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See detailX ray in RDS with HFOV and surfactant: what has changed ?
Battisti, Oreste ULg; Rausin, L.; Khamis, J. et al

Conference (1997, October 24)

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See detailAn X Ray of Money Market Fund Risks
Bodson, Laurent ULg; Debatty, Philippe; Masquelier, F.

in Treasury Management International Magazine (2008)

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See detailX-FEM explicit dynamics for constant strain elements to alleviate mesh constraints on internal or external boundaries
Rozycki, P.; Moes, N.; Béchet, Eric ULg et al

in Computer Methods in Applied Mechanics & Engineering (2008), 197(5), 349-363

This paper deals with the use of the extended Finite Element Method (X-FEM) for rapid dynamic problems. To solve the equations of motion, a common technique is the explicit direct integration with a ... [more ▼]

This paper deals with the use of the extended Finite Element Method (X-FEM) for rapid dynamic problems. To solve the equations of motion, a common technique is the explicit direct integration with a Newmark scheme. Since this temporal scheme is only conditionally stable, the critical time step must be determined. It is generally induced by mesh constraints. The idea of the paper is to weaken constraints on mesh generation algorithms so that the critical time step is as large as possible. Using the X-FEM one allows a non-conformity between mesh and discontinuities such as cracks, holes or interfaces. In a first part, we present a summary about direct integration schemes and about the eXtended Finite Element Method. Then, we focus on the theoretical description of a ID X-FEM finite element and its generalization to 2D and 3D finite elements. Then, dynamic numerical simulations are shown. They concern structures under impact with holes or external boundaries not exactly matched by the mesh. Comparisons are made with numerical results coming from the ABAQUS software. It shows that developments are satisfactory. We conclude with some outlooks concerning this work. (c) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailX-ray analysis of the NMC-A beta-lactamase at 1.64-A resolution, a class A carbapenemase with broad substrate specificity
Swaren, Peter; Maveyraud, Laurent; Raquet, Xavier et al

in Journal of Biological Chemistry (1998), 273(41), 26714-26721

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See detailX-ray Computed Tomography for Non-Destructive Testing
Wevers, Martine; Kerckhofs, Greet ULg; Pyka, Gregory et al

in Proceedings iCT 2012 (2012)

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See detailX-ray Computed Tomography in the Presence of Arbitrary Focal Spot Intensity Distributions
Verly, Jacques ULg

in Medical Physics (1980), 7(1), 27-34

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See detailX-ray CT study of the influence of liquid viscosity on fluid phase distribution in modular catalytic packings
Aferka, Saïd ULg; Viva, Aurora; Toye, Dominique ULg et al

in AIDIC Conference series (2010), 10

In the frame of the present study, the influence of liquid viscosity on liquid holdup distribution in a packed column equipped with the modular catalytic packing Katapak-SP 11 is measured. Water and an ... [more ▼]

In the frame of the present study, the influence of liquid viscosity on liquid holdup distribution in a packed column equipped with the modular catalytic packing Katapak-SP 11 is measured. Water and an aqueous solution of glycerine, the viscosity of which equals 10 cP, are used as feed liquids. The estimation of liquid holdup is of great interest due to its strong influence on pressure drop, on solid wetting and on heat and mass transfer coefficients. The experimental technique used is high energy X-ray tomography, which is a unique technique to visualize the local liquid distribution inside the complex structure of packings and to quantify the liquid holdup at different scales. [less ▲]

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See detailX-ray CT study of the influence of liquid viscosity on fluid phase distribution in modular catalytic packings
Aferka, Saïd ULg; Viva, Aurora; Brunazzi, Elisabetta et al

in Chemical Engineering Transactions (2011), 24

In the frame of the present study, the influence of liquid viscosity on liquid holdup distribution in a packed column equipped with the modular catalytic packing Katapak-SP 11 is measured. Water and an ... [more ▼]

In the frame of the present study, the influence of liquid viscosity on liquid holdup distribution in a packed column equipped with the modular catalytic packing Katapak-SP 11 is measured. Water and an aqueous solution of glycerine, the viscosity of which equals 10 cP, are used as feed liquids. The estimation of liquid holdup is of great interest due to its strong influence on pressure drop, on solid wetting and on heat and mass transfer coefficients. The experimental technique used is high energy X-ray tomography, which is a unique technique to visualize the local liquid distribution inside the complex structure of packings and to quantify the liquid holdup at different scales. [less ▲]

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See detailX-ray Emission from Early-Type Stars: New Results and New Challenges
Rauw, Grégor ULg

in The X-ray Universe 2005 (2006, January 01)

Not Available

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See detailX-ray Emission from the Double-binary OB-star System QZ Car (HD 93206)
Parkin, E. R.; Broos, P. S.; Townsley, L. K. et al

in Astrophysical Journal. Supplement Series (2011), 194

X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The respective orbits of systems A (O9 ... [more ▼]

X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The respective orbits of systems A (O9.7 I+b2 v, P [SUB]A[/SUB] = 21 days) and B (O8 III+o9 v, P [SUB]B[/SUB] = 6 days) are reasonably well sampled by the observations, allowing the origin of the X-ray emission to be examined in detail. The X-ray spectra can be well fitted by an attenuated three-temperature thermal plasma model, characterized by cool, moderate, and hot plasma components at kT ~= 0.2, 0.7, and 2 keV, respectively, and a circumstellar absorption of sime0.2 × 10[SUP]22[/SUP] cm[SUP]-2[/SUP]. Although the hot plasma component could be indicating the presence of wind-wind collision shocks in the system, the model fluxes calculated from spectral fits, with an average value of sime7 × 10[SUP]-13[/SUP] erg s[SUP]-1[/SUP] cm[SUP]-2[/SUP], do not show a clear correlation with the orbits of the two constituent binaries. A semi-analytical model of QZ Car reveals that a stable momentum balance may not be established in either system A or B. Yet, despite this, system B is expected to produce an observed X-ray flux well in excess of the observations. If one considers the wind of the O8 III star to be disrupted by mass transfer, the model and observations are in far better agreement, which lends support to the previous suggestion of mass transfer in the O8 III + o9 v binary. We conclude that the X-ray emission from QZ Car can be reasonably well accounted for by a combination of contributions mainly from the single stars and the mutual wind-wind collision between systems A and B. [less ▲]

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See detailX-ray emission of interacting wind binaries in Cyg OB2
Nazé, Yaël ULg; Cazorla, Constantin ULg; Rauw, Grégor ULg

in EAS Publications Series (2013, February 01)

Cyg OB2 #5, #8A, and #9 are binary or multiple massive stars in the Cyg OB2 association displaying several peculiarities, such as bright X-ray emission and non-thermal radio emission. Our X-ray monitoring ... [more ▼]

Cyg OB2 #5, #8A, and #9 are binary or multiple massive stars in the Cyg OB2 association displaying several peculiarities, such as bright X-ray emission and non-thermal radio emission. Our X-ray monitoring of these stars reveals the details of their behaviours at high energies, which can be directly linked to wind-wind collisions (WWCs). In addition, the X-ray emission of Cyg OB2 #12, an evolved massive star, shows a long-term decrease, which could hint at the presence of a companion (with associated colliding winds) or indicate the return to quiescence of the star following a recent eruption. [less ▲]

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See detailX-ray emission of interacting wind binaries in Cyg OB2
Nazé, Yaël ULg; Cazorla, Constantin ULg; Rauw, Grégor ULg

Poster (2013, September)

Cyg OB2 #5, #8A, and #9 are binary or multiple massive stars in the Cyg OB2 association displaying several peculiarities, such as bright X-ray emission and non-thermal radio emission. Our X-ray monitoring ... [more ▼]

Cyg OB2 #5, #8A, and #9 are binary or multiple massive stars in the Cyg OB2 association displaying several peculiarities, such as bright X-ray emission and non-thermal radio emission. Our X-ray monitoring of these stars reveals the details of their behaviours at high energies, which can be directly linked to wind-wind collisions (WWCs). In addition, the X-ray emission of Cyg OB2 #12, an evolved massive star, shows a long-term decrease, which could hint at the presence of a companion (with associated colliding winds) or indicate the return to quiescence of the system following a recent eruption. [less ▲]

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See detailThe X-ray emission of the colliding wind binary V444 Cyg
Fauchez, Thomas; De Becker, Michaël ULg; Nazé, Yaël ULg

in Bulletin de la Societe Royale des Sciences de Liege (2011), 80

This paper presents the analysis of six XMM-Newton observations of the colliding wind system V444 Cyg. Unlike what one might have expected at first, it appears that the O star wind most probably dominates ... [more ▼]

This paper presents the analysis of six XMM-Newton observations of the colliding wind system V444 Cyg. Unlike what one might have expected at first, it appears that the O star wind most probably dominates the WN wind: the bow shock is wide open, with the hard X-ray emission arising close to the WN star. An important radiative braking could partly explain this situation but revising the wind parameters may also prove necessary. Furthermore, we have probably observed for the first time an occultation of the colliding wind zone by the binary components. [less ▲]

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See detailThe X-ray emission of the WR+O binary WR 79
Gosset, Eric ULg; Sana, Hugues; Rauw, Grégor ULg et al

in Bulletin de la Societe Royale des Sciences de Liege (2011), 80

In the framework of our multiwavelength study of the open cluster NGC 6231, we observed the colliding-wind WR+O binary WR 79 at six different epochs with the XMM-Newton observatory. These pointings offer ... [more ▼]

In the framework of our multiwavelength study of the open cluster NGC 6231, we observed the colliding-wind WR+O binary WR 79 at six different epochs with the XMM-Newton observatory. These pointings offer the possibility to study the X-ray spectrum of WR 79 and its possible variability. Our results are briefly discussed and compared with the X-ray characteristics of other similar objects. [less ▲]

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See detailThe X-ray emission spectra of multicharged xenon ions in a gas puff laser-produced plasma
Yu Skobelev, I.; Dyakin, V. M.; Ya Faenov, A. et al

in Journal of Physics : B Atomic Molecular & Optical Physics (1999), 32

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See detailX-Ray Emissions from Jupiter
Gladstone, G.; Waite, J.; Grodent, Denis ULg et al

Conference (2001, May 29)

X-ray emissions from Jupiter have been observed for over 20~years. Jovian x-ray emissions are associated with the high-latitude aurora and with solar fluorescence and/or an energetic particle source at ... [more ▼]

X-ray emissions from Jupiter have been observed for over 20~years. Jovian x-ray emissions are associated with the high-latitude aurora and with solar fluorescence and/or an energetic particle source at low-latitudes as identified by past Einstein and ROSAT observations. Enhanced auroral x-rays were also observed to be associated with the impact of Comet Shoemaker-Levy~9. The high-latitude x-ray emissions are best explained by energetic sulfur and oxygen ion precipitation from the Jovian magnetosphere, a suggestion that has been confirmed by recent Chandra ACIS observations. Exciting new information about Jovian x-ray emissions has been made possible with Chandra's High Resolution Camera. We report here for the first time the detection of a forty minute oscillation associated with the Jovian x-ray aurora. With the help of ultraviolet auroral observations from Hubble Space Telescope, we pinpoint the auroral mapping of the x-rays and provide new information on the x-ray source mechanism. [less ▲]

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See detailAn X-ray investigation of the NGC 346 field in the Small Magellanic Cloud - I. The luminous blue variable HD 5980 and the NGC 346 cluster
Nazé, Yaël ULg; Hartwell, J. M.; Stevens, I. R. et al

in Astrophysical Journal (2002), 580(Part 1), 225-234

We present results from a Chandra observation of the NGC 346 cluster. This cluster contains numerous massive stars and is responsible for the ionization of N66, the most luminous H II region and the ... [more ▼]

We present results from a Chandra observation of the NGC 346 cluster. This cluster contains numerous massive stars and is responsible for the ionization of N66, the most luminous H II region and the largest star formation region in the SMC. In this first paper we will focus on the characteristics of the main objects of the field. The NGC 346 cluster itself shows only relatively faint X-ray emission (with L-X(unabs) similar to 1.5x10(34) ergs s(-1)), tightly correlated with the core of the cluster. In the field also lies HD 5980, a luminous blue variable star in a binary (or possibly a triple) system that is detected for the first time at X-ray energies. The star is X-ray bright, with an unabsorbed luminosity of L-X(unabs) similar to 1.7x10(34) ergs s(-1), but needs to be monitored further to investigate its X-ray variability over a complete 19 day orbital cycle. The high X-ray luminosity may be associated either with colliding winds in the binary system or with the 1994 eruption. HD 5980 is surrounded by a region of diffuse X-ray emission, which is a supernova remnant. While it may be only a chance alignment with HD 5980, such a spatial coincidence may indicate that the remnant is indeed related to this peculiar massive star. [less ▲]

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See detailAn X-ray investigation of the NGC 346 field in the Small Magellanic Cloud. II. The field population
Nazé, Yaël ULg; Hartwell, J. M.; Stevens, I. R. et al

in Astrophysical Journal (2003), 586(2, Part 1), 983-995

We present results from a Chandra observation of the NGC 346 cluster, which is the ionizing source of N66, the most luminous H II region and the largest star formation region in the SMC. In the first part ... [more ▼]

We present results from a Chandra observation of the NGC 346 cluster, which is the ionizing source of N66, the most luminous H II region and the largest star formation region in the SMC. In the first part of this investigation, we have analyzed the X-ray properties of the cluster itself and the remarkable star HD 5980, but the field contains additional objects of interest. In total, 75 X-ray point sources were detected in the Chandra observation: this is 5 times the number of sources detected by previous X-ray surveys. We investigate here their characteristics in detail. Because of high foreground absorption, the sources possess rather high hardness ratios. Their cumulative luminosity function appears generally steeper than that for the rest of the SMC at higher luminosities. Their absorption columns suggest that most of the sources belong to NGC 346. Using Digitized Sky Survey data and new UBVRI imaging with the ESO 2.2 m telescope, we also discovered possible counterparts for 32 of these X-ray sources and estimated a B spectral type for a large number of these counterparts. This tends to suggest that most of the X-ray sources in the field are in fact X-ray binaries. Finally, some objects show X-ray and/or optical variability, with a need for further monitoring. [less ▲]

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