian Far UV aurora: Hubble Space Telescope observations
Gérard, Jean-Claude ULg; Dols, Vincent; Paresce, Francesco et al

in Journal of Geophysical Research (1993), 98

High spatial resolution images of the north polar region of Jupiter have been obtained with the Faint Object Camera (FOC) on board the Hubble Space Telescope (HST). The first set of two images collected ... [more ▼]

High spatial resolution images of the north polar region of Jupiter have been obtained with the Faint Object Camera (FOC) on board the Hubble Space Telescope (HST). The first set of two images collected 87 min apart in February 1992 shows a bright (approximately or equal to 180 kR) emission superimposed on the background in rotation with the planet. Both Ly alpha images show common regions of enhanced emission but differences are also observed, possibly due to temporal variations. The second group of images obtained on June 23 and 26, 1992 isolates a spectral region near 153 nm dominated by the H2 Lyman bands and continuum. Both pictures exhibit a narrow arc structure fitting the L = 30 magnetotail field line footprint in the morning sector and a broader diffuse aurora in the afternoon. They show no indication of an evening twilight enhancement. Although the central meridian longitudes were similar, significant differences are seen in the two exposures, especially in the region of diffuse emission, and interpreted as signatures of temporal variations. The total power radiated in the H2 bands is approximately or equal to 2 x 10[SUP]12[/SUP] W, in agreement with previous UV spectrometer observations. The high local H2 emission rates (approximately 450 kR) imply a particle precipitation carrying an energy flux of about 5 x 10[SUP]-2[/SUP] W/sq m. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailMorphology informed by phylogeny reveals unexpected patterns of species differentiation in the aquatic moss Rhynchostegium riparioides s.l
Hutsemékers, Virginie; Vieira, C; Ros, RM et al

in Molecular Phylogenetics & Evolution (2012), 62

Detailed reference viewed: 9 (0 ULg)
Full Text
Peer Reviewed
See detailMorphology of core-shell-corona aqueous micelles: II. Addition of core-forming homopolymer
Lei, Liangcai C; Gohy, Jean-François; Willet, Nicolas ULg et al

in Polymer (2004), 45(13), 4375-4381

The poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) triblock copolymer PS200-b-P2VP(140)-b-PEO590, where the subscripts refer to the number average degrees of polymerization, forms ... [more ▼]

The poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) triblock copolymer PS200-b-P2VP(140)-b-PEO590, where the subscripts refer to the number average degrees of polymerization, forms spherical micelles in water, that consist of a PS core, a pH-responsive P2VP shell and a PEO corona. This triblock has been added with homo-PS before micellization in order to increase the volume fraction of the core-forming block. The length of the added homo-PS has been varied with respect to the length of the PS core-forming block: much shorter, much longer and approximately the same. The structure of the micelles has been investigated by transmission electron microscopy, static and dynamic light scattering. Homo-PS phase separates whenever its length is larger than the one of the PS core-forming chains; otherwise this phenomenon occurs beyond a critical concentration that depends on molecular weight. The addition of homo-PS has no influence on the morphology of the micelles and on the characteristic size of both the PS core and the P2VP shell, although the hydrodynamic diameter of the micelles is decreased. Substitution of styrene for homopolystyrene results in transition from a spherical to a dominant rod-like morphology. (C) 2004 Published by Elsevier Ltd. [less ▲]

Detailed reference viewed: 80 (4 ULg)
See detailThe morphology of equatorial electron beams at Io
Jacobsen, S.; Saur, J.; Neubauer, F. M. et al

Conference (2009, July 27)

Detailed reference viewed: 7 (1 ULg)
Peer Reviewed
See detailThe morphology of equatorial Mg/plus/ ion distribution deduced from 2800-A airglow observations
Gérard, Jean-Claude ULg; Rusch, D. W.; Hays, P. B. et al

in Journal of Geophysical Research (1979), 84

The Visible Airglow Experiment on the Atmosphere Explorer E satellite has observed the resonantly scattered emission from Mg II at 2800 A in the equatorial ionosphere. Altitude profiles of the Mg(plus ... [more ▼]

The Visible Airglow Experiment on the Atmosphere Explorer E satellite has observed the resonantly scattered emission from Mg II at 2800 A in the equatorial ionosphere. Altitude profiles of the Mg(plus) ion distribution have been obtained from the inversion of the surface brightness measurements made on spinning orbits. These data show a daytime metallic ion layer between 150 and 200 km developing in the early morning and reaching about 100 ions/cu cm in the afternoon. Mg(plus) ions are also seen in the F 2 region mostly in the late afternoon hours within a few degrees of the dip equator. The study of the vertical column density measured in the despun mode indicates that the amount of Mg(plus) in the F region is most variable in the afternoon hours at low dip latitudes. These results can be explained in part by the diurnal variation of the E x B drift velocity which lifts the metallic ions up into the F region. The observations suggest that the vertical polarization electric field is not the primary transport mechanism extracting the Mg(plus) ions from the low-altitude source layer. [less ▲]

Detailed reference viewed: 8 (0 ULg)
Full Text
Peer Reviewed
See detailMorphology of Flux Avalanches in Patterned Superconducting Films
Zadorosny, R; Colauto, F; Motta, M et al

in Journal of Superconductivity & Novel Magnetism (2013), 26

It is well known that under certain circumstances, magnetic fields applied perpendicularly to the plane of superconducting films can trigger flux avalanches. In such cases the penetration has a tree-like ... [more ▼]

It is well known that under certain circumstances, magnetic fields applied perpendicularly to the plane of superconducting films can trigger flux avalanches. In such cases the penetration has a tree-like profile. However, in samples where a regular array of antidots, ADs, is present, the avalanches follow the rows of ADs as if they were guiding lines for the abrupt penetration. In this work we used the magneto-optical imaging technique to study the morphology of flux avalanches in two Nb films with a square lattice of square ADs, each one with a different lateral size, and a plain film for reference. We show that the morphology of the flux avalanches is greatly influenced by the size of the interstitial region. [less ▲]

Detailed reference viewed: 32 (1 ULg)