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See detailImage politique et rapports de farce: L'exemple de la "Daerdenmania"
Devresse, Jenifer ULg

in Veyrat-Masson, Isabelle; Denis, Sébastien; Sécail, Claire (Eds.) Sous les images, la politique... Presse, cinéma, télévision, nouveaux médias (XXe-XXIe siècle) (2014)

Narguant les douces utopies démocratiques projetées sur les dispositifs des NTIC, les nouvelles pratiques liées à l’Internet font la part belle au divertissement, et la politique n’y échappe guère ; en ... [more ▼]

Narguant les douces utopies démocratiques projetées sur les dispositifs des NTIC, les nouvelles pratiques liées à l’Internet font la part belle au divertissement, et la politique n’y échappe guère ; en témoigne notamment la fréquentation considérable des formes virtuelles du bêtisier politique (vidéos Youtube, etc.), devançant de loin celle des sites politiques ou citoyens. À cet égard, le cas de la « Daerdenmania » est particulièrement interpellant. Le socialiste belge Michel Daerden, baptisé « le Gainsbourg de la politique », connaît grâce à Internet une popularité internationale surprenante qui ne doit rien assurément à ses qualités proprement politiques, mais plutôt à ses qualités de pitre qui en font le héros d’une foultitude de plaisanteries. Or ce phénomène, bien plus qu’une exception à la belge, ne serait-il pas le révélateur d’un mouvement plus général, lié à une personnalisation du politique à la fois exacerbée et transfigurée par les usages émergents des NTIC ? L’exemple des images « daerdenmaniaques » permet d’explorer quelques modalités du rapport contemporain à la politique et témoignerait, non d’un renouveau de l’engagement citoyen dans les rapports de force politiques, mais au contraire d’un désengagement en termes de rapport de farce à la chose politique. En ce sens, ces formes communes de dérision signifieraient l’endormissement croissant de la possibilité du jugement critique, proprement politique, au profit d’une communauté émotionnelle. [less ▲]

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See detailIMAGE PROCESSING FOR BUBBLE IMAGE VELOCIMETRY IN SELF-AERATED FLOWS
Bung, Daniel B.; Valero Huerta, Daniel ULg

E-print/Working paper (2015)

In this study, different preprocessing techniques have been applied in order to test if the accuracy of Bubble Image Velocimetry (BIV) calculations in self-aerated flows can be improved. For this purpose ... [more ▼]

In this study, different preprocessing techniques have been applied in order to test if the accuracy of Bubble Image Velocimetry (BIV) calculations in self-aerated flows can be improved. For this purpose, high-speed movies with a resolution of 1920 × 1200 px and a frame rate of 730 Hz are captured on a stepped spillway model with a Phantom M120 camera supplied by LaVision. BIV results are obtained by application of the open-source Matlab® toolbox PIVlab and compared to intrusive data from a double-tip conductivity probe. Averaging velocity fields from 249 frame pairs help to obtain robust results. Therefore, BIV is carried out in a loop with preceding variation of image processing techniques. Results show some potential improvement for the same cross correlation algorithm and post-processing options. However, BIV results tend to underestimate flow velocities when compared to the conductivity probe data. [less ▲]

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See detailImage processing of 2D resistivity data for imaging faults
Nguyen, Frédéric ULg; Garambois, Stephane; Jongmans, Denis et al

in Journal of Applied Geophysics (2005), 57(4), 260-277

A methodology to locate automatically limits or boundaries between different geological bodies in 2D electrical tomography is proposed, using a crest line extraction process in gradient images, This ... [more ▼]

A methodology to locate automatically limits or boundaries between different geological bodies in 2D electrical tomography is proposed, using a crest line extraction process in gradient images, This method is applied on several synthetic models and on field data set acquired on three experimental sites during the European project PALEOSIS where trenches were dug. The results presented in this work are valid for electrical tomographies data collected with a Wenner-alpha array and computed with an 1(1) norm (blocky inversion) as optimization method, For the synthetic cases. three geometric contexts are modelled: a vertical and a dipping fault juxtaposing two different geological formations and a step-like structure. A superficial layer can cover each geological structure. In these three situations, the method locates the synthetic faults and layer boundaries, and determines fault displacement but with several limitations. The estimated fault positions correlate exactly with the synthetic ones if a conductive (or no superficial) layer overlies the studied structure. When a resistive layer with a thickness of 6 in covers the model, faults are positioned with a maximum error of 1 m. Moreover, when a resistive and/or a thick top layer is present, the resolution significantly decreases for the fault displacement estimation (error up to 150%). The tests with the synthetic models for surveys using the Wenner-alpha array indicate that the proposed methodology is best suited to vertical and horizontal contacts. Application of the methodology to real data sets shows that a lateral resistivity contrast of 1:5 1:10 leads to exact faults location. A fault contact with a resistivity contrast of 1:0.75 and overlaid by a resistive layer with a thickness or 1 m gives an error location ranging from 1 to 3 m. Moreover, no result is obtained for a contact with very low contrasts (similar to 1:0.85) overlaid by a resistive soil. The method shows poor results when vertical gradients are greater than horizontal ones. This kind of image processing technique should be systematically used for improving the objectiveness of tomography interpretation when looking for limits between geological objects. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailImage quality and high contrast improvements on VLT/NACO
Girard, J. H. V.; O'Neal, J.; Mawet, D. et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2012)

NACO is the famous and versatile diffraction limited NIR imager and spectrograph at the VLT with which ESO celebrated 10 years of Adaptive Optics. Since two years a substantial effort has been put in ... [more ▼]

NACO is the famous and versatile diffraction limited NIR imager and spectrograph at the VLT with which ESO celebrated 10 years of Adaptive Optics. Since two years a substantial effort has been put in understanding and fixing issues that directly affect the image quality and the high contrast performances of the instrument. Experiments to compensate the non-common-path aberrations and recover the highest possible Strehl ratios have been carried out successfully and a plan is hereafter described to perform such measurements regularly. The drift associated to pupil tracking since 2007 was fixed in october 2011. NACO is therefore even more suited for high contrast imaging and can be used with coronagraphic masks in the image plane. Some contrast measurements are shown and discussed. The work accomplished on NACO will serve as reference for the next generation instruments on the VLT, especially the ones working at the diffraction limit and making use of angular differential imaging (i.e. SPHERE, VISIR, and possibly ERIS). [less ▲]

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See detailImage Quality evaluation for 124I in the microPET Focus 120 scanner using the NEMA NU4-2008 phantom
Bahri, Mohamed Ali ULg; Warnock, Geoffrey ULg; Taleb, Dounia ULg et al

Conference (2011, January 17)

Physical properties of iodine-124 such as its high positron energy, corresponding large positron range in tissue and the fraction of the single γ-photons emitted may have detrimental effects on the PET ... [more ▼]

Physical properties of iodine-124 such as its high positron energy, corresponding large positron range in tissue and the fraction of the single γ-photons emitted may have detrimental effects on the PET image quality. The purpose of this work was to evaluate the image quality for iodine-124 in the small animal microPET Focus 120 scanner using the NEMA NU4-2008 image quality phantom. Although the 2 ns timing window gives higher recovery coefficients and slightly lower spill-over ratios and combined with the 350-590 keV energy window gives the lowest spill-over ratio, the combination of the 350-650 keV and 6 ns windows seems to be the best compromise to obtain images with high contrast and low noise content. [less ▲]

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See detailImage quality in Coronary CT Angiography: Challenges and technical solutions.
Ghekiere, Olivier; Salgado, Rodrigo; Buls, Nico et al

in British Journal of Radiology (2017)

Multidetector CT angiography has become a widely accepted examination for non-invasive evaluation of the heart and coronary arteries. Despite its ongoing success and worldwide clinical implementation, it ... [more ▼]

Multidetector CT angiography has become a widely accepted examination for non-invasive evaluation of the heart and coronary arteries. Despite its ongoing success and worldwide clinical implementation, it remains an often-challenging procedure in which image quality, and hence diagnostic value, is determined by both technical and patient-related factors. Thorough knowledge of these factors is important to obtain high quality examinations. In this review, we discuss several key elements that may adversely affect coronary CT angiography image quality as well as potential measures that can be taken to mitigate their impact. In addition, several recent vendor-specific advances and future directions to improve image quality are discussed. [less ▲]

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See detailImage Quality, Accuracy of Attenuation and Scatter Corrections of the microPET Focus 120 Using the NEMA NU4-2008 Phantom
Bahri, Mohamed Ali ULg; Plenevaux, Alain ULg; Seret, Alain ULg

Poster (2008, October)

This work aimed at evaluating the image quality and the accuracy of attenuation and scatter corrections methodologies provided with the microPET Focus 120 scanner. The protocol used here is described in ... [more ▼]

This work aimed at evaluating the image quality and the accuracy of attenuation and scatter corrections methodologies provided with the microPET Focus 120 scanner. The protocol used here is described in the forthcoming NEMA NU4-2008 document. This study included 1 h transmission experiments, with two sources (68Ge and 57Co, both one half-live old), in coincidence mode (Ge) with and without windowing, and singles mode (Ge and Co). Transmission data with Co were also collected for shorter acquisition times (515/1030/2060 s). Transmission with scatter correction, and emission with attenuation with or without scatter correction, slices were reconstructed using 2D-FBP (ramp filter). The uniformity, the recovery coefficients (RC) and the accuracy of corrections were evaluated as described in the NEMA document. We also determined the attenuation coefficient (AC) for water using the methodology applied to measure the mean pixel value for the emission slices of the uniform part of the phantom. The Co single mode measurements provided a mean AC for water closer to the theoretical value than the Ge measurements either in single or in coincidence mode even for the shortest acquisition time. Moreover, the lowest coefficients of variation per pixel of the uniform slices were measured for attenuation corrected data based on Co measurements. Also, spill-over ratio for non-emitting air and water compartments reflected a higher capability of this attenuation correction method for scatter correction. The RC measured on emission image corrected only for attenuation did not show any significant difference linked to the transmission measured methods. However, higher RC values were noted for Ge coincidence with windowing when emission data were corrected for both attenuation and scatter. Hence, Co singles transmission seems to be the most suitable method for attenuation correction on the microPET Focus 120 scanner. [less ▲]

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See detailImage Reconstruction from Strip Integrals in Computer-aided X-ray Tomography
Verly, Jacques ULg; Bracewell, Ronald N.

Conference (1979, August)

Detailed reference viewed: 25 (3 ULg)
See detailImage reconstruction in X-ray tomography
Toye, Dominique ULg; Fransolet, Emmanuelle; Léonard, Angélique ULg et al

Scientific conference (2004, August)

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See detailImage sans Texte. Le vase de Leukôn
Morard, Thomas ULg

Scientific conference (2015, November 09)

Detailed reference viewed: 19 (4 ULg)
See detailIMAGE SATELLITAIRE - Planche IX.1 du Deuxième Atlas de Belgique
Cornélis, Bernard; Binard, Marc ULg

Cartographic material (1996)

Detailed reference viewed: 45 (0 ULg)
See detailImage satellitaire de la Belgique – Commentaire de la planche IX-1 (en 4 langues)
Donnay, Jean-Paul ULg; Cornélis, Bernard

in Comité Belge de Géographie (Ed.) Atlas National de Belgique (1996)

Detailed reference viewed: 16 (0 ULg)
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See detailL'image scientifique : de la visualisation à la mathématisation et retour
Dondero, Maria Giulia ULg

in Nouveaux Actes Sémiotiques (2009)

Cet article soumet à investigation les rôles des images dans la production en laboratoire et dans la littérature scientifique de l’astrophysique et de la physique théorique. D’un côté l’image en ... [more ▼]

Cet article soumet à investigation les rôles des images dans la production en laboratoire et dans la littérature scientifique de l’astrophysique et de la physique théorique. D’un côté l’image en astrophysique fonctionne en tant qu’instrument d’enregistrement des données permettant de caractériser un phénomène (régime autographique) : dans ce cas l’image transforme les traces d’un phénomène en un objet (nébuleuse, supernova, etc.), produit d’une négociation, qui sera ensuite accepté, stabilisé et institutionnalisé à l’intérieur de la discipline. De l’autre côté, l’image peut aussi devenir un instrument d’investigation, voire un terrain de travail visant la production d’autres iconographies et ainsi d’autres objets. Ce dernier fonctionnement de l’image relève du régime allographique (voir Nelson Goodman, Les langages de l’art. Pour une théorie des symboles, 1968) : dans ce cas l’image se présente comme un texte d’instructions pour la production d’autres images : elle devient un texte générateur et permet une mathématisation des données. En prenant ensuite en considération les recherches en physique théorique sur les trous noirs, notre article étudie la relation entre équations et visualisation. On étudie plus précisément la première iconographie des trous noirs proposée par l’astrophysicien Jean-Pierre Luminet en 1979. Les travaux de Luminet qu’on analyse dans notre article montrent l’effort de construction d’une iconographie d’un objet théorique ni visible ni photographiable tel les trous noirs, et la nécessité de visualiser les résultats des équations pour faire avancer les hypothèses et la connaissance de ces phénomènes. Enfin, l’image en physique théorique, produite par des équations, montre le pouvoir que la visualisation a de mettre en scène un objet pluriel, voire un certain type de trous noirs, et de devenir ainsi une image modèle mais toujours ultérieurement manipulable (diagramme). [less ▲]

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See detailL’image scientifique : Pratiques de production, visualisation et interpretation
Dondero, Maria Giulia ULg

in Nouveaux Actes Sémiotiques (2008)

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See detailImage scientifique et énonciation du temps
Dondero, Maria Giulia ULg

in Visible (2009), 5

Detailed reference viewed: 53 (3 ULg)
See detailImage(s) de soi, image(s) de l’autre
Lanneau, Catherine ULg

Conference (2010, October 16)

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See detailImage, imagination et mathématique chez Descartes et Leibniz
Bouquiaux, Laurence ULg

in Visible (2012)

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See detailImage-based Finite Element Mesh Generation for Microstructures
D'Otreppe, Vinciane ULg; Mengoni, Marlène ULg; Boman, Romain ULg et al

Conference (2011, November 14)

Detailed reference viewed: 110 (43 ULg)
See detailIMAGE-FUV multispectral observation of theta auroras.
Hubert, Benoît ULg; Gérard, Jean-Claude ULg; Mende, S. B. et al

Conference (2002, May 01)

The theta aurora is an auroral structure presenting a sun-aligned transpolar arc. Five different dynamic evolution of the transpolar arcs are known, some of them being symmetrical to each other, leaving ... [more ▼]

The theta aurora is an auroral structure presenting a sun-aligned transpolar arc. Five different dynamic evolution of the transpolar arcs are known, some of them being symmetrical to each other, leaving three basically different types of transpolar auroral features. The theta aurora was previously studied with in-situ particles detectors onboard polar orbiting satellites and by ultraviolet imagers. Previous imaging works focused on the electron aurora. We use the FUV imagers onboard the IMAGE spacecraft to study separately the proton and electron contributions to the transpolar arcs at the global scale. The imagers of the IMAGE-FUV experiment remotely sense the electron aurora with the WIC and SI13 imagers observing respectively the N[SUB]2[/SUB]-LBH and OI-135.6 nm emission, while the SI12 spectrographic imager measures the Doppler-shifted Lyman-ë± emission which is solely due to the auroral proton precipitation. The three different types of transpolar aurora will be analyzed using the IMAGE-FUV imagers. In particular, the relative contribution of proton and electron to the excitation of the theta aurora will be presented. [less ▲]

Detailed reference viewed: 23 (1 ULg)