References of "Remy, M"
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See detailDevelopment of a Mesoscopic Cell Modeling the Damage Process in Steel at Elevated Temperature
Castagne, Sylvie; Remy, M.; Habraken, Anne ULg

in Key Engineering Materials [=KEM] (2003), 233-236

An on going project whose goal is the development and identification of a mathematical model of steel at elevated temperature using a mesoscopic approach is presented. The research aims to study the ... [more ▼]

An on going project whose goal is the development and identification of a mathematical model of steel at elevated temperature using a mesoscopic approach is presented. The research aims to study the damage process at elevated temperature using information from the macroscopic and mesoscopic scales. As a final application our results will be used to study the industrial process of continuous casting of low carbon steel. [less ▲]

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See detailProgress in microscopic modeling of damage in steel at high temperature
Remy, M.; Castagne, Sylvie; Habraken, Anne ULg

in International Journal of Forming Processes (2002), 5(N°2-3-4/2002), 445-455

With the goal to study crack propagation in continuous casting, this paper presents an on going project to develop and identify a mathematical finite element model of damage in steel at high temperature ... [more ▼]

With the goal to study crack propagation in continuous casting, this paper presents an on going project to develop and identify a mathematical finite element model of damage in steel at high temperature. A representative microscopic cell of the material is presented and adapted to available chemical information, precipitation state and micro-structures observed using metallographic as weel as imaging methods (optical microscopy, SEM, orientation imaging microscopy). Compression tests of cylindrical samples after a thermal treatment have been performed to identify the parameters of an elasto-visco-plastique law of Norton-Hoff type. Hot damage tests in tensile and compression states help to provide information on crack appearance. [less ▲]

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See detailIdentification d'une loi thermo-élasto-viscoplastique en vue de la modélisation du laminage à chaud du cuivre
Moureaux, P.; Moto Mpong, S.; Remy, M. et al

in Journal de Physique IV (2002), 102

la mise au point d'un modèle de simulation de la dernière passe du laminage à chaud du cuivre ne présente à priori pas de problème du point de vue numérique pour un code d'éléments finis non linéaire. La ... [more ▼]

la mise au point d'un modèle de simulation de la dernière passe du laminage à chaud du cuivre ne présente à priori pas de problème du point de vue numérique pour un code d'éléments finis non linéaire. La collecte d'informations précises tant sur le procédé industriel que sur le comportement du matériau est par contre une opération non triviale. Cet article présente les diverses méthodes expérimentales mises en œuvre pour caractériser le matériau: essais de compression à chaud, mesures d'analyse thermique différentielle, essais de dilatométrie et de diffusivité. Les méthodes permettant d'identifier les paramètres de la loi élasto-visco-plastique de type Norton-Hoff à partir des essais sont présentées et une analyse bibliographique investigue le problème de la détermination du module de Young à haute température. Tant les hypothèses supplémentaires relatives au procédé et nécessaires au modèle que les résultats finaux sont résumés. [less ▲]

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See detailThe relevance of HST observations for studies of quasars, gravitational lenses and intervening gas clouds "
Surdej, Jean ULg; Claeskens, Jean-François ULg; Jean, C. et al

in Space Sciences, Vol. II, Part 1: Space Scientific Research in Belgium (2001)

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See detailQSO mass constraints from gravitational lensing studies of quasar pairs. The cases of Q1548+114 A & B and Q1148+0055 A & B
Claeskens, Jean-François ULg; Lee, D.-W.; Remy, M. et al

in Astronomy and Astrophysics (2000), 356

New constraints on the mass of quasars are derived from gravitational lensing studies of the QSO pairs Q1548+114 A & B and Q1148+0055 A & B, for which new ground-based and Hubble Space Telescope (HST ... [more ▼]

New constraints on the mass of quasars are derived from gravitational lensing studies of the QSO pairs Q1548+114 A & B and Q1148+0055 A & B, for which new ground-based and Hubble Space Telescope (HST) direct imagery have been obtained. In the case of Q1548+114 A & B, QSO A has been resolved into its host galaxy and a close companion. The non-detection with HST of a secondary lensed image of the background QSO in the close vicinity of the foreground one and the modeling of the host of QSO A, of the companion and of field galaxies with Singular Isothermal Spheres (SIS) yield a robust upper limit on the central compact mass of 4.5 10[SUP]11[/SUP] M[SUB]sun[/SUB]. On the other hand, the combined mass of Q1148+0055 B plus host must be smaller than 6.5 10[SUP]11[/SUP] M[SUB]sun[/SUB] since no secondary lensed image has been detected with HST. Photometry and relative astrometry of all the detected objects are reported. Based on data collected with the Hubble Space Telescope and at the European Southern Observatory, La Silla, Chile [less ▲]

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See detailWFPC2 PSF Subtractions
Baggett, S.; Remy, M.; Surdej, Jean ULg et al

in Bulletin of the American Astronomical Society (1998, December 01)

Subtraction of scaled PSFs from direct CCD images of quasars (or stars) offers not only the possibility of detecting the presence of host or foreground galaxies (or companions like brown dwarfs or planets ... [more ▼]

Subtraction of scaled PSFs from direct CCD images of quasars (or stars) offers not only the possibility of detecting the presence of host or foreground galaxies (or companions like brown dwarfs or planets) but also provides a means of deriving accurate photometry of the primary objects. A series of PSF subtraction tests have been performed, using observed PSFs from the WFPC2 PSF Library as well as TinyTim PSFs; preliminary results indicate that appropriate synthetic TinyTim PSFs perform as well as observed PSFs. Specifically, using an optimally selected observed PSF, near the target on the chip ( < 10arcsec ), close in focus (within 1-2 microns), similar in spectral type, and with good S/N, yielded single photometric values with an RMS of ~ 0.01-0.02 mag. Using a carefully constructed synthetic PSF, close in focus and jitter to the target image, and as close as possible to the center of the target, resulted in photometric results with an RMS similar to that achieved with the observed PSF (0.01-0.02 mag). [less ▲]

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See detailPolarization properties of a sample of broad absorption line and gravitationally lensed quasars
Hutsemekers, Damien ULg; Lamy, H.; Remy, M.

in Astronomy and Astrophysics (1998), 340

New broad-band linear polarization measurements have been obtained for a sample of 42 optically selected QSOs including 29 broad absorption line (BAL) QSOs. The polarization properties of different sub ... [more ▼]

New broad-band linear polarization measurements have been obtained for a sample of 42 optically selected QSOs including 29 broad absorption line (BAL) QSOs. The polarization properties of different sub-classes have been compared, and possible correlations with various spectral indices searched for. The main results of our study are: (1) Nearly all highly polarized QSOs of our sample belong to the sub-class of BAL QSOs with low-ionization absorption features (LIBAL QSOs). (2) The range of polarization is significantly larger for LIBAL QSOs than for high-ionization (HI) BAL QSOs and non-BAL QSOs. (3) There is some indication that HIBAL QSOs as a class may be more polarized than non-BAL QSOs and therefore intermediate between LIBAL and non-BAL QSOs, but the statistics are not compelling from the sample surveyed thus far. (4) For LIBAL QSOs, the continuum polarization appears significantly correlated with the line profile detachment index, in the sense that LIBAL QSOs with P Cygni-type profiles are more polarized. No correlation was found with the strength of the low- or the high-ionization absorption features, nor with the strength or the width of the emission lines. These results are consistent with a scenario in which LIBAL QSOs constitute a different class of radio-quiet QSOs with more absorbing material and more dust. Higher maximum polarization can therefore be reached, while the actually measured polarization depends on the geometry and orientation of the system as do the line profiles. The observed correlation is interpreted within the framework of recent ``wind-from-disk'' models. Tables~2 and 3 are also available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html}\fnmsep\thanks{Based on observations collected at the European Southern Observatory (ESO, La Silla) [less ▲]

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See detailThree photometric methods tested on ground-based data of Q 2237+0305
Burud, I.; Stabell, R.; Magain, Pierre ULg et al

in Astronomy and Astrophysics (1998), 339

The Einstein Cross, Q 2237+0305, has been photometrically observed in four bands on two successive nights at NOT (La Palma, Spain) in October 1995. Three independent algorithms have been used to analyse ... [more ▼]

The Einstein Cross, Q 2237+0305, has been photometrically observed in four bands on two successive nights at NOT (La Palma, Spain) in October 1995. Three independent algorithms have been used to analyse the data: an automatic image decomposition technique, a CLEAN algorithm and the new MCS deconvolution code. The photometric and astrometric results obtained with the three methods are presented. No photometric variations were found in the four quasar images. Comparison of the photometry from the three techniques shows that both systematic and random errors affect each method. When the seeing is worse than 1farcs0 , the errors from the automatic image decomposition technique and the Clean algorithm tend to be large (0.04-0.1 magnitudes) while the deconvolution code still gives accurate results (1sigma error below 0.04) even for frames with seeing as bad as 1farcs7 . Reddening is observed in the quasar images and is found to be compatible with either extinction from the lensing galaxy or colour dependent microlensing. The photometric accuracy depends on the light distribution used to model the lensing galaxy. In particular, using a numerical galaxy model, as done with the MCS algorithm, makes the method less seeing dependent. Another advantage of using a numerical model is that eventual non-homogeneous structures in the galaxy can be modeled. Finally, we propose an observational strategy for a future photometric monitoring of the Einstein Cross. Based on observations obtained at NOT, La Palma. [less ▲]

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See detailSpatial distribution of the Ly-alpha forest
Petitjean, P.; Surdej, Jean ULg; Remy, M. et al

in D'Odorico, S.; Fontana, A.; Giallongo, E. (Eds.) The Young Universe: Galaxy Formation and Evolution at Intermediate and High Redshift (1998)

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See detailDetection of the lensing galaxy for the double QSO HE 1104-1805
Remy, M.; Claeskens, Jean-François ULg; Surdej, Jean ULg et al

in New Astronomy (1998), 3

High angular resolution ground-based direct imaging (V, R, I_c) of the double QSO HE 1104-1805 has been obtained with the NOT and NTT telescopes. Analysis of these data led to the first detection of the ... [more ▼]

High angular resolution ground-based direct imaging (V, R, I_c) of the double QSO HE 1104-1805 has been obtained with the NOT and NTT telescopes. Analysis of these data led to the first detection of the lensing galaxy. Direct imaging of HE 1104-1805 has subsequently been carried out with the Planetary Camera (WFPC2) through the F555W (nearly Johnson V) and F814W (nearly Kron-Cousins I_c) filters onboard HST. These images confirm the presence of the deflector between the two lensed quasar components (A & B). Direct imaging of this system in the near infrared (IR) at 2.2 mu-m (K'), with IRAC-2b at the Cassegrain focus of the ESO/MPI 2.2 m telescope, indicates that the additional component is indeed a very red extended object with magnitude K ~= 16.5. We present deconvolutions of the HST and IR images using the 2-channel PLUCY method. From the HST observations, we also report very accurate relative positions and brightnesses of the QSO components. By comparison between the ground-based and the HST observations, from February-March 1994 to November 1995, we possibly detect the fading of component A by ~ 0.3 magnitudes in the optical and a corresponding fading of B by about half this value. The observed monotonic decrease of the magnitude difference between B and A as a function of wavelength is consistent with a partial amplification of the A component by microlensing. Evolutionary models for galaxies show that, in order to produce the observed colour indices V - I_c > 2 and 4 < I_c - K < 4.5, the galaxy is likely to be of elliptical type with a redshift 0.95 < z < 1.4. This range is consistent with the redshift z=1.32 measured from the absorption lines of metallic species in the spectra of the quasar components. However, other values for the redshift of the lens inside this range cannot be excluded. This galaxy would presently be among the most distant known gravitational lenses. Several theoretical models are found to fit the observations. The simplest one is a singular isothermal sphere (SIS) lens immersed in an external shear with gamma=0.123. The derived mass-to-light ratio (11 h_50 M_Sun/L_Sun) for the galaxy is large but does not imply an excess of dark matter with respect to other well known lensing galaxies. [less ▲]

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See detailESO & NOT photometric monitoring of the Cloverleaf quasar
Ostensen, R.; Remy, M.; Lindblad, P. O. et al

in Astronomy and Astrophysics. Supplement Series (1997), 126

The Cloverleaf quasar, H1413+117, has been photometrically monitored at ESO (La Silla, Chile) and with the NOT (La Palma, Spain) during the period 1987--1994. All good quality CCD frames have been ... [more ▼]

The Cloverleaf quasar, H1413+117, has been photometrically monitored at ESO (La Silla, Chile) and with the NOT (La Palma, Spain) during the period 1987--1994. All good quality CCD frames have been successfully analysed using two independent methods (i.e. an automatic image decomposition technique and an interactive CLEAN algorithm). The photometric results from the two methods are found to be very similar, and they show that the four lensed QSO images vary significantly in brightness (by up to 0.45 mag), nearly in parallel. The lightcurve of the $D$ component presents some slight departures from the general trend which are very likely caused by micro-lensing effects. Upper limits, at the 99% confidence level, of 150 days on the absolute value for the time delays between the photometric lightcurves of this quadruply imaged variable QSO, are derived. This is unfortunately too large to constrain the lens model but there is little doubt that a better sampling of the lightcurves should allow to accurately derive these time delays. Pending a direct detection of the lensing galaxy (position and redshift), this system thus constitutes another good candidate for a direct and independent determination of the Hubble parameter. Based on observations collected at the European Southern Observatory (La Silla, Chile) and with the Nordic Optical Telescope (La Palma, Spain). Table 1. Logbook for the ESO and NOT observations together with photometric results for the Cloverleaf quasar. This long table can be accessed on the WWW at the URL address: http://vela.astro.ulg.ac.be/grav_lens/glp_homepage.html} [less ▲]

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See detailHST confirmation of the lensed quasar J03.13.
Surdej, Jean ULg; Claeskens, Jean-François ULg; Remy, M. et al

in Astronomy and Astrophysics (1997), 327

In order to definitely prove the claim by Claeskens et al. (1996A&A...305L...9C) that J03.13 is a doubly imaged quasar, WFPC2 direct imaging and FOS spectroscopy of this compact system have been obtained ... [more ▼]

In order to definitely prove the claim by Claeskens et al. (1996A&A...305L...9C) that J03.13 is a doubly imaged quasar, WFPC2 direct imaging and FOS spectroscopy of this compact system have been obtained with HST. These textbook case observations clearly show that J03.13 consists of two point-like images separated by 0.849"+/-0.001" with a magnitude difference of 2.14+/-0.03 in V and I. We see no trace of a lensing galaxy. From the FOS observations, we find that J03.13 A and B have identical spectra within the measurement uncertainties. The data also show that spectroscopic contamination of B by A is negligible. We do confirm the redshift z=2.545 for J03.13 A and B (emission-lines due to Ly-beta lambda1025 and O VI lambdalambda1031, 1037 are also detected), first derived from an unresolved ground-based spectrum of the two components by Claeskens et al. We also find that the absorption line system at z=2.344 (CIV and Ly-alpha) is present in the spectra of A and B. On the contrary, the absorption line system at z=1.085 (MgII) is only present in the spectrum of J03.13 A. If this latter system is associated with the lens, we may expect that image A consists of two radially merging images with a very small angular separation. From the WFPC2 imagery, we can rule out the presence of a third component fainter than A by up to 5.2mag. with an angular separation >=0.13". [less ▲]

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See detailHST observations of the gravitational lens systems HE 1104-1805 and J03.13
Remy, M.; Claeskens, Jean-François ULg; Surdej, Jean ULg

in Casertano, S. (Ed.) The 1997 HST Calibration Workshop with a New Generation of Instruments (1997, January 01)

High angular resolution Principle Component Image (PC1) images of the gravitational lens systems HE 1104-1805 and J03.13 are presented. Using a method described in Remy et al. (1997a), optimal TinyTim ... [more ▼]

High angular resolution Principle Component Image (PC1) images of the gravitational lens systems HE 1104-1805 and J03.13 are presented. Using a method described in Remy et al. (1997a), optimal TinyTim Point Spread Function (PSFs) are constructed to fit at best the lensed point-like components. The derived photometry of the GL components and the detection of the lens galaxy for HE 1104-1805 are discussed. Textbook case Faint Object Spectrograph (FOS) spectra of J03.13 A and B clearly show that this double QSO is a cosmic mirage. [less ▲]

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See detailWFPC2 photometry from subtraction of TinyTim PSFs
Remy, M.; Surdej, Jean ULg; Baggett, S. et al

in The 1997 HST Calibration Workshop with a New Generation of Instruments, p. 374 (1997, January 01)

Based upon the subtraction of TinyTim Point Spread Function (PSFs) from Principle Component Image (PC1) point-like objects, a method has been developed to determine the optimal values for the telescope ... [more ▼]

Based upon the subtraction of TinyTim Point Spread Function (PSFs) from Principle Component Image (PC1) point-like objects, a method has been developed to determine the optimal values for the telescope jitter and the Z4 relative focus during calibration or science observations. Using these jitter and focus values, an optimal TinyTim PSF, computed over a resampled grid, is then iteratively fitted to the object, yielding an improvement in the PSF centering, more accurate photometric results and a better detection of underlying structures. Preliminary results seem to indicate that appropriate synthetic TinyTim PSFs perform as well as observed PSFs. [less ▲]

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See detailWFPC2 Photometry from Subtraction of Observed PSFs
Surdej, Jean ULg; Baggett, S.; Remy, M. et al

in Casertano, Stefano; Jedrzejewski, Robert; Keyes, Charles D (Eds.) et al The 1997 HST Calibration Workshop with a new generation of instruments (1997, January 01)

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See detailJ03.13 A and B: a new multiply imaged QSO candidate.
Claeskens, Jean-François ULg; Surdej, Jean ULg; Remy, M.

in Astronomy and Astrophysics (1996), 305

Careful analysis of direct R CCD frames obtained for selected Highly Luminous Quasars in March 1993 with the MPI/ESO 2.2m telescope has revealed that the quasar J03.13 consists of at least two point-like ... [more ▼]

Careful analysis of direct R CCD frames obtained for selected Highly Luminous Quasars in March 1993 with the MPI/ESO 2.2m telescope has revealed that the quasar J03.13 consists of at least two point-like components, constituting therefore a new gravitational lens candidate. Follow-up direct imagery of this interesting object with the New Technology Telescope (NTT) + SUSI in February 1994, using the Bessel B, R and Gunn-i filters, tends to confirm the gravitational lens hypothesis. The mean angular separation and magnitude difference between the A & B images are found to be 0.84"+/-0.03" and 2.1+/-0.1mag, respectively. A spatially unresolved, medium resolution spectrum of J03.13, obtained with the NTT + EMMI in February 1994, shows that the QSO has a redshift z=2.55, with Lyalpha and CIV absorptions at z=2.34 and MgII, MgI and FeII absorptions at z=1.085. The latter absorptions might be associated with a sigma=206km/s lens galaxy. B, R and Gunn-i photometric observations of J03.13 during 1994 and 1995 do not show evidence for flux variations exceeding 0.03mag. HST direct imagery with WFPC2 and FOS spectroscopy of J03.13 A & B are planned during cycle 5. [less ▲]

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See detailThe Clover Leaf Quasar H1413+117: New Photometric Light Curves
Remy, M.; Gosset, Eric ULg; Hutsemekers, Damien ULg et al

in Kochanek, C. S.; Hewitt, Jacqueline N (Eds.) Astrophysical applications of gravitational lensing: proceedings of the 173rd Symposium of the International Astronomical Union (1996)

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See detailJ03.13 AB: A New Multiply Imaged QSO Candidate
Claeskens, Jean-François ULg; Surdej, Jean ULg; Remy, M.

in Kochanek, C. S.; Hewitt, Jacqueline N (Eds.) Astrophysical applications of gravitational lensing: proceedings of the 173rd Symposium of the International Astronomical Union (1996)

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See detailPhotometric monitoring (1987 to 1994) of the gravitational lens candidate UM 425.
Courbin, F.; Magain, Pierre ULg; Remy, M. et al

in Astronomy and Astrophysics (1995), 303

We present the results of a 7 year long photometric monitoring of two components (A and B) of UM 425, thought to be images, separated by 6.5", of the same z=1.47 quasar. These components have been imaged ... [more ▼]

We present the results of a 7 year long photometric monitoring of two components (A and B) of UM 425, thought to be images, separated by 6.5", of the same z=1.47 quasar. These components have been imaged through an R filter in order to obtain their light curves. The photometry was obtained by simultaneously fitting a stellar two-dimensional profile on each component. The brightest image (component A, m_R_=15.7) shows a slow and smooth increase in brightness of 0.2 magnitude in seven years, while the faintest one (component B, m_R_=20.1) displays an outburst of 0.4 magnitude which lasts approximately two years. The variation of component B may be interpreted in two ways, assuming UM 425 is gravitationally lensed. If it is due to an intrinsic variation of the quasar, we derive a lower limit of 3 years on the time delay from the fact that it is not observed in component A. On the other hand, if it is a microlensing "High Amplification Event", we estimate the size of the source to be ~10^-3^pc, in agreement with standard models of AGNs. These observations are consistent with the gravitational lens interpretation of the object. Furthermore, all the CCD frames obtained under the best seeing conditions have been co-added, in an attempt to detect the deflector. The final R image reveals a rich field of faint galaxies in the magnitude range m_R_~22-24. No obvious deflector, nor any system of arcs or arclets is detected, down to a limiting magnitude of m_R_~24. [less ▲]

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See detailTwo new very close pairs of quasars with discordant redshifts and a gravitational lens candidate.
Surdej, Jean ULg; Remy, M.; Smette, A. et al

in Surdej, Jean; Fraipont-Caro, D.; Gosset, Eric (Eds.) et al Gravitational Lenses in the Universe (1993)

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